The Heath-Heckman
Symbiosis Lab
Michigan State University
© Alice Walker
Animals evolved in the presence of their microbial symbionts, most of which provide a benefit to their hosts. We in the Heath-Heckman lab at Michigan State University study the cellular, molecular, and genetic basis of bacterial-animal mutualisms with a focus on the host. To this end, we use the interaction between the Hawaiian bobtail squid (Euprymna scolopes) and its luminescent bacterial symbiont Vibrio fischeri to uncover the mechanisms by which animals select and maintain their bacterial symbionts.
© Bastien Quaak & Camille Boucaud
Upon hatching, juvenile squids are exposed to a complex microbial environment, in which V. fischeri typically represent less than 0.1% of the surrounding microbial population. Remarkably, molecular crosstalk between the squid and V. fischeri allows the squid to selectively recognize its sole bacterial partner. V. fischeri is then recruited into a specialized light organ, where the symbiosis is established. In return for nutrients and a protective environment, V. fischeri produces bioluminescence that matches downwelling moonlight, reducing the squid’s silhouette from upward-looking predators through a process known as counterillumination.