Profiling Differential Gene Expression of Symbiotic and Aposymbiotic Corals Using a High Coverage Gene Expression Profiling (HiCEP) Analysis
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Coral generally harbors zooxanthellae (genus Symbiodinium) in the body for mutualistic symbiosis, which favors the host through effects on growth, stress response, and nutrient utilization. However, little is known about the molecular mechanisms by which the partners establish and regulate the endosymbiosis. In this study, we conducted a comprehensive transcriptome analysis in the coral Acropora tenuis using a high coverage gene expression profiling (HiCEP) method, to assess the genes that are involved in the coral–zooxanthellae symbiosis. For this purpose, we compared between aposymbiotic juveniles and those inoculated with a cultured monoclonal Symbiodinium species in two different clades (PL-TS-1 or CCMP2467). Among the 765 genes that exhibited different expression profiles between the two groups, 462 were upregulated and 303 downregulated by the symbiosis with somewhat variable responses to the two different symbionts. Among the responsive genes, we could annotate 33 genes by bioinformatic analyses and confirmed that their expression is actually altered in the same direction in the symbiotic individuals using real-time polymerase chain reaction. Functional analyses of the annotated genes indicate that they are involved in carbohydrate and lipid metabolism, intracellular signal transduction, and membrane transport of ions in the host corals as expected from the endosymbiosis of zooxanthellae.
KeywordsEndosymbiosis Reef-building coral Zooxanthellae Gene expression HiCEP
We are grateful to members of the Akajima Marine Science Laboratory, especially Mr. K. Iwao, for provision of Acropora tenuis larvae, to members of National Institute of Radiological Science for advice on the HiCEP method, and to Drs. Mutsumi Nishida, Susumu Hyodo, Makoto Kusakabe, and Jillian Healy of Ocean Research Institute, the University of Tokyo, for support and discussion. We also thank Dr. Michio Hidaka, Department of Biology, Chemistry and Marine Science, University of the Ryukyus, for encouragement. This work was supported in part by Grants-in-Aid (#16510157) to T. W., (#16207004) to Y. T., and (#19-10602) to I. Y. from the Japan Society for the Promotion of Science.
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