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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 43 (1996), S. 0 
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . Tetrahymena thermophila mutants homozygous for the oad mutation become nonmotile when grown at the restrictive temperature of 39° C. Axonemes isolated from nonmotile oad mutants (oad 39° C axonemes) lack approximately 90% of their outer dynein arms and are deficient in 22S dynein. Here we report that oad 39° C axonemes contain 40% of the 22S dynein heavy chains that wild-type axonemes contain and that oad axonemes do not undergo ATP-induced microtubule sliding in vitro. Wild-type 22S dynein will bind to the outer arm position in oad axonemes and restore ATP-induced microtubule sliding in those axonemes. Unlike wild-type 22S dynein, oad 22S dynein does not bind to the outer arm position in oad axonemes. These data indicate that the oad mutation affects some component of the outer arm dynein itself rather than the outer arm dynein binding site. These data also indicate that oad axonemes can be used to assay outer dynein arm function.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 38 (1991), S. 0 
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Dynein arms and isolated dynein from Paramecium tetraurelia ciliary axonemes are comparable in structure, direction of force generation, and microtubule translocation ability to other dyneins. In situ arms have dimensions and substructure similar to those of Tetrahymena. Based on spoke arrangement in intact axonemes, arms translocate axonemal microtubules in sliding such that active dynein arms are (-) end directed motors and the doublet to which the body and cape of the arms binds (N) translocates the adjacent doublet (N+1) upward. After salt extraction, based on ATPase activity, paramecium dynein is found as a 22S and a 14S species. the 22S dynein is a three-headed molecule that has unfolded from the in situ dimensions; the 14S dynein is single headed. Both dyneins can be photocleaved by UV light (350 nm) in the presence of Mg2-, ATP and vanadate; the photocleavage pattern of 22S dynein differs from that seen with Tetrahymena. Both isolated dyneins translocate taxol-stabilized, bovine brain microtubules in vitro. Under standard conditions, 22S dynein, like comparable dyneins from other organisms, translocates at velocities that are about three times faster than 14S dynein.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 9 (1988), S. 73-84 
    ISSN: 0886-1544
    Keywords: cilia ; metachronal waves ; electron microscopy ; calcium ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Structural and behavioral features of intact and permeabilized Paramecium tetraurelia have been defined as a basis for study of Ca2+ control of ciliary reversal. Motion analysis of living paramecia shows that all the cells in a population swim forward with gently curving spirals at speeds averaging 369 ± 19 μm/second. Ciliary reversal occurs in 10% of the cell population per second. Living paramecia, quick-fixed for scanning electron microscopy (SEM), show metachronal waves and an effective stroke obliquely toward the posterior end of the cell. Upon treatment with Triton X-100, swimming ceases and both scanning and transmission electron microscopy reveal cilia that uniformly project perpendicularly from the cell surface. Thin sections of these cells indicate that the ciliary, cell, and outer alveolar membranes are greatly disrupted or entirely missing and that the cytoplasm is also disrupted. These permeabilized paramecia can be reactivated and are capable of motility and regulation of motility. Motion analysis of cells reactivated with Mg2+ and ATP in low Ca2+ buffer (pCa7) shows that 71% swim forward in straight or curved paths at speeds averaging 221 ± 20 μm/second. When these cells are quick-fixed for SEM the metachronal wave patterns of living, forward swimming cells reappear. Motion analysis of permeabilized cells reactivated in high Ca2+ buffers (pCa 5.5) shows that 94% swim backward in tight spirals at a velocity averaging 156 ± 7 μm/second. SEM reveals a metachronal wave pattern with an effective stroke toward the anterior region. Although the permeabilized cells do not reverse spontaneously, the pCa response is preserved and the Ca2+ switch remains intact. The ciliary axonemes are largely exposed to the external environment. Therefore, the behavioral responses of these permeabilized cells depend on interaction of Ca2+ with molecules that remain bound to the axonemes throughout the extraction and reactivation procedures.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 12 (1989), S. 1-11 
    ISSN: 0886-1544
    Keywords: ciliary motility ; cAMP ; Ca2+ ; phosphoproteins ; signal transduction ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This study seeks to identity phosphoproteins in axonemes from Paramecium letraurelia whose phosphorylation responses to adenosine 3′,5′-cyclic monophosphate (cAMP) and Ca2+ parallel responses induced by these agents in ciliary behavior in this cell. In purified rxonemes, over 15 bands ranging from Mr 〉300 kDa to 19 kDa on SDS-PAGE incorporate 32P from adenosine 5′-γ-[32P]tri-phosphate (γ-32P-ATP) at pCa 7 in the absence of cAMP. A major band whose label turns over rapidly was identified at Mr 43 kDa. In the presence of 5 μM cAMP, more than eight bands, but not the Mr 43 kDa band, were labeled additionally or enhanced their labeling. These phosphoproteins and their kinases are structural components of the axoneme. Overall, some of the same major bands are labeled in the presence of cAMP in Triton X-100-permeabilized paramecia that retain their behavioral responses and in axonemes mechanically isolated from these cells. In particular, two major bands have been identified whose phosphorylation is greatly enhanced by cAMP at low concentrations: (1) a 29 kDa polypeptide whose cAMP-dependent phosphorylation is diminished at pCa 4 compared with pCa 7 and (2) a 65 kDa polypeptide whose phosphorylation is pCa insensitive. These polypeptides meet minimal criteria for signal-sensitive regulators of motility parameters in the Paramecium axoneme.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 27 (1994), S. 299-312 
    ISSN: 0886-1544
    Keywords: microtubule motors ; dynein ; cilia ; axoneme ; computer modeling ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This study considers the relationship between two structural forms of the 22S dynein arm of Tetrahymena thermophila: the bouquet and the compact arm. The compact arm differs from the bouquet and from other proposed forms (e.g., the “toadstool”) in that the globular domains are situated transversely across the interdoublet gap with one globular subunit, the head, proximal to the adjacent doublet microtubule. The other models place all three globular domains proximal to the neighboring doublet microtubule. When sliding of an isolated axoneme is induced, at least 57% of total attached arms on exposed doublets are in the compact form within dimensions of 24 × 24 × 12 nm, and only about 2% of the arms are bouquets. Toadstools are incompatible with the images seen. Bouquets are not found in regions of the doublet protected by a neighboring doublet. When axonemes with exposed doublets are treated with 0.5 M KCl for 30 min, the compct arms and the dynein heavy (H)-chains disappear, while isolated bouquets and dynein H-chains appear in the medium, suggesting that the compact arms give rise to the bouquets as they are solubilized. The bouquet is the predominant form of isolated 22S dynein molecules, which are found in two apparently enantiomorphic forms, within dimensions 45 × 39 × 13 nm; bouquets attached to doublets have dimensions similar to those of isolated bouquets. Computer modeling indicates that in an intact standard-diameter axoneme, these dimensions are incompatible with the interdoublet volume available for an arm; the bouquet therefore represents an unfolded compact arm. A plausible sequence of changes can be modeled to illustrate the conversion of an attached compact arm to an attached and then free bouquet. The toadstool is probably an artifact that arises after unfolding. Consistent with the conformational difference, H-chains of attached compact arms differ from those of isolated bouquets in their susceptibility to limited proteolysis. These results suggest that the compact arm, rather than the unfolded bouquet or the toadstool, is the functional form of the outer arm in the intact axoneme. © 1994 Wiley-Liss, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 32 (1995), S. 121-124 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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