Meeting Abstract

P2.86  Monday, Jan. 5  Genetic temporal change in the bacterial symbiont Vibrio fischeri isolated from natural host squid populations of Euprymna tasmanica (Mollusca: Cephalopoda) GUTIERREZ, J.*; SOTO, W.; NISHIGUCHI, M.K.; New Mexico State University nish@nmsu.edu

Vibrio fischeri is a bioluminescent bacterial symbiont of sepiolid squids (Cephalopoda: Sepiolidae) and monocentrid fishes (Actinopterygii: Monocentridae). Vibrio bacteria are transmitted environmentally; that is, they are obtained from the surrounding seawater subsequent to hatching. The infection is highly specific; only species from the genera Vibrio are capable of fully infecting E. tasmanica juveniles. Previous results have shown that although this association is stable, numerous V. fischeri strains are capable of infecting populations of the same species of sepiolid from different biogeographic locations. Thus, in an effort to provide insight into the factors that drive the evolution and biogeography of this symbiosis, we have isolated V. fischeri from E. tasmanica collected from the same wild populations between 2000 and 2008. Genomic DNA was extracted from these isolates and analyzed by PCR amplification and sequencing of the glyceraldehyde phosphate dehydrogenase subunit A (gapA) locus. Identification of population changes with this nine-year span represents over 16,000 bacterial generations. Results obtained from our analysis provide detailed information regarding the rate at which evolution has occurred in natural populations of symbiotic V. fischeri. Thus, our findings will establish a baseline that can be incorporated in future genetic analyses of symbiotic strains experimentally evolved under various abiotic conditions such as salinity and temperature that mimic ecological parameters found in nature, allowing further predictions of speciation in the Vibrionaceae.