Genetic dissection of trait variation between long-diverged mouse species

项目摘要/摘要 在地球上生命进化的40亿年里，有机体获得了令人惊叹的表型。 有些，比如狮子的鬃毛和蝴蝶的翅膀，纯粹的美丽吸引了我们的注意。其他人得到了我们 以一种非常不同的方式兴奋-它们与生物医学的相关性。生态学家已经将不同寻常的 植物和动物世界中的抗病和抗逆性特征，已经出现来解决类似的问题 对人类病人的影响。我们很想知道这些天然抗性表型的分子基础，所以 我们可以在生物医学的背景下设计药物来模仿它们。然而，最常见的情况是，我们知道一个 因为它是各自物种的一个定义特征，很久以前就获得了，以适应独特的 利基市场。现在，数百万年后的今天，这个物种通常已经失去了与其他物种的近亲杂交的能力 环境。这种生殖隔离是现有将基因类型映射到表型的工具的丧钟。 后者填补了现代遗传学文献的页面，依赖于重组后代的大面板 来自不同父母之间的交配。这些工具在研究不能交配形成的物种时毫无用处 子孙放在首位。 我们已经开发出一种新的策略来突破这个障碍，并绘制出性状变异的遗传基础图 在长期分化的物种之间。我们的方法始于一种可行但不育的种间杂交。在这 杂交种，在给定的基因上，我们引入突变来依次干扰这两个物种的两个等位基因。 父母。这些半合子突变体在背景方面是相同的，除了在靶基因上， 每个菌株都只表达来自双亲之一的野生型等位基因。因此，如果半合子与 对于感兴趣的性状，我们推断它一定是由于被操纵的功能等位基因的变异 地点。我们已经开创了一条基因组规模的管道，用于这种所谓的相互半合子测试，我们称之为 Rh-seq，使用酵母作为概念验证。在当前的提案中，我们描述了将RH-seq移植到 哺乳动物细胞。我们重点研究了一种很少被研究的小鼠物种，卡氏支原体，它可以再生 损伤后的中枢神经系统。我们在这项开创性研究中发现的基因将成为 中风和脑外伤患者的药物设计。我们的后生动物RH-seq方法将为 真核生物物种间性状变异的遗传解剖。

PROJECT SUMMARY/ABSTRACT Over the four billion years that life has evolved on this planet, organisms have acquired amazing phenotypes. Some, like lions' manes and butterflies' wings, capture our attention by their sheer beauty. Others get us excited in a very different way—their relevance to biomedicine. Ecologists have catalogued remarkable disease and stress resistance traits in the plant and animal worlds, which have arisen to solve problems similar to those in human patients. We'd love to know the molecular basis of these natural resistance phenotypes, so that we can design drugs to mimic them in the biomedical context. However, most often, we know about a given trait because it is a defining feature of its respective species, acquired long ago to adapt to a unique niche. Now, millions of years later, the species usually has lost the ability to interbreed with relatives in other environments. And this reproductive isolation is a death knell for existing tools to map genotype to phenotype. The latter, which fill the pages of the modern genetics literature, rely on big panels of recombinant progeny from matings between distinct parents. These tools are no use in the study of species that can't mate to form progeny in the first place. We have developed a new strategy to break through this roadblock, and map the genetic basis of trait variation between long-diverged species. Our approach starts with a viable, but sterile, interspecific hybrid. In this hybrid, at a given gene, we introduce mutations to disrupt each of the two alleles in turn from the two species parents. These hemizygote mutants are identical with respect to background, except that at the target gene, each strain expresses a wild-type allele from only one of the parents. As such, if the hemizygotes differ with respect to a trait of interest, we infer that it must be because of functional allelic variation at the manipulated site. We have pioneered a genome-scale pipeline for this so-called reciprocal hemizygosity test, which we call RH-seq, using yeast as proof of concept. In the current proposal we describe experiments to port RH-seq to mammalian cells. We focus on a little-studied mouse species, M. castaneus, which can regrow axons of the central nervous system after injury. The genes we find in this pioneering study will serve as a springboard for drug design for stroke and brain trauma patients. And our metazoan RH-seq approach will pave the way for the genetic dissection of trait variation between species across Eukarya.