SIGNAL TRANSDUCTION AT FERTILIZATION

在精子与海胆接触后的第一分钟内， 在青蛙卵中，一系列显著的信号来回传递 在精子和卵子质膜之间。 接触 受精精子导致卵浆中的离子通道打开 膜，使其脱附。 这种谴责阻止了 其他精子使卵子受精。 与此同时， 精子启动了一系列的生化反应 事件，导致鸡蛋进行胞吐作用的皮质 囊泡并开始开始发育。 这项建议的一个具体目标是审查这一途径， 将精卵相互作用耦合到离子通道开放， 皮质小泡胞吐作用。 我们将检验这样一个假设， 精子激活了卵浆中的受体 膜，受体激活G蛋白， 刺激PIP 2磷酸二酯酶，导致InsP 3产生 释放Ca 2+。 Ca 2+释放被认为是导致离子通道 通过涉及Ca 2 +/钙调蛋白- 依赖性磷酸酶 这些方法将包括显微注射 以及生物化学方法，包括使用 克隆抗体 另一个具体目标涉及调查如何改变 卵子的膜电位调节精卵融合。 我们将 检验两个假设：首先，我们将检验 精子膜含有带正电荷的融合体 解释精卵电压依赖性的蛋白质 核聚变 其次，我们将研究另一种可能性，即 卵膜含有精子受体， 精子在卵子的外表面取决于卵子的 膜电位 这些方法将涉及跨物种 受精，脂质双层技术，以及 单克隆抗体和蛋白酶的鸡蛋在不同的电压。 这项工作对人类发展研究的意义 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。 基础科学背景最终可能会发现 应用于实际问题，如避孕和 不孕

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.