Postdoctoral Fellowship: PRFB: Pre- and post-phagocytic winnowing mechanisms in cnidarian-algal endosymbiosis

This action funds an NSF Postdoctoral Research Fellowship in Biology for FY 2025. The fellowship supports research and training of the fellow that will contribute to biology in innovative ways. This project will study how cnidarians and algae form specific partnerships.

Many cnidarians form a symbiotic relationship with algae, which provide essential nutrients to the host. This partnership is critical for corals, the cnidarians which build coral reefs. Coral reefs are important for the environment and the economy, but the relationship between corals and algae is vulnerable to changes in the environment.

One way that corals can survive stressful conditions is by partnering with resistant algae. However, there are limits to which algae can associate with which corals. This research will study the chemical, molecular, and cellular processes that happen when these relationships form, which is important for understanding symbiosis and conserving corals.

The fellow will work with a team of scientists and teachers to accomplish research and educational goals. Additionally, the fellow will collaborate with artists to raise public awareness about coral reefs through a dance performance.

Partner specificity is often conferred by multi-step ‘winnowing’ mechanisms which select for compatible symbionts out of a diverse microbial pool. In cnidarian-algal symbioses, symbionts are initially taken up through phagocytosis, the same mechanism which initiates feeding and pathogen elimination. Whether these processes are differentiated from one another in cnidarians and distinct from symbiont uptake is unclear, and the mechanisms leading to specificity are unknown.

This project will use a comparative approach to uncover the mechanisms leading to specificity during two stages of symbiosis establishment, pre- and post-phagocytosis, by leveraging compatible and incompatible associations in the cnidarian model system, Exaiptasia diaphana. This research will first identify signaling molecules involved in partner recognition prior to uptake (pre-phagocytosis) by characterizing chemical exudates and their regulated pathways among incompatible and compatible associations using metabolomics and transcriptomics.

Candidate metabolites identified from these experiments will be functionally tested in an introductory-level Course-based Undergraduate Research Experience to advance research outcomes and increase undergraduate engagement. The mechanisms of symbiont sorting after uptake (post-phagocytosis), and the drivers of these response pathways, will also be characterized by quantifying gene expression, protein localization, and nutrient transfer when inoculated with compatible, incompatible, and heat-killed symbionts.

The fellow will gain training in chemical, cellular, and molecular techniques, as well as course development and scientific outreach, through interdisciplinary collaborations at the host institution.

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.