The interaction of electric and magnetic fields with biological materials
In the course of the work on the interactions of electric and magnetic fields with biological materials both living and dead, 'it was noticed that published dielectrophoretic yield curves for biological cells showed unexplained deviations in the region of 2kHz which is the proton magnetic resonance frequency in a typical laboratory ambient magnetic field. The exact value is 2.13 kHz for a field of 50 UT. The results of preliminary dielectrophoretic and dielectric measurements show features at frequencies which correspond to the NMR condition for that value of steady magnetic field in which the measurements were made. Very sharp dielectric loss peaks were found corresponding to 1H, 31 p, 23Na, 35C1 amd 39K resonances. The electron spin resonance also showed up in the dielectric loss. The onset plus NMR conditions of these resonances commences at the value of the steady magnetic field strength such that one quantum of magnetic flux (2.07 x 10-15 Wb) would link the cross-sectional area of a single biological cell or pair of cells. Approximately 1.0 gauss or 0.5 gauss (100iT or 50pT) respectively in the case of 5um diameter yeast cell. Growing cultures of the yeast cells in fields which satisfy the proton NMR conditions as a function of temperature results in a slight reduction in the mean generation time (MGT). Comparison of this with the dielectric constant and loss increments at the corresponding temperatures showed that when the MGT is least, the cells are dividing most rapidly and the dielectric increments are greatest. Steps in the voltage-current characteristic of a pearlchain of yeast cells were found to occur for a few minutes around the time of cytokinesis as they were observed under phase contrast microscope. The cells prepared for synchronous division were collected by dielectrophoresis into a one micron gap between two point electrodes mounted on a microscope slide. Steps were observed about 3 to 4 hours later at ambient temperature. The mean generation time is 4 hours. An emission of a radio frequency signal from yeast cells in the region of 7 MHz and in the range of 50 MHz - 80 MHz were found to occur about a mean generation time after starting the incubation of the cells for synchronous growth. All these effects were only observed on the live yeast cells and never observed in experiments using killed yeast cells under the conditions otherwise same in all aspects.