Guacci V, Hogan E, Koshland D
Department of Embryology, Carnegie Institution of Washington, Baltimore, Maryland 21210, USA.
Mol Biol Cell. 1997 Jun;8(6):957-72. doi: 10.1091/mbc.8.6.957.
Although general features of chromosome movement during the cell cycle are conserved among all eukaryotic cells, particular aspects vary between organisms. Understanding the basis for these variations should provide significant insight into the mechanism of chromosome movement. In this context, establishing the types of chromosome movement in the budding yeast Saccharomyces cerevisiae is important since the complexes that mediate chromosome movement (microtubule organizing centers, spindles, and kinetochores) appear much simpler in this organism than in many other eukaryotic cells. We have used fluorescence in situ hybridization to begin an analysis of chromosome movement in budding yeast. Our results demonstrate that the position of yeast centromeres changes as a function of the cell cycle in a manner similar to other eukaryotes. Centromeres are skewed to the side of the nucleus containing the spindle pole in G1; away from the poles in mid-M and clustered near the poles in anaphase and telophase. The change in position of the centromeres relative to the spindle poles supports the existence of anaphase A in budding yeast. In addition, an anaphase A-like activity independent of anaphase B was demonstrated by following the change in centromere position in telophase-arrested cells upon depolymerization and subsequent repolymerization of microtubules. The roles of anaphase A activity and G1 centromere positioning in the segregation of budding yeast chromosomes are discussed. The fluorescence in situ hybridization methodology and experimental strategies described in this study provide powerful new tools to analyze mutants defective in specific kinesin-like molecules, spindle components, and centromere factors, thereby elucidating the mechanism of chromosome movement.
尽管在所有真核细胞中，细胞周期内染色体运动的一般特征都是保守的，但不同生物体之间的某些特定方面存在差异。了解这些差异的基础应该能为染色体运动机制提供重要的见解。在这种背景下，确定芽殖酵母酿酒酵母中的染色体运动类型很重要，因为介导染色体运动的复合物（微管组织中心、纺锤体和动粒）在这种生物体中似乎比在许多其他真核细胞中要简单得多。我们已经使用荧光原位杂交技术开始分析芽殖酵母中的染色体运动。我们的结果表明，酵母着丝粒的位置随细胞周期而变化，其方式与其他真核生物相似。在G1期，着丝粒偏向含有纺锤极的细胞核一侧；在中期远离纺锤极，在后期和末期聚集在纺锤极附近。着丝粒相对于纺锤极位置的变化支持了芽殖酵母中存在后期A。此外，通过跟踪微管解聚和随后重新聚合后处于末期停滞的细胞中着丝粒位置的变化，证明了一种独立于后期B的后期A样活性。讨论了后期A活性和G1期着丝粒定位在芽殖酵母染色体分离中的作用。本研究中描述的荧光原位杂交方法和实验策略提供了强大的新工具，可用于分析在特定类驱动蛋白分子、纺锤体成分和着丝粒因子方面存在缺陷的突变体，从而阐明染色体运动的机制。
