Meeting Abstract

18.2  Sunday, Jan. 4  Variation in gene expression profiles among bacterial symbionts from squids of the family Loliginidae (Mollusca: Cephalopoda) GUERRERO-FERREIRA, Ricardo*; GORMAN, Clayton; NISHIGUCHI, Michele; New Mexico State University ricardo@nmsu.edu

Luminescent bacteria in the family Vibrionaceae (Bacteria:Gamma-Proteobacteria) are commonly found in complex, bilobed light organs of squids in the families Sepiolidae and Loliginidae. These organs are of similar morphology in both families of squids, but species of bacteria inhabiting each host are different. Previous research provided evidence of a non species-specific association between sepiolid and loliginid squids and Vibrionaceae bacteria including the pathogenic bacterium Vibrio harveyi. This suggests that specificity for the Vibrio genus exists, but may be influenced by additional factors besides host species. We investigated differences in gene expression profiles between bacteria grown in their free-living state (seawater) or their symbiotic state (light organ) in an effort to establish which genes are co-opted for metabolic functions required for symbiosis in Vibrio harveyi. Genes that are exclusively expressed in the loliginid light organs encode for proteins such as cell wall-associated hydrolases, outer membrane, putative transporters (YaaJ, gamma-glutamyltransferease and transglycosylase C) and transcriptional regulators of the LysR family. Comparison of gene expression profiles between symbiotic and free-living states will provide a better understanding of the factors that are responsible for specificity, establishment, and maintenance of the association. Combining data from this study with similar studies on sepiolid symbionts will also illustrate whether bacteria are selecting for a generalist evolutionary path for host colonization, and if those mechanisms are similar amongst two different families of host squids.