Purification of binder of sperm protein 1 (BSP1) and its effects on bovine in vitro embryo development after fertilization with ejaculated and epididymal sperm

The present study evaluated functional aspects of binder of sperm 1 (BSP1) in the bovine species. In a first experiment, cumulus-oocyte complexes (n = 1274) were incubated with frozen-thawed ejaculated sperm (18 hours) in Fert-TALP medium containing: heparin, 10, 20, or 40 mu g/mL BSPI. Heparin followed by gelatin affinity chromatography was used for purification of BSP1 from bovine seminal vesicle fluid. With ejaculated sperm, cleavage rates were similar when Fert-TALP medium was incubated with heparin (74.1 +/- 2.7%), 10 mu g/mL BSP1 (77.8 +/- 3.1%), or 20 mu g/mL BSPI (74 +/- 2.0%). Day-7 blastocyst rates were equivalent after incubations with heparin (40.8 +/- 5.0%) and 10 mu g/inL BSPI (34.1 +/- 4.4%), but reduced after 20 mu z/mL BSPI (22.4 +/- 2.9%) and 40 mu g/mL BSPI (19.3 +/- 4.1%; P < 0.05). In the second experiment, cumulus-oocyte complexes (n = 1213) were incubated with frozen-thawed cauda epididymal sperm (18 hours) in Fert-TALP medium containing: no heparin, heparin, 10, 20, or 40 mu g/mL. Cleavage and blastocyst rates were similar after treatments with heparin (68.5 +/- 1.3% and 24.7 +/- 3.2%, respectively) or without heparin (65.5 +/- 1.8% and 273 +/- 1.6%, respectively). Cleavage was higher after treatment with any BSP1 concentrations (74.2 +/- 2.7%-79.0 +/- 1.1%) than without heparin (P < 0.05). Also, cleavage was better after Fert-TALP medium incubation with 40 mu g/mL BSP1 (79.0 +/- 1.1%) than with heparin (68.5 1.3%; P < 0.05). Embryo development was higher (P < 0.05) after treatment with 20 mu g/mL BSPI (35.6 +/- 2.5%) and 40 mu g/mL (41.1 +/- 2%) than after incubations with heparin (24.7 +/- 3.2%) or without heparin (27.3 +/- 1.6%). Interestingly, BSPI did not cause reductions in blastocyst rates after fertilization with epididymal sperm, as observed with ejaculated sperm. On the basis of immunocytochemistiy, there was BSP1 binding to frozen-thawed ejaculated but not to epididymal sperm. Also, anti-BSP1 reaction remained on ejaculated sperm (as expected) and appeared on epididymal sperm after incubation with purified BSPI. Acrosome reaction of ejaculated and epididymal sperm was induced after incubation with purified BSPI as well, indicating an effect of BSP1 on capacitation. In conclusion, purified BSPI from bull seminal vesicles was able to bind to