Identification of microRNAs associated with sexual maturity in rainbow trout brain and testis through small RNA deep sequencing.

MicroRNAs are ubiquitous, short, non-coding RNA molecules that function as post-transcriptional regulators of gene expression in a variety of biological processes. In order to further our understanding of the microRNA hierarchy in the reproductive axis of male teleosts, four small RNA libraries were constructed, and sequenced from the testis and brain of sexually mature adults and immature juvenile rainbow trout (Oncorhynchus mykiss) using Illumina small-RNA deep sequencing. We obtained 56,632,987; 39,870,661; 82,454,370; and 53,143,465 high-quality, filtered reads for immature testis, mature testis, immature brain, and mature brain, respectively. Among the libraries, 433 known mature piscine miRNAs were identified, with 124 and 116 significantly differentially expressed miRNAs found between sexually immature/mature testes and immature/mature brain tissues, respectively. Among these differentially expressed miRNAs, miR-129, -130c, -135b, -140, -146a, -192, -199a, -16, and, -19b showed higher abundance in the testis whereas miR-10b, -183, -199, -375, -1937, and miR-nov210 were more abundant in the brain. In silico target prediction of these differentially expressed miRNAs suggested their putative roles in the sexual maturation of male rainbow trout.