KARYOGAMY AND CENTROSOME-DEPENDENT PROCESSES IN BUDDING YEAST

这个子项目是利用由NIH/NCRR资助的中心拨款提供的资源的许多研究子项目之一。子项目和调查员(PI)可能从另一个NIH来源获得了主要资金，因此可能会出现在其他CRISE条目中。列出的机构是针对中心的，而不一定是针对调查员的机构。在交配过程中，酿酒酵母细胞对交配信息素的梯度做出反应，以极化的方式彼此生长。在两个细胞相遇后，它们的壁在接触区域降解，它们的质膜融合成单个细胞。最终，两个核由微管组织中心(MTOCs)发出的微管连接起来，即纺锤体极体。通过微管电机驱动的过程，核被吸引到彼此之间。核膜在纺锤体极体附近典型地融合，形成单一的二倍体核。相应地，该模型系统很好地描述了细胞极化、膜融合、核运动和微管组织等几个基本的生物细胞过程。纺锤体及其相关的微管在整个核配子过程中特别重要，因为MTOCs对核迁移、融合和极性至关重要。先前的工作表明，完成核配子需要Kar9p、Kar3p和Kar1p蛋白(它们都是MTOCs的组成部分)。此外，Kar2p.核膜被膜上的Kar5p、Kar7p和Kar8p都是核膜的一部分，是核膜融合所必需的。电子显微镜，特别是半厚切片的电子断层扫描，已被证明对于研究MTOC相关过程是非常有价值的，因为它允许在单个细胞内从MTOC重建整个微管阵列。因此，电子断层扫描在核配子过程中的应用应该为了解MTOCs参与该系统的先前未知的过程提供深入的了解。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. During mating, S. cerevisiae cells respond to gradients of mating pheromone by growing toward one another in a polarized fashion. After two cells have met, their walls are degraded in the region of contact and their plasma membranes fuse to make a single cell. Eventually, the two nuclei become connected by microtubules that emanate from the microtubule organizing centers (MTOCs), i.e., the spindle pole bodies. The nuclei are drawn toward one another by a microtubule motor-driven process. The nuclear envelopes characteristically fuse in the vicinity of the spindle pole bodies, giving rise to a single diploid nucleus. Accordingly, several basic biological cell processes, e.g., cell polarization, membrane fusion, nuclear movement and microtubule organization are well represented by this model system. The spindle pole bodies and their associated microtubules are of particular importance throughout karyogamy, as the MTOCs are crucial to nuclear migration, fusion and polarity. Previous work has shown that the proteins Kar9p, Kar3p and Kar1p (all of which are components of the MTOCs) are required for karyogamy to be completed. Additionally, Kar2p. Kar5p, Kar7p and Kar8p, which are all part of the nuclear envelope, are required for nuclear membrane envelope fusion after the two SPBs have come into close apposition. Electron microscopy, and specifically electron tomography of semi-thick sections, has proven to be invaluable for studying MTOC-related processes, because it permits the reconstruction of entire microtubule arrays from MTOCs within a single cell. As such, the application of electron tomography to the process of karyogamy should provide insights into previously unknown processes concerning the involvement MTOCs in this system.