Sensing more than a quorum: The role of pheromones in the light-organ symbiont Vibrio fischeri

植物和动物一直被细菌定植，这些共生微生物经常对宿主的有益过程和/或疾病做出贡献。许多共生细菌使用信息素信号进行交流，使它们能够在感染期间协调群体行为。这种信息素信号通常被称为“群体感应”，因为高细胞密度是信息素积累所必需的。然而，法定人数是多少？通常不足以完全诱导信息素介导的行为，而且细菌信息素不是简单的人口普查信号。重要的是，信息素还可以在细菌之间交流宿主环境的各个方面。本项目将利用遗传、分子、显微和微生物学的方法，利用费氏弧菌与其自然寄主乌贼的易驯化共生模式，研究寄主条件与共生体--S信息素的使用之间的关系。信息素信号是在费氏弧菌中发现的，它仍然是此类研究中最被理解的模型系统之一。共生感染发生在只有费氏弧菌定植的透明组织中，感染过程中信息素的信号导致细菌发出生物发光，使感染相对简单，调控输出易于监测。该项目的科学目标是确定宿主环境的哪些方面导致细菌生物发光的诱导，并确定信息素在宿主内的通信条件中扮演什么角色。第三个目标是将细菌-宿主共生的研究整合到本科教育中，既通过研究中的直接再现，也通过生成材料来促进科学论文的课堂讨论。该项目将提供对共生细菌在宿主中遇到的环境的洞察，以及它们对宿主环境的感知如何与它们对信息素的使用相结合。该项目还将有助于培养年轻的科学家。

Plants and animals are consistently colonized by bacteria, and thesesymbiotic microorganisms often contribute to beneficial processes and/or diseasein their hosts. Many symbiotic bacteria communicate using pheromone signals,allowing them to coordinate group behaviors during infection. Such pheromonesignaling is typically called ?quorum sensing?, because high cell density isnecessary for pheromones to build up. However, a ?quorum? is typically notsufficient to induce pheromone-mediated behaviors fully, and bacterialpheromones are not simply census-taking signals. Importantly, the pheromonesmay also function to communicate aspects of the host environment among thebacteria. This project will use genetic, molecular, microscopic, and microbiologicalapproaches in exploiting the tractable model symbiosis between thebacterium Vibrio fischeri and its natural host squid Euprymna scolopes toexamine the relationship between conditions in the host and the symbiont?s useof pheromones. Pheromone signaling was discovered in V. fischeri and itremains among the best-understood model systems for such study. Thesymbiotic infection occurs in transparent tissue that is only colonized by V.fischeri, and pheromone signaling during infection results in the emission ofbioluminescence by the bacteria, making the infection relatively simple and theregulatory output easy to monitor. The scientific aims of this project are todetermine what aspects of the host environment lead to the induction of bacterialbioluminescence and to determine what role pheromones play in communicatingconditions in the host. A third aim is to integrate research on bacteria-hostsymbioses into undergraduate education, both through direct emersion inresearch and through the generation of materials to facilitate in-class discussionof scientific papers. The project will provide insight into the environmentsymbiotic bacteria encounter in a host, and how their perception of the hostenvironment can be integrated with their use of pheromones. The project willalso help train young scientists.