The Effect Of Multi-walled Carbon Nanotubes On The Selective Toxicity Of Two Typical Chiral Pesticides In Zebrafish

The chiral pesticides of constant usage have led to their accumulation in the environment,and the effects of pesticides on the aquatic organisms have been well documented.And the enantioselective toxicological effects of chiral pollutants have achieved considerable attention.Due to the contaminants always existes as mixtures in aquatic environments,some of co-existing chiral pollutants may change the enantioselective toxic effects of the chiral pesticides in aquatic organisms.The mass production and usage of carbon nanotubes(CNTs)have led to the inevitable release into the environment,a few studies have confirmed that the structure of CNTs is chiral and the effects of CNTs on the toxicity of co-existing pollutants have been well documented.However,knowledge of the effects of CNTs on the enantioselective toxicity of chiral compounds is limited.Therefore,the effects of multi-walled carbon nanotubes(MWCNTs)and carboxylated multi-walled carbon nanotubes(MWCNTs-COOH)on the enantioselective toxicity of two typical chiral pesticides on zebrafish were investigated.The main experiments and results obtained in this paper are as follows:1.Zebrafish were exposed to rac/R/S-ID(0.01 mg/L),MWCNTs(0.05,0.5 mg/L)and a binary mixture of rac/R/S-ID(0.01 mg/L)and MWCNTs(0.05,0.5 mg/L)for 28 days.At the end of exposure,using qPCR to detect the expression of CYP3Cs(Cytochrome P450 3C),apoptosis and EAATs(Excitatory amino acid transporters)-related genes in the livers and brains of fenmale and zebrafish.The results indicated that the expression of apoptosis and CYP3C-related genes was 16.55-44.29 times higher in the livers of males treated with R-indoxacarb than in the S-indoxacarb treated groups.EAAT-related genes were expressed at 1.38-2.56 times higher levels in the brain of females treated with R-indoxacarb than in the S-indoxacarb-treated groups.In the presence of MWCNTs,the expression of caspase-3,cyp3c3,cyp3c4,eaat1 a,eaat1b and eaat2 in the livers of males and brains of females treated with S-indoxacarb were 1.65-15.33 times higher than in the fish treated with R-indoxacarb.Based on these results,MWCNTs affected the enantioselective toxicity of indoxacarb toward zebrafish and sex-specific differences were observed in both the liver and brain of zebrafish.2.Zebrafish were exposed to rac/1R/1S-cis-BF(0.1 ?g/L),MWCNTs/ MWCNTs-COOH(0.5 mg/L),and a binary mixture of rac/1R/1S-cis-BF(0.1 ?g/L)and MWCNTs/ MWCNTs-COOH(0.5 mg/L)for 42 days.After exposure period,using qPCR to detect the expression of immune,endocrine and neurotoxicity-related genes in the livers,gonads and brains of female and male zebrafish.In the livers and brains of female zebrafish,the expression of immune and neurotoxicity-related genes in the 1S-cis-BF treated groups was 3.38-20.92 and 1.45 times higher than in the the 1R-cis-BF treated groups.The expression of immune and endocrine-related genes in the 1R-cis-BF treated groups was 2.84 and 1.78 times higher than in the 1S-cis-BF treated groups in the livers and gonads of male fish.When the enantiomers of cis-BF were in combination with MWCNTs/MWCNTs-COOH,the enantioselective toxicity was changed: when co-treated with MWCNTs,the transcription levels of immune and neurotoxicity-related genes in the 1R-cis-BF treated groups was 4.45 and 3.84 times higher than that in the 1S-cis-BF treated groups in the livers and brains of female zebrafish;when co-treated with MWCNTs-COOH,the expression of immune and endocrine-related genes in the 1S-cis-BF treated groups was 5.39-6.93 and 3.19 times higher than that in the 1R-cis-BF treated groups in the livers and gonads of male zebrafish.The effects of MWCNTs and MWCNTs-COOH on the enantioselective toxicity of cis-BF toward zebrafish were different,specifically,MWCNTs altered the enantioselective expression of immune and endocrine-related genes in the livers and brains of female fish when exposed to 1R/1S-cis-BF,while MWCNTs-COOH altered the enantioselective expression of immune and neurotoxicity-related genes in the livers and gonads of male fish when exposed to 1R/1S-cis-BF.In general,the co-existence of nanomaterials in the aquatic environment might change the enantioselective toxicity of chiral pesticides to aquatic organisms,and sex-specific differences were observed.Therefore,it is necessary to take the interference of co-existing pollutants into consideration when evaluating the toxicological effects of chiral pollutants toward aquatic organisms.