de Serres F J
Center for Life Sciences and Toxicology, Chemistry and Life Sciences, Research Triangle Institute, Research Triangle Park, NC 27709.
Mutat Res. 1991 Jan;246(1):1-13. doi: 10.1016/0027-5107(91)90104-v.
There is considerable controversy in the literature concerning the nature of X-ray-induced specific-locus mutations in various experimental organisms. To investigate this problem in Neurospora crassa a series of experiments (Webber and de Serres, 1965) was performed to study the induction-kinetics of X-ray-induced mutation in the adenine-3 (ad-3) region of a two-component heterokaryon (H-12). Subsequent genetic analyses (de Serres, 1989a,b,c, 1990a), on a series of 832 mutants recovered in these experiments, have shown that 3 different classes of ad-3 mutants were recovered, namely gene/point mutations, multilocus deletions and multiple-site mutations. Complementation studies with a series of genetic markers that define 21 genetic loci in the ad-3 and immediately adjacent genetic regions have shown that ad-3 mutants classified as multilocus deletions result from the inactivation of a series of loci in the ad-3 and immediately adjacent regions of Linkage Group I, whereas multiple-locus mutations result from combinations of gene/point mutations and multilocus deletions. Analysis of the induction kinetics of these 3 different classes, after completion of the genetic characterization of all mutants (de Serres, 1990b) demonstrated that gene/point mutations increase linearly with X-ray dose, whereas multilocus deletions and multiple-site mutations increase as the square of X-ray dose. Further analysis of allelic complementation among the gene/point mutations at the ad-3B locus (de Serres, 1990c), demonstrated that the spectrum of complementation patterns was dose-dependent: complementing mutants with nonpolarized patterns decreased and noncomplementing mutations increased with increasing X-ray dose. There was little or no change with dose in the frequency of mutants with polarized patterns. In the present report, data from studies published previously have been utilized, along with additional data from the original X-ray experiments (12-5, 12-6, 12-7, and 12-10; see Webber and de Serres, 1965) to develop composite complementation maps of the X-ray-induced specific-locus mutations in the ad-3 and immediately adjacent regions as a function of X-ray dose. This analysis of the overall spectrum of X-ray-induced specific-locus mutations in the ad-3 region demonstrated marked dose-dependence and provides an explanation for the discrepancies in the literature with regard to specific-locus studies in different experimental organisms.
关于X射线在各种实验生物体中诱导的特定基因座突变的性质，文献中存在相当大的争议。为了在粗糙脉孢菌中研究这个问题，进行了一系列实验（韦伯和德塞雷斯，1965年），以研究X射线诱导的双组分异核体（H - 12）腺嘌呤-3（ad - 3）区域突变的诱导动力学。随后对在这些实验中获得的832个突变体进行的遗传分析（德塞雷斯，1989a、b、c，1990a）表明，回收了3种不同类型的ad - 3突变体，即基因/点突变、多位点缺失和多位点突变。用一系列定义ad - 3和紧邻遗传区域中21个遗传位点的遗传标记进行互补研究表明，归类为多位点缺失的ad - 3突变体是由于连锁群I的ad - 3和紧邻区域中一系列位点的失活所致，而多位点突变则是由基因/点突变和多位点缺失的组合引起的。在完成所有突变体的遗传特征分析后（德塞雷斯，1990b），对这3种不同类型的诱导动力学分析表明，基因/点突变随X射线剂量呈线性增加，而多位点缺失和多位点突变随X射线剂量的平方增加。对ad - 3B位点基因/点突变之间的等位基因互补的进一步分析（德塞雷斯，1990c）表明，互补模式的谱是剂量依赖性的：随着X射线剂量增加，具有非极化模式的互补突变体减少，非互补突变增加。具有极化模式的突变体频率随剂量变化很小或没有变化。在本报告中，利用了先前发表的研究数据，以及来自原始X射线实验（12 - 5、12 - 6、12 - 7和12 - 10；见韦伯和德塞雷斯，1965年）的额外数据，来绘制ad - 3和紧邻区域中X射线诱导的特定基因座突变的复合互补图谱，作为X射线剂量的函数。对ad - 3区域中X射线诱导的特定基因座突变的整体谱的这种分析表明了明显的剂量依赖性，并为不同实验生物体中特定基因座研究的文献差异提供了解释。
