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  • Kalanchoë (CO2 fixation, rhythm)  (2)
  • Life and Medical Sciences  (2)
  • Citrate transport  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Endogenous rhythms and chaos in crassulacean acid metabolism (1992)
    Springer
    Planta 188 (1992), S. 28-38 
    Details
    ISSN: 1432-2048
    Keywords: Beat oscillator ; Chaos ; Crassulacean acid metabolism ; Endogenous rhythm ; Kalanchoë (CO2 fixation, rhythm) ; Simulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Endogenous free-running regular circadian oscillations of net CO2 exchange in the crassulacean-acidmetabolism (CAM) plantKalanchoë daigremontiana Hamet et Perrier de la Bâthie under constant external conditions in continuous light have been shown to change to irregular non-predictable (chaotic) time behaviour as irradiance or temperature are raised above a critical level. A model of CAM has been constructed with pools of major metabolites of varying concentrations, flows of metabolites leading to exchange between pools, metabolite transformations determined by chemical reactions, and feedback regulations. The model is described by a system of coupled non-linear differential equations. It shows stable rhythmicity in normal dark-light cycles and in continuous light and, like theK. daigremontiana leaves in the experiments, a change to chaos as irradiance is increased. The maintenance of endogenous oscillations in the model is brought about by a hysteresis switch or beat oscillator between two stable oscillation modes. In CAM these stable modes are vacuolar malate accumulation and remobilization. The model shows that the physical nature of the beat oscillator in the leaves can be explained by the balance between active and passive transport at the tonoplast.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01160709
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Endogenous rhythms and chaos in crassulacean acid metabolism (1992)
    Springer
    Planta 188 (1992), S. 28-38 
    Details
    ISSN: 1432-2048
    Keywords: Beat oscillator ; Chaos ; Crassulacean acid metabolism ; Endogenous rhythm ; Kalanchoë (CO2 fixation, rhythm) ; Simulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Endogenous free-running regular circadian oscillations of net CO2 exchange in the crassulacean-acidmetabolism (CAM) plant Kalanchoë daigremontiana Hamet et Perrier de la Bâthie under constant external conditions in continuous light have been shown to change to irregular non-predictable (chaotic) time behaviour as irradiance or temperature are raised above a critical level. A model of CAM has been constructed with pools of major metabolites of varying concentrations, flows of metabolites leading to exchange between pools, metabolite transformations determined by chemical reactions, and feedback regulations. The model is described by a system of coupled non-linear differential equations. It shows stable rhythmicity in normal dark-light cycles and in continuous light and, like the K. daigremontiana leaves in the experiments, a change to chaos as irradiance is increased. The maintenance of endogenous oscillations in the model is brought about by a hysteresis switch or beat oscillator between two stable oscillation modes. In CAM these stable modes are vacuolar malate accumulation and remobilization. The model shows that the physical nature of the beat oscillator in the leaves can be explained by the balance between active and passive transport at the tonoplast.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00198936
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    The electrochemical proton gradient and its influence on citrate uptake in tonoplast vesicles of Hevea brasiliensis (1981)
    Springer
    Planta 153 (1981), S. 486-493 
    Details
    ISSN: 1432-2048
    Keywords: ATP ; Citrate transport ; Hevea ; Proton pump ; Vacuole
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The relationship between the electrochemical proton gradient, Δ μH+ − , and citrate transport has been studied in tonoplast vesicles from Hevea brasiliensis (the rubber tree). Vesicles were generated from lyophilized samples of fresh vacuoles obtained from the latex sap. Methylamine was used to measure intravesicular pH and lipophilic ions to determine the electrical potential difference (ΔΨ) across the tonoplast. When incubated at pH 7.5 in the absence of ATP, the tonoplast vesicles showed a ΔpH of 0.6 units (interior acid) and a ΔΨ of about-100 mV (interior negative). This potential is thought to be made up of contributions from an H+ diffusion potential, diffusion potentials from other cations and a Donnan potential arising from the presence of internal citrate. In the presence of 5 mol m-3 MgATP the ΔpH was increased to about 1.0 unit and the ΔΨ to about-10 mV. Under these conditions the proton-motive force (Δ p Δ μH+ − /F) became positive and reached +50 mV. These effects were specific to MgATP (ADP and Mg2+ having no significant effect) and were prevented by the protonophore p-trifluoromethoxycarbonylcyanidephenylhydrazone (FCCP). Citrate uptake by the vesicles was markedly stimulated by MgATP; ADP and Mg2+ again had no effect. Nigericin greatly increased ΔpH and this was associated with a large increase in citrate accumulation. The results indicate that the vesicle membrane possesses a functional H+-translocating ATPase. The Δ μH+ − generated by this ATPase can be used to drive citrate uptake into the vesicles. The properties of the tonoplast vesicles are compared with those of the fresh latex vacuoles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00394992
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    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Transport und Integration bei der Evolution der Pflanzen (1978)
    Weinheim : Wiley-Blackwell
    Biologie in unserer Zeit 8 (1978), S. 129-139 
    Details
    ISSN: 0045-205X
    Keywords: Life and Medical Sciences
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/biuz.19780080504
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Streß bei Pflanzen (1990)
    Weinheim : Wiley-Blackwell
    Biologie in unserer Zeit 20 (1990), S. 237-244 
    Details
    ISSN: 0045-205X
    Keywords: Life and Medical Sciences
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Wenn sich der Winter in die Hochlagen und den hohen Norden zurückgezogen hat, stellt manch einer seine Zimmerpflanzen ins Freie, um sie in den Genuß warmer Mairegen und des nun endlich eingetretenen „Wachswetters“ zu bringen. Nur zu oft bewirkt diese gut gemeinte Behandlung aber den gegenteiligen Effekt. Die Blätter bekommen helle Flecken, vergilben, werden schließlich abgeworfen, und man darf froh sein, wenn die Pflanze noch Kraft genug hat, ein neues Blattkleid nachzutreiben. Was ist passiert?
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/biuz.19900200506
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    Paper (German National Licenses)
    Fulltext
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