Reduced levels of cytochrome b 6/f in transgenic tobacco increases the excitation pressure on Photosystem II without increasing sensitivity to photoinhibition in vivo

1996 ◽  
Vol 50 (2) ◽  
pp. 159-169 ◽  
Author(s):  
Vaughan Hurry ◽  
Jan M. Anderson ◽  
Murray R. Badger ◽  
G. Dean Price
Keyword(s):  
Photosystem Ii ◽  
Transgenic Tobacco ◽  
Cytochrome B ◽  
Excitation Pressure

Excitation pressure regulates the activation energy for recombination events in the photosystem II reaction centres of Chlamydomonas reinhardtii

2007 ◽  
Vol 85 (6) ◽  
pp. 721-729 ◽  
Author(s):  
Tessa Pocock ◽  
P. V. Sane ◽  
S. Falk ◽  
N. P.A. Hüner
Keyword(s):  
Activation Energy ◽  
Photosystem Ii ◽  
Redox Potential ◽  
Chlamydomonas Reinhardtii ◽  
Reaction Center ◽  
Growth Conditions ◽  
High Irradiance ◽  
Reaction Centres ◽  
Excitation Pressure

Using in vivo thermoluminescence, we examined the effects of growth irradiance and growth temperature on charge recombination events in photosystem II reaction centres of the model green alga Chlamydomonas reinhardtii. We report that growth at increasing irradiance at either 29 or 15 °C resulted in comparable downward shifts in the temperature peak maxima (TM) for S2QB– charge pair recombination events, with minimal changes in S2QA– recombination events. This indicates that such growth conditions decrease the activation energy required for S2QB– charge pair recombination events with no concomitant change in the activation energy for S2QA– recombination events. This resulted in a decrease in the ΔTM between S2QA– and S2QB– recombination events, which was reversible when shifting cells from low to high irradiance and back to low irradiance at 29 °C. We interpret these results to indicate that the redox potential of QB was modulated independently of QA, which consequently narrowed the redox potential gap between QA and QB in photosystem II reaction centres. Since a decrease in the ΔTM between S2QA– and S2QB– recombination events correlated with growth at increasing excitation pressure, we conclude that acclimation to growth under high excitation pressure narrows the redox potential gap between QA and QB in photosystem II reaction centres, enhancing the probability for reaction center quenching in C. reinhardtii. We discuss the molecular basis for the modulation of the redox state of QB, and suggest that the potential for reaction center quenching complements antenna quenching via the xanthophyll cycle in the photoprotection of C. reinhardtii from excess light.

Changes in the Oxidation State of Cytochrome B-559 and Tyrosine-D During in Vivo Photoactivation of Photosystem II

1998 ◽  
pp. 1097-1100
Author(s):  
Ann Magnuson ◽  
Maria Rova ◽  
Fikret Mamedov ◽  
Per-Olof Fredriksson ◽  
Stenbjörn Styringl
Keyword(s):  
Photosystem Ii ◽  
Oxidation State ◽  
Cytochrome B ◽  
Tyrosine D

Tandem gene amplification restores photosystem II accumulation in cytochrome b 559 mutants of cyanobacteria

2021 ◽  
Author(s):  
Yi‐Fang Chiu ◽  
Han‐Yi Fu ◽  
Petra Skotnicová ◽  
Kung‐Min Lin ◽  
Josef Komenda ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Gene Amplification ◽  
Cytochrome B

In vivo analysis of sequences necessary for CBP1-dependent accumulation of cytochrome b transcripts in yeast mitochondria

1993 ◽  
Vol 13 (7) ◽  
pp. 4203-4213
Author(s):  
T M Mittelmeier ◽  
C L Dieckmann
Keyword(s):  
Cytochrome B ◽  
Mitochondrial Gene ◽  
Microprojectile Bombardment ◽  
Nuclear Gene ◽  
State Level ◽  
Transcription Unit ◽  
Endonucleolytic Cleavage ◽  
In Vivo Analysis ◽  
Nucleotide Region

In Saccharomyces cerevisiae, cytochrome b, an essential component of the respiratory chain, is encoded by the mitochondrial gene cob. The cob transcription unit includes the tRNA(Glu) gene from positions -1170 to -1099 relative to the cob ATG at +1. The initial tRNA(Glu)-cob transcript undergoes several processing events, including removal of tRNA(Glu) and production of the mature 5' end of cob mRNA at nucleotide -954. The nuclear gene product CBP1 is specifically required for the accumulation of cob mRNA. In cbp1 mutant strains, cob transcripts are not detectable by Northern (RNA) blot analysis, but the steady-state level of tRNA(Glu) is similar to that of wild type. The results of a previous study led to the conclusion that a 400-nucleotide region just downstream of tRNA(Glu) is sufficient for CBP1 function. In the present study, the microprojectile bombardment method of mitochondrial transformation was used to introduce deletions within this region of cob. The analysis of cob transcripts in strains carrying the mitochondrial deletion genomes indicates that a 63-nucleotide sequence that encompasses the cleavage site at -954 is sufficient both for CBP1 function and for correct positioning of the cleavage. Furthermore, the data indicate that CBP1 prevents the degradation of unprocessed cob transcripts produced by endonucleolytic cleavage at the 3' end of tRNA(Glu).

scholarly journals Soil Application of Effective Microorganisms (EM) Maintains Leaf Photosynthetic Efficiency, Increases Seed Yield and Quality Traits of Bean (Phaseolus vulgaris L.) Plants Grown on Different Substrates

2019 ◽  
Vol 20 (9) ◽  
pp. 2327 ◽  
Author(s):  
Marcello Iriti ◽  
Alessio Scarafoni ◽  
Simon Pierce ◽  
Giulia Castorina ◽  
Sara Vitalini
Keyword(s):  
Phaseolus Vulgaris ◽  
Photosystem Ii ◽  
Sandy Soil ◽  
Photosynthetic Efficiency ◽  
Quality Traits ◽  
Phaseolus Vulgaris L ◽  
Effective Microorganisms ◽  
Yield And Quality ◽  
Bean Plants

EM (effective microorganisms) is a biofertilizer consisting of a mixed culture of potentially beneficial microorganisms. In this study, we investigated the effects of EM treatment on leaf in vivo chlorophyll a fluorescence of photosystem II (PSII), yield, and macronutrient content of bean plants grown on different substrates (nutrient rich substrate vs. nutrient poor sandy soil) in controlled environmental conditions (pot experiment in greenhouse). EM-treated plants maintained optimum leaf photosynthetic efficiency two weeks longer than the control plants, and increased yield independent of substrate. The levels of seed nutritionally-relevant molecules (proteins, lipids, and starch) were only slightly modified, apart from the protein content, which increased in plants grown in sandy soil. Although EM can be considered a promising and environmentally friendly technology for sustainable agriculture, more studies are needed to elucidate the mechanism(s) of action of EM, as well as its efficacy under open field conditions.

Bioenergetics Studies of the Cyanobacterium Anabaena variabilis

1987 ◽  
Vol 42 (11-12) ◽  
pp. 1280-1284 ◽  
Author(s):  
Siegfried Scherer ◽  
Heike Sadowski ◽  
Peter Böger
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Cytochrome B ◽  
Anabaena Variabilis ◽  
Electron Donors ◽  
Free System ◽  
Low Concentrations ◽  
Cyanobacterium Anabaena ◽  
A Cell ◽  
C Complex

A cell-free system exhibiting both photophosphorylation (P/2e= 1) and oxidative phosphoryltion (P/O up to 0.8) is described for the cyanobacterium Anabaena variabilis. NADH ant NADPH were found to be equally effective as electron donors for oxidative phosphorylation. Low concentrations of UHDBT, an inhibitor of the cytochrome b/c complex of mitochondria ant loroplasts, were found to inhibit photosystem-II electron transport reactions, but did not affet the cytochrome b6/f-complex of Anabaena. The inhibition by myxothiazol, antimycin and heptyihydroxyquinoline corroborates the hypothesis that both respiration and photosynthesis share the cytochrome b6/f-complex.

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