Cell surface engineering with functional polymers is an effective strategy to modulate cell activity. In this work, we develop a new bio-palladium catalyzed polymerization strategy for in-situ synthesis of conjugated polymers on living cell surfaces. Through Sonagashira polymerization reaction, photoactive polyphenyleneethynylene (PPE) is synthesized on the cell surface via cell-generated bio-Pd catalyst. The in-situ formed PPE is identified by excellent light-harvest capacity and blue fluorescence on the surfaces of E. coli and C. pyrenoidosa. Besides imaging microbes for tracing the polymerization process, PPE also exhibits enhanced antibacterial activity against E. coli. Moreover, it can augment the ATP synthesis of C. pyrenoidosa through enlarging the light absorption and accelerating the cyclic electron transport of the algae. By using this bio-metal catalyzed polymerization method, functional polymers can be in-situ synthesized on the living cell surface, which paves a new way for modulating cell functions.


The longitudinal instability of an intense coasting beam in the ESR (Experimentier–Speicherring) [G. Rumolo et al., Nucl. Instrum. Methods A415, 411 (1998)] has been investigated far away from the stability boundary for several values of the machine impedance. Experiments have clearly shown the growth of the slow wave, generation of higher harmonics, asymmetric wave steepening, and saturation. A one-dimensional fluid model has been successfully employed to explain the growth of the slow wave as well as the nonlinear steepening and the harmonic generation. Taking into account the effects of the initial momentum spread of the beam through a modified space charge impedance, the model predicts with high accuracy the rise time and the frequency shift of the unstable wave. Subsequently, nonlinear convective effects are shown to give rise to wave steepening and harmonic generation. Predictions of the fluid model are compared to experimental data and with those obtained under a full kinetic model as well as from ...


The degradation of transitory starch in the chloroplast to provide fuel for the plant during the night requires a suite of enzymes that generate a series of short chain linear glucans. However, glucans of less than four glucose units are no longer substrates for these enzymes, whilst export from the plastid is only possible in the form of either maltose or glucose. In order to make use of maltotriose, which would otherwise accumulate, disproportionating enzyme 1 (DPE1; a 4-α-glucanotransferase) converts two molecules of maltotriose to a molecule of maltopentaose, which can now be acted on by the degradative enzymes, and one molecule of glucose that can be exported. We have determined the structure of the Arabidopsis plastidial DPE1 (AtDPE1) and, through ligand soaking experiments, we have trapped the enzyme in a variety of conformational states. AtDPE1 forms a homodimer with a deep, long and openended active site canyon contained within each subunit. The canyon is divided into donor and acceptor sites with the catalytic http://www.jbc.org/cgi/doi/10.1074/jbc.M115.682245 The latest version is at JBC Papers in Press. Published on October 26, 2015 as Manuscript M115.682245 Copyright 2015 by The American Society for Biochemistry and Molecular Biology, Inc. by gest on O cber 8, 2015 hp://w w w .jb.org/ D ow nladed from Crystal structure of plant disproportionating enzyme DPE1 2 residues at their junction; a number of loops around the active site adopt different conformations dependent on the occupancy of these sites. The "gate" is the most dynamic loop, and appears to play a role in substrate capture, in particular, in the binding of the acceptor molecule. Subtle changes in the configuration of the active site residues may prevent undesirable reactions or abortive hydrolysis of the covalently bound enzyme-substrate intermediate. Together, these observations allow us to delineate the complete AtDPE1 disproportionation cycle in structural terms. INTRODUCTION A proportion of the photosynthate generated by plants during the daytime is stored as starch in the chloroplast. At night, this transitory starch is broken down by a suite of degradative enzymes to provide energy for the plant (1-3). Degradation involves the hydrolysis of the α-1,4 and α-1,6 linkages of the starch polymers, principally by β-amylases and debranching enzymes, respectively, releasing short malto-oligosaccharides and glucose, respectively (4-6), although none of these hydrolytic enzymes can act on substrates shorter than four glucose units i.e. maltose and maltotriose (1,7). Since only glucose and maltose are exportable to the cytosol, further enzymatic activity is required to prevent the build-up of maltotriose in the chloroplast. This role is fulfilled by disproportionating enzyme 1 (DPE1), which is the plant plastidial isoform of 4-α-glucanotransferase (EC 22.214.171.124) that is found in all kingdoms of life, although it is referred to as amylomaltase in bacteria. In Arabidopsis, the essential role of DPE1 (AtDPE1) was revealed by characterisation of a mutant lacking this enzyme: maltotriose accumulated in leaves at night, and the rate of night-time starch degradation was reduced (8). Data from a number of plants show that DPE1 enzymes preferentially use maltotriose as a substrate, transferring a maltosyl unit from one molecule to another to generate glucose, which is exportable, and maltopentaose, which can be attacked further by β-amylase or starch phosphorylase (9-13). Additional maltosyl transfer by DPE1 to the newly formed maltopentaose is possible, although more rounds of elongation are less likely in vivo because the longer chain glucans become inhibitory to DPE1 activity (10), and these would be efficiently degraded by the aforementioned hydrolytic enzymes. DPE1 can be used in vitro to produce large ring cycloamyloses with degrees of polymerisation (DP) in the range 16 – 50 (11,14), although there is no evidence for this occurring in vivo. Cycloamyloses have a number of biotechnological applications including drug (15) or gene (16) delivery, and in the removal of detergents following protein refolding experiments (17). Plant disproportionating enzymes have also been used to transfer glucans from cheap donor molecules onto acceptor molecules, for example, to generate fluorinated oligosaccharides (18) and to generate novel acarviostatin-like molecules (19). Amylomaltase can also be used to modify starches in order to make thermoreversible gels (20) and alternatives to gelatine, and to replace fats in yoghurt (21). DPE1 and amylomaltase belong to the GH77 family, as defined in the CAZy database (22,23) and, together with GH13, which includes the α-amylases and the cyclodextrin glycosyltransferases, and GH70, which includes the dextransucrases, they form the GH-H clan (24). The structures of several amylomaltases from thermophilic bacteria have been elucidated (25-28), and one unliganded potato enzyme structure has been deposited in the Protein Data Bank (PDB code 1X1N), but is not described in the literature (Imamura et al., unpublished). Very recently, the structure of the mesophilic amylomaltase from E. coli (also referred to as MalQ) has also been reported (29). by gest on O cber 8, 2015 hp://w w w .jb.org/ D ow nladed from Crystal structure of plant disproportionating enzyme DPE1 3 Here we present crystal structures of Arabidopsis thaliana DPE1 (AtDPE1), revealing both covalently and non-covalently bound complexes of the enzyme with a variety of relevant ligands. As such, this represents the most extensive structural study so far reported for this class of enzyme. We define key protein-ligand interactions and describe a series of conformational changes that are linked to active site occupancy, which together direct the course of catalysis and, crucially, favour transglycosylation over hydrolysis. Moreover, these structures help to explain why maltotriose is the preferred substrate, and why longer glucans are inhibitory to catalysis. Overall, our data permit a structural definition of the complete catalytic cycle of the enzyme and allow us to propose a mechanism for the industrially important production of large cyclic products. EXPERIMENTAL PROCEDURES Crystallization and X-ray data collection AtDPE1 protein was prepared as previously described (11) to give a sample corresponding to residues 46-576 of the wild-type amino acid sequence (i.e. lacking the N-terminal transit peptide; UniProtKB/Swiss-Prot entry Q9LV91) and preceded by a hexahistidine tag [encoded by the pET151/D-TOPO vector (Invitrogen)]. The tag was not cleaved prior to crystallization by the hanging drop vapour diffusion method at 20 °C. 1 μl of a precipitant solution consisting of 9% (w/v) PEG2000 MME in 0.1 M HEPES-NaOH, pH 8.0 was added to 1 μl of protein at a concentration of ~10 mg/ml in 20 mM HEPES-NaOH, pH 7.5, 150 mM NaCl [protein concentration was estimated on a Nanovue spectrophotometer (GE Healthcare) using an extinction coefficient of 128590 M cm calculated from the amino acid composition by ProtParam (30)]. Crystals were cryoprotected using the precipitant solution supplemented with 20% (v/v) ethylene glycol in place of an equivalent volume of buffer. Ligand soaking solutions were made up in this cryoprotectant solution at 10 mM for maltotriose (MA3; Sigma-Aldrich), acarbose (ACR; Toronto Research Chemicals Inc.) and β-cyclodextrin (BCD; Wacker-Chemie GMBH), at 0.9 mM for acarviostatin II01 (ACV; production details in below), and at 1 mg/ml for cycloamylose (CAM; Wako Pure Chemical Industries Ltd). Crystals were soaked overnight in 5 μl drops of these solutions before harvesting and flash-cooling in liquid nitrogen using LithoLoops (Molecular Dimensions). The mounted crystals were stored in Unipuck cassettes (MiTeGen) prior to transport to the Diamond Light Source (Oxfordshire, UK) where they were transferred robotically to the goniostat on either beamline I04 or I04-1 and maintained at -173 °C with a Cryojet cryocooler (Oxford Instruments). Xray data were recorded using either a Quantum 315 CCD (ADSC) or a Pilatus 2M (Dectris) detector, then integrated using either MOSFLM (31) or XDS (32), and scaled and merged using SCALA (33) or AIMLESS (34); the resultant data collection statistics are summarized in Table 1. Structure solution and refinement AtDPE1 shares 75% amino acid sequence identity with the equivalent enzyme from potato, for which there is a crystal structure available (Imamura et al., unpublished) (PDB code 1X1N). This was used as a monomer template to solve the ligand-free (LF) AtDPE1 structure at 2.13 Å resolution by molecular replacement in PHASER (35). Two copies of the template were placed in the asymmetric unit, giving a homodimer equivalent to that deduced as the biological unit for the template structure. This was consistent with previous gel filtration results which showed that AtDPE1 was dimeric in solution (11). The model of the LF structure was completed through several iterations of refinement with REFMAC5 (36) and model building with COOT (37). The final LF model was used as a starting point for the modelling and refinement of the structures of the ligand-bound complexes. The quality of the structures was evaluated using MolProbity (38) by gest on O cber 8, 2015 hp://w w w .jb.org/ D ow nladed from Crystal structure of plant disproportionating enzyme DPE1 4 and the statistics of the final models are summarised in Table 2. All structural figures were prepared using CCP4mg (39). For convenience, the AtDPE1 complex structures are referred to by three-letter abbreviations of the compound used for the soaking, and when discriminating between monomers in the same structure an A or B suffix is used e.g. ACR-A and ACR-B refers to the A and B subunits in the structure determined from the acarbosesoaked crystal, respectively. Where ligand binding was comparable between the two chains for a given structure, only the A chain was described e.g. ACV-A, BCD


A new process, subsequently patented, has been developed for and used successfully at a large Superfund site for three years at flow rates up to 400 gpm.


The implementation of the competence-based education approach at university level is a vehicle for the global transformation of the current Higher Education system. Over the past few decades, psychology has increasingly focused on the identification of core competences in the education of psychologists. The U.S., Canada and Europe have adopted competence-based education approaches. More recently, in 2013 the Tuning Latin America Project introduced the challenge to reach agreement on the education of psychologists in the region. The purpose of this research is to analyse the degree of importance and perceived achievement of the specific competences set out in the Tuning Latin America Project, among a sample of 100 advanced psychology students of a private university in the City of Buenos Aires. For such purpose, the Specific Competences Survey for students of the Tuning Latin America Project was used. All the competences obtained high ratings in terms of importance, in particular those related to professional ethics. In addition, the respondents considered that most of the competences are thoroughly developed during their university training. To conclude, further studies and analyses need to be carried out in order to identify current educational needs for psychologists and thus enhance quality and adjust psychological practice to current social needs.


The term"Normalizing Flows"is related to the task of constructing invertible transport maps between probability measures by means of deep neural networks. In this paper, we consider the problem of recovering the $W_2$-optimal transport map $T$ between absolutely continuous measures $\mu,\nu\in\mathcal{P}(\mathbb{R}^n)$ as the flow of a linear-control neural ODE. We first show that, under suitable assumptions on $\mu,\nu$ and on the controlled vector fields, the optimal transport map is contained in the $C^0_c$-closure of the flows generated by the system. Assuming that discrete approximations $\mu_N,\nu_N$ of the original measures $\mu,\nu$ are available, we use a discrete optimal coupling $\gamma_N$ to define an optimal control problem. With a $\Gamma$-convergence argument, we prove that its solutions correspond to flows that approximate the optimal transport map $T$. Finally, taking advantage of the Pontryagin Maximum Principle, we propose an iterative numerical scheme for the resolution of the optimal control problem, resulting in an algorithm for the practical computation of the approximated optimal transport map.


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A procedure of yttrium and strontium separation from calcium and other cations has been developed for rapid determination of Sr-90 in soil samples. The procedure involves yttrium, strontium and other cations bound on cation exchanger AMBERLITE IR-120, separtion of yttrium and strontium from other cations, e.g, potassium, calcium, sodium, barium, on anion exchangers AMBERLITE CG-400 or DOWEX AG Ix 8 with 0.25 mol l(-1) HNO3 in alcohol mixture as eluent, separation of yttrium from strontium on cation exchanger DOWEX 50 x 8 with 3 mol l(-1) HNO3, and determination of Sr-90 on the low-level gas-flow beta -counter and by Cherenkow counting on the liquid-scintillation counter. It has been shown that this procedure might be successfully applied in rapid determination of Sr-90, in a timesaving manner and without application of strong, concentrated acids. The method is appropriate for determination of the water soluble fraction of Sr-90 in different kinds of environmental samples (milk, water, wine, vegetables, etc.) with some modification of the sample preparation procedure.


We are interested in the large-scale environmental phenomenon of West African monsoon. It is the major atmospheric phenomenon, which drives the rainfall regime in Western Africa. The causes of spatio-temporal variability in monsoon rainfall have not yet been determined in an unequivocal manner. However, there is a considerable body of evidence suggesting that spatio-temporal changes in sea surface temperatures in the Gulf of Guinea and changes in the Saharan and sub-Saharan albedo are major factors. The aim of the study is to analyse the sensitivity of the rainfall simulated by a regional atmospheric model(MAR) to the variability of these inputs parameters. Precipitation from MAR is compared with severals precipitation data sets and the MAR reasonably simulates the Westy African monsoon. This model is expensive in computing time, the sensitivity analysis cannot be realized by running the MAR, as we work on discretization grids in space and time, that is with huge dimensions. Hence an important preliminary step is the construction of a stochastic spatio-temporal metamodel approximating the MAR. The main properties required for this metamodel is the ability to be ran in a reasonable time and the consideration of the spatio-temporal dynamic of the underlying physical phenomenon. In this study we neglect the effect of albedo and focus our effort on regressing the rainfall on the sea surface temperature (SST). An important point in this study is that the numerical storage and processing of model outputs, as far as the statistical description of the data, requires considerable computation resources. A grid environment can provide the required resources. Nevertheless, one main difficulty of the grid platform is the resource provisioning. How to find the best resource at a given time and the best amount of theses resources? The answer should come from the middleware designed with an efficient scheduler. Moreover the middleware can give a transparent access to a distributed and heterogeneous platform as a Grid. We used DIET,we will see how it schedule a huge number of computation requests according to the data management.