PARENT SESSION
PLATFORM SESSION 16. FEMALE REPRODUCTIVE TRACT II

Tuesday, August 3, 2004
4:30 PM–6:30 PM
Buchanan A202
Chair: William Okulicz Co-Chair: Julie Hastings

(562) BOVINE SEMINAL PLASMA PROTEINS A3 AND 30kDa SHARE A FUNCTIONAL ROLE WITH PDC-109 TO MEDIATE SPERM BINDING TO OVIDUCTAL EPITHELIUM.

Gwathmey, TanYa¹, Ignotz, George¹, Manjunath, Puttaswamy², Suarez, Susan¹, ¹ Cornell University, Ithaca, NY² University of Montreal and Guy-Bernier Research Center, Montreal, Quebec, Canada

ABSTRACT- Upon ejaculation, bull sperm are exposed to the secretions of the seminal vesicles, prostate, and accessory glands and become coated with various proteins, including a family of proteins called BSPs (bovine seminal plasma proteins), comprising BSP A1/A2, BSP A3 and BSP 30kDa. Previously, we demonstrated that BSP A1/A2 (PDC-109) enables epididymal sperm to bind to explants of oviductal epithelium, and competitively inhibits binding of ejaculated sperm. Because the BSPs share significant sequence homology, we investigated if BSP A3 and BSP 30 kDa were also effective at mediating binding of sperm to oviductal epithelium. Epididymal sperm were obtained from caudal epididymides, washed twice by centrifugation in TALP medium, incubated with 250 g/ml BSP A1/A2 or BSP A3, 500 g/ml BSP 30 kDa (representing equimolar concentrations) or buffer for 20 min, then washed by centrifugation and dilution to remove excess unbound protein. Sperm were then added to oviductal epithelial explants and incubated at 39^oC and 5%CO₂ to allow binding. After 20 min, explants were rinsed to remove unbound sperm and binding density (no. sperm bound/(0.1mm),² explant surface) was determined by assessing video-recordings and employing NIH Image to determine surface area. Both BSP A3 (23.6 +/- 4.8) and BSP 30kDa (16.0 +/- 4.3) significantly increased binding density above control values (5.9 +/- 1.6; mean +/- SEM; N=5, P<0.05). This effect was not observed when a protein of similar size and charge (myosin light chain) was added to sperm. We next examined whether BSPs could competitively inhibit the binding of ejaculated sperm to oviductal epithelium. Ejaculated sperm were washed thrice in TALP by centrifugation and added to oviductal explants pre-treated with 250 g/ml BSP A1/A2 or BSP A3, 500 g/ml BSP 30 or buffer. After 20 min, sperm/explant complexes were rinsed in TALP to remove unbound sperm, then video-recorded to assess sperm binding density. BSP A3 (29 +/- 4%) and BSP 30kDa (43 +/- 11%) were as effective as PDC-109 (39 +/- 8%)(% of control; N=6, P<0.01) in reducing binding density. These results indicate that BSP A3 and BSP 30kDa can also mediate sperm binding to oviductal epithelium and that all three BSPs play a role in formation of the oviductal sperm reservoir. USDA 97-35203-4734.

KEY WORDS: female reproductive tract, oviduct, sperm, epididymis