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  • 1
    Online Resource
    Online Resource
    Inorganic Nitrogen in Plants and Microorganisms : Uptake and Metabolism. (1990)
    Berlin, Heidelberg :Springer Berlin / Heidelberg,
    Details
    Keywords: Nitrogen-Metabolism-Congresses. ; Electronic books.
    Type of Medium: Online Resource
    Pages: 1 online resource (366 pages)
    Edition: 1st ed.
    ISBN: 9783642758126
    URL: https://ebookcentral.proquest.com/lib/geomar/detail.action?docID=6498487
    Language: English
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    GEOMAR EBL
  • 2
    Electronic Resource
    Electronic Resource
    Blue-light requirement for the biosynthesis of an NO2− transport system in the Chlamydomonas reinhardtii nitrate transport mutant S10* (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: The blue-light requirement for the biosynthesis of nitrite reductase and an NO2– transport system was studied in Chlamydomonas reinhardtii mutant S10. The only oxidized nitrogen species that could be taken up by this mutant was NO2–, due to the presence of NO2– transport systems and the absence of high-affinity NO3– transporters. NH4+-grown cells required illumination with blue light to recover the ability to take up NO2– when resuspended in an NO2–-containing NH4+-deprived medium. This blue-light- dependent recovery, which took 1 h, could be suppressed by cycloheximide, indicating that protein biosynthesis was involved. The biosynthesis of nitrite reductase took place in cell suspensions irradiated with red light, even in the absence of NO2–, thus suggesting that the process requiring blue light was the biosynthesis of an NO2– transport system. Nitrite reductase-containing cells (pre-irradiated with red light) took 1 h to start consuming NO2– when they were additionally irradiated with blue light in the presence of this anion, and this process was also cycloheximide-sensitive. The NO2– transport system operated either under red plus blue light or red light only. Thus, in C. reinhardtii mutant S10 cells, blue light was only required for the biosynthesis of an NO2– transport system and not for its activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3040.1999.00480.x
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Characterization of the blue light-induced extracellular alkalinization associated with the monovalent anion uptake by Monorapidium braunii. Competition between NO3 and Cl− (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 94 (1995), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The blue light-elicited monovalent anion-dependent alkalinization of the medium of Monoraphidium braunü (Legnerová, 202–7d) was characterized for the NO-3 and Cl- uptake. The maximal H+ uptake rates for these two anions have a similar optimum pH around 8.5, and quite similar Ks values for high (38 üM for Cl- and 35üM for NO-3) and low (320 üM for Cl- and 335 üM for NO-3) affinities. The steady H+ uptake associated with the uptake and reduction of NO-3 showed a Ks of 125 üM. which in this alga corresponds to the NO-3 reductase (EC 1.6.6.2) Km for NO-3. The only and striking difference found in the uptake properties of these anions was the delay time between the switching on of the blue light and the start of the alkalinization, which increased from 10 to 90 s as the initial pH decreased from 8.5 to 6.5 in the presence of NO-3, whereas for Cl- uptake this delay time (10s) did not vary in relation to the initial pH. When the NO-3 concentration in the medium was low (100 üM), the presence of relatively high concentrations of Cl- (3 üM), on the one hand, greatly stimulated the maximal alkalinization rates but, on the other, Cl- severely reduced the steady NO-3-dependent rate of alkalinization. The data indicate that Cl- inhibits competitively NO-3 uptake with a Ki of 750 üM. Moreover, high concentrations of NO-3 (above 5 üM) reduced its own maximal, but not the steady, uptake rates. The above results allow us to propose that most of the components of the individual NO-3 and Cl- transport systems are under identical light control and, as the competition data suggest, that these two anions may be taken up by the same transport system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1995.tb00966.x
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  • 4
    Electronic Resource
    Electronic Resource
    Blue light-dependent monovalent anion uptake (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 100 (1997), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Blue light is one of the most important environmental signals regulating monovalent anion transport in plant cells. In the unicellular freshwater chlorophyte Monoraphidium braunii, blue light is essential for the activation of HCO3−, NO3−, NO22 and Cl− transport systems. These anions are taken up when blue light is present but the uptake ceases when this radiation is suppressed, indicating that blue light is a switch signal for the monovalent anion transport system(s) of this alga. Similar results have been obtained in other green algae and higher plants. The action spectra for the uptake of NO3− and Cl− in M. braunii are very similar and resemble the absorption spectra of flavins or a combination of flavins and pterins. It is proposed that both anions share the same transport system(s). The uptake of monovalent anions consists of a cotransport with H+, thus producing alkalinization of the external medium. The time between the onset of blue light and the beginning of alkalinization can be as short as 2 s. Taken together, the results suggest that the photoreceptor mediating the blue light activation of monovalent anion uptake in this green alga is a plasma membrane-bound flavoprotein.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1997.tb03453.x
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Blue-light reactivation of spinach nitrate reductase inactivated by acetylene or cyanide. Effects of flavins and oxygen (1983)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 57 (1983), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Nitrate reductase (NADH: nitrate oxidoreductase, EC 1.6.6.1) of spinach (Spinacia oleracea L.) leaves, inactivated in vitro by acetylene, was reactivated by irradiation with blue light. Red + infrared, green or white light of the same irradiance were less effective. The dehydrogenase activity of the nitrate reductase complex was not required for pliotoreactivation. Photoreactivation of cyanide-inactivated nitrate reductase was greatly enhanced by the addition of 1 and 20 μ of either FMN or FAD; however, flavins showed a much smaller stimulatory effect on photoreactivation of acetylene-inactivated enzyme. The effect of flavins was higher under anaerobic conditions. This might imply the direct ievolvement of excited flavins in the photoreactivation mechanism. Besides promoting photoreactivation, blue light irradiation led simultaneously to a gradual inactivation of the enzyme especially under air and 20 μ FMN, eventually abolishing the recovered activity of the enzyme.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1983.tb02761.x
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Photoinactivation of the detoxifying enzyme nitrophenol reductase from Rhodobacter capsulatus (1995)
    Springer
    Archives of microbiology 163 (1995), S. 248-253 
    Details
    ISSN: 1432-072X
    Keywords: Key words Dinitrophenol biodegradation ; Photoinactivation ; Blue light ; Flavoprotein ; Rhodobacter capsulatus ; Triplet flavin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The phototrophic bacterium Rhodobacter capsulatus E1F1 detoxifies 2,4-dinitrophenol by inducing an NAD(P)H-dependent iron flavoprotein that reduces this compound to the less toxic end product 2-amino-4-nitrophenol. This nitrophenol reductase was stable in crude extracts containing carotenes, but it became rapidly inactivated when purified protein was exposed to intense white light or moderate blue light intensities, especially in the presence of exogenous flavins. Red light irradiation had no effect on nitrophenol reductase activity. Photoinactivation of the enzyme was irreversible and increased under anoxic conditions. This photoinactivation was prevented by reductants such as NAD(P)H and EDTA and by the excited flavin quencher iodide. Addition of superoxide dismutase, catalase, tryptophan or histidine did not affect photoinactivation of nitrophenol reductase, thus excluding these reactive dioxygen species as the inactivating agent. Substantial protection by 2,4-dinitrophenol also took place when the enzyme was irradiated at a wavelength coinciding with one of the absorption peaks of this compound (365 nm). These results suggest that the lability of nitrophenol reductase was due to the absorption of blue light by the flavin prosthetic group, thus producing an excited flavin that might irreversibly oxidize some functional group(s) necessary for enzyme catalysis. Nitrophenol reductase may be preserved in vivo from blue light photoinactivation by the high content of carotenes and excess of reducing equivalents in phototrophic growing cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00393376
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  • 7
    Electronic Resource
    Electronic Resource
    Photoinactivation of the detoxifying enzyme nitrophenol reductase from Rhodobacter capsulatus (1995)
    Springer
    Archives of microbiology 163 (1995), S. 248-253 
    Details
    ISSN: 1432-072X
    Keywords: Dinitrophenol biodegradation ; Photoinactivation ; Blue light ; Flavoprotein ; Rhodobacter capsulatus ; Triplet flavin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The phototrophic bacterium Rhodobacter capsulatus E1F1 detoxifies 2,4-dinitrophenol by inducing an NAD(P)H-dependent iron flavoprotein that reduces this compound to the less toxic end product 2-amino-4-nitrophenol. This nitrophenol reductase was stable in crude extracts containing carotenes, but it became rapidly inactivated when purified protein was exposed to intense white light or moderate blue light intensities, especially in the presence of exogenous flavins. Red light irradiation had no effect on nitrophenol reductase activity. Photoinactivation of the enzyme was irreversible and increased under anoxic conditions. This photoinactivation was prevented by reductants such as NAD(P)H and EDTA and by the excited flavin quencher iodide. Addition of superoxide dismutase, catalase, tryptophan or histidine did not affect photoinactivation of nitrophenol reductase, thus excluding these reactive dioxygen species as the inactivating agent. Substantial protection by 2,4-dinitrophenol also took place when the enzyme was irradiated at a wavelength coinciding with one of the absorption peaks of this compound (365nm). These results suggest that the lability of nitrophenol reductase was due to the absorption of blue light by the flavin prosthetic group, thus producing an excited flavin that might irreversibly oxidize some functional group(s) necessary for enzyme catalysis. Nitrophenol reductase may be preserved in vivo from blue light photoinactivation by the high content of carotenes and excess of reducing equivalents in phototrophic growing cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00393376
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    Paper (German National Licenses)
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  • 8
    Electronic Resource
    Electronic Resource
    Effects of light quality, CO2 tensions and NO 3 +− concentrations on the inorganic nitrogen metabolism of Chlamydomonas reinhardii (1984)
    Springer
    Photosynthesis research 5 (1984), S. 97-103 
    Details
    ISSN: 1573-5079
    Keywords: Chlamydomonas reinhardii ; nitrate reductase ; inorganic nitrogen metabolism ; carbon metabolism ; blue light ; photochromic regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The blue light dependent utilization of nitrate by green algae under common air and high irradiances, besides its assimilatory nature, is associated with the release of NO2 − and NH4 + to the culture medium. If the CO2 content of the sparging air was increased up to 2%, previously excreted NO2 − and NH4 + were rapidly assimilated. When under air and high irradiances the cell density in the culture reached values corresponding to 25 μg Ch 1.ml-1, no further growth was observed and the highest values of NO3 − consumption and NO2 − and NH4 + release were attained. Besides low CO2 tensions, increasing NO3 − concentrations in the medium stimulated the release of NO3 − and NH4 +. Under CO2-free air the consumption of NO3 − and the release of NO2 − and NH4 + on a total N bases were almost stoichiometric and their rates saturated at much lower irradiances than under air. Under CO2-free air high rates of NO2 − release were only observed under the blue radiations that were effectively absorbed by photosynthetically active pigments, i.e. 460 nm, but not under 404 and 630 nm radiations. However, the simultaneous illumination of the cells with 404 and 630 nm monochromatic light showed a remarkable synergistic effect on NO2 − release. The results are discussed in terms of the close relationship between C and N metabolism, the photosynthetic reducing power required to convert NO inf3 sup± -N into R − NH2-N and the blue light activation of nitrate reductase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00028523
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