Sperm capacitation of the shrimp Litopenaeus vannamei

摘要

Litopenaeus vannamei is one of the most important species of farmed shrimp. The females have an ‘open’ thelycum. Mating is accomplished by attaching the male spermatophore onto the surface of the thelycum 4–6?h before spawning. During this period, sperm may have to undergo morphological changes associated with a capacitation process that has been described for other shrimp species. The objective of this research was to extend research on sperm capacitation in L. vannamei by ultrastructural and biochemical means. The sperm of L. vannamei were divided into those freshly prepared from the spermatophore (S-sperm), extracted from the male gonopores, and those extracted from the female thelycum (T-sperm). Under transmission electron microscopy, ultrastructural differences were detected between the S- and the T-sperm in the nuclear material, the filamentous meshwork and the cytoplasmic particles. Under scanning electron microscopy, the difference was observed in the cap and spike regions. Immunofluorescence using confocal microscopy to detect tyrosine phosphorylated proteins revealed different distribution patterns between S- and T-sperm. The location of phosphorylation activity changed from the spike in S-sperm, to the filamentous meshwork in the T-sperm. These morphological and biochemical changes confirm that capacitation of L. vannamei sperm takes place following mating.