Most, if not all, animals host beneficial microbes. When these associations are established, both partners undergo significant developmental changes as they accommodate to the symbiotic state. Microbial symbionts often induce alterations both in the host cells they directly contact, as well as in more remote cells and tissues. Often these changes involve toxic oxygen species such as nitric oxide (NO) that the host produces in response to bacteria. Similarly, motile bacteria often lose locomotory structures (flagella) upon host colonization. The squid Euprymna scolopes forms its light organ in response to colonization by the luminescent bacterium Vibrio fischeri. This project will focus on the roles of symbiont flagellation and host NO production. as both developmental phenotypes, and potential signaling molecules between the partners in this process. Two questions are addressed: 1) Does the environment of the developing light organ regulate synthesis of the flagellar apparatus? In turn, are flagellins, the principal proteins of the flagella, involved in the induction of the organ? 2) How do the bacteria reduce the host's defensive NO production and how does NO-binding by the symbionts give them a competitive advantage in the symbiosis? The proposed research will develop and apply a variety of techniques using molecular biology, molecular genetics and microscopy. This research promises to reveal some of the very basic "language" underlying the interactions of host cells with their bacterial partners. As all animals are now believed to have persistent interactions with essential microbes, the work should provide insight into very basic mechanisms of the biology of animals.
Broader Impacts: As researchers in the frontier field of beneficial animal-microbe interactions, the PIs view it as their responsibility to educate both the public and the community of biologists about this critical area of the biological world. To accomplish this goal, the PIs participate in educational-outreach efforts through U Wisconsin that facilitate training of students from high school through postdoctoral, as well as educating the public. These efforts include UW's Wisconsin Alliance for Minority Participation, a principal goal of which is to recruit underrepresented minorities into graduate labs at UW. In addition, the PIs' labs participate in the UW Outreach Club and PLATO (learning opportunities for seniors). The PI's and their labs disseminate information about the impact of symbiotic associations on animal biology both through interviews with the media and in the creation and maintenance of 5 public websites.
