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  • 1
    Electronic Resource
    Electronic Resource
    Dynamic aspects of the contractile system in Physarum Plasmodium: II. Contractility of triton cell models in accordance with the contraction and relaxation phases of the plasmodia (1986)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 6 (1986), S. 448-457 
    Details
    ISSN: 0886-1544
    Keywords: cytoplasmic fibril ; birefringence ; microfilament ; contraction-relaxation cycle ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The contractility of Physarum plasmodium was investigated using cell models that were prepared by treating thin-spread plasmodia with ice-cold 0.2% Triton X-100. Cell models obtained from the anterior regions of the thin-spread plasmodia in the contraction phase retained many birefringent cytoplasmic fibrils. The fibrils vigorously contracted on addition of ATP, inducing simultaneous contraction of the whole cell models. In contrast, cell models prepared from the anterior regions in the relaxation phase scarcely contained the birefringent fibrils and exhibited only weak contractility on addition of ATP. The posterior regions of the thinspread plasmodia, which were composed of ramified plasmodial strands, always retained many fibrils when treated with the Triton solution and showed intensive contraction on addition of ATP.SDS-polyacrylamide gel electrophoresis showed that the model was enriched for actin and myosin. About 40% of the actin was extracted from the plasmodium by the Triton treatment, while scarcely any myosin was extracted.Fragmin, a F-actin-fragmenting factor, caused the birefringent fibrils to diminish in the presence of Ca2+, but more than 30 minutes was required for their complete disappearance. The birefringent fibrils weakened by 30-minute fragmin treatment disappeared immediately on addition of ATP or AMP-PNP.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970060503
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  • 2
    Electronic Resource
    Electronic Resource
    Dynamic aspects of the contractile system in Physarum Plasmodium: I. Changes in spatial organization of the cytoplasmic fibrils according to the contraction-relaxation cycle (1986)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 6 (1986), S. 439-447 
    Details
    ISSN: 0886-1544
    Keywords: dynamics of actomyosin fibril ; microfilament bundle ; NBD-phallacidin ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Dynamic changes in the spatial organizations of cytoplasmic fibrils (microfilament bundles) related to the contraction-relaxation cycle in thin-spread plasmodia of Physarum polycephalum were investigated by fluorescence microscopy, where NBD-phallacidin was used to stain the fibrils, combined with polarizing light microscopy.The fibrillar organization in the anterior region, which consists of a fanlike spreading plasmodial sheet, strikingly changed according to the phase of the cycle. In the early stage of the contraction, as the endoplasm began to stream backward, the fibrils developed into a number of slender and flabby fibrils emanating from the inside of the cell membrane and the nodes. They became thicker and more straightforward fibrils running parallel to each other at the middle stage, and finally formed a thick framework consisting of a “polygonal network” near the tip of the migrating front and a “parallel array” in the inner part. In the relaxation phase, as the endoplasm streamed forward, the fibrillar framework disintegrated gradually and finally disappeared almost completely, remaining only around the nodes in some cases.The fibrillar patterns in the posterior region, which consists of ramified strands, showed no conspicuous rhythmic change with alternation of the streaming direction.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970060502
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  • 3
    Electronic Resource
    Electronic Resource
    A light and electron microscopic study of the flagellate-to-ameba conversion in the MyxomyceteStemonitis pallida (1977)
    Springer
    Protoplasma 91 (1977), S. 31-54 
    Details
    ISSN: 1615-6102
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The flagellate-to-ameba conversion process of the MyxomyceteStemonitis pallida was investigated with Nomarski optics and electron microscopy. The flagellate has two flagella, a long and a short one. When the water film containing the flagellates becomes very thin, they retract their flagella, usually the short one first and then the long one. The short flagellum is retracted by only one method, in which the sheath membrane of the flagellum fuses with the cell membrane, consequently causing the axoneme to be absorbed into the cytoplasm. Retraction of the long flagellum can be divided into four types. In all cases, fusion of the sheath membrane and the cell membrane takes place. The retracted axoneme of the long flagellum sometimes beats convulsively for about 10 minutes after retraction, and after 10–15 minutes it became indistinguishable as it was detached from the blepharoplast. Analysis of thin sections shows that the retracted axonemes disintegrate in the following squence: B-tubules, A-tubules, spokes, central microtubules. In almost all cells the degradation begins immediately after retraction and is completed within 90 minutes. Only on rare occasions, structures which seem to have been derived from retracted axonemes are observed in the ameba about 90 minutes after conversion. The basal bodies and cytoplasmic microtubules are a little more stable than the retracted axonemes. Some basal bodies of the short flagellum, whose C-tubules are affected, are present in the amebae more than 90 minutes after conversion. Cytoplasmic microtubules decrease in number and become shorter in the amebae after about 24 hours, when newly formed regions filled with flocculent material appear.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01284194
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  • 4
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    Actin cytoskeleton of resting bovine platelets (1990)
    Elsevier
    Details
    Publication Date: 1990-02-01
    Print ISSN: 0014-4827
    Electronic ISSN: 1090-2422
    Topics: Biology , Medicine
    Published by Elsevier
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  • 5
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    Dry Stress-Induced Phosphorylation ofPhysarumActin (1998)
    Elsevier
    Details
    Publication Date: 1998-01-01
    Print ISSN: 0006-291X
    Electronic ISSN: 1090-2104
    Topics: Biology , Chemistry and Pharmacology , Physics
    Published by Elsevier
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