Induction of the Acrosome Reaction of Hemicentrotus pulcherrimus Spermatozoa by the Egg Jelly Molecules, Fucose-Rich Glycoconjugate and Spem-Activating Peptide I |
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Authors: | Masaaki Yamaguchi Masanori Kurita Norio Suzuki |
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Affiliation: | Noto Marine Laboratory, Kanazawa University, Ogi, Uchiura, Ishikawa 927-05, Japan |
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Abstract: | A fucose-rich glycoconjugate (FRG) was isolated from egg jelly of the sea urchin Hemicentrotus pulcherrimus by gel filtration. FRG induced the acrosome reaction in H. pulcherrimus spermatozoa in a concentration-dependent manner, although it showed about half the activity of the original unfractionated jelly. Synthetic sperm-activating peptide I (SAP-I: Gly-Phe-Asp-Leu-Asn-Gly-Gly-Gly-Val-Gly) increased the rate of the acrosome reaction induced by FRG; the maximal rate of the acrosome reaction with FRG and SAP-I being that of the unfractionated jelly. The half-maximal increase in induction of the acrosome reaction by SAP-I with FRG occurred at 4 × 10−10 M SAP-I, which was almost the same concentration inducing half-maximal stimulation of sperm respiration. Pronase digestion of FRG resulted in an 50% decrease in induction of the acrosome reaction and also in the elevation of cAMP in sperm. Some reagents (monensin and 3-isobutyl-1-methylxanthine) which increase intracellular pH, Ca2+ and cyclic nucleotides also increased the rates of the acrosome reaction induced by FRG or pronase-digested FRG. However, the rates did not reach those with FRG or pronase-digested FRG with SAP-I. These results indicate that SAP-I promotes induction of the acrosome reaction by acting as a specific co-factor of FRG. |
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