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. ***
