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.

Corals from the Persian/Arabian Gulf as models for thermotolerant reef-builders: Prevalence of clade C3 Symbiodinium, host fluorescence and ex situ temperature tolerance

“…These observations are in agreement with previous observations that also showed a loss of fluorescence under heat stress in other species (Desalvo et al, 2008;SmithKeune and Dove, 2007). Our results demonstrate clearly that FP fluorescence of P. lobata can be used for non-invasive optical monitoring of the stress response of the host tissue.…”

“…These host pigments belong to the family of GFP-like proteins (Alieva et al, 2008;Dove et al, 2001;Oswald et al, 2007;Wiedenmann et al, 2004Wiedenmann et al, , 2009) of which several (but not all) are regulated at transcriptional level in reef corals in response to changes in environmental conditions; in particular by blue light (Bay et al, 2009;D'Angelo et al, 2008;Desalvo et al, 2008;Leutenegger et al, 2007;Smith-Keune and Dove, 2007). Only recently, the expression of red FPs in the growth zones, wounded or epibiont-infested colony parts of P. lobata was correlated with areas characterised by accelerated cell proliferation .…”

Bacterial diversity and White Plague Disease-associated community changes in the Caribbean coral Montastraea faveolata

“…Future studies may also validate the application of PhyloChips as a versatile platform for monitoring and assessing reef water quality. This technology could also be coupled with other methods to assess the health state of corals including biochemical assays (Downs et al, 2005) or gene expression microarrays (Morgan et al, 2005;DeSalvo et al, 2008). The generation of such data sets could guide the implementation of these technologies in effective management strategies to preserve the most diverse marine ecosystem: coral reefs.…”

Investigating the Driving Mechanisms Behind Differences in Bleaching and Disease Susceptibility Between Two Scleractinian Corals, Pseudodiploria Strigosa and Diploria Labyrinthiformis

“…They have been found to be upregulated in Acropora millepora larvae subject to heat stress (Meyer et al 2011) and downregulated in heat stressed O. faveolata (DeSalvo et al 2008). In other studies, expression of ion transporters was found to be varied ).…”

“…Hypoxia response has also been observed to be upregulated in dark-induced bleached A. palmata (DeSalvo et al 2012), and oxidative stress genes are commonly upregulated in thermally stressed corals (DeSalvo et al 2008;Rodriguez-Lanetty et al 2009). It is particularly interesting in the present study that D. labyrinthiformis did not differentially express any of these stressrelated genes at any point.…”