Vibrio fischeri as a model of Bacterial Colonization

描述(由申请人提供)：拟议研究的长期目标是了解在最初几分钟到几个小时的相互作用中，人类与微生物群之间发生的复杂对话。这些关系，无论是致病的还是有益的，通常都始于粘膜表面，而这些部位往往是实验研究无法接触到的。此外，他们通常支持一个由数百个微生物物种组成的复杂联盟。在这些位置，细菌的表面特征和相应的宿主识别机制之间的相互作用控制着有益和致病关联的启动和持续。同样的细胞和分子‘语言’如何被不同地使用来产生健康或疾病的两种相反的结果？为了回答这个问题，面对人体内令人望而生畏的微生物复杂性，使用了更容易进行实验操作的更简单的模型系统。生物学家使用这样的系统来发现揭示单个细菌物种如何与其宿主成功结合的基本原理。一种这样的模式是生物发光革兰氏阴性细菌费氏弧菌与其鱿鱼宿主Euprymna scolope之间的二元共生。与人类一样，鱿鱼与这种细菌的关系每一代都会有新的开始，随着微生物从环境过渡到功能上的有益关系。在这两种情况下，都会发生“筛选”，只促进与通过复杂的分子相互作用识别的那一小部分环境细菌的联系。在鱿鱼弧菌系统中，这个过程需要几分钟到几个小时的时间，并且可以直接完整地成像。因此，该系统提供了难得的机会，以高时间和空间分辨率破译相互的分子和生化对话，这对自然联系的正常发展至关重要。该项目汇集了一组在细胞和发育生物学、生物化学和遗传学方面具有专长的科学家，以解决以下具体目标：1)研究宿主细胞和特定共生体之间的相互作用如何塑造微环境，以促进伙伴识别和特异性；2)表征共生体对选择过程至关重要的遗传因素；以及3)确定细菌运动性和外膜囊泡(众所周知的毒力和定殖性决定因素)如何在宿主和共生体之间的对话中发挥关键作用。

DESCRIPTION (provided by applicant): The long-term objectives of the proposed research are to understand the complex dialogue that occurs between humans and their microbiota during the initial minutes to hours of their interaction. These relationships, whether pathogenic or beneficial, typically begin at mucosal surfaces, sites that are often inaccessible to experimental study. In addition, they usual support a complex consortium consisting of hundreds of microbial species. At these sites, the interplay between the surface features of bacteria and the corresponding mechanisms of host recognition controls the initiation and persistence of both beneficial and pathogenic associations. How is this same cellular and molecular 'language' used differently to produce the two opposite outcomes of health or disease? To answer this question in the face of the daunting microbial complexity in the human body, simpler model systems are used that are more amenable to experimental manipulation. Biologists use such systems to discover fundamental principles that reveal how an individual bacterial species associates successfully with its host. One such model is the binary symbiosis between the bioluminescent Gram-negative bacterium, Vibrio fischeri, and its squid host, Euprymna scolopes. As in humans, the squid's relationship with this bacterium begins a new each generation, with the microbe transitioning from the environment into a functional beneficial relationship. In both cases, a 'winnowing' occurs that promotes an association with only that small subset of environmental bacteria that are recognized through complex molecular interactions. In the squid-vibrio system, this process occurs over minutes to hours, and can be directly imaged in its entirety. As such, the system offers the rare opportunity to decipher, with high temporal and spatial resolution, the reciprocal molecular and biochemical dialogue that is essential for a natural association to develop normally. This project brings together a team of scientists with expertise in cell and developmental biology, biochemistry, and genetics, to address the following specific aims: 1) to examine how interactions between host cells and the specific symbiont shape the microenvironment to promote partner recognition and specificity; 2) to characterize the genetic factors of the symbiont that are essential to the selection process; and, 3) to define how bacterial motility and outer membrane vesicles, well known virulence and colonization determinants, play a key role in the dialogue between host and symbiont.