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1.
G. Larivière-Gauthier A. Thibodeau É. Yergeau P. Fravalo 《Letters in applied microbiology》2021,72(2):113-120
Recent studies have shown that Salmonella shedding status affects sows’ microbiota during gestation and that these modifications are reflected in the faecal microbiota of their piglets at weaning. The aims of this study were: (a) to evaluate the persistence, up to the fattening period, of the previously measured link between the microbiota of piglets and their mothers’ Salmonella shedding status; and (b) measure the impact of the measured microbiota variations on their Salmonella excretion at this stage. To achieve this, 76 piglets born from 19 sows for which the faecal microbiota was previously documented, were selected in a multisite production system. The faecal matter of these swine was sampled after 4 weeks, at the fattening stage. The Salmonella shedding status and faecal microbiota of these animals were described using bacteriological and 16S rRNA gene amplicon sequencing respectively. The piglet digestive microbiota association with the Salmonella shedding status of their sows did not persist after weaning and did not affect the risk of Salmonella excretion during fattening, while the birth mother still affected the microbiota of the swine at fattening. This supports the interest in sows as a target for potentially transferrable microbiota modifications. 相似文献
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Eugénie Bassères Giuseppe Coppotelli Thorsten Pfirrmann Jens B. Andersen Maria Masucci Teresa Frisan 《Cellular microbiology》2010,12(11):1622-1633
Invasion of eukaryotic target cells by pathogenic bacteria requires extensive remodelling of the membrane and actin cytoskeleton. Here we show that the remodelling process is regulated by the ubiquitin C‐terminal hydrolase UCH‐L1 that promotes the invasion of epithelial cells by Listeria monocytogenes and Salmonella enterica. Knockdown of UCH‐L1 reduced the uptake of both bacteria, while expression of the catalytically active enzyme promoted efficient internalization in the UCH‐L1‐negative HeLa cell line. The entry of L. monocytogenes involves binding to the receptor tyrosine kinase Met, which leads to receptor phosphorylation and ubiquitination. UCH‐L1 controls the early membrane‐associated events of this triggering cascade since knockdown was associated with altered phosphorylation of the c‐cbl docking site on Tyr1003, reduced ubiquitination of the receptor and altered activation of downstream ERK1/2‐ and AKT‐dependent signalling in response to the natural ligand Hepatocyte Growth Factor (HGF). The regulation of cytoskeleton dynamics was further confirmed by the induction of actin stress fibres in HeLa expressing the active enzyme but not the catalytic mutant UCH‐L1C90S. These findings highlight a previously unrecognized involvement of the ubiquitin cycle in bacterial entry. UCH‐L1 is highly expressed in malignant cells that may therefore be particularly susceptible to invasion by bacteria‐based drug delivery systems. 相似文献
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A new purification method for cytosolic malate dehydrogenases from several sources has been developed. The procedure, employing chromatographies on 5'AMP-Sepharose, DEAE-Sephacel and Blue-Sepharose, allows for a rapid isolation of the enzyme (approximately 40 hours), in large quantities, with good yields (45-54%). The specific activity of final preparations were around 1300 I.U./mg and were judged homogeneous by polyacrylamide gradient gel and sodium dodecyl sulfate polyacrylamide gel electrophoresis, high performance size exclusion chromatography and isoelectric focusing. 相似文献
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The succinate dehydrogenase consists of only four subunits, all nuclearly encoded, and is part of both the respiratory chain and the Krebs cycle. Mutations in the four genes encoding the subunits of the mitochondrial respiratory chain succinate dehydrogenase have been recently reported in human and shown to be associated with a wide spectrum of clinical presentations. Although a comparatively rare deficiency in human, molecularly defined succinate dehydrogenase deficiency has already been found to cause encephalomyopathy in childhood, optic atrophy or tumor in adulthood. Because none of the typical housekeeping genes encoding this respiratory chain complex is known to present tissue-specific isoforms, the tissue-specific involvement represents a quite intriguing question, which is mostly addressed in this review. A differential impairment of electron flow through the respiratory chain, handling of oxygen, and/or metabolic blockade possibly associated with defects in the different subunits that can be advocated to account for tissue-specific involvement is discussed. 相似文献
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Interaction of some polyhexamethylene biguanides and membrane phospholipids in Escherichia coli 总被引:6,自引:0,他引:6
The interaction between some polyhexamethylene biguanides and the cell envelope of Escherichia coli has been investigated. An amine-ended dimer, (AED, n = 2), a polydisperse mixture (ICI plc) available as the active ingredient of Vantocil IB, (PHMB, n = 5.5), and a high molecular weight fraction, (HMW, n = greater than or equal to 10) of PHMB were used. The sensitivity of batch cultures depleted of magnesium (M-dep), phosphorus (P-dep) or glycerol (C-dep) towards the biocides was assessed by monitoring the rate and extent of potassium ion leakage. P-dep suspensions were particularly resistant to all these agents and possessed less than half the quantity of phospholipid of other cell types. This was compensated for by a proportionate increase in fatty acid and neutral lipid content of the cells. The reduction in phospholipid content was accounted for by decreases in phosphatidylglycerol (PG) and phosphatidylethanolamine (PE). Diphosphatidylglycerol (DPG) and phosphatidylserine (PS) content of the cultures remained unaffected by the depleting nutrient. Fourier-transform n.m.r. spectroscopy was used to study proton nuclei during the interaction of HMW, AED and PHMB with various phospholipid-vesicle preparations. The results strongly suggest that the biocides acted preferentially on the acidic phospholipids PG and DPG, rather than towards PE or PS. Resistance of P-dep cultures therefore reflected reductions in PG content. A molecular basis for the interaction of these compounds and membranes is proposed. 相似文献
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Cloning and expression of the Erwinia chrysanthemi asparaginase gene in Escherichia coli and Erwinia carotovora 总被引:1,自引:0,他引:1
A genomic library of Erwinia chrysanthemi DNA was constructed in bacteriophage lambda 1059 and recombinants expressing Er. chrysanthemi asparaginase detected using purified anti-asparaginase IgG. The gene was subcloned on a 4.7 kb EcoRI DNA restriction fragment into pUC9 to generate the recombinant plasmid pASN30. The position and orientation of the asparaginase structural gene was determined by subcloning. The enzyme was produced at high levels in Escherichia coli (5% of soluble protein) and was shown to be exported to the periplasmic space. Purified asparaginase from E. coli cells carrying pASN30 was indistinguishable from the Erwinia enzyme on the basis of specific activity [660-700 units (mg protein)-1], pI value (8.5), and subunit molecular weight (32 X 10(3]. Expression of the cloned gene was subject to glucose repression in E. coli but was not significantly repressed by glycerol. Recombinant plasmids, containing the asparaginase gene, when introduced into Erwinia carotovora, caused increased synthesis of the enzyme (2-4 fold higher than the current production strain). 相似文献