Groups of embryos, non-injected or injected with Ctrl-MO or CYP1A-MO, were exposed to vehicle control (DMSO) or 100 nM FICZ. Effects on expression of Ahr2-related genes were determined at 6, 24 and 48 hpt. A) CYP1A, B) CYP1C1 and CYP1C2, and C) Ahrra and Ahrrb. Relative transcription was calculated using l13 as a reference gene and data from non-injected DMSO control groups at each time point as calibrators. Statistically significant differences in levels of transcription between paired groups of embryos injected with Ctrl-MO and CYP1A-MO were determined by student’s t test and are shown by asterisks (*** p<0.001). The results are based on two repeated experiments (n=4) and are shown as mean ± SD. Note the different y-axis scales used for FICZ vs DMSO graphs.