Meeting Abstract

50.5  Saturday, Jan. 5  Genetic switches control host specificity in a squid-Vibrio symbiosis CHAVEZ, A.A.; GORMAN, C.*; LOSTROH, C.P.; NISHIGUCHI, M.K.; New Mexico State University; New Mexico State University; Colorado College; New Mexico State University nish@nmsu.edu

Gap repair is a technique that has historically been used to clone entire operons by using the natural recombinant homologous cloning mechanism in Saccharomyces cerevisiae. By using S. cerevisiae in vivo recombination, we can manipulate and express operons from different Vibrio fischeri strains from geographically distinct squid host populations to determine if suites of genes are responsible for the specificity observed among closely related host-symbiont pairs. V. fischeri ES114 genomic DNA (isolated from Euprymna scolopes, a Hawaiian squid host) was then used as the nucleotide template; the targeted operon and the gapped vector was digested and simultaneously introduced into yeast cells allowing recombination. V. fischeri can then be transformed with the new vector by tri-parental mating to contain entire operons/regulons from the other strain, in this case V. fischeri ETJB1H (isolated from E. tasmanica, an Australian squid host). This technique allowed us to execute a detailed investigation of the importance in strain-specificity of these gene operons in vivo. Subsequently, two different squid host species (E. scolopes and E. tasmanica) were used to test colonization abilities and competition of the constructed strains. Results indicate that after mobilizing lux and pil operons from ETJB1H to ES114, colonization of the constructed strain was equivalent to the efficiency observed for the native strain; the same was observed for the msh operon, but in this case after mobilization from ES114 to ETJB1H. Thus, competitive ability based on symbiotic loci is not equal among closely related strains of Vibrio. Deciphering how the evolutionary history of specificity between closely related Vibrio strains occurred may give insight to the function of competence and inter-strain genetic specificity.