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1Author    Magdolna Droppa, Sándor Demeter, Zsuzsa Rózsa, G. Ábor HorváthRequires cookie*
 Title    Reinvestigation of the Effects of Disalicylidenepropanediamine (DSPD) and 2-HeptyM-hydroxyquinoline-N-oxide (HQNO) on Photosynthetic Electron Transport  
 Abstract    The effects of disalicylidenepropanediamine (DSPD) and 2-heptyl-4-hydroxyquinoline-N-oxide (HQNO) on photosynthetic electron transport have been reexamined. The results confirm earlier observations that lower concentrations of DSPD (< 100 hm) block electron transport at the levels of ferredoxin and plastocyanin. High concentrations o f DSPD even inhibit electron transport from HaO -> pBQ, suggesting that DSPD has an inhibitory site in PS II as well. Thermoluminescence curves o f DSPD and DCMU treated chloroplasts were very similar, showing that the third inhibitory site o f DSPD is similar to that o f DCMU. Both oxidized and reduced HQNO, (0 .6 -6 hm) blocked electron transport from H20 -* pBQ, H20 -*■ MV/FeCy to a similar extent. The effect of HQNO on thermoluminescence showed that its inhibitory site is probably located before that o f DCMU. At higher concentration (> 6 h m) , the H20 -*■ MV/FeCy reactions were more strongly inhibited by oxidized HQNO than those occuring from H20 -> pBQ, suggesting that a new site o f inhibition must also be considered. The dark decay of the P 700 signal was not influenced by the addition o f oxidized HQNO which shows that the new inhibitory site of HQNO is located between plastoquinone and P 700. The reduced form of HQNO did not inhibit non-cyclic electron transport around PS I. Indeed, at higher concentrations, reduced HQNO even accelerates electron flow from DCIP -» MV and the dark reduction of P 700, thus suggesting that this compound has a "donor-mediator" function in PS I. 
  Reference    Z. Naturforsch. 36c, 109 (1981); received September 8/October 28 1980 
  Published    1981 
  Keywords    Inhibitors, Electron Transport, Chloroplasts, Thermoluminescence 
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 TEI-XML for    default:Reihe_C/36/ZNC-1981-36c-0109.pdf 
 Identifier    ZNC-1981-36c-0109 
 Volume    36 
2Author    Magdolna Droppa, Sándor Dem, G. Ábor, H. OrváthRequires cookie*
 Title    Two Sites of Inhibition of the Photosynthetic Electron Transport Chain by the Herbicide Trifluralin  
 Abstract    The effect o f trifluralin on the photosynthetic electron transport has been investigated by oxygen evolution and thermoluminescence m easurem ents. The results confirm the earlier observations that trifluralin at low concentrations blocks electron transport between the two photosystems probably at the same site as DBMIB does. A t higher concentrations however, trifluralin inhibits the reaction from H aO -*■ /?BQ also and affects the thermoluminescence of chloroplasts in a manner sim ilar to DCM U. These results suggest that trifluralin has a second inhibitory site therefore the use o f trifluralin as a specific inhibitor o f electron transport has to be questioned. 
  Reference    Z. Naturforsch. 36c, 853—855 (1981); received June 25 1981 
  Published    1981 
  Keywords    Herbicide, Inhibition, Photosynthetic Electron Transport, Trifluralin, Thermoluminescence 
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 TEI-XML for    default:Reihe_C/36/ZNC-1981-36c-0853.pdf 
 Identifier    ZNC-1981-36c-0853 
 Volume    36 
3Author    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 
4Author    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 
5Author    Nir Ohad3, Dekel Amir-Shapirab, Hiroyuki Koikec, Yorinao Inouec, Itzhak Ohadb, Joseph Hirschberg3Requires cookie*
 Title    Amino Acid Substitutions in the D 1 Protein of Photosystem II Affect Q b-Stabilization and Accelerate Turnover of D  
 Abstract    Isogenic strains of Synechococcus PCC 7942 were genetically engineered so that copy I of the gene psbA was mutated at specific sites. These mutations resulted in replacements of Ser 264 by Gly or Ala and of Phe 255 by Tyr or Leu in the D 1 protein. The mutants were resistant to herbicides inhibiting electron transfer in photosystem II. All mutants exhibited alterations in the stability of Q B' as demonstrated by a temperature downshift, to various extents, of the in vivo thermoluminescence emission. Measurements of the light-dependent turnover of D 1 showed a marked decrease in the 11 / 2 of this protein in the mutants as compared to wild-type, under low to medium light intensities. A correlation was found between the degree of pertur­ bation in the Q B" stability and the rate of acceleration in the turnover of D 1. These data pro­ vide a direct evidence for the overlapping binding sites for the plastoquinone B and herbicides in the D 1 protein. In addition these data indicate a close link between Q B" destabilization in reaction center II and the mechanism controlling the light-dependent turnover of D 1. Based on these results and previous work we suggest that destabilization of the semireduced quinone, facilitates a light-induced damage in D 1 which triggers its degradation. 
  Reference    Z. Naturforsch. 45c, 402—408 (1990); received November 21 1989 
  Published    1990 
  Keywords    Herbicide Resistance, Thermoluminescence, D 1 Turnover, Synechococcus PCC 7942 
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 TEI-XML for    default:Reihe_C/45/ZNC-1990-45c-0402.pdf 
 Identifier    ZNC-1990-45c-0402 
 Volume    45 
6Author    Jack FarineauRequires cookie*
 Title    In Pea Thylakoids, a Special Thermoluminescence Band Was Observed at Low Temperature after Photoinhibitory Treatments Performed under Aerobic Conditions, either in vivo (in Leaf) or in vitro  
 Abstract    Characteristics o f thermoluminescence (TL) glow curves were studied in thylakoids isolated from pea leaves after an exposure to very high light in the TL device. The inhibition o f p h oto­ synthesis was detected both as decreases o f oxygen evolution rates and o f variable fluores­ cence. In another more classical experiment, leaves were exposed to high light at low tempera­ ture (5 °C) for 4 h and recovery o f normal PS II characteristics were followed during a 20 h time period under low light at 20 °C. TL study was performed on thylakoids isolated from these leaves. Charging o f bands was performed by an illumination at low temperature (-8 0 °C). Illumination at low temperature (-8 0 °C) induces 2 types o f TL bands called Z variable (Zv) band peaking at about —70 °C and a classical B band peaking at 35 °C. B band is ascribed to recombination in pairs S2/3QB", whereas the origin o f Zv bands remains unclear. M odified Zv bands, with flat shape and presenting a large part resistant to ethanol, were evidenced after som e minutes o f dark adaptation, both in light-exposed thylakoids and in thylakoids isolated from photoinhibited leaves. This ethanol resistant part in Zv band was only induced by p h oto­ inhibitory treatment performed under aerobic conditions (2 1 % 0 2 in media), both in vitro and in vivo; thus, the appearance o f the special Zv band would be related to an oxidative process accompanying photoinhibition. B bands presented reduced sizes and a shift o f peak maximum o f about 5 °C after some minutes o f dark adaptation. In vivo, the recovery o f a high PS II activ­ ity and o f B bands displaying normal characteristics occurs parallely to reappearance o f Zv bands with normal shape and with a vestigial ethanol resistant band. 
  Reference    Z. Naturforsch. 47c, 875—8 (1992); received July 27/A ugust 27 1992 
  Published    1992 
  Keywords    Pea, Photoinhibition, Photosystem II, Thermoluminescence, Thylakoid, Zv Band 
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 TEI-XML for    default:Reihe_C/47/ZNC-1992-47c-0875.pdf 
 Identifier    ZNC-1992-47c-0875 
 Volume    47 
7Author    H. Adar Kless3, Michal Oren-Shamirb, ItzhakO. Hadc, M. Arvin Edelm, Wim VermaasaRequires cookie*
 Title    Protein Modifications in the D 2 Protein of Photosystem II Affect Properties of the Q B/Herbicide-Binding Environment  
 Abstract    The D 2 protein contains an extended loop (the D-de loop) between helices D and de at the reducing side o f photosystem II (PS II). Characterization o f D 2 mutants o f the cyanobacte­ rium Synechocystis sp. PCC 6803 has indicated that the length and amino acid com position o f the D-de loop are not critical for basic PS II functions, although most o f the residues in that region are conserved phylogenetically. Here we show using herbicide binding and electron-flow inhibition measurements that drastic modifications in the D-de loop o f the D 2 protein modify the interaction o f some PS II-directed herbicides with their binding niche. The stability o f (semi-)reduced Q B in its binding pocket is altered in at least two o f the mutants, as indicated by a shifted peak temperature o f the thermoluminescence signal originating from charge recombi­ nation involving QB. These results suggest a close functional association between the D-de loop o f the D 2 protein and the Q B/herbicide-binding environment, which is viewed as being coordinated mostly by re­ sidues o f the D 1 protein. This represents one o f the first examples o f m odification o f the Q B/ herbicide-binding domain by mutations in the D 2 protein. 
  Reference    Z. Naturforsch. 48c, 185—190 (1993); received November 23 1992 
  Published    1993 
  Keywords    Herbicides, Plastoquinone, Photosystem II, Thermoluminescence, Cyanobacteria 
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 TEI-XML for    default:Reihe_C/48/ZNC-1993-48c-0185.pdf 
 Identifier    ZNC-1993-48c-0185 
 Volume    48 
8Author    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 
9Author    Jack Farineaua, DanielleM. Laval-, ArtinbRequires cookie*
 Title    Characteristics of Thermoluminescence Bands of Euglena Cells Belonging to 2 Lines Presenting Different Degrees of Diuron-Resistance  
 Abstract    We have analysed the thermoluminescence (TL) properties of two lines o f Euglena exhibit­ ing two degrees of resistance to diuron, by a factor of 100 (Z R 25) and 1000 (Z R 250) respectively, as compared to wild type line (Z). In addition, the two ZR lines developped an identical resistance to atrazine since the I50 for this herbicide in each line was 75 times larger than in wild type. Special TL characteristics were evidenced in the two lines. Bands after 2 flashes (or more) showed a shift o f the peak maximum towards low temperature, the shift being the largest in the most DCM U-resistant cells. Similar results were obtained with isolated thylakoids, except that the TL bands appeared at a temperature higher than in corresponding cells. Oscillations in the amplitude of the bands in a flash sequence were largely damped in cells (and thylakoids), particularly in the most DCM U-resistant lines. The results are interpreted as indicating accumulation of Q a "Qb after flashes due to a decrease of the equilibrium constant for the reaction Q a ~Qb ^ QaQb~ accompanying the D CM U resistance. 
  Reference    Z. Naturforsch. 50c, 86—9 (1995); received October 12/November 21 1994 
  Published    1995 
  Keywords    Diuron, Euglena, Herbicide-Resistance, Photosystem II, Thermoluminescence 
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 TEI-XML for    default:Reihe_C/50/ZNC-1995-50c-0086.pdf 
 Identifier    ZNC-1995-50c-0086 
 Volume    50 
10Author    Tibor Janda3, Gabriella Szalai3, Catherine Giauffretb, Emil Páldi3, Jean-M Arc DucruetcRequires cookie*
 Title    The Thermoluminescence 'Afterglow' Band as a Sensitive Indicator of Abiotic Stresses in Plants  
 Abstract    Single turn-over xenon flashes induce a thermoluminescence (TL) B-band centred near 35 °C. The far-red illumination of leaves at non-freezing temperatures induces a band peaking at around 45 °C (afterglow or AG-band), together with a downshifted B-band peaking be­ tween 15 °C and 28 °C. In control, unfrozen wheat plants, the Tmax of the B-band induced after 30 s far-red light at 0 °C was approx. 1 5 -1 8 °C. In maize plants grown under the same conditions, this far-red-induced downshift was not so strong, since the B-band peaked at 2 8 -30 °C. Both a decline in the AG-band and a reversal of the downshift of the B-band were observed after short-term freezing in several plant species. There was usually a sudden drop in the AG-band below a critical freezing temperature. However, while in wheat plants a weak TL emission could be seen between 4 0 -5 0 °C in frozen samples, in cold-sensitive maize plants this was completely suppressed and only the B-band could be detected. In cold-har­ dened wheat plants the temperature at which the AG-band was suppressed was lower than in non-hardened plants. Drought and short-term heat stress also affect the AG-band. As the AG-band was found to be more sensitive to several types of stresses than the B-band, it can be used as a sensitive stress indicator. However, the behaviour of the AG-band depends on several factors (for example the age of the leaf, etc.), which must be controlled if different species or varieties are to be compared. 
  Reference    Z. Naturforsch. 54c, 629 (1999); received O ctober 31 1998/January 25 1999 
  Published    1999 
  Keywords    Afterglow, Drought, Freezing, Heat Stress, Thermoluminescence 
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 TEI-XML for    default:Reihe_C/54/ZNC-1999-54c-0629.pdf 
 Identifier    ZNC-1999-54c-0629 
 Volume    54 
11Author    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 
12Author    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 
13Author    Susana Shochata, Noam Adira, Alma Gala, Yorinao Inoueb, Laurence Metsc, Itzhak OhadaRequires cookie*
 Title    Photoinactivation of Photosystem II and Degradation of the D 1 Protein are Reduced in a Cytochrome b j f -Less Mutant of Chlamydomonas reinhardtii  
 Abstract    The effect of unoccupancy of the Q B site by plastoquinone on the photoinactivation of reac­ tion center II in a Cyt b jf-less mutant of Chlamydomonas reinhardtii, Bb, was investigated. In these cells the oxidation of plastoquinol generated by electron flow via RC II to plastoquinone and thus the turnover of PQH2/PQ via the Q B site are drastically reduced. Reaction center II of the mutant cells was resistant to photoinactivation relative to the control cells as demonstrated by measurements of light-induced destabilization of S2-QB charge recombination, rise in in­ trinsic fluorescence and loss of variable fluorescence. These parameters relate to functions in­ volving the reaction center II D 1 protein. The light-induced degradation of D 1 in the mutant cells was also considerably reduced, with a ;l/ 2 value of 7 h as compared, under similar condi­ tions, to about 1.5 h for the control cells. These results indicate that the photoinactivation of RC II and turnover of the D 1 protein are related and require occupancy of the Q B site by PQ and its light-driven reduction. 
  Reference    Z. Naturforsch. 45c, 395—401 (1990); received November 24 1989 
  Published    1990 
  Keywords    Cytochrome b j f, Chlamydomonas, D 1 Turnover, Q B, Thermoluminescence, Photoinhibition 
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 TEI-XML for    default:Reihe_C/45/ZNC-1990-45c-0395.pdf 
 Identifier    ZNC-1990-45c-0395 
 Volume    45