Correlation of electrical current influx with nuclear position and division inFunaria caulonema tip cells

Summary Ionic currents around caulonema tip cells of the filamentous protonema of the mossFunaria hygrometrica were examined using a nonintrusive vibrating microelectrode to map electrical current before and during mitosis. Tip cells in interphase generate inward electrical currents that are maximal at the nuclear region. These currents remain concentrated over the nucleus as it migrates forward maintaining a constant distance from the growing tip. Just prior to mitosis this inward current increases twofold. During mitosis and cytokinesis current at the nuclear zone increases to four times the resting level and fluctuates, falling to zero after cell plate fusion with parental walls. The locus of outward current could not be dectected. These results suggest that plasma membrane ion currents may regulate both nuclear positioning and subsequent temporal and spatial control of cell division.