INFORMATION PROPAGATION BY SPATIOTEMPORAL PATTERN CHANGE OF CA2-POLYCEPHALUM WITH REPULSIVE STIMULATION( CONCENTRATION THROUGHOUT PHYSARUM)

The development of a spatio-temporal pattern of Ca2+ concentration (Ca 2+ pattern) in the plasmodium of Physarum polycephalum during repulsiv e response was studied using fura-2. In the migrating cell, the gradie nt of the Ca2+ concentration (Ca2+ gradient) immediately showed a decr ease in local concentration in the area (S-site) stimulated by 50 mM K Cl. The concentration rose and then decreased in a site neighboring th e S-site. This transient increase of Ca2+ concentration, the duration of which was approx. 10 minutes, was propagated to the site most dista nt from the S-site. There, the Ca2+ concentration gradually rose and r emained at a high level. Twenty-five minutes after stimulation, a new Ca2+ gradient was established throughout the plasmodium. The migratory direction of the cell as a whole then changed. In this process, altho ugh the period of Ca2+ oscillation changed at the S-site, this change was only local to the site. During the information processing of the l ocal repulsive stimulus, the transient Ca2+ increase propagated the lo cal information about the stimulus to the non-stimulation sites (NS-si tes), leading to the generation of a new pattern and the start of coor dinated migration of the plasmodium.