GRADED CHANGES IN DOSE OF A XENOPUS ACTIVIN-A HOMOLOG ELICIT STEPWISE TRANSITIONS IN EMBRYONIC-CELL FATE
GRADED CHANGES IN DOSE OF A XENOPUS ACTIVIN-A HOMOLOG ELICIT STEPWISE TRANSITIONS IN EMBRYONIC-CELL FATE
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DOI：
10.1038/347391a0
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发表时间：
1990-09-27
期刊：
影响因子：
64.8
通讯作者：
SMITH, JC
中科院分区：
文献类型：
--
作者：
GREEN, JBA;SMITH, JC
XTC-MIF 蛋白是激活素 A 的异种同源物和有效的中胚层诱导因子 1，可以诱导响应的动物极外植体以剂量依赖性方式形成多种不同的细胞类型，较高剂量会引发更多的背前部组织 2。这种分级反应是经典假设的形态发生素3的特征，可能是模式形成的基础，但完整动物帽对 XTC-MIF 的反应仅提供了趋势的粗略指示。在这里，我们报告 XTC-MIF 对分散的卵裂球而不是完整的动物帽的影响。在这些条件下，反应细胞可以清晰地区分纯 XTC-MIF 的剂量，差异小于 1.5 倍。已经发现了两种不同的反应阈值，定义了三种细胞状态。这表明XTC-MIF具有指导作用。脊索和肌肉均在相同的窄剂量范围内诱导。将处理过的细胞与未处理的细胞混合似乎不会改变剂量阈值，这表明至少一些细胞可以稳定地记录所接收的诱导因子的剂量。
THE protein XTC-MIF, aXenopushomologue of activin A and a potent mesoderm-inducing factor1, can induce responding animal pole explants to form several different cell types in a dose-dependent manner, higher doses eliciting more dorso-anterior tissues2. This graded response, characteristic of classically postulated morphogens3, may underlie pattern formation, but the response of intact animal caps to XTC-MIF provides only a crude indication of trends. Here we report the effects of XTC-MIF on dispersed blastomeres rather than intact animal caps. Under these conditions, responding cells distinguish sharply between doses of pure XTC-MIF differing by less than 1.5-fold. Two different response thresholds have been found, defining three cell states. This suggests that XTC-MIF has an instructive effect. Notochord and muscle are both induced in the same narrow dose-range. Mixing treated with untreated cells does not seem to shift the dose thresholds, showing that at least some cells can stably record the received dose of inducing factor.