Abstract
Permittivity was measured for rice (Oryza saliva L. japonica) cell suspension in the frequency range from 0.2 to 20 MHz. A good linear correlation (R=0.999) was observed between the permittivity at 0.41 MHz and the cell density. A decrease of the permittivity of cell suspension through a freezing-thawing process was observed and this seemed to reflect a mechanical damage on the plasma membrane of the cell. The intact cell ratio without the damage on the plasma membrane was estimated from the permittivity and was compared with a viability calculated from TTC (2, 3, 5-triphenyltetrazolium chloride) reduction assay at various freezing conditions. Effects of dimethylsulfoxide (DMSO) concentration, as a cryoprotectant, and cooling rate agreed between the intact cell ratio and TTC viability in their trends, although a quantitative discrepancy was observed between the two indices. Water permeability was also measured by permittivity to be 0.008 and 0.02 [pm/s/Pa] at 25℃ for rice and grape (Vitis sp) cells, respectively.
