title: Orientation of paramecium swimming in a DC magnetic field.
abstract: We found that a ciliated protozoan, Paramecium, swam perpendicular to a static (DC) magnetic field (0.68 T). The swimming orientation was similar even when the ionic current through the cell membrane disappeared after saponin treatment. To determine the diamagnetic anisotropy of intracellular organs, macronuclei, cilia, and secretory vesicles, trichocysts, were selectively isolated. Both cilia and trichocysts tended to align their long axis parallel to the magnetic field (0.78 T). Paramecium mutants that lack trichocysts also swam perpendicular to the magnetic field, although the proportion fraction was smaller than the normal population. Since large numbers of cilia and trichocysts are arranged at right angles to the long axis of the cell, the diamagnetic anisotropies of cilia and trichocysts cause the long axis of the cell to align perpendicular to the magnetic field. In contrast to the DC magnetic field, an alternative (AC) magnetic field (60 Hz, 0.65 T) had almost no effect on the swimming orientation of Paramecium.
authors.affiliation: Division of Biophysical Engineering, Graduate School of Engineering Science, Japan. nakaoka@bpe.es.osaka-u.ac.jp
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Nakaoka
authors.forename: Ryutaro
authors.initials: R
authors.lastname: Takeda
authors.forename: Kikuo
authors.initials: K
authors.lastname: Shimizu
mesh_terms: D000818:Animals; D016880:Anisotropy; D002460:Cell Line; D002923:Cilia / Q000502:physiology / Q000528:radiation effects / Q000648:ultrastructure; D004574:Electromagnetic Fields; D008280:Magnetics; D015388:Organelles / Q000502:physiology / Q000528:radiation effects / Q000648:ultrastructure; D010247:Paramecium / Q000145:classification / Q000166:cytology / Q000502:physiology* / Q000528:radiation effects*; D016805:Paramecium tetraurelia / Q000145:classification / Q000166:cytology / Q000502:physiology / Q000528:radiation effects; D015203:Reproducibility of Results; D012503:Saponins / Q000378:metabolism / Q000494:pharmacology; D012680:Sensitivity and Specificity; D013550:Swimming / Q000502:physiology*
chemical_list: D012503:Saponins