Bajer A S
J Cell Biol. 1982 Apr;93(1):33-48. doi: 10.1083/jcb.93.1.33.
The oscillations of chromosomes associated with a single spindle pole in monocentric and bipolar spindles were analysed by time-lapse cinematography in mitosis of primary cultures of lung epithelium from the newt Taricha granulosa. Chromosomes oscillate toward and away from the pole in all stages of mitosis including anaphase. The duration, velocity, and amplitude of such oscillations are the same in all stages of mitosis. The movement away from the pole in monocentric spindle is rapid enough to suggest the existence of a previously unrecognized active component in chromosome movement, presumably resulting from a pushing action of the kinetochore fiber. During prometaphase oscillations, chromosomes may approach the pole even more closely than at the end of anaphase. Together, these observations demonstrate that a monopolar spindle is sufficient to generate the forces for chromosome transport, both toward and away from the pole. The coordination of the aster/centrosome migration in prophase with the development of the kinetochore fibers determines the course of mitosis. After the breaking of the nuclear envelope in normal mitosis, aster/centrosome separation is normally followed by the rapid formation of bipolar chromosomal fibers. There are two aberrant extremes that may result from a failure in coordination between these processes: (a) A monocentric spindle will arise when aster separation does not occur, and (b) an anaphaselike prometaphase will result if the aster/centrosomal complexes are already well-separated and bipolar chromosomal fibers do not form. In the latter case, the two monopolar prometaphase half-spindles migrate apart, each containing a random number of two chromatid (metaphase) monopolar-oriented chromosomes. This random segregation of prometaphase chromosome displays many features of a standard anaphase and may be followed by a false cleavage. The process of polar separation during prometaphase occurs without any visible interzonal structures. Aster/centrosomes and monopolar spindles migrate autonomously by an unknown mechanism. There are, however, firm but transitory connections between the aster center and the kinetochores as demonstrated by the occasional synchrony of centrosome-kinetochore movement. The data suggest that aster motility is important in the progress of both prometaphase and anaphase in normal mitosis.
通过延时摄影技术，对粗皮渍螈肺上皮原代培养细胞有丝分裂过程中，与单极纺锤体相关的染色体振荡进行了分析。在有丝分裂的所有阶段，包括后期，染色体都朝着纺锤极来回振荡。这种振荡的持续时间、速度和幅度在有丝分裂的所有阶段都是相同的。在单极纺锤体中，染色体远离纺锤极的移动速度足够快，这表明在染色体移动过程中存在一种先前未被认识的活跃成分，推测是由动粒纤维的推动作用导致的。在前中期振荡过程中，染色体可能比后期结束时更接近纺锤极。这些观察结果共同表明，单极纺锤体足以产生促使染色体向纺锤极移动以及远离纺锤极移动的力量。前期星体/中心体迁移与动粒纤维的发育之间的协调决定了有丝分裂的进程。在正常有丝分裂中，核膜破裂后，星体/中心体分离通常紧接着双极染色体纤维的快速形成。这些过程之间的协调失败可能导致两种异常极端情况：（a）如果星体不分离，就会形成单极纺锤体；（b）如果星体/中心体复合物已经充分分离而双极染色体纤维没有形成，就会导致类似后期的前中期。在后一种情况下，两个单极前中期半纺锤体彼此分开移动，每个半纺锤体包含随机数量的两条染色单体（中期）单极取向染色体。前中期染色体的这种随机分离表现出许多标准后期的特征，可能随后会出现假分裂。前中期两极分离过程中没有任何可见的中间区域结构。星体/中心体和单极纺锤体通过未知机制自主迁移。然而，正如中心体 - 动粒运动偶尔的同步所表明的，星体中心与动粒之间存在牢固但短暂的连接。数据表明，星体运动在正常有丝分裂的前中期和后期进程中都很重要。
