scholarly journals Electron Flow between Photosystem II and Oxygen in Chloroplasts of Photosystem I-deficient Algae Is Mediated by a Quinol Oxidase Involved in Chlororespiration

2000 ◽  
Vol 275 (23) ◽  
pp. 17256-17262 ◽  
Author(s):  
Laurent Cournac ◽  
Kevin Redding ◽  
Jacques Ravenel ◽  
Dominique Rumeau ◽  
Eve-Marie Josse ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Photosystem I ◽  
Electron Flow ◽  
Quinol Oxidase

DCMU-Induced Fluorescence Changes and Photodestruction of Pigments Associated with an Inhibition of Photosystem I Cyclic Electron Flow

1984 ◽  
Vol 39 (5) ◽  
pp. 351-353 ◽  
Author(s):  
Stuart M. Ridley ◽  
Peter Horton
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Photosystem I ◽  
Dose Response ◽  
Electron Flow ◽  
Cyclic Electron Flow ◽  
Cyclic Flow ◽  
Working Hypothesis ◽  
Dose Responses

Diuron (DCMU) induces the photodestruction of pigments, which is the initial herbicidal symptom. As a working hypothesis, it is proposed that this symptom can only be produced when the herbicide dose is sufficiently high to inhibit not only photosystem II electron transport almost completely, but also inhibit (through over oxidation) the natural cyclic electron flow associated with photosystem I as well. Using freshly prepared chloroplasts, studies of DCMU-induced fluorescence changes, and dose responses for inhibition of electron transport, have been compared with a dose response for the photodestruction of pigments in chloroplasts during 24 h illumination. Photodestruction of pigments coincides with the inhibition of cyclic flow.

The Effect of Deoxycholate-Treatment to the Photoreactions of the Active Pigments in Photosynthesis

1976 ◽  
Vol 31 (1-2) ◽  
pp. 64-67 ◽  
Author(s):  
Günter Döring
Keyword(s):  
Photosystem Ii ◽  
Chlorophyll A ◽  
Photosystem I ◽  
Electron Flow ◽  
Heavy Fraction ◽  
Sodium Ascorbate ◽  
Linear Electron ◽  
System P ◽  
Heat Treated ◽  
Donor System

Abstract In the heavy fraction of deoxycholate-treated spinach chloroplasts the chlorophyll an activity is high and the chlorophyll aI activity is low when no artificial electron donor is added. The addition of the photosystem I donor system N-methyl-phenazonium sulphate plus sodium ascorbate (PMS + Asc) leads to a complete reactivation of the chlorophyll aI reaction. The addition of the photo­system II donor system p-benzohydroquinone plus sodium ascorbate (HQ + Asc) leads to an inhibition of the chlorophyll aII activity. From these results we conclude: 1. Besides an interruption of the linear electron flow between the two photosystems deoxycholate-treatment leads to a block of the electron flow from water to photosystem II. 2. In deoxycholate-treated chloroplasts the linear electron flow in photosystem II just like in Triswashed, heat-treated or aged chloroplasts, is replaced by a cyclic one.

scholarly journals Evidence for thylakoid membrane fusion during zygote formation in Chlamydomonas reinhardtii.

1991 ◽  
Vol 114 (5) ◽  
pp. 905-915 ◽  
Author(s):  
B Baldan ◽  
J Girard-Bascou ◽  
F A Wollman ◽  
J Olive
Keyword(s):  
Photosystem Ii ◽  
Chlamydomonas Reinhardtii ◽  
Photosystem I ◽  
Thylakoid Membrane ◽  
De Novo ◽  
Electron Flow ◽  
Thylakoid Membranes ◽  
Structural Basis ◽  
Zygote Formation ◽  
Thin Sections

To understand whether fusions of thylakoid membranes from the parental chloroplasts occurred during zygote formation in Chlamydomonas reinhardtii, we performed an ultrastructural analysis of the zygotes produced by crossing mutants lacking photosystem I or II protein complexes, in the absence of de novo chloroplast protein synthesis. Thylakoid membranes from each parent could be distinguished on thin sections due to their organization in "supergrana" in mutants lacking photosystem I centers, by freeze-fracturing due to the absence of most of the exoplasmic-face (EF) particles in mutants lacking photosystem II centers, by immunocytochemistry using antibodies directed against photosystem II subunits. We demonstrate that a fusion of the thylakoid membranes occurred during zygote formation approximately 15 h after mating. These fusions allowed a lateral redistribution of the thylakoid membrane proteins. These observations provide the structural basis for the restoration of photosynthetic electron flow in the mature zygote that we observed in fluorescence induction experiments.

scholarly journals Photosystem II Is More Sensitive than Photosystem I to Al3+ Induced Phytotoxicity

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1772 ◽  
Author(s):  
Julietta Moustaka ◽  
Georgia Ouzounidou ◽  
Ilektra Sperdouli ◽  
Michael Moustakas
Keyword(s):  
Photosystem Ii ◽  
Photosystem I ◽  
Triticum Turgidum ◽  
Electron Flow ◽  
Acid Soils ◽  
Growth Conditions ◽  
Superior Performance ◽  
Ionic Form ◽  
Crop Species ◽  
Excitation Pressure

Aluminium (Al) the most abundant metal in the earth’s crust is toxic in acid soils (pH < 5.5) mainly in the ionic form of Al3+ species. The ability of crops to overcome Al toxicity varies among crop species and cultivars. Here, we report for a first time the simultaneous responses of photosystem II (PSII) and photosystem I (PSI) to Al3+ phytotoxicity. The responses of PSII and PSI in the durum wheat (Triticum turgidum L. cv. ‘Appulo E’) and the triticale (X Triticosecale Witmark cv. ‘Dada’) were evaluated by chlorophyll fluorescence quenching analysis and reflection spectroscopy respectively, under control (−Al, pH 6.5) and 148 μM Al (+Al, pH 4.5) conditions. During control growth conditions the high activity of PSII in ‘Appulo E’ led to a rather higher electron flow to PSI, which induced a higher PSI excitation pressure in ‘Appulo E’ than in ‘Dada’ that presented a lower PSII activity. However, under 148 μM Al the triticale ‘Dada’ presented a lower PSII and PSI excitation pressure than ‘Appulo E’. In conclusion, both photosystems of ‘Dada’ displayed a superior performance than ‘Appulo E’ under Al exposure, while in both cultivars PSII was more affected than PSI from Al3+ phytotoxicity.

Effect of an Antiserum to a Thylakoid Membrane Polypeptide on the Primary Photoreaction of Photosystem II

1976 ◽  
Vol 31 (9-10) ◽  
pp. 594-600 ◽  
Author(s):  
Georg H. Schmid ◽  
Gernot Renger ◽  
Michael Gläser ◽  
Friederike Koenig ◽  
Alfons Radunz ◽  
...  
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Photosystem I ◽  
Electron Flow ◽  
Primary Electron ◽  
Hill Reaction ◽  
Ps Ii ◽  
Absorption Change ◽  
Oxygen Evolving ◽  
The Hill

Abstract As was described previously, an antiserum to polypeptide 11000 inhibited photosynthetic elec­tron transport on the oxygen evolving side of photosystem II. The effect of the antiserum on chloro­plasts from two tobacco mutants also clearly showed that the inhibition site is on the photosystem II-side of the electron transport chain. One of the two tobacco mutants lades the oxygen evolving capacity but exhibits some electron transport with tetramethyl benzidine, an artificial donor to PS II. In this mutant electron transport was barely inhibited. The effect of the antiserum on the primary photoevents showed that the initial amplitude of the absorption change of chlorophyll an at 690 nm and that of the primary electron acceptor X320 at 334 nm both diminished in the presence of the antiserum. Both signals were restored upon addition of diphenylcarbazide another artificial donor to photosystem II. Comparison of the degree of inhibition on the amplitudes of the fast and slow components of the 690 nm absorption change with the manometrically measured inhibition of electron transport shows that besides a full inactivation of a part of the reaction centers of photosystem II another part apparently mediates a fast cyclic electron flow around photosystem II as reported by Renger and Wolff earlier for tris-treated chloroplasts. Moreover, the antiserum affects the low temperature fluorescence in a way which is opposite to Murata’s effect of the Mg2+ -ion induced inhibition of energy spill-over from photosystem II to photosystem I. The antiserum under the condition in which the Hill reaction is inhibited lowered the 686 nm emission and enhanced the 732 nm emission which indicates an enhanced energy spill-over to photosystem I.

Inhibition of Photosynthetic Electron Transport by Halogenated 4-Hydroxy-pyridines

1985 ◽  
Vol 40 (5-6) ◽  
pp. 391-399 ◽  
Author(s):  
A. Trebst ◽  
B. Depka ◽  
S. M. Ridley ◽  
A. F. Hawkins
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Photosystem I ◽  
Electron Flow ◽  
Essential Element ◽  
Photosynthetic Electron Transport ◽  
Cyclic Electron Flow ◽  
Acceptor Side

Abstract Herbicidal halogen substituted 4-hydroxypyridines are inhibitors of photosynthetic electron flow in isolated thylakoid membranes by interfering with the acceptor side of photosystem II. Tetrabromo-4-hydroxypyridine, the most active compound found, has a pI50-value of 7.6 in the inhibition of oxygen evolution in both the reduction of an acceptor of photosystem I and an acceptor of photosystem II. The new inhibitors displace both metribuzin and ioxynil from the membrane. The 4-hydroxypyridines, like ioxynil, have unimpaired inhibitor potency in Tristreated chloroplasts, whereas the DCMU-type family of herbicides does not. It is suggested that 4-hydroxypyridines are complementary to phenol-type inhibitors, and a common essential element is proposed. The 4-hydroxypyridines do not inhibit photosystem I or non-cyclic electron flow through the cytochrome b/f complex. But they do have a second inhibition site in photosynthetic electron transport since they inhibit ferredoxin-catalyzed cyclic electron flow, indicating an antimycin-like property. A comparison of the in vitro potency of the compounds with the in vivo potency shows no correlation. A major herbicidal mode of action of the group is related to the inhibition of carotenoid synthesis, and access to the chloroplast lamellae in vivo for inhibition of electron transport may be restricted.

Salt Enhances Photosystem I Content and Cyclic Electron Flow via NAD(P)H Dehydrogenase in the Halotolerant Cyanobacterium Aphanothece halophytica

1996 ◽  
Vol 23 (3) ◽  
pp. 321 ◽  
Author(s):  
T Hibino ◽  
BH Lee ◽  
AK Rai ◽  
H Ishikawa ◽  
H Kojima ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Photosystem I ◽  
Electron Flow ◽  
Cyclic Electron Flow ◽  
O2 Evolution ◽  
Aphanothece Halophytica ◽  
Protein Levels ◽  
Photosynthetic O2 Evolution ◽  
Electron Donation ◽  
Halotolerant Cyanobacterium

To uncover the adaptation mechanisms of photosystems for halotolerance, changes in stoichiometry and activity of photosystems in response to changes of salinities were examined in a halotolerant cyanobacterium, Aphanothece halophytica. Photosynthetic O2 evolution was high even at high salinities. O2 evolution activity increased with increasing external concentration of NaCl, reached a maximum at 1.5 M NaCl, and then decreased. Similar salt dependence was observed for photosystem II activity. On the other hand, photosystem I activity increased concomitantly with increase in salinity. Photoacoustic measurements indicated that appreciable energy storage by photosystem I mediated cyclic electron flow at high salinities. Significant electron donation to photosystem I reaction centres through NAD(P)H-dehydrogenase complexes was observed in high salt media. The contents of cytochrome b6/f and photosystem II were almost constant under various salinity conditions, whereas the levels of chlorophyll α, photosystem I, soluble cytochrome c-553, and NAD(P)H-dehydrogenase increased in the cells grown with high salinities. These results indicate that salt specifically induces an increase of protein levels involving cyclic electron flow around photosystem I that may entail an important role for adaptation of Aphanothece halophytica cells to high salinities.

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