The Journal of Cell Biology, Vol 87, 569-578, Copyright © 1980 by The Rockefeller University Press

ARTICLES

Active movement in vitro of bundle of microfilaments isolated from Nitella cell

S Higashi-Fujime

Subcortical fibrils composed of bundles of F-actin filaments and endoplasmic filaments are responsible for endoplasmic streaming. It is reported here that these fibrils and filaments move actively in an artificial medium containing Mg-ATP and sucrose at neutral pH, when the medium was added to the cytoplasm squeezed out of the cell. The movement was observed by phase-contrast microscopy or dark-field microscopy and recorded on 16-mm film. Chains of chloroplasts linked by subcortical fibrils showed translational movement in the medium. Even after all chloroplasts and the endoplasm were washed away by perfusion with fresh medium, free fibrils and/or filaments (henceforth, referred to as fibers) not attached to chloroplasts continued travelling in the direction of the fiber orientation. Sometimes the fibers formed rings and rotated. Chloroplast chains and free fibers or rings continued moving for 5-30 min at about half the rate of the endoplasmic streaming in vivo. Calcium ion concentrations < 10(-7) M permitted movement to take place. Electron microscopy revealed that both fibers and rings were bundles of F-actin filaments that showed the same polarity after decoration with heavy meromyosin.
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This article has been cited by other articles:

• Kachar, B (1985). Direct visualization of organelle movement along actin filaments dissociated from characean algae. Science 227: 1355-1357 [Abstract]  
• Higashi-Fujime, S. (1982). Active Movement of Bundles of Actin and Myosin Filaments from Muscle: A Simple Model for Cell Motility. Cold Spring Harb Symp Quant Biol 46: 69-75 [Abstract]  
• Allen, R. D., Travis, J. L., Hayden, J. H., Allen, N. S., Breuer, A. C., Lewis, L. J. (1982). Cytoplasmic Transport: Moving Ultrastructural Elements Common to Many Cell Types Revealed by Video-enhanced Microscopy. Cold Spring Harb Symp Quant Biol 46: 85-87 [Abstract]  

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