Toxicity And Bioconcentration Of Boscalid On Zebrafish

Boscalid is one of the most commonly used fungicides and mainly affect through the mitochondrial respiratory chain succinic acid Coenzyme Q reductase activity inhibition,so that the body of electron transfer is interfered,thus hindering the energy production and energy supply.It is playing an important role in the effective inhibition of spore germination,disease transmission,and promotion of agricultural production and development.Boscalid is commonly used to control powdery mildew,gray mold,stem rot and other diseases.In this paper,zebrafish was selected as test organism and the effects of boscalid in zebrafish were determined by semi-static test.This paper is studied the acute and sub-acute toxic effects of boscalid on zebrafish embryos and adult fish;the effect of boscalid on antioxidant enzymes of zebrafish liver and gill and the effect of boscalid on mechanism of action in zebrafish;the bioconcentration and elimination of boscalid in zebrafish.This study showed that boscalid was moderately toxic and moderately bioconcentratal to zebrafish,it induced oxidative stress,a significant decrease in the activities of succinate dehydrogenase(SDH)and complex ?.Provide overall and systematic information for the further ecotoxicological evaluation of boscalid on aquatic environment.The results showed that the acute toxicity of boscalid to embryos and adult fish(96 h-LCso):adult fish(1.84 mg/L)>embryos(1.26 mg/L).Boscalid is moderate toxicity to embryos and adult fish,and the inhibitory to the heartbeat was gradually enhanced with the increase of concentration.The study shows that boscalid can increase the content of MDA in organism,thereby inducing oxidative stress.The activity of SOD,CAT,POD and GPx increased first and then decreased with the increase of exposure time and concentration.The highest activities of the four enzymes in the liver were 124.16%(0.32 mg/L),121.71%(0.32 mg/L),127.65%(0.16 mg/L)and 124.13%(0.16 mg/L)to the control,respectively.The highest activities of the four enzymes in the gill were 121.51%(0.32 mg/L),118.85%(0.32 mg/L),129.65%(0.32 mg/L),114.90%(0.08 mg/L),while the lowest in the liver were 67.16%,70.51%,54.49%,60.74%to the control,respectively.In the gill the activity of SOD,CAT,POD and GPx were 80.50%,77.11%,70.51%,and 73.40%,respectively,and both were reached at 0.32 mg/L.Increased enzymes activity may be an adaptive response to toxin exposure,however,antioxidant enzymes could not remove the excess superoxide radicals in a timely manner,resulting activity beyond the body's regulatory function,which ultimately inhibited antioxidant enzyme activity or synthesis,and even induced oxidative damage.The results showed that condition factor(CF),hepatosomatic(HSI)and branchiasomatic(BSI)were increased as the exposure time and concentration increased.After exposed to 21 d at 0.32 mg/L,they showed significant results compared with control(93.04%,175%,122%,respectively).The activity of SDH in the liver and gill was 32.64%and 56.48%compared to control,respectively,and the complex ? was 60.53%and 66.35%to the control,respectively,after exposed to 21 d at 0.32 mg/L.The change of CF,HSI and BSI may indicate that the inhibition of succinate dehydrogenase(SDH)and complex ? induce energy supply was insufficient,causing certain toxicity to the body tissues.The method of bioconcentration and elimination of boscalid in zebrafish was established.Boscalid in zebrafish was extracted with acetonitrile by ultrasonic extraction,and purified by florian silica solid phase extraction cartridge.UV detection wavelength was 210 nm.The retention time of boscalid was approximately 7.60 min.The mobile phase was acetonitrile and water(65:35,V/V).Zebrafish was exposed at 0.08 and 0.32 mg/L,the biological concentration factor(BCF)of boscalid were 35.50(0.08 mg/L)and 36.72(0.32 mg/L),respectively,and the bioconcentration ability of boscalid to zebrafish was moderate.The maximum concentration and balance periods were both found in time of 14?28 days.When the contaminated zebrafish were transferred to the water without boscalid,the boscalid in zebrafish began to decline rapidly on the first day.