Elsevier

Experimental Cell Research

Volume 235, Issue 1, 25 August 1997, Pages 295-299
Experimental Cell Research

SHORT NOTE
Changes in Actin Filament Organization during Pseudopod Formation

https://doi.org/10.1006/excr.1997.3665Get rights and content

Abstract

Fluorescent phalloidin has been introduced intoDicytosteliumamoebae in order to visualize dynamic changes in the localization of F-actin during pseudopod extension. Phalloidin was initially localized to the peripheral cortex of the cell. Newly formed pseudopods were not fluorescent, indicating that phalloidin was tightly bound to existing F-actin filaments and could not rapidly relocalize to newly formed filaments. As pseudopod extension proceeded, the fluorescent signal disappeared from the region directly underlying the expansion zone, leaving a gap in the actin cortex. Similar results were obtained in both wild-type cells and those lacking myosin II heavy chain. The disappearance of the fluorescent signal from the cortical region underlying the new pseudopod is presumed to be due to breakdown of the actin cortex and dispersion of the remnants. These results suggest that new pseudopods are not built upon the existing actin cortex but rather that the cortex is locally solated as part of the construction of the new actin network.

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    1

    Current address: Department of Anatomy and Cell Biology, 4769 Medical Science II Building, The University of Michigan Medical School, Ann Arbor, MI 48109-0616.

    2

    To whom correspondence and reprint requests should be addressed at U-125, Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT 06269. Fax: (860) 486-4331. E-mail: [email protected].

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