Hush J, Wu L, John P C, Hepler L H, Hepler P K
School of Biological Sciences, University of Sydney, Australia.
Cell Biol Int. 1996 Apr;20(4):275-87. doi: 10.1006/cbir.1996.0031.
The regulation of mitosis in higher plant cells has been investigated by microinjecting protein kinase from the metaphase-arresting (met1) mutant of Chlamydomonas. Biochemical characterization of this enzyme complex confirms the presence of a p34cdc2/cyclin B-like kinase. The enzyme was injected into living stamen hair cells of Tradescantia virginiana in which microtubules (MTs) were visualized using fluorescent analogue cytochemistry and confocal laser scanning microscopy. Microinjection of this p34cdc2/cyclin B-like kinase caused rapid disassembly of the preprophase band of MTs but not of interphase-cortical, spindle or phragmoplast MTs. Effects of the enzyme on the cytomorphology of live prophase cells were also monitored using video microscopy. We found that injection of this enzyme accelerated chromatin condensation and nuclear envelope breakdown. This indicates the presence and function in plants of an enzyme that can initiate nuclear division similar to the maturation or mitosis promoting factor (MPF) of animal cells. These studies provide the first direct evidence that the mitotically-active form of plant MPF can drive disassembly of preprophase band MTs, chromosome condensation and initiation of mitosis in plant cells.
通过显微注射来自衣藻中期阻滞（met1）突变体的蛋白激酶，对高等植物细胞有丝分裂的调控进行了研究。这种酶复合物的生化特性证实了存在一种p34cdc2/细胞周期蛋白B样激酶。将该酶注射到弗吉尼亚紫露草的活雄蕊毛细胞中，利用荧光类似物细胞化学和共聚焦激光扫描显微镜观察微管（MTs）。显微注射这种p34cdc2/细胞周期蛋白B样激酶导致前期带MTs迅速解体，但不影响间期皮质、纺锤体或成膜体MTs。还使用视频显微镜监测了该酶对活前期细胞细胞形态的影响。我们发现注射这种酶加速了染色质凝聚和核膜破裂。这表明植物中存在一种能启动核分裂的酶，其功能类似于动物细胞的成熟或有丝分裂促进因子（MPF）。这些研究提供了首个直接证据，表明植物MPF的有丝分裂活性形式可驱动植物细胞中前期带MTs的解体、染色体凝聚和有丝分裂的启动。
