For several years much attention has been paid to the control of flagellar and ciliary movement in eukaryotes by the cyclic nucleotide system. Morton et al. (24) reported that flagellar movement of hamster cauda epididymal spermatozoa could be induced by diluting the semen with a medium containing calcium and that the initiation of beat was accompanied by an increase in the concentration of cyclic AMP within the cells. Garbers et al. (8) and Hoskins (14) reported that cyclic AMP or inhibitors of cyclic nucleotide phosphodiesterase added exogenously to bovine epididymal spermatozoa not only stimulated energy metabolism but activated flagellar motility as well.In addition, the spermatozoa of a wide variety of animals have been shown to contain enzymes related to the cyclic nucleotides such as adenylate cyclase (2,7,12,24), guanylate cyclase (5, 12), cyclic nucleotide phosphodiesterase (2, 12, 24) and phosphoprotein phosphatase (28). An especially large amount of cyclic AMPdependent protein kinase is included in sperm cells (6,15,19,20,25).To investigate the role of the cyclic nucleotide system in the regulation of flagellar motility, we used the Triton models of sea urchin spermatozoa developed by Gibbons
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