Spinning response of yeast cells to rotating electric fields

The frequency-dependent rotation or spinning motion of yeast cells subjected to a fourpole rotating electric field was examined over a very wide frequency range (500 Hz to 500 MHz). In the lower frequency range (500 Hz – 700 KHz) the yeast cells were observed to spin in a direction counter to the applied field, with a small peak at about 600 Hz and a more pronounced one at 20 KHz. For frequencies above 700 KHz the spinning of the cells switched direction from counter-field to co-field, with a maximum in the rotation rate at about 70 MHz and a subpeak at 20 MHz. The rate was also observed to exhibit a square dependence on the magnitude of the applied rotating field.