Identification and analysis of novel microRNAs provide insights to reproductive capacity of the cultured Asian yellow pond turtle Mauremys mutica

Abstract

The crucial roles of miRNAs in regulating animal growth, development, and disease resistance have been extensively reported, but their roles in relation to the reproductive capacity of aquatic animals (numbers of eggs laid and hatchlings), especially reptiles, remain unclear. In this study, high-throughput sequencing technology was used to screen miRNAs related to reproductive capacity based on the construction of a cDNA library of ovaries from higher-fecundity (HF) and lower-fecundity (LF) M. mutica. The results showed that 15,767,494 (93.98%) and 14,137,621 (94.17%) high-quality reads were obtained from the HF and LF groups, respectively. We screened 131 miRNAs that were differentially expressed between the HF and LF groups, of which 78 were upregulated and 53 were downregulated compared with the M. mutica reference genome. GO and KEGG pathway enrichment analyses of the target genes of differentially expressed miRNAs revealed significant differences in the enrichment frequencies of genes associated with ATP binding and proteolysis between the HF and LF groups, while the tricarboxylic acid cycle, glucagon signaling pathway and vitamin B6 metabolic pathway were shown to potentially help determine reproductive capacity. Ten miRNAs were verified by qRT-PCR to confirm the reliability and accuracy of the sequencing results, and a miRNA-mRNA target gene interaction network was constructed. These results will further our understanding of the regulatory mechanism of miRNAs in regards to turtle reproductive capacity.