Anderson P
Department of Genetics, University of Wisconsin, Madison 53706, USA.
Methods Cell Biol. 1995;48:31-58.
Choosing the right mutagen means selecting the right combination of mutagen efficiency and mutagen specificity. For mutagen efficiency, nothing beats EMS. It is extremely potent, it is easy to use, and its mutational specificity is well documented. If mutations other than G/C-->A/T transitions are desired, mutagens other than EMS must be used. Based on initial observations, ENU appears to be as efficient as EMS. Work with other organisms predicts that ENU will yield a wider variety of transitions and transversions than EMS. If this proves to be true, ENU will become an important mutagen for routine genetic analysis. For investigators wanting large multigene deletions, gamma irradiation, UV irradiation, formaldehyde, and DEO are the mutagens of choice. Gamma irradiation yields the highest frequency of events by far, but may also yield more complex rearrangements. Based on limited information, UV irradiation, formaldehyde, and DEO appear to be effective deletion mutagens. Of the three, UV appears to be the most efficient. For investigators wanting small intragenic deletions, TMP appears most effective. TMP is not very potent, but a large proportion of TMP-induced unc-22 mutations are small deletions. Hopefully this will be true of all genes. For investigators wanting other types of genome rearrangements (e.g., translocations, crossover suppressors), gamma irradiation (or possibly X irradiation) is effective. For transposon insertions, mut-2 (especially strain TR679) provides the highest possible frequency of events. Because mut-2 activates several families of transposons, it yields insertions in genes that are poor targets for Tc1. Manipulating a strain with such high frequencies of spontaneous mutations, however, can be problematical (see above). For Tc1-specific events, mut-6 (strain RW7097) is the best choice. It provides frequencies comparable to those of Bergerac, but its Tc1 copy number is much lower. A reasonable strategy for spontaneous mutagenesis is to use TR679 only if mutants are not obtained in strains with lower levels of activity (e.g., MT3126 or RW7097).
选择合适的诱变剂意味着要选择诱变效率和诱变特异性的正确组合。就诱变效率而言，没有什么能比甲基磺酸乙酯（EMS）更好。它极其有效，易于使用，其诱变特异性也有充分的文献记载。如果需要G/C→A/T转换以外的突变，则必须使用EMS以外的诱变剂。基于初步观察，N-乙基-N-亚硝基脲（ENU）似乎与EMS一样有效。对其他生物体的研究预测，ENU将比EMS产生更多种类的转换和颠换。如果这被证明是真的，ENU将成为常规遗传分析的重要诱变剂。对于想要获得大型多基因缺失的研究人员来说，γ射线、紫外线、甲醛和二乙基亚硝基胺（DEO）是首选的诱变剂。γ射线产生的事件频率迄今为止最高，但也可能产生更复杂的重排。基于有限的信息，紫外线、甲醛和DEO似乎是有效的缺失诱变剂。在这三种中，紫外线似乎是最有效的。对于想要获得小的基因内缺失的研究人员来说，三甲苯磷酸酯（TMP）似乎最有效。TMP的效力不是很强，但TMP诱导的unc-22突变中有很大一部分是小缺失。希望所有基因都是如此。对于想要获得其他类型基因组重排（如易位、交叉抑制子）的研究人员来说，γ射线（或可能的X射线）是有效的。对于转座子插入，mut-2（特别是TR679菌株）能提供最高的事件频率。因为mut-2能激活几个转座子家族，它能在对Tc1来说是较差靶标的基因中产生插入。然而，处理具有如此高频率自发突变的菌株可能会有问题（见上文）。对于Tc1特异性事件，mut-6（RW7097菌株）是最佳选择。它提供的频率与Bergerac相当，但其Tc1拷贝数要低得多。自发诱变的一个合理策略是，只有在活性较低的菌株（如MT3126或RW7097）中未获得突变体时，才使用TR679。
