Identification of an intact ParaHox cluster with temporal colinearity but altered spatial colinearity in the hemichordate Ptychodera flava.
Identification of an intact ParaHox cluster with temporal colinearity but altered spatial colinearity in the hemichordate Ptychodera flava.
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DOI：
10.1186/1471-2148-13-129
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发表时间：
2013-06-27
影响因子：
3.4
通讯作者：
Su YH
中科院分区：
文献类型：
--
作者：
Ikuta T;Chen YC;Annunziata R;Ting HC;Tung CH;Koyanagi R;Tagawa K;Humphreys T;Fujiyama A;Saiga H;Satoh N;Yu JK;Arnone MI;Su YH
ParaHox和Hox基因被认为是从一个共同的祖先ProtoHox集群进化而来的，或者是在刺胞动物和两侧刺胞动物分化之前从串联重复进化而来的。与Hox簇类似，脊索动物ParaHox基因包括Gsx、Xlox和Cdx，是簇状的，并且它们的表达表现出时间和空间共线性。然而，在非脊索动物中，关于ParaHox基因的基因组组织的研究仅限于少数动物类群。半脊索动物，如Enteropneust橡子蠕虫，已被用于深入了解脊索动物特征的起源。在这项研究中，我们调查的基因组组织和ParaHox基因的表达在间接发展的半索动物橡子蠕虫Ptychodera黄。我们发现，P. flava包含一个完整的ParaHox簇，其排列与脊索动物相似。黄球藻ParaHox基因的时间表达顺序与脊索动物ParaHox基因的时间表达顺序相同。在胚胎发生过程中，PfCdx在后内胚层的空间表达模式代表了与其在其他动物中的直系同源物的表达相似的保守特征。另一方面，PfXlox和PfGsx在囊胚孔中表现出新颖的表达模式。然而，在变态期间，PfXlox和PfCdx在内胚层中以类似于脊索动物中的情况的空间交错模式表达。我们的研究表明，尽管形成了一个完整的簇，但在胚胎发生过程中，黄曲霉ParaHox基因表现出时间共线性，但失去了空间共线性。在变态过程中，部分空间共线性保留在转化幼虫。这些结果强烈表明，完整的ParaHox基因聚类保留在后口类祖先，并与时间共线性。
ParaHox and Hox genes are thought to have evolved from a common ancestral ProtoHox cluster or from tandem duplication prior to the divergence of cnidarians and bilaterians. Similar to Hox clusters, chordate ParaHox genes including Gsx, Xlox, and Cdx, are clustered and their expression exhibits temporal and spatial colinearity. In non-chordate animals, however, studies on the genomic organization of ParaHox genes are limited to only a few animal taxa. Hemichordates, such as the Enteropneust acorn worms, have been used to gain insights into the origins of chordate characters. In this study, we investigated the genomic organization and expression of ParaHox genes in the indirect developing hemichordate acorn worm Ptychodera flava. We found that P. flava contains an intact ParaHox cluster with a similar arrangement to that of chordates. The temporal expression order of the P. flava ParaHox genes is the same as that of the chordate ParaHox genes. During embryogenesis, the spatial expression pattern of PfCdx in the posterior endoderm represents a conserved feature similar to the expression of its orthologs in other animals. On the other hand, PfXlox and PfGsx show a novel expression pattern in the blastopore. Nevertheless, during metamorphosis, PfXlox and PfCdx are expressed in the endoderm in a spatially staggered pattern similar to the situation in chordates. Our study shows that P. flava ParaHox genes, despite forming an intact cluster, exhibit temporal colinearity but lose spatial colinearity during embryogenesis. During metamorphosis, partial spatial colinearity is retained in the transforming larva. These results strongly suggest that intact ParaHox gene clustering was retained in the deuterostome ancestor and is correlated with temporal colinearity.
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Annunziata R;Martinez P;Arnone MI
通讯作者：
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