Study On The Effects Of Typical Environmental Pollutants On Swimming Behavior Of Zebrafish Larvae

Various anthropogenic chemicals,such pesticides and pharmaceuticals,have been detected in the aquatic environment and reported to cause severe ecological risks.Zebrafish behavioral model is prevalent and potential in chemical screening and toxicity evaluation.However,the applications of zebrafish behavioral assays remain limited because of incompetent monitoring procedure design and inconsistent test methodology.Here,in order to establish a comprehensive method based on zebrafish larvae for rapid toxicity evaluation of chemical contaminants,the test conditions were optimized and multiple behavioral parameters were developed.Furthermore,to validate the reliability and investigate specificity of the method we developed,the behavioral effects of a set of 28 typical chemicals with various mode of actions(MOAs)were evaluated.The main conclusions of this study are described as follow.1.To screen the best behavioral test conditions for zebrafish larvae,the behaviors of zebrafish larvae at same developmental period in different well plates and zebrafish larvae at different developmental periods in the same of well plate were compared.The results showed that among 6,12,24,48 and 96-well plates,the swimming ability of zebrafish was limited in 48-and 96-well plate,and thus,the most suitable plate for behavior testing was the 24-well plate.The swimming ability of zebrafish larvae was enhanced at the 5 day-post fertilization(5 dpf),and there was no difference between accumulated distance of 5,6 and7 dpf,so the most suitable period for behavior testing was the 5 dpf.2.To construct evaluation system with multiple behavior parameters of zebrafish larvae behavior tests,this study selected different parameters,such as the accumulated distance(AD),mobility state frequency(MSF),mobility after light-dark transition and acceleration tapping stimulus.And their baselines(means±SD)are 181.86±91.00 cm(30minutes AD),961.29±570.88(30 minutes MSF),-0.54±0.38 cm/s~2(1-s acceleration after tapping in the dark),-0.38±0.39 cm/s~2(1-s acceleration after tapping in light),13.95±6.68(1s activity after light turning off)and 12.667±7.17(1s activity after light turning on).The results indicated inevitable individual differences of zebrafish larvae in the behavior test.3.This study monitored the behavior of zebrafish larvae after exposure to chemicals,and evaluated the effects of chemicals on the behavior parameters of zebrafish larvae.The effects of chemicals in different parameters indicated the necessity of adopting multi-parameter evaluation system,for example,exposure to Cd CL2 significantly reduced the AD of zebrafish larvae,but significantly increased MSF.Furthermore,this study found that estrogenic effect chemicals caused hyperactivity and neurotoxins led to hypoactivity.In conclusion,the behavioral test method developed in this experiment could be used for toxicity assessment and is potential for pollutants screening.