title: Harmonic generation by yeast cells in response to low-frequency electric fields.
abstract: We report on harmonic generation by budding yeast cells (Saccharomyces cerevisiae, 10(8) cells/ml) in response to sinusoidal electric fields with amplitudes ranging from zero to 5 V/cm in the frequency range 10-300 Hz. The cell-generated harmonics are found to exhibit strong amplitude and frequency dependence. Sodium metavanadate, an inhibitor of the proton pump known as H+-ATPase, and glucose, a substrate of H+-ATPase, are found to increase harmonic production at low amplitudes while reducing it at large amplitudes. This P-type proton pump can be driven by an oscillatory transmembrane potential, and its nonlinear response is believed to be largely responsible for harmonic production at low frequencies in yeast cells. We find that the observed harmonics show dramatic changes with time and in their field and frequency dependence after perturbing the system by adding an inhibitor, substrate, or membrane depolarizer to the cell suspension.
authors.affiliation: Department of Physics and Texas Center for Superconductivity, University of Houston, Houston, Texas 77204-5005, USA.
authors.forename: D
authors.initials: D
authors.lastname: Nawarathna
authors.forename: J R
authors.initials: JR
authors.lastname: Claycomb
authors.forename: G
authors.initials: G
authors.lastname: Cardenas
authors.forename: J
authors.initials: J
authors.lastname: Gardner
authors.forename: D
authors.initials: D
authors.lastname: Warmflash
authors.forename: J H
authors.initials: JH
authors.lastname: Miller
authors.forename: W R
authors.initials: WR
authors.lastname: Widger
mesh_terms: D001683:Biological Clocks / Q000502:physiology* / Q000528:radiation effects; D002462:Cell Membrane / Q000502:physiology* / Q000528:radiation effects; D003198:Computer Simulation; D004307:Dose-Response Relationship, Radiation; D004574:Electromagnetic Fields; D015640:Ion Channel Gating / Q000502:physiology / Q000528:radiation effects; D008564:Membrane Potentials / Q000502:physiology* / Q000528:radiation effects; D008565:Membrane Proteins / Q000378:metabolism; D008954:Models, Biological; D017494:Proton Pumps / Q000502:physiology* / Q000528:radiation effects; D011829:Radiation Dosage; D012441:Saccharomyces cerevisiae / Q000502:physiology* / Q000528:radiation effects; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*
chemical_list: D008565:Membrane Proteins; D017494:Proton Pumps; D029701:Saccharomyces cerevisiae Proteins