20 research outputs found

    Особенности фразеологического варианта в английском, немецком и шведском языках

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    Объект исследования – фразеология английского, немецкого и шведского языков, предмет изучения – характер вариантности ФЕ, цель исследования – выявление изоморфизма структурной организации германской фразеологии и вариантности посредством выполнения задач сопоставительного анализа, позволяющего выделить различные типы вариантов ФЕ в каждом из рассматриваемых германских языков

    C4b-binding protein inhibits particulate- and crystalline-induced NLRP3 inflammasome activation

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    Dysregulated NLRP3 inflammasome activation drives a wide variety of diseases, while endogenous inhibition of this pathway is poorly characterised. The serum protein C4b-binding protein (C4BP) is a well-established inhibitor of complement with emerging functions as an endogenously expressed inhibitor of the NLRP3 inflammasome signalling pathway. Here, we identified that C4BP purified from human plasma is an inhibitor of crystalline- (monosodium urate, MSU) and particulate-induced (silica) NLRP3 inflammasome activation. Using a C4BP mutant panel, we identified that C4BP bound these particles via specific protein domains located on the C4BP α-chain. Plasma-purified C4BP was internalised into MSU- or silica-stimulated human primary macrophages, and inhibited MSU- or silica-induced inflammasome complex assembly and IL-1β cytokine secretion. While internalised C4BP in MSU or silica-stimulated human macrophages was in close proximity to the inflammasome adaptor protein ASC, C4BP had no direct effect on ASC polymerisation in in vitro assays. C4BP was also protective against MSU- and silica-induced lysosomal membrane damage. We further provide evidence for an anti-inflammatory function for C4BP in vivo, as C4bp-/- mice showed an elevated pro-inflammatory state following intraperitoneal delivery of MSU. Therefore, internalised C4BP is an inhibitor of crystal- or particle-induced inflammasome responses in human primary macrophages, while murine C4BP protects against an enhanced inflammatory state in vivo. Our data suggests C4BP has important functions in retaining tissue homeostasis in both human and mice as an endogenous serum inhibitor of particulate-stimulated inflammasome activation

    Genome-Wide Identification of Ampicillin Resistance Determinants in Enterococcus faecium

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    Enterococcus faecium has become a nosocomial pathogen of major importance, causing infections that are difficult to treat owing to its multi-drug resistance. In particular, resistance to the β-lactam antibiotic ampicillin has become ubiquitous among clinical isolates. Mutations in the low-affinity penicillin binding protein PBP5 have previously been shown to be important for ampicillin resistance in E. faecium, but the existence of additional resistance determinants has been suggested. Here, we constructed a high-density transposon mutant library in E. faecium and developed a transposon mutant tracking approach termed Microarray-based Transposon Mapping (M-TraM), leading to the identification of a compendium of E. faecium genes that contribute to ampicillin resistance. These genes are part of the core genome of E. faecium, indicating a high potential for E. faecium to evolve towards β-lactam resistance. To validate the M-TraM results, we adapted a Cre-lox recombination system to construct targeted, markerless mutants in E. faecium. We confirmed the role of four genes in ampicillin resistance by the generation of targeted mutants and further characterized these mutants regarding their resistance to lysozyme. The results revealed that ddcP, a gene predicted to encode a low-molecular-weight penicillin binding protein with D-alanyl-D-alanine carboxypeptidase activity, was essential for high-level ampicillin resistance. Furthermore, deletion of ddcP sensitized E. faecium to lysozyme and abolished membrane-associated D,D-carboxypeptidase activity. This study has led to the development of a broadly applicable platform for functional genomic-based studies in E. faecium, and it provides a new perspective on the genetic basis of ampicillin resistance in this organism

    Human-specific inflammasome signalling pathways in macrophages

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    Salmonella-induced inflammasome activation in humans

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    Inflammasomes are macromolecular complexes that assemble upon recognition of pathogen- or danger-associated molecular patterns. Inflammasome assembly is nucleated by the oligomerisation of specific, activated pattern recognition receptors within the cytosol. Inflammasomes function as platforms for the activation of the caspase-1 protease, which in turn triggers the maturation and secretion of the pro inflammatory cytokines IL-1 beta and IL-18, and initiates pyroptosis, a highly inflammatory form of lytic cell death. Recently, additional inflammatory caspases (murine caspase-11, and human caspase-4/5) were also reported to be activated upon a pyroptosis-inducing 'non-canonical inflammasome' by direct recognition of lipopolysaccharide (LPS), a pathogen-associated molecular pattern. Here we review and discuss recent advances in our understanding of inflammasome-mediated host defence against Salmonella particularly in human cells, and their implications for cellular survival and cytokine secretion. (c) 2016 Elsevier Ltd. All rights reserved

    A LacI-family regulator activates maltodextrin metabolism of Enterococcus faecium

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    Enterococcus faecium is a gut commensal of humans and animals. In the intestinal tract, E. faecium will have access to a wide variety of carbohydrates, including maltodextrins and maltose, which are the sugars that result from the enzymatic digestion of starch by host-derived and microbial amylases. In this study, we identified the genetic determinants for maltodextrin utilization of E. faecium E1162. We generated a deletion mutant of the mdxABCD-pulA gene cluster that is homologous to maltodextrin uptake genes in other Gram-positive bacteria, and a deletion mutant of the mdxR gene, which is predicted to encode a LacI family regulator of mdxABCD-pulA. Both mutations impaired growth on maltodextrins but had no effect on the growth on maltose and glucose. Comparative transcriptome analysis showed that eight genes (including mdxABCD-pulA) were expressed at significantly lower levels in the isogenic ΔmdxR mutant strain compared to the parental strain when grown on maltose. Quantitative real-time RT-PCR confirmed the results of transcriptome analysis and showed that the transcription of a putative maltose utilization gene cluster is induced in a semi-defined medium supplemented with maltose but is not regulated by MdxR. Understanding the maltodextrin metabolism of E. faecium could yield novel insights into the underlying mechanisms that contribute to the gut commensal lifestyle of E. faecium

    Functional genomic analysis of bile salt resistance in Enterococcus faecium

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    BACKGROUND: Enterococcus faecium is a Gram-positive commensal bacterium of the mammalian intestinal tract. In the last two decades it has also emerged as a multi-resistant nosocomial pathogen. In order to survive in and colonize the human intestinal tract E. faecium must resist the deleterious actions of bile. The molecular mechanisms exploited by this bacterium to tolerate bile are as yet unexplored. RESULTS: In this study we used a high-throughput quantitative screening approach of transposon mutant library, termed Microarray-based Transposon Mapping (M-TraM), to identify the genetic determinants required for resistance to bile salts in E. faecium E1162. The gene gltK, which is predicted to encode a glutamate/aspartate transport system permease protein, was identified by M-TraM to be involved in bile resistance. The role of GltK in bile salt resistance was confirmed by the subsequent observation that the deletion of gltK significantly sensitized E. faecium E1162 to bile salts. To further characterize the response of E. faecium E1162 to bile salts, we performed a transcriptome analysis to identify genes that are regulated by exposure to 0.02% bile salts. Exposure to bile salts resulted in major transcriptional rearrangements, predominantly in genes involved in carbohydrate, nucleotide and coenzyme transport and metabolism. CONCLUSION: These findings add to a better understanding of the molecular mechanisms by which E. faecium responds and resists the antimicrobial action of bile salts

    Growth of <i>E. faecium</i> on starch, maltotetraose, maltose and glucose.

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    <p>Growth curves of <i>E. faecium</i> E1162 wild-type (black), its isogenic mutants Δ<i>mdxR</i> (red) and Δ<i>mdxABCD-pulA</i> (blue), and the <i>in trans</i> complemented strain Δ<i>mdxR+mdxR</i> (green) on starch (panel A), maltotetraose (panel B), maltose (panel C) and glucose (panel D) are shown. The growth curve of E1162 wild-type in M1 was shown in grey as a negative control. Overnight cultures were inoculated at an initial OD<sub>660</sub> of 0.0025 into 300 µl semi-defined minimal medium M1 [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0072285#B9" target="_blank">9</a>], M1 supplemented with 2.5 g/l of starch, maltotetraoise, maltose or glucose as sole carbon source, respectively, and then incubated in the Bioscreen C system at 37° C with continuous shaking. The absorbance of 600nm (A<sub>600</sub>) was recorded every 15 min for 12 hours. Growth curves are mean data of three independent experiments. Note that A<sub>600</sub> at the start of the experiment is higher in M1 + starch than in the other conditions, due to increased turbidity of the medium containing starch.</p

    Schematic representation of the gene clusters involved in maltodextrin and maltose utilization of <i>E. faecium</i> E1162.

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    <p>Genes are represented by arrows (drawn to scale). Genes putatively encoding proteins involved in maltodextrin transport and/or metabolism are indicated in blue or in red. Genes predicted to be involved in the uptake and/or metabolism of maltose are indicated in green or in purple. The genes that encode putative transcriptional regulators are indicated in red or purple. The grey arrows represent the adjacent genes that are not predicted to be involved in maltodextrin or maltose utilization. Gene names, without the EfmE1162-prefix (omitted for reasons of space), are indicated in the arrows and the gene locus tags are indicated above or below the arrows. The homologs in <i>L. monocytogenes</i> EGD-e or in <i>E. faecalis</i> V583 are shown with corresponding colors above or below the gene clusters of <i>E. faecium</i>. The gene locus tags of the homologs are indicated in the arrows. Lines link the homologous genes with corresponding genes in <i>E. faecium</i> and amino acid identities are indicated.</p
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