Analysis on the relocation movement of chloroplasts in fern and moss cells

分析了光和机械刺激诱导蕨类和苔藓细胞叶绿体移动的机制，通过改变外界介质中的钙离子浓度和应用钙离子转运抑制剂(La^&lt；3+&gt；，Gd^&lt；3+&gt；)，分析了钙离子在这些反应的信号转导中的作用。在蕨类和苔藓细胞中，外源Ca~(2+)和Gt~(2+)在机械诱导的叶绿体重定位中是必需的，而在光诱导的叶绿体重定位中不是必需的，说明Ca~(2+)和GFP~(2+)在机械和光诱导的信号转导中的作用不同。在转化子中，在荧光显微镜下很容易观察到活细胞中肌动蛋白细丝和微管的胞内构筑。在光位移过程中和之后，微管与叶绿体紧密结合。在光移位运动过程中也观察到肌动蛋白细丝的重组。在叶绿体聚集区周围出现网状肌动蛋白结构。这些结果表明这两种细胞骨架在叶绿体重新定位运动中起着重要的作用。在蕨类细胞中，这些GFP融合结构不起作用。然而，通过改变荧光标记，我们成功地在活的蕨类细胞中显示了肌动蛋白细丝。

Mechanisms of chloroplast relocation movement induced by light and mechanical stimuli were analyzed in fern and moss cells.Contribution of Ca^<2+> in the signal transduction of these responses was analyzed by changing the Ca^<2+> concentration of external media and by application of Ca^<2+> transport inhibitors (La^<3+>, Gd^<3+>). In both fern and moss cells, influx of Ca^<2+> from the external source was found to be essential in mechano-induced chloroplast relocation but not in the light-induced one, showing the different role of Ca^<2+> in the signal transduction of mechano- and light-induced responses.GFP-tubulin and GFP-talin genes were introduced to moss cells and stable transformants were obtained. In the transformants, intracellular architecture of actin filaments and of microtubules in the live cells was easily observed under fluorescence microscope. During and after photorelocation movement, tight association of microtubules to the chloroplasts was noticed. Reorganization of actin filaments was also observed during photorelocation movement. Reticulate actin structure appeared around the place of chloroplast accumulation. These results indicate the significant roles of both cytoskeletons in the chloroplast relocation movement. In fern cells, these GFP-fusion constructs did not work. However, by changing the fluorescent label, we succeeded in the visualization of actin filaments in live fern cells.