Meeting Abstract

20.6  Thursday, Jan. 3  The roles of UDP-glucose-6-dehydrogenase and mshA are responsible for colonization of sepiolid (Cephalopoda: Sepiolidae) light organs. ARIYAKUMAR, D.; NISHIGUCHI, M.K.*; New Mexico State University, Las Cruces donsanji@nmsu.edu

Mutualistic associations between the sepiolid squid Euprymna tasmanica (Mollusca: Cephalopoda) and its luminescent bacterium, Vibrio fischeri have been extensively studied as a model to understand gene expression, phylogeography, and cospeciation. Juvenile squids lack symbiotic bacteria, but obtain their Vibrio symbionts from the environment within a few hours after hatching. Although this colonization event is specific for V. fischeri, symbiotic bacteria must overcome several obstacles to successfully attach and colonize the light organ. Here we examine the effects of two possible symbiotic genes that are responsible for initial attachment and biofilm formation in squid light organs. Uridine diphospahte-6-dehydrogenase (UDPDH) and mannose sensitive hemagglutinin (mshA) mutants were generated in V. fischeri using single recombinant techniques to determine whether each gene has an effect on host colonization, specificity and biofilm formation. Mutant strains were also complemented with appropriate genes to regain loss of function and competency was tested both in vitro an in na�ve juvenile squids. Biofilm assays were executed with both mutant and complement strains to determine whether either of these genes were important the formation of bacterial biofilms. Squid light organ colonization assays and transmission electron microscopy (TEM) confirmed differences in host colonization between the wild-type and mutant strains. These findings demonstrate the importance of both UDPDH and mshA gene expression for successful light organ colonization by V. fischeri, and furthers our understanding of host specificity in this environmentally transmitted symbiosis.