Control by osmolarity and electric field strength of electro-induced gene transfer and protein release in fission yeast cells

A high electric pulse was applied to the uptake of DNA into cells, the sterilization of cells, and the release of protein from cells. These applications to fission yeast showed a strong dependence on both the osmolarity of pulsing sorbitol solution and the intensity of the electric pulse. In electroporation, high transformation efficiency was obtained with a wide range of sorbitol (0.6-1.6 M) at 10.0 kV/cm for about 5 ms. Furthermore, the highest efficiency was achieved in 1.5 M sorbitol at a higher strength, 12.5 kV/cm, although the cell survival rate dropped. The release of protein generally increased with increasing electric field strength, due mainly to leakage from dead cells under hypotonic conditions. However, protein was released significantly in 1.5 M sorbitol at a lower strength, 7.5 kV/cm, although a high survival rate was maintained. Thus, the application of the high electric pulse to fission yeast under hypertonic conditions increased the uptake and release of macromolecules controlled by the electric field strength.