Identification of potential sex-related genes in Siniperca chuatsi

Mandarin fish (Siniperca chuatsi) is an economically important freshwater fish cultured in China. In this species, females grow faster than males. However, due to the lack of available genomic and transcriptome information, the mechanisms of sex differentiation remain poorly understood. In this study, Illumina high-throughput sequencing technology was used to sequence four cDNA libraries; the tissues examined included hypothalamus, pituitary gland, ovary, and testis. A total of 134 124 high-quality unigenes were obtained on average length of 1 361 bp and N50 of 3 312 bp. A search of all-unigene sequences against NR, NT, SwissProt, KOG, KEGG, GO, and InterPro databases resulted in 59 688 (44.50%), 76 329 (56.91%), 50 432 (37.60%), 45 741 (34.10%), 48 760 (36.35%), 5 241 (3.91%), and 46 099 (34.37%) annotations, respectively. In a comparison of ovarian and testicular libraries, 15 289 ovary-biased genes and 10 035 testis-biased genes were identified, including a series of genes related to sex determination and differentiation, such as cyp19a1a, foxl2, sox9, dmrtl, amh, and others. In addition, 49 495 SSRs and 85 899 SNPs were detected in transcriptome data. Quantitative real-time PCR results of 15 sex-related functional genes indicated that RNA-seq data was reliable. This study will contribute to a better understanding of the molecular mechanisms of sex differentiation and development in Mandarin fish.