Crinoids are considered as the most basal extant echinoderms. They retain aboral nervous system with a nerve center, which has been degraded in the eleutherozoan echinoderms. To investigate the evolution of patterning of the nervous systems in crinoids, we examined temporal and spatial expression patterns of three neural patterning-related homeobox genes, six3, pax6, and otx, throughout the development of a feather star Anneissia japonica. These genes were involved in the patterning of endomesodermal tissues instead of the ectodermal neural tissues in the early planktonic stages. In the stages after larval attachment, the expression of these genes was mainly observed in the podia and the oral nervous systems instead of the aboral nerve center. Our results indicate the involvement of these three genes in the formation of oral nervous system in the common ancestor of the echinoderms and suggest that the aboral nerve center is not evolutionally related to the brain of other bilaterians.

中文翻译：

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整个羽状星状Annenisia japonica早期和晚期发育过程中三个同源盒基因的基因表达分析。

海百合被认为是现存最基本的棘皮动物。它们保留着带有神经中枢的神经系统，该神经中枢在棘皮动物棘皮动物皮肤中已经退化。为了调查海百合类神经系统模式的演变，我们研究了整个羽状星安妮氏菌日本粳稻发育过程中三个与神经模式相关的同源盒基因six3，pax6和otx的时空表达模式。。在浮游早期，这些基因参与了内胚层组织而不是外胚层神经组织的模式。在幼虫附着后的阶段中，这些基因的表达主要在足部和口腔神经系统而不是在中枢神经中枢中观察到。我们的研究结果表明，这三个基因参与了棘皮动物共同祖先的口腔神经系统的形成，并表明，胎侧神经中枢与其他双​​语者的大脑没有进化关系。