Mutational mechanisms underlying mouse mosaicism

基因组通常被称为蓝图，但这种单一计划的图像无法捕捉生物体一生中基因组结构和序列的持续变化。突变研究的最新证据表明，从头突变的发生率比以前认为的更高，对基因组格局的影响也更大。发育是诱变的关键时期，个体组织和细胞在不同时期受到不同程度的影响。我的研究小组试图通过研究成年小鼠组织和细胞中新生突变的负荷来了解正常发育的突变特征的起源和机制。小鼠为哺乳动物基因组的突变机制提供了一个很好的模型，并且可以在充分研究遗传背景的情况下研究任何组织。我和我的学生在使用基因组平台检查小鼠基因组中493290个多态位点的点突变以及通过分析基因组中分布的915519个位点的拷贝数来检测缺失和重复方面具有专业知识。我们使用这个基因组学平台在小家鼠广泛遗传多样性的进化研究中检测单核苷酸变异和拷贝数变异基因组。我们现在提议在C57BL/6J （B6）近交系小鼠的三个家族的个体（父母和三个儿子）的一组组织中检测新突变的负荷，作为参考遗传背景。我们选择了具有不同发育历史的体细胞组织，并在精子发育的两个阶段对男性生殖细胞进行了分析。我们建议对预测与杂合性相关的突变率较高的三个B6D2杂交小鼠家族重复我们的研究。由于我们的遗传学平台偏向于分析基因组非基因区域的点突变，我们提出了全外显子组测序来检测基因组蛋白质编码区域的新生突变。我们的研究将记录成年小鼠个体组织中新突变的数量和性质，并对基因组杂合性、发育历史和编码序列的影响进行具体检查。我们的数据为正常小鼠发育过程中出现的体细胞嵌合体的程度和性质提供了一个基线，这将用于生物监测研究，以了解与环境诱变剂相关的突变机制，并与基因组完整性受损的小鼠遗传背景进行比较，以了解基因组维持机制。我们的研究是理解个体正常遗传多样性机制的基础。研究生和本科生将获得对学术机构、研究机构和政府机构的研究有价值的小鼠基因组变异分析的技术和计算专业知识。

A genome is often called a blueprint, but this image of a single plan fails to capture the continuous change occurring in both the structure and the sequence of a genome within an organism over a lifespan. Recent evidence in mutation research reveals that de novo mutations occur at higher rates and with greater impact on the genome landscape than thought previously. Development is a critical period of mutagenesis during which individual tissues and cells are affected at different times and to different degrees. My research team seeks to understand the origins and mechanisms of mutation characteristic of normal development by investigating the load of de novo mutations in tissues and cells of the adult mouse. Mice provide an excellent model of the mutational mechanisms in mammalian genomes and enable study of any tissue in the context of well studied genetic backgrounds. My students and I have expertise using a genomic platform to examine point mutations at 493,290 polymorphic sites in the mouse genome and to detect deletions and duplications through assay of copy number at 915,519 sites distributed across the genome. We used this genomics platform to detect single nucleotide variants and copy number variants genome wide in an evolutionary study of extensive genetic diversity in Mus musculus. We now propose to examine the load of new mutations in a panel of tissues in individuals (parents and three sons) of three families of C57BL/6J (B6) inbred mice, a reference genetic background. We selected somatic tissues with different developmental histories and we included analysis of male germ cells at two points in sperm development. We propose to repeat our study for three families of hybrid B6D2 mice predicted to have higher rates of mutation associated with heterozygosity. Since our genetics platform is biased in analyzing point mutations in nongenic regions of the genome, we propose whole exome sequencing to detect de novo mutations in protein coding regions of the genome. Our research will document the number and nature of new mutations in individual tissues of adult mice with specific examination of the influences of genomic heterozygosity, developmental history and coding sequence. Our data provide a baseline of the degree and nature of somatic mosaicism arising with normal mouse development that will be used in biomonitoring studies for understanding mutational mechanisms associated with environmental mutagens and in comparisons with mouse genetic backgrounds with compromised genome integrity to understand mechanisms of genome maintenance. Our research is fundamental to understanding mechanisms contributing to the normal genetic diversity that arises within an individual. Graduate and undergraduate students will gain technical and computational expertise in analysis of mouse genome variation valuable to research in academic institutions, research institutes and government agencies.