The role of sister-chromatid cohesion in heterochromatin-mediated association of achiasmate homologues in Drosophila oocytes

智力价值：减数分裂是一种特殊类型的细胞分裂，是产生卵子和精子所必需的。每对同源染色体之间的物理连接对于它们在第一次减数分裂中的准确分离是必要的。如果没有建立或维持这种联系，同源基因可能会错误分离，导致非整倍体配子，在大多数情况下，无法存活的后代。因此，对确保适当同源关联的机制的分析将产生有关有性繁殖和物种繁殖的关键信息。正常情况下，减数分裂重组与姐妹染色单体凝聚力一起建立了一种物理连接，将每对同源染色体保持在一起，直到后期I。然而，一些生物利用了一种替代机制，确保未能重组的同源染色体对得到适当的分离。在果蝇卵母细胞中，非重组同系物的准确分离依赖于其着丝粒附近的异染色质。此外，首席研究员实验室最近的工作揭示了姐妹染色单体凝聚力和异染色质介导的同源物配对之间意想不到的联系。这些数据表明，姐妹染色单体凝聚蛋白不仅维持重组同源物的联系，而且在促进非重组同源物的物理联系中发挥重要作用。这个项目将通过完成以下三个目标来定义姐妹染色单体凝聚力和异染色质在促进非重组同源物准确分离方面的关系：1)检验粘附素复合体促进非重组同源物异染色质介导配对的假设；2)探索粘附素调节因子WAPL在促进非重组同源物关联方面的作用；3)测试异染色质蛋白HP1促进非重组同源物准确分离的假设。这项研究将通过阐明在雌性黑腹果蝇减数分裂过程中确保非重组染色体适当分离的机制来扩大对这一基本生物学过程的理解。鉴于着丝粒配对在分裂酵母和芽生酵母中对非重组染色体的忠实分离以及姐妹染色单体凝聚力在进化上是保守的，这些结果也可能产生关于同源关联和其他生物中非重组染色体分离的有价值的信息。此外，该项目将把本科生和研究生的研究和教育结合起来。学生将参与研究的方方面面，包括实验设计、执行和数据分析。每一项目标所采用的方法很容易使本科生在技术和智力两个层面上充分参与。本科生和研究生都将参加每周的实验室会议/期刊俱乐部。学习有效地交流他们的研究和想法将是他们培训的重要部分。在过去的11年里，首席调查员指导了22名本科生和5名博士生。研究小组的规模较小，有利于首席研究员与实验室每个成员的互动，以及成员之间的广泛互动。此外，指导本科生是研究生培养的重要组成部分。

Intellectual Merit: Meiosis is a specialized type of cell division that is required for the production of eggs and sperm. A physical connection between each pair of homologous chromosomes is necessary for their accurate segregation during the first meiotic division. If this association is not established or maintained, homologues can missegregate resulting in aneuploid gametes and in most cases, inviable offspring. Therefore, analysis of the mechanisms that ensure proper homologue association will yield critical information about sexual reproduction and species propagation. Normally, meiotic recombination in conjunction with sister-chromatid cohesion establishes a physical connection that holds each pair of homologous chromosomes together until anaphase I. However, some organisms utilize an alternative mechanism that ensures the proper segregation of homologue pairs that fail to recombine. In Drosophila melanogaster (fruit fly) oocytes, accurate segregation of non-recombinant homologues depends on heterochromatin near their centromeres. In addition, recent work in the principal investigator's laboratory has uncovered an unexpected link between sister-chromatid cohesion and heterochromatin-mediated pairing of homologues. These data suggest that sister-chromatid cohesion proteins not only maintain the association of recombinant homologues but also play an important role in promoting the physical association of non-recombinant homologues. This project will define the relationship between sister-chromatid cohesion and heterochromatin in promoting accurate segregation of non-recombinant homologues by completing the following three objectives: 1) Test the hypothesis that the cohesin complex promotes heterochromatin-mediated pairing of non-recombinant homologues; 2) Explore the role of the cohesin regulator WAPL in promoting the association of non-recombinant homologues; 3) Test the hypothesis that the heterochromatin protein HP1 promotes the accurate segregation of non-recombinant homologues.Broader Impacts: Accurate chromosome segregation during meiosis is essential for sexual reproduction. This research will expand the understanding of this fundamental biological process by elucidating the mechanisms that ensure proper segregation of non-recombinant chromosomes during female meiosis in Drosophila melanogaster. Given that centromere pairing plays a role in the faithful segregation of non-recombinant chromosomes in both fission and budding yeast and that sister-chromatid cohesion is evolutionarily conserved, these results may also yield valuable information about homologue association and the segregation of non-recombinant chromosomes in other organisms. In addition, this project will integrate research and education at both the undergraduate and graduate levels. Students will be involved in all aspects of the research involved including experimental design, execution and data analysis. The methodology used for each of the objectives lends itself easily to the full participation of undergraduates at both the technical and intellectual level. Both undergraduates and graduate students will attend weekly lab meetings/journal clubs. Learning to effectively communicate their research and ideas will be an essential part of their training. In the past 11 years, the principal investigator has mentored 22 undergraduates and 5 Ph.D. students. The small size of the research group facilitates interaction of the principal investigator with each member of the lab as well as extensive interaction among members. In addition, mentoring undergraduates represents an important component of graduate student training.