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https://www.readbyqxmd.com/read/28645032/physiological-traits-and-antioxidant-metabolism-of-leaves-of-tropical-woody-species-challenged-with-cement-dust
#1
Advanio Inácio Siqueira-Silva, Eduardo Gusmão Pereira, José Pires de Lemos-Filho, Luzia Valentina Modolo, Elder Antonio Sousa Paiva
Tropical woody species occurring in limestone outcrops are frequently exposed to particulate material from cement factories. The effects of 60-day cement dust exposure on physiological traits and enzymatic antioxidant system of young plant leaves of Guazuma ulmifolia Lam., Myracrodruon urundeuva Allemão and Trichilia hirta L. were investigated. Cement dust (2.5 or 5mgcm(-2)) was applied to the leaf surface or soil or both (leaf plus soil) and plants were maintained at greenhouse. Cement dust barely affected the mineral nutrient levels, except for iron whose content was decreased in leaves/leaflets of all species studied...
June 20, 2017: Ecotoxicology and Environmental Safety
https://www.readbyqxmd.com/read/28644828/a-mutant-of-chlamydomonas-without-lhcsr-maintains-high-rates-of-photosynthesis-but-has-reduced-cell-division-rates-in-sinusoidal-light-conditions
#2
Michael Cantrell, Graham Peers
The LHCSR protein belongs to the light harvesting complex family of pigment-binding proteins found in oxygenic photoautotrophs. Previous studies have shown that this complex is required for the rapid induction and relaxation of excess light energy dissipation in a wide range of eukaryotic algae and moss. The ability of cells to rapidly regulate light harvesting between this dissipation state and one favoring photochemistry is believed to be important for reducing oxidative stress and maintaining high photosynthetic efficiency in a rapidly changing light environment...
2017: PloS One
https://www.readbyqxmd.com/read/28643084/influence-of-knockout-of-at4g20990-gene-encoding-%C3%AE-ca4-on-photosystem-ii-light-harvesting-antenna-in-plants-grown-under-different-light-intensities-and-day-lengths
#3
Natalia N Rudenko, Tatyana P Fedorchuk, Daria V Vetoshkina, Elena M Zhurikova, Lyudmila K Ignatova, Boris N Ivanov
Effect of knockout of the At4g20990 gene encoding α-carbonic anhydrase 4 (α-CA4) in Arabidopsis thaliana in plants grown in low light (LL, 80 μmol photons m(-2) s(-1)) or in high light (HL, 400 μmol photons m(-2) s(-1)) under long (LD, 16 h) or short (SD, 8 h) day length was studied. In α-CA4 knockout plants, under all studied conditions, the non-photochemical quenching was lower; the decrease was more pronounced under HL. This pointed to α-CA4 implication in the processes leading to energy dissipation in PSII antenna...
June 22, 2017: Protoplasma
https://www.readbyqxmd.com/read/28642785/potassium-starvation-limits-soybean-growth-more-than-the-photosynthetic-processes-across-co2-levels
#4
Shardendu K Singh, Vangimalla R Reddy
Elevated carbon dioxide (eCO2) often enhances plant photosynthesis, growth, and productivity. However, under nutrient-limited conditions the beneficial effects of high CO2 are often diminished. To evaluate the combined effects of potassium (K) deficiency and eCO2 on soybean photosynthesis, growth, biomass partitioning, and yields, plants were grown under controlled environment conditions with an adequate (control, 5.0 mM) and two deficient (0.50 and 0.02 mM) levels of K under ambient CO2 (aCO2; 400 μmol mol(-1)) and eCO2 (800 μmol mol(-1))...
2017: Frontiers in Plant Science
https://www.readbyqxmd.com/read/28642783/ibor-regulates-photosynthesis-under-heat-stress-by-stabilizing-ibpsbp-in-sweetpotato
#5
Le Kang, Ho S Kim, Young S Kwon, Qingbo Ke, Chang Y Ji, Sung-Chul Park, Haeng-Soon Lee, Xiping Deng, Sang-Soo Kwak
The Orange (Or) protein regulates carotenoid biosynthesis and environmental stress in plants. Previously, we reported that overexpression of the sweetpotato [Ipomoea batatas (L.) Lam] Or gene (IbOr) in transgenic Arabidopsis (referred to as IbOr-OX/At) increased the efficiency of photosystem II (PSII) and chlorophyll content after heat shock. However, little is known about the role of IbOr in PSII-mediated protection against abiotic stress. In this study, comparative proteomics revealed that expression of PsbP (an extrinsic subunit of PSII) is up-regulated in heat-treated IbOr-OX/At plants...
2017: Frontiers in Plant Science
https://www.readbyqxmd.com/read/28638436/in-vivo-label-free-mapping-of-the-effect-of-a-photosystem-ii-inhibiting-herbicide-in-plants-using-chlorophyll-fluorescence-lifetime
#6
Elizabeth Noble, Sunil Kumar, Frederik G Görlitz, Chris Stain, Chris Dunsby, Paul M W French
BACKGROUND: In order to better understand and improve the mode of action of agrochemicals, it is useful to be able to visualize their uptake and distribution in vivo, non-invasively and, ideally, in the field. Here we explore the potential of plant autofluorescence (specifically chlorophyll fluorescence) to provide a readout of herbicide action across the scales utilising multiphoton-excited fluorescence lifetime imaging, wide-field single-photon excited fluorescence lifetime imaging and single point fluorescence lifetime measurements via a fibre-optic probe...
2017: Plant Methods
https://www.readbyqxmd.com/read/28636143/tetratricopeptide-repeat-protein-pyg7-is-essential-for-photosystem-i-assembly-by-interacting-with-psac-in-arabidopsis
#7
Huixia Yang, Pin Li, Aihong Zhang, Xiaogang Wen, Lixin Zhang, Congming Lu
Although progress has been made in determining the structure and understanding the function of photosystem I (PSI), the PSI assembly process remains poorly understood. PsaC is an essential subunit of PSI and participates in the transfer of electrons to ferredoxin. However, how PsaC is assembled during accumulation of the PSI complex is unknown. In the present study, we showed that Pyg7 localized to the stromal thylakoid and associated with the PSI complex. We also showed that Pyg7 interacted with PsaC. Furthermore, we found that the PSI assembly process was blocked following formation of the PsaAB heterodimer in the pyg7 mutant...
June 21, 2017: Plant Journal: for Cell and Molecular Biology
https://www.readbyqxmd.com/read/28635275/infrared-determination-of-the-protonation-state-of-a-key-histidine-residue-in-the-photosynthetic-water-oxidizing-center
#8
Shin Nakamura, Takumi Noguchi
Photosynthetic water oxidation is performed at the Mn4CaO5 cluster in photosystem II (PSII). The protonation structures of amino acid residues and water molecules around the Mn4CaO5 cluster are crucial in water oxidation reactions. In this study, we determined the protonation state of a key His residue in water oxidation, D1-H337, which is directly hydrogen bonded with the oxygen atom of the Mn4CaO5 cluster, using polarized attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. Flash-induced polarized ATR-FTIR difference spectra upon the S1→S2 transition of oriented PSII membranes showed broad negative and positive features around 2600 and 2900 cm-1, respectively, with large dichroic ratios, accompanied with several minor peaks attributable to the Fermi resonance of a His NH vibration...
June 21, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28634473/toxic-effects-of-prodigiosin-secreted-by-hahella-sp-ka22-on-harmful-alga-phaeocystis-globosa
#9
Huajun Zhang, Hui Wang, Wei Zheng, Zhiyuan Yao, Yun Peng, Su Zhang, Zhong Hu, Zhen Tao, Tianling Zheng
Application of algicidal compounds secreted by bacteria is a promising and environmentally friendly strategy to control harmful algal blooms (HABs). Years ago prodigiosin was described as an efficient algicidal compound, but the details about the effect of prodigiosin on algal cells are still elusive. Prodigiosin shows high algicidal activity on Phaeocystis globosa, making it a potential algicide in HAB control. When P. globosa were treated with prodigiosin at 5 μg/mL, algae cells showed cytoplasmic hypervacuolization, chloroplast and nucleus rupture, flagella missing, and cell fracture, when observed by scanning electron microscope and transmission electron microscopy...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28633086/beneficial-effects-of-melatonin-in-overcoming-drought-stress-in-wheat-seedlings
#10
Guibin Cui, Xiaoxiao Zhao, Shudong Liu, Fengli Sun, Chao Zhang, Yajun Xi
Melatonin plays an important role in abiotic stress in plant, but its role in wheat drought tolerance is less known. To verify its role, wheat seedlings (Triticum aestivum L. 'Yan 995') at 60% and 40% of field capacity were treated with 500 μM melatonin in this study. Melatonin treatment significantly enhanced the drought tolerance of wheat seedlings, as demonstrated by decreased membrane damage, more intact grana lamella of chloroplast, higher photosynthetic rate, and maximum efficiency of photosystem II, as well as higher cell turgor and water holding capacity in melatonin-treated seedlings...
June 15, 2017: Plant Physiology and Biochemistry: PPB
https://www.readbyqxmd.com/read/28631733/plastid-thylakoid-architecture-optimizes-photosynthesis-in-diatoms
#11
Serena Flori, Pierre-Henri Jouneau, Benjamin Bailleul, Benoit Gallet, Leandro F Estrozi, Christine Moriscot, Olivier Bastien, Simona Eicke, Alexander Schober, Carolina Río Bártulos, Eric Maréchal, Peter G Kroth, Dimitris Petroutsos, Samuel Zeeman, Cécile Breyton, Guy Schoehn, Denis Falconet, Giovanni Finazzi
Photosynthesis is a unique process that allows independent colonization of the land by plants and of the oceans by phytoplankton. Although the photosynthesis process is well understood in plants, we are still unlocking the mechanisms evolved by phytoplankton to achieve extremely efficient photosynthesis. Here, we combine biochemical, structural and in vivo physiological studies to unravel the structure of the plastid in diatoms, prominent marine eukaryotes. Biochemical and immunolocalization analyses reveal segregation of photosynthetic complexes in the loosely stacked thylakoid membranes typical of diatoms...
June 20, 2017: Nature Communications
https://www.readbyqxmd.com/read/28626617/doc-concentrations-across-a-depth-dependent-light-gradient-on-a-caribbean-coral-reef
#12
Benjamin Mueller, Erik H Meesters, Fleur C van Duyl
Photosynthates released by benthic primary producers (BPP), such as reef algae and scleractinian corals, fuel the dissolved organic carbon (DOC) production on tropical coral reefs. DOC concentrations near BPP have repeatedly been observed to be elevated compared to those in the surrounding water column. As the DOC release of BPP increases with increasing light availability, elevated DOC concentrations near them will, in part, also depend on light availability. Consequently, DOC concentrations are likely to be higher on the shallow, well-lit reef terrace than in deeper sections on the fore reef slope...
2017: PeerJ
https://www.readbyqxmd.com/read/28620699/evolution-of-chlamydomonas-reinhardtii-ferredoxins-and-their-interactions-with-fefe-hydrogenases
#13
REVIEW
Anne Sawyer, Martin Winkler
Ferredoxins are soluble iron sulphur proteins which function as electron donors in a number of metabolic pathways in a broad range of organisms. In photosynthetic organisms, PETF, or ferredoxin 1 (FDX1), is the most studied ferredoxin due to its essential role in photosynthesis, where it transfers electrons from photosystem I to ferredoxin-NADP(+) oxidoreductase. However, PETF can also transfer electrons to a large number of other proteins. One important PETF electron acceptor found in green microalgae is the biologically and biotechnologically important [FeFe]-hydrogenase HYDA, which catalyses the production of molecular hydrogen (H2) from protons and electrons...
June 15, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28619535/evolution-and-regulation-of-bigelowiella-natans-light-harvesting-antenna-system
#14
Jonathan A D Neilson, Pattarasiri Rangsrikitphoti, Dion G Durnford
Bigelowiella natans is a mixotrophic flagellate and member of the chlorarachniophytes (Rhizaria), whose plastid is derived from a green algal endosymbiont. With the completion of the B. natans nuclear genome we are able to begin the analysis of the structure, function and evolution of the photosynthetic apparatus. B. natans has undergone substantial changes in photosystem structure during the evolution of the plastid from a green alga. While Photosystem II (PSII) composition is well conserved, Photosystem I (PSI) composition has undergone a dramatic reduction in accessory protein subunits...
May 31, 2017: Journal of Plant Physiology
https://www.readbyqxmd.com/read/28608610/identification-of-stable-znii-oxyl-species-enforced-by-mfi-and-its-reversible-reactivity-with-o%C3%A2-at-rt
#15
Yasushige Kuroda, Akira Oda, Takahiro Ohkubo, Takahi Yumura, Hisayoshi Kobayashi
Although a terminal oxyl species bound to certain metal ions is believed to be the intermediate for various oxidation reactions such as O-O bond generation in the photosystem II (PSII), its identification has been elusive. Herein, we report unambiguous identification of a stable ZnII-oxyl species enforced by an MFI-type-zeolite lattice and its reversible reactivity with O₂ at room temperature: [ZnII-O·]+ + O₂ ⇄ [ZnII-O₃·]+. Such intriguing characteristics were evidenced by in situ spectroscopic studies coupled with quantum chemical calculation, i...
June 13, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28607440/an-arabidopsis-mutant-with-high-operating-efficiency-of-photosystem-ii-and-low-chlorophyll-fluorescence
#16
Niels van Tol, Martijn Rolloos, Dieuwertje Augustijn, A Alia, Huub J de Groot, Paul J J Hooykaas, Bert J van der Zaal
The overall light energy to biomass conversion efficiency of plant photosynthesis is generally regarded as low. Forward genetic screens in Arabidopsis have yielded very few mutants with substantially enhanced photochemistry. Here, we report the isolation of a novel Arabidopsis mutant with a high operating efficiency of Photosystem II (φPSII) and low chlorophyll fluorescence from a library of lines harboring T-DNA constructs encoding artificial transcription factors. This mutant was named Low Chlorophyll Fluorescence 1 (LCF1)...
June 12, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28604725/subunit-and-chlorophyll-organization-of-the-plant-photosystem-ii-supercomplex
#17
Laura S van Bezouwen, Stefano Caffarri, Ravindra S Kale, Roman Kouřil, Andy-Mark W H Thunnissen, Gert T Oostergetel, Egbert J Boekema
Photosystem II (PSII) is a light-driven protein, involved in the primary reactions of photosynthesis. In plant photosynthetic membranes PSII forms large multisubunit supercomplexes, containing a dimeric core and up to four light-harvesting complexes (LHCs), which act as antenna proteins. Here we solved a three-dimensional (3D) structure of the C2S2M2 supercomplex from Arabidopsis thaliana using cryo-transmission electron microscopy (cryo-EM) and single-particle analysis at an overall resolution of 5.3 Å...
June 12, 2017: Nature Plants
https://www.readbyqxmd.com/read/28603539/editorial-assembly-of-the-photosystem-ii-membrane-protein-complex-of-oxygenic-photosynthesis
#18
EDITORIAL
Julian J Eaton-Rye, Roman Sobotka
No abstract text is available yet for this article.
2017: Frontiers in Plant Science
https://www.readbyqxmd.com/read/28599858/keeping-the-spotlight-on-cytochrome-p450
#19
REVIEW
Hadil Shalan, Mallory Kato, Lionel Cheruzel
This review describes the recent advances utilizing photosensitizers and visible light to harness the synthetic potential of P450 enzymes. The structures of the photosensitizers investigated to date are first presented along with their photophysical and redox properties. Functional photosensitizers range from organic and inorganic complexes to nanomaterials as well as the biological photosystem I complex. The focus is then on the three distinct approaches that have emerged for the activation of P450 enzymes...
June 6, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28597651/in-operando-investigation-of-electrically-coupling-of-photosystem-1-and-photosystem-2-by-means-of-bipolar-electrochemistry
#20
Vera Essmann, Fangyuan Zhao, Volker Hartmann, Marc M Nowaczyk, Wolfgang Schuhmann, Felipe Conzuelo
Electrochemical communication between two photobioelectrochemical half-cells based on photosystem 1 and photo-system 2 is investigated in operando. The driving force for the electron transfer reactions is applied in a wireless mode using bipolar electrochemistry with the actual electrode potentials being self-regulated by the redox processes. Four parameters are assessed to understand the overall performance and elucidate the limiting reactions of the photobioe-lectrochemical cell. In addition to the potential differences for oxidation and reduction reactions, the current flowing between the half-cells as well as in situ collection of locally evolved O2 by photosystem 2 using a positioned SECM tip are evaluated...
June 9, 2017: Analytical Chemistry
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