洋葱小孢子母细胞减数分裂过程中微管分布变化

Microtubule Distribution and Change during Meiosis of Microspore Mother Cells of Allium cepa L.

应用间接免疫荧光标记技术和激光共聚焦扫描显微镜成像技术观察洋葱小孢子母细胞减数分裂过程中微管分布变化。减数分裂之前,小孢子母细胞中的微管较短,呈辐射状,由细胞核表面向四周扩散。减数分裂开始后,细胞质中的一部分微管蛋白聚集成纺锤体微管,控制染色体的分布。进入减数分裂I后期,纺锤体微管变为牵引染色体移向两极的着丝粒微管和连接纺锤体两极的极丝微管。之后,所有微管集中在两个核之间,构成成膜体。然后,微管解聚成微管蛋白弥散在细胞质中。减数分裂I完成后,二分体2个子细胞中的微管蛋白又聚集成2个纺锤体微管,开始减数分裂II过程。经过减数分裂II中期,2个二分体细胞中的微管再次集中在2个细胞核之间形成成膜体,隔离2个细胞核。此后,微管蛋白解聚,弥散分布在小孢子细胞质中。

Microtubules change during microsporogenesis of Allium cepa was studied using immunofluorescence and confocal laser scanning photomicrographic techniques.Before meiosis of microspore mother cells,the microtubules in the cell cytoplasm were short and spread from nucleus to periplasm.At the beginning of meiosis,the microtubulin in the cells concentrated to form spindle microtubules for regular chromosome position.After metaphase I,some spindle microtubules became centromeric microtubules which shorted to pull chromosomes toward two polarities and some polar microtubules which connected two polarities.In telophase I,centromeric and polar microtubules disappeared completely,and some new microtubules accumulated between two nuclei to form phragmoplast.Then,phragmoplast microtubules depolymerized as microtubulin to disperse in the cytoplasm of two dyad cells.At the beginning of meiosis II,the tubulin in two dyad cells accumulated again to form spindle microtubules to regulate chromosome movement.In the telophase of meiosis II,microtubules accumulated again between two dyad nuclei to form phragmoplast for two nuclei separation.Then,the microtubules depolymerized to become microtubulin and dispersed in cytoplasm of tetrad microspores.