The role of microtubules in vessel member differentiation inColeus
The role of microtubules in vessel member differentiation inColeus
复制标题
微管在锦紫苏血管成员分化中的作用
DOI：
10.1007/bf01279052
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发表时间：
1971
期刊：
影响因子：
2.9
通讯作者：
D. Fosket
中科院分区：
文献类型：
--
作者：
P. K. Hepler;D. Fosket
通过使用抗微管药物秋水仙碱，研究了微管在彩叶草茎段培养中导管分子形成中的作用。秋水仙素处理的培养茎段产生的木质部分化的双重影响。如果在茎段分离时或之后不久施用，伤口血管构件形成几乎完全阻断。然而，如果在培养的第三天后施用秋水仙素，它不会抑制分化，而是形成大量具有高度变形的次生壁的木质部元件。这两种效应都与秋水仙素对微管的特异性亲和力有关。在第一种情况下，它表明，秋水仙素块有丝分裂，大概是通过破坏纺锤体，从而抑制分裂的先决条件是木质部分化的启动。而如果在必要的准备性分裂发生后施用秋水仙碱，它会特异性地破坏与次生壁发育带有关的皮层微管，从而导致异常的壁沉积。药物的光和电子显微镜分析-处理过的细胞显示次生壁在初生壁表面上变得模糊，并且不保留次生增厚的离散带状图案特征在未经处理的细胞中。秋水仙素处理的次生壁在KMnO 4固定材料的检查表明，在没有微管的纤维素微纤维失去其正常的平行方向，并沉积在漩涡和弯曲的配置，并往往位于锐角的轴的次生壁带。微管，因此，似乎发挥了重要作用，在定义的模式次生壁沉积和定向的纤维素微纤维的壁。除了微管的因素也在控制次生壁的图案，因为我们观察到，即使在没有微管的次生加厚的两个相邻的木质部元件直接沉积在共同的初生壁彼此相对。
SummaryThe role of microtubules in tracheary element formation in cultured stem segments ofColeus has been investigated through the use of the antimicrotubule drug, colchicine. Colchicine treatment of the cultured stem segments produced a dual effect on xylem differentiation. If applied at the time of stem segment isolation or shortly thereafter, wound vessel member formation is almost completely blocked. However, if colchicine is applied after the third day of culture, it does not inhibit differentiation, but instead large numbers of xylem elements are formed which have highly deformed secondary walls. Both effects are related to colchicine's specific affinity for microtubules. In the first case it is shown that colchicine blocks mitosis, presumably by destroying the spindle apparatus, and thus inhibits divisions which are prerequisite for the initiation of xylem differentiation. While, if colchicine is applied after the necessary preparative divisions have taken place, it destroys specifically the cortical microtubules associated with the developing bands of secondary wall, thus causing aberrant wall deposition.Light and electron microscopic analysis of drug-treated cells reveals that the secondary wall becomes smeared over the surface of the primary wall and does not retain the discrete banded pattern characteristic of secondary thickenings in untreated cells. Examination of colchicine-treated secondary walls in KMnO4 fixed material shows that in the absence of microtubules the cellulose microfibrils lose their normal parallel orientation and are deposited in swirls and curved configurations, and often lie at sharp angles to the axis of the secondary wall band. Microtubules, thus, appear to play a major role in defining the pattern of secondary wall deposition and in directing the orientation of the cellulose microfibrils of the wall. Factors in addition to microtubules also act in controlling the secondary wall pattern, since we observe that even in the absence of microtubules secondary thickenings of two adjacent xylem elements are deposited directly opposite one another across the common primary wall.