The Rate and Molecular Spectrum of Spontaneous Mutations

描述(由申请人提供)： 突变过程最终决定了所有种群的遗传特征，因此与进化遗传学、遗传和遗传性疾病的一系列问题有关。然而，尽管突变是生物学的中心，但强大的技术障碍限制了我们对突变出现的速度及其影响的分子光谱的理解。这项拟议的研究利用新出现的突变检测技术来解决一些核心问题。首先，利用长期的突变积累系进行全基因组测序，我们将确定在广泛的真核微生物物种中自发产生突变(种系复制错误)的比率和全分子谱。这项工作将完成对突变率变异的系统发育调查(涉及约50个物种)，检验微生物真核生物具有极低突变率的假设，并有助于形成突变率进化的新的一般理论(漂移屏障假说)。其次，将一种新开发的方法应用于全部研究物种，我们将估计在将DNA转录为RNA过程中出现错误的速度。初步数据表明，这种瞬时误差的出现速度比复制过程中的速度高出几个数量级。如果得到证实，这将意味着很大一部分基因转录本包含错误；我们还将根据漂移屏障假说测试转录素和复制错误率是否以相同的方式扩展。第三，使用相同的方法，我们将在各种多细胞物种的几个组织中估计体细胞突变率，检验这样的突变率远远超过生殖系的假设。因为突变是所有遗传性遗传疾病和躯体获得性癌症的最终来源，所以这项工作的结果将对广泛的研究具有重要意义 与人类健康相关的问题。此外，这项研究中出现的无偏见的突变率和突变谱将为进化遗传学家在分子水平上关注自然变异的来源提供强大的资源。

DESCRIPTION (provided by applicant): The mutation process ultimately defines the genetic features of all populations, and hence has a bearing on the full range of issues in evolutionary genetics, inheritance, and genetic disorders. Yet, despite the centrality of mutation to biology, formidable technical barriers have constrained our understanding of the rate at which mutations arise and the molecular spectrum of their effects. The proposed research takes advantage of newly emergent technology for mutation detection to address a number of central issues. First, performing whole-genome sequencing with long-term mutation-accumulation lines, we will ascertain the rate and full molecular spectrum of spontaneously arising mutations (germline replication errors) in a wide range of eukaryotic microbial species. This work will complete a phylogenetically wide survey of mutation-rate variation (involving ~50 species), test the hypothesis that microbial eukaryotes have extraordinarily low mutation rates, and contribute to an emergent general theory on mutation-rate evolution (the drift-barrier hypothesis). Second, applying a newly developed method to the full set of study species, we will estimate the rate at which errors arise during transcription of DNA to RNA. Preliminary data suggest that such transient errors arise at rates several orders of magnitude higher than those during replication. If confirmed, this would imply that a large fraction of gene transcripts contain errors; and we will also test whether transcriptin and replication error rates scale in the same way in accordance with the drift-barrier hypothesis. Third, using the same method, we will estimate the somatic mutation rate in several tissues in a variety of multicellular species, testing the hypothesis that such rates greatly exceed those in the germline. Because mutations are the ultimate source of all inherited genetic disorders and of somatically acquired cancers, the results of this work will be of central relevance to a wide array of human-health related issues. In addition, the unbiased rates and spectra of mutation that emerge from this study will provide a powerful resource for evolutionary geneticists concerned with the sources of natural variation at the molecular level.