Sex-biased miRNAs of yellow catfish (Pelteobagrus fulvidraco) and their potential role in reproductive development

Yellow catfish has been used as an important model to investigate sex differentiation and gonad development. miRNAs have been reported to play an important role in reproduction system. In this study, we conducted RNA-sequencing based miRNAs analysis of yellow catfish gonads at three different ages. We have totally identified 300 miRNAs. Of these miRNAs, 242 miRNAs were conserved in miRBase, while the other 58 miRNAs were firstly identified in our study. A total of 37, 72 and 87 miRNAs were identified as sexually differentially expressed miRNAs in one-year, two-year and three-year old yellow catfish, respectively. Eleven miRNAs appeared to be stably male-biased expressed in three ages, including miR-9-3p, miR-103b-3p, miR-7b, miR-205a-5p, miR-200b-3p, miR-200a, miR-150-3p, let-7i-5p, let-7g-5p, let-7h-5p and miR-30d-5p. Two novel miRNAs, novel_77 and novel_147, firstly identified in our study, had significantly up-regulated in ovaries through three different ages, which may be new biomarkers for female gonad development. KEGG pathway annotation and enrichment analysis further illustrated their important roles in several reproductive pathways. Seven most significantly expressed miRNAs were verified by qPCR. Our work identified a set of sex-biased miRNAs that might be potential regulatory factors in gonad development of yellow catfish, which provides new insight to further understand the role of miRNAs in sex determination and differentiation of this economically valuable species.