title: A luciferase reporter gene assay and aryl hydrocarbon receptor 1 genotype predict the LD50 of polychlorinated biphenyls in avian species.
abstract: Birds differ in sensitivity to the embryotoxic effects of polychlorinated biphenyls (PCBs), which complicates environmental risk assessments for these chemicals. Recent research has shown that the identities of amino acid residues 324 and 380 in the avian aryl hydrocarbon receptor 1 (AHR1) ligand binding domain (LBD) are primarily responsible for differences in avian species sensitivity to selected dibenzo-p-dioxins and furans. A luciferase reporter gene (LRG) assay was developed in our laboratory to measure AHR1-mediated induction of a cytochrome P450 1A5 reporter gene in COS-7 cells transfected with different avian AHR1 constructs. In the present study, the LRG assay was used to measure the concentration-dependent effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), and PCBs 126, 77, 105 and 118 on luciferase activity in COS-7 cells transfected with AHR1 constructs representative of 86 avian species in order to predict their sensitivity to PCB-induced embryolethality and the relative potency of PCBs in these species. The results of the LRG assay indicate that the identity of amino acid residues 324 and 380 in the AHR1 LBD are the major determinants of avian species sensitivity to PCBs. The relative potency of PCBs did not differ greatly among AHR1 constructs. Luciferase activity was significantly correlated with embryolethality data obtained from the literature (R(2)≥0.87, p<0.0001). Thus, the LRG assay in combination with the knowledge of a species' AHR1 LBD sequence can be used to predict PCB-induced embryolethality in potentially any avian species of interest without the use of lethal methods on a large number of individuals.
authors: Centre for Advanced Research in Environmental Genomics, Department of Biology, University of Ottawa, Ottawa, ON, Canada K1N 6N5. gmann017@uottawa.ca
authors: Gillian E
authors: GE
authors: Manning
authors: Reza
authors: R
authors: Farmahin
authors: Doug
authors: D
authors: Crump
authors: Stephanie P
authors: SP
authors: Jones
authors: Jeff
authors: J
authors: Klein
authors: Alex
authors: A
authors: Konstantinov
authors: Dave
authors: D
authors: Potter
authors: Sean W
authors: SW
authors: Kennedy
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases / Q000235:genetics; D001717:Birds; D019556:COS Cells; D002522:Chlorocebus aethiops; D004785:Environmental Pollutants / Q000008:administration & dosage / Q000633:toxicity*; D017930:Genes, Reporter / Q000235:genetics; D005838:Genotype; D007928:Lethal Dose 50; D008156:Luciferases / Q000378:metabolism*; D011078:Polychlorinated Biphenyls / Q000008:administration & dosage / Q000633:toxicity*; D000072317:Polychlorinated Dibenzodioxins / Q000008:administration & dosage / Q000633:toxicity*; D018336:Receptors, Aryl Hydrocarbon / Q000235:genetics*; D018570:Risk Assessment; D013045:Species Specificity; D014162:Transfection
chemical_list: D004785:Environmental Pollutants; D000072317:Polychlorinated Dibenzodioxins; D018336:Receptors, Aryl Hydrocarbon; D011078:Polychlorinated Biphenyls; D008156:Luciferases; D001189:Aryl Hydrocarbon Hydroxylases; C108015:cytochrome P-450 CYP1A5