【摘要】 废弃塑料进入自然界后会分解为各种尺寸的塑料颗粒，其中纳米级塑料颗粒有一定的生物毒性.为探讨单细胞动物对纳米级塑料颗粒胁迫的响应，首先基于急性毒理试验和种群增长试验观察聚苯乙烯纳米颗粒（polystyrene nanoparticles,PSNPs，粒径20nm）对绿草履虫（Parameciumbursaria）的毒性效应，结果显示PSNPs对绿草履虫的生存和细胞分裂有明显的影响，并且有显著的致死效应（24 h半致死浓度为15.93 mg/L）.在此基础之上，选择13.5 mg/L的PS NPs处理草履虫后进行转录组分析（对照组PS NPs浓度为0 mg/L）.基于高通量测序的数据，从绿草履虫的PS NPs处理组与对照组间筛选到了371个差异表达基因（differentially expressed genes,DEGs），包括298个表达上调的DEGs和73个表达下调的DEGs.基于DEGs共获得764个GO(gene ontology)显著富集条目（P <0.05），而富集最显著的前20个GO条目全部与细胞周期及细胞分裂直接相关；而基于DEGs还获得了10条显著富集（P <0.05）的KEGG(Kyoto Encyclopedia of Genes and Genomes)通路，其中细胞周期通路、磷脂酶D信号通路、p53信号通路、孕激素介导的卵母细胞成熟通路和卵母细胞减数分裂通路等5条通路是以MAPK信号通路为中心、与细胞分裂调控相关的代谢通路集群.此外，qRT-PCR测定的10个DEGs的相对表达量与来自RNA-Seq的相对表达量之间较高的相关性验证了转录组高通量测序及分析的可靠性.总之，绿草履虫对PS NPs胁迫的分子响应结果暗示PS NPs对绿草履虫细胞分裂活动有一定程度的扰动.（图6表6参53）更多还原

【Abstract】 After entering the natural environment, discarded plastics decompose into particles of various sizes,among which nanoscale particles exhibit biotoxicity. To investigate the responses of unicellular organisms to nanoplastics, in this study, we initially assessed the toxic effects of polystyrene nanoparticles（PS NPs;diameter: 20 nm） on Paramecium bursaria via acute toxicity tests and population growth experiments. The PS NPs markedly impacted the survival and cellular division of P. bursaria, showing notable lethal effects(24 h LC₅₀ = 15.93 mg/L). Subsequently, transcriptomic analysis was performed after treating P. bursaria with 13.5mg/L PS NPs（control group: 0 mg/L）. High-throughput sequencing revealed 371 differentially expressed genes（DEGs） between the treated and control groups, including 298 upregulated and 73 downregulated genes. Gene Ontology（GO） analysis revealed 764 significantly enriched terms（P < 0.05）; the top 20 most significant terms were directly related to cell cycle and cellular division. Kyoto Encyclopedia of Genes and Genomes（KEGG）pathway analysis revealed 10 significantly enriched pathways（P < 0.05）, including five metabolic pathway clusters centered on the MAPK signaling pathway that regulate cellular division: the cell cycle, phospholipase D signaling, p53 signaling, progesterone-mediated oocyte maturation, and oocyte meiosis pathways. Furthermore,the high correlation between the relative expression levels of 10 DEGs identified using qRT-PCR analyses and those identified using the RNA-Seq analysis verified the reliability of the high-throughput sequencing and transcriptomic analyses. Thus, our findings underscore the molecular responses of P. bursaria to PS NPs; these NPs may disturb cell division-related processes in P. bursaria to a certain degree.更多还原