Mechanisms of Recurrent, Parallel Loss of X/Y Pairing and Recombination at Meiosis in Voles

描述（由申请人提供）：我提出了一个培训计划，这将为我在进化基因组学领域的独立研究生涯做准备。我在威斯康星州-麦迪逊大学遗传学实验室获得了博士学位，因为我在哺乳动物物种全球重组率差异的遗传和进化基础方面的工作。然后，我在华盛顿大学基因组科学系完成了为期2年的博士后研究，在那里我获得了大量的经验和熟练的大型基因组数据集的计算分析。通过拟议的培训计划，我将扩大我的实验技能集，包括基因组文库的构建，不同的细胞遗传学方法，并在哺乳动物模型系统中的候选基因的功能分析。我提出了一个为期5年的研究计划，包括为期2年的有组织的指导和培训阶段的生物复杂性倡议在北卡罗来纳州州立大学（NCSU），随后的3年研究阶段作为一个独立的调查员。 拟议的培训计划将利用尖端的测序技术和创新的方法进行染色体可视化，以阐明田鼠（田鼠属）中假常染色体区域（PAR）的复发性变性和丢失的机制。这项研究将借鉴不同的研究领域，包括基因组学，进化生物学和细胞遗传学。Trudy Mackay博士，William Neal Reynolds和杰出的大学遗传学教授，将担任我科学发展的主要导师。麦凯博士以其在进化和定量遗传学方面的工作而闻名于世，并拥有令人印象深刻的成功学生和博士后记录，这证明了她对培训年轻研究人员的承诺和热情。大卫Threadgill博士，教授和遗传学系主任在NCSU，将提供在小鼠功能遗传学的具体指示。马修·布林博士和丽莎·麦格劳博士都在NCSU，他们将分别提供细胞遗传学和田鼠遗传学方面的重点指导。教师研究兴趣的显着广度和他们的重叠与拟议的培训计划的智力和实验重点，使NCSU进行本研究的指导阶段的最佳场所。哺乳动物PAR促进减数分裂时异配子性染色体之间的配对、联会和重组。这些过程对于性染色体的分离是不可或缺的。在PAR中不能启动配对或重组可导致生精失败、不育和性染色体非整倍体，包括人类的特纳和克兰菲尔特染色体异常。尽管其重要的减数分裂功能，PAR是结构动态的，迅速演变，甚至已经完全失去了一些特殊的哺乳动物物种。田鼠（属田鼠）显示特别令人兴奋的趋势，在最近的PAR演变。在整个田鼠发生过程中，有证据表明减数分裂时X/Y染色体配对的平行丢失≥3个，包括多个密切相关的物种配对，有或没有减数分裂性染色体关联。我建议研究这些反复出现的进化事件，以解决3个具体问题：1。是什么样的结构和序列水平的变化促使这些田鼠谱系沿着PAR退化和丧失？我建议细胞遗传学检测和基因组序列比较密切相关的田鼠物种和不减数分裂X/Y配对和重组来回答这个问题。 2.不成对的非交叉性染色体如何在减数分裂中可靠地分离？我建议细胞学研究与减数分裂蛋白的定位模式，以确定候选的非交叉分离基因的性染色体动态。3.在田鼠中鉴定的候选X/Y分离基因是否挽救了具有PAR配对强制性要求的生物体中的性染色体分离缺陷，这些PAR配对在整个区域内具有破坏性突变？我将使用性染色体非整倍体频率较高的小鼠模型进行这些功能测试。多个，独立的事件的PAR损失整个田鼠发育的可用性提出了一个合理的过渡之间的指导阶段，重点解剖的基础上，在一个物种集的X/Y配对损失，和一个独立的调查阶段，建立在此培训，以确定PAR降解和性染色体分离的机制，在其他田鼠物种。拟议的研究计划将为PAR进化和减数分裂中性染色体分离的机制提供关键见解，并对了解人类性染色体非整倍性的发生具有潜在的临床影响。

DESCRIPTION (provided by applicant): I am proposing a training program that will prepare me for an independent research career in the field of evolutionary genomics. I received my PhD from the Laboratory of Genetics at the University of Wisconsin- Madison for my work on the genetic and evolutionary basis of mammalian species differences in global recombination rate. I then completed a 2-year postdoc in the Department of Genome Sciences at the University of Washington where I acquired considerable experience and proficiency in the computational analysis of large genomic datasets. Through the proposed training program, I will expand my experimental skill set to include genomic library construction, diverse cytogenetic methods, and functional analyses of candidate genes in mammalian model systems. I propose a 5-year research program composed of a 2-year phase of organized mentorship and training in the Initiative for Biological Complexity at North Carolina State University (NCSU), followed by a 3-year research phase as an independent investigator. The proposed training program will leverage cutting-edge sequencing technologies and innovative methods for chromosome visualization to elucidate the mechanisms of recurrent degeneration and loss of the pseudoautosomal region (PAR) in voles (genus Microtus). This research will draw on diverse research fields, including genomics, evolutionary biology, and cytogenetics. Dr. Trudy Mackay, William Neal Reynolds and Distinguished University Professor of Genetics, will act as the primary mentor for my scientific development. Dr. Mackay is a world-renowned for her work in evolutionary and quantitative genetics, and has an impressive record of successful students and postdocs as a testament to her commitment and enthusiasm for training young investigators. Dr. David Threadgill, Professor and head of the Department of Genetics at NCSU, will provide specific instruction in mouse functional genetics. Dr. Matthew Breen and Dr. Lisa McGraw, both at NCSU, will provide focused mentoring in cytogenetics and vole genetics, respectively. The remarkable breadth of faculty research interests and their overlap with the intellectual and experimental foci of the proposed training program make NCSU the optimal place for conducting the mentored phase of this research. The mammalian PAR promotes pairing, synapsis, and recombination between the heterogametic sex chromosomes at meiosis. These processes are integral to proper sex chromosome segregation. Failure to initiate pairing or recombination in the PAR can lead to spermatogenic failure, infertility, and sex chromosome aneuploidy, including Turner and Kleinfelter Syndromes in humans. Despite its important meiotic function, the PAR is structurally dynamic, rapidly evolving, and has even been completely lost in several exceptional mammalian species. Voles (genus Microtus) display particularly exciting trends in recent PAR evolution. Across the vole phylogeny, there is evidence for ≥3 parallel losses of X/Y chromosome pairing at meiosis, including multiple closely related species pairs with and without meiotic sex chromosome associations. I propose to study these recurrent evolutionary episodes to address 3 specific questions: 1. What structural and sequence-level changes precipitated the degeneration and loss of the PAR along these vole lineages? I propose cytogenetic assays and genome sequence comparisons between closely related vole species with and without meiotic X/Y pairing and recombination to answer this question. 2. How do unpaired, achiasmate sex chromosomes reliably segregate at meiosis? I propose cytological studies linking sex chromosome dynamics with the localization patterns of meiotic proteins to identify candidate achiasmate segregation genes. 3. Do candidate X/Y segregation genes identified in voles rescue sex chromosome segregation defects in organisms with obligate requirements for PAR pairing that harbor disruptive mutations across the region? I will carry out these functional tests using a mouse model with a high frequency of sex chromosome aneuploidy. The availability of multiple, independent episodes of PAR loss across the vole phylogeny presents a logical transition between a mentored phase focused on dissecting the basis of X/Y pairing loss in one species set, and an independent investigator phase that builds on this training to determine the mechanisms of PAR degradation and sex chromosome segregation in other vole species. The proposed research program will provide key insights into the mechanisms of PAR evolution and sex chromosome segregation at meiosis, with potential clinical consequences for understanding the genesis of sex chromosome aneuploidies in humans.