Jiří Pokorný

ELECTROMAGNETIC ACTIVITY OF YEAST CELLS IN THE M PHASE

Electromagnetic activity around yeast mitotic cells (Saccharomyces cerevisiae) was measured in the frequency range 8–9 MHz and special care was taken to extract reliable information from the raw signals. The characteristic of cold-sensitive tubulin mutants tub2-401 and tub2-406, which come to arrest before mitosis at a restrictive temperature (14°C) and which re-enter mitosis upon a shift back to a permissive temperature (28°C), was used to prepare synchronized mitotic cells. Immunofluorescence microscopy using an antitubulin antibody was used to analyze microtubular structures. The arrested tub2-401 mutant that had back-shifted to permissive temperature displayed no microtubules and no electromagnetic activity around the cells. In contrast, the arrested cells of the mutant tub2-406 displayed developed, but aberrant, nonfunctional microtubules and a high electromagnetic activity around the cells. The electromagnetic activity around the arrested mutant tub2-401 back-shifted to permissive temperature peaks at four time points which may coincide with (i) formation of the mitotic spindle, (ii) binding of chromatids to kinetochore microtubules, (iii) elongation of the spindle in anaphase A, and (iv) elongation of the spindle in anaphase B. The profile of the electromagnetic activity around the synchronized mutant tub2-406 at permissive temperature seems to be delayed by the time required for aberrant nonfunctional microtubules to be depolymerized. Experimental results presented in this paper support Pohls idea of existence of the electromagnetic field around yeast cells.

Microelectronic sensors for measurement of electromagnetic fields of living cells and experimental results

Microelectronic sensors are used for measurements of electromagnetic fields generated by synchronized cultures of yeast cells. Cold sensitive mutant tub2-401 of Saccharomyces cerevisiae is used. The measured electromagnetic signals in the frequency range from 8 to 9 MHz are compared with evolution of the reassembled microtubules. The detected signals peak in the time interval 25-30 min and 45-60 min after the release of the cells from the restrictive to the permissive temperature. The first maximum corresponds to the stage when the mitotic spindle is formed and binds chromatids. The second maximum is measured when the processes of anaphase A and of anaphase B take place.

High-frequency electric field and radiation characteristics of cellular microtubule network

Microtubules are important structures in the cytoskeleton, which organizes the cell. Since microtubules are electrically polar, certain microtubule normal vibration modes efficiently generate oscillating electric field. This oscillating field may be important for the intracellular organization and intercellular interaction. There are experiments which indicate electrodynamic activity of variety of cells in the frequency region from kHz to GHz, expecting the microtubules to be the source of this activity. In this paper, results from the calculation of intensity of electric field and of radiated electromagnetic power from the whole cellular microtubule network are presented. The subunits of microtubule (tubulin heterodimers) are approximated by elementary electric dipoles. Mechanical oscillation of microtubule is represented by the spatial function which modulates the dipole moment of subunits. The field around oscillating microtubules is calculated as a vector superposition of contributions from all modulated elementary electric dipoles which comprise the cellular microtubule network. The electromagnetic radiation and field characteristics of the whole cellular microtubule network have not been theoretically analyzed before. For the perspective experimental studies, the results indicate that macroscopic detection system (antenna) is not suitable for measurement of cellular electrodynamic activity in the radiofrequency region since the radiation rate from single cells is very low (lower than 10⁻²⁰ W). Low noise nanoscopic detection methods with high spatial resolution which enable measurement in the cell vicinity are desirable in order to measure cellular electrodynamic activity reliably.

Cancer physics: diagnostics based on damped cellular elastoelectrical vibrations in microtubules

This paper describes a proposed biophysical mechanism of a novel diagnostic method for cancer detection developed recently by Vedruccio. The diagnostic method is based on frequency selective absorption of electromagnetic waves by malignant tumors. Cancer is connected with mitochondrial malfunction (the Warburg effect) suggesting disrupted physical mechanisms. In addition to decreased energy conversion and nonutilized energy efflux, mitochondrial malfunction is accompanied by other negative effects in the cell. Diminished proton space charge layer and the static electric field around the outer membrane result in a lowered ordering level of cellular water and increased damping of microtubule-based cellular elastoelectrical vibration states. These changes manifest themselves in a dip in the amplitude of the signal with the fundamental frequency of the nonlinear microwave oscillator—the core of the diagnostic device—when coupled to the investigated cancerous tissue via the near-field. The dip is not present in the case of healthy tissue.

Endogenous Electric Field and Organization of Living Matter

Microtubules in eucaryotic cells form electrically polar structures, which satisfy conditions for excitation, energy condensation, and generation of endogenous electromagnetic field with strong electric near zone component. Large energy supply connected with continuous rebuilding of the microtubular structure and very likely with activity of motor proteins, and interfacial slip layer at the microtubule surface protecting vibrations in microtubules from viscous damping of the cytosol are important conditions for excitation and formation of coherent state. Generated electric field can exert a driving force for directed transport. The Wiener-Lévy process with symmetry breaking is used to describe motion of molecules and charges. Motion of molecules with diameter 1 and 5 nm at distances up to 50 nm is analysed. Transport driven by the electric field with inseparable thermal component has greater probability to reach the target than transport by thermal motion itself. Transport of electrons display similar dependence. Probability of any action depending on the ratio of the random and of the deterministic component of motion should be high enough to provide small number of errors but sufficiently low to comply with requirements for evolutionary changes.

CONDITIONS FOR COHERENT VIBRATIONS IN THE CYTOSKELETON

Mechanism of organization and order in biological systems is not satisfactorily explained yet. Biophysical theories predicted that coherent endogenous electric field of high frequency can play a significant role in organization. The polarity of vibration structures, spectral energy transfer caused by nonlinearities, and energy supply can lead to energy condensation and excitation of coherent states. These conditions are satisfied in the polymer structures of the cytoskeleton, in particular, in the microtubules as follows from experimental findings. Nonetheless, experimental verification of energy condensation and coherent vibrations in the cytoskeleton is still missing.

Electric field around microtubules

Abstract Living cells are organized by the cytoskeleton with a fundamental role of microtubules. The mechanisms of organization are largely unknown. We analyze the vibrations in the microtubules which are polar and are accompanied by polarization waves. Oscillating electric field generated around microtubules can be as high as 10 5 Vm −1 and may have an important role in information system and mass transport in living cells. Energy from hydrolysis of guanosine triphosphate (GTP) stored in microtubules can excite the vibrations above thermodynamic equilibrium level.

Electromagnetic Field of Microtubules: Effects on Transfer of Mass Particles and Electrons

Biological polar molecules and polymer structures with energy supply (such as microtubules in the cytoskeleton) can get excited and generate an endogenous electromagnetic field with strong electrical component in their vicinity. The endogenous electrical fields through action on charges, on dipoles and multipoles, and through polarization (causing dielectrophoretic effect) exert forces and can drive charges and particles in the cell. The transport of mass particles and electrons is analyzed as a Wiener-Lévy process with inclusion of deterministic force (validity of the Bloch theorem is assumed for transport of electrons in molecular chains too). We compare transport driven by deterministic forces (together with an inseparable thermal component) with that driven thermally and evaluate the probability to reach the target. Deterministic forces can transport particles and electrons with higher probability than forces of thermal origin only. The effect of deterministic forces on directed transport is dominant.

ENDOGENOUS ELECTROMAGNETIC FORCES IN LIVING CELLS: IMPLICATIONS FOR TRANSFER OF REACTION COMPONENTS

The mechanisms of order in living cells and in particular of the space–time order of chemical reactions are largely unknown. Directed transport of components to a reaction region cannot be explained by Brownian motion, which is disordered and increases entropy of the system. Besides transport by the motor proteins along microtubules, the endogenous electromagnetic field can provide translation motion of reaction components. This forced translation motion can have a high degree of certainty to reach the target region.

Measurement of Electrical Oscillations and Mechanical Vibrations of Yeast Cells Membrane Around 1 kHz

Fröhlich postulated coherent polar oscillations as a fundamental biophysical property of biological systems. Recently, Pelling et al. (2004, 2005) detected mechanical vibrations of yeast cell membrane with atomic force microscope (AFM) and analyzed by Fourier analysis in the frequency range 0.5–2 kHz with amplitudes of the order of 1 nm. This article describes the measurement of electric activity of yeast cells in the acoustic frequency range and of mechanical vibrations of cell membrane. Spectrum analyzer and electrically and electromagnetically screened box with point sensor and amplifiers fed by batteries were used for measurement of synchronized and non synchronized tubulin mutants of yeast cells. We show that the electric activity of synchronized cells in the M phase is greater that of non synchronized cells. That corresponds to the findings of Pohl et al. (1981). Obtained results of measurement of cell electric activity are in good agreement with AFM findings.