Mahmoud J, Fossett N G, Arbour-Reily P, McDaniel M, Tucker A, Chang S H, Lee W R
Institute for Mutagenesis, Louisiana State University, Baton Rouge 70803-1725.
Environ Mol Mutagen. 1991;18(3):157-60. doi: 10.1002/em.2850180303.
The mutational spectrum for 28 X-ray induced mutations and 2 spontaneous mutations, previously determined by genetic and cytogenetic methods, consisted of 20 multilocus deficiencies (19 induced and 1 spontaneous) and 10 intragenic mutations (9 induced and 1 spontaneous). One of the X-ray induced intragenic mutations was lost, and another was determined to be a recombinant with the allele used in the recovery scheme. The DNA sequence of two X-ray induced intragenic mutations has been published. This paper reports the results of DNA sequence analysis of the remaining intragenic mutations and a summary of the X-ray induced mutational spectrum. Only one of the X-ray induced mutations is a single base change, a C to G transversion (AdhnLA80). Therefore, the mutational spectrum of X-ray induced mutations consists predominantly of deletions that are observed to range in size from two base pairs to deletions of a large number of loci as determined by genetic complementation analysis. The combination of DNA sequence analysis with genetic complementation analysis shows a continuous distribution in size of deletions rather than two different types of mutations consisting of deletions and "point mutations." Sequencing is shown to be essential for detecting intragenic deletions. Of particular importance for future studies is the observation that all of the intragenic deletions consist of a direct repeat adjacent to the break-point with one of the repeats deleted.
先前通过遗传和细胞遗传学方法确定的28个X射线诱导突变和2个自发突变的突变谱，包括20个多位点缺失（19个诱导型和1个自发型）和10个基因内突变（9个诱导型和1个自发型）。其中一个X射线诱导的基因内突变丢失了，另一个被确定为与回收方案中使用的等位基因的重组体。两个X射线诱导的基因内突变的DNA序列已经发表。本文报告了其余基因内突变的DNA序列分析结果以及X射线诱导突变谱的总结。X射线诱导的突变中只有一个是单碱基变化，即C到G的颠换（AdhnLA80）。因此，X射线诱导突变的突变谱主要由缺失组成，通过遗传互补分析确定，这些缺失的大小范围从两个碱基对到大量位点的缺失。DNA序列分析与遗传互补分析的结合显示缺失大小呈连续分布，而不是由缺失和“点突变”组成的两种不同类型的突变。测序对于检测基因内缺失至关重要。对于未来的研究特别重要的是观察到所有基因内缺失都由与断点相邻的直接重复序列组成，其中一个重复序列被删除。
