Abstract:Under indoor simulation conditions, the effects of various concentrations and exposure time of Shengli crude oil on the activities of superoxide dismutase (SOD) and catalase (CAT) in the liver of juvenile Cynoglossus semilaevis were studied. The change of SOD and CAT activities versus time showed an increase-decrease-increase trend, and the time for SOD activities to reach the peak value was shorter when exposed to the higher concentrations. In terms of the dose-effect relationship, the activities of SOD and CAT were induced by oil treatment at the lower concentrations and were suppressed at the higher concentrations. A threshold of toxic effects of the oil on the organism was observed, below which there was no toxicity, and the activities of SOD and CAT recovered to the normal level quickly after being released from the pollution stress. In this study, the threshold for CAT was in the range of 0.2~0.4 mg/L, and 1.6~3.2 mg/L for SOD. Beyond the threshold value, the rate of active oxygen production induced by the petroleum pollutant overtook the anti-oxidation eliminating activity of the defense system of the organism, incurring damage to the poisoned organism. The response of CAT activity to the petroleum pollutant was more sensitive than SOD, indicating that CAT can better reflect pollution stress and can be a bio-indicator candidate for petroleum pollution.
