Differential action of Hg2+ and Cd2+ on the phycobilisomes and chlorophyll a fluorescence, and photosystem II dependent electron transport in the cyanobacterium Anabaena flos-aquae

BioMetals ◽  
1993 ◽  
Vol 6 (2) ◽  
Author(s):  
D.P. Singh ◽  
S.K. Sharma ◽  
P.S. Bisen
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Chlorophyll A ◽  
Chlorophyll A Fluorescence ◽  
Cyanobacterium Anabaena ◽  
Differential Action

Herbicides which Inhibit Electron Transport or Produce Chlorosis and Their Effect on Chloroplast Development in Radish Seedlings I. Chlorophyll a Fluorescence Transients and Photosystem II Activity

1982 ◽  
Vol 37 (3-4) ◽  
pp. 268-275 ◽  
Author(s):  
K. H. Grumbach
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Chlorophyll A ◽  
Oxygen Evolution ◽  
Chlorophyll A Fluorescence ◽  
Photosynthetic Electron Transport ◽  
Photosystem Ii Activity ◽  
Chlorophyll A Fluorescence Transients ◽  
Radish Seedlings ◽  
Fluorescence Transients

Abstract Diuron and bentazon are very strong inhibitors of the photosynthetic electron transport in isolated radish chloroplasts. The chlorosis producing herbicide SAN 6706 also inhibited the photosystem II dependent oxygen evolution. Aminotriazole had no effect. The inhibitor concentration for 50% inhibition of photosystem II activity was 10-7 m for diuron and 10-4 m for bentazon and SAN 6706 respectively.Diuron and bentazon quenched the chlorophyll a fluorescence transients in isolated radish chloroplasts drastically, while aminotriazole was not effective. It was of particular interest that the bleaching herbicide SAN 6706 inhibited photosystem II dependent oxygen evolution in a similar concentration as bentazon but had no effect on the chlorophyll a-fluorescence transients suggesting that SAN 6706 is not binding to the same site of the electron transport chain as diuron and bentazon.Apart from their direct influence on electron transport in isolated photosynthetically active chloroplasts the photosystem II and bleaching herbicides assayed also strongly affected photosynthesis in radish seedlings that were grown in the presence of the herbicides for a long time. As already obtained using isolated chloroplasts, photosystem II dependent oxygen evolution like the chlorophyll a fluorescence transients were strongly inhibited by the photosystem II herbicides diuron and bentazon. A reduction but no inhibition of photosystem II activity was observed in plants that were grown in the presence of aminotriazole. The pyridazinone SAN 6706 was behaving contradictory. In partly green plants photosystem II activity was still maintained and even higher than in untreated plants while in albinistic plants no photosynthetic activity was detected.

Inhibitory Effect of Crown Compound on Photoelectron Transport Activity of Beet Spinach Thylakoid Membranes

1991 ◽  
Vol 46 (1-2) ◽  
pp. 87-92 ◽  
Author(s):  
S. C. Sabat ◽  
V. Vijayavergiya ◽  
B. C. Tripathy ◽  
Prasanna Mohanty
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Chlorophyll A ◽  
Chlorophyll A Fluorescence ◽  
Thylakoid Membranes ◽  
Dependent Manner ◽  
Transport Activity ◽  
Concentration Dependent Manner ◽  
Variable Yield ◽  
Spinach Thylakoid

Abstract The effect of K-picrate-18-crown-6 (crown) on the photoelectron transport activity of beet spinach thylakoid membranes was investigated. Addition of micromolar concentration of crown to thylakoid preparation inhibited p-benzoquinone, chloride-indophenol, methyl viologen supported Hill activities maximally by 75 per cent in a concentration dependent manner. However, the photosystem I catalyzed reaction remained insensitive to crown suggesting that crown specifically inhibits photosystem II electron transport. Addition of exogenous electron donors like hydroxylamine or diphenylcarbazide failed to restore the crown induced inhibition of photosystem II electron transport and lowering of steady state chlorophyll a fluorescence yield. These observations suggest that crown also inhibits photosystem II catalyzed electron transport after the donation sites of these exogenous donors. Washing of the crown pre-treated thylakoids with isolation buffer, relieved the crown inhibited electron transport activity, indicating that this inhibition is reversible. Furthermore, in hydroxylamine washed thylakoids which are devoid of O2 evolution capacity, the hydroxylamine induced increase in chlorophyll a fluorescence of variable yield was quenched by the addition of crown. These observations suggest that crown affects the oxygen evolution and inhibits at a site close to photosystem II reaction centres.

Research note: Energy partitioning in photosystem II complexes subjected to photoinhibitory treatment

2007 ◽  
Vol 34 (3) ◽  
pp. 214 ◽  
Author(s):  
Dmytro Kornyeyev ◽  
Luke Hendrickson
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Excitation Energy ◽  
Chlorophyll A ◽  
Chlorophyll A Fluorescence ◽  
Photosynthetic Electron Transport ◽  
Energy Partitioning ◽  
Simple Equations

Chlorophyll a fluorescence measured in vivo is frequently used to study the role of different processes influencing the distribution of excitation energy in PSII complexes. Such studies are important for understanding the regulation of photosynthetic electron transport. However, at the present time, there is no unified methodology to analyse the energy partitioning in PSII. In this article, we critically assess several approaches recently developed in this area of research and propose new simple equations, which can be used for de-convolution of non-photochemical energy quenching in PSII complexes.

Picrate Salt of a Cyclic Polyether, 18-Crown-6 (Ca-picrate-18-crown-6), Inhibits the Photosynthetic Electron Transport at the Acceptor Side of Photosystem II

1998 ◽  
Vol 53 (3-4) ◽  
pp. 159-162
Author(s):  
Manoj K. Joshi ◽  
T. S. Desai ◽  
Prasanna Mohanty
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Chlorophyll A ◽  
Chlorophyll A Fluorescence ◽  
Photosynthetic Electron Transport ◽  
Acceptor Side ◽  
Site Of Action ◽  
Fast Chlorophyll A Fluorescence

Abstract It has been demonstrated that cyclic polyether, K -picrate-18-crown-6 inhibited photosyn­ thetic electron transport (Sabat et al., 1991, Z. Naturforsch. 46c , 87-92) . We further analyzed the alterations induced in the fast chlorophyll a fluorescence and thermoluminescence pattern of pea thylakoids by calcium-18-crown-6 (crown-picrate). The results indicate that the site of action of calcium crown-picrate is at the acceptor side of photosystem II.

Characterization of the Inhibition of Photosynthetic Electron Transport in Pea Chloroplasts by the Herbicide 4,6-Dinitro-o-cresol by Comparative Studies with 3-(3,4-Dichlorophenyl)-1,1- dimethylurea

1978 ◽  
Vol 33 (5-6) ◽  
pp. 413-420 ◽  
Author(s):  
J. J. S. van Rensen ◽  
D. Wong ◽  
Govindjee
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Chlorophyll A ◽  
Oxygen Evolution ◽  
Chlorophyll A Fluorescence ◽  
Chlorophyll Concentration ◽  
Fluorescence Emission ◽  
Photosynthetic Electron Transport ◽  
Percent Inhibition ◽  
Mechanism Of Inhibition

An attempt to characterize the mechanism of inhibition of photosynthetic electron transport in isolated pea chloroplasts by the herbicide 4,6-dinitro-o-cresol (DNOC) by a comparison with the effects of 3-(3,4-dichlorophenyl)-1.1-dimethylurea (DCMU) revealed the following: 1.The percent inhibition of oxygen evolution by a given herbicide concentration is the same at various light intensities except at very low intensities where the percent inhibition becomes larger. The same results are obtained with the herbicide DCMU. 2.The concentration of DCMU causing 50% inhibition of oxygen evolution decreases with de­creasing chloroplast (and thus of chlorophyll) concentration. With DNOC, the relative decrease is much less than with DCMU. At the inhibited molecule, there appears to be a cooperative binding of DCMU with two binding sites and a noncooperative binding of DNOC with only one binding site. 3.The chlorophyll a fluorescence induction is influenced by DNOC in the same characteristic way as it is by DCMU: both herbicides cause a faster rise in fluorescence yield than in control chloroplasts, although a higher concentration of the former is required for the same effect. 4.The chlorophyll fluorescence emission spectra at 77 CK show a slight decrease in the bands at 685 and 735 nm, and no or only a very slight decrease at 695 nm upon addition of high con­centrations of either DCMU or DNOC before the onset of illumination. 5.The degree of polarization of chlorophyll a fluorescence is lower after addition of DCMU or DNOC upon excitation by 460 or 660 nm light. It is concluded that, although the chemical structure of DNOC is completely different from that of DCMU, its site and mechanism of inhibition is similar to that of DCMU. Both herbicides inhibit electron transport between the primary electron acceptor of photosystem II and the plastoquinone pool. This causes a closing of the reaction centers of photosystem II. However, the interaction with the inhibited molecule is different for the two herbicides.

scholarly journals Effects of Different Planting Densities on Photosynthesis in Maize Determined via Prompt Fluorescence, Delayed Fluorescence and P700 Signals

Plants ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 276
Author(s):  
Wanying Chen ◽  
Bo Jia ◽  
Junyu Chen ◽  
Yujiao Feng ◽  
Yue Li ◽  
...  
Keyword(s):  
Electron Transport ◽  
Chlorophyll A ◽  
Chlorophyll A Fluorescence ◽  
Electron Transport Chain ◽  
Plant Density ◽  
Photosynthetic Electron Transport ◽  
Planting Density ◽  
Strong Impact ◽  
Photosynthetic Electron Transport Chain ◽  
Transport Chain

The mutual shading among individual field-grown maize plants resulting from high planting density inevitably reduces leaf photosynthesis, while regulating the photosynthetic transport chain has a strong impact on photosynthesis. However, the effect of high planting density on the photosynthetic electron transport chain in maize currently remains unclear. In this study, we simultaneously measured prompt chlorophyll a fluorescence (PF), modulated 820 nm reflection (MR) and delayed chlorophyll a fluorescence (DF) in order to investigate the effect of high planting density on the photosynthetic electron transport chain in two maize hybrids widely grown in China. PF transients demonstrated a gradual reduction in their signal amplitude with increasing planting density. In addition, high planting density induced positive J-step and G-bands of the PF transients, reduced the values of PF parameters PIABS, RC/CSO, TRO/ABS, ETO/TRO and REO/ETO, and enhanced ABS/RC and N. MR kinetics showed an increase of their lowest point with increasing high planting density, and thus the values of MR parameters VPSI and VPSII-PSI were reduced. The shapes of DF induction and decay curves were changed by high planting density. In addition, high planting density reduced the values of DF parameters I1, I2, L1 and L2, and enhanced I2/I1. These results suggested that high planting density caused harm on multiple components of maize photosynthetic electron transport chain, including an inactivation of PSII RCs, a blocked electron transfer between QA and QB, a reduction in PSI oxidation and re-reduction activities, and an impaired PSI acceptor side. Moreover, a comparison between PSII and PSI activities demonstrated the greater effect of plant density on the former.

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.

The polyphasic chlorophyll a fluorescence rise measured under high intensity of exciting light

2006 ◽  
Vol 33 (1) ◽  
pp. 9 ◽  
Author(s):  
Dušan Lazár
Keyword(s):  
Electron Transport ◽  
Chlorophyll A ◽  
Chlorophyll A Fluorescence ◽  
High Intensity ◽  
High Temperature Stress ◽  
Electron Acceptors ◽  
Exciting Light ◽  
Electric Voltage ◽  
Light Gradient ◽  
Fluorescence Rise

Chlorophyll a fluorescence rise caused by illumination of photosynthetic samples by high intensity of exciting light, the O–J–I–P (O–I1–I2–P) transient, is reviewed here. First, basic information about chlorophyll a fluorescence is given, followed by a description of instrumental set-ups, nomenclature of the transient, and samples used for the measurements. The review mainly focuses on the explanation of particular steps of the transient based on experimental and theoretical results, published since a last review on chlorophyll a fluorescence induction [Lazár D (1999) Biochimica et Biophysica Acta 1412, 1–28]. In addition to ‘old’ concepts (e.g. changes in redox states of electron acceptors of photosystem II (PSII), effect of the donor side of PSII, fluorescence quenching by oxidised plastoquinone pool), ‘new’ approaches (e.g. electric voltage across thylakoid membranes, electron transport through the inactive branch in PSII, recombinations between PSII electron acceptors and donors, electron transport reactions after PSII, light gradient within the sample) are reviewed. The K-step, usually detected after a high-temperature stress, and other steps appearing in the transient (the H and G steps) are also discussed. Finally, some applications of the transient are also mentioned.

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