Forma, Vol. 5 (No. 2), pp. 135-152, 1990
Original Paper

Entrainment of Electrochemical Spatial Pattern between Unicellular Biological Systems

T. Matsuno, K. Toko, T. Fujiyoshi , K. Yamafuji and K. Ogata

1Department of Electronics, Faculty of Engineering, Kyushu University 36, Fukuoka 812, Japan
2 Department of Electrical Engineering and Computer Science, Faculty of Engineering, Kumamoto University, Kumamoto 860, Japan
3Department Biochemistry, School of Medical Technology, University of Occupational and Environmental Health, Kitakyushu 807, Japan

(Received July 1, 1990; Accepted November 1, 1990)

Keywords: entrainment, spatial pattern, dissipative structure, Chara

Abstract. Abstrset. The giant internodal cell of green alga Chara develops an alternating periodic band pattern of acid and alkaline regions along the cell surface under illumination. It is the spatially nonuniform and frozen electrochemical pattern associated with the spatial change in the electric membrane potential. This state is a dissipative structure appearing far from equlibrium maintained with the flow of electric current inside and outside the cell. The process of formation of the p11 band patterns was studied when two cells were placed closely and in parallel to each other under illumination. The mutual entrainment between the two cells was observed in the formation of the pattern, i.e., the two cells developed the periodic pH band pattern in common. To explain theoretically the entrainment phenomenon, we considered a simple situation where the cell is placed under an applied electrochemical force. The entrained pattern was described by reaction-diffusion type nonlinear equations with an additive term of the applied force. A criterion for the stability of the entrained solution was provided by solving the equations using perturbation method.