Molecular characterization of the gastrula in the turtle Emys orbicularis: an evolutionary perspective on gastrulation.
Molecular characterization of the gastrula in the turtle Emys orbicularis: an evolutionary perspective on gastrulation.
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DOI：
10.1371/journal.pone.0002676
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发表时间：
2008-07-16
期刊：
影响因子：
3.7
通讯作者：
Mazan S
中科院分区：
文献类型：
--
作者：
Coolen M;Nicolle D;Plouhinec JL;Gombault A;Sauka-Spengler T;Menuet A;Pieau C;Mazan S
由于在两栖动物中存在囊胚，海龟被认为是两栖动物向鸟类型原肠胚形成模式过渡的例证。为了验证这一假设，并深入了解羊膜在原肠胚形成过程中的独特特征，我们首次对爬行动物——环眼龟（Emys orbicularis）的原肠胚进行了分子表征。Brachyury, Lim1， Otx2和Otx5表达模式的研究表明羊膜模式生物的表达具有高度保守的动态，并使其能够确定中胚层内化的位置，这是爬行动物长期存在的问题。对Brachyury表达的分析也强调了两个不同阶段的存在，在模式生物中不太容易识别，分别以早期环状和后来的双边对称领土为特征。与四足动物模式生物的系统比较，使我们对所有爬行动物共有的囊胚孔/囊胚板系统、两栖动物的囊胚孔以及鸟类和哺乳动物的原始条纹之间的关系有了新的认识。双相Brachyury表达模式也与最近出现的双边对称模型一致，这就提出了其进化意义的问题。
Due to the presence of a blastopore as in amphibians, the turtle has been suggested to exemplify a transition form from an amphibian- to an avian-type gastrulation pattern. In order to test this hypothesis and gain insight into the emergence of the unique characteristics of amniotes during gastrulation, we have performed the first molecular characterization of the gastrula in a reptile, the turtle Emys orbicularis. The study of Brachyury, Lim1, Otx2 and Otx5 expression patterns points to a highly conserved dynamic of expression with amniote model organisms and makes it possible to identify the site of mesoderm internalization, which is a long-standing issue in reptiles. Analysis of Brachyury expression also highlights the presence of two distinct phases, less easily recognizable in model organisms and respectively characterized by an early ring-shaped and a later bilateral symmetrical territory. Systematic comparisons with tetrapod model organisms lead to new insights into the relationships of the blastopore/blastoporal plate system shared by all reptiles, with the blastopore of amphibians and the primitive streak of birds and mammals. The biphasic Brachyury expression pattern is also consistent with recent models of emergence of bilateral symmetry, which raises the question of its evolutionary significance.