PRFB FY 2021: Characterizing the symbiosome membrane in two divergent cnidarian lineages to investigate the cellular mechanisms and evolution of coral-algal symbiosis

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This action funds an NSF Postdoctoral Research Fellowship in Biology for FY 2022, Integrative Research Investigating the Rules of Life Governing Interactions Between Genomes, Environment and Phenotypes. The fellowship supports research and training of the fellow that will contribute to the area of Rules of Life in innovative ways. The fellow will use cutting-edge gene-editing and molecular techniques to study the fundamental mechanisms governing the symbiosis between corals and algae that live with the coral, which is a key aspect of coral health. Climate change threatens the stability of this symbiosis and therefore can impact coral survival. Better understanding this relationship therefore may help with the development of solutions for coral survival. The fellow will support diversity and inclusion in the sciences by presenting their work at outreach events in Baltimore, MD, developing a hands-on curriculum for local K-12 students using a sea anemone, and by designing a research-based course for Oregon State University’s Invertebrate Biology lab.In cnidarian-algal photosymbiosis, the algal symbiont resides within a phagosomal membrane, called the symbiosome. Proteins localize to the symbiosome membrane to maintain symbiosis, and several of these proteins are shared among hosts that evolved photosymbiosis independently. The fellow will characterize the symbiosome membrane proteome in two divergent cnidarian lineages that have independently gained photosymbiosis: the sea anemone Exaiptasia diaphana and the coral Acropora millepora. To characterize the symbiosome membrane proteome, first, algal cells will be isolated from each host species and symbiosome-positive algal cells will be enriched with antibody labeling and flow cytometry. Then, symbiosome membrane proteins will be purified with biochemistry and identified using tandem mass spectrometry. The fellow will then test the function of symbiosome membrane proteins by knocking out each gene with CRISPR/Cas9 in the two host species. Knockout larvae will be inoculated with algal symbionts and symbiont density will be measured. Knockouts of genes critical for symbiosis are predicted to have a strong effect on symbiont density, while those that are less vital will have weaker effects. Finally, the fellow will develop a course-based undergraduate research experience at Oregon State University where students will characterize the gene expression of symbiosome membrane proteins in E. diaphana larvae through a time course during the early stages of symbiosis. Expression of these genes are expected to vary temporally depending on their function. The fellow will be trained by his sponsors in bioinformatics, proteomics, CRISPR/cas9 knockout techniques, and curriculum development.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.