Meeting Abstract
Coral bleaching—the disruption of the symbiosis between a coral host and its endosymbiotic algae—is associated with environmental stressors. However, the molecular processes are not well understood, and no studies have disentangled the transcriptional bleaching response from the stress response. In order to characterize general stress response, specific stress responses, and the bleaching response, we isolated host and symbiont RNA from fragments of Acropora millepora which were exposed to 5 different stress treatments. We hypothesize that under stress conditions, the coral host, and not the symbionts, become stressed. If this hypothesis is correct we predict that the host may upregulate genes involved in oxidative stress, immune response, heat shock proteins, or lipid metabolism; we also expect that the symbiont would upregulate genes involved in growth and uptake of nutrients. Additionally, it is unknown whether the host or the symbiont initiates bleaching. Because symbionts are horizontally acquired, their success is not linked to the survival of the host. Thus, we hypothesize that when the host becomes stressed, the symbionts initiate bleaching. To capture the bleaching response, ambient conditions were reestablished after treatments and samples of RNA were taken at multiple time points, between 8-16 hours after the treatment. The RNA was sequenced with tag-based RNA sequencing and the data were analyzed using DESeq and WGCNA. If the symbionts initiate bleaching, we expect that the expression profile of the symbionts will resemble symbionts in the free-living state—such as upregulation of genes involved in sexual reproduction and motility. Conversely, if the host initiates bleaching we expect to upregulation of genes involved in immune response, exocytosis, or nutrient transport.
