Andersson D I, Slechta E S, Roth J R
Department of Biology, University of Utah, Salt Lake City, UT 84112, USA.
Science. 1998 Nov 6;282(5391):1133-5. doi: 10.1126/science.282.5391.1133.
Adaptive mutability is the apparent alteration in specificity or rate of mutability seen in bacteria during stress. A model is proposed by which gene amplification during selective growth can give the appearance of adaptive mutability without requiring any change in mutability. The model is based on two assumptions, that a mutant lac locus with residual function allows growth if its copy number is increased, and that true reversion events are made more likely by replication of chromosomes with many copies of the locus. Apparent directed mutability, its recombination requirement, and its apparent independence of cell growth are all accounted for by the model. Evidence is provided for the required residual function and gene amplification.
适应性突变是指细菌在应激期间出现的特异性或突变率的明显改变。本文提出了一个模型，通过该模型，选择性生长期间的基因扩增可产生适应性突变的表象，而无需突变率发生任何改变。该模型基于两个假设：一是具有残余功能的突变型乳糖操纵子位点，如果其拷贝数增加则允许生长；二是具有多个该位点拷贝的染色体进行复制会使真正的回复突变事件更有可能发生。该模型解释了明显的定向突变、其重组需求以及其明显的细胞生长独立性。文中提供了所需的残余功能和基因扩增的证据。
