北京大气PM2.5与惰性SiO2的生物毒性比较

以惰性SiO2颗粒作为模式颗粒,与野外采集PM2.5分别作用于模式生物粟酒裂殖酵母菌(Schizosaccharomyces pombe),旨在通过对比实验确定PM2.5致毒的主要因素.采用紫外分光光度法测定细胞增值率,环境扫描电镜观察颗粒物在细胞表面的附着状态,DHE荧光染色剂显色法测定细胞ROS生成情况,单细胞凝胶电泳实验检测细胞DNA损伤.结果表明,SiO2颗粒在超细粒径尺度(60 nm)下能抑制S.pombe细胞增殖,主要是通过附着在细胞表面来改变细胞外壁的通透性,并不能通过诱导细胞生成ROS而造成对细胞的氧化损伤;而平均粒径较大的PM2.5主要是通过诱导细胞生成ROS对细胞造成氧化损伤,同时可损伤DNA.结论认为PM2.5毒性大小与颗粒物粒径等物理性质并无直接关系.

Comparing Cell Toxicity of Schizosaccharomyces pombe Exposure to Airborne PM2.5 from Beijing and Inert Particle SiO2

To figure out the main factor of PM_2.5 toxicity to cell, this study compared the cell toxicity of Schizosaccharomyces pombe(S. pombe), a model organism, exposed to inert ultrafine SiO₂ particles, a model particle, and airborne PM_2.5 collected from campus of Peking University Beijing China. Using ultraviolet spectrophotometry to measure cell proliferation ratio, and environmental scanning microscope to observe the particle adhesion on the cell surface, and detecting cellular ROS generation with DHE fluorescent dye chromogenic method, and using single cell gel electrophoresis to test cell DNA damage, the experiment results indicated that the ultrafine SiO₂ particles(<60 nm) could inhibit the cell proliferation of S. pombe, mainly through adsorbing onto the cell surface to change the permeability of the cell wall; but it could not induce cells to generate ROS to cause the oxidative damage. PM_2.5, the average particle size of which was larger than that of SiO₂ particles, could cause oxidative damages to cells mainly by inducing cells to generate ROS, and damage DNA simultaneously. It might illustrate that there was no direct relationship between the toxicity of PM_2.5 and its physical properties such as the particle size.