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921.
The major cell wall-associated protein of the equine pathogen Streptococcus equi subsp. equi is a fibrinogen-binding protein (FgBP) which binds horse fibrinogen and equine IgG-Fc avidly through residues located in the N-terminal half and central regions of the molecule, respectively. The molecule is a major virulence factor for the organism and displays protective potential. In the present study, we use circular dichroism spectroscopy to investigate the secondary structure of the protein and show through the analysis of a panel of recombinant FgBP truncates that the C-terminal portion of FgBP contains an extensive alpha-helical coiled-coil structure that contributes to the thermal stability of the molecule. 相似文献
922.
Yu. V. Petrov M. I. Patrov V. K. Gusev A. E. Ivanov V. B. Minaev N. V. Sakharov S. Yu. Tolstyakov G. S. Kurskiev 《Plasma Physics Reports》2011,37(12):1001-1005
In the experiments carried out on the Globus-M tokamak in regimes with injection of 26-keV neutral beams with a power of 0.75–0.85
MW, two branches of instabilities excited by fast ions were observed in the early stage of a discharge: a low-frequency energetic
particle mode (EPM) in the frequency range of 5–30 kHz and a high-frequency mode in the range of 50–200 kHz, identified as
a toroidal Alfvén eigenmode (TAE). The TAE developed in the initial phase of the discharge at q(0) > 1 and terminated when sawtooth oscillations were excited at q(0) < 1. The spectrum and spatial localization of the mode agree with predictions of the linear theory. The modes observed
in the Globus-M tokamak possess both properties common to other tokamaks and their own specific features. 相似文献
923.
924.
Gray BN Bougri O Carlson AR Meissner J Pan S Parker MH Zhang D Samoylov V Ekborg NA Michael Raab R 《Plant biotechnology journal》2011,9(9):1100-1108
In planta expression of cell wall degrading enzymes is a promising approach for developing optimized biomass feedstocks that enable low-cost cellulosic biofuels production. Transgenic plants could serve as either an enzyme source for the hydrolysis of pretreated biomass or as the primary biomass feedstock in an autohydrolysis process. In this study, two xylanase genes, Bacillus sp. NG-27 bsx and Clostridium stercorarium xynB, were expressed in maize (Zea mays) under the control of two different promoters. Severe phenotypic effects were associated with xylanase accumulation in maize, including stunted plants and sterile grains. Global expression of these xylanases from the rice ubiquitin 3 promoter (rubi3) resulted in enzyme accumulation of approximately 0.01 mg enzyme per gram dry weight, or approximately 0.1% of total soluble protein (TSP). Grain-specific expression of these enzymes from the rice glutelin 4 promoter (GluB-4) resulted in higher-level accumulation of active enzyme, with BSX and XynB accumulating up to 4.0% TSP and 16.4% TSP, respectively, in shriveled grains from selected T0 plants. These results demonstrate the potential utility of the GluB-4 promoter for biotechnological applications. The phenotypic effects of xylanase expression in maize presented here demonstrate the difficulties of hemicellulase expression in an important crop for cellulosic biofuels production. Potential alternate approaches to achieve xylanase accumulation in planta without the accompanying negative phenotypes are discussed. 相似文献
925.
Tserendorj A Anceno AJ Houpt ER Icenhour CR Sethabutr O Mason CS Shipin OV 《EcoHealth》2011,8(3):349-364
Assessment of microbial hazards associated with certain environmental matrices, livelihood strategies, and food handling practices
are constrained by time-consuming conventional microbiological techniques that lead to health risk assessments of narrow geographic
or time scope, often targeting very few pathogens. Health risk assessment based on one or few indicator organisms underestimates
true disease burden due a number of coexisting causative pathogens. Here, we employed molecular techniques in a survey of
Cryptosporidium parvum, Giardia lamblia, Campylobacter jejuni, Escherichia coli O157:H7, Listeria monocytogenes, Salmonella spp., Shigella spp., Vibrio cholera, and Rotavirus A densities in canal water with respect to seasonality and spatial distribution of point–nonpoint pollution
sources. Three irrigational canals stretching across nearly a 150-km2 periurban landscape, traditionally used for agricultural irrigation but function as vital part of municipal wastewater stabilization
in recent years, were investigated. Compiled stochastic data (pathogen concentration, susceptible populations) and literature-obtained
deterministic data (pathogen dose–response model parameter values) were used in estimating waterborne gastroenteritis burden.
Exposure scenarios include swimming or fishing, consuming canal water-irrigated vegetables, and ingesting or inhaling water
aerosols while working in canal water-irrigated fields. Estimated annual gastroenteritis burden due individual pathogens among
the sampling points was −10.6log10 to −2.2log10 DALYs. Aggregated annual gastroenteritis burden due all the target pathogens per sampling point was −3.1log10 to −1.9log10 DALYs, far exceeding WHO acceptable limit of −6.0log10 DALYs. The present approach will facilitate the comprehensive collection of surface water microbiological baseline data and
setting of benchmarks for interventions aimed at reducing microbial hazards in similar landscapes worldwide. 相似文献
926.
In the present paper we demonstrate the use of inverse Broyden’s algorithm (IBA) in the simulation of fracture in single iron
crystals. The iron crystal structure is treated as a truss system, while the forces between the atoms situated at the nodes
are defined by modified Morse inter-atomic potentials. The evolution of lattice structure is interpreted as a sequence of
equilibrium states corresponding to the history of applied load/deformation, where each equilibrium state is found using an
iterative procedure based on IBA. The results presented demonstrate the success of applying the IBA technique for modeling
the mechanisms of elastic, plastic and fracture behavior of single iron crystals. 相似文献
927.
Jin G Reitman ZJ Spasojevic I Batinic-Haberle I Yang J Schmidt-Kittler O Bigner DD Yan H 《PloS one》2011,6(2):e16812
Background
Gliomas frequently contain mutations in the cytoplasmic NADP+-dependent isocitrate dehydrogenase (IDH1) or the mitochondrial NADP+-dependent isocitrate dehydrogenase (IDH2). Several different amino acid substitutions recur at either IDH1 R132 or IDH2 R172 in glioma patients. Genetic evidence indicates that these mutations share a common gain of function, but it is unclear whether the shared function is dominant negative activity, neomorphic production of (R)-2-hydroxyglutarate (2HG), or both.Methodology/Principal Findings
We show by coprecipitation that five cancer-derived IDH1 R132 mutants bind IDH1-WT but that three cancer-derived IDH2 R172 mutants exert minimal binding to IDH2-WT. None of the mutants dominant-negatively lower isocitrate dehydrogenase activity at physiological (40 µM) isocitrate concentrations in mammalian cell lysates. In contrast to this, all of these mutants confer 10- to 100-fold higher 2HG production to cells, and glioma tissues containing IDH1 R132 or IDH2 R172 mutations contain high levels of 2HG compared to glioma tissues without IDH mutations (54.4 vs. 0.1 mg 2HG/g protein).Conclusions
Binding to, or dominant inhibition of, WT IDH1 or IDH2 is not a shared feature of the IDH1 and IDH2 mutations, and thus is not likely to be important in cancer. The fact that the gain of the enzymatic activity to produce 2HG is a shared feature of the IDH1 and IDH2 mutations suggests that this is an important function for these mutants in driving cancer pathogenesis. 相似文献928.
Dongcheng Zhang Amy L. VanFossen Ryan M. Pagano Jeremy S. Johnson Matthew H. Parker Shihao Pan Benjamin N. Gray Elaina Hancock Daniel J. Hagen H��ctor A. Lucero Binzhang Shen Philip A. Lessard Cairn Ely Meghan Moriarty Nathan A. Ekborg Oleg Bougri Vladimir Samoylov Gabor Lazar R. Michael Raab 《Bioenergy Research》2011,4(4):276-286
Significant amounts of cell wall degrading (CWD) enzymes are required to degrade lignocellulosic biomass into its component sugars. One strategy for reducing exogenous enzyme production requirements is to produce the CWD enzymes in planta. For this work, various CWD enzymes were expressed in maize (Zea mays). Following growth and dry down of the plants, harvested maize stover was tested to determine the impact of the expressed enzymes on the production of glucose and xylose using different exogenous enzyme loadings. In this study, a consolidated pretreatment and hydrolysis process consisting of a moderate chemical pretreatment at temperatures below 75°C followed by enzymatic hydrolysis using an in-house enzyme cocktail was used to evaluate engineered transgenic feedstocks. The carbohydrate compositional analysis showed no significant difference in the amounts of glucan and xylan between the transgenic maize plants expressing CWD enzyme(s) and the control plants. Hydrolysis results demonstrated that transgenic plants expressing CWD enzymes achieved up to 141% higher glucose yield and 172% higher xylose yield over the control plants from enzymatic hydrolysis under the experimental conditions. The hydrolytic performance of a specific xylanase (XynA) expressing transgenic event (XynA.2015.05) was heritable in the next generation, and the improved properties can be achieved even with a 25% reduction in exogenous enzyme loading. Simultaneous saccharification and fermentation of biomass hydrolysates from two different transgenic maize lines with yeast (Saccharomyces cerevisiae D5A) converted 65% of the biomass glucan into ethanol, versus only a 42% ethanol yield with hydrolysates from control plants, corresponding to a 55% improvement in ethanol production. 相似文献
929.
Metabolic profiling is considered to be a very promising tool for diagnostic purposes, for assessing nutritional status and response to drugs. However, it is also evident that human metabolic profiles have a complex nature, influenced by many external factors. This, together with the understanding of the difficulty to assign people to distinct groups and a general move in clinical science towards personalized medicine, raises the interest to explore individual and variable metabolic features for each individual separately in longitudinal study design. In the current paper we have analyzed a set of metabolic profiles of a selection of six urine samples per person from a set of healthy individuals by (1)H NMR and reversed-phase UPLC-MS. We have demonstrated that the method for recovery of individual metabolic phenotypes can give complementary information to another established method for analysis of longitudinal data--multilevel component analysis. We also show that individual metabolic signatures can be found not only in (1)H NMR data, as has been demonstrated before, but also even more strongly in LC-MS data. 相似文献
930.
Ramautar R Nevedomskaya E Mayboroda OA Deelder AM Wilson ID Gika HG Theodoridis GA Somsen GW de Jong GJ 《Molecular bioSystems》2011,7(1):194-199
The potential of capillary electrophoresis time-of-flight mass spectrometry (CE-TOF-MS) using capillaries coated with a triple layer of polybrene-dextran sulfate-polybrene (PB-DS-PB) was evaluated for metabolic profiling of human urine. The method covers various metabolite classes and stable metabolic profiles of urine samples were obtained with favourable migration time repeatability (RSDs <1%). The PB-DS-PB CE-TOF-MS method was used for the analysis of human urine samples from 30 males and 30 females, which had been previously analyzed by reversed-phase UPLC-TOF-MS. Multivariate data analysis of the obtained data provided clear distinction between urine samples from males and females, emphasizing gender differences in metabolic signatures. Nearly all compounds responsible for male-female classification in CE-TOF-MS were different from the classifying compounds in UPLC-TOF-MS. Almost all compounds causing classification in the CE-TOF-MS study were highly polar and did not exhibit retention in the reversed-phase UPLC system. In addition, the CE-TOF-MS classifiers had an m/z value in the range of 50-150, whereas 95% of the classifying features found with UPLC-TOF-MS had an m/z value above 150. The CE-TOF-MS method therefore appears to be highly complementary to the UPLC-TOF-MS method providing classification based on different classes of metabolites. 相似文献