Transcriptomic analysis provides insights into gonad development and sex reversal of cultured largefin longbarbel catfish (Hemibagrus macropterus).

The largefin longbarbel catfish (Hemibagrus macropterus) is an important commercially cultured fish in southwestern China, whose regulatory mechanism of gonad development remains unknown. In this study, the first gonadal transcriptome sequencing of immature male, female, and intersexual individuals were performed. A total of 28,543 genes was annotated, of which 12,028, 6283 and 8019 differentially expressed genes (DEGs) were detected by pairwise comparisons of ovary versus (vs.) testis, ovary vs. intersex, and testis vs. intersex. Besides, 26 male-biased, 24 female-biased, and 7 intersex-biased DEGs were screened. Representative pathways related to gonadal development and sex reversal were further enriched. Interestingly, apart from the reproduction-related genes and pathways, apoptosis-related DEGs (bcl2, myc, caspase3 and tp53) and pathways such as JAK-STAT signaling pathway and P53 signaling pathway, were suggested to be involved in the sexual reversal process. The intersexual gonad might be developed by the sex change from ovary to testis, with transcriptions of female-biased genes reduced and male-biased genes increased. Relative real time PCR results of 14 DEGs verified the reliability of transcriptome data. These results will benefit our understanding of gonad development regulations, and further be useful for the achievement of improved artificial propagation of largefin longbarbel catfish.