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21Author    V. Ictor, B. Curw, G. Ert, S. Chan Sk Er, O. Scar, J. De, V. Os, J. S. Van RensenRequires cookie*
 Title    Comparison of Photosynthetic Activities in Triazine-Resistant and Susceptible Biotypes of Chenopodium album  
 Abstract    Triazine-resistant and susceptible Chenopodium album plants were grown at low and at high light irradiances. A t the lower light irradiance the dry m atter production of the resistant and the susceptible plants were almost similar. At the higher irradiance the resistant biotype had a significantly lower production. Fluorescence studies showed that the photochemical yield and the photosystem II electron transport rate were lower in the resistant biotype. It could be demonstrated in intact leaves that the lower productivity of the resistant biotype is caused by a higher sensitivity to photoinhibition. However, when studying effects of photoinhibition on electron flow and photophosphorylation in isolated thylakoids o f the two biotypes, no signifi­ cant differences between resistant and susceptible plant materials were observed. It is suggest­ ed that the difference between resistant and susceptible biotypes connected with processes pro­ tective against photoinhibition in intact leaves, are lost during the isolation of thylakoids. 
  Reference    Z. Naturforsch. 48c, 278 (1993); received November 26 1992 
  Published    1993 
  Keywords    Chloroplasts, Triazine-Resistance, Photosystem II, Photoinhibition, Fluorescence 
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 TEI-XML for    default:Reihe_C/48/ZNC-1993-48c-0278.pdf 
 Identifier    ZNC-1993-48c-0278 
 Volume    48 
22Author    U. Hegde, S. Padhye, L. Kovács, A. Vozár, S. DemeterRequires cookie*
 Title    Modification of Histidine Residues of Photosystem II by Diethyl Pyrocarbonate Inhibits the Electron Transfer between the Primary (QA) and Secondary (QB) Quinone Acceptors  
 Abstract    The effect o f diethyl pyrocarbonate (D EPC) on the photosynthetic electron transport was investigated in isolated spinach thylakoids by partial electron transport rate and thermolumi­ nescence measurements. Incubation o f thylakoids at pH 6.5 with 5 mM DEPC for 15 min re­ sulted in a considerable inhibition o f electron transport from water to dichlorophenolindo-phenol. The inhibition was only partially releaved by addition o f the donor, diphenylcarbazide indicating the effect o f DEPC both on the donor and acceptor sides o f PS II. In the thermolu­ minescence glow curve DEPC-treatm ent abolished the B band (S2Q B~ radiative charge recom ­ bination) at 30 °C with a concom itant appearance o f the Q band (S2QA~ charge recombina­ tion) at 10 °C. This suggests that in isolated thylakoids possessing an active water-splitting sys­ tem DEPC affects the electron transfer from QA to QB but does not inhibit the electron transport from manganese to QA during the S t—>S2 transition o f the water-splitting system. At the acceptor side o f PS II the targets o f DEPC are probably the histidines which are coordinat­ ed to the non-hem e iron. Illumination o f thylakoids at -8 0 °C following DEPC addition after two preflashes at 5 °C resulted in the replacement o f the A (A T) thermoluminescence band at -3 0 °C with a band appearing at -1 5 °C. This observation can be explained by the effect o f DEPC on a donor side histidine com ponent participating in the generation o f the A (A T) band. Consequently, in the interpretation o f results obtained by DEPC treatment o f PS II, both the donor and acceptor side effects o f DEPC should be considered. 
  Reference    Z. Naturforsch. 48c, 896—9 (1993); received May 4/September 6 1993 
  Published    1993 
  Keywords    Diethyl Pyrocarbonate, Histidine, Photosynthesis, Photosystem II, Thermoluminescence 
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 TEI-XML for    default:Reihe_C/48/ZNC-1993-48c-0896.pdf 
 Identifier    ZNC-1993-48c-0896 
 Volume    48 
23Author    Éva Hideg, Sándor DemeterRequires cookie*
 Title    Thermoluminescence and Delayed Luminescence Characterization of Photosystem II a and Photosystem II p Reaction Centers  
 Abstract    The thermoluminescence and delayed luminescence characteristics of PS II" and PS IIp centers were investigated in BBY particles and stroma thylakoids, respectively. The BBY particles exhib-ited a thermoluminescence band at 25 °C (B band) which was associated with the charge recombi-nation of the S 2 Qb" redox couple and underwent period-2 oscillation in a sequence of flashes. In the flash-induced decay of delayed luminescence of BBY particles a component with a half-time of 34 s corresponded to the B thermoluminescence band and was also assigned to S2OB charge recombination. No corresponding thermoluminescence or delayed luminescence components as-sociated with the secondary acceptor OB could be observed in the glow curve or delayed lumines-cence decay of stroma thylakoids. These observations indicate that unlike PS IIa the PS Hp centers are not associated with the two-electron gate, 0B. 
  Reference    Z. Naturforsch. 43c, 596—600 (1988); received May 2 1988 
  Published    1988 
  Keywords    Photosynthesis, Photosystem II, Thermoluminescence, Delayed Luminescence 
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 TEI-XML for    default:Reihe_C/43/ZNC-1988-43c-0596.pdf 
 Identifier    ZNC-1988-43c-0596 
 Volume    43 
24Author    SeymourSteven BrodyRequires cookie*
 Title    Rebinding of the 33 kDalton Polypeptide of Photosystem II to the D-l/D-2 Sub-Core Complex  
 Abstract    Specific and stoichiometric binding is shown between the D-l/D-2 sub-core complex and the 33 kDa polypeptide of photosystem II. Fluorescence from chlorophyll is used as an endogenous probe. When binding occurs there is an increase in fluorescence yield, as well as changes in both the fluorescence spectrum and excitation spectrum. 
  Reference    Z. Naturforsch. 43c, 727—730 (1988); received January 28/May 31 1988 
  Published    1988 
  Keywords    Photosynthesis, Reaction Center, Photosystem II, Chlorophyll, Fluorescence 
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 TEI-XML for    default:Reihe_C/43/ZNC-1988-43c-0727.pdf 
 Identifier    ZNC-1988-43c-0727 
 Volume    43 
25Author    Imre Vass, Narendranath Mohanty, Sándor DemeterRequires cookie*
 Title    Photoinhibition of Electron Transport Activity of Photosystem II in Isolated Thylakoids Studied by Thermoluminescence and Delayed Luminescence  
 Abstract    The effect of photoinhibition on the primary (Oa) and secondary (Ob) quinone acceptors of photosystem II was investigated in isolated spinach thylakoids by the methods of thermolumines-cence and delayed luminescence. The amplitudes of the Q (at about 2 °C) and B (at about 30 °C) thermoluminescence bands which are associated with the recombination of the S;OA and S2QB charge pairs, respectively, exhibited parallel decay courses during photoinhibitory treatment. Similarly, the amplitudes of the flash-induced delayed luminescence components ascribed to the recombination of S 2 0A and S 2 OB charge pairs and having half life-times of about 3 s and 30 s, respectively, declined in parallel with the amplitudes of the corresponding Q and B thermo-luminescence bands. The course of inhibition of thermoluminescence and delayed luminescence intensity was parallel with that of the rate of oxygen evolution. The peak positions of the B and Q thermoluminescence bands as well as the half life-times of the corresponding delayed lumines-cence components were not affected by photoinhibition. These results indicate that in isolated thylakoids neither the amount nor the stability of the reduced OB acceptor is preferentially decreased by photoinhibition. We conclude that either the primary target of photodamage is located before the Ob binding site in the reaction center of photosystem II or QA and OB undergo simultaneous damage. 
  Reference    Z. Naturforsch. 43c, 871—876 (1988); received August 12 1988 
  Published    1988 
  Keywords    Photosynthesis, Photoinhibition, Photosystem II, Thermoluminescence, Delayed Luminescence 
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 TEI-XML for    default:Reihe_C/43/ZNC-1988-43c-0871.pdf 
 Identifier    ZNC-1988-43c-0871 
 Volume    43 
26Author    John Bowyer1, Mark Hiltonb, Julian Whitelegge3, Philip Jewess6, Patrick Camillerib, Antony Croftsc, Howard RobinsoncRequires cookie*
 Title    Molecular Modelling Studies on the Binding of Phenylurea Inhibitors to the D 1 Protein of Photosystem II  
 Abstract    A hypothetical molecular model of part of the D 1 protein of photosystem II, based on the analogous portion of the L subunit of the Rhodopseudomonas viridis reaction centre, has been used to study the binding of an extended hydrophobic phenylurea inhibitor (N,N-dimethyl-carbamoyl)4 -amino-4 '-chloro-rra«5 -stilbene) (I) to the Q B site. The inhibitor was fitted by eye into a cleft in the site, and a limited part of the inhibitor/D 1 complex was energy minimized. The gross orientation of the inhibitor placed the dimethylurea moiety towards the predicted binding domain of the plastoquinone head group, and the stilbene moiety directed along the quinone isoprenoid side chain binding domain, suggesting a similar pathway of approach of the two molecules from the membrane into the binding site. Binding interactions of the inhibi­ tor included hydrogen bonds to the side chain hydroxyl of ser 264 and the peptide carbonyl group of ala 251, with the side chain hydroxyl of ser 268 as an alternative ligand. Numerous hydrophobic contacts were also possible. Although phenylureas do not bind to reaction centres of Rp. viridis, many of the binding interactions to D 1 could also be detected in Rp. viridis. However, the ß-CH2 and 5-C02-groups of glu 212 in Rp. viridis are located in the corresponding region of D 1 occupied by the dimethylurea moiety of the inhibitor in our model of its binding to D 1. This may explain why diuron (D C M U) does not bind to Rp. viridis reac­ tion centres. 
  Reference    Z. Naturforsch. 45c, 379—387 (1990); received November 23 1989 
  Published    1990 
  Keywords    Phenylureas, Photosystem II, D 1 Protein, Molecular Modelling 
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 TEI-XML for    default:Reihe_C/45/ZNC-1990-45c-0379.pdf 
 Identifier    ZNC-1990-45c-0379 
 Volume    45 
27Author    M. D. Arie-Jose, ElrieuRequires cookie*
 Title    The Effects of 3-(3,4-Dichlorophenyl)-l,l-dimethylurea on the Photosynthetic Oxygen Complex  
 Abstract    In the presence o f trypsin and ferricyanide as external electron acceptor, lettuce chloroplasts are resistant to DCM U, showing that the inhibitory site o f D C M U is only situated on the accep­ tor side o f photosystem II. However, kinetic properties o f the oxygen evolving com plex are m od i­ fied at non-saturating concentrations o f D C M U . These changes are interpreted in terms o f a model with two distinct charges separation systems on the sam e center: the auxiliary donor-acceptor system D Q L implicated in the transitions S| -» • S 2 and S2 -*■ S 3 would be m uch less affected by DCM U than the main donor-acceptor system Y Q H after the first flash. 
  Reference    Z. Naturforsch. 39c, 347—350 (1984); received N ovem ber 28 1983 
  Published    1984 
  Keywords    Herbicides, Oxygen Evolution, Photosystem II, Electron Acceptors, Electron D onors 
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 TEI-XML for    default:Reihe_C/39/ZNC-1984-39c-0347.pdf 
 Identifier    ZNC-1984-39c-0347 
 Volume    39 
28Author    J.M D Ucruet, P. G. Aillard, J. V. IenotRequires cookie*
 Title    Use of Chlorophyll Fluorescence Induction Kinetics to Study Translocation and Detoxication of DCMU-Type Herbicides in Plant Leaves  
 Abstract    Transient levels o f the fluorescence induction rise were used to quantify partial photosynthesis inhibition by DC M U -type herbicides in w hole leaves. Assays in different crop or weed species showed a good accuracy in measurements (generally, variation was lower than 5%). This technique was applied to the problem o f varietal selectivity o f wheat towards chlortoluron. 
  Reference    Z. Naturforsch. 39c, 354 (1984); received N ovem ber 15 1983 
  Published    1984 
  Keywords    Chlorophyll Fluorescence, Photosystem II, H erbicides Translocation, D etoxication 
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 TEI-XML for    default:Reihe_C/39/ZNC-1984-39c-0354.pdf 
 Identifier    ZNC-1984-39c-0354 
 Volume    39 
29Author    Z. NaturforschRequires cookie*
 Title    Redox-State Dependent Changes of Inhibitor-Binding to the Photosystem II Acceptor Complex  
 Abstract    Binding o f radioactively labelled D C M U , ioxynil and terbutryn to spinach chloroplasts is determined following preillum ination by single-turnover, saturating light flashes. W ith all o f the three herbicides binary oscillations o f binding are observed. D ark-adapted sam ples, or those pre­ illuminated by an even number o f flashes, bind more inhibitor than sam ples preillum inated by an odd number o f flashes. Binding oscillations depend on inhibitor incubation tim e and on the seasonal adaptation o f the plants. The binding kinetics follow ing a single flash display three phases, the last two o f which can be correlated with reoxidation kinetics o f the secondary p h oto­ system II acceptor Qb, as determined by fluorescence measurem ents. Analysis o f the binding at DCM U concentrations up to 10"7 M free D C M U yields identical binding constants for dark-and flash preilluminated samples, but much less binding sites follow ing one flash. It is concluded that up to 10~7 M free DCM U, centers with bound Q b do not contribute significantly to total binding. Displacement o f Q b from the binding site is half-saturated at about 10-6 M D C M U , as m onitored via fluorescence induction. The data are considered strong support for the Velthuys 'inhibitor-Q i competition model'. 
  Reference    Z. Naturforsch. 39c, 397 (1984); received D ecem ber 1 1983 
  Published    1984 
  Keywords    Inhibitor Binding, Photosystem II, Binary O scillation, Chlorophyll Fluorescence 
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 TEI-XML for    default:Reihe_C/39/ZNC-1984-39c-0397.pdf 
 Identifier    ZNC-1984-39c-0397 
 Volume    39 
30Author    K. Burda3-, K. Strzałkab, G. H. Schmid3Requires cookie*
 Title    Europium-and Dysprosium-Ions as Probes for the Study of Calcium Binding Sites in Photosystem II  
 Abstract    Trivalent lanthanide cations are suitable probes for C a2+-binding sites in photosystem II (PS II). PS II membranes prepared from Nicoticinci tabacum, intact and depleted of the extrinsic polypeptides were exposed to lanthanide ions (D y3+ and E u 3+). Small concen­ trations of dysprosium and europium ions enhance oxygen evolution under short saturating flashes. Higher concentrations of the rare earth cations cause the release of the three extrinsic peptides (17, 23 and 33 kDa) and reduce 0 2 yield. The reactivation of the PS II membranes, thus depleted of the 33 kDa subunit, by Ca2+ ions is not possible. Comparing E u 3+ with Dy3+ in this effect shows that E u 3+ is m ore effective than Dy3+, because a lower E u 3+-concentration in comparison to that of Dy3+ inactivates 0 2-evolution. The differences between europium and dysprosium can be explained by their different ionic radius. Our results suggest the existence of two Ca-binding regions: one with a low affinity for calcium would be located on the contact surface of the 23 and 33 kDa proteins and the second one with a high affinity, should be located close to the Mn-cluster and to tyrosine-161 (Z). The more tightly-bound calcium would be responsible for the activity of the PS II system. 
  Reference    Z. Naturforsch. 50c, 220 (1995); received O ctober 6/O ctob er 31 1994 
  Published    1995 
  Keywords    Calcium-Binding Sites, Photosystem II, Tobacco, Oxygen Evolution S-States 
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 TEI-XML for    default:Reihe_C/50/ZNC-1995-50c-0220.pdf 
 Identifier    ZNC-1995-50c-0220 
 Volume    50 
31Author    AchimE G Aua, HubertH. Tholeb, ElfriedeK. PistoriusaRequires cookie*
 Title    Isolation and Partial Characterization of a Manganese Requiring L-Arginine Metabolizing Enzyme Being Present in Photosystem II Complexes of Spinach and Tobacco  
 Abstract    A low L-arginine metabolizing enzyme (L -A M E) activity leading to ornithine, urea and additional products not identified so far could be detected in photosystem II (PS II) m em ­ branes of spinach and of the chlorophyll deficient tobacco mutant Su/su. The detectable L-AM E activity was very low in untreated PS II membranes, but increased significantly (about 10 fold) when the extrinsic peptides (psbO, P and Q gene products) were removed -suggesting that the L-AM E is exposed at the lumen side o f PS II. It was possible to isolate the detergent-solubilized protein from CaCl2-washed PS II membranes of spinach by a com ­ bination of anion and cation exchange columns. On the basis of SDS PAGE the protein was hom ogenous and had an apparent molecular mass of 7 kDa. N-terminal sequencing of the polypeptide gave a contiguous sequence of 20 amino acids showing no hom ologies to PS II polypeptides as yet sequenced. After chromatography o f the L-AM E on an anion exchange column at pH 9.5 (last purification step) a completely inactive enzyme was obtained. Maximal reactivation was achieved by dialyzing the protein against H epes-N aO H buffer in the pH range of 6.5 to 7.5 containing 100 m M chloride or sulfate (being the most effective anions). The L-AM E activity was totally dependent on manganese added to the reaction mixture. Moreover, there were indications of a second cation binding site being more sequestered and requiring bound Ca2+ or Mn2+ for activity (Sr2+ was less effective and Mg2+ was ineffective). There are indications that the protein contains a redox active group -possibly an amino-acid-derived quinonoid (based on a redox cycling assay with glycine and nitroblue tetrazo-lium). The capability of this PS II associated protein to bind the cofactors of water oxidation and having a redox active group (preliminary results) suggests that this protein might be functional in photosynthetic water oxidation. This is further supported by the fact that the isolated L-AM E has a low catalase activity. 
  Reference    Z. Naturforsch. 50c, 638—651 (1995); received May 22/July 10 1995 
  Published    1995 
  Keywords    L-Arginine Metabolizing Enzyme, Water Oxidizing Enzyme, Photosystem II, Quinoproteins 
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 TEI-XML for    default:Reihe_C/50/ZNC-1995-50c-0638.pdf 
 Identifier    ZNC-1995-50c-0638 
 Volume    50 
32Author    L. Kovács3, U. Hegdeb, S. Padhyeb, G. Bernät3, S. Demeter3Requires cookie*
 Title    Effects of Potassium-(picrate)-(18-crown-6) on the Photosynthetic Electron Transport  
 Abstract    The effects of potassium-(picrate)-(18-crown-6) on the electron transport of photosystem II was investigated in isolated pea thylakoids. Low concentrations of the compound inhibited the fast decay of fluorescence yield associated with electron transfer between the primary (Q a) and secondary (Q b) quinone electron acceptor and increased the intermediary level of fluorescence to the Fmax level. The decay half-time of fluorescence yield measured in the presence of D C M U (S2Q A' charge recombination) decreased from about 1.8 s to about 0.3 s in thylakoids treated with potassium-(picrate)-(18-crown-6). W hile the inhibition of electron transport by D C M U gave rise to the appearance of a thermoluminescence band at about + 10°C (S2Q A~charge recombination) addition of potassium-(picrate)-(18-crown-6) resulted in a thermoluminescence band at about -10°C. Increasing concentrations of potassium-(picrate)-(18-crown-6) diminished the fluorescence yield and the -10°C TL band and abolished the Signal II S and Signal I I f E P R signals of the tyrosine-D and tyrosine-Z electron donors, respec­ tively. The phenolic-type inhibitor, potassium picrate had the same effect on thermolumines­ cence and on the tyrosine E P R signals. It is concluded that potassium-(picrate)-(18-crown-6) is a phenolic type inhibitor owing to its picrate constituent. A t low concentrations picrate and potassium-(picrate)-18-crown) not only block the electron transport between Q A and O b but they probably decrease the midpoint redox potential of Q A, as well. A t high concen­ trations they also inhibit the light-induced oxidation of the tyrosine-D and tyrosine-Z donors. 
  Reference    Z. Naturforsch. 51c, 539—547 (1996); received December 22 1995/ 
  Published    1996 
  Keywords    Phenolic Inhibitors, Photosynthesis, Photosystem II, Thermoluminescence, Electron Paramagnetic Resonance 
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 TEI-XML for    default:Reihe_C/51/ZNC-1996-51c-0539.pdf 
 Identifier    ZNC-1996-51c-0539 
 Volume    51 
33Author    G. H. Schmida, A. R. Adunz3, K.P B Ader3, B. Myśliwa-Kurdzielb, K. Strzał, J. KrukbRequires cookie*
 Title    Action of an Antiserum to a-Tocoquinone on Photosystem II-Particle Preparations of N icotiana tabacum  
 Abstract    An antiserum to a-tocoquinone was prepared by immunization of rabbits. Immunization was obtained by injection of a conjugate consisting of the hapten a-tocoquinone attached to methylated ovalbumin into the rabbit. The antiserum recognizes the 3,4-dimethyl-p-benzo-quinone group of the m olecule as well as part of the immediate vicinity to the side chain. This is concluded from the fact that the antibody has som e affinity also to plastoquinone. No reaction of the antibody is observed with a-tocopherol hydroquinone or a-tocopherol. Reac­ tion of the antiserum to a-tocoquinone with photosystem Il-particle preparations from to­ bacco affects the functionality of the preparation. Chlorophylla-fluorescence emission is quenched without an alteration of the em ission spectrum. Concomitant with this fluorescence quenching, the lifetime of two fluorescence com ponents namely that of a fast and a slower component are shortened. By analogy with the literature the fast component is associated with chlorophylla of the reaction center core and that of the slow com ponent with the antenna system in which the lifetime parameter is shortened by the antibody from 3.42 ns to 1.795 ns. The action on the fast component is less and leads to a shortening of the lifetime parame­ ter from 0.373 ns to only 0.249 ns. The effect is interpreted in terms of an enhancement of linear photosynthetic electron transport possibly due to an inhibition of the cyclic electron transport around PS II, discovered by Gruszecki et al. 
  Reference    Z. Naturforsch. 51c, 691—6 (1996); received May 14/July 17 1996 
  Published    1996 
  Keywords    Antiserum, a-Tocoquinone, Photosystem II, Fluorescence Lifetime, Nicotiana tabacum 
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 TEI-XML for    default:Reihe_C/51/ZNC-1996-51c-0691.pdf 
 Identifier    ZNC-1996-51c-0691 
 Volume    51 
34Author    E.K N Én, N. Én, É. Th, M. F. RagataRequires cookie*
 Title    Effect of MgCl2 and Phosphatidylglycerol on CaCl2-Mediated Recovery of Oxygen Evolution in a Photosystem II Complex Depleted of the 17 and 24 kDa Extrinsic Proteins  
 Abstract    Phosphatidylglycerol (PG) is an anionic lipid of the thylakoid m em brane of higher plant chloroplasts. PG was shown previously to stimulate the evolution of oxygen in intact pho­ tosystem II (PSII) membranes [Fragata, M., Strzalka, K. and Nenonene, E. K. (1991) J. Pho-tochem. Photobiol. B: Biol 11, 329-342], In this work, a study was undertaken of the effect of MgCl2 and PG on the CaCl2-mediated recovery of oxygen evolution in a PSII complex depleted of the extrinsic proteins (EP) of molecular masses 17 kDa (EP17) and 24 kDa (EP24), hereunder designated d 1724PSII. This molecular system is structurally close to the PSII core complex of cyanobacteria and is therefore useful in the comparative analysis of PSII-PG relationships in cyanobacteria and the higher plants. This work reveals a new aspect of the thylakoid lipids role in the PSII function, namely the PG effect on intact PSII is observed as well in d 1724PSII. The results show that phosphatidylglycerol has the ability to compensate for the loss of EP17 and EP24 in the PSII complex. That is, PG restores the oxygen evolution in d 1724PSII incubated in the presence of MgCl2 and/or CaCl2 to the levels observed in native PSII. M oreover, the site of H 20 degradation in d 17 24PSII, including most probably the pool of calcium and chloride ions, would seem to be protected by phosphatidyl­ glycerol. This suggests that one of the docking sites of PG in the PSII complex is near EP24, inasmuch as this extrinsic protein participates in the regulation of the affinity of the calcium and chloride ions to the water oxidation site. Furtherm ore, taking into account that in d j7 24PSII the PSII core complex is directly exposed to PG, then the phospholipid effect reported here indicates that phosphatidylglycerol might be a functional effector and mem­ brane anchor of the D1 protein in the PSII core complex as was shown recently in the cyanobacterium Oscillatoria chalybea [Kruse, O. and Schmid, G. H. (1995) Z. Naturforsch. 50c, 380-390], 
  Reference    Z. Naturforsch. 53c, 39—4 (1998); received September 1/October 24 1997 
  Published    1998 
  Keywords    Extrinsic Proteins, Oxygen Evolution Recovery, Phosphatidylglycerol, Photosystem II, Salt-Mediated Effects 
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 TEI-XML for    default:Reihe_C/53/ZNC-1998-53c-0039.pdf 
 Identifier    ZNC-1998-53c-0039 
 Volume    53 
35Author    Jaber Rahoutei3, MatildeB. Arón3, IsabelG. Arcía-Luqueb, Magdolna Droppac, András Neményic, G. Ábor, H. OrváthcRequires cookie*
 Title    Effect of Tobamovirus Infection on Thermoluminescence Characteristics of Chloroplasts from Infected Plants  
 Abstract    Changes of thermoluminescence characteristics as well as the 0 2-evolving capacity was analysed in chloroplasts isolated from Nicotiana benthamiana infected with pepper and pa­ prika mild mottle viruses and their chimeric hybrids. The electron transport activity in thyla­ koids of virus-infected plants was inhibited and could be restored by adding DPC or Ca2+ which indicated that the virus infection altered the oxygen-evolving complex. In thermolumi­ nescence characteristics of plants infected with either viruses, the first well defined response was a shift in the peak position of the B band from 20 °C to 35 °C corresponding to S3(S2)Q b-and S2Q b~ charge recombinations, respectively, which showed an inhibition in the formation of higher S states in the water splitting system. Simultaneously, a new band ap­ peared around 70 °C due to chemiluminescence of lipid peroxidation. Further progress of the viral infection dramatically decreased the intensity of bands originated from charge re­ combinations with a concomitant increase of the band at 70 °C indicating the general oxida­ tive breakdown of injured thylakoids. 
  Reference    Z. Naturforsch. 54c, 634 (1999); received November 15 1998/January 15 1999 
  Published    1999 
  Keywords    Biotic Stress, Photosynthetic Electron Transport, Photosystem II, Thermoluminescence, Virus Infection 
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 TEI-XML for    default:Reihe_C/54/ZNC-1999-54c-0634.pdf 
 Identifier    ZNC-1999-54c-0634 
 Volume    54 
36Author    Sándor Dulai3, István Molnár3, Evelin Pélia, Endre LehoczkiabRequires cookie*
 Title    Short-Term Responses of Photosystem II to Heat Stress in Cold-Acclimated Atrazine-Resistant and Susceptible Biotypes of Erigeron canadensis (L.)  
 Abstract    When leaves of atrazine-resistant (A R) and atrazine-sensitive (S) Erigeron canadensis (L.) plants grown at 5 °C were exposed to an elevated temperature (35 °C) for 30 min, the critical (T c) and peak temperatures (Tp) of the F0 vs. T curves were considerably higher for the leaves of the S biotype, but not for those of the A R biotype. The temperature dependences of F J F m and AFIFm' were not greatly different for the heat-treated cold-acclimated A R biotype, in contrast with the situation for the S plants. This short-term heat treatment resulted in a more significant shift in the optimal thermal interval of C 0 2 fixation for the S than for the A R biotypes. 
  Reference    Z. Naturforsch. 54c, 665 (1999); received November 2 1998/February 19 1999 
  Published    1999 
  Keywords    Erigeron canadensis, Heat Stress, Chlorophyll Fluorescence, Photosystem II, Photosynthesis 
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 TEI-XML for    default:Reihe_C/54/ZNC-1999-54c-0665.pdf 
 Identifier    ZNC-1999-54c-0665 
 Volume    54 
37Author    Merope Tsimilli-Michaelab, Martin Pêcheux3, RetoJ. Strasser3Requires cookie*
 Title    Light and Heat Stress Adaptation of the Symbionts of Temperate and Coral Reef Foraminifers Probed in Hospite by the Chlorophyll a Fluorescence Kinetics  
 Abstract    Since the early 80's massive bleaching affects the reef ecosystem. It involves, besides corals, several other species among which large foraminifers, and it corresponds to the loss of their photosynthetic symbionts or the symbionts' pigments. The cause is unclear, though temper­ ature elevation and strong irradiation have been considered to be primary factors. In this work we investigated in two genera of coral reef foraminifers (Amphistegina lobifera and Amphisorus heimprichii) and in the temperate foraminifer Sorites variabilis the response of photosystem II (P SII) of their symbionts in hospite upon light stress (white light of 550 |aE n r 2 s_1 and red light of 3200 |iE m~2 s" 1) and heat stress (up to 32 °C), by means of the Chla fluorescence transients O -J-I-P they exhibit upon illumination. The transients were analysed according to the JIP-test which leads to the calculation of several structural and functional parameters providing a quantification of PSII behaviour. We observed that the various parameters undergo modifications that differ concerning both their extent and their degree of elasticity, thus indicating that different adaptive strategies are employed in response to stress. The most pronounced of these regulatory changes is a wide decrease of the quantum yield of electron transport. However, the extent of the changes, different for the three studied species, was in general smaller when the cultures were kept under low light (70 ^iE m -2 s-1) than in darkness. By the applied stressors, PSII was not damaged and, except for some cells in which an expulsion of symbionts was initiated, no bleaching was observed. This can be well correlated with the observed adaptability of PSII. As a working hypothesis, it is proposed that the decrease of the capacity for electron transport activity might be among the factors trigger­ ing bleaching in the field. 
  Reference    Z. Naturforsch. 54c, 671 (1999); received November 10 1998 
  Published    1999 
  Keywords    Coral-Reef Bleaching, Electron Transport Activity, JIP-test, Photosystem II, Thermoprotection 
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 Identifier    ZNC-1999-54c-0671 
 Volume    54 
38Author    Salil Bose, R. M. Annar, M. Annan, C. J. ArntzenRequires cookie*
 Title    Increased Synthesis of Photosystem II in Triticum vulgare when Grown in the Presence of BAS 13-338  
 Abstract    Addition o f BAS 13-338 (4-chloro-5-dim ethylam ino-2-phenyl-3(2H)-pyridazinone) to a sus­ pension o f chloroplast thylakoids caused an increase in the / level o f chlorophyll fluorescence induction without affecting the F0 level and with a slight decrease in the Fmax level in a manner similar to the addition o f D C M U to a thylakoid suspension. A ddition o f BAS 13-338 also inhibited the rate o f Hill reaction H20 -» dichlorophenol indophenol with 50% inhibition occurring at about 10 hm BAS 13-338. The inhibition was not reversed by diphenyl carbazide used as an artificial electron donor to photosystem II. These results suggest that the site o f in h ib i­ tion by BAS 13-338 is between Q (next to the primary electron acceptor) and plastoquinone. When the plants were grown in the presence o f sublethal dose o f BAS 13-338, the follow ing changes were noted in the thylakoids o f the treated plants as com pared to the thylakoids isolated from the control plants: The F0 and the norm alized variable fluorescence (4F/F0) levels increased, chlorophyll a/b ratio decreased, chlorophyll/P 700 ratio increased. Furthermore, the rate o f photosystem II electron transport both under saturated intensity and the lim iting intensity of illumination increased, and the ratio o f plastoquinone to Q decreased. These observations have been interpreted as due to an increase in the ratio o f photosystem II to photosystem I in plants grown in the presence o f BAS 13-338. 
  Reference    Z. Naturforsch. 39c, 510 (1984); received D ecem ber 1 1983 
  Published    1984 
  Keywords    Photosynthesis, Electron Transport, Chlorophyll Fluorescence, Photosystem II, BAS 13-338 
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 Identifier    ZNC-1984-39c-0510 
 Volume    39 
39Author    Jean-M Arc, D. Ucruet, Rene ScallaRequires cookie*
 Title    Action of Methylthiopyrimidine Experimental Herbicides as Diuron-Like Inhibitors of Photosynthesis  
 Abstract    Derivatives of 6-chloro-5-methylthiopyrimidines provide potent inhibitors of the photosynthe­ tic electron flow, which act like Diuron on fluorescence induction kinetics and competitively displace it from its binding site. Structure-activity relationships show that, unlike triazines, ac­ tivities of 2-or 4-alkylamino derivatives are restricted by steric hindrances. Decreases in inhibit­ ory activities of these compounds observed in triazine-resistant chloroplasts are lower than de­ creases reported for triazines themselves. 
  Reference    Z. Naturforsch. 40c, 388 (1985); received October 31 1984/February 1 1985 
  Published    1985 
  Keywords    Methylthiopyrimidines, Diuron-Like Inhibitors, Photosynthesis, Structure-Activity Correlations, Photosystem II 
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 Identifier    ZNC-1985-40c-0388 
 Volume    40 
40Author    Hiroyuki Koike, Yasuhiro Kashino, Kazuhiko SatohRequires cookie*
 Title    Interactions of Halogenated Benzoquinones with the Non-Heme Iron (Q40o) in Photosystem II  
 Abstract    Interactions o f halogenated benzoquinones with the acceptor side o f Photosystem (PS) II were studied by measuring fluorescence induction curves and flash-induced absorbance changes in PS II particles isolated from Synechococcus vulcanus. Following results were ob­ tained: 1) Addition o f some halogenated benzoquinones prior to 3-(3,4-dichlorophenyl)-l,l-dimethylurea (D C M U) in the dark increased the area above the fluorescence induction curve (work integral) by a factor o f two. 2) Based on the ability to increase the fluorescence work integral, halogenated benzoquinones could be divided into two groups. 3) 2,6-D ichlorobenzo-quinone (2,6-D C BQ), trichlorobenzoquinone (TCBQ) and tetrahalogenated benzoquinones except tetrafluorobenzoquinone (fluoranil) (group A) increased the work integral, but 2,5-D CBQ and fluoranil (group B) did not. 4) Rapid reoxidation o f QA was observed in the presence o f quinones which belong to group A. These results were interpreted in terms o f dark oxidation o f by quinones belonging to group A. Possible mechanisms o f oxidation o f Q400 by these quinones in the dark are discussed. 
  Reference    Z. Naturforsch. 48c, 168 (1993); received Novem ber 9 1992 
  Published    1993 
  Keywords    Photosystem II, Q400, Halogenated Benzoquinone, Q B-Site, Fluorescence Induction 
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 TEI-XML for    default:Reihe_C/48/ZNC-1993-48c-0168.pdf 
 Identifier    ZNC-1993-48c-0168 
 Volume    48 
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