AC IMPEDANCE MEASUREMENTS ON CHARA-CORALLINA .2. CAN THE PRESENCE OF PLASMALEMMASOMES BE DETECTED

Impedance measurements on cells of Chara corallina at frequencies of 10-10(2) Hz were used to investigate dielectric and geometrical properties of the plasmalemma and tonoplast at different longitudinal positions along the cylindrical surface of the cells. Large (100%) spatial variations occurred in the measured capacitance of some individual cells. Further, for spatially uniform cells, a 100% variation (from cell to cell) in capacitance was observed. Variations in capacitance (at 10-10(2) Hz) could be partially attributed to variations in: (i) the conductance of the series conductance element, (ii) the dielectric/geometrical properties of the tonoplast and (iii) the conductance of the cell membranes. However, we attribute a substantial part of the variations in capacitance to variations in the area of the plasmalemma per unit area of cell surface arising from extensive folding of the plasmalemma such as that found in plasmalemmasomes (charasomes).