WorldWideScience

Sample records for reaction center chlorophyll

  1. Nuclear Reaction Data Centers

    International Nuclear Information System (INIS)

    McLane, V.; Nordborg, C.; Lemmel, H.D.; Manokhin, V.N.

    1988-01-01

    The cooperating Nuclear Reaction Data Centers are involved in the compilation and exchange of nuclear reaction data for incident neutrons, charged particles and photons. Individual centers may also have services in other areas, e.g., evaluated data, nuclear structure and decay data, reactor physics, nuclear safety; some of this information may also be exchanged between interested centers. 20 refs., 1 tab

  2. Electron transfer reactions involving porphyrins and chlorophyll a

    International Nuclear Information System (INIS)

    Neta, P.; Scherz, A.; Levanon, H.

    1979-01-01

    Electron transfer reactions involving porphyrins (P) and quinones (Q) have been studied by pulse radiolysis. The porphyrins used were tetraphenylporphyrin (H 2 TPP), its tetracarboxy derivative (H 2 TCPP), the sodium and zinc compounds (Na 2 TPP and ZnTPP), and chlorophyll a (Chl a). These compounds were found to be rapidly reduced by electron transfer from (CH 3 ) 2 CO - . Reduction by (CH 3 ) 2 COH was rapid in aqueous solutions but relatively slow in i-PrOH solutions. Transient spectra of the anion radicals were determined and, in the case of H 2 TCPP - ., a pK = 9.7 was derived for its protonation. Electron-transfer reactions from the anion radical of H 2 TCPP to benzoquinone, duroquinone, 9,10-anthraquinone 2-sulfonate, and methylviologen occur in aqueous solutions with rate constants approx. 10 7 -10 9 M -1 s -1 which depend on the pH and the quinone reduction potential. Reactions of Na 2 TPP - ., ZnTPP - ., and Chl a - . with anthraquinone in basic i-PrOH solutions occur with rate constants approx. 10 9 M -1 s -1 . The spectral changes associated with these electron-transfer reactions as observed over a period of approx. 1 ms indicated, in some cases, the formation of an intermediate complex [P...Q - .]. 8 figures, 2 tables

  3. Identification of the 7-Hydroxymethyl Chlorophyll a Reductase of the Chlorophyll Cycle in Arabidopsis[W

    Science.gov (United States)

    Meguro, Miki; Ito, Hisashi; Takabayashi, Atsushi; Tanaka, Ryouichi; Tanaka, Ayumi

    2011-01-01

    The interconversion of chlorophyll a and chlorophyll b, referred to as the chlorophyll cycle, plays a crucial role in the processes of greening, acclimation to light intensity, and senescence. The chlorophyll cycle consists of three reactions: the conversions of chlorophyll a to chlorophyll b by chlorophyllide a oxygenase, chlorophyll b to 7-hydroxymethyl chlorophyll a by chlorophyll b reductase, and 7-hydroxymethyl chlorophyll a to chlorophyll a by 7-hydroxymethyl chlorophyll a reductase. We identified 7-hydroxymethyl chlorophyll a reductase, which is the last remaining unidentified enzyme of the chlorophyll cycle, from Arabidopsis thaliana by genetic and biochemical methods. Recombinant 7-hydroxymethyl chlorophyll a reductase converted 7-hydroxymethyl chlorophyll a to chlorophyll a using ferredoxin. Both sequence and biochemical analyses showed that 7-hydroxymethyl chlorophyll a reductase contains flavin adenine dinucleotide and an iron-sulfur center. In addition, a phylogenetic analysis elucidated the evolution of 7-hydroxymethyl chlorophyll a reductase from divinyl chlorophyllide vinyl reductase. A mutant lacking 7-hydroxymethyl chlorophyll a reductase was found to accumulate 7-hydroxymethyl chlorophyll a and pheophorbide a. Furthermore, this accumulation of pheophorbide a in the mutant was rescued by the inactivation of the chlorophyll b reductase gene. The downregulation of pheophorbide a oxygenase activity is discussed in relation to 7-hydroxymethyl chlorophyll a accumulation. PMID:21934147

  4. Chlorophyll d: the puzzle resolved

    DEFF Research Database (Denmark)

    Larkum, Anthony W D; Kühl, Michael

    2005-01-01

    Chlorophyll a (Chl a) has always been regarded as the sole chlorophyll with a role in photochemical conversion in oxygen-evolving phototrophs, whereas chlorophyll d (Chl d), discovered in small quantities in red algae in 1943, was often regarded as an artefact of isolation. Now, as a result...... of discoveries over the past year, it has become clear that Chl d is the major chlorophyll of a free-living and widely distributed cyanobacterium that lives in light environments depleted in visible light and enhanced in infrared radiation. Moreover, Chl d not only has a light-harvesting role but might also...... replace Chl a in the special pair of chlorophylls in both reactions centers of photosynthesis. Udgivelsesdato: 2005-Aug...

  5. Efficacy of chlorophyll c2 for seasonal allergic rhinitis: single-center double-blind randomized control trial.

    Science.gov (United States)

    Fujiwara, Takashi; Nishida, Naoya; Nota, Jumpei; Kitani, Takashi; Aoishi, Kunihide; Takahashi, Hirotaka; Sugahara, Takuya; Hato, Naohito

    2016-12-01

    Chlorophyll c2 extracted from Sargassum horneri improved allergic symptoms in an animal model of allergic rhinitis. In the present study, we explored the efficacy of chlorophyll c2 in patients with seasonal allergic rhinitis. This was a single-center, randomized, double-blind placebo-controlled trial. Sixty-six patients aged 20-43 years, each with a 2-year history of seasonal allergic rhinitis, were randomly assigned to receive either a single daily dose (0.7 mg) of chlorophyll c2 or placebo for 12 weeks. The use of medications including H1-antihistamines and topical nasal steroids was recorded by rescue medication scores (RMSs) noted after 4, 8, and 12 weeks of treatment. Disease-specific quality of life was measured using the Japan Rhinitis Quality of Life Questionnaire (JRQLQ) both before and after 4, 8, and 12 weeks of treatment. The RMS at 8 weeks was significantly better in the chlorophyll c2 than the placebo group (mean RMS difference = -3.09; 95 % confidence interval = -5.96 to -0.22); the mean RMS at 4 weeks was only slightly better in the chlorophyll c2 group. The JRQLQ scores did not differ significantly between the two groups. Chlorophyll c2 would have a potential to be an alternative treatment for allergic rhinitis.

  6. Photochemical reactions in dehydrated photosynthetic organisms, leaves, chloroplasts and photosystem II particles: reversible reduction of pheophytin and chlorophyll and oxidation of {beta}-carotene

    Energy Technology Data Exchange (ETDEWEB)

    Shuvalov, Vladimir A.; Heber, Ulrich

    2003-11-01

    Photoreactions of dehydrated leaves, isolated broken chloroplasts and PSII membrane fragments of spinach (Spinacia oleracea) were studied at different air humidities and compared with photoreactions of dry fronds of a fern, Polypodium vulgare, and a dry lichen, Parmelia sulcata, which in contrast to spinach are insensitive to photoinactivation in the dry state. Even in very dry air, P700 in the reaction center of photosystem I of dry leaves was oxidized, and the primary quinone acceptor Q{sub A} in the reaction center of photosystem II was photoreduced by low light. These reactions were only very slowly reversed in the dark and saturated under low light intensity. Light-minus-dark difference absorption spectra of the dry leaves, isolated chloroplasts and PSII membrane fragments measured at higher light intensities revealed absorbance changes of {beta}-carotene at 500 nm (light-dependent bleaching) and 980 nm (light-dependent band formation) and bleaching of chlorophyll at 436 and 680 nm with appearance of bands at 450 and 800 nm. Decrease of chlorophyll fluorescence upon strong illumination indicated photoaccumulation of a quencher. All these changes were kinetically related and readily reversible. They are interpreted to show light-induced oxidation of {beta}-carotene (Car) and reduction of chlorophyll-680 (Chl-680) in the reaction center of photosystem II of the dried leaves, chloroplasts and photosystem II particles. The fluorescence quencher was suggested to be Chl-680{sup -} or Car{sup +} in close proximity to P680, the primary electron donor. Appreciable photoaccumulation of reduced pheophytin was only observed in dry leaves after Q{sub A} reduction had been lost during heat treatment of hydrated leaves prior to dehydration. The observations are interpreted to show light-dependent cyclic electron flow within the reaction center of photosystem II in which Chl-680 (or Pheo) is reduced by P680* and Car is oxidized by P680{sup +} with consequent recombination of

  7. Photochemical reactions in dehydrated photosynthetic organisms, leaves, chloroplasts and photosystem II particles: reversible reduction of pheophytin and chlorophyll and oxidation of β-carotene

    International Nuclear Information System (INIS)

    Shuvalov, Vladimir A.; Heber, Ulrich

    2003-01-01

    Photoreactions of dehydrated leaves, isolated broken chloroplasts and PSII membrane fragments of spinach (Spinacia oleracea) were studied at different air humidities and compared with photoreactions of dry fronds of a fern, Polypodium vulgare, and a dry lichen, Parmelia sulcata, which in contrast to spinach are insensitive to photoinactivation in the dry state. Even in very dry air, P700 in the reaction center of photosystem I of dry leaves was oxidized, and the primary quinone acceptor Q A in the reaction center of photosystem II was photoreduced by low light. These reactions were only very slowly reversed in the dark and saturated under low light intensity. Light-minus-dark difference absorption spectra of the dry leaves, isolated chloroplasts and PSII membrane fragments measured at higher light intensities revealed absorbance changes of β-carotene at 500 nm (light-dependent bleaching) and 980 nm (light-dependent band formation) and bleaching of chlorophyll at 436 and 680 nm with appearance of bands at 450 and 800 nm. Decrease of chlorophyll fluorescence upon strong illumination indicated photoaccumulation of a quencher. All these changes were kinetically related and readily reversible. They are interpreted to show light-induced oxidation of β-carotene (Car) and reduction of chlorophyll-680 (Chl-680) in the reaction center of photosystem II of the dried leaves, chloroplasts and photosystem II particles. The fluorescence quencher was suggested to be Chl-680 - or Car + in close proximity to P680, the primary electron donor. Appreciable photoaccumulation of reduced pheophytin was only observed in dry leaves after Q A reduction had been lost during heat treatment of hydrated leaves prior to dehydration. The observations are interpreted to show light-dependent cyclic electron flow within the reaction center of photosystem II in which Chl-680 (or Pheo) is reduced by P680* and Car is oxidized by P680 + with consequent recombination of Car + and Chl-680 - (or Pheo

  8. A multi-pathway model for photosynthetic reaction center

    International Nuclear Information System (INIS)

    Qin, M.; Shen, H. Z.; Yi, X. X.

    2016-01-01

    Charge separation occurs in a pair of tightly coupled chlorophylls at the heart of photosynthetic reaction centers of both plants and bacteria. Recently it has been shown that quantum coherence can, in principle, enhance the efficiency of a solar cell, working like a quantum heat engine. Here, we propose a biological quantum heat engine (BQHE) motivated by Photosystem II reaction center (PSII RC) to describe the charge separation. Our model mainly considers two charge-separation pathways which is more than that typically considered in the published literature. We explore how these cross-couplings increase the current and power of the charge separation and discuss the effects of multiple pathways in terms of current and power. The robustness of the BQHE against the charge recombination in natural PSII RC and dephasing induced by environments is also explored, and extension from two pathways to multiple pathways is made. These results suggest that noise-induced quantum coherence helps to suppress the influence of acceptor-to-donor charge recombination, and besides, nature-mimicking architectures with engineered multiple pathways for charge separations might be better for artificial solar energy devices considering the influence of environments.

  9. Functional type 2 photosynthetic reaction centers found in the rare bacterial phylum Gemmatimonadetes

    OpenAIRE

    Zeng, Yonghui; Feng, Fuying; Medová, Hana; Dean, Jason; Koblížek, Michal

    2014-01-01

    Photosynthesis is one of the most fundamental biological processes on Earth. To date, species capable of performing (bacterio)chlorophyll-based phototrophy have been reported in six bacterial phyla. Here we report a phototrophic bacterium belonging to the rare and understudied phylum Gemmatimonadetes. This strain, isolated from a freshwater lake in the Gobi Desert, contains fully functional photosynthetic reaction centers. Its photosynthesis genes appear to originate from an ancient horizonta...

  10. Photosynthesis and chlorophyll fluorescence reaction to different shade stresses of weak light sensitive maize

    International Nuclear Information System (INIS)

    Wang, J.; Li, F.; Shi, Z.; Huang, H.; Jia, S.

    2017-01-01

    A split-plot experimental study was conducted to evaluate the effect of different shade stresses on photosynthesis and chlorophyll fluorescence of maize leaves.The experiment was designed on the south farm of Special Corn Institute, Shenyang Agricultural University, China.Data was collected from the day maize tasseled (Jul. 21) to the beginning of grouting (Aug.12 ) under 18%, 28%, 38%, 60%, and 75% shade stress to determine indexes such as photosynthesis and chlorophyll fluorescence after 15 days of shade treatment. Pairs of near-isogenic lines (NILs) of Shennong 98A (a barren stalk inbred line) and Shennong 98B (an un-barren stalk inbred line) were used as experimental materials to further reveal photosynthetic mechanisms of weak light sensitive maize when exposed to weak light conditions. Thus, a foundation was established for high density-resistant (shade resistant) corn breeding,while identifying weak light sensitive varieties. After shading treatment, chlorophyll a and total chlorophyll content of both varieties increased, chlorophyll b content first increased, followed by a decrease, while the net photosynthetic rate and stomatal conductance showed a gradually decreasing trend. The changing trends of photochemical quenching coefficient(qp) and effective quantum yield of PSII photochemistry (FPSII)were similar, FPSII and qP increased significantly as shading stress increased from 18% to 38%;however, FPSII and qP declined significantly under 60% and 75% shading stresses. The changing trend of NPQ was opposite to FPSII and qP. A comparison of both inbred lines showed that photosynthesis and chlorophyll fluorescence characteristics of Shennong 98B were superior to Shennong 98A. This study revealed the relationships between weak light sensitive lines and shade intensities by comparing differences in photosynthesis and chlorophyll fluorescence parameters. (author)

  11. Model photo reaction centers via genetic engineering

    Energy Technology Data Exchange (ETDEWEB)

    Zhiyu Wang; DiMagno, T.J.; Popov, M.; Norris, J.R. [Argonne National Lab., IL (United States)]|[Chicago Univ., IL (United States). Dept. of Chemistry; Chikin Chan; Fleming, G. [Chicago Univ., IL (United States). Dept. of Chemistry; Jau Tang; Hanson, D.; Schiffer, M. [Argonne National Lab., IL (United States)

    1992-12-31

    A series of reaction centers of Rhodococcus capsulatus isolated from a set of mutated organisms modified by site-directed mutagenesis at residues M208 and L181 are described. Changes in the amino acid at these sites affect both the energetics of the systems as well as the chemical kinetics for the initial ET event. Two empirical relations among the different mutants for the reduction potential and the ET rate are presented.

  12. Model photo reaction centers via genetic engineering

    Energy Technology Data Exchange (ETDEWEB)

    Zhiyu Wang; DiMagno, T.J.; Popov, M.; Norris, J.R. (Argonne National Lab., IL (United States) Chicago Univ., IL (United States). Dept. of Chemistry); Chikin Chan; Fleming, G. (Chicago Univ., IL (United States). Dept. of Chemistry); Jau Tang; Hanson, D.; Schiffer, M. (Argonne National Lab., IL (United States))

    1992-01-01

    A series of reaction centers of Rhodococcus capsulatus isolated from a set of mutated organisms modified by site-directed mutagenesis at residues M208 and L181 are described. Changes in the amino acid at these sites affect both the energetics of the systems as well as the chemical kinetics for the initial ET event. Two empirical relations among the different mutants for the reduction potential and the ET rate are presented.

  13. Pathways and timescales of primary charge separation in the photosystem II reaction center as revealed by a simultaneous fit of time-resolved fluorescence and transient absorption

    NARCIS (Netherlands)

    Novoderezhkin, V.I.; Andrizhiyevskaya, E.G.; Dekker, J.P.; van Grondelle, R.

    2005-01-01

    We model the dynamics of energy transfer and primary charge separation in isolated photosystem II (PSII) reaction centers. Different exciton models with specific site energies of the six core pigments and two peripheral chlorophylls (Chls) in combination with different charge transfer schemes have

  14. Spectroscopic properties of reaction center pigments in photosystem II core complexes: revision of the multimer model.

    Science.gov (United States)

    Raszewski, Grzegorz; Diner, Bruce A; Schlodder, Eberhard; Renger, Thomas

    2008-07-01

    Absorbance difference spectra associated with the light-induced formation of functional states in photosystem II core complexes from Thermosynechococcus elongatus and Synechocystis sp. PCC 6803 (e.g., P(+)Pheo(-),P(+)Q(A)(-),(3)P) are described quantitatively in the framework of exciton theory. In addition, effects are analyzed of site-directed mutations of D1-His(198), the axial ligand of the special-pair chlorophyll P(D1), and D1-Thr(179), an amino-acid residue nearest to the accessory chlorophyll Chl(D1), on the spectral properties of the reaction center pigments. Using pigment transition energies (site energies) determined previously from independent experiments on D1-D2-cytb559 complexes, good agreement between calculated and experimental spectra is obtained. The only difference in site energies of the reaction center pigments in D1-D2-cytb559 and photosystem II core complexes concerns Chl(D1). Compared to isolated reaction centers, the site energy of Chl(D1) is red-shifted by 4 nm and less inhomogeneously distributed in core complexes. The site energies cause primary electron transfer at cryogenic temperatures to be initiated by an excited state that is strongly localized on Chl(D1) rather than from a delocalized state as assumed in the previously described multimer model. This result is consistent with earlier experimental data on special-pair mutants and with our previous calculations on D1-D2-cytb559 complexes. The calculations show that at 5 K the lowest excited state of the reaction center is lower by approximately 10 nm than the low-energy exciton state of the two special-pair chlorophylls P(D1) and P(D2) which form an excitonic dimer. The experimental temperature dependence of the wild-type difference spectra can only be understood in this model if temperature-dependent site energies are assumed for Chl(D1) and P(D1), reducing the above energy gap from 10 to 6 nm upon increasing the temperature from 5 to 300 K. At physiological temperature, there are

  15. Enriched reaction center preparation from green photosynthetic bacteria. [Chlorobium limicola

    Energy Technology Data Exchange (ETDEWEB)

    Olson, J M; Giddings, Jr, T H; Shaw, E K

    1976-01-01

    Bacteriochlorophyll a reaction-center complex I from Chlorobium limicola f. thiosulfatophilum 6230 (Tassajara) was incubated in 2 M guanidine . HCl and then chromatographed on cross-linked dextran or agarose gel. Two principal components were separated: a larger component with photochemical activity (bacteriochlorophyll a reaction-center complex II) and a smaller component without activity (bacteriochlorophyll a protein). Complex II contains carotenoid, bacteriochlorophyll a, reaction center(s), and cytochromes b and c, but lacks the well characterized bacteriochlorophyll a protein contained in Complex I. Complex II carries out a light-induced reduction of cytochrome b along with an oxidation of cytochrome c.

  16. [Nature of the electron excited state in pigment redox reactions. II. Analysis of the scheme of primary processes in the photooxidation reaction of chlorophylls a and b and pheophytin a ].

    Science.gov (United States)

    Andreeva, N E; Barashkov, B I; Zakharova, G V; Shubin, V V; Chibisov, A K

    1978-01-01

    A scheme of primary reactions in photooxidation of pigments was considered assuming that electron transfer processes can occur via singlet excited as well as triplet states. The results of analysis are compared with the experimental data on relative yield values of chlorophylls a, b, and pheophytin a cation-radicals, as well as with the data on fluorescence quenching. A conclusion has been drawn that photooxidation of pigments proceeds exclusively via the triplet state. The dependence of rate constant quenching values of chlorophyll a triplet state by certain electron acceptors on values of half cell potentials was given.

  17. Mathematical Model of Synthesis Catalyst with Local Reaction Centers

    Directory of Open Access Journals (Sweden)

    I. V. Derevich

    2017-01-01

    Full Text Available The article considers a catalyst granule with a porous ceramic passive substrate and point active centers on which an exothermic synthesis reaction occurs. A rate of the chemical reaction depends on the temperature according to the Arrhenius law. Heat is removed from the pellet surface in products of synthesis due to heat transfer. In our work we first proposed a model for calculating the steady-state temperature of a catalyst pellet with local reaction centers. Calculation of active centers temperature is based on the idea of self-consistent field (mean-field theory. At first, it is considered that powers of the reaction heat release at the centers are known. On the basis of the found analytical solution, which describes temperature distribution inside the granule, the average temperature of the reaction centers is calculated, which then is inserted in the formula for heat release. The resulting system of transcendental algebraic equations is transformed into a system of ordinary differential equations of relaxation type and solved numerically to achieve a steady-state value. As a practical application, the article considers a Fischer-Tropsch synthesis catalyst granule with active cobalt metallic micro-particles. Cobalt micro-particles are the centers of the exothermic reaction of hydrocarbons macromolecular synthesis. Synthesis occurs as a result of absorption of the components of the synthesis gas on metallic cobalt. The temperature distribution inside the granule for a single local center and reaction centers located on the same granule diameter is found. It was found that there is a critical temperature of reactor exceeding of which leads to significant local overheating of the centers - thermal explosion. The temperature distribution with the local reaction centers is qualitatively different from the granule temperature, calculated in the homogeneous approximation. It is shown that, in contrast to the homogeneous approximation, the

  18. The three-dimensional structures of bacterial reaction centers.

    Science.gov (United States)

    Olson, T L; Williams, J C; Allen, J P

    2014-05-01

    This review presents a broad overview of the research that enabled the structure determination of the bacterial reaction centers from Blastochloris viridis and Rhodobacter sphaeroides, with a focus on the contributions from Duysens, Clayton, and Feher. Early experiments performed in the laboratory of Duysens and others demonstrated the utility of spectroscopic techniques and the presence of photosynthetic complexes in both oxygenic and anoxygenic photosynthesis. The laboratories of Clayton and Feher led efforts to isolate and characterize the bacterial reaction centers. The availability of well-characterized preparations of pure and stable reaction centers allowed the crystallization and subsequent determination of the structures using X-ray diffraction. The three-dimensional structures of reaction centers revealed an overall arrangement of two symmetrical branches of cofactors surrounded by transmembrane helices from the L and M subunits, which also are related by the same twofold symmetry axis. The structure has served as a framework to address several issues concerning bacterial photosynthesis, including the directionality of electron transfer, the properties of the reaction center-cytochrome c 2 complex, and the coupling of proton and electron transfer. Together, these research efforts laid the foundation for ongoing efforts to address an outstanding question in oxygenic photosynthesis, namely the molecular mechanism of water oxidation.

  19. Tight-binding model of the photosystem II reaction center: application to two-dimensional electronic spectroscopy

    International Nuclear Information System (INIS)

    Gelzinis, Andrius; Valkunas, Leonas; Abramavicius, Darius; Fuller, Franklin D; Ogilvie, Jennifer P; Mukamel, Shaul

    2013-01-01

    We propose an optimized tight-binding electron–hole model of the photosystem II (PSII) reaction center (RC). Our model incorporates two charge separation pathways and spatial correlations of both static disorder and fast fluctuations of energy levels. It captures the main experimental features observed in time-resolved two-dimensional (2D) optical spectra at 77 K: peak pattern, lineshapes and time traces. Analysis of 2D spectra kinetics reveals that specific regions of the 2D spectra of the PSII RC are sensitive to the charge transfer states. We find that the energy disorder of two peripheral chlorophylls is four times larger than the other RC pigments. (paper)

  20. Tight-binding model of the photosystem II reaction center: application to two-dimensional electronic spectroscopy

    Science.gov (United States)

    Gelzinis, Andrius; Valkunas, Leonas; Fuller, Franklin D.; Ogilvie, Jennifer P.; Mukamel, Shaul; Abramavicius, Darius

    2013-07-01

    We propose an optimized tight-binding electron-hole model of the photosystem II (PSII) reaction center (RC). Our model incorporates two charge separation pathways and spatial correlations of both static disorder and fast fluctuations of energy levels. It captures the main experimental features observed in time-resolved two-dimensional (2D) optical spectra at 77 K: peak pattern, lineshapes and time traces. Analysis of 2D spectra kinetics reveals that specific regions of the 2D spectra of the PSII RC are sensitive to the charge transfer states. We find that the energy disorder of two peripheral chlorophylls is four times larger than the other RC pigments.

  1. Bio-Photoelectrochemical Solar Cells Incorporating Reaction Center and Reaction Center Plus Light Harvesting Complexes

    Science.gov (United States)

    Yaghoubi, Houman

    Harvesting solar energy can potentially be a promising solution to the energy crisis now and in the future. However, material and processing costs continue to be the most important limitations for the commercial devices. A key solution to these problems might lie within the development of bio-hybrid solar cells that seeks to mimic photosynthesis to harvest solar energy and to take advantage of the low material costs, negative carbon footprint, and material abundance. The bio-photoelectrochemical cell technologies exploit biomimetic means of energy conversion by utilizing plant-derived photosystems which can be inexpensive and ultimately the most sustainable alternative. Plants and photosynthetic bacteria harvest light, through special proteins called reaction centers (RCs), with high efficiency and convert it into electrochemical energy. In theory, photosynthetic RCs can be used in a device to harvest solar energy and generate 1.1 V open circuit voltage and ~1 mA cm-2 short circuit photocurrent. Considering the nearly perfect quantum yield of photo-induced charge separation, efficiency of a protein-based solar cell might exceed 20%. In practice, the efficiency of fabricated devices has been limited mainly due to the challenges in the electron transfer between the protein complex and the device electrodes as well as limited light absorption. The overarching goal of this work is to increase the power conversion efficiency in protein-based solar cells by addressing those issues (i.e. electron transfer and light absorption). This work presents several approaches to increase the charge transfer rate between the photosynthetic RC and underlying electrode as well as increasing the light absorption to eventually enhance the external quantum efficiency (EQE) of bio-hybrid solar cells. The first approach is to decrease the electron transfer distance between one of the redox active sites in the RC and the underlying electrode by direct attachment of the of protein complex

  2. Quantum measurement corrections to CIDNP in photosynthetic reaction centers

    International Nuclear Information System (INIS)

    Kominis, Iannis K

    2013-01-01

    Chemically induced dynamic nuclear polarization is a signature of spin order appearing in many photosynthetic reaction centers. Such polarization, significantly enhanced above thermal equilibrium, is known to result from the nuclear spin sorting inherent in the radical pair mechanism underlying long-lived charge-separated states in photosynthetic reaction centers. We will show here that the recently understood fundamental quantum dynamics of radical-ion-pair reactions open up a new and completely unexpected pathway toward obtaining chemically induced dynamic nuclear polarization signals. The fundamental decoherence mechanism inherent in the recombination process of radical pairs is shown to produce nuclear spin polarizations of the order of 10 4 times (or more) higher than the thermal equilibrium value at the Earth's magnetic field relevant to natural photosynthesis. This opens up the possibility of a fundamentally new exploration of the biological significance of high nuclear polarizations in photosynthesis. (paper)

  3. Phytoplankton chlorophyll

    NARCIS (Netherlands)

    van de Poll, W.H.; Kulk, G.; Timmermans, K.R.; Brussaard, C.P.D.; van der Woerd, H.J.; Kehoe, M.J.; Mojica, K.D.A.; Visser, R.J.W.; Rozema, P.D.; Buma, A.G.J.

    2013-01-01

    Relationships between sea surface temperature (SST, > 10 m) and vertical density stratification, nutrient concentrations, and phytoplankton biomass, composition, and chlorophyll a (Chl a) specific absorption were assessed in spring and summer from latitudes 29 to 63 degrees N in the northeast

  4. Conformational regulation of charge recombination reactions in a photosynthetic bacterial reaction center

    DEFF Research Database (Denmark)

    Katona, Gergely; Snijder, Arjan; Gourdon, Pontus Emanuel

    2005-01-01

    In bright light the photosynthetic reaction center (RC) of Rhodobacter sphaeroides stabilizes the P(+)(870).Q(-)(A) charge-separated state and thereby minimizes the potentially harmful effects of light saturation. Using X-ray diffraction we report a conformational change that occurs within the cy...... the cytoplasmic domain of this RC in response to prolonged illumination with bright light. Our observations suggest a novel structural mechanism for the regulation of electron transfer reactions in photosynthesis....

  5. The Type 1 Homodimeric Reaction Center in Heliobacterium modesticaldum

    Energy Technology Data Exchange (ETDEWEB)

    Golbeck, John [Pennsylvania State Univ., University Park, PA (United States)

    2018-01-15

    In this funding period, we (i) found that strong illumination of Heliobacterium modesticaldum cells results in saturation of the electron acceptor pool, leading to reduction of the acceptor side and the creation of a back-reacting state that gives rise to delayed fluorescence; (ii) noted that when the FX cluster is reduced in purified reaction centers, no electron transfer occurs beyond A0, even though a quinone is present; (iii) observed by photochemically induced dynamic nuclear polarization (photo-CIDNP) studies of whole cells of Heliobacterium mobilis that primary charge separation is retained even after conversion of the majority of BChl g to Chl aF. ; and (iv) purified a homogeneous preparation of reaction center cores, which led to promising crystallization trials to obtain a three-dimensional structure.

  6. CHANGES IN CHLOROPHYLL A FLUORENSCENCE AND PIGMENT RATIOS DURING DIFFERENT GROWTH PHASES OF A UNICELLULAR MARINE CHEATOSEROS (BACILLARIOPHYCEAE) IN BATCH CULTURE

    Science.gov (United States)

    Photosystem II reaction centers per cell decreased as the cultures began to decline. The degree of inactivation increased daily as the cell numbers continued to decrease. The concentration of chlorophyll a per cell and the ratio of the major accessory pigments to chlorophyll a (e...

  7. Characterization of chlorophyll binding to LIL3.

    Science.gov (United States)

    Mork-Jansson, Astrid Elisabeth; Eichacker, Lutz Andreas

    2018-01-01

    The light harvesting like protein 3 (LIL 3) from higher plants, has been linked to functions in chlorophyll and tocopherol biosynthesis, photo-protection and chlorophyll transfer. However, the binding of chlorophyll to LIL3 is unclear. We present a reconstitution protocol for chlorophyll binding to LIL3 in DDM micelles. It is shown in the absence of lipids and carotenoids that reconstitution of chlorophyll binding to in vitro expressed LIL3 requires pre-incubation of reaction partners at room temperature. We show chlorophyll a but not chlorophyll b binding to LIL3 at a molar ratio of 1:1. Neither dynamic light scattering nor native PAGE, enabled a discrimination between binding of chlorophyll a and/or b to LIL3.

  8. Pigment organization and their interactions in reaction centers of photosystem II: optical spectroscopy at 6 K of reaction centers with modified pheophytin composition.

    Science.gov (United States)

    Germano, M; Shkuropatov, A Y; Permentier, H; de Wijn, R; Hoff, A J; Shuvalov, V A; van Gorkom, H J

    2001-09-25

    Photosystem II reaction centers (RC) with selectively exchanged pheophytin (Pheo) molecules as described in [Germano, M., Shkuropatov, A. Ya., Permentier, H., Khatypov, R. A., Shuvalov, V. A., Hoff, A. J., and van Gorkom, H. J. (2000) Photosynth. Res. 64, 189-198] were studied by low-temperature absorption, linear and circular dichroism, and triplet-minus-singlet absorption-difference spectroscopy. The ratio of extinction coefficients epsilon(Pheo)/epsilon(Chl) for Q(Y) absorption in the RC is approximately 0.40 at 6 K and approximately 0.45 at room temperature. The presence of 2 beta-carotenes, one parallel and one perpendicular to the membrane plane, is confirmed. Absorption at 670 nm is due to the perpendicular Q(Y) transitions of the two peripheral chlorophylls (Chl) and not to either Pheo. The "core" pigments, two Pheo and four Chl absorb in the 676-685 nm range. Delocalized excited states as predicted by the "multimer model" are seen in the active branch. The inactive Pheo and the nearby Chl, however, mainly contribute localized transitions at 676 and 680 nm, respectively, although large CD changes indicate that exciton interactions are present on both branches. Replacement of the active Pheo prevents triplet formation, causes an LD increase at 676 and 681 nm, a blue-shift of 680 nm absorbance, and a bleach of the 685 nm exciton band. The triplet state is mainly localized on the Chl corresponding to B(A) in purple bacteria. Both Pheo Q(Y) transitions are oriented out of the membrane plane. Their Q(X) transitions are parallel to that plane, so that the Pheos in PSII are structurally similar to their homologues in purple bacteria.

  9. Indicators: Chlorophyll a

    Science.gov (United States)

    Chlorophyll allows plants (including algae) to photosynthesize, i.e., use sunlight to convert simple molecules into organic compounds. Chlorophyll a is the predominant type of chlorophyll found in green plants and algae.

  10. Regulation of Germinal Center Reactions by B and T Cells

    Directory of Open Access Journals (Sweden)

    Yeonseok Chung

    2013-10-01

    Full Text Available Break of B cell tolerance to self-antigens results in the development of autoantibodies and, thus, leads to autoimmunity. How B cell tolerance is maintained during active germinal center (GC reactions is yet to be fully understood. Recent advances revealed several subsets of T cells and B cells that can positively or negatively regulate GC B cell responses in vivo. IL-21-producing CXCR5+ CD4+ T cells comprise a distinct lineage of helper T cells—termed follicular helper T cells (TFH—that can provide help for the development of GC reactions where somatic hypermutation and affinity maturation take place. Although the function of TFH cells is beneficial in generating high affinity antibodies against infectious agents, aberrant activation of TFH cell or B cell to self-antigens results in autoimmunity. At least three subsets of immune cells have been proposed as regulatory cells that can limit such antibody-mediated autoimmunity, including follicular regulatory T cells (TFR, Qa-1 restricted CD8+ regulatory T cells (CD8+TREG, and regulatory B cells (BREG. In this review, we will discuss our current understanding of GC B cell regulation with specific emphasis on the newly identified immune cell subsets involved in this process.

  11. Spectral properties of chlorines and electron transfer with their participation in the photosynthetic reaction center of photosystem II

    Science.gov (United States)

    Shchupak, E. E.; Ivashin, N. V.

    2014-02-01

    Structural factors that provide localization of excited states and determine the properties of primary donor and acceptor of electron in the reaction center of photosystem II (PSII RC) are studied. The results of calculations using stationary and time-dependent density functional theory indicate an important role of protein environments of chlorophylls PA, PB, BA, and BB and pheophytins HA and HB in the area with a radius of no greater than ≤10 Å in the formation of excitonic states of PSII RC. When the neighboring elements are taken into account, the wavelength of long-wavelength Q y transition of chlorophyll molecules is varied by about 10 nm. The effect is less developed for pheophytin molecules (Δλ ≅ 2 nm). The following elements strongly affect energy of the transition: HisA198 and HisD197 amino-acid residues that serve as ligands of magnesium atoms affect PA and PB, respectively; MetA183 affects PA; MetA172 and MetD198 affect BA; water molecules that are located above the planes of the BA and BB macrocycles form H bonds with carbonyl groups; and phytol chains of PA and PB affect BA, BB, HA, and HB. The analysis of excitonic states, mutual positions of molecular orbitals of electron donors and acceptors, and matrix elements of electron transfer reaction shows that (i) charge separation between BA and HA and PB and BA is possible in the active A branch of cofactors of PSII RC and (ii) electron transfer is blocked at the BB - HB fragment in inactive B branch of PSII RC.

  12. Moessbauer spectroscopy on the reaction center of Rhodopseudomonas viridis

    International Nuclear Information System (INIS)

    Frolov, E.; Goldanskii, V.I.; Birk, A.; Parak, F.; Fritzsch, G.; Sinning, I.; Michel, H.

    1992-01-01

    Proteins called 'reaction centers' (RC) can be isolated from many photosynthetic bacteria. They have one non-heme iron in a quinone acceptor region. The RC of Rhodopseudomonas viridis contains an additional tightly bound tetra-heme cytochrome c subunit. The electronic configuration of both cytochrome and the non-heme iron has been studied in the crystallized protein by Moessbauer spectroscopy at different redox potentials, pH-values, and with an addition of o-phenanthroline. At high potentials (E h =+500 mV) all heme irons are in the low spin Fe 3+ -state, and at low potential (E h = 1 50 mV) they are low spin Fe 2+ with the same Moessbauer parameters for all hemes independent of pH. Redox titrations change the relative area of the reduced and oxidized states in agreement with other methods. The non-heme iron shows a high spin Fe 2+ configuration independent of E h and pH with parameters comparable to those of Rhodopseudomonas sphaeroides. Surprisingly, there is strong evidence for another non-heme iron species in part of the molecules with a Fe 2+ low spin configuration. Incubation with o-phenanthroline decreases the relative Fe 2+ hs-area and increases the contribution of Fe 2+ ls-area. Above 210 K the mean square displacement, 2 >, of the RC-crystals increases more than linearly with temperature. This may be correlated with the increase of the electron transfer rate and indicates that intramolecular mobility influences the functional activity of a protein. (orig.)

  13. [Nature of the electron-excited state in redox reactions of pigments. I. Photooxidation of chlorophyll a by n-benzoquine].

    Science.gov (United States)

    Andreeva, N E; Barashkov, B I; Zakharova, G V; Shubin, V V; Chibisov, A K

    1977-01-01

    A method for studying the nature of electronic excited state under photooxidation is proposed. It is shown by an example of the oxidation of chlorophyll a with p-benzoquinone that the formation of cation-radicals of pigments proceeds only through the triplet state. On the basis of experimental data the values of the rate constants of formation of chlorophyll cation-radicals through the singlet-excited state (K2(1)--10(7) M-1 s-1) and triplet state (Kr=10(9) M-1 s-1) of the pigment are evaluated.

  14. Molecular modeling and computational simulation of the photosystem-II reaction center to address isoproturon resistance in Phalaris minor.

    Science.gov (United States)

    Singh, Durg Vijay; Agarwal, Shikha; Kesharwani, Rajesh Kumar; Misra, Krishna

    2012-08-01

    Isoproturon is the only herbicide that can control Phalaris minor, a competitive weed of wheat that developed resistance in 1992. Resistance against isoproturon was reported to be due to a mutation in the psbA gene that encodes the isoproturon-binding D1 protein. Previously in our laboratory, a triazole derivative of isoproturon (TDI) was synthesized and found to be active against both susceptible and resistant biotypes at 0.5 kg/ha but has shown poor specificity. In the present study, both susceptible D1((S)), resistant D1((R)) and D2 proteins of the PS-II reaction center of P. minor have been modeled and simulated, selecting the crystal structure of PS-II from Thermosynechococcus elongatus (2AXT.pdb) as template. Loop regions were refined, and the complete reaction center D1/D2 was simulated with GROMACS in lipid (1-palmitoyl-2-oleoylglycero-3-phosphoglycerol, POPG) environment along with ligands and cofactor. Both S and R models were energy minimized using steepest decent equilibrated with isotropic pressure coupling and temperature coupling using a Berendsen protocol, and subjected to 1,000 ps of MD simulation. As a result of MD simulation, the best model obtained in lipid environment had five chlorophylls, two plastoquinones, two phenophytins and a bicarbonate ion along with cofactor Fe and oxygen evolving center (OEC). The triazole derivative of isoproturon was used as lead molecule for docking. The best worked out conformation of TDI was chosen for receptor-based de novo ligand design. In silico designed molecules were screened and, as a result, only those molecules that show higher docking and binding energies in comparison to isoproturon and its triazole derivative were proposed for synthesis in order to get more potent, non-resistant and more selective TDI analogs.

  15. Chlorophyll: The wonder pigment

    Digital Repository Service at National Institute of Oceanography (India)

    Bhat, S.R.

    Chlorophyll, the green plant pigment, a 'real life force' of living beings, besides synthesizing food, is a great source of vitamins, minerals and other phytochemicals. Adding chlorophyll rich food to our diet fortifies our body against health...

  16. Organization of chlorophyll biosynthesis and insertion of chlorophyll into the chlorophyll-binding proteins in chloroplasts.

    Science.gov (United States)

    Wang, Peng; Grimm, Bernhard

    2015-12-01

    Oxygenic photosynthesis requires chlorophyll (Chl) for the absorption of light energy, and charge separation in the reaction center of photosystem I and II, to feed electrons into the photosynthetic electron transfer chain. Chl is bound to different Chl-binding proteins assembled in the core complexes of the two photosystems and their peripheral light-harvesting antenna complexes. The structure of the photosynthetic protein complexes has been elucidated, but mechanisms of their biogenesis are in most instances unknown. These processes involve not only the assembly of interacting proteins, but also the functional integration of pigments and other cofactors. As a precondition for the association of Chl with the Chl-binding proteins in both photosystems, the synthesis of the apoproteins is synchronized with Chl biosynthesis. This review aims to summarize the present knowledge on the posttranslational organization of Chl biosynthesis and current attempts to envision the proceedings of the successive synthesis and integration of Chl into Chl-binding proteins in the thylakoid membrane. Potential auxiliary factors, contributing to the control and organization of Chl biosynthesis and the association of Chl with the Chl-binding proteins during their integration into photosynthetic complexes, are discussed in this review.

  17. Nuclear Reaction Data File for Astrophysics (NRDF/A) in Hokkaido University Nuclear Reaction Data Center

    International Nuclear Information System (INIS)

    Kato, Kiyoshi; Kimura, Masaaki; Furutachi, Naoya; Makinaga, Ayano; Togashi, Tomoaki; Otuka, Naohiko

    2010-01-01

    The activities of the Japan Nuclear Reaction Data Centre is explained. The main task of the centre is data compilation of Japanese nuclear reaction data in collaboration of the International Network of Nuclear Reaction Data Centres. As one of recent activities, preparation of a new database (NRDF/A) and evaluation of astronuclear reaction data are reported. Collaboration in the nuclear data activities among Asian countries is proposed.

  18. The chlorophyll a fluorescence induction pattern in chloroplasts upon repetitive single turnover excitations: Accumulation and function of QB-nonreducing centers

    NARCIS (Netherlands)

    Vredenberg, W.J.; Kasalicky, V.; Durchan, M.; Prasil, O.

    2006-01-01

    The increase of chlorophyll fluorescence yield in chloroplasts in a 12.5 Hz train of saturating single turnover flashes and the kinetics of fluorescence yield decay after the last flash have been analyzed. The approximate twofold increase in Fm relative to Fo, reached after 30-40 flashes, is

  19. Chalcogenide metal centers for oxygen reduction reaction: Activity and tolerance

    International Nuclear Information System (INIS)

    Feng Yongjun; Gago, Aldo; Timperman, Laure; Alonso-Vante, Nicolas

    2011-01-01

    This mini-review summarizes materials design methods, oxygen reduction kinetics, tolerance to small organic molecules and fuel cell performance of chalcogenide metal catalysts, particularly, ruthenium (Ru x Se y ) and non-precious transition metals (M x X y : M = Co, Fe and Ni; X = Se and S). These non-platinum catalysts are potential alternatives to Pt-based catalysts because of their comparable catalytic activity (Ru x Se y ), low cost, high abundance and, in particular, a high tolerance to small organic molecules. Developing trends of synthesis methods, mechanism of oxygen reduction reaction and applications in direct alcohol fuel cells as well as the substrate effect are highlighted.

  20. Separate photosensitizers mediate degradation of the 32-kDa photosystem II reaction center protein in the visible and UV spectral regions

    International Nuclear Information System (INIS)

    Greenberg, B.M.; Gaba, V.; Canaani, O.; Malkin, S.; Mattoo, A.K.; Edelman, M.

    1989-01-01

    A component of the photosystem II reaction center, the 32-kDa protein, is rapidly turned over in the light. The mechanism of its light-dependent metabolism is largely unknown. We quantified the rate of 32-kDa protein degradation over a broad spectral range (UV, visible, and far red). The quantum yield for degradation was highest in the UVB (280-320 nm) region. Spectral evidence demonstrates two distinctly different photosensitizers for 32-kDa protein degradation. The data implicate the bulk photosynthetic pigments (primarily chlorophyll) in the visible and far red regions, and plastoquinone (in one or more of its redox states) in the UV region. A significant portion of 32-kDa protein degradation in sunlight is attributed to UVB irradiance

  1. 11. IAEA consultants' meeting of the nuclear reaction data centers. Obninsk, 7-11 October 1991

    International Nuclear Information System (INIS)

    Lemmel, H.D.

    1992-03-01

    This report summarizes the 1991 co-ordination meeting in Obninsk, Russia, of the national and regional nuclear reaction data centers, convened by the IAEA at regular intervals. The main topics are: the international exchange of nuclear reaction data by means of the ''EXFOR'' system, and the further development of this system; the ''CINDA'' system as an international index and bibliography to neutron reaction data; the sharing of the workload for speedy and reliable nuclear data compilation; the exchanged and documentation of evaluated data libraries in ENDF format, with the goal of rendering data center services to data users in IAEA Member States by means of computer retrievals, online services and printed materials

  2. Photosynthetic antennas and reaction centers: Current understanding and prospects for improvement

    Energy Technology Data Exchange (ETDEWEB)

    Blankenship, R.E. [Arizona State Univ., Tempe, AZ (United States)

    1996-09-01

    A brief introduction to the principles, structures and kinetic processes that take place in natural photosynthetic reaction center complexes is presented. Energy is first collected by an antenna system, and is transferred to a reaction center complex where primary electron transfer takes place. Secondary reactions lead to oxidation of water and reduction of CO{sub 2} in some classes of organisms. Antenna systems are highly regulated to maximize energy collection efficiency while avoiding photodamage. Some areas that are presently not well understood are listed.

  3. Co-ordination of the nuclear reaction data centers. Report on an IAEA advisory group meeting

    International Nuclear Information System (INIS)

    Schwerer, O.; Lemmel, H.D.

    1996-11-01

    This report summarizes the 1996 co-ordination meeting in Brookhaven, U.S.A., of the national and regional nuclear reaction data center, convened by the IAEA at regular intervals. The main topics are: the international exchange of nuclear reaction data by means of the ''EXFOR'' system, and the further development of this system; the ''CINDA'' system as an international index and bibliography to neutron reaction data; the sharing of the workload for speedy and reliable nuclear data compilation and data center services; the exchange and documentation of evaluated data libraries in ''ENDF'' format; the rapid advances of online electronic information technologies, with the goal of rendering data center services to data users in IAEA Member States by means of computer retrievals, online services and printed materials. The scope of data covers microscopic cross-sections and related parameters of nuclear reactions induced by neutrons, charged-particles and photons. (author). Refs, figs, tabs

  4. Co-ordination of the nuclear reactions data centers. Report on an IAEA advisory group meeting

    International Nuclear Information System (INIS)

    Pronyaev, V.G.; Schwerer, O.

    1998-07-01

    This report summarizes the 1998 co-ordination meeting at the IAEA Headquarters in Vienna of the regional, national and specialized nuclear reaction data centers, concerned by the IAEA at two-year intervals. The main topics are: the international exchange of nuclear reaction data by means of the ''EXFOR'' system, and the further development of this system; the ''CINDA'' system as an international index and bibliography to neutron reaction data; the sharing of the workload for speedy and reliable nuclear data compilation and data center services; the exchange and documentation of evaluated data libraries in ''ENDF'' format; the rapid advances of online electronic information technologies, with goal of rendering data center services to data users in IAEA Member States by means of computer retrievals, online services and printed materials. The scope of data covers microscopic cross-sections and related parameters of nuclear reactions induced by neutrons, charged-particles and photons. (author)

  5. Co-ordination of the nuclear reaction data centers. Report on an IAEA advisory group meeting

    Energy Technology Data Exchange (ETDEWEB)

    Schwerer, O; Lemmel, H D [eds.

    1996-11-01

    This report summarizes the 1996 co-ordination meeting in Brookhaven, U.S.A., of the national and regional nuclear reaction data center, convened by the IAEA at regular intervals. The main topics are: the international exchange of nuclear reaction data by means of the ``EXFOR`` system, and the further development of this system; the ``CINDA`` system as an international index and bibliography to neutron reaction data; the sharing of the workload for speedy and reliable nuclear data compilation and data center services; the exchange and documentation of evaluated data libraries in ``ENDF`` format; the rapid advances of online electronic information technologies, with the goal of rendering data center services to data users in IAEA Member States by means of computer retrievals, online services and printed materials. The scope of data covers microscopic cross-sections and related parameters of nuclear reactions induced by neutrons, charged-particles and photons. (author). Refs, figs, tabs.

  6. Co-ordination of the nuclear reactions data centers. Report on an IAEA advisory group meeting

    Energy Technology Data Exchange (ETDEWEB)

    Pronyaev, V G; Schwerer, O [eds.

    1998-07-01

    This report summarizes the 1998 co-ordination meeting at the IAEA Headquarters in Vienna of the regional, national and specialized nuclear reaction data centers, concerned by the IAEA at two-year intervals. The main topics are: the international exchange of nuclear reaction data by means of the ``EXFOR`` system, and the further development of this system; the ``CINDA`` system as an international index and bibliography to neutron reaction data; the sharing of the workload for speedy and reliable nuclear data compilation and data center services; the exchange and documentation of evaluated data libraries in ``ENDF`` format; the rapid advances of online electronic information technologies, with goal of rendering data center services to data users in IAEA Member States by means of computer retrievals, online services and printed materials. The scope of data covers microscopic cross-sections and related parameters of nuclear reactions induced by neutrons, charged-particles and photons. (author) Refs, figs, tabs

  7. The breakdown of vinyl ethers as a two-center synchronous reaction

    Science.gov (United States)

    Pokidova, T. S.; Shestakov, A. F.

    2009-11-01

    The experimental data on the molecular decomposition of vinyl ethers of various structures to alkanes and the corresponding aldehydes or ketones in the gas phase were analyzed using the method of intersecting parabolas. The enthalpies and kinetic parameters of decomposition were calculated for 17 reactions. The breakdown of ethers is a two-center concerted reaction characterized by a very high classical potential barrier to the thermally neutral reaction (180-190 kJ/mol). The kinetic parameters (activation energies and rate constants) of back reactions of the formation of vinyl ethers in the addition of aldehydes or ketones to alkanes were calculated using the method of intersecting parabolas. The factors that influenced the activation energy of the decomposition and formation of ethers were discussed. Quantum-chemical calculations of several vinyl ether decomposition reactions were performed. Ether formation reactions were compared with the formation of unsaturated alcohols as competitive reactions, which can occur in the interaction of carbonyl compounds with alkenes.

  8. Molecular electronics of a single photosystem I reaction center: Studies with scanning tunneling microscopy and spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Lee, I.; Lee, J.W.; Warmack, R.J.; Allison, D.P.; Greenbaum, E. [Oak Ridge National Lab., TN (United States)

    1995-03-14

    Thylakoids and photosystem I (PSI) reaction centers were imaged by scanning tunneling microscopy. The thylakoids were isolated from spinach chloroplasts, and PSI reaction centers were extracted from thylakoid membranes. Because thylakoids are relatively thick nonconductors, they were sputter-coated with Pd/Au before imaging. PSI photosynthetic centers and chemically platinized PSI were investigated without sputter-coating. They were mounted on flat gold substrates that had been treated with mercaptoacetic acid to help bind the proteins. With tunneling spectroscopy, the PSI centers displayed a semiconductor-like response with a band gap of 1.8 eV. Lightly platinized (platinized for 1 hr) centers displayed diode-like conduction that resulted in dramatic contrast changes between images taken with opposite bias voltages. The electronic properties of this system were stable under long-term storage. 42 refs., 7 figs.

  9. Resident Reactions to Person-Centered Communication by Long-Term Care Staff.

    Science.gov (United States)

    Savundranayagam, Marie Y; Sibalija, Jovana; Scotchmer, Emma

    2016-09-01

    Long-term care staff caregivers who are person centered incorporate the life history, preferences, and feelings of residents with dementia during care interactions. Communication is essential for person-centered care. However, little is known about residents' verbal reactions when staff use person-centered communication. Accordingly, this study investigated the impact of person-centered communication and missed opportunities for such communication by staff on resident reactions. Conversations (N = 46) between staff-resident dyads were audio-recorded during routine care tasks over 12 weeks. Staff utterances were coded for person-centered communication and missed opportunities. Resident utterances were coded for positive reactions, such as cooperation, and negative reactions, such as distress. Linear regression analyses revealed that the more staff used person-centered communication, the more likely that residents reacted positively. Additionally, the more missed opportunities in a conversation, the more likely that the residents reacted negatively. Conversation illustrations elaborate on the quantitative findings and implications for staff training are discussed. © The Author(s) 2016.

  10. Vasovagal reactions in whole blood donors at three REDS-II blood centers in Brazil.

    OpenAIRE

    Gonçalez, TT; Sabino, EC; Schlumpf, KS; Wright, DJ; Leao, S; Sampaio, D; Takecian, PL; Proietti, AB; Murphy, E; Busch, M; Custer, B; NHLBI Retrovirus Epidemiology Donor Study-II REDS-II, International Component,

    2012-01-01

    In Brazil little is known about adverse reactions during donation and the donor characteristics that may be associated with such events. Donors are offered snacks and fluids before donating and are required to consume a light meal after donation. For these reasons the frequency of reactions may be different than those observed in other countries.A cross-sectional study was conducted of eligible whole blood donors at three large blood centers located in Brazil between July 2007 and December 20...

  11. The importance of a hot-sequential mechanism in triplet-state formation by charge recombination in reaction centers of bacterial photosynthesis

    International Nuclear Information System (INIS)

    Saito, K.; Mukai, K.; Sumi, H.

    2006-01-01

    In photosynthesis, pigment-excitation energies in the antenna system produced by light harvesting are transferred among antenna pigments toward the core antenna, where they are captured by the reaction center and initially fixed in the form of a charge separation. Primary charge separation between an oxidized special pair (P + ) and a reduced bacteriopheohytin (H - ) is occasionally intervened by recombination, and a spin-triplet state ( 3 P*) is formed on P in the bacterial reaction center. The 3 P* state is harmful to bio-organisms, inducing the formation of the highly damaging singlet oxygen species. Therefore, understanding the 3 P*-formation mechanism is important. The 3 P* formation is mediated by a state |m> of intermediate charge separation between P and the accessory chlorophyll, which is located between P and H. It will be shown theoretically in the present work that at room temperature, not only the mechanism of superexchange by quantum-mechanical virtual mediation at |m>, but also a hot-sequential mechanism contributes to the mediation. In the latter, although |m> is produced as a real state, the final state 3 P* is quickly formed during thermalization of phonons in the protein matrix in |m>. In the former, the final state is formed more quickly before dephasing-thermalization of phonons in |m>. 3 P* is unistep formed from the charge-separated state in the both mechanisms

  12. Chlorophyll_Master

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set included chlorophyll for each subregion in the study (Georges Bank, Gulf of Maine, Southern New England, Middle Atlantic Bight) . The data came from...

  13. OSU Chlorophyll Bloom Product

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This product was developed for the Oregon coast based on the observed change between running 8-day composite chlorophyll-a (CHL) data obtained by the MODerate...

  14. Vasovagal reactions in whole blood donors at 3 REDS-II blood centers in Brazil

    Science.gov (United States)

    Goncalez, T. T.; Sabino, E. C.; Schlumpf, K.S.; Wright, D.J.; Leao, S.; Sampaio, D.; Takecian, P. L.; Carneiro-Proietti, AB; Murphy, E.; Busch, M.; Custer, B.

    2013-01-01

    Background In Brazil little is known about adverse reactions during donation and the donor characteristics that may be associated with such events. Donors are offered snacks and fluids prior to donating and are required to consume a light meal after donation. For these reasons the frequency of reactions may be different than those observed in other countries. Methods A cross-sectional study was conducted of eligible whole blood donors at three large blood centers located in Brazil between July 2007 and December 2009. Vasovagal reactions (VVRs) along with donor demographic and biometric data were collected. Reactions were defined as any presyncopal or syncopal event during the donation process. Multivariable logistic regression was performed to identify predictors of VVRs. Results Of 724,861 donor presentations, 16,129 (2.2%) VVRs were recorded. Rates varied substantially between the three centers: 53, 290 and 381 per 10,000 donations in Recife, São Paulo and Belo Horizonte, respectively. Although the reaction rates varied, the donor characteristics associated with VVRs were similar [younger age (18–29), replacement donors, first time donors, low estimated blood volume (EBV)]. In multivariable analysis controlling for differences between the donor populations in each city younger age, first-time donor status and lower EBV were the factors most associated with reactions. Conclusion Factors associated with VVRs in other locations are also evident in Brazil. The difference in VVR rates between the three centers might be due to different procedures for identifying and reporting the reactions. Potential interventions to reduce the risk of reactions in Brazil should be considered. PMID:22073941

  15. Biological diversity of photosynthetic reaction centers and the solid-state photo-CIDNP effect

    NARCIS (Netherlands)

    Roy, Esha

    2007-01-01

    Photosynthetic reaction centers (RCs) from plants, heliobacteria and green sulphur bacteria has been investigated with photochemically induced dynamic nuclear polarization (photo-CIDNP) MAS NMR. In photosystem (PS) I of spinach, all signals appear negative which is proposed by a predominance of the

  16. The effects of light-induced reduction of the photosystem II reaction center

    Czech Academy of Sciences Publication Activity Database

    Kutý, Michal

    2009-01-01

    Roč. 8, č. 15 (2009), s. 923-933 ISSN 1610-2940 R&D Projects: GA MŠk(CZ) LC06010 Institutional research plan: CEZ:AV0Z60870520 Keywords : Photosystem II * Reaction center * Pheophytin Subject RIV: CE - Biochemistry Impact factor: 2.336, year: 2009

  17. Functional LH1 antenna complexes influence electron transfer in bacterial photosynthetic reaction centers

    NARCIS (Netherlands)

    Visschers, R.W.; Vulto, S.I.E.; Jones, M.R.; van Grondelle, R.; Kraayenhof, R.

    1999-01-01

    The effect of the light harvesting 1 (LH1) antenna complex on the driving force for light-driven electron transfer in the Rhodobacter sphaeroides reaction center has been examined. Equilibrium redox titrations show that the presence of the LH1 antenna complex influences the free energy change for

  18. Functional LH1 antenna complexes influence electron transfer in bacterial photosynthetic reaction centers.

    NARCIS (Netherlands)

    Visschers, R.W.; Vulto, S.I.E.; Jones, M.R.; van Grondelle, R.; Kraayenhof, R.

    1999-01-01

    The effect of the light harvesting 1 (LH1) antenna complex on the driving force for light-driven electron transfer in the Rhodobacter sphaeroides reaction center has been examined. Equilibrium redox titrations show that the presence of the LH1 antenna complex influences the free energy change for

  19. Reactions of carbon radicals generated by 1,5-transposition of reactive centers

    Directory of Open Access Journals (Sweden)

    ZIVORAD CEKOVIC

    2005-03-01

    Full Text Available Radical intermediates can undergo specific reactions, such as intramolecular rearrangements, i.e., the transpositions of radical centers, which are not known in classical ionic organic reactions. 1,5-Transposition of a radical center to a non-activated carbon atom are of great synthetic importance. It can be successfully applied for the introduction of different functional groups (oxygen, nitrogen, sulfur, halogens onto a carbon atom remote from the present functional group. In addition to functionalization of a remote non-activated carbon atom, the formation of new C-C bonds on the d-carbon atom have also been achieved. 1,5-Transposition of the radical centers takes place from alkoxyl, aminyl and carbon radicals to a remote carbon atom. Relocation of the radical centers preferentially involves 1,5-transfer of a hydrogen atom, although migrations of some other groups are known. The reactions of the carbon radical generated by 1,5-relocation of the radical center are presented and their synthetic applications are reviewed.

  20. Molar extinction coefficients and other properties of an improved reaction center preparation from Rhodopseudomonas viridis

    Energy Technology Data Exchange (ETDEWEB)

    Clayton, R.K.; Clayton, B.J.

    1978-01-01

    Reaction centers have been purified from chromatophores of Rhodopseudomonas viridis by treatment with lauryl dimethyl amine oxide followed by hydroxyapatite chromatography and precipitation with ammonium sulfate. The absorption spectrum at low temperature shows bands at 531 and 543 nm, assigned to two molecules of bacteriopheophytin b. The 600 nm band of bacteriochlorophyll b is resolved at low temperature into components at 601 and 606.5 nm. At room temperature the light-induced difference spectrum shows a negative band centered at 615 nm, where the absorption spectrum shows only a week shoulder adjacent to the 600 nm band. The fluorescence spectrum shows a band at 1000 nm and no fluorescence corresponding to the 830 nm absorption band. Two molecules of cytochrome 558 and three of cytochrome 552 accompany each reaction center. The differential extinction coefficient (reduced minus oxidized) of cytochrome 558 nm was estimated as 20 +- 2 mM/sup -1/.cm/sup -1/ through a coupled reaction with equine cytochrome c. The extinction coefficient of reaction centers at 960 nm was determined to be 123 +- 25 mM/sup -1/.cm/sup -1/ by measuring the light-induced bleaching of P-960 and the coupled oxidation of cytochrome 558. The corresponding extinction coefficient at 830 nm is 300 +- 65 mM/sup -1/.cm/sup -1/. The absorbance ratio ..cap alpha../sub 280nm/..cap alpha../sub 830nm/ in our preparations was 2.1, and there was 190 kg protein per mol of reaction centers. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed three major components of apparent molecular weights 31,000, 37,000, and 41,000.

  1. Chlorophyll b degradation by chlorophyll b reductase under high-light conditions.

    Science.gov (United States)

    Sato, Rei; Ito, Hisashi; Tanaka, Ayumi

    2015-12-01

    The light-harvesting chlorophyll a/b binding protein complex of photosystem II (LHCII) is the main antenna complex of photosystem II (PSII). Plants change their LHCII content depending on the light environment. Under high-light conditions, the content of LHCII should decrease because over-excitation damages the photosystem. Chlorophyll b is indispensable for accumulating LHCII, and chlorophyll b degradation induces LHCII degradation. Chlorophyll b degradation is initiated by chlorophyll b reductase (CBR). In land plants, NON-YELLOW COLORING 1 (NYC1) and NYC1-Like (NOL) are isozymes of CBR. We analyzed these mutants to determine their functions under high-light conditions. During high-light treatment, the chlorophyll a/b ratio was stable in the wild-type (WT) and nol plants, and the LHCII content decreased in WT plants. The chlorophyll a/b ratio decreased in the nyc1 and nyc1/nol plants, and a substantial degree of LHCII was retained in nyc1/nol plants after the high-light treatment. These results demonstrate that NYC1 degrades the chlorophyll b on LHCII under high-light conditions, thus decreasing the LHCII content. After the high-light treatment, the maximum quantum efficiency of the PSII photochemistry was lower in nyc1 and nyc1/nol plants than in WT and nol plants. A larger light-harvesting system would damage PSII in nyc1 and nyc1/nol plants. The fluorescence spectroscopy of the leaves indicated that photosystem I was also damaged by the excess LHCII in nyc1/nol plants. These observations suggest that chlorophyll b degradation by NYC1 is the initial reaction for the optimization of the light-harvesting capacity under high-light conditions.

  2. Geometric phase and quantum interference in photosynthetic reaction center: Regulation of electron transfer

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Yuming, E-mail: ymsun@ytu.edu.cn; Su, Yuehua; Dai, Zhenhong; Wang, WeiTian

    2016-10-20

    Photosynthesis is driven by electron transfer in reaction centers in which the functional unit is composed of several simple molecules C{sub 2}-symmetrically arranged into two branches. In view of quantum mechanism, both branches are possible pathways traversed by the transferred electron. Due to different evolution of spin state along two pathways in transmembrane electric potential (TEP), quantum state of the transferred electron at the bridged site acquires a geometric phase difference dependent on TEP, the most efficient electron transport takes place in a specific range of TEP beyond which electron transfer is dramatically suppressed. What’s more, reaction center acts like elaborately designed quantum device preparing polarized spin dependent on TEP for the transferred electron to regulate the reduction potential at bridged site. In brief, electron transfer generates the TEP, reversely, TEP modulates the efficiency of electron transfer. This may be an important approach to maintaining an appreciable pH environment in photosynthesis.

  3. Nuclear Reaction and Structure Databases of the National Nuclear Data Center

    International Nuclear Information System (INIS)

    Pritychenko, B.; Arcilla, R.; Herman, M. W.; Oblozinsky, P.; Rochman, D.; Sonzogni, A. A.; Tuli, J. K.; Winchell, D. F.

    2006-01-01

    The National Nuclear Data Center (NNDC) collects, evaluates, and disseminates nuclear physics data for basic research and applied nuclear technologies. In 2004, the NNDC migrated all databases into modern relational database software, installed new generation of Linux servers and developed new Java-based Web service. This nuclear database development means much faster, more flexible and more convenient service to all users in the United States. These nuclear reaction and structure database developments as well as related Web services are briefly described

  4. Electrostatic dominoes: long distance propagation of mutational effects in photosynthetic reaction centers of Rhodobacter capsulatus.

    Science.gov (United States)

    Sebban, P; Maróti, P; Schiffer, M; Hanson, D K

    1995-07-04

    Two point mutants from the purple bacterium Rhodobacter capsulatus, both modified in the M protein of the photosynthetic reaction center, have been studied by flash-induced absorbance spectroscopy. These strains carry either the M231Arg --> Leu or M43ASN --> Asp mutations, which are located 9 and 15 A, respectively, from the terminal electron acceptor QB. In the wild-type Rb. sphaeroides structure, M231Arg is involved in a conserved salt bridge with H125Glu and H232Glu and M43Asn is located among several polar residues that form or surround the QB binding site. These substitutions were originally uncovered in phenotypic revertants isolated from the photosynthetically incompetent L212Glu-L213Asp --> Ala-Ala site-specific double mutant. As second-site suppressor mutations, they have been shown to restore the proton transfer function that is interrupted in the L212Ala-L213Ala double mutant. The electrostatic effects that are induced in reaction centers by the M231Arg --> Leu and M43Asn --> Asp substitutions are roughly the same in either the double-mutant or wild-type backgrounds. In a reaction center that is otherwise wild type in sequence, they decrease the free energy gap between the QA- and QB- states by 24 +/- 5 and 45 +/- 5 meV, respectively. The pH dependences of K2, the QA-QB QAQB- equilibrium constant, are altered in reaction centers that carry either of these substitutions, revealing differences in the pKas of titratable groups compared to the wild type.(ABSTRACT TRUNCATED AT 250 WORDS)

  5. A single residue controls electron transfer gating in photosynthetic reaction centers

    Czech Academy of Sciences Publication Activity Database

    Shlyk, O.; Samish, I.; Matěnová, M.; Dulebo, A.; Poláková, H.; Kaftan, David; Scherz, A.

    2017-01-01

    Roč. 7, MAR 16 (2017), s. 1-13, č. článku 44580. ISSN 2045-2322 R&D Projects: GA ČR GA15-00703S; GA MŠk(CZ) LO1416 Institutional support: RVO:61388971 Keywords : BACTERIAL REACTION CENTERS * INDUCED STRUCTURAL-CHANGES * ATOMIC-FORCE MICROSCOPE Subject RIV: EE - Microbiology, Virology OBOR OECD: Microbiology Impact factor: 4.259, year: 2016

  6. Chlorophyll formation and phytochrome

    NARCIS (Netherlands)

    Raven, C.W.

    1973-01-01

    The rôle of phytochrome in the regeneration of protochlorophyll (Pchl) in darkness following short exposures to light, as well as in the accumulation of chlorophyll- a (Chl- a ) in continuous light in previously dark-grown seedlings of pea, bean,

  7. Model of deep centers formation and reactions in electron irradiated InP

    International Nuclear Information System (INIS)

    Sibille, A.; Suski, J.; Gilleron, M.

    1986-01-01

    We present a model of the production of deep centers and their reactions following electron irradiations in InP. We propose that the dominant hole traps in p-InP and electron traps in p + n InP junctions are complexes between shallow acceptors and a common intrinsic entity, the phosphorus interstitial or vacancy. The reactions observed below and above room temperature are then due to a local mobility of this entity, which can be obtained as well by thermal as by electronic stimulation of the reactions. This model implies the long-range migration (at least down to 16 K) of this entity, and explains the strongly different behavior of n-InP compared to p-InP samples

  8. Incidence of transfusion reactions: a multi-center study utilizing systematic active surveillance and expert adjudication

    Science.gov (United States)

    Hendrickson, Jeanne E.; Roubinian, Nareg H.; Chowdhury, Dhuly; Brambilla, Don; Murphy, Edward L.; Wu, Yanyun; Ness, Paul M.; Gehrie, Eric A.; Snyder, Edward L.; Hauser, R. George; Gottschall, Jerome L.; Kleinman, Steve; Kakaiya, Ram; Strauss, Ronald G.

    2017-01-01

    Background Prevalence estimates of serious hazards of transfusion vary widely. We hypothesized that the current reporting infrastructure in the United States fails to capture many transfusion reactions, and undertook a multi-center study utilizing active surveillance, data review, and adjudication to test this hypothesis. Study Design and Methods A retrospective record review was completed for a random sample of 17% of all inpatient transfusion episodes over 6 months at 4 academic tertiary care hospitals, with an episode defined as all blood products released to a patient in 6 hours. Data were recorded by trained clinical research nurses, and serious reactions were adjudicated by a panel of transfusion medicine experts. Results Of 4857 transfusion episodes investigated, 1.1% were associated with a serious reaction. Transfusion associated circulatory overload (TACO) was the most frequent serious reaction noted, being identified in 1% of transfusion episodes. Despite clinical notes describing a potential transfusion association in 59% of these cases, only 5.1% were reported to the transfusion service. Suspected transfusion related acute lung injury (TRALI/possible TRALI), anaphylactic, and hypotensive reactions were noted in 0.08%, 0.02%, and 0.02% of transfusion episodes. Minor reactions, including febrile non-hemolytic and allergic, were noted in 0.62% and 0.29% of transfusion episodes, with 30–50% reported to the transfusion service. Conclusion Underreporting of cardiopulmonary transfusion reactions is striking among academic, tertiary care hospitals. Complete and accurate reporting is essential to identify, define, establish pathogenesis, and mitigate/treat transfusion reactions. A better understanding of the failure to report may improve the accuracy of passive reporting systems. PMID:27460200

  9. Pulse amplitude modulated chlorophyll fluorometer

    Science.gov (United States)

    Greenbaum, Elias; Wu, Jie

    2015-12-29

    Chlorophyll fluorometry may be used for detecting toxins in a sample because of changes in micro algae. A portable lab on a chip ("LOAC") based chlorophyll fluorometer may be used for toxin detection and environmental monitoring. In particular, the system may include a microfluidic pulse amplitude modulated ("PAM") chlorophyll fluorometer. The LOAC PAM chlorophyll fluorometer may analyze microalgae and cyanobacteria that grow naturally in source drinking water.

  10. Liquid scintillation counting of chlorophyll

    International Nuclear Information System (INIS)

    Fric, F.; Horickova, B.; Haspel-Horvatovic, E.

    1975-01-01

    A precise and reproducible method of liquid scintillation counting was worked out for measuring the radioactivity of 14 C-labelled chlorophyll a and chlorophyll b solutions without previous bleaching. The spurious count rate caused by luminescence of the scintillant-chlorophyll system is eliminated by using a suitable scintillant and by measuring the radioactivity at 4 to 8 0 C after an appropriate time of dark adaptation. Bleaching of the chlorophyll solutions is necessary only for measuring of very low radioactivity. (author)

  11. Revisiting the chlorophyll biosynthesis pathway using genome scale metabolic model of Oryza sativa japonica

    Science.gov (United States)

    Chatterjee, Ankita; Kundu, Sudip

    2015-01-01

    Chlorophyll is one of the most important pigments present in green plants and rice is one of the major food crops consumed worldwide. We curated the existing genome scale metabolic model (GSM) of rice leaf by incorporating new compartment, reactions and transporters. We used this modified GSM to elucidate how the chlorophyll is synthesized in a leaf through a series of bio-chemical reactions spanned over different organelles using inorganic macronutrients and light energy. We predicted the essential reactions and the associated genes of chlorophyll synthesis and validated against the existing experimental evidences. Further, ammonia is known to be the preferred source of nitrogen in rice paddy fields. The ammonia entering into the plant is assimilated in the root and leaf. The focus of the present work is centered on rice leaf metabolism. We studied the relative importance of ammonia transporters through the chloroplast and the cytosol and their interlink with other intracellular transporters. Ammonia assimilation in the leaves takes place by the enzyme glutamine synthetase (GS) which is present in the cytosol (GS1) and chloroplast (GS2). Our results provided possible explanation why GS2 mutants show normal growth under minimum photorespiration and appear chlorotic when exposed to air. PMID:26443104

  12. Site Energies of Active and Inactive Pheophytins in the Reaction Center of Photosystem II from Chlamydomonas Reinhardtii

    Energy Technology Data Exchange (ETDEWEB)

    Acharya, K.; Neupane, B.; Zazubovich, V.; Sayre, R. T.; Picorel, R.; Seibert, M.; Jankowiak, R.

    2012-03-29

    It is widely accepted that the primary electron acceptor in various Photosystem II (PSII) reaction center (RC) preparations is pheophytin {alpha} (Pheo {alpha}) within the D1 protein (Pheo{sub D1}), while Pheo{sub D2} (within the D2 protein) is photochemically inactive. The Pheo site energies, however, have remained elusive, due to inherent spectral congestion. While most researchers over the past two decades placed the Q{sub y}-states of Pheo{sub D1} and Pheo{sub D2} bands near 678-684 and 668-672 nm, respectively, recent modeling [Raszewski et al. Biophys. J. 2005, 88, 986-998; Cox et al. J. Phys. Chem. B 2009, 113, 12364-12374] of the electronic structure of the PSII RC reversed the assignment of the active and inactive Pheos, suggesting that the mean site energy of Pheo{sub D1} is near 672 nm, whereas Pheo{sub D2} ({approx}677.5 nm) and Chl{sub D1} ({approx}680 nm) have the lowest energies (i.e., the Pheo{sub D2}-dominated exciton is the lowest excited state). In contrast, chemical pigment exchange experiments on isolated RCs suggested that both pheophytins have their Q{sub y} absorption maxima at 676-680 nm [Germano et al. Biochemistry 2001, 40, 11472-11482; Germano et al. Biophys. J. 2004, 86, 1664-1672]. To provide more insight into the site energies of both Pheo{sub D1} and Pheo{sub D2} (including the corresponding Q{sub x} transitions, which are often claimed to be degenerate at 543 nm) and to attest that the above two assignments are most likely incorrect, we studied a large number of isolated RC preparations from spinach and wild-type Chlamydomonas reinhardtii (at different levels of intactness) as well as the Chlamydomonas reinhardtii mutant (D2-L209H), in which the active branch Pheo{sub D1} is genetically replaced with chlorophyll {alpha} (Chl {alpha}). We show that the Q{sub x}-/Q{sub y}-region site energies of Pheo{sub D1} and Pheo{sub D2} are {approx}545/680 nm and {approx}541.5/670 nm, respectively, in good agreement with our previous assignment

  13. Japan Nuclear Reaction Data Center (JCPRG), Faculty of Science, Hokkaido University, Steering Committee progress report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2007-11-15

    The Japan Nuclear Reaction Data Center (JCPRG) was approved as an organisation of Faculty of Science, Hokkaido University and established on April 1, 2007. In addition to nuclear data activities carried out by JCPRG (Japan-Charged Particle Nuclear Reaction Data Group), the centre is concerned with the evaluation of nuclear reaction data in nucleosynthesis in the universe. In order efficiently to compile reaction data obtained by using radioactive ion beam, the centre signed a research contract with RIKEN Nishina Center. We are scanning 16 journals for Japanese charged-particle and photo-nuclear nuclear reaction data compilation. From April 2006 to March 2007, CPND and PhND in 45 references (453 records, 1.83 MB) have been newly compiled for NRDF. Usually new data are released at the JCPRG web site several months prior to EXFOR. Since the 2006 NRDC meeting, we have made 104 new entries and have revised or deleted 142 old entries. Intensive numerical data compilations have been done. These data were shown in tabular form in dissertations which are (partially) published in Journals. About 30 new entries were compiled from these data. We have prepared CINDA batches for CPND published in Japan every half year. Each batch covers 6 issues of each of 4 Japanese journals JPJ, PTP, NST and JNRS. Bibliographies for neutron induced reaction data have been compiled by JAEA Nuclear Data Center as before. A new web-based NRDF search and plot system on MySQL was released in July, 2007. New compilation, which has been finalized for NRDF, but not for EXFOR, can be obtained from this site. DARPE (another NRDF search and plot system written in Perl) is also available at http://www.jcprg.org/darpe/. EXFOR/ENDF (http://www.jcprg.org/exfor/) search and plot system is available. We have also developed following utilities: PENDL (http://www.jcprg.org/endf/) and RENORM (http://www.jcprg.org/renorm). We are developing a new search system of CINDA. This is an extension of EXFOR/ENDF search

  14. Proton conduction within the reaction centers of Rhodobacter capsulatus: the electrostatic role of the protein.

    OpenAIRE

    Maróti, P; Hanson, D K; Baciou, L; Schiffer, M; Sebban, P

    1994-01-01

    Light-induced charge separation in the photosynthetic reaction center results in delivery of two electrons and two protons to the terminal quinone acceptor QB. In this paper, we have used flash-induced absorbance spectroscopy to study three strains that share identical amino acid sequences in the QB binding site, all of which lack the protonatable amino acids Glu-L212 and Asp-L213. These strains are the photosynthetically incompetent site-specific mutant Glu-L212/Asp-L213-->Ala-L212/Ala-L213 ...

  15. An efficient synthesis of α-amino-δ-valerolactones by the ugi five-center three-component reaction

    International Nuclear Information System (INIS)

    Kim, Young Bae; Lee, Duck Hyung; Park, Soo Jung; Keum, Gyo Chang; Jang, Min Seok; Kang, Soon Bang; Kim, You Seung

    2002-01-01

    A novel approach to α-amino-δ-valerolactones derivatives 8 by the intramolecular Ugi five-center three-component reaction (U-5C-3CR) using the multifunctional starting material, L-pentahomoserine 5 is described

  16. Engineered Photosystem II reaction centers optimize photochemistry versus photoprotection at different solar intensities.

    Science.gov (United States)

    Vinyard, David J; Gimpel, Javier; Ananyev, Gennady M; Mayfield, Stephen P; Dismukes, G Charles

    2014-03-12

    The D1 protein of Photosystem II (PSII) provides most of the ligating amino acid residues for the Mn4CaO5 water-oxidizing complex (WOC) and half of the reaction center cofactors, and it is present as two isoforms in the cyanobacterium Synechococcus elongatus PCC 7942. These isoforms, D1:1 and D1:2, confer functional advantages for photosynthetic growth at low and high light intensities, respectively. D1:1, D1:2, and seven point mutations in the D1:2 background that are native to D1:1 were expressed in the green alga Chlamydomonas reinhardtii. We used these nine strains to show that those strains that confer a higher yield of PSII charge separation under light-limiting conditions (where charge recombination is significant) have less efficient photochemical turnover, measured in terms of both a lower WOC turnover probability and a longer WOC cycle period. Conversely, these same strains under light saturation (where charge recombination does not compete) confer a correspondingly faster O2 evolution rate and greater protection against photoinhibition. Taken together, the data clearly establish that PSII primary charge separation is a trade-off between photochemical productivity (water oxidation and plastoquinone reduction) and charge recombination (photoprotection). These trade-offs add up to a significant growth advantage for the two natural isoforms. These insights provide fundamental design principles for engineering of PSII reaction centers with optimal photochemical efficiencies for growth at low versus high light intensities.

  17. Isolated photosystem I reaction centers on a functionalized gated high electron mobility transistor.

    Science.gov (United States)

    Eliza, Sazia A; Lee, Ida; Tulip, Fahmida S; Mostafa, Salwa; Greenbaum, Elias; Ericson, M Nance; Islam, Syed K

    2011-09-01

    In oxygenic plants, photons are captured with high quantum efficiency by two specialized reaction centers (RC) called Photosystem I (PS I) and Photosystem II (PS II). The captured photon triggers rapid charge separation and the photon energy is converted into an electrostatic potential across the nanometer-scale (~6 nm) reaction centers. The exogenous photovoltages from a single PS I RC have been previously measured using the technique of Kelvin force probe microscopy (KFM). However, biomolecular photovoltaic applications require two-terminal devices. This paper presents for the first time, a micro-device for detection and characterization of isolated PS I RCs. The device is based on an AlGaN/GaN high electron mobility transistor (HEMT) structure. AlGaN/GaN HEMTs show high current throughputs and greater sensitivity to surface charges compared to other field-effect devices. PS I complexes immobilized on the floating gate of AlGaN/GaN HEMTs resulted in significant changes in the device characteristics under illumination. An analytical model has been developed to estimate the RCs of a major orientation on the functionalized gate surface of the HEMTs. © 2011 IEEE

  18. Isolated Photosystem I Reaction Centers on a Functionalized Gated High Electron Mobility Transistor

    Energy Technology Data Exchange (ETDEWEB)

    Eliza, Sazia A. [University of Tennessee, Knoxville (UTK); Lee, Ida [ORNL; Tulip, Fahmida S [ORNL; Islam, Syed K [University of Tennessee, Knoxville (UTK); Mostafa, Salwa [University of Tennessee, Knoxville (UTK); Greenbaum, Elias [ORNL; Ericson, Milton Nance [ORNL

    2011-01-01

    In oxygenic plants, photons are captured with high quantum efficiency by two specialized reaction centers (RC) called Photosystem I (PS I) and Photosystem II (PS II). The captured photon triggers rapid charge separation and the photon energy is converted into an electrostatic potential across the nanometer-scale nm reaction centers. The exogenous photovoltages from a single PS I RC have been previously measured using the technique of Kelvin force probe microscopy (KFM). However, biomolecular photovoltaic applications require two-terminal devices. This paper presents for the first time, a micro-device for detection and characterization of isolated PS I RCs. The device is based on an AlGaN/GaN high electron mobility transistor (HEMT) structure. AlGaN/GaN HEMTs show high current throughputs and greater sensitivity to surface charges compared to other field-effect devices. PS I complexes immobilized on the floating gate of AlGaN/GaN HEMTs resulted in significant changes in the device characteristics under illumination. An analytical model has been developed to estimate the RCs of a major orientation on the functionalized gate surface of the HEMTs.

  19. How exciton-vibrational coherences control charge separation in the photosystem II reaction center.

    Science.gov (United States)

    Novoderezhkin, Vladimir I; Romero, Elisabet; van Grondelle, Rienk

    2015-12-14

    In photosynthesis absorbed sun light produces collective excitations (excitons) that form a coherent superposition of electronic and vibrational states of the individual pigments. Two-dimensional (2D) electronic spectroscopy allows a visualization of how these coherences are involved in the primary processes of energy and charge transfer. Based on quantitative modeling we identify the exciton-vibrational coherences observed in 2D photon echo of the photosystem II reaction center (PSII-RC). We find that the vibrations resonant with the exciton splittings can modify the delocalization of the exciton states and produce additional states, thus promoting directed energy transfer and allowing a switch between the two charge separation pathways. We conclude that the coincidence of the frequencies of the most intense vibrations with the splittings within the manifold of exciton and charge-transfer states in the PSII-RC is not occurring by chance, but reflects a fundamental principle of how energy conversion in photosynthesis was optimized.

  20. Chemical proprieties of the iron-quinone complex in mutated reaction centers of Rb. sphaeroides

    International Nuclear Information System (INIS)

    Hałas, Agnieszka; Derrien, Valerie; Sebban, Pierre; Matlak, Krzysztof; Korecki, Józef; Kruk, Jerzy; Burda, Kvĕtoslava

    2012-01-01

    We investigated type II bacterial photosynthetic reaction centers, which contain a quinone - iron complex (Q A -Fe-Q B ) on their acceptor side. Under physiological conditions it was observed mainly in a reduced high spin state but its low spin ferrous states were also observed. Therefore, it was suggested that it might regulate the dynamical properties of the iron–quinone complex and the protonation and deprotonation events in its neighbourhood. In order to get insight into the molecular mechanism of the NHFe low spin state formation, we preformed Mössbauer studies of a wild type of Rb. sphaeroides and its two mutated forms. Our Mössbauer measurements show that the hydrophobicity of the Q A binding site can be crucial for stabilization of the high spin ferrous state of NHFe.

  1. Alumina plate containing photosystem I reaction center complex oriented inside plate-penetrating silica nanopores.

    Science.gov (United States)

    Kamidaki, Chihiro; Kondo, Toru; Noji, Tomoyasu; Itoh, Tetsuji; Yamaguchi, Akira; Itoh, Shigeru

    2013-08-22

    The photosynthetic photosystem I reaction center complex (PSI-RC), which has a molecular diameter of 21 nm with 100 pigments, was incorporated into silica nanopores with a 100-nm diameter that penetrates an alumina plate of 60-μm thickness to make up an inorganic-biological hybrid photocell. PSI-RCs, purified from a thermophilic cyanobacterium, were stable inside the nanopores and rapidly photoreduced a mediator dye methyl viologen. The reduced dye was more stable inside nanopores suggesting the decrease of dissolved oxygen. The analysis by a cryogenic electron spin paramagnetic resonance indicated the oriented arrangement of RCs inside the 100-nm nanopores, with their surface parallel to the silica wall and perpendicular to the plane of the alumina plate. PSI RC complex in the semicrystalline orientation inside silica nanopores can be a new type of light energy conversion unit to supply strong reducing power selectively to other molecules inside or outside nanopores.

  2. Kinetics of several oxygenated carbon-centered free radical reactions with NO2.

    Science.gov (United States)

    Rissanen, Matti P; Arppe, Suula L; Timonen, Raimo S

    2013-05-16

    Five oxygenated carbon-centered free radical reactions with nitrogen dioxide (NO2) have been studied in direct time-resolved measurements. Experiments were conducted in a temperature-controlled flow tube reactor coupled to a 193 nm exciplex laser photolysis and a resonance gas lamp photoionization mass spectrometer. Reactions were investigated under pseudofirst-order conditions, with the NO2 concentrations of the experiments in great excess over the initial radical concentrations ([R]0 CH3CO radical reactions with NO2 and, hence, includes the three smallest hydroxyalkyl radical species (CH2OH, CH2CH2OH, and CH3CHOH). The obtained rate coefficients are high with the temperature-dependent rate coefficients given by a formula k(T) = k300K × (T/300 K)(-n) as (in units of cm(3) molecule(-1) s(-1)): k(CH2OH + NO2) = (8.95 ± 2.70) × 10(-11) × (T/300 K)(-0.54±0.27) (T = 298-363 K), k(CH2CH2OH + NO2) = (5.99 ± 1.80) × 10(-11) × (T/300 K)(-1.49±0.45)(T = 241-363 K), k(CH3CHOH + NO2) = (7.48 ± 2.24) × 10(-11) × (T/300 K)(-1.36±0.41) (T = 266-363 K), k(CH3OCH2 + NO2) = (7.85 ± 2.36) × 10(-11) × (T/300 K)(-0.93±0.28) (T = 243-363 K), and k(CH3CO + NO2) = (2.87 ± 0.57) × 10(-11) × (T/300 K)(-2.45±0.49) (T = 241-363 K), where the uncertainties refer to the estimated overall uncertainties of the values obtained. The determined rate coefficients show negative temperature dependence with no apparent bath gas pressure dependence under the current experimental conditions (241-363 K and about 1-3 Torr helium). This behavior is typical for a radical-radical addition mechanism with no potential energy barrier above the energy of the separated reactants in the entrance channel of the reaction. Unfortunately the absence of detected product signals prevented gaining deeper insight into the reaction mechanism.

  3. Interplay between excitation kinetics and reaction-center dynamics in purple bacteria

    International Nuclear Information System (INIS)

    Caycedo-Soler, Felipe; RodrIguez, Ferney J; Quiroga, Luis; Johnson, Neil F

    2010-01-01

    Photosynthesis is arguably the fundamental process of life, since it enables energy from the Sun to enter the food chain on the Earth. It is a remarkable non-equilibrium process in which photons are converted to many-body excitations, which traverse a complex biomolecular membrane, where they are captured and fuel chemical reactions within a reaction center (RC) in order to produce nutrients. The precise nature of these dynamical processes-which lie at the interface between quantum and classical behavior and involve both noise and coordination-is still being explored. Here, we focus on a striking recent empirical finding concerning an illumination-driven transition in the biomolecular membrane architecture of the purple bacteria Rsp. photometricum. Using stochastic realizations to describe a hopping rate model for excitation transfer, we show numerically and analytically that this surprising shift in preferred architectures can be traced to the interplay between the excitation kinetics and the RC dynamics. The net effect is that the bacteria profit from efficient metabolism at low illumination intensities while using dissipation to avoid an oversupply of energy at high illumination intensities.

  4. Center of gravity estimation using a reaction board instrumented with fiber Bragg gratings

    Science.gov (United States)

    Oliveira, Rui; Roriz, Paulo; Marques, Manuel B.; Frazão, Orlando

    2018-03-01

    The purpose of the present work is to construct a reaction board based on fiber Bragg gratings (FBGs) that could be used for estimation of the 2D coordinates of the projection of center of gravity (CG) of an object. The apparatus is consisted of a rigid equilateral triangular board mounted on three supports at the vertices, two of which have cantilevers instrumented with FBGs. When an object of known weight is placed on the board, the bending strain of the cantilevers is measured by a proportional wavelength shift of the FBGs. Applying the equilibrium conditions of a rigid body and proper calibration procedures, the wavelength shift is used to estimate the vertical reaction forces and moments of force at the supports and the coordinates of the object's CG projection on the board. This method can be used on a regular basis to estimate the CG of the human body or objects with complex geometry and density distribution. An example is provided for the estimation of the CG projection coordinates of two orthopaedic femur bone models, one intact, and the other with a hip stem implant encased. The clinical implications of changing the normal CG location by means of a prosthesis have been discussed.

  5. Protein sequences and redox titrations indicate that the electron acceptors in reaction centers from heliobacteria are similar to Photosystem I

    Science.gov (United States)

    Trost, J. T.; Brune, D. C.; Blankenship, R. E.

    1992-01-01

    Photosynthetic reaction centers isolated from Heliobacillus mobilis exhibit a single major protein on SDS-PAGE of 47 000 Mr. Attempts to sequence the reaction center polypeptide indicated that the N-terminus is blocked. After enzymatic and chemical cleavage, four peptide fragments were sequenced from the Heliobacillus mobilis apoprotein. Only one of these sequences showed significant specific similarity to any of the protein and deduced protein sequences in the GenBank data base. This fragment is identical with 56% of the residues, including both cysteines, found in highly conserved region that is proposed to bind iron-sulfur center Fx in the Photosystem I reaction center peptide that is the psaB gene product. The similarity to the psaA gene product in this region is 48%. Redox titrations of laser-flash-induced photobleaching with millisecond decay kinetics on isolated reaction centers from Heliobacterium gestii indicate a midpoint potential of -414 mV with n = 2 titration behavior. In membranes, the behavior is intermediate between n = 1 and n = 2, and the apparent midpoint potential is -444 mV. This is compared to the behavior in Photosystem I, where the intermediate electron acceptor A1, thought to be a phylloquinone molecule, has been proposed to undergo a double reduction at low redox potentials in the presence of viologen redox mediators. These results strongly suggest that the acceptor side electron transfer system in reaction centers from heliobacteria is indeed analogous to that found in Photosystem I. The sequence similarities indicate that the divergence of the heliobacteria from the Photosystem I line occurred before the gene duplication and subsequent divergence that lead to the heterodimeric protein core of the Photosystem I reaction center.

  6. Acute toxicity of excess mercury on the photosynthetic performance of cyanobacterium, S. platensis--assessment by chlorophyll fluorescence analysis.

    Science.gov (United States)

    Lu, C M; Chau, C W; Zhang, J H

    2000-07-01

    Measurement of chlorophyll fluorescence has been shown to be a rapid, non-invasive, and reliable method to assess photosynthetic performance in a changing environment. In this study, acute toxicity of excess Hg on the photosynthetic performance of the cyanobacterium S. platensis, was investigated by use of chlorophyll fluorescence analysis after cells were exposed to excess Hg (up to 20 microM) for 2 h. The results determined from the fast fluorescence kinetics showed that Hg induced a significant increase in the proportion of the Q(B)-non-reducing PSII reaction centers. The fluorescence parameters measured under the steady state of photosynthesis demonstrated that the increase of Hg concentration led to a decrease in the maximal efficiency of PSII photochemistry, the efficiency of excitation energy capture by the open PSII reaction centers, and the quantum yield of PSII electron transport. Mercury also resulted in a decrease in the coefficients of photochemical and non-photochemical quenching. Mercury may have an acute toxicity on cyanobacteria by inhibiting the quantum yield of photosynthesis sensitively and rapidly. Such changes occurred before any other visible damages that may be evaluated by other conventional measurements. Our results also demonstrated that chlorophyll fluorescence analysis can be used as a useful physiological tool to assess early stages of change in photosynthetic performance of algae in response to heavy metal pollution.

  7. Evaluation of Chlorophyll Content and Chlorophyll Fluorescence Parameters and Relationships between Chlorophyll a, b and Chlorophyll Content Index under Water Stress in Olea europaea cv. Dezful

    OpenAIRE

    E. Khaleghi; K. Arzani; N. Moallemi; M. Barzegar

    2012-01-01

    This study was conducted to determine effect of water stress on chlorophyll content and chlorophyll fluorescence parameter in young `Dezful- olive trees. Three irrigation regimes (40% ETcrop, 65% ETcrop and 100% ETcrop) were used. After irrigation treatments were applied, some of biochemical parameters including chlorophyll a, b, total chlorophyll, chlorophyll fluorescence and also chlorophyll content index (C.C.I) were measured. Results of Analysis of variance showed that irrigation treatmen...

  8. Bacterial Reaction Centers Purified with Styrene Maleic Acid Copolymer Retain Native Membrane Functional Properties and Display Enhanced Stability**

    Science.gov (United States)

    Swainsbury, David J K; Scheidelaar, Stefan; van Grondelle, Rienk; Killian, J Antoinette; Jones, Michael R

    2014-01-01

    Integral membrane proteins often present daunting challenges for biophysical characterization, a fundamental issue being how to select a surfactant that will optimally preserve the individual structure and functional properties of a given membrane protein. Bacterial reaction centers offer a rare opportunity to compare the properties of an integral membrane protein in different artificial lipid/surfactant environments with those in the native bilayer. Here, we demonstrate that reaction centers purified using a styrene maleic acid copolymer remain associated with a complement of native lipids and do not display the modified functional properties that typically result from detergent solubilization. Direct comparisons show that reaction centers are more stable in this copolymer/lipid environment than in a detergent micelle or even in the native membrane, suggesting a promising new route to exploitation of such photovoltaic integral membrane proteins in device applications. PMID:25212490

  9. [High activity antiretroviral therapy change associated to adverse drug reactions in a specialized center in Venezuela].

    Science.gov (United States)

    Subiela, José D; Dapena, Elida

    2016-03-01

    Adverse drug reactions (ADRs) represent the first cause of change of the first-line highly active antiretroviral therapy (HAART) regimen, therefore, they constitute the main limiting factor in the long-term follow up of HIV patients in treatment. A retrospective study was carried out in a specialized center in Lara State, Venezuela, including 99 patients over 18 years of age who had change of first-line HAART regimen due to ADRs, between 2010 and 2013. The aims of this research were to describe the sociodemographic and clinical variables, frequency of ADRs related to change of HAART, duration of the first-line HAART regimen, to determine the drugs associated with ARVs and to identify the risk factors. The ADRs constituted 47.5% of all causes of change of first-line HAART regimen, the median duration was 1.08±0.28 years. The most frequent ADRs were anemia (34.3%), hypersensitivity reactions (20.2%) and gastrointestinal intolerance (13.1%). The most frequent ARV regimen type was the protease inhibitors-based regimen (59.6%), but zidovudine was the ARV most linked to ADRs (41.4%). The regression analysis showed increased risk of ADRs in singles and students in the univariate analysis and heterosexuals and homosexuals in multivariate analysis; and decreased risk in active workers. The present work shows the high prevalence of ADRs in the studied population and represents the first case-based study that describes the pharmacoepidemiology of a cohort of HIV-positive patients treated in Venezuela.

  10. Proton conduction within the reaction centers of Rhodobacter capsulatus: the electrostatic role of the protein.

    Science.gov (United States)

    Maróti, P; Hanson, D K; Baciou, L; Schiffer, M; Sebban, P

    1994-06-07

    Light-induced charge separation in the photosynthetic reaction center results in delivery of two electrons and two protons to the terminal quinone acceptor QB. In this paper, we have used flash-induced absorbance spectroscopy to study three strains that share identical amino acid sequences in the QB binding site, all of which lack the protonatable amino acids Glu-L212 and Asp-L213. These strains are the photosynthetically incompetent site-specific mutant Glu-L212/Asp-L213-->Ala-L212/Ala-L213 and two different photocompetent derivatives that carry both alanine substitutions and an intergenic suppressor mutation located far from QB (class 3 strain, Ala-Ala + Arg-M231-->Leu; class 4 strain, Ala-Ala + Asn-M43-->Asp). At pH 8 in the double mutant, we observe a concomitant decrease of nearly 4 orders of magnitude in the rate constants of second electron and proton transfer to QB compared to the wild type. Surprisingly, these rates are increased to about the same extent in both types of suppressor strains but remain > 2 orders of magnitude smaller than those of the wild type. In the double mutant, at pH 8, the loss of Asp-L213 and Glu-L212 leads to a substantial stabilization (> or = 60 meV) of the semiquinone energy level. Both types of compensatory mutations partially restore, to nearly the same level, the original free energy difference for electron transfer from primary quinone QA to QB. The pH dependence of the electron and proton transfer processes in the double-mutant and the suppressor strains suggests that when reaction centers of the double mutant are shifted to lower pH (1.5-2 units), they function like those of the suppressor strains at physiological pH. Our data suggest that the main effect of the compensatory mutations is to partially restore the negative electrostatic environment of QB and to increase an apparent "functional" pK of the system for efficient proton transfer to the active site. This emphasizes the role of the protein in tuning the

  11. [On the influence of local molecular environment on the redox potential of electron transfer cofactors in bacterial photosynthetic reaction centers].

    Science.gov (United States)

    Krasil'nikov, P M; Noks, P P; Rubin, A B

    2011-01-01

    The addition of cryosolvents (glycerol, dimethylsulfoxide) to a water solution containing bacterial photosynthetic reaction centers changes the redox potential of the bacteriochlorophyll dimer, but does not affect the redox potential of the quinone primary acceptor. It has been shown that the change in redox potential can be produced by changes of the electrostatic interactions between cofactors and the local molecular environment modified by additives entered into the solution. The degree of influence of a solvent on the redox potential of various cofactors is determined by degree of availability of these cofactors for molecules of solvent, which depends on the arrangement of cofactors in the structure of reaction centers.

  12. Instability of chlorophyll in yellow lupin seedlings grown in soil contaminated with ciprofloxacin and tetracycline.

    Science.gov (United States)

    Rydzyński, Dariusz; Piotrowicz-Cieślak, Agnieszka I; Grajek, Hanna; Michalczyk, Dariusz J

    2017-10-01

    With increasing soil concentrations of ciprofloxacin and tetracycline a decrease of leaf chlorophyll content was observed. Tetracycline was more detrimental than ciprofloxacin. The chlorophyll content in plants growing for ten days on a tetracycline containing soil decreased by 68%. The decrease of chlorophyll concentration was even sharper in new leaves that formed after application of the antibiotic (up to 81% drop). The comparison of absorption spectra of commercial, reagent grade chlorophyll, alone and incubated with antibiotics, has shown that ciprofloxacin and tetracycline can react directly with chlorophyll and decrease its concentration by 47.7% and 48.5%, respectively. The changes in fluorescence spectra confirmed the formation of chlorophyll degradation product. The chlorophyll decay was a second order reaction and depended on antibiotic concentration and duration of exposure. Reaction rate constants differed with antibiotics and their soil concentrations. With increasing contents of antibiotics in soil the constant of chlorophyll degradation rate in lupin plants increased from k = 870 M -1 day -1 for 3 mg ciprofloxacin to k = 2490 M -1 day -1 for 90 mg ciprofloxacin, and in the case of tetracycline the reaction rate constant increased from k = 1330 M -1 day -1 to k = 2910 M -1 day -1 . The sensitivity of chlorophyll to ciprofloxacin and tetracycline was confirmed by determining EC and TU indices. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Kinetics of Several Oxygen-Containing Carbon-Centered Free Radical Reactions with Nitric Oxide.

    Science.gov (United States)

    Rissanen, Matti P; Ihlenborg, Marvin; Pekkanen, Timo T; Timonen, Raimo S

    2015-07-16

    Kinetics of four carbon-centered, oxygen-containing free radical reactions with nitric oxide (NO) were investigated as a function of temperature at a few Torr pressure of helium, employing flow tube reactors coupled to a laser-photolysis/resonance-gas-discharge-lamp photoionization mass spectrometer (LP-RPIMS). Rate coefficients were directly determined from radical (R) decay signals under pseudo-first-order conditions ([R]0 ≪ [NO]). The obtained rate coefficients showed negative temperature dependences, typical for a radical-radical association process, and can be represented by the following parametrizations (all in units of cm(3) molecule(-1) s(-1)): k(CH2OH + NO) = (4.76 × 10(-21)) × (T/300 K)(15.92) × exp[50700/(RT)] (T = 266-363 K, p = 0.79-3.44 Torr); k(CH3CHOH + NO) = (1.27 × 10(-16)) × (T/300 K)(6.81) × exp[28700/(RT)] (T = 241-363 K, p = 0.52-3.43 Torr); k(CH3OCH2 + NO) = (3.58 ± 0.12) × 10(-12) × (T/300 K)(-3.17±0.14) (T = 221-363 K, p = 0.50-0.80 Torr); k(T)3 = 9.62 × 10(-11) × (T/300 K)(-5.99) × exp[-7100/(RT)] (T = 221-473 K, p = 1.41-2.95 Torr), with the uncertainties given as standard errors of the fits and the overall uncertainties estimated as ±20%. The rate of CH3OCH2 + NO reaction was measured in two density ranges due to its observed considerable pressure dependence, which was not found in the studied hydroxyalkyl reactions. In addition, the CH3CO + NO rate coefficient was determined at two temperatures resulting in k298K(CH3CO + NO) = (5.6 ± 2.8) × 10(-13) cm(3) molecule(-1) s(-1). No products were found during these experiments, reasons for which are briefly discussed.

  14. Assembly of photosynthetic reaction center with ABA tri-block polymersomes: highlights on the protein localization.

    KAUST Repository

    Tangorra, Roberto Rocco

    2015-07-07

    The reconstitution of the integral membrane protein photosynthetic reaction center (RC) in polymersomes, i. e. artificial closed vesicles, was achieved by the micelle-to-vesicle transition technique, a very mild protocol based on size exclusion chromatography often used to drive the incorporation of proteins contemporarily to liposomes formation. An optimized protocol was used to successfully reconstitute the protein in a fully active state in polymersomes formed by the tri-block copolymers PMOXA22-PDMS61-PMOXA22. The RC is very sensitive to its solubilizing environment and was used to probe the positioning of the protein in the vesicles. According to charge-recombination experiments and to the enzymatic activity assay, the RC is found to accommodate in the PMOXA22 region of the polymersome, facing the water bulk solution, rather than in the PDMS61 transmembrane-like region. Furthermore, polymersomes were found to preserve protein integrity efficiently as the biomimetic lipid bilayers but show a much longer temporal stability than lipid based vesicles.

  15. Early bacteriopheophytin reduction in charge separation in reaction centers of Rhodobacter sphaeroides.

    Science.gov (United States)

    Zhu, Jingyi; van Stokkum, Ivo H M; Paparelli, Laura; Jones, Michael R; Groot, Marie Louise

    2013-06-04

    A question at the forefront of biophysical sciences is, to what extent do quantum effects and protein conformational changes play a role in processes such as biological sensing and energy conversion? At the heart of photosynthetic energy transduction lie processes involving ultrafast energy and electron transfers among a small number of tetrapyrrole pigments embedded in the interior of a protein. In the purple bacterial reaction center (RC), a highly efficient ultrafast charge separation takes place between a pair of bacteriochlorophylls: an accessory bacteriochlorophyll (B) and bacteriopheophytin (H). In this work, we applied ultrafast spectroscopy in the visible and near-infrared spectral region to Rhodobacter sphaeroides RCs to accurately track the timing of the electron on BA and HA via the appearance of the BA and HA anion bands. We observed an unexpectedly early rise of the HA⁻ band that challenges the accepted simple picture of stepwise electron transfer with 3 ps and 1 ps time constants. The implications for the mechanism of initial charge separation in bacterial RCs are discussed in terms of a possible adiabatic electron transfer step between BA and HA, and the effect of protein conformation on the electron transfer rate. Copyright © 2013 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  16. Fragment molecular orbital study on electron tunneling mechanisms in bacterial photosynthetic reaction center.

    Science.gov (United States)

    Kitoh-Nishioka, Hirotaka; Ando, Koji

    2012-11-01

    The tunneling mechanisms of electron transfers (ETs) in photosynthetic reaction center of Blastochloris viridis are studied by the ab initio fragment molecular orbital (FMO) method combined with the generalized Mulliken-Hush (GMH) and the bridge Green function (GF) calculations of the electronic coupling T(DA) and the tunneling current method for the ET pathway analysis at the fragment-based resolution. For the ET from batctriopheophytin (H(L)) to menaquinone (MQ), a major tunneling current through Trp M250 and a minor back flow via Ala M215, Ala M216, and His M217 are quantified. For the ET from MQ to ubiquinone, the major tunneling pathway via the nonheme Fe(2+) and His L190 is identified as well as minor pathway via His M217 and small back flows involving His L230, Glu M232, and His M264. At the given molecular structure from X-ray experiment, the spin state of the Fe(2+) ion, its replacement by Zn(2+), or its removal are found to affect the T(DA) value by factors within 2.2. The calculated T(DA) values, together with experimentally estimated values of the driving force and the reorganization energy, give the ET rates in reasonable agreement with experiments.

  17. Assembly of photosynthetic reaction center with ABA tri-block polymersomes: highlights on the protein localization.

    KAUST Repository

    Tangorra, Roberto Rocco; Operamolla, Alessandra; Milano, Francesco; Hassan Omar, Omar; Henrard, John; Comparelli, Roberto; Italiano, Francesca; Agostiano, Angela; De Leo, Vincenzo; Marotta, Roberto; Falqui, Andrea; Farinola, Gianluca; Trotta, Massimo

    2015-01-01

    The reconstitution of the integral membrane protein photosynthetic reaction center (RC) in polymersomes, i. e. artificial closed vesicles, was achieved by the micelle-to-vesicle transition technique, a very mild protocol based on size exclusion chromatography often used to drive the incorporation of proteins contemporarily to liposomes formation. An optimized protocol was used to successfully reconstitute the protein in a fully active state in polymersomes formed by the tri-block copolymers PMOXA22-PDMS61-PMOXA22. The RC is very sensitive to its solubilizing environment and was used to probe the positioning of the protein in the vesicles. According to charge-recombination experiments and to the enzymatic activity assay, the RC is found to accommodate in the PMOXA22 region of the polymersome, facing the water bulk solution, rather than in the PDMS61 transmembrane-like region. Furthermore, polymersomes were found to preserve protein integrity efficiently as the biomimetic lipid bilayers but show a much longer temporal stability than lipid based vesicles.

  18. Redox potential tuning through differential quinone binding in the photosynthetic reaction center of Rhodobacter sphaeroides.

    Science.gov (United States)

    Vermaas, Josh V; Taguchi, Alexander T; Dikanov, Sergei A; Wraight, Colin A; Tajkhorshid, Emad

    2015-03-31

    Ubiquinone forms an integral part of the electron transport chain in cellular respiration and photosynthesis across a vast number of organisms. Prior experimental results have shown that the photosynthetic reaction center (RC) from Rhodobacter sphaeroides is only fully functional with a limited set of methoxy-bearing quinones, suggesting that specific interactions with this substituent are required to drive electron transport and the formation of quinol. The nature of these interactions has yet to be determined. Through parameterization of a CHARMM-compatible quinone force field and subsequent molecular dynamics simulations of the quinone-bound RC, we have investigated and characterized the interactions of the protein with the quinones in the Q(A) and Q(B) sites using both equilibrium simulation and thermodynamic integration. In particular, we identify a specific interaction between the 2-methoxy group of ubiquinone in the Q(B) site and the amide nitrogen of GlyL225 that we implicate in locking the orientation of the 2-methoxy group, thereby tuning the redox potential difference between the quinones occupying the Q(A) and Q(B) sites. Disruption of this interaction leads to weaker binding in a ubiquinone analogue that lacks a 2-methoxy group, a finding supported by reverse electron transfer electron paramagnetic resonance experiments of the Q(A)⁻Q(B)⁻ biradical and competitive binding assays.

  19. Purification and spectroscopic characterization of photosystem II reaction center complexes isolated with or without Triton X-100.

    NARCIS (Netherlands)

    Eijckelhoff, C.; van Roon, H.; Groot, M.L.; van Grondelle, R.; Dekker, J.P.

    1996-01-01

    The pigment composition of the isolated photosystem II reaction center complex in its most stable and pure form currently is a matter of considerable debate. In this contribution, we present a new method based on a combination of gel filtration chromatography and diode array detection to analyze the

  20. Report on the consultants` meeting on technical aspects of the co-operation of nuclear reaction data centers

    Energy Technology Data Exchange (ETDEWEB)

    Lemmel, H D; Schwerer, O; Wienke, H [eds.

    1995-10-01

    The IAEA Nuclear Data Section convenes in annual intervals coordination meetings of the Network of the Nuclear Reaction Data Center. The present meeting dealt with technical matters of the nuclear data compilation and exchange by means of the jointly operated computerized systems CINDA, EXFOR, ENDF and others. Refs, figs and tabs.

  1. A new pathway for transmembrane electron transfer in photosynthetic reaction centers of Rhodobacter sphaeroides not involving the excited special pair.

    NARCIS (Netherlands)

    van Brederode, M.E.; Jones, M.R.; van Mourik, F.; van Stokkum, I.H.M.; van Grondelle, R.

    1997-01-01

    It is generally accepted that electron transfer in bacterial photosynthesis is driven by the first singlet excited state of a special pair of bacteriochlorophylls (P*). We have examined the first steps of electron transfer in a mutant of the Rhodobacter sphaeroides reaction center in which charge

  2. A new pathway for transmembrane electron transfer in photosyntetic reaction centers of Rhodobacter sphaeroides not involving the excited special pair.

    NARCIS (Netherlands)

    van Brederode, M.E.; Jones, M.R.; van Mourik, F.; van Stokkum, I.H.M.; van Grondelle, R.

    1997-01-01

    It is generally accepted that electron transfer in bacterial photosynthesis is driven by the first singlet excited state of a special pair of bacteriochlorophylls (P*). We have examined the first steps of electron transfer in a mutant of the Rhodobacter sphaeroides reaction center in which charge

  3. Report on the consultants' meeting on technical aspects of the co-operation of nuclear reaction data centers

    International Nuclear Information System (INIS)

    Lemmel, H.D.; Schwerer, O.; Wienke, H.

    1995-10-01

    The IAEA Nuclear Data Section convenes in annual intervals coordination meetings of the Network of the Nuclear Reaction Data Center. The present meeting dealt with technical matters of the nuclear data compilation and exchange by means of the jointly operated computerized systems CINDA, EXFOR, ENDF and others. Refs, figs and tabs

  4. Thermotolerance of apple tree leaves probed by chlorophyll a fluorescence and modulated 820 nm reflection during seasonal shift.

    Science.gov (United States)

    Duan, Ying; Zhang, Mengxia; Gao, Jin; Li, Pengmin; Goltsev, Vasilij; Ma, Fengwang

    2015-11-01

    During the seasonal shift from June to August, air temperatures increase. To explore how apple trees improve their thermotolerance during this shift, we examined the photochemical reaction capacity of apple tree leaves by simultaneous measurement of prompt chlorophyll fluorescence, delayed chlorophyll fluorescence, and modulated 820 nm reflection at varying temperatures. It was found that the reaction centers and antennae of photosystem II (PSII) and photosystem I (PSI), the donor side of PSII, the electron transfer capacity from QA to QB, and the reoxidation capacity of plastoquinol were all sensitive to heat stress, particularly in June. As the season shifted, apple tree leaves improved in thermotolerance. Interestingly, the acclimation to seasonal shift enhanced the thermotolerance of PSII and PSI reaction centers more than that of their antennae, and the activity of PSII more than that of PSI. This may be a strategy for plant adaptation to changes in environmental temperatures. In addition, results from prompt and delayed fluorescence, as well as modulated 820 nm reflection corroborate each other. We suggest that the simultaneous measurement of the three independent signals may provide more information on thermal acclimation mechanisms of photochemical reactions in plant leaves. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Utilizing the dynamic stark shift as a probe for dielectric relaxation in photosynthetic reaction centers during charge separation.

    Science.gov (United States)

    Guo, Zhi; Lin, Su; Woodbury, Neal W

    2013-09-26

    In photosynthetic reaction centers, the electric field generated by light-induced charge separation produces electrochromic shifts in the transitions of reaction center pigments. The extent of this Stark shift indirectly reflects the effective field strength at a particular cofactor in the complex. The dynamics of the effective field strength near the two monomeric bacteriochlorophylls (BA and BB) in purple photosynthetic bacterial reaction centers has been explored near physiological temperature by monitoring the time-dependent Stark shift during charge separation (dynamic Stark shift). This dynamic Stark shift was determined through analysis of femtosecond time-resolved absorbance change spectra recorded in wild type reaction centers and in four mutants at position M210. In both wild type and the mutants, the kinetics of the dynamic Stark shift differ from those of electron transfer, though not in the same way. In wild type, the initial electron transfer and the increase in the effective field strength near the active-side monomer bacteriochlorophyll (BA) occur in synchrony, but the two signals diverge on the time scale of electron transfer to the quinone. In contrast, when tyrosine is replaced by aspartic acid at M210, the kinetics of the BA Stark shift and the initial electron transfer differ, but transfer to the quinone coincides with the decay of the Stark shift. This is interpreted in terms of differences in the dynamics of the local dielectric environment between the mutants and the wild type. In wild type, comparison of the Stark shifts associated with BA and BB on the two quasi-symmetric halves of the reaction center structure confirm that the effective dielectric constants near these cofactors are quite different when the reaction center is in the state P(+)QA(-), as previously determined by Steffen et al. at 1.5 K (Steffen, M. A.; et al. Science 1994, 264, 810-816). However, it is not possible to determine from static, low-temperature measurments if the

  6. Comparison of Ground Reaction Forces, Center of Pressure and Body Center of Mass Changes in the Voluntary, Semi-Voluntary and Involuntary Gait Termination in Healthy Young Men

    Directory of Open Access Journals (Sweden)

    behrooz teymourian

    2016-03-01

    Full Text Available Objective: The aim of this study was comparing the ground reaction forces, center of pressure and body center of mass changes in voluntary, semi-voluntary and involuntary gait termination in healthy young men. Methods: In this study, 12 young men performed termination of gait in three different patterns. The variable of peak antero-posterior and vertical forces in two directions at both limbs, the time to reach peak and average forces in every limb in both directions, the center of pressure displacement of medio-lateral and antero-posterior direction for each limb and the net center of pressure and the displacement of the center of mass motion in all three motion plates were recorded using motion analysis system and force plate.The repeated measurements test was used to compare three patterns of gait termination at significance level of p&le0.5. Results: The results showed a significant difference in variables of peak antero-posterior force, the time to reach peak antero-posterior force and mean antero-posterior forces of the leading limb, the peak antero-posterior force of the trialing limbs, the depth force of leading limbs, medio-lateral cop of leading limbs displacement and vertical displacement of the center of mass, among different patterns of gait termination. Conclusion: While walking, the probability of a fall or collision damage, when a sudden or unexpected stop is required, increases. Therefore, more coordination between neuromuscular systems is required.

  7. Photosynthetic bark: use of chlorophyll absorption continuum index to estimate Boswellia papyrifera bark chlorophyll content

    NARCIS (Netherlands)

    Girma, A.; Skidmore, A.K.; Bie, de C.A.J.M.; Bongers, F.; Schlerf, M.

    2013-01-01

    Quantification of chlorophyll content provides useful insight into the physiological performance of plants. Several leaf chlorophyll estimation techniques, using hyperspectral instruments, are available. However, to our knowledge, a non-destructive bark chlorophyll estimation technique is not

  8. Photosynthetic bark : use of chlorophyll absorption continuum index to estimate Boswellia papyrifera bark chlorophyll content

    NARCIS (Netherlands)

    Girma Gebrekidan, A.; Skidmore, A.K.; de Bie, C.A.J.M.; Bongers, Frans; Schlerf, Martin; Schlerf, M.

    2013-01-01

    Quantification of chlorophyll content provides useful insight into the physiological performance of plants. Several leaf chlorophyll estimation techniques, using hyperspectral instruments, are available. However, to our knowledge, a non-destructive bark chlorophyll estimation technique is not

  9. Quinone reduction via secondary B-branch electron transfer in mutant bacterial reaction centers.

    Science.gov (United States)

    Laible, Philip D; Kirmaier, Christine; Udawatte, Chandani S M; Hofman, Samuel J; Holten, Dewey; Hanson, Deborah K

    2003-02-18

    Symmetry-related branches of electron-transfer cofactors-initiating with a primary electron donor (P) and terminating in quinone acceptors (Q)-are common features of photosynthetic reaction centers (RC). Experimental observations show activity of only one of them-the A branch-in wild-type bacterial RCs. In a mutant RC, we now demonstrate that electron transfer can occur along the entire, normally inactive B-branch pathway to reduce the terminal acceptor Q(B) on the time scale of nanoseconds. The transmembrane charge-separated state P(+)Q(B)(-) is created in this manner in a Rhodobacter capsulatus RC containing the F(L181)Y-Y(M208)F-L(M212)H-W(M250)V mutations (YFHV). The W(M250)V mutation quantitatively blocks binding of Q(A), thereby eliminating Q(B) reduction via the normal A-branch pathway. Full occupancy of the Q(B) site by the native UQ(10) is ensured (without the necessity of reconstitution by exogenous quinone) by purification of RCs with the mild detergent, Deriphat 160-C. The lifetime of P(+)Q(B)(-) in the YFHV mutant RC is >6 s (at pH 8.0, 298 K). This charge-separated state is not formed upon addition of competitive inhibitors of Q(B) binding (terbutryn or stigmatellin). Furthermore, this lifetime is much longer than the value of approximately 1-1.5 s found when P(+)Q(B)(-) is produced in the wild-type RC by A-side activity alone. Collectively, these results demonstrate that P(+)Q(B)(-) is formed solely by activity of the B-branch carriers in the YFHV RC. In comparison, P(+)Q(B)(-) can form by either the A or B branches in the YFH RC, as indicated by the biexponential lifetimes of approximately 1 and approximately 6-10 s. These findings suggest that P(+)Q(B)(-) states formed via the two branches are distinct and that P(+)Q(B)(-) formed by the B side does not decay via the normal (indirect) pathway that utilizes the A-side cofactors when present. These differences may report on structural and energetic factors that further distinguish the functional

  10. Report compiled by Research Center for Carbonaceous Resources, Institute for Chemical Reaction Science, Tohoku University; Tohoku Daigaku Hanno Kagaku Kenkyusho tanso shigen hanno kenkyu center hokokusho

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1994-04-01

    The Research Center for Carbonaceous Resources was established in April 1991 for the purpose of developing a comprehensive process for converting carbonaceous resources into clean fuels or into materials equipped with advanced functions. In this report, the track records etc. of the center are introduced. Under study in the conversion process research department is the organization of a comprehensive coal conversion process which will be a combination of solvent extraction, catalytic decomposition, and catalytic gasification, whose goal is to convert coal in a clean way at high efficiency. Under study in the conversion catalyst research department are the development of a coal denitrogenation method, development of a low-temperature gasification method by use of inexpensive catalysts, synthesis of C{sub 2} hydrocarbons in a methane/carbon dioxide reaction, etc. Other endeavors under way involve the designing and development of new organic materials such as new carbon materials and a study of the foundation on which such efforts stand, that is, the study of the control of reactions between solids. Furthermore, in the study of interfacial reaction control, the contact gasification of coal, brown coal ion exchange capacity and surface conditions, carbonization of cation exchanged brown coal, etc., are being developed. (NEDO)

  11. Photochemistry and reactions of OH- defects and F centers in alkali halides

    International Nuclear Information System (INIS)

    Morato, S.P.; Luety, F.

    1978-01-01

    Aditively colored KCl:OH - crystals showed under a combined UV and VIS irradiation, a nearly complete and irreversible destruction of all F centers and visible absorption in the crystal. Only upon heating the crystal above 650 0 C the F center coloration becomes partially restored. The photodissociation of the OH - (under UV light) together with the photoionization of the F center (under VIS light) produces a not effects where all the F centers are converted into U centers. These photoreactions produces high contrast visible images that are completely stable under light at RT. Besides the optical information storage aspect of this effect these photoreaction s can also be used for controlled production of Usub(A) centers if the crystal also contains a foreign metallic impurity such a Na + ion [pt

  12. On the nature of organic and inorganic centers that bifurcate electrons, coupling exergonic and endergonic oxidation-reduction reactions.

    Science.gov (United States)

    Peters, John W; Beratan, David N; Schut, Gerrit J; Adams, Michael W W

    2018-04-19

    Bifurcating electrons to couple endergonic and exergonic electron-transfer reactions has been shown to have a key role in energy conserving redox enzymes. Bifurcating enzymes require a redox center that is capable of directing electron transport along two spatially separate pathways. Research into the nature of electron bifurcating sites indicates that one of the keys is the formation of a low potential oxidation state to satisfy the energetics required of the endergonic half reaction, indicating that any redox center (organic or inorganic) that can exist in multiple oxidation states with sufficiently separated redox potentials should be capable of electron bifurcation. In this Feature Article, we explore a paradigm for bifurcating electrons down independent high and low potential pathways, and describe redox cofactors that have been demonstrated or implicated in driving this unique biochemistry.

  13. Reaction

    African Journals Online (AJOL)

    abp

    19 oct. 2017 ... Reaction to Mohamed Said Nakhli et al. concerning the article: "When the axillary block remains the only alternative in a 5 year old child". .... Bertini L1, Savoia G, De Nicola A, Ivani G, Gravino E, Albani A et al ... 2010;7(2):101-.

  14. Glial reaction in visual centers upon whole-body combined irradiation with microwaves and x-radiation

    International Nuclear Information System (INIS)

    Logvinov, S.V.

    1989-01-01

    A single whole-body preirradiation with thermogenous microwaves modifies the dynamics of the glial reactions of visual centers of ginea pigs induced by median lethal X-radiation doses. A combination of the two factors products the synergistic effect, estimated by the degree of alteration of astrocytes and oligodendroglyocytes at early times after exposure, leads to early activation of microglia, and reduces radiation-induced alterations in glia at later times (25-60 days)

  15. The magnesium chelation step in chlorophyll biosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Weinstein, J.D.

    1991-01-01

    The biogenesis of energy transducing membranes requires the coordinate synthesis of prosthetic groups, proteins and lipids. Two of the major prosthetic groups, chlorophyll and heme, share a common biosynthetic pathway that diverges at the point of metal insertion into protoporphyrin IX. Insertion of iron leads to heme, while insertion of magnesium leads to chlorophyll. The Mg-chelatase from intact cucumber chloroplasts has been characterized with regard to substrate specificity, regulation, ATP requirement, and a requirement for intact chloroplasts. Mg-chelatase was isolated from maize, barley and peas and characterized in order to circumvent the intact chloroplast requirement of cucumber Mg-chelatase. Pea Mg-chelatase activity is higher than cucumber Mg-chelatase activity, and lacks the requirement for intact chloroplasts. Studies on isolated pea Mg-chelatase have shown more cofactors are required for the reaction than are seen with ferrochelatase, indicating a greater opportunity for regulatory control of this pathway. Two of the cofactors are proteins, and there appears to be a requirement for a protease-sensitive component which is outside the outer envelope. We are developing a continuous spectrophotometric assay for Mg-chelatase activity, and an assay for free heme which has shown heme efflux from intact chloroplasts. 18 refs. (MHB)

  16. Complexes and aggregates of chlorophylls

    NARCIS (Netherlands)

    Kooyman, R.P.H.

    1980-01-01

    Chlorophyll (Chl) molecules can form complexes in two important ways: by ligation at the magnesium atom and/or by hydrogen bonding at the keto- carbonyl group. Under certain conditions these processes may give rise to dimer formation. This thesis describes some properties of complexes and dimers of

  17. Isolation of chlorophyll a from spinach leaves

    Directory of Open Access Journals (Sweden)

    E.D. Dikio

    2008-08-01

    Full Text Available An efficient method for separating chlorophyll a from spinach leaves by column chromatography and solvent extraction techniques has been developed. The purity and identity of the chlorophyll a have been confirmed by UV-Vis, IR and mass spectrometry. Yields from 100 g of freeze-dried spinach were 23 – 24 mg of chlorophyll a.

  18. Relationship between chlorophyll density and SPAD chlorophyll meter reading for Jerusalem artichoke (Helianthus tuberosus L.)

    Science.gov (United States)

    Chlorophyll is an indicator of crop health and productivity. Measuring chlorophyll is usually done directly and requires significant time and resources. Indirect measurement of chlorophyll density using a handheld portable chlorophyll meter can reduce time. However, this information is very limit...

  19. The binding of quinone to the photosynthetic reaction centers: kinetics and thermodynamics of reactions occurring at the QB-site in zwitterionic and anionic liposomes.

    Science.gov (United States)

    Mavelli, Fabio; Trotta, Massimo; Ciriaco, Fulvio; Agostiano, Angela; Giotta, Livia; Italiano, Francesca; Milano, Francesco

    2014-07-01

    Liposomes represent a versatile biomimetic environment for studying the interaction between integral membrane proteins and hydrophobic ligands. In this paper, the quinone binding to the QB-site of the photosynthetic reaction centers (RC) from Rhodobacter sphaeroides has been investigated in liposomes prepared with either the zwitterionic phosphatidylcholine (PC) or the negatively charged phosphatidylglycerol (PG) to highlight the role of the different phospholipid polar heads. Quinone binding (K Q) and interquinone electron transfer (L AB) equilibrium constants in the two type of liposomes were obtained by charge recombination reaction of QB-depleted RC in the presence of increasing amounts of ubiquinone-10 over the temperature interval 6-35 °C. The kinetic of the charge recombination reactions has been fitted by numerically solving the ordinary differential equations set associated with a detailed kinetic scheme involving electron transfer reactions coupled with quinone release and uptake. The entire set of traces at each temperature was accurately fitted using the sole quinone release constants (both in a neutral and a charge separated state) as adjustable parameters. The temperature dependence of the quinone exchange rate at the QB-site was, hence, obtained. It was found that the quinone exchange regime was always fast for PC while it switched from slow to fast in PG as the temperature rose above 20 °C. A new method was introduced in this paper for the evaluation of constant K Q using the area underneath the charge recombination traces as the indicator of the amount of quinone bound to the QB-site.

  20. Control of quantum interference of an excitonic wave in a chlorophyll chain with a chlorophyll ring

    International Nuclear Information System (INIS)

    Hong, Suc-Kyoung; Nam, Seog-Woo; Yeon, Kyu-Hwang

    2010-01-01

    The quantum interference of an excitonic wave and its coherent control in a nanochain with a nanoring are studied. The nanochain is comprised of six chlorophylls, where four chlorophylls compose the nanoring and two chlorophylls are attached at two opposite sites on the nanoring. The exciton dynamics and the correlation of the excitation between chlorophylls are analyzed for a given configurational arrangement and dipolar orientation of the chlorophylls. The results of this study show that the excitation at specified chlorophylls is suppressed or enhanced by destructive or constructive interference of the excitonic wave in the chlorophyll nanochain.

  1. Modification of quinone electrochemistry by the proteins in the biological electron transfer chains: examples from photosynthetic reaction centers

    Science.gov (United States)

    Gunner, M. R.; Madeo, Jennifer; Zhu, Zhenyu

    2009-01-01

    Quinones such as ubiquinone are the lipid soluble electron and proton carriers in the membranes of mitochondria, chloroplasts and oxygenic bacteria. Quinones undergo controlled redox reactions bound to specific sites in integral membrane proteins such as the cytochrome bc1 oxidoreductase. The quinone reactions in bacterial photosynthesis are amongst the best characterized, presenting a model to understand how proteins modulate cofactor chemistry. The free energy of ubiquinone redox reactions in aqueous solution and in the QA and QB sites of the bacterial photosynthetic reaction centers (RCs) are compared. In the primary QA site ubiquinone is reduced only to the anionic semiquinone (Q•−) while in the secondary QB site the product is the doubly reduced, doubly protonated quinol (QH2). The ways in which the protein modifies the relative energy of each reduced and protonated intermediate are described. For example, the protein stabilizes Q•− while destabilizing Q= relative to aqueous solution through electrostatic interactions. In addition, kinetic and thermodynamic mechanisms for stabilizing the intermediate semiquinones are compared. Evidence for the protein sequestering anionic compounds by slowing both on and off rates as well as by binding the anion more tightly is reviewed. PMID:18979192

  2. Kinetics and mechanism of the dissociation of chlorophyll and its metalloanalogues in proton-donating media

    International Nuclear Information System (INIS)

    Berezin, B.D.; Drobysheva, A.N.; Karmanova, L.P.

    1976-01-01

    The kinetics of the dissociation of chlorophyll a and its metalloanalogues (Zn 2+ and Cd 2+ complexes of chlorophyllic acid) have been investigated in t-butyl alcohol-trichloracetic acid mixtures. The dissociation reaction is kinetically firts-order with respect to the complex. The rate constants and the activation energies and entropies for the dissociation reaction have been calculated. In order to determine the order of the reaction with respect to the protogenic species, a study was made of the ionisation of m-nitroaniline in t-butyl alcohol at 25 0 C in the trichloroacetic acid concentration range from 0.15 to 4.75 M. The dissociation reaction of chlorophyll and its zinc-containing metalloanalogue has been shown to be of second order with respect to the solvated proton. The cadmium complex dissociates by a second-order reaction with respect to trichloroacetic acid

  3. Reduction reactions of water soluble cyano-cobalt(III)-porphyrins: Metal versus ligand centered processes

    International Nuclear Information System (INIS)

    Mosseri, S.; Neta, P.; Harriman, A.; Hambright, P.

    1990-01-01

    Reduction reactions of dicyano-cobalt(III)-porphyrins [potential in vivo cyanide scavenger drugs] were studied by radiolytic and electrochemical methods using the water soluble tetrakis(4-sulfonatophenyl)porphyrin (TPPS) and tetrakis(N-methyl-4-pyridyl)porphyrin (TMPyP). For [(CN)2CoIIITPPS]-, reduction occurs stepwise to the CoII, CoI, and finally to the phlorin anion. This behavior is similar to that of the cobalt porphyrins in the absence of cyanide, except that the cyanide ligand shifts the reduction potentials to much more negative values. On the other hand, under radiolytic conditions, [(CN)2CoIIITMPyP]- is reduced on the porphyrin macrocycle by one electron to give the CoIII pi-radical anion, which disproportionates into the initial complex and the two-electron ring reduced CoIII phlorin. The radical anion is also formed by intramolecular electron transfer subsequent to the reaction of CoIITMPyP and cyanide. The results are compared with the chemistry of Vitamin B-12

  4. Chlorophyll as a measure of plant health: Agroecological aspects

    Directory of Open Access Journals (Sweden)

    Danijela Pavlović

    2014-03-01

    Full Text Available As photosynthesis is the basic process during which light energy is absorbed and converted into organic matter, the importance of the plant pigment chlorophyll (a and b forms as an intermediary in transformation of the absorbed solar energy and its activity in the process of photosynthesis and synthesis of organic substances in plants are crucial. Therefore, this paper provides an overview of methods for monitoring the optical activity of chlorophyll molecules and methods (non-destructive and destructive for quantification of chlorophyll in plants. These methods are used to estimate the effects of different stress factors (abiotic, biotic and xenobiotic on the efficiency of photosynthesis and bioproductivity, aiming to assess the impact that these limiting factors have on the yield of various cultivars. Also, those methods for analysis of chlorophyll optical activity and/or content are appropriate for assessing the reaction of weed species to different agricultural practices (mineral nutrition, treatment by herbicides, etc. and studies of different aspects of weed ecophysiology and their influence on crop harvest.

  5. Density functional theoretical study on the C-F and C-O oxidative addition reaction at an AI center

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yong Seong [Dept. of Science Education, Kyungnam University, Masan (Korea, Republic of); Cho, Hyun; Hwang, Sungu [Dept. of Nanomechatronics Engineering, Pusan National University, Miryang (Korea, Republic of)

    2017-02-15

    In this study, B3LYP/LACVP** level calculations were chosen because the level of theory was applied successfully to calculations of the thermodynamic and kinetic features of the oxidative addition reactions of alkyl and aryl halides to pincer-type complexes. This study examined the effects of the substituents on the phenyl rings of the Al(I) center. Isopropyl side chains in the phenyl rings attached to N atoms of the pincer ligand were replaced with a methyl (Me) (2) or tertiary butyl ( t Bu) group. The oxidative addition of C[BOND]F and C[BOND]O bonds to an Al (I) center was investigated computationally by DFT calculations. The geometries, thermodynamic, and kinetic features were in good agreement with the experimental data, as in previous studies on the transition metal complexes. The computational results showed that the DFT calculations could provide qualitative insight into the reactivity and thermodynamics of the oxidative addition reactions of C[BOND]F bonds.

  6. Stereoselective synthesis of organosulfur compounds incorporating N-aromatic heterocyclic motifs and quaternary carbon centers via a sulfa-Michael triggered tandem reaction.

    Science.gov (United States)

    Qin, Tianyou; Cheng, Lu; Zhang, Sean Xiao-An; Liao, Weiwei

    2015-06-14

    A novel sulfa-Michael addition (SMA)-triggered tandem reaction was developed by combining a SMA reaction with a simultaneous rearomatization process utilizing a less reactive carbonyl group as an intramolecular electrophile partner, which provided a unique synthetic route to access various organosulfur compounds incorporating an N-aromatic heterocyclic motif and quaternary carbon centers.

  7. High-pressure modulation of the structure of the bacterial photochemical reaction center at physiological and cryogenic temperatures

    Science.gov (United States)

    Timpmann, Kõu; Kangur, Liina; Lõhmus, Ants; Freiberg, Arvi

    2017-07-01

    The optical absorption and fluorescence response to external high pressure of the reaction center membrane chromoprotein complex from the wild-type non-sulfur photosynthetic bacterium Rhodobacter sphaeroides was investigated using the native pigment cofactors as local molecular probes of the reaction center structure at physiological (ambient) and cryogenic (79 K) temperatures. In detergent-purified complexes at ambient temperature, abrupt blue shift and accompanied broadening of the special pair band was observed at about 265 MPa. These reversible in pressure features were assigned to a pressure-induced rupture of a lone hydrogen bond that binds the photo-chemically active L-branch primary electron donor bacteriochlorophyll cofactor to the surrounding protein scaffold. In native membrane-protected complexes the hydrogen bond rupture appeared significantly restricted and occurred close to about 500 MPa. The free energy change associated with the rupture of the special pair hydrogen bond in isolate complexes was estimated to be equal to about 12 kJ mol-1. In frozen samples at cryogenic temperatures the hydrogen bond remained apparently intact up to the maximum utilized pressure of 600 MPa. In this case, however, heterogeneous spectral response of the cofactors from the L-and M-branches was observed due to anisotropic build-up of the protein structure. While in solid phase, the special pair fluorescence as a function of pressure exactly followed the respective absorption spectrum at a constant Stokes shift, at ambient temperature, the two paths began to deviate strongly from one other at the hydrogen bond rupture pressure. This effect was tentatively interpreted by different emission properties of hydrogen-bound and hydrogen-unbound special pair exciton states.

  8. Comments on the optical lineshape function: Application to transient hole-burned spectra of bacterial reaction centers

    International Nuclear Information System (INIS)

    Reppert, Mike; Kell, Adam; Pruitt, Thomas; Jankowiak, Ryszard

    2015-01-01

    The vibrational spectral density is an important physical parameter needed to describe both linear and non-linear spectra of multi-chromophore systems such as photosynthetic complexes. Low-temperature techniques such as hole burning (HB) and fluorescence line narrowing are commonly used to extract the spectral density for a given electronic transition from experimental data. We report here that the lineshape function formula reported by Hayes et al. [J. Phys. Chem. 98, 7337 (1994)] in the mean-phonon approximation and frequently applied to analyzing HB data contains inconsistencies in notation, leading to essentially incorrect expressions in cases of moderate and strong electron-phonon (el-ph) coupling strengths. A corrected lineshape function L(ω) is given that retains the computational and intuitive advantages of the expression of Hayes et al. [J. Phys. Chem. 98, 7337 (1994)]. Although the corrected lineshape function could be used in modeling studies of various optical spectra, we suggest that it is better to calculate the lineshape function numerically, without introducing the mean-phonon approximation. New theoretical fits of the P870 and P960 absorption bands and frequency-dependent resonant HB spectra of Rb. sphaeroides and Rps. viridis reaction centers are provided as examples to demonstrate the importance of correct lineshape expressions. Comparison with the previously determined el-ph coupling parameters [Johnson et al., J. Phys. Chem. 94, 5849 (1990); Lyle et al., ibid. 97, 6924 (1993); Reddy et al., ibid. 97, 6934 (1993)] is also provided. The new fits lead to modified el-ph coupling strengths and different frequencies of the special pair marker mode, ω sp , for Rb. sphaeroides that could be used in the future for more advanced calculations of absorption and HB spectra obtained for various bacterial reaction centers

  9. Comments on the optical lineshape function: Application to transient hole-burned spectra of bacterial reaction centers

    Energy Technology Data Exchange (ETDEWEB)

    Reppert, Mike; Kell, Adam; Pruitt, Thomas [Department of Chemistry, Kansas State University, Manhattan, Kansas 66506 (United States); Jankowiak, Ryszard, E-mail: ryszard@ksu.edu [Department of Chemistry, Kansas State University, Manhattan, Kansas 66506 (United States); Department of Physics, Kansas State University, Manhattan, Kansas 66506 (United States)

    2015-03-07

    The vibrational spectral density is an important physical parameter needed to describe both linear and non-linear spectra of multi-chromophore systems such as photosynthetic complexes. Low-temperature techniques such as hole burning (HB) and fluorescence line narrowing are commonly used to extract the spectral density for a given electronic transition from experimental data. We report here that the lineshape function formula reported by Hayes et al. [J. Phys. Chem. 98, 7337 (1994)] in the mean-phonon approximation and frequently applied to analyzing HB data contains inconsistencies in notation, leading to essentially incorrect expressions in cases of moderate and strong electron-phonon (el-ph) coupling strengths. A corrected lineshape function L(ω) is given that retains the computational and intuitive advantages of the expression of Hayes et al. [J. Phys. Chem. 98, 7337 (1994)]. Although the corrected lineshape function could be used in modeling studies of various optical spectra, we suggest that it is better to calculate the lineshape function numerically, without introducing the mean-phonon approximation. New theoretical fits of the P870 and P960 absorption bands and frequency-dependent resonant HB spectra of Rb. sphaeroides and Rps. viridis reaction centers are provided as examples to demonstrate the importance of correct lineshape expressions. Comparison with the previously determined el-ph coupling parameters [Johnson et al., J. Phys. Chem. 94, 5849 (1990); Lyle et al., ibid. 97, 6924 (1993); Reddy et al., ibid. 97, 6934 (1993)] is also provided. The new fits lead to modified el-ph coupling strengths and different frequencies of the special pair marker mode, ω{sub sp}, for Rb. sphaeroides that could be used in the future for more advanced calculations of absorption and HB spectra obtained for various bacterial reaction centers.

  10. Evaluation of water quality by chlorophyll and dissolved oxygen

    International Nuclear Information System (INIS)

    Latif, Z.; Tasneem, M.A.; Javed, T.; Butt, S.; Fazil, M.; Ali, M.; Sajjad, M.I.

    2002-01-01

    This paper focuses on the impact of Chlorophyll and dissolved Oxygen on water quality. Kalar Kahar and Rawal lakes were selected for this research. A Spectrophotometer was used for determination of Chlorophyll a, Chlorophyll b, Chlorophyll c and Pheophytin pigment. Dissolved Oxygen was measured in situ, using dissolved oxygen meter. The gamma O/sup 18/ of dissolved Oxygen, like concentration, is affected primarily by three processes: air water gas exchange, respiration and photosynthesis; gamma O/sup 18/ is analyzed on isotopic ratio mass spectrometer, after extraction of dissolved Oxygen from water samples, followed by purification and conversion into CO/sub 2/. Rawal lake receives most of the water from precipitation during monsoon period and supplemented by light rains in December and January. This water is used throughout the year for drinking purposes in Rawalpindi city. The water samples were collected from 5, 7.5, and 10 meters of depth for seasonal studies of physiochemical and isotopic parameters of water and dissolved Oxygen. Optimum experimental conditions for delta O/sup 18/ analysis of dissolved Oxygen from aqueous samples were determined. Stratification of dissolved Oxygen was observed in Rawal Lake before rainy season in summer. The water quality deteriorates with depth, because the respiration exceeds the photosynthesis and gas exchange. The concentration and delta O/sup 18/ of dissolved Oxygen show no variation with depth in 1998 winter sampling. Kalar Kahar lake gets water from springs, which are recharged by local rains on the nearby mountains. It is a big lake, with shallow and uniform depth of nearly 1.5 meters. A lot of vegetation can be seen on the periphery of the lake. Algae have grown on the floor of the lake Water samples were collected from the corner with large amount of vegetation and from the center of the lake for dissolved Oxygen and Chlorophyll measurements. Chlorophyll result shows that Kalar Kahar Lake falls in Eutrophic category

  11. Qtl mapping of wheat doubled haploids for chlorophyll content and chlorophyll fluorescence kinetics under drought stress imposed at anthesis stage

    International Nuclear Information System (INIS)

    Ilyas, M.; Ilyas, N.; Arshad, M.; Kazi, A.G.

    2014-01-01

    Drought stress is one of the major environmental constraints to crop plants including wheat worldwide. Synthetic hexaploid can act as a vehicle for improving crop tolerance against biotic and abiotic stresses. Doubled haploid population consisting of one hundred and forty individuals derived from cross of Opata and SH223 was used in the present study to identify genomic regions associated with various quantitative attributes of physiological nature. Doubled haploid mapping population was phenotyped for chlorophyll content and chlorophyll fluorescence kinetics under control and drought stress imposed at anthesis stage. Genotyping of population was accomplished by utilizing two hundred and sixty one polymorphic Gaterslaben wheat microsatellites and Beltsville agriculture research center simple sequence repeats. Linkage map of doubled haploid population comprising of 19 linkage groups and covering map length of two thousands six hundred and twenty six (2626) cM was constructed using map maker software. Major and minor QTLs associated with quantitative traits were identified using QGene software. Major QTL for chlorophyll content (QTc.wwc-1B-S11) of doubled haploid mapping population under anthesis drought stress was mapped on chromosome 1B and explained 10.09 percent of phenotypic variation at LOD score of 5.5. Seven major and minor QTLs for PCFK of doubled haploids were identified on chromosome 1B, 7A and 7D under control and drought stress at anthesis stage. The identified QTLs are of prime importance for high resolution mapping in synthetic hexaploid wheat. Genomic synteny of doubled haploids was observed with rice chromosome 2, 4, 7 and maize chromosome 7 owing to occurrence of orthologous QTLs for chlorophyll content and chlorophyll fluorescence respectively. (author)

  12. Distribution of nutrients, chlorophyll and phytoplankton primary ...

    African Journals Online (AJOL)

    Distribution of nutrients, chlorophyll and phytoplankton primary production in ... Two cruises were undertaken in the vicinity of the Cape Frio upwelling cell ... and concentrations of nitrate, phosphate, silicate, oxygen and chlorophyll a. ... Estimates of the annual primary production for each of the water bodies were calculated.

  13. Quantifying mangrove chlorophyll from high spatial resolution imagery

    NARCIS (Netherlands)

    Heenkenda, M.K.; Joyce, K.E.; Maier, S.W.; Bruin, de S.

    2015-01-01

    Lower than expected chlorophyll concentration of a plant can directly limit photosynthetic activity, and resultant primary production. Low chlorophyll concentration may also indicate plant physiological stress. Compared to other terrestrial vegetation, mangrove chlorophyll variations are poorly

  14. The evolutionary pathway from anoxygenic to oxygenic photosynthesis examined by comparison of the properties of photosystem II and bacterial reaction centers.

    Science.gov (United States)

    Allen, J P; Williams, J C

    2011-01-01

    In photosynthetic organisms, such as purple bacteria, cyanobacteria, and plants, light is captured and converted into energy to create energy-rich compounds. The primary process of energy conversion involves the transfer of electrons from an excited donor molecule to a series of electron acceptors in pigment-protein complexes. Two of these complexes, the bacterial reaction center and photosystem II, are evolutionarily related and structurally similar. However, only photosystem II is capable of performing the unique reaction of water oxidation. An understanding of the evolutionary process that lead to the development of oxygenic photosynthesis can be found by comparison of these two complexes. In this review, we summarize how insight is being gained by examination of the differences in critical functional properties of these complexes and by experimental efforts to alter pigment-protein interactions of the bacterial reaction center in order to enable it to perform reactions, such as amino acid and metal oxidation, observable in photosystem II.

  15. BOREAS TE-9 NSA Leaf Chlorophyll Density

    Science.gov (United States)

    Hall, Forrest G. (Editor); Curd, Shelaine (Editor); Margolis, Hank; Sy, Mikailou

    2000-01-01

    The BOREAS TE-9 team collected several data sets related to chemical and photosynthetic properties of leaves in boreal forest tree species. These data were collected to help provide an explanation of potential seasonal and spatial changes of leaf pigment properties in boreal forest species at the NSA. At different dates (FFC-Winter, FFC-Thaw, IFC-1, IFC-2, and IMC-3), foliage samples were collected from the upper third of the canopy for five NSA sites (YJP, OJP, OBS, UBS, and OA) near Thompson, Manitoba. Subsamples of 100 needles for black spruce, 20 needles for jack pine, and single leaf for trembling aspen were cut into pieces and immersed in a 20-mL DMF aliquot in a Nalgene test tube. The extracted foliage materials were then oven-dried at 68 C for 48 hours and weighed. Extracted leaf dry weight was converted to a total leaf area basis to express the chlorophyll content in mg/sq cm of total leaf area. The data are provided in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

  16. Electron transfer. 93. Further reactions of transition-metal-center oxidants with vitamin B12s (Cob(I)alamin)

    International Nuclear Information System (INIS)

    Pillai, G.C.; Ghosh, S.K.; Gould, E.S.

    1988-01-01

    Vitamin B 12s (cob(I)alamin) reduces europium(III), titanium(IV) (TiO(C 2 O 4 ) 2 2- ), and uranium(VI) in aqueous solution. These oxidants undergo one-electron changes, leading in each case to the cobalt product cob(II)alamin (B 12r ). The reduction of Eu 3+ , which is inhibited by TES buffer, but not by glycine, is outer sphere. Its limiting specific rate (1 x 10 2 M -1 s -1 ), incorporated in the Marcus treatment, yields a B 12s ,B 12r self-exchange rate of 10 4.8±0.5 M -1 s -1 . Reductions of TiO(C 2 O 4 ) 2 2- are accelerated by H + and by acetic acid. Kinetic patterns suggest three competing reaction paths involving varying degrees of protonation of the Ti(IV) center or its association with acetic acid. The very rapid reduction of U(VI) (k = 4 x 10 6 M -1 s -1 ) yields U(V) in several buffering media, even when B 12s is taken in excess. The much slower conversion of U(V) to U(IV), although thermodynamically favored, appears to be retarded by the extensive reorganization of the coordination sphere of oxo-bound U(V) that must accompany its acceptance of an additional electron. The observed specific rate for the B 12s -U(VI) reaction is in reasonable agreement, in the framework of the Marcus formalism, with reported values of the formal potential and the self-exchange rate for U(V,VI). 37 references, 4 tables

  17. B-side charge separation in bacterial photosynthetic reaction centers: nanosecond time scale electron transfer from HB- to QB.

    Science.gov (United States)

    Kirmaier, Christine; Laible, Philip D; Hanson, Deborah K; Holten, Dewey

    2003-02-25

    We report time-resolved optical measurements of the primary electron transfer reactions in Rhodobacter capsulatus reaction centers (RCs) having four mutations: Phe(L181) --> Tyr, Tyr(M208) --> Phe, Leu(M212) --> His, and Trp(M250) --> Val (denoted YFHV). Following direct excitation of the bacteriochlorophyll dimer (P) to its lowest excited singlet state P, electron transfer to the B-side bacteriopheophytin (H(B)) gives P(+)H(B)(-) in approximately 30% yield. When the secondary quinone (Q(B)) site is fully occupied, P(+)H(B)(-) decays with a time constant estimated to be in the range of 1.5-3 ns. In the presence of excess terbutryn, a competitive inhibitor of Q(B) binding, the observed lifetime of P(+)H(B)(-) is noticeably longer and is estimated to be in the range of 4-8 ns. On the basis of these values, the rate constant for P(+)H(B)(-) --> P(+)Q(B)(-) electron transfer is calculated to be between approximately (2 ns)(-)(1) and approximately (12 ns)(-)(1), making it at least an order of magnitude smaller than the rate constant of approximately (200 ps)(-)(1) for electron transfer between the corresponding A-side cofactors (P(+)H(A)(-) --> P(+)Q(A)(-)). Structural and energetic factors associated with electron transfer to Q(B) compared to Q(A) are discussed. Comparison of the P(+)H(B)(-) lifetimes in the presence and absence of terbutryn indicates that the ultimate (i.e., quantum) yield of P(+)Q(B)(-) formation relative to P is 10-25% in the YFHV RC.

  18. Electronically stimulated deep-center reactions in electron-irradiated InP: Comparison between experiment and recombination-enhancement theories

    International Nuclear Information System (INIS)

    Sibille, A.

    1987-01-01

    We present a detailed study of the recombination enhancement of several defect reactions involving the main deep centers in low-temperature electron-irradiated InP. A fairly good agreement is obtained with the Weeks-Tully-Kimerling theory for the activation energies of the enhanced process. On the other hand, a thorough investigation of a thermally and electronically stimulated defect transformation shows evidence that one major approximation (local vibrational equilibrium) fails, and that the recently proposed [H. Sumi, Phys. Rev. B 29, 4616 (1984)] mechanism of coherent recombination on deep centers is responsible for altered reaction rates at high injection levels

  19. Menaquinone-7 in the reaction center complex of the green sulfur bacterium Chlorobium vibrioforme functions as the electron acceptor A1

    DEFF Research Database (Denmark)

    Kjaer, B; Frigaard, N-U; Yang, F

    1998-01-01

    Photosynthetically active reaction center complexes were prepared from the green sulfur bacterium Chlorobium vibrioforme NCIMB 8327, and the content of quinones was determined by extraction and high-performance liquid chromatography. The analysis showed a stoichiometry of 1.7 molecules of menaqui......Photosynthetically active reaction center complexes were prepared from the green sulfur bacterium Chlorobium vibrioforme NCIMB 8327, and the content of quinones was determined by extraction and high-performance liquid chromatography. The analysis showed a stoichiometry of 1.7 molecules...

  20. Radiation induced chlorophyll mutations in rice

    International Nuclear Information System (INIS)

    Bari, G.; Mustafa, G.; Soomro, A.M.; Baloch, A.W.

    1985-01-01

    Air dried grains of four local varieties of rice were treated with gamma-rays and fast neutrons for determining their mutagenic effectiveness through the occurence of chlorophyll mutations. Fast neutrons were more effective in inducing chlorophyll mutations and the rice variety Basmati 370 produced maximum number of mutations followed by varieties Sonahri Sugdasi, Jajai 77 and Sada Gulab. The highest frequency of chlorophyll mutations was that of albina types followed by striata types. The xantha, viridis and tigrina types of mutations were less frequent. (authors)

  1. Equilibration kinetics in isolated and membrane-bound photosynthetic reaction centers upon illumination: a method to determine the photoexcitation rate.

    Science.gov (United States)

    Manzo, Anthony J; Goushcha, Alexander O; Barabash, Yuri M; Kharkyanen, Valery N; Scott, Gary W

    2009-07-01

    Kinetics of electron transfer, following variation of actinic light intensity, for photosynthetic reaction centers (RCs) of purple bacteria (isolated and membrane-bound) were analyzed by measuring absorbance changes in the primary photoelectron donor absorption band at 865 nm. The bleaching of the primary photoelectron donor absorption band in RCs, following a sudden increase of illumination from the dark to an actinic light intensity of I(exp), obeys a simple exponential law with the rate constant alphaI(exp) + k(rec), in which alpha is a parameter relating the light intensity, measured in mW/cm(2), to a corresponding theoretical rate in units of reciprocal seconds, and k(rec) is the effective rate constant of the charge recombination in the photosynthetic RCs. In this work, a method for determining the alpha parameter value is developed and experimentally verified for isolated and membrane-bound RCs, allowing for rigorous modeling of RC macromolecule dynamics under varied photoexcitation conditions. Such modeling is necessary for RCs due to alterations of the forward photoexcitation rates and relaxation rates caused by illumination history and intramolecular structural dynamics effects. It is demonstrated that the classical Bouguer-Lambert-Beer formalism can be applied for the samples with relatively low scattering, which is not necessarily the case with strongly scattering media or high light intensity excitation.

  2. Reaction Control System Thruster Cracking Consultation: NASA Engineering and Safety Center (NESC) Materials Super Problem Resolution Team (SPRT) Findings

    Science.gov (United States)

    MacKay, Rebecca A.; Smith, Stephen W.; Shah, Sandeep R.; Piascik, Robert S.

    2005-01-01

    The shuttle orbiter s reaction control system (RCS) primary thruster serial number 120 was found to contain cracks in the counter bores and relief radius after a chamber repair and rejuvenation was performed in April 2004. Relief radius cracking had been observed in the 1970s and 1980s in seven thrusters prior to flight; however, counter bore cracking had never been seen previously in RCS thrusters. Members of the Materials Super Problem Resolution Team (SPRT) of the NASA Engineering and Safety Center (NESC) conducted a detailed review of the relevant literature and of the documentation from the previous RCS thruster failure analyses. It was concluded that the previous failure analyses lacked sufficient documentation to support the conclusions that stress corrosion cracking or hot-salt cracking was the root cause of the thruster cracking and lacked reliable inspection controls to prevent cracked thrusters from entering the fleet. The NESC team identified and performed new materials characterization and mechanical tests. It was determined that the thruster intergranular cracking was due to hydrogen embrittlement and that the cracking was produced during manufacturing as a result of processing the thrusters with fluoride-containing acids. Testing and characterization demonstrated that appreciable environmental crack propagation does not occur after manufacturing.

  3. Development of the spectrometric imaging apparatus of laser induced fluorescence from plants and estimation of chlorophyll contents of rice leaves; Laser reiki keiko sokutei sochi no kaihatsu to inehanai no chlorophyll ganryo no suitei

    Energy Technology Data Exchange (ETDEWEB)

    Nakaya, K.; Shoji, K.; Hanyu, H.

    1999-05-01

    Photosynthetic activity of plants is an important factor to assess the micrometeorological effect of plant canopy or to estimate the influence of circumstances such as water stress. Light illumination induces fluorescence from a leaf or suspension of chloroplasts. The red chlorophyll fluorescence had been used to determine the process of the electron transportation in photosynthetic reaction. The fluorescence source other than chlorophyll is not announced sufficiently, but is supposed to be useful to determine the contents of the substance corresponding to physiological response of plants. We developed a fluorescence imaging apparatus to observe spectrum and distribution of laser induced fluorescence from a leaf. Pulsed UV-laser (Nd:YAG) induced blue-green fluorescence and red chlorophyll fluorescence from a green leaf. The pulse modulated measuring light and CCD with image-intensifier (ICCD) enable to detect the fluorescence from plants under illumination. The laser induced fluorescence (LIF) spectra were investigated to estimate the chlorophyll contents in leaves of rice. During the greening course of dark grown etiolated rice leaves, chlorophyll contents were determined using the extraction of leaves and steady state LIF spectra were measured. As a result, the ratio of fluorescent intensity between blue-green and red peaks (F460/F740 and F510/F740) decreased in proportion to alteration of chlorophyll contents respectively. These fluorescence intensity ratios perform more precise estimation of higher chlorophyll contents of leaves than reported red chlorophyll fluorescence intensity ratio (F690/E740). (author)

  4. Energetic change of the primary quinone in photosynthetic reaction center. Mutation, delayed fluorescence and model calculations (Theses of the Ph.D. dissertation)

    International Nuclear Information System (INIS)

    Rinyu, L.

    2007-01-01

    Complete text of publication follows. Photosynthesis is one of the basic metabolic processes of living organisms. Photosynthesizing species (bacteria, algae and higher class plants) convert the energy of light into other forms of free energy (redox potential, electro- chemical potential of ions and protons and phosphate-potential) which are directly suit- able either to cover the energy need of the vital processes of the cell or to storage. In reaction center (RC) protein of photo- synthetic bacteria, electron transfer is initiated upon light excitation from the excited bacteriochlorophyll dimer (P) to the secondary quinone (Q B ) via bacteriopheophytine (Bph) and the primary quinone (Q A ). In Rhodobacter sphaeroides purple bacteria, both quinones are ubiquinone-10, but due to the different protein environment, their electrochemical properties is highly different. Whereas Q A makes one-electron chemistry, Q B can be doubly reduced to form hydroquinone, Q B H 2 by uptake of two protons. Q B H 2 subsequently leaves the RC and is replaced by an oxidized quinone from to membrane pool. The semiquinones are important intermediates in the quinone reduction cycle of the RC. The redox midpoint potentials of the Q/Q - redox pairs (E m ) are also different: the Q A /Q A - has 60 mV more negative potential than the Q B /Q B - couple (pH 8) to make the (interquinone) electron transfer favorable. For fine tuning of the midpoint redox potentials of the quinones, the protein assures appropriate steric and electrostatic environment. The most important aim of this study was the design and production of reaction center mutants in the binding pocket of the primary quinone to investigate the effect of the amino acids of the protein and lipids of the membrane on the thermodynamics of the primary quinone. The first priority was the determination of the absolute free energy gap between the P* and the P + Q A - states in wild type and mutant reaction centers by comparison of the

  5. Seasonal Composite Chlorophyll Concentrations - Gulf of Maine

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This personal geodatabase contains raster images of chlorophyll concentrations in the Gulf of Maine. These raster images are seasonal composites, and were calculated...

  6. EmpiricalValues_Chlorophyll_GrandComposite

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This personal geodatabase contains raster images of chlorophyll concentrations in the Gulf of Maine. These raster images are a composite of several years (1997-2005)...

  7. Monthly Composite Chlorophyll Concentrations - Gulf of Maine

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This personal geodatabase contains raster images of chlorophyll concentrations in the Gulf of Maine. These raster images are monthly composites, and were calculated...

  8. Hydrogen bonds in the vicinity of the special pair of the bacterial reaction center probed by hydrostatic high-pressure absorption spectroscopy.

    Science.gov (United States)

    Kangur, Liina; Jones, Michael R; Freiberg, Arvi

    2017-12-01

    Using the native bacteriochlorophyll a pigment cofactors as local probes, we investigated the response to external hydrostatic high pressure of reaction center membrane protein complexes from the photosynthetic bacterium Rhodobacter sphaeroides. Wild-type and engineered complexes were used with a varied number (0, 1 or 2) of hydrogen bonds that bind the reaction center primary donor bacteriochlorophyll cofactors to the surrounding protein scaffold. A pressure-induced breakage of hydrogen bonds was established for both detergent-purified and membrane-embedded reaction centers, but at rather different pressures: between 0.2 and 0.3GPa and at about 0.55GPa, respectively. The free energy change associated with the rupture of the single hydrogen bond present in wild-type reaction centers was estimated to be equal to 13-14kJ/mol. In the mutant with two symmetrical hydrogen bonds (FM197H) a single cooperative rupture of the two bonds was observed corresponding to an about twice stronger bond, rather than a sequential rupture of two individual bonds. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Notable light-free catalytic activity for pollutant destruction over flower-like BiOI microspheres by a dual-reaction-center Fenton-like process.

    Science.gov (United States)

    Wang, Liang; Yan, Dengbiao; Lyu, Lai; Hu, Chun; Jiang, Ning; Zhang, Lili

    2018-10-01

    BiOI is widely used as photocatalysts for pollutant removal, water splitting, CO 2 reduction and organic transformation due to its excellent photoelectric properties. Here, we report for the first time that a light-free catalyst consisting of the flower-like BiOI microspheres (f-BiOI MSs) exposing (1 0 1) and (1 1 0) crystal planes prepared by a hydrothermal method in ethylene glycol environment can rapidly eliminate the refractory BPA within only ∼3 min through a Fenton-like process. The reaction activity is ∼190 times higher than that of the conventional Fenton catalyst Fe 2 O 3 . A series of characterizations and experiments reveal the formation of the dual reaction centers on f-BiOI MSs. The electron-rich O centers efficiently reduce H 2 O 2 to OH, while the electron-poor oxygen vacancies capture electrons from the adsorbed pollutants and divert them to the electron-rich area during the Fenton-like reactions. By these processes, pollutants are degraded and mineralized quickly in a wide pH range. Our findings address the problems of the classical Fenton reaction and are useful for the development of efficient Fenton-like catalysts through constructing dual reaction centers. Copyright © 2018 Elsevier Inc. All rights reserved.

  10. Induction of chlorophyll chimeras and chlorophyll mutations in mungbean (Vigna radiata) cv. T44

    International Nuclear Information System (INIS)

    Singh, V.P.; Yadav, R.D.S.

    1993-01-01

    Uniform and healthy seeds of mungbean (Vigna radiata) cv. T44 were exposed to varying doses of gamma rays, ethyl methane sulphonate (EMS) and combination treatment of gamma rays with EMS. The data were recorded for seed germination, plant survival, frequency and spectrum of chlorophyll chimeras in M 1 and chlorophyll mutations in M 2 generation. Among all, the combination treatments were found most effective for inducing chlorophyll chimeras and chlorophyll mutations than the gamma rays or EMS alone. Of the mutants under reference, the albino, xantha and chlorina showed monogenic recessive while viridis exhibited digenic recessive inheritance. (author). 8 refs., 2 tabs

  11. Synthesis of chlorophyll b: Localization of chlorophyllide a oxygenase and discovery of a stable radical in the catalytic subunit

    Science.gov (United States)

    Eggink, Laura L; LoBrutto, Russell; Brune, Daniel C; Brusslan, Judy; Yamasato, Akihiro; Tanaka, Ayumi; Hoober, J Kenneth

    2004-01-01

    Background Assembly of stable light-harvesting complexes (LHCs) in the chloroplast of green algae and plants requires synthesis of chlorophyll (Chl) b, a reaction that involves oxygenation of the 7-methyl group of Chl a to a formyl group. This reaction uses molecular oxygen and is catalyzed by chlorophyllide a oxygenase (CAO). The amino acid sequence of CAO predicts mononuclear iron and Rieske iron-sulfur centers in the protein. The mechanism of synthesis of Chl b and localization of this reaction in the chloroplast are essential steps toward understanding LHC assembly. Results Fluorescence of a CAO-GFP fusion protein, transiently expressed in young pea leaves, was found at the periphery of mature chloroplasts and on thylakoid membranes by confocal fluorescence microscopy. However, when membranes from partially degreened cells of Chlamydomonas reinhardtii cw15 were resolved on sucrose gradients, full-length CAO was detected by immunoblot analysis only on the chloroplast envelope inner membrane. The electron paramagnetic resonance spectrum of CAO included a resonance at g = 4.3, assigned to the predicted mononuclear iron center. Instead of a spectrum of the predicted Rieske iron-sulfur center, a nearly symmetrical, approximately 100 Gauss peak-to-trough signal was observed at g = 2.057, with a sensitivity to temperature characteristic of an iron-sulfur center. A remarkably stable radical in the protein was revealed by an isotropic, 9 Gauss peak-to-trough signal at g = 2.0042. Fragmentation of the protein after incorporation of 125I- identified a conserved tyrosine residue (Tyr-422 in Chlamydomonas and Tyr-518 in Arabidopsis) as the radical species. The radical was quenched by chlorophyll a, an indication that it may be involved in the enzymatic reaction. Conclusion CAO was found on the chloroplast envelope and thylakoid membranes in mature chloroplasts but only on the envelope inner membrane in dark-grown C. reinhardtii cells. Such localization provides further

  12. Reactive scattering from oriented molecules: The three-center reaction K+ICl --> KI+Cl, KCl+I

    Science.gov (United States)

    Loesch, H. J.; Möller, J.

    1992-12-01

    In a crossed molecular beam experiment, we have measured the angular and time-of-flight (TOF) distributions of the products KCl and KI formed in the reaction K+ICl→KI+Cl, KCl+I at an elevated collision energy of Etr=1.64 eV. Employing the brute force method, we have prepared an oriented ICl beam and studied in addition also the orientation dependence of these distributions. The results are (i) KCl is the dominant product, but also KI is substantially formed with a branching ratio of 4:1; (ii) the double differential reaction cross section in the center-of-mass frame (contour maps) indicates that all products are preferentially forward scattered and constrained to the forward hemisphere; (iii) the KCl flux consists of two distinct components which differ markedly in kinetic energy and dependence on the ICl orientation; there are also indications of the existence of two components of KI; (iv) 65%, 84%, and 64% of the available energy is vested into the internal degrees of freedom for the fast, slow component of KCl and KI, respectively; (v) the existence of two components can be rationalized on the basis of the harpooning mechanism where the jumping electron accesses the ground state or one of the low excited states of the ICl- ion and triggers the subsequent explosion of the ion with more or less kinetic energy of the fragments depending on the initially populated state; (vi) the energies released during dissociation of ICl- in the 2Σ ground state and the first 2Π state are ≤0.19 and ≤1.2 eV, respectively; (vii) the fast KCl component features a negative steric effect suggesting favorable product formation for attacks of K to the I end of ICl, the steric effect of the slow KI component is positive, i.e., attacks to the Cl end form products favorably; the other components exhibit no significant steric effect; (viii) the steric effects can be quantitatively rationalized using the same model as mentioned above; (ix) the magnitude of the steric effect suggests a

  13. Mediterranean Ocean Colour Chlorophyll Trends.

    Science.gov (United States)

    Colella, Simone; Falcini, Federico; Rinaldi, Eleonora; Sammartino, Michela; Santoleri, Rosalia

    2016-01-01

    In being at the base of the marine food web, phytoplankton is particularly important for marine ecosystem functioning (e.g., biodiversity). Strong anthropization, over-exploitation of natural resources, and climate change affect the natural amount of phytoplankton and, therefore, represent a continuous threat to the biodiversity in marine waters. In particular, a concerning risks for coastal waters is the increase in nutrient inputs of terrestrial/anthropogenic origin that can lead to undesirable modifications of phytoplankton concentration (i.e., eutrophication). Monitoring chlorophyll (Chl) concentration, which is a proxy of phytoplankton biomass, is an efficient tool for recording and understanding the response of the marine ecosystem to human pressures and thus for detecting eutrophication. Here, we compute Chl trends over the Mediterranean Sea by using satellite data, also highlighting the fact that remote sensing may represent an efficient and reliable solution to synoptically control the "good environmental status" (i.e., the Marine Directive to achieve Good Environmental Status of EU marine waters by 2020) and to assess the application of international regulations and environmental directives. Our methodology includes the use of an ad hoc regional (i.e., Mediterranean) algorithm for Chl concentration retrieval, also accounting for the difference between offshore (i.e., Case I) and coastal (i.e., Case II) waters. We apply the Mann-Kendall test and the Sens's method for trend estimation to the Chl concentration de-seasonalized monthly time series, as obtained from the X-11 technique. We also provide a preliminary analysis of some particular trends by evaluating their associated inter-annual variability. The high spatial resolution of our approach allows a clear identification of intense trends in those coastal waters that are affected by river outflows. We do not attempt to attribute the observed trends to specific anthropogenic events. However, the trends

  14. Mediterranean Ocean Colour Chlorophyll Trends.

    Directory of Open Access Journals (Sweden)

    Simone Colella

    Full Text Available In being at the base of the marine food web, phytoplankton is particularly important for marine ecosystem functioning (e.g., biodiversity. Strong anthropization, over-exploitation of natural resources, and climate change affect the natural amount of phytoplankton and, therefore, represent a continuous threat to the biodiversity in marine waters. In particular, a concerning risks for coastal waters is the increase in nutrient inputs of terrestrial/anthropogenic origin that can lead to undesirable modifications of phytoplankton concentration (i.e., eutrophication. Monitoring chlorophyll (Chl concentration, which is a proxy of phytoplankton biomass, is an efficient tool for recording and understanding the response of the marine ecosystem to human pressures and thus for detecting eutrophication. Here, we compute Chl trends over the Mediterranean Sea by using satellite data, also highlighting the fact that remote sensing may represent an efficient and reliable solution to synoptically control the "good environmental status" (i.e., the Marine Directive to achieve Good Environmental Status of EU marine waters by 2020 and to assess the application of international regulations and environmental directives. Our methodology includes the use of an ad hoc regional (i.e., Mediterranean algorithm for Chl concentration retrieval, also accounting for the difference between offshore (i.e., Case I and coastal (i.e., Case II waters. We apply the Mann-Kendall test and the Sens's method for trend estimation to the Chl concentration de-seasonalized monthly time series, as obtained from the X-11 technique. We also provide a preliminary analysis of some particular trends by evaluating their associated inter-annual variability. The high spatial resolution of our approach allows a clear identification of intense trends in those coastal waters that are affected by river outflows. We do not attempt to attribute the observed trends to specific anthropogenic events. However

  15. On the sub-maximal yield and photo-electric stimulation of chlorophyll a fluorescence in single turnover excitations in plant cells

    NARCIS (Netherlands)

    Vredenberg, W.J.; Rensen, van J.J.S.; Rodrigues, G.C.

    2006-01-01

    A set of expressions is derived which quantifies the chlorophyll fluorescence yield in terms of rate constants of primary light reactions of PSII, the fraction of open and semi-open RCs and of the electric field sensed by the RC in the thylakoid membrane. The decay kinetics of the chlorophyll

  16. Microdroplet fusion mass spectrometry: accelerated kinetics of acid-induced chlorophyll demetallation.

    Science.gov (United States)

    Lee, Jae Kyoo; Nam, Hong Gil; Zare, Richard N

    2017-01-01

    Kinetics of acid-induced chlorophyll demetallation was recorded in microdroplets by fusing a stream of microdroplets containing 40 µM chlorophyll a or b dissolved in methanol with a stream of aqueous microdroplets containing 35 mM hydrochloric acid (pH = 1·46). The kinetics of the demetallation of chlorophyll in the fused microdroplets (14 ± 6 µm diameter; 84 ± 18 m s-1 velocity) was recorded by controlling the traveling distance of the fused microdroplets between the fusion region and the inlet of a mass spectrometer. The rate of acid-induced chlorophyll demetallation was about 960 ± 120 times faster in the charged microdroplets compared with that reported in bulk solution. If no voltage was applied to the sprayed microdroplets, then the acceleration factor was about 580 ± 90, suggesting that the applied voltage is not a major factor determining the acceleration. Chlorophyll a was more rapidly demetallated than chlorophyll b by a factor of ~26 in bulk solution and ~5 in charged microdroplets. The demetallation kinetics was second order in the H+ concentration, but the acceleration factor of microdroplets compared with bulk solution appeared to be unchanged in going from pH = 1·3 to 7·0. The water:methanol ratio of the fused microdroplets was varied from 7:3 to 3:7 causing an increase in the reaction rate of chlorophyll a demetallation by 20%. This observation demonstrates that the solvent composition, which has different evaporation rates, does not significantly affect the acceleration. We believe that a major portion of the acceleration can be attributed to confinement effects involving surface reactions rather than either to evaporation of solvents or to the introduction of charges to the microdroplets.

  17. Purple-bacterial photosynthetic reaction centers and quantum-dot hybrid-assemblies in lecithin liposomes and thin films.

    Science.gov (United States)

    Lukashev, Eugeny P; Knox, Petr P; Gorokhov, Vladimir V; Grishanova, Nadezda P; Seifullina, Nuranija Kh; Krikunova, Maria; Lokstein, Heiko; Paschenko, Vladimir Z

    2016-11-01

    Quantum dots (QDs) absorb ultraviolet and long-wavelength visible light energy much more efficiently than natural bacterial light-harvesting proteins and can transfer the excitation energy to photosynthetic reaction centers (RCs). Inclusion of RCs combined with QDs as antennae into liposomes opens new opportunities for using such hybrid systems as a basis for artificial energy-transforming devices that potentially can operate with greater efficiency and stability than devices based only on biological components or inorganic components alone. RCs from Rhodobacter sphaeroides and QDs (CdSe/ZnS with hydrophilic covering) were embedded in lecithin liposomes by extrusion of a solution of multilayer lipid vesicles through a polycarbonate membrane or by dialysis of lipids and proteins dispersed with excess detergent. The efficiency of RC and QD interaction within the liposomes was estimated using fluorescence excitation spectra of the photoactive bacteriochlorophyll of the RCs and by measuring the fluorescence decay kinetics of the QDs. The functional activity of the RCs in hybrid complexes was fully maintained, and their stability was even increased. The efficiency of energy transfer between QDs and RCs and conditions of long-term stability of function of such hybrid complexes in film preparations were investigated as well. It was found that dry films containing RCs and QDs, maintained at atmospheric humidity, are capable of maintaining their functional activity for at least some months as judged by measurements of their spectral characteristics, efficiency of energy transfer from QDs to RCs and RC electron transport activity. Addition of trehalose to the films increases the stability further, especially for films maintained at low humidity. These stable hybrid film structures are promising for further studies towards developing new phototransformation devices for biotechnological applications. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Photosynthesis Is Widely Distributed among Proteobacteria as Demonstrated by the Phylogeny of PufLM Reaction Center Proteins

    Directory of Open Access Journals (Sweden)

    Johannes F. Imhoff

    2018-01-01

    Full Text Available Two different photosystems for performing bacteriochlorophyll-mediated photosynthetic energy conversion are employed in different bacterial phyla. Those bacteria employing a photosystem II type of photosynthetic apparatus include the phototrophic purple bacteria (Proteobacteria, Gemmatimonas and Chloroflexus with their photosynthetic relatives. The proteins of the photosynthetic reaction center PufL and PufM are essential components and are common to all bacteria with a type-II photosynthetic apparatus, including the anaerobic as well as the aerobic phototrophic Proteobacteria. Therefore, PufL and PufM proteins and their genes are perfect tools to evaluate the phylogeny of the photosynthetic apparatus and to study the diversity of the bacteria employing this photosystem in nature. Almost complete pufLM gene sequences and the derived protein sequences from 152 type strains and 45 additional strains of phototrophic Proteobacteria employing photosystem II were compared. The results give interesting and comprehensive insights into the phylogeny of the photosynthetic apparatus and clearly define Chromatiales, Rhodobacterales, Sphingomonadales as major groups distinct from other Alphaproteobacteria, from Betaproteobacteria and from Caulobacterales (Brevundimonas subvibrioides. A special relationship exists between the PufLM sequences of those bacteria employing bacteriochlorophyll b instead of bacteriochlorophyll a. A clear phylogenetic association of aerobic phototrophic purple bacteria to anaerobic purple bacteria according to their PufLM sequences is demonstrated indicating multiple evolutionary lines from anaerobic to aerobic phototrophic purple bacteria. The impact of pufLM gene sequences for studies on the environmental diversity of phototrophic bacteria is discussed and the possibility of their identification on the species level in environmental samples is pointed out.

  19. Identification of protein W, the elusive sixth subunit of the Rhodopseudomonas palustris reaction center-light harvesting 1 core complex.

    Science.gov (United States)

    Jackson, Philip J; Hitchcock, Andrew; Swainsbury, David J K; Qian, Pu; Martin, Elizabeth C; Farmer, David A; Dickman, Mark J; Canniffe, Daniel P; Hunter, C Neil

    2018-02-01

    The X-ray crystal structure of the Rhodopseudomonas (Rps.) palustris reaction center-light harvesting 1 (RC-LH1) core complex revealed the presence of a sixth protein component, variably referred to in the literature as helix W, subunit W or protein W. The position of this protein prevents closure of the LH1 ring, possibly to allow diffusion of ubiquinone/ubiquinol between the RC and the cytochrome bc 1 complex in analogous fashion to the well-studied PufX protein from Rhodobacter sphaeroides. The identity and function of helix W have remained unknown for over 13years; here we use a combination of biochemistry, mass spectrometry, molecular genetics and electron microscopy to identify this protein as RPA4402 in Rps. palustris CGA009. Protein W shares key conserved sequence features with PufX homologs, and although a deletion mutant was able to grow under photosynthetic conditions with no discernible phenotype, we show that a tagged version of protein W pulls down the RC-LH1 complex. Protein W is not encoded in the photosynthesis gene cluster and our data indicate that only approximately 10% of wild-type Rps. palustris core complexes contain this non-essential subunit; functional and evolutionary consequences of this observation are discussed. The ability to purify uniform RC-LH1 and RC-LH1-protein W preparations will also be beneficial for future structural studies of these bacterial core complexes. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  20. Severity of mutant phenotype in a series of chlorophyll-deficient wheat mutants depends on light intensity and the severity of the block in chlorophyll synthesis.

    Science.gov (United States)

    Falbel, T G; Meehl, J B; Staehelin, L A

    1996-10-01

    Analyses of a series of allelic chlorina mutants of wheat (Triticum aestivum L.), which have partial blocks in chlorophyll (Chl) synthesis and, therefore, a limited Chl supply, reinforce the principle that Chl is required for the stable accumulation of Chl-binding proteins and that only reaction centers accumulate when the supply of Chl is severely limited. Depending on the rate of Chl accumulation (determined by the severity of the mutation) and on the rate of turnover of Chl and its precursors (determined by the environment in which the plant is grown), the mutants each reach an equilibrium of Chl synthesis and degradation. Together these mutants generate a spectrum of phenotypes. Under the harshest conditions (high illumination), plants with moderate blocks in Chl synthesis have membranes with very little Chl and Chl-proteins and membrane stacks resembling the thylakoids of the lethal xantha mutants of barely grown at low to medium light intensities (which have more severe blocks). In contrast, when grown under low-light conditions the same plants with moderate blocks have thylakoids resembling those of the wild type. The wide range of phenotypes of Chl b-deficient mutants has historically produced more confusion than enlightenment, but incomparable growth conditions can now explain the discrepancies reported in the literature.

  1. Investigations on gamma ray induced chlorophyll variegated mutants

    International Nuclear Information System (INIS)

    Datta, S.K.; Dwivedi, A.K.; Banerji, B.K.

    1995-01-01

    Considering economic importance of chlorophyll variegation in floriculture trade an attempt was made for cytological, anatomical and biochemical analysis of four Bougainvillea and Lantana depressa chlorophyll variegated mutants for better and clear understanding of origin of chlorophyll variegation. No cytological evidence could be detected for their origin. Anatomical and biochemical examinations revealed that chlorophyll variegation in these mutants were due to changes in biosynthesis pathways and time of chlorophyll synthesis in palisade and spongy mesophyll cells. (author). 7 refs., 3 figs., 3 tabs

  2. [Prevalence of reactions secundary to mosquito bites Aedes aegypti at en el Regional Center of Allergy and Clinical Immunology, University Hospital, de Monterrey, Nuevo Leon].

    Science.gov (United States)

    González Diaz, Sandra Nora; Cruz, Alfredo Arias; Sedó Mejía, Giovanni A; Rojas Lozano, Antonio A; Valenzuela, Enrique Avitia; Vidaurri Ojeda, Alma C

    2010-01-01

    although systemic reactions resulting from hymenoptera stings have been studied extensively, the prevalence of allergic reactions to mosquitoes is unknown. to investigate the prevalence of allergic reactions to Aedes aegypti bites in patients seeking treatment at the Allergy and Clinical Immunology Regional Center of Jose E Gonzalez University Hospital in Monterrey, Mexico. we carried out a cross-sectional, descriptive study that included patients receiving skin tests for aeroallergens; skin sensitivity to mosquito bites was also tested. A questionnaire was used to obtain information about previous allergic reactions to mosquito bites. a total of 482 patients between 2 and 60 years of age were included; 53% were female, 407 (84.4%) had a history of local reactions to mosquito bites. Twelve patients (2.4%) stated a history of large local reaction; three (0.6%) of them with a positive skin prick test, one (0.2%) of those had systemic reaction history to mosquito. Eighty five (17.6%) patients had a positive mosquito skin test and 307 (63.6%) had a positive skin test for at least one aeroallergen. Seventy-eight (91.7%) of the 85 patients with a positive mosquito skin test had a history of local skin reactions to mosquito bite (odds ratio: 2.303 [confidence interval (CI) 1.037-5.10]. There was no statistically significance association between allergic diseases and mosquito allergy. adverse reactions and allergic reactions to mosquito bites occur frequently. However mosquito allergy is low. Further studies are required to determine the prevalence of mosquito allergy in the general population.

  3. Recent Trends in Global Ocean Chlorophyll

    Science.gov (United States)

    Gregg, Watson; Casey, Nancy

    2004-01-01

    Recent analyses of SeaWiFS data have shown that global ocean chlorophyll has increased more than 5% since 1998. The North Pacific ocean basin has increased nearly 19%. To understand the causes of these trends we have applied the newly developed NASA Ocean Biogeochemical Assimilation Model (OBAM), which is driven in mechanistic fashion by surface winds, sea surface temperature, atmospheric iron deposition, sea ice, and surface irradiance. The mode1 utilizes chlorophyll from SeaWiFS in a daily assimilation. The model has in place many of the climatic variables that can be expected to produce the changes observed in SeaWiFS data. Ths enables us to diagnose the model performance, the assimilation performance, and possible causes for the increase in chlorophyll.

  4. The spontaneous chlorophyll mutation frequency in barley

    DEFF Research Database (Denmark)

    Jørgensen, Jørgen Helms; Jensen, Hans Peter

    1986-01-01

    A total of 1866 barley plants were progeny tested in the greenhouse. Twenty-five plants segregated for newly arisen, spontaneous chlorophyll mutant genes. Among the total of 470,129 seedlings screened there were 79 mutants (1.7 .+-. 0.6 .times. 10-4). The data are added to data from three similar...... materials and the resulting estimate of the chlorophyll mutant frequency is 1.6 .times. 10-4 in about 1.43 million seedlings. The estimate of the chlorophyll mutation rate per generation is close to 67.3 .times. 10-4 per diploid genome or in the order of 6 .times. 10-7 per locus and haploid genome....

  5. Comparison of calculated and experimental isotope edited FTIR difference spectra for purple bacterial photosynthetic reaction centers with different quinones incorporated into the QA binding site.

    Directory of Open Access Journals (Sweden)

    Nan eZhao

    2013-08-01

    Full Text Available Previously we have shown that ONIOM type (QM/MM calculations can be used to simulate isotope edited FTIR difference spectra for neutral ubiquinone in the QA binding site in Rhodobacter sphaeroides photosynthetic reaction centers. Here we considerably extend upon this previous work by calculating isotope edited FTIR difference spectra for reaction centers with a variety of unlabeled and 18O labeled foreign quinones incorporated into the QA binding site. Isotope edited spectra were calculated for reaction centers with 2,3-dimethoxy-5,6-dimethyl-1,4-benzoquinone (MQ0, 2,3,5,6-tetramethyl-1,4-benzoquinone (duroquinone, DQ, and 2,3-dimethyl-l,4-naphthoquinone (DMNQ incorporated, and compared to corresponding experimental spectra. The calculated and experimental spectra agree well, further demonstrating the utility and applicability of our ONIOM approach for calculating the vibrational properties of pigments in protein binding sites.The normal modes that contribute to the bands in the calculated spectra, their composition, frequency and intensity, and how these quantities are modified upon 18O labeling, are presented. This computed information leads to a new and more detailed understanding/interpretation of the experimental FTIR difference spectra. Hydrogen bonding to the carbonyl groups of the incorporated quinones is shown to be relatively weak. It is also shown that there is some asymmetry in hydrogen bonding, accounting for 10-13 cm-1 separation in the frequencies of the carbonyl vibrational modes of the incorporated quinones. The extent of asymmetry H-bonding could only be established by considering the spectra for various types of quinones incorporated into the QA binding site. The quinones listed above are tail-less. Spectra were also calculated for reaction centers with corresponding tail containing quinones incorporated, and it is found that replacement of the quinone methyl group by a phytyl or prenyl chain does not alter ONIOM calculated s

  6. Chlorophyll mutants in Phaseolus vulgaris (L.) Savi

    International Nuclear Information System (INIS)

    Svetleva, D.; Petkova, S.

    1991-01-01

    Three-year investigations were conducted on chlorophyll mutants of three type: viridissima, claroviridis, flavoviridis, viridocostata and xanthomarginata produced post gamma irradiation ( 60 Co, 8 krad, 280 rad/min). Cell division rate in spectrum and in quantity of induced aberrations was found to have no significant differences with the control. Chlorophyll mutations compared to the control are less developed and their productive characters are less manifested. Cell division rate and the quantity of induced aberrations have no relation to the elements of productivity in the mutants investigated. 3 tabs., 12 refs

  7. Identification of a Chlorophyll Dephytylase Involved in Chlorophyll Turnover in Arabidopsis[OPEN

    Science.gov (United States)

    2016-01-01

    Chlorophyll turns over in green organs during photosystem repair and is salvaged via de- and rephytylation, but the enzyme involved in dephytylation is unknown. We have identified an Arabidopsis thaliana thylakoid protein with a putative hydrolase domain that can dephytylate chlorophyll in vitro and in vivo. The corresponding locus, CHLOROPHYLL DEPHYTYLASE1 (CLD1), was identified by mapping a semidominant, heat-sensitive, missense allele (cld1-1). CLD1 is conserved in oxygenic photosynthetic organisms, sharing structural similarity with pheophytinase, which functions in chlorophyll breakdown during leaf senescence. Unlike pheophytinase, CLD1 is predominantly expressed in green organs and can dephytylate chlorophyll in vitro. The specific activity is significantly higher for the mutant protein encoded by cld1-1 than the wild-type enzyme, consistent with the semidominant nature of the cld1-1 mutation. Supraoptimal CLD1 activities in cld1-1 mutants and transgenic seedlings led to the proportional accumulation of chlorophyllides derived from chlorophyll dephytylation after heat shock, which resulted in light-dependent cotyledon bleaching. Reducing CLD1 expression diminished thermotolerance and the photochemical efficiency of photosystem II under prolonged moderate heat stress. Taken together, our results suggest that CLD1 is the long-sought enzyme for removing the phytol chain from chlorophyll during its turnover at steady state within the chloroplast. PMID:27920339

  8. Identification of a Chlorophyll Dephytylase Involved in Chlorophyll Turnover in Arabidopsis.

    Science.gov (United States)

    Lin, Yao-Pin; Wu, Meng-Chen; Charng, Yee-Yung

    2016-12-01

    Chlorophyll turns over in green organs during photosystem repair and is salvaged via de- and rephytylation, but the enzyme involved in dephytylation is unknown. We have identified an Arabidopsis thaliana thylakoid protein with a putative hydrolase domain that can dephytylate chlorophyll in vitro and in vivo. The corresponding locus, CHLOROPHYLL DEPHYTYLASE1 (CLD1), was identified by mapping a semidominant, heat-sensitive, missense allele (cld1-1). CLD1 is conserved in oxygenic photosynthetic organisms, sharing structural similarity with pheophytinase, which functions in chlorophyll breakdown during leaf senescence. Unlike pheophytinase, CLD1 is predominantly expressed in green organs and can dephytylate chlorophyll in vitro. The specific activity is significantly higher for the mutant protein encoded by cld1-1 than the wild-type enzyme, consistent with the semidominant nature of the cld1-1 mutation. Supraoptimal CLD1 activities in cld1-1 mutants and transgenic seedlings led to the proportional accumulation of chlorophyllides derived from chlorophyll dephytylation after heat shock, which resulted in light-dependent cotyledon bleaching. Reducing CLD1 expression diminished thermotolerance and the photochemical efficiency of photosystem II under prolonged moderate heat stress. Taken together, our results suggest that CLD1 is the long-sought enzyme for removing the phytol chain from chlorophyll during its turnover at steady state within the chloroplast. © 2016 American Society of Plant Biologists. All rights reserved.

  9. Evolution of direct mechanisms with incident energy from the Coulomb-barrier to relativistic energies. - Two-center effects in nucleon transfer between nuclei. - Signatures of nucleon promotion in heavy ion reactions at barrier energies

    International Nuclear Information System (INIS)

    Oertzen, W. von; Voit, H.; Imanishi, B.

    1988-10-01

    This report contains a review article considering the evolution of direct mechanisms with incident energy in heavy ion reactions and two theoretical articles concerning two-center effects in transfer reactions between heavy ions and the nucleon promotion in heavy ion reactions. See hints under the relevant topics. (HSI)

  10. Identification of Genes Associated with Chlorophyll Accumulation in Flower Petals

    Science.gov (United States)

    Ohmiya, Akemi; Hirashima, Masumi; Yagi, Masafumi; Tanase, Koji; Yamamizo, Chihiro

    2014-01-01

    Plants have an ability to prevent chlorophyll accumulation, which would mask the bright flower color, in their petals. In contrast, leaves contain substantial amounts of chlorophyll, as it is essential for photosynthesis. The mechanisms of organ-specific chlorophyll accumulation are unknown. To identify factors that determine the chlorophyll content in petals, we compared the expression of genes related to chlorophyll metabolism in different stages of non-green (red and white) petals (very low chlorophyll content), pale-green petals (low chlorophyll content), and leaves (high chlorophyll content) of carnation (Dianthus caryophyllus L.). The expression of many genes encoding chlorophyll biosynthesis enzymes, in particular Mg-chelatase, was lower in non-green petals than in leaves. Non-green petals also showed higher expression of genes involved in chlorophyll degradation, including STAY-GREEN gene and pheophytinase. These data suggest that the absence of chlorophylls in carnation petals may be caused by the low rate of chlorophyll biosynthesis and high rate of degradation. Similar results were obtained by the analysis of Arabidopsis microarray data. In carnation, most genes related to chlorophyll biosynthesis were expressed at similar levels in pale-green petals and leaves, whereas the expression of chlorophyll catabolic genes was higher in pale-green petals than in leaves. Therefore, we hypothesize that the difference in chlorophyll content between non-green and pale-green petals is due to different levels of chlorophyll biosynthesis. Our study provides a basis for future molecular and genetic studies on organ-specific chlorophyll accumulation. PMID:25470367

  11. Afterglow of chlorophyll in vivo and photosynthesis

    NARCIS (Netherlands)

    Goedheer, J.C.

    1962-01-01

    Two pigment systems are involved in the afterglow of chlorophyll a-containing cells. Absorption in only one of these systems (promoting or “p” system) is effective in producing luminescence. If light is absorbed simultaneously by the other (quenching or “q” system), a decrease in luminescence

  12. SHORT COMMUNICATION ISOLATION OF CHLOROPHYLL A ...

    African Journals Online (AJOL)

    a

    chromatography (CCC) technique has been applied to the separation of chlorophyll a from ... auxiliary gas flow rate, 0.06 L min-1; ion spray voltage, 3.5 kV; capillary .... This work presents a successful application of column chromatography ...

  13. Spectral characteristics and colloidal properties of chlorophyll a{prime} in aqueous methanol

    Energy Technology Data Exchange (ETDEWEB)

    Oba, Toru [Ritsumeikan Univ., Kusatsu (Japan); Mimuro, Mamoru [National Inst. for Basic Biology, Okazaki (Japan); Wang, Z.Y.; Nozawa, Tsunenori [Tohoku Univ., Sendai (Japan); Yoshida, Shoichiro; Watanabe, Tadashi [Univ. of Tokyo (Japan)

    1997-04-17

    The `phase behavior` of chlorophyll a` (Chl a`, C13{sup 2}-epimer of Chl a) dissolved in aqueous methanol was examined in terms of the composition of the solvent. The study aimed at elucidating the property of Chl a`, the exotic pigment found in a photosynthetic reaction center complex, as well as at clarifying the nature of the Chl aggregation in aqueous media. Visible absorption, circular dichroism (CD), fluorescence and resonance Raman spectroscopies, dynamic light-scattering measurements, and electron microscopy were utilized. Chl a` formed either of two types of colloids depending on the solvent composition. The one formed over a wide methanol volume percentage (ca. 73-30%) commonly possessed a single microscopic structural unit that yielded the double-peaked absorption (ca. 690 and 715 nm) accompanied by a symmetric dispersed-type CD spectrum. Increasing methanol concentration within this solvent composition range enhanced the size of the colloid and finally caused critical opalescence, which was reminiscent of the critical behavior of the aqueous solution of nonionic surfactants. These findings indicate that the microscopic structure of the Chl a` aggregate was independent of the size and shape of the colloid. The difference between the aggregation behaviors of Chl a and a` suggests a narrower choice of possible molecular arrangements in the Chl a` aggregate as an inherent property of the pigment. 37 refs., 11 figs.

  14. Nuclear Data Center (NDC) of Korea Atomic Energy Research Institute (KAERI). Progress Report to the IAEA Technical Meeting of Nuclear Reaction Data Centers (NRDC)

    International Nuclear Information System (INIS)

    Lee, Young-Ouk

    2012-01-01

    Nuclear Data Center (NDC, former Nuclear Data Evaluation Lab.) of Korea Atomic Energy Research Institute (KAERI) has a director, 10 permanent staffs (2 in evaluation, 1 in measurement, 2 in atomic and molecular data, 2 in processing and validation, 3 in applications), one PhD student and one secretary. KAERI/NDC recently expanded its scope of work into the atomic and molecular data where two permanent staffs are involved. Mission of KAERI/NDC is disseminating outcomes of international network as well as promoting domestic nuclear data activities and related applications.

  15. Overview of remote sensing of chlorophyll flourescene in ocean waters

    African Journals Online (AJOL)

    Overview of remote sensing of chlorophyll flourescene in ocean waters. ... Besides empirical algorithms with the blue-green ratio, the algorithms based on ... between fluorescence and chlorophyll concentration and the red shift phenomena.

  16. Comprehensive chlorophyll composition in the main edible seaweeds.

    Science.gov (United States)

    Chen, Kewei; Ríos, José Julián; Pérez-Gálvez, Antonio; Roca, María

    2017-08-01

    Natural chlorophylls present in seaweeds have been studied regarding their biological activities and health benefit effects. However, detailed studies regarding characterization of the complete chlorophyll profile either qualitatively and quantitatively are scarce. This work deals with the comprehensive spectrometric study of the chlorophyll derivatives present in the five main coloured edible seaweeds. The novel complete MS 2 characterization of five chlorophyll derivatives: chlorophyll c 2 , chlorophyll c 1 , purpurin-18 a, pheophytin d and phytyl-purpurin-18 a has allowed to obtain fragmentation patterns associated with their different structural features. New chlorophyll derivatives have been identified and quantified by first time in red, green and brown seaweeds, including some oxidative structures. Quantitative data of the chlorophyll content comes to achieve significant information for food composition databases in bioactive compounds. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Characterization of hypersensitivity reactions reported among Andrographis paniculata users in Thailand using Health Product Vigilance Center (HPVC) database.

    Science.gov (United States)

    Suwankesawong, Wimon; Saokaew, Surasak; Permsuwan, Unchalee; Chaiyakunapruk, Nathorn

    2014-12-24

    Andrographis paniculata (andrographis) is one of the herbal products that are widely used for various indications. Hypersensitivity reactions have been reported among subjects receiving Andrographis paniculata in Thailand. Understanding of characteristics of patients, adverse events, and clinical outcomes is essential for ensuring population safety.This study aimed to describe the characteristics of hypersensitivity reactions reported in patients receiving andrographis containing products in Thailand using national pharmacovigilance database. Thai Vigibase data from February 2001 to December 2012 involving andrographis products were used. This database includes the reports submitted through the spontaneous reporting system and intensive monitoring programmes. The database contained patient characteristic, adverse events associated with andrographis products, and details on seriousness, causality, and clinical outcomes. Case reports were included for final analysis if they met the inclusion criteria; 1) reports with andrographis being the only suspected cause, 2) reports with terms consistent with the constellation of hypersensitivity reactions, and 3) reports with terms considered critical terms according to WHO criteria. Descriptive statistics were used. A total of 248 case reports of andrographis-associated adverse events were identified. Only 106 case reports specified andrographis herbal product as the only suspected drug and reported at least one term consistent with constellation of hypersensitivity reactions. Most case reports (89%) came from spontaneous reporting system with no previously documented history of drug allergy (88%). Of these, 18 case reports were classified as serious with 16 cases requiring hospitalization. For final assessment, the case reports with terms consistent with constellation of hypersensitivity reactions and critical terms were included. Thirteen case reports met such criteria including anaphylactic shock (n = 5), anaphylactic

  18. Excitation energy transfer in natural photosynthetic complexes and chlorophyll trefoils: hole-burning and single complex/trefoil spectroscopic studies

    Energy Technology Data Exchange (ETDEWEB)

    Ryszard Jankowiak, Kansas State University, Department of Chemistry, CBC Bldg., Manhattan KS, 66505; Phone: (785) 532-6785

    2012-09-12

    In this project we studied both natural photosynthetic antenna complexes and various artificial systems (e.g. chlorophyll (Chl) trefoils) using high resolution hole-burning (HB) spectroscopy and excitonic calculations. Results obtained provided more insight into the electronic (excitonic) structure, inhomogeneity, electron-phonon coupling strength, vibrational frequencies, and excitation energy (or electron) transfer (EET) processes in several antennas and reaction centers. For example, our recent work provided important constraints and parameters for more advanced excitonic calculations of CP43, CP47, and PSII core complexes. Improved theoretical description of HB spectra for various model systems offers new insight into the excitonic structure and composition of low-energy absorption traps in very several antenna protein complexes and reaction centers. We anticipate that better understanding of HB spectra obtained for various photosynthetic complexes and their simultaneous fits with other optical spectra (i.e. absorption, emission, and circular dichroism spectra) provides more insight into the underlying electronic structures of these important biological systems. Our recent progress provides a necessary framework for probing the electronic structure of these systems via Hole Burning Spectroscopy. For example, we have shown that the theoretical description of non-resonant holes is more restrictive (in terms of possible site energies) than those of absorption and emission spectra. We have demonstrated that simultaneous description of linear optical spectra along with HB spectra provides more realistic site energies. We have also developed new algorithms to describe both nonresonant and resonant hole-burn spectra using more advanced Redfield theory. Simultaneous description of various optical spectra for complex biological system, e.g. artificial antenna systems, FMO protein complexes, water soluble protein complexes, and various mutants of reaction centers

  19. Chlorophyll catabolism in olive fruits (var. Arbequina and Hojiblanca) during maturation.

    Science.gov (United States)

    Vergara-Domínguez, Honorio; Ríos, José Julían; Gandul-Rojas, Beatriz; Roca, María

    2016-12-01

    The central reaction of chlorophyll (chl) breakdown pathway occurring during olive fruits maturation is the cleavage of the macrocycle pheophorbide a to a primary fluorescent chl catabolite (pFCC) and it is catalyzed by two enzymes: pheophorbide a oxygenase (PaO) and red chl catabolite reductase (RCCR). In subsequent steps, pFCC is converted to different fluorescent chlorophyll catabolites (FCCs) and nonfluorescent chlorophyll catabolites (NCCs). This work demonstrated that RCCR activity of olive fruits is type II. During the study of evolution of PaO and RCCR activities through the olive fruits maturation in two varieties: Hojiblanca and Arbequina, a significant increase in PaO and RCCR activity was found in ripening stage. In addition, the profile and structure of NCCs present in epicarp of this fruit was studied using HPLC/ESI-TOF-MS. Five different NCCs were defined and for the first time the enzymatic reactions implied in chlorophyll degradations in olive fruits elucidated. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. A review of ocean chlorophyll algorithms and primary production models

    Science.gov (United States)

    Li, Jingwen; Zhou, Song; Lv, Nan

    2015-12-01

    This paper mainly introduces the five ocean chlorophyll concentration inversion algorithm and 3 main models for computing ocean primary production based on ocean chlorophyll concentration. Through the comparison of five ocean chlorophyll inversion algorithm, sums up the advantages and disadvantages of these algorithm,and briefly analyzes the trend of ocean primary production model.

  1. Adverse reactions of Methylphenidate in children with attention deficit-hyperactivity disorder: Report from a referral center

    Science.gov (United States)

    Khajehpiri, Zahra; Mahmoudi-Gharaei, Javad; Faghihi, Toktam; Karimzadeh, Iman; Khalili, Hossein; Mohammadi, Mostafa

    2014-01-01

    Objective: The aim of the current study was to determine various aspects of methylphenidate adverse reactions in children with attention deficit-hyperactivity disorder (ADHD) in Iran. Methods: During the 6 months period, all children under methylphenidate treatment alone or along with other agents attending a university-affiliated psychology clinic were screened regarding all subjective and objective adverse drug reactions (ADRs) of methylphenidate. Causality and seriousness of detected ADRs were assessed by relevant World Health Organization definitions. The Schumock and Thornton questionnaire was used to determine preventability of ADRs. Findings: Seventy-one patients including 25 girls and 46 boys with ADHD under methylphenidate treatment were enrolled within the study period. All (100%) ADHD children under methylphenidate treatment developed at least one ADR. Anorexia (74.3%), irritability (57.1%), and insomnia (47.2%) were the most frequent methylphenidate-related adverse reactions. Except for one, all other detected ADRs were determined to be mild. In addition, no ADR was considered to be preventable and serious. Conclusion: Our data suggested that although methylphenidate related adverse reactions were common in children with ADHD, but they were mainly mild and nonserious. PMID:25535621

  2. Probing the Energy Transfer Dynamics of Photosynthetic Reaction Center Complexes Through Hole-Burning and Single-Complex Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Riley, Kerry Joseph [Iowa State Univ., Ames, IA (United States)

    2007-01-01

    Photosynthesis is the process by which light energy is used to drive reactions that generate sugars to supply energy for cellular processes. It is one of the most important fundamental biological reactions and occurs in both prokaryotic (e.g. bacteria) and eukaryotic (e.g. plants and algae) organisms. Photosynthesis is also remarkably intricate, requiring the coordination of many different steps and reactions in order to successfully transform absorbed solar energy into a biochemical usable form of energy. However, the net reaction for all photosynthetic organisms can be reduced to the following, deceptively general, equation developed by Van Niel[1] H2 - D + Aimplieshv A - H2 + D where H2-D is the electron donor, e.g. H2O, H2S. A is the electron acceptor, e.g. CO2, and A-H2 is the synthesized sugar. Amazingly, this simple net equation is responsible for creating the oxidizing atmosphere of Earth and the recycling of CO2, both of which are necessary for the sustainment of the global ecosystem.

  3. Magnitude and direction of the change in dipole moment associated with excitation of the primary electron donor in Rhodopseudomonas sphaeroides reaction centers

    Energy Technology Data Exchange (ETDEWEB)

    Lockhart, D.J.; Boxer, S.G.

    1987-02-10

    The magnitude and direction of the change in dipole moment, ..delta mu.., associated with the Q/sub y/ transition of the dimeric primary electron donor (special pair or P870) in Rhodopseudomonas sphaeroides reaction centers have been measured by Stark spectroscopy at 20 /sup 0/C. The magnitude of ..delta mu.. is found to be f/sup -1/ (10.3 +/- 0.7) D, where f is a correction factor for the local dielectric properties of the protein matrix. With the spherical cavity approximation and an effective local dielectric constant of 2, f = 1.2, and absolute value of ..delta mu.. is 8.6 +/- 0.6 D. Absolute value of ..delta mu.. for the Q/sub y/ transition of the special pair is approximately a factor of 3.4 and 2 greater than for the monomeric bacteriochlorophylls and bacteriopheophytins, respectively, in the reaction center. The angle between ..delta mu.. and the transition dipole moment for excitation of the first singlet electron state of the special pair was found to be 24 +/- 2/sup 0/. The measured values are combined to suggest a physical model in which the lowest excited singlet state of the special pair has substantial charge-transfer character and where charge is separated between the two monomers comprising the dimeric special pair. This leads to the hypothesis that the first charge-separated state in bacterial photosynthesis is formed directly upon photoexcitation. These data provide stringent values for comparison with theoretical calculations of the electronic structure of the chromophores in the reaction center.

  4. Conformational differences between the methoxy groups of QA and QB site ubisemiquinones in bacterial reaction centers: a key role for methoxy group orientation in modulating ubiquinone redox potential.

    Science.gov (United States)

    Taguchi, Alexander T; O'Malley, Patrick J; Wraight, Colin A; Dikanov, Sergei A

    2013-07-09

    Ubiquinone is an almost universal, membrane-associated redox mediator. Its ability to accept either one or two electrons allows it to function in critical roles in biological electron transport. The redox properties of ubiquinone in vivo are determined by its environment in the binding sites of proteins and by the dihedral angle of each methoxy group relative to the ring plane. This is an attribute unique to ubiquinone among natural quinones and could account for its widespread function with many different redox complexes. In this work, we use the photosynthetic reaction center as a model system for understanding the role of methoxy conformations in determining the redox potential of the ubiquinone/semiquinone couple. Despite the abundance of X-ray crystal structures for the reaction center, quinone site resolution has thus far been too low to provide a reliable measure of the methoxy dihedral angles of the primary and secondary quinones, QA and QB. We performed 2D ESEEM (HYSCORE) on isolated reaction centers with ubiquinones (13)C-labeled at the headgroup methyl and methoxy substituents, and have measured the (13)C isotropic and anisotropic components of the hyperfine tensors. Hyperfine couplings were compared to those derived by DFT calculations as a function of methoxy torsional angle allowing estimation of the methoxy dihedral angles for the semiquinones in the QA and QB sites. Based on this analysis, the orientation of the 2-methoxy groups are distinct in the two sites, with QB more out of plane by 20-25°. This corresponds to an ≈50 meV larger electron affinity for the QB quinone, indicating a substantial contribution to the experimental difference in redox potentials (60-75 mV) of the two quinones. The methods developed here can be readily extended to ubiquinone-binding sites in other protein complexes.

  5. Genetic analysis of sunflower chlorophyll mutants

    International Nuclear Information System (INIS)

    Mashkina, E.V.; Guskov, E.P.

    2001-01-01

    The method of getting the chlorophyll mutations in sunflower was developed by Y.D. Beletskii in 1969 with the use of N-nitroso-N-methylurea (NMH). Certain concentrations of NMH are known to induce plastid mutations in growing seeds, and their yield depends on the duration of the exposure. The given work presented studies on the influence of rifampicin (R) and 2,4-dinitrophenol (DNP) on the genetic activity NMH, as an inductor of plastid and nuclear mutations

  6. Wind driven nutrient and subsurface chlorophyll-a enhancement in the Bay of La Paz, Gulf of California

    Science.gov (United States)

    Coria-Monter, Erik; Monreal-Gómez, María Adela; Salas de León, David Alberto; Durán-Campos, Elizabeth; Merino-Ibarra, Martín

    2017-09-01

    Nutrient and chlorophyll-a distributions in the Bay of La Paz, Gulf of California, Mexico were analyzed during the late spring of 2004 to assess their relations to hydrography and circulation patterns. The results show the presence of both Gulf of California Water and Subtropical Subsurface Water. Water circulation was dominated by wind stress driven cyclonic circulation along f / H contours (f is planetary vorticity and H is depth), and upwelling resulting from the divergence shows a vertical velocity of ∼0.4 m d-1. Nutrient concentrations were higher in the center of the cyclonic pattern, where a rise in the nutricline contributed nutrients to the euphotic layer as a result of Ekman pumping. The vertical section showed the presence of a chlorophyll-a maximum at the thermocline shoaling to a depth of only 12 m. Along the surface, two peaks of chlorophyll-a were observed, one at Boca Grande and another off San Juan de la Costa, associated with upwelling and mixing derived from current interactions with abrupt topographies. The chlorophyll-a maximum increased from 0.8 mg m-3 in the external part of the cyclonic pattern to 2.0 mg m-3 in its center. The vertically integrated chlorophyll-a concentrations followed a similar pattern, rising from 10 to 20 mg m-2 and reaching their highest values in the center of the cyclonic circulation pattern. A schematic model was developed to describe processes that occur in late spring: the wind stress driven cyclonic structure promotes upward nutrient flux, which in turn drives an enhancement of chlorophyll-a. Upwelling was found to be the main mechanism of fertilization responsible for the enhancement of productivity levels by means of nutrient transport into the euphotic zone during spring. Other chlorophyll enhancement areas point to the occurrence of additional fertilization processes that may derive from interactions between cyclonic circulation patterns and the topography off of San Juan de la Costa, where phosphate mining

  7. Report on the consultants` meeting on co-ordination of the nuclear reaction data centers (technical aspects)

    Energy Technology Data Exchange (ETDEWEB)

    Schwerer, O; Wienke, H [eds.

    1997-10-01

    The report summarizes the co-ordination meeting of the network of Nuclear Reaction Data Centres organized by the IAEA in 1997. The meeting was attended by technical staff from ten member centres of the network (representing USA, Russia, China, Japan, Hungary, OECD-NEA and IAEA) to discuss technical matters of the nuclear data compilation and exchange by means of the jointly operated computerized systems CINDA, EXFOR, ENDF and others. Observers from Belgium and Ukraine also attended the meeting. The document includes status reports of all centres and selected working papers. Refs, figs, tabs.

  8. Report on the consultants' meeting on co-ordination of the nuclear reaction data centers (technical aspects)

    International Nuclear Information System (INIS)

    Schwerer, O.; Wienke, H.

    1997-10-01

    The report summarizes the co-ordination meeting of the network of Nuclear Reaction Data Centres organized by the IAEA in 1997. The meeting was attended by technical staff from ten member centres of the network (representing USA, Russia, China, Japan, Hungary, OECD-NEA and IAEA) to discuss technical matters of the nuclear data compilation and exchange by means of the jointly operated computerized systems CINDA, EXFOR, ENDF and others. Observers from Belgium and Ukraine also attended the meeting. The document includes status reports of all centres and selected working papers

  9. One-electron oxidation of photosynthetic pigments in micelles. Bacteriochlorophyll a, chlorophyll a, chlorophyll b, and pheophytin a

    International Nuclear Information System (INIS)

    Chauvet, J.P.

    1981-01-01

    Chlorophyll a, chlorophyll b, and bacteriochlorophyll a in aqueous micellar solutions of Trition X 100 (2%) are readily oxidized by pulse-radiolytically generated N 3 ., Br 2 - ., and (SCN) 2 - . radicals at nearly diffusion-controlled rates. The kinetic study suggests that pigment molecules occupy multiple sites in the micelle. Pheophytin a is only oxidized by N 3 . and Br 2 - . radicals. The absolute spectra and the molar extinction coefficients of chlorophyll a, bacteriochlorophyll a, chlorophyll b, and pheophytin a cations have been determined. The chlorophyll a cation has been observed in the presence of pigment aggregates

  10. Chlorophyllase in Piper betle L. has a role in chlorophyll homeostasis and senescence dependent chlorophyll breakdown.

    Science.gov (United States)

    Gupta, Supriya; Gupta, Sanjay Mohan; Sane, Aniruddha P; Kumar, Nikhil

    2012-06-01

    Total chlorophyll content and chlorophyllase (chlorophyll-chlorophyllido hydrolase EC 3.1.1.14) activity in fresh leaves of Piper betle L. landrace KS was, respectively, twofold higher and eight fold lower than KV, showing negative correlation between chlorophyll and chlorophyllase activity. Specific chlorophyllase activity was nearly eightfold more in KV than KS. ORF of 918 nt was found in cloned putative chlorophyllase cDNAs from KV and KS. The gene was present as single copy in both the landraces. The encoded polypeptide of 306 amino acids differed only at two positions between the KV and KS; 203 (cysteine to tyrosine) and 301 (glutamine to glycine). Difference in chlorophyllase gene expression between KV and KS was evident in fresh and excised leaves. Up regulation of chlorophyllase gene by ABA and down regulation by BAP was observed in both the landraces; however, there was quantitative difference between KV and KS. Data suggests that chlorophyllase in P. betle is involved in chlorophyll homeostasis and chlorophyll loss during post harvest senescence.

  11. THE USE OF CHLOROPHYLL FLUORESCENCE «a» FOR BIOTESTING OF THE AQUATIC ENVIRONMENT

    Directory of Open Access Journals (Sweden)

    V. A. Osipov

    2012-01-01

    Full Text Available The impact on marine algae Thalassiosiraweisflogii, Pseudo-nitzshiadelicatissima of copper sulfate, chloride of mercury, methylmercury were studied. Found a sharp increase sensitivity FS 2 of microalgae cultures and natural phytoplankton to salts of heavy metals in the conditions of the light of the stress that is associated with inhibition of protein synthetic reactions. Conclusions are made about the prospects of the use of fluorescence of chlorophyll "a" for biotesting.

  12. Study of the Mn-binding sites in photosystem II using antibodies raised against lumenal regions of the D1 and D2 reaction center proteins

    Energy Technology Data Exchange (ETDEWEB)

    Dalmasso, Enrique Agustin [Univ. of California, Berkeley, CA (United States)

    1992-04-01

    The experiments discussed in this thesis focus on identifying the protein segments or specific amino acids which provide ligands to the Mn cluster of photosystem II (PS II). This Mn cluster plays a central role in the oxygen-evolving complex (OEC) of PS II. The Mn cluster is thought to be bound by lumenal regions of the PS II reaction center proteins known as D1 and D2. First, several peptides were synthesized which correspond to specific lumenal segments of the D1 and D2 proteins. Next, polyclonal antibodies were successfully elicited using three of these peptides. The peptides recognized by these antibodies correspond to protein segments of the spinach reaction center proteins: Ile-321 to Ala-344 of D1 (D1-a), Asp-319 to Arg-334 of D1 (D1-b), and Val-300 to Asn-319 of D2 (D2-a). These antibodies were then used in assays which were developed to structurally or functionally probe the potential Mn-binding regions of the D1 and D2 proteins.

  13. Characterization of the low-temperature triplet state of chlorophyll in photosystem II core complexes: Application of phosphorescence measurements and Fourier transform infrared spectroscopy.

    Science.gov (United States)

    Zabelin, Alexey A; Neverov, Konstantin V; Krasnovsky, Alexander A; Shkuropatova, Valentina A; Shuvalov, Vladimir A; Shkuropatov, Anatoly Ya

    2016-06-01

    Phosphorescence measurements at 77 K and light-induced FTIR difference spectroscopy at 95 K were applied to study of the triplet state of chlorophyll a ((3)Chl) in photosystem II (PSII) core complexes isolated from spinach. Using both methods, (3)Chl was observed in the core preparations with doubly reduced primary quinone acceptor QA. The spectral parameters of Chl phosphorescence resemble those in the isolated PSII reaction centers (RCs). The main spectral maximum and the lifetime of the phosphorescence corresponded to 955±1 nm and of 1.65±0.05 ms respectively; in the excitation spectrum, the absorption maxima of all core complex pigments (Chl, pheophytin a (Pheo), and β-carotene) were observed. The differential signal at 1667(-)/1628(+)cm(-1) reflecting a downshift of the stretching frequency of the 13(1)-keto C=O group of Chl was found to dominate in the triplet-minus-singlet FTIR difference spectrum of core complexes. Based on FTIR results and literature data, it is proposed that (3)Chl is mostly localized on the accessory chlorophyll that is in triplet equilibrium with P680. Analysis of the data suggests that the Chl triplet state responsible for the phosphorescence and the FTIR difference spectrum is mainly generated due to charge recombination in the reaction center radical pair P680(+)PheoD1(-), and the energy and temporal parameters of this triplet state as well as the molecular environment and interactions of the triplet-bearing Chl molecule are similar in the PSII core complexes and isolated PSII RCs. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. Characterisation of chlorophyll oxidation mediated by peroxidative activity in olives (Olea europaea L.) cv. Hojiblanca.

    Science.gov (United States)

    Vergara-Domínguez, Honorio; Roca, María; Gandul-Rojas, Beatriz

    2013-08-15

    The oxidation of chlorophyll a (chl a) catalysed by peroxidase (POD) from mesocarp of the olive fruit (Olea europaea L., cv Hojiblanca) in the presence of H2O2 and 2,4-dichlorophenol (2,4-DCP), is characterised via the individualised quantification of the products of the enzymatic reaction using a new methodology of HPLC-UV spectrometry. This innovation has allowed the discovery that, in addition to 13(2) OH chl a and 15(1) OH lactone chl a, which are the first products of POD on chl a, the reaction process sequentially creates another series of oxidised chlorophyll derivatives which have not been previously described. Their origins have been linked to POD activity in the presence of 2,4-DCP. Likewise, a study of the effect of the concentration of the various cosubstrates on the POD reaction rate demonstrated that the correct establishment of the relative concentrations of the same ([H2O2]/[2,4-DCP]/[Chl]=1:3:0.02) is crucial to explaining inhibition effects by substrates and carrying out optimum measurements. Therefore, new essential parameters for the determination of POD activity on a chlorophyll substrate are established. Copyright © 2013 Elsevier Ltd. All rights reserved.

  15. Crystal Structure and Catalytic Mechanism of 7-Hydroxymethyl Chlorophyll a Reductase*

    Science.gov (United States)

    Wang, Xiao; Liu, Lin

    2016-01-01

    7-Hydroxymethyl chlorophyll a reductase (HCAR) catalyzes the second half-reaction in chlorophyll b to chlorophyll a conversion. HCAR is required for the degradation of light-harvesting complexes and is necessary for efficient photosynthesis by balancing the chlorophyll a/b ratio. Reduction of the hydroxymethyl group uses redox cofactors [4Fe-4S] cluster and FAD to transfer electrons and is difficult because of the strong carbon-oxygen bond. Here, we report the crystal structure of Arabidopsis HCAR at 2.7-Å resolution and reveal that two [4Fe-4S]clusters and one FAD within a very short distance form a consecutive electron pathway to the substrate pocket. In vitro kinetic analysis confirms the ferredoxin-dependent electron transport chain, thus supporting a proton-activated electron transfer mechanism. HCAR resembles a partial reconstruction of an archaeal F420-reducing [NiFe] hydrogenase, which suggests a common mode of efficient proton-coupled electron transfer through conserved cofactor arrangements. Furthermore, the trimeric form of HCAR provides a biological clue of its interaction with light-harvesting complex II. PMID:27072131

  16. Synthesis of chlorophyll-c derivatives by modifying natural chlorophyll-a.

    Science.gov (United States)

    Xu, Meiyun; Kinoshita, Yusuke; Matsubara, Shogo; Tamiaki, Hitoshi

    2016-03-01

    Chlorophyll-a (Chl-a) was extracted from cyanobacterial cells and modified to methyl pyropheophorbide-a. The 3-vinyl-chlorin was transformed to zinc complex of the corresponding 3-acetyl-porphyrin. The zinc porphyrin was oxidized to give cis-7,8- and 17,18-dihydroxy-chlorins as well cis-7,8-cis-17,18-tetrahydroxybacteriochlorin. After zinc-demetallation, the isolated cis-7,8- and 17,18-diols were reduced at the 3-acetyl group and triply dehydrated under acidic conditions to afford two regioisomeric 3-vinyl-porphyrins, methyl divinyl-pyroprotopheophorbide-a possessing the 8-vinyl group and 17-propionate residue (one of the divinyl-protoChl-a derivatives) and methyl pyropheophorbide-c 1 possessing the 8-ethyl group and 17-acrylate residue (one of the Chl-c 1 derivatives), respectively. The resulting 7,8,17,18-tetrol was reduced and then acidically treated, giving five-fold dehydrated free base porphyrin, methyl pyropheophorbide-c 2 possessing the 3,8-divinyl groups and 17-acrylate residue (one of the Chl-c 2 derivatives). The visible absorption and fluorescence emission spectra of the three semi-synthetic 3-vinyl-porphyrins in dichloromethane were compared with those of the corresponding 8-ethyl-porphyrin bearing the 17-propionate residue, methyl pyroprotopheophorbide-a (one of the protoChl-a derivatives). The Soret and Qy absorption maxima were shifted to longer wavelengths with an increase of π-conjugation in a molecule: protoChl-a (8-CH2CH3/17-CH2CH2COOCH3) < divinyl-protoChl-a (8-CH=CH2/17-CH2CH2COOCH3) < Chl-c 1 (8-CH2CH3/17-CH=CHCOOCH3) < Chl-c 2 derivatives (8-CH=CH2/17-CH=CHCOOCH3). The 17(1),17(2)-dehydrogenation broadened the absorption bands. The emission maxima were bathochromically shifted in the same order. The reaction mechanism of the present dehydration indicates that the biosynthetic pathway of Chls-c would include the hydroxylation of the 17-propionate reside at the 17(1)-position and successive dehydration to the 17-acrylate residue.

  17. Salt stress change chlorophyll fluorescence in mango

    Directory of Open Access Journals (Sweden)

    Cicero Cartaxo de Lucena

    2012-12-01

    Full Text Available This study evaluated the tolerance of mango cultivars 'Haden', 'Palmer', 'Tommy Atkins' and 'Uba' grafted on rootstock 'Imbú' to salt stress using chlorophyll fluorescence. Plants were grown in modified Hoagland solution containing 0, 15, 30, and 45 mmol L-1 NaCl. At 97 days the parameters of the chlorophyll fluorescence (F0, Fm, Fv, F0/Fm, Fv/Fm, Fv'/Fm', ΦPSII = [(Fm'-Fs/(Fm'], D = (1- Fv'/Fm' and ETR = (ΦPSII×PPF×0,84×0,5 were determined. At 100 days, the leaf emission and leaf area, toxicity and leaf abscission indexes were determined. In all cultivars evaluated, in different degree, there were decreases in photochemical efficiency of photosystem II, enhanced concentrations from 15 mmol L-1 NaCl. The decreases in the potential quantum yield of photosystem II (Fv/Fm were 27.9, 18.7, 20.5, and 27.4%, for cultivars 'Haden', 'Palmer', 'Tommy Atkins', and 'Uba', respectively, when grown in 45 mmol L-1 NaCl. It was found decreases in leaf emission and mean leaf area in all cultivars from 15 mmol L-1 NaCl. There were increases in leaf toxicity of 33.0, 67.5, 41.6 and 80.8% and in leaf abscission of 71.8, 29.2, 32.5, and 67.9% for the cultivars 'Haden', 'Palmer', 'Tommy Atkins', and 'Uba' respectively, when grown in 45 mmol L-1 NaCl. Leaf toxicity and leaf abscission were not observed in 15 mmol L-1 NaCl. The decrease in Fv/Fm ratio were accompanied by decreasing in leaf emission and increased leaf toxicity index, showing, therefore, the potential of chlorophyll fluorescence in the early detection of salt stress in mango tree.

  18. An extended PROSPECT: Advance in the leaf optical properties model separating total chlorophylls into chlorophyll a and b.

    Science.gov (United States)

    Zhang, Yao; Huang, Jingfeng; Wang, Fumin; Blackburn, George Alan; Zhang, Hankui K; Wang, Xiuzhen; Wei, Chuanwen; Zhang, Kangyu; Wei, Chen

    2017-07-25

    The PROSPECT leaf optical model has, to date, well-separated the effects of total chlorophyll and carotenoids on leaf reflectance and transmittance in the 400-800 nm. Considering variations in chlorophyll a:b ratio with leaf age and physiological stress, a further separation of total plant-based chlorophylls into chlorophyll a and chlorophyll b is necessary for advanced monitoring of plant growth. In this study, we present an extended version of PROSPECT model (hereafter referred to as PROSPECT-MP) that can combine the effects of chlorophyll a, chlorophyll b and carotenoids on leaf directional hemispherical reflectance and transmittance (DHR and DHT) in the 400-800 nm. The LOPEX93 dataset was used to evaluate the capabilities of PROSPECT-MP for spectra modelling and pigment retrieval. The results show that PROSPECT-MP can both simultaneously retrieve leaf chlorophyll a and b, and also performs better than PROSPECT-5 in retrieving carotenoids concentrations. As for the simulation of DHR and DHT, the performances of PROSPECT-MP are similar to that of PROSPECT-5. This study demonstrates the potential of PROSPECT-MP for improving capabilities of remote sensing of leaf photosynthetic pigments (chlorophyll a, chlorophyll b and carotenoids) and for providing a framework for future refinements in the modelling of leaf optical properties.

  19. The Use of a Chlorophyll Meter (SPAD-502) for Field Determinations of Red Mangrove (Rhizophora Mangle L.) Leaf Chlorophyll Amount

    Science.gov (United States)

    Connelly, Xana M.

    1997-01-01

    The red mangrove Rhizophora mangle L., is a halophytic woody spermatophyte common to the land-sea interface of tropical and subtropical intertidal zones. It has been reported that 60 to 75% of the coastline of the earth's tropical regions are lined with mangroves. Mangroves help prevent shoreline erosion, provide breeding, nesting and feeding areas for many marine animals and birds. Mangroves are important contributors of primary production in the coastal environment, and this is largely proportional to the standing crop of leaf chlorophylls. Higher intensities of ultraviolet radiation, resulting from stratospheric ozone depletion, can lead to a reduction of chlorophyll in terrestrial plants. Since the most common method for determining chlorophyll concentration is by extraction and this is labor intensive and time consuming, few studies on photosynthetic pigments of mangroves have been reported. Chlorophyll meter readings have been related to leaf chlorophyll content in apples and maples. It has also been correlated to nitrogen status in corn and cotton. Peterson et al., (1993) used a chlorophyll meter to detect nitrogen deficiency in crops and in determining the need for additional nitrogen fertilizer. Efforts to correlate chlorophyll meter measurements to chlorophyll content of mangroves have not been reported. This paper describes the use of a hand-held chlorophyll meter (Minolta SPAD-502) to determine the amount of red mangrove foliar chlorophyll present in the field.

  20. The Magnesium Chelation Step in Chlorophyll Biosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Gregory L. Dilworth, Ph.D Chemical Sciences, Geosciences and Biosciences Division Office of Basis Energy Sciences, greg.dilworth@science.doe.gov

    2001-01-17

    The progress described in this report encompasses work supported by DOE grant DE-FG09-89ER13989 for the period 2/15/92 to the present 6/14/94. The goals of the project were to continue investigating the enzymology of Mg-chelatase and to investigate the co-regulation of heme and chlorophyll formation in intact plastids. During this period the laboratory had additional support (two years) from USDA to investigate heme metabolism in chloroplasts. This report is arranged so that the progress is described by reference to manuscripts which are published, under review or in preparation.

  1. Lil3 dimerization and chlorophyll binding in Arabidopsis thaliana.

    Science.gov (United States)

    Mork-Jansson, Astrid Elisabeth; Gargano, Daniela; Kmiec, Karol; Furnes, Clemens; Shevela, Dmitriy; Eichacker, Lutz Andreas

    2015-10-07

    The two-helix light harvesting like (Lil) protein Lil3 belongs to the family of chlorophyll binding light harvesting proteins of photosynthetic membranes. A function in tetrapyrrol synthesis and stabilization of geranylgeraniol reductase has been shown. Lil proteins contain the chlorophyll a/b-binding motif; however, binding of chlorophyll has not been demonstrated. We find that Lil3.2 from Arabidopsis thaliana forms heterodimers with Lil3.1 and binds chlorophyll. Lil3.2 heterodimerization (25±7.8 nM) is favored relative to homodimerization (431±59 nM). Interaction of Lil3.2 with chlorophyll a (231±49 nM) suggests that heterodimerization precedes binding of chlorophyll in Arabidopsis thaliana. Copyright © 2015 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

  2. Relationship of intertidal surface sediment chlorophyll concentration to hyper-spectral reflectance and chlorophyll fluorescence

    NARCIS (Netherlands)

    Kromkamp, J.C.; Morris, E.P.; Forster, R.M.; Honeywill, C.; Hagerthey, S.; Paterson, D.M.

    2006-01-01

    Estimating biomass of microphytobenthos (MPB) on intertidal mud flats is extremely difficult due to their patchy occurrence, especially at the scale of an entire mud flat. We tested two optical approaches that can be applied in situ: spectral reflectance and chlorophyll fluorescence. These two

  3. Chlorophyll-a specific volume scattering function of phytoplankton.

    Science.gov (United States)

    Tan, Hiroyuki; Oishi, Tomohiko; Tanaka, Akihiko; Doerffer, Roland; Tan, Yasuhiro

    2017-06-12

    Chlorophyll-a specific light volume scattering functions (VSFs) by cultured phytoplankton in visible spectrum range is presented. Chlorophyll-a specific VSFs were determined based on the linear least squares method using a measured VSFs with different chlorophyll-a concentrations. We found obvious variability of it in terms of spectral and angular shapes of VSF between cultures. It was also presented that chlorophyll-a specific scattering significantly affected on spectral variation of the remote sensing reflectance, depending on spectral shape of b. This result is useful for developing an advance algorithm of ocean color remote sensing and for deep understanding of light in the sea.

  4. Correlation of paramagnetic states and molecular structure in bacterial photosynthetic reaction centers: The symmetry of the primary electron donor in Rhodopseudomonas viridis and Rhodobacter sphaeroides R-26

    International Nuclear Information System (INIS)

    Norris, J.R.; Budil, D.E.; Gast, P.; Chang, C.H.; El-Kabbani, O.; Schiffer, M.

    1989-01-01

    The orientation of the principal axes of the primary electron donor triplet state measured in single crystals of photosynthetic reaction centers is compared to the x-ray structures of the bacteria Rhodobacter (Rb.) sphaeroides R-26 and Rhodopseudomonas (Rps.) viridis. The primary donor of Rps. viridis is significantly different from that of Rb. sphaeroides. The measured directions of the axes indicate that triplet excitation is almost completely localized on the L-subunit half of the dimer in Rps. viridis but is more symmetrically distributed on the dimeric donor in Rb. sphaeroides R-26. The large reduction of the zero field splitting parameters relative to monomeric bacteriochlorophyll triplet in vitro suggests significant participation of asymmetrical charge transfer electronic configurations in the special pair triplet state of both organisms

  5. Aborted germinal center reactions and B cell memory by follicular T cells specific for a B cell receptor V region peptide.

    Science.gov (United States)

    Heiser, Ryan A; Snyder, Christopher M; St Clair, James; Wysocki, Lawrence J

    2011-07-01

    A fundamental problem in immunoregulation is how CD4(+) T cells react to immunogenic peptides derived from the V region of the BCR that are created by somatic mechanisms, presented in MHC II, and amplified to abundance by B cell clonal expansion during immunity. BCR neo Ags open a potentially dangerous avenue of T cell help in violation of the principle of linked Ag recognition. To analyze this issue, we developed a murine adoptive transfer model using paired donor B cells and CD4 T cells specific for a BCR-derived peptide. BCR peptide-specific T cells aborted ongoing germinal center reactions and impeded the secondary immune response. Instead, they induced the B cells to differentiate into short-lived extrafollicular plasmablasts that secreted modest quantities of Ig. These results uncover an immunoregulatory process that restricts the memory pathway to B cells that communicate with CD4 T cells via exogenous foreign Ag.

  6. Stereoelectronic properties of aggregated chlorophyll systems

    Energy Technology Data Exchange (ETDEWEB)

    Christoffersen, R. E.; Maggiora, G. M.

    1979-09-01

    During the first nine months of the current contract, significant progress has occurred in several areas. All SCF CI studies of the singlet and triplet states of the neutral molecules Et-Chl a, Et-Pheo a, Et-BChl a, and Et-BPheo a, and the doublet states of the ..pi..-cation radicals Et-Chl a/sup +/. and Et-BChl a/sup +/. have now been completed. In addition, SCF CI calculations on BPheo a/sup -/. indicate that ..pi..-anion radicals can also be studied using the present approach. Similar work on a number of other ..pi..-cation and ..pi..-anion radicals is currently underway. Preliminary SCF CI studies have also been completed for benzoquinone and dihydroquinone, and studies on benzoquinone/sup -/. should be completed by the end of this year. The development and characterization of an empirical potential function is nearly complete, and data from selected systems is summarized. Implementation of a more efficient, quadratically convergent energy minimization procedure is also being carried out. This procedure should make it possible to study the geometry and properties of dimeric chlorophyll systems as well as various ligand-chlorophyll systems. Developmental work is continuing on the direct calculation of optical rotatory strengths.

  7. Biosynthesis of Chlorophyll a in a Purple Bacterial Phototroph and Assembly into a Plant Chlorophyll-Protein Complex.

    Science.gov (United States)

    Hitchcock, Andrew; Jackson, Philip J; Chidgey, Jack W; Dickman, Mark J; Hunter, C Neil; Canniffe, Daniel P

    2016-09-16

    Improvements to photosynthetic efficiency could be achieved by manipulating pigment biosynthetic pathways of photosynthetic organisms in order to increase the spectral coverage for light absorption. The development of organisms that can produce both bacteriochlorophylls and chlorophylls is one way to achieve this aim, and accordingly we have engineered the bacteriochlorophyll-utilizing anoxygenic phototroph Rhodobacter sphaeroides to make chlorophyll a. Bacteriochlorophyll and chlorophyll share a common biosynthetic pathway up to the precursor chlorophyllide. Deletion of genes responsible for the bacteriochlorophyll-specific modifications of chlorophyllide and replacement of the native bacteriochlorophyll synthase with a cyanobacterial chlorophyll synthase resulted in the production of chlorophyll a. This pigment could be assembled in vivo into the plant water-soluble chlorophyll protein, heterologously produced in Rhodobacter sphaeroides, which represents a proof-of-principle for the engineering of novel antenna complexes that enhance the spectral range of photosynthesis.

  8. Revisiting chlorophyll extraction methods in biological soil crusts - methodology for determination of chlorophyll a and chlorophyll a + b as compared to previous methods

    Science.gov (United States)

    Caesar, Jennifer; Tamm, Alexandra; Ruckteschler, Nina; Lena Leifke, Anna; Weber, Bettina

    2018-03-01

    Chlorophyll concentrations of biological soil crust (biocrust) samples are commonly determined to quantify the relevance of photosynthetically active organisms within these surface soil communities. Whereas chlorophyll extraction methods for freshwater algae and leaf tissues of vascular plants are well established, there is still some uncertainty regarding the optimal extraction method for biocrusts, where organism composition is highly variable and samples comprise major amounts of soil. In this study we analyzed the efficiency of two different chlorophyll extraction solvents, the effect of grinding the soil samples prior to the extraction procedure, and the impact of shaking as an intermediate step during extraction. The analyses were conducted on four different types of biocrusts. Our results show that for all biocrust types chlorophyll contents obtained with ethanol were significantly lower than those obtained using dimethyl sulfoxide (DMSO) as a solvent. Grinding of biocrust samples prior to analysis caused a highly significant decrease in chlorophyll content for green algal lichen- and cyanolichen-dominated biocrusts, and a tendency towards lower values for moss- and algae-dominated biocrusts. Shaking of the samples after each extraction step had a significant positive effect on the chlorophyll content of green algal lichen- and cyanolichen-dominated biocrusts. Based on our results we confirm a DMSO-based chlorophyll extraction method without grinding pretreatment and suggest the addition of an intermediate shaking step for complete chlorophyll extraction (see Supplement S6 for detailed manual). Determination of a universal chlorophyll extraction method for biocrusts is essential for the inter-comparability of publications conducted across all continents.

  9. Revisiting chlorophyll extraction methods in biological soil crusts – methodology for determination of chlorophyll a and chlorophyll a + b as compared to previous methods

    Directory of Open Access Journals (Sweden)

    J. Caesar

    2018-03-01

    Full Text Available Chlorophyll concentrations of biological soil crust (biocrust samples are commonly determined to quantify the relevance of photosynthetically active organisms within these surface soil communities. Whereas chlorophyll extraction methods for freshwater algae and leaf tissues of vascular plants are well established, there is still some uncertainty regarding the optimal extraction method for biocrusts, where organism composition is highly variable and samples comprise major amounts of soil. In this study we analyzed the efficiency of two different chlorophyll extraction solvents, the effect of grinding the soil samples prior to the extraction procedure, and the impact of shaking as an intermediate step during extraction. The analyses were conducted on four different types of biocrusts. Our results show that for all biocrust types chlorophyll contents obtained with ethanol were significantly lower than those obtained using dimethyl sulfoxide (DMSO as a solvent. Grinding of biocrust samples prior to analysis caused a highly significant decrease in chlorophyll content for green algal lichen- and cyanolichen-dominated biocrusts, and a tendency towards lower values for moss- and algae-dominated biocrusts. Shaking of the samples after each extraction step had a significant positive effect on the chlorophyll content of green algal lichen- and cyanolichen-dominated biocrusts. Based on our results we confirm a DMSO-based chlorophyll extraction method without grinding pretreatment and suggest the addition of an intermediate shaking step for complete chlorophyll extraction (see Supplement S6 for detailed manual. Determination of a universal chlorophyll extraction method for biocrusts is essential for the inter-comparability of publications conducted across all continents.

  10. Orientations of Iron-Sulfur Clusters FA and FB in the Homodimeric Type-I Photosynthetic Reaction Center of Heliobacterium modesticaldum.

    Science.gov (United States)

    Kondo, Toru; Matsuoka, Masahiro; Azai, Chihiro; Itoh, Shigeru; Oh-Oka, Hirozo

    2016-05-12

    Orientations of the FA and FB iron-sulfur (FeS) clusters in a structure-unknown type-I homodimeric heriobacterial reaction center (hRC) were studied in oriented membranes of the thermophilic anaerobic photosynthetic bacterium Heliobacterium modesticaldum by electron paramagnetic resonance (EPR), and compared with those in heterodimeric photosystem I (PS I). The Rieske-type FeS center in the cytochrome b/c complex showed a well-oriented EPR signal. Illumination at 14 K induced an FB(-) signal with g-axes of gz = 2.066, gy = 1.937, and gx = 1.890, tilted at angles of 60°, 60°, and 45°, respectively, with respect to the membrane normal. Chemical reduction with dithionite produced an additional signal of FA(-), which magnetically interacted with FB(-), with gz = 2.046, gy = 1.942, and gx = 1.911 at 30°, 60°, and 90°, respectively. The angles and redox properties of FA(-) and FB(-) in hRC resemble those of FB(-) and FA(-), respectively, in PS I. Therefore, FA and FB in hRC, named after their g-value similarities, seem to be located like FB and FA, not like FA and FB, respectively, in PS I. The reducing side of hRC could resemble those in PS I, if the names of FA and FB are interchanged with each other.

  11. Cytochrome P450 CYP89A9 Is Involved in the Formation of Major Chlorophyll Catabolites during Leaf Senescence in Arabidopsis[W][OA

    Science.gov (United States)

    Christ, Bastien; Süssenbacher, Iris; Moser, Simone; Bichsel, Nicole; Egert, Aurelie; Müller, Thomas; Hörtensteiner, Stefan

    2013-01-01

    Nonfluorescent chlorophyll catabolites (NCCs) were described as products of chlorophyll breakdown in Arabidopsis thaliana. NCCs are formyloxobilin-type catabolites derived from chlorophyll by oxygenolytic opening of the chlorin macrocycle. These linear tetrapyrroles are generated from their fluorescent chlorophyll catabolite (FCC) precursors by a nonenzymatic isomerization inside the vacuole of senescing cells. Here, we identified a group of distinct dioxobilin-type chlorophyll catabolites (DCCs) as the major breakdown products in wild-type Arabidopsis, representing more than 90% of the chlorophyll of green leaves. The molecular constitution of the most abundant nonfluorescent DCC (NDCC), At-NDCC-1, was determined. We further identified cytochrome P450 monooxygenase CYP89A9 as being responsible for NDCC accumulation in wild-type Arabidopsis; cyp89a9 mutants that are deficient in CYP89A9 function were devoid of NDCCs but accumulated proportionally higher amounts of NCCs. CYP89A9 localized outside the chloroplasts, implying that FCCs occurring in the cytosol might be its natural substrate. Using recombinant CYP89A9, we confirm FCC specificity and show that fluorescent DCCs are the products of the CYP89A9 reaction. Fluorescent DCCs, formed by this enzyme, isomerize to the respective NDCCs in weakly acidic medium, as found in vacuoles. We conclude that CYP89A9 is involved in the formation of dioxobilin-type catabolites of chlorophyll in Arabidopsis. PMID:23723324

  12. Unifying principles in homodimeric type I photosynthetic reaction centers: properties of PscB and the FA, FB and FX iron-sulfur clusters in green sulfur bacteria.

    Science.gov (United States)

    Jagannathan, Bharat; Golbeck, John H

    2008-12-01

    The photosynthetic reaction center from the green sulfur bacterium Chlorobium tepidum (CbRC) was solubilized from membranes using Triton X-100 and isolated by sucrose density ultra-centrifugation. The CbRC complexes were subsequently treated with 0.5 M NaCl and ultrafiltered over a 100 kDa cutoff membrane. The resulting CbRC cores did not exhibit the low-temperature EPR resonances from FA- and FB- and were unable to reduce NADP+. SDS-PAGE and mass spectrometric analysis showed that the PscB subunit, which harbors the FA and FB clusters, had become dissociated, and was now present in the filtrate. Attempts to rebind PscB onto CbRC cores were unsuccessful. Mössbauer spectroscopy showed that recombinant PscB contains a heterogeneous mixture of [4Fe-4S]2+,1+ and other types of Fe/S clusters tentatively identified as [2Fe-2S]2+,1+ clusters and rubredoxin-like Fe3+,2+ centers, and that the [4Fe-4S]2+,1+ clusters which were present were degraded at high ionic strength. Quantitative analysis confirmed that the amount of iron and sulfide in the recombinant protein was sub-stoichiometric. A heme-staining assay indicated that cytochrome c551 remained firmly attached to the CbRC cores. Low-temperature EPR spectroscopy of photoaccumulated CbRC complexes and CbRC cores showed resonances between g=5.4 and 4.4 assigned to a S=3/2 ground spin state [4Fe-4S]1+ cluster and at g=1.77 assigned to a S=1/2 ground spin state [4Fe-4S]1+ cluster, both from FX-. These results unify the properties of the acceptor side of the Type I homodimeric reaction centers found in green sulfur bacteria and heliobacteria: in both, the FA and FB iron-sulfur clusters are present on a salt-dissociable subunit, and FX is present as an interpolypeptide [4Fe-4S]2+,1+ cluster with a significant population in a S=3/2 ground spin state.

  13. An optimal thermal condition for maximal chlorophyll extraction

    Directory of Open Access Journals (Sweden)

    Fu Jia-Jia

    2017-01-01

    Full Text Available This work describes an environmentally friendly process for chlorophyll extraction from bamboo leaves. Shaking water bath and ultrasound cleaner are adopted in this technology, and the influence of temperature of the water bath and ultrasonic cleaner is evaluated. Results indicated that there is an optimal condition for maximal yield of chlorophyll.

  14. Regional ocean-colour chlorophyll algorithms for the Red Sea

    KAUST Repository

    Brewin, Robert J.W.; Raitsos, Dionysios E.; Dall'Olmo, Giorgio; Zarokanellos, Nikolaos; Jackson, Thomas; Racault, Marie-Fanny; Boss, Emmanuel S.; Sathyendranath, Shubha; Jones, Burton; Hoteit, Ibrahim

    2015-01-01

    an ocean-colour model for the Red Sea, parameterised to data collected during the Tara Oceans expedition, that estimates remote-sensing reflectance as a function of chlorophyll concentration. We used the Red Sea model to tune the standard chlorophyll

  15. Chlorophyll in tomato seeds: marker for seed performance?

    NARCIS (Netherlands)

    Suhartanto, M.R.

    2002-01-01

    Using Xe-PAM, laser induced fluorometry and high performance liquid chromatography we found that chlorophyll was present in young tomato (cv. Moneymaker) seeds and was degraded during maturation. Fluorescence microscopy and imaging showed that the majority of chlorophyll is located in the

  16. A model for chlorophyll fluorescence and photosynthesis at leaf scale

    NARCIS (Netherlands)

    Tol, van der C.; Verhoef, W.; Rosema, A.

    2009-01-01

    This paper presents a leaf biochemical model for steady-state chlorophyll fluorescence and photosynthesis of C3 and C4 vegetation. The model is a tool to study the relationship between passively measured steady-state chlorophyll fluorescence and actual photosynthesis, and its evolution during the

  17. Chlorophyll meter reading and total nitrogen content applied as ...

    African Journals Online (AJOL)

    Ana Mascarello

    The present study was aimed to assess the relationship between the reading of the chlorophyll meter and the total nitrogen (N) content ... devices to measure chlorophyll index (SPAD) and N content in the leaf. The nitrogen levels were found ... absorption of other nutrients and the production of carbohydrates. The methods ...

  18. Dinitrogen fixation in a unicellular chlorophyll d-containing cyanobacterium

    NARCIS (Netherlands)

    Pfreundt, U.; Stal, L.J.; Voss, B.; Hess, W.R.

    2012-01-01

    Marine cyanobacteria of the genus Acaryochloris are the only known organisms that use chlorophyll d as a photosynthetic pigment. However, based on chemical sediment analyses, chlorophyll d has been recognized to be widespread in oceanic and lacustrine environments. Therefore it is highly relevant to

  19. Influence of ambient sulphur dioxide on chlorophyll

    International Nuclear Information System (INIS)

    Shahare, C.B.; Varshney, C.K.

    1995-01-01

    For the evaluation of the injury due to SO 2 from Indraprashtha (IP) Thermal Power Plant, eight species of trees were selected. Experiment was divided in two sections. Section one include transplanted tree saplings of Bauhinia variegata, Delonix regia, Flcus benghalensis, Putranjiwa roxburghii, Morus indica, Polyalthia longifolia, Leucaena leucocephala and Tabernaemontana coronaria. Here one set of plants was transplanted to polluted site of IP and other set was maintained at non polluted site of Jawaharlal Nehru University (Ecological Nursery). Second section of the study have naturally growing trees of the same species in the vicinity of the transplanted plants. Findings of the present study show that tree species were not safe at polluted site. Maximum chlorophyll reduction occurred in Bauhinia variegata, that is 32.05% (transplanted saplings). In naturally growing trees up to 35.70% reduction was seen in B. variegata. (author). 11 refs., 2 tabs

  20. Phytohormone and Light Regulation of Chlorophyll Degradation

    Directory of Open Access Journals (Sweden)

    Xiaoyu Zhu

    2017-11-01

    Full Text Available Degreening, due to the net loss of chlorophyll (Chl, is the most prominent symptom during the processes of leaf senescence, fruit ripening, and seed maturation. Over the last decade or so, extensive identifications of Chl catabolic genes (CCGs have led to the revelation of the biochemical pathway of Chl degradation. As such, exploration of the regulatory mechanism of the degreening process is greatly facilitated. During the past few years, substantial progress has been made in elucidating the regulation of Chl degradation, particularly via the mediation of major phytohormones' signaling. Intriguingly, ethylene and abscisic acid's signaling have been demonstrated to interweave with light signaling in mediating the regulation of Chl degradation. In this review, we briefly summarize this progress, with an effort on providing a framework for further investigation of multifaceted and hierarchical regulations of Chl degradation.

  1. A new three-band algorithm for estimating chlorophyll concentrations in turbid inland lakes

    International Nuclear Information System (INIS)

    Duan Hongtao; Ma Ronghua; Zhao Chenlu; Zhou Lin; Shang Linlin; Zhang Yuanzhi; Loiselle, Steven Arthur; Xu Jingping

    2010-01-01

    A new three-band model was developed to estimate chlorophyll-a concentrations in turbid inland waters. This model makes a number of important improvements with respect to the three-band model commonly used, including lower restrictions on wavelength optimization and the use of coefficients which represent specific inherent optical properties. Results showed that the new model provides a significantly higher determination coefficient and lower root mean squared error (RMSE) with respect to the original model for upwelling data from Taihu Lake, China. The new model was tested using simulated data for the MERIS and GOCI satellite systems, showing high correlations with the former and poorer correlations with the latter, principally due to the lack of a 709 nm centered waveband. The new model provides numerous advantages, making it a suitable alternative for chlorophyll-a estimations in turbid and eutrophic waters.

  2. Xanthophyll cycle-dependent quenching of photosystem II chlorophyll a fluorescence: Formation of a quenching complex with a short fluorescence lifetime

    Energy Technology Data Exchange (ETDEWEB)

    Gilmore, A.M.; Hazlett, T.L.; Govindjee [Univ. of Illinois, Urbana, IL (United States)

    1995-03-14

    Excess light triggers protective nonradiative dissipation of excitation energy in photosystem II through the formation of a trans-thylakoid pH gradient that in turn stimulates formation of zeaxanthin and antheraxanthin. These xanthophylls when combined with protonation of antenna pigment-protein complexes may increase nonradiative dissipation and, thus, quench chlorophyll a fluorescence. Here we measured, in parallel, the chlorophyll a fluorescence lifetime and intensity to understand the mechanism of this process. Increasing the xanthophyll concentration in the presence of a pH gradient (quenched conditions) decreases the fractional intensity of a fluorescence lifetime component centered at {approx}2 ns and increases a component at {approx}0.4 ns. Uncoupling the pH gradient (unquenched conditions) eliminates the 0.4-ns component. Changes in the xanthophyll concentration do not significantly affect the fluorescence lifetimes in either the quenched or unquenched sample conditions. However, there are differences in fluorescence lifetimes between the quenched and unquenched states that are due to pH-related, but nonxanthophyll-related, processes. Quenching of the maximal fluorescence intensity correlates with both the xanthophyll concentration and the fractional intensity of the 0.4-ns component. The unchanged fluorescence lifetimes and the proportional quenching of the maximal and dark-level fluorescence intensities indicate that the xanthophyllact on antenna, not reaction center processes. Further, the fluorescence quenching is interpreted as the combined effect of the pH gradient and xanthophyll concentration, resulting in the formation of a quenching complex with a short ({approx}0.4 ns) fluorescence lifetime. 33 refs., 6 figs., 2 tabs.

  3. The magnesium chelation step in chlorophyll biosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Weinstein, J.

    1990-11-01

    In photosynthetic organisms, the biogenesis of energy transducing membranes requires the coordinate synthesis of prosthetic groups, proteins, and various lipids. Two of the major prosthetic groups, chlorophyll and heme, share a common biosynthetic pathway that diverges at the point of metal insertion into protoporphyrin IX (Proto). Insertion of iron leads to the formation of hemes, while insertion of magnesium is the first step unique to chlorophyll formation. This project is directed toward identifying the enzyme(s) responsible for magnesium chelation and elucidating the mechanism which regulates the flux of precursors through the branch point enzymes in isolated chloroplasts. Using intact chloroplasts from greening cucumber cotyledons, we have confirmed the ATP requirement for Mg-Proto formation. Use of non-hydrolyzable ATP analogs, uncouplers and ionophores has led to the conclusions that ATP hydrolysis is necessary, but that this hydrolysis is not linked to the requirement for membrane intactness by transmembrane ion gradients or electrical potentials. The enzyme(s) are flexible with respect to the porphyrin substrate specificity, accepting porphyrins with -vinyl, -ethyl, or -H substituents at the 2 and 4 positions. The activity increases approximately four-fold during greening. Possible physiological feedback inhibitors such as heme, protochlorophyllide, and chlorophyllide had no specific effect on the activity. The activity has now been assayed in barely, corn and peas, with the system from peas almost ten-fold more active than the cucumber system. Work is continuing in pea chloroplasts with the development of a continuous assay and investigation of the feasibility of characterizing an active, organelle-free preparation. 6 figs.

  4. Chlorophyll loss associated with heat-induced senescence in bentgrass.

    Science.gov (United States)

    Jespersen, David; Zhang, Jing; Huang, Bingru

    2016-08-01

    Heat stress-induced leaf senescence is characterized by the loss of chlorophyll from leaf tissues. The objectives of this study were to examine genetic variations in the level of heat-induced leaf senescence in hybrids of colonial (Agrostis capillaris)×creeping bentgrass (Agrostis stolonifera) contrasting in heat tolerance, and determine whether loss of leaf chlorophyll during heat-induced leaf senescence was due to suppressed chlorophyll synthesis and/or accelerated chlorophyll degradation in the cool-season perennial grass species. Plants of two hybrid backcross genotypes ('ColxCB169' and 'ColxCB190') were exposed to heat stress (38/33°C, day/night) for 28 d in growth chambers. The analysis of turf quality, membrane stability, photochemical efficiency, and chlorophyll content demonstrated significant variations in the level of leaf senescence induced by heat stress between the two genotypes, with ColXCB169 exhibiting a lesser degree of decline in chlorophyll content, photochemical efficiency and membrane stability than ColXCB190. The assays of enzymatic activity or gene expression of several major chlorophyll-synthesizing (porphobilinogen deaminase, Mg-chelatase, protochlorophyllide-reductase) and chlorophyll-degrading enzymes (chlorophyllase, pheophytinase, and chlorophyll-degrading peroxidase) indicated heat-induced decline in leaf chlorophyll content was mainly due to accelerated chlorophyll degradation, as manifested by increased gene expression levels of chlorophyllase and pheophytinase, and the activity of pheophytinase (PPH), while chlorophyll-synthesizing genes and enzymatic activities were not differentially altered by heat stress in the two genotypes. The analysis of heat-induced leaf senescence of pph mutants of Arabidopsis further confirmed that PPH could be one enzymes that plays key roles in regulating heat-accelerated chlorophyll degradation. Further research on enzymes responsible in part for the loss of chlorophyll during heat

  5. Physiological responses of Brassica napus to fulvic acid under water stress: Chlorophyll a fluorescence and antioxidant enzyme activity

    Directory of Open Access Journals (Sweden)

    Ramin Lotfi

    2015-10-01

    Full Text Available The ameliorative effect of fulvic acid (0, 300, and 600 mg L− 1 on photosystem II and antioxidant enzyme activity of the rapeseed (Brassica napus L. plant under water stress (60, 100, and 140 mm evaporation from class A pan was studied using split plots in a randomized complete block design with three replications. Results indicated that application of fulvic acid (FA improved the maximum quantum efficiency of PSII (Fv/Fm and performance index (PI of plants under both well-watered and limited-water conditions. The time span from Fo to Fm and the energy necessary for the closure of all reaction centers was significantly increased, but the size of the plastoquinone pool was reduced with increasing water stress levels. Plants treated with FA had higher peroxidase and catalase activities under all irrigation conditions. Activities of ascorbate peroxidase and superoxide dismutase in plants increased with increasing water stress. Malondialdehyde increased under severe water stress, but application of FA significantly decreased lipid peroxidation. Production of reactive oxygen species (ROS is a common phenomenon in plants under stress. Under this condition, the balance between the production of ROS and the quenching activity of antioxidants is upset, often resulting in oxidative damage. In this study, application of FA significantly increased fluorescence of chlorophyll a, inhibiting ROS production and enhancing antioxidant enzymes activity that destroyed ROS. Thus, ROS in plant cells was reduced under water stress by application of FA and consequently lipid peroxidation was reduced.

  6. Ultrasonic selectivity on depressing photosynthesis of cyanobacteria and green algae probed by chlorophyll-a fluorescence transient.

    Science.gov (United States)

    Duan, Zhipeng; Tan, Xiao; Li, Niegui

    2017-10-01

    Ultrasound can inhibit cyanobacterial growth through rupturing cells, but this pathway frequently has the risk to release intercellular toxin (e.g., microcystin). Depressing photosynthesis without cell disruption may provide a new strategy to control cyanobacterial blooms using ultrasound, especially Microcystis blooms. In this work, Microcystis aeruginosa (toxic cyanobacteria) and Chlorella pyrenoidosa (typical green algae) were chosen as model microalgae to verify this hypothesis. Results showed that ultrasound has the ability to inhibit cyanobacterial photosynthesis significantly and selectively. Specifically, sonication damaged Q A , a tightly bound one-electron acceptor, and blocked electron flow at Q B , a two-electron acceptor, in the photosystem II (PSII) of M. aeruginosa when it was exposed for 60 s (35 kHz, 0.043 W/cm 3 ). Moreover, 44.8% of the reaction centers (RCs) in the PSII of M. aeruginosa were transferred into inactive ones (RC si s), and the cell concentration decreased by 32.5% after sonication for 300 s. By contrast, only 7.9% of RC si occurred in C. pyrenoidosa, and cell concentration and chlorophyll-a content reduced by 18.7% and 9.3%, respectively. Differences in both species (i.e., cell structures) might be responsible for the varying levels to sonication. This research suggests that cyanobacteria, especially Microcystis, could be controlled by ultrasound via damaging their PSIIs.

  7. Calibrations between chlorophyll meter values and chlorophyll contents vary as the result of differences in leaf structure

    Science.gov (United States)

    In order to relate leaf chlorophyll meter values with total leaf chlorophyll contents (µg cm-2), calibration equations are established with measured data on leaves. Many studies have documented differences in calibration equations using different species and using different growing conditions for th...

  8. The AtCAO gene, encoding chlorophyll a oxygenase, is required for chlorophyll b synthesis in Arabidopsis thaliana

    Science.gov (United States)

    Espineda, Cromwell E.; Linford, Alicia S.; Devine, Domenica; Brusslan, Judy A.

    1999-01-01

    Chlorophyll b is synthesized from chlorophyll a and is found in the light-harvesting complexes of prochlorophytes, green algae, and both nonvascular and vascular plants. We have used conserved motifs from the chlorophyll a oxygenase (CAO) gene from Chlamydomonas reinhardtii to isolate a homologue from Arabidopsis thaliana. This gene, AtCAO, is mutated in both leaky and null chlorina1 alleles, and DNA sequence changes cosegregate with the mutant phenotype. AtCAO mRNA levels are higher in three different mutants that have reduced levels of chlorophyll b, suggesting that plants that do not have sufficient chlorophyll b up-regulate AtCAO gene expression. Additionally, AtCAO mRNA levels decrease in plants that are grown under dim-light conditions. We have also found that the six major Lhcb proteins do not accumulate in the null ch1-3 allele. PMID:10468639

  9. Aromatic residues located close to the active center are essential for the catalytic reaction of flap endonuclease-1 from hyperthermophilic archaeon Pyrococcus horikoshii.

    Science.gov (United States)

    Matsui, Eriko; Abe, Junko; Yokoyama, Hideshi; Matsui, Ikuo

    2004-04-16

    Flap endonuclease-1 (FEN-1) possessing 5'-flap endonuclease and 5'-->3' exonuclease activity plays important roles in DNA replication and repair. In this study, the kinetic parameters of mutants at highly conserved aromatic residues, Tyr33, Phe35, Phe79, and Phe278-Phe279, in the vicinity of the catalytic centers of FEN-1 were examined. The substitution of these aromatic residues with alanine led to a large reduction in kcat values, although these mutants retained Km values similar to that of the wild-type enzyme. Notably, the kcat of Y33A and F79A decreased 333-fold and 71-fold, respectively, compared with that of the wild-type enzyme. The aromatic residues Tyr33 and Phe79, and the aromatic cluster Phe278-Phe279 mainly contributed to the recognition of the substrates without the 3' projection of the upstream strand (the nick, 5'-recess-end, single-flap, and pseudo-Y substrates) for the both exo- and endo-activities, but played minor roles in recognizing the substrates with the 3' projection (the double flap substrate and the nick substrate with the 3' projection). The replacement of Tyr33, Phe79, and Phe278-Phe279, with non-charged aromatic residues, but not with aliphatic hydrophobic residues, recovered the kcat values almost fully for the substrates without the 3' projection of the upstream strand, suggesting that the aromatic groups of Tyr33, Phe79, and Phe278-Phe279 might be involved in the catalytic reaction, probably via multiple stacking interactions with nucleotide bases. The stacking interactions of Tyr33 and Phe79 might play important roles in fixing the template strand and the downstream strand, respectively, in close proximity to the active center to achieve the productive transient state leading to the hydrolysis.

  10. Role of Rhodobacter sphaeroides photosynthetic reaction center residue M214 in the composition, absorbance properties, and conformations of H(A) and B(A) cofactors.

    Science.gov (United States)

    Saer, Rafael G; Hardjasa, Amelia; Rosell, Federico I; Mauk, A Grant; Murphy, Michael E P; Beatty, J Thomas

    2013-04-02

    In the native reaction center (RC) of Rhodobacter sphaeroides, the side chain of (M)L214 projects orthogonally toward the plane and into the center of the A branch bacteriopheophytin (BPhe) macrocycle. The possibility that this side chain is responsible for the dechelation of the central Mg(2+) of bacteriochlorophyll (BChl) was investigated by replacement of (M)214 with residues possessing small, nonpolar side chains that can neither coordinate nor block access to the central metal ion. The (M)L214 side chain was also replaced with Cys, Gln, and Asn to evaluate further the requirements for assembly of the RC with BChl in the HA pocket. Photoheterotrophic growth studies showed no difference in growth rates of the (M)214 nonpolar mutants at a low light intensity, but the growth of the amide-containing mutants was impaired. The absorbance spectra of purified RCs indicated that although absorbance changes are associated with the nonpolar mutations, the nonpolar mutant RC pigment compositions are the same as in the wild-type protein. Crystal structures of the (M)L214G, (M)L214A, and (M)L214N mutants were determined (determined to 2.2-2.85 Å resolution), confirming the presence of BPhe in the HA pocket and revealing alternative conformations of the phytyl tail of the accessory BChl in the BA site of these nonpolar mutants. Our results demonstrate that (i) BChl is converted to BPhe in a manner independent of the aliphatic side chain length of nonpolar residues replacing (M)214, (ii) BChl replaces BPhe if residue (M)214 has an amide-bearing side chain, (iii) (M)214 side chains containing sulfur are not sufficient to bind BChl in the HA pocket, and (iv) the (M)214 side chain influences the conformation of the phytyl tail of the BA BChl.

  11. Pattern of Adverse Drug Reactions in Children Attending the Department of Pediatrics in a Tertiary Care Center: A Prospective Observational Study

    Directory of Open Access Journals (Sweden)

    Kishour Kumar Digra

    2015-01-01

    Full Text Available AIM To study the pattern of various adverse drug reactions (ADRs occurring in children attending the Department of Pediatrics, SMGS Hospital, Jammu over 1 year. Subjects and Methods This was a prospective study, with study population of patients attending Department of Pediatrics over a period of 1 year. A structured format was used to enroll the participants. A pilot study was conducted to test the suitability of the format and feasibility of the study. The study was carried out to review various pattern of ADRs by using the Naranjo probability scale, and severity was assessed by using the Hartwig severity scale. ADRs were classified according to the classification used by the Adverse Drug Reaction Monitoring Center, Central Drugs Standard Control Organization, New Delhi, India. Results In the present study, 104 patients were found to have developed acute drug reactions. Among these, 83.6% were type B, 14.42% type A, and 1.92% were type U. Furthermore, 25.96% ADRs were due to anticonvulsants, followed by antibiotics (22.11%, antipyretics (11.53%, vaccination (8.65%, steroids (6.73%, decongestants (5.67%, snake antivenom and antiemetics (3.84%, and fluids, insulin, and antacids (1.92%. The patients’ dermatological system was involved in 67.30%, followed by the central nervous system (CNS in 11.53% patients. Renal system was involved in 6.73% patients. Cardiac, musculoskeletal, metabolic, and other systems were involved in 4.80%, 3.84%, 2.88%, and 0.96%, respectively. According to the Hartwig severity scale of ADRs, 64.4% patients had moderate ADRs, 29.8% patients had severe ADRs, and 5.76% had mild ADRs. In the present study, 64.4% patients expressed moderate severity, whereas 29.8% expressed high severity and 5.76% expressed mild ADRs. Conclusion ADRs were seen in 71% of the patients between 1 and 5 years of age, 26% in the age group of 5–10 years, and 3% were more than 10 years old. Anticonvulsants (25.96% and antibiotics (22.11% were

  12. Optical Method for Estimating the Chlorophyll Contents in Plant Leaves.

    Science.gov (United States)

    Pérez-Patricio, Madaín; Camas-Anzueto, Jorge Luis; Sanchez-Alegría, Avisaí; Aguilar-González, Abiel; Gutiérrez-Miceli, Federico; Escobar-Gómez, Elías; Voisin, Yvon; Rios-Rojas, Carlos; Grajales-Coutiño, Ruben

    2018-02-22

    This work introduces a new vision-based approach for estimating chlorophyll contents in a plant leaf using reflectance and transmittance as base parameters. Images of the top and underside of the leaf are captured. To estimate the base parameters (reflectance/transmittance), a novel optical arrangement is proposed. The chlorophyll content is then estimated by using linear regression where the inputs are the reflectance and transmittance of the leaf. Performance of the proposed method for chlorophyll content estimation was compared with a spectrophotometer and a Soil Plant Analysis Development (SPAD) meter. Chlorophyll content estimation was realized for Lactuca sativa L., Azadirachta indica , Canavalia ensiforme , and Lycopersicon esculentum . Experimental results showed that-in terms of accuracy and processing speed-the proposed algorithm outperformed many of the previous vision-based approach methods that have used SPAD as a reference device. On the other hand, the accuracy reached is 91% for crops such as Azadirachta indica , where the chlorophyll value was obtained using the spectrophotometer. Additionally, it was possible to achieve an estimation of the chlorophyll content in the leaf every 200 ms with a low-cost camera and a simple optical arrangement. This non-destructive method increased accuracy in the chlorophyll content estimation by using an optical arrangement that yielded both the reflectance and transmittance information, while the required hardware is cheap.

  13. Effects of biocides on chlorophyll contents of detached basil leaves

    Directory of Open Access Journals (Sweden)

    Titima Arunrangsi

    2013-06-01

    Full Text Available Herbicides and insecticides have been widely and intensively used in agricultural areas worldwide to enhance crop yield. However, many biocides cause serious environmental problems. In addition, the biocides may also have some effects on the treated agricultural crops. To study effects of biocides on chlorophyll content in detached basil leaves, 2,4-D dimethylamine salt (2,4 D-Amine, paraquat, carbosulfan, and azadirachtin, were chosen as representatives of biocide. After applying the chemicals to detached basil leaves overnight in darkness, chlorophyll contents were determined. Only treatment with 2,4 D-Amine resulted in reduction of chlorophyll contents significantly compared to treatment with deionized (DI water. In the case of paraquat and carbosulfan, chlorophyll contents were not significantly changed, while slightly higher chlorophyll contents, compared to DI water, after the treatment with azadirachtin, were observed. The results indicated that 2,4 D-Amine shows an ability to accelerate chlorophyll degradation, but azadirachtin helps to retard chlorophyll degradation, when each biocide is used at the concentration recommended by the manufacturer.

  14. Optical Method for Estimating the Chlorophyll Contents in Plant Leaves

    Directory of Open Access Journals (Sweden)

    Madaín Pérez-Patricio

    2018-02-01

    Full Text Available This work introduces a new vision-based approach for estimating chlorophyll contents in a plant leaf using reflectance and transmittance as base parameters. Images of the top and underside of the leaf are captured. To estimate the base parameters (reflectance/transmittance, a novel optical arrangement is proposed. The chlorophyll content is then estimated by using linear regression where the inputs are the reflectance and transmittance of the leaf. Performance of the proposed method for chlorophyll content estimation was compared with a spectrophotometer and a Soil Plant Analysis Development (SPAD meter. Chlorophyll content estimation was realized for Lactuca sativa L., Azadirachta indica, Canavalia ensiforme, and Lycopersicon esculentum. Experimental results showed that—in terms of accuracy and processing speed—the proposed algorithm outperformed many of the previous vision-based approach methods that have used SPAD as a reference device. On the other hand, the accuracy reached is 91% for crops such as Azadirachta indica, where the chlorophyll value was obtained using the spectrophotometer. Additionally, it was possible to achieve an estimation of the chlorophyll content in the leaf every 200 ms with a low-cost camera and a simple optical arrangement. This non-destructive method increased accuracy in the chlorophyll content estimation by using an optical arrangement that yielded both the reflectance and transmittance information, while the required hardware is cheap.

  15. Transcriptome Analysis of Manganese-deficient Chlamydomonas reinhardtii Provides Insight on the Chlorophyll Biosynthesis Pathway

    Energy Technology Data Exchange (ETDEWEB)

    Lockhart, Ainsley; Zvenigorodsky, Natasha; Pedraza, Mary Ann; Lindquist, Erika

    2011-08-11

    The biosynthesis of chlorophyll and other tetrapyrroles is a vital but poorly understood process. Recent genomic advances with the unicellular green algae Chlamydomonas reinhardtii have created opportunity to more closely examine the mechanisms of the chlorophyll biosynthesis pathway via transcriptome analysis. Manganese is a nutrient of interest for complex reactions because of its multiple stable oxidation states and role in molecular oxygen coordination. C. reinhardtii was cultured in Manganese-deplete Tris-acetate-phosphate (TAP) media for 24 hours and used to create cDNA libraries for sequencing using Illumina TruSeq technology. Transcriptome analysis provided intriguing insight on possible regulatory mechanisms in the pathway. Evidence supports similarities of GTR (Glutamyl-tRNA synthase) to its Chlorella vulgaris homolog in terms of Mn requirements. Data was also suggestive of Mn-related compensatory up-regulation for pathway proteins CHLH1 (Manganese Chelatase), GUN4 (Magnesium chelatase activating protein), and POR1 (Light-dependent protochlorophyllide reductase). Intriguingly, data suggests possible reciprocal expression of oxygen dependent CPX1 (coproporphyrinogen III oxidase) and oxygen independent CPX2. Further analysis using RT-PCR could provide compelling evidence for several novel regulatory mechanisms in the chlorophyll biosynthesis pathway.

  16. Charge stabilization by reaction center protein immobilized to carbon nanotubes functionalized by amine groups and poly(3-thiophene acetic acid) conducting polymer

    Energy Technology Data Exchange (ETDEWEB)

    Szabo, T.; Magyar, M.; Nagy, L. [Department of Medical Physics and Informatics, University of Szeged, H-6720 Szeged (Hungary); Nemeth, Z.; Hernadi, K. [Department of Applied and Environmental Chemistry, University of Szeged, H-6720 Szeged (Hungary); Endrodi, B.; Bencsik, G.; Visy, Cs. [Department of Physical Chemistry and Materials Science, University of Szeged, H-6720 Szeged (Hungary); Horvath, E.; Magrez, A.; Forro, L. [Institute of Physics of Complex Matter, Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne (Switzerland)

    2012-12-15

    A large number of studies have indicated recently that photosynthetic reaction center proteins (RC) bind successfully to nanostructures and their functional activity is largely retained. The major goal of current research is to find the most efficient systems and conditions for the photoelectric energy conversion and for the stability of this bio-nanocomposite. In our studies, we immobilized the RC protein on multiwalled carbon nanotubes (MWNT) through specific chemical binding to amine functional groups and through conducting polymer (poly(3-thiophene acetic acid), PTAA). Both structural (TEM, AFM) and functional (absorption change and conductivity) measurements has shown that RCs could be bound effectively to functionalized CNTs. The kinetics of the light induced absorption change indicated that RCs were still active in the composite and there was an interaction between the protein cofactors and the CNTs. The light generated photocurrent was measured in an electrochemical cell with transparent CNT electrode designed specially for this experiment. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  17. Electrostatics of the photosynthetic bacterial reaction center. Protonation of Glu L 212 and Asp L 213 - A new method of calculation.

    Science.gov (United States)

    Ptushenko, Vasily V; Cherepanov, Dmitry A; Krishtalik, Lev I

    2015-12-01

    Continuum electrostatic calculation of the transfer energies of anions from water into aprotic solvents gives the figures erroneous by order of magnitude. This is due to the hydrogen bond disruption that suggests the necessity to reconsider the traditional approach of the purely electrostatic calculation of the transfer energy from water into protein. In this paper, the method combining the experimental estimates of the transfer energies from water into aprotic solvent and the electrostatic calculation of the transfer energies from aprotic solvent into protein is proposed. Hydrogen bonds between aprotic solvent and solute are taken into account by introducing an imaginary aprotic medium incapable to form hydrogen bonds with the solute. Besides, a new treatment of the heterogeneous intraprotein dielectric permittivity based on the microscopic protein structure and electrometric measurements is elaborated. The method accounts semi-quantitatively for the electrostatic effect of diverse charged amino acid substitutions in the donor and acceptor parts of the photosynthetic bacterial reaction center from Rhodobacter sphaeroides. Analysis of the volatile secondary acceptor site QB revealed that in the conformation with a minimal distance between quinone QB and Glu L 212 the proton uptake upon the reduction of QB is prompted by Glu L 212 in alkaline and by Asp L 213 in slightly acidic regions. This agrees with the pH dependences of protonation degrees and the proton uptake. The method of pK calculation was applied successfully also for dissociation of Asp 26 in bacterial thioredoxin. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. Regional ocean-colour chlorophyll algorithms for the Red Sea

    KAUST Repository

    Brewin, Robert J.W.

    2015-05-18

    The Red Sea is a semi-enclosed tropical marine ecosystem that stretches from the Gulf of Suez and Gulf of Aqaba in the north, to the Gulf of Aden in the south. Despite its ecological and economic importance, its biological environment is relatively unexplored. Satellite ocean-colour estimates of chlorophyll concentration (an index of phytoplankton biomass) offer an observational platform to monitor the health of the Red Sea. However, little is known about the optical properties of the region. In this paper, we investigate the optical properties of the Red Sea in the context of satellite ocean-colour estimates of chlorophyll concentration. Making use of a new merged ocean-colour product, from the European Space Agency (ESA) Climate Change Initiative, and in situ data in the region, we test the performance of a series of ocean-colour chlorophyll algorithms. We find that standard algorithms systematically overestimate chlorophyll when compared with the in situ data. To investigate this bias we develop an ocean-colour model for the Red Sea, parameterised to data collected during the Tara Oceans expedition, that estimates remote-sensing reflectance as a function of chlorophyll concentration. We used the Red Sea model to tune the standard chlorophyll algorithms and the overestimation in chlorophyll originally observed was corrected. Results suggest that the overestimation was likely due to an excess of CDOM absorption per unit chlorophyll in the Red Sea when compared with average global conditions. However, we recognise that additional information is required to test the influence of other potential sources of the overestimation, such as aeolian dust, and we discuss uncertainties in the datasets used. We present a series of regional chlorophyll algorithms for the Red Sea, designed for a suite of ocean-colour sensors, that may be used for further testing.

  19. Chlorophyll derivatives for pest and disease control: Are they safe?

    International Nuclear Information System (INIS)

    Azizullah, Azizullah; Murad, Waheed

    2015-01-01

    Chlorophyll derivatives are getting widespread acceptance among the researchers as natural photosensitizers for photodynamic control of pests and disease vectors; however, rare attention has been given to evaluation of their toxicity to non-target organisms in the environment. This perspective article highlights that chlorophyll derivatives may not be as safe as believed and can possibly pose risk to non-target organisms in the environment. We invite the attention of environmental biologists, particularly ecotoxicologists, to contribute their role in making the application of chlorophyll derivatives more environmentally friendly and publicly acceptable

  20. Gamma ray induced chlorophyll and morphological mutants in grasspea

    International Nuclear Information System (INIS)

    Das, P.K.; Kundagrami, S.

    2000-01-01

    Higher dose of gamma ray treatment such as 30 kR promoted larger chlorophyll as well as morphological mutation frequency and spectrum. In both M 1 and M 2 generation marginata significantly out numbered other types of chlorophyll mutations. On the other hand, along morphological mutations stunted growth types were recovered more frequently. Both the genotypes Nirmal and P-24 differed greatly for their mutagenic specificity. In both M 1 and M 2 generation Nirmal recorded higher chlorophyll and morphological mutation frequency and spectrum indicating differential genotype response to different dosages of gamma ray treatment. (author)

  1. Chlorophyll derivatives for pest and disease control: Are they safe?

    Energy Technology Data Exchange (ETDEWEB)

    Azizullah, Azizullah, E-mail: azizswabi@gmail.com; Murad, Waheed

    2015-01-15

    Chlorophyll derivatives are getting widespread acceptance among the researchers as natural photosensitizers for photodynamic control of pests and disease vectors; however, rare attention has been given to evaluation of their toxicity to non-target organisms in the environment. This perspective article highlights that chlorophyll derivatives may not be as safe as believed and can possibly pose risk to non-target organisms in the environment. We invite the attention of environmental biologists, particularly ecotoxicologists, to contribute their role in making the application of chlorophyll derivatives more environmentally friendly and publicly acceptable.

  2. Photogeneration of charges in microcrystalline chlorophyll a

    International Nuclear Information System (INIS)

    Kassi, Hassan; Barazzouk, Said; Brullemans, Marc; Leblanc, Roger M.; Hotchandani, Surat

    2010-01-01

    The electric-field and temperature dependence of hole photogeneration in chlorophyll a (Chla) have been analyzed in terms of electric-field assisted thermal dissociation of charge pairs based on Onsager theory. An excellent agreement between the experimental and theoretical values of the slope-to-intercept ratio, S/I, for the plot of photogeneration efficiency vs. electric field at low field strengths provides a proof for the applicability of the Onsager approach to the photogeneration of charges in Chla. A value of 19 nm has been obtained for Coulomb capture radius, r c , from S/I. From the temperature dependence of photogeneration, the initial separation, r 0 , of photogenerated electron-hole has been evaluated, and has a value of 1.24 nm. This smaller r 0 compared to r c leads to a feeble dissociation probability of electron-hole pairs into free carriers, and may, among other factors, explain the low power conversion efficiencies of Chla photovoltaic cells.

  3. Photogeneration of charges in microcrystalline chlorophyll a

    Energy Technology Data Exchange (ETDEWEB)

    Kassi, Hassan [Scientech R and D, Inc., 2200 Rue Didbec S., Bureau 203, Trois-Rivieres, Trois-Rivieres, QC, G8Z 4H1 (Canada); Barazzouk, Said, E-mail: barazzos@uqtr.c [Groupe de Recherche en Biologie Vegetale, Universite du Quebec a Trois-Rivieres, Trois-Rivieres, QC, G9A 5H7 (Canada); Brullemans, Marc [Groupe de Recherche en Biologie Vegetale, Universite du Quebec a Trois-Rivieres, Trois-Rivieres, QC, G9A 5H7 (Canada); Leblanc, Roger M. [Department of Chemistry, University of Miami, P.O. Box 249118, Coral Gables, FL 33124-0431 (United States); Hotchandani, Surat [Groupe de Recherche en Biologie Vegetale, Universite du Quebec a Trois-Rivieres, Trois-Rivieres, QC, G9A 5H7 (Canada)

    2010-07-01

    The electric-field and temperature dependence of hole photogeneration in chlorophyll a (Chla) have been analyzed in terms of electric-field assisted thermal dissociation of charge pairs based on Onsager theory. An excellent agreement between the experimental and theoretical values of the slope-to-intercept ratio, S/I, for the plot of photogeneration efficiency vs. electric field at low field strengths provides a proof for the applicability of the Onsager approach to the photogeneration of charges in Chla. A value of 19 nm has been obtained for Coulomb capture radius, r{sub c}, from S/I. From the temperature dependence of photogeneration, the initial separation, r{sub 0}, of photogenerated electron-hole has been evaluated, and has a value of 1.24 nm. This smaller r{sub 0} compared to r{sub c} leads to a feeble dissociation probability of electron-hole pairs into free carriers, and may, among other factors, explain the low power conversion efficiencies of Chla photovoltaic cells.

  4. Assessment of water pollution by airborne measurement of chlorophyll

    Science.gov (United States)

    Arvesen, J. C.; Weaver, E. C.; Millard, J. P.

    1972-01-01

    Remote measurement of chlorophyll concentrations to determine extent of water pollution is discussed. Construction and operation of radiometer to provide measurement capability are explained. Diagram of equipment is provided.

  5. A database of chlorophyll a in Australian waters

    Science.gov (United States)

    Davies, Claire H.; Ajani, Penelope; Armbrecht, Linda; Atkins, Natalia; Baird, Mark E.; Beard, Jason; Bonham, Pru; Burford, Michele; Clementson, Lesley; Coad, Peter; Crawford, Christine; Dela-Cruz, Jocelyn; Doblin, Martina A.; Edgar, Steven; Eriksen, Ruth; Everett, Jason D.; Furnas, Miles; Harrison, Daniel P.; Hassler, Christel; Henschke, Natasha; Hoenner, Xavier; Ingleton, Tim; Jameson, Ian; Keesing, John; Leterme, Sophie C.; James McLaughlin, M.; Miller, Margaret; Moffatt, David; Moss, Andrew; Nayar, Sasi; Patten, Nicole L.; Patten, Renee; Pausina, Sarah A.; Proctor, Roger; Raes, Eric; Robb, Malcolm; Rothlisberg, Peter; Saeck, Emily A.; Scanes, Peter; Suthers, Iain M.; Swadling, Kerrie M.; Talbot, Samantha; Thompson, Peter; Thomson, Paul G.; Uribe-Palomino, Julian; van Ruth, Paul; Waite, Anya M.; Wright, Simon; Richardson, Anthony J.

    2018-02-01

    Chlorophyll a is the most commonly used indicator of phytoplankton biomass in the marine environment. It is relatively simple and cost effective to measure when compared to phytoplankton abundance and is thus routinely included in many surveys. Here we collate 173, 333 records of chlorophyll a collected since 1965 from Australian waters gathered from researchers on regular coastal monitoring surveys and ocean voyages into a single repository. This dataset includes the chlorophyll a values as measured from samples analysed using spectrophotometry, fluorometry and high performance liquid chromatography (HPLC). The Australian Chlorophyll a database is freely available through the Australian Ocean Data Network portal (https://portal.aodn.org.au/). These data can be used in isolation as an index of phytoplankton biomass or in combination with other data to provide insight into water quality, ecosystem state, and relationships with other trophic levels such as zooplankton or fish.

  6. Investigation into robust spectral indices for leaf chlorophyll estimation

    CSIR Research Space (South Africa)

    Main, R

    2011-11-01

    Full Text Available remote sensing data, new users are faced with a plethora of options when choosing an optical index to relate to their chosen or canopy parameter. The literature base regarding optical indices (particularly chlorophyll indices) is wide ranging...

  7. Relationship between chlorophyll-a and column primary production

    Digital Repository Service at National Institute of Oceanography (India)

    Dalal, S.G.; Bhargava, R.M.S.

    Relationship between surface chlorophyll a and column primary production has been established to help in estimating the latter more quickly and accurately. The equation derived is Primary Production, y = 0.54 Ln Chl a - 0.6. The relationship...

  8. Effects of copper stress on antioxidative enzymes, chlorophyll and ...

    African Journals Online (AJOL)

    Effects of copper stress on antioxidative enzymes, chlorophyll and protein content in Atriplex ... Journal Home > Vol 10, No 50 (2011) > ... The aim of this work was to investigate some enzymatic systems response of this plant to copper stress.

  9. Chlorophyll modulation of mixed layer thermodynamics in a mixed ...

    Indian Academy of Sciences (India)

    M. Senthilkumar (Newgen Imaging) 1461 1996 Oct 15 13:05:22

    in a mixed-layer isopycnal General Circulation Model – An ... three dimensional ocean circulation theory combined with solar radiation transfer process. 1. .... temperature decrease compared with simulation without chlorophyll (bottom panel).

  10. Endolithic chlorophyll d-containing phototrophs

    DEFF Research Database (Denmark)

    Behrendt, Lars; Larkum, Anthony W D; Norman, Anders

    2011-01-01

    hyperspectral and variable chlorophyll fluorescence imaging, scanning electron microscopy, photopigment analysis and DNA sequencing to show that Acaryochloris-like cyanobacteria thrive underneath crustose coralline algae in a widespread endolithic habitat on coral reefs. This finding suggests an important role...

  11. Modeling the bacterial photosynthetic reaction center. VII. Full simulation of the intervalence hole-transfer absorption spectrum of the special-pair radical cation

    International Nuclear Information System (INIS)

    Reimers, Jeffrey R.; Hush, Noel S.

    2003-01-01

    reaction centers from photosystems I, II, etc., facilitating a deeper understanding of the role of the special pair in initiating primary charge separation during photosynthesis

  12. Manipulating the Energetics and Rates of Electron Transfer in Rhodobacter capsulatus Reaction Centers with Asymmetric Pigment Content

    Energy Technology Data Exchange (ETDEWEB)

    Faries, Kaitlyn M. [Department; Dylla, Nicholas P. [Biosciences Division, Argonne National Laboratory, Lemont, Illinois 60439, United States; Hanson, Deborah K. [Biosciences Division, Argonne National Laboratory, Lemont, Illinois 60439, United States; Holten, Dewey [Department; Laible, Philip D. [Biosciences Division, Argonne National Laboratory, Lemont, Illinois 60439, United States; Kirmaier, Christine [Department

    2017-07-17

    Seemingly redundant parallel pathways for electron transfer (ET), composed of identical sets of cofactors, are a cornerstone feature of photosynthetic reaction centers (RCs) involved in light-energy conversion. In native bacterial RCs, both A and B branches house one bacteriochlorophyll (BChl) and one bacteriopheophytin (BPh), but the A branch is used exclusively. Described herein are the results-obtained for two Rhodobacter capsulatus RCs with an unnaturally high degree of cofactor asymmetry, two BPh on the RC's B side and two BChl on the A side. These pigment changes derive, respectively, from the His(M180)Leu mutation [a BPh ((Phi(B)) replaces the B-side BChl (BB)], and the Leu(M212)His mutation [a BChl (beta(A))) replaces the A-side BPh (H-A)]. Additionally, Tyr(M208)Phe was employed to disfavor ET to the A branch; in one mutant, Val(M131)Glu creates a hydrogen bond to H-B to enhance ET to H-B. In both Phi(B) mutants, the decay kinetics of the excited primary ET donor (P*) resolve three populations with lifetimes of similar to 9 ps (50-60%), similar to 40 ps (10-20%), and similar to 200 ps (20-30%), with P+Phi(-)(B) formed predominantly from the 9 ps fraction. The 50-60% yield of P+Phi(B)- is the highest yet observed for a Phi(B)-containing RC. The results provide insight into factors needed for efficient multistep ET.

  13. The rate of second electron transfer to QB(-) in bacterial reaction center of impaired proton delivery shows hydrogen-isotope effect.

    Science.gov (United States)

    Maróti, Ágnes; Wraight, Colin A; Maróti, Péter

    2015-02-01

    The 2nd electron transfer in reaction center of photosynthetic bacterium Rhodobacter sphaeroides is a two step process in which protonation of QB(-) precedes interquinone electron transfer. The thermal activation and pH dependence of the overall rate constants of different RC variants were measured and compared in solvents of water (H2O) and heavy water (D2O). The electron transfer variants where the electron transfer is rate limiting (wild type and M17DN, L210DN and H173EQ mutants) do not show solvent isotope effect and the significant decrease of the rate constant of the second electron transfer in these mutants is due to lowering the operational pKa of QB(-)/QBH: 4.5 (native), 3.9 (L210DN), 3.7 (M17DN) and 3.1 (H173EQ) at pH7. On the other hand, the proton transfer variants where the proton transfer is rate limiting demonstrate solvent isotope effect of pH-independent moderate magnitude (2.11±0.26 (WT+Ni(2+)), 2.16±0.35 (WT+Cd(2+)) and 2.34±0.44 (L210DN/M17DN)) or pH-dependent large magnitude (5.7 at pH4 (L213DN)). Upon deuteration, the free energy and the enthalpy of activation increase in all proton transfer variants by about 1 kcal/mol and the entropy of activation becomes negligible in L210DN/M17DN mutant. The results are interpreted as manifestation of equilibrium and kinetic solvent isotope effects and the structural, energetic and kinetic possibility of alternate proton delivery pathways are discussed. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. Langmuir-Blodgett and X-ray diffraction studies of isolated photosystem II reaction centers in monolayers and multilayers: physical dimensions of the complex.

    Science.gov (United States)

    Uphaus, R A; Fang, J Y; Picorel, R; Chumanov, G; Wang, J Y; Cotton, T M; Seibert, M

    1997-04-01

    The photosystem II (PSII) reaction center (RC) is a hydrophobic intrinsic protein complex that drives the water-oxidation process of photosynthesis. Unlike the bacterial RC complex, an X-ray crystal structure of the PSII RC is not available. In order to determine the physical dimensions of the isolated PSII RC complex, we applied Langmuir techniques to determine the cross-sectional area of an isolated RC in a condensed monolayer film. Low-angle X-ray diffraction results obtained by examining Langmuir-Blodgett multilayer films of alternating PSII RC/Cd stearate monolayers were used to determine the length (or height; z-direction, perpendicular to the plane of the original membrane) of the complex. The values obtained for a PSII RC monomer were 26 nm2 and 4.8 nm, respectively, and the structural integrity of the RC in the multilayer film was confirmed by several approaches. Assuming a cylindrical-type RC structure, the above dimensions lead to a predicted volume of about 125 nm3. This value is very close to the expected volume of 118 nm3, calculated from the known molecular weight and partial specific volume of the PSII RC proteins. This same type of comparison was also made with the Rhodobacter sphaeroides RC based on published data, and we conclude that the PSII RC is much shorter in length and has a more regular solid geometric structure than the bacterial RC. Furthermore, the above dimensions of the PSII RC and those of PSII core (RC plus proximal antenna) proteins protruding outside the plane of the PSII membrane into the lumenal space as imaged by scanning tunneling microscopy (Seibert, Aust. J. Pl. Physiol. 22, 161-166, 1995) fit easily into the known dimensions of the PSII core complex visualized by others as electron-density projection maps. From this we conclude that the in situ PSII core complex is a dimeric structure containing two copies of the PSII RC.

  15. Tomato seeds maturity detection system based on chlorophyll fluorescence

    Science.gov (United States)

    Li, Cuiling; Wang, Xiu; Meng, Zhijun

    2016-10-01

    Chlorophyll fluorescence intensity can be used as seed maturity and quality evaluation indicator. Chlorophyll fluorescence intensity of seed coats is tested to judge the level of chlorophyll content in seeds, and further to judge the maturity and quality of seeds. This research developed a detection system of tomato seeds maturity based on chlorophyll fluorescence spectrum technology, the system included an excitation light source unit, a fluorescent signal acquisition unit and a data processing unit. The excitation light source unit consisted of two high power LEDs, two radiators and two constant current power supplies, and it was designed to excite chlorophyll fluorescence of tomato seeds. The fluorescent signal acquisition unit was made up of a fluorescence spectrometer, an optical fiber, an optical fiber scaffolds and a narrowband filter. The data processing unit mainly included a computer. Tomato fruits of green ripe stage, discoloration stage, firm ripe stage and full ripe stage were harvested, and their seeds were collected directly. In this research, the developed tomato seeds maturity testing system was used to collect fluorescence spectrums of tomato seeds of different maturities. Principal component analysis (PCA) method was utilized to reduce the dimension of spectral data and extract principal components, and PCA was combined with linear discriminant analysis (LDA) to establish discriminant model of tomato seeds maturity, the discriminant accuracy was greater than 90%. Research results show that using chlorophyll fluorescence spectrum technology is feasible for seeds maturity detection, and the developed tomato seeds maturity testing system has high detection accuracy.

  16. Estimating chlorophyll content from Eucalyptus dunnii leaves by reflectance values

    Directory of Open Access Journals (Sweden)

    João Alexandre Lopes Dranski

    2016-06-01

    Full Text Available This study aimed to estimate photosynthetic pigments contents from leaves of Eucalyptus dunni Maiden based on values of reflectance spectra of red, green and blue colors obtained with a digital color analyzer. We collected fifty leaves from the lower third of the crown of twenty trees including young as well as mature leaves. From each leaf an area of 14 cm2 of the leaf blade was cut in which we measured reflectance values on the red, green and blue spectra with a portable digital colorimeter, obtained relative index of chlorophyll with a SPAD – 502 and determined the content of the chlorophyll a, b, and a + b by classic method of solvent extraction. We submitted the data to multiple linear regression and nonlinear analysis at 5% of error probability. It was evaluated the occurrence of multicollinearity. The negative exponential model resulted in good fit when data from red spectrum was used for chlorophyll a, green spectrum for chlorophyll b and a + b, making possible correlation coefficients between the estimated values and the extracted above 0.85. Except for the chlorophyll a content, the accuracy in estimates of photosynthetic pigments were higher than estimated by the chlorophyll meter, even with linearity between methods. Therefore, it is possible to estimate photosynthetic pigments on E. dunni leaves through values of red and green wavelengths from a digital color analyser.

  17. Water-Soluble Chlorophyll Protein (WSCP) Stably Binds Two or Four Chlorophylls.

    Science.gov (United States)

    Palm, Daniel M; Agostini, Alessandro; Tenzer, Stefan; Gloeckle, Barbara M; Werwie, Mara; Carbonera, Donatella; Paulsen, Harald

    2017-03-28

    Water-soluble chlorophyll proteins (WSCPs) of class IIa from Brassicaceae form tetrameric complexes containing one chlorophyll (Chl) per apoprotein but no carotenoids. The complexes are remarkably stable toward dissociation and protein denaturation even at 100 °C and extreme pH values, and the Chls are partially protected against photooxidation. There are several hypotheses that explain the biological role of WSCPs, one of them proposing that they function as a scavenger of Chls set free upon plant senescence or pathogen attack. The biochemical properties of WSCP described in this paper are consistent with the protein acting as an efficient and flexible Chl scavenger. At limiting Chl concentrations, the recombinant WSCP apoprotein binds substoichiometric amounts of Chl (two Chls per tetramer) to form complexes that are as stable toward thermal dissociation, denaturation, and photodamage as the fully pigmented ones. If more Chl is added, these two-Chl complexes can bind another two Chls to reach the fully pigmented state. The protection of WSCP Chls against photodamage has been attributed to the apoprotein serving as a diffusion barrier for oxygen, preventing its access to triplet excited Chls and, thus, the formation of singlet oxygen. By contrast, the sequential binding of Chls by WSCP suggests a partially open or at least flexible structure, raising the question of how WSCP photoprotects its Chls without the help of carotenoids.

  18. Calculation of Transactinide Homolog Isotope Production Reactions Possible with the Center for Accelerator Mass Spectrometry (CAMS) at Lawrence Livermore National Laboratory

    International Nuclear Information System (INIS)

    Moody, K.J.; Shaughnessy, D.A.; Gostic, J.M.

    2011-01-01

    The LLNL heavy element group has been investigating the chemical properties of the heaviest elements over the past several years. The properties of the transactinides (elements with Z > 103) are often unknown due to their low production rates and short half-lives, which require lengthy cyclotron irradiations in order to make enough atoms for statistically significant evaluations of their chemistry. In addition, automated chemical methods are often required to perform consistent and rapid chemical separations on the order of minutes for the duration of the experiment, which can last from weeks to months. Separation methods can include extraction chromatography, liquid-liquid extraction, or gas-phase chromatography. Before a lengthy transactinide experiment can be performed at an accelerator, a large amount of preparatory work must be done both to ensure the successful application of the chosen chemical system to the transactinide chemistry problem being addressed, and to evaluate the behavior of the lighter elemental homologs in the same chemical system. Since transactinide chemistry is literally performed on one single atom, its chemical properties cannot be determined from bulk chemical matrices, but instead must be inferred from the behavior of the lighter elements that occur in its chemical group and in those of its neighboring elements. By first studying the lighter group homologs in a particular chemical system, when the same system is applied to the transactinide element under investigation, its decay properties can be directly compared to those of the homologues, thereby allowing an inference of its own chemistry. The Center for Accelerator Mass Spectrometry (CAMS) at Lawrence Livermore National Laboratory (LLNL) includes a 1 MV Tandem accelerator, capable of accelerating light ions such as protons to energies of roughly 15 MeV. By using the CAMS beamline, tracers of transactinide homolog elements can be produced both for development of chemical systems and

  19. Calculation of Transactinide Homolog Isotope Production Reactions Possible with the Center for Accelerator Mass Spectrometry (CAMS) at Lawrence Livermore National Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Moody, K J; Shaughnessy, D A; Gostic, J M

    2011-11-29

    The LLNL heavy element group has been investigating the chemical properties of the heaviest elements over the past several years. The properties of the transactinides (elements with Z > 103) are often unknown due to their low production rates and short half-lives, which require lengthy cyclotron irradiations in order to make enough atoms for statistically significant evaluations of their chemistry. In addition, automated chemical methods are often required to perform consistent and rapid chemical separations on the order of minutes for the duration of the experiment, which can last from weeks to months. Separation methods can include extraction chromatography, liquid-liquid extraction, or gas-phase chromatography. Before a lengthy transactinide experiment can be performed at an accelerator, a large amount of preparatory work must be done both to ensure the successful application of the chosen chemical system to the transactinide chemistry problem being addressed, and to evaluate the behavior of the lighter elemental homologs in the same chemical system. Since transactinide chemistry is literally performed on one single atom, its chemical properties cannot be determined from bulk chemical matrices, but instead must be inferred from the behavior of the lighter elements that occur in its chemical group and in those of its neighboring elements. By first studying the lighter group homologs in a particular chemical system, when the same system is applied to the transactinide element under investigation, its decay properties can be directly compared to those of the homologues, thereby allowing an inference of its own chemistry. The Center for Accelerator Mass Spectrometry (CAMS) at Lawrence Livermore National Laboratory (LLNL) includes a 1 MV Tandem accelerator, capable of accelerating light ions such as protons to energies of roughly 15 MeV. By using the CAMS beamline, tracers of transactinide homolog elements can be produced both for development of chemical systems and

  20. Evaluation of nitrogen status and total chlorophyll in longkong (Aglaia dookkoo Griff. leaves under water stress using a chlorophyll meter

    Directory of Open Access Journals (Sweden)

    Sdoodee, S.

    2005-07-01

    Full Text Available A chlorophyll meter (SPAD-502 was used to assess nitrogen status and total chlorophyll in longkong leaves, leaves from twelve of 10-year-old trees grown in the experimental plot at Prince of Songkla University, Songkhla province. The relationship between SPAD-502 meter reading and nitrogen status and total chlorophyll content analyzed in the laboratory was evaluated during 8 months (May-December 2003. It was found that the trend of the relationships in each month was similar. There was no significant differenceamong regression linears of all months. The data of 8 months showed that SPAD-reading and nitrogen content, and SPAD-reading and total chlorophyll content were related in a positive manner. They were Y = 0.19X+10.10, r = 0.76** (n = 240, and Y = 0.43X-7.89, r = 0.79** (n = 400, respectively. The SPAD-502 was then used to assess total nitrogen and total chlorophyll content during imposed water stress. Fifteen 4-yearold plants were grown in pots (each pot containing 50 kg soil volume. The experiment was arranged in acompletely randomized design with 3 treatments: (1 daily watering (2 once watering on day 7 (3 no watering with 5 replications during 14 days of the experimental period. Measurements showed a continuous decrease of SPAD-reading in the treatment of no watering. On day 14, a significant difference of SPAD- reading values between the treatment of daily watering and no watering was found. Then, the values of nitrogen content and total chlorophyll were assessed by using the linear regression equations. From the result, it is suggested that the measurement by chlorophyll meter is a rapid technique for the evaluation of total chlorophyll and nitrogen status in longkong leaves during water stress.

  1. HPLC Analysis of Chlorophyll a, Chlorophyll b, and Beta-Carotene in Collard Greens: A Project for a Problem-Oriented Laboratory Course.

    Science.gov (United States)

    Silveira, Augustine, Jr.; And Others

    1984-01-01

    High performance liquid chromatography (HPLC) is used to separate and quantitate beta-carotene, chlorophyll a, and chlorophyll b originating from collard greens. Experimental procedures used and typical results obtained are discussed. (JN)

  2. CHLOROPHYLL a FLUORESCENCE ANALYSIS IN FORESTS

    Directory of Open Access Journals (Sweden)

    M. Pollastrini

    2016-03-01

    Full Text Available A European-wide assessment of chlorophyll a fluorescence (ChlF, prompt fluorescence on dark-adapted samples parameters in forest ecosystems was carried out in the years 2012-2013, within the 7FP FunDivEUROPE project. A total of 1596 trees growing in 209 stands distributed in six countries, from Mediterranean to boreal sites, were sampled. This paper shows the applicability of the ChlF in forest ecology surveys, the protocols adopted for leaf sampling and ChlF measurements, the variability of the ChlF parameters within and between trees, their dependence to environmental factors and the relationships with other functional leaf traits. The most relevant findings were as follows: (i The least variable ChlF parameter within and between the trees was the maximum quantum yield of primary photochemistry (FV/FM, whereas the performance indices (PIABS and PITOT showed the highest variability; (ii for a given tree, the ChlF parameters measured at two heights of the crown (top and bottom leaves were correlated and, in coniferous species, the ChlF parameters were correlated between different needle age classes (from the current year and previous year; (iii the ChlF parameters showed a geographical pattern, and the photochemical performance of the forest trees was higher in central Europe than in the edge sites (northernmost and southernmost; and (iv ChlF parameters showed different sensitivity to specific environmental factors: FV/FM increased with the increase of the leaf area index of stands and soil fertility; ΔVIP was reduced under high temperature and drought. The photochemical responses of forest tree species, analyzed with ChlF parameters, were influenced by the ecology of the trees (i.e. their functional groups, continental distribution, successional status, etc., tree species’ richness and composition of the stands. Our results support the applicability and usefulness of the ChlF in forest monitoring investigations on a large spatial scale and

  3. [Effects of plastic film mulching and rain harvesting modes on chlorophyll fluorescence characteristics, yield and water use efficiency of dryland maize].

    Science.gov (United States)

    Li, Shang-Zhong; Fan, Ting-Lu; Wang, Yong; Zhao, Gang; Wang, Lei; Tang, Xiao-Ming; Dang, Yi; Zhao, Hui

    2014-02-01

    The differences on chlorophyll fluorescence parameters, yield and water use efficiency of dryland maize were compared among full plastic film mulching on double ridges and planting in catchment furrows (FFDRF), half plastic film mulching on double ridges and planting in catchment furrows (HFDRF), plastic film mulching on ridge and planting in film-side (FS), and flat planting with no plastic film mulching (NM) under field conditions in dry highland of Loess Plateau in 2007-2012. The results showed that fluorescence yield (Fo), the maximum fluorescence yield (Fm), light-adapted fluorescence yield when PS II reaction centers were totally open (F), light-adapted fluorescence yield when PS II reaction centers closed (Fm'), the maximal photochemical efficiency of PS II (Fv/Fm), the actual photochemical efficiency of PS II in the light (Phi PS II), the relative electron transport rate (ETR), photochemical quenching (qP) and non-photochemical quenching (qN) in maize leaves of FFDRF were higher than that of control (NM), and the value of 1-qP was lower than that of control, at 13:00, chlorophyll fluorescence parameters values of FFDRF was significantly higher than control, which were increased by 5.3%, 56.8%, 10.7%, 36.3%, 23.6%, 56.7%, 64.4%, 45.5%, 23.6% and -55.6%, respectively, compared with the control. Yield and water use efficiency of FFDRF were the highest in every year no matter dry year, normal year, humid year and hail disaster year. Average yield and water use efficiency of FFDRF were 12,650 kg x hm(-2) and 40.4 kg x mm(-1) x hm(-2) during 2007-2012, increased by 57.8% and 61.6% compared with the control, respectively, and also significantly higher compared with HFDRF and PS. Therefore, it was concluded that FFDRF had significantly increased the efficiency of light energy conversion and improved the production capacity of dryland maize.

  4. Chlorophyll a is a favorable substrate for Chlamydomonas Mg-dechelatase encoded by STAY-GREEN.

    Science.gov (United States)

    Matsuda, Kaori; Shimoda, Yousuke; Tanaka, Ayumi; Ito, Hisashi

    2016-12-01

    Mg removal from chlorophyll by Mg-dechelatase is the first step of chlorophyll degradation. Recent studies showed that in Arabidopsis, Stay Green (SGR) encodes Mg-dechelatase. Though the Escherichia coli expression system is advantageous for investigating the properties of Mg-dechelatase, Arabidopsis Mg-dechelatase is not successfully expressed in E. coli. Chlamydomonas reinhardtii SGR (CrSGR) has a long, hydrophilic tail, suggesting that active CrSGR can be expressed in E. coli. After the incubation of chlorophyll a with CrSGR expressed in E. coli, pheophytin a accumulated, indicating that active CrSGR was expressed in E. coli. Substrate specificity of CrSGR against chlorophyll b and an intermediate molecule of the chlorophyll b degradation pathway was examined. CrSGR exhibited no activity against chlorophyll b and low activity against 7-hydroxymethyl chlorophyll a, consistent with the fact that chlorophyll b is degraded only after conversion to chlorophyll a. CrSGR exhibited low activity against divinyl chlorophyll a and chlorophyll a', and no activity against chlorophyllide a, protochlorophyll a, chlorophyll c 2 , and Zn-chlorophyll a. These observations indicate that chlorophyll a is the most favorable substrate for CrSGR. When CrSGR was expressed in Arabidopsis cells, the chlorophyll content decreased, further confirming that SGR has Mg-dechelating activity in chloroplasts. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  5. Structure and function of cytochrome c2 in electron transfer complexes with the photosynthetic reaction center of Rhodobacter sphaeroides: optical linear dichroism and EPR.

    Science.gov (United States)

    Drepper, F; Mathis, P

    1997-02-11

    The photosynthetic reaction center (RC) and its secondary electron donor the water-soluble cytochrome (cyt) c2 from the purple bacterium Rhodobacter sphaeroides have been used in cross-linked and non-cross-linked complexes, oriented in compressed gels or partially dried multilayers, to study the respective orientation of the primary donor P (BChl dimer) and of cyt c2. Three methods were used: (i) Polarized optical absorption spectra at 295 and 10 K were measured and the linear dichroism of the two individual transitions (Qx, Qy), which are nearly degenerate within the alpha-band of reduced cyt c2, was determined. Attribution of the polarization directions to the molecular axes within the heme plane yielded the average cyt orientation in the complexes. (ii) Time-resolved flash absorption measurements using polarized light allowed determination of the orientation of cyt c2 in complexes which differ in their kinetics of electron transfer. (iii) EPR spectroscopy of ferricyt c2 in cross-linked RC-cyt c2 complexes was used to determine the angle between the heme and the membrane plane. The results suggest the following structural properties for the docking of cyt c2 to the RC: (i) In cross-linked complexes, the two cytochromes displaying half-lives of 0.7 and 60 micros for electron transfer to P+ are similarly oriented (difference plane is parallel to the symmetry axis of the RC (0 degrees +/- 10 degrees). Moreover, the Qy transition, which is assumed to be polarized within the ring III-ring I direction of the heme plane, makes an angle of 56 degrees +/- 1 degree with the symmetry axis. (iii) The dichroism spectrum for the fast phase (0.7 micros) for the non-cross-linked cyt c2-RC complex suggests an orientation similar to that of cross-linked cyt c2, but the heme plane is tilted about 20 degrees closer to the membrane. An alternative model is that two or more bound states of cyt c2 with heme plane tilt angles between 0 degrees and 30 degrees allow the fast electron

  6. APPLICATION OF MODULATED CHLOROPHYLL FLUORESCENCE AND MODULATED CHLOROPHYLL FLUORESCENCE IMAGING IN STUDYING ENVIRONMENTAL STRESSES EFFECT

    Directory of Open Access Journals (Sweden)

    L. Guidi

    2016-03-01

    Full Text Available Chlorophyll (Chl a fluorescence is a widely used tool to monitor the photosynthetic process in plants subjected to environmental stresses.this review reports the theoretical bases of Chl fluorescence, and the significance of the most important Chl fluorescence parameters. it also reportshow these parameters can be utilised to estimate changes in photosystem ii (PSII photochemistry, linear electron flux and energy dissipationmechanisms. the relation between actual PSII photochemistry and CO2 assimilation is discussed, as is the role of photochemical andnon-photochemical quenching in inducing changes in PSII activity. the application of Chl fluorescence imaging to study heterogeneity on leaflamina is also considered. this review summarises only some of the results obtained by this methodology to study the effects of differentenvironmental stresses, namely water and nutrients availability, pollutants, temperature and salinity.

  7. Chlorophyll biosynthesis and assembly into chlorophyll-protein complexes in isolated developing chloroplasts

    International Nuclear Information System (INIS)

    Bhaya, D.; Castelfranco, P.A.

    1985-01-01

    Isolated developing plastids from greening cucumber cotyledons or from photoperiodically grown pea seedlings incorporated 14 C-labeled 5-aminolevulinic acid (ALA) into chlorophyll (Chl). Incorporation was light dependent, enhanced by S-adenosylmethionine, and linear for 1 hr. The in vitro rate of Chl synthesis from ALA was comparable to the in vivo rate of Chl accumulation. Levulinic acid and dioxoheptanoic acid strongly inhibited Chl synthesis but not plastid protein synthesis. Neither chloramphenicol nor spectinomycin affected Chl synthesis, although protein synthesis was strongly inhibited. Components of thylakoid membranes from plastids incubated with [ 14 C]ALA were resolved by electrophoresis and then subjected to autoradiography. This work showed that (i) newly synthesized Chl was assembled into Chl-protein complexes and (ii) the inhibition of protein synthesis during the incubation did not alter the labeling pattern. Thus, there was no observable short-term coregulation between Chl synthesis (from ALA) and the synthesis of membrane proteins in isolated plastids

  8. Conformational heterogeneity of the bacteriopheophytin electron acceptor HA in reaction centers from Rhodopseudomonas viridis revealed by Fourier transform infrared spectroscopy and site-directed mutagenesis.

    Science.gov (United States)

    Breton, J; Bibikova, M; Oesterhelt, D; Nabedryk, E

    1999-08-31

    The light-induced Fourier transform infrared (FTIR) difference spectra corresponding to the photoreduction of either the HA bacteriopheophytin electron acceptor (HA-/HA spectrum) or the QA primary quinone (QA-/QA spectrum) in photosynthetic reaction centers (RCs) of Rhodopseudomonas viridis are reported. These spectra have been compared for wild-type (WT) RCs and for two site-directed mutants in which the proposed interactions between the carbonyls on ring V of HA and the RC protein have been altered. In the mutant EQ(L104), the putative hydrogen bond between the protein and the 9-keto C=O of HA should be affected by changing Glu L104 to a Gln. In the mutant WF(M250), the van der Waals interactions between Trp M250 and the 10a-ester C=O of HA should be modified. The characteristic effects of both mutations on the FTIR spectra support the proposed interactions and allow the IR modes of the 9-keto and 10a-ester C=O of HA and HA- to be assigned. Comparison of the HA-/HA and QA-/QA spectra leads us to conclude that the QA-/QA IR signals in the spectral range above 1700 cm-1 are largely dominated by contributions from the electrostatic response of the 10a-ester C=O mode of HA upon QA photoreduction. A heterogeneity in the conformation of the 10a-ester C=O mode of HA in WT RCs, leading to three distinct populations of HA, appears to be related to differences in the hydrogen-bonding interactions between the carbonyls of ring V of HA and the RC protein. The possibility that this structural heterogeneity is related to the observed multiexponential kinetics of electron transfer and the implications for primary processes are discussed. The effect of 1H/2H exchange on the QA-/QA spectra of the WT and mutant RCs shows that neither Glu L104 nor any other exchangeable carboxylic residue changes appreciably its protonation state upon QA reduction.

  9. Report on the second consultants' meeting of nuclear reaction data centers Kiev, USSR, 11-16 April 1977. Including the thirteenth four-center meeting and the third meeting on charged particle nuclear data compilation

    International Nuclear Information System (INIS)

    Lemmel, H.D.

    1977-10-01

    This second ''NRDC meeting'' combined the 13th ''four centers meeting'' (consultants' meeting of the four neutron nuclear data centers) with the third ''CPND meeting'' (consultants' meeting on charged particle nuclear data compilation). In Part I of the meeting, the neutron data centers held a special session on neutron data matters, in particular on the jointly operated neutron data index CINDA, whereas all items of more general interest, in particular the data exchange system EXFOR, were treated in Part II of the meeting

  10. An overview of remote sensing of chlorophyll fluorescence

    Science.gov (United States)

    Xing, Xiao-Gang; Zhao, Dong-Zhi; Liu, Yu-Guang; Yang, Jian-Hong; Xiu, Peng; Wang, Lin

    2007-03-01

    Besides empirical algorithms with the blue-green ratio, the algorithms based on fluorescence are also important and valid methods for retrieving chlorophyll-a concentration in the ocean waters, especially for Case II waters and the sea with algal blooming. This study reviews the history of initial cognitions, investigations and detailed approaches towards chlorophyll fluorescence, and then introduces the biological mechanism of fluorescence remote sensing and main spectral characteristics such as the positive correlation between fluorescence and chlorophyll concentration, the red shift phenomena. Meanwhile, there exist many influence factors that increase complexity of fluorescence remote sensing, such as fluorescence quantum yield, physiological status of various algae, substances with related optical property in the ocean, atmospheric absorption etc. Based on these cognitions, scientists have found two ways to calculate the amount of fluorescence detected by ocean color sensors: fluorescence line height and reflectance ratio. These two ways are currently the foundation for retrieval of chlorophyl l - a concentration in the ocean. As the in-situ measurements and synchronous satellite data are continuously being accumulated, the fluorescence remote sensing of chlorophyll-a concentration in Case II waters should be recognized more thoroughly and new algorithms could be expected.

  11. Instrumentation in Developing Chlorophyll Fluorescence Biosensing: A Review

    Directory of Open Access Journals (Sweden)

    Jesus R. Millan-Almaraz

    2012-08-01

    Full Text Available Chlorophyll fluorescence can be defined as the red and far-red light emitted by photosynthetic tissue when it is excited by a light source. This is an important phenomenon which permits investigators to obtain important information about the state of health of a photosynthetic sample. This article reviews the current state of the art knowledge regarding the design of new chlorophyll fluorescence sensing systems, providing appropriate information about processes, instrumentation and electronic devices. These types of systems and applications can be created to determine both comfort conditions and current problems within a given subject. The procedure to measure chlorophyll fluorescence is commonly split into two main parts; the first involves chlorophyll excitation, for which there are passive or active methods. The second part of the procedure is to closely measure the chlorophyll fluorescence response with specialized instrumentation systems. Such systems utilize several methods, each with different characteristics regarding to cost, resolution, ease of processing or portability. These methods for the most part include cameras, photodiodes and satellite images.

  12. Instrumentation in Developing Chlorophyll Fluorescence Biosensing: A Review

    Science.gov (United States)

    Fernandez-Jaramillo, Arturo A.; Duarte-Galvan, Carlos; Contreras-Medina, Luis M.; Torres-Pacheco, Irineo; de J. Romero-Troncoso, Rene; Guevara-Gonzalez, Ramon G.; Millan-Almaraz, Jesus R.

    2012-01-01

    Chlorophyll fluorescence can be defined as the red and far-red light emitted by photosynthetic tissue when it is excited by a light source. This is an important phenomenon which permits investigators to obtain important information about the state of health of a photosynthetic sample. This article reviews the current state of the art knowledge regarding the design of new chlorophyll fluorescence sensing systems, providing appropriate information about processes, instrumentation and electronic devices. These types of systems and applications can be created to determine both comfort conditions and current problems within a given subject. The procedure to measure chlorophyll fluorescence is commonly split into two main parts; the first involves chlorophyll excitation, for which there are passive or active methods. The second part of the procedure is to closely measure the chlorophyll fluorescence response with specialized instrumentation systems. Such systems utilize several methods, each with different characteristics regarding to cost, resolution, ease of processing or portability. These methods for the most part include cameras, photodiodes and satellite images. PMID:23112686

  13. Chlorophyll as a biomarker for early disease diagnosis

    Science.gov (United States)

    Manzoor Atta, Babar; Saleem, M.; Ali, Hina; Arshad, Hafiz Muhammad Imran; Ahmed, M.

    2018-06-01

    The current study was designed to identify the stage for the diagnosis of disease before visible symptoms appeared. Fluorescence spectroscopy has been employed to identify disease signatures for its early diagnosis in rice plant leaves. Bacterial leaf blight (BLB) diseased and healthy leaf samples were collected from the rice fields in September, 2017 which were then used to record spectra using an excitation wavelength at 410 nm. The spectral range of emission was set from 420 to 800 nm which covers the blue–green and the chlorophyll bands. It was found that diseased leaves have a narrower ‘chlorophyll a’ band than healthy ones, and furthermore, that the emission band at 730 nm was either declined or depleted in the sample with high infection symptoms. In contrast, the blue–green region was observed to increase due to the emergence of disease. As the band intensity of chlorophyll decreases during infection, this decrease in chlorophyll content and increase in the blue–green spectral region could provide a new approach for predicting BLB at an early stage. The important finding was that the chlorophyll degradation and rise in the blue–green region take place in leaves with BLB or during BLB infection. Principal component analysis has been applied to spectral data which successfully separated diseased samples from healthy ones even with very small spectral variations.

  14. Tuning cofactor redox potentials: the 2-methoxy dihedral angle generates a redox potential difference of >160 mV between the primary (Q(A)) and secondary (Q(B)) quinones of the bacterial photosynthetic reaction center.

    Science.gov (United States)

    Taguchi, Alexander T; Mattis, Aidas J; O'Malley, Patrick J; Dikanov, Sergei A; Wraight, Colin A

    2013-10-15

    Only quinones with a 2-methoxy group can act simultaneously as the primary (QA) and secondary (QB) electron acceptors in photosynthetic reaction centers from Rhodobacter sphaeroides. (13)C hyperfine sublevel correlation measurements of the 2-methoxy in the semiquinone states, SQA and SQB, were compared with quantum mechanics calculations of the (13)C couplings as a function of the dihedral angle. X-ray structures support dihedral angle assignments corresponding to a redox potential gap (ΔEm) between QA and QB of ~180 mV. This is consistent with the failure of a ubiquinone analogue lacking the 2-methoxy to function as QB in mutant reaction centers with a ΔEm of ≈160-195 mV.

  15. Factors associated with acute oral mucosal reaction induced by radiotherapy in head and neck squamous cell carcinoma: A retrospective single-center experience.

    Science.gov (United States)

    Tao, Zhenchao; Gao, Jin; Qian, Liting; Huang, Yifan; Zhou, Yan; Yang, Liping; He, Jian; Yang, Jing; Wang, Ru; Zhang, Yangyang

    2017-12-01

    To investigate risk factors for acute oral mucosal reaction during head and neck squamous cell carcinoma radiotherapy.A retrospective study of patients with head and neck squamous cell carcinoma who underwent radiotherapy from November 2013 to May 2016 in Anhui Provincial Cancer Hospital was conducted. Data on the occurrence and severity of acute oral mucositis were extracted from clinical records. Based on the Radiation Therapy Oncology Group (RTOG) grading of acute radiation mucosal injury, the patients were assigned into acute reaction (grades 2-4) and minimum reaction (grades 0-1) groups. Preradiotherapy characteristics and treatment factors were compared between the 2 groups. Multivariate logistic regression analysis was used to detect the independent factors associated with acute oral mucosal reactions.Eighty patients completed radiotherapy during the study period. Oral mucosal reactions were recorded as 25, 31, and 24 cases of grades 1, 2, and 3 injuries, respectively. Significant differences between acute reaction and minimum reaction groups were detected in cancer lymph node (N) staging, smoking and diabetes history, pretreatment platelet count and T-Helper/T-Suppressor lymphocyte (Th/Ts) ratio, concurrent chemotherapy, and total and single irradiation doses.Multivariate analysis showed that N stage, smoking history, single dose parapharyngeal irradiation, and pretreatment platelet count were independent risk factors for acute radiation induced oral mucosal reaction. Smoking history, higher grading of N stage, higher single dose irradiation, and lower preirradiation platelet count may increase the risk and severity of acute radiation oral mucosal reaction in radiotherapy of head and neck cancer patients. Copyright © 2017 The Authors. Published by Wolters Kluwer Health, Inc. All rights reserved.

  16. Detecting crop population growth using chlorophyll fluorescence imaging.

    Science.gov (United States)

    Wang, Heng; Qian, Xiangjie; Zhang, Lan; Xu, Sailong; Li, Haifeng; Xia, Xiaojian; Dai, Liankui; Xu, Liang; Yu, Jingquan; Liu, Xu

    2017-12-10

    For both field and greenhouse crops, it is challenging to evaluate their growth information on a large area over a long time. In this work, we developed a chlorophyll fluorescence imaging-based system for crop population growth information detection. Modular design was used to make the system provide high-intensity uniform illumination. This system can perform modulated chlorophyll fluorescence induction kinetics measurement and chlorophyll fluorescence parameter imaging over a large area of up to 45  cm×34  cm. The system can provide different lighting intensity by modulating the duty cycle of its control signal. Results of continuous monitoring of cucumbers in nitrogen deficiency show the system can reduce the judge error of crop physiological status and improve monitoring efficiency. Meanwhile, the system is promising in high throughput application scenarios.

  17. Change in the reaction kinetics of the deepoxidation of violaxanthine and activity of the xanthophyll ring under the action of γ irradiation

    International Nuclear Information System (INIS)

    Saakov, V.S.

    1993-01-01

    This article presents results of a study on the change in the content of the major chloroplast pigments and the activity of the xanthophyll ring as a function of irradiation dose. The data show that photodecomposition of chlorophyll and carotenoids is not associated with the primary action of ionizing radiations but may be manifested as a secondary process which follows inactivation or decomposition of the reaction center. Ionizing radiation affects the activity of the xanthophyll ring, as measured by deepoxidation of violaxanthine (DEV). Disruption of the electron transport chain leads to inhibition of DEV

  18. Optimal leaf positions for chlorophyll meter measurement in rice

    Directory of Open Access Journals (Sweden)

    Zhaofeng eYuan

    2016-05-01

    Full Text Available The Soil Plant Analysis Development (SPAD chlorophyll meter is one of the most commonly used diagnostic tools to measure crop nitrogen status. However, the measurement method of the meter could significantly affect the accuracy of the final estimation. Thus, this research was undertaken to develop a new methodology to optimize SPAD meter measurements in rice (Oryza sativa L.. A flatbed color scanner was used to map the dynamic chlorophyll distribution and irregular leaf shapes. Calculus algorithm was adopted to estimate the potential positions for SPAD meter measurement along the leaf blade. Data generated by the flatbed color scanner and SPAD meter were analysed simultaneously. The results suggested that a position 2/3 of the distance from the leaf base to the apex (2/3 position could represent the chlorophyll content of the entire leaf blade, as indicated by the relatively low variance of measurements at that positon. SPAD values based on di-positional leaves and the extracted chlorophyll a and b contents were compared. This comparison showed that the 2/3 position on the lower leaves tended to be more sensitive to changes in chlorophyll content. Finally, the 2/3 position and average SPAD values of the fourth fully expanded leaf from the top were compared with leaf nitrogen concentration. The results showed the 2/3 position on that leaf was most suitable for predicting the nitrogen status of rice. Based on these results, we recommend making SPAD measurements at the 2/3 position on the fourth fully expanded leaf from the top. The coupling of dynamic chlorophyll distribution and irregular leaf shapes information can provide a promising approach for the calibration of SPAD meter measurement, which can further benefit the in situ nitrogen management by providing reliable estimation of crops nitrogen nutrition status.

  19. Investigating the Control of Chlorophyll Degradation by Genomic Correlation Mining.

    Science.gov (United States)

    Ghandchi, Frederick P; Caetano-Anolles, Gustavo; Clough, Steven J; Ort, Donald R

    2016-01-01

    Chlorophyll degradation is an intricate process that is critical in a variety of plant tissues at different times during the plant life cycle. Many of the photoactive chlorophyll degradation intermediates are exceptionally cytotoxic necessitating that the pathway be carefully coordinated and regulated. The primary regulatory step in the chlorophyll degradation pathway involves the enzyme pheophorbide a oxygenase (PAO), which oxidizes the chlorophyll intermediate pheophorbide a, that is eventually converted to non-fluorescent chlorophyll catabolites. There is evidence that PAO is differentially regulated across different environmental and developmental conditions with both transcriptional and post-transcriptional components, but the involved regulatory elements are uncertain or unknown. We hypothesized that transcription factors modulate PAO expression across different environmental conditions, such as cold and drought, as well as during developmental transitions to leaf senescence and maturation of green seeds. To test these hypotheses, several sets of Arabidopsis genomic and bioinformatic experiments were investigated and re-analyzed using computational approaches. PAO expression was compared across varied environmental conditions in the three separate datasets using regression modeling and correlation mining to identify gene elements co-expressed with PAO. Their functions were investigated as candidate upstream transcription factors or other regulatory elements that may regulate PAO expression. PAO transcript expression was found to be significantly up-regulated in warm conditions, during leaf senescence, and in drought conditions, and in all three conditions significantly positively correlated with expression of transcription factor Arabidopsis thaliana activating factor 1 (ATAF1), suggesting that ATAF1 is triggered in the plant response to these processes or abiotic stresses and in result up-regulates PAO expression. The proposed regulatory network includes the

  20. Continuous excitation chlorophyll fluorescence parameters: a review for practitioners.

    Science.gov (United States)

    Banks, Jonathan M

    2017-08-01

    This review introduces, defines and critically reviews a number of chlorophyll fluorescence parameters with specific reference to those derived from continuous excitation chlorophyll fluorescence. A number of common issues and criticisms are addressed. The parameters fluorescence origin (F0) and the performance indices (PI) are discussed as examples. This review attempts to unify definitions for the wide range of parameters available for measuring plant vitality, facilitating their calculation and use. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  1. The C21-formyl group in chlorophyll f originates from molecular oxygen.

    Science.gov (United States)

    Garg, Harsh; Loughlin, Patrick C; Willows, Robert D; Chen, Min

    2017-11-24

    Chlorophylls (Chls) are the most important cofactors for capturing solar energy to drive photosynthetic reactions. Five spectral types of Chls have been identified to date, with Chl f having the most red-shifted absorption maximum because of a C2 1 -formyl group substitution of Chl f However, the biochemical provenance of this formyl group is unknown. Here, we used a stable isotope labeling technique ( 18 O and 2 H) to determine the origin of the C2 1 -formyl group of Chl f and to verify whether Chl f is synthesized from Chl a in the cyanobacterial species Halomicronema hongdechloris. In the presence of either H 2 18 O or 18 O 2 , the origin of oxygen atoms in the newly synthesized chlorophylls was investigated. The pigments were isolated with HPLC, followed by MS analysis. We found that the oxygen atom of the C2 1 -formyl group originates from molecular oxygen and not from H 2 O. Moreover, we examined the kinetics of the labeling of Chl a and Chl f from H. hongdechloris grown in 50% D 2 O-seawater medium under different light conditions. When cells were shifted from white light D 2 O-seawater medium to far-red light H 2 O-seawater medium, the observed deuteration in Chl f indicated that Chl(ide) a is the precursor of Chl f Taken together, our results advance our understanding of the biosynthesis pathway of the chlorophylls and the formation of the formyl group in Chl f . © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  2. Quick-Reaction Report on the Audit of Defense Base Realignment and Closure Budget Data for Naval Training Center Great Lakes, Illinois

    National Research Council Canada - National Science Library

    Granetto, Paul

    1994-01-01

    .... The Hull Technician School will share building 520 with the Advanced Hull Technician School, which is being realigned from the Naval Training Center San Diego, California, under project P-608T...

  3. The magnesium chelation step in chlorophyll biosynthesis. Progress report 1993

    Energy Technology Data Exchange (ETDEWEB)

    Weinstein, J.D.

    1993-12-31

    Progress is reported on the identification and fractionation of Magnesium chealatase, an enzyme involved in addition of Mg to chlorophyll during the later`s biosynthesis. Progress is documented as a series of synopsis of published and unpublished papers by the author.

  4. Influence of vermicompost humic acid on chlorophyll content and ...

    African Journals Online (AJOL)

    Influence of vermicompost humic acid on chlorophyll content and acclimatization in banana clone, Enano Guantanamero. Marcia Beatriz Moya Fernández, Esteban Sánchez Chávez, Daniel Cabezas Montero, Andrés Calderín García, Dany Marrero López, Eduardo F. Héctor Ardisana, Sandra Pérez Álvarez ...

  5. Improved ocean chlorophyll estimate from remote sensed data: The ...

    African Journals Online (AJOL)

    Gregg and Conkright (2001) who pioneered the use of the blending technique in an attempt to calibrate ocean chlorophyll, expressed the need for further work to be done in order to obtain improved results. One problem faced when using this technique with spatially sparse data, is distortion of the resulting blended field ...

  6. Identification and classification of vertical chlorophyll patterns in the ...

    African Journals Online (AJOL)

    A type of artificial neural network called a self-organizing map (SOM) was then used on these four parameters to identify characteristic profiles. The analysis identified a continuum of chlorophyll patterns, from those with large surface peaks (>10 mg m-3) to those with smaller near-surface peaks (<2 mg m-3). The frequency of ...

  7. Enzyme-assisted extraction of stabilized chlorophyll from spinach.

    Science.gov (United States)

    Özkan, Gülay; Ersus Bilek, Seda

    2015-06-01

    Zinc complex formation with chlorophyll derivatives in spinach pulp was studied by adding 300ppm Zn(2+) for production of stable food colorant, followed by the heating at 110°C for 15min. Zinc complex formation increased at pH values of 7.0 or greater. Pectinex Ultra SP-L was selected for enzyme-assisted release of zinc-chlorophyll derivatives from spinach pulp. Effect of enzyme concentration (1-9%), treatment temperature (30-60°C), and time (30-210min) on total chlorophyll content (TCC) were optimized using response surface methodology. A quadratic regression model (R(2)=0.9486) was obtained from the experimental design. Optimum treatment conditions were 8% enzyme concentration, 45°C, and 30min, which yielded a 50.747mgTCC/100g spinach pulp. Enzymatic treatment was followed by solvent extraction with ethanol at a solvent-to-sample ratio of 2.5:1 at 60°C for 45min for the highest TCC recovery. Pretreatment with enzyme and extraction in ethanol resulted in 39% increase in Zn-chlorophyll derivative yield. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. Validation of OCM-2 sensor performance in retrieving chlorophyll ...

    Indian Academy of Sciences (India)

    Ocean colour; chlorophyll a; total suspended matter; validation; Bay of Bengal; OCM-2. J. Earth Syst. Sci. 122 ... two basins, the Arabian Sea and Bay of Bengal. (BoB). Arabian ... The capability of visible bands of multi-spectral satellite data has ...

  9. Application of a chlorophyll index derived from satellite data to ...

    African Journals Online (AJOL)

    Application of a chlorophyll index derived from satellite data to investigate the variability of phytoplankton in the Benguela ecosystem. H Demarcq, R Barlow, L Hutchings. Abstract. No Abstract. African Journal of Marine Science Vol.29(2) 2007: pp. 271-282. Full Text: EMAIL FULL TEXT EMAIL FULL TEXT · DOWNLOAD ...

  10. Effect of temperature on accumulation of chlorophylls and leaf ...

    African Journals Online (AJOL)

    White young shoots from albino tea cultivars have high level of amino acids and are rare and valuable materials for processing green tea. The effects of temperature on leaf colour, accumulation of chlorophylls and leaf ultrastructures of an albino tea cultivar 'Xiaxueya' were investigated. The study showed that the shoot ...

  11. Chlorophyll, nitrogen and antioxidant activities in Cumaru ( Dipteryx ...

    African Journals Online (AJOL)

    ... by traditional populations and industries using timber and non-timber forest products. This study aimed to analyze the levels of chlorophyll A, B, total ammonia levels, nitrate, proline, electrolyte leakage and activity of oxidative enzymes in evaluation to tolerance of cumaru plants subjected to drought for 21 days of stress.

  12. Using chlorophyll fluorescence to determine stress in Eucalyptus ...

    African Journals Online (AJOL)

    Using chlorophyll fluorescence to determine stress in Eucalyptus grandis seedlings: scientific paper. ... Southern Forests: a Journal of Forest Science ... factors affect the functioning of the photosynthetic system, the status of the photosynthetic apparatus is a good indicator of the plant in terms of stress and stress adaptation.

  13. Chlorophyll Fluorescence Imaging Uncovers Photosynthetic Fingerprint of Citrus Huanglongbing

    Directory of Open Access Journals (Sweden)

    Haiyan Cen

    2017-08-01

    Full Text Available Huanglongbing (HLB is one of the most destructive diseases of citrus, which has posed a serious threat to the global citrus production. This research was aimed to explore the use of chlorophyll fluorescence imaging combined with feature selection to characterize and detect the HLB disease. Chlorophyll fluorescence images of citrus leaf samples were measured by an in-house chlorophyll fluorescence imaging system. The commonly used chlorophyll fluorescence parameters provided the first screening of HLB disease. To further explore the photosynthetic fingerprint of HLB infected leaves, three feature selection methods combined with the supervised classifiers were employed to identify the unique fluorescence signature of HLB and perform the three-class classification (i.e., healthy, HLB infected, and nutrient deficient leaves. Unlike the commonly used fluorescence parameters, this novel data-driven approach by using the combination of the mean fluorescence parameters and image features gave the best classification performance with the accuracy of 97%, and presented a better interpretation for the spatial heterogeneity of photochemical and non-photochemical components in HLB infected citrus leaves. These results imply the potential of the proposed approach for the citrus HLB disease diagnosis, and also provide a valuable insight for the photosynthetic response to the HLB disease.

  14. Mahalanobis distance screening of Arabidopsis mutants with chlorophyll fluorescence

    Czech Academy of Sciences Publication Activity Database

    Codrea, C. C.; Hakala-Yatkin, M.; Karlund-Marttila, A.; Nedbal, Ladislav; Aittokallio, T.; Nevalainen, O. S.; Tyystjärvi, E.

    2010-01-01

    Roč. 105, č. 3 (2010), s. 273-283 ISSN 0166-8595 Institutional research plan: CEZ:AV0Z60870520 Keywords : arabidopsis thaliana * chlorophyll fluorescence * fluorescence imaging * mutant detection * outlier detection Subject RIV: EH - Ecology, Behaviour Impact factor: 2.410, year: 2010 http://www.springerlink.com/content/x3586512462pn006/

  15. Effect of organic and inorganic fertilizer on yield and chlorophyll ...

    African Journals Online (AJOL)

    The effects of amending soil with organic (poultry manure) and inorganic fertilizer on yield and chlorophyll content of maize (Zea mays L.) and sorghum (Sorghum bicolour (L.) Moench) was carried out at the Teaching and Research (T&R) Farm of the Obafemi Awolowo University, (O.A.U.) Ile - Ife, Nigeria. The experiment ...

  16. Chlorophyll meter reading and total nitrogen content applied as ...

    African Journals Online (AJOL)

    The present study was aimed to assess the relationship between the reading of the chlorophyll meter and the total nitrogen (N) content in the leaf in different parts of the crambe plant, depending on the doses of nitrogen applied to the canopy. Randomized block design in a split plot experimental design was used. The plots ...

  17. Global NOAA CoastWatch Chlorophyll Frontal Product from MODIS/Aqua (NCEI Accession 0110333)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — MODIS/Aqua chlorophyll frontal products: the NOAA Okeanos operational production system produces near real-time chlorophyll frontal products (magnitude and...

  18. Ocean Chlorophyll as a Precursor of ENSO: An Earth System Modeling Study

    Science.gov (United States)

    Park, Jong-Yeon; Dunne, John P.; Stock, Charles A.

    2018-02-01

    Ocean chlorophyll concentration, a proxy for phytoplankton, is strongly influenced by internal ocean dynamics such as those associated with El Niño-Southern Oscillation (ENSO). Observations show that ocean chlorophyll responses to ENSO generally lead sea surface temperature (SST) responses in the equatorial Pacific. A long-term global Earth system model simulation incorporating marine biogeochemical processes also exhibits a preceding chlorophyll response. In contrast to simulated SST anomalies, which significantly lag the wind-driven subsurface heat response to ENSO, chlorophyll anomalies respond rapidly. Iron was found to be the key factor connecting the simulated surface chlorophyll anomalies to the subsurface ocean response. Westerly wind bursts decrease central Pacific chlorophyll by reducing iron supply through wind-driven thermocline deepening but increase western Pacific chlorophyll by enhancing the influx of coastal iron from the maritime continent. Our results mechanistically support the potential for chlorophyll-based indices to inform seasonal ENSO forecasts beyond previously identified SST-based indices.

  19. The effect of acid rain stress on chlorophyll, peroxidase of the conservation of rare earth elements

    International Nuclear Information System (INIS)

    Chongling, Y.; Yetang, H.; Xianke, Y.; Shunzhen, F.; Shanql, W.

    1998-01-01

    Full text: Based on pot experiment, the effect of acid rain stress on chlorophyll, peroxidase of wheat, the relationship of them and the conservation of rare earth elements has been studied. The result showed: stress of acid rain resulted in decrease of chlorophyll content and a/b values, chlorophyll a/b value and chlorophyll content is positive correlation with pH value of acid rain: peroxidase activity was gradually rise with pH value decrease, which indirectly increased decomposition intensity of chlorophyll. Decreased content and a/b value of chlorophyll further speeded blade decay affected the transport and transformation of light energy and metabolism of carbohydrates. After being treated by rare earth elements content and pH value of chlorophyll and peroxidase activity could be relatively stable. Therefore, under lower acidity condition, rare earth elements can influence the effect of acid rain on chlorophyll and peroxidase activity of wheat

  20. Lead pollution: effects on chlorophyll. [Phalaris canariensis, Lemna minor, graminaceae

    Energy Technology Data Exchange (ETDEWEB)

    Fiussello, N

    1973-01-01

    The emissions of motors are responsible for the high concentrations of lead in soil and plants near roads. In man, when the concentration of lead in blood exceeds the value of 30 ..mu..g/100 ml, is shown a decrease of haemaglobin and an increase of ALA urinary content. Since the early stages of chlorophyll biosynthetic pathway are similar if not identical with those leading to haem as far as protoporphyrin IX, it is interesting to ascertain if lead can specifically interfere in chlorophyll biosynthesis. In sand cultures with 200 p.p.m. of lead (the conc. in roadside soils), after 2 weeks, wheat shows a diminution of 16,5% in fresh weight 7,5% in dry weight and 6,5% in chlorophyll; Phalaris canariensis shows a diminution of 68% f.w., 41% d.w. and 39% chl. in comparison with the controls. A water-plant, Lemna minor, is more sensitive: the chlorophyll content, referred to dry weight, shows after a week a diminution of 32% and 55% with 10/sup -4/M and 10/sup -3/M lead nitrate. Lead in 200 p.p.m. conc. is surely poisonous against the tested plants but a specific action on chlorophyll synthesis could be accepted, at present, only for Lemna minor. It is possible that in wheat and in Phalaris a part of lead is bound in root-system, the more damaged, while in Lemna it can reach more easily the chloroplasts. At present a detectable increase of ALA, in plants treated with lead, has not been proved both in Graminaceae and in Lemna minor.

  1. Petasis/Diels-Alder/Cyclization Cascade Reactions for the Generation of Scaffolds with Multiple Stereogenic Centers and Orthogonal Handles for Library Production

    DEFF Research Database (Denmark)

    Flagstad, Thomas; Azevedo, Carlos M. G.; Min, Geanna

    2018-01-01

    A new effective strategy for the synthesis of sp3‐rich small molecules for library production is presented. The key steps to generate complexity highlight Petasis 3‐component reaction followed by an intramolecular Diels‐Alder and cyclization to generate a densely enriched tricyclic or tetracyclic...

  2. Kinetic studies on the reaction of cob(II)alamin with hypochlorous acid: Evidence for one electron oxidation of the metal center and corrin ring destruction.

    Science.gov (United States)

    Dassanayake, Rohan S; Farhath, Mohamed M; Shelley, Jacob T; Basu, Soumitra; Brasch, Nicola E

    2016-10-01

    Kinetic and mechanistic studies on the reaction of a major intracellular vitamin B 12 form, cob(II)alamin (Cbl(II)), with hypochlorous acid/hypochlorite (HOCl/OCl - ) have been carried out. Cbl(II) (Co(II)) is rapidly oxidized by HOCl to predominately aquacobalamin/hydroxycobalamin (Cbl(III), Co(III)) with a second-order rate constant of 2.4×10 7 M -1 s -1 (25.0°C). The stoichiometry of the reaction is 1:1. UHPLC/HRMS analysis of the product mixture of the reaction of Cbl(II) with 0.9mol equiv. HOCl provides support for HOCl being initially reduced to Cl and subsequent H atom abstraction from the corrin macrocycle occurring, resulting in small amounts of corrinoid species with two or four H atoms fewer than the parent cobalamin. Upon the addition of excess (H)OCl further slower reactions are observed. Finally, SDS-PAGE experiments show that HOCl-induced damage to bovine serum albumin does not occur in the presence of Cbl(II), providing support for Cbl(II) being an efficient HOCl trapping agent. Copyright © 2016 Elsevier Inc. All rights reserved.

  3. Quick-Reaction Report on the Audit of Defense Base Realignment and Closure Budget Data for Naval Training Center Great Lakes, Illinois

    Science.gov (United States)

    1994-05-19

    the audit of project P-608T, Building Modifications, as they relate to project P-557S. Because...project P-608T was addressed in Report No. 94-108, Quick-Reaction Report on the Audit of Defense Base Realignment and Closure Budget Data for Naval Station Treasure Island, California, May 19,

  4. Volume changes and electrostriction in the primary photoreactions of various photosynthetic systems: estimation of dielectric coefficient in bacterial reaction centers and of the observed volume changes with the Drude-Nernst equation.

    Science.gov (United States)

    Mauzerall, David; Hou, Jian-Min; Boichenko, Vladimir A

    2002-01-01

    Photoacoustics (PA) allows the determination of enthalpy and volume changes of photoreactions in photosynthetic reaction centers on the 0.1-10 mus time scale. These include the bacterial centers from Rb. sphaeroides, PS I and PS II centers from Synechocystis and in whole cells. In vitro and in vivo PA data on PS I and PS II revealed that both the volume change (-26 A(3)) and reaction enthalpy (-0.4 eV) in PS I are the same as those in the bacterial centers. However the volume change in PS II is small and the enthalpy far larger, -1 eV. Assigning the volume changes to electrostriction allows a coherent explanation of these observations. One can explain the large volume decrease in the bacterial centers with an effective dielectric coefficient of approximately 4. This is a unique approach to this parameter so important in estimation of protein energetics. The value of the volume contraction for PS I can only be explained if the acceptor is the super- cluster (Fe(4)S(4))(Cys(4)) with charge change from -1 to -2. The small volume change in PS II is explained by sub-mus electron transfer from Y(Z) anion to P(680) cation, in which charge is only moved from the Y(Z) anion to the Q(A) with no charge separation or with rapid proton transfer from oxidized Y(Z) to a polar region and thus very little change in electrostriction. At more acid pH equally rapid proton transfer from a neighboring histidine to a polar region may be caused by the electric field of the P(680) cation.

  5. Chlorophyll Meters Aid Plant Nutrient Management

    Science.gov (United States)

    2009-01-01

    On December 7, 1972, roughly 5 hours and 6 minutes after launch, the crew of Apollo 17 took one of history s most famous photographs. The brilliant image of the fully illuminated Earth, the African and Antarctic continents peering out from behind swirling clouds, came to be known as the Blue Marble. Today, Earth still sometimes goes by the Blue Marble nickname, but as the satellites comprising NASA s Earth Observing System (EOS) scan the planet daily in ever greater resolutions, it is often the amount of green on the planet that is a focus of researchers attention. Earth s over 400,000 known plant species play essential roles in the planet s health: They absorb carbon dioxide and release the oxygen we breathe, help manage the Earth s temperature by absorbing and reflecting sunlight, provide food and habitats for animals, and offer building materials, medication, and sustenance for humans. As part of NASA s efforts to study our own planet along with the universe around it, the Agency s EOS satellites have been accumulating years of valuable data about Earth s vegetation (not to mention its land features, oceans, and atmosphere) since the first EOS satellite launched in 1997. Among the powerful sensors used is the Moderate Resolution Imaging Spectroradiometer (MODIS) on board the NASA Terra and Aqua satellites. MODIS sweeps the entire Earth every few days, beaming back information gathered across 36 bands of visible and infrared light, yielding images that let scientists track how much of Earth is green over the course of seasons and years. Monitoring the density and distribution of vegetation on Earth provides a means of determining everything from the impact of natural and human-induced climate change to the potential outbreak of disease. (Goddard Space Flight Center and U.S. Department of Defense researchers have determined, for example, that vegetation density can be used to pinpoint regions of heavy rainfall in Africa regions ripe for outbreaks of rainfall

  6. Portable chlorophyll meter (PCM-502) values are related to total chlorophyll concentration and photosynthetic capacity in papaya (Carica papaya L.)

    Science.gov (United States)

    This study was carried out to verify the practical use of the portable chlorophyll meter-PCM502 (PCM) in two papaya cultivars with contrasting green coloring of the leaf blade (‘Golden’: yellowish-green; ‘Solo’: dark green). The relationship was studied between the photosynthetic process and leaf n...

  7. Effect of automobile pollution on chlorophyll content of roadside urban trees

    Directory of Open Access Journals (Sweden)

    M. Iqbal

    2015-09-01

    Full Text Available The effect of automobile pollution was determined on chlorophyll content of four different tree species viz. Azadirachta indica L., Conocarpus erectus L., Guiacum officinale L.and Eucalyptus sp. growing along the roads of the city.  Significant changes in the level of chlorophyll “a”, chlorophyll “b” and total chlorophyll “a+b” were found in the leaves of four tree species (A. indica, C. erectus, G.officinale and Eucalyptus sp. collected from polluted sites (Airport, Malir Halt, Quaidabad as compared to control site (Karachi University Campus. Lowest concentration of chlorophyll “a”, chlorophyll “b” and chlorophyll “a+b” was recorded in the leaf samples of all tree species collected from Quaidabad site when compared with the leaf samples collected from control site. The highest levels of chlorophyll pigment were recorded in all tree species leave samples collected from Karachi University Campus.  Similarly, better levels of chlorophyll “a”, chlorophyll “b” and total chlorophyll “a+b” was observed in all tree species growing at Airport site as compared to plants growing at Malir Halt and Quaidabad sites.  This study clearly indicated that the vehicular activities induced air pollution problem and affected on the level of chlorophyll pigments in trees which were exposed to road side pollution.

  8. Integrating Biology into the General Chemistry Laboratory: Fluorometric Analysis of Chlorophyll "a"

    Science.gov (United States)

    Wesolowski, Meredith C.

    2014-01-01

    A laboratory experiment that introduces fluorometry of chlorophyll "a" at the general chemistry level is described. The use of thin-layer chromatography to isolate chlorophyll "a" from spirulina and leaf matter enables quantification of small amounts of chlorophyll "a" via fluorometry. Student results were reasonably…

  9. Two-photon excited fluorescence from higher electronic states of chlorophylls in photosynthetic antenna complexes a new approach to detect strong excitonic chlorophyll a/b coupling

    CERN Document Server

    Leupold, D; Ehlert, J; Irrgang, K D; Renger, G; Lokstein, H

    2002-01-01

    Stepwise two-photon excitation of chlorophyll a and b in the higher plant main light-harvesting complex (LHC II) and the minor complex CP29 (as well as in organic solution) with 100-fs pulses in the Q/sub y/ region results in a weak blue fluorescence. The dependence of the spectral shape of the blue fluorescence on excitation wavelength offers a new approach to elucidate the long-standing problem of the origin of spectral "chlorophyll forms" in pigment-protein complexes, in particular the characterization of chlorophyll a/b-heterodimers. As a first result we present evidence for the existence of strong chlorophyll a/b-interactions (excitonically coupled transitions at 650 and 680 nm) in LHC II at ambient temperature. In comparison with LHC II, the experiments with CP29 provide further evidence that the lowest energy chlorophyll a transition (at ~680 nm) is not excitonically coupled to chlorophyll b. (22 refs).

  10. Selected ion flow tube (SIFT) studies of the reactions of H3O+, NO+ and O-2(+center dot) with six volatile phytogenic esters

    Czech Academy of Sciences Publication Activity Database

    Sovová, K.; Dryahina, Kseniya; Španěl, Patrik

    2011-01-01

    Roč. 300, č. 1 (2011), s. 31-38 ISSN 1387-3806 R&D Projects: GA ČR GA202/09/0800; GA ČR GA203/09/0256 Institutional research plan: CEZ:AV0Z40400503 Keywords : SIFT-MS * ion-molecule reactions * plant esters Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.549, year: 2011

  11. Effects of space environment on chlorophyll fluorescence and photosynthesis characteristics of wheat

    International Nuclear Information System (INIS)

    Lu Li; Lv Jinyin; Gong Qingzhu; Gao Junfeng

    2006-01-01

    The effects of the space environment on the chlorophyll fluorescence parameters and photosynthesis characteristics of wheat cultivars, Xinong 1043 M1 and Shaan253 M 1 , were studied. The results showed that the decrement of contents of PS II primary photochemical efficiency (F v /F m ), potential activity (F v /F 0 ), photochemical quenching coefficient (qP) and photosynthesis rate (Pn) were less than that of control, increment of non-photochemical quenching coefficient (qN) were more than that of control. The results suggested that photosynthetic apparatus were damaged, photosynthetic electron transport, photosynthetic primary reaction were inhibited, rate of photosynthesis decreased and growth of M 1 plant were retarded, which leading to thousand kernel weights decreased. (authors)

  12. Efficient Destruction of Pollutants in Water by a Dual-Reaction-Center Fenton-like Process over Carbon Nitride Compounds-Complexed Cu(II)-CuAlO2.

    Science.gov (United States)

    Lyu, Lai; Yan, Dengbiao; Yu, Guangfei; Cao, Wenrui; Hu, Chun

    2018-04-03

    Carbon nitride compounds (CN) complexed with the in-situ-produced Cu(II) on the surface of CuAlO 2 substrate (CN-Cu(II)-CuAlO 2 ) is prepared via a surface growth process for the first time and exhibits exceptionally high activity and efficiency for the degradation of the refractory pollutants in water through a Fenton-like process in a wide pH range. The reaction rate for bisphenol A removal is ∼25 times higher than that of the CuAlO 2 . According to the characterization, Cu(II) generation on the surface of CuAlO 2 during the surface growth process results in the marked decrease of the surface oxygen vacancies and the formation of the C-O-Cu bridges between CN and Cu(II)-CuAlO 2 in the catalyst. The electron paramagnetic resonance (EPR) analysis and density functional theory (DFT) calculations demonstrate that the dual reaction centers are produced around the Cu and C sites due to the cation-π interactions through the C-O-Cu bridges in CN-Cu(II)-CuAlO 2 . During the Fenton-like reactions, the electron-rich center around Cu is responsible for the efficient reduction of H 2 O 2 to • OH, and the electron-poor center around C captures electrons from H 2 O 2 or pollutants and diverts them to the electron-rich area via the C-O-Cu bridge. Thus, the catalyst exhibits excellent catalytic performance for the refractory pollutant degradation. This study can deepen our understanding on the enhanced Fenton reactivity for water purification through functionalizing with organic solid-phase ligands on the catalyst surface.

  13. Synthesis of methyl (13(2)R/S)-alkyl-pyropheophorbide a and a non-epimerized chlorophyll a mimic.

    Science.gov (United States)

    Ogasawara, Shin; Tamiaki, Hitoshi

    2015-10-15

    The (13(2)R/S)-methoxycarbonyl group of methyl pheophorbides a/a' (chlorophyll a/a' derivatives) was converted to methyl, ethyl, propyl, and isopropyl groups through the C13(2)-alkylation under basic conditions followed by pyrolysis in 2,4,6-collidine with lithium iodide. All the resulting products, methyl 13(2)-alkyl-pyropheophorbides a, predominantly gave the (13(2)R)-stereoisomers with about one tenth of the (13(2)S)-epimers. Their stereochemistry was determined by 1D/2D NMR and their optical properties were characterized by visible absorption and circular dichroism spectroscopy. Methyl (13(2)R)-propyl-pyropheophorbide a was converted to (13(2)R)-propyl-pyrochlorophyll a by ester exchanging and magnesium chelating reactions. The synthetic chlorophyll a analogue showed non-epimerization at the 13(2)-position in pyridine-d5 at 40°C, while naturally occurring chlorophyll a was easily epimerized under the same conditions to give its epimeric mixture. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. How diffusivity, thermocline and incident light intensity modulate the dynamics of deep chlorophyll maximum in Tyrrhenian Sea.

    Directory of Open Access Journals (Sweden)

    Davide Valenti

    Full Text Available During the last few years theoretical works have shed new light and proposed new hypotheses on the mechanisms which regulate the spatio-temporal behaviour of phytoplankton communities in marine pelagic ecosystems. Despite this, relevant physical and biological issues, such as effects of the time-dependent mixing in the upper layer, competition between groups, and dynamics of non-stationary deep chlorophyll maxima, are still open questions. In this work, we analyze the spatio-temporal behaviour of five phytoplankton populations in a real marine ecosystem by using a one-dimensional reaction-diffusion-taxis model. The study is performed, taking into account the seasonal variations of environmental variables, such as light intensity, thickness of upper mixed layer and profiles of vertical turbulent diffusivity, obtained starting from experimental findings. Theoretical distributions of phytoplankton cell concentration was converted in chlorophyll concentration, and compared with the experimental profiles measured in a site of the Tyrrhenian Sea at four different times (seasons of the year, during four different oceanographic cruises. As a result we find a good agreement between theoretical and experimental distributions of chlorophyll concentration. In particular, theoretical results reveal that the seasonal changes of environmental variables play a key role in the phytoplankton distribution and determine the properties of the deep chlorophyll maximum. This study could be extended to other marine ecosystems to predict future changes in the phytoplankton biomass due to global warming, in view of devising strategies to prevent the decline of the primary production and the consequent decrease of fish species.

  15. Cylindrical aggregates of chlorophylls studied by small-angle neutron scatter

    Energy Technology Data Exchange (ETDEWEB)

    Worcester, D.L. [Univ. of Missouri, Columbus, MO (United States); Katz, J.J. [Argonne National Laboratory, IL (United States)

    1994-12-31

    Neutron small-angle scattering has demonstrated tubular chlorophyll aggregates formed by self-assembly of a variety of chlorophyll types in nonpolar solvents. The size and other properties of the tubular aggregates can be accounted for by stereochemical properties of the chlorophyll molecules. Features of some of the structures are remarkably similar to light harvesting chlorophyll complexes in vivo, particularly for photosynthetic bacteria. These nanotube chlorophyll structures may have applications as light harvesting biomaterials where efficient energy transfer occurs from an excited state which is highly delocalized.

  16. Multifractal analysis of oceanic chlorophyll maps remotely sensed from space

    Directory of Open Access Journals (Sweden)

    L. de Montera

    2011-03-01

    Full Text Available Phytoplankton patchiness has been investigated with multifractal analysis techniques. We analyzed oceanic chlorophyll maps, measured by the SeaWiFS orbiting sensor, which are considered to be good proxies for phytoplankton. The study area is the Senegalo-Mauritanian upwelling region, because it has a low cloud cover and high chlorophyll concentrations. Multifractal properties are observed, from the sub-mesoscale up to the mesoscale, and are found to be consistent with the Corssin-Obukhov scale law of passive scalars. This result indicates that, in this specific region and within this scale range, turbulent mixing would be the dominant effect leading to the observed variability of phytoplankton fields. Finally, it is shown that multifractal patchiness can be responsible for significant biases in the nonlinear source and sink terms involved in biogeochemical numerical models.

  17. Regional variability among nonlinear chlorophyll-phosphorus relationships in lakes

    Science.gov (United States)

    Filstrup, Christopher T.; Wagner, Tyler; Soranno, Patricia A.; Stanley, Emily H.; Stow, Craig A.; Webster, Katherine E.; Downing, John A.

    2014-01-01

    The relationship between chlorophyll a (Chl a) and total phosphorus (TP) is a fundamental relationship in lakes that reflects multiple aspects of ecosystem function and is also used in the regulation and management of inland waters. The exact form of this relationship has substantial implications on its meaning and its use. We assembled a spatially extensive data set to examine whether nonlinear models are a better fit for Chl a—TP relationships than traditional log-linear models, whether there were regional differences in the form of the relationships, and, if so, which regional factors were related to these differences. We analyzed a data set from 2105 temperate lakes across 35 ecoregions by fitting and comparing two different nonlinear models and one log-linear model. The two nonlinear models fit the data better than the log-linear model. In addition, the parameters for the best-fitting model varied among regions: the maximum and lower Chl aasymptotes were positively and negatively related to percent regional pasture land use, respectively, and the rate at which chlorophyll increased with TP was negatively related to percent regional wetland cover. Lakes in regions with more pasture fields had higher maximum chlorophyll concentrations at high TP concentrations but lower minimum chlorophyll concentrations at low TP concentrations. Lakes in regions with less wetland cover showed a steeper Chl a—TP relationship than wetland-rich regions. Interpretation of Chl a—TP relationships depends on regional differences, and theory and management based on a monolithic relationship may be inaccurate.

  18. [Vegetation index estimation by chlorophyll content of grassland based on spectral analysis].

    Science.gov (United States)

    Xiao, Han; Chen, Xiu-Wan; Yang, Zhen-Yu; Li, Huai-Yu; Zhu, Han

    2014-11-01

    Comparing the methods of existing remote sensing research on the estimation of chlorophyll content, the present paper confirms that the vegetation index is one of the most practical and popular research methods. In recent years, the increasingly serious problem of grassland degradation. This paper, firstly, analyzes the measured reflectance spectral curve and its first derivative curve in the grasslands of Songpan, Sichuan and Gongger, Inner Mongolia, conducts correlation analysis between these two spectral curves and chlorophyll content, and finds out the regulation between REP (red edge position) and grassland chlorophyll content, that is, the higher the chlorophyll content is, the higher the REIP (red-edge inflection point) value would be. Then, this paper constructs GCI (grassland chlorophyll index) and selects the most suitable band for retrieval. Finally, this paper calculates the GCI by the use of satellite hyperspectral image, conducts the verification and accuracy analysis of the calculation results compared with chlorophyll content data collected from field of twice experiments. The result shows that for grassland chlorophyll content, GCI has stronger sensitivity than other indices of chlorophyll, and has higher estimation accuracy. GCI is the first proposed to estimate the grassland chlorophyll content, and has wide application potential for the remote sensing retrieval of grassland chlorophyll content. In addition, the grassland chlorophyll content estimation method based on remote sensing retrieval in this paper provides new research ideas for other vegetation biochemical parameters' estimation, vegetation growth status' evaluation and grassland ecological environment change's monitoring.

  19. Estimate of Leaf Chlorophyll and Nitrogen Content in Asian Pear (Pyrus serotina Rehd. by CCM-200

    Directory of Open Access Journals (Sweden)

    Mostafa GHASEMI

    2011-03-01

    Full Text Available In many cases evaluation of chlorophyll and nitrogen content in plants need to destructive methods, more time and organic solvents. Application of chlorophyll meters save time and resources. The aim of this study was estimating of chlorophyll and nitrogen content in Asian pear leaves using non-destructive method and rapid quantification of chlorophyll by chlorophyll content meter (CCM-200. This study was conducted on 8 years old Asian pear trees during June 2008 in Tehran, Iran. To develop our regression model, the chlorophyll meter data were correlated with extracted chlorophyll and nitrogen content data obtained from DMSO and Kejeldal methods, respectively. The results showed that, there was positive and linear correlation between CCM-200 data and chlorophyll a (R�=0.7183, chlorophyll b (R�=0.8523, total chlorophyll (R�=0.90, and total nitrogen content (R�=0.76 in Asian pear leaves. Thus, it can be concluded that, CCM-200 can be used in order to predict both chlorophyll and nitrogen content in Asian pear leaves.

  20. Workgroup Report by the Joint Task Force Involving American Academy of Allergy, Asthma & Immunology (AAAAI); Food Allergy, Anaphylaxis, Dermatology and Drug Allergy (FADDA) (Adverse Reactions to Foods Committee and Adverse Reactions to Drugs, Biologicals, and Latex Committee); and the Centers for Disease Control and Prevention Botulism Clinical Treatment Guidelines Workgroup-Allergic Reactions to Botulinum Antitoxin: A Systematic Review.

    Science.gov (United States)

    Schussler, Edith; Sobel, Jeremy; Hsu, Joy; Yu, Patricia; Meaney-Delman, Dana; Grammer, Leslie C; Nowak-Wegrzyn, Anna

    2017-12-27

    Naturally occurring botulism is rare, but a large number of cases could result from unintentional or intentional contamination of a commercial food. Despeciated, equine-derived, heptavalent botulinum antitoxin (HBAT) is licensed in the United States. Timely treatment reduces morbidity and mortality, but concerns that botulinum antitoxin can induce anaphylaxis exist. We sought to quantify the allergy risk of botulinum antitoxin treatment and the usefulness of skin testing to assess this risk. We conducted a systematic review of (1) allergic reactions to botulinum antitoxin and (2) the predictive value of skin testing (ST) before botulinum antitoxin administration. We searched 5 scientific literature databases, reviewed articles' references, and obtained data from the HBAT manufacturer and from the Centers for Disease Control and Prevention. Anaphylaxis incidence was determined for HBAT and previously employed botulinum antitoxins. We calculated the positive predictive value (PPV) and negative predictive value (NPV) of ST for anaphylaxis related to HBAT and other botulinum antitoxins. Seven articles were included. Anaphylaxis incidence was 1.64% (5/305 patients) for HBAT and 1.16% (8/687 patients) for all other botulinum antitoxins (relative risk, 1.41 [95% confidence interval, .47-4.27]; P = .5). Observed values for both PPV and NPV for HBAT-ST (33 patients) were 100%. Observed PPVs and NPVs of ST for other botulinum antitoxins (302 patients) were 0-56% and 50%-100%, respectively. There were no reports of fatal anaphylaxis. Considering the <2 % rate of anaphylaxis, fatal outcomes, modest predictive value of ST, resource requirements for ST, and the benefits of early treatment, data do not support delaying HBAT administration to perform ST in a mass botulinum toxin exposure. Anaphylactic reactions may occur among 1%-2% of botulinum antitoxin recipients and will require epinephrine and antihistamine treatment and, possibly, intensive care. Published by Oxford

  1. Effects of Dihydroartemisinin and Artemether on the Growth, Chlorophyll Fluorescence, and Extracellular Alkaline Phosphatase Activity of the Cyanobacterium Microcystis aeruginosa.

    Science.gov (United States)

    Wang, Shoubing; Xu, Ziran

    2016-01-01

    Increased eutrophication in the recent years has resulted in considerable research focus on identification of methods for preventing cyanobacterial blooms that are rapid and efficient. The objectives of this study were to investigate the effects of dihydroartemisinin and artemether on the growth of Microcystis aeruginosa and to elucidate its mode of action. Variations in cell density, chlorophyll a, soluble protein, malondialdehyde, extracellular alkaline phosphatase activity (APA), and chlorophyll fluorescence parameters (Fv/Fm, ΦPSII, ETR, rapid light curves, fast chlorophyll fluorescence curves on fluorescence intensity, and relative variable fluorescence) were evaluated by lab-cultured experiments. Our results demonstrated that both dihydroartemisinin and artemether inhibited the growth of M.aeruginosa by impairing the photosynthetic center in photosystem II and reducing extracellular APA, with a higher sensitivity exhibited toward artemether. The inhibitory effects of dihydroartemisinin on M.aeruginosa increased with concentration, and the maximum growth inhibitory rate was 42.17% at 24 mg·L-1 after 120h exposure, whereas it was 55.72% at 6 mg·L-1 artemetherafter 120h exposure. Moreover, the chlorophyll fluorescence was significantly inhibited (p<0.05) after 120h exposure to 12 and 24 mg·L-1 dihydroartemisinin. Furthermore, after 120h exposure to 6 mg·L-1 artemether, Fv/Fm, ΦPSII, ETR and rETRmax showed a significant decrease (p<0.01) from initial values of 0.490, 0.516, 17.333, and 104.800, respectively, to 0. One-way analysis of variance showed that 6 mg·L-1 artemether and 24 mg·L-1 dihydroartemisinin had significant inhibitory effects on extracellular APA (p<0.01). The results of this study would be useful to further studies to validate the feasibility of dihydroartemisinin and artemether treatment to inhibit overall cyanobacterial growth in water bodies, before this can be put into practice.

  2. Notes on the instability of extracted chlorophyll and a reported effect of ozone on lichen algae

    Energy Technology Data Exchange (ETDEWEB)

    Brown, D H

    1980-01-01

    Recently Rosentreter and Ahmadjian reported on the effects of ozone on the chlorophyll content of Cladonia arbuscula and isolated Trebouxia cells. However, the chlorophyll data they presented, even for the control, unozone-treated material, appears to be unusual. They reported values of the chlorophyll a/b ratio of 0.308-0.463 from Cladonia arbuscula and 0.345-0.476 for Trebouxia which are substantially lower than other published values. Because chlorophyll b is normally present in green plants as a minor accessory photosynthetic pigment, the suggestion that it was the major chlorophyll component requires some explanation. The purpose of this study is to show that chlorophyll is unstable when extracted into methanol and to suggest that the extraction and storage conditions used by Rosentreter and Ahmadjian may have allowed pigment degradation to occur which thereby accounted for the low chlorophyll a/b ratios they obtained.

  3. Gas exchange and chlorophyll a fluorescence parameters of ornamental bromeliads

    Directory of Open Access Journals (Sweden)

    Karina Gonçalves da Silva

    2017-10-01

    Full Text Available Gas exchange and chlorophyll a fluorescence are widely used in physiological and ecological studies; however, few studies have used these techniques with ornamental plants. This study tested the potential contribution of gas exchange and chlorophyll a fluorescence to evaluate the water and nutrients uptake by the tank and root system of epiphyte bromeliad Guzmania lingulata. For this purpose, we conducted an experiment with different water regime and another with different concentrations of nitrogen. The experiments were: 1 - Watering: Control (application of water into Tank and Root, Tank (watering into Tank, Root (watering Root and Drought (water suspension during the 90 days of experimentation and 2 - Nitrogen: Plants fertilized with Hoagland and Arnon nutrient solution exclusively into Tank or Root with nitrogen concentrations of control and 2.62 or 5.34 mM N applied as urea. The Fv /Fm ratio allowed comparing the treatments between experiments, demonstrating that Root and Tank both have the capacity to maintain G. lingulata photosynthetic activity and growth, while Drought treatment (water suspension was the limiting factor for energy conversion efficiency of PSII. However, gas exchange was more permissive as a parameter for comparing treatments in the nitrogen experiment, providing important information about the general aspects of the photosynthetic process in the watering experiment. Both gas exchange and chlorophyll a fluorescence can support the evaluation of G. lingulata physiological status and can be useful tools in ornamental horticultural studies.

  4. Individual members of the light-harvesting complex II chlorophyll a/b-binding protein gene family in pea (Pisum sativum) show differential responses to ultraviolet-B radiation

    International Nuclear Information System (INIS)

    Mackerness, A.H.S.; Liu, L.; Thomas, B.; Thompson, W.F.; Jordan, B.R.; White, M.J.

    1998-01-01

    In the present work, UV-B-repressible and UV-B-inducible genes were identified in the pea, Pisum sativum L., by rapid amplification of 3′ cDNA ends through use of the polymerase chain reaction. Of the UV-B-repressible clones, psUVRub and psUVDeh represent genes encoding Rubisco activase and dehydrin, respectively. A third clone, psUVZinc, did not correspond closely in overall nucleotide sequence to any gene registered in GenBank; however, a short deduced peptide shared similarity with the photosystem-II reaction center X protein of the chlorophyll a+c-containing alga, Odontella sinensis. The UV-B-inducible clones, psUVGluc, psUVAux and psUVRib, were related to genes encoding β-1, 3-glucanase, auxin-repressed protein, and a 40S ribosomal protein, respectively. The modulation of these pea genes indicates how UV-B, through its actions as a physical stressor, affects several important physiological processes in plants. (author)

  5. STAY-GREEN and Chlorophyll Catabolic Enzymes Interact at Light-Harvesting Complex II for Chlorophyll Detoxification during Leaf Senescence in Arabidopsis[C][W

    Science.gov (United States)

    Sakuraba, Yasuhito; Schelbert, Silvia; Park, So-Yon; Han, Su-Hyun; Lee, Byoung-Doo; Andrès, Céline Besagni; Kessler, Felix; Hörtensteiner, Stefan; Paek, Nam-Chon

    2012-01-01

    During leaf senescence, plants degrade chlorophyll to colorless linear tetrapyrroles that are stored in the vacuole of senescing cells. The early steps of chlorophyll breakdown occur in plastids. To date, five chlorophyll catabolic enzymes (CCEs), NONYELLOW COLORING1 (NYC1), NYC1-LIKE, pheophytinase, pheophorbide a oxygenase (PAO), and red chlorophyll catabolite reductase, have been identified; these enzymes catalyze the stepwise degradation of chlorophyll to a fluorescent intermediate, pFCC, which is then exported from the plastid. In addition, STAY-GREEN (SGR), Mendel’s green cotyledon gene encoding a chloroplast protein, is required for the initiation of chlorophyll breakdown in plastids. Senescence-induced SGR binds to light-harvesting complex II (LHCII), but its exact role remains elusive. Here, we show that all five CCEs also specifically interact with LHCII. In addition, SGR and CCEs interact directly or indirectly with each other at LHCII, and SGR is essential for recruiting CCEs in senescing chloroplasts. PAO, which had been attributed to the inner envelope, is found to localize in the thylakoid membrane. These data indicate a predominant role for the SGR-CCE-LHCII protein interaction in the breakdown of LHCII-located chlorophyll, likely to allow metabolic channeling of phototoxic chlorophyll breakdown intermediates upstream of nontoxic pFCC. PMID:22366162

  6. Identifying the public's concerns and the Centers for Disease Control and Prevention's reactions during a health crisis: An analysis of a Zika live Twitter chat.

    Science.gov (United States)

    Glowacki, Elizabeth M; Lazard, Allison J; Wilcox, Gary B; Mackert, Michael; Bernhardt, Jay M

    2016-12-01

    The arrival of the Zika virus in the United States caused much concern among the public because of its ease of transmission and serious consequences for pregnant women and their newborns. We conducted a text analysis to examine original tweets from the public and responses from the Centers for Disease Control and Prevention (CDC) during a live Twitter chat hosted by the CDC. Both the public and the CDC expressed concern about the spread of Zika virus, but the public showed more concern about the consequences it had for women and babies, whereas the CDC focused more on symptoms and education. Copyright © 2016 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.

  7. Retrospective analysis of non-laboratory-based adverse drug reactions induced by intravenous radiocontrast agents in a Joint Commission International-accredited academic medical center hospital in China

    Directory of Open Access Journals (Sweden)

    Chen QL

    2017-04-01

    Full Text Available Qin-lan Chen,1 Xiao-ying Zhao,2 Xiao-mi Wang,1 Na Lv,2 Ling-ling Zhu,3 Hui-min Xu,4 Quan Zhou4 1Radiology Nursing Unit, Division of Nursing, 2Department of Quality Management, 3Geriatric VIP Care Ward, Division of Nursing, 4Department of Pharmacy, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, People’s Republic of China Abstract: The authors retrospectively analyzed the pattern and characteristics of non-laboratory-based adverse drug reactions (ADRs induced by intravenous radiocontrast agents in a large-scale hospital in China during 2014–2015. There were 314 ADR cases among 118,208 patients receiving enhanced CT or MRI examinations. The frequency of moderate/severe ADRs defined by Chinese Society of Radiology (ie, severe vomiting, systematic urticaria, facial swelling, dyspnea, vasovagal reaction, laryngeal edema, seizure, trembling, convulsions, unconsciousness, shock, death, and other unexpected adverse reactions was rare (0.0431%, whereas the mild ADRs were uncommon (0.2225% and accounted for 83.76% of ADRs. Frequency of ADRs induced by iodinated contrast agents was related with examination site, sex, and type of patient settings (P<0.01 and was higher compared with gadolinium contrast agents (0.3676% vs 0.0504%, P<0.01. From 2014 to 2015, frequencies of total and moderate/severe ADRs induced by iodinated contrast agents decreased significantly (0.4410% vs 0.2947%, P<0.01; 0.0960% vs 0.0282%, P<0.01, respectively. Frequency of ADRs differed among different iodinated contrast and gadolinium contrast (P<0.05 agents. Iopromide’s ADR frequency in 2014 was significantly higher compared with iopamidol, ioversol, or iohexol (P<0.01. Frequency of moderate/severe ADRs induced by iodixanol was 4.1–5.4 times that of iohexol, iopromide, or iopamidol. Rash was the predominant ADR subtype (84.39% and occurred more frequently with iodixanol compared with iohexol, iopamidol, or ioversol (P<0

  8. [Estimation of forest canopy chlorophyll content based on PROSPECT and SAIL models].

    Science.gov (United States)

    Yang, Xi-guang; Fan, Wen-yi; Yu, Ying

    2010-11-01

    The forest canopy chlorophyll content directly reflects the health and stress of forest. The accurate estimation of the forest canopy chlorophyll content is a significant foundation for researching forest ecosystem cycle models. In the present paper, the inversion of the forest canopy chlorophyll content was based on PROSPECT and SAIL models from the physical mechanism angle. First, leaf spectrum and canopy spectrum were simulated by PROSPECT and SAIL models respectively. And leaf chlorophyll content look-up-table was established for leaf chlorophyll content retrieval. Then leaf chlorophyll content was converted into canopy chlorophyll content by Leaf Area Index (LAD). Finally, canopy chlorophyll content was estimated from Hyperion image. The results indicated that the main effect bands of chlorophyll content were 400-900 nm, the simulation of leaf and canopy spectrum by PROSPECT and SAIL models fit better with the measured spectrum with 7.06% and 16.49% relative error respectively, the RMSE of LAI inversion was 0. 542 6 and the forest canopy chlorophyll content was estimated better by PROSPECT and SAIL models with precision = 77.02%.

  9. Reaction dynamics of the four-centered elimination CH2OH + --> CHO + +H2: Measurement of kinetic energy release distribution and classical trajectory calculation

    Science.gov (United States)

    Lee, Tae Geol; Park, Seung C.; Kim, Myung Soo

    1996-03-01

    Mass-analyzed ion kinetic energy (MIKE) spectrum of CHO+ generated in the unimolecular dissociation of CH2OH+ was measured. Kinetic energy release distribution (KERD) was evaluated by analyzing the spectrum according to the algorithm developed previously. The average kinetic energy release evaluated from the distribution was extraordinarily large, 1.63 eV, corresponding to 75% of the reverse barrier of the reaction. A global analytical potential energy surface was constructed such that the experimental energetics was represented and that various features in the ab initio potential energy surface were closely reproduced. Classical trajectory calculation was carried out with the global analytical potential energy surface to investigate the causes for the extraordinarily large kinetic energy release. Based on the detailed dynamical calculations, it was found that the strained bending forces at the transition state and strengthening of the CO bond from double to triple bond character were mainly responsible for such a significant kinetic energy release. In addition, the dissociation products H2 and CHO+ ion were found to be rotationally excited in the trajectory calculations. This was attributed to the asymmetry of the transition state and the release of asymmetric bending forces. Also, the bending vibrational modes of CHO+ and the H2 stretching mode, which are coupled with the bending coordinates, were found to be moderately excited.

  10. Reaction-Based Reactive Transport Modeling of Iron Reduction and Uranium Immobilization at Area 2 of the NABIR Field Research Center

    Energy Technology Data Exchange (ETDEWEB)

    Burgos, W.D.

    2009-09-02

    This report summarizes research conducted in conjunction with a project entitled “Reaction-Based Reactive Transport Modeling of Iron Reduction and Uranium Immobilization at Area 2 of the NABIR Field Research Center”, which was funded through the Integrative Studies Element of the former NABIR Program (now the Environmental Remediation Sciences Program) within the Office of Biological and Environmental Research. Dr. William Burgos (The Pennsylvania State University) was the overall PI/PD for the project, which included Brian Dempsey (Penn State), Gour-Tsyh (George) Yeh (Central Florida University), and Eric Roden (formerly at The University of Alabama, now at the University of Wisconsin) as separately-funded co-PIs. The project focused on development of a mechanistic understanding and quantitative models of coupled Fe(III)/U(VI) reduction in FRC Area 2 sediments. The work builds on our previous studies of microbial Fe(III) and U(VI) reduction, and was directly aligned with the Scheibe et al. ORNL FRC Field Project at Area 2.

  11. Structural studies on reaction centers from thermophilic photosynthetic bacteria and its functional utilizations. Tainetsusei kogosei saikin ni yuraisuru kogosei hanno chushin no kozo kaimei to kino kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Nozawa, T; Morishita, Y; Kobayashi, M; Kanno, S [Tohoku University, Sendai (Japan). Faculty of Engineering

    1992-10-31

    This paper describes the results of the experiment in which crystallization of protein of reactive center purified from the photosynthetic film of thermophilic purple sulfur photosynthetic bacterium Chromatium tepidum whose hyrogen donor in photosynthesis is H2S instead of H2O was attempted. Crystallization was carried out by the vapor diffusion method and particularly by using ethylene glycol as precipitator at 4[degree]C after various investigations on the conditions of crystallization. By X-ray diffraction, this crystal was found to belong to the rhombic system, and it was estimated that the lattice constants, a, b, c equal to 140[angstrom], 190[angstrom] and 80[angstrom] respectively. This bacterium is a thermophilic bacterium having the optimum growth temperature of 48-50 [degree]C and utilizes CO2 or H2CO3 as corbon source, ammonium, urea etc. as nitrogen source and thiosulfate as sulfur source. Moreover, another purpose of this investigation was to determine the thermophilic location by elucidating its configuration (although, as a result, the analysis of configuration had no sufficient resolution). It was confirmed that the enzyme system of photosynthetic film and its cytoplasm obtained by ultrasonic spallation of this cell have CO2 fixing activity utilizing light energy. 23 refs., 14 figs., 3 tabs.

  12. Strong Impact of an Axial Ligand on the Absorption by Chlorophyll a and b Pigments Determined by Gas-Phase Ion Spectroscopy Experiments

    DEFF Research Database (Denmark)

    Kjaer, Christina; Stockett, Mark H.; Pedersen, Bjarke Møller

    2016-01-01

    The microenvironments in photosynthetic proteins affect the absorption by chlorophyll (Chl) pigments. It is, however, a challenge to disentangle the impact on the transition energies of different perturbations, for example, the global electrostatics of the protein (nonbonded environmental effects......), exciton coupling between Chl's, conformational variations, and binding of an axial ligand to the magnesium center. This is needed to distinguish between the two most commonly proposed mechanisms for energy transport in photosynthetic proteins, relying on either weakly or strongly coupled pigments. Here...

  13. Concurrent validity and reliability of using ground reaction force and center of pressure parameters in the determination of leg movement initiation during single leg lift.

    Science.gov (United States)

    Aldabe, Daniela; de Castro, Marcelo Peduzzi; Milosavljevic, Stephan; Bussey, Melanie Dawn

    2016-09-01

    Postural adjustment evaluations during single leg lift requires the initiation of heel lift (T1) identification. T1 measured by means of motion analyses system is the most reliable approach. However, this method involves considerable workspace, expensive cameras, and time processing data and setting up laboratory. The use of ground reaction forces (GRF) and centre of pressure (COP) data is an alternative method as its data processing and setting up is less time consuming. Further, kinetic data is normally collected using frequency samples higher than 1000Hz whereas kinematic data are commonly captured using 50-200Hz. This study describes the concurrent-validity and reliability of GRF and COP measurements in determining T1, using a motion analysis system as reference standard. Kinematic and kinetic data during single leg lift were collected from ten participants. GRF and COP data were collected using one and two force plates. Displacement of a single heel marker was captured by means of ten Vicon(©) cameras. Kinetic and kinematic data were collected using a sample frequency of 1000Hz. Data were analysed in two stages: identification of key events in the kinetic data, and assessing concurrent validity of T1 based on the chosen key events with T1 provided by the kinematic data. The key event presenting the least systematic bias, along with a narrow 95% CI and limits of agreement against the reference standard T1, was the Baseline COPy event. Baseline COPy event was obtained using one force plate and presented excellent between-tester reliability. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. Room temperature oxidation of the peripheral chlorophyll of photosystem II reaction centre

    Czech Academy of Sciences Publication Activity Database

    Litvín, R.; Vácha, František

    2004-01-01

    Roč. 26, - (2004), s. 98 ISSN 0137-5881. [FESPB Congress Book of Abstracts /14./. Cracow, 23.08.2004-27.08.2004] Keywords : plant physiology Subject RIV: CE - Biochemistry Impact factor: 0.433, year: 2004

  15. Room temperature photooxidation of beta-carotene and peripheral chlorophyll in photosystem II reaction centre

    Czech Academy of Sciences Publication Activity Database

    Litvín, Radek; Bína, David; Vácha, František

    2008-01-01

    Roč. 98, č. 2 (2008), s. 179-187 ISSN 0166-8595 R&D Projects: GA AV ČR IAA608170604 Institutional research plan: CEZ:AV0Z50510513 Keywords : photosystem II Subject RIV: BO - Biophysics Impact factor: 2.681, year: 2008

  16. Retrospective analysis of multiplex polymerase chain reaction-based molecular diagnostics (SES in 70 patients with suspected central nervous system infections: A single-center study

    Directory of Open Access Journals (Sweden)

    Rama Krishnan Tiruppur Chinnappan Ramalingam

    2016-01-01

    Full Text Available Background: Central nervous system (CNS infections present a grave health care challenge due to high morbidity and mortality. Clinical findings and conventional laboratory assessments are not sufficiently distinct for specific etiologic diagnosis. Identification of pathogens is a key to appropriate therapy. Aim: In this retrospective observational study, we evaluated the efficacy and clinical utility of syndrome evaluation system (SES for diagnosing clinically suspected CNS infections. Materials and Methods: This retrospective analysis included inpatients in our tertiary level neurointensive care unit (NICU and ward from February 2010 to December 2013. Cerebrospinal fluid (CSF samples of 70 patients, clinically suspected of having CNS infections, were subjected to routine laboratory tests, culture, imaging, and SES. We analyzed the efficacy of SES in the diagnosis of CNS infections and its utility in therapeutic decision-making. Results: SES had a clinical sensitivity of 57.4% and clinical specificity of 95.6%. Streptococcus pneumoniae and Pseudomonas aeruginosa were the top two bacterial pathogens, whereas Herpes simplex virus (HSV was the most common viral pathogen. Polymicrobial infections were detected in 32.14% of SES-positive cases. SES elicited a change in the management in 30% of the patients from initial empiric therapy. At discharge, 51 patients recovered fully while 11 patients had partial recovery. Three-month follow-up showed only six patients to have neurological deficits. Conclusion: In a tertiary care center, etiological microbial diagnosis is central to appropriate therapy and outcomes. Sensitive and accurate multiplex molecular diagnostics play a critical role in not only identifying the causative pathogen but also in helping clinicians to institute appropriate therapy, reduce overuse of antimicrobials, and ensure superior clinical outcomes.

  17. Retrospective analysis of multiplex polymerase chain reaction-based molecular diagnostics (SES) in 70 patients with suspected central nervous system infections: A single-center study.

    Science.gov (United States)

    Ramalingam, Rama Krishnan Tiruppur Chinnappan; Chakraborty, Dipanjan

    2016-01-01

    Central nervous system (CNS) infections present a grave health care challenge due to high morbidity and mortality. Clinical findings and conventional laboratory assessments are not sufficiently distinct for specific etiologic diagnosis. Identification of pathogens is a key to appropriate therapy. In this retrospective observational study, we evaluated the efficacy and clinical utility of syndrome evaluation system (SES) for diagnosing clinically suspected CNS infections. This retrospective analysis included inpatients in our tertiary level neurointensive care unit (NICU) and ward from February 2010 to December 2013. Cerebrospinal fluid (CSF) samples of 70 patients, clinically suspected of having CNS infections, were subjected to routine laboratory tests, culture, imaging, and SES. We analyzed the efficacy of SES in the diagnosis of CNS infections and its utility in therapeutic decision-making. SES had a clinical sensitivity of 57.4% and clinical specificity of 95.6%. Streptococcus pneumoniae and Pseudomonas aeruginosa were the top two bacterial pathogens, whereas Herpes simplex virus (HSV) was the most common viral pathogen. Polymicrobial infections were detected in 32.14% of SES-positive cases. SES elicited a change in the management in 30% of the patients from initial empiric therapy. At discharge, 51 patients recovered fully while 11 patients had partial recovery. Three-month follow-up showed only six patients to have neurological deficits. In a tertiary care center, etiological microbial diagnosis is central to appropriate therapy and outcomes. Sensitive and accurate multiplex molecular diagnostics play a critical role in not only identifying the causative pathogen but also in helping clinicians to institute appropriate therapy, reduce overuse of antimicrobials, and ensure superior clinical outcomes.

  18. Oceanic turbidity and chlorophyll as inferred from ERTS-1 observations

    Science.gov (United States)

    Curran, R. J.

    1973-01-01

    Spectral signatures of phytoplankton and other obscuring effects are considered in order to determine how to best use satellite data. The results of this study were then used to analyze the spectral data obtained from the ERTS-1 multispectral scanner (MSS). The analyzed satellite data were finally compared with surface ship measurements of chlorophyll concentration. It was found that the effects of water turbidity on the multispectral imagery can be discriminated by rationing the two shortest wavelength channels so that the effect of phytoplankton is enhanced.

  19. Influence of water-based ferrofluid upon chlorophylls in cereals

    Energy Technology Data Exchange (ETDEWEB)

    Racuciu, Mihaela [Lucian Blaga University, Faculty of Science, 10 Blvd. Victoriei, Sibiu, 550012 (Romania)]. E-mail: mracuciu@yahoo.com; Creanga, Dorina-Emilia [Al. I. Cuza University, Faculty of Physics, 11A Blvd.Copou, Iasi, 700506 (Romania)

    2007-04-15

    The present experimental investigation was focused on the study of the simultaneous influence of the water-based ferrofluid and static magnetic field exposure on young cereal plants. Water-based ferrofluid, stabilized with citric acid was added daily in various concentrations, ranging between 10 and 250 {mu}L/L, in the culture medium of maize (Zea mays) plants in their early ontogenetic stages. The used static magnetic field was about 50 mT. In order to investigate the biochemical changes of chlorophylls and total carotenoids, spectrophotometric measurements were carried out, that revealed stimulatory effects of ferrofluid and magnetic exposure upon the studied plant species.

  20. Influence of water-based ferrofluid upon chlorophylls in cereals

    International Nuclear Information System (INIS)

    Racuciu, Mihaela; Creanga, Dorina-Emilia

    2007-01-01

    The present experimental investigation was focused on the study of the simultaneous influence of the water-based ferrofluid and static magnetic field exposure on young cereal plants. Water-based ferrofluid, stabilized with citric acid was added daily in various concentrations, ranging between 10 and 250 μL/L, in the culture medium of maize (Zea mays) plants in their early ontogenetic stages. The used static magnetic field was about 50 mT. In order to investigate the biochemical changes of chlorophylls and total carotenoids, spectrophotometric measurements were carried out, that revealed stimulatory effects of ferrofluid and magnetic exposure upon the studied plant species

  1. Simple heterogeneity parametrization for sea surface temperature and chlorophyll

    Science.gov (United States)

    Skákala, Jozef; Smyth, Timothy J.

    2016-06-01

    Using satellite maps this paper offers a complex analysis of chlorophyll & SST heterogeneity in the shelf seas around the southwest of the UK. The heterogeneity scaling follows a simple power law and is consequently parametrized by two parameters. It is shown that in most cases these two parameters vary only relatively little with time. The paper offers a detailed comparison of field heterogeneity between different regions. How much heterogeneity is in each region preserved in the annual median data is also determined. The paper explicitly demonstrates how one can use these results to calculate representative measurement area for in situ networks.

  2. Role of chlorophylls, amino acids and sugars in tea

    International Nuclear Information System (INIS)

    Dev Choudhury, M.N.

    1980-01-01

    Plucked tea shoots from clones of different varieties of tea were withered, rolled, fermented and fired by CTC and orthodox methods of manufacture. Quantitative changes in the levels of chlorophylls, amino acids and water soluble sugars during different stages of processing of tea and also changes in the contents of their degradation products were studied by feeding 14 C-labelled phenylalanine, glucose, sodium carbonate and sodium propionate to the excised shoots and subsequently analysing the products. Results are discussed and suggestions have been made about adjusting the conditions of manufacture so that the teas with desired chemical constituents are produced. (M.G.B.)

  3. A Saponification Method for Chlorophyll Removal from Microalgae Biomass as Oil Feedstock

    Directory of Open Access Journals (Sweden)

    Tao Li

    2016-09-01

    Full Text Available Microalgae oil is an optimal feedstock for nutraceutical, pharmaceutical and biodiesel production, but its high levels of chlorophyll limit its large-scale application. To date, few effective approaches have been developed to remove chlorophyll from microalgae oil. The main purpose of this study was to present a preprocessing method of algae oil feedstock (Scenedesmus to remove chlorophyll by saponification. The results showed that 96% of chlorophyll in biomass was removed. High quality orange transparent oil could be extracted from the chlorophyll reduced biomass. Specifically, the proportion of neutral lipids and saturation levels of fatty acids increased, and the pigments composition became carotenoids-based. The critical parameters of chlorophyll reduced biodiesel conformed to the standards of the USA, China and EU. Sodium copper chlorophyllin could be prepared from the bleaching effluent. The results presented herein offer a useful pathway to improve the quality of microalgae oil and reduce the cost of microalgae biodiesel.

  4. A Saponification Method for Chlorophyll Removal from Microalgae Biomass as Oil Feedstock

    Science.gov (United States)

    Li, Tao; Xu, Jin; Wu, Hualian; Wang, Guanghua; Dai, Shikun; Fan, Jiewei; He, Hui; Xiang, Wenzhou

    2016-01-01

    Microalgae oil is an optimal feedstock for nutraceutical, pharmaceutical and biodiesel production, but its high levels of chlorophyll limit its large-scale application. To date, few effective approaches have been developed to remove chlorophyll from microalgae oil. The main purpose of this study was to present a preprocessing method of algae oil feedstock (Scenedesmus) to remove chlorophyll by saponification. The results showed that 96% of chlorophyll in biomass was removed. High quality orange transparent oil could be extracted from the chlorophyll reduced biomass. Specifically, the proportion of neutral lipids and saturation levels of fatty acids increased, and the pigments composition became carotenoids-based. The critical parameters of chlorophyll reduced biodiesel conformed to the standards of the USA, China and EU. Sodium copper chlorophyllin could be prepared from the bleaching effluent. The results presented herein offer a useful pathway to improve the quality of microalgae oil and reduce the cost of microalgae biodiesel. PMID:27618070

  5. A Saponification Method for Chlorophyll Removal from Microalgae Biomass as Oil Feedstock.

    Science.gov (United States)

    Li, Tao; Xu, Jin; Wu, Hualian; Wang, Guanghua; Dai, Shikun; Fan, Jiewei; He, Hui; Xiang, Wenzhou

    2016-09-07

    Microalgae oil is an optimal feedstock for nutraceutical, pharmaceutical and biodiesel production, but its high levels of chlorophyll limit its large-scale application. To date, few effective approaches have been developed to remove chlorophyll from microalgae oil. The main purpose of this study was to present a preprocessing method of algae oil feedstock (Scenedesmus) to remove chlorophyll by saponification. The results showed that 96% of chlorophyll in biomass was removed. High quality orange transparent oil could be extracted from the chlorophyll reduced biomass. Specifically, the proportion of neutral lipids and saturation levels of fatty acids increased, and the pigments composition became carotenoids-based. The critical parameters of chlorophyll reduced biodiesel conformed to the standards of the USA, China and EU. Sodium copper chlorophyllin could be prepared from the bleaching effluent. The results presented herein offer a useful pathway to improve the quality of microalgae oil and reduce the cost of microalgae biodiesel.

  6. Time-resolved interaction investigations of carbocyanine dyes and chlorophyll a in solution

    International Nuclear Information System (INIS)

    Feller, K.H.; Fassler, D.

    1983-01-01

    Using a Nd:YAG laser/streak camera system of 30 ps time resolution the quenching of the fluorescence of the carbocyanine dye ICC by chlorophyll a in methanolic solution was investigated. The fluorescence lifetime of ICC decreased within the chlorophyll concentration range 0 - 9x10 - 5 mol/l from 170 ps to 135 ps. The observed very effective fluorescence quenching process suggests that the formation of heteroaggregates from ICC and chlorophyll is responsible for the rapid energy transfer. (author)

  7. Chlorophyll metabolism in pollinated vs. parthenocarpic fig fruits throughout development and ripening.

    Science.gov (United States)

    Rosianskey, Yogev; Dahan, Yardena; Yadav, Sharawan; Freiman, Zohar E; Milo-Cochavi, Shira; Kerem, Zohar; Eyal, Yoram; Flaishman, Moshe A

    2016-08-01

    Expression of 13 genes encoding chlorophyll biosynthesis and degradation was evaluated. Chlorophyll degradation was differentially regulated in pollinated and parthenocarpic fig fruits, leading to earlier chlorophyll degradation in parthenocarpic fruits. Varieties of the common fig typically yield a commercial summer crop that requires no pollination, although it can be pollinated. Fig fruit pollination results in larger fruit size, greener skin and darker interior inflorescence color, and slows the ripening process compared to non-pollinated fruits. We evaluated the effect of pollination on chlorophyll content and levels of transcripts encoding enzymes of the chlorophyll metabolism in fruits of the common fig 'Brown Turkey'. We cloned and evaluated the expression of 13 different genes. All 13 genes showed high expression in the fruit skin, inflorescences and leaves, but extremely low expression in roots. Pollination delayed chlorophyll breakdown in the ripening fruit skin and inflorescences. This was correlated with the expression of genes encoding enzymes in the chlorophyll biosynthesis and degradation pathways. Expression of pheophorbide a oxygenase (PAO) was strongly negatively correlated with chlorophyll levels during ripening in pollinated fruits; along with its high expression levels in yellow leaves, this supports a pivotal role for PAO in chlorophyll degradation in figs. Normalizing expression levels of all chlorophyll metabolism genes in the pollinated and parthenocarpic fruit skin and inflorescences showed three synthesis (FcGluTR1, FcGluTR2 and FcCLS1) and three degradation (FcCLH1, FcCLH2 and FcRCCR1) genes with different temporal expression in the pollinated vs. parthenocarpic fruit skin and inflorescences. FcCAO also showed different expressions in the parthenocarpic fruit skin. Thus, chlorophyll degradation is differentially regulated in the pollinated and parthenocarpic fruit skin and inflorescences, leading to earlier and more sustained

  8. PIXE analysis of proteins from a photochemical center

    Science.gov (United States)

    Solís, C.; Oliver, A.; Andrade, E.

    1998-03-01

    In oxygen evolving photosynthetic organisms, light is absorbed and its energy used for the conversion of chemical products in two photosystems: PSI and PSII. Each photosystem is composed of a protein core which binds a pigment antenna and a Reaction Center (RC). RC of PSI is considered an "Iron-Sulfur" type. There are six components that participate in the charge separation after light absorption occurs in PSI: the center chlorophyll P700, two acceptors A 0 and A 1 and three FeS centers F X, F A and F B. However, the exact number of polypeptides, their exact molecular weight, their relative abundances and the active components associated to those polypeptides remain still to be completely characterized. In particular the FeS centers have been difficult to detect in a direct way in a gel band, because the amount of centers involved is under the detection limits of the conventional techniques. This study has been under-taken to explore the capability of particle induced X-ray emission (PIXE) to detect in a qualitative way the presence of Fe in some of the protein bands obtained by Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis (SDS-PAGE) from the PSI complex. The complex was isolated from membranes of thermophilic cyanobacteria: Synechochoccus sp. The polyacrylamide gel electrophoresis of the complex shows eight subunits of 66, 60-65, 14, 13, 9, 8 and 7 KDa. In-air PIXE was performed at 2 MeV and proved to be an adequate tool for direct identification of the iron present in the gel bands.

  9. Development of empirical potential functions for the study of molecular geometry, and applications to chlorophyll a dimers

    Energy Technology Data Exchange (ETDEWEB)

    Oie, Tetsuro [Univ. of Rochester, NY (United States); Univ. of Kansas, Lawrence, KS (United States). Dept. of Chemistry

    1980-07-28

    A purpose of the present studies is twofold: (1) development of an empirical potential function (EPF) and (2) application of it to the studies of photoreaction center chlorophyll a dimer. The reliable estimate of geometric structures and energies of large molecules by quantum mechanical methods is not possible at the present time. An alternative method is, therefore, needed for the studies of large molecular systems, and Chapter I is dedicated to the development of this tool, i.e., an empirical potential function, which could suffice this purpose. Because of a large number of variable chemical compositions and functional groups characteristically present in a large molecule, it is important to include a large number of structurally diverse molecules in the development of the EPF. In Chapter II, the EPF is applied to study the geometrical structure of a chlorophyll a (Chl a) dimer, which is believed to exist at the photoreaction center of green plants and is known to play an essential role in photosynthetic energy conversion. Although various models have been proposed for this dimer structure, there is still a great need for information concerning the detailed geometric structure of this dimer. Therefore, in this chapter the structural stabilities of various dimer models are examined by the EPF, and detailed and quantitative information on the structure and stability of these models is provided.

  10. Two-center three-electron bonding in ClNH{sub 3} revealed via helium droplet infrared laser Stark spectroscopy: Entrance channel complex along the Cl + NH{sub 3} → ClNH{sub 2} + H reaction

    Energy Technology Data Exchange (ETDEWEB)

    Moradi, Christopher P.; Douberly, Gary E., E-mail: douberly@uga.edu [Department of Chemistry, University of Georgia, Athens, Georgia 30602-2556 (United States); Xie, Changjian; Guo, Hua [Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131 (United States); Kaufmann, Matin [Department of Physical Chemistry II, Ruhr-University Bochum, D-44801 Bochum (Germany)

    2016-04-28

    Pyrolytic dissociation of Cl{sub 2} is employed to dope helium droplets with single Cl atoms. Sequential addition of NH{sub 3} to Cl-doped droplets leads to the formation of a complex residing in the entry valley to the substitution reaction Cl + NH{sub 3} → ClNH{sub 2} + H. Infrared Stark spectroscopy in the NH stretching region reveals symmetric and antisymmetric vibrations of a C{sub 3v} symmetric top. Frequency shifts from NH{sub 3} and dipole moment measurements are consistent with a ClNH{sub 3} complex containing a relatively strong two-center three-electron (2c–3e) bond. The nature of the 2c–3e bonding in ClNH{sub 3} is explored computationally and found to be consistent with the complexation-induced blue shifts observed experimentally. Computations of interconversion pathways reveal nearly barrierless routes to the formation of this complex, consistent with the absence in experimental spectra of two other complexes, NH{sub 3}Cl and Cl–HNH{sub 2}, which are predicted in the entry valley to the hydrogen abstraction reaction Cl + NH{sub 3} → HCl + NH{sub 2}.

  11. Rapid assessment of water pollution by airborne measurement of chlorophyll content.

    Science.gov (United States)

    Arvesen, J. C.; Weaver, E. C.; Millard, J. P.

    1971-01-01

    Present techniques of airborne chlorophyll measurement are discussed as an approach to water pollution assessment. The differential radiometer, the chlorophyll correlation radiometer, and an infrared radiometer for water temperature measurements are described as the key components of the equipment. Also covered are flight missions carried out to evaluate the capability of the chlorophyll correlation radiometer in measuring the chlorophyll content in water bodies with widely different levels of nutrients, such as fresh-water lakes of high and low eutrophic levels, marine waters of high and low productivity, and an estuary with a high sediment content. The feasibility and usefulness of these techniques are indicated.

  12. Effect of gamma radiation on chlorophylls contents, net photosynthesis and respiration of chlorella pyrenoidosa

    International Nuclear Information System (INIS)

    Fernandez Gonzalez, J.; Martin Moreno, C.

    1983-01-01

    The effect of five doses of gamma radiation: 10, 100, 500, 1000 and 5000 Gy on chlorophylls content, net photosynthesis and respiration of chlorella pyrenoidosa has been studied. A decrease in chlorophylls levels is produced after irradiation at 500, 1000 and 5000 Gy, being, at first 'b' chlorophyll affected to a greater extent than 'a' chlorophyll. Net photosynthesis and respiration decline throughout the time of the observations after irradiation, this depressing effect being much more remarkable for the first one. Net photosynthesis inhibition levels of about 30% have got only five hours post irradiation at a dose of 5000 Gy. (author)

  13. Chlorophyll bleaching by UV-irradiation in vitro and in situ: Absorption and fluorescence studies

    International Nuclear Information System (INIS)

    Zvezdanovic, Jelena; Cvetic, Tijana; Veljovic-Jovanovic, Sonja; Markovic, Dejan

    2009-01-01

    Chlorophyll bleaching by UV-irradiation has been studied by absorbance and fluorescence spectroscopy in extracts containing mixtures of photosynthetic pigments, in acetone and n-hexane solutions, and in aqueous thylakoid suspensions. Chlorophyll undergoes destruction (bleaching) accompanied by fluorescent transient formation obeying first-order kinetics. The bleaching is governed by UV-photon energy input, as well as by different chlorophyll molecular organizations in solvents of different polarities (in vitro), and in thylakoids (in situ). UV-C-induced bleaching of chlorophylls in thylakoids is probably caused by different mechanisms compared to UV-A- and UV-B-induced bleaching

  14. The effects of heavy metal ions on the chlorophyll content and cell membrane permeability of charophytes

    International Nuclear Information System (INIS)

    Fu Hualong; Chen Hao; Dong Bin; Qing Renwei

    2001-01-01

    The authors studied the effects of several heavy metal ions in different concentrations (Cd 2+ , Hg 2+ , Pb 2+ , Cr 6+ ) on the chlorophyll content and cell membrane permeability of Chara vulgaris L. It was discovered that the effects of heavy metal ions on the chlorophyll content and cell membrane permeability of Chara vulgaris L. changed with their different concentration. The trend was that the chlorophyll content and cell membrane permeability were decreased with the increase of the heavy metal ions. The degree of chlorophyll content affected was Cr 6+ , Cd 2+ , Hg 2+ , Pb 2+ , and that of cell membrane permeability affected was Cd 2+ , Cr 6+ , Hg 2+ , Pb 2+

  15. Efficiency of portable chlorophyll meters in assessing the nutritional status of wheat plants

    Directory of Open Access Journals (Sweden)

    Alessana F. Schlichting

    2015-12-01

    Full Text Available ABSTRACT The objective of this study was to verify the efficiency of two portable chlorophyll meters (Minolta SPAD® 502 and Falker ClorofiLOG® 1030 in assessing the nutritional status of wheat plants, correlating the indices from the devices and the direct determination of chlorophyll content with the concentration of nitrogen (N in the plant. The experiment was conducted in a greenhouse, in pots with 5 dm3 of Oxisol, in a completely randomized design, with six N doses (0, 80, 160, 240, 320 and 400 mg dm-3 and five replicates. At 47 days after emergence, the readings of SPAD and Falker indices and the quantification of chlorophyll content and N concentration in wheat plants were performed, as well as analysis of variance and correlation test, both at 0.05 probability level. The chlorophyll meters Minolta SPAD® 502 and Falker ClorofiLOG® 1030 do not differ with respect to the indirect determination of chlorophyll in wheat plants. The Falker chlorophyll index was statistically equal to the chlorophyll content. Indirect chlorophyll indices and chlorophyll content showed a high correlation with the N concentration in the plant.

  16. Distribution of phytoplankton groups within the deep chlorophyll maximum

    KAUST Repository

    Latasa, Mikel

    2016-11-01

    The fine vertical distribution of phytoplankton groups within the deep chlorophyll maximum (DCM) was studied in the NE Atlantic during summer stratification. A simple but unconventional sampling strategy allowed examining the vertical structure with ca. 2 m resolution. The distribution of Prochlorococcus, Synechococcus, chlorophytes, pelagophytes, small prymnesiophytes, coccolithophores, diatoms, and dinoflagellates was investigated with a combination of pigment-markers, flow cytometry and optical and FISH microscopy. All groups presented minimum abundances at the surface and a maximum in the DCM layer. The cell distribution was not vertically symmetrical around the DCM peak and cells tended to accumulate in the upper part of the DCM layer. The more symmetrical distribution of chlorophyll than cells around the DCM peak was due to the increase of pigment per cell with depth. We found a vertical alignment of phytoplankton groups within the DCM layer indicating preferences for different ecological niches in a layer with strong gradients of light and nutrients. Prochlorococcus occupied the shallowest and diatoms the deepest layers. Dinoflagellates, Synechococcus and small prymnesiophytes preferred shallow DCM layers, and coccolithophores, chlorophytes and pelagophytes showed a preference for deep layers. Cell size within groups changed with depth in a pattern related to their mean size: the cell volume of the smallest group increased the most with depth while the cell volume of the largest group decreased the most. The vertical alignment of phytoplankton groups confirms that the DCM is not a homogeneous entity and indicates groups’ preferences for different ecological niches within this layer.

  17. Allelic variations of a light harvesting chlorophyll a/b-binding protein gene (Lhcb1 associated with agronomic traits in barley.

    Directory of Open Access Journals (Sweden)

    Yanshi Xia

    Full Text Available Light-harvesting chlorophyll a/b-binding protein (LHCP is one of the most abundant chloroplast proteins in plants. Its main function is to collect and transfer light energy to photosynthetic reaction centers. However, the roles of different LHCPs in light-harvesting antenna systems remain obscure. Exploration of nucleotide variation in the genes encoding LHCP can facilitate a better understanding of the functions of LHCP. In this study, nucleotide variations in Lhcb1, a LHCP gene in barley, were investigated across 292 barley accessions collected from 35 different countries using EcoTILLING technology, a variation of the Targeting Induced Local Lesions In Genomes (TILLING. A total of 23 nucleotide variations were detected including three insert/deletions (indels and 20 single nucleotide polymorphisms (SNPs. Among them, 17 SNPs were in the coding region with nine missense changes. Two SNPs with missense changes are predicted to be deleterious to protein function. Seventeen SNP formed 31 distinguishable haplotypes in the barley collection. The levels of nucleotide diversity in the Lhcb1 locus differed markedly with geographic origins and species of accessions. The accessions from Middle East Asia exhibited the highest nucleotide and haplotype diversity. H. spontaneum showed greater nucleotide diversity than H. vulgare. Five SNPs in Lhcb1 were significantly associated with at least one of the six agronomic traits evaluated, namely plant height, spike length, number of grains per spike, thousand grain weight, flag leaf area and leaf color, and these SNPs may be used as potential markers for improvement of these barley traits.

  18. Contribution of chlorophyll fluorescence to the apparent vegetation reflectance

    International Nuclear Information System (INIS)

    Campbell, P.K. Entcheva; Middleton, E.M.; Corp, L.A.; Kim, M.S.

    2008-01-01

    Current strategies for monitoring the physiologic status of terrestrial vegetation rely on remote sensing reflectance data, which provide estimates of vigor based primarily on chlorophyll content. Chlorophyll fluorescence (ChlF) measurements offer a non-destructive alternative and a more direct approach for diagnosis of vegetation stress before a significant reduction in chlorophyll content has occurred. Thus, technology based on ChlF may allow more accurate carbon sequestration estimates and earlier stress detection than is possible when using reflectance data alone. However, the observed apparent vegetation reflectance (Ra) in reality includes contributions from both the reflected and fluoresced radiation. The aim of this study is to determine the relative contributions of reflectance and ChlF fractions to Ra in the red to near-infrared region (650-800 nm) of the spectrum. The practical objectives of the study are to: 1) evaluate the relationship between ChlF and reflectance at the foliar level for corn, soybean and maple; and 2) for corn, determine if the relationship established for healthy vegetation changes under nitrogen (N) deficiency. To obtain generally applicable results, experimental measurements were conducted on unrelated crop and tree species (corn, soybean and maple) under controlled conditions and a gradient of inorganic N fertilization levels. Optical reflectance spectra and actively induced ChlF emissions were collected on the same foliar samples, in conjunction with measurements of photosynthetic function, pigment levels, and carbon (C) and N content. The spectral trends were examined for similarities. On average, 10-20% of Ra at 685 nm was actually due to ChlF. The spectral trends in steady state and maximum fluorescence varied significantly, with steady state fluorescence (especially red, 685 nm) showing higher ability for species and treatment separation. The relative contribution of ChlF to Ra varied significantly among species, with maple

  19. Presence of a chlorophyll d-like pigment in Chlorella extracts

    NARCIS (Netherlands)

    Michel-Wolwertz, M.R.; Sironval, C.; Goedheer, J.C.

    1965-01-01

    Three chlorophyll a isomers (a₁, a₂ and a₃) were separated by the chromatography of Chlorella extracts on paper 1. One of these, chlorophyll (a₃) showed additional absorption bands at 688 and 455 mμ in diethyl ether. Chromatographic analysis could not decide whether these bands were due to a₃ or

  20. LAI and chlorophyll estimation for a heterogeneous grassland using hyperspectral measurements

    NARCIS (Netherlands)

    Darvishzadeh, R.; Skidmore, A.K.; Schlerf, M.; Atzberger, C.; Corsi, F.; Cho, M.A.

    2008-01-01

    The study shows that leaf area index (LAI), leaf chlorophyll content (LCC) and canopy chlorophyll content (CCC) can be mapped in a heterogeneous Mediterranean grassland from canopy spectral reflectance measurements. Canopy spectral measurements were made in the field using a GER 3700

  1. Influence of sulphur dioxide on chlorophyll content and catalase activity in some chosen lichen species

    Energy Technology Data Exchange (ETDEWEB)

    Kuziel, S

    1974-01-01

    The influence of SO/sub 2/ on changes in catalase activity and in chlorophyll content were investigated under laboratory conditions in several lichen species and in maize. In all the plants examined the chlorophyll content and catalase activity decreased after treatment with SO/sub 2/ as compared with that in the control plants.

  2. Low light intensity and nitrogen starvation modulate the chlorophyll content of Scenedesmus dimorphus.

    Science.gov (United States)

    Ferreira, V S; Pinto, R F; Sant'Anna, C

    2016-03-01

    Chlorophyll is a photosynthetic pigment found in plants and algal organisms and is a bioproduct with human health benefits and a great potential for use in the food industry. The chlorophyll content in microalgae strains varies in response to environmental factors. In this work, we assessed the effect of nitrogen depletion and low light intensity on the chlorophyll content of the Scenedesmus dimorphus microalga. The growth of S. dimorphus under low light intensity led to a reduction in cell growth and volume as well as increased cellular chlorophyll content. Nitrogen starvation led to a reduction in cell growth and the chlorophyll content, changes in the yield and productivity of chlorophylls a and b. Transmission electron microscopy was used to investigate the ultrastructural changes in the S. dimorphus exposed to nitrogen and light deficiency. In contrast to nitrogen depletion, low light availability was an effective mean for increasing the total chlorophyll content of green microalga S. dimorphus. The findings acquired in this work are of great biotechnological importance to extend knowledge of choosing the right culture condition to stimulate the effectiveness of microalgae strains for chlorophyll production purposes. © 2015 The Society for Applied Microbiology.

  3. Genetic and Hormonal Regulation of Chlorophyll Degradation during Maturation of Seeds with Green Embryos.

    Science.gov (United States)

    Smolikova, Galina; Dolgikh, Elena; Vikhnina, Maria; Frolov, Andrej; Medvedev, Sergei

    2017-09-16

    The embryos of some angiosperms (usually referred to as chloroembryos) contain chlorophylls during the whole period of embryogenesis. Developing embryos have photochemically active chloroplasts and are able to produce assimilates, further converted in reserve biopolymers, whereas at the late steps of embryogenesis, seeds undergo dehydration, degradation of chlorophylls, transformation of chloroplast in storage plastids, and enter the dormancy period. However, in some seeds, the process of chlorophyll degradation remains incomplete. These residual chlorophylls compromise the quality of seed material in terms of viability, nutritional value, and shelf life, and represent a serious challenge for breeders and farmers. The mechanisms of chlorophyll degradation during seed maturation are still not completely understood, and only during the recent decades the main pathways and corresponding enzymes could be characterized. Among the identified players, the enzymes of pheophorbide a oxygenase pathway and the proteins encoded by STAY GREEN ( SGR ) genes are the principle ones. On the biochemical level, abscisic acid (ABA) is the main regulator of seed chlorophyll degradation, mediating activity of corresponding catabolic enzymes on the transcriptional level. In general, a deep insight in the mechanisms of chlorophyll degradation is required to develop the approaches for production of chlorophyll-free high quality seeds.

  4. Study of 660 nm laser-induced photoluminescence of chlorophyll-a and its applications

    International Nuclear Information System (INIS)

    Song, Y; Zhang, D X; Zhang, H J

    2007-01-01

    Based on the phenomenon of chlorophyll a photoluminescence, this paper introduces a new method to measure the chlorophyll a content, using 660nm laser diode as a new kind of light source to stimulate fluorescence as well as combining a fiber and spectrum technique. We analyze the characteristics of laser-induced fluorescence spectrum of chlorophyll a and then put forward the new method using two parameters, the relative fluorescence intensity and fluorescence intensity ratio F685/F735, to measure the chlorophyll a content in the water and green leaves respectively. The experimental results indicate that it is completely feasible to give a visual judgment for chlorophyll a content, according to the fluorescence emission spectrum of chlorophyll a. Subsequently, it is verified by three kinds of typical applications. All of these provide a new kind of light source to develop the chlorophyll a fluorometry and further give a technical foundation of on-spot monitoring the chlorophyll a content in the ocean or in green leaves

  5. Nondestructive and intuitive determination of circadian chlorophyll rhythms in soybean leaves using multispectral imaging

    Science.gov (United States)

    Pan, Wen-Juan; Wang, Xia; Deng, Yong-Ren; Li, Jia-Hang; Chen, Wei; Chiang, John Y.; Yang, Jian-Bo; Zheng, Lei

    2015-01-01

    The circadian clock, synchronized by daily cyclic environmental cues, regulates diverse aspects of plant growth and development and increases plant fitness. Even though much is known regarding the molecular mechanism of circadian clock, it remains challenging to quantify the temporal variation of major photosynthesis products as well as their metabolic output in higher plants in a real-time, nondestructive and intuitive manner. In order to reveal the spatial-temporal scenarios of photosynthesis and yield formation regulated by circadian clock, multispectral imaging technique has been employed for nondestructive determination of circadian chlorophyll rhythms in soybean leaves. By utilizing partial least square regression analysis, the determination coefficients R2, 0.9483 for chlorophyll a and 0.8906 for chlorophyll b, were reached, respectively. The predicted chlorophyll contents extracted from multispectral data showed an approximately 24-h rhythm which could be entrained by external light conditions, consistent with the chlorophyll contents measured by chemical analyses. Visualization of chlorophyll map in each pixel offers an effective way to analyse spatial-temporal distribution of chlorophyll. Our results revealed the potentiality of multispectral imaging as a feasible nondestructive universal assay for examining clock function and robustness, as well as monitoring chlorophyll a and b and other biochemical components in plants. PMID:26059057

  6. Using hyperspectral remote sensing data for retrieving canopy chlorophyll and nitrogen content

    NARCIS (Netherlands)

    Clevers, J.G.P.W.; Kooistra, L.

    2012-01-01

    Plant stress is often expressed as a reduction in amount of biomass or leaf area index (LAI). In addition, stress may affect the plant pigment system, influencing the photosynthetic capacity of plants. Chlorophyll content is the main driver for this primary production. The chlorophyll content is

  7. TOXICITY OF INDUSTRIAL EFFLUENT ON TOTAL CHLOROPHYLL CONTENT OF CERTAIN AQUATIC MACROPHYTES

    OpenAIRE

    Singh Priti; Vishen Ashish; Wadhwani R; Pandey Y.N

    2012-01-01

    To assess the toxicity of industrial effluents on certain macrophytes, the total chlorophyll content of free floating, submerged and emergent macrophytes were estimated in concentrations of industrial effluents at varying exposure duration. The result revealed reduction in total chlorophyll content of exposed macrophytes at higher concentrations of industrial effluents on prolonged duration.

  8. Substratum as a driver of variation in periphyton chlorophyll and productivity in lakes

    DEFF Research Database (Denmark)

    Vadeboncoeur, Y.; Kalff, J.; Christoffersen, Kirsten Seestern

    2006-01-01

    content of periphyton on hard substrata (rocks and wood) was positively related to water-column total P (TP), whereas chlorophyll content of algae on sediment (epipelon) and TP were not significantly related. Chlorophyll content was up to 100× higher on sediments than on hard substrata. Within regions...... of the littoral zones in nutrient and energy cycles in lakes....

  9. Thermocline Regulated Seasonal Evolution of Surface Chlorophyll in the Gulf of Aden

    KAUST Repository

    Yao, Fengchao; Hoteit, Ibrahim

    2015-01-01

    , the Sea-Viewing Wide Field-of-View Sensor (SeaWiFS) ocean color data reveal that the Gulf of Aden also exhibits a prominent summer chlorophyll bloom and sustains elevated chlorophyll concentrations throughout the fall, and is a biophysical province

  10. Genetic and Hormonal Regulation of Chlorophyll Degradation during Maturation of Seeds with Green Embryos

    Directory of Open Access Journals (Sweden)

    Galina Smolikova

    2017-09-01

    Full Text Available The embryos of some angiosperms (usually referred to as chloroembryos contain chlorophylls during the whole period of embryogenesis. Developing embryos have photochemically active chloroplasts and are able to produce assimilates, further converted in reserve biopolymers, whereas at the late steps of embryogenesis, seeds undergo dehydration, degradation of chlorophylls, transformation of chloroplast in storage plastids, and enter the dormancy period. However, in some seeds, the process of chlorophyll degradation remains incomplete. These residual chlorophylls compromise the quality of seed material in terms of viability, nutritional value, and shelf life, and represent a serious challenge for breeders and farmers. The mechanisms of chlorophyll degradation during seed maturation are still not completely understood, and only during the recent decades the main pathways and corresponding enzymes could be characterized. Among the identified players, the enzymes of pheophorbide a oxygenase pathway and the proteins encoded by STAY GREEN (SGR genes are the principle ones. On the biochemical level, abscisic acid (ABA is the main regulator of seed chlorophyll degradation, mediating activity of corresponding catabolic enzymes on the transcriptional level. In general, a deep insight in the mechanisms of chlorophyll degradation is required to develop the approaches for production of chlorophyll-free high quality seeds.

  11. The effect of shade on chlorophyll and anthocyanin content of upland red rice

    Science.gov (United States)

    Muhidin; Syam'un, E.; Kaimuddin; Musa, Y.; Sadimantara, G. R.; Usman; Leomo, S.; Rakian, T. C.

    2018-02-01

    Upland red rice (Oryza sativa) is a staple food and contains anthocyanin, which can act as antioxidants, plays an important role both for the plant itself and for human health. Levels of antioxidants in rice can be affected by the availability of light. The results showed that the difference of shade, cultivar, and interaction both significantly affect the content of chlorophyll a, chlorophyll b and total chlorophyll. The results also showed that shade could increase chlorophyll in all cultivars tested. The highest levels of chlorophyll a were present in the moderate shade level (n2), then decreased at the shelter level (n3) and increased again at high levels (n4). While on chlorophyll content b, it appears that shade increased chlorophyll b in all cultivars tested and this increase was linear to the increase of shade. The shade treatment may increase the anthocyanin content and the increase depending on the type of cultivar. Increased levels of anthocyanin highest due to shade occurred on Jangkobembe cultivar. The original level of anthocyanin on Jangkobembe cultivar averaged 0.096 mg g-1 increased to 2.487 mg g-1 or increased 26 fold. It is concluded that the shade had a significant effect on the chlorophyll and anthocyanin content.

  12. Chlorophyll meter for estimating nitrogen status of irrigated wheat

    International Nuclear Information System (INIS)

    Schepers, J.S.

    2000-01-01

    Chlorophyll-meter readings, generated from the leaves of irrigated wheat at particular growth stages, were normalized to the data obtained with locally recommended rates of fertilizer N, in Chile China, India and Mexico. Normalizing permitted comparisons of crop-N status across growth stages, locations, cultivars, and years. Relative yields and meter readings at growth-stage Z-50 are presented; they revealed similar trends for India, China, and Chile, however, for Mexico, the combination of soil, wheat cultivar, and climate resulted in much less response to N fertilization in the meter data. The implications are discussed. The SPAD meter proved to be a good tool to monitor and evaluate the N status of irrigated wheat. (author)

  13. Chlorophyll mediated photodynamic inactivation of blue laser on Streptococcus mutans

    Science.gov (United States)

    Astuti, Suryani Dyah; Zaidan, A.; Setiawati, Ernie Maduratna; Suhariningsih

    2016-03-01

    Photodynamic inactivation is an inactivation method in microbial pathogens that utilize light and photosensitizer. This study was conducted to investigate photodynamic inactivation effects of low intensity laser exposure with various dose energy on Streptococcus mutans bacteria. The photodynamic inactivation was achieved with the addition of chlorophyll as photosensitizers. To determine the survival percentage of Streptococcus mutans bacteria after laser exposure, the total plate count method was used. For this study, the wavelength of the laser is 405 nm and variables of energy doses are 1.44, 2.87, 4.31, 5.74, 7.18, and 8.61 in J/cm2. The results show that exposure to laser with energy dose of 7.18 J/cm2 has the best photodynamic inactivation with a decrease of 78% in Streptococcus

  14. Canopy Level Chlorophyll Fluorescence and the PRI in a Cornfield

    Science.gov (United States)

    Middleton, Elizabeth M.; Cheng, Yen-Ben; Corp, Lawrence A.; Campbell, Petya K. E.; Huemmrich, K. Fred; Zhang, Qingyuan; Kustas, William P.

    2012-01-01

    Two bio-indicators, the Photochemical Reflectance Index (PRI) and solar-induced red and far-red Chlorophyll Fluorescence (SIF), were derived from directional hyperspectral observations and studied in a cornfield on two contrasting days in the growing season. Both red and far-red SIF exhibited higher values on the day when the canopy in the early senescent stage, but only the far-red SIF showed sensitivity to viewing geometry. Consequently, the red/far-red SIF ratio varied greatly among azimuth positions while the largest values were obtained for the "hotspot" at both growth stages. This ratio was lower (approx.0.88 +/- 0.4) in early July than in August when the ratio approached equivalence (near approx.1). In concert, the PRI exhibited stronger responses to both zenith and azimuth angles and different values on the two growth stages. The potential of using these indices to monitor photosynthetic activities needs further investigation

  15. Chlorophyll a with a farnesyl tail in thermophilic cyanobacteria.

    Science.gov (United States)

    Wiwczar, Jessica M; LaFountain, Amy M; Wang, Jimin; Frank, Harry A; Brudvig, Gary W

    2017-11-01

    Photosystem II (PSII) of oxygenic photosynthetic organisms normally contains exclusively chlorophyll a (Chl a) as its major light-harvesting pigment. Chl a canonically consists of the chlorin headgroup with a 20-carbon, 4-isoprene unit, phytyl tail. We have examined the 1.9 Å crystal structure of PSII from thermophilic cyanobacteria reported by Shen and coworkers in 2012 (PDB accession of 3ARC/3WU2). A newly refined electron density map from this structure, presented here, reveals that some assignments of the cofactors may be different from those modeled in the 3ARC/3WU2 structure, including a specific Chl a that appears to have a truncated tail by one isoprene unit. We provide experimental evidence using high-performance liquid chromatography and mass spectrometry for a small population of Chl a esterified to a 15-carbon farnesyl tail in PSII of thermophilic cyanobacteria.

  16. Chlorophyll a fluorescence to phenotype wheat genotypes for heat tolerance

    DEFF Research Database (Denmark)

    Sharma, Dew Kumari; Andersen, Sven Bode; Ottosen, Carl-Otto

    In prospects of global climate change, heat stress is a rising constraint for the productivity of wheat (Triticum aestivum L.). It is a heat-susceptible crop beyond 17-23oC temperature throughout its phenological stages, flowering phase being the most sensitive stage. Chlorophyll a fluorescence...... parameter, maximum quantum yield efficiency of PSII (Fv/Fm) is used as a physiological marker for early stress detection in PSII in plants. We established a reproducible protocol to measure response of wheat genotypes to high temperature based on Fv/Fm. The heat treatment of 40°C in 300 µmol m-2s-1 PAR...... enabled the identification of contrasting wheat genotypes that can be used to study the genetic and physiological nature of heat stress tolerance to dissect quantitative traits into simpler and more heritable traits....

  17. Lettuce flavonoids screening and phenotyping by chlorophyll fluorescence excitation ratio.

    Science.gov (United States)

    Zivcak, Marek; Brückova, Klaudia; Sytar, Oksana; Brestic, Marian; Olsovska, Katarina; Allakhverdiev, Suleyman I

    2017-06-01

    Environmentally induced variation and the genotypic differences in flavonoid and phenolic content in lettuce can be reliably detected using the appropriate parameters derived from the records of rapid non-invasive fluorescence technique. The chlorophyll fluorescence excitation ratio method was designed as a rapid and non-invasive tool to estimate the content of UV-absorbing phenolic compounds in plants. Using this technique, we have assessed the dynamics of accumulation of flavonoids related to developmental changes and environmental effects. Moreover, we have tested appropriateness of the method to identify the genotypic differences and fluctuations in total phenolics and flavonoid content in lettuce. Six green and two red genotypes of lettuce (Lactuca sativa L.) grown in pots were exposed to two different environments for 50 days: direct sunlight (UV-exposed) and greenhouse conditions (low UV). The indices based on the measurements of chlorophyll fluorescence after red, green and UV excitation indicated increase of the content of UV-absorbing compounds and anthocyanins in the epidermis of lettuce leaves. In similar, the biochemical analyses performed at the end of the experiment confirmed significantly higher total phenolic and flavonoid content in lettuce plants exposed to direct sun compared to greenhouse conditions and in red compared to green genotypes. As the correlation between the standard fluorescence indices and the biochemical records was negatively influenced by the presence of red genotypes, we proposed the use of a new parameter named Modified Flavonoid Index (MFI) taking into an account both absorbance changes due to flavonol and anthocyanin content, for which the correlation with flavonoid and phenolic content was relatively good. Thus, our results confirmed that the fluorescence excitation ratio method is useful for identifying the major differences in phenolic and flavonoid content in lettuce plants and it can be used for high-throughput pre

  18. The power of pigments, calibrating chemoclines with chlorophylls and carotenoids.

    Science.gov (United States)

    Junium, C. K.; Uveges, B. T.

    2017-12-01

    Phototrophic organisms produce a diversity of pigments that serve a broad range of specific biochemical functions. Pigments are either directly associated with the photosynthetic apparatus, the most notable being chlorophyll a, or are accessory pigments such as the carotenoid lutein. Their functions can also be categorized into roles that are related to light harvesting (e.g. fucoxanthin) or for photoprotection (e.g. scytonemin). The abundances of these two classes of pigments from environmental samples can provide specific information about photointensity and how it relates to environmental changes. For example, a deepening of the chemo/nutricline can result in the increased production of light gathering relative to photoprotective pigments. Here we apply a relatively simple approach that utilizes the abundance of photosynthetic relative to photoprotective pigments to help constrain changes in the water column position of the chemocline. To test the efficacy of this approach we have utilized the sedimentary record of the anoxic Lake Kivu in the East African Rift. Recent Lake Kivu sediments are punctuated by a series of sapropels that may be associated with overturn of the lake, and release of carbon dioxide and sulfide during potential limnic eruptions. Carbon and nitrogen isotopes decrease significantly at the onset of sapropel deposition and suggest that 13C-depleted dissolved inorganic carbon was upwelled into surface waters and was accompanied by high concentrations of ammonium, that allowed for 15N-depletion during incomplete nitrogen utilization. The pigment record, specifically the ratio of the photoprotective carotenoids lutein and zeaxanthin to chlorophyll a increases significantly at the onset of sapropel deposition. This suggests that the chemocline shallowed, displacing phototrophic communities toward the surface of the lake where light intensities required production of photoprotective pigments. This approach can easily be applied to a wide variety of

  19. Researches Regarding the Influence of Cold Storage on the Chlorophyll Content in Lettuce

    Directory of Open Access Journals (Sweden)

    Iuliana Cretescu

    2014-05-01

    Full Text Available The aim of the present investigations was to determine the effect of the cold storage period on the content of chlorophylls in the leaves of lettuce and arugula (rucola. The research material consisted in two types of lettuce (Lactuca sativa L. var. capitata; Lactuca sativa L. var. crispa and arugula (Eruca sativa purchased from supermarkets in Timisoara. The quantitative determination of chlorophyll pigments in leaves (SPAD was made by chlorophyll meter (SPAD 502 Konica-Minolta. During the few days cold storage at a temperature of 4ºC, the content of chlorophyll in the leaf significantly decreased, compared with that in the control group. After 3 days of cold storage arugula and lettuce (Lactuca sativa var. capitata values of chlorophyll content differ statistically very significantly (p<0.001 from the values found in the control group which for lettuce (Lactuca sativa L. var. crispa differs statistically significant (p < 0.05.

  20. The effect of storage temperature of cucumber fruit on chlorophyll fluorescence

    Directory of Open Access Journals (Sweden)

    Ryszard Kosson

    2013-12-01

    Full Text Available The effect of three storage temperature levels: 12,5°C, 20°C, and 1,5°C on basic indexes of chlorophyll fluorescence of cucumber fruits was studied. The greenhouse grown cucumber fruits cv. Wiktor F1 were stored in perforated polyethylene bags or without packages. The minimum chlorophyll fluorescence (Fo, maximum chlorophyll fluorescence (Fm, variable chlorophyll fluorescence (Fv and relative variable fluorescence (Fv/Fm of the cucumber peel were measured. Relative variable fluorescence was decTeasing when cucumbers were stored at temperature lower or higher than optimum level. The chlorophyll fluorescence measurements can be helpful for determination of appropriate temperature parameters of cucumber storage.

  1. Thermocline Regulated Seasonal Evolution of Surface Chlorophyll in the Gulf of Aden

    KAUST Repository

    Hoteit, Ibrahim

    2015-04-01

    The Gulf of Aden, although subject to seasonally reversing monsoonal winds, has been previously reported as an oligotrophic basin during summer, with elevated chlorophyll concentrations only occurring during winter due to convective mixing. However, the Sea-Viewing Wide Field-of-View Sensor (SeaWiFS) ocean color data reveal that the Gulf of Aden also exhibits a prominent summer chlorophyll bloom and sustains elevated chlorophyll concentrations throughout the fall, and is a biophysical province distinct from the adjacent Arabian Sea. Climatological hydrographic data suggest that the thermocline, hence the nutricline, in the entire gulf is markedly shoaled by the southwest monsoon during summer and fall. Under this condition, cyclonic eddies in the gulf can effectively pump deep nutrients to the surface layer and lead to the chlorophyll bloom in late summer, and, after the transition to the northeast monsoon in fall, coastal upwelling driven by the northeasterly winds produces a pronounced increase in surface chlorophyll concentrations along the Somali coast.

  2. Stomata character and chlorophyll content of tomato in response to Zn application under drought condition

    Science.gov (United States)

    Sakya, A. T.; Sulistyaningsih, E.; Indradewa, D.; Purwanto, B. H.

    2018-03-01

    This experiment was performed in order to evaluate the effects of Zn application under drought condition on tomato, especially its chlorophyll content and stomata character. This experiment was arranged in factorial using randomized complete block design with three replications. The treatment consisted of the Zn application method, namely: soil and foliar, the Zn dosage, namely: 0, 40 and 60 mg ZnSO4 kg-1 soil and two cultivars of tomato, namely: ‘Tyrana’ F1 and ‘Permata’ F1. The stress condition was induced by watering every 12 days of 3 weeks after transplanting until harvesting. The results showed that the soil with a Zn application under drought conditions increased the aperture stomata, chlorophyll b and chlorophyll a/b ratio. The response of stomata character, chlorophyll a and total chlorophyll in both cultivars was similar.

  3. Hyperspectral imaging detection of decayed honey peaches based on their chlorophyll content.

    Science.gov (United States)

    Sun, Ye; Wang, Yihang; Xiao, Hui; Gu, Xinzhe; Pan, Leiqing; Tu, Kang

    2017-11-15

    Honey peach is a very common but highly perishable market fruit. When pathogens infect fruit, chlorophyll as one of the important components related to fruit quality, decreased significantly. Here, the feasibility of hyperspectral imaging to determine the chlorophyll content thus distinguishing diseased peaches was investigated. Three optimal wavelengths (617nm, 675nm, and 818nm) were selected according to chlorophyll content via successive projections algorithm. Partial least square regression models were established to determine chlorophyll content. Three band ratios were obtained using these optimal wavelengths, which improved spatial details, but also integrates the information of chemical composition from spectral characteristics. The band ratio values were suitable to classify the diseased peaches with 98.75% accuracy and clearly show the spatial distribution of diseased parts. This study provides a new perspective for the selection of optimal wavelengths of hyperspectral imaging via chlorophyll content, thus enabling the detection of fungal diseases in peaches. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Chlorophyll Extraction from Microalgae: A Review on the Process Engineering Aspects

    Directory of Open Access Journals (Sweden)

    Aris Hosikian

    2010-01-01

    Full Text Available Chlorophyll is an essential compound in many everyday products. It is used not only as an additive in pharmaceutical and cosmetic products but also as a natural food colouring agent. Additionally, it has antioxidant and antimutagenic properties. This review discusses the process engineering of chlorophyll extraction from microalgae. Different chlorophyll extraction methods and chlorophyll purification techniques are evaluated. Our preliminary analysis suggests supercritical fluid extraction to be superior to organic solvent extraction. When compared to spectroscopic technique, high performance liquid chromatography was shown to be more accurate and sensitive for chlorophyll analysis. Finally, through CO2 capture and wastewater treatment, microalgae cultivation process was shown to have strong potential for mitigation of environmental impacts.

  5. Estimation of the effect of radionuclide contamination on Vicia sativa L. induction of chlorophyll fluorescence parameters using "Floratest" optical biosensor

    Science.gov (United States)

    Ruban, Yu.; Illienko, V.; Nesterova, N.; Pareniuk, O.; Shavanova, K.

    2017-12-01

    The presented research was aimed to determine the parameters of chlorophyll fluorescence (IChH) curve induction for Vicia sativa L. that were grown on radionuclide contaminated soils by using "Floratest" fluorometer. Plants were inoculated with 5 species of bacteria that might potentially block radionuclide uptake (Agrobacterium radiobacter IMBB-7246, Azotobacter chroococcum UKMB-6082, A. chroococcum UKMB-6003, Bacillus megaterium UKMB-5724, Rhizobium leguminosarum bv. viceae) and grown in sod-podzolic, chernozem and peat-bog soils, contaminated with 137Cs (4000±340 Bq/kg). As a result of research, it was determined that the most stressful factors for vetch plants are combination of soil radionuclide and presence of Bacillus megaterium UKM B-5724, as the number of inactive chlorophyll increased. In addition, the vetch plants significantly increased fixed level of fluorescence (Fst) under the influence of radioactive contamination in presence of Bacillus megaterium UKM B-5724, indicating inhibition of photosynthetic reactions. Other bacteria showed radioprotective properties in almost all types of soil.

  6. Effects of Different Metals on Photosynthesis: Cadmium and Zinc Affect Chlorophyll Fluorescence in Durum Wheat

    Directory of Open Access Journals (Sweden)

    Momchil Paunov

    2018-03-01

    Full Text Available A comparative study of the effects of exposure to high Cd2+ (50 µM and excess Zn2+ (600 µM on photosynthetic performance of hydroponically-grown durum wheat seedlings was performed. At day 8, Cd and Zn were added to the nutrient solution. After 7-days exposure, the chosen concentrations of both metals resulted in similar relative growth rate (RGR inhibitions of about 50% and comparable retardations of the CO2 assimilation rates (about 30% in the second developed leaf of wheat seedlings. Analysis of chlorophyll a fluorescence indicated that both metals disturbed photosynthetic electron transport processes which led to a 4- to 5-fold suppression of the efficiency of energy transformation in Photosystem II. Non-specific toxic effects of Cd and Zn, which prevailed, were an inactivation of part of Photosystem II reaction centres and their transformation into excitation quenching forms as well as disturbed electron transport in the oxygen-evolving complex. The specificity of the Cd and Zn modes of action was mainly expressed in the intensity of the toxicity effects: despite the similar inhibitions of the CO2 assimilation rates, the wheat photochemistry showed much more sensitivity to Cd than to Zn exposure.

  7. The synthesis of chlorophyll-a biosynthetic precursors and methyl substituted iron porphyrins

    International Nuclear Information System (INIS)

    Matera, K.M.

    1988-01-01

    The biosynthetic intermediates were incubated in a plant system. The activity levels calculated show that magnesium 6-acrylate porphyrins and one of the magnesium 6-β-hydroxypropionate porphyrins are not intermediates. In addition, plant systems incubated with 18 O 2 were found to synthesize magnesium 2,4-divinyl pheoporphyrin-a 5 incorporated with 18 O at the 9-carbonyl oxygen. Mass spectroscopy confirmed the presence of the oxygen label, thus eliminating one of two hypothesized pathways to chlorophyll-a. An overall description is given of iron porphyrins and iron porphyrin containing proteins. The function of the propionic side chains of the heme prosthetic group during electron transport reactions will be investigated. The synthesis of a series of iron(III) hexamethyl porphyrins with increasingly longer substituents in the remaining two peripheral positions of the porphyrin is described. Models for NMR studies of iron chlorin containing enzymes are discussed. Iron(III) pyropheophorbide-a and methyl pyropheophorbide-a were synthesized in addition to 5-CD 3 , 10-CD 2 iron(III) pyropheophorbide-a and methyl pyropheophorbide-a. Together, these pyropheophorbides were used to assign NMR resonances and ultimately provide a model for other iron chlorins. The synthesis of nickel(II) anhydro-mesorhodoporphyrin from zinc(III) anhydromesorhodochlorin is described; this nickel porphyrin was used as a standard for ring current calculations of reduced nickel analogs of anhydromesorhodoporphyrin

  8. Variability in the correlation between Asian dust storms and chlorophyll a concentration from the North to Equatorial Pacific.

    Directory of Open Access Journals (Sweden)

    Sai-Chun Tan

    Full Text Available A long-term record of Asian dust storms showed seven high-occurrence-frequency centers in China. The intrusion of Asian dust into the downwind seas, including the China seas, the Sea of Japan, the subarctic North Pacific, the North Pacific subtropical gyre, and the western and eastern Equatorial Pacific, has been shown to add nutrients to ocean ecosystems and enhance their biological activities. To explore the relationship between the transported dust from various sources to the six seas and oceanic biological activities with different nutrient conditions, the correlation between monthly chlorophyll a concentration in each sea and monthly dust storm occurrence frequencies reaching the sea during 1997-2007 was examined in this study. No correlations were observed between dust and chlorophyll a concentration in the 50 m China seas and the North Pacific subtropical gyre, the correlation coefficients were in the range 0.32-0.57. The correlation coefficients for the western and eastern Equatorial Pacific were relatively low (<0.36. These correlation coefficients were further interpreted in terms of the geographical distributions of dust sources, the transport pathways, the dust deposition, the nutrient conditions of oceans, and the probability of dust storms reaching the seas.

  9. An improved ENSO simulation by representing chlorophyll-induced climate feedback in the NCAR Community Earth System Model.

    Science.gov (United States)

    Kang, Xianbiao; Zhang, Rong-Hua; Gao, Chuan; Zhu, Jieshun

    2017-12-07

    The El Niño-Southern oscillation (ENSO) simulated in the Community Earth System Model of the National Center for Atmospheric Research (NCAR CESM) is much stronger than in reality. Here, satellite data are used to derive a statistical relationship between interannual variations in oceanic chlorophyll (CHL) and sea surface temperature (SST), which is then incorporated into the CESM to represent oceanic chlorophyll -induced climate feedback in the tropical Pacific. Numerical runs with and without the feedback (referred to as feedback and non-feedback runs) are performed and compared with each other. The ENSO amplitude simulated in the feedback run is more accurate than that in the non-feedback run; quantitatively, the Niño3 SST index is reduced by 35% when the feedback is included. The underlying processes are analyzed and the results show that interannual CHL anomalies exert a systematic modulating effect on the solar radiation penetrating into the subsurface layers, which induces differential heating in the upper ocean that affects vertical mixing and thus SST. The statistical modeling approach proposed in this work offers an effective and economical way for improving climate simulations.

  10. Reaction-Based Reactive Transport Modeling of Iron Reduction and Uranium Immobilization at Area 2 of the NABIR Field Research Center, Subproject to Co-PI Eric E. Roden. Final Report

    International Nuclear Information System (INIS)

    Roden, Eric E.

    2011-01-01

    This report summarizes research conducted in conjunction with a project entitled 'Reaction-Based Reactive Transport Modeling of Iron Reduction and Uranium Immobilization at Area 2 of the NABIR Field Research Center', which was funded through the Integrative Studies Element of the former NABIR Program (now the Environmental Remediation Sciences Program) within the Office of Biological and Environmental Research. Dr. William Burgos (The Pennsylvania State University) was the overall PI/PD for the project, which included Brian Dempsey (Penn State), Gour-Tsyh (George) Yeh (Central Florida University), and Eric Roden (formerly at The University of Alabama, now at the University of Wisconsin) as separately-funded co-PIs. The project focused on development of a mechanistic understanding and quantitative models of coupled Fe(III)/U(VI) reduction in FRC Area 2 sediments. The work builds on our previous studies of microbial Fe(III) and U(VI) reduction, and was directly aligned with the Scheibe et al. ORNL FRC Field Project at Area 2.

  11. Impact differences in ground reaction force and center of mass between the first and second landing phases of a drop vertical jump and their implications for injury risk assessment.

    Science.gov (United States)

    Bates, Nathaniel A; Ford, Kevin R; Myer, Gregory D; Hewett, Timothy E

    2013-04-26

    The drop vertical jump (DVJ) task is commonly used to assess biomechanical performance measures that are associated with ACL injury risk in athletes. Previous investigations have solely assessed the first landing phase. We examined the first and second landings of a DVJ for differences in the magnitude of vertical ground reaction force (vGRF) and position of center of mass (CoM). A cohort of 239 adolescent female basketball athletes completed a series of DVJ tasks from an initial box height of 31 cm. Dual force platforms and a three dimensional motion capture system recorded force and positional data for each trial. There was no difference in peak vGRF between landings (p=0.445), but side-to-side differences increased from the first to second landing (p=0.007). Participants demonstrated a lower minimum CoM during stance in the first landing than the second landing (p<0.001). The results have important implications for the future assessment of ACL injury risk behaviors in adolescent female athletes. Greater side-to-side asymmetry in vGRF and higher CoM during impact indicate the second landing of a DVJ may exhibit greater perturbation and better represent in-game mechanics associated with ACL injury risk. Copyright © 2013 Elsevier Ltd. All rights reserved.

  12. A Statistical Algorithm for Estimating Chlorophyll Concentration in the New Caledonian Lagoon

    Directory of Open Access Journals (Sweden)

    Guillaume Wattelez

    2016-01-01

    Full Text Available Spatial and temporal dynamics of phytoplankton biomass and water turbidity can provide crucial information about the function, health and vulnerability of lagoon ecosystems (coral reefs, sea grasses, etc.. A statistical algorithm is proposed to estimate chlorophyll-a concentration ([chl-a] in optically complex waters of the New Caledonian lagoon from MODIS-derived “remote-sensing” reflectance (Rrs. The algorithm is developed via supervised learning on match-ups gathered from 2002 to 2010. The best performance is obtained by combining two models, selected according to the ratio of Rrs in spectral bands centered on 488 and 555 nm: a log-linear model for low [chl-a] (AFLC and a support vector machine (SVM model or a classic model (OC3 for high [chl-a]. The log-linear model is developed based on SVM regression analysis. This approach outperforms the classical OC3 approach, especially in shallow waters, with a root mean squared error 30% lower. The proposed algorithm enables more accurate assessments of [chl-a] and its variability in this typical oligo- to meso-trophic tropical lagoon, from shallow coastal waters and nearby reefs to deeper waters and in the open ocean.

  13. Detection of Chlorophyll and Leaf Area Index Dynamics from Sub-weekly Hyperspectral Imagery

    Science.gov (United States)

    Houborg, Rasmus; McCabe, Matthew F.; Angel, Yoseline; Middleton, Elizabeth M.

    2016-01-01

    Temporally rich hyperspectral time-series can provide unique time critical information on within-field variations in vegetation health and distribution needed by farmers to effectively optimize crop production. In this study, a dense time series of images were acquired from the Earth Observing-1 (EO-1) Hyperion sensor over an intensive farming area in the center of Saudi Arabia. After correction for atmospheric effects, optimal links between carefully selected explanatory hyperspectral vegetation indices and target vegetation characteristics were established using a machine learning approach. A dataset of in-situ measured leaf chlorophyll (Chll) and leaf area index (LAI), collected during five intensive field campaigns over a variety of crop types, were used to train the rule-based predictive models. The ability of the narrow-band hyperspectral reflectance information to robustly assess and discriminate dynamics in foliar biochemistry and biomass through empirical relationships were investigated. This also involved evaluations of the generalization and reproducibility of the predictions beyond the conditions of the training dataset. The very high temporal resolution of the satellite retrievals constituted a specifically intriguing feature that facilitated detection of total canopy Chl and LAI dynamics down to sub-weekly intervals. The study advocates the benefits associated with the availability of optimum spectral and temporal resolution spaceborne observations for agricultural management purposes.

  14. Detection of chlorophyll and leaf area index dynamics from sub-weekly hyperspectral imagery

    KAUST Repository

    Houborg, Rasmus

    2016-10-25

    Temporally rich hyperspectral time-series can provide unique time critical information on within-field variations in vegetation health and distribution needed by farmers to effectively optimize crop production. In this study, a dense timeseries of images were acquired from the Earth Observing-1 (EO-1) Hyperion sensor over an intensive farming area in the center of Saudi Arabia. After correction for atmospheric effects, optimal links between carefully selected explanatory hyperspectral vegetation indices and target vegetation characteristics were established using a machine learning approach. A dataset of in-situ measured leaf chlorophyll (Chll) and leaf area index (LAI), collected during five intensive field campaigns over a variety of crop types, were used to train the rule-based predictive models. The ability of the narrow-band hyperspectral reflectance information to robustly assess and discriminate dynamics in foliar biochemistry and biomass through empirical relationships were investigated. This also involved evaluations of the generalization and reproducibility of the predictions beyond the conditions of the training dataset. The very high temporal resolution of the satellite retrievals constituted a specifically intriguing feature that facilitated detection of total canopy Chl and LAI dynamics down to sub-weekly intervals. The study advocates the benefits associated with the availability of optimum spectral and temporal resolution spaceborne observations for agricultural management purposes.

  15. Detection of chlorophyll and leaf area index dynamics from sub-weekly hyperspectral imagery

    KAUST Repository

    Houborg, Rasmus; McCabe, Matthew; Angel, Yoseline; Middleton, Elizabeth M.

    2016-01-01

    Temporally rich hyperspectral time-series can provide unique time critical information on within-field variations in vegetation health and distribution needed by farmers to effectively optimize crop production. In this study, a dense timeseries of images were acquired from the Earth Observing-1 (EO-1) Hyperion sensor over an intensive farming area in the center of Saudi Arabia. After correction for atmospheric effects, optimal links between carefully selected explanatory hyperspectral vegetation indices and target vegetation characteristics were established using a machine learning approach. A dataset of in-situ measured leaf chlorophyll (Chll) and leaf area index (LAI), collected during five intensive field campaigns over a variety of crop types, were used to train the rule-based predictive models. The ability of the narrow-band hyperspectral reflectance information to robustly assess and discriminate dynamics in foliar biochemistry and biomass through empirical relationships were investigated. This also involved evaluations of the generalization and reproducibility of the predictions beyond the conditions of the training dataset. The very high temporal resolution of the satellite retrievals constituted a specifically intriguing feature that facilitated detection of total canopy Chl and LAI dynamics down to sub-weekly intervals. The study advocates the benefits associated with the availability of optimum spectral and temporal resolution spaceborne observations for agricultural management purposes.

  16. Chemical transformations of chlorophyll and its application in the design of a new generation of environmentally safe dyes

    Energy Technology Data Exchange (ETDEWEB)

    Berezin, Boris D; Rumyantseva, Svetlana V; Moryganov, Andrey P; Berezin, Mikhail B [Institute of Solution Chemistry, Russian Academy of Sciences, Ivanovo (Russian Federation)

    2004-02-28

    Chemical transformations of chlorophyll and physicochemical properties of its derivatives are considered. These compounds can be used in the design of a new generation of chlorophyll- and porphyrin-based dyes environmentally more safe than currently used arene dyes and possessing renewable sources of raw materials. The first results on the use of chlorophyll derivatives for dyeing wool, acetate fibres and cotton are reported.

  17. Chemical transformations of chlorophyll and its application in the design of a new generation of environmentally safe dyes

    International Nuclear Information System (INIS)

    Berezin, Boris D; Rumyantseva, Svetlana V; Moryganov, Andrey P; Berezin, Mikhail B

    2004-01-01

    Chemical transformations of chlorophyll and physicochemical properties of its derivatives are considered. These compounds can be used in the design of a new generation of chlorophyll- and porphyrin-based dyes environmentally more safe than currently used arene dyes and possessing renewable sources of raw materials. The first results on the use of chlorophyll derivatives for dyeing wool, acetate fibres and cotton are reported.

  18. Chlorophyll stability in yerba maté leaves in controlled atmospheres

    Directory of Open Access Journals (Sweden)

    Rubén O. Morawicki

    1999-01-01

    Full Text Available The objective of this research was to investigate the stability of chlorophyll in yerba maté leaves in controlled atmospheres of CO2/air mixtures and different water activities at 25°C.Two levels of water activity were selected corresponding to saturated salt solutions of LiCl (a w=0.113 and MgCl2(a w=0.330 and three levels of CO2/air mixtures (0/100,20/80 and 40/60. The chlorophyll content was evaluated using a liquid chromatography HPLC technique. Experimental values varied between 2.16 and 0.61 mg/g of dry matter. For each sample, 5 determination were made during 58 days. Experimental values were fitted to an equation describing a first order reaction. In all cases, the agreement was good with PO objetivo deste trabalho foi pesquisar a estabilidade da clorofila em folhas de erva mate em misturas atmosféricas controladas de CO2/ar e diferentes atividades de vapor de água a 25ºC. Dois níveis de atividade de vapor de água foram selecionadas, correspondendo a soluçoes saturadas de LiCl (a w=0.113 e MgCl2 (a w=0.330 e três níveis de misturas CO2/ar (0/100,20/80 e 40/60. O conteúdo de clorofila foi avaliado usando a técnica de cromatografia líqüida HPLC. Os valores experimentais variaram entre 2.16 e 0.61 mg/g de matéria seca. Para cada amostra foram realizadas 5 determinaçoes durante 58 dias. Os valores experimentais foram ajustados para uma eqüação descrevendo uma reação de primeiro ordem. Em todos os casos houve boa concordância P < 3 10-3. A concentração inicial de clorofila ficou reduzida em média um 30.5% depois de 58 dias. Porém, depois da comparação das constantes de velocidade, não foram achadas diferenças entre elas.

  19. Nuclear reactions

    International Nuclear Information System (INIS)

    Lane, A.M.

    1980-01-01

    In reviewing work at Harwell over the past 25 years on nuclear reactions it is stated that a balance has to be struck in both experiment and theory between work on cross-sections of direct practical relevance to reactors and on those relevant to an overall understanding of reaction processes. The compound nucleus and direct process reactions are described. Having listed the contributions from AERE, Harwell to developments in nuclear reaction research in the period, work on the optical model, neutron capture theory, reactions at doorway states with fine structure, and sum-rules for spectroscopic factors are considered in more detail. (UK)

  20. On the ultrafast kinetics of the energy and electron transfer reactions in photosystem I

    Energy Technology Data Exchange (ETDEWEB)

    Slavov, Chavdar Lyubomirov

    2009-07-09

    The subject of the current work is one of the main participants in the light-dependent phase of oxygenic photosynthesis, Photosystem I (PS I). This complex carries an immense number of cofactors: chlorophylls (Chl), carotenoids, quinones, etc, which together with the protein entity exhibit several exceptional properties. First, PS I has an ultrafast light energy trapping kinetics with a nearly 100% quantum efficiency. Secondly, both of the electron transfer branches in the reaction center are suggested to be active. Thirdly, there are some so called 'red' Chls in the antenna system of PS I, absorbing light with longer wavelengths than the reaction center. These 'red' Chls significantly modify the trapping kinetics of PS I. The purpose of this thesis is to obtain better understanding of the above-mentioned, specific features of PS I. This will not merely cast more light on the mechanisms of energy and electron transfer in the complex, but also will contribute to the future developments of optimized artificial light-harvesting systems. In the current work, a number of PS I complexes isolated from different organisms (Thermosynechococcus elongatus, Chlamydomonas reinhardtii, Arabidopsis thaliana) and possessing distinctive features (different macroorganisation, monomers, trimers, monomers with a semibelt of peripheral antenna attached; presence of 'red' Chls) is investigated. The studies are primarily focused on the electron transfer kinetics in each of the cofactor branches in the PS I reaction center, as well as on the effect of the antenna size and the presence of 'red' Chls on the trapping kinetics of PS I. These aspects are explored with the help of several ultrafast optical spectroscopy methods: (i) time-resolved fluorescence ? single photon counting and synchroscan streak camera; and (ii) ultrafast transient absorption. Physically meaningful information about the molecular mechanisms of the energy trapping in PS I is

  1. Near infrared fluorescent chlorophyll nanoscale liposomes for sentinel lymph node mapping

    Science.gov (United States)

    Fan, Lina; Wu, Qiang; Chu, Maoquan

    2012-01-01

    Background Sentinel lymph node (SLN) mapping using in vivo near infrared fluorescence imaging has attracted great attention during the past few years. Here we report on the early use of poorly water-soluble chlorophyll with near infrared fluorescence extracted from the leaf of Chimonanthus salicifolius, for mouse axillary SLN mapping. Methods and results To improve the water solubility and SLN targeting of the chlorophyll, we encapsulated the chlorophyll in nanoscale liposomes. The liposome-coated chlorophyll nanocomposites obtained were spherical in shape and had an average diameter of 21.7 ± 6.0 nm. The nanocomposites dispersed well in water, and in aqueous suspension they exhibited brighter near infrared fluorescence than chlorophyll alone. After incubation of the nanocomposites with normal liver cells (QSG-7701) and macrophage cells (Ana-1) for no more than 48 hours, there was no obvious reduction in cell viability. When the nanocomposites were injected intradermally into the paw of a mouse, the axillary SLN was found to be strongly fluorescent and was easily visualized in real time without a requirement for surgery. The intensity of the near infrared fluorescence emitted by the SLN was obviously brighter than that emitted by the SLN of another mouse that had been intradermally injected with chlorophyll alone. Conclusion Our data show that the liposome-coated chlorophyll nanocomposites could have great potential for clinical SLN mapping due to their lack of toxicity, bright near infrared fluorescence, and small diameter. PMID:22787402

  2. Completing the Feedback Loop: The Impact of Chlorophyll Data Assimilation on the Ocean State

    Science.gov (United States)

    Borovikov, Anna; Keppenne, Christian; Kovach, Robin

    2015-01-01

    In anticipation of the integration of a full biochemical model into the next generation GMAO coupled system, an intermediate solution has been implemented to estimate the penetration depth (1Kd_PAR) of ocean radiation based on the chlorophyll concentration. The chlorophyll is modeled as a tracer with sources-sinks coming from the assimilation of MODIS chlorophyll data. Two experiments were conducted with the coupled ocean-atmosphere model. In the first, climatological values of Kpar were used. In the second, retrieved daily chlorophyll concentrations were assimilated and Kd_PAR was derived according to Morel et al (2007). No other data was assimilated to isolate the effects of the time-evolving chlorophyll field. The daily MODIS Kd_PAR product was used to validate the skill of the penetration depth estimation and the MERRA-OCEAN re-analysis was used as a benchmark to study the sensitivity of the upper ocean heat content and vertical temperature distribution to the chlorophyll input. In the experiment with daily chlorophyll data assimilation, the penetration depth was estimated more accurately, especially in the tropics. As a result, the temperature bias of the model was reduced. A notably robust albeit small (2-5 percent) improvement was found across the equatorial Pacific ocean, which is a critical region for seasonal to inter-annual prediction.

  3. Efficiency of chlorophyll in gross primary productivity: A proof of concept and application in crops.

    Science.gov (United States)

    Gitelson, Anatoly A; Peng, Yi; Viña, Andrés; Arkebauer, Timothy; Schepers, James S

    2016-08-20

    One of the main factors affecting vegetation productivity is absorbed light, which is largely governed by chlorophyll. In this paper, we introduce the concept of chlorophyll efficiency, representing the amount of gross primary production per unit of canopy chlorophyll content (Chl) and incident PAR. We analyzed chlorophyll efficiency in two contrasting crops (soybean and maize). Given that they have different photosynthetic pathways (C3 vs. C4), leaf structures (dicot vs. monocot) and canopy architectures (a heliotrophic leaf angle distribution vs. a spherical leaf angle distribution), they cover a large spectrum of biophysical conditions. Our results show that chlorophyll efficiency in primary productivity is highly variable and responds to various physiological and phenological conditions, and water availability. Since Chl is accessible through non-destructive, remotely sensed techniques, the use of chlorophyll efficiency for modeling and monitoring plant optimization patterns is practical at different scales (e.g., leaf, canopy) and under widely-varying environmental conditions. Through this analysis, we directly related a functional characteristic, gross primary production with a structural characteristic, canopy chlorophyll content. Understanding the efficiency of the structural characteristic is of great interest as it allows explaining functional components of the plant system. Copyright © 2016 Elsevier GmbH. All rights reserved.

  4. Differential effects of glyphosate and aminomethylphosphonic acid (AMPA) on photosynthesis and chlorophyll metabolism in willow plants.

    Science.gov (United States)

    Gomes, Marcelo Pedrosa; Le Manac'h, Sarah Gingras; Maccario, Sophie; Labrecque, Michel; Lucotte, Marc; Juneau, Philippe

    2016-06-01

    We used a willow species (Salix miyabeana cultivar SX64) to examine the differential secondary-effects of glyphosate and aminomethylphosphonic acid (AMPA), the principal glyphosate by-product, on chlorophyll metabolism and photosynthesis. Willow plants were treated with different concentrations of glyphosate (equivalent to 0, 1.4, 2.1 and 2.8kgha(-1)) and AMPA (equivalent to 0, 0.28, 1.4 and 2.8kgha(-1)) and evaluations of pigment contents, chlorophyll fluorescence, and oxidative stress markers (hydrogen peroxide content and antioxidant enzyme activities) in leaves were performed after 12h of exposure. We observed that AMPA and glyphosate trigger different mechanisms leading to decreases in chlorophyll content and photosynthesis rates in willow plants. Both chemicals induced ROS accumulation in willow leaves although only glyphosate-induced oxidative damage through lipid peroxidation. By disturbing chlorophyll biosynthesis, AMPA induced decreases in chlorophyll contents, with consequent effects on photosynthesis. With glyphosate, ROS increases were higher than the ROS-sensitive threshold, provoking chlorophyll degradation (as seen by pheophytin accumulation) and invariable decreases in photosynthesis. Peroxide accumulation in both AMPA and glyphosate-treated plants was due to the inhibition of antioxidant enzyme activities. The different effects of glyphosate on chlorophyll contents and photosynthesis as described in the literature may be due to various glyphosate:AMPA ratios in those plants. Copyright © 2015 Elsevier Inc. All rights reserved.

  5. Correlation of electronic carotenoid-chlorophyll interactions and fluorescence quenching with the aggregation of native LHC II and chlorophyll deficient mutants

    International Nuclear Information System (INIS)

    Liao, Pen-Nan; Bode, Stefan; Wilk, Laura; Hafi, Nour; Walla, Peter J.

    2010-01-01

    The aggregation dependent correlation between fluorescence quenching and the electronic carotenoid-chlorophyll interactions, φ Coupling Car S 1 -Chl , as measured by comparing chlorophyll fluorescence observed after two- and one-photon excitation, has been investigated using native LHC II samples as well as mutants lacking Chl 2 and Chl 13. For native LHC II the same linear correlation between φ Coupling Car S 1 -Chl and the fluorescence quenching was observed as previously reported for the pH and Zea-dependent quenching of LHC II . In order to elucidate which carotenoid-chlorophyll pair might dominate this correlation we also investigated the mutants lacking Chl 2 and Chl 13. However, also with these mutants the same linear correlation as for native LHC II was observed. This provides indication that these two chlorophylls play only a minor role for the observed effects. Nevertheless, we also conclude that this does not exclude that their neighboured carotenoids, lutein 1 and neoxanthin, might interact electronically with other chlorophylls close by.

  6. Impact of petrochemicals on the photosynthesis of Halophila ovalis using chlorophyll fluorescence

    International Nuclear Information System (INIS)

    Ralph, P.J.; Burchett, M.D.

    1998-01-01

    Laboratory-cultured Halophila ovalis showed tolerance to petrochemical exposure up to 1% (w/v) solution of Bass Strait crude oil, an oil dispersant (Corexit 9527) and a mixture of crude oil and dispersant. Quantum yield, as measured by chlorophyll fluorescence, was the most sensitive measure of the photosynthetic processes affected by petrochemical. The results indicated clearly that chlorophyll fluorescence was effective at monitoring the onset and development of stress and recovery of H. ovalis when exposed to crude oil, dispersant and a mixture of the two compounds. Photosynthetic pigment content generally confirmed the chlorophyll fluorescence response; however, several anomalies occurred. (author)

  7. Magnetic field dependence of the current flowing in the spin-coated chlorophyll thin films

    Science.gov (United States)

    Aji, J. R. P.; Kusumandari; Purnama, B.

    2018-03-01

    The magnetic dependence of the current flowing in the spin coated chlorophyll films on a patterned Cu PCB substrate has been presented. Chlorophyll was isolated from Spirulina sp and deposited by spin coated methods. The reducing of current by the change of magnetic field (magneto conductance effect) was performed by inducing the magnetic field parallel to the inplane of film at room temp. The magnetoconductance ratio decreases as the increase of voltage. It was indicated that the origin of carrier charge in chlorophyll films should be different with the carrier charge injection (electron).

  8. Influence of frequent magnetic field on chlorophyll content in leaves of sugar beet plants

    International Nuclear Information System (INIS)

    Rochalska, M.

    2005-01-01

    Chlorophyll content in plant leaves is correlated with the yield and nitrogen content in plants. Non-destructive investigations of chlorophyll content in leaves of 3 varieties of sugar beet grown from seeds revealed that a low frequent magnetic field, acting independently or in combination with other methods of seed improvement, increased chlorophyll content in leaves of the investigated plants. The treatment with the magnetic field increased nitrogen content in the examined plants. The effect was not connected with environmental conditions during vegetation seasons. (author)

  9. Analysis of chlorophyll mutations induced by γ-rays in barley (hordeum vulgare)

    International Nuclear Information System (INIS)

    Wang Cailian; Shen Mei; Xu Gang; Zhao Kongnan; Chen Qiufang

    1991-06-01

    Thirty varieties of dormant barley seeds were irradiated with 137 Cs γ-rays. Dose-effect relations of chlorophyll mutation frequency in M 2 seedling and differences resulting from cultured types or radiosensitive types were investigated. Experimental results show that the relations between chlorophyll mutation frequency and doses can be fitted by a linear regression equation Y = A + BX. According to analysis of covariance, there is no considerable difference in various cultured types, but the difference of five different radiosensitive types is remarkable. The sensitive and intermediate types need much lower doses than other types to induce maximum chlorophyll mutation

  10. A micellar model system for the role of zeaxanthin in the non-photochemical quenching process of photosynthesis--chlorophyll fluorescence quenching by the xanthophylls.

    Science.gov (United States)

    Avital, Shlomo; Brumfeld, Vlad; Malkin, Shmuel

    2006-07-01

    To get an insight to the mechanism of the zeaxanthin-dependent non-photochemical quenching in photosystem II of photosynthesis, we probed the interaction of some xanthophylls with excited chlorophyll-a by trapping both pigments in micelles of triton X-100. Optimal distribution of pigments among micelles was obtained by proper control of the micelle concentration, using formamide in the reaction mixture, which varies the micellar aggregation number over three orders of magnitude. The optimal reaction mixture was obtained around 40% (v/v) formamide in 0.2-0.4% (v/v) triton X-100 in water. Zeaxanthin in the micellar solution exhibited initially absorption and circular dichroism spectral features corresponding to a J-type aggregate. The spectrum was transformed over time (half-time values vary-an average characteristic figure is roughly 20 min) to give features representing an H-type aggregate. The isosbestic point in the series of spectral curves favors the supposition of a rather simple reaction between two pure J and H-types dimeric species. Violaxanthin exhibited immediately stable spectral features corresponding to a mixture of J-type and more predominately H-type dimers. Lutein, neoxanthin and beta-carotene did not show any aggregated spectral forms in micelles. The spectral features in micelles were compared to spectra in aqueous acetone, where the assignment to various aggregated types was established previously. The specific tendency of zeaxanthin to form the J-type dimer (or aggregate) could be important for its function in photosynthesis. The abilities of five carotenoids (zeaxanthin, violaxanthin, lutein, neoxanthin and beta-carotene) to quench chlorophyll-a fluorescence were compared. Zeaxanthin, in its two micellar dimeric forms, and beta-carotene were comparable good quenchers of chlorophyll-a fluorescence. Violaxanthin was a much weaker quencher, if at all. Lutein and neoxanthin rather enhanced the fluorescence. The implications to non

  11. Leaf and canopy photosynthesis of a chlorophyll deficient soybean mutant.

    Science.gov (United States)

    Sakowska, Karolina; Alberti, Giorgio; Genesio, Lorenzo; Peressotti, Alessandro; Delle Vedove, Gemini; Gianelle, Damiano; Colombo, Roberto; Rodeghiero, Mirco; Panigada, Cinzia; Juszczak, Radosław; Celesti, Marco; Rossini, Micol; Haworth, Matthew; Campbell, Benjamin W; Mevy, Jean-Philippe; Vescovo, Loris; Cendrero-Mateo, M Pilar; Rascher, Uwe; Miglietta, Franco

    2018-03-02

    The photosynthetic, optical, and morphological characteristics of a chlorophyll-deficient (Chl-deficient) "yellow" soybean mutant (MinnGold) were examined in comparison with 2 green varieties (MN0095 and Eiko). Despite the large difference in Chl content, similar leaf photosynthesis rates were maintained in the Chl-deficient mutant by offsetting the reduced absorption of red photons by a small increase in photochemical efficiency and lower non-photochemical quenching. When grown in the field, at full canopy cover, the mutants reflected a significantly larger proportion of incoming shortwave radiation, but the total canopy light absorption was only slightly reduced, most likely due to a deeper penetration of light into the canopy space. As a consequence, canopy-scale gross primary production and ecosystem respiration were comparable between the Chl-deficient mutant and the green variety. However, total biomass production was lower in the mutant, which indicates that processes other than steady state photosynthesis caused a reduction in biomass accumulation over time. Analysis of non-photochemical quenching relaxation and gas exchange in Chl-deficient and green leaves after transitions from high to low light conditions suggested that dynamic photosynthesis might be responsible for the reduced biomass production in the Chl-deficient mutant under field conditions. © 2018 John Wiley & Sons Ltd.

  12. The effects of protein crowding in bacterial photosynthetic membranes on the flow of quinone redox species between the photochemical reaction center and the ubiquinol-cytochrome c2 oxidoreductase.

    Science.gov (United States)

    Woronowicz, Kamil; Sha, Daniel; Frese, Raoul N; Sturgis, James N; Nanda, Vikas; Niederman, Robert A

    2011-08-01

    Atomic force microscopy (AFM) of the native architecture of the intracytoplasmic membrane (ICM) of a variety of species of purple photosynthetic bacteria, obtained at submolecular resolution, shows a tightly packed arrangement of light harvesting (LH) and reaction center (RC) complexes. Since there are no unattributed structures or gaps with space sufficient for the cytochrome bc(1) or ATPase complexes, they are localized in membrane domains distinct from the flat regions imaged by AFM. This has generated a renewed interest in possible long-range pathways for lateral diffusion of UQ redox species that functionally link the RC and the bc(1) complexes. Recent proposals to account for UQ flow in the membrane bilayer are reviewed, along with new experimental evidence provided from an analysis of intrinsic near-IR fluorescence emission that has served to test these hypotheses. The results suggest that different mechanism of UQ flow exist between species such as Rhodobacter sphaeroides, with a highly organized arrangement of LH and RC complexes and fast RC electron transfer turnover, and Phaeospirillum molischianum with a more random organization and slower RC turnover. It is concluded that packing density of the peripheral LH2 antenna in the Rba. sphaeroides ICM imposes constraints that significantly slow the diffusion of UQ redox species between the RC and cytochrome bc(1) complex, while in Phs. molischianum, the crowding of the ICM with LH3 has little effect upon UQ diffusion. This supports the proposal that in this type of ICM, a network of RC-LH1 core complexes observed in AFM provides a pathway for long-range quinone diffusion that is unaffected by differences in LH complex composition or organization.

  13. Selective binding of carotenoids with a shorter conjugated chain to the LH2 antenna complex and those with a longer conjugated chain to the reaction center from Rubrivivax gelatinosus.

    Science.gov (United States)

    Kakitani, Yoshinori; Fujii, Ritsuko; Hayakawa, Yoshihiro; Kurahashi, Masahiro; Koyama, Yasushi; Harada, Jiro; Shimada, Keizo

    2007-06-19

    Rubrivivax gelatinosus having both the spheroidene and spirilloxanthin biosynthetic pathways produces carotenoids (Cars) with a variety of conjugated chains, which consist of different numbers of conjugated double bonds (n), including the C=C (m) and C=O (o) bonds. When grown under anaerobic conditions, the wild type produces Cars for which n = m = 9-13, whereas under semiaerobic conditions, it additionally produces Cars for which n = m + o = 10 + 1, 13 + 1, and 13 + 2. On the other hand, a mutant, in which the latter pathway is genetically blocked, produces only Cars for which n = 9 and 10 under anaerobic conditions and n = 9, 10, and 10 + 1 under semianaerobic conditions. Those Cars that were extracted from the LH2 complex (LH2) and the reaction center (RC), isolated from the wild-type and the mutant Rvi. gelatinosus, were analyzed by HPLC, and their structures were determined by mass spectrometry and 1H NMR spectroscopy. The selective binding of Cars to those pigment-protein complexes has been characterized as follows. (1) Cars with a shorter conjugated chain are selectively bound to LH2 whereas Cars with a longer conjugated chain to the RC. (2) Shorter chain Cars with a hydroxyl group are bound to LH2 almost exclusively. This rule holds either in the absence or in the presence of the keto group. The natural selection of shorter chain Cars by LH2 and longer chain Cars by the RC is discussed, on the basis of the results now available, in relation to the light-harvesting and photoprotective functions of Cars.

  14. Comparison of Path Length and Ranges of Movement of the Center of Pressure and Reaction Time and Between Paired-Play and Solo-Play of a Virtual Reality Game.

    Science.gov (United States)

    Portnoy, Sigal; Hersch, Ayelet; Sofer, Tal; Tresser, Sarit

    2017-06-01

    To test whether paired-play will induce longer path length and ranges of movement of the center of pressure (COP), which reflects on balance performance and stability, compared to solo-play and to test the difference in the path length and ranges of movement of the COP while playing the virtual reality (VR) game with the dominant hand compared to playing it with the nondominant hand. In this cross-sectional study 20 children (age 6.1 ± 0.7 years old) played an arm movement controlled VR game alone and with a peer while each of them stood on a pressure measuring pad to track the path length and ranges of movement of the COP. The total COP path was significantly higher during the paired-play (median 295.8 cm) compared to the COP path during the solo-play (median 189.2 cm). No significant differences were found in the reaction time and the mediolateral and anterior-posterior COP ranges between solo-play and paired-play. No significant differences were found between the parameters extracted during paired-play with the dominant or nondominant hand. Our findings imply that the paired-play is advantageous compared to solo-play since it induces a greater movement for the child, during which, higher COP velocities are reached that may contribute to improving the balance control of the child. Apart from the positive social benefits of paired-play, this positive effect on the COP path length is a noteworthy added value in the clinical setting when treating children with balance disorder.

  15. An evaluation of the problems of chlorophyll retrieval from ocean colour, for case 2 waters

    Digital Repository Service at National Institute of Oceanography (India)

    Sathyendranath, S.; Prieur, L.; Morel, A.

    A reflectance model is presented that takes into account the spectral signatures of phytoplankton, dissolved organic matter and non-chlorophyllous particles. The model is validated by comparison with observed reflectance spectra. It is then used...

  16. Chlorophyll-a, Aqua MODIS, NPP, 0.0125 degrees, Indonesia

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA CoastWatch distributes chlorophyll-a concentration data from NASA's Aqua Spacecraft. Measurements are gathered by the Moderate Resolution Imaging...

  17. Chlorophyll-a, Aqua MODIS, OSU DB, 0.0125 degrees, West US

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA CoastWatch distributes chlorophyll-a concentration data from NASA's Aqua satellite. Measurements are gathered by the Moderate Resolution Imaging...

  18. Chlorophyll-a, Aqua MODIS, NPP, 0.025 degrees, Pacific Ocean, EXPERIMENTAL

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA CoastWatch distributes chlorophyll-a concentration data from NASA's Aqua Spacecraft. Measurements are gathered by the Moderate Resolution Imaging...

  19. Chlorophyll-a, Aqua MODIS, NPP, 0.0125 degrees, Gulf of Mexico, EXPERIMENTAL

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA CoastWatch distributes chlorophyll-a concentration data from NASA's Aqua Spacecraft. Measurements are gathered by the Moderate Resolution Imaging...

  20. Chlorophyll-a, Aqua MODIS, NPP, 0.05 degrees, Global, Science Quality

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA CoastWatch distributes chlorophyll-a concentration data from NASA's Aqua Spacecraft. Measurements are gathered by the Moderate Resolution Imaging...

  1. Chlorophyll-a, Aqua MODIS, NPP, 0.0125 degrees, East US, EXPERIMENTAL

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA CoastWatch distributes chlorophyll-a concentration data from NASA's Aqua Spacecraft. Measurements are gathered by the Moderate Resolution Imaging...

  2. Chlorophyll-a, Aqua MODIS, NPP, 0.0125 degrees, West US, EXPERIMENTAL

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA CoastWatch distributes chlorophyll-a concentration data from NASA's Aqua Spacecraft. Measurements are gathered by the Moderate Resolution Imaging...

  3. TRACKING CHANGES IN CHLOROPHYLL AND CAROTENOIDS IN THE PRODUCTION PROCESS OF FROZEN SPINACH PURÉE

    Directory of Open Access Journals (Sweden)

    Andrea Mendelová

    2014-02-01

    Full Text Available Spinach is in the professional and general public considered highly nutritious vegetable with many beneficial effects on human health. It is a rich source of antioxidant active substances, especially chlorophyll, carotenoids, flavonoids and minerals especially zinc and copper. This work studies the changes of chlorophyll and carotenoids that occur after mass production technology of freezing at -37 °C. Before freezing was used blanching operation. In this work we used a variety Boeing, Boa, Beaver, Hudson and Chica. The highest content of all monitored parameters are found in fresh leaves of sampled Hudson. We found that within the processing decreases chlorophyll in 16.6%, 13.8% of chlorophyll b and carotenoids of 6.15%. This decrease was in all cases statistically significant.

  4. Seasonal variability of sea surface chlorophyll-a of waters around ...

    Indian Academy of Sciences (India)

    days during 1978--1986 are processed to produce sea surface chlorophyll maps ... shallow water areas, in particular waters in Palk Bay and Gulf of Mannar, should be carried out in order .... The circulation penetrates deeper, affecting the.

  5. Chlorophyll 'a' particulate organic carbon and suspended load from the mangrove areas of Cochin backwaters

    Digital Repository Service at National Institute of Oceanography (India)

    Sheeba, P.; Devi, K.S.; Balasubramanian, T.; Sankaranarayanan, V.N.

    Chlorophyll 'a' Particulate Organic Carbon and suspended load were estimated for one year from two distinct mangrove areas of Cochin backwaters, viz. Puthuvypeen and Nettoor. Environmental parameters like tau degrees C, S ppt and pH were also...

  6. HAAR TRANSFORM BASED ESTIMATION OF CHLOROPHYLL AND STRUCTURE OF THE LEAF

    OpenAIRE

    Abhinav Arora; R. Menaka; Shivangi Gupta; Archit Mishra

    2013-01-01

    In this paper, the health of a plant is estimated using various non-destructive Image Processing Techniques. Chlorophyll content was detected based on colour Image Processing. The Haar transform is applied to get size of leaf and the parameters.

  7. Comparison of chlorophyll in the Red Sea derived from MODIS-Aqua and in vivo fluorescence

    KAUST Repository

    Brewin, Robert J W; Raitsos, Dionysios E.; Pradhan, Yaswant; Hoteit, Ibrahim

    2013-01-01

    The Red Sea is a unique marine environment but relatively unexplored. The only available long-term biological dataset at large spatial and temporal scales is remotely-sensed chlorophyll observations (an index of phytoplankton biomass) derived using

  8. Effect of gamma radiation on chlorophylls content, net photosynthesis and respiration of Chlorella pyrenoidosa

    International Nuclear Information System (INIS)

    Martin Moreno, C.; Fernandez Gonzalez, J.

    1983-01-01

    The effect of five doses of gamma radiation: 10, 100, 500, 1000 and 5000 Gy on chlorophylls content, net photosynthesis and respiration of Chlorella pyrenoidosa has been studied. A decrease in chlorophylls levels is produced after irradiation at 500, 1000 and 5000 Gy, being, at first b chlorophyll affected to a greater extent than a chlorophyll. Net photosynthesis and respiration decline throughout the time of the observation after irradiation, this depressing effect being much more remarkable for the first one. Met photosynthesis inhibition levels of about 30% are got only five hours post irradiation at a dose of 5000 Gy. Radio estimation by low doses, although obtained in some cases for tho 10 Gy dose, has not been statistically confirmed. (Author) 23 refs

  9. Chlorophyll Detection and Mapping of Shallow Water Impoundments Using Image Spectrometry

    International Nuclear Information System (INIS)

    Artigas, F.; Pechmann, I.; Marti, A.; Yao, N.; Pechmann, I.

    2008-01-01

    There exists a common perception that chlorophyll a concentrations in tidal coastal waters are unsuitable to be captured by remote sensing techniques because of high water turbidity. In this study, we use band index measurements to separate active chlorophyll pigments from other constituents in the water. Published single- and multiband spectral indices are used to establish a relationship between algal chlorophyll concentration and reflectance data. We find an index which is suitable to map chlorophyll gradients in the impoundments, ditches, and associated waterways of the Hackensack Meadow lands (NJ, USA). The resulting images clearly depict the spatial distribution of plant pigments and their relationship with the biological conditions of the waters in the estuary. Since these biological conditions are often determined by land usage, the methods in this paper provide a simple tool to address water quality management issues in fragmented urban estuaries.

  10. Are the Satellite-Observed Narrow, Streaky Chlorophyll Filaments Locally Intensified by the Submesoscale Processes?

    Science.gov (United States)

    2015-11-05

    HIS I’OR’A CANCELS AND SUPERSEOFS Al l PRFV•OUS VERSIONS ARE THE SATELLITE-OBSERVED NARROW, STREAKY CHLOROPHYLL FILAMENTS LOCALLY INTENSIFIED BY...AUGUST 2003 cold, dense jeto C 17 16 15 14 13 122.4W 122W 122.4W 122W warm, anticyclonic eddy CHLOROPHYLL 122.4W 122W 122.4W 122W 122.4W 122W filament...122.4W 122W mg/m 3 10 4 2 1 0.4 0.2 Figure 1. MODIS-Aqua SST and Chlorophyll a images for August 2003. Black lines on MODIS SST and Chlorophyll a

  11. Chlorophyll catalyse the photo-transformation of carcinogenic benzo[a]pyrene in water

    Science.gov (United States)

    Luo, Lijuan; Lai, Xueying; Chen, Baowei; Lin, Li; Fang, Ling; Tam, Nora F. Y.; Luan, Tiangang

    2015-01-01

    Algal blooms cause great damage to water quality and aquaculture. However, this study showed that dead algal cells and chlorophyll could accelerate the photo-transformation of benzo[a]pyrene (BaP), a ubiquitous and persistent pollutant with potently mutagenic and carcinogenic toxicities, under visible light irradiation. Chlorophyll was found to be the major active substance in dead algal cells, and generated a high level of singlet oxygen to catalyse the photo-transformation of BaP. According to various BaP metabolites formed, the degradation mechanism was proposed as that chlorophyll in dead algal cells photo-oxidized BaP to quinones via photocatalytic generation of singlet oxygen. The results provided a good insight into the role of chlorophyll in the photo-transformation of organic contaminants and could be a possible remediation strategy of organic pollutants in natural environment. PMID:26239357

  12. Mutagentic effects of aerospace on Poa pratensis L.. Pt.2: Photosynthesis characters and chlorophyll contents

    International Nuclear Information System (INIS)

    Han Lei; Sun Zhenyuan; Ju Guansheng; Qian Yongqiang; Li Yinfeng; Peng Zhenhua

    2005-01-01

    The dry seeds of Poa pratensis L. 'Nassau' were carried by 'Shenzhou No.3' and three mutants were screened based on presentational characters from the treated plants and asexual reproduced them as PM 1 , PM 2 and PM 3 . The effects of the space environment on the photosynthesis characters and the contents of chlorophyll of the plants were investigated. Compared to CK, the contents of the chlorophyll a and b were reduced both in PM 1 and PM 3 , and the photosynthetic ability also decreased. The content of the chlorophyll in PM 2 increased greatly, but the ratio of the chlorophyll a/b was reduced, and the apparent quantum efficiency and the photosynthetic ability also decreased. The approximately CO 2 saturation point of the three mutants were higher than CK, but the CO 2 compensation points showed no difference between the mutants and CK. The carboxylation efficiency was PM 2 3 1 . (authors)

  13. An FTIR study on the chlorophyll and apoprotein aggregation states in LHCII due to solvent effects

    CSIR Research Space (South Africa)

    Smit, Jacoba E

    2012-07-01

    Full Text Available Photosynthesis provides us with the most abundant and efficient light-harvesting systems found in nature. The photosynthetic process is very much dependent on the aggregation state of the chlorophylls and secondary conformational structure...

  14. Relationships between Concentrations of Phytoplankton Chlorophyll a and Total Nitrogen in Ten U.S. Estuaries

    Science.gov (United States)

    This presentation focuses on the summertime response of phytoplankton chlorophyll to nitrogen concentrations in the upper water columns of ten U.S. estuaries. Using publicly available data from monitoring programs, regression relationships have been developed between summer surfa...

  15. VIIRSN Level-3 Standard Mapped Image, Chlorophyll a, Daily, 4km

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA CoastWatch distributes chlorophyll-a concentration data from the NPP -Suonomi Spacecraft. Measurements are gathered by the VIIRS instrument carried aboard the...

  16. Five Year Mean Surface Chlorophyll Estimates in the Northern Gulf of Mexico for 2005 through 2009

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These images were created by combining the mean surface chlorophyll estimates to produce seasonal representations for winter, spring, summer and fall. Winter...

  17. Subsurface chlorophyll maxima in the north-western Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Sarma, V.V.; Aswanikumar, V.

    of thermocline suggests that the formation of the subsurface maximum is influencEd. by the presence of seasonal thermocline. Further the subsurface chlorophyll maximum is noticed within the depth ranges of ammonium maximum and nitracline, suggesting...

  18. Chlorophyll-a, Terra MODIS, OSU DB, 0.0125 degrees, West US, EXPERIMENTAL

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA CoastWatch distributes chlorophyll-a concentration data from NASA's Terra satellite. Measurements are gathered by the Moderate Resolution Imaging...

  19. Thermocline Regulated Seasonal Evolution of Surface Chlorophyll in the Gulf of Aden

    KAUST Repository

    Hoteit, Ibrahim; Yao, Fengchao

    2015-01-01

    The Gulf of Aden, although subject to seasonally reversing monsoonal winds, has been previously reported as an oligotrophic basin during summer, with elevated chlorophyll concentrations only occurring during winter due to convective mixing. However

  20. Extraction of chlorophyll from pandan leaves using ethanol and mass transfer study

    Directory of Open Access Journals (Sweden)

    Putra Meilana Dharma

    2017-01-01

    Full Text Available Green pigments are used in many industrial branches including food, drinks, soap and cosmetics. Chlorophyll can substitute synthetic dyes which may affect health. Chlorophyll can be extracted from pandan leaves; the pandan crop grows in many tropical areas. The effects of temperature, 30–70°C and agitation speed, 100–400 rpm on chlorophyll extraction from pandan leaves, using ethanol and the evaluation of mass transfer coefficient, using dimensionless analysis were investigated. The optimal conditions of extraction was obtained at 60°C and 300 rpm; the chlorophyll concentration was 107.1 mg L-1. The volumetric mass transfer coefficient increased with the temperature and agitation speed. Determination of volumetric mass transfer coefficient and dimensionless correlations are useful for further process development or industrial applications.

  1. Vegetation chlorophyll estimates in the Amazon from multi-angle MODIS observations and canopy reflectance model

    Science.gov (United States)

    Hilker, Thomas; Galvão, Lênio Soares; Aragão, Luiz E. O. C.; de Moura, Yhasmin M.; do Amaral, Cibele H.; Lyapustin, Alexei I.; Wu, Jin; Albert, Loren P.; Ferreira, Marciel José; Anderson, Liana O.; dos Santos, Victor A. H. F.; Prohaska, Neill; Tribuzy, Edgard; Barbosa Ceron, João Vitor; Saleska, Scott R.; Wang, Yujie; de Carvalho Gonçalves, José Francisco; de Oliveira Junior, Raimundo Cosme; Cardoso Rodrigues, João Victor Figueiredo; Garcia, Maquelle Neves

    2017-06-01

    As a preparatory study for future hyperspectral missions that can measure canopy chemistry, we introduce a novel approach to investigate whether multi-angle Moderate Resolution Imaging Spectroradiometer (MODIS) data can be used to generate a preliminary database with long-term estimates of chlorophyll. MODIS monthly chlorophyll estimates between 2000 and 2015, derived from a fully coupled canopy reflectance model (ProSAIL), were inspected for consistency with eddy covariance fluxes, tower-based hyperspectral images and chlorophyll measurements. MODIS chlorophyll estimates from the inverse model showed strong seasonal variations across two flux-tower sites in central and eastern Amazon. Marked increases in chlorophyll concentrations were observed during the early dry season. Remotely sensed chlorophyll concentrations were correlated to field measurements (r2 = 0.73 and r2 = 0.98) but the data deviated from the 1:1 line with root mean square errors (RMSE) ranging from 0.355 μg cm-2 (Tapajós tower) to 0.470 μg cm-2 (Manaus tower). The chlorophyll estimates were consistent with flux tower measurements of photosynthetically active radiation (PAR) and net ecosystem productivity (NEP). We also applied ProSAIL to mono-angle hyperspectral observations from a camera installed on a tower to scale modeled chlorophyll pigments to MODIS observations (r2 = 0.73). Chlorophyll pigment concentrations (ChlA+B) were correlated to changes in the amount of young and mature leaf area per month (0.59 ≤ r2 ≤ 0.64). Increases in MODIS observed ChlA+B were preceded by increased PAR during the dry season (0.61 ≤ r2 ≤ 0.62) and followed by changes in net carbon uptake. We conclude that, at these two sites, changes in LAI, coupled with changes in leaf chlorophyll, are comparable with seasonality of plant productivity. Our results allowed the preliminary development of a 15-year time series of chlorophyll estimates over the Amazon to support canopy chemistry studies using future

  2. DAYTIME VARIATIONS OF CHLOROPHYLL A FLUORESCENCE IN PAU D'ALHO SEEDLINGS

    OpenAIRE

    Bacarin, Marcos Antonio; Martinazzo, Emanuela Garbin; Cassol, Daniela; Falqueto, Antelmo Ralph; Silva, Diolina Moura

    2016-01-01

    ABSTRACT Analysis of transient and modulated fluorescence of chlorophyll a were made at one-hour intervals during an eight-hour period starting at 07:30h aiming to study mechanisms of photoprotection against high radiation and temperature in Gallesia integrifolia plants. Seeds were germinated inside plastic pots containing soil as substrate. At 120 days after emergence, chlorophyll fluorescence measurements were performed using Handy-PEA and FMS2 fluorometers. During the course of a day, an i...

  3. Impact of measurement uncertainties on determination of chlorophyll-specific absorption coefficient for marine phytoplankton

    OpenAIRE

    McKee, D.; Röttgers, R.; Neukermans, G.; Calzado, V.S.; Trees, C.; Ampolo-Rella, M.; Neil, C.; Cunningham, A.

    2014-01-01

    Understanding variability in the chlorophyll-specific absorption of marine phytoplankton, aph*Chl (λ), is essential for primary production modelling, calculation of underwater light field characteristics, and development of algorithms for remote sensing of chlorophyll concentrations. Previous field and laboratory studies have demonstrated significant apparent variability in aph*Chl (λ) for natural samples and algal cultures. However, the potential impact of measurement uncertain...

  4. Characterization of [8-ethyl]-chlorophyll c3 from Emiliania huxleyi.

    Science.gov (United States)

    Álvarez, Susana; Zapata, Manuel; Garrido, José L; Vaz, Belén

    2012-06-04

    We report herein the isolation and complete characterization of a member of the chlorophyll c family, designated as [8-ethyl]-chlorophyll c(3) ([8-ethyl]-chl c(3)). Structural elucidation of this pigment rested on the analysis of mono- and bidimensional NMR, UV-VIS spectroscopy and ESI-MS data, and the configuration at the 13(2) position on chiral HPLC analysis.

  5. PIXE analysis of trace elements in relation to chlorophyll concentration in Plantago ovata Forsk

    International Nuclear Information System (INIS)

    Saha, Priyanka; Sen Raychaudhuri, Sarmistha; Chakraborty, Anindita; Sudarshan, Mathummal

    2010-01-01

    Plantago ovata Forsk - an economically important medicinal plant - was analyzed for trace elements and chlorophyll in a study of the effects of gamma radiation on physiological responses of the seedlings. Proton-induced X-ray emission (PIXE) technique was used to quantify trace elements in unirradiated and gamma-irradiated plants at the seedling stage. The experiments revealed radiation-induced changes in the trace element and chlorophyll concentrations.

  6. Trends in Ocean Colour and Chlorophyll Concentration from 1889 to 2000, Worldwide

    Science.gov (United States)

    Wernand, Marcel R.; van der Woerd, Hendrik J.; Gieskes, Winfried W. C.

    2013-01-01

    Marine primary productivity is an important agent in the global cycling of carbon dioxide, a major ‘greenhouse gas’, and variations in the concentration of the ocean's phytoplankton biomass can therefore explain trends in the global carbon budget. Since the launch of satellite-mounted sensors globe-wide monitoring of chlorophyll, a phytoplankton biomass proxy, became feasible. Just as satellites, the Forel-Ule (FU) scale record (a hardly explored database of ocean colour) has covered all seas and oceans – but already since 1889. We provide evidence that changes of ocean surface chlorophyll can be reconstructed with confidence from this record. The EcoLight radiative transfer numerical model indicates that the FU index is closely related to chlorophyll concentrations in open ocean regions. The most complete FU record is that of the North Atlantic in terms of coverage over space and in time; this dataset has been used to test the validity of colour changes that can be translated to chlorophyll. The FU and FU-derived chlorophyll data were analysed for monotonously increasing or decreasing trends with the non-parametric Mann-Kendall test, a method to establish the presence of a consistent trend. Our analysis has not revealed a globe-wide trend of increase or decrease in chlorophyll concentration during the past century; ocean regions have apparently responded differentially to changes in meteorological, hydrological and biological conditions at the surface, including potential long-term trends related to global warming. Since 1889, chlorophyll concentrations have decreased in the Indian Ocean and in the Pacific; increased in the Atlantic Ocean, the Mediterranean, the Chinese Sea, and in the seas west and north-west of Japan. This suggests that explanations of chlorophyll changes over long periods should focus on hydrographical and biological characteristics typical of single ocean regions, not on those of ‘the’ ocean. PMID:23776435

  7. Chlorophyll b Reductase Plays an Essential Role in Maturation and Storability of Arabidopsis Seeds1[W

    Science.gov (United States)

    Nakajima, Saori; Ito, Hisashi; Tanaka, Ryouichi; Tanaka, Ayumi

    2012-01-01

    Although seeds are a sink organ, chlorophyll synthesis and degradation occurs during embryogenesis and in a manner similar to that observed in photosynthetic leaves. Some mutants retain chlorophyll after seed maturation, and they are disturbed in seed storability. To elucidate the effects of chlorophyll retention on the seed storability of Arabidopsis (Arabidopsis thaliana), we examined the non-yellow coloring1 (nyc1)/nyc1-like (nol) mutants that do not degrade chlorophyll properly. Approximately 10 times more chlorophyll was retained in the dry seeds of the nyc1/nol mutant than in the wild-type seeds. The germination rates rapidly decreased during storage, with most of the mutant seeds failing to germinate after storage for 23 months, whereas 75% of the wild-type seeds germinated after 42 months. These results indicate that chlorophyll retention in the seeds affects seed longevity. Electron microscopic studies indicated that many small oil bodies appeared in the embryonic cotyledons of the nyc1/nol mutant; this finding indicates that the retention of chlorophyll affects the development of organelles in embryonic cells. A sequence analysis of the NYC1 promoter identified a potential abscisic acid (ABA)-responsive element. An electrophoretic mobility shift assay confirmed the binding of an ABA-responsive transcriptional factor to the NYC1 promoter DNA fragment, thus suggesting that NYC1 expression is regulated by ABA. Furthermore, NYC1 expression was repressed in the ABA-insensitive mutants during embryogenesis. These data indicate that chlorophyll degradation is induced by ABA during seed maturation to produce storable seeds. PMID:22751379

  8. Non-invasive method for in vivo detection of chlorophyll precursors

    DEFF Research Database (Denmark)

    Kristiansen, Kim Anker; Khrouchtchova, Anastassia; Stenbæk, Anne

    2009-01-01

    Traditionally chlorophyll (Chl) and Chl precursors have been studied in vitro or in leaf tissue at low temperature. These methods are destructive and make it impossible to work with the same individual plant later on. In this paper we present a method for in vivo detection of Chl and its precursors...... is compared to current methods. Furthermore, we report on optimization of the spectral scanning method with the aim to minimize the excitation light-evoked photo-conversion of the chlorophyll precursors....

  9. Genetic Analysis and Molecular Mapping of a Novel Chlorophyll-Deficit Mutant Gene in Rice

    Directory of Open Access Journals (Sweden)

    Xiao-qun HUANG

    2008-03-01

    Full Text Available A rice etiolation mutant 824ys featured with chlorophyll deficiency was identified from a normal green rice variety 824B. It showed whole green-yellow plant from the seedling stage, reduced number of tillers and longer growth duration. The contents of chlorophyll, chlorophyll a, chlorophyll b and net photosynthetic rate in leaves of the mutant obviously decreased, as well as the number of spikelets per panicle, seed setting rate and 1000-grain weight compared with its wild-type parent. Genetic analyses on F1 and F2 generations of 824ys crossed with three normal green varieties showed that the chlorophyll-deficit mutant character was controlled by a pair of recessive nuclear gene. Genetic mapping of the mutant gene was conducted by using microsatellite markers and F2 mapping population of 495R/824ys, and the mutant gene of 824ys was mapped on the short arm of rice chromosome 3. The genetic distances from the target gene to the markers RM218, RM282 and RM6959 were 25.6 cM, 5.2 cM and 21.8 cM, respectively. It was considered to be a new chlorophyll-deficit mutant gene and tentatively named as chl11(t.

  10. Contribution of Co2+ in increasing chlorophyll a concentration of Nannochloropsis salina in controlled Conwy medium

    Science.gov (United States)

    Hala, Y.; Taba, P.; Suryati, E.; Kasih, P.; Firman, N. F.

    2018-03-01

    A research in determining the contribution of Co2+ on the increase of chlorophyll a concentration of Nannochloropsis salina has been caried out. The cultivation of N. salina was conducted in the Conwy medium with a salinity of 5%o and 25%o and various Co2+ concentration (2, 4, and 8 ppm). In this research, Co2+ was exposed early in the cultivation of N. salina. The growth of N. salina was observed daily by counting the number of populations using a haemocytometer while the chlorophyll a concentration was determined by a Uv-Vis spectrophotometer. The results showed that the growth of N. salina in the control was higher than that in the medium containing Co2+. The optimum growth time was achieved on 15th days (5%) and 8th days (25%). In the cultivation medium with a salinity of 5%, Co2+ with a concentration of 2 ppm increased the chlorophyll a level while Co2+ with concentrations of 4 and 8 ppm decreased it. In the medium of cultivation with a salinity of 25%, the increase in chlorophyll a level was observed at Co2+ concentrations of 2 and 4 ppm whereas the decrease in chlorophyl a level was given at a concentration of 8 ppm. It can be concluded that at low concentrations, Co2+ increased the concentration of chlorophyll a in N. salina.

  11. Spatial-temporal variability of leaf chlorophyll and its relationship with cocoa yield

    Directory of Open Access Journals (Sweden)

    Caique C. Medauar

    Full Text Available ABSTRACT The objective of this study was to evaluate the spatial-temporal variability of leaf chlorophyll index and its relationship with cocoa yield. The experiment was carried out in an experimental area of cocoa production located in Ilhéus, Bahia State, Brazil. Leaf chlorophyll content was measured in September, October, January, February, March and April in the 2014/2015 season, at each sampling point of a regular grid by using a portable chlorophyll meter. Under the same conditions, yield was evaluated and the data were submitted to descriptive statistics and a linear correlation study. Geostatistical analysis was used to determine and quantify the spatial and temporal variability of leaf chlorophyll index and yield. Leaf chlorophyll index varied over the period evaluated, but the months of February, March and April showed no spatial dependence in the study area, indicating absence of temporal stability. Cocoa monthly yield, except in January, presented high spatial variability. Under the conditions of this study, it was not possible to establish a relationship between leaf chlorophyll index and cocoa yield.

  12. Estimating chlorophyll content of spartina alterniflora at leaf level using hyper-spectral data

    Science.gov (United States)

    Wang, Jiapeng; Shi, Runhe; Liu, Pudong; Zhang, Chao; Chen, Maosi

    2017-09-01

    Spartina alterniflora, one of most successful invasive species in the world, was firstly introduced to China in 1979 to accelerate sedimentation and land formation via so-called "ecological engineering", and it is now widely distributed in coastal saltmarshes in China. A key question is how to retrieve chlorophyll content to reflect growth status, which has important implication of potential invasiveness. In this work, an estimation model of chlorophyll content of S. alterniflora was developed based on hyper-spectral data in the Dongtan Wetland, Yangtze Estuary, China. The spectral reflectance of S. alterniflora leaves and their corresponding chlorophyll contents were measured, and then the correlation analysis and regression (i.e., linear, logarithmic, quadratic, power and exponential regression) method were established. The spectral reflectance was transformed and the feature parameters (i.e., "san bian", "lv feng" and "hong gu") were extracted to retrieve the chlorophyll content of S. alterniflora . The results showed that these parameters had a large correlation coefficient with chlorophyll content. On the basis of the correlation coefficient, mathematical models were established, and the models of power and exponential based on SDb had the least RMSE and larger R2 , which had a good performance regarding the inversion of chlorophyll content of S. alterniflora.

  13. Dustfall Effect on Hyperspectral Inversion of Chlorophyll Content - a Laboratory Experiment

    Science.gov (United States)

    Chen, Yuteng; Ma, Baodong; Li, Xuexin; Zhang, Song; Wu, Lixin

    2018-04-01

    Dust pollution is serious in many areas of China. It is of great significance to estimate chlorophyll content of vegetation accurately by hyperspectral remote sensing for assessing the vegetation growth status and monitoring the ecological environment in dusty areas. By using selected vegetation indices including Medium Resolution Imaging Spectrometer Terrestrial Chlorophyll Index (MTCI) Double Difference Index (DD) and Red Edge Position Index (REP), chlorophyll inversion models were built to study the accuracy of hyperspectral inversion of chlorophyll content based on a laboratory experiment. The results show that: (1) REP exponential model has the most stable accuracy for inversion of chlorophyll content in dusty environment. When dustfall amount is less than 80 g/m2, the inversion accuracy based on REP is stable with the variation of dustfall amount. When dustfall amount is greater than 80 g/m2, the inversion accuracy is slightly fluctuation. (2) Inversion accuracy of DD is worst among three models. (3) MTCI logarithm model has high inversion accuracy when dustfall amount is less than 80 g/m2; When dustfall amount is greater than 80 g/m2, inversion accuracy decreases regularly and inversion accuracy of modified MTCI (mMTCI) increases significantly. The results provide experimental basis and theoretical reference for hyperspectral remote sensing inversion of chlorophyll content.

  14. Effect of PEG-6000 Imposed Water Deficit on Chlorophyll Metabolism in Maize Leaves

    Directory of Open Access Journals (Sweden)

    Rekha Gadre

    2013-08-01

    Full Text Available Drought stress is one of the major abiotic constraint limiting plant growth and productivity world wide. The current study was undertaken with the aim to investigate the effect of water deficit imposed by PEG-6000, on chlorophyll metabolism in maize leaves to work out the mechanistic details. Leaf segments prepared from primary leaves of etiolated maize seedlings were treated with varying concentrations of polyethylene glycol-6000 (PEG-6000; w/v- 5%, 10%, 20%, 30% in continuous light of intensity 40 Wm-2 at 26±2 °C for 24 h in light chamber. The results demonstrate a concentration dependent decline in chlorophyll content with increasing concentration of polyethylene glycol-6000 (PEG-6000. Reduction in chlorophyll ‘a’ level was to a greater extent than the chlorophyll ‘b’. The RNA content decreased in a concentration dependent manner with PEG, however, proline content increased significantly. Relative water content decreased significantly with the supply of 30% PEG only. A substantial decrease in chlorophyll synthesis due to significant reduction in ALA content and ALAD activity, with no change in chlorophyllase activity with the supply of PEG suggests that water deficit affects chlorophyll formation rather than its degradation.

  15. Chlorophyll and carbohydrates in Arachis pintoi plants under influence of water regimes and nitrogen fertilization

    Directory of Open Access Journals (Sweden)

    Rita Manuele Porto Sales

    2013-06-01

    Full Text Available In this experiment the chlorophyll and carbohydrate contents of Arachis pintoi were evaluated to verify if the presence of nitrogen in the soil could contribute to the effectiveness of the establishment of this legume. The design was completely randomized, in a 4 × 4 factorial arrangement, with four N rates (0, 40, 80 and 120 kg ha-1 and four irrigation levels (25, 50, 75 and 100% of field capacity, with four replications. The biochemical evaluations of chlorophylls a and b and total chlorophyll and total soluble sugars, sucrose and starch were performed. The highest contents of chlorophyll a and b and total chlorophyll in leaves were found at the dose of 120 kg ha-1. The water regime of 25% of field capacity was responsible for the lowest content of reducing sugars and total soluble sugars in leaves, stolons and roots. In the roots, the sucrose contents were higher in these conditions, which can be associated with a slight tolerance of the plant to water stress. The water deficiency was responsible for the decrease of reducing sugars and total N in the whole plant and positively influenced the levels of chlorophyll and sugars in the stolon, promoting growth, especially of shoots, at the beginning of establishment.

  16. Spatiotemporal Variation in Mangrove Chlorophyll Concentration Using Landsat 8

    Directory of Open Access Journals (Sweden)

    Julio Pastor-Guzman

    2015-11-01

    Full Text Available There is a need to develop indicators of mangrove condition using remotely sensed data. However, remote estimation of leaf and canopy biochemical properties and vegetation condition remains challenging. In this paper, we (i tested the performance of selected hyperspectral and broad band indices to predict chlorophyll concentration (CC on mangrove leaves and (ii showed the potential of Landsat 8 for estimation of mangrove CC at the landscape level. Relative leaf CC and leaf spectral response were measured at 12 Elementary Sampling Units (ESU distributed along the northwest coast of the Yucatan Peninsula, Mexico. Linear regression models and coefficients of determination were computed to measure the association between CC and spectral response. At leaf level, the narrow band indices with the largest correlation with CC were Vogelmann indices and the MTCI (R2 > 0.5. Indices with spectral bands around the red edge (705–753 nm were more sensitive to mangrove leaf CC. At the ESU level Landsat 8 NDVI green, which uses the green band in its formulation explained most of the variation in CC (R2 > 0.8. Accuracy assessment between estimated CC and observed CC using the leave-one-out cross-validation (LOOCV method yielded a root mean squared error (RMSE = 15 mg·cm−2, and R2 = 0.703. CC maps showing the spatiotemporal variation of CC at landscape scale were created using the linear model. Our results indicate that Landsat 8 NDVI green can be employed to estimate CC in large mangrove areas where ground networks cannot be applied, and mapping techniques based on satellite data, are necessary. Furthermore, using upcoming technologies that will include two bands around the red edge such as Sentinel 2 will improve mangrove monitoring at higher spatial and temporal resolutions.

  17. Chlorophyll f distribution and dynamics in cyanobacterial beachrock biofilms.

    Science.gov (United States)

    Trampe, Erik; Kühl, Michael

    2016-12-01

    Chlorophyll (Chl) f, the most far-red (720-740 nm) absorbing Chl species, was discovered in cyanobacterial isolates from stromatolites and subsequently in other habitats as well. However, the spatial distribution and temporal dynamics of Chl f in a natural habitat have so far not been documented. Here, we report the presence of Chl f in cyanobacterial beachrock biofilms. Hyperspectral imaging on cross-sections of beachrock from Heron Island (Great Barrier Reef, Australia), showed a strong and widely distributed signature of Chl f absorption in an endolithic layer below the dense cyanobacterial surface biofilm that could be localized to aggregates of Chroococcidiopsis-like unicellular cyanobacteria packed within a thick common sheath. High-pressure liquid chromatography-based pigment analyses showed in situ ratios of Chl f to Chl a of 5% in brown-pigmented zones of the beachrock, with lower ratios of ~0.5% in the black- and pink-pigmented biofilm zones. Enrichment experiments with black beachrock biofilm showed stimulated synthesis of Chl f and Chl d when grown under near-infrared radiation (NIR; 740 nm), with a Chl f to Chl a ratio increasing 4-fold to 2%, whereas the Chl d to Chl a ratio went from 0% to 0.8%. Enrichments grown under white light (400-700 nm) produced no detectable amounts of either Chl d or Chl f. Beachrock cyanobacteria thus exhibited characteristics of far-red light photoacclimation, enabling Chl f -containing cyanobacteria to thrive in optical niches deprived of visible light when sufficient NIR is prevalent. © 2016 Phycological Society of America.

  18. Seasonality in sub-surface chlorophyll maxima in the Arabian Sea: Detection by IRS-P4/OCM and implication of it to primary productivity

    Digital Repository Service at National Institute of Oceanography (India)

    Matondkar, S.G.P.; Parab, S.G.; Dwivedi, R.M.

    various seasons. During November at St. 1 surface chlorophyll a was 1.503 mgm-3and subsurface chlorophyll maxima was 12.692 mgm-3. Similarly, at St. 13 surface chlorophyll a was 0.584 mgm-3and surface chlorophyll maxima was 8.517 mgm-3. During upwelling...

  19. Accelerator Center for Energy Research (ACER)

    Data.gov (United States)

    Federal Laboratory Consortium — The Accelerator Center for Energy Research (ACER) exploits radiation chemistry techniques to study chemical reactions (and other phenomena) by subjecting samples to...

  20. Assimilation of remotely sensed chlorophyll fluorescence data into the land surface model CLM4

    Science.gov (United States)

    Wieneke, S.; Ahrends, H. E.; Rascher, U.; Schween, J.; Schickling, A.; Crewell, S.

    2013-12-01

    Photosynthesis is the most important exchange process of CO2 between the atmosphere and the land-surface. Therefore, the prediction of vegetation response to environmental conditions like increasing CO2 concentrations or plant stress is crucial for a reliable prediction of climate change. Photosynthesis is a complex physiological process that consists of numerous bio-physical sub-processes and chemical reactions. Spatial and temporal patterns of photosynthesis depend on dynamic plant-specific adaptation strategies to highly variable environmental conditions. Photosynthesis can be estimated using land-surface models, but, while state-of-the-art models often rely on Plant Functional Type (PFT) specific constants, they poorly simulate the dynamic adaptation of the physiological status of plant canopies in space and time. Remotely sensed sun-induced chlorophyll fluorescence (SICF) gives us now the possibility to estimate the diurnal dynamic vitality of the photosynthetic apparatus at both, the leaf and canopy levels. We installed within the framework of the Transregio32 project (www.tr32.de) automated hyperspectral fluorescence sensors at an agricultural site (winter wheat) in the Rur catchment area in West Germany at the end of July 2012. End of August, additional measurements of SIFC on nearby temperate grassland site (riparian meadow) and on a sugar beet field were performed. Spatial covering SICF data of the region were obtained during a measurement campaign using the newly developed air-borne hyperspectral sensor HyPlant on the 23 and 27 August 2012. SIFC data and data provided by eddy covariance measurements will be used to update certain model parameters that are normally set as constants. First model results demonstrate that the assimilation of SIFC into the Community Land Model 4 (CLM4) will result in a more realistic simulation of plant-specific adaptation strategies and therefore in a more realistic simulation of photosynthesis in space and time.

  1. Quasielastic reactions

    International Nuclear Information System (INIS)

    Henning, W.

    1979-01-01

    Quasielastic reaction studies, because of their capability to microscopically probe nuclear structure, are still of considerable interest in heavy-ion reactions. The recent progress in understanding various aspects of the reaction mechanism make this aim appear closer. The relation between microscopic and macroscopic behavior, as suggested, for example, by the single proton transfer data to individual final states or averaged excitation energy intervals, needs to be explored. It seems particularly useful to extend measurements to higher incident energies, to explore and understand nuclear structure aspects up to the limit of the energy range where they are important

  2. Adaptive changes in chlorophyll content and photosynthetic features to low light in Physocarpus amurensis Maxim and Physocarpus opulifolius "Diabolo".

    Science.gov (United States)

    Zhang, Huihui; Zhong, Haixiu; Wang, Jifeng; Sui, Xin; Xu, Nan

    2016-01-01

    The present study aims to investigate the differences in leaf pigment content and the photosynthetic characteristics under natural and low light intensities between the Chinese native Physocarpus amurensis Maxim and the imported Physocarpus opulifolius "Diabolo" from North America. We aim to discuss the responses and the adaptive mechanism of these two cultivars of Physocarpus to a low light environment. The results show that the specific leaf area (SLA) and the chlorophyll content were significantly increased in the leaves of both Physocarpus cultivars in response to a low light intensity, and the SLA and chlorophyll content were higher in the leaves of low light-treated P. opulifolius "Diabolo" compared with the leaves of low light-treated P. amurensis Maxim. Moreover, the content of anthocyanin was markedly reduced in the leaves of P. opulifolius "Diabolo" under low light intensity, which allowed for a greater capacity of photon capture under the low light condition. Under natural light, the photosynthetic carbon assimilation capacity was greater in the leaves of P. amurensis Maxim compared with the leaves of P. opulifolius "Diabolo" that were rich with anthocyanin. However, in response to low light, AQY, P max, LCP and LSP decreased to a lesser extent in the leaves of P. opulifolius "Diabolo" compared with the leaves of P. amurensis Maxim. These results suggest that P. opulifolius "Diabolo" exhibits a greater ability in adaption to low light, and it is probably related to the relatively higher chlorophyll content and the smaller SLA in the leaves of P. opulifolius "Diabolo." In addition, the low light intensity resulted in a reduced photochemical activity of photosystem (PS) II in the leaves of both Physocarpus, as evidenced by increased values of the relative variable fluorescence at point J and point I on the OJIP curve. This result suggests that the electron acceptor in PS II was the major responsive site to the low light stress in the leaves of both

  3. cycloaddition reactions

    Indian Academy of Sciences (India)

    Unknown

    Molecular Modeling Group, Organic Chemical Sciences, Indian Institute of Chemical Technology,. Hyderabad ... thus obtained are helpful to model the regioselectivity ... compromise to model Diels–Alder reactions involving ...... acceptance.

  4. Chlorophyll-a Concentrations Affected by Discharge and Climate Conditions in Galveston Bay, Texas

    Science.gov (United States)

    Shen, X.; Gao, H.; Zhang, S.

    2017-12-01

    As the transition zones between river and ocean, estuaries face increasing pressure on their ecosystem health due to changes of freshwater quantity and quality—especially under the impacts of population growth, land use/land cover change, and climate change. Located at the northeast of Houston, Galveston Bay is of particular social economic importance for the State of Texas. Its freshwater inflow primarily arises from two rivers, the San Jacinto and the Trinity. While it is well recognized that Chlorophyll a (chla) concentration—an indicator of ecosystem health—is closely linked to river inflows and other environmental factors, no quantitative relationships have been established. The objectives of this study are to identify the spatial-temporal variations of chla, and to investigate the impacts of freshwater inflow and climatic factors on chla variability—so that prediction models can be developed for chla forecasting to provide scientific support for ecological management (in Galveston Bay). A 10-year validated remote sensing dataset is used in this analysis. The results show that chla has higher concentrations near the shoreline, as compared to the center of the bay. Temporally, chla tends to be higher in wet years than in dry years. Similarly, the seasonal fluctuations of chla are more significant during the wet months (from February to May) than the dry months (especially from August to December). Chla in the bay is primarily determined by discharge from the Trinity River in AMJ (April, May, June) and JAS (July, August, September). However, the driving factor is mainly water temperature in OND (October, November, December). In JFM (January, February, March), almost all of the factors (except discharge from the San Jacinto River) show significant correlation with chla. Based on these analyses, a chla prediction model is developed and tested. This result can provide scientific support for coastal environmental management in Galveston Bay, maintaining the

  5. Growth and chlorophyll fluorescence under salinity stress in sugar beet (Beta vulgaris L.

    Directory of Open Access Journals (Sweden)

    Fadi Abbas

    2014-02-01

    Full Text Available This study was carried out in the General Commission for Scientific Agricultural Research (GCSAR, Syria, at Der EzZour Agricultural Research Center, from 2008-2010, to examine the effect of salt conditions on some growth attributes and chlorophyll fluorescence in 10 Sugar Beet (Beta vulgaris L. genotypes under salinity stress. Sugar beet plants were irrigated with saline water, having electrical conductivity ranged from 8.6-10 dS.m-1during first year and 8.4-10.4 dS.m-1 during second year. A randomized completely block design with three replicates was used. The results showed that all studied growth attributes, leaf area, leaf number, relative growth rate, and net assimilation rate were decreased in salinity stress conditions compared to the controlled state. The findings indicated that salinity caused a decrement of light utilizing through increased values of fluorescence origin (fo, decreased values of fluorescence maximum (fm, and maximum yield of quantum in photosystem-II (fv/fm. Genotypes differed significantly in all studied attributes except in leaf number. Under salt conditions, Brigitta (monogerm achieved an increase in net assimilation rate, while Kawimera (multigerm achieved the lowest decrement in quantum yield in photosystem-II. Further studies are necessary to correlate the yield with yield components under similar conditions to determine the most tolerant genotype.International Journal of Environment Vol.3(1 2014: 1-9 DOI: http://dx.doi.org/10.3126/ije.v3i1.9937

  6. Consistency Between Sun-Induced Chlorophyll Fluorescence and Gross Primary Production of Vegetation in North America

    Science.gov (United States)

    Zhang, Yao; Xiao, Xiangming; Jin, Cui; Dong, Jinwei; Zhou, Sha; Wagle, Pradeep; Joiner, Joanna; Guanter, Luis; Zhang, Yongguang; Zhang , Geli; hide

    2016-01-01

    Accurate estimation of the gross primary production (GPP) of terrestrial ecosystems is vital for a better understanding of the spatial-temporal patterns of the global carbon cycle. In this study,we estimate GPP in North America (NA) using the satellite-based Vegetation Photosynthesis Model (VPM), MODIS (Moderate Resolution Imaging Spectrometer) images at 8-day temporal and 500 meter spatial resolutions, and NCEP-NARR (National Center for Environmental Prediction-North America Regional Reanalysis) climate data. The simulated GPP (GPP (sub VPM)) agrees well with the flux tower derived GPP (GPPEC) at 39 AmeriFlux sites (155 site-years). The GPP (sub VPM) in 2010 is spatially aggregated to 0.5 by 0.5-degree grid cells and then compared with sun-induced chlorophyll fluorescence (SIF) data from Global Ozone Monitoring Instrument 2 (GOME-2), which is directly related to vegetation photosynthesis. Spatial distribution and seasonal dynamics of GPP (sub VPM) and GOME-2 SIF show good consistency. At the biome scale, GPP (sub VPM) and SIF shows strong linear relationships (R (sup 2) is greater than 0.95) and small variations in regression slopes ((4.60-5.55 grams Carbon per square meter per day) divided by (milliwatts per square meter per nanometer per square radian)). The total annual GPP (sub VPM) in NA in 2010 is approximately 13.53 petagrams Carbon per year, which accounts for approximately 11.0 percent of the global terrestrial GPP and is within the range of annual GPP estimates from six other process-based and data-driven models (11.35-22.23 petagrams Carbon per year). Among the seven models, some models did not capture the spatial pattern of GOME-2 SIF data at annual scale, especially in Midwest cropland region. The results from this study demonstrate the reliable performance of VPM at the continental scale, and the potential of SIF data being used as a benchmark to compare with GPP models.

  7. Role of the PufX protein in photosynthetic growth of Rhodobacter sphaeroides. 2. PufX is required for efficient ubiquinone/ubiquinol exchange between the reaction center QB site and the cytochrome bc1 complex.

    Science.gov (United States)

    Barz, W P; Verméglio, A; Francia, F; Venturoli, G; Melandri, B A; Oesterhelt, D

    1995-11-21

    The PufX membrane protein is essential for photosynthetic growth of Rhodobacter sphaeroides because it is required for multiple-turnover electron transfer under anaerobic conditions [see accompanying article; Barz, W. P., Francia, F., Venturoli, G., Melandri, B. A., Verméglio, A., & Oesterhelt, D. (1995) Biochemistry 34, 15235-15247]. In order to understand the molecular role of PufX, light-induced absorption spectroscopy was performed using a pufX- mutant, a pufX+ strain, and two suppressor mutants. We show that the reaction center (RC) requires PufX for its functionality under different redox conditions than the cytochrome bc1 complex: When the kinetics of flash-induced reduction of cytochrome b561 were monitored in chromatophores, we observed a requirement of PufX for turnover of the cytochrome bc1 complex only at high redox potential (Eh > 140 mV), suggesting a function of PufX in lateral ubiquinol transfer from the RC. In contrast, PufX is required for multiple turnover of the RC only under reducing conditions: When the Q pool was partially oxidized in vivo using oxygen or electron acceptors like dimethyl sulfoxide or trimethylamine N-oxide, the deletion of PufX had no effect on light-driven electron flow through the RC. Flash train experiments under anaerobic in vivo conditions revealed that RC photochemistry does not depend on PufX for the first two flash excitations. Following the third and subsequent flashes, however, efficient charge separation requires PufX, indicating an important role of PufX for fast Q/QH2 exchange at the QB site of the RC. We show that the Q/QH2 exchange rate is reduced approximately 500-fold by the deletion of PufX when the Q pool is nearly completely reduced, demonstrating an essential role of PufX for the access of ubiquinone to the QB site. The fast ubiquinone/ubiquinol exchange is partially restored by suppressor mutations altering the macromolecular antenna structure. These results suggest an indirect role of PufX in

  8. The unusually strong hydrogen bond between the carbonyl of Q(A) and His M219 in the Rhodobacter sphaeroides reaction center is not essential for efficient electron transfer from Q(A)(-) to Q(B).

    Science.gov (United States)

    Breton, Jacques; Lavergne, Jérôme; Wakeham, Marion C; Nabedryk, Eliane; Jones, Michael R

    2007-06-05

    In native reaction centers (RCs) from photosynthetic purple bacteria the primary quinone (QA) and the secondary quinone (QB) are interconnected via a specific His-Fe-His bridge. In Rhodobacter sphaeroides RCs the C4=O carbonyl of QA forms a very strong hydrogen bond with the protonated Npi of His M219, and the Ntau of this residue is in turn coordinated to the non-heme iron atom. The second carbonyl of QA is engaged in a much weaker hydrogen bond with the backbone N-H of Ala M260. In previous work, a Trp side chain was introduced by site-directed mutagenesis at the M260 position in the RC of Rb. sphaeroides, resulting in a complex that is completely devoid of QA and therefore nonfunctional. A photochemically competent derivative of the AM260W mutant was isolated that contains a Cys side chain at the M260 position (denoted AM260(W-->C)). In the present work, the interactions between the carbonyl groups of QA and the protein in the AM260(W-->C) suppressor mutant have been characterized by light-induced FTIR difference spectroscopy of the photoreduction of QA. The QA-/QA difference spectrum demonstrates that the strong interaction between the C4=O carbonyl of QA and His M219 is lost in the mutant, and the coupled CO and CC modes of the QA- semiquinone are also strongly perturbed. In parallel, a band assigned to the perturbation of the C5-Ntau mode of His M219 upon QA- formation in the native RC is lacking in the spectrum of the mutant. Furthermore, a positive band between 2900 and 2400 cm-1 that is related to protons fluctuating within a network of highly polarizable hydrogen bonds in the native RC is reduced in amplitude in the mutant. On the other hand, the QB-/QB FTIR difference spectrum is essentially the same as for the native RC. The kinetics of electron transfer from QA- to QB were measured by the flash-induced absorption changes at 780 nm. Compared to native RCs the absorption transients are slowed by a factor of about 2 for both the slow phase (in the

  9. Mutation of Gly195 of the ChlH subunit of Mg-chelatase reduces chlorophyll and further disrupts PS II assembly in a Ycf48-deficient strain of Synechocystis sp. PCC 6803

    Directory of Open Access Journals (Sweden)

    Tim Crawford

    2016-07-01

    Full Text Available Biogenesis of the photosystems in oxygenic phototrophs requires co-translational insertion of chlorophyll a. The first committed step of chlorophyll a biosynthesis is the insertion of a Mg2+ ion into the tetrapyrrole intermediate protoporphyrin IX, catalyzed by Mg-chelatase. We have identified a Synechocystis sp. PCC 6803 strain with a spontaneous mutation in chlH that results in a Gly195 to Glu substitution in a conserved region of the catalytic subunit of Mg-chelatase. Mutant strains containing the ChlH Gly195 to Glu mutation were generated using a two-step protocol that introduced the chlH gene into a putative neutral site in the chromosome prior to deletion of the native gene. The Gly195 to Glu mutation resulted in strains with decreased chlorophyll a. Deletion of the PS II assembly factor Ycf48 in a strain carrying the ChlH Gly195 to Glu mutation did not grow photoautotrophically. In addition, the ChlH-G195E:ΔYcf48 strain showed impaired PS II activity and decreased assembly of PS II centers in comparison to a ΔYcf48 strain. We suggest decreased chlorophyll in the ChlH-G195E mutant provides a background to screen for the role of assembly factors that are not essential under optimal growth conditions.

  10. Measuring solar induced chlorophyll fluorescence (SIF) in the Amazon rainforest

    Science.gov (United States)

    Kornfeld, A.; Stutz, J.; Berry, J. A.

    2016-12-01

    Measurement of solar induced chlorophyll fluorescence (SIF) has, in our hands, been fraught with missteps and puzzling problems. Here we describe lessons we have learned and the resulting novel system recently installed in the Amazon rainforest near Manaus, Brazil. The system is designed to measure light from 740 - 780 nm, enabling us to compare SIF computed from Fraunhofer lines in an optically transparent band of the atmosphere (745 - 759 nm) with SIF computed using the telluric O2A band (760 - 770 nm). Fraunhofer line analysis requires high optical resolution (better than 0.2 nm) to detect the relatively narrow lines, but we discovered that fiber-optic diffraction-grating spectrometers are sensitive to very small inhomogeneities in the lighting. Errors resulting from this autocorrelated but random noise were similar in magnitude to the SIF signal itself. Optical diffusers reduce this problem, leading to our final design: a sealed cylinder, dubbed Rotaprism, in which a rotatable prism selects whether light from upward- or downward-looking windows enters an axially-placed optical fiber. Cosine-correcting opal glass covering the windows not only solves the noise issue but also makes the measurements correspond to photon flux. Rotaprism also maximizes the amount of light reaching the spectrometer - maximizing the signal:noise ratio - by avoiding the need for lossy optical switches and fiber splitters. Rotaprism is driven by a pneumatic actuator that is controlled by electronic valves attached to a pressurized N2 source. The gas exhausts into the temperature-controlled spectrometer enclosure to help purge the optics. Finally, custom software provides fault-tolerant control and data acquisition, ensuring that measurements continue with little or no intervention at the remote field site despite unreliable power. Analysis of initial data demonstrates the advantage of Fraunhofer line SIF analysis: due to the atmosphere transparency in this band, the results are more

  11. Chlorophyll fluorescence response to water and nitrogen deficit

    Science.gov (United States)

    Cendrero Mateo, Maria del Pilar

    The increasing food demand as well as the need to predict the impact of warming climate on vegetation makes it critical to find the best tools to assess crop production and carbon dioxide (CO2) exchange between the land and atmosphere. Photosynthesis is a good indicator of crop production and CO2 exchange. Chlorophyll fluorescence (ChF) is directly related to photosynthesis. ChF can be measured at leaf-scale using active techniques and at field-scales using passive techniques. The measurement principles of both techniques are different. In this study, three overarching questions about ChF were addressed: Q1) How water, nutrient and ambient light conditions determine the relationships between photosynthesis and ChF? Which is the optimum irradiance level for detecting water and nutrient deficit conditions with ChF? ; Q2) which are the limits within which active and passive techniques are comparable?; and Q3) What is the seasonal relationship between photosynthesis and ChF when nitrogen is the limiting factor? To address these questions, two main experiments were conducted: Exp1) Concurrent photosynthesis and ChF light-response curves were measured in camelina and wheat plants growing under (i) intermediate-light and (ii) high-light conditions respectively. Plant stress was induced by (i) withdrawing water, and (ii) applying different nitrogen levels; and Exp2) coincident active and passive ChF measurements were made in a wheat field under different nitrogen treatments. The results indicated ChF has a direct relationship with photosynthesis when water or nitrogen drives the relationship. This study demonstrates that the light level at which plants were grown was optimum for detecting water and nutrient deficit with ChF. Also, the results showed that for leaf-average-values, active measurements can be used to better understand the daily and seasonal behavior of passive ChF. Further, the seasonal relation between photosynthesis and ChF with nitrogen stress was not a

  12. Overview of Global Monitoring of Terrestrial Chlorophyll Fluorescence from Space

    Science.gov (United States)

    Guanter, Luis; Zhang, Yongguang; Kohler, Philipp; Walther, Sophia; Frankenberg, Christian; Joiner, Joanna

    2016-01-01

    Despite the critical importance of photosynthesis for the Earth system, understanding how it is influenced by factors such as climate variability, disturbance history, and water or nutrient availability remains a challenge because of the complex interactions and the lack of GPP measurements at various temporal and spatial scales. Space observations of the sun-induced chlorophyll fluorescence (SIF) electromagnetic signal emitted by plants in the 650-850nm spectral range hold the promise of providing a new view of vegetation photosynthesis on a global basis. Global retrievals of SIF from space have recently been achieved from a number of spaceborne spectrometers originally intended for atmospheric research. Despite not having been designed for land applications, such instruments have turned out to provide the necessary spectral and radiometric sensitivity for SIF retrieval from space. The first global measurements of SIF were achieved in 2011 from spectra acquired by the Japanese GOSAT mission launched in 2009. The retrieval takes advantage of the high spectral resolution provided by GOSATs Fourier Transform Spectrometer (FTS) which allows the evaluation of the in-filling of solar Fraunhofer lines by SIF. Unfortunately, GOSAT only provides a sparse spatial sampling with individual soundings separated by several hundred kilometers. Complementary, the Global Ozone Monitoring Experiment-2 (GOME-2) instruments onboard MetOp-A and MetOp-B enable SIF retrievals since 2007 with a continuous and global spatial coverage. GOME-2 measures in the red and near-infrared (NIR) spectral regions with a spectral resolution of 0.5 nm and a pixel size of up to 40x40 km2. Most recently, another global and spatially continuous data set of SIF retrievals at 740 nm spanning the 2003-2012 time frame has been produced from ENVISATSCIAMACHY. This observational scenario has been completed by the first fluorescence data from the NASA-JPL OCO-2 mission (launched in July 2014) and the upcoming

  13. Chlorophyll-a retrieval in the Philippine waters

    Science.gov (United States)

    Perez, G. J. P.; Leonardo, E. M.; Felix, M. J.

    2017-12-01

    Satellite-based monitoring of chlorophyll-a (Chl-a) concentration has been widely used for estimating plankton biomass, detecting harmful algal blooms, predicting pelagic fish abundance, and water quality assessment. Chl-a concentrations at 1 km spatial resolution can be retrieved from MODIS onboard Aqua and Terra satellites. However, with this resolution, MODIS has scarce Chl-a retrieval in coastal and inland waters, which are relevant for archipelagic countries such as the Philippines. These gaps on Chl-a retrieval can be filled by sensors with higher spatial resolution, such as the OLI of Landsat 8. In this study, assessment of Chl-a concentration derived from MODIS/Aqua and OLI/Landsat 8 imageries across the open, coastal and inland waters of the Philippines was done. Validation activities were conducted at eight different sites around the Philippines for the period October 2016 to April 2017. Water samples filtered on the field were processed in the laboratory for Chl-a extraction. In situ remote sensing reflectance was derived from radiometric measurements and ancillary information, such as bathymetry and turbidity, were also measured. Correlation between in situ and satellite-derived Chl-a concentration using the blue-green ratio yielded relatively high R2 values of 0.51 to 0.90. This is despite an observed overestimation for both MODIS and OLI-derived values, especially in turbid and coastal waters. The overestimation of Chl-a may be attributed to inaccuracies in i) remote sensing reflectance (Rrs) retrieval and/or ii) empirical model used in calculating Chl-a concentration. However, a good 1:1 correspondence between the satellite and in situ maximum Rrs band ratio was established. This implies that the overestimation is largely due to the inaccuracies from the default coefficients used in the empirical model. New coefficients were then derived from the correlation analysis of both in situ-measured Chl-a concentration and maximum Rrs band ratio. This

  14. Long-term dynamics of chlorophyll concentration in the ocean surface layer (by space data)

    Science.gov (United States)

    Shevyrnogov, A.; Vysotskaya, G.

    To preserve the biosphere and to use it efficiently, it is necessary to gain a deep insight into the dynamics of the primary production process on our planet. Variability of chlorophyll concentration in the ocean is one of the most important components of this process. These investigations are, however, very labor-consuming, because of the difficulties related to the accessibility of the water surface and its large size. In this work long-term changes in chlorophyll concentration in the surface layer of the ocean have been analyzed on the basis of the CZCS data for 7.5 years from 1979 to 1986 and the SeaWiFS data from 1997 to 2004. It has been shown that the average chlorophyll concentration calculated in all investigated areas varies moderately. However, when analyzing spatially local trends, the areas have been detected that have significant rise and fall of chlorophyll concentrations. Some interesting features of the long-term dynamics of chlorophyll concentration have been found. The opposite directions of long-term trends (essential increase or decrease) cannot be explained only by large-scale hydrological phenomena in the ocean (currents, upwellings, etc.). The measured chlorophyll concentration results from the balance between production and destruction processes. Which process dominates is determined by various hydrophysical, hydrobiological, and climatic processes, leading to sharp rises or falls of the concentration. It is important to estimate the scale of the areas in which this or that process dominates. Therefore, the study addresses not only the dynamics of the mean value but also the dynamics of the areas in which the dominance of certain factors has led to a sharp fall or rise in chlorophyll concentration. Thus, the obtained results can be used to estimate long-term changes in the ocean biota.

  15. How is the chlorophyll count affected by burned and unburned marsh areas?

    Science.gov (United States)

    Kendrick, C.

    2017-12-01

    Does marsh burnings, either man made or natural, hinder or help Louisiana's vitally important coastal plant life? Does the carbon produced from the fires have a negative effect on the chlorophyll count of these precious living protective barriers? Or does it help contribute to raising the plants chlorophyll count? Along Louisiana's Gulf Coast, marsh burnings are conducted every 2-4 years to destroy some of the Spartina patens. Fires and smoke may have an effect on the chlorophyll count of the plants found in Louisiana's marshes. Peat burns, root burns, and cover burns are the three types of marsh fires. These burns can be either man made or started by natural causes. Peat burns occur when the soil is dry due to a drained marsh. Root burns occur when plant roots are burned without the soil being consumed. Cover burns occur when several centimeters of water covers the soil. Cover burns are often used by Wildlife and Fisheries personnel to promote preferred plant food growth like Scirpus olneyi rather than the dominant Spartina patens. Our project was conducted by testing marsh plants and obtaining chlorophyll count of both a burned (cover burn) and an unburned area. Approximately one year after the burn, in August 2015, we tested the burned area's site. We retested the same site in December 2016. The results from our testing showed that there was a slightly higher chlorophyll count in the burned area. The chlorophyll count average from the two testing days was 33.5 in the burned area and 30.15 in the unburned area. Our hypothesis was that the chlorophyll content of "controlled" burned wetland areas will have a higher amount than the "no" burn area. The experiment results supported this hypothesis by showing an increase of 3.35 average in the burned area.

  16. A study of the low-lying singlet and triplet electronic states of chlorophyll A and B

    Directory of Open Access Journals (Sweden)

    Etinski Mihajlo

    2013-01-01

    Full Text Available Chlorophylls have been extensively investigated both experimentally and theoretically owing to the fact that they are essential for photosynthesis. We have studied two forms of chlorophyll, chlorophyll a and chlorophyll b, by means of density functional theory. Optimization of S0, S1 and T1 states was performed with the B3-LYP functional. The computed fluorescence lifetimes show good agreement with the available experimental data. The electronic adiabatic energies of S1 and T1 states are 2.09/2.12 and 1.19/1.29 eV for chlorophyll a and chlorophyll b respectively. We discussed the implications of this results on the triplet formation. Also, the calculated vertical ionization potentials shows good agreement with the experimental results. [Projekat Ministarstva nauke Reoublike Srbije, br. 172040

  17. The effect of High Pressure and High Temperature processing on carotenoids and chlorophylls content in some vegetables.

    Science.gov (United States)

    Sánchez, Celia; Baranda, Ana Beatriz; Martínez de Marañón, Iñigo

    2014-11-15

    The effect of High Pressure (HP) and High Pressure High Temperature (HPHT) processing on carotenoid and chlorophyll content of six vegetables was evaluated. In general, carotenoid content was not significantly influenced by HP or HPHT treatments (625 MPa; 5 min; 20, 70 and 117 °C). Regarding chlorophylls, HP treatment caused no degradation or slight increases, while HPHT processes degraded both chlorophylls. Chlorophyll b was more stable than chlorophyll a at 70 °C, but both of them were highly degraded at 117 °C. HPHT treatment at 117 °C provided products with a good retention of carotenoids and colour in the case of red vegetables. Even though the carotenoids also remained in the green vegetables, their chlorophylls and therefore their colour were so affected that milder temperatures need to be applied. As an industrial scale equipment was used, results will be useful for future industrial implementation of this technology. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. Direct Reactions

    Energy Technology Data Exchange (ETDEWEB)

    Austern, N. [University of Pittsburgh, Pittsburgh, PA (United States)

    1963-01-15

    In order to give a unified presentation of one point of view, these lectures are devoted only to a detailed development of the standard theories of direct reactions, starting from basic principles. Discussion is given of the present status of the theories, of the techniques used for practical calculation, and of possible future developments. The direct interaction (DI) aspects of a reaction are those which involve only a few of the many degrees of freedom of a nucleus. In fact the minimum number of degrees of freedom which must be involved in a reaction are those required to describe the initial and final channels, and DI studies typically consider these degrees of freedom and no others. Because of this simplicity DI theories may be worked out in painstaking detail. DI processes concern only part of the wave function for a problem. The other part involves complicated excitations of many degrees of freedom, and gives the compound nucleus (CN) effects. While it is extremely interesting to learn how to separate DI and CN effects in an orderly manner, if they are both present in a reaction, no suitable method has yet been found. Instead, current work stresses the kinds of reactions and the kinds of final states in which DI effects dominate and in which CN effects may almost be forgotten. The DI cross-sections which are studied are often extremely large, comparable to elastic scattering cross-sections. (author)

  19. Indian Ocean Dipole and El Niño/Southern Oscillation impacts on regional chlorophyll anomalies in the Indian Ocean

    Directory of Open Access Journals (Sweden)

    J. C. Currie

    2013-10-01

    Full Text Available The Indian Ocean Dipole (IOD and the El Niño/Southern Oscillation (ENSO are independent climate modes, which frequently co-occur, driving significant interannual changes within the Indian Ocean. We use a four-decade hindcast from a coupled biophysical ocean general circulation model, to disentangle patterns of chlorophyll anomalies driven by these two climate modes. Comparisons with remotely sensed records show that the simulation competently reproduces the chlorophyll seasonal cycle, as well as open-ocean anomalies during the 1997/1998 ENSO and IOD event. Results suggest that anomalous surface and euphotic-layer chlorophyll blooms in the eastern equatorial Indian Ocean in fall, and southern Bay of Bengal in winter, are primarily related to IOD forcing. A negative influence of IOD on chlorophyll concentrations is shown in a region around the southern tip of India in fall. IOD also depresses depth-integrated chlorophyll in the 5–10° S thermocline ridge region, yet the signal is negligible in surface chlorophyll. The only investigated region where ENSO has a greater influence on chlorophyll than does IOD, is in the Somalia upwelling region, where it causes a decrease in fall and winter chlorophyll by reducing local upwelling winds. Yet unlike most other regions examined, the combined explanatory power of IOD and ENSO in predicting depth-integrated chlorophyll anomalies is relatively low in this region, suggestive that other drivers are important there. We show that the chlorophyll impact of climate indices is frequently asymmetric, with a general tendency for larger positive than negative chlorophyll anomalies. Our results suggest that ENSO and IOD cause significant and predictable regional re-organisation of chlorophyll via their influence on near-surface oceanography. Resolving the details of these effects should improve our understanding, and eventually gain predictability, of interannual changes in Indian Ocean productivity, fisheries

  20. Thermocline Regulated Seasonal Evolution of Surface Chlorophyll in the Gulf of Aden

    KAUST Repository

    Yao, Fengchao

    2015-03-19

    The Gulf of Aden, although subject to seasonally reversing monsoonal winds, has been previously reported as an oligotrophic basin during summer, with elevated chlorophyll concentrations only occurring during winter due to convective mixing. However, the Sea-Viewing Wide Field-of-View Sensor (SeaWiFS) ocean color data reveal that the Gulf of Aden also exhibits a prominent summer chlorophyll bloom and sustains elevated chlorophyll concentrations throughout the fall, and is a biophysical province distinct from the adjacent Arabian Sea. Climatological hydrographic data suggest that the thermocline, hence the nutricline, in the entire gulf is markedly shoaled by the southwest monsoon during summer and fall. Under this condition, cyclonic eddies in the gulf can effectively pump deep nutrients to the surface layer and lead to the chlorophyll bloom in late summer, and, after the transition to the northeast monsoon in fall, coastal upwelling driven by the northeasterly winds produces a pronounced increase in surface chlorophyll concentrations along the Somali coast. © 2015 Yao, Hoteit.

  1. Expanded separation technique for chlorophyll metabolites in Oriental tobacco leaf using non aqueous reversed phase chromatography.

    Science.gov (United States)

    Ishida, Naoyuki

    2011-08-26

    An improved separation method for chlorophyll metabolites in Oriental tobacco leaf was developed. While Oriental leaf still gives the green color even after the curing process, little attention has been paid to the detailed composition of the remaining green pigments. This study aimed to identify the green pigments using non aqueous reversed phase chromatography (NARPC). To this end, liquid chromatograph (LC) equipped with a photo diode array detector (DAD) and an atmospheric pressure chemical ionization/mass spectrometer (APCI/MSD) was selected, because it is useful for detecting low polar non-volatile compounds giving green color such as pheophytin a. Identification was based on the wavelength spectrum, mass spectrum and retention time, comparing the analytes in Oriental leaf with the commercially available and synthesized components. Consequently, several chlorophyll metabolites such as hydroxypheophytin a, solanesyl pheophorbide a and solanesyl hydroxypheophorbide a were newly identified, in addition to typical green pigments such as chlorophyll a and pheophytin a. Chlorophyll metabolites bound to solanesol were considered the tobacco specific components. NARPC expanded the number of detectable low polar chlorophyll metabolites in Oriental tobacco leaf. Copyright © 2011 Elsevier B.V. All rights reserved.

  2. Culture of a high-chlorophyll-producing and halotolerant Chlorella vulgaris.

    Science.gov (United States)

    Nakanishi, Koichi; Deuchi, Keiji

    2014-05-01

    In order to increase the value of freshwater algae as raw ingredients for health foods and feed for seawater-based farmed fish, we sought to breed high-chlorophyll halotolerant Chlorella with the objective of generating strains with both high chlorophyll concentrations (≥ 5%) and halotolerance (up to 1% NaCl). We used the Chlorella vulgaris K strain in our research institute culture collection and induced mutations with UV irradiation and acriflavine which is known to effect mutations of mitochondrial DNA that are associated with chlorophyll production. Screenings were conducted on seawater-based "For Chlorella spp." (FC) agar medium, and dark-green-colored colonies were visually selected by macroscopic inspection. We obtained a high-chlorophyll halotolerant strain (designated C. vulgaris M-207A7) that had a chlorophyll concentration of 6.7% (d.m.), a level at least three-fold higher than that of K strain. This isolate also exhibited a greater survival rate in seawater that of K strain. Copyright © 2013 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  3. Leaf Chlorophyll Content Estimation of Winter Wheat Based on Visible and Near-Infrared Sensors.

    Science.gov (United States)

    Zhang, Jianfeng; Han, Wenting; Huang, Lvwen; Zhang, Zhiyong; Ma, Yimian; Hu, Yamin

    2016-03-25

    The leaf chlorophyll content is one of the most important factors for the growth of winter wheat. Visual and near-infrared sensors are a quick and non-destructive testing technology for the estimation of crop leaf chlorophyll content. In this paper, a new approach is developed for leaf chlorophyll content estimation of winter wheat based on visible and near-infrared sensors. First, the sliding window smoothing (SWS) was integrated with the multiplicative scatter correction (MSC) or the standard normal variable transformation (SNV) to preprocess the reflectance spectra images of wheat leaves. Then, a model for the relationship between the leaf relative chlorophyll content and the reflectance spectra was developed using the partial least squares (PLS) and the back propagation neural network. A total of 300 samples from areas surrounding Yangling, China, were used for the experimental studies. The samples of visible and near-infrared spectroscopy at the wavelength of 450,900 nm were preprocessed using SWS, MSC and SNV. The experimental results indicate that the preprocessing using SWS and SNV and then modeling using PLS can achieve the most accurate estimation, with the correlation coefficient at 0.8492 and the root mean square error at 1.7216. Thus, the proposed approach can be widely used for winter wheat chlorophyll content analysis.

  4. Chlorophyll fluorescence lifetime imaging provides new insight into the chlorosis induced by plant virus infection.

    Science.gov (United States)

    Lei, Rong; Jiang, Hongshan; Hu, Fan; Yan, Jin; Zhu, Shuifang

    2017-02-01

    Leaf chlorosis induced by plant virus infection has a short fluorescence lifetime, which reflects damaged photosynthetic complexes and degraded chloroplasts. Plant viruses often induce chlorosis and necrosis, which are intimately related to photosynthetic functions. Chlorophyll fluorescence lifetime measurement is a valuable noninvasive tool for analyzing photosynthetic processes and is a sensitive indicator of the environment surrounding the fluorescent molecules. In this study, our central goal was to explore the effect of viral infection on photosynthesis by employing chlorophyll fluorescence lifetime imaging (FLIM), steady-state fluorescence, non-photochemical quenching (NPQ), transmission electron microscopy (TEM), and pigment analysis. The data indicated that the chlorophyll fluorescence lifetime of chlorotic leaves was significantly shorter than that of healthy control leaves, and the fitted short lifetime component of chlorophyll fluorescence of chlorotic leaves was dominant. This dominant short lifetime component may result from damage to the structure of thylakoid, which was confirmed by TEM. The NPQ value of chlorotic leaves was slightly higher than that of healthy green leaves, which can be explained by increased neoxanthin, lutein and violaxanthin content relative to chlorophyll a. The difference in NPQ is slight, but FLIM can provide simple and direct characterization of PSII structure and photosynthetic function. Therefore, this technique shows great potential as a simple and rapid method for studying mechanisms of plant virus infection.

  5. Arabidopsis chlorophyll biosynthesis: an essential balance between the methylerythritol phosphate and tetrapyrrole pathways.

    Science.gov (United States)

    Kim, Se; Schlicke, Hagen; Van Ree, Kalie; Karvonen, Kristine; Subramaniam, Anant; Richter, Andreas; Grimm, Bernhard; Braam, Janet

    2013-12-01

    Chlorophyll, essential for photosynthesis, is composed of a chlorin ring and a geranylgeranyl diphosphate (GGPP)-derived isoprenoid, which are generated by the tetrapyrrole and methylerythritol phosphate (MEP) biosynthesis pathways, respectively. Although a functional MEP pathway is essential for plant viability, the underlying basis of the requirement has been unclear. We hypothesized that MEP pathway inhibition is lethal because a reduction in GGPP availability results in a stoichiometric imbalance in tetrapyrrolic chlorophyll precursors, which can cause deadly photooxidative stress. Consistent with this hypothesis, lethality of MEP pathway inhibition in Arabidopsis thaliana by fosmidomycin (FSM) is light dependent, and toxicity of MEP pathway inhibition is reduced by genetic and chemical impairment of the tetrapyrrole pathway. In addition, FSM treatment causes a transient accumulation of chlorophyllide and transcripts associated with singlet oxygen-induced stress. Furthermore, exogenous provision of the phytol molecule reduces FSM toxicity when the phytol can be modified for chlorophyll incorporation. These data provide an explanation for FSM toxicity and thereby provide enhanced understanding of the mechanisms of FSM resistance. This insight into MEP pathway inhibition consequences underlines the risk plants undertake to synthesize chlorophyll and suggests the existence of regulation, possibly involving chloroplast-to-nucleus retrograde signaling, that may monitor and maintain balance of chlorophyll precursor synthesis.

  6. Relationships between nutrients and chlorophyll a concentration in the international Alma Gol Wetland, Iran

    Directory of Open Access Journals (Sweden)

    Saeed Balali

    2013-05-01

    Full Text Available This study investigated the relationships between nutrients and chlorophyll, a concentration in the International Alma Gol Wetland. Chlorophyll a is the major photosynthetic pigment in lots of phytoplanktons and has been used as a trophy index in aquatic ecosystems. Water samples were collected fortnightly from five stations in the wetland during summer and autumn. Chlorophyll-a ranged between 4.38 to 156.55 mg/m3, sulfate ranged between 138 to 190 mg/l, total alkalinity ranged between 80 to 280 mg/l, silica ranged between 3.80 to 35.00 mg/l, phosphate ranged between 0.02 to 3.70 mg/l, ammonia ranged between 0.10 to 11.90 mg/l, nitrate ranged between 0.01 to 2.75 mg/l and nitrite ranged between 0.01 to 0.39 mg/l. There was a significant correlation between chlorophyll a and nitrate, nitrite and ammonia but there was no significant correlation between chlorophyll a and silica, total alkalinity, sulfate and phosphorus.

  7. Coherence and population dynamics of chlorophyll excitations in FCP complex: Two-dimensional spectroscopy study

    Energy Technology Data Exchange (ETDEWEB)

    Butkus, Vytautas; Gelzinis, Andrius; Valkunas, Leonas [Department of Theoretical Physics, Faculty of Physics, Vilnius University, Sauletekio Ave. 9-III, 10222 Vilnius (Lithuania); Center for Physical Sciences and Technology, Savanoriu Ave. 231, 02300 Vilnius (Lithuania); Augulis, Ramūnas [Center for Physical Sciences and Technology, Savanoriu Ave. 231, 02300 Vilnius (Lithuania); Gall, Andrew; Robert, Bruno [Institut de Biologie et Technologies de Saclay, Bât 532, Commissariat à l’Energie Atomique Saclay, 91191 Gif sur Yvette (France); Büchel, Claudia [Institut für Molekulare Biowissenschaften, Universität Frankfurt, Max-von-Laue-Straße 9, Frankfurt (Germany); Zigmantas, Donatas [Department of Chemical Physics, Lund University, P.O. Box 124, 22100 Lund (Sweden); Abramavicius, Darius, E-mail: darius.abramavicius@ff.vu.lt [Department of Theoretical Physics, Faculty of Physics, Vilnius University, Sauletekio Ave. 9-III, 10222 Vilnius (Lithuania)

    2015-06-07

    Energy transfer processes and coherent phenomena in the fucoxanthin–chlorophyll protein complex, which is responsible for the light harvesting function in marine algae diatoms, were investigated at 77 K by using two-dimensional electronic spectroscopy. Experiments performed on femtosecond and picosecond timescales led to separation of spectral dynamics, witnessing evolutions of coherence and population states of the system in the spectral region of Q{sub y} transitions of chlorophylls a and c. Analysis of the coherence dynamics allowed us to identify chlorophyll (Chl) a and fucoxanthin intramolecular vibrations dominating over the first few picoseconds. Closer inspection of the spectral region of the Q{sub y} transition of Chl c revealed previously not identified, mutually non-interacting chlorophyll c states participating in femtosecond or picosecond energy transfer to the Chl a molecules. Consideration of separated coherent and incoherent dynamics allowed us to hypothesize the vibrations-assisted coherent energy transfer between Chl c and Chl a and the overall spatial arrangement of chlorophyll molecules.

  8. Using visible reflectance spectroscopy to reconstruct historical changes in chlorophyll a concentration in East Antarctic ponds

    Directory of Open Access Journals (Sweden)

    Qianqian Chen

    2013-12-01

    Full Text Available The visible reflectance spectroscopy (VRS and chlorophyll a concentration were determined in three sediment profiles collected from East Antarctica to investigate the potential application of VRS in reconstructing historical changes in Antarctic lake primary productivity. The results showed that the appearance of a trough at 650–700 nm is an important marker for chlorophyll a concentration and can therefore be used to distinguish the sedimentary organic matter source from guano and algae. The measured chlorophyll a content had significant positive correlations with the trough area between 650 and 700 nm, and no distinct trough was found in the sediments with organic matter completely derived from guano. Modelling results showed that the spectra spectrally inferred chlorophyll a content, and the measured data exhibit consistent trends with depth, showing that the dimensionless trough area can serve as an independent proxy for reconstructing historical fluctuations in the primary production of Antarctic ponds. The correlation of phosphorus (P with measured and inferred chlorophyll a contents in ornithogenic sediments near penguin colonies indicates that the change in primary productivity in the Antarctic ponds investigated was closely related to the amount of guano input from these birds.

  9. Why is the Ratio of Reflectivity Effective for Chlorophyll Estimation in the Lake Water?

    Directory of Open Access Journals (Sweden)

    Kazuo Oki

    2010-07-01

    Full Text Available The reasons why it is effective to estimate the chlorophyll-a concentration with the ratio of spectral radiance reflectance at the red light region and near infrared regions were shown in theory using a two-flow model. It was found that all of the backscattering coefficients can consequently be ignored by using the ratio of spectral radiance reflectance, which is the ratio of the upward radiance to the downward irradiance, at the red light and near infrared regions. In other words, the ratio can be expressed by using only absorption coefficients, which are more stable for measurement than backscattering coefficients. In addition, the band selection is crucial for producing the band ratio when the chlorophyll-a concentration is estimated without the effects of backscattering. I conclude that the two wavelengths selected must be close, but one must be within the absorption range of chlorophyll-a, and the other must be outside of the absorption range of chlorophyll-a, in order to accurately estimate the chlorophyll-a concentration.

  10. Impact of chlorophyll bias on the tropical Pacific mean climate in an earth system model

    Science.gov (United States)

    Lim, Hyung-Gyu; Park, Jong-Yeon; Kug, Jong-Seong

    2017-12-01

    Climate modeling groups nowadays develop earth system models (ESMs) by incorporating biogeochemical processes in their climate models. The ESMs, however, often show substantial bias in simulated marine biogeochemistry which can potentially introduce an undesirable bias in physical ocean fields through biogeophysical interactions. This study examines how and how much the chlorophyll bias in a state-of-the-art ESM affects the mean and seasonal cycle of tropical Pacific sea-surface temperature (SST). The ESM used in the present study shows a sizeable positive bias in the simulated tropical chlorophyll. We found that the correction of the chlorophyll bias can reduce the ESM's intrinsic cold SST mean bias in the equatorial Pacific. The biologically-induced cold SST bias is strongly affected by seasonally-dependent air-sea coupling strength. In addition, the correction of chlorophyll bias can improve the annual cycle of SST by up to 25%. This result suggests a possible modeling approach in understanding the two-way interactions between physical and chlorophyll biases by biogeophysical effects.

  11. Principal Component Analysis of Chlorophyll Content in Tobacco, Bean and Petunia Plants Exposed to Different Tropospheric Ozone Concentrations

    Science.gov (United States)

    Borowiak, Klaudia; Zbierska, Janina; Budka, Anna; Kayzer, Dariusz

    2014-06-01

    Three plant species were assessed in this study - ozone-sensitive and -resistant tobacco, ozone-sensitive petunia and bean. Plants were exposed to ambient air conditions for several weeks in two sites differing in tropospheric ozone concentrations in the growing season of 2009. Every week chlorophyll contents were analysed. Cumulative ozone effects on the chlorophyll content in relation to other meteorological parameters were evaluated using principal component analysis, while the relation between certain days of measurements of the plants were analysed using multivariate analysis of variance. Results revealed variability between plant species response. However, some similarities were noted. Positive relations of all chlorophyll forms to cumulative ozone concentration (AOT 40) were found for all the plant species that were examined. The chlorophyll b/a ratio revealed an opposite position to ozone concentration only in the ozone-resistant tobacco cultivar. In all the plant species the highest average chlorophyll content was noted after the 7th day of the experiment. Afterwards, the plants usually revealed various responses. Ozone-sensitive tobacco revealed decrease of chlorophyll content, and after few weeks of decline again an increase was observed. Probably, due to the accommodation for the stress factor. While during first three weeks relatively high levels of chlorophyll contents were noted in ozone-resistant tobacco. Petunia revealed a slow decrease of chlorophyll content and the lowest values at the end of the experiment. A comparison between the plant species revealed the highest level of chlorophyll contents in ozone-resistant tobacco.

  12. Reaction mechanisms

    International Nuclear Information System (INIS)

    Nguyen Trong Anh

    1988-01-01

    The 1988 progress report of the Reaction Mechanisms laboratory (Polytechnic School, France), is presented. The research topics are: the valence bond methods, the radical chemistry, the modelling of the transition states by applying geometric constraints, the long range interactions (ion - molecule) in gaseous phase, the reaction sites in gaseous phase and the mass spectroscopy applications. The points of convergence between the investigations of the mass spectroscopy and the theoretical chemistry teams, as well as the purposes guiding the research programs, are discussed. The published papers, the conferences, the congress communications and the thesis, are also reported [fr

  13. Modelling ocean-colour-derived chlorophyll a

    Directory of Open Access Journals (Sweden)

    S. Dutkiewicz

    2018-01-01

    Full Text Available This article provides a proof of concept for using a biogeochemical/ecosystem/optical model with a radiative transfer component as a laboratory to explore aspects of ocean colour. We focus here on the satellite ocean colour chlorophyll a (Chl a product provided by the often-used blue/green reflectance ratio algorithm. The model produces output that can be compared directly to the real-world ocean colour remotely sensed reflectance. This model output can then be used to produce an ocean colour satellite-like Chl a product using an algorithm linking the blue versus green reflectance similar to that used for the real world. Given that the model includes complete knowledge of the (model water constituents, optics and reflectance, we can explore uncertainties and their causes in this proxy for Chl a (called derived Chl a in this paper. We compare the derived Chl a to the actual model Chl a field. In the model we find that the mean absolute bias due to the algorithm is 22 % between derived and actual Chl a. The real-world algorithm is found using concurrent in situ measurement of Chl a and radiometry. We ask whether increased in situ measurements to train the algorithm would improve the algorithm, and find a mixed result. There is a global overall improvement, but at the expense of some regions, especially in lower latitudes where the biases increase. Not surprisingly, we find that region-specific algorithms provide a significant improvement, at least in the annual mean. However, in the model, we find that no matter how the algorithm coefficients are found there can be a temporal mismatch between the derived Chl a and the actual Chl a. These mismatches stem from temporal decoupling between Chl a and other optically important water constituents (such as coloured dissolved organic matter and detrital matter. The degree of decoupling differs regionally and over time. For example, in many highly seasonal regions, the timing of initiation

  14. Allergic reactions

    Science.gov (United States)

    ... that don't bother most people (such as venom from bee stings and certain foods, medicines, and pollens) can ... person. If the allergic reaction is from a bee sting, scrape the ... more venom. If the person has emergency allergy medicine on ...

  15. Relationship between color (instrumental and visual) and chlorophyll contents in soybean seeds during ripening.

    Science.gov (United States)

    Sinnecker, Patrícia; Gomes, M Salete O; Arêas, José A G; Lanfer-Marquez, Ursula M

    2002-07-03

    The correlation between chlorophyll content and quantitative color parameters was investigated in order to find an indirect method for predicting green pigment in ripening soybean seeds. Five Brazilian soybean varieties harvested at different maturity stages (R(6) to R(8) according to the scale of Fehr & Caviness) and dried under two conditions (in oven at 40 degrees C with circulating air and at ambient temperature around 25 degrees C) were analyzed in two consecutive years. The slow-dried seeds at 25 degrees C lost chlorophyll faster, whereas drying at 40 degrees C did not result in yellowing of seeds. High and significant linear correlations between a value and total chlorophyll were obtained over the whole maturation period and on both conditions of drying. From an industrial point of view it appears that a value, obtained by the CIE-L*a*b* method, seems to be a good tool to be applied for quality control and classifying soybean seeds for different purposes.

  16. Chlorophyll fluorescence, Orbital and Photosynthesis: practical activities integrating concepts of Chemistry, Physics and Biology

    Directory of Open Access Journals (Sweden)

    Elgion Lucio da Silva Loreto

    2013-11-01

    Full Text Available These laboratory activities explore the relationship between the reserve of energy that occur during photosynthesis and the chlorophyll fluorescence emission when in solution as opposed to absence of fluorescence when the chlorophyll are in intact chloroplasts. This proposal can be used as short demo or as  activities with longer duration, to show chlorophyll's properties associated with the photosynthesis. The materials proposed for the implementation of the activities are simple, and possible to building it by the students, enabling the development of various skills and experimental proposals. The protocols are based on observations and record key questions to continue the execution. During the activities, questions promotes pauses for moments of reflection and review of concepts. At the end are presented and discussed proposals for development of interdisciplinary projects.

  17. Estimation of photosynthesis in cyanobacteria by pulse-amplitude modulation chlorophyll fluorescence: problems and solutions.

    Science.gov (United States)

    Ogawa, Takako; Misumi, Masahiro; Sonoike, Kintake

    2017-09-01

    Cyanobacteria are photosynthetic prokaryotes and widely used for photosynthetic research as model organisms. Partly due to their prokaryotic nature, however, estimation of photosynthesis by chlorophyll fluorescence measurements is sometimes problematic in cyanobacteria. For example, plastoquinone pool is reduced in the dark-acclimated samples in many cyanobacterial species so that conventional protocol developed for land plants cannot be directly applied for cyanobacteria. Even for the estimation of the simplest chlorophyll fluorescence parameter, F v /F m , some additional protocol such as addition of DCMU or illumination of weak blue light is necessary. In this review, those problems in the measurements of chlorophyll fluorescence in cyanobacteria are introduced, and solutions to those problems are given.

  18. A schematic model for energy and charge transfer in the chlorophyll complex

    DEFF Research Database (Denmark)

    Bohr, Henrik; Malik, F.B.

    2011-01-01

    A theory for simultaneous charge and energy transfer in the carotenoid-chlorophyll-a complex is presented here and discussed. The observed charge transfer process in these chloroplast complexes is reasonably explained in terms of this theory. In addition, the process leads to a mechanism to drive...... an electron in a lower to a higher-energy state, thus providing a mechanism for the ejection of the electron to a nearby molecule (chlorophyll) or into the environment. The observed lifetimes of the electronically excited states are in accord/agreement with the investigations of Sundström et al....... and are in the range of pico-seconds and less. The change in electronic charge distribution in internuclear space as the system undergoes an electronic transition to a higher-energy state could, under appropriate physical conditions, lead to oscillating dipoles capable of transmitting energy from the carotenoid-chlorophylls...

  19. Direct effect of acid rain on leaf chlorophyll content of terrestrial plants in China.

    Science.gov (United States)

    Du, Enzai; Dong, Dan; Zeng, Xuetong; Sun, Zhengzhong; Jiang, Xiaofei; de Vries, Wim

    2017-12-15

    Anthropogenic emissions of acid precursors in China have resulted in widespread acid rain since the 1980s. Although efforts have been made to assess the indirect, soil mediated ecological effects of acid rain, a systematic assessment of the direct foliage injury by acid rain across terrestrial plants is lacking. Leaf chlorophyll content is an important indicator of direct foliage damage and strongly related to plant productivity. We synthesized data from published literature on experiments of simulated acid rain, by directly exposing plants to acid solutions with varying pH levels, to assess the direct effect of acid rain on leaf chlorophyll content across 67 terrestrial plants in China. Our results indicate that acid rain substantially reduces leaf chlorophyll content by 6.71% per pH unit across the recorded plant species. The direct reduction of leaf chlorophyll content due to acid rain exposure showed no significant difference across calcicole, ubiquist or calcifuge species, implying that soil acidity preference does not influence the sensitivity to leaf injury by acid rain. On average, the direct effects of acid rain on leaf chlorophyll on trees, shrubs and herbs were comparable. The effects, however varied across functional groups and economic use types. Specifically, leaf chlorophyll content of deciduous species was more sensitive to acid rain in comparison to evergreen species. Moreover, vegetables and fruit trees were more sensitive to acid rain than other economically used plants. Our findings imply a potential production reduction and economic loss due to the direct foliage damage by acid rain. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Plant leaf chlorophyll content retrieval based on a field imaging spectroscopy system.

    Science.gov (United States)

    Liu, Bo; Yue, Yue-Min; Li, Ru; Shen, Wen-Jing; Wang, Ke-Lin

    2014-10-23

    A field imaging spectrometer system (FISS; 380-870 nm and 344 bands) was designed for agriculture applications. In this study, FISS was used to gather spectral information from soybean leaves. The chlorophyll content was retrieved using a multiple linear regression (MLR), partial least squares (PLS) regression and support vector machine (SVM) regression. Our objective was to verify the performance of FISS in a quantitative spectral analysis through the estimation of chlorophyll content and to determine a proper quantitative spectral analysis method for processing FISS data. The results revealed that the derivative reflectance was a more sensitive indicator of chlorophyll content and could extract content information more efficiently than the spectral reflectance, which is more significant for FISS data compared to ASD (analytical spectral devices) data, reducing the corresponding RMSE (root mean squared error) by 3.3%-35.6%. Compared with the spectral features, the regression methods had smaller effects on the retrieval accuracy. A multivariate linear model could be the ideal model to retrieve chlorophyll information with a small number of significant wavelengths used. The smallest RMSE of the chlorophyll content retrieved using FISS data was 0.201 mg/g, a relative reduction of more than 30% compared with the RMSE based on a non-imaging ASD spectrometer, which represents a high estimation accuracy compared with the mean chlorophyll content of the sampled leaves (4.05 mg/g). Our study indicates that FISS could obtain both spectral and spatial detailed information of high quality. Its image-spectrum-in-one merit promotes the good performance of FISS in quantitative spectral analyses, and it can potentially be widely used in the agricultural sector.