Naseeb Samina, Ames Ryan M, Delneri Daniela, Lovell Simon C
School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Oxford Road, Manchester M13 9PT, UK.
School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Oxford Road, Manchester M13 9PT, UK
Proc Biol Sci. 2017 Aug 30;284(1861). doi: 10.1098/rspb.2017.1393.
Duplication of genes or genomes provides the raw material for evolutionary innovation. After duplication a gene may be lost, recombine with another gene, have its function modified or be retained in an unaltered state. The fate of duplication is usually studied by comparing extant genomes and reconstructing the most likely ancestral states. Valuable as this approach is, it may miss the most rapid evolutionary events. Here, we engineered strains of carrying tandem and non-tandem duplications of the singleton gene to monitor (i) the fate of the duplicates in different conditions, including time scale and asymmetry of gene loss, and (ii) the changes in fitness and transcriptome of the strains immediately after duplication and after experimental evolution. We found that the duplication brings widespread transcriptional changes, but a fitness advantage is only present in fermentable media. In respiratory conditions, the yeast strains consistently lose the non-tandem gene copy in a surprisingly short time, within only a few generations. This gene loss appears to be asymmetric and dependent on genome location, since the original copy and the tandem duplicate are retained. Overall, this work shows for the first time that gene loss can be extremely rapid and context dependent.
基因或基因组的复制为进化创新提供了原材料。基因复制后，可能会丢失、与另一个基因重组、其功能发生改变或保持不变。通常通过比较现存基因组并重建最可能的祖先状态来研究复制的命运。尽管这种方法很有价值，但它可能会错过最快速的进化事件。在这里，我们构建了携带单拷贝基因串联和非串联重复的菌株，以监测（i）在不同条件下重复基因的命运，包括基因丢失的时间尺度和不对称性，以及（ii）复制后和实验进化后菌株的适应性和转录组变化。我们发现，基因复制会带来广泛的转录变化，但只有在可发酵培养基中才存在适应性优势。在呼吸条件下，酵母菌株在短短几代内就会在惊人的短时间内持续丢失非串联的基因拷贝。这种基因丢失似乎是不对称的，并且依赖于基因组位置，因为原始基因拷贝和串联重复拷贝会保留下来。总体而言，这项工作首次表明基因丢失可能极其迅速且依赖于环境。
