Estrogen receptor and aromatase mRNA expression in the saccule of male and female Astatotilapia burtoni. (A) ERα mRNA levels differed among all three reproductive phases in females, and subordinate males had higher ERα levels compared to dominant males. Inset: Gravid females had greater ERα mRNA levels in the brain compared to brooding and recovering animals. (B) ERβa mRNA levels were lower in gravid females compared to both brooding and recovering animals, and subordinate males had higher levels than dominant males. (C) There was no difference in saccular ERβb mRNA expression in females or males. (D) Aromatase (CYP19a) mRNA levels differed among female reproductive phases, but there was no difference between male phenotypes. Inset: There was no difference in brain aromatase mRNA levels among different female groups. Data are plotted as relative mRNA levels (mean ± SE) referenced to the geometric mean of two housekeeping genes (18s and G3PDH). Bars with different letters represent significant differences (p < 0.05) and sample sizes are indicated within each bar on the bottom graphs.