Fig. 7. Relative mRNA expression levels of RhBG to EF1a in internal organs of K. marmaratus exposed to 0 mmol l^–1 (control) or 1 and 2 mmol l^–1 NH₄HCO₃. In brain, no significant difference was observed between control and ammonia-exposed fish. In liver, RhBG was significantly higher in liver of fish exposed to 2 mmol l^–1 (b) compared to 0 mmol l^–1 (a), but there was no significant difference between 0 (a) and 1 mmol l^–1 ammonia (a,b), as well as between 1 and 2 mmol l^–1 ammonia-exposed fish. In muscle, RhBG in muscle was significantly higher in fish exposed to 2 mmol l^–1 (asterisk) than 0 and 1 mmol l^–1 ammonia. Values are means ± s.e.m.; N=6 (one-way ANOVA, P<0.05).