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1Author    G. W. PohlRequires cookie*
 Title    Spectral Properties of Fluorescent Dyes in Lecithin Vesicles Probes for the Structure of Lipid Bilayer Membranes and for Membrane Potentials  
 Abstract    Three fluorescent dyes (a merocyanin, a cyanin and a modified umbelliferon) have been in­ corporated into vesicles from three different lecithins. Their absorption spectrum, emission spectrum and fluorescence polarization in the lipid vesicles has been studied and compared with the spectral properties in homogeneous organic solutions. The reactivity of lipid bound dyes with reagents in the aqueous phase was investigated. The location use as indicators of phase transitions or membrane 
  Reference    (Z. Naturforsch. 31c, 575 [1976]; received May 10 1976) 
  Published    1976 
  Keywords    Lecithin Vesicles, Fluorescent Probes, Phase Transitions, Membrane Potentials 
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 TEI-XML for    default:Reihe_C/31/ZNC-1976-31c-0575.pdf 
 Identifier    ZNC-1976-31c-0575 
 Volume    31 
2Author    H. Ubert Felle, Hinrich Liihring, Friedrich-W Ilhelm BentrupRequires cookie*
 Title    Serine Transport and Membrane Depolarization in the Liverwort Riccia fluitans  
 Abstract    The plasmalemma of thallus cells o f the aquatic liverwort, R icciaßuitans, is reversibly depolar­ ized by L-and D-serine. At 0.1 mM K + in the medium, the depolarization saturates at 50 mV; half-maximal depolarization occurs at 13 hm L-serine and 30 ^m D-serine, respectively. Uptake of 14C-labelled L-serine depends upon the K + concentration and is sensitive to the membrane potential as indicated by its reduction through 1 m M sodium cyanide. We propose that serine binds to and is transported by an electrogenic carrier. However, an interaction of serine with K + channels o f the membrane seems also possible. 
  Reference    Z. Naturforsch. 34c, 1222—1223 (1979); received September 10 1979 
  Published    1979 
  Keywords    Serine, Membrane Potential, Electrogenic Carrier, Riccia 
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 TEI-XML for    default:Reihe_C/34/ZNC-1979-34c-1222.pdf 
 Identifier    ZNC-1979-34c-1222 
 Volume    34 
3Author    Marc Symons, Anthony CroftsRequires cookie*
 Title    Flash-Induced Electrochromic Band Shifts, is It a Simple Mechanism?  
 Abstract    The flash-induced carotenoid bandshifts have been studied for various strains of both Rho-dopseudomonas sphaeroides and capsulata. A technique for calculating shifts o f isobestic points down to 0.05 nm is described. To this end, special attention has been paid to the appropriate cor­ rection for reaction center absorbance changes occuring concommitantly with the carotenoid bandshifts. Plots of the wavelength o f the isobestic point versus the corresponding absorption changes at the maximum o f the difference spectrum have been made, suggesting the existence o f different pools of carotenoids. The various pools of carotenoids seem to have different sizes, in­ ducing non-linearities in the plots. In some cases spectral differences of the pools have to be assumed. A possible interpretation o f the results would be that each electrogenic span of the electron transport chain is to be associated with its own pool of carotenoids, all the pools behaving in somewhat independant way. We discuss possible difficulties in making those measurements. 
  Reference    Z. Naturforsch. 35c, 139—144 (1980); received August 16 1979 
  Published    1980 
  Keywords    Electrochromism, Carotenoids, Electron Transport, Membrane Potential, Photosynthesis 
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 TEI-XML for    default:Reihe_C/35/ZNC-1980-35c-0139.pdf 
 Identifier    ZNC-1980-35c-0139 
 Volume    35 
4Author    C. Hristof Klugham, Er, Ulrich SchreiberRequires cookie*
 Title    Analysis of Light-Induced Absorbance Changes in the Near-Infrared Spectral Region I. Characterization of Various Components in Isolated Chloroplasts  
 Abstract    Light-induced absorbance changes in the near-infrared (N IR) spectral region (7 0 0 -9 5 0 nm) are analyzed in isolated spinach chloroplasts using pulsed light-emitting diodes as modulated measuring light sources. With chloroplasts under coupled conditions the light-induced signal is dominated by a relatively slow scattering change displaying a flat difference spectrum. More specific changes can be distinguished by faster induction and relaxation kinetics and in the presence o f valinomycin/nigericin which prevents scattering changes. Besides the dominant P700 change, with a narrow bleaching band around 703 nm and a broad absorbance increase between 750 and 850 nm (peak at 815 nm) the following absorbance changes were identified in the NIR: 1) An absorbance increase caused by plastocyanin (PC) oxidation, with a relatively flat spectrum. 2) An absorbance decrease gaining amplitude towards longer wavelengths, which reflects reduction o f a low potential acceptor o f PS I different from ferredoxin. 3) A field indicating absorbance decrease peaking around 730 nm, the properties o f which correspond to those o f P 515. 4) An uncoupler insensitive absorbance decrease stimulated by dark adaptation and anaero­ bic conditions, the difference spectrum o f which resembles that o f ferredoxin reduction. The relative contributions o f P700 and PC to the overall oxidized-reduced difference spec­ trum are determined by redox titration. At 706 nm, 815 nm and 950 nm the P 700/PC is -119/ 19, 67/37 and 31/69, respectively. From these ratios and the molar extinction coefficients a molar P 700/PC stoichiometry o f 1 /3 is determined. 
  Reference    Z. Naturforsch. 46c, 233 (1991); received November 19 1990/January 2 1991 
  Published    1991 
  Keywords    Plastocyanin, Membrane Potential, Ferredoxin, Light Scattering, Photosynthesis 
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 TEI-XML for    default:Reihe_C/46/ZNC-1991-46c-0233.pdf 
 Identifier    ZNC-1991-46c-0233 
 Volume    46 
5Author    J. Benavente, A. M. Uñoz, A. HerediaRequires cookie*
 Title    Ionic Permeabilities of Different Isolated Fruit Cuticles Calculated by Conductivity and Membrane Potential Measurements  
 Abstract    Membrane potential and electrical resistance for two isolated fruit cuticular membranes (tomato and pepper cuticles) were measured for different NaCl solutions (10-3 m < C < 5 x l 0 ~ 2 m). From these experimental results some membrane characteristic parameters were obtained such as cation transport number, t+, which represents the fraction of the electric current transported by the cation, / + , with respect to the total current, / x (t+ = / + / / t) , and ionic permeabilities. P + and P_, for both membranes. Concentration dependence of these parameters was also considered. A comparative study between both types of fruit cuticles is also made. It was found that cation transport number, ionic permeabilities and electrical resistances are quite similar for both membranes. 
  Reference    Z. Naturforsch. 49c, 615—618 (1994); received May 9/June 8 1994 
  Published    1994 
  Keywords    Fruit Cuticles, Membrane Potential, Membrane Conductivity, Ionic Permeabilities 
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 TEI-XML for    default:Reihe_C/49/ZNC-1994-49c-0615.pdf 
 Identifier    ZNC-1994-49c-0615 
 Volume    49 
6Author    K. Urt Schefczik, Wilhelm SimonisRequires cookie*
 Title    Action of Lindane on the Current-Voltage Relationship in the Plasma Membrane of Elodea under Passive Conditions  
 Abstract    Side effects of the chlorinated hydrocarbon insecticide Lindane on the plasma membrane of the submerged macrophytic fresh-water plant Elodea densa were studied. Single glass microelectrodes were inserted into single cells and membrane potential, membrane resistance and electrode resistance were recorded using a new designed electrophysiological monitoring system ("ELM 2"). The current-voltage relationship in the plasma membrane of Elodea cells under passive conditions is nearly linear for relaxing current pulses up to 10—8 amperes. Lindane treatment, produced first (3.5 hours) a strong nonlinearity in current-voltage relationship with increased membrane resistance for inward current flow, and later (24.5 hours) an increased membrane resistance both for inward and outward current flow. It is discussed that the earlier reported lowering of the potassium selectivity in the plasma membrane of Elodea after Lindane treatment will be the reason for the alterations of current-voltage relationship. 
  Reference    Z. Naturforsch. 34c, 1072—1074 (1979); received June 5 1979 
  Published    1979 
  Keywords    Side Effects of Lindane, Elodea densa Plasma Membrane, Current-Voltage Relationship, Membrane Potential, Ionic Relations 
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 TEI-XML for    default:Reihe_C/34/ZNC-1979-34c-1072.pdf 
 Identifier    ZNC-1979-34c-1072 
 Volume    34