Shoguchi E, Satoh N, Maruyama Y K
Department of Zoology, Graduate School of Science, Kyoto University, Sakyo-Ku, Kyoto 606-8502, Japan.
Mech Dev. 1999 Apr;82(1-2):185-9. doi: 10.1016/s0925-4773(99)00008-8.
Echinoderms, hemichordates and chordates are deuterostomes and share a number of developmental features. The Brachyury gene is responsible for formation of the notochord, the most defining feature of chordates, and thus may be a key to understanding the origin and evolution of the chordates. Previous studies have shown that the ascidian Brachyury (As-T and Ci-Bra) is expressed in the notochord and that a sea urchin Brachyury (HpTa) is expressed in the secondary mesenchyme founder cells. A recent study by [Tagawa et al. (1998)], however, revealed that a hemichordate Brachyury (PfBra) is expressed in a novel pattern in an archenteron invagination region and a stomodaeum invagination region in the gastrula. The present study demonstrated that the expression pattern of Brachyury (ApBra) of starfish embryos resembles that of PfBra in hemichordate embryos but not of HpTa in sea urchin embryos. Namely, ApBra is expressed in an archenteron invagination region and a stomodaeum invagination region.
棘皮动物、半索动物和脊索动物都是后口动物，具有许多发育特征。短尾基因负责脊索的形成，而脊索是脊索动物最具决定性的特征，因此可能是理解脊索动物起源和进化的关键。先前的研究表明，海鞘短尾基因（As-T和Ci-Bra）在脊索中表达，海胆短尾基因（HpTa）在次生间充质起始细胞中表达。然而，[田川等人（1998年）]最近的一项研究表明，半索动物短尾基因（PfBra）在原肠胚的原肠内陷区域和口凹内陷区域以一种新的模式表达。本研究表明，海星胚胎的短尾基因（ApBra）的表达模式类似于半索动物胚胎中的PfBra，而不像海胆胚胎中的HpTa。也就是说，ApBra在原肠内陷区域和口凹内陷区域表达。
