Intellectual Merit: Annelid tubeworms belonging to the group Siboglinidae are one of the most successful and diverse animal lineages with obligate symbioses. As adults, these worms lack a functional gut, mouth and anus, and derive energy from bacteria housed within a unique storage organ. Some species within this worm group are well studied due to their dominance at hydrothermal vents and hydrocarbon seeps, whereas other species are poorly known despite a broad distribution in the deep sea. To understand establishment, maintenance, and diversification of these bacterial symbiotic relationships, the investigators will explore the diversity of symbioses within tubeworms and examine molecular processes and mechanisms in host tissue and bacteria in contrasting metabolic pathways that use hydrogen sulfide or methane as a primary energy source. Using candidate species and a range of life-history stages, expressed genes of hosts and symbionts will be surveyed using next-generation pyrosequencing and microarray-based technologies. A goal of the project is to identify important, broad-scale molecular processes directly associated with these symbioses. A bioinformatic, systems-level approach will enable analysis, comparison, and generalization to other terrestrial and aquatic symbiotic systems. Broader Impacts: All organisms, including humans, are associated with microbial flora. This work will be integral to elucidating how microbial associations have shaped animal biology and evolution. It will also interest those studying invertebrate evolution and diversity, microbial processes and annelids, as well as the symbiosis scientific community. A web-based portal, accessible to K-12 students and researchers, will be developed. This project includes three beginning investigators, a graduate student and a technician. All investigators actively teach and mentor students, seek out personnel from underrepresented groups, and engage in formal outreach efforts. Results obtained from this project will be presented at international meetings and published in peer-reviewed journals. Molecular and computational resources for the study of symbioses will be made publicly available.
