RUI: Glycosidase Release and the Block to Polyspermy in Ascidian Eggs

兰伯特博士和古德博士将研究一个阻止多精受精的基因组， 海鞘卵 根据他们的模型， 卵的卵黄层上的糖苷。 的增加 结合到卵黄膜上的精子数量， 快速下降。 这种结合力的下降有助于确保只有一个 单个精子进入卵子。 精子结合受到 Na+依赖性的糖苷酶释放， 卵黄膜精子受体 他们假设 糖苷酶最初与卵膜连接， 在受精时迅速排出。 事实上， 磷脂酶C可以将酶从未受精卵中释放出来 这表明该酶与膜磷脂相连。 他们的模型包括将糖苷酶连接到 磷脂酰胆碱和Na+依赖性激活 引起酶释放的磷脂酶。 糖苷酶和 磷脂酶将被分离和广泛表征。 将针对这两种蛋白质制备抗体以进行超微结构检查 酶定位 并对释放机理进行了探讨 通过使用磷脂酶激动剂和拮抗剂， 还通过直接测量中的磷脂酶活性， 未受精卵和受精卵。 G蛋白的作用， 海鞘卵激活中的离子也将被探测。 %%% 尽管每个卵子会产生数百万个精子，但如果更多的话 比一个精子进入卵子，卵裂是严重异常的， 死亡是不可避免的因此，阻止进入 额外的精子对生育能力至关重要。 兰伯特博士和古德博士将进一步了解这一点 通过研究精子进入的分子细节， 在海鞘系统中的阻塞。

Dr.Lambert and Dr.Goode will study a block to polyspermy in the Ascidian egg. According to their model, the sperm bind to glycosides on the vitelline coat of the egg. An increase in the number of sperm binding to the vitelline coat is followed by a rapid decline. This decline in binding helps insure that only a single sperm enters the egg. Sperm binding is inhibited by the Na+-dependent release of a glycosidase that modifies the vitelline coat sperm receptors. They hypothesize that the glycosidase is initially linked to the egg membrane and is rapidly discharged at fertilization. The fact that detergents and Phospholipase C can free the enzyme from the unfertilized egg suggest that the enzyme is linked to a membrane phospholipid. Their model includes linkage of the glycosidase to a phosphatidylcholine and the Na+-dependent activation of a phospholipase that causes enzyme release. The glycosidase and phospholipase will be isolated and extensively characterized. Antibodies will be prepared to both proteins for ultrastructural enzyme localization. The mechanism of release will be probed through the use of phospholipase agonists and antagonists and also through the direct measurement of phospholipase activity in unfertilized and fertilized eggs. The role of G proteins and ions in Ascidian egg activation will also be probed. %%% Although millions of sperm are produced for each egg, if more than a single sperm enters the egg,cleavage is grossly abnormal and death is inevitable. As a consequence, blocking the entry of additional sperm is of critical importance to fertility. Dr.Lambert and Dr. Goode will further the understanding of this phenomenon by studying the molecular details of sperm entry and blocking in the Ascidian system.