Figure 2.

Expression of the candidate 'housekeeping' genes in fathead minnow gonad following exposure to 10 ng EE₂/L. (A) 18S rRNA, (B) rpl8, (C) ef1a, (D) g6pd, (E) bactin, (F) gapdh, (G) hprt1, and (H) tbp. The results are represented as means ± S.E.M. and expressed as fold-increase in expression from the control which was arbitrarily set as the 1× expression of the gene. Each treatment group consisted of eight male and eight female fish and each fish was analysed in triplicate. Statistically significant differences in gene expression between control and EE₂-treated fish for each sex are denoted as follows: * P < 0.05, ** P < 0.01, *** P < 0.001 (Student's t-test).