Integrative Biology Section, The University of Texas at Austin, Austin, TX 78712, USA.
Mol Ecol. 2011 Sep;20(17):3599-616. doi: 10.1111/j.1365-294X.2011.05205.x. Epub 2011 Jul 29.
Elevated temperatures resulting from climate change pose a clear threat to reef-building corals; however, the traits that might influence corals' survival and dispersal during climate change remain poorly understood. Global gene expression profiling is a powerful hypothesis-forming tool that can help elucidate these traits. Here, we applied a novel RNA-Seq protocol to study molecular responses to heat and settlement inducers in aposymbiotic larvae of the reef-building coral Acropora millepora. This analysis of a single full-sibling family revealed contrasting responses between short- (4-h) and long-term (5-day) exposures to elevated temperatures. Heat shock proteins were up-regulated only in the short-term treatment, while the long-term treatment induced the down-regulation of ribosomal proteins and up-regulation of genes associated with ion transport and metabolism (Ca(2+) and CO(3)(2-)). We also profiled responses to settlement cues using a natural cue (crustose coralline algae, CCA) and a synthetic neuropeptide (GLW-amide). Both cues resulted in metamorphosis, accompanied by differential expression of genes with known developmental roles. Some genes were regulated only by the natural cue, which may correspond to the recruitment-associated behaviour and morphology changes that precede metamorphosis under CCA treatment, but are bypassed under GLW-amide treatment. Validation of these expression profiles using qPCR confirmed the quantitative accuracy of our RNA-Seq approach. Importantly, qPCR analysis of different larval families revealed extensive variation in these responses depending on genetic background, including qualitative differences (i.e. up-regulation in one family and down-regulation in another). Future studies of gene expression in corals will have to address this genetic variation, which could have important adaptive consequences for corals during global climate change.
气候变化导致的温度升高对造礁珊瑚构成了明显威胁；然而，影响珊瑚在气候变化过程中生存和扩散的特征仍知之甚少。全局基因表达谱分析是一种强大的假设形成工具，可以帮助阐明这些特征。在这里，我们应用一种新的 RNA-Seq 方案来研究无共生幼虫对热和定居诱导物的分子反应，这些幼虫来自造礁珊瑚 Acropora millepora。对一个单一家系的分析显示，短期（4 小时）和长期（5 天）暴露于高温下的反应截然不同。热休克蛋白仅在短期处理中上调，而长期处理则诱导核糖体蛋白下调和与离子转运和代谢（Ca(2+) 和 CO(3)(2-)）相关的基因上调。我们还使用天然诱导物（结皮层珊瑚藻，CCA）和合成神经肽（GLW-酰胺）来分析对定居诱导物的反应。这两种诱导物都导致了变态，伴随着已知发育作用的基因的差异表达。一些基因仅受天然诱导物调节，这可能对应于在 CCA 处理下，先于变态的与招募相关的行为和形态变化，但在 GLW-酰胺处理下被绕过。使用 qPCR 对这些表达谱进行验证，证实了我们的 RNA-Seq 方法的定量准确性。重要的是，对不同幼虫家系的 qPCR 分析显示，这些反应存在广泛的遗传背景差异，包括定性差异（即一个家系上调，另一个家系下调）。未来对珊瑚基因表达的研究必须解决这种遗传变异，这可能对珊瑚在全球气候变化过程中具有重要的适应性影响。
