Fig. 5

Regulation of cyp1b1 by AHR.

(A-E) Overview pictures of cyp1b1 expression at 52 hpf in DMSO or BNF-treated WT (A), ahr1a -/- (B), ahr2 -/- (C), ahr1b,2 -/- (D) and triple AHR mutants (E). No changes in expression pattern were evident in DMSO-treated embryos that lacked any AHR genes. Induction in the skin by BNF was dramatically reduced in ahr2 -/- (compare A to C, lower panels). Scale bar is 500 um. F-T) High magnification images of blood vessels in 3 different planes of the head vasculature: the LDA (F-J), the hindbrain blood vessels (K-O) and the hindbrain capillaries (P-T) in all genetic combinations with DMSO and BNF treatment. Black asterisks denote approximate location of liver. Yellow arrowheads label individual CtAs. Note maintenance of endogenous cyp1b1 expression in the ear (K-O, upper panels) and head (P-T, upper panels) of all mutants. Expression of cyp1b1 was not detected in the liver for either treatment in any genetic combination (F-J). Note lack of BNF-induced staining in LDA of ahr2 mutants, but strong staining in PHBCs (H and M, lower panels). Numbers indicate embryos with indicated expression pattern/total embryos of that genotype analyzed. Scale bar is 100 um. Abbreviations–AHR: aryl hydrocarbon receptor, BNF: beta-naphthoflavone, CtA: central artery, CYP: cytochrome p450, DMSO: dimethylsulfoxide, hpf: hours post fertilization, LDA: lateral dorsal aortae, PHBC: primordial hindbrain channel, WT: wildtype.