Toxicological Study Of Nanoplastics And Polycyclic Aromatic Hydrocarbons On The Clam(Mactra Veneriformis)

In this study,we measured and analyzed the Phe content in the gills,visceral mass,and coat membrane of the four-horned clam(Mactra veneriformis)under single and combined stress of phenanthrene(Phe)and polystyrene nanoplastics(PS-NPs),as well as the oxidative stress indicators in the clam tissues(malondialdehyde content,total superoxide dismutase and glutathione activity)in the clam tissues.On this basis,the metabolomic analysis of the tissues of four-horned clams under stress with different concentrations of Phe and PS-NPs screened 99 metabolic pathways,105 Differential Expressed Metabolites(DEMs),and resolved four stress-related metabolic pathways.1.Accumulation of Phe and PS-NPs singly and in combination with stress in the four-horned clamTo investigate the accumulation of Phe and PS-NPs in the gill,visceral mass and coat membrane of the four-horned clam,a blank control group(Control),three Phe single treatment groups: Phe 20μg/L,Phe 50μg/L,Phe 100μg/L;three Phe and PS-NPs combined stress treatment groups: Phe 20μg/L +PS 1mg/L,Phe 50μg/L +PS 1mg/L,Phe 100μg/L +PS1mg/L.The experimental results showed that under single Phe stress,the higher the concentration,the higher the accumulation of Phe in tissues and organs,and the accumulation concentration of Phe in organs was: coat membrane < gill < visceral mass.The bioaccumulation level of organic pollutants in clams can also reflect the changing characteristics of organic pollutants in the environment.2.Effects of single and combined stress of Phe and PS-NPs on oxidative stress indicators in the four-horned clamOn this basis,three index changes of malondialdehyde content,total superoxide dismutase and glutathione activity were detected and analyzed in four-horned clams exposed to single and combined stress of Phe and PS-NPs at 2d,4d,6d,8d,and 9d and 11 d,i.e.purification 1d and 3d.The experimental results showed that under the single stress of Phe,the content of malondialdehyde,total superoxide dismutase and glutathione activity showed significant changes(p<0.05)with the increase of Phe concentration compared to the blank group.When Phe was co-stressed with PS-NPs,the content of malondialdehyde,total superoxide dismutase,and glutathione activity showed significant changes(p<0.05)with increasing Phe concentration compared to PS 1 mg/L,and were significantly greater than the changes in content when stressed with single Phe.3,Effect of single and combined stress of Phe and PS-NPs on metabolism of tetrahymena clamsDuring the experimental study of bivalve tissues using non-targeted metabolomics techniques,a technique commonly used in metabolomics was applied: liquid chromatography-mass spectrometry coupling(LC-MS)technique.Metabolomic analysis was applied to construct differential metabolite profiles of tetrahymena clam tissues under single combined stress of Phe and PS-NPs,to visualize the biological interpretation of the screened differential metabolites by KEGG pathway enrichment,and to verify the expression of differential metabolites in blank and experimental groups,control and experimental groups,clam tissues using Met PA(Metaboanalyst)assay.levels.In this project,99 metabolic pathways and 105 DEMs were screened and found to be mainly related to ABC transporter protein metabolism,protein absorption and digestion,amino acid anabolism and intestinal immune system pathways.Understanding the metabolic changes in clam tissues under stress can help to understand the regulatory mechanisms and metabolic mechanisms of metabolites at the cellular level in target organs.