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  • 1
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    Assessment ofg-dependent Cellular Gravitaxis: Determination of Cell Orientation from Locomotion Track (1997)
    Elsevier
    Details
    Publikationsdatum: 1997-03-01
    Print ISSN: 0022-5193
    Digitale ISSN: 1095-8541
    Thema: Biologie
    Publiziert von Elsevier
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
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    CECILIA, a versatile research tool for cellular responses to gravity (2002)
    Springer
    Details
    Publikationsdatum: 2002-09-01
    Print ISSN: 0938-0108
    Digitale ISSN: 1875-0494
    Thema: Maschinenbau , Allgemeine Naturwissenschaft , Technik allgemein
    Publiziert von Springer
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
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    The Gravikinetic Response of Paramecium is Based on Orientation-Dependent Mechanotransduction (1999)
    Springer
    Details
    Publikationsdatum: 1999-07-07
    Print ISSN: 0028-1042
    Digitale ISSN: 1432-1904
    Thema: Biologie , Chemie und Pharmazie , Allgemeine Naturwissenschaft
    Publiziert von Springer
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  • 4
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    Are receptor-activated ciliary motor responses mediated through voltage or current? (1978)
    Springer Nature
    Details
    Publikationsdatum: 1978-11-01
    Print ISSN: 0028-0836
    Digitale ISSN: 1476-4687
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Publiziert von Springer Nature
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Frequency and directional responses of cilia to membrane potential changes inParamecium (1974)
    Springer
    Journal of comparative physiology 92 (1974), S. 293-316 
    Details
    ISSN: 1432-1351
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Ciliary motor reactions and membrane responses to injected current stimulation inParamecium caudatum were recorded with a combined electrophysiological and high-speed cine system to investigate relations between ciliary activity and membrane potential. The power stroke of the cilia normally directed to the right rear rotates clockwise to a more posterior orientation in response to hyperpolarizing stimulation. Depolarization induces a counterclockwise shift, usually leading to the rapid reversal of beat direction toward the anterior end (Fig. 15). Ciliary frequency is increased either with hyperpolarization or with moderate or strong depolarization of the cell membrane. The frequency response is linked to the directional response in such a way that minimal frequency occurs during transition from reversed to normal beating, and that with increasing clock-wise or counterclockwise angular deviation of the power stroke from this sector of transition the frequency of beat is increased. In the course of transition from the reversed to normal beating the cilia are inactivated, i.e. they stick out perpendicularly to the cell surface without a polarized beat. A depression in normal beating activity somewhat resembling inactivation occurs with small depolarizations. Hyperpolarization-induced frequency time courses are significantly slower than those evoked by membrane depolarization. The role of transmembrane calcium fluxes and consequent modification of intraciliary calcium concentrations is considered with regard to the observed ciliary responses.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00696617
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Ciliary beating in three dimensions: Steps of a quantitative description (1992)
    Springer
    Journal of mathematical biology 30 (1992), S. 215-249 
    Details
    ISSN: 1432-1416
    Schlagwort(e): Ciliary activity ; Voltage-clamp ; 3D-t video-processing
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract We document a novel approach for quantitative assessment of ciliary activity, exemplified in rapid three-dimensional cyclic motion of the frontal cirri of Stylonychia. Cells held under voltage-clamp control are stimulated by step pulses to elicit reproducible hyperpolarization- or depolarization-induced ciliary motor responses. High-speed video recording at 200 fields per second is used for imaging ciliary organelles of the same cell in two perspectives: the axial view and, following cell rotation by 90°, the lateral view. From video sequences of typically 1 s, the contours of the cirral images are determined and digitized. Computer programs are established to (1) reduce an observed image to a “ciliary axis”, (2) sort series of axes by template to generate an averaged ciliary cycle in 2D-projection, and (3) to associate the generalized axial and lateral 2D-images for generation of a sequence of three-dimensional images, which quantitatively represent the cycle in space and time. The method allows us to produce pre-determined perspectives of images selected from the ciliary cycle, and to generate stereo views for graphical representation of ciliary motion. The approach includes a potential for extraction of the complete microtubular sliding program of a cilium under reproducible electric stimulation of the ciliary membrane.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00176150
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    Regulation der Cilienmetachronie bei der “Fluchtreaktion” von Paramecium (1969)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 16 (1969), S. 0 
    Details
    ISSN: 1550-7408
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: SYNOPSIS. Paramecia induced to perform high rates of avoiding reactions by mechanical stimulation and the action of Ba ions were instantaneously fixed with OsO4. Quantitative evaluation of the preparations revealed, among other things, metachronal stages of the transition between the ciliary patterns of swimming backward and forward. In each of the transitory stages, metachronal waves of swimming forward were found at the anterior end and waves of swimming backward at the posterior end of the animal. This confirms the so-called Párducz-scheme of avoiding reaction for the case of homogeneous chemical stimulation as well as for mechanical stimulation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1550-7408.1969.tb02340.x
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Cellular Behaviour Modulated by Ions: Electrophysiological Implications (1989)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 36 (1989), S. 0 
    Details
    ISSN: 1550-7408
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: . This essay considers the responses of Paramecium and other ciliates to the inorganic ion environment from an elec-trophysiological point of view. In reviewing data from published and unpublished sources it is shown that ions affect the cellular behaviour in multiple ways because the transmembrane potential can change due to the alteration of equilibrium potentials, ion conductances and surface charges of the membrane. Sensory input including effects from the ionic environment converge upon the membrane potential which has a temporal and spatial summing function. Hyperpolarizing and depolarizing potential shifts from the set point are near-simultaneously and omnidirectionally transmitted along the membrane including the ciliary boundaries. The membrane potential regulates ciliary motility via an intraciliary messenger, Ca2+, which can enter, and presumably leave, the cytosol directly adjacent to the ciliary motor. Integration of the responses of thousands of cilia occurs in accordance with the electrical and structural provisions of the cell. Potential-regulated motor and behavioural responses attenuate with time. This phenomenon, which has been loosely termed adaptation, has an electrophysiological basis in analogy to membrane accommodation following sustained stimulus input. The mechanisms of adaptation serve to restore, in principle, the membrane resting state and, thereby, the sensitivity to depolarizing and hyperpolarizing shifts of the membrane potential and the cell's responsiveness to environmental stimuli, respectively. For the inorganic ions involved in chemosensation the terms attractant and repellent are not applicable. They should be reserved to signalling substances which per se can define the behaviour of the cell.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1550-7408.1989.tb01082.x
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  • 9
    Digitale Medien
    Digitale Medien
    Graviresponses of Gliding and Swimming Loxodes Using Step Transition to Weightlessness (1998)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 45 (1998), S. 0 
    Details
    ISSN: 1550-7408
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: Cells of Loxodes striatus were adjusted to defined culturing, experimental solution, O2-supply, temperature, and state of equilibration to be subjected to step-type transition of acceleration from normal gravity (1 g) to the weightless condition (μg) during free fall in a 500-m drop shaft. Cellular locomotion inside a vertical experimental chamber was recorded preceding transition and during 10 s of μg. Cell tracks from video records were used to separate cells gliding along a solid surface from free swimmers, and to determine gravitaxis and gravikinesis of gliding and swimming cells. With O2 concentrations ≥ 40% air saturation, gliders and swimmers showed a positive gravitaxis. In μg gravitaxis of gliders relaxed within 5 s, whereas gravitaxis relaxation of swimmers was not completed even after 10 s. Rates of horizontal gliders (319 μm/s) exceeded those of horizontal swimmers (275 μm/s). Relaxation of gravikinesis was incomplete after 10 s of μg. Analysis of the locomotion rates during the g-step transition revealed that gliders sediment more slowly than swimmers (14 versus 45 μm/s). The gravikinesis of gliders cancelled sedimentation effects during upward and downward locomotion tending to maintain cells at a predetermined level inside sediments of a freshwater habitat. At ≥ 40% air saturation, gravikinesis of swimmers augmented the speed of the majority of cells during gravitaxis, which favours fast vertical migrations of Loxodes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1550-7408.1998.tb05092.x
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  • 10
    Digitale Medien
    Digitale Medien
    Mechanoreception and signal transmission in the lateral ciliated cells on the gill ofMytilus (1982)
    Springer
    Journal of comparative physiology 145 (1982), S. 351-362 
    Details
    ISSN: 1432-1351
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary 1. The lateral ciliated cells of the gill epithelium ofMytilus edulis were mechanically stimulated with a fine-tipped glass stylus. The electrical responses were recorded intracellularly from the ciliated cells, and the ciliary responses were photographed. 2. Mechanical stimuli to the cilia and to the cell surface evoked a depolarizing membrane response (receptor potential) which increased with the rate of rise and the steady-state amplitude of the electric pulse driving the piezo-transducer. The effective parameter of the stimulus was the velocity of the stylus. 3. Stimulation of the cilia in various directions (four parallel and one perpendicular to the cell surface), including direct stimulation of the lateral cell, led to similar depolarizing receptor potentials. The ‘perpendicular’ stimulation was among the most effective. 4. The same electric responses were elicited from stimuli applied to any of the four rows of lateral ciliated cells. 5. The mechanically elicited depolarizing receptor potentials triggered action potentials. Such regenerative depolarizations were often missing in the isolated filament preparation, presumably due to subthreshold receptor potentials. 6. The electric membrane responses and arrest responses of the cilia following membrane depolarization were propagated with decrement along several cells. The area of the ciliary arrest responses increased with stimulus intensity extending to a maximum of 70 μm in any direction. 7. Exposure to Ca-free artificial sea water suppressed both the depolarizing receptor potential and the ciliary arrest response. Action potentials with long-lasting plateaus occurred spontaneously in the Ca-free solution. 8. Total substitution of Na with choline in artificial sea water hyperpolarized the membrane, but did not interfere with the generation of receptor potentials. Spontaneous and mechanically induced action potentials were suppressed in this solution. Electrical responses were not transmitted to the neighbouring cells, and no ciliary arrest responses were seen in the absence of external Na. 9. We conclude that mechanical stimuli impinging on the lateral cells via the cilia generate a Ca-dependent depolarizing receptor potential which elicits a Na-dependent regenerative process. The graded depolarization spreads transcellularly with decrement, and regulates the local arrest response of the cilia, which may play a role in the feeding behaviour of the mussel.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00619339
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