Yasser H.A. Saber1*, Sally Ibrahim1, Karima Gh. M. Mahmoud1, Wahid M. Ahmed1, Refaat S.A. Ragab2, Adel A.M. Seida2*

Abstract | Accumulation of lipid droplets is a main obstacle for cryopreservation and low survivability of embryos. This investigation aimed to study the effect of phenazine ethosulfate (PES) supplementation in culture media on the selected miRNAs (miR-205, miR-26a-5p, and let-7b) and their target genes (OCT4, DNMT, CASP3, ATF6, ATP5ME, and ELOVL5), during bovine embryo production. Therefore, a group of two-day bovine embryos was cultured in a medium with lipid-reducing agent, PES (0.3 mM). Another group of embryos without PES was served as a control. Embryos were vitrified and morphologically examined after warming. The viability also was evaluated by culturing for 24 h. After evaluation, embryos were classified into a good or a poor. Afterwards, embryos (blastocyst and morula) were kept at -80°C for RNA extraction and qRT-PCR of the selected miRNAs and their targets. Results revealed that the rate of morula was higher (P<0.01) in treated compared to control groups. After vitrifications, the percentage of good quality embryos increased in treated groups than control groups. Additionally, the rate of dead embryos was higher in control groups. The Let-7b and miR-205 were significantly over-expressed in the treated good as well as poor embryos compared to control (untreated) good and poor embryos, respectively. However, miR-26 was suppressed in the treated good and poor embryos compared to control (untreated) embryos, respectively. Both of OCT4 and DNMT1 transcripts up-regulated in the treated (good and poor) embryos compared to control groups. The ELOVL5 gene decreased in the treated (good and poor) embryos, compared to control ones. In conclusion, PES supplementation reduced lipid droplets, and improved cryotolerance of the blastocysts via modulation the expression pattern of miRNAs and their target genes.

Keywords | miRNA, Bovine, Phenazine ethosulfate, Vitrifications, Embryos quality