Zp. Yuan et al., Is hepatic cytochrome P4501A1 expression predictive of hepatic burdens of dioxins, furans, and PCBs in Atlantic tomcod from the Hudson River estuary?, AQUAT TOX, 54(3-4), 2001, pp. 217-230
Hepatic cytochrome P4501A1 (CYP1A1) expression in fishes is frequently used
to evaluate bioavailable aromatic hydrocarbon contamination of aquatic eco
systems. In controlled laboratory experiments, CYP1A1 expression in naive f
ishes is usually dose-responsive to aromatic hydrocarbons and in field stud
ies levels of gene expression in natural populations often correspond with
known levels of sediment-borne contaminants. We quantified CYP1A1 mRNA leve
ls in juvenile Atlantic tomcod Microgadus tomcod from 42 sites in the Hudso
n River estuary to evaluate the correspondence between hepatic CYP1A1 expre
ssion and hepatic concentrations of persistent halogenated aromatic hydroca
rbons and to determine the utility of CYP1A1 expression as a biomarker in e
valuating the microgeographic distribution of bioavailable contaminants wit
hin a large aquatic ecosystem. We found significant spatial heterogeneity i
n CYP1A1 mRNA levels among collection sites with levels of gene expression
differing in some cases by 23-34 folds. CYP1A1 mRNA expression was highest
in tomcod from the Newark Bay complex and lowest in tomcod from the most up
river collection sites in the main stem of the Hudson River. Although level
s of PCDDs, PCDFs, and PCBs expressed as TCDD TEQs and CYP1A1 mRNA were hig
hest in tomcod from the Newark Bay complex, there was no relationship betwe
en hepatic halogenated aromatic hydrocarbon levels and hepatic CYP1A1 mRNA
in tomcod from sites in the main stem of the Hudson River. These results su
ggest that levels of CYP1A1 expression in fish from sites highly polluted w
ith mixtures of halogenated aromatic hydrocarbons and other xenobiotics may
not always be reflective of levels of bioavailable aromatic hydrocarbon co
ntaminants. Based on these results and earlier controlled laboratory experi
ments, we hypothesize that elevated levels of CYP1A1 expression in tomcod f
rom the Hudson River may be due primarily to PAHs or other contaminants not
measured in this study. (C) 2001 Elsevier Science B.V. All rights reserved
.