Effect of the estrous cycle on zinc transporter expression in bovine cumulus-oocyte complexes and oviduct epithelial cells.

During the luteal and follicular phases of the estrous cycle, cumulus-oocyte complexes (COC) and oviduct epithelial cells (OEC) undergo notable physiological and morphological changes. Maintaining proper zinc (Zn) homeostasis is crucial in both somatic and germinal mammalian cells. This study aimed to assess the impact of the estrous phase (luteal or follicular) on Zn transporter expression in bovine COC and OEC (BOEC). The expression of Zn transporters Slc39a6 (ZIP6), Slc39a8 (ZIP8), Slc39a14 (ZIP14), Slc30a3 (ZnT3), Slc30a7 (ZnT7), and Slc30a9 (ZnT9) was analyzed in COC and BOEC from cows during the luteal or follicular phases. Gene expression of ZIP6, ZIP14, and ZnT9 was quantified in COC and BOEC. The gene expression in the remaining transporters could not be quantified due to low mRNA levels (ZIP8 and ZnT3 in COC and BOEC; ZnT7 in BOEC) or absence of expression (ZnT7 in COC). In COC, the relative expression (RE) of all three transporters was higher in the luteal phase compared to the follicular phase (P ≤ 0.05). In BOEC, the luteal phase increased the RE of ZIP 6 (P ≤ 0.05), decreased the RE of ZnT9 (P ≤ 0.05), and did not modify the RE of ZIP14 (P > 0.05) compared to the follicular phase. In conclusion, the study reveals differences in the gene expression of ZIP6, ZIP14, and ZnT9 according to the estrous cycle phase in ex vivo samples of bovine COC and OEC.

Trace mineral mixture supplemented to in vitro maturation medium improves subsequent embryo development and embryo quality in cattle.

Trace minerals participate in reproductive processes and are crucial for oocyte maturation. The objective of the present study was to investigate the effect of combined supplementation with copper (Cu), manganese (Mn), selenium (Se) and zinc (Zn) during bovine in vitro maturation (IVM) on subsequent embryo development and quality. The IVM medium was supplemented as follows: a) Control (no mineral supplementation); b) MScz (6 ng/mL Mn + 100 ng/mL Se + 200 ng/mL Cu + 400 ng/mL Zn); c) MScZ (6 ng/mL Mn + 100 ng/mL Se + 200 ng/mL Cu + 1200 ng/mL Zn); d) MSCz (6 ng/mL Mn + 100 ng/mL Se + 600 ng/mL Cu + 400 ng/mL Zn). Supplementation with MScz and MSCz produced more blastocysts compared with the control. Total blastocyst cell number was higher when minerals were added at any combination. Day-8 blastocysts derived from oocytes treated with minerals had lower intracellular reactive oxygen species concentration and lipid content than the control. In conclusion, combined supplementation with Cu, Mn, Se and Zn during bovine oocyte IVM increased in vitro production performance, improving embryo developmental ability and quality.