Sperm miRNAs - potential mediators of bull age and early embryo development

To identify if the patterns of spermatic small non-coding RNAs (sncRNAs) are affected by paternal age and/or impact early embryogenesis, we generated sncRNAs libraries of sperm collected from same bulls at 10, 12, and 16 months of age, using 16 months as control for differential expression and functional analysis. miRNAs present in measurable quantity in oocytes were excluded. Of the remaining miRNAs, ten sperm-borne miRNAs were significantly differentially expressed in younger bulls (four in the 10 vs 16 months contrast and six in the 12 vs 16 months contrast). Targets of miRNAs were identified and compared to the transcriptomic database of two-cell embryos, to genes related to two-cell competence, and to the transcriptomic database of blastocysts. Ingenuity pathway analysis of the targets of these miRNAs suggested potential influence on the developmental competence of two-cell embryos and on metabolism and protein synthesis in blastocysts. The results showed that miRNA patterns in sperm are affected by the age of the bull and may mediate the effects of paternal age on early embryonic development. Overall design: sncRNAs profile of four bulls at 10, 12, and 16 months old were generated.