The chordate ancestor possessed a single copy of the Brachyury gene for notochord acquisition.
The chordate ancestor possessed a single copy of the Brachyury gene for notochord acquisition.
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DOI：
10.1186/s40851-017-0064-9
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发表时间：
2017
影响因子：
2.7
通讯作者：
Satoh N
中科院分区：
文献类型：
--
作者：
Inoue J;Yasuoka Y;Takahashi H;Satoh N
T-box 家族转录因子基因 Brachyury 具有两个在动物胚胎发生过程中具有不同功能的表达域。与胚孔相关的初级结构域为大多数后生动物所共有，而涉及脊索的次级结构域是脊索动物所特有的。在大多数动物中，Brachyury 存在于单个拷贝中，但在头索动物（最基本的脊索动物）中，该基因存在于两个拷贝中，这表明每个重复项都分配有两个结构域。为了澄清 Brachyury 重复是否发生在脊索动物的共同祖先中，之后在尾索动物和脊椎动物谱系中丢失了一个重复，我们估计了 Brachyury 基因的系统发育关系，并检查了含有 Brachyury 的后口动物基因组区域与解码基因组的同线性。头索动物串联排列的 Brachyury 基因的单系起源表明，串联重复发生在头索动物谱系中，而不是在脊索动物祖先中。因此，我们的结果表明，在脊索动物的共同祖先中，Brachyury 的单个副本获得了两个表达域，并且该复制并不涉及脊索的获得。然而，就调节机制而言，在 Brachyury 的未来研究中应该考虑两种可能性，即具有两个域的单个副本和具有不同域的两个副本。本文的在线版本 (doi:10.1186/s40851-017-0064-9) 包含补充材料，可供授权用户使用。
The T-box family transcription-factor gene, Brachyury, has two expression domains with discrete functions during animal embryogenesis. The primary domain, associated with the blastopore, is shared by most metazoans, while the secondary domain, involved in the notochord, is specific to chordates. In most animals, Brachyury is present in a single copy, but in cephalochordates, the most basal of the chordates, the gene is present in two copies, suggesting allotment of the two domains to each of the duplicates. In order to clarify whether Brachyury duplication occurred in the common ancestor of chordates after which one of duplicates was lost in the urochordate and vertebrate lineages, we estimated phylogenetic relationships of Brachyury genes and examined the synteny of a Brachyury-containing genomic region of deuterostomes with decoded genomes. The monophyletic origin of tandemly arranged Brachyury genes of cephalochordates indicates that the tandem duplication occurred in the cephalochordate lineage, but not in the chordate ancestor. Our results thus suggest that, in the common ancestor of chordates, a single copy of Brachyury acquired two expression domains and that the duplication was not involved in the acquisition of the notochord. However, in relation to regulatory mechanisms, both possibilities—namely a single copy with two domains and two copies with different domains—should be considered in future studies of Brachyury. The online version of this article (doi:10.1186/s40851-017-0064-9) contains supplementary material, which is available to authorized users.