Endogenous electrical currents in the water mold Blastocladiella emersonii during growth and sporulation

We have explored the pattern of electrical currents generated by single cells of the water mold Blastocladiella emersonii at several stages of its life cycle. Extracellular currents were measured with a vibrating probe constructed after the design of Jaffe and Nuccitelli [Jaffe, L.F.& Nuccitelli, R. (1974) J. Cell Biol. 63, 614-628]. In growing cells positive current, of the order of 1 μ A/cm2, enters the rhizoid and leaves from the thallus; circumstantial evidence suggests that protons carry much of the current. Sporulation is associated with reversal of the current pattern, such that positive current enters the thallus and leaves from the rhizoidal region; the ions that carry the current have not been identified. These current patterns appear to play a role in the spatial localization of fungal growth and development.