The Fast Block to Polyspermy

多精受精卵通常在短时间的异常受精后死亡。 胚胎发生，但许多动物和至少两种植物的卵 通过"快"和"慢"阻断防止多精受精。 的 这里提出的研究将扩展对 使用岩藻糖的快速阻断（短暂的离子介导的阻断） 藻类作为模型系统。 生理和电生理 技术将被用来描述离子依赖性的 快速阻断和受精潜力。 的影响 将在几种岩藻多糖中评价多精受精精子/卵子比率 物种，以及关于受精和精子/卵子比例的数据， 场将被收集。 自然水平的多精受精 通过将瓦片放置在 潮间带及其定居发展的观察 受精卵 这类研究将探讨以下可能性： 受精卵的补充受快速阻断失败的影响 在自然渗透压期间。 信息很少 在植物的多精细胞块中可以获得。 拟议工作 将在这一领域做出重大贡献， 对岩藻的研究，并通过检查几个 其他海洋和淡水藻类的离子存在 阻止多精受精 %%% 由一个以上精子受精的卵子通常在受精后死亡。 一个短时期的不正常的胚胎发生。 许多生物体中 多精受精是由两个连续的机制防止-快速 动作块和慢一个。 快速阻滞由 在第一个离子流之后立即开始开始的瞬时离子流 受精 尽管它广泛存在，但 很少有生态数据可用于评估 在自然情况下的这种快速阻挡， 操纵离子条件或精子/卵子的实验室 比率很高。 布劳利博士提议调查 自然情况下使用岩藻藻类在潮汐池，其中离子 条件会有很大的不同因此，它将获得生态 目前缺乏天然精子/卵子的数据 浓度，并评估多精受精的常见程度， 自然

Polyspermic eggs usually die after a short period of abnormal embryogenesis, but eggs of many animals and at least two plants are protected from polyspermy by "fast" and "slow" blocks. The studies proposed here will extend out general understanding of the fast block (a transient, ion-mediated blockage) using fucoid algae as a model system. Physiological and electrophysiological techniques will be used to describe the ionic dependence of the fast block and the fertilization potential. The effect of the sperm/egg ratio on polyspermy will be evaluated in several fucoid species, and data on fertilization and sperm/egg rations in the field will be collected. Natural levels of polyspermy will be determined by placing tiles within appropriate portions of the intertidal zone and observing the development of colonizing zygotes. Such studies will examine the possibility that recruitment of zygotes is affected by failure of the fast block during periods of natural osmotic stress. Little information is available on polyspermic blocks in plants. The proposed work will make a significant contribution in this area, both through the proposed studies of fucoid algae and by examining several other marine and freshwater algae for the presence of an ionic block to polyspermy. %%% Eggs that are fertilized by more than one sperm usually die after a short period of abnormal embryogenesis. In many organisms polyspermy is prevented by two successive mechanisms- a fast acting block and a slower one. The fast block is mediated by transient ionic fluxes that begin immediately after the first fertilization. In spite of its widespread occurrence, there is little ecological data available to evaluate the importance of this fast block under natural circumstances as opposed to in the laboratory where ionic conditions are manipulated or sperm/egg ratios are high. Dr. Brawley proposes to investigate the natural situation using fucoid algae in tide pools where ionic conditions can vary dramatically. She will thus obtain ecological data that are currently lacking on natural sperm/egg concentrations, and an evaluation of how common polyspermy is in nature.