My PhD project addressed the paternal and maternal contribution associated with correct early embryonic development, focusing on microRNAs (miRNAs, short non-coding RNAs regulating gene expression at post-transcriptional level) involved in controlling reproductive function in cattle. To this end, next generation sequencing (NGS) methods and bioinformatic analysis pipelines were set up and validated using low quantities of starting materials, e.g. blastocysts and oocytes. The role of miRNAs carried by spermatozoa during early embryogenesis was investigated by assessing in vitro produced blastocysts from semen of bulls with high and low blastocyst rates. Moreover, follicular fluid and oocyte miRNAs were analyzed in order to unravel molecular mechanisms involved in poor fertility cows. In particular, a model based on low and high antral follicle count ovaries was used to study the influence of ovarian function on oocyte developmental competence. The results indicated that: 1) sperm miRNAs may impact embryo developmental competence affecting the expression of gene networks involved in several cellular processes including cell adhesion, communication and metabolism of the blastocyst; 2) the different oocyte quality is associated with a different miRNA blueprint in both follicular fluids and oocytes through the mis-regulation of biological processes critical for oocyte competence. In conclusion, these studies contributed to improve our knowledge on the function of miRNAs in the sperm, oocytes and pre-implantation embryos. Several miRNAs were identified as potential biomarkers of blastocyst and oocyte competences, which will be valuable to optimize Reproductive Biotechnologies
