Research On Hormesis Effect And Molecular Mechanism Of Nanoparticles On Aquatic Model Organisms

With the rapid development of nanotechnology,the application of nanomaterials also covers all aspects of industrial life.With the wide application of nanomaterials in production and manufacturing,the negative environmental effects brought about by nanomaterials have gradually attracted people’s attention.In the production and application of nano-materials,they are usually discharged into natural water through point sources,thus forming nano-particle contaminants in the water environment.This type of nanoparticle in water has long-term occurrence,is difficult to degrade,and has a low dose.However,in the traditional toxicological evaluation indicators,the ecological risk assessment of pollutants is biased towards its impact on the behavior of model organisms such as birth,death,and growth inhibition.The doses chosen for this type of study are often higher than the actual doses of nanoparticles in actual water bodies.Therefore,such conclusions can only give the toxicity assessment of such pollutants,but they cannot correctly reflect the true impact on the ecological environment.Especially for the low dose positive stimulating effect(hormesis)of nanoparticles on aquatic organisms,no comprehensive and objective evaluation has been made.However,there is no bidirectional dose-response model for hormesis effect in the linear model of contaminant risk assessment.Therefore,we have made some explorations for the early warning of new types of nanoparticle pollutants in our research.The C60 and silver nanoparticles(AgNPs)used in this study are representative of the new nano-particle contaminants in the water body and are model organisms of large-sized Daphnia and Scenedesmus obliquus.Low-dose exposures were performed at real environmental concentrations,and the molecular mechanisms of hormesis effects of nanoparticle contaminants on aquatic organisms were investigated by advanced histological analysis and analysis techniques.The specific content of this study includes:The effect of low concentration of C60 on the oxidative stress of large earthworms was studied in the early stage.Later,the hormesis effect in the oxidative stress response focused on the detection and analysis of the transcriptome.By studying the effects of low concentration of AgNPs on the metabolites of S.obliquus after long-term exposure to Scenedesmus obliquus,there are significant metabolic pathways.Research indicates:By characterizing the activities of CAT and SOD,it was shown that the Hormesis effect of large gills on n C60 gradually shifts to the left as the exposure time passes.This result was not only confirmed by the antioxidant kinases,but we also detected the corresponding changes in concentration when glutathione was present in the cells as a buffer component of the body’s antioxidant activity.The change trend is similar to the change trend of antioxidant kinases.This result is another example of the better proof of the Hormesis effect of n C60 on the antioxidative stress of large ticks and Hormesis with the exposure time.The effect interval is also constantly migrating to low concentrations,eventually reaching full inhibition.We then used transcriptome technology to examine the genotoxic effects of large ticks exposed to n C60 for 48 h.The results showed that the expression levels of the phospholipase PLA2 G and phospholipase D gene genes in the large prince cells of the treatment group were down-regulated,resulting in a decrease in the synthesis of phospholipase,which in turn affected the normal digestive function of large quails and the metabolic process of phospholipid lipids.The differential expression of ND5,SDHD,and COX1 genes in the oxidative phosphorylation metabolic pathway further demonstrated that large tick individuals are very sensitive to the toxicity of n C60.In studies on the effects of AgNPs on Scenedesmus obliquus,algae cells were exposed to AgNPs for 48 hours and passed through metabolomics techniques.Thirty metabolites were identified,of which nine species had significant changes compared to the control group.These include D-galactose,sucrose,and D-fructose.These carbohydrates are involved in the synthesis and repair of cell walls.Glycine is an important amino acid component of glutathione,which increases with increasing exposure concentration of AgNPs and may counteract the increase in intracellular oxidative stress.These results provide new insights into the toxic effects and mechanisms of C60 and AgNPs.The results of these histological tests may be useful biomarkers in future studies for the early detection of environmental risks of C60 and AgNPs.