The activation wave of calcium in the ascidian egg and its role in ooplasmic segregation.
The activation wave of calcium in the ascidian egg and its role in ooplasmic segregation.
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DOI：
10.1083/jcb.110.5.1589
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发表时间：
1990-05
影响因子：
7.8
通讯作者：
Jaffe, L F
中科院分区：
文献类型：
--
作者：
Speksnijder, J E;Sardet, C;Jaffe, L F
我们使用成像系统研究了海鞘 Phallusia mammillata 中的卵激活和卵质分离，该系统使我们能够同时监测卵形态和钙依赖性水母发光蛋白发光。授精后，一股高度升高的游离钙波以 8-9 微米/秒的峰值速度穿过卵子。在没有外部钙的情况下受精卵中也可以看到类似的波。通过与 WGA 一起孵化的人工激活也会产生钙波，尽管其时间和空间特征与精子激活的卵子不同。在精子核进入后的运动被细胞松弛素 D 阻断的卵子中，精子紫苑在钙波先前开始的位置形成。这表明钙波从精子进入的地方开始。在 70% 的卵子中，钙波始于动物半球，这证实了之前的观察结果，即精子优先进入卵子的这一部分（Speksnijder, J. E., L. F. Jaffe, and C. Sardet. 1989. Dev. Biol. 133:180-184）。钙波开始后约 30-40 秒，动物极附近开始出现较慢（1.4 微米/秒）的皮质收缩波。它将皮质下细胞质带到收缩极，该收缩极远离精子进入的一侧，与植物极成 50 度角。我们认为，精子进入点可能会通过导致卵质分离的方向远离植物极而影响卵质分离的方向，大概是通过钙波的某种作用。
We have studied egg activation and ooplasmic segregation in the ascidian Phallusia mammillata using an imaging system that let us simultaneously monitor egg morphology and calcium-dependent aequorin luminescence. After insemination, a wave of highly elevated free calcium crosses the egg with a peak velocity of 8-9 microns/s. A similar wave is seen in egg fertilized in the absence of external calcium. Artificial activation via incubation with WGA also results in a calcium wave, albeit with different temporal and spatial characteristics than in sperm-activated eggs. In eggs in which movement of the sperm nucleus after entry is blocked with cytochalasin D, the sperm aster is formed at the site where the calcium wave had previously started. This indicates that the calcium wave starts where the sperm enters. In 70% of the eggs, the calcium wave starts in the animal hemisphere, which confirms previous observations that there is a preference for sperm to enter this part of the egg (Speksnijder, J. E., L. F. Jaffe, and C. Sardet. 1989. Dev. Biol. 133:180-184). About 30-40 s after the calcium wave starts, a slower (1.4 microns/s) wave of cortical contraction starts near the animal pole. It carries the subcortical cytoplasm to a contraction pole, which forms away from the side of sperm entry and up to 50 degrees away from the vegetal pole. We propose that the point of sperm entry may affect the direction of ooplasmic segregation by causing it to tilt away from the vegetal pole, presumably via some action of the calcium wave.