Marine BioTech Post-doc: Coevolution In A Luminous Bacterium-Squid Symbiosis

9321645红宝石生物发光海洋细菌，费氏弧菌，是海鞘鱿鱼属Euprymna和Sepiola的发光器官共生体。细菌对发育中的发光器的定植导致费氏弧菌菌株的一个特定亚群(或亚种)建立了成功的联系。该项目将研究来自两个地点的几种重叠的海鞘乌贼种群，并将确定这些种群是否是宿主特有的。通过对寄主和共生体DNA的PCR扩增、限制性片段长度多态性(RFLP)和序列分析，可以推断不同菌株之间以及海鞘鱿鱼种之间的系统发育关系。在进行分子系统发育分析的同时，还将完成交叉定植实验，以确定共生菌是否能够在其他寄主物种中发起定植。在宿主物种以外的动物上定居的菌株将接受程度、成功程度和与自然共生菌株的竞争优势的测试。该模型是已知的唯一一种宿主和共生体都可以成功地相互独立培养的动物/细菌共生体，并提供了一个独特的实验系统来研究进化在共生体中的作用。***

9321645 Ruby Bioluminescent marine bacteria of the species, Vibrio fischeri, are the light organ symbionts of the sepiolid squid genera Euprymna, and Sepiola. Bacterial colonization of the developing light organ results in the establishment of a successful association by one specific subset (or subspecies) of Vibrio fischeri strains. This project will examine populations of V. Fischeri in several overlapping species of sepiolid squid from two locations, and will determine whether these populations of V. fischeri are host specific. Through the use of PCR amplification, restriction fragment length polymorphism (RFLP), and sequence analysis of both host and symbiont DNA, the phylogenetic relationships both among various strains of V. fischeri and among sepiolid squid species will be inferred. Along with the molecular phylogenetic analysis, cross- colonization experiments will be completed to determine whether the symbiotic bacteria are able to initiate any colonization in other host species of squid. Strains that colonize animals other than their host species, will be tested for the degree, success, and competitive dominance with the natural symbiotic strain. This model is the only known type of animal/bacterial symbioses where both host and symbiont can be cultured successfully and independently from one another, and provides a unique experimental system to address the role of evolution in symbioses. ***