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

EFFECT OF THE OVIDUCT ON BOVINE SPERM CAPACITATION AND PROTEIN TYROSINE PHOSPHORYLATION.

Galantino-Homer, Hannah^1,2, Megee, Susan¹, Killian, Gary³, Kopf, Gregory², Dobrinski, Ina¹, ^{1 2 3}

ABSTRACT- Sperm capacitation is defined as the maturational changes that render a spermatozoon competent to participate in fertilization. To date, information on capacitation mostly derives from in vitro studies, but sperm are exposed to specific and varied environments within the female reproductive tract during in vivo capacitation. Previous studies have shown that binding to the oviductal epithelium prolongs sperm viability and delays capacitation while non-luteal oviductal fluid stimulates sperm capacitation, but there is little information regarding the molecular mechanisms underlying these effects. The objectives of this study were to examine the effects of oviductal epithelial apical membrane vesicles (OAMV) on bovine sperm viability and capacitation and to evaluate the effects of OAMV and non-luteal oviductal fluid on signaling events leading to capacitation. We report that incubation of cryopreserved bovine spermatozoa with bovine OAMV is effective in maintaining sperm viability over a 12 h incubation period and retards capacitation, as assessed by chlortetracycline staining, when compared to controls. Following a 4 h incubation under conditions that support capacitation, ejaculated bovine sperm incubated in the presence of 10 g/ml heparin display an increase in protein tyrosine phosphorylation, as detected by immunoblotting. OAMV inhibits this increase in protein tyrosine phosphorylation. In contast, sperm incubated with bovine non-luteal oviductal fluid display an increase in protein tyrosine phosphorylation. Similar results were obtained in at least three experiments using sperm from a minimum of two different bulls. It is likely that the effects of OAMV and non-luteal oviductal fluid on bovine sperm capacitation are mediated, at least in part, via modulation of signaling pathways leading to protein tyrosine phosphorylation. These studies are the first to explore the effect of these bovine female reproductive tract components on sperm intracellular signaling events.

KEY WORDS: sperm, capacitation, oviduct, signaling