Dataset Information

Effects of temperature on gene expression in embryos of the coral Montastraea faveolata.

ABSTRACT:

Background

Coral reefs are expected to be severely impacted by rising seawater temperatures associated with climate change. This study used cDNA microarrays to investigate transcriptional effects of thermal stress in embryos of the coral Montastraea faveolata. Embryos were exposed to 27.5 degrees C, 29.0 degrees C, and 31.5 degrees C directly after fertilization. Differences in gene expression were measured after 12 and 48 hours.

Results

Analysis of differentially expressed genes indicated that increased temperatures may lead to oxidative stress, apoptosis, and a structural reconfiguration of the cytoskeletal network. Metabolic processes were downregulated, and the action of histones and zinc finger-containing proteins may have played a role in the long-term regulation upon heat stress.

Conclusions

Embryos responded differently depending on exposure time and temperature level. Embryos showed expression of stress-related genes already at a temperature of 29.0 degrees C, but seemed to be able to counteract the initial response over time. By contrast, embryos at 31.5 degrees C displayed continuous expression of stress genes. The genes that played a role in the response to elevated temperatures consisted of both highly conserved and coral-specific genes. These genes might serve as a basis for research into coral-specific adaptations to stress responses and global climate change.

SUBMITTER: Voolstra CR

PROVIDER: S-EPMC2807443 | biostudies-literature | 2009 Dec

REPOSITORIES: biostudies-literature

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Publications

Effects of temperature on gene expression in embryos of the coral Montastraea faveolata.

Voolstra Christian R CR Schnetzer Julia J Peshkin Leonid L Randall Carly J CJ Szmant Alina M AM Medina Mónica M

BMC genomics 20091223

<h4>Background</h4>Coral reefs are expected to be severely impacted by rising seawater temperatures associated with climate change. This study used cDNA microarrays to investigate transcriptional effects of thermal stress in embryos of the coral Montastraea faveolata. Embryos were exposed to 27.5 degrees C, 29.0 degrees C, and 31.5 degrees C directly after fertilization. Differences in gene expression were measured after 12 and 48 hours.<h4>Results</h4>Analysis of differentially expressed genes ...[more]

PMID: 20030803

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Project description:BACKGROUND:Scleractinian corals are the foundation of reef ecosystems in tropical marine environments. Their great success is due to interactions with endosymbiotic dinoflagellates (Symbiodinium spp.), with which they are obligately symbiotic. To develop a foundation for studying coral biology and coral symbiosis, we have constructed a set of cDNA libraries and generated and annotated ESTs from two species of corals, Acropora palmata and Montastraea faveolata. RESULTS:We generated 14,588 (Ap) and 3,854 (Mf) high quality ESTs from five life history/symbiosis stages (spawned eggs, early-stage planula larvae, late-stage planula larvae either infected with symbionts or uninfected, and adult coral). The ESTs assembled into a set of primarily stage-specific clusters, producing 4,980 (Ap), and 1,732 (Mf) unigenes. The egg stage library, relative to the other developmental stages, was enriched in genes functioning in cell division and proliferation, transcription, signal transduction, and regulation of protein function. Fifteen unigenes were identified as candidate symbiosis-related genes as they were expressed in all libraries constructed from the symbiotic stages and were absent from all of the non symbiotic stages. These include several DNA interacting proteins, and one highly expressed unigene (containing 17 cDNAs) with no significant protein-coding region. A significant number of unigenes (25) encode potential pattern recognition receptors (lectins, scavenger receptors, and others), as well as genes that may function in signaling pathways involved in innate immune responses (toll-like signaling, NFkB p105, and MAP kinases). Comparison between the A. palmata and an A. millepora EST dataset identified ferritin as a highly expressed gene in both datasets that appears to be undergoing adaptive evolution. Five unigenes appear to be restricted to the Scleractinia, as they had no homology to any sequences in the nr databases nor to the non-scleractinian cnidarians Nematostella vectensis and Hydra magnipapillata. CONCLUSION:Partial sequencing of 5 cDNA libraries each for A. palmata and M. faveolata has produced a rich set of candidate genes (4,980 genes from A. palmata, and 1,732 genes from M. faveolata) that we can use as a starting point for examining the life history and symbiosis of these two species, as well as to further expand the dataset of cnidarian genes for comparative genomics and evolutionary studies.

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. We employed a reference design where all control and dark-stressed samples were compared to a pooled reference aRNA sample composed of aRNA from all fragments. Since all RNA samples were compared to the reference sample, direct comparisons of gene expression across all time points and conditions can be performed.

Dataset Information

Effects of temperature on gene expression in embryos of the coral Montastraea faveolata.

Background

Results

Conclusions

Publications

Effects of temperature on gene expression in embryos of the coral Montastraea faveolata.

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