The Cellular and Genetic Mechanisms of Stress Response Pathways in Caribbean Coral
Abstract
Reef-building corals are in decline around the globe due to both the effects of increased ocean temperatures and the emergence of marine diseases which affect corals. These emerging issues threaten the continued persistence of reefs and the ecosystem which they form as the mechanisms which corals use to respond to stress remain poorly characterized, limiting the success of interventions aimed at reversing these declines. To address these issues my dissertation focused on uncovering the cellular and genetic mechanism utilized by Caribbean corals during periods of stress. Towards this aim my second chapter identified and characterized a mitochondrial stress response pathway in the coral Orbicella faveolata and demonstrated that this pathway is activating during both exposure to increased temperature as well as immune stimulation by regulating the expression of numerous stress response genes. In chapter three I use the model system Cassiopea xamachana to show that the breakdown of symbiosis during temperature stress is associated with declining mitochondrial function which is reflected at the transcriptional level. In chapter four I utilize comparative genomic data to characterize the expansion and domain shuffling of a key class of immune genes known as NOD-like receptors and demonstrate that these genes are responsive to both increased temperature and immune stimulation in O. faveolata. Finally, in chapter five I expanded upon these results to show that immune related genes demonstrate substantial variation in copy number across five ecologically important species leading to divergent expression of these immune genes. Overall, these research chapters advance the understanding of both the cellular and genetic mechanism utilized by Caribbean corals in response to stressful environmental conditions.