Vogel E W, Nivard M J, Zijlstra J A
Department of Radiation Genetics and Chemical Mutagenesis, Leiden, The Netherlands.
Mutat Res. 1991 Sep-Oct;250(1-2):291-8. doi: 10.1016/0027-5107(91)90184-p.
A set of six Drosophila strains was developed, by inducing by chemical treatment with N-ethyl-N-nitrosourea (ENU) new white and, in some strains, yellow mutations in 3 wild-type (WT) and 3 insecticide-resistant (IR) populations. These strains were previously shown to vary with regard to contents and inducibility of microsomal oxidative enzymes (Zijlstra et al., 1984). In this pilot study results from a first evaluation of these strains in somatic mutation experiments are reported, using as genotoxins an aromatic amine (2-naphthylamine, 2-NA), one substituted (9,10-dimethylanthracene, DA) and one non-substituted (benzo[a]pyrene, BP) polycyclic aromatic hydrocarbon. Developing larvae heterozygous for white were chronically exposed to three different exposure doses of each carcinogen. Adult females were inspected for the occurrence of mosaic light clones in their eyes, using the somatic mutation and recombination test (SMART). Evidence is presented indicating strong genotype-dependent variation in both spontaneous and chemically induced mutational and recombinational events in somatic cells of Drosophila. The spontaneous frequencies varied from 3.5% (Hikone-R), 4.3% (Berlin-K), 6.3% (Oregon-K), 9.1% (91-C), 20.5% (Haag-79) to 49.1% (91-R), corresponding to a 14-fold difference in spot frequencies between the two extremes. BP, DA and 2-NA were readily detectable in both Hikone-R (IR) and Oregon-K (WT), less so in 91-C (WT) and Haag-79 (IR), whereas the performance of strain Berlin-K (WT) was rather poor. The special problem with strain 91-R was the high frequency with which mosaic light spots occur not only in female genotypes heterozygous for white, but also in homozygous condition in the original stock. The up to 20-fold variation in induced spot frequencies between different genotypes poses questions for further investigations with respect to the genetic constitution of the various strains and the role of enzyme induction on somatic cell mutagenicity, which in this system is predominantly the result of mitotic recombination.
通过用N-乙基-N-亚硝基脲（ENU）进行化学处理，在3个野生型（WT）和3个抗杀虫剂（IR）种群中诱导产生了一组6个果蝇品系，产生了新的白色突变，在一些品系中还产生了黄色突变。这些品系先前已被证明在微粒体氧化酶的含量和诱导性方面存在差异（齐尔斯特拉等人，1984年）。在这项初步研究中，报告了在体细胞突变实验中对这些品系进行首次评估的结果，使用一种芳香胺（2-萘胺，2-NA）、一种取代的（9,10-二甲基蒽，DA）和一种未取代的（苯并[a]芘，BP）多环芳烃作为基因毒素。对白色基因杂合的发育中幼虫长期暴露于每种致癌物的三种不同暴露剂量下。使用体细胞突变和重组试验（SMART）检查成年雌性果蝇眼睛中镶嵌浅色克隆的出现情况。有证据表明，果蝇体细胞中自发和化学诱导的突变及重组事件存在强烈的基因型依赖性变异。自发频率从3.5%（彦根-R）、4.3%（柏林-K）、6.3%（俄勒冈-K）、9.1%（91-C）、20.5%（哈格-79）到49.1%（91-R）不等，对应于两个极端之间斑点频率14倍的差异。BP、DA和2-NA在彦根-R（IR）和俄勒冈-K（WT）中都很容易检测到，在91-C（WT）和哈格-79（IR）中检测到的较少，而柏林-K（WT）品系的表现相当差。91-R品系的特殊问题是，镶嵌浅色斑点不仅在白色基因杂合的雌性基因型中出现频率很高，而且在原始种群的纯合条件下也出现频率很高。不同基因型之间诱导斑点频率高达20倍的差异，就各种品系的遗传构成以及酶诱导对体细胞致突变性的作用提出了进一步研究的问题，在这个系统中，体细胞致突变性主要是有丝分裂重组的结果。
