engleski

Assessment of pesticide effects on zebrafish embryos

Aquatic ecosystems are impacted by chemical pollution originating from various sources. Pesticides used in agriculture, forestry, households, etc. eventually enter aquatic ecosystems and can have hazardous effects on aquatic organisms. In aquatic ecotoxicological testing the zebrafish (Danio rerio) is commonly used as a model organism. The early life-stage test using the zebrafish embryo is one of the most widely used tools for assessment of toxicity and mechanisms of action of environmental pollutants. In the present study the acute toxicity of the insecticide diazinon and the herbicide diuron was assessed by conducting the Fish Embryo Toxicity (FET) test. From the results obtained in the FET test, sublethal concentrations for exposure experiments were derived. Subsequently, zebrafish embryos were exposed to the pesticides (0.02, 0.1, 0.5, 1, 2 mg L-1) for 48 and 96 h and enzymatic biomarkers (activities of AChE, CES, EROD, GST, CAT and GPx), fluorescent detection of GSH and gene expression (ache, ces2, cyp1a, gstp1, gpx1a, cat and gsr) was assessed. Both pesticides caused morphological aberrations such as pericardial and yolk sac edema, as well as reduction in spontaneous movements. Toxicity of the investigated pesticides was similar, with 96 h LC50 and EC50 values of 6.72±0.16 and 4.16±0.07 mg L-1 for diazinon, and 6.31±0.19 and 4.37±0.21 mg L-1 for diuron. The results from the exposure experiments showed significant changes in the measured biomarkers and indicated occurrence of oxidative stress. The measurement of endpoints at different organizational levels provided some new insights into the toxicity mechanisms of these pesticides to zebrafish.

zebrafish; pesticide; biomarkers; oxidative stress; gene expression

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