Molecular cloning, characterization, and sexually dimorphic expression of five major sex differentiation-related genes in a Scorpaeniform fish, sablefish (Anoplopoma fimbria)

Regardless of how sex is determined, the gonadal genes expressed downstream that regulate sex differentiation are relatively conserved among vertebrates. The goal of this study was to clone and characterize five key sex differentiation-related genes in a Scorpaeniform fish, sablefish (Anoplopoma fimbria). Complete mRNA sequences of foxl2, cyp19a1a, dmrt1, sox9a and amh were cloned, sequenced, and phylogenetically analyzed. The sablefish mRNA sequences exhibited the characteristic domains of each gene. The deduced amino sequences were highly conserved in some cases, such as Foxl2, whereas others, such as Amh, exhibited lower homology to corresponding sequences in other vertebrates. Using quantitative PCRs developed for each gene, we found that foxl2 and cyp19a1a mRNA levels were significantly elevated in juvenile sablefish ovaries compared to testes, whereas dmrt1, sox9a and amh mRNA levels were significantly elevated in testes relative to ovaries. These patterns were upheld in our tissue distribution analyses of adult fish, but overall four of the genes, foxl2, cyp19a1a, dmrt1 and amh, were robust markers of sex in sablefish. This study provides important molecular tools for ongoing work related to sex control in sablefish and exploration of the earliest period of molecular sex differentiation and its regulation.