tbx6, a Brachyury-related gene expressed by ventral mesendodermal precursors in the zebrafish embryo
tbx6, a Brachyury-related gene expressed by ventral mesendodermal precursors in the zebrafish embryo
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DOI：
10.1006/dbio.1996.8490
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发表时间：
1997-03-01
影响因子：
2.7
通讯作者：
Grunwald, DJ
中科院分区：
文献类型：
--
作者：
Hug, B;Walter, V;Grunwald, DJ
经典胚胎学实验表明存在背侧型和腹侧型中胚层，它们是脊椎动物发育过程中中胚层诱导的结果。在这里，我们报道斑马鱼 tbx6 基因是 Brachyury 相关 T 盒基因家族的成员，仅由腹侧中内胚层表达。三个观察结果将 tbx6 的表达与腹侧中胚层规范联系起来。首先，该基因最初在原肠胚形成开始时在表达泛中胚层基因、无尾（Brachyury）的腹外侧细胞亚群内表达。其次，中胚层诱导因子激活素和 bFGF 激活动物帽中 tbx6 的表达。第三，胚胎暴露于锂离子后中内胚层前体群体的背侧化导致 tbx6 转录下调。 tbx6 在腹侧中内胚层的退化衍生物中短暂表达，产生非轴中胚层组织；随着组织分化的进展，其表达消失。 tbx6 的转录在泛中内胚层基因 no tail 和组织者基因 goosecoid 开始表达后约一小时开始。在无尾突变体胚胎中检查了 tbx6 表达对无尾活性的依赖性。腹侧中胚层中 tbx6 转录的激活不依赖于无尾基因活性。然而，失败似乎有助于维持 tbx6 转录的正常水平，并且可能是发育尾部中 tbx6 转录所必需的。 (C) 1997 年学术出版社。
Classical embryology experiments have indicated the existence of dorsal-type and ventral-type mesoderms that arise as a consequence of mesoderm induction during vertebrate development. Here we report that the zebrafish tbx6 gene, a member of the Brachyury-related T-box family of genes, is exclusively expressed by ventral mesendoderm. Three observations link the expression of tbx6 to ventral mesoderm specification. First, the gene is initially expressed at the onset of gastrulation within a ventrolateral subpopulation of cells that express the pan-mesodermal gene, no tail (Brachyury). Second, the mesoderm-inducing factors activin and bFGF activate tbx6 expression in animal caps. Third, dorsalization of the mesendodermal precursor population following exposure of embryos to lithium ions causes down-regulation of tbx6 transcription. tbx6 is expressed transiently in the involuting derivatives of the ventral mesendoderm, which give rise to nonaxial mesodermal tissues; its expression is extinguished as tissue differentiation progresses. Transcription of tbx6 commences about an hour after initiation of expression of the pan-mesendodermal gene no tail and the organizer gene goosecoid. The dependence of tbx6 expression on no tail activity was examined in no tail mutant embryos. The activation of tbx6 transcription in ventral mesoderm does not depend on no tail gene activity. However, no fail appears to contribute to the maintenance of normal levels of tbx6 transcription and may be required for tbx6 transcription in the developing tail. (C) 1997 Academic Press.