Su Guanyong, Zhang Xiaowei, Giesy John P, Musarrat Javed, Saquib Quaiser, Alkhedhairy Abdulaziz A, Yu Hongxia
State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210089, China.
Department of Biomedical Veterinary Sciences and Toxicology Centre, University of Saskatchewan, Saskatoon, SK, S7N 5B3, Canada.
Environ Sci Pollut Res Int. 2015 Nov;22(22):17434-42. doi: 10.1007/s11356-015-4507-6. Epub 2015 May 5.
Increasing production and applications of nano zinc oxide particles (nano-ZnO) enhances the probability of its exposure in occupational and environmental settings, but toxicity studies are still limited. Taking the free Zn ion (Zn(2+)) as a control, cytotoxicity of a commercially available nano-ZnO was assessed with a 6-h exposure in Escherichia coli (E. coli). The fitted dose-cytotoxicity curve for ZnCl2 was significantly sharper than that from nano-ZnO. Then, a genome-wide gene expression profile following exposure to nano-ZnO was conducted by use of a live cell reporter assay system with library of 1820 modified green fluorescent protein (GFP)-expressing promoter reporter vectors constructed from E. coli K12 strains, which resulted in 387 significantly altered genes in bacterial (p < 0.001). These altered genes were enriched into ten biological processing and two cell components (p < 0.05) terms through statistical hypergeometric testing, strongly suggesting that exposure to nano-ZnO would result a great disturbance on the functional gene product synthesis processing, such as translation, gene expression, RNA modification, and structural constituent of ribosome. The pattern of expression of 37 genes altered by nano-ZnO (fold change>2) was different from the profile following exposure to 6 mg/L of free zinc ion. The result indicates that these two Zn forms might cause toxicity to bacterial in different modes of action. Our results underscore the importance of understanding the adverse effects elicited by nano-ZnO after entering aquatic environment.
纳米氧化锌颗粒（nano-ZnO）产量和应用的增加，提高了其在职业和环境中的暴露可能性，但毒性研究仍然有限。以游离锌离子（Zn(2+)）作为对照，在大肠杆菌（E. coli）中进行6小时暴露实验，评估一种市售纳米氧化锌的细胞毒性。ZnCl2的拟合剂量-细胞毒性曲线比纳米氧化锌的曲线明显更陡。然后，利用由大肠杆菌K12菌株构建的1820个修饰绿色荧光蛋白（GFP）表达启动子报告载体文库的活细胞报告分析系统，对暴露于纳米氧化锌后的全基因组基因表达谱进行分析，结果显示细菌中有387个基因发生显著改变（p < 0.001）。通过统计超几何检验，这些改变的基因富集到十个生物学过程和两个细胞成分（p < 0.05）术语中，强烈表明暴露于纳米氧化锌会对功能基因产物合成过程造成极大干扰，如翻译、基因表达、RNA修饰和核糖体的结构组成。纳米氧化锌改变的37个基因（倍数变化>2）的表达模式与暴露于6 mg/L游离锌离子后的情况不同。结果表明这两种锌形态可能以不同作用方式对细菌产生毒性。我们的结果强调了了解纳米氧化锌进入水环境后所引发的不利影响的重要性。
