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  • 1990-1994  (3)
  • 1985-1989  (1)
  • Life and Medical Sciences  (4)
  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 6 (1986), S. 256-272 
    ISSN: 0886-1544
    Keywords: ciliary motility ; cAMP regulation ; swimming speed ; membrane potential ; detergent models ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The membrane potential of Paramecium controls the frequency and direction of the ciliary beat, thus determining the cell's swimming behavior. Stimuli that hyperpolarize the membrane potential increase the ciliary beat frequency and therefore increase forward swimming speed. We have observed that (1) drugs that elevate intracellular cyclic AMP increased swimming speed 2-3-fold, (2) hyperpolarizing the membrane potential by manipulation of extracellular cations (e.g., K+) induced both a transient increase in, and a higher sustained level of cyclic AMP compared to the control, and (3) the swimming speed of detergent-permeabilized cells in MgATP was stimulated 2-fold by the addition of cyclic AMP. Our results suggest that the membrane potential can regulate intracellular cAMP in Paramecium and that control of swimming speed by membrane potential may in part be mediated by cAMP.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 24 (1993), S. 17-28 
    ISSN: 0886-1544
    Keywords: antibody ; motility ; axoneme ; ATPase ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Three forms of dynein (22S, 19S, and 12S) were purified from Paramecium cilia. Two classes of monoclonal antibodies against purified 22S dynein were generated. One class reacted on immunoblots with the heavy chains of 22S, 19S, and 12S dyneins; the second class reacted with an 88 kD intermediate chain of 22S dynein. Polyclonal antiserum to the heavy chains of 22S dynein reacted with the γ-heavy chain of 22S and 19S dyneins. A previously described antiserum raised against 22S dynein [Travis et al.: Biochim. Biophys. Acta 966:73-83, 1988] recognized the γ-heavy chain of 22S dynein which was also present in 19S and 12S dyneins, along with the 88 and 76 kD intermediate chains of 22S dynein. This antiserum was also able to immunoprecipitate dynein from crude extracts of cilia.Electron microscopy revealed that the 22S dynein consisted mainly of two-headed particles with some three-headed particles present. The 12S dynein was mainly one-headed particles. The 19S dynein was a mixture of three-, two-, and one-headed particles. The immunological and electron microscopic studies showed that 19S dynein arises from 22S dynein, and that 12S dynein is heterogeneous, composed of the γ-heavy chain of 22S dynein and a unique dynein ATPase.The polyclonal antibodies were also used to detect cross-reactive proteins in other organisms. Both the anti-heavy chain and the anti-22S dynein sera reacted strongly with 22S outer arm dynein of Tetrahymena, but not with the 14S dynein of this organism. © 1993 Wiley-Liss, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 27 (1994), S. 101-107 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 19 (1991), S. 91-98 
    ISSN: 0886-1544
    Keywords: motion analysis ; motility ; adaptation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Paramecium letraurelia is a ciliated protist that alters its swimming behavior in response to various stimuli. Like the sensory responses of many organisms, these responses in Paramecium show adaptation to continued stimulation. For quantitative studies of the initial response to stimulation. and of the time course of adaptation, we have developed a computerized motion analysis assay that can detect deviations from the normal swimming pattern in a population of cells. The motion of an average of ten cells was quantified during periods ranging from 15 to 60 seconds, with a time resolution of 1/15 seconds. During normal forward swimming, the maximum deviation from a straight-line path was less than 17°. Path deviations above this threshold value were defined as changes in swimming direction. The percentage of total path time that cells spent deviating from forward swimming was defined as percent directional changes (PDC). This parameter was used to construct dose-response curves for the behavioral effects of various externally added cations known to induce behavioral changes and also to show the time course of adaptation to a depolarizing K+ stimulus. This assay is a valuable tool for studies of chemoeffectors or mutations that alter the swimming behavior of Paramecium and may also be applicable to other motile organisms.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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