Protein factors of capacitation and decapacitation in canine seminal plasma

The aim of the present study was to determine the proteins in canine seminal plasma with direct effect on specific sperm parameters during fertilisation. The influence of seminal plasma proteins was focused on three processes: capacitation, hyperactivation and decapacitation. Size exclusion chromatographic fractional separation of proteins from seminal plasma based on their molecular weights was performed. In addition, two-dimensional electrophoresis of two seminal protein fractions was done. The effect of protein molecules on the motion and kinetic parameters of the male gametes in in vitro conditions was monitored by computer-assisted sperm analysis. The activity of alkaline phosphatase, creatine kinase and alanine aminotransferase in whole seminal plasma and each chromatography fraction was measured spectrophotometrically using the BA-88A semi-automatic chemistry analyzer. The protein fractions with different molecular weights affected the in vitro motility and kinetic characteristics (curvilinear velocity, straightness, linearity and amplitude of lateral head displacement) of spermatozoa, leading to hyperactivation or initiating decapacitation kinetics changes. The detailed study of the seminal plasma proteome would add fundamental information about the processes associated with physiological changes occurring in spermatozoa before fertilisation. The study of the canine seminal plasma proteome could add relevant information about its effects on the fertilising ability of the male gametes and the changes occurring in them before fertilisation.