Towards molecular understanding of species differences in dioxin sensitivity: initial characterization of Ah receptor cDNAs in birds and an amphibian

• Published in: Marine environmental research Vol. 50; no. 1; pp. 51 - 56
• Main Authors: Karchner, S.I., Kennedy, S.W., Trudeau, S., Hahn, M.E.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Oxford Elsevier Ltd 01.07.2000; Elsevier
• Subjects: Amino Acid Sequence; Anas platyrhynchos; Animal, plant and microbial ecology; Animals; Applied ecology; Aryl hydrocarbon receptor; Biological and medical sciences; Biological evolution; Birds; Birds - genetics; Birds - metabolism; Chicken; Chickens; Common tern; Cytochrome P-450 CYP1A1 - biosynthesis; Differential sensitivity; Dioxins; Dioxins - toxicity; DNA, Complementary - chemistry; Ducks; Ecotoxicology, biological effects of pollution; Enzyme Induction - drug effects; Fundamental and applied biological sciences. Psychology; Gallus gallus; General aspects; Genetics of eukaryotes. Biological and molecular evolution; Helix-Loop-Helix Motifs; Humans; Marine; Mice; Mudpuppy; Necturus - genetics; Necturus - metabolism; Necturus maculosus; Phylogeny; Rats; Receptors, Aryl Hydrocarbon - drug effects; Receptors, Aryl Hydrocarbon - genetics; Receptors, Aryl Hydrocarbon - metabolism; Species Specificity; Sterna hirundo; Aryl hydrocarbon receptor; Mudpuppy; Dioxins; Birds; Differential sensitivity; Common tern; Chicken; Chemical pollution; Molecular evolution; Ah receptor; Vertebrata; Sensitivity resistance; Toxicity; Phylogenetic tree; Interspecific comparison; Amphibia; Aves
• ISSN: 0141-1136; 1879-0291
• DOI: 10.1016/S0141-1136(00)00045-3

2,3,7,8-Tetrachlorodibenzo- p-dioxin (TCDD) and related planar halogenated aromatic hydrocarbons (PHAHs) are highly toxic to most vertebrate animals, but there are dramatic species differences in sensitivity, both within and among vertebrate classes. For example, studies in cultured avian hepatocytes have revealed differential sensitivity of birds to PHAHs [ Kennedy et al. (1996). Toxicol. Appl. Pharmacol., 141, 214–230]. Differences in the characteristics or expression of the aryl hydrocarbon receptor (AHR) could contribute to these species differences in PHAH responsiveness. To investigate the molecular mechanism of differential PHAH sensitivity, we have begun to characterize the AHR in white leghorn chicken ( Gallus gallus), Pekin duck ( Anas platyrhynchos), and common tern ( Sterna hirundo), as well as an amphibian, mudpuppy ( Necturus maculosus). Partial AHR cDNAs encompassing the helix-loop-helix and PAS domains were cloned and sequenced. Comparison of amino acid sequences in this region indicated a high degree of sequence conservation among the bird species (97% amino acid identity). The percent identity between bird sequences and either mouse or mudpuppy was lower (79%); the mudpuppy AHR was 74% identical to the mouse AHR. Phylogenetic analysis of these and other AHR amino acid sequences showed that the bird and mudpuppy AHRs were more closely related to mammalian and fish AHR1 forms than to fish AHR2. Future studies include the in vitro expression and functional characterization of AHRs from these and other non-mammalian vertebrates.