Microbioelectromagnetics

Higher education teachers: Kotnik Tadej

Subject description

Prerequisites:

Recommended prerequisites comprise basic knowledge of ordinary and partial differential equations (e.g. Mathematics 1-4 from 1st cycle academic programme Electrical Engineering), and basic knowledge of cell biology (secondary school level).

Content (Syllabus outline):

Biological cells in electric fields, resting and induced membrane voltage. Voltage-gated membrane channels, electrical stimulation of excitable cells. Electroporation of cell membrane.
Analytical derivation of induced membrane voltage in static electric fields: spherical cells (Schwan equation), cylindrical, spheroidal and ellipsoidal cells.
Analytical derivation of induced membrane voltage in time-varying electromagnetic fields. Generalized Schwan equation of the first and second order. Analysis of absorption of the field energy in the cell and its membrane.
Analytical derivation of voltage induced on membranes of intracellular ogranelles. Ratio between the voltage induced on the external and membrane and the internal membranes.
Numerical computation of induced membrane voltage in static electric fields: dense suspensions of spherical cells, irregularly shaped cells, clusters of electrically insulated and electrically connected cells.
Numerical computation of induced membrane voltage time-varying electromagnetic fields. Numerical modeling of electroporation and transport across the electroporated membrane.
Molecular dynamics simulations: lipid bilayed in the electric field, formation and resealing of transmembrane pores.
Experimental determination of membrane voltage. Potentiometric dyes, image acquisition and data processing. Experimental monitoring of opening and closing of voltage-gated channels and transport across them. Experimental monitoring of electroporation and transport across the electroporated membrane.
Electroporation in nature and its possible role in the evolution of microorganisms. Three biochemical mechanisms of horizontal gene transfer. Lightning as the cause of DNA release from irreversibly electroporated microorganisms, movement of released DNA in aqueous environment (electrophoresis) and DNA uptake by reversibly electroporated microorganisms.

Objectives and competences:

To gain the basic understanding of the effects of electric fields on biological cells. To acquire the basic knowledge of analytical, numerical, and experimental assessment of these effects. To understand the molecular basis of the functioning of voltage-gated membrane channels and the phenomenon of membrane electroporation.

Intended learning outcomes:

Knowledge and understanding: The students will gain the basic understanding of the effects of electric fields on biological cells. They will be able to assess these effects analytically, numerically, and experimentally. They will understand the functioning of voltage-gated channels and membrane electroporation.

Application: Independent understanding and analysis of effects of electric fields on the cell level, including the triggering of voltage-gated channels and cell membrane electroporation.

Reflection: The students will be able, for the known strength, duration and time course of the electric or electromagnetic fields, to assess the effects of exposure of biological cells to such fields.

Transferrable skills: Knowledge gained in numerical solving of differential equations using the finite elements and finite differences methods is of increasing use and importance in many areas of modeling and simulation in electrical and mechanical engineering, as well as in materials sciences. Molecular dynamics simulations are among the most rapidly progressing fields in molecular biophysics and biochemistry. Monitoring of membrane voltage and transmembrane transport by means of patch clamp and potentiometric methods are among the modern and widely used techniques in electrophysiology and cell biology.

Learning and teaching methods:

In case of sufficient number of enrolled students lectures throughout the semester, otherwise part-time lectures and part-time
self-study with regular meetings, tutorials with research work, seminar.

Study materials

1. Alberts B, Bray D, Hopkin K, Johnson AD, Lewis J, Raff M, Roberts K, Walter P. Essential Cell Biology, 4th edition. Garland Science, 2013.
2. Kotnik T, Pucihar G, Miklavčič D. Induced transmembrane voltage and its correlation with electroporation-mediated molecular transport. J. Membrane Biol. 236: 3-13, 2010.
3. Tombola F. Pathak MM, Isacoff EY. How does voltage open an ion channel? Annu. Rev. Cell Dev. Biol. 22:23-52, 2006.
4. Kotnik T, Miklavčič D. Theoretical evaluation of voltage inducement on internal membranes of biological cells exposed to electric fields. Biophys. J. 90: 480-491, 2006.
5. Kotnik T, Miklavčič D. Theoretical evaluation of the distributed power dissipation in biological cells exposed to electric fields. Bioelectromagnetics 21: 385-394, 2000.
6. Delemotte L, Tarek M. Molecular dynamics simulations of lipid membrane electroporation, J. Membr. Biol. 245: 531-543, 2012.
7. Kotnik T. Lightning-triggered electroporation and electrofusion as possible contributors to natural horizontal gene transfer. Phys. Life Rev. 10: 351-370, 2013.