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Cole E, Gaertig J. Anterior-posterior pattern formation in ciliates. J Eukaryot Microbiol 2022; 69:e12890. [PMID: 35075744 PMCID: PMC9309198 DOI: 10.1111/jeu.12890] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Revised: 01/06/2022] [Accepted: 01/17/2022] [Indexed: 11/29/2022]
Abstract
As single cells, ciliates build, duplicate, and even regenerate complex cortical patterns by largely unknown mechanisms that precisely position organelles along two cell‐wide axes: anterior–posterior and circumferential (left–right). We review our current understanding of intracellular patterning along the anterior–posterior axis in ciliates, with emphasis on how the new pattern emerges during cell division. We focus on the recent progress at the molecular level that has been driven by the discovery of genes whose mutations cause organelle positioning defects in the model ciliate Tetrahymena thermophila. These investigations have revealed a network of highly conserved kinases that are confined to either anterior or posterior domains in the cell cortex. These pattern‐regulating kinases create zones of cortical inhibition that by exclusion determine the precise placement of organelles. We discuss observations and models derived from classical microsurgical experiments in large ciliates (including Stentor) and interpret them in light of recent molecular findings in Tetrahymena. In particular, we address the involvement of intracellular gradients as vehicles for positioning organelles along the anterior‐posterior axis.
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Affiliation(s)
- Eric Cole
- Biology Department, St. Olaf College, Northfield, MN, USA
| | - Jacek Gaertig
- Department of Cellular Biology, University of Georgia, Athens, GA, USA
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2
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Abstract
Electrical properties of E. vannus were investigated by use of constant current injection, voltage-clamp, and isoosmotic ion substitution. The resting potential of approximately -40 mV was K(+) and Ca(2+)-dependent. Spontaneous depolarizations occurred frequently with peaks around -20 mV and durations from several hundred ms to several s. External Ba(2+) or internal Cs(+) induced all-or-none action potentials. Current stimuli induced Ca(2+)-dependent graded action potentials. Sr(2+) or Ba(2+), but not Mg(2+), instead of Ca(2+) increased the regenerative response. Repolarization occurred in two steps: a first fast and a second slow one. It was strongly modified by the Ca(2+) substitutes. A voltage-dependent small Ca(2+) inward current was activated at depolarizations beyond -20 mV. It triggered a fast and a slowly activating K(+) outward current and was itself short-circuited by the fast K(+) current. Therefore, it could only be measured when K(+) currents were not activated or inhibited. A slowly activating Na(+) inward current was identified that turned to outward direction after replacement of external Na(+) by choline(+). The K(+) outward currents differed in their sensitivity to external TEA(+) and in their inactivation kinetics. All currents were correlated to the voltage-dependent influx of Ca(2+).
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Krause M, Bräucker R, Hemmersbach R. Gravikinesis in Stylonychia mytilus is based on membrane potential changes. J Exp Biol 2010; 213:161-71. [DOI: 10.1242/jeb.030940] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARY
The graviperception of the hypotrichous ciliate Stylonychia mytilus was investigated using electrophysiological methods and behavioural analysis. It is shown that Stylonychia can sense gravity and thereby compensates sedimentation rate by a negative gravikinesis. The graviresponse consists of a velocity-regulating physiological component (negative gravikinesis) and an additional orientational component. The latter is largely based on a physical mechanism but might, in addition, be affected by the frequency of ciliary reversals, which is under physiological control. We show that the external stimulus of gravity is transformed to a physiological signal, activating mechanosensitive calcium and potassium channels. Earlier electrophysiological experiments revealed that these ion channels are distributed in the manner of two opposing gradients over the surface membrane. Here, we show, for the first time, records of gravireceptor potentials in Stylonychia that are presumably based on this two-gradient system of ion channels. The gravireceptor potentials had maximum amplitudes of approximately 4 mV and slow activation characteristics (0.03 mV s–1). The presumptive number of involved graviperceptive ion channels was calculated and correlates with the analysis of the locomotive behaviour.
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Affiliation(s)
- Martin Krause
- Department of General Zoology and Neurobiology, Ruhr-University Bochum, D-44780 Bochum, Germany
| | | | - Ruth Hemmersbach
- DLR, Institute of Aerospace Medicine, Linder Höhe, D-51174 Köln, Germany
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Abstract
Studies of ion channels have for long been dominated by the animalcentric, if not anthropocentric, view of physiology. The structures and activities of ion channels had, however, evolved long before the appearance of complex multicellular organisms on earth. The diversity of ion channels existing in cellular membranes of prokaryotes is a good example. Although at first it may appear as a paradox that most of what we know about the structure of eukaryotic ion channels is based on the structure of bacterial channels, this should not be surprising given the evolutionary relatedness of all living organisms and suitability of microbial cells for structural studies of biological macromolecules in a laboratory environment. Genome sequences of the human as well as various microbial, plant, and animal organisms unambiguously established the evolutionary links, whereas crystallographic studies of the structures of major types of ion channels published over the last decade clearly demonstrated the advantage of using microbes as experimental organisms. The purpose of this review is not only to provide an account of acquired knowledge on microbial ion channels but also to show that the study of microbes and their ion channels may also hold a key to solving unresolved molecular mysteries in the future.
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Affiliation(s)
- Boris Martinac
- School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland, Australia.
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De Peyer JE, Machemer H. Electromechanical coupling in cilia I. Effects of depolarizing voltage steps. ACTA ACUST UNITED AC 2005. [DOI: 10.1002/cm.970020507] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Electromechanical coupling in cilia II. Effects of hyperpolarizing voltage steps. ACTA ACUST UNITED AC 2005. [DOI: 10.1002/cm.970020508] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Mori G, Erra F, Cionini K, Banchetti R. Sublethal doses of heavy metals and Slow‐Down pattern ofEuplotes crassus(Ciliophora, Hypotrichia): A behavioural bioassay. ACTA ACUST UNITED AC 2003. [DOI: 10.1080/11250000309356492] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Hemmersbach R, Becker E, Stockem W. Influence of extremely low frequency electromagnetic fields on the swimming behavior of ciliates. Bioelectromagnetics 2000; 18:491-8. [PMID: 9338630 DOI: 10.1002/(sici)1521-186x(1997)18:7<491::aid-bem4>3.0.co;2-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Different species of ciliates (Paramecium biaurelia, Loxodes striatus, Tetrahymena thermophila) have been taken as model systems to study the effects of extremely low-frequency electromagnetic fields (50 Hz, 0.5-2.0 mT) on the cellular level. A dose-dependent increase in the mean swimming velocity and a decrease in the linearity of cell tracks were observed in all wild-type cells. In contrast, field-exposure did not increase the number of directional turns of the Paramecium tetraurelia pawn mutant (d4-500r), which is characterized by defective Ca2+-channels. The described changes indicate a direct effect of low frequency electromagnetic fields on the transport mechanisms of the cell membrane for ions controlling the motile activity of cilia.
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Affiliation(s)
- R Hemmersbach
- Institute of Aerospace Medicine, DLR (German Aerospace Research Establishment), Köln.
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Rhythmic spontaneous depolarizations determine a slow-and-fast rhythm in walking of the marine hypotrich Euplotes vannus. Eur J Protistol 1996. [DOI: 10.1016/s0932-4739(96)80038-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Johansson S, Sundgren AK, Klimenko V. Graded action potentials generated by neurons in rat hypothalamic slices. Brain Res 1995; 700:240-4. [PMID: 8624716 DOI: 10.1016/0006-8993(95)00969-w] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Preoptic neurons in rat hypothalamic slices were investigated with tight-seal whole-cell recording techniques. The main aim was to investigate the ability to generate graded, stimulus-dependent impulses. In response to rectangular current pulses, all cells generated impulses with an amplitude that to some degree depended on the stimulus strength. Stronger current steps induced impulses of larger amplitude. In 50% of the cells, a systematic variation of impulse amplitude of more than 10 mV (up to 40 mV) was recorded, implying a clear deviation from the 'all-or-nothing' principle. A clear variation in amplitude of spontaneous impulses was also recorded, in the whole-cell mode as well as from intact cells in the cell-attached mode.
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Affiliation(s)
- S Johansson
- Department of Neurochemistry and Neurotoxicology, Stockholm University, Sweden
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Johansson S. Graded action potentials generated by differentiated human neuroblastoma cells. ACTA PHYSIOLOGICA SCANDINAVICA 1994; 151:331-41. [PMID: 7976405 DOI: 10.1111/j.1748-1716.1994.tb09752.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Stimulus-dependent impulses and resting membrane parameters of human SH-SY5Y neuroblastoma cells, induced to differentiate by retinoic acid, were investigated with tight-seal recording techniques. Mean resting potential was -53 mV, mean input resistance 2.1 G omega, mean capacitance 14 pF, and mean time constant 30 ms. Rectangular current steps induced clearly stimulus-dependent impulses, with stronger current steps causing impulses of larger amplitude. The degree of impulse variability differed significantly among different cells. The current thresholds for impulse generation ranged from 35 to 100 pA for 10 ms current steps. With longer current steps, thresholds below 10 pA were recorded. In response to 0.5-1 s long current steps, most cells generated only a single impulse, but a few cells generated two impulses. When two impulses were generated, the interval between the impulses decreased with increasing stimulus strength. Whole-cell currents were recorded under voltage-clamp conditions. Voltage-activated, tetrodotoxin-sensitive Na+ currents and 'delayed rectifier' K+ currents were recorded. The degree of impulse variability was correlated to the maximum Na+ current density. Cells with large Na+ currents showed little impulse variability, while a marked variability was recorded in cells with intermediate or small Na+ currents. Cells which generated more than one impulse in response to prolonged stimuli belonged to the group with large Na+ currents. Spontaneous impulse-currents were recorded from cell-attached membrane patches on intact cells. Also these impulses showed a large variability in amplitude: In each of five cells analysed, the peak-to-peak amplitude varied by a factor larger than 1.7.
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Affiliation(s)
- S Johansson
- Department of Neurochemistry and Neurotoxicology, Stockholm University, Sweden
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BERG TRONDOLAV, SAND OLAV. Spontaneous All-or-Nothing Action Potentials in the Ciliate Bursaridium difficile. J Eukaryot Microbiol 1994. [DOI: 10.1111/j.1550-7408.1994.tb05928.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Mogami Y, Pernberg J, Machemer H. Ciliary beating in three dimensions: steps of a quantitative description. J Math Biol 1992; 30:215-49. [PMID: 1735787 DOI: 10.1007/bf00176150] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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 degrees, 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 predetermined 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.
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Affiliation(s)
- Y Mogami
- Arbeitsgruppe Zelluläre Erregungsphysiologie, Fakultät für Biologie, Ruhr-Universität, Bochum, Federal Republic of Germany
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Tentacle regulating potentials inNoctiluca miliaris: their generation sites and ionic mechanisms. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 1988. [DOI: 10.1007/bf00606083] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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17
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Loss of electrical excitability during encystment of the hypotrichous ciliate Stylonychia mytilus. Naturwissenschaften 1987. [DOI: 10.1007/bf00366527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Moss AG, Tamm SL. Electrophysiological control of ciliary motor responses in the ctenophore Pleurobrachia. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 1986; 158:311-30. [PMID: 2873243 DOI: 10.1007/bf00603615] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Prey capture by a tentacle of the ctenophore Pleurobrachia elicits a reversal of beat direction and increase in beat frequency of comb plates in rows adjacent to the catching tentacle (Tamm and Moss 1985). These ciliary motor responses were elicited in intact animals by repetitive electrical stimulation of a tentacle or the midsubtentacular body surface with a suction electrode. An isolated split-comb row preparation allowed stable intracellular recording from comb plate cells during electrically stimulated motor responses of the comb plates, which were imaged by high-speed video microscopy. During normal beating in the absence of electrical stimulation, comb plate cells showed no changes in the resting membrane potential, which was typically about -60 mV. Trains of electrical impulses (5/s, 5 ms duration, at 5-15 V) delivered by an extracellular suction electrode elicited summing facilitating synaptic potentials which gave rise to graded regenerative responses. High K+ artificial seawater caused progressive depolarization of the polster cells which led to volleys of action potentials. Current injection (depolarizing or release from hyperpolarizing current) also elicited regenerative responses; the rate of rise and the peak amplitude were graded with intensity of stimulus current beyond a threshold value of about -40 mV. Increasing levels of subthreshold depolarization were correlated with increasing rates of beating in the normal direction. Action potentials were accompanied by laydown (upward curvature of nonbeating plates), reversed beating at high frequency, and intermediate beat patterns. TEA increased the summed depolarization elicited by pulse train stimulation, as well as the size and duration of the action potentials. TEA-enhanced single action potentials evoked a sudden arrest, laydown and brief bout of reversed beating. Dual electrode impalements showed that cells in the same comb plate ridge experienced similar but not identical electrical activity, even though all of their cilia beat synchronously. The large number of cells making up a comb plate, their highly asymmetric shape, and their complex innervation and electrical characteristics present interesting features of bioelectric control not found in other cilia.
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Changes in voltage-dependent calcium currents during the cell cycle of the ciliate Stylonychia. Exp Cell Res 1986; 162:549-54. [PMID: 2417873 DOI: 10.1016/0014-4827(86)90359-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Electrophysiological properties of the hypotrichous ciliate Stylonychia mytilus were studied at two stages of its cell cycle: within 30 min after cell division and several hours thereafter. The action potential wave form, and the relative amount of two voltage-dependent calcium inward currents are significantly different in 'young' daughter cells as compared with 'adult' cells. The ratio between total inward and outward current is also larger in 'young' cells. The results provide evidence that during its cell cycle Stylonychia undergoes qualitative developmental changes with respect to its ionic channels in the membrane. These changes may explain the different cell behaviour observed up to 1 h after cell division.
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Abstract
Incubation of the hypotrichous ciliate Stylonychia mytilus in fluorescein-labeled concanavalin A (Con A, 0.1-0.5 microgram/ml) produced a strong fluorescence of its membranelles, but comparatively weak fluorescence of the other compound cilia and of the somatic membrane. Compared to untreated cells, the frequency of spontaneous backward movements was reduced in the presence of 0.5 microgram/ml ConA. In electrophysiological experiments Con A altered the excitability of the cell membrane. The two-peak action potential lost its second component which is associated with voltage-dependent Ca channels in the membranelles. The corresponding Ca current (Ca current I) was inhibited by low concentrations of Con A (0.2-0.5 microgram/ml). A second voltage-dependent Ca current (Ca current II) was not affected. Reducing the K outward current by intracellular Cs and/or extracellular tetraethylammonium, or changing the holding potential, did not restore the Con A-sensitive Ca current I. Con A also inhibited this current when Ca was replaced by Ba. The inhibitory effect of Con A on the voltage-dependent Ca current I was prevented by 10-30 mM alpha-methyl-D-mannoside, and the lectin wheat germ agglutinin (20 micrograms/ml) did not affect the Ca currents, indicating that the Con A effect was mediated by binding to specific sugar residues on the excitable membrane. The succinylated dimeric derivative of Con A did not inhibit Ca current I up to concentrations of 5 micrograms/ml. It is concluded that the two voltage-dependent Ca currents in Stylonychia can be chemically isolated due to their different sensitivity to Con A, which appears to bind preferentially to sites near or at the Ca channel in the membranellar membrane.
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Pape HC, Machemer H. Electrical properties and membrane currents in the ciliateDidinium. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 1986. [DOI: 10.1007/bf00614525] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Ballanyi K, Deitmer JW. Concentration-dependent effects of Ba2+ on action potential and membrane currents in the ciliate Stylonychia. ACTA ACUST UNITED AC 1984. [DOI: 10.1016/0300-9629(84)90599-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Motor control in three types of ciliary organelles in the ciliateStylonychia. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 1984. [DOI: 10.1007/bf00605396] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Machemer-R�hnisch S, Machemer H. Receptor current following controlled stimulation of immobile tail cilia inParamecium caudatum. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 1984. [DOI: 10.1007/bf00604992] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Threshold activation and dynamic response range of cilia following low rates of membrane polarization under voltage-clamp. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 1983. [DOI: 10.1007/bf00606372] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Wood DC. Membrane permeabilities determining resting, action and mechanoreceptor potentials inStentor coeruleus. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 1982. [DOI: 10.1007/bf00609450] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Machemer H, de Peyer JE. Analysis of ciliary beating frequency under voltage clamp control of the membrane. PROGRESS IN CLINICAL AND BIOLOGICAL RESEARCH 1982; 80:205-10. [PMID: 6808519 DOI: 10.1002/cm.970020739] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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Deitmer JW. Voltage and time characteristics of the potassium mechanoreceptor current in the ciliateStylonychia. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 1981. [DOI: 10.1007/bf01342664] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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de Peyer J, Machemer H. Are receptor-activated ciliary motor responses mediated through voltage or current? Nature 1978; 276:285-7. [PMID: 101892 DOI: 10.1038/276285a0] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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de Peyer JE, Machemer H. Hyperpolarizing and depolarizing mechanoreceptor potentials inStylonychia. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 1978. [DOI: 10.1007/bf01350116] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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