Transcriptome analysis reveals changes of sex differentiation in brown-marbled grouper (Epinephelus fuscoguttatus)

The brown-marbled grouper (Epinephelus fuscoguttatus) is a protogynous hermaphroditic fish, however, the regulatory mechanism of its sex differentiation is still unclear. In present study, transcriptome sequencing of the gonads at 117 dph and 259 dph was performed to explore the molecular mechanism underlying sex differentiation. A total of 37,434,906,973 clean reads were generated from six cDNA libraries. RNA-seq data showed that the genes in RA signal pathway participate in the early stage of sex differentiation. When the oocyte was observed in histology, the germ cell had finished the preparation of first meiosis with high expression of many meiosis-related genes, including sycp1, sycp3, mlh3, crem, spo11, msh5, and rec8. Our study, for the first time, investigated the transcriptome of the male germ cells from brown-marbled grouper, and identified functional genes, GO terms, and KEGG pathways involved in sex differentiation.