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191.
192.
Fourier transform infrared spectroscopy was used to investigate ligand-protein interactions in the ligand-binding domain of the GluR4 glutamate receptor subunit. Glutamate binding induces more extensive secondary structural changes in the ligand-binding domain than does kainate binding. Glutamate also alters the hydrogen bonding strength of the single free cysteine side chain in the domain, while kainate does not. On the other hand, the interaction of a binding site arginine residue with kainate appears to be stronger than that with glutamate. These results identify chemical and structural differences that may explain the different functional characteristics of the two agonists acting on ionotropic glutamate receptors. In doing so, they complement and extend recent crystallographic structures of the ligand-binding domain. 相似文献
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SOS independent survival against mitomycin C induced lethality in a rifampicin-nalidixic acid-resistant mutant of Escherichia coli 总被引:1,自引:0,他引:1
A combination of specific rifampicin-resistant (rpoB87) and nalidixic acid-resistant (gyrA87) mutations results in a marked increase in the survival of Escherichia coli against mitomycin C-induced lethality in mutants defective for SOS induction and excision repair. Although the response does not seem to be obligatorily dependent upon the RecA protein, the efficiency is markedly increased in its presence, even in a conventionally inactive form. This response is not elicited against lethality due to ultraviolet radiation or N-methyl-N' -nitro-N-nitrosoguanidine exposure. The combination of rpoB87 and gyrA87 mutations also greatly alleviates post-mitomycin C degradation of DNA under SOS non-inducible conditions. It is proposed that the rpoB subunit of RNA polymerase and gyrA subunit of DNA gyrase could participate in the repair of certain types of DNA damage, such as cross-links, in a mode independent of SOS-regulated excision repair and post-replication repair. 相似文献
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196.
A highly antagonistic Pseudomonas fluorescens strain was isolated from tomato rhizosphere and characterized for its in vitro and in vivo biocontrol potential against Pythium aphanidermatum. The identified Pseudomonas fluorescens strain (PfT-8) was capable of producing high levels of chitinase, β-1,3-glucanase, cellulase, fungitoxic metabolites and
siderophores. Seven different carrier formulations including a talc-based powder, lignite-based powder, peat-based powder,
lignite + fly ash-based powder, wettable powder, bentonite-paste and polyethylene glycol (PEG) paste were prepared utilizing
PfT-8. Shelf life was evaluated for up to 6 months of storage at ambient room temperature (28 °C). Biocontrol efficacy of
formulations was studied under greenhouse and field conditions. The formulations were stable up to at least 2 months of storage
at ambient room temperature. Among the formulations, peat, lignite, lignite+fly-ash and bentonite paste based formulations
maintained higher propagule number than others and also showed greater biocontrol potential. However, propagule number gradually
decreased with time. Several organic amendments including farm yard manure (FYM), leaf-compost, poultry manure, press mud,
vermi-compost and neem cake were incorporated into soil to study their influence on P. fluorescens colonization in the rhizosphere and on potential disease control. Soil incorporation of organic amendments and specifically
poultry manure and FYM, significantly reduced damping-off incidence and also augmented the rhizosphere population of the marked␣P.␣fluorescens strain that was resistant to streptomycin and rifampicin. An integrated␣approach of damping-off management employing dual
inoculation of PfT-8 in seed and soil coupled with soil application of organic amendments including poultry manure or␣FYM
was evaluated under field conditions. Under these conditions, damping-off incidence substantially reduced by up to 90% and
further the healthy plant stand, plant biomass and plant rhizosphere population of P. fluorescens increased significantly. 相似文献
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198.
Antonio B. Fernandez Gregory A. Panza Benjamin Cramer Saurav Chatterjee Ramya Jayaraman Wen-Chih Wu 《PloS one》2015,10(11)
Background
Age-related macular degeneration (AMD) is the leading cause of vision loss and blindness in people over 65 years old in the United States and has been associated with cardiovascular risk and decreased survival. There is conflicting data, however, regarding the contribution of AMD to the prediction of stroke.Aim
To determine whether AMD is a risk indicator for incident stroke in a meta-analysis of available prospective and retrospective cohort studies published in the English literature.Methods
We performed a systematic literature search of all studies published in English with Pub Med and other databases from 1966 to August 2014, reporting stroke incidence in patients with macular degeneration. Two investigators independently extracted the data. A random effects model was used to report Odds ratios (OR), with corresponding 95% confidence intervals (CI). Meta-regression using a mixed linear model was used to understand potential heterogeneity amongst studies.Results
We identified 9 studies that reported stroke incidence in patients with and without early AMD (N = 1,420,978). No significant association was found between early AMD with incident stroke. Combined, these 9 studies demonstrated random effects (OR, 1.12; CI, 0.86–1.47; I2 = 96%). Meta-regression on baseline covariates of age, sex, and year of publication did not significantly relate to heterogeneity.Conclusions
We found no significant relationship between AMD and incident stroke. Further studies are needed to clarify other causes of decreased survival in patients with AMD. 相似文献199.
Characterization of Microbial Dysbiosis and Metabolomic Changes in Dogs with Acute Diarrhea 总被引:1,自引:0,他引:1
Blake C. Guard James W. Barr Lavanya Reddivari Cory Klemashevich Arul Jayaraman J?rg M. Steiner Jairam Vanamala Jan S. Suchodolski 《PloS one》2015,10(5)
Limited information is available regarding the metabolic consequences of intestinal dysbiosis in dogs with acute onset of diarrhea. The aim of this study was to evaluate the fecal microbiome, fecal concentrations of short-chain fatty acids (SCFAs), as well as serum and urine metabolites in healthy dogs (n=13) and dogs with acute diarrhea (n=13). The fecal microbiome, SCFAs, and serum/urine metabolite profiles were characterized by 454-pyrosequencing of the 16S rRNA genes, GC/MS, and untargeted and targeted metabolomics approach using UPLC/MS and HPLC/MS, respectively. Significantly lower bacterial diversity was observed in dogs with acute diarrhea in regards to species richness, chao1, and Shannon index (p=0.0218, 0.0176, and 0.0033; respectively). Dogs with acute diarrhea had significantly different microbial communities compared to healthy dogs (unweighted Unifrac distances, ANOSIM p=0.0040). While Bacteroidetes, Faecalibacterium, and an unclassified genus within Ruminococcaceae were underrepresented, the genus Clostridium was overrepresented in dogs with acute diarrhea. Concentrations of fecal propionic acid were significantly decreased in acute diarrhea (p=0.0033), and were correlated to a decrease in Faecalibacterium (ρ=0.6725, p=0.0332). The predicted functional gene content of the microbiome (PICRUSt) revealed overrepresentations of genes for transposase enzymes as well as methyl accepting chemotaxis proteins in acute diarrhea. Serum concentrations of kynurenic acid and urine concentrations of 2-methyl-1H-indole and 5-Methoxy-1H-indole-3-carbaldehyde were significantly decreased in acute diarrhea (p=0.0048, 0.0185, and 0.0330, respectively). These results demonstrate that the fecal dysbiosis present in acute diarrhea is associated with altered systemic metabolic states. 相似文献