Phosphorylation of a protein and the initiation of flagellar motility in rainbow trout spermatozoa.

Abstract

In many higher organisms, the life span of an individual commences at the time when two gametes, an egg and a spermatozoon, fuse together. From that very moment, ageing of an individual organism inevitably starts. The drama of reproduction of life has several prologues, for example maturation and spawning of gamates. Concerning the latter event, especially release of sperm cells, it is well known that spermatozoa which are quiescent in the male reproductive organ, start to move when they are released into the spawning ground. At this moment, there must be some means for the sperm cells to detect the change of environment and subsequently to initiate the flagellar motility. This idea has been proposed more than half a century by sir James Gray who described that initiation of motility in sea urchin spermatozoa occurs by the mechanical dilution whereby spawned sperm obtain open space for movement1. Furthermore, a number of investigators tried to find the factor(s) indispensable for the initiation of sperm motility by studying mainly marine invertebrates. Nevertheless, the mechanism underlying the initiation of sperm motility has been obscure.