突变是进化最原始的材料。早在达尔文时代,他就已经认识到进化取决于个体间的遗传差异:那些能够更好地适应环境的物种才能更好的将基因传递到下一代。只有发生新的突变形成新的变种,物种才能进化。
据最近一项发表于Science杂志的研究报告,德国马克斯普朗克发育生物学研究所和印第安纳大学的研究人员首次成功地直接测量出植物中出现新突变的速度。这项发现阐明最基本的进化过程。
该课题组对5种拟南芥(Arabidopsis thaliana)品系进行研究,拟南芥繁殖30代,研究人员再将最后一代拟南芥的基因组和其第一代拟南芥的基因组进行比较,寻找出其中的遗传差异。
研究发现,拟南芥每一代基因组中任何一个碱基发生突变的可能性为一点四亿分之一。为了尽量减小检测误差寻找真正的新突变,研究人员对每个基因组的每个碱基重复检查约30次。虽然每一株植物出现新突变的可能性似乎很小,但如果考虑到突变整个物种的基因组中的出现的可能性,很明显,该物种的基因组是易变的。
除了测出物种中新突变出现的速率,该研究还表明,基因组的各个部分发生突变的可能性并不相同。此外,研究人员还更精确的计算出新物种何时形成。(生物谷Bioon.com)
相关基因组变异研究:
Nature:大肠杆菌(E. coli)基因组演化的速度和模式
Nature Gene:细菌基因组正在快速进化
Nature:生物遗传突变普遍机制
生物谷推荐原始出处:
Science 1 January 2010: DOI: 10.1126/science.1180677
The Rate and Molecular Spectrum of Spontaneous Mutations in Arabidopsis thaliana
Stephan Ossowski,1,* Korbinian Schneeberger,1,* José Ignacio Lucas-Lledó,2,*, Norman Warthmann,1 Richard M. Clark,3 Ruth G. Shaw,4 Detlef Weigel,1, Michael Lynch2
To take complete advantage of information on within-species polymorphism and divergence from close relatives, one needs to know the rate and the molecular spectrum of spontaneous mutations. To this end, we have searched for de novo spontaneous mutations in the complete nuclear genomes of five Arabidopsis thaliana mutation accumulation lines that had been maintained by single-seed descent for 30 generations. We identified and validated 99 base substitutions and 17 small and large insertions and deletions. Our results imply a spontaneous mutation rate of 7 x 10–9 base substitutions per site per generation, the majority of which are G:CA:T transitions. We explain this very biased spectrum of base substitution mutations as a result of two main processes: deamination of methylated cytosines and ultraviolet light–induced mutagenesis.
1 Department of Molecular Biology, Max Planck Institute for Developmental Biology, 72076 Tübingen, Germany.
2 Department of Biology, Indiana University, Bloomington, IN 47405, USA.
3 Department of Biology, University of Utah, Salt Lake City, UT 84112, USA.
4 Department of Ecology, Evolution, and Behavior, University of Minnesota, St. Paul, MN 55108, USA.