title: Differential gene expression during thermal stress and bleaching in the Caribbean coral Montastraea faveolata.
abstract: 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, Ca(2+) 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 Ca(2+) homeostasis, which in turn leads to cytoskeletal and cell adhesion changes, decreased calcification, and the initiation of cell death via apoptosis and necrosis.
authors.affiliation: School of Natural Sciences, University of California, Merced, PO Box 2039, Merced, CA 95344, USA.
authors.forename: M K
authors.initials: MK
authors.lastname: DeSalvo
authors.forename: C R
authors.initials: CR
authors.lastname: Voolstra
authors.forename: S
authors.initials: S
authors.lastname: Sunagawa
authors.forename: J A
authors.initials: JA
authors.lastname: Schwarz
authors.forename: J H
authors.initials: JH
authors.lastname: Stillman
authors.forename: M A
authors.initials: MA
authors.lastname: Coffroth
authors.forename: A M
authors.initials: AM
authors.lastname: Szmant
authors.forename: M
authors.initials: M
authors.lastname: Medina
mesh_terms: D000818:Animals; D037421:Anthozoa / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D002113:Calcification, Physiologic; D002118:Calcium / Q000378:metabolism; D002448:Cell Adhesion; D016923:Cell Death; D000460:Chlorophyta / Q000235:genetics; D002980:Climate; D003599:Cytoskeleton / Q000378:metabolism; D018076:DNA, Complementary / Q000235:genetics; D017753:Ecosystem; D015870:Gene Expression; D020869:Gene Expression Profiling; D018869:Heat-Shock Response / Q000235:genetics*; D006358:Hot Temperature; D009569:Nitric Oxide / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D018384:Oxidative Stress; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013559:Symbiosis; D013997:Time Factors; D014158:Transcription, Genetic
chemical_list: D018076:DNA, Complementary; D012337:RNA, Ribosomal, 18S; D009569:Nitric Oxide; D002118:Calcium