Project description:The Sfh protein is encoded by self-transmissible plasmids involved in human typhoid and is closely related to the global regulator H-NS. We have found that Sfh provides a stealth function that allows the plasmids to be transmitted to new bacterial hosts with minimal effects on their fitness. Introducing the plasmid without the sfh gene imposes a mild H-NS- phenotype and a severe loss of fitness due to titration of the cellular pool of H-NS by the A+T-rich plasmid. This stealth strategy seems to be used widely to aid horizontal DNA transmission and has important implications for bacterial evolution.
2007-01-15 | E-SGRP-7 | biostudies-arrayexpress
Project description:Transmission of social spider symbionts
Project description:Host-microbe interactions are virtually bidirectional, benefiting both the host and microbial sides. It is becoming increasingly recognized the influence of the microbe on many aspects of host physiology and diseases, but whether/how the host affects their symbionts is poorly characterized. Here, we reported that the host acts as a critical factor to shape the lifestyle of their symbionts in the Drosophila and bacteria model system. First, we observe that Drosophila larvae play a pivotal role in competing with pathogenic symbionts in the co-existing niche. More specifically, host larvae antagonize symbionts by deconstructing the surface slick, preventing outgrowth and antagonizing the pathogenicity of S. marcescens. Furthermore, Drosophila larvae cause the shift in the transcriptomic profile of S. marcescens, characterized with the upregulated expression of genes related to bacterial proliferation and growth and the downregulated expression of genes related to bacterial pathogenicity. More importantly, advances in bacterial single-cell RNA sequencing provide opportunities to reveal transcriptional variation, including toxic factors, across individual cells and a subpopulation clustering of isogenic bacterial populations. Finally, we found that AMPs from larvae recapitulated the response of S. marcescens to the presence of Drosophila larvae. Altogether, these findings provide an insight into the pivotal roles of the host in influencing the potential pathogens' lifecycle switching from commensalism to pathogenicity, opening the door to a better understanding of the ecological relationships between the host and microbe.
Project description:Host-microbe interactions are virtually bidirectional, benefiting both the host and microbial sides. It is becoming increasingly recognized the influence of the microbe on many aspects of host physiology and diseases, but whether/how the host affects their symbionts is poorly characterized. Here, we reported that the host acts as a critical factor to shape the lifestyle of their symbionts in the Drosophila and bacteria model system. First, we observe that Drosophila larvae play a pivotal role in competing with pathogenic symbionts in the co-existing niche. More specifically, host larvae antagonize symbionts by deconstructing the surface slick, preventing outgrowth and antagonizing the pathogenicity of S. marcescens. Furthermore, Drosophila larvae cause the shift in the transcriptomic profile of S. marcescens, characterized with the upregulated expression of genes related to bacterial proliferation and growth and the downregulated expression of genes related to bacterial pathogenicity. More importantly, advances in bacterial single-cell RNA sequencing provide opportunities to reveal transcriptional variation, including toxic factors, across individual cells and a subpopulation clustering of isogenic bacterial populations. Finally, we found that AMPs from larvae recapitulated the response of S. marcescens to the presence of Drosophila larvae. Altogether, these findings provide an insight into the pivotal roles of the host in influencing the potential pathogens' lifecycle switching from commensalism to pathogenicity, opening the door to a better understanding of the ecological relationships between the host and microbe.
Project description:To determine the optimal RNA-Seq approach for animal host-bacterial symbiont analysis, we compared transcriptome bias, depth and coverage achieved by two different mRNA capture and sequencing strategies applied to the marine demosponge Amphimedon queenslandica holobiont, for which genomes of the animal host and three most abundant bacterial symbionts are available.
Project description:The mammalian gastrointestinal tract harbors thousands of bacterial species that include symbionts as well as potential pathogens. The immune responses that limit access of these bacteria to underlying tissue remain poorly defined. In this study, we used microarrays to uncover the transcriptional responses that occur in small intestinal γδ intraepithelial lymphocytes following bacterial challenge.
Project description:au11-03_gravite - action of microgravity on root development - Action of microgravity on root development - Arabidopsis were grown on horizontal or vertical clinostat for 4, 8 or 12 days. Seedlings on horizontal clinostat were in simulated microgravity and seedlings on vertical clinostat are considered as a control. Comparison was made between plants grown on simulated microgravitry and vertical position.
Project description:Plasmid maintenance costs to bacterial hosts is closely linked to the mechanisms that underlie plasmid fitness and how these costs are resolved. Herein, we performed multiple (63) serial passage to explore the compensatory mechanisms of co-evolution of multidrug-resistant IncHI2 plasmid pJXP9 and S. Typhimurium strain ATCC 14028 with or without antibiotic selection. pJXP9 could be maintained at for hundreds of generations even without drug exposure. Decreased lag times and higher competitive advantages were observed in end-point evolved strains bearing pJXP9 compared to ancestral strains. Genomic and transcriptomic analyses revealed that the fitness costs of pJXP9 in ATCC 14028 were derived from not only specific plasmid genes, particularly the multidrug-resistant region and conjugation transfer region I, but also the conflicts resulting from chromosomal gene interactions. Correspondingly, plasmid-borne deletions of these regions could compensate the fitness cost due to the presence of the plasmid. Furthermore, mutations and mRNA alterations in chromosomal genes involved in physiological functions were also adaptative. These functions included decreased flagellar motility, oxidative stress resistance and fumaric acid synthesis, and increased Cu resistance. Our findings suggest that plasmid maintenance through plasmid-bacteria co-evolution is a trade-off between increasing plasmid vertical transmission and impairing its horizontal transmission and bacterial physiological phenotypes.