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  • 1
    Electronic Resource
    Electronic Resource
    Ultrastructure and Rapid Axopodial Contraction of a Heliozoa, Raphidiophrys contractilis Sp. Nov. (1995)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 42 (1995), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . In the present study, we isolated a species of heliozoans from a brackish pond in Shukkeien Garden, Naka-ku, Hiroshima City, Japan. Electron-microscopic observations showed that the axonemal microtubules in this heliozoan constituted a complex pattern of hexagons and triangles. By applying SDS-polyacrylamide gel electrophoresis and subsequent immunoblotting, molecular weights of α and β-tubulins were determined to be 48 and 45 kDa, respectively. X-ray microanalysis demonstrated that the numerous scales coating the cell body surface were silicic structures. Size and shape of the cell body and the scales were examined and compared with other known species of heliozoans, which led us to conclude that this is a new species belonging to the genus Raphidiophrys. This heliozoan was also found to carry out rapid axopodial contraction during food uptake at a velocity of about 1 mm/s. With reference to this characteristic contractile behavior, this new species was named Raphidiophrys contractilis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1995.tb01581.x
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  • 2
    Electronic Resource
    Electronic Resource
    Electron Microscopy of the Ectoplasm and the Proboscis in Didinium nasutum (1965)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 12 (1965), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SYNOPSIS. A morphological study on the ectoplasm and the proboscis in the ciliate Didinium nasutum, has been performed by means of an electron microscope. The ectoplasm and the endoplasm of Didinium are separated by a fibrous layer. In addition to the ciliary apparatus and the filament system, the ectoplasm is characterized by having ectoplasmic vacuoles enclosing cross-striated bodies and by having small rods surrounding the ciliary basal body.The filament system is composed of 4 types of tubular filaments: primary filaments originating from the basal body, secondary ones coursing longitudinally along the cell periphery, tertiary ones going down in cylindrical arrays from the periphery of the proboscis into the endoplasm, and finally kinetosomal ones from the base of the basal body into the endoplasm through the newly found pore of the fibrous layer.The fine morphology of the trichites in the proboscis is elucidated three-dimensionally and illustrated schematically. Moreover, the correlation among the small rod, ectoplasmic vacuole and trichite is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1965.tb03227.x
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  • 3
    Electronic Resource
    Electronic Resource
    Electron Microscopy of the Longitudinal Fibrillar Bundle and the Contractile Fibrillar System in Spirostomum ambiguum (1963)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 10 (1963), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SYNOPSIS. A study of the ‘longitudinal fibrillar bundle’ (LFB) and the ‘contractile fibrillar system’ (CFS) of a large protozoan ciliate, Spirostomum ambiguum, has been performed by means of an electron microscope. A system of sub-pellicular fibrils has been newly found and its function is discussed. Each LFB runs parallel with a longitudinal row of ciliary bases. It seems to be identical with the so-called kinetodesma. It is composed of tubular fibrils arranged in layered sheets, each of which contains 13 to 35 fibrils with the same diameter as the intra-ciliary fibrils and has a close connection to each of the ciliary bases. The CFS lies on a transitional plane between ectoplasm and endoplasm of the organism and forms a cobweb-like system of myofibrils as a whole. It stands in an intimate relationship with a characteristic vacuolar system. In a peristomial field, the fibrous structures are interrupted and somewhat thickened. A sub-pellicular system is composed of minute fibrils 20 to 26 mμ in diameter. The fibrils run parallel with each other in an antero-posterior direction, immediately beneath the inner pellicular membrane.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1963.tb01689.x
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  • 4
    Electronic Resource
    Electronic Resource
    The Ultrastructure of Contractile Tubules in the Heliozoon Actinophrys sol and Their Possible Involvement in Rapid Axopodial Contraction (2001)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 48 (2001), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . We employed an improved fixation procedure for electron microscopy using ruthenium red, and found a bundle of contractile tubules inside the axopodia of the heliozoon Actinophrys sol. Upon food uptake, the tubules shorten and transform into a mass of small granules when rapid axopodial contraction occurs, suggesting that these structures are involved in the process of axopodial contraction. The relationship between transformation of the contractile tubules and accompanying disassembly of the axonemal microtubules was studied by examining the ultrastructure of the contractile tubules after disassembly of the microtubules was artificially induced by cold or colchicine treatment. Granulation of the contractile tubules was induced by cold but not by colchicine treatment. During recovery from cold treatment, granular forms of the contractile tubules became re-elongated and their initial tubular appearance was restored. These results suggest that the contractile tubules in heliozoon axopodia play a role in repetitive cytoplasmic contraction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.2001.tb00187.x
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  • 5
    Electronic Resource
    Electronic Resource
    Structure and function of the cytoskeleton in heliozoa: I. Mechanism of rapid axopodial contraction in Echinosphaerium (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 14 (1989), S. 288-301 
    Details
    ISSN: 0886-1544
    Keywords: axopodium ; microtubules ; X-body ; receptor site ; contraction ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In the heliozoan Echinosphaerium, rapid axopodial contraction often occurs during food capturing. In morphological studies, it has been considered that rapid contraction is caused by conformation is change of the X-body. We determined that reaction sites or receptors for anion exchange resin, which can induce rapid contraction, were located in every region of the axopodium. However, the probability of locating sites where contraction was induced was lower in the middle region than in the distal region of the axopodium. In cases in which contraction was not induced by resin placed in the middle region of the axopodium, so-called bead formation was induced instead. At the fine structural level, only granulated forms of the X-body were observed in this beading region. These results suggest that rapid contraction results from disassembly of axonemal microtubules and the simultaneous contraction of the X-body and that bead formation represents a stage when only the X-body contracts. Furthermore, effects of metabolic inhibitors and Ca2+ channel blockers revealed that contraction of the X-body did not depend on the supply of adenosine triphosphate, but on Ca2+ influx. Ultrastructural observations revealed that the mass of the granulated X-body was aggregated into the proximal region of the axopodium, suggesting that the X-body might be associated with the undercoat of axopodial membrane or the axonemal microtubules themselves.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970140214
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  • 6
    Electronic Resource
    Electronic Resource
    Cell model contraction in the ciliate spirostomum (1988)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 9 (1988), S. 278-282 
    Details
    ISSN: 0886-1544
    Keywords: myoneme ; microtubule ; Ca2+ ions ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: As the species name indicates, the large heterotrichous ciliate Spirostomum ambiguum is characterized by a twisting contraction of the cell body that is easily triggered by various kinds of external stimuli. On the basis of morphological studies, contraction and extension of this organism have been considered to result from antagonistic actions of myoneme and microtubular ribbons. After many trials, we have succeeded in preparing cell models to examine induced contractions and extensions of the cell body. The contraction of this model was induced by increasing the free Ca2+ concentrations even in the absence of Mg-ATP and was reversed by adding Mg-ATP without Ca2+. Using dynein ATPase inhibitors such as vanadate and ATP analogs, furthermore, the experiments revealed that the ATPase that generated the force between the two neighboring microtubular ribbons might be a dynein-like ATPase.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970090310
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