Analysis of sperm-dependent electrical responses during amphibian fertilization.

研究了离子取代、离子通道抑制剂和电压夹紧对蟾蜍和蝾螈两种两栖动物正常受精过程中卵质膜离子通透性的影响。在成熟蟾蜍卵的受精过程中，我们观察到在前面描述的受精电位的正平台之前，会产生一个尖峰状的去极化电位。像高原一样，这种尖峰状电位是由对Cl^-或I^-等卤化物的渗透性增加介导的。此外，在未成熟蟾蜍卵母细胞的多精子受精中，每次精子进入都会引起相同的穗状电位。这些尖峰电位取决于精子对卵子的渗透。另一方面，蝾螈卵子受精过程中没有明显的电变化，但卵子引发了与每个精子进入相对应的小的超极化电位。目前还不清楚是什么离子通道导致了这些超极化。然而，根据这项调查，我们发现两栖动物的卵子引发了依赖于精子进入的电变化。在蟾蜍卵与蝾螈精子的杂交受精中，我们没有发现尖状电位，但在受精电位的正平台之前，卵子引发了一个逐渐变化的超极化，这在正常受精中从未观察到。这种超极化主要是由一价阳离子（如Na^+）的渗透性增加介导的。我们没能找到蟾蜍精子能使蝾螈卵受精的条件，但我们发现蝾螈精子能使蝾螈卵受精。蝾螈卵引发了几个小的超极化，这些超极化与每个精子入口很好地对应。总体结果表明，蟾蜍和蝾螈卵打开的离子通道非常不同，这取决于进入卵子的精子的种类。减轻这些电位变化的离子通道可能存在于精子的质膜中，也可能在受精时的膜融合过程中被提供到卵子的质膜中。少

We investigated the changes of ionic permeabilities in egg plasma membrane during normal fertilization on anran (toad) and urodele (newt) amphibians with ionsubstitution, inhibitors of ionic channels, and voltage-clamping. In the fertilization of mature toad eggs, we observed the elicitaiton of a spike-like depolarization potential before the positive platea of fertilization potential that has been descrived previously. This spike-like potential is, like the platea, mediated by increased permeabilty to halides such as Cl^- or I^-. In addition, in the polyspemic fertilization of immature toad oocytes, the same spike-like potential was elicited in response to each sperm entranece. These spike potenial are depends on the penetration of sperm into the egg. On the other hand, there is no pronounced electrical changes during the fertilization of newt eggs, but the egg elicited small hyperpolarizing potentials that corresponded to each sperm entrance. It is not yet clear what ionic channels p … More articiapte to these hyperpolarization. According to this investigation, howerver, we have found that the eggs of amphibians elicit the electrical changes that depend on the sperm entrance.In the cross-fertilization between the toad eggs and the newt sperm, we were not able to find the spike-like potential, but the eggs elicited a gradually-changed hyperpolarization before the positive platea of fertilization potential, that was never observed in the normal fertilization. This hypserpolarization is mediated by mainly an increased permeability of monovalent cations such as Na^+. We were not able to find the condition that the toad sperm can fertilize the newt eggs, but we found that the salamander sperm were able to fertilize the newt eggs. The newt eggs elicited several smal hyperpolarization that corresponded well with each seprm entrance. Overall results indicate that both toad and newt eggs open very different ionic channels depending on the species of sperm that enter the eggs. The ionic channels that meiated these potential changes might be in the sperm plasma membrane and might be provided into the egg plasma membrane during membrane fusion at the fertilization. Less