Toxicity On Aging And Aging-related Phenotypes By Nanopolystyrene And The Underlying Mechanisms In Caenorhabditis Elegans

Due to the potential toxicity of nanoplastic particles on human health and organisms,it has aroused the great attention.Although some research works have been conducted on the toxicity of nanopolystyrene exposure at various aspects on Caenorhabditis elegans and the underlying mechanisms,the potential long-term adverse effects on organisms are still largely unclear.In this study,model organism of Caenorhabditis elegans was used as animal model.Two different exposure durations(from L1-larvae to adult day-3 and from adult day-1 for 8-day)were performed to investigate the toxicity of long-term nanopolystyrene exposure on lifespan and aging-related phenotypes and the underlying mechanisms in nematodes.1.Toxicity of nanopolystyrene exposure from L1-larvae to adult day-3 on lifespan and aging-related phenotypes and the underlying mechanismsAfter exposure from L1-larvae to adult day-3,the potential toxicity of exposure to nanopolystyrene(100 nm)on lifespan and aging-related phenotypes was examined.Nanopolystyrene at high concentrations(100 and 1000 μg/L)reduced the lifespan.Although nanopolystyrene(1 or 10 μg/L)did not affect the lifespan,nanopolystyrene(1 or 10 μg/L)could induce the more severe intestinal reactive oxygen species(ROS)production and decrease in locomotion behavior during the aging process compared with control.Moreover,nanopolystyrene exposure could cause the severe decrease in expressions of some innate immune response genes,hsp-6 gene,and genes encoding manganese-superoxide dismutases(Mn-SODs)during aging process,suggesting the severe suppression in innate immune response,inhibition in antioxidation defense system,and suppression in mitochondrial unfolded protein response(mt UPR)by nanopolystyrene exposure.Therefore,our results highlight the potential of long-term exposure to low doses of nanopolystyrene in affecting aging-related phenotypes during the aging process in nematodes.2.Toxicity of nanopolystyrene exposure from adult day-1 for 8-day on lifespan and aging-related phenotypes and the underlying mechanismsAfter exposure from adult day-1 for 8-day,the potential toxicity of exposure to nanopolystyrene(30 nm)on lifespan and aging-related phenotypes was examined.After the exposure,only 1000 μg/L nanopolystyrene reduced the lifespan.In contrast,nanopolystyrene ≥ 1 μg/L decreased locomotion behavior and activated oxidative stress.Meanwhile,in 10 μg/L nanopolystyrene exposed nematodes,both expression of SOD-3,a Mn-SOD,and autophagy induction as indicated by LGG-1::GFP expression were significantly increased.RNAi knockdown of daf-2 encoding an insulin receptor enhanced the autophagy induction,and RNAi knockdown of daf-16 encoding a FOXO transcriptional factor in insulin signaling pathway suppressed the autophagy induction in 10 μg/L nanopolystyrene exposed nematodes.Moreover,DAF-16 acted upstream of LGG-1,an ortholog of Atg8/LC3,to regulate the toxicity of nanopolystyrene toxicity in inducing ROS production and in decreasing locomotion behavior at adult day-9.Therefore,our data implied the potential toxicity of exposure to nanopolystyrene at predicted environmental concentrations at multiple aspects during the aging process on environmental organisms.