Vibrio fischeri as a model of Bacterial Colonization

该研究的长期目标是了解人类与其微生物群在最初几分钟到几小时的相互作用中发生的复杂对话。这些关系，无论是致病的还是有益的，通常开始于粘膜表面，实验研究通常无法接近的部位。此外，它们通常支持由数百种微生物物种组成的复杂财团。在这些位点，细菌的表面特征与宿主识别的相应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。这种相同的细胞和分子“语言”是如何以不同的方式产生健康或疾病这两种相反的结果的？为了回答这个问题，面对人体内令人生畏的微生物复杂性，使用更简单的模型系统，更适合实验操作。生物学家使用这样的系统来发现基本原理，揭示单个细菌物种如何成功地与其宿主相关联。其中一种模式是生物发光革兰氏阴性细菌费氏弧菌（Vibrio fischeri）与其鱿鱼宿主Euprymna puripopes之间的二元共生。与人类一样，鱿鱼与这种细菌的关系在每一代都开始了新的阶段，微生物从环境转变为功能性的有益关系。在这两种情况下，都会发生一种“筛选”，这种筛选只会促进与通过复杂分子相互作用识别的环境细菌的一小部分的联系。在鱿鱼弧菌系统中，这个过程发生在几分钟到几个小时内，并且可以直接对其进行完整成像。因此，该系统提供了难得的机会，以高的时间和空间分辨率来破译相互的分子和生物化学对话，这对于自然协会的正常发展至关重要。该项目汇集了一组具有细胞和发育生物学、生物化学和遗传学专业知识的科学家，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，以促进伴侣识别和特异性; 2）表征共生体的遗传因子，这些遗传因子对选择过程至关重要;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.