Research overview
Microbes shape animal physiology, evolution, and can cause or protect against disease. Extensive studies on animal-pathogen relationships have enhanced our understanding of immunity, cell biology, and disease therapies. In recent years, the importance of beneficial microbes in animal health has become clear. However, the complexity of microbes associated with animals has made it difficult to both identify beneficial microbes and to discover the cell biology underlying their benefit, severely limiting progress in the field. These knowledge gaps can be addressed by using simple, genetically tractable animal models with well-defined symbionts.
Over the past four years, my lab has developed genetic tools in the small anemone, Aiptasia, that has an intracellular endosymbiotic relationship with dinoflagellate algae. These dinoflagellate algal symbionts are re-established in each generation and reside inside the gastrodermal cells of the animal in a novel phagolysosome-like organelle. Aiptasia is a powerful model for beneficial microbial relationships relevant to biomedicine for several reasons. First, the structure and content of sea anemone genomes are more conserved to humans than in other models (e.g., insects and nematodes), enabling the study of conserved pathways of host-microbe interactions. Second, the dinoflagellate symbionts are closely related to well-studied
apicomplexan parasites (e.g., Plasmodium falciparum), allowing for
comparisons of the mechanisms used by intracellular pathogens and beneficial microbes to modulate animal cell biology. These new genetic tools in an experimentally tractable symbiotic animal offer a powerful untapped opportunity to dissect the mechanisms of beneficial animal-microbe interactions.​
Finally, this symbiosis is critical for the survival of coral reefs, and its breakdown (or "coral bleaching”) due to anthropogenic stressors, including climate change, is leading to the global decline of coral ecosystems. The loss of these
biodiversity hotspots is causing extensive economic and human health damage. By studying this symbiosis, we can gain key molecular insights into how corals will fare during increased climate change and the development of new conservation strategies.
Research Themes
What are the genetic and molecular pathways to establish and maintain symbiosis?
Using a combination of ‘omics approaches, we have identified a set of genes and pathways potentially involved in the early steps of symbiosis formation and the maintenance of symbiosis. We are applying our novel genetic techniques to characterize the gene regulatory networks required for symbiosis.
What genes and cellular mechanisms drive the breakdown of symbiosis due to stress?
Despite hundreds of studies, we still do not understand the mechanisms that trigger and/or protect against bleaching. Several models have been proposed, but most have not been tested adequately. We are using a combination of genetic and cellular studies in Aiptasia and coral to investigate these mechanisms.
What underlies natural variation and evolution in the bleaching response?
Corals and anemones vary naturally in their tolerance to the stresses that cause bleaching. Major genetic contributors to this variation are both the cnidarians’ own genotypes and those of their algal symbionts. We are using model systems to discover how algal symbionts impact the ability of the host to tolerate stress.
Expand the genetic and molecular tool-kit for symbiotic cnidarians.
We are continuing to expand the number of state-of-the-art molecular techniques available in symbiotic cnidarians. These new tools will continue to facilitate the discovery of basic principles of symbiosis and animal-microbe interactions, broadly.
