Physiological Study of the Mechanism Involved in Ca^<2+> Waves and Ca^<2+> Oscillations in Fertilized Mammalian Eggs

受精时卵细胞内钙离子浓度（Ca）的增加触发卵激活。受精的哺乳动物卵显示传播的钙波和重复的钙瞬变（钙振荡）。本研究旨在分析这些时空Ca信号产生的机制.精卵相互作用如何产生导致卵子钙反应的信号？仓鼠卵质膜上的分子被认为是介导精卵粘附或结合的分子被其配体或抗体刺激，但没有Ca反应。酪氨酸激酶的抑制剂被认为是与膜受体没有阻止精子诱导的钙反应。因此，我们认为，在精卵相互作用的信号转导过程中，胞质内的精子因子（S）可能起着更重要的作用. IP_4激活的Ca内流 关于我们 好的我们从生理学上鉴定了1，3，4，5-四磷酸肌醇（IP_4）激活的仓鼠卵钙内流途径。钙内流提供钙重新填充内质网（ER），其中钙已通过肌醇1，4，5-三磷酸（IP_3）的作用从内质网释放，引起重复的钙释放.利用共聚焦激光扫描显微镜（CLSM）观察到仓鼠受精卵的Ca波在胞质深处传播，细胞核中的Ca也随周围胞质中Ca的增加而增加.结果表明，雌激素受体在卵内呈网状分布，与IP_3受体的分布一致。在未成熟卵母细胞中，ER和IP_3受体呈不均匀分布，呈点状分布于卵母细胞表面和核周围。预注射的笼状IP_3光裂解引起的Ca释放主要发生在核区。这些结果表明，在卵母细胞成熟过程中，ER和IP_3受体的重新分布是获得正常受精能力的先决条件。少

An increase in intracellular calcium ion concentration (Ca) in eggs at fertilization triggers egg activation. Fertilized mammalian eggs show propagating Ca waves and repetitive Ca transients (Ca oscillations). The present study aimed to analyze the mechanism involved in the generation of these spatial and temporal Ca signals.1. How does sperm-egg interaction generate signals leading to Ca responses in eggs? Molecules on the hamster egg plasma membrane that are suggested to mediate sperm-egg adhesion or binding were stimulated by thier ligands or antibodies, but no Ca response was not. The inhibitors of tyrosin kinases which are supposed to be associated with the membrane receptors did not block sperm-induced Ca responses. Thus evidence for the signal genetation in surface molecules was not obtained, leading us to think that cytoplas mic sperm factor (S) introduced into the egg may play more important role in the signal transduction of sperm-egg interaction.2. IP_4-activatee Ca influx p … More athway. We physiologicaly identified inositol 1,3,4,5-tetrakis phosphate (IP_4)-activated Ca influx pathway in hamster eggs. The Ca influx provides Ca to refill the endoplasmic reticulum (ER) from which Ca has been released by the action of inositol 1,4,5-trisphosphate (IP_3), giving rise to repeated Ca release.3. We observed using a confocal laser scanning microscope (CLSM) that the Ca wave in the fertilized hamster egg propagates deep in the cytoplasm, and that Ca in the nucleus also increases comparably with that in the surrouding cytoplasm.4. The ER was stained by injected lipophilic fluorescent dye DiI and observed with CLSM.The ER was found to form a fine network throughout the egg, consistent with the distribution of IP_3 receptors. In immature oocytes the ER as well as IP_3 receptors was distributed inhomogeneously as dence patches in the surface area and aound the nucleus. Ca release induced by photocleavage of preinjected caged IP_3 occurred predominantly in the nuclear zone. These findings indicate that the redistribution of the ER and IP_3 receptors during oocyte maturation is a prerequisite factor for acquisition of the ability to undergo normal fertilization with the Ca waves. Less