Takada Norio, Goto Taichiro, Satoh Nori
Genesis. 2002 Mar;32(3):240-5. doi: 10.1002/gene.10077.
Arrow worms (the phylum Chaetognatha), which are among the major marine planktonic animals, are direct developers and exhibit features characteristic of both deuterostomes and protostomes. In particular, the embryonic development of arrow worms appears to be of the deuterostome type. Brachyury functions critically in the formation of the notochord in chordates, whereas the gene is expressed in both the blastopore and stomodeum invagination regions in embryos of hemichordates and echinoderms. Here we analyzed the expression of Brachyury (Pg-Bra) in the arrow worm Paraspadella gotoi and showed that Pg-Bra is expressed in the blastopore region and the stomodeum region in the embryo and then around the mouth opening region at the time of hatching. The expression of Pg-Bra in the embryo resembles that of Brachyury in embryos of hemichordates and echinoderms, whereas that in the mouth opening region in the hatchling appears to be novel.
箭虫（毛颚动物门）是主要的海洋浮游动物之一，属于直接发育型，具有后口动物和原口动物的特征。特别是，箭虫的胚胎发育似乎属于后口动物类型。短尾相关蛋白在脊索动物脊索的形成中起关键作用，而该基因在半索动物和棘皮动物胚胎的胚孔和口凹内陷区域均有表达。在这里，我们分析了短尾相关蛋白（Pg-Bra）在戈氏副叶颚虫中的表达，结果表明Pg-Bra在胚胎的胚孔区域和口凹区域表达，然后在孵化时围绕开口区域表达。胚胎中Pg-Bra的表达类似于半索动物和棘皮动物胚胎中短尾相关蛋白的表达，而幼体开口区域的表达似乎是新发现的。
