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A study of an egg-activating molecule in the sperm cytoplasm

精子细胞质中卵子激活分子的研究

基本信息

批准号：
12680717
负责人：
IWAO Yasuhiro
金额：
$ 2.3万
依托单位：
Yamaguchi University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2002
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12680717/
关键词：
Fertilization Amphibians Mammals Ca cell division 哺乳類カルシウムイモリ細胞分裂 Ca 両生類細胞周期再開

项目摘要

In our study, we have found the following major results. Unfertilized eggs of the newt, Cynops pyrrhogaster, are arrested at the second meiotic metaphase. A transient increase of [Ca^<2+>]_i, which is triggered by fertilizing sperm and propagates over the egg cortex as Ca^<2+> wave, is a primary signal to cause egg activation. The injection of an extract of Cynops sperm (SE) into the unfertilized eggs induced the wave-like [Ca^<2+>]_i increase, and then the eggs underwent activation and resumption of meiosis. In the SE-injected eggs, not only degradation of cyclin B1, but also DNA replication was confirmed. When SE had been boiled or treated with Proteinase K before injection, the activity to cause egg activation was lost. Preinjection of Ca^<2+>-chelator BAPTA before SE-injection inhibited egg activation. These results indicate that a heat-labile and proteinous factor in sperm cytoplasm induces a transient increase of [Ca^<2+>]_i indispensable for egg activation. Injection of IP_3 into unfertilized eggs caused [Ca^<2+>]_i increase and egg activation, but injection of cADP-ribose did not. In addition, preinjection of heparin, an inhibitor of IP_3 receptors, prevented egg activation by fertilizing sperm or by SE-injection. These results indicate that not only fertilization, but also SE-injection induces [Ca^<2+>]_i increase through the IP_3 receptors, rather titan rianodine receptors.

在我们的研究中，我们发现了以下主要结果。在第二次减数分裂中期，食蟹猴的未受精卵停止生长。由精子受精触发的[Ca^&lt；2+&gt；]_i的瞬时升高是引起卵子激活的主要信号，它以Ca^&lt；2+&gt；波的形式通过卵子皮质传播。向未受精卵中注入食蟹精子(SE)提取液后，[Ca~(2+)~(2+)]_i呈波浪状升高，卵子开始激活并恢复减数分裂。在注射SE的卵子中，不仅证实了Cyclin B1的降解，而且证实了DNA的复制。当SE在注射前被煮沸或用蛋白酶K处理时，引起卵子激活的活性丧失。在注射SE前预先注射Ca~(2+)&Gt；-螯合剂BAPTA可抑制卵子的激活。这些结果表明，精子胞质中的一种不稳定的蛋白因子导致卵子激活所必需的[Ca~(2+)]_i一过性升高。未受精卵注射IP_3可引起[Ca~(2+)]_i升高和卵子激活，而注射cADP-核糖则无此作用。此外，预先注射IP_3受体的抑制剂肝素可通过使精子受精或注射SE来阻止卵子激活。这些结果表明，不仅受精，而且注射SE也通过IP_3受体而不是Tian核苷受体诱导[Ca~(2+)]_i升高。