Cortical microtubules are considered to regulate the direction of cellulose microfibril deposition. Despite their significant role in determining cell morphology, cortical microtubules completely disappear from the cell cortex during M phase and become reorganized at G1 phase. The mechanism by which these microtubules become properly formed again is, however, still unclear. We have proposed that the origin of cortical microtubules is on the daughter nuclear surface, but further cortical microtubule reorganization occurs at the cell cortex. Hence it is probable that the locations of microtubule organizing centers (MTOCs) are actively changing. However, the actual MTOC sites of cortical microtubules were not clearly determined. In this paper, we have examined the distribution of gamma-tubulin, one of the key molecules of MTOCs in various organisms, during cortical microtubule reorganization using both immunofluorescence and a GFP reporter system. Using a monoclonal antibody (clone G9) that recognizes highly conserved residues in y-tubulin, y-tubulin was found to be constitutively expressed and to be clearly localized to microtubule structures, such as the preprophase bands, spindles, and phragmoplasts, specific to each cell cycle stage. This distribution pattern was confirmed by the GFP reporter system. During cortical microtubule reorganization at the M to G1 transition phase, gamma-tubulin first accumulated at the daughter nuclear surfaces, and then seemed to spread onto the cell cortex along with microtubules elongating from the daughter nuclei. Based on the results, it was confirmed that daughter nuclear surfaces acted as origins of cortical microtubules, and that further reorganization occurred on the cell cortex.

中文翻译：

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烟草 BY-2 细胞 M/G1 界面皮质微管重组过程中 γ-微管蛋白的分布。


皮质微管被认为调节纤维素微纤维沉积的方向。尽管皮层微管在决定细胞形态方面发挥着重要作用，但它们在 M 期从细胞皮层完全消失，并在 G1 期重组。然而，这些微管再次正确形成的机制仍不清楚。我们提出皮质微管的起源位于子核表面，但进一步的皮质微管重组发生在细胞皮质。因此，微管组织中心（MTOC）的位置可能正在积极变化。然而，皮质微管的实际 MTOC 位点尚未明确确定。在本文中，我们使用免疫荧光和 GFP 报告系统检查了皮质微管重组过程中 MTOC 的关键分子之一 γ-微管蛋白的分布。使用识别 y-微管蛋白中高度保守残基的单克隆抗体（克隆 G9），发现 y-微管蛋白是组成型表达的，并且清楚地定位于微管结构，例如前期带、纺锤体和成膜体，对每个微管结构具有特异性。细胞周期阶段。 GFP 报告系统证实了这种分布模式。在 M 到 G1 过渡期的皮层微管重组过程中，γ-微管蛋白首先在子核表面积累，然后似乎与从子核延伸的微管一起扩散到细胞皮层上。基于这些结果，证实了子核表面是皮质微管的起源，并且细胞皮质上发生了进一步的重组。