McDonald K L, O'Toole E T, Mastronarde D N, McIntosh J R
Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder 80309-0347.
J Cell Biol. 1992 Jul;118(2):369-83. doi: 10.1083/jcb.118.2.369.
We have analyzed the fine structure of 10 chromosomal fibers from mitotic spindles of PtK1 cells in metaphase and anaphase, using electron microscopy of serial thin sections and computer image processing to follow the trajectories of the component microtubules (MTs) in three dimensions. Most of the kinetochore MTs ran from their kinetochore to the vicinity of the pole, retaining a clustered arrangement over their entire length. This MT bundle was invaded by large numbers of other MTs that were not associated with kinetochores. The invading MTs frequently came close to the kinetochore MTs, but a two-dimensional analysis of neighbor density failed to identify any characteristic spacing between the two MT classes. Unlike the results from neighbor density analyses of interzone MTs, the distributions of spacings between kinetochore MTs and other spindle MTs revealed no evidence for strong MT-MT interactions. A three-dimensional analysis of distances of closest approach between kinetochore MTs and other spindle MTs has, however, shown that the most common distances of closest approach were 30-50 nm, suggesting a weak interaction between kinetochore MTs and their neighbors. The data support the ideas that kinetochore MTs form a mechanical connection between the kinetochore and the pericentriolar material that defines the pole, but that the mechanical interactions between kinetochore MTs and other spindle MTs are weak.
我们利用连续超薄切片电子显微镜技术和计算机图像处理技术，在三维空间中追踪组成微管（MTs）的轨迹，分析了中期和后期PtK1细胞有丝分裂纺锤体中10条染色体纤维的精细结构。大多数动粒微管从其动粒延伸至极体附近，在其整个长度上保持成束排列。这个微管束被大量与动粒无关的其他微管侵入。侵入的微管经常靠近动粒微管，但对相邻密度的二维分析未能确定这两类微管之间的任何特征间距。与中间区微管的相邻密度分析结果不同，动粒微管与其他纺锤体微管之间间距的分布没有显示出强烈的微管-微管相互作用的证据。然而，对动粒微管与其他纺锤体微管之间最近接近距离的三维分析表明，最常见的最近接近距离为30-50纳米，这表明动粒微管与其相邻微管之间存在弱相互作用。这些数据支持以下观点：动粒微管在动粒和定义极体的中心粒周围物质之间形成机械连接，但动粒微管与其他纺锤体微管之间的机械相互作用较弱。
