Changes in actin filament organization during pseudopod formation. 1997

E Lee, and E A Shelden, and D A Knecht
Department of Molecular and Cell Biology, University of Connecticut, Storrs, Connecticut 06269, USA.

Fluorescent phalloidin has been introduced into Dicytostelium amoebae 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.

UI MeSH Term Description Entries
D010590 Phalloidine Very toxic polypeptide isolated mainly from AMANITA phalloides (Agaricaceae) or death cup; causes fatal liver, kidney and CNS damage in mushroom poisoning; used in the study of liver damage. Phalloidin
D011554 Pseudopodia A dynamic actin-rich extension of the surface of an animal cell used for locomotion or prehension of food. Axopodia,Filopodia,Lamellipodia,Lobopodia,Microspikes, Cell Surface,Reticulopodia,Pseudopodium,Cell Surface Microspike,Cell Surface Microspikes,Lamellipodias,Microspike, Cell Surface,Surface Microspike, Cell,Surface Microspikes, Cell
D004023 Dictyostelium A genus of protozoa, formerly also considered a fungus. Its natural habitat is decaying forest leaves, where it feeds on bacteria. D. discoideum is the best-known species and is widely used in biomedical research. Dictyostelium discoideum,Dictyostelium discoideums,Dictyosteliums,discoideum, Dictyostelium
D000199 Actins Filamentous proteins that are the main constituent of the thin filaments of muscle fibers. The filaments (known also as filamentous or F-actin) can be dissociated into their globular subunits; each subunit is composed of a single polypeptide 375 amino acids long. This is known as globular or G-actin. In conjunction with MYOSINS, actin is responsible for the contraction and relaxation of muscle. F-Actin,G-Actin,Actin,Isoactin,N-Actin,alpha-Actin,alpha-Isoactin,beta-Actin,gamma-Actin,F Actin,G Actin,N Actin,alpha Actin,alpha Isoactin,beta Actin,gamma Actin
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D016296 Mutagenesis Process of generating a genetic MUTATION. It may occur spontaneously or be induced by MUTAGENS. Mutageneses
D017353 Gene Deletion A genetic rearrangement through loss of segments of DNA or RNA, bringing sequences which are normally separated into close proximity. This deletion may be detected using cytogenetic techniques and can also be inferred from the phenotype, indicating a deletion at one specific locus. Deletion, Gene,Deletions, Gene,Gene Deletions
D018274 Electroporation A technique in which electric pulses, in kilovolts per centimeter and of microsecond-to-millisecond duration, cause a loss of the semipermeability of CELL MEMBRANES, thus leading to ion leakage, escape of metabolites, and increased uptake by cells of drugs, molecular probes, and DNA. Depending on the dosage, the formation of openings in the cell membranes caused by the electric pulses may or may not be reversible. Electric Field-Mediated Cell Permeabilization,Irreversible Electroporation,Reversible Electroporation,Electropermeabilisation,Electric Field Mediated Cell Permeabilization,Electroporation, Irreversible,Electroporation, Reversible
D018995 Myosin Heavy Chains The larger subunits of MYOSINS. The heavy chains have a molecular weight of about 230 kDa and each heavy chain is usually associated with a dissimilar pair of MYOSIN LIGHT CHAINS. The heavy chains possess actin-binding and ATPase activity. Myosin Heavy Chain,Heavy Chain, Myosin,Heavy Chains, Myosin

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