Experimental control of the site of embryonic axis formation in Xenopus laevis eggs centrifuged before first cleavage.
Experimental control of the site of embryonic axis formation in Xenopus laevis eggs centrifuged before first cleavage.
复制标题
第一次卵裂前离心的非洲爪蟾卵胚胎轴形成位点的实验控制。
DOI：
10.1016/0012-1606(85)90035-1
复制
发表时间：
1985
影响因子：
2.7
通讯作者：
Gerhart,JC
中科院分区：
文献类型：
--
作者：
Black,SD;Gerhart,JC
在非洲爪蟾中，背部结构通常从精子进入的一侧对面的卵区域发育而来。重力是已知的影响这种地形关系的鸡蛋倾斜从正常的垂直方向在第一次卵裂前的时期。已经详细探索了这种效果，使用低速离心（10- 50 g）持续时间较短（4 min）。将卵固定在明胶中，并使其动物-植物轴与力矢量成90°，卵的精子进入点（SEP）侧朝向或远离转子中心。结果表明，卵在受精至第一次卵裂的时间间隔内，对离心力有三个不同的反应期：（1）在0.4（第一次卵裂时间间隔的40%）之前，卵对离心力非常敏感，无论SEP在离心力场中的位置如何，卵的背侧结构都从卵的中央侧开始发育。因此，胚胎的背侧结构与从转子中心用SEPaway离心的卵的正常结构相反。(2)在0.4 - 0.7期间，卵对离心力仍然非常敏感，并且从其中央花瓣侧开始发育背侧结构，无论SEP在离心场中的位置如何。因此，胚胎的背侧结构从正常的卵中反转，其中SEP朝向转子的中心离心。(3)在0.7-1.0期间，卵对离心力的抵抗力越来越大，并在SEP侧的正常位置形成背侧结构。在某些卵离合器中，通过50 g离心，然后在1 g下延长90°离轴倾斜，可以克服这种阻力。在第二个细胞周期的中途，有一个短暂的离心力敏感期。这些结果进行了讨论，在细胞周期的不同时间发生在鸡蛋中的细胞质重排的类型，并在背轴发展的决定因素的细胞质本地化的过程。
InXenopus laevis, the dorsal structures normally develop from regions of the egg opposite the side of sperm entry. Gravity is known to affect this topographic relationship in eggs inclined obliquely from their normal vertical orientation in the period before first cleavage. This effect has been explored in detail, making use of low-speed centrifugation (10–50g) for short durations (4 min). Eggs were immobilized in gelatin and oriented with their animal-vegetal axes 90° to the force vector, with the sperm entry point (SEP) side of the egg either toward or away from the center of the rotor. It has been found that the egg shows three distinct periods of response to centrifugal force in the interval from fertilization to first cleavage: (1) Prior to 0.4 (40% of the first cleavage interval), the egg is very sensitive to centrifugal force and develops dorsal structures from itscentrifugalside, regardless of the position of the SEP in the centrifugal field. Thus, the dorsal structures of the embryo are reversed from normal in eggs centrifuged with the SEPawayfrom the center of the rotor. (2) In the period 0.4 to 0.7, the egg is still very sensitive to centrifugal force and develops dorsal structures from itscentripetalside, regardless of the position of the SEP in the centrifugal field. Thus, the dorsal structures of the embryo are reversed from normal in eggs centrifuged with the SEPtowardthe center of the rotor. (3) In the period 0.7–1.0, the egg becomes increasingly resistant to centrifugal force and forms dorsal structures at the normal position opposite the SEP side. This resistance can be overcome in some egg clutches by 50gcentrifugation followed by prolonged 90° off-axis inclination at 1g. Midway in the second cell cycle, there is a brief period of sensitivity to centrifugal force. These results are discussed in terms of the types of cytoplasmic rearrangements occurring in the egg at different times of the cell cycle, and in terms of the process of cytoplasmic localization of determinants of dorsal axial development.