PDF(Pubmed)
Abstract：
In sea urchins, the sequence of the cellular and molecular events characterizing the fertilization process has been intensively studied. We have learned that to activate the egg, the fertilizing sperm must undergo morphological modifications (the acrosome reaction, AR) upon reaching the outer gelatinous layer enveloping the egg (egg jelly), which triggers the polymerization of F-actin on the sperm head to form the acrosomal process. The AR exposes bindin, an adhesive sperm protein essential for the species-specific interaction with the cognate receptor on the egg vitelline layer. To investigate the specific roles of the egg jelly and vitelline layer at fertilization of sea urchin eggs, Paracentrotus lividus eggs were incubated in acidic seawater, which removes the egg jelly, i.e., experimental conditions that should prevent the occurrence of the AR, and inseminated in the same medium. At variance with the prevailing view, our results have shown that these dejellied P. lividus eggs can still interact with sperm in acidic seawater, albeit with altered fertilization responses. In particular, the eggs deprived of the vitelline layer reacted with multiple sperm but with altered Ca2+ signals. The results have provided experimental evidence that the plasma membrane, and not the vitelline layer, is where the specific recognition between gametes occurs. The vitelline layer works in unfertilized eggs to prevent polyspermy.
摘要：
在海胆中，表征受精过程的细胞和分子事件的顺序已经被深入研究。我们已经了解到，要激活鸡蛋，受精的精子必须进行形态学修饰（顶体反应，AR）到达包裹鸡蛋（蛋冻）的外部凝胶层，这触发了F-肌动蛋白在精子头上的聚合以形成顶体过程。AR暴露了宾丁，一种粘附的精子蛋白，对于物种特异性与卵黄质层上的同源受体相互作用至关重要。为了研究卵冻和卵黄层在海胆卵受精中的特定作用，Paracentrotuslividus卵在酸性海水中孵育，去除蛋冻，即，应该防止AR发生的实验条件，在同一培养基中授精。与普遍观点不同，我们的结果表明，这些脱胶假单胞菌卵在酸性海水中仍然可以与精子相互作用，尽管受精反应改变了。特别是,被剥夺卵黄层的卵与多个精子反应，但Ca2信号改变。这些结果提供了实验证据,而不是卵黄层，是配子之间发生特定识别的地方。卵黄层在未受精卵中起作用，以防止多精子症。
