重金属诱导拟南芥原生质体DNA 损伤的单细胞凝胶电泳检测

以拟南芥原生质体为实验体系, 研究不同浓度的3种重金属离子对拟南芥原生质体的毒性和DNA损伤的差异。结果表明, 用1-5 mmol.L-1的Zn2+、Cd2+ 和Cu2+分别处理的拟南芥原生质体, 2 小时内活力逐渐下降, 并表现出明显的浓度依赖性;与相同浓度的Cd2+ 和Cu2+ 相比, Zn2+对拟南芥原生质体活力的影响程度较小, 表现出较低的毒性。单细胞凝胶电泳检测发现,用0.1-0.8 mmol .L-1的Zn2+、Cd2+ 和Cu2+ 分别处理拟南芥原生质体30 分钟, 以OTM值表示的原生质体DNA损伤量随重金属离子浓度的增加而递增; 相同浓度(0.5 mmol.L-1)的3种重金属离子相比, Zn2+对原生质体的遗传毒性明显低于Cu2+ 和Cd2+。综合原生质体活力和DNA损伤的单细胞凝胶电泳检测结果, 发现Zn2+对拟南芥原生质体的遗传毒性较低, 而Cd2+ 和Cu2+的遗传毒性较高。本研究建立的拟南芥原生质体实验体系, 结合运用单细胞凝胶电泳技术, 能够快速、灵敏地检测重金属对植物细胞的遗传毒性。

Heavy Metal-induced DNA Damage in Arabidopsis thaliana Protoplasts Measured by Single-cell Gel Electrophoresis

In the present research, we established an Arabidopsis protoplast experimental system to study toxicity and DNA damage caused by heavy metals in plant cells. Protoplasts with high purity and viability isolated from mature leaves of 4-week-old Arabidopsis thaliana were used as experimental material. Three kinds of heavy metals—zinc (Zn2+), copper (Cu2+) and cadmium (Cd2+)—inducing toxicity and DNA damage in protoplasts were investigated. Cell survival rate was decreased in a time- and dosedependent fashion with the three metals. Zn2+ exposure at all concentrations induced a smaller and slower decrease in cell survival rate than with Cu2+ and Cd2+ exposure. DNA damage measured by single-cell gel electrophoresis was induced by Zn2+, Cu2+ and Cd2+ at 0.1-0.8 mmol.L-1, with significant increases in olive tail moments in all treated samples of protoplasts. As compared with Zn2+ exposure, Cu2+ and Cd2+ exposure at a similar concentration induced more severe DNA damage in protoplasts. Heavy metalinduced DNA damage was dose and time dependent. Thus, the heavy metals Cu2+ and Cd2+ are more cytotoxic and genotoxic than Zn2+. Use of single-cell gel electrophores is in the Arabidopsis protoplast experimental system is a fast and sensitive method for detecting genotoxicity caused by heavy metals.