Characterization and analysis of differentially expressed microRNAs in hircine ovaries during the follicular and luteal phases.

Ovarian activity, which is mainly controlled by follicle-stimulating hormone and luteinizing hormone, is vital to successful reproduction and maintaining reproductive efficiency in livestock. To determine if the regulation of follicular-luteal transition occurs at the post-transcriptional level in hircine ovaries, the expression patterns of small RNAs in the ovarian tissues of Anhui white goats in the follicular and luteal phases were analyzed using Solexa sequencing. In total, 1039 miRNAs were co-expressed in the two libraries, and 278 and 469 miRNAs were specifically expressed in the hircine ovaries during the follicular and luteal phases, respectively. A total of 43 potential novel miRNAs were predicted in the two libraries. GO annotation and KEGG pathway analysis were applied to analyze the target genes of all miRNAs predicted in the two libraries. The highly and differentially expressed miRNAs included miR-26-5p, miR-145-5p, miR-145, miR-145a-5p, miR-125a-5p, miR-320d, and miR-320c, which may participate in follicular-luteal transition. Five co-expressed miRNAs, of which 2 were differentially expressed between the two libraries, were randomly selected to validate the expression pattern using RT-PCR, and the results were consistent with the Solexa sequencing data. Our present results help to clarify the roles of miRNAs in the regulation of follicular-luteal transition in goat ovaries, which may further enhance the reproductive efficiency of commercially important animals in the future.