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  • 1
    Electronic Resource
    Electronic Resource
    Respirational activity of Chlorella fusca monitored by in vivo P-31 NMR (1985)
    Springer
    European biophysics journal 13 (1985), S. 89-97 
    Details
    ISSN: 1432-1017
    Keywords: 31P NMR ; respiration ; polyphosphate ; Chlorella ; intracellular pH
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract Energy metabolism during dark respiration of the green alga Chlorella fusca was investigated by 31P NMR spectroscopy. The kinetics of the transition from anaerobic to aerobic conditions (and vice versa) was followed with a temporal resolution of 16 s. This transition is accompanied by a shift of the cytoplasmic pH from 6.8 to 7.4, while the vacuolar pH remains constant. Simultaneously, an increase in the concentration of nucleoside-triphosphates and a decrease in the concentration of cytoplasmic orthophosphate take place, as well as the formation of “mobile” polyphosphates. The concentration of ATP and P i reach steady-state levels within 30 s. Upon the reverse transition, from aerobic to anaerobic conditions, steady-state concentrations are obtained only after 3 min.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00256529
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  • 2
    Electronic Resource
    Electronic Resource
    The cytoplasmic pH in photosynthesizing cells of the green alga Chlorella fusca, measured by P-31 NMR spectroscopy (1987)
    Springer
    Archives of microbiology 147 (1987), S. 25-29 
    Details
    ISSN: 1432-072X
    Keywords: Chlorella fusca ; Cyclic photophosphorylation ; Cytoplasmic pH ; Green algae ; P-31 NMR spectroscopy ; Photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract P-31 NMR investigations were performed with the green alga Chlorella fusca under anaerobic conditions in the dark and in the light. In spectra of cells in the dark the signal of intracellular, nonvacuolar Pi indicates a pH in its chemical environment of 7.0–7.2. Upon illumination this signal looses intensity and shifts to lower field, corresponding to a pH of 7.7. Further downfield no other signal that could be attributed to a Pi-pool in more alkaline environment was detected. By the use of 2-deoxyglucose-6-phosphate as an indicator of cytoplasmic pH, this Pi-signal was assigned to the cytoplasm. The pH increase in the cytoplasm upon transfer of cells from the dark to the light is the same as that previously observed upon transfer of cells from anaerobic to aerobic conditions. In cells performing only cyclic photophosphorylation the cytoplasmic pH is lower than in photosynthesizing cells but still 0.2 pH units higher than in the cells in the dark. The reasons for the missing of a signal of stromal Pi and for the difference in cytoplasmic pH in photosynthesizing cells and those capable only of cyclic photophosphorylation are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00492900
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  • 3
    Electronic Resource
    Electronic Resource
    P-31 in-vivo NMR investigation on the function of polyphosphates as phosphate-and energysource during the regreening of the green alga Chlorella fusca (1989)
    Springer
    Archives of microbiology 152 (1989), S. 167-171 
    Details
    ISSN: 1432-072X
    Keywords: Chlorella fusca ; Green alga ; Nitrogen starvation ; Polyphosphates ; P-31 in-vivo NMR spectroscopy ; Regreening
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The green alga Chlorella fusca accumulates polyphosphates under conditions of nitrogen starvation while deassembling the photosynthetic apparatus. The polyphosphate content of cells regreening after resupply with nitrate under different culture conditions was investigated by P-31 in-vivo NMR spectroscopy. Neither phosphate deficiency nor anaerobiosis during the first hours of regreening inhibited the recovery of the cells. Polyphosphates were degraded during regeening. Differences in the amount of polyphosphates of phosphate supplied and deficient cells occurred only after more then 8 h. After 16 h phosphate deficient cells had still 75% of the polyphosphate content of phosphate suppled cells. In cells kept under anaerobic conditions polyphosphate degradation was much higher than in oxygen supplied cells. After 8 h they contained less than 50% of the polyphosphate content of oxygen supplied cells. These data suggest that polyphosphates serve as obligatory phosphate source during regreening and may be used as an energy source.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00456096
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  • 4
    Electronic Resource
    Electronic Resource
    Distribution of polyphosphates in cell-compartments of Chlorella fusca as measured by 31P-NMR-spectroscopy (1986)
    Springer
    Archives of microbiology 144 (1986), S. 48-54 
    Details
    ISSN: 1432-072X
    Keywords: Chlorella fusca ; Green alga ; 31P-NMR-spectroscopy ; Polyphosphates ; Cellular localization ; Metal-ion complexation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In suspensions of the green alga Chlorella fusca the influence of high pH and high ethylene-diamine-tetraacetic acid concentrations in the external medium, of French-press and perchloric acid extraction of the cells and of alkalization of the intracellular pH on the polyphosphate signal in 31P-nuclear magnetic resonance (31P NMR) spectra was investigated. The results show that part of the polyphosphates of asynchronous Chlorella cells are located outside the cytoplasmic membrane and complexed with divalent metal-ions. These polyphosphates are tightly bound to the cell wall and/or the cytoplasmic membrane and are not susceptible to hydrolyzation by strong acid at room temperature, in contrast to the intracytoplasmic polyphosphates. Upon alkalization of the internal pH of Chlorella cells, polyphosphates, previously not visible in the spectra become detectable by 31P-NMR-spectroscopy. 31P-NMR spectroscopic monitoring of polyphosphates during gradual alkalization of the extra-and intracellular space is proposed as a quick method for the estimation of the cellular polyphosphate content and distribution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00454955
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  • 5
    Electronic Resource
    Electronic Resource
    N-15 in vivo NMR spectroscopic investigation of nitrogen deprived cell suspensions of the green alga Chlorella fusca (1989)
    Springer
    Archives of microbiology 151 (1989), S. 434-438 
    Details
    ISSN: 1432-072X
    Keywords: Amino acid metabolism ; Chlorella fusca ; Green alga ; N-15 in vivo NMR spectroscopy ; Nitrogen deficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The possibility to apply N-15 in vivo NMR spectroscopy to study algal N-metabolism has been investigated. N-15 labelled cells of the green alga Chlorella fusca, subjected to nitrogen starvation and N-14 labelled cells supplied with K15NO3 after prolonged nitrogen starvation were monitored by N-15 in vivo NMR spectroscopy at different times after the change in their nitrogen supply. During 20–40 min, necessary for the acquisition of 1 spectrum, the cells were under dark anaerobic conditions, but the relative amounts of the metabolites detected did not change. Signals from 2 acid amides, from the side chain nitrogens of arginine and lysine, from prolin as well as 4 signals from α amino groups of amino acids were detected. Besides two signals not yet reported in the literature were found. They may be due to amino compounds, but not to amino acids. The amount of free amino acids in the cells increases not only upon resupply of nitrogen starved cells with nitrate but also during the first hours after nitrate depletion. The spectra obtained from N-15 labelled autospores show that N-15 in vivo NMR spectroscopy can be applied to the investigation of N metabolism of the cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00416603
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  • 6
    Electronic Resource
    Electronic Resource
    The dependence of the cytoplasmic pH in aerobic and anaerobic cells of the green algae Chlorella fusca and Chlorella vulgaris on the pH of the medium as determined by 31P in vivo NMR spectroscopy (1990)
    Springer
    Archives of microbiology 153 (1990), S. 254-258 
    Details
    ISSN: 1432-072X
    Keywords: Aerobiosis ; Anaerobiosis ; Chlorella ; Cytoplasmic pH ; External pH ; 31P in vivo NMR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The pH in the cytoplasm of aerobic and anaerobic cells of the green algae Chlorella fusca and Chlorella vulgaris was determined in dependence on the pH of the external medium, which was varied between pH 3 and pH 10. In aerobic cells of both species the cytoplasmic pH is maintained at a value above 7.2 even at an external pH of 3 and below 7.8 at an external pH of 10. In anaerobic cells the cytoplasmic pH shows linear dependence on external pH in the range of pH 6 to 9 (cytoplasmic pH 6.9 to 7.2), while below an external pH of 6 cytoplasmic pH is maintained at about 6.5.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00249077
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  • 7
    Electronic Resource
    Electronic Resource
    Investigation of intracellular phosphate pools of the green alga Chlorella using 31P nuclear magnetic resonance (1984)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 22 (1984), S. 364-368 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 31P NMR measurements were performed in order to study the intracellular phosphate pools of the green alga Chlorella fusca. Cells of asynchronous cultures contain a large pool of polyphosphates, whereas the amount of polyphosphates in cells of synchronous cultures depends on the state of differentiation. The assignment of extracellular and intracellular inorganic orthophosphate is achieved by changing the pH, whereas the intracellular compartmentation of inorganic orthophosphates and sugar phosphates is shown during irradiation of the cells with light within the NMR spectrometer.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270220603
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