High Mutation Rates in the Mitochondrial Genomes of Daphnia pulex
High Mutation Rates in the Mitochondrial Genomes of Daphnia pulex
复制标题
DOI：
10.1093/molbev/msr243
复制
发表时间：
2012-02-01
影响因子：
10.7
通讯作者：
Cristescu, Melania E.
中科院分区：
文献类型：
--
作者：
Xu, Sen;Schaack, Sarah;Cristescu, Melania E.
尽管线粒体 DNA (mtDNA) 序列数据在群体遗传学和系统发育学中具有很大的用途，但描述线粒体突变过程的关键参数（例如突变变化的速率和谱）却很少基于直接估计。此外，物种内或谱系之间线粒体 DNA 突变过程的差异以及不同的繁殖策略仍然知之甚少。在本研究中，我们使用源自有性（循环孤雌生殖）和无性（专性孤雌生殖）谱系的水蚤突变积累（MA）系直接估计线粒体DNA突变率和谱。 82个有性和47个无性MA系的几乎完整的线粒体基因组序列显示，每代每个核苷酸的mtDNA突变率分别为1.37 x 10(-7)和1.73 x 10(-7)。水蚤 mtDNA 突变率是真核生物中最高的，其谱以插入和缺失为主（70%），这主要是由于同聚核苷酸片段中存在突变热点。对水蚤线粒体有效种群规模的最大似然估计表明，每代雌性会传播 5 到 10 个线粒体基因组拷贝。有性谱系和无性谱系之间的比较显示，突变率没有统计学差异，突变谱高度相似。
Despite the great utility of mitochondrial DNA (mtDNA) sequence data in population genetics and phylogenetics, key parameters describing the process of mitochondrial mutation (e.g., the rate and spectrum of mutational change) are based on few direct estimates. Furthermore, the variation in the mtDNA mutation process within species or between lineages with contrasting reproductive strategies remains poorly understood. In this study, we directly estimate the mtDNA mutation rate and spectrum using Daphnia pulex mutation-accumulation (MA) lines derived from sexual (cyclically parthenogenetic) and asexual (obligately parthenogenetic) lineages. The nearly complete mitochondrial genome sequences of 82 sexual and 47 asexual MA lines reveal high mtDNA mutation rate of 1.37 x 10(-7) and 1.73 x 10(-7) per nucleotide per generation, respectively. The Daphnia mtDNA mutation rate is among the highest in eukaryotes, and its spectrum is dominated by insertions and deletions (70%), largely due to the presence of mutational hotspots at homopolymeric nucleotide stretches. Maximum likelihood estimates of the Daphnia mitochondrial effective population size reveal that between five and ten copies of mitochondrial genomes are transmitted per female per generation. Comparison between sexual and asexual lineages reveals no statistically different mutation rates and highly similar mutation spectra.