| Budget Amount *help |
¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 1988: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1987: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Research Abstract |
The aim of the present reaearch project is to investigate the intracellular motility initiation factor for mammalian spermatozoa. Since adenosine 3',5'-monophosphate (cyclic AMP) has been identified as the intracellullar motility initiation factor for salmonid fish spermatozoa, this uncleotide is seemed to be the intracellular motility initiation factor for mammalian spermatozoa. Moreover, demembraneted spermatozoa of hamster became motile only when ATP and cyclic AMP were added together. The intracellular concentration of cyclic AMP, which was determined by redioimmunoassay, increased immediately after the motility initiated in hamster spermatozoa. This increase was provided to be due to an activation of adenylate cyclase upon the initiation of the sperm motility. Furthermore, electron microscopical observation proved that this enzyme distributed at only flagella part, not at acrosomal region, was activated during the motility initiation process.
Since activity of phosphodiesterase rem
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ained low for a few minutes after the initiation of sperm motility, cyclic amp was able to accumulate in the spermatozoa. However, the phosphodiesterase activity increased after every spermatozoa became to move, the intracellular cyclic amp level gradually decreased. These observation strongly suggest that cyclic AMP is the real intracellular motility initiation factor for the spermatozoa of hamster. Quite similar results were obtained on the spermatozoa of boar. As adenylate cyclase activity is regulated by calcium ion, effect of this ion on the initiation of the spermatozoa of hamster was examined, because the activator of this enzyme is expected to be an external motility initiation factor. When both internal and external free calcium ion was completely removed, the spermatozoa never became motile. But addition of this ion externally, the spermatozoa gradually initiated to move. These results indicate that free calcium ion must closely correlated with the motility initiation mechanism of the spermatozoa. Less
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