Toxicological And Mechanistic Studies Of Typical Emerging Pollutants On Tilapia/Zebrafish

Emerging pollutants are a group of newly discovered or recently highlighted toxic and harmful chemicals found in the environment.These pollutants are known for their biotoxicity,environmental persistence,and bioaccumulation characteristics.The consumption of contaminated food and drinking water are the main pathways through which humans are exposed to these pollutants.Over the years,some typical emerging pollutants such as microplastics(MPs)and disinfection by-products(DBPs)have been frequently detected in food and drinking water,presenting significant health risks.To ensure the safety of our diet and drinking water,it is essential to systematically assess the environmental health risks of these pollutants and reveal their key toxigenic mechanisms.In this study,tilapia and zebrafish were used as toxicity evaluation models to explore the toxic effects and mechanisms of typical emerging pollutants,including microplastics and disinfection by-products.The non-targeted screening of suspected key toxic substances based on the endocrine disrupting toxic effects of DBPs provided a scientific basis for the establishment of a safety evaluation system for fish and drinking water.The research findings are summarized as follows:1.The accumulation of microplastics(MPs)in Tilapia’s organs serves as the foundation for studying their toxic effects.To achieve this,we utilized the Py-GC/MS method to detect the accumulation of MPs in the major organs of Tilapia after short-term exposure to environmental doses of MPs.The experimental findings revealed that smaller-sized MPs particles tend to accumulate more in the liver and muscle tissues of Tilapia,while larger-sized MPs particles tend to accumulate more in the intestine.Since the liver is the primary site where the body metabolizes exogenous pollutants,further exploration of the effects of MPs on the liver was necessary.In this regard,we employed various methods such as H&E staining,q RT-PCR,ELISA,RNA sequencing,and other techniques to detect liver metabolism-related enzymes,inflammation,oxidative stress,and pathological damage in Tilapia,as well as screen the key signaling pathways of MPs’ action.Our research uncovered the interference effect of MPs exposure on the liver function of Tilapia and its key molecular mechanism from the molecular level.Specifically,exposure to 0.1 μm MPs at concentrations of 10 and 100 μg/L led to hepatic steatosis in Tilapia.Moreover,short-term exposure to 0.1 μm MPs at an environmentally relevant concentration(100 μg/L)caused the disturbance of endoplasmic reticulum protein homeostasis,activated the unfolded protein response(UPR),specifically activated the PERKe IF2α pathway,induced oxidative stress in the liver,and eventually resulted in hepatic steatosis.2.Zebrafish served as our toxicity evaluation model for studying the effects of disinfection by-products(DBPs)exposure under different drinking water treatment processes.We utilized the behavioral trajectory tracking system of zebrafish to assess the impact of DBPs exposure on zebrafish behavior.We also employed q RT-PCR,ELISA,and other methods to evaluate the effect of DBPs exposure to different drinking water treatments on the endocrine system of zebrafish at the gene and protein levels.Our findings showed that short-term exposure to DBPs inhibited the early embryonic development and swimming behavior of zebrafish.Furthermore,short-term exposure of DBPs under various treatments differentially interfered with the hypothalamic-pituitary axis hormone secretion system of zebrafish.Finally,we analyzed and identified the suspected key toxic DBPs in each treatment process of waterworks based on the differential toxicity of DBPs combined with non-target screening of DBP components.The nontargeted screening results indicated that bis(2-ethylhexyl)phthalate(DEHP)and palmitic acid were the suspected key toxic DBPs inducing endocrine disrupting effects in zebrafish.In summary,our study provides a comprehensive understanding of the environmental health risks and toxicity mechanisms of typical emerging pollutants such as MPs and DBPs.It also serves as a warning for us to exercise greater caution with regard to the global pollution of emerging pollutants.