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Kalaji H.M.,Warsaw University of Life Sciences | Schansker G.,Avenue des Amazones 2 | Ladle R.J.,Federal University of Alagoas | Goltsev V.,Sofia University | And 25 more authors.
Photosynthesis Research | Year: 2014

The aim of this educational review is to provide practical information on the hardware, methodology, and the hands on application of chlorophyll (Chl) a fluorescence technology. We present the paper in a question and answer format like frequently asked questions. Although nearly all information on the application of Chl a fluorescence can be found in the literature, it is not always easily accessible. This paper is primarily aimed at scientists who have some experience with the application of Chl a fluorescence but are still in the process of discovering what it all means and how it can be used. Topics discussed are (among other things) the kind of information that can be obtained using different fluorescence techniques, the interpretation of Chl a fluorescence signals, specific applications of these techniques, and practical advice on different subjects, such as on the length of dark adaptation before measurement of the Chl a fluorescence transient. The paper also provides the physiological background for some of the applied procedures. It also serves as a source of reference for experienced scientists. © 2014 The Author(s).

Zorina A.,Institute of Plant Physiology | Stepanchenko N.,Institute of Plant Physiology | Novikova G.V.,Institute of Plant Physiology | Sinetova M.,Institute of Plant Physiology | And 9 more authors.
DNA Research | Year: 2011

Serine/threonine protein kinases (STPKs) are the major participants in intracellular signal transduction in eukaryotes, such as yeasts, fungi, plants, and animals. Genome sequences indicate that these kinases are also present in prokaryotes, such as cyanobacteria. However, their roles in signal transduction in prokaryotes remain poorly understood. We have attempted to identify the roles of STPKs in response to heat stress in the prokaryotic cyanobacterium Synechocystis sp. PCC 6803, which has 12 genes for STPKs. Each gene was individually inactivated to generate a gene-knockout library of STPKs. We applied in vitro Ser/Thr protein phosphorylation and phosphoproteomics and identified the methionyl-tRNA synthetase, large subunit of RuBisCO, 6-phosphogluconate dehydrogenase, translation elongation factor Tu, heat-shock protein GrpE, and small chaperonin GroES as the putative targets for Ser/Thr phosphorylation. The expressed and purified GroES was used as an external substrate to screen the protein extracts of the individual mutants for their Ser/Thr kinase activities. The mutants that lack one of the three protein kinases, SpkC, SpkF, and SpkK, were unable to phosphorylate GroES in vitro, suggesting possible interactions between them towards their substrate. Complementation of the mutated SpkC, SpkF, and SpkK leads to the restoration of the ability of cells to phosphorylate the GroES. This suggests that these three STPKs are organized in a sequential order or a cascade and they work one after another to finally phosphorylate the GroES. © 2011 The Author.

News Article | December 21, 2016

You were born in 1914 and went to school in London. What sparked your interest in ecology? At St Paul’s School, a very good teacher led me from an earlier interest in chemistry into biology. Then at Imperial College London, Botany seemed a stronger department than Zoology. A PhD was a natural progression from the first degree. Some support was available and no jobs were clearly in prospect. You completed your PhD in 1941, during the second world war. What was that like? When the war started I was given a full-time position in the Research Institute of Plant Physiology, on secondment to East Malling Research Station, where I was located throughout the war years. In my spare time I wrote my PhD thesis. At East Malling the scientists were working on horticulture and plant breeding. Did this get you out of conscription? Not only was I exempt from conscription – I was not allowed to join the Forces. I did join the Home Guard but that was undemanding. My work at East Malling was concerned with optimum use of fertilisers and hence with maximising food production. As a scientist, did you have German colleagues before the war? I don’t remember contacts with German colleagues, but before the war I had travelled extensively in northern Europe, and in 1936 I spent a month in Dortmund, Germany, with a Nazi family. How did you feel when war broke out? I regarded the war as defensive, a fight against fascism. Did some part of you wish you could join up and fight? Exclusion from the armed forces was fully acceptable – I took it as a matter of course. How about family life or marriage? Family life started for me in 1940 when I married Veronica. I had a son with Veronica, and two children by my second marriage. I have 12 grandchildren, and 16 great grandchildren so far. Did your parents live to a great age? Have you thought about your genetics and how that might have contributed to your longevity? My mother’s family commonly lived to 90. I would say: To keep alive, keep active. Yes, genetics helps.  But I think by the end of this century centenarians may be two a penny. After the war you worked in Ghana, before it achieved independence from Britain. What was that like? I lived in Tafo, in a house provided by the Colonial Service. I paid a “cook-steward” to look after it.   The nearest town was Koforidua, and opportunities to visit there came most weeks. At Tafo there was a club house, with tennis (which I used) and golf (which I did not). My main project was to study the need of cocoa for shade. Relations with local people were good.  The limited resources compared with England did not worry me. You’ve settled in Australia, how did that come about? In 1948 and again in 1974, I came to Australia for particular jobs. I like Perth’s climate, it’s fairly good, but I would prefer not to have a winter. Do you worry about the future? I am very pessimistic. It is too late to take effective action on climate change.  At least as important is human population, which will increase to 10 billion by the end of the century. Any advice for younger scientists? Keep aware of the history of your field - the decline of libraries makes it easy to forget.

PubMed | RAS Timiryazev Institute of Plant Physiology, RAS A.N. Bach Institute of Biochemistry, Moscow State University, Institute of Plant Physiology and 2 more.
Type: Journal Article | Journal: Biophysical journal | Year: 2017

Orange carotenoid protein (OCP), responsible for the photoprotection of the cyanobacterial photosynthetic apparatus under excessive light conditions, undergoes significant rearrangements upon photoconversion and transits from the stable orange to the signaling red state. This is thought to involve a 12- translocation of the carotenoid cofactor and separation of the N- and C-terminal protein domains. Despite clear recent progress, the detailed mechanism of the OCP photoconversion and associated photoprotection remains elusive. Here, we labeled the OCP of Synechocystis with tetramethylrhodamine-maleimide (TMR) and obtained a photoactive OCP-TMR complex, the fluorescence of which was highly sensitive to the protein state, showing unprecedented contrast between the orange and red states and reflecting changes in protein conformation and the distances from TMR to the carotenoid throughout the photocycle. The OCP-TMR complex was sensitive to the light intensity, temperature, and viscosity of the solvent. Based on the observed Frster resonance energy transfer, we determined that upon photoconversion, the distance between TMR (donor) bound to a cysteine in the C-terminal domain and the carotenoid (acceptor) increased by 18, with simultaneous translocation of the carotenoid into the N-terminal domain. Time-resolved fluorescence anisotropy revealed a significant decrease of the OCP rotation rate in the red state, indicating that the light-triggered conversion of the protein is accompanied by an increase of its hydrodynamic radius. Thus, our results support the idea of significant structural rearrangements of OCP, providing, to our knowledge, new insights into the structural rearrangements of OCP throughout the photocycle and a completely novel approach to the study of its photocycle and non-photochemical quenching. We suggest that this approach can be generally applied to other photoactive proteins.

Sass L.,Institute of Plant Physiology | Majer P.,Institute of Plant Physiology | Hideg E.,University of Pécs
Methods in Molecular Biology | Year: 2012

Computer analysis of digital photographic images provides fast, high-throughput screening of leaf pigmentation. Pixel-by-pixel conversion of red, green, blue (RGB) parameters to hue, saturation, value (HSV) showed that Hue values were proportional to total chlorophyll, offering an alternative to photometric analysis of leaf extracts. This is demonstrated using tobacco leaves with various chlorophyll contents due to senescence but shows the possibility of applications in studies of stress conditions accompanied by chlorophyll loss. © 2012 Springer Science+Business Media, LLC.

Vahabi K.,Institute of Plant Physiology | Camehl I.,Institute of Plant Physiology | Sherameti I.,Institute of Plant Physiology | Oelmuller R.,Institute of Plant Physiology
Plant signaling & behavior | Year: 2013

The endophytic fungus Piriformospora indica colonizes the roots of many plant species including Arabidopsis and promotes their performance, biomass, and seed production as well as resistance against biotic and abiotic stress. Imbalances in the symbiotic interaction such as uncontrolled fungal growth result in the loss of benefits for the plants and activation of defense responses against the microbe. We exposed Arabidopsis seedlings to a dense hyphal lawn of P. indica. The seedlings continue to grow, accumulate normal amounts of chlorophyll, and the photosynthetic parameters demonstrate that they perform well. In spite of high fungal doses around the roots, the fungal material inside the roots was not significantly higher when compared with roots that live in a beneficial symbiosis with P. indica. Fifteen defense- and stress-related genes including PR2, PR3, PAL2, and ERF1 are only moderately upregulated in the roots on the fungal lawn, and the seedlings did not accumulate H2O2/radical oxygen species. However, accumulation of anthocyanin in P. indica-exposed seedlings indicates stress symptoms. Furthermore, the jasmonic acid (JA) and jasmonic acid-isoleucine (JA-Ile) levels were increased in the roots, and consequently PDF1.2 and a newly characterized gene for a 2-oxoglurate and Fe2+ -dependent oxygenase were upregulated more than 7-fold on the dense fungal lawn, in a JAR1- and EIN3-dependent manner. We conclude that growth of A. thaliana seedlings on high fungal doses of P. indica has little effect on the overall performance of the plants although elevated JA and JA-Ile levels in the roots induce a mild stress or defense response.

Sass L.,Institute of Plant Physiology
Methods in molecular biology (Clifton, N.J.) | Year: 2012

Computer analysis of digital photographic images provides fast, high-throughput screening of leaf pigmentation. Pixel-by-pixel conversion of red, green, blue (RGB) parameters to hue, saturation, value (HSV) showed that Hue values were proportional to total chlorophyll, offering an alternative to photometric analysis of leaf extracts. This is demonstrated using tobacco leaves with various chlorophyll contents due to senescence but shows the possibility of applications in studies of stress conditions accompanied by chlorophyll loss.

PubMed | Institute of Plant Physiology
Type: Journal Article | Journal: Photosynthesis research | Year: 2013

The influence of UV-B irradiation on photosynthetic oxygen evolution by isolated spinach thylakoids has been investigated using thermoluminescence measurements. The thermoluminescence bands arising from the S2QB (-) (B band) and S2QA (-) (Q band) charge recombination disappeared with increasing UV-B irradiation time. In contrast, the C band at 50C, arising from the recombination of QA (-) with an accessory donor of Photosystem II, was transiently enhanced by the UV-B irradiation. The efficiency of DCMU to block QA to QB electron transfer decreased after irradiation as detected by the incomplete suppression of the B band by DCMU. The flash-induced oscillatory pattern of the B band was modified in the UV-B irradiated samples, indicating a decrease in the number of centers with reduced QB. Based on the results of this study, UV-B irradiation is suggested to damage both the donor and acceptor sides of Photosystem II. The damage of the water-oxidizing complex does not affect a specific S-state transition. Instead, charge stabilization is enhanced on an accessory donor. The acceptor-side modifications decrease the affinity of DCMU binding. This effect is assumed to reflect a structural change in the QB/DCMU binding site. The preferential loss of dark stable QB (-) may be related to the same structural change or could be caused by the specific destruction of reduced quinones by the UV-B light.

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