Abstract
The aim of this study was to evaluate the effects of Ca 2+ , HCO 3 - and BSA on the in vitro capacitation-associated protein tyrosine phosphorylation, hyperactivation and acrosome reaction in guinea pig sperm. Caudal epididymal sperm were incubated in four different groups: modified TALP (Tyrode's albumin lactate pyruvate) or TALP without one of the medium constituents (Ca 2+ , HCO 3 - and BSA). After incubation for the required time (0 h, 0.5 h, 1 h, 3 h, 5 h, and 7 h), sperm were removed for further experiment. The capacitation effect was assessed by CTC (Chlortetracycline) staining. Western blotting and indirect immunofluorescence were used to analyze the level and localization of tyrosine phosphorylation. The results showed that guinea pig sperm underwent a time-dependent increase in protein tyrosine phosphorylation during the in vitro capacitation and the percentage of protein tyrosine phosphorylated sperm increased from 36% to 92% from the beginning of incubation to 7 h incubation. Also, there was a shift in the site of phosphotyrosine-specific fluorescence from the head of sperm to both the head and the flagellum. Moreover, an absence of Ca 2+ or HCO 3 - inhibited in vitro hyperactivation and acrosome reaction and decreased the phosphorylation of the proteins throughout the period of in vitro capacitation. However, an absence of BSA could not influence these processes if substituted by polyvinyl alcohol (PVA) in the medium.
Highlights
After leaving the testis, mammalian sperm are morphologically differentiated but are immotile and unable to fertilize
Effect of BSA on the capacitation of guinea pig sperm In order to find out whether these components of the medium are essential for sperm capacitation, guinea pig sperms were incubated in TALP devoid of BSA, and the percentage of sperms undergoing capacitation was measured
When guinea pig sperms were incubated in TALP, they showed a time-dependent increase in the percentage of capacitated sperm (Table 1)
Summary
Mammalian sperm are morphologically differentiated but are immotile and unable to fertilize. Capacitation involves several changes, occurring in both the sperm head and tail that lead to the release of the acrosomal content (called acrosome reaction, AR) (Yanagimachi, 1994) and to the acquisition of a distinct type of motility known as hyperactivation (Si and Okuno, 1999). Both events are essential for sperm penetration through the egg coatings.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
