what cell process in controlled by the nucleus
regulating gene expression
77538
way to promote cell function. The nucleus maintains the integrity of genes and controls the activities of the cell by regulating gene expression—the nucleus is, therefore, the control center of the cell. The main structures making up the nucleus are the nuclear envelope, a double membrane that encloses the entire organelle and isolates its contents from the cellular cytoplasm, and the nuclear matrix (which includes the nuclear lamina), a network within the nucleus that adds mechanical support, much like the cytoskeleton, which supports the cell as a whole. Because the nuclear envelope is impermeable to large molecules, nuclear pores are
Cell nucleus
77572
transcribed, the cell separates some transcription factor proteins responsible for regulating gene expression from physical access to the DNA until they are activated by other signaling pathways. This prevents even low levels of inappropriate gene expression. For example, in the case of NF-κB-controlled genes, which are involved in most inflammatory responses, transcription is induced in response to a signal pathway such as that initiated by the signaling molecule TNF-α, binds to a cell membrane receptor, resulting in the recruitment of signalling proteins, and eventually activating the transcription factor NF-κB. A nuclear localisation signal on the NF-κB protein allows it to
Cell nucleus
77538
way to promote cell function. The nucleus maintains the integrity of genes and controls the activities of the cell by regulating gene expression—the nucleus is, therefore, the control center of the cell. The main structures making up the nucleus are the nuclear envelope, a double membrane that encloses the entire organelle and isolates its contents from the cellular cytoplasm, and the nuclear matrix (which includes the nuclear lamina), a network within the nucleus that adds mechanical support, much like the cytoskeleton, which supports the cell as a whole. Because the nuclear envelope is impermeable to large molecules, nuclear pores are
Cell nucleus
77584
microtubules come in contact with chromosomes, whose centromeric regions are incorporated into the nuclear envelope (the so-called closed mitosis with extranuclear spindle). In many other protists (e.g., ciliates, sporozoans) and fungi, the centrosomes are intranuclear, and their nuclear envelope also does not disassemble during cell division. Apoptosis is a controlled process in which the cell's structural components are destroyed, resulting in death of the cell. Changes associated with apoptosis directly affect the nucleus and its contents, for example, in the condensation of chromatin and the disintegration of the nuclear envelope and lamina. The destruction of the lamin networks is controlled
Cell nucleus
77577
encode different protein sequences. This process is known as alternative splicing, and allows production of a large variety of proteins from a limited amount of DNA. The entry and exit of large molecules from the nucleus is tightly controlled by the nuclear pore complexes. Although small molecules can enter the nucleus without regulation, macromolecules such as RNA and proteins require association karyopherins called importins to enter the nucleus and exportins to exit. "Cargo" proteins that must be translocated from the cytoplasm to the nucleus contain short amino acid sequences known as nuclear localization signals, which are bound by importins, while
Cell nucleus
112552
the cell cycle; DNA replication takes place during the S phase (synthesis phase). The progress of the eukaryotic cell through the cycle is controlled by cell cycle checkpoints. Progression through checkpoints is controlled through complex interactions between various proteins, including cyclins and cyclin-dependent kinases. Unlike bacteria, eukaryotic DNA replicates in the confines of the nucleus. The G1/S checkpoint (or restriction checkpoint) regulates whether eukaryotic cells enter the process of DNA replication and subsequent division. Cells that do not proceed through this checkpoint remain in the G0 stage and do not replicate their DNA. Replication of chloroplast and mitochondrial genomes occurs
DNA replication
15228438
located on one side of the dividing somatic nucleus are distributed to one daughter cell, and the somatic chromosomes on the other side of the nucleus are distributed to the other daughter cell. This amitotic process causes the two daughter cells to potentially have identical germ-line nucleus but a different somatic nucleus in regards to the copy numbers of the chromosomes. As the somatic nucleus is the nucleus that is transcriptionally active, this somatic copy number mutation derived by the amitotic process could have fitness consequences for the individual cell. "Childonella uncinata" is easily cultured in the laboratory, has a
Chilodonella uncinata
262326
generation system that renders the parasite resistant to many classical mitochondrial inhibitors such as cyanide, azide, and atovaquone. Mitochondria divide by binary fission, similar to bacterial cell division. The regulation of this division differs between eukaryotes. In many single-celled eukaryotes, their growth and division is linked to the cell cycle. For example, a single mitochondrion may divide synchronously with the nucleus. This division and segregation process must be tightly controlled so that each daughter cell receives at least one mitochondrion. In other eukaryotes (in mammals for example), mitochondria may replicate their DNA and divide mainly in response to the energy
Mitochondrion
3197254
rectum sphincters remain normal even during the final terminal stages of the illness. Since these muscles are controlled by Onuf's nucleus, it is of great importance in the study of this disease. In amyotrophic lateral sclerosis, Onuf's nucleus is preserved but the other anterior horn cell groups atrophy. This discovery reinforced the notion that Onuf's nucleus controlled the muscles related to sphincter function in the anus and urethra. In a study conducted by Kihira et al., eight individuals with amyotrophic lateral sclerosis were compared to nine control cases. The results indicated that the total number of neurons in Onuf's nucleus
Onuf's nucleus
77586
to proteins inside the nucleus in order to replicate and/or assemble. DNA viruses, such as herpesvirus replicate and assemble in the cell nucleus, and exit by budding through the inner nuclear membrane. This process is accompanied by disassembly of the lamina on the nuclear face of the inner membrane. Initially, it has been suspected that immunoglobulins in general and autoantibodies in particular do not enter the nucleus. Now there is a body of evidence that under pathological conditions (e.g. lupus erythematosus) IgG can enter the nucleus. Most eukaryotic cell types usually have a single nucleus, but some have no nuclei,
Cell nucleus
77580
a protein due to incomplete excision of exons or mis-incorporation of amino acids could have negative consequences for the cell; thus, incompletely modified RNA that reaches the cytoplasm is degraded rather than used in translation. During its lifetime, a nucleus may be broken down or destroyed, either in the process of cell division or as a consequence of apoptosis (the process of programmed cell death). During these events, the structural components of the nucleus — the envelope and lamina — can be systematically degraded. In most cells, the disassembly of the nuclear envelope marks the end of the prophase of
Cell nucleus
20128109
from a cell. The most known example is the enucleation process of erythrocytes. A processed stem cell goes through changes causing it to lose a nucleus. In the beginning phase, pro-erythroblast goes through another mitotic divisions, in which an erythroblast with a smaller nucleus is created and moved to the side of the cell. The nucleus becomes isolated from cytoplasm and then erythroblast is divided into reticulocyte with cytoplasm and pyrenocyte with condensed nucleus. Pyrenocyte with all genetic material from cell is degraded then by a macrophage. Loss of genome is in this case advantageous, since pyrenocyte can accumulate more
Somatic genome processing
19931433
breakthrough in scientific discovery. Known as somatic cell nuclear transfer, this process involves removing the nucleus of a regular body cell and implanting that nucleus into an egg cell that has had its cell nucleus removed. A nucleus is the organelle that holds a cell's genetic material (its DNA). Campbell and Wilmut found that if the donor, somatic cell is arrested in the stage of the cell cycle where it is dormant and non-replicating (the quiescent phase) prior to nuclear transfer, the resulting fused cell will develop into an embryo. The resulting cloned animal is an exact genetic replica of
In Re Roslin Institute (Edinburgh)
4553189
The central cell in the curve of the hook contains one A and one a nucleus (see Figure). This binuclear cell initiates ascus formation and is called an “ascus-initial” cell. Next the two uninucleate cells on either side of the first ascus-forming cell fuse with each other to form a binucleate cell that can grow to form a further crozier that can then form its own ascus-initial cell. This process can then be repeated multiple times. After formation of the ascus-initial cell, the A and a nucleus fuse with each other to form a diploid nucleus (see Figure). This nucleus
Heterothallism
3178478
egg cell, forming a zygote, while the other sperm nucleus usually fuses with the binucleate central cell, forming a primary endosperm cell (its nucleus is often called the "triple fusion nucleus"). That cell created in the process of double fertilization develops into the endosperm. Because it is formed by a separate fertilization, the endosperm constitutes an organism separate from the growing embryo. About 70% of angiosperm species have endosperm cells that are polyploid. These are typically triploid (containing three sets of chromosomes), but can vary widely from diploid (2n) to 15n. One species of flowering plant, "Nuphar polysepala", has been
Endosperm
1451395
nucleus of the donor egg cell is removed and discarded, leaving it 'deprogrammed.' What is left is a somatic cell and an denucleated egg cell. These are then fused by inserting the somatic cell into the 'empty' ovum. After being inserted into the egg, the somatic cell nucleus is reprogrammed by its host egg cell. The ovum, now containing the somatic cell's nucleus, is stimulated with a shock and will begin to divide. The egg is now viable and capable of producing an adult organism containing all the necessary genetic information from just one parent. Development will ensue normally and
Somatic cell nuclear transfer
77582
in open mitosis, the cell divides to form two cells. In order for this process to be possible, each of the new daughter cells must have a full set of genes, a process requiring replication of the chromosomes as well as segregation of the separate sets. This occurs by the replicated chromosomes, the sister chromatids, attaching to microtubules, which in turn are attached to different centrosomes. The sister chromatids can then be pulled to separate locations in the cell. In many cells, the centrosome is located in the cytoplasm, outside the nucleus; the microtubules would be unable to attach to
Cell nucleus
957466
be controlled, for example by the introduction or removal of neutron absorbers. This is what allows nuclear reactors to be built. Fast neutrons are not easily captured by nuclei; they must be slowed (slow neutrons), generally by collision with the nuclei of a neutron moderator, before they can be easily captured. Today, this type of fission is commonly used to generate electricity. If nuclei are forced to collide, they can undergo nuclear fusion. This process may release or absorb energy. When the resulting nucleus is lighter than that of iron, energy is normally released; when the nucleus is heavier than
Nuclear technology
9314444
being developed to treat people with genetic disorders in an experimental medical technique called gene therapy. However, here the new gene is put in after the person has grown up and become ill, so any new gene is not inherited by their children. Gene therapy works by trying to replace the allele that causes the disease with an allele that works properly. Introduction to genetics Genetics is the study of heredity and variations. Heredity and variations are controlled by genes—what they are, what they do, and how they work. Genes inside the nucleus of a cell are strung together in
Introduction to genetics
77587
while others have several. This can result from normal development, as in the maturation of mammalian red blood cells, or from faulty cell division. An anucleated cell contains no nucleus and is, therefore, incapable of dividing to produce daughter cells. The best-known anucleated cell is the mammalian red blood cell, or erythrocyte, which also lacks other organelles such as mitochondria, and serves primarily as a transport vessel to ferry oxygen from the lungs to the body's tissues. Erythrocytes mature through erythropoiesis in the bone marrow, where they lose their nuclei, organelles, and ribosomes. The nucleus is expelled during the process
Cell nucleus
15228436
complementary, the germ-line nucleus undergoes meiosis to produce zygotic nuclei. Each conjugated cell transfers one zygotic nucleus to the other cell where the zygotic nuclei fuse. The diploid germ-line nucleus undergoes mitosis which creates a duplicated germ-line nucleus. At this point the somatic nucleus is being degraded. The duplicated germ-line nucleus then develops into the new somatic nucleus. The genomic structure of the somatic nucleus is being created by chromosomal fragmentation with single-gene chromosomes and amplification of these somatic chromosomes. It is unknown what determines the copy number of each chromosome or if the copy number of the somatic chromosomes
Chilodonella uncinata
9314415
Introduction to genetics Genetics is the study of heredity and variations. Heredity and variations are controlled by genes—what they are, what they do, and how they work. Genes inside the nucleus of a cell are strung together in such a way that the sequence carries information: that information determines how living organisms inherit various features (phenotypic traits). For example, offspring produced by sexual reproduction usually look similar to each of their parents because they have inherited some of each of their parents' genes. Genetics identifies which features are inherited, and explains how these features pass from generation to generation. In
Introduction to genetics
83940
first to perform somatic-cell nuclear transfer using amphibian embryos – one of the first steps towards cloning. Reproductive cloning generally uses "somatic cell nuclear transfer" (SCNT) to create animals that are genetically identical. This process entails the transfer of a nucleus from a donor adult cell (somatic cell) to an egg from which the nucleus has been removed, or to a cell from a blastocyst from which the nucleus has been removed. If the egg begins to divide normally it is transferred into the uterus of the surrogate mother. Such clones are not strictly identical since the somatic cells may
Cloning
15118239
in a process known as metastasis. There are different categories of cancer cell, defined according to the cell type from which they originate. Cancer cells have distinguishing histological features visible under the microscope. The nucleus is often large and irregular, and the cytoplasm may also display abnormalities. The shape, size, protein composition, and texture of the nucleus are often altered in malignant cells. The nucleus may acquire grooves, folds or indentations, chromatin may aggregate or disperse, and the nucleolus can become enlarged. In normal cells, the nucleus is often round or ellipsoid in shape, but in cancer cells the outline
Cancer cell
79148
the prolamellar body begins to reorganize into stacks of thylakoids, and chlorophyll starts to be produced. This process, where the etioplast becomes a chloroplast, takes several hours. Gymnosperms do not require light to form chloroplasts. Light, however, does not guarantee that a proplastid will develop into a chloroplast. Whether a proplastid develops into a chloroplast some other kind of plastid is mostly controlled by the nucleus and is largely influenced by the kind of cell it resides in. Plastid differentiation is not permanent, in fact many interconversions are possible. Chloroplasts may be converted to chromoplasts, which are pigment-filled plastids responsible
Chloroplast
7855072
and break up of the chromatin into unstructured granules, and "karyolysis"; dissolution of the cell nucleus. Cytosolic components that leak through the damaged plasma membrane into the extracellular space can incur an inflammatory response. There are six types of necrosis: Apoptosis is the programmed cell death of superfluous or potentially harmful cells in the body. It is an energy dependent process mediated by proteolytic enzymes called caspases, which trigger cell death through the cleaving of specific proteins in the cytoplasm and nucleus. The dying cells shrink and condense into apoptotic bodies. The cell surface is altered so as to display
Cell damage
3932661
or heterodimer forms. Type II nuclear receptors have no HSP, and in contrast to the classical type I receptor are located in the cell nucleus. Free (that is, unbound) steroids enter the cell cytoplasm and interact with their receptor. In this process heat shock protein is dissociated, and the activated receptor-ligand complex is translocated into the nucleus. After binding to the ligand (steroid hormone), steroid receptors often form dimers. In the nucleus, the complex acts as a transcription factor, augmenting or suppressing transcription particular genes by its action on DNA. Type II receptors are located in the nucleus. Thus, their
Steroid hormone receptor
91156
to opposite sides of the cell. Mitosis occurs exclusively in eukaryotic cells, but occurs in different ways in different species. For example, animals undergo an "open" mitosis, where the nuclear envelope breaks down before the chromosomes separate, while fungi such as "Aspergillus nidulans" and "Saccharomyces cerevisiae" (yeast) undergo a "closed" mitosis, where chromosomes divide within an intact cell nucleus. Prokaryotic cells, which lack a nucleus, divide by a process called binary fission. Mitosis is immediately followed by cytokinesis, which divides the nuclei, cytoplasm, organelles and cell membrane into two cells containing roughly equal shares of these cellular components. Mitosis and
Cell cycle
20341389
old, starving worms rather than new, healthy worms. During the process of apoptosis, the cell undergoes: As a wild-type protein, ced-3 will cleave other protein substrates within the cell and trigger apoptosis. In the nucleus, ced-3 cleaves DCR-1, so that the RNA can no longer be processed, and then it converts RNase into DNase thus promoting DNA degradation in the nucleus and mitochondrial elimination in the cytoplasm. Afterwards, ced-3 indirectly releases another protein, WAH-1, that can cause signals on the surface of the cell to be released so that the cell can be phagocytosed by a neighbouring cell. In "C.
Ced-3
8811578
Nuclear transport The entry and exit of large molecules from the cell nucleus is tightly controlled by the nuclear pore complexes (NPCs). Although small molecules can enter the nucleus without regulation, macromolecules such as RNA and proteins require association with transport factors like karyopherins called importins to enter the nucleus and exportins to exit. Protein that must be imported to the nucleus from the cytoplasm carry nuclear localization signals (NLS) that are bound by importins. A NLS is a sequence of amino acids that acts as a tag. They are diverse in their composition and most commonly hydrophilic, although hydrophobic
Nuclear transport
8811584
cell with another quality control step. As described above, once the complex has crossed the envelope it dissociates and releases the tRNA cargo into the cytosol. Many proteins are known to have both NESs and NLSs and thus shuttle constantly between the nucleus and the cytosol. In certain cases one of these steps (i.e., nuclear import or nuclear export) is regulated, often by post-translational modifications. Protein shuttling can be assessed using a "heterokaryon fusion assay". Nuclear transport The entry and exit of large molecules from the cell nucleus is tightly controlled by the nuclear pore complexes (NPCs). Although small molecules
Nuclear transport
4785134
a drill is used to pierce the outer layers of the oocyte. Various chemical reagents are used to increase cloning efficiency. Microtubule inhibitors, such as nocodazole, are used to arrest the oocyte in M phase, during which its nuclear membrane is dissolved. Chemicals are also used to stimulate oocyte activation. When applied the membrane is completely dissolved. Somatic Cell Nuclear Transfer (SCNT) is the process by which the nucleus of an oocyte (egg cell) is removed and is replaced with the nucleus of a somatic (body) cell (examples include skin, heart, or nerve cell). The two entities fuse to become
Nuclear transfer
2551409
assay, so far the only test which allows the quantification of the polymerized actin directly in biological samples, have revealed that endogenous nuclear actin occurs indeed mainly in a monomeric form. Precisely controlled level of actin in the cell nucleus, lower than in the cytoplasm, prevents the formation of filaments. The polymerization is also reduced by the limited access to actin monomers, which are bound in complexes with ABPs, mainly cofilin. Little attention is paid to actin isoforms, however it has been shown that different isoforms of actin are present in the cell nucleus. Actin isoforms, despite of their high
Actin
7340694
crozier into three cells. The central cell in the curve of the hook contains one "A" and one "a" nucleus (see Figure). This binuclear cell initiates ascus formation and is called an “ascus-initial” cell. Next the two uninucleate cells on either side of the first ascus-forming cell fuse with each other to form a binucleate cell that can grow to form a further crozier that can then form its own ascus-initial cell. This process can then be repeated multiple times. After formation of the ascus-initial cell, the "A" and "a" nuclei fuse with each other to form a diploid nucleus
Mating in fungi
83929
to create cloned human beings (called "reproductive cloning"), but rather to harvest stem cells that can be used to study human development and to potentially treat disease. While a clonal human blastocyst has been created, stem cell lines are yet to be isolated from a clonal source. Therapeutic cloning is achieved by creating embryonic stem cells in the hopes of treating diseases such as diabetes and Alzheimer's. The process begins by removing the nucleus (containing the DNA) from an egg cell and inserting a nucleus from the adult cell to be cloned. In the case of someone with Alzheimer's disease,
Cloning
3521621
crozier divide synchronously. Next, septa form to divide the crozier into three cells. The central cell in the curve of the hook contains one "A" and one "a" nucleus (see Figure). This binuclear cell initiates ascus formation and is called an "ascus-initial" cell. Next the two uninucleate cells on either side of the first ascus-forming cell fuse with each other to form a binucleate cell that can grow to form a further crozier that can then form its own ascus-initial cell. This process can then be repeated multiple times. After formation of the ascus-initial cell, the "A" and "a" nucleus
Neurospora crassa
43633
the cell's DNA. This nucleus gives the eukaryote its name, which means "true kernel (nucleus)". Other differences include: All cells, whether prokaryotic or eukaryotic, have a membrane that envelops the cell, regulates what moves in and out (selectively permeable), and maintains the electric potential of the cell. Inside the membrane, the cytoplasm takes up most of the cell's volume. All cells (except red blood cells which lack a cell nucleus and most organelles to accommodate maximum space for hemoglobin) possess DNA, the hereditary material of genes, and RNA, containing the information necessary to build various proteins such as enzymes, the
Cell (biology)
20002222
large variation in α-keratin structures found in mammals. α-keratin synthesis begins near focal adhesions on the cell membrane. There, the keratin filament precursors go through a process known as nucleation, where the keratin precursors of dimers and filaments elongate, fuse, and bundles together. As this synthesis is occurring, the keratin filament precursors are transported by actin fibers in the cell towards the nucleus. There, the alpha-keratin intermediate filaments will collect and form networks of structure dictated by the use of the keratin cell as the nucleus simultaneously degrades. However, if necessary, instead of continuing to grow, the keratin complex will
Alpha-keratin
11153377
process in the nucleus that is responsible for the retention of RNAs that are defective, not yet mature enough to be exported or are designed to be retained in nucleus. NONO protein (Human) is encoded by the NONO gene which is located on the plus strand of the X chromosome. NONO has been shown to be more strongly expressed in melanoma cell lines and melanoma tissue samples compared to normal human cell lines and normal skin tissue. Studies have found that the knockout of NONO protein from melanoma cell lines results in both reduced proliferation rates of the cancer cells
NONO (protein)
7355211
etc., are normally considered to be shelf-stable, i.e. they readily inactivate a broad range of food-borne microorganisms. However, these products are still susceptible to spoilage by "Z. bailii". "Z. bailii" vegetative cells are usually ellipsoid, non-motile and reproduced asexually by multilateral budding, i.e. the buds can arise from various sites on the cells. During the budding process, a parent cell produces a bud on its outer surface. As the bud elongates, the parent cell’s nucleus divides and one nucleus migrates into the bud. Cell wall material is filled in the gap between the bud and the parent cell; eventually the
Zygosaccharomyces bailii
3190379
basophilic pronormoblast is converted from a cell with a large nucleus and a volume of 900 fL to an enucleated disc with a volume of 95 fL. By the reticulocyte stage, the cell has extruded its nucleus, but is still capable of producing hemoglobin. Essential for the maturation of red blood cells are Vitamin B (cobalamin) and Vitamin B (Folic acid). Lack of either causes maturation failure in the process of erythropoiesis, which manifests clinically as reticulocytopenia, an abnormally low amount of reticulocytes. As they mature, a number of erythrocyte characteristics change: The overall size of the erythroid precursor cell
Erythropoiesis
77574
proteins, that RNA produced from this process is messenger RNA (mRNA), which then needs to be translated by ribosomes to form a protein. As ribosomes are located outside the nucleus, mRNA produced needs to be exported. Since the nucleus is the site of transcription, it also contains a variety of proteins that either directly mediate transcription or are involved in regulating the process. These proteins include helicases, which unwind the double-stranded DNA molecule to facilitate access to it, RNA polymerases, which bind to the DNA promoter to synthesize the growing RNA molecule, topoisomerases, which change the amount of supercoiling in
Cell nucleus
2899120
briefly at M phase when the nucleus and then the cell divide in two. The process of cell division, called cell cycle, has four major parts called phases. The first part, called G phase is marked by synthesis of various enzymes that are required for DNA replication. The second part of the cell cycle is the S phase, where DNA replication produces two identical sets of chromosomes. The third part is the G phase in which a significant protein synthesis occurs, mainly involving the production of microtubules that are required during the process of division, called mitosis. The fourth phase,
Cell growth
10500888
transfer the nucleus from one cell to another and stimulate this new cell to grow and become an animal, a process known as nuclear transfer. The team at the Roslin Institute tried to make immortalized and undifferentiated embryonic stem cell lines in sheep, but failed. As a result, they decided to work with cultured blastocyst cells. The nuclear material of these blastocyst cells would be transferred into an unfertilized sheep egg cell, an oocyte where the nucleus had been removed. To optimize the chances of successful nuclear transfer, they put the cultured cells into a state of quiescence, which was
Megan and Morag
9753563
of the cytoplasm is used in the shuttling process, the more rapidly it experiences complete loss of fluorescence. The resulting image of this process should be a completely photobleached cytoplasm. If the cell also participates in nuclear export from the nucleus to the cytoplasm, photobleaching will also occur in the nucleus. The exchange rate between the nucleus and cytoplasm can also be determined from this type of data. In these instances, the region of photobleaching is within the nucleus. If shuttling occurs at a rapid pace, the fluorescence levels within the nuclear compartments will decrease rapidly through the frames taken.
Fluorescence loss in photobleaching
3849984
and actin in the apical portion of the cell which constricts as they move. The variation in cell shapes is partially determined by the location of the nucleus within the cell, causing bulging in areas of the cells forcing the height and shape of the cell to change. This process is known as apical constriction. The result is a flattening of the differentiating neural plate which is particularly obvious in salamanders when the previously round gastrula becomes a rounded ball with a flat top. See Neural plate The process of the flat neural plate folding into the cylindrical neural tube
Neurulation
629367
nucleus. Tyrosine kinase activity in the nucleus involves cell-cycle control and properties of transcription factors. In this way, in fact, tyrosine kinase activity is involved in mitogenesis, or the induction of mitosis in a cell; proteins in the cytosol and proteins in the nucleus are phosphorylated at tyrosine residues during this process. Cellular growth and reproduction may rely to some degree on tyrosine kinase. Tyrosine kinase function has been observed in the nuclear matrix, which comprises not the chromatin but rather the nuclear envelope and a “fibrous web” that serves to physically stabilize DNA. To be specific, Lyn, a type
Tyrosine kinase
91155
a spindle. The relatively brief "M phase" consists of nuclear division (karyokinesis). It is a relatively short period of the cell cycle. M phase is complex and highly regulated. The sequence of events is divided into phases, corresponding to the completion of one set of activities and the start of the next. These phases are sequentially known as: Mitosis is the process by which a eukaryotic cell separates the chromosomes in its cell nucleus into two identical sets in two nuclei. During the process of mitosis the pairs of chromosomes condense and attach to fibers that pull the sister chromatids
Cell cycle
77570
and mediate the replication of DNA during the cell cycle. The nucleus is an organelle found in eukaryotic cells. Inside its fully enclosed nuclear membrane, it contains the majority of the cell's genetic material. This material is organized as DNA molecules, along with a variety of proteins, to form chromosomes. The nuclear envelope allows the nucleus to control its contents, and separate them from the rest of the cytoplasm where necessary. This is important for controlling processes on either side of the nuclear membrane. In most cases where a cytoplasmic process needs to be restricted, a key participant is removed
Cell nucleus
77579
cytoplasm and carrying it through the nuclear pore into the nucleus. Inside the nucleus, RanGTP acts to separate the cargo from the importin, allowing the importin to exit the nucleus and be reused. Nuclear export is similar, as the exportin binds the cargo inside the nucleus in a process facilitated by RanGTP, exits through the nuclear pore, and separates from its cargo in the cytoplasm. Specialized export proteins exist for translocation of mature mRNA and tRNA to the cytoplasm after post-transcriptional modification is complete. This quality-control mechanism is important due to these molecules' central role in protein translation. Mis-expression of
Cell nucleus
12749678
that cell type. A particular gene in a cell's genome codes for the production of a particular protein, that is, when that gene is turned on (active), the protein coded for by that gene is produced and present somewhere in the cell. Production of a particular protein involves the production of a particular mRNA (messenger RNA) sequence as an intermediate step in protein synthesis. This mRNA is produced by copying process called transcription, from the DNA in the cell's nucleus. The mRNA so produced travels from the nucleus into the cytoplasm, where it encounters and latches onto ribosomes stuck to
Embryomics
4313825
nucleus. A current theory of how such survival signals are sent from axon endings to the soma includes the idea that NGF receptors are endocytosed from the surface of axon tips and that such endocytotic vesicles are transported up the axon. Soma (biology) The soma (pl. "somata" or "somas"), perikaryon (pl. "perikarya"), neurocyton, or cell body is the bulbous, non-process portion of a neuron or other brain cell type, containing the cell nucleus. The word 'soma' comes from the Greek <nowiki>'</nowiki>"σῶμα"<nowiki>'</nowiki>, meaning 'body'. Although it is often used to refer to neurons, it can also refer to other cell types
Soma (biology)
5676829
in human IκBα), the IκB proteins are modified by a process called ubiquitination, which then leads them to be degraded by a cell structure called the proteasome. With the degradation of IκB, the NF-κB complex is then freed to enter the nucleus where it can 'turn on' the expression of specific genes that have DNA-binding sites for NF-κB nearby. The activation of these genes by NF-κB then leads to the given physiological response, for example, an inflammatory or immune response, a cell survival response, or cellular proliferation. Translocation of NF-κB to nucleus can be detected immunocytochemically and measured by laser
NF-κB
2984750
egg's nucleus. The two pronuclei migrate toward each other and then fuse to form a diploid cell. Karyogamy Karyogamy is the final step in the process of fusing together two haploid eukaryotic cells, and refers specifically to the fusion of the two nuclei. Before karyogamy, each haploid cell has one complete copy of the organism's genome. In order for karyogamy to occur, the cell membrane and cytoplasm of each cell must fuse with the other in a process known as plasmogamy. Once within the joined cell membrane, the nuclei are referred to as pronuclei. Once the cell membranes, cytoplasm, and
Karyogamy
2154190
controlled, in part, by the levels cAMP. Also, the catalytic subunit itself can be down-regulated by phosphorylation. The regulatory subunit dimer of PKA is important for localizing the kinase inside the cell. The dimerization and docking (D/D) domain of the dimer binds to the A-kinase binding (AKB) domain of A-kinase anchor protein (AKAP). The AKAPs localize PKA to various locations (e.g., plasma membrane, mitochondria, etc.) within the cell. AKAPs bind many other signaling proteins, creating a very efficient signaling hub at a certain location within the cell. For example, an AKAP located near the nucleus of a heart muscle cell
Protein kinase A
4223537
within the terminal repeat region, and then packaged into a virus particle (virion). The virus then becomes enveloped with a lipid membrane as it transits the nucleus and the cytoplasm to exit the cell. Thus, whereas KSHV genome is circular in the nucleus of latently infected cells, it is packaged into infectious viruses as a linear molecule. Once the virus newly infects a cell, the lipid membrane is shed and the virion travels to the nucleus. The viral genome is released where it recircularizes through a poorly understood process that appears to involve homologous recombination. The primary viral protein responsible
Kaposi's sarcoma-associated herpesvirus
182088
Wood and a colleague) and inserting it into a human egg from which the nucleus had been removed. The embryos were developed only to the blastocyst stage, at which point they were studied in processes that destroyed them. Members of the lab said that their next set of experiments would aim to generate embryonic stem cell lines; these are the "holy grail" that would be useful for therapeutic or reproductive cloning. In 2011, scientists at the New York Stem Cell Foundation announced that they had succeeded in generating embryonic stem cell lines, but their process involved leaving the oocyte's nucleus
Human cloning
83930
the nucleus from a skin cell of that patient is placed into an empty egg. The reprogrammed cell begins to develop into an embryo because the egg reacts with the transferred nucleus. The embryo will become genetically identical to the patient. The embryo will then form a blastocyst which has the potential to form/become any cell in the body. The reason why SCNT is used for cloning is because somatic cells can be easily acquired and cultured in the lab. This process can either add or delete specific genomes of farm animals. A key point to remember is that cloning
Cloning
6746111
the basement membrane and cell proliferation associated with further angiogenesis. The most important step in the angiogenesis process is the translocation of Ang to the cell nucleus. Once Ang has been translocated to the nucleus, it enhances rRNA transcription by binding to the CT-rich (CTCTCTCTCTCTCTCTCCCTC) angiogenin binding element (ABE) within the upstream intergenic region of rDNA, which subsequently activates other angiogenic factors that induce angiogenesis. However, angiogenin is unique among the many proteins that are involved in angiogenesis in that it is also an enzyme with an amino acid sequence 33% identical to that of bovine pancreatic ribonuclease (RNase) A.
Angiogenin
16624594
detail. Induced totipotent cells can be obtained by reprogramming somatic cells with somatic-cell nuclear transfer (SCNT). The process involves sucking out the nucleus of a somatic (body) cell and injecting it into an oocyte that has had its nucleus removed Using an approach based on the protocol outlined by Tachibana et al., hESCs can be generated by SCNT using dermal fibroblasts nuclei from both a middle-aged 35-year-old male and an elderly, 75-year-old male, suggesting that age-associated changes are not necessarily an impediment to SCNT-based nuclear reprogramming of human cells. Such reprogramming of somatic cells to a pluripotent state holds huge
Induced stem cells
13786291
context of other histopathological findings the label "ballooning degeneration" is not used for cell death with cytoplasmic clearing and cell swelling. Ballooned cells are typically two to three times the size of adjacent hepatocytes and are characterized by a wispy cleared cytoplasm on H&E stained sections. They can be differentiated from adipocyte-like cells by their cytoplasm and nucleus; ballooned cells have their nucleus in the centre (unlike adipocyte-like cells, which have it peripherally). Also, ballooned cells have (small) pyknotic nuclei "or" nuclei that are undergoing karyorrhexis, i.e. in the process of disintegrating. The cytoplasm of cells undergoing ballooning degeneration is
Ballooning degeneration
9666962
neutral co-lipid (helper lipid). The DNA-containing liposomes (positively charged on their surface) can fuse with the negatively charged plasma membrane of living cells, due to the neutral co-lipid mediating fusion of the liposome with the cell membrane, allowing nucleic acid cargo molecules to cross into the cytoplasm for replication or expression. In order for a cell to express a transgene, the nucleic acid must reach the nucleus of the cell to begin transcription. However, the transfected genetic material may never reach the nucleus in the first place, instead being disrupted somewhere along the delivery process. In dividing cells, the material
Lipofectamine
17991263
byproduct of normal female meiosis fuses with the egg cell to form a diploid nucleus, much as a haploid sperm cell fuses its nucleus with that of an egg cell to form a diploid genome during sexual reproduction. This method of parthenogenesis produces offspring that are homozygous at nearly all genetic loci, and inherit approximately half of their mother's genetic diversity. This form of parthenogenesis can produce male as well as WW-genotype females. Because the meiosis process proceeds normally in species employing this mechanism, they are capable of both sexual and asexual reproduction, as in the Komodo dragon and several
Parthenogenesis in squamata
97536
RNA strands are created using DNA strands as a template in a process called transcription. Under the genetic code, these RNA strands specify the sequence of amino acids within proteins in a process called translation. Within eukaryotic cells, DNA is organized into long structures called chromosomes. Before typical cell division, these chromosomes are duplicated in the process of DNA replication, providing a complete set of chromosomes for each daughter cell. Eukaryotic organisms (animals, plants, fungi and protists) store most of their DNA inside the cell nucleus and some in organelles, such as mitochondria or chloroplasts. In contrast, prokaryotes (bacteria and
DNA
3904824
the other words AICD is the negative regulator of activated T-lymphocytes. Ischemic cell death, or oncosis, is a form of accidental, or passive cell death that is often considered a lethal injury. The process is characterized by mitochondrial swelling, cytoplasm vacuolization, and swelling of the nucleus and cytoplasm. Immunogenic cell death or immunogenic apoptosis is a form of cell death caused by some cytostatic agents such as anthracyclines, oxaliplatin and bortezomib, or radiotherapy and photodynamic therapy (PDT). Pyroptosis is a highly inflammatory form of programmed cell death that occurs most frequently upon infection with intracellular pathogens and is likely to
Cell death
2963514
the RNaseIII domains and thus control the specificity of the sRNA products. The helicase domain has been implicated in processing long substrates. RNA interference is a process where the breakdown of RNA molecules into miRNA inhibits gene expression of specific host mRNA sequences. miRNA is produced within the cell starting from primary miRNA (pri-miRNA) in the nucleus. These long sequences are cleaved into smaller precursor miRNA (pre-miRNA), which are usually 70 nucleotides with a hairpin structure. Pri-miRNA are identified by DGCR8 and cleaved by Drosha to form the pre-miRNA, a process that occurs in the nucleus. These pre-miRNA are then
Dicer
17621890
from VP1. All of the capsid proteins are expressed from the late region of the viral genome, so named because expression occurs only late in the infection process. VP1 has a nuclear localization sequence that enables import from the cytoplasm where it is synthesized by the host translation machinery to the cell nucleus where new virions are assembled. This nuclear import process, mediated by karyopherins, acts on assembled VP1 pentamers in complex with VP2 or VP3; oligomerization to form capsids occurs in the nucleus. Major capsid protein VP1 Major capsid protein VP1 is a viral protein that is the main
Major capsid protein VP1
12757742
polysaccharide synthetase zymogen. The process of bud emergence is regulated by the synthesis of these cellular components as well as by the turgor pressure in the parent cell. Mitosis occurs, as the bud grows, and both the developing conidium and the parent cell will contain a single nucleus. A ring of chitin forms between the developing blastoconidium and its parent yeast cell. This ring grows in to form a septum. Separation of the two cells leaves a bud scar on the parent cell wall. The bud scar contains much more chitin than does the rest of the parent cell wall.
Blastoconidium
539508
is characterised by: Metabolism ceases, and the cells are almost completely filled by keratin. During the process of epithelial differentiation, cells become cornified as keratin protein is incorporated into longer keratin intermediate filaments. Eventually the nucleus and cytoplasmic organelles disappear, metabolism ceases and cells undergo a programmed death as they become fully keratinized. In many other cell types, such as cells of the dermis, keratin filaments and other intermediate filaments function as part of the cytoskeleton to mechanically stabilize the cell against physical stress. It does this through connections to desmosomes, cell-cell junctional plaques, and hemidesmosomes, cell-basement membrane adhesive structures.
Keratin
12380220
identical to chromatolysis. Central chromatolysis is the most common form of chromatolysis and is characterized by the loss or dispersion of the Nissl bodies starting near the nucleus at the center of the neuron, and then extending peripherally towards the plasma membrane. Also characteristic of central chromatolysis is the displacement of the nucleus towards the periphery of the perikaryon. Other cellular changes are observed during the process of the central chromatolysis. The process of Nissl dissolution is less apparent toward periphery of the cell body of the neuron, where normal-looking Nissl bodies may be present. Hyperplasia of neurofilaments is frequently
Chromatolysis
91146
cells. In cells with a nucleus, as in eukaryotes, the cell cycle is also divided into three periods: interphase, the mitotic (M) phase, and cytokinesis. During interphase, the cell grows, accumulating nutrients needed for mitosis, preparing it for cell division and duplicating its DNA. During the mitotic phase, the chromosomes separate. During the final stage, cytokinesis, the chromosomes and cytoplasm separate into two new daughter cells. To ensure the proper division of the cell, there are control mechanisms known as cell cycle checkpoints. The cell-division cycle is a vital process by which a single-celled fertilized egg develops into a mature
Cell cycle
15461089
a particular phenotype can be cloned within a given species, when movement is accompanied by the presence of a mutant phenotype. Transposon tagging In genetic engineering, transposon tagging is a process where transposons (transposable elements) are amplified inside a biological cell by a tagging technique. Transposon tagging has been used with several species to isolate genes. Even without knowing the nature of the specific genes, the process can still be used. By molecular separation of transposons, from a cell nucleus, the cloning is enabled for genes which contain the transposons. By using transposon tagging, researchers have been able to add
Transposon tagging
77540
best-known of these is the nucleolus, which is mainly involved in the assembly of ribosomes. After being produced in the nucleolus, ribosomes are exported to the cytoplasm where they translate mRNA. The nucleus was the first organelle to be discovered. What is most likely the oldest preserved drawing dates back to the early microscopist Antonie van Leeuwenhoek (1632–1723). He observed a "lumen", the nucleus, in the red blood cells of salmon. Unlike mammalian red blood cells, those of other vertebrates still contain nuclei. The nucleus was also described by Franz Bauer in 1804 and in more detail in 1831 by
Cell nucleus
6436937
about 200 nucleotides. One of the necessary protein complexes in this process is CPSF. CPSF binds to the 3' tail (AAUAAA) sequence and together with another protein called poly(A)-binding protein, recruits and stimulates the activity of poly(A) polymerase. Poly(A) polymerase is inactive on its own and requires the binding of these other proteins to function properly. After processing is complete, mRNA needs to be transported from the cell nucleus to cytoplasm. This is a three-step process involving the generation of a cargo-carrier complex in the nucleus followed by translocation of the complex through the nuclear pore complex and finally release
RNA-binding protein
6557190
out in separate compartments of the cell (the nucleus and cytoplasm). Eukaryotic mRNA precursors must be processed in the nucleus (e.g., capping, polyadenylation, splicing) before they are exported to the cytoplasm for translation. Translation can also be affected by ribosomal pausing, which can trigger endonucleolytic attack of the mRNA, a process termed mRNA no-go decay. Ribosomal pausing also aids co-translational folding of the nascent polypeptide on the ribosome, and delays protein translation while it is encoding mRNA. This can trigger ribosomal frameshifting. Termination of elongation depends on eukaryotic release factors. The process is similar to that of prokaryotic termination, but
Eukaryotic translation
9850032
Bacterial transcription Bacterial transcription is the process in which messenger RNA transcripts of genetic material in bacteria are produced, to be translated for the production of proteins. Unlike in eukaryotes, bacterial transcription and translation can occur simultaneously in the cytoplasm. This is impossible in eukaryotes, where transcription occurs in a membrane-bound nucleus while translation occurs outside the nucleus in the cytoplasm (see also Eukaryotic transcription). In bacteria genetic material is not enclosed in a membrane-enclosed nucleus and has access to ribosomes in the cytoplasm. Transcription is carried out by RNA polymerase but its specificity is controlled by sequence-specific DNA binding
Bacterial transcription
77548
ring-shaped structure at a position where the inner and outer membranes fuse. Attached to the ring is a structure called the "nuclear basket" that extends into the nucleoplasm, and a series of filamentous extensions that reach into the cytoplasm. Both structures serve to mediate binding to nuclear transport proteins. Most proteins, ribosomal subunits, and some DNAs are transported through the pore complexes in a process mediated by a family of transport factors known as karyopherins. Those karyopherins that mediate movement into the nucleus are also called importins, whereas those that mediate movement out of the nucleus are called exportins. Most
Cell nucleus
15461088
Transposon tagging In genetic engineering, transposon tagging is a process where transposons (transposable elements) are amplified inside a biological cell by a tagging technique. Transposon tagging has been used with several species to isolate genes. Even without knowing the nature of the specific genes, the process can still be used. By molecular separation of transposons, from a cell nucleus, the cloning is enabled for genes which contain the transposons. By using transposon tagging, researchers have been able to add genetic elements from maize (corn) and Antirrhinum into some other species (such as tobacco, aspen and others). A gene responsible for
Transposon tagging
18810742
off" of petals from flowers or leaves from trees, is a highly regulated, evolutionarily conserved, and energy-requiring process by which activation of specific signaling cascades ultimately leads to cell death. An apoptotic cell undergoes structural changes including cell shrinkage, plasma membrane blebbing, nuclear condensation, and fragmentation of the DNA and nucleus. This is followed by fragmentation into apoptotic bodies that are quickly removed by phagocytes, thereby preventing an inflammatory response. It is a mode of cell death defined by characteristic morphological, biochemical and molecular changes. It was first described as a "shrinkage necrosis", and then this term was replaced by
FAM162A
6791355
binding cell surface receptors that span the cell's plasma membrane. Once activated, receptors stimulate signal transduction events in the cytoplasm, a process by which proteins and second messengers relay signals from outside the cell to the cell nucleus and instructs the cell to grow or divide. The HRAS protein is a GTPase and is an early player in many signal transduction pathways and is usually associated with cell membranes due to the presence of an isoprenyl group on its C-terminus. HRAS acts as a molecular on/off switch, once it is turned on it recruits and activates proteins necessary for the
HRAS
576728
fusion of gametes, as in animals and plants. There are three types of fertilisation processes in protozoa: Fertilisation in algae occurs by binary fission. The pseudopodia is first withdrawn and the nucleus starts dividing. When the cytoplasm is divided, the cytoplasm is also divided into two equal parts for each daughter cell. Two daughter cells are produced by one parent cell. It involves the process of mitosis. Fertilisation in fungi. In many fungi (except chytrids), as in some protists, fertilisation is a two step process. ... In chytrid fungi, fertilisation occurs in a single step with the fusion of gametes,
Fertilisation
4210104
Retrograde signaling Retrograde signaling in biology is a process whereby the function of one part of a cell is controlled by feedback from another part of the cell, or where one cell sends reciprocal messages back to another cell that regulates it. In cell biology, retrograde signaling occurs between different subcellular organelles. A typical example in plants is retrograde signaling from the plastid to control nuclear gene expression. In neuroscience, retrograde signaling (or retrograde neurotransmission) refers more specifically to the process by which a retrograde messenger, such as anandamide or nitric oxide, is released by a postsynaptic dendrite or cell
Retrograde signaling
15228437
are heritable between sexual conjugations. "C. uncinata" goes through asexual reproduction for cell division and duplication called amitosis. As "C. uncinata" has two nuclei, it goes through two different styles of division of the nuclei. The germ-line nucleus goes through mitosis during asexual division while the somatic nucleus undergoes amitosis. Amitosis is a stochastic process where unlike in mitosis, there is no spindle formation to segregate chromosomes during nuclear division. Instead, the chromosomes within the somatic nucleus are duplicated, and the nucleus goes through binary division. The precise mechanism is unknown, but it is believed that somatic chromosomes that are
Chilodonella uncinata
2800823
grows in size and replicates its DNA without cytokinesis in a process called endomitosis. As a result, the nucleus of the megakaryocyte can become very large and lobulated, which, under a light microscope, can give the false impression that there are several nuclei. In some cases, the nucleus may contain up to 64N DNA, or 32 copies of the normal complement of DNA in a human cell. The cytoplasm, just as the platelets that bud off from it, contains α-granula and dense bodies. Megakaryocytes are derived from hematopoietic stem cell precursor cells in the bone marrow. They are produced primarily
Megakaryocyte
1879092
that they contain all of the machinery necessary to translate proteins but lack a nucleus. Since a cell's nucleus contains many components that make studying translation difficult, these cells are quite useful. Scientists can collect reticulocytes from animals such as rabbits and extract the mRNA and translation enzymes to study protein translation in a cell-free, in vitro system, allowing greater control over the environment in which proteins are being synthesized. Reticulocyte Reticulocytes are immature red blood cells, typically composing about 1% of the red blood cells in the human body. In the process of erythropoiesis (red blood cell formation), reticulocytes
Reticulocyte
2619744
viral lifecycle is very rapid with the whole process of replication being completed on average within 8 hours. However, as little as 30 minutes after initial infection, cell protein synthesis declines to almost zero output – essentially the macromolecular synthesis of cell proteins is shut off. Over the next 1–2 hours there is a loss of margination of chromatin and homogeneity in the nucleus, before the viral proteins start to be synthesized and a vacuole appears in the cytoplasm close to the nucleus that gradually starts to spread as the time after infection reaches around 3 hours. After this time
Picornavirus
83931
is achieved when the oocyte maintains its normal functions and instead of using sperm and egg genomes to replicate, the oocyte is inserted into the donor's somatic cell nucleus. The oocyte will react on the somatic cell nucleus, the same way it would on sperm cells. The process of cloning a particular farm animal using SCNT is relatively the same for all animals. The first step is to collect the somatic cells from the animal that will be cloned. The somatic cells could be used immediately or stored in the laboratory for later use. The hardest part of SCNT is
Cloning
77594
that the nucleus instead originated from a single ancestral cell that evolved a second exterior cell membrane; the interior membrane enclosing the original cell then became the nuclear membrane and evolved increasingly elaborate pore structures for passage of internally synthesized cellular components such as ribosomal subunits. Cell nucleus In cell biology, the nucleus (pl. nuclei; from Latin or , meaning "kernel" or "seed") is a membrane-enclosed organelle found in eukaryotic cells. Eukaryotes usually have a single nucleus, but a few cell types, such as mammalian red blood cells, have no nuclei, and a few others including osteoclasts have many. Cell
Cell nucleus
348409
destinations, through the secretory pathway. Bound ribosomes usually produce proteins that are used within the plasma membrane or are expelled from the cell via "exocytosis". In bacterial cells, ribosomes are synthesized in the cytoplasm through the transcription of multiple ribosome gene operons. In eukaryotes, the process takes place both in the cell cytoplasm and in the nucleolus, which is a region within the cell nucleus. The assembly process involves the coordinated function of over 200 proteins in the synthesis and processing of the four rRNAs, as well as assembly of those rRNAs with the ribosomal proteins. The ribosome may have
Ribosome
4562544
independently. Flemming investigated the process of cell division and the distribution of chromosomes to the daughter nuclei, a process he called mitosis from the Greek word for thread. However, he did not see the splitting into identical halves, the daughter chromatids. He studied mitosis both "in vivo" and in stained preparations, using as the source of biological material the fins and gills of salamanders. These results were published first in 1878 and in 1882 in the seminal book "Zellsubstanz, Kern und Zelltheilung" (1882; Cell substance, nucleus and cell division). On the basis of his discoveries, Flemming surmised for the first
Walther Flemming
10565448
cells to use for the reparative fusion, determining the best way to introduce the chosen cells into the desired tissue, discovering methods to increase the incidence in cell fusion, and ensuring that the resulting fusion products will function properly. If these challenges can be overcome then cell fusion may have therapeutic potential. Cell fusion Cell fusion is an important cellular process in which several uninuclear cells (cells with a single nucleus) combine to form a multinuclear cell, known as a syncytium. Cell fusion occurs during differentiation of muscle, bone and trophoblast cells, during embryogenesis, and during morphogenesis. Cell fusion is
Cell fusion
18854499
T cell receptor revision T cell receptor revision (alternative term: antigen receptor editing) is a process in the peripheral immune system which is used by mature T cells to alter their original antigenic specificity based on rearranged T cell receptors (TCR). This process can lead either to continuous appearance of potentially self-reactive T cells in the body, not controlled by the central tolerance mechanism in the thymus or better eliminate such self-reactive T cells on the other hand and thus contributing to peripheral tolerance - the extent of each has not been completely understood yet. This process occurs during follicular
T cell receptor revision
3093508
enough time for the molecule to travel into the nucleus of the cell, subsequently reacting with macromolecules such as DNA. ROS are produced intracellularly through multiple mechanisms and depending on the cell and tissue types, the major sources being the "professional" producers of ROS: NADPH oxidase (NOX) complexes (7 distinct isoforms) in cell membranes, mitochondria, peroxisomes, and endoplasmic reticulum. Mitochondria convert energy for the cell into a usable form, adenosine triphosphate (ATP). The process in which ATP is produced, called oxidative phosphorylation, involves the transport of protons (hydrogen ions) across the inner mitochondrial membrane by means of the electron transport
Reactive oxygen species
9348901
as larger parts of the fragmented apoptotic cell nucleus. Blebbing also has important functions in other cellular processes, including cell locomotion, cell division, and physical or chemical stresses. Blebs have been seen in cultured cells in certain stages of the cell cycle. These blebs are used for cell locomotion in embryogenesis. The types of blebs vary greatly, including variations in bleb growth rates, size, contents, and actin content. It also plays an important role in all five varieties of necrosis, a generally detrimental process. However, cell organelles do not spread into necrotic blebs. In 2004, a chemical known as blebbistatin
Bleb (cell biology)
9757985
guiding the regrowing axon. At the neuronal cell body, a process called chromatolysis occurs in which the nucleus migrates to the periphery of the cell body and the endoplasmic reticulum breaks up and disperses. Nerve damage causes the metabolic function of the cell to change from that of producing molecules for synaptic transmission to that of producing molecules for growth and repair. These factors include GAP-43, tubulin and actin. Chromatolysis is reversed when the cell is prepared for axon regeneration. Axon regeneration is characterized by the formation of a growth cone. The growth cone has the ability to produce a
Nerve injury
12886824
erythematosus cell—a misnomer, as it occurs with other diseases as well). Discovered by a team of researchers at the Mayo Clinic, they discovered that the white blood cells contained the nucleus of another cell that was pushing against the white's cell proper nucleus. Noting that the invading nucleus was coated with antibody that allowed it to be ingested by a phagocytic or scavenger cell, they named the antibody that causes one cell to ingest another the LE factor and the two nuclei cell result in the LE cell. The LE cell, it was determined, was a part of an anti-nuclear
Systemic lupus erythematosus
3971327
cell lysis and formation of a viral plaque. Cell culture Cell culture is the process by which cells are grown under controlled conditions, generally outside their natural environment. After the cells of interest have been isolated from living tissue, they can subsequently be maintained under carefully controlled conditions. These conditions vary for each cell type, but generally consist of a suitable vessel with a substrate or medium that supplies the essential nutrients (amino acids, carbohydrates, vitamins, minerals), growth factors, hormones, and gases (CO, O), and regulates the physio-chemical environment (pH buffer, osmotic pressure, temperature). Most cells require a surface or
Cell culture
3381183
perception of phenolic compounds such as [[acetosyringone]] emitted by wounded plant tissue and follows cell-cell contact. Then this process succeeds the [[Macromolecule|macromolecular]] [[Translocation (genetics)|translocation]] from "Agrobacterium" to cytoplasm of host cell, transmission of T-DNA along with associated proteins (called T-complex) to the host cell nucleus followed by disassembly of the T-complex, stable integration of T-DNA into host plant [[genome]], and expression of the transferred [[gene]]s. The integration of T-DNA into a host genome involves the formation of a nick at the right border of the Ti plasmid. This nick creates a region of single stranded DNA from the left border
Transfer DNA
77583
the chromatids in the presence of the nuclear envelope. Therefore, the early stages in the cell cycle, beginning in prophase and until around prometaphase, the nuclear membrane is dismantled. Likewise, during the same period, the nuclear lamina is also disassembled, a process regulated by phosphorylation of the lamins by protein kinases such as the CDC2 protein kinase. Towards the end of the cell cycle, the nuclear membrane is reformed, and around the same time, the nuclear lamina are reassembled by dephosphorylating the lamins. However, in dinoflagellates, the nuclear envelope remains intact, the centrosomes are located in the cytoplasm, and the
Cell nucleus
14079711
the latter is sometimes referred to as schizogony, despite its general meaning. Merogony is an asexually reproductive process of apicomplexa. After infecting a host cell, a trophozoite (see glossary below) increases in size while repeatedly replicating its nucleus and other organelles. During this process, the organism is known as a ' or '. Cytokinesis next subdivides the multinucleated schizont into numerous identical daughter cells called merozoites (see glossary below), which are released into the blood when the host cell ruptures. Organisms whose life cycles rely on this process include "Theileria", "Babesia", "Plasmodium", and "Toxoplasma gondii." Sporogony is a type of
Apicomplexan life cycle
7311292
The study demonstrated that GAPDH is S-nitrosylated by NO in response to cell stress, which causes it to bind to the protein SIAH1, a ubiquitin ligase. The complex moves into the nucleus where Siah1 targets nuclear proteins for degradation, thus initiating controlled cell shutdown. In subsequent study the group demonstrated that deprenyl, which has been used clinically to treat Parkinson's disease, strongly reduces the apoptotic action of GAPDH by preventing its S-nitrosylation and might thus be used as a drug. GAPDH acts as a reversible metabolic switch under oxidative stress. When cells are exposed to oxidants, they need excessive amounts
Glyceraldehyde 3-phosphate dehydrogenase