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  • 2020-2023
  • 1995-1999  (2)
  • Nitrate reductase  (1)
  • PAM fluorescence  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Photoinhibition by visible and ultraviolet radiation in the red macroalga Porphyra umbilicalis grown in the laboratory (1999)
    Springer
    Plant ecology 145 (1999), S. 351-358 
    Details
    ISSN: 1573-5052
    Keywords: oxygen measurements ; PAM fluorescence ; photoinhibition ; Porphyra ; rhodophyta ; ultraviolet radiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photosynthetic oxygen production and PAM fluorescence measurements were used to follow photoinhibition in the red macroalga Porphyra umbilicalis. Exposure to simulated solar radiation caused inhibition of the effective photosynthetic quantum yield from which the thalli partially recovered in the shade in subsequent hours. There were no significant differences between samples exposed to unfiltered radiation and those exposed to radiation from which increasing portions of UV radiation had been removed indicating that the thalli are well adapted to current levels of solar PAR and UV radiation. This notion was supported by the finding of high concentrations of UV screening pigments which were even enhanced by exposure to increased UV radiation. However, when exposed to (only) UV radiation about 50% higher than that encountered by the organisms in their natural habitat, the photosynthetic yield decreased slowly and did not show any recovery even when the degree of inhibition did not exceed 10%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009833520770
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Optimized nitrate reductase assay predicts the rate of nitrate utilization in the halotolerant microalga Dunaliella viridis (1997)
    Springer
    Journal of applied phycology 9 (1997), S. 99-106 
    Details
    ISSN: 1573-5176
    Keywords: Nitrate reductase ; in situ enzymatic activity ; Dunaliella viridis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An in situ method for measuring nitrate reductase (NR) activity in Dunaliella viridis was optimized in terms of incubation time, concentration of KNO3, permeabilisers (1-propanol and toluene), pH, salinity, and reducing power (glucose and NADH). NR activity was measured by following nitrite production and was best assayed with 50 mM KNO3, 1.2 mM NADH, 5% 1-propanol (v/v), at pH 8.5. The estimated half-saturation constant (Ks) for KNO3 was 5 mM. Glucose had no effect as external reducing power source, and NADH concentrations 〉1.2 mM inhibited NR activity. Nitrite production was linear up to 20 min; longer incubation did not lead to higher nitrate reduction. The use of the optimized assay predicted the rate of NO 3 − removal from the external medium by D. viridis with high degree of precision.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007978512458
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
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