ANTIOXIDANT ENZYME ACTIVITIES IN GILLS OF FRESHWATER FISH, CYPRINUS CARPIO (L.) AS BIOMARKERS OF EXPOSURE TO ORGANOPHOSPHOROUS PESTICIDEA. PADMANABHA, H.R.V. REDDY, MRIDULA RAJESH, AVINASH BHAT AND MUTTAPPA KHAVIAbstract The present investigation was carried out to evaluate antioxidant enzyme activities in gills of freshwater fish, Cyprinus carpio exposed to organo phosphorous pesticide, quinalphos (25% emulsified concentration). Antioxidant enzyme activities and lipid peroxidation levels were measured spectrophotometrically in gills of fish treated with two sub-lethal concentration of quinalphos viz., 0.275 ppm and 0.55 ppm along with control as reference for 4, 8, 16 and 32 days. Fish exhibited significant increase in lipid peroxidation, suggesting quinalphos-mediated free radical production caused oxidative stress. The experimental concentration of quinalphos evoked different degree of activity in gill tissue; the increase in the activity of glutathione-S-transferase with corresponding increase in the activity of glutathione reductase indicates the glutathione conjugation of the pesticide; activity of superoxide dismutase, catalase and glutathione peroxidase decreased drastically after 32nd day exposure to sub-lethal concentration of pesticide. The significant increase in the intensity of damages in experimental tissue accompanying prolonged exposure, points to the risk of these fishes in chronically polluted environment. The present investigation recommends the utility of antioxidant enzyme activities as a biomarker to assess toxic effects.
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