Self-Organized Electric Structure in Uni- and Multicellular Biological Systems

The electric spatial pattern is often observed in biological systems. The freshwater alga Chara, composed of giant internodal cells, develops alternating periodic bands of acidic and alkaline regions along the cell wall under illumination. Figure 1 shows the formation of 5 alkaline bands along the cell with 70 mm length. The electric potential near the cell surface and the membrane potential also show a similar pattern, which implies an electric current flowing from the acidic to alkaline zone [1–6]. Since the acidic regions elongate, the formation of pattern is directly related to the growth. The band surrounding the circumferential direction of the cell is formed through a gathering process of many small patches at the cell surface [4]. Electric oscillations sometimes appearing under weak light intensity are coherent in the acidic region [3]. This electrochemical spatial pattern is fairly stable in grown cells, but is unstable in very young cells. Even if one of the bands formed on the cell is diminished by some electro-mechanical perturbations, other bands are scarcely changed [7]; the pattern seems a kind of frozen pattern, which has not been investigated yet in detail, although propagative or oscillatory waves of chemical concentrations have been studied well.