Cohen-Dayag A, Tur-Kaspa I, Dor J, Mashiach S, Eisenbach M
Department of Membrane Research and Biophysics, Weizmann Institute of Science, Rehovot, Israel.
Proc Natl Acad Sci U S A. 1995 Nov 21;92(24):11039-43. doi: 10.1073/pnas.92.24.11039.
In humans, only a small fraction (2-12%) of a sperm population can respond by chemoattraction to follicular factors. This recent finding led to the hypothesis that chemotaxis provides a mechanism for selective recruitment of functionally mature spermatozoa (i.e., of capacitated spermatozoa, which possess the potential to undergo the acrosome reaction and fertilize the egg). This study aimed to examine this possibility. Capacitated spermatozoa were identified by their ability to undergo the acrosome reaction upon stimulation with phorbol 12-myristate 13-acetate. Under capacitating conditions, only a small portion (2-14%) of the spermatozoa were found to be capacitated. The spermatozoa were then separated according to their chemotactic activity, which resulted in a subpopulation enriched with chemotactically responsive spermatozoa and a subpopulation depleted of such spermatozoa. The level of capacitated spermatozoa in the former was approximately 13-fold higher than that in the latter. The capacitated state was temporary (50 min < life span < 240 min), and it was synchronous with the chemotactic activity. A continuous process of replacement of capacitated/chemotactic spermatozoa within a sperm population was observed. Spermatozoa that had stopped being capacitated did not become capacitated again, which indicates that the capacitated state is acquired only once in a sperm's lifetime. A total sperm population depleted of capacitated spermatozoa stopped being chemotactic. When capacitated spermatozoa reappeared, chemotactic activity was restored. These observations suggest that spermatozoa acquire their chemotactic responsiveness as part of the capacitation process and lose this responsiveness when the capacitated state is terminated. We suggest that the role of sperm chemotaxis in sperm-egg interaction in vivo may indeed be selective recruitment of capacitated spermatozoa for fertilizing the egg.
在人类中，只有一小部分（2% - 12%）的精子群体能够通过趋化作用对卵泡因子作出反应。这一最新发现引发了这样一种假说，即趋化作用为功能性成熟精子（即获能精子，它们具有发生顶体反应和使卵子受精的潜力）的选择性募集提供了一种机制。本研究旨在检验这种可能性。通过用佛波酯12 - 肉豆蔻酸酯13 - 乙酸酯刺激时精子发生顶体反应的能力来鉴定获能精子。在获能条件下，仅发现一小部分（2% - 14%）的精子获能。然后根据精子的趋化活性对其进行分离，这导致了一个富含趋化反应性精子的亚群和一个缺乏此类精子的亚群。前者中获能精子的水平比后者高约13倍。获能状态是暂时的（50分钟 < 寿命 < 240分钟），并且与趋化活性同步。观察到精子群体中获能/趋化精子的持续替换过程。停止获能的精子不会再次获能，这表明获能状态在精子的一生中仅获得一次。一个耗尽获能精子的总精子群体停止了趋化作用。当获能精子再次出现时，趋化活性恢复。这些观察结果表明，精子在获能过程中获得趋化反应性，并在获能状态终止时失去这种反应性。我们认为，精子趋化作用在体内精子 - 卵子相互作用中的作用可能确实是选择性募集获能精子以使卵子受精。
