Project description:This SuperSeries is composed of the following subset Series: GSE10630: Mfaveolata single-time point bleaching experiment GSE10632: Mfaveolata time course bleaching experiment Keywords: SuperSeries Refer to individual Series
Project description:Corals rely on a symbiosis with dinoflagellate algae (Symbiodinium spp.) to thrive in nutrient poor tropical oceans. However, the coral-algal symbiosis can break down during bleaching events, potentially leading to coral death. While genome-wide expression studies have shown the genes associated with the breakdown of this partnership, the full conglomerate of genes responsible for the establishment and maintenance of a healthy symbiosis remains unknown. Results from previous studies suggested little transcriptomic change associated with the establishment of symbiosis. In order to elucidate the transcriptomic response of the coral host in the presence of its associated symbiont, we utilized a comparative framework. Post-metamorphic aposymbiotic coral polyps of Orbicella faveolata were compared to symbiotic coral polyps 9 days after metamorphosis and the subsequent differential gene expression between control and treatment was quantified using cDNA microarray technology. Coral polyps exhibited differential expression of genes associated with nutrient metabolism and development, providing insight into pathways turned as a result of symbiosis driving early polyp growth. Furthermore, genes associated with lysosomal fusion were also upregulated, suggesting host regulation of symbiont densities soon after infection.
Project description:Coral bleaching occurs in response to numerous abiotic stressors, the ecologically most relevant of which is hyperthermic stress due to increasing seawater temperatures. Bleaching events can span large geographic areas and are currently a potent threat to coral reefs worldwide. Much effort has been focused on understanding the molecular and cellular events underlying bleaching, and these studies have mainly utilized heat and light stress regimes. In an effort to determine whether different stressors share common bleaching mechanisms, we used cDNA microarrays for the corals Acropora palmata and Montastraea faveolata (containing > 10,000 features) to measure differential gene expression during darkness stress. This is the first coral microarray experiment aimed at darkness stress, and the first for these species to interrogate gene expression at such a large scale. Our results reveal a striking transcriptomic response to darkness in A. palmata involving chaperone and antioxidant up-regulation, growth arrest, and metabolic modifications. As these responses were also measured during thermal stress, our results suggest that different stressors may share common bleaching mechanisms. Furthermore, our results point to ER stress as a critical cellular event involved in darkness-specific (and possibly more general) molecular bleaching mechanisms. On the other hand, we identified a meager transcriptomic response to darkness in M. faveolata where gene expression differences between host colonies and/or sampling locations were greater than differences between control and stressed fragments. To this end, we discuss the importance of factors related to host genotype, Symbiodinium genotype, and the abiotic environment that influence host gene expression and thereby can hinder an investigator’s ability to measure gene expression during a condition of interest.