Induction of motility of apyrene spermatozoa and dissociation of Eupyrene sperm bundles of the silkmoth,Bombyx mori, by initiatorin and trypsin

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Abstract
The activator, or inducer of motility, of apyrene spermatozoa of the silkmoth, Bombyx mori, was shown to be present in the posterior glandula (g.) prostatica. The activity of this factor in this gland was lost by boiling at 100°C for 10 min. Bundles of eupyrene sperm were dissociated by treatment with either a g. prostatica homogenate or trypsin, and their dissociation was concentration-dependent. On the contrary, for activation of apyrene sperm, the optimal trypsin concentration was 0.45–1.80 μg/ml and activation decreased at higher and lower trypsin concentrations. Microscopic observation showed that the dissociation rate of eupyrene sperm bundles by the g. prostatica homogenate corresponded to that by 0.45–9.0 μg/ml of trypsin. An autolysate of the g. prostatica and digests of seminal fluid with the g. prostatica homogenate or trypsin did not activate apyrene sperm. Of 11 endopeptidase inhibitors tested, antipain, leupeptin, TLCK, TPCK and PMSF strongly inhibited sperm activation by the g. prostatica homogenate, suggesting that the activator is an endopeptidase of the wine protease type. The 6 exopeptidase inhibitors tested did not inhibit activation of apyrene spermatozoa and the dissociation of eupyrene sperm bundles are both caused by the same factor, initiatorin, an endopeptidase of the serine protease type present in the prostatic secretion.