SIGNAL TRANSDUCTION AT FERTILIZATION

在精子接触海胆后的第一分钟内 青蛙卵，一系列引人注目的信号来回传递 精子和卵子质膜之间。与客户联系 使精子受精导致卵子血浆中的离子通道打开 膜，使其去极化。这种贫化阻止了 使卵子受精的其他精子。同时，与 使精子受精启动了一系列生化反应 导致卵子大脑皮层发生胞吐的事件 囊泡并开始发育。 这项提议的一个具体目标是检查这条路径 将精子-卵子相互作用与离子通道开放和 皮质囊泡胞吐。我们将检验这一假设 受精的精子激活卵子血浆中的受体 膜，并且受体激活一种G蛋白，该G蛋白 刺激PIP2磷酸二酯酶，导致InsP3的产生 和钙离子的释放。钙离子的释放被认为是引起离子通道的原因 通过一条涉及钙/钙调蛋白的途径开放和胞吐 依赖的磷酸酶。这些方法将涉及微量注射。 以及生化方法，包括使用 单克隆抗体。 另一个具体目标涉及调查 卵子的膜电位调节精子和卵子的融合。我们会 考察两个假设：首先，我们将考察 精子膜上含有带正电的熔合体 精卵电压依赖性的蛋白质 核聚变。第二，我们将研究另一种可能性，即 卵膜含有一种精子受体，它暴露在 卵子外表面的精子取决于卵子的 膜电位。这些方法将涉及跨物种。 受精、脂质双层技术及其应用 在不同电压下对鸡蛋的单抗和蛋白酶。 这项工作对研究人类发展的意义 我们在工作中发现的细胞生物学原理 无脊椎动物和两栖动物将成为未来研究的基础 哺乳动物的生命。基础科学背景可能最终会发现 在实际问题上的应用，如避孕和 不孕不育。

Within the first minute after sperm contact with a sea urchin or frog egg, a remarkable series of signals passes back and forth between sperm and egg plasma membranes. Contact with the fertilizing sperm causes ion channels to open in the egg plasma membrane, causing it to depolarize. This deplorization prevents other sperm from fertilizng the egg. Meanwhile, contact of the fertilizing sperm has set in motion a sequence of biochemical events which causes the egg to undergo exocytosis of its cortical vesicles and to begin development. One specific aim of this proposal involves examining the pathway coupling sperm-egg interaction to ion channel opening and cortical vesicle exocytosis. We will examine the hypothesis that the fertilizing sperm activates a receptor in the egg plasma membrane, and that the receptor activates a G-protein, which stimulates PIP2 phosphodiesterase, leading to InsP3 production and Ca2+ release. Ca2+ release is proposed to cause ion channel opening and exocytosis by a pathway involving a Ca2+/calmodulin- dependent phosphatase. The methods will involve microinjection as well as biochemical approaches, including the use of monoclonal antibodies. The other specific aim involves investigating how a change in the egg's membrane potential regulates sperm-egg fusion. We will examine two hypotheses: first, we will examine the possibility that the sperm membrane contains a positively charged fusion protein which accounts for the voltage-dependence of sperm-egg fusion. Second, we will examine an alternate possibility, that the egg membrane contains a sperm receptor whose exposure to sperm on the external surface of the egg depends on the egg's membrane potential. The methods will involve cross-species fertilization, lipid bilayer techniques, and application of monoclonal antibodies and proteases to eggs at various voltages. The significance of this work to the study of human development is that the cell biological prinicples we discover in our work invertebrates and amphibians will form a basis for future studies of mammals. The basic science background may ultimately find applications to practical problems such as contraception and infertility.