Immunolocalization and Possible Functional Role of PSP‐I/PSP‐II Heterodimer in Highly Extended Boar Spermatozoa

Abstract

PSP-I/PSP-II heterodimer is a major protein of boar seminal plasma which is able to preserve, in vitro, the viability, motility, and mitochondrial activity of highly extended boar spermatozoa for at least 5 hours. However, little is known about the binding pattern of the heterodimer to the sperm plasma membrane and its eventual relation with the maintenance of the sperm functionality. The present study investigated the effect of exposing highly extended boar spermatozoa (1 million/mL) to 1.5 mg/mL of PSP-I/ PSP-II for 0.5, 5, and 10 hours at 38uC on sperm characteristics and the changes in PSP-I/PSP-II localization as a result of both the addition of PSP-I/PSP-II to the extender and the incubation time. Exposure of the spermatozoa to PSP-I/PSP-II preserved sperm viability, motility, and mitochondrial activity when compared to nonexposed spermatozoa. This protective effect lasted for 10 hours (P , .05). After immunolabeling of highly extended semen with rabbit monospecific polyclonal antibody against PSP-I/PSP-II, the percentage of immunopositive spermatozoa declines over time from 71% (0.5 hours) to 49% (10 hours). However, more than 80% of spermatozoa remained labeled during the 10-hour incubation period if PSP-I/PSP-II was added. Scanning electron microscopy revealed 4 different binding patterns. The heterodimer was mainly localized to the acrosomal area, being redistributed to the postacrosomal area or lost during in vitro incubation. In conclusion, the protective effect of the heterodimer appears to be related to its adhesion to the acrosomal area, and the loss of this protective effect coincides with a stepwise redistribution of PSP-I/PSP-II during incubation.

Evaluation of bull semen for fertility-associated protein,in vitrocharacters and fertility

“…Caballero et al (2006) confirmed the protective effect role of fertility-associated PSP proteins by electron microscopic study and reported that these proteins were localized on the acrosomal and post-acrosomal regions of the sperm head and were distributed to other parts during incubation.…”

Remodelling of Lipid Rafts during In vitro Capacitation and Acrosome Reaction of Ram Spermatozoa

“…Furthermore, proteins from DRMs and non-DRMs are lost after capacitation and the acrosome reaction. These results are consistent with previous reports that describe the release of sperm membrane proteins during capacitation of bull [70], boar [71,72], rabbit [73] or ram [74] spermatozoa.…”

Effect of seminal plasma zinc–binding proteins on motility and membrane integrity of canine spermatozoa stored at 5°C

“…There are several proteins with sperm-coating and zinc-binding properties, which also have a positive impact on the parameters of the stored spermatozoa. The main boar seminal plasma zinc-binding spermadhesin -PSPI/PSPII, exerted positive effects on highly-diluted boar spermatozoa viability, motility and mitochondrial activity (7,10). ZnBPs of boar seminal plasma allowed preservation of a higher percentage of cells exhibiting linear motility and a higher percentage of intact acrosomes when stored at 4ºC (19).…”