Wildlife ecotoxicology of chlorinated dioxins and cytochrome P450 1A - The Lake Biwa cormorant story


Thursday, August 2, 2012
Redfield Auditorium - 12:00 Noon
Dr. Akira Kubota
Visiting Investigator, Biology Department

Chlorinated dioxins and related compounds (DRCs), including polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and dioxin-like polychlorinated biphenyls (DL-PCBs) have been found in a variety of environmental matrices, due mainly to their high persistence and bioaccumulation.  A 1999 report by the United Nations Environment Programme showed that emission of PCDD/DFs to air in 1995 in Japan was the highest among the 15 countries reported, which was about 1.5-fold higher than those in the United States, the second highest ranking country.  The regulation on DRC emission in Japan has been placed under the “Law Concerning Special Measures against Dioxins” implemented in 1999.  The Ministry of the Environment initiated a nationwide project “Survey on the State of Dioxins Accumulation in Wildlife”, together with compiling the DRCs emission inventory.  This study is part of that project.  This presentation will begin with temporal trends of residue levels of DRCs in common cormorants (Phalacrocorax carbo) collected from Lake Biwa, Japan, in comparison to the temporal trends of DRC emissions.  Tissue-, growth stage-, gender-, and species-specific accumulation features will also be addressed.  This will be followed by an assessment of cytochrome P450 1A (CYP1A) as a biomarker for DRC exposure, and an evaluation of metabolism and toxicokinetics of DRCs that occur as a result of CYP1A induction.  Finally, enzymatic properties of the recombinant cormorant CYP1A proteins that were heterologously expressed in yeast cells will be addressed.