Physiology of Chromosome Movement in Lysed Cell Models

Abstract

It has long been recognized that anaphase consists of two distinct motile events: movement of chromosomes to the poles, and the separation of the poles (spindle elongation). In the mammalian spindle, e.g. PtK₁ cells, the chromosomes move at one speed until they reach a separation about equal in length to the original metaphase spindle, then they slow down (Brinkley and Cartwright 1971; Cande 1978). Chromosomes and poles then move together until the spindle is about twice its original length. Structural studies of the arrangement and redistribution of microtubules at anaphase suggest that each motile event may be associated with a particular class of microtubules (Fuge 1977; McIntosh et al. 1975; McDonald et al. 1977; Inoué and Ritter 1978). The chromosome movement to the poles is associated with kinetochore microtubules and spindle elongation with nonkinetochore microtubules, especially the central spindle.