Marine Biotech Fellowship: Molecular Analysis of Bacterial Genes Involved in Establishing the Vibrio Fischeri/Euprymna Scolopes Symbiotic Relationship

[9212452] GILSON这个项目的长期目标是了解建立细菌/动物共生关系的机制。费氏弧菌既可以作为一种自由生活的海洋细菌存在，也可以作为鱿鱼和单心鱼的光器官的生物发光居民存在。V. fischeri和小鱿鱼Euprymna scolopes的关联提供了一种互惠关系的模型，并且已经被证明是符合实验室和分子遗传学方法的。本项目旨在鉴定费氏弧菌感知和响应宿主体内条件时表达的基因和基因产物。只有当细菌与鱿鱼结合时才表达的基因将通过与一个基因的融合来识别，该基因的表达对细菌在宿主内的生存至关重要，但在选择性条件下，在宿主外是致命的。蛋白质凝胶（2-D）将用于识别在这两种不同环境中优先合成的蛋白质。由于生物发光在共生条件下优先表现出来，并由一种依赖于密度的信息素类分子控制，因此其他也是该调节的一部分的基因将通过混合融合技术被识别出来。从表面上看，fischeri和scopes的关系是一种共生关系，但从进化的角度来看，这种关系的建立和维持与共生、寄生和致病相关。细胞-细胞通讯、信号转导和基因激活机制的遗传基础信息将适用于所有这些系统。＊＊＊

9212452 GILSON The long term objective of this project is to understand the mechanisms involved in establishing a bacterial/animal symbiosis. Vibrio fischeri exists both as a free-living marine bacteria and as a bioluminescent inhabitant of the light organ of sepiolid squid and monocentrid fish. The association of V. fischeri and the small squid, Euprymna scolopes, offers a model mutualistic relationship and has already proven to be amenable to laboratory and molecular genetic methodologies. This project is directed at identifying the genes and gene products that are expressed as V. fischeri senses and responds to the conditions within the host. Genes that are expressed only when the bacteria is in association with the squid will be identified by fusions with a gene whose expression is essential for bacterial survival within the host, but, under selective conditions, is lethal outside the host. Protein gels (2-D) will be used to identify proteins that are preferentially synthesized in these two different environments. And since bioluminescence is preferentially exhibited under symbiotic conditions and is controlled by a density-dependent, pheromone-like molecule, other genes that are also part of this regulon will be identified through mudlac fusion technology. The relationship between V. fischeri and E. scolopes is apparently a mutualistic one, however its establishment and maintenance is evolutionarily related to commensal, parasitic and pathogenic associations. Information of the genetic basis for mechanisms of cell-cell communications, signal transduction and gene activation will be applicable to all of these systems. ***