車軸藻脱膜モデルによる原形質流動の研究

抄録

Two types of demembranated cell models have been established using Characeae internodal cells; the tonoplast-free cell model and the plasmalemma-permeabilized cell model. In these models, both ATP and Mg²⁺ were essential for the maintenance of cytoplasmic streaming. Ca²⁺ inhibited the streaming in both models. However, the Ca²⁺-sensitivity of the streaming in the plasmalemma-permeabilized model was 1000 times higher than the tonoplast-free model, suggesting that some Ca²⁺-sensitizing component was dispersed or disorganized by the disintegration of the tonoplast. Using the actin bundles present in the tonoplast-free cells, the streaming was reconstituted with the endoplasm from other Characeae cells or the rabbit skeletal muscle, scallop or Physarum myosin. Ca²⁺ accelearated the streaming reconstituted with scallop myosin but inhibited that reconstituted with Physarum myosin. These opposite effects of Ca²⁺ on reconstituted streamings agree with the effects of Ca²⁺ on the respective actomyosin ATPases.