Subcortical rotation in Xenopus eggs: an early step in embryonic axis specification.
Subcortical rotation in Xenopus eggs: an early step in embryonic axis specification.
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DOI：
10.1016/0012-1606(87)90411-8
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发表时间：
1987-10
影响因子：
2.7
通讯作者：
Jean-Paul Vincent;John C. Gerhart
中科院分区：
文献类型：
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作者：
Jean-Paul Vincent;John C. Gerhart
在第一个细胞周期中，两栖动物卵的皮层下细胞质相对于其表面发生旋转。应用于卵外周的尼罗蓝斑点随着皮层下细胞质移动，并使旋转直接可观察到（J. P. Vincent，G. F.奥斯特和J. C. 03 The Dog（1986）113，484）。我们以前已经证明，旋转方向准确地预测了由卵子发育的胚胎轴的方向。这表明皮质下旋转轴规范的重要作用。在这份报告中，我们提供了两种实验证据旋转的重要作用，并对其他并发的细胞质运动，如在动物半球的精子进入点的皮质下细胞质的收敛的作用。首先，双卵型卵只发育出一个胚胎轴，它的方向与单次旋转运动的方向准确地一致，而不是与动物半球中形成的两个会聚焦点一致。旋转可能会改变植物性半球，而不是动物性半球，因为尽管动物皮质下运动发生了高度改变，但双精子卵的轴向发育是正常的。其次，我们表明，旋转量与背侧发展的程度。植物半球的紫外线照射，或鸡蛋的冷休克，有效地抑制旋转。当没有旋转时，就没有背侧发育。平均而言，在卵种群中，旋转量的增加与胚胎体轴的背侧结构的前极限的增加相关。然而，个别部分抑制的鸡蛋在一定量的运动后形成的轴的量有很大差异。此外，蛋通常旋转超过一个完整轴的发展所需的。这些研究结果表明，旋转，虽然必不可少的，不直接图案的前后尺寸的身体轴，但触发的反应系统，不同的鸡蛋在其敏感性旋转。这个系统是通过在旋转前不久将鸡蛋暴露于D2O来人工敏化的。我们发现，D2O处理的鸡蛋产生广泛的轴，尽管非常有限的旋转，往往发展成hyperdorsal胚胎。然而，像正常的鸡蛋一样，它们依赖于旋转，如果被消除，就不能形成背部结构。
The amphibian egg undergoes a rotation of its subcortical cytoplasm relative to its surface during the first cell cycle. Nile blue spots applied to the egg periphery move with the subcortical cytoplasm and make rotation directly observable (J.-P. Vincent, G. F. Oster, and J. C. Gerhart (1986).Dev. Biol.113,484). We have previously shown that the direction of rotation accurately predicts the orientation of the embryonic axis developed by the egg. This suggests an important role for subcortical rotation in axis specification. In this report, we provide two kinds of experimental evidence for the essential role of rotation, and against a role for other concurrent cytoplasmic movements such as the convergence of subcortical cytoplasm toward the sperm entry point in the animal hemisphere. First, dispermic eggs develop only one embryonic axis, which is oriented accurately in line with the direction of the single rotation movement and not with the two convergence foci that form in the animal hemisphere. Rotation probably modifies the vegetal, not animal, hemisphere since axial development is normal in dispermic eggs despite highly altered animal subcortical movement. Second, we show that the amount of rotation correlates with the extent of dorsal development. UV irradiation of the vegetal hemisphere, or cold shock of the egg, inhibits rotation effectively. When there is no rotation, there is no dorsal development. On average within the egg population, increasing amounts of rotation correlate with the increasingly anterior limit of the dorsal structures of the embryonic body axis. However, individual partially inhibited eggs vary greatly in the amount of axis formed following a given amount of movement. Furthermore, the egg normally rotates more than is necessary for the development of a complete axis. These findings suggest that rotation, although essential, does not directly pattern the antero-posterior dimension of the body axis, but triggers a response system which varies from egg to egg in its sensitivity to rotation. This system is artificially sensitized by exposure of the egg to D2O shortly before rotation. We show that D2O-treated eggs produce extensive axes despite very limited rotation, often developing into hyperdorsal embryos. However, like normal eggs, they depend on rotation and cannot form dorsal structures if it is eliminated.