Novel miRNA identification and comparative profiling of miRNA regulations revealed important pathways in Jinding duck ovaries by small RNA sequencing

Functional studies have revealed miRNAs play pivotal roles in ovulation and ovary development in mammalians. Jinding duck is an important commercial food in poultry industry, but little is known about the miRNA function in ducks. In this study, miRNA deep sequencing in the ovary tissues was carried out to compare the miRNA differential expression between before oviposition (BO) and after oviposition (AO) in Jinding duck. Overall, an average of 23,128,075 and 26,020,523 reads were identified in the BO and AO samples, respectively. Besides, 6739 miRNAs were identified through further mapping and analysis. In comparison with BO, 1570 miRNAs were significantly changed and a total of 2291 genes were predicted from 443 miRNAs through miRNA prediction database. In addition, GO and KEGG pathway analysis indicated that some basic cell metabolism pathways as well as the productive pathways such as MAPK signaling pathway, Gonadotropin-releasing hormone (GnRH) signaling pathway, TGF-beta signaling pathway had been significantly changed. Our results helped to replenish the duck miRNA database and illustrate the potential mechanism of miRNA function in duck ovary development and reproduction process.