Deuterostomic Development in the Protostome Priapulus caudatus
Deuterostomic Development in the Protostome Priapulus caudatus
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DOI：
10.1016/j.cub.2012.09.037
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发表时间：
2012-11
期刊：
影响因子：
9.2
通讯作者：
J. Martín-Durán;R. Janssen;Sofia A. Wennberg;G. Budd;A. Hejnol
中科院分区：
文献类型：
--
作者：
J. Martín-Durán;R. Janssen;Sofia A. Wennberg;G. Budd;A. Hejnol
在双边祖先的发育过程中，胚孔的命运目前还不清楚。在后口动物中，囊胚形成肛门，但其在原口动物群体中的命运是可变的。这种可变性，再加上缺少关键分类群的信息，阻碍了原口动物和两侧动物祖先发育模式的重建。双侧祖先的胚孔命运在理解从放射状到双侧对称生物的转变中起着至关重要的作用[2,3]。Priapulids形态保守，具有丰富的寒武纪化石记录，其系统发育地位使其成为了解原石动物进化的关键类群[4,5]。在这里，我们描述了尾状priapulus caudatus的原肠形成和参与双侧前肠和后肠模式的基因的胚胎表达。我们发现胚孔在植物极产生肛门，后肠标记物sbrachyury和尾侧在胚孔和肛门中表达，而前肠标记物sfoxay和尾侧在动物半球的口腔中表达。因此，原肠胚形成在保守进化的原胃中。尾状动物严格遵循后口动物模式。这些结果更符合后口发育模式，而不是原口发育模式（胚孔形成嘴）或两口发育模式（嘴和肛门同时形成）。
The fate of the blastopore during development in the bilaterian ancestor is currently not well understood. In deuterostomes, the blastopore forms the anus, but its fate in protostome groups is variable [1]. This variability, combined with an absence of information from key taxa, hampers the reconstruction of the ancestral developmental mode of the Protostomia and the Bilateria. The blastopore fate of the bilaterian ancestor plays a crucial role in understanding the transition from radial to bilateral symmetric organisms [2, 3]. Priapulids have a conservative morphology, an abundant Cambrian fossil record, and a phylogenetic position that make them a key group in understanding protostome evolution [4, 5]. Here, we characterize gastrulation and the embryonic expression of genes involved in bilaterian foregut and hindgut patterning inPriapulus caudatus. We show that the blastopore gives rise to the anus at the vegetal pole and that the hindgut markersbrachyuryandcaudalare expressed in the blastopore and anus, whereas the foregut markersfoxAandgoosecoidare expressed in the mouth in the animal hemisphere. Thereby, gastrulation in the conservatively evolving protostomeP. caudatusfollows strictly a deuterostomic pattern. These results are more compatible with a deuterostomic rather than protostomic (blastopore forms the mouth) or amphistomic (mouth and anus are formed simultaneously) mode of development in the last common bilaterian ancestor.