Cande W Z, McDonald K L
Nature. 1985;316(6024):168-70. doi: 10.1038/316168a0.
A key step for analysing the mechanochemistry of mitosis would be the isolation of a functional spindle capable of anaphase chromosome movement in vitro. Although Mazia and Dan first isolated spindles in 1952, with one or two possible exceptions, isolated spindles are non-functional. An alternative approach has used permeabilized cells to study anaphase chromosome movement, but these preparations are biochemically and morphologically complex, and hence difficult to analyse. We describe here a simple procedure for isolating diatom spindles which are capable of anaphase spindle elongation in vitro. With addition of ATP, the two half-spindles slide completely apart, with concomitant decrease in the zone of overlap. Electron microscopy reveals decreased numbers of microtubules throughout the spindle after ATP addition and confirms the complete absence of structures beyond the spindle poles. These results are inconsistent with theoretical models of mitosis which suggest that spindle poles are pushed apart by microtubule growth, are pulled apart by external forces applied to the poles, or are released from tension generated during spindle formation. The results are consitent with models that postulate mechanical interactions in the zone of microtubule overlap as a factor in spindle elongation.
分析有丝分裂的机械化学过程的关键一步是在体外分离出能够进行后期染色体移动的功能性纺锤体。尽管马齐亚和丹在1952年首次分离出纺锤体，但除了一两个可能的例外情况外，分离出的纺锤体都没有功能。另一种方法是利用通透细胞来研究后期染色体移动，但这些制备物在生化和形态上都很复杂，因此难以分析。我们在此描述一种简单的程序来分离硅藻纺锤体，这些纺锤体在体外能够进行后期纺锤体伸长。加入ATP后，两个半纺锤体完全分开，重叠区域随之减少。电子显微镜显示加入ATP后整个纺锤体中的微管数量减少，并证实纺锤体两极之外完全没有结构。这些结果与有丝分裂的理论模型不一致，这些理论模型认为纺锤体两极是被微管生长推开、被施加在两极的外力拉开，或者是从纺锤体形成过程中产生的张力中释放出来的。这些结果与假设微管重叠区域的机械相互作用是纺锤体伸长因素的模型一致。
