Meeting Abstract
The beneficial bioluminescent marine bacterium Vibrio fischeri has been used to study mechanisms of symbiont specificity, host recognition, and evolutionarily driven trade-offs in environmentally transmitted associations with animal hosts (Cephalopoda: Sepiolidae). V. fischeri bacteria colonize the squid light organ where bacterial bioluminescence is produced in order to provide the squid with the ability to counterilluminate. Given that many of the regulatory elements in V. fischeri are controlled by the host environment, understanding how such cross talk occurs in vivo will shed light on bacterial-host interactions. Therefore, we investigated the feasibility of using chitin induced natural transformation in V. fischeri to introduce linear ds DNA expression cassettes, which are designed to integrate at targeted sequences within the V. fischeri genome via homologous recombination. This technique is ideally suited to determining host specificity and other aspects of symbiosis. We initially targeted the luxA gene within the lux operon, which is responsible for generating the luciferase-based bioluminescence produced by V. fischeri. Using a targeted insertional knock-out of the luxA gene along with an insertional complement of luxA, we can study the regulation and modulation of bioluminescence production in the dialog between host and symbiont, which allows for a stable, beneficial association. The on-going development of efficient genetic modification techniques are a vital link in understanding the interdependent connections between host species and their symbionts.
