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1Author    GeorgH. Schmid, Pierre ThibaultRequires cookie*
 Title    Evidence for a Rapid Oxygen-Uptake in Tobacco Chloroplasts  
 Abstract    A fast oxygen uptake, induced by a sequence of short (5 /usee) saturating flashes was observed in chloroplasts of wild type tobacco and two chlorophyll-deficient tobacco mutants. One of the chlorophyll mutants is the earlier described variegated tobacco NC 95. Chloroplasts of this mutant exhibit only photosystem I mediated photoreactions, hence the observed oxygen uptake is to be associated with photosystem I. This is further substantiated by the fact that the oxygen uptake is insensitive to DCMU in the two chloroplast types used, which have both photosystems fully func­ tioning. The uptake depends on the addition of electron acceptors like p-benzoquinone in intact chloroplasts or on p-benzoquinone or ferricyanide in chloroplasts that have lost the envelope. In dark adapted chloroplasts, therefore, under these conditions the overall apparent gas exchange in the first two flashes is consumption. Although the uptake is slower than photosynthetic oxygen evolution it clearly affects the oxygen yield in the flash sequences. This is demonstrated by several experiments in which the apparent oxygen consumption in the absence of DCMU oscillates with a periodicity of four. We have indications that in chloroplasts of the tobacco aurea mutant Su/su the oxygen uptake is faster than in wild type chloroplasts. 
  Reference    Z. Naturforsch. 34c, 414 (1979); received February 14 1979 
  Published    1979 
  Keywords    Chloroplasts, Oxygen uptake, Oscillations, Photosynthesis 
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 TEI-XML for    default:Reihe_C/34/ZNC-1979-34c-0414.pdf 
 Identifier    ZNC-1979-34c-0414 
 Volume    34 
2Author    Vijay Kumar, Sharma3, Wolfgang Engelmannb, Anders JohnssoncRequires cookie*
 Title    Effects of Static Magnetic Field on the Ultradian Lateral Leaflet Movement Rhythm in Desmodium gyrans  
 Abstract    The rhythmic leaflet movements of the plant Desmodium gyrans (L.f.) DC slow down in the presence of a static magnetic field. The leaflet positions were digitally retrieved from sequential CCD cam era images of the moving leaflets. The experiments were performed under constant light (ca. 500 lux) and tem perature (about 20 °C) conditions. The period of the leaflet was then around 5 min. Leaflets moving up and down in a magnetic field of approximately 50 mT flux density increased the period by about 10% due to a slower motion in the "up" position. Since during this position a rapid change of the extracellular potentials of the pulvinus occurs, it is proposed that the effects are mediated via the electric processes in the pulvinus tissue. 
  Reference    Z. Naturforsch. 55c, 638 (2000); received January 18/M arch 20 2000 
  Published    2000 
  Keywords    Oscillations, Video Imaging, Ion Movements 
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 TEI-XML for    default:Reihe_C/55/ZNC-2000-55c-0638.pdf 
 Identifier    ZNC-2000-55c-0638 
 Volume    55 
3Author    Igor Schreiber, Milan Kubíček, M. Iloš MarekRequires cookie*
 Title    Impaired Diffusion Coupling-Source of Arrhythmia in Cell Systems  
 Abstract    A detailed analytical and numerical analysis of a simple reaction-diffusion model of the source of non-homogeneities and arrhythmias in an originally homogeneous reaction system is pre­ sented. Solution, bifurcation and evolution diagrams are used to describe the behaviour of the model. It is shown that under certain conditions steady and/or oscillatory nonhomogeneous states are the only stable solutions of the model. These phenomena are essentially not dependent on a particular reaction kinetics. A possible relevance to some biological situations is discussed. 
  Reference    Z. Naturforsch. 39c, 1170—1179 (1984); received December 3 1982/May 16 1984 
  Published    1984 
  Keywords    Reaction-Diffusion Systems, Dissipative Structures, Oscillations, Synchronization, Arrhythmias 
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 TEI-XML for    default:Reihe_C/39/ZNC-1984-39c-1170.pdf 
 Identifier    ZNC-1984-39c-1170 
 Volume    39 
4Author    FriedrichFranz SeeligRequires cookie*
 Title    System-theoretical Investigation of Possible Oscillatory States in the Hydroformylation Process in an Open Isothermal System Hydroformylation  
 Abstract    The kinetic model for the hydroformylation process as given in a previous paper (SEELIG 1) is extended in as far as the concentrations of all three substrates (olefin, H2, CO) are allowed to move freely, whilst in the first investigation this was the case only for CO, the concentrations of olefin and H2 being kept constant. So the derived hysteresis loop of [CO] vs influx of CO is shifted back and forth by the varying [olefin] and [H2], causing oscillations for particular combinations of the parameters. These oscillations are due to the substrate inhibition by CO and are not the result of instabilities of some external control circuit; so they would occur even in a perfectly isothermal open system. 
  Reference    (Z. Naturforsch. 31b, 929—934 [1976]; received March 5 1976) 
  Published    1976 
  Keywords    Oxo-synthesis, System Theory, Stability Analysis, Oscillation, Substrate Inhibition 
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 TEI-XML for    default:Reihe_B/31/ZNB-1976-31b-0929.pdf 
 Identifier    ZNB-1976-31b-0929 
 Volume    31 
5Author    É. Va, H. Ideg, SándorD. Em EterRequires cookie*
 Title    Binary Oscillation of Delayed Luminescence: Evidence of the Participation of Qb in the Charge Recombination  
 Abstract    The flash-induced oscillation of a slowly decaying component of delayed luminescence (half time ~ 42 s) was investigated in spinach chloroplasts for various redox states of the secondary acceptor pool (Q B)-In preilluminated chloroplasts (30 s light followed by 5 min dark) the slow component exhibited a period-4 oscillation as a function of flash number. Upon oxidation of a major part of the QB pool by dark-adaptation or by ferricyanide treatment of chloroplasts, the period-4 oscillation was converted into a period-2 oscillation, providing direct experimental evi­ dence of the participation of QB in the charge recombination reaction. The measured oscillatory patterns could be simulated in model calculations by assuming that the slow component originates from charge recombination of the redox couples S2Q| 
  Reference    Z. Naturforsch. 40c, 827—831 (1985); received May 23/July 24 1985 
  Published    1985 
  Keywords    Delayed Luminescence, Oscillation, Oxygen Evolution, Secondary Quinone Acceptor, Chloroplast 
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 TEI-XML for    default:Reihe_C/40/ZNC-1985-40c-0827.pdf 
 Identifier    ZNC-1985-40c-0827 
 Volume    40