PARENT SESSION
PS1 - Wildlife Toxicology
Sunday, 17 November 2002
8:00 AM to 6:30 PM
Exhibit Hall
(P035) Characterization of an aryl hydrocarbon receptor in Baikal seals.
Kim, Eun-Young*,1,2, Hahn, Mark3, Iwata, Hisato2, Tanabe, Shinsuke2, Miyazaki, Nobuyuki4, 1 Ehime Prefecture Institute of Public Health and Environmental Science, Japan2 Center for Marine Environmental Studies, Ehime University, Japan3 Biology Department, Woods Hole Oceanographic Institution, USA4 Marine Research Center, Ocean Research Institute, The University of Tokyo, Japan
ABSTRACT- The aryl hydrocarbon receptor (AHR) is a ligand activated intracellular protein that is responsible for toxic effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and related planar halogenated aromatic hydrocarbons (PHAHs). The structural and functional characteristics of AHRs in aquatic mammals are poorly understood. Baikal seals (Phoca sibirica) inhabiting freshwater environments exhibit high levels of PHAHs in their tissues, and are thought to be highly sensitive to the toxic effects of these compounds, as suggested by recent mass mortality. We cloned and expressed the cDNA of Baikal seal AHR to investigate the potential PHAH sensitivity in aquatic mammals. The Baikal seal AHR cDNA has an open reading frame of 843 amino acid residues with a predicted molecular mass of 94.6 kDa. In alignment of the amino acid sequence, the Baikal seal AHR is most closely related to the harbor seal AHR (98%) and shares 82% and 79% overall amino acid identity with beluga and human AHRs, respectively. Translation product of the Baikal seal AHR cDNA obtained in a yeast expression system showed a single band of approximately 95kDa.The high conservation of AHRs between Baikal and harbor seals indicates that these seals express AHR proteins closely related structually. In our previous study (Kim and Hahn, 2002), the dioxin-binding affinity of the harbor seal AHR was at least as high as that of the AHR from a dioxin-sensitive strain of mouse, suggesting that this seal species may be sensitive to PHAH effects. The functional characterization of the Baikal seal AHR protein is now being investigated.
Key words: Ah receptor, Dioxin susceptibility, Marine mammals, Seals