The evolutionary history of placodes:: a molecular genetic investigation of the larvacean urochordate Oikopleura dioica
The evolutionary history of placodes:: a molecular genetic investigation of the larvacean urochordate Oikopleura dioica
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DOI：
10.1242/dev.01973
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发表时间：
2005-10-01
期刊：
影响因子：
4.6
通讯作者：
Postlethwait, JH
中科院分区：
文献类型：
--
作者：
Bassham, S;Postlethwait, JH
脊椎动物基板的进化起源仍然是有争议的，因为不同的形态在尾索动物，头索动物和脊椎动物很难识别器官，显然是同源基板衍生的功能，包括嗅觉器官，腺垂体，透镜，内耳，侧线和颅神经节。尾索动物Oikopleura dioica的器官在形态上类似于脊椎动物的嗅觉器官和腺垂体。我们测试的假设，这些脊椎动物基板的直系同源物存在于一个larvacean urochordate通过分析的基板标记基因家族Eya，Pitx和六个的larvacean同源物的发育表达。我们的结论是，现存的脊索动物继承嗅觉和腺垂体基板从他们最后的共同祖先，但额外的独立增殖，也许失去基板类型可能发生在脊索动物的三个亚门。
The evolutionary origin of vertebrate placodes remains controversial because divergent morphologies in urochordates, cephalochordates and vertebrates make it difficult to recognize organs that are clearly homologous to placode-derived features, including the olfactory organ, adenohypophysis, lens, inner ear, lateral line and cranial ganglia. The larvacean urochordate Oikopleura dioica possesses organs that morphologically resemble the vertebrate olfactory organ and adenohypophysis. We tested the hypothesis that orthologs of these vertebrate placodes exist in a larvacean urochordate by analyzing the developmental expression of larvacean homologs of the placode-marking gene families Eya, Pitx and Six. We conclude that extant chordates inherited olfactory and adenohypophyseal placodes from their last common ancestor, but additional independent proliferation and perhaps loss of placode types probably occurred among the three subphyla of Chordata.