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  • 1
    Electronic Resource
    Electronic Resource
    Control of cytoplasmic streaming by extracellular Ca2+ in permeabilizedNitella cells (1983)
    Springer
    Protoplasma 116 (1983), S. 75-77 
    Details
    ISSN: 1615-6102
    Keywords: Ca2+ ; Cell model ; Cytoplasmic streaming ; Nitella
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Cytoplasmic streaming in permeabilizedNitella cells was found to be controlled by Ca2+ of physiological concentration. The streaming driven by Mg · ATP was scarcely affected by 10−7 M Ca2+, but was inhibited significantly by 5 × 10−7 M Ca2+ and completely by 10−6 M Ca2+. The inhibition by Ca2+ was completely reversible even at 10−5 M.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01294233
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Reversible inhibition of cytoplasmic streaming by intracellular Ca2+ in tonoplast-free cells ofChara australis (1981)
    Springer
    Protoplasma 109 (1981), S. 103-111 
    Details
    ISSN: 1615-6102
    Keywords: Calcium ions ; Chara ; Cytoplasmic streaming ; Internal perfusion ; Tonoplast-free cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The effect of the intracellular concentration of Ca2+ on the cytoplasmic streaming of tonoplast-free cells ofChara australis was studied by intracellular perfusion. The perfusion media contained 1 mM Mg · ATP. Both cell ends were cut and left open. Media of different Ca2+ concentrations were perfused through the cell and the rate of the cytoplasmic streaming just after perfusion was measured. The critical concentration of Ca2+ for inhibiting the streaming was 5 × 10−4M, which was substantially higher than that found earlier byWilliamson (1975) andHayama et al. (1979). Recovery from the inhibition occurred, though not completely, by removing Ca2+. In tonoplast-free cells the Ca2+ sensitivity differed according to the culture conditions. Cells cultured indoors exhibited a higher sensitivity than those cultured outdoors. Theformer cells contained granule-rich endoplasm aggregates after loss of the tonoplast, while the latter cells did no such aggregates. The aggregates were fixed to the cortical gel with a high dosage of Ca2+ and freed by removing it.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01287633
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Motive force and rate of cytoplasmic streaming inCharaceae cells in relation to osmotic pressure and ionic strength of the vacuole and the cytoplasm (1981)
    Springer
    Protoplasma 109 (1981), S. 113-125 
    Details
    ISSN: 1615-6102
    Keywords: Actin filaments ; Chara ; Cytoplasmic streaming ; Internal osmotic pressure ; Nitella ; Tonoplast-free cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The effect of osmolarity of the vacuolar sap ofChara australis on cytoplasmic streaming was analyzed using the vacuolar perfusion technique. The osmolarity was varied between 0.3 M, which is normal and 1.2 M. The streaming rate decreased markedly with an increase in sap osmolarity, while the motive force increased significantly. This may be explained in terms of an increase in the sliding resistance at the sol-gel interface where active shearing occurs. Increase in the resistance is assumed to be caused by osmotic dehydration of the cytoplasm. This assumption was verified by the fact that in tonoplast-free cells, no significant inhibition of the streaming was observed by heightening the osmolarity of the cytoplasm with sorbitol. Heightening it with K+ salts inhibited the streaming to a greater extent than with sorbitol. The inhibition differed according to the anion species. Potassium methanesulfonate at 0.3 M and KCl at 0.6 M stopped the streaming almost completely, while 0.59 M K2SO4 was less inhibitory. Actin filaments were observed even in the presence of 0.6 M KCl.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01287634
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  • 4
    Electronic Resource
    Electronic Resource
    Phosphorylation-dephosphorylation is involved in Ca2+-controlled cytoplasmic streaming of characean cells (1987)
    Springer
    Protoplasma 136 (1987), S. 161-169 
    Details
    ISSN: 1615-6102
    Keywords: Characeae ; Ca2+ ; Cytoplasmic streaming ; Protein phosphatase ; Protein phosphatase inhibitor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The mechanism of Ca2+ regulation of the cytoplasmic streaming in characean cells was studied in relation to protein phosphorylation and dephosphorylation. A tonoplast-free cell model was developed which was sensitive to Ca2+. Protein phosphatase-1 and its inhibitor-1 were applied into the tonoplast-free cells. A synthetic inhibitor of protein phosphatase, α-naphthylphosphate, was applied either to tonoplast-free cells from inside or to the outside of plasmalemma-permeabilized cells which are known to be very sensitive to Ca2+. ATP-γ-S applied to permeabilized cells strongly inhibited the recovery of the streaming which had been stopped by 10 μ M Ca2+. Both inhibitor-l and α-naphthylphosphate inhibited the streaming even in the absence of Ca2+. On the other hand, protein phosphatase-l recovered the streaming even in the presence of Ca2+. The results indicate that characean streaming is regulated by the phosphorylation state of a regulatory and/or motile protein component. Streaming is activated when the component is dephosphorylated and inactivated when the component is phosphorylated. Ca2+ is assumed to stimulate both phosphorylation and dephosphorylation of the component. Involvement of Ca2+/calmodulin in the streaming recovery was discussed in terms of the stimulation of dephosphorylation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01276365
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  • 5
    Electronic Resource
    Electronic Resource
    Involvement of Ca2 + and flowing endoplasm in recovery of cytoplasmic streaming after K+-induced cessation (1984)
    Springer
    Protoplasma 121 (1984), S. 178-185 
    Details
    ISSN: 1615-6102
    Keywords: Action potential ; Ca2+ ; Chara ; Cytoplasmic streaming ; EGTA ; Nitella ; Permeabilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary When K+ of high concentration (50 mM) was applied toNitella cells, the cytoplasmic streaming stopped instantly as in the case of electrical stimulation. Recovery of the streaming after chemical stimulation was much slower than after electrical stimulation. When the endoplasm content was modified by centrifugation, streaming recovery was accelerated in the centrifugal cell fragments rich in endoplasm and deccelerated in those poor in it. The recovery was also accelerated either by permeabilizing the plasmalemma in the presence of EGTA in the external solution or by removing the tonoplast by vacuolar perfusion with the EGTA-containing medium. We concluded that the streaming was recovered due to decrease of the cytoplasmic Ca2+ concentration, which seems to be accelerated by sequestering of Ca2+ by endoplasmic components. The slow recovery of the streaming after KCl-stimulated cessation is assumed to be caused by continuous influx of Ca2 + during the prolonged membrane depolarization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01282311
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    Paper (German National Licenses)
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