Collaborative Research: Cell biology of cnidarian-dinoflagellate symbiosis: Signaling, regulation and host response pathways

Coral reef ecosystems are biodiversity hotbeds that provide valuable environmental and economic services to half a billion people globally, including millions in the US. Reefs are faced with almost complete destruction by the end of the century due to global warming unless humanity can cap global temperature rise. Coral biologists are working together to develop a broad array of solutions to help with the coral reef crisis.

As a part of these efforts, discovery has a critical role to play. Corals are an intimate symbiosis between the coral animal and millions of single-celled algae that reside inside of coral cells. The algae provide photosynthetically derived sugars to the host in return for nutrients and a habitat.

Dysfunction of the symbiosis, caused by global warming and other human-caused impacts, is the driver of coral bleaching and is causing widespread reef degradation globally. This award will examine the cellular and molecular mechanisms governing the coral-algal partnership. The researchers will use state-of-the-art cellular and molecular tools to discover the chemical signals exchanged between the partners.

They will describe the role of the algae in early development of the host and explore the mechanisms of inter-partner regulation during healthy symbiosis and bleaching. The award includes extensive education and outreach aims. Undergraduate, graduate student and postdoctoral fellow training is central to the work.

Finally, the researchers will engage directly with the public, both in Oregon and Florida, through a variety of activities aimed at illustrating the importance of corals to science and society.

Many cnidarians, including corals and anemones, engage in a symbiosis with photosynthetic dinoflagellates (family Symbiodiniaceae) that together form the trophic and structural foundation of the coral reef ecosystem. Despite the importance of corals to coral reefs and the threatened state of coral reef health in an era of climate change, we have an incomplete understanding of how the partnerships are established, regulated and maintained.

The researchers will examine inter-partner signaling and regulation during onset, maintenance and breakdown of cnidarian-dinoflagellate symbioses. Experiments will be conducted largely in a laboratory-based sea anemone-Symbiodiniaceae model system. The team will carry out the following Specific Aims: Aim 1: Characterize algal-host signaling dynamics during onset, maintenance and breakdown of symbiosis by molecular glycan profiling of different symbiont species and by using a unbiased DNA aptamer technique to identify surface determinants of symbiotic algae.

Aim 2: Describe the spatio-temporal patterning of symbionts in hosts and their impact on host development and growth by examining the role of symbiosis on polyp development and exploring the dynamics of symbiont invasion in developing polyps. Aim 3: Examine the role of host response pathways in regulation of symbiosis by measuring changes in NADPH oxidase activity and sphingosine rheostat signaling in host tissues both during onset of symbiosis and in dysbiosis.

The researchers will develop a course-based undergraduate research experience (CURE) based on the sea anemone-Symbiodiniaceae model system and they will examine the effectiveness of the CURE in student learning and in building of science identity.

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.