Orientation of elongated cells in ac electromagnetic fields with frequencies up to 150 MHz

Abstract

Electro-orientation measurements were performed in a frequency range of 5–150 MHz on suspensions of untreated cells of Schizosaccharomyces pombe and cells treated with heat or chemical noxes. Three types of orientation for living cells could be observed: one with the long axis parallel to the field lines, one with the long axis perpendicular to the external field and one with the axis perpendicular to the plane of observation, i.e. the cells standing upright along their long axis. Living and non-living yeasts exhibit two opposite extrema of orientation at two typical frequencies. Investigations were performed to determine whether the degree of orientation at these two selected frequencies could be used as a screening test for the physiological state of cells. Furthermore, the experimental results were compared with model calculations, providing at least an approximate description of a typical orientation spectrum of yeast cells.