Panel (A) shows nicotine consumption by nicotine concentration. No significant main effect of genotype was observed (F1, 100 = 0.19, p = 0.67), but there was a main effect of nicotine concentration (F4, 100 = 22.55, p < 0.0001). Panel (B) shows total nicotine consumption across the entire study, where no significant effect of genotype was observed (t = 0.44, df = 25, p = 0.67). As seen in panel (C) there were no significant main effects of nicotine concentration (F4, 100 = 2.36, p = 0.06) or genotype (F1, 100 = 0.82, p = 0.37) on total fluid consumption. Finally, in panel (D) there was no main effect of genotype (F1, 100 = 0.0003, p = 1.0) on preference for the nicotine bottle, however there was a significant main effect of nicotine concentration (F4, 100 = 230.7, p < 0.0001). Values are presented as mean (SEM) and n = 14 control and 13 MT1 null mutant.