Warm seawater temperature promotes substrate colonization by the blue coral, Heliopora coerulea
Warm seawater temperature promotes substrate colonization by the blue coral, Heliopora coerulea
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DOI：
10.7717/peerj.7785
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发表时间：
2019-09-27
期刊：
影响因子：
2.7
通讯作者：
Conaco, Cecilia
中科院分区：
文献类型：
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作者：
Guzman, Christine;Atrigenio, Michael;Conaco, Cecilia
背景资料：蓝珊瑚（Heliopora coerulea）是一种造礁珊瑚，据报道，与大多数石珊瑚相比，它具有更高的最适生长温度。据观察，这种珊瑚生长在活的和死的硬珊瑚上，并在印度太平洋地区的某些珊瑚礁中占主导地位。H. coerulea的耐受更温暖的海水温度和有效地竞争空间的基板上仍然有待阐明。coerulea殖民地的各种温度长达3周。测量珊瑚群体的生长和光合效率。然后，我们对不同珊瑚组织区域之间的基因表达进行了成对比较，以确定在不同温度条件下表达的基因和途径。结果：观察到珊瑚在28或31摄氏度下每周的水平生长率为1.13 +/- 0.25毫米。与暴露在26摄氏度下的珊瑚相比，这一增长率明显更高。这种新生长的特征是在殖民地边缘延伸出白色组织，并富含基质金属肽酶、钙和整联蛋白结合蛋白以及其他功能未知的转录物。组织在生长边缘和邻近的钙化结壳区域丰富的成绩单相关的脯氨酸和核黄素代谢，氮的利用，和有机阳离子运输。另一方面，钙化的指状区富含编码参与细胞-基质粘附、翻译、受体介导的内吞作用、光合作用和离子转运的蛋白质的转录物。与脂质生物合成，细胞外基质形成，细胞迁移和氧化还原过程相关的功能在珊瑚的生长边缘富集，相对于26摄氏度的珊瑚，珊瑚在28或31摄氏度下生长3周。在珊瑚的指状突区域，与28摄氏度的珊瑚相比，在暴露于31摄氏度仅24小时后，编码保护免受氧化应激，改变细胞膜组成和介导细胞间信号传导途径的蛋白质的转录物就富集了。在持续暴露于31摄氏度3周后观察到的基因表达的整体下调可能被共生体代谢所补偿。蓝斑具有可变的基因表达谱和对温度变化的响应。在温暖的条件下，蓝珊瑚投资细胞资源对细胞外基质的形成和细胞迁移的殖民地的边缘，这可能会促进快速组织生长和扩展。这种机制使珊瑚能够在邻近的珊瑚礁基质中定居，并成功地使生长较慢的石珊瑚过度生长，这些石珊瑚可能已经更容易受到海洋沃茨变暖的影响。
Background: Heliopora coerulea, the blue coral, is a reef building octocoral that is reported to have a higher optimum temperature for growth compared to most scleractinian corals. This octocoral has been observed to grow over both live and dead scleractinians and to dominate certain reefs in the Indo-Pacific region. The molecular mechanisms underlying the ability of H. coerulea to tolerate warmer seawater temperatures and to effectively compete for space on the substrate remain to be elucidated.Methods: In this study, we subjected H. coerulea colonies to various temperatures for up to 3 weeks. The growth and photosynthetic efficiency rates of the coral colonies were measured. We then conducted pairwise comparisons of gene expression among the different coral tissue regions to identify genes and pathways that are expressed under different temperature conditions.Results: A horizontal growth rate of 1.13 +/- 0.25 mm per week was observed for corals subjected to 28 or 31 degrees C. This growth rate was significantly higher compared to corals exposed at 26 degrees C. This new growth was characterized by the extension of whitish tissue at the edges of the colony and was enriched for a matrix metallopeptidase, a calcium and integrin binding protein, and other transcripts with unknown function. Tissues at the growth margin and the adjacent calcified encrusting region were enriched for transcripts related to proline and riboflavin metabolism, nitrogen utilization, and organic cation transport. The calcified digitate regions, on the other hand, were enriched for transcripts encoding proteins involved in cell-matrix adhesion, translation, receptor-mediated endocytosis, photosynthesis, and ion transport. Functions related to lipid biosynthesis, extracellular matrix formation, cell migration, and oxidation-reduction processes were enriched at the growth margin in corals subjected for 3 weeks to 28 or 31 degrees C relative to corals at 26 degrees C. In the digitate region of the coral, transcripts encoding proteins that protect against oxidative stress, modify cell membrane composition, and mediate intercellular signaling pathways were enriched after just 24 h of exposure to 31 degrees C compared to corals at 28 degrees C. The overall downregulation of gene expression observed after 3 weeks of sustained exposure to 31 degrees C is likely compensated by symbiont metabolism.Discussion: These findings reveal that the different regions of H. coerulea have variable gene expression profiles and responses to temperature variation. Under warmer conditions, the blue coral invests cellular resources toward extracellular matrix formation and cellular migration at the colony margins, which may promote rapid tissue growth and extension. This mechanism enables the coral to colonize adjacent reef substrates and successfully overgrow slower growing scleractinian corals that may already be more vulnerable to warming ocean waters.