title: Development of an apparatus to control load by electromagnet for a motility system in vitro.
abstract: We developed an electromagnet to perform quick changes in load in the motility system consisting of myosin molecules attached to a magnetizable bead and actin filaments The electromagnet was combined with an inverted microscope and load could be quickly changed under optical observation. The magnetic field was generated by high electric current (6V, 0-125A) and the maximum field was 8,000 Oe. The maximum force exerted on a bead was 80pN at 2.5mm distance from a magnet. The change in force was 0.48% at the distance of 5.0mm from the magnet when a bead moved longitudinally for 30microm. The time to change load was about 20ms. The movements of a bead in water were recorded by video when step changes in magnetic field were applied and it was shown that a bead exactly followed the change in force. This apparatus is very much useful to analyze the transient changes in the movement of a bead, if the movement is relatively slow as in the interaction between actin and myosin from molluscan smooth muscle.
authors.affiliation: Department of Biology, Faculty of Science, Kobe University, Nada-ku, Kobe 657-8501, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Watari
authors.forename: Akira
authors.initials: A
authors.lastname: Ono
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Ishii
authors.forename: Huang
authors.initials: H
authors.lastname: Zhenli
authors.forename: Shinichi
authors.initials: S
authors.lastname: Miyake
authors.forename: Teizo
authors.initials: T
authors.lastname: Tsuchiya
mesh_terms: D008841:Actin Cytoskeleton / Q000737:chemistry; D000199:Actins / Q000737:chemistry; D000818:Animals; D055590:Electromagnetic Phenomena / Q000295:instrumentation* / Q000379:methods; D066298:In Vitro Techniques; D008280:Magnetics; D018715:Microscopy, Video; D009068:Movement; D009119:Muscle Contraction; D009130:Muscle, Smooth / Q000378:metabolism; D015879:Myosin Subfragments / Q000737:chemistry; D009218:Myosins / Q000737:chemistry; D010827:Physiology / Q000295:instrumentation* / Q000379:methods*; D013997:Time Factors
chemical_list: D000199:Actins; D015879:Myosin Subfragments; D009218:Myosins