Fisher D D, Cyr R J
Department of Biology, Pennsylvania State University, University Park, USA.
Gravit Space Biol Bull. 2000 Jun;13(2):67-73.
Plant cells perceive forces that arise from the environment and from the biophysics of plant growth. These forces provide meaningful cues that can affect the development of the plant. Seedlings of Arabidopsis thaliana were used to examine the cytoplasmic tensile character of cells that have been implicated in the gravitropic response. Laser-trapping technology revealed that the starch-containing statoliths of the central columella cells in root caps are held loosely within the cytoplasm. In contrast, the peripheral cells have starch granules that are relatively resistant to movement. The role of the actin cytoskeleton in affecting the tensile character of these cells is discussed. To explore the role that biophysical forces might play in generating developmental cues, we have developed an experimental model system in which protoplasts, embedded in a synthetic agarose matrix, are subjected to stretching or compression. We have found that protoplasts subjected to these forces from five minutes to two hours will subsequently elongate either at right angles or parallel to the tensive or compressive force vector. Moreover, the cortical microtubules are found to be organized either at right angles or parallel to the tensive or compressive force vector. We discuss these results in terms of an interplay of information between the extracellular matrix and the underlying cytoskeleton.
植物细胞能够感知来自环境以及植物生长生物物理学过程产生的力。这些力提供了有意义的线索，可影响植物的发育。拟南芥幼苗被用于研究与向重力性反应有关的细胞的细胞质拉伸特性。激光捕获技术显示，根冠中柱细胞含淀粉的平衡石松散地存在于细胞质中。相比之下，外围细胞具有相对抗移动的淀粉颗粒。文中讨论了肌动蛋白细胞骨架在影响这些细胞拉伸特性方面的作用。为了探究生物物理力在产生发育线索中可能发挥的作用，我们开发了一个实验模型系统，其中嵌入合成琼脂糖基质中的原生质体受到拉伸或压缩。我们发现，在五分钟到两小时内受到这些力作用的原生质体随后会以直角或平行于拉伸或压缩力向量的方向伸长。此外，发现皮层微管要么以直角要么平行于拉伸或压缩力向量排列。我们根据细胞外基质与底层细胞骨架之间信息的相互作用来讨论这些结果。
