Determination and multivariate statistical analysis of biochemical responses to environmental contaminants in feral freshwater fish Leuciscus cephalus L.

Modulations of 11 prospective biochemical markers of impacts of aquatic pol lutants in liver tissue of chub (Leuciscus cephalus), caught at several sam pling sites of a river with various pollution types and rates, were matched against analytical data of concentrations of organochlorine compounds, pol ycyclic aromatic hydrocarbons (PAHs), and heavy metals. Multivariate princi pal component analysis (PCA) of the field data showed general patterns of b iochemical responses to different types of pollutants and relationships amo ng the biomarkers. Cytochrome P4501A-dependent 7-ethoxyresorufin O-deethyla se (EROD) activity, inducible by 2,3,7,8-tetrachlorodibenzo-p-dioxin and st ructurally related planar compounds, was strongly enhanced in the more cont aminated areas. Compared with polychlorinated aromatic hydrocarbons, PAHs d id not contribute so significantly to EROD induction. Testosterone 6 beta- and 16 alpha -hydroxylase activities, as an expression of the cytochrome. P 4503A27, were slightly increased at several sites but were significantly de creased in samples from some heavily polluted areas. Recently, these activi ties have been suggested as potential biomarkers of exposure to contaminant s that do not induce cytochrome P4501A. In this study, their inhibition or induction was not associated with a specific class of monitored contaminant s, and selectivities of these modulations are still to be investigated. Sim ilar modulations of the prospective biochemical indicators of oxidative str ess, including microsomal glutathione S-transferase activity, cytosolic glu tathione S-transferase with ethacrynic acid, and glutathione reductase, wer e demonstrated by PCA. The pattern of the modulations of the microsomal nic otinamide adenine dinucleotide phosphate (NADPH) -dependent lipid peroxidat ion in vitro differed from the responses of the rest of oxidative stress pa rameters at some sampling sites. Further biochemical markers of oxidative s tress under study, including in vivo lipid peroxidation, in vitro productio n of,reactive oxygen species, and the concentration of metallothioneins did not correlate well with the concentrations of the. contaminants. Principal component analysis demonstrated that the EROD activity, glutathione-depend ent enzymes, and Fe(II)-enhanced lipid peroxidation formed a suitable batte ry of biomarkers of exposure.