Serum microRNAs in buffalo cows: Potential biomarkers of pregnancy.

MiRNAs (microRNA) constitute a large family of single-stranded, non-coding small RNAs. Although the functions and target genes of most miRNAs are still unknown, it has been well established that they are involved in embryogenesis, organogenesis and neonatal birth. In recent decades, interest in buffalo breeding has largely increased worldwide thus focusing the attention on this species as a dairy purpose animal. Problems related to long calving interval, late puberty and seasonal anestrus hamper reproductive efficiency in this species. Early pregnancy diagnosis is important to shorten the calving interval and increase lifetime production on dairy animals. MicroRNAs have recently emerged as key molecules in fertilization of several species even though in buffalo, few previous studies have investigated miRNAs. The aim of this research was to identify the best miRNA reference in serum among miR-191, miR-25-3p, SNORD44, and SNORD48. Consequently, assess the expression levels of miR-103, miR-200b, miR-301a, miR-423-5p, miR-375, miR-451 and miR-452 involved in buffalo progesterone-maturation oocyte and pregnancy. Interestingly, we found that all the miRNAs analyzed at 40days after artificial insemination were differentially expressed among pregnant and non-pregnant buffalo. Our research may be a first step for gain further insight in the biological function of circulating miRNAs in this species.