Steinkellner H, Mun-Sik K, Helma C, Ecker S, Ma T H, Horak O, Kundi M, Knasmüller S
Institute for Tumor Biology-Cancer Research, University of Vienna, Austria.
Environ Mol Mutagen. 1998;31(2):183-91.
The potential use of micronucleus assays in plants for the detection of genotoxic effects of heavy-metal ions was investigated. Three different plant systems were comparatively investigated in micronucleus tests with Tradescantia pollen mother cells (Trad MCN) and micronucleus tests with meristematic root tip cells of Allium cepa and Vicia faba (Allium/ Vicia MCN). As3+, Pb2+, Cd2+, Zn2+ caused a dose-dependent increase of MCN frequencies in all three test systems. Cu2+ gave consistently negative responses in all three tests; Zn2+ caused only a moderate, statistically not significant increase of MCN frequencies in Vicia. The ranking of genotoxic potencies in all three tests was in the descending order: As3+ > Pb2+ > Cd2+ > Zn2+ Cu2+. In experiments with Tradescantia, induction of MCN was observed in a concentration range between 1 and 10 mM, whereas in tests with root tip cells, higher concentrations (10-1,000 mM) were required to show significant effects. Further increase of the exposure levels caused toxic effects (reduction of root growth), cell division delays, and a decrease of MCN frequencies. Comparisons by linear regression analyses indicated that the sensitivity of the three bioassays for heavy metals decreases in the order: Trad MCN > Vicia root MCN > Allium root MCN. In further experimental series, a soil sample which contained high concentrations of the five metals and a control soil were investigated. Aqueous soil extracts induced only weak effects in Trad MCN tests and no effects in the root tip assays, whereas cultivation of the plants in the soils resulted in a pronounced induction of MCN in the Tradescantia system and moderate effects in Vicia and Allium. In conclusion, the results of the study indicate that the Trad MCN assay detects the genotoxic effects of heavy metals and can be used for biomonitoring metal-contaminated soils.
研究了植物微核试验在检测重金属离子遗传毒性效应方面的潜在用途。在紫露草花粉母细胞微核试验（Trad MCN）以及洋葱和蚕豆分生组织根尖细胞微核试验（洋葱/蚕豆MCN）中，对三种不同的植物系统进行了比较研究。As3+、Pb2+、Cd2+、Zn2+在所有三种测试系统中均导致微核频率呈剂量依赖性增加。Cu2+在所有三种测试中均始终给出阴性反应；Zn2+仅使蚕豆微核频率有适度增加，统计学上无显著意义。所有三种测试中遗传毒性强度的排序为：As3+ > Pb2+ > Cd2+ > Zn2+ > Cu2+。在紫露草实验中，在1至10 mM的浓度范围内观察到微核的诱导，而在根尖细胞测试中，需要更高浓度（10 - 1000 mM）才能显示出显著效果。暴露水平的进一步增加导致毒性效应（根生长减少）、细胞分裂延迟以及微核频率降低。线性回归分析比较表明，三种重金属生物测定法的灵敏度按以下顺序降低：Trad MCN > 蚕豆根MCN > 洋葱根MCN。在进一步的实验系列中，研究了一个含有高浓度这五种金属的土壤样品和一个对照土壤。土壤水提取物在Trad MCN测试中仅产生微弱影响，在根尖试验中无影响，而在土壤中种植植物导致紫露草系统中微核显著诱导，在蚕豆和洋葱中产生中等影响。总之，研究结果表明，Trad MCN测定法可检测重金属的遗传毒性效应，可用于生物监测金属污染土壤。
