INTERACTION BETWEEN X NEMATOPHILUS AND ITS HOSTS

描述（改编自申请人的摘要）：本提案旨在了解细菌如何与其真核宿主相互作用以及营养物质的可用性如何影响这些相互作用。细菌嗜热短杆菌提供了宿主微生物相互作用的有价值的模型系统：它是寄生在线虫Steinernema carpocapsae肠道中的共生体，也是杀死幼虫期昆虫的病原体。本研究的目标是确定X使用的分子机制。介导宿主相互作用。许多革兰氏阴性菌缺乏营养会引发对压力的抵抗力增强和毒力决定因素的产生。该响应部分地由特定的σ因子ss调节。该建议的第一个具体目标是分析ss和ss依赖性基因表达在X的共生和致病性中的作用。与其真核宿主。这项工作的结果将开始解决遗传调控的生存和适应在X。并将提供深入了解营养物质的可用性如何影响宿主细菌的相互作用。X.嗜热菌可能已经进化出多种调节机制，包括饥饿反应，介导宿主相互作用。虽然具体目标1完全集中在饥饿反应上，但具体目标2的目标是进行遗传测试，以确定介导X之间共生的其他细菌调节机制。嗜线虫和线虫。目标是获得和表征X。不再保留在线虫肠囊泡内的嗜线虫突变体。这项工作将提供深入了解的基因和基因产物是必不可少的共生关系，并将有助于阐明宿主相互作用在X。嗜热菌和其他细菌。

DESCRIPTION (Adapted from the Applicant's Abstract): This proposal is aimed at understanding how bacteria interact with their eukaryotic hosts and how the availability of nutrients affects these interactions. The bacterium Xenorhabdus nematophilus provides a valuable model system of host microbe interactions: it is a symbiont that resides in the intestine of the nematode Steinernema carpocapsae and a pathogen that kills larval stage insects. The goals of this research are to identify the molecular mechanisms used by X. nematophilus to mediate host interactions. Nutrient deprivation in many Gram-negative bacteria triggers development of increased resistance to stress and the production of virulence determinants. This response is partially regulated by a specific sigma factor, ss. The first specific aim of this proposal is to analyze the role of ss and ss-dependent gene expression in the symbiosis and pathogenicity of X. nematophilus with its eukaryotic hosts. The results of this work will begin to address the genetic regulation of survival and adaptation in X. nematophilus and will provide insight into how the availability of nutrients affects host-bacterium interactions. X. nematophilus is likely to have evolved multiple regulatory mechanisms, including the starvation response, that mediate host interactions. While specific Aim 1 focuses entirely on the starvation response, the goal of Specific Aim 2 is to perform genetic tests to identify additional bacterial regulatory mechanisms that mediate symbiosis between X. nematophilus and the nematode. The goal is to obtain and characterize X. nematophilus mutants that are no longer retained within the intestinal vesicles of nematodes. This work will provide insight into the genes and gene products that are essential for symbiosis and will aid in the elucidation of the regulation of host interactions in X. nematophilus and other bacteria.