Chromosome behavior after laser microirradiation of a single kinetochore in mitotic PtK2 cells.
Chromosome behavior after laser microirradiation of a single kinetochore in mitotic PtK2 cells.
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DOI：
10.1083/jcb.88.3.543
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发表时间：
1981-03
期刊：
影响因子：
--
通讯作者：
Berns MW
中科院分区：
文献类型：
--
作者：
McNeill PA;Berns MW
用532 nm激光照射有丝分裂的PtK 2细胞，研究了着丝粒在染色体运动中的作用。当单个染色单体的动粒在有丝分裂的前中期或中期被照射时，整个染色体向未被照射的动粒所指向的极移动，而剩余的染色体聚集在中期板上。被照射的染色体的染色单体保持彼此附着，直到分裂后期，此时它们分开1或2微米的距离，并且保持彼此平行，不经历任何向极分离。电子显微镜观察显示，照射后的染色单体要么没有可识别的动粒结构，要么是典型的失活动粒，其中存在三层结构，但没有微管与之相连。对照射后染色体运动的图形分析显示，染色体以约3微米/分钟的速度迅速向极点移动。如果染色体在照射时靠近一个极点，并且朝向该极的动粒被照射，染色体穿过纺锤体移动到相反的极。当染色体穿过赤道区时，其速度减慢，但两个半纺锤体中的速度与单个染色单体的后期速度大致相同。因此，单个动粒以与单个染色单体相同的速度移动两倍于正常质量的染色质（两个染色单体），这表明动粒移动的速度在一定范围内与其相关的质量无关。
The role of the kinetochore in chromosome movement was studied by 532- nm wavelength laser microirradiation of mitotic PtK2 cells. When the kinetochore of a single chromatid is irradiated at mitotic prometaphase or metaphase, the whole chromosome moves towards the pole to which the unirradiated kinetochore is oriented, while the remaining chromosomes congregate on the metaphase plate. The chromatids of the irradiated chromosome remain attached to one another until anaphase, at which time they separate by a distance of 1 or 2 micrometers and remain parallel to each other, not undergoing any poleward separation. Electron microscopy shows that irradiated chromatids exhibit either no recognizable kinetochore structure or a typical inactive kinetochore in which the tri-layer structure is present but has no microtubules associated with it. Graphical analysis of the movement of the irradiated chromosome shows that the chromosome moves to the pole rapidly with a velocity of approximately 3 micrometers/min. If the chromosome is close to one pole at irradiation, and the kinetochore oriented towards that pole is irradiated, the chromosome moves across the spindle to the opposite pole. The chromosome is slowed down as it traverses the equatorial region, but the velocity in both half-spindles is approximately the same as the anaphase velocity of a single chromatid. Thus a single kinetochore moves twice the normal mass of chromatin (two chromatids) at the same velocity with which it moves a single chromatid, showing that the velocity with which a kinetochore moves is independent, within limits, of the mass associated with it.