Differential gene expression during thermal stress and bleaching in the Caribbean coral Montastraea faveolata

• Published in: Molecular ecology 2008-09, Vol.17 (17), p.3952-3971
• Main Authors: DESALVO, M.K, VOOLSTRA, C.R, SUNAGAWA, S, SCHWARZ, J.A, STILLMAN, J.H, COFFROTH, M.A, SZMANT, A.M, MEDINA, M
• Format: Article
• Language: English
• Subjects: Animals; Anthozoa - genetics; Anthozoa - metabolism; Anthozoa - physiology; Biogeography; bleaching; Calcification, Physiologic; Calcium - metabolism; Cell Adhesion; Cell Death; Chlorophyta - genetics; Climate; coral; Coral reefs; corals; Cytoskeleton - metabolism; DNA, Complementary - genetics; Ecology; Ecosystem; Gene Expression; Gene Expression Profiling; Heat-Shock Response - genetics; Hot Temperature; Human influences; Marine; microarray; Molecular biology; Montastraea faveolata; Nitric Oxide - metabolism; Oligonucleotide Array Sequence Analysis; Oxidative Stress; Reverse Transcriptase Polymerase Chain Reaction; RNA, Ribosomal, 18S - genetics; Symbiosis; thermal stress; Time Factors; Transcription, Genetic
• ISSN: 0962-1083; 1365-294X
• DOI: 10.1111/j.1365-294X.2008.03879.x

The declining health of coral reefs worldwide is likely to intensify in response to continued anthropogenic disturbance from coastal development, pollution, and climate change. In response to these stresses, reef-building corals may exhibit bleaching, which marks the breakdown in symbiosis between coral and zooxanthellae. Mass coral bleaching due to elevated water temperature can devastate coral reefs on a large geographical scale. In order to understand the molecular and cellular basis of bleaching in corals, we have measured gene expression changes associated with thermal stress and bleaching using a complementary DNA microarray containing 1310 genes of the Caribbean coral Montastraea faveolata. In a first experiment, we identified differentially expressed genes by comparing experimentally bleached M. faveolata fragments to control non-heat-stressed fragments. In a second experiment, we identified differentially expressed genes during a time course experiment with four time points across 9 days. Results suggest that thermal stress and bleaching in M. faveolata affect the following processes: oxidative stress, Ca²⁺ homeostasis, cytoskeletal organization, cell death, calcification, metabolism, protein synthesis, heat shock protein activity, and transposon activity. These results represent the first medium-scale transcriptomic study focused on revealing the cellular foundation of thermal stress-induced coral bleaching. We postulate that oxidative stress in thermal-stressed corals causes a disruption of Ca²⁺ homeostasis, which in turn leads to cytoskeletal and cell adhesion changes, decreased calcification, and the initiation of cell death via apoptosis and necrosis.