Coral Genomics Group, James Cook University, Townsville, QLD 4811, Australia.
Mar Biotechnol (NY). 2010 Oct;12(5):594-604. doi: 10.1007/s10126-009-9247-5. Epub 2009 Dec 30.
Coral bleaching is a major threat to coral reefs worldwide and is predicted to intensify with increasing global temperature. This study represents the first investigation of gene expression in an Indo-Pacific coral species undergoing natural bleaching which involved the loss of algal symbionts. Quantitative real-time polymerase chain reaction experiments were conducted to select and evaluate coral internal control genes (ICGs), and to investigate selected coral genes of interest (GOIs) for changes in gene expression in nine colonies of the scleractinian coral Acropora millepora undergoing bleaching at Magnetic Island, Great Barrier Reef, Australia. Among the six ICGs tested, glyceraldehyde 3-phosphate dehydrogenase and the ribosomal protein genes S7 and L9 exhibited the most constant expression levels between samples from healthy-looking colonies and samples from the same colonies when severely bleached a year later. These ICGs were therefore utilised for normalisation of expression data for seven selected GOIs. Of the seven GOIs, homologues of catalase, C-type lectin and chromoprotein genes were significantly up-regulated as a result of bleaching by factors of 1.81, 1.46 and 1.61 (linear mixed models analysis of variance, P < 0.05), respectively. We present these genes as potential coral bleaching response genes. In contrast, three genes, including one putative ICG, showed highly variable levels of expression between coral colonies. Potential variation in microhabitat, gene function unrelated to the stress response and individualised stress responses may influence such differences between colonies and need to be better understood when designing and interpreting future studies of gene expression in natural coral populations.
珊瑚白化是全球珊瑚礁的主要威胁，预计随着全球温度的升高，这种威胁将加剧。本研究代表了对经历自然白化（即失去藻类共生体）的印度洋-太平洋珊瑚物种的基因表达进行的首次调查。定量实时聚合酶链反应实验用于选择和评估珊瑚内参基因（ICGs），并研究 9 个大堡礁磁性岛白化珊瑚（石珊瑚纲珊瑚属 Acropora millepora）中感兴趣的珊瑚基因（GOIs）的表达变化。在测试的 6 个 ICG 中，甘油醛 3-磷酸脱氢酶和核糖体蛋白基因 S7 和 L9 在来自外观健康的珊瑚样本和一年后严重白化的同一珊瑚样本之间表现出最稳定的表达水平。因此，这些 ICG 被用于对 7 个选定 GOIs 的表达数据进行归一化。在 7 个 GOIs 中，过氧化氢酶、C 型凝集素和色蛋白基因的同源物因白化而分别上调了 1.81、1.46 和 1.61 倍（线性混合模型方差分析，P < 0.05）。我们将这些基因作为潜在的珊瑚白化反应基因提出。相比之下，三个基因，包括一个假定的 ICG，在珊瑚礁之间表现出高度可变的表达水平。微生境的潜在差异、与应激反应无关的基因功能和个体应激反应可能会影响这些差异，因此在设计和解释未来对自然珊瑚种群基因表达的研究时需要更好地理解。
