Time filter

Source Type

Mathur S.,Devi Ahilya University | Allakhverdiev S.I.,RAS Institute of Basic Biological Problems | Jajoo A.,Devi Ahilya University
Biochimica et Biophysica Acta - Bioenergetics | Year: 2011

This study demonstrates the effect of high temperature stress on the heterogeneous behavior of PSII in Wheat (Triticum aestivum) leaves. Photosystem II in green plant chloroplasts displays heterogeneity both in the composition of its light harvesting antenna i.e. on the basis of antenna size (α, β and γ centers) and in the ability to reduce the plastoquinone pool i.e. the reducing side of the reaction centers (Q B-reducing centers and Q B-non-reducing centers). Detached wheat leaves were subjected to high temperature stress of 35°C, 40°C and 45°C. The chlorophyll a (Chl a) fluorescence transient were recorded in vivo with high time resolution and analyzed according to JIP test which can quantify PS II behavior using Plant efficiency analyzer (PEA). Other than PEA, Biolyzer HP-3 software was used to evaluate different types of heterogeneity in wheat leaves. The results revealed that at high temperature, there was a change in the relative amounts of PSII α, β and γ centers. As judged from the complementary area growth curve, it seemed that with increasing temperature the PSII α and PSII β centers increased at the expense of PSII γ centers. The reducing side heterogeneity was also affected as shown by an increase in the number of Q B-non-reducing centers at high temperatures. The reversibility of high temperature induced damage on PSII heterogeneity was also studied. Antenna size heterogeneity was recovered fully up to 40°C while reducing side heterogeneity showed partial recovery at 40°C. An irreversible damage to both the types of heterogeneity was observed at 45°C. The work is a significant contribution to understand the basic mechanism involved in the adaptation of crop plants to stress conditions. © 2010 Elsevier B.V.

Murata N.,Japan National Institute for Basic Biology | Allakhverdiev S.I.,RAS Institute of Basic Biological Problems | Nishiyama Y.,Saitama University
Biochimica et Biophysica Acta - Bioenergetics | Year: 2012

Photoinhibition of photosystem II (PSII) occurs when the rate of light-induced inactivation (photodamage) of PSII exceeds the rate of repair of the photodamaged PSII. For the quantitative analysis of the mechanism of photoinhibition of PSII, it is essential to monitor the rate of photodamage and the rate of repair separately and, also, to examine the respective effects of various perturbations on the two processes. This strategy has allowed the re-evaluation of the results of previous studies of photoinhibition and has provided insight into the roles of factors and mechanisms that protect PSII from photoinhibition, such as catalases and peroxidases, which are efficient scavengers of H2O2; α-tocopherol, which is an efficient scavenger of singlet oxygen; non-photochemical quenching, which dissipates excess light energy that has been absorbed by PSII; and the cyclic and non-cyclic transport of electrons. Early studies of photoinhibition suggested that all of these factors and mechanisms protect PSII against photodamage. However, re-evaluation by the strategy mentioned above has indicated that, rather than protecting PSII from photodamage, they stimulate protein synthesis, with resultant repair of PSII and mitigation of photoinhibition. This article is part of a Special Issue entitled: Photosynthesis Research for Sustainability: from Natural to Artificial. © 2011 Elsevier B.V. All rights reserved.

Wiechen M.,Monash University | Najafpour M.M.,Institute for Advanced Studies in Basic Sciences | Allakhverdiev S.I.,RAS Institute of Basic Biological Problems | Spiccia L.,Monash University
Energy and Environmental Science | Year: 2014

The Oxygen Evolving Complex (OEC) in photosystem II, a cluster that contains four manganese and one calcium ions bridged by five oxygen atoms in a distorted chair like arrangement, carries out the biological oxidation of water during photosynthesis. Since this is the only cluster established in biological water oxidation catalysis, efforts have been made to develop synthetic systems that mimic its structure, properties and water oxidation activity. This perspective provides a brief overview of the current structural and mechanistic understanding of the OEC in photosystem II. It then compares the structural features of this complex with those of manganese oxide water oxidation catalysts and discusses structure-function relationships that inform the development of new catalysts. The identified features should be considered when endeavouring to design manganese oxide, and other metal oxide, catalysts with optimal activity that can ultimately be integrated into photo-electrochemical devices to achieve solar water-splitting. © The Royal Society of Chemistry 2014.

Soltamov V.A.,RAS Ioffe Physical - Technical Institute | Soltamova A.A.,RAS Ioffe Physical - Technical Institute | Baranov P.G.,RAS Ioffe Physical - Technical Institute | Proskuryakov I.I.,RAS Institute of Basic Biological Problems
Physical Review Letters | Year: 2012

We report the realization of the optically induced inverse population of the ground-state spin sublevels of the silicon vacancies (V Si) in silicon carbide (SiC) at room temperature. The data show that the probed silicon vacancy spin ensemble can be prepared in a coherent superposition of the spin states. Rabi nutations persist for more than 80μs. Two opposite schemes of the optical alignment of the populations between the ground-state spin sublevels of the silicon vacancy upon illumination with unpolarized light are realized in 4H- and 6H-SiC at room temperature. These altogether make the silicon vacancy in SiC a very favorable defect for spintronics, quantum information processing, and magnetometry. © 2012 American Physical Society.

Markelova N.Y.,RAS Institute of Basic Biological Problems
International Journal of Hygiene and Environmental Health | Year: 2010

Bacteria of the genus of Bdellovibrio are highly motile Gram-negative predators of other Gram-negative bacteria causing lysis of their prey. Here we report results of studies on the interactions of Bdellovibrio with species of Alcaligenes, Campylobacter, Erwinia, Escherichia, Helicobacter, Pseudomonas, Legionella, and Shigella in agar lower, liquid media and cells attached to a surface. Helicobacter pylori was studied employing both actively growing and viable but nonculturable (VBNC) cells. The majority of the bacterial strains tested were found to be susceptible to Bdellovibrio. A significant observation was that Bdellovibrio attacked both actively growing and VBNC H. pylori, that phenomenon has never been reported. The results indicate that bdellovibrios have potential as biocontrol agents. © 2010 Elsevier GmbH.

Kaminskaya O.P.,RAS Institute of Basic Biological Problems | Shuvalov V.A.,RAS Institute of Basic Biological Problems
Biochimica et Biophysica Acta - Bioenergetics | Year: 2013

In photosystem II membrane fragments with oxidized cytochrome (Cyt) b559 reduction of Cyt b559 by plastoquinol formed in the membrane pool under illumination and by exogenous decylplastoquinol added in the dark was studied. Reduction of oxidized Cyt b559 by plastoquinols proceeds biphasically comprising a fast component with a rate constant higher than (10 s)- 1, named phase I, followed by a slower dark reaction with a rate constant of (2.7 min)- 1 at pH 6.5, termed phase II. The extents of both components of Cyt b559 reduction increased with increasing concentrations of the quinols, with that, maximally a half of oxidized Cyt b559 can be photoreduced or chemically reduced in phase I at pH 6.5. The photosystem II herbicide dinoseb but not 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) competed with the quinol reductant in phase I. The results reveal that the two components of the Cyt b559 redox reaction reflect two redox equilibria attaining in different time domains. One-electron redox equilibrium between oxidized Cyt b559 and the photosystem II-bound plastoquinol is established in phase I of Cyt b559 reduction. Phase II is attributed to equilibration of Cyt b559 redox forms with the quinone pool. The quinone site involved in phase I of Cyt b559 reduction is considered to be the site regulating the redox potential of Cyt b559 which can accommodate quinone, semiquinone and quinol forms. The properties of this site designated here as QD clearly suggest that it is distinct from the site QC found in the photosystem II crystal structure. © 2013 Elsevier B.V.

Najafpour M.M.,Institute for Advanced Studies in Basic Sciences | Allakhverdiev S.I.,RAS Institute of Basic Biological Problems
International Journal of Hydrogen Energy | Year: 2012

For hydrogen production by water splitting, the water oxidation half reaction is overwhelmingly rate limiting and needs high over-voltage (∼1 V), which results in low conversion efficiencies when working at current densities required. At this high voltage, other chemicals will be also oxidized and this would be environmentally unacceptable for large-scale H 2 production. In past few years, there has been a tremendous surge in research on the synthesis of various metal compounds aimed at the simulating water oxidizing complex of Photosystem II. Particular attention has been given to the manganese compounds not only because manganese has been used by Nature to oxidize water but also because manganese is cheap and environmentally friendly. In this review, we focus on manganese compounds as functional models of the water oxidizing complex of Photosystem II for hydrogen production via water splitting. © 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Allakhverdiev S.I.,RAS Institute of Basic Biological Problems
International Journal of Hydrogen Energy | Year: 2012

It is clear that three of the great challenges facing humanity in the 21st century are energy supply, climate change, and global food security. Although global energy demand is expected to continue to increase, the availability of low cost energy will continue to diminish. Coupled with increasing concerns about climate change due to CO 2 release from the combustion of fossil fuels, there is now an urgent need to develop clean and renewable energy system for the hydrogen production. This special issue contains selected papers on photosynthetic and biomimetic hydrogen production presented at the International Conference "Photosynthesis Research for Sustainability-2011", that was held in Baku, Azerbaijan, during July 24-30, 2011, with the sponsorship of the International Society of Photosynthesis Research (ISPR) and of the International Association for Hydrogen Energy (IAHE). This issue is intended to provide to our readers recent information on the photosynthetic and biomimetic hydrogen production. The web site of this international conference is at: http://www.photosynthesis2011.cellreg.org. At this conference, awards were given to nine young investigators. We have included here some photographs to show the pleasant ambiance at this conference. (Also see http://www.photosynthesis2011. cellreg.org/Photos.php and http://www.life.illinois.edu/govindjee/g/Photo/Baku. html for some additional photographs). We invite the readers to the next conference on "Photosynthesis Research for Sustainability-2013" to be held in May or June 2013, in Baku, Azerbaijan. Information will be posted at: http://www.photosynthesis2013.cellreg.org. © 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Ivanov B.N.,RAS Institute of Basic Biological Problems
Biochemistry (Moscow) | Year: 2014

Experimental data concerning the role of ascorbic acid in both the maintenance of photosynthesis and in the protection of the photosynthetic apparatus against reactive oxygen species and photoinhibition are reviewed. The function of ascorbic acid as an electron donor in the "Krasnovsky reaction", as well as its physiological role as a donor to components of the photosynthetic electron transport chain, which was first studied by A. A. Krasnovsky in the 1980s, is discussed. Data on the content and transport of ascorbic acid in plant cells and chloroplasts are presented. © 2014 Pleiades Publishing, Ltd.

Light-dependent binding of labeled ADP and ATP to noncatalytic sites of chloroplast ATP synthase and the effect of light-exposed thylakoid membrane preincubation with ADP or ATP on ATPase activity were studied. ADP binding during the preincubation was shown to inactivate the chloroplast ATPase, whereas ATP binding caused its activation. The rate and equilibrium constants of ATPase inactivation and activation were close to those of ADP and ATP binding to a noncatalytic site, with Kd values of 38 and 33 μM, respectively. It is suggested that ADP- or ATP-binding to one of the noncatalytic sites affects the ATPase activity of chloroplast ATP synthase through a mechanism that modulates tightness of ADP binding to a catalytic site. © 2010 Springer Science+Business Media B.V.

Loading RAS Institute of Basic Biological Problems collaborators
Loading RAS Institute of Basic Biological Problems collaborators