关键词: 泥鳅, 氰氟草酯, 半数致死质量浓度, 抗氧化酶系统, 组织形态学毒性试验

Abstract: In order to estimate the herbicide toxicity of cyhalofop-butyl to aquatic organisms，with Misgur nus anguillicaudatus as the experimental object，toxic effects of cyhalofop-butyl on Misgurnus anguillicau datus including acute toxicity，physicological toxicity and histomorphological toxicity were studied.The re sults of acute toxicity test showed that the half lethal concentration(LC₅₀) of cyhalofop-butyl to Misgurnus anguillicaudatus in different periods( 24 h，48 h，72 h and 96 h) were 7.254 4 mg/L，7.102 3 mg/L and 6.809 3 mg/L and 6.623 7 mg/L，respectively.The safety concentration(SC) was 2.042 3 mg/L.Through physiological toxicity experiments，the activities of SOD and CAT in Misgurnus anguillicaudatus’s liver increased obviously，and the maximum value appeared in the high concentration treatment group (1.324 8 mg/L) on the first day. The maximum activity value of GSH-Px appeared in the high concen tration treatment group(1.324 8 mg/L) on the third day.Meanwhile，the maximum value of the expres sions of SOD and CAT appeared in the low concentration treatment group( 0.662 4 mg/L) on the seventh day.The expression of GSH-Px reached the maximum on the third day.And these had significant differ ences compared with the control(0 mg/L).Overall，with the extension of exposure time and the concen tration increasing，the activities and gene expressions of SOD，CAT and GSH-Px initially increased and then decreased in the liver of Misgurnus anguillicaudatus.In the histomorphological toxicity test，the wid ened interstitial space could be observed in hepatocytes on the fifth day，while hepatocytes were swelling and more vacuolating on the seventh day in the low concentration treatment group(0.662 4 mg/L) .More over，vacuolation was observed on the first day in the high concentration treatment group(1.324 8 mg/L). With the prolongation of exposure time，hepatocytes swelling and vacuolation deepened，and karyopyknosis could be observed.The experiment results showed that the cyhalofop-butyl had certain toxicity and damage effect on antioxidant enzyme system and histocyte of Misgurnus anguillicaudatus’liver，so it should be used reasonably and scientifically．

Key words: Misgurnus anguillicaudatus; Cyhalofop-butyl, LC₅₀ , Antioxidant enzyme system, Histomor phological toxicity test