Project description:Bacterial persisters are a small proportion of phenotypically heterogeneous variants with the transient capability to survive in high concentrations of antibiotics, causing recurrent infections in both human and aquatic animals. Transfer-messenger RNA (tmRNA), which was encoded by the <i>ssrA</i> gene, was identified as a determinant regulator mediating the persistence to β-lactams in the pathogenic <i>Aeromonas veronii</i> C4. The deletion of tmRNA exhibited the increased ability of persister formation most probably due to the reduction of protein synthesis. Transcriptomic and metabolomic analyses revealed that the absence of tmRNA not only significantly elevated the intercellular levels of metabolite GlcNAc and promoted NaCl osmotic tolerance, but also upregulated the expression of metabolic genes in both the upstream biosynthesis pathway and the downstream metabolic flux of peptidoglycan (PG) biosynthesis. Finally, exogenous GlcNAc stimulated significant bacterial growth, enhanced content of GlcNAc in the cell wall, higher resistance to osmotic response, and higher persistence to cefotaxime in a concentration-dependent manner, implying its potential role in promoting the multiple phenotypes observed in tmRNA deletion strains. Taken together, these results hint at a potential mechanism of persister formation mediated by tmRNA against the β-lactam challenges in <i>A. veronii</i>.
Project description:To elucidate the target genes of ArgR in Aeromonas veronii, we engineered an Aeromonas veronii strain that expresses the ArgR protein fused to a 3× FLAG tag, and FLAG antibodies were employed for the immunoprecipitation of DNA-protein complexes.
Project description:The intestinal epithelial gene responses to Aeromonas veronii infection and the pathogenic mechanisms were investigated by comparative differential expression analysis
Project description:<p>Bacterial persisters refer to a small proportion of phenotypically heterogeneous variants with transient capability for survival when exposing to high concentrations of antibiotic, which constitute the major cause for recurrent infections both in human and aquatic infections. In pathogenic bacteria Aeromonas veronii, tmRNA (transfer-messenger RNA), the core factor of trans-translation system, was identified as a determinant regulator mediating the persistence to β-lactams. Compared with the wild type, the deletion of tmRNA exhibited unchanged growth rate, sustained susceptibility to cefotaxime, but did increase persister cell formation. Transcriptomic and metabolomic analyses revealed that, the absence of tmRNA not only upreglated the expressions of metabolic genes especially in the metabolic flux of peptidoglycan biosynthesis, but also significantly elevated the intercellular level of metabolite GlcNAc, thereby intensifying the contents of peptidoglycans in the cell wall. Eventually, exogenous GlcNAc stimulated significantly the bacterial growth and persistence to cefotaxime in a concentration dependent manner. Taken together, these results uncover a novel mechanism of persister formation mediated by tmRNA against the β-lactam challenges.</p>
Project description:The bacterium Aeromonas veronii is a co-pathogenic species that can negatively impact the health of both humans and aquatic animals. In this study, we used single-cell transcriptome analysis (scRNA-seq) to investigate the effects of infection with A. veronii on head kidney cells and the regulation of gene expression in the dark sleeper (Odontobutis potamophila). scRNA-seq was used to assess the effects of infection with A. veronii in O. potamophila B cells, endothelial cells, macrophages, and granulocytes, and differential enrichment analysis of gene expression in B cells and granulocytes was performed. The analyses revealed a significant increase in neutrophils and decrease in eosinophils in granulocytes infected with A. veronii. Activation of neutrophils enhanced ribosome biogenesis by up-regulating the expression of rps12 and rpl12 to fight against invading pathogens. Crucial pro-inflammatory mediators il1b, ighv1-4, and the major histocompatibility class II genes mhc2a and mhc2dab, which are involved in virulence processes, were up-regulated, suggesting that A. veronii activates an immune response that presents antigens and activates immunoglobulin receptors in B cells. These cellular immune responses triggered by infection with A. veronii enriched the available scRNA-seq data for teleosts, and these results are important for understanding the evolution of cellular immune defense and functional differentiation of head kidney cells.
Project description:In this study we used Illumina RNA-seq to identify genes expressed by A. veronii in mid-log phase growth in a rich medium and within the digestive tract of the medicinal leech. Our results shed light on the physiology of A. veronii during colonization of the leech gut. A comparison of Illumina RNA-seq of A. veronii in vivo versus in vitro.
Project description:Here, we report the use of Illumina RNA-Seq for investigating the physiology of the digestive-tract microbiome within the medicinal leech, Hirudo verbana. About 12 million cDNA reads were mapped against the genomes of the two dominant members of this simple microbiome. Results suggested that the most abundant, yet uncultured Rikenella-like bacterium forages host mucin glycans and ferments the carbohydrates to acetate that is secreted into the environment. The second dominant symbiont, Aeromonas veronii, appears to utilize the acetate secreted by Rikenella as a carbon and energy source, possibly linking the physiologies of the dominant symbionts. This study demonstrates how RNA-seq can be used to reveal the physiology of a naturally occurring microbiome.
