Xenorhabdus Mutualsim and Pathogenesis: Temporal Regulation and Function of Symbiosis Factors

在共生关系中，动物，包括人类，与细菌相互作用，可能有益或有害。目前，细菌对不同宿主环境的适应如何决定特定微生物是否会产生益处或危害的知识有限，尽管这些知识在预防或促进特定细菌相互作用方面具有重要意义。 这项研究的重点是了解细菌如何感知和响应不同的宿主环境，以启动有益或有害性状的表达。正在研究的细菌在与小的土栖蛔虫（线虫）结合时表现出有益的特性，而在与昆虫幼虫结合时表现出毒性特性。 作为其自然生命周期的一部分，线虫将细菌传播（载体）到昆虫幼虫中。在这种新的环境中，细菌表现出毒性特征，并杀死昆虫。然后昆虫尸体作为线虫和细菌繁殖和进一步传播的营养源。这项研究将研究当细菌在不同的动物宿主之间移动时，协调和调节有益和有害性状表达的复杂分子电路。这项研究揭示的范式将为以下问题提供广泛的见解：细菌对新环境的适应如何改变共生行为，以及媒介传播的致病细菌在媒介传播过程中如何适应？这项研究的结果将通过社区研讨会和高中外展计划向公众公布和传播。 本科生，研究生和博士后学生将通过直接的科学探究在分子生物学，线虫学，昆虫学和细菌学领域进行培训。 因此，该项目将提供细菌与动物宿主相互作用的基础知识，并将培养未来的科学家进一步应用这些知识的专业知识。

In symbiotic associations animals, including humans, interact with bacteria that can be either beneficial or harmful. Currently there is limited knowledge of how bacterial adaptation to different host environments dictates whether a particular microbe will cause benefit or harm, despite the important implications of such knowledge in preventing or promoting specific bacterial interactions. This research focuses on understanding how bacteria sense and respond to different host environments to initiate expression of either beneficial or harmful traits. The bacterium being studied expresses beneficial traits when it is associated with a small soil-dwelling roundworm (nematode), and expresses virulence traits when it is associated with insect larvae. As part of its natural life cycle, the nematode transmits (vectors) the bacterium into the insect larva. In this new environment, the bacterium expresses virulence traits, and kills the insect. The insect cadaver then serves as a nutrient source for reproduction and further dissemination of both the nematode and bacteria. This research will examine the complex molecular circuitries that coordinate and regulate the expression of beneficial and harmful traits as the bacteria move between different animal hosts. The paradigms revealed by this research will provide broad insights into such questions as: how does bacterial adaptation to new environments alter symbiotic behavior, and how do vector-borne disease-causing bacteria adapt during transmission by the vector? The results of this research will be published and disseminated to the public through community seminars and high school outreach programs. Undergraduate, graduate, and post-doctoral students will be trained in areas of molecular biology, nematology, entomology, and bacteriology through direct scientific inquiry. Thus, this project will provide fundamental knowledge of bacterial interactions with animal hosts, and will train future scientists with the expertise to further apply this knowledge.