O'Toole E T, Mastronarde D N, Giddings T H, Winey M, Burke D J, McIntosh J R
Boulder Laboratory for 3-D Fine Structure, Department of Molecular, Cellular, and Developmental Biology, University of Colorado 80309-0347, USA.
Mol Biol Cell. 1997 Jan;8(1):1-11. doi: 10.1091/mbc.8.1.1.
The three-dimensional organization of mitotic microtubules in a mutant strain of Saccharomyces cerevisiae has been studied by computer-assisted serial reconstruction. At the nonpermissive temperature, cdc20 cells arrested with a spindle length of approximately 2.5 microns. These spindles contained a mean of 81 microtubules (range, 56-100) compared with 23 in wild-type spindles of comparable length. This increase in spindle microtubule number resulted in a total polymer length up to four times that of wild-type spindles. The spindle pole bodies in the cdc20 cells were approximately 2.3 times the size of wild-type, thereby accommodating the abnormally large number of spindle microtubules. The cdc20 spindles contained a large number of interpolar microtubules organized in a "core bundle." A neighbor density analysis of this bundle at the spindle midzone showed a preferred spacing of approximately 35 nm center-to-center between microtubules of opposite polarity. Although this is evidence of specific interaction between antiparallel microtubules, mutant spindles were less ordered than the spindle of wild-type cells. The number of noncore microtubules was significantly higher than that reported for wild-type, and these microtubules did not display a characteristic metaphase configuration. cdc20 spindles showed significantly more cross-bridges between spindle microtubules than were seen in the wild type. The cross-bridge density was highest between antiparallel microtubules. These data suggest that spindle microtubules are stabilized in cdc20 cells and that the CDC20 gene product may be involved in cell cycle processes that promote spindle microtubule disassembly.
通过计算机辅助的连续重建技术，对酿酒酵母突变株有丝分裂微管的三维结构进行了研究。在非允许温度下，cdc20细胞停滞时纺锤体长度约为2.5微米。这些纺锤体平均含有81根微管（范围为56 - 100根），而长度相当的野生型纺锤体含有23根微管。纺锤体微管数量的增加导致聚合物总长度达到野生型纺锤体的四倍。cdc20细胞中的纺锤极体大小约为野生型的2.3倍，从而能够容纳数量异常多的纺锤体微管。cdc20纺锤体含有大量以“核心束”形式组织的极间微管。在纺锤体中区对该束进行邻域密度分析显示，相反极性的微管之间中心距约为35纳米，存在优先间距。虽然这证明了反平行微管之间存在特定相互作用，但突变纺锤体的有序程度低于野生型细胞的纺锤体。非核心微管的数量显著高于野生型报道的数量，并且这些微管未呈现典型的中期构型。cdc20纺锤体中纺锤体微管之间的交叉桥明显多于野生型。反平行微管之间的交叉桥密度最高。这些数据表明，cdc20细胞中的纺锤体微管是稳定的，并且CDC20基因产物可能参与促进纺锤体微管解聚的细胞周期过程。
