抄録
We report the time course of nonlinear dielectric responses in living and dead cells of the budding yeast Saccharomyces cerevisiae with changes in their concentrations in suspension. To measure nonlinear dielectric responses, a sinusoidal electric field (1.2V/cm, 14Hz) was applied to the outer electrodes of a 4-terminal system and the response waveform was captured across the inner electrodes. Fourier transform permits determination of the harmonics or other frequencies not present in the exciting waveform. We measured the response waveform for 3 min and showed a relationship between the time course and relative harmonic contents. The results indicated that in living cells, the third harmonic content increased and the fifth harmonic content decreased with increasing concentration. The relative harmonic content of dead cells, however, remained similar regardless of the yeast cell concentration. The differences between living and dead cells became more conspicuous as the concentration increased. Observation of the responses permitted us to distinguish between living and dead cells.
