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  • 1
    Electronic Resource
    Electronic Resource
    Performance of the extreme ultraviolet high resolution undulator beamline BW3 at Hasylab: First results and time-of-flight spectroscopy : Proceedings of the 5th international conference on synchrotron radiation instrumentation (1995)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 66 (1995), S. 1732-1734 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The extreme ultraviolet beamline BW3 at Hasylab is a state of the art beamline for the energy range 15–2000 eV consisting of a triple undulator equipped with a modified high-flux SX-700 plane grating monochromator. The first three optical elements of the beamline are made of graphite coated with SiC to withstand the high heat load at the 4.5 GeV storage ring Doris III. Excellent spectral resolution of the order of 104 at the nitrogen K edge at 400 eV is obtained by replacing the elliptical focusing mirror of the original SX-700 design by a spherical mirror with very small tangent errors and with a large focal length in order to suppress spherical aberrations. In the energy range 50–1700 eV a photon flux of 1011–1013/s is obtained in a bandpass of 0.1%. Photoionization and photoemission measurements on atoms, molecules, and clusters making use of time-of-flight techniques demonstrate the excellent performance of the beamline. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1145833
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  • 2
    Electronic Resource
    Electronic Resource
    Affinity, capacity and oxygen sensitivity of two different mechanisms for bicarbonate utilization in Ulva lactuca L. (Chlorophyta) (1999)
    Oxford, UK : Blackwell Science Ltd.
    Plant, cell & environment 22 (1999), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Ulva lactuca, collected on the west coast of Sweden at the end of May, was able to utilize the HCO3− pool of seawater only through extracellular dehydration via carbonic anhydrase, followed by uptake of the CO2 formed. A decrease in the CO2 supply via this mechanism resulted in the gradual development of an additional method of HCO3− utilization, namely a direct uptake of HCO3−. Photosynthesis could then be supported by either a ‘HCO3− dehydration mechanism’ or a ‘HCO3− uptake mechanism’. Through selective inhibition of either of these mechanisms, the physiological properties of the other could be assessed. These properties suggest that the HCO3− uptake mechanism of U. lactuca is important under conditions when low concentrations of inorganic C, high pH and high external O2 concentrations would limit photosynthesis supported by the HCO3− dehydration mechanism. Such conditions may occur during intense irradiation of the alga in rockpools or in shallow bays with low rates of water exchange. The results are discussed in relation to a possible coupling between mechanisms for inorganic C acquisition and cell structure (or even morphology) of green macroalgae. They also illustrate some necessary precautions when using Michaelis–Menten kinetics for estimations of Vmax and K1/2 values.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3040.1999.00470.x
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  • 3
    Electronic Resource
    Electronic Resource
    Growth and nitrate uptake properties of plants grown at different relative rates of nitrogen supply. II. Activity and affinity of the nitrate uptake system in Pisum and Lemna in relation to nitrogen availability and nitrogen demand (1989)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 12 (1989), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Net nitrate uptake rates were measured and the kinetics calculated in non-nodulated Pisum sativum L. cv. Marma and Lemna gibba L. adapted to constant relative rates of nitrate-N additions (RA), ranging from 0.03 to 0.27 d−1 for Pisum and from 0.05 to 0.40 d−1 for Lemna, Vmax of net nitrate uptake (measured in the range 10 to 100 mmol m−3 nitrate, i.e. ‘system I’) increased with RA in the growth limiting range but decreased when RA exceeded the relative growth rate (RGR), Km was not significantly related to changes in RA. On the basis of previous 13N-flux experiments, it is concluded that the differences in Vmax at growth limiting RA are attributable to differences in influx rates. Linear relationships between Vmax and tissue nitrogen concentrations were obtained in the growth limiting range for both species, and extrapolated intercepts relate well with the previously defined minimal nitrogen concentrations for plant growth (Oscarson, Ingemarsson & Larsson, 1989). Analysis of Vmax for net nitrate uptake on intact plant basis in relation to nitrogen demand during stable, nitrogen limited, growth shows an increased overcapacity at lower RA values in both species, which is largely explained by the increased relative root size at low RA. A balancing nitrate concentration, defined as the steady state concentration needed to sustain the relative rate of increase in plant nitrogen (RN), predicted by RA, was calculated for both species. In the growth limiting range, this value ranges from 3.5 mmol m−3 (RA 0.03 d−1) to 44 mmol m−3 (RA 0.21 d−1) for Pisum and from 0.2 mmol m−3 (RA 0.05 d−1) to 5.4 mmol m−3 (RA 0.03 d−1) for Lemna. It is suggested that this value can be used as a unifying measure of the affinity for nitrate, integrating the performance of the nitrate uptake system with nitrate flux and long term growth and demand for nitrogen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1989.tb01640.x
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  • 4
    Electronic Resource
    Electronic Resource
    Growth and nitrate uptake properties of plants grown at different relative rates of nitrogen supply. I. Growth of Pisum and Lemna in relation to nitrogen (1989)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 12 (1989), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract The relations between growth and internal nitrogen concentrations were investigated in nonnodulated Pisum sativum L. cv. Marma and Lemna gibba L. grown at relative rates of nitrate-N additions (RA) varying from 0.03 to 0.27 d 1(Pisum) and 0.05 to 0.40 d 1 (Lemna). At RA≤0.21 d 1(Pisum) and ≤0.30 d 1 (Lemna), the relative growth rate (RGR) correlated well with RA whereas higher RA was not met by any further increawse in growth rate. The tissue nitrogen concentrations at growth-limiting RA increased linearly with RGR. The slope of these lines indicate a maximum nitrogen productivity (amount of biomass formed per unit nitrogen and time) of 14.4 g DW g 1 Nd 1 for Pisum and 15.9 g DW g 1 N d 1 for Lemna. Extrapolation of the plots to RGR=0 yielded intercepts of 10–15 mg N g−1 DW for Pisum tissue, whereas for Lemna the intercepts were closer to the origin than for Pisum. These intercepts formally define a fraction of the total plant nitrogen that appears not to be active in production of new biomass, her termed ‘non-growth nitrogen’. The partitioning of nitrogen as well as biomass to the roots increased at low RA, and is discussed in relation to activity of shoots and roots, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1989.tb01639.x
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  • 5
    Electronic Resource
    Electronic Resource
    Translocation and cycling through roots of recently absorbed nitrogen and sulphur in wheat (Triticum aestivum) during vegetative and generative growth (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 82 (1991), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 15N-Nitrate and 35S-sulphate labelling experiments were performed with spring wheat (Triticum aestivum L. cv. Timmo) 44. 64, 79, 95 and 115 days after sowing (growth stages arbitrarily denoted I to V). Label was fed to the plants via a fraction of the root system, termed “donor root”, whereas the rest of the root (“receiver root”) was fed non-labelled nutrient solution. Net uptake rates for both nitrate and sulphate per unit root weight changed little from growth stage I to IV, but were considerably lower at stage V. On a whole-plant weight basis, uptake declined from stage I to IV, because root contribution to total plant weight declined. Between 80 and 95% of absorbed label was translocated to the shoot at all growth stages. At stage V, up to 30% of absorbed label was recovered in the ears. Labelling of the receiver root indicated that, at all growth stages, 10 to 17% of N and 12 to 32% of S translocated to the shoot was retranslocated to the root. This corresponds to between 35 and 85% of the label actually recovered in the roots. Analysis of 15N-labelling of xylem sap collected from receiver roots at growth stages I to IV indicated that about half of the reduced N in the sap is derived from cycling through roots of recently assimilated N. Evidence of cycling was also obtained at stage V. Labelled sulphate was the only form of S cycled in the plant, but it accounted for only 1 to 7% of the sulphate in the xylem sap.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1991.tb02916.x
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  • 6
    Electronic Resource
    Electronic Resource
    Relations between uptake and utilization of NO−3 in Pisum growing exponentially under nitrogen limitation (1986)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 67 (1986), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The utilization and translocation of nitrogen was investigated in exponentially growing, nitrogen-limited Pisum sativum L. cv. Marma. The plants were given N daily at exponentially increasing, although suboptimal, relative nitrogen addition rates (RN) calculated to yield a relative increment in N of 0.06 day−1 and 0.12 day−1. After 10 days of NO−3 additions (26 days after sowing), the relative growth rate more or less equaled RN. Uptake of NO−3 was several-fold higher than the N requirement for the growth rate set by RN. The daily addition of NO−3 was taken up after 7 to 8 h, resulting in a cyclic behaviour in the NO−3 utilization. During the phase of net NO−3 influx, the filling phase (0 to 8 h), in vitro nitrate reductase activity (NR activity) and intracellular levels of soluble N in the root increased. In the phase of no net influx of NO−3 the depletion phase (8 to 24 h), the plants were entirely dependent on stored N. During this phase both in vitro NR activity and intracellular levels of soluble N decreased. Also the calculated actual rate of NO−3 reduction was high in the filling phase, while it was close to zero in the depletion phase. The pattern of these fluctuations indicates that the regulation of NO−3 utilization involves an interplay between transmembrane fluxes of NO−3, the cytosolic NO−3 concentration and NR activity. Cyclic fluctuations in N-containing compounds were also found in the xylem. Nitrogen was mainly transported as amino acids. The pattern of NO−3 transport in the xylem and the fluctuations in the shoot of in vitro NR activity indicate that a reasoning similar to that for the regulation of NO−3 assimilation in the root also applies for the shoot. The results also indicate a substantial supply of amino acids to the xylem through recirculation from the shoot.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1986.tb01271.x
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  • 7
    Electronic Resource
    Electronic Resource
    Separation of presumptive plasma membranes from mitochondria by partition in an aqueous polymer two-phase system (1981)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 51 (1981), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Light-induced absorbance changes (LIAC), indicating the reversible reduction of a b-type cytochrome, and with a possible connection to blue light photomorphogenesis, have been found in a presumptive plasma membrane rich centrifuge fraction from LIAC could be due to plasma membrane vesicles turned inside out or to cytochromes localized in other organelles. Phase partition proved to be a rapid method (results technique membrane particles are separated according to differences in surface properties rather than size and density. LIAC could be separated into two fractions: one partitioning into the polyethylene glycol rich upper phase and another preferring the dextram rich lower phase. Mitochondria (cytochrome c oxidase) were recovered in the lower phase. A dual distribution of LIAC was found with all materials tested: corn coleoptiles, corn shoots, barley shoots and cauliflower inflorescences. About 80–90% of the cytochromes in the upper phase were related to LIAC, whereas only 10–15% of those in the lower phase were of this kind. The LIAC preferring the upper phase was probably bound to the plasma membrane, since plasma membrane vesicles are known to have a high partition in these phase systems. The lower phase LIAC could be due to plasma membrane vesicles turned inside out or to cytochromes localized in other organelles. Phase partition proved to be a rapid method (results within one hour after the initial pelleting) for purification of presumptive plasma membranes, yielding a preparation which contained five times less mitochondrial contamination than the preparation obtained with sucrose gradient centrifugation (the 33/45% w/w sucrose interface fraction).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1981.tb05571.x
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  • 8
    Electronic Resource
    Electronic Resource
    Photophosphorylation in Scenedesmus in vivo: O2 evolution, ATP pools and transients, and phosphate binding during photoreduction of NO3−, NO2− and CO2 (1980)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 48 (1980), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The relation between light-induced electron transport with NO3−, NO2− or CO2 as acceptors, ATP pools and transients in dark-light-dark transitions, and phosphate uptake was examined in phosphorus-starved cells of Scenedesmus obtusiusculus Chod. Net O2 evolution at saturating light was around 6 μmol × (mg chlorophyll × h)−1 in the absence of any acceptor, but reached average rates of 21, 65 and 145 μmol × (mg chlorophyll × h)−1 upon additions of 5 mM KNO3, KNO2 and KHCO3, respectively. The apparent rate of photophosphorylation in transition experiments was only a few percent of the rate calculated from CO2-dependent O2 evolution. Blocking non-cyclic electron transport with DCMU inhibited phosphate assimilation, but acceleration of non-cyclic electron flow by addition of NO3− or NO2− did not stimulate phosphate assimilation as compared to the situation without an acceptor. A functional non-cyclic system might primarily be needed for an efficient shuttle transfer of ATP from the chloroplast to the cytoplasm. An inhibition of the non-cyclic system due to lack of reducible substrates accelerates the cyclic system and thus indicates a regulation mechanism between the two systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1980.tb03263.x
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  • 9
    Electronic Resource
    Electronic Resource
    The sucrose carrier of the plant plasma membrane. I. Differential affinity labeling
    Amsterdam : Elsevier
    Biochimica et Biophysica Acta (BBA)/Biomembranes 978 (1989), S. 56-64 
    Details
    ISSN: 0005-2736
    Keywords: (Sugar beet) ; 42 kDa ; Differential affinity labeling ; Plant plasma membrane ; Plant plasmalemma ; Protein ; Sucrose carrier ; Sucrose transport
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Medicine , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0005-2736(89)90498-7
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  • 10
    Electronic Resource
    Electronic Resource
    The sucrose carrier of the plant plasma membrane. II. Immunological characterization
    Amsterdam : Elsevier
    Biochimica et Biophysica Acta (BBA)/Biomembranes 978 (1989), S. 65-71 
    Details
    ISSN: 0005-2736
    Keywords: (Sugar beet) ; Plant plasma membrane ; Plant plasmalemma ; Polyclonal antibody ; Protein, 42 kDa ; Scurose transport ; Sucrose carrier
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Medicine , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0005-2736(89)90499-9
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