Modulation of cellular rhythm and photoavoidance by oscillatory irradiation in the Physarum plasmodium

We studied responses of cellular rhythm and light-induced movement to perio dic irradiation in a unicellular amoeboid organism, the Physarum plasmodium . The intrinsic frequency of the contraction rhythm, which is based on bioc hemical oscillations, became synchronized with the frequency of periodic ir radiation with light when both frequencies were close enough. In order to s tudy the role of the synchronization in light-induced movement, periodic ir radiation was applied to only part of the plasmodium. The rate of avoidance of light was modulated in the frequency band in which the synchronization occurred. The synchronization property of the contraction oscillation under lies the regulation of tactic movement in plasmodium. (C) 1999 Elsevier Sci ence B.V. All rights reserved.