MCFALL-NGAI, M.J.; KIMBELL, J.R.: The Euprymna scolopes-Vibrio fischeri symbiosis: From genes to demes

The monospecific light organ association between the Hawaiian sepiolid squid Euprymna scolopes and the marine luminous bacterium Vibrio fischeri has been used as a model for the study of the most common type of animal-bacterial interaction, i.e., the association of coevolved Gram-negative bacteria with the extracellular apical surfaces of polarized epithelia. Analysis of the squid-vibrio symbiosis has spanned from characterizations of the harvesting mechanisms by which the host ensures colonization by the appropriate symbiont to identification of bacteria-induced changes in host gene expression that accompany the establishment and maintenance of the relationship. Studies of this model have been enhanced by extensive collaboration with microbiologists, who have established genetics in the bacterial symbiont. The results of our studies have indicated that initiation and persistence of the association requires a complex, reciprocal molecular dialogue between these two phylogenetically disparate partners. In addition, many of our data suggest that similar genes are used to modulate both beneficial and pathogenic associations, calling into question the source of the selection pressure on genes heretofore assumed to be involved solely in responses to virulence determinants of bacteria. Supported by NSF IBN 9904601 and NIH RR12294.