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  • 1
    Electronic Resource
    Electronic Resource
    The relationship between state II to state I transitions and cyclic electron flow around photosystem I (1983)
    Springer
    Photosynthesis research 4 (1983), S. 245-256 
    Details
    ISSN: 1573-5079
    Keywords: State I-state II transitions ; blue-green alga ; cyanobacterium ; photosynthesis ; energy transfer ; cyclic electron flow ; phase transitions ; Synechococcus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of electron acceptors, inhibitors of electron flow and uncouplers and inhibitors of photophosphorylation on a state II to I transition were studied. 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) did not inhibit the state II to I transition. By contrast, 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone (DBMIB), methyl viologen and antimycin A inhibited the transition indicating that the cyclic electron flow around photosystem I, but not the oxidation of electron carriers (such as plastoquinone), induced the state II to I transition. Uncouplers, but not inhibitors of photophosphorylation, inhibited the state transition suggesting that the proton transport through the cyclic electron flow was related to the transition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00052128
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  • 2
    Electronic Resource
    Electronic Resource
    Effects of high temperatures on the photosynthetic systems in spinach: Oxygen-evolving activities, fluorescence characteristics and the denaturation process (1998)
    Springer
    Photosynthesis research 57 (1998), S. 51-59 
    Details
    ISSN: 1573-5079
    Keywords: chlorophyll fluorescence ; high-temperature stress ; O2 evolution ; photosynthesis ; Photosystem II ; spinach
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Activities of oxygen evolution, fluorescence Fv (a variable part of chlorophyll fluorescence) values, and amounts of the 33 kDa protein remaining bound to the thylakoids in intact spinach chloroplasts were measured during and after high-temperature treatment. The following results were obtained. (1) Both the Fv value and the flash-induced oxygen evolution measured by an oxygen electrode were decreased at high temperatures, but they showed partial recovery when the samples were cooled down and incubated at 25°C for 5 min after high-temperature treatment. (2) Oxygen evolution was more sensitive to high temperatures than the Fv value, and the decrease in the Fv/Fm ratio at high temperatures rather corresponded to that in the oxygen evolution measured at 25°C after high-temperature treatment. (3) Photoinactivation of PS II was very rapid at high temperatures, and this seems to be a cause of the difference between the Fv values and the oxygen-evolving activities at high temperatures. (4) At around 40°C, the manganese-stabilizing 33 kDa protein of PS II was supposed to be released from the PS II core complexes during heat treatment and to rebind to the complexes when the samples were cooled down to 25°C. (5) At higher temperatures, the charge separation reaction of PS II was inactivated, and the PS II complexes became less fluorescent, which was recovered partially at 25°C. (6) Increases in the Fv value due to a large decrease in the electron flow from QA to QB became prominent after high-temperature treatment at around 50°C. This was the main cause of the discrepancy between the Fv values and the oxygen-evolving activities measured at 25°C. Relationship between the process of heat inactivation of PS II reaction center complexes and the fluorescence levels is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006019102619
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  • 3
    Electronic Resource
    Electronic Resource
    15-Cis-carotenoids found in the reaction center of a green sulfur bacterium Chlorobium tepidum and in the Photosystem I reaction center of a cyanobacterium Synechococcus vulcanus (1998)
    Springer
    Photosynthesis research 58 (1998), S. 135-142 
    Details
    ISSN: 1573-5079
    Keywords: carotenoids ; 15-cis configuration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Carotenoids were extracted, at ∼4 °C in complete darkness and under nitrogen atmosphere, from the reaction center (RC) of a green-sulfur bacterium and the Photosystem (PS) I RC of a cyanobacterium; each extract was subjected to high-performance liquid chromatography (HPLC) using an apparatus equipped with a two-dimensional diode-array detector in order to spectroscopically identify cis–trans carotenoids while performing HPLC analysis. In the extract from the RC of Chlorobium tepidum, 15-cis and all-trans-γ-carotenes as well as 13-cis-, 15-cis- and all- trans-chlorobactenes (in the order of elution) were identified, whereas in the extract from the PS I RC of Synechococcus vulcanus, 15-cis-, all-trans- and 9-cis-β-carotenes were found. Thus, the universal presence of 15- cis carotenoids in the 'iron sulfur-type' RCs has been shown in addition to the previous cases of the 'quinone-type' RCs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006112323144
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  • 4
    Electronic Resource
    Electronic Resource
    Increases in the fluorescence Fo level and reversible inhibition of Photosystem II reaction center by high-temperature treatments in higher plants (1997)
    Springer
    Photosynthesis research 52 (1997), S. 57-64 
    Details
    ISSN: 1573-5079
    Keywords: Fm ; high-temperature stress ; pheophytin a ; photosynthesis ; Qa ; spinach
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Effects of high temperatures on the fluorescence Fm (maximum fluorescence) and Fo (dark level fluorescence) levels were studied and compared with those of the photochemical reactions of PS II. These comparisons were performed during and after the high temperature treatments. The following results were obtained; (1) increases in the Fo level at high temperatures were partly reversible, (2) the Fm level in the presence of dithionite in spinach chloroplasts decreased at high temperatures and also showed a partial reversibility, (3) photoreductions of pheophytin a and Qa were reversibly inhibited at high temperatures parallel to the decrease in the difference between the Fm and Fo levels, and (4) the decrease in the fluorescence Fm level seemed to be related to denaturation of chlorophyll-proteins. All the data suggested that, as well as the separation of light-harvesting chlorophyll a/t b protein complexes of PS II from the PS II core complexes, partly reversible inactivation of the PS II reaction center at high temperatures is the cause of the increase in the Fo level.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005884717655
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  • 5
    Electronic Resource
    Electronic Resource
    Reduction of QA in the dark: Another cause of fluorescence Fo increases by high temperatures in higher plants (2000)
    Springer
    Photosynthesis research 63 (2000), S. 23-34 
    Details
    ISSN: 1573-5079
    Keywords: chlororespiration ; pheophytin a ; photosynthesis ; Photosystem II ; potato ; tobacco
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Increases in the chlorophyll fluorescence Fo (dark level fluorescence) during heat treatments were studied in various higher plants. Besides the dissociation of light-harvesting chlorophyll a/b protein complexes from the reaction center complex of PS II and inactivation of PS II, dark reduction of QA via plastoquinone (PQ) seemed to be related to the Fo increase at high temperatures. In potato leaves or green tobacco cultured cells, a part of the Fo increase was quenched by light, reflecting light-induced oxidation of QA - which had been reduced in the dark at high temperatures. Appearance of the Fo increase due to QA reduction depended on the plant species, and the mechanisms for this are proposed. The reductants seemed to be already present and formed by very brief illumination of the leaves at high temperatures. A ndhB-less mutant of tobacco showed that complex I type NAD(P)H dehydrogenase is not involved in the heat-induced reduction of QA. Quite strong inhibition of the QA reduction by diphenyleneiodonium suggests that a flavoenzyme is one of the electron mediator to PQ from the reductant in the stroma. Reversibility of the heat-induced QA reduction suggests that an enzyme(s) involved is activated at high temperatures and mostly returns to an inactive form at room temperature (25 °C).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006350706802
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  • 6
    Electronic Resource
    Electronic Resource
    Identification of Photosystem I components from a glaucocystophyte, Cyanophora paradoxa: The PsaD protein has an N-terminal stretch homologous to higher plants (2000)
    Springer
    Photosynthesis research 65 (2000), S. 207-217 
    Details
    ISSN: 1573-5079
    Keywords: Cyanophora paradoxa ; glaucocystophyte ; light harvesting complex ; Photosystem I ; PsaD ; PsaL
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Thylakoid membranes and Photosystem I (PS I) complexes were isolated from a glaucocystophyte, Cyanophora paradoxa, which is thought to have the most primitive ‘plastids’, and the proteins related to PS I were examined. The intrinsic light-harvesting chlorophyll protein complexes of PS I (LHC I) were not detected by an immunological method. The PS I complexes consisted of at least eight low-molecular-mass proteins in addition to PS I reaction center proteins. The N-terminal sequence of the PsaD protein has higher homology to that of Chlamydomonas reinhardtii and land plants, than to that of other algae or cyanobacteria. On the other hand, the PsaL sequence has the highest homology to those of cyanobacteria. Taking into account the other sequences of PS I components whose genes are encoded in the cyanelle genome, and the fact that LHC I is not detected, it is concluded that PS I of C. paradoxa has chimeric characteristics of both ‘green’ lineages and cyanobacteria.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1010734912776
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  • 7
    Electronic Resource
    Electronic Resource
    Plastoquinone as a common link between photosynthesis and respiration in a blue-green alga (1980)
    Springer
    Photosynthesis research 1 (1980), S. 149-162 
    Details
    ISSN: 1573-5079
    Keywords: blue-green algae ; cytochrome 553 ; electron transport ; photosynthesis ; plastoquinone ; respiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The role of plastoquinone in a thermophilic blue-green alga, Shynechococcus sp., was studied by measuring reduction kinetics of cytochrome 553 which was oxidized with red flash preferentially exciting photosystem I. Sensitivity of the cytochrome reduction to DBMIB Abbreviations: DCMU = 3-(3,4-dichlorophenyl)-1,1-dimethylurea; DBMIB = 2,5-dib romo-3-methyl-6-isopropyl-p-benzoquinone; HOQNO = 2-n-heptyl-4-hydroxyquinoline-N-oxide indicates that cytochrome 553 accepts electrons from reduced plastoquinone. Plastoquinone is in turn reduced in cells without electrons from photosystem II, since DCMU Abbreviations: DCMU = 3-(3,4-dichlorophenyl)-1,1-dimethylurea; DBMIB = 2,5-dib romo-3-methyl-6-isopropyl-p-benzoquinone; HOQNO = 2-n-heptyl-4-hydroxyquinoline-N-oxide , which inhibited methyl viologen photoreduction more strongly than DBMIB, failed to affect the cytochrome reduction. Participation of cyclic electron transport around photosystem I in cytochrome reduction in the presence of DCMU was excluded, because methyl viologen and antimycin A had no effect on the cytochrome kinetics. On the other hand, electron donation from endogenous substrates to plastoquinone was suggested from decreases in rate of the cytochrome reduction by dark starvation of cells and also from restoration of fast reduction kinetics by the addition of exogenous substrates to or by reillumination of starved cells. KCN, which completely suppressed respiratory O2-uptake, induced a marked acceleration of the cytochrome reduction in starved cells. The poison was less or not effective in stimulating the cytochrome reduction in more extensively starved or reilluminated cells. Results indicate that plastoquinone is functioning not only in the photosynthetic but also in the respiratory electron transport chain, thereby forming a common link between the two energy conservation systems of the blue-green alga.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00020594
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  • 8
    Electronic Resource
    Electronic Resource
    Changes in the distribution of light energy between the two photosystems in spinach leaves (1983)
    Springer
    Photosynthesis research 4 (1983), S. 71-79 
    Details
    ISSN: 1573-5079
    Keywords: Chlorophyll fluorescence ; energy transfer ; fluorescence emission spectra ; spinach leaves ; state I-state II transitions ; the Kautsky effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Time courses of chlorophyll fluorescence at room temperature and fluorescence spectra at 77 K were measured to investigate the light-induced changes in the distribution of light energy between the two photosy stems in young spinach leaves. Illumination of the dark adapted leaves with primarily system II light induced typical fluorescence transients at room temperature. Fluorescence spectra at 77 K showed that the intensity of system II fluorescence at 77 K changed nearly in parallel with the fluorescence transients at room temperature within the range from M1 to T during illumination of the leaf. Illumination of the dark adapted leaves with light I produced an increase of system II fluorescence measured at 77 K. The characteristics of the changes induced by light I or II were different, showing that these two effects are related to different mechanisms. These results suggest that the dark state in spinach leaves is state II, that light I induces a state II to I transition, while light II induces fluorescence changes that are produced by mechanisms other than state I-state II transitions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00041802
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  • 9
    Electronic Resource
    Electronic Resource
    The relationship between state II to state I transitions and cyclic electron flow around photosystem I (1983)
    Springer
    Photosynthesis research 4 (1983), S. 245-256 
    Details
    ISSN: 1573-5079
    Keywords: State I-state II transitions ; blue-green alga ; cyanobacterium ; photosynthesis ; energy transfer ; cyclie electron flow ; phase transitions ; Synechococcus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of electron acceptors, inhibitors of electron flow and uncouplers and inhibitors of photophosphorylation on a state II to I transition were studied. 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) did not inhibit the state II to I transition. By contrast, 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone (DBMIB), methyl viologen and antimycin A inhibited the transition indicating that the cyclic electron flow around photosystem I, but not the oxidation of electron carriers (such as plastoquinone), induced the state II to I transition. Uncouplers, but not inhibitors of photophosphorylation, inhibited the state transition suggesting that the proton transport through the cyclic electron flow was related to the transition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00041820
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  • 10
    Electronic Resource
    Electronic Resource
    A new mechanism for adaptation to changes in light intensity and quality in the red alga, Porphyra perforata. II. Characteristics of state II—state III transitions (1983)
    Springer
    Photosynthesis research 4 (1983), S. 61-70 
    Details
    ISSN: 1573-5079
    Keywords: chlorophyll fluorescence ; energy transfer ; Parphyra perforata ; red algae ; state I—state II transitions ; state II—state III transitions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Characteristics of state II—state III transitions in the red alga, Porphyra perforata, were studied by measuring the fluorescence time course at room temperature and fluorescence spectra at 77 K. The state II to III transition was induced by system II light and was sensitive to uncouplers of photophosphorylation. This state II to III transition has a dark step(s) that could be easily separated from the light process. A state III to II transition occurred in the dark, but system I light accelerated the transition. The accelerating effect of system I light was not sensitive to uncouplers of photophosphorylation, but was inhibited by the addition of valinomycin + KCl or antimycin A. Compared to state I—state II transitions, the state II—state III transitions occurred more rapidly. The state II to state III transitions are different from the state I to state II transitions in that in state III the activity of photosystem II is changed without having any effect on photosystem I activity (Satoh and Fork, Biochim. Biophys, Acta, in press, 1982). It is suggested that the state II—state III transition represents a mechanism by which the alga can avoid photodamage resulting from absorption of excess light energy by photosystem II.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00041801
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