Comparative transcriptome analysis reveals the sexual dimorphic expression profiles of mRNAs and non-coding RNAs in the Asian yellow pond turtle (Meauremys mutica)

Noncoding RNAs (ncRNAs), including long ncRNAs (lncRNAs), circular RNAs (circRNAs) and microRNAs (miRNAs) have been extensively studied in biological processes such as disease development, cell proliferation but remained unclear in sex differentiation in organisms. In this study, the transcriptome profiles were comparatively analyzed between male and female gonads in Mauremys mutica. A total of 8237 differentially expressed genes (DEGs), 9573 DE lncRNAs, 84 DE circRNAs and 665 DE miRNAs were identified between male and female gonads. Through gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) of the DE RNAs, it was revealed that the DE mRNAs were majorly involved in GO terms, such as 'reproduction', 'reproductive process' and the pathways of 'focal adhesion' and 'oocyte meiosis'. In addition, a co-expression network showed that the expression of gametogenesis and sex differentiation related genes, including dmrt3a, tdrd7, sox14, etc were closely associated with the levels of their corresponding ncRNAs. Intriguingly, the dmrt1 circRNA and its target mRNA were detected upregulated both in adult testis and male producing temperature (MPT) embryos. Our findings demonstrated the sexually dimorphic expression profiles of mRNAs and ncRNAs in turtle gonads, which will provide the index to find out the molecular mechanisms behind the sex differentiation in turtles, even in other environmental sex determination (ESD) species.