Sex-related gene expression profiles in various tissues of juvenile Russian sturgeon (Acipenser gueldenstaedtii)

The expression profiles of key genes associated with sex differentiation in vertebrates, namely, amh, ar, cyp19, dmrt1, erα, erβ, foxl2, sox9, star, and vtg, were analyzed in the gonads, liver, muscle, and brain of Russian sturgeon (Acipenser gueldenstaedtii). The aims of this study were to determine in which tissue the signal for sex differentiation primarily occurs, and which factors are most important for gonadal differentiation. The sturgeons included in the study (180 days post-hatching; n = 20) were at the beginning of gonadal differentiation; five females, seven males, and eight individuals with disturbed germinal tissue development were identified. All of the examined genes except for star had diverse sex-related expression profiles in the brain. By contrast, in the gonads, only foxl2 expression was sex-dependent. With the exception of star and cyp19, all of the other genes were expressed in the muscle and liver, but there were no significant differences between sexes. The expression profiles of the analyzed genes in the brain were atypical, indicating feminization. This finding was in agreement with the high occurrence of individuals sharing female and male germinal tissue characteristics. The data presented here suggest that the sturgeon brain is the primary organ that stimulates other organs and tissues to differentiate into male or female, and that dmrt1 and foxl2 play major roles in sex differentiation in this species.