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https://www.readbyqxmd.com/read/28732060/formation-of-singlet-oxygen-by-decomposition-of-protein-hydroperoxide-in-photosystem-ii
#1
Vinay Pathak, Ankush Prasad, Pavel Pospíšil
Singlet oxygen (1O2) is formed by triplet-triplet energy transfer from triplet chlorophyll to O2 via Type II photosensitization reaction in photosystem II (PSII). Formation of triplet chlorophyll is associated with the change in spin state of the excited electron and recombination of triplet radical pair in the PSII antenna complex and reaction center, respectively. Here, we have provided evidence for the formation of 1O2 by decomposition of protein hydroperoxide in PSII membranes deprived of Mn4O5Ca complex...
2017: PloS One
https://www.readbyqxmd.com/read/28732011/proteomics-analysis-reveals-a-dynamic-diurnal-pattern-of-photosynthesis-related-pathways-in-maize-leaves
#2
Dan Feng, Yanwei Wang, Tiegang Lu, Zhiguo Zhang, Xiao Han
Plant leaves exhibit differentiated patterns of photosynthesis rates under diurnal light regulation. Maize leaves show a single-peak pattern without photoinhibition at midday when the light intensity is maximized. This mechanism contributes to highly efficient photosynthesis in maize leaves. To understand the molecular basis of this process, an isobaric tag for relative and absolute quantitation (iTRAQ)-based proteomics analysis was performed to reveal the dynamic pattern of proteins related to photosynthetic reactions...
2017: PloS One
https://www.readbyqxmd.com/read/28731687/intramolecular-c-h-and-c-f-bond-oxygenation-by-site-differentiated-tetranuclear-manganese-models-of-the-oec
#3
Kurtis M Carsch, Graham de Ruiter, Theodor Agapie
The dangler manganese center in the oxygen-evolving complex (OEC) of photosystem II plays an important role in the oxidation of water to dioxygen. Inspired by the structure of the OEC, we synthesized a series of site-differentiated tetra-manganese clusters [LMn3(PhPz)3OMn][OTf]x (2: x = 2; 3: x = 1) that features an apical manganese ion-distinct from the others-that is appended to a trinuclear manganese core through an μ4-oxygen atom bridge. This cluster design was targeted to facilitate studies of high-valent Mn-oxo formation, which is a proposed step in the mechanism for water oxidation by the OEC...
July 21, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28729902/high-tolerance-to-high-light-conditions-for-the-protected-species-ariocarpus-kotschoubeyanus-cactaceae
#4
Erika Arroyo-Pérez, Joel Flores, Claudia González-Salvatierra, María L Matías-Palafox, Cecilia Jiménez-Sierra
We determined the seasonal ecophysiological performance under perennial plants and under high solar radiation for adult individuals from the 'living rock' cactus Ariocarpus kotschoubeyanus, which occurs equally under nurse plants and in open spaces. We evaluated the effective quantum yield of photosystem II (ΦPSII) and the dissipation of thermal energy [non-photochemical quenching (NPQ)] thorough the year. The maximum apparent electron transport rate (ETRmax) and the saturating photosynthetically active photon flux density for PSII (PFDsat) were also determined from rapid light curves...
2017: Conservation Physiology
https://www.readbyqxmd.com/read/28724227/carbon-and-nitrogen-allocation-strategy-in-posidonia-oceanica-is-altered-by-seawater-acidification
#5
Andrea Scartazza, Stefano Moscatello, Olga Gavrichkova, Maria Cristina Buia, Marco Lauteri, Alberto Battistelli, Maurizio Lorenti, Samantha Laird Garrard, Carlo Calfapietra, Enrico Brugnoli
Rising atmospheric CO2 causes ocean acidification that represents one of the major ecological threats for marine biota. We tested the hypothesis that long-term exposure to increased CO2 level and acidification in a natural CO2 vent system alters carbon (C) and nitrogen (N) metabolism in Posidonia oceanica L. (Delile), affecting its resilience, or capability to restore the physiological homeostasis, and the nutritional quality of organic matter available for grazers. Seawater acidification decreased the C to N ratio in P...
July 14, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28723079/exploring-the-role-of-carbonate-in-the-formation-of-an-organomanganese-tetramer
#6
Karthika J Kadassery, Suman Kr Dey, Alan E Friedman, David C Lacy
The formation of metal-oxygen clusters is an important chemical transformation in biology and catalysis. For example, the biosynthesis of the oxygen-evolving complex in the enzyme photosystem II is a complicated stepwise process that assembles a catalytically active cluster. Herein we describe the role that carbonato ligands have in the formation of the known tetrameric complex [Mn(CO)3(μ3-OH)]4 (1). Complex 1 is synthesized in one step via the treatment of Mn2(CO)10 with excess Me3NO·2H2O. Alternatively, when anhydrous Me3NO is used, an OH-free synthetic intermediate (2) with carbonato ligands is produced...
July 19, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28721457/carbon-use-efficiencies-and-allocation-strategies-in-prochlorococcus-marinus-strain-pcc-9511-during-nitrogen-limited-growth
#7
Kristina Felcmanová, Martin Lukeš, Eva Kotabová, Evelyn Lawrenz, Kimberly H Halsey, Ondřej Prášil
We studied cell properties including carbon allocation dynamics in the globally abundant and important cyanobacterium Prochlorococcus marinus strain PCC 9511 grown at three different growth rates in nitrogen-limited continuous cultures. With increasing nitrogen limitation, cellular divinyl chlorophyll a and the functional absorption cross section of Photosystem II decreased, although maximal photosynthetic efficiency of PSII remained unaltered across all N-limited growth rates. Chl-specific gross and net carbon primary production were also invariant with nutrient-limited growth rate, but only 20% of Chl-specific gross carbon primary production was retained in the biomass across all growth rates...
July 18, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28718766/structural-insights-into-the-light-driven-auto-assembly-process-of-the-water-oxidizing-mn4cao5-cluster-in-photosystem-ii
#8
Miao Zhang, Martin Bommer, Ruchira Chatterjee, Rana Hussein, Junko Yano, Holger Dau, Jan Kern, Holger Dobbek, Athina Zouni
In plants, algae and cyanobacteria, Photosystem II (PSII) catalyzes the light-driven splitting of water at a protein-bound Mn4CaO5-cluster, the water-oxidizing complex (WOC). In the photosynthetic organisms, the light-driven formation of the WOC from dissolved metal ions is a key process because it is essential in both initial activation and continuous repair of PSII. Structural information is required for understanding of this chaperone-free metal-cluster assembly. For the first time, we obtained a structure of PSII from Thermosynechococcus elongatus without the Mn4CaO5-cluster...
July 18, 2017: ELife
https://www.readbyqxmd.com/read/28714937/photosynthesis-inhibiting-activity-of-1-2-chlorophenyl-carbamoyl-and-1-2-nitrophenyl-carbamoyl-naphthalen-2-yl-alkylcarbamates
#9
Tomas Gonec, Josef Stranik, Matus Pesko, Jiri Kos, Michal Oravec, Katarina Kralova, Josef Jampilek
Eight 1-[(2-chlorophenyl)carbamoyl]naphthalen-2-yl alkylcarbamates and eight 1-[(2-nitrophenyl)carbamoyl]naphthalen-2-yl alkylcarbamates were tested for their activity related to the inhibition of photosynthetic electron transport (PET) in spinach (Spinacia oleracea L.) chloroplasts. The PET-inhibiting activity of the compounds was relatively low; the corresponding IC50 values ranged from 0.05 to 0.664 mmol/L; and the highest activity within the series of compounds was observed for 1-[(2-chlorophenyl)-carbamoyl]naphthalen-2-yl propylcarbamate...
July 17, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/28711348/impact-of-molecular-flexibility-on-the-site-energy-shift-of-chlorophylls-in-photosystem-ii
#10
Daniele Narzi, Emanuele Coccia, Marco Manzoli, Leonardo Guidoni
Light harvesting from the Sun by antenna complexes surrounding the reaction center of Photosystem II represents the first step of the natural oxygenic photosynthesis performed by plants, algae and cyanobacteria. The excitation energy derived from the sunlight is absorbed by the chlorophylls of the antenna and subsequently conveyed to the reaction center of Photosystem II through resonant energy transfer mechanisms. In the special pair of chlorophylls of the reaction center the charge separation occurs, eventually leading to the oxidation of water molecules into protons, electrons and molecular oxygen...
July 8, 2017: Biophysical Chemistry
https://www.readbyqxmd.com/read/28710809/the-uvb-photoreceptor-uvr8-mediates-accumulation-of-uv-absorbing-pigments-but-not-changes-in-plant-morphology-under-outdoor-conditions
#11
A Coffey, Els Prinsen, M A K Jansen, James Conway
UVB radiation is biologically active; in plants, it can induce a range of molecular, biochemical, morphological and developmental responses. Although much progress has been made in elucidating UVB perception and signalling pathways under controlled laboratory conditions, understanding of the adaptive, ecological role of UVB responses is still very limited. In this study, we looked at the functional role of UVR8 under outdoor light conditions, by studying growth, photosynthetic competence and accumulation of UV absorbing pigments in a mutant lacking functional UVR8 protein...
July 14, 2017: Plant, Cell & Environment
https://www.readbyqxmd.com/read/28710587/characterization-of-the-sulfur-formation-suf-genes-in-synechocystis-sp-pcc-6803-under-photoautotrophic-and-heterotrophic-growth-conditions
#12
Sha-Sha Zang, Hai-Bo Jiang, Wei-Yu Song, Min Chen, Bao-Sheng Qiu
The sulfur-formation ( suf ) genes play important roles in both photosynthesis and respiration of cyanobacteria, but the organism prioritizes Fe-S clusters for respiration at the expense of photosynthesis. Iron-sulfur (Fe-S) clusters are important to all living organisms, but their assembly mechanism is poorly understood in photosynthetic organisms. Unlike non-photosynthetic bacteria that rely on the iron-sulfur cluster system, Synechocystis sp. PCC 6803 uses the Sulfur-Formation (SUF) system as its major Fe-S cluster assembly pathway...
July 14, 2017: Planta
https://www.readbyqxmd.com/read/28709027/singlet-oxygen-triggers-chloroplast-rupture-and-cell-death-in-the-zeaxanthin-epoxidase-defective-mutant-aba1-of-arabidopsis-thaliana-under-high-light-stress
#13
Álvaro Sánchez-Corrionero, Inmaculada Sánchez-Vicente, Sergio González-Pérez, Ascensión Corrales, Anja Krieger-Liszkay, Óscar Lorenzo, Juan B Arellano
The two Arabidopsis thaliana mutants, aba1 and max4, were previously identified as sharing a number of co-regulated genes with both the flu mutant and Arabidopsis cell suspension cultures exposed to high light (HL). On this basis, we investigated whether aba1 and max4 were generating high amounts of singlet oxygen ((1)O2) and activating (1)O2-mediated cell death. Thylakoids of aba1 produced twice as much (1)O2 as thylakoids of max4 and wild type (WT) plants when illuminated with strong red light. (1)O2 was measured using the spin probe 2,2,6,6-tetramethyl-4-piperidone hydrochloride...
July 4, 2017: Journal of Plant Physiology
https://www.readbyqxmd.com/read/28707658/-phototrophic-microorganisms-in-the-symbiotic-communities-of-baikal-sponges-diversity-of-psba-gene-encoding-d1-protein-of-photosystem-ii-sequences
#14
O V Kaluzhnaya, V B Itskovich
The psbA gene, which encodes a major photosystem II protein (protein II or D1), is a marker for the presence of phototrophic organisms in water communities. We have pioneered the use of this marker for studying the diversity of phototrophic microflora of freshwater invertebrates. The object of the study is the microbial associations accompanying the endemic Baikal sponge Baikalospongia intermedia and the surrounding aquatic microbial community. Analysis of the psbA gene sequences in the examined microbiomes demonstrates the presence of various phototrophic groups, such as Cyanobacteria, Chlorophyta, Heterokonta, Haptophyta, and Ochrophyta algae, as well as cyanophages...
May 2017: Molekuliarnaia Biologiia
https://www.readbyqxmd.com/read/28706530/ftsh2-dependent-proteolysis-of-executer1-is-essential-in-mediating-singlet-oxygen-triggered-retrograde-signaling-in-arabidopsis-thaliana
#15
Vivek Dogra, Jianli Duan, Keun Pyo Lee, Shanshan Lv, Renyi Liu, Chanhong Kim
Photosystem II reaction center (PSII RC) and light-harvesting complex inevitably generate highly reactive singlet oxygen ((1)O2) that can impose photo-oxidative damage, especially when the rate of generation exceeds the rate of detoxification. Besides being toxic, (1)O2 has also been ascribed to trigger retrograde signaling, which leads to nuclear gene expression changes. Two distinctive molecular components appear to regulate (1)O2 signaling: a volatile signaling molecule β-cyclocitral (β-CC) generated upon oxidation of β-carotene by (1)O2 in PSII RC assembled in grana core, and a thylakoid membrane-bound FtsH2 metalloprotease that promotes (1)O2-triggered signaling through the proteolysis of EXECUTER1 (EX1) proteins associated with PSII in grana margin...
2017: Frontiers in Plant Science
https://www.readbyqxmd.com/read/28702790/heavy-metal-induced-oxidative-stress-on-seed-germination-and-seedling-development-a-critical-review
#16
Mihiri Seneviratne, Nishanta Rajakaruna, Muhammad Rizwan, H M S P Madawala, Yong Sik Ok, Meththika Vithanage
Heavy metal contamination in soils can influence plants and animals, often leading to toxicosis. Heavy metals can impact various biochemical processes in plants, including enzyme and antioxidant production, protein mobilization and photosynthesis. Hydrolyzing enzymes play a major role in seed germination. Enzymes such as acid phosphatases, proteases and α-amylases are known to facilitate both seed germination and seedling growth via mobilizing nutrients in the endosperm. In the presence of heavy metals, starch is immobilized and nutrient sources become limited...
July 12, 2017: Environmental Geochemistry and Health
https://www.readbyqxmd.com/read/28702044/leaf-spectral-reflectance-shows-thalassia-testudinum-seedlings-more-sensitive-to-hypersalinity-than-hyposalinity
#17
Michael J Durako, Jacqueline F Howarth
Thalassia testudinum (turtle grass) is the dominant and climax-successional seagrass species in the subtropical/tropical Atlantic and Caribbean region. Two die-offs of T. testudinum in Florida Bay, United States have raised concerns regarding the resilience of this species to environmental disturbances. Seedlings are important in recovery of T. testudinum, following disturbance events. Leaf spectral reflectance [R(λ)] was measured in T. testudinum seedlings exposed for 2 weeks to three salinities (20, 35, and 50) and two light levels (full sun and 50-70% light reduction) in experimental mesocosms...
2017: Frontiers in Plant Science
https://www.readbyqxmd.com/read/28699261/npq-t-a-chlorophyll-fluorescence-parameter-for-rapid-estimation-and-imaging-of-non-photochemical-quenching-of-excitons-in-photosystem-ii-associated-antenna-complexes
#18
Stefanie Tietz, Christopher C Hall, Jeffrey A Cruz, David M Kramer
In photosynthesis, light energy is absorbed by light-harvesting complexes and used to drive photochemistry. However, a fraction of absorbed light is lost to non-photochemical quenching (NPQ) that reflects several important photosynthetic processes to dissipate excess energy. Currently, estimates of NPQ and its individual components (qE , qI , qZ and qT ) are measured from pulse-amplitude-modulation (PAM) measurements of chlorophyll fluorescence yield and require measurements of the maximal yield of fluorescence in fully dark-adapted material (Fm ), when NPQ is assumed to be negligible...
August 2017: Plant, Cell & Environment
https://www.readbyqxmd.com/read/28698879/complete-chloroplast-genome-sequence-of-coptis-chinensis-franch-and-its-evolutionary-history
#19
Yang He, Hongtao Xiao, Cao Deng, Gang Fan, Shishang Qin, Cheng Peng
The Coptis chinensis Franch. is an important medicinal plant from the Ranunculales. We used next generation sequencing technology to determine the complete chloroplast genome of C. chinensis. This genome is 155,484 bp long with 38.17% GC content. Two 26,758 bp long inverted repeats separated the genome into a typical quadripartite structure. The C. chinensis chloroplast genome consists of 128 gene loci, including eight rRNA gene loci, 28 tRNA gene loci, and 92 protein-coding gene loci. Most of the SSRs in C...
2017: BioMed Research International
https://www.readbyqxmd.com/read/28690669/establishment-of-integrated-protocols-for-automated-high-throughput-kinetic-chlorophyll-fluorescence-analyses
#20
Henning Tschiersch, Astrid Junker, Rhonda C Meyer, Thomas Altmann
BACKGROUND: Automated plant phenotyping has been established as a powerful new tool in studying plant growth, development and response to various types of biotic or abiotic stressors. Respective facilities mainly apply non-invasive imaging based methods, which enable the continuous quantification of the dynamics of plant growth and physiology during developmental progression. However, especially for plants of larger size, integrative, automated and high throughput measurements of complex physiological parameters such as photosystem II efficiency determined through kinetic chlorophyll fluorescence analysis remain a challenge...
2017: Plant Methods
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