Dynamics of cytoskeleton myosin during the differentiation of xylem cells in trees

树木木质部细胞分化过程中细胞骨架肌球蛋白的动态

基本信息

批准号：
14560127
负责人：
FUNADA Ryo
金额：
$ 2.3万
依托单位：
Tokyo University of Agriculture and Technology (2003)Hokkaido University (2002)
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2003
项目状态：
已结题

项目摘要

Cambial cells in tress differentiate into secondary xylem cells through a process of cell expansion, cell wall thickenings, lignification and cell death. During the differentiation, xylem, cells develop modifications of the cell wall such as pits and helical thickenings by the localized deposition of cell wall materials. Our previous results indicated that the localization of cell wall formation was related to the localized appearance and disappearance of components of the cytoskeleton, namely cortical microtubules and actin filaments, indicating that components of the cytoskeleton control the localized deposition of cell wall materials. However, we have only a few papers showing how the localization of components of the cytoskeleton is controlled. We analyzed here the role of myosins, so called motor-proteins, in the differentiation of xylem cells in tress because myosins utilize ATP to generate mechanical force along actin filaments. Firstly, we established the method of visualization of myosin in xylem cells. Myosins were immuno-stained with a monoclonal antibody against myosins and then FITC-conjugated secondary antibody. They were observed by confocal laser scanning microscopy. Fluorescence derived from myosins was observed in differentiating xylem cells. Myosins were aggregated at the sites of apertures of intertracheal bordered pits. As xylem cells differentiated, the aggregation of myosins decreased in diameter. The reduction in diameter of myosins was associated with the development of bordered pits. Such a localization of myosins was a similar to that of actin filaments in differentiating xylem cells. Our results indicate that an acto-myosin contractile system, being a similar manner to the contraction of mammalian muscle, might be present at the site of pit formation. We conclude that myosins play an important role in the formation of modified structure, therefore controlling the morphogenesis of secondary xylem cells.

发束中的形成层细胞通过细胞扩张、细胞壁增厚、木质化和细胞死亡的过程分化为次生木质部细胞。在分化过程中，木质部细胞通过细胞壁材料的局部沉积而形成细胞壁的修饰，例如凹坑和螺旋增厚。我们前期的研究结果表明，细胞壁形成的定位与细胞骨架成分（即皮质微管和肌动蛋白丝）的局部出现和消失有关，表明细胞骨架成分控制细胞壁材料的局部沉积。然而，我们只有几篇论文展示了如何控制细胞骨架成分的定位。我们在此分析了肌球蛋白（所谓的运动蛋白）在发束木质部细胞分化中的作用，因为肌球蛋白利用 ATP 沿着肌动蛋白丝产生机械力。首先，我们建立了木质部细胞中肌球蛋白的可视化方法。使用针对肌球蛋白的单克隆抗体对肌球蛋白进行免疫染色，然后使用 FITC 偶联的二抗进行免疫染色。通过共焦激光扫描显微镜观察它们。在分化的木质部细胞中观察到源自肌球蛋白的荧光。肌球蛋白聚集在气管间缘凹坑的孔处。随着木质部细胞分化，肌球蛋白聚集的直径减小。肌球蛋白直径的减小与有缘凹坑的形成有关。肌球蛋白的这种定位类似于分化木质部细胞中肌动蛋白丝的定位。我们的结果表明，肌动球蛋白收缩系统与哺乳动物肌肉的收缩方式相似，可能存在于小凹形成的部位。我们得出结论，肌球蛋白在修饰结构的形成中发挥重要作用，因此控制次生木质部细胞的形态发生。