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https://www.readbyqxmd.com/read/28334627/a-novel-versatile-microbiosensor-for-local-hydrogen-detection-by-means-of-scanning-photoelectrochemical-microscopy
#1
Fangyuan Zhao, Felipe Conzuelo, Volker Hartmann, Huaiguang Li, Stefanie Stapf, Marc M Nowaczyk, Matthias Rögner, Nicolas Plumeré, Wolfgang Lubitz, Wolfgang Schuhmann
The development of a versatile microbiosensor for hydrogen detection is reported. Carbon-based microelectrodes were modified with a [NiFe]-hydrogenase embedded in a viologen-modified redox hydrogel for the fabrication of a sensitive hydrogen biosensor By integrating the microbiosensor in a scanning photoelectrochemical microscope, it was capable of serving simultaneously as local light source to initiate photo(bio)electrochemical reactions while acting as sensitive biosensor for the detection of hydrogen. A hydrogen evolution biocatalyst based on photosystem 1-platinum nanoparticle biocomplexes embedded into a specifically designed redox polymer was used as a model for proving the capability of the developed hydrogen biosensor for the detection of hydrogen upon localized illumination...
March 18, 2017: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/28328165/variation-in-growth-rate-carbon-assimilation-and-photosynthetic-efficiency-in-response-to-nitrogen-source-and-concentration-in-phytoplankton-isolated-from-upper-san-francisco-bay
#2
Gry Mine Berg, Sara Driscoll, Kendra Hayashi, Melissa Ross, Raphael Kudela
Six species of phytoplankton recently isolated from upper San Francisco Bay were tested for their sensitivity to growth inhibition by ammonium (NH4(+) ), and for differences in growth rates according to inorganic nitrogen (N) growth source. The quantum yield of photosystem II (Fv /Fm ) was a sensitive indicator of NH4(+) toxicity, manifested by a suppression of Fv /Fm in a dose-dependent manner. Two chlorophytes were the least sensitive to NH4(+) inhibition, at concentrations of >3000 μmoles NH4(+) · L(-1) , followed by two estuarine diatoms which were sensitive at concentrations >1000 μmoles NH4(+) · L(-1) , followed lastly by two freshwater diatoms that were sensitive at concentrations between 200-500 μmoles NH4(+) · L(-1) ...
March 22, 2017: Journal of Phycology
https://www.readbyqxmd.com/read/28326554/chlamydomonas-reinhardtii-responding-to-high-light-a-role-for-2-propenal-acrolein
#3
Thomas Roach, Theresa Baur, Wolfgang Stöggl, Anja Krieger-Liszkay
High light causes photosystem II to generate singlet oxygen ((1) O2 ), a reactive oxygen species (ROS) that can react with membrane lipids, releasing reactive electrophile species (RES), such as acrolein. To investigate how RES may contribute to light stress responses, Chlamydomonas reinhardtii was high light-treated in photoautotrophic and mixotrophic conditions and also in an oxygen-enriched atmosphere to elevate ROS production. The responses were compared to exogenous acrolein. Non-photochemical quenching (NPQ) was higher in photoautotrophic cells, as a consequence of a more de-epoxidized state of the xanthophyll cycle pool and more LHCSR3 protein, showing that photosynthesis was under more pressure than in mixotrophic cells...
March 21, 2017: Physiologia Plantarum
https://www.readbyqxmd.com/read/28325832/physiological-effects-of-temperature-do-not-explain-prevalence-of-females-in-populations-of-gynodioecious-lobelia-siphilitica-growing-in-warmer-climates
#4
Maia F Bailey, Andrea L Case, Christina M Caruso
PREMISE OF THE STUDY: Gynodioecy is a sexual polymorphism whereby female and hermaphroditic plants co-occur within populations. In many gynodioecious species, stressful abiotic environments are associated with higher frequencies of females. This association suggests that abiotic stress affects the relative fitness of females and hermaphrodites and, thus, the maintenance of gynodioecy. METHODS: To test whether abiotic stress affects the fitness of females and hermaphrodites, we grew open-pollinated Lobelia siphilitica families in temperature regimes characteristic of the southern portion of the species' range (where females are common) and the northern portion of the range (where females are rare)...
March 21, 2017: American Journal of Botany
https://www.readbyqxmd.com/read/28325764/the-vitamin-b12-dependent-photoreceptor-aerr-relieves-photosystem-gene-repression-by-extending-the-interaction-of-crtj-with-photosystem-promoters
#5
Mingxu Fang, Carl E Bauer
Purple nonsulfur bacteria adapt their physiology to a wide variety of environmental conditions often through the control of transcription. One of the main transcription factors involved in controlling expression of the Rhodobacter capsulatus photosystem is CrtJ, which functions as an aerobic repressor of photosystem genes. Recently, we reported that a vitamin B12 binding antirepressor of CrtJ called AerR is required for anaerobic expression of the photosystem. However, the mechanism whereby AerR regulates CrtJ activity is unclear...
March 21, 2017: MBio
https://www.readbyqxmd.com/read/28324684/tea-is-a-key-virulence-factor-for-alternaria-alternata-fr-keissler-infection-of-its-host
#6
Ye Kang, Hongwei Feng, Jingxu Zhang, Shiguo Chen, Bernal E Valverde, Sheng Qiang
A toxin-deficient mutant strain, HP001 mutant of Alternaria alternata, whose mycelium is unable to infect its host, produces little tenuazonic acid (TeA) toxin. How TeA plays a role in initiating host infection by A. alternata remains unclear. In this research we use Imaging-PAM based on chlorophyll fluorescence parameters and transmission electron microscopy to explore the role of TeA toxin during the infection process of A. alternata. Photosystem II damage began even before wild type mycelium infected the leaves of its host, croftonweed (Ageratina adenophora)...
March 4, 2017: Plant Physiology and Biochemistry: PPB
https://www.readbyqxmd.com/read/28323554/selective-nitration-of-psbo1-inhibits-oxygen-evolution-from-isolated-arabidopsis-thylakoid-membranes
#7
Misa Takahashi, Jun Shigeto, Atsushi Sakamoto, Hiromichi Morikawa
Treatment of isolated Arabidopsis thaliana thylakoid membranes with nitrogen dioxide (NO2) induces selective nitration of the tyrosine residue at the ninth amino acid ((9)Tyr) of PsbO1. This selective nitration is triggered by light and is inhibited by photosynthetic electron transport inhibitors. Therefore, we postulated that, similar to (161)Tyr of D1 (Yz), (9)Tyr of PsbO1 is redox active and is selectively oxidized by photosynthetic electron transport in response to illumination to a tyrosyl radical that is highly susceptible to nitration...
March 21, 2017: Plant Signaling & Behavior
https://www.readbyqxmd.com/read/28320865/9-cis-neoxanthin-in-lhcii-regulates-the-binding-of-violaxanthin-and-xanthophyll-cycle
#8
Ke Wang, Wenfeng Tu, Cheng Liu, Yan Rao, Zhimin Gao, Chunhong Yang
The light harvesting chlorophyll (Chl) a/b complex of photosystem II (LHCII) is able to switch to multiple functions under different light conditions, i.e. harvesting solar energy for photosynthesis and dissipating excess excitation energy for photoprotection. The role of the different carotenoids (Cars) bound to LHCII in regulating the structure and function of the complex is a long-lasting question in photosynthesis research. 9-cis-neoxanthin (Nx) is one of the important Cars, which can only be found in the light harvesting Chla/b complexes of photosystem II...
March 20, 2017: Plant Physiology
https://www.readbyqxmd.com/read/28320288/analysis-of-photoprotection-and-apparent-non-photochemical-quenching-of-chlorophyll-fluorescence-in-tradescantia-leaves-based-on-the-rate-of-irradiance-induced-changes-in-optical-transparence
#9
V V Ptushenko, O S Ptushenko, O P Samoilova, A E Solovchenko
The kinetics of irradiation-induced changes in leaf optical transparence (ΔT) and non-photochemical quenching (NPQ) of chlorophyll fluorescence in Tradescantia fluminensis and T. sillamontana leaves adapted to different irradiance in nature was analyzed. Characteristic times of a photoinduced increase and a dark decline of ΔT in these species were 12 and 20 min, respectively. The ΔT was not confirmed to be the main contributor to the observed middle phase of NPQ relaxation kinetics (τ = 10-28 min). Comparison of rate of photoinduced increase in ΔT and photosystem II quantum yield recovery showed that the former did not affect the tolerance of the photosynthetic apparatus (PSA) to irradiances up to 150 µmol PAR·m(-2)·s(-1)...
January 2017: Biochemistry. Biokhimii︠a︡
https://www.readbyqxmd.com/read/28319223/kinetics-and-heterogeneity-of-energy-transfer-from-light-harvesting-complex-ii-to-photosystem-i-in-the-supercomplex-isolated-from-arabidopsis
#10
Stefano Santabarbara, Tania Tibiletti, William Remelli, Stefano Caffarri
State transitions are a phenomenon that maintains the excitation balance between photosystem II (PSII) and photosystem I (PSI-LHCI) by controlling their relative absorption cross-sections. Under light conditions exciting PSII preferentially, a trimeric LHCII antenna moves from PSII to PSI-LHCI to form the PSI-LHCI-LHCII supercomplex. In this work, the excited state dynamics in the PSI-LHCI and PSI-LHCI-LHCII supercomplexes isolated from Arabidopsis have been investigated by picosecond time-resolved fluorescence spectroscopy...
March 20, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28318016/the-transporter-synpam71-is-located-in-the-plasma-membrane-and-thylakoids-and-mediates-manganese-tolerance-in-synechocystis-pcc6803
#11
Chiara Gandini, Sidsel Birkelund Schmidt, Søren Husted, Anja Schneider, Dario Leister
Manganese (Mn) is an essential constituent of photosystem II (PSII) and therefore indispensable for oxygenic photosynthesis. Very little is known about how Mn is transported, delivered and retained in photosynthetic cells. Recently, the thylakoid-localized transporter PAM71 has been linked to chloroplast Mn homeostasis in Arabidopsis thaliana. Here, we characterize the function of its homolog in Synechocystis (SynPAM71). We used a loss-of-function line (ΔSynPAM71), wild-type (WT) cells exposed to Mn stress and strains expressing a tagged variant of SynPAM71 to characterize the role of SynPAM71 in cyanobacterial Mn homeostasis...
March 20, 2017: New Phytologist
https://www.readbyqxmd.com/read/28317065/interactions-of-arbuscular-mycorrhizal-and-endophytic-fungi-improve-seedling-survival-and-growth-in-post-mining-waste
#12
Katarzyna Wężowicz, Piotr Rozpądek, Katarzyna Turnau
The impact of fungal endophytes and the modulating role of arbuscular mycorrhizal fungi (AMF) on the vitality of Verbascum lychnitis, grown in the laboratory in a substratum from a post-mining waste dump was investigated. We report that inoculation with a single endophyte negatively affected the survival rate and biomass production of most of the plant-endophyte consortia examined. The introduction of arbuscular mycorrhiza fungi into this setup (dual inoculation) had a beneficial effect on both biomass yield and survivability...
March 20, 2017: Mycorrhiza
https://www.readbyqxmd.com/read/28315793/highlighting-the-effects-of-coumarin-on-adult-plants-of-arabidopsis-thaliana-l-heynh-by-an-integrated-omic-approach
#13
Fabrizio Araniti, Monica Scognamiglio, Angela Chambery, Rosita Russo, Assunta Esposito, Brigida D'Abrosca, Antonio Fiorentino, Antonio Lupini, Francesco Sunseri, Maria Rosa Abenavoli
In this study, the effects of the allelochemical coumarin through a metabolomic, proteomic and morpho-physiological approach in Arabidopsis adult plants (25days old) were investigated. Metabolomic analysis evidenced an increment of amino acids and a high accumulation of soluble sugars, after 6days of coumarin treatment. This effect was accompanied by a strong decrease on plant fresh and dry weights, as well as on total protein content. On the contrary, coumarin did not affect leaf number but caused a reduction in leaf area...
March 1, 2017: Journal of Plant Physiology
https://www.readbyqxmd.com/read/28315679/charged-groups-at-binding-interfaces-of-the-psbo-subunit-of-photosystem-ii-a-combined-bioinformatics-and-simulation-study
#14
Coral Del Val, Ana-Nicoleta Bondar
PsbO is an extrinsic subunit of photosystem II engaged in complex binding interactions within photosystem II. At the interface between PsbO, D1 and D2 subunits of photosystem II, a cluster of charged and polar groups of PsbO is part of an extended hydrogen-bond network thought to participate in proton transfer. The precise role of specific amino acid residues at this complex binding interface remains a key open question. Here, we address this question by carrying out extensive bioinformatics analyses and molecular dynamics simulations of PsbO proteins with mutations at the binding interface...
March 15, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28315315/connectivity-among-photosystem-ii-centers-in-phytoplankters-patterns-and-responses
#15
Kui Xu, Jessica L Grant-Burt, Natalie Donaher, Douglas A Campbell
Fast Repetition and Relaxation chlorophyll fluorescence induction is used to estimate the effective absorption cross section of PSII (σPSII), to analyze phytoplankton acclimation and electron transport. The fitting coefficient ρ measures excitation transfer from closed PSII to remaining open PSII upon illumination, which could theoretically generate a progressive increase in σPSII for the remaining open PSII. To investigate how ρ responds to illumination we grew marine phytoplankters with diverse antenna structures (Prochlorococcus, Synechococcus, Ostreococcus and Thalassiosira pseudonana) under limiting or saturating growth light...
March 14, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28315133/remembering-navasard-v-karapetyan-1936-2015
#16
Nadezhda P Yurina, Vladimir O Popov, Alexander A Krasnovsky, Govindjee
Navasard Vaganovich Karapetyan (September 6, 1936-March 6, 2015) began his scientific career at the Bach Institute of Biochemistry of the Russian Academy of Sciences, Moscow, and was associated with this institute for over 56 years. He worked in the area of biochemistry and biophysics of photosynthesis and was especially known for his studies on chlorophyll a fluorescence in higher plants and cyanobacteria, molecular organization of Photosystem I, photoprotective energy dissipation, and dynamics of energy migration in the two photosystems...
March 17, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28304077/alternative-electron-transport-mediated-by-flavodiiron-proteins-is-operational-in-organisms-from-cyanobacteria-up-to-gymnosperms
#17
Petr Ilík, Andrej Pavlovič, Roman Kouřil, Alessandro Alboresi, Tomas Morosinotto, Yagut Allahverdiyeva, Eva-Mari Aro, Hiroshi Yamamoto, Toshiharu Shikanai
Photo-reduction of O2 to water mediated by flavodiiron proteins (FDPs) represents a safety valve for the photosynthetic electron transport chain in fluctuating light. So far, the FDP-mediated O2 photo-reduction has been evidenced only in cyanobacteria and the moss Physcomitrella; however, a recent phylogenetic analysis of transcriptomes of photosynthetic organisms has also revealed the presence of FDP genes in several nonflowering plant groups. What remains to be clarified is whether the FDP-dependent O2 photo-reduction is actually operational in these organisms...
March 17, 2017: New Phytologist
https://www.readbyqxmd.com/read/28303390/the-hydroperoxide-lyase-branch-of-the-oxylipin-pathway-protects-against-photoinhibition-of-photosynthesis
#18
Tatyana Savchenko, Denis Yanykin, Andrew Khorobrykh, Vasily Terentyev, Vyacheslav Klimov, Katayoon Dehesh
This study describes a new role for hydroperoxide lyase branch of oxylipin biosynthesis pathway in protecting photosynthetic apparatus under high light conditions. Lipid-derived signaling molecules, oxylipins, produced by a multi-branch pathway are central in regulation of a wide range of functions. The two most known branches, allene oxide synthase (AOS) and 13-hydroperoxide lyase (HPL) pathways, are best recognized as producers of defense compounds against biotic challenges. In the present work, we examine the role of these two oxylipin branches in plant tolerance to the abiotic stress, namely excessive light...
March 16, 2017: Planta
https://www.readbyqxmd.com/read/28302724/genetically-introduced-hydrogen-bond-interactions-reveal-an-asymmetric-charge-distribution-on-the-radical-cation-of-the-special-pair-chlorophyll-p680
#19
Ryo Nagao, Motoki Yamaguchi, Shin Nakamura, Hanayo Ueoka-Nakanishi, Takumi Noguchi
The special-pair chlorophyll (Chl) P680 in photosystem II has an extremely high redox potential (Em) to enable water oxidation in photosynthesis. Significant positive charge localization on one of the Chl constituents, PD1 or PD2, in P680(+) has been proposed to contribute to this high Em To identify the Chl molecule on which the charge is mainly localized, we genetically introduced a hydrogen bond to the 13(1)-keto C=O group of PD1 and PD2 by changing the nearby D1-V157 and D2-V156 residues to His, respectively...
March 16, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28300765/hydrogen-production-by-a-chlamydomonas-reinhardtii-strain-with-inducible-expression-of-photosystem-ii
#20
Khorcheska Batyrova, Patrick C Hallenbeck
Chlamydomonas reinhardtii cy6Nac2.49 is a genetically modified algal strain that activates photosynthesis in a cyclical manner, so that photosynthesis is not active constitutively in the presence of oxygen, but is turned on only in response to a metabolic trigger (anaerobiosis). Here, we further investigated hydrogen production by this strain comparing it with the parental wild-type strain under photoheterotrophic conditions in regular tris-acetate-phosphate (TAP) medium with a 10-h:14-h light/dark regime. Unlike the wild-type, whose level of H₂ production remained low during illumination, H₂ production in the mutant strain increased gradually with each subsequent light period, and by the final light period was significantly higher than the wild-type...
March 16, 2017: International Journal of Molecular Sciences
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