Objective To study the effect of paraquat(PQ)on zebrafish(Danio rerio)physiological indicators and its embryonic development with its no-observed-adverse-effect-concentration(NOAEC)were determined.
Methods According to the method recommended by Organization for Economic Co-operation and Development(OECD), the impact of PQ in zebrafish was evaluated with acute exposure test, subacute exposure test and zebrafish embryos developmental toxicity test.
Results Based on the results of probability unit-graphic calculation, 50% lethal concentration(LC50)(96 h)in zebrafish of PQ was 35.71 mg/L(95% confidence interval:26.41-51.30 mg/L). It was suggested that the test substance was a moderately toxic phytocide after an acute exposure. After being exposed to sub-lethal concentrations of PQ for 96 h, significant effects of PQ on SOD, AChE and ATPase activity of zebrafish were detected, the pathologic damage of PQ on liver, kidney were observed. Comparing with the control group, the activity of SOD in livers for experimental groups was significantly induced and enhanced in concentration of 0.9 mg/L; the activity of SOD, ATPase and AChE in livers was decreased in concentration of 3.6-7.2 mg/L. The impact of PQ to zebrafish embryos development was also observed. The 120 hpf hatching ratios of control groups and various concentration groups were 96%, 90%, 78%, and 44% respectively. The 120 hpf death rates were 2%, 4%, 12%, and 28%; and the 120 hpf teratogenicity rates were 2%, 2%, 6%, and 18% respectively. Compared with the control group, retardation of embryo development in 0.10 mg/L and 0.50 mg/L PQ-treated groups were observed obviously. Although no significant differences were detected on body weight, the body length and body width were significantly shrinked in 0.1 mg/L and 0.5 mg/L PQ-treated groups, while comparing with control group. No obvious embryos development abnormalities were observed in 0.02 mg/L PQ-treated groups.
Conclusion PQ exposure caused physiological and pathological changes in zebrafish. PQ delayed embryonic development and even resulted in embryonic lethality and induced the malformation in zebrafish. Under the experimental conditions, the NOAEC of PQ to zebrafish was 0.02 mg/L.
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