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Before fertilization, sperm bind to epithelial cells of the oviduct isthmus to form a reservoir that regulates sperm viability and capacitation. The sperm reservoir maintains optimum fertility in species, like swine, in which semen deposition and ovulation may not be well synchronized. We demonstrated previously that porcine sperm bind to two oviductal glycan motifs, a biantennary 6-sialylated N-acetyllactosamine (bi-SiaLN) oligosaccharide and 3-O-sulfated Lewis X trisaccharide (suLeX). Here, we assessed the ability of these glycans to regulate sperm Ca2+ influx, capacitation and affect sperm lifespan. After 24 h, the viability of sperm bound to immobilized bi-SiaLN and suLeX was higher (46% and 41% respectively) compared to viability of free-swimming sperm (10–12%). Ca2+ is a central regulator of sperm function so we assessed whether oviduct glycans could affect the Ca2+ influx that occurs during capacitation. Using a fluorescent intracellular Ca2+ probe, we observed that both oviduct glycans suppressed the Ca2+ increase that occurs during capacitation. Thus, specific oviduct glycans can regulate intracellular Ca2+. Because the increase in intracellular Ca2+ was suppressed by oviduct glycans, we examined whether glycans affected capacitation, as determined by protein tyrosine phosphorylation and the ability to undergo a Ca2+ ionophore-induced acrosome reaction. We found no discernable suppression of capacitation in sperm bound to oviduct glycans. We also detected no effect of oviduct glycans on sperm motility during capacitation. In summary, LeX and bi-SiaLN glycan motifs found on oviduct oligosaccharides suppress the Ca2+ influx that occurs during capacitation and extend sperm lifespan but do not affect sperm capacitation or motility. [ABSTRACT FROM AUTHOR]

The present study aimed to evaluate the effect of supplementing epidermal growth factor (EGF), insulin-like growth factor-I (IGF-I), fetal bovine serum (FBS), and bovine serum albumin (BSA) in different combinations in a maturation medium (MM) comprising TCM-199 + 5 μg/mL 17-β estradiol + 5 μg/mL ovine-luteinizing hormone (oLH) + 5 μg/mL pure follicle-stimulating hormone (pFSH) + 100 μM/mL cysteamine containing the best concentration of leptin among 10/20/25/30 ng/mL on in vitro maturation (IVM) and subsequent vitrification of matured goat oocytes. The IVM of oocytes was carried out in a CO2 incubator for 27 h at 38.5 °C. The percentage of oocytes with cumulus expansion and polar body extrusion was found to be highest in 25 ng/mL leptin at 47.37% and 15.63%; rates of 66.67% and 28.57% were obtained when supplemented with 50 ng/mL IGF-I + 10 ng/mL EGF in medium containing 25 ng/mL leptin as compared to the other media. The in vitro matured oocytes were vitrified in 5 M ethylene glycol + 5 M propylene glycol with 0.5 M sucrose in TCM-199 + 20% FBS using liquid nitrogen. The highest percentage of morphologically intact in vitro matured oocytes following vitrification was obtained in medium containing 25 ng/mL leptin (89.29%). It was concluded that addition of IGF-I + EGF with 25 ng/mL leptin in MM yielded a higher rate of maturation of oocytes, and supplementation of 25 ng/mL leptin in MM resulted in a higher rate of morphologically intact vitrified oocytes, indicating the efficiency of leptin for cryotolerance. [ABSTRACT FROM AUTHOR]