Surprisingly complex T‐box gene complement in diploblastic metazoans
Surprisingly complex T‐box gene complement in diploblastic metazoans
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DOI：
10.1111/j.1525-142x.2007.00154.x
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发表时间：
2007-05
影响因子：
2.9
通讯作者：
A. Yamada;K. Pang;M. Martindale;S. Tochinai
中科院分区：
文献类型：
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作者：
A. Yamada;K. Pang;M. Martindale;S. Tochinai
摘要栉水母和刺胞动物是两个后生动物群，至少进化了600 Ma，早于寒武纪大爆发。虽然这两个群体通常被归类为双胚层动物没有衍生的中胚层，栉水母拥有明确的收缩“肌肉”细胞。T-box家族转录因子是一个进化上古老的基因家族，起源于后生动物的共同祖先，并已分为五个不同的亚科中的八个组，其中许多涉及中胚层以及外胚层和内胚层衍生结构的特化。在这里，我们报告的克隆和表达的五个T‐盒基因从栉水母，拟记忆。系统发育分析表明，栉水母至少拥有五个T-box亚家族中的三个成员，表达研究表明每个T-box基因在原肠胚形成和早期器官发生中的不同作用。此外，对海葵Nematostella vectensis（珊瑚虫刺胞动物）的基因组搜索显示，Nematostella中至少有13个T‐box基因，这些基因在栉水母中发现的三个亚科中至少分为六个不同的组。我们对两种双胚层动物的研究结果表明，真后生动物的共同祖先具有一组复杂的T盒基因，并且在三胚层进化过程中可能出现了两个不同的亚科。
SUMMARY Ctenophores and cnidarians are two metazoan groups that evolved at least 600 Ma, predating the Cambrian explosion. Although both groups are commonly categorized as diploblastic animals without derivatives of the mesodermal germ layer, ctenophores possess definitive contractile “muscle” cells. T‐box family transcription factors are an evolutionarily ancient gene family, arising in the common ancestor of metazoans, and have been divided into eight groups in five distinct subfamilies, many of which are involved in the specification of mesodermal as well as ectodermally and endodermally derived structures. Here, we report the cloning and expression of five T‐box genes from a ctenophore, Mnemiopsis leidyi. Phylogenetic analyses demonstrated that ctenophores possess members of at least three of the five T‐box subfamilies, and expression studies suggested distinct roles of each T‐box genes during gastrulation and early organogenesis. Moreover, genome searches of the sea anemone, Nematostella vectensis (anthozoan cnidarian), showed at least 13 T‐box genes in Nematostella, which are divided into at least six distinct groups in the same three subfamilies found in ctenophores. Our results from two diploblastic animals indicate that the common ancestor of eumetazoans had a complex set of T‐box genes and that two distinct subfamilies might have appeared during triploblastic evolution.