Dynamic organization of ATP and birefringent fibrils during free locomotion and galvanotaxis in the plasmodium of Physarum polycephalum

Directed migration by a cell is a good phenomenon for studying intracellular coordination. Dynamic organization of both ATP and birefringent fibrils throughout the cell was studied in the multinuclear ameboid cell of the Physarum plasmodium during free locomotion and galvanotaxis. In a directionally migrating plasmodium, waves of ATP as well as thickness oscillations propagated from just inside the advancing front to the rear, and ATP concentration was high at the front on the average. In a DC electric field, locomotion was inhibited more strongly, ATP concentration decreased more, and birefringent fibrils were formed more abundantly at the anodal than at the cathodal side. Inside the cell there were a few undulations in the distributions of ATP and birefringent fibrils. In short, birefringent fibrils become abundant where ATP concentration decreases. The possible mechanism of the coordination in the directed migration and the implications of the scaling law are discussed.