Ultrastructure and Protein Composition Changes during Acrosome Reaction in the Sperm of Chinese Shrimp, Fenneropenaeus Chinensis

Egg water was used to induce acrosome reaction in mature sperm of Fenneropenaeus chinensis .Transmission electron microscope and SDS PAGE were used to study the ultrastructure and protein changes of the sperm in F.chinensis ,which has undergone acrosome reaction.The results demonstrated that the sperms from female thelycum could be induced acrosome reaction in vitro by egg water,which was a kind of egg jelly released from oocyte into seawater during oocyte activation.More than fifty percent of sperm finished acrosome reaction during the first 30 min, in vitro .The whole event consists of the retraction of the spike and acrosome exocytosis.Spike was retracted and fused to acrosome cap followed by the release of acrosome granules.When the original egg water was diluted 5 and 10 times,The diluted egg water also have the ability to induce sperm acrosome reaction,but the acrosome reaction rate is much lower than that of the original egg water in the same time.Capillary zone electrophoresis was used to detect the biochemical components of egg water.Egg water was composed of two different components,which were also demonstrated by SDS PAGE.The molecular weights of the two kinds of egg jellies are both about 200kDa.Gelatin substrate SDS PAGE results did not show any hydrolytic enzyme activity in egg water.After acrosome reaction,many sorts of proteins in sperm are degraded.When the reacted sperms were examined with gelatin substrate SDS PAGE,there were six major peptide bands with hydrolytic enzyme activity were detected.Their molecular weights are 200kDa,130 kDa,66 kDa,53 kDa,48 kDa and 41 kDa respectively.These hydrolases cannot be detected in the sperms before acrosome reaction.The acrosome reaction of Chinese shrimp, F.chinensis is much different to that of the sperm in the shrimp, Sicyonia ingentis ,which the acrosome reaction was clearly studied.There is not filament formation during the acrosome reaction in Chinese shrimp.The time of exocytosis in the sperm of Chinese shrimp is also much longer than that of the sperm of Sicyonia ingentis .