Nakagaki T, Yamada H, Ueda T
Bio-mimetic Control Research Center, The Institute of Physical and Chemical Research (RIKEN), Moriyama, Nagoya, Japan.
Biophys Chem. 2000 May 15;84(3):195-204. doi: 10.1016/s0301-4622(00)00108-3.
The relationship between cell shape and rhythmic contractile activity in the large amoeboid organism Physarum polycephalum was studied. The organism develops intricate networks of veins in which protoplasmic sol moved to and fro very regularly. When migrating on plain agar, the plasmodium extends like a sheet and develops dendritic veins toward the rear. After a particular stimulation, the vein organization changes into veinless or vein-network structures. In both structures, the mixing rate of the protoplasm, which is related to communication among contraction oscillators, decreased compared with that of the dendritic one. Accompanying these changes in vein structure, the spatio-temporal pattern of the rhythmic contraction changed into a small-structured pattern from a synchronized one. In the above process, cell shape affects the contraction pattern, but, conversely, the contraction pattern effects the cell shape. To demonstrate this, a phase difference in the rhythmic contraction was induced artificially by entraining the intrinsic rhythm to external temperature oscillations. New veins then formed along the direction parallel to the phase difference of the rhythm. Consequently, the vein organization of the cell interacts with the contractile activity to form a feedback loop in a mechanism of contraction pattern formation.
对大型变形虫状生物多头绒泡菌中细胞形状与节律性收缩活动之间的关系进行了研究。该生物会形成复杂的静脉网络，原生质溶胶在其中非常有规律地来回移动。当在普通琼脂上迁移时，疟原虫会像薄片一样伸展，并向后方发育出树枝状静脉。经过特定刺激后，静脉组织会转变为无静脉或静脉网络结构。在这两种结构中，与收缩振荡器之间的通讯相关的原生质混合速率，与树枝状结构相比有所降低。伴随着静脉结构的这些变化，节律性收缩的时空模式从同步模式转变为小结构模式。在上述过程中，细胞形状影响收缩模式，但相反，收缩模式也影响细胞形状。为了证明这一点，通过使内在节律与外部温度振荡同步，人为诱导了节律性收缩中的相位差。然后沿着与节律相位差平行的方向形成了新的静脉。因此，细胞的静脉组织与收缩活动相互作用，在收缩模式形成机制中形成一个反馈回路。
