Identification and Profiling of MicroRNAs in the Embryonic Breast Muscle of Pekin Duck

MicroRNAs (miRNAs) regulate gene expression by fully or partially binding to complementary sequences and play important roles in skeletal muscle development. However, the roles of miRNAs in embryonic breast muscle of duck are unclear. In this study, we analyzed the miRNAs profiling in embryonic breast muscle of Pekin duck at E13 (the 13th day of hatching), E19, and E27 by high-throughput sequencing. A total of 382 miRNAs including 359 preciously identified miRNAs 23 novel miRNA candidates were obtained. The nucleotide bias analysis of identified miRNAs showed that the miRNAs in Pekin duck was high conserved. The expression of identified miRNAs were significantly different between E13 and E19 as well as between E27 and E19. Fifteen identified miRNAs validated using stem-loop qRT-PCR can be divided into three groups: those with peak expression at E19, those with minimal expression at E19, and those with continuous increase from E11 to E27. Considering that E19 is the fastest growth stage of embryonic Pekin duck breast muscle, these three groups of miRNAs might be the potential promoters, the potential inhibitors, and the potential sustainer for breast muscle growth. Among the 23 novel miRNAs, novel-miRNA-8 and novel-miRNA-14 had maximal expression at some stages. The stem-loop qRT-PCR analysis of the two novel miRNAs and their two targets (MAP2K1 and PPARa) showed that the expression of novel-mir-8 and PPARa reached the lowest points at E19, while that of novel-mir-14 and MAP2K1 peaked at E19, suggesting novel-miRNA-8 and novel-miRNA-14 may be a potential inhibitor and a potential promoter for embryonic breast muscle development o