Meeting Abstract
Increasing ocean temperatures resulting from climate change compromise the symbiotic relationship between coral hosts and their algal symbionts. Physiologically, coral hosts and their symbionts exhibit a wide array of stress responses; however, evidence suggests that host transcriptomes respond more strongly than the symbiont. This lack of transcriptional response by the alga raises the question: Are coral hosts regulating their symbiont’s environment to buffer environmental stress? We capitalize on the facultative symbiosis between two coral hosts (Oculina arbuscula and Astrangia poculata) and their algal symbionts (Breviolum psygmophilum) and characterize the transcriptomic responses of both partners to thermal extremes. We hypothesized that symbiotic hosts would mount stronger responses to thermal extremes than their algal partners (i.e. host buffering) and that the response of their aposymbiotic counterparts would be more subdued (hosts without symbionts are free from buffering this stress). To test this hypothesis, symbiotic and aposymbiotic fragments of each species were exposed to three treatments: 1) control (18°C), 2) heat stress (32°C), and 3) cold stress (6°C) and prepared for genome-wide gene expression profiling. Orthologous genes shared across the host and symbiont were identified and differential expression analyses were performed to compare the magnitude of response of symbiotic hosts, aposymbiotic hosts, and algal symbionts. Gene ontology enrichment analysis was also performed to elucidate the relative functional pathways involved in the stress responses of hosts and symbionts. While analyses are ongoing, testing this hypothesis will give rise to valuable insights about the molecular mechanisms underlying symbiosis maintenance in corals and the potential for host buffering in this symbiosis.
