Fig. 1

Zebrafish AHR genes are differentially expressed during development.

(A) Schematic of genomic arrangement of zebrafish AHR genes. Note linkage of ahr1b and ahr2 (~3 kb intergenic distance). (B) Experimental design. Embryos were exposed to DMSO or 1 uM BNF for 4 hrs starting at 48 hpf, then fixed in 4% PFA for ISH. (C-H) Stereomicroscope images of whole mount ISH in 52 hpf embryos exposed to DMSO or 1 uM BNF showing expression of ahr1a (C, D), ahr1b (E, F) and ahr2 (G, H). Boxes indicate region of high magnification image in inset. Numbers indicate embryos with indicated expression pattern/total embryos analyzed. Scale bar is 500 um. (I-N) High magnification images of trunk in 52 hpf embryos exposed to DMSO or 1 uM BNF showing expression of ahr1a (I, J), ahr1b (K, L) and ahr2 (M, N). No staining evident for ahr1a or ahr1b in either condition. ahr2 expression is detected in DLAV, gut (white arrowhead) and region between DA and PCV (white bracket), and is increased by BNF-treatment. Scale bar is 100 um. Abbreviations—AHR: aryl hydrocarbon receptor, BNF: beta-naphthoflavone, DA: dorsal aorta, DLAV: dorsal longitudinal anastomotic vessel, DMSO: dimethylsulfoxide, hpf: hours post fertilization, ISH: in situ hybridization, kb: kilobase pair PCV: posterior cardinal vein, PFA: paraformaldehyde.