title: Strong static magnetic field effects on yeast proliferation and distribution.
abstract: The present study focuses on the effects of gradient magnetic fields on the behavior of yeast, such as its proliferation and mass distribution, and evaluates the effects of magnetism on materials in the yeast culture system. Yeast, Saccharomyces cerevisiae, was incubated in a liquid medium under magnetic fields (flux density B = 14 T). When yeast in a tube was exposed to 9-14 T magnetic fields with a maximum flux density gradient of dB/dx = 94 T/m, where x is the space coordinate, the rate of yeast proliferation under the magnetic fields decreased after 16 h of incubation compared to that of the control group. The physical properties of the yeast culture system were investigated to discover the mechanism responsible for the observed deceleration in yeast proliferation under magnetic fields. Gas pressure inside the yeast culture flask was compared with and without exposure to a magnetic field. The results suggested that the gas pressure inside a flask with 6 T, 60 T/m slowly increased in comparison to the pressure inside a control tube. Due to the diamagnetism of water (medium solution) and yeast, the liquid surface distinctly inclined under gradient magnetic fields, and the hydrostatic force in suspension was strengthened by the diamagnetic forces. In addition, magnetophoresis of the yeast cells in the medium solution exhibited localization of the yeast sedimentation pattern. The roles of magnetically changed gas-transport processes, hydrostatic pressures acting on the yeast, and changes in the distribution of the yeast sedimentation, as well as the possible effects of magnetic fields on yeast respiratory systems in the observed disturbance of the proliferation are discussed.
authors.affiliation: Department of Biomedical Engineering, Graduate School of Medicine, University of Tokyo, Hongo 7-3-1, Bunkyo-Ku, Tokyo 113-0033, Japan. iwasaka@medes.m.u-tokyo.ac.jp
authors.forename: Masakazu
authors.initials: M
authors.lastname: Iwasaka
authors.forename: Masateru
authors.initials: M
authors.lastname: Ikehata
authors.forename: Junji
authors.initials: J
authors.lastname: Miyakoshi
authors.forename: Shoogo
authors.initials: S
authors.lastname: Ueno
mesh_terms: D049109:Cell Proliferation; D002498:Centrifugation; D003470:Culture Media; D005947:Glucose / Q000494:pharmacology; D006874:Hydrostatic Pressure; D008280:Magnetics; D010100:Oxygen / Q000494:pharmacology; D010461:Peptones / Q000494:pharmacology; D012441:Saccharomyces cerevisiae / Q000166:cytology* / Q000187:drug effects; D013535:Suspensions
chemical_list: D003470:Culture Media; D010461:Peptones; D013535:Suspensions; D005947:Glucose; D010100:Oxygen