DIRECT AND CONTINUOUS ASSESSMENT BY CELLS OF THEIR POSITION IN A MORPHOGEN GRADIENT
DIRECT AND CONTINUOUS ASSESSMENT BY CELLS OF THEIR POSITION IN A MORPHOGEN GRADIENT
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DOI：
10.1038/376520a0
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发表时间：
1995-08-10
期刊：
影响因子：
64.8
通讯作者：
MAHONY, D
中科院分区：
文献类型：
--
作者：
GURDON, JB;MITCHELL, A;MAHONY, D
根据形态梯度的概念(1-5)，胚胎的一个部分的细胞分泌可扩散的分子(形态原)，这些分子扩散到附近的细胞，并在不同的阈值浓度下激活基因。格林和史密斯(6，7)的生化实验有力地支持了脊椎动物发育中形态梯度机制的运作，他们在两栖类囊胚细胞中诱导了不同类型的基因表达，暴露于激活素浓度的微小变化，但最近的报道使这些实验的解释变得复杂，这些细胞在接触激活素3小时后进行基因表达测试，但未能显示先前报道的15小时(6，7)的分级反应。这一结果表明细胞通过一种间接的机制识别它们在梯度中的位置，在这里，我们通过对含有激活素负载的珠子(11)的囊胚组织的原位分析得出结论，细胞以一种类似于棘轮的方式直接对变化的形态原浓度做出反应。
ACCORDING to the morphogen gradient concept(1-5), cells in one part of an embryo secrete diffusible molecules (morphogens) that spread to other nearby cells and activate genes at different threshold concentrations, Strong support for the operation of a morphogen gradient mechanism in vertebrate development has come from the biochemical experiments of Green and Smith(6,7), who induced different kinds of gene expression in amphibian blastula cells exposed to small changes in activin concentration, But the interpretation of these experiments has been complicated by recent reports that cells tested for gene expression 3 hours after exposure to activin fail to show the graded response previously reported at 15 hours(6,7), a result suggesting that cells recognize their position in a gradient by an indirect mechanism, Here we conclude from the in situ analysis of blastula tissue containing activin-loaded beads(11) that cells respond directly to changing morphogen concentrations, in a way that resembles a ratchet-like process.