Burbank Kendra S, Groen Aaron C, Perlman Zachary E, Fisher Daniel S, Mitchison Timothy J
Department of Physics, Harvard University, Cambridge, MA 03138, USA.
J Cell Biol. 2006 Nov 6;175(3):369-75. doi: 10.1083/jcb.200511112.
Anastral meiotic spindles are thought to be organized differently from astral mitotic spindles, but the field lacks the basic structural information required to describe and model them, including the location of microtubule-nucleating sites and minus ends. We measured the distributions of oriented microtubules in metaphase anastral spindles in Xenopus laevis extracts by fluorescence speckle microscopy and cross-correlation analysis. We localized plus ends by tubulin incorporation and combined this with the orientation data to infer the localization of minus ends. We found that minus ends are localized throughout the spindle, sparsely at the equator and at higher concentrations near the poles. Based on these data, we propose a model for maintenance of the metaphase steady-state that depends on continuous nucleation of microtubules near chromatin, followed by sorting and outward transport of stabilized minus ends, and, eventually, their loss near poles.
无星减数分裂纺锤体被认为与有星有丝分裂纺锤体的组织方式不同,但该领域缺乏描述和模拟它们所需的基本结构信息,包括微管成核位点和负端的位置。我们通过荧光斑点显微镜和互相关分析测量了非洲爪蟾提取物中期无星纺锤体中定向微管的分布。我们通过微管蛋白掺入定位正端,并将其与方向数据结合以推断负端的定位。我们发现负端遍布纺锤体,在赤道处稀疏分布,在两极附近浓度较高。基于这些数据,我们提出了一个中期稳态维持模型,该模型依赖于染色质附近微管的持续成核,随后是稳定负端的分选和向外运输,最终它们在两极附近丢失。