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A grading system combining architectural features and mitotic count predicts recurrence in stage I lung adenocarcinoma.
Kadota, Kyuichi; Suzuki, Kei; Kachala, Stefan S; Zabor, Emily C; Sima, Camelia S; Moreira, Andre L; Yoshizawa, Akihiko; Riely, Gregory J; Rusch, Valerie W; Adusumilli, Prasad S; Travis, William D
The International Association for the Study of Lung Cancer (IASLC)/American Thoracic Society (ATS)/European Respiratory Society (ERS) has recently proposed a new lung adenocarcinoma classification. We investigated whether nuclear features can stratify prognostic subsets. Slides of 485 stage I lung adenocarcinoma patients were reviewed. We evaluated nuclear diameter, nuclear atypia, nuclear/cytoplasmic ratio, chromatin pattern, prominence of nucleoli, intranuclear inclusions, mitotic count/10 high-power fields (HPFs) or 2.4 mm(2), and atypical mitoses. Tumors were classified into histologic subtypes according to the IASLC/ATS/ERS classification and grouped by architectural grade into low (adenocarcinoma in situ, minimally invasive adenocarcinoma, or lepidic predominant), intermediate (papillary or acinar), and high (micropapillary or solid). Log-rank tests and Cox regression models evaluated the ability of clinicopathologic factors to predict recurrence-free probability. In univariate analyses, nuclear diameter (P=0.007), nuclear atypia (P=0.006), mitotic count (P<0.001), and atypical mitoses (P<0.001) were significant predictors of recurrence. The recurrence-free probability of patients with high mitotic count (≥5/10 HPF: n=175) was the lowest (5-year recurrence-free probability=73%), followed by intermediate (2-4/10 HPF: n=106, 80%), and low (0-1/10 HPF: n=204, 91%, P<0.001). Combined architectural/mitotic grading system stratified patient outcomes (P<0.001): low grade (low architectural grade with any mitotic count and intermediate architectural grade with low mitotic count: n=201, 5-year recurrence-free probability=92%), intermediate grade (intermediate architectural grade with intermediate-high mitotic counts: n=206, 78%), and high grade (high architectural grade with any mitotic count: n=78, 68%). The advantage of adding mitotic count to architectural grade is in stratifying patients with intermediate architectural grade into two prognostically
A fully featured COMBINE archive of a simulation study on syncytial mitotic cycles in Drosophila embryos
Scharm, Martin; Waltemath, Dagmar
COMBINE archives are standardised containers for data files related to a simulation study in computational biology. This manuscript describes a fully featured archive of a previously published simulation study, including (i) the original publication, (ii) the model, (iii) the analyses, and (iv) metadata describing the files and their origin. With the archived data at hand, it is possible to reproduce the results of the original work. The archive can be used for both, educational and research purposes. Anyone may reuse, extend and update the archive to make it a valuable resource for the scientific community. PMID:27830063
High throughput screening of natural products for anti-mitotic effects in MDA-MB-231 human breast carcinoma cells
Mazzio, E; Badisa, R; Mack, N; Deiab, S; Soliman, KFA
Some of the most effective anti-mitotic microtubule-binding agents, such as paclitaxel (Taxus brevifolia) were originally discovered through robust NCI botanical screenings. In this study, a high-through microarray format was utilized to screen 897 aqueous extracts of commonly used natural products (0.00015–0.5 mg/ml) relative to paclitaxel for anti-mitotic effects (independent of toxicity) on proliferation of MDA-MB-231 cells. The data obtained showed that less than 1.34 % tested showed inhibitory growth (IG50) properties <0.0183 mg/ml. The most potent anti-mitotics (independent of toxicity) were Mandrake root (Podophyllum peltatum), Truja Twigs (Thuja occidentalis), Colorado desert mistletoe (Phoradendron flavescens), Tou Gu Cao Speranskia Herb (Speranskia tuberculata), Bentonite Clay, Bunge Root (Pulsatilla chinensis), Brucea Fruit (Brucea javanica), Madder Root (Rubia tinctorum), Gallnut of Chinese Sumac (Melaphis chinensis), Elecampane Root (Inula Helenium), Yuan Zhi Root (Polygala tenuifolia), Pagoda Tree Fruit (Melia Toosendan), Stone Root (Collinsonia Canadensis) and others such as American Witchhazel, Arjun and Bladderwrack. The strongest tumoricidal herbs identified from amongst the subset evaluated for anti-mitotic properties were wild yam (Dioscorea villosa), beth-root (Trillium Pendulum) and alkanet-root (Lithospermum canescens). Additional data was obtained on a lesser-recognized herb: (Speranskia tuberculata) which showed growth inhibition on BT-474 (human ductal breast carcinoma) and Ishikawa (human endometrial adenocarcinoma) cells with ability to block replicative DNA synthesis leading to G2 arrest in MDA-MB-231 cells. In conclusion, these findings present relative potency of natural anti-mitotic resources effective against human breast carcinoma MDA-MB-231 cell division. PMID:24105850
Nup2 requires a highly divergent partner, NupA, to fulfill functions at nuclear pore complexes and the mitotic chromatin region
Markossian, Sarine; Suresh, Subbulakshmi; Osmani, Aysha H.; Osmani, Stephen A.
Chromatin and nuclear pore complexes (NPCs) undergo dramatic changes during mitosis, which in vertebrates and Aspergillus nidulans involves movement of Nup2 from NPCs to the chromatin region to fulfill unknown functions. This transition is shown to require the Cdk1 mitotic kinase and be promoted prematurely by ectopic expression of the NIMA kinase. Nup2 localizes with a copurifying partner termed NupA, a highly divergent yet essential NPC protein. NupA and Nup2 locate throughout the chromatin region during prophase but during anaphase move to surround segregating DNA. NupA function is shown to involve targeting Nup2 to its interphase and mitotic locations. Deletion of either Nup2 or NupA causes identical mitotic defects that initiate a spindle assembly checkpoint (SAC)–dependent mitotic delay and also cause defects in karyokinesis. These mitotic problems are not caused by overall defects in mitotic NPC disassembly–reassembly or general nuclear import. However, without Nup2 or NupA, although the SAC protein Mad1 locates to its mitotic locations, it fails to locate to NPCs normally in G1 after mitosis. Collectively the study provides new insight into the roles of Nup2 and NupA during mitosis and in a surveillance mechanism that regulates nucleokinesis when mitotic defects occur after SAC fulfillment. PMID:25540430
27 T ultra-high static magnetic field changes orientation and morphology of mitotic spindles in human cells
Zhang, Lei; Hou, Yubin; Li, Zhiyuan; Ji, Xinmiao; Wang, Ze; Wang, Huizhen; Tian, Xiaofei; Yu, Fazhi; Yang, Zhenye; Pi, Li; Mitchison, Timothy J; Lu, Qingyou; Zhang, Xin
Purified microtubules have been shown to align along the static magnetic field (SMF) in vitro because of their diamagnetic anisotropy. However, whether mitotic spindle in cells can be aligned by magnetic field has not been experimentally proved. In particular, the biological effects of SMF of above 20 T (Tesla) have never been reported. Here we found that in both CNE-2Z and RPE1 human cells spindle orients in 27 T SMF. The direction of spindle alignment depended on the extent to which chromosomes were aligned to form a planar metaphase plate. Our results show that the magnetic torque acts on both microtubules and chromosomes, and the preferred direction of spindle alignment relative to the field depends more on chromosome alignment than microtubules. In addition, spindle morphology was also perturbed by 27 T SMF. This is the first reported study that investigated the cellular responses to ultra-high magnetic field of above 20 T. Our study not only found that ultra-high magnetic field can change the orientation and morphology of mitotic spindles, but also provided a tool to probe the role of spindle orientation and perturbation in developmental and cancer biology. DOI: http://dx.doi.org/10.7554/eLife.22911.001 PMID:28244368
Selecting Salient Features in High Feature to Exemplar Ratio Conditions
We present an approach for identifying salient input features in high feature to exemplar ratio conditions. Basically we modify the SNR saliency...screening algorithm to improve the solution of the optimal salient feature subset problem. We propose that applying the SNR method to randomly selected...subsets (SRSS) has a superior potential to identify the salient features than the traditional SNR algorithm has. Two experimental studies are provided
The Mitotic Spindle in the One-Cell C. elegans Embryo Is Positioned with High Precision and Stability
NASA Astrophysics Data System (ADS)
Pécréaux, Jacques; Redemann, Stefanie; Alayan, Zahraa; Mercat, Benjamin; Pastezeur, Sylvain; Garzon-Coral, Carlos; Hyman, Anthony A.; Howard, Jonathon
Precise positioning of the mitotic spindle is important for specifying the plane of cell division, which in turn determines how the cytoplasmic contents are partitioned into the daughter cells, and how the daughters are positioned within the tissue. During metaphase in the early C. elegans embryo, the spindle is aligned and centered on the anterior-posterior axis by a microtubule-dependent machinery that exerts restoring forces when the spindle is displaced from the center. To investigate the accuracy and stability of centering, we tracked the position and orientation of the mitotic spindle during the first cell division with high temporal and spatial resolution. We found that the precision is remarkably high: the cell-to-cell variation in the transverse position of the center of the spindle during metaphase, as measured by the standard deviation, was only 1.5% of the length of the short axis of the cell. Spindle position is also very stable: the standard deviation of the fluctuations in transverse spindle position during metaphase was only 0.5% of the short axis of the cell. Assuming that stability is limited by fluctuations in the number of independent motor elements such as microtubules or dyneins underlying the centering machinery, we infer that the number is on the order of one thousand, consistent with the several thousand of astral microtubules in these cells. Astral microtubules grow out from the two spindle poles, make contact with the cell cortex, and then shrink back shortly thereafter. The high stability of centering can be accounted for quantitatively if, while making contact with the cortex, the astral microtubules buckle as they exert compressive, pushing forces. We thus propose that the large number of microtubules in the asters provides a highly precise mechanism for positioning the spindle during metaphase while assembly is completed prior to the onset of anaphase.
Histopathologic Features of Prognostic Significance in High-Grade Osteosarcoma.
Chui, Michael Herman; Kandel, Rita A; Wong, Marcus; Griffin, Anthony M; Bell, Robert S; Blackstein, Martin E; Wunder, Jay S; Dickson, Brendan C
Context .- In osteosarcoma treated with neoadjuvant chemotherapy the extent of tumor necrosis on resection is considered an indicator of treatment response, and this has been shown to correlate with survival in most but not all studies. Objective .- To identify additional histologic variables of prognostic significance in high-grade osteosarcoma. Design .- Slides of pretreatment biopsy and primary postneoadjuvant chemotherapy resections from 165 patients with high-grade osteosarcoma were reviewed. Univariate (Kaplan-Meier) and multivariate (Cox regression) analyses were performed to identify clinical and histomorphologic attributes associated with overall survival. Results .- Univariate analyses confirmed the prognostic significance of metastatic status on presentation, primary tumor size, anatomic site, and histologic subtype. Additionally, the identification of lymphovascular invasion, 10% or more residual viable tumor, and 10 or more mitoses per 10 high-powered fields assessed in posttreatment resections were associated with poor survival, retaining significance in multivariate analyses. Based on results from multivariate analysis, we developed a prognostic index incorporating primary tumor size and site, and significant histologic features assessed on resection (ie, lymphovascular invasion status, mitotic rate, and extent of viable tumor). This scoring system segregates patients into 3 risk categories with significant differences in overall survival and retained significance in an independent validation set of 42 cases. Conclusions .- The integration of clinical and microscopic features improves prognostication of patients with osteosarcoma.
A High Throughput, Whole Cell Screen for Small Molecule Inhibitors of the Mitotic Spindle Checkpoint Identifies OM137, a Novel Aurora Kinase Inhibitor
DeMoe, Joanna H.; Santaguida, Stefano; Daum, John R.; Musacchio, Andrea; Gorbsky, Gary J.
In mitosis the kinetochores of chromosomes that lack full microtubule attachments and/or mechanical tension activate a signaling pathway called the mitotic spindle checkpoint that blocks progression into anaphase and prevents premature segregation of the chromatids until chromosomes become aligned at the metaphase plate (1). The spindle checkpoint is responsible for arresting cells in mitosis in response to chemotherapeutic spindle poisons such as paclitaxel or vinblastine. Some cancer cells show a weakened checkpoint signaling system that may contribute to chromosome instability in tumors. Since complete absence of the spindle checkpoint leads to catastrophic cell division, we reasoned that drugs targeting the checkpoint might provide a therapeutic window in which the checkpoint would be eliminated in cancer cells but sufficiently preserved in normal cells. We developed an assay to identify lead compounds that inhibit the spindle checkpoint. Most cells respond to microtubule drugs by activating the spindle checkpoint and arresting in mitosis with a rounded morphology. Our assay depended on the ability of checkpoint inhibitor compounds to drive mitotic exit and cause cells to flatten onto the substrate in the continuous presence of microtubule drugs. In this study we characterize one of the compounds, OM137, as an inhibitor of Aurora kinases. We find that this compound is growth inhibitory to cultured cells when applied at high concentration and potentiates the growth inhibitory effects of subnanomolar concentrations of paclitaxel. PMID:19190331
Evaluation of Tumor Cell Proliferation by Ki-67 Expression and Mitotic Count in Lymph Node Metastases from Breast Cancer
Aziz, Sura; Wik, Elisabeth; Davidsen, Benedicte; Aas, Hans; Aas, Turid; Akslen, Lars A.
Few studies have addressed the risk of recurrence by assessing proliferation markers in lymph node metastasis from breast cancer. Here, we aimed to examine Ki-67 expression and mitotic count in lymph nodes in comparison with primary tumors. A cohort of node positive breast cancer (n = 168) was studied as a part of the prospective Norwegian Breast Cancer Screening Program (1996–2009). The percentage of Ki-67 positivity was counted per 500 tumor cells in hot-spot areas (x630). Mitotic count was conducted in the most cellular and mitotic active areas in 10 high power fields (x400). Our results showed that Ki-67 and mitotic count were significantly correlated between primary tumor and lymph nodes (Spearman`s correlation 0. 56 and 0.46, respectively) and were associated with most of the histologic features of the primary tumor. Univariate survival analysis (log-rank test) showed that high Ki-67 and mitotic count in the primary tumor and lymph node metastasis significantly predicted risk of recurrence. In multivariate analysis, mitotic count in the lymph node metastasis was an independent predictor of tumor recurrence. In conclusion, proliferation markers in lymph node metastases significantly predicted disease free survival in node positive breast cancer. PMID:26954367
Evaluation of Tumor Cell Proliferation by Ki-67 Expression and Mitotic Count in Lymph Node Metastases from Breast Cancer.
Aziz, Sura; Wik, Elisabeth; Knutsvik, Gøril; Klingen, Tor Audun; Chen, Ying; Davidsen, Benedicte; Aas, Hans; Aas, Turid; Akslen, Lars A
Few studies have addressed the risk of recurrence by assessing proliferation markers in lymph node metastasis from breast cancer. Here, we aimed to examine Ki-67 expression and mitotic count in lymph nodes in comparison with primary tumors. A cohort of node positive breast cancer (n = 168) was studied as a part of the prospective Norwegian Breast Cancer Screening Program (1996-2009). The percentage of Ki-67 positivity was counted per 500 tumor cells in hot-spot areas (x630). Mitotic count was conducted in the most cellular and mitotic active areas in 10 high power fields (x400). Our results showed that Ki-67 and mitotic count were significantly correlated between primary tumor and lymph nodes (Spearman`s correlation 0. 56 and 0.46, respectively) and were associated with most of the histologic features of the primary tumor. Univariate survival analysis (log-rank test) showed that high Ki-67 and mitotic count in the primary tumor and lymph node metastasis significantly predicted risk of recurrence. In multivariate analysis, mitotic count in the lymph node metastasis was an independent predictor of tumor recurrence. In conclusion, proliferation markers in lymph node metastases significantly predicted disease free survival in node positive breast cancer.
Prognostic relevance of the mitotic count and the amount of viable tumour after neoadjuvant chemotherapy for primary, localised, high-grade soft tissue sarcoma
Andreou, D; Werner, M; Pink, D; Traub, F; Schuler, M; Gosheger, G; Jobke, B; Reichardt, P; Tunn, P U
Background: We sought to examine whether mitotic count (MC) and the amount of viable tumour (VT) following neoadjuvant systemic chemotherapy (SC) for primary, localised, high-grade soft tissue sarcoma (STS) correlate with prognosis. Methods: Retrospective analysis of 57 patients who underwent SC involving a combination of an anthracycline and an alkylating agent, followed by surgical resection between 2001 and 2011. Results: The amount of VT after chemotherapy was significantly associated with disease-specific survival (DSS) and event-free survival (EFS). Patients with <10% VT had a DSS of 94% at 5 years, compared with 61% for patients with ⩾10% VT (P=0.033); EFS was 75%, compared with 48% (P=0.030). Patients with an MC of ⩾20/10 high power fields (HPF) after chemotherapy had a significantly lower DSS (33% vs 84% at 5 years, P<0.001) and EFS (40% vs 63% at 5 years, P=0.019) than patients with an MC of <20/10 HPF. Conclusions: The MC and the amount of VT after neoadjuvant therapy for primary, localised, high-grade STS appear to correlate with prognosis. If these results are validated prospectively, then they could provide a rational for the design of neoadjuvant treatment modification/escalation studies, analogue to the EURAMOS-1 trial for bone sarcomas. PMID:25535732
A Framework for Image-Based Classification of Mitotic Cells in Asynchronous Populations
Slattery, Scott D.; Newberg, Justin Y.; Szafran, Adam T.; Hall, Rebecca M.; Brinkley, Bill R.
Abstract High content screening (HCS) has emerged an important tool for drug discovery because it combines rich readouts of cellular responses in a single experiment. Inclusion of cell cycle analysis into HCS is essential to identify clinically suitable anticancer drugs that disrupt the aberrant mitotic activity of cells. One challenge for integration of cell cycle analysis into HCS is that cells must be chemically synchronized to specific phases, adding experimental complexity to high content screens. To address this issue, we have developed a rules-based method that utilizes mitotic phosphoprotein monoclonal 2 (MPM-2) marker and works consistently in different experimental conditions and in asynchronous populations. Further, the performance of the rules-based method is comparable to established machine learning approaches for classifying cell cycle data, indicating the robustness of the features we use in the framework. As such, we suggest the use of MPM-2 analysis and its associated expressive features for integration into HCS approaches. PMID:22084958
Cells transformed by PLC-gamma 1 overexpression are highly sensitive to clostridium difficile toxin A-induced apoptosis and mitotic inhibition.
Nam, Hyo Jung; Kang, Jin Ku; Chang, Jong Soo; Lee, Min Soo; Nam, Seung Taek; Jung, Hyun Woo; Kim, Sung-Kuk; Ha, Eun-Mi; Seok, Heon; Son, Seung Woo; Park, Young Joo; Kim, Ho
Phospholipase C-γl (PLC-γl) expression is associated with cellular transformation. Notably, PLC-gamma is up-regulated in colorectal cancer tissue and breast carcinoma. Because exotoxins released by Clostridium botulinum have been shown to induce apoptosis and promote growth arrest in various cancer cell lines, we examined here the potential of Clostridium difficile toxin A to selectively induce apoptosis in cells transformed by PLC-γl overexpression. We found that PLC-γl-transformed cells, but not vectortransformed (control) cells, were highly sensitive to C. difficile toxin A-induced apoptosis and mitotic inhibition. Moreover, expression of the proapoptotic Bcl2 family member, Bim, and activation of caspase-3 were significantly up-regulated by toxin A in PLC-γl-transformed cells. Toxin A-induced cell rounding and paxillin dephosphorylation were also significantly higher in PLC-γl-transformed cells than in control cells. These findings suggest that C. difficile toxin A may have potential as an anticancer agent against colorectal cancers and breast carcinomas in which PLC-γl is highly up-regulated.
Variations of mitotic index in normal and dysplastic squamous epithelium of the uterine cervix as a function of endometrial maturation.
Fadare, Oluwole; Yi, Xiaofang; Liang, Sharon X; Ma, Yanling; Zheng, Wenxin
Cervical intraepithelial neoplasia is a premalignant (dysplastic) lesion that is characterized by abnormal cellular proliferation, maturation and nuclear atypia. The intraepithelial distribution, density, and nature (typical or atypical) of mitotic figures are routinely utilized diagnostic criteria to grade dysplasia and to distinguish high-grade dysplasia from potential histologic mimics such as transitional metaplasia, atrophy or immature squamous metaplasia. In this study, we evaluated the total mitotic indices of the cervical epithelia in hysterectomy specimens from patients with and without dysplastic lesions and investigated a possible relationship between mitotic index and hormonal status, using the endometrial maturation phase as a surrogate indicator of the latter. Two hundred seventy-four cervices from hysterectomy specimens (135 cases without dysplasia, 33, 35 and 71 cases with grades 1, 2 and 3 cervical intraepithelial neoplasia, respectively) were analyzed. A cervical mitotic index (total mitotic figures/10 high-power fields in the most proliferative area) was determined for each case. The endometrium in each case was classified into atrophic, early proliferative, late proliferative and secretory. For all three dysplasia grades, cases in the proliferative endometrium group always had a higher average mitotic index than those in the secretory and atrophic endometrium groups; this observation also held true for the benign cases. Furthermore, in all three dysplasia grades, the average mitotic index was always lowest in the atrophic endometrium group. Although the mitotic index showed expected patterns of increases with increasing dysplasia grades for most of the endometrial phases, this was not a universal finding. Notably, the average mitotic index for our cervical intraepithelial neoplasia 1 cases with late proliferative endometrium was higher than our cervical intraepithelial neoplasia 2 cases with secretory and atrophic endometrium. It is concluded
Mitotic chromosome condensation in vertebrates
Vagnarelli, Paola
Work from several laboratories over the past 10-15 years has revealed that, within the interphase nucleus, chromosomes are organized into spatially distinct territories [T. Cremer, C. Cremer, Chromosome territories, nuclear architecture and gene regulation in mammalian cells, Nat. Rev. Genet. 2 (2001) 292-301 and T. Cremer, M. Cremer, S. Dietzel, S. Muller, I. Solovei, S. Fakan, Chromosome territories-a functional nuclear landscape, Curr. Opin. Cell Biol. 18 (2006) 307-316]. The overall compaction level and intranuclear location varies as a function of gene density for both entire chromosomes [J.A. Croft, J.M. Bridger, S. Boyle, P. Perry, P. Teague,W.A. Bickmore, Differences in the localization and morphology of chromosomes in the human nucleus, J. Cell Biol. 145 (1999) 1119-1131] and specific chromosomal regions [N.L. Mahy, P.E. Perry, S. Gilchrist, R.A. Baldock, W.A. Bickmore, Spatial organization of active and inactive genes and noncoding DNA within chromosome territories, J. Cell Biol. 157 (2002) 579-589] (Fig. 1A, A'). In prophase, when cyclin B activity reaches a high threshold, chromosome condensation occurs followed by Nuclear Envelope Breakdown (NEB) [1]. At this point vertebrate chromosomes appear as compact structures harboring an attachment point for the spindle microtubules physically recognizable as a primary constriction where the two sister chromatids are held together. The transition from an unshaped interphase chromosome to the highly structured mitotic chromosome (compare Figs. 1A and B) has fascinated researchers for several decades now; however a definite picture of how this process is achieved and regulated is not yet in our hands and it will require more investigation to comprehend the complete process. From a biochemical point of view a vertebrate mitotic chromosomes is composed of DNA, histone proteins (60%) and non-histone proteins (40%) [6]. I will discuss below what is known to date on the contribution of these two different classes of
Cell biology of mitotic recombination.
Lisby, Michael; Rothstein, Rodney
Homologous recombination provides high-fidelity DNA repair throughout all domains of life. Live cell fluorescence microscopy offers the opportunity to image individual recombination events in real time providing insight into the in vivo biochemistry of the involved proteins and DNA molecules as well as the cellular organization of the process of homologous recombination. Herein we review the cell biological aspects of mitotic homologous recombination with a focus on Saccharomyces cerevisiae and mammalian cells, but will also draw on findings from other experimental systems. Key topics of this review include the stoichiometry and dynamics of recombination complexes in vivo, the choreography of assembly and disassembly of recombination proteins at sites of DNA damage, the mobilization of damaged DNA during homology search, and the functional compartmentalization of the nucleus with respect to capacity of homologous recombination.
Cell Biology of Mitotic Recombination
Lisby, Michael; Rothstein, Rodney
Homologous recombination provides high-fidelity DNA repair throughout all domains of life. Live cell fluorescence microscopy offers the opportunity to image individual recombination events in real time providing insight into the in vivo biochemistry of the involved proteins and DNA molecules as well as the cellular organization of the process of homologous recombination. Herein we review the cell biological aspects of mitotic homologous recombination with a focus on Saccharomyces cerevisiae and mammalian cells, but will also draw on findings from other experimental systems. Key topics of this review include the stoichiometry and dynamics of recombination complexes in vivo, the choreography of assembly and disassembly of recombination proteins at sites of DNA damage, the mobilization of damaged DNA during homology search, and the functional compartmentalization of the nucleus with respect to capacity of homologous recombination. PMID:25731763
Automated segmentation of the first mitotic spindle in differential interference contrast microcopy images of C. elegans embryos.
Farhadifar, Reza; Needleman, Daniel
Differential interference contrast (DIC) microscopy is a non-fluorescent microscopy technique that is commonly used to visualize the first mitotic spindle in C. elegans embryos. DIC movies are easy to acquire and provide data with high spatial and temporal resolution, allowing detailed investigations of the dynamics of the spindle-which elongates, oscillates, and is positioned asymmetrically. Despite the immense amount of information such movies provide, they are normally only used to draw qualitative conclusion based on manual inspection. We have developed an algorithm to automatically segment the mitotic spindle in DIC movies of C. elegans embryos, determine the position of centrosomes, quantify the morphology and motions of the spindle, and track these features over time. This method should be widely useful for studying the first mitotic spindle in C. elegans.
Immunochemical studies of 22S protein from isolated mitotic apparatus.
Bibring, T; Baxandall, J
Evidence is presented that the "22S protein" of mitotic apparatus isolated from sea urchin eggs is not microtubule protein. An antibody preparation active against 22S protein is described, and immunochemical studies of the distribution of 22S protein in various cellular fractions and among morphological features of mitotic apparatus are reported. The protein is ubiquitous in the metaphase egg fractions that were tested but is not found in sperm flagella. It is immunologically distinct from proposed microtubule protein isolated from mitotic apparatus by the method of Sakai, and from proposed microtubule protein obtained after extraction with mild acid. It exists in nontubule material of isolated mitotic apparatus but is not detectable in microtubules.
Bibring, Thomas; Baxandall, Jane
Evidence is presented that the "22S protein" of mitotic apparatus isolated from sea urchin eggs is not microtubule protein. An antibody preparation active against 22S protein is described, and immunochemical studies of the distribution of 22S protein in various cellular fractions and among morphological features of mitotic apparatus are reported. The protein is ubiquitous in the metaphase egg fractions that were tested but is not found in sperm flagella. It is immunologically distinct from proposed microtubule protein isolated from mitotic apparatus by the method of Sakai, and from proposed microtubule protein obtained after extraction with mild acid. It exists in nontubule material of isolated mitotic apparatus but is not detectable in microtubules. PMID:4977446
Chemically diverse microtubule stabilizing agents initiate distinct mitotic defects and dysregulated expression of key mitotic kinases.
Rohena, Cristina C; Peng, Jiangnan; Johnson, Tyler A; Crews, Phillip; Mooberry, Susan L
Microtubule stabilizers are some of the most successful drugs used in the treatment of adult solid tumors and yet the molecular events responsible for their antimitotic actions are not well defined. The mitotic events initiated by three structurally and biologically diverse microtubule stabilizers; taccalonolide AJ, laulimalide/fijianolide B and paclitaxel were studied. These microtubule stabilizers cause the formation of aberrant, but structurally distinct mitotic spindles leading to the hypothesis that they differentially affect mitotic signaling. Each microtubule stabilizer initiated different patterns of expression of key mitotic signaling proteins. Taccalonolide AJ causes centrosome separation and disjunction failure to a much greater extent than paclitaxel or laulimalide, which is consistent with the distinct defects in expression and activation of Plk1 and Eg5 caused by each stabilizer. Localization studies revealed that TPX2 and Aurora A are associated with each spindle aster formed by each stabilizer. This suggests a common mechanism of aster formation. However, taccalonolide AJ also causes pericentrin accumulation on every spindle aster. The presence of pericentrin at every spindle aster initiated by taccalonolide AJ might facilitate the maintenance and stability of the highly focused asters formed by this stabilizer. Laulimalide and paclitaxel cause completely different patterns of expression and activation of these proteins, as well as phenotypically different spindle phenotypes. Delineating how diverse microtubule stabilizers affect mitotic signaling pathways could identify key proteins involved in modulating sensitivity and resistance to the antimitotic actions of these compounds.
Chemically Diverse Microtubule Stabilizing Agents Initiate Distinct Mitotic Defects and Dysregulated Expression of Key Mitotic Kinases
Rohena, Cristina C.; Peng, Jiangnan; Johnson, Tyler A.; Crews, Phillip; Mooberry, Susan L.
Microtubule stabilizers are some of the most successful drugs used in the treatment of adult solid tumors and yet the molecular events responsible for their antimitotic actions are not well defined. The mitotic events initiated by three structurally and biologically diverse microtubule stabilizers; taccalonolide AJ, laulimalide/fijianolide B and paclitaxel were studied. These microtubule stabilizers cause the formation of aberrant, but structurally distinct mitotic spindles leading to the hypothesis that they differentially affect mitotic signaling. Each microtubule stabilizer initiated different patterns of expression of key mitotic signaling proteins. Taccalonolide AJ causes centrosome separation and disjunction failure to a much greater extent than paclitaxel or laulimalide, which is consistent with the distinct defects in expression and activation of Plk1 and Eg5 caused by each stabilizer. Localization studies revealed that TPX2 and Aurora A are associated with each spindle aster formed by each stabilizer. This suggests a common mechanism of aster formation. However, taccalonolide AJ also causes pericentrin accumulation on every spindle aster. The presence of pericentrin at every spindle aster initiated by taccalonolide AJ might facilitate the maintenance and stability of the highly focused asters formed by this stabilizer. Laulimalide and paclitaxel cause completely different patterns of expression and activation of these proteins, as well as phenotypically different spindle phenotypes. Delineating how diverse microtubule stabilizers affect mitotic signaling pathways could identify key proteins involved in modulating sensitivity and resistance to the antimitotic actions of these compounds. PMID:23399639
Clasp2 ensures mitotic fidelity and prevents differentiation of epidermal keratinocytes
Shahbazi, Marta N.; Peña-Jimenez, Daniel; Antonucci, Francesca; Drosten, Matthias
ABSTRACT Epidermal homeostasis is tightly controlled by a balancing act of self-renewal or terminal differentiation of proliferating basal keratinocytes. An increase in DNA content as a consequence of a mitotic block is a recognized mechanism underlying keratinocyte differentiation, but the molecular mechanisms involved in this process are not yet fully understood. Using cultured primary keratinocytes, here we report that the expression of the mammalian microtubule and kinetochore-associated protein Clasp2 is intimately associated with the basal proliferative makeup of keratinocytes, and its deficiency leads to premature differentiation. Clasp2-deficient keratinocytes exhibit increased centrosomal numbers and numerous mitotic alterations, including multipolar spindles and chromosomal misalignments that overall result in mitotic stress and a high DNA content. Such mitotic block prompts premature keratinocyte differentiation in a p53-dependent manner in the absence of cell death. Our findings reveal a new role for Clasp2 in governing keratinocyte undifferentiated features and highlight the presence of surveillance mechanisms that prevent cell cycle entry in cells that have alterations in the DNA content. PMID:28069833
Mitotic Exit Control as an Evolved Complex System
Bosl, W; Li, R
The exit from mitosis is the last critical decision a cell has to make during a division cycle. A complex regulatory system has evolved to evaluate the success of mitotic events and control this decision. Whereas outstanding genetic work in yeast has led to rapid discovery of a large number of interacting genes involved in the control of mitotic exit, it has also become increasingly difficult to comprehend the logic and mechanistic features embedded in the complex molecular network. Our view is that this difficulty stems in part from the attempt to explain mitotic exit control using concepts from traditional top-down engineering design, and that exciting new results from evolutionary engineering design applied to networks and electronic circuits may lend better insights. We focus on four particularly intriguing features of the mitotic exit control system: the two-stepped release of Cdc14; the self-activating nature of Tem1 GTPase; the spatial sensor associated with the spindle pole body; and the extensive redundancy in the mitotic exit network. We attempt to examine these design features from the perspective of evolutionary design and complex system engineering.
Energy Conservation Featured in Illinois High School
ERIC Educational Resources Information Center
Modern Schools, 1976
The William Fremd High School in Palatine, Illinois, scheduled to open in 1977, is being built with energy conservation uppermost in mind. In this system, 70 heat pumps will heat and cool 300,000 square feet of educational facilities. (Author/MLF)
High dimensional feature reduction via projection pursuit
NASA Technical Reports Server (NTRS)
Jimenez, Luis; Landgrebe, David
The recent development of more sophisticated remote sensing systems enables the measurement of radiation in many more spectral intervals than previously possible. An example of that technology is the AVIRIS system, which collects image data in 220 bands. As a result of this, new algorithms must be developed in order to analyze the more complex data effectively. Data in a high dimensional space presents a substantial challenge, since intuitive concepts valid in a 2-3 dimensional space to not necessarily apply in higher dimensional spaces. For example, high dimensional space is mostly empty. This results from the concentration of data in the corners of hypercubes. Other examples may be cited. Such observations suggest the need to project data to a subspace of a much lower dimension on a problem specific basis in such a manner that information is not lost. Projection Pursuit is a technique that will accomplish such a goal. Since it processes data in lower dimensions, it should avoid many of the difficulties of high dimensional spaces. In this paper, we begin the investigation of some of the properties of Projection Pursuit for this purpose.
Meiotic and mitotic recombination in meiosis.
Kohl, Kathryn P; Sekelsky, Jeff
Meiotic crossovers facilitate the segregation of homologous chromosomes and increase genetic diversity. The formation of meiotic crossovers was previously posited to occur via two pathways, with the relative use of each pathway varying between organisms; however, this paradigm could not explain all crossovers, and many of the key proteins involved were unidentified. Recent studies that identify some of these proteins reinforce and expand the model of two meiotic crossover pathways. The results provide novel insights into the evolutionary origins of the pathways, suggesting that one is similar to a mitotic DNA repair pathway and the other evolved to incorporate special features unique to meiosis.
[Medical image retrieval by high level semantic features and low level content features of image].
Xie, Tianwen; Tang, Weijun; Zhao, Qiufeng; Zhao, Jiaao
Content-based image retrieval aims at searching the similar images using low level features,and medical image retrieval needs it for the retrieval of similar images. Medical images contain not only a lot of content data, but also a lot of semantic information. This paper presents an approach by combining digital imaging and communications in medicine (DICOM) features and low level features to perform retrieval on medical image databases. At the first step, the semantic information is extracted from DICOM header for the pre-filtering of the images, and then dual-tree complex wavelet transfrom(DT-CWT) features of pre-filtered images and example images are extracted to retrieve similar images. Experimental results show that by combining the high level semantics (DICOM features) and low level content features (texture) the retrieval time is reduced and the performance of medical image retrieval is increased.
Measuring mitotic spindle dynamics in budding yeast
NASA Astrophysics Data System (ADS)
Plumb, Kemp
In order to carry out its life cycle and produce viable progeny through cell division, a cell must successfully coordinate and execute a number of complex processes with high fidelity, in an environment dominated by thermal noise. One important example of such a process is the assembly and positioning of the mitotic spindle prior to chromosome segregation. The mitotic spindle is a modular structure composed of two spindle pole bodies, separated in space and spanned by filamentous proteins called microtubules, along which the genetic material of the cell is held. The spindle is responsible for alignment and subsequent segregation of chromosomes into two equal parts; proper spindle positioning and timing ensure that genetic material is appropriately divided amongst mother and daughter cells. In this thesis, I describe fluorescence confocal microscopy and automated image analysis algorithms, which I have used to observe and analyze the real space dynamics of the mitotic spindle in budding yeast. The software can locate structures in three spatial dimensions and track their movement in time. By selecting fluorescent proteins which specifically label the spindle poles and cell periphery, mitotic spindle dynamics have been measured in a coordinate system relevant to the cell division. I describe how I have characterised the accuracy and precision of the algorithms by simulating fluorescence data for both spindle poles and the budding yeast cell surface. In this thesis I also describe the construction of a microfluidic apparatus that allows for the measurement of long time-scale dynamics of individual cells and the development of a cell population. The tools developed in this thesis work will facilitate in-depth quantitative analysis of the non-equilibrium processes in living cells.
Micromechanics of human mitotic chromosomes
NASA Astrophysics Data System (ADS)
Sun, Mingxuan; Kawamura, Ryo; Marko, John F.
Eukaryote cells dramatically reorganize their long chromosomal DNAs to facilitate their physical segregation during mitosis. The internal organization of folded mitotic chromosomes remains a basic mystery of cell biology; its understanding would likely shed light on how chromosomes are separated from one another as well as into chromosome structure between cell divisions. We report biophysical experiments on single mitotic chromosomes from human cells, where we combine micromanipulation, nano-Newton-scale force measurement and biochemical treatments to study chromosome connectivity and topology. Results are in accord with previous experiments on amphibian chromosomes and support the 'chromatin network' model of mitotic chromosome structure. Prospects for studies of chromosome-organizing proteins using siRNA expression knockdowns, as well as for differential studies of chromosomes with and without mutations associated with genetic diseases, are also discussed.
Myosin-10 independently influences mitotic spindle structure and mitotic progression.
Sandquist, Joshua C; Larson, Matthew E; Hine, Ken J
The iconic bipolar structure of the mitotic spindle is of extreme importance to proper spindle function. At best, spindle abnormalities result in a delayed mitosis, while worse outcomes include cell death or disease. Recent work has uncovered an important role for the actin-based motor protein myosin-10 in the regulation of spindle structure and function. Here we examine the contribution of the myosin tail homology 4 (MyTH4) domain of the myosin-10 tail to the protein's spindle functions. The MyTH4 domain is known to mediate binding to microtubules and we verify the suspicion that this domain contributes to myosin-10's close association with the spindle. More surprisingly, our data demonstrate that some but not all of myosin-10's spindle functions require microtubule binding. In particular, myosin-10's contribution to spindle pole integrity requires microtubule binding, whereas its contribution to normal mitotic progression does not. This is demonstrated by the observation that dominant negative expression of the wild-type MyTH4 domain produces multipolar spindles and an increased mitotic index, whereas overexpression of a version of the MyTH4 domain harboring point mutations that abrogate microtubule binding results in only the mitotic index phenotype. Our data suggest that myosin-10 helps to control the metaphase to anaphase transition in cells independent of microtubule binding. © 2016 Wiley Periodicals, Inc.
High-resolution Urban Image Classification Using Extended Features
Vatsavai, Raju
High-resolution image classification poses several challenges because the typical object size is much larger than the pixel resolution. Any given pixel (spectral features at that location) by itself is not a good indicator of the object it belongs to without looking at the broader spatial footprint. Therefore most modern machine learning approaches that are based on per-pixel spectral features are not very effective in high- resolution urban image classification. One way to overcome this problem is to extract features that exploit spatial contextual information. In this study, we evaluated several features in- cluding edge density, texture, and morphology. Several machine learning schemes were tested on the features extracted from a very high-resolution remote sensing image and results were presented.
OVARIAN LOW-GRADE AND HIGH-GRADE SEROUS CARCINOMA: Pathogenesis, Clinicopathologic and Molecular Biologic Features, and Diagnostic Problems
Vang, Russell; Shih, Ie-Ming; Kurman, Robert J.
Ovarian serous carcinomas have been graded using various systems. Recently, a 2-tier system in which tumors are subdivided into low-grade and high-grade has been proposed. This approach is simplistic, reproducible, and based on biologic evidence indicating that both tumors develop via different pathways. Low-grade serous carcinomas exhibit low-grade nuclei with infrequent mitotic figures. They evolve from adenofibromas or borderline tumors, have frequent mutations of the KRAS, BRAF, or ERBB2 genes, and lack TP53 mutations (Type I pathway). The progression to invasive carcinoma is a slow step-wise process. Low-grade tumors are indolent and have better outcome than high-grade tumors. In contrast, high-grade serous carcinomas have high-grade nuclei and numerous mitotic figures. Identification of a precursor lesion in the ovary has been elusive and therefore the origin of ovarian carcinoma has been described as de novo. More recently, studies have suggested that a proportion appear to originate from intraepithelial carcinoma in the fallopian tube. The development of these tumors is rapid (Type II pathway). The vast majority are characterized by TP53 mutations and lack mutations of KRAS, BRAF, or ERBB2. Although both types of serous carcinomas evolve along different pathways, rare high-grade serous carcinomas seem to arise through the Type I pathway. Immunohistochemical stains for p53, p16, and Ki-67 for distinction of low- from high-grade tumors are of limited value but can be helpful in selected instances. This review provides an update on the pathogenesis and clinicopathologic features of these two types of serous carcinomas and addresses some of the diagnostic problems that are encountered in routine practice. PMID:19700937
Unsupervised Feature Learning for High-Resolution Satellite Image Classification
Cheriyadat, Anil M
The rich data provided by high-resolution satellite imagery allow us to directly model geospatial neighborhoods by understanding their spatial and structural patterns. In this paper we explore an unsupervised feature learning approach to model geospatial neighborhoods for classification purposes. While pixel and object based classification approaches are widely used for satellite image analysis, often these approaches exploit the high-fidelity image data in a limited way. In this paper we extract low-level features to characterize the local neighborhood patterns. We exploit the unlabeled feature measurements in a novel way to learn a set of basis functions to derive new features. The derived sparse feature representation obtained by encoding the measured features in terms of the learned basis function set yields superior classification performance. We applied our technique on two challenging image datasets: ORNL dataset representing one-meter spatial resolution satellite imagery representing five land-use categories and, UCMERCED dataset consisting of 21 different categories representing sub-meter resolution overhead imagery. Our results are highly promising and, in the case of UCMERCED dataset we outperform the best results obtained for this dataset. We show that our feature extraction and learning methods are highly effective in developing a detection system that can be used to automatically scan large-scale high-resolution satellite imagery for detecting large-facility.
Adenovirus Replaces Mitotic Checkpoint Controls
Turner, Roberta L.; Groitl, Peter; Dobner, Thomas
ABSTRACT Infection with adenovirus triggers the cellular DNA damage response, elements of which include cell death and cell cycle arrest. Early adenoviral proteins, including the E1B-55K and E4orf3 proteins, inhibit signaling in response to DNA damage. A fraction of cells infected with an adenovirus mutant unable to express the E1B-55K and E4orf3 genes appeared to arrest in a mitotic-like state. Cells infected early in G1 of the cell cycle were predisposed to arrest in this state at late times of infection. This arrested state, which displays hallmarks of mitotic catastrophe, was prevented by expression of either the E1B-55K or the E4orf3 genes. However, E1B-55K mutant virus-infected cells became trapped in a mitotic-like state in the presence of the microtubule poison colcemid, suggesting that the two viral proteins restrict entry into mitosis or facilitate exit from mitosis in order to prevent infected cells from arresting in mitosis. The E1B-55K protein appeared to prevent inappropriate entry into mitosis through its interaction with the cellular tumor suppressor protein p53. The E4orf3 protein facilitated exit from mitosis by possibly mislocalizing and functionally inactivating cyclin B1. When expressed in noninfected cells, E4orf3 overcame the mitotic arrest caused by the degradation-resistant R42A cyclin B1 variant. IMPORTANCE Cells that are infected with adenovirus type 5 early in G1 of the cell cycle are predisposed to arrest in a mitotic-like state in a p53-dependent manner. The adenoviral E1B-55K protein prevents entry into mitosis. This newly described activity for the E1B-55K protein appears to depend on the interaction between the E1B-55K protein and the tumor suppressor p53. The adenoviral E4orf3 protein facilitates exit from mitosis, possibly by altering the intracellular distribution of cyclin B1. By preventing entry into mitosis and by promoting exit from mitosis, these adenoviral proteins act to prevent the infected cell from arresting in a
Data Feature Extraction for High-Rate 3-Phase Data
This algorithm processes high-rate 3-phase signals to identify the start time of each signal and estimate its envelope as data features. The start time and magnitude of each signal during the steady state is also extracted. The features can be used to detect abnormal signals. This algorithm is developed to analyze Exxeno's 3-phase voltage and current data recorded from refrigeration systems to detect device failure or degradation.
Exploring KM Features of High-Performance Companies
NASA Astrophysics Data System (ADS)
Wu, Wei-Wen
For reacting to an increasingly rival business environment, many companies emphasize the importance of knowledge management (KM). It is a favorable way to explore and learn KM features of high-performance companies. However, finding out the critical KM features of high-performance companies is a qualitative analysis problem. To handle this kind of problem, the rough set approach is suitable because it is based on data-mining techniques to discover knowledge without rigorous statistical assumptions. Thus, this paper explored KM features of high-performance companies by using the rough set approach. The results show that high-performance companies stress the importance on both tacit and explicit knowledge, and consider that incentives and evaluations are the essentials to implementing KM.
Mechanisms of Mitotic Spindle Assembly
Petry, Sabine
Life depends on cell proliferation and the accurate segregation of chromosomes, which are mediated by the microtubule (MT)-based mitotic spindle and ~200 essential MT-associated proteins. Yet, a mechanistic understanding of how the mitotic spindle is assembled and achieves chromosome segregation is still missing. This is mostly due to the density of MTs in the spindle, which presumably precludes their direct observation. Recent insight has been gained into the molecular building plan of the metaphase spindle using bulk and single-molecule measurements combined with computational modeling. MT nucleation was uncovered as a key principle of spindle assembly, and mechanistic details about MT nucleation pathways and their coordination are starting to be revealed. Lastly, advances in studying spindle assembly can be applied to address the molecular mechanisms of how the spindle segregates chromosomes. PMID:27145846
Loops determine the mechanical properties of mitotic chromosomes
NASA Astrophysics Data System (ADS)
Zhang, Yang; Heermann, Dieter W.
In mitosis, chromosomes undergo a condensation into highly compacted, rod-like objects. Many models have been put forward for the higher-order organization of mitotic chromosomes including radial loop and hierarchical folding models. Additionally, mechanical properties of mitotic chromosomes under different conditions were measured. However, the internal organization of mitotic chromosomes still remains unclear. Here we present a polymer model for mitotic chromosomes and show how chromatin loops play a major role for their mechanical properties. The key assumption of the model is the ability of the chromatin fibre to dynamically form loops with the help of binding proteins. Our results show that looping leads to a tight compaction and significantly increases the bending rigidity of chromosomes. Moreover, our qualitative prediction of the force elongation behaviour is close to experimental findings. This indicates that the internal structure of mitotic chromosomes is based on self-organization of the chromatin fibre. We also demonstrate how number and size of loops have a strong influence on the mechanical properties. We suggest that changes in the mechanical characteristics of chromosomes can be explained by an altered internal loop structure. YZ gratefully appreciates funding by the German National Academic Foundation (Studienstiftung des deutschen Volkes) and support by the Heidelberg Graduate School for Mathematical and Computational Methods in the Sciences (HGS MathComp).
Spectral feature design in high dimensional multispectral data
NASA Technical Reports Server (NTRS)
Chen, Chih-Chien Thomas; Landgrebe, David A.
The High resolution Imaging Spectrometer (HIRIS) is designed to acquire images simultaneously in 192 spectral bands in the 0.4 to 2.5 micrometers wavelength region. It will make possible the collection of essentially continuous reflectance spectra at a spectral resolution sufficient to extract significantly enhanced amounts of information from return signals as compared to existing systems. The advantages of such high dimensional data come at a cost of increased system and data complexity. For example, since the finer the spectral resolution, the higher the data rate, it becomes impractical to design the sensor to be operated continuously. It is essential to find new ways to preprocess the data which reduce the data rate while at the same time maintaining the information content of the high dimensional signal produced. Four spectral feature design techniques are developed from the Weighted Karhunen-Loeve Transforms: (1) non-overlapping band feature selection algorithm; (2) overlapping band feature selection algorithm; (3) Walsh function approach; and (4) infinite clipped optimal function approach. The infinite clipped optimal function approach is chosen since the features are easiest to find and their classification performance is the best. After the preprocessed data has been received at the ground station, canonical analysis is further used to find the best set of features under the criterion that maximal class separability is achieved. Both 100 dimensional vegetation data and 200 dimensional soil data were used to test the spectral feature design system. It was shown that the infinite clipped versions of the first 16 optimal features had excellent classification performance. The overall probability of correct classification is over 90 percent while providing for a reduced downlink data rate by a factor of 10.
Plk2 regulates mitotic spindle orientation and mammary gland development.
Villegas, Elizabeth; Kabotyanski, Elena B; Shore, Amy N; Creighton, Chad J; Westbrook, Thomas F; Rosen, Jeffrey M
Disruptions in polarity and mitotic spindle orientation contribute to the progression and evolution of tumorigenesis. However, little is known about the molecular mechanisms regulating these processes in vivo. Here, we demonstrate that Polo-like kinase 2 (Plk2) regulates mitotic spindle orientation in the mammary gland and that this might account for its suggested role as a tumor suppressor. Plk2 is highly expressed in the mammary gland and is required for proper mammary gland development. Loss of Plk2 leads to increased mammary epithelial cell proliferation and ductal hyperbranching. Additionally, a novel role for Plk2 in regulating the orientation of the mitotic spindle and maintaining proper cell polarity in the ductal epithelium was discovered. In support of a tumor suppressor function for Plk2, loss of Plk2 increased the formation of lesions in multiparous glands. Collectively, these results demonstrate a novel role for Plk2 in regulating mammary gland development.
Photoionization of Ca XV with high energy features
NASA Astrophysics Data System (ADS)
Nahar, Sultana N.
Photoionization cross sections of (Ca XV + hν → Ca XVI + e), with high energy resonant photo-absorption phenomena, of a large number of bound states, 701 in total with n ≤ 10 and l ≤ 9, are reported. They are obtained using the R-matrix method with a close coupling (CC) wavefunction expansion of 29 states of n = 2,3 complexes of the core ion Ca XVI. Characteristic features found in photoionization of the ion are illustrated with examples. The cross section (σPI) of the ground 2s22p2(3P) state is found to be unaffected by the size of the wavefunction expansion except for weak sparse resonances in high energy region. However, effects on excited states are considerable as the core excitations to n = 3 states are manifested in huge resonant absorption in high energy photoionization. They show existence of prominent high peak resonant features and enhancement in the background that were not studied before for Ca XV. In addition photoionization of the excited states with a single valence electron is dominated by Seaton resonant structures formed by the photo-excitation-of-core in the high energy region. These features will impact other quantities, such as the opacity, electron-ion recombination in high temperature plasmas where the ion exists, and hence will play important role in determination of elemental abundances in the astronomical objects.
Feature extraction and classification algorithms for high dimensional data
NASA Technical Reports Server (NTRS)
Lee, Chulhee; Landgrebe, David
Feature extraction and classification algorithms for high dimensional data are investigated. Developments with regard to sensors for Earth observation are moving in the direction of providing much higher dimensional multispectral imagery than is now possible. In analyzing such high dimensional data, processing time becomes an important factor. With large increases in dimensionality and the number of classes, processing time will increase significantly. To address this problem, a multistage classification scheme is proposed which reduces the processing time substantially by eliminating unlikely classes from further consideration at each stage. Several truncation criteria are developed and the relationship between thresholds and the error caused by the truncation is investigated. Next an approach to feature extraction for classification is proposed based directly on the decision boundaries. It is shown that all the features needed for classification can be extracted from decision boundaries. A characteristic of the proposed method arises by noting that only a portion of the decision boundary is effective in discriminating between classes, and the concept of the effective decision boundary is introduced. The proposed feature extraction algorithm has several desirable properties: it predicts the minimum number of features necessary to achieve the same classification accuracy as in the original space for a given pattern recognition problem; and it finds the necessary feature vectors. The proposed algorithm does not deteriorate under the circumstances of equal means or equal covariances as some previous algorithms do. In addition, the decision boundary feature extraction algorithm can be used both for parametric and non-parametric classifiers. Finally, some problems encountered in analyzing high dimensional data are studied and possible solutions are proposed. First, the increased importance of the second order statistics in analyzing high dimensional data is recognized
Mitotic Spindle Disruption by Alternating Electric Fields Leads to Improper Chromosome Segregation and Mitotic Catastrophe in Cancer Cells
Giladi, Moshe; Schneiderman, Rosa S; Voloshin, Tali; Porat, Yaara; Munster, Mijal; Blat, Roni; Sherbo, Shay; Bomzon, Zeev; Urman, Noa; Itzhaki, Aviran; Cahal, Shay; Shteingauz, Anna; Chaudhry, Aafia; Kirson, Eilon D; Weinberg, Uri; Palti, Yoram
Tumor Treating Fields (TTFields) are low intensity, intermediate frequency, alternating electric fields. TTFields are a unique anti-mitotic treatment modality delivered in a continuous, noninvasive manner to the region of a tumor. It was previously postulated that by exerting directional forces on highly polar intracellular elements during mitosis, TTFields could disrupt the normal assembly of spindle microtubules. However there is limited evidence directly linking TTFields to an effect on microtubules. Here we report that TTFields decrease the ratio between polymerized and total tubulin, and prevent proper mitotic spindle assembly. The aberrant mitotic events induced by TTFields lead to abnormal chromosome segregation, cellular multinucleation, and caspase dependent apoptosis of daughter cells. The effect of TTFields on cell viability and clonogenic survival substantially depends upon the cell division rate. We show that by extending the duration of exposure to TTFields, slowly dividing cells can be affected to a similar extent as rapidly dividing cells. PMID:26658786
Prognostic value of mitotic index and Bcl2 expression in male breast cancer.
Lacle, Miangela M; van der Pol, Carmen; Witkamp, Arjen; van der Wall, Elsken; van Diest, Paul J
The incidence of male breast cancer (MBC) is rising. Current treatment regimens for MBC are extrapolated from female breast cancer (FBC), based on the assumption that FBC prognostic features and therapeutic targets can be extrapolated to MBC. However, there is yet little evidence that prognostic features that have been developed and established in FBC are applicable to MBC as well. In a recent study on FBC, a combination of mitotic index and Bcl2 expression proved to be of strong prognostic value. Previous papers on Bcl2 expression in MBC were equivocal, and the prognostic value of Bcl2 combined with mitotic index has not been studied in MBC. The aim of the present study was therefore to investigate the prognostic value of Bcl2 in combination with mitotic index in MBC. Immunohistochemical staining for Bcl2 was performed on tissue microarrays of a total of 151 male breast cancer cases. Mitotic index was scored. The prognostic value of Bcl2 expression and Bcl2/mitotic index combinations was evaluated studying their correlations with clinicopathologic features and their prediction of survival. The vast majority of MBC (94%) showed Bcl2 expression, more frequently than previously described for FBC. Bcl2 expression had no significant associations with clinicopathologic features such as tumor size, mitotic count and grade. In univariate survival analysis, Bcl2 had no prognostic value, and showed no additional prognostic value to tumor size and histological grade in Cox regression. In addition, the Bcl2/mitotic index combination as opposed to FBC did not predict survival in MBC. In conclusion, Bcl2 expression is common in MBC, but is not associated with major clinicopathologic features and, in contrast to FBC, does not seem to have prognostic value, also when combined with mitotic index.
Prognostic comparison of the proliferation markers (mitotic activity index, phosphohistone H3, Ki67), steroid receptors, HER2, high molecular weight cytokeratins and classical prognostic factors in T₁₋₂N₀M₀ breast cancer.
Gudlaugsson, Einar; Klos, Jan; Skaland, Ivar; Janssen, Emiel A M; Smaaland, Rune; Feng, Weiwei; Shao, Zhimin; Malpica, Anais; Baak, Jan P A
The proliferation factors: mitotic activity index (MAI), phosphohistone H3 (PPH3) and Ki67 have strong prognostic value in early breast cancer but their independent value to each other and other prognostic factors has not been evaluated. In 237 T₁₋₂N₀M₀ breast cancers without systemic adjuvant treatment, formalized MAI assessment and strictly standardized, fully automated quantitative immunohistochemistry (IHC) for Ki67, PPH3, estrogen (ER) and progesterone receptor (PR), HER2, cytokeratins-5/6 and -14, and automated digital image analysis (DIA) for measuring PPH3 and Ki67 were performed. Section thickness was measured to further control IHC measurements. All features were measured in the periphery of tumors. The different proliferation assessments and other well-established clinicopathological and biomarker prognostic factors were compared. DIA-Ki67 added prognostically to PPH3. None of the other biomarkers or clinicopathological variables added prognostically to this PPH3/Ki67 combination. However, when PPH3 is replaced by MAI the prognostic value is nearly the same. In early operable node negative breast cancer without adjuvant systemic treatment, Ki67 with a threshold of 6.5% assessed by digital image analysis in the periphery of the tumor is prognostically strong. The combination of either PPH3/Ki67 or MAI/Ki67 overshadowed the prognostic value of all other features including Ki67 alone.
Feature tracking in high-resolution regional climate data
NASA Astrophysics Data System (ADS)
Massey, Neil R.
In this paper, a suite of algorithms are presented which facilitate the identification and tracking of storm-indicative features, such as mean sea-level pressure minima, in high resolution regional climate data. The methods employ a hierarchical triangular mesh, which is tailored to the regional climate data by only subdividing triangles, from an initial icosahedron, within the domain of the data. The regional data is then regridded to this triangular mesh at each level of the grid, producing a compact representation of the data at numerous resolutions. Storm indicative features are detected by first subtracting the background field, represented by a low resolution version of the data, which occurs at a lower level in the mesh. Anomalies from this background field are detected, as feature objects, at a mesh level which corresponds to the spatial scale of the feature being detected and then refined to the highest mesh level. These feature objects are expanded to an outer contour and overlapping objects are merged. The centre points of these objects are tracked across timesteps by applying an optimisation scheme which uses five hierarchical rules. Objects are added to tracks based on the highest rule in the scheme they pass and, if two objects pass the same rule, the cost of adding the object to the track. An object exchange scheme ensures that adding an object to a track is locally optimal. An additional track optimisation phase is performed which exchanges segments between tracks and merges tracks to obtain a globally optimal track set. To validate the suite of algorithms they are applied to the ERA-Interim reanalysis dataset and compared to other storm-indicative feature tracking algorithms.
Microelasticity of Single Mitotic Chromosomes
NASA Astrophysics Data System (ADS)
Poirier, Michael; Eroglu, Sertac; Chatenay, Didier; Marko, John F.; Hirano, Tatsuya
The force-extension behavior of mitotic chromosomes from the newt TVI tumor cell line was studied using micropipette manipulation and force measuring techniques. Reversible, linear elastic response was observed for extensions up to 5 times the native length; the force required to double chromosome length was 1 nanonewton (nN). For further elongations, the linear response teminates at a force plateau of 15 nN and at an extension of 20x. Beyond this extension, the chromosome breaks at elongations between 20x and 70x. These results will be compared to the similar behavior of mitotic chromosomes from explanted newt cells (Poirier, Eroglu, Chatenay and Marko, Mol. Biol. Cell, in press). Also, the effect of biochemical modifications on the elasticity was studied. Ethidium Bromide, which binds to DNA, induces up to a 10 times increase in the Young's modulus. Anti-XCAP-E, which binds to a putative chromosome folding protein, induces up to a 2 times increase in the Young's modulus. Preliminary results on the dynamical relaxation of chromosomes will also be presented. Support of this research through a Biomedical Engineering Research Grant from The Whitaker Foundation is gratefully acknowledged.
Chromatin shapes the mitotic spindle.
Dinarina, Ana; Pugieux, Céline; Corral, Maria Mora; Loose, Martin; Spatz, Joachim; Karsenti, Eric; Nédélec, François
In animal and plant cells, mitotic chromatin locally generates microtubules that self-organize into a mitotic spindle, and its dimensions and bipolar symmetry are essential for accurate chromosome segregation. By immobilizing microscopic chromatin-coated beads on slide surfaces using a microprinting technique, we have examined the effect of chromatin on the dimensions and symmetry of spindles in Xenopus laevis cytoplasmic extracts. While circular spots with diameters around 14-18 microm trigger bipolar spindle formation, larger spots generate an incorrect number of poles. We also examined lines of chromatin with various dimensions. Their length determined the number of poles that formed, with a 6 x 18 microm rectangular patch generating normal spindle morphology. Around longer lines, multiple poles formed and the structures were disorganized. While lines thinner than 10 mum generated symmetric structures, thicker lines induced the formation of asymmetric structures where all microtubules are on the same side of the line. Our results show that chromatin defines spindle shape and orientation. For a video summary of this article, see the PaperFlick file available with the online Supplemental Data.
Feature preserving compression of high resolution SAR images
NASA Astrophysics Data System (ADS)
Yang, Zhigao; Hu, Fuxiang; Sun, Tao; Qin, Qianqing
Compression techniques are required to transmit the large amounts of high-resolution synthetic aperture radar (SAR) image data over the available channels. Common Image compression methods may lose detail and weak information in original images, especially at smoothness areas and edges with low contrast. This is known as "smoothing effect". It becomes difficult to extract and recognize some useful image features such as points and lines. We propose a new SAR image compression algorithm that can reduce the "smoothing effect" based on adaptive wavelet packet transform and feature-preserving rate allocation. For the reason that images should be modeled as non-stationary information resources, a SAR image is partitioned to overlapped blocks. Each overlapped block is then transformed by adaptive wavelet packet according to statistical features of different blocks. In quantifying and entropy coding of wavelet coefficients, we integrate feature-preserving technique. Experiments show that quality of our algorithm up to 16:1 compression ratio is improved significantly, and more weak information is reserved.
On generating cell exemplars for detection of mitotic cells in breast cancer histopathology images.
Aloraidi, Nada A; Sirinukunwattana, Korsuk; Khan, Adnan M; Rajpoot, Nasir M
Mitotic activity is one of the main criteria that pathologists use to decide the grade of the cancer. Computerised mitotic cell detection promises to bring efficiency and accuracy into the grading process. However, detection and classification of mitotic cells in breast cancer histopathology images is a challenging task because of the large intra-class variation in the visual appearance of mitotic cells in various stages of cell division life cycle. In this paper, we test the hypothesis that cells in histopathology images can be effectively represented using cell exemplars derived from sub-images of various kinds of cells in an image for the purposes of mitotic cell classification. We compare three methods for generating exemplar cells. The methods have been evaluated in terms of classification performance on the MITOS dataset. The experimental results demonstrate that eigencells combined with support vector machines produce reasonably high detection accuracy among all the methods.
The nucleoporin ALADIN regulates Aurora A localization to ensure robust mitotic spindle formation
Carvalhal, Sara; Ribeiro, Susana Abreu; Arocena, Miguel; Kasciukovic, Taciana; Temme, Achim; Koehler, Katrin; Huebner, Angela; Griffis, Eric R.
The formation of the mitotic spindle is a complex process that requires massive cellular reorganization. Regulation by mitotic kinases controls this entire process. One of these mitotic controllers is Aurora A kinase, which is itself highly regulated. In this study, we show that the nuclear pore protein ALADIN is a novel spatial regulator of Aurora A. Without ALADIN, Aurora A spreads from centrosomes onto spindle microtubules, which affects the distribution of a subset of microtubule regulators and slows spindle assembly and chromosome alignment. ALADIN interacts with inactive Aurora A and is recruited to the spindle pole after Aurora A inhibition. Of interest, mutations in ALADIN cause triple A syndrome. We find that some of the mitotic phenotypes that we observe after ALADIN depletion also occur in cells from triple A syndrome patients, which raises the possibility that mitotic errors may underlie part of the etiology of this syndrome. PMID:26246606
Learning high-level features for chord recognition using Autoencoder
NASA Astrophysics Data System (ADS)
Phongthongloa, Vilailukkana; Kamonsantiroj, Suwatchai; Pipanmaekaporn, Luepol
Chord transcription is valuable to do by itself. It is known that the manual transcription of chords is very tiresome, time-consuming. It requires, moreover, musical knowledge. Automatic chord recognition has recently attracted a number of researches in the Music Information Retrieval field. It has known that a pitch class profile (PCP) is the commonly signal representation of musical harmonic analysis. However, the PCP may contain additional non-harmonic noise such as harmonic overtones and transient noise. The problem of non-harmonic might be generating the sound energy in term of frequency more than the actual notes of the respective chord. Autoencoder neural network may be trained to learn a mapping from low level feature to one or more higher-level representation. These high-level representations can explain dependencies of the inputs and reduce the effect of non-harmonic noise. Then these improve features are fed into neural network classifier. The proposed high-level musical features show 80.90% of accuracy. The experimental results have shown that the proposed approach can achieve better performance in comparison with other based method.
Regulation of Mitotic Exit in Saccharomyces cerevisiae.
Baro, Bàrbara; Queralt, Ethel; Monje-Casas, Fernando
The Mitotic Exit Network (MEN) is an essential signaling pathway, closely related to the Hippo pathway in mammals, which promotes mitotic exit and initiates cytokinesis in the budding yeast Saccharomyces cerevisiae. Here, we summarize the current knowledge about the MEN components and their regulation.
Precommitment low-level Neurog3 expression defines a long-lived mitotic endocrine-biased progenitor pool that drives production of endocrine-committed cells.
Bechard, Matthew E; Bankaitis, Eric D; Hipkens, Susan B; Ustione, Alessandro; Piston, David W; Yang, Yu-Ping; Magnuson, Mark A; Wright, Christopher V E
The current model for endocrine cell specification in the pancreas invokes high-level production of the transcription factor Neurogenin 3 (Neurog3) in Sox9(+) bipotent epithelial cells as the trigger for endocrine commitment, cell cycle exit, and rapid delamination toward proto-islet clusters. This model posits a transient Neurog3 expression state and short epithelial residence period. We show, however, that a Neurog3(TA.LO) cell population, defined as Neurog3 transcriptionally active and Sox9(+) and often containing nonimmunodetectable Neurog3 protein, has a relatively high mitotic index and prolonged epithelial residency. We propose that this endocrine-biased mitotic progenitor state is functionally separated from a pro-ductal pool and endows them with long-term capacity to make endocrine fate-directed progeny. A novel BAC transgenic Neurog3 reporter detected two types of mitotic behavior in Sox9(+) Neurog3(TA.LO) progenitors, associated with progenitor pool maintenance or derivation of endocrine-committed Neurog3(HI) cells, respectively. Moreover, limiting Neurog3 expression dramatically increased the proportional representation of Sox9(+) Neurog3(TA.LO) progenitors, with a doubling of its mitotic index relative to normal Neurog3 expression, suggesting that low Neurog3 expression is a defining feature of this cycling endocrine-biased state. We propose that Sox9(+) Neurog3(TA.LO) endocrine-biased progenitors feed production of Neurog3(HI) endocrine-committed cells during pancreas organogenesis.
High resolution cloud feature tracking on Venus by Galileo
NASA Technical Reports Server (NTRS)
Toigo, Anthony; Gierasch, Peter J.; Smith, Michael D.
The Venus cloud deck was monitored in February 1990 for 16 hours at 400 nanometers wavelength by the Galileo imaging system, with a spatial resolution of about 15 km and with image time separations as small as 10 minutes. Velocities are deduced by following the motion of small cloud features. In spite of the high temporal frequence is capable of being detected, no dynamical phenomena are apparent in the velocity data except the already well-known solar tides, possibly altered by the slow 4-day wave and the Hadley circulation. There is no evidence, to a level of approximately 4 m/s, of eddy or wavelike activity. The dominant size of sub-global scale albedo features is 200-500 km, and their contrast is approximately 5%. At low altitudes there are patches of blotchy, cell-like structures but at most locations the markings are streaky. The patterns are similar to those discovered by Mariner 10 and Pioneer Venus (M. J. S. Belton et al., 1976, W. B. Rossow et al., 1980). Scaling arguments are presented to argue that the mesoscale blotchy cell-like cloud patterns are caused by local dynamics driven in a shallow layer by differential absorption of sunlight. It is also argued that mesoscale albedo features are either streaky or cell-like simply depending on whether the horizontal shear of the large scale flow exceeds a certain critical value.
Regulation of Aurora-A kinase on the mitotic spindle.
Kufer, Thomas A; Nigg, Erich A; Silljé, Herman H W
The error-free segregation of duplicated chromosomes during cell division is essential for the maintenance of an intact genome. This process is brought about by a highly dynamic bipolar array of microtubules, the mitotic spindle. The formation and function of the mitotic spindle during M-phase of the cell cycle is regulated by protein phosphorylation, involving multiple protein kinases and phosphatases. Prominent among the enzymes implicated in spindle assembly is the serine/threonine-specific protein kinase Aurora-A. In several common human tumors, Aurora-A is overexpressed, and deregulation of this kinase was shown to result in mitotic defects and aneuploidy. Moreover, recent genetic evidence directly links the human Aurora-A gene to cancer susceptibility. Several of the physiological substrates of Aurora-A presumably await identification, but recent studies are beginning to shed light on the regulation of this critical mitotic kinase. Here, we review these findings with particular emphasis on the role of TPX2, a prominent spindle component implicated in a Ran-GTP-mediated spindle assembly pathway.
Aged and post-mitotic cells share a very stable higher-order structure in the cell nucleus in vivo.
Alva-Medina, Janeth; Dent, Myrna A R; Aranda-Anzaldo, Armando
In the mammalian liver the quiescent primary hepatocytes preserve a proliferating potential in vivo, yet natural aging correlates with loss of proliferating potential and progression towards terminal differentiation of the hepatocytes. Thus aged, terminally-differentiated hepatocytes may survive in a de facto post-mitotic state, similarly to early post-mitotic cells, like neurons, suggesting that there might be a common factor linking both cellular states. In the interphase of metazoan cells the nuclear DNA is organized in supercoiled loops anchored to a proteinaceous substructure known as the nuclear matrix (NM). The DNA-NM interactions define a higher-order structure in the cell nucleus (NHOS). Natural aging of the rat liver correlates with a progressive strengthening of the NM framework and the stabilization of the DNA-NM interactions in the hepatocytes indicating that the NHOS becomes highly stable with age. We compared the NHOS of post-mitotic rat neurons with that of aged rat hepatocytes. Our results indicate that a very stable NHOS is a common feature of both aged and post-mitotic cells in vivo.
Features of photoconversion in highly efficient silicon solar cells
Sachenko, A. V.; Shkrebtii, A. I.; Korkishko, R. M.; Kostylyov, V. P.; Kulish, N. R.; Sokolovskyi, I. O.
The photoconversion efficiency η in highly efficient silicon-based solar cells (SCs) is analyzed depending on the total surface-recombination rate S{sub s} on illuminated and rear surfaces. Solar cells based on silicon p-n junctions and α-Si:H or α-SiC:H-Si heterojunctions (so-called HIT structures) are considered in a unified approach. It is shown that a common feature of these SCs is an increased open-circuit voltage V{sub oc} associated with an additional contribution of the rear surface. Within an approach based on analysis of the physical features of photoconversion in SCs, taking into account the main recombination mechanisms, including Shockley-Read-Hall recombination, radiative recombination, surface recombination, recombination in the space-charge region, and band-to-band Auger recombination, expressions for the photoconversion efficiency of such SCs are obtained. The developed theory is compared with experiments, including those for SCs with record parameters, e.g., η = 25% and 24.7% for SCs with a p-n junction for HIT structures, respectively, under AM1.5 conditions. By comparing theory and experiment, the values of S{sub s} achieved as a result of recombination-loss minimization by various methods are determined. The results of calculations of the maximum possible value η{sub max} in silicon SCs are compared with the data of other papers. Good agreement is observed.
Evidence for regulation of mitotic progression through temporal phosphorylation and dephosphorylation of CK2alpha.
St-Denis, Nicole A; Derksen, D Richard; Litchfield, David W
Proper mitotic progression is crucial for maintenance of genomic integrity in proliferating cells and is regulated through an intricate series of events, including protein phosphorylation governed by a complex network of protein kinases. One kinase family implicated in the regulation of mitotic progression is protein kinase CK2, a small family of enzymes that is overexpressed in cancer and induces transformation in mice and cultured fibroblasts. CK2alpha, one isoform of the catalytic subunits of CK2, is maximally phosphorylated at four sites in nocodazole-treated cells. To investigate the effects of CK2alpha phosphorylation on mitotic progression, we generated phosphospecific antibodies against its mitotic phosphorylation sites. In U2OS cells released from S-phase arrest, these antibodies reveal that CK2alpha is most highly phosphorylated in prophase and metaphase. Phosphorylation gradually decreases during anaphase and becomes undetectable during telophase and cytokinesis. Stable expression of phosphomimetic CK2alpha (CK2alpha-4D, CK2alpha-4E) results in aberrant centrosome amplification and chromosomal segregation defects and loss of mitotic cells through mitotic catastrophe. Conversely, cells expressing nonphosphorylatable CK2alpha (CK2alpha-4A) show a decreased ability to arrest in mitosis following nocodazole treatment, suggesting involvement in the spindle assembly checkpoint. Collectively, these studies indicate that reversible phosphorylation of CK2alpha requires precise regulation to allow proper mitotic progression.
Efficient Activation of Apoptotic Signaling during Mitotic Arrest with AK301
Bleiler, Marina; Yeagley, Michelle; Wright, Dennis; Giardina, Charles
Mitotic inhibitors are widely utilized chemotherapeutic agents that take advantage of mitotic defects in cancer cells. We have identified a novel class of piperazine-based mitotic inhibitors, of which AK301 is the most potent derivative identified to date (EC50 < 200 nM). Colon cancer cells arrested in mitosis with AK301 readily underwent a p53-dependent apoptosis following compound withdrawal and arrest release. This apoptotic response was significantly higher for AK301 than for other mitotic inhibitors tested (colchicine, vincristine, and BI 2536). AK301-treated cells exhibited a robust mitosis-associated DNA damage response, including ATM activation, γH2AX phosphorylation and p53 stabilization. The association between mitotic signaling and the DNA damage response was supported by the finding that Aurora B inhibition reduced the level of γH2AX staining. Confocal imaging of AK301-treated cells revealed multiple γ-tubulin microtubule organizing centers attached to microtubules, but with limited centrosome migration, raising the possibility that aberrant microtubule pulling may underlie DNA breakage. AK301 selectively targeted APC-mutant colonocytes and promoted TNF-induced apoptosis in p53-mutant colon cancer cells. Our findings indicate that AK301 induces a mitotic arrest state with a highly active DNA damage response. Together with a reversible arrest state, AK301 is a potent promoter of a mitosis-to-apoptosis transition that can target cancer cells with mitotic defects. PMID:27097159
Distinct Kinesin-14 mitotic mechanisms in spindle bipolarity.
Simeonov, Dimitre R; Kenny, Katelyn; Seo, Lan; Moyer, Amanda; Allen, Jessica; Paluh, Janet L
Kinesin-like proteins are integral to formation and function of a conserved mitotic spindle apparatus that directs chromosome segregation and precedes cell division. Ubiquitous to the mechanism of spindle assembly and stability are balanced Kinesin-5 promoting and Kinesin-14 opposing forces. Distinct Kinesin-14 roles in bipolarity in eukaryotes have not been shown, but are suggested by gamma-tubulin-based pole interactions that affect establishment and by microtubule cross-linking and sliding that maintain bipolarity and spindle length. Distinct roles also imply specialized functional domains. By cross-species analysis of compatible mechanisms in establishing mitotic bipolarity we demonstrate that Kinesin-14 human HSET (HsHSET) functionally replaces Schizosaccharomyces pombe Pkl1 and its action is similarly blocked by mutation in a Kinesin-14 binding site on gamma-tubulin. Drosophila DmNcd localizes preferentially to bundled interpolar microtubules in fission yeast and does not replace SpPkl1. Analysis of twenty-six Kinesin-14 derivatives, including Tail, Stalk or Neck-Motor chimeras, for spindle localization, spindle assembly and mitotic progression defined critical domains. The Tail of SpPkl1 contains functional elements enabling its role in spindle assembly that are distinct from but transferable to DmNcd, whereas HsHSET function utilizes both Tail and Stalk features. Our analysis is the first to demonstrate distinct mechanisms between SpPkl1 and DmNcd, and reveal that HsHSET shares functional overlap in spindle pole mechanisms.
On the molecular mechanisms of mitotic kinase activation
Bayliss, Richard; Fry, Andrew; Haq, Tamanna; Yeoh, Sharon
During mitosis, human cells exhibit a peak of protein phosphorylation that alters the behaviour of a significant proportion of proteins, driving a dramatic transformation in the cell's shape, intracellular structures and biochemistry. These mitotic phosphorylation events are catalysed by several families of protein kinases, including Auroras, Cdks, Plks, Neks, Bubs, Haspin and Mps1/TTK. The catalytic activities of these kinases are activated by phosphorylation and through protein–protein interactions. In this review, we summarize the current state of knowledge of the structural basis of mitotic kinase activation mechanisms. This review aims to provide a clear and comprehensive primer on these mechanisms to a broad community of researchers, bringing together the common themes, and highlighting specific differences. Along the way, we have uncovered some features of these proteins that have previously gone unreported, and identified unexplored questions for future work. The dysregulation of mitotic kinases is associated with proliferative disorders such as cancer, and structural biology will continue to play a critical role in the development of chemical probes used to interrogate disease biology and applied to the treatment of patients. PMID:23226601
On the molecular mechanisms of mitotic kinase activation.
Bayliss, Richard; Fry, Andrew; Haq, Tamanna; Yeoh, Sharon
During mitosis, human cells exhibit a peak of protein phosphorylation that alters the behaviour of a significant proportion of proteins, driving a dramatic transformation in the cell's shape, intracellular structures and biochemistry. These mitotic phosphorylation events are catalysed by several families of protein kinases, including Auroras, Cdks, Plks, Neks, Bubs, Haspin and Mps1/TTK. The catalytic activities of these kinases are activated by phosphorylation and through protein-protein interactions. In this review, we summarize the current state of knowledge of the structural basis of mitotic kinase activation mechanisms. This review aims to provide a clear and comprehensive primer on these mechanisms to a broad community of researchers, bringing together the common themes, and highlighting specific differences. Along the way, we have uncovered some features of these proteins that have previously gone unreported, and identified unexplored questions for future work. The dysregulation of mitotic kinases is associated with proliferative disorders such as cancer, and structural biology will continue to play a critical role in the development of chemical probes used to interrogate disease biology and applied to the treatment of patients.
Profiling DNA damage response following mitotic perturbations
S. Pedersen, Ronni; Karemore, Gopal; Gudjonsson, Thorkell; Rask, Maj-Britt; Neumann, Beate; Hériché, Jean-Karim; Pepperkok, Rainer; Ellenberg, Jan; Gerlich, Daniel W.; Lukas, Jiri; Lukas, Claudia
Genome integrity relies on precise coordination between DNA replication and chromosome segregation. Whereas replication stress attracted much attention, the consequences of mitotic perturbations for genome integrity are less understood. Here, we knockdown 47 validated mitotic regulators to show that a broad spectrum of mitotic errors correlates with increased DNA breakage in daughter cells. Unexpectedly, we find that only a subset of these correlations are functionally linked. We identify the genuine mitosis-born DNA damage events and sub-classify them according to penetrance of the observed phenotypes. To demonstrate the potential of this resource, we show that DNA breakage after cytokinesis failure is preceded by replication stress, which mounts during consecutive cell cycles and coincides with decreased proliferation. Together, our results provide a resource to gauge the magnitude and dynamics of DNA breakage associated with mitotic aberrations and suggest that replication stress might limit propagation of cells with abnormal karyotypes. PMID:27976684
High-velocity features in Type Ia supernova spectra
NASA Astrophysics Data System (ADS)
Childress, Michael J.; Filippenko, Alexei V.; Ganeshalingam, Mohan; Schmidt, Brian P.
We use a sample of 58 low-redshift (z ≤ 0.03) Type Ia supernovae (SNe Ia) having well-sampled light curves and spectra near maximum light to examine the behaviour of high-velocity features (HVFs) in SN Ia spectra. We take advantage of the fact that Si II λ6355 is free of HVFs at maximum light in all SNe Ia, while HVFs are still strong in the Ca II near-infrared feature in many SNe, allowing us to quantify the strength of HVFs by comparing the structure of these two lines. We find that the average HVF strength increases with decreasing light-curve decline rate, and rapidly declining SNe Ia (Δm15(B) ≥ 1.4 mag) show no HVFs in their maximum-light spectra. Comparison of HVF strength to the light-curve colour of the SNe Ia in our sample shows no evidence of correlation. We find a correlation of HVF strength with the velocity of Si II λ6355 at maximum light (vSi), such that SNe Ia with lower vSi have stronger HVFs, while those SNe Ia firmly in the `high-velocity' (i.e. vSi ≥ 12 000 km s-1) subclass exhibit no HVFs in their maximum-light spectra. While vSi and Δm15(B) show no correlation in the full sample of SNe Ia, we find a significant correlation between these quantities in the subset of SNe Ia having weak HVFs. In general, we find that slowly declining (low Δm15(B)) SNe Ia, which are more luminous and more energetic than average SNe Ia, tend to produce either high photospheric ejecta velocities (i.e. high vSi) or strong HVFs at maximum light, but not both. Finally, we examine the evolution of HVF strength for a sample of SNe Ia having extensive pre-maximum spectroscopic coverage and find significant diversity of the pre-maximum HVF behaviour.
High-Throughput Quantification of Phenotype Heterogeneity Using Statistical Features
Chaddad, Ahmad; Tanougast, Camel
Statistical features are widely used in radiology for tumor heterogeneity assessment using magnetic resonance (MR) imaging technique. In this paper, feature selection based on decision tree is examined to determine the relevant subset of glioblastoma (GBM) phenotypes in the statistical domain. To discriminate between active tumor (vAT) and edema/invasion (vE) phenotype, we selected the significant features using analysis of variance (ANOVA) with p value < 0.01. Then, we implemented the decision tree to define the optimal subset features of phenotype classifier. Naïve Bayes (NB), support vector machine (SVM), and decision tree (DT) classifier were considered to evaluate the performance of the feature based scheme in terms of its capability to discriminate vAT from vE. Whole nine features were statistically significant to classify the vAT from vE with p value < 0.01. Feature selection based on decision tree showed the best performance by the comparative study using full feature set. The feature selected showed that the two features Kurtosis and Skewness achieved a highest range value of 58.33–75.00% accuracy classifier and 73.88–92.50% AUC. This study demonstrated the ability of statistical features to provide a quantitative, individualized measurement of glioblastoma patient and assess the phenotype progression. PMID:26640485
Radar-anomalous, high-altitude features on Venus
NASA Technical Reports Server (NTRS)
Muhleman, Duane O.; Butler, Bryan J.
Over nearly all of the surface of Venus the reflectivity and emissivity at centimeter wavelengths are about 0.15 and 0.85 respectively. These values are consistent with moderately dense soils and rock populations, but the mean reflectivity is about a factor of 2 greater than that for the Moon and other terrestrial planets. Pettingill and Ford, using Pioneer Venus reflectivities and emissivities, found a number of anomalous features on Venus that showed much higher reflectivities and much lower emissivities with both values approaching 0.5. These include Maxwell Montes, a number of high regions in Aphrodite Terra and Beta Regio, and several isolated mountain peaks. Most of the features are at altitudes above the mean radius by 2 to 3 km or more. However, such features have been found in the Magellan data at low altitudes and the anomalies do not exist on all high structures, Maat Mons being the most outstanding example. A number of papers have been written that attempt to explain the phenomena in terms of the geochemistry balance of weathering effects on likely surface minerals. The geochemists have shown that the fundamentally basaltic surface would be stable at the temperatures and pressures of the mean radius in the form of magnetite, but would evolve to pyrite and/or pyrrhotite in the presence of sulfur-bearing compounds such as SO2. Pyrite will be stable at altitudes above 4 or 5 km on Venus. Although the geochemical arguments are rather compelling, it is vitally important to rationally look at other explanations for radar and radio emission measurements such as that presented by Tryka and Muhleman. The radar reflectivity values are retrieved from the raw Magellan backscatter measurements by fitting the Hagfors' radar scattering model in which a surface roughness parameters and a normal incidence electrical reflectivity are estimated. The assumptions of the theory behind the model must be considered carefully before the results can be believed. These include
Physical determinants of bipolar mitotic spindle assembly and stability in fission yeast
Blackwell, Robert; Edelmaier, Christopher; Sweezy-Schindler, Oliver; Lamson, Adam; Gergely, Zachary R.; O'Toole, Eileen; Crapo, Ammon; Hough, Loren E.; McIntosh, J. Richard; Glaser, Matthew A.; Betterton, Meredith D.
Mitotic spindles use an elegant bipolar architecture to segregate duplicated chromosomes with high fidelity. Bipolar spindles form from a monopolar initial condition; this is the most fundamental construction problem that the spindle must solve. Microtubules, motors, and cross-linkers are important for bipolarity, but the mechanisms necessary and sufficient for spindle assembly remain unknown. We describe a physical model that exhibits de novo bipolar spindle formation. We began with physical properties of fission-yeast spindle pole body size and microtubule number, kinesin-5 motors, kinesin-14 motors, and passive cross-linkers. Our model results agree quantitatively with our experiments in fission yeast, thereby establishing a minimal system with which to interrogate collective self-assembly. By varying the features of our model, we identify a set of functions essential for the generation and stability of spindle bipolarity. When kinesin-5 motors are present, their bidirectionality is essential, but spindles can form in the presence of passive cross-linkers alone. We also identify characteristic failed states of spindle assembly—the persistent monopole, X spindle, separated asters, and short spindle, which are avoided by the creation and maintenance of antiparallel microtubule overlaps. Our model can guide the identification of new, multifaceted strategies to induce mitotic catastrophes; these would constitute novel strategies for cancer chemotherapy. PMID:28116355
Mitotic exit: Determining the PP2A dephosphorylation program.
Pereira, Gislene; Schiebel, Elmar
In mitotic exit, proteins that were highly phosphorylated are sequentially targeted by the phosphatase PP2A-B55, but what underlies substrate selection is unclear. In this issue, Cundell et al. (2016. J. Cell Biol http://dx.doi.org/10.1083/jcb.201606033) identify the determinants of PP2A-B55's dephosphorylation program, thereby influencing spindle disassembly, nuclear envelope reformation, and cytokinesis.
Mitotic exit: Determining the PP2A dephosphorylation program
In mitotic exit, proteins that were highly phosphorylated are sequentially targeted by the phosphatase PP2A-B55, but what underlies substrate selection is unclear. In this issue, Cundell et al. (2016. J. Cell Biol. http://dx.doi.org/10.1083/jcb.201606033) identify the determinants of PP2A-B55's dephosphorylation program, thereby influencing spindle disassembly, nuclear envelope reformation, and cytokinesis. PMID:27551057
A comprehensive model to predict mitotic division in budding yeasts
Sutradhar, Sabyasachi; Yadav, Vikas; Sridhar, Shreyas; Sreekumar, Lakshmi; Bhattacharyya, Dibyendu; Ghosh, Santanu Kumar; Paul, Raja; Sanyal, Kaustuv
High-fidelity chromosome segregation during cell division depends on a series of concerted interdependent interactions. Using a systems biology approach, we built a robust minimal computational model to comprehend mitotic events in dividing budding yeasts of two major phyla: Ascomycota and Basidiomycota. This model accurately reproduces experimental observations related to spindle alignment, nuclear migration, and microtubule (MT) dynamics during cell division in these yeasts. The model converges to the conclusion that biased nucleation of cytoplasmic microtubules (cMTs) is essential for directional nuclear migration. Two distinct pathways, based on the population of cMTs and cortical dyneins, differentiate nuclear migration and spindle orientation in these two phyla. In addition, the model accurately predicts the contribution of specific classes of MTs in chromosome segregation. Thus we present a model that offers a wider applicability to simulate the effects of perturbation of an event on the concerted process of the mitotic cell division. PMID:26310442
Mitotic noncoding RNA processing promotes kinetochore and spindle assembly in Xenopus
Grenfell, Andrew W.
Transcription at the centromere of chromosomes plays an important role in kinetochore assembly in many eukaryotes, and noncoding RNAs contribute to activation of the mitotic kinase Aurora B. However, little is known about how mitotic RNA processing contributes to spindle assembly. We found that inhibition of transcription initiation or RNA splicing, but not translation, leads to spindle defects in Xenopus egg extracts. Spliceosome inhibition resulted in the accumulation of high molecular weight centromeric transcripts, concomitant with decreased recruitment of the centromere and kinetochore proteins CENP-A, CENP-C, and NDC80 to mitotic chromosomes. In addition, blocking transcript synthesis or processing during mitosis caused accumulation of MCAK, a microtubule depolymerase, on the spindle, indicating misregulation of Aurora B. These findings suggest that co-transcriptional recruitment of the RNA processing machinery to nascent mitotic transcripts is an important step in kinetochore and spindle assembly and challenge the idea that RNA processing is globally repressed during mitosis. PMID:27402954
Micromechanical study of mitotic chromosome structure
NASA Astrophysics Data System (ADS)
Marko, John
Our group has developed micromanipulation techniques for study of the highly compacted mitotic form of chromosome found in eukaryote cells during cell division. Each metaphase chromosome contains two duplicate centimeter-long DNA molecules, folded up by proteins into cylindrical structures several microns in length. Native chromosomes display linear and reversible stretching behavior over a wide range of extensions (up to 5x native length for amphibian chromosomes), described by a Young modulus of about 300 Pa. Studies using DNA-cutting and protein-cutting enzymes have revealed that metaphase chromosomes behave as a network of chromatin fibers held together by protein-based isolated crosslinks. Our results are not consistent with the more classical model of loops of chromatin attached to a protein-based structural organizer or ``scaffold". In short, our experiments indicate that metaphase chromosomes can be considered to be ``gels" of chromatin; the stretching modulus of a whole chromosome is consistent with stretching of the chromatin fibers contained within it. Experiments using topoisomerases suggest that topological constraints may play an appreciable role in confining chromatin in the metaphase chromosome. Finally, recent experiments on human chromosomes will be reviewed, including results of experiments where chromosome-folding proteins are specifically depleted using siRNA methods. Supported by NSF-MCB-1022117, DMR-0715099, PHY-0852130, DMR-0520513, NCI 1U54CA143869-01 (NU-PS-OC), and the American Heart Association.
Toward a systems-level view of mitotic checkpoints.
Ibrahim, Bashar
Reproduction and natural selection are the key elements of life. In order to reproduce, the genetic material must be doubled, separated and placed into two new daughter cells, each containing a complete set of chromosomes and organelles. In mitosis, transition from one process to the next is guided by intricate surveillance mechanisms, known as the mitotic checkpoints. Dis-regulation of cell division through checkpoint malfunction can lead to developmental defects and contribute to the development or progression of tumors. This review approaches two important mitotic checkpoints, the spindle assembly checkpoint (SAC) and the spindle position checkpoint (SPOC). The highly conserved spindle assembly checkpoint (SAC) controls the onset of anaphase by preventing premature segregation of the sister chromatids of the duplicated genome, to the spindle poles. In contrast, the spindle position checkpoint (SPOC), in the budding yeast Saccharomyces cerevisiae, ensures that during asymmetric cell division mitotic exit does not occur until the spindle is properly aligned with the cell polarity axis. Although there are no known homologs, there is indication that functionally similar checkpoints exist also in animal cells. This review can be regarded as an "executable model", which could be easily translated into various quantitative concrete models like Petri nets, ODEs, PDEs, or stochastic particle simulations. It can also function as a base for developing quantitative models explaining the interplay of the various components and proteins controlling mitosis.
High Resolution Urban Feature Extraction for Global Population Mapping using High Performance Computing
Vijayaraj, Veeraraghavan; Bright, Eddie A; Bhaduri, Budhendra L
The advent of high spatial resolution satellite imagery like Quick Bird (0.6 meter) and IKONOS (1 meter) has provided a new data source for high resolution urban land cover mapping. Extracting accurate urban regions from high resolution images has many applications and is essential to the population mapping efforts of Oak Ridge National Laboratory's (ORNL) LandScan population distribution program. This paper discusses an automated parallel algorithm that has been implemented on a high performance computing environment to extract urban regions from high resolution images using texture and spectral features
Pretreatment in a high-pressure microwave processor for MIB-1 immunostaining of cytological smears and paraffin tissue sections to visualize the various phases of the mitotic cycle.
Suurmeijer, A J; Boon, M E
In many pathology laboratories, both microwave ovens and pressure cookers are used for pretreatment of cytologic smears and paraffin sections to allow MIB-1 staining. For both methods there are two problems. First, the results cannot be used for quantitation because standardization is impossible. Second, the staining results are often suboptimal, resulting in negative staining of cells in the G(1)- and S-phases. When pretreatment is performed in a microwave processor, allowing microwave heating under pressure, precise temperature monitoring becomes possible. In addition, the importance of the pH of the buffer was studied using a test battery series. Optimal staining is achieved at a temperature of 115C, 10 min, pH 6. This method proved to be highly reproducible. Because the immunostaining results are optimal, the various phases of the cell cycle can be defined in the sections and smears. In addition, the perinucleolar staining of the late G(1)-phase is optimally visualized and nuclei of the stable pKi-67 pathway can be identified. Under suboptimal conditions, in particular, the number of cells in the late G(1)-phase are underestimated in the MIB-1 counts.
Epigenetic countermarks in mitotic chromosome condensation.
van Wely, Karel H M; Mora Gallardo, Carmen; Vann, Kendra R; Kutateladze, Tatiana G
Mitosis in metazoans is characterized by abundant phosphorylation of histone H3 and involves the recruitment of condensin complexes to chromatin. The relationship between the 2 phenomena and their respective contributions to chromosome condensation in vivo remain poorly understood. Recent studies have shown that H3T3 phosphorylation decreases binding of histone readers to methylated H3K4 in vitro and is essential to displace the corresponding proteins from mitotic chromatin in vivo. Together with previous observations, these data provide further evidence for a role of mitotic histone H3 phosphorylation in blocking transcriptional programs or preserving the 'memory' PTMs. Mitotic protein exclusion can also have a role in depopulating the chromatin template for subsequent condensin loading. H3 phosphorylation thus serves as an integral step in the condensation of chromosome arms.
The mitotic spindle and actin tails.
Karsenti, Eric; Nédélec, François
To segregate their chromosomes, eukaryotic cells rely on a dynamic structure made of microtubules: the mitotic spindle. This structure can form in cells lacking centrosomes, because their chromosomes also nucleate microtubules. This second assembly pathway is observed even in some cells that naturally have centrosomes, for example when the centrosomes are ablated by laser surgery. Recent results have started to address the complementary question of whether centrosome-nucleated microtubules alone could sustain the formation of a functional mitotic spindle. We wonder in this respect whether lower eukaryotes such as yeasts are different from higher eukaryotes such as vertebrates.
Mazia, Daniel; Mitchison, J. M.; Medina, Heitor; Harris, Patricia
A method for isolating the mitotic apparatus from dividing sea urchin eggs without the use of ethyl alcohol or of detergents is described. In the present method, the eggs are dispersed directly in a medium containing 1 M (to 1.15 M) sucrose, 0.15 M dithiodiglycol, and 0.001 M Versene at pH 6, releasing the visibly intact mitotic apparatus. The method is designed for studies of enzyme activities, lipid components, and the variables affecting the stability of the apparatus. PMID:13768661
Feature Extraction of High-Dimensional Structures for Exploratory Analytics
development of a method to gain insight into HDD, particularly in the application of an analytic strategy to terrorist data. 15. SUBJECT TERMS...geodesic distance 4 (8); (3) the COIL-20 dataset; (4) word-features dataset; and (5) a Netflix dataset.* Although the manifold learners are
Rapid measurement of mitotic spindle orientation in cultured mammalian cells
Decarreau, Justin; Driver, Jonathan; Asbury, Charles; Wordeman, Linda
Summary Factors that influence the orientation of the mitotic spindle are important for the maintenance of stem cell populations and in cancer development. However, screening for these factors requires rapid quantification of alterations of the angle of the mitotic spindle in cultured cell lines. Here we describe a method to image mitotic cells and rapidly score the angle of the mitotic spindle using a simple MATLAB application to analyze a stack of Z-images. PMID:24633791
Bibring, Thomas; Baxandall, Jane
Mitotic apparatus isolated from sea urchin eggs has been treated with meralluride sodium under conditions otherwise resembling those of its isolation. The treatment causes a selective morphological disappearance of microtubules while extracting a major protein fraction, probably consisting of two closely related proteins, which constitutes about 10% of mitotic apparatus protein. Extraction of other cell particulates under similar conditions yields much less of this protein. The extracted protein closely resembles outer doublet microtubule protein from sea urchin sperm tail in properties considered typical of microtubule proteins: precipitation by calcium ion and vinblastine, electrophoretic mobility in both acid and basic polyacrylamide gels, sedimentation coefficient, molecular weight, and, according to a preliminary determination, amino acid composition. An antiserum against a preparation of sperm tail outer doublet microtubules cross-reacts with the extract from mitotic apparatus. On the basis of these findings it appears that microtubule protein is selectively extracted from isolated mitotic apparatus by treatment with meralluride, and is a typical microtubule protein. PMID:5543404
Mitotic figure counts are significantly overestimated in resection specimens of invasive breast carcinomas.
Lehr, Hans-Anton; Rochat, Candice; Schaper, Cornelia; Nobile, Antoine; Shanouda, Sherien; Vijgen, Sandrine; Gauthier, Arnaud; Obermann, Ellen; Leuba, Susana; Schmidt, Marcus; C, Curzio Ruegg; Delaloye, Jean-Francois; Simiantonaki, Nectaria; Schaefer, Stephan C
Several authors have demonstrated an increased number of mitotic figures in breast cancer resection specimen when compared with biopsy material. This has been ascribed to a sampling artifact where biopsies are (i) either too small to allow formal mitotic figure counting or (ii) not necessarily taken form the proliferating tumor periphery. Herein, we propose a different explanation for this phenomenon. Biopsy and resection material of 52 invasive ductal carcinomas was studied. We counted mitotic figures in 10 representative high power fields and quantified MIB-1 immunohistochemistry by visual estimation, counting and image analysis. We found that mitotic figures were elevated by more than three-fold on average in resection specimen over biopsy material from the same tumors (20±6 vs 6±2 mitoses per 10 high power fields, P=0.008), and that this resulted in a relative diminution of post-metaphase figures (anaphase/telophase), which made up 7% of all mitotic figures in biopsies but only 3% in resection specimen (P<0.005). At the same time, the percentages of MIB-1 immunostained tumor cells among total tumor cells were comparable in biopsy and resection material, irrespective of the mode of MIB-1 quantification. Finally, we found no association between the size of the biopsy material and the relative increase of mitotic figures in resection specimen. We propose that the increase in mitotic figures in resection specimen and the significant shift towards metaphase figures is not due to a sampling artifact, but reflects ongoing cell cycle activity in the resected tumor tissue due to fixation delay. The dwindling energy supply will eventually arrest tumor cells in metaphase, where they are readily identified by the diagnostic pathologist. Taken together, we suggest that the rapidly fixed biopsy material better represents true tumor biology and should be privileged as predictive marker of putative response to cytotoxic chemotherapy.
A highly invasive subpopulation of MDA-MB-231 breast cancer cells shows accelerated growth, differential chemoresistance, features of apocrine tumors and reduced tumorigenicity in vivo
Mirisola, Valentina; Esposito, Alessia Isabella; Reverberi, Daniele; Matis, Serena; Maffei, Massimo; Giaretti, Walter; Viale, Maurizio; Gangemi, Rosaria; Emionite, Laura; Astigiano, Simonetta; Cilli, Michele; Bachmeier, Beatrice E.; Killian, Peter H.; Albini, Adriana; Pfeffer, Ulrich
The acquisition of an invasive phenotype is a prerequisite for metastasization, yet it is not clear whether or to which extent the invasive phenotype is linked to other features characteristic of metastatic cells. We selected an invasive subpopulation from the triple negative breast cancer cell line MDA-MB-231, performing repeated cycles of preparative assays of invasion through Matrigel covered membranes. The invasive sub-population of MDA-MB-231 cells exhibits stronger migratory capacity as compared to parental cells confirming the highly invasive potential of the selected cell line. Prolonged cultivation of these cells did not abolish the invasive phenotype. ArrayCGH, DNA index quantification and karyotype analyses confirmed a common genetic origin of the parental and invasive subpopulations and revealed discrete structural differences of the invasive subpopulation including increased ploidy and the absence of a characteristic amplification of chromosome 5p14.1-15.33. Gene expression analyses showed a drastically altered expression profile including features of apocrine breast cancers and of invasion related matrix-metalloproteases and cytokines. The invasive cells showed accelerated proliferation, increased apoptosis, and an altered pattern of chemo-sensitivity with lower IC50 values for drugs affecting the mitotic apparatus. However, the invasive cell population is significantly less tumorigenic in orthotopic mouse xenografts suggesting that the acquisition of the invasive capacity and the achievement of metastatic growth potential are distinct events. PMID:27626697
Prolonged oestrogen treatment does not correlate with a sustained increase in anterior pituitary mitotic index in ovariectomized Wistar rats.
Nolan, L A; Levy, A
Oestrogen is a powerful mitogen that is believed to exert a continuous, dose-dependent trophic stimulus at the anterior pituitary. This persistent mitotic effect contrasts with corticosterone and testosterone, changes in the levels of which induce only transient, self-limiting fluctuations in pituitary mitotic activity. To further define the putative long-term trophic effects of oestrogen, we have accurately analysed the effects of 7 and 28 days oestrogen treatment on anterior pituitary mitotic activity in ovariectomized 10-week-old Wistar rats using both bromodeoxyuridine (BrdU) and timed colchicine-induced mitotic arrest. An oestrogen dose-dependent increase in mitotic index was seen 7 days after the start of treatment as expected, representing an acceleration in gross mitotic activity from 1.7%/day in ovariectomized animals in the absence of any oestrogen replacement to 3.7%/day in the presence of a pharmacological dose of oestrogen (50 mcg/rat per day: approximately 230 mcg/kg per day). Despite continued exposure to high-dose oestrogen and persistence of the increase in pituitary wet weight, the increase in mitotic index was unexpectedly not sustained. After 28 days of high-dose oestrogen treatment, anterior pituitary mitotic index and BrdU-labelling index were not significantly different from baseline. Although a powerful pituitary mitogen in the short term, responsible, presumably, for increased trophic variability in oestrus cycling females, these data indicate that in keeping with other trophic stimuli to the pituitary and in contrast to a much established dogma, the mitotic response to longer-term high-dose oestrogen exposure is transient and is not the driver of persistent pituitary growth, at least in female Wistar rats.
A Functional Mitotic Spindle Prepared from Mammalian Cells in Culture
Cande, W. Zacheus; Snyder, Judith; Smith, Diana; Summers, Keith; McIntosh, J. R.
Mitotic cells lysed into solutions of polymerizable microtubule protein contain a spindle which is similar to the living spindle in two respects: it will lose and gain birefringence when cooled and warmed, and it will move anaphase chromosomes to the opposite ends of the cell. Early anaphase cells lysed into buffers containing high molecular weight polyethylene glycol and nucleotide triphosphates will continue chromosome motion and spindle elongation in the absence of exogenous spindle subunits. These results suggest that while spindle growth requires microtubule polymerization, anaphase motions do not. Images PMID:4524659
Evidence of Selection against Complex Mitotic-Origin Aneuploidy during Preimplantation Development
McCoy, Rajiv C.; Demko, Zachary P.; Ryan, Allison; Banjevic, Milena; Hill, Matthew; Sigurjonsson, Styrmir; Rabinowitz, Matthew; Petrov, Dmitri A.
Whole-chromosome imbalances affect over half of early human embryos and are the leading cause of pregnancy loss. While these errors frequently arise in oocyte meiosis, many such whole-chromosome abnormalities affecting cleavage-stage embryos are the result of chromosome missegregation occurring during the initial mitotic cell divisions. The first wave of zygotic genome activation at the 4–8 cell stage results in the arrest of a large proportion of embryos, the vast majority of which contain whole-chromosome abnormalities. Thus, the full spectrum of meiotic and mitotic errors can only be detected by sampling after the initial cell divisions, but prior to this selective filter. Here, we apply 24-chromosome preimplantation genetic screening (PGS) to 28,052 single-cell day-3 blastomere biopsies and 18,387 multi-cell day-5 trophectoderm biopsies from 6,366 in vitro fertilization (IVF) cycles. We precisely characterize the rates and patterns of whole-chromosome abnormalities at each developmental stage and distinguish errors of meiotic and mitotic origin without embryo disaggregation, based on informative chromosomal signatures. We show that mitotic errors frequently involve multiple chromosome losses that are not biased toward maternal or paternal homologs. This outcome is characteristic of spindle abnormalities and chaotic cell division detected in previous studies. In contrast to meiotic errors, our data also show that mitotic errors are not significantly associated with maternal age. PGS patients referred due to previous IVF failure had elevated rates of mitotic error, while patients referred due to recurrent pregnancy loss had elevated rates of meiotic error, controlling for maternal age. These results support the conclusion that mitotic error is the predominant mechanism contributing to pregnancy losses occurring prior to blastocyst formation. This high-resolution view of the full spectrum of whole-chromosome abnormalities affecting early embryos provides insight
Arsenite-induced mitotic death involves stress response and is independent of tubulin polymerization
Taylor, B. Frazier; McNeely, Samuel C.; Miller, Heather L.; States, J. Christopher
Arsenite, a known mitotic disruptor, causes cell cycle arrest and cell death at anaphase. The mechanism causing mitotic arrest is highly disputed. We compared arsenite to the spindle poisons nocodazole and paclitaxel. Immunofluorescence analysis of {alpha}-tubulin in interphase cells demonstrated that, while nocodazole and paclitaxel disrupt microtubule polymerization through destabilization and hyperpolymerization, respectively, microtubules in arsenite-treated cells remain comparable to untreated cells even at supra-therapeutic concentrations. Immunofluorescence analysis of {alpha}-tubulin in mitotic cells showed spindle formation in arsenite- and paclitaxel-treated cells but not in nocodazole-treated cells. Spindle formation in arsenite-treated cells appeared irregular and multi-polar. {gamma}-tubulin staining showed that cells treated with nocodazole and therapeutic concentrations of paclitaxel contained two centrosomes. In contrast, most arsenite-treated mitotic cells contained more than two centrosomes, similar to centrosome abnormalities induced by heat shock. Of the three drugs tested, only arsenite treatment increased expression of the inducible isoform of heat shock protein 70 (HSP70i). HSP70 and HSP90 proteins are intimately involved in centrosome regulation and mitotic spindle formation. HSP90 inhibitor 17-DMAG sensitized cells to arsenite treatment and increased arsenite-induced centrosome abnormalities. Combined treatment of 17-DMAG and arsenite resulted in a supra-additive effect on viability, mitotic arrest, and centrosome abnormalities. Thus, arsenite-induced abnormal centrosome amplification and subsequent mitotic arrest is independent of effects on tubulin polymerization and may be due to specific stresses that are protected against by HSP90 and HSP70.
Emission features in the spectrum of NGC 7027 near 3. 3 microns at very high resolution
Lowe, R.P.; Moorhead, J.M.; Wehlau, W.H.; Maillard, J.P. CNRS, Institut d'Astrophysique, Paris )
A very high resolution spectrum is presented of the planetary nebula NGC 7027 over a 200/cm interval centered at 2950/cm, and the features found are described: (1) nebular continuum, (2) atomic recombination lines of H and He II, and (3) three broader emission features of uncertain origin. For the latter the first evidence is presented that the 3.46 micron feature and possibly the 3.40 micron feature are resolvable into a sequence of narrower features. The interpretation of the broader features is discussed in terms of the hypothesis of identification with emission by polycyclic aromatic hydrocarbons. 18 refs.
Evidence for Regulation of Mitotic Progression through Temporal Phosphorylation and Dephosphorylation of CK2α▿ †
St-Denis, Nicole A.; Derksen, D. Richard; Litchfield, David W.
Proper mitotic progression is crucial for maintenance of genomic integrity in proliferating cells and is regulated through an intricate series of events, including protein phosphorylation governed by a complex network of protein kinases. One kinase family implicated in the regulation of mitotic progression is protein kinase CK2, a small family of enzymes that is overexpressed in cancer and induces transformation in mice and cultured fibroblasts. CK2α, one isoform of the catalytic subunits of CK2, is maximally phosphorylated at four sites in nocodazole-treated cells. To investigate the effects of CK2α phosphorylation on mitotic progression, we generated phosphospecific antibodies against its mitotic phosphorylation sites. In U2OS cells released from S-phase arrest, these antibodies reveal that CK2α is most highly phosphorylated in prophase and metaphase. Phosphorylation gradually decreases during anaphase and becomes undetectable during telophase and cytokinesis. Stable expression of phosphomimetic CK2α (CK2α-4D, CK2α-4E) results in aberrant centrosome amplification and chromosomal segregation defects and loss of mitotic cells through mitotic catastrophe. Conversely, cells expressing nonphosphorylatable CK2α (CK2α-4A) show a decreased ability to arrest in mitosis following nocodazole treatment, suggesting involvement in the spindle assembly checkpoint. Collectively, these studies indicate that reversible phosphorylation of CK2α requires precise regulation to allow proper mitotic progression. PMID:19188443
Oncogenic KRAS triggers MAPK-dependent errors in mitosis and MYC-dependent sensitivity to anti-mitotic agents
Perera, David; Venkitaraman, Ashok R.
Oncogenic KRAS induces cell proliferation and transformation, but little is known about its effects on cell division. Functional genetic screens have recently revealed that cancer cell lines expressing oncogenic KRAS are sensitive to interference with mitosis, but neither the mechanism nor the uniformity of anti-mitotic drug sensitivity connected with mutant KRAS expression are yet clear. Here, we report that acute expression of oncogenic KRAS in HeLa cells induces mitotic delay and defects in chromosome segregation through mitogen-activated protein kinase (MAPK) pathway activation and de-regulated expression of several mitosis-related genes. These anomalies are accompanied by increased sensitivity to anti-mitotic agents, a phenotype dependent on the transcription factor MYC and its downstream target anti-apoptotic protein BCL-XL. Unexpectedly, we find no correlation between KRAS mutational status or MYC expression levels and anti-mitotic drug sensitivity when surveying a large database of anti-cancer drug responses. However, we report that the co-existence of KRAS mutations and high MYC expression predicts anti-mitotic drug sensitivity. Our findings reveal a novel function of oncogenic KRAS in regulating accurate mitotic progression and suggest new avenues to therapeutically target KRAS-mutant tumours and stratify patients in ongoing clinical trials of anti-mitotic drugs. PMID:27412232
STEM High School Communities: Common and Differing Features
ERIC Educational Resources Information Center
Tofel-Grehl, Colby; Callahan, Carolyn M.
Using observations and interviews, the researchers explore the experiences and perspectives of students, teachers, and administrators at six specialized high schools with a focus on science, technology, engineering, and mathematics (STEM) as they pertain to the practices and structures affecting student outcomes. Four themes were found to be…
Comparative analysis of mitosis-specific antibodies for bulk purification of mitotic populations by fluorescence-activated cell sorting.
Campbell, Amy E; Hsiung, Chris C-S; Blobel, Gerd A
Mitosis entails complex chromatin changes that have garnered increasing interest from biologists who study genome structure and regulation-fields that are being advanced by high-throughput sequencing (Seq) technologies. The application of these technologies to study the mitotic genome requires large numbers of highly pure mitotic cells, with minimal contamination from interphase cells, to ensure accurate measurement of phenomena specific to mitosis. Here, we optimized a fluorescence-activated cell sorting (FACS)-based method for isolating formaldehyde-fixed mitotic cells--at virtually 100% mitotic purity and in quantities sufficient for high-throughput genomic studies. We compared several commercially available antibodies that react with mitosis-specific epitopes over a range of concentrations and cell numbers, finding antibody MPM2 to be the most robust and cost-effective.
Mitotic Spindle Positioning in Breast Cancer
5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Tirnauer, Jennifer S. M.D. 5d. PROJECT NUMBER Email: email@example.com 5e. TASK...SUPPLEMENTARY NOTES 14. ABSTRACT The purpose of this project was to determine whether mitotic spindle position differs in benign versus malignant...postdoc working on the project has left, I want to re-visit the experiments with MCF-10A cells using serum free media. 15. SUBJECT TERMS breast
Automatic microscopy for mitotic cell location.
NASA Technical Reports Server (NTRS)
Herron, J.; Ranshaw, R.; Castle, J.; Wald, N.
Advances are reported in the development of an automatic microscope with which to locate hematologic or other cells in mitosis for subsequent chromosome analysis. The system under development is designed to perform the functions of: slide scanning to locate metaphase cells; conversion of images of selected cells into binary form; and on-line computer analysis of the digitized image for significant cytogenetic data. Cell detection criteria are evaluated using a test sample of 100 mitotic cells and 100 artifacts.
Qualitative Features of High Lift Hovering Dynamics and Inertial Manifolds
NASA Astrophysics Data System (ADS)
Gustafson, K.; Leben, R.; McArthur, J.; Mundt, M.
Hovering aerodynamics, such as that practiced by dragonflys, hummingbirds, and certain other small insects, utilizes special patterns of vorticity to generate high lift flows. Such lift as we measure it computationally on the airfoil surface is in good agreement with downstream thrust measured in the physical laboratory. In this paper we examine the qualitative signatures of this dynamical system. A connection to the theory of inertial manifolds, more specifically the instance of time-dependent slow manifolds, is initiated. Additional interest attaches to the fact that in our compact computational domain, the forcing is on the boundary. Because of its highly oscillatory nature, in this dynamics one proceeds rapidly up the bifurcation ladder at relatively low Reynolds numbers. Thus, aside from its intrinsic interest, the hover model provides an attractive vehicle for a better understanding of dynamical system attractor dynamics and inertial manifold theory.
A simplified Bcl-2 network model reveals quantitative determinants of cell-to-cell variation in sensitivity to anti-mitotic chemotherapeutics
NASA Astrophysics Data System (ADS)
Kueh, Hao Yuan; Zhu, Yanting; Shi, Jue
Anti-mitotic drugs constitute a major class of cytotoxic chemotherapeutics used in the clinic, killing cancer cells by inducing prolonged mitotic arrest that activates intrinsic apoptosis. Anti-mitotics-induced apoptosis is known to involve degradation of anti-apoptotic Bcl-2 proteins during mitotic arrest; however, it remains unclear how this mechanism accounts for significant heterogeneity observed in the cell death responses both within and between cancer cell types. To unravel quantitative determinants underlying variability in anti-mitotic drug response, we constructed a single-cell dynamical Bcl-2 network model describing cell death control during mitotic arrest, and constrained the model using experimental data from four representative cancer cell lines. The modeling analysis revealed that, given a variable, slowly accumulating pro-apoptotic signal arising from anti-apoptotic protein degradation, generation of a switch-like apoptotic response requires formation of pro-apoptotic Bak complexes with hundreds of subunits, suggesting a crucial role for high-order cooperativity. Moreover, we found that cell-type variation in susceptibility to drug-induced mitotic death arises primarily from differential expression of the anti-apoptotic proteins Bcl-xL and Mcl-1 relative to Bak. The dependence of anti-mitotic drug response on Bcl-xL and Mcl-1 that we derived from the modeling analysis provides a quantitative measure to predict sensitivity of distinct cancer cells to anti-mitotic drug treatment.
A simplified Bcl-2 network model reveals quantitative determinants of cell-to-cell variation in sensitivity to anti-mitotic chemotherapeutics
Kueh, Hao Yuan; Zhu, Yanting; Shi, Jue
Anti-mitotic drugs constitute a major class of cytotoxic chemotherapeutics used in the clinic, killing cancer cells by inducing prolonged mitotic arrest that activates intrinsic apoptosis. Anti-mitotics-induced apoptosis is known to involve degradation of anti-apoptotic Bcl-2 proteins during mitotic arrest; however, it remains unclear how this mechanism accounts for significant heterogeneity observed in the cell death responses both within and between cancer cell types. To unravel quantitative determinants underlying variability in anti-mitotic drug response, we constructed a single-cell dynamical Bcl-2 network model describing cell death control during mitotic arrest, and constrained the model using experimental data from four representative cancer cell lines. The modeling analysis revealed that, given a variable, slowly accumulating pro-apoptotic signal arising from anti-apoptotic protein degradation, generation of a switch-like apoptotic response requires formation of pro-apoptotic Bak complexes with hundreds of subunits, suggesting a crucial role for high-order cooperativity. Moreover, we found that cell-type variation in susceptibility to drug-induced mitotic death arises primarily from differential expression of the anti-apoptotic proteins Bcl-xL and Mcl-1 relative to Bak. The dependence of anti-mitotic drug response on Bcl-xL and Mcl-1 that we derived from the modeling analysis provides a quantitative measure to predict sensitivity of distinct cancer cells to anti-mitotic drug treatment. PMID:27811996
Mitotic spindle studied using picosecond laser scissors
NASA Astrophysics Data System (ADS)
Baker, N. M.; Botvinick, E. L.; Shi, Linda; Berns, M. B.; Wu, George
In previous studies we have shown that the second harmonic 532 nm, from a picosecond frequency doubled Nd:YAG laser, can cleanly and selectively disrupt spindle fiber microtubules in live cells (Botvinick et al 2004, Biophys. J. 87:4303-4212). In the present study we have ablated different locations and amounts of the metaphase mitotic spindle, and followed the cells in order to observe the fate of the irradiated spindle and the ability of the cell to continue through mitosis. Cells of the rat kangaroo line (PTK2) were stably transfected by ECFP-tubulin and, using fluorescent microscopy and the automated RoboLase microscope, (Botvinick and Berns, 2005, Micros. Res. Tech. 68:65-74) brightly fluorescent individual cells in metaphase were irradiated with 0.2447 nJ/micropulse corresponding to an irradiance of 1.4496*10^7 J/(ps*cm^2) . Upon irradiation the exposed part of the mitotic spindle immediately lost fluorescence and the following events were observed in the cells over time: (1) immediate contraction of the spindle pole towards the cut, (2) recovery of connection between pole and cut microtubule, (3) completion of mitosis. This system should be very useful in studying internal cellular dynamics of the mitotic spindle.
Ki-67 acts as a biological surfactant to disperse mitotic chromosomes.
Cuylen, Sara; Blaukopf, Claudia; Politi, Antonio Z; Müller-Reichert, Thomas; Neumann, Beate; Poser, Ina; Ellenberg, Jan; Hyman, Anthony A; Gerlich, Daniel W
Eukaryotic genomes are partitioned into chromosomes that form compact and spatially well-separated mechanical bodies during mitosis. This enables chromosomes to move independently of each other for segregation of precisely one copy of the genome to each of the nascent daughter cells. Despite insights into the spatial organization of mitotic chromosomes and the discovery of proteins at the chromosome surface, the molecular and biophysical bases of mitotic chromosome structural individuality have remained unclear. Here we report that the proliferation marker protein Ki-67 (encoded by the MKI67 gene), a component of the mitotic chromosome periphery, prevents chromosomes from collapsing into a single chromatin mass after nuclear envelope disassembly, thus enabling independent chromosome motility and efficient interactions with the mitotic spindle. The chromosome separation function of human Ki-67 is not confined within a specific protein domain, but correlates with size and net charge of truncation mutants that apparently lack secondary structure. This suggests that Ki-67 forms a steric and electrostatic charge barrier, similar to surface-active agents (surfactants) that disperse particles or phase-separated liquid droplets in solvents. Fluorescence correlation spectroscopy showed a high surface density of Ki-67 and dual-colour labelling of both protein termini revealed an extended molecular conformation, indicating brush-like arrangements that are characteristic of polymeric surfactants. Our study thus elucidates a biomechanical role of the mitotic chromosome periphery in mammalian cells and suggests that natural proteins can function as surfactants in intracellular compartmentalization.
Ki-67 acts as a biological surfactant to disperse mitotic chromosomes
Cuylen, Sara; Blaukopf, Claudia; Politi, Antonio Z.; Müller-Reichert, Thomas; Neumann, Beate; Poser, Ina; Ellenberg, Jan; Hyman, Anthony A.; Gerlich, Daniel W.
Summary Eukaryotic genomes are partitioned into chromosomes, which during mitosis form compact and spatially well-separated mechanical bodies1–3.This enables chromosomes to move independently of each other for segregation of precisely one copy of the genome to each of the nascent daughter cells. Despite insights into the spatial organization of mitotic chromosomes4 and the discovery of proteins at the chromosome surface3,5,6, the molecular and biophysical basis of mitotic chromosome individuality have remained unclear. We report that Ki-67, a component of the mitotic chromosome periphery, prevents chromosomes from collapsing into a single chromatin mass after nuclear envelope disassembly, thus enabling independent chromosome motility and efficient interactions with the mitotic spindle. The chromosome separation function of Ki-67 is not confined within a specific protein domain but correlates with size and net charge of truncation mutants that apparently lack secondary structure. This suggests that Ki-67 forms a steric and electrical barrier, similar to surface-active agents (surfactants) that disperse particles or phase-separated liquid droplets in solvents. Fluorescence correlation spectroscopy showed a high surface density of Ki-67 and dual-color labeling of both protein termini revealed an extended molecular conformation, indicating brush-like arrangements that are characteristic for polymeric surfactants. Our study thus elucidates a biomechanical role of the mitotic chromosome periphery and suggests that natural proteins can function as surfactants in intracellular compartmentalization. PMID:27362226
Dietary flavonoid fisetin induces a forced exit from mitosis by targeting the mitotic spindle checkpoint
Salmela, Anna-Leena; Pouwels, Jeroen; Varis, Asta; Kukkonen, Anu M.; Toivonen, Pauliina; Halonen, Pasi K.; Perälä, Merja; Kallioniemi, Olli; Gorbsky, Gary J.; Kallio, Marko J.
Fisetin is a natural flavonol present in edible vegetables, fruits and wine at 2–160 μg/g concentrations and an ingredient in nutritional supplements with much higher concentrations. The compound has been reported to exert anticarcinogenic effects as well as antioxidant and anti-inflammatory activity via its ability to act as an inhibitor of cell proliferation and free radical scavenger, respectively. Our cell-based high-throughput screen for small molecules that override chemically induced mitotic arrest identified fisetin as an antimitotic compound. Fisetin rapidly compromised microtubule drug-induced mitotic block in a proteasome-dependent manner in several human cell lines. Moreover, in unperturbed human cancer cells fisetin caused premature initiation of chromosome segregation and exit from mitosis without normal cytokinesis. To understand the molecular mechanism behind these mitotic errors, we analyzed the consequences of fisetin treatment on the localization and phoshorylation of several mitotic proteins. Aurora B, Bub1, BubR1 and Cenp-F rapidly lost their kinetochore/centromere localization and others became dephosphorylated upon addition of fisetin to the culture medium. Finally, we identified Aurora B kinase as a novel direct target of fisetin. The activity of Aurora B was significantly reduced by fisetin in vitro and in cells, an effect that can explain the observed forced mitotic exit, failure of cytokinesis and decreased cell viability. In conclusion, our data propose that fisetin perturbs spindle checkpoint signaling, which may contribute to the antiproliferative effects of the compound. PMID:19395653
Using in Vivo Biotinylated Ubiquitin to Describe a Mitotic Exit Ubiquitome from Human Cells *
Min, Mingwei; Mayor, Ugo; Dittmar, Gunnar; Lindon, Catherine
Mitotic division requires highly regulated morphological and biochemical changes to the cell. Upon commitment to exit mitosis, cells begin to remove mitotic regulators in a temporally and spatially controlled manner to bring about the changes that reestablish interphase. Ubiquitin-dependent pathways target these regulators to generate polyubiquitin-tagged substrates for degradation by the 26S proteasome. However, the lack of cell-based assays to investigate in vivo ubiquitination limits our knowledge of the identity of substrates of ubiquitin-mediated regulation in mitosis. Here we report an in vivo ubiquitin tagging system used in human cells that allows efficient purification of ubiquitin conjugates from synchronized cell populations. Coupling purification with mass spectrometry, we have identified a series of mitotic regulators targeted for polyubiquitination in mitotic exit. We show that some are new substrates of the anaphase-promoting complex/cyclosome and validate KIFC1 and RacGAP1/Cyk4 as two such targets involved respectively in timely mitotic spindle disassembly and cell spreading. We conclude that in vivo biotin tagging of ubiquitin can provide valuable information about the role of ubiquitin-mediated regulation in processes required for rebuilding interphase cells. PMID:24857844
Pair normalized channel feature and statistics-based learning for high-performance pedestrian detection
NASA Astrophysics Data System (ADS)
Zeng, Bobo; Wang, Guijin; Ruan, Zhiwei; Lin, Xinggang; Meng, Long
High-performance pedestrian detection with good accuracy and fast speed is an important yet challenging task in computer vision. We design a novel feature named pair normalized channel feature (PNCF), which simultaneously combines and normalizes two channel features in image channels, achieving a highly discriminative power and computational efficiency. PNCF applies to both gradient channels and color channels so that shape and appearance information are described and integrated in the same feature. To efficiently explore the formidably large PNCF feature space, we propose a statistics-based feature learning method to select a small number of potentially discriminative candidate features, which are fed into the boosting algorithm. In addition, channel compression and a hybrid pyramid are employed to speed up the multiscale detection. Experiments illustrate the effectiveness of PNCF and its learning method. Our proposed detector outperforms the state-of-the-art on several benchmark datasets in both detection accuracy and efficiency.
Highly featured amorphous silicon nanorod arrays for high-performance lithium-ion batteries
Soleimani-Amiri, Samaneh; Safiabadi Tali, Seied Ali; Azimi, Soheil; Sanaee, Zeinab; Mohajerzadeh, Shamsoddin
High aspect-ratio vertical structures of amorphous silicon have been realized using hydrogen-assisted low-density plasma reactive ion etching. Amorphous silicon layers with the thicknesses ranging from 0.5 to 10 μm were deposited using radio frequency plasma enhanced chemical vapor deposition technique. Standard photolithography and nanosphere colloidal lithography were employed to realize ultra-small features of the amorphous silicon. The performance of the patterned amorphous silicon structures as a lithium-ion battery electrode was investigated using galvanostatic charge-discharge tests. The patterned structures showed a superior Li-ion battery performance compared to planar amorphous silicon. Such structures are suitable for high current Li-ion battery applications such as electric vehicles.
Feature Selection Based on High Dimensional Model Representation for Hyperspectral Images.
Taskin Kaya, Gulsen; Kaya, Huseyin; Bruzzone, Lorenzo
In hyperspectral image analysis, the classification task has generally been addressed jointly with dimensionality reduction due to both the high correlation between the spectral features and the noise present in spectral bands which might significantly degrade classification performance. In supervised classification, limited training instances in proportion to the number of spectral features have negative impacts on the classification accuracy, which has known as Hughes effects or curse of dimensionality in the literature. In this paper, we focus on dimensionality reduction problem, and propose a novel feature-selection algorithm which is based on the method called High Dimensional Model Representation. The proposed algorithm is tested on some toy examples and hyperspectral datasets in comparison to conventional feature-selection algorithms in terms of classification accuracy, stability of the selected features and computational time. The results showed that the proposed approach provides both high classification accuracy and robust features with a satisfactory computational time.
Nitrogen deficiency inhibits leaf blade growth in Lolium perenne by increasing cell cycle duration and decreasing mitotic and post-mitotic growth rates.
Kavanová, Monika; Lattanzi, Fernando Alfredo; Schnyder, Hans
Nitrogen deficiency severely inhibits leaf growth. This response was analysed at the cellular level by growing Lolium perenne L. under 7.5 mM (high) or 1 mM (low) nitrate supply, and performing a kinematic analysis to assess the effect of nitrogen status on cell proliferation and cell growth in the leaf blade epidermis. Low nitrogen supply reduced leaf elongation rate (LER) by 43% through a similar decrease in the cell production rate and final cell length. The former was entirely because of a decreased average cell division rate (0.023 versus 0.032 h(-1)) and thus longer cell cycle duration (30 versus 22 h). Nitrogen status did not affect the number of division cycles of the initial cell's progeny (5.7), and accordingly the meristematic cell number (53). Meristematic cell length was unaffected by nitrogen deficiency, implying that the division and mitotic growth rates were equally impaired. The shorter mature cell length arose from a considerably reduced post-mitotic growth rate (0.033 versus 0.049 h(-1)). But, nitrogen stress did not affect the position where elongation stopped, and increased cell elongation duration. In conclusion, nitrogen deficiency limited leaf growth by increasing the cell cycle duration and decreasing mitotic and post-mitotic elongation rates, delaying cell maturation.
Non-iridescent transmissive structural color filter featuring highly efficient transmission and high excitation purity.
Shrestha, Vivek Raj; Lee, Sang-Shin; Kim, Eun-Soo; Choi, Duk-Yong
Nanostructure based color filtering has been considered an attractive replacement for current colorant pigmentation in the display technologies, in view of its increased efficiencies, ease of fabrication and eco-friendliness. For such structural filtering, iridescence relevant to its angular dependency, which poses a detrimental barrier to the practical development of high performance display and sensing devices, should be mitigated. We report on a non-iridescent transmissive structural color filter, fabricated in a large area of 76.2 × 25.4 mm(2), taking advantage of a stack of three etalon resonators in dielectric films based on a high-index cavity in amorphous silicon. The proposed filter features a high transmission above 80%, a high excitation purity of 0.93 and non-iridescence over a range of 160°, exhibiting no significant change in the center wavelength, dominant wavelength and excitation purity, which implies no change in hue and saturation of the output color. The proposed structure may find its potential applications to large-scale display and imaging sensor systems.
Differential Mitotic Stability of Yeast Disomes Derived from Triploid Meiosis
Campbell, Douglas; Doctor, John S.; Feuersanger, Jeane H.; Doolittle, Mark M.
The frequencies of recovered disomy among the meiotic segregants of yeast (Saccharomyces cerevisiae) triploids were assessed under conditions in which all 17 yeast chromosomes were monitored simultaneously. The studies employed inbred triploids, in which all homologous centromeres were identical by descent, and single haploid testers carrying genetic markers for all 17 linkage groups. The principal results include: (1) Ascospores from triploid meiosis germinate at frequencies comparable to those from normal diploids, but most fail to produce visible colonies due to the growth-retarding effects of high multiple disomy. (2) The probability of disome formation during triploid meiosis is the same for all chromosomes; disomy for any given chromosome does not exclude simultaneous disomy for any other chromosome. (3) The 17 yeast chromosomes fall into three frequency classes in terms of disome recovery. The results support the idea that multiply disomic meiotic segregants of the triploid experience repeated, nonrandom, post-germination mitotic chromosome losses (N+1→N) and that the observed variations in individual disome recovery are wholly attributable to inherent differences in disome mitotic stability. PMID:7035289
High sensitive and high resolution investigations of the Jovian S-burst emission modulation features
NASA Astrophysics Data System (ADS)
Litvinenko, G. V.; Konovalenko, A. A.; Rucker, H. O.; Lecacheux, A.; Vinogradov, V. V.
In spite of the long history of studying, the Jovian S-burst radiation still represents an event which needs to be investigated in detail. Many questions concerning this complex phenomenon are opened. One of the interesting problems is the different modulation features appearing on the dynamic spectra in dependence on the time resolution achieved in the experiment and also on the visualization time scale. It seems that in every concrete case the physical mechanism of the modulation is different. In connection to this the following statistical sets need to be fully collected and analyzed for each modulation effects: 1) observed conditions: dependence or independence on Jupiter - Io - observer position, season time, day-night time, the Solar activity; 2) observed parameters: sign and value of the frequency drift, lane's curvature, modulation depth, distances between the nearest lanes and their variety, scale of the modulation; 3) polarization properties. During the last years the new high sensitive recording facilities, such as the digital spectro-polarimiter (DSP) and waveform receiver (WFR) were created and installed into the largest decameter band antenna array UTR-2 (Kharkov, Ukraine). It can be noted that in the present time this combination (antenna + equipments) gives the best sensitiveness, band of analysis, dynamic range, time and frequency resolutions. The using of mentioned above technique allowed detecting new time-frequency features of the Jovian S-bursts. Several bright new results concerning the modulations were obtained. With the creation of new giant low frequency antenna array (LOFAR) and low wavelength array (LWA) the new possibilities of high level study of the Jovian DAM emission will appear. For instance, the combination of LOFAR and already existing instruments (max base in order of 2000 km) will permit to determine the spatial parameters and localization of an emission source. Future results may prove useful for the general understanding of
Amyloid Features and Neuronal Toxicity of Mature Prion Fibrils Are Highly Sensitive to High Pressure*
El Moustaine, Driss; Perrier, Veronique; Van Ba, Isabelle Acquatella-Tran; Meersman, Filip; Ostapchenko, Valeriy G.; Baskakov, Ilia V.; Lange, Reinhard; Torrent, Joan
Prion proteins (PrP) can aggregate into toxic and possibly infectious amyloid fibrils. This particular macrostructure confers on them an extreme and still unexplained stability. To provide mechanistic insights into this self-assembly process, we used high pressure as a thermodynamic tool for perturbing the structure of mature amyloid fibrils that were prepared from recombinant full-length mouse PrP. Application of high pressure led to irreversible loss of several specific amyloid features, such as thioflavin T and 8-anilino-1-naphthalene sulfonate binding, alteration of the characteristic proteinase K digestion pattern, and a significant decrease in the β-sheet structure and cytotoxicity of amyloid fibrils. Partial disaggregation of the mature fibrils into monomeric soluble PrP was observed. The remaining amyloid fibrils underwent a change in secondary structure that led to morphologically different fibrils composed of a reduced number of proto-filaments. The kinetics of these reactions was studied by recording the pressure-induced dissociation of thioflavin T from the amyloid fibrils. Analysis of the pressure and temperature dependence of the relaxation rates revealed partly unstructured and hydrated kinetic transition states and highlighted the importance of collapsing and hydrating inter- and intramolecular cavities to overcome the high free energy barrier that stabilizes amyloid fibrils. PMID:21357423
Implementation of High Dimensional Feature Map for Segmentation of MR Images
He, Renjie; Sajja, Balasrinivasa Rao; Narayana, Ponnada A.
A method that considerably reduces the computational and memory complexities associated with the generation of high dimensional (≥3) feature maps for image segmentation is described. The method is based on the K-nearest neighbor (KNN) classification and consists of two parts: preprocessing of feature space and fast KNN. This technique is implemented on a PC and applied for generating three-and four-dimensional feature maps for segmenting MR brain images of multiple sclerosis patients. PMID:16240091
Global Phosphoproteomic Mapping of Early Mitotic Exit in Human Cells Identifies Novel Substrate Dephosphorylation Motifs
McCloy, Rachael A.; Parker, Benjamin L.; Rogers, Samuel; Chaudhuri, Rima; Gayevskiy, Velimir; Hoffman, Nolan J.; Ali, Naveid; Watkins, D. Neil; Daly, Roger J.; James, David E.; Lorca, Thierry; Castro, Anna; Burgess, Andrew
Entry into mitosis is driven by the coordinated phosphorylation of thousands of proteins. For the cell to complete mitosis and divide into two identical daughter cells it must regulate dephosphorylation of these proteins in a highly ordered, temporal manner. There is currently a lack of a complete understanding of the phosphorylation changes that occur during the initial stages of mitotic exit in human cells. Therefore, we performed a large unbiased, global analysis to map the very first dephosphorylation events that occur as cells exit mitosis. We identified and quantified the modification of >16,000 phosphosites on >3300 unique proteins during early mitotic exit, providing up to eightfold greater resolution than previous studies. The data have been deposited to the ProteomeXchange with identifier PXD001559. Only a small fraction (∼10%) of phosphorylation sites were dephosphorylated during early mitotic exit and these occurred on proteins involved in critical early exit events, including organization of the mitotic spindle, the spindle assembly checkpoint, and reformation of the nuclear envelope. Surprisingly this enrichment was observed across all kinase consensus motifs, indicating that it is independent of the upstream phosphorylating kinase. Therefore, dephosphorylation of these sites is likely determined by the specificity of phosphatase/s rather than the activity of kinase/s. Dephosphorylation was significantly affected by the amino acids at and surrounding the phosphorylation site, with several unique evolutionarily conserved amino acids correlating strongly with phosphorylation status. These data provide a potential mechanism for the specificity of phosphatases, and how they co-ordinate the ordered events of mitotic exit. In summary, our results provide a global overview of the phosphorylation changes that occur during the very first stages of mitotic exit, providing novel mechanistic insight into how phosphatase/s specifically regulate this critical
Global Phosphoproteomic Mapping of Early Mitotic Exit in Human Cells Identifies Novel Substrate Dephosphorylation Motifs.
McCloy, Rachael A; Parker, Benjamin L; Rogers, Samuel; Chaudhuri, Rima; Gayevskiy, Velimir; Hoffman, Nolan J; Ali, Naveid; Watkins, D Neil; Daly, Roger J; James, David E; Lorca, Thierry; Castro, Anna; Burgess, Andrew
Entry into mitosis is driven by the coordinated phosphorylation of thousands of proteins. For the cell to complete mitosis and divide into two identical daughter cells it must regulate dephosphorylation of these proteins in a highly ordered, temporal manner. There is currently a lack of a complete understanding of the phosphorylation changes that occur during the initial stages of mitotic exit in human cells. Therefore, we performed a large unbiased, global analysis to map the very first dephosphorylation events that occur as cells exit mitosis. We identified and quantified the modification of >16,000 phosphosites on >3300 unique proteins during early mitotic exit, providing up to eightfold greater resolution than previous studies. The data have been deposited to the ProteomeXchange with identifier PXD001559. Only a small fraction (∼ 10%) of phosphorylation sites were dephosphorylated during early mitotic exit and these occurred on proteins involved in critical early exit events, including organization of the mitotic spindle, the spindle assembly checkpoint, and reformation of the nuclear envelope. Surprisingly this enrichment was observed across all kinase consensus motifs, indicating that it is independent of the upstream phosphorylating kinase. Therefore, dephosphorylation of these sites is likely determined by the specificity of phosphatase/s rather than the activity of kinase/s. Dephosphorylation was significantly affected by the amino acids at and surrounding the phosphorylation site, with several unique evolutionarily conserved amino acids correlating strongly with phosphorylation status. These data provide a potential mechanism for the specificity of phosphatases, and how they co-ordinate the ordered events of mitotic exit. In summary, our results provide a global overview of the phosphorylation changes that occur during the very first stages of mitotic exit, providing novel mechanistic insight into how phosphatase/s specifically regulate this critical
Miniaturization of mitotic index cell-based assay using "wall-less" plate technology.
Le Guezennec, Xavier; Phong, Mark; Nor, Liyana; Kim, Namyong
The use of microscopic imaging for the accurate assessment of cells in mitosis is hampered by the round morphology of mitotic cells, which renders them poorly adherent and highly susceptible to loss during the washing stage of cell-based assays. Here, to circumvent these limitations, we make use of DropArray, a recent technology that allows high retention of weakly adherent cells and suspension cells. DropArray offers the competitive advantage of maintaining the classic high throughput format of microtiter plates while reducing classic microwell volume by up to 90% by using a drop format. Here, we present a mitotic index cell-based assay using the mitosis marker phospho histone H3 at serine 10 on a DropArray 384-well plate format. Dose-response curve analysis of the mitotic index assay with an antimitotic drug (docetaxel) on DropArray is presented that shows an effective dosage compared to previous established results similar to those obtained with conventional microtiter plates. The mitotic index assay with DropArray showed a Z-factor >0.6. Our results validate DropArray as a suitable platform for high throughput screening for compounds affecting mitosis or the cell cycle.
Grading of well-differentiated pancreatic neuroendocrine tumors is improved by the inclusion of both Ki67 proliferative index and mitotic rate.
McCall, Chad M; Shi, Chanjuan; Cornish, Toby C; Klimstra, David S; Tang, Laura H; Basturk, Olca; Mun, Liew Jun; Ellison, Trevor A; Wolfgang, Christopher L; Choti, Michael A; Schulick, Richard D; Edil, Barish H; Hruban, Ralph H
The grading system for pancreatic neuroendocrine tumors (PanNETs) adopted in 2010 by the World Health Organization (WHO) mandates the use of both mitotic rate and Ki67/MIB-1 index in defining the proliferative rate and assigning the grade. In cases when these measures are not concordant for grade, it is recommended to assign the higher grade, but specific data justifying this approach do not exist. Thus, we counted mitotic figures and immunolabeled, using the Ki67 antibody, 297 WHO mitotic grade 1 and 2 PanNETs surgically resected at a single institution. We quantified the Ki67 proliferative index by marking at least 500 cells in "hot spots" and by using digital image analysis software to count each marked positive/negative cell and then compared the results with histologic features and overall survival. Of 264 WHO mitotic grade 1 PanNETs, 33% were WHO grade 2 by Ki67 proliferative index. Compared with concordant grade 1 tumors, grade-discordant tumors were more likely to have metastases to lymph node (56% vs. 34%) (P<0.01) and to distant sites (46% vs. 12%) (P<0.01). Discordant mitotic grade 1 PanNETs also showed statistically significantly more infiltrative growth patterns, perineural invasion, and small vessel invasion. Overall survival was significantly different (P<0.01), with discordant mitotic grade 1 tumors showing a median survival of 12 years compared with 16.7 years for concordant grade 1 tumors. Conversely, mitotic grade 1/Ki67 grade 2 PanNETs showed few significant differences from tumors that were mitotic grade 2 and either Ki67 grade 1 or 2. Our data demonstrate that mitotic rate and Ki67-based grades of PanNETs are often discordant, and when the Ki67 grade is greater than the mitotic grade, clinical outcomes and histopathologic features are significantly worse than concordant grade 1 tumors. Patients with discordant mitotic grade 1/Ki67 grade 2 tumors have shorter overall survival and larger tumors with more metastases and more aggressive histologic
Mitotic recombination of chromosome 17 in astrocytomas
James, C.D.; Carlbom, E.; Nordenskjold, M.; Collins, V.P.; Cavenee, W.K. )
Allelic combinations at seven loci on human chromosome 17 defined by restriction fragment length polymorphisms were determined in tumor and normal tissues from 35 patients with gliomas. Loss of constitutional heterozygosity at one or more of these loci was observed in 8 of the 24 tumors displaying astrocytic differentiation and in the single primitive neuroectodermal tumor examined. The astrocytomas showing these losses included examples of each adult malignancy grade of the disease, including glioblastoma (malignancy grade IV), and seven of them demonstrated concurrent maintenance of heterozygosity for at least one chromosome 17 locus. Determination of allele dosage together with the genotypic data indicated that the tumor chromosomes 17 were derived by mitotic recombination in 7 of the 9 cases with shared homozygosity of the region 17p11.2-ptr in all cases. In contrast, tumors of oligodendrocytic, ependymal, or mixed cellular differentiation did not exhibit loss of alleles at any of the loci examined. These data suggest that the somatic attainment of homozygosity for loci on chromosome 17p is frequently associated with the oncogenesis of central nervous system tumors, particularly those showing solely astrocytic differentiation, and that mitotic recombination mapping is a useful approach towards the subregional localization of a locus whose rearrangement is involved in this disease.
Divergence of mitotic strategies in fission yeasts
Gu, Ying; Yam, Candice; Oliferenko, Snezhana
The aim of mitosis is to produce two daughter nuclei, each containing a chromosome complement identical to that of the mother nucleus. This can be accomplished through a variety of strategies, with "open" and "closed" modes of mitosis positioned at the opposite ends of the spectrum and a range of intermediate patterns in between. In the "closed" mitosis, the nuclear envelope remains intact throughout the nuclear division. In the "open" division type, the envelope of the original nucleus breaks down early in mitosis and reassembles around the segregated daughter genomes. In any case, the nuclear membrane has to remodel to accommodate the mitotic spindle assembly, chromosome segregation and formation of the daughter nuclei. We have recently shown that within the fission yeast clade, the mitotic control of the nuclear surface area may determine the choice between the nuclear envelope breakdown and a fully "closed" division. Here we discuss our data and argue that comparative cell biology studies using two fission yeast species, Schizosaccharomyces pombe and Schizosaccharomyces japonicus, could provide unprecedented insights into physiology and evolution of mitosis. PMID:22572960
Optical high-performance computing: introduction to the JOSA A and Applied Optics feature.
Caulfield, H John; Dolev, Shlomi; Green, William M J
The feature issues in both Applied Optics and the Journal of the Optical Society of America A focus on topics of immediate relevance to the community working in the area of optical high-performance computing.
MELK is an oncogenic kinase essential for mitotic progression in basal-like breast cancer cells
Wang, Yubao; Lee, Young-Mi; Baitsch, Lukas; Huang, Alan; Xiang, Yi; Tong, Haoxuan; Lako, Ana; Von, Thanh; Choi, Christine; Lim, Elgene; Min, Junxia; Li, Li; Stegmeier, Frank; Schlegel, Robert; Eck, Michael J; Gray, Nathanael S; Mitchison, Timothy J; Zhao, Jean J
Despite marked advances in breast cancer therapy, basal-like breast cancer (BBC), an aggressive subtype of breast cancer usually lacking estrogen and progesterone receptors, remains difficult to treat. In this study, we report the identification of MELK as a novel oncogenic kinase from an in vivo tumorigenesis screen using a kinome-wide open reading frames (ORFs) library. Analysis of clinical data reveals a high level of MELK overexpression in BBC, a feature that is largely dependent on FoxM1, a master mitotic transcription factor that is also found to be highly overexpressed in BBC. Ablation of MELK selectively impairs proliferation of basal-like, but not luminal breast cancer cells both in vitro and in vivo. Mechanistically, depletion of MELK in BBC cells induces caspase-dependent cell death, preceded by defective mitosis. Finally, we find that Melk is not required for mouse development and physiology. Together, these data indicate that MELK is a normally non-essential kinase, but is critical for BBC and thus represents a promising selective therapeutic target for the most aggressive subtype of breast cancer. DOI: http://dx.doi.org/10.7554/eLife.01763.001 PMID:24844244
Using high spectral resolution spectrophotometry to study broad mineral absorption features on Mars
NASA Technical Reports Server (NTRS)
Blaney, D. L.; Crisp, D.
Traditionally telescopic measurements of mineralogic absorption features have been made using relatively low to moderate (R=30-300) spectral resolution. Mineralogic absorption features tend to be broad so high resolution spectroscopy (R greater than 10,000) does not provide significant additional compositional information. Low to moderate resolution spectroscopy allows an observer to obtain data over a wide wavelength range (hundreds to thousands of wavenumbers) compared to the several wavenumber intervals that are collected using high resolution spectrometers. However, spectrophotometry at high resolution has major advantages over lower resolution spectroscopy in situations that are applicable to studies of the Martian surface, i.e., at wavelengths where relatively weak surface absorption features and atmospheric gas absorption features both occur.
FTO influences adipogenesis by regulating mitotic clonal expansion.
Merkestein, Myrte; Laber, Samantha; McMurray, Fiona; Andrew, Daniel; Sachse, Gregor; Sanderson, Jeremy; Li, Mengdi; Usher, Samuel; Sellayah, Dyan; Ashcroft, Frances M; Cox, Roger D
The fat mass and obesity-associated (FTO) gene plays a pivotal role in regulating body weight and fat mass; however, the underlying mechanisms are poorly understood. Here we show that primary adipocytes and mouse embryonic fibroblasts (MEFs) derived from FTO overexpression (FTO-4) mice exhibit increased potential for adipogenic differentiation, while MEFs derived from FTO knockout (FTO-KO) mice show reduced adipogenesis. As predicted from these findings, fat pads from FTO-4 mice fed a high-fat diet show more numerous adipocytes. FTO influences adipogenesis by regulating events early in adipogenesis, during the process of mitotic clonal expansion. The effect of FTO on adipogenesis appears to be mediated via enhanced expression of the pro-adipogenic short isoform of RUNX1T1, which enhanced adipocyte proliferation, and is increased in FTO-4 MEFs and reduced in FTO-KO MEFs. Our findings provide novel mechanistic insight into how upregulation of FTO leads to obesity.
High quality machine-robust image features: Identification in nonsmall cell lung cancer computed tomography images
Hunter, Luke A.; Krafft, Shane; Stingo, Francesco; Choi, Haesun; Martel, Mary K.; Kry, Stephen F.; Court, Laurence E.
Purpose: For nonsmall cell lung cancer (NSCLC) patients, quantitative image features extracted from computed tomography (CT) images can be used to improve tumor diagnosis, staging, and response assessment. For these findings to be clinically applied, image features need to have high intra and intermachine reproducibility. The objective of this study is to identify CT image features that are reproducible, nonredundant, and informative across multiple machines. Methods: Noncontrast-enhanced, test-retest CT image pairs were obtained from 56 NSCLC patients imaged on three CT machines from two institutions. Two machines ("M1" and "M2") used cine 4D-CT and one machine ("M3") used breath-hold helical 3D-CT. Gross tumor volumes (GTVs) were semiautonomously segmented then pruned by removing voxels with CT numbers less than a prescribed Hounsfield unit (HU) cutoff. Three hundred and twenty eight quantitative image features were extracted from each pruned GTV based on its geometry, intensity histogram, absolute gradient image, co-occurrence matrix, and run-length matrix. For each machine, features with concordance correlation coefficient values greater than 0.90 were considered reproducible. The Dice similarity coefficient (DSC) and the Jaccard index (JI) were used to quantify reproducible feature set agreement between machines. Multimachine reproducible feature sets were created by taking the intersection of individual machine reproducible feature sets. Redundant features were removed through hierarchical clustering based on the average correlation between features across multiple machines. Results: For all image types, GTV pruning was found to negatively affect reproducibility (reported results use no HU cutoff). The reproducible feature percentage was highest for average images (M1 = 90.5%, M2 = 94.5%, M1∩M2 = 86.3%), intermediate for end-exhale images (M1 = 75.0%, M2 = 71.0%, M1∩M2 = 52.1%), and lowest for breath-hold images (M3 = 61.0%). Between M1 and M2
Phosphohistone H3 expression correlates with manual mitotic counts and aids in identification of "hot spots" in fibroepithelial tumors of the breast.
Ginter, Paula S; Shin, Sandra J; Liu, Yifang; Chen, Zhengming; D'Alfonso, Timothy M
Classification of mammary fibroepithelial tumors (FETs) relies on assessment of mitotic activity, among other histopathologic parameters. Routine hematoxylin and eosin (H&E) mitotic counts can be subjective and time consuming. Difficulty may arise in identifying "true" mitoses for a variety of reasons. Phosphorylation of histone H3 protein (PHH3) is correlated with mitotic chromatin condensation. The utility of PHH3 immunohistochemical staining to identify mitoses has been demonstrated in multiple organ systems. In this study, we examined the utility of PHH3 in assessing mitotic activity in FETs and compared PHH3- with H&E-determined mitotic counts. PHH3-stained mitoses were readily identifiable at ×10 magnification and allowed for rapid identification of mitotic "hot spots." Median mitotic counts/10 high-power fields for fibroadenoma, benign phyllodes tumor, borderline phyllodes tumor (BlnPT), and malignant phyllodes tumor (MPT) were 0, 0.5, 4.25, and 9, respectively on H&E, and 0, 0.75, 4.5, and 8, respectively for PHH3. Among all FETs, there was a strong positive correlation between H&E- and PHH3-determined mitotic counts (r=0.91, P<.001). Using PHH3, 2 cases would be reclassified, both from BlnPT to MPT. PHH3-determined counts correlated with H&E-determined counts in FETs. Using PHH3, a small number of cases were reclassified from BlnPT to MPT, for which treatment is similar. Although H&E-determined counts remain the criterion standard for assessing mitotic activity in FETs, PHH3 may be a useful adjunctive tool in some cases and is helpful in identifying mitotic hot spots.
Local-learning-based feature selection for high-dimensional data analysis.
Sun, Yijun; Todorovic, Sinisa; Goodison, Steve
This paper considers feature selection for data classification in the presence of a huge number of irrelevant features. We propose a new feature-selection algorithm that addresses several major issues with prior work, including problems with algorithm implementation, computational complexity, and solution accuracy. The key idea is to decompose an arbitrarily complex nonlinear problem into a set of locally linear ones through local learning, and then learn feature relevance globally within the large margin framework. The proposed algorithm is based on well-established machine learning and numerical analysis techniques, without making any assumptions about the underlying data distribution. It is capable of processing many thousands of features within minutes on a personal computer while maintaining a very high accuracy that is nearly insensitive to a growing number of irrelevant features. Theoretical analyses of the algorithm's sample complexity suggest that the algorithm has a logarithmical sample complexity with respect to the number of features. Experiments on 11 synthetic and real-world data sets demonstrate the viability of our formulation of the feature-selection problem for supervised learning and the effectiveness of our algorithm.
Local-Learning-Based Feature Selection for High-Dimensional Data Analysis
Sun, Yijun; Todorovic, Sinisa; Goodison, Steve
This paper considers feature selection for data classification in the presence of a huge number of irrelevant features. We propose a new feature-selection algorithm that addresses several major issues with prior work, including problems with algorithm implementation, computational complexity, and solution accuracy. The key idea is to decompose an arbitrarily complex nonlinear problem into a set of locally linear ones through local learning, and then learn feature relevance globally within the large margin framework. The proposed algorithm is based on well-established machine learning and numerical analysis techniques, without making any assumptions about the underlying data distribution. It is capable of processing many thousands of features within minutes on a personal computer while maintaining a very high accuracy that is nearly insensitive to a growing number of irrelevant features. Theoretical analyses of the algorithm's sample complexity suggest that the algorithm has a logarithmical sample complexity with respect to the number of features. Experiments on 11 synthetic and real-world data sets demonstrate the viability of our formulation of the feature-selection problem for supervised learning and the effectiveness of our algorithm. PMID:20634556
On Efficient Feature Ranking Methods for High-Throughput Data Analysis.
Liao, Bo; Jiang, Yan; Liang, Wei; Peng, Lihong; Peng, Li; Hanyurwimfura, Damien; Li, Zejun; Chen, Min
Efficient mining of high-throughput data has become one of the popular themes in the big data era. Existing biology-related feature ranking methods mainly focus on statistical and annotation information. In this study, two efficient feature ranking methods are presented. Multi-target regression and graph embedding are incorporated in an optimization framework, and feature ranking is achieved by introducing structured sparsity norm. Unlike existing methods, the presented methods have two advantages: (1) the feature subset simultaneously account for global margin information as well as locality manifold information. Consequently, both global and locality information are considered. (2) Features are selected by batch rather than individually in the algorithm framework. Thus, the interactions between features are considered and the optimal feature subset can be guaranteed. In addition, this study presents a theoretical justification. Empirical experiments demonstrate the effectiveness and efficiency of the two algorithms in comparison with some state-of-the-art feature ranking methods through a set of real-world gene expression data sets.
Direct preparation protocol to obtain mitotic chromosomes from canine mammary tumors.
Morais, C S D; Affonso, P R A M; Bitencourt, J A; Wenceslau, A A
Currently, mammary neoplasms in female canines are a serious problem in veterinary clinics. In addition, the canine species is an excellent disease model for human oncology because of the biological and genetic similarities between the species. Cytogenetics has allowed further study of the characterization of neoplasms in canines. We hypothesized that the use of a direct preparation protocol for mitotic chromosome analysis would provide a simple and low cost protocol for use in all laboratories. The objective of this method is to display in a few hours of dividing cells just like the time of collection since cell division in tissue can be obtained. Ten female canines with the spontaneous occurrence of mammary neoplasia were used to test a pioneering direct preparation protocol to obtain mitotic chromosomes. The excised breast tumor tissue fragments were subjected to the protocol consisting of treatment with colchicine, treatment with hypotonic solution, and fixation. Mitotic chromosomes were absent in cell suspensions of only two samples among the 10 materials analyzed, based on the analysis of five blades for each preparation obtained. So, the cell suspension obtained allowed for the observation of eight tissue samples viable for cytogenetic analysis, five of which had excellent numbers of mitotic chromosomes. However, the technique was unsuccessful in producing high-quality cell suspensions because of inadequate condensation and scattering of chromosomes. While adjustments to methodological procedures are needed, this protocol represents a low cost and simplified method to study the cytogenetics of canine tumors.
The flavonoid eupatorin inactivates the mitotic checkpoint leading to polyploidy and apoptosis
Salmela, Anna-Leena; Pouwels, Jeroen; Kukkonen-Macchi, Anu; Waris, Sinikka; Toivonen, Pauliina; Jaakkola, Kimmo; Maeki-Jouppila, Jenni; Kallio, Lila; Kallio, Marko J.
The spindle assembly checkpoint (SAC) is a conserved mechanism that ensures the fidelity of chromosome distribution in mitosis by preventing anaphase onset until the correct bipolar microtubule-kinetochore attachments are formed. Errors in SAC function may contribute to tumorigenesis by inducing numerical chromosome anomalies (aneuploidy). On the other hand, total disruption of SAC can lead to massive genomic imbalance followed by cell death, a phenomena that has therapeutic potency. We performed a cell-based high-throughput screen with a compound library of 2000 bioactives for novel SAC inhibitors and discovered a plant-derived phenolic compound eupatorin (3 Prime ,5-dihydroxy-4 Prime ,6,7-trimethoxyflavone) as an anti-mitotic flavonoid. The premature override of the microtubule drug-imposed mitotic arrest by eupatorin is dependent on microtubule-kinetochore attachments but not interkinetochore tension. Aurora B kinase activity, which is essential for maintenance of normal SAC signaling, is diminished by eupatorin in cells and in vitro providing a mechanistic explanation for the observed forced mitotic exit. Eupatorin likely has additional targets since eupatorin treatment of pre-mitotic cells causes spindle anomalies triggering a transient M phase delay followed by impaired cytokinesis and polyploidy. Finally, eupatorin potently induces apoptosis in multiple cancer cell lines and suppresses cancer cell proliferation in organotypic 3D cell culture model.
Change detection in high resolution SAR images based on multiscale texture features
NASA Astrophysics Data System (ADS)
Wen, Caihuan; Gao, Ziqiang
This paper studied on change detection algorithm of high resolution (HR) Synthetic Aperture Radar (SAR) images based on multi-scale texture features. Firstly, preprocessed multi-temporal Terra-SAR images were decomposed by 2-D dual tree complex wavelet transform (DT-CWT), and multi-scale texture features were extracted from those images. Then, log-ratio operation was utilized to get difference images, and the Bayes minimum error theory was used to extract change information from difference images. Lastly, precision assessment was done. Meanwhile, we compared with the result of method based on texture features extracted from gray-level cooccurrence matrix (GLCM). We had a conclusion that, change detection algorithm based on multi-scale texture features has a great more improvement, which proves an effective method to change detect of high spatial resolution SAR images.
An improved retinal vessel segmentation method based on high level features for pathological images.
Ganjee, Razieh; Azmi, Reza; Gholizadeh, Behrouz
Most of the retinal blood vessel segmentation approaches use low level features, resulting in segmenting non-vessel structures together with vessel structures in pathological retinal images. In this paper, a new segmentation method based on high level features is proposed which can process the structure of vessel and non-vessel independently. In this method, segmentation is done in two steps. First, using low level features segmentation is accomplished. Second, using high level features, the non-vessel components are removed. For evaluation, STARE database is used which is publicly available in this field. The results show that the proposed method has 0.9536 accuracy and 0.0191 false positive average on all images of the database and 0.9542 accuracy and 0.0236 false positive average on pathological images. Therefore, the proposed approach shows acceptable accuracy on all images compared to other state of the art methods, and the least false positive average on pathological images.
Identification of a novel mitotic phosphorylation motif associated with protein localization to the mitotic apparatus
Yang, Feng; Camp, David G.; Gritsenko, Marina A.; Luo, Quanzhou; Kelly, Ryan T.; Clauss, Therese RW; Brinkley, William R.; Smith, Richard D.; Stenoien, David L.
The chromosomal passenger complex (CPC) is a critical regulator of chromosome, cytoskeleton and membrane dynamics during mitosis. Here, we identified phosphopeptides and phosphoprotein complexes recognized by a phosphorylation specific antibody that labels the CPC using liquid chromatography coupled to mass spectrometry. A mitotic phosphorylation motif (PX{G/T/S}{L/M}[pS]P or WGL[pS]P) was identified in 11 proteins including Fzr/Cdh1 and RIC-8, two proteins with potential links to the CPC. Phosphoprotein complexes contained known CPC components INCENP, Aurora-B and TD-60, as well as SMAD2, 14-3-3 proteins, PP2A, and Cdk1, a likely kinase for this motif. Protein sequence analysis identified phosphorylation motifs in additional proteins including SMAD2, Plk3 and INCENP. Mitotic SMAD2 and Plk3 phosphorylation was confirmed using phosphorylation specific antibodies, and in the case of Plk3, phosphorylation correlates with its localization to the mitotic apparatus. A mutagenesis approach was used to show INCENP phosphorylation is required for midbody localization. These results provide evidence for a shared phosphorylation event that regulates localization of critical proteins during mitosis.
Genetic variation in mitotic regulatory pathway genes is associated with breast tumor grade
Purrington, Kristen S.; Slettedahl, Seth; Bolla, Manjeet K.; Michailidou, Kyriaki; Czene, Kamila; Nevanlinna, Heli; Bojesen, Stig E.; Andrulis, Irene L.; Cox, Angela; Hall, Per; Carpenter, Jane; Yannoukakos, Drakoulis; Haiman, Christopher A.; Fasching, Peter A.; Mannermaa, Arto; Winqvist, Robert; Brenner, Hermann; Lindblom, Annika; Chenevix-Trench, Georgia; Benitez, Javier; Swerdlow, Anthony; Kristensen, Vessela; Guénel, Pascal; Meindl, Alfons; Darabi, Hatef; Eriksson, Mikael; Fagerholm, Rainer; Aittomäki, Kristiina; Blomqvist, Carl; Nordestgaard, Børge G.; Nielsen, Sune F.; Flyger, Henrik; Wang, Xianshu; Olswold, Curtis; Olson, Janet E.; Mulligan, Anna Marie; Knight, Julia A.; Tchatchou, Sandrine; Reed, Malcolm W.R.; Cross, Simon S.; Liu, Jianjun; Li, Jingmei; Humphreys, Keith; Clarke, Christine; Scott, Rodney; Fostira, Florentia; Fountzilas, George; Konstantopoulou, Irene; Henderson, Brian E.; Schumacher, Fredrick; Le Marchand, Loic; Ekici, Arif B.; Hartmann, Arndt; Beckmann, Matthias W.; Hartikainen, Jaana M.; Kosma, Veli-Matti; Kataja, Vesa; Jukkola-Vuorinen, Arja; Pylkäs, Katri; Kauppila, Saila; Dieffenbach, Aida Karina; Stegmaier, Christa; Arndt, Volker; Margolin, Sara; Balleine, Rosemary; Arias Perez, Jose Ignacio; Pilar Zamora, M.; Menéndez, Primitiva; Ashworth, Alan; Jones, Michael; Orr, Nick; Arveux, Patrick; Kerbrat, Pierre; Truong, Thérèse; Bugert, Peter; Toland, Amanda E.; Ambrosone, Christine B.; Labrèche, France; Goldberg, Mark S.; Dumont, Martine; Ziogas, Argyrios; Lee, Eunjung; Dite, Gillian S.; Apicella, Carmel; Southey, Melissa C.; Long, Jirong; Shrubsole, Martha; Deming-Halverson, Sandra; Ficarazzi, Filomena; Barile, Monica; Peterlongo, Paolo; Durda, Katarzyna; Jaworska-Bieniek, Katarzyna; Tollenaar, Robert A.E.M.; Seynaeve, Caroline; Brüning, Thomas; Ko, Yon-Dschun; Van Deurzen, Carolien H.M.; Martens, John W.M.; Kriege, Mieke; Figueroa, Jonine D.; Chanock, Stephen J.; Lissowska, Jolanta; Tomlinson, Ian; Kerin, Michael J.; Miller, Nicola; Schneeweiss, Andreas; Tapper, William J.; Gerty, Susan M.; Durcan, Lorraine; Mclean, Catriona; Milne, Roger L.; Baglietto, Laura; dos Santos Silva, Isabel; Fletcher, Olivia; Johnson, Nichola; Van'T Veer, Laura J.; Cornelissen, Sten; Försti, Asta; Torres, Diana; Rüdiger, Thomas; Rudolph, Anja; Flesch-Janys, Dieter; Nickels, Stefan; Weltens, Caroline; Floris, Giuseppe; Moisse, Matthieu; Dennis, Joe; Wang, Qin; Dunning, Alison M.; Shah, Mitul; Brown, Judith; Simard, Jacques; Anton-Culver, Hoda; Neuhausen, Susan L.; Hopper, John L.; Bogdanova, Natalia; Dörk, Thilo; Zheng, Wei; Radice, Paolo; Jakubowska, Anna; Lubinski, Jan; Devillee, Peter; Brauch, Hiltrud; Hooning, Maartje; García-Closas, Montserrat; Sawyer, Elinor; Burwinkel, Barbara; Marmee, Frederick; Eccles, Diana M.; Giles, Graham G.; Peto, Julian; Schmidt, Marjanka; Broeks, Annegien; Hamann, Ute; Chang-Claude, Jenny; Lambrechts, Diether; Pharoah, Paul D.P.; Easton, Douglas; Pankratz, V. Shane; Slager, Susan; Vachon, Celine M.; Couch, Fergus J.
Mitotic index is an important component of histologic grade and has an etiologic role in breast tumorigenesis. Several small candidate gene studies have reported associations between variation in mitotic genes and breast cancer risk. We measured associations between 2156 single nucleotide polymorphisms (SNPs) from 194 mitotic genes and breast cancer risk, overall and by histologic grade, in the Breast Cancer Association Consortium (BCAC) iCOGS study (n = 39 067 cases; n = 42 106 controls). SNPs in TACC2 [rs17550038: odds ratio (OR) = 1.24, 95% confidence interval (CI) 1.16–1.33, P = 4.2 × 10−10) and EIF3H (rs799890: OR = 1.07, 95% CI 1.04–1.11, P = 8.7 × 10−6) were significantly associated with risk of low-grade breast cancer. The TACC2 signal was retained (rs17550038: OR = 1.15, 95% CI 1.07–1.23, P = 7.9 × 10−5) after adjustment for breast cancer risk SNPs in the nearby FGFR2 gene, suggesting that TACC2 is a novel, independent genome-wide significant genetic risk locus for low-grade breast cancer. While no SNPs were individually associated with high-grade disease, a pathway-level gene set analysis showed that variation across the 194 mitotic genes was associated with high-grade breast cancer risk (P = 2.1 × 10−3). These observations will provide insight into the contribution of mitotic defects to histological grade and the etiology of breast cancer. PMID:24927736
Genetic variation in mitotic regulatory pathway genes is associated with breast tumor grade.
Purrington, Kristen S; Slettedahl, Seth; Bolla, Manjeet K; Michailidou, Kyriaki; Czene, Kamila; Nevanlinna, Heli; Bojesen, Stig E; Andrulis, Irene L; Cox, Angela; Hall, Per; Carpenter, Jane; Yannoukakos, Drakoulis; Haiman, Christopher A; Fasching, Peter A; Mannermaa, Arto; Winqvist, Robert; Brenner, Hermann; Lindblom, Annika; Chenevix-Trench, Georgia; Benitez, Javier; Swerdlow, Anthony; Kristensen, Vessela; Guénel, Pascal; Meindl, Alfons; Darabi, Hatef; Eriksson, Mikael; Fagerholm, Rainer; Aittomäki, Kristiina; Blomqvist, Carl; Nordestgaard, Børge G; Nielsen, Sune F; Flyger, Henrik; Wang, Xianshu; Olswold, Curtis; Olson, Janet E; Mulligan, Anna Marie; Knight, Julia A; Tchatchou, Sandrine; Reed, Malcolm W R; Cross, Simon S; Liu, Jianjun; Li, Jingmei; Humphreys, Keith; Clarke, Christine; Scott, Rodney; Fostira, Florentia; Fountzilas, George; Konstantopoulou, Irene; Henderson, Brian E; Schumacher, Fredrick; Le Marchand, Loic; Ekici, Arif B; Hartmann, Arndt; Beckmann, Matthias W; Hartikainen, Jaana M; Kosma, Veli-Matti; Kataja, Vesa; Jukkola-Vuorinen, Arja; Pylkäs, Katri; Kauppila, Saila; Dieffenbach, Aida Karina; Stegmaier, Christa; Arndt, Volker; Margolin, Sara; Balleine, Rosemary; Arias Perez, Jose Ignacio; Pilar Zamora, M; Menéndez, Primitiva; Ashworth, Alan; Jones, Michael; Orr, Nick; Arveux, Patrick; Kerbrat, Pierre; Truong, Thérèse; Bugert, Peter; Toland, Amanda E; Ambrosone, Christine B; Labrèche, France; Goldberg, Mark S; Dumont, Martine; Ziogas, Argyrios; Lee, Eunjung; Dite, Gillian S; Apicella, Carmel; Southey, Melissa C; Long, Jirong; Shrubsole, Martha; Deming-Halverson, Sandra; Ficarazzi, Filomena; Barile, Monica; Peterlongo, Paolo; Durda, Katarzyna; Jaworska-Bieniek, Katarzyna; Tollenaar, Robert A E M; Seynaeve, Caroline; Brüning, Thomas; Ko, Yon-Dschun; Van Deurzen, Carolien H M; Martens, John W M; Kriege, Mieke; Figueroa, Jonine D; Chanock, Stephen J; Lissowska, Jolanta; Tomlinson, Ian; Kerin, Michael J; Miller, Nicola; Schneeweiss, Andreas; Tapper, William J; Gerty, Susan M; Durcan, Lorraine; Mclean, Catriona; Milne, Roger L; Baglietto, Laura; dos Santos Silva, Isabel; Fletcher, Olivia; Johnson, Nichola; Van'T Veer, Laura J; Cornelissen, Sten; Försti, Asta; Torres, Diana; Rüdiger, Thomas; Rudolph, Anja; Flesch-Janys, Dieter; Nickels, Stefan; Weltens, Caroline; Floris, Giuseppe; Moisse, Matthieu; Dennis, Joe; Wang, Qin; Dunning, Alison M; Shah, Mitul; Brown, Judith; Simard, Jacques; Anton-Culver, Hoda; Neuhausen, Susan L; Hopper, John L; Bogdanova, Natalia; Dörk, Thilo; Zheng, Wei; Radice, Paolo; Jakubowska, Anna; Lubinski, Jan; Devillee, Peter; Brauch, Hiltrud; Hooning, Maartje; García-Closas, Montserrat; Sawyer, Elinor; Burwinkel, Barbara; Marmee, Frederick; Eccles, Diana M; Giles, Graham G; Peto, Julian; Schmidt, Marjanka; Broeks, Annegien; Hamann, Ute; Chang-Claude, Jenny; Lambrechts, Diether; Pharoah, Paul D P; Easton, Douglas; Pankratz, V Shane; Slager, Susan; Vachon, Celine M; Couch, Fergus J
Mitotic index is an important component of histologic grade and has an etiologic role in breast tumorigenesis. Several small candidate gene studies have reported associations between variation in mitotic genes and breast cancer risk. We measured associations between 2156 single nucleotide polymorphisms (SNPs) from 194 mitotic genes and breast cancer risk, overall and by histologic grade, in the Breast Cancer Association Consortium (BCAC) iCOGS study (n = 39 067 cases; n = 42 106 controls). SNPs in TACC2 [rs17550038: odds ratio (OR) = 1.24, 95% confidence interval (CI) 1.16-1.33, P = 4.2 × 10(-10)) and EIF3H (rs799890: OR = 1.07, 95% CI 1.04-1.11, P = 8.7 × 10(-6)) were significantly associated with risk of low-grade breast cancer. The TACC2 signal was retained (rs17550038: OR = 1.15, 95% CI 1.07-1.23, P = 7.9 × 10(-5)) after adjustment for breast cancer risk SNPs in the nearby FGFR2 gene, suggesting that TACC2 is a novel, independent genome-wide significant genetic risk locus for low-grade breast cancer. While no SNPs were individually associated with high-grade disease, a pathway-level gene set analysis showed that variation across the 194 mitotic genes was associated with high-grade breast cancer risk (P = 2.1 × 10(-3)). These observations will provide insight into the contribution of mitotic defects to histological grade and the etiology of breast cancer.
NeuN expression correlates with reduced mitotic index of neoplastic cells in central neurocytomas.
Englund, C; Alvord, E C; Folkerth, R D; Silbergeld, D; Born, D E; Small, R; Hevner, R F
In the developing brain, neuronal differentiation is associated with permanent exit from the mitotic cycle. This raises the possibility that neuronal differentiation may suppress proliferative activity, even in neoplastic cells. As a first step towards understanding the relation between neuronal differentiation and mitotic cycling in brain tumours, we studied the expression of NeuN (a neuronal marker) and Ki-67 (a mitotic marker) by double-labelling immuno-fluorescence in 16 brain tumours with neuronal differentiation. The tumours included a series of 11 central neurocytomas, and five single cases of other tumour types. In the central neurocytomas, NeuN(+) cells had a 15-fold lower Ki-67 labelling index, on average, than did NeuN(-) cells (P < 0.01). In the other tumours (one extraventricular neurocytoma, one desmoplastic medulloblastoma, one olfactory neuroblastoma, one ganglioglioma and one anaplastic ganglioglioma), the Ki-67 labelling index was always at least fourfold lower in NeuN(+) cells than in NeuN(-) cells. These results indicate that neuronal differentiation is associated with a substantial decrease of proliferative activity in neoplastic cells of central neurocytomas, and suggest that the same may be true across diverse types of brain tumours. However, tumours with extensive neuronal differentiation may nevertheless have a high overall Ki-67 labelling index, if the mitotic activity of NeuN(-) cells is high. The correlation between NeuN expression and reduced mitotic activity in neurocytoma cells is consistent with the hypothesis that neuronal differentiation suppresses proliferation, but further studies will be necessary to determine causality and investigate underlying mechanisms.
Pores and ridges: high-resolution fingerprint matching using level 3 features.
Jain, Anil K; Chen, Yi; Demirkus, Meltem
Fingerprint friction ridge details are generally described in a hierarchical order at three different levels, namely, Level 1 (pattern), Level 2 (minutia points), and Level 3 (pores and ridge contours). Although latent print examiners frequently take advantage of Level 3 features to assist in identification, Automated Fingerprint Identification Systems (AFIS) currently rely only on Level 1 and Level 2 features. In fact, the Federal Bureau of Investigation's (FBI) standard of fingerprint resolution for AFIS is 500 pixels per inch (ppi), which is inadequate for capturing Level 3 features, such as pores. With the advances in fingerprint sensing technology, many sensors are now equipped with dual resolution (500 ppi/1,000 ppi) scanning capability. However, increasing the scan resolution alone does not necessarily provide any performance improvement in fingerprint matching, unless an extended feature set is utilized. As a result, a systematic study to determine how much performance gain one can achieve by introducing Level 3 features in AFIS is highly desired. We propose a hierarchical matching system that utilizes features at all the three levels extracted from 1,000 ppi fingerprint scans. Level 3 features, including pores and ridge contours, are automatically extracted using Gabor filters and wavelet transform and are locally matched using the Iterative Closest Point (ICP) algorithm. Our experiments show that Level 3 features carry significant discriminatory information. There is a relative reduction of 20 percent in the equal error rate (EER) of the matching system when Level 3 features are employed in combination with Level 1 and 2 features. This significant performance gain is consistently observed across various quality fingerprint images.
Classification of High Resolution C-Band PolSAR Data on Polarimetric and Texture Features
NASA Astrophysics Data System (ADS)
Zhao, Lei; Chen, Erxue; Li, Zengyuan; Feng, Qi; Li, Lan
PolSAR image classification is an important technique in the remote sensing area. For high resolution PolSAR image, polarimetric and texture features are equally important for the high resolution PolSAR image classification. The texture features are mainly extracted through Gray Level Co-occurrence Matrix (GLCM) method, but this method has some deficiencies. First, GLCM method can only work on gray-scale images; Secondly, the number of texture features extracted by GLCM method is generally up dozens, or even hundreds. Too many features may exist larger redundancy and will increase the complexity of classification. Therefore, this paper introduces a new texture feature factor-RK that derived from PolSAR image non-Gaussian statistic model.Using the domestic airborne C-band PolSAR image data, we completed classification combined the polarization and texture characteristics.The results showed that this new texture feature factor-RK can overcome the above drawbacks and can achieve same performance compared with GLCM method.
Plk1 Inhibition Causes Post-Mitotic DNA Damage and Senescence in a Range of Human Tumor Cell Lines
Bowman, Doug; Shinde, Vaishali; Lasky, Kerri; Shi, Judy; Vos, Tricia; Stringer, Bradley; Amidon, Ben; D'Amore, Natalie; Hyer, Marc L.
Plk1 is a checkpoint protein whose role spans all of mitosis and includes DNA repair, and is highly conserved in eukaryotes from yeast to man. Consistent with this wide array of functions for Plk1, the cellular consequences of Plk1 disruption are diverse, spanning delays in mitotic entry, mitotic spindle abnormalities, and transient mitotic arrest leading to mitotic slippage and failures in cytokinesis. In this work, we present the in vitro and in vivo consequences of Plk1 inhibition in cancer cells using potent, selective small-molecule Plk1 inhibitors and Plk1 genetic knock-down approaches. We demonstrate for the first time that cellular senescence is the predominant outcome of Plk1 inhibition in some cancer cell lines, whereas in other cancer cell lines the dominant outcome appears to be apoptosis, as has been reported in the literature. We also demonstrate strong induction of DNA double-strand breaks in all six lines examined (as assayed by γH2AX), which occurs either during mitotic arrest or mitotic-exit, and may be linked to the downstream induction of senescence. Taken together, our findings expand the view of Plk1 inhibition, demonstrating the occurrence of a non-apoptotic outcome in some settings. Our findings are also consistent with the possibility that mitotic arrest observed as a result of Plk1 inhibition is at least partially due to the presence of unrepaired double-strand breaks in mitosis. These novel findings may lead to alternative strategies for the development of novel therapeutic agents targeting Plk1, in the selection of biomarkers, patient populations, combination partners and dosing regimens. PMID:25365521
Activation of JNK triggers release of Brd4 from mitotic chromosomes and mediates protection from drug-induced mitotic stress.
Nishiyama, Akira; Dey, Anup; Tamura, Tomohiko; Ko, Minoru; Ozato, Keiko
Some anti-cancer drugs, including those that alter microtubule dynamics target mitotic cells and induce apoptosis in some cell types. However, such drugs elicit protective responses in other cell types allowing cells to escape from drug-induced mitotic inhibition. Cells with a faulty protective mechanism undergo defective mitosis, leading to genome instability. Brd4 is a double bromodomain protein that remains on chromosomes during mitosis. However, Brd4 is released from mitotic chromosomes when cells are exposed to anti-mitotic drugs including nocodazole. Neither the mechanisms, nor the biological significance of drug-induced Brd4 release has been fully understood. We found that deletion of the internal C-terminal region abolished nocodazole induced Brd4 release from mouse P19 cells. Furthermore, cells expressing truncated Brd4, unable to dissociate from chromosomes were blocked from mitotic progression and failed to complete cell division. We also found that pharmacological and peptide inhibitors of the c-jun-N-terminal kinases (JNK) pathway, but not inhibitors of other MAP kinases, prevented release of Brd4 from chromosomes. The JNK inhibitor that blocked Brd4 release also blocked mitotic progression. Further supporting the role of JNK in Brd4 release, JNK2-/- embryonic fibroblasts were defective in Brd4 release and sustained greater inhibition of cell growth after nocodazole treatment. In sum, activation of JNK pathway triggers release of Brd4 from chromosomes upon nocodazole treatment, which mediates a protective response designed to minimize drug-induced mitotic stress.
Comparative diagnostic and prognostic performances of the hematoxylin-eosin and phospho-histone H3 mitotic count and Ki-67 index in adrenocortical carcinoma.
Duregon, Eleonora; Molinaro, Luca; Volante, Marco; Ventura, Laura; Righi, Luisella; Bolla, Stefania; Terzolo, Massimo; Sapino, Anna; Papotti, Mauro G
Mitotic count on hematoxylin and eosin slides is a fundamental morphological criterion in the diagnosis and grading of adrenocortical carcinoma in any scoring system employed. Moreover, it is the unique term strongly associated with patient's prognosis. Phospho-histone H3 is a mitosis-specific antibody, which was already proven to facilitate mitotic count in melanoma and other tumors. Therefore, a study was designed to assess the diagnostic and prognostic role of phospho-histone H3 in 52 adrenocortical carcinomas, comparing manual and computerized count to standard manual hematoxylin- and eosin-based method and Ki-67 index. Manual hematoxylin and eosin and phospho-histone H3 mitotic counts were highly correlated (r=0.9077, P<0.0001), better than computer-assisted phospho-histone H3 evaluations, and had an excellent inter-observer reproducibility at Bland-Altman analysis. Three of 15 cases having <5 mitotic figures per 50 high-power fields by standard count on hematoxylin and eosin gained the mitotic figure point of Weiss Score after a manual count on phospho-histone H3 slides. Traditional mitotic count confirmed to be a strong predictor of overall survival (P=0.0043), better than phospho-histone H3-based evaluation (P=0.051), but not as strong as the Ki-67 index (P<0.0001). The latter further segregated adrenocortical carcinomas into three prognostic groups, stratifying cases by low (<20%), intermediate (20-50%), and high (>50%) Ki-67 values. We conclude that (a) phospho-histone H3 staining is a useful diagnostic complementary tool to standard hematoxylin and eosin mitotic count, enabling optimal mitotic figure evaluation (including atypical mitotic figures) even in adrenocortical carcinomas with a low mitotic index and with a very high reproducibility; (b) Ki-67 proved to be the best prognostic indicator of overall survival, being superior to the mitotic index, irrespective of the method (standard on hematoxylin and eosin or phospho-histone H3-based) used to count
Application of high-dimensional feature selection: evaluation for genomic prediction in man.
Bermingham, M L; Pong-Wong, R; Spiliopoulou, A; Hayward, C; Rudan, I; Campbell, H; Wright, A F; Wilson, J F; Agakov, F; Navarro, P; Haley, C S
In this study, we investigated the effect of five feature selection approaches on the performance of a mixed model (G-BLUP) and a Bayesian (Bayes C) prediction method. We predicted height, high density lipoprotein cholesterol (HDL) and body mass index (BMI) within 2,186 Croatian and into 810 UK individuals using genome-wide SNP data. Using all SNP information Bayes C and G-BLUP had similar predictive performance across all traits within the Croatian data, and for the highly polygenic traits height and BMI when predicting into the UK data. Bayes C outperformed G-BLUP in the prediction of HDL, which is influenced by loci of moderate size, in the UK data. Supervised feature selection of a SNP subset in the G-BLUP framework provided a flexible, generalisable and computationally efficient alternative to Bayes C; but careful evaluation of predictive performance is required when supervised feature selection has been used.
Using Mobile Laser Scanning Data for Features Extraction of High Accuracy Driving Maps
NASA Astrophysics Data System (ADS)
Yang, Bisheng; Liu, Yuan; Liang, Fuxun; Dong, Zhen
High Accuracy Driving Maps (HADMs) are the core component of Intelligent Drive Assistant Systems (IDAS), which can effectively reduce the traffic accidents due to human error and provide more comfortable driving experiences. Vehicle-based mobile laser scanning (MLS) systems provide an efficient solution to rapidly capture three-dimensional (3D) point clouds of road environments with high flexibility and precision. This paper proposes a novel method to extract road features (e.g., road surfaces, road boundaries, road markings, buildings, guardrails, street lamps, traffic signs, roadside-trees, power lines, vehicles and so on) for HADMs in highway environment. Quantitative evaluations show that the proposed algorithm attains an average precision and recall in terms of 90.6% and 91.2% in extracting road features. Results demonstrate the efficiencies and feasibilities of the proposed method for extraction of road features for HADMs.
Fluorescence in situ hybridization with Bacterial Artificial Chromosomes (BACs) to mitotic heterochromatin of Drosophila.
Accardo, Maria Carmela; Dimitri, Patrizio
The organization of eukaryotic chromosomes into euchromatin and heterochromatin represents an enigmatic aspect of genome evolution. Constitutive heterochromatin is a basic, yet still poorly understood component of eukaryotic genomes and its molecular characterization by means of standard genomic approaches is intrinsically difficult. Drosophila melanogaster polytene chromosomes do not seem to be particularly useful to map heterochromatin sequences because the typical features of heterochromatin, organized as it is into a chromocenter, limit cytogenetic analysis. In contrast, constitutive heterochromatin has been well-defined at the cytological level in mitotic chromosomes of neuroblasts and has been subdivided into several bands with differential staining properties. Fluorescence in situ hybridization (FISH) using Bacterial Artificial Chromosomes (BAC) probes that carry large genomic portions defined by sequence annotation has yielded a "revolution" in the field of cytogenetics because it has allowed the mapping of multiple genes at once, thus rendering constitutive heterochromatin amenable to easy and fast cytogenetics analyses. Indeed, BAC-based FISH approaches on Drosophila mitotic chromosomes have made it possible to correlate genomic sequences to their cytogenetic location, aiming to build an integrated map of the pericentric heterochromatin. This chapter presents our standard protocols for BAC-based FISH, aimed at mapping large chromosomal regions of mitotic heterochromatin in Drosophila melanogaster.
Scalable High-Performance Image Registration Framework by Unsupervised Deep Feature Representations Learning.
Wu, Guorong; Kim, Minjeong; Wang, Qian; Munsell, Brent C; Shen, Dinggang
Feature selection is a critical step in deformable image registration. In particular, selecting the most discriminative features that accurately and concisely describe complex morphological patterns in image patches improves correspondence detection, which in turn improves image registration accuracy. Furthermore, since more and more imaging modalities are being invented to better identify morphological changes in medical imaging data, the development of deformable image registration method that scales well to new image modalities or new image applications with little to no human intervention would have a significant impact on the medical image analysis community. To address these concerns, a learning-based image registration framework is proposed that uses deep learning to discover compact and highly discriminative features upon observed imaging data. Specifically, the proposed feature selection method uses a convolutional stacked autoencoder to identify intrinsic deep feature representations in image patches. Since deep learning is an unsupervised learning method, no ground truth label knowledge is required. This makes the proposed feature selection method more flexible to new imaging modalities since feature representations can be directly learned from the observed imaging data in a very short amount of time. Using the LONI and ADNI imaging datasets, image registration performance was compared to two existing state-of-the-art deformable image registration methods that use handcrafted features. To demonstrate the scalability of the proposed image registration framework, image registration experiments were conducted on 7.0-T brain MR images. In all experiments, the results showed that the new image registration framework consistently demonstrated more accurate registration results when compared to state of the art.
Scalable High Performance Image Registration Framework by Unsupervised Deep Feature Representations Learning
Wu, Guorong; Kim, Minjeong; Wang, Qian; Munsell, Brent C.
Feature selection is a critical step in deformable image registration. In particular, selecting the most discriminative features that accurately and concisely describe complex morphological patterns in image patches improves correspondence detection, which in turn improves image registration accuracy. Furthermore, since more and more imaging modalities are being invented to better identify morphological changes in medical imaging data,, the development of deformable image registration method that scales well to new image modalities or new image applications with little to no human intervention would have a significant impact on the medical image analysis community. To address these concerns, a learning-based image registration framework is proposed that uses deep learning to discover compact and highly discriminative features upon observed imaging data. Specifically, the proposed feature selection method uses a convolutional stacked auto-encoder to identify intrinsic deep feature representations in image patches. Since deep learning is an unsupervised learning method, no ground truth label knowledge is required. This makes the proposed feature selection method more flexible to new imaging modalities since feature representations can be directly learned from the observed imaging data in a very short amount of time. Using the LONI and ADNI imaging datasets, image registration performance was compared to two existing state-of-the-art deformable image registration methods that use handcrafted features. To demonstrate the scalability of the proposed image registration framework image registration experiments were conducted on 7.0-tesla brain MR images. In all experiments, the results showed the new image registration framework consistently demonstrated more accurate registration results when compared to state-of-the-art. PMID:26552069
Assessing Teaching Practicum Reflections: Distinguishing Discourse Features of the "High" and "Low" Grade Reports
ERIC Educational Resources Information Center
Luk, Jasmine
Using reflective journals to promote learning has been a common practice in the teaching profession. How learners present reflections in what are judged to be high-quality reflective writing remains under-researched. This paper explores the discourse features of teaching practicum reflective reports written by six pre-service student teachers of…
Access, Participation, and Supports: The Defining Features of High-Quality Inclusion
ERIC Educational Resources Information Center
Buysse, Virginia
This article describes current knowledge about early childhood inclusion, summarizing research and the DEC/NAEYC joint position statement on inclusion. The article also describes effective or promising educational practices that promote access, participation, and supports--the defining features of high-quality inclusion. Future efforts to improve…
Assessing Motor Skills as a Differentiating Feature between High Functioning Autism and Asperger's Disorder
ERIC Educational Resources Information Center
Cid, Maria R.
The purpose of this research was to investigate if motor skills could be used as a differentiating feature between Asperger's Disorder (AD) and High Functioning (HFA) in children under the age of 9 years, 0 months, in order to provide additional information regarding the usefulness and validity of distinguishing these two disorders. There is…
Fulton, Chandler; Kane, R. E.; Stephens, R. E.
An antiserum to flagellar axonemes from sperm of Arbacia punctulata contains antibodies which react both with intact flagellar outer fibers and with purified tubulin from the outer fibers. Immunodiffusion tests indicate the presence of similar antigenic determinants on outer-fiber tubulins from sperm flagella of five species of sea urchins and a sand dollar, but not a starfish. The antibodies also react with extracts containing tubulins from different classes of microtubules, including central-pair fibers and both A- and B-subfibers from outer fibers of sperm flagella, an extract from unfertilized eggs, mitotic apparatuses from first cleavage embryos, and cilia from later embryos. Though most tubulins tested share similar antigenic determinants, some clear differences have been detected, even, in Pseudoboletia indiana, between the outer-fiber tubulins of sperm flagella and blastular cilia. Though tubulins are "actin-like" proteins, antitubulin serum does not react with actin from sea urchin lantern muscle. On the basis of these observations, we suggest that various echinoid microtubules are built of similar, but not identical, tubulins. PMID:4106543
Physical limits on kinesin-5–mediated chromosome congression in the smallest mitotic spindles
McCoy, Kelsey M.; Tubman, Emily S.; Claas, Allison; Tank, Damien; Clancy, Shelly Applen; O'Toole, Eileen T.; Berman, Judith; Odde, David J.
A characteristic feature of mitotic spindles is the congression of chromosomes near the spindle equator, a process mediated by dynamic kinetochore microtubules. A major challenge is to understand how precise, submicrometer-scale control of kinetochore microtubule dynamics is achieved in the smallest mitotic spindles, where the noisiness of microtubule assembly/disassembly will potentially act to overwhelm the spatial information that controls microtubule plus end–tip positioning to mediate congression. To better understand this fundamental limit, we conducted an integrated live fluorescence, electron microscopy, and modeling analysis of the polymorphic fungal pathogen Candida albicans, which contains one of the smallest known mitotic spindles (<1 μm). Previously, ScCin8p (kinesin-5 in Saccharomyces cerevisiae) was shown to mediate chromosome congression by promoting catastrophe of long kinetochore microtubules (kMTs). Using C. albicans yeast and hyphal kinesin-5 (Kip1p) heterozygotes (KIP1/kip1∆), we found that mutant spindles have longer kMTs than wild-type spindles, consistent with a less-organized spindle. By contrast, kinesin-8 heterozygous mutant (KIP3/kip3∆) spindles exhibited the same spindle organization as wild type. Of interest, spindle organization in the yeast and hyphal states was indistinguishable, even though yeast and hyphal cell lengths differ by two- to fivefold, demonstrating that spindle length regulation and chromosome congression are intrinsic to the spindle and largely independent of cell size. Together these results are consistent with a kinesin-5–mediated, length-dependent depolymerase activity that organizes chromosomes at the spindle equator in C. albicans to overcome fundamental noisiness in microtubule self-assembly. More generally, we define a dimensionless number that sets a fundamental physical limit for maintaining congression in small spindles in the face of assembly noise and find that C. albicans operates very close to
Do amount of variant differentiation and mitotic rate in bladder cancer change with neoadjuvant chemotherapy?
Shen, Helen M; D'Souza, Amber M; Green, Ian F; Pohar, Kamal S; Mortazavi, Amir; Zynger, Debra L
Neoadjuvant chemotherapy (NAC) is currently recommended to all candidate patients with muscularis propria-invasive bladder cancer. However, NAC is effective in only a subset of patients, and predictors of response are lacking. Our study aimed to characterize tumoral changes with NAC usage and to identify features at bladder biopsy/transurethral resection (Bx/TUR) that may predict response. A retrospective search was performed to identify patients with bladder cancer that were pT2 at Bx/TUR upon whom a radical cystectomy (RC) was performed from 2007 to 2010. A blinded slide review of the Bx/TUR and RC was conducted. Presence, type, percent of tumor variant morphology, and tumoral mitotic rate were assessed. Ninety RC patients with slides available were identified (46 NAC, 44 non-NAC). In NAC-treated patients, there was a significantly higher percentage of nonurothelial variant differentiation in the RC compared with Bx/TUR, whereas there was no difference in the non-NAC subgroup. Percent variant differentiation at Bx/TUR was not a predictor of response. There was a significant decrease in mitotic rate between Bx/TUR and RC in NAC patients, whereas there was no difference in the non-NAC subgroup, although mitotic rate was not a predictor of response. In conclusion, percent variant differentiation and mitotic rate changed significantly from Bx/TUR to RC with NAC usage, although neither predicted response. Pathologists should be aware that variant differentiation is common in bladder cancer, with increased presence after NAC, in order to improve recognition and documentation of these findings.
Mitotic apparatus: the selective extraction of protein with mild acid.
Bibring, T; Baxandall, J
The treatment of isolated mitotic apparatus with mild (pH 3) hydrochloric acid results in the extraction of less than 10 percent of its protein, accompanied by the selective morphological disappearance of the microtubules. The same extraction can be shown to dissolve outer doublet microtubules from sperm flagella. A protein with points of similarity to the flagellar microtubule protein is the major component of the extract from mitotic apparatus.
Features of Intermetallic Alloy TNM-B1 High-Temperature Oxidation
NASA Astrophysics Data System (ADS)
Smyslov, A. M.; Bybin, A. A.; Dautov, S. S.
Features of intermetallic alloy based on titanium aluminide high-temperature oxidation at 800 - 850°C are studied. A mathematical dependence is obtained for oxidation rate on test duration. The structure and composition of an oxide layer formed during high-temperature oxidation are studied. It is shown that under operating conditions at the maximum working temperatures the intermetallic alloy exhibits low heat resistance.
Feature of high flux engineering test reactor and its role in nuclear power development
Guangquan, L.
The High Flux Engineering Test Reactor (HFETR) designed and built by China own efforts reached to its initial criticality on Dec. 27, 1979, and then achieved high power operation on Dec. 16, 1980. Until Nov. 11, 1986, the reactor had been operated for thirteen cycles. The paper presents briefly main feature of HFETR and its utilization during past years. The paper also deals with its role in nuclear power development. Finally, author gives his opinion on comprehensive utilization of HFETR.
Airborne LIDAR and high resolution satellite data for rapid 3D feature extraction
NASA Astrophysics Data System (ADS)
Jawak, S. D.; Panditrao, S. N.; Luis, A. J.
This work uses the canopy height model (CHM) based workflow for individual tree crown delineation and 3D feature extraction approach (Overwatch Geospatial's proprietary algorithm) for building feature delineation from high-density light detection and ranging (LiDAR) point cloud data in an urban environment and evaluates its accuracy by using very high-resolution panchromatic (PAN) (spatial) and 8-band (multispectral) WorldView-2 (WV-2) imagery. LiDAR point cloud data over San Francisco, California, USA, recorded in June 2010, was used to detect tree and building features by classifying point elevation values. The workflow employed includes resampling of LiDAR point cloud to generate a raster surface or digital terrain model (DTM), generation of a hill-shade image and an intensity image, extraction of digital surface model, generation of bare earth digital elevation model (DEM) and extraction of tree and building features. First, the optical WV-2 data and the LiDAR intensity image were co-registered using ground control points (GCPs). The WV-2 rational polynomial coefficients model (RPC) was executed in ERDAS Leica Photogrammetry Suite (LPS) using supplementary *.RPB file. In the second stage, ortho-rectification was carried out using ERDAS LPS by incorporating well-distributed GCPs. The root mean square error (RMSE) for the WV-2 was estimated to be 0.25 m by using more than 10 well-distributed GCPs. In the second stage, we generated the bare earth DEM from LiDAR point cloud data. In most of the cases, bare earth DEM does not represent true ground elevation. Hence, the model was edited to get the most accurate DEM/ DTM possible and normalized the LiDAR point cloud data based on DTM in order to reduce the effect of undulating terrain. We normalized the vegetation point cloud values by subtracting the ground points (DEM) from the LiDAR point cloud. A normalized digital surface model (nDSM) or CHM was calculated from the LiDAR data by subtracting the DEM from the DSM
Fully functional global genome repair of (6-4) photoproducts and compromised transcription-coupled repair of cyclobutane pyrimidine dimers in condensed mitotic chromatin
Komura, Jun-ichiro; Ikehata, Hironobu; Mori, Toshio; Ono, Tetsuya
During mitosis, chromatin is highly condensed, and activities such as transcription and semiconservative replication do not occur. Consequently, the condensed condition of mitotic chromatin is assumed to inhibit DNA metabolism by impeding the access of DNA-transacting proteins. However, about 40 years ago, several researchers observed unscheduled DNA synthesis in UV-irradiated mitotic chromosomes, suggesting the presence of excision repair. We re-examined this subject by directly measuring the removal of UV-induced DNA lesions by an ELISA and by a Southern-based technique in HeLa cells arrested at mitosis. We observed that the removal of (6-4) photoproducts from the overall genome in mitotic cells was as efficient as in interphase cells. This suggests that global genome repair of (6-4) photoproducts is fully functional during mitosis, and that the DNA in mitotic chromatin is accessible to proteins involved in this mode of DNA repair. Nevertheless, not all modes of DNA repair seem fully functional during mitosis. We also observed that the removal of cyclobutane pyrimidine dimers from the dihydrofolate reductase and c-MYC genes in mitotic cells was very slow. This suggests that transcription-coupled repair of cyclobutane pyrimidine dimers is compromised or non-functional during mitosis, which is probably the consequence of mitotic transcriptional repression. -- Highlights: Black-Right-Pointing-Pointer Global genome repair of (6-4) photoproducts is fully active in mitotic cells. Black-Right-Pointing-Pointer DNA in condensed mitotic chromatin does not seem inaccessible or inert. Black-Right-Pointing-Pointer Mitotic transcriptional repression may impair transcription-coupled repair.
Prognostic significance of the mitotic index using the mitosis marker anti-phosphohistone H3 in meningiomas.
Kim, Yoo-Jin; Ketter, Ralf; Steudel, Wolf-Ingo; Feiden, Wolfgang
Mitotic activity is one of the most reliable prognostic factors in meningiomas. The identification of mitotic figures (MFs) and the areas of highest mitotic activity in H&E-stained slides is a tedious and subjective task. Therefore, we compared the results from immunostaining for the mitosis-specific antibody anti-phosphohistone H3 (PHH3 mitotic index [MI]) with standard MF counts (H&E MI) and the Ki-67 labeling index (LI). The relationship between these proliferation indices and prognosis was investigated in a retrospective series of 265 meningiomas. The PHH3 staining method yielded greater sensitivity in the detection of MFs and facilitated MF counting. Mitotic thresholds of H&E MI of 4 or more per 10 high-power fields (HPF) and PHH3 MI of 6 or more per 10 HPF were found as the most appropriate prognostic cutoff values for the prediction of recurrence-free survival. All 3 proliferation indices were univariately associated with recurrences and deaths. In contrast with the Ki-67 LI, H&E MI and PHH3 MI also remained as independent predictors in the multivariate Cox hazards modeling (P = .0007 and P = .0004, respectively).
Micromechanical-biochemical studies of mitotic chromosome elasticity and structure
NASA Astrophysics Data System (ADS)
Poirier, Michael Guy
The structure of mitotic chromosomes was studied by combining micromechanical force measurements with microfluidic biochemical exposures. Our method is to use glass micropipettes attached to either end of a single chromosome to do mechanical experiments in the extracellular buffer. A third pipette can be used to locally 'spray' reactants so as to carry out dynamical mechanical-chemical experiments. The following elastic properties of mitotic chromosomes are found: Young's modulus, Y = 300 Pa; Poisson ratio, sigma = 0.1; Bending rigidity, B = 1 x 10 -22 J·m; Internal viscosity, eta' = 100 kg/m·sec; Volume fraction, ϕ = 0.7; Extensions of less than 3 times the relaxed length are linear and reversible; Extensions beyond 30 fold exhibit a force plateau at 15 nN and convert the chromosome to a disperse ghost-like state with little change in chromatin structure; Mitotic chromosomes are relatively isotropic; dsDNA cuts of at least every 3 kb cause the a mitotic chromosomes to fall apart; dsDNA cuts less frequently than every 50 kb do not affect mitotic chromosome structure. These results lead to the conclusion that mitotic chromosomes are a network crosslinked every 50 kb between which chromatin is fold by chromatin folding proteins, which are likely to be condensins.
Timeless links replication termination to mitotic kinase activation.
Dheekollu, Jayaraju; Wiedmer, Andreas; Hayden, James; Speicher, David; Gotter, Anthony L; Yen, Tim; Lieberman, Paul M
The mechanisms that coordinate the termination of DNA replication with progression through mitosis are not completely understood. The human Timeless protein (Tim) associates with S phase replication checkpoint proteins Claspin and Tipin, and plays an important role in maintaining replication fork stability at physical barriers, like centromeres, telomeres and ribosomal DNA repeats, as well as at termination sites. We show here that human Tim can be isolated in a complex with mitotic entry kinases CDK1, Auroras A and B, and Polo-like kinase (Plk1). Plk1 bound Tim directly and colocalized with Tim at a subset of mitotic structures in M phase. Tim depletion caused multiple mitotic defects, including the loss of sister-chromatid cohesion, loss of mitotic spindle architecture, and a failure to exit mitosis. Tim depletion caused a delay in mitotic kinase activity in vivo and in vitro, as well as a reduction in global histone H3 S10 phosphorylation during G2/M phase. Tim was also required for the recruitment of Plk1 to centromeric DNA and formation of catenated DNA structures at human centromere alpha satellite repeats. Taken together, these findings suggest that Tim coordinates mitotic kinase activation with termination of DNA replication.
A comprehensive analysis of earthquake damage patterns using high dimensional model representation feature selection
NASA Astrophysics Data System (ADS)
Taşkin Kaya, Gülşen
Recently, earthquake damage assessment using satellite images has been a very popular ongoing research direction. Especially with the availability of very high resolution (VHR) satellite images, a quite detailed damage map based on building scale has been produced, and various studies have also been conducted in the literature. As the spatial resolution of satellite images increases, distinguishability of damage patterns becomes more cruel especially in case of using only the spectral information during classification. In order to overcome this difficulty, textural information needs to be involved to the classification to improve the visual quality and reliability of damage map. There are many kinds of textural information which can be derived from VHR satellite images depending on the algorithm used. However, extraction of textural information and evaluation of them have been generally a time consuming process especially for the large areas affected from the earthquake due to the size of VHR image. Therefore, in order to provide a quick damage map, the most useful features describing damage patterns needs to be known in advance as well as the redundant features. In this study, a very high resolution satellite image after Iran, Bam earthquake was used to identify the earthquake damage. Not only the spectral information, textural information was also used during the classification. For textural information, second order Haralick features were extracted from the panchromatic image for the area of interest using gray level co-occurrence matrix with different size of windows and directions. In addition to using spatial features in classification, the most useful features representing the damage characteristic were selected with a novel feature selection method based on high dimensional model representation (HDMR) giving sensitivity of each feature during classification. The method called HDMR was recently proposed as an efficient tool to capture the input
High-Precision Registration of Point Clouds Based on Sphere Feature Constraints.
Huang, Junhui; Wang, Zhao; Gao, Jianmin; Huang, Youping; Towers, David Peter
Point cloud registration is a key process in multi-view 3D measurements. Its precision affects the measurement precision directly. However, in the case of the point clouds with non-overlapping areas or curvature invariant surface, it is difficult to achieve a high precision. A high precision registration method based on sphere feature constraint is presented to overcome the difficulty in the paper. Some known sphere features with constraints are used to construct virtual overlapping areas. The virtual overlapping areas provide more accurate corresponding point pairs and reduce the influence of noise. Then the transformation parameters between the registered point clouds are solved by an optimization method with weight function. In that case, the impact of large noise in point clouds can be reduced and a high precision registration is achieved. Simulation and experiments validate the proposed method.
High-Precision Registration of Point Clouds Based on Sphere Feature Constraints
Huang, Junhui; Wang, Zhao; Gao, Jianmin; Huang, Youping; Towers, David Peter
Point cloud registration is a key process in multi-view 3D measurements. Its precision affects the measurement precision directly. However, in the case of the point clouds with non-overlapping areas or curvature invariant surface, it is difficult to achieve a high precision. A high precision registration method based on sphere feature constraint is presented to overcome the difficulty in the paper. Some known sphere features with constraints are used to construct virtual overlapping areas. The virtual overlapping areas provide more accurate corresponding point pairs and reduce the influence of noise. Then the transformation parameters between the registered point clouds are solved by an optimization method with weight function. In that case, the impact of large noise in point clouds can be reduced and a high precision registration is achieved. Simulation and experiments validate the proposed method. PMID:28042846
Uranus' Persistent Patterns and Features from High-SNR Imaging in 2012-2014
NASA Astrophysics Data System (ADS)
Fry, Patrick M.; Sromovsky, Lawrence A.; de Pater, Imke; Hammel, Heidi B.; Marcus, Phillip
Since 2012, Uranus has been the subject of an observing campaign utilizing high signal-to-noise imaging techniques at Keck Observatory (Fry et al. 2012, Astron. J. 143, 150-161). High quality observing conditions on four observing runs of consecutive nights allowed longitudinally-complete coverage of the atmosphere over a period of two years (Sromovsky et al. 2015, Icarus 258, 192-223). Global mosaic maps made from images acquired on successive nights in August 2012, November 2012, August 2013, and August 2014, show persistent patterns, and six easily distinguished long-lived cloud features, which we were able to track for long periods that ranged from 5 months to over two years. Two at similar latitudes are associated with dark spots, and move with the atmospheric zonal flow close to the location of their associated dark spot instead of following the flow at the latitude of the bright features. These features retained their morphologies and drift rates in spite of several close interactions. A second pair of features at similar latitudes also survived several close approaches. Several of the long-lived features also exhibited equatorward drifts and latitudinal oscillations. Also persistent are a remarkable near-equatorial wave feature and global zonal band structure. We will present imagery, maps, and analyses of these phenomena.PMF and LAS acknowledge support from NASA Planetary Astronomy Program; PMF and LAS acknowledge funding and technical support from W. M. Keck Observatory. We thank those of Hawaiian ancestry on whose sacred mountain we are privileged to be guests. Without their generous hospitality none of our groundbased observations would have been possible.
High velocity features in Type Ia supernovae via interaction with circumstellar shell
NASA Astrophysics Data System (ADS)
Mulligan, Brian W.; Wheeler, J. Craig
Observations of Type Ia supernovae (SN Ia) in the weeks before B-band maximum (Bmax) have shown the presence of Ca, Si, and Fe features with velocities of 8,000-14,000 km/s faster than that associated with the photospheric features (PSF). Suggestions for the source of the high velocity features include interaction of the ejecta with a circumstellar material. We perform hydrodynamic simulation of a supernova interacting with a shell consisting of 5×10-3 M⊙ of material and an outer radius of 0.028 R⊙ as well as a supernova in a low density circumstellar medium (LDCSM) without a shell. We present the synthetic spectra of the Ca II near-IR feature generated from both models fit to the observed features in SN 2011fe in the epoch before Bmax. The shell interaction model consistently fits the observed spectra better than the LDCSM model at all times before Bmax, and satisfies the observed velocity evolution of both the HVF and PSF.
High-resolution face verification using pore-scale facial features.
Li, Dong; Zhou, Huiling; Lam, Kin-Man
Face recognition methods, which usually represent face images using holistic or local facial features, rely heavily on alignment. Their performances also suffer a severe degradation under variations in expressions or poses, especially when there is one gallery per subject only. With the easy access to high-resolution (HR) face images nowadays, some HR face databases have recently been developed. However, few studies have tackled the use of HR information for face recognition or verification. In this paper, we propose a pose-invariant face-verification method, which is robust to alignment errors, using the HR information based on pore-scale facial features. A new keypoint descriptor, namely, pore-Principal Component Analysis (PCA)-Scale Invariant Feature Transform (PPCASIFT)-adapted from PCA-SIFT-is devised for the extraction of a compact set of distinctive pore-scale facial features. Having matched the pore-scale features of two-face regions, an effective robust-fitting scheme is proposed for the face-verification task. Experiments show that, with one frontal-view gallery only per subject, our proposed method outperforms a number of standard verification methods, and can achieve excellent accuracy even the faces are under large variations in expression and pose.
Chung, Sun-Ju; Hwang, Kyu-Ha; Ryu, Yoon-Hyun; Lee, Chung-Uk E-mail: firstname.lastname@example.com E-mail: firstname.lastname@example.com
Current microlensing follow-up observations focus on high-magnification events because of the high efficiency of planet detection. However, central perturbations of high-magnification events caused by a planet can also be produced by a very close or a very wide binary companion, and the two kinds of central perturbations are not generally distinguished without time consuming detailed modeling (a planet-binary degeneracy). Hence, it is important to resolve the planet-binary degeneracy that occurs in high-magnification events. In this paper, we investigate caustic-crossing high-magnification events caused by a planet and a wide binary companion. From this investigation, we find that because of the different magnification excess patterns inside the central caustics induced by the planet and the binary companion, the light curves of the caustic-crossing planetary-lensing events exhibit a feature that is discriminated from those of the caustic-crossing binary-lensing events, and the feature can be used to immediately distinguish between the planetary and binary companions. The planetary-lensing feature appears in the interpeak region between the two peaks of the caustic-crossings. The structure of the interpeak region for the planetary-lensing events is smooth and convex or boxy, whereas the structure for the binary-lensing events is smooth and concave. We also investigate the effect of a finite background source star on the planetary-lensing feature in the caustic-crossing high-magnification events. From this, we find that the convex-shaped interpeak structure appears in a certain range that changes with the mass ratio of the planet to the planet-hosting star.
Dynamic Positioning of Mitotic Spindles in Yeast:
Yeh, Elaine; Yang, Charlie; Chin, Elaine; Maddox, Paul; Salmon, E. D.; Lew, Daniel J.; Bloom, Kerry
In the budding yeast Saccharomyces cerevisiae, movement of the mitotic spindle to a predetermined cleavage plane at the bud neck is essential for partitioning chromosomes into the mother and daughter cells. Astral microtubule dynamics are critical to the mechanism that ensures nuclear migration to the bud neck. The nucleus moves in the opposite direction of astral microtubule growth in the mother cell, apparently being "pushed" by microtubule contacts at the cortex. In contrast, microtubules growing toward the neck and within the bud promote nuclear movement in the same direction of microtubule growth, thus "pulling" the nucleus toward the bud neck. Failure of "pulling" is evident in cells lacking Bud6p, Bni1p, Kar9p, or the kinesin homolog, Kip3p. As a consequence, there is a loss of asymmetry in spindle pole body segregation into the bud. The cytoplasmic motor protein, dynein, is not required for nuclear movement to the neck; rather, it has been postulated to contribute to spindle elongation through the neck. In the absence of KAR9, dynein-dependent spindle oscillations are evident before anaphase onset, as are postanaphase dynein-dependent pulling forces that exceed the velocity of wild-type spindle elongation threefold. In addition, dynein-mediated forces on astral microtubules are sufficient to segregate a 2N chromosome set through the neck in the absence of spindle elongation, but cytoplasmic kinesins are not. These observations support a model in which spindle polarity determinants (BUD6, BNI1, KAR9) and cytoplasmic kinesin (KIP3) provide directional cues for spindle orientation to the bud while restraining the spindle to the neck. Cytoplasmic dynein is attenuated by these spindle polarity determinants and kinesin until anaphase onset, when dynein directs spindle elongation to distal points in the mother and bud. PMID:11071919
Assessment of Mitotic Activity in Pituitary Adenomas and Carcinomas.
Thapar, Kamal; Yamada, Yukio; Scheithauer, Bernd; Kovacs, Kalman; Yamada, Shozo; Stefaneanu, Lucia
Assessment of mitotic activity represents one of the oldest and most routinely used histopathologic methods of evaluating the biological aggressiveness of human tumors. In the case of pituitary tumors, however, the relevance of this approach as a means of gauging tumor behavior remains ill-defined. In this article, the relationship between the mitotic index and biological aggressiveness of pituitary tumors was evaluated in a series of 54 pituitary adenomas and 6 primary pituitary carcinomas. All tumors were fully classified by immunohistochemistry and electron microscopy; adenomas were further stratified on the basis of their invasion status, the latter being defined as gross, operatively, or radiologically apparent infiltration of dura or bone. Mitotic figures were present in 11 tumors, 10 being either invasive adenomas or pituitary carcinomas. A significant association between the presence of mitotic figures and tumor behavior was noted, as evidenced by progressive increments in the proportion of cases expressing mitotic figures in the categories of noninvasive adenoma, invasive adenoma, and pituitary carcinoma (3.9, 21.4, and 66.7%, respectively; Fisher's exact test, two-tailed, p < 0.001). The mitotic index, however, appeared to be a less informative parameter, being extremely low in all cases (mean = 0.016% +/- 0.005 [+/- SEMI). Although the mean mitotic index in pituitary carcinomas (0.09% +/- 0.035) was significantly higher than the mean mitotic index of either noninvasive adenomas (0.002% +/- 0.002) or invasive adenomas (0.013% +/- 0.005), no practical threshold value capable of distinguishing these three groups was evident. Comparison of the mitotic index with Ki-67 derived growth fractions in these tumors revealed a significant but weak linear correlation (r = 0.41, p < 0.01). These data suggest that when, mitotic figures are present, they do provide some indication of the behavior and invasive potential of pituitary tumors. For routine diagnostic
Detection of Harbours from High Resolution Remote Sensing Imagery via Saliency Analysis and Feature Learning
NASA Astrophysics Data System (ADS)
Wang, Yetianjian; Pan, Li; Wang, Dagang; Kang, Yifei
Harbours are very important objects in civil and military fields. To detect them from high resolution remote sensing imagery is important in various fields and also a challenging task. Traditional methods of detecting harbours mainly focus on the segmentation of water and land and the manual selection of knowledge. They do not make enough use of other features of remote sensing imagery and often fail to describe the harbours completely. In order to improve the detection, a new method is proposed. First, the image is transformed to Hue, Saturation, Value (HSV) colour space and saliency analysis is processed via the generation and enhancement of the co-occurrence histogram to help detect and locate the regions of interest (ROIs) that is salient and may be parts of the harbour. Next, SIFT features are extracted and feature learning is processed to help represent the ROIs. Then, by using classified feature of the harbour, a classifier is trained and used to check the ROIs to find whether they belong to the harbour. Finally, if the ROIs belong to the harbour, a minimum bounding rectangle is formed to include all the harbour ROIs and detect and locate the harbour. The experiment on high resolution remote sensing imagery shows that the proposed method performs better than other methods in precision of classifying ROIs and accuracy of completely detecting and locating harbours.
High-fidelity conformation of graphene to SiO2 topographic features.
Cullen, W G; Yamamoto, M; Burson, K M; Chen, J H; Jang, C; Li, L; Fuhrer, M S; Williams, E D
High-resolution noncontact atomic force microscopy of SiO2 reveals previously unresolved roughness at the few-nm length scale, and scanning tunneling microscopy of graphene on SiO2 shows graphene to be slightly smoother than the supporting SiO2 substrate. A quantitative energetic analysis explains the observed roughness of graphene on SiO2 as extrinsic, and a natural result of highly conformal adhesion. Graphene conforms to the substrate down to the smallest features with nearly 99% fidelity, indicating conformal adhesion can be highly effective for strain engineering of graphene.
High-Velocity Absorption Features in FUSE Spectra of Eta Carinae
NASA Technical Reports Server (NTRS)
Sonneborn, G.; Iping, R. C.; Gull, T. R.; Vieira, G.
Numerous broad (200 to 1000 km/sec) features in the FUSE spectrum (905-1187 A) of eta Carinae are identified as absorption by a forest of high-velocity narrow lines formed in the expanding circumstellar envelope. These features were previously thought to be P-Cygni lines arising in the wind of the central star. The features span a heliocentric velocity range of -140 to -580 km/sec and are seen prominently in low-ionization ground-state transitions (e.g. N I 1134-35, Fe II 1145-42, 1133, 1127- 22, P II 1153, C I 1158) in addition to C III] 1176 A. The high-velocity components of the FUSE transitions have depths about 50% below the continuum. The identifications are consistent with the complex velocity structures seen in ground- and excited-state transitions of Mg I, Mg 11, Fe II, V II, etc observed in STIS/E230H spectra. The origin of other broad features of similar width and depth in the FUSE spectrum, but without low-velocity ISM absorption, are unidentified. However, they are suspected of being absorption of singly-ionized iron-peak elements (e.g. Fe II, V II, Cr II) out of excited levels 1,000 to 20,000 cmE-l above the ground state. The high-velocity features seen in Fe II 1145 are also present in Fe II 1608 (STIS/E140M), but are highly saturated in the latter. Since these transitions have nearly identical log (flambda) (1.998 vs. 2.080), the differences in the profiles are attributable to the different aperture sizes used (30 x 30 arcsec for FUSE, 0.2 x 0.2 arcsec for STIS/E140M). The high-velocity gas appears to be very patchy or has a small covering factor near the central star. Eta Carinae has been observed several times by FUSE over the past three years. The FUSE flux levels and spectral features in eta Car are essentially unchanged over the 2000 March to June 2002 period, establishing a baseline far-UV spectrum in advance of the predicted spectroscopic minimum in 2003.
Prognostic differences of World Health Organization-assessed mitotic activity index and mitotic impression by quick scanning in invasive ductal breast cancer patients younger than 55 years.
Skaland, Ivar; van Diest, Paul J; Janssen, Emiel A M; Gudlaugsson, Einar; Baak, Jan P A
The proliferation marker mitotic activity index is the strongest prognostic indicator in lymph node-negative breast cancer. The World Health Organization (WHO) 2003-defined procedure for determining WHO-mitotic activity index is often replaced by a quick scan mitotic impression. We evaluated the prognostic consequences of this practice in 433 T(1-3)N(0)M(0) lymph node-negative invasive ductal type breast cancers with long-term follow-up (median, 112 months; range, 12-187 months). Twenty-seven percent of the studied cases developed distant metastases, and 25% died of disease. Agreement between WHO-mitotic activity index (0-5 = 1, 6-10 = 2, >10 = 3) and mitotic impression (1, 2, 3) categories was 66% (kappa = 0.41), including 85% for category 1, 26% for category 2, and 52% for category 3. The WHO-mitotic activity index was a much stronger prognosticator than the mitotic impression, and the 10-year survival rates of the same categories (eg, mitotic activity index and mitotic impression category both 2) differed greatly. When grade was assessed by combining WHO-mitotic activity index or mitotic impression with the same values for tubular formation and nuclear atypia, grades disagreed in 18% of the cases. Deviation from the formal WHO-mitotic activity index assessment guidelines in breast cancer often results in erroneous prognosis estimations with therapeutic consequences and may explain why the prognostic value of proliferative activity in breast cancer is not always confirmed.
rough deal: a gene required for proper mitotic segregation in Drosophila
We describe a genetic locus rough deal (rod) in Drosophila melanogaster, identified by mutations that interfere with the faithful transmission of chromosomes to daughter cells during mitosis. Five mutant alleles were isolated, each associated with a similar set of mitotic abnormalities in the dividing neuroblasts of homozygous mutant larvae: high frequencies of aneuploid cells and abnormal anaphase figures, in which chromatids may lag, form bridges, or completely fail to separate. Surviving homozygous adults are sterile, and show cuticular defects associated with cell death, i.e., roughened eyes, sparse abdominal bristles, and notched wing margins. The morphological process of spermatogenesis is largely unaffected and motile sperm are produced, but meiocyte aneuploidy is common. The nature of the observed abnormalities in mitotic cells suggests that the reduced fidelity of chromosome transmission to the daughter cells is due to a failure in a mechanism involved in assuring the proper release of sister chromatids. PMID:2512302
Mcl-1 dynamics influence mitotic slippage and death in mitosis.
Sloss, Olivia; Topham, Caroline; Diez, Maria; Taylor, Stephen
Microtubule-binding drugs such as taxol are frontline treatments for a variety of cancers but exactly how they yield patient benefit is unclear. In cell culture, inhibiting microtubule dynamics prevents spindle assembly, leading to mitotic arrest followed by either apoptosis in mitosis or slippage, whereby a cell returns to interphase without dividing. Myeloid cell leukaemia-1 (Mcl-1), a pro-survival member of the Bcl-2 family central to the intrinsic apoptosis pathway, is degraded during a prolonged mitotic arrest and may therefore act as a mitotic death timer. Consistently, we show that blocking proteasome-mediated degradation inhibits taxol-induced mitotic apoptosis in a Mcl-1-dependent manner. However, this degradation does not require the activity of either APC/C-Cdc20, FBW7 or MULE, three separate E3 ubiquitin ligases implicated in targeting Mcl-1 for degradation. This therefore challenges the notion that Mcl-1 undergoes regulated degradation during mitosis. We also show that Mcl-1 is continuously synthesized during mitosis and that blocking protein synthesis accelerates taxol induced death-in-mitosis. Modulating Mcl-1 levels also influences slippage; overexpressing Mcl-1 extends the time from mitotic entry to mitotic exit in the presence of taxol, while inhibiting Mcl-1 accelerates it. We suggest that Mcl-1 competes with Cyclin B1 for binding to components of the proteolysis machinery, thereby slowing down the slow degradation of Cyclin B1 responsible for slippage. Thus, modulating Mcl-1 dynamics influences both death-in-mitosis and slippage. However, because mitotic degradation of Mcl-1 appears not to be under the control of an E3 ligase, we suggest that the notion of network crosstalk is used with caution.
PKCι depletion initiates mitotic slippage-induced senescence in glioblastoma
Restall, Ian J; Parolin, Doris A E; Daneshmand, Manijeh; Hanson, Jennifer E L; Simard, Manon A; Fitzpatrick, Megan E; Kumar, Ritesh; Lavictoire, Sylvie J; Lorimer, Ian A J
Cellular senescence is a tumor suppressor mechanism where cells enter a permanent growth arrest following cellular stress. Oncogene-induced senescence (OIS) is induced in non-malignant cells following the expression of an oncogene or inactivation of a tumor suppressor. Previously, we have shown that protein kinase C iota (PKCι) depletion induces cellular senescence in glioblastoma cells in the absence of a detectable DNA damage response. Here we demonstrate that senescent glioblastoma cells exhibit an aberrant centrosome morphology. This was observed in basal levels of senescence, in p21-induced senescence, and in PKCι depletion-induced senescence. In addition, senescent glioblastoma cells are polyploid, Ki-67 negative and arrest at the G1/S checkpoint, as determined by expression of cell cycle regulatory proteins. These markers are all consistent with cells that have undergone mitotic slippage. Failure of the spindle assembly checkpoint to function properly can lead to mitotic slippage, resulting in the premature exit of mitotic cells into the G1 phase of the cell cycle. Although in G1, these cells have the replicated DNA and centrosomal phenotype of a cell that has entered mitosis and failed to divide. Overall, we demonstrate that PKCι depletion initiates mitotic slippage-induced senescence in glioblastoma cells. To our knowledge, this is the first evidence of markers of mitotic slippage directly in senescent cells by co-staining for senescence-associated β-galactosidase and immunofluorescence markers in the same cell population. We suggest that markers of mitotic slippage be assessed in future studies of senescence to determine the extent of mitotic slippage in the induction of cellular senescence. PMID:26208522
PKCι depletion initiates mitotic slippage-induced senescence in glioblastoma.
Restall, Ian J; Parolin, Doris A E; Daneshmand, Manijeh; Hanson, Jennifer E L; Simard, Manon A; Fitzpatrick, Megan E; Kumar, Ritesh; Lavictoire, Sylvie J; Lorimer, Ian A J
Cellular senescence is a tumor suppressor mechanism where cells enter a permanent growth arrest following cellular stress. Oncogene-induced senescence (OIS) is induced in non-malignant cells following the expression of an oncogene or inactivation of a tumor suppressor. Previously, we have shown that protein kinase C iota (PKCι) depletion induces cellular senescence in glioblastoma cells in the absence of a detectable DNA damage response. Here we demonstrate that senescent glioblastoma cells exhibit an aberrant centrosome morphology. This was observed in basal levels of senescence, in p21-induced senescence, and in PKCι depletion-induced senescence. In addition, senescent glioblastoma cells are polyploid, Ki-67 negative and arrest at the G1/S checkpoint, as determined by expression of cell cycle regulatory proteins. These markers are all consistent with cells that have undergone mitotic slippage. Failure of the spindle assembly checkpoint to function properly can lead to mitotic slippage, resulting in the premature exit of mitotic cells into the G1 phase of the cell cycle. Although in G1, these cells have the replicated DNA and centrosomal phenotype of a cell that has entered mitosis and failed to divide. Overall, we demonstrate that PKCι depletion initiates mitotic slippage-induced senescence in glioblastoma cells. To our knowledge, this is the first evidence of markers of mitotic slippage directly in senescent cells by co-staining for senescence-associated β-galactosidase and immunofluorescence markers in the same cell population. We suggest that markers of mitotic slippage be assessed in future studies of senescence to determine the extent of mitotic slippage in the induction of cellular senescence.
Features of an underexpanded pulsed impact gas-dispersed jet with a high particle concentration
NASA Astrophysics Data System (ADS)
Sadin, D. V.; Lyubarskii, S. D.; Gravchenko, Yu. A.
We have reported on the results of a numerical simulation of the inflow of an underexpanded pulsed gas-dispersed jet with a high particle concentration onto a rigid obstacle unbounded in the transverse direction. The characteristic features of such interaction, in particular, the anomalous formation of the shock-wave structure of the two-phase flow at the subsonic velocity of the carrier gas and the evolution of self-sustained oscillations, have been investigated.
Fabrication of Pt nanowires with a diffraction-unlimited feature size by high-threshold lithography
Li, Li E-mail: firstname.lastname@example.com Zhang, Ziang; Yu, Miao; Song, Zhengxun; Weng, Zhankun; Wang, Zuobin E-mail: email@example.com Li, Wenjun; Wang, Dapeng; Zhao, Le; Peng, Kuiqing E-mail: firstname.lastname@example.com
Although the nanoscale world can already be observed at a diffraction-unlimited resolution using far-field optical microscopy, to make the step from microscopy to lithography still requires a suitable photoresist material system. In this letter, we consider the threshold to be a region with a width characterized by the extreme feature size obtained using a Gaussian beam spot. By narrowing such a region through improvement of the threshold sensitization to intensity in a high-threshold material system, the minimal feature size becomes smaller. By using platinum as the negative photoresist, we demonstrate that high-threshold lithography can be used to fabricate nanowire arrays with a scalable resolution along the axial direction of the linewidth from the micro- to the nanoscale using a nanosecond-pulsed laser source with a wavelength λ{sub 0} = 1064 nm. The minimal feature size is only several nanometers (sub λ{sub 0}/100). Compared with conventional polymer resist lithography, the advantages of high-threshold lithography are sharper pinpoints of laser intensity triggering the threshold response and also higher robustness allowing for large area exposure by a less-expensive nanosecond-pulsed laser.
Unbiased Prediction and Feature Selection in High-Dimensional Survival Regression
Laimighofer, Michael; Krumsiek, Jan; Theis, Fabian J.
Abstract With widespread availability of omics profiling techniques, the analysis and interpretation of high-dimensional omics data, for example, for biomarkers, is becoming an increasingly important part of clinical medicine because such datasets constitute a promising resource for predicting survival outcomes. However, early experience has shown that biomarkers often generalize poorly. Thus, it is crucial that models are not overfitted and give accurate results with new data. In addition, reliable detection of multivariate biomarkers with high predictive power (feature selection) is of particular interest in clinical settings. We present an approach that addresses both aspects in high-dimensional survival models. Within a nested cross-validation (CV), we fit a survival model, evaluate a dataset in an unbiased fashion, and select features with the best predictive power by applying a weighted combination of CV runs. We evaluate our approach using simulated toy data, as well as three breast cancer datasets, to predict the survival of breast cancer patients after treatment. In all datasets, we achieve more reliable estimation of predictive power for unseen cases and better predictive performance compared to the standard CoxLasso model. Taken together, we present a comprehensive and flexible framework for survival models, including performance estimation, final feature selection, and final model construction. The proposed algorithm is implemented in an open source R package (SurvRank) available on CRAN. PMID:26894327
Cold-treated centrosome: isolation of centrosomes from mitotic sea urchin eggs, production of an anticentrosomal antibody, and novel ultrastructural imaging.
Thompson-Coffe, C; Coffe, G; Schatten, H; Mazia, D; Schatten, G
A novel isolation of centrosomes is described and it was used to both generate a centrosome-specific monoclonal antibody and to image with high-resolution low-voltage scanning electron microscopy the surface details of the isolated centrosome. At first mitotic prometaphase, sea urchin zygotes are chilled on ice overnight. While most of the microtubules disassemble, the mitotic centrosomes collapse into aggregated masses. These centrosomes have been isolated, and used to generate a monoclonal antibody, designated 4D2, which is reactive with interphase and mitotic centrosomes. 4D2 staining of centrosomes is similar, but not identical, to that of other centrosomal antibodies like Ah6 and 5051. Centrosomal material is detected as a compact sphere after cold treatment; upon recovery the sphere expands and undergoes the shape changes previously described [Mazia et al., 1987: J. Cell Biol. 105:206a] to eventually reorganize a normal mitotic apparatus.
Mos oncogene product associates with kinetochores in mammalian somatic cells and disrupts mitotic progression.
Wang, X M; Yew, N; Peloquin, J G; Vande Woude, G F; Borisy, G G
The mos protooncogene has opposing effects on cell cycle progression. It is required for reinitiation of meiotic maturation and for meiotic progression through metaphase II, yet it is an active component of cytostatic factor. mos is a potent oncogene in fibroblasts, but high levels of expression are lethal. The lethality of mos gene expression in mammalian cells could be a consequence of a blockage induced by its cytostatic factor-related activity, which may appear at high dosage in mitotic cells. We have directly tested whether expression of the Mos protein can block mitosis in mammalian cells by microinjecting a fusion protein between Escherichia coli maltose-binding protein and Xenopus c-Mos into PtK1 epithelial cells and analyzing the cells by video time-lapse and immunofluorescence microscopy. Time-course analyses showed that Mos blocked mitosis by preventing progression to a normal metaphase. Chromosomes frequently failed to attain a bipolar orientation and were found near one pole. Injection of a kinase-deficient mutant Mos had no effect on mitosis, indicating that the blockage of mitotic progression required Mos kinase activity. Antitubulin immunostaining of cells blocked by Mos showed that microtubules were present but that spindle morphology was abnormal. Immunostaining for the Mos fusion protein showed that both wild-type and kinase mutant proteins localized at the kinetochores. Our results suggest that mitotic blockage by Mos may result from an action of the Mos kinase on the kinetochores, thus increasing chromosome instability and preventing normal congression. Images PMID:8078882
Mitotic-chromosome-based physical mapping of the Culex quinquefasciatus genome.
Naumenko, Anastasia N; Timoshevskiy, Vladimir A; Kinney, Nicholas A; Kokhanenko, Alina A; deBruyn, Becky S; Lovin, Diane D; Stegniy, Vladimir N; Severson, David W; Sharakhov, Igor V; Sharakhova, Maria V
The genome assembly of southern house mosquito Cx. quinquefasciatus is represented by a high number of supercontigs with no order or orientation on the chromosomes. Although cytogenetic maps for the polytene chromosomes of this mosquito have been developed, their utilization for the genome mapping remains difficult because of the low number of high-quality spreads in chromosome preparations. Therefore, a simple and robust mitotic-chromosome-based approach for the genome mapping of Cx. quinquefasciatus still needs to be developed. In this study, we performed physical mapping of 37 genomic supercontigs using fluorescent in situ hybridization on mitotic chromosomes from imaginal discs of 4th instar larvae. The genetic linkage map nomenclature was adopted for the chromosome numbering based on the direct positioning of 58 markers that were previously genetically mapped. The smallest, largest, and intermediate chromosomes were numbered as 1, 2, and 3, respectively. For idiogram development, we analyzed and described in detail the morphology and proportions of the mitotic chromosomes. Chromosomes were subdivided into 19 divisions and 72 bands of four different intensities. These idiograms were used for mapping the genomic supercontigs/genetic markers. We also determined the presence of length polymorphism in the q arm of sex-determining chromosome 1 in Cx. quinquefasciatus related to the size of ribosomal locus. Our physical mapping and previous genetic linkage mapping resulted in the chromosomal assignment of 13% of the total genome assembly to the chromosome bands. We provided the first detailed description, nomenclature, and idiograms for the mitotic chromosomes of Cx. quinquefasciatus. Further application of the approach developed in this study will help to improve the quality of the southern house mosquito genome.
Increased functional protein expression using nucleotide sequence features enriched in highly expressed genes in zebrafish.
Horstick, Eric J; Jordan, Diana C; Bergeron, Sadie A; Tabor, Kathryn M; Serpe, Mihaela; Feldman, Benjamin; Burgess, Harold A
Many genetic manipulations are limited by difficulty in obtaining adequate levels of protein expression. Bioinformatic and experimental studies have identified nucleotide sequence features that may increase expression, however it is difficult to assess the relative influence of these features. Zebrafish embryos are rapidly injected with calibrated doses of mRNA, enabling the effects of multiple sequence changes to be compared in vivo. Using RNAseq and microarray data, we identified a set of genes that are highly expressed in zebrafish embryos and systematically analyzed for enrichment of sequence features correlated with levels of protein expression. We then tested enriched features by embryo microinjection and functional tests of multiple protein reporters. Codon selection, releasing factor recognition sequence and specific introns and 3' untranslated regions each increased protein expression between 1.5- and 3-fold. These results suggested principles for increasing protein yield in zebrafish through biomolecular engineering. We implemented these principles for rational gene design in software for codon selection (CodonZ) and plasmid vectors incorporating the most active non-coding elements. Rational gene design thus significantly boosts expression in zebrafish, and a similar approach will likely elevate expression in other animal models.
Feature Augmentation via Nonparametrics and Selection (FANS) in High-Dimensional Classification
Feng, Yang; Jiang, Jiancheng; Tong, Xin
We propose a high dimensional classification method that involves nonparametric feature augmentation. Knowing that marginal density ratios are the most powerful univariate classifiers, we use the ratio estimates to transform the original feature measurements. Subsequently, penalized logistic regression is invoked, taking as input the newly transformed or augmented features. This procedure trains models equipped with local complexity and global simplicity, thereby avoiding the curse of dimensionality while creating a flexible nonlinear decision boundary. The resulting method is called Feature Augmentation via Nonparametrics and Selection (FANS). We motivate FANS by generalizing the Naive Bayes model, writing the log ratio of joint densities as a linear combination of those of marginal densities. It is related to generalized additive models, but has better interpretability and computability. Risk bounds are developed for FANS. In numerical analysis, FANS is compared with competing methods, so as to provide a guideline on its best application domain. Real data analysis demonstrates that FANS performs very competitively on benchmark email spam and gene expression data sets. Moreover, FANS is implemented by an extremely fast algorithm through parallel computing. PMID:27185970
Object-Based Arctic Sea Ice Feature Extraction through High Spatial Resolution Aerial photos
NASA Astrophysics Data System (ADS)
Miao, X.; Xie, H.
High resolution aerial photographs used to detect and classify sea ice features can provide accurate physical parameters to refine, validate, and improve climate models. However, manually delineating sea ice features, such as melt ponds, submerged ice, water, ice/snow, and pressure ridges, is time-consuming and labor-intensive. An object-based classification algorithm is developed to automatically extract sea ice features efficiently from aerial photographs taken during the Chinese National Arctic Research Expedition in summer 2010 (CHINARE 2010) in the MIZ near the Alaska coast. The algorithm includes four steps: (1) the image segmentation groups the neighboring pixels into objects based on the similarity of spectral and textural information; (2) the random forest classifier distinguishes four general classes: water, general submerged ice (GSI, including melt ponds and submerged ice), shadow, and ice/snow; (3) the polygon neighbor analysis separates melt ponds and submerged ice based on spatial relationship; and (4) pressure ridge features are extracted from shadow based on local illumination geometry. The producer's accuracy of 90.8% and user's accuracy of 91.8% are achieved for melt pond detection, and shadow shows a user's accuracy of 88.9% and producer's accuracies of 91.4%. Finally, pond density, pond fraction, ice floes, mean ice concentration, average ridge height, ridge profile, and ridge frequency are extracted from batch processing of aerial photos, and their uncertainties are estimated.
Mitotic catastrophe and cell death induced by depletion of centrosomal proteins
Kimura, M; Yoshioka, T; Saio, M; Banno, Y; Nagaoka, H; Okano, Y
Mitotic catastrophe, which refers to cell death or its prologue triggered by aberrant mitosis, can be induced by a heterogeneous group of stimuli, including chromosome damage or perturbation of the mitotic apparatus. We investigated the mechanism of mitotic catastrophe and cell death induced by depletion of centrosomal proteins that perturbs microtubule organization. We transfected cells harboring wild-type or mutated p53 with siRNAs targeting Aurora A, ninein, TOG, TACC3, γ-tubulin, or pericentriolar material-1, and monitored the effects on cell death. Knockdown of Aurora A, ninein, TOG, and TACC3 led to cell death, regardless of p53 status. Knockdown of Aurora A, ninein, and TOG, led to aberrant spindle formation and subsequent cell death, which was accompanied by several features of apoptosis, including nuclear condensation and Annexin V binding in HeLa cells. During this process, cleavage of poly(ADP-ribose) polymerase-1, caspase-3, and caspase-9 was detected, but cleavage of caspase-8 was not. Cell death, monitored by time-lapse imaging, occurred during both interphase and M phase. In cells depleted of a centrosomal protein (Aurora A, ninein, or TOG), the rate of cell death was higher if the cells were cotransfected with siRNA against BubR1 or Mad2 than if they were transfected with siRNA against Bub1 or a control siRNA. These results suggest that metaphase arrest is necessary for the mitotic catastrophe and cell death caused by depletion of centrosomal proteins. Knockdown of centrosomal proteins led to increased phosphorylation of Chk2. Enhanced p-Chk2 localization was also observed at the centrosome in cells arrested in M phase, as well as in the nuclei of dying cells. Cotransfection of siRNAs against Chk2, in combination with depletion of a centrosomal protein, decreased the amount of cell death. Thus, Chk2 activity is indispensable for apoptosis after mitotic catastrophe induced by depletion of centrosomal proteins that perturbs microtubule organization
Development of a virtual probe tip with an application to high aspect ratio microscale features
Bauza, Marcin B.; Hocken, Robert J.; Smith, Stuart T.; Woody, Shane C.
Nondestructive measurement of microscale features remains a challenging metrology problem. For example, to assess a high aspect ratio small hole it is currently common to cut a cross section and measure the features of interest using an atomic force microscope, scanning probe microscope, or scanning electron microscope. Typically, these metrology tools may be suitable for surface finish measurement but often lack the capability for dimensional metrology. The aim of this article is to discuss the development of a high aspect-ratio microscale probe for measurement of microscale features. A 700:1 high aspect ratio probe shank is fabricated with a 7 {mu}m diameter, and attached at one end to an oscillator. The oscillator produces a standing wave in the oscillating probe shank as opposed to conventional probes that use a microscale sphere on the end of a comparatively rigid shank. As a result of the standing wave formed in steady state vibration, the free end of the shank generates an amplitude of oscillation greater than the probe shank diameter. Thus, the probe does not require a spherical ball to serve as the contact point and simply uses the contact diameter of the free end of the vibrating shank. This methodology is referred to as a virtual probe tip. The virtual probe tip in conjunction with a nanopositioning scanner is used to measure surface profile measurements over traverse lengths of 130 {mu}m. In this article, results from profiles of a 500 nm step height and a ruby sphere of diameter 1 mm are presented. Experiments in this article indicate the ability to repeatedly resolve surface features of less than 5 nm while maintaining bandwidths greater than 1 kHz. Furthermore, adhesion problems often encountered with micrometer scaled probes were not observed during profile measurements with this virtual probe.
A dynamic mode of mitotic bookmarking by transcription factors
Teves, Sheila S; An, Luye; Hansen, Anders S; Xie, Liangqi; Darzacq, Xavier; Tjian, Robert
During mitosis, transcription is shut off, chromatin condenses, and most transcription factors (TFs) are reported to be excluded from chromosomes. How do daughter cells re-establish the original transcription program? Recent discoveries that a select set of TFs remain bound on mitotic chromosomes suggest a potential mechanism for maintaining transcriptional programs through the cell cycle termed mitotic bookmarking. Here we report instead that many TFs remain associated with chromosomes in mouse embryonic stem cells, and that the exclusion previously described is largely a fixation artifact. In particular, most TFs we tested are significantly enriched on mitotic chromosomes. Studies with Sox2 reveal that this mitotic interaction is more dynamic than in interphase and is facilitated by both DNA binding and nuclear import. Furthermore, this dynamic mode results from lack of transcriptional activation rather than decreased accessibility of underlying DNA sequences in mitosis. The nature of the cross-linking artifact prompts careful re-examination of the role of TFs in mitotic bookmarking. DOI: http://dx.doi.org/10.7554/eLife.22280.001 PMID:27855781
A Brief History of Research on Mitotic Mechanisms
McIntosh, J. Richard; Hays, Thomas
This chapter describes in summary form some of the most important research on chromosome segregation, from the discovery and naming of mitosis in the nineteenth century until around 1990. It gives both historical and scientific background for the nine chapters that follow, each of which provides an up-to-date review of a specific aspect of mitotic mechanism. Here, we trace the fruits of each new technology that allowed a deeper understanding of mitosis and its underlying mechanisms. We describe how light microscopy, including phase, polarization, and fluorescence optics, provided descriptive information about mitotic events and also enabled important experimentation on mitotic functions, such as the dynamics of spindle fibers and the forces generated for chromosome movement. We describe studies by electron microscopy, including quantitative work with serial section reconstructions. We review early results from spindle biochemistry and genetics, coupled to molecular biology, as these methods allowed scholars to identify key molecular components of mitotic mechanisms. We also review hypotheses about mitotic mechanisms whose testing led to a deeper understanding of this fundamental biological event. Our goal is to provide modern scientists with an appreciation of the work that has laid the foundations for their current work and interests. PMID:28009830
Mechanical control of mitotic progression in single animal cells.
Cattin, Cedric J; Düggelin, Marcel; Martinez-Martin, David; Gerber, Christoph; Müller, Daniel J; Stewart, Martin P
Despite the importance of mitotic cell rounding in tissue development and cell proliferation, there remains a paucity of approaches to investigate the mechanical robustness of cell rounding. Here we introduce ion beam-sculpted microcantilevers that enable precise force-feedback-controlled confinement of single cells while characterizing their progression through mitosis. We identify three force regimes according to the cell response: small forces (∼5 nN) that accelerate mitotic progression, intermediate forces where cells resist confinement (50-100 nN), and yield forces (>100 nN) where a significant decline in cell height impinges on microtubule spindle function, thereby inhibiting mitotic progression. Yield forces are coincident with a nonlinear drop in cell height potentiated by persistent blebbing and loss of cortical F-actin homogeneity. Our results suggest that a buildup of actomyosin-dependent cortical tension and intracellular pressure precedes mechanical failure, or herniation, of the cell cortex at the yield force. Thus, we reveal how the mechanical properties of mitotic cells and their response to external forces are linked to mitotic progression under conditions of mechanical confinement.
Mitotic Chromosome Loss in a Disomic Haploid of SACCHAROMYCES CEREVISIAE
Campbell, D. A.; Fogel, S.; Lusnak, K.
Experiments designed to characterize the incidence of mitotic chromosome loss in a yeast disomic haploid were performed. The selective methods employed utilize the non-mating property of strains disomic for linkage group III and heterozygous at the mating type locus. The principal findings are: (1) The frequency of spontaneous chromosome loss in the disome is of the order 10-4 per cell; this value approximates the frequency in the same population of spontaneous mitotic exchange resulting in homozygosity at the mating type locus. (2) The recovered diploids are pure clones, and thus represent unique events in the disomic haploid. (3) Of the euploid chromosomes recovered after events leading to chromosome loss, approximately 90% retain the parental marker configuration expected from segregation alone; however, the remainder are recombinant for marker genes, and are the result of mitotic exchanges in the disome, especially in regions near the centromere. The recombinant proportion significantly exceeds that expected if chromosome loss and mitotic exchange in the disome were independent events. The data are consistent with a model proposing mitotic nondisjunction as the event responsible for chromosome loss in the disomic haploid. PMID:1092597
High-resolution digital elevation models of the Flade Iceblink feature in NE Greenland
NASA Astrophysics Data System (ADS)
Willis, M. J.; Juntunen, T.; Porter, C. C.; Morin, P. J.
We produce a time series of high-resolution digital elevation models (DEM) to examine the recent evolution of an 8.7 km2 sub-glacial lake collapse feature near the southern summit of the 8500 km2 Flade Isblink Ice Cap (FIIC) in northeastern Greenland [Figure 1]. Visible imagery from the MODerate-resolution Imaging Spectroradiometer (MODIS) indicates the collapse occurred between August 16th and September 6th, 2011 at the site of a recurring moulin. DEMs are extracted using the NASA Ames Stereo Pipeline for the period between June 2012 and late 2013 from 0.5 m resolution along-track stereo image pairs available via the NGA commercial imagery program. The DEMs are compared to a 1996 ERS InSAR derived DEM [Palmer et al., 2010], and to a contemporary airborne laser altimeter swath flown by NASA Icebridge in mid-April 2013 to derive the volume of the feature and the uncertainties on the high-resolution DEMs. The 'mitten' shaped feature is bounded by crevasses on three sides, with a shallow ramp to the south. It is ~70 m deep, 3.7 km north-to-south and 3 km east-to-west and has a volume of ~0.3 km3. Ice penetrating radar from a nearby Icebridge mission in May 2011, indicates the ice is approximately 550 m thick and that the bed is very flat and smooth about 1 km to the southeast of the feature. The nearby bed topography, local geology and lack of recorded seismicity in the area indicate it is unlikely that the feature is the result of either subglacial volcanic activity or the collapse of a limestone karst feature below the ice cap - the neighboring Princess Elizabeth Alps are composed of 420 Ma Caledonide fold belt gneisses. The presence of recurring supraglacial meltwater streams and drainage into the feature, its rapid formation and its steep sided nature instead suggest that it formed during the rapid drainage of a sub-glacial lake - which is, as far as we are aware, the first recorded instance of such an occurrence in Greenland. Meltwater observed using 250 m
Centrin: Another target of monastrol, an inhibitor of mitotic spindle
NASA Astrophysics Data System (ADS)
Duan, Lian; Wang, Tong-Qing; Bian, Wei; Liu, Wen; Sun, Yue; Yang, Bin-Sheng
Monastrol, a cell-permeable inhibitor, considered to specifically inhibit kinesin Eg5, can cause mitotic arrest and monopolar spindle formation, thus exhibiting antitumor properties. Centrin, a ubiquitous protein associated with centrosome, plays a critical role in centrosome duplication. Moreover, a correlation between centrosome amplification and cancer has been reported. In this study, it is proposed for the first time that centrin may be another target of the anticancer drug monastrol since monastrol can effectively inhibit not only the growth of the transformed Escherichia coli cells in vivo, but also the Lu3+-dependent self-assembly of EoCen in vitro. The two closely related compounds (Compounds 1 and 2) could not take the same effect. Fluorescence titration experiments suggest that four monastrols per protein is the optimum binding pattern, and the binding constants at different temperatures were obtained. Detailed thermodynamic analysis indicates that hydrophobic force is the main acting force between monastrol and centrin, and the extent of monastrol inhibition of centrin self-assembly is highly dependent upon the hydrophobic region of the protein, which is largely exposed by the binding of metal ions.
Centrophilin: a novel mitotic spindle protein involved in microtubule nucleation
A novel protein has been identified which may serve a key function in nucleating spindle microtubule growth in mitosis. This protein, called centrophilin, is sequentially relocated from the centromeres to the centrosomes to the midbody in a manner dependent on the mitotic phase. Centrophilin was initially detected by immunofluorescence with a monoclonal, primate-specific antibody (2D3) raised against kinetochore- enriched chromosome extract from HeLa cells (Valdivia, M. M., and B. R. Brinkley. 1985. J. Cell Biol. 101:1124-1134). Centrophilin forms prominent crescents at the poles of the metaphase spindle, gradually diminishes during anaphase, and bands the equatorial ends of midbody microtubules in telophase. The formation and breakdown of the spindle and midbody correlates in time and space with the aggregation and disaggregation of centrophilin foci. Immunogold EM reveals that centrophilin is a major component of pericentriolar material in metaphase. During recovery from microtubule inhibition, centrophilin foci act as nucleation sites for the assembly of spindle tubules. The 2D3 probe recognizes two high molecular mass polypeptides, 180 and 210 kD, on immunoblots of whole HeLa cell extract. Taken together, these data and the available literature on microtubule dynamics point inevitably to a singular model for control of spindle tubule turnover. PMID:1991791
Plasma density features associated with strong convection in the winter high-latitude F region
NASA Technical Reports Server (NTRS)
Sojka, J. J.; Raitt, W. J.; Schunk, R. W.
A single plasma convection model was combined with an ionospheric-atmospheric composition model to study plasma density features associated with string convection in the winter high-latitude F region. Time dependent, three-dimensional, ion density distributions for NO(+), O2(+), N2(+), O(+) and He(+) were produced, and the ionosphere above 42 deg N magnetic latitude was covered for 24 hours. The study found that for strong and weak convection, electron density exhibited a variation with altitude, latitude, longitude and universal time. Ionospheric features were evident for strong convection, but modified in comparison with those found for slow convection. Also found for strong convection was a more pronounced tongue of ionization, the appearance of a new polar hole in the polar cap, and a midlatitude electron density trough that was not as deep as found for a weak convection. In addition, good agreement was found between predictions and Atmosphere Explorer measurements of ion composition variation with latitude and local time.
Roles of different pools of the mitotic checkpoint complex and the mechanisms of their disassembly
Eytan, Esther; Sitry-Shevah, Danielle; Teichner, Adar; Hershko, Avram
The mitotic (or spindle assembly) checkpoint system prevents premature separation of sister chromatids in mitosis. When the checkpoint is turned on, the mitotic checkpoint complex (MCC) inhibits the ubiquitin ligase anaphase-promoting complex/cyclosome (APC/C). MCC is composed of the checkpoint proteins BubR1, Bub3, and Mad2 associated with the APC/C activator Cdc20. The mechanisms of the assembly of MCC when the checkpoint is turned on, and of its disassembly when the checkpoint is inactivated, are not sufficiently understood. Previous reports indicated that APC/C-mediated polyubiquitylation of Cdc20 in MCC is required for the dissociation of APC/C-associated MCC, but not of free MCC. The pool of free MCC is disassembled by an ATP-dependent process stimulated by the Mad2-binding protein p31comet. It remained unknown whether free MCC is the precursor or the dissociation product of APC/C-bound MCC. By characterizing the mechanisms of the disassembly of APC/C-bound MCC in a purified system, we find that it cannot be the source of free MCC, because it is bound at high affinity and is released only in ubiquitylated or partially disassembled forms. By the use of a cell-free system from Xenopus eggs that reproduces the mitotic checkpoint, we show that MCC can be assembled in the absence of APC/C in a checkpoint-dependent manner. We propose that when the checkpoint is turned on, free MCC is the precursor of APC/C-bound MCC. When the mitotic checkpoint is extinguished, both APC/C-bound and free MCC pools have to be disassembled to release APC/C from inhibition. PMID:23754430
p21-activated kinase 4 regulates mitotic spindle positioning and orientation.
Bompard, Guillaume; Morin, Nathalie
During mitosis, microtubules (MTs) are massively rearranged into three sets of highly dynamic MTs that are nucleated from the centrosomes to form the mitotic spindle. Tight regulation of spindle positioning in the dividing cell and chromosome alignment at the center of the metaphase spindle are required to ensure perfect chromosome segregation and to position the cytokinetic furrow that will specify the two daughter cells. Spindle positioning requires regulation of MT dynamics, involving depolymerase activities together with cortical and kinetochore-mediated pushing and pulling forces acting on astral MTs and kinetochore fibres. These forces rely on MT motor activities. Cortical pulling forces exerted on astral MTs depend upon dynein/dynactin complexes and are essential in both symmetric and asymmetric cell division. A well-established spindle positioning pathway regulating the cortical targeting of dynein/dynactin involves the conserved LGN (Leu-Gly-Asn repeat-enriched-protein) and NuMA (microtubule binding nuclear mitotic apparatus protein) complex. Spindle orientation is also regulated by integrin-mediated cell adhesion and actin retraction fibres that respond to mechanical stress and are influenced by the microenvironment of the dividing cell. Altering the capture of astral MTs or modulating pulling forces affects spindle position, which can impair cell division, differentiation and embryogenesis. In this general scheme, the activity of mitotic kinases such as Auroras and Plk1 (Polo-like kinase 1) is crucial. Recently, the p21-activated kinases (PAKs) emerged as novel important players in mitotic progression. In our recent article, we demonstrated that PAK4 regulates spindle positioning in symmetric cell division. In this commentary, and in light of recent published studies, we discuss how PAK4 could participate in the regulation of mechanisms involved in spindle positioning and orientation.
Twinning and mitotic crossing-over: some possibilities and their implications.
Côté, G B; Gyftodimou, J
Mitotic crossing-over does occur in man and is much more frequent and important than generally assumed. Its postzygotic occurrence before an embryo differentiates into MZ twins is theoretically predicted to have disrupting effects on genomic imprinting and cis-acting sequences, with consequences ranging from early lethality to MZ twin discordance. Some predictions are at odds with classical views on twinning and include a high discordance rate of MZ twins for some genetic diseases. A review of MZ twin discordance and an attempt at explaining some of the data lead one to hypothesize both the existence of a sex differences in the rate of mitotic crossing-over and the impossibility for crossed X chromosomes to undergo inactivation. The close interrelationship of twinning and midline malformations further suggests a major role of mitotic crossing-over in the induction of the twinning process itself. The model can be tested with molecular methods and provides a new approach for the gene mapping of so-called multifactorial diseases and of rarer disorders with apparently irregular inheritance. PMID:2063864
Cytoplasmic flows as signatures for the mechanics of mitotic spindle positioning
NASA Astrophysics Data System (ADS)
Nazockdast, Ehssan; Rahimian, Abtin; Needleman, Daniel; Shelley, Michael
The proper positioning of the mitotic spindle is crucial for asymmetric cell division and generating cell diversity during development. We use dynamic simulations to study the cytoplasmic flows generated by three possible active forcing mechanisms involved in positioning of the mitotic spindle in the first cell division of C.elegans embryo namely cortical pulling, cortical pushing, and cytoplasmic pulling mechanisms. The numerical platform we have developed for simulating cytoskeletal assemblies is the first to incorporate the interactions between the fibers and other intracellular bodies with the cytoplasmic fluid, while also accounting for their polymerization, and interactions with motor proteins. The hydrodynamic interactions are computed using boundary integral methods in Stokes flow coupled with highly efficient fast summation techniques that reduce the computational cost to scale linearly with the number of fibers and other bodies. We show that although all three force transduction mechanisms predict proper positioning and orientation of the mitotic spindle, each model produces a different signature in its induced cytoplasmic flow and MT conformation. We suggest that cytoplasmic flows and MT conformation can be used to differentiate between these mechanisms.
Disruption of IFT complex A causes cystic kidneys without mitotic spindle misorientation.
Jonassen, Julie A; SanAgustin, Jovenal; Baker, Stephen P; Pazour, Gregory J
Intraflagellar transport (IFT) complexes A and B build and maintain primary cilia. In the mouse, kidney-specific or hypomorphic mutant alleles of IFT complex B genes cause polycystic kidneys, but the influence of IFT complex A proteins on renal development is not well understood. In the present study, we found that HoxB7-Cre-driven deletion of the complex A gene Ift140 from collecting ducts disrupted, but did not completely prevent, cilia assembly. Mutant kidneys developed collecting duct cysts by postnatal day 5, with rapid cystic expansion and renal dysfunction by day 15 and little remaining parenchymal tissue by day 20. In contrast to many models of polycystic kidney disease, precystic Ift140-deleted collecting ducts showed normal centrosomal positioning and no misorientation of the mitotic spindle axis, suggesting that disruption of oriented cell division is not a prerequisite to cyst formation in these kidneys. Precystic collecting ducts had an increased mitotic index, suggesting that cell proliferation may drive cyst expansion even with normal orientation of the mitotic spindle. In addition, we observed significant increases in expression of canonical Wnt pathway genes and mediators of Hedgehog and tissue fibrosis in highly cystic, but not precystic, kidneys. Taken together, these studies indicate that loss of Ift140 causes pronounced renal cystic disease and suggest that abnormalities in several different pathways may influence cyst progression.
Computational analysis of the spatial distribution of mitotic spindle angles in mouse developing airway
NASA Astrophysics Data System (ADS)
Tang, Nan; Marshall, Wallace F.
Investigating the spatial information of cellular processes in tissues during mouse embryo development is one of the major technical challenges in development biology. Many imaging methods are still limited to the volumes of tissue due to tissue opacity, light scattering and the availability of advanced imaging tools. For analyzing the mitotic spindle angle distribution in developing mouse airway epithelium, we determined spindle angles in mitotic epithelial cells on serial sections of whole airway of mouse embryonic lungs. We then developed a computational image analysis to obtain spindle angle distribution in three dimensional airway reconstructed from the data obtained from all serial sections. From this study, we were able to understand how mitotic spindle angles are distributed in a whole airway tube. This analysis provides a potentially fast, simple and inexpensive alternative method to quantitatively analyze cellular process at subcellular resolution. Furthermore, this analysis is not limited to the size of tissues, which allows to obtain three dimensional and high resolution information of cellular processes in cell populations deeper inside intact organs.
Insulin growth factors regulate the mitotic cycle in cultured rat sympathetic neuroblasts
DiCicco-Bloom, E.; Black, I.B. )
While neuronal mitosis is uniquely restricted to early development, the underlying regulation remains to be defined. The authors have now developed a dissociated, embryonic sympathetic neuron culture system that uses fully defined medium in which cells enter the mitotic cycle. The cultured cells expressed two neuronal traits, tyrosine hydroxylase and the neuron-specific 160-kDa neurofilament subunit protein, but were devoid of glial fibrillary acidic protein, a marker for non-myelin-forming Schwann cells in ganglia. Approximately one-third of the tyrosine hydroxylase-positive cells synthesized DNA in culture, specifically incorporating ({sup 3}H)thymidine into their nuclei. They used this system to define factors regulating the mitotic cycle in sympathetic neuroblasts. Members of the insulin family of growth factors, including insulin and insulin-like growth factors I and II, regulated DNA synthesis in the presumptive neuroblasts. Insulin more than doubled the proportion of tyrosine hydroxylase-positive cells entering the mitotic cycle, as indicated by autoradiography of ({sup 3}H)thymidine incorporation into nuclei. Scintillation spectrometry was an even more sensitive index of DNA synthesis. In contrast, the trophic protein nerve growth factor exhibited no mitogenic effect, suggesting that the mitogenic action of insulin growth factors is highly specific. The observations are discussed in the context of the detection of insulin growth factors and receptors in the developing brain.
The novel combination of chlorpromazine and pentamidine exerts synergistic antiproliferative effects through dual mitotic action.
Lee, Margaret S; Johansen, Lisa; Zhang, Yanzhen; Wilson, Amy; Keegan, Mitchell; Avery, William; Elliott, Peter; Borisy, Alexis A; Keith, Curtis T
Combination therapy has proven successful in treating a wide variety of aggressive human cancers. Historically, combination treatments have been discovered through serendipity or lengthy trials using known anticancer agents with similar indications. We have used combination high-throughput screening to discover the unexpected synergistic combination of an antiparasitic agent, pentamidine, and a phenothiazine antipsychotic, chlorpromazine. This combination, CRx-026, inhibits the growth of tumor cell lines in vivo more effectively than either pentamidine or chlorpromazine alone. Here, we report that CRx-026 exerts its antiproliferative effect through synergistic dual mitotic action. Chlorpromazine is a potent and specific inhibitor of the mitotic kinesin KSP/Eg5 and inhibits tumor cell proliferation through mitotic arrest and accumulation of monopolar spindles. Pentamidine treatment results in chromosomal segregation defects and delayed progression through mitosis, consistent with inhibition of the phosphatase of regenerating liver family of phosphatases. We also show that CRx-026 synergizes in vitro and in vivo with the microtubule-binding agents paclitaxel and vinorelbine. These data support a model where dual action of pentamidine and chlorpromazine in mitosis results in synergistic antitumor effects and show the importance of systematic screening for combinations of targeted agents.
Functional connectivity classification of autism identifies highly predictive brain features but falls short of biomarker standards
Plitt, Mark; Barnes, Kelly Anne; Martin, Alex
Objectives Autism spectrum disorders (ASD) are diagnosed based on early-manifesting clinical symptoms, including markedly impaired social communication. We assessed the viability of resting-state functional MRI (rs-fMRI) connectivity measures as diagnostic biomarkers for ASD and investigated which connectivity features are predictive of a diagnosis. Methods Rs-fMRI scans from 59 high functioning males with ASD and 59 age- and IQ-matched typically developing (TD) males were used to build a series of machine learning classifiers. Classification features were obtained using 3 sets of brain regions. Another set of classifiers was built from participants' scores on behavioral metrics. An additional age and IQ-matched cohort of 178 individuals (89 ASD; 89 TD) from the Autism Brain Imaging Data Exchange (ABIDE) open-access dataset (http://fcon_1000.projects.nitrc.org/indi/abide/) were included for replication. Results High classification accuracy was achieved through several rs-fMRI methods (peak accuracy 76.67%). However, classification via behavioral measures consistently surpassed rs-fMRI classifiers (peak accuracy 95.19%). The class probability estimates, P(ASD|fMRI data), from brain-based classifiers significantly correlated with scores on a measure of social functioning, the Social Responsiveness Scale (SRS), as did the most informative features from 2 of the 3 sets of brain-based features. The most informative connections predominantly originated from regions strongly associated with social functioning. Conclusions While individuals can be classified as having ASD with statistically significant accuracy from their rs-fMRI scans alone, this method falls short of biomarker standards. Classification methods provided further evidence that ASD functional connectivity is characterized by dysfunction of large-scale functional networks, particularly those involved in social information processing. PMID:25685703
Simulation of compact circumstellar shells around Type Ia supernovae and the resulting high-velocity features
NASA Astrophysics Data System (ADS)
Mulligan, Brian W.; Wheeler, J. Craig
For Type Ia supernovae that are observed prior to B-band maximum (approximately 18-20 days after the explosion) Ca absorption features are observed at velocities of order 10,000 km/s faster than the typical photospheric features. These high velocity features weaken in the first couple of weeks, disappearing entirely by a week after B-band maximum. The source of this high velocity material is uncertain: it may be the result of interaction between the supernova and circumstellar material or may be the result of plumes or bullets of material ejected during the course of the explosion. We simulate interaction between a supernova and several compact circumstellar shells, located within 0.03 solar radii of the progenitor white dwarf and having masses of 0.02 solar masses or less. We use FLASH to perform hydrodynamic simulations of the system to determine the structure of the ejecta and shell components after the interaction, then use these results to generate synthetic spectra with 1 day cadence for the first 25 days after the explosion. We compare the evolution of the velocity and pseudo-equivalent width of the Ca near-infrared triplet features in the synthetic spectra to observed values, demonstrating that these models are consistent with observations. Additionally, we fit the observed spectra of SN 2011fe (Parrent 2012, Pereira 2013) prior to B-band maximum using these models and synthetic spectra and provide an estimate for Ca abundance within the circumstellar material with implications for the mechanism by which the white dwarf explodes.
Adjuvant Radiation Therapy Alone for HPV Related Oropharyngeal Cancers with High Risk Features
Su, William; Liu, Jerry; Miles, Brett A.; Genden, Eric M.; Misiukiewicz, Krzysztof J.; Posner, Marshall; Gupta, Vishal; Bakst, Richard L.
Background Current standard of care for oropharyngeal cancers with positive surgical margins and/or extracapsular extension is adjuvant chemoradiotherapy. It is unknown whether HPV+ oropharyngeal cancer benefits from this treatment intensification. Objective To investigate the outcomes of HPV+ patients treated with adjuvant radiotherapy alone when chemoradiotherapy was indicated based on high risk pathological features. They were compared with high risk HPV+ patients treated with adjuvant chemoradiotherapy. Methods All high risk HPV+ oropharyngeal cancer patients (9) who received radiotherapy alone were identified. We also identified 17 patients who received chemoradiotherapy as a comparison group. Median follow up time was 37.3 months. Results No local failures developed in adjuvant radiotherapy group. There was 1 distant recurrence in this cohort and 3 in CRT cohort. Regarding toxicity, 8 (47.1%) chemoradiotherapy patients had >10 lb. weight loss (p = 0.013), despite 75% of them having a percutaneous endoscopic gastrostomy tube placed. No individuals in radiotherapy group experienced a >10 lb. weight loss and none required a gastrostomy tube. Conclusions This series provides preliminary evidence suggesting that the omission of concurrent chemotherapy to adjuvant radiotherapy may offer comparative local control rates with a lower toxicity profile in the setting of HPV+ patients with traditional high risk features. PMID:27930732
Automated Identification of River Hydromorphological Features Using UAV High Resolution Aerial Imagery
Rivas Casado, Monica; Ballesteros Gonzalez, Rocio; Kriechbaumer, Thomas; Veal, Amanda
European legislation is driving the development of methods for river ecosystem protection in light of concerns over water quality and ecology. Key to their success is the accurate and rapid characterisation of physical features (i.e., hydromorphology) along the river. Image pattern recognition techniques have been successfully used for this purpose. The reliability of the methodology depends on both the quality of the aerial imagery and the pattern recognition technique used. Recent studies have proved the potential of Unmanned Aerial Vehicles (UAVs) to increase the quality of the imagery by capturing high resolution photography. Similarly, Artificial Neural Networks (ANN) have been shown to be a high precision tool for automated recognition of environmental patterns. This paper presents a UAV based framework for the identification of hydromorphological features from high resolution RGB aerial imagery using a novel classification technique based on ANNs. The framework is developed for a 1.4 km river reach along the river Dee in Wales, United Kingdom. For this purpose, a Falcon 8 octocopter was used to gather 2.5 cm resolution imagery. The results show that the accuracy of the framework is above 81%, performing particularly well at recognising vegetation. These results leverage the use of UAVs for environmental policy implementation and demonstrate the potential of ANNs and RGB imagery for high precision river monitoring and river management. PMID:26556355
Automated Identification of River Hydromorphological Features Using UAV High Resolution Aerial Imagery.
Casado, Monica Rivas; Gonzalez, Rocio Ballesteros; Kriechbaumer, Thomas; Veal, Amanda
European legislation is driving the development of methods for river ecosystem protection in light of concerns over water quality and ecology. Key to their success is the accurate and rapid characterisation of physical features (i.e., hydromorphology) along the river. Image pattern recognition techniques have been successfully used for this purpose. The reliability of the methodology depends on both the quality of the aerial imagery and the pattern recognition technique used. Recent studies have proved the potential of Unmanned Aerial Vehicles (UAVs) to increase the quality of the imagery by capturing high resolution photography. Similarly, Artificial Neural Networks (ANN) have been shown to be a high precision tool for automated recognition of environmental patterns. This paper presents a UAV based framework for the identification of hydromorphological features from high resolution RGB aerial imagery using a novel classification technique based on ANNs. The framework is developed for a 1.4 km river reach along the river Dee in Wales, United Kingdom. For this purpose, a Falcon 8 octocopter was used to gather 2.5 cm resolution imagery. The results show that the accuracy of the framework is above 81%, performing particularly well at recognising vegetation. These results leverage the use of UAVs for environmental policy implementation and demonstrate the potential of ANNs and RGB imagery for high precision river monitoring and river management.
Shaping mitotic chromosomes: From classical concepts to molecular mechanisms
Kschonsak, Marc; Haering, Christian H
How eukaryotic genomes are packaged into compact cylindrical chromosomes in preparation for cell divisions has remained one of the major unsolved questions of cell biology. Novel approaches to study the topology of DNA helices inside the nuclei of intact cells, paired with computational modeling and precise biomechanical measurements of isolated chromosomes, have advanced our understanding of mitotic chromosome architecture. In this Review Essay, we discuss – in light of these recent insights – the role of chromatin architecture and the functions and possible mechanisms of SMC protein complexes and other molecular machines in the formation of mitotic chromosomes. Based on the information available, we propose a stepwise model of mitotic chromosome condensation that envisions the sequential generation of intra-chromosomal linkages by condensin complexes in the context of cohesin-mediated inter-chromosomal linkages, assisted by topoisomerase II. The described scenario results in rod-shaped metaphase chromosomes ready for their segregation to the cell poles. PMID:25988527
Shaping mitotic chromosomes: From classical concepts to molecular mechanisms.
Kschonsak, Marc; Haering, Christian H
How eukaryotic genomes are packaged into compact cylindrical chromosomes in preparation for cell divisions has remained one of the major unsolved questions of cell biology. Novel approaches to study the topology of DNA helices inside the nuclei of intact cells, paired with computational modeling and precise biomechanical measurements of isolated chromosomes, have advanced our understanding of mitotic chromosome architecture. In this Review Essay, we discuss - in light of these recent insights - the role of chromatin architecture and the functions and possible mechanisms of SMC protein complexes and other molecular machines in the formation of mitotic chromosomes. Based on the information available, we propose a stepwise model of mitotic chromosome condensation that envisions the sequential generation of intra-chromosomal linkages by condensin complexes in the context of cohesin-mediated inter-chromosomal linkages, assisted by topoisomerase II. The described scenario results in rod-shaped metaphase chromosomes ready for their segregation to the cell poles.
Rohitukine inhibits in vitro adipogenesis arresting mitotic clonal expansion and improves dyslipidemia in vivo[S
Varshney, Salil; Shankar, Kripa; Beg, Muheeb; Balaramnavar, Vishal M.; Mishra, Sunil Kumar; Jagdale, Pankaj; Srivastava, Shishir; Chhonker, Yashpal S.; Lakshmi, Vijai; Chaudhari, Bhushan P.; Bhatta, Rabi Shankar; Saxena, Anil Kumar; Gaikwad, Anil Nilkanth
We developed a common feature pharmacophore model using known antiadipogenic compounds (CFPMA). We identified rohitukine, a reported chromone anticancer alkaloid as a potential hit through in silico mapping of the in-house natural product library on CFPMA. Studies were designed to assess the antiadipogenic potential of rohitukine. Rohitukine was isolated from Dysoxylum binacteriferum Hook. to ⬧95% purity. As predicted by CFPMA, rohitukine was indeed found to be an antiadipogenic molecule. Rohitukine inhibited lipid accumulation and adipogenic differentiation in a concentration- and exposure-time-dependent manner in 3T3-L1 and C3H10T1/2 cells. Rohitukine downregulated expression of PPARγ, CCAAT/enhancer binding protein α, adipocyte protein 2 (aP2), FAS, and glucose transporter 4. It also suppressed mRNA expression of LPL, sterol-regulatory element binding protein (SREBP) 1c, FAS, and aP2, the downstream targets of PPARγ. Rohitukine arrests cells in S phase during mitotic clonal expansion. Rohitukine was bioavailable, and 25.7% of orally administered compound reached systemic circulation. We evaluated the effect of rohitukine on dyslipidemia induced by high-fat diet in the hamster model. Rohitukine increased hepatic expression of liver X receptor α and decreased expression of SREBP-2 and associated targets. Rohitukine decreased hepatic and gonadal lipid accumulation and ameliorated dyslipidemia significantly. In summary, our strategy to identify a novel antiadipogenic molecule using CFPMA successfully resulted in identification of rohitukine, which confirmed antiadipogenic activity and also exhibited in vivo antidyslipidemic activity. PMID:24646949
Cell death by mitotic catastrophe: a molecular definition.
Castedo, Maria; Perfettini, Jean-Luc; Roumier, Thomas; Andreau, Karine; Medema, Rene; Kroemer, Guido
The current literature is devoid of a clearcut definition of mitotic catastrophe, a type of cell death that occurs during mitosis. Here, we propose that mitotic catastrophe results from a combination of deficient cell-cycle checkpoints (in particular the DNA structure checkpoints and the spindle assembly checkpoint) and cellular damage. Failure to arrest the cell cycle before or at mitosis triggers an attempt of aberrant chromosome segregation, which culminates in the activation of the apoptotic default pathway and cellular demise. Cell death occurring during the metaphase/anaphase transition is characterized by the activation of caspase-2 (which can be activated in response to DNA damage) and/or mitochondrial membrane permeabilization with the release of cell death effectors such as apoptosis-inducing factor and the caspase-9 and-3 activator cytochrome c. Although the morphological aspect of apoptosis may be incomplete, these alterations constitute the biochemical hallmarks of apoptosis. Cells that fail to execute an apoptotic program in response to mitotic failure are likely to divide asymmetrically in the next round of cell division, with the consequent generation of aneuploid cells. This implies that disabling of the apoptotic program may actually favor chromosomal instability, through the suppression of mitotic catastrophe. Mitotic catastrophe thus may be conceived as a molecular device that prevents aneuploidization, which may participate in oncogenesis. Mitotic catastrophe is controlled by numerous molecular players, in particular, cell-cycle-specific kinases (such as the cyclin B1-dependent kinase Cdk1, polo-like kinases and Aurora kinases), cell-cycle checkpoint proteins, survivin, p53, caspases and members of the Bcl-2 family.
Fully functional global genome repair of (6-4) photoproducts and compromised transcription-coupled repair of cyclobutane pyrimidine dimers in condensed mitotic chromatin.
Komura, Jun-ichiro; Ikehata, Hironobu; Mori, Toshio; Ono, Tetsuya
During mitosis, chromatin is highly condensed, and activities such as transcription and semiconservative replication do not occur. Consequently, the condensed condition of mitotic chromatin is assumed to inhibit DNA metabolism by impeding the access of DNA-transacting proteins. However, about 40 years ago, several researchers observed unscheduled DNA synthesis in UV-irradiated mitotic chromosomes, suggesting the presence of excision repair. We re-examined this subject by directly measuring the removal of UV-induced DNA lesions by an ELISA and by a Southern-based technique in HeLa cells arrested at mitosis. We observed that the removal of (6-4) photoproducts from the overall genome in mitotic cells was as efficient as in interphase cells. This suggests that global genome repair of (6-4) photoproducts is fully functional during mitosis, and that the DNA in mitotic chromatin is accessible to proteins involved in this mode of DNA repair. Nevertheless, not all modes of DNA repair seem fully functional during mitosis. We also observed that the removal of cyclobutane pyrimidine dimers from the dihydrofolate reductase and c-MYC genes in mitotic cells was very slow. This suggests that transcription-coupled repair of cyclobutane pyrimidine dimers is compromised or non-functional during mitosis, which is probably the consequence of mitotic transcriptional repression.
High-speed video imaging and digital analysis of microscopic features in contracting striated muscle cells
NASA Astrophysics Data System (ADS)
Roos, Kenneth P.; Taylor, Stuart R.
The rapid motion of microscopic features such as the cross striations of single contracting muscle cells are difficult to capture with conventional optical microscopes, video systems, and image processing approaches. An integrated digital video imaging microscope system specifically designed to capture images from single contracting muscle cells at speeds of up to 240 Hz and to analyze images to extract features critical for the understanding of muscle contraction is described. This system consists of a brightfield microscope with immersion optics coupled to a high-speed charge-coupled device (CCD) video camera, super-VHS (S- VHS) and optical media disk video recording (OMDR) systems, and a semiautomated digital image analysis system. Components are modified to optimize spatial and temporal resolution to permit the evaluation of submicrometer features in real physiological time. This approach permits the critical evaluation of the magnitude, time course, and uniformity of contractile function throughout the volume of a single living cell with higher temporal and spatial resolutions than previously possible.
Classification of high resolution imagery based on fusion of multiscale texture features
NASA Astrophysics Data System (ADS)
Liu, Jinxiu; Liu, Huiping; Lv, Ying; Xue, Xiaojuan
In high resolution data classification process, combining texture features with spectral bands can effectively improve the classification accuracy. However, the window size which is difficult to choose is regarded as an important factor influencing overall classification accuracy in textural classification and current approaches to image texture analysis only depend on a single moving window which ignores different scale features of various land cover types. In this paper, we propose a new method based on the fusion of multiscale texture features to overcome these problems. The main steps in new method include the classification of fixed window size spectral/textural images from 3×3 to 15×15 and comparison of all the posterior possibility values for every pixel, as a result the biggest probability value is given to the pixel and the pixel belongs to a certain land cover type automatically. The proposed approach is tested on University of Pavia ROSIS data. The results indicate that the new method improve the classification accuracy compared to results of methods based on fixed window size textural classification.
Plasma etching of high-resolution features in a fullerene molecular resist
NASA Astrophysics Data System (ADS)
Manyam, J.; Manickam, M.; Preece, J. A.; Palmer, R. E.; Robinson, A. P. G.
As resist films become thinner, so as to reduce problems of aspect ratio related pattern collapse at high-resolution, it is becoming increasingly difficult to transfer patterns with useful aspect ratio by directly etching the resist. It has become common to use the photoresist to pattern an intermediate hardmask, which then protects the silicon substrate during etching, allowing useful aspect ratios but adding process complexity. We have previously described a fullerene based electron beam lithography resist capable of 20 nm halfpitch and 12 nm sparse features, at a sensitivity of less than 10 μC/cm2 at 20 keV. The fullerene resist has high etch durability - comparable to that of commercial novolac resists - and has previously demonstrated an etch selectivity of 3:1 to silicon using electron cyclotron resonance microwave plasma etching with SF6. Here a study of the capabilities of this resist when using Inductively Coupled Plasma etching is presented. Line-space patterns with half-pitches in the range 25 nm to 100 nm, together with sparse features (~20 nm linewidth on a 200 nm pitch) were produced in ~30 nm thick resist films using electron beam lithography, and transferred to silicon using an inductively coupled plasma etcher. Several combinations of SF6, CF4, CHF3 and C4F8process gases were explored. Etch selectivity and anisotropy were studied as a range of etching parameters, such as ICP and RF power, gas flow rate, pressure and temperature were varied. Etch selectivities in excess of 9:1 were demonstrated. Techniques for minimizing aspect ratio dependent etching effects in dense features, including the use of ashing or high etching pressures were also examined.
Force and the spindle: Mechanical cues in mitotic spindle orientation
Nestor-Bergmann, Alexander; Goddard, Georgina; Woolner, Sarah
The mechanical environment of a cell has a profound effect on its behaviour, from dictating cell shape to driving the transcription of specific genes. Recent studies have demonstrated that mechanical forces play a key role in orienting the mitotic spindle, and therefore cell division, in both single cells and tissues. Whilst the molecular machinery that mediates the link between external force and the mitotic spindle remains largely unknown, it is becoming increasingly clear that this is a widely used mechanism which could prove vital for coordinating cell division orientation across tissues in a variety of contexts. PMID:25080021
High-throughput screening for thermoelectric sulphides by using crystal structure features as descriptors
NASA Astrophysics Data System (ADS)
Zhang, Ruizhi; Du, Baoli; Chen, Kan; Reece, Mike; Materials Research Insititute Team
With the increasing computational power and reliable databases, high-throughput screening is playing a more and more important role in the search of new thermoelectric materials. Rather than the well established density functional theory (DFT) calculation based methods, we propose an alternative approach to screen for new TE materials: using crystal structural features as 'descriptors'. We show that a non-distorted transition metal sulphide polyhedral network can be a good descriptor for high power factor according to crystal filed theory. By using Cu/S containing compounds as an example, 1600+ Cu/S containing entries in the Inorganic Crystal Structure Database (ICSD) were screened, and of those 84 phases are identified as promising thermoelectric materials. The screening results are validated by both electronic structure calculations and experimental results from the literature. We also fabricated some new compounds to test our screening results. Another advantage of using crystal structure features as descriptors is that we can easily establish structural relationships between the identified phases. Based on this, two material design approaches are discussed: 1) High-pressure synthesis of metastable phase; 2) In-situ 2-phase composites with coherent interface. This work was supported by a Marie Curie International Incoming Fellowship of the European Community Human Potential Program.
High frequency of genetic recombination is a common feature of primate lentivirus replication.
Chen, Jianbo; Powell, Douglas; Hu, Wei-Shau
Recent studies indicate that human immunodeficiency virus type 1 (HIV-1) recombines at exceedingly high rates, approximately 1 order of magnitude more frequently than simple gammaretroviruses such as murine leukemia virus and spleen necrosis virus. We hypothesize that this high frequency of genetic recombination is a common feature of primate lentiviruses. Alternatively, it is possible that HIV-1 is unique among primate lentiviruses in possessing high recombination rates. Among other primate lentiviruses, only the molecular mechanisms of HIV-2 replication have been extensively studied. There are reported differences between the replication mechanisms of HIV-1 and those of HIV-2, such as preferences for RNA packaging in cis and properties of reverse transcriptase and RNase H activities. These biological disparities could lead to differences in recombination rates between the two viruses. Currently, HIV-1 is the only primate lentivirus in which recombination rates have been measured. To test our hypothesis, we established recombination systems to measure the recombination rates of two other primate lentiviruses, HIV-2 and simian immunodeficiency virus from African green monkeys (SIVagm), in one round of viral replication. We determined that, for markers separated by 588, 288, and 90 bp, HIV-2 recombined at rates of 7.4%, 5.5%, and 2.4%, respectively, whereas SIVagm recombined at rates of 7.8%, 5.6%, and 2.7%, respectively. These high recombination rates are within the same range as the previously measured HIV-1 recombination rates. Taken together, our results indicate that HIV-1, HIV-2, and SIVagm all possess high recombination frequencies; hence, the high recombination potential is most likely a common feature of primate lentivirus replication.
Specific features of diffuse photon migration in highly scattering media with optical properties of biological tissues
Proskurin, S G; Potlov, A Yu; Frolov, S V
Specific features of motion of photon density normalised maximum (PDNM) of pulsed radiation in highly scattering media with optical properties of biological tissues are described. A numerical simulation has confirmed that, when the object is a homogeneous cylinder, PDNM always moves to its geometric centre. In the presence of an absorbing inhomogeneity, PDNM moves towards the point symmetric to the geometric centre of the inhomogeneity with respect to the centre of the cylindrical object. In the presence of a scattering inhomogeneity, PDNM moves towards its geometric centre. (radiation scattering)
Characteristic features of topside ionograms in the high-latitude ionosphere.
NASA Astrophysics Data System (ADS)
Panshin, Evgeniy; Danilkin, Nick; Tsybulya, Konstantin; Zhuravliov, Sergey
Topside ionograms display a multitude of specific features in the high-latitude regions. In this report we present an analysis of these features based upon topside ionograms of the Kosmos-1809 satellite taken in May-June 1987. These ionograms were received onboard icebreaker Sibir during a polar expedition in this time. Since the ionograms were downlinked directly in the time of sounding, they were not strongly curtailed to fit the limited onboard memory and thus were much more informative. Acquiring the data in such way allowed us to see little-studied and even unknown ionogram features. Among them we note traces of a characteristic form which were interpreted earlier as signal reflections from almost vertical walls with increased electron density. Such structures are typical for the auroral oval ionosphere. To interpret this features we used a technique of ray trajectory synthesis. We present a sequence of ionograms with all phases of closing to, flying through and away from a higher-density wall. Quite often one find on the polar ionograms broad-band noise signals in different frequency ranges. On the ionograms they are seen as frequency-limited vertical columns from the very top of the ionogram to its bottom. Low-frequency noise (0.3-0.8 MHz) appear during auroral oval fly-throughs and are interpreted as a result of auroral kilometric radiation (AKR). Narrow bands on the magnetic gyrofrequency and upper hybrid frequency could be understood as an ionospheric plasma resonance response near the radiating antenna. Also, there are strong noises in the 3-5 MHz which we were not able to interpret. During some sounding sessions the transmitter was turned off so it was possible to record only natural and artificial noises and separate them from the ionospheric sounding responses.
Integrated siRNA design based on surveying of features associated with high RNAi effectiveness
Gong, Wuming; Ren, Yongliang; Xu, Qiqi; Wang, Yejun; Lin, Dong; Zhou, Haiyan; Li, Tongbin
Background Short interfering RNAs have allowed the development of clean and easily regulated methods for disruption of gene expression. However, while these methods continue to grow in popularity, designing effective siRNA experiments can be challenging. The various existing siRNA design guidelines suffer from two problems: they differ considerably from each other, and they produce high levels of false-positive predictions when tested on data of independent origins. Results Using a distinctly large set of siRNA efficacy data assembled from a vast diversity of origins (the siRecords data, containing records of 3,277 siRNA experiments targeting 1,518 genes, derived from 1,417 independent studies), we conducted extensive analyses of all known features that have been implicated in increasing RNAi effectiveness. A number of features having positive impacts on siRNA efficacy were identified. By performing quantitative analyses on cooperative effects among these features, then applying a disjunctive rule merging (DRM) algorithm, we developed a bundle of siRNA design rule sets with the false positive problem well curbed. A comparison with 15 online siRNA design tools indicated that some of the rule sets we developed surpassed all of these design tools commonly used in siRNA design practice in positive predictive values (PPVs). Conclusion The availability of the large and diverse siRNA dataset from siRecords and the approach we describe in this report have allowed the development of highly effective and generally applicable siRNA design rule sets. Together with ever improving RNAi lab techniques, these design rule sets are expected to make siRNAs a more useful tool for molecular genetics, functional genomics, and drug discovery studies. PMID:17129386
Scene Classfication Based on the Semantic-Feature Fusion Fully Sparse Topic Model for High Spatial Resolution Remote Sensing Imagery
NASA Astrophysics Data System (ADS)
Zhu, Qiqi; Zhong, Yanfei; Zhang, Liangpei
Topic modeling has been an increasingly mature method to bridge the semantic gap between the low-level features and high-level semantic information. However, with more and more high spatial resolution (HSR) images to deal with, conventional probabilistic topic model (PTM) usually presents the images with a dense semantic representation. This consumes more time and requires more storage space. In addition, due to the complex spectral and spatial information, a combination of multiple complementary features is proved to be an effective strategy to improve the performance for HSR image scene classification. But it should be noticed that how the distinct features are fused to fully describe the challenging HSR images, which is a critical factor for scene classification. In this paper, a semantic-feature fusion fully sparse topic model (SFF-FSTM) is proposed for HSR imagery scene classification. In SFF-FSTM, three heterogeneous features - the mean and standard deviation based spectral feature, wavelet based texture feature, and dense scale-invariant feature transform (SIFT) based structural feature are effectively fused at the latent semantic level. The combination of multiple semantic-feature fusion strategy and sparse based FSTM is able to provide adequate feature representations, and can achieve comparable performance with limited training samples. Experimental results on the UC Merced dataset and Google dataset of SIRI-WHU demonstrate that the proposed method can improve the performance of scene classification compared with other scene classification methods for HSR imagery.
Ovarian low and high grade serous carcinomas: hidden divergent features in the tumor microenvironment
Buttarelli, Marianna; Martinelli, Enrica; Mascilini, Floriana; Petrillo, Marco; Ferrandina, Gabriella; Scambia, Giovanni; Gallo, Daniela
Only recently low-grade serous carcinoma (LGSOC) of the ovary has been recognized as a disease entity distinct from the more common high-grade serous carcinoma (HGSOC), with significant differences in pathogenesis and clinical and pathologic features. The present study aimed at evaluating whether the different natural histories and patterns of response to therapy demonstrated for LGSOC and HGSOC, along with a diverse genomic landscape, may also reside in the supporting tumor stroma, specifically in the state of differentiation and activation of tumor associated macrophages (TAMs). TAMs play complex roles in tumorigenesis since they are believed to possess both tumor rejecting (M1 macrophages) and tumor promoting (M2 macrophages) activities. Here we showed that, when compared to HGSOC (n = 55), LGSOC patients (n = 25) exhibited lower density of tumor-infiltrating CD68+ macrophage, along with an attenuated M2-skewed (CD163+) phenotype. Accordingly, assessment of intratumoral vascularization and of matrix metalloproteinase 9 expression (a key protein involved in tumor invasion and metastasis) revealed lower expression in LGSOC compared to HGSOC patients, in line with emerging evidence supporting a role for TAMs in all aspects of tumor initiation, growth, and development. In conclusion, results from the present study demonstrate that microenvironmental factors contribute greatly to determine clinical and pathological features that differentiate low and high grade serous ovarian carcinomas. This understanding may increase possibilities and opportunities to improve disease control and design new therapeutic strategies. PMID:27462782
High-Velocity Features in Type Ia Supernovae from a Compact Circumstellar Shell
NASA Astrophysics Data System (ADS)
Mulligan, Brian W.; Wheeler, J. Craig
High-velocity features (HVF) of Ca prior to B-band maximum light are a ubiquitous property of Type Ia supernovae (SN Ia), but the origin of this high-velocity material is unknown. It may result from ejection of material during the explosion, detonation of material on the surface prior to the supernova, or interaction with a companion or material in the nearby environment. Here we introduce the methods we use to simulate the interaction of SN Ia ejecta with a shell of material surrounding the progenitor at a distance of less than 1 R⊙. Assuming free expansion, constant ion state and excitation temperature, we generate synthetic spectra from the data showing the effect of equation of state, explosion model, and the width, initial density profile, and mass of the shell on the appearance and temporal evolution of the Ca II near-infrared triplet (CaNIR). The Ca abundance of the shell is taken to be a free parameter. We compare the evolution of the pseudo-equivalent width (pEW) of the CaNIR feature resulting from these models to observational results. We find that the mass of the shell must be less than 0.012 ± 0.004 M⊙. We discuss potential ambiguities in observational methods of determining the pEW of the HVF.
High-precision image aided inertial navigation with known features: observability analysis and performance evaluation.
Jiang, Weiping; Wang, Li; Niu, Xiaoji; Zhang, Quan; Zhang, Hui; Tang, Min; Hu, Xiangyun
A high-precision image-aided inertial navigation system (INS) is proposed as an alternative to the carrier-phase-based differential Global Navigation Satellite Systems (CDGNSSs) when satellite-based navigation systems are unavailable. In this paper, the image/INS integrated algorithm is modeled by a tightly-coupled iterative extended Kalman filter (IEKF). Tightly-coupled integration ensures that the integrated system is reliable, even if few known feature points (i.e., less than three) are observed in the images. A new global observability analysis of this tightly-coupled integration is presented to guarantee that the system is observable under the necessary conditions. The analysis conclusions were verified by simulations and field tests. The field tests also indicate that high-precision position (centimeter-level) and attitude (half-degree-level)-integrated solutions can be achieved in a global reference.
Physiological and genomic features of highly alkaliphilic hydrogen-utilizing Betaproteobacteria from a continental serpentinizing site
Suzuki, Shino; Kuenen, J. Gijs; Schipper, Kira; van der Velde, Suzanne; Ishii, Shun'ichi; Wu, Angela; Sorokin, Dimitry Y.; Tenney, Aaron; Meng, XianYing; Morrill, Penny L.; Kamagata, Yoichi; Muyzer, Gerard; Nealson, Kenneth H.
Serpentinization, or the aqueous alteration of ultramafic rocks, results in challenging environments for life in continental sites due to the combination of extremely high pH, low salinity and lack of obvious electron acceptors and carbon sources. Nevertheless, certain Betaproteobacteria have been frequently observed in such environments. Here we describe physiological and genomic features of three related Betaproteobacterial strains isolated from highly alkaline (pH 11.6) serpentinizing springs at The Cedars, California. All three strains are obligate alkaliphiles with an optimum for growth at pH 11 and are capable of autotrophic growth with hydrogen, calcium carbonate and oxygen. The three strains exhibit differences, however, regarding the utilization of organic carbon and electron acceptors. Their global distribution and physiological, genomic and transcriptomic characteristics indicate that the strains are adapted to the alkaline and calcium-rich environments represented by the terrestrial serpentinizing ecosystems. We propose placing these strains in a new genus 'Serpentinomonas'. PMID:24845058
[Biologic mechanisms of mitotic abnormalities and chromosome number changes in malignant tumors].
Hegyi, Katalin
The main goal of this work was to study the effect of Aurora kinase expression on cell ploidy and tumorigenesis. Fifty invasive breast cancer, 50 diffuse large B-cell lymphoma and 10 reactive lymph node samples were recruited in the study. Because of the significant correlation with the overall cell proliferation rate, the overexpression of Aurora B could not be stated on the basis of kinase expressing tumor cell fractions alone. The relative expression of Aurora B kinase is better reflected by the AMI index which represents the Aurora B expression in relation to the whole proliferative fraction of the tumor. A higher relative Aurora B expression was associated with higher mitotic activity in B-cell lymphoma. FISH analysis of the AURKB locus did not show any gains or amplifications in the samples analyzed. On the other hand, we have observed the loss of the gene in breast carcinoma and lymphoma samples as well. A strong correlation was shown between AURKB and TP53 copy numbers: AURKB loss was associated with TP53 deletion in all samples. According to our results on breast carcinoma, losses at 17p13.1 and chromosome 17 aneusomy determined by FISH showed a statistically significant correlation. Our study presents the frequent occurrence of chromosome 17 aneusomy in breast carcinoma and B-cell lymphoma samples. Chromosome 17 aneusomy evaluated by FISH correlated with aneuploidy determined by flow cytometry. Direct correlation between kinase expression and ploidy could not be shown. The highest AMI values were seen in B-ALCL samples, and it was associated with high chromosome 17 copy numbers and mitotic activity. The damaged Aurora B kinase function results in regulatory deficiencies in the CPC complex leading to mitotic errors, while p53 deficiency helps malignant cells to survive due to insufficient activation of the intrinsic apoptotic pathways. The upregulation of Aurora kinase B function may cause error in an important mitotic checkpoint, thus resulting in
EEG oscillations entrain their phase to high-level features of speech sound.
Zoefel, Benedikt; VanRullen, Rufin
Phase entrainment of neural oscillations, the brain's adjustment to rhythmic stimulation, is a central component in recent theories of speech comprehension: the alignment between brain oscillations and speech sound improves speech intelligibility. However, phase entrainment to everyday speech sound could also be explained by oscillations passively following the low-level periodicities (e.g., in sound amplitude and spectral content) of auditory stimulation-and not by an adjustment to the speech rhythm per se. Recently, using novel speech/noise mixture stimuli, we have shown that behavioral performance can entrain to speech sound even when high-level features (including phonetic information) are not accompanied by fluctuations in sound amplitude and spectral content. In the present study, we report that neural phase entrainment might underlie our behavioral findings. We observed phase-locking between electroencephalogram (EEG) and speech sound in response not only to original (unprocessed) speech but also to our constructed "high-level" speech/noise mixture stimuli. Phase entrainment to original speech and speech/noise sound did not differ in the degree of entrainment, but rather in the actual phase difference between EEG signal and sound. Phase entrainment was not abolished when speech/noise stimuli were presented in reverse (which disrupts semantic processing), indicating that acoustic (rather than linguistic) high-level features play a major role in the observed neural entrainment. Our results provide further evidence for phase entrainment as a potential mechanism underlying speech processing and segmentation, and for the involvement of high-level processes in the adjustment to the rhythm of speech.
Mitotic Catastrophe in BC3H1 Cells following Yessotoxin Exposure
Korsnes, Mónica Suárez; Korsnes, Reinert
The marine toxin yessotoxin (YTX) can cause various cytotoxic effects depending on cell type and cell line. It is well known to trigger distinct mechanisms for programmed cell death which may overlap or cross-talk. The present contribution provides the first evidence that YTX can cause genotoxicity and induce mitotic catastrophe which can lead to different types of cell death. This work also demonstrates potential information gain from non-intrusive computer-based tracking of many individual cells during long time. Treatment of BC3H1 cells at their exponential growth phase causes atypical nuclear alterations and formation of giant cells with multiple nuclei. These are the most prominent morphological features of mitotic catastrophe. Giant cells undergo slow cell death in a necrosis-like manner. However, apoptotic-like cell death is also observed in these cells. Electron microscopy of treated BC3H1 cells reveal uncondensed chromatin and cells with double nuclei. Activation of p-p53, p-H2AX, p-Chk1, p-ATM, and p-ATR and down-regulation of p-Chk2 indicate DNA damage response and cell cycle deregulation. Micronuclei formation further support this evidence. Data from tracking single cells reveal that YTX treatment suppresses a second round of cell division in BC3H1 cells. These findings suggest that YTX can induce genomic alterations or imperfections in chromosomal segregation leading to permanent mitotic failure. This understanding extends the list of effects from YTX and which are of interest to control cancer and tumor progression.
Weighted simultaneous algebraic reconstruction technique for tomosynthesis imaging of objects with high-attenuation features
Levakhina, Y. M.; Mueller, J.; Buzug, T. M.; Duschka, R. L.; Vogt, F.; Barkhausen, J.
Purpose: This paper introduces a nonlinear weighting scheme into the backprojection operation within the simultaneous algebraic reconstruction technique (SART). It is designed for tomosynthesis imaging of objects with high-attenuation features in order to reduce limited angle artifacts. Methods: The algorithm estimates which projections potentially produce artifacts in a voxel. The contribution of those projections into the updating term is reduced. In order to identify those projections automatically, a four-dimensional backprojected space representation is used. Weighting coefficients are calculated based on a dissimilarity measure, evaluated in this space. For each combination of an angular view direction and a voxel position an individual weighting coefficient for the updating term is calculated. Results: The feasibility of the proposed approach is shown based on reconstructions of the following real three-dimensional tomosynthesis datasets: a mammography quality phantom, an apple with metal needles, a dried finger bone in water, and a human hand. Datasets have been acquired with a Siemens Mammomat Inspiration tomosynthesis device and reconstructed using SART with and without suggested weighting. Out-of-focus artifacts are described using line profiles and measured using standard deviation (STD) in the plane and below the plane which contains artifact-causing features. Artifacts distribution in axial direction is measured using an artifact spread function (ASF). The volumes reconstructed with the weighting scheme demonstrate the reduction of out-of-focus artifacts, lower STD (meaning reduction of artifacts), and narrower ASF compared to nonweighted SART reconstruction. It is achieved successfully for different kinds of structures: point-like structures such as phantom features, long structures such as metal needles, and fine structures such as trabecular bone structures. Conclusions: Results indicate the feasibility of the proposed algorithm to reduce typical
Targeting mitotic exit with hyperthermia or APC/C inhibition to increase paclitaxel efficacy.
Giovinazzi, Serena; Bellapu, Dhruv; Morozov, Viacheslav M; Ishov, Alexander M
Microtubule-poisoning drugs, such as Paclitaxel (or Taxol, PTX), are powerful and commonly used anti-neoplastic agents for the treatment of several malignancies. PTX triggers cell death, mainly through a mitotic arrest following the activation of the spindle assembly checkpoint (SAC). Cells treated with PTX slowly slip from this mitotic block and die by mitotic catastrophe. However, cancer cells can acquire or are intrinsically resistant to this drug, posing one of the main obstacles for PTX clinical effectiveness. In order to override PTX resistance and increase its efficacy, we investigated both the enhancement of mitotic slippage and the block of mitotic exit. To test these opposing strategies, we used physiological hyperthermia (HT) to force exit from PTX-induced mitotic block and the anaphase-promoting complex/cyclosome (APC/C) inhibitor, proTAME, to block mitotic exit. We observed that application of HT on PTX-treated cells forced mitotic slippage, as shown by the rapid decline of cyclin B levels and by microscopy analysis. Similarly, HT induced mitotic exit in cells blocked in mitosis by other antimitotic drugs, such as Nocodazole and the Aurora A inhibitor MLN8054, indicating a common effect of HT on mitotic cells. On the other hand, proTAME prevented mitotic exit of PTX and MLN8054 arrested cells, prolonged mitosis, and induced apoptosis. In addition, we showed that proTAME prevented HT-mediated mitotic exit, indicating that stress-induced APC/C activation is necessary for HT-induced mitotic slippage. Finally, HT significantly increased PTX cytotoxicity, regardless of cancer cells' sensitivity to PTX, and this activity was superior to the combination of PTX with pro-TAME. Our data suggested that forced mitotic exit of cells arrested in mitosis by anti-mitotic drugs, such as PTX, can be a more successful anticancer strategy than blocking mitotic exit by inactivation of the APC/C.
Cortical neurons gradually attain a post-mitotic state.
Anda, Froylan Calderon de; Madabhushi, Ram; Rei, Damien; Meng, Jia; Gräff, Johannes; Durak, Omer; Meletis, Konstantinos; Richter, Melanie; Schwanke, Birgit; Mungenast, Alison; Tsai, Li-Huei
Once generated, neurons are thought to permanently exit the cell cycle and become irreversibly differentiated. However, neither the precise point at which this post-mitotic state is attained nor the extent of its irreversibility is clearly defined. Here we report that newly born neurons from the upper layers of the mouse cortex, despite initiating axon and dendrite elongation, continue to drive gene expression from the neural progenitor tubulin α1 promoter (Tα1p). These observations suggest an ambiguous post-mitotic neuronal state. Whole transcriptome analysis of sorted upper cortical neurons further revealed that neurons continue to express genes related to cell cycle progression long after mitotic exit until at least post-natal day 3 (P3). These genes are however down-regulated thereafter, associated with a concomitant up-regulation of tumor suppressors at P5. Interestingly, newly born neurons located in the cortical plate (CP) at embryonic day 18-19 (E18-E19) and P3 challenged with calcium influx are found in S/G2/M phases of the cell cycle, and still able to undergo division at E18-E19 but not at P3. At P5 however, calcium influx becomes neurotoxic and leads instead to neuronal loss. Our data delineate an unexpected flexibility of cell cycle control in early born neurons, and describe how neurons transit to a post-mitotic state.
GSK3 Regulates Mitotic Chromosomal Alignment through CRMP4
Ong Tone, Stephan; Dayanandan, Bama
Background Glycogen Synthase Kinase 3 (GSK3) has been implicated in regulating chromosomal alignment and mitotic progression but the physiological substrates mediating these GSK3-dependent effects have not been identified. Collapsin Response Mediator Protein 4 (CRMP4) is a cytosolic phosphoprotein known to regulate cytoskeletal dynamics and is a known physiological substrate of GSK3. In this study, we investigate the role of CRMP4 during mitosis. Methodology and Principal Findings Here we demonstrate that during mitosis CRMP4 phosphorylation is regulated in a GSK3-dependent manner. We show that CRMP4 localizes to spindle microtubules during mitosis and loss of CRMP4 disrupts chromosomal alignment and mitotic progression. The effect of CRMP4 on chromosomal alignment is dependent on phosphorylation by GSK3 identifying CRMP4 as a critical GSK3 substrate during mitotic progression. We also provide mechanistic data demonstrating that CRMP4 regulates spindle microtubules consistent with its known role in the regulation of the microtubule cytoskeleton. Conclusion and Significance Our findings identify CRMP4 as a key physiological substrate of GSK3 in regulating chromosomal alignment and mitotic progression through its effect on spindle microtubules. PMID:21179545
Mitotic count by phosphohistone H3 immunohistochemical staining predicts survival and improves interobserver reproducibility in well-differentiated neuroendocrine tumors of the pancreas.
Voss, Sarah M; Riley, Meghan P; Lokhandwala, Parvez M; Wang, Ming; Yang, Zhaohai
Well-differentiated neuroendocrine tumors (WDNETs) of the pancreas are graded on the basis of mitotic count or Ki67 index. Mitotic count has a narrow cutoff; its assessment is time consuming and carries poor interobserver reproducibility. Phosphohistone H3 (PHH3) is a mitosis-specific marker whose value has been validated in several tumor types. We sought to assess the utility of PHH3 in histologic grading of pancreatic WDNETs. Sixty-three cases of surgically resected primary pancreatic WDNETs were retrieved, and immunohistochemical analysis for PHH3 and Ki67 was performed. Mitotic rate was independently assessed by 4 pathologists on hematoxylin and eosin (HE; in 50 high-power fields [HPFs], expressed as mitoses/10 HPF) and PHH3 stains (in 50 HPFs, one 10×, and one 20× hotspot). PHH3 and Ki67 labeling indices were determined on a single 20× hotspot and expressed as the percentage of positive cells to total cells. We found that mitotic counts by various methods significantly correlated with each other and also with PHH3 and Ki67 indices, with the best correlation seen within the 3 different PHH3 counts (in 50 HPFs, one 10× and one 20× hotspot). Moreover, mitotic count on PHH3 was less time consuming than that on HE (1.68 vs. 3.67 min for 50 HPFs, P<0.0001). Histologic grade determined by PHH3 significantly correlated with disease-specific and disease-free survivals, with the best cutoffs of ≥4 mitoses/10 HPF (2 mm), ≥7 mitoses/10× hotspot, ≥5 mitoses/20× hotspot (log rank test, P<0.0001), and ≥0.16% for PHH3 labeling index (log rank test, P<0.0006). Tumor grades based on PHH3 stain also showed significant correlation with patient survivals in multivariate Cox proportional hazards models (P<0.05). Histologic grades by mitotic counts on PHH3 demonstrated high concordance and κ agreement with grades determined by mitotic count on HE. PHH3 stain also showed improved interobserver agreement in both original mitotic count (intraclass correlation 0.98 vs. 0
Cytotoxic effects of cylindrospermopsin in mitotic and non-mitotic Vicia faba cells.
Garda, Tamás; Riba, Milán; Vasas, Gábor; Beyer, Dániel; M-Hamvas, Márta; Hajdu, Gréta; Tándor, Ildikó; Máthé, Csaba
Cylindrospermopsin (CYN) is a cyanobacterial toxin known as a eukaryotic protein synthesis inhibitor. We aimed to study its effects on growth, stress responses and mitosis of a eukaryotic model, Vicia faba (broad bean). Growth responses depended on exposure time (3 or 6d), cyanotoxin concentration, culture conditions (dark or continuous light) and V. faba cultivar ("Standard" or "ARC Egypt Cross"). At 6d of exposure, CYN had a transient stimulatory effect on root system growth, roots being possibly capable of detoxification. The toxin induced nucleus fragmentation, blebbing and chromosomal breaks indicating double stranded DNA breaks and programmed cell death. Root necrotic tissue was observed at 0.1-20 μg mL(-1) CYN that probably impeded toxin uptake into vascular tissue. Growth and cell death processes observed were general stress responses. In lateral root tip meristems, lower CYN concentrations (0.01-0.1 μg mL(-1)) induced the stimulation of mitosis and distinct mitotic phases, irrespective of culture conditions or the cultivar used. Higher cyanotoxin concentrations inhibited mitosis. Short-term exposure of hydroxylurea-synchronized roots to 5 μg mL(-1) CYN induced delay of mitosis that might have been related to a delay of de novo protein synthesis. CYN induced the formation of double, split and asymmetric preprophase bands (PPBs), in parallel with the alteration of cell division planes, related to the interference of cyanotoxin with protein synthesis, thus it was a plant- and CYN specific alteration.
Suppression of spindly delays mitotic exit and exacerbates cell death response of cancer cells treated with low doses of paclitaxel.
Silva, Patrícia M A; Ribeiro, Nilza; Lima, Raquel T; Andrade, Cláudia; Diogo, Vânia; Teixeira, Joana; Florindo, Cláudia; Tavares, Álvaro; Vasconcelos, M Helena; Bousbaa, Hassan
Microtubule-targeting agents (MTAs) are used extensively for the treatment of diverse types of cancer. They block cancer cells in mitosis through the activation of the spindle assembly checkpoint (SAC), the surveillance mechanism that ensures accurate chromosome segregation at the onset of anaphase. However, the cytotoxic activity of MTAs is limited by premature mitotic exit (mitotic slippage) due to SAC silencing. Here we have explored the dual role of the protein Spindly in chromosome attachments and SAC silencing to analyze the consequences of its depletion on the viability of tumor cells treated with clinically relevant doses of paclitaxel. As expected, siRNA-mediated Spindly suppression induced chromosome misalignment and accumulation of cells in mitosis. Remarkably, these cells were more sensitive to low-doses of paclitaxel. Sensitization was due to an increase in the length of mitotic arrest and high frequency of multinucleated cells, both correlated with an exacerbated post-mitotic cell death response as determined by cell fate profiling. Thus, by affecting both SAC silencing and chromosome attachment, Spindly targeting offers a double-edged sword that potentiates tumor cell killing by clinically relevant doses of paclitaxel, providing a rationale for combination chemotherapy against cancer.
Mio depletion links mTOR regulation to Aurora A and Plk1 activation at mitotic centrosomes.
Platani, Melpomeni; Trinkle-Mulcahy, Laura; Porter, Michael; Jeyaprakash, A Arockia; Earnshaw, William C
Coordination of cell growth and proliferation in response to nutrient supply is mediated by mammalian target of rapamycin (mTOR) signaling. In this study, we report that Mio, a highly conserved member of the SEACAT/GATOR2 complex necessary for the activation of mTORC1 kinase, plays a critical role in mitotic spindle formation and subsequent chromosome segregation by regulating the proper concentration of active key mitotic kinases Plk1 and Aurora A at centrosomes and spindle poles. Mio-depleted cells showed reduced activation of Plk1 and Aurora A kinase at spindle poles and an impaired localization of MCAK and HURP, two key regulators of mitotic spindle formation and known substrates of Aurora A kinase, resulting in spindle assembly and cytokinesis defects. Our results indicate that a major function of Mio in mitosis is to regulate the activation/deactivation of Plk1 and Aurora A, possibly by linking them to mTOR signaling in a pathway to promote faithful mitotic progression.
Mio depletion links mTOR regulation to Aurora A and Plk1 activation at mitotic centrosomes
Trinkle-Mulcahy, Laura; Porter, Michael; Jeyaprakash, A. Arockia
Coordination of cell growth and proliferation in response to nutrient supply is mediated by mammalian target of rapamycin (mTOR) signaling. In this study, we report that Mio, a highly conserved member of the SEACAT/GATOR2 complex necessary for the activation of mTORC1 kinase, plays a critical role in mitotic spindle formation and subsequent chromosome segregation by regulating the proper concentration of active key mitotic kinases Plk1 and Aurora A at centrosomes and spindle poles. Mio-depleted cells showed reduced activation of Plk1 and Aurora A kinase at spindle poles and an impaired localization of MCAK and HURP, two key regulators of mitotic spindle formation and known substrates of Aurora A kinase, resulting in spindle assembly and cytokinesis defects. Our results indicate that a major function of Mio in mitosis is to regulate the activation/deactivation of Plk1 and Aurora A, possibly by linking them to mTOR signaling in a pathway to promote faithful mitotic progression. PMID:26124292
Clinicopathological features of choledocholithiasis patients with high aminotransferase levels without cholangitis
Huh, Cheal Wung; Jang, Sung Ill; Lim, Beom Jin; Kim, Hee Wook; Kim, Jae Keun; Park, Jun Sung; Kim, Ja Kyung; Lee, Se Joon; Lee, Dong Ki
Abstract Common bile duct (CBD) stones are generally associated with greater elevations of alkaline phosphatase and gamma-glutamyl transpeptidase levels than aspartate aminotransferase and alanine aminotransferase levels. However, some patients with CBD stones show markedly increased aminotransferase levels, sometimes leading to the misdiagnosis of liver disease. Therefore, the aim of this study was to investigate the clinicopathologic features of patients with CBD stones and high aminotransferase levels. This prospective cohort study included 882 patients diagnosed with CBD stones using endoscopic retrograde cholangiopancreatography (ERCP). Among these patients, 38 (4.3%) exhibited aminotransferase levels above 400 IU/L without cholangitis (gallstone hepatitis [GSH] group), and 116 (13.2%) exhibited normal aminotransferase levels (control group). We compared groups in terms of clinical features, laboratory test results, radiologic images, and ERCP findings such as CBD diameter, CBD stone diameter and number, and periampullary diverticulum. Liver biopsy was performed for patients in the GSH group. GSH patients were younger and more likely to have gallbladder stones than control patients, implying a higher incidence of gallbladder stone migration. Also, GSH patients experienced more severe, short-lasting abdominal pain. ERCP showed narrower CBDs in GSH patients than in control patients. Histological analysis of liver tissue from GSH patients showed no abnormalities except for mild inflammation. Compared with control patients, GSH patients were younger and showed more severe, short-lasting abdominal pain, which could be due to a sudden increase of CBD pressure resulting from the migration of gallstones through narrower CBDs. These clinical features could be helpful not only for the differential diagnosis of liver disease but also for investigating the underlying mechanisms of liver damage in obstructive jaundice. Moreover, we propose a new definition of �
Mechanism of APC/CCDC20 activation by mitotic phosphorylation
Qiao, Renping; Weissmann, Florian; Yamaguchi, Masaya; Brown, Nicholas G.; VanderLinden, Ryan; Imre, Richard; Jarvis, Marc A.; Brunner, Michael R.; Davidson, Iain F.; Litos, Gabriele; Haselbach, David; Mechtler, Karl; Stark, Holger; Schulman, Brenda A.; Peters, Jan-Michael
Chromosome segregation and mitotic exit are initiated by the 1.2-MDa ubiquitin ligase APC/C (anaphase-promoting complex/cyclosome) and its coactivator CDC20 (cell division cycle 20). To avoid chromosome missegregation, APC/CCDC20 activation is tightly controlled. CDC20 only associates with APC/C in mitosis when APC/C has become phosphorylated and is further inhibited by a mitotic checkpoint complex until all chromosomes are bioriented on the spindle. APC/C contains 14 different types of subunits, most of which are phosphorylated in mitosis on multiple sites. However, it is unknown which of these phospho-sites enable APC/CCDC20 activation and by which mechanism. Here we have identified 68 evolutionarily conserved mitotic phospho-sites on human APC/C bound to CDC20 and have used the biGBac technique to generate 47 APC/C mutants in which either all 68 sites or subsets of them were replaced by nonphosphorylatable or phospho-mimicking residues. The characterization of these complexes in substrate ubiquitination and degradation assays indicates that phosphorylation of an N-terminal loop region in APC1 is sufficient for binding and activation of APC/C by CDC20. Deletion of the N-terminal APC1 loop enables APC/CCDC20 activation in the absence of mitotic phosphorylation or phospho-mimicking mutations. These results indicate that binding of CDC20 to APC/C is normally prevented by an autoinhibitory loop in APC1 and that its mitotic phosphorylation relieves this inhibition. The predicted location of the N-terminal APC1 loop implies that this loop controls interactions between the N-terminal domain of CDC20 and APC1 and APC8. These results reveal how APC/C phosphorylation enables CDC20 to bind and activate the APC/C in mitosis. PMID:27114510
A Hybrid Feature Subset Selection Algorithm for Analysis of High Correlation Proteomic Data
Kordy, Hussain Montazery; Baygi, Mohammad Hossein Miran; Moradi, Mohammad Hassan
Pathological changes within an organ can be reflected as proteomic patterns in biological fluids such as plasma, serum, and urine. The surface-enhanced laser desorption and ionization time-of-flight mass spectrometry (SELDI-TOF MS) has been used to generate proteomic profiles from biological fluids. Mass spectrometry yields redundant noisy data that the most data points are irrelevant features for differentiating between cancer and normal cases. In this paper, we have proposed a hybrid feature subset selection algorithm based on maximum-discrimination and minimum-correlation coupled with peak scoring criteria. Our algorithm has been applied to two independent SELDI-TOF MS datasets of ovarian cancer obtained from the NCI-FDA clinical proteomics databank. The proposed algorithm has used to extract a set of proteins as potential biomarkers in each dataset. We applied the linear discriminate analysis to identify the important biomarkers. The selected biomarkers have been able to successfully diagnose the ovarian cancer patients from the noncancer control group with an accuracy of 100%, a sensitivity of 100%, and a specificity of 100% in the two datasets. The hybrid algorithm has the advantage that increases reproducibility of selected biomarkers and able to find a small set of proteins with high discrimination power. PMID:23717808
The crystal structure of archaeal serine hydroxymethyltransferase reveals idiosyncratic features likely required to withstand high temperatures.
Angelucci, Francesco; Morea, Veronica; Angelaccio, Sebastiana; Saccoccia, Fulvio; Contestabile, Roberto; Ilari, Andrea
Serine hydroxymethyltransferases (SHMTs) play an essential role in one-carbon unit metabolism and are used in biomimetic reactions. We determined the crystal structure of free (apo) and pyridoxal-5'-phosphate-bound (holo) SHMT from Methanocaldococcus jannaschii, the first from a hyperthermophile, from the archaea domain of life and that uses H₄MPT as a cofactor, at 2.83 and 3.0 Å resolution, respectively. Idiosyncratic features were observed that are likely to contribute to structure stabilization. At the dimer interface, the C-terminal region folds in a unique fashion with respect to SHMTs from eubacteria and eukarya. At the active site, the conserved tyrosine does not make a cation-π interaction with an arginine like that observed in all other SHMT structures, but establishes an amide-aromatic interaction with Asn257, at a different sequence position. This asparagine residue is conserved and occurs almost exclusively in (hyper)thermophile SHMTs. This led us to formulate the hypothesis that removal of frustrated interactions (such as the Arg-Tyr cation-π interaction occurring in mesophile SHMTs) is an additional strategy of adaptation to high temperature. Both peculiar features may be tested by designing enzyme variants potentially endowed with improved stability for applications in biomimetic processes.
Correlation of Thermally Induced Pores with Microstructural Features Using High Energy X-rays
NASA Astrophysics Data System (ADS)
Menasche, David B.; Shade, Paul A.; Lind, Jonathan; Li, Shiu Fai; Bernier, Joel V.; Kenesei, Peter; Schuren, Jay C.; Suter, Robert M.
Combined application of a near-field High Energy Diffraction Microscopy measurement of crystal lattice orientation fields and a tomographic measurement of pore distributions in a sintered nickel-based superalloy sample allows pore locations to be correlated with microstructural features. Measurements were carried out at the Advanced Photon Source beamline 1-ID using an X-ray energy of 65 keV for each of the measurement modes. The nickel superalloy sample was prepared in such a way as to generate significant thermally induced porosity. A three-dimensionally resolved orientation map is directly overlaid with the tomographically determined pore map through a careful registration procedure. The data are shown to reliably reproduce the expected correlations between specific microstructural features (triple lines and quadruple nodes) and pore positions. With the statistics afforded by the 3D data set, we conclude that within statistical limits, pore formation does not depend on the relative orientations of the grains. The experimental procedures and analysis tools illustrated are being applied to a variety of materials problems in which local heterogeneities can affect materials properties.
Ki-67 proliferation index but not mitotic thresholds integrates the molecular prognostic stratification of lower grade gliomas.
Duregon, Eleonora; Bertero, Luca; Pittaro, Alessandra; Soffietti, Riccardo; Rudà, Roberta; Trevisan, Morena; Papotti, Mauro; Ventura, Laura; Senetta, Rebecca; Cassoni, Paola
Despite several molecular signatures for "lower grade diffuse gliomas" (LGG) have been identified, WHO grade still remains a cornerstone of treatment guidelines. Mitotic count bears a crucial role in its definition, although limited by the poor reproducibility of standard Hematoxylin & Eosin (H&E) evaluation. Phospho-histone-H3 (PHH3) and Ki-67 have been proposed as alternative assays of cellular proliferation. Therefore in the present series of 141 LGG, the molecular characterization (namely IDH status, 1p/19q co-deletion and MGMT promoter methylation) was integrated with the tumor "proliferative trait" (conventional H&E or PHH3-guided mitotic count and Ki-67 index) in term of prognosis definition. Exclusively high PHH3 and Ki-67 values were predictor of poor prognosis (log rank test, P = 0.0281 for PHH3 and P = 0.032 for Ki-67), unlike standard mitotic count. Based on Cox proportional hazard regression analyses, among all clinical (age), pathological (PHH3 and Ki-67) and molecular variables (IDH, 1p/19q codeletion and MGMT methylation) with a prognostic relevance at univariate survival analysis, only IDH expression (P = 0.001) and Ki-67 proliferation index (P = 0.027) proved to be independent prognostic factors. In addition, stratifying by IDH expression status, high Ki-67 retained its prognostic relevance uniquely in the IDH negative patient (P = 0.029) doubling their risk of death (hazard ratio = 2.27). Overall, PHH3 immunostaining is the sole reliable method with a prognostic value to highlight mitotic figures in LGG. Ki-67 proliferation index exceeds PHH3 mitotic count as a predictor of patient's prognosis, and should be integrated with molecular markers in a comprehensive grading system for LGG.
Distinctive features of kinetics of plasma at high specific energy deposition
NASA Astrophysics Data System (ADS)
Lepikhin, Nikita; Popov, Nikolay; Starikovskaia, Svetlana
A nanosecond capillary discharge in pure nitrogen at moderate pressures is used as an experimental tool for plasma kinetics studies at conditions of high specific deposited energy up to 1 eV/molecule. Experimental observations based on electrical (back current shunts, capacitive probe) and spectroscopic measurements (quenching rates; translational, rotational and vibrational temperature measurements) demonstrate that high specific deposited energy, at electric fields of 200-300 Td, can significantly change gas kinetics in the discharge and in the afterglow. The numerical calculations in 1D axially symmetric geometry using experimental data as input parameters show that changes in the plasma kinetics are caused by extremely high excitation degree: up to 10% of molecular nitrogen is electronically excited at present conditions. Distinctive features of kinetics of plasma at high specific energy deposition as well as details of the experimental technique and numerical calculations will be present. The work was partially supported by French National Agency, ANR (PLASMAFLAME Project, 2011 BS09 025 01), AOARD AFOSR, FA2386-13-1-4064 grant (Program Officer Prof. Chiping Li), LabEx Plas@Par and Linked International Laboratory LIA KaPPA (France-Russia).
High-resolution Mapping of Offshore and Onshore Glaciogenic Features in Melville Bay, Northwestern Greenland
NASA Astrophysics Data System (ADS)
Freire, F.; Gyllencreutz, R.; Greenwood, S.; Mayer, L. A.; Jakobsson, M.
This study presents results from high resolution mapping in the northwestern part of Greenland's continental shelf, offshore from the Greenland Ice Sheet. The study area is located at about 74o30'N and 58 o40'W where high-resolution seafloor imagery were collected from ~200-500 m water depth. These data were analyzed and compared to existing high-resolution satellite imagery of exposed glacial landforms from the nearby coastal areas. Offshore geophysical mapping equipment consisted of a Kongsberg EM2040 multibeam that was bow-mounted on the sailing vessel Explorer of Sweden together with a Seatex MRU5+ motion sensor and GPS antennas. In addition, a GAVIA autonomous underwater vehicle (AUV) from University of Iceland with installed Geoswath interfometric sonar and Marine Sonic side-scan was used. The data from these systems permitted the production of both 5-m (for the EM2040) and 2-m (for the Geoswath) resolution bathymetric grids for landform analyzes. Sediment characterization analysis was also undertaken using the co-registered backscatter data. The exposed onshore landforms were studied using data from the high-res QuickBird satellite images with a 2-m pixel resolution. Geomorphic analysis of the data shows that past tectonic and glacial scouring processes have shaped the present-day landscape in both the offshore and onshore study areas. The terrain consists of glacially eroded bedrock covered with very thin surficial sediments resembling a 'cnoc-and-lochan' terrain, although the degree of erosion varies spatially, probably as a result of local variations in the rock properties. Different glacially influenced features are identified and described in the study. These features have been used to understand and infer past ice-sheet processes, particularly ice-flow direction and the extent of ice-cover on the continental shelves from previous extreme glaciation events. The backscatter information from the high-resolution interferometric sonar show fine
MULTIPLE HIGH-VELOCITY SiO MASER FEATURES FROM THE HIGH-MASS PROTOSTAR W51 NORTH
Cho, Se-Hyung; Kim, Jaeheon; Byun, Do-Young E-mail: firstname.lastname@example.com
We present the detection of multiple high-velocity silicon monoxide (SiO v = 1, 2, J = 1-0) maser features in the high-mass protostar W51 North which are distributed over an exceedingly large velocity range from 105 to 230 km s{sup -1}. The SiO v = 1, J = 1-0 maser emission shows 3-5 narrow components which span a velocity range from 154 to 230 km s{sup -1} according to observational epochs. The SiO v = 2, J = 1-0 maser also shows 3-5 narrow components that do not correspond to the SiO v = 1 maser and span a velocity range from 105 to 154 km s{sup -1}. The multiple maser components show significant changes on very short timescales (<1 month) from epoch to epoch. We suggest that the high-velocity SiO masers may be emanated from massive star-forming activity of the W51 North protostar as SiO maser jets and will be a good probe of the earliest evolutionary stages of high-mass star formation via an accretion model. Further high angular resolution observations will be required for confirmation.
Bayesian Multiscale Analysis of X-Ray Jet Features in High Redshift Quasars
NASA Astrophysics Data System (ADS)
McKeough, Kathryn; Siemiginowska, A.; Kashyap, V.; Stein, N.
X-ray emission of powerful quasar jets may be a result of the inverse Compton (IC) process in which the Cosmic Microwave Background (CMB) photons gain energy by interactions with the jet's relativistic electrons. However, there is no definite evidence that IC/CMB process is responsible for the observed X-ray emission of large scale jets. A step toward understanding the X-ray emission process is to study the Radio and X-ray morphologies of the jet. We implement a sophisticated Bayesian image analysis program, Low-count Image Reconstruction and Analysis (LIRA) (Esch et al. 2004; Conners & van Dyk 2007), to analyze jet features in 11 Chandra images of high redshift quasars (z ~ 2 - 4.8). Out of the 36 regions where knots are visible in the radio jets, nine showed detectable X-ray emission. We measured the ratios of the X-ray and radio luminosities of the detected features and found that they are consistent with the CMB radiation relationship. We derived a range of the bulk lorentz factor (Γ) for detected jet features under the CMB jet emission model. There is no discernible trend of Γ with redshift within the sample. The efficiency of the X-ray emission between the detected jet feature and the corresponding quasar also shows no correlation with redshift. This work is supported in part by the National Science Foundation REU and the Department of Defense ASSURE programs under NSF Grant no.1262851 and by the Smithsonian Institution, and by NASA Contract NAS8-39073 to the Chandra X-ray Center (CXC). This research has made use of data obtained from the Chandra Data Archive and Chandra Source Catalog, and software provided by the CXC in the application packages CIAO, ChIPS, and Sherpa. We thank Teddy Cheung for providing the VLA radio images. Connors, A., & van Dyk, D. A. 2007, Statistical Challenges in Modern Astronomy IV, 371, 101 Esch, D. N., Connors, A., Karovska, M., & van Dyk, D. A. 2004, ApJ, 610, 1213
The mitotic checkpoint regulator RAE1 induces aggressive breast cancer cell phenotypes by mediating epithelial-mesenchymal transition
Oh, Ji Hoon; Hur, Ho; Lee, Ji-Yeon; Kim, Yeejeong; Seo, Younsoo; Kim, Myoung Hee
The gene RAE1 encodes ribonucleic acid export 1 (RAE1), which is involved in mRNA export and is known to serve as a mitotic checkpoint regulator. In addition, RAE1 haplo-insufficiency leads to chromosome missegregation and early aging-associated phenotypes. In humans, a positive correlation has been found between RAE1 copy number abnormalities and gene amplification in breast cancer cells. However, the precise functional role of RAE1 in breast cancer remains to be determined. An in silico analysis of data retrieved from GENT and cBio-Portal identified RAE1 upregulation in breast cancer tissues relative to normal breast cells. Functional studies of various cell lines showed that RAE1 induced invasive and migratory abilities by regulating epithelial-mesenchymal transition signals. A tissue microarray was constructed to demonstrate the interrelationship between clinicopathological features and RAE1 expression. Immunohistochemistry revealed a positive correlation between RAE1 expression and a high histologic grade. Furthermore, RAE1 overexpression was associated with considerably poorer disease-free survival and distant metastasis-free survival, especially in patients with oestrogen receptor-positive tumours. In summary, RAE1 may be a prognostic marker and therapeutic intervention target in malignant breast cancers. PMID:28181567
The mitotic checkpoint regulator RAE1 induces aggressive breast cancer cell phenotypes by mediating epithelial-mesenchymal transition.
Oh, Ji Hoon; Hur, Ho; Lee, Ji-Yeon; Kim, Yeejeong; Seo, Younsoo; Kim, Myoung Hee
The gene RAE1 encodes ribonucleic acid export 1 (RAE1), which is involved in mRNA export and is known to serve as a mitotic checkpoint regulator. In addition, RAE1 haplo-insufficiency leads to chromosome missegregation and early aging-associated phenotypes. In humans, a positive correlation has been found between RAE1 copy number abnormalities and gene amplification in breast cancer cells. However, the precise functional role of RAE1 in breast cancer remains to be determined. An in silico analysis of data retrieved from GENT and cBio-Portal identified RAE1 upregulation in breast cancer tissues relative to normal breast cells. Functional studies of various cell lines showed that RAE1 induced invasive and migratory abilities by regulating epithelial-mesenchymal transition signals. A tissue microarray was constructed to demonstrate the interrelationship between clinicopathological features and RAE1 expression. Immunohistochemistry revealed a positive correlation between RAE1 expression and a high histologic grade. Furthermore, RAE1 overexpression was associated with considerably poorer disease-free survival and distant metastasis-free survival, especially in patients with oestrogen receptor-positive tumours. In summary, RAE1 may be a prognostic marker and therapeutic intervention target in malignant breast cancers.
Induction of apoptosis by an inhibitor of the mitotic kinesin KSP requires both activation of the spindle assembly checkpoint and mitotic slippage.
Tao, Weikang; South, Victoria J; Zhang, Yun; Davide, Joseph P; Farrell, Linda; Kohl, Nancy E; Sepp-Lorenzino, Laura; Lobell, Robert B
The inhibition of KSP causes mitotic arrest by activating the spindle assembly checkpoint. While transient inhibition of KSP leads to reversible mitotic arrest, prolonged exposure to a KSP inhibitor induces apoptosis. Induction of apoptosis by the KSP inhibitor couples with mitotic slippage. Slippage-refractory cells show resistance to KSP inhibitor-mediated lethality, whereas promotion of slippage after mitotic arrest enhances apoptosis. However, attenuation of the spindle checkpoint confers resistance to KSP inhibitor-induced apoptosis. Furthermore, sustained KSP inhibition activates the proapoptotic protein, Bax, and both activation of the spindle checkpoint and subsequent mitotic slippage are required for Bax activation. These studies indicate that in response to KSP inhibition, activation of the spindle checkpoint followed by mitotic slippage initiates apoptosis by activating Bax.
Pharicin A, a novel natural ent-kaurene diterpenoid, induces mitotic arrest and mitotic catastrophe of cancer cells by interfering with BubR1 function.
Xu, Han-Zhang; Huang, Ying; Wu, Ying-Li; Zhao, Yong; Xiao, Wei-Lie; Lin, Qi-Shan; Sun, Han-Dong; Dai, Wei; Chen, Guo-Qiang
In this study, we report the functional characterization of a new ent-kaurene diterpenoid termed pharicin A, which was originally isolated from Isodon, a perennial shrub frequently used in Chinese folk medicine for tumor treatment. Pharicin A induces mitotic arrest in leukemia and solid tumor-derived cells identified by their morphology, DNA content and mitotic marker analyses. Pharicin A-induced mitotic arrest is associated with unaligned chromosomes, aberrant BubR1 localization and deregulated spindle checkpoint activation. Pharicin A directly binds to BubR1 in vitro, which is correlated with premature sister chromatid separation in vivo. Pharicin A also induces mitotic arrest in paclitaxel-resistant Jurkat and U2OS cells. Combined, our study strongly suggests that pharicin A represents a novel class of small molecule compounds capable of perturbing mitotic progression and initiating mitotic catastrophe, which merits further preclinical and clinical investigations for cancer drug development.
A Small Mission Featuring an Imaging X-ray Polarimeter with High Sensitivity
NASA Technical Reports Server (NTRS)
Weisskopf, Martin C.; Baldini, Luca; Bellazini, Ronaldo; Brez, Alessandro; Costa, Enrico; Dissley, Richard; Elsner, Ronald; Fabiani, Sergio; Matt, Giorgio; Minuti, Massimo; Mulieri, Fabio; O'Dell, Steve; Pinchera, Michelle; Ramsey, Brian; Rubini, Alda; Sgro, Carmelo; Soffitta, Paolo; Spandre, Gloria
We present a detailed description of a small mission capable of obtaining high precision and meaningful measurement of the X-ray polarization of a variety of different classes of cosmic X-ray sources. Compared to other ideas that have been suggested this experiment has demonstrated in the laboratory a number of extremely important features relevant to the ultimate selection of such a mission by a funding agency. The most important of these questions are: 1) Have you demonstrated the sensitivity to a polarized beam at the energies of interest (i.e. the energies which represent the majority (not the minority) of detected photons from the X-ray source of interest? 2) Have you demonstrated that the device's sensitivity to an unpolarized beam is really negligible and/or quantified the impact of any systematic effects upon actual measurements? We present our answers to these questions backed up by laboratory measurements and give an overview of the mission.
Sunspot groups with high flare activity: Specific features of magnetic configuration, morphology, and dynamics
NASA Astrophysics Data System (ADS)
Fursyak, Yu. A.
Specific features of the magnetic configuration, morphological structure, dynamics, and evolution of sunspot groups of the current (24th) cycle of solar activity with high flare activity are considered. The gradients of longitudinal magnetic fields at places of δ-configuration are calculated. The main finding is a time delay of 24-30 h between the time when the magnetic field gradient reaches a critical level of 0.1 G/km and the time when the first of powerful flares occurs in the active region. The study is based on data from the SDO and GOES-15 spacecrafts and ground-based solar telescopes (TST-2 at the Crimean Astrophysical Observatory of the Russian Academy of Sciences and the 150-foot telescope at the Mount Wilson Observatory).
Ion-neutral momentum coupling near discrete high-latitude ionospheric features
NASA Technical Reports Server (NTRS)
St-Maurice, J.-P.; Schunk, R. W.
A two-dimensional numerical model is developed to study the momentum coupling between the ionosphere and neutral atmosphere in the vicinity of discrete high-latitude features, such as convection channels and plasma density troughs. Based on generalized magnetohydrodynamic equations the model takes account of global pressure gradients, viscous dissipation, ion drag, the Coriolis force, and electrodynamic drifts. Among the findings of an initial steady state investigation are the following: (1) in convection channels, significant shears and rotations of the thermospheric flow can occur below 200 km if a minimum in the electron density profile is present between the E and F regions; (2) in convection channels, the thermospheric wind decreases with height in the F region owing to the effects of horizontal viscosity; and (3) at low altitudes, the boundaries of convection channels may produce Ekman spirals.
Nano features of Al/Au ultrasonic bond interface observed by high resolution transmission electron microscopy
Ji Hongjun; Li Mingyu Kim, Jong-Myung; Kim, Dae-Won; Wang Chunqing
Nano-scale interfacial details of ultrasonic AlSi1 wire wedge bonding to a Au/Ni/Cu pad were investigated using high resolution transmission electron microscopy (HRTEM). The intermetallic phase Au{sub 8}Al{sub 3} formed locally due to diffusion and reaction activated by ultrasound at the Al/Au bond interface. Multilayer sub-interfaces roughly parallel to the wire/pad interface were observed among this phase, and interdiffusional features near the Au pad resembled interference patterns, alternately dark and bright bars. Solid-state diffusion theory cannot be used to explain why such a thick compound formed within milliseconds at room temperature. The major formation of metallurgical bonds was attributed to ultrasonic cyclic vibration.
Cigarette design features in low-, middle-, and high-income countries.
Caruso, Rosalie V; O'Connor, Richard J
Previous studies have shown that country income grouping is correlated with cigarette engineering. Cigarettes (N = 111 brands) were purchased during 2008-2010 from 11 low-, middle-, and high-income countries to assess physical dimensions and an array of cigarette design features. Mean ventilation varied significantly across low- (7.5%), middle- (15.3%), and high-income (26.2%) countries (P ≤ 0.001). Differences across income groups were also seen in cigarette length (P = 0.001), length of the tipping paper (P = 0.01), filter weight (P = 0.017), number of vent rows (P = 0.003), per-cigarette tobacco weight (P = 0.04), and paper porosity (P = 0.008). Stepwise linear regression showed ventilation and tobacco length as major predictors of ISO tar yields in low-income countries (P = 0.909, 0.047), while tipping paper (P < 0.001), filter length (P < 0.001), number of vent rows (P = 0.014), and per-cigarette weight (P = 0.015) were predictors of tar yields in middle-income countries. Ventilation (P < 0.001), number of vent rows (P = 0.009), per-cigarette weight (P < 0.001), and filter diameter (P = 0.004) predicted tar yields in high-income countries. Health officials must be cognizant of cigarette design issues to provide effective regulation of tobacco products.
Reinforcement learning on slow features of high-dimensional input streams.
Legenstein, Robert; Wilbert, Niko; Wiskott, Laurenz
Humans and animals are able to learn complex behaviors based on a massive stream of sensory information from different modalities. Early animal studies have identified learning mechanisms that are based on reward and punishment such that animals tend to avoid actions that lead to punishment whereas rewarded actions are reinforced. However, most algorithms for reward-based learning are only applicable if the dimensionality of the state-space is sufficiently small or its structure is sufficiently simple. Therefore, the question arises how the problem of learning on high-dimensional data is solved in the brain. In this article, we propose a biologically plausible generic two-stage learning system that can directly be applied to raw high-dimensional input streams. The system is composed of a hierarchical slow feature analysis (SFA) network for preprocessing and a simple neural network on top that is trained based on rewards. We demonstrate by computer simulations that this generic architecture is able to learn quite demanding reinforcement learning tasks on high-dimensional visual input streams in a time that is comparable to the time needed when an explicit highly informative low-dimensional state-space representation is given instead of the high-dimensional visual input. The learning speed of the proposed architecture in a task similar to the Morris water maze task is comparable to that found in experimental studies with rats. This study thus supports the hypothesis that slowness learning is one important unsupervised learning principle utilized in the brain to form efficient state representations for behavioral learning.
Prioritizing spatial accuracy in high-resolution fMRI data using multivariate feature weight mapping
Buschmann, Tilo; Lohmann, Gabriele; Margulies, Daniel S.; Trampel, Robert; Turner, Robert
Although ultra-high-field fMRI at field strengths of 7T or above provides substantial gains in BOLD contrast-to-noise ratio, when very high-resolution fMRI is required such gains are inevitably reduced. The improvement in sensitivity provided by multivariate analysis techniques, as compared with univariate methods, then becomes especially welcome. Information mapping approaches are commonly used, such as the searchlight technique, which take into account the spatially distributed patterns of activation in order to predict stimulus conditions. However, the popular searchlight decoding technique, in particular, has been found to be prone to spatial inaccuracies. For instance, the spatial extent of informative areas is generally exaggerated, and their spatial configuration is distorted. We propose the combination of a non-parametric and permutation-based statistical framework with linear classifiers. We term this new combined method Feature Weight Mapping (FWM). The main goal of the proposed method is to map the specific contribution of each voxel to the classification decision while including a correction for the multiple comparisons problem. Next, we compare this new method to the searchlight approach using a simulation and ultra-high-field 7T experimental data. We found that the searchlight method led to spatial inaccuracies that are especially noticeable in high-resolution fMRI data. In contrast, FWM was more spatially precise, revealing both informative anatomical structures as well as the direction by which voxels contribute to the classification. By maximizing the spatial accuracy of ultra-high-field fMRI results, global multivariate methods provide a substantial improvement for characterizing structure-function relationships. PMID:24795548
RHAMM Promotes Interphase Microtubule Instability and Mitotic Spindle Integrity through MEK1/ERK1/2 Activity*
Tolg, Cornelia; Hamilton, Sara R.; Morningstar, Lyndsey; Zhang, Jing; Zhang, S.; Esguerra, Kenneth V.; Telmer, Patrick G.; Luyt, Len G.; Harrison, Rene; McCarthy, James B.; Turley, Eva A.
An oncogenic form of RHAMM (receptor for hyaluronan-mediated motility, mouse, amino acids 163–794 termed RHAMMΔ163) is a cell surface hyaluronan receptor and mitotic spindle protein that is highly expressed in aggressive human cancers. Its regulation of mitotic spindle integrity is thought to contribute to tumor progression, but the molecular mechanisms underlying this function have not previously been defined. Here, we report that intracellular RHAMMΔ163 modifies the stability of interphase and mitotic spindle microtubules through ERK1/2 activity. RHAMM−/− mouse embryonic fibroblasts exhibit strongly acetylated interphase microtubules, multi-pole mitotic spindles, aberrant chromosome segregation, and inappropriate cytokinesis during mitosis. These defects are rescued by either expression of RHAMM or mutant active MEK1. Mutational analyses show that RHAMMΔ163 binds to α- and β-tubulin protein via a carboxyl-terminal leucine zipper, but in vitro analyses indicate this interaction does not directly contribute to tubulin polymerization/stability. Co-immunoprecipitation and pulldown assays reveal complexes of RHAMMΔ163, ERK1/2-MEK1, and α- and β-tubulin and demonstrate direct binding of RHAMMΔ163 to ERK1 via a D-site motif. In vitro kinase analyses, expression of mutant RHAMMΔ163 defective in ERK1 binding in mouse embryonic fibroblasts, and blocking MEK1 activity collectively confirm that the effect of RHAMMΔ163 on interphase and mitotic spindle microtubules is mediated by ERK1/2 activity. Our results suggest a model wherein intracellular RHAMMΔ163 functions as an adaptor protein to control microtubule polymerization during interphase and mitosis as a result of localizing ERK1/2-MEK1 complexes to their tubulin-associated substrates. PMID:20558733
CAFÉ-Map: Context Aware Feature Mapping for mining high dimensional biomedical data.
Minhas, Fayyaz Ul Amir Afsar; Asif, Amina; Arif, Muhammad
Feature selection and ranking is of great importance in the analysis of biomedical data. In addition to reducing the number of features used in classification or other machine learning tasks, it allows us to extract meaningful biological and medical information from a machine learning model. Most existing approaches in this domain do not directly model the fact that the relative importance of features can be different in different regions of the feature space. In this work, we present a context aware feature ranking algorithm called CAFÉ-Map. CAFÉ-Map is a locally linear feature ranking framework that allows recognition of important features in any given region of the feature space or for any individual example. This allows for simultaneous classification and feature ranking in an interpretable manner. We have benchmarked CAFÉ-Map on a number of toy and real world biomedical data sets. Our comparative study with a number of published methods shows that CAFÉ-Map achieves better accuracies on these data sets. The top ranking features obtained through CAFÉ-Map in a gene profiling study correlate very well with the importance of different genes reported in the literature. Furthermore, CAFÉ-Map provides a more in-depth analysis of feature ranking at the level of individual examples.
Extraction of Airport Features from High Resolution Satellite Imagery for Design and Risk Assessment
NASA Technical Reports Server (NTRS)
Robinson, Chris; Qiu, You-Liang; Jensen, John R.; Schill, Steven R.; Floyd, Mike
The LPA Group, consisting of 17 offices located throughout the eastern and central United States is an architectural, engineering and planning firm specializing in the development of Airports, Roads and Bridges. The primary focus of this ARC project is concerned with assisting their aviation specialists who work in the areas of Airport Planning, Airfield Design, Landside Design, Terminal Building Planning and design, and various other construction services. The LPA Group wanted to test the utility of high-resolution commercial satellite imagery for the purpose of extracting airport elevation features in the glide path areas surrounding the Columbia Metropolitan Airport. By incorporating remote sensing techniques into their airport planning process, LPA wanted to investigate whether or not it is possible to save time and money while achieving the equivalent accuracy as traditional planning methods. The Affiliate Research Center (ARC) at the University of South Carolina investigated the use of remotely sensed imagery for the extraction of feature elevations in the glide path zone. A stereo pair of IKONOS panchromatic satellite images, which has a spatial resolution of 1 x 1 m, was used to determine elevations of aviation obstructions such as buildings, trees, towers and fence-lines. A validation dataset was provided by the LPA Group to assess the accuracy of the measurements derived from the IKONOS imagery. The initial goal of this project was to test the utility of IKONOS imagery in feature extraction using ERDAS Stereo Analyst. This goal was never achieved due to problems with ERDAS software support of the IKONOS sensor model and the unavailability of imperative sensor model information from Space Imaging. The obstacles encountered in this project pertaining to ERDAS Stereo Analyst and IKONOS imagery will be reviewed in more detail later in this report. As a result of the technical difficulties with Stereo Analyst, ERDAS OrthoBASE was used to derive aviation
Detailed Hydrographic Feature Extraction from High-Resolution LiDAR Data
Danny L. Anderson
Detailed hydrographic feature extraction from high-resolution light detection and ranging (LiDAR) data is investigated. Methods for quantitatively evaluating and comparing such extractions are presented, including the use of sinuosity and longitudinal root-mean-square-error (LRMSE). These metrics are then used to quantitatively compare stream networks in two studies. The first study examines the effect of raster cell size on watershed boundaries and stream networks delineated from LiDAR-derived digital elevation models (DEMs). The study confirmed that, with the greatly increased resolution of LiDAR data, smaller cell sizes generally yielded better stream network delineations, based on sinuosity and LRMSE. The second study demonstrates a new method of delineating a stream directly from LiDAR point clouds, without the intermediate step of deriving a DEM. Direct use of LiDAR point clouds could improve efficiency and accuracy of hydrographic feature extractions. The direct delineation method developed herein and termed "mDn", is an extension of the D8 method that has been used for several decades with gridded raster data. The method divides the region around a starting point into sectors, using the LiDAR data points within each sector to determine an average slope, and selecting the sector with the greatest downward slope to determine the direction of flow. An mDn delineation was compared with a traditional grid-based delineation, using TauDEM, and other readily available, common stream data sets. Although, the TauDEM delineation yielded a sinuosity that more closely matches the reference, the mDn delineation yielded a sinuosity that was higher than either the TauDEM method or the existing published stream delineations. Furthermore, stream delineation using the mDn method yielded the smallest LRMSE.
Implications of mitotic and meiotic irregularities in common beans (Phaseolus vulgaris L.).
Lima, D C; Braz, G T; Dos Reis, G B; Techio, V H; Davide, L C; de F B Abreu, A
The common bean has great social and economic importance in Brazil and is the subject of a high number of publications, especially in the fields of genetics and breeding. Breeding programs aim to increase grain yield; however, mitosis and meiosis represent under explored research areas that have a direct impact on grain yield. Therefore, the study of cell division could be another tool available to bean geneticists and breeders. The aim of this study was to investigate irregularities occurring during the cell cycle and meiosis in common bean. The common bean cultivar used was BRSMG Talismã, which owing to its high yield and grain quality is recommended for cultivation in Brazil. We classified the interphase nuclei, estimated the mitotic and meiotic index, grain pollen viability, and percentage of abnormalities in both processes. The mitotic index was 4.1%, the interphase nucleus was non-reticulated, and 19% of dividing somatic cells showed abnormal behavior. Meiosis also presented irregularities resulting in a meiotic index of 44.6%. Viability of pollen grains was 94.3%. These results indicate that the common bean cultivar BRSMG Talismã possesses repair mechanisms that compensate for changes by producing a large number of pollen grains. Another important strategy adopted by bean plants to ensure stability is the elimination of abnormal cells by apoptosis. As the common bean cultivar BRSMG Talismã is recommended for cultivation because of its good agronomic performance, it can be concluded that mitotic and meiotic irregularities have no negative influence on its grain quality and yield.
Application Prospects and Microstructural Features in Laser-Induced Rapidly Solidified High-Entropy Alloys
NASA Astrophysics Data System (ADS)
Zhang, Hui; Pan, Ye; He, Yi-Zhu; Wu, Ji-Li; Yue, T. M.; Guo, Sheng
Recently, high-entropy alloys (HEAs) have attracted much interest in the materials community, as they offer massive opportunities to observe new phenomena, explore new structure, and develop new materials. Particularly, it is attractive to prepare high-performance HEA coatings by laser-induced rapid solidification, which can be formed on the surface of components and parts in a variety of sizes and shapes with a lower cost in comparison with those bulk material fabrication methods. From the technical point of view, laser-induced rapid solidification could hamper the compositional segregation, improve the solubility in solid-solution phases, and lead to the strengthening effect by the grain refinement. This article reviews the recent work on the typical microstructural features and the mechanical and chemical properties in laser-induced rapidly solidified HEAs, and these data are compared with conventional Co- and Ni-based alloy coatings. The article concludes with suggestions for future research and development in HEAs, from considerations of their characteristic properties.
Whole Genome Mapping with Feature Sets from High-Throughput Sequencing Data
Pan, Yonglong; Wang, Xiaoming; Liu, Lin; Wang, Hao; Luo, Meizhong
A good physical map is essential to guide sequence assembly in de novo whole genome sequencing, especially when sequences are produced by high-throughput sequencing such as next-generation-sequencing (NGS) technology. We here present a novel method, Feature sets-based Genome Mapping (FGM). With FGM, physical map and draft whole genome sequences can be generated, anchored and integrated using the same data set of NGS sequences, independent of restriction digestion. Method model was created and parameters were inspected by simulations using the Arabidopsis genome sequence. In the simulations, when ~4.8X genome BAC library including 4,096 clones was used to sequence the whole genome, ~90% of clones were successfully connected to physical contigs, and 91.58% of genome sequences were mapped and connected to chromosomes. This method was experimentally verified using the existing physical map and genome sequence of rice. Of 4,064 clones covering 115 Mb sequence selected from ~3 tiles of 3 chromosomes of a rice draft physical map, 3,364 clones were reconstructed into physical contigs and 98 Mb sequences were integrated into the 3 chromosomes. The physical map-integrated draft genome sequences can provide permanent frameworks for eventually obtaining high-quality reference sequences by targeted sequencing, gap filling and combining other sequences. PMID:27611682
Cytoskeletal architecture of isolated mitotic spindle with special reference to microtubule-associated proteins and cytoplasmic dynein.
Hirokawa, N; Takemura, R; Hisanaga, S
We have studied cytoskeletal architectures of isolated mitotic apparatus from sea urchin eggs using quick-freeze, deep-etch electron microscopy. This method revealed the existence of an extensive three-dimensional network of straight and branching crossbridges between spindle microtubules. The surface of the spindle microtubules was almost entirely covered with hexagonally packed, small, round button-like structures which were very uniform in shape and size (approximately 8 nm in diameter), and these microtubule buttons frequently provided bases for crossbridges between adjacent microtubules. These structures were removed from the surface of microtubules by high salt (0.6 M NaCl) extraction. Microtubule-associated proteins (MAPs) and microtubules isolated from mitotic spindles which were mainly composed of a large amount of 75-kD protein and some high molecular mass (250 kD, 245 kD) proteins were polymerized in vitro and examined by quick-freeze, deep-etch electron microscopy. The surfaces of microtubules were entirely covered with the same hexagonally packed round buttons, the arrangement of which is intimately related to that of tubulin dimers. Short crossbridges and some longer crossbridges were also observed. High salt treatment (0.6 M NaCl) extracted both 75-kD protein and high molecular weight proteins and removed microtubule buttons and most of crossbridges from the surface of microtubules. Considering the relatively high amount of 75-kD protein among MAPs isolated from mitotic spindles, it is concluded that these microtubule buttons probably consist of 75-kD MAP and that some of the crossbridges in vivo could belong to MAPs. Another kind of granule, larger in size (11-26 nm in diameter), was also on occasion associated with the surface of microtubules of mitotic spindles. A fine sidearm sometimes connected the larger granule to adjacent microtubules. Localization of cytoplasmic dynein ATPase in the mitotic spindle was investigated by electron microscopic
High-Resolution Infrared Space Observatory Spectroscopy of the Unidentified 21 Micron Feature
NASA Technical Reports Server (NTRS)
Volk, Kevin; Kwok, Sun; Hrivnak, Bruce
We present Infrared Space Observatory SWS06 mode observations of the 21 micron feature in eight sources, including a first "detection of the feature in IRAS Z02229+6208. The observed feature peak-to-continuum ratios range from 0.13 in IRAS Z02229+6208 to 1.30 in IRAS 07134+1005. The normalized spectra, obtained by the removal of the underlying continua and by scaling the features to the same peak flux value. show that all features have the same intrinsic profile and peak wavelength. There is no evidence for any discrete substructure due to molecular bands in the observed spectra, suggesting that the 21 micron feature is due to either a solid substance or a mixture of many similarly structured large molecules.
The Endocrine Dyscrasia that Accompanies Menopause and Andropause Induces Aberrant Cell Cycle Signaling that Triggers Cell Cycle Reentry of Post-mitotic Neurons, Neurodysfunction, Neurodegeneration and Cognitive Disease
Atwood, Craig S.; Bowen, Richard L.
Sex hormones are the physiological factors that regulate neurogenesis during embryogenesis and continuing through adulthood. These hormones support the formation of brain structures such as dendritic spines, axons and synapses required for the capture of information (memories). Intriguingly, a recent animal study has demonstrated that induction of neurogenesis results in the loss of previously encoded memories in animals (e.g. infantile amnesia). In this connection, much evidence now indicates that Alzheimer's disease (AD) also involves aberrant re-entry of post-mitotic neurons into the cell cycle. Cell cycle abnormalities appear very early in the disease, prior to the appearance of plaques and tangles, and explain the biochemical, neuropathological and cognitive changes observed with disease progression. Since sex hormones control when and how neurons proliferate and differentiate, the endocrine dyscrasia that accompanies menopause and andropause is a key signaling event that impacts neurogenesis and the acquisition, processing, storage and recall of memories. Here we review the biochemical, epidemiological and clinical evidence that alterations in endocrine signaling with menopause and andropause drive the aberrant re-entry of post-mitotic neurons into an abortive cell cycle with neurite retraction that leads to neuron dysfunction and death. When the reproductive axis is in balance, luteinizing hormone (LH), and its fetal homolog, human chorionic gonadotropin (hCG), promote pluripotent human and totipotent murine embryonic stem cell and neuron proliferation. However, strong evidence supports menopausal/andropausal elevations in the ratio of LH:sex steroids as driving aberrant mitotic events mediated by the upregulation of tumor necrosis factor, amyloid-β precursor protein processing towards the production of mitogenic Aβ, and the activation of Cdk5, a key regulator of cell cycle progression and tau phosphorylation (a cardinal feature of both neurogenesis and
Genetic Particle Swarm Optimization–Based Feature Selection for Very-High-Resolution Remotely Sensed Imagery Object Change Detection
Chen, Qiang; Chen, Yunhao; Jiang, Weiguo
In the field of multiple features Object-Based Change Detection (OBCD) for very-high-resolution remotely sensed images, image objects have abundant features and feature selection affects the precision and efficiency of OBCD. Through object-based image analysis, this paper proposes a Genetic Particle Swarm Optimization (GPSO)-based feature selection algorithm to solve the optimization problem of feature selection in multiple features OBCD. We select the Ratio of Mean to Variance (RMV) as the fitness function of GPSO, and apply the proposed algorithm to the object-based hybrid multivariate alternative detection model. Two experiment cases on Worldview-2/3 images confirm that GPSO can significantly improve the speed of convergence, and effectively avoid the problem of premature convergence, relative to other feature selection algorithms. According to the accuracy evaluation of OBCD, GPSO is superior at overall accuracy (84.17% and 83.59%) and Kappa coefficient (0.6771 and 0.6314) than other algorithms. Moreover, the sensitivity analysis results show that the proposed algorithm is not easily influenced by the initial parameters, but the number of features to be selected and the size of the particle swarm would affect the algorithm. The comparison experiment results reveal that RMV is more suitable than other functions as the fitness function of GPSO-based feature selection algorithm. PMID:27483285
High-spectral resolution observations of the 3.29 micron emission feature: Comparison to QCC and PAHs
NASA Technical Reports Server (NTRS)
Tokunaga, Alan T.; Sellgren, Kris; Sakata, Akira; Wada, S.; Onaka, Takashi; Nakada, Y.; Nagata, T.
Two of the most promising explanations for the origin of the interstellar emission features observed at 3.29, 3.4, 6.2, 7.7, 8.6, and 11.3 microns are: quenched carbonaceous composite (QCC) and polycyclic aromatic hydrocarbons (PAHs). High resolution spectra are given of the 3.29 micron emission feature which were taken with the Cooled Grating Array Spectrometer at the NASA Infrared Telescope Facility and previously published. These spectra show that the peak wavelength of the 3.29 micron feature is located at 3.295 + or - 0.005 micron and that it is coincident with the peak absorbance of QCC. The peak wavelength of the 3.29 micron feature appears to be the same in all of the sources observed thus far. However, the width of the feature in HD 44179 and Elias 1 is only 0.023 micron, which is smaller than the 0.043 micron width in NGC 7027, IRAS 21282+5050, the Orion nebula, and BD+30 deg 3639. Spectra of NGC 7027, QCC, and PAHs is shown. QCC matches the 3.29 micron interstellar emission feature very closely in the wavelength of the peak, and it produces a single feature. On the other hand, PAHs rarely match the peak of the interstellar emission feature, and characteristically produce multiple features.
Universal features in the photoemission spectroscopy of high-temperature superconductors
Zhao, Junjing; Chatterjee, Utpal; Ai, Dingfei; Hinks, David G.; Zheng, Hong; Gu, G. D.; Castellan, John-Paul; Rosenkranz, Stephan; Claus, Helmut; Norman, Michael R.; Randeria, Mohit; Campuzano, Juan Carlos
The energy gap for electronic excitations is one of the most important characteristics of the superconducting state, as it directly reflects the pairing of electrons. In the copper–oxide high-temperature superconductors (HTSCs), a strongly anisotropic energy gap, which vanishes along high-symmetry directions, is a clear manifestation of the d-wave symmetry of the pairing. There is, however, a dramatic change in the form of the gap anisotropy with reduced carrier concentration (underdoping). Although the vanishing of the gap along the diagonal to the square Cu–O bond directions is robust, the doping dependence of the large gap along the Cu–O directions suggests that its origin might be different from pairing. It is thus tempting to associate the large gap with a second-order parameter distinct from superconductivity. We use angle-resolved photoemission spectroscopy to show that the two-gap behavior and the destruction of well-defined electronic excitations are not universal features of HTSCs, and depend sensitively on how the underdoped materials are prepared. Depending on cation substitution, underdoped samples either show two-gap behavior or not. In contrast, many other characteristics of HTSCs, such as the dome-like dependence of on doping, long-lived excitations along the diagonals to the Cu–O bonds, and an energy gap at the Brillouin zone boundary that decreases monotonically with doping while persisting above (the pseudogap), are present in all samples, irrespective of whether they exhibit two-gap behavior or not. Our results imply that universal aspects of high- superconductivity are relatively insensitive to differences in the electronic states along the Cu–O bond directions. PMID:24101464
Universal features in the photoemission spectroscopy of high-temperature superconductors.
Zhao, Junjing; Chatterjee, Utpal; Ai, Dingfei; Hinks, David G; Zheng, Hong; Gu, G D; Castellan, John-Paul; Rosenkranz, Stephan; Claus, Helmut; Norman, Michael R; Randeria, Mohit; Campuzano, Juan Carlos
The energy gap for electronic excitations is one of the most important characteristics of the superconducting state, as it directly reflects the pairing of electrons. In the copper-oxide high-temperature superconductors (HTSCs), a strongly anisotropic energy gap, which vanishes along high-symmetry directions, is a clear manifestation of the d-wave symmetry of the pairing. There is, however, a dramatic change in the form of the gap anisotropy with reduced carrier concentration (underdoping). Although the vanishing of the gap along the diagonal to the square Cu-O bond directions is robust, the doping dependence of the large gap along the Cu-O directions suggests that its origin might be different from pairing. It is thus tempting to associate the large gap with a second-order parameter distinct from superconductivity. We use angle-resolved photoemission spectroscopy to show that the two-gap behavior and the destruction of well-defined electronic excitations are not universal features of HTSCs, and depend sensitively on how the underdoped materials are prepared. Depending on cation substitution, underdoped samples either show two-gap behavior or not. In contrast, many other characteristics of HTSCs, such as the dome-like dependence of on doping, long-lived excitations along the diagonals to the Cu-O bonds, and an energy gap at the Brillouin zone boundary that decreases monotonically with doping while persisting above (the pseudogap), are present in all samples, irrespective of whether they exhibit two-gap behavior or not. Our results imply that universal aspects of high- superconductivity are relatively insensitive to differences in the electronic states along the Cu-O bond directions.
Mitotic Spindle Assembly in Land Plants: Molecules and Mechanisms
Yamada, Moé; Goshima, Gohta
In textbooks, the mitotic spindles of plants are often described separately from those of animals. How do they differ at the molecular and mechanistic levels? In this chapter, we first outline the process of mitotic spindle assembly in animals and land plants. We next discuss the conservation of spindle assembly factors based on database searches. Searches of >100 animal spindle assembly factors showed that the genes involved in this process are well conserved in plants, with the exception of two major missing elements: centrosomal components and subunits/regulators of the cytoplasmic dynein complex. We then describe the spindle and phragmoplast assembly mechanisms based on the data obtained from robust gene loss-of-function analyses using RNA interference (RNAi) or mutant plants. Finally, we discuss future research prospects of plant spindles. PMID:28125061
Brownian dynamics simulation of fission yeast mitotic spindle formation
NASA Astrophysics Data System (ADS)
Edelmaier, Christopher
The mitotic spindle segregates chromosomes during mitosis. The dynamics that establish bipolar spindle formation are not well understood. We have developed a computational model of fission-yeast mitotic spindle formation using Brownian dynamics and kinetic Monte Carlo methods. Our model includes rigid, dynamic microtubules, a spherical nuclear envelope, spindle pole bodies anchored in the nuclear envelope, and crosslinkers and crosslinking motor proteins. Crosslinkers and crosslinking motor proteins attach and detach in a grand canonical ensemble, and exert forces and torques on the attached microtubules. We have modeled increased affinity for crosslinking motor attachment to antiparallel microtubule pairs, and stabilization of microtubules in the interpolar bundle. We study parameters controlling the stability of the interpolar bundle and assembly of a bipolar spindle from initially adjacent spindle-pole bodies.
Analysis of the Functionality of the Mitotic Checkpoints.
Fraschini, Roberta
During cell division the main goal of the cell is to produce two daughter cells with the same genome as the mother, i.e., maintain its genetic stability. Since this issue is essential to preserve the cell ability to proliferate properly, all eukaryotic cells have developed several pathways, called mitotic checkpoints, that regulate mitotic entry, progression, and exit in response to different cellular signals. Given the evolutive conservation of mechanisms and proteins involved in the cell cycle control from yeast to humans, the budding yeast S. cerevisiae has been very helpful to gain insight in these complex regulations. Here, we describe how the checkpoint can be activated and which cellular phenotypes can be used as markers of checkpoint activation.
Mitotic activity in dorsal epidermis of Rana pipiens.
NASA Technical Reports Server (NTRS)
Garcia-Arce, H.; Mizell, S.
Study of statistically significant rhythms of mitotic division in dorsal epidermis of frogs, Rana pipiens, exposed to a 12:12 light:dark environment for 14 days. The results include the findings that (1) male animals have a primary period of 22 hr in summer and 18 hr in winter, (2) female animals have an 18 hr period, and (3) parapinealectomy and blinding abolish the rhythm.
Cyto-3D-print to attach mitotic cells.
Castroagudin, Michelle R; Zhai, Yujia; Li, Zhi; Marnell, Michael G; Glavy, Joseph S
The Cyto-3D-print is an adapter that adds cytospin capability to a standard centrifuge. Like standard cytospinning, Cyto-3D-print increases the surface attachment of mitotic cells while giving a higher degree of adaptability to other slide chambers than available commercial devices. The use of Cyto-3D-print is cost effective, safe, and applicable to many slide designs. It is durable enough for repeated use and made of biodegradable materials for environment-friendly disposal.
Pattern formation in stochastic systems: Magnetized billiards and mitotic spindles
NASA Astrophysics Data System (ADS)
Schaffner, Stuart C.
Physical systems that exhibit chaotic behavior or are subject to thermal noise are treated as random processes, especially if the state of the system cannot be measured precisely. Here we examine two such systems. The first is a single electron confined to a wedge-shaped section of a disk, called a billiard, in the presence of a uniform transverse magnetic field. The system exhibits a mixture of chaotic and nonchaotic behavior at different values of the magnetic field strength. If the size of the billiard is on the order of micrometers, as in a quantum dot, both quantum and classical analyses are necessary. The second system is a collection of stiff fibers, called microtubules, suspended in a fluid called the cytoplasm, and lying over chromosomes in a cell. The cytoplasm supplies molecular motors and fuel for the motors. The chromosomes supply motor attachment points. The combination causes the microtubules to self-assemble into a coherent structure called the mitotic spindle. This structure is vital to cell division in plants and animals. Elements of the mitotic spindle have sizes ranging from nanometers to micrometers, and all are subject to considerable thermal agitation. Mitotic spindle self-assembly occurs despite the randomizing effect of this thermal motion. We studied both systems by constructing physical models described by mathematical equations. From these we were able to perform computer simulations. For the billiard problem, we made innovative use of geometric symmetries. These symmetries allowed us to construct efficient representations of both classical and quantum systems. We found a new region of integrable trajectories for a magnetic field above that required to produce completely chaotic orbits. For the mitotic spindle, we were the first to demonstrate spindle self-assembly in a model that matches conditions reported by experimental biologists. Our simulations have shed significant light on which of the many elements in this complex system are
Novel syngeneic pseudo-orthotopic prostate cancer model: vascular, mitotic and apoptotic responses to castration.
Frost, Gregory I; Lustgarten, Joseph; Dudouet, Brigitte; Nyberg, Linda; Hartley-Asp, Beryl; Borgström, Per
We describe a novel syngeneic "pseudo-orthotopic" in vivo model of prostate cancer progression. Our model uses the dorsal skinfold chamber technique with fluorescence video microscopy and TRAMP-C2 tumor cells. The cells were transfected with a histone H2B-GFP fusion protein, permitting real-time measurement of tumor size, as well as mitotic and apoptotic indices. To generate a "pseudo-orthotopic" milieu, pieces of prostate tissue (10-15 mm2) from donor mice were implanted into the chambers of C57BL/6 mice. The prostate tissue grafted into the chambers retained its native vasculature, as determined by transplantation of prostate tissue from GFP transgenic mice. TRAMP-C2 prostate cancer tumor spheroids (25,000 cells) were implanted in the chamber. Without prostate tissue, TRAMP-C2 prostate tumors were poorly angiogenic, displayed low mitotic and apoptotic indices (0.7 x 10(-4)), and no significant tumor growth could be detected. TRAMP-C2 tumors growing on transplanted prostate tissue in the chamber on the other hand had mitotic indices in the order of 1.6 x 10(-4) and apoptotic indices in the order of 0.8 x 10(-4). Furthermore, tumors with stroma were highly angiogenic, and were fully vascularized within 7-10 days. During a 4-week observation period, the number of tumor cells increased by nearly 300%. We used the model to study the effects of surgical castration. The most profound response was a rapid vascular regression of the tumor vasculature. Castration also increased apoptotic indices within the tumor without significant changes in mitosis. This model may be utilized for the rapid analysis of new therapeutic candidates against prostate cancer.
Insulin growth factors regulate the mitotic cycle in cultured rat sympathetic neuroblasts.
DiCicco-Bloom, E; Black, I B
While neuronal mitosis is uniquely restricted to early development, the underlying regulation remains to be defined. We have now developed a dissociated, embryonic sympathetic neuron culture system that uses fully defined medium in which cells enter the mitotic cycle. The cultured cells expressed two neuronal traits, tyrosine hydroxylase [L-tyrosine, tetrahydropteridine:oxygen oxidoreductase (3-hydroxylating); EC 22.214.171.124] and the neuron-specific 160-kDa neurofilament subunit protein, but were devoid of glial fibrillary acidic protein, a marker for non-myelin-forming Schwann cells in ganglia. Approximately one-third of the tyrosine hydroxylase-positive cells synthesized DNA in culture, specifically incorporating [3H]thymidine into their nuclei. We used this system to define factors regulating the mitotic cycle in sympathetic neuroblasts. Members of the insulin family of growth factors, including insulin and insulin-like growth factors I and II, regulated DNA synthesis in the presumptive neuroblasts. Insulin more than doubled the proportion of tyrosine hydroxylase-positive cells entering the mitotic cycle, as indicated by autoradiography of [3H]thymidine incorporation into nuclei. Scintillation spectrometry was an even more sensitive index of DNA synthesis, revealing a 4-fold insulin stimulation with an ED50 of 100 ng/ml. Insulin-like growth factor I was 100-fold more potent than insulin, whereas insulin-like growth factor II was less potent, suggesting that insulin growth factor type I receptors mediated the mitogenic responses. In contrast, the trophic protein nerve growth factor exhibited no mitogenic effect, suggesting that the mitogenic action of insulin growth factors is highly specific. Our observations are discussed in the context of the detection of insulin growth factors and receptors in the developing brain.
A roller coaster ride with the mitotic cyclins.
Fung, Tsz Kan; Poon, Randy Y C
Cyclins are discovered as proteins that accumulate progressively through interphase and disappear abruptly at mitosis during each cell cycle. In mammalian cells, cyclin A accumulates from late G1 phase and is destroyed before metaphase, and cyclin B is destroyed slightly later at anaphase. The abundance of the mitotic cyclins is mainly regulated at the levels of transcription and proteolysis. Transcription is stimulated and repressed by several transcription factors, including B-MYB, E2F, FOXM1, and NF-Y. Elements in the promoter, including CCRE/CDE and CHR, are in part responsible for the cell cycle oscillation of transcription. Destruction of the mitotic cyclins is carried out by the ubiquitin ligases APC/C(CDC20) and APC/C(CDH1). Central to our knowledge is the understanding of how APC/C is turned on from anaphase to early G1 phase, and turned off from late G1 till the spindle-assembly checkpoint is deactivated in metaphase. Reciprocal actions of cyclin-dependent kinases (CDKs) on APC/C, as well as on the SCF complexes ensure that the mitotic cyclins are destroyed only at the proper time.
Influence of centriole number on mitotic spindle length and symmetry
Keller, Lani C.; Wemmer, Kimberly A.; Marshall, Wallace F.
The functional role of centrioles or basal bodies in mitotic spindle assembly and function is currently unclear. Although supernumerary centrioles have been associated with multipolar spindles in cancer cells, suggesting centriole number might dictate spindle polarity, bipolar spindles are able to assembly in the complete absence of centrioles, suggesting a level of centriole-independence in the spindle assembly pathway. In this report we perturb centriole number using mutations in Chlamydomonas reinhardtii, and measure the response of the mitotic spindle to these perturbations in centriole number. Although altered centriole number increased the frequency of monopolar and multipolar spindles, the majority of spindles remained bipolar regardless of the centriole number. But even when spindles were bipolar, abnormal centriole numbers led to asymmetries in tubulin distribution, half-spindle length and spindle pole focus. Half spindle length correlated directly with number of centrioles at a pole, such that an imbalance in centriole number between the two poles of a bipolar spindle correlated with increased asymmetry between half spindle lengths. These results are consistent with centrioles playing an active role in regulating mitotic spindle length. Mutants with centriole number alteration also show increased cytokinesis defects, but these do not correlate with centriole number in the dividing cell and may therefore reflect downstream consequences of defects in preceding cell divisions. PMID:20540087
Proteins related to the spindle and checkpoint mitotic emphasize the different pathogenesis of hypoplastic MDS.
Heredia, Fabiola Fernandes; de Sousa, Juliana Cordeiro; Ribeiro Junior, Howard Lopes; Carvalho, Alex Fiorini; Magalhaes, Silvia Maria Meira; Pinheiro, Ronald Feitosa
Some studies show that alterations in expression of proteins related to mitotic spindle (AURORAS KINASE A and B) and mitotic checkpoint (CDC20 and MAD2L1) are involved in chromosomal instability and tumor progression in various solid and hematologic malignancies. This study aimed to evaluate these genes in MDS patients. The cytogenetics analysis was carried out by G-banding, AURKA and AURKB amplification was performed using FISH, and AURKA, AURKB, CDC20 and MAD2L1 gene expression was performed by qRT-PCR in 61 samples of bone marrow from MDS patients. AURKA gene amplification was observed in 10% of the cases, which also showed higher expression levels than the control group (p=0.038). Patients with normo/hypercellular BM presented significantly higher expression levels than hypocellular BM patients, but normo and hypercellular BM groups did not differ. After logistic regression analysis, our results showed that HIGH expression levels were associated with increased risk of developing normo/hypercellular MDS. It also indicated that age is associated with AURKA, CDC20 and MAD2L1 HIGH expression levels. The distinct expression of hypocellular patients emphasizes the prognostic importance of cellularity to MDS. The amplification/high expression of AURKA suggests that the increased expression of this gene may be related to the pathogenesis of disease.
Etching of Silicon in HBr Plasmas for High Aspect Ratio Features
NASA Technical Reports Server (NTRS)
Hwang, Helen H.; Meyyappan, M.; Mathad, G. S.; Ranade, R.
Etching in semiconductor processing typically involves using halides because of the relatively fast rates. Bromine containing plasmas can generate high aspect ratio trenches, desirable for DRAM and MEMS applications, with relatively straight sidewalk We present scanning electron microscope images for silicon-etched trenches in a HBr plasma. Using a feature profile simulation, we show that the removal yield parameter, or number of neutrals removed per incident ion due to all processes (sputtering, spontaneous desorption, etc.), dictates the profile shape. We find that the profile becomes pinched off when the removal yield is a constant, with a maximum aspect ratio (AR) of about 5 to 1 (depth to height). When the removal yield decreases with increasing ion angle, the etch rate increases at the comers and the trench bottom broadens. The profiles have ARs of over 9:1 for yields that vary with ion angle. To match the experimentally observed etched time of 250 s for an AR of 9:1 with a trench width of 0.135 microns, we find that the neutral flux must be 3.336 x 10(exp 17)sq cm/s.
High borides: determining the features and details of lattice dynamics from neutron spectroscopy
NASA Astrophysics Data System (ADS)
Alekseev, P. A.
We review wide-ranging research that combines inelastic neutron scattering spectroscopy with phenomenological and ab initio calculations to study the lattice dynamics and specifics of the electron-phonon interaction in three-dimensional boron cluster network systems M B_6 and M B12 ( M= {La}, {Sm}, and {Yb}, {Lu}, {Zr}). A close similarity is found between the atomic vibration spectra of these systems, which is fundamentally due to a strong hierarchy of interatomic interaction in these systems and which manifests itself both in the shape of the low-energy phonon dispersion and in the position of the high-energy edge of the spectrum. Manifestations of strong electron-phonon interactions in the lattice vibration spectra of borides are studied in detail and their relation to the nature and features of the valence-unstable state of rare-earth ions is examined. Resonance nonadiabaticity and magnetovibration interaction effects in spin- and valence-fluctuating systems are given special attention.
Some features of bulk melt-textured high-temperature superconductors subjected to alternating magnetic fields
NASA Astrophysics Data System (ADS)
Vanderbemden, P.; Molenberg, I.; Simeonova, P.; Lovchinov, V.
Monolithic, large grain, (RE)Ba2Cu3O7 high-temperature superconductors (where RE denotes a rare-earth ion) are known to be able to trap fields in excess of several teslas and represent thus an extremely promising competing technology for permanent magnet in several applications, e.g. in motors and generators. In any rotating machine, however, the superconducting permanent magnet is subjected to variable (transient, or alternating) parasitic magnetic fields. These magnetic fields interact with the superconductor, which yields a reduction of the remnant magnetization. In the present work we quantify these effects by analysing selected experimental data on bulk melt-textured superconductors subjected to AC fields. Our results indicate that the non-uniformity of superconducting properties in rather large samples might lead to unusual features and need to be taken into account to analyse the experimental data. We also investigate the evolution of the DC remnant magnetization of the bulk sample when it is subjected to a large number of AC magnetic field cycles, and investigate the experimental errors that result from a misorientation of the sample or a mispositioning of the Hall probe. The time-dependence of the remnant magnetization over 100000 cycles of the AC field is shown to display distinct regimes which all differ strongly from the usual decay due to magnetic relaxation.
The locomotory system of pearlfish Carapus acus: what morphological features are characteristic for highly flexible fishes?
Schwarz, Cathrin; Parmentier, Eric; Wiehr, Stefan; Gemballa, Sven
The body curvature displayed by fishes differs remarkably between species. Some nonmuscular features (e.g., number of vertebrae) are known to influence axial flexibility, but we have poor knowledge of the influence of the musculotendinous system (myosepta and muscles). Whereas this system has been described in stiff-bodied fishes, we have little data on flexible fishes. In this study, we present new data on the musculotendinous system of a highly flexible fish and compare them to existing data on rigid fishes. We use microdissections with polarized light microscopy to study the three-dimensional anatomy of myoseptal tendons, histology and immunohistology to study the insertion of muscle fiber types into tendons, and μ-CT scans to study skeletal anatomy. Results are compared with published data from stiff-bodied fishes. We identify four important morphological differences between stiff-bodied fishes and Carapus acus: (1) Carapus bears short tendons in the horizontal septum, whereas rigid fishes have elongated tendons. (2) Carapus bears short lateral tendons in its myosepta, whereas stiff-bodied fishes bear elongated tendons. Because of its short myoseptal tendons, Carapus retains high axial flexibility. In contrast, elongated tendons restrict axial flexibility in rigid fishes but are able to transmit anteriorly generated muscle forces through long tendons down to the tail. (3) Carapus bears distinct epineural and epipleural tendons in its myosepta, whereas these tendons are weak or absent in rigid fishes. As these tendons firmly connect vertebral axis and skin in Carapus, we consider them to constrain lateral displacement of the vertebral axis during extreme body flexures. (4) Ossifications of myoseptal tendons are only present in C. acus and other more flexible fishes but are absent in rigid fishes. The functional reasons for this remain unexplained.
Mitotic and polytene chromosome analysis in the Mexican fruit fly, Anastrepha ludens (Loew) (Diptera: Tephritidae).
Garcia-Martinez, V; Hernandez-Ortiz, E; Zepeta-Cisneros, C S; Robinson, A S; Zacharopoulou, A; Franz, G
The present study constitutes the first attempt to construct a polytene chromosome map of an Anastrepha species, Anastrepha ludens (Loew), a major agricultural pest. The mitotic karyotype has a diploid complement of 12 acrocentric chromosomes, including five pairs of autosomes and an XX/XY sex chromosome pair. The analysis of salivary gland polytene chromosomes has shown a total number of five polytene elements that correspond to the five autosomes. The characteristic features and the most prominent landmarks of each chromosome are described. By comparing chromosome banding patterns, the possible chromosomal homology between A. ludens and Ceratitis capitata (Wiedemann) is presented. This work shows that polytene maps of A. ludens are suitable for cytogenetic studies in this species and may be used as reference for other Anastrepha species, most of which are also serious agricultural pests.
Cbx2 stably associates with mitotic chromosomes via a PRC2- or PRC1-independent mechanism and is needed for recruiting PRC1 complex to mitotic chromosomes.
Zhen, Chao Yu; Duc, Huy Nguyen; Kokotovic, Marko; Phiel, Christopher J; Ren, Xiaojun
Polycomb group (PcG) proteins are epigenetic transcriptional factors that repress key developmental regulators and maintain cellular identity through mitosis via a poorly understood mechanism. Using quantitative live-cell imaging in mouse ES cells and tumor cells, we demonstrate that, although Polycomb repressive complex (PRC) 1 proteins (Cbx-family proteins, Ring1b, Mel18, and Phc1) exhibit variable capacities of association with mitotic chromosomes, Cbx2 overwhelmingly binds to mitotic chromosomes. The recruitment of Cbx2 to mitotic chromosomes is independent of PRC1 or PRC2, and Cbx2 is needed to recruit PRC1 complex to mitotic chromosomes. Quantitative fluorescence recovery after photobleaching analysis indicates that PRC1 proteins rapidly exchange at interphasic chromatin. On entry into mitosis, Cbx2, Ring1b, Mel18, and Phc1 proteins become immobilized at mitotic chromosomes, whereas other Cbx-family proteins dynamically bind to mitotic chromosomes. Depletion of PRC1 or PRC2 protein has no effect on the immobilization of Cbx2 on mitotic chromosomes. We find that the N-terminus of Cbx2 is needed for its recruitment to mitotic chromosomes, whereas the C-terminus is required for its immobilization. Thus these results provide fundamental insights into the molecular mechanisms of epigenetic inheritance.
The altitude of Neptune cloud features from high-spatial-resolution near-infrared spectra
NASA Astrophysics Data System (ADS)
Gibbard, S. G.; de Pater, I.; Roe, H. G.; Martin, S.; Macintosh, B. A.; Max, C. E.
We report on observations of Neptune from the 10-meter W.M. Keck II Telescope on June 17-18 (UT) 2000 and August 2-3 (UT) 2002 using the adaptive optics (AO) system to obtain a spatial resolution of 0.06 arcseconds. With this spatial resolution we can obtain spectra of individual bright features on the disk of Neptune in a filter centered near 2 microns. The use of a gas-only, simple reflecting layer radiative transfer model allows us to estimate the best fit altitudes of 18 bright features seen on these 4 nights and to set a constraint on the fraction of hydrogen in ortho/para equilibrium. On these nights there were three main types of features observed: northern hemisphere features in the range from +30 to -45 degrees; southern hemisphere features in the range from -30 to -50 degrees; and small southern features at -70 degrees. We find that the altitudes of the northern features are in the range from 0.023-0.064 bar, which places them in Neptune's stratosphere. Southern features at -30 to -50 degrees are mainly at altitudes from 0.10 to 0.14 bars. The small features at -70 degrees are somewhat deeper in the upper troposphere, at 0.17 and 0.27 bars. This pattern of features located at higher altitudes in the northern hemisphere and lower altitudes in the south has also been noted by previous observers. The best fits for all the observed spectra give a value of 1.0 for the fraction of hydrogen in ortho/para equilibrium; the value of the helium fraction is less well constrained by the data at 0.24. We suggest that the southern mid-latitude features are methane haze circulated up from below, while the -70° features may be isolated areas of upwelling in a general area of subsidence. Northern bright features may be due to subsidence of stratospheric haze material rather than upwelling and condensation of methane gas. We suggest that convection efficiently transports methane ice clouds to the tropopause in the Southern mid latitudes and thus plays a key role in the
AIBp regulates mitotic entry and mitotic spindle assembly by controlling activation of both Aurora-A and Plk1.
Chou, Chia-Hua; Loh, Joon-Khim; Yang, Ming-Chang; Lin, Ching-Chih; Hong, Ming-Chang; Cho, Chung-Lung; Chou, An-Kuo; Wang, Chi-Huei; Lieu, Ann-Shung; Howng, Shen-Long; Hsu, Ching-Mei; Hong, Yi-Ren
We previously reported that Aurora-A and the hNinein binding protein AIBp facilitate centrosomal structure maintenance and contribute to spindle formation. Here, we report that AIBp also interacts with Plk1, raising the possibility of functional similarity to Bora, which subsequently promotes Aurora-A-mediated Plk1 activation at Thr210 as well as Aurora-A activation at Thr288. In kinase assays, AIBp acts not only as a substrate but also as a positive regulator of both Aurora-A and Plk1. However, AIBp functions as a negative regulator to block phosphorylation of hNinein mediated by Aurora-A and Plk1. These findings suggest a novel AIBp-dependent regulatory machinery that controls mitotic entry. Additionally, knockdown of hNinein caused failure of AIBp to target the centrosome, whereas depletion of AIBp did not affect the localization of hNinein and microtubule nucleation. Notably, knockdown of AIBp in HeLa cells impaired both Aurora-A and Plk1 kinase, resulting in phenotypes with multiple spindle pole formation and chromosome misalignment. Our data show that depletion of AIBp results in the mis-localization of TACC3 and ch-TOG, but not CEP192 and CEP215, suggesting that loss of AIBp dominantly affects the Aurora-A substrate to cause mitotic aberrations. Collectively, our data demonstrate that AIBp contributes to mitotic entry and bipolar spindle assembly and may partially control localization, phosphorylation, and activation of both Aurora-A and Plk1 via hNinein during mitotic progression.
Robustness of features for automatic target discrimination in high-resolution polarimetric SAR data
NASA Astrophysics Data System (ADS)
van den Broek, Albertus C.; Dekker, Rob J.; Steeghs, Phillippe
We have studied the robustness of features against aspect variability for the purpose of target discrimination using polarimetric 35 Ghz ISAR data. Images at a resolution of 10 cm and 30 cm have been used for a complete aspect range of 360 degrees. The data covered four military targets: T72, ZSU23/4, T62, and BMP2. For the study we composed several feature vectors out of individual features extracted from the images. The features are divided into three categories: radiometric, geometric and polarimetric. We found that individual features show a strong variability as a function of aspect angle and cannot be used to discriminate between the targets irrespectively of the aspect angle. Using feature vectors and a maximum likelihood classifier reasonable discrimination (about 80%) between the four targets irrespective of the aspect angle was obtained at 10 cm resolution. At 30 cm resolution less significant discrimination (less than 70%) was found irrespective of the kind of feature vector used. In addition we investigated target discrimination per 30-degree aspect interval. In order to determine the aspect angle of targets we used a technique based on the Radon transformation, which gave an accuracy of about 5 degrees in aspect angle. We found that in this case good discrimination (more than 90%) was obtained at 10 cm resolution and reasonable discrimination (about 80%) at 30 cm resolution. The results are compared with analogous results from MSTAR data (30 cm resolution) of comparable targets.
Mitotic Index is an Independent Predictor of Recurrence-Free Survival in Meningioma.
Olar, Adriana; Wani, Khalida M; Sulman, Erik P; Mansouri, Alireza; Zadeh, Gelareh; Wilson, Charmaine D; DeMonte, Franco; Fuller, Gregory N; Aldape, Kenneth D
While World Health Organization (WHO) grading of meningioma stratifies patients according to recurrence risk overall, there is substantial within-grade heterogeneity with respect to recurrence-free survival (RFS). Most meningiomas are graded according to mitotic counts per unit area on hematoxylin and eosin sections, a method potentially confounded by tumor cellularity, as well as potential limitations of accurate mitotic figure detection on routine histology. To refine mitotic figure assessment, we evaluated 363 meningiomas with phospho-histone H3 (Ser10) and determined the mitotic index (number of mitoses per 1000 tumor cells). The median mitotic indices among WHO grade I (n = 268), grade II (n = 84) and grade III (n = 11) tumors were 1, 4 and 12. Classification and regression tree analysis to categorize cut-offs identified three subgroups defined by mitotic indices of 0-2, 3-4 and ≥5, which on univariate analysis were associated with RFS (P < 0.01). In multivariate analysis, mitotic index subgrouped in this manner was significantly associated with RFS (P < 0.01) after adjustment for Simpson grade, WHO grade and MIB-1 index. Mitotic index was then examined within individual WHO grade, showing that for grade I and grade II meningiomas, mitotic index can add additional information to RFS risk. The results suggest that the use of a robust mitotic marker in meningioma could refine risk stratification.
Integrative taxonomy of root-knot nematodes reveals multiple independent origins of mitotic parthenogenesis
Janssen, Toon; Karssen, Gerrit; Topalović, Olivera; Coyne, Danny; Bert, Wim
During sampling of several Coffea arabica plantations in Tanzania severe root galling, caused by a root-knot nematode was observed. From pure cultures, morphology and morphometrics of juveniles and females matched perfectly with Meloidogyne africana, whereas morphology of the males matched identically with those of Meloidogyne decalineata. Based on their Cox1 sequence, however, the recovered juveniles, females and males were confirmed to belong to the same species, creating a taxonomic conundrum. Adding further to this puzzle, re-examination of M. oteifae type material showed insufficient morphological evidence to maintain its status as a separate species. Consequently, M. decalineata and M. oteifae are synonymized with M. africana, which is herewith redescribed based on results of light and scanning electron microscopy, ribosomal and mitochondrial DNA sequences, isozyme electrophoresis, along with bionomic and cytogenetic features. Multi-gene phylogenetic analysis placed M. africana outside of the three major clades, together with M. coffeicola, M. ichinohei and M. camelliae. This phylogenetic position was confirmed by several morphological features, including cellular structure of the spermatheca, egg mass position, perineal pattern and head shape. Moreover, M. africana was found to be a polyphagous species, demonstrating that "early-branching" Meloidogyne spp. are not as oligophagous as had previously been assumed. Cytogenetic information indicates M. africana (2n = 21) and M. ardenensis (2n = 51–54) to be a triploid mitotic parthenogenetic species, revealing at least four independent origins of mitotic parthenogenesis within the genus Meloidogyne. Furthermore, M. mali (n = 12) was found to reproduce by amphimixis, indicating that amphimictic species with a limited number of chromosomes are widespread in the genus, potentially reflecting the ancestral state of the genus. The wide variation in chromosome numbers and associated changes in reproduction modes
High-spectral-resolution observations of the 7.7-micron feature in HD 44179
NASA Technical Reports Server (NTRS)
Russell, R. W.; Gull, G.; Beckwith, S.; Evans, N. J., II
Observations of the moon and HD 44179 were obtained in the wavelength range of 7.5-8.5 microns at a resolving power of approximately 800. The spectrum of the moon shows absorptions caused by telluric methane. Use of the moon as a calibrator is effective in removing these atmospheric lines. The spectrum of HD 44179 shows that the 7.7-micron emission feature does not break up into discrete, resolved emission features. Instead, it must be a broad, apparently continuous, emission feature.
Microdevice having interior cavity with high aspect ratio surface features and associated methods of manufacture and use
Morales, Alfredo M.
A microdevice having interior cavity with high aspect ratio features and ultrasmooth surfaces, and associated method of manufacture and use is described. An LIGA-produced shaped bit is used to contour polish the surface of a sacrificial mandrel. The contoured sacrificial mandrel is subsequently coated with a structural material and the mandrel removed to produce microdevices having micrometer-sized surface features and sub-micrometer RMS surface roughness.
Hsp72 is targeted to the mitotic spindle by Nek6 to promote K-fiber assembly and mitotic progression.
O'Regan, Laura; Sampson, Josephina; Richards, Mark W; Knebel, Axel; Roth, Daniel; Hood, Fiona E; Straube, Anne; Royle, Stephen J; Bayliss, Richard; Fry, Andrew M
Hsp70 proteins represent a family of chaperones that regulate cellular homeostasis and are required for cancer cell survival. However, their function and regulation in mitosis remain unknown. In this paper, we show that the major inducible cytoplasmic Hsp70 isoform, Hsp72, is required for assembly of a robust bipolar spindle capable of efficient chromosome congression. Mechanistically, Hsp72 associates with the K-fiber-stabilizing proteins, ch-TOG and TACC3, and promotes their interaction with each other and recruitment to spindle microtubules (MTs). Targeting of Hsp72 to the mitotic spindle is dependent on phosphorylation at Thr-66 within its nucleotide-binding domain by the Nek6 kinase. Phosphorylated Hsp72 concentrates on spindle poles and sites of MT-kinetochore attachment. A phosphomimetic Hsp72 mutant rescued defects in K-fiber assembly, ch-TOG/TACC3 recruitment and mitotic progression that also resulted from Nek6 depletion. We therefore propose that Nek6 facilitates association of Hsp72 with the mitotic spindle, where it promotes stable K-fiber assembly through recruitment of the ch-TOG-TACC3 complex.
Clinicopathologic Features and Clinical Outcomes of Esophageal Gastrointestinal Stromal Tumor
Feng, Fan; Tian, Yangzi; Liu, Zhen; Xu, Guanghui; Liu, Shushang; Guo, Man; Lian, Xiao; Fan, Daiming; Zhang, Hongwei
Abstract Clinicopathologic features and clinical outcomes of gastrointestinal stromal tumors (GISTs) in esophagus are limited, because of the relatively rare incidence of esophageal GISTs. Therefore, the aim of the current study was to investigate the clinicopathologic features and clinical outcomes of esophageal GISTs, and to investigate the potential factors that may predict prognosis. Esophageal GIST cases were obtained from our center and from case reports and clinical studies extracted from MEDLINE. Clinicopathologic features and survivals were analyzed and compared with gastric GISTs from our center. The most common location was lower esophagus (86.84%), followed by middle and upper esophagus (11.40% and 1.76%). The majority of esophageal GISTs were classified as high-risk category (70.83%). Mitotic index was correlated with histologic type, mutational status, and tumor size. The 5-year disease-free survival and disease-specific survival were 65.1% and 65.9%, respectively. Tumor size, mitotic index, and National Institutes of Health risk classification were associated with prognosis of esophageal GISTs. Only tumor size, however, was the independent risk factor for the prognosis of esophageal GISTs. In comparison to gastric GISTs, the distribution of tumor size, histologic type, and National Institutes of Health risk classification were significantly different between esophageal GISTs and gastric GISTs. The disease-free survival and disease-specific survival of esophageal GISTs were significantly lower than that of gastric GISTs. The most common location for esophageal GISTs was lower esophagus, and most of the esophageal GISTs are high-risk category. Tumor size was the independent risk factor for the prognosis of esophageal GISTs. Esophageal GISTs differ significantly from gastric GISTs in respect to clinicopathologic features. The prognosis of esophageal GISTs was worse than that of gastric GISTs. PMID:26765432
Tumor treating fields perturb the localization of septins and cause aberrant mitotic exit.
Gera, Nidhi; Yang, Aaron; Holtzman, Talia S; Lee, Sze Xian; Wong, Eric T; Swanson, Kenneth D
The anti-tumor effects of chemotherapy and radiation are thought to be mediated by triggering G1/S or G2/M cell cycle checkpoints, while spindle poisons, such as paclitaxel, block metaphase exit by initiating the spindle assembly checkpoint. In contrast, we have found that 150 kilohertz (kHz) alternating electric fields, also known as Tumor Treating Fields (TTFields), perturbed cells at the transition from metaphase to anaphase. Cells exposed to the TTFields during mitosis showed normal progression to this point, but exhibited uncontrolled membrane blebbing that coincided with metaphase exit. The ability of such alternating electric fields to affect cellular physiology is likely to be dependent on their interactions with proteins possessing high dipole moments. The mitotic Septin complex consisting of Septin 2, 6 and 7, possesses a high calculated dipole moment of 2711 Debyes (D) and plays a central role in positioning the cytokinetic cleavage furrow, and governing its contraction during ingression. We showed that during anaphase, TTFields inhibited Septin localization to the anaphase spindle midline and cytokinetic furrow, as well as its association with microtubules during cell attachment and spreading on fibronectin. After aberrant metaphase exit as a consequence of TTFields exposure, cells exhibited aberrant nuclear architecture and signs of cellular stress including an overall decrease in cellular proliferation, followed by apoptosis that was strongly influenced by the p53 mutational status. Thus, TTFields are able to diminish cell proliferation by specifically perturbing key proteins involved in cell division, leading to mitotic catastrophe and subsequent cell death.
Tumor Treating Fields Perturb the Localization of Septins and Cause Aberrant Mitotic Exit
Holtzman, Talia S.; Lee, Sze Xian; Wong, Eric T.; Swanson, Kenneth D.
The anti-tumor effects of chemotherapy and radiation are thought to be mediated by triggering G1/S or G2/M cell cycle checkpoints, while spindle poisons, such as paclitaxel, block metaphase exit by initiating the spindle assembly checkpoint. In contrast, we have found that 150 kilohertz (kHz) alternating electric fields, also known as Tumor Treating Fields (TTFields), perturbed cells at the transition from metaphase to anaphase. Cells exposed to the TTFields during mitosis showed normal progression to this point, but exhibited uncontrolled membrane blebbing that coincided with metaphase exit. The ability of such alternating electric fields to affect cellular physiology is likely to be dependent on their interactions with proteins possessing high dipole moments. The mitotic Septin complex consisting of Septin 2, 6 and 7, possesses a high calculated dipole moment of 2711 Debyes (D) and plays a central role in positioning the cytokinetic cleavage furrow, and governing its contraction during ingression. We showed that during anaphase, TTFields inhibited Septin localization to the anaphase spindle midline and cytokinetic furrow, as well as its association with microtubules during cell attachment and spreading on fibronectin. After aberrant metaphase exit as a consequence of TTFields exposure, cells exhibited aberrant nuclear architecture and signs of cellular stress including an overall decrease in cellular proliferation, followed by apoptosis that was strongly influenced by the p53 mutational status. Thus, TTFields are able to diminish cell proliferation by specifically perturbing key proteins involved in cell division, leading to mitotic catastrophe and subsequent cell death. PMID:26010837
An improved high order texture features extraction method with application to pathological diagnosis of colon lesions for CT colonography
NASA Astrophysics Data System (ADS)
Song, Bowen; Zhang, Guopeng; Lu, Hongbing; Wang, Huafeng; Han, Fangfang; Zhu, Wei; Liang, Zhengrong
Differentiation of colon lesions according to underlying pathology, e.g., neoplastic and non-neoplastic, is of fundamental importance for patient management. Image intensity based textural features have been recognized as a useful biomarker for the differentiation task. In this paper, we introduce high order texture features, beyond the intensity, such as gradient and curvature, for that task. Based on the Haralick texture analysis method, we introduce a virtual pathological method to explore the utility of texture features from high order differentiations, i.e., gradient and curvature, of the image intensity distribution. The texture features were validated on database consisting of 148 colon lesions, of which 35 are non-neoplastic lesions, using the random forest classifier and the merit of area under the curve (AUC) of the receiver operating characteristics. The results show that after applying the high order features, the AUC was improved from 0.8069 to 0.8544 in differentiating non-neoplastic lesion from neoplastic ones, e.g., hyperplastic polyps from tubular adenomas, tubulovillous adenomas and adenocarcinomas. The experimental results demonstrated that texture features from the higher order images can significantly improve the classification accuracy in pathological differentiation of colorectal lesions. The gain in differentiation capability shall increase the potential of computed tomography (CT) colonography for colorectal cancer screening by not only detecting polyps but also classifying them from optimal polyp management for the best outcome in personalized medicine.
The Spo12 protein of Saccharomyces cerevisiae: a regulator of mitotic exit whose cell cycle-dependent degradation is mediated by the anaphase-promoting complex.
Shah, R; Jensen, S; Frenz, L M; Johnson, A L; Johnston, L H
The Spo12 protein plays a regulatory role in two of the most fundamental processes of biology, mitosis and meiosis, and yet its biochemical function remains elusive. In this study we concentrate on the genetic and biochemical analysis of its mitotic function. Since high-copy SPO12 is able to suppress a wide variety of mitotic exit mutants, all of which arrest with high Clb-Cdc28 activity, we speculated whether SPO12 is able to facilitate exit from mitosis when overexpressed by antagonizing mitotic kinase activity. We show, however, that Spo12 is not a potent regulator of Clb-Cdc28 activity and can function independently of either the cyclin-dependent kinase inhibitor (CDKi), Sic1, or the anaphase-promoting complex (APC) regulator, Hct1. Spo12 protein level is regulated by the APC and the protein is degraded in G1 by an Hct1-dependent mechanism. We also demonstrate that in addition to localizing to the nucleus Spo12 is a nucleolar protein. We propose a model where overexpression of Spo12 may lead to the delocalization of a small amount of Cdc14 from the nucleolus, resulting in a sufficient lowering of mitotic kinase levels to facilitate mitotic exit. Finally, site-directed mutagenesis of highly conserved residues in the Spo12 protein sequence abolishes both its mitotic suppressor activity as well as its meiotic function. This result is the first indication that Spo12 may carry out the same biochemical function in mitosis as it does in meiosis. PMID:11729145
Adaptive semisupervised feature selection without graph construction for very-high-resolution remote sensing images
NASA Astrophysics Data System (ADS)
Chen, Xi; Qi, Jinzi; Chen, Yushi; Hua, Lizhong; Shao, Guofan
Semisupervised feature selection methods can improve classification performance and enhance model comprehensibility with few labeled objects. However, most of the existing methods require graph construction beforehand, and the resulting heavy computational cost may bring about the failure to accurately capture the local geometry of data. To overcome the problem, adaptive semisupervised feature selection (ASFS) is proposed. In ASFS, the goodness of each feature is measured by linear objective functions based on loss functions and probability distribution matrices. By alternatively optimizing model parameters and automatically adjusting the probabilities of boundary objects, ASFS can measure the genuine characteristics of the data and then rank and select features. The experimental results attest to the effectiveness and practicality of the method in comparison with the latest and state-of-the-art methods on a Worldview II image and a Quickbird II image.
Analysis of breast lesions on contrast-enhanced magnetic resonance images using high-dimensional texture features
NASA Astrophysics Data System (ADS)
Nagarajan, Mahesh B.; Huber, Markus B.; Schlossbauer, Thomas; Leinsinger, Gerda; Wismueller, Axel
Haralick texture features derived from gray-level co-occurrence matrices (GLCM) were used to classify the character of suspicious breast lesions as benign or malignant on dynamic contrast-enhanced MRI studies. Lesions were identified and annotated by an experienced radiologist on 54 MRI exams of female patients where histopathological reports were available prior to this investigation. GLCMs were then extracted from these 2D regions of interest (ROI) for four principal directions (0°, 45°, 90° & 135°) and used to compute Haralick texture features. A fuzzy k-nearest neighbor (k- NN) classifier was optimized in ten-fold cross-validation for each texture feature and the classification performance was calculated on an independent test set as a function of area under the ROC curve. The lesion ROIs were characterized by texture feature vectors containing the Haralick feature values computed from each directional-GLCM; and the classifier results obtained were compared to a previously used approach where the directional-GLCMs were summed to a nondirectional GLCM which could further yield a set of texture feature values. The impact of varying the inter-pixel distance while generating the GLCMs on the classifier's performance was also investigated. Classifier's AUC was found to significantly increase when the high-dimensional texture feature vector approach was pursued, and when features derived from GLCMs generated using different inter-pixel distances were incorporated into the classification task. These results indicate that lesion character classification accuracy could be improved by retaining the texture features derived from the different directional GLCMs rather than combining these to yield a set of scalar feature values instead.
Profiles of US and CT imaging features with a high probability of appendicitis
Laméris, W.; van Es, H. W.; ten Hove, W.; Bouma, W. H.; van Leeuwen, M. S.; van Keulen, E. M.; van der Hulst, V. P. M.; Henneman, O. D.; Bossuyt, P. M.; Boermeester, M. A.; Stoker, J.
Objectives To identify and evaluate profiles of US and CT features associated with acute appendicitis. Methods Consecutive patients presenting with acute abdominal pain at the emergency department were invited to participate in this study. All patients underwent US and CT. Imaging features known to be associated with appendicitis, and an imaging diagnosis were prospectively recorded by two independent radiologists. A final diagnosis was assigned after 6 months. Associations between appendiceal imaging features and a final diagnosis of appendicitis were evaluated with logistic regression analysis. Results Appendicitis was assigned to 284 of 942 evaluated patients (30%). All evaluated features were associated with appendicitis. Imaging profiles were created after multivariable logistic regression analysis. Of 147 patients with a thickened appendix, local transducer tenderness and peri-appendiceal fat infiltration on US, 139 (95%) had appendicitis. On CT, 119 patients in whom the appendix was completely visualised, thickened, with peri-appendiceal fat infiltration and appendiceal enhancement, 114 had a final diagnosis of appendicitis (96%). When at least two of these essential features were present on US or CT, sensitivity was 92% (95% CI 89–96%) and 96% (95% CI 93–98%), respectively. Conclusion Most patients with appendicitis can be categorised within a few imaging profiles on US and CT. When two of the essential features are present the diagnosis of appendicitis can be made accurately. PMID:20119730
Non-centrosomal nucleation mediated by augmin organizes microtubules in post-mitotic neurons and controls axonal microtubule polarity
Sánchez-Huertas, Carlos; Freixo, Francisco; Viais, Ricardo; Lacasa, Cristina; Soriano, Eduardo; Lüders, Jens
Neurons display a highly polarized microtubule network that mediates trafficking throughout the extensive cytoplasm and is crucial for neuronal differentiation and function. In newborn migrating neurons, the microtubule network is organized by the centrosome. During neuron maturation, however, the centrosome gradually loses this activity, and how microtubules are organized in more mature neurons remains poorly understood. Here, we demonstrate that microtubule organization in post-mitotic neurons strongly depends on non-centrosomal nucleation mediated by augmin and by the nucleator γTuRC. Disruption of either complex not only reduces microtubule density but also microtubule bundling. These microtubule defects impair neurite formation, interfere with axon specification and growth, and disrupt axonal trafficking. In axons augmin does not merely mediate nucleation of microtubules but ensures their uniform plus end-out orientation. Thus, the augmin-γTuRC module, initially identified in mitotic cells, may be commonly used to generate and maintain microtubule configurations with specific polarity. PMID:27405868
Classification of High Resolution C-Band PolSAR Data Based on Polarimetric and Texture Features
NASA Astrophysics Data System (ADS)
Zhao, Lei; Chen, Erxue; Li, Zengyuan; Feng, Qi; Li, Lan
PolSAR image classification is an important technique in the remote sensing area. For high resolution PolSAR image, polarimetric and texture features are equally important for the high resolution PolSAR image classification. The texture features are mainly extracted through Gray Level Co-occurrence Matrix (GLCM) method, but this method has some deficiencies. First, GLCM method can only work on gray-scale images; Secondly, the number of texture features extracted by GLCM method is generally up dozens, or even hundreds. Too many features may exist larger redundancy and will increase the complexity of classification. Therefore, this paper introduces a new texture feature factor-RK that derived from PolSAR image non-Gaussian statistic model. Using the domestic airborne C-band PolSAR image data, we completed classification combined the polarization and texture characteristics. The results showed that this new texture feature factor-RK can overcome the above drawbacks and can achieve same performance compared with GLCM method.
Artificial Neural Network for Probabilistic Feature Recognition in Liquid Chromatography Coupled to High-Resolution Mass Spectrometry.
Woldegebriel, Michael; Derks, Eduard
In this work, a novel probabilistic untargeted feature detection algorithm for liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS) using artificial neural network (ANN) is presented. The feature detection process is approached as a pattern recognition problem, and thus, ANN was utilized as an efficient feature recognition tool. Unlike most existing feature detection algorithms, with this approach, any suspected chromatographic profile (i.e., shape of a peak) can easily be incorporated by training the network, avoiding the need to perform computationally expensive regression methods with specific mathematical models. In addition, with this method, we have shown that the high-resolution raw data can be fully utilized without applying any arbitrary thresholds or data reduction, therefore improving the sensitivity of the method for compound identification purposes. Furthermore, opposed to existing deterministic (binary) approaches, this method rather estimates the probability of a feature being present/absent at a given point of interest, thus giving chance for all data points to be propagated down the data analysis pipeline, weighed with their probability. The algorithm was tested with data sets generated from spiked samples in forensic and food safety context and has shown promising results by detecting features for all compounds in a computationally reasonable time.
Influence of the circadian rhythm in cell division on radiation-induced mitotic delay in vivo
Rubin, N.H.
Mitotic delay is described as a classical response to radiation; however, circadian rhythmicity in cell division in vivo has not been considered by many authors. The present study investigated the relation between fluctuations reported as mitotic delay and recovery in vivo and circadian oscillations in mitotic index in mouse corneal epithelium. One aspect involved single doses (approximately 600 rad) given to mice at different circadian stages. The normal circadian rhythm in cell division was never obliterated. Inhibition of mitosis was evident but unpredictable, ranging from 6 to 15 hr after irradiation. Recovery was evident only during the daily increase in mitotic index of controls. The classical interpretation of recovery from mitotic delay may be in an in vitro phenomenon not reflecting in vivo responses, which are apparently strongly circadian stage dependent. The second portion of the study demonstrated a dose-response effect on length of mitotic delay and, to a lesser extent, degree of recovery.
Genome-wide siRNA screen reveals coupling between mitotic apoptosis and adaptation
Díaz-Martínez, Laura A; Karamysheva, Zemfira N; Warrington, Ross; Li, Bing; Wei, Shuguang; Xie, Xian-Jin; Roth, Michael G; Yu, Hongtao
The antimitotic anti-cancer drugs, including taxol, perturb spindle dynamics, and induce prolonged, spindle checkpoint-dependent mitotic arrest in cancer cells. These cells then either undergo apoptosis triggered by the intrinsic mitochondrial pathway or exit mitosis without proper cell division in an adaptation pathway. Using a genome-wide small interfering RNA (siRNA) screen in taxol-treated HeLa cells, we systematically identify components of the mitotic apoptosis and adaptation pathways. We show that the Mad2 inhibitor p31comet actively promotes mitotic adaptation through cyclin B1 degradation and has a minor separate function in suppressing apoptosis. Conversely, the pro-apoptotic Bcl2 family member, Noxa, is a critical initiator of mitotic cell death. Unexpectedly, the upstream components of the mitochondrial apoptosis pathway and the mitochondrial fission protein Drp1 contribute to mitotic adaption. Our results reveal crosstalk between the apoptosis and adaptation pathways during mitotic arrest. PMID:25024437
MEN, destruction and separation: mechanistic links between mitotic exit and cytokinesis in budding yeast.
Yeong, Foong May; Lim, Hong Hwa; Surana, Uttam
Cellular events must be executed in a certain sequence during the cell division in order to maintain genome integrity and hence ensure a cell's survival. In M phase, for instance, chromosome segregation always precedes mitotic exit (characterized by mitotic kinase inactivation via cyclin destruction); this is then followed by cytokinesis. How do cells impose this strict order? Recent findings in budding yeast have suggested a mechanism whereby partitioning of chromosomes into the daughter cell is a prerequisite for the activation of mitotic exit network (MEN). So far, however, a regulatory scheme that would temporally link the initiation of cytokinesis to the execution of mitotic exit has not been determined. We propose that the requirement of MEN components for cytokinesis, their translocation to the mother-daughter neck and triggering of this translocation by inactivation of the mitotic kinase may be the three crucial elements that render initiation of cytokinesis dependent on mitotic exit.
Mutations affecting mitotic recombination frequency in haploids and diploids of the filamentous fungus Aspergillus nidulans.
Parag, Y; Parag, G
A haploid strain of Asp. nidulans with a chromosome segment in duplicate (one in normal position on chromosome I, one translocated to chromosome II) shows mitotic recombination, mostly by conversion, in adE in a frequency slightly higher than in the equivalent diploid. A method has been devised, using this duplication, for the selection of rec and uvs mutations. Six rec mutations have been found which decrease recombination frequency in the haploid. One mutation selected as UV sensitive showed a hundred fold increase in recombination frequency in the haploid (pop mutation) and probably the same in diploids. The increased frequency is both in gene conversion and in crossing over, and the exchanges appear in clusters of two or more. pop is allelic to uvsB (Jansen, 1970) which had been found to affect mitotic but not meiotic recombination. It is suggested that mutations of this type interfere with the control mechanism which determines that high recombination is confirmed to the meiotic nuclei and avoided in somatic nuclei.
A three-dimensional approach to mitotic chromosome structure: evidence for a complex hierarchical organization
We describe findings on the architecture of Drosophila melanogaster mitotic chromosomes, made using a three-dimensional-oriented structural approach. Using high-voltage and conventional transmission electron microscopy combined with axial tomography and digital contrast- enhancement techniques, we have for the first time visualized significant structural detail within minimally perturbed mitotic chromosomes. Chromosomes prepared by several different preparative procedures showed a consistent size hierarchy of discrete chromatin structural domains with cross-sectional diameters of 120, 240, 400-500, and 800-1,000 A. In fully condensed, metaphase-arrested chromosomes, there is evidence for even larger-scale structural organization in the range of 1,300-3,000-A size. The observed intrachromosomal arrangements of these higher-order structural domains show that both the radial loop and sequential helical coiling models of chromosome structure are over- simplifications of the true situation. Finally, our results suggest that the pathway of chromatin condensation through mitosis consists of concurrent changes occurring at several levels of chromatin organization, rather than a strictly sequential folding process. PMID:3112167
Ectopic mitotic recombination in Drosophila probed with bacterial beta-galactosidase gene-based reporter transgenes.
Bärtsch, S; Dücker, K; Würgler, F E; Sengstag, C
Plasmids were constructed to investigate homologous mitotic recombination in Drosophila cells. Heteroalleles containing truncated but overlapping segments of the bacterial beta-galactosidase gene (lacZ) were positioned either on separate plasmids or as direct repeats on the same chromosome. Recombination reconstituted a functional lacZgene leading to expression of LacZ+activity detectable by histochemical staining. High extrachromosomal recombination (ECR) frequencies between unlinked heteroalleles were observed upon transient co-transfection into Drosophila melanogaster Schneider line 2 (S2) cells. Stably transfected cells containing the lacZ heteroalleles linked on a chromosome exhibited intrachromosomal recombination (ICR) frequencies two orders of magnitude lower than ECR frequencies. Recombination was inducible by exposing the cells to ethyl methanesulphonate or mitomycin C. Recombination products were characterized by multiplex PCR analysis and unequal sister chromatid recombination was found as the predominant mechanism reconstituting the lacZ gene. To investigate recombination in vivo imaginal disc cells from transgenic larvae carrying the reporter gene on the X chromosome were isolated and stained for LacZ+ activity. The presence of a few LacZ+ clones indicated that mitotic recombination events occurred at frequencies two orders of magnitude lower than the corresponding event in cultured cells and late during larval development. PMID:9380517
Titanium dioxide nanoparticles induce cytotoxicity and reduce mitotic index in human amniotic fluid-derived cells.
Acar, M S; Bulut, Z B; Ateş, A; Nami, B; Koçak, N; Yıldız, B
Titanium dioxide (TiO2) nanoparticles (NPs) are commonly used materials present in many consumables for which most people are exposed to. The biological hazards of the NPs on human health have been demonstrated previously. In this study, we aimed to assess the cytotoxicity potency of TiO2 NPs on the primary human amniotic fluid cells. The cells derived from amniotic fluid were treated with different dosages of TiO2 NPs for some periods. Cell adhesion status was assessed using a light microscopic observation. Cell proliferation and cell death rates were determined using trypan blue staining and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Also, mitotic index was determined using fluorescence in situ hybridization with chromosome 8 centromer-specific DNA probe. Disrupted cell adhesion, decreased proliferation, and increased mortality rates were detected in the cells that were treated with TiO2 NPs depending on the dosage (p < 0.001). Also, reduced mitotic index was determined in the cells depending on the time and TiO2 dosage when compared with the controls (p < 0.0001). These results showed that TiO2 NPs have high cytotoxicity for amniotic fluid-derived cells. Therefore, different products containing TiO2 NPs should be used with care, especially for pregnant women.
Redundant safety features in a high-channel-count retinal neurostimulator
Kelly, Shawn K.; Ellersick, William F.; Krishnan, Ashwati; Doyle, Patrick; Shire, Douglas B.; Wyatt, John L.; Rizzo, Joseph F.
Safety features embedded in a 256-channel retinal prosthesis integrated circuit are presented. The biology of the retina and the electrochemistry of the electrode-tissue interface demand careful planning and design of the safety features of an implantable retinal stimulation device. We describe the internal limits and communication safety features of our ASIC, but we focus on monitoring and protection circuits for the electrode-tissue interface. Two independent voltage monitoring circuits for each channel measure the electrode polarization voltage at two different times in the biphasic stimulation cycle. The monitors ensure that the charged electrode stays within the electrochemical water window potentials, and that the discharged electrode is within a small window near the counter electrode potential. A switch to connect each electrode to the counter electrode between pulses protects against a wide range of device failures. Additionally, we describe work on an active feedback system to ensure that the electrode voltage is at zero. PMID:27231724
Enhancement of spontaneous mitotic recombination by the meiotic mutant spo11-1 in Saccharomyces cerevisiae
Bruschi, C.V.; Esposito, M.S.
Both nonreciprocal and reciprocal mitotic recombination are enhanced by the recessive mutant spo11-1, which was previously shown to affect meiosis by decreasing recombination and increasing nondisjunction. The mitotic effects are not distributed equally in all chromosomal regions. The genotypes of mitotic recombinants in spo11-1/spo11-1 diploid cells provide further evidence that widely spaced chromosomal markers undergo coincident conversion in mitosis.
Comparison of Aerosol Classification from Airborne High Spectral Resolution Lidar and the CALIPSO Vertical Feature Mask
NASA Astrophysics Data System (ADS)
Burton, S. P.; Ferrare, R. A.; Omar, A. H.; Hostetler, C. A.; Hair, J. W.; Rogers, R.; Obland, M. D.; Butler, C. F.; Cook, A. L.; Harper, D. B.
The NASA Langley Research Center (LaRC) airborne High Spectral Resolution Lidar (HSRL-1) on the NASA B200 aircraft has acquired large datasets of aerosol extinction (532nm), backscatter (532 and 1064nm), and depolarization (532 and 1064nm) profiles during 349 science flights in 19 field missions across North America since 2006. The extinction-to-backscatter ratio ("lidar ratio"), aerosol depolarization ratios, and backscatter color ratio measurements from HSRL-1 are scale-invariant parameters that depend on aerosol type but not concentration. These four aerosol intensive parameters are combined to qualitatively classify HSRL aerosol measurements into eight separate composition types. The classification methodology uses models formed from "training cases" with known aerosol type. The remaining measurements are then compared with these models using the Mahalanobis distance. Aerosol products from the CALIPSO satellite include aerosol type information as well, which is used as input to the CALIPSO aerosol retrieval. CALIPSO aerosol types are inferred using a mix of aerosol loading-dependent parameters, estimated aerosol depolarization, and location, altitude, and surface type information. The HSRL instrument flies beneath the CALIPSO satellite orbit track, presenting the opportunity for comparisons between the HSRL aerosol typing and the CALIPSO Vertical Feature Mask Aerosol Subtype product, giving insight into the performance of the CALIPSO aerosol type algorithm. We find that the aerosol classification from the two instruments frequently agree for marine aerosols and pure dust, and somewhat less frequently for pollution and smoke. In addition, the comparison suggests that the CALIPSO polluted dust type is overly inclusive, encompassing cases of dust combined with marine aerosol as well as cases without much evidence of dust. Qualitative classification of aerosol type combined with quantitative profile measurements of aerosol backscatter and extinction has many useful
Mitotic Index Determined by Phosphohistone H3 Immunohistochemistry for Precise Grading in Follicular Lymphoma.
Bedekovics, Judit; Irsai, Gábor; Hegyi, Katalin; Beke, Lívia; Krenács, László; Gergely, Lajos; Méhes, Gábor
The World Health Organization classification recommends follicular lymphoma (FL) grading (G1-3) by considering centroblast number, while also suggesting its influence on disease outcome. As centroblast counting and other proliferation markers have limitations, we looked for more specific measures of cellular activity in FL. Phosphorylated histone H3 (pHH3) was widely applied for the objective detection of mitotic activity in different tumors. The aim was to evaluate the utility of pHH3 protein in FL grading and compare its value with the classical features of cell proliferation. Representative samples from 48 FL patients and 9 samples with follicular hyperplasia were examined. Hematoxylin-eosin-based mitosis index (HE-MI), number of mitotic figures based on anti-pHH3 immunohistochemical staining (pHH3-MI), and percentage of Ki-67-positive cells [proliferation index (PI)] were determined and compared with centroblast-based histologic grade. PHH3-MI showed significant correlation with HE-MI (r=0.85, P<0.0001) and PI (r=0.84, P<0.0001). All 3 cell proliferation parameters showed significant correlation with histologic grade: HE-MI versus grade, r=0.85 (P<0.0001); PI versus grade, r=0.74 (P<0.0001); pHH3-MI versus grade, r=0.80 (P<0.0001). PHH3-MI showed continuous increase with the histologic grade. The pHH3-MI value was distinctive between the G2 and the G1 FL groups (P<0.0001) and was increased in G3 FL compared with that in the G2 FL group (P=0.0020). In conclusion, easy-to-perform mitotic counting following phosphohistone H3 immunohistochemistry (pHH3-MI) correlates well with centroblast-based grading. PHH3 immunohistochemistry offers a reliable quantification tool supporting lymphoma grading and can be recommended as an additional parameter for the precise subcategorization of FL cases.
BCL-W is a regulator of microtubule inhibitor-induced mitotic cell death
Huang, Shan; Tang, Rui; Randy, Y.C. Poon
Microtubule inhibitors including taxanes and vinca alkaloids are among the most widely used anticancer agents. Disrupting the microtubules activates the spindle-assembly checkpoint and traps cells in mitosis. Whether cells subsequently undergo mitotic cell death is an important factor for the effectiveness of the anticancer agents. Given that apoptosis accounts for the majority of mitotic cell death induced by microtubule inhibitors, we performed a systematic study to determine which members of the anti-apoptotic BCL-2 family are involved in determining the duration of mitotic block before cell death or slippage. Depletion of several anti-apoptotic BCL-2-like proteins significantly shortened the time before apoptosis. Among these proteins, BCL-W has not been previously characterized to play a role in mitotic cell death. Although the expression of BCL-W remained constant during mitotic block, it varied significantly between different cell lines. Knockdown of BCL-W with siRNA or disruption of the BCL-W gene with CRISPR-Cas9 speeded up mitotic cell death. Conversely, overexpression of BCL-W delayed mitotic cell death, extending the mitotic block to allow mitotic slippage. Taken together, these results showed that BCL-W contributes to the threshold of anti-apoptotic activity during mitosis. PMID:27231850
Mitotically unstable polyploids in the yeast Pichia guilliermondii.
Klinner, U; Böttcher, F
Attempts to obtain triploids or tetraploids of P. guilliermondii by sexual hybridization led to mitotically stable hybrids. However, their DNA content per cell was not higher than in diploids. The results of random spore analysis demonstrate that these hybrids were in fact aneuploids which obviously suffered drastic chromosome losses immediately after mating. This phenomenon could have been caused either by aneuploidy already present in the parental strains or it might have been due to a general inability of P. guilliermondii to maintain a polyploid genome.
Cardinality as a highly descriptive feature in myoelectric pattern recognition for decoding motor volition
Ortiz-Catalan, Max
Accurate descriptors of muscular activity play an important role in clinical practice and rehabilitation research. Such descriptors are features of myoelectric signals extracted from sliding time windows. A wide variety of myoelectric features have been used as inputs to pattern recognition algorithms that aim to decode motor volition. The output of these algorithms can then be used to control limb prostheses, exoskeletons, and rehabilitation therapies. In the present study, cardinality is introduced and compared with traditional time-domain (Hudgins' set) and other recently proposed myoelectric features (for example, rough entropy). Cardinality was found to consistently outperform other features, including those that are more sophisticated and computationally expensive, despite variations in sampling frequency, time window length, contraction dynamics, type, and number of movements (single or simultaneous), and classification algorithms. Provided that the signal resolution is kept between 12 and 14 bits, cardinality improves myoelectric pattern recognition for the prediction of motion volition. This technology is instrumental for the rehabilitation of amputees and patients with motor impairments where myoelectric signals are viable. All code and data used in this work is available online within BioPatRec. PMID:26578873
An Educational System to Help Students Assess Website Features and Identify High-Risk Websites
ERIC Educational Resources Information Center
Kajiyama, Tomoko; Echizen, Isao
Purpose: The purpose of this paper is to propose an effective educational system to help students assess Web site risk by providing an environment in which students can better understand a Web site's features and determine the risks of accessing the Web site for themselves. Design/methodology/approach: The authors have enhanced a prototype…
With the Design in Mind: "High School Reform Model Features That Matter in Implementation." Conference Paper
ERIC Educational Resources Information Center
Shiffman, Catherine Dunn
This paper proposes a framework for analyzing program design features that seem to matter in implementation. The framework is based on findings from a study conducted by the Consortium for Policy Research in Education (CPRE) between 2004 and 2007 that explored how reform ideas and practices created by five external provider organizations were…
Assessment and prognostic significance of mitotic index using the mitosis marker phospho-histone H3 in low and intermediate-grade infiltrating astrocytomas.
Colman, Howard; Giannini, Caterina; Huang, Li; Gonzalez, Javier; Hess, Kenneth; Bruner, Janet; Fuller, Gregory; Langford, Lauren; Pelloski, Christopher; Aaron, Joann; Burger, Peter; Aldape, Ken
Distinguishing between grade II and grade III diffuse astrocytomas is important both for prognosis and for treatment decision-making. However, current methods for distinguishing between grades based on proliferative potential are suboptimal, making identification of clear cutoffs difficult. In this study, we compared the results from immunohistochemical staining for phospho-histone H3 (pHH3), a specific marker of cells undergoing mitosis, with standard mitotic counts (number of mitoses/10 high-power fields) and MIB-1 labeling index values for assessing proliferative activity. We tested the relationship between pHH3 staining and tumor grade and prognosis in a retrospective series of grade II and III infiltrating astrocytomas from a single institution. The pHH3 index (per 1000 cells), MIB-1 index (per 1000 cells), and number of mitoses per 10 high-power fields were determined for each of 103 cases of grade II and III diffuse astrocytomas from patients with clinical follow-up. pHH3 staining was found to be a simple and reliable method for identifying mitotic figures, allowing a true mitotic index to be determined. The pHH3 mitotic index was significantly associated both with the standard mitotic count and with the MIB-1 index. Univariate analyses revealed that all 3 measurements of proliferation were significantly associated with survival. However, the pHH3 mitotic index accounted for a larger proportion of variability in survival than standard mitotic count or MIB-1/Ki-67 labeling index. After adjusting for age, extent of resection, and performance score, the pHH3 mitotic index remained an independent predictor of survival. Thus, pHH3 staining provides a simple and reliable method for quantifying proliferative potential and for the stratification of patients with diffuse astrocytomas into typical grade II and III groups. These results also suggest that pHH3 staining may be a useful method in other neoplasms in which accurate determination of proliferation potential
A high-frequency Doppler feature in the power spectra of simulated GRMHD black hole accretion disks
Wellons, Sarah; Zhu, Yucong; Narayan, Ramesh; McClintock, Jeffrey E.; Psaltis, Dimitrios
Black hole binaries exhibit a wide range of variability phenomena, from large-scale state changes to broadband noise and quasi-periodic oscillations, but the physical nature of much of this variability is poorly understood. We examine the variability properties of three GRMHD simulations of thin accretion disks around black holes of varying spin, producing light curves and power spectra as would be seen by observers. We find that the simulated power spectra show a broad feature at high frequency, which increases in amplitude with the inclination of the observer. We show that this high-frequency feature is a product of the Doppler effect and that its location is a function of the mass and spin of the black hole. This Doppler feature demonstrates that power spectral properties of the accretion disk can be tied to, and potentially used to determine, physical properties of the black hole.
Wavelet Packet Feature Assessment for High-Density Myoelectric Pattern Recognition and Channel Selection toward Stroke Rehabilitation
Wang, Dongqing; Zhang, Xu; Gao, Xiaoping; Chen, Xiang; Zhou, Ping
This study presents wavelet packet feature assessment of neural control information in paretic upper limb muscles of stroke survivors for myoelectric pattern recognition, taking advantage of high-resolution time–frequency representations of surface electromyogram (EMG) signals. On this basis, a novel channel selection method was developed by combining the Fisher's class separability index and the sequential feedforward selection analyses, in order to determine a small number of appropriate EMG channels from original high-density EMG electrode array. The advantages of the wavelet packet features and the channel selection analyses were further illustrated by comparing with previous conventional approaches, in terms of classification performance when identifying 20 functional arm/hand movements implemented by 12 stroke survivors. This study offers a practical approach including paretic EMG feature extraction and channel selection that enables active myoelectric control of multiple degrees of freedom with paretic muscles. All these efforts will facilitate upper limb dexterity restoration and improved stroke rehabilitation. PMID:27917149
COP-coated vesicles are involved in the mitotic fragmentation of Golgi stacks in a cell-free system
Rat liver Golgi stacks fragmented when incubated with mitotic but not interphase cytosol in a process dependent on time, temperature, energy (added in the form of ATP) and cdc2 kinase. The cross-sectional length of Golgi stacks fell in the presence of mitotic cytosol by approximately 50% over 30 min without a corresponding decrease in the number of cisternae in the stack. The loss of membrane from stacked and single cisternae occurred with a half-time of approximately 20 min, and was matched by the appearance of both small (50-100 nm in diameter) and large (100-200 nm in diameter) vesicular profiles. Small vesicular profiles constituted more than 50% of the total membrane after 60 min of incubation and they were shown to be vesicles or very short tubules by serial sectioning. In the presence of GTP gamma S all of the small vesicles were COP-coated and both the extent and the rate at which they formed were sufficient to account for the production of small vesicles during mitotic incubation. The involvement of the COP-mediated budding mechanism was confirmed by immunodepletion of one of the subunits of COP coats (the coatomer) from mitotic cytosol. Vesicles were no longer formed but highly fenestrated networks appeared, an effect reversed by the readdition of purified coatomer. Together these experiments provide strong support for our hypothesis that the observed vesiculation of the Golgi apparatus during mitosis in animal cells is caused by continued budding of COP-coated transport vesicles but an inhibition of their fusion with their target membranes. PMID:8163545
Callous-Unemotional Features, Behavioral Inhibition, and Parenting: Independent Predictors of Aggression in a High-Risk Preschool Sample
ERIC Educational Resources Information Center
Kimonis, Eva R.; Frick, Paul J.; Boris, Neil W.; Smyke, Anna T.; Cornell, Amy H.; Farrell, Jamie M.; Zeanah, Charles H.
A behaviorally-uninhibited temperament, callous-unemotional (CU) features, and harsh parenting have been associated with specific patterns of aggressive behavior in older children and adolescents. We tested the additive and interactive effects of these factors in predicting different types of aggressive behavior in a high-risk preschool sample.…
NAP1 acts with Clb1 to perform mitotic functions and to suppress polar bud growth in budding yeast
NAP1 is a 60-kD protein that interacts specifically with mitotic cyclins in budding yeast and frogs. We have examined the ability of the yeast mitotic cyclin Clb2 to function in cells that lack NAP1. Our results demonstrate that Clb2 is unable to carry out its full range of functions without NAP1, even though Clb2/p34CDC28-associated kinase activity rises to normal levels. In the absence of NAP1, Clb2 is unable to efficiently induce mitotic events, and cells undergo a prolonged delay at the short spindle stage with normal levels of Clb2/p34CDC28 kinase activity. NAP1 is also required for the ability of Clb2 to induce the switch from polar to isotropic bud growth. As a result, polar bud growth continues during mitosis, giving rise to highly elongated cells. Our experiments also suggest that NAP1 is required for the ability of the Clb2/p34CDC28 kinase complex to amplify its own production, and that NAP1 plays a role in regulation of microtubule dynamics during mitosis. Together, these results demonstrate that NAP1 is required for the normal function of the activated Clb2/p34CDC28 kinase complex, and provide a step towards understanding how cyclin- dependent kinase complexes induce specific events during the cell cycle. PMID:7622567
Drosophila Wee1 kinase rescues fission yeast from mitotic catastrophe and phosphorylates Drosophila Cdc2 in vitro.
Campbell, S D; Sprenger, F; Edgar, B A; O'Farrell, P H
Cdc2 kinase activity is required for triggering entry into mitosis in all known eukaryotes. Elaborate mechanisms have evolved for regulating Cdc2 activity so that mitosis occurs in a timely manner, when preparations for its execution are complete. In Schizosaccharomyces pombe, Wee1 and a related Mik1 kinase are Cdc2-inhibitory kinases that are required for preventing premature activation of the mitotic program. To identify Cdc2-inhibitory kinases in Drosophila, we screened for cDNA clones that rescue S. pombe wee1- mik1- mutants from lethal mitotic catastrophe. One of the genes identified in this screen, Drosophila wee1 (Dwee1), encodes a new Wee1 homologue. Dwee1 kinase is closely related to human and Xenopus Wee1 homologues, and can inhibit Cdc2 activity by phosphorylating a critical tyrosine residue. Dwee1 mRNA is maternally provided to embryos, and is zygotically expressed during the postblastoderm divisions of embryogenesis. Expression remains high in the proliferating cells of the central nervous system well after cells in the rest of the embryo have ceased dividing. The loss of zygotically expressed Dwee1 does not lead to mitotic catastrophe during postblastoderm cycles 14 to 16. This result may indicate that maternally provided Dwee1 is sufficient for regulating Cdc2 during embryogenesis, or it may reflect the presence of a redundant Cdc2 inhibitory kinase, as in fission yeast. Images PMID:8573790
Fission Yeast Receptor of Activated C Kinase (RACK1) Ortholog Cpc2 Regulates Mitotic Commitment through Wee1 Kinase*
Núñez, Andrés; Franco, Alejandro; Soto, Teresa; Vicente, Jero; Gacto, Mariano; Cansado, José
In the fission yeast Schizosaccharomyces pombe, Wee1-dependent inhibitory phosphorylation of the highly conserved Cdc2/Cdk1 kinase determines the mitotic onset when cells have reached a defined size. The receptor of activated C kinase (RACK1) is a scaffolding protein strongly conserved among eukaryotes which binds to other proteins to regulate multiple processes in mammalian cells, including the modulation of cell cycle progression during G1/S transition. We have recently described that Cpc2, the fission yeast ortholog to RACK1, controls from the ribosome the activation of MAPK cascades and the cellular defense against oxidative stress by positively regulating the translation of specific genes whose products participate in the above processes. Intriguingly, mutants lacking Cpc2 display an increased cell size at division, suggesting the existence of a specific cell cycle defect at the G2/M transition. In this work we show that protein levels of Wee1 mitotic inhibitor are increased in cells devoid of Cpc2, whereas the levels of Cdr2, a Wee1 inhibitor, are down-regulated in the above mutant. On the contrary, the kinetics of G1/S transition was virtually identical both in control and Cpc2-less strains. Thus, our results suggest that in fission yeast Cpc2/RACK1 positively regulates from the ribosome the mitotic onset by modulating both the protein levels and the activity of Wee1. This novel mechanism of translational control of cell cycle progression might be conserved in higher eukaryotes. PMID:20974849
Formation of coastline features by large-scale instabilities induced by high-angle waves.
Ashton, A; Murray, A B; Arnault, O
Along shore sediment transport that is driven by waves is generally assumed to smooth a coastline. This assumption is valid for small angles between the wave crest lines and the shore, as has been demonstrated in shoreline models. But when the angle between the waves and the shoreline is sufficiently large, small perturbations to a straight shoreline will grow. Here we use a numerical model to investigate the implications of this instability mechanism for large-scale morphology over long timescales. Our simulations show growth of coastline perturbations that interact with each other to produce large-scale features that resemble various kinds of natural landforms, including the capes and cuspate forelands observed along the Carolina coast of southeastern North America. Wind and wave data from this area support our hypothesis that such an instability mechanism could be responsible for the formation of shoreline features at spatial scales up to hundreds of kilometres and temporal scales up to millennia.
Determination of Cell Cycle Stage and Mitotic Exit Through the Quantification of the Protein Levels of Known Mitotic Regulators.
Cepeda-García, Cristina
There are multiple processes that occur at certain points during the cell cycle and that affect later steps. Impairment of such processes could cause delays or even completely abolish cell cycle progression. Therefore, it is extremely helpful in order to determine the potential consequences that interfering on a cellular process imposes on cell cycle progression to be able to precisely characterize the cell cycle stage by using molecular markers. Here, we describe the analysis of the protein levels of known mitotic regulators as molecular markers to monitor the progression of cells through the cell cycle by western blot in synchronized yeast cell cultures.
Microstructural Features Controlling Ductile-to-Brittle Transition Behavior in High-Strength, Martensitic Steel Weld Metals
Development Report Microstructural Features Controlling Ductile-to- Brittle Transition Behavior in High-Strength, Martensitic Steel Weld Metals C 0by...Martensitic Steel Weld Metals PERSONAL AUTHOR(S) .J. DeLoach, Jr. .TYPE OF REPORT 13b TIME COVERED 114 DATE OF REPORT (Year, Month, Day) 1S PAGE COUNT I...if necessary and identify by block number) FIELD GROUP SUB-GROUP High strength steel , Ductile-brittle transition Martensitic Mechanical proper ties
Fiber feature map based landmark initialization for highly deformable DTI registration.
Gupta, Aditya; Toews, Matthew; Janardhana, Ravikiran; Rathi, Yogesh; Gilmore, John; Escolar, Maria; Styner, Martin
This paper presents a novel pipeline for the registration of diffusion tensor images (DTI) with large pathological variations to normal controls based on the use of a novel feature map derived from white matter (WM) fiber tracts. The research presented aims towards an atlas based DTI analysis of subjects with considerable brain pathologies such as tumors or hydrocephalus. In this paper, we propose a novel feature map that is robust against variations in WM fiber tract integrity and use these feature maps to determine a landmark correspondence using a 3D point correspondence algorithm. This correspondence drives a deformation field computed using Gaussian radial basis functions(RBF). This field is employed as an initialization to a standard deformable registration method like demons. We present early preliminary results on the registration of a normal control dataset to a dataset with abnormally enlarged lateral ventricles affected by fatal demyelinating Krabbe disease. The results are analyzed based on a regional tensor matching criterion and a visual assessment of overlap of major WM fiber tracts. While further evaluation and improvements are necessary, the results presented in this paper highlight the potential of our method in handling registration of subjects with severe WM pathology.
On the scaling features of high-latitude geomagnetic field fluctuations during a large geomagnetic storm
NASA Astrophysics Data System (ADS)
De Michelis, Paola; Federica Marcucci, Maria; Consolini, Giuseppe
Recently we have investigated the spatial distribution of the scaling features of short-time scale magnetic field fluctuations using measurements from several ground-based geomagnetic observatories distributed in the northern hemisphere. We have found that the scaling features of fluctuations of the horizontal magnetic field component at time scales below 100 minutes are correlated with the geomagnetic activity level and with changes in the currents flowing in the ionosphere. Here, we present a detailed analysis of the dynamical changes of the magnetic field scaling features as a function of the geomagnetic activity level during the well-known large geomagnetic storm occurred on July, 15, 2000 (the Bastille event). The observed dynamical changes are discussed in relationship with the changes of the overall ionospheric polar convection and potential structure as reconstructed using SuperDARN data. This work is supported by the Italian National Program for Antarctic Research (PNRA) - Research Project 2013/AC3.08 and by the European Community's Seventh Framework Programme ([FP7/2007-2013]) under Grant no. 313038/STORM and
Unconventional Functions of Mitotic Kinases in Kidney Tumorigenesis
Hascoet, Pauline; Chesnel, Franck; Le Goff, Cathy; Le Goff, Xavier; Arlot-Bonnemains, Yannick
Human tumors exhibit a variety of genetic alterations, including point mutations, translocations, gene amplifications and deletions, as well as aneuploid chromosome numbers. For carcinomas, aneuploidy is associated with poor patient outcome for a large variety of tumor types, including breast, colon, and renal cell carcinoma. The Renal cell carcinoma (RCC) is a heterogeneous carcinoma consisting of different histologic types. The clear renal cell carcinoma (ccRCC) is the most common subtype and represents 85% of the RCC. Central to the biology of the ccRCC is the loss of function of the Von Hippel–Lindau gene, but is also associated with genetic instability that could be caused by abrogation of the cell cycle mitotic spindle checkpoint and may involve the Aurora kinases, which regulate centrosome maturation. Aneuploidy can also result from the loss of cell–cell adhesion and apical–basal cell polarity that also may be regulated by the mitotic kinases (polo-like kinase 1, casein kinase 2, doublecortin-like kinase 1, and Aurora kinases). In this review, we describe the "non-mitotic" unconventional functions of these kinases in renal tumorigenesis. PMID:26579493
Inhibition of mitotic-specific histone phophorylation by sodium arsenite
Cobo, J.M.; Valdez, J.G.; Gurley, L.R.
Synchronized cultures of Chinese hamster cells (line CHO) were used to measure the effects of 10{mu}M sodium arsenite on histone phosphorylation. This treatment caused cell proliferation to be temporarily arrested, after which the cells spontaneously resumed cell proliferation in a radiomimetric manner. Immediately following treatment, it was found that sodium arsenite affected only mitotic-specific HI and H3 phosphorylations. Neither interphase, nor mitotic, H2A and H4 phosphorylations were affected, nor was interphase HI Phosphorylation affected. The phosphorylation of HI was inhibited only in mitosis, reducing HI phosphorylation to 38.1% of control levels, which was the level of interphase HI phosphorylation. The phosphorylation of both H3 variants was inhibited in mitosis, the less hydrophobic H3 to 19% and the more hydrophobic H3 to 24% of control levels. These results suggest that sodium arsenite may inhibite cell proliferation by interfering with the cyclin B/p34{sup cdc2} histone kinase activity which is thought to play a key role in regulating the cell cycle. It has been proposed by our laboratory that HI and H3 phosphorylations play a role in restructuring interphase chromatin into metaphase chromosomes. Interference of this process by sodium arsenite may lead to structurally damaged chromosomes resulting in the increased cancer risks known to be produced by arsenic exposure from the environment.
Development of a Computational High-Throughput Tool for the Quantitative Examination of Dose-Dependent Histological Features
Nault, Rance; Colbry, Dirk; Brandenberger, Christina; Harkema, Jack R.; Zacharewski, Timothy R.
High-resolution digitalizing of histology slides facilitates the development of computational alternatives to manual quantitation of features of interest. We developed a MATLAB-based quantitative histological analysis tool (QuHAnT) for the high-throughput assessment of distinguishable histological features. QuHAnT validation was demonstrated by comparison with manual quantitation using liver sections from mice orally gavaged with sesame oil vehicle or 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD; 0.001–30 µg/kg) every 4 days for 28 days, which elicits hepatic steatosis with mild fibrosis. A quality control module of QuHAnT reduced the number of quantifiable Oil Red O (ORO)-stained images from 3,123 to 2,756. Increased ORO staining was measured at 10 and 30 µg/kg TCDD with a high correlation between manual and computational volume densities (Vv), although the dynamic range of QuHAnT was 10-fold greater. Additionally, QuHAnT determined the size of each ORO vacuole, which could not be accurately quantitated by visual examination or manual point counting. PicroSirius Red quantitation demonstrated superior collagen deposition detection due to the ability to consider all images within each section. QuHAnT dramatically reduced analysis time and facilitated the comprehensive assessment of features improving accuracy and sensitivity and represents a complementary tool for tissue/cellular features that are difficult and tedious to assess via subjective or semiquantitative methods. PMID:25274660
Cascaded ensemble of convolutional neural networks and handcrafted features for mitosis detection
NASA Astrophysics Data System (ADS)
Wang, Haibo; Cruz-Roa, Angel; Basavanhally, Ajay; Gilmore, Hannah; Shih, Natalie; Feldman, Mike; Tomaszewski, John; Gonzalez, Fabio; Madabhushi, Anant
Breast cancer (BCa) grading plays an important role in predicting disease aggressiveness and patient outcome. A key component of BCa grade is mitotic count, which involves quantifying the number of cells in the process of dividing (i.e. undergoing mitosis) at a specific point in time. Currently mitosis counting is done manually by a pathologist looking at multiple high power fields on a glass slide under a microscope, an extremely laborious and time consuming process. The development of computerized systems for automated detection of mitotic nuclei, while highly desirable, is confounded by the highly variable shape and appearance of mitoses. Existing methods use either handcrafted features that capture certain morphological, statistical or textural attributes of mitoses or features learned with convolutional neural networks (CNN). While handcrafted features are inspired by the domain and the particular application, the data-driven CNN models tend to be domain agnostic and attempt to learn additional feature bases that cannot be represented through any of the handcrafted features. On the other hand, CNN is computationally more complex and needs a large number of labeled training instances. Since handcrafted features attempt to model domain pertinent attributes and CNN approaches are largely unsupervised feature generation methods, there is an appeal to attempting to combine these two distinct classes of feature generation strategies to create an integrated set of attributes that can potentially outperform either class of feature extraction strategies individually. In this paper, we present a cascaded approach for mitosis detection that intelligently combines a CNN model and handcrafted features (morphology, color and texture features). By employing a light CNN model, the proposed approach is far less demanding computationally, and the cascaded strategy of combining handcrafted features and CNN-derived features enables the possibility of maximizing performance by
Neuroblastoma cells depend on HDAC11 for mitotic cell cycle progression and survival.
Thole, Theresa M; Lodrini, Marco; Fabian, Johannes; Wuenschel, Jasmin; Pfeil, Sebastian; Hielscher, Thomas; Kopp-Schneider, Annette; Heinicke, Ulrike; Fulda, Simone; Witt, Olaf; Eggert, Angelika; Fischer, Matthias; Deubzer, Hedwig E
The number of long-term survivors of high-risk neuroblastoma remains discouraging, with 10-year survival as low as 20%, despite decades of considerable international efforts to improve outcome. Major obstacles remain and include managing resistance to induction therapy, which causes tumor progression and early death in high-risk patients, and managing chemotherapy-resistant relapses, which can occur years after the initial diagnosis. Identifying and validating novel therapeutic targets is essential to improve treatment. Delineating and deciphering specific functions of single histone deacetylases in neuroblastoma may support development of targeted acetylome-modifying therapeutics for patients with molecularly defined high-risk neuroblastoma profiles. We show here that HDAC11 depletion in MYCN-driven neuroblastoma cell lines strongly induces cell death, mostly mediated by apoptotic programs. Genes necessary for mitotic cell cycle progression and cell division were most prominently enriched in at least two of three time points in whole-genome expression data combined from two cell systems, and all nine genes in these functional categories were strongly repressed, including CENPA, KIF14, KIF23 and RACGAP1. Enforced expression of one selected candidate, RACGAP1, partially rescued the induction of apoptosis caused by HDAC11 depletion. High-level expression of all nine genes in primary neuroblastomas significantly correlated with unfavorable overall and event-free survival in patients, suggesting a role in mediating the more aggressive biological and clinical phenotype of these tumors. Our study identified a group of cell cycle-promoting genes regulated by HDAC11, being both predictors of unfavorable patient outcome and essential for tumor cell viability. The data indicate a significant role of HDAC11 for mitotic cell cycle progression and survival of MYCN-amplified neuroblastoma cells, and suggests that HDAC11 could be a valuable drug target.
Validate Mitotic Checkpoint and Kinetochore Motor Proteins in Breast Cancer Cells as Targets for the Development of Novel Anti-Mitotic Drugs
which chromosomal instability, aneuploidy, and increased tumorigenesis are prominent hallmarks. These include ataxia-telangiectasia, xeroderma ... pigmentosum , Nijmegen breakage syndromes, Bloom's syndrome, and Werner's syndrome, (Modesti and Kanaar, 2001; Thompson and Schild, 2002). Defects in mitotic
Spatial correlation of high density EMG signals provides features robust to electrode number and shift in pattern recognition for myocontrol.
Stango, Antonietta; Negro, Francesco; Farina, Dario
Research on pattern recognition for myoelectric control has usually focused on a small number of electromyography (EMG) channels because of better clinical acceptability and low computational load with respect to multi-channel EMG. However, recently, high density (HD) EMG technology has substantially improved, also in practical usability, and can thus be applied in myocontrol. HD EMG provides several closely spaced recordings in multiple locations over the skin surface. This study considered the use of HD EMG for controlling upper limb prostheses, based on pattern recognition. In general, robustness and reliability of classical pattern recognition systems are influenced by electrode shift in dons and doff, and by the presence of malfunctioning channels. The aim of this study is to propose a new approach to attenuate these issues. The HD EMG grid of electrodes is an ensemble of sensors that records data spatially correlated. The experimental variogram, which is a measure of the degree of spatial correlation, was used as feature for classification, contrary to previous approaches that are based on temporal or frequency features. The classification based on the variogram was tested on seven able-bodied subjects and one subject with amputation, for the classification of nine and seven classes, respectively. The performance of the proposed approach was comparable with the classic methods based on time-domain and autoregressive features (average classification accuracy over all methods ∼ 95% for nine classes). However, the new spatial features demonstrated lower sensitivity to electrode shift ( ± 1 cm) with respect to the classic features . When even just one channel was noisy, the classification accuracy dropped by ∼ 10% for all methods. However, the new method could be applied without any retraining to a subset of high-quality channels whereas the classic methods require retraining when some channels are omitted. In conclusion, the new spatial feature space
The Luminous Polycyclic Aromatic Hydrocarbon Emission Features: Applications to High Redshift Galaxies and Active Galactic Nuclei
NASA Astrophysics Data System (ADS)
Shipley, Heath V.
For decades, significant work has been applied to calibrating emission from the ultra-violet, nebular emission lines, far-infrared, X-ray and radio as tracers of the star-formation rate (SFR) in distant galaxies. Understanding the exact rate of star-formation and how it evolves with time and galaxy mass has deep implications for how galaxies form. The co-evolution of star-formation and supermassive black hole (SMBH) accretion is one of the key problems in galaxy formation theory. But, many of these SFR indicators are influenced by SMBH accretion in galaxies and result in unreliable SFRs. Utilizing the luminous polycyclic aromatic hydrocarbon (PAH) emission features, I provide a new robust SFR calibration using the luminosity emitted from the PAHs at 6.2μm, 7.7μm and 11.3μm to solve this. The PAH features emit strongly in the mid-infrared (mid-IR; 5-25μm) mitigating dust extinction, containing on average 5-10% of the total IR luminosity in galaxies. I use a sample of 105 star-forming galaxies covering a range of total IR luminosity, LIR = L(8-1000μm) = 109 - 1012 L⊙ and redshift 0 < z < 0.4, with mid-IR spectroscopy from the Spitzer Infrared Spectrograph (IRS), and data covering other SFR indicators (Hα emission and rest-frame 24μm continuum emission). The PAH luminosity correlates linearly with the SFR as measured by the Hα luminosity (corrected for attenuation using the mono-chromatic rest-frame 24μm emission), with a tight scatter of <0.15 dex. The scatter is comparable to that between SFRs derived from the Paα and dust-corrected Hα emission lines. We present a case study in advance of JWST, which will be capable of measuring SFRs (from 8μm rest-frame photometry, i.e. PAHs) in distant galaxies (z ≤ 2) with JWST/MIRI to SFRs as low as ~10 M⊙yr-1, because the PAH features are so bright. We use Spitzer/IRS observations of PAH features in lensed star-forming galaxies at 1 < z < 3 to demonstrate the utility of the PAHs to derive SFRs that agree with
Timely Endocytosis of Cytokinetic Enzymes Prevents Premature Spindle Breakage during Mitotic Exit
Onishi, Masayuki; Yeong, Foong May
Cytokinesis requires the spatio-temporal coordination of membrane deposition and primary septum (PS) formation at the division site to drive acto-myosin ring (AMR) constriction. It has been demonstrated that AMR constriction invariably occurs only after the mitotic spindle disassembly. It has also been established that Chitin Synthase II (Chs2p) neck localization precedes mitotic spindle disassembly during mitotic exit. As AMR constriction depends upon PS formation, the question arises as to how chitin deposition is regulated so as to prevent premature AMR constriction and mitotic spindle breakage. In this study, we propose that cells regulate the coordination between spindle disassembly and AMR constriction via timely endocytosis of cytokinetic enzymes, Chs2p, Chs3p, and Fks1p. Inhibition of endocytosis leads to over accumulation of cytokinetic enzymes during mitotic exit, which accelerates the constriction of the AMR, and causes spindle breakage that eventually could contribute to monopolar spindle formation in the subsequent round of cell division. Intriguingly, the mitotic spindle breakage observed in endocytosis mutants can be rescued either by deleting or inhibiting the activities of, CHS2, CHS3 and FKS1, which are involved in septum formation. The findings from our study highlight the importance of timely endocytosis of cytokinetic enzymes at the division site in safeguarding mitotic spindle integrity during mitotic exit. PMID:27447488
Asynchronous Event-Based Multikernel Algorithm for High-Speed Visual Features Tracking.
Lagorce, Xavier; Meyer, Cédric; Ieng, Sio-Hoi; Filliat, David; Benosman, Ryad
This paper presents a number of new methods for visual tracking using the output of an event-based asynchronous neuromorphic dynamic vision sensor. It allows the tracking of multiple visual features in real time, achieving an update rate of several hundred kilohertz on a standard desktop PC. The approach has been specially adapted to take advantage of the event-driven properties of these sensors by combining both spatial and temporal correlations of events in an asynchronous iterative framework. Various kernels, such as Gaussian, Gabor, combinations of Gabor functions, and arbitrary user-defined kernels, are used to track features from incoming events. The trackers described in this paper are capable of handling variations in position, scale, and orientation through the use of multiple pools of trackers. This approach avoids the N(2) operations per event associated with conventional kernel-based convolution operations with N × N kernels. The tracking performance was evaluated experimentally for each type of kernel in order to demonstrate the robustness of the proposed solution.
Brain Tumour Segmentation based on Extremely Randomized Forest with high-level features.
Pinto, Adriano; Pereira, Sergio; Correia, Higino; Oliveira, J; Rasteiro, Deolinda M L D; Silva, Carlos A
Gliomas are among the most common and aggressive brain tumours. Segmentation of these tumours is important for surgery and treatment planning, but also for follow-up evaluations. However, it is a difficult task, given that its size and locations are variable, and the delineation of all tumour tissue is not trivial, even with all the different modalities of the Magnetic Resonance Imaging (MRI). We propose a discriminative and fully automatic method for the segmentation of gliomas, using appearance- and context-based features to feed an Extremely Randomized Forest (Extra-Trees). Some of these features are computed over a non-linear transformation of the image. The proposed method was evaluated using the publicly available Challenge database from BraTS 2013, having obtained a Dice score of 0.83, 0.78 and 0.73 for the complete tumour, and the core and the enhanced regions, respectively. Our results are competitive, when compared against other results reported using the same database.
Mitosis detection in breast cancer pathology images by combining handcrafted and convolutional neural network features
Wang, Haibo; Cruz-Roa, Angel; Basavanhally, Ajay; Gilmore, Hannah; Shih, Natalie; Feldman, Mike; Tomaszewski, John; Gonzalez, Fabio; Madabhushi, Anant
Abstract. Breast cancer (BCa) grading plays an important role in predicting disease aggressiveness and patient outcome. A key component of BCa grade is the mitotic count, which involves quantifying the number of cells in the process of dividing (i.e., undergoing mitosis) at a specific point in time. Currently, mitosis counting is done manually by a pathologist looking at multiple high power fields (HPFs) on a glass slide under a microscope, an extremely laborious and time consuming process. The development of computerized systems for automated detection of mitotic nuclei, while highly desirable, is confounded by the highly variable shape and appearance of mitoses. Existing methods use either handcrafted features that capture certain morphological, statistical, or textural attributes of mitoses or features learned with convolutional neural networks (CNN). Although handcrafted features are inspired by the domain and the particular application, the data-driven CNN models tend to be domain agnostic and attempt to learn additional feature bases that cannot be represented through any of the handcrafted features. On the other hand, CNN is computationally more complex and needs a large number of labeled training instances. Since handcrafted features attempt to model domain pertinent attributes and CNN approaches are largely supervised feature generation methods, there is an appeal in attempting to combine these two distinct classes of feature generation strategies to create an integrated set of attributes that can potentially outperform either class of feature extraction strategies individually. We present a cascaded approach for mitosis detection that intelligently combines a CNN model and handcrafted features (morphology, color, and texture features). By employing a light CNN model, the proposed approach is far less demanding computationally, and the cascaded strategy of combining handcrafted features and CNN-derived features enables the possibility of maximizing the
Reduced mitotic activity at the periphery of human embryonic stem cell colonies cultured in vitro with mitotically-inactivated murine embryonic fibroblast feeder cells.
Heng, Boon Chin; Cao, Tong; Liu, Hua; Rufaihah, Abdul Jalil
This study attempted to investigate whether different levels of mitotic activity exist within different physical regions of a human embryonic stem (hES) cell colony. Incorporation of 5-bromo-2-deoxyuridine (BrdU) within newly-synthesized DNA, followed by immunocytochemical staining was used as a means of detecting mitotically-active cells within hES colonies. The results showed rather surprisingly that the highest levels of mitotic activity are primarily concentrated within the central regions of hES colonies, whereas the peripheral regions exhibited reduced levels of cellular proliferation. Two hypothetical mechanisms are therefore proposed for hES colony growth and expansion. Firstly, it is envisaged that the less mitotically-active hES cells at the periphery of the colony are continually migrating outwards, thereby providing space for newly-divided daughter cells within the more mitotically-active central region of the hES colony. Secondly, it is proposed that the newly-divided hES cells within the central region of the colony somehow migrate to the outer periphery. This could possibly explain why the periphery of hES colonies are less mitotically-active, since there would obviously be an extended time-lag before newly-divided daughter cells are ready again for the next cell division. Further investigations need to be carried out to characterize the atypical mechanisms by which hES colonies grow and expand in size.
Gene-specific factors determine mitotic expression and bookmarking via alternate regulatory elements
Arampatzi, Panagiota; Gialitakis, Manolis; Makatounakis, Takis; Papamatheakis, Joseph
Transcriptional silencing during mitosis is caused by inactivation of critical transcriptional regulators and/or chromatin condensation. Inheritance of gene expression patterns through cell division involves various bookmarking mechanisms. In this report, we have examined the mitotic and post-mitotic expression of the DRA major histocompatibility class II (MHCII) gene in different cell types. During mitosis the constitutively MHCII-expressing B lymphoblastoid cells showed sustained occupancy of the proximal promoter by the cognate enhanceosome and general transcription factors. In contrast, although mitotic epithelial cells were depleted of these proteins irrespectively of their MHCII transcriptional activity, a distal enhancer selectively recruited the PP2A phosphatase via NFY and maintained chromatin accessibility. Based on our data, we propose a novel chromatin anti-condensation role for this element in mitotic bookmarking and timing of post-mitotic transcriptional reactivation. PMID:23303784
Temporal and compartment-specific signals coordinate mitotic exit with spindle position
Caydasi, Ayse Koca; Khmelinskii, Anton; Duenas-Sanchez, Rafael; Kurtulmus, Bahtiyar; Knop, Michael; Pereira, Gislene
The spatiotemporal control of mitotic exit is crucial for faithful chromosome segregation during mitosis. In budding yeast, the mitotic exit network (MEN) drives cells out of mitosis, whereas the spindle position checkpoint (SPOC) blocks MEN activity when the anaphase spindle is mispositioned. How the SPOC operates at a molecular level remains unclear. Here, we report novel insights into how mitotic signalling pathways orchestrate chromosome segregation in time and space. We establish that the key function of the central SPOC kinase, Kin4, is to counterbalance MEN activation by the cdc fourteen early anaphase release (FEAR) network in the mother cell compartment. Remarkably, Kin4 becomes dispensable for SPOC function in the absence of FEAR. Cells lacking both FEAR and Kin4 show that FEAR contributes to mitotic exit through regulation of the SPOC component Bfa1 and the MEN kinase Cdc15. Furthermore, we uncover controls that specifically promote mitotic exit in the daughter cell compartment. PMID:28117323
Microtubule organization within mitotic spindles revealed by serial block face scanning EM and image analysis.
Nixon, Faye M; Honnor, Thomas R; Clarke, Nicholas I; Starling, Georgina P; Beckett, Alison J; Johansen, Adam M; Brettschneider, Julia A; Prior, Ian A; Royle, Stephen J
Serial block face scanning electron microscopy (SBF-SEM) is a powerful method to analyze cells in 3D. Here, working at the resolution limit of the method, we describe a correlative light-SBF-SEM workflow to resolve microtubules of the mitotic spindle in human cells. We present four examples of uses for this workflow which are not practical by light microscopy and/or transmission electron microscopy. First, distinguishing closely associated microtubules within K-fibers; second, resolving bridging fibers in the mitotic spindle; third, visualizing membranes in mitotic cells, relative to the spindle apparatus; fourth, volumetric analysis of kinetochores. Our workflow also includes new computational tools for exploring the spatial arrangement of MTs within the mitotic spindle. We use these tools to show that microtubule order in mitotic spindles is sensitive to the level of TACC3 on the spindle.
Temporal and compartment-specific signals coordinate mitotic exit with spindle position.
Caydasi, Ayse Koca; Khmelinskii, Anton; Duenas-Sanchez, Rafael; Kurtulmus, Bahtiyar; Knop, Michael; Pereira, Gislene
The spatiotemporal control of mitotic exit is crucial for faithful chromosome segregation during mitosis. In budding yeast, the mitotic exit network (MEN) drives cells out of mitosis, whereas the spindle position checkpoint (SPOC) blocks MEN activity when the anaphase spindle is mispositioned. How the SPOC operates at a molecular level remains unclear. Here, we report novel insights into how mitotic signalling pathways orchestrate chromosome segregation in time and space. We establish that the key function of the central SPOC kinase, Kin4, is to counterbalance MEN activation by the cdc fourteen early anaphase release (FEAR) network in the mother cell compartment. Remarkably, Kin4 becomes dispensable for SPOC function in the absence of FEAR. Cells lacking both FEAR and Kin4 show that FEAR contributes to mitotic exit through regulation of the SPOC component Bfa1 and the MEN kinase Cdc15. Furthermore, we uncover controls that specifically promote mitotic exit in the daughter cell compartment.
Infradian biorhythms of mitotic activity esophageal epithelium in male Wistar rats.
Diatroptov, M E; Makarova, O V
Infradian rhythms of esophageal epithelium mitotic activity were studied in male Wistar rats of two age groups: 35-45 days (prepubertal) and 3-4 months (adults). Studies of the time course of esophageal epithelium mitotic indexes in adult males showed 4- and 12-day biorhythms, while prepubertal rats exhibited only 4-day infradian biorhythms of this parameter. Studies of the mitotic activity over long periods (3 years) showed 4.058- and 12.175-day periodicity of infradian biorhythms for this parameter, presumably due to external exposures synchronizing the biorhythms. Studies of the mean daily values of the Bz component of interplanetary magnetic field during the period of our research (2012-2013) showed rhythmicities analogous to changes in the mitotic activity of the epithelium. The minimum mitotic indexes were detected on the days of the most pronounced negative values of the interplanetary magnetic field Bz component.
Mice produced by mitotic reprogramming of sperm injected into haploid parthenogenotes
Suzuki, Toru; Asami, Maki; Hoffmann, Martin; Lu, Xin; Gužvić, Miodrag; Klein, Christoph A.; Perry, Anthony C. F.
Sperm are highly differentiated and the activities that reprogram them for embryonic development during fertilization have historically been considered unique to the oocyte. We here challenge this view and demonstrate that mouse embryos in the mitotic cell cycle can also directly reprogram sperm for full-term development. Developmentally incompetent haploid embryos (parthenogenotes) injected with sperm developed to produce healthy offspring at up to 24% of control rates, depending when in the embryonic cell cycle injection took place. This implies that most of the first embryonic cell cycle can be bypassed in sperm genome reprogramming for full development. Remodelling of histones and genomic 5′-methylcytosine and 5′-hydroxymethylcytosine following embryo injection were distinct from remodelling in fertilization and the resulting 2-cell embryos consistently possessed abnormal transcriptomes. These studies demonstrate plasticity in the reprogramming of terminally differentiated sperm nuclei and suggest that different epigenetic pathways or kinetics can establish totipotency. PMID:27623537
Chromosome and mitotic spindle dynamics in fission yeast kinesin-8 mutants
NASA Astrophysics Data System (ADS)
Crapo, Ammon M.; Gergley, Zachary R.; McIntosh, J. Richard; Betterton, M. D.
Fission yeast proteins Klp5p and Klp6p are plus-end directed motors of the kinesin-8 family which promote microtubule (MT) depolymerization and also affect chromosome segregation, but the mechanism of these activities is not well understood. Using live-cell time-lapse fluorescence microscopy of fission yeast wild-type (WT) and klp5/6 mutant strains, we quantify and compare the dynamics of kinetochore motion and mitotic spindle length in 3D. In WT cells, the spindle, once formed, remains a consistent size and chromosomes are correctly organized and segregated. In kinesin-8 mutants, spindles undergo large length fluctuations of several microns. Kinetochore motions are also highly fluctuating, with kinetochores frequently moving away from the spindle rather than toward it. We observe transient pushing of chromosomes away from the spindle by as much as 10 microns in distance.
Toucan protein is essential for the assembly of syncytial mitotic spindles in Drosophila melanogaster.
Debec, A; Grammont, M; Berson, G; Dastugue, B; Sullivan, W; Couderc, J L
The toc gene of Drosophila melanogaster encodes a 235-kD polypeptide with a coiled-coil domain, which is highly expressed during oogenesis (Grammont et al., 1997, 2000). We now report the localization of the Toucan protein during early embryonic development. The Toucan protein is present only during the syncytial stages and is associated with the nuclear envelope and the cytoskeletal structures of the syncytial embryo. In anaphase A, Toucan is concentrated at the spindle poles near the minus end of microtubules. This microtubule association is very dynamic during the nuclear cell cycle. Mutant embryos lacking the Toucan protein are blocked in a metaphase-like state. They display abnormal and nonfunctional spindles, characterized by broad poles, detachment of the centrosomes, and failure of migration of the chromosomes. These results strongly suggest that Toucan represents a factor essential for the assembly and the function of the syncytial mitotic spindles.
Machine Learning Approaches to Classification of Seafloor Features from High Resolution Sonar Data
NASA Astrophysics Data System (ADS)
Smith, D. G.; Ed, L.; Sofge, D.; Elmore, P. A.; Petry, F.
Navigation charts provide topographic maps of the seafloor created from swaths of sonar data. Converting sonar data to a topographic map is a manual, labor-intensive process that can be greatly assisted by contextual information obtained from automated classification of geomorphological structures. Finding structures such as seamounts can be challenging, as there are no established rules that can be used for decision-making. Often times, it is a determination that is made by human expertise. A variety of feature metrics may be useful for this task and we use a large number of metrics relevant to the task of finding seamounts. We demonstrate this ability in locating seamounts by two related machine learning techniques. As well as achieving good accuracy in classification, the human-understandable set of metrics that are most important for the results are discussed.
Special features of high-speed interaction of supercavitating solids in water
NASA Astrophysics Data System (ADS)
Ishchenko, Aleksandr; Akinshin, Ruslan; Afanas'eva, Svetlana; Borisenkov, Igor; Burkin, Viktor; Diachkovskii, Aleksei; Korolkov, Leonid; Moiseev, Dmitrii; Khabibullin, Marat
Special features of material behavior of a supercavitating projectile are investigated at various initial velocities of entering water on the basis of the developed stress-strain state model with possibility of destruction of solids when moving in water and interacting with various underwater barriers with the use of consistent methodological approach of mechanics of continuous media. The calculation-experimental method was used to study the modes of motion of supercavitating projectiles at sub- and supersonic velocities in water medium after acceleration in the barrelled accelerator, as well as their interaction with barriers. Issues of stabilization of the supercavitating projectile on the initial flight path in water were studied. Microphotographs of state of solids made of various materials, before and after interaction with water, at subsonic and supersonic velocities were presented. Supersonic velocity of the supercavitating projectile motion in water of 1590 m/s was recorded.
Special features of high-speed interaction of supercavitating solids in water
Ishchenko, Aleksandr Afanas'eva, Svetlana Burkin, Viktor Diachkovskii, Aleksei Korolkov, Leonid Moiseev, Dmitrii; Khabibullin, Marat; Akinshin, Ruslan Borisenkov, Igor
Special features of material behavior of a supercavitating projectile are investigated at various initial velocities of entering water on the basis of the developed stress-strain state model with possibility of destruction of solids when moving in water and interacting with various underwater barriers with the use of consistent methodological approach of mechanics of continuous media. The calculation-experimental method was used to study the modes of motion of supercavitating projectiles at sub- and supersonic velocities in water medium after acceleration in the barrelled accelerator, as well as their interaction with barriers. Issues of stabilization of the supercavitating projectile on the initial flight path in water were studied. Microphotographs of state of solids made of various materials, before and after interaction with water, at subsonic and supersonic velocities were presented. Supersonic velocity of the supercavitating projectile motion in water of 1590 m/s was recorded.
Acrylamide effects on kinesin-related proteins of the mitotic/meiotic spindle
Sickles, Dale W. . E-mail: firstname.lastname@example.com; Sperry, Ann O. . E-mail: firstname.lastname@example.com; Testino, Angie; Friedman, Marvin
The microtubule (MT) motor protein kinesin is a vital component of cells and organs expressing acrylamide (ACR) toxicity. As a mechanism of its potential carcinogenicity, we determined whether kinesins involved in cell division are inhibited by ACR similar to neuronal kinesin [Sickles, D.W., Brady, S.T., Testino, A.R., Friedman, M.A., and Wrenn, R.A. (1996). Direct effect of the neurotoxicant acrylamide on kinesin-based microtubule motility. Journal of Neuroscience Research 46, 7-17.] Kinesin-related genes were isolated from rat testes [Navolanic, P.M., and Sperry, A.O. (2000). Identification of isoforms of a mitotic motor in mammalian spermatogenesis. Biology of Reproduction 62, 1360-1369.], their kinesin-like proteins expressed in bacteria using recombinant DNA techniques and the effects of ACR, glycidamide (GLY) and propionamide (a non-neurotoxic metabolite) on the function of two of the identified kinesin motors were tested. KIFC5A MT bundling activity, required for mitotic spindle formation, was measured in an MT-binding assay. Both ACR and GLY caused a similar concentration-dependent reduction in the binding of MT; concentrations of 100 {mu}M ACR or GLY reduced its activity by 60%. KRP2 MT disassembling activity was assayed using the quantity of tubulin disassembled from taxol-stabilized MT. Both ACR and GLY inhibited KRP2-induced MT disassembly. GLY was substantially more potent; significant reductions of 60% were achieved by 500 {mu}M, a comparable inhibition by ACR required a 5 mM concentration. Propionamide had no significant effect on either kinesin, except KRP2 at 10 mM. This is the first report of ACR inhibition of a mitotic/meiotic motor protein. ACR (or GLY) inhibition of kinesin may be an alternative mechanism to DNA adduction in the production of cell division defects and potential carcinogenicity. We conclude that ACR may act on multiple kinesin family members and produce toxicities in organs highly dependent on microtubule-based functions.
Okadaic acid induced cyclin B1 expression and mitotic catastrophe in rat cortex.
Chen, Bo; Cheng, Min; Hong, Dao-Jun; Sun, Feng-Yan; Zhu, Cui-Qing
Accumulating evidence indicates that the aberrant re-entry of post-mitotic neurons into the G2/M phase of cell cycle and the resulting mitotic catastrophe may contribute to the pathogenesis of Alzheimer's disease. However, the cellular event that drives the differentiated neurons to abnormally enter G2/M phase remains elusive. Similarly, whether mitotic catastrophe is indeed one of the death pathways for differentiated neurons is not clear. Previous studies revealed that okadaic acid (OA), a phosphatase inhibitor that induces AD like pathological changes, evokes mitotic changes in neuroblastoma cells. In this study, we examined the in vivo effects of OA on cyclin B1 expression, the induction of mitosis, and subsequent mitotic catastrophe. We found that cyclin B1 expression in adult neurons was significantly increased after injecting OA into rat frontal cortex, which also increased tau protein phosphorylation. Interestingly, cyclin B1 and phosphorylated tau were well co-localized around the OA injection site, but were only partially co-localized in other brain regions. Staining with toluidine blue, Giemsa dye or propidium iodide revealed typical mitotic and mitotic catastrophe-like morphological changes with irregular arrangement of condensed chromatin and chromosome fibers in a few cells. Furthermore, the strong cyclin B1 staining in these cells suggests that cyclin B1 promoted G2 to M phase transition is required for the mitotic catastrophe. The detection of neuron-specific enolase in a portion of these cells demonstrated that at least part them are neuron. All together, our results suggest that the disturbance of the protein kinase-phosphatase system caused by OA is sufficient to induce neuronal cyclin B1 expression, force neurons into the mitotic phase of cell cycle, and cause mitotic catastrophe.
Mitotic rate in melanoma: prognostic value of immunostaining and computer-assisted image analysis.
Hale, Christopher S; Qian, Meng; Ma, Michelle W; Scanlon, Patrick; Berman, Russell S; Shapiro, Richard L; Pavlick, Anna C; Shao, Yongzhao; Polsky, David; Osman, Iman; Darvishian, Farbod
The prognostic value of mitotic rate in melanoma is increasingly recognized, particularly in thin melanoma in which the presence or absence of a single mitosis/mm can change staging from T1a to T1b. Still, accurate mitotic rate calculation (mitoses/mm) on hematoxylin and eosin (H&E)-stained sections can be challenging. Antimonoclonal mitotic protein-2 (MPM-2) and antiphosphohistone-H3 (PHH3) are 2 antibodies reported to be more mitosis-specific than other markers of proliferation such as Ki-67. We used light microscopy and computer-assisted image analysis software to quantify MPM-2 and PHH3 staining in melanoma. We then compared mitotic rates by each method with conventional H&E-based mitotic rate for correlation with clinical outcomes. Our study included primary tissues from 190 nonconsecutive cutaneous melanoma patients who were prospectively enrolled at New York University Langone Medical Center with information on age, gender, and primary tumor characteristics. The mitotic rate was quantified manually by light microscopy of corresponding H&E-stained, MPM-2-stained, and PHH3-stained sections. Computer-assisted image analysis was then used to quantify immunolabeled mitoses on the previously examined PHH3 and MPM-2 slides. We then analyzed the association between mitotic rate and both progression-free and melanoma-specific survival. Univariate analysis of PHH3 found significant correlation between increased PHH3 mitotic rate and decreased progression-free survival (P=0.04). Computer-assisted image analysis enhanced the correlation of PHH3 mitotic rate with progression-free survival (P=0.02). Regardless of the detection method, neither MPM-2 nor PHH3 offered significant advantage over conventional H&E determination of mitotic rate.
High-resolution multibeam mapping and submersible surveys of topographic features in the northwestern Gulf of Mexico
Hickerson, E.L.; Schmahl, G.P.; Weaver, D.C.; Gardner, J.V.
The Flower Garden Banks National Marine Sanctuary (FGBNMS) and the USGS Pacific Seafloor Mapping Project mapped about 2000 km2 of the northwestern Gulf of Mexico continental shelf during June 2002, using a Kongsberg Simrad EM1000 multibeam echosounder. Mapping focused on select topographic highs thave hae been idetnnfied as biological features warranting protection from oil and gas activities by the Minerals Management Service (MMS). The base maps will be used for all future ROV and submersible missions.
Very high resolution Earth observation features for monitoring plant and animal community structure across multiple spatial scales in protected areas
NASA Astrophysics Data System (ADS)
Mairota, Paola; Cafarelli, Barbara; Labadessa, Rocco; Lovergine, Francesco; Tarantino, Cristina; Lucas, Richard M.; Nagendra, Harini; Didham, Raphael K.
Monitoring the status and future trends in biodiversity can be prohibitively expensive using ground-based surveys. Consequently, significant effort is being invested in the use of satellite remote sensing to represent aspects of the proximate mechanisms (e.g., resource availability) that can be related to biodiversity surrogates (BS) such as species community descriptors. We explored the potential of very high resolution (VHR) satellite Earth observation (EO) features as proxies for habitat structural attributes that influence spatial variation in habitat quality and biodiversity change. In a semi-natural grassland mosaic of conservation concern in southern Italy, we employed a hierarchical nested sampling strategy to collect field and VHR-EO data across three spatial extent levels (landscape, patch and plot). Species incidence and abundance data were collected at the plot level for plant, insect and bird functional groups. Spectral and textural VHR-EO image features were derived from a Worldview-2 image. Three window sizes (grains) were tested for analysis and computation of textural features, guided by the perception limits of different organisms. The modelled relationships between VHR-EO features and BS responses differed across scales, suggesting that landscape, patch and plot levels are respectively most appropriate when dealing with birds, plants and insects. This research demonstrates the potential of VHR-EO for biodiversity mapping and habitat modelling, and highlights the importance of identifying the appropriate scale of analysis for specific taxonomic groups of interest. Further, textural features are important in the modelling of functional group-specific indices which represent BS in high conservation value habitat types, and provide a more direct link to species interaction networks and ecosystem functioning, than provided by traditional taxonomic diversity indices.
Regulation of mitotic spindle orientation during epidermal stratification.
Xie, Wei; Zhou, Jun
The epidermis is a stratified epithelium that serves as a barrier to infection from environmental pathogens and prevents water loss. Epidermal stratification is tightly controlled during embryogenesis. Progenitor cells in the developing epidermis undergo both symmetric and asymmetric cell divisions to balance the growth of the skin surface area against the generation of differentiated cell layers. Therefore, understanding the relationship between oriented divisions of progenitor cells and the development and stratification of the epidermis is of paramount importance in the field of skin biology and pathology. We provide here an integrated view of recent studies implicating that improper orientation of the mitotic spindle contributes to disorders associated with abnormal epidermal stratification and suggesting that spindle orientation could serve as a potential therapeutic target in skin diseases.
Mitotic wavefronts mediated by mechanical signaling in early Drosophila embryos
NASA Astrophysics Data System (ADS)
Kang, Louis; Idema, Timon; Liu, Andrea; Lubensky, Tom
Mitosis in the early Drosophila embryo demonstrates spatial and temporal correlations in the form of wavefronts that travel across the embryo in each cell cycle. This coordinated phenomenon requires a signaling mechanism, which we suggest is mechanical in origin. We have constructed a theoretical model that supports nonlinear wavefront propagation in a mechanically-excitable medium. Previously, we have shown that this model captures quantitatively the wavefront speed as it varies with cell cycle number, for reasonable values of the elastic moduli and damping coefficient of the medium. Now we show that our model also captures the displacements of cell nuclei in the embryo in response to the traveling wavefront. This new result further supports that mechanical signaling may play an important role in mediating mitotic wavefronts.
Aurora A's Functions During Mitotic Exit: The Guess Who Game.
Reboutier, David; Benaud, Christelle; Prigent, Claude
Until recently, the knowledge of Aurora A kinase functions during mitosis was limited to pre-metaphase events, particularly centrosome maturation, G2/M transition, and mitotic spindle assembly. However, an involvement of Aurora A in post-metaphase events was also suspected, but not clearly demonstrated due to the technical difficulty to perform the appropriate experiments. Recent developments of both an analog-specific version of Aurora A and small molecule inhibitors have led to the first demonstration that Aurora A is required for the early steps of cytokinesis. As in pre-metaphase, Aurora A plays diverse functions during anaphase, essentially participating in astral microtubules dynamics and central spindle assembly and functioning. The present review describes the experimental systems used to decipher new functions of Aurora A during late mitosis and situate these functions into the context of cytokinesis mechanisms.
Forces positioning the mitotic spindle: Theories, and now experiments.
Wu, Hai-Yin; Nazockdast, Ehssan; Shelley, Michael J; Needleman, Daniel J
The position of the spindle determines the position of the cleavage plane, and is thus crucial for cell division. Although spindle positioning has been extensively studied, the underlying forces ultimately responsible for moving the spindle remain poorly understood. A recent pioneering study by Garzon-Coral et al. uses magnetic tweezers to perform the first direct measurements of the forces involved in positioning the mitotic spindle. Combining this with molecular perturbations and geometrical effects, they use their data to argue that the forces that keep the spindle in its proper position for cell division arise from astral microtubules growing and pushing against the cell's cortex. Here, we review these ground-breaking experiments, the various biomechanical models for spindle positioning that they seek to differentiate, and discuss new questions raised by these measurements.
Spatial Frequency Training Modulates Neural Face Processing: Learning Transfers from Low- to High-Level Visual Features
Peters, Judith C.; van den Boomen, Carlijn; Kemner, Chantal
Perception of visual stimuli improves with training, but improvements are specific for trained stimuli rendering the development of generic training programs challenging. It remains unknown to which extent training of low-level visual features transfers to high-level visual perception, and whether this is accompanied by neuroplastic changes. The current event-related potential (ERP) study showed that training-induced increased sensitivity to a low-level feature, namely low spatial frequency (LSF), alters neural processing of this feature in high-level visual stimuli. Specifically, neural activity related to face processing (N170), was decreased for low (trained) but not high (untrained) SF content in faces following LSF training. These novel results suggest that: (1) SF discrimination learning transfers from simple stimuli to complex objects; and that (2) training the use of specific SF information affects neural processing of facial information. These findings may open up a new avenue to improve face recognition skills in individuals with atypical SF processing, such as in cataract or Autism Spectrum Disorder (ASD). PMID:28149275
High-order feature-based mixture models of classification learning predict individual learning curves and enable personalized teaching.
Cohen, Yarden; Schneidman, Elad
Pattern classification learning tasks are commonly used to explore learning strategies in human subjects. The universal and individual traits of learning such tasks reflect our cognitive abilities and have been of interest both psychophysically and clinically. From a computational perspective, these tasks are hard, because the number of patterns and rules one could consider even in simple cases is exponentially large. Thus, when we learn to classify we must use simplifying assumptions and generalize. Studies of human behavior in probabilistic learning tasks have focused on rules in which pattern cues are independent, and also described individual behavior in terms of simple, single-cue, feature-based models. Here, we conducted psychophysical experiments in which people learned to classify binary sequences according to deterministic rules of different complexity, including high-order, multicue-dependent rules. We show that human performance on such tasks is very diverse, but that a class of reinforcement learning-like models that use a mixture of features captures individual learning behavior surprisingly well. These models reflect the important role of subjects' priors, and their reliance on high-order features even when learning a low-order rule. Further, we show that these models predict future individual answers to a high degree of accuracy. We then use these models to build personally optimized teaching sessions and boost learning.
High-order feature-based mixture models of classification learning predict individual learning curves and enable personalized teaching
Cohen, Yarden; Schneidman, Elad
Pattern classification learning tasks are commonly used to explore learning strategies in human subjects. The universal and individual traits of learning such tasks reflect our cognitive abilities and have been of interest both psychophysically and clinically. From a computational perspective, these tasks are hard, because the number of patterns and rules one could consider even in simple cases is exponentially large. Thus, when we learn to classify we must use simplifying assumptions and generalize. Studies of human behavior in probabilistic learning tasks have focused on rules in which pattern cues are independent, and also described individual behavior in terms of simple, single-cue, feature-based models. Here, we conducted psychophysical experiments in which people learned to classify binary sequences according to deterministic rules of different complexity, including high-order, multicue-dependent rules. We show that human performance on such tasks is very diverse, but that a class of reinforcement learning-like models that use a mixture of features captures individual learning behavior surprisingly well. These models reflect the important role of subjects' priors, and their reliance on high-order features even when learning a low-order rule. Further, we show that these models predict future individual answers to a high degree of accuracy. We then use these models to build personally optimized teaching sessions and boost learning. PMID:23269833
Applicability of data mining algorithms in the identification of beach features/patterns on high-resolution satellite data
NASA Astrophysics Data System (ADS)
Teodoro, Ana C.
The available beach classification algorithms and sediment budget models are mainly based on in situ parameters, usually unavailable for several coastal areas. A morphological analysis using remotely sensed data is a valid alternative. This study focuses on the application of data mining techniques, particularly decision trees (DTs) and artificial neural networks (ANNs) to an IKONOS-2 image in order to identify beach features/patterns in a stretch of the northwest coast of Portugal. Based on knowledge of the coastal features, five classes were defined. In the identification of beach features/patterns, the ANN algorithm presented an overall accuracy of 98.6% and a kappa coefficient of 0.97. The best DTs algorithm (with pruning) presents an overall accuracy of 98.2% and a kappa coefficient of 0.97. The results obtained through the ANN and DTs were in agreement. However, the ANN presented a classification more sensitive to rip currents. The use of ANNs and DTs for beach classification from remotely sensed data resulted in an increased classification accuracy when compared with traditional classification methods. The association of remotely sensed high-spatial resolution data and data mining algorithms is an effective methodology with which to identify beach features/patterns.
Li Xiaobo; Zhang Hongqi
We investigate the origin, configuration, and evolution of moving magnetic features (MMFs) in the moat and penumbra regions of NOAA AR 10930 using Hinode/SOT filtergrams and magnetograms. We differentiate MMFs into four types in terms of the location of first appearance and the source of initial flux. The main results are summed up as follows: (1) 50% of the MMFs are produced from or within the penumbra, while 50% are produced within the moat. The MMFs formed in the penumbra normally move outward along radial directions. The MMFs formed in the moat have more dispersed directions of motion. The average speed of most MMFs decreases radially. (2) About 63% of moat fluxes are input by flux emergences. Newly emerged MMFs are normally smaller in size. In their rise phase, they gain flux by adding newly emerging flux or merging other elements, and in the decline phase they lose flux by flux cancellation or fragmentation. The MMFs that are fragments separated from penumbra or other magnetic elements usually have larger flux and longer lifetime. They start their decay process once they are formed. Frequent merging and flux cancellation between MMFs are the dominant factors in MMFs' evolution. (3) Cancellations between opposite-polarity magnetic elements are responsible for most of the low chromospheric bright points. Bipole emergence and MMFs' severance from the penumbra also produce bright points. Elongated or horn-shaped micro-filaments may appear during the separation or cancellation process between magnetic elements.
The features of steel surface hardening with high energy heating by high frequency currents and shower cooling
NASA Astrophysics Data System (ADS)
Ivancivsky, V. V.; Skeeba, V. Yu; Bataev, I. A.; Lobanov, D. V.; Martyushev, N. V.; Sakha, O. V.; Khlebova, I. V.
The paper examines the process of surface hardening of steel 45 with the help of high energy heating by high frequency currents with simultaneous shower water cooling. We theoretically justified and experimentally proved a possibility of liquid phase forming in the course of heating not on the surface, but in the depth of the surface layer.
A feature study of innovative high-speed lancing device and safety lancet.
Chang, Ho; Yeh, Yao-Jen; Lee, Rahnfong; Shyu, Jenq-Huey
The study developed two models of an innovative high-speed lancing device and safety lancet, where the specially designed structure causes high-speed motion of the lancet, resulting in only one puncture of the skin. The two experimental models and other lancing devices sold on market were compared in order to: (1) measure the forces of lancets piercing animal skin by a load cell; (2) observe the wound areas caused by lancing devices under a microscope. The experimental results showed that, after using this innovative high-speed lancing device, the maximum force of a lancet piercing skin is only 1/3 of the force of conventional lancing devices, and the duration of the former under the skin is 1/6 of the latter. In addition, the wound area caused by the innovative lancing device is 20 % smaller than those of the conventional lancing devices. Usage of this innovative high-speed safety lancet shows that its maximum skin-piercing force is only 2/3 of conventional safety lancets, its duration under the skin is 1/4 of conventional safety lancets, and the wound area is 12 % smaller. In conclusion, both the innovative high-speed lancing device and safety lancet are proved effective in alleviating pain for diabetics and shortening the recovering time for wounds, thus, providing a more comfortable process for the self-monitoring of blood glucose.
Early developmental stages of Ascaris lumbricoides featured by high-resolution mass spectrometry.
Melo, Carlos Fernando Odir Rodrigues; Esteves, Cibele Zanardi; de Oliveira, Rosimeire Nunes; Guerreiro, Tatiane Melina; de Oliveira, Diogo Noin; Lima, Estela de Oliveira; Miné, Júlio César; Allegretti, Silmara Marques; Catharino, Rodrigo Ramos
Ascaris lumbricoides is responsible for a highly disseminated helminth parasitic disease, ascariosis, a relevant parasitosis that responds for great financial burden on the public health system of developing countries. In this work, metabolic fingerprinting using high-resolution mass spectrometry (HRMS) was employed to identify marker molecules from A. lumbricoides in different development stages. We have identified nine biomarkers, such as pheromones and steroidal prohormones in early stages, among other molecules in late development stages, making up four molecules for fertilized eggs, four marker molecules for first larvae (L1) and one marker molecule for third larvae (L3). Therefore, our findings indicate that this approach is suitable for biochemical characterization of A. lumbricoides development stages. Moreover, the straightforward analytical method employed, with almost no sample preparation from a complex matrix (feces) using high-resolution mass spectrometry, suggests that it is possible to seek for an easier and faster way to study animal molding processes.
The Luminous Polycyclic Aromatic Hydrocarbon Emission Features: Applications to High Redshift Galaxies and Active Galactic Nuclei
NASA Astrophysics Data System (ADS)
Shipley, Heath; Papovich, Casey
We provide a new robust star-formation rate (SFR) calibration using the luminosity from polycyclic aromatic hydrogen (PAH) molecules. The PAH features emit strongly in the mid-infrared (mid-IR; 3-19μm), mitigating dust extinction, and they are very luminous, containing 5-10% of the total IR luminosity in galaxies. We derive the calibration of the PAH luminosity as a SFR indicator using a sample of 105 star-forming galaxies covering a range of total IR luminosity, LIR = L(8-1000μm) = 109 - 1012 L⊙ and redshift 0 < z < 0.6. The PAH luminosity correlates linearly with the SFR as measured by the dust-corrected Hα luminosity (using the sum of the Hα and rest-frame 24μm luminosity from Kennicutt et al. 2009), with tight scatter of ~0.15 dex, comparable to the scatter in the dust-corrected Hα SFRs and Paα SFRs. We show this relation is sensitive to galaxy metallicity, where the PAH luminosity of galaxies with Z < 0.7 Z⊙ departs from the linear SFR relationship but in a behaved manor. We derive for this a correction to galaxies below solar metallicity. As a case study for observations with JWST, we apply the PAH SFR calibration to a sample of lensed galaxies at 1 < z < 3 with Spitzer Infrared Spectrograph (IRS) data, and we demonstrate the utility of PAHs to derive SFRs as accurate as those available from any other indicator. This new SFR indicator will be useful for probing the peak of the SFR density of the universe (1 < z < 3) and for studying the coevolution of star-formation and supermassive blackhole accretion contemporaneously in a galaxy.
The Saccharomyces cerevisiae spindle pole body duplication gene MPS1 is part of a mitotic checkpoint
M-phase checkpoints inhibit cell division when mitotic spindle function is perturbed. Here we show that the Saccharomyces cerevisiae MPS1 gene product, an essential protein kinase required for spindle pole body (SPB) duplication (Winey et al., 1991; Lauze et al., 1995), is also required for M-phase check-point function. In cdc31-2 and mps2-1 mutants, conditional failure of SPB duplication results in cell cycle arrest with high p34CDC28 kinase activity that depends on the presence of the wild-type MAD1 checkpoint gene, consistent with checkpoint arrest of mitosis. In contrast, mps1 mutant cells fail to duplicate their SPBs and do not arrest division at 37 degrees C, exhibiting a normal cycle of p34CDC28 kinase activity despite the presence of a monopolar spindle. Double mutant cdc31-2, mps1-1 cells also fail to arrest mitosis at 37 degrees C, despite having SPB structures similar to cdc31-2 single mutants as determined by EM analysis. Arrest of mitosis upon microtubule depolymerization by nocodazole is also conditionally absent in mps1 strains. This is observed in mps1 cells synchronized in S phase with hydroxyurea before exposure to nocodazole, indicating that failure of checkpoint function in mps1 cells is independent of SPB duplication failure. In contrast, hydroxyurea arrest and a number of other cdc mutant arrest phenotypes are unaffected by mps1 alleles. We propose that the essential MPS1 protein kinase functions both in SPB duplication and in a mitotic checkpoint monitoring spindle integrity. PMID:8567717
Theories and Practices of Environmental Education in Quebec High Schools: Main Features of a Critical Diagnosis.
ERIC Educational Resources Information Center
Sauve, Lucie; Boutard, Armel; Begin, Rachel; Orellana, Isabel
This paper reports on research about professional development programs in environmental education for high school teachers in Quebec (Canada). A diagnostic research study was conducted to attempt to answer two questions: (1) what is the current status of environmental education in this sector of formal education?; and (2) how is environmental…
Relationships among Repetitive Behaviors, Sensory Features, and Executive Functions in High Functioning Autism
ERIC Educational Resources Information Center
Boyd, Brian A.; McBee, Matthew; Holtzclaw, Tia; Baranek, Grace T.; Bodfish, James W.
This study examined the relationship between repetitive behaviors and sensory processing issues in school-aged children with high functioning autism (HFA). Children with HFA (N = 61) were compared to healthy, typical controls (N = 64) to determine the relationship between these behavioral classes and to examine whether executive dysfunction…
Binding of Multiple Features in Memory by High-Functioning Adults with Autism Spectrum Disorder
ERIC Educational Resources Information Center
Bowler, Dermot M.; Gaigg, Sebastian B.; Gardiner, John M.
Diminished episodic memory and diminished use of semantic information to aid recall by individuals with autism spectrum disorder (ASD) are both thought to result from diminished relational binding of elements of complex stimuli. To test this hypothesis, we asked high-functioning adults with ASD and typical comparison participants to study grids in…
Multi-Beam, High-Power Rayleigh Lidar for the Capture of 2D Dynamic Atmospheric Features
NASA Astrophysics Data System (ADS)
Hall, S.; Swenson, G. R.
While single-beam Rayleigh lidar have been in common usage for decades, their lack of horizontal resolution limits their ability to study the dynamic structure of the atmosphere to what can be observed in a single vertical profile. An experimental multi-beam lidar transmitter at the University of Illinois overcomes this problem by the simultaneous generation of a fan of closely-spaced near-vertical beams from a single high-power pulsed laser, allowing for the resolution of horizontal features on the order of tens of meters and the capture of dynamic events such as billows and overturnings. This transmitter is coupled with a digital receiver that allows for quickly variable vertical resolution that can be dynamically varied to match the scale of observed features.
Closed MAD2 (C-MAD2) is selectively incorporated into the mitotic checkpoint complex (MCC)
Tipton, Aaron R; Tipton, Michael; Yen, Tim
The mitotic checkpoint is a specialized signal transduction pathway that monitors kinetochore-microtubule attachment to achieve faithful chromosome segregation. MAD2 is an evolutionarily conserved mitotic checkpoint protein that exists in open (O) and closed (C) conformations. The increase of intracellular C-MAD2 level during mitosis, through O→C-MAD2 conversion as catalyzed by unattached kinetochores, is a critical signaling event for the mitotic checkpoint. However, it remains controversial whether MAD2 is an integral component of the effector of the mitotic checkpoint—the mitotic checkpoint complex (MCC). We show here that endogenous human MCC is assembled by first forming a BUBR1:BUB3:CDC20 complex in G2 and then selectively incorporating C-MAD2 during mitosis. Nevertheless, MCC can be induced to form in G1/S cells by expressing a C-conformation locked MAD2 mutant, indicating intracellular level of C-MAD2 as a major limiting factor for MCC assembly. In addition, a recombinant MCC containing C-MAD2 exhibits effective inhibitory activity toward APC/C isolated from mitotic HeLa cells, while a recombinant BUBR1:BUB3:CDC20 ternary complex is ineffective at comparable concentrations despite association with APC/C. These results help establish a direct connection between a major signal transducer (C-MAD2) and the potent effector (MCC) of the mitotic checkpoint, and provide novel insights into protein-protein interactions during assembly of a functional MCC. PMID:22037211
Induction of mitotic catastrophe by PKC inhibition in Nf1-deficient cells.
Zhou, Xiaodong; Kim, Sung-Hoon; Shen, Ling; Lee, Hyo-Jung; Chen, Changyan
Mutations of tumor suppressor Nf1 gene deregulate Ras-mediated signaling, which confers the predisposition for developing benign or malignant tumors. Inhibition of protein kinase C (PKC) was shown to be in synergy with aberrant Ras for the induction of apoptosis in various types of cancer cells. However, it has not been investigated whether loss of PKC is lethal for Nf1-deficient cells. In this study, using HMG (3-hydroxy-3-methylgutaryl, a PKC inhibitor), we demonstrate that the inhibition of PKC by HMG treatment triggered a persistently mitotic arrest, resulting in the occurrence of mitotic catastrophe in Nf1-deficient ST8814 cells. However, the introduction of the Nf1 effective domain gene into ST8814 cells abolished this mitotic crisis. In addition, HMG injection significantly attenuated the growth of the xenografted ST8814 tumors. Moreover, Chk1 was phosphorylated, accompanied with the persistent increase of cyclin B1 expression in HMG-treated ST8814 cells. The knockdown of Chk1 by the siRNA prevented the Nf1-deficient cells from undergoing HMG-mediated mitotic arrest as well as mitotic catastrophe. Thus, our data suggested that the suppression of PKC activates the Chk1-mediated mitotic exit checkpoint in Nf1-deficient cells, leading to the induction of apoptosis via mitotic catastrophe. Collectively, the study indicates that targeting PKC may be a potential option for developing new strategies to treat Nf1-deficiency-related diseases.
Morphological features of the copper surface layer under sliding with high density electric current
Fadin, V. V.; Aleutdinova, M. I.; Rubtsov, V. Ye.; Aleutdinova, V. A.
Conductivity and wear intensity of copper under the influence of dry friction and electric current with contact density higher 100 A/cm{sup 2} are presented. It is shown that an increase in hardness and heat outflow from a friction zone leads to the reduction of wear intensity and current contact density increase corresponding to the beginning of catastrophic wear. Structural changes, such as the formation of FeO oxide and α-Fe particles in the copper surface layer, have also been found. It is observed that a worn surface is deformed according to a viscous liquid mechanism. Such singularity is explained in terms of appearance of high-excited atomic states in deforming micro-volumes near contact spots that lead to easy stress relaxation by local plastic shears in the vicinity of stress concentrators. In common this effect allows to achieve high wear resistance.
New high-performance complementary bipolar technology featuring 45-GHz NPN and 20-GHz PNP devices
NASA Astrophysics Data System (ADS)
Wilson, Martin C.; Osborne, Peter H.; Thomas, Simon; Cook, Trevor
A new high performance silicon complementary bipolar technology is introduced. In addition a novel process 'enhancement' technique based on a local oxidation is described and demonstrated and NPN devices with cut-off frequencies up to 45GHz and PNP devices of 20GHz have been fabricate. We propose that the technique we have used will allow specific transistors within a circuit to be optimized, as required.
Curcumin affects components of the chromosomal passenger complex and induces mitotic catastrophe in apoptosis-resistant Bcr-Abl-expressing cells.
Wolanin, Kamila; Magalska, Adriana; Mosieniak, Grazyna; Klinger, Rut; McKenna, Sharon; Vejda, Susanne; Sikora, Ewa; Piwocka, Katarzyna
The Bcr-Abl oncoprotein plays a major role in the development and progression of chronic myeloid leukemia and is a determinant of chemotherapy resistance occurring during the blast crisis phase of the disease. The aim of this article was to investigate the possibility of combating the resistance to apoptosis caused by Bcr-Abl by inducing an alternative cell death process. As a model of chronic myeloid leukemia, we employed Bcr-Abl-transfected mouse progenitor 32D cells with low and high Bcr-Abl expression levels corresponding to drug-sensitive and drug-resistant cells, respectively. The drug curcumin (diferuloylmethane), a known potent inducer of cell death in many cancer cells, was investigated for efficacy with Bcr-Abl-expressing cells. Curcumin strongly inhibited cell proliferation and affected cell viability by inducing apoptotic symptoms in all tested cells; however, apoptosis was a relatively late event. G(2)-M cell cycle arrest, together with increased mitotic index and cellular and nuclear morphology resembling those described for mitotic catastrophe, was observed and preceded caspase-3 activation and DNA fragmentation. Mitosis-arrested cells displayed abnormal chromatin organization, multipolar chromosome segregation, aberrant cytokinesis, and multinucleated cells-morphologic changes typical of mitotic catastrophe. We found that the mitotic cell death symptoms correlated with attenuated expression of survivin, a member of the chromosomal passenger complex, and mislocalization of Aurora B, the partner of survivin in the chromosomal passenger complex. Inhibition of survivin expression with small interfering RNA exhibited similar mitotic disturbances, thus implicating survivin as a major, albeit not the only, target for curcumin action. This study shows that curcumin can overcome the broad resistance to cell death caused by expression of Bcr-Abl and suggests that curcumin may be a promising agent for new combination regimens for drug-resistant chronic myeloid
Two different mitotic checkpoint inhibitors of the anaphase-promoting complex/cyclosome antagonize the action of the activator Cdc20
Eytan, Esther; Braunstein, Ilana; Ganoth, Dvora; Teichner, Adar; Hittle, James C.; Yen, Tim J.; Hershko, Avram
The mitotic checkpoint system ensures the fidelity of chromosome segregation by preventing the completion of mitosis in the presence of any misaligned chromosome. When activated, it blocks the initiation of anaphase by inhibiting the ubiquitin ligase anaphase-promoting complex/cyclosome (APC/C). Little is known about the biochemical mechanisms by which this system inhibits APC/C, except for the existence of a mitotic checkpoint complex (MCC) inhibitor of APC/C composed of the APC/C activator Cdc20 associated with the checkpoint proteins Mad2, BubR1, and Bub3. We have been studying the mechanisms of the mitotic checkpoint system in extracts that reproduce its downstream events. We found that inhibitory factors are associated with APC/C in the checkpoint-arrested state, which can be recovered from immunoprecipitates. Only a part of the inhibitory activity was caused by MCC [Braunstein I, Miniowitz S, Moshe Y, Hershko A (2007) Proc Natl Acad Sci USA 104:4870–4875]. Here, we show that during exit from checkpoint, rapid disassembly of MCC takes place while APC/C is still inactive. This observation suggested the possible involvement of multiple factors in the regulation of APC/C by the mitotic checkpoint. We have separated a previously unknown inhibitor of APC/C from MCC. This inhibitor, called mitotic checkpoint factor 2 (MCF2), is associated with APC/C only in the checkpoint-arrested state. The inhibition of APC/C by both MCF2 and MCC was decreased at high concentrations of Cdc20. We propose that both MCF2 and MCC inhibit APC/C by antagonizing Cdc20, possibly by interaction with the Cdc20-binding site of APC/C. PMID:18591651
A prognosis based classification of undifferentiated uterine sarcomas: identification of mitotic index, hormone receptors and YWHAE-FAM22 translocation status as predictors of survival.
Gremel, Gabriela; Liew, Markus; Hamzei, Farzaneh; Hardell, Elin; Selling, Jonas; Ghaderi, Mehran; Stemme, Sten; Pontén, Fredrik; Carlson, Joseph W
Undifferentiated uterine sarcomas (UUS) are rare tumors with a heterologous biology and a poor prognosis. The goal of this study was to examine clinicopathology, biomarkers and YWHAE-FAM22 translocation status, in the prognosis of these tumors. Twenty-six cases of UUS were included. All original slides were rereviewed and age at diagnosis, tumor stage, "Kurihara" diagnosis, mitotic index, presence of necrosis and grade of nuclear atypia were recorded. Additionally, a tissue microarray was constructed from 22 of the cases, and the protein biomarkers P53, P16, Ki-67, Cyclin-D1, ER, PR and ANLN were evaluated by immunohistochemistry. All tumors were evaluated for the presence of a YWHAE-FAM translocation; the translocation was demonstrated in the three Cyclin-D1 positive tumors. Follow-up data in the form of overall survival were available on all patients. These tumors could be divided into two prognostic groups, a high mitotic index group (10 cases, M = 36.8, SD = 5.4) and a low mitotic index group (16 cases, M = 8.7, SD = 5.8). These two groups showed a statistically significant difference in prognosis. The expression of ER, PR or presence of the YWHAE-FAM22 translocation correlated with low mitotic index and an additionally improved prognosis, although the number of cases was small. These results indicate that UUS can be divided into two prognostic groups using mitotic index as a primary criteria, followed by expression of either ER, PR or the presence of a YWHAE-FAM22 translocation as a secondary criteria. This study demonstrates the presence of statistically significant prognostic subgroups within UUS, and provides treatment insights.
Very compact, high-stability electrostatic actuator featuring contact-free self-limiting displacement
Rodgers, M. Steven; Miller, Samuel L.
A compact electrostatic actuator is disclosed for microelectromechanical (MEM) applications. The actuator utilizes stationary and moveable electrodes, with the stationary electrodes being formed on a substrate and the moveable electrodes being supported above the substrate on a frame. The frame provides a rigid structure which allows the electrostatic actuator to be operated at high voltages (up to 190 Volts) to provide a relatively large actuation force compared to conventional electrostatic comb actuators which are much larger in size. For operation at its maximum displacement, the electrostatic actuator is relatively insensitive to the exact value of the applied voltage and provides a self-limiting displacement.
Proposed criteria for recognizing intrastratal deformation features in marine high resolution seismic reflection profiles
O'Leary, D. W.; Laine, E.
Intrastratal deformation of marine strata is ordinarily recorded in high-resolution seismic reflection profiles as acoustically transparent or "chaotic" intervals marked by hyperbolic echoes. Intrastratal deformation is easily confused with buried slump or slide deposits formed initially at the sea floor. Correct identification of intrastratal deformation depends on the presence of a warped continuously reflective layer overlying a chaotic/transparent layer. Decollement is the key criterion for identification in seismic reflection profiles. Other criteria include intrusive structures or faults rooted in a chaotic/transparent layer and thickening and thinning of a chaotic/transparent layer with transitions to reflective intervals.
A chemical tool box defines mitotic and interphase roles for Mps1 kinase
Lan, Weijie
In this issue, three groups (Hewitt et al. 2010. J. Cell Biol. doi:10.1083/jcb.201002133; Maciejowski et al. 2010. J. Cell Biol. doi:10.1083/jcb.201001050; Santaguida et al. 2010. J. Cell Biol. doi:10.1083/jcb.201001036) use chemical inhibitors to analyze the function of the mitotic checkpoint kinase Mps1. These studies demonstrate that Mps1 kinase activity ensures accurate chromosome segregation through its recruitment to kinetochores of mitotic checkpoint proteins, formation of interphase and mitotic inhibitors of Cdc20, and correction of faulty microtubule attachments. PMID:20624898
Mitotic spindle assembly on chromatin patterns made with deep UV photochemistry.
Tarnawska, Katarzyna; Pugieux, Céline; Nédélec, François
We provide a detailed method to generate arrays of mitotic spindles in vitro. Spindles are formed in extract prepared from unfertilized Xenopus laevis eggs, which contain all the molecular ingredients of mitotic spindles. The method is based on using deep UV photochemistry to attach chromatin-coated beads on a glass surface according to a pattern of interest. The immobilized beads act as artificial chromosomes, and induce the formation of mitotic spindles in their immediate vicinity. To perform the experiment, a chamber is assembled over the chromatin pattern, Xenopus egg extract is flowed in and after incubation the spindles are imaged with a confocal microscope.
[Mitotic activity of the lymphocytes of the thymus cortex in hypokinesia during the period of readaptation].
Kharlova, G V; Li, S E
The changes in the weight and mitotic index were studied in the cortex of the thymus of Wistar rats during 10-day hypokinesia and 10-day readaptation (restoration). 24 hours after immobilization of the animals the mitotic index was 2 times as lower. No complete readaptation was attained during 10-day hypokinesia. No readaptation was attained during 10-day hypokinesia. In readaptation the stage of secondary stress was found (the mitotic index was 3.5 times as reduced), the stage of genuine restoration being revealed after 10 days.
Understanding the structural features of high-amylose maize starch through hydrothermal treatment.
Yang, Jianing; Xie, Fengwei; Wen, Wenqiang; Chen, Ling; Shang, Xiaoqin; Liu, Peng
In this study, high-amylose starches were hydrothermally-treated and the structural changes were monitored with time (up to 12h) using scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), small-angle X-ray scattering (SAXS), X-ray diffraction (XRD), and differential scanning calorimetry (DSC). When high-amylose starches were treated in boiling water, half-shell-like granules were observed by SEM, which could be due to the first hydrolysis of the granule inner region (CLSM). This initial hydrolysis could also immediately (0.5h) disrupt the semi-crystalline lamellar regularity (SAXS) and dramatically reduce the crystallinity (XRD); but with prolonged time of hydrothermal treatment (≥2 h), might allow the perfection or formation of amylose single helices, resulting in slightly increased crystallinity (XRD and DSC). These results show that the inner region of granules is composed of mainly loosely-packed amylopectin growth rings with semi-crystalline lamellae, which are vulnerable under gelatinization or hydrolysis. In contrast, the periphery is demonstrated to be more compact, possibly composed of amylose and amylopectin helices intertwined with amylose molecules, which require greater energy input (higher temperature) for disintegration.
High-speed AFM for 1x node metrology and inspection: Does it damage the features?
NASA Astrophysics Data System (ADS)
Sadeghian, Hamed; van den Dool, Teun C.; Uziel, Yoram; Bar Or, Ron
This paper aims at unraveling the mystery of damage in high speed AFMs for 1X node and below. With the device dimensions moving towards the 1X node and below, the semiconductor industry is rapidly approaching the point where existing metrology, inspection and review tools face huge challenges in terms of resolution, the ability to resolve 3D, and throughput. In this paper, we critically asses the important issue of damage in high speed AFM for metrology and inspection of semiconductor wafers. The issues of damage in four major scanning modes (contact mode, tapping mode, non-contact mode, and peak force tapping mode) are described to show which modes are suitable for which applications and which conditions are damaging. The effects of all important scanning parameters on resulting damage are taken into account for materials such as silicon, photoresists and low K materials. Finally, we recommend appropriate scanning parameters and conditions for several use cases (FinFET, patterned photoresist, HAR structures) that avoid exceeding a critical contact stress such that sample damage is minimized. In conclusion, we show using our theoretical analysis that selecting parameters that exceed the target contact stress, indeed leads to significant damage. This method provides AFM users for metrology with a better understanding of contact stresses and enables selection of AFM cantilevers and experimental parameters that prevent sample damage.
Alterations in the mitotic index of Allium cepa induced by infusions of Pluchea sagittalis submitted to three different cultivation systems.
Rossato, Liana V; Tedesco, Solange B; Laughinghouse, Haywood D; Farias, Júlia G; Nicoloso, Fernando T
We evaluated the antiproliferative effect of infusions from Pluchea sagittalis using the Allium cepa test. Infusions in three concentrations (2.5, 5, and 25 g dm-3) of leaves cultivated in three environments (in vitro, acclimatized growth chamber, and field) were used. Six onion bulbs were used for each of the eight treatments, and the mitotic index was obtained from 6000 cells per treatment. In conclusion, leaf infusions of P. sagittalis cultivated in the field have a high antiproliferative activity, as well as the cultivation system influences the antiproliferative potential.
Collecting Inexpensive High Resolution Aerial and Stereo Images of Small- to Mid-Scale Geomorphic and Tectonic Features
NASA Astrophysics Data System (ADS)
Wheelwright, R. J.; White, W. S.; Willis, J. B.
Methods for collecting accurate, mm- to cm-scale stereoscopic aerial imagery of both small- and mid-scale geomorphic features are developed for a one-time cost of under $1500. High resolution aerial images are valuable for documenting and analyzing small- to mid-scale geomorphic and tectonic features. However, collecting images of mid-scale features such as landslides, rock glaciers, fault scarps, and cinder cones is expensive and makes studies that rely on high resolution repeat imagery prohibitive for undergraduate geology departments with limited budgets. In addition to cost, collecting images of smaller scale geomorphic features such as gravel bars is often impeded by overhanging vegetation or other features in the immediate environment that make impractical the collection of aerial images using standard airborne techniques. The methods provide high resolution stereo photos suitable for image processing and stereographic analysis; the images are potentially suitable for change analyses, velocity tracking, and construction of lidar-resolution digital elevation models. We developed two techniques. The technique suitable for small-scale features (such as gravel bars) utilizes two Nikon D3000 digital single-lens reflex (DSLR) cameras attached to a system of poles that suspends the cameras at a height of 4 meters with a variable camera separation of 0.6 to 0.9 m. The poles are oriented such that they do not appear in the photographs. The cameras are simultaneously remotely activated to collect stereo pairs at a resolution of 64 pixels/cm2 (pixel length is 1.2 mm). Ground control on the images is provided by pegs placed 5 meters apart, GPS positioning, and a meter-stick included in each photograph. Initial photo data gathered of a gravel bar on the Henry's Fork of the Snake River, north of Rexburg, Idaho is sharp and readily segmented using the MatLab-based CLASTS image processing algorithm. The technique developed for imaging mid-scale features (such as cinder
Modeling of geomagnetic activity due to passage of different structures and features of high speed streams
NASA Astrophysics Data System (ADS)
Mustajab, Fainana
The modeling of terrestrial environment and relative geoeffectiveness due to high speed streams of different type and also compare their geoeffectiveness due to fine structures associated with streams, for example i) streams with different speed, ii) streams with different durations, iii) streams from different solar source and iv) associated fine structures. We also observed high speed streams during 1996 to 2011, and divided them into convenient groups based on their i) speed, ii) durations, iii) solar sources and iv) Dst groups. Performed them method of superposed-epoch analysis and other some statistical-analysis and correlation analysis between geomagnetic index Dst and plasma/field parameters during for both main phase and recovery phase. Streams having the passage duration ranging from 4.5 days to 10.5 days is 59% while other groups, having passage duration <4.5 days and > 10.5 days, contribute only near about 13%. When we observe group according to speed of streams, 30% of high speed streams are having the speed >650km/s and other groups are near about equally distributed in the range 400km/s to 650km/s. Out of 575 high speed streams, 45% streams are caused by single coronal hole, 20% due to multiple coronal hole, 24% by compound i.e: due to coronal hole and coronal mass ejections and only 10% from coronal mass ejections. The streams which are responsible for quiet, weak, moderate storms are nearly equal and only 12% streams cause severe storms. Dst gives best correlation with V(km/s) and BVres to the power 2 (x10res to the power 6) for over all storm time. B(nT) and BV(x10res to the power 3) represent good correlation with Dst during recovery phase duration for the speed groups. I observed the percentage of quiet storms decreases with increasing speed of streams. Near about equal percentage of weak storm are observed in each set of speed of stream. 17% moderate storms are found to contribute for the speed range 400-550km/s and ≈33% contribution is
DE/ISIS conjunction comparisons of high-latitude electron density features
NASA Technical Reports Server (NTRS)
Hoegy, Walter R.; Benson, Robert F.
This paper presents a comparison between the ISIS-1 and -2 topside sounder measurements of electron number density, N(e), with the in situ ion and N(e) measurements by the Langmuir probe aboard the Dynamics Explorer 2 (DE 2) during four high-latitude ISIS/DE magnetic field-aligned conjunctions. The ISIS-derived N(e) values, even at the greatest distance from the sounder, were found to agree with the Langmuir probe measurements to within about 30 percent over a density range of more than two decades on three of the four comparisons; the fourth comparison which included data with strong N(e) irregularities, showed a difference of 60 percent.
The importance of study design for detecting differentially abundant features in high-throughput experiments.
Luo, Huaien; Li, Juntao; Chia, Burton Kuan Hui; Robson, Paul; Nagarajan, Niranjan
High-throughput assays, such as RNA-seq, to detect differential abundance are widely used. Variable performance across statistical tests, normalizations, and conditions leads to resource wastage and reduced sensitivity. EDDA represents a first, general design tool for RNA-seq, Nanostring, and metagenomic analysis, that rationally selects tests, predicts performance, and plans experiments to minimize resource wastage. Case studies highlight EDDA's ability to model single-cell RNA-seq, suggesting ways to reduce sequencing costs up to five-fold and improving metagenomic biomarker detection through improved test selection. EDDA's novel mode-based normalization for detecting differential abundance improves robustness by 10% to 20% and precision by up to 140%.
Spectral features and voltage effects in high-field electroluminescence of AlN filamentary nanocrystals
NASA Astrophysics Data System (ADS)
Weinstein, I. A.; Vokhmintsev, A. S.; Chaikin, D. V.; Afonin, Yu. D.
The high-field electroluminescence (EL) spectra for Al-rich AlN nanowhiskers varying applied voltage were studied. The observed 2.70 eV emission, which can be considered as superposition of two Gaussian bands in 2.75 and 2.53 eV, was analyzed. It was shown that Fowler-Nordheim effect took place in EL mechanism with participation of capturing levels of ON- and VN-centers when AlN nanowhiskers were exposed to an external field of 2.5 ÷ 10 V/μm. Obtained results and made conclusions are in a good agreement with independent electron field emission measurements for different one-dimensional AlN nanostructures.
Pathobiological features of a novel, highly pathogenic avian influenza A(H5N8) virus.
Kim, Young-Il; Pascua, Philippe Noriel Q; Kwon, Hyeok-Il; Lim, Gyo-Jin; Kim, Eun-Ha; Yoon, Sun-Woo; Park, Su-Jin; Kim, Se Mi; Choi, Eun-Ji; Si, Young-Jae; Lee, Ok-Jun; Shim, Woo-Sub; Kim, Si-Wook; Mo, In-Pil; Bae, Yeonji; Lim, Yong Taik; Sung, Moon Hee; Kim, Chul-Joong; Webby, Richard J; Webster, Robert G; Choi, Young Ki
The endemicity of highly pathogenic avian influenza (HPAI) A(H5N1) viruses in Asia has led to the generation of reassortant H5 strains with novel gene constellations. A newly emerged HPAI A(H5N8) virus caused poultry outbreaks in the Republic of Korea in 2014. Because newly emerging high-pathogenicity H5 viruses continue to pose public health risks, it is imperative that their pathobiological properties be examined. Here, we characterized A/mallard duck/Korea/W452/2014 (MDk/W452(H5N8)), a representative virus, and evaluated its pathogenic and pandemic potential in various animal models. We found that MDk/W452(H5N8), which originated from the reassortment of wild bird viruses harbored by migratory waterfowl in eastern China, replicated systemically and was lethal in chickens, but appeared to be attenuated, albeit efficiently transmitted, in ducks. Despite predominant attachment to avian-like virus receptors, MDk/W452(H5N8) also exhibited detectable human virus-like receptor binding and replicated in human respiratory tract tissues. In mice, MDk/W452(H5N8) was moderately pathogenic and had limited tissue tropism relative to previous HPAI A(H5N1) viruses. It also induced moderate nasal wash titers in inoculated ferrets; additionally, it was recovered in extrapulmonary tissues and one of three direct-contact ferrets seroconverted without shedding. Moreover, domesticated cats appeared to be more susceptible than dogs to virus infection. With their potential to become established in ducks, continued circulation of A(H5N8) viruses could alter the genetic evolution of pre-existing avian poultry strains. Overall, detailed virological investigation remains a necessity given the capacity of H5 viruses to evolve to cause human illness with few changes in the viral genome.
Novel digital diffractive tags integrating anti-counterfeiting, tamper-evident, and high-density WORM data storage features
NASA Astrophysics Data System (ADS)
Boisdur, Enrick; Kress, Bernard
Embossed holographic tags for security and anti-counterfeiting applications are being used by industry since many years. However, such elements are not very effective since the detector is usually the human eye, and provides therefore around 80% effective counterfeiting protection of the tag. We present a novel holographic anticounterfeiting technology which provides 99.999% protection against tag counterfeiting. Horus Technologies develops such holographic tags, which include several layers of increasingly secure optical features, from standard visual holographic patterns and OVIDs (Optical Variable Imaging Devices), to micro-holographic text, down to covert features such as encrypted high resolution holographic 1d, 2d and 3d bar codes. We also demonstrate the potential of providing anti-tamper functionality on the same tag, for packaging security (especially for medical packaging). Finally, we demonstrate that more than 1Mb/square mm of digital data can be stored and encrypted on these same tags. A specific low cost laser based reader is developed to read the various security feature of such hybrid universal holographic tags. We also present a way to change and update the encrypted data in the tag in a similar way to RFID tags. Finally, we show a cost effective technique to replicate these structures in volume by roll-to-toll embossing, and even direct by glass molding within the package itself (bottle, vial, etc,..).
Paclitaxel sensitivity of breast cancer cells requires efficient mitotic arrest and disruption of Bcl-xL/Bak interaction.
Flores, M Luz; Castilla, Carolina; Ávila, Rainiero; Ruiz-Borrego, Manuel; Sáez, Carmen; Japón, Miguel A
Taxanes are being used for the treatment of breast cancer. However, cancer cells frequently develop resistance to these drugs with the subsequent recurrence of the tumor. MDA-MB-231 and T-47D breast cancer cell lines were used to assess the effect of paclitaxel treatment on apoptosis and cell cycle, the possible mechanisms of paclitaxel resistance as well as the enhancement of paclitaxel-induced apoptosis based on its combination with phenylethyl isothiocyanate (PEITC). T-47D cells undergo apoptosis in response to paclitaxel treatment. The induction of apoptosis was associated with a robust mitotic arrest and the disruption of Bcl-xL/Bak interaction. By contrary, MDA-MB-231 cells were insensitive to paclitaxel-induced apoptosis and this was associated with a high percentage of cells that slip out of paclitaxel-imposed mitotic arrest and also with the maintenance of Bcl-xL/Bak interaction. The sequential treatment of MDA-MB-231 cells with PEITC followed by paclitaxel inhibited the slippage induced by paclitaxel and increased the apoptosis induction achieved with any of the drugs alone. In breast cancer tissues, high Bcl-xL expression was correlated with a shorter time of disease-free survival in patients treated with a chemotherapeutic regimen that contains paclitaxel, in a statistically significant way. Thus, resistance to paclitaxel in MDA-MB-231 cells is related to the inability to disrupt the Bcl-xL/Bak interaction and increased slippage. In this context, the combination of a drug that induces a strong mitotic arrest, such as paclitaxel, with another that inhibits slippage, such as PEITC, translates into increased apoptotic induction.
High-Resolution Transcriptome Maps Reveal Strain-Specific Regulatory Features of Multiple Campylobacter jejuni Isolates
Förstner, Konrad U.; Heidrich, Nadja; Reinhardt, Richard; Nieselt, Kay; Sharma, Cynthia M.
Campylobacter jejuni is currently the leading cause of bacterial gastroenteritis in humans. Comparison of multiple Campylobacter strains revealed a high genetic and phenotypic diversity. However, little is known about differences in transcriptome organization, gene expression, and small RNA (sRNA) repertoires. Here we present the first comparative primary transcriptome analysis based on the differential RNA–seq (dRNA–seq) of four C. jejuni isolates. Our approach includes a novel, generic method for the automated annotation of transcriptional start sites (TSS), which allowed us to provide genome-wide promoter maps in the analyzed strains. These global TSS maps are refined through the integration of a SuperGenome approach that allows for a comparative TSS annotation by mapping RNA–seq data of multiple strains into a common coordinate system derived from a whole-genome alignment. Considering the steadily increasing amount of RNA–seq studies, our automated TSS annotation will not only facilitate transcriptome annotation for a wider range of pro- and eukaryotes but can also be adapted for the analysis among different growth or stress conditions. Our comparative dRNA–seq analysis revealed conservation of most TSS, but also single-nucleotide-polymorphisms (SNP) in promoter regions, which lead to strain-specific transcriptional output. Furthermore, we identified strain-specific sRNA repertoires that could contribute to differential gene regulation among strains. In addition, we identified a novel minimal CRISPR-system in Campylobacter of the type-II CRISPR subtype, which relies on the host factor RNase III and a trans-encoded sRNA for maturation of crRNAs. This minimal system of Campylobacter, which seems active in only some strains, employs a unique maturation pathway, since the crRNAs are transcribed from individual promoters in the upstream repeats and thereby minimize the requirements for the maturation machinery. Overall, our study provides new insights into
PICH promotes mitotic chromosome segregation: Identification of a novel role in rDNA disjunction.
Nielsen, Christian F; Hickson, Ian D
PICH is an SNF2-family DNA translocase that appears to play a role specifically in mitosis. Characterization of PICH in human cells led to the initial discovery of "ultra-fine DNA bridges" (UFBs) that connect the 2 segregating DNA masses in the anaphase of mitosis. These bridge structures, which arise from specific regions of the genome, are a normal feature of anaphase but had escaped detection previously because they do not stain with commonly used DNA dyes. Nevertheless, UFBs are important for genome maintenance because defects in UFB resolution can lead to cytokinesis failure. We reported recently that PICH stimulates the unlinking (decatenation) of entangled DNA by Topoisomerase IIα (Topo IIα), and is important for the resolution of UFBs. We also demonstrated that PICH and Topo IIα co-localize at the rDNA (rDNA). In this Extra View article, we discuss the mitotic roles of PICH and explore further the role of PICH in the timely segregation of the rDNA locus.
A CEACAM6-High Airway Neutrophil Phenotype and CEACAM6-High Epithelial Cells Are Features of Severe Asthma.
Shikotra, Aarti; Choy, David F; Siddiqui, Salman; Arthur, Greer; Nagarkar, Deepti R; Jia, Guiquan; Wright, Adam K A; Ohri, Chandra M; Doran, Emma; Butler, Claire A; Hargadon, Beverley; Abbas, Alexander R; Jackman, Janet; Wu, Lawren C; Heaney, Liam G; Arron, Joseph R; Bradding, Peter
Severe asthma represents a major unmet clinical need; understanding the pathophysiology is essential for the development of new therapies. Using microarray analysis, we previously found three immunological clusters in asthma: Th2-high, Th17-high, and Th2/17-low. Although new therapies are emerging for Th2-high disease, identifying molecular pathways in Th2-low disease remains an important goal. Further interrogation of our previously described microarray dataset revealed upregulation of gene expression for carcinoembryonic Ag cell adhesion molecule (CEACAM) family members in the bronchi of patients with severe asthma. Our aim was therefore to explore the distribution and cellular localization of CEACAM6 using immunohistochemistry on bronchial biopsy tissue obtained from patients with mild-to-severe asthma and healthy control subjects. Human bronchial epithelial cells were used to investigate cytokine and corticosteroid in vitro regulation of CEACAM6 gene expression. CEACAM6 protein expression in bronchial biopsies was increased in airway epithelial cells and lamina propria inflammatory cells in severe asthma compared with healthy control subjects. CEACAM6 in the lamina propria was localized to neutrophils predominantly. Neutrophil density in the bronchial mucosa was similar across health and the spectrum of asthma severity, but the percentage of neutrophils expressing CEACAM6 was significantly increased in severe asthma, suggesting the presence of an altered neutrophil phenotype. CEACAM6 gene expression in cultured epithelial cells was upregulated by wounding and neutrophil elastase. In summary, CEACAM6 expression is increased in severe asthma and primarily associated with airway epithelial cells and tissue neutrophils. CEACAM6 may contribute to the pathology of treatment-resistant asthma via neutrophil and airway epithelial cell-dependent pathways.
Features of primary damage by high energy displacement cascades in concentrated Ni-based alloys
Béland, Laurent Karim; Lu, Chenyang; Osetskiy, Yuri N.; ...
Alloying of Ni with Fe or Co reduces primary damage production under ion irradiation. Similar results have been obtained from classical molecular dynamics simulations of 1, 10, 20, and 40 keV collision cascades in Ni, NiFe, and NiCo. In all cases, a mix of imperfect stacking fault tetrahedra, faulted loops with a 1/3 {111} Burgers vector, and glissile interstitial loops with a 1/2 {110} Burgers vector were formed, along with small sessile point defect complexes and clusters. Primary damage reduction occurs by three mechanisms. First, Ni-Co, Ni-Fe, Co-Co, and Fe-Fe short-distance repulsive interactions are stiffer than Ni-Ni interactions, which leadmore » to a decrease in damage formation during the transition from the supersonic ballistic regime to the sonic regime. This largely controls final defect production. Second, alloying decreases thermal conductivity, leading to a longer thermal spike lifetime. The associated annealing reduces final damage production. These two mechanisms are especially important at cascades energies less than 40 keV. Third, at the higher energies, the production of large defect clusters by subcascades is inhibited in the alloys. A number of challenges and limitations pertaining to predictive atomistic modeling of alloys under high-energy particle irradiation are discussed.« less
Features of primary damage by high energy displacement cascades in concentrated Ni-based alloys
Béland, Laurent Karim; Lu, Chenyang; Osetskiy, Yuri N.; Samolyuk, German D.; Caro, Alfredo; Wang, Lumin; Stoller, Roger E.
Alloying of Ni with Fe or Co reduces primary damage production under ion irradiation. Similar results have been obtained from classical molecular dynamics simulations of 1, 10, 20, and 40 keV collision cascades in Ni, NiFe, and NiCo. In all cases, a mix of imperfect stacking fault tetrahedra, faulted loops with a 1/3 {111} Burgers vector, and glissile interstitial loops with a 1/2 {110} Burgers vector were formed, along with small sessile point defect complexes and clusters. Primary damage reduction occurs by three mechanisms. First, Ni-Co, Ni-Fe, Co-Co, and Fe-Fe short-distance repulsive interactions are stiffer than Ni-Ni interactions, which lead to a decrease in damage formation during the transition from the supersonic ballistic regime to the sonic regime. This largely controls final defect production. Second, alloying decreases thermal conductivity, leading to a longer thermal spike lifetime. The associated annealing reduces final damage production. These two mechanisms are especially important at cascades energies less than 40 keV. Third, at the higher energies, the production of large defect clusters by subcascades is inhibited in the alloys. A number of challenges and limitations pertaining to predictive atomistic modeling of alloys under high-energy particle irradiation are discussed.
Subsurface Feature Mapping of Mars using a High Resolution Ground Penetrating Radar System
NASA Astrophysics Data System (ADS)
Wu, T. S.; Persaud, D. M.; Preudhomme, M. A.; Jurg, M.; Smith, M. K.; Buckley, H.; Tarnas, J.; Chalumeau, C.; Lombard-Poirot, N.; Mann, B.
As the closest Earth-like, potentially life-sustaining planet in the solar system, Mars' future of human exploration is more a question of timing than possibility. The Martian surface remains hostile, but its subsurface geology holds promise for present or ancient astrobiology and future habitation, specifically lava tube (pyroduct) systems, whose presence has been confirmed by HiRISE imagery.The location and characterization of these systems could provide a basis for understanding the evolution of the red planet and long-term shelters for future manned missions on Mars. To detect and analyze the subsurface geology of terrestrial bodies from orbit, a novel compact (smallsat-scale) and cost-effective approach called the High-resolution Orbiter for Mapping gEology by Radar (HOMER) has been proposed. Adapting interferometry techniques with synthetic aperture radar (SAR) to a ground penetrating radar system, a small satellite constellation is able to achieve a theoretical resolution of 50m from low-Mars orbit (LMO). Alongside this initial prototype design of HOMER, proposed data processing methodology and software and a Mars mission design are presented. This project was developed as part of the 2015 NASA Ames Academy for Space Exploration.
Features of Propagation of the Acoustic-Gravity Waves Generated by High-Power Periodic Radiation
NASA Astrophysics Data System (ADS)
Chernogor, L. F.; Frolov, V. L.
We present the results of the bandpass filtering of temporal variations of the Doppler frequency shift of radio signals from a vertical-sounding Doppler radar located near the city of Kharkov when the ionosphere was heated by high-power periodic (with 10 and 15-min periods) radiation from the Sura facility. The filtering was done in the ranges of periods that are close to the acoustic cutoff period and the Brunt—Väisälä period (4-6, 8-12, and 13-17 min). Oscillations with periods of 4-6 min and amplitudes of 50-100 mHz were not recorded in fact. Oscillations with periods of 8-12 and 13-17 min and amplitudes of 60-100 mHz were detected in almost all the sessions. In the former and the latter oscillations, the time of delay with respect to the heater switch-on was close to 100 min and about 40-50 min, respectively. These values correspond to group propagation velocities of about 160 and 320-400 m/s. The Doppler shift oscillations were caused by the acoustic-gravity waves which led to periodic variations in the electron number density with a relative amplitude of about 0.1-1.0%. It was demonstrated that the acoustic-gravity waves were not recorded when the effective power of the Sura facility was equal to 50 MW and they were confidently observed when the effective power was increased up to 130 MW. It is shown that the period of the wave processes was determined by the period of the heating-pause cycles, and the duration of the wave trains did not depend on the duration of the series of heating-pause cycles. The data suggest that the generation mechanism of recorded wave disturbances is different from the mechanism proposed in 1970-1990.
The endocrine dyscrasia that accompanies menopause and andropause induces aberrant cell cycle signaling that triggers re-entry of post-mitotic neurons into the cell cycle, neurodysfunction, neurodegeneration and cognitive disease.
Atwood, Craig S; Bowen, Richard L
the activation of Cdk5, a key regulator of cell cycle progression and tau phosphorylation (a cardinal feature of both neurogenesis and neurodegeneration). Cognitive and biochemical studies confirm the negative consequences of a high LH:sex steroid ratio on dendritic spine density and human cognitive performance. Prospective epidemiological and clinical evidence in humans supports the premise that rebalancing the ratio of circulating gonadotropins:sex steroids reduces the incidence of AD. Together, these data support endocrine dyscrasia and the subsequent loss of cell cycle control as an important etiological event in the development of neurodegenerative diseases including AD, stroke and Parkinson's disease.
Quantitative analysis of anthropogenic relief features: automated mapping of charcoal kiln sites from high-resolution ALS data
NASA Astrophysics Data System (ADS)
Schneider, Anna; Takla, Melanie; Nicolay, Alexander; Raab, Alexandra; Raab, Thomas
High-resolution digital elevation data from airborne laser scanning (ALS) allow for identification and mapping of so far unknown small-scale relief features that are hidden by forest cover. Especially as a result of historic land use, small anthropogenic landforms can occur, e.g., remains of charcoal kilns on sites that were used for charcoal production or ridge and furrow systems in former farmland areas. Mapping such relief features and analyzing their spatial distribution patterns can help to understand past land-use systems and their effects on landscapes. To efficiently detect and quantify small-scale relief features from high-resolution DEMs for larger areas, (semi-) automated mapping routines are required. In order to describe the number and spatial distribution of historic charcoal kiln sites in the area around Cottbus, Germany, we developed a GIS-based routine for the detection and mapping of kiln remnants from ALS elevation models with a resolution of 1 or 2 meters. The method is based on a template matching algorithm, using a combination of morphometric parameters, and is implemented within ArcGIS. The mapping results could be validated against a comprehensive database of kiln sites and diameters recorded from archaeological excavations in the forefield of the opencast mine Jänschwalde and from manual digitization of kiln remnants from Shaded Relief maps for the Jänschwalder Heide and the Tauersche Forst, north of Cottbus. A considerably high number of charcoal kiln sites could be detected in ALS data, and the diameters of the identified charcoal kilns are remarkable large in the area. For the Jänschwalder Heide, more than 5000 kiln sites in an area of 32 km2 were detected by manual digitization, with 1355 kiln sites that are wider than 12 m. These relatively large kiln sites could be mapped with detection rates that are close to those of manual digitization using the automated mapping routine. Detection quality was improved by the combination of
Mitotic and meiotic chromosome studies in silky anteater Cyclopes didactylus (Myrmecophagidae: Xenarthra).
Jorge, W
The karyotype of a male pigmy anteater, Cyclopes didactylus, an endangered species from the Amazon region, is described. The size and morphology of the X and Y chromosomes in mitotic and meiotic analyses is recorded and discussed.
Selective extraction of isolated mitotic apparatus. Evidence that typical microtubule protein is extracted by organic mercurial.
Bibring, T; Baxandall, J
Mitotic apparatus isolated from sea urchin eggs has been treated with meralluride sodium under conditions otherwise resembling those of its isolation. The treatment causes a selective morphological disappearance of microtubules while extracting a major protein fraction, probably consisting of two closely related proteins, which constitutes about 10% of mitotic apparatus protein. Extraction of other cell particulates under similar conditions yields much less of this protein. The extracted protein closely resembles outer doublet microtubule protein from sea urchin sperm tail in properties considered typical of microtubule proteins: precipitation by calcium ion and vinblastine, electrophoretic mobility in both acid and basic polyacrylamide gels, sedimentation coefficient, molecular weight, and, according to a preliminary determination, amino acid composition. An antiserum against a preparation of sperm tail outer doublet microtubules cross-reacts with the extract from mitotic apparatus. On the basis of these findings it appears that microtubule protein is selectively extracted from isolated mitotic apparatus by treatment with meralluride, and is a typical microtubule protein.
Phosphorylation of Lte1 by Cdk prevents polarized growth during mitotic arrest in S. cerevisiae
Spanos, Adonis; Jensen, Sanne; Sedgwick, Steven G.
Lte1 is known as a regulator of mitotic progression in budding yeast. Here we demonstrate phosphorylation-dependent inhibition of polarized bud growth during G2/M by Lte1. Cla4 activity first localizes Lte1 to the polarity cap and thus specifically to the bud. This localization is a prerequisite for subsequent Clb–Cdk-dependent phosphorylation of Lte1 and its relocalization to the entire bud cortex. There, Lte1 interferes with activation of the small GTPases, Ras and Bud1. The inhibition of Bud1 prevents untimely polarization until mitosis is completed and Cdc14 phosphatase is released. Inhibition of Bud1 and Ras depends on Lte1's GEF-like domain, which unexpectedly inhibits these small G proteins. Thus, Lte1 has dual functions for regulation of mitotic progression: it both induces mitotic exit and prevents polarized growth during mitotic arrest, thereby coupling cell cycle progression and morphological development. PMID:21149565
Suspension of mitotic activity in dentate gyrus of the hibernating ground squirrel.
Popov, Victor I; Kraev, Igor V; Ignat'ev, Dmitri A; Stewart, Michael G
Neurogenesis occurs in the adult mammalian hippocampus, a region of the brain important for learning and memory. Hibernation in Siberian ground squirrels provides a natural model to study mitosis as the rapid fall in body temperature in 24 h (from 35-36°C to +4-6°C) permits accumulation of mitotic cells at different stages of the cell cycle. Histological methods used to study adult neurogenesis are limited largely to fixed tissue, and the mitotic state elucidated depends on the specific phase of mitosis at the time of day. However, using an immunohistochemical study of doublecortin (DCX) and BrdU-labelled neurons, we demonstrate that the dentate gyrus of the ground squirrel hippocampus contains a population of immature cells which appear to possess mitotic activity. Our data suggest that doublecortin-labelled immature cells exist in a mitotic state and may represent a renewable pool for generation of new neurons within the dentate gyrus.
Human mitotic chromosomes consist predominantly of irregularly folded nucleosome fibres without a 30-nm chromatin structure
Nishino, Yoshinori; Eltsov, Mikhail; Joti, Yasumasa; Ito, Kazuki; Takata, Hideaki; Takahashi, Yukio; Hihara, Saera; Frangakis, Achilleas S; Imamoto, Naoko; Ishikawa, Tetsuya; Maeshima, Kazuhiro
How a long strand of genomic DNA is compacted into a mitotic chromosome remains one of the basic questions in biology. The nucleosome fibre, in which DNA is wrapped around core histones, has long been assumed to be folded into a 30-nm chromatin fibre and further hierarchical regular structures to form mitotic chromosomes, although the actual existence of these regular structures is controversial. Here, we show that human mitotic HeLa chromosomes are mainly composed of irregularly folded nucleosome fibres rather than 30-nm chromatin fibres. Our comprehensive and quantitative study using cryo-electron microscopy and synchrotron X-ray scattering resolved the long-standing contradictions regarding the existence of 30-nm chromatin structures and detected no regular structure >11 nm. Our finding suggests that the mitotic chromosome consists of irregularly arranged nucleosome fibres, with a fractal nature, which permits a more dynamic and flexible genome organization than would be allowed by static regular structures. PMID:22343941
A Fine-Structure Map of Spontaneous Mitotic Crossovers in the Yeast Saccharomyces cerevisiae
Lee, Phoebe S.; Greenwell, Patricia W.; Dominska, Margaret; Gawel, Malgorzata; Hamilton, Monica; Petes, Thomas D.
Homologous recombination is an important mechanism for the repair of DNA damage in mitotically dividing cells. Mitotic crossovers between homologues with heterozygous alleles can produce two homozygous daughter cells (loss of heterozygosity), whereas crossovers between repeated genes on non-homologous chromosomes can result in translocations. Using a genetic system that allows selection of daughter cells that contain the reciprocal products of mitotic crossing over, we mapped crossovers and gene conversion events at a resolution of about 4 kb in a 120-kb region of chromosome V of Saccharomyces cerevisiae. The gene conversion tracts associated with mitotic crossovers are much longer (averaging about 12 kb) than the conversion tracts associated with meiotic recombination and are non-randomly distributed along the chromosome. In addition, about 40% of the conversion events have patterns of marker segregation that are most simply explained as reflecting the repair of a chromosome that was broken in G1 of the cell cycle. PMID:19282969
Dimerization of TRAF-interacting protein (TRAIP) regulates the mitotic progression.
Park, I Seul; Jo, Ku-Sung; Won, Hyung-Sik; Kim, Hongtae
The homo- or hetero-dimerization of proteins plays critical roles in the mitotic progression. The TRAF-interacting protein (TRAIP) is crucial in early mitotic progression and chromosome alignment defects in the metaphase. The TRAIP is a 469 amino acid protein, including the Really Interesting New Gene (RING), coiled-coil (CC), and leucine zipper (LZ) domain. In general, the CC or LZ domain containing proteins forms homo- or hetero-dimerization to achieve its activity. In this study, a number of TRAIP mutants were used to define the TRAIP molecular domains responsible for its homo-dimerization. A co-immunoprecipitation assay indicated that the TRAIP forms homo-dimerization through the CC domain. The cells, expressing the CC domain-deleted mutant that could not form a homo-dimer, increased the mitotic index and promoted mitotic progression.
Anti-mitotic agents: Are they emerging molecules for cancer treatment?
Penna, Larissa Siqueira; Henriques, João Antonio Pêgas; Bonatto, Diego
Mutations in cancer cells frequently result in cell cycle alterations that lead to unrestricted growth compared to normal cells. Considering this phenomenon, many drugs have been developed to inhibit different cell-cycle phases. Mitotic phase targeting disturbs mitosis in tumor cells, triggers the spindle assembly checkpoint and frequently results in cell death. The first anti-mitotics to enter clinical trials aimed to target tubulin. Although these drugs improved the treatment of certain cancers, and many anti-microtubule compounds are already approved for clinical use, severe adverse events such as neuropathies were observed. Since then, efforts have been focused on the development of drugs that also target kinases, motor proteins and multi-protein complexes involved in mitosis. In this review, we summarize the major proteins involved in the mitotic phase that can also be targeted for cancer treatment. Finally, we address the activity of anti-mitotic drugs tested in clinical trials in recent years.
Poleward microtubule flux mitotic spindles assembled in vitro
In the preceding paper we described pathways of mitotic spindle assembly in cell-free extracts prepared from eggs of Xenopus laevis. Here we demonstrate the poleward flux of microtubules in spindles assembled in vitro, using a photoactivatable fluorescein covalently coupled to tubulin and multi-channel fluorescence videomicroscopy. After local photoactivation of fluorescence by UV microbeam, we observed poleward movement of fluorescein-marked microtubules at a rate of 3 microns/min, similar to rates of chromosome movement and spindle elongation during prometaphase and anaphase. This movement could be blocked by the addition of millimolar AMP-PNP but was not affected by concentrations of vanadate up to 150 microM, suggesting that poleward flux may be driven by a microtubule motor similar to kinesin. In contrast to previous results obtained in vivo (Mitchison, T. J. 1989. J. Cell Biol. 109:637-652), poleward flux in vitro appears to occur independently of kinetochores or kinetochore microtubules, and therefore may be a general property of relatively stable microtubules within the spindle. We find that microtubules moving towards poles are dynamic structures, and we have estimated the average half-life of fluxing microtubules in vitro to be between approximately 75 and 100 s. We discuss these results with regard to the function of poleward flux in spindle movements in anaphase and prometaphase. PMID:1999464
Physical Description of Mitotic Spindle Orientation During Cell Division
NASA Astrophysics Data System (ADS)
Jiménez-Dalmaroni, Andrea; Théry, Manuel; Racine, Victor; Bornens, Michel; Jülicher, Frank
During cell division, the duplicated chromosomes are physically separated by the action of the mitotic spindle. The spindle is a dynamic structure of the cytoskeleton, which consists of two microtubule asters. Its orientation defines the axis along which the cell divides. Recent experiments show that the spindle orientation depends on the spatial distribution of cell adhesion sites. Here we show that the experimentally observed spindle orientation can be understood as the result of the action of cortical force generators acting on the spindle. We assume that the local activity of force generators is controlled by the spatial distribution of cell adhesion sites determined by the particular geometry of the adhesive substrate. We develop a simple physical description of the spindle mechanics, which allows us to calculate the torque acting on the spindle, as well as the energy profile and the angular distribution of spindle orientation. Our model accounts for the preferred spindle orientation, as well as the full shape of the angular distributions of spindle orientation observed in a large variety of pattern geometries. M. Th'ery, A. Jim'enez-Dalmaroni, et al., Nature 447, 493 (2007).
Mitotic abnormalities leading to cancer predisposition and progression.
Cavenee, W K
The development of human cancer is generally thought to entail a series of events that cause a progressively more malignant phenotype. Such a hypothesis predicts that tumor cells of the ultimate stage will carry each of the events, cells of the penultimate stage will carry each of the events less the last one, and so on. That is to say a dissection of the pathway from a normal cell to a fully malignant tumor may be viewed as the unraveling of a nested set of aberrations. In experiments designed to elucidate these events, we have compared genotypic combinations at genomic loci defined by restriction endonuclease recognition site variation in normal and tumor tissues from patients with various forms and stages of cancer. The first step, inherited predisposition, is best described for retinoblastoma in which a recessive mutation of a locus residing in the 13q14 region of the genome is unmasked by aberrant, but specific, mitotic chromosomal segregation. A similar mechanism involving the distal short arm of chromosome 17 is apparent in astrocytic tumors and the event is shared by cells in each malignancy stage. This is distinct from a loss of heterozygosity for loci on chromosome 10 which is restricted to the ultimate stage, glioblastoma multiforme. These results suggest a genetic approach to defining degrees of tumor progression and means for determining the genomic locations of genes involved in the pathway as a prelude to their molecular isolation and characterization.
Control of the mitotic exit network during meiosis.
Attner, Michelle A; Amon, Angelika
The mitotic exit network (MEN) is an essential GTPase signaling pathway that triggers exit from mitosis in budding yeast. We show here that during meiosis, the MEN is dispensable for exit from meiosis I but contributes to the timely exit from meiosis II. Consistent with a role for the MEN during meiosis II, we find that the signaling pathway is active only during meiosis II. Our analysis further shows that MEN signaling is modulated during meiosis in several key ways. Whereas binding of MEN components to spindle pole bodies (SPBs) is necessary for MEN signaling during mitosis, during meiosis MEN signaling occurs off SPBs and does not require the SPB recruitment factor Nud1. Furthermore, unlike during mitosis, MEN signaling is controlled through the regulated interaction between the MEN kinase Dbf20 and its activating subunit Mob1. Our data lead to the conclusion that a pathway essential for vegetative growth is largely dispensable for the specialized meiotic divisions and provide insights into how cell cycle regulatory pathways are modulated to accommodate different modes of cell division.
The Prp19 complex directly functions in mitotic spindle assembly.
Hofmann, Jennifer C; Tegha-Dunghu, Justus; Dräger, Stefanie; Will, Cindy L; Lührmann, Reinhard; Gruss, Oliver J
The conserved Prp19 (pre-RNA processing 19) complex is required for pre-mRNA splicing in eukaryotic nuclei. Recent RNAi screens indicated that knockdown of Prp19 complex subunits strongly delays cell proliferation. Here we show that knockdown of the smallest subunit, BCAS2/Spf27, destabilizes the entire complex and leads to specific mitotic defects in human cells. These could result from splicing failures in interphase or reflect a direct function of the complex in open mitosis. Using Xenopus extracts, in which cell cycle progression and spindle formation can be reconstituted in vitro, we tested Prp19 complex functions during a complete cell cycle and directly in open mitosis. Strikingly, immunodepletion of the complex either before or after interphase significantly reduces the number of intact spindles, and increases the percentage of spindles with lower microtubule density and impaired metaphase alignment of chromosomes. Our data identify the Prp19 complex as the first spliceosome subcomplex that directly contributes to mitosis in vertebrates independently of its function in interphase.
Maintaining Genome Stability in Defiance of Mitotic DNA Damage
Ferrari, Stefano; Gentili, Christian
The implementation of decisions affecting cell viability and proliferation is based on prompt detection of the issue to be addressed, formulation and transmission of a correct set of instructions and fidelity in the execution of orders. While the first and the last are purely mechanical processes relying on the faithful functioning of single proteins or macromolecular complexes (sensors and effectors), information is the real cue, with signal amplitude, duration, and frequency ultimately determining the type of response. The cellular response to DNA damage is no exception to the rule. In this review article we focus on DNA damage responses in G2 and Mitosis. First, we set the stage describing mitosis and the machineries in charge of assembling the apparatus responsible for chromosome alignment and segregation as well as the inputs that control its function (checkpoints). Next, we examine the type of issues that a cell approaching mitosis might face, presenting the impact of post-translational modifications (PTMs) on the correct and timely functioning of pathways correcting errors or damage before chromosome segregation. We conclude this essay with a perspective on the current status of mitotic signaling pathway inhibitors and their potential use in cancer therapy. PMID:27493659
Detection of cyclotron resonance scattering feature in high-mass X-ray binary pulsar SMC X-2
NASA Astrophysics Data System (ADS)
Jaisawal, Gaurava K.; Naik, Sachindra
We report broad-band spectral properties of the high-mass X-ray binary pulsar SMC X-2 by using three simultaneous Nuclear Spectroscopy Telescope Array and Swift/XRT observations during its 2015 outburst. The pulsar was significantly bright, reaching a luminosity up to as high as ˜5.5 × 1038 erg s-1 in 1-70 keV range. Spin period of the pulsar was estimated to be 2.37 s. Pulse profiles were found to be strongly luminosity dependent. The 1-70 keV energy spectrum of the pulsar was well described with three different continuum models such as (i) negative and positive power law with exponential cutoff, (ii) Fermi-Dirac cutoff power law and (iii) cutoff power-law models. Apart from the presence of an iron line at ˜6.4 keV, a model independent absorption like feature at ˜27 keV was detected in the pulsar spectrum. This feature was identified as a cyclotron absorption line and detected for the first time in this pulsar. Corresponding magnetic field of the neutron star was estimated to be ˜2.3 × 1012 G. The cyclotron line energy showed a marginal negative dependence on the luminosity. The cyclotron line parameters were found to be variable with pulse phase and interpreted as due to the effect of emission geometry or complicated structure of the pulsar magnetic field.
High performance organic integrated device with ultraviolet photodetective and electroluminescent properties consisting of a charge-transfer-featured naphthalimide derivative
Wang, Hanyu; Wang, Xu; Yu, Junsheng E-mail: firstname.lastname@example.com; Zhou, Jie; Lu, Zhiyun E-mail: email@example.com
A high performance organic integrated device (OID) with ultraviolet photodetective and electroluminescent (EL) properties was fabricated by using a charge-transfer-featured naphthalimide derivative of 6-(3,5-bis-[9-(4-t-butylphenyl)-9H-carbazol-3-yl]-phenoxy)-2- (4-t-butylphenyl)-benzo[de]isoquinoline-1,3-dione (CzPhONI) as the active layer. The results showed that the OID had a high detectivity of 1.5 × 10{sup 11} Jones at −3 V under the UV-350 nm illumination with an intensity of 0.6 mW/cm{sup 2}, and yielded an exciplex EL light emission with a maximum brightness of 1437 cd/m{sup 2}. Based on the energy band diagram, both the charge transfer feature of CzPhONI and matched energy level alignment were responsible for the dual ultraviolet photodetective and EL functions of OID.
High-quality and small-capacity e-learning video featuring lecturer-superimposing PC screen images
NASA Astrophysics Data System (ADS)
Nomura, Yoshihiko; Murakami, Michinobu; Sakamoto, Ryota; Sugiura, Tokuhiro; Matsui, Hirokazu; Kato, Norihiko
Information processing and communication technology are progressing quickly, and are prevailing throughout various technological fields. Therefore, the development of such technology should respond to the needs for improvement of quality in the e-learning education system. The authors propose a new video-image compression processing system that ingeniously employs the features of the lecturing scene. While dynamic lecturing scene is shot by a digital video camera, screen images are electronically stored by a PC screen image capturing software in relatively long period at a practical class. Then, a lecturer and a lecture stick are extracted from the digital video images by pattern recognition techniques, and the extracted images are superimposed on the appropriate PC screen images by off-line processing. Thus, we have succeeded to create a high-quality and small-capacity (HQ/SC) video-on-demand educational content featuring the advantages: the high quality of image sharpness, the small electronic file capacity, and the realistic lecturer motion.
High-risk angina patient: identification by clinical features, hospital course, electrocardiography, and technetium-99m stannous pyrophosphate scintigraphy
Olson, H.G.; Lyons, K.P.; Aronow, W.S.; Stinson, P.J.; Kuperus, J.; Waters, H.J.
We evaluated 193 consecutive unstable angina patients by clinical features, hospital course and electrocardiography. All patients were managed medically. Of the 193 patients, 150 (78%) had a technetium-99m pyrophosphate (Tc-PYP) myocardial scintigram after hospitalization. Of these, 49 (33%) had positive scintigrams. At a follow-up of 24.9 +- 10.8 months after hospitalization, 16 of 49 patients (33%) with positive scintigrams died from cardiac causes, compared with six of 101 patients (6%) with negative scintigrams (p < 0.001). Of 49 patients with positive scintigrams, 11 (22%) had had nonfatal myocardial infarction at follow-up, compared with seven of 101 patients (7%) with negative scintigrams (p < 0.01). Age, duration of clinical coronary artery disease, continuing angina during hospitalization, ischemic ECG, cardiomegaly and a history of heart failure also correlated with cardiac death at follow-up. Ischemic ECG and a history of angina with a crescendo pattern also correlated with nonfatal infarction at follow-up. Patients with continuing angina, an ischemic ECG and a positive scintigram constituted a high-risk unstable angina subgroup, with a survival rate of 58% at 6 months, 47% at 12 months and 42% at 24 and 36 months. We conclude that the assessment of clinical features, hospital course, ECG and Tc-PYP scintigraphy may be useful in identifying high-risk unstable angina patients.
High-risk angina patient. Identification by clinical features, hospital course, electrocardiography and technetium-99m stannous pyrophosphate scintigraphy
Olson, H.G.; Lyons, K.P.; Aronow, W.S.; Stinson, P.J.; Kuperus, J.; Waters, H.J.
We evaluated 193 consecutive unstable angina patients by clinical features, hospital course and electrocardiography. All patients were managed medically. Of the 193 patients, 150 (78%) had a technetium-99m pyrophosphate (Tc-PYP) myocardial scintigram after hospitalization. Of these, 49 (33%) had positive scintigrams. At a follow-up of 24.9 +/- 10.8 months after hospitalization, 16 of 49 patients (33%) with positive scintigrams died from cardiac causes, compared with six of 101 patients (6%) with negative scintigrams (p less than 0.001). Of 49 patients with positive scintigrams, 11 (22%) had had nonfatal myocardial infarction at follow-up, compared with seven of 101 patients (7%) with negative scintigrams (p less than 0.01). Age, duration of clinical coronary artery disease, continuing angina during hospitalization, ischemic ECG, cardiomegaly and a history of heart failure also correlated with cardiac death at follow-up. Ischemic ECG and a history of angina with a crescendo pattern also correlated with nonfatal infarction at follow-up. Patients with continuing angina, an ischemic ECG and a positive scintigram constituted a high-risk unstable angina subgroup with a survival rate of 58% at 6 months, 47% at 12 months and 42% at 24 and 36 months. We conclude that the assessment of clinical features, hospital course, ECG and Tc-PYP scintigraphy may be useful in identifying high-risk unstable angina patients.
Atmospheric-water absorption features near 2.2 micrometers and their importance in high spectral resolution remote sensing
NASA Technical Reports Server (NTRS)
Kruse, F. A.; Clark, R. N.
Selective absorption of electromagnetic radiation by atmospheric gases and water vapor is an accepted fact in terrestrial remote sensing. Until recently, only a general knowledge of atmospheric effects was required for analysis of remote sensing data; however, with the advent of high spectral resolution imaging devices, detailed knowledge of atmospheric absorption bands has become increasingly important for accurate analysis. Detailed study of high spectral resolution aircraft data at the U.S. Geological Survey has disclosed narrow absorption features centered at approximately 2.17 and 2.20 micrometers not caused by surface mineralogy. Published atmospheric transmission spectra and atmospheric spectra derived using the LOWTRAN-5 computer model indicate that these absorption features are probably water vapor. Spectral modeling indicates that the effects of atmospheric absorption in this region are most pronounced in spectrally flat materials with only weak absorption bands. Without correction and detailed knowledge of the atmospheric effects, accurate mapping of surface mineralogy (particularly at low mineral concentrations) is not possible.
Independence-oriented VMD to identify fault feature for wheel set bearing fault diagnosis of high speed locomotive
NASA Astrophysics Data System (ADS)
Li, Zipeng; Chen, Jinglong; Zi, Yanyang; Pan, Jun
As one of most critical component of high-speed locomotive, wheel set bearing fault identification has attracted an increasing attention in recent years. However, non-stationary vibration signal with modulation phenomenon and heavy background noise make it difficult to excavate the hidden weak fault feature. Variational Mode Decomposition (VMD), which can decompose the non-stationary signal into couple Intrinsic Mode Functions adaptively and non-recursively, brings a feasible tool. However, heavy background noise seriously affects setting of mode number, which may lead to information loss or over decomposition problem. In this paper, an independence-oriented VMD method via correlation analysis is proposed to adaptively extract weak and compound fault feature of wheel set bearing. To overcome the information loss problem, the appropriate mode number is determined by the criterion of approximate complete reconstruction. Then the similar modes are combined according to the similarity of their envelopes to solve the over decomposition problem. Finally, three applications to wheel set bearing fault of high speed locomotive verify the effectiveness of the proposed method compared with original VMD, EMD and EEMD methods.
Rhn1, a nuclear protein, is required for suppression of meiotic mRNAs in mitotically dividing fission yeast.
Sugiyama, Tomoyasu; Sugioka-Sugiyama, Rie; Hada, Kazumasa; Niwa, Ryusuke
In the fission yeast Schizosaccharomyces pombe, many meiotic mRNAs are transcribed during mitosis and meiosis and selectively eliminated in mitotic cells. However, this pathway for mRNA decay, called the determinant of selective removal (DSR)-Mmi1 system, targets only some of the numerous meiotic mRNAs that are transcribed in mitotic cells. Here we describe Rhn1, a nuclear protein involved in meiotic mRNA suppression in vegetative fission yeast. Rhn1 is homologous to budding yeast Rtt103 and localizes to one or a few discrete nuclear dots in growing vegetative cells. Rhn1 colocalizes with a pre-mRNA 3'-end processing factor, Pcf11, and with the 5'-3' exoribonuclease, Dhp1; moreover, Rhn1 coimmunoprecipitates with Pcf11. Loss of rhn1 results in elevated sensitivity to high temperature, to thiabendazole (TBZ), and to UV. Interestingly, meiotic mRNAs--including moa1(+), mcp5(+), and mug96(+)--accumulate in mitotic rhn1Δ cells. Accumulation of meiotic mRNAs also occurs in strains lacking Lsk1, a kinase that phosphorylates serine 2 (Ser-2) in the C-terminal domain (CTD) of RNA polymerase II (Pol II), and in strains lacking Sen1, an ATP-dependent 5'-3' RNA/DNA helicase: notably, both Lsk1 and Sen1 have been implicated in termination of Pol II-dependent transcription. Furthermore, RNAi knockdown of cids-2, a Caenorhabditis elegans ortholog of rhn1(+), leads to elevated expression of a germline-specific gene, pgl-1, in somatic cells. These results indicate that Rhn1 contributes to the suppression of meiotic mRNAs in vegetative fission yeast and that the mechanism by which Rhn1 downregulates germline-specific transcripts may be conserved in unicellular and multicellular organisms.
Role of p53 codon 72 polymorphism in chromosomal aberrations and mitotic index in patients with chronic hepatitis B.
Akbaş, H; Yalcin, K; Isi, H; Tekes, S; Atay, A E; Akkus, Z; Budak, T
Polymorphisms of the p53 gene, which participates in DNA repair, can affect the functioning of the p53 protein. The Arg and Pro variants in p53 codon 72 were shown to have different regulation properties of p53-dependent DNA repair target genes that can affect various levels of cytogenetic aberrations in chronic hepatitis B patients. The present study aimed to examine the frequency of chromosomal aberrations and the mitotic index in patients with chronic hepatitis B and their possible association with p53 gene exon 4 codon 72 Arg72Pro (Ex4+119 G>C; rs1042522) polymorphism. Fifty-eight patients with chronic hepatitis B and 30 healthy individuals were genotyped in terms of the p53 gene codon 72 Arg72Pro polymorphism by PCR-RFLP. A 72-h cell culture was performed on the same individuals and evaluated in terms of chromosomal aberrations and mitotic index. A high frequency of chromosomal aberrations and low mitotic index were detected in the patient group compared to the control group. A higher frequency of chromosomal aberrations was detected in both the patient and the control groups with a homozygous proline genotype (13 patients, 3 control subjects) compared to patients and controls with other genotypes [Arg/Pro (38 patients, 20 control subjects) and Arg/Arg (7 patients, 7 control subjects)]. We observed an increased frequency of cytogenetic aberrations in patients with chronic hepatitis B. In addition, a higher frequency of cytogenetic aberrations was observed in p53 variants having the homozygous proline genotype compared to variants having other genotypes both in patients and healthy individuals.
New spectral features of stratospheric trace gases identified from high-resolution infrared balloon-borne and laboratory spectra
NASA Technical Reports Server (NTRS)
Goldman, A.; Murcray, F. J.; Blatherwick, R. D.; Kosters, J. J.; Murcray, F. H.; Murcray, D. G.; Rinsland, C. P.
A new Michelson-type interferometer system operating in the infrared at very high resolution has been used to record numerous balloon-borne solar absorption spectra of the stratosphere, ground-based solar absorption spectra, and laboratory spectra of molecules of atmospheric interest. In the present work results obtained for several important stratospheric trace gases, HNO3, CIONO2, HO2NO2, NO2, and COF2, in the 8- to 12-micron spectral region are reported. Many new features of these gases have been identified in the stratospheric spectra. Comparison of the new spectra with line-by-line simulations shows that previous spectral line parameters are often inadequate and that new analysis of high-resolution laboratory and atmospheric spectra and improved theoretical calculations will be required for many bands. Preliminary versions of several sets of improved line parameters under development are discussed.
An Efficient Method for Dorsal Root Ganglia Neurons Purification with a One-Time Anti-Mitotic Reagent Treatment
Liu, Rui; Lin, Gou; Xu, Hanpeng
Background The dorsal root ganglia (DRG) neuron is an invaluable tool in axon growth, growth factor regulation, myelin formation and myelin-relevant researches. The purification of DRG neurons is a key step in these studies. Traditionally, purified DRG neurons were obtained in two weeks after exposure to several rounds of anti-mitotic reagent. Methods and Results In this report, a novel, simple and efficient method for DRG purification is presented. DRG cultures were treated once with a high-dose anti-mitotic reagent cocktail for 72 hours. Using this new method, DRG neurons were obtained with 99% purification within 1 week. We confirmed that the neurite growth and the viability of the purified DRG neurons have no difference from the DRG neurons purified by traditional method. Furthermore, P0 and MBP expression was observed in myelin by immunocytochemistry in the DRG/SC co-culture system. The formation of mature node of Ranvier in DRG-Schwann cell co-culture system was observed using anti-Nav 1.6 and anti-caspr antibody. Conclusion and Significance The results indicate that this high dose single treatment did not compromise the capacity of DRG neurons for myelin formation in the DRG/SC co-culture system. In conclusion, a convenient approach for purifying DRG neurons was developed which is time-saving and high-efficiency. PMID:23565257
Effects of polyamines and polyamine biosynthetic inhibitors on mitotic activity of Allium cepa root tips.
Unal, Meral; Palavan-Unsal, Narcin; Tufekci, M A
The genotoxic and cytotoxic effects of exogenous polyamines (PAs), putrescine (Put), spermidine (Spd), spermine (Spm) and PA biosynthetic inhibitors, alpha-difluoromethylornithine (DFMO), cyclohexilamine (CHA), methylglioxal bis-(guanylhydrazone) (MGBG) were investigated in the root meristems of Allium cepa L. The reduction of mitotic index and the induction of chromosomal aberrations such as bridges, stickiness, c-mitotic anaphases, micronuclei, endoredupliction by PAs and PA biosynthetic inhibitors were observed and these were used as evidence of genotoxicity and cytotoxicity.
Mitotic cells form actin-based bridges with adjacent cells to provide intercellular communication during rounding.
Fykerud, Tone A; Knudsen, Lars M; Totland, Max Z; Sørensen, Vigdis; Dahal-Koirala, Shiva; Lothe, Ragnhild A; Brech, Andreas; Leithe, Edward
In order to achieve accurate chromosome segregation, eukaryotic cells undergo a dramatic change in morphology to obtain a spherical shape during mitosis. Interphase cells communicate directly with each other by exchanging ions and small molecules via gap junctions, which have important roles in controlling cell growth and differentiation. As cells round up during mitosis, the gap junctional communication between mitotic cells and adjacent interphase cells ceases. Whether mitotic cells use alternative mechanisms for mediating direct cell-cell communication during rounding is currently unknown. Here, we have studied the mechanisms involved in the remodeling of gap junctions during mitosis. We further demonstrate that mitotic cells are able to form actin-based plasma membrane bridges with adjacent cells during rounding. These structures, termed "mitotic nanotubes," were found to be involved in mediating the transport of cytoplasm, including Rab11-positive vesicles, between mitotic cells and adjacent cells. Moreover, a subpool of the gap-junction channel protein connexin43 localized in these intercellular bridges during mitosis. Collectively, the data provide new insights into the mechanisms involved in the remodeling of gap junctions during mitosis and identify actin-based plasma membrane bridges as a novel means of communication between mitotic cells and adjacent cells during rounding.
XAB2 functions in mitotic cell cycle progression via transcriptional regulation of CENPE
Hou, Shuai; Li, Na; Zhang, Qian; Li, Hui; Wei, Xinyue; Hao, Tian; Li, Yue; Azam, Sikandar; Liu, Caigang; Cheng, Wei; Jin, Bilian; Liu, Quentin; Li, Man; Lei, Haixin
Xeroderma pigmentosum group A (XPA)-binding protein 2 (XAB2) is a multi-functional protein that plays critical role in processes including transcription, transcription-coupled DNA repair, pre-mRNA splicing, homologous recombination and mRNA export. Microarray analysis on gene expression in XAB2 knockdown cells reveals that many genes with significant change in expression function in mitotic cell cycle regulation. Fluorescence-activated cell scanner analysis confirmed XAB2 depletion led to cell arrest in G2/M phase, mostly at prophase or prometaphase. Live cell imaging further disclosed that XAB2 knockdown induced severe mitotic defects including chromosome misalignment and defects in segregation, leading to mitotic arrest, mitotic catastrophe and subsequent cell death. Among top genes down-regulated by XAB2 depletion is mitotic motor protein centrosome-associated protein E (CENPE). Knockdown CENPE showed similar phenotypes to loss of XAB2, but CENPE knockdown followed by XAB2 depletion did not further enhance cell cycle arrest. Luciferase assay on CENPE promoter showed that overexpression of XAB2 increased luciferase activity, whereas XAB2 depletion resulted in striking reduction of luciferase activity. Further mapping revealed a region in CENPE promoter that is required for the transcriptional regulation by XAB2. Moreover, ChIP assay showed that XAB2 interacted with CENPE promoter. Together, these results support a novel function of XAB2 in mitotic cell cycle regulation, which is partially mediated by transcription regulation on CENPE. PMID:27735937
Phosphorylation of XIAP by CDK1–cyclin-B1 controls mitotic cell death
Hou, Ying; Allan, Lindsey A.
ABSTRACT Regulation of cell death is crucial for the response of cancer cells to drug treatments that cause arrest in mitosis, and is likely to be important for protection against chromosome instability in normal cells. Prolonged mitotic arrest can result in cell death by activation of caspases and the induction of apoptosis. Here, we show that X-linked inhibitor of apoptosis (XIAP) plays a key role in the control of mitotic cell death. Ablation of XIAP expression sensitises cells to prolonged mitotic arrest caused by a microtubule poison. XIAP is stable during mitotic arrest, but its function is controlled through phosphorylation by the mitotic kinase CDK1–cyclin-B1 at S40. Mutation of S40 to a phosphomimetic residue (S40D) inhibits binding to activated effector caspases and abolishes the anti-apoptotic function of XIAP, whereas a non-phosphorylatable mutant (S40A) blocks apoptosis. By performing live-cell imaging, we show that phosphorylation of XIAP reduces the threshold for the onset of cell death in mitosis. This work illustrates that mitotic cell death is a form of apoptosis linked to the progression of mitosis through control by CDK1–cyclin-B1. PMID:27927753
Mitotic cells form actin-based bridges with adjacent cells to provide intercellular communication during rounding
Fykerud, Tone A.; Knudsen, Lars M.; Totland, Max Z.; Dahal-Koirala, Shiva; Lothe, Ragnhild A.; Brech, Andreas; Leithe, Edward
ABSTRACT In order to achieve accurate chromosome segregation, eukaryotic cells undergo a dramatic change in morphology to obtain a spherical shape during mitosis. Interphase cells communicate directly with each other by exchanging ions and small molecules via gap junctions, which have important roles in controlling cell growth and differentiation. As cells round up during mitosis, the gap junctional communication between mitotic cells and adjacent interphase cells ceases. Whether mitotic cells use alternative mechanisms for mediating direct cell-cell communication during rounding is currently unknown. Here, we have studied the mechanisms involved in the remodeling of gap junctions during mitosis. We further demonstrate that mitotic cells are able to form actin-based plasma membrane bridges with adjacent cells during rounding. These structures, termed "mitotic nanotubes," were found to be involved in mediating the transport of cytoplasm, including Rab11-positive vesicles, between mitotic cells and adjacent cells. Moreover, a subpool of the gap-junction channel protein connexin43 localized in these intercellular bridges during mitosis. Collectively, the data provide new insights into the mechanisms involved in the remodeling of gap junctions during mitosis and identify actin-based plasma membrane bridges as a novel means of communication between mitotic cells and adjacent cells during rounding. PMID:27625181
The Mitotic Checkpoint Gene, SIL is Regulated by E2F1
Erez, Ayelet; Chaussepied, Marie; Tina, Colaizzo-Anas; Aplan, Peter; Ginsberg, Doron; Izraeli, Shai
The SIL gene expression is increased in multiple cancers and correlates with the expression of mitotic spindle checkpoint genes and with increased metastatic potential. SIL regulates mitotic entry, organization of the mitotic spindle and cell survival. The E2F transcription factors regulate cell cycle progression by controlling the expression of genes mediating the G1/S transition. More recently E2F has been shown to regulate mitotic spindle checkpoint genes as well. As SIL expression correlates with mitotic checkpoint genes we hypothesized that SIL is regulated by E2F. We mined raw data of published experiments and performed new experiments by modification of E2F expression in cell lines, reporter assays and chromatin immunoprecipitation. Ectopic expression or endogenous activation of E2F induced the expression of SIL, while knockdown of E2F by shRNA, downregulated SIL expression. E2F activated SIL promoter by reporter assay and bound to SIL promoter in-vivo. Taken together these data demonstrate that SIL is regulated by E2F. As SIL is essential for mitotic entry, E2F may regulate G2/M transition through the induction of SIL. Furthermore, as silencing of SIL cause apoptosis in cancer cells, these finding may have therapeutic relevance in tumors with constitutive activation of E2F. PMID:18649360
The FlyCatwalk: A High-Throughput Feature-Based Sorting System for Artificial Selection in Drosophila
Medici, Vasco; Vonesch, Sibylle Chantal; Fry, Steven N.; Hafen, Ernst
Experimental evolution is a powerful tool for investigating complex traits. Artificial selection can be applied for a specific trait and the resulting phenotypically divergent populations pool-sequenced to identify alleles that occur at substantially different frequencies in the extreme populations. To maximize the proportion of loci that are causal to the phenotype among all enriched loci, population size and number of replicates need to be high. These requirements have, in fact, limited evolution studies in higher organisms, where the time investment required for phenotyping is often prohibitive for large-scale studies. Animal size is a highly multigenic trait that remains poorly understood, and an experimental evolution approach may thus aid in gaining new insights into the genetic basis of this trait. To this end, we developed the FlyCatwalk, a fully automated, high-throughput system to sort live fruit flies (Drosophila melanogaster) based on morphometric traits. With the FlyCatwalk, we can detect gender and quantify body and wing morphology parameters at a four-old higher throughput compared with manual processing. The phenotyping results acquired using the FlyCatwalk correlate well with those obtained using the standard manual procedure. We demonstrate that an automated, high-throughput, feature-based sorting system is able to avoid previous limitations in population size and replicate numbers. Our approach can likewise be applied for a variety of traits and experimental settings that require high-throughput phenotyping. PMID:25556112
The FlyCatwalk: a high-throughput feature-based sorting system for artificial selection in Drosophila.
Medici, Vasco; Vonesch, Sibylle Chantal; Fry, Steven N; Hafen, Ernst
Experimental evolution is a powerful tool for investigating complex traits. Artificial selection can be applied for a specific trait and the resulting phenotypically divergent populations pool-sequenced to identify alleles that occur at substantially different frequencies in the extreme populations. To maximize the proportion of loci that are causal to the phenotype among all enriched loci, population size and number of replicates need to be high. These requirements have, in fact, limited evolution studies in higher organisms, where the time investment required for phenotyping is often prohibitive for large-scale studies. Animal size is a highly multigenic trait that remains poorly understood, and an experimental evolution approach may thus aid in gaining new insights into the genetic basis of this trait. To this end, we developed the FlyCatwalk, a fully automated, high-throughput system to sort live fruit flies (Drosophila melanogaster) based on morphometric traits. With the FlyCatwalk, we can detect gender and quantify body and wing morphology parameters at a four-old higher throughput compared with manual processing. The phenotyping results acquired using the FlyCatwalk correlate well with those obtained using the standard manual procedure. We demonstrate that an automated, high-throughput, feature-based sorting system is able to avoid previous limitations in population size and replicate numbers. Our approach can likewise be applied for a variety of traits and experimental settings that require high-throughput phenotyping.
High-resolution PFPE-based molding techniques for nanofabrication of high-pattern density, sub-20 nm features: a fundamental materials approach.
Williams, Stuart S; Retterer, Scott; Lopez, Rene; Ruiz, Ricardo; Samulski, Edward T; DeSimone, Joseph M
Several perfluoropolyether (PFPE)-based elastomers for high-resolution replica molding applications are explored. The modulus of the elastomeric materials was increased through synthetic and additive approaches while maintaining relatively low surface tension values (<25 mN/m). Using large area (>4 in.(2)) master templates, we experimentally show the relationship between mold resolution and material properties such as modulus and surface tension for materials used in this study. A composite mold approach was used to form flexible molds out of stiff, high modulus materials that allow for replication of sub-20 nm post structures. Sub-100 nm line grating master templates, formed using e-beam lithography, were used to determine the experimental stability of the molding materials. It was observed that as the feature spacing decreased, high modulus PFPE tetramethacrylate (TMA) composite molds were able to effectively replicate the nanograting structures without cracking or tear-out defects that typically occur with high modulus elastomers.
Expression of Fibroblast Activating Protein and Correlation with Histological Grade, Mitotic Index and Ki67 Expression in Canine Mast Cell Tumours.
Giuliano, A; Dos Santos Horta, R; Constantino-Casas, F; Hoather, T; Dobson, J
Fibroblast activating protein (FAP) is a membrane serine protease expressed by activated fibroblasts, particularly tumour associated fibroblasts (TAFs). FAP expression has not been reported in canine mast cell tumours (MCTs). The objective of this study was to evaluate the expression of FAP in TAFs and its correlation with histological grade, mitotic index and Ki67 expression in canine MCTs. FAP expression was evaluated by immunohistochemistry (IHC) in 30 canine MCTs. Twenty-eight (90%) of the MCTs expressed FAP in the stroma, 16 cases showed low to intermediate FAP score and 14 cases had a high FAP score. FAP was correlated positively with both Patnaik (P = 0.007) and Kiupel (P = 0.008) grading systems, mitotic index (P = 0.0008) and Ki67 expression (P = 0.009). High stromal FAP expression could be a potential negative prognostic factor in canine MCTs.
Design features of first of its kind AFBC high pressure boiler for Kutch lignite fuel in Gujarat, India
Diwakar, K.K.; Mokashi, A.H.
Gujarat Heavy Chemicals Limited (GHCL) in Gujarat State in India is one of the largest manufacturers of Soda Ash with modern most technology from Akzo of Neitherland. GHCL with earlier experience of firing of kind of lignite on travagrate boiler and with converted fluidized bed boiler has very clearly identified the problem areas for review and with that rich experience awarded contract to Thermax Babcock and Wilcox Limited (TBW), Pune, India a joint venture company of Thermax Limited, Pune, India and Babcock and Wilcox, USA. Accordingly, boiler has been designed to suit Kutch Lignite and Coal with AFBC Technology, Single Drum Design, top supported with underbed feeding system. Capacity of boiler is 90 Ton/Hr with design pressure of 130 kg/cm{sup 2} with superheated steam temperature of 510 C. This is the first boiler in India with such a high pressure and temperature conditions for this capacity firing lignite. Other first of its kind features include single drum boiler convection bank made with headers and tubes, riffled inbed evaporator tubes, erosion protection by surface coating and not by studs, line bed system for inert material, no soot blowers, specially designed double hinged SS supports for inbed superheater coils etc. This boiler also has a provision of over fire air arrangement for better combustion split. Other unique features include the start-up arrangement by HSD burners which can take the boiler up to 30% load, provision for flue gas recirculation system, specially designed SS air distribution nozzles, separate compartments for under feed, ash drain and air cooled distribution plate with 1:5 turndown. The paper discusses all the above design features.
Novel Mad2-targeting miR-493-3p controls mitotic fidelity and cancer cells' sensitivity to paclitaxel
Mäki-Jouppila, Jenni; Chen, Ping; Elgaaen, Bente Vilming; Straume, Anne Hege; Huhtinen, Kaisa; Cárpen, Olli; Lønning, Per Eystein; Davidson, Ben; Hautaniemi, Sampsa; Kallio, Marko J.
The molecular pathways that contribute to the proliferation and drug response of cancer cells are highly complex and currently insufficiently characterized. We have identified a previously unknown microRNA-based mechanism that provides cancer cells means to stimulate tumorigenesis via increased genomic instability and, at the same time, evade the action of clinically utilized microtubule drugs. We demonstrate miR-493-3p to be a novel negative regulator of mitotic arrest deficient-2 (MAD2), an essential component of the spindle assembly checkpoint that monitors the fidelity of chromosome segregation. The microRNA targets the 3′ UTR of Mad2 mRNA thereby preventing translation of the Mad2 protein. In cancer cells, overexpression of miR-493-3p induced a premature mitotic exit that led to increased frequency of aneuploidy and cellular senescence in the progeny cells. Importantly, excess of the miR-493-3p conferred resistance of cancer cells to microtubule drugs. In human neoplasms, miR-493-3p and Mad2 expression alterations correlated with advanced ovarian cancer forms and high miR-493-3p levels were associated with reduced survival of ovarian and breast cancer patients with aggressive tumors, especially in the paclitaxel therapy arm. Our results suggest that intratumoral profiling of miR-493-3p and Mad2 levels can have diagnostic value in predicting the efficacy of taxane chemotherapy. PMID:26943585
Location of 45S Ribosomal Genes in Mitotic and Meiotic Chromosomes of Buthid Scorpions.
Mattos, Viviane Fagundes; Carvalho, Leonardo Sousa; Cella, Doralice Maria; Schneider, Marielle Cristina
Buthid scorpions exhibit a high variability in diploid number within genera and even within species. Cytogenetically, Buthidae differs from other families of Scorpiones based on its low diploid numbers, holocentric chromosomes, and complex chromosomal chains, which form during meiosis. In this study, we analyzed the distribution of the 45S ribosomal DNA (rDNA) genes in the mitotic and meiotic chromosomes of seven buthid species belonging to the genera Rhopalurus and Tityus with the ultimate goal of elucidating the chromosome organization in these scorpions. The chromosome number ranged from 2n=6 to 2n=28. Despite the high variance in diploid number, all species examined carried their 45S rDNA sites in the terminal region of exactly two chromosomes. Analyses of meiotic cells revealed 45S rDNA clusters in the chromosomal chains of Rhopalurus agamemnon, Tityus bahiensis, Tityus confluens, and Tityus martinpaechi, or in bivalent-like configuration in Rhopalurus rochai, Tityus bahiensis, Tityus confluens, Tityus fasciolatus, and Tityus paraguayensis. In the species examined, the 45S rDNA sites colocalized with constitutive heterochromatin regions. In light of the high chromosome variability and maintenance of number and terminal position of 45S rDNA sites in buthids, the heterochromatin may act to conserve the integrity of the ribosomal genes.
Highly Water-Stable Novel Lanthanide Wheel Cluster Organic Frameworks Featuring Coexistence of Hydrophilic Cagelike Chambers and Hydrophobic Nanosized Channels.
Zhou, Yuan-Yuan; Shi, Yang; Geng, Bing; Bo, Qi-Bing
In attempts to investigate the potential luminescent sensing materials for sensitive detection of environmental pollutants, a new family of lanthanide wheel cluster organic frameworks (Ln-WCOFs) UJN-Ln4 has been constructed by employing one of the cycloalkane dicarboxylic acid derivatives. Adopting different conformations, the ligand links Ln4 second building units (SBUs) and Ln24 tertiary building units (TBUs) to form a unique wheel cluster layer-pillared 3D framework featuring the coexistence of hydrophobic nanosized channels and trigonal antiprism arrays with hydrophilic cagelike chambers. Apart from charming structures, isostructural UJN-Ln4 displays interesting porous, water-stable features. Systematic luminescence studies demonstrate that solvent water molecules can enhance the emission intensity of solid-state UJN-Eu4. Acting as a recyclable luminescent probe, water-stable luminescent UJN-Eu4 exhibits superior "turn-off" detection for Fe(3+) and Cu(2+) ions in aqueous solutions. Due to the nanosized hydrophobic channels, UJN-Eu4 also shows highly sensitive sensing of sodium dodecyl benzenesulfonate (SDBS) via luminescence "turn-on" respondence, representing the first example of quantitatively detecting SDBS in aqueous solutions by employing luminescent lanthanide frameworks as fluorescent sensors. The results also open up the exploration of novel luminescent Ln-WCOFs exhibiting unique applications in sensitive detecting of harmful pollutants in aquatic environments.
High resolution transmission electron microscope Imaging and first-principles simulations of atomic-scale features in graphene membrane
NASA Astrophysics Data System (ADS)
Wang, Wei; Bhandari, Sagar; Yi, Wei; Bell, David; Westervelt, Robert; Kaxiras, Efthimios
Ultra-thin membranes such as graphene[1] are of great importance for basic science and technology applications. Graphene sets the ultimate limit of thinness, demonstrating that a free-standing single atomic layer not only exists but can be extremely stable and strong [2--4]. However, both theory [5, 6] and experiments [3, 7] suggest that the existence of graphene relies on intrinsic ripples that suppress the long-wavelength thermal fluctuations which otherwise spontaneously destroy long range order in a two dimensional system. Here we show direct imaging of the atomic features in graphene including the ripples resolved using monochromatic aberration-corrected transmission electron microscopy (TEM). We compare the images observed in TEM with simulated images based on an accurate first-principles total potential. We show that these atomic scale features can be mapped through accurate first-principles simulations into high resolution TEM contrast. [1] Geim, A. K. & Novoselov, K. S. Nat. Mater. 6, 183-191, (2007). [2] Novoselov, K. S.et al. Science 306, 666-669, (2004). [3] Meyer, J. C. et al. Nature 446, 60-63, (2007). [4] Lee, C., Wei, X. D., Kysar, J. W. & Hone, J. Science 321, 385-388, (2008). [5] Nelson, D. R. & Peliti, L. J Phys-Paris 48, 1085-1092, (1987). [6] Fasolino, A., Los, J. H. & Katsnelson, M. I. Nat. Mater. 6, 858-861, (2007). [7] Meyer, J. C. et al. Solid State Commun. 143, 101-109, (2007).
The co-evolution of microstructure features in self-ion irradiated HT9 at very high damage levels
NASA Astrophysics Data System (ADS)
Getto, E.; Vancoevering, G.; Was, G. S.
precipitates to understand the effect on either voids or dislocations. Finally, a more complete combination of microstructure treatments will be implemented to determine if any discrepancies between the model and experiment can be resolved. Thus, the objective of this paper is to understand the co-evolution of microstructure features at very high damage in self-ion irradiated HT9 using a rate theory model to unfold the interactions between the major irradiated microstructure features.
A new method to decide the practical feature of Fresnel lens from the result of ultra-high refractive index method (Conference Presentation)
NASA Astrophysics Data System (ADS)
Shibuya, Masato; Hiramatsu, Takashi; Araki, Keisuke; Nakadate, Suezou; Fujii, Junki
We propose a new method to decide the brazed feature of Fresnel lens from the result of high refractive index method. Traditionally the feature has been designed to satisfy the phase-difference function for a point object by having brazed surface relieves only on one side of the lens. Therefore the exit ray of the practical feature is different from that of high-index method even for this point object. Thus the aberration is changed. To solve this problem, we propose Fresnel lens having brazed feature on both sides. Studying the spherical Fresnel lens which collects sun light, we theoretically show how to decide the shape. Also by practical lens designing, we demonstrate the validity of our theory. The proposed method is useful to decide the brazed feature of Fresnel lens from the result of high refractive index method, especially for small view angle lenses.
Design features of first of its kind AFBC high pressure boiler for Kutch lignite fuel in Gujarat, India
Mokashi, A.; Diwakar, K.W.
Gujarat Heavy Chemicals Ltd. (GHCL) of Gujarat State in India is one of the largest manufacturers of Soda Ash with modern technology from Akzo of the Netherlands. GHCL with earlier experience in firing lignite on a travagrate boiler and with a converted fluidized bed boiler has very clearly identified the problem area for review, and with that rich experience awarded a contract to Thermax Babcock and Wilcox Ltd. (TBW), Pune, India. Accordingly, a boiler has been designed to suit Kutch Lignite and coal with AFBC technology. This paper discusses the complete design of the boiler, effects of Kutch Lignite, its composition, thermal efficiency on coal as well as lignite, various performance parameters and guarantees, sizing arrangements of pressure parts, feeding arrangement and specially designed fluidizing bed combustor, various instrumentation and control loops. This paper discusses all the above features of this high-pressure boiler which can be an ideal boiler for the Kutch lignite fuel.
EAM-based high-speed 100-km OFDM transmission featuring tolerant modulator operation enabled using SSII cancellation.
Chen, Hsing-Yu; Wei, Chia-Chien; Lu, I-Cheng; Chen, Yu-Chao; Chu, Hsuan-Hao; Chen, Jyehong
In this study, a technique was developed to compensate for nonlinear distortion through cancelling subcarrier-to-subcarrier intermixing interference (SSII) in an electroabsorption modulator (EAM)-based orthogonal frequency-division multiplexing (OFDM) transmission system. The nonlinear distortion to be compensated for is induced by both EAM nonlinearity and fiber dispersion. Because an OFDM signal features an inherently high peak-to-average power ratio, a trade-off exists between the optical modulation index (OMI) and modulator nonlinearity. Therefore, the nonlinear distortion limits the operational tolerance of the bias voltage and the driving power to a small region. After applying the proposed SSII cancellation, the OMI of an OFDM signal was increased yielding only a small increment of nonlinear distortion, and the tolerance region of the operational conditions was also increased. By employing the proposed scheme, this study successfully demonstrates 50-Gbps OFDM transmission over 100-km dispersion-uncompensated single-mode fiber based on a single 10-GHz EAM.
Features of the Jovian DAM radiation dynamic spectra as observed by modern receivers with high frequency-temporal resolution
NASA Astrophysics Data System (ADS)
Litvinenko, G.; Konovalenko, A.; Zakharenko, V.; Vinogradov, V.; Shaposhnikov, V.; Zarka, Ph.
One of the promising approaches to investigating features of the Jovian decameter radio emission (DAM) is application of novel experimental techniques with a further detailed analysis of the obtained data using both well-known and modern mathematical methods. Several observational campaigns were performed in November 2009 with the use of the UTR-2 radio telescope (Kharkov, Ukraine) and efficient registration systems with high frequency and temporal resolutions (the antenna effective area is about 105 m2, the frequency resolution is 4 kHz, the temporal resolution is 0.25 ms, and the dynamic range is 70 dB) [1]. The main goal of these campaigns was to experimentally investigate new properties of the Jovian DAM emission which could be detected using the above mentioned equipment. Also an original software package was developed for control the digital receiver and for off-line data analysis at the postprocessing stage.
Analogues to features and processes of a high-level radioactive waste repository proposed for Yucca Mountain, Nevada
Simmons, Ardyth M.; Stuckless, John S.; with a Foreword by Abraham Van Luik, U.S. Department of Energy
Natural analogues are defined for this report as naturally occurring or anthropogenic systems in which processes similar to those expected to occur in a nuclear waste repository are thought to have taken place over time periods of decades to millennia and on spatial scales as much as tens of kilometers. Analogues provide an important temporal and spatial dimension that cannot be tested by laboratory or field-scale experiments. Analogues provide one of the multiple lines of evidence intended to increase confidence in the safe geologic disposal of high-level radioactive waste. Although the work in this report was completed specifically for Yucca Mountain, Nevada, as the proposed geologic repository for high-level radioactive waste under the U.S. Nuclear Waste Policy Act, the applicability of the science, analyses, and interpretations is not limited to a specific site. Natural and anthropogenic analogues have provided and can continue to provide value in understanding features and processes of importance across a wide variety of topics in addressing the challenges of geologic isolation of radioactive waste and also as a contribution to scientific investigations unrelated to waste disposal. Isolation of radioactive waste at a mined geologic repository would be through a combination of natural features and engineered barriers. In this report we examine analogues to many of the various components of the Yucca Mountain system, including the preservation of materials in unsaturated environments, flow of water through unsaturated volcanic tuff, seepage into repository drifts, repository drift stability, stability and alteration of waste forms and components of the engineered barrier system, and transport of radionuclides through unsaturated and saturated rock zones.
Clinicopathological Features of Triple Negative Breast Carcinoma
Reddy, Gowry Maram; Pai, Radha R.
Introduction Breast carcinoma is one of the most common malignancies affecting women in developing countries. Molecular studies of breast carcinoma have classified the tumour based on the immunohistochemical staining into 4 subtypes, such as Luminal A, Luminal B, HER2/neu Positive and Triple Negative Breast Carcinoma (TNBC). TNBCs are reported to have an aggressive behaviour and wide metastasis, leading to selective treatment outcomes. Aim The aim was to study the clinicopathological features such as age, site, tumour size, histopathological type, histologic grade, lymph node status, stage and treatment outcomes of triple negative breast carcinoma. Materials and Methods A retrospective study was conducted on 108 cases of breast carcinoma received during the period of 2 years. The tumour was classified based on immunohistochemical staining into four subtypes. The clinicopathological details, histomorphological and immunohistochemical features of TNBC were studied. Results Of the 108 patients, 34 patients were diagnosed as TNBC. The average age at presentation was 48 years. Most of the cases showed Nottingham Modification of Scarff Bloom-Richardson (NMBR) grade 3 (55.9%) and stage II (67.6%). Ly-mph node metastasis was seen in 50% of cases. Infiltrating ductal carcinoma (not otherwise specified) type (91.2%) was the most common histological type. Among the other subtypes, Luminal A carcinoma was the most common (36.1%), followed by TNBC (31.5%) and HER2/neu positive carcinomas (28.7%). Compared to the other types of tumours, TNBC showed the most frequent distant lymph node metastasis (50%) when compared to luminal A (38.5%), luminal B (25%), HER2/neu positive (48.4%). Unlike the other types of tumours, TNBC were mostly high-grade. Conclusion TNBC have an aggressive behaviour compared to other subtypes with higher NMBR grade, nuclear pleomorphism, high mitotic rate and lymph node metastasis. PMID:28273970
Investigation on particle swarm optimisation for feature selection on high-dimensional data: local search and selection bias
NASA Astrophysics Data System (ADS)
Tran, Binh; Xue, Bing; Zhang, Mengjie; Nguyen, Su
Feature selection is an essential step in classification tasks with a large number of features, such as in gene expression data. Recent research has shown that particle swarm optimisation (PSO) is a promising approach to feature selection. However, it also has potential limitation to get stuck into local optima, especially for gene selection problems with a huge search space. Therefore, we developed a PSO algorithm (PSO-LSRG) with a fast "local search" combined with a gbest resetting mechanism as a way to improve the performance of PSO for feature selection. Furthermore, since many existing PSO-based feature selection approaches on the gene expression data have feature selection bias, i.e. no unseen test data is used, 2 sets of experiments on 10 gene expression datasets were designed: with and without feature selection bias. As compared to standard PSO, PSO with gbest resetting only, and PSO with local search only, PSO-LSRG obtained a substantial dimensionality reduction and a significant improvement on the classification performance in both sets of experiments. PSO-LSRG outperforms the other three algorithms when feature selection bias exists. When there is no feature selection bias, PSO-LSRG selects the smallest number of features in all cases, but the classification performance is slightly worse in a few cases, which may be caused by the overfitting problem. This shows that feature selection bias should be avoided when designing a feature selection algorithm to ensure its generalisation ability on unseen data.