ISSN:
0886-1544
Keywords:
Dictyostelium discoideum
;
electron microscopy
;
indirect immunofluorescence
;
monoclonal antibodies
;
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Medicine
Notes:
Cytoskeletons were prepared from vegetative amoebae of Dictyostelium discoideum by extraction with Triton X-100. The cytoskeletons were suspended in buffers known to induce the assembly or disassembly of myosin filaments. The samples were fixed, and thin sections were examined by transmission electron microscopy. In both types of buffers, myosin-containing cytoskeletons exhibited a ring of densely staining proteinaceous material within the cortical filament matrix; this ring was not observed in myosin-free cytoskeletons. When myosin-containing cytoskeletons were placed in buffers that induced myosin polymerization, the ring appeared as an array of rodlike filaments approximately 13 nm wide and up to 0.5 μm in length - dimensions appropriate for myosin thick filaments. If ATP was added to cytoskeletons containing such filaments, the cytoskeletons contracted and the ring of filaments disappeared. ATP-induced contraction of cytoskeletons was also visualized by indirect immunofluorescence by using monoclonal antibodies to Dictyosielium myosin. All data were consistent with the identification of the protein ring seen by electron microscopy as cortical myosin. Its location and organization were appropriate for the production of cortical contraction through a sliding filament mechanism.
Additional Material:
7 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/cm.970070402
