Schy W E, Plewa M J
Environ Mutagen. 1985;7(2):155-62. doi: 10.1002/em.2860070204.
We analyzed the kinetics of mutation induction at the yg2 locus in Zea mays by N-ethyl-N-nitrosourea (ENU). ENU concentrations ranged from 0.1 to 10.7 mM and a linear, concentration-dependent response was observed for the induction of yg2 sectors in leaf 4 and leaf 5. For both leaf 4 and leaf 5 ENU exhibited one-hit kinetics consistent with either a point-mutational or chromosome-breakage mechanism of mutation induction. The mean induced mutation rate/mM ENU for the combined leaf 4 and leaf 5 data was 6.77 X 10(-4) mutations/locus/mM ENU. This value was used to compare the mutagenic effectiveness of ENU with ethyl methanesulfonate (EMS) and to calculate a rad equivalent for ENU. ENU was found to be 3.8-fold more effective than EMS. Based on their respective chemical reactivities with DNA, we propose that ENU predominantly induces point mutations at the yg2 locus. One rad of gamma radiation induced the same rate of mutation as an 8-hr exposure to a 6.71 X 10(-6) M concentration of ENU at 20 degrees C.
我们分析了N-乙基-N-亚硝基脲（ENU）对玉米yg2位点的诱变动力学。ENU浓度范围为0.1至10.7 mM，在第4叶和第5叶中观察到yg2扇形区域的诱导呈线性、浓度依赖性反应。对于第4叶和第5叶，ENU均表现出单hit动力学，这与点突变或染色体断裂的诱变机制一致。第4叶和第5叶综合数据的平均诱变率/ mM ENU为6.77×10(-4) 突变/基因座/ mM ENU。该值用于比较ENU与甲磺酸乙酯（EMS）的诱变效力，并计算ENU的拉德当量。发现ENU的效力比EMS高3.8倍。基于它们与DNA的各自化学反应性，我们提出ENU主要在yg2位点诱导点突变。一拉德的γ辐射诱导的突变率与在20℃下暴露于6.71×10(-6) M浓度的ENU 8小时相同。
