Influence of Porcine Spermadhesins on the Susceptibility of Boar Spermatozoa to High Dilution1

Abstract

The effect of heparin-binding and non-heparin-binding spermadhesins on the viability, motility, and mitochondrial activity of boar spermatozoa at the high dilution (300,000 sperm/ml) to which sperm are exposed during the process of sex sorting by flow cytometry was investigated. Incubation of spermatozoa with heparin-binding spermadhesins caused a time- and dose-dependent decrease in the percentage of functional spermatozoa. The percentage of viable spermatozoa incubated at 38 degrees C with heparin-binding spermadhesins diluted in PBS (1 mg/ml) dropped from 75% (0.5 h) to 4% (5 h), whereas the percentage of viable spermatozoa incubated in PBS without proteins (control) decreased from 85% (0.5 h) to 19% (5 h). Addition of non-heparin-binding PSP-I/PSP-II spermadhesin to the PBS resulted in a concentration-dependent increment of the percentage of viable cells (65% after 5-h incubation), with maximum effect at 1.5 mg/ml. The heparin-binding spermadhesins totally suppressed sperm motility and mitochondrial activity after 5 h of incubation. The same parameters of sperm incubated in the presence of 1.5 mg/ml of PSP-I/PSP-II were 50% and 58%, respectively, and the percentages of control sperm displaying motility and mitochondrial activity were 21% and 26%, respectively. Moreover, the viability, motility, and mitochondrial activity all decreased on incubation of spermatozoa with mixtures of PSP-I/PSP-II and heparin-binding spermadhesins as the concentration of the latter increased. We conclude that PSP-I/PSP-II and the heparin-binding spermadhesins exert antagonistic effects on the functionality of highly diluted boar spermatozoa. The finding that PSP-I/PSP-II contributes to maintaining sperm with high viability, motility, and mitochondrial activity for at least 5 h at physiological temperature points to its potential use as an additive for sperm preservation, specifically of highly diluted, flow-sorted spermatozoa for sex preselection.

Seminal Plasma Proteins: What Role Do They Play?

“…33 Detection of AWN epitopes on boar spermatozoa bound in vivo to the ZP strongly suggests that the protein mediates sperm-ZP interaction. 34 While HBPs do not seem to promote sperm survival, at least in vitro, 35 the non-heparin-binding PSP-I and PSP-II, 36,37 which accounts for >50% of all SP proteins and forms a glycosylated heterodimer, 38 binds to the sperm surface and displays protective action on highly extended and processed spermatozoa. 39,40 The PSPs depict, moreover, clear immunostimulatory activities in vitro and in vivo, presumably in relation to specific cytokines.…”

Sperm surface changes and physiological consequences induced by sperm handling and storage

“…Moreover, the heparin-binding BSP protein, pB1, has also been shown to stimulate capacitation of epididymal boar spermatozoa by inducing cholesterol and phospholipid efflux from the sperm membrane (Lusignan et al 2007), which has been extensively documented with bull BSP proteins. Incubation of highly diluted boar spermatozoa (extended to a level that mimicked sex-sorting: 0.3-1!10 6 sperm/ml) with heparin-binding proteins was detrimental to in vitro sperm function (Centurion et al 2003), causing a timeand dose-dependent decrease in the motility, viability and mitochondrial integrity of spermatozoa. Nonheparin-binding proteins showed the opposite effect ) and the protective effect was largely afforded by the PSP-I/PSP-II heterodimer.…”

Effect of boar ejaculate fraction, extender type and time of storage on quality of spermatozoa

“…The PSP-I/PSP-II heterodimer is present in all SP fractions, although its concentration increases gradually with a dose of the heparin-binding spermadhesins proteins and the total proteins in the post-sperm-rich fractions. Centurion et al (2003) demonstrated that sperm viability and motility are determined by the presence of the heparin-binding and non-heparin-binding spermadhesins in the incubation mixture. Thus, we can assume that differences between F1 and F2 regarding the sperm quality resulted from the presence of these specific proteins and their concentration in the analyzed portion of semen.…”