Study On The Effect Of Heavy Metals And Pesticide Stress On Zebrafish Electrocardiogram

As the environment in which people depend,the water environment cannot be ignored,and it has attracted the attention and attention of the world today.In recent years,various pollutants in water have gradually increased,such as herbicides,insecticides and other organic pesticide poisons,as well as some heavy metal compounds such as cadmium,lead,copper,antimony and mercury.These pollutants are transmitted through the water pathway and enriched through the food chain,causing damage to the viscera,intestines,brain,ankles and reproductive system of the organism,interfering with the endocrine system and affecting normal metabolism and physiological functions.Since aquatic organisms have their own perceptual responses to changes in the water environment,the use of biological water quality monitoring methods is increasing at home and abroad.The electrocardiogram?ECG?of fish can reflect the toxic effects of exposure to various chemical contaminants.Zebrafish,a model organism,was used to study the changes of ECG parameters of zebrafish under different pollutant stresses in water environment,and to explore the effects of environmental pollutants on zebrafish ECG.In this study,the zebrafish ECG acquisition method was considered and tested in many aspects,and the deficiencies were repeatedly improved.The ECG acquisition technology with the least damage,the most convenient operation and the most effective zebrafish was studied.The method uses silver needles having diameter of 0.25 mm as acquisition electrodes.The positive and negative electrodes are respectively located on the left and right sides of the zebrafish heart,and both electrodes are buried in the pericentric cavity.The collected ECG signals are subjected to denoising filtering to obtain clearer ECG signals.This study mainly analyzed the changes of zebrafish ECG parameters under the stress of heavy metal pollutant copper sulfate?CuSO₄?and organic pesticides such as deltamethrin?DM?and atrazine?ATZ?.Each study was set up into four groups based on the toxic concentration of the contaminant to the zebrafish:one control experiment group and three contaminant exposure test groups.The three exposure groups were 0.1TU group,0.5TU group and surface water standard concentration group,and the surface water standard concentration group was set according to the national surface water environmental quality standard concentration?GB3838-2002?.Each experimental group was set with seven ECG sampling time points?0h,2h,4h,8h,16h,32h,48h?.The ECG signals of three zebrafish were collected at each time point.Three parallel experiments were set up for each set of experiments.The importance of ECG parameters in zebrafish under contaminant stress was analyzed to illustrate the importance of different ECG parameters in environmental stress assessment.The effects of two types of contaminants on zebrafish ECG parameters?P wave,R wave,T wave and PR interval,QRS complex,QT interval?and heart rate were analyzed by exposure to heavy metal contaminants?CuSO₄?and exposure to pesticide contaminants?DM,ATZ?.The results showed that the pollutants inhibited ECG and heart rate to a certain extent,leading to the decrease of heart rate,the decrease of ECG amplitude,the prolongation of ECG interval,and the dosage effect and time effect of zebrafish.Through different statistical analysis methods,the best and most effective evaluation parameters that can be used to evaluate the pollution of water bodies are screened and extracted.The final QRS complex and QT interval were most similar to CuSO4 stress and DM and ATZ stress on SOM patterns,respectively.And their significant correlation was the best.They are the best ECG parameters for the highest fitted model of linear regression equations.The results show that the zebrafish QRS complex will be an effective indicator for monitoring Cu²⁺pollution in the aquatic environment.The QT interval can be used as an effective ECG parameter for monitoring DM and ATZ pollution in the water environment.