Thermoluminescence characteristics of granal and agranal chloroplasts of maize

Demeter, S.; Herczeg, T.; Droppa, Magdolna; Horváth, Gábor

doi:10.1016/0014-5793(79)80361-0

Cited by 37 publications

(13 citation statements)

References 12 publications

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“…6, relatively low concentrations of acridone abolished both the B and Q bands of the glow curves, which correspond to S2S3QB and S2(S3)QA recombination, respectively (20). This is in agreement with the earlier observation that the powerful ADRY reagents ANT-2p or CCCP abolished both the B and Q bands by accelerating the reduction of oxidizing redox equivalents stored in S2 and S3 states within the water-splitting enzyme (21)(22)(23). In the concentration range affecting the Q and B bands, acridone even enhanced the intensity of the bands at -20°C and +50°C (Fig.…”

Section: Resultssupporting

confidence: 80%

Acridones: a chemically new group of protonophores.

Horváth¹,

Droppa²,

Fodorpataki³

et al. 1996

Proc. Natl. Acad. Sci. U.S.A.

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Although the interaction of proton-conducting ionophores (protonophores) with photosynthetic electron transport has been extensively studied during the past decade, the mode of action of protonophores remained uncertain. For a better understanding of the molecular mechanism of the action of protonophores, the introduction of chemically new types of molecules will be required. In this work, we demonstrate that acridones (9-azaanthracene-10-ones) completely fulfill this requirement. At low concentrations of acridones, the thermoluminescence bands at +20°C and +10°C were strongly inhibited, while normal electron transport activity was retained. The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact.In this study we present evidence that acridones (9-azaanthracene-10-ones) (6) operate as typical protonophores, accelerating the decay of the electrochromic absorbance transient and inhibiting the buildup of the transmembrane ApH. It is also shown that these agents uncouple photophosphorylation and act as an ADRY reagent (accelerators of deactivation reactions of the water-splitting enzyme, Y). Acridones also facilitate the oxidation of the high potential form of cytochrome b559 and its conversion into intermediary-or lowpotential forms. MATERIALS AND METHODSPeas (Pisum sativum cv. Rajnai torpe) were grown under standard greenhouse conditions, and leaves were freshly harvested before each experiment. Intact chloroplasts were isolated essentially as described by Thorne et al. (7), and the chlorophyll content of the samples was estimated as described by Arnon (8).The rate of photosynthetic oxygen evolution and uptake was measured as described by Droppa et al. (9) by using a Clarktype 02 electrode (Rank Brothers, Cambridge, U.K.). Different parts of the electron transport chain were studied by the addition of various electron donors and acceptors: 2 mM NaN3 and either 2 mM K3[Fe(CN)6] or 0.1 mM methyl viologen were used to assay the whole electron-transport chain. Photosystem I (PSI) or PSII electron transport was measured by using 0.25 mM p-benzoquinone or 2,5-dichloro-p-benzoquinone, 40 tLM dichlorophenolindophenol, and 2 mM ascorbate, depending on which system was being studied. In specific instances, PSII activity was also measured spectrophotometrically following the photoreduction of dichlorophenolindophenol at 590 nm in the presence and absence of 0.5 mM sym-diphenylcarbazide.Thermoluminescence was measured in the temperature interval from -80 to +80°C with an apparatus similar to that described by Vass et al. (10). Samples were illuminated with white light of 10 W.m-2 for 2 min during continuous cooling from +20 to -80°C and then heated at a constant rate of 20°C/min to measure glow curves. Chemicals were added before the illumination started (11).Fluorescence induction was measured by using a chlorophyll fluorimeter (Biotechnika RT, Szeged, Hungary). Sa...

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Section: Resultssupporting

confidence: 80%

Acridones: a chemically new group of protonophores.

Horváth¹,

Droppa²,

Fodorpataki³

et al. 1996

Proc. Natl. Acad. Sci. U.S.A.

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“…As has been shown previously, the A and B bands corresponded to S3QA− and S2S3QB− charge recombinations, respectively, and were strongly influenced by inhibitors interrupting electron transport between QA and QB (for review see Horváth 1986;Demeter and Govindjee 1989;Vass and Govindjee 1996). The elimination of both bands with PS II herbicides can be explained by the fact that neither S3 state is formed (due to one turnover) nor QB reduction can occur (Demeter et al 1979;Droppa et al 1981). Treatment of thylakoids with increasing concentrations of Cu(II) showed a drastic decrease in the intensity of the B band, while that of the A band was not significantly decreased ( Figures 1B, C and 2).…”

Section: Resultsmentioning

confidence: 96%

“…TL of 0.5 ml suspension containing 125 μg chlwas measured using an apparatus similar to that described earlier (Demeter et al 1979). The light source was a 650 W tungsten lamp provided 10 W/m2 intensity at the surface of the sample.…”

Section: Methodsmentioning

confidence: 99%

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Horváth¹,

Arellano

Droppa³

et al. 1998

Photosynthesis Research

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The thermoluminescence characteristics of functionally intact thylakoids and TRIS-washed BBY particles werestudied under Cu(II) poisoned conditions. In thylakoids, both the A and B thermoluminescence bands correspondingto S3QA− and S2S3QB− charge recombinations, respectively showed specific responses to Cu(II) treatment. The amplitude of the B band was gradually decreased, which corresponds to the Cu(II) induced inactivation ofTyrZ. The simultaneous stepwise shift in the peak position of the B band indicated, however, that S3QB− chargere combination is more resistant to Cu(II) poisoned conditions. The shifted peak position of the A band toward thehigher temperature in Cu(II) treated thylakoids also showed a change in the redox span between the recombination partners generating the A band of the glow curve. The AT band due to the HisCQA− recombination in TRISwashedBBY particles was insensitive to Cu(II) addition indicating that Cu(II) did not affect either HisC or QA−. The unaffected intensity of the A and AT bands when Cu(II) inhibits TyrZ function favours the assumption of an alternative pathway in which functional TyrZ is not required. In addition, Cu-induced changes of the TL bands were compared to those produced by the Tyr and His modifiers NBD and DEPC, respectively.We obtained very similar results regarding TL bands by either adding NBD or Cu-poisoning in functional thylakoids. Regarding DEPC, the A and AT bands were abolished by increasing concentrations of the His modifier. This effect was associated with the decrease of the B band and its replacement by the Q band at around 0 ºC. Comparing our data obtained by Cu, NBD and DEPC treatments, we have found a strong interrelation between HisC and S3 state. We assume that in some inhibitory conditions in the S3 state His is oxidized in place of Mn and this alternative pathway does not require functional TyrZ.Abbreviations: DCMU-3-(3,4-dichlorophenyl)-1,1-dimethylurea; DEPC-diethyl pirocarbonate; NBD-7-chloro-4-nitrobenz-2-oxa-1,3-diazole; PS II -Photosytem II; QA and QB -the primary and secondary quinine acceptors of PS II; TL -thermoluminescence; TyrZ -tyrosine species acting as a donor to P680.

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“…The T L of leaf discs with a 10 mm diameter or 0.5 ml chloroplast suspension containing 125 |.ig chi were measured using an apparatus similar to that described earlier (Demeter et al, 1979). The light source was a 650 W tungsten lamp provided 10 W m -2 irradiance on the surface of the sample.…”

Section: Measurement O F Thermoluminescencementioning

confidence: 99%

Trachycarpus fortunei H. Wendl. under Winter and Summer Conditions

Neményi¹,

Georgakopoulos

Kissimon³

et al. 1999

Zeitschrift Für Naturforschung C

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A study was conducted to analyze the contribution of high irradiance and resulting photo inhibition to the decline in net photosynthesis in the leaves of palm Trachycarpus fortunei during summer and winter as well as at normal growth and low temperatures in field and laboratory conditions, respectively. Fluorescence induction measurements indicated that there was a 10% decrease in the F v/Fm ratio in field conditions at midday during both summer and winter, due to the relatively low intensity of incident light resulting from the partial leaf segment folding. Fluorescence parameters completely recovered by the evening hours. In summer the midday decay was due to the decrease of F m which probably represents a rapidly reversible component of photoinhibition by the protective down-regulation of PSII mediated by the xanthophyll cycle. In winter, however, the initial Fv/Fm ratio was 40% less than as measured in summer and its midday decline was associated with the decrease of Fv indicating the partial inactivation of PS II. TTie net C 0 2 assimilation rate followed the pattern of the Fv/Fm ratio but it could not recover due to the stomatal closure after midday. Comparing the fluorescence and gas exchange measurements we have concluded that the photoinhibition of T. fortunei represented by the F v/Fm ratio changes is a regulatory adjustment of PS II effi ciency to limiting carbon utilization and to limiting carbon availability imposed by stomatal closure. Leaves photoinhibited under laboratory conditions at growth temperature showed a substantial decrease of 50% in the F v/Fm ratio due to the perpendicular exposure, but no apparent changes in D[ protein content could be detected. Phytotron grown plants exposed to cold stress (6 °C) and low irradiance (250 [.imol m~2 s_1) under laboratory conditions showed a time related but much slower continuous decrease in F v/Fm ratio. After high irradi ance the recovery kinetics in the dark at normal growth temperature (28 °C) strongly de pended on the extent of the photoinhibition, while after low irradiance complete recovery occurred in 12 hours irrespective of the initial Fv/Fm value, independently from the time of cold treatment, indicating that at low light and cold treatments only reversible inactive PS IIs were formed.

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Thermoluminescence characteristics of granal and agranal chloroplasts of maize

Cited by 37 publications

References 12 publications

Acridones: a chemically new group of protonophores.

Acridones: a chemically new group of protonophores.

Untitled

Trachycarpus fortunei H. Wendl. under Winter and Summer Conditions

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