PARENT SESSION
SLIDE SESSION 16: FERTILIZATION
Chairs: William Breed, Nuch Tanphaichitr, Becky Sortini (Trainee)
Univ Ottawa-UCU Auditorium
1:30 PM-3:30 PM

LOCALIZATION OF DRKD SPERM PROTEIN ON BOAR SPERM.

Sartini, Becky¹, Berger, Trish ¹, ¹

ABSTRACT- A boar 39 kD sperm plasma membrane protein (DRKD based upon its N-terminal sequence) has affinity for isolated porcine oocyte plasma membrane on Western ligand blots and is potentially involved in gamete membrane interaction during porcine fertilization. In this study, polyclonal antibody against DRKD was used to localize the DRKD protein on freshly ejaculated and capacitated boar sperm. Sperm were washed on a Percoll gradient; capacitated sperm were incubated for 4 hours in Tris-buffered medium with 5 mg/ml BSA at 39°C with 5% CO₂ in air. All sperm were fixed with 2% paraformaldehyde. Anti-DRKD bound to the whole head and tail of freshly ejaculated sperm (100%) from four boars. On capacitated sperm, anti-DRKD redistributed to the postacrosomal region and tail (22%±8%; p<0.01) and percentage of sperm with whole head and tail staining decreased (74%±10%; p< 0.01). The percentage of capacitated sperm with anti-DRKD postacrosomal staining was not significantly correlated with spontaneous acrosome reaction rate. Preimmune serum did not exhibit staining for any treatments. We also observed a seasonal pattern of anti-DRKD localization on boar sperm. In sperm collected during the summer months, anti-DRKD was localized to the anterior head of 4 hour capacitated sperm (45%) on 8 ejaculates from two boars. Sperm from these same two boars (9 ejaculates) displayed the postacrosomal region anti-DRKD staining pattern as described above during the winter months before and after the summer collection period. We speculate that the change in anti-DRKD staining pattern results from the reduced fertility of boar sperm during the summer months. We have demonstrated that the boar DRKD sperm protein is in the correct position to mediate boar sperm interaction with porcine oocyte plasma membrane. (Supported in part by NRICGP 99-02240 and NIH Fertilization Training Grant)

KEY WORDS: sperm plasma membrane, oocyte plasma membrane, porcine fertilization