The timing of cortical granule fusion, content dispersal, and endocytosis during fertilization of the hamster egg: an electrophysiological and histochemical study.
The timing of cortical granule fusion, content dispersal, and endocytosis during fertilization of the hamster egg: an electrophysiological and histochemical study.
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仓鼠卵受精过程中皮质颗粒融合、内容物分散和内吞作用的时间：一项电生理学和组织化学研究。
DOI：
10.1006/dbio.1994.1085
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发表时间：
1994
影响因子：
2.7
通讯作者：
Stewart-Savage,J
中科院分区：
文献类型：
--
作者：
Kline,D;Stewart-Savage,J
为了确定皮质颗粒胞吐与哺乳动物受精特征重复性钙瞬态之间的时间关系，我们监测了仓鼠卵受精过程中胞吐形成的膜。通过施加375 Hz的3.1 na交流电连续测量膜电容显示皮质颗粒膜的增加。膜电位的同时测量揭示了每一个钙瞬态，通过出现瞬态超极化反应，由于钙激活钾通道在鸡蛋。卵的初始膜电容平均为736±44 pF（平均值±SD；n= 7），受精后第一次超极化反应（HR）开始后4秒内电容增加61±19 pF。所有卵的膜电容在第一次增加后立即逐渐下降，其中5 / 7个卵的膜电容在7.8±4.4 min内恢复到未受精的水平。第一次增加后电容逐渐下降表明内吞作用，荧光标记的葡聚糖内化证实了这一点。在膜电容逐渐下降的同时，随着第二次和以后的hr发生了较小的电容增加。前三个事件的总电容增加平均为72±19 pF，表明电容平均增加约为未受精卵电容的10%。通过用两种不同的荧光染料附着在culinarisagglutinin上标记渗透前后的鸡蛋，我们证明皮质颗粒内容物的分散不会在胞外作用后立即发生。我们的研究结果表明，仓鼠卵皮质颗粒的胞吐与钙的周期性增加密切相关，皮质颗粒的内容物分散缓慢，胞吐后，由于一段时间的内吞作用，卵的表面积恢复到未受精的水平。
To determine the temporal relationship between cortical granule exocytosis and the repetitive calcium transients, which are characteristic of mammalian fertilization, we monitored membrane addition from exocytosis during fertilization of hamster eggs. Continuous measurement of membrane capacitance by applying a 3.1-nA alternating current at 375 Hz showed addition of cortical granule membrane. Simultaneous measurement of membrane potential revealed each calcium transient by the appearance of transient hyperpolarizing responses due to calcium-activated potassium channels in the egg. The initial membrane capacitance of the eggs averaged 736 ± 44 pF (mean ± SD;n= 7) and an increase in capacitance of 61 ± 19 pF occurred within 4 sec of the start of the first hyperpolarizing response (HR) after fertilization. Immediately after the first increase in capacitance there was a gradual decline in membrane capacitance in all eggs and in five/seven eggs the capacitance returned to the unfertilized level in 7.8 ± 4.4 min. The gradual decline in capacitance after the first increase indicated endocytosis, which was confirmed by the internalization of fluorescently labeled dextran. Superimposed on the gradual decline in membrane capacitance were smaller increases in capacitance that occurred with the second and later HRs. The total increase in capacitance from the first three events averaged 72 ± 19 pF, representing an average increase in capacitance of about 10% of the capacitance of the unfertilized egg. By labeling eggs before and after permeabilization with two different fluorochromes attached toLens culinarisagglutinin, we demonstrate that the dispersal of the cortical granules contents does not occur immediately after exocytosis. Our results demonstrate that cortical granule exocytosis in hamster eggs is closely coupled to the periodic increases in calcium, that the contents of the cortical granules are slow to disperse, and that after exocytosis, the surface area of the egg returns to the unfertilized level because of a period of endocytosis.