Spatial expression of the amphioxus homologue of Brachyury (T) gene during early embryogenesis of Branchiostoma belcheri
Spatial expression of the amphioxus homologue of Brachyury (T) gene during early embryogenesis of Branchiostoma belcheri
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DOI：
10.1046/j.1440-169x.1995.t01-3-00006.x
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发表时间：
1995-08
期刊：
影响因子：
4.6
通讯作者：
K. Terazawa;N. Satoh
中科院分区：
文献类型：
--
作者：
K. Terazawa;N. Satoh
文昌鱼是原始脊索动物，与脊椎动物有一些共同的解剖特征，例如脊索和背神经索。 Brachyury (T) 基因是脊椎动物脊索分化所必需的，并且该基因的海鞘同源物在发育命运限制时在脊索细胞中表达。为了深入了解脊索动物进化的分子和发育机制，我们扩增了小鼠 T 基因文昌鱼同源物 (BbT1) 的 cDNA 片段，并用它检查了 BbT1 基因的空间表达。原位杂交表明，在卵子以及卵裂和囊胚阶段的早期胚胎中检测不到 BbT1 转录本。明显的杂交信号首先在原肠胚的中胚层中显现出来，但外胚层和内胚层均未显示出信号。当发育进行到神经胚阶段时，信号在原肠背外侧壁的原始体节中变得明显，而原肠背内侧壁的原始脊索发出不太强烈的杂交信号。这些结果表明T基因在文昌鱼中是保守的并且BbT1基因在原肠胚和神经胚的中胚层区域表达。
Amphioxus are primitive chordates that share several common anatomical features with vertebrates, such as a notochord and a dorsal nerve cord. The Brachyury (T) gene is required for notochord differentiation in vertebrates and an ascidian homologue of this gene is expressed in notochord cells at the time of developmental fate restriction. To gain insight into the molecular and developmental mechanisms underlying the evolution of chordates, we amplified a cDNA fragment for an amphioxus homologue (BbT1) of the mouse T gene, with which we examined the spatial expression of the BbT1 gene. In situ hybridization showed that BbT1 transcript was undetectable in eggs, as well as in early embryos at the cleavage and blastula stages. Distinct hybridization signals were first evident in the mesoderm of gastrulae but neither the ectoderm nor endoderm showed the signals. As development proceeded to the neurula stage, the signals became conspicuous in the primordial somite at the dorsolateral wall of the archenteron, while the primordial notochord at the dorsomedian wall of the archenteron emitted less intense hybridization signals. These results suggested that the T gene is conserved by amphioxus and that the BbT1 gene is expressed in the mesodermal region of the gastrula and neurula.