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首页> 外文期刊>Protoplasma: An International Journal of Cell Biology >STRUCTURAL BASIS FOR THE RED LIGHT INDUCED REPOLARIZATION OF TIP GROWTH IN CAULONEMA CELLS OF CERATODON PURPUREUS
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STRUCTURAL BASIS FOR THE RED LIGHT INDUCED REPOLARIZATION OF TIP GROWTH IN CAULONEMA CELLS OF CERATODON PURPUREUS

机译：红光诱导斑节菜caulonema细胞中Tip生长再分化的结构基础

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Two dynamic changes are associated with the phytochrome-regulated phototropic response in tip cells of the moss Ceratodon purpureus: a tip-located gradient shift of chlortetracycline (CTC)-stained calcium and a structural reorganization of apical microfilaments (MFs). We examined the interdependence of these processes. Cells were treated with the antimicrotubule drug oryzalin, the antimicrofilament drug cytochalasin-D, and the calcium channel blocker nifedipine, respectively. The effects on phototropic growth, on the structural alignment of the cytoskeleton (microtubules, MTs; microfilaments) and on the distribution of CTC-stained calcium were studied under each of these conditions. In gravitropically growing tip cells the apical MFs form a cortical collar-like structure, consisting of actin bundles with a parallel axial alignment. These MFs point towards the presumptive growing point, a weakly stained region in the tip of the cell from which bundles are absent. MTs are present in the cortex and in the endoplasm of the tip, predominantly oriented longitudinally. The MTs converge within the central apex. The cells show a steep tip-to-base CTC-calcium gradient with its highest signal in the central apex. Destruction of MTs by 1 mu M oryzalin induces several translocational effects: (i) the growing zone and phototropic outgrowth shift from the apex to subapical parts of the cell; (ii) the structural integrity of the apical MFs and the tip-to-base alignment of the CTC-calcium gradient are disturbed; and (iii) the red light induced gradient shift and the reorientation of MFs proceed in an expanded area spanning from the tip to subapical parts of the cell. Cytochalasin-D (10 mu g/ml) destroys the MFs. Under these conditions tip growth stops and the phototropic outgrowth is suppressed. The apical MT-structure and the CTC-calcium gradient are not influenced by the agent. Unilateral red light still induces the light-directed translocation of the gradient. Tip cells ''memorize'' a unilateral irradiation applied during growth inhibition with cytochalasin-D. After recovery in darkness the cells start to grow in the former light direction. The restoration of the MFs precedes the outgrowth. The structural alignment of the rebuilt actin bundles indicates the future growth direction. The calcium channel blocker nifedipine (10 mu M) also inhibits tip growth and concurrently phototropic outgrowth. Nifedipine destroys the CTC-calcium gradient and apical MFs; MTs are not influenced by the channel blocker. [References: 21]
机译：两个动态变化与苔藓紫癜的尖端细胞中的植物色素调节的光致反应有关：绿霉素（CTC）染色的钙的尖端定位梯度位移和根尖微丝（MF）的结构重组。我们研究了这些过程的相互依赖性。细胞分别用抗微管药物oryzalin，抗微丝药物cytochalasin-D和钙通道阻滞剂硝苯地平处理。在这些条件下，分别研究了对光致生长，对细胞骨架（微管，MT，微丝）的结构排列以及对CTC染色的钙的分布的影响。在重力生长的尖端细胞中，顶端MF形成皮质领状结构，由具有平行轴向排列的肌动蛋白束组成。这些MF指向推测的生长点，即细胞尖端缺乏染色的薄弱区域。 MT存在于尖端的皮质和内质中，主要是纵向取向的。 MT会聚在中央顶点内。细胞显示出陡峭的从尖端到基础的四氯化碳钙梯度，其最高信号位于中央顶点。 1μM的米杂列素对MT的破坏会引起几种易位效应：（i）生长区和光致生长产物从细胞的顶端转移到根尖以下; （ii）顶端MF的结构完整性和CTC-钙梯度的从尖端到碱基的排列受到干扰; （iii）红光引起的梯度移动和MF的重新定向在从细胞的尖端到根尖的整个扩展区域内进行。细胞松弛素-D（10μg / ml）破坏了MF。在这些条件下，尖端生长停止并且光致增生被抑制。根尖MT结构和CTC钙梯度不受该试剂的影响。单边红光仍会引起渐变的光定向移位。尖端细胞“记忆”在用细胞松弛素-D抑制生长的过程中施加的单侧辐射。在黑暗中恢复后，细胞开始沿先前的光方向生长。 MF的恢复先于增长。重建的肌动蛋白束的结构排列指示了未来的增长方向。钙通道阻滞剂硝苯地平（10μM）也抑制针尖生长，并同时抑制光致生长。硝苯地平破坏了四氯化碳钙梯度和心尖MF。 MT不受通道阻止程序的影响。 [参考：21]

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