Reams Andrew B, Roth John R
Department of Biological Sciences, California State University, Sacramento, California 95819-6077.
Department of Microbiology and Molecular Genetics, University of California, Davis, California 95616.
Cold Spring Harb Perspect Biol. 2015 Feb 2;7(2):a016592. doi: 10.1101/cshperspect.a016592.
Changes in gene copy number are among the most frequent mutational events in all genomes and were among the mutations for which a physical basis was first known. Yet mechanisms of gene duplication remain uncertain because formation rates are difficult to measure and mechanisms may vary with position in a genome. Duplications are compared here to deletions, which seem formally similar but can arise at very different rates by distinct mechanisms. Methods of assessing duplication rates and dependencies are described with several proposed formation mechanisms. Emphasis is placed on duplications formed in extensively studied experimental situations. Duplications studied in microbes are compared with those observed in metazoan cells, specifically those in genomes of cancer cells. Duplications, and especially their derived amplifications, are suggested to form by multistep processes often under positive selection for increased copy number.
基因拷贝数的变化是所有基因组中最常见的突变事件之一，也是最早已知其物理基础的突变类型之一。然而，基因复制的机制仍然不确定，因为形成速率难以测量，而且机制可能因基因组中的位置而异。本文将复制与缺失进行了比较，缺失在形式上似乎相似，但可以通过不同的机制以非常不同的速率产生。文中描述了评估复制速率和依赖性的方法以及几种提出的形成机制。重点放在了在广泛研究的实验情况下形成的复制上。将微生物中研究的复制与后生动物细胞中观察到的复制进行了比较，特别是癌细胞基因组中的复制。复制，尤其是其衍生的扩增，被认为是通过多步骤过程形成的，这些过程通常在对增加拷贝数的正选择下发生。
