Cytochrome P4501A and associated mixed-function oxidase induction
in fish as a biomarker for toxic carcinogenic pollutants in the aquatic
environment*
Emel Arinç**, Alaattin Sen, and Azra Bozcaarmutlu
Joint Graduate Program in Biochemistry, Department
of Biological Sciences, Middle East Technical University, 06531 Ankara,
Turkey
Abstract: Polycyclic aromatic hydrocarbons (PAHs), dioxins,
dibenzofurans, and polychlorinated biphenyls (PCBs) present in polluted
environment induce cytochrome P4501A (CYP1A) isozyme in fish, which
in turn results in a marked increased production of carcinogenic metabolites
from PAHs. The induction of hepatic CYP1A in fish by certain classes
of chemicals has been suggested as an early warning system, a "most
sensitive biological response" for assessing environmental contamination
conditions. This has implications for human fish consumption, as well
as for the health status of aquatic organisms. Correlation between elevated
CYP1A and altered steroid metabolism and decreased reproductive success
has been pointed out. The induction of CYP1A and associated enzyme activities
has now been confirmed in a number of field studies. Cases where these
biomarkers have been studied in field conditions will be presented.
Special emphasis will be given to field studies in which the induction
of CYP1A activity, 7-ethoxyresorufin O-deethylase (EROD) activities
and immunochemical detection of CYP1A in leaping mullet and common sole
are used as a biomarker for PAH- and/or PCB-type pollutants along the
Izmir Bay on the Aegean Sea.
*Lectures presented
at the 4th Congress of Toxicology in Developing Countries (4th CTOX-DC),
Antalya, Turkey, 6-10 November 1999
**Corresponding author
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