Analysis Of Phospholipid Metabolism In Zebrafish Exposed To Fipronil By Mass Spectrometry Imaging

With the wide application of pesticides,their environmental hazards has drawn more and more attention.As a new generation of phenylpyrazole insecticides,fipronil is mainly used for sanitation and pest control of crop lepidoptera and orthoptera.In recent years,the study on the toxicity of fipronil to aquatic organisms mainly focused on the acute toxicity of lower hydrobiont,while the study on fish is lacking.Fish,as the major food of human beings,is at the bottom of the food chain and an important organism in the ecosystem.Therefore,it’s of great importance to study and evaluate of the toxicity of pesticides in fish.Combining with the characteristics of mass spectrometry imaging(in situ\label-free,simultaneously analyzing the spatial distribution of various compounds of the tissue surface,and simple sample preparation process).It has been widely used in many fields such as environmental analysis,chemical analysis,biological analysis,clinical medicine.Matrix assited laser disorption ionization time-of-flight mass spectrometry imaging(AP-MALDI-TOF-MSI)technique was established to scan the biological tissue slices directly and obtain the distribution of substances in the slices.The changes of phospholipid metabolism in zebrafish exposed to nitrile were studied.The choice of matrix and the best parameters of the instrument were optimized.zebrafish slices(10 μm)were covered with 1,5-diaminonapthalene(DAN)matrix,with 100 μm laser lateral size,laser energy of 10-60%(SHIMADZU’s notation),laser spot of 3(40 μm),sum up of 200 laser shots,and detection voltage of 1.75 kV.Under the above conditions,the chemical fingerprint spectra and m/z imaging of zebrafish exposed to fipronil were obtained directly from the whole slices of zebrafish exposed to fipronil in the range of m/z 600-950.ROI(Region of Interest Analysis)method was used to process the MSI data statistics.The results showed that there were significant differences in the mass spectra imaging of phospholipids between the exposed and untreated zebrafish groups.The main differences were phosphatidylcholine(PC),phosphatidyl ethanolamine(PE),phosphatidylserine(PS)and phosphatidylinositol(PI),including PC(34:2),PE(18:0/22:6),PS(18:0/22:6),PI(18:1/20:4)etc.The experimental results show that mass spectrometry imaging technology can observe the changes of metabolites distribution in situ induced by fipronil exposure at the whole animal level,which provides a new method for toxicological study and related metabolic analysis of pesticides in animals.