Thesis (Ph.D.) - Cairo University - Faculty of Veterinary Medicine - Department of Theriogenology

In vitro embryo production (IVEP) is considered as one of the most important technologies in cattle industry due to production of superior quality embryos with high developmental competence that use at low costs in embryo transfer programs. So, improvement of in vitro culture systems are the most critical and essential step to keep on this biotechnology. Hence, the current experiments were designed. Experiment 1, aimed to (I) 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 left as a control. Embryos were vitrified and morphologically examined after warming and the viability was evaluated by culturing for 24 h. After evaluation, embryos were classified as good or poor. Afterwards, embryos (blastocyst and morula) were kept at -80{u00B0}C for RNA extraction and qRT-PCR of 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 than control groups. Additionally, the rate of dead embryos was high 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 OCT4and DNMT1 transcripts up-regulated in the treated (good& poor) embryos compared to control groups

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