Evolution of Meiotic Mechanisms in Divergent Cytological Environments

描述（由申请人提供）：减数分裂是所有有性生殖生物的基本过程。这一过程中的问题可能导致染色体分离错误，从而导致不育、死亡和唐氏综合症等疾病。许多减数分裂的蛋白质和元件在进化上是保守的，在精确的减数分裂机制上存在物种水平的差异，但关于这些不同的机制或相关蛋白质是如何进化的数据却非常少。我建议通过研究密切相关的二倍体和同源四倍体拟南芥的细胞学和功能分子遗传差异来解决新的减数分裂过程和相关蛋白是如何进化的问题。多倍体是研究这个问题的理想系统，因为在同源染色体数量加倍的环境中，减数分裂机制有很强的选择压力，以确保适当的配对、交叉和分离。为了对这些环境之间的差异进行分类，我建议对二倍体、天然同源四倍体和合成四倍体进行详细的细胞学研究。我还将通过转基因分析研究四倍体谱系中具有强选择特征的减数分裂相关蛋白的功能。在一项补充实验中，我将对合成的自体四倍体进行配子活力和遗传的人工选择实验

DESCRIPTION (provided by applicant): Meiosis is a fundamental process for all sexual reproducing organisms. Problems in this process can lead to chromosome mis-segregation, which can result in sterility, lethality, and diseases such as Down's syndrome. Many proteins and elements of meiosis are evolutionarily conserved, there is species level variation in the precise meiotic mechanisms, but there is remarkably little data on how these different mechanisms or the associated proteins have evolved. I propose to address the question of how a novel meiotic process and associated proteins evolve by studying cytological and functional molecular genetic differences between closely related diploid and autotetraploid Arabidopsis arenosa. Polyploidy is an ideal system to study this question, because there is strong selective pressure on the meiosis machinery to ensure proper pairing, crossing- over, and segregation in an environment with double the number of homologous chromosomes. To catalogue the differences between these environments, I propose to conduct a detailed cytological investigation of diploid, natural autotetraploid, and synthetic tetraploid lines. I will also investigate the function of meiosis related proteins with strong signatures of selection in the tetraploid lineage through transgenic analysis. In a complimentary experiment, I will conduct an artificial selection experiment on gamete viability in the synthetic autotetraploid and genetically map loci that ensure proper meiosis in the tetraploid.