Selenium supplementation during invitro maturation enhances meiosis and developmental capacity of yak oocytes.

Abstract

The objectives of the present study were to investigate the effects of selenium (Se) supplementation during invitro maturation (IVM) on the developmental capacity of yak (Bos grunniens) oocytes. Nuclear maturation, DNA integrity, glutathione peroxidase (GSH-Px) activity, subsequent embryonic development, and gene expression after invitro fertilization (IVF) were evaluated. The Se concentrations in yak plasma and follicular fluid were 0.142 and 0.069μg/mL, respectively. The DNA damage in cumulus cells decreased significantly with 2 and 4μg/mL supplementation of sodium selenite to IVM medium (P<0.05). Total GSH-Px activity in oocytes increased in all Se supplementation groups, and the 2 and 4μg/mL groups were significantly higher than the control group (0μg/mL). However, the cleavage rate was not significantly different after Se supplementation (P>0.05). The IVF blastocyst formation rates of 0, 1 and 4μg/mL sodium selenite groups were 47.7%, 51.2% and 58.9%, respectively. The 2μg/mL sodium selenite group had the highest blastocyst formation rate (60.5%). Gene expression analysis revealed that the quantity of transcripts associated with selenoprotein and protein synthesis were high in the 2 and 4μg/mL groups. In conclusion, both GSH-Px activity of oocytes and DNA integrity of cumulus cells significantly increased with supplemental Se during oocyte IVM. Considering that embryonic development is responsive to Se supplementation, we inferred that appropriate Se concentrations during IVM were beneficial for yak oocyte maturation and subsequent development.