Meeting Abstract
The bioluminescent marine bacterium Vibrio fischeri has been used to study mechanisms of environmental specificity in mutualistic associations with animal hosts. V. fischeri colonizes the interior of the light organ of sepiolid squids (Cephalopoda: Sepiolidae) and produces luciferase based light which provides ventral counter-shading camouflage for the squid. Stressful conditions, such as low O2 and pH levels may develop within the colonized light organ as a result of V. fischeri growth. Thus, beneficial adaptations to such stressful conditions may provide V. fischeri a competitive advantage in colonizing the light organ. We are investigating the feasibility of assaying the pH within the colonized light organ of the Hawaiian bobtail squid, Euprymna scolopes in order to determine if V. fischeri is adapted to thrive in a low pH environment. We have developed a series of plasmids containing pH sensitive green fluorescent protein (pH-GFP) derivatives, which, when expressed by V. fischeri colonizing the light organ, will produce an emission spectrum wavelength profile that correlates with pH, both within V. fischeri and in the lumen of the light organ. The use of pH-GFP expressing V. fischeri as a novel bioassay will allow us to determine whether pH is a determining factor in establishing a successful colonization by V. fischeri in sepiolid squids.
