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  • 1
    Electronic Resource
    Electronic Resource
    Further characterization of the psbH locus of Synechocystis sp. PCC 6803: Inactivation of psbH impairs QA to QB electron transport in photosystem 2 (1993)
    s.l. : American Chemical Society
    Biochemistry 32 (1993), S. 1454-1465 
    Details
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/bi00057a008
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  • 2
    Electronic Resource
    Electronic Resource
    Singlet oxygen imaging in Arabidopsis thaliana leaves under photoinhibition by excess photosynthetically active radiation (2001)
    Copenhagen : Munksgaard International Publishers
    Physiologia plantarum 112 (2001), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Arabidopsis thaliana leaves were infiltrated with DanePy (3-(N-diethylaminoethyl)-N-dansyl)aminomethyl-2,5-dihydro-2,2,5,5-tetramethyl-1H-pyrrole), a double, fluorescent and spin sensor of singlet oxygen. DanePy fluorescence was imaged by laser scanning microscopy. We found that DanePy penetrated into chloroplasts but did not alter the functioning of the photosynthetic electron transport as assessed by chlorophyll fluorescence induction. In imaging, DanePy fluorescence was well distinct from chlorophyll fluorescence. Photoinhibition by excess photosynthetically active radiation caused quenching of DanePy fluorescence in the chloroplasts but not in other cell compartments. When leaves were infiltrated with dansyl, the fluorescent group in DanePy, there was no fluorescence quenching during photoinhibition. This shows that the fluorescence quenching of DanePy is caused by the conversion of its pyrrol group into nitroxide, i.e. it was caused by the reaction of singlet oxygen with the double sensor and not by artifacts. These data provide direct experimental evidence for the localization of singlet oxygen production to chloroplasts in vivo.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1399-3054.2001.1120102.x
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  • 3
    Electronic Resource
    Electronic Resource
    Ultraweak light emission, free radicals, chilling and light sensitivity (1996)
    Copenhagen : Munksgaard International Publishers
    Physiologia plantarum 98 (1996), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Ultraweak light emission (UWLE) was measured from leaves of various chilling-sensitive (Lycopersicon esculentum, Cucumis sativus and Phaseolus vulgaris) and -tolerant (Pisum sativum and Vicia faba) plants after exposure to low (4-7°C) temperature in the light. UWLE increased upon chilling treatment combined with illumination with 200 µmol m−2 s−1 PAR in all plants, by about 30% in tolerant and by more than 100% in sensitive plants. It increased more when applied together with 400 µmol m−2 s−1 PAR: by 90-100% and by 250-280% in chilling-tolerant and -sensitive plants, respectively. Free radical production was detected by spin-trapping EPR spectroscopy in thylakoid membranes isolated from the chilling-treated Lycopersicon esculentum and Vicia faba leaves. After 12 h chilling at 200 µmol m−2 s−1 PAR, free radical production was approximately 3 times greater in the former than in the latter species. The same ratio was approximately 6 if chilling was carried out at 400 µmol m−2 s−1 PAR, indicating the role of photooxidative stress in chilling injury.Our results also confirm that the stress-induced increase in UWLE is an indicator of free radical production and offers the possibility of using UWLE for monitoring the effect of chilling on temperature-sensitive plants in an early stage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1399-3054.1996.980201.x
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  • 4
    Electronic Resource
    Electronic Resource
    Triazine-resistant Nicotiana mutants from photomixotrophic cell cultures (1985)
    Springer
    Molecular genetics and genomics 200 (1985), S. 508-510 
    Details
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Triazine-resistant mutants have been isolated in photomixotrophic cell cultures of Nicotiana plumbaginifolia. Triazine herbicides inhibit photosynthesis and cause extensive photodestruction of chloroplasts (bleaching) in sensitive plants. Selection was based on the greening ability of the resistant cells in the presence of 10-4 M terbutryn, under normal culture conditions, but in a medium containing a low sugar concentration. In the mutant plants, as compared to wild type, two to three orders of magnitude higher concentrations of triazines resulted in inhibition of photosynthetic electron transport and greening. The resistance was inherited maternally.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00425742
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  • 5
    Electronic Resource
    Electronic Resource
    The role of phospholipids in regulating photosynthetic electron transport activities: Treatment of thylakoids with phospholipase C (1995)
    Springer
    Photosynthesis research 46 (1995), S. 287-293 
    Details
    ISSN: 1573-5079
    Keywords: fluorescence induction ; membrane lipids ; Photosystem II ; thermoluminescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The involvement of phospholipids in the regulation of photosynthetic electron transport activities was studied by incubating isolated pea thylakoids with phospholipase C to remove the head-group of phospholipid molecules. The treatment was effective in eliminating 40–50% of chloroplast phospholipids and resulted in a drastic decrease of photosynthetic electron transport. Measurements of whole electron transport (H2O→methylviologen) and Photosystem II activity (H2O→p-benzoquinone) demonstrated that the decrease of electron flow was due to the inactivation of Photosystem II centers. The variable part of fluorescence induction measured in the absence of electron acceptor was decreased by the progress of phospholipase C hydrolysis and part of the signal could be restored on addition of 3-(3′,4′-dicholorophenyl)-1,1-dimethylurea. The B and Q bands of thermoluminescence corresponding to S2S3QB − and S2S3QA − charge recombination, respectively, was also decreased with a concomitant increase of the C band, which originated from the tyrosine D+QA − charge recombination. These results suggest that phospholipid molecules play an important role in maintaining the membrane organization and thus maintaining the electron transport activity of Photosystem II complexes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00020442
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  • 6
    Electronic Resource
    Electronic Resource
    The far red induced slow component of delayed light from chloroplasts is emitted from Photosystem II (1991)
    Springer
    Photosynthesis research 29 (1991), S. 107-112 
    Details
    ISSN: 1573-5079
    Keywords: chloroplast ; delayed light emission ; emission spectrum ; far red irradiation ; Photosystem II ; spinach
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In spinach chloroplasts illuminated with far red light, the relative intensity maximum during the decay of delayed light is emitted at 680–690 nm. This finding supports previous models predicting emission from Photosystem II, and contradicts earlier attributions to Photosystem I. Due to self absorption, the emission spectrum of the relative maximum is shifted to longer wavelengths and displays apparent Photosystem I characteristics in chloroplast samples of higher concentration or in leaves. This may have caused earlier investigators to ascribe the emission to Photosystem I. A differences between the spectral width of the emission spectra of delayed fluorescence and the relative maximum indicates that these two phenomena represent emission from different sub-populations of Photosystem II centers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00035381
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  • 7
    Electronic Resource
    Electronic Resource
    Inactivation of photosynthetic oxygen evolution by UV-B irradiation: A thermoluminescence study (1993)
    Springer
    Photosynthesis research 38 (1993), S. 455-462 
    Details
    ISSN: 1573-5079
    Keywords: oxygen evolution ; photodamage ; Photosystem II ; thermoluminescence ; UV-B radiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The influence of UV-B irradiation on photosynthetic oxygen evolution by isolated spinach thylakoids has been investigated using thermoluminescence measurements. The thermoluminescence bands arising from the S2QB - (B band) and S2QA − (Q band) charge recombination disappeared with increasing UV-B irradiation time. In contrast, the C band at 50°C, arising from the recombination of QA - with an accessory donor of Photosystem II, was transiently enhanced by the UV-B irradiation. The efficiency of DCMU to block QA to QB electron transfer decreased after irradiation as detected by the incomplete suppression of the B band by DCMU. The flash-induced oscillatory pattern of the B band was modified in the UV-B irradiated samples, indicating a decrease in the number of centers with reduced QB. Based on the results of this study, UV-B irradiation is suggested to damage both the donor and acceptor sides of Photosystem II. The damage of the water-oxidizing complex does not affect a specific S-state transition. Instead, charge stabilization is enhanced on an accessory donor. The acceptor-side modifications decrease the affinity of DCMU binding. This effect is assumed to reflect a structural change in the QB/DCMU binding site. The preferential loss of dark stable QB - may be related to the same structural change or could be caused by the specific destruction of reduced quinones by the UV-B light.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00046774
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  • 8
    Electronic Resource
    Electronic Resource
    Singlet oxygen production in thylakoid membranes during photoinhibition as detected by EPR spectroscopy (1994)
    Springer
    Photosynthesis research 39 (1994), S. 191-199 
    Details
    ISSN: 1573-5079
    Keywords: photoinhibition ; photosynthesis ; protein degradation ; singlet oxygen ; TEMP (2,2,6,6-tetramethylpiperidine) ; thylakoid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Exposure of isolated spinach thylakoids to high intensity illumination (photoinhibition) results in the well-characterized impairment of Photosystem II electron transport, followed by degradation of the D1 reaction centre protein. In the present study we demonstrate that this process is accompanied by singlet oxygen production. Singlet oxygen was detected by EPR spectroscopy, following the formation of stable nitroxide radicals from the trapping of singlet oxygen with a sterically hindered amine TEMP (2,2,6,6-tetramethylpiperidine). There was no detectable singlet oxygen production during anaerob photoinhibition or in the presence of sodium-azide. Comparing the kinetics of the loss of PS II function and D1 protein with that of singlet oxygen trapping suggests that singlet oxygen itself or its radical product initiates the degradation of D1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00029386
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  • 9
    Electronic Resource
    Electronic Resource
    Superoxide radicals are not the main promoters of acceptor-side-induced photoinhibitory damage in spinach thylakoids (1995)
    Springer
    Photosynthesis research 46 (1995), S. 399-407 
    Details
    ISSN: 1573-5079
    Keywords: thylakoid ; photoinhibition ; superoxide radical ; spin trapping ; DMPO ; Tiron
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Superoxide anion radical formation was studied with isolated spinach thylakoid membranes and oxygen evolving Photosystem II sub-thylakoid preparations using the reaction between superoxide and Tiron (1,2-dihydroxybenzene-3,5-disulphonate) which results in the formation of stable, EPR detectable Tiron radicals. We found that superoxide was produced by illuminated thylakoids but not by Photosystem II preparations. The amount of the radicals was about 70% greater under photoinhibitory conditions than under moderate light intensity. Superoxide production was inhibited by DCMU and enhanced 4–5 times by methyl viologen. These observations suggest that the superoxide in illuminated thylakoids is from the Mehler reaction occurring in Photosystem I, and its formation is not primarily due to electron transport modifications brought about by photoinhibition. Artificial generation of superoxide from riboflavin accelerated slightly the photoinduced degradation of the Photosystem II reaction centre protein D1 but did not accelerate the loss of oxygen evolution supported by a Photosystem II electron acceptor. However, analysis of the protein breakdown products demonstrated that this added superoxide did not increase the amount of fragments brought about by photoinhibition but introduced an additional pathway of damage. On the basis of the above observations we propose that superoxide redicals are not the main promoters of acceptor-side-induced photoinhibition of Photosystem II.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00032294
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  • 10
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    UV-B exposure, ROS, and stress: inseparable companions or loosely linked associates? (2013)
    Cell Press
    Details
    Publication Date: 2013-02-01
    Print ISSN: 1360-1385
    Electronic ISSN: 1878-4372
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Cell Press
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