Measurement of membrane potentials in Neurospora.

Microelectrodes were used to record intracellularly from the filamentous fungus Neurospora crassa. Under standard conditions membrane potentials averaged 127 mv, inside negative. The potentials were potassium-sensitive, and depended upon the distance of the cells from the growing margin of the colony. In addition, the potentials were quickly reduced to about 30 mv in the presence of low concentrations of sodium azide or the polyene antibiotic nystatin.