Screening Of Toxic Target Organ And Effector Molecules Of Trichloroisocyanuric Acid On Zebrafish

Objective: To elucidate the TCCA-induced acute toxicity in zebrafish this study systematically analyzed the epidemiologic feature of TCCA at different aspects(including populations, animals, organs, cells and bio-moleculars). We identified potential target organs and early stage biomarkers in TCCA-indued acute toxicity. The findings provided scientific basis for the risk accessment of TCCA exposure and explored the molecular mechanisms of TCCA-induced acute toxicity.Methods: The study expounded epidemiological survey of TCCA, chlorinated disinfection by-products, and its associated disease. Provided epidemiological evidence for the experiment. Exposured zebrafish with different concentrations of TCCA solution, observed the acute-toxicity effect, confirmed the 96 h median lethal concentration(LC50) of TCCA on zebrafish. Doses to be used were determined according to LC50. 7 days after exposure, several organs were dissected and analyzed by histological assays, including brain, liver, testis and ovary tissues. Pathological changes of organs observed respectively, preliminary screened the acute-toxicity target organs of TCCA on zebrafish. Morphological changes of target organ liver cells were observed by histopathologic slide and transmission electron microscope. Effector molecules were analyzed by two-dimensional fluorescence difference gel electrophoresis(2D-DIGE) coupled with matrix assisted laser desorption ionization time-of-flight mass spectrometry(MALDI-TOF/TOF-MS), and identified by Western blot. In order to analysis the effector molecule of acute-toxicity effect on TCCA to zebrafish in the level of molecular.Results: Our results showed that the acute-toxicity of different concentrations of TCCA was different in zebrafish. The 96 h LC50 of TCCA in zebrafish was 551.056μg/L. The toxic effects of TCCA on brain, testis and ovary in zebrafish was less, they were not the main target organ of toxicity effect on TCCA. It may caused the acute injury of liver in zebrafish, and the injury enlarged with the increase of the concentration of exposure. Preliminary confirmed the liver was one of the main target organs of toxic effect on TCCA. Moreover, TCCA exposure induced pathological changes of liver tissue in zebrafish(such as cell apoptosis, tissue hyperemia, the tissue formed part of holes and etc).It might cause disease and death in zebrafish that the nucleus and mitochondria were the most serious among them, and appeared dose effect relationship, the injury enlarged with the increase of the concentration of exposure. We found four proteins such as BHMT, HPDA, FABP10 A, ALDOB were in different expression by two-dimensional difference gel electrophoresis and mass spectrometry identification. Expression of BHMTwas decreased significantly and the data showed adose-respose relationship.Conclusion: Acute-toxicity of TCCA in zebrafish belonged to high-toxic chemical according to GSH. Brain, testis and ovary of zebrafish were not the target organ of acute toxicity while the liver might be one of the target organs of acute toxicity on TCCA in zebrafish. BHMT protein might be the early effector molecule in acute toxicity of TCCA in zebrafish.