Hemond Elizabeth M, Kaluziak Stefan T, Vollmer Steven V
Northeastern University, Marine Science Center, Nahant, MA, USA.
BMC Genomics. 2014 Dec 17;15:1133. doi: 10.1186/1471-2164-15-1133.
Colonial reef-building corals have evolved a broad spectrum of colony morphologies based on coordinated asexual reproduction of polyps on a secreted calcium carbonate skeleton. Though cnidarians have been shown to possess and use similar developmental genes to bilaterians during larval development and polyp formation, little is known about genetic regulation of colony morphology in hard corals. We used RNA-seq to evaluate transcriptomic differences between functionally distinct regions of the coral (apical branch tips and branch bases) in two species of Caribbean Acropora, the staghorn coral, A. cervicornis, and the elkhorn coral, A. palmata.
Transcriptome-wide gene profiles differed significantly between different parts of the coral colony as well as between species. Genes showing differential expression between branch tips and bases were involved in developmental signaling pathways, such as Wnt, Notch, and BMP, as well as pH regulation, ion transport, extracellular matrix production and other processes. Differences both within colonies and between species identify a relatively small number of genes that may contribute to the distinct "staghorn" versus "elkhorn" morphologies of these two sister species.
The large number of differentially expressed genes supports a strong division of labor between coral branch tips and branch bases. Genes involved in growth of mature Acropora colonies include the classical signaling pathways associated with development of cnidarian larvae and polyps as well as morphological determination in higher metazoans.
造礁珊瑚通过水螅体在分泌的碳酸钙骨骼上进行协调的无性繁殖，演化出了广泛的群体形态。尽管刺胞动物在幼虫发育和水螅体形成过程中已被证明拥有并使用与两侧对称动物相似的发育基因，但对于硬珊瑚群体形态的遗传调控却知之甚少。我们利用RNA测序技术评估了两种加勒比鹿角珊瑚（鹿角珊瑚，A. cervicornis，和麋角珊瑚，A. palmata）珊瑚功能不同区域（顶端分支尖端和分支基部）之间的转录组差异。
珊瑚群体不同部位以及不同物种之间的全转录组基因谱存在显著差异。在分支尖端和基部之间表现出差异表达的基因参与了发育信号通路，如Wnt、Notch和BMP，以及pH调节、离子运输、细胞外基质产生和其他过程。群体内部和物种之间的差异确定了相对少数可能导致这两个姊妹物种独特的“鹿角形”与“麋角形”形态的基因。
大量差异表达基因支持了珊瑚分支尖端和分支基部之间强大的分工。参与成熟鹿角珊瑚群体生长的基因包括与刺胞动物幼虫和水螅体发育以及高等后生动物形态决定相关的经典信号通路。
