Molecular genetic and molecular evolutionary studies on the bacteriochlorophyll synthesis genes of Rhodobacter capsulatus

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Burke-Agueero, Donald H. [Univ. of California, Berkeley, CA (United States)

1992-08-01

Rhodobacter capsulatus, purple bacterium capable of either aerobic or photosynthetic growth, has proven to be very useful in genetic studies of photosynthesis. Forty-four genes clustered together within a 46 kilobase region are required to establish photosynthetic ability in R. capsulatus. Approximately twenty of these genes are involved in bacteriochlorophyll synthesis of which eight ``bch`` genes are the subject of this thesis. Six of these genes were found to code for the two ring reductases. The first converts protochlorophyllide (PChlide) into a chlorin, the immediate precursor to chlorophyll a, and then into a bacteriochlorin. Each reductase is shown to be made up of three subunits. PChlide reductase is coded by the genes bchN, bchB, and bchL. Proteins with amino acid sequences markedly similar to those of bchN and bchL have been shown in other organisms to be required for chlorophyll synthesis; hence, their designation as chlN and chlB. A third chloroplast-encoded gene of heretofore unknown function shares amino acid identities with bchB and is probably the third subunit of the plant PChlide reductase. The bchA locus, which encodes the chlorin reductase, is found to be made up of three separate, translationally coupled genes, referred to as bchX, bchY, and bchZ. Amino acid similarities between bchX, bchL, and the nitrogenase reductase protein nifH suggest that all three classes of proteins share certain three-dimensional structural features, including elements that are central to the enzymatic mechanism of nifH. PChlide reductase and chlorin reductase are clearly derived from a common ancestor. Several lines of analysis suggests the ancestor of both enzyme systems reduced PChlide twice to produce bacteriochlorophyll supporting the concept bacteriochlorophyll as the ancestral reaction center pigment.

Effect of light-dark cycles on hydrogen and poly-β-hydroxybutyrate production by a photoheterotrophic culture and Rhodobacter capsulatus using a dark fermentation effluent as substrate.

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Montiel Corona, Virginia; Le Borgne, Sylvie; Revah, Sergio; Morales, Marcia

2017-02-01

A Rhodobacter capsulatus strain and a photoheterotrophic culture (IZT) were cultivated to produce hydrogen under different light-dark cycles. A dark fermentation effluent (DFE) was used as substrate. It was found that IZT culture had an average cumulative hydrogen production (Paccum H 2 ) of 1300±43mLH 2 L -1 under continuous illumination and light-dark cycles of 30 or 60min. In contrast, R. capsulatus reduced its Paccum H 2 by 20% under 30:30min light-dark cycles, but tripled its poly-β-hydroxybutyrate (PHB) content (308±2mgPHB gdw -1 ) compared to continuous illumination. The highest PHB content by IZT culture was 178±10mgPHB gdw -1 under 15:15min light-dark cycles. PCR-DGGE analysis revealed that the IZT culture was mainly composed of Rhodopseudomonas palustris identified with high nucleotide similarity (99%). The evaluated cultures might be used for hydrogen and PHB production. They might provide energy savings by using light-dark cycles and DFE valorization. Copyright © 2016 Elsevier Ltd. All rights reserved.

The SOS Response Master Regulator LexA Regulates the Gene Transfer Agent of Rhodobacter capsulatus and Represses Transcription of the Signal Transduction Protein CckA.

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Kuchinski, Kevin S; Brimacombe, Cedric A; Westbye, Alexander B; Ding, Hao; Beatty, J Thomas

2016-02-01

The gene transfer agent of Rhodobacter capsulatus (RcGTA) is a genetic exchange element that combines central aspects of bacteriophage-mediated transduction and natural transformation. RcGTA particles resemble a small double-stranded DNA bacteriophage, package random ∼4-kb fragments of the producing cell genome, and are released from a subpopulation (SOS response in many bacteria, as a regulator of RcGTA activity. Deletion of the lexA gene resulted in the abolition of detectable RcGTA production and an ∼10-fold reduction in recipient capability. A search for SOS box sequences in the R. capsulatus genome sequence identified a number of putative binding sites located 5' of typical SOS response coding sequences and also 5' of the RcGTA regulatory gene cckA, which encodes a hybrid histidine kinase homolog. Expression of cckA was increased >5-fold in the lexA mutant, and a lexA cckA double mutant was found to have the same phenotype as a ΔcckA single mutant in terms of RcGTA production. The data indicate that LexA is required for RcGTA production and maximal recipient capability and that the RcGTA-deficient phenotype of the lexA mutant is largely due to the overexpression of cckA. This work describes an unusual phenotype of a lexA mutant of the alphaproteobacterium Rhodobacter capsulatus in respect to the phage transduction-like genetic exchange carried out by the R. capsulatus gene transfer agent (RcGTA). Instead of the expected SOS response characteristic of prophage induction, this lexA mutation not only abolishes the production of RcGTA particles but also impairs the ability of cells to receive RcGTA-borne genes. The data show that, despite an apparent evolutionary relationship to lambdoid phages, the regulation of RcGTA gene expression differs radically. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

In vitro assembly of a prohead-like structure of the Rhodobacter capsulatus gene transfer agent

International Nuclear Information System (INIS)

Spano, Anthony J.; Chen, Frank S.; Goodman, Benjamin E.; Sabat, Agnes E.; Simon, Martha N.; Wall, Joseph S.; Correia, John J.; McIvor, Wilson; Newcomb, William W.; Brown, Jay C.; Schnur, Joel M.; Lebedev, Nikolai

2007-01-01

The gene transfer agent (GTA) is a phage-like particle capable of exchanging double-stranded DNA fragments between cells of the photosynthetic bacterium Rhodobacter capsulatus. Here we show that the major capsid protein of GTA, expressed in E. coli, can be assembled into prohead-like structures in the presence of calcium ions in vitro. Transmission electron microscopy (TEM) of uranyl acetate staining material and thin sections of glutaraldehyde-fixed material demonstrates that these associates have spherical structures with diameters in the range of 27-35 nm. The analysis of scanning TEM images revealed particles of mass ∼ 4.3 MDa, representing 101 ± 11 copies of the monomeric subunit. The establishment of this simple and rapid method to form prohead-like particles permits the GTA system to be used for genome manipulation within the photosynthetic bacterium, for specific targeted drug delivery, and for the construction of biologically based distributed autonomous sensors for environmental monitoring

Potential use of thermophilic dark fermentation effluents in photofermentative hydrogen production by Rhodobacter capsulatus

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Ozgura, E.; Afsar, N.; Eroglu, I. [Middle East Technical University, Department of Chemical Engineering, 06531 Ankara (Turkey); De Vrije, T.; Claassen, P.A.M. [Wageningen UR, Agrotechnology and Food Sciences Group, Wageningen UR, P.O. Box 17, 6700 AA Wageningen (Netherlands); Yucel, M.; Gunduz, U. [Middle East Technical University, Department of Biology, 06531 Ankara (Turkey)

2010-12-15

Biological hydrogen production by a sequential operation of dark and photofermentation is a promising route to produce hydrogen. The possibility of using renewable resources, like biomass and agro-industrial wastes, provides a dual effect of sustainability in biohydrogen production and simultaneous waste removal. In this study, photofermentative hydrogen production on effluents of thermophilic dark fermentations on glucose, potato steam peels (PSP) hydrolysate and molasses was investigated in indoor, batch operated bioreactors. An extreme thermophile Caldicellulosiruptor saccharolyticus was used in the dark fermentation step, and Rhodobacter capsulatus (DSM1710) was used in the photofermentation step. Addition of buffer, Fe and Mo to dark fermentor effluents (DFEs) improved the overall efficiency of hydrogen production. The initial acetate concentration in the DFE needed to be adjusted to 30-40 mM by dilution to increase the yield of hydrogen in batch light-supported fermentations. The thermophilic DFEs are suitable for photofermentative hydrogen production, provided that they are supplemented with buffer and nutrients. The overall hydrogen yield of the two-step fermentations was higher than the yield of single step dark fermentations.

Field evidence for the potential of Rhodobacter capsulatus as Biofertilizer for flooded rice.

Science.gov (United States)

Gamal-Eldin, Hosny; Elbanna, Khaled

2011-02-01

In a previous study, we evaluated the effects of inoculating rice plants with the phototrophic purple nonsulfur bacterium Rhodobacter capsulatus (Rc) on growth and yield of rice in pots and lysimeter experiments and the results obtained have been highly encouraging. In this study, we carried out two field experiments: one in the experimental farm of the Faculty of Agriculture, Fayoum University, and the second in a farmer's field in Kafr El-sheikh, to assess the effects of Rc on growth and yield of rice in comparison and in combination with chemical nitrogen fertilizer (CNF) and farmyard manure. The results indicated that both biological and grain yields in all the Rc inoculated treatments were significantly higher than those in the uninoculated corresponding treatments in both fields. With regard to grain yield, the major factor for determining the effectiveness of any agricultural treatment, inoculation with Rc in combination with 50% of the recommended CNF rate gave a grain yield that was statistically equivalent to that obtained with 100% of the recommended CNF rate. These results provide a clear evidence for the potential of Rc as biofertilizer for flooded rice under field conditions.

The photosynthetic bacteria Rhodobacter capsulatus and Synechocystis sp. PCC 6803 as new hosts for cyclic plant triterpene biosynthesis.

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Anita Loeschcke

Full Text Available Cyclic triterpenes constitute one of the most diverse groups of plant natural products. Besides the intriguing biochemistry of their biosynthetic pathways, plant triterpenes exhibit versatile bioactivities, including antimicrobial effects against plant and human pathogens. While prokaryotes have been extensively used for the heterologous production of other classes of terpenes, the synthesis of cyclic triterpenes, which inherently includes the two-step catalytic formation of the universal linear precursor 2,3-oxidosqualene, is still a major challenge. We thus explored the suitability of the metabolically versatile photosynthetic α-proteobacterium Rhodobacter capsulatus SB1003 and cyanobacterium Synechocystis sp. PCC 6803 as alternative hosts for biosynthesis of cyclic plant triterpenes. Therefore, 2,3-oxidosqualene production was implemented and subsequently combined with different cyclization reactions catalyzed by the representative oxidosqualene cyclases CAS1 (cycloartenol synthase, LUP1 (lupeol synthase, THAS1 (thalianol synthase and MRN1 (marneral synthase derived from model plant Arabidopsis thaliana. While successful accumulation of 2,3-oxidosqualene could be detected by LC-MS analysis in both hosts, cyclase expression resulted in differential production profiles. CAS1 catalyzed conversion to only cycloartenol, but expression of LUP1 yielded lupeol and a triterpenoid matching an oxidation product of lupeol, in both hosts. In contrast, THAS1 expression did not lead to cyclic product formation in either host, whereas MRN1-dependent production of marnerol and hydroxymarnerol was observed in Synechocystis but not in R. capsulatus. Our findings thus indicate that 2,3-oxidosqualene cyclization in heterologous phototrophic bacteria is basically feasible but efficient conversion depends on both the respective cyclase enzyme and individual host properties. Therefore, photosynthetic α-proteo- and cyanobacteria are promising alternative candidates

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

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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)

Reprint of “Extracellular production of tellurium nanoparticles by the photosynthetic bacterium Rhodobacter capsulatus”

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Borghese, Roberto, E-mail: roberto.borghese@unibo.it [Dept. of Pharmacy and Biotechnology, University of Bologna (Italy); Brucale, Marco [Institute for the Study of Nanostructured Materials (CNR-ISMN), Rome (Italy); Fortunato, Gianuario [Dept. of Pharmacy and Biotechnology, University of Bologna (Italy); Lanzi, Massimiliano [Dept. of Industrial Chemistry “Toso Montanari”, University of Bologna (Italy); Mezzi, Alessio [Institute for the Study of Nanostructured Materials (CNR-ISMN), Rome (Italy); Valle, Francesco; Cavallini, Massimiliano [Institute for the Study of Nanostructured Materials (CNR-ISMN), Bologna (Italy); Zannoni, Davide [Dept. of Pharmacy and Biotechnology, University of Bologna (Italy)

2017-02-15

Highlights: • Tellurite is reduced by R. capsulatus as cytosolic tellurium nanoprecipitates TeNPs. • Lawsone allows R. capsulatus to produce extracellular TeNPs. • Extracellular TeNPs production depends on the carbon source used for cells growth. • Both lawsone concentration and the incubation time determine the TeNPs size. • Extracellular TeNPs are coated with extracellular polymeric substances (EPS). - Abstract: The toxic oxyanion tellurite (TeO{sub 3}{sup 2−}) is acquired by cells of Rhodobacter capsulatus grown anaerobically in the light, via acetate permease ActP2 and then reduced to Te{sup 0} in the cytoplasm as needle-like black precipitates. Interestingly, photosynthetic cultures of R. capsulatus can also generate Te{sup 0} nanoprecipitates (TeNPs) outside the cells upon addition of the redox mediator lawsone (2-hydroxy-1,4-naphtoquinone). TeNPs generation kinetics were monitored to define the optimal conditions to produce TeNPs as a function of various carbon sources and lawsone concentration. We report that growing cultures over a 10 days period with daily additions of 1 mM tellurite led to the accumulation in the growth medium of TeNPs with dimensions from 200 up to 600–700 nm in length as determined by atomic force microscopy (AFM). This result suggests that nucleation of TeNPs takes place over the entire cell growth period although the addition of new tellurium Te{sup 0} to pre-formed TeNPs is the main strategy used by R. capsulatus to generate TeNPs outside the cells. Finally, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FT-IR) analysis of TeNPs indicate they are coated with an organic material which keeps the particles in solution in aqueous solvents.

Dietary Effect of Selenium-enriched Radish Sprouts, Vitamin E, and Rhodobacter capsulatus on Hypocholesterolemia and Immunity of Broiler

Directory of Open Access Journals (Sweden)

Tsujii H

2017-06-01

Full Text Available The study was designed to investigate the effects of dietary Selenium-enriched radish sprouts (Se-RS, Vitamin E (Vit E, and Rhodobacter capsulatus (RC on immunity, cholesterol concentration, and fatty acid composition in broiler meat. A total of 100 two-week-old male broiler chicks were randomly assigned into five dietary groups: I Control; II Se-RS (5 μg/kg Se-RS; III Se-RS+RC (5 μg/kg Se-RS + 0.2 g/kg RC; IV Se-RS+Vit E (5 μg/kg Se-RS + 50 mg/kg Vit E and V Se-RS+RC+Vit E (5 μg/kg Se-RS + 0.2 g/kg RC + 50 mg/kg Vit E. Diets and clean drinking water were offered ad libitum. After the end of 3-wk of feeding period, serum cholesterol and triglycerides concentrations were lower (P < 0.05 in broilers fed Se-RS + RC + Vit E supplemented diet compared to the control diet. At the end of the 6-wk feeding period, birds fed the Se-RS+RC+Vit E diet significantly (P < 0.05 reduced cholesterol and triglycerides concentrations and improved the ratio of unsaturated fatty acids to saturated fatty acids in broiler meat. The highest (P < 0.05 number of leukocytes was observed in broilers fed Se-RS+RC+Vit E supplemented diet. Foot web index and weights of spleen, bursa, and thymus were significantly (P < 0.05 higher in birds fed Se-RS+RC+Vit E compared to the control diet. Our findings suggest that there are dual benefits of supplementing broiler diets with Se-RS+RC+Vit E because of improvements in the bird’s immunity and meat quality that is important for health conscious consumers.

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

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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.

Nicotinamide nucleotide transhydrogenase from Rhodobacter capsulatus; the H+/H- ratio and the activation state of the enzyme during reduction of acetyl pyridine adenine dinucleotide.

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Palmer, T; Jackson, J B

1992-02-21

Chromatophores from Rhodobacter capsulatus were incubated in the dark with NADPH and acetylpyridineadenine dinucleotide (AcPdAD+) in the presence of different concentrations of myxothiazol. The transhydrogenase activity was monitored until an appropriate mass action ratio, [AcPdAD+][NADPH]/[AcPdADH][NADP+], was reached. The sample was then illuminated and the initial rate of either AcPdAD+ reduction by NADPH or AcPdADH oxidation by NADP+ was recorded. The ratio of H+ translocated per H- equivalent transferred by transhydrogenase was calculated from the value of the membrane potential (delta pH = 0) at which illumination caused no net reaction in either direction. The mean value for the H+/H- ratio was 0.55. At greater values of [AcPdAD+][NADPH]/[AcPdADH][NADP+] than were employed in the above experiments and over a wider range of concentrations of myxothiazol, it was found that incremental increases in the membrane potential always gave rise to a decrease, never an increase in the rate of AcPdAD+ reduction. In contrast to the H(+)-ATP synthase, there is no evidence of any activation/deactivation of H(+)-transhydrogenase by the protonmotive force.

Plasmon waveguide resonance spectroscopic evidence for differential binding of oxidized and reduced rhodobacter capsulatus cytochrome c(2) to the cytochrome bc(1) complex mediated by the conformation of the rieske iron-sulfur protein

International Nuclear Information System (INIS)

Devanathan, S.; Salamon, Z.; Tollin, G.; Fitch, J.C.; Meyer, T.E.; Berry, E.A.; Cusanovich, M.A.

2007-01-01

The dissociation constants for the binding of Rhodobacter capsulatus cytochrome c2 and its K93P mutant to the cytochrome bc1 complex embedded in a phospholipid bilayer were measured by plasmon waveguide resonance spectroscopy in the presence and absence of the inhibitor stigmatellin. The reduced form of cytochrome c2 strongly binds to reduced cytochrome bc1 (Kd = 0.02 M) but binds much more weakly to the oxidized form (Kd = 3.1 M). In contrast, oxidized cytochrome c2 binds to oxidized cytochrome bc1 in a biphasic fashion with Kd values of 0.11 and 0.58 M. Such a biphasic interaction is consistent with binding to two separate sites or conformations of oxidized cytochrome c2 and/or cytochrome bc1. However, in the presence of stigmatellin, we find that oxidized cytochrome c2 binds to oxidized cytochrome bc1 in a monophasic fashion with high affinity (Kd = 0.06 M) and reduced cytochrome c2 binds less strongly (Kd = 0.11 M) but ∼30-fold more tightly than in the absence of stigmatellin. Structural studies with cytochrome bc1, with and without the inhibitor stigmatellin, have led to the proposal that the Rieske protein is mobile, moving between the cytochrome b and cytochrome c1 components during turnover. In one conformation, the Rieske protein binds near the heme of cytochrome c1, while the cytochrome c2 binding site is also near the cytochrome c1 heme but on the opposite side from the Rieske site, where cytochrome c2 cannot directly interact with Rieske. However, the inhibitor, stigmatellin, freezes the Rieske protein iron-sulfur cluster in a conformation proximal to cytochrome b and distal to cytochrome c1. We conclude from this that the dual conformation of the Rieske protein is primarily responsible for biphasic binding of oxidized cytochrome c2 to cytochrome c1. This optimizes turnover by maximizing binding of the substrate, oxidized cytochrome c2, when the iron-sulfur cluster is proximal to cytochrome b and minimizing binding of the product, reduced cytochrome c

A molecular genetic analysis of carotenoid biosynthesis and the effects of carotenoid mutations on other photosynthetic genes in Rhodobacter capsulatus

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Armstrong, G.A.

1989-04-01

The nine known R. capsulatus carotenoid genes are contained within the 46 kilobase (kb) photosynthesis gene cluster. An 11 kb subcluster containing eight of these genes has been cloned and its nucleotide sequence determined. A new gene, crtK, has been located in the middle of the subcluster. The carotenoid gene cluster contains sequences homologous to Escherichia coli ..omega../sup 70/ promoters, rho-independent transcription terminators, and prokaryotic transcriptional factor binding sites. The phenotypes and genotypes of ten transposon Tn5.7 insertion mutations within the carotenoid gene cluster have been analyzed, by characterization of the carotenoids accumulated and high resolution mapping of the Tn5.7 insertions. The enzymatic blockages in previously uncharacterized early carotenoid mutants have been determined using a new in vitro synthesis system, suggesting specific roles for the CrtB and CrtE gene products. The expression of six of the eight carotenoid genes in the cluster is induced upon the shift from dark chemoheterotrophic to anaerobic photosynthetic growth. The magnitude of the induction is equivalent to that of genes encoding structural photosynthesis polypeptides, although the carotenoid genes are induced earlier after the growth shift. Different means of regulating photosynthesis genes in R. capsulatus are discussed, and a rationale for the temporal pattern of expression of the carotenoid genes during photosynthetic adaptation is presented. Comparison of the deduced amino acid sequences of the two dehydrogenases of the R. capsulatus carotenoid biosynthesis pathway reveals two regions of strong similarity. The effect of carotenoid mutations on the photosynthetic phenotype has been studied by examining growth rates, pigments, pigment-protein complexes and gene expression for a complete set of carotenoid mutants. 161 refs.

A molecular genetic analysis of carotenoid biosynthesis and the effects of carotenoid mutations on other photosynthetic genes in Rhodobacter capsulatus

International Nuclear Information System (INIS)

Armstrong, G.A.

1989-04-01

The nine known R. capsulatus carotenoid genes are contained within the 46 kilobase (kb) photosynthesis gene cluster. An 11 kb subcluster containing eight of these genes has been cloned and its nucleotide sequence determined. A new gene, crtK, has been located in the middle of the subcluster. The carotenoid gene cluster contains sequences homologous to Escherichia coli ω 70 promoters, rho-independent transcription terminators, and prokaryotic transcriptional factor binding sites. The phenotypes and genotypes of ten transposon Tn5.7 insertion mutations within the carotenoid gene cluster have been analyzed, by characterization of the carotenoids accumulated and high resolution mapping of the Tn5.7 insertions. The enzymatic blockages in previously uncharacterized early carotenoid mutants have been determined using a new in vitro synthesis system, suggesting specific roles for the CrtB and CrtE gene products. The expression of six of the eight carotenoid genes in the cluster is induced upon the shift from dark chemoheterotrophic to anaerobic photosynthetic growth. The magnitude of the induction is equivalent to that of genes encoding structural photosynthesis polypeptides, although the carotenoid genes are induced earlier after the growth shift. Different means of regulating photosynthesis genes in R. capsulatus are discussed, and a rationale for the temporal pattern of expression of the carotenoid genes during photosynthetic adaptation is presented. Comparison of the deduced amino acid sequences of the two dehydrogenases of the R. capsulatus carotenoid biosynthesis pathway reveals two regions of strong similarity. The effect of carotenoid mutations on the photosynthetic phenotype has been studied by examining growth rates, pigments, pigment-protein complexes and gene expression for a complete set of carotenoid mutants. 161 refs

Functional assignment of gene AAC16202.1 from Rhodobacter capsulatus SB1003: new insights into the bacterial SDR sorbitol dehydrogenases family.

Science.gov (United States)

Sola-Carvajal, Agustín; García-García, María Inmaculada; Sánchez-Carrón, Guiomar; García-Carmona, Francisco; Sánchez-Ferrer, Alvaro

2012-11-01

Short-chain dehydrogenases/reductases (SDR) constitute one of the largest enzyme superfamilies with over 60,000 non-redundant sequences in the database, many of which need a correct functional assignment. Among them, the gene AAC16202.1 (NCBI) from Rhodobacter capsulatus SB1003 has been assigned in Uniprot both as a sorbitol dehydrogenase (#D5AUY1) and, as an N-acetyl-d-mannosamine dehydrogenase (#O66112), both enzymes being of biotechnological interest. When the gene was overexpressed in Escherichia coli Rosetta (DE3)pLys, the purified enzyme was not active toward N-acetyl-d-mannosamine, whereas it was active toward d-sorbitol and d-fructose. However, the relative activities toward xylitol and l-iditol (0.45 and 6.9%, respectively) were low compared with that toward d-sorbitol. Thus, the enzyme could be considered sorbitol dehydrogenase (SDH) with very low activity toward xylitol, which could increase its biotechnological interest for determining sorbitol without the unspecific cross-determination of added xylitol in food and pharma compositions. The tetrameric enzyme (120 kDa) showed similar catalytic efficiency (2.2 × 10(3) M(-1) s(-1)) to other sorbitol dehydrogenases for d-sorbitol, with an optimum pH of 9.0 and an optimum temperature of 37 °C. The enzyme was also more thermostable than other reported SDH, ammonium sulfate being the best stabilizer in this respect, increasing the melting temperature (T(m)) up to 52.9 °C. The enzyme can also be considered as a new member of the Zn(2+) independent SDH family since no effect on activity was detected in the presence of divalent cations or chelating agents. Finally, its in silico analysis enabled the specific conserved sequence blocks that are the fingerprints of bacterial sorbitol dehydrogenases and mainly located at C-terminal of the protein, to be determined for the first time. This knowledge will facilitate future data curation of present databases and a better functional assignment of newly described

Bacterial PerO Permeases Transport Sulfate and Related Oxyanions.

Science.gov (United States)

Hoffmann, Marie-Christine; Pfänder, Yvonne; Tintel, Marc; Masepohl, Bernd

2017-07-15

Rhodobacter capsulatus synthesizes the high-affinity ABC transporters CysTWA and ModABC to specifically import the chemically related oxyanions sulfate and molybdate, respectively. In addition, R. capsulatus has the low-affinity permease PerO acting as a general oxyanion transporter, whose elimination increases tolerance to molybdate and tungstate. Although PerO-like permeases are widespread in bacteria, their function has not been examined in any other species to date. Here, we present evidence that PerO permeases from the alphaproteobacteria Agrobacterium tumefaciens , Dinoroseobacter shibae , Rhodobacter sphaeroides , and Sinorhizobium meliloti and the gammaproteobacterium Pseudomonas stutzeri functionally substitute for R. capsulatus PerO in sulfate uptake and sulfate-dependent growth, as shown by assimilation of radioactively labeled sulfate and heterologous complementation. Disruption of perO genes in A. tumefaciens , R. sphaeroides , and S. meliloti increased tolerance to tungstate and, in the case of R. sphaeroides , to molybdate, suggesting that heterometal oxyanions are common substrates of PerO permeases. This study supports the view that bacterial PerO permeases typically transport sulfate and related oxyanions and, hence, form a functionally conserved permease family. IMPORTANCE Despite the widespread distribution of PerO-like permeases in bacteria, our knowledge about PerO function until now was limited to one species, Rhodobacter capsulatus In this study, we showed that PerO proteins from diverse bacteria are functionally similar to the R. capsulatus prototype, suggesting that PerO permeases form a conserved family whose members transport sulfate and related oxyanions. Copyright © 2017 American Society for Microbiology.

Diverse Arrangement of Photosynthetic Gene Clusters in Aerobic Anoxygenic Phototrophic Bacteria

Czech Academy of Sciences Publication Activity Database

Zheng, Q.; Zhang, R.; Koblížek, Michal; Boldareva, Ekaterina; Yurkov, V.; Shi, Y.

2011-01-01

Roč. 6, č. 9 (2011), s. 1-7 E-ISSN 1932-6203 R&D Projects: GA ČR GAP501/10/0221 Institutional research plan: CEZ:AV0Z50200510 Keywords : RHODOBACTER-CAPSULATUS * CITROMICROBIUM-BATHYOMARINUM * REACTION CENTERS Subject RIV: EE - Microbiology, Virology Impact factor: 4.092, year: 2011

Carotenoid biosynthesis in bacteria: In vitro studies of a crt/bch transcription factor from Rhodobacter capsulatus and carotenoid enzymes from Erwinia herbicola

Energy Technology Data Exchange (ETDEWEB)

O' Brien, D.A.

1992-11-01

A putative transcription factor in Rhodobactor capsulatus which binds upstream of the crt and bch pigment biosynthesis operons and appears to play a role in the adaptation of the organism from the aerobic to the anaerobic-photosynthetic growth mode was characterized. Chapter 2 describes the identification of this factor through an in vitro mobility shift assay, as well as the determination of its binding properties and sequence specificity. Chapter 3 focuses on the isolation of this factor. Biochemistry of later carotenoid biosynthesis enzymes derived from the non-photosynthetic bacterium, Erwinia herbicola. Chapter 4 describes the separate overexpression and in vitro analysis of two enzymes involved in the main sequence of the carotenoid biosynthesis pathway, lycopene cyclase and 5-carotene hydroxylase. Chapter 5 examines the overexpression and enzymology of functionally active zeaxanthin glucosyltransferase, an enzyme which carries out a more unusual transformation, converting a carotenoid into its more hydrophilic mono- and diglucoside derivatives. In addition, amino acid homology with other glucosyltransferases suggests a putative binding site for the UDP-activated glucose substrate.

Hemifluorinated maltose-neopentyl glycol (HF-MNG) amphiphiles for membrane protein stabilisation.

Science.gov (United States)

Cho, Kyung Ho; Byrne, Bernadette; Chae, Pil Seok

2013-03-04

SOAP OPERA: Fluorinated amphiphile F4-MNG confers greater stability on Rhodobacter capsulatus superassembly relative to conventional detergents and nonfluorinated MNGs. Such amphiphiles are attractive as tools for membrane science because of their ease of preparation and structure variation. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Bioremediation of lead contaminated soil with Rhodobacter sphaeroides.

Science.gov (United States)

Li, Xiaomin; Peng, Weihua; Jia, Yingying; Lu, Lin; Fan, Wenhong

2016-08-01

Bioremediation with microorganisms is a promising technique for heavy metal contaminated soil. Rhodobacter sphaeroides was previously isolated from oil field injection water and used for bioremediation of lead (Pb) contaminated soil in the present study. Based on the investigation of the optimum culturing conditions and the tolerance to Pb, we employed the microorganism for the remediation of Pb contaminated soil simulated at different contamination levels. It was found that the optimum temperature, pH, and inoculum size for R. sphaeroides is 30-35 °C, 7, and 2 × 10(8) mL(-1), respectively. Rhodobacter sphaeroides did not remove the Pb from soil but did change its speciation. During the bioremediation process, more available fractions were transformed to less accessible and inert fractions; in particular, the exchangeable phase was dramatically decreased while the residual phase was substantially increased. A wheat seedling growing experiment showed that Pb phytoavailability was reduced in amended soils. Results inferred that the main mechanism by which R. sphaeroides treats Pb contaminated soil is the precipitation formation of inert compounds, including lead sulfate and lead sulfide. Although the Pb bioremediation efficiency on wheat was not very high (14.78% root and 24.01% in leaf), R. sphaeroides remains a promising alternative for Pb remediation in contaminated soil. Copyright © 2016 Elsevier Ltd. All rights reserved.

Oxidation of hydroxylamine by cytochrome P-460 of the obligate methylotroph Methylococcus capsulatus Bath.

Science.gov (United States)

Zahn, J A; Duncan, C; DiSpirito, A A

1994-01-01

An enzyme capable of the oxidation of hydroxylamine to nitrite was isolated from the obligate methylotroph Methylococcus capsulatus Bath. The absorption spectra in cell extracts, electron paramagnetic resonance spectra, molecular weight, covalent attachment of heme group to polypeptide, and enzymatic activities suggest that the enzyme is similar to cytochrome P-460, a novel iron-containing protein previously observed only in Nitrosomonas europaea. The native and subunit molecular masses of the M. capsulatus Bath protein were 38,900 and 16,390 Da, respectively; the isoelectric point was 6.98. The enzyme has approximately one iron and one copper atom per subunit. The electron paramagnetic resonance spectrum of the protein showed evidence for a high-spin ferric heme. In contrast to the enzyme from N. europaea, a 13-nm blue shift in the soret band of the ferrocytochrome (463 nm in cell extracts to 450 nm in the final sample) occurred during purification. The amino acid composition and N-terminal amino acid sequence of the enzyme from M. capsulatus Bath was similar but not identical to those of cytochrome P-460 of N. europaea. In cell extracts, the identity of the biological electron acceptor is as yet unestablished. Cytochrome c-555 is able to accept electrons from cytochrome P-460, although the purified enzyme required phenazine methosulfate for maximum hydroxylamine oxidation activity (specific activity, 366 mol of O2 per s per mol of enzyme). Hydroxylamine oxidation rates were stimulated approximately 2-fold by 1 mM cyanide and 1.5-fold by 0.1 mM 8-hydroxyquinoline. Images PMID:7928947

Real-time monitoring of intracellular redox changes in Methylococcus capsulatus (Bath) for efficient bioconversion of methane to methanol.

Science.gov (United States)

Ishikawa, Masahito; Tanaka, Yuya; Suzuki, Risa; Kimura, Kota; Tanaka, Kenya; Kamiya, Kazuhide; Ito, Hidehiro; Kato, Souichiro; Kamachi, Toshiaki; Hori, Katsutoshi; Nakanishi, Shuji

2017-10-01

This study aimed to develop a novel method for real-time monitoring of the intracellular redox states in a methanotroph Methylococcus capsulatus, using Peredox as a genetically encoded fluorescent sensor of the NADH:NAD + ratio. As expected, the fluorescence derived from the Peredox-expressing M. capsulatus transformant increased by supplementation of electron donor compounds (methane and formate), while it decreased by specifically inhibiting the methanol oxidation reaction. Electrochemical measurements confirmed that the Peredox fluorescence reliably represents the intracellular redox changes. This study is the first to construct a reliable redox-monitoring method for methanotrophs, which will facilitate to develop more efficient methane-to-methanol bioconversion processes. Copyright © 2017 Elsevier Ltd. All rights reserved.

Methyl sterol and cyclopropane fatty acid composition of Methylococcus capsulatus grown at low oxygen tensions

Science.gov (United States)

Jahnke, L. L.; Nichols, P. D.

1986-01-01

The sterol and fatty acid concentrations for M. capsulatus grown in fed-batch cultures over a wide range of oxygen tensions (0.1-10.6 percent) and at a constant methane level are evaluated. The analyses reveal that the biomass decreases as oxygen levels are lowered; the sterol concentration increases when the oxygen range is between 0.5-1.1 percent and decreases when the oxygen range is below 0.5 percent; and the amount of monounsaturated C16 decreases and the concentration of cyclopropane fatty acids increases after oxygen is reduced. It is noted that growth and membrane synthesis occur at low oxygen concentrations and that the synthesis of membrane lipids responds to growth conditions.

Physiological Investigation Of Rhodobacter Sphaeroides

OpenAIRE

Özmeral, Özge

2013-01-01

Rhodobacter sphaeroides metabolik olarak geniş bir organizasyona sahip olan α-3 mor non-sülfür bir organizmadır. Oksijensiz ortamda R. sphaeroides hücreleri fotosentez, solunum ve fermantasyon yaparak çoğalabilir. R. sphaeroides hücrelerinde bulunan fotosentez yapımından sorumlu olan fotosentetik yapıları oksijenin varlığında oksijen tarafından zarara uğratıldığından fotosentez sadece oksijensiz ortamda meydana gelebilir. R. sphaeroides hücreleri fotosentezi fotoheterotrofik ve fotoototr...

Color-sensitive motility and methanol release responses in Rhodobacter sphaeroides

NARCIS (Netherlands)

Kort, R; Crielaard, W.; Spudich, J L; Hellingwerf, K J

Blue-light-induced repellent and demethylation responses, characteristic of behavioral adaptation, were observed in Rhodobacter sphaeroides. They were analyzed by computer-assisted motion analysis and through the release of volatile tritiated compounds from [methyl-(3)H]methionine-labeled cells,

Parameterization of the prosthetic redox centers of the bacterial cytochrome bc(1) complex for atomistic molecular dynamics simulations

DEFF Research Database (Denmark)

Kaszuba, K.; Postila, P. A.; Cramariuc, O.

2013-01-01

studied in large-scale classical molecular dynamics (MD) simulations. In part, this is due to lack of suitable force field parameters, centered atomic point charges in particular, for the complex's prosthetic redox centers. Accurate redox center charges are needed to depict realistically the inter-molecular...... interactions at different redox stages of the cyt bc(1) complex. Accordingly, here we present high-precision atomic point charges for the metal centers of the cyt bc(1) complex of Rhodobacter capsulatus derived from extensive density functional theory calculations, fitted using the restrained electrostatic...

Identification of Ubiquinol Binding Motifs at the Qo-Site of the Cytochrome bc1 Complex

DEFF Research Database (Denmark)

Barragan, Angela M.; Crofts, Antony R.; Schulten, Klaus

2015-01-01

for the function of the bc1 complex is the initial redox process that involves a bifurcated electron transfer in which the two electrons from a quinol substrate are passed to different electron acceptors in the bc1 complex. The electron transfer is coupled to proton transfer. The overall mechanism of quinol...... all atom molecular dynamics and quantum chemical calculations to reveal the binding modes of quinol at the Qo-site of the bc1 complex from Rhodobacter capsulatus. The calculations suggest a novel configuration of amino acid residues responsible for quinol binding and support a mechanism for proton...

Key role of water in proton transfer at the Q(o)-site of the cytochrome bc(1) complex predicted by atomistic molecular dynamics simulations

DEFF Research Database (Denmark)

Postila, P. A.; Kaszuba, K.; Sarewicz, M.

2013-01-01

of the cyt bc(1) function have remained unclear especially regarding the substrate binding at the Q(o)-site. In this work we address this issue by performing extensive atomistic molecular dynamics simulations with the cyt bc(1) complex of Rhodobacter capsulatus embedded in a lipid bilayer. Based...... on the simulations we are able to show the atom-level binding modes of two substrate forms: quinol (QH(2)) and quinone (Q). The QH(2) binding at the Q(o)-site involves a coordinated water arrangement that produces an exceptionally close and stable interaction between the cyt b and iron sulfur protein subunits...

A structural basis for electron transfer in bacterial photosynthesis

International Nuclear Information System (INIS)

Norris, J.R.; DiMagno, T.J.; Angerhofer, A.; Chang, C.H.; El-Kabbani, O.; Schiffer, M.

1989-01-01

Triplet data for the primary donor in single crystals of bacterial reaction centers of Rhodobacter sphaeroides and Rhodopseudomonas viridis are interpreted in terms of the corresponding x-ray structures. The analysis of electron paramagnetic resonance data from single crystals (triplet zero field splitting and cation and triplet linewidth of the primary special pair donor of bacterial reaction centers) is extended to systems of a non-crystalline nature. A unified interpretation based on frontier molecular orbitals concludes that the special pair behaves like a supermolecule in all wild-type bacteria investigated here. However, in heterodimers of Rb. capsulatus (His M200 changed to Leu or Phe with the result that the M-half of the special pair is converted to bacteriopheophytin) the special pair possesses the EPR properties more appropriately described in terms of a monomer. In all cases the triplet state and cation EPR properties appear to be dominated by the highest occupied molecular orbitals. These conclusions derived from EPR experiments are supplemented by data from Stark spectroscopy of reaction centers from Rb. capsulatus. 41 refs., 3 tabs

ISOLATION AND CHARACTERIZATION OF THE HIGH-AFFINITY K+-TRANSLOCATING ATPASE FROM RHODOBACTER-SPHAEROIDES

NARCIS (Netherlands)

ABEE, T; SIEBERS, A; ALTENDORF, K; KONINGS, WN

1992-01-01

Cells of the purple nonsulfur bacterium Rhodobacter sphaeroides express a high-affinity K+ uptake system when grown in media with low K+ concentrations. A vanadate-sensitive, K+-stimulated and Mg2+-stimulated ATPase was purified from membranes of these cells by solubilization with

Structure of the dimeric PufX-containing core complex of Rhodobacter blasticus by in situ atomic force microscopy.

Science.gov (United States)

Scheuring, Simon; Busselez, Johan; Lévy, Daniel

2005-01-14

We have studied photosynthetic membranes of wild type Rhodobacter blasticus, a closely related strain to the well studied Rhodobacter sphaeroides, using atomic force microscopy. High-resolution atomic force microscopy topographs of both cytoplasmic and periplasmic surfaces of LH2 and RC-LH1-PufX (RC, reaction center) complexes were acquired in situ. The LH2 is a nonameric ring inserted into the membrane with the 9-fold axis perpendicular to the plane. The core complex is an S-shaped dimer composed of two RCs, each encircled by 13 LH1 alpha/beta-heterodimers, and two PufXs. The LH1 assembly is an open ellipse with a topography-free gap of approximately 25 A. The two PufXs, one of each core, are located at the dimer center. Based on our data, we propose a model of the core complex, which provides explanation for the PufX-induced dimerization of the Rhodobacter core complex. The QB site is located facing a approximately 25-A wide gap within LH1, explaining the PufX-favored quinone passage in and out of the core complex.

Bioremediation of cadmium- and zinc-contaminated soil using Rhodobacter sphaeroides.

Science.gov (United States)

Peng, Weihua; Li, Xiaomin; Song, Jingxiang; Jiang, Wei; Liu, Yingying; Fan, Wenhong

2018-04-01

Bioremediation using microorganisms is a promising technique to remediate soil contaminated with heavy metals. In this study, Rhodobacter sphaeroides was used to bioremediate soils contaminated with cadmium (Cd) and zinc (Zn). The study found that the treatment reduced the overall bioavailable fractions (e.g., exchangeable and carbonate bound phases) of Cd and Zn. More stable fractions (e.g., Fe-Mn oxide, organic bound, and residual phases (only for Zn)) increased after bioremediation. A wheat seedling experiment revealed that the phytoavailability of Cd was reduced after bioremediation using R. sphaeroides. After bioremediation, the exchangeable phases of Cd and Zn in soil were reduced by as much as 30.7% and 100.0%, respectively; the Cd levels in wheat leaf and root were reduced by as much as 62.3% and 47.2%, respectively. However, when the soils were contaminated with very high levels of Cd and Zn (Cd 54.97-65.33 mg kg -1 ; Zn 813.4-964.8 mg kg -1 ), bioremediation effects were not clear. The study also found that R. sphaeroides bioremediation in soil can enhance the Zn/Cd ratio in the harvested wheat leaf and root overall. This indicates potentially favorable application in agronomic practice and biofortification. Although remediation efficiency in highly contaminated soil was not significant, R. sphaeroides may be potentially and practically applied to the bioremediation of soils co-contaminated by Cd and Zn. Copyright © 2018 Elsevier Ltd. All rights reserved.

Photoresponses of the purple nonsulfur bacteria Rhodospirillum centenum and Rhodobacter sphaeroides.

OpenAIRE

Sackett, M J; Armitage, J P; Sherwood, E E; Pitta, T P

1997-01-01

We have measured the photoresponse of two purple nonsulfur bacteria, Rhodobacter sphaeroides and Rhodospirillum centenum, under defined conditions in a light beam propagating at 90 degrees to the optical axis of the microscope. This beam presented cells with a steep gradient of intensity perpendicular to the direction of propagation and a shallow gradient in the direction of light propagation. R. centenum, a species that reverses to change direction, accumulated in the light beam, as expected...

Efficient analysis of macromolecular rotational diffusion from heteronuclear relaxation data

International Nuclear Information System (INIS)

Dosset, Patrice; Hus, Jean-Christophe; Blackledge, Martin; Marion, Dominique

2000-01-01

A novel program has been developed for the interpretation of 15 N relaxation rates in terms of macromolecular anisotropic rotational diffusion. The program is based on a highly efficient simulated annealing/minimization algorithm, designed specifically to search the parametric space described by the isotropic, axially symmetric and fully anisotropic rotational diffusion tensor models. The high efficiency of this algorithm allows extensive noise-based Monte Carlo error analysis. Relevant statistical tests are systematically applied to provide confidence limits for the proposed tensorial models. The program is illustrated here using the example of the cytochrome c' from Rhodobacter capsulatus, a four-helix bundle heme protein, for which data at three different field strengths were independently analysed and compared

Stoichiometry of ATP hydrolysis and chlorophyllide formation of dark-operative protochlorophyllide oxidoreductase from Rhodobacter capsulatus

Energy Technology Data Exchange (ETDEWEB)

Nomata, Jiro [Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601 (Japan); Terauchi, Kazuki [Department of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, 525-8577 (Japan); Fujita, Yuichi, E-mail: fujita@agr.nagoya-u.ac.jp [Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601 (Japan)

2016-02-12

Dark-operative protochlorophyllide (Pchlide) oxidoreductase (DPOR) is a nitrogenase-like enzyme catalyzing a reduction of the C17 = C18 double bond of Pchlide to form chlorophyllide a (Chlide) in bacteriochlorophyll biosynthesis. DPOR consists of an ATP-dependent reductase component, L-protein (a BchL dimer), and a catalytic component, NB-protein (a BchN–BchB heterotetramer). The L-protein transfers electrons to the NB-protein to reduce Pchlide, which is coupled with ATP hydrolysis. Here we determined the stoichiometry of ATP hydrolysis and the Chlide formation of DPOR. The minimal ratio of ATP to Chlide (ATP/2e{sup –}) was 4, which coincides with that of nitrogenase. The ratio increases with increasing molar ratio of L-protein to NB-protein. This profile differs from that of nitrogenase. These results suggest that DPOR has a specific intrinsic property, while retaining the common features shared with nitrogenase. - Highlights: • The stoichiometry of nitrogenase-like protochlorophyllide reductase was determined. • The minimal ATP/2e{sup –} ratio was 4, which coincides with that of nitrogenase. • The ATP/2e{sup –} ratio increases with increasing L-protein/NB-protein molar ratio. • DPOR has an intrinsic property, but retains features shared with nitrogenase.

Hydrogen production by co-cultures of Lactobacillus and a photosynthetic bacterium, Rhodobacter sphaeroides RV

Energy Technology Data Exchange (ETDEWEB)

Asada, Yasuo; Ishimi, Katsuhiro [Department of General Education, College of Science and Technology, Nihon University, Narashinodai, Chiba 274-8501 (Japan); Tokumoto, Masaru; Aihara, Yasuyuki; Oku, Masayo; Kohno, Hideki [Department of Applied Molecular Chemistry, College of Industrial Technology, Nihon University, Izumi-cho, Chiba 275-8575 (Japan); Wakayama, Tatsuki; Miyake, Jun [Research Institute for Cell Engineering, National Institute of Advanced Industrial Science and Technology, Nakoji, Amagasaki, Hyogo 661-0974 (Japan); Tomiyama, Masamitsu [Genetic Diversity Department, National Institute of Agrobiological Science, Tsukuba, Ibaraki 305-8602 (Japan)

2006-09-15

Hydrogen production with glucose by using co-immobilized cultures of a lactic acid bacterium, Lactobacillus delbrueckii NBRC13953, and a photosynthetic bacterium, Rhodobacter sphaeroides RV, in agar gels was studied. Glucose was converted to hydrogen gas in a yield of 7.1mol of hydrogen per mole of glucose at a maximum under illuminated conditions. (author)

Photodynamics of the small BLUF protein BlrB from Rhodobacter sphaeroides.

Science.gov (United States)

Zirak, P; Penzkofer, A; Schiereis, T; Hegemann, P; Jung, A; Schlichting, I

2006-06-01

The BLUF protein BlrB from the non-sulphur anoxyphototrophic purple bacterium Rhodobacter sphaeroides is characterized by absorption and emission spectroscopy. BlrB expressed from E. coli binding FAD, FMN, and riboflavin (called BrlB(I)) and recombinant BlrB containing only FAD (called BlrB(II)) are investigated. The dark-adapted proteins exist in two different receptor conformations (receptor states) with different sub-nanosecond fluorescence lifetimes (BLUF(r,f) and BLUF(r,sl)). Some of the flavin-cofactor (ca. 8%) is unbound in thermodynamic equilibrium with the bound cofactor. The two receptor conformations are transformed to putative signalling states (BLUF(s,f) and BLUF(s,sl)) of decreased fluorescence efficiency and shortened fluorescence lifetime by blue-light excitation. In the dark at room temperature both signalling states recover back to the initial receptor states with a time constant of about 2s. Quantum yields of signalling state formation of about 90% for BlrB(II) and about 40% for BlrB(I) were determined by intensity dependent transmission measurements. Extended blue-light excitation causes unbound flavin degradation (formation of lumichrome and lumiflavin-derivatives) and bound cofactor conversion to the semiquinone form. The flavin-semiquinone further reduces and the reduced flavin re-oxidizes back in the dark. A photo-dynamics scheme is presented and relevant quantum efficiencies and time constants are determined.

Identification of the chlE gene encoding oxygen-independent Mg-protoporphyrin IX monomethyl ester cyclase in cyanobacteria.

Science.gov (United States)

Yamanashi, Kaori; Minamizaki, Kei; Fujita, Yuichi

2015-08-07

The fifth ring (E-ring) of chlorophyll (Chl) a is produced by Mg-protoporphyrin IX monomethyl ester (MPE) cyclase. There are two evolutionarily unrelated MPE cyclases: oxygen-independent (BchE) and oxygen-dependent (ChlA/AcsF) MPE cyclases. Although ChlA is the sole MPE cyclase in Synechocystis PCC 6803, it is yet unclear whether BchE exists in cyanobacteria. A BLAST search suggests that only few cyanobacteria possess bchE. Here, we report that two bchE candidate genes from Cyanothece strains PCC 7425 and PCC 7822 restore the photosynthetic growth and bacteriochlorophyll production in a bchE-lacking mutant of Rhodobacter capsulatus. We termed these cyanobacterial bchE orthologs "chlE." Copyright © 2015 Elsevier Inc. All rights reserved.

Study of the selenite reduction in Rhodobacter sphaeroides f. sp. denitrificans

International Nuclear Information System (INIS)

Bernier-Pierru, B.

2006-05-01

Selenium is an essential element for all living organisms at the low level; however it becomes toxic and mutagenic at higher concentrations. The predominant forms of selenium in natural environments are selenate and selenite which are toxic. Bacteria can use several mechanisms of detoxification such as methylation in volatile compounds or reduction in elemental selenium. In this way, our model, Rhodobacter sphaeroides f. sp. denitrificans, is able to reduce selenite into selenium. We have combined biochemical and molecular approaches to better characterize the mechanism and protagonists of this reduction. After studying the physiological response of the bacterium in the presence of selenite, we screened a transposon library in order to isolate mutants with a weakened reduction ability. Two of these selected mutants are affected in genes involved in the molybdenum cofactor synthesis, moaA and mogA. Several reductases, the molybdo enzymes, required this cofactor. Furthermore the addition of tungsten, a competitor for the molybdenum, in the culture medium, dramatically reduces the rate of selenite reduction. These results strongly suggest that a molybdo enzyme is involved in one of the selenite reduction pathways. The potential role of different proteins has been investigated, especially for the nitrate reductase, the DMSO reductase and the biotin sulfoxide reductase. We have also selected a mutant affected in the smoM gene which encodes a peri-plasmic component of a TRAP transporter. The phenotype of this mutant suggests the involvement of this transporter in the selenite import. (author)

Grain dust-induced lung inflammation is reduced by Rhodobacter sphaeroides diphosphoryl lipid A.

Science.gov (United States)

Jagielo, P J; Quinn, T J; Qureshi, N; Schwartz, D A

1998-01-01

To further determine the importance of endotoxin in grain dust-induced inflammation of the lower respiratory tract, we evaluated the efficacy of pentaacylated diphosphoryl lipid A derived from the lipopolysaccharide of Rhodobacter sphaeroides (RsDPLA) as a partial agonist of grain dust-induced airway inflammation. RsDPLA is a relatively inactive compound compared with lipid A derived from Escherichia coli (LPS) and has been demonstrated to act as a partial agonist of LPS-induced inflammation. To assess the potential stimulatory effect of RsDPLA in relation to LPS, we incubated THP-1 cells with RsDPLA (0.001-100 micrograms/ml), LPS (0.02 microgram endotoxin activity/ml), or corn dust extract (CDE; 0.02 microgram endotoxin activity/ml). Incubation with RsDPLA revealed a tumor necrosis factor (TNF)-alpha stimulatory effect at 100 micrograms/ml. In contrast, incubation with LPS or CDE resulted in TNF-alpha release at 0.02 microgram/ml. Pretreatment of THP-1 cells with varying concentrations of RsDPLA before incubation with LPS or CDE (0.02 microgram endotoxin activity/ml) resulted in a dose-dependent reduction in the LPS- or CDE-induced release of TNF-alpha with concentrations of RsDPLA of up to 10 micrograms/ml but not at 100 micrograms/ml. To further understand the role of endotoxin in grain dust-induced airway inflammation, we utilized the unique LPS inhibitory property of RsDPLA to determine the inflammatory response to inhaled CDE in mice in the presence of RsDPLA. Ten micrograms of RsDPLA intratracheally did not cause a significant inflammatory response compared with intratracheal saline. However, pretreatment of mice with 10 micrograms of RsDPLA intratracheally before exposure to CDE (5.4 and 0.2 micrograms/m3) or LPS (7.2 and 0.28 micrograms/m3) resulted in significant reductions in the lung lavage concentrations of total cells, neutrophils, and specific proinflammatory cytokines compared with mice pretreated with sterile saline. These results confirm the LPS

Controlling light-use by Rhodobacter capsulatus continuous cultures in a flat-panel photobioreactor

NARCIS (Netherlands)

Hoekema, S.; Douma, R.D.; Janssen, M.G.J.; Tramper, J.; Wijffels, R.H.

2006-01-01

The main bottleneck in scale-up of phototrophic fermentation is the low efficiency of light energy conversion to the desired product, which is caused by an excessive dissipation of light energy to heat. The photoheterotrophic formation of hydrogen from acetate and light energy by the microorganism

Complete genome sequence of the photosynthetic purple nonsulfur bacterium Rhodobacter capsulatus SB 1003

Czech Academy of Sciences Publication Activity Database

Strnad, Hynek; Lapidus, A.; Pačes, Jan; Ulbrich, P.; Vlček, Čestmír; Pačes, Václav; Haselkorn, R.

2010-01-01

Roč. 192, č. 13 (2010), s. 3545-3546 ISSN 0021-9193 R&D Projects: GA MŠk 1M0520 Institutional research plan: CEZ:AV0Z50520514 Keywords : transfer-RNA genes * identification * annotation Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 3.726, year: 2010

DNA sequence analysis of the photosynthesis region of Rhodobacter sphaeroides 2.4.1T

OpenAIRE

Choudhary, M.; Kaplan, Samuel

2000-01-01

This paper describes the DNA sequence of the photosynthesis region of Rhodobacter sphaeroides 2.4.1T. The photosynthesis gene cluster is located within a ~73 kb AseI genomic DNA fragment containing the puf, puhA, cycA and puc operons. A total of 65 open reading frames (ORFs) have been identified, of which 61 showed significant similarity to genes/proteins of other organisms while only four did not reveal any significant sequence similarity to any gene/protein sequences in the database. The da...

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

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

Redox thermodynamics of the native and alkaline forms of eukaryotic and bacterial class I cytochromes c.

Science.gov (United States)

Battistuzzi, G; Borsari, M; Sola, M; Francia, F

1997-12-23

The reduction potentials of beef heart cytochrome c and cytochromes c2 from Rhodopseudomonas palustris, Rhodobacter sphaeroides, and Rhodobacter capsulatus were measured through direct electrochemistry at a surface-modified gold electrode as a function of temperature in nonisothermal experiments carried out at neutral and alkaline pH values. The thermodynamic parameters for protein reduction (DeltaS degrees rc and DeltaH degrees rc) were determined for the native and alkaline conformers. Enthalpy and entropy terms underlying species-dependent differences in E degrees and pH- and temperature-induced E degrees changes for a given cytochrome were analyzed. The difference of about +0.1 V in E degrees between cytochromes c2 and the eukaryotic species can be separated into an enthalpic term (-DeltaDeltaH degrees rc/F) of +0.130 V and an entropic term (TDeltaDeltaS degrees rc/F) of -0.040 V. Hence, the higher potential of the bacterial species appears to be determined entirely by a greater enthalpic stabilization of the reduced state. Analogously, the much lower potential of the alkaline conformer(s) as compared to the native species is by far enthalpic in origin for both protein families, and is largely determined by the substitution of Met for Lys in axial heme ligation. Instead, the biphasic E degrees /temperature profile for the native cytochromes is due to a difference in reduction entropy between the conformers at low and high temperatures. Temperature-dependent 1H NMR experiments suggest that the temperature-induced transition also involves a change in orientation of the axial methionine ligand with respect to the heme plane.

Direct Visualization of Exciton Reequilibration in the LH1 and LH2 Complexes of Rhodobacter sphaeroides by Multipulse Spectroscopy

NARCIS (Netherlands)

Cohen Stuart, T.A.; Vengris, M.; Novoderezhkin, V.I.; Cogdell, R.J.; Hunter, C.N.; van Grondelle, R.

2011-01-01

The dynamics of the excited states of the light-harvesting complexes LH1 and LH2 of Rhodobacter sphaeroides are governed, mainly, by the excitonic nature of these ring-systems. In a pump-dump-probe experiment, the first pulse promotes LH1 or LH2 to its excited state and the second pulse dumps a

Atomistic simulations indicate cardiolipin to have an integral role in the structure of the cytochrome bc(1) complex

DEFF Research Database (Denmark)

Poyry, S.; Cramariuc, O.; Postila, P. A.

2013-01-01

by both ensuring the structural integrity of the protein complex and also by taking part in the proton uptake. Yet, the atom-scale understanding of these highly charged four-tail lipids in the cyt bc(1) function has remained quite unclear. We consider this issue through atomistic molecular dynamics...... the description of the role of the surrounding lipid environment: in addition to the specific CL-protein interactions, we observe the protein domains on the positive side of the membrane to settle against the lipids. Altogether, the simulations discussed in this article provide novel views into the dynamics...... simulations that are applied to the entire cyt bc(1) dimer of the purple photosynthetic bacterium Rhodobacter capsulatus embedded in a lipid bilayer. We find CLs to spontaneously diffuse to the dimer interface to the immediate vicinity of the higher potential heme b groups of the complex's catalytic Q...

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 ...

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 electrostatic environment of its cofactors and highlights the possible long-range electrostatic effects.

Characterization of D-tagatose-3-epimerase from Rhodobacter sphaeroides that converts D-fructose into D-psicose.

Science.gov (United States)

Zhang, Longtao; Mu, Wanmeng; Jiang, Bo; Zhang, Tao

2009-06-01

A non-characterized gene, previously proposed as the D-tagatose-3-epimerase gene from Rhodobacter sphaeroides, was cloned and expressed in Escherichia coli. Its molecular mass was estimated to be 64 kDa with two identical subunits. The enzyme specificity was highest with D-fructose and decreased for other substrates in the order: D-tagatose, D-psicose, D-ribulose, D-xylulose and D-sorbose. Its activity was maximal at pH 9 and 40 degrees C while being enhanced by Mn(2+). At pH 9 and 40 degrees C, 118 g D-psicose l(-1) was produced from 700 g D-fructose l(-1) after 3 h.

Ammonium and methylammonium transport in Rhodobacter sphaeroides

International Nuclear Information System (INIS)

Cordts, M.L.; Gibson, J.

1987-01-01

Rhodobacter spheroides maintained intracellular ammonium pools of 1.1 to 2.6 mM during growth in several fixed nitrogen sources as well as during diazotrophic growth. Addition of 0.15 mM NH 4 + to washed, nitrogen-free cell suspensions was followed by linear uptake of NH 4 + from the medium and transient formation of intracellular pools of 0.9 to 1.5 mM NH 4 + . Transport of NH 4 + was shown to be independent of assimilation by glutamine synthetase because intracellular pools of over 1 mM represented NH 4 + concentration gradients of at least 100-fold across the cytoplasmic membrane. Ammonium pools of over 1 mM were also found in non-growing cell suspensions in nitrogen-free medium after glutamine synthetase was inhibited with methionine sulfoximine. In NH 4 + -free cell suspensions, methylammonium ( 14 CH 3 NH 3 + ) was taken up rapidly, and intracellular concentrations of 0.4 to 0.5 mM were maintained. The 14 CN 3 NH 3 + pool was not affected by methionine sulfoximine. Unlike NH 4 + uptake, 14 CH 3 NH 3 + uptake in nitrogen-free cell suspensions was repressed by growth in NH 4 + . These results suggest that R. sphaeroides may produce an NH 4 + -specific transport system in addition to the NH 4 + / 14 CH 3 NH 3 + transporter. This second transporter is able to produce normal-size NH 4 + pools but has very little affinity for 14 CH 3 NH 3 + and is not repressed by growth in high concentrations of NH 4 +

Transient grating spectroscopy in photosynthetic purple bacteria Rhodobacter sphaeroides 2.4.1

Energy Technology Data Exchange (ETDEWEB)

Sugisaki, Mitsuru, E-mail: mitsuru@sci.osaka-cu.ac.j [CREST-JST and Graduate School of Science, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi, Osaka 558-8585 (Japan); Fujiwara, Masazumi; Fujii, Ritsuko [CREST-JST and Graduate School of Science, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi, Osaka 558-8585 (Japan); Nakagawa, Katsunori; Nango, Mamoru [CREST-JST and Graduate School of Engineering, Nagoya Institute of Technology, Gokiso, Showa, Nagoya 466-8555 (Japan); Cogdell, Richard J. [Glasgow Biomedical Research Centre, IBLS, University of Glasgow, 126 University Place, Glasgow G12 8TA, Scotland (United Kingdom); Hashimoto, Hideki [CREST-JST and Graduate School of Science, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi, Osaka 558-8585 (Japan)

2009-12-15

The vibronic coherence of photosynthetic pigment-protein complexes has been investigated by means of transient grating spectroscopy using sub 20 fs optical pulses. In the present work, we focus our attention on the LH2 antenna complexes from Rhodobacter sphaeroides 2.4.1 because the information about their structure investigated by the electron and atomic force microscopy is available and the electric levels of pigments are well resolved, resulting in clear absorption spectrum. The vibronic coherent oscillations with a period of a few tens of femtoseconds have been clearly observed. We found that the temporal change of the coherent oscillations reflects the vibrational relaxation in the ground state. Calculations based on the Brownian oscillator model were performed under the impulsive excitation limit. The spectral density has been determined from the Raman measurement of spheroidene. Good agreement between the calculation and the experimental results has been achieved in the linear absorption spectrum and transient grating signal, which strongly supports the validity of our model.

Timescales of Coherent Dynamics in the Light Harvesting Complex 2 (LH2) of Rhodobacter sphaeroides.

Science.gov (United States)

Fidler, Andrew F; Singh, Ved P; Long, Phillip D; Dahlberg, Peter D; Engel, Gregory S

2013-05-02

The initial dynamics of energy transfer in the light harvesting complex 2 from Rhodobacter sphaeroides were investigated with polarization controlled two-dimensional spectroscopy. This method allows only the coherent electronic motions to be observed revealing the timescale of dephasing among the excited states. We observe persistent coherence among all states and assign ensemble dephasing rates for the various coherences. A simple model is utilized to connect the spectroscopic transitions to the molecular structure, allowing us to distinguish coherences between the two rings of chromophores and coherences within the rings. We also compare dephasing rates between excited states to dephasing rates between the ground and excited states, revealing that the coherences between excited states dephase on a slower timescale than coherences between the ground and excited states.

Identification of the upper exciton component of the B850 bacteriochlorophylls of the LH2 antenna complex, using a B800-free mutant of Rhodobacter sphaeroides.

NARCIS (Netherlands)

Koolhaas, M.H.C.; Frese, R.N.; Fowler, G.J.S.; Bibby, T.S.; Georgakopoulou, S.; van der Zwan, G.; Hunter, C.N.; van Grondelle, R.

1998-01-01

In this paper, we report the circular dichroism (CD) spectra of two types of LH2 -only mutants of Rhodobacter sphaeroides. In the first, only the wild type LH2 is present, while in the second, the B800 binding site of LH2 has been either destabilized or removed. For the first time, we have

Bacterial Survival under Extreme UV Radiation: A Comparative Proteomics Study of Rhodobacter sp., Isolated from High Altitude Wetlands in Chile

Directory of Open Access Journals (Sweden)

Vilma Pérez

2017-06-01

Full Text Available Salar de Huasco, defined as a polyextreme environment, is a high altitude saline wetland in the Chilean Altiplano (3800 m.a.s.l., permanently exposed to the highest solar radiation doses registered in the world. We present here the first comparative proteomics study of a photoheterotrophic bacterium, Rhodobacter sp., isolated from this remote and hostile habitat. We developed an innovative experimental approach using different sources of radiation (in situ sunlight and UVB lamps, cut-off filters (Mylar, Lee filters and a high-throughput, label-free quantitative proteomics method to comprehensively analyze the effect of seven spectral bands on protein regulation. A hierarchical cluster analysis of 40 common proteins revealed that all conditions containing the most damaging UVB radiation induced similar pattern of protein regulation compared with UVA and visible light spectral bands. Moreover, it appeared that the cellular adaptation of Rhodobacter sp. to osmotic stress encountered in the hypersaline environment from which it was originally isolated, might further a higher resistance to damaging UV radiation. Indeed, proteins involved in the synthesis and transport of key osmoprotectants, such as glycine betaine and inositol, were found in very high abundance under UV radiation compared to the dark control, suggesting the function of osmolytes as efficient reactive oxygen scavengers. Our study also revealed a RecA-independent response and a tightly regulated network of protein quality control involving proteases and chaperones to selectively degrade misfolded and/or damaged proteins.

The role of Cercospora zeae-maydis homologs of Rhodobacter sphaeroides 1O2-resistance genes in resistance to the photoactivated toxin cercosporin.

Science.gov (United States)

Beseli, Aydin; Goulart da Silva, Marilia; Daub, Margaret E

2015-01-01

The photosynthetic bacterium Rhodobacter sphaeroides and plant pathogenic fungus Cercospora nicotianae have been used as models for understanding resistance to singlet oxygen ((1)O(2)), a highly toxic reactive oxygen species. In Rhodobacter and Cercospora, (1)O(2) is derived, respectively, from photosynthesis and from the (1)O(2)-generating toxin cercosporin which the fungus produces to parasitize plants. We identified common genes recovered in transcriptome studies of putative (1)O(2)-resistance genes in these two systems, suggesting common (1)O(2)-resistance mechanisms. To determine if the Cercospora homologs of R. sphaeroides (1)O(2)-resistance genes are involved in resistance to cercosporin, we expressed the genes in the cercosporin-sensitive fungus Neurospora crassa and assayed for increases in cercosporin resistance. Neurospora crassa transformants expressing genes encoding aldo/keto reductase, succinyl-CoA ligase, O-acetylhomoserine (thiol) lyase, peptide methionine sulphoxide reductase and glutathione S-transferase did not have elevated levels of cercosporin resistance. Several transformants expressing aldehyde dehydrogenase were significantly more resistant to cercosporin. Expression of the transgene and enzyme activity did not correlate with resistance, however. We conclude that although the genes tested in this study are important in (1)O(2) resistance in R. sphaeroides, their Cercospora homologs are not involved in resistance to (1)O(2) generated from cercosporin. © FEMS 2014. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Ammonium and methylammonium transport in Rhodobacter sphaeroides

Energy Technology Data Exchange (ETDEWEB)

Cordts, M.L.; Gibson, J.

1987-04-01

Rhodobacter spheroides maintained intracellular ammonium pools of 1.1 to 2.6 mM during growth in several fixed nitrogen sources as well as during diazotrophic growth. Addition of 0.15 mM NH/sub 4//sup +/ to washed, nitrogen-free cell suspensions was followed by linear uptake of NH/sub 4//sup +/ from the medium and transient formation of intracellular pools of 0.9 to 1.5 mM NH/sub 4//sup +/. Transport of NH/sub 4//sup +/ was shown to be independent of assimilation by glutamine synthetase because intracellular pools of over 1 mM represented NH/sub 4//sup +/ concentration gradients of at least 100-fold across the cytoplasmic membrane. Ammonium pools of over 1 mM were also found in non-growing cell suspensions in nitrogen-free medium after glutamine synthetase was inhibited with methionine sulfoximine. In NH/sub 4//sup +/-free cell suspensions, methylammonium (/sup 14/CH/sub 3/NH/sub 3//sup +/) was taken up rapidly, and intracellular concentrations of 0.4 to 0.5 mM were maintained. The /sup 14/CN/sub 3/NH/sub 3//sup +/ pool was not affected by methionine sulfoximine. Unlike NH/sub 4//sup +/ uptake, /sup 14/CH/sub 3/NH/sub 3//sup +/ uptake in nitrogen-free cell suspensions was repressed by growth in NH/sub 4//sup +/. These results suggest that R. sphaeroides may produce an NH/sub 4//sup +/-specific transport system in addition to the NH/sub 4//sup +///sup 14/CH/sub 3/NH/sub 3//sup +/ transporter. This second transporter is able to produce normal-size NH/sub 4//sup +/ pools but has very little affinity for /sup 14/CH/sub 3/NH/sub 3//sup +/ and is not repressed by growth in high concentrations of NH/sub 4//sup +/.

Phytoavailability and geospeciation of cadmium in contaminated soil remediated by Rhodobacter sphaeroides.

Science.gov (United States)

Fan, Wenhong; Jia, Yingying; Li, Xiaomin; Jiang, Wei; Lu, Lin

2012-07-01

A microorganism was isolated from oil field injection water and identified as Rhodobacter sphaeroides. It was used for the remediation of simulated cadmium-contaminated soil. The phytoavailability of Cd was investigated through wheat seedling method to determine the efficiency of remediation. It was found that after remediation, the accumulation of Cd in wheat roots and leaves decreased by 67% and 53%, respectively. The Cd speciation in soil was determined with Tessier extraction procedure. It was found that the total Cd content in soil did not change during the experiments, but the geo-speciation of Cd changed remarkably. Among the five fractions, the concentration of exchangeable phases decreased by 27-46% and that of the phases bound to Fe-Mn oxides increased by 22-44%. The decrease of Cd accumulation in wheat showed significant positive correlation with the decrease of exchangeable phases. It could be concluded that the remediation of R. sphaeroides was carried out through the conversion of Cd to more stable forms. The decrease of sulfate concentration in supernatant indicated that the R. sphaeroides consumed sulfate. Copyright © 2012 Elsevier Ltd. All rights reserved.

Effect of pH on optimization of photofermentative hydrogen production by co-culture of Rhodobacter sphaeroides-NMBL-02 and Bacillus firmus-NMBL-03.

Science.gov (United States)

Pandey, A; Dolly, S; Semwal, D; Pandey, A

2017-07-31

Rhodobacter sphaeroides NMBL-02, photosynthetic purple non sulfur (PNS) bacteria and associated Bacillus firmus NMBL-03 were isolated from water sample collected from 15-20 inches beneath the surface of ponds from Northern region of India in modified Sistrom's media (120 ml) containing 3 g/L malate and 1.2 g/L ammonium sulfate. The isolation was done in air tight serum bottles (120 ml) under tungsten bulb (1.8 kLux light intensity) at 30 oC ± 2 oC. The PNS and heterotrophic bacteria associated with the culture was purified by clonal selection method and characterized by 16S rDNA sequencing. The PNS isolate was identified as Rhodobacter sphaeroides NMBL-02 (ID: 1467407, Accession BANKIT: JN256030) and associated heterotroph as Bacillus firmus NMBL-03 (Gene Bank Accession no.: JN 256029). The effect of initial medium pH on optimization of hydrogen production was investigated in batch process. The maximum hydrogen potential and hydrogen production rate was 2310 ± 55 ml/L and 4.75 ml/L culture/h respectively using glutamate (1.7 mmol/L) as nitrogen source and malate (22.38 mmol/L) as carbon source with 76.39% malate conversion efficiency at initial medium pH 5.0. This co-culture has the ability to produce significant amount of hydrogen in the pH range of 5.0 to 10.0 with 76.39% to 35.71% malate conversion respectively.

Mathematical model for the analytical signal of an herbicide sensor based on the reaction centre of Rhodobacter sphaeroides.

Science.gov (United States)

Andreu, Yolanda; Baldini, Francesco; Giannetti, Ambra; Mencaglia, Andrea

2005-01-30

This paper introduces a mathematical model which makes it possible both to determine the concentration of photosynthetic herbicides and to obtain a quantitative parameter in order to compare their activity using a previously described sensing system. The working principle involves the changes in absorption properties at 860nm of the reaction centre (RC) isolated from the bacteria Rhodobacter sphaeroides when photosynthetic herbicides are present. The method has been used for the determination and activity comparison of five photosynthetic herbicides: diuron, atrazine, terbutryn, terbuthylazine and simazine. Detection limits obtained were 2.2, 0.75, 0.046, 0.25, and 1.4muM, respectively. The resulting order for the different herbicides according to their action on RC was: terbutryn > terbuthylazine > atrazine > simazine > diuron.

Nitrate-Dependent Degradation of Acetone by Alicycliphilus and Paracoccus Strains and Comparison of Acetone Carboxylase Enzymes ▿

Science.gov (United States)

Dullius, Carlos Henrique; Chen, Ching-Yuan; Schink, Bernhard

2011-01-01

A novel acetone-degrading, nitrate-reducing bacterium, strain KN Bun08, was isolated from an enrichment culture with butanone and nitrate as the sole sources of carbon and energy. The cells were motile short rods, 0.5 to 1 by 1 to 2 μm in size, which gave Gram-positive staining results in the exponential growth phase and Gram-negative staining results in the stationary-growth phase. Based on 16S rRNA gene sequence analysis, the isolate was assigned to the genus Alicycliphilus. Besides butanone and acetone, the strain used numerous fatty acids as substrates. An ATP-dependent acetone-carboxylating enzyme was enriched from cell extracts of this bacterium and of Alicycliphilus denitrificans K601T by two subsequent DEAE Sepharose column procedures. For comparison, acetone carboxylases were enriched from two additional nitrate-reducing bacterial species, Paracoccus denitrificans and P. pantotrophus. The products of the carboxylase reaction were acetoacetate and AMP rather than ADP. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis of cell extracts and of the various enzyme preparations revealed bands corresponding to molecular masses of 85, 78, and 20 kDa, suggesting similarities to the acetone carboxylase enzymes described in detail for the aerobic bacterium Xanthobacter autotrophicus strain Py2 (85.3, 78.3, and 19.6 kDa) and the phototrophic bacterium Rhodobacter capsulatus. Protein bands were excised and compared by mass spectrometry with those of acetone carboxylases of aerobic bacteria. The results document the finding that the nitrate-reducing bacteria studied here use acetone-carboxylating enzymes similar to those of aerobic and phototrophic bacteria. PMID:21841031

Improved hydrogen production by uptake hydrogenase deficient mutant strain of Rhodobacter sphaeroides O.U.001

Energy Technology Data Exchange (ETDEWEB)

Kars, Goekhan; Guenduez, Ufuk; Yuecel, Meral [Department of Biological Sciences, Middle East Technical University, 06531 Ankara (Turkey); Rakhely, Gabor; Kovacs, Kornel L. [Institute of Biophysics, Biological Research Centre, Hungarian Academy of Sciences, Szeged (Hungary); Eroglu, Inci [Department of Chemical Engineering, Middle East Technical University, 06531 Ankara (Turkey)

2008-06-15

Rhodobacter sphaeroides O.U.001 is a purple non-sulfur bacterium producing hydrogen under photoheterotrophic conditions. Hydrogen is produced by Mo-nitrogenase enzyme and substantial amount of H{sub 2} is reoxidized by a membrane-bound uptake hydrogenase in the wild type strain. To improve the hydrogen producing capacity of the cells, a suicide vector containing a gentamicin cassette in the hupSL genes was introduced into R. sphaeroiodes O.U.001 and the uptake hydrogenase genes were destroyed by site directed mutagenesis. The correct integration of the construct was confirmed by uptake hydrogenase activity measurement, PCR and subsequent sequence analysis. The wild type and the mutant cells showed similar growth patterns but the total volume of hydrogen gas evolved by the mutant was 20% higher than that of the wild type strain. This result demonstrated that the hydrogen produced by the nitrogenase was not consumed by uptake hydrogenase leading to higher hydrogen production. (author)

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.

Bioremediation of petroleum hydrocarbon contaminated soil by Rhodobacter sphaeroides biofertilizer and plants.

Science.gov (United States)

Jiao, Haihua; Luo, Jinxue; Zhang, Yiming; Xu, Shengjun; Bai, Zhihui; Huang, Zhanbin

2015-09-01

Bio-augmentation is a promising technique for remediation of polluted soils. This study aimed to evaluate the bio-augmentation effect of Rhodobacter sphaeroides biofertilizer (RBF) on the bioremediation of total petroleum hydrocarbons (TPH) contaminated soil. A greenhouse pot experiment was conducted over a period of 120 days, three methods for enhancing bio-augmentation were tested on TPH contaminated soils, including single addition RBF, planting, and combining of RBF and three crop species, such as wheat (W), cabbage (C) and spinach (S), respectively. The results demonstrated that the best removal of TPH from contaminated soil in the RBF bio-augmentation rhizosphere soils was found to be 46.2%, 65.4%, 67.5% for W+RBF, C+RBF, S+RBF rhizosphere soils respectively. RBF supply impacted on the microbial community diversity (phospholipid fatty acids, PLFA) and the activity of soil enzymes, such as dehydrogenase (DH), alkaline phosphatase (AP) and urease (UR). There were significant difference among the soil only containing crude oil (CK), W, C and S rhizosphere soils and RBF bio-augmentation soils. Moreover, the changes were significantly distinct depended on crops species. It was concluded that the RBF is a valuable material for improving effect of remediation of TPH polluted soils.

Trends of bio-hydrogen research and development in Europe. Report for the Research Institute of Innovative Technology for the Earth (RITE), Tokyo, Japan

Energy Technology Data Exchange (ETDEWEB)

Huesing, B.

1997-03-01

Research into applied aspects of biological hydrogen production is carried out on a much lower level in Europe than basic hydrogenase research. However, the screening for good H{sub 2} producers, their cultivation, and the development of optimised culture and bioreactor systems has never been a strength in Europe. Although there are a few good groups in Europe major contributions in this field traditionally come from countries outside Europe. However, in the nineties a special application-oriented research subfield has begun to evolve in Europe: the use of genetic enginering to rationally optimise H{sub 2} producing organisms. The most important players who focus on green algae, cyanobacteria, and purple bacteria can be found in Germany, France, and Sweden. In European biohydrogen research, a large and diverse variety of organisms is investigated. Among the organisms most thoroughly studied are Alcaligenes eutrophus, Escherichia coli, Rhodobacter capsulatus, sulfate-reducing bacteria, and methanogenic bacteria. Moreover, a leading position has been obtained with respect to molecular genetics of green algae and cyanobacteria, albeit on a low level. The fact that such a broad range of diverse organisms is studied has advantages and disadvantages. A positive aspect is that the multitude of different approaches had led to several unexpected results which had otherwise been overlooked. On the other hand, an obvious link to biohydrogen production is often lacking. Moreover, there are many 'me-too' approaches and results in which previous findings are only reproduced for another organism as well. (orig.)

Exploitation of dark fermented effluent of cheese whey by co-culture of Rhodobacter sphaeroides and Bacillus firmus for photo-hydrogen production.

Science.gov (United States)

Pandey, A; Pandey, A

2017-07-31

In this study photo-hydrogen production from cheese whey dark fermentation (DF) effluent by the co-culture of Rhodobacter sphaeroides -NMBL-01 and Bacillus firmus - NMBL-03 has been reported. The effect of pH, initial chemical oxygen demand (COD) and the concentration effect of FeSO4.7H2O on photo-hydrogen production have been investigated. The end products of dark fermentation effluent of cheese whey were mainly comprised of soluble organic acids, i.e. butyric acid and lactic acid. The batch process was carried out under light intensity of 2.5 kLux at 32 ± 2oC without any addition of extra carbon and nitrogen source. The single parameter optimization studies revealed optimum pH 6.5, initial COD 4.71 g/L and supplementation of Fe2+ concentration 100 mg/L. The maximum cumulative hydrogen production and yield were found to be 469 ± 45.8 ml H2/L and 146.56 ± 14.31 ml H2/g COD reduced (67.9% reduction in COD) respectively. The mutual interactions among the process parameters were also investigated by three factorial Box-Behnken design of response surface methodology. The optimized experimental values were found concurrent with the calculated values obtained from the theoretical model.

Phototrophic hydrogen production from glucose by pure and co-cultures of Clostridium butyricum and Rhodobacter sphaeroides

Energy Technology Data Exchange (ETDEWEB)

Fang, Herbert H.P.; Zhu, Heguang; Zhang, Tong [Centre for Environmental Engineering Research, Department of Civil Engineering, University of Hong Kong, Pokfulam Road, Hong Kong (China)

2006-12-15

Phototrophic hydrogen production from glucose by pure and co-cultures of Clostridium butyricum and Rhodobacter sphaeroides was studied in batch experiments. Results showed that in all batches hydrogen was produced after a lag phase of about 10h; pure culture of R. sphaeroides produced hydrogen at rates substantially lower than C. butyricum. In co-culture systems, R. sphaeroides even with cell populations 5.9 times higher still could not compete with C. butyricum for glucose. In co-culture systems, R. sphaeroides syntrophically interacted with C. butyricum, using the acetate and butyrate produced by the latter as substrate for hydrogen production. Hydrogen production was ceased in all batches when the pH was lowered to the level of pH 6.5, resulting from the accumulation of fatty acids. It was also demonstrated in this study that fluorescence in situ hybridization (FISH) was an effective means for the quantification of the relative abundance of individual bacteria in a co-culture system. (author)

Transient absorption study of two-photon excitation mechanism in the LH2 complex from purple bacterium Rhodobacter sphaeroides.

Science.gov (United States)

Stepanenko, Ilya; Kompanetz, Viktor; Makhneva, Zoya; Chekalin, Sergey; Moskalenko, Andrei; Razjivin, Andrei

2012-03-08

The mechanism of two-photon excitation of a peripheral light-harvesting complex LH2 (B800-850) from purple bacterium Rhodobacter sphaeroides was explained on the basis of femtosecond transient absorption data. Fast bleaching of the B850 absorption band was measured under two-photon excitation by 1350 nm femtosecond pulses, showing fast subpicosecond arrival of excitation energy to B850 circular aggregates. Any spectral changes connected with the B800 absorption band of B800-BChl molecules were absent. A similar picture was observed under one-photon excitation of the LH2 complex by 675 nm femtosecond pulses. We believe these effects may be attributed to direct excitation of high-energy excitonic states of a B850 circular aggregate or its vibrational manifold in accordance with the model of Abe [Chem. Phys. 2001, 264, 355-363].

A new nitrilase-producing strain named Rhodobacter sphaeroides LHS-305: biocatalytic characterization and substrate specificity.

Science.gov (United States)

Yang, Chunsheng; Wang, Xuedong; Wei, Dongzhi

2011-12-01

The characteristics of the new nitrilase-producing strain Rhodobacter sphaeroides LHS-305 were investigated. By investigating several parameters influencing nitrilase production, the specific cell activity was ultimately increased from 24.5 to 75.0 μmol g(-1) min(-1), and hereinto, the choice of inducer proved the most important factor. The aromatic nitriles (such as 3-cyanopyridine and benzonitrile) were found to be the most favorable substrates of the nitrilase by analyzing the substrate spectrum. It was speculated that the unsaturated carbon atom attached to the cyano group was crucial for this type of nitrilase. The value of apparent K (m), substrate inhibition constant, and product inhibition constant of the nitrilase against 3-cyanopyridine were 4.5 × 10(-2), 29.2, and 8.6 × 10(-3) mol L(-1), respectively. When applied in nicotinic acid preparation, the nitrilase is able to hydrolyze 200 mmol L(-1) 3-cyanopyridine with 93% conversion rate in 13 h by 6.1 g L(-1) cells (dry cell weight).

Absorption and fluorescence spectroscopic characterization of BLUF domain of AppA from Rhodobacter sphaeroides

Science.gov (United States)

Zirak, P.; Penzkofer, A.; Schiereis, T.; Hegemann, P.; Jung, A.; Schlichting, I.

2005-08-01

The BLUF domain of the transcriptional anti-repressor protein AppA from the non-sulfur anoxyphototrophic purple bacterium Rhodobacter sphaeroides was characterized by absorption and emission spectroscopy. The BLUF domain constructs AppA 148 (consisting of amino-acid residues 1-148) and AppA 126 (amino-acid residues 1-126) are investigated. The cofactor of the investigated domains is found to consist of a mixture of the flavins riboflavin, FMN, and FAD. The dark-adapted domains exist in two different active receptor conformations (receptor states) with different sub-nanosecond fluorescence lifetimes (BLUF r,f and BLUF r,sl) and a small non-interacting conformation (BLUF nc). The active receptor conformations are transformed to putative signalling states (BLUF s,f and BLUF s,sl) of low fluorescence efficiency and picosecond fluorescence lifetime by blue-light excitation (light-adapted domains). In the dark at room temperature both signalling states recover back to the initial receptor states with a time constant of about 17 min. A quantum yield of signalling state formation of about 25% was determined by intensity dependent transmission measurements. A photo-cycle scheme is presented including photo-induced charge transfer complex formation, charge recombination, and protein binding pocket reorganisation.

Absorption and fluorescence spectroscopic characterization of BLUF domain of AppA from Rhodobacter sphaeroides

International Nuclear Information System (INIS)

Zirak, P.; Penzkofer, A.; Schiereis, T.; Hegemann, P.; Jung, A.; Schlichting, I.

2005-01-01

The BLUF domain of the transcriptional anti-repressor protein AppA from the non-sulfur anoxyphototrophic purple bacterium Rhodobacter sphaeroides was characterized by absorption and emission spectroscopy. The BLUF domain constructs AppA 148 (consisting of amino-acid residues 1-148) and AppA 126 (amino-acid residues 1-126) are investigated. The cofactor of the investigated domains is found to consist of a mixture of the flavins riboflavin, FMN, and FAD. The dark-adapted domains exist in two different active receptor conformations (receptor states) with different sub-nanosecond fluorescence lifetimes (BLUF r,f and BLUF r,sl ) and a small non-interacting conformation (BLUF nc ). The active receptor conformations are transformed to putative signalling states (BLUF s,f and BLUF s,sl ) of low fluorescence efficiency and picosecond fluorescence lifetime by blue-light excitation (light-adapted domains). In the dark at room temperature both signalling states recover back to the initial receptor states with a time constant of about 17 min. A quantum yield of signalling state formation of about 25% was determined by intensity dependent transmission measurements. A photo-cycle scheme is presented including photo-induced charge transfer complex formation, charge recombination, and protein binding pocket reorganisation

A novel nitrilase from Rhodobacter sphaeroides LHS-305: cloning, heterologous expression and biochemical characterization.

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Wang, Hualei; Li, Guinan; Li, Mingyang; Wei, Dongzhi; Wang, Xuedong

2014-01-01

In this study, a novel nitrilase gene from Rhodobacter sphaeroides was cloned and overexpressed in Escherichia coli. The open reading frame of the nitrilase gene includes 969 base pairs, which encodes a putative polypeptide of 322 amino acid residues. The molecular weight of the purified native nitrilase was about 560 kDa determined by size exclusion chromatography. This nitrilase showed one single band on SDS-PAGE with a molecular weight of 40 kDa. This suggested that the native nitrilase consisted of 14 subunits with identical size. The optimal pH and temperature of the purified enzyme were 7.0 and 40 °C, respectively. The kinetic parameters V max and K m toward 3-cyanopyridine were 77.5 μmol min(-1) mg(-1) and 73.1 mmol/l, respectively. The enzyme can easily convert aliphatic nitrile and aromatic nitriles to their corresponding acids. Furthermore, this enzyme demonstrated regioselectivity in hydrolysis of aliphatic dinitriles. This specific characteristic makes this nitrilase have a great potential for commercial production of various cyanocarboxylic acids by hydrolyzing readily available dinitriles.

Structural model and excitonic properties of the dimeric RC-LH1-PufX complex from Rhodobacter sphaeroides

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Sener, Melih; Hsin, Jen; Trabuco, Leonardo G.; Villa, Elizabeth; Qian, Pu; Hunter, C. Neil; Schulten, Klaus

2009-01-01

The light-harvesting apparatus of the purple bacterial photosynthetic unit consists of a pool of peripheral light-harvesting complexes that transfer excitation energy to a reaction center (RC) via the surrounding pigment-protein complex LH1. Recent electron microscopy and atomic force microscopy studies have revealed that RC-LH1 units of Rhodobacter (Rba.) sphaeroides form membrane-bending dimeric complexes together with the polypeptide PufX. We present a structural model for these RC-LH1-PufX dimeric complexes constructed using the molecular dynamics flexible fitting method based on an EM density map. The arrangement of the LH1 BChls displays a distortion near the proposed location of the PufX polypeptide. The resulting atomic model for BChl arrays is used to compute the excitonic properties of the dimeric RC-LH1 complex. A comparison is presented between the structural and excitonic features of the S-shaped dimeric BChl array of Rba. sphaeroides and the circular BChl arrangement found in other purple bacteria

Absorption and fluorescence spectroscopic characterization of BLUF domain of AppA from Rhodobacter sphaeroides

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Zirak, P. [Institut II - Experimentelle und Angewandte Physik, Universitaet Regensburg, Universitaetstrasse 31, D-93053 Regensburg (Germany); Penzkofer, A. [Institut II - Experimentelle und Angewandte Physik, Universitaet Regensburg, Universitaetstrasse 31, D-93053 Regensburg (Germany)], E-mail: alfons.penzkofer@physik.uni-regensburg.de; Schiereis, T. [Institut fuer Biologie, Experimentelle Biophysik, Humboldt-Universitaet zu Berlin, Invalidenstrasse 42, D-10115 Berlin (Germany); Hegemann, P. [Institut fuer Biologie, Experimentelle Biophysik, Humboldt-Universitaet zu Berlin, Invalidenstrasse 42, D-10115 Berlin (Germany); Jung, A. [Max-Planck-Institut fuer medizinische Forschung, Abteilung Biomolekulare Mechanismen, Jahnstrasse 29, D-69120 Heidelberg (Germany); Schlichting, I. [Max-Planck-Institut fuer medizinische Forschung, Abteilung Biomolekulare Mechanismen, Jahnstrasse 29, D-69120 Heidelberg (Germany)

2005-08-08

The BLUF domain of the transcriptional anti-repressor protein AppA from the non-sulfur anoxyphototrophic purple bacterium Rhodobacter sphaeroides was characterized by absorption and emission spectroscopy. The BLUF domain constructs AppA{sub 148} (consisting of amino-acid residues 1-148) and AppA{sub 126} (amino-acid residues 1-126) are investigated. The cofactor of the investigated domains is found to consist of a mixture of the flavins riboflavin, FMN, and FAD. The dark-adapted domains exist in two different active receptor conformations (receptor states) with different sub-nanosecond fluorescence lifetimes (BLUF{sub r,f} and BLUF{sub r,sl}) and a small non-interacting conformation (BLUF{sub nc}). The active receptor conformations are transformed to putative signalling states (BLUF{sub s,f} and BLUF{sub s,sl}) of low fluorescence efficiency and picosecond fluorescence lifetime by blue-light excitation (light-adapted domains). In the dark at room temperature both signalling states recover back to the initial receptor states with a time constant of about 17 min. A quantum yield of signalling state formation of about 25% was determined by intensity dependent transmission measurements. A photo-cycle scheme is presented including photo-induced charge transfer complex formation, charge recombination, and protein binding pocket reorganisation.

Role of the Irr protein in the regulation of iron metabolism in Rhodobacter sphaeroides.

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Verena Peuser

Full Text Available In Rhizobia the Irr protein is an important regulator for iron-dependent gene expression. We studied the role of the Irr homolog RSP_3179 in the photosynthetic alpha-proteobacterium Rhodobacter sphaeroides. While Irr had little effect on growth under iron-limiting or non-limiting conditions its deletion resulted in increased resistance to hydrogen peroxide and singlet oxygen. This correlates with an elevated expression of katE for catalase in the Irr mutant compared to the wild type under non-stress conditions. Transcriptome studies revealed that Irr affects the expression of genes for iron metabolism, but also has some influence on genes involved in stress response, citric acid cycle, oxidative phosphorylation, transport, and photosynthesis. Most genes showed higher expression levels in the wild type than in the mutant under normal growth conditions indicating an activator function of Irr. Irr was however not required to activate genes of the iron metabolism in response to iron limitation, which showed even stronger induction in the absence of Irr. This was also true for genes mbfA and ccpA, which were verified as direct targets for Irr. Our results suggest that in R. sphaeroides Irr diminishes the strong induction of genes for iron metabolism under iron starvation.

Crystallization and preliminary crystallographic studies of FoxE from Rhodobacter ferrooxidans SW2, an FeII oxidoreductase involved in photoferrotrophy

International Nuclear Information System (INIS)

Pereira, L.; Saraiva, I. H.; Coelho, R.; Newman, D. K.; Louro, R. O.; Frazão, C.

2012-01-01

Crystals of the R. ferrooxidans SW2 iron oxidoreductase FoxE were obtained and the phase problem was solved by Fe SAD at 2.44 Å resolution. FoxE is a protein encoded by the foxEYZ operon of Rhodobacter ferrooxidans SW2 that is involved in Fe II -based anoxygenic photosynthesis (‘photoferrotrophy’). It is thought to reside in the periplasm, where it stimulates light-dependent Fe II oxidation. It contains 259 residues, including two haem c-binding motifs. As no three-dimensional model is available and there is no structure with a similar sequence, crystals of FoxE were produced. They diffracted to 2.44 Å resolution using synchrotron radiation at the Fe edge. The phase problem was solved by SAD using SHELXC/D/E and the experimental maps confirmed the presence of two haems per molecule

Connectivity of the intracytoplasmic membrane of Rhodobacter sphaeroides: a functional approach.

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Verméglio, André; Lavergne, Jérôme; Rappaport, Fabrice

2016-01-01

The photosynthetic apparatus in the bacterium Rhodobacter sphaeroides is mostly present in intracytoplasmic membrane invaginations. It has long been debated whether these invaginations remain in topological continuity with the cytoplasmic membrane, or form isolated chromatophore vesicles. This issue is revisited here by functional approaches. The ionophore gramicidin was used as a probe of the relative size of the electro-osmotic units in isolated chromatophores, spheroplasts, or intact cells. The decay of the membrane potential was monitored from the electrochromic shift of carotenoids. The half-time of the decay induced by a single channel in intact cells was about 6 ms, thus three orders of magnitude slower than in isolated chromatophores. In spheroplasts obtained by lysis of the cell wall, the single channel decay was still slower (~23 ms) and the sensitivity toward the gramicidin concentration was enhanced 1,000-fold with respect to isolated chromatophores. These results indicate that the area of the functional membrane in cells or spheroplasts is about three orders of magnitude larger than that of isolated chromatophores. Intracytoplasmic vesicles, if present, could contribute to at most 10% of the photosynthetic apparatus in intact cells of Rba. sphaeroides. Similar conclusions were obtained from the effect of a ∆pH-induced diffusion potential in intact cells. This caused a large electrochromic response of carotenoids, of similar amplitude as the light-induced change, indicating that most of the system is sensitive to a pH change of the external medium. A single internal membrane and periplasmic space may offer significant advantages concerning renewal of the photosynthetic apparatus and reallocation of the components shared with other bioenergetic pathways.

Direct visualization of exciton reequilibration in the LH1 and LH2 complexes of Rhodobacter sphaeroides by multipulse spectroscopy.

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Cohen Stuart, Thomas A; Vengris, Mikas; Novoderezhkin, Vladimir I; Cogdell, Richard J; Hunter, C Neil; van Grondelle, Rienk

2011-05-04

The dynamics of the excited states of the light-harvesting complexes LH1 and LH2 of Rhodobacter sphaeroides are governed, mainly, by the excitonic nature of these ring-systems. In a pump-dump-probe experiment, the first pulse promotes LH1 or LH2 to its excited state and the second pulse dumps a portion of the excited state. By selective dumping, we can disentangle the dynamics normally hidden in the excited-state manifold. We find that by using this multiple-excitation technique we can visualize a 400-fs reequilibration reflecting relaxation between the two lowest exciton states that cannot be directly explored by conventional pump-probe. An oscillatory feature is observed within the exciton reequilibration, which is attributed to a coherent motion of a vibrational wavepacket with a period of ∼150 fs. Our disordered exciton model allows a quantitative interpretation of the observed reequilibration processes occurring in these antennas. Copyright © 2011 Biophysical Society. Published by Elsevier Inc. All rights reserved.

RNA degradation in Archaea and Gram-negative bacteria different from Escherichia coli.

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Evguenieva-Hackenberg, Elena; Klug, Gabriele

2009-01-01

Exoribonucleolytic and endoribonucleolytic activities are important for controlled degradation of RNA and contribute to the regulation of gene expression at the posttranscriptional level by influencing the half-lives of specific messenger RNAs. The RNA half-lives are determined by the characteristics of the RNA substrates and by the availability and the properties of the involved proteins-ribonucleases and assisting polypeptides. Much is known about RNA degradation in Eukarya and Bacteria, but there is limited information about RNA-degrading enzymes and RNA destabilizing or stabilizing elements in the domain of the Archaea. The recent progress in the understanding of the structure and function of the archaeal exosome, a protein complex with RNA-degrading and RNA-tailing capabilities, has given some first insights into the mechanisms of RNA degradation in the third domain of life and into the evolution of RNA-degrading enzymes. Moreover, other archaeal RNases with degrading potential have been described and a new mechanism for protection of the 5'-end of RNA in Archaea was discovered. Here, we summarize the current knowledge on RNA degradation in the Archaea. Additionally, RNA degradation mechanisms in Rhodobacter capsulatus and Pseudomonas syringae are compared to those in the major model organism for Gram-negatives, Escherichia coli, which dominates our view on RNA degradation in Bacteria.

Engineering of a calcium-ion binding site into the RC-LH1-PufX complex of Rhodobacter sphaeroides to enable ion-dependent spectral red-shifting.

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Swainsbury, David J K; Martin, Elizabeth C; Vasilev, Cvetelin; Parkes-Loach, Pamela S; Loach, Paul A; Neil Hunter, C

2017-11-01

The reaction centre-light harvesting 1 (RC-LH1) complex of Thermochromatium (Tch.) tepidum has a unique calcium-ion binding site that enhances thermal stability and red-shifts the absorption of LH1 from 880nm to 915nm in the presence of calcium-ions. The LH1 antenna of mesophilic species of phototrophic bacteria such as Rhodobacter (Rba.) sphaeroides does not possess such properties. We have engineered calcium-ion binding into the LH1 antenna of Rba. sphaeroides by progressively modifying the native LH1 polypeptides with sequences from Tch. tepidum. We show that acquisition of the C-terminal domains from LH1 α and β of Tch. tepidum is sufficient to activate calcium-ion binding and the extent of red-shifting increases with the proportion of Tch. tepidum sequence incorporated. However, full exchange of the LH1 polypeptides with those of Tch. tepidum results in misassembled core complexes. Isolated α and β polypeptides from our most successful mutant were reconstituted in vitro with BChl a to form an LH1-type complex, which was stabilised 3-fold by calcium-ions. Additionally, carotenoid specificity was changed from spheroidene found in Rba. sphaeroides to spirilloxanthin found in Tch. tepidum, with the latter enhancing in vitro formation of LH1. These data show that the C-terminal LH1 α/β domains of Tch. tepidum behave autonomously, and are able to transmit calcium-ion induced conformational changes to BChls bound to the rest of a foreign antenna complex. Thus, elements of foreign antenna complexes, such as calcium-ion binding and blue/red switching of absorption, can be ported into Rhodobacter sphaeroides using careful design processes. Copyright © 2017 The Author(s). Published by Elsevier B.V. All rights reserved.

The organization of LH2 complexes in membranes from Rhodobacter sphaeroides.

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Olsen, John D; Tucker, Jaimey D; Timney, John A; Qian, Pu; Vassilev, Cvetelin; Hunter, C Neil

2008-11-07

The mapping of the photosynthetic membrane of Rhodobacter sphaeroides by atomic force microscopy (AFM) revealed a unique organization of arrays of dimeric reaction center-light harvesting I-PufX (RC-LH1-PufX) core complexes surrounded and interconnected by light-harvesting LH2 complexes (Bahatyrova, S., Frese, R. N., Siebert, C. A., Olsen, J. D., van der Werf, K. O., van Grondelle, R., Niederman, R. A., Bullough, P. A., Otto, C., and Hunter, C. N. (2004) Nature 430, 1058-1062). However, membrane regions consisting solely of LH2 complexes were under-represented in these images because these small, highly curved areas of membrane rendered them difficult to image even using gentle tapping mode AFM and impossible with contact mode AFM. We report AFM imaging of membranes prepared from a mutant of R. sphaeroides, DPF2G, that synthesizes only the LH2 complexes, which assembles spherical intracytoplasmic membrane vesicles of approximately 53 nm diameter in vivo. By opening these vesicles and adsorbing them onto mica to form small, LH2-only membranes for the first time. The transition from highly curved vesicle to the planar sheet is accompanied by a change in the packing of the LH2 complexes such that approximately half of the complexes are raised off the mica surface by approximately 1 nm relative to the rest. This vertical displacement produces a very regular corrugated appearance of the planar membrane sheets. Analysis of the topographs was used to measure the distances and angles between the complexes. These data are used to model the organization of LH2 complexes in the original, curved membrane. The implications of this architecture for the light harvesting function and diffusion of quinones in native membranes of R. sphaeroides are discussed.

Cloning, DNA sequence, and expression of the Rhodobacter sphaeroides cytochrome c/sub 2/ gene

Energy Technology Data Exchange (ETDEWEB)

Donohue, T.J.; McEwan, A.G.; Kaplan, S.

1986-11-01

The Rhodobacter sphaeroides cytochrome c/sub 2/ functions as a mobile electron carrier in both aerobic and photosynthetic electron transport chains. Synthetic deoxyoligonucleotide probes, based on the known amino acid sequence of this protein (M/sub r/ 14,000), were used to identify and clone the cytochrome c/sub 2/ structural gene (cycA). DNA sequence analysis of the cycA gene indicated the presence of a typical procaryotic 21-residue signal sequence, suggesting that this periplasmic protein is synthesized in vivo as a precursor. Synthesis of an immunoreactive cytochrome c/sub 2/ precursor protein (M/sub r/ 15,500) was observed in vitro when plasmids containing the cycA gene were used as templates in an R. sphaeroides coupled transcription-translation system. Approximately 500 base pairs of DNA upstream of the cycA gene was sufficient to allow expression of this gene product in vitro. Northern blot analysis with an internal cycA-specific probe identified at least two possibly monocistronic transcripts present in both different cellular levels and relative stoichiometries in steady-state cells grown under different physiological conditions. The ratio of the small (740-mucleotide) and large (920-nucleotide) cycA-specific mRNA species was dependent on cultural conditions but was not affected by light intensity under photosynthetic conditions. These results suggest that the increase in the cellular level of the cytochrome c/sub 2/ protein found in photosynthetic cells was due, in part, to increased transcription of the single-copy cyc operon.

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

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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.

A cryptochrome-like protein is involved in the regulation of photosynthesis genes in Rhodobacter sphaeroides.

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Hendrischk, Anne-Kathrin; Frühwirth, Sebastian Walter; Moldt, Julia; Pokorny, Richard; Metz, Sebastian; Kaiser, Gebhard; Jäger, Andreas; Batschauer, Alfred; Klug, Gabriele

2009-11-01

Blue light receptors belonging to the cryptochrome/photolyase family are found in all kingdoms of life. The functions of photolyases in repair of UV-damaged DNA as well as of cryptochromes in the light-dependent regulation of photomorphogenetic processes and in the circadian clock in plants and animals are well analysed. In prokaryotes, the only role of members of this protein family that could be demonstrated is DNA repair. Recently, we identified a gene for a cryptochrome-like protein (CryB) in the alpha-proteobacterium Rhodobacter sphaeroides. The protein lacks the typical C-terminal extension of cryptochromes, and is not related to the Cry DASH family. Here we demonstrate that CryB binds flavin adenine dinucleotide that can be photoreduced by blue light. CryB binds single-stranded DNA with very high affinity (K(d) approximately 10(-8) M) but double-stranded DNA and single-stranded RNA with far lower affinity (K(d) approximately 10(-6) M). Despite of that, no in vitro repair activity for pyrimidine dimers in single-stranded DNA could be detected. However, we show that CryB clearly affects the expression of genes for pigment-binding proteins and consequently the amount of photosynthetic complexes in R. sphaeroides. Thus, for the first time a role of a bacterial cryptochrome in gene regulation together with a biological function is demonstrated.

Electron spin relaxation enhancement measurements of interspin distances in human, porcine, and Rhodobacter electron transfer flavoprotein ubiquinone oxidoreductase (ETF QO)

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Fielding, Alistair J.; Usselman, Robert J.; Watmough, Nicholas; Simkovic, Martin; Frerman, Frank E.; Eaton, Gareth R.; Eaton, Sandra S.

2008-02-01

Electron transfer flavoprotein-ubiquinone oxidoreductase (ETF-QO) is a membrane-bound electron transfer protein that links primary flavoprotein dehydrogenases with the main respiratory chain. Human, porcine, and Rhodobacter sphaeroides ETF-QO each contain a single [4Fe-4S] 2+,1+ cluster and one equivalent of FAD, which are diamagnetic in the isolated enzyme and become paramagnetic on reduction with the enzymatic electron donor or with dithionite. The anionic flavin semiquinone can be reduced further to diamagnetic hydroquinone. The redox potentials for the three redox couples are so similar that it is not possible to poise the proteins in a state where both the [4Fe-4S] + cluster and the flavoquinone are fully in the paramagnetic form. Inversion recovery was used to measure the electron spin-lattice relaxation rates for the [4Fe-4S] + between 8 and 18 K and for semiquinone between 25 and 65 K. At higher temperatures the spin-lattice relaxation rates for the [4Fe-4S] + were calculated from the temperature-dependent contributions to the continuous wave linewidths. Although mixtures of the redox states are present, it was possible to analyze the enhancement of the electron spin relaxation of the FAD semiquinone signal due to dipolar interaction with the more rapidly relaxing [4Fe-4S] + and obtain point-dipole interspin distances of 18.6 ± 1 Å for the three proteins. The point-dipole distances are within experimental uncertainty of the value calculated based on the crystal structure of porcine ETF-QO when spin delocalization is taken into account. The results demonstrate that electron spin relaxation enhancement can be used to measure distances in redox poised proteins even when several redox states are present.

Electron spin relaxation enhancement measurements of interspin distances in human, porcine, and Rhodobacter electron transfer flavoprotein-ubiquinone oxidoreductase (ETF-QO).

Science.gov (United States)

Fielding, Alistair J; Usselman, Robert J; Watmough, Nicholas; Simkovic, Martin; Frerman, Frank E; Eaton, Gareth R; Eaton, Sandra S

2008-02-01

Electron transfer flavoprotein-ubiquinone oxidoreductase (ETF-QO) is a membrane-bound electron transfer protein that links primary flavoprotein dehydrogenases with the main respiratory chain. Human, porcine, and Rhodobacter sphaeroides ETF-QO each contain a single [4Fe-4S](2+,1+) cluster and one equivalent of FAD, which are diamagnetic in the isolated enzyme and become paramagnetic on reduction with the enzymatic electron donor or with dithionite. The anionic flavin semiquinone can be reduced further to diamagnetic hydroquinone. The redox potentials for the three redox couples are so similar that it is not possible to poise the proteins in a state where both the [4Fe-4S](+) cluster and the flavoquinone are fully in the paramagnetic form. Inversion recovery was used to measure the electron spin-lattice relaxation rates for the [4Fe-4S](+) between 8 and 18K and for semiquinone between 25 and 65K. At higher temperatures the spin-lattice relaxation rates for the [4Fe-4S](+) were calculated from the temperature-dependent contributions to the continuous wave linewidths. Although mixtures of the redox states are present, it was possible to analyze the enhancement of the electron spin relaxation of the FAD semiquinone signal due to dipolar interaction with the more rapidly relaxing [4Fe-4S](+) and obtain point-dipole interspin distances of 18.6+/-1A for the three proteins. The point-dipole distances are within experimental uncertainty of the value calculated based on the crystal structure of porcine ETF-QO when spin delocalization is taken into account. The results demonstrate that electron spin relaxation enhancement can be used to measure distances in redox poised proteins even when several redox states are present.

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

Studies of DNA supercoiling in vivo and in vitro

Energy Technology Data Exchange (ETDEWEB)

Cook, D.N.

1990-10-01

This thesis describes a number of diverse experiments whose common theme is to elaborate some aspect of DNA supercoiling. The torsion elastic constant of DNA is measure as a function of superhelix density using the technique of picosecond Time Resolved Fluorescence Polarization Anisotropy (FPA) of intercalated ethidium bromide. The results agree with theories which predict that the anisotropy decay should vary with the square root of the relative viscosity. This experiment furthermore demonstrates a sensitivity of FPA to a change in torsion elastic constant of less than 10%. A number of covalently closed DNA samples, ranging in superhelix density from = [minus]0.123 to [plus]0.042, are then examined. A novel method for measuring changes in local supercoiling on a large PNA molecule which is sensitive to changes in supercoiling of regions of chromosomal DNA as short as 1 kilobase in length is presented. Study of chromosomal supercoiling regulating anaerobic gene expression in the facultative photosynthetic bacterium, Rhodobacter capsulatus showed that no stable change in chromosomal supercoiling upon a shift from aerobic respiratory growth to anaerobic photosynthetic conditions. Studies to detect transient changes in DNA supercoiling indicate that DNA downstream from heavily transcribed genes for the photosynthetic reaction center are relaxed or perhaps overwound upon the induction of photosynthetic metabolism. These results are interpreted in terms of the twin domain model of transcriptional supercoiling.

Studies of DNA supercoiling in vivo and in vitro

Energy Technology Data Exchange (ETDEWEB)

Cook, David Nelson [Univ. of California, Berkeley, CA (United States)

1990-10-01

This thesis describes a number of diverse experiments whose common theme is to elaborate some aspect of DNA supercoiling. The torsion elastic constant of DNA is measure as a function of superhelix density using the technique of picosecond Time Resolved Fluorescence Polarization Anisotropy (FPA) of intercalated ethidium bromide. The results agree with theories which predict that the anisotropy decay should vary with the square root of the relative viscosity. This experiment furthermore demonstrates a sensitivity of FPA to a change in torsion elastic constant of less than 10%. A number of covalently closed DNA samples, ranging in superhelix density from = -0.123 to +0.042, are then examined. A novel method for measuring changes in local supercoiling on a large PNA molecule which is sensitive to changes in supercoiling of regions of chromosomal DNA as short as 1 kilobase in length is presented. Study of chromosomal supercoiling regulating anaerobic gene expression in the facultative photosynthetic bacterium, Rhodobacter capsulatus showed that no stable change in chromosomal supercoiling upon a shift from aerobic respiratory growth to anaerobic photosynthetic conditions. Studies to detect transient changes in DNA supercoiling indicate that DNA downstream from heavily transcribed genes for the photosynthetic reaction center are relaxed or perhaps overwound upon the induction of photosynthetic metabolism. These results are interpreted in terms of the twin domain model of transcriptional supercoiling.

The mutation of carotenoids affects the energy transfer in LH2 light harvesting complexes from Rhodobacter sphaeroides 601 at room temperature

International Nuclear Information System (INIS)

Liu Weimin; Liu Yuan; Guo Lijun; Xu Chunhe; Qian Shixiong

2006-01-01

Energy transfer in two kinds of peripheral antenna complexes LH2 from Rhodobacter sphaeroides 601 was studied by absorption, fluorescence emission, time-resolved fluorescence and femtosecond transient absorption spectroscopy at room temperature. These two complexes are LH2 (RS601) and green carotenoid mutated LH2 (GM309). The obtained results demonstrate that: (a) compared with spheroidenes, which have ten carbon-carbon double bonds in native RS601, carotenoids in GM309 were identified as containing neurosporenes with nine carbon-carbon double bonds, which show a significant blue shift of ∼20 nm in the three absorption peaks because of the higher energy levels of neurosporene than those of spheroidene, (b) the higher energy levels of neurosporene in GM309 induce a lower B800 → B850 energy transfer rate and efficiency as compared to that in RS601 resulting from the relatively higher band gap between the donor of B800 and the bridge of the carotenoids (c) the same lifetime of the B850 excited singlet state is observed in these two LH2 complexes

Multi-PAS domain-mediated protein oligomerization of PpsR from Rhodobacter sphaeroides

International Nuclear Information System (INIS)

Heintz, Udo; Meinhart, Anton; Winkler, Andreas

2014-01-01

Crystal structures of two truncated variants of the transcription factor PpsR from R. sphaeroides are presented that enabled the phasing of a triple PAS domain construct. Together, these structures reveal the importance of α-helical PAS extensions for multi-PAS domain-mediated protein oligomerization and function. Per–ARNT–Sim (PAS) domains are essential modules of many multi-domain signalling proteins that mediate protein interaction and/or sense environmental stimuli. Frequently, multiple PAS domains are present within single polypeptide chains, where their interplay is required for protein function. Although many isolated PAS domain structures have been reported over the last decades, only a few structures of multi-PAS proteins are known. Therefore, the molecular mechanism of multi-PAS domain-mediated protein oligomerization and function is poorly understood. The transcription factor PpsR from Rhodobacter sphaeroides is such a multi-PAS domain protein that, in addition to its three PAS domains, contains a glutamine-rich linker and a C-terminal helix–turn–helix DNA-binding motif. Here, crystal structures of two N-terminally and C-terminally truncated PpsR variants that comprise a single (PpsR Q-PAS1 ) and two (PpsR N-Q-PAS1 ) PAS domains, respectively, are presented and the multi-step strategy required for the phasing of a triple PAS domain construct (PpsR ΔHTH ) is illustrated. While parts of the biologically relevant dimerization interface can already be observed in the two shorter constructs, the PpsR ΔHTH structure reveals how three PAS domains enable the formation of multiple oligomeric states (dimer, tetramer and octamer), highlighting that not only the PAS cores but also their α-helical extensions are essential for protein oligomerization. The results demonstrate that the long helical glutamine-rich linker of PpsR results from a direct fusion of the N-cap of the PAS1 domain with the C-terminal extension of the N-domain that plays an important

Photo dynamics of BLUF domain mutant H44R of AppA from Rhodobacter sphaeroides

International Nuclear Information System (INIS)

Zirak, P.; Penzkofer, A.; Hegemann, P.; Mathes, T.

2007-01-01

The photo-cycle dynamics of the H44R mutant of the BLUF domain of the transcriptional anti-repressor protein AppA (AppA-H44R) from the non-sulfur anoxyphototropic purple bacterium Rhodobacter sphaeroides is studied in order to gain information on the involvement of His44 in the photo-cyclic mechanism of the AppA BLUF domain and to add information to the involved processes. The amino acid residue histidine at position 44 is replaced by arginine. A 12 nm red-shifted signalling state is formed upon blue-light excitation, while in wild-type AppA (AppA-wt) the red-shift is 16 nm. The recovery to the receptor dark state is approximately a factor of 2.5 faster (τ rec ∼ 6.5 min) than the recovery of the wild-type counterpart. Extended light exposure of the mutant causes photo-degradation of flavin (mainly free flavin conversion to lumichrome and re-equilibration between free and non-covalently bound flavin) and protein aggregation (showing up as light scattering). No photo-degradation was observed for AppA-wt. The quantum efficiency of signalling-state formation determined by intensity dependent absorption measurements is found to be φ s ∼ 0.3 (for AppA-wt: φ s ∼ 0.24). A two-component single-exponential fluorescence relaxation was observed, which is interpreted as fast fluorescence quenching to an equilibrium value by photo-induced electron transfer followed by slower fluorescence decay due to charge recombination. Based on the experimental findings, an extended photo-cycle model for BLUF domains is proposed

Photo dynamics of BLUF domain mutant H44R of AppA from Rhodobacter sphaeroides

Science.gov (United States)

Zirak, P.; Penzkofer, A.; Hegemann, P.; Mathes, T.

2007-05-01

The photo-cycle dynamics of the H44R mutant of the BLUF domain of the transcriptional anti-repressor protein AppA (AppA-H44R) from the non-sulfur anoxyphototropic purple bacterium Rhodobacter sphaeroides is studied in order to gain information on the involvement of His44 in the photo-cyclic mechanism of the AppA BLUF domain and to add information to the involved processes. The amino acid residue histidine at position 44 is replaced by arginine. A 12 nm red-shifted signalling state is formed upon blue-light excitation, while in wild-type AppA (AppA-wt) the red-shift is 16 nm. The recovery to the receptor dark state is approximately a factor of 2.5 faster ( τrec ≈ 6.5 min) than the recovery of the wild-type counterpart. Extended light exposure of the mutant causes photo-degradation of flavin (mainly free flavin conversion to lumichrome and re-equilibration between free and non-covalently bound flavin) and protein aggregation (showing up as light scattering). No photo-degradation was observed for AppA-wt. The quantum efficiency of signalling-state formation determined by intensity dependent absorption measurements is found to be ϕs ≈ 0.3 (for AppA-wt: ϕs ≈ 0.24). A two-component single-exponential fluorescence relaxation was observed, which is interpreted as fast fluorescence quenching to an equilibrium value by photo-induced electron transfer followed by slower fluorescence decay due to charge recombination. Based on the experimental findings, an extended photo-cycle model for BLUF domains is proposed.

Overexpression of pucC improves the heterologous protein expression level in a Rhodobacter sphaeroides expression system.

Science.gov (United States)

Cheng, L; Chen, G; Ding, G; Zhao, Z; Dong, T; Hu, Z

2015-04-27

The Rhodobacter sphaeroides system has been used to express membrane proteins. However, its low yield has substantially limited its application. In order to promote the protein expression capability of this system, the pucC gene, which plays a crucial role in assembling the R. sphaeroides light-harvesting 2 complex (LH2), was overexpressed. To build a pucC overexpression strain, a pucC overexpression vector was constructed and transformed into R. sphaeroides CQU68. The overexpression efficiency was evaluated by quantitative real-time polymerase chain reaction. A well-used reporter β-glucuronidase (GUS) was fusion-expressed with LH2 to evaluate the heterologous protein expression level. As a result, the cell culture and protein in the pucC overexpression strain showed much higher typical spectral absorption peaks at 800 and 850 nm compared with the non-overexpression strain, suggesting a higher expression level of LH2-GUS fusion protein in the pucC overexpression strain. This result was further confirmed by Western blot, which also showed a much higher level of heterologous protein expression in the pucC overexpression strain. We further compared GUS activity in pucC overexpression and non-overexpression strains, the results of which showed that GUS activity in the pucC overexpression strain was approximately ten-fold that in the non-overexpression strain. These results demonstrate that overexpressed pucC can promote heterologous protein expression levels in R. sphaeroides.

Probing energy transfer events in the light harvesting complex 2 (LH2) of Rhodobacter sphaeroides with two-dimensional spectroscopy.

Science.gov (United States)

Fidler, Andrew F; Singh, Ved P; Long, Phillip D; Dahlberg, Peter D; Engel, Gregory S

2013-10-21

Excitation energy transfer events in the photosynthetic light harvesting complex 2 (LH2) of Rhodobacter sphaeroides are investigated with polarization controlled two-dimensional electronic spectroscopy. A spectrally broadened pulse allows simultaneous measurement of the energy transfer within and between the two absorption bands at 800 nm and 850 nm. The phased all-parallel polarization two-dimensional spectra resolve the initial events of energy transfer by separating the intra-band and inter-band relaxation processes across the two-dimensional map. The internal dynamics of the 800 nm region of the spectra are resolved as a cross peak that grows in on an ultrafast time scale, reflecting energy transfer between higher lying excitations of the B850 chromophores into the B800 states. We utilize a polarization sequence designed to highlight the initial excited state dynamics which uncovers an ultrafast transfer component between the two bands that was not observed in the all-parallel polarization data. We attribute the ultrafast transfer component to energy transfer from higher energy exciton states to lower energy states of the strongly coupled B850 chromophores. Connecting the spectroscopic signature to the molecular structure, we reveal multiple relaxation pathways including a cyclic transfer of energy between the two rings of the complex.

Probing energy transfer events in the light harvesting complex 2 (LH2) of Rhodobacter sphaeroides with two-dimensional spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Fidler, Andrew F.; Singh, Ved P.; Engel, Gregory S. [Department of Chemistry, The Institute for Biophysical Dynamics, and The James Franck Institute, The University of Chicago, Chicago, Illinois 60637 (United States); Long, Phillip D.; Dahlberg, Peter D. [Graduate Program in the Biophysical Sciences, The University of Chicago, Chicago, Illinois 60637 (United States)

2013-10-21

Excitation energy transfer events in the photosynthetic light harvesting complex 2 (LH2) of Rhodobacter sphaeroides are investigated with polarization controlled two-dimensional electronic spectroscopy. A spectrally broadened pulse allows simultaneous measurement of the energy transfer within and between the two absorption bands at 800 nm and 850 nm. The phased all-parallel polarization two-dimensional spectra resolve the initial events of energy transfer by separating the intra-band and inter-band relaxation processes across the two-dimensional map. The internal dynamics of the 800 nm region of the spectra are resolved as a cross peak that grows in on an ultrafast time scale, reflecting energy transfer between higher lying excitations of the B850 chromophores into the B800 states. We utilize a polarization sequence designed to highlight the initial excited state dynamics which uncovers an ultrafast transfer component between the two bands that was not observed in the all-parallel polarization data. We attribute the ultrafast transfer component to energy transfer from higher energy exciton states to lower energy states of the strongly coupled B850 chromophores. Connecting the spectroscopic signature to the molecular structure, we reveal multiple relaxation pathways including a cyclic transfer of energy between the two rings of the complex.

Probing energy transfer events in the light harvesting complex 2 (LH2) of Rhodobacter sphaeroides with two-dimensional spectroscopy

International Nuclear Information System (INIS)

Fidler, Andrew F.; Singh, Ved P.; Engel, Gregory S.; Long, Phillip D.; Dahlberg, Peter D.

2013-01-01

Excitation energy transfer events in the photosynthetic light harvesting complex 2 (LH2) of Rhodobacter sphaeroides are investigated with polarization controlled two-dimensional electronic spectroscopy. A spectrally broadened pulse allows simultaneous measurement of the energy transfer within and between the two absorption bands at 800 nm and 850 nm. The phased all-parallel polarization two-dimensional spectra resolve the initial events of energy transfer by separating the intra-band and inter-band relaxation processes across the two-dimensional map. The internal dynamics of the 800 nm region of the spectra are resolved as a cross peak that grows in on an ultrafast time scale, reflecting energy transfer between higher lying excitations of the B850 chromophores into the B800 states. We utilize a polarization sequence designed to highlight the initial excited state dynamics which uncovers an ultrafast transfer component between the two bands that was not observed in the all-parallel polarization data. We attribute the ultrafast transfer component to energy transfer from higher energy exciton states to lower energy states of the strongly coupled B850 chromophores. Connecting the spectroscopic signature to the molecular structure, we reveal multiple relaxation pathways including a cyclic transfer of energy between the two rings of the complex

Assembly of functional photosystem complexes in Rhodobacter sphaeroides incorporating carotenoids from the spirilloxanthin pathway

Science.gov (United States)

Chi, Shuang C.; Mothersole, David J.; Dilbeck, Preston; Niedzwiedzki, Dariusz M.; Zhang, Hao; Qian, Pu; Vasilev, Cvetelin; Grayson, Katie J.; Jackson, Philip J.; Martin, Elizabeth C.; Li, Ying; Holten, Dewey; Neil Hunter, C.

2015-01-01

Carotenoids protect the photosynthetic apparatus against harmful radicals arising from the presence of both light and oxygen. They also act as accessory pigments for harvesting solar energy, and are required for stable assembly of many light-harvesting complexes. In the phototrophic bacterium Rhodobacter (Rba.) sphaeroides phytoene desaturase (CrtI) catalyses three sequential desaturations of the colourless carotenoid phytoene, extending the number of conjugated carbon–carbon double bonds, N, from three to nine and producing the yellow carotenoid neurosporene; subsequent modifications produce the yellow/red carotenoids spheroidene/spheroidenone (N = 10/11). Genomic crtI replacements were used to swap the native three-step Rba. sphaeroides CrtI for the four-step Pantoea agglomerans enzyme, which re-routed carotenoid biosynthesis and culminated in the production of 2,2′-diketo-spirilloxanthin under semi-aerobic conditions. The new carotenoid pathway was elucidated using a combination of HPLC and mass spectrometry. Premature termination of this new pathway by inactivating crtC or crtD produced strains with lycopene or rhodopin as major carotenoids. All of the spirilloxanthin series carotenoids are accepted by the assembly pathways for LH2 and RC–LH1–PufX complexes. The efficiency of carotenoid-to-bacteriochlorophyll energy transfer for 2,2′-diketo-spirilloxanthin (15 conjugated C 000000000000 000000000000 000000000000 111111111111 000000000000 111111111111 000000000000 000000000000 000000000000 C bonds; N = 15) in LH2 complexes is low, at 35%. High energy transfer efficiencies were obtained for neurosporene (N = 9; 94%), spheroidene (N = 10; 96%) and spheroidenone (N = 11; 95%), whereas intermediate values were measured for lycopene (N = 11; 64%), rhodopin (N = 11; 62%) and spirilloxanthin (N = 13; 39%). The variety and stability of these novel Rba. sphaeroides antenna complexes make them useful experimental models for investigating the

Resonance Raman spectroscopy of 2H-labelled spheroidenes in petroleum ether and in the Rhodobacter sphaeroides reaction centre.

Science.gov (United States)

Kok, P; Köhler, J; Groenen, E J; Gebhard, R; van der Hoef, I; Lugtenburg, J; Farhoosh, R; Frank, H A

1997-03-01

As a step towards the structural analysis of the carotenoid spheroidene in the Rhodobacter sphaeroides reaction centre, we present the resonance Raman spectra of 14-2H, 15-2H, 15'-2H, 14'-2H, 14,15'-2H2 and 15-15'-2H2 spheroidenes in petroleum ether and, except for 14,15'-2H2 spheroidene, in the Rb. sphaeroides R26 reaction center (RC). Analysis of the spectral changes upon isotopic substitution allows a qualitative assignment of most of the vibrational bands to be made. For the all-trans spheroidenes in solution the resonance enhancement of the Raman bands is determined by the participation of carbon carbon stretching modes in the centre of the conjugated chain, the C9 to C15' region. For the RC-bound 15,15'-cis spheroidenes, enhancement is determined by the participation of carbon-carbon stretching modes in the centre of the molecule, the C13 to C13' region. Comparison of the spectra in solution and in the RC reveals evidence for an out-of-plane distortion of the RC-bound spheroidene in the central C14 to C14' region of the carotenoid. The characteristic 1240 cm-1 band in the spectrum of the RC-bound spheroidene has been assigned to a normal mode that contains the coupled C12-C13 and C13'-C12' stretch vibrations.

Photo dynamics of BLUF domain mutant H44R of AppA from Rhodobacter sphaeroides

Energy Technology Data Exchange (ETDEWEB)

Zirak, P. [Institut II - Experimentelle und Angewandte Physik, Universitaet Regensburg, Universitaetstrasse 31, D-93053 Regensburg (Germany); Penzkofer, A. [Institut II - Experimentelle und Angewandte Physik, Universitaet Regensburg, Universitaetstrasse 31, D-93053 Regensburg (Germany)], E-mail: alfons.penzkofer@physik.uni-regensburg.de; Hegemann, P.; Mathes, T. [Institut fuer Biologie, Experimentelle Biophysik, Humboldt-Universitaet zu Berlin, Invalidenstr. 42, D-10115 Berlin (Germany)

2007-05-21

The photo-cycle dynamics of the H44R mutant of the BLUF domain of the transcriptional anti-repressor protein AppA (AppA-H44R) from the non-sulfur anoxyphototropic purple bacterium Rhodobacter sphaeroides is studied in order to gain information on the involvement of His44 in the photo-cyclic mechanism of the AppA BLUF domain and to add information to the involved processes. The amino acid residue histidine at position 44 is replaced by arginine. A 12 nm red-shifted signalling state is formed upon blue-light excitation, while in wild-type AppA (AppA-wt) the red-shift is 16 nm. The recovery to the receptor dark state is approximately a factor of 2.5 faster ({tau}{sub rec} {approx} 6.5 min) than the recovery of the wild-type counterpart. Extended light exposure of the mutant causes photo-degradation of flavin (mainly free flavin conversion to lumichrome and re-equilibration between free and non-covalently bound flavin) and protein aggregation (showing up as light scattering). No photo-degradation was observed for AppA-wt. The quantum efficiency of signalling-state formation determined by intensity dependent absorption measurements is found to be {phi}{sub s} {approx} 0.3 (for AppA-wt: {phi}{sub s} {approx} 0.24). A two-component single-exponential fluorescence relaxation was observed, which is interpreted as fast fluorescence quenching to an equilibrium value by photo-induced electron transfer followed by slower fluorescence decay due to charge recombination. Based on the experimental findings, an extended photo-cycle model for BLUF domains is proposed.

Dynamic modeling of temperature change in outdoor operated tubular photobioreactors.

Science.gov (United States)

Androga, Dominic Deo; Uyar, Basar; Koku, Harun; Eroglu, Inci

2017-07-01

In this study, a one-dimensional transient model was developed to analyze the temperature variation of tubular photobioreactors operated outdoors and the validity of the model was tested by comparing the predictions of the model with the experimental data. The model included the effects of convection and radiative heat exchange on the reactor temperature throughout the day. The temperatures in the reactors increased with increasing solar radiation and air temperatures, and the predicted reactor temperatures corresponded well to the measured experimental values. The heat transferred to the reactor was mainly through radiation: the radiative heat absorbed by the reactor medium, ground radiation, air radiation, and solar (direct and diffuse) radiation, while heat loss was mainly through the heat transfer to the cooling water and forced convection. The amount of heat transferred by reflected radiation and metabolic activities of the bacteria and pump work was negligible. Counter-current cooling was more effective in controlling reactor temperature than co-current cooling. The model developed identifies major heat transfer mechanisms in outdoor operated tubular photobioreactors, and accurately predicts temperature changes in these systems. This is useful in determining cooling duty under transient conditions and scaling up photobioreactors. The photobioreactor design and the thermal modeling were carried out and experimental results obtained for the case study of photofermentative hydrogen production by Rhodobacter capsulatus, but the approach is applicable to photobiological systems that are to be operated under outdoor conditions with significant cooling demands.

Reusing pulp and paper mill effluent as a bioresource to produce biohydrogen through ultrasonicated Rhodobacter sphaeroides

International Nuclear Information System (INIS)

Hay, Jacqueline Xiao Wen; Wu, Ta Yeong; Ng, Boon Junn; Juan, Joon Ching; Md Jahim, Jamaliah

2016-01-01

Highlights: • Ultrasonication pretreatment on R. sphaeroides enhanced biohydrogen production. • Pretreatment using amplitude 30% for 10 min gave the highest biohydrogen yield. • Pretreatment using amplitude 45% for 15 min inhibited biohydrogen production. - Abstract: Pulp and paper industry is a water-intensive industry. This industry commonly produces considerable amount of effluent, especially from virgin raw materials processing. The effluent, namely pulp and paper mill effluent has the potential to adversely affect the receiving watercourses. However, the nutrients in the pulp and paper mill effluent could be reused as a substrate in biohydrogen production. In this study, photofermentative biohydrogen production was investigated using Rhodobacter sphaeroides and pulp and paper mill effluent as a substrate. An application of low power ultrasound on R. sphaeroides was predicted to increase photofermentative biohydrogen production but excessive ultrasound effects might inhibit the production due to possible cell disruption. Hence, various ultrasonication duration (5, 10 and 15 min) and amplitude (15%, 30% and 45%) were applied on the bacteria to determine the recommended ultrasonication conditions for improving biohydrogen production. The recommended conditions were operated at ultrasonication amplitude and duration of 30% and 10 min, respectively. A maximum biohydrogen yield of 9.62 mL bioH_2/mL medium was obtained under this condition, which was 66.7% higher than the result obtained using R. sphaeroides without undergoing ultrasonication (control). The light efficiency and cell concentration were increased by 67% and 150%, respectively, using ultrasonication amplitude and duration of 30% and 10 min, respectively as compared to the control. The present results demonstrated that moderate power of ultrasonication applied on R. sphaeroides was an effective method for enhancing photofermentative biohydrogen production using raw pulp and paper mill effluent as a

Chronic Exposure to Rhodobacter Sphaeroides Extract Lycogen™ Prevents UVA-Induced Malondialdehyde Accumulation and Procollagen I Down-Regulation in Human Dermal Fibroblasts

Science.gov (United States)

Yang, Tsai-Hsiu; Lai, Ying-Hsiu; Lin, Tsuey-Pin; Liu, Wen-Sheng; Kuan, Li-Chun; Liu, Chia-Chyuan

2014-01-01

UVA contributes to the pathogenesis of skin aging by downregulation of procollagen I content and induction of matrix metalloproteinase (MMP)-associated responses. Application of antioxidants such as lycopene has been demonstrated as a convenient way to achieve protection against skin aging. Lycogen™, derived from the extracts of Rhodobacter sphaeroides, exerts several biological effects similar to that of lycopene whereas most of its anti-aging efficacy remains uncertain. In this study, we attempted to examine whether Lycogen™ could suppress malondialdehyde (MDA) accumulation and restore downregulated procollagen I expression induced by UVA exposure. In human dermal fibroblasts Hs68 cells, UVA repressed cell viability and decreased procollagen I protein content accompanied with the induction of MMP-1 and MDA accumulation. Remarkably, incubation with 50 μM Lycogen™ for 24 h ameliorated UVA-induced cell death and restored UVA-induced downregulation of procollagen in a dose-related manner. Lycogen™ treatment also prevented the UVA-induced MMP-1 upregulation and intracellular MDA generation in Hs68 cells. Activation of NFκB levels, one of the downstream events induced by UVA irradiation and MMP-1 induction, were also prevented by Lycogen™ administration. Taken together, our findings demonstrate that Lycogen™ may be an alternative agent that prevents UVA-induced skin aging and could be used in cosmetic and pharmaceutical applications. PMID:24463291

Biochemical analysis and the preliminary crystallographic characterization of D-tagatose 3-epimerase from Rhodobacter sphaeroides.

Science.gov (United States)

Qi, Zhengliang; Zhu, Zhangliang; Wang, Jian-Wen; Li, Songtao; Guo, Qianqian; Xu, Panpan; Lu, Fuping; Qin, Hui-Min

2017-11-09

D-Tagatose 3-epimerase epimerizes D-fructose to yield D-psicose, which is a rare sugar that exists in small quantities in nature and is difficult to synthesize chemically. We aim to explore potential industrial biocatalysts for commercial-scale manufacture of this rare sugar. A D-tagatose 3-epimerase from Rhodobacter sphaeroides (RsDTE) has recently been identified as a D-tagatose 3-epimerase that can epimerize D-fructose to yield D-psicose with a high conversion rate. The purified RsDTE by Ni-affinity chromatography, ionic exchange chromatography and gel filtration forms a tetramer in solution. The maximal activity was in Tris-HCl buffer pH 8.5, and the optimal temperature was at 35 °C. The product, D-psicose, was confirmed using HPLC and NMR. Crystals of RsDTE were obtained using crystal kits and further refined under crystallization conditions such as 10% PEG 8000,0.1 M HEPES pH 7.5, and 8% ethylene glycol at 20 °C using the sitting-drop vapor diffusion method. The RsDTE homology model showed that it possessed the characteristic TIM-barrel fold. Four residues, Glu156, Asp189, Gln215 and Glu250, forms a hydrogen bond network with the active Mn(II) for the hydride transfer reaction. These residues may constitute the catalytic tetrad of RsDTE. The residues around O1, O2 and O3 of the substrates were conserved. However, the binding-site residues are different at O4, O5 and O6. Arg118 formed the unique hydrogen bond with O4 of D-fructose which indicates RsDTE's preference of D-fructose more than any other family enzymes. RsDTE possesses a different metal-binding site. Arg118, forming unique hydrogen bond with O4 of D-fructose, regulates the substrate recognition. The research on D-tagatose 3-epimerase or D-psicose 3-epimerase enzymes attracts enormous commercial interest and would be widely used for rare sugar production in the future.

The prevalence of gene duplications and their ancient origin in Rhodobacter sphaeroides 2.4.1

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Cho Hyuk

2010-12-01

Full Text Available Abstract Background Rhodobacter sphaeroides 2.4.1 is a metabolically versatile organism that belongs to α-3 subdivision of Proteobacteria. The present study was to identify the extent, history, and role of gene duplications in R. sphaeroides 2.4.1, an organism that possesses two chromosomes. Results A protein similarity search (BLASTP identified 1247 orfs (~29.4% of the total protein coding orfs that are present in 2 or more copies, 37.5% (234 gene-pairs of which exist in duplicate copies. The distribution of the duplicate gene-pairs in all Clusters of Orthologous Groups (COGs differed significantly when compared to the COG distribution across the whole genome. Location plots revealed clusters of gene duplications that possessed the same COG classification. Phylogenetic analyses were performed to determine a tree topology predicting either a Type-A or Type-B phylogenetic relationship. A Type-A phylogenetic relationship shows that a copy of the protein-pair matches more with an ortholog from a species closely related to R. sphaeroides while a Type-B relationship predicts the highest match between both copies of the R. sphaeroides protein-pair. The results revealed that ~77% of the proteins exhibited a Type-A phylogenetic relationship demonstrating the ancient origin of these gene duplications. Additional analyses on three other strains of R. sphaeroides revealed varying levels of gene loss and retention in these strains. Also, analyses on common gene pairs among the four strains revealed that these genes experience similar functional constraints and undergo purifying selection. Conclusions Although the results suggest that the level of gene duplication in organisms with complex genome structuring (more than one chromosome seems to be not markedly different from that in organisms with only a single chromosome, these duplications may have aided in genome reorganization in this group of eubacteria prior to the formation of R. sphaeroides as gene

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.

Enhancement of phototrophic hydrogen production by Rhodobacter sphaeroides ZX-5 using a novel strategy - shaking and extra-light supplementation approach

Energy Technology Data Exchange (ETDEWEB)

Li, Xu; Wang, Yong-Hong; Zhang, Si-Liang; Chu, Ju; Zhang, Ming; Huang, Ming-Zhi; Zhuang, Ying-Ping [State Key Laboratory of Bioreactor Engineering, P.O. Box 329, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237 (China)

2009-12-15

Biohydrogen has gained attention due to its potential as a sustainable alternative to conventional methods for hydrogen production. In this study, the effect of light intensity as well as cultivation method (standing- and shaking-culture) on the cell growth and hydrogen production of Rhodobacter sphaeroides ZX-5 were investigated in 38-ml anaerobic photobioreactor with RCVBN medium. Thus, a novel shaking and extra-light supplementation (SELS) approach was developed to enhance the phototrophic H{sub 2} production by R. sphaeroides ZX-5 using malate as the sole carbon source. The optimum illumination condition for shaking-culture by strain ZX-5 increased to 7000-8000 lux, markedly higher than that for standing-culture (4000-5000 lux). Under shaking and elevated illumination (7000-8000 lux), the culture was effective in promoting photo-H{sub 2} production, resulting in a 59% and 56% increase of the maximum and average hydrogen production rate, respectively, in comparison with the culture under standing and 4000-5000 lux conditions. The highest hydrogen-producing rate of 165.9 ml H{sub 2}/l h was observed under the application of SELS approach. To our knowledge, this record is currently the highest hydrogen production rate of non-immobilized purple non-sulphur (PNS) bacteria. This optimal performance of photo-H{sub 2} production using SELS approach is a favorable choice of sustainable and economically feasible strategy to improve phototrophic H{sub 2} production efficiency. (author)

Quenching Capabilities of Long-Chain Carotenoids in Light-Harvesting-2 Complexes from Rhodobacter sphaeroides with an Engineered Carotenoid Synthesis Pathway.

Science.gov (United States)

Dilbeck, Preston L; Tang, Qun; Mothersole, David J; Martin, Elizabeth C; Hunter, C Neil; Bocian, David F; Holten, Dewey; Niedzwiedzki, Dariusz M

2016-06-23

Six light-harvesting-2 complexes (LH2) from genetically modified strains of the purple photosynthetic bacterium Rhodobacter (Rb.) sphaeroides were studied using static and ultrafast optical methods and resonance Raman spectroscopy. These strains were engineered to incorporate carotenoids for which the number of conjugated groups (N = NC═C + NC═O) varies from 9 to 15. The Rb. sphaeroides strains incorporate their native carotenoids spheroidene (N = 10) and spheroidenone (N = 11), as well as longer-chain analogues including spirilloxanthin (N = 13) and diketospirilloxantion (N = 15) normally found in Rhodospirillum rubrum. Measurements of the properties of the carotenoid first singlet excited state (S1) in antennas from the Rb. sphaeroides set show that carotenoid-bacteriochlorophyll a (BChl a) interactions are similar to those in LH2 complexes from various other bacterial species and thus are not significantly impacted by differences in polypeptide composition. Instead, variations in carotenoid-to-BChl a energy transfer are primarily regulated by the N-determined energy of the carotenoid S1 excited state, which for long-chain (N ≥ 13) carotenoids is not involved in energy transfer. Furthermore, the role of the long-chain carotenoids switches from a light-harvesting supporter (via energy transfer to BChl a) to a quencher of the BChl a S1 excited state B850*. This quenching is manifested as a substantial (∼2-fold) reduction of the B850* lifetime and the B850* fluorescence quantum yield for LH2 housing the longest carotenoids.

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

Effects of the cryptochrome CryB from Rhodobacter sphaeroides on global gene expression in the dark or blue light or in the presence of singlet oxygen.

Directory of Open Access Journals (Sweden)

Sebastian Frühwirth

Full Text Available Several regulators are controlling the formation of the photosynthetic apparatus in the facultatively photosynthetic bacterium Rhodobacter sphaeroides. Among the proteins affecting photosynthesis gene expression is the blue light photoreceptor cryptochrome CryB. This study addresses the effect of CryB on global gene expression. The data reveal that CryB does not only influence photosynthesis gene expression but also genes for the non-photosynthetic energy metabolism like citric acid cycle and oxidative phosphorylation. In addition several genes involved in RNA processing and in transcriptional regulation are affected by a cryB deletion. Although CryB was shown to undergo a photocycle it does not only affect gene expression in response to blue light illumination but also in response to singlet oxygen stress conditions. While there is a large overlap in these responses, some CryB-dependent effects are specific for blue-light or photooxidative stress. In addition to protein-coding genes some genes for sRNAs show CryB-dependent expression. These findings give new insight into the function of bacterial cryptochromes and demonstrate for the first time a function in the oxidative stress response.

Effect of co-substrate on production of poly-β- hydroxybutyrate (PHB and copolymer PHBV from newly identified mutant Rhodobacter sphaeroides U7 cultivated under aerobic-dark condition

Directory of Open Access Journals (Sweden)

Kemarajt Kemavongse

2007-07-01

Full Text Available Photosynthetic bacterial mutant strain U7 was identified using both classical and molecular (16S rDNA techniques to be Rhodobacter sphaeroides. The glutamate-acetate (GA medium containing sodium acetate and sodium glutamate as carbon and nitrogen sources was used for production of poly-β-hydroxybutyrate (PHB from R. sphaeroides U7 cultivated under aerobic-dark condition (200 rpm at 37oC. Effect of auxiliary carbon sources (propionate and valerate and concentrations (molar ratio of 40/0, 40/20, 40/40 and 40/80 on copolymer production were studied. Both combinations of acetate with valerate and acetate with propionate were found to induce the accumulation of poly-β-hydroxybutyrate-co-β-hydroxyvalerate (PHBV within the cell. Acetate with propionate in the molar ratio of 40/40 gave the highest poly-β-hydroxyalkanoates (PHA content (77.68%, followed by acetate with valerate at the same molar ratio (77.42%. Although their polymer contents were similar, the presence of 40 mM valerate gave more than 4 times higher hydroxyvalerate (HV fraction (84.77% than in the presence of 40 mM propionate (19.12% HV fraction.

Elimination of polarity in the carotenoid terminus promotes the exposure of B850-binding sites (Tyr 44, 45) and ANS-mediated energy transfer in LH2 complexes of Rhodobacter sphaeroides.

Science.gov (United States)

Liu, Yuan; Wu, Yongqiang; Xu, Chunhe

2004-12-10

Carotenoids in the peripheral light-harvesting complexes (LH2) of the green mutant (GM309) of Rhodobacter sphaeroides were identified as containing neurosporenes, which lack the polar CH(3)O group, compared to spheroidenes in native-LH2 of R. sphaeroides 601. After LH2 complexes were treated with 1-anilino-8-naphthalene sulfonate (ANS), new energy transfer pathways from ANS or tryptophan to carotenoids were discovered in both native- and GM309-LH2. The carotenoid fluorescence intensity of GM309-LH2 was greater than that of native-LH2 when bound with ANS, suggesting that the elimination of polarity in the neurosporene increases the energy transfer from ANS to carotenoid. The fact that two alpha-tyrosines (alpha-Tyr 44, 45, B850-binding sites) in each alpha-apoprotein of GM309-LH2 were more easily modified than those of native-LH2 by N-acetylimidazole (NAI) indicates that the elimination of polarity in the neurosporene terminus increases the exposure of these sites to solution.

Resonance Raman and surface-enhanced resonance Raman spectra of LH2 antenna complex from Rhodobacter sphaeroides and Ectothiorhodospira sp. excited in the Qx and Qy transitions.

Science.gov (United States)

Chumanov, G; Picorel, R; Ortiz de Zarate, I; Cotton, T M; Seibert, M

2000-05-01

Well-resolved vibrational spectra of LH2 complex isolated from two photosynthetic bacteria, Rhodobacter sphaeroides and Ectothiorhodospira sp., were obtained using surface-enhanced resonance Raman scattering (SERRS) exciting into the Qx and the Qy transitions of bacteriochlorophyll a. High-quality SERRS spectra in the Qy region were accessible because the strong fluorescence background was quenched near the roughened Ag surface. A comparison of the spectra obtained with 590 nm and 752 nm excitation in the mid- and low-frequency regions revealed spectral differences between the two LH2 complexes as well as between the LH2 complexes and isolated bacteriochlorophyll a. Because peripheral modes of pigments contribute mainly to the low-frequency spectral region, frequencies and intensities of many vibrational bands in this region are affected by interactions with the protein. The results demonstrate that the microenvironment surrounding the pigments within the two LH2 complexes is somewhat different, despite the fact that the complexes exhibit similar electronic absorption spectra. These differences are most probably due to specific pigment-pigment and pigment-protein interactions within the LH2 complexes, and the approach might be useful for addressing subtle static and dynamic structural variances between pigment-protein complexes from different sources or in complexes altered chemically or genetically.

NCBI nr-aa BLAST: CBRC-RMAC-01-0051 [SEVENS

Lifescience Database Archive (English)

Full Text Available CBRC-RMAC-01-0051 ref|YP_001033817.1| Ice nucleation protein [Rhodobacter sphaeroid...es 2.4.1] gb|ABA81712.1| Ice nucleation protein [Rhodobacter sphaeroides 2.4.1] YP_001033817.1 0.016 26% ...

NCBI nr-aa BLAST: CBRC-OLAT-26-0102 [SEVENS

Lifescience Database Archive (English)

Full Text Available CBRC-OLAT-26-0102 ref|YP_001033817.1| Ice nucleation protein [Rhodobacter sphaeroid...es 2.4.1] gb|ABA81712.1| Ice nucleation protein [Rhodobacter sphaeroides 2.4.1] YP_001033817.1 0.45 25% ...

NCBI nr-aa BLAST: CBRC-XTRO-01-0470 [SEVENS

Lifescience Database Archive (English)

Full Text Available CBRC-XTRO-01-0470 ref|YP_001033817.1| Ice nucleation protein [Rhodobacter sphaeroid...es 2.4.1] gb|ABA81712.1| Ice nucleation protein [Rhodobacter sphaeroides 2.4.1] YP_001033817.1 1e-12 25% ...

NCBI nr-aa BLAST: CBRC-XTRO-01-0267 [SEVENS

Lifescience Database Archive (English)

Full Text Available CBRC-XTRO-01-0267 ref|YP_001033817.1| Ice nucleation protein [Rhodobacter sphaeroid...es 2.4.1] gb|ABA81712.1| Ice nucleation protein [Rhodobacter sphaeroides 2.4.1] YP_001033817.1 6e-27 25% ...

NCBI nr-aa BLAST: CBRC-TNIG-22-0265 [SEVENS

Lifescience Database Archive (English)

Full Text Available CBRC-TNIG-22-0265 ref|YP_001033817.1| Ice nucleation protein [Rhodobacter sphaeroid...es 2.4.1] gb|ABA81712.1| Ice nucleation protein [Rhodobacter sphaeroides 2.4.1] YP_001033817.1 4e-36 37% ...

NCBI nr-aa BLAST: CBRC-OGAR-01-0310 [SEVENS

Lifescience Database Archive (English)

Full Text Available CBRC-OGAR-01-0310 ref|YP_001033817.1| Ice nucleation protein [Rhodobacter sphaeroid...es 2.4.1] gb|ABA81712.1| Ice nucleation protein [Rhodobacter sphaeroides 2.4.1] YP_001033817.1 4e-07 24% ...

ORF Alignment: NC_002977 [GENIUS II[Archive

Lifescience Database Archive (English)

Full Text Available y ... [Methylococcus capsulatus str. Bath] ... Length = 76 ... Query: 323 ARALADGGNYQAAERLCQSHLASHPHDPE...VHALLGIVMSAANRDDEALRYFRQALYLAPS 382 ... ARALADGGNYQAAERLCQSHLASHPHDPE...VHALLGIVMSAANRDDEALRYFRQALYLAPS Sbjct: 1 ... ARALADGGNYQAAERLCQSHLASHPHDPEVHALLGIVMSAANRDDEALRYFRQALYLAPS 60 ...

ORF Alignment: NC_002977 [GENIUS II[Archive

Lifescience Database Archive (English)

Full Text Available ... domain protein [Methylococcus capsulatus str. Bath] ... Length = 64 ... Query: 239 GTVLSFFHEKGFGFITPDNGGDNFFFHVSDLT...GIEASDVCAGLRISFNAGRNDKGLAAHN 298 ... GTVLSFFHEKGFGFITPDNGGDNFFFHVSDLT...GIEASDVCAGLRISFNAGRNDKGLAAHN Sbjct: 1 ... GTVLSFFHEKGFGFITPDNGGDNFFFHVSDLTGIEASDVCAGLRISFNAGRNDKGLAAHN 60 ...

Monomeric RC-LH1 core complexes retard LH2 assembly and intracytoplasmic membrane formation in PufX-minus mutants of Rhodobacter sphaeroides.

Science.gov (United States)

Adams, Peter G; Mothersole, David J; Ng, Irene W; Olsen, John D; Hunter, C Neil

2011-09-01

In the model photosynthetic bacterium Rhodobacter sphaeroides domains of light-harvesting 2 (LH2) complexes surround and interconnect dimeric reaction centre-light-harvesting 1-PufX (RC-LH1-PufX) 'core' complexes, forming extensive networks for energy transfer and trapping. These complexes are housed in spherical intracytoplasmic membranes (ICMs), which are assembled in a stepwise process where biosynthesis of core complexes tends to dominate the early stages of membrane invagination. The kinetics of LH2 assembly were measured in PufX mutants that assemble monomeric core complexes, as a consequence of either a twelve-residue N-terminal truncation of PufX (PufXΔ12) or the complete removal of PufX (PufX(-)). Lower rates of LH2 assembly and retarded maturation of membrane invagination were observed for the larger and less curved ICM from the PufX(-) mutant, consistent with the proposition that local membrane curvature, initiated by arrays of bent RC-LH1-PufX dimers, creates a favourable environment for stable assembly of LH2 complexes. Transmission electron microscopy and high-resolution atomic force microscopy were used to examine ICM morphology and membrane protein organisation in these mutants. Some partitioning of core and LH2 complexes was observed in PufX(-) membranes, resulting in locally ordered clusters of monomeric RC-LH1 complexes. The distribution of core and LH2 complexes in the three types of membrane examined is consistent with previous models of membrane curvature and domain formation (Frese et al., 2008), which demonstrated that a combination of crowding and asymmetries in sizes and shapes of membrane protein complexes drives membrane organisation. 2011 Elsevier B.V. All rights reserved.

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

Requirement of histidine 217 for ubiquinone reductase activity (Qi site) in the cytochrome bc1 complex.

Science.gov (United States)

Gray, K A; Dutton, P L; Daldal, F

1994-01-25

Folding models suggest that the highly conserved histidine 217 of the cytochrome b subunit from the cytochrome bc1 complex is close to the quinone reductase (Qi) site. This histidine (bH217) in the cytochrome b polypeptide of the photosynthetic bacterium Rhodobacter capsulatus has been replaced with three other residues, aspartate (D), arginine (R), and leucine (L). bH217D and bH217R are able to grow photoheterotrophically and contain active cytochrome bc1 complexes (60% of wild-type activity), whereas the bH217L mutant is photosynthetically incompetent and contains a cytochrome bc1 complex that has only 10% of the wild-type activity. Single-turnover flash-activated electron transfer experiments show that cytochrome bH is reduced via the Qo site with near native rates in the mutant strains but that electron transfer between cytochrome bH and quinone bound at the Qi site is greatly slowed. These results are consistent with redox midpoint potential (Em) measurements of the cytochrome b subunit hemes and the Qi site quinone. The Em values of cyt bL and bH are approximately the same in the mutants and wild type, although the mutant strains have a larger relative concentration of what may be the high-potential form of cytochrome bH, called cytochrome b150. However, the redox properties of the semiquinone at the Qi site are altered significantly. The Qi site semiquinone stability constant of bH217R is 10 times higher than in the wild type, while in the other two strains (bH217D and bH217L) the stability constant is much lower than in the wild type. Thus H217 appears to have major effects on the redox properties of the quinone bound at the Qi site. These data are incorporated into a suggestion that H217 forms part of the binding pocket of the Qi site in a manner reminiscent of the interaction between quinone bound at the Qb site and H190 of the L subunit of the bacterial photosynthetic reaction center.

The Vitamin B12-Dependent Photoreceptor AerR Relieves Photosystem Gene Repression by Extending the Interaction of CrtJ with Photosystem Promoters

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Mingxu Fang

2017-03-01

Full Text Available Purple nonsulfur bacteria adapt their physiology to a wide variety of environmental conditions often through the control of transcription. One of the main transcription factors involved in controlling expression of the Rhodobacter capsulatus photosystem is CrtJ, which functions as an aerobic repressor of photosystem genes. Recently, we reported that a vitamin B12 binding antirepressor of CrtJ called AerR is required for anaerobic expression of the photosystem. However, the mechanism whereby AerR regulates CrtJ activity is unclear. In this study, we used a combination of next-generation sequencing and biochemical methods to globally identify genes under control of CrtJ and the role of AerR in controlling this regulation. Our results indicate that CrtJ has a much larger regulon than previously known, with a surprising regulatory function under both aerobic and anaerobic photosynthetic growth conditions. A combination of in vivo chromatin immunoprecipitation-DNA sequencing (ChIP-seq and ChIP-seq and exonuclease digestion (ChIP-exo studies and in vitro biochemical studies demonstrate that AerR forms a 1:2 complex with CrtJ (AerR-CrtJ2 and that this complex binds to many promoters under photosynthetic conditions. The results of in vitro and in vivo DNA binding studies indicate that AerR-CrtJ2 anaerobically forms an extended interaction with the bacteriochlorophyll bchC promoter to relieve repression by CrtJ. This is contrasted by aerobic growth conditions where CrtJ alone functions as an aerobic repressor of bchC expression. These results indicate that the DNA binding activity of CrtJ is modified by interacting with AerR in a redox-regulated manner and that this interaction alters CrtJ’s function.

Role of PufX protein in photosynthetic growth of Rhodobacter sphaeroides. 1. PufX is required for efficient light-driven electron transfer and photophosphorylation under anaerobic conditions.

Science.gov (United States)

Barz, W P; Francia, F; Venturoli, G; Melandri, B A; Verméglio, A; Oesterhelt, D

1995-11-21

The pufX gene is essential for photoheterotrophic growth of the purple bacterium Rhodobacter sphaeroides. In order to analyze the molecular function of the PufX membrane protein, we constructed a chromosomal pufX deletion mutant and phenotypically compared it to a pufX+ control strain and to two suppressor mutants which are able to grow photosynthetically in the absence of pufX. Using this genetic background, we confirmed that PufX is required for photoheterotrophic growth under anaerobic conditions, although all components of the photosynthetic apparatus were present in similar amounts in all strains investigated. We show that the deletion of PufX is not lethal for illuminated pufX- cells, suggesting that PufX is required for photosynthetic cell division. Since chromatophores isolated from the pufX- mutant were found to be unsealed vesicles, the role of PufX in photosynthetic energy transduction was studied in vivo. We show that PufX is essential for light-induced ATP synthesis (photophosphorylation) in anaerobically incubated cells. Measurements of absorption changes induced by a single turnover flash demonstrated that PufX is not required for electron flow through the reaction center and the cytochrome bc1 complex under anaerobic conditions. During prolonged illumination, however, PufX is essential for the generation of a sufficiently large membrane potential to allow photosynthetic growth. These in vivo results demonstrate that under anaerobic conditions PufX plays an essential role in facilitating effective interaction of the components of the photosynthetic apparatus.

Functional characteristics of spirilloxanthin and keto-bearing Analogues in light-harvesting LH2 complexes from Rhodobacter sphaeroides with a genetically modified carotenoid synthesis pathway.

Science.gov (United States)

Niedzwiedzki, Dariusz M; Dilbeck, Preston L; Tang, Qun; Mothersole, David J; Martin, Elizabeth C; Bocian, David F; Holten, Dewey; Hunter, C Neil

2015-01-01

Light-harvesting 2 (LH2) complexes from a genetically modified strain of the purple photosynthetic bacterium Rhodobacter (Rba.) sphaeroides were studied using static and ultrafast optical methods and resonance Raman spectroscopy. Carotenoid synthesis in the Rba. sphaeroides strain was engineered to redirect carotenoid production away from spheroidene into the spirilloxanthin synthesis pathway. The strain assembles LH2 antennas with substantial amounts of spirilloxanthin (total double-bond conjugation length N=13) if grown anaerobically and of keto-bearing long-chain analogs [2-ketoanhydrorhodovibrin (N=13), 2-ketospirilloxanthin (N=14) and 2,2'-diketospirilloxanthin (N=15)] if grown semi-aerobically (with ratios that depend on growth conditions). We present the photophysical, electronic, and vibrational properties of these carotenoids, both isolated in organic media and assembled within LH2 complexes. Measurements of excited-state energy transfer to the array of excitonically coupled bacteriochlorophyll a molecules (B850) show that the mean lifetime of the first singlet excited state (S1) of the long-chain (N≥13) carotenoids does not change appreciably between organic media and the protein environment. In each case, the S1 state appears to lie lower in energy than that of B850. The energy-transfer yield is ~0.4 in LH2 (from the strain grown aerobically or semi-aerobically), which is less than half that achieved for LH2 that contains short-chain (N≤11) analogues. Collectively, the results suggest that the S1 excited state of the long-chain (N≥13) carotenoids participates little if at all in carotenoid-to-BChl a energy transfer, which occurs predominantly via the carotenoid S2 excited state in these antennas. Copyright © 2015 Elsevier B.V. All rights reserved.

ORF Alignment: NC_002977 [GENIUS II[Archive

Lifescience Database Archive (English)

Full Text Available NC_002977 gi|53804693 >1fgjA 20 492 48 517 e-179 ... gb|AAU92745.1| hydroxylamine oxy...doreductase [Methylococcus capsulatus str. Bath] ... ref|YP_113436.1| hydroxylamine oxydoreductase ...

Development of biological platform for the autotrophic production of biofuels

Science.gov (United States)

Khan, Nymul

The research described herein is aimed at developing an advanced biofuel platform that has the potential to surpass the natural rate of solar energy capture and CO2 fixation. The underlying concept is to use the electricity from a renewable source, such as wind or solar, to capture CO 2 via a biological agent, such as a microbe, into liquid fuels that can be used for the transportation sector. In addition to being renewable, the higher rate of energy capture by photovoltaic cells than natural photosynthesis is expected to facilitate higher rate of liquid fuel production than traditional biofuel processes. The envisioned platform is part of ARPA-E's (Advanced Research Projects Agency - Energy) Electrofuels initiative which aims at supplementing the country's petroleum based fuel production with renewable liquid fuels that can integrate easily with the existing refining and distribution infrastructure (http://arpae. energy.gov/ProgramsProjects/Electrofuels.aspx). The Electrofuels initiative aimed to develop liquid biofuels that avoid the issues encountered in the current generation of biofuels: (1) the reliance of biomass-derived technologies on the inefficient process of photosynthesis, (2) the relatively energy- and resource-intensive nature of agronomic processes, and (3) the occupation of large areas of arable land for feedstock production. The process proceeds by the capture of solar energy into electrical energy via photovoltaic cells, using the generated electricity to split water into molecular hydrogen (H2) and oxygen (O2), and feeding these gases, along with carbon dioxide (CO2) emitted from point sources such as a biomass or coal-fired power plant, to a microbial bioprocessing platform. The proposed microbial bioprocessing platform leverages a chemolithoautotrophic microorganism (Rhodobacter capsulatus or Ralstonia eutropha) naturally able to utilize these gases as growth substrates, and genetically modified to produce a triterpene hydrocarbon fuel

Photodynamics of BLUF domain proteins: a new class of the biological blue-light photoreceptors

OpenAIRE

Zirak Yousefabadi, Peyman

2008-01-01

BLUF domains are light sensors of many microorganisms. They are present in the multi-domain proteins e.g. AppA from the phototrophic proteobacterium Rhodobacter sphaeroides, YcgF from Escherichia coli, PAC (photoactive adenylyl cyclase) from the unicellular flagellate Euglena gracilis and single domain proteins e.g. BlrB from Rhodobacter sphaeroides, Slr1694 from cyanobacterium Synechocystis sp.PCC6803, and Tll0078 of the thermophilic unicellular cyanobacterium Thermosynechococcus elongates B...

ORF Alignment: NC_002977 [GENIUS II[Archive

Lifescience Database Archive (English)

Full Text Available NC_002977 gi|53804116 >1dlwA 19 113 26 120 5e-13 ... gb|AAU92168.1| protozoan/cyanoba...cterial globin family protein [Methylococcus ... capsulatus str. Bath] ref|YP_114018.1| ... protozoa

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.

Respiratory Syncytial Virus Fusion Protein-Induced Toll-Like Receptor 4 (TLR4) Signaling Is Inhibited by the TLR4 Antagonists Rhodobacter sphaeroides Lipopolysaccharide and Eritoran (E5564) and Requires Direct Interaction with MD-2

Science.gov (United States)

Rallabhandi, Prasad; Phillips, Rachel L.; Boukhvalova, Marina S.; Pletneva, Lioubov M.; Shirey, Kari Ann; Gioannini, Theresa L.; Weiss, Jerrold P.; Chow, Jesse C.; Hawkins, Lynn D.; Vogel, Stefanie N.; Blanco, Jorge C. G.

2012-01-01

ABSTRACT Respiratory syncytial virus (RSV) is a leading cause of infant mortality worldwide. Toll-like receptor 4 (TLR4), a signaling receptor for structurally diverse microbe-associated molecular patterns, is activated by the RSV fusion (F) protein and by bacterial lipopolysaccharide (LPS) in a CD14-dependent manner. TLR4 signaling by LPS also requires the presence of an additional protein, MD-2. Thus, it is possible that F protein-mediated TLR4 activation relies on MD-2 as well, although this hypothesis has not been formally tested. LPS-free RSV F protein was found to activate NF-κB in HEK293T transfectants that express wild-type (WT) TLR4 and CD14, but only when MD-2 was coexpressed. These findings were confirmed by measuring F-protein-induced interleukin 1β (IL-1β) mRNA in WT versus MD-2−/− macrophages, where MD-2−/− macrophages failed to show IL-1β expression upon F-protein treatment, in contrast to the WT. Both Rhodobacter sphaeroides LPS and synthetic E5564 (eritoran), LPS antagonists that inhibit TLR4 signaling by binding a hydrophobic pocket in MD-2, significantly reduced RSV F-protein-mediated TLR4 activity in HEK293T-TLR4–CD14–MD-2 transfectants in a dose-dependent manner, while TLR4-independent NF-κB activation by tumor necrosis factor alpha (TNF-α) was unaffected. In vitro coimmunoprecipitation studies confirmed a physical interaction between native RSV F protein and MD-2. Further, we demonstrated that the N-terminal domain of the F1 segment of RSV F protein interacts with MD-2. These data provide new insights into the importance of MD-2 in RSV F-protein-mediated TLR4 activation. Thus, targeting the interaction between MD-2 and RSV F protein may potentially lead to novel therapeutic approaches to help control RSV-induced inflammation and pathology. PMID:22872782

X-ray absorption spectroscopic studies of the dinuclear iron center in methane monooxygenase and the sulfure and chlorine centers in photographic materials

Energy Technology Data Exchange (ETDEWEB)

DeWitt, J.G.

1992-12-01

The dinuclear iron center of the hydroxylase component of soluble methane monooxygenase (MMO) from Methylococcus capsulatus and Methylosinus trichosporiwn has been studied by X-ray absorption spectroscopy. Analysis of the Fe K-edge EXAFS revealed that the first shell coordination of the Fe(HI)Fe(IH) oxidized state of the hydroxylase from M. capsulatus consists of approximately 6 N and 0 atoms at an average distance of 2.04 [Angstrom]. The Fe-Fe distance was determined to be 3.4 [Angstrom]. No evidence for the presence of a short oxo bridge in the iron center of the oxidized hydroxylase was found, suggesting that the active site of MMO is significantly different from the active sites of the dinuclear iron proteins hemery and ribonucleotide reductase. In addition, the results of the first shell fits suggest that there are more oxygen than nitrogen donor ligands.

X-ray absorption spectroscopic studies of the dinuclear iron center in methane monooxygenase and the sulfure and chlorine centers in photographic materials

Energy Technology Data Exchange (ETDEWEB)

DeWitt, Jane G. [Stanford Univ., CA (United States)

1992-12-01

The dinuclear iron center of the hydroxylase component of soluble methane monooxygenase (MMO) from Methylococcus capsulatus and Methylosinus trichosporiwn has been studied by X-ray absorption spectroscopy. Analysis of the Fe K-edge EXAFS revealed that the first shell coordination of the Fe(HI)Fe(IH) oxidized state of the hydroxylase from M. capsulatus consists of approximately 6 N and 0 atoms at an average distance of 2.04 Å. The Fe-Fe distance was determined to be 3.4 Å. No evidence for the presence of a short oxo bridge in the iron center of the oxidized hydroxylase was found, suggesting that the active site of MMO is significantly different from the active sites of the dinuclear iron proteins hemery and ribonucleotide reductase. In addition, the results of the first shell fits suggest that there are more oxygen than nitrogen donor ligands.

Bioaugmentation of Lactobacillus delbrueckii ssp. bulgaricus TISTR 895 to enhance bio-hydrogen production of Rhodobacter sphaeroides KKU-PS5.

Science.gov (United States)

Laocharoen, Sucheera; Reungsang, Alissara; Plangklang, Pensri

2015-01-01

Bioaugmentation or an addition of the desired microorganisms or specialized microbial strains into the anaerobic digesters can enhance the performance of microbial community in the hydrogen production process. Most of the studies focused on a bioaugmentation of native microorganisms capable of producing hydrogen with the dark-fermentative hydrogen producers while information on bioaugmentation of purple non-sulfur photosynthetic bacteria (PNSB) with lactic acid-producing bacteria (LAB) is still limited. In our study, bioaugmentation of Rhodobacter sphaeroides KKU-PS5 with Lactobacillus delbrueckii ssp. bulgaricus TISTR 895 was conducted as a method to produce hydrogen. Unfortunately, even though well-characterized microorganisms were used in the fermentation system, a cultivation of two different organisms in the same bioreactor was still difficult because of the differences in their metabolic types, optimal conditions, and nutritional requirements. Therefore, evaluation of the physical and chemical factors affecting hydrogen production of PNSB augmented with LAB was conducted using a full factorial design followed by response surface methodology (RSM) with central composite design (CCD). A suitable LAB/PNSB ratio and initial cell concentration were found to be 1/12 (w/w) and 0.15 g/L, respectively. The optimal initial pH, light intensity, and Mo concentration obtained from RSM with CCD were 7.92, 8.37 klux and 0.44 mg/L, respectively. Under these optimal conditions, a cumulative hydrogen production of 3396 ± 66 mL H2/L, a hydrogen production rate (HPR) of 9.1 ± 0.2 mL H2/L h, and a hydrogen yield (HY) of 9.65 ± 0.23 mol H2/mol glucose were obtained. KKU-PS5 augmented with TISTR 895 produced hydrogen from glucose at a relatively high HY, 9.65 ± 0.23 mol H2/mol glucose, i.e., 80 % of the theoretical yield. The ratio of the strains TISTR 895/KKU-PS5 and their initial cell concentrations affected the rate of lactic acid production and its

Environmental factors influencing gene transfer agent (GTA mediated transduction in the subtropical ocean.

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Lauren D McDaniel

Full Text Available Microbial genomic sequence analyses have indicated widespread horizontal gene transfer (HGT. However, an adequate mechanism accounting for the ubiquity of HGT has been lacking. Recently, high frequencies of interspecific gene transfer have been documented, catalyzed by Gene Transfer Agents (GTAs of marine α-Proteobacteria. It has been proposed that the presence of bacterial genes in highly purified viral metagenomes may be due to GTAs. However, factors influencing GTA-mediated gene transfer in the environment have not yet been determined. Several genomically sequenced strains containing complete GTA sequences similar to Rhodobacter capsulatus (RcGTA, type strain were screened to ascertain if they produced putative GTAs, and at what abundance. Five of nine marine strains screened to date spontaneously produced virus-like particles (VLP's in stationary phase. Three of these strains have demonstrated gene transfer activity, two of which were documented by this lab. These two strains Roseovarius nubinhibens ISM and Nitratireductor 44B9s, were utilized to produce GTAs designated RnGTA and NrGTA and gene transfer activity was verified in culture. Cell-free preparations of purified RnGTA and NrGTA particles from marked donor strains were incubated with natural microbial assemblages to determine the level of GTA-mediated gene transfer. In conjunction, several ambient environmental parameters were measured including lysogeny indicated by prophage induction. GTA production in culture systems indicated that approximately half of the strains produced GTA-like particles and maximal GTA counts ranged from 10-30% of host abundance. Modeling of GTA-mediated gene transfer frequencies in natural samples, along with other measured environmental variables, indicated a strong relationship between GTA mediated gene transfer and the combined factors of salinity, multiplicity of infection (MOI and ambient bacterial abundance. These results indicate that GTA

The human gastric pathogen Helicobacter pylori has a potential acetone carboxylase that enhances its ability to colonize mice

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Weinberg Michael V

2008-01-01

Full Text Available Abstract Background Helicobacter pylori colonizes the human stomach and is the etiological agent of peptic ulcer disease. All three H. pylori strains that have been sequenced to date contain a potential operon whose products share homology with the subunits of acetone carboxylase (encoded by acxABC from Xanthobacter autotrophicus strain Py2 and Rhodobacter capsulatus strain B10. Acetone carboxylase catalyzes the conversion of acetone to acetoacetate. Genes upstream of the putative acxABC operon encode enzymes that convert acetoacetate to acetoacetyl-CoA, which is metabolized further to generate two molecules of acetyl-CoA. Results To determine if the H. pylori acxABC operon has a role in host colonization the acxB homolog in the mouse-adapted H. pylori SS1 strain was inactivated with a chloramphenicol-resistance (cat cassette. In mouse colonization studies the numbers of H. pylori recovered from mice inoculated with the acxB:cat mutant were generally one to two orders of magnitude lower than those recovered from mice inoculated with the parental strain. A statistical analysis of the data using a Wilcoxin Rank test indicated the differences in the numbers of H. pylori isolated from mice inoculated with the two strains were significant at the 99% confidence level. Levels of acetone associated with gastric tissue removed from uninfected mice were measured and found to range from 10–110 μmols per gram wet weight tissue. Conclusion The colonization defect of the acxB:cat mutant suggests a role for the acxABC operon in survival of the bacterium in the stomach. Products of the H. pylori acxABC operon may function primarily in acetone utilization or may catalyze a related reaction that is important for survival or growth in the host. H. pylori encounters significant levels of acetone in the stomach which it could use as a potential electron donor for microaerobic respiration.

Visualizing changes in electron distribution in coupled chains of cytochrome bc(1) by modifying barrier for electron transfer between the FeS cluster and heme c(1).

Science.gov (United States)

Cieluch, Ewelina; Pietryga, Krzysztof; Sarewicz, Marcin; Osyczka, Artur

2010-02-01

Cytochrome c(1) of Rhodobacter (Rba.) species provides a series of mutants which change barriers for electron transfer through the cofactor chains of cytochrome bc(1) by modifying heme c(1) redox midpoint potential. Analysis of post-flash electron distribution in such systems can provide useful information about the contribution of individual reactions to the overall electron flow. In Rba. capsulatus, the non-functional low-potential forms of cytochrome c(1) which are devoid of the disulfide bond naturally present in this protein revert spontaneously by introducing a second-site suppression (mutation A181T) that brings the potential of heme c(1) back to the functionally high levels, yet maintains it some 100 mV lower from the native value. Here we report that the disulfide and the mutation A181T can coexist in one protein but the mutation exerts a dominant effect on the redox properties of heme c(1) and the potential remains at the same lower value as in the disulfide-free form. This establishes effective means to modify a barrier for electron transfer between the FeS cluster and heme c(1) without breaking disulfide. A comparison of the flash-induced electron transfers in native and mutated cytochrome bc(1) revealed significant differences in the post-flash equilibrium distribution of electrons only when the connection of the chains with the quinone pool was interrupted at the level of either of the catalytic sites by the use of specific inhibitors, antimycin or myxothiazol. In the non-inhibited system no such differences were observed. We explain the results using a kinetic model in which a shift in the equilibrium of one reaction influences the equilibrium of all remaining reactions in the cofactor chains. It follows a rather simple description in which the direction of electron flow through the coupled chains of cytochrome bc(1) exclusively depends on the rates of all reversible partial reactions, including the Q/QH2 exchange rate to/from the catalytic sites

Genetically Modified Bacteria for Fuel Production: Development of Rhodobacteria as a Versatile Platform for Fuels Production

Energy Technology Data Exchange (ETDEWEB)

None

2010-07-01

Electrofuels Project: Penn State is genetically engineering bacteria called Rhodobacter to use electricity or electrically generated hydrogen to convert carbon dioxide into liquid fuels. Penn State is taking genes from oil-producing algae called Botryococcus braunii and putting them into Rhodobacter to produce hydrocarbon molecules, which closely resemble gasoline. Penn State is developing engineered tanks to support microbial fuel production and determining the most economical way to feed the electricity or hydrogen to the bacteria, including using renewable sources of power like solar energy.

Spectral diffusion and electron-phonon coupling of the B800 BChl a molecules in LH2 complexes from three different species of purple bacteria.

Science.gov (United States)

Baier, J; Gabrielsen, M; Oellerich, S; Michel, H; van Heel, M; Cogdell, R J; Köhler, J

2009-11-04

We have investigated the spectral diffusion and the electron-phonon coupling of B800 bacteriochlorophyll a molecules in the peripheral light-harvesting complex LH2 for three different species of purple bacteria, Rhodobacter sphaeroides, Rhodospirillum molischianum, and Rhodopseudomonas acidophila. We come to the conclusion that B800 binding pockets for Rhodobacter sphaeroides and Rhodopseudomonas acidophila are rather similar with respect to the polarity of the protein environment but that the packaging of the alphabeta-polypeptides seems to be less tight in Rb. sphaeroides with respect to the other two species.

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

Mixing and mass transfer in a pilot scale U-loop bioreactor

DEFF Research Database (Denmark)

Petersen, Leander Adrian Haaning; Villadsen, John; Jørgensen, Sten Bay

2017-01-01

A system capable of handling a large volumetric gas fraction while providing a high gas to liquid mass transfer is a necessity if the metanotrophic bacterium Methylococcus capsulatus is to be used in single cell protein (SCP) production. In this study mixing time and mass transfer coefficients we...

Secretion of Flavins by Three Species of Methanotrophic Bacteria▿ †

OpenAIRE

Balasubramanian, Ramakrishnan; Levinson, Benjamin T.; Rosenzweig, Amy C.

2010-01-01

We detected flavins in the growth medium of the methanotrophic bacterium Methylocystis species strain M. Flavin secretion correlates with growth stage and increases under iron starvation conditions. Two other methanotrophs, Methylosinus trichosporium OB3b and Methylococcus capsulatus (Bath), secrete flavins, suggesting that flavin secretion may be common to many methanotrophic bacteria.

Microbial treatment of aqueous wastes

International Nuclear Information System (INIS)

Lee, Kang Suk; Chun, Ki Jung; Kim, Kug Chan; Choi, Yong Ho; Kim, Jin Kyu; Kim, In Gyu; Park, Hyo Koo; Lee, Keun Bae

1992-01-01

Uranium accumulated extracellularly on the surface of Rhodobacter capsulata and Rhodospirillum rubrum cells. The rate and extent accumulation were subject to environmental parameter such as pH, temperature, carbon source, trace element and interference by certain cations. Uranium accumulation by the cells was rapid and metabolism was not required for uranium uptake by both organism. Cell-bound uranium reached concentration of 22% (Rhodospirillum rubrum) and 24% (Rhdobacter capsulata)of the dry cell weight, but in the cells grown in the presence of inhibitory concentration of CoCl 2 , cell-bound uranium reached concentration of 27% (Rhodospirillum rubrum) and 29% (Rhodobacter capsulata) of dry cell weight. (Author)

The CoxD protein, a novel AAA+ ATPase involved in metal cluster assembly: hydrolysis of nucleotide-triphosphates and oligomerization.

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Tobias Maisel

Full Text Available CoxD of the α-proteobacterium Oligotropha carboxidovorans is a membrane protein which is involved in the posttranslational biosynthesis of the [CuSMoO₂] cluster in the active site of the enzyme CO dehydrogenase. The bacteria synthesize CoxD only in the presence of CO. Recombinant CoxD produced in E. coli K38 pGP1-2/pETMW2 appeared in inclusion bodies from where it was solubilized by urea and refolded by stepwise dilution. Circular dichroism spectroscopy revealed the presence of secondary structural elements in refolded CoxD. CoxD is a P-loop ATPase of the AAA-protein family. Refolded CoxD catalyzed the hydrolysis of MgATP yielding MgADP and inorganic phosphate at a 1∶1∶1 molar ratio. The reaction was inhibited by the slow hydrolysable MgATP-γ-S. GTPase activity of CoxD did not exceed 2% of the ATPase activity. Employing different methods (non linear regression, Hanes and Woolf, Lineweaver-Burk, preparations of CoxD revealed a mean K(M value of 0.69±0.14 mM ATP and an apparent V(max value of 19.3±2.3 nmol ATP hydrolyzed min⁻¹ mg⁻¹. Sucrose density gradient centrifugation and gel filtration showed that refolded CoxD can exist in various multimeric states (2-mer, 4-mer or 6-mer, preferentially as hexamer or dimer. Within weeks the hexamer dissociates into the dimer, a process which can be reversed by MgATP or MgATP-γ-S within hours. Only the hexamers and the dimers exhibited MgATPase activity. Transmission electron microscopy of negatively stained CoxD preparations revealed distinct particles within a size range of 10-16 nm, which further corroborates the oligomeric organization. The 3D structure of CoxD was modeled with the 3D structure of BchI from Rhodobacter capsulatus as template. It has the key elements of an AAA+ domain in the same arrangement and at same positions as in BchI and displays the characteristic inserts of the PS-II-insert clade. Possible functions of CoxD in [CuSMoO₂] cluster assembly are discussed.

Biosynthesis of caffeic acid in Escherichia coli using its endogenous hydroxylase complex

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Lin Yuheng

2012-04-01

Full Text Available Abstract Background Caffeic acid (3,4-dihydroxycinnamic acid is a natural phenolic compound derived from the plant phenylpropanoid pathway. Caffeic acid and its phenethyl ester (CAPE have attracted increasing attention for their various pharmaceutical properties and health-promoting effects. Nowadays, large-scale production of drugs or drug precursors via microbial approaches provides a promising alternative to chemical synthesis and extraction from plant sources. Results We first identified that an Escherichia coli native hydroxylase complex previously characterized as the 4-hydroxyphenylacetate 3-hydroxylase (4HPA3H was able to convert p-coumaric acid to caffeic acid efficiently. This critical enzymatic step catalyzed in plants by a membrane-associated cytochrome P450 enzyme, p-coumarate 3-hydroxylase (C3H, is difficult to be functionally expressed in prokaryotic systems. Moreover, the performances of two tyrosine ammonia lyases (TALs from Rhodobacter species were compared after overexpression in E. coli. The results indicated that the TAL from R. capsulatus (Rc possesses higher activity towards both tyrosine and L-dopa. Based on these findings, we further designed a dual pathway leading from tyrosine to caffeic acid consisting of the enzymes 4HPA3H and RcTAL. This heterologous pathway extended E. coli native tyrosine biosynthesis machinery and was able to produce caffeic acid (12.1 mg/L in minimal salt medium. Further improvement in production was accomplished by boosting tyrosine biosynthesis in E. coli, which involved the alleviation of tyrosine-induced feedback inhibition and carbon flux redirection. Finally, the titer of caffeic acid reached 50.2 mg/L in shake flasks after 48-hour cultivation. Conclusion We have successfully established a novel pathway and constructed an E. coli strain for the production of caffeic acid. This work forms a basis for further improvement in production, as well as opens the possibility of microbial synthesis

Microbial production of hydrogen from starch-manufacturing wastes

Energy Technology Data Exchange (ETDEWEB)

Yokoi, H.; Maki, R.; Hirose, J.; Hayashi, S. [Miyazaki Univ. (Japan). Dept. of Applied Chemistry

2002-05-01

Effective hydrogen production from starch-manufacturing wastes by microorganisms was investigated. Continuous hydrogen production in high yield of 2.7 mol H{sub 2} mol{sup -1} glucose was attained by a mixed culture of Clostridium butyricum and Enterobacter aerogenes HO-39 in the starch waste medium consisting of sweet potato starch residue as a carbon source and corn steep liquor as a nitrogen source in a repeated batch culture. Rhodobacter sp. M-19 could produce hydrogen from the supernatant of the culture broth obtained in the repeated batch culture of C. butyricum and E. aerogenes HO-39. Hydrogen yield of 4.5 mol H{sub 2} mol{sup -1} glucose was obtained by culturing Rhodobacter sp. M-19 in the supernatant supplemented with 20{mu}gl{sup -1} Na{sub 2}MoO{sub 4} 2H{sub 2}O and 10mgl{sup -1} EDTA in a repeated batch culture with pH control at 7.5. Therefore, continuous hydrogen production with total hydrogen yield of 7.2 mol H{sub 2} mol{sup -1} glucose from the starch remaining in the starch residue was attained by the repeated batch culture with C. butyricum and E. aerogenes HO-39 and by the successive repeated batch culture with Rhodobacter sp. M-19. (Author)

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

Profiling of ornithine lipids in bacterial extracts of Rhodobacter sphaeroides by reversed-phase liquid chromatography with electrospray ionization and multistage mass spectrometry (RPLC-ESI-MS(n)).

Science.gov (United States)

Granafei, Sara; Losito, Ilario; Trotta, Massimo; Italiano, Francesca; de Leo, Vincenzo; Agostiano, Angela; Palmisano, Francesco; Cataldi, Tommaso R I

2016-01-15

Ornithine lipids (OLs), a sub-group of the large (and of emerging interest) family of lipoamino acids of bacterial origin, contain a 3-hydroxy fatty acyl chain linked via an amide bond to the α-amino group of ornithine and via an ester bond to a second fatty acyl chain. OLs in extracts of Rhodobacter sphaeroides (R. sphaeroides) were investigated by high-performance reversed phase liquid chromatography (RPLC) with electrospray ionization mass spectrometry (ESI-MS) in negative ion mode using a linear ion trap (LIT). The presence of OLs bearing both saturated (i.e, 16:0, 17:0, 18:0, 19:0 and 20:0) and unsaturated chains (i.e., 18:1, 19:1, 19:2 and 20:1) was ascertained and their identification, even for isomeric, low abundance and partially co-eluting species, was achieved by low-energy collision induced dissociation (CID) multistage mass spectrometry (MS(n), n = 2-4). OLs signatures found in two R. sphaeroides strains, i.e., wild type 2.4.1 and mutant R26, were examined and up to 16 and 17 different OL species were successfully identified, respectively. OLs in both bacterial strains were characterized by several combinations of fatty chains on ester-linked and amide-linked 3-OH fatty acids. Multistage MS spectra of monoenoic amide-linked 3-OH acyl chains, allowed the identification of positional isomer of OL containing 18:1 (i.e. 9-octadecenoic) and 20:1 (i.e. 11-eicosenoic) fatty acids. The most abundant OL ([M-H](-) at m/z 717.5) in R. sphaeroides R26 was identified as OL 3-OH 20:1/19:1 (i.e., 3-OH-eicosenoic acid amide-linked to ornithine and esterified to a nonadecenoic chain containing a cyclopropane ring). An unusual OL (m/z 689.5 for the [M-H](-) ion), most likely containing a cyclopropene ester-linked acyl chain (i.e., OL 3-OH 18:0/19:2), was retrieved only in the carotenoidless mutant strain R26. Based on the biosynthetic pathways already known for cyclopropa(e)ne ring-including acyl chains, a plausible explanation was invoked for the enzymatic

NCBI nr-aa BLAST: CBRC-ATHA-01-0056 [SEVENS

Lifescience Database Archive (English)

Full Text Available CBRC-ATHA-01-0056 ref|YP_354669.1| ABC nitrate/sulfonate/bicarbonate transporter fa...mily, periplasmic substrate-binding protein [Rhodobacter sphaeroides 2.4.1] gb|ABA80768.1| ABC nitrate/sulfonate/bicarbonate

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.

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.

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.

Investigation of the effects of different carotenoids on the absorption and CD signals of light harvesting 1 complexes

NARCIS (Netherlands)

Georgakopoulou, S.; van der Zwan, G.; Olsen, J.D.; Hunter, C.N.; Niederman, R.A.; van Grondelle, R.

2006-01-01

Absorption and circular dichroism (CD) spectra of light-harvesting (LH)1 complexes from the purple bacteria Rhodobacter (Rba.) sphaeroides and Rhodospirillum (Rsp.) rubrum are presented. The complexes exhibit very low intensity, highly nonconservative, near-infrared (NIR) CD spectra. Absorption and

Long-Range Energy Propagation in Nanometer Arrays of Light Harvesting Antenna Complexes

NARCIS (Netherlands)

Escalantet, Maryana; Escalante Marun, M.; Lenferink, Aufrid T.M.; Zhao, Yiping; Tas, Niels Roelof; Huskens, Jurriaan; Hunter, C. Neil; Subramaniam, Vinod; Otto, Cornelis

2010-01-01

Here we report the first observation of long-range transport of excitation energy within a biomimetic molecular nanoarray constructed from LH2 antenna complexes from Rhodobacter sphaeroides. Fluorescence microscopy of the emission of light after local excitation with a diffraction-limited light beam

The genome of Methylobacillus flagellatus, the molecular basis forobligate methylotrophy, and the polyphyletic origin ofmethylotrophy

Energy Technology Data Exchange (ETDEWEB)

Chistoserdova, Ludmila; Lapidus, Alla; Han, Cliff; Goodwin,Lynne; Saunders, Liz; Brettin, Tom; Tapia, Roxanne; Gilna, Paul; Lucas,Susan; Richardson, Paul M.; Lidstrom, Mary E.

2007-01-08

Along with methane, methanol and methylated amines representimportant biogenic atmospheric constituents, thus not only methanotrophs,but also non-methanotrophic methylotrophs play a significant role inglobal carbon cycling. The complete genome of a model obligate methanoland methylamine utilizer, Methylobacillus flagellatus (strain KT) wassequenced. The genome is represented by a single circular chromosome ofapproximately 3 Mb pairs, potentially encoding a total of 2,766 proteins.Based on genome analysis as well as the results from previous genetic andmutational analyses, methylotrophy is enabled by methanol- andmethylamine dehydrogenases, the tetrahydromethanopterin-linkedformaldehyde oxidation pathway, the assimilatory and dissimilatorybranches of the ribulose monophosphate cycle, and by formatedehydrogenases. Some of the methylotrophy genes are present in more thanone (identical or non-identical) copy. The obligate dependence on singlecarbon compounds appears to be due to the incomplete tricarboxylic acidcycle, as no genes potentially encoding alpha ketoglutarate, malate orsuccinate dehydrogenases are identifiable. The genome of M. flagellatuswas compared, in terms of methylotrophy functions, to the previouslysequenced genomes of three methylotrophs: Methylobacterium extorquens(Alphaproteobacterium, 7 Mbp), Methylibium petroleophilum(Betaproteobacterium, 4 Mbp), and Methylococcus capsulatus(Gammaproteobacterium, 3.3 Mbp). Strikingly, metabolically and/orphylogenetically, methylotrophy functions in M. flagellatus were moresimilar to the ones in M. capsulatus and M. extorquens than to the onesin the more closely related M. petroleophilum, providing the firstgenomic evidence for the polyphyletic origin of methylotrophy inBetaproteobacteria.

The crystal structures of the tri-functional Chloroflexus aurantiacus and bi-functional Rhodobacter sphaeroides malyl-CoA lyases and comparison with CitE-like superfamily enzymes and malate synthases.

Science.gov (United States)

Zarzycki, Jan; Kerfeld, Cheryl A

2013-11-09

Malyl-CoA lyase (MCL) is a promiscuous carbon-carbon bond lyase that catalyzes the reversible cleavage of structurally related Coenzyme A (CoA) thioesters. This enzyme plays a crucial, multifunctional role in the 3-hydroxypropionate bi-cycle for autotrophic CO2 fixation in Chloroflexus aurantiacus. A second, phylogenetically distinct MCL from Rhodobacter sphaeroides is involved in the ethylmalonyl-CoA pathway for acetate assimilation. Both MCLs belong to the large superfamily of CitE-like enzymes, which includes the name-giving β-subunit of citrate lyase (CitE), malyl-CoA thioesterases and other enzymes of unknown physiological function. The CitE-like enzyme superfamily also bears sequence and structural resemblance to the malate synthases. All of these different enzymes share highly conserved catalytic residues, although they catalyze distinctly different reactions: C-C bond formation and cleavage, thioester hydrolysis, or both (the malate synthases). Here we report the first crystal structures of MCLs from two different phylogenetic subgroups in apo- and substrate-bound forms. Both the C. aurantiacus and the R. sphaeroides MCL contain elaborations on the canonical β8/α8 TIM barrel fold and form hexameric assemblies. Upon ligand binding, changes in the C-terminal domains of the MCLs result in closing of the active site, with the C-terminal domain of one monomer forming a lid over and contributing side chains to the active site of the adjacent monomer. The distinctive features of the two MCL subgroups were compared to known structures of other CitE-like superfamily enzymes and to malate synthases, providing insight into the structural subtleties that underlie the functional versatility of these enzymes. Although the C. aurantiacus and the R. sphaeroides MCLs have divergent primary structures (~37% identical), their tertiary and quaternary structures are very similar. It can be assumed that the C-C bond formation catalyzed by the MCLs occurs as proposed for

The lateral distance between a proton pump and ATP synthase determines the ATP-synthesis rate

Czech Academy of Sciences Publication Activity Database

Sjöholm, C.; Bergstrand, J.; Nilsson, T.; Šachl, Radek; von Ballmoos, Ch.; Widengren, J.; Brzezinski, P.

2017-01-01

Roč. 7, č. 1 (2017), č. článku 2926. ISSN 2045-2322 Institutional support: RVO:61388955 Keywords : biological energy -conversion * cytochrome-c-oxidase * membrane-surface * rhodobacter-sphaeroides Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 4.259, year: 2016

Role of charge-transfer states in bacterial photosynthesis

NARCIS (Netherlands)

Meech, S.R.; Hoff, A.J.

1986-01-01

Photon echo, photon-echo excitation, and "hole-burning" data recorded in the 800-990 nm region of Rhodobacter sphaeroides R26 and Rhodopseudomonas viridis reaction centers are reported. The primary process in these reaction centers, following excitation, was found to occur in ≈25 fsec; the

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

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

Photocycle of the flavin-binding photoreceptor AppA, a bacterial transcriptional antirepressor of photosynthesis genes

NARCIS (Netherlands)

Gauden, M.L.; Yeremenko, S.; Laan, W.; van Stokkum, I.H.M.; Ihalainen, J.A.; van Grondelle, R.; Hellingwerf, K.J.; Kennis, J.T.M.

2005-01-01

The flavoprotein AppA from Rhodobacter sphaeroides contains an N-terminal domain belonging to a new class of photoreceptors designated BLUF domains. AppA was shown to control photosynthesis gene expression in response to blue light and oxygen tension. We have investigated the photocycle of the AppA

Imaging of solid tumor using near-infrared emitting purple bacteria

International Nuclear Information System (INIS)

Moon, Sung Min; Min, Jung Joon; Kim, Sun A; Choy, Hyon E.; Bom, Hee Seung

2005-01-01

Rhodobacter sphaeroides 2.4.1 is α-3 purple nonsulfur eubacterium with an extensive metabolism. Under anaerobic conditions, it is able to grow by photosynthesis, respiration and fermentation. When grown photosynthetically, it uses wavelengths of light in the near-infrared and contains a reaction center that is the peripheral light-harvesting (LH2) complex. These molecules absorb and emit near-infrared light. Using this near-infrared fluorescent bacterial we investigated its targeting capacity of solid tumor in small animals. R. sphaeroides 2.4.1 strains were cultured in sistrons minimal medium A (SIS) at 32 C. Xenograft tumor model has been established by subcutaneous injection of CT26 mouse colon cancer cell line. 1X10 8 Rhodobacter sphaeroides cells suspended in 100 ul of PBS were injected via tail vein with 1-cc insulin syringe into tumor bearing mouse. In vivo fluorescence imaging has been done after 20 min to 30 days of purple bacteria using indocyanine (ICG) emission filter (Em=810∼835 nm). Near-infrared imaging signal from Rhodobacter sphaeroides was initially detected at liver for 3 days but at the necrotic region of tumor mass thereafter. Total photon flux measured 5.5X10 8 (p/s/cm 2 /sr) at Day 1. Also it was increased to 7.8X10 8 (p/s/cm 2 /sr) at 12 day. One of important characteristic is that the signal appeared only at central necrosis area. It has been monitored for 36 day. We successfully imaged cancer with near-infrared fluorescence bacteria. Our result indicate that near-infrared fluorescence purple bacteria are able to be used to monitor bacterial trafficking in living tumor models

Genome of Methylobacillus flagellatus, Molecular Basis for Obligate Methylotrophy, and Polyphyletic Origin of Methylotrophy

Energy Technology Data Exchange (ETDEWEB)

Chistoserdova, L; Lapidus, A; Han, C; Godwin, L; Saunders, L; Brettin, T; Tapia, R; Gilna, P; Lucas, S; Richardson, P M; Lidstrom, M E

2007-07-24

Along with methane, methanol and methylated amines represent important biogenic atmospheric constituents; thus, not only methanotrophs but also nonmethanotrophic methylotrophs play a significant role in global carbon cycling. The complete genome of a model obligate methanol and methylamine utilizer, Methylobacillus flagellatus (strain KT) was sequenced. The genome is represented by a single circular chromosome of approximately 3 Mbp, potentially encoding a total of 2,766 proteins. Based on genome analysis as well as the results from previous genetic and mutational analyses, methylotrophy is enabled by methanol and methylamine dehydrogenases and their specific electron transport chain components, the tetrahydromethanopterin-linked formaldehyde oxidation pathway and the assimilatory and dissimilatory ribulose monophosphate cycles, and by a formate dehydrogenase. Some of the methylotrophy genes are present in more than one (identical or nonidentical) copy. The obligate dependence on single-carbon compounds appears to be due to the incomplete tricarboxylic acid cycle, as no genes potentially encoding alpha-ketoglutarate, malate, or succinate dehydrogenases are identifiable. The genome of M. flagellatus was compared in terms of methylotrophy functions to the previously sequenced genomes of three methylotrophs, Methylobacterium extorquens (an alphaproteobacterium, 7 Mbp), Methylibium petroleiphilum (a betaproteobacterium, 4 Mbp), and Methylococcus capsulatus (a gammaproteobacterium, 3.3 Mbp). Strikingly, metabolically and/or phylogenetically, the methylotrophy functions in M. flagellatus were more similar to those in M. capsulatus and M. extorquens than to the ones in the more closely related M. petroleiphilum species, providing the first genomic evidence for the polyphyletic origin of methylotrophy in Betaproteobacteria.

GenBank blastx search result: AK061856 [KOME

Lifescience Database Archive (English)

Full Text Available AK061856 001-040-G03 AF018073.1 Rhodobacter sphaeroides operon regulator (smoC), periplasmic sorbitol...-binding protein (smoE), sorbitol/mannitol transport inner membrane protein (smoF), sorbitol.../mannitol transport inner membrane protein (smoG), sorbitol/mannitol transport ATP-binding transport protein (smoK), sorbitol

Conserved Chloroplast Open-reading Frame ycf54 Is Required for Activity of the Magnesium Protoporphyrin Monomethylester Oxidative Cyclase in Synechocystis PCC 6803

Czech Academy of Sciences Publication Activity Database

Hollingshead, S.; Kopečná, Jana; Jackson, P. J.; Canniffe, D. P.; Davidson, P. A.; Dickman, M. J.; Sobotka, Roman; Hunter, C. N.

2012-01-01

Roč. 287, č. 33 (2012), s. 27823-27833 ISSN 0021-9258 R&D Projects: GA ČR GAP501/10/1000; GA MŠk(CZ) ED2.1.00/03.0110 Institutional support: RVO:61388971 Keywords : CHLOROPHYLL ISOCYCLIC RING * RHODOBACTER-SPHAEROIDES * SP PCC-6803 Subject RIV: CE - Biochemistry Impact factor: 4.651, year: 2012

Continuous Cultivation of Photosynthetic Bacteria for Fatty Acids Production

DEFF Research Database (Denmark)

Kim, Dong-Hoon; Lee, Ji-Hye; Hwang, Yuhoon

2013-01-01

In the present work, we introduced a novel approach for microbial fatty acids (FA) production. Photosynthetic bacteria, Rhodobacter sphaeroides KD131, were cultivated in a continuous-flow, stirred-tank reactor (CFSTR) at various substrate (lactate) concentrations.At hydraulic retention time (HRT)....... sphaeroides was around 35% of dry cell weight, mainly composed of vaccenic acid (C18:1, omega-7)....

Effects of aeration and internal recycle flow on nitrous oxide emissions from a modified Ludzak-Ettinger process fed with glycerol.

Science.gov (United States)

Song, Kang; Suenaga, Toshikazu; Harper, Willie F; Hori, Tomoyuki; Riya, Shohei; Hosomi, Masaaki; Terada, Akihiko

2015-12-01

Nitrous oxide (N2O) is emitted from a modified Ludzak-Ettinger (MLE) process, as a primary activated sludge system, which requires mitigation. The effects of aeration rates and internal recycle flow (IRF) ratios on N2O emission were investigated in an MLE process fed with glycerol. Reducing the aeration rate from 1.5 to 0.5 L/min increased gaseous the N2O concentration from the aerobic tank and the dissolved N2O concentration in the anoxic tank by 54.4 and 53.4 %, respectively. During the period of higher aeration, the N2O-N conversion ratio was 0.9 % and the potential N2O reducers were predominantly Rhodobacter, which accounted for 21.8 % of the total population. Increasing the IRF ratio from 3.6 to 7.2 decreased the N2O emission rate from the aerobic tank and the dissolved N2O concentration in the anoxic tank by 56 and 48 %, respectively. This study suggests effective N2O mitigation strategies for MLE systems.

GenBank blastx search result: AK241729 [KOME

Lifescience Database Archive (English)

Full Text Available AK241729 J065199L10 AF018073.1 AF018073 Rhodobacter sphaeroides operon regulator (smoC), periplasmic sorbito...l-binding protein (smoE), sorbitol/mannitol transport inner membrane protein (smoF), sorbitol.../mannitol transport inner membrane protein (smoG), sorbitol/mannitol transport ATP-binding transport protein (smoK), sorbit...ol dehydrogenase (smoS), mannitol dehydrogenase (mtlK),

GenBank blastx search result: AK240874 [KOME

Lifescience Database Archive (English)

Full Text Available AK240874 J065025K09 AF018073.1 AF018073 Rhodobacter sphaeroides operon regulator (smoC), periplasmic sorbito...l-binding protein (smoE), sorbitol/mannitol transport inner membrane protein (smoF), sorbitol.../mannitol transport inner membrane protein (smoG), sorbitol/mannitol transport ATP-binding transport protein (smoK), sorbit...ol dehydrogenase (smoS), mannitol dehydrogenase (mtlK),

GenBank blastx search result: AK243680 [KOME

Lifescience Database Archive (English)

Full Text Available AK243680 J100090I20 AF018073.1 AF018073 Rhodobacter sphaeroides operon regulator (smoC), periplasmic sorbito...l-binding protein (smoE), sorbitol/mannitol transport inner membrane protein (smoF), sorbitol.../mannitol transport inner membrane protein (smoG), sorbitol/mannitol transport ATP-binding transport protein (smoK), sorbit...ol dehydrogenase (smoS), mannitol dehydrogenase (mtlK),

Biodegradation of Various Aromatic Compounds by Enriched Bacterial Cultures: Part A-Monocyclic and Polycyclic Aromatic Hydrocarbons.

Science.gov (United States)

Oberoi, Akashdeep Singh; Philip, Ligy; Bhallamudi, S Murty

2015-08-01

Present study focused on the screening of bacterial consortium for biodegradation of monocyclic aromatic hydrocarbon (MAH) and polycyclic aromatic hydrocarbons (PAHs). Target compounds in the present study were naphthalene, acenaphthene, phenanthrene (PAHs), and benzene (MAH). Microbial consortia enriched with the above target compounds were used in screening experiments. Naphthalene-enriched consortium was found to be the most efficient consortium, based on its substrate degradation rate and its ability to degrade other aromatic pollutants with significantly high efficiency. Substrate degradation rate with naphthalene-enriched culture followed the order benzene > naphthalene > acenaphthene > phenanthrene. Chryseobacterium and Rhodobacter were discerned as the predominant species in naphthalene-enriched culture. They are closely associated to the type strain Chryseobacterium arthrosphaerae and Rhodobacter maris, respectively. Single substrate biodegradation studies with naphthalene (PAH) and benzene (MAH) were carried out using naphthalene-enriched microbial consortium (NAPH). Phenol and 2-hydroxybenzaldehyde were identified as the predominant intermediates during benzene and naphthalene degradation, respectively. Biodegradation of toluene, ethyl benzene, xylene, phenol, and indole by NAPH was also investigated. Monod inhibition model was able to simulate biodegradation kinetics for benzene, whereas multiple substrate biodegradation model was able to simulate biodegradation kinetics for naphthalene.

Microbiological Hydrogen Production by Anaerobic Fermentation and Photosynthetic Process

International Nuclear Information System (INIS)

Asada, Y.; Ohsawa, M.; Nagai, Y.; Fukatsu, M.; Ishimi, K.; Ichi-ishi, S.

2009-01-01

Hydrogen gas is a clean and renewable energy carrier. Microbiological hydrogen production from glucose or starch by combination used of an anaerobic fermenter and a photosynthetic bacterium, Rhodobacter spheroides RV was studied. In 1984, the co-culture of Clostridium butyricum and RV strain to convert glucose to hydrogen was demonstrated by Miyake et al. Recently, we studied anaerobic fermentation of starch by a thermophilic archaea. (Author)

Membrane Curvature Induced by Aggregates of LH2s and Monomeric LH1s

OpenAIRE

Chandler, Danielle E.; Gumbart, James; Stack, John D.; Chipot, Christophe; Schulten, Klaus

2009-01-01

The photosynthetic apparatus of purple bacteria is contained within organelles called chromatophores, which form as extensions of the cytoplasmic membrane. The shape of these chromatophores can be spherical (as in Rhodobacter sphaeroides), lamellar (as in Rhodopseudomonas acidophila and Phaeospirillum molischianum), or tubular (as in certain Rb. sphaeroides mutants). Chromatophore shape is thought to be influenced by the integral membrane proteins Light Harvesting Complexes I and II (LH1 and ...

Visualizing tributyltin (TBT) in bacterial aggregates by specific rhodamine-based fluorescent probes.

Science.gov (United States)

Jin, Xilang; Hao, Likai; She, Mengyao; Obst, Martin; Kappler, Andreas; Yin, Bing; Liu, Ping; Li, Jianli; Wang, Lanying; Shi, Zhen

2015-01-01

Here we present the first examples of fluorescent and colorimetric probes for microscopic TBT imaging. The fluorescent probes are highly selective and sensitive to TBT and have successfully been applied for imaging of TBT in bacterial Rhodobacter ferrooxidans sp. strain SW2 cell-EPS-mineral aggregates and in cell suspensions of the marine cyanobacterium Synechococcus PCC 7002 by using confocal laser scanning microscopy. Copyright © 2014 Elsevier B.V. All rights reserved.

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....

Data in support of intermolecular interactions at early stage of protein/detergent particle association induced by salt/polyethylene glycol mixtures

Directory of Open Access Journals (Sweden)

Takayuki Odahara

2016-06-01

Full Text Available The data provide information in support of the research article, “Intermolecular interactions at early stage of protein/detergent particle association induced by salt/polyethylene glycol mixtures” [1]. The data regarding variation of absorption spectra is used as an indicator of the duration of Rp. viridis PRU and RC, Rb. sphaeroides RC and LH2, and Rb. capsulatus LH2 in the native state in the presence of NaCl/polyethylene glycol (PEG mixture. The data about minimum concentrations of salt and PEG whose aqueous phases are mutually separated presents information on additional influence of Tris buffer and N-octyl-β-d-glucoside on the salt–PEG phase separation.

Evaluation of methane-utilising bacteria products as feed ingredients for monogastric animals

DEFF Research Database (Denmark)

Øverland, Margareth; Tauson, Anne-Helene; Shearer, Karl

2010-01-01

ingredients for animals. We present results from earlier work and recent findings concerning bacterial protein, including the production process, chemical composition, effects on nutrient digestibility, metabolism, and growth performance in several monogastric species, including pigs, broiler chickens, mink......Bacterial proteins represent a potential future nutrient source for monogastric animal production because they can be grown rapidly on substrates with minimum dependence on soil, water, and climate conditions. This review summarises the current knowledge on methane-utilising bacteria as feed...... Methylococcus capsulatus (Bath), is a promising source of protein based on criteria such as amino acid composition, digestibility, and animal performance and health. Future research challenges include modified downstream processing to produce value-added products, and improved understanding of factors...

The microorganisms as a renewable source of ecological clean fuel

International Nuclear Information System (INIS)

Shalygo, N.V.; Mel'nikov, S.S.; Manankina, E.E.; Budakova, E.A.; Kolyago, V.M.

2006-01-01

Five families of microorganisms (Bacillaceae, Rhodospirillaceae, Cyanophyceae, Chlorophyceae and Euglenophyceae) as hydrogen producers were tested and the conditions that are necessary for hydrogen photoproduction were investigated. It was shown, that the most effective producers of hydrogen were Rhodobacter spheroides, Clostridium sp.; Euglena gracilis var. bacillaris and Chlamydomonas reinhardtii. Addition of glucose, iron and vanadium salts resulted in the increase of hydrogen production. Polycultures consisted of two or three microorganisms were more effective hydrogen producers compared to separate monocultures. (authors)

Interaction of two photoreceptors in the regulation of bacterial photosynthesis genes

OpenAIRE

Metz, Sebastian; Haberzettl, Kerstin; Frühwirth, Sebastian; Teich, Kristin; Hasewinkel, Christian; Klug, Gabriele

2012-01-01

The expression of photosynthesis genes in the facultatively photosynthetic bacterium Rhodobacter sphaeroides is controlled by the oxygen tension and by light quantity. Two photoreceptor proteins, AppA and CryB, have been identified in the past, which are involved in this regulation. AppA senses light by its N-terminal BLUF domain, its C-terminal part binds heme and is redox-responsive. Through its interaction to the transcriptional repressor PpsR the AppA photoreceptor controls expression of ...

Reduced Rank Regression

DEFF Research Database (Denmark)

Johansen, Søren

2008-01-01

The reduced rank regression model is a multivariate regression model with a coefficient matrix with reduced rank. The reduced rank regression algorithm is an estimation procedure, which estimates the reduced rank regression model. It is related to canonical correlations and involves calculating...

Engineered photoproteins that give rise to photosynthetically-incompetent bacteria are effective as photovoltaic materials for biohybrid photoelectrochemical cells.

Science.gov (United States)

Liu, Juntai; Friebe, Vincent M; Swainsbury, David J K; Crouch, Lucy I; Szabo, David A; Frese, Raoul N; Jones, Michael R

2018-04-17

Reaction centre/light harvesting proteins such as the RCLH1X complex from Rhodobacter sphaeroides carry out highly quantum-efficient conversion of solar energy through ultrafast energy transfer and charge separation, and these pigment-proteins have been incorporated into biohybrid photoelectrochemical cells for a variety of applications. In this work we demonstrate that, despite not being able to support normal photosynthetic growth of Rhodobacter sphaeroides, an engineered variant of this RCLH1X complex lacking the PufX protein and with an enlarged light harvesting antenna is unimpaired in its capacity for photocurrent generation in two types of bio-photoelectrochemical cells. Removal of PufX also did not impair the ability of the RCLH1 complex to act as an acceptor of energy from synthetic light harvesting quantum dots. Unexpectedly, the removal of PufX led to a marked improvement in the overall stability of the RCLH1 complex under heat stress. We conclude that PufX-deficient RCLH1 complexes are fully functional in solar energy conversion in a device setting and that their enhanced structural stability could make them a preferred choice over their native PufX-containing counterpart. Our findings on the competence of RCLH1 complexes for light energy conversion in vitro are discussed with reference to the reason why these PufX-deficient proteins are not capable of light energy conversion in vivo.

Review of pump suction reducer selection: Eccentric or concentric reducers

OpenAIRE

Mahaffey, R M; van Vuuren, S J

2014-01-01

Eccentric reducers are traditionally recommended for the pump suction reducer fitting to allow for transportation of air through the fitting to the pump. The ability of a concentric reducer to provide an improved approach flow to the pump while still allowing air to be transported through the fitting is investigated. Computational fluid dynamics (CFD) were utilised to analyse six concentric and six eccentric reducer geometries at four different inlet velocities to determine the flow velocity ...

The effect of design and scale on the mixing and mass transfer in U-loop bioreactors

DEFF Research Database (Denmark)

Petersen, Leander Adrian Haaning; Villadsen, John; Jørgensen, Sten Bay

is altered? In this study we have investigated the mixing time and mass transfer capabilities of U-loop reactors of different geometries (high vs. diameter ratio) in pilot (0.15m3) and semi-industrial scales (2.2m3). A new expression for the mechanical power input into the system is also proposed, which......A system capable of handling a large volumetric gas fraction while providing a high gas to liquid mass transfer is a necessity if the metanotrophic bacterium Methylococcus capsulatus is to be used in single cell protein (SCP) production. Previous studies have proven that a U-loop fermenter, a novel...... indicates that an even more favorable relationship between power input and mass transfer rate (compared to previous literature) applies to U-loop fermenters....

Distinguishing iron-reducing from sulfate-reducing conditions

Science.gov (United States)

Chapelle, F.H.; Bradley, P.M.; Thomas, M.A.; McMahon, P.B.

2009-01-01

Ground water systems dominated by iron- or sulfate-reducing conditions may be distinguished by observing concentrations of dissolved iron (Fe2+) and sulfide (sum of H2S, HS-, and S= species and denoted here as "H2S"). This approach is based on the observation that concentrations of Fe2+ and H2S in ground water systems tend to be inversely related according to a hyperbolic function. That is, when Fe2+ concentrations are high, H2S concentrations tend to be low and vice versa. This relation partly reflects the rapid reaction kinetics of Fe2+ with H2S to produce relatively insoluble ferrous sulfides (FeS). This relation also reflects competition for organic substrates between the iron- and the sulfate-reducing microorganisms that catalyze the production of Fe2+ and H 2S. These solubility and microbial constraints operate in tandem, resulting in the observed hyperbolic relation between Fe2+ and H 2S concentrations. Concentrations of redox indicators, including dissolved hydrogen (H2) measured in a shallow aquifer in Hanahan, South Carolina, suggest that if the Fe2+/H2S mass ratio (units of mg/L) exceeded 10, the screened interval being tapped was consistently iron reducing (H2 ???0.2 to 0.8 nM). Conversely, if the Fe 2+/H2S ratio was less than 0.30, consistent sulfate-reducing (H2 ???1 to 5 nM) conditions were observed over time. Concomitantly high Fe2+ and H2S concentrations were associated with H2 concentrations that varied between 0.2 and 5.0 nM over time, suggesting mixing of water from adjacent iron- and sulfate-reducing zones or concomitant iron and sulfate reduction under nonelectron donor-limited conditions. These observations suggest that Fe2+/H2S mass ratios may provide useful information concerning the occurrence and distribution of iron and sulfate reduction in ground water systems. ?? 2009 National Ground Water Association.

Learning to REDUCE: A Reduced Electricity Consumption Prediction Ensemble

Energy Technology Data Exchange (ETDEWEB)

Aman, Saima; Chelmis, Charalampos; Prasanna, Viktor

2016-02-12

Utilities use Demand Response (DR) to balance supply and demand in the electric grid by involving customers in efforts to reduce electricity consumption during peak periods. To implement and adapt DR under dynamically changing conditions of the grid, reliable prediction of reduced consumption is critical. However, despite the wealth of research on electricity consumption prediction and DR being long in practice, the problem of reduced consumption prediction remains largely un-addressed. In this paper, we identify unique computational challenges associated with the prediction of reduced consumption and contrast this to that of normal consumption and DR baseline prediction.We propose a novel ensemble model that leverages different sequences of daily electricity consumption on DR event days as well as contextual attributes for reduced consumption prediction. We demonstrate the success of our model on a large, real-world, high resolution dataset from a university microgrid comprising of over 950 DR events across a diverse set of 32 buildings. Our model achieves an average error of 13.5%, an 8.8% improvement over the baseline. Our work is particularly relevant for buildings where electricity consumption is not tied to strict schedules. Our results and insights should prove useful to the researchers and practitioners working in the sustainable energy domain.

Defluviimonas denitrificans gen. nov., sp. nov., and Pararhodobacter aggregans gen. nov., sp. nov., non-phototrophic Rhodobacteraceae from the biofilter of a marine aquaculture

DEFF Research Database (Denmark)

Foesel, Bärbel U.; Drake, Harold L.; Schramm, Andreas

2011-01-01

Three Gram-negative bacterial strains were isolated from the biofilter of a recirculating marine aquaculture. They were non-pigmented rods, mesophiles, moderately halophilic, and showed chemoorganoheterotrophic growth on various sugars, fatty acids, and amino acids, with oxygen as electron acceptor......, but clearly separate from, the genera Rhodobacter, Rhodovulum, and Rhodobaca. Based on morphological, physiological, and 16S rRNA-based phylogenetic characteristics, the isolated strains are proposed as new species of two novel genera, Defluviimonas denitrificans gen. nov., sp. nov. (type strain D9-3T = DSM...

NifH and NifD phylogenies: an evolutionary basis for understanding nitrogen fixation capabilities of methanotrophic bacteria.

Science.gov (United States)

Dedysh, Svetlana N; Ricke, Peter; Liesack, Werner

2004-05-01

The ability to utilize dinitrogen as a nitrogen source is an important phenotypic trait in most currently known methanotrophic bacteria (MB). This trait is especially important for acidophilic MB, which inhabit acidic oligotrophic environments, highly depleted in available nitrogen compounds. Phylogenetically, acidophilic MB are most closely related to heterotrophic dinitrogen-fixing bacteria of the genus BEIJERINCKIA: To further explore the phylogenetic linkage between these metabolically different organisms, the sequences of nifH and nifD gene fragments from acidophilic MB of the genera Methylocella and Methylocapsa, and from representatives of Beijerinckia, were determined. For reference, nifH and nifD sequences were also obtained from some type II MB of the alphaproteobacterial Methylosinus/Methylocystis group and from gammaproteobacterial type I MB. The trees constructed for the inferred amino acid sequences of nifH and nifD were highly congruent. The phylogenetic relationships among MB in the NifH and NifD trees also agreed well with the corresponding 16S rRNA-based phylogeny, except for two distinctive features. First, different methods used for phylogenetic analysis grouped the NifH and NifD sequences of strains of the gammaproteobacterial MB Methylococcus capsulatus within a clade mainly characterized by Alphaproteobacteria, including acidophilic MB and type II MB of the Methylosinus/Methylocystis group. From this and other genomic data from Methylococcus capsulatus Bath, it is proposed that an ancient event of lateral gene transfer was responsible for this aberrant branching. Second, the identity values of NifH and NifD sequences between Methylocapsa acidiphila B2 and representatives of Beijerinckia were clearly higher (98.5 and 96.6 %, respectively) than would be expected from their 16S rRNA-based relationships. Possibly, these two bacteria originated from a common acidophilic dinitrogen-fixing ancestor, and were subject to similar evolutionary pressure

Coupling of anaerobic waste treatment to produce protein- and lipid-rich bacterial biomass

Science.gov (United States)

Steinberg, Lisa M.; Kronyak, Rachel E.; House, Christopher H.

2017-11-01

Future long-term manned space missions will require effective recycling of water and nutrients as part of a life support system. Biological waste treatment is less energy intensive than physicochemical treatment methods, yet anaerobic methanogenic waste treatment has been largely avoided due to slow treatment rates and safety issues concerning methane production. However, methane is generated during atmosphere regeneration on the ISS. Here we propose waste treatment via anaerobic digestion followed by methanotrophic growth of Methylococcus capsulatus to produce a protein- and lipid-rich biomass that can be directly consumed, or used to produce other high-protein food sources such as fish. To achieve more rapid methanogenic waste treatment, we built and tested a fixed-film, flow-through, anaerobic reactor to treat an ersatz wastewater. During steady-state operation, the reactor achieved a 97% chemical oxygen demand (COD) removal rate with an organic loading rate of 1740 g d-1 m-3 and a hydraulic retention time of 12.25 d. The reactor was also tested on three occasions by feeding ca. 500 g COD in less than 12 h, representing 50x the daily feeding rate, with COD removal rates ranging from 56-70%, demonstrating the ability of the reactor to respond to overfeeding events. While investigating the storage of treated reactor effluent at a pH of 12, we isolated a strain of Halomonas desiderata capable of acetate degradation under high pH conditions. We then tested the nutritional content of the alkaliphilic Halomonas desiderata strain, as well as the thermophile Thermus aquaticus, as supplemental protein and lipid sources that grow in conditions that should preclude pathogens. The M. capsulatus biomass consisted of 52% protein and 36% lipids, the H. desiderata biomass consisted of 15% protein and 7% lipids, and the Thermus aquaticus biomass consisted of 61% protein and 16% lipids. This work demonstrates the feasibility of rapid waste treatment in a compact reactor design

Pipeline Drag Reducers

International Nuclear Information System (INIS)

Marawan, H.

2004-01-01

Pipeline drag reducers have proven to be an extremely powerful tool in fluid transportation. High molecular weight polymers are used to reduce the frictional pressure loss ratio in crude oil pipelines, refined fuel and aqueous pipelines. Chemical structure of the main used pipeline drag reducers is one of the following polymers and copolymers classified according to the type of fluid to ; low density polyethylene, copolymer of I-hexane cross linked with divinyl benzene, polyacrylamide, polyalkylene oxide polymers and their copolymers, fluorocarbons, polyalkyl methacrylates and terpolymer of styrene, alkyl acrylate and acrylic acid. Drag reduction is the increase in pump ability of a fluid caused by the addition of small amounts of an additive to the fluid. The effectiveness of a drag reducer is normally expressed in terms of percent drag reduction. Frictional pressure loss in a pipeline system is a waste of energy and it costly. The drag reducing additive minimizes the flow turbulence, increases throughput and reduces the energy costs. The Flow can be increased by more than 80 % with existing assets. The effectiveness of the injected drag reducer in Mostorod to Tanta crude oil pipeline achieved 35.4 % drag reduction and 23.2 % flow increase of the actual performance The experimental application of DRA on Arab Petroleum Pipeline Company (Summed) achieved a flow increase ranging from 9-32 %

Molecular Regulation of Photosynthetic Carbon Dioxide Fixation in Nonsulfur Purple Bacteria

Energy Technology Data Exchange (ETDEWEB)

Tabita, Fred Robert [The Ohio State Univ., Columbus, OH (United States)

2015-12-01

The overall objective of this project is to determine the mechanism by which a transcriptional activator protein affects CO₂ fixation (cbb) gene expression in nonsulfur purple photosynthetic bacteria, with special emphasis to Rhodobacter sphaeroides and with comparison to Rhodopseudomonas palustris. These studies culminated in several publications which indicated that additional regulators interact with the master regulator CbbR in both R. sphaeroides and R. palustris. In addition, the interactive control of the carbon and nitrogen assimilatory pathways was studied and unique regulatory signals were discovered.

Antagonistic Activities of Purple Non-sulfur Bacterial Extracts Against Antibiotic Resistant Vibrio sp.

Directory of Open Access Journals (Sweden)

Chandrasekaran, R.

2011-01-01

Full Text Available Solvent extracts of native purple non-sulfur bacterial (PNSB isolates from the effluents of brackish shrimp culture ponds, near Nagapattinam coast (South India were evaluated for antibacterial activity by the disc diffusion method. Best results were shown by the chloroform extracts against oxytetracycline resistant Vibrio harveyi and Vibrio fischerii. Among the purple non-sulfur bacterial isolates, Rhodobacter sphaeroides, showed maximum antagonistic activity. The findings suggest that the antagonistic extracts from Rba. sphaeroides could be used as an effective antibiotic in controlling Vibrio spp., in aquaculture systems.

Thermal properties of graphite oxide, thermally reduced graphene and chemically reduced graphene

Science.gov (United States)

Jankovský, Ondřej; Sedmidubský, David; Lojka, Michal; Sofer, Zdeněk

2017-07-01

We compared thermal behavior and other properties of graphite oxide, thermally reduced graphene and chemically reduced graphene. Graphite was oxidized according to the Hofmann method using potassium chlorate as oxidizing agent in strongly acidic environment. In the next step, the formed graphite oxide was chemically or thermally reduced yielding graphene. The mechanism of thermal reduction was studied using STA-MS. Graphite oxide and both thermally and chemically reduced graphenes were analysed by SEM, EDS, elemental combustion analysis, XPS, Raman spectroscopy, XRD and BET. These findings will help for the large scale production of graphene with appropriate chemical composition.

Reduced abrasion drilling fluid

NARCIS (Netherlands)

2010-01-01

A reduced abrasion drilling fluid system and method of drilling a borehole by circulating the reduced abrasion drilling fluid through the borehole is disclosed. The reduced abrasion drilling fluid comprises a drilling fluid, a first additive and a weighting agent, wherein the weighting agent has a

Reduced abrasion drilling fluid

NARCIS (Netherlands)

2012-01-01

A reduced abrasion drilling fluid system and method of drilling a borehole by circulating the reduced abrasion drilling fluid through the borehole is disclosed. The reduced abrasion drilling fluid comprises a drilling fluid, a first additive and a weighting agent, wherein the weighting agent has a

Direct oxide reducing method

International Nuclear Information System (INIS)

Tokiwai, Moriyasu.

1995-01-01

Calcium oxides and magnetic oxides as wastes generated upon direct reduction are subjected to molten salt electrolysis, and reduced metallic calcium and magnesium are separated and recovered. Then calcium and magnesium are used recyclically as the reducing agent upon conducting direct oxide reduction. Even calcium oxides and magnesium oxides, which have high melting points and difficult to be melted usually, can be melted in molten salts of mixed fluorides or chlorides by molten-salt electrolysis. Oxides are decomposed by electrolysis, and oxygen is removed in the form of carbon monoxide, while the reduced metallic calcium and magnesium rise above the molten salts on the side of a cathode, and then separated. Since only carbon monoxide is generated as radioactive wastes upon molten salt electrolysis, the amount of radioactive wastes can be greatly reduced, and the amount of the reducing agent used can also be decreased remarkably. (N.H.)

Directed assembly of functional light harvesting antenna complexes onto chemically patterned surfaces

International Nuclear Information System (INIS)

Escalante, Maryana; Maury, Pascale; Bruinink, Christiaan M; Werf, Kees van der; Olsen, John D; Timney, John A; Huskens, Jurriaan; Hunter, C Neil; Subramaniam, Vinod; Otto, Cees

2008-01-01

We report the directed assembly of the photosynthetic membrane proteins LH1 and LH2 isolated from the purple bacterium Rhodobacter sphaeroides onto chemically patterned substrates. Nanoimprint lithography was used to pattern discrete regions of amino- and fluoro-terminated or poly(ethylene glycol) self-assembled monolayers onto a glass substrate. Densely packed layers of assembled protein complexes were observed with atomic force microscopy. The protein complexes attached selectively to the amino-terminated regions by electrostatic interactions. Spectral images generated with a hybrid scanning probe and fluorescence microscope confirmed that the patterned proteins retained their native optical signatures

Directed assembly of functional light harvesting antenna complexes onto chemically patterned surfaces

Energy Technology Data Exchange (ETDEWEB)

Escalante, Maryana [Biophysical Engineering Group, MESA and Institute for Nanotechnology, University of Twente, PO Box 217, 7500 AE Enschede (Netherlands); Maury, Pascale [Molecular Nanofabrication Group, MESA and Institute for Nanotechnology, University of Twente, PO Box 217, 7500 AE Enschede (Netherlands); Bruinink, Christiaan M [Molecular Nanofabrication Group, MESA and Institute for Nanotechnology, University of Twente, PO Box 217, 7500 AE Enschede (Netherlands); Werf, Kees van der [Biophysical Engineering Group, MESA and Institute for Nanotechnology, University of Twente, PO Box 217, 7500 AE Enschede (Netherlands); Olsen, John D [Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN (United Kingdom); Timney, John A [Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN (United Kingdom); Huskens, Jurriaan [Molecular Nanofabrication Group, MESA and Institute for Nanotechnology, University of Twente, PO Box 217, 7500 AE Enschede (Netherlands); Hunter, C Neil [Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN (United Kingdom); Subramaniam, Vinod [Biophysical Engineering Group, MESA and Institute for Nanotechnology, University of Twente, PO Box 217, 7500 AE Enschede (Netherlands); Otto, Cees [Biophysical Engineering Group, MESA and Institute for Nanotechnology, University of Twente, PO Box 217, 7500 AE Enschede (Netherlands)

2008-01-16

We report the directed assembly of the photosynthetic membrane proteins LH1 and LH2 isolated from the purple bacterium Rhodobacter sphaeroides onto chemically patterned substrates. Nanoimprint lithography was used to pattern discrete regions of amino- and fluoro-terminated or poly(ethylene glycol) self-assembled monolayers onto a glass substrate. Densely packed layers of assembled protein complexes were observed with atomic force microscopy. The protein complexes attached selectively to the amino-terminated regions by electrostatic interactions. Spectral images generated with a hybrid scanning probe and fluorescence microscope confirmed that the patterned proteins retained their native optical signatures.

Oxygen-reducing catalyst layer

Science.gov (United States)

O'Brien, Dennis P [Maplewood, MN; Schmoeckel, Alison K [Stillwater, MN; Vernstrom, George D [Cottage Grove, MN; Atanasoski, Radoslav [Edina, MN; Wood, Thomas E [Stillwater, MN; Yang, Ruizhi [Halifax, CA; Easton, E Bradley [Halifax, CA; Dahn, Jeffrey R [Hubley, CA; O'Neill, David G [Lake Elmo, MN

2011-03-22

An oxygen-reducing catalyst layer, and a method of making the oxygen-reducing catalyst layer, where the oxygen-reducing catalyst layer includes a catalytic material film disposed on a substrate with the use of physical vapor deposition and thermal treatment. The catalytic material film includes a transition metal that is substantially free of platinum. At least one of the physical vapor deposition and the thermal treatment is performed in a processing environment comprising a nitrogen-containing gas.

Reducing infant mortality.

Science.gov (United States)

Johnson, T R

1994-01-01

Public health and social policies at the population level (e.g., oral rehydration therapy and immunization) are responsible for the major reduction in infant mortality worldwide. The gap in infant mortality rates between developing and developed regions is much less than that in maternal mortality rates. This indicates that maternal and child health (MCH) programs and women's health care should be combined. Since 1950, 66% of infant deaths occur in the 1st 28 days, indicating adverse prenatal and intrapartum events (e.g., congenital malformation and birth injuries). Infection, especially pneumonia and diarrhea, and low birth weight are the major causes of infant mortality worldwide. An estimated US$25 billion are needed to secure the resources to control major childhood diseases, reduce malnutrition 50%, reduce child deaths by 4 million/year, provide potable water and sanitation to all communities, provide basic education, and make family planning available to all. This cost for saving children's lives is lower than current expenditures for cigarettes (US$50 billion in Europe/year). Vitamin A supplementation, breast feeding, and prenatal diagnosis of congenital malformations are low-cost strategies that can significantly affect infant well-being and reduce child mortality in many developing countries. The US has a higher infant mortality rate than have other developed countries. The American College of Obstetricians and Gynecologists and the US National Institutes of Health are focusing on prematurity, low birth weight, multiple pregnancy, violence, alcohol abuse, and poverty to reduce infant mortality. Obstetricians should be important members of MCH teams, which also include traditional birth attendants, community health workers, nurses, midwives, and medical officers. We have the financial resources to allocate resources to improve MCH care and to reduce infant mortality.

Reducible oxide based catalysts

Science.gov (United States)

Thompson, Levi T.; Kim, Chang Hwan; Bej, Shyamal K.

2010-04-06

A catalyst is disclosed herein. The catalyst includes a reducible oxide support and at least one noble metal fixed on the reducible oxide support. The noble metal(s) is loaded on the support at a substantially constant temperature and pH.

Effects of Glasswort (Salicornia herbacea L.) Hydrates on Quality Characteristics of Reduced-salt, Reduced-fat Frankfurters

Science.gov (United States)

Choi, Yun-Sang

2015-01-01

This study evaluated the effects of adding glasswort hydrate containing non-meat ingredient (GM, carboxy methyl cellulose; GC, carrageenan; GI, isolated soy protein; GS, sodium caseinate) on the quality characteristics of reduced-salt, reduced-fat frankfurters. The pH and color evaluation showed significant differences, depending on the type of glasswort hydrate added (p<0.05). In the raw batters and cooked frankfurters, the addition of glasswort hydrate decreased the redness and increased the yellowness in comparison with frankfurters without glasswort hydrate. The reduction in salt and fat content significantly increased cooking loss and decreased hardness, tenderness and juiciness (p<0.05). Glasswort hydrate containing non-meat ingredient improved cooking loss, water holding capacity, emulsion stability, hardness, and viscosity of reduced-salt, reduced-fat frankfurters. The GM treatment had the highest myofibiliar protein solubility among all treatments, which was associated with emulsion stability and viscosity. The GC treatment had higher values for all texture parameters than the control. In the sensory evaluation, the addition of glasswort hydrate with non-meat ingredient improved tenderness and juiciness of reduced-salt, reduced-fat frankfurters. GM, GC, and GI treatments improved not only the physicochemical properties but also the sensory characteristics of reduced-salt, reduced-fat frankfurters. The results indicated that the use of glasswort hydrate containing non-meat ingredient was improved the quality characteristics of reduced-salt, reduced-fat frankfurters. PMID:26877638

Reducing costs by reducing size

International Nuclear Information System (INIS)

Hayns, M.R.; Shepherd, J.

1991-01-01

The present paper discusses briefly the many factors, including capital cost, which have to be taken into account in determining whether a series of power stations based on a small nuclear plant can be competitive with a series based on traditional large unit sizes giving the guaranteed level of supply. The 320 MWe UK/US Safe Integral Reactor is described as a good example of how the factors discussed can be beneficially incorporated into a design using proven technology. Finally it goes on to illustrate how the overall costs of a generating system can indeed by reduced by use of the 320 MWe Safe Integral Reactor rather than conventional units of around 1200 MWe. (author). 9 figs

Endogenous mobility-reducing norms

NARCIS (Netherlands)

Haagsma, R.; Koning, N.B.J.

2002-01-01

We present a model where a mobility-reducing norm arises in response to adverse economic conditions. Our example is the classical farm problem of low returns. A temporary transition barrier induces cognitive dissonance in farm youths, which they try to reduce by developing a belief that revalues

Shrinkage Reducing Admixture for Concrete

OpenAIRE

ECT Team, Purdue

2007-01-01

Concrete shrinkage cracking is a common problem in all types of concrete structures, especially for structures and environments where the cracks are prevalent and the repercussions are most severe. A liquid shrinkage reducing admixture for concrete, developed by GRACE Construction Products and ARCO Chemical Company, that reduces significantly the shrinkage during concrete drying and potentially reduces overall cracking over time.

Self-trapped excitons in LH2 bacteriochlorophyll-protein complexes under high pressure

International Nuclear Information System (INIS)

Timpmann, K.; Ellervee, Aleksandr; Kuznetsov, Anatoli; Laisaar, Arlentin; Trinkunas, Gediminas; Freiberg, Arvi

2003-01-01

The absorption and emission spectra of excitons in LH2 antenna complexes from the photosynthetic purple bacterium Rhodobacter sphaeroides have been studied under hydrostatic pressure. The measurements made between ambient pressure and 6 kbar over a broad temperature range reveal largely different rates of the pressure-induced shifts for the absorption and emission bands. Numerical calculations based on exciton polaron model provide evidence for the exciton self-trapping at ambient pressure as well as for the pressure stabilization of the self-trapped exciton states responsible for the emission, whereas the light absorbing states belong to nearly free excitons over the whole pressure and temperature ranges studied

A mixed incoherent feed-forward loop contributes to the regulation of bacterial photosynthesis genes.

Science.gov (United States)

Mank, Nils N; Berghoff, Bork A; Klug, Gabriele

2013-03-01

Living cells use a variety of regulatory network motifs for accurate gene expression in response to changes in their environment or during differentiation processes. In Rhodobacter sphaeroides, a complex regulatory network controls expression of photosynthesis genes to guarantee optimal energy supply on one hand and to avoid photooxidative stress on the other hand. Recently, we identified a mixed incoherent feed-forward loop comprising the transcription factor PrrA, the sRNA PcrZ and photosynthesis target genes as part of this regulatory network. This point-of-view provides a comparison to other described feed-forward loops and discusses the physiological relevance of PcrZ in more detail.

Filtering reducer of flushing fluid

Energy Technology Data Exchange (ETDEWEB)

Secu, P; Apostu, M; Basarabescu, T; Popescu, F

1981-02-28

This is a patent of a filtering reducer of flushing fluid on a water base with low content of solid particles used at temperatures of roughly 200/sup 0/C. With the use of the proposed filtering reducer, there is no excessive increase in viscosity and gelatinization of the flushing fluids without restriction in the quantity of reducer needed to guarantee the required filtering. There is a possibility of recovering the polyalkylphenol vat residues obtained in the production of nonyl phenol. It is possible to reduce the time of treatment and dissolving of the product; there is no danger of plugging of the productive oil beds. The process of hydration of clay is excluded.

Process for reducing the pertechnetate anion

International Nuclear Information System (INIS)

Ruddock, C.F.

1980-01-01

Process for reducing the 'pertechnetate' ion TcO 4 - , whereby an aqueous solution of 'pertechnetate' is mixed with tin metal or a tin alloy as 'pertechnetate' reducing agent, and a soluble salt of a metal below tin in the electro-chemical tension scale, as activator for the reducing tin. This reduced 'pertechnetate' is used for forming usable complexes in medical diagnosis exploration [fr

[Improving Agricultural Safety of Soils Contaminated with Polycyclic Aromatic Hydrocarbons by In Situ Bioremediation].

Science.gov (United States)

Jiao, Hai-huan; Pan, Jian-gang; Xu, Shena-jun; Bai, Zhi-hui; Wang, Dong; Huang, Zhan-bin

2015-08-01

In order to reduce the risk of enrichment of polycyclic aromatic hydrocarbons (PAHs) in crops, reduce the potential hazards of food-sourced PAHs to human and increase the agricultural safety of PAHs contaminated soils, the bio-augmented removal of polycyclic aromatic hydrocarbons (PAHs) was investigated through in situ remediation by introducing Rhodobacter sphaeroides (RS) into the agricultural soil contaminated by PAHs. The 50-times diluted RS was sprayed on leaf surface (in area B) or irrigated to roots (in area D). The treatment of spraying water of the equal amount was taken as the control (A) and the wheat field without any treatment as the blank (CK). Treatments were conducted since wheat seeding. Soil and wheat samples were collected in the mature period to analyze the changes of community structure of the soil microorganisms and the concentration of PAHs in soils and investigate the strengthening and restoration effects of RS on PAHs contaminated soils. Compared to the CK Area, the areas B and D revealed that the variation ratio of phospholipid fatty acids (PLFAs) that were the biomarker of soil microorganisms was 29.6%, and the ratio of total PAHs removed was increased 1.59 times and 1.68 times, respectively. The dry weight of wheat grain of 50 spikes was increased by 8.95% and 12.5%, respectively, and the enrichment factor of total PAHs was decreased by 58.9% and 62.2% respectively in the wheat grains. All the results suggested that RS reduced enrichment of PAHs in wheat grains and increased wheat yield, which had great exploitation and utilization potentiality in repairing and improving the agricultural safety of the soils contaminated with PHAs.

Bactericide for sulfate-reducing bacteria

Energy Technology Data Exchange (ETDEWEB)

Shklyar, T F; Anoshina, G M; Blokhin, V Ye; Kisarrev, Ye L; Novikovsa, G M

1981-01-01

The aim of the invention is to find a bactericide for sulfate-reducing bacteria of oil fields in Western Siberia in order to suppress the biocorrosive activity on oil industry equipment. This goal is achieved by using M-nitroacetanylide as the bactericide of sulfate-reducing bacteria. This agent suppresses the activity of a stored culture of sulfate-reducing bacteria that comes from industrial waste waters injection wells of the Smotlor oil field.

Using REDUCE in high energy physics

International Nuclear Information System (INIS)

Grozin, A.G.

1997-01-01

This book describes the use of the symbolic manipulation language REDUCE in particle physics. There are several general purpose mathematics packages available to physicists, including Mathematica, Maple, and REDUCE. Each has advantages and disadvantages, but REDUCE has been found to be both powerful and convenient in solving a wide range of problems. This book introduces the reader to REDUCE and demonstrates its utility as a mathematical tool in physics. The first chapter of the book describes the REDUCE system, including some library packages. The following chapters show the use of REDUCE in examples from classical mechanics, hydrodynamics, general relativity, and quantum mechanics. The rest of the book systematically presents the Standard Model of particle physics (QED, weak interactions, QCD). A large number of scattering and decay processes are calculated with REDUCE. All example programs from the book can be downloaded via Internet. The emphasis throughout is on learning through worked examples. This will be an essential introduction and reference for high energy and theoretical physicists. (author)

Metabolic engineering in chemolithoautotrophic hosts for the production of fuels and chemicals.

Science.gov (United States)

Nybo, S Eric; Khan, Nymul E; Woolston, Benjamin M; Curtis, Wayne R

2015-07-01

The ability of autotrophic organisms to fix CO2 presents an opportunity to utilize this 'greenhouse gas' as an inexpensive substrate for biochemical production. Unlike conventional heterotrophic microorganisms that consume carbohydrates and amino acids, prokaryotic chemolithoautotrophs have evolved the capacity to utilize reduced chemical compounds to fix CO2 and drive metabolic processes. The use of chemolithoautotrophic hosts as production platforms has been renewed by the prospect of metabolically engineered commodity chemicals and fuels. Efforts such as the ARPA-E electrofuels program highlight both the potential and obstacles that chemolithoautotrophic biosynthetic platforms provide. This review surveys the numerous advances that have been made in chemolithoautotrophic metabolic engineering with a focus on hydrogen oxidizing bacteria such as the model chemolithoautotrophic organism (Ralstonia), the purple photosynthetic bacteria (Rhodobacter), and anaerobic acetogens. Two alternative strategies of microbial chassis development are considered: (1) introducing or enhancing autotrophic capabilities (carbon fixation, hydrogen utilization) in model heterotrophic organisms, or (2) improving tools for pathway engineering (transformation methods, promoters, vectors etc.) in native autotrophic organisms. Unique characteristics of autotrophic growth as they relate to bioreactor design and process development are also discussed in the context of challenges and opportunities for genetic manipulation of organisms as production platforms. Copyright © 2015 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.

Reducing elevator energy use: A comparison of posted feedback and reduced elevator convenience

Science.gov (United States)

Houten, Ron Van; Nau, Paul A.; Merrigan, Michael

1981-01-01

The effects of two different procedures for reducing elevator energy use were assessed using a multiple-baseline design. In the first procedure, feedback about the amount of energy consumed by the elevators each week was posted on each elevator door. Later, signs advocating the use of stairs to save energy and improve health were posted next to the feedback signs. In the second procedure, the time required to travel between floors was increased by adding a delay to the elevator door closing mechanisms. Results indicated that neither feedback alone nor feedback plus educational signs reduced the amount of energy consumed by the elevators. However, use of the door delay reduced consumption by one-third in all elevators. A second experiment replicated the effect of the door delay on energy consumption and, in addition, demonstrated that the door delay also produced a reduction in the number of persons using the elevator. The second experiment also showed that, following an initial period during which a full delay was in effect, a gradual reduction of the delay interval resulted in continued energy conservation. Reduced convenience as a general strategy for energy conservation is discussed. PMID:16795648

Reducing The Nuclear Danger

Science.gov (United States)

1995-10-01

off convention • Eliminate the civil use of HEU (includes RERTR ) • Reduce stockpiles of civil HEU and plutonium • Promote alternatives to the...these countries. ANL supports the Department’s Reduced Enrichment for Research and Test Reactor ( RERTR ) Program by providing the technical means to...scientists and engineers at 60 institutes in Russia, Ukraine, Kazakhstan and Belarus. The United States and Russia have agreed to pursue a joint RERTR

Servo Reduces Friction In Flexure Bearing

Science.gov (United States)

Clingman, W. Dean

1991-01-01

Proposed servocontrol device reduces such resistive torques as stiction, friction, ripple, and cogging in flexure bearing described in LAR-14348, "Flexure Bearing Reduces Startup Friction". Reduces frictional "bump" torque encountered when bearing ball runs into buildup of grease on bearing race. Also used as cable follower to reduce torque caused by cable and hoses when they bend because of motion of bearing. New device includes torquer across ball race. Torquer controlled by servo striving to keep flexure at null, removing torque to outer ring. In effect, device is inner control loop reducing friction, but does not control platforms or any outer-control-loop functions.

Holonomy-reduced dynamics of triatomic molecules

International Nuclear Information System (INIS)

Ciftci, Uenver; Waalkens, Holger

2011-01-01

Whereas it is easy to reduce the translational symmetry of a molecular system using, e.g., Jacobi coordinates, the situation is much more involved for rotational symmetry. In this paper, we address the latter problem using holonomy reduction. We suggest that the configuration space may be considered as the reduced holonomy bundle with a connection induced by the mechanical connection. Using the fact that for the special case of the three-body problem the holonomy group is SO(2) (as opposed to SO(3) like in systems with more than three bodies), we obtain a holonomy-reduced configuration space of topology R + 3 xS 1 . The dynamics then takes place on the cotangent bundle over the holonomy-reduced configuration space. On this phase space, there is an S 1 symmetry action coming from the conserved reduced angular momentum which can be reduced using the standard symplectic reduction method. Using a theorem by Arnold it follows that the resulting symmetry-reduced phase space is again a natural mechanical phase space, i.e. a cotangent bundle. This is different from what is obtained from the usual approach where symplectic reduction is used from the outset. This difference is discussed in some detail, and a connection between the reduced dynamics of a triatomic molecule and the motion of a charged particle in a magnetic field is established.

Holonomy-reduced dynamics of triatomic molecules

Energy Technology Data Exchange (ETDEWEB)

Ciftci, Uenver [Department of Mathematics, Namik Kemal University, 59030 Tekirdag (Turkey); Waalkens, Holger, E-mail: uciftci@nku.edu.tr, E-mail: h.waalkens@rug.nl [Johann Bernoulli Institute for Mathematics and Computer Science, University of Groningen, PO Box 407, 9700 AK Groningen (Netherlands)

2011-04-22

Whereas it is easy to reduce the translational symmetry of a molecular system using, e.g., Jacobi coordinates, the situation is much more involved for rotational symmetry. In this paper, we address the latter problem using holonomy reduction. We suggest that the configuration space may be considered as the reduced holonomy bundle with a connection induced by the mechanical connection. Using the fact that for the special case of the three-body problem the holonomy group is SO(2) (as opposed to SO(3) like in systems with more than three bodies), we obtain a holonomy-reduced configuration space of topology R{sub +}{sup 3}xS{sup 1}. The dynamics then takes place on the cotangent bundle over the holonomy-reduced configuration space. On this phase space, there is an S{sup 1} symmetry action coming from the conserved reduced angular momentum which can be reduced using the standard symplectic reduction method. Using a theorem by Arnold it follows that the resulting symmetry-reduced phase space is again a natural mechanical phase space, i.e. a cotangent bundle. This is different from what is obtained from the usual approach where symplectic reduction is used from the outset. This difference is discussed in some detail, and a connection between the reduced dynamics of a triatomic molecule and the motion of a charged particle in a magnetic field is established.

Using reduce in supersymmetry

International Nuclear Information System (INIS)

Santos, R.P. dos.

1987-01-01

A procedure which allows one to do Supersymmetry calculus in REDUCE is described. Using the concept of an eight-dimensional 'superspace' (spanned by four space-time and four anticommuting coordinates) and of 'superfields' (which represent an entire supermultiplet of particles that transform among themselves), covariant derivatives with respect to supersymmetry are defined. Then, combining the vector facility and LET statement in REDUCE, spinors are simulated in a way to control the algebraic manipulation. (G.D.F.) [pt

Method and container for reducing pertechnetate

International Nuclear Information System (INIS)

Ruddock, C.F.

1980-01-01

A method of reducing the pertechnetate in TcO 4 - comprises mixing together an aqueous solution of pertechnetate, e.g. the eluant from a technetium generator, metallic tin or an alloy thereof as a reducing agent for the pertechnetate, and a soluble salt of a metal below tin in the electrochemical series, e.g. copper, as an activator for the tin metal reducing agent. A complexing agent for the reduced technetium or a colloid stabiliser may also be included. The pH is preferably 3 to 12. Also claimed is a closed container containing the tin reducing agent, the activator, and the complexant or colloid stabiliser if used, preferably in a freeze-dried sterile state, to which the pertechnetate solution may be added. (author)

Reducing Employment Insecurity

Directory of Open Access Journals (Sweden)

Florence Lebert

2016-10-01

Full Text Available The perception of job insecurity is known to be a stressful condition for employees. Less is known about employment insecurity and the ways employees and their families deal with it. This study investigates whether participation in further training is a strategy that employees adopt to reduce perceived employment insecurity. As participation in further training is often costly and time-consuming, we assume that the family context is of importance for the decision to take part in further training. To take account of possible self-selection, we apply a propensity score matching procedure on longitudinal data from the Swiss Household Panel (2004-2013. Three main findings can be emphasized: first, participation in further training is not a strategy adopted particularly by employees who perceive high employment insecurity as they are less likely to train than their secure counterparts. Second, even though further training is not a strategy that is actively adopted, employees who train subsequently report lower levels of perceived employment insecurity. Third, the family context indeed influences the likelihood to train: partnered employees are more likely to train and preschool-aged children act as a constraint on women’s but enhance men’s participation in further training. Yet, in the context of high perceived employment insecurity, children generally reduce their parents’ likelihood to train as the parents may turn to other strategies that reduce perceived employment insecurity.

Reducing Pesticide Drift

Science.gov (United States)

Provides information about pesticide spray drift, including problems associated with drift, managing risks from drift and the voluntary Drift Reduction Technology program that seeks to reduce spray drift through improved spray equipment design.

Sleep can reduce proactive interference.

Science.gov (United States)

Abel, Magdalena; Bäuml, Karl-Heinz T

2014-01-01

Sleep has repeatedly been connected to processes of memory consolidation. While extensive research indeed documents beneficial effects of sleep on memory, little is yet known about the role of sleep for interference effects in episodic memory. Although two prior studies reported sleep to reduce retroactive interference, no sleep effect has previously been found for proactive interference. Here we applied a study format differing from that employed by the prior studies to induce a high degree of proactive interference, and asked participants to encode a single list or two interfering lists of paired associates via pure study cycles. Testing occurred after 12 hours of diurnal wakefulness or nocturnal sleep. Consistent with the prior work, we found sleep in comparison to wake did not affect memory for the single list, but reduced retroactive interference. In addition we found sleep reduced proactive interference, and reduced retroactive and proactive interference to the same extent. The finding is consistent with the view that arising benefits of sleep are caused by the reactivation of memory contents during sleep, which has been suggested to strengthen and stabilise memories. Such stabilisation may make memories less susceptible to competition from interfering memories at test and thus reduce interference effects.

Reduced turning frequency and delayed poultry manure addition reduces N loss from sugarcane compost.

Science.gov (United States)

Bryndum, S; Muschler, R; Nigussie, A; Magid, J; de Neergaard, A

2017-07-01

Composting is an effective method to recycle biodegradable waste as soil amendment in smallholder farming systems. Although all essential plant nutrients are found in compost, a substantial amount of nitrogen is lost during composting. This study therefore investigated the potential of reducing N losses by (i) delaying the addition of nitrogen-rich substrates (i.e. poultry manure), and (ii) reducing the turning frequency during composting. Furthermore, we tested the effect of compost application method on nitrogen mineralization. Sugarcane-waste was composted for 54days with addition of poultry manure at the beginning (i.e. early addition) or after 21days of composting (delayed addition). The compost pile was then turned either every three or nine days. Composts were subsequently applied to soil as (i) homogeneously mixed, or (ii) stratified, and incubated for 28days to test the effect of compost application on nitrogen mineralization. The results showed that delayed addition of poultry manure reduced total nitrogen loss by 33% and increased mineral nitrogen content by >200% compared with early addition. Similarly, less frequent turning reduced total N loss by 12% compared with frequent turning. Stratified placement of compost did not enhance N mineralization compared to a homogeneous mixing. Our results suggested that simple modifications of the composting process (i.e. delayed addition and/or turning frequency) could significantly reduce N losses and improve the plant-nutritional value of compost. Copyright © 2017 Elsevier Ltd. All rights reserved.

Production of bioplastics and hydrogen gas by photosynthetic microorganisms

Science.gov (United States)

Yasuo, Asada; Masato, Miyake; Jun, Miyake

1998-03-01

Our efforts have been aimed at the technological basis of photosynthetic-microbial production of materials and an energy carrier. We report here accumulation of poly-(3-hydroxybutyrate) (PHB), a raw material of biodegradable plastics and for production of hydrogen gas, and a renewable energy carrier by photosynthetic microorganisms (tentatively defined as cyanobacteria plus photosynthetic bateria, in this report). A thermophilic cyanobacterium, Synechococcus sp. MA19 that accumulates PHB at more than 20% of cell dry wt under nitrogen-starved conditions was isolated and microbiologically identified. The mechanism of PHB accumulation was studied. A mesophilic Synechococcus PCC7942 was transformed with the genes encoding PHB-synthesizing enzymes from Alcaligenes eutrophus. The transformant accumulated PHB under nitrogen-starved conditions. The optimal conditions for PHB accumulation by a photosynthetic bacterium grown on acetate were studied. Hydrogen production by photosynthetic microorganisms was studied. Cyanobacteria can produce hydrogen gas by nitrogenase or hydrogenase. Hydrogen production mediated by native hydrogenase in cyanobacteria was revealed to be in the dark anaerobic degradation of intracellular glycogen. A new system for light-dependent hydrogen production was targeted. In vitro and in vivo coupling of cyanobacterial ferredoxin with a heterologous hydrogenase was shown to produce hydrogen under light conditions. A trial for genetic trasformation of Synechococcus PCC7942 with the hydrogenase gene from Clostridium pasteurianum is going on. The strong hydrogen producers among photosynthetic bacteria were isolated and characterized. Co-culture of Rhodobacter and Clostriumdium was applied to produce hydrogen from glucose. Conversely in the case of cyanobacteria, genetic regulation of photosynthetic proteins was intended to improve conversion efficiency in hydrogen production by the photosynthetic bacterium, Rhodobacter sphaeroides RV. A mutant acquired by

Reduced Numerical Approximation of Reduced Fluid-Structure Interaction Problems With Applications in Hemodynamics

Directory of Open Access Journals (Sweden)

Claudia M. Colciago

2018-06-01

Full Text Available This paper deals with fast simulations of the hemodynamics in large arteries by considering a reduced model of the associated fluid-structure interaction problem, which in turn allows an additional reduction in terms of the numerical discretisation. The resulting method is both accurate and computationally cheap. This goal is achieved by means of two levels of reduction: first, we describe the model equations with a reduced mathematical formulation which allows to write the fluid-structure interaction problem as a Navier-Stokes system with non-standard boundary conditions; second, we employ numerical reduction techniques to further and drastically lower the computational costs. The non standard boundary condition is of a generalized Robin type, with a boundary mass and boundary stiffness terms accounting for the arterial wall compliance. The numerical reduction is obtained coupling two well-known techniques: the proper orthogonal decomposition and the reduced basis method, in particular the greedy algorithm. We start by reducing the numerical dimension of the problem at hand with a proper orthogonal decomposition and we measure the system energy with specific norms; this allows to take into account the different orders of magnitude of the state variables, the velocity and the pressure. Then, we introduce a strategy based on a greedy procedure which aims at enriching the reduced discretization space with low offline computational costs. As application, we consider a realistic hemodynamics problem with a perturbation in the boundary conditions and we show the good performances of the reduction techniques presented in the paper. The results obtained with the numerical reduction algorithm are compared with the one obtained by a standard finite element method. The gains obtained in term of CPU time are of three orders of magnitude.

Reducing Childhood Obesity

Science.gov (United States)

... Bar Home Current Issue Past Issues Reducing Childhood Obesity Past Issues / Summer 2007 Table of Contents For ... Ga. were the first three We Can! cities. Obesity Research: A New Approach The percentage of children ...

System for actively reducing sound

NARCIS (Netherlands)

Berkhoff, Arthur P.

2005-01-01

A system for actively reducing sound from a primary noise source, such as traffic noise, comprising: a loudspeaker connector for connecting to at least one loudspeaker for generating anti-sound for reducing said noisy sound; a microphone connector for connecting to at least a first microphone placed

Why reduce health inequalities?

Science.gov (United States)

Woodward, A; Kawachi, I

2000-12-01

It is well known that social, cultural and economic factors cause substantial inequalities in health. Should we strive to achieve a more even share of good health, beyond improving the average health status of the population? We examine four arguments for the reduction of health inequalities.1 Inequalities are unfair. Inequalities in health are undesirable to the extent that they are unfair, or unjust. Distinguishing between health inequalities and health inequities can be contentious. Our view is that inequalities become "unfair" when poor health is itself the consequence of an unjust distribution of the underlying social determinants of health (for example, unequal opportunities in education or employment).2 Inequalities affect everyone. Conditions that lead to marked health disparities are detrimental to all members of society. Some types of health inequalities have obvious spillover effects on the rest of society, for example, the spread of infectious diseases, the consequences of alcohol and drug misuse, or the occurrence of violence and crime.3 Inequalities are avoidable. Disparities in health are avoidable to the extent that they stem from identifiable policy options exercised by governments, such as tax policy, regulation of business and labour, welfare benefits and health care funding. It follows that health inequalities are, in principle, amenable to policy interventions. A government that cares about improving the health of the population ought therefore to incorporate considerations of the health impact of alternative options in its policy setting process.3 Interventions to reduce health inequalities are cost effective. Public health programmes that reduce health inequalities can also be cost effective. The case can be made to give priority to such programmes (for example, improving access to cervical cancer screening in low income women) on efficiency grounds. On the other hand, few programmes designed to reduce health inequalities have been formally

Reconstruction and Quality Control of a Genome-Scale Metabolic Model for Methylococcus capsulatus

DEFF Research Database (Denmark)

Lieven, Christian

Climate-change induced food scarcity is a grim prospect for the future of humanity. Alas, increasingly detrimental effects of global warming and overpopulation are predicted to beget this outlook by the year 2050. Fortunately, the production of single-cell protein (SCP) from microbial fermentations...

40 CFR 141.623 - Reduced monitoring.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 22 2010-07-01 2010-07-01 false Reduced monitoring. 141.623 Section....623 Reduced monitoring. (a) You may reduce monitoring to the level specified in the table in this paragraph (a) any time the LRAA is ≤0.040 mg/L for TTHM and ≤0.030 mg/L for HAA5 at all monitoring locations...

A disordered polaron model for polarized fluorescence excitation spectra of LH1 and LH2 bacteriochlorophyll antenna aggregates

International Nuclear Information System (INIS)

Trinkunas, Gediminas; Freiberg, Arvi

2006-01-01

Excitonic polarons in antenna complexes are subject to static lattice disorder. A model has been developed to analyze polarized fluorescence excitation spectra of circular light-harvesting complexes from purple photosynthetic bacteria containing bacteriochlorophyll as the main photoactive pigment that includes both diagonal (energetic) and off-diagonal (structural) disorders. Essential differences of disorder realizations seem to exist between the core LH1 and peripheral LH2 complexes from the bacterium Rhodobacter sphaeroides. The disorder in LH1 appears to be dominated by the structural disorder, while that in LH2, by energetic one. These differences may be due to relatively bigger size of the LH1 complex and, consequently, with its enhanced structural flexibility

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.

Implementing Parallel Google Map-Reduce in Eden

DEFF Research Database (Denmark)

Berthold, Jost; Dieterle, Mischa; Loogen, Rita

2009-01-01

Recent publications have emphasised map-reduce as a general programming model (labelled Google map-reduce), and described existing high-performance implementations for large data sets. We present two parallel implementations for this Google map-reduce skeleton, one following earlier work, and one...... of the Google map-reduce skeleton in usage and performance, and deliver runtime analyses for example applications. Although very flexible, the Google map-reduce skeleton is often too general, and typical examples reveal a better runtime behaviour using alternative skeletons....

Reduced waste generation technical work plan

International Nuclear Information System (INIS)

1987-05-01

The United States Department of Energy has established policies for avoiding plutonium losses to the waste streams and minimizing the generation of wastes produced at its nuclear facilities. This policy is evidenced in DOE Order 5820.2, which states ''Technical and administrative controls shall be directed towards reducing the gross volume of TRU waste generated and the amount of radioactivity in such waste.'' To comply with the DOE directive, the Defense Transuranic Waste Program (DTWP) supports and provides funding for specific research and development tasks at the various DOE sites to reduce the generation of waste. This document has been prepared to give an overview of current and past Reduced Waste Generation task activities which are to be based on technical and cost/benefit factors. The document is updated annually, or as needed, to reflect the status of program direction. Reduced Waste Generation (RWG) tasks encompass a wide range of goals which are basically oriented toward (1) avoiding the generation of waste, (2) changing processes or operations to reduce waste, (3) converting TRU waste into LLW by sorting or decontamination, and (4) reducing volumes through operations such as incineration or compaction

Microprocessor Protection of Power Reducing Transformers

OpenAIRE

F. A. Romanuk; S. P. Korolev; M. S. Loman

2011-01-01

The paper contains analysis of advantages and disadvantages of existing differential protection terminals of power reducing transformers. The paper shows that there are good reasons to develop microprocessor protection of power reducing transformer which contains required functions and settings and which is based on Belarusian principles of relay protection system construction. The paper presents functional structure of microprocessor terminal of power reducing transformer which is developed. 

Reducing Lookups for Invariant Checking

DEFF Research Database (Denmark)

Thomsen, Jakob Grauenkjær; Clausen, Christian; Andersen, Kristoffer Just

2013-01-01

This paper helps reduce the cost of invariant checking in cases where access to data is expensive. Assume that a set of variables satisfy a given invariant and a request is received to update a subset of them. We reduce the set of variables to inspect, in order to verify that the invariant is still...

Microprocessor Protection of Power Reducing Transformers

Directory of Open Access Journals (Sweden)

F. A. Romanuk

2011-01-01

Full Text Available The paper contains analysis of advantages and disadvantages of existing differential protection terminals of power reducing transformers. The paper shows that there are good reasons to develop microprocessor protection of power reducing transformer which contains required functions and settings and which is based on Belarusian principles of relay protection system construction. The paper presents functional structure of microprocessor terminal of power reducing transformer which is developed. 

IHadoop: Asynchronous iterations for MapReduce

KAUST Repository

Elnikety, Eslam Mohamed Ibrahim

2011-11-01

MapReduce is a distributed programming frame-work designed to ease the development of scalable data-intensive applications for large clusters of commodity machines. Most machine learning and data mining applications involve iterative computations over large datasets, such as the Web hyperlink structures and social network graphs. Yet, the MapReduce model does not efficiently support this important class of applications. The architecture of MapReduce, most critically its dataflow techniques and task scheduling, is completely unaware of the nature of iterative applications; tasks are scheduled according to a policy that optimizes the execution for a single iteration which wastes bandwidth, I/O, and CPU cycles when compared with an optimal execution for a consecutive set of iterations. This work presents iHadoop, a modified MapReduce model, and an associated implementation, optimized for iterative computations. The iHadoop model schedules iterations asynchronously. It connects the output of one iteration to the next, allowing both to process their data concurrently. iHadoop\\'s task scheduler exploits inter-iteration data locality by scheduling tasks that exhibit a producer/consumer relation on the same physical machine allowing a fast local data transfer. For those iterative applications that require satisfying certain criteria before termination, iHadoop runs the check concurrently during the execution of the subsequent iteration to further reduce the application\\'s latency. This paper also describes our implementation of the iHadoop model, and evaluates its performance against Hadoop, the widely used open source implementation of MapReduce. Experiments using different data analysis applications over real-world and synthetic datasets show that iHadoop performs better than Hadoop for iterative algorithms, reducing execution time of iterative applications by 25% on average. Furthermore, integrating iHadoop with HaLoop, a variant Hadoop implementation that caches

IHadoop: Asynchronous iterations for MapReduce

KAUST Repository

Elnikety, Eslam Mohamed Ibrahim; El Sayed, Tamer S.; Ramadan, Hany E.

2011-01-01

MapReduce is a distributed programming frame-work designed to ease the development of scalable data-intensive applications for large clusters of commodity machines. Most machine learning and data mining applications involve iterative computations over large datasets, such as the Web hyperlink structures and social network graphs. Yet, the MapReduce model does not efficiently support this important class of applications. The architecture of MapReduce, most critically its dataflow techniques and task scheduling, is completely unaware of the nature of iterative applications; tasks are scheduled according to a policy that optimizes the execution for a single iteration which wastes bandwidth, I/O, and CPU cycles when compared with an optimal execution for a consecutive set of iterations. This work presents iHadoop, a modified MapReduce model, and an associated implementation, optimized for iterative computations. The iHadoop model schedules iterations asynchronously. It connects the output of one iteration to the next, allowing both to process their data concurrently. iHadoop's task scheduler exploits inter-iteration data locality by scheduling tasks that exhibit a producer/consumer relation on the same physical machine allowing a fast local data transfer. For those iterative applications that require satisfying certain criteria before termination, iHadoop runs the check concurrently during the execution of the subsequent iteration to further reduce the application's latency. This paper also describes our implementation of the iHadoop model, and evaluates its performance against Hadoop, the widely used open source implementation of MapReduce. Experiments using different data analysis applications over real-world and synthetic datasets show that iHadoop performs better than Hadoop for iterative algorithms, reducing execution time of iterative applications by 25% on average. Furthermore, integrating iHadoop with HaLoop, a variant Hadoop implementation that caches

Syntheses of 18F-labeled reduced haloperidol and 11C-labeled reduced 3-N-methylspiperone

International Nuclear Information System (INIS)

Ravert, H.T.; Dannals, R.F.; Wilson, A.A.; Wong, D.F.; Wagner, H.N. Jr.

1991-01-01

18 F-Labeled reduced haloperidol and 11 C-labeled reduced 3-N-methylspiperone were synthesized in a convenient and quantitative one step reduction from 18 F-labeled haloperidol and 11 C-labeled N-methylspiperone, respectively. Both products were purified by semipreparative HPLC and were obtained at high specific activity and radiochemical purity. (author)

Tank closure reducing grout

International Nuclear Information System (INIS)

Caldwell, T.B.

1997-01-01

A reducing grout has been developed for closing high level waste tanks at the Savannah River Site in Aiken, South Carolina. The grout has a low redox potential, which minimizes the mobility of Sr 90 , the radionuclide with the highest dose potential after closure. The grout also has a high pH which reduces the solubility of the plutonium isotopes. The grout has a high compressive strength and low permeability, which enhances its ability to limit the migration of contaminants after closure. The grout was designed and tested by Construction Technology Laboratories, Inc. Placement methods were developed by the Savannah River Site personnel

5 CFR 831.631 - Post-retirement election of fully reduced annuity or partially reduced annuity to provide a...

Science.gov (United States)

2010-01-01

... annuity or partially reduced annuity to provide a current spouse annuity. 831.631 Section 831.631...) RETIREMENT Survivor Annuities Post-Retirement Elections § 831.631 Post-retirement election of fully reduced annuity or partially reduced annuity to provide a current spouse annuity. (a) Except as provided in...

5 CFR 831.632 - Post-retirement election of fully reduced annuity or partially reduced annuity to provide a...

Science.gov (United States)

2010-01-01

... annuity or partially reduced annuity to provide a former spouse annuity. 831.632 Section 831.632...) RETIREMENT Survivor Annuities Post-Retirement Elections § 831.632 Post-retirement election of fully reduced annuity or partially reduced annuity to provide a former spouse annuity. (a)(1) Except as provided in...

Reduced Braginskii equations

International Nuclear Information System (INIS)

Yagi, M.; Horton, W.

1994-01-01

A set of reduced Braginskii equations is derived without assuming flute ordering and the Boussinesq approximation. These model equations conserve the physical energy. It is crucial at finite β that the perpendicular component of Ohm's law be solved to ensure ∇·j=0 for energy conservation

Reducing rotor weight

Energy Technology Data Exchange (ETDEWEB)

Cheney, M.C. [PS Enterprises, Inc., Glastonbury, CT (United States)

1997-12-31

The cost of energy for renewables has gained greater significance in recent years due to the drop in price in some competing energy sources, particularly natural gas. In pursuit of lower manufacturing costs for wind turbine systems, work was conducted to explore an innovative rotor designed to reduce weight and cost over conventional rotor systems. Trade-off studies were conducted to measure the influence of number of blades, stiffness, and manufacturing method on COE. The study showed that increasing number of blades at constant solidity significantly reduced rotor weight and that manufacturing the blades using pultrusion technology produced the lowest cost per pound. Under contracts with the National Renewable Energy Laboratory and the California Energy Commission, a 400 kW (33m diameter) turbine was designed employing this technology. The project included tests of an 80 kW (15.5m diameter) dynamically scaled rotor which demonstrated the viability of the design.

Early Bacteriopheophytin Reduction in Charge Separation in Reaction Centers of Rhodobacter sphaeroides

NARCIS (Netherlands)

Zhu, J.; van Stokkum, I.H.M.; Paparelli, L.; Jones, M.R.; Groot, M.L.

2013-01-01

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

Design meeting on reduced technical objectives/reduced cost ITER options

International Nuclear Information System (INIS)

Spears, W.

1999-01-01

At this meeting, which took place at Garching, Germany in January 1999, means of reducing the overall cost for ITER to 50% where discussed. It was felt that a smaller plasma of high elongation and high triangularity was a step in the right direction. Further steps would include cheaper magnetic field coils, cheaper in-vessel components and also costly buildings

Reduced Braginskii equations

International Nuclear Information System (INIS)

Yagi, M.; Horton, W.

1993-11-01

A set of reduced Braginskii equations is derived without assuming flute ordering and the Boussinesq approximation. These model equations conserve the physical energy. It is crucial at finite β that we solve the perpendicular component of Ohm's law to conserve the physical energy while ensuring the relation ∇ · j = 0

Reuse, Reduce, Recycle.

Science.gov (United States)

Briscoe, Georgia

1991-01-01

Discussion of recycling paper in law libraries is also applicable to other types of libraries. Results of surveys of law libraries that investigated recycling practices in 1987 and again in 1990 are reported, and suggestions for reducing the amount of paper used and reusing as much as possible are offered. (LRW)

Reducing Sugar in Children's Diets: Why? How?

Science.gov (United States)

Rogers, Cosby S.; Morris, Sandra S.

1986-01-01

Maintains that sugar intake should be reduced in young children's diets because of its link to dental cavities, poor nutrition, and obesity. Reducing the focus on sweetness, limiting sugar consumption, and using natural sources of sweetness and other treats are ways to help reduce sugar intake. (BB)

Reduced chemical kinetic mechanisms for hydrocarbon fuels

International Nuclear Information System (INIS)

Montgomery, C.J.; Cremer, M.A.; Heap, M.P.; Chen, J-Y.; Westbrook, C.K.; Maurice, L.Q.

1999-01-01

Using CARM (Computer Aided Reduction Method), a computer program that automates the mechanism reduction process, a variety of different reduced chemical kinetic mechanisms for ethylene and n-heptane have been generated. The reduced mechanisms have been compared to detailed chemistry calculations in simple homogeneous reactors and experiments. Reduced mechanisms for combustion of ethylene having as few as 10 species were found to give reasonable agreement with detailed chemistry over a range of stoichiometries and showed significant improvement over currently used global mechanisms. The performance of reduced mechanisms derived from a large detailed mechanism for n-heptane was compared to results from a reduced mechanism derived from a smaller semi-empirical mechanism. The semi-empirical mechanism was advantageous as a starting point for reduction for ignition delay, but not for PSR calculations. Reduced mechanisms with as few as 12 species gave excellent results for n-heptane/air PSR calculations but 16-25 or more species are needed to simulate n-heptane ignition delay

Reduced Braginskii equations

Energy Technology Data Exchange (ETDEWEB)

Yagi, M. [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan). Naka Fusion Research Establishment; Horton, W. [Texas Univ., Austin, TX (United States). Inst. for Fusion Studies

1993-11-01

A set of reduced Braginskii equations is derived without assuming flute ordering and the Boussinesq approximation. These model equations conserve the physical energy. It is crucial at finite {beta} that we solve the perpendicular component of Ohm`s law to conserve the physical energy while ensuring the relation {del} {center_dot} j = 0.

Programming MapReduce with Scalding

CERN Document Server

Chalkiopoulos, Antonios

2014-01-01

This book is an easy-to-understand, practical guide to designing, testing, and implementing complex MapReduce applications in Scala using the Scalding framework. It is packed with examples featuring log-processing, ad-targeting, and machine learning. This book is for developers who are willing to discover how to effectively develop MapReduce applications. Prior knowledge of Hadoop or Scala is not required; however, investing some time on those topics would certainly be beneficial.

Interference, reduced action, and trajectories

OpenAIRE

Floyd, Edward R.

2006-01-01

Instead of investigating the interference between two stationary, rectilinear wave functions in a trajectory representation by examining the two rectilinear wave functions individually, we examine a dichromatic wave function that is synthesized from the two interfering wave functions. The physics of interference is contained in the reduced action for the dichromatic wave function. As this reduced action is a generator of the motion for the dichromatic wave function, it determines the dichroma...

Reduced Vlasov-Maxwell simulations

International Nuclear Information System (INIS)

Helluy, P.; Navoret, L.; Pham, N.; Crestetto, A.

2014-01-01

The Maxwell-Vlasov system is a fundamental model in physics. It can be applied to plasma simulations, charged particles beam, astrophysics, etc. The unknowns are the electromagnetic field, solution to the Maxwell equations and the distribution function, solution to the Vlasov equation. In this paper we review two different numerical methods for Vlasov-Maxwell simulations. The first method is based on a coupling between a Discontinuous Galerkin (DG) Maxwell solver and a Particle-In-Cell (PIC) Vlasov solver. The second method only uses a DG approach for the Vlasov and Maxwell equations. The Vlasov equation is first reduced to a space-only hyperbolic system thanks to the finite-element method. The two numerical methods are implemented using OpenCL in order to achieve high performance on recent Graphic Processing Units (GPU). We obtained interesting speedups, but we also observe that the PIC method is the most expensive part of the computation. Therefore we propose another fully Eulerian approach. Thanks to a decomposition of the distribution function on velocity basis functions, we obtain a reduced Vlasov model, which appears to be a hyperbolic system of conservation laws written only in the (x,t) space. We can thus adapt very easily our DG solver to the reduced model

Solid oxide fuel cells fueled with reducible oxides

Science.gov (United States)

Chuang, Steven S.; Fan, Liang Shih

2018-01-09

A direct-electrochemical-oxidation fuel cell for generating electrical energy includes a cathode provided with an electrochemical-reduction catalyst that promotes formation of oxygen ions from an oxygen-containing source at the cathode, a solid-state reduced metal, a solid-state anode provided with an electrochemical-oxidation catalyst that promotes direct electrochemical oxidation of the solid-state reduced metal in the presence of the oxygen ions to produce electrical energy, and an electrolyte disposed to transmit the oxygen ions from the cathode to the solid-state anode. A method of operating a solid oxide fuel cell includes providing a direct-electrochemical-oxidation fuel cell comprising a solid-state reduced metal, oxidizing the solid-state reduced metal in the presence of oxygen ions through direct-electrochemical-oxidation to obtain a solid-state reducible metal oxide, and reducing the solid-state reducible metal oxide to obtain the solid-state reduced metal.

Acid-reducing vagotomy is associated with reduced risk of subsequent ischemic heart disease in complicated peptic ulcer

Science.gov (United States)

Wu, Shih-Chi; Fang, Chu-Wen; Chen, William Tzu-Liang; Muo, Chih-Hsin

2016-01-01

Abstract Persistent exacerbation of a peptic ulcer may lead to a complicated peptic ulcer (perforation or/and bleeding). The management of complicated peptic ulcers has shifted from acid-reducing vagotomy, drainage, and gastrectomy to simple local suture or non-operative (endoscopic/angiographic) hemostasis. We were interested in the long-term effects of this trend change. In this study, complicated peptic ulcer patients who received acid-reducing vagotomy were compared with those who received simple suture/hemostasis to determine the risk of ischemic heart disease (IHD). This retrospective cohort study analyzed 335,680 peptic ulcer patients recorded from 2000 to 2006 versus 335,680 age-, sex-, comorbidity-, and index-year matched comparisons. Patients with Helicobacter pylori (HP) infection were excluded. In order to identify the effect of vagus nerve severance, patients who received gastrectomy or antrectomy were also excluded. The incidence of IHD in both cohorts, and in the complicated peptic ulcer patients who received acid-reducing vagotomy versus those who received simple suture or hemostasis was evaluated. The overall incidence of IHD was higher in patients with peptic ulcer than those without peptic ulcer (17.00 vs 12.06 per 1000 person-years), with an adjusted hazard ratio (aHR) of 1.46 based on multivariable Cox proportional hazards regression analysis controlling for age, sex, Charlson's comorbidity index, and death (competing risk). While comparing peptic ulcer patients with acid-reducing vagotomy to those with simple suture/hemostasis or those without surgical treatment, the aHR (0.58) was the lowest in the acid-reducing vagotomy group. Patients with peptic ulcer have an elevated risk of IHD. However, complicated peptic ulcer patients who received acid-reducing vagotomy were associated with reduced risk of developing IHD. PMID:27977613

Solar Cels With Reduced Contact Areas

Science.gov (United States)

Daud, T.; Crotty, G. T.; Kachare, A. H.; Lewis, J. T.

1987-01-01

Efficiency of silicon solar cells increased about 20 percent using smaller metal-contact area on silicon at front and back of each cell. Reduction in contact area reduces surface recombination velocity under contact and thus reduces reverse saturation current and increases opencircuit voltage..

Reduced multiplication modules

Indian Academy of Sciences (India)

if M is a von Neumann regular module (VNM); i.e., every principal submodule of M is a summand submodule. Also if M is an injective R-module, then M is a VNM. Keywords. Multiplication module; reduced module; minimal prime submodule;. Zariski topology; extremally disconnected. 1. Introduction. In this paper all rings are ...

Obstetric outcomes in reduced and non-reduced twin pregnancies. A single hospital experience

Directory of Open Access Journals (Sweden)

UmmKulthoum E. AlShelaly

2015-09-01

Full Text Available Objectives: To compare pregnancy outcomes between high-order multiple pregnancies resulting from assisted reproductive technology (ART reduced to twins and non-reduced pregnancies, and to evaluate indications for using ART. Methods: This is a descriptive retrospective review of women with high-order multiple pregnancies reduced to twin carried out at the Department of Obstetrics & Gynecology, King Faisal Specialist Hospital & Research Center, Riyadh, Saudi Arabia between December 2010 and December 2013. The control group consisted of subjects with twin pregnancies who received their fertility treatment at the same hospital during the same period. Results: One hundred and twelve women were included in this study. Of women reaching fetal viability, significantly more women delivered before the thirtieth week in the study group (50% versus 12%, p<0.004. Miscarriage/delivery prior to fetal viability, chorioamnionitis, and preterm premature rupture of membranes were statistically higher in the study group. A total of 83% of the miscarriages in the study group were in women carrying 4 or more fetuses initially, and 50% of women in the study group were multiparous with no clear indication for fertility treatment. Conclusion: Although fetal reduction is a safe procedure, it is associated with complications. Primary prevention of high-order multiple pregnancy is recommended.

Reduced Pain Sensation and Reduced BOLD Signal in Parietofrontal Networks during Religious Prayer.

Science.gov (United States)

Elmholdt, Else-Marie; Skewes, Joshua; Dietz, Martin; Møller, Arne; Jensen, Martin S; Roepstorff, Andreas; Wiech, Katja; Jensen, Troels S

2017-01-01

Previous studies suggest that religious prayer can alter the experience of pain via expectation mechanisms. While brain processes related to other types of top-down modulation of pain have been studied extensively, no research has been conducted on the potential effects of active religious coping. Here, we aimed at investigating the neural mechanisms during pain modulation by prayer and their dependency on the opioidergic system. Twenty-eight devout Protestants performed religious prayer and a secular contrast prayer during painful electrical stimulation in two fMRI sessions. Naloxone or saline was administered prior to scanning. Results show that pain intensity was reduced by 11% and pain unpleasantness by 26% during religious prayer compared to secular prayer. Expectancy predicted large amounts (70-89%) of the variance in pain intensity. Neuroimaging results revealed reduced neural activity during religious prayer in a large parietofrontal network relative to the secular condition. Naloxone had no significant effect on ratings or neural activity. Our results thus indicate that, under these conditions, pain modulation by prayer is not opioid-dependent. Further studies should employ an optimized design to explore whether reduced engagement of the frontoparietal system could indicate that prayer may attenuate pain through a reduction in processing of pain stimulus saliency and prefrontal control rather than through known descending pain inhibitory systems.

Interface for Light-Driven Electron Transfer by Photosynthetic Complexes Across Block Copolymer Membranes.

Science.gov (United States)

Kuang, Liangju; Olson, Tien L; Lin, Su; Flores, Marco; Jiang, Yunjiang; Zheng, Wan; Williams, JoAnn C; Allen, James P; Liang, Hongjun

2014-03-06

Incorporation of membrane proteins into nanodevices to mediate recognition and transport in a collective and scalable fashion remains a challenging problem. We demonstrate how nanoscale photovoltaics could be designed using robust synthetic nanomembranes with incorporated photosynthetic reaction centers (RCs). Specifically, RCs from Rhodobacter sphaeroides are reconstituted spontaneously into rationally designed polybutadiene membranes to form hierarchically organized proteopolymer membrane arrays via a charge-interaction-directed reconstitution mechanism. Once incorporated, the RCs are fully active for prolonged periods based upon a variety of spectroscopic measurements, underscoring preservation of their 3D pigment configuration critical for light-driven charge transfer. This result provides a strategy to construct solar conversion devices using structurally versatile proteopolymer membranes with integrated RC functions to harvest broad regions of the solar spectrum.

Microbial treatment of aqueous wastes

International Nuclear Information System (INIS)

Kim, Kug Chan; Lee, Kang Suk; Chun, Ki Jung; Kim, Jin Kyu; Kim, Sang Bok; Kim, In Gyu; Park, Hyo Kook

1992-12-01

1) General binding efficiencies by immobilized cells decrease in the order U > Pb > Cu > Cd. The metal binding immobilized Rhodospirillum rubrum exceeded that found for Rhodobacter capsulata. 2) The binding efficiencies for U, Pb, Cu and Cd were greatest at pH 4.5, 5.0, 5.0 and 7.0 respectively. Immobilized cells showed an increased metal-binding capacity over a wide pH range as compared those free cells. 3) The binding efficiency decreased with increasing the initial metal concentrations. 4) Uranium can easily be stripped from the immobilized cells over several binding-stripping cycles and the adsorptive capacity of the immobilized cells appeared to increase after the first few cycles. It is therefore possible to use the immobilized cells repeatedly with regeneration. (Author)

Two-photon excitation spectroscopy of carotenoid-containing and carotenoid-depleted LH2 complexes from purple bacteria.

Science.gov (United States)

Stepanenko, Ilya; Kompanetz, Viktor; Makhneva, Zoya; Chekalin, Sergey; Moskalenko, Andrei; Razjivin, Andrei

2009-08-27

We applied two-photon fluorescence excitation spectroscopy to LH2 complex from purple bacteria Allochromatium minutissimum and Rhodobacter sphaeroides . Bacteriochlorophyll fluorescence was measured under two-photon excitation of the samples within the 1200-1500 nm region. Spectra were obtained for both carotenoid-containing and -depleted complexes of each bacterium to allow their direct comparison. The depletion of carotenoids did not alter the two-photon excitation spectra of either bacteria. The spectra featured a wide excitation band around 1350 nm (2x675 nm, 14,800 cm(-1)) which strongly resembled two-photon fluorescence excitation spectra of similar complexes published by other authors. We consider obtained experimental data to be evidence of direct two-photon excitation of bacteriochlorophyll excitonic states in this spectral region.

Filter apparatus for actively reducing noise

NARCIS (Netherlands)

Berkhoff, Arthur P.; Nijsse, G.

2010-01-01

A filter apparatus for reducing noise from a primary noise source, comprising a secondary source signal connector for generating secondary noise to reduce said primary noise and a sensor connector for connecting to a sensor for measuring said primary and secondary noise as an error signal. A first

REDUCE system in elementary particle physics

International Nuclear Information System (INIS)

Grozin, A.G.

1990-01-01

This preprint is the first part of the problem book on using REDUCE for calculations of cross sections and decay probabilities in elementary particle physics. It contains the review of the necessary formulae and examples of using REDUCE for calculations with vectors and Dirac matrices. 5 refs.; 11 figs

Flow Boiling Critical Heat Flux in Reduced Gravity

Science.gov (United States)

Mudawar, Issam; Zhang, Hui; Hasan, Mohammad M.

2004-01-01

This study provides systematic method for reducing power consumption in reduced gravity systems by adopting minimum velocity required to provide adequate CHF and preclude detrimental effects of reduced gravity . This study proves it is possible to use existing 1 ge flow boiling and CHF correlations and models to design reduced gravity systems provided minimum velocity criteria are met

The sensory quality of allergen-controlled, fat-reduced, salt-reduced pork-ostrich sausages during storage.

Science.gov (United States)

Guzek, Dominika; Głąbska, Dominika; Brodowska, Marta; Godziszewska, Jolanta; Górska-Horczyczak, Elżbieta; Pogorzelska, Ewelina; Wojtasik-Kalinowska, Iwona; Wierzbicka, Agnieszka

2017-12-01

New meat products tailored to consumer health should be characterised by reduced sodium, fat and cholesterol contents and other health-promoting benefits. However, the food sector's greatest challenge is allergen-free production. Consumers are not willing to compromise the sensory quality of meat products for health. The aim of the present study was to analyse the influence of the storage time on the physical properties and consumer acceptance of allergen-controlled, fat-reduced, salt-reduced pork-ostrich sausages. The study focused on pork-ostrich sausages produced in accordance with a new patented technology, which focused on eliminating cross-contamination on-line in the plant, eliminating cross-contamination after preparation, and eliminating spices with high allergy potential. The production was focused on reducing fat (by approximately 50%) and salt (by approximately 30%) levels. No changes in the texture parameters of the sausage were observed during storage time; however, some changes in colour were observed. There were no significant differences in sensory consumer acceptability of pork-ostrich sausage after 14 days of storage; thus, it may be stated that the instrumentally assessed differences in colour did not influence consumer acceptance. The applied fat and NaCl reduction in the pork-ostrich sausages contributed to high consumer ratings and was not correlated with saltiness acceptability. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Reduced Worktime: Tool to Fight Umemployment

Science.gov (United States)

Levitan, Sar A.; Belous, Richard S.

1978-01-01

Discusses the use of reduced worktime, including work sharing, as a strategy in combating unemployment. Covers the experiences of Western European countries in using this strategy to reduce unemployment. It also covers the negative aspects of work sharing, Americans' desires for increased leisure time, and, finally, some issues and answers. (EM)

Six ways to reduce inventory.

Science.gov (United States)

Lunn, T

1996-05-01

The purpose of this presentation is to help you reduce the inventory in your operation. We will accomplish that task by discussing six specific methods that companies have used successfully to reduce their inventory. One common attribute of these successes is that they also build teamwork among the people. Every business operation today is concerned with methods to improve customer service. The real trick is to accomplish that task without increasing inventory. We are all concerned with improving our skills at keeping inventory low.

Why the CDM can reduce carbon leakage

International Nuclear Information System (INIS)

Kallbekken, S.

2006-04-01

Carbon leakage is an important concern because it can reduce the environmental effectiveness of the Kyoto Protocol. The Clean Development Mechanism, one of the flexibility mechanisms allowed under the protocol, has the potential to reduce carbon leakage significantly because it reduces the relative competitive disadvantage to Annex B countries of restricting greenhouse gas emissions. The economic intuition behind this mechanism is explored in a theoretical analysis. It is then analyzed numerically using a CGE model. The results indicate that, assuming appropriate accounting for leakage and under realistic assumptions on CDM activity, the CDM has the potential to reduce the magnitude of carbon leakage by around three fifths

States reducing solar's soft costs

Energy Technology Data Exchange (ETDEWEB)

Meehan, Chris

2012-07-01

In 2012 the costs of modules will drop below the balance of system costs or 'soft costs' of solar in the US. Federal policy that nationalizes permitting processes could reduce some of the soft costs, but is unlikely. That's why states like California, Colorado, Connecticut and Vermont passed own laws to reduce soft costs by speeding solar permitting and reducing fees. (orig.)

Is lowering reducing sugars concentration in French fries an effective measure to reduce acrylamide concentration in food service establishments?

Science.gov (United States)

Sanny, M; Jinap, S; Bakker, E J; van Boekel, M A J S; Luning, P A

2012-12-01

The objective of this study was to obtain insight into the actual effectiveness of lowering reducing sugars concentration in par-fried potato strips on the concentration and variation of acrylamide in French fries prepared in real-life situations in food service establishments. Acrylamide, frying time, frying temperature, and reducing sugars were measured and characteristics of fryers were recorded. Data showed that the use of par-fried potato strips with lower concentrations of reducing sugars than the commonly used potato strips was an effective measure to reduce acrylamide concentrations in French fries prepared under standardised frying conditions. However, there was still large variation in the acrylamide concentrations in French fries, although the variation in reducing sugars concentrations in low and normal types of par-fried potato strips was very small and the frying conditions were similar. Factors that could affect the temperature-time profile of frying oil were discussed, such as setting a lower frying temperature at the end than at the start of frying, product/oil ratio and thawing practice. These need to be controlled in daily practice to reduce variation in acrylamide. Copyright © 2012 Elsevier Ltd. All rights reserved.

Characterization of Fe (III)-reducing enrichment culture and isolation of Fe (III)-reducing bacterium Enterobacter sp. L6 from marine sediment.

Science.gov (United States)

Liu, Hongyan; Wang, Hongyu

2016-07-01

To enrich the Fe (III)-reducing bacteria, sludge from marine sediment was inoculated into the medium using Fe (OH)3 as the sole electron acceptor. Efficiency of Fe (III) reduction and composition of Fe (III)-reducing enrichment culture were analyzed. The results indicated that the Fe (III)-reducing enrichment culture with the dominant bacteria relating to Clostridium and Enterobacter sp. had high Fe (III) reduction of (2.73 ± 0.13) mmol/L-Fe (II). A new Fe (III)-reducing bacterium was isolated from the Fe (III)-reducing enrichment culture and identified as Enterobacter sp. L6 by 16S rRNA gene sequence analysis. The Fe (III)-reducing ability of strain L6 under different culture conditions was investigated. The results indicated that strain L6 had high Fe (III)-reducing activity using glucose and pyruvate as carbon sources. Strain L6 could reduce Fe (III) at the range of NaCl concentrations tested and had the highest Fe (III) reduction of (4.63 ± 0.27) mmol/L Fe (II) at the NaCl concentration of 4 g/L. This strain L6 could reduce Fe (III) with unique properties in adaptability to salt variation, which indicated that it can be used as a model organism to study Fe (III)-reducing activity isolated from marine environment. Copyright © 2015 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

The Gambling Reducing Slot Machine

DEFF Research Database (Denmark)

Callesen, Mette Buhl; Thomsen, Kristine Rømer; Linnet, Jakob

2007-01-01

  The Gambling Reducing Slot Machine - Preliminary results Mette Buhl Callesen, Kristine Rømer Thomsen, Jakob Linnet and Arne Møller The PET Centre, Aarhus University Hospital and Centre of Functionally Integrative Neuroscience, Aarhus, Denmark   Slot machines are among the most addictive forms...... and willingness to continue gambling. The results may have important implications for understanding how to reduce gambling behavior in pathological gamblers.   [1] Griffiths, M. 1999. Gambling Technologies: Prospects for Problem Gambling. Journal of Gambling Studies, vol. 15(3), pp. 265-283.    ...

Characterization of methanotrophic bacteria on the basis of intact phospholipid profiles.

Science.gov (United States)

Fang, J; Barcelona, M J; Semrau, J D

2000-08-01

The intact phospholipid profiles (IPPs) of seven species of methanotrophs from all three physiological groups, type I, II and X, were determined using liquid chromatography/electrospray ionization/mass spectrometry. In these methanotrophs, two major classes of phospholipids were found, phosphatidylglycerol (PG) and phosphatidylethanolamine (PE) as well as its derivatives phosphatidylmethylethanolamine (PME) and phosphatidyldimethylethanolamine (PDME). Specifically, the type I methanotrophs, Methylomonas methanica, Methylomonas rubra and Methylomicrobium album BG8 were characterized by PE and PG phospholipids with predominantly C16:1 fatty acids. The type II methanotrophs, Methylosinus trichosporium OB3b and CSC1 were characterized by phospholipids of PG, PME and PDME with predominantly C18:1 fatty acids. Methylococcus capsulatus Bath, a representative of type X methanotrophs, contained mostly PE (89% of the total phospholipids). Finally, the IPPs of a recently isolated acidophilic methanotroph, Methylocella palustris, showed it had a preponderance of PME phospholipids with 18:1 fatty acids (94% of total). Principal component analysis showed these methanotrophs could be clearly distinguished based on phospholipid profiles. Results from this study suggest that IPP can be very useful in bacterial chemotaxonomy.

[Comparative characterization of cultured methane-oxidizing bacteria by serological and molecular methods].

Science.gov (United States)

Slobodova, N V; Kolganova, T V; Bulygina, E S; Kuznetsov, B B; Turova, T P; Kravchenko, I K

2006-01-01

Three stable methane-oxidizing enrichment cultures, SB26, SB31, and SB31A were analyzed by transmission electron microscopy and by serological and molecular techniques. Electron microscopy revealed the presence of both type I and type II methanotrophs in SB31 and SB31A enrichments; only type II methanotrophs were found in SB26 enrichment. Methylosinus trichosporium was detected in all three enrichments by the application of species-specific antibodies. Additionally, Methylocystis echinoides was found in SB26 culture; Methylococcus capsulatus, in SB31 and SB31A; and Methylomonas methanica, in SB31. The analysis with pmoA and nifH gene sequences as phylogenetic markers revealed the presence of Methylosinus/Methylocystis group in all communities. Moreover, the analysis of pmoA sequences revealed the presence of Methylomonas in SB31. Methylocella was detected in SB31 and SB31A enrichments only by nifH analysis. It was concluded that the simultaneous application of different approaches reveals more reliable information on the diversity of methanotrophs.

Reduced Pain Sensation and Reduced BOLD Signal in Parietofrontal Networks during Religious Prayer

DEFF Research Database (Denmark)

Elmholdt, Else-Marie; Skewes, Joshua Charles; Dietz, Martin

2017-01-01

Previous studies suggest that religious prayer can alter the experience of pain via expectation mechanisms. While brain processes related to other types of top-down modulation of pain have been studied extensively, no research has been conducted on the potential effects of active religious coping....... Here, we aimed at investigating the neural mechanisms during pain modulation by prayer and their dependency on the opioidergic system. Twenty-eight devout Protestants performed religious prayer and a secular contrast prayer during painful electrical stimulation in two fMRI sessions. Naloxone or saline...... was administered prior to scanning. Results show that pain intensity was reduced by 11% and pain unpleasantness by 26% during religious prayer compared to secular prayer. Expectancy predicted large amounts (70–89%) of the variance in pain intensity. Neuroimaging results revealed reduced neural activity during...

Reduced kinetic equations: An influence functional approach

International Nuclear Information System (INIS)

Wio, H.S.

1985-01-01

The author discusses a scheme for obtaining reduced descriptions of multivariate kinetic equations based on the 'influence functional' method of Feynmann. It is applied to the case of Fokker-Planck equations showing the form that results for the reduced equation. The possibility of Markovian or non-Markovian reduced description is discussed. As a particular example, the reduction of the Kramers equation to the Smoluchwski equation in the limit of high friction is also discussed

Monitoring sequential electron transfer with EPR

International Nuclear Information System (INIS)

Thurnauer, M.C.; Feezel, L.L.; Snyder, S.W.; Tang, J.; Norris, J.R.; Morris, A.L.; Rustandi, R.R.

1989-01-01

A completely general model which treats electron spin polarization (ESP) found in a system in which radical pairs with different magnetic interactions are formed sequentially has been described. This treatment has been applied specifically to the ESP found in the bacterial reaction center. Test cases show clearly how parameters such as structure, lifetime, and magnetic interactions within the successive radical pairs affect the ESP, and demonstrate that previous treatments of this problem have been incomplete. The photosynthetic bacterial reaction center protein is an ideal system for testing the general model of ESP. The radical pair which exhibits ESP, P 870 + Q - (P 870 + is the oxidized, primary electron donor, a bacteriochlorophyll special pair and Q - is the reduced, primary quinone acceptor) is formed via sequential electron transport through the intermediary radical pair P 870 + I - (I - is the reduced, intermediary electron acceptor, a bacteriopheophytin). In addition, it is possible to experimentally vary most of the important parameters, such as the lifetime of the intermediary radical pair and the magnetic interactions in each pair. It has been shown how selective isotopic substitution ( 1 H or 2 H) on P 870 , I and Q affects the ESP of the EPR spectrum of P 870 + Q - , observed at two different microwave frequencies, in Fe 2+ -depleted bacterial reaction centers of Rhodobacter sphaeroides R26. Thus, the relative magnitudes of the magnetic properties (nuclear hyperfine and g-factor differences) which influence ESP development were varied. The results support the general model of ESP in that they suggest that the P 870 + Q - radical pair interactions are the dominant source of ESP production in 2 H bacterial reaction centers

Hydrothermal synthesis of magnetic reduced graphene oxide sheets

International Nuclear Information System (INIS)

Shen, Jianfeng; Shi, Min; Ma, Hongwei; Yan, Bo; Li, Na; Ye, Mingxin

2011-01-01

Graphical abstract: An environmental friendly and efficient route for preparation of magnetic reduced graphene oxide composite with a one-step hydrothermal method was demonstrated. The reducing process was accompanied by generation of magnetic nanoparticles. Highlights: → A one-step hydrothermal method for preparation of MN-CCG was demonstrated. → Glucose was used as the 'green' reducing agent. → The reducing process was accompanied by generation of magnetic nanoparticles. → The prepared MN-CCG is highly water suspendable and sensitive to magnetic field. -- Abstract: We demonstrated an environmental friendly and efficient route for preparation of magnetic reduced graphene oxide composite (MN-CCG). Glucose was used as the reducing agent in this one-step hydrothermal method. The reducing process was accompanied by generation of magnetic nanoparticles. The structure and composition of the nanocomposite was confirmed by Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray diffraction, thermal gravimetric analysis, atomic force microscopy and transmission electron microscopy. It was found that the prepared MN-CCG is highly water suspendable and sensitive to magnetic field.

Generalized Reduced Order Model Generation, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — M4 Engineering proposes to develop a generalized reduced order model generation method. This method will allow for creation of reduced order aeroservoelastic state...

Patient experiences with interventions to reduce surgery cancellations

DEFF Research Database (Denmark)

Hovlid, Einar; von Plessen, Christian; Haug, Kjell

2013-01-01

The cancellation of planned surgery harms patients, increases waiting times and wastes scarce health resources. Previous studies have evaluated interventions to reduce cancellations from medical and management perspectives; these have focused on cost, length of stay, improved efficiency......, and reduced post-operative complications. In our case a hospital had experienced high cancellation rates and therefore redesigned their pathway for elective surgery to reduce cancelations. We studied how patients experienced interventions to reduce cancellations....

Evolution of technetium speciation in reducing grout

Energy Technology Data Exchange (ETDEWEB)

Lukens, Wayne W.; Bucher, Jerome J.; Shuh, David K.; Edelstein,Norman M.

2003-11-24

Cementitious waste forms (CWFs) are an important component of the strategy to immobilize high-level nuclear waste resulting from plutonium production by the U.S. Department of Energy (DOE). Technetium (99Tc) is an abundant fission product of particular concern in CWFs due to the high solubility and mobility of pertechnetate, TcO4-, the stable form of technetium in aerobic environments. CWFs can more effectively immobilize 99Tc if they contain additives that reduce mobile TcO4- to immobile Tc(IV) species. Leaching of 99Tc from reducing CWFs that contain Tc(IV) is much slower than for CWFs containing TcO4-. Previous X-ray absorption fine structure (XAFS) studies showed that the Tc(IV) species were oxidized to TcO4- in reducing grout samples prepared on a laboratory scale. Whether the oxidizer was atmospheric O2 or NO3- in the waste simulant was not determined. In actual CWFs, rapid oxidation of Tc(IV) by NO3- would be a concern, whereas oxidation by atmospheric O2 would be of less concern due to the slow diffusion and reaction of O2 with the reducing CWF. To address this uncertainty, two series of reducing grouts were prepared using TcO4- containing waste simulants with and without NO3-. In the first series of samples, the TcO4- was completely reduced using Na2S, and the samples were placed in containers that permitted O2 diffusion. In these samples, all of the technetium was initially present as aTc(IV) sulfide compound, TcSx, which was characterized using extended X-ray absorption fine structure (EXAFS) spectroscopy, and is likely Tc2S7. The TcSx initially present in the grout samples was steadily oxidized over 4 years. In the second series of samples, all of the TcO4- was not initially reduced, and the grout samples were placed in airtight containers. In these samples, the remaining TcO4- continued to be reduced as the samples aged, presumably due to the presence of reducing blast furnace slag. When samples in the second series were exposed to atmosphere, the

Syntheses of sup 18 F-labeled reduced haloperidol and sup 11 C-labeled reduced 3-N-methylspiperone

Energy Technology Data Exchange (ETDEWEB)

Ravert, H T; Dannals, R F; Wilson, A A; Wong, D F; Wagner, Jr, H N [Johns Hopkins Medical Institutions, Baltimore, MD (USA)

1991-03-01

{sup 18}F-Labeled reduced haloperidol and {sup 11}C-labeled reduced 3-N-methylspiperone were synthesized in a convenient and quantitative one step reduction from {sup 18}F-labeled haloperidol and {sup 11}C-labeled N-methylspiperone, respectively. Both products were purified by semipreparative HPLC and were obtained at high specific activity and radiochemical purity. (author).

Quantum Entanglement and Reduced Density Matrices

Science.gov (United States)

Purwanto, Agus; Sukamto, Heru; Yuwana, Lila

2018-05-01

We investigate entanglement and separability criteria of multipartite (n-partite) state by examining ranks of its reduced density matrices. Firstly, we construct the general formula to determine the criterion. A rank of origin density matrix always equals one, meanwhile ranks of reduced matrices have various ranks. Next, separability and entanglement criterion of multipartite is determined by calculating ranks of reduced density matrices. In this article we diversify multipartite state criteria into completely entangled state, completely separable state, and compound state, i.e. sub-entangled state and sub-entangledseparable state. Furthermore, we also shorten the calculation proposed by the previous research to determine separability of multipartite state and expand the methods to be able to differ multipartite state based on criteria above.

Reduced-activation steels: present status and future development

International Nuclear Information System (INIS)

Klueh, R.L.

2007-01-01

Full text of publication follows: Reduced-activation steels for fusion reactor applications were developed in the 1980's to replace the commercial elevated- temperature steels first considered. In the United States, this involved replacing Sandvik HT9 and modified 9Cr-1Mo steels. Reduced-activation steels, which were developed for more rapid radioactivity decay following exposure in a fusion neutron environment, were patterned after the commercial steels they were to replace. The objective for the reduced-activation steels was that they have strengths (yield stress and ultimate tensile strength from room temperature to 600 deg. C) and impact toughness (measured in a Charpy test) comparable to or better than the steels they were replacing. That objective was achieved in reduced-activation steels developed in Japan, Europe, and the United States. Since the reduced-activation steels were developed in the 1980's, reactor designers have been interested designs for increased efficiency of future fusion plants. This means reactors will need to operate at higher temperatures-above 550 deg. C, which is the upper-temperature limit for the reduced-activation steels. Although the tensile and impact toughness of the reduced-activation steels exceed those of the commercial steels they were patterned after, their creep-rupture properties are inferior to some of the commercial steels they replaced. furthermore, they are much inferior to commercial steels that have been developed since the 1980's. Reasons for why the creep-rupture properties for the new commercial ferritic/martensitic steels are superior to the earlier commercial steels and the reduced-activation steels were examined. The reasons involve compositional changes that were made in the earlier commercial steels to give the new commercial steels their superior properties. Computational thermodynamics calculations were carried out to compare the expected equilibrium phases. It appears that similar changes in composition

Quasi-equilibria in reduced Liouville spaces.

Science.gov (United States)

Halse, Meghan E; Dumez, Jean-Nicolas; Emsley, Lyndon

2012-06-14

The quasi-equilibrium behaviour of isolated nuclear spin systems in full and reduced Liouville spaces is discussed. We focus in particular on the reduced Liouville spaces used in the low-order correlations in Liouville space (LCL) simulation method, a restricted-spin-space approach to efficiently modelling the dynamics of large networks of strongly coupled spins. General numerical methods for the calculation of quasi-equilibrium expectation values of observables in Liouville space are presented. In particular, we treat the cases of a time-independent Hamiltonian, a time-periodic Hamiltonian (with and without stroboscopic sampling) and powder averaging. These quasi-equilibrium calculation methods are applied to the example case of spin diffusion in solid-state nuclear magnetic resonance. We show that there are marked differences between the quasi-equilibrium behaviour of spin systems in the full and reduced spaces. These differences are particularly interesting in the time-periodic-Hamiltonian case, where simulations carried out in the reduced space demonstrate ergodic behaviour even for small spins systems (as few as five homonuclei). The implications of this ergodic property on the success of the LCL method in modelling the dynamics of spin diffusion in magic-angle spinning experiments of powders is discussed.

Reduced intrinsic heart rate is associated with reduced arrhythmic susceptibility in guinea-pig heart.

Science.gov (United States)

Osadchii, Oleg E

2014-12-01

In the clinical setting, patients with slower resting heart rate are less prone to cardiovascular death compared with those with elevated heart rate. However, electrophysiological adaptations associated with reduced cardiac rhythm have not been thoroughly explored. In this study, relationships between intrinsic heart rate and arrhythmic susceptibility were examined by assessments of action potential duration (APD) rate adaptation and inducibility of repolarization alternans in sinoatrial node (SAN)-driven and atrioventricular (AV)-blocked guinea-pig hearts perfused with Langendorff apparatus. Electrocardiograms, epicardial monophasic action potentials, and effective refractory periods (ERP) were assessed in normokalemic and hypokalemic conditions. Slower basal heart rate in AV-blocked hearts was associated with prolonged ventricular repolarization during spontaneous beating, and with attenuated APD shortening at increased cardiac activation rates during dynamic pacing, when compared with SAN-driven hearts. During hypokalemic perfusion, the inducibility of repolarization alternans and tachyarrhythmia by rapid pacing was found to be lower in AV-blocked hearts. This difference was ascribed to prolonged ERP in the setting of reduced basal heart rate, which prevented ventricular capture at critically short pacing intervals required to induce arrhythmia. Reduced basal heart rate is associated with electrophysiological changes that prevent electrical instability upon an abrupt cardiac acceleration.

Mitochondrial Respiration Is Reduced in Atherosclerosis, Promoting Necrotic Core Formation and Reducing Relative Fibrous Cap Thickness.

Science.gov (United States)

Yu, Emma P K; Reinhold, Johannes; Yu, Haixiang; Starks, Lakshi; Uryga, Anna K; Foote, Kirsty; Finigan, Alison; Figg, Nichola; Pung, Yuh-Fen; Logan, Angela; Murphy, Michael P; Bennett, Martin

2017-12-01

Mitochondrial DNA (mtDNA) damage is present in murine and human atherosclerotic plaques. However, whether endogenous levels of mtDNA damage are sufficient to cause mitochondrial dysfunction and whether decreasing mtDNA damage and improving mitochondrial respiration affects plaque burden or composition are unclear. We examined mitochondrial respiration in human atherosclerotic plaques and whether augmenting mitochondrial respiration affects atherogenesis. Human atherosclerotic plaques showed marked mitochondrial dysfunction, manifested as reduced mtDNA copy number and oxygen consumption rate in fibrous cap and core regions. Vascular smooth muscle cells derived from plaques showed impaired mitochondrial respiration, reduced complex I expression, and increased mitophagy, which was induced by oxidized low-density lipoprotein. Apolipoprotein E-deficient (ApoE -/- ) mice showed decreased mtDNA integrity and mitochondrial respiration, associated with increased mitochondrial reactive oxygen species. To determine whether alleviating mtDNA damage and increasing mitochondrial respiration affects atherogenesis, we studied ApoE -/- mice overexpressing the mitochondrial helicase Twinkle (Tw + /ApoE -/- ). Tw + /ApoE -/- mice showed increased mtDNA integrity, copy number, respiratory complex abundance, and respiration. Tw + /ApoE -/- mice had decreased necrotic core and increased fibrous cap areas, and Tw + /ApoE -/- bone marrow transplantation also reduced core areas. Twinkle increased vascular smooth muscle cell mtDNA integrity and respiration. Twinkle also promoted vascular smooth muscle cell proliferation and protected both vascular smooth muscle cells and macrophages from oxidative stress-induced apoptosis. Endogenous mtDNA damage in mouse and human atherosclerosis is associated with significantly reduced mitochondrial respiration. Reducing mtDNA damage and increasing mitochondrial respiration decrease necrotic core and increase fibrous cap areas independently of changes in

Experimental knee pain reduces muscle strength

DEFF Research Database (Denmark)

Henriksen, Marius; Mortensen, Sara Rosager; Aaboe, Jens

2011-01-01

Pain is the principal symptom in knee pathologies and reduced muscle strength is a common observation among knee patients. However, the relationship between knee joint pain and muscle strength remains to be clarified. This study aimed at investigating the changes in knee muscle strength following...... experimental knee pain in healthy volunteers, and if these changes were associated with the pain intensities. In a crossover study, 18 healthy subjects were tested on 2 different days. Using an isokinetic dynamometer, maximal muscle strength in knee extension and flexion was measured at angular velocities 0....... Knee pain reduced the muscle strength by 5 to 15% compared to the control conditions (P knee extension and flexion at all angular velocities. The reduction in muscle strength was positively correlated to the pain intensity. Experimental knee pain significantly reduced knee extension...

Sucralfate significantly reduces ciprofloxacin concentrations in serum.

OpenAIRE

Garrelts, J C; Godley, P J; Peterie, J D; Gerlach, E H; Yakshe, C C

1990-01-01

The effect of sucralfate on the bioavailability of ciprofloxacin was evaluated in eight healthy subjects utilizing a randomized, crossover design. The area under the concentration-time curve from 0 to 12 h was reduced from 8.8 to 1.1 micrograms.h/ml by sucralfate (P less than 0.005). Similarly, the maximum concentration of ciprofloxacin in serum was reduced from 2.0 to 0.2 micrograms/ml (P less than 0.005). We conclude that concurrent ingestion of sucralfate significantly reduces the concentr...

Low Nonfasting Triglycerides and Reduced All-Cause Mortality

DEFF Research Database (Denmark)

Thomsen, Mette; Varbo, Anette; Tybjærg-Hansen, Anne

2014-01-01

BACKGROUND: Increased nonfasting plasma triglycerides marking increased amounts of cholesterol in remnant lipoproteins are important risk factors for cardiovascular disease, but whether lifelong reduced concentrations of triglycerides on a genetic basis ultimately lead to reduced all......-cause mortality is unknown. We tested this hypothesis. METHODS: Using individuals from the Copenhagen City Heart Study in a mendelian randomization design, we first tested whether low concentrations of nonfasting triglycerides were associated with reduced all-cause mortality in observational analyses (n = 13 957......); second, whether genetic variants in the triglyceride-degrading enzyme lipoprotein lipase, resulting in reduced nonfasting triglycerides and remnant cholesterol, were associated with reduced all-cause mortality (n = 10 208). RESULTS: During a median 24 and 17 years of 100% complete follow-up, 9991...

Reducing consumption through communal living

Energy Technology Data Exchange (ETDEWEB)

Herring, Horace [The Open Univ., Milton Keynes (United Kingdom). Energy and Environment Research Unit

2003-07-01

This paper examines ways consumers and communities can voluntarily adopt a low consumption (or low carbon) lifestyle, often termed 'voluntary simplicity' or a policy of 'sufficiency'. There is an increasing academic literature within Europe in the last five years on the whole question of 'sustainable consumption', and the relationship between income levels and consumption particularly at the household. This debate has moved beyond 'green consumerism' to look at building 'new concepts of prosperity' through local community actions, or reducing working time to allow more time for the creation of social capital. The paper will concentrate on one aspect of the quest for sustainable communities, the relevance of communal living to reducing consumption through examining energy consumption (both direct and indirect) in one such community in the UK. The results from this preliminary study reveal that it is not the sharing of resources that reduces consumption but the mutual reinforcement of attitudes towards a low consumption lifestyle. Thus it is the creation of social capital in a community that is its key to its ecological lifestyle.

Boiler burden reduced at Bedford site.

Science.gov (United States)

Horsley, Chris

2011-10-01

With the NHS aiming to reduce its 2007 carbon footprint by 10% by 2015, Chris Horsley, managing director of Babcock Wanson UK, a provider of industrial boilers and burners, thermal oxidisers, air treatment, water treatment, and associated services, looks at how one NHS Trust has approached the challenge, and considerably reduced its carbon emissions, by refurbishing its boiler house and moving from oil to gas-fired steam generation.

Boundaries, injective envelopes, and reduced crossed products

DEFF Research Database (Denmark)

Bryder, Rasmus Sylvester

In this dissertation, we study boundary actions, equivariant injective envelopes, as well as theideal structure of reduced crossed products. These topics have recently been linked to thestudy of C-simple groups, that is, groups with simple reduced group C-algebras.In joint work with Matthew Kennedy......, we consider reduced twisted crossed products overC-simple groups. For any twisted C-dynamical system over a C-simple group, we provethat there is a one-to-one correspondence between maximal invariant ideals in the underlyingC-algebra and maximal ideals in the reduced crossed product. When......*-algebras, and relate the intersection property for group actions on unital C*-algebras to the intersection property for theequivariant injective envelope. Moreover, we also prove that the equivariant injective envelopeof the centre of the injective envelope of a unital C*-algebra can be regarded as a C...

Synthesis of battery grade reduced silver powder

International Nuclear Information System (INIS)

Qadeer, R.; Hameed, M.; Ikram, S.; Munir, A.

2002-01-01

Process for production of battery grade reduced silver powder, an active positive material for zinc-silver oxide batteries, having specific characteristics has been optimized and the synthesized reduced silver powder was characterized. Results reveal that the values of bulk density (1.25 0.1 g/cm3) and activity (73.27 %) of synthesized reduced silver powder lies within the recommended range for use as battery material. It has purity ≥ 98% and contains Fe and Cu as traces in the concentration range of 30 5 ppm and 15 7 ppm respectively. Others determined values of surface and pores parameters are: surface area 2.6 .4 m2/g: pore volume 3.10 cm3/g: pore diameter 0.043 mu m and porosity 20%. XRD studies reveal that reduced silver powder has a cubic structure. (author)

Reiki Reduces Burnout Among Community Mental Health Clinicians.

Science.gov (United States)

Rosada, Renee M; Rubik, Beverly; Mainguy, Barbara; Plummer, Julie; Mehl-Madrona, Lewis

2015-08-01

Clinicians working in community mental health clinics are at high risk for burnout. Burnout is a problem involving emotional exhaustion, depersonalization, and reduced personal accomplishment. Reiki is a holistic biofield energy therapy beneficial for reducing stress. The purpose of this study was to determine if 30 minutes of healing touch could reduce burnout in community mental health clinicians. We utilized a crossover design to explore the efficacy of Reiki versus sham Reiki, a pseudo treatment designed to mimic true Reiki, as a means to reduce symptoms of burnout. Subjects were randomized to whether they started with Reiki or sham. The Maslach Burnout Inventory-Human Services Survey (MBI-HSS) and the Measure Your Medical Outcome Profile Version 2 (MYMOP-2) were used as outcome measures. Multilevel modeling was used to represent the relations among variables. Reiki was statistically significantly better than sham Reiki in reducing burnout among community mental health clinicians (p=0.011). Reiki was significant in reducing depersonalization (pReiki reduced the primary symptom on the MYMOP also only among single people (p=0.03). The effects of Reiki were differentiated from sham Reiki. Reiki could be helpful in community mental health settings for the mental health of the practitioners.

Reduced-density-matrix theory and algebraic structures

International Nuclear Information System (INIS)

Kryachko, E.S.

1978-01-01

A survey of recent work on algebraic structures and reduced-density-matrix theory is presented. The approach leads to a method of classifying reduced density matrices and generalizes the notion of open and closed shells in many-body theory. 6 references

Reducing methane emissions from ruminant animals

Energy Technology Data Exchange (ETDEWEB)

Mathison, G.W.; Okine, E.K.; McAllister, T.A.; Dong, Y.; Galbraith, J.; Dmytruk, O.I.N. [University of Alberta, Edmonton, AB (Canada). Dept. of Agriculture, Food and Nutrition Science

1998-09-01

In 1992 it was estimated that 30 x 10{sup 12}g more methane was emitted into the atmosphere than was removed, with animals being considered the largest single anthropogenic source. Ruminants produce 97% of the methane generated in enteric fermentation by animals. Estimates for methane emissions from animal wastes vary between 6 and 31% of that produced directly by the animal, with the most likely value being between 5 and 10% globally. Methane inhibitors can reduce methane emissions to zero in the short term but due to microbial adaptation the effects of these compounds are quickly neutralized and feed intake is often depressed. Methane emissions per unit of feed consumed from sheep and cattle fed hay diets appear to be quite similar but differences between other ruminants have been measured. The most practical way of influencing methane emissions per unit product is to increase productivity level since the proportion of feed energy required to just maintain the animal will be reduced, methane production falls with increased intake level, and the animal may go to market sooner. The most promising avenues for future research for reducing methanogenesis are the development of new products for reducing protozoal numbers in the rumen and the use of bacterocins or other compounds which specifically target methanogenic bacteria.

Reducing the risk of nuclear terrorism

International Nuclear Information System (INIS)

Hibbs, R.

2005-01-01

Full text: The March 2005 'International conference on nuclear security, global directions for the future' noted that nuclear terrorism is one of the greatest threats to society. Eminent members of a multi-national panel stated that there is no one principal activity to reduce the risk of nuclear terrorism and that a combination of activities is required. This paper seeks to identify those activities by analyzing the elements that comprise the risk of nuclear terrorism. For the purpose of the analysis, risk is the product of the probability of a terrorist attack (A p ), the success of a terrorist act (S p ) and the consequence (C) of the attack: R=A p * S p * C. The paper examines each of these three elements of risk with the objective of identifying what we are doing and what else we could be doing to reduce risk. It takes into consideration some historic catastrophes, examines how they might have been prevented or their consequences reduced, and if there are lessons that are applicable to reducing the risk of nuclear terrorism. The paper demonstrates that we have concentrated on only one of the three elements of risk and offer suggestions for diminishing the risk of nuclear terrorism by addressing all the elements. (author)

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

ENDOR data suggests that the special-pair radical cation P + from Rhodobacter sphaeroides is 68% localized on P L while simple interpretations of FTIR difference spectra based primarily on intensity information, but to some extent also bandwidths, suggest near-complete charge localization. We provide a complete a priori spectral simulation of the spectrum of P + in the range 0-5000 cm-1, including explicit treatment of the high-resolution vibrational transitions, the low-resolution hole-transfer absorption centered at 2700 cm-1, and the resonance with the SHOMO to HOMO transition at 2200 cm-1 that resolve the issues concerning the nature of P + . The description of the vibrational aspects of the problem were taken from results of previous density-functional calculations, and a qualitatively realistic large number of vibrational modes (50 antisymmetric and 18-20 symmetric) were included. To facilitate the calculations, a new representation of the vibronic-coupling Hamiltonian for intervalence hole-transfer or electron-transfer problems is introduced, allowing the spectrum to be simulated efficiently using only up to 4x10 9 vibronic basis functions and leading also to new general analytical relationships. Observed spectra are fitted using seven adjustable chemical parameters describing the interactions between the four electronic states involved. The resulting fits provide unique descriptions of the parameters that are insensitive to the source of the observed spectrum or the nature of the symmetric modes used in the model, and all fitted parameters are found to be close in value to those from independent estimates. We determine the electronic coupling, antisymmetric-mode reorganization energy, and redox asymmetry to be J=0.126±0.002 eV, λ=0.139±0.003 eV, and E 0 =0.069±0.002 eV, respectively. Our description forms the basis of understanding for a wide range of other properties observed for Rhodobacter sphaeroides mutants, as well as the properties of the

Do Workplace Smoking Bans Reduce Smoking?

OpenAIRE

Matthew C. Farrelly; William N. Evans; Edward Montgomery

1999-01-01

In recent years there has been a heightened public concern over the potentially harmful effects of environmental tobacco smoke (ETS). In response, smoking has been banned on many jobs. Using data from the 1991 and 1993 National Health Interview Survey and smoking supplements to the September 1992 and May 1993 Current Population Survey, we investigate whether these workplace policies reduce smoking prevalence and smoking intensity among workers. Our estimates suggest that workplace bans reduce...

21 CFR 184.1979a - Reduced lactose whey.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Reduced lactose whey. 184.1979a Section 184.1979a... Listing of Specific Substances Affirmed as GRAS § 184.1979a Reduced lactose whey. (a) Reduced lactose whey is the substance obtained by the removal of lactose from whey. The lactose content of the finished...

21 CFR 184.1979b - Reduced minerals whey.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Reduced minerals whey. 184.1979b Section 184.1979b... Listing of Specific Substances Affirmed as GRAS § 184.1979b Reduced minerals whey. (a) Reduced minerals whey is the substance obtained by the removal of a portion of the minerals from whey. The dry product...

Analysis on Dynamic Transmission Accuracy for RV Reducer

Directory of Open Access Journals (Sweden)

Zhang Fengshou

2017-01-01

Full Text Available By taking rotate vector (RV reducer as the research object, the factors affecting the transmission accuracy are studied, including the machining errors of the main parts, assembly errors, clearance, micro-displacement, gear mesh stiffness and damping, bearing stiffness. Based on Newton second law, the transmission error mathematical model of RV reducer is set up. Then, the RV reducer transmission error curve is achieved by solving the mathematical model using the Runge-Kutta methods under the combined action of various error factors. Through the analysis of RV reducer transmission test, it can be found that there are similar variation trend and frequency components compared the theoretical research and experimental result. The presented method is useful to the research on dynamic transmission accuracy of RV reducer, and also applies to research the transmission accuracy of other cycloid drive systems.

Absorbance changes accompanying the fast fluorescence induction in the purple bacterium Rhodobacter sphaeroides

Czech Academy of Sciences Publication Activity Database

Bína, David; Litvín, Radek; Vácha, František

2010-01-01

Roč. 105, č. 2 (2010), s. 115-121 ISSN 0166-8595 R&D Projects: GA AV ČR IAA608170603 Institutional research plan: CEZ:AV0Z50510513 Keywords : Photosynthesis * Charge separation * Membrane potential Subject RIV: CE - Biochemistry Impact factor: 2.410, year: 2010

Blind Reduced-Rank MMSE Detector for DS-CDMA Systems

Directory of Open Access Journals (Sweden)

Xiaodong Cai

2003-01-01

Full Text Available We first develop a reduced-rank minimum mean squared error (MMSE detector for direct-sequence (DS code division multiple access (CDMA by forcing the linear MMSE detector to lie in a signal subspace of a reduced dimension. While a reduced-rank MMSE detector has lower complexity, it cannot outperform the full-rank MMSE detector. We then concentrate on the blind reduced-rank MMSE detector which is obtained from an estimated covariance matrix. Our analysis and simulation results show that when the desired user′s signal is in a low-dimensional subspace, there exists an optimal subspace so that the blind reduced-rank MMSE detector lying in this subspace has the best performance. By properly choosing a subsspace, we guarantee that the optimal blind reduced-rank MMSE detector is obtained. An adaptive blind reduced-rank MMSE detector, based on a subspace tracking algorithm, is developed. The adaptive blind reduced-rank MMSE detector exhibits superior steady-state performance and fast convergence speed.

Reduced embodied simulation in psychopathy.

Science.gov (United States)

Mier, Daniela; Haddad, Leila; Diers, Kersten; Dressing, Harald; Meyer-Lindenberg, Andreas; Kirsch, Peter

2014-08-01

Psychopathy is characterized by severe deficits in emotion processing and empathy. These emotional deficits might not only affect the feeling of own emotions, but also the understanding of others' emotional and mental states. The present study aims on identifying the neurobiological correlates of social-cognitive related alterations in psychopathy. We applied a social-cognitive paradigm for the investigation of face processing, emotion recognition, and affective Theory of Mind (ToM) to 11 imprisoned psychopaths and 18 healthy controls. Functional magnetic resonance imaging was used to measure task-related brain activation. While showing no overall behavioural deficit, psychopathy was associated with altered brain activation. Psychopaths had reduced fusiform activation related to face processing. Related to affective ToM, psychopaths had hypoactivation in amygdala, inferior prefrontal gyrus and superior temporal sulcus, areas associated with embodied simulation of emotions and intentions. Furthermore, psychopaths lacked connectivity between superior temporal sulcus and amygdala during affective ToM. These results replicate findings of alterations in basal face processing in psychopathy. In addition, they provide evidence for reduced embodied simulation in psychopathy in concert with a lack of communication between motor areas and amygdala which might provide the neural substrate of reduced feeling with others during social cognition.

Reducing online identity disclosure using warnings.

Science.gov (United States)

Carpenter, Sandra; Zhu, Feng; Kolimi, Swapna

2014-09-01

In an experimental design, we tested whether written warnings can reduce the amount of identity information exposure online. A psychological attack on information privacy that has been shown to be effective in previous research was launched. This attack took advantage of the fact that people respond to certain types of requests in a relatively automatic, or mindless, fashion. The experiment manipulated the word that was used in the alert header: "warning", "caution", or "hazard". All warnings proved to be effective in reducing disclosure, but "hazard" proved to be most effective. Also warnings were more effective in reducing disclosure of driver's license numbers than email addresses. The discussion (a) provides tentative conclusions why these patterns were obtained, (b) suggests how to design warnings in cyber-environments, and (c) addresses future possibilities for research on this topic. Copyright © 2013 Elsevier Ltd and The Ergonomics Society. All rights reserved.

Extending OFDM Symbols to Reduce Power Consumption

NARCIS (Netherlands)

Kokkeler, Andre B.J.; Smit, Gerardus Johannes Maria

2012-01-01

Existing communication standards have limited capabilities to adapt to low SNR environments or to exploit low data rate requirements in a power efficient way. Existing techniques like e.g. control coding do not reduce the computational load when reducing data rates. In this paper, we introduce

Cogeneration, renewables and reducing greenhouse gas emissions

International Nuclear Information System (INIS)

Naughten, B.; Dlugosz, J.

1996-01-01

The MENSA model is used to assess the potential role of cogeneration and selected new renewable energy technologies in cost-effectively reducing Greenhouse gas emissions. The model framework for analyzing these issues is introduced, together with an account of relevant aspects of its application. In the discussion of selected new renewable energy technologies, it is shown how microeconomic reform may encourage these technologies and fuels, and thereby reduce sector wide carbon dioxide emissions. Policy scenarios modelled are described and the simulation results are presented. Certain interventions in microeconomic reform may result in economic benefits while also reducing emissions: no regrets' opportunities. Some renewable energy technologies are also shown to be cost-effective in the event that targets and timetables for reducing Greenhouse gas emissions are imposed. However, ad hoc interventions in support of particular renewables options are unlikely to be consistent with a least cost approach to achieving environmental objectives. (author). 5 tabs., 5 figs., 21 refs

Reduced Voltage Scaling in Clock Distribution Networks

Directory of Open Access Journals (Sweden)

Khader Mohammad

2009-01-01

Full Text Available We propose a novel circuit technique to generate a reduced voltage swing (RVS signals for active power reduction on main buses and clocks. This is achieved without performance degradation, without extra power supply requirement, and with minimum area overhead. The technique stops the discharge path on the net that is swinging low at a certain voltage value. It reduces active power on the target net by as much as 33% compared to traditional full swing signaling. The logic 0 voltage value is programmable through control bits. If desired, the reduced-swing mode can also be disabled. The approach assumes that the logic 0 voltage value is always less than the threshold voltage of the nMOS receivers, which eliminate the need of the low to high voltage translation. The reduced noise margin and the increased leakage on the receiver transistors using this approach have been addressed through the selective usage of multithreshold voltage (MTV devices and the programmability of the low voltage value.

Reduced Pms2 expression in non-neoplastic flat mucosa from patients with colon cancer correlates with reduced apoptosis competence.

Science.gov (United States)

Bernstein, Harris; Prasad, Anil; Holubec, Hana; Bernstein, Carol; Payne, Claire M; Ramsey, Lois; Dvorakova, Katerina; Wilson, Megan; Warneke, James A; Garewal, Harinder

2006-06-01

Pms2 protein is a component of the DNA mismatch repair complex responsible both for post-replication correction of DNA nucleotide mispairs and for early steps in apoptosis. Germline mutations in DNA mismatch repair genes give rise to hereditary non-polyposis colon cancer, which accounts for about 4% of colon cancers. However, little is known about the expression of mismatch repair proteins in relation to sporadic colon cancer, which accounts for the great majority of colon cancers. Multiple samples were taken from the non-neoplastic flat mucosa of colon resections from patients with no colonic neoplasia, a tubulovillous adenoma, or an adenocarcinoma. Expression of Pms2 was assessed using semiquantitative immunohistochemistry. Apoptosis was assessed in polychrome-stained epoxy sections using morphologic criteria. Samples from patients without colonic neoplasia had moderate to strong staining for Pms2 in cell nuclei at the base of crypts, while samples from 2 of the 3 colons with a tubulovillous adenoma, and from 6 of the 10 colons with adenocarcinomas, showed reduced Pms2 expression. Samples from patients with an adenocarcinoma that had reduced Pms2 expression also exhibited reduced apoptosis capability in nearby tissue samples, evidenced when this paired tissue was stressed ex vivo with bile acid. Reduced Pms2 expression in the colonic mucosa may be an early step in progression to colon cancer. This reduction may cause decreased mismatch repair, increased genetic instability, and/or reduced apoptotic capability. Immunohistochemical determination of reduced Pms2 expression, upon further testing, may prove to be a promising early biomarker of risk of progression to malignancy.

Reducing gravity takes the bounce out of running.

Science.gov (United States)

Polet, Delyle T; Schroeder, Ryan T; Bertram, John E A

2018-02-13

In gravity below Earth-normal, a person should be able to take higher leaps in running. We asked 10 subjects to run on a treadmill in five levels of simulated reduced gravity and optically tracked centre-of-mass kinematics. Subjects consistently reduced ballistic height compared with running in normal gravity. We explain this trend by considering the vertical take-off velocity (defined as maximum vertical velocity). Energetically optimal gaits should balance the energetic costs of ground-contact collisions (favouring lower take-off velocity), and step frequency penalties such as leg swing work (favouring higher take-off velocity, but less so in reduced gravity). Measured vertical take-off velocity scaled with the square root of gravitational acceleration, following energetic optimality predictions and explaining why ballistic height decreases in lower gravity. The success of work-based costs in predicting this behaviour challenges the notion that gait adaptation in reduced gravity results from an unloading of the stance phase. Only the relationship between take-off velocity and swing cost changes in reduced gravity; the energetic cost of the down-to-up transition for a given vertical take-off velocity does not change with gravity. Because lower gravity allows an elongated swing phase for a given take-off velocity, the motor control system can relax the vertical momentum change in the stance phase, thus reducing ballistic height, without great energetic penalty to leg swing work. Although it may seem counterintuitive, using less 'bouncy' gaits in reduced gravity is a strategy to reduce energetic costs, to which humans seem extremely sensitive. © 2018. Published by The Company of Biologists Ltd.

Reducible cationic lipids for gene transfer.

Science.gov (United States)

Wetzer, B; Byk, G; Frederic, M; Airiau, M; Blanche, F; Pitard, B; Scherman, D

2001-01-01

One of the main challenges of gene therapy remains the increase of gene delivery into eukaryotic cells. We tested whether intracellular DNA release, an essential step for gene transfer, could be facilitated by using reducible cationic DNA-delivery vectors. For this purpose, plasmid DNA was complexed with cationic lipids bearing a disulphide bond. This reduction-sensitive linker is expected to be reduced and cleaved in the reducing milieu of the cytoplasm, thus potentially improving DNA release and consequently transfection. The DNA--disulphide-lipid complexation was monitored by ethidium bromide exclusion, and the size of complexes was determined by dynamic light scattering. It was found that the reduction kinetics of disulphide groups in DNA--lipid complexes depended on the position of the disulphide linker within the lipid molecule. Furthermore, the internal structure of DNA--lipid particles was examined by small-angle X-ray scattering before and after lipid reduction. DNA release from lipid complexes was observed after the reduction of disulphide bonds of several lipids. Cell-transfection experiments suggested that complexes formed with selected reducible lipids resulted in up to 1000-fold higher reporter-gene activity, when compared with their analogues without disulphide bonds. In conclusion, reduction-sensitive groups introduced into cationic lipid backbones potentially allow enhanced DNA release from DNA--lipid complexes after intracellular reduction and represent a tool for improved vectorization. PMID:11389682

Cooperative water network system to reduce carbon footprint.

Science.gov (United States)

Lim, Seong-Rin; Park, Jong Moon

2008-08-15

Much effort has been made in reducing the carbon footprint to mitigate climate change. However, water network synthesis has been focused on reducing the consumption and cost of freshwater within each industrial plant. The objective of this study is to illustrate the necessity of the cooperation of industrial plants to reduce the total carbon footprint of their water supply systems. A mathematical optimization model to minimize global warming potentials is developed to synthesize (1) a cooperative water network system (WNS) integrated over two plants and (2) an individual WNS consisting of two WNSs separated for each plant. The cooperative WNS is compared to the individual WNS. The cooperation reduces their carbon footprint and is economically feasible and profitable. A strategy for implementing the cooperation is suggested for the fair distribution of costs and benefits. As a consequence, industrial plants should cooperate with their neighbor plants to further reduce the carbon footprint.

A filter apparatus for actively reducing noise

NARCIS (Netherlands)

Berkhoff, Arthur P.; Nijsse, G.

2006-01-01

A filter apparatus for reducing noise from a primary noise source, comprising a secondary source signal connector for generating secondary noise to reduce said primary noise and a sensor connector for connecting to a sensor for measuring said primary and secondary noise as an error signal. A first

Biased lineups: sequential presentation reduces the problem.

Science.gov (United States)

Lindsay, R C; Lea, J A; Nosworthy, G J; Fulford, J A; Hector, J; LeVan, V; Seabrook, C

1991-12-01

Biased lineups have been shown to increase significantly false, but not correct, identification rates (Lindsay, Wallbridge, & Drennan, 1987; Lindsay & Wells, 1980; Malpass & Devine, 1981). Lindsay and Wells (1985) found that sequential lineup presentation reduced false identification rates, presumably by reducing reliance on relative judgment processes. Five staged-crime experiments were conducted to examine the effect of lineup biases and sequential presentation on eyewitness recognition accuracy. Sequential lineup presentation significantly reduced false identification rates from fair lineups as well as from lineups biased with regard to foil similarity, instructions, or witness attire, and from lineups biased in all of these ways. The results support recommendations that police present lineups sequentially.

Hierarchical Traces for Reduced NSM Memory Requirements

Science.gov (United States)

Dahl, Torbjørn S.

This paper presents work on using hierarchical long term memory to reduce the memory requirements of nearest sequence memory (NSM) learning, a previously published, instance-based reinforcement learning algorithm. A hierarchical memory representation reduces the memory requirements by allowing traces to share common sub-sequences. We present moderated mechanisms for estimating discounted future rewards and for dealing with hidden state using hierarchical memory. We also present an experimental analysis of how the sub-sequence length affects the memory compression achieved and show that the reduced memory requirements do not effect the speed of learning. Finally, we analyse and discuss the persistence of the sub-sequences independent of specific trace instances.

Rationale and Design of the Reduce Elevated Left Atrial Pressure in Patients With Heart Failure (Reduce LAP-HF) Trial

DEFF Research Database (Denmark)

Hasenfuss, Gerd; Gustafsson, Finn; Kaye, David

2015-01-01

OBJECTIVE: Heart failure with preserved ejection fraction (HFpEF) is characterized by elevated left atrial pressure during rest and/or exercise. The Reduce LAP-HF (Reduce Elevated Left Atrial Pressure in Patients With Heart Failure) trial will evaluate the safety and performance of the Interatrial...... Shunt Device (IASD) System II, designed to directly reduce elevated left atrial pressure, in patients with HFpEF. METHODS: The Reduce LAP-HF Trial is a prospective, nonrandomized, open-label trial to evaluate a novel device that creates a small permanent shunt at the level of the atria. A minimum of 60...... patients with ejection fraction ≥40% and New York Heart Association functional class III or IV heart failure with a pulmonary capillary wedge pressure (PCWP) ≥15 mm Hg at rest or ≥25 mm Hg during supine bike exercise will be implanted with an IASD System II, and followed for 6 months to assess the primary...

Reduced turning frequency and delayed poultry manure addition reduces N loss from sugarcane compost

DEFF Research Database (Denmark)

Bryndum, Sofie; Muschler, R.; Nigatu, Abebe Nigussie

2017-01-01

Composting is an effective method to recycle biodegradable waste as soil amendment in smallholder farming systems. Although all essential plant nutrients are found in compost, a substantial amount of nitrogen is lost during composting. This study therefore investigated the potential of reducing N...... losses by (i) delaying the addition of nitrogen-rich substrates (i.e. poultry manure), and (ii) reducing the turning frequency during composting. Furthermore, we tested the effect of compost application method on nitrogen mineralization. Sugarcane-waste was composted for 54days with addition of poultry...... manure at the beginning (i.e. early addition) or after 21days of composting (delayed addition). The compost pile was then turned either every three or nine days. Composts were subsequently applied to soil as (i) homogeneously mixed, or (ii) stratified, and incubated for 28days to test the effect...

Correlated Electrons in Reduced Dimensions

Energy Technology Data Exchange (ETDEWEB)

Bonesteel, Nicholas E [Florida State Univ., Tallahassee, FL (United States)

2015-01-31

This report summarizes the work accomplished under the support of US DOE grant # DE-FG02-97ER45639, "Correlated Electrons in Reduced Dimensions." The underlying hypothesis of the research supported by this grant has been that studying the unique behavior of correlated electrons in reduced dimensions can lead to new ways of understanding how matter can order and how it can potentially be used. The systems under study have included i) fractional quantum Hall matter, which is realized when electrons are confined to two-dimensions and placed in a strong magnetic field at low temperature, ii) one-dimensional chains of spins and exotic quasiparticle excitations of topologically ordered matter, and iii) electrons confined in effectively ``zero-dimensional" semiconductor quantum dots.

Reducing Peripheral Inflammation with Infliximab Reduces Neuroinflammation and Improves Cognition in Rats with Hepatic Encephalopathy

Science.gov (United States)

Dadsetan, Sherry; Balzano, Tiziano; Forteza, Jerónimo; Cabrera-Pastor, Andrea; Taoro-Gonzalez, Lucas; Hernandez-Rabaza, Vicente; Gil-Perotín, Sara; Cubas-Núñez, Laura; García-Verdugo, José-Manuel; Agusti, Ana; Llansola, Marta; Felipo, Vicente

2016-01-01

Inflammation contributes to cognitive impairment in patients with hepatic encephalopathy (HE). However, the process by which peripheral inflammation results in cognitive impairment remains unclear. In animal models, neuroinflammation and altered neurotransmission mediate cognitive impairment. Taking into account these data, we hypothesized that in rats with HE: (1) peripheral inflammation is a main contributor to neuroinflammation; (2) neuroinflammation in hippocampus impairs spatial learning by altering AMPA and/or NMDA receptors membrane expression; (3) reducing peripheral inflammation with infliximab (anti-TNF-a) would improve spatial learning; (4) this would be associated with reduced neuroinflammation and normalization of the membrane expression of glutamate receptors. The aims of this work were to assess these hypotheses. We analyzed in rats with portacaval shunt (PCS) and control rats, treated or not with infliximab: (a) peripheral inflammation by measuring prostaglandin E2, IL10, IL-17, and IL-6; (b) neuroinflammation in hippocampus by analyzing microglial activation and the content of TNF-a and IL-1b; (c) AMPA and NMDA receptors membrane expression in hippocampus; and (d) spatial learning in the Radial and Morris water mazes. We assessed the effects of treatment with infliximab on peripheral inflammation, on neuroinflammation and AMPA and NMDA receptors membrane expression in hippocampus and on spatial learning and memory. PCS rats show increased serum prostaglandin E2, IL-17, and IL-6 and reduced IL-10 levels, indicating increased peripheral inflammation. PCS rats also show microglial activation and increased nuclear NF-kB and expression of TNF-a and IL-1b in hippocampus. This was associated with altered AMPA and NMDA receptors membrane expression in hippocampus and impaired spatial learning and memory in the radial and Morris water maze. Treatment with infliximab reduces peripheral inflammation in PCS rats, normalizing prostaglandin E2, IL-17, IL-6, and

Sorting, Searching, and Simulation in the MapReduce Framework

DEFF Research Database (Denmark)

Goodrich, Michael T.; Sitchinava, Nodari; Zhang, Qin

2011-01-01

usefulness of our approach by designing and analyzing efficient MapReduce algorithms for fundamental sorting, searching, and simulation problems. This study is motivated by a goal of ultimately putting the MapReduce framework on an equal theoretical footing with the well-known PRAM and BSP parallel...... in parallel computational geometry for the MapReduce framework, which result in efficient MapReduce algorithms for sorting, 2- and 3-dimensional convex hulls, and fixed-dimensional linear programming. For the case when mappers and reducers have a memory/message-I/O size of M = (N), for a small constant > 0...

Reducing Resistance

DEFF Research Database (Denmark)

Lindell, Johanna

care may influence decisions on antibiotic use. Based on video-and audio recordings of physician-patient consultations it is investigated how treatment recommendations are presented, can be changed, are forecast and explained, and finally, how they seemingly meet resistance and how this resistance......Antibiotic resistance is a growing public health problem both nationally and internationally, and efficient strategies are needed to reduce unnecessary use. This dissertation presents four research studies, which examine how communication between general practitioners and patients in Danish primary...... is responded to.The first study in the dissertation suggests that treatment recommendations on antibiotics are often done in a way that encourages patient acceptance. In extension of this, the second study of the dissertation examines a case, where acceptance of such a recommendation is changed into a shared...

Understanding Uranium Behavior in a Reduced Aquifer

Science.gov (United States)

Janot, N.; Lezama-Pacheco, J. S.; Williams, K. H.; Bernier-Latmani, R.; Long, P. E.; Davis, J. A.; Fox, P. M.; Yang, L.; Giammar, D.; Cerrato, J. M.; Bargar, J.

2012-12-01

Uranium contamination of groundwater is a concern at several US Department of Energy sites, such Old Rifle, CO. Uranium transport in the environment is mainly controlled by its oxidation state, since oxidized U(VI) is relatively mobile, whereas U(IV) is relatively insoluble. Bio-remediation of contaminated aquifers aims at immobilizing uranium in a reduced form. Previous laboratory and field studies have shown that adding electron donor (lactate, acetate, ethanol) to groundwater stimulates the activity of metal- and sulfate-reducing bacteria, which promotes U(VI) reduction in contaminated aquifers. However, obtaining information on chemical and physical forms of U, Fe and S species for sediments biostimulated in the field, as well as kinetic parameters such as U(VI) reduction rate, is challenging due to the low concentration of uranium in the aquifers (typically bio-remediation experiment at the Old Rifle site, CO, from early iron-reducing conditions to the transition to sulfate-reducing conditions. Several in-well chromatographic columns packed with sediment were deployed and were sampled at different days after the start of bio-reduction. X-ray absorption spectroscopy and X-ray microscopy were used to obtain information on Fe, S and U speciation and distribution. Chemical extractions of the reduced sediments have also been performed, to determine the rate of Fe(II) and U(IV) accumulation.

Metabolic interactions in methanogenic and sulfate-reducing bioreactors.

Science.gov (United States)

Stams, A J M; Plugge, C M; de Bok, F A M; van Houten, B H G W; Lens, P; Dijkman, H; Weijma, J

2005-01-01

In environments where the amount of electron acceptors is insufficient for complete breakdown of organic matter, methane is formed as the major reduced end product. In such methanogenic environments organic acids are degraded by syntrophic consortia of acetogenic bacteria and methanogenic archaea. Hydrogen consumption by methanogens is essential for acetogenic bacteria to convert organic acids to acetate and hydrogen. Several syntrophic cocultures growing on propionate and butyrate have been described. These syntrophic fatty acid-degrading consortia are affected by the presence of sulfate. When sulfate is present sulfate-reducing bacteria compete with methanogenic archaea for hydrogen and acetate, and with acetogenic bacteria for propionate and butyrate. Sulfate-reducing bacteria easily outcompete methanogens for hydrogen, but the presence of acetate as carbon source may influence the outcome of the competition. By contrast, acetoclastic methanogens can compete reasonably well with acetate-degrading sulfate reducers. Sulfate-reducing bacteria grow much faster on propionate and butyrate than syntrophic consortia.

iHadoop: Asynchronous Iterations Support for MapReduce

KAUST Repository

Elnikety, Eslam

2011-08-01

MapReduce is a distributed programming framework designed to ease the development of scalable data-intensive applications for large clusters of commodity machines. Most machine learning and data mining applications involve iterative computations over large datasets, such as the Web hyperlink structures and social network graphs. Yet, the MapReduce model does not efficiently support this important class of applications. The architecture of MapReduce, most critically its dataflow techniques and task scheduling, is completely unaware of the nature of iterative applications; tasks are scheduled according to a policy that optimizes the execution for a single iteration which wastes bandwidth, I/O, and CPU cycles when compared with an optimal execution for a consecutive set of iterations. This work presents iHadoop, a modified MapReduce model, and an associated implementation, optimized for iterative computations. The iHadoop model schedules iterations asynchronously. It connects the output of one iteration to the next, allowing both to process their data concurrently. iHadoop\\'s task scheduler exploits inter- iteration data locality by scheduling tasks that exhibit a producer/consumer relation on the same physical machine allowing a fast local data transfer. For those iterative applications that require satisfying certain criteria before termination, iHadoop runs the check concurrently during the execution of the subsequent iteration to further reduce the application\\'s latency. This thesis also describes our implementation of the iHadoop model, and evaluates its performance against Hadoop, the widely used open source implementation of MapReduce. Experiments using different data analysis applications over real-world and synthetic datasets show that iHadoop performs better than Hadoop for iterative algorithms, reducing execution time of iterative applications by 25% on average. Furthermore, integrating iHadoop with HaLoop, a variant Hadoop implementation that caches

Reducing Excellence Gaps: A Research-Based Model

Science.gov (United States)

Plucker, Jonathan A.; Peters, Scott J.; Schmalensee, Stephanie

2017-01-01

As the awareness of the existence and negative effects of excellence gaps has grown among educators and policy makers, so too has a desire for research-supported interventions to reduce these gaps. A recent review of research related to promoting equitable outcomes for all gifted students identified six specific strategies for reducing excellence…

Reduced TCA Flux in Diabetic Myotubes

DEFF Research Database (Denmark)

Gaster, Michael

2012-01-01

The diabetic phenotype is complex, requiring elucidation of key initiating defects. Diabetic myotubes express a primary reduced tricarboxylic acid (TCA) cycle flux but at present it is unclear in which part of the TCA cycle the defect is localised. In order to localise the defect we studied ATP p...... production of investigated substrate combinations was significantly reduced in mitochondria isolated from type 2 diabetic subjects compared to lean. However, when ATP synthesis rates at different substrate combinations were normalized to the corresponding individual pyruvate-malate rate...

Two-phase alkali-metal experiments in reduced gravity

International Nuclear Information System (INIS)

Antoniak, Z.I.

1986-06-01

Future space missions envision the use of large nuclear reactors utilizing either a single or a two-phase alkali-metal working fluid. The design and analysis of such reactors require state-of-the-art computer codes that can properly treat alkali-metal flow and heat transfer in a reduced-gravity environment. A literature search of relevant experiments in reduced gravity is reported on here, and reveals a paucity of data for such correlations. The few ongoing experiments in reduced gravity are noted. General plans are put forth for the reduced-gravity experiments which will have to be performed, at NASA facilities, with benign fluids. A similar situation exists regarding two-phase alkali-metal flow and heat transfer, even in normal gravity. Existing data are conflicting and indequate for the task of modeling a space reactor using a two-phase alkali-metal coolant. The major features of past experiments are described here. Data from the reduced-gravity experiments with innocuous fluids are to be combined with normal gravity data from the two-phase alkali-metal experiments. Analyses undertaken here give every expectation that the correlations developed from this data base will provide a valid representation of alkali-metal heat transfer and pressure drop in reduced gravity

Reducing dust and allergen exposure in bakeries

Directory of Open Access Journals (Sweden)

Howard J Mason

2017-12-01

Full Text Available Bakers have a continuing high incidence of occupational allergic asthma. In factory bakeries they are exposed not only to flour dust containing allergens, but also improvers whose ingredients enhance the strength and workability of the dough and its speed of rising. Improvers are flour-based but can contain added soya, fungal or bacterial enzymes that are also allergenic, as well as vegetable oil, calcium sulphate/silicate and organic esters. This study investigated the dustiness of the components used in factory bakeries and whether altering improver ingredients could reduce dust and allergen exposure. A standardised rotating drum test was employed on the individual components, as well as a representative improver and three practicable improver modifications by decreasing calcium sulphate, calcium silicate or increasing oil content. Levels of dust, the allergens wheat flour amylase inhibitor (WAAI and soya trypsin inhibitor (STI were measured in the generated inhalable, thoracic and respirable sized fractions. A “scooping and pouring” workplace simulation was also performed. Initial tests showed that dustiness of several wheat flours was relatively low, and even lower for soya flour, but increased in combination with some other improver components. All three improver modifications generally reduced levels of dust, STI and WAAI, but increasing oil content significantly decreased dust and STI in comparison to the standard improver and those improvers with reduced calcium silicate or sulphate. The simulation demonstrated that increased oil content reduced inhalable levels of gravimetric dust, STI and WAAI. Changing improver formulation, such as increasing oil content of flour by a small amount, may represent a simple, practical method of reducing bakery workers’ exposure to dust and allergens where improvers are used. It may be a useful adjunct to engineering control, changes to work practices and appropriate training in reducing the risk to

REST-MapReduce: An Integrated Interface but Differentiated Service

Directory of Open Access Journals (Sweden)

Jong-Hyuk Park

2014-01-01

Full Text Available With the fast deployment of cloud computing, MapReduce architectures are becoming the major technologies for mobile cloud computing. The concept of MapReduce was first introduced as a novel programming model and implementation for a large set of computing devices. In this research, we propose a novel concept of REST-MapReduce, enabling users to use only the REST interface without using the MapReduce architecture. This approach provides a higher level of abstraction by integration of the two types of access interface, REST API and MapReduce. The motivation of this research stems from the slower response time for accessing simple RDBMS on Hadoop than direct access to RDMBS. This is because there is overhead to job scheduling, initiating, starting, tracking, and management during MapReduce-based parallel execution. Therefore, we provide a good performance for REST Open API service and for MapReduce, respectively. This is very useful for constructing REST Open API services on Hadoop hosting services, for example, Amazon AWS (Macdonald, 2005 or IBM Smart Cloud. For evaluating performance of our REST-MapReduce framework, we conducted experiments with Jersey REST web server and Hadoop. Experimental result shows that our approach outperforms conventional approaches.

Estimating Reduced Consumption for Dynamic Demand Response

Energy Technology Data Exchange (ETDEWEB)

Chelmis, Charalampos [Univ. of Southern California, Los Angeles, CA (United States); Aman, Saima [Univ. of Southern California, Los Angeles, CA (United States); Saeed, Muhammad Rizwan [Univ. of Southern California, Los Angeles, CA (United States); Frincu, Marc [Univ. of Southern California, Los Angeles, CA (United States); Prasanna, Viktor K. [Univ. of Southern California, Los Angeles, CA (United States)

2015-01-30

Growing demand is straining our existing electricity generation facilities and requires active participation of the utility and the consumers to achieve energy sustainability. One of the most effective and widely used ways to achieve this goal in the smart grid is demand response (DR), whereby consumers reduce their electricity consumption in response to a request sent from the utility whenever it anticipates a peak in demand. To successfully plan and implement demand response, the utility requires reliable estimate of reduced consumption during DR. This also helps in optimal selection of consumers and curtailment strategies during DR. While much work has been done on predicting normal consumption, reduced consumption prediction is an open problem that is under-studied. In this paper, we introduce and formalize the problem of reduced consumption prediction, and discuss the challenges associated with it. We also describe computational methods that use historical DR data as well as pre-DR conditions to make such predictions. Our experiments are conducted in the real-world setting of a university campus microgrid, and our preliminary results set the foundation for more detailed modeling.

Solid oxide fuel cell cathode with oxygen-reducing layer

Science.gov (United States)

Surdoval, Wayne A.; Berry, David A.; Shultz, Travis

2018-04-03

The disclosure provides a SOFC comprised of an electrolyte, anode, and cathode, where the cathode comprises an MIEC and an oxygen-reducing layer. The oxygen-reducing layer is in contact with the MIEC, and the MIEC is generally between and separating the oxygen-reducing layer and the electrolyte. The oxygen-reducing layer is comprised of single element oxides, single element carbonates, or mixtures thereof, and has a thickness of less than about 30 nm. In a particular embodiment, the thickness is less than 5 nm. In another embodiment, the thickness is about 3 monolayers or less. The oxygen-reducing layer may be a continuous film or a discontinuous film with various coverage ratios. The oxygen-reducing layer at the thicknesses described may be generated on the MIEC surface using means known in the art such as, for example, ALD processes.

Reducing Outdoor Advertising

Directory of Open Access Journals (Sweden)

Patrice de Rendinger

2006-05-01

Full Text Available The fundamental concept is that public space is not a private property. So, a facade (the outer skin, the last millimeter belongs to the town, not to the owner of the building. Changing the rendering, a window, adding or removing anything from a facade requires a permission delivered by the town's authority.In places like Paris, Bordeaux, Marseilles, Lyon, Strasbourg… everywhere one can find a registrated building such as a cathedral, a castle, or a group of ancient buildings, a national administration is controlling this permission. This administration is called «historical monuments administration» and is locally lead by a specialized architect.In the late seventies, French government decided to reduce advertising on the roads and on the city walls. Advertising on the road was leading to a confusion reducing the efficacy of the roadsigns and direction signs, which is dangerous. The reduction was under control of a national administration: the ministry of equipment in charge of the roads design. Advertising on the walls with publicity boards was under control of the cities. Every city has a townplanning regulation. Many cities included forbidding advertisement boards on the walls in this regulation.A couple of firms, but mainly once (Decaux found clever to give a hand to the cities to control advertising. Decaux developed a line of bus stop shelters including advertisements and advertising panels and paid the cities the right to put rather smaller publicities on the public domain.Now Decaux is no more alone on this market and the cities are comparing offers.Marseille turned to a foreign advertising firm who pays three times the price Decaux paid… for half of the advertising surface. Freiburg erased totally the public domain advertisements, selling the tramways and bus coachwork as advertising spaces. Paris is reopening the advertising market before the end of Deacaux's contract and will pay Deacaux a huge amount

Moral elevation reduces prejudice against gay men.

Science.gov (United States)

Lai, Calvin K; Haidt, Jonathan; Nosek, Brian A

2014-01-01

Disgust is linked to social evaluation. People with higher disgust sensitivity exhibit more sexual prejudice, and inducing disgust increases sexual prejudice. We tested whether inducing moral elevation, the theoretical opposite of disgust, would reduce sexual prejudice. In four studies (N = 3622), we induced elevation with inspiring videos and then measured sexual prejudice with implicit and explicit measures. Compared to control videos that elicited no particular affective state, we found that elevation reduced implicit and explicit sexual prejudice, albeit very slightly. No effect was observed when the target of social evaluation was changed to race (Black-White). Inducing amusement, another positive emotion, did not significantly affect sexual prejudice. We conclude that elevation weakly but reliably reduces prejudice towards gay men.

MARIANE: MApReduce Implementation Adapted for HPC Environments

Energy Technology Data Exchange (ETDEWEB)

Fadika, Zacharia; Dede, Elif; Govindaraju, Madhusudhan; Ramakrishnan, Lavanya

2011-07-06

MapReduce is increasingly becoming a popular framework, and a potent programming model. The most popular open source implementation of MapReduce, Hadoop, is based on the Hadoop Distributed File System (HDFS). However, as HDFS is not POSIX compliant, it cannot be fully leveraged by applications running on a majority of existing HPC environments such as Teragrid and NERSC. These HPC environments typicallysupport globally shared file systems such as NFS and GPFS. On such resourceful HPC infrastructures, the use of Hadoop not only creates compatibility issues, but also affects overall performance due to the added overhead of the HDFS. This paper not only presents a MapReduce implementation directly suitable for HPC environments, but also exposes the design choices for better performance gains in those settings. By leveraging inherent distributed file systems' functions, and abstracting them away from its MapReduce framework, MARIANE (MApReduce Implementation Adapted for HPC Environments) not only allows for the use of the model in an expanding number of HPCenvironments, but also allows for better performance in such settings. This paper shows the applicability and high performance of the MapReduce paradigm through MARIANE, an implementation designed for clustered and shared-disk file systems and as such not dedicated to a specific MapReduce solution. The paper identifies the components and trade-offs necessary for this model, and quantifies the performance gains exhibited by our approach in distributed environments over Apache Hadoop in a data intensive setting, on the Magellan testbed at the National Energy Research Scientific Computing Center (NERSC).

Nonperturbative treatment of reduced model with fermions

International Nuclear Information System (INIS)

Gutierrez, W.R.

1983-01-01

A nonperturbative method is presented to show that the reduced model produces the correct leading large-N contribution to the fermion Green's functions. A new form of the reduced model is introduced, which avoids the quenching procedure. Also the equation for the meson bound states is discussed. The method is illustrated in the case of two-dimensional QCD

Detecting reduced renal function in children

DEFF Research Database (Denmark)

Andersen, Trine Borup; Jødal, Lars; Erlandsen, Erland J

2013-01-01

Background The aim of this study was to compare the ability of renal indicators [serum creatinine (SCr), cystatin C (SCysC)] and glomerular filtration rate (GFR)-models to discriminate normal and reduced renal function. As a single cut-off level will always lead to false classifications, we propose...... function was defined as a GFR ofcreatinine (SCr-ratio), and eight published GFR-models were compared for their ability to correctly classify renal function as normal or reduced. Cut-off levels were determined so as to give 99 % certainty outside the gray zone...

Symmetry of semi-reduced lattices.

Science.gov (United States)

Stróż, Kazimierz

2015-05-01

The main result of this work is extension of the famous characterization of Bravais lattices according to their metrical, algebraic and geometric properties onto a wide class of primitive lattices (including Buerger-reduced, nearly Buerger-reduced and a substantial part of Delaunay-reduced) related to low-restricted semi-reduced descriptions (s.r.d.'s). While the `geometric' operations in Bravais lattices map the basis vectors into themselves, the `arithmetic' operators in s.r.d. transform the basis vectors into cell vectors (basis vectors, face or space diagonals) and are represented by matrices from the set {\\bb V} of all 960 matrices with the determinant ±1 and elements {0, ±1} of the matrix powers. A lattice is in s.r.d. if the moduli of off-diagonal elements in both the metric tensors M and M(-1) are smaller than corresponding diagonal elements sharing the same column or row. Such lattices are split into 379 s.r.d. types relative to the arithmetic holohedries. Metrical criteria for each type do not need to be explicitly given but may be modelled as linear derivatives {\\bb M}(p,q,r), where {\\bb M} denotes the set of 39 highest-symmetry metric tensors, and p,q,r describe changes of appropriate interplanar distances. A sole filtering of {\\bb V} according to an experimental s.r.d. metric and subsequent geometric interpretation of the filtered matrices lead to mathematically stable and rich information on the Bravais-lattice symmetry and deviations from the exact symmetry. The emphasis on the crystallographic features of lattices was obtained by shifting the focus (i) from analysis of a lattice metric to analysis of symmetry matrices [Himes & Mighell (1987). Acta Cryst. A43, 375-384], (ii) from the isometric approach and invariant subspaces to the orthogonality concept {some ideas in Le Page [J. Appl. Cryst. (1982), 15, 255-259]} and splitting indices [Stróż (2011). Acta Cryst. A67, 421-429] and (iii) from fixed cell transformations to transformations

Breastfeeding reduces postpartum weight retention

DEFF Research Database (Denmark)

Baker, Jennifer Lyn; Gamborg, Michael; Heitmann, Berit L

2008-01-01

BACKGROUND: Weight gained during pregnancy and not lost postpartum may contribute to obesity in women of childbearing age. OBJECTIVE: We aimed to determine whether breastfeeding reduces postpartum weight retention (PPWR) in a population among which full breastfeeding is common and breastfeeding...... duration is long. DESIGN: We selected women from the Danish National Birth Cohort who ever breastfed (>98%), and we conducted the interviews at 6 (n = 36 030) and 18 (n = 26 846) mo postpartum. We used regression analyses to investigate whether breastfeeding (scored to account for duration and intensity......) reduced PPWR at 6 and 18 mo after adjustment for maternal prepregnancy body mass index (BMI) and gestational weight gain (GWG). RESULTS: GWG was positively (P postpartum. Breastfeeding was negatively associated with PPWR in all women but those...

The research on reactivity of alternative carbon reducers

OpenAIRE

Łabaj, J.; Słowikowski, M.; Żymła, W.; Lipart, J.

2013-01-01

The research involved measuring of the speed of zinc oxide with carbon reducers. Samples weighing between 60 and 100 mg were tested with the use of thermogravimetric analysis within the range of temperatures up to 1 100 °C in nitrogen atmosphere. The speed of heating was 20 deg min-1. The research involved also reducers normally used in reduction processes. The results obtained prove that some of the alternative reducers may be used for industrial purposes.

Neural Mechanisms of Updating under Reducible and Irreducible Uncertainty.

Science.gov (United States)

Kobayashi, Kenji; Hsu, Ming

2017-07-19

Adaptive decision making depends on an agent's ability to use environmental signals to reduce uncertainty. However, because of multiple types of uncertainty, agents must take into account not only the extent to which signals violate prior expectations but also whether uncertainty can be reduced in the first place. Here we studied how human brains of both sexes respond to signals under conditions of reducible and irreducible uncertainty. We show behaviorally that subjects' value updating was sensitive to the reducibility of uncertainty, and could be quantitatively characterized by a Bayesian model where agents ignore expectancy violations that do not update beliefs or values. Using fMRI, we found that neural processes underlying belief and value updating were separable from responses to expectancy violation, and that reducibility of uncertainty in value modulated connections from belief-updating regions to value-updating regions. Together, these results provide insights into how agents use knowledge about uncertainty to make better decisions while ignoring mere expectancy violation. SIGNIFICANCE STATEMENT To make good decisions, a person must observe the environment carefully, and use these observations to reduce uncertainty about consequences of actions. Importantly, uncertainty should not be reduced purely based on how surprising the observations are, particularly because in some cases uncertainty is not reducible. Here we show that the human brain indeed reduces uncertainty adaptively by taking into account the nature of uncertainty and ignoring mere surprise. Behaviorally, we show that human subjects reduce uncertainty in a quasioptimal Bayesian manner. Using fMRI, we characterize brain regions that may be involved in uncertainty reduction, as well as the network they constitute, and dissociate them from brain regions that respond to mere surprise. Copyright © 2017 the authors 0270-6474/17/376972-11$15.00/0.

Primaquine for reducing Plasmodium falciparum transmission.

Science.gov (United States)

Graves, Patricia M; Gelband, Hellen; Garner, Paul

2012-09-12

Mosquitoes become infected with malaria when they ingest gametocyte stages of the parasite from the blood of a human host. Plasmodium falciparum gametocytes are sensitive to the drug primaquine (PQ). The World Health Organization (WHO) recommends giving a single dose or short course of PQ alongside primary treatment for people ill with P. falciparum infection to reduce malaria transmission. Gametocytes themselves cause no symptoms, so this intervention does not directly benefit individuals. PQ causes haemolysis in some people with glucose-6-phosphate dehydrogenase (G6PD) deficiency so may not be safe.   To assess whether a single dose or short course of PQ added to treatments for malaria caused by P. falciparum infection reduces malaria transmission and is safe. We searched the following databases up to 10 April 2012 for studies: the Cochrane Infectious Diseases Group Specialized Register; the Cochrane Central Register of Controlled Trials (CENTRAL), published in The Cochrane Library; MEDLINE; EMBASE; LILACS; metaRegister of Controlled Trials (mRCT) and the WHO trials search portal using 'malaria*', 'falciparum', and 'primaquine' as search terms. In addition, we searched conference proceedings and reference lists of included studies, and we contacted likely researchers and organizations for relevant trials. Trials of mass treatment of whole populations (or actively detected fever or malaria cases within such populations) with antimalarial drugs, compared to treatment with the same drug plus PQ; or patients with clinical malaria being treated for malaria at health facilities randomized to short course/single dose PQ versus no PQ. Two authors (PMG and HG) independently screened all abstracts, applied inclusion criteria, and abstracted data. We sought data on the effect of PQ on malaria transmission intensity, participant infectiousness, the number of participants with gametocytes, and gametocyte density over time. We stratified results by primary treatment drug as

How inhibiting nitrification affects nitrogen cycle and reduces ...

Science.gov (United States)

We conducted a meta-analysis of 103 nitrification inhibitor (NI) studies, and evaluated how NI application affects crop productivity and other ecosystem services in agricultural systems. Our results showed that, compared to conventional fertilizer practice, applications of NI along with nitrogen (N) fertilizer increased crop nitrogen use efficiency, crop yield, and altered the pathways and the amount of N loss to environment. NI application increased ammonia emission, but reduced nitrate leaching and nitrous oxide emission, which led to a reduction of 12.9% of the total N loss. The cost and benefit analysis showed that the economic benefit of reducing N’s environmental impacts offset the cost of NI. NI application could bring additional revenue of $163.72 ha-1 for a maize farm. Taken together, our findings show that NI application may create a win-win scenario that increases agricultural output, while reducing the negative impact on the environment. Policies that encourage NI application would reduce N’s environmental impacts. A group from Chinese Academy of Sciences, US EPA-ORD and North Carolina examined the net environmental and economic effects of nitrification inhibitors to reduce nitrate leaching associated with farm fertilizers. They conducted a meta-analysis of studies examining nitrification inhibitors, and found that NI application increased ammonia emission, but reduced nitrate leaching and nitrous oxide emission, which led to a reduction of 12.9

Biochemical characterization of cholesterol-reducing Eubacterium.

Science.gov (United States)

Mott, G E; Brinkley, A W; Mersinger, C L

1980-12-01

We characterized two isolates of cholesterol-reducing Eubacterium by conducting conventional biochemical tests and by testing various sterols and glycerolipids as potential growth factors. In media containing cholesterol and plasmenylethanolamine, the tests for nitrate reduction, indole production, and gelatin and starch hydrolyses were negative, and no acid was produced from any of 22 carbohydrates. Both isolates hydrolyzed esculin to esculetin, indicating beta-glycosidase activity. In addition to plasmenylethanolamine, five other lipids which contain an alkenyl ether residue supported growth of Eubacterium strain 403 in a lecithin-cholesterol base medium. Of six steroids tested, cholesterol, cholest-4-en-3-one, cholest-4-en-3 beta-ol (allocholesterol), and androst-5-en-3 beta-ol-17-one supported growth of Eubacterium strain 403. All four steroids were reduced to the 3 beta-ol, 5 beta-H products. The delta 5 steroids cholest-5-en-3 alpha-ol (epicholesterol) and 22,23-bisnor-5-cholenic acid-3-beta-ol were not reduced and did not support growth of the Eubacterium strain.

Reducing consumption of electric current and energy carriers. [USSR

Energy Technology Data Exchange (ETDEWEB)

Ruppo, A.S.; Gruzdev, Yu.M.

1985-01-01

Evaluates the energy conservation program developed by the Giproshakht research institute is evaluated. The program was used in the Afanas'evo hydraulic mine in the Tulaugol association (with annual coal output of 2.1 Mt). Energy conservation program consisted of 2 groups of tasks: reducing energy consumption of the mine, and reducing energy consumption during the maximum demand hours in the morning and evening. The following methods were used: reducing idle running of chain and belt conveyors, separate draining of mine water free of dust and rock particles (reducing range of water cleaning), use of automatic control systems for mine blowers, automatic control of the system for coal drying, more efficient use of coal and materials transport in the mine. Energy demand of the mine during peak demand hours was reduced by adjusting fluctuations of energy consumption of the mine to fluctuations of energy demand in the power system of the area, e.g. by reducing mine draining in the morning and evening and operating at full capacity during the time of reduced energy demand. Using the energy conservation measures economized 4,324,300 kWh electric energy annually.

Does Improvised Waterbed Reduce the Incidence of Pressure ...

African Journals Online (AJOL)

Does Improvised Waterbed Reduce the Incidence of Pressure Ulcers in Patients with Spinal Injury? ... The use of bed replacements markedly reduces the incidence of pressure ... Keywords: Neurological deficits, plastic sachet, table water ...

Sludge displacement verification for reducing grout report

International Nuclear Information System (INIS)

Caldwell, T.B.; Langton, C.A.

1997-01-01

To support the closure of HLW tanks at SRS, a reducing grout was developed that is formulated to reduce the mobility of radionuclides left in each tank. During non-radioactive flow tests of the grout, it was discovered that, in addition to its desired properties, the grout has the ability to move residual waste a considerable distance across the tank floor

Reduced-Rank Adaptive Filtering Using Krylov Subspace

Directory of Open Access Journals (Sweden)

Sergueï Burykh

2003-01-01

Full Text Available A unified view of several recently introduced reduced-rank adaptive filters is presented. As all considered methods use Krylov subspace for rank reduction, the approach taken in this work is inspired from Krylov subspace methods for iterative solutions of linear systems. The alternative interpretation so obtained is used to study the properties of each considered technique and to relate one reduced-rank method to another as well as to algorithms used in computational linear algebra. Practical issues are discussed and low-complexity versions are also included in our study. It is believed that the insight developed in this paper can be further used to improve existing reduced-rank methods according to known results in the domain of Krylov subspace methods.

Integrable semi-discretizations of the reduced Ostrovsky equation

International Nuclear Information System (INIS)

Feng, Bao-Feng; Maruno, Ken-ichi; Ohta, Yasuhiro

2015-01-01

Based on our previous work on the reduced Ostrovsky equation (J. Phys. A: Math. Theor. 45 355203), we construct its integrable semi-discretizations. Since the reduced Ostrovsky equation admits two alternative representations, one being its original form, the other the differentiated form (the short wave limit of the Degasperis–Procesi equation) two semi-discrete analogues of the reduced Ostrovsky equation are constructed possessing the same N-loop soliton solution. The relationship between these two versions of semi-discretizations is also clarified. (paper)

The research on reactivity of alternative carbon reducers

Directory of Open Access Journals (Sweden)

J. Lipart

2013-01-01

Full Text Available The research involved measuring of the speed of zinc oxide with carbon reducers. Samples weighing between 60 and 100 mg were tested with the use of thermogravimetric analysis within the range of temperatures up to 1 100 °C in nitrogen atmosphere. The speed of heating was 20 deg min-1. The research involved also reducers normally used in reduction processes. The results obtained prove that some of the alternative reducers may be used for industrial purposes.

Thermophilic Sulfate-Reducing Bacteria in Cold Marine Sediment

DEFF Research Database (Denmark)

ISAKSEN, MF; BAK, F.; JØRGENSEN, BB

1994-01-01

sulfate-reducing bacteria was detected. Time course experiments showed constant sulfate reduction rates at 4 degrees C and 30 degrees C, whereas the activity at 60 degrees C increased exponentially after a lag period of one day. Thermophilic, endospore-forming sulfate-reducing bacteria, designated strain...... C to search for presence of psychrophilic, mesophilic and thermophilic sulfate-reducing bacteria. Detectable activity was initially only in the mesophilic range, but after a lag phase sulfate reduction by thermophilic sulfate-reducing bacteria were observed. No distinct activity of psychrophilic...... P60, were isolated and characterized as Desulfotomaculum kuznetsovii. The temperature response of growth and respiration of strain P60 agreed well with the measured sulfate reduction at 50 degrees-70 degrees C. Bacteria similar to strain P60 could thus be responsible for the measured thermophilic...

Thermophilic Sulfate-Reducing Bacteria in Cold Marine Sediment

DEFF Research Database (Denmark)

ISAKSEN, MF; BAK, F.; JØRGENSEN, BB

1994-01-01

C to search for presence of psychrophilic, mesophilic and thermophilic sulfate-reducing bacteria. Detectable activity was initially only in the mesophilic range, but after a lag phase sulfate reduction by thermophilic sulfate-reducing bacteria were observed. No distinct activity of psychrophilic...... sulfate-reducing bacteria was detected. Time course experiments showed constant sulfate reduction rates at 4 degrees C and 30 degrees C, whereas the activity at 60 degrees C increased exponentially after a lag period of one day. Thermophilic, endospore-forming sulfate-reducing bacteria, designated strain...... P60, were isolated and characterized as Desulfotomaculum kuznetsovii. The temperature response of growth and respiration of strain P60 agreed well with the measured sulfate reduction at 50 degrees-70 degrees C. Bacteria similar to strain P60 could thus be responsible for the measured thermophilic...

Lighting system with a device for reducing system wattage

NARCIS (Netherlands)

1996-01-01

A lighting system having a high pressure gas discharge lamp intended to be operated on a stabilization ballast further includes a low loss device to reduce the current through the ballast and lamp, thereby reducing system wattage for energy savings. For a lead-type ballast, the current reducing

BCJ numerators from reduced Pfaffian

Energy Technology Data Exchange (ETDEWEB)

Du, Yi-Jian [Center for Theoretical Physics, School of Physics and Technology, Wuhan University,No. 299 Bayi Road, Wuhan 430072 (China); Teng, Fei [Department of Physics and Astronomy, University of Utah,115 South 1400 East, Salt Lake City, UT 84112 (United States)

2017-04-07

By expanding the reduced Pfaffian in the tree level Cachazo-He-Yuan (CHY) integrands for Yang-Mills (YM) and nonlinear sigma model (NLSM), we can get the Bern-Carrasco-Johansson (BCJ) numerators in Del Duca-Dixon-Maltoni (DDM) form for arbitrary number of particles in any spacetime dimensions. In this work, we give a set of very straightforward graphic rules based on spanning trees for a direct evaluation of the BCJ numerators for YM and NLSM. Such rules can be derived from the Laplace expansion of the corresponding reduced Pfaffian. For YM, the each one of the (n−2)! DDM form BCJ numerators contains exactly (n−1)! terms, corresponding to the increasing trees with respect to the color order. For NLSM, the number of nonzero numerators is at most (n−2)!−(n−3)!, less than those of several previous constructions.

Reduced central blood volume in cirrhosis

DEFF Research Database (Denmark)

Bendtsen, F; Henriksen, Jens Henrik Sahl; Sørensen, T I

1989-01-01

than 0.0001). The lowest values (18 ml/kg) were found in patients with gross ascites and a reduced systemic vascular resistance. In patients with cirrhosis central blood volume was inversely correlated to the hepatic venous pressure gradient (r = -0.41, p less than 0.01), and the total blood volume...... was inversely correlated to the systemic vascular resistance (r = -0.49, p less than 0.001), the latter being significantly reduced in the patient group. Patients with cirrhosis apparently are unable to maintain a normal central blood volume. This may be due to arteriolar vasodilation, portosystemic collateral...

Novel Reduced-Feedback Wireless Communication Systems

KAUST Repository

Shaqfeh, Mohammad Obaidah; Alnuweiri, Hussein; Alouini, Mohamed-Slim

2011-01-01

We have recently contributed to this field and published several journal and conference papers. We are the pioneers to propose a novel reduced-feedback opportunistic scheduling scheme that combines many desired features including fairness in resources distribution across the active terminals and distributed processing at the MAC layer level. In addition our scheme operates close to the upper capacity limits of achievable transmission rates over wireless links. We have also proposed another hybrid scheme that enables adjusting the feedback load flexibly based on rates requirements. We are currently investigating other novel ideas to design reduced-feedback communication systems.

Reducing hypothetical bias in choice experiments

DEFF Research Database (Denmark)

Ladenburg, Jacob; Olsen, Søren Bøye; Nielsen, Rasmus Christian Fejer

eliminate some of the hypothetical bias. The present paper tests an addition to Cheap Talk, an Opt-Out Reminder. The Opt-Out Reminder is an objective short script presented prior to the choice sets, prompting the respondent to choose the opt-out alternative, if he/she finds the proposed policy generated...... alternatives in a choice set too expensive. The results suggest that adding an Opt-Out Reminder to Cheap Talk can in fact reduce hypothetical bias even further and reduces some of the ineffectiveness of CT in relation to the survey bid range and experienced respondents....

SURFACE PROPERTIES OF ELECTROCHEMICALLY REDUCED ...

African Journals Online (AJOL)

DJFLEX

A viscose rayon based activated carbon cloth (ACC) was electrochemically reduced ..... bath of liquid nitrogen at a temperature of 77 K. ... that above 59,400 c/g extent of oxidation, the ..... ACC react with aldehyde groups to produce ether.

Bioremediation: Effectiveness in reducing the ecological impact

International Nuclear Information System (INIS)

Scholten, M.C.T.

1992-01-01

Bioremediation becomes an important technique in oil spill combat programmes. The purpose is to shorten the exposure time of biota to oil compounds, in order to reduce long term environmental effects. Although bioremediation products have the advantage of stimulating the natural capacity to degrade oil, there are some limitations to be considered. Application as a technique for first emergency actions following an oil spill is not effective, and can therefore be no alternative for dispersion or mechanical removal of floating or freshly stranded oil slicks. Acute toxic effects are related to the short term exposure to unweathered oils. An immediate removal of oil is necessary to reduce the extent of the environmental impact of an oil spill. Physical processes (transport, dilution and evaporation) are determining the initial fate of environmentally released oil. Biodegradation only becomes important as a process of removing oil in the next phase. It is the only effective way to further reduce the concentration of oil that is left in (intertidal) coastal areas. Bioremediation thus reduces the duration of the environmental impact of an oil spill. This is especially important in ecosystems with a low recovery potential (e.g., salt marshes, rocky shores). The experimental evaluation of bioremediation products is mainly based on the capacity to reduce fresh oil and the acute toxicity of the product itself, rather than on the capacity to enhance the further reduction of weathered oil and the toxicological consequences of higher release rates of intermediate metabolites produced during the biotransformation processes

7 CFR 226.23 - Free and reduced-price meals.

Science.gov (United States)

2010-01-01

... to revise its free and reduced-price policy statement or its nondiscrimination statement unless the... shall develop a policy statement for determining eligibility for free and reduced-price meals which... 7 Agriculture 4 2010-01-01 2010-01-01 false Free and reduced-price meals. 226.23 Section 226.23...

M3: Matrix Multiplication on MapReduce

DEFF Research Database (Denmark)

Silvestri, Francesco; Ceccarello, Matteo

2015-01-01

M3 is an Hadoop library for performing dense and sparse matrix multiplication in MapReduce. The library is based on multi-round algorithms exploiting the 3D decomposition of the problem.......M3 is an Hadoop library for performing dense and sparse matrix multiplication in MapReduce. The library is based on multi-round algorithms exploiting the 3D decomposition of the problem....

UK: Welsh court reduces sentence, cites HIV status.

Science.gov (United States)

Marceau, Emmanuelle

2003-08-01

A Welsh appeal court has reduced the sentence handed down to an offender because of his HIV status, despite his lengthy criminal record. The court reduced the sentence from five to three-and-a-half years' imprisonment.

Nature of Reduced Carbon in Martian Meteorites

Science.gov (United States)

Gibson, Everett K., Jr.; McKay, D. S.; Thomas-Keprta, K. L.; Clemett, S. J.; White, L. M.

2012-01-01

Martian meteorites provide important information on the nature of reduced carbon components present on Mars throughout its history. The first in situ analyses for carbon on the surface of Mars by the Viking landers yielded disappointing results. With the recognition of Martian meteorites on Earth, investigations have shown carbon-bearing phases exist on Mars. Studies have yielded presence of reduced carbon, carbonates and inferred graphitic carbon phases. Samples ranging in age from the first approximately 4 Ga of Mars history [e.g. ALH84001] to nakhlites with a crystallization age of 1.3 Ga [e.g. Nakhla] with aqueous alteration processes occurring 0.5-0.7 Ga after crystallizaton. Shergottites demonstrate formation ages around 165-500 Ma with younger aqueous alterations events. Only a limited number of the Martian meteorites do not show evidence of significance terrestrial alterations. Selected areas within ALH84001, Nakhla, Yamato 000593 and possibly Tissint are suitable for study of their indigenous reduced carbon bearing phases. Nakhla possesses discrete, well-defined carbonaceous phases present within iddingsite alteration zones. Based upon both isotopic measurements and analysis of Nakhla's organic phases the presence of pre-terrestrial organics is now recognized. The reduced carbon-bearing phases appear to have been deposited during preterrestrial aqueous alteration events that produced clays. In addition, the microcrystalline layers of Nakhla's iddingsite have discrete units of salt crystals suggestive of evaporation processes. While we can only speculate on the origin of these unique carbonaceous structures, we note that the significance of such observations is that it may allow us to understand the role of Martian carbon as seen in the Martian meteorites with obvious implications for astrobiology and the pre-biotic evolution of Mars. In any case, our observations strongly suggest that reduced organic carbon exists as micrometer- size, discrete structures

Impact of mutations on the midpoint potential of the [4Fe-4S]+1,+2 cluster and on catalytic activity in electron transfer flavoprotein-ubiquinone oxidoreductase (ETF-QO).

Science.gov (United States)

Usselman, Robert J; Fielding, Alistair J; Frerman, Frank E; Watmough, Nicholas J; Eaton, Gareth R; Eaton, Sandra S

2008-01-08

Electron-transfer flavoprotein-ubiquinone oxidoreductase (ETF-QO) is an iron-sulfur flavoprotein that accepts electrons from electron-transfer flavoprotein (ETF) and reduces ubiquinone from the Q-pool. ETF-QO contains a single [4Fe-4S]2+,1+ cluster and one equivalent of FAD, which are diamagnetic in the isolated oxidized enzyme and can be reduced to paramagnetic forms by enzymatic donors or dithionite. Mutations were introduced by site-directed mutagenesis of amino acids in the vicinity of the iron-sulfur cluster of Rhodobacter sphaeroides ETF-QO. Y501 and T525 are equivalent to Y533 and T558 in the porcine ETF-QO. In the porcine protein, these residues are within hydrogen-bonding distance of the Sgamma of the cysteine ligands to the iron-sulfur cluster. Y501F, T525A, and Y501F/T525A substitutions were made to determine the effects on midpoint potential, activity, and EPR spectral properties of the cluster. The integrity of the mutated proteins was confirmed by optical spectra, EPR g-values, and spin-lattice relaxation rates, and the cluster to flavin point-dipole distance was determined by relaxation enhancement. Potentiometric titrations were monitored by changes in the CW EPR signals of the cluster and semiquinone. Single mutations decreased the midpoint potentials of the iron-sulfur cluster from +37 mV for wild type to -60 mV for Y501F and T525A and to -128 mV for Y501F/T525A. Lowering the midpoint potential resulted in a decrease in steady-state ubiquinone reductase activity and in ETF semiquinone disproportionation. The decrease in activity demonstrates that reduction of the iron-sulfur cluster is required for activity. There was no detectable effect of the mutations on the flavin midpoint potentials.

Impact of Mutations on the Midpoint Potential of the [4Fe-4S]+1,+2 Cluster and on Catalytic Activity in Electron Transfer Flavoprotein-ubiquinone Oxidoreductase (ETF-QO)†

Science.gov (United States)

Usselman, Robert J.; Fielding, Alistair J.; Frerman, Frank E.; Watmough, Nicholas J.; Eaton, Gareth R.; Eaton, Sandra S.

2011-01-01

Electron transfer flavoprotein - ubiquinone oxidoreductase (ETF-QO) is an iron-sulfur flavoprotein that accepts electrons from electron-transfer flavoprotein (ETF) and reduces ubiquinone from the Q-pool. ETF-QO contains a single [4Fe-4S]2+,1+ cluster and one equivalent of FAD, which are diamagnetic in the isolated oxidized enzyme and can be reduced to paramagnetic forms by enzymatic donors or dithionite. Mutations were introduced by site-directed mutagenesis of amino acids in the vicinity of the iron-sulfur cluster of Rhodobacter sphaeroides ETF-QO. Y501 and T525 are equivalent to Y533 and T558 in the porcine ETF-QO. In the porcine protein, these residues are within hydrogen bonding distance of the Sγ of the cysteine ligands to the iron-sulfur cluster. Y501F, T525A, and Y501F/T525A substitutions were made to determine the effects on midpoint potential, activity, and EPR spectral properties of the cluster. The integrity of the mutated proteins was confirmed by optical spectra, EPR g-values, and spin-lattice relaxation rates, and the cluster to flavin point-dipole distance was determined by relaxation enhancement. Potentiometric titrations were monitored by changes in the CW EPR signals of the cluster and semiquinone. Single mutations decreased the mid-point potentials of the iron-sulfur cluster from +37 mV for wild type to −60 mV for Y501F and T525A and to −128 mV for Y501F/T525A. Lowering the midpoint potential resulted in a decrease in steady-state ubiquinone reductase activity and in ETF semiquinone disproportionation. The decrease in activity demonstrates that reduction of the iron-sulfur cluster is required for activity. There was no detectable effect of the mutations on the flavin midpoint potentials. PMID:18069858

The evolution of glutathione metabolism in phototrophic microorganisms

Science.gov (United States)

Fahey, R. C.; Buschbacher, R. M.; Newton, G. L.

1987-01-01

Of the many roles ascribed to glutathione (GSH) the one most clearly established is its role in the protection of higher eucaryotes against oxygen toxicity through destruction of thiol-reactive oxygen byproducts. If this is the primary function of GSH then GSH metabolism should have evolved during or after the evolution of oxygenic photosynthesis. That many bacteria do not produce GSH is consistent with this view. In the present study we have examined the low-molecular-weight thiol composition of a variety of phototrophic microorganisms to ascertain how evolution of GSH production is related to evolution of oxygenic photosynthesis. Cells were extracted in the presence of monobromobimane (mBBr) to convert thiols to fluorescent derivatives, which were analyzed by high-pressure liquid chromatography. Significant levels of GSH were not found in the green bacteria (Chlorobium thiosulfatophilum and Chloroflexus aurantiacus). Substantial levels of GSH were present in the purple bacteria (Chromatium vinosum, Rhodospirillum rubrum, Rhodobacter sphaeroides, and Rhodocyclus gelatinosa), the cyanobacteria [Anacystis nidulans, Microcoleus chthonoplastes S.G., Nostoc muscorum, Oscillatoria amphigranulata, Oscillatoria limnetica, Oscillatoria sp. (Stinky Spring, Utah), Oscillatoria terebriformis, Plectonema boryanum, and Synechococcus lividus], and eucaryotic algae (Chlorella pyrenoidsa, Chlorella vulgaris, Euglena gracilis, Scenedesmus obliquus, and Chlamydomonas reinhardtii). Other thiols measured included cysteine, gamma-glutamylcysteine, thiosulfate, coenzyme A, and sulfide; several unidentified thiols were also detected. Many of the organisms examined also exhibited a marked ability to reduce mBBr to syn-(methyl,methyl)bimane, an ability that was quenched by treatment with 2-pyridyl disulfide or 5,5'-bisdithio-(2-nitrobenzoic acid) prior to reaction with mBBr. These observations indicate the presence of a reducing system capable of electron transfer to mBBr and reduction of

Reducing the Burden of Price.

Science.gov (United States)

Hansen, Janet S.

1984-01-01

Setting prices for undergraduate education and assessing their effects on consumers and institutions is complicated by widespread price discounting. Student aid programs, credit, subsidized employment, and tax policy can reduce the actual costs paid by students and their families. (MSE)

Ways to reduce miner absenteeism

Energy Technology Data Exchange (ETDEWEB)

1989-11-01

Discussion is presented of the use of attendance programs at mines, to reduce interruptions to production, decrease labour costs, and to improve safety. Techniques described include use of absentee charts, frequency of attendance charts, and rewards for good attendance. 3 figs.

A reduced adjoint approach to variational data assimilation

KAUST Repository

Altaf, Muhammad

2013-02-01

The adjoint method has been used very often for variational data assimilation. The computational cost to run the adjoint model often exceeds several original model runs and the method needs significant programming efforts to implement the adjoint model code. The work proposed here is variational data assimilation based on proper orthogonal decomposition (POD) which avoids the implementation of the adjoint of the tangent linear approximation of the original nonlinear model. An ensemble of the forward model simulations is used to determine the approximation of the covariance matrix and only the dominant eigenvectors of this matrix are used to define a model subspace. The adjoint of the tangent linear model is replaced by the reduced adjoint based on this reduced space. Thus the adjoint model is run in reduced space with negligible computational cost. Once the gradient is obtained in reduced space it is projected back in full space and the minimization process is carried in full space. In the paper the reduced adjoint approach to variational data assimilation is introduced. The characteristics and performance of the method are illustrated with a number of data assimilation experiments in a ground water subsurface contaminant model. © 2012 Elsevier B.V.

A reduced adjoint approach to variational data assimilation

KAUST Repository

Altaf, Muhammad; El Gharamti, Mohamad; Heemink, Arnold W.; Hoteit, Ibrahim

2013-01-01

The adjoint method has been used very often for variational data assimilation. The computational cost to run the adjoint model often exceeds several original model runs and the method needs significant programming efforts to implement the adjoint model code. The work proposed here is variational data assimilation based on proper orthogonal decomposition (POD) which avoids the implementation of the adjoint of the tangent linear approximation of the original nonlinear model. An ensemble of the forward model simulations is used to determine the approximation of the covariance matrix and only the dominant eigenvectors of this matrix are used to define a model subspace. The adjoint of the tangent linear model is replaced by the reduced adjoint based on this reduced space. Thus the adjoint model is run in reduced space with negligible computational cost. Once the gradient is obtained in reduced space it is projected back in full space and the minimization process is carried in full space. In the paper the reduced adjoint approach to variational data assimilation is introduced. The characteristics and performance of the method are illustrated with a number of data assimilation experiments in a ground water subsurface contaminant model. © 2012 Elsevier B.V.

Considering dominance in reduced single-step genomic evaluations.

Science.gov (United States)

Ertl, J; Edel, C; Pimentel, E C G; Emmerling, R; Götz, K-U

2018-06-01

Single-step models including dominance can be an enormous computational task and can even be prohibitive for practical application. In this study, we try to answer the question whether a reduced single-step model is able to estimate breeding values of bulls and breeding values, dominance deviations and total genetic values of cows with acceptable quality. Genetic values and phenotypes were simulated (500 repetitions) for a small Fleckvieh pedigree consisting of 371 bulls (180 thereof genotyped) and 553 cows (40 thereof genotyped). This pedigree was virtually extended for 2,407 non-genotyped daughters. Genetic values were estimated with the single-step model and with different reduced single-step models. Including more relatives of genotyped cows in the reduced single-step model resulted in a better agreement of results with the single-step model. Accuracies of genetic values were largest with single-step and smallest with reduced single-step when only the cows genotyped were modelled. The results indicate that a reduced single-step model is suitable to estimate breeding values of bulls and breeding values, dominance deviations and total genetic values of cows with acceptable quality. © 2018 Blackwell Verlag GmbH.

Reducing longitudinal emittance growth in RFQ accelerators

International Nuclear Information System (INIS)

Koscielniak, S.

1994-08-01

Bunching and capture of a monochromatic beam into an rf bucket inevitably lead to substantial emittance growth through the mechanisms of filamentation and non-adiabatic variation of parameters. We describe a three step strategy for minimizing this growth, based on a clear understanding of the non-linear beam dynamics, and apply to acceleration of heavy ions with Z/A = 1/60 (and initial kinetic energy 60 keV/u) in a radio frequency quadrupole (RFQ) operating at 25 MHz. We also describe a scheme, to further reduce the emittance, based upon the use of an external RFQ-type prebuncher before the main accelerator. The external unit permits the bunching voltage to be reduced, to inject into a moving bucket, and to reduce the structure length. (author). 7 refs., 6 figs

Corn Cultivation to Reduce the Mycotoxin Contamination

Directory of Open Access Journals (Sweden)

Yangseon Kim

2017-09-01

Full Text Available The effects of insecticide and fungicide treatment were investigated to reduce mycotoxin contamination of corn (Zea mays L. seeds. Deoxynivalenol and zearalenone contents were reduced in the treated seeds, but aflatoxin, ochratoxin A, fumonisin, and T-2 toxin were not effective by chemical treatments. The chemical treatment did not affect the growth of saprophyte, but inhibited the pathogenic fungi such as Fusarium verticillioides, F. graminearum and F. equiseti. Myotoxin contents at different harvesting time were compared. As the harvest time was delayed, both levels of deoxynivalenol and zearalenone and frequency of Fusarium spp. increased. However, the major nutrient contents of corn seeds were not affected by harvesting period. These results show that chemical treatments are necessary to reduce the fungal contamination of corn and harvest without delay is important as well.

Study on IR Properties of Reduced Graphene Oxide

Science.gov (United States)

Ma, Deyue; Li, Xiaoxia; Guo, Yuxiang; Zeng, Yurun

2018-01-01

Firstly, the reduced graphene oxide was prepared by modified hummer method and characterized. Then, the complex refractive index of reduced graphene oxide in IR band was tested and its IR absorption and radiation properties were researched by correlated calculation. The results show that reduced graphene oxide prepared by hummer method are multilayered graphene with defects and functional groups on its surface. Its absorption in near and far IR bands is strong, but it’s weaker in middle IR band. At the IR atmosphere Window, its normal spectral emissivity decreases with wavelength increasing, and its total normal spectral emissivity in 3 ∼ 5μm and 8 ∼ 14μm are 0.75 and 0.625, respectively. Therefore, reduced graphene oxide can be used as IR absorption and coating materials and have a great potential in microwave and infrared compatible materials.

12-step programs to reduce illicit drug use

DEFF Research Database (Denmark)

Filges, Trine; Nielsen, Sine Kirkegaard; Jørgensen, Anne-Marie Klint

2014-01-01

Many treatments are not rigorously evaluated as to their effectiveness, and it is uncertain which types of interventions are more effective than others in reducing illicit drug use. The aim of this paper is to provide a systematic mapping of the research literature of the effectiveness of 12-step...... programs in reducing illicit drug use. A systematic literature search was conducted based on 17 international and Nordic Bibliographic databases. A total of 15993 references were screened, and eleven unique studies were finally included in this mapping. The included studies demonstrated conflicting results...... regarding the effectiveness of the 12-step treatment and TSF in reducing individuals’ drug use. Two studies reported a positive effect of the TSF treatment compared to the comparison conditions in reducing drug use. Six studies reported no differences between 12-step program and the comparison condition...

Human Performance in Simulated Reduced Gravity Environments

Science.gov (United States)

Cowley, Matthew; Harvill, Lauren; Rajulu, Sudhakar

2014-01-01

NASA is currently designing a new space suit capable of working in deep space and on Mars. Designing a suit is very difficult and often requires trade-offs between performance, cost, mass, and system complexity. Our current understanding of human performance in reduced gravity in a planetary environment (the moon or Mars) is limited to lunar observations, studies from the Apollo program, and recent suit tests conducted at JSC using reduced gravity simulators. This study will look at our most recent reduced gravity simulations performed on the new Active Response Gravity Offload System (ARGOS) compared to the C-9 reduced gravity plane. Methods: Subjects ambulated in reduced gravity analogs to obtain a baseline for human performance. Subjects were tested in lunar gravity (1.6 m/sq s) and Earth gravity (9.8 m/sq s) in shirt-sleeves. Subjects ambulated over ground at prescribed speeds on the ARGOS, but ambulated at a self-selected speed on the C-9 due to time limitations. Subjects on the ARGOS were given over 3 minutes to acclimate to the different conditions before data was collected. Nine healthy subjects were tested in the ARGOS (6 males, 3 females, 79.5 +/- 15.7 kg), while six subjects were tested on the C-9 (6 males, 78.8 +/- 11.2 kg). Data was collected with an optical motion capture system (Vicon, Oxford, UK) and was analyzed using customized analysis scripts in BodyBuilder (Vicon, Oxford, UK) and MATLAB (MathWorks, Natick, MA, USA). Results: In all offloaded conditions, variation between subjects increased compared to 1-g. Kinematics in the ARGOS at lunar gravity resembled earth gravity ambulation more closely than the C-9 ambulation. Toe-off occurred 10% earlier in both reduced gravity environments compared to earth gravity, shortening the stance phase. Likewise, ankle, knee, and hip angles remained consistently flexed and had reduced peaks compared to earth gravity. Ground reaction forces in lunar gravity (normalized to Earth body weight) were 0.4 +/- 0.2 on

Oxytocin reduces amygdala activity, increases social interactions, and reduces anxiety-like behavior irrespective of NMDAR antagonism.

Science.gov (United States)

Sobota, Rosanna; Mihara, Takuma; Forrest, Alexandra; Featherstone, Robert E; Siegel, Steven J

2015-08-01

Standard dopamine therapies for schizophrenia are not efficacious for negative symptoms of the disease, including asociality. This reduced social behavior may be due to glutamatergic dysfunction within the amygdala, leading to increased fear and social anxiety. Several studies have demonstrated the prosocial effects of oxytocin in schizophrenia patients. Therefore, this study evaluates the effect of subchronic oxytocin on EEG activity in amygdala of mice during performance of the three-chamber social choice and open field tests following acute ketamine as a model of glutamatergic dysfunction. Oxytocin did not restore social deficits introduced by ketamine but did significantly increase sociality in comparison to the control group. Ketamine had no effect on time spent in the center during the open field trials, whereas oxytocin increased overall center time across all groups, suggesting a reduction in anxiety. Amygdala activity was consistent across all drug groups during social and nonsocial behavioral trials. However, oxytocin reduced overall amygdala EEG power during the two behavioral tasks. Alternatively, ketamine did not significantly affect EEG power throughout the tasks. Decreased EEG power in the amygdala, as caused by oxytocin, may be related to both reduced anxiety and increased social behaviors. Data suggest that separate prosocial and social anxiety pathways may mediate social preference. (c) 2015 APA, all rights reserved).

On nonlinear reduced order modeling

International Nuclear Information System (INIS)

Abdel-Khalik, Hany S.

2011-01-01

When applied to a model that receives n input parameters and predicts m output responses, a reduced order model estimates the variations in the m outputs of the original model resulting from variations in its n inputs. While direct execution of the forward model could provide these variations, reduced order modeling plays an indispensable role for most real-world complex models. This follows because the solutions of complex models are expensive in terms of required computational overhead, thus rendering their repeated execution computationally infeasible. To overcome this problem, reduced order modeling determines a relationship (often referred to as a surrogate model) between the input and output variations that is much cheaper to evaluate than the original model. While it is desirable to seek highly accurate surrogates, the computational overhead becomes quickly intractable especially for high dimensional model, n ≫ 10. In this manuscript, we demonstrate a novel reduced order modeling method for building a surrogate model that employs only 'local first-order' derivatives and a new tensor-free expansion to efficiently identify all the important features of the original model to reach a predetermined level of accuracy. This is achieved via a hybrid approach in which local first-order derivatives (i.e., gradient) of a pseudo response (a pseudo response represents a random linear combination of original model’s responses) are randomly sampled utilizing a tensor-free expansion around some reference point, with the resulting gradient information aggregated in a subspace (denoted by the active subspace) of dimension much less than the dimension of the input parameters space. The active subspace is then sampled employing the state-of-the-art techniques for global sampling methods. The proposed method hybridizes the use of global sampling methods for uncertainty quantification and local variational methods for sensitivity analysis. In a similar manner to

Evaluating Active Interventions to Reduce Student Procrastination

OpenAIRE

Martin, Joshua Deckert

2015-01-01

Procrastination is a pervasive problem in education. In computer science, procrastination and lack of necessary time management skills to complete programming projects are viewed as primary causes of student attrition. The most effective techniques known to reduce procrastination are resource-intensive and do not scale well to large classrooms. In this thesis, we examine three course interventions designed to both reduce procrastination and be scalable for large classrooms. Reflective writ...

Acid-reducing vagotomy is associated with reduced risk of subsequent ischemic heart disease in complicated peptic ulcer: An Asian population study.

Science.gov (United States)

Wu, Shih-Chi; Fang, Chu-Wen; Chen, William Tzu-Liang; Muo, Chih-Hsin

2016-12-01

Persistent exacerbation of a peptic ulcer may lead to a complicated peptic ulcer (perforation or/and bleeding). The management of complicated peptic ulcers has shifted from acid-reducing vagotomy, drainage, and gastrectomy to simple local suture or non-operative (endoscopic/angiographic) hemostasis. We were interested in the long-term effects of this trend change. In this study, complicated peptic ulcer patients who received acid-reducing vagotomy were compared with those who received simple suture/hemostasis to determine the risk of ischemic heart disease (IHD).This retrospective cohort study analyzed 335,680 peptic ulcer patients recorded from 2000 to 2006 versus 335,680 age-, sex-, comorbidity-, and index-year matched comparisons. Patients with Helicobacter pylori (HP) infection were excluded. In order to identify the effect of vagus nerve severance, patients who received gastrectomy or antrectomy were also excluded. The incidence of IHD in both cohorts, and in the complicated peptic ulcer patients who received acid-reducing vagotomy versus those who received simple suture or hemostasis was evaluated.The overall incidence of IHD was higher in patients with peptic ulcer than those without peptic ulcer (17.00 vs 12.06 per 1000 person-years), with an adjusted hazard ratio (aHR) of 1.46 based on multivariable Cox proportional hazards regression analysis controlling for age, sex, Charlson's comorbidity index, and death (competing risk). While comparing peptic ulcer patients with acid-reducing vagotomy to those with simple suture/hemostasis or those without surgical treatment, the aHR (0.58) was the lowest in the acid-reducing vagotomy group.Patients with peptic ulcer have an elevated risk of IHD. However, complicated peptic ulcer patients who received acid-reducing vagotomy were associated with reduced risk of developing IHD.

Alcohol reduces aversion to ambiguity

Directory of Open Access Journals (Sweden)

Tadeusz eTyszka

2015-01-01

Full Text Available Several years ago, Cohen, Dearnaley, and Hansel [1] demonstrated that under the influence of alcohol drivers became more risk prone, although their risk perception remained unchanged. Research shows that ambiguity aversion is to some extent positively correlated with risk aversion, though not very highly [2]. The question addressed by the present research is whether alcohol reduces ambiguity aversion. Our research was conducted in a natural setting (a restaurant bar, where customers with differing levels of alcohol intoxication were offered a choice between a risky and an ambiguous lottery. We found that alcohol reduced ambiguity aversion and that the effect occurred in men but not women. We interpret these findings in terms of the risk-as-value hypothesis, according to which, people in Western culture tend to value risk, and suggest that alcohol consumption triggers adherence to socially and culturally valued patterns of conduct different for men and women.

Alcohol reduces aversion to ambiguity.

Science.gov (United States)

Tyszka, Tadeusz; Macko, Anna; Stańczak, Maciej

2014-01-01

Several years ago, Cohen et al. (1958) demonstrated that under the influence of alcohol drivers became more risk prone, although their risk perception remained unchanged. Research shows that ambiguity aversion is to some extent positively correlated with risk aversion, though not very highly (Camerer and Weber, 1992). The question addressed by the present research is whether alcohol reduces ambiguity aversion. Our research was conducted in a natural setting (a restaurant bar), where customers with differing levels of alcohol intoxication were offered a choice between a risky and an ambiguous lottery. We found that alcohol reduced ambiguity aversion and that the effect occurred in men but not women. We interpret these findings in terms of the risk-as-value hypothesis, according to which, people in Western culture tend to value risk, and suggest that alcohol consumption triggers adherence to socially and culturally valued patterns of conduct different for men and women.

Reducing carbon dioxide to products

Science.gov (United States)

Cole, Emily Barton; Sivasankar, Narayanappa; Parajuli, Rishi; Keets, Kate A

2014-09-30

A method reducing carbon dioxide to one or more products may include steps (A) to (C). Step (A) may bubble said carbon dioxide into a solution of an electrolyte and a catalyst in a divided electrochemical cell. The divided electrochemical cell may include an anode in a first cell compartment and a cathode in a second cell compartment. The cathode may reduce said carbon dioxide into said products. Step (B) may adjust one or more of (a) a cathode material, (b) a surface morphology of said cathode, (c) said electrolyte, (d) a manner in which said carbon dioxide is bubbled, (e), a pH level of said solution, and (f) an electrical potential of said divided electrochemical cell, to vary at least one of (i) which of said products is produced and (ii) a faradaic yield of said products. Step (C) may separate said products from said solution.

Endotoxemia reduces cerebral perfusion but enhances dynamic cerebrovascular autoregulation at reduced arterial carbon dioxide tension*

DEFF Research Database (Denmark)

Brassard, Patrice; Kim, Yu-Sok; van Lieshout, Johannes

2012-01-01

OBJECTIVE:: The administration of endotoxin to healthy humans reduces cerebral blood flow but its influence on dynamic cerebral autoregulation remains unknown. We considered that a reduction in arterial carbon dioxide tension would attenuate cerebral perfusion and improve dynamic cerebral autoreg...

Reducing Abdominal Fat Deposition in Broiler Through Feeding Management

Directory of Open Access Journals (Sweden)

Cecep Hidayat

2015-09-01

Full Text Available Abdominal fat in broiler carcass is considered as a waste and its existence reduces the carcass quality. Abdominal fat deposition is affected by several factors such as genetic, nutrition, feed, sex, age and environment. Reducing abdominal fat deposition can be carried out by regulating the nutrient intake to ensure that no excessive nutrient was consumed. Nutrition effects to reduce abdominal fat deposition are associated with nutrient concentration of ration and quantity of daily feed intake. Daily nutrient intake can be limited, especially through restricted feeding. It is concluded that an appropriate feeding management can reduce abdominal fat deposition in broiler.

Preparation of potassium-reduced tantalum powders

International Nuclear Information System (INIS)

Kolosov, V.N.; Miroshnichenko, M.N.; Orlov, V.M.; Prokhorova, T.Yu.

2005-01-01

Characteristics of tantalum powders prepared by reduction of molten potassium heptafluorotantalate with liquid potassium are studied in a temperature range of 750 - 850 deg C using potassium chloride as a flux at a ratio of K 2 TaF 7 : KCl = 1, 2, and 3. The use of potassium as a reducing agent facilitates washing of tantalum powders for impurity salt removal, reduces sodium content and leakage currents in the anodes. As compared to sodium process, the potassium reduction results in a high yield of sponge material, a decrease in the specific surface area and yield of tantalum powder suitable for manufacture of capacitor anodes [ru

Does Formal Employment Reduce Informal Caregiving?

Science.gov (United States)

He, Daifeng; McHenry, Peter

2016-07-01

Using the Survey of Income and Program Participation, we examine the impact of formal employment on informal caregiving. We instrument for individual work hours with state unemployment rates. We find that, among women of prime caregiving ages (40-64 years), working 10% more hours per week reduces the probability of providing informal care by about 2 percentage points. The effects are stronger for more time-intensive caregiving and if care recipients are household members. Our results imply that work-promoting policies have the unintended consequence of reducing informal caregiving in an aging society. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

Corona discharge ion mobility spectrometry at reduced pressures

International Nuclear Information System (INIS)

Tabrizchi, Mahmoud; Rouholahnejad, Fereshteh

2004-01-01

Ion mobility spectrometers (IMSs) normally operate at ambient pressure. In this work an IMS cell has been designed and constructed to allow the pressure to be reduced inside the IMS cell. In this cell, corona discharge was employed as the ionization source. Reducing pressure affected both the discharge and the performance of the IMS. The discharge current was observed to increase with reducing pressure while the ignition potential decreased. The ion current received at the collector plate was also increased about 50 times when the pressure was reduced from ambient pressure to 15 Torr. The higher ion current can lead to an extended dynamic range. IMS spectra were recorded at various pressures and the results show that the drift times shift perfectly linear with pressure. This suggests that unlike temperature, pressure correction for ion mobility spectra is as simple as multiplying the drift times by a factor of 760/P

Hybrid reduced order modeling for assembly calculations

Energy Technology Data Exchange (ETDEWEB)

Bang, Youngsuk, E-mail: ysbang00@fnctech.com [FNC Technology, Co. Ltd., Yongin-si (Korea, Republic of); Abdel-Khalik, Hany S., E-mail: abdelkhalik@purdue.edu [Purdue University, West Lafayette, IN (United States); Jessee, Matthew A., E-mail: jesseema@ornl.gov [Oak Ridge National Laboratory, Oak Ridge, TN (United States); Mertyurek, Ugur, E-mail: mertyurek@ornl.gov [Oak Ridge National Laboratory, Oak Ridge, TN (United States)

2015-12-15

Highlights: • Reducing computational cost in engineering calculations. • Reduced order modeling algorithm for multi-physics problem like assembly calculation. • Non-intrusive algorithm with random sampling. • Pattern recognition in the components with high sensitive and large variation. - Abstract: While the accuracy of assembly calculations has considerably improved due to the increase in computer power enabling more refined description of the phase space and use of more sophisticated numerical algorithms, the computational cost continues to increase which limits the full utilization of their effectiveness for routine engineering analysis. Reduced order modeling is a mathematical vehicle that scales down the dimensionality of large-scale numerical problems to enable their repeated executions on small computing environment, often available to end users. This is done by capturing the most dominant underlying relationships between the model's inputs and outputs. Previous works demonstrated the use of the reduced order modeling for a single physics code, such as a radiation transport calculation. This manuscript extends those works to coupled code systems as currently employed in assembly calculations. Numerical tests are conducted using realistic SCALE assembly models with resonance self-shielding, neutron transport, and nuclides transmutation/depletion models representing the components of the coupled code system.

Hybrid reduced order modeling for assembly calculations

International Nuclear Information System (INIS)

Bang, Youngsuk; Abdel-Khalik, Hany S.; Jessee, Matthew A.; Mertyurek, Ugur

2015-01-01

Highlights: • Reducing computational cost in engineering calculations. • Reduced order modeling algorithm for multi-physics problem like assembly calculation. • Non-intrusive algorithm with random sampling. • Pattern recognition in the components with high sensitive and large variation. - Abstract: While the accuracy of assembly calculations has considerably improved due to the increase in computer power enabling more refined description of the phase space and use of more sophisticated numerical algorithms, the computational cost continues to increase which limits the full utilization of their effectiveness for routine engineering analysis. Reduced order modeling is a mathematical vehicle that scales down the dimensionality of large-scale numerical problems to enable their repeated executions on small computing environment, often available to end users. This is done by capturing the most dominant underlying relationships between the model's inputs and outputs. Previous works demonstrated the use of the reduced order modeling for a single physics code, such as a radiation transport calculation. This manuscript extends those works to coupled code systems as currently employed in assembly calculations. Numerical tests are conducted using realistic SCALE assembly models with resonance self-shielding, neutron transport, and nuclides transmutation/depletion models representing the components of the coupled code system.

Interventions: Employees’ Perceptions of What Reduces Stress

Directory of Open Access Journals (Sweden)

Silvia Pignata

2017-01-01

Full Text Available Objective. To build upon research evaluating stress interventions, this qualitative study tests the framework of the extended Job Demands-Resources model to investigate employees’ perceptions of the stress-reduction measures implemented at 13 Australian universities. Methods. In a cross-sectional survey design, tenured and contract staff indicated whether their overall level of stress had changed during the previous three-four years, and, if so, they described the major causes. A total of 462 staff reported that their level of stress had decreased; the study examines commentary from 115 academic and 304 nonacademic staff who provided details of what they perceived to be effective in reducing stress. Results. Thematic analyses show that the key perceived causes were changes in job or work role, new heads of departments or supervisors, and the use of organizational strategies to reduce or manage stress. A higher percentage of academic staff reported reduced stress due to using protective coping strategies or their increased recognition and/or success, whereas a higher percentage of nonacademic staff reported reduced stress due to increases in staffing resources and/or systems. Conclusion. These results identify the importance of implementing multilevel strategies to enhance employees’ well-being. Nonacademic staff, in particular, specified a variety of organizational stress-reduction interventions.

Global Cardiovascular and Renal Outcomes of Reduced GFR.

Science.gov (United States)

Thomas, Bernadette; Matsushita, Kunihiro; Abate, Kalkidan Hassen; Al-Aly, Ziyad; Ärnlöv, Johan; Asayama, Kei; Atkins, Robert; Badawi, Alaa; Ballew, Shoshana H; Banerjee, Amitava; Barregård, Lars; Barrett-Connor, Elizabeth; Basu, Sanjay; Bello, Aminu K; Bensenor, Isabela; Bergstrom, Jaclyn; Bikbov, Boris; Blosser, Christopher; Brenner, Hermann; Carrero, Juan-Jesus; Chadban, Steve; Cirillo, Massimo; Cortinovis, Monica; Courville, Karen; Dandona, Lalit; Dandona, Rakhi; Estep, Kara; Fernandes, João; Fischer, Florian; Fox, Caroline; Gansevoort, Ron T; Gona, Philimon N; Gutierrez, Orlando M; Hamidi, Samer; Hanson, Sarah Wulf; Himmelfarb, Jonathan; Jassal, Simerjot K; Jee, Sun Ha; Jha, Vivekanand; Jimenez-Corona, Aida; Jonas, Jost B; Kengne, Andre Pascal; Khader, Yousef; Khang, Young-Ho; Kim, Yun Jin; Klein, Barbara; Klein, Ronald; Kokubo, Yoshihiro; Kolte, Dhaval; Lee, Kristine; Levey, Andrew S; Li, Yongmei; Lotufo, Paulo; El Razek, Hassan Magdy Abd; Mendoza, Walter; Metoki, Hirohito; Mok, Yejin; Muraki, Isao; Muntner, Paul M; Noda, Hiroyuki; Ohkubo, Takayoshi; Ortiz, Alberto; Perico, Norberto; Polkinghorne, Kevan; Al-Radaddi, Rajaa; Remuzzi, Giuseppe; Roth, Gregory; Rothenbacher, Dietrich; Satoh, Michihiro; Saum, Kai-Uwe; Sawhney, Monika; Schöttker, Ben; Shankar, Anoop; Shlipak, Michael; Silva, Diego Augusto Santos; Toyoshima, Hideaki; Ukwaja, Kingsley; Umesawa, Mitsumasa; Vollset, Stein Emil; Warnock, David G; Werdecker, Andrea; Yamagishi, Kazumasa; Yano, Yuichiro; Yonemoto, Naohiro; Zaki, Maysaa El Sayed; Naghavi, Mohsen; Forouzanfar, Mohammad H; Murray, Christopher J L; Coresh, Josef; Vos, Theo

2017-07-01

The burden of premature death and health loss from ESRD is well described. Less is known regarding the burden of cardiovascular disease attributable to reduced GFR. We estimated the prevalence of reduced GFR categories 3, 4, and 5 (not on RRT) for 188 countries at six time points from 1990 to 2013. Relative risks of cardiovascular outcomes by three categories of reduced GFR were calculated by pooled random effects meta-analysis. Results are presented as deaths for outcomes of cardiovascular disease and ESRD and as disability-adjusted life years for outcomes of cardiovascular disease, GFR categories 3, 4, and 5, and ESRD. In 2013, reduced GFR was associated with 4% of deaths worldwide, or 2.2 million deaths (95% uncertainty interval [95% UI], 2.0 to 2.4 million). More than half of these attributable deaths were cardiovascular deaths (1.2 million; 95% UI, 1.1 to 1.4 million), whereas 0.96 million (95% UI, 0.81 to 1.0 million) were ESRD-related deaths. Compared with metabolic risk factors, reduced GFR ranked below high systolic BP, high body mass index, and high fasting plasma glucose, and similarly with high total cholesterol as a risk factor for disability-adjusted life years in both developed and developing world regions. In conclusion, by 2013, cardiovascular deaths attributed to reduced GFR outnumbered ESRD deaths throughout the world. Studies are needed to evaluate the benefit of early detection of CKD and treatment to decrease these deaths. Copyright © 2017 by the American Society of Nephrology.

How is ozone pollution reducing our food supply?

Science.gov (United States)

Wilkinson, Sally; Mills, Gina; Illidge, Rosemary; Davies, William J

2012-01-01

Ground-level ozone pollution is already decreasing global crop yields (from ∼2.2-5.5% for maize to 3.9-15% and 8.5-14% for wheat and soybean, respectively), to differing extents depending on genotype and environmental conditions, and this problem is predicted to escalate given climate change and increasing ozone precursor emissions in many areas. Here a summary is provided of how ozone pollution affects yield in a variety of crops, thus impacting global food security. Ozone causes visible injury symptoms to foliage; it induces early senescence and abscission of leaves; it can reduce stomatal aperture and thereby carbon uptake, and/or directly reduce photosynthetic carbon fixation; it can moderate biomass growth via carbon availability or more directly; it can decrease translocation of fixed carbon to edible plant parts (grains, fruits, pods, roots) due either to reduced availability at source, redirection to synthesis of chemical protectants, or reduced transport capabilities via phloem; decreased carbon transport to roots reduces nutrient and water uptake and affects anchorage; ozone can moderate or bring forward flowering and induce pollen sterility; it induces ovule and/or grain abortion; and finally it reduces the ability of some genotypes to withstand other stresses such as drought, high vapour pressure deficit, and high photon flux density via effects on stomatal control. This latter point is emphasized here, given predictions that atmospheric conditions conducive to drought formation that also give rise to intense precursor emission events will become more severe over the coming decades.

Consumer detection and acceptability of reduced-sodium bread.

Science.gov (United States)

La Croix, Kimberly W; Fiala, Steven C; Colonna, Ann E; Durham, Catherine A; Morrissey, Michael T; Drum, Danna K; Kohn, Melvin A

2015-06-01

Bread is the largest contributor of Na to the American diet and excess Na consumption contributes to premature death and disability. We sought to determine the Na level at which consumers could detect a difference between reduced-Na bread and bread with typical Na content, and to determine if consumer sensory acceptability and purchase intent differed between reduced-Na bread and bread with typical Na content. Difference testing measured ability to detect differences in control bread and reduced-Na bread using two-alternative forced choice testing. Acceptability was measured using a nine-point hedonic scale and purchase intent was measured using a five-point purchase intent scale. Difference and acceptability testing were conducted in Portland, OR, USA in January 2013. Eighty-two consumers participated in difference testing and 109 consumers participated in acceptability testing. Consumers did not detect a difference in saltiness between the control bread and the 10 % reduced-Na bread, but did detect a difference between the control bread and bread reduced in Na content by 20 % and 30 %. Na reductions had no effect on consumer acceptability of sensory characteristics, including overall liking, appearance, aroma, flavour, sweetness, salt level and texture, or purchase intent. Reducing Na levels by up to 30 % in the sandwich bread tested did not affect consumer liking or purchase intent of the product. These results support national recommendations for small, incremental Na reductions in the food supply over time and assure bread manufacturers that sensory characteristics and consumer purchase intent of their products will be preserved after Na reductions occur.

Does Microfinance Reduce Income Inequality?

NARCIS (Netherlands)

Hermes, Niels

2014-01-01

This study addresses the question whether participation of the poor in microfinance contributes to reducing a country’s level of income inequality. Using data from 70 developing countries, we show that higher levels of microfinance participation are indeed associated with a reduction of the income

The role of preschool in reducing inequality

OpenAIRE

Waldfogel, Jane

2015-01-01

Children from disadvantaged families have lower levels of school readiness when they enter school than do children from more advantaged families. Many countries have tried to reduce this inequality through publicly provided preschool. Evidence on the potential of these programs to reduce inequality in child development is now quite strong. Long-term studies of large publicly funded programs in Europe and Latin America, and newer studies on state and local prekindergarten programs implemented ...

Statin use and reduced cancer-related mortality

DEFF Research Database (Denmark)

Nielsen, Sune F; Nordestgaard, Børge G; Bojesen, Stig E

2012-01-01

A reduction in the availability of cholesterol may limit the cellular proliferation required for cancer growth and metastasis. We tested the hypothesis that statin use begun before a cancer diagnosis is associated with reduced cancer-related mortality.......A reduction in the availability of cholesterol may limit the cellular proliferation required for cancer growth and metastasis. We tested the hypothesis that statin use begun before a cancer diagnosis is associated with reduced cancer-related mortality....

“Friday off”: Reducing Working Hours in Europe

Directory of Open Access Journals (Sweden)

Jack Rossiter

2013-04-01

Full Text Available This article explores the pros and cons for reducing working hours in Europe. To arrive to an informed judgment we review critically the theoretical and empirical literature, mostly from economics, concerning the relation between working hours on the one hand, and productivity, employment, quality of life, and the environment, on the other. We adopt a binary economics distinction between capital and labor productiveness, and are concerned with how working hours may be reduced without harming the earning capacity of workers. There are reasons to believe that reducing working hours may absorb some unemployment, especially in the short-run, even if less than what is advocated by proponents of the proposal. Further, there may well be strong benefits for the quality of peoples’ lives. Environmental benefits are likely but depend crucially on complementary policies or social conditions that will ensure that the time liberated will not be directed to resource-intensive or environmentally harmful consumption. It is questionable whether reduced working hours are sustainable in the long-term given resource limits and climate change. We conclude that while the results of reducing working hours are uncertain, this may be a risk worth taking, especially as an interim measure that may relieve unemployment while other necessary structural changes are instituted.

[Effective interventions to reduce absenteeism among hospital nurses].

Science.gov (United States)

Blanca-Gutiérrez, Joaquín Jesús; Jiménez-Díaz, María del Carmen; Escalera-Franco, Luis Felipe

2013-01-01

To select and summarize the interventions that have proved effective in reducing absenteeism among hospital nurses. A scoping review was conducted through a literature search using Medline, Web of Science, Cinahl, Embase, Lilacs, Cuiden and Cochrane Library Plus databases. Of a total of 361 articles extracted, 15 were finally selected for this review. The implementation of multifaceted support or physical training programs can produce positive results in terms of reducing absenteeism among hospital nurses. Cognitive-behavioral type interventions require studies with larger samples to provide conclusive results. Establishing more flexible working shifts may also reduce absenteeism rates, although again studies with larger samples are needed. Programs aimed at managing change developed by nurses themselves, participatory management of professional relations, the support provided by supervisors who are opposed to hierarchical leadership styles, and wage supplements that reward the lack of absence can also reduce these types of indicators. Absenteeism can be considered as a final result and a consequence of the level of job satisfaction. The effectiveness of interventions to reduce absenteeism among hospital nurses will no doubt largely depend on the ability of these interventions to increase the job satisfaction of these workers. Copyright © 2012 SESPAS. Published by Elsevier Espana. All rights reserved.

Innovative approaches to reduce animal testing : replace whenever possible, reduce through refinement and mechanistic understanding

NARCIS (Netherlands)

Ravenzwaay, van B.

2013-01-01

'Many of the in vitro toxicological studies have not been sufficiently validated to determine their applicability domain, even less have gained regulatory acceptance. Major advantage of in vitro testing today is the early identification of significant hazards in compound development and reduced and

Directed formation of micro- and nanoscale patterns of functional light-harvesting LH2 complexes.

Science.gov (United States)

Reynolds, Nicholas P; Janusz, Stefan; Escalante-Marun, Maryana; Timney, John; Ducker, Robert E; Olsen, John D; Otto, Cees; Subramaniam, Vinod; Leggett, Graham J; Hunter, C Neil

2007-11-28

The precision placement of the desired protein components on a suitable substrate is an essential prelude to any hybrid "biochip" device, but a second and equally important condition must also be met: the retention of full biological activity. Here we demonstrate the selective binding of an optically active membrane protein, the light-harvesting LH2 complex from Rhodobacter sphaeroides, to patterned self-assembled monolayers at the micron scale and the fabrication of nanometer-scale patterns of these molecules using near-field photolithographic methods. In contrast to plasma proteins, which are reversibly adsorbed on many surfaces, the LH2 complex is readily patterned simply by spatial control of surface polarity. Near-field photolithography has yielded rows of light-harvesting complexes only 98 nm wide. Retention of the native optical properties of patterned LH2 molecules was demonstrated using in situ fluorescence emission spectroscopy.

Cellulose synthases: new insights from crystallography and modeling.

Science.gov (United States)

Slabaugh, Erin; Davis, Jonathan K; Haigler, Candace H; Yingling, Yaroslava G; Zimmer, Jochen

2014-02-01

Detailed information about the structure and biochemical mechanisms of cellulose synthase (CelS) proteins remained elusive until a complex containing the catalytic subunit (BcsA) of CelS from Rhodobacter sphaeroides was crystalized. Additionally, a 3D structure of most of the cytosolic domain of a plant CelS (GhCESA1 from cotton, Gossypium hirsutum) was produced by computational modeling. This predicted structure contributes to our understanding of how plant CelS proteins may be similar and different as compared with BcsA. In this review, we highlight how these structures impact our understanding of the synthesis of cellulose and other extracellular polysaccharides. We show how the structures can be used to generate hypotheses for experiments testing mechanisms of glucan synthesis and translocation in plant CelS. Copyright © 2013 Elsevier Ltd. All rights reserved.

DOES FINANCIAL DEVELOPMENT REDUCE CORRUPTION?

OpenAIRE

John Thornton

2009-01-01

I estimate the impact of bank cred it to the private sector on corruption using indicators of a country's legal origin as instrumental variables to assess causality. I find that bank credit reduces corruption, with the result robust to instrumenting for bank credit and for different controls.

Implementation Intentions Reduce Implicit Stereotype Activation and Application.

Science.gov (United States)

Rees, Heather Rose; Rivers, Andrew Michael; Sherman, Jeffrey W

2018-05-01

Research has found that implementation intentions, if-then action plans (e.g., "if I see a Black face, I will think safe"), reduce stereotyping on implicit measures. However, it is unknown by what process(es) implementation intentions reduce implicit stereotyping. The present research examines the effects of implementation intentions on stereotype activation (e.g., extent to which stereotypic information is accessible) and stereotype application (e.g., extent to which accessible stereotypes are applied in judgment). In addition, we assessed the efficiency of implementation intentions by manipulating cognitive resources (e.g., digit-span, restricted response window) while participants made judgments on an implicit stereotyping measure. Across four studies, implementation intentions reduced implicit stereotyping. This decrease in stereotyping was associated with reductions in both stereotype activation and application. In addition, these effects of implementation intentions were highly efficient and associated with reduced stereotyping even for groups for which people may have little practice inhibiting stereotypes (e.g., gender).

Ferroelectric capacitor with reduced imprint

Science.gov (United States)

Evans, Jr., Joseph T.; Warren, William L.; Tuttle, Bruce A.; Dimos, Duane B.; Pike, Gordon E.

1997-01-01

An improved ferroelectric capacitor exhibiting reduced imprint effects in comparison to prior art capacitors. A capacitor according to the present invention includes top and bottom electrodes and a ferroelectric layer sandwiched between the top and bottom electrodes, the ferroelectric layer comprising a perovskite structure of the chemical composition ABO.sub.3 wherein the B-site comprises first and second elements and a dopant element that has an oxidation state greater than +4. The concentration of the dopant is sufficient to reduce shifts in the coercive voltage of the capacitor with time. In the preferred embodiment of the present invention, the ferroelectric element comprises Pb in the A-site, and the first and second elements are Zr and Ti, respectively. The preferred dopant is chosen from the group consisting of Niobium, Tantalum, and Tungsten. In the preferred embodiment of the present invention, the dopant occupies between 1 and 8% of the B-sites.

Reduced prefrontal connectivity in psychopathy.

Science.gov (United States)

Motzkin, Julian C; Newman, Joseph P; Kiehl, Kent A; Koenigs, Michael

2011-11-30

Linking psychopathy to a specific brain abnormality could have significant clinical, legal, and scientific implications. Theories on the neurobiological basis of the disorder typically propose dysfunction in a circuit involving ventromedial prefrontal cortex (vmPFC). However, to date there is limited brain imaging data to directly test whether psychopathy may indeed be associated with any structural or functional abnormality within this brain area. In this study, we employ two complementary imaging techniques to assess the structural and functional connectivity of vmPFC in psychopathic and non-psychopathic criminals. Using diffusion tensor imaging, we show that psychopathy is associated with reduced structural integrity in the right uncinate fasciculus, the primary white matter connection between vmPFC and anterior temporal lobe. Using functional magnetic resonance imaging, we show that psychopathy is associated with reduced functional connectivity between vmPFC and amygdala as well as between vmPFC and medial parietal cortex. Together, these data converge to implicate diminished vmPFC connectivity as a characteristic neurobiological feature of psychopathy.

Rheological measurements in reduced gravity

Science.gov (United States)

Bakhtiyarov, Sayavur I.; Overfelt, Ruel A.

1999-01-01

Rheology of fluidized beds and settling suspensions were studied experimentally in a series of reduced gravity parabolic flights aboard NASA's KC-135 aircraft. Silica sands of two different size distributions were fluidized by air. The slurries were made using silica sand and Glycerol solution. The experimental set up incorporated instrumentation to measure the air flow rate, the pressure drop and the apparent viscosity of the fluidized sand and sand suspensions at a wide range of the shear rates. The fluidization chamber and container had transparent walls to allow visualization of the structure changes involved in fluidization and in Couette flow in reduced gravity. Experiments were performed over a broad range of gravitational accelerations including microgravity and double gravity conditions. The results of the flight and ground experiments reveal significant differences in overall void fraction and hence in the apparent viscosity of fluidized sand and sand suspensions under microgravity as compared to one-g conditions.

Simulation of sediment settling in reduced gravity

Science.gov (United States)

Kuhn, Nikolaus; Kuhn, Brigitte; Rüegg, Hans-Rudolf; Gartmann, Andres

2015-04-01

Gravity has a non-linear effect on the settling velocity of sediment particles in liquids and gases due to the interdependence of settling velocity, drag and friction. However, Stokes' Law or similar empirical models, the common way of estimating the terminal velocity of a particle settling in a gas or liquid, carry the notion of a drag as a property of a particle, rather than a force generated by the flow around the particle. For terrestrial applications, this simplifying assumption is not relevant, but it may strongly influence the terminal velocity achieved by settling particles on other planetary bodies. False estimates of these settling velocities will, in turn, affect the interpretation of particle sizes observed in sedimentary rocks, e.g. on Mars and the search for traces of life. Simulating sediment settling velocities on other planets based on a numeric simulation using Navier-Stokes equations and Computational Fluid Dynamics requires a prohibitive amount of time and lacks measurements to test the quality of the results. The aim of the experiments presented in this study was therefore to quantify the error incurred by using settling velocity models calibrated on Earth at reduced gravities, such as those on the Moon and Mars. In principle, the effect of lower gravity on settling velocity can be achieved by reducing the difference in density between particle and liquid. However, the use of such analogues creates other problems because the properties (i.e. viscosity) and interaction of the liquids and sediment (i.e. flow around the boundary layer between liquid and particle) differ from those of water and mineral particles. An alternative for measuring the actual settling velocities of particles under reduced gravity, on Earth, is offered by placing a settling tube on a reduced gravity flight and conduct settling velocity measurements within the 20 to 25 seconds of Martian gravity that can be simulated during such a flight. In this presentation, the results

Column-Oriented Storage Techniques for MapReduce

OpenAIRE

Floratou, Avrilia; Patel, Jignesh; Shekita, Eugene; Tata, Sandeep

2011-01-01

Users of MapReduce often run into performance problems when they scale up their workloads. Many of the problems they encounter can be overcome by applying techniques learned from over three decades of research on parallel DBMSs. However, translating these techniques to a MapReduce implementation such as Hadoop presents unique challenges that can lead to new design choices. This paper describes how column-oriented storage techniques can be incorporated in Hadoop in a way that preserves its pop...

Solid Fuel - Oxygen Fired Combustion for Production of Nodular Reduced Iron to Reduce CO2 Emissions and Improve Energy Efficiencies

Energy Technology Data Exchange (ETDEWEB)

Donald R. Fosnacht; Richard F. Kiesel; David W. Hendrickson; David J. Englund; Iwao Iwasaki; Rodney L. Bleifuss; Mathew A. Mlinar

2011-12-22

The current trend in the steel industry is an increase in iron and steel produced in electric arc furnaces (EAF) and a gradual decline in conventional steelmaking from taconite pellets in blast furnaces. In order to expand the opportunities for the existing iron ore mines beyond their blast furnace customer base, a new material is needed to satisfy the market demands of the emerging steel industry while utilizing the existing infrastructure and materials handling capabilities. This demand creates opportunity to convert iron ore or other iron bearing materials to Nodular Reduced Iron (NRI) in a recently designed Linear Hearth Furnace (LHF). NRI is a metallized iron product containing 98.5 to 96.0% iron and 2.5 to 4% C. It is essentially a scrap substitute with little impurity that can be utilized in a variety of steelmaking processes, especially the electric arc furnace. The objective of this project was to focus on reducing the greenhouse gas emissions (GHG) through reducing the energy intensity using specialized combustion systems, increasing production and the use of biomass derived carbon sources in this process. This research examined the use of a solid fuel-oxygen fired combustion system and compared the results from this system with both oxygen-fuel and air-fuel combustion systems. The solid pulverized fuels tested included various coals and a bio-coal produced from woody biomass in a specially constructed pilot scale torrefaction reactor at the Coleraine Minerals Research Laboratory (CMRL). In addition to combustion, the application of bio-coal was also tested as a means to produce a reducing atmosphere during key points in the fusion process, and as a reducing agent for ore conversion to metallic iron to capture the advantage of its inherent reduced carbon footprint. The results from this study indicate that the approaches taken can reduce both greenhouse gas emissions and the associated energy intensity with the Linear Hearth Furnace process for converting

Local stressors reduce coral resilience to bleaching.

Science.gov (United States)

Carilli, Jessica E; Norris, Richard D; Black, Bryan A; Walsh, Sheila M; McField, Melanie

2009-07-22

Coral bleaching, during which corals lose their symbiotic dinoflagellates, typically corresponds with periods of intense heat stress, and appears to be increasing in frequency and geographic extent as the climate warms. A fundamental question in coral reef ecology is whether chronic local stress reduces coral resistance and resilience from episodic stress such as bleaching, or alternatively promotes acclimatization, potentially increasing resistance and resilience. Here we show that following a major bleaching event, Montastraea faveolata coral growth rates at sites with higher local anthropogenic stressors remained suppressed for at least 8 years, while coral growth rates at sites with lower stress recovered in 2-3 years. Instead of promoting acclimatization, our data indicate that background stress reduces coral fitness and resilience to episodic events. We also suggest that reducing chronic stress through local coral reef management efforts may increase coral resilience to global climate change.

Targets set to reduce Lake Erie algae

Science.gov (United States)

Evans, Mary

2016-01-01

In February 2016, the Great Lakes Executive Committee, which oversees the implementation of the Great Lakes Water Quality Agreement (GLWQA) between the U.S. and Canada, approved phosphorus loading targets for Lake Erie to reduce the size of harmful algal blooms (HABs), reduce the presence of the low oxygen zone in the central basin, and protect nearshore water quality. The targets are set with respect to the nutrient loads calculated for 2008. To reduce the impacts of HABs on Lake Erie a target was set of a 40 percent reduction in total and soluble reactive phosphorus loads in the spring from two Canadian rivers and several Michigan and Ohio rivers, especially the Maumee River (https://binational.net/2016/02/22/ finalptargets-ciblesfinalesdep/). States and the province of Ontario are already developing Domestic Action Plans to accomplish the reductions and scientists are developing research and monitoring plans to assess progress.

Contour adaptation reduces the spreading of edge induced colors.

Science.gov (United States)

Coia, Andrew J; Crognale, Michael A

2017-04-25

Brief exposure to flickering achromatic outlines of an area causes a reduction in the brightness contrast of the surface inside the area. This contour adaptation to achromatic contours does not reduce surface contrast when the surface is chromatic (the saturation or colorimetric purity of the surface is maintained). In addition to reducing the brightness of physical luminance contrast, contour adaptation also reduces (or even reverses) the illusory brightness contrast seen in the Craik-O'Brien-Cornsweet illusion, in which two physically identical grey areas appear different brightness because of a sharp luminance edge separating them. Chromatic color spreading illusions also occur with chromatic inducing edges, and an unanswered question is whether contour adaptation can reduce the perceived contrast of illusory color spreading from edges, even though it cannot reduce the perceived contrast of physical surface color. The current studies use a color spreading illusion known as the watercolor effect in order to test whether illusory color spreading is affected by contour adaptation. The general findings of physical achromatic contrast being reduced and chromatic contrast being robust to contour adaptation were replicated. However, both illusory brightness and color were reduced by contour adaptation, even when the illusion edges only differed in chromatic contrast with each other and the background. Additional studies adapting to chromatic contours showed opposite effects on illusory color contrast than achromatic adaptation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Reducing Psychological Resistance to Digital Repositories

Directory of Open Access Journals (Sweden)

Brian Quinn

2010-06-01

Full Text Available The potential value of digital repositories is dependent on the cooperation of scholars to deposit their work. Although many researchers have been resistant to submitting their work, the literature on digital repositories contains very little research on the psychology of resistance. This article looks at the psychological literature on resistance and explores what its implications might be for reducing the resistance of scholars to submitting their work to digital repositories. Psychologists have devised many potentially useful strategies for reducing resistance that might be used to address the problem; this article examines these strategies and how they might be applied.

Biochar amendment reduced methylmercury accumulation in rice plants

Energy Technology Data Exchange (ETDEWEB)

Shu, Rui; Wang, Yongjie [School of Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing, Jiangsu Province, People’s Republic of China (China); Zhong, Huan, E-mail: zhonghuan@nju.edu.cn [School of Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing, Jiangsu Province, People’s Republic of China (China); Environmental and Life Sciences Program (EnLS), Trent University, Peterborough, Ontario (Canada)

2016-08-05

Highlights: • Biochar amendment could evidently reduce methylmercury (MeHg) levels in rice grain. • Biochar could enhance microbial production of MeHg, probably by providing sulfate. • Biochar could immobilize MeHg in soil, and reduce MeHg availability to rice plants. • Biochar amendment increased grain biomass, leading to biodilution of MeHg in grain. - Abstract: There is growing concern about methylmercury (MeHg) accumulation in rice grains and thus enhanced dietary exposure to MeHg in Asian countries. Here, we explored the possibility of reducing grain MeHg levels by biochar amendment, and the underlying mechanisms. Pot (i.e., rice cultivation in biochar amended soils) and batch experiments (i.e., incubation of amended soils under laboratory conditions) were carried out, to investigate MeHg dynamics (i.e., MeHg production, partitioning and phytoavailability in paddy soils, and MeHg uptake by rice) under biochar amendment (1–4% of soil mass). We demonstrate for the first time that biochar amendment could evidently reduce grain MeHg levels (49–92%). The declines could be attributed to the combined effects of: (1) increased soil MeHg concentrations, probably explained by the release of sulfate from biochar and thus enhanced microbial production of MeHg (e.g., by sulfate-reducing bacteria), (2) MeHg immobilization in soils, facilitated by the large surface areas and high organosulfur content of biochar, and (3) biodilution of MeHg in rice grains, due to the increased grain biomass under biochar amendment (35–79%). These observations together with mechanistic explanations improve understanding of MeHg dynamics in soil-rice systems, and support the possibility of reducing MeHg phytoaccumulation under biochar amendment.

Biochar amendment reduced methylmercury accumulation in rice plants

International Nuclear Information System (INIS)

Shu, Rui; Wang, Yongjie; Zhong, Huan

2016-01-01

Highlights: • Biochar amendment could evidently reduce methylmercury (MeHg) levels in rice grain. • Biochar could enhance microbial production of MeHg, probably by providing sulfate. • Biochar could immobilize MeHg in soil, and reduce MeHg availability to rice plants. • Biochar amendment increased grain biomass, leading to biodilution of MeHg in grain. - Abstract: There is growing concern about methylmercury (MeHg) accumulation in rice grains and thus enhanced dietary exposure to MeHg in Asian countries. Here, we explored the possibility of reducing grain MeHg levels by biochar amendment, and the underlying mechanisms. Pot (i.e., rice cultivation in biochar amended soils) and batch experiments (i.e., incubation of amended soils under laboratory conditions) were carried out, to investigate MeHg dynamics (i.e., MeHg production, partitioning and phytoavailability in paddy soils, and MeHg uptake by rice) under biochar amendment (1–4% of soil mass). We demonstrate for the first time that biochar amendment could evidently reduce grain MeHg levels (49–92%). The declines could be attributed to the combined effects of: (1) increased soil MeHg concentrations, probably explained by the release of sulfate from biochar and thus enhanced microbial production of MeHg (e.g., by sulfate-reducing bacteria), (2) MeHg immobilization in soils, facilitated by the large surface areas and high organosulfur content of biochar, and (3) biodilution of MeHg in rice grains, due to the increased grain biomass under biochar amendment (35–79%). These observations together with mechanistic explanations improve understanding of MeHg dynamics in soil-rice systems, and support the possibility of reducing MeHg phytoaccumulation under biochar amendment.

Reduced Attitude Control of a Robotic Underwater Vehicle

Directory of Open Access Journals (Sweden)

Bláha Lukáš

2017-01-01

Full Text Available This paper deals with stabilization and reduced attitude control of a robotic underwater vehicle. The vehicle is assumed to be able to perform a full stable rotations around all axes in underwater space, that is why the standard bottom-heavy structure is not used. The system preferably uses a vectored-thrust arrangement and is built as an overactuated system, which enables to gain a better robustness and guarantees a stable controlled motion even if some thruster suddenly stop working. Because the heading angle cannot be measured, the reduced attitude control strategy is designed and the stability of reduced state of the system is proved using perturbation method.

Reducing transfusion requirements in liver transplantation.

Science.gov (United States)

Donohue, Ciara I; Mallett, Susan V

2015-12-24

Liver transplantation (LT) was historically associated with massive blood loss and transfusion. Over the past two decades transfusion requirements have reduced dramatically and increasingly transfusion-free transplantation is a reality. Both bleeding and transfusion are associated with adverse outcomes in LT. Minimising bleeding and reducing unnecessary transfusions are therefore key goals in the perioperative period. As the understanding of the causes of bleeding has evolved so too have techniques to minimize or reduce the impact of blood loss. Surgical "piggyback" techniques, anaesthetic low central venous pressure and haemodilution strategies and the use of autologous cell salvage, point of care monitoring and targeted correction of coagulopathy, particularly through use of factor concentrates, have all contributed to declining reliance on allogenic blood products. Pre-emptive management of preoperative anaemia and adoption of more restrictive transfusion thresholds is increasingly common as patient blood management (PBM) gains momentum. Despite progress, increasing use of marginal grafts and transplantation of sicker recipients will continue to present new challenges in bleeding and transfusion management. Variation in practice across different centres and within the literature demonstrates the current lack of clear transfusion guidance. In this article we summarise the causes and predictors of bleeding and present the evidence for a variety of PBM strategies in LT.

Perron-Frobenius theory and frequency convergence for reducible substitutions

OpenAIRE

Lustig, Martin; Uyanik, Caglar

2016-01-01

We prove a general version of the classical Perron-Frobenius convergence property for reducible matrices. We then apply this result to reducible substitutions and use it to produce limit frequencies for factors and hence invariant measures on the associated subshift. The analogous results are well known for primitive substitutions and have found many applications, but for reducible substitutions the tools provided here were so far missing from the theory.

Remediation of contaminated subsurface materials by a metal-reducing bacterium

International Nuclear Information System (INIS)

Gorby, Y.A.; Amonette, J.E.; Fruchter, J.S.

1994-11-01

A biotic approach for remediating subsurface sediments and groundwater contaminated with carbon tetrachloride (CT) and chromium was evaluated. Cells of the Fe(iii)-reducing bacterium strain BrY were added to sealed, anoxic flasks containing Hanford groundwater, natural subsurface sediments, and either carbon tetrachloride, CT, or oxidized chromium, Cr(VI). With lactate as the electron donor, BrY transformed CT to chloroform (CF), which accumulated to about 1 0 % of the initial concentration of CT. The remainder of the CT was transformed to unidentified, nonvolatile compounds. Transformation of CT by BrY was an indirect process Cells reduced solid phase Fe(ill) to chemically reactive FE(II) that chemically transformed the chlorinated contaminant. Cr(VI), in contrast, was reduced by a direct enzymatic reaction in the presence or absence of Fe(III)-bearing sediments. These results demonstrate that Fe(ill)-reducing bacteria provide potential for transforming CT and for reducing CR(VI) to less toxic Cr(III). Technologies for stimulating indigenous populations of metal-reducing bacteria or for introducing specific metal-reducing bacteria to the subsurface are being investigated

Sizing Optimization and Strength Analysis for Spread-type Gear Reducers

Directory of Open Access Journals (Sweden)

Wei-Hsuan Hsu

2014-08-01

Full Text Available A reducer is now developed towards the trend of customization service and cost-saving. In this study, a sizing program for the reducer has been developed in order to replace the manual sizing process. We aim at the total center distance of the gear reducer for optimization to reduce gear volume and weight. Also, we checked constrains such as, tooth root bending, tooth contact strength, gear shaft endangered cross-section, bearing life, gear shaft deflection, and torsion angle deformation, etc., to obtain reliable drive strength. Comparisons of sizes and weights before and after optimization confirm that the purpose for reducing production cost is achieved.

Reduced False Memory after Sleep

Science.gov (United States)

Fenn, Kimberly M.; Gallo, David A.; Margoliash, Daniel; Roediger, Henry L., III; Nusbaum, Howard C.

2009-01-01

Several studies have shown that sleep contributes to the successful maintenance of previously encoded information. This research has focused exclusively on memory for studied events, as opposed to false memories. Here we report three experiments showing that sleep reduces false memories in the Deese-Roediger-McDermott (DRM) memory illusion. False…

Reducing Abdominal Fat Deposition in Broiler Through Feeding Management

OpenAIRE

Cecep Hidayat

2015-01-01

Abdominal fat in broiler carcass is considered as a waste and its existence reduces the carcass quality. Abdominal fat deposition is affected by several factors such as genetic, nutrition, feed, sex, age and environment. Reducing abdominal fat deposition can be carried out by regulating the nutrient intake to ensure that no excessive nutrient was consumed. Nutrition effects to reduce abdominal fat deposition are associated with nutrient concentration of ration and quantity of daily feed intak...

Alternative Fuels Data Center: Wisconsin Reduces Emissions With Natural Gas

Science.gov (United States)

Trucks Wisconsin Reduces Emissions With Natural Gas Trucks to someone by E-mail Share Alternative Fuels Data Center: Wisconsin Reduces Emissions With Natural Gas Trucks on Facebook Tweet about Alternative Fuels Data Center: Wisconsin Reduces Emissions With Natural Gas Trucks on Twitter Bookmark

Handgun waiting periods reduce gun deaths.

Science.gov (United States)

Luca, Michael; Malhotra, Deepak; Poliquin, Christopher

2017-11-14

Handgun waiting periods are laws that impose a delay between the initiation of a purchase and final acquisition of a firearm. We show that waiting periods, which create a "cooling off" period among buyers, significantly reduce the incidence of gun violence. We estimate the impact of waiting periods on gun deaths, exploiting all changes to state-level policies in the Unites States since 1970. We find that waiting periods reduce gun homicides by roughly 17%. We provide further support for the causal impact of waiting periods on homicides by exploiting a natural experiment resulting from a federal law in 1994 that imposed a temporary waiting period on a subset of states. Copyright © 2017 the Author(s). Published by PNAS.

The effects of vibration-reducing gloves on finger vibration

Science.gov (United States)

Welcome, Daniel E.; Dong, Ren G.; Xu, Xueyan S.; Warren, Christopher; McDowell, Thomas W.

2015-01-01

Vibration-reducing (VR) gloves have been used to reduce the hand-transmitted vibration exposures from machines and powered hand tools but their effectiveness remains unclear, especially for finger protection. The objectives of this study are to determine whether VR gloves can attenuate the vibration transmitted to the fingers and to enhance the understanding of the mechanisms of how these gloves work. Seven adult male subjects participated in the experiment. The fixed factors evaluated include hand force (four levels), glove condition (gel-filled, air bladder, no gloves), and location of the finger vibration measurement. A 3-D laser vibrometer was used to measure the vibrations on the fingers with and without wearing a glove on a 3-D hand-arm vibration test system. This study finds that the effect of VR gloves on the finger vibration depends on not only the gloves but also their influence on the distribution of the finger contact stiffness and the grip effort. As a result, the gloves increase the vibration in the fingertip area but marginally reduce the vibration in the proximal area at some frequencies below 100 Hz. On average, the gloves reduce the vibration of the entire fingers by less than 3% at frequencies below 80 Hz but increase at frequencies from 80 to 400 Hz. At higher frequencies, the gel-filled glove is more effective at reducing the finger vibration than the air bladder-filled glove. The implications of these findings are discussed. Relevance to industry Prolonged, intensive exposure to hand-transmitted vibration can cause hand-arm vibration syndrome. Vibration-reducing gloves have been used as an alternative approach to reduce the vibration exposure. However, their effectiveness for reducing finger-transmitted vibrations remains unclear. This study enhanced the understanding of the glove effects on finger vibration and provided useful information on the effectiveness of typical VR gloves at reducing the vibration transmitted to the fingers. The new

Learning big data with Amazon Elastic MapReduce

CERN Document Server

Singh, Amarkant

2014-01-01

This book is aimed at developers and system administrators who want to learn about Big Data analysis using Amazon Elastic MapReduce. Basic Java programming knowledge is required. You should be comfortable with using command-line tools. Prior knowledge of AWS, API, and CLI tools is not assumed. Also, no exposure to Hadoop and MapReduce is expected.

Reducing ammonia emissions in Europe

DEFF Research Database (Denmark)

Jacobsen, Brian H.

2011-01-01

The NEC directive has set targets for the 2010 ammonia emissions from a number of European countries. The target will be reached by most EU-countries and the total emission for EU-27 has been reduced by 22% from 1990 to 2007. Denmark is one of the countries with the largest reductions since 1990...

Functional neural correlates of reduced physiological falls risk

Directory of Open Access Journals (Sweden)

Hsu Chun

2011-08-01

Full Text Available Abstract Background It is currently unclear whether the function of brain regions associated with executive cognitive processing are independently associated with reduced physiological falls risk. If these are related, it would suggest that the development of interventions targeted at improving executive neurocognitive function would be an effective new approach for reducing physiological falls risk in seniors. Methods We performed a secondary analysis of 73 community-dwelling senior women aged 65 to 75 years old who participated in a 12-month randomized controlled trial of resistance training. Functional MRI data were acquired while participants performed a modified Eriksen Flanker Task - a task of selective attention and conflict resolution. Brain volumes were obtained using MRI. Falls risk was assessed using the Physiological Profile Assessment (PPA. Results After accounting for baseline age, experimental group, baseline PPA score, and total baseline white matter brain volume, baseline activation in the left frontal orbital cortex extending towards the insula was negatively associated with reduced physiological falls risk over the 12-month period. In contrast, baseline activation in the paracingulate gyrus extending towards the anterior cingulate gyrus was positively associated with reduced physiological falls risk. Conclusions Baseline activation levels of brain regions underlying response inhibition and selective attention were independently associated with reduced physiological falls risk. This suggests that falls prevention strategies may be facilitated by incorporating intervention components - such as aerobic exercise - that are specifically designed to induce neurocognitive plasticity. Trial Registration ClinicalTrials.gov Identifier: NCT00426881

G-Consistent Subsets and Reduced Dynamical Quantum Maps

Science.gov (United States)

Ceballos, Russell R.

A quantum system which evolves in time while interacting with an external environ- ment is said to be an open quantum system (OQS), and the influence of the environment on the unperturbed unitary evolution of the system generally leads to non-unitary dynamics. This kind of open system dynamical evolution has been typically modeled by a Standard Prescription (SP) which assumes that the state of the OQS is initially uncorrelated with the environment state. It is here shown that when a minimal set of physically motivated assumptions are adopted, not only does there exist constraints on the reduced dynamics of an OQS such that this SP does not always accurately describe the possible initial cor- relations existing between the OQS and environment, but such initial correlations, and even entanglement, can be witnessed when observing a particular class of reduced state transformations termed purity extractions are observed. Furthermore, as part of a more fundamental investigation to better understand the minimal set of assumptions required to formulate well defined reduced dynamical quantum maps, it is demonstrated that there exists a one-to-one correspondence between the set of initial reduced states and the set of admissible initial system-environment composite states when G-consistency is enforced. Given the discussions surrounding the requirement of complete positivity and the reliance on the SP, the results presented here may well be found valuable for determining the ba- sic properties of reduced dynamical maps, and when restrictions on the OQS dynamics naturally emerge.

Progress in reducing the environmental impacts of offshore drilling wastes

International Nuclear Information System (INIS)

Flemming, D; Candler, J.E.

2002-01-01

Full text:Over the past several years, great progress has been made in understanding and reducing the environmental impacts of offshore drilling wastes. Our understanding of sea floor impacts has been helped along by new environmental assessment tools such us computer modeling of sea floor deposition of drilling discharges, sediment profile imaging, and in situ sediment toxicity bioassays. To further reduce environmental impacts, new pollution prevention technologies have been developed that can shrink the environmental footprint of offshore drilling. These technologies reduce the total amount of drilling wastes discharged and include cuttings dryers and centrifuges that can reduce the drilling fluid content of drill cuttings to below 10 percent. In conclusion, the oil and gas industry is adopting more environmentally compatible drilling fluids, new environmental assessment tools and pollution prevention technologies that dramatically reduce the amount of drilling wastes discharged. Together, all of these elements have the potential to reduce environmental impacts of offshore drilling

In vitro evaluation of dietary compounds to reduce mercury bioavailability.

Science.gov (United States)

Jadán-Piedra, Carlos; Vélez, Dinoraz; Devesa, Vicenta

2018-05-15

Mercury in foods, in inorganic form [Hg(II)] or as methylmercury (CH 3 Hg), can have adverse effects. Its elimination from foods is not technologically viable. To reduce human exposure, possible alternatives might be based on reducing its intestinal absorption. This study evaluates the ability of 23 dietary components to reduce the amount of mercury that is absorbed and reaches the bloodstream (bioavailability). We determined their effect on uptake of mercury in Caco-2 cells, a model of intestinal epithelium, exposed to Hg(II) and CH 3 Hg standards and to swordfish bioaccessible fractions. Cysteine, homocysteine, glutathione, quercetin, albumin and tannic reduce bioavailability of both mercury species. Fe(II), lipoic acid, pectin, epigallocatechin and thiamine are also effective for Hg(II). Some of these strategies also reduce Hg bioavailability in swordfish (glutathione, cysteine, homocysteine). Moreover, extracts and supplements rich in these compounds are also effective. This knowledge may help to define dietary strategies to reduce in vivo mercury bioavailability. Copyright © 2017 Elsevier Ltd. All rights reserved.

Long Read Alignment with Parallel MapReduce Cloud Platform

Directory of Open Access Journals (Sweden)

Ahmed Abdulhakim Al-Absi

2015-01-01

Full Text Available Genomic sequence alignment is an important technique to decode genome sequences in bioinformatics. Next-Generation Sequencing technologies produce genomic data of longer reads. Cloud platforms are adopted to address the problems arising from storage and analysis of large genomic data. Existing genes sequencing tools for cloud platforms predominantly consider short read gene sequences and adopt the Hadoop MapReduce framework for computation. However, serial execution of map and reduce phases is a problem in such systems. Therefore, in this paper, we introduce Burrows-Wheeler Aligner’s Smith-Waterman Alignment on Parallel MapReduce (BWASW-PMR cloud platform for long sequence alignment. The proposed cloud platform adopts a widely accepted and accurate BWA-SW algorithm for long sequence alignment. A custom MapReduce platform is developed to overcome the drawbacks of the Hadoop framework. A parallel execution strategy of the MapReduce phases and optimization of Smith-Waterman algorithm are considered. Performance evaluation results exhibit an average speed-up of 6.7 considering BWASW-PMR compared with the state-of-the-art Bwasw-Cloud. An average reduction of 30% in the map phase makespan is reported across all experiments comparing BWASW-PMR with Bwasw-Cloud. Optimization of Smith-Waterman results in reducing the execution time by 91.8%. The experimental study proves the efficiency of BWASW-PMR for aligning long genomic sequences on cloud platforms.

Reducing stillbirths in Ethiopia: Results of an intervention programme.

Science.gov (United States)

Lindtjørn, Bernt; Mitike, Demissew; Zidda, Zillo; Yaya, Yaliso

2018-01-01

Previous studies from South Ethiopia have shown that interventions that focus on intrapartum care substantially reduce maternal mortality and there is a need to operationalize health packages that could reduce stillbirths. The aim of this paper is to evaluate if a programme that aimed to improve maternal health, and mainly focusing on strengthening intrapartum care, also would reduce the number of stillbirths, and to estimate if there are other indicators that explains high stillbirth rates. Our study used a "continuum of care" approach and focussed on providing essential antenatal and obstetric services in communities through health extension workers, at antenatal and health facility services. In this follow up study, which includes the same 38.312 births registered by community health workers, shows that interventions focusing on improved intrapartum care can also reduce stillbirths (by 46%; from 14.5 to 7.8 per 1000 births). Other risk factors for stillbirths are mainly related to complications during delivery and illnesses during pregnancy. We show that focusing on Comprehensive Emergency Obstetric Care and antenatal services reduces stillbirths. However, the study also underlines that illnesses during pregnancy and complications during delivery still represent the main risk factors for stillbirths. This indicates that obstetric care need still to be strengthened, should include the continuum of care from home to the health facility, make care accessible to all, and reduce delays.

Long Read Alignment with Parallel MapReduce Cloud Platform

Science.gov (United States)

Al-Absi, Ahmed Abdulhakim; Kang, Dae-Ki

2015-01-01

Genomic sequence alignment is an important technique to decode genome sequences in bioinformatics. Next-Generation Sequencing technologies produce genomic data of longer reads. Cloud platforms are adopted to address the problems arising from storage and analysis of large genomic data. Existing genes sequencing tools for cloud platforms predominantly consider short read gene sequences and adopt the Hadoop MapReduce framework for computation. However, serial execution of map and reduce phases is a problem in such systems. Therefore, in this paper, we introduce Burrows-Wheeler Aligner's Smith-Waterman Alignment on Parallel MapReduce (BWASW-PMR) cloud platform for long sequence alignment. The proposed cloud platform adopts a widely accepted and accurate BWA-SW algorithm for long sequence alignment. A custom MapReduce platform is developed to overcome the drawbacks of the Hadoop framework. A parallel execution strategy of the MapReduce phases and optimization of Smith-Waterman algorithm are considered. Performance evaluation results exhibit an average speed-up of 6.7 considering BWASW-PMR compared with the state-of-the-art Bwasw-Cloud. An average reduction of 30% in the map phase makespan is reported across all experiments comparing BWASW-PMR with Bwasw-Cloud. Optimization of Smith-Waterman results in reducing the execution time by 91.8%. The experimental study proves the efficiency of BWASW-PMR for aligning long genomic sequences on cloud platforms. PMID:26839887

The reduced enrichment program for JRR-4

International Nuclear Information System (INIS)

Takayanagi, M.

1992-01-01

Japan Research Reactor No. 4(JRR-4) with the rated power of 3.5 MW, swimming pool type research reactor, 93 % enriched uranium ETR-type fuel used, light water moderated and cooled. The first criticality reached on 28th January, 1965. The reactor has operated for about 26 years. However, it was planed to the reduced enrichment of the fuels to low enrichment according to the International Reduced Enrichment for Research and Test Reactors (RERTR) program. This paper describes the program for conversion of the enrichment of fuel from 93 % to less than 20 %. (author)

Electron microscopy at reduced levels of irradiation

International Nuclear Information System (INIS)

Kuo, I.A.M.

1975-05-01

Specimen damage by electron radiation is one of the factors that limits high resolution electron microscopy of biological specimens. A method was developed to record images of periodic objects at a reduced electron exposure in order to preserve high resolution structural detail. The resulting image would tend to be a statistically noisy one, as the electron exposure is reduced to lower and lower values. Reconstruction of a statistically defined image from such data is possible by spatial averaging of the electron signals from a large number of identical unit cells. (U.S.)

Some mechanisms which may reduce radiolysis

Energy Technology Data Exchange (ETDEWEB)

Neretnieks, I; Faghihi, M. [Royal Inst. of Tech., Stockholm (Sweden). Dept. of Chemical Engineering

1991-08-01

In this report two mechanisms which may considerably decrease the rate of radiolysis are studied. The first main effect is that capillary forces in the very fine pores of the bentonite which surround the canisters do not permit the release of water if there is a gas over pressure inside the canister. As long as there is gas inside the canister the gap will partly be gas filled and the alpha-particles will have less water to radiolyze. Because some hydrogen will be dissolved and will escape by diffusion, a rate of radiolysis will be maintained which balances the rate of diffusion. This in turn will be influenced by the geometry of the diffusion path. The size of the hole in the copper canister seems to be one of the critical items which determine the escape of the hydrogen and thus the rate of radiolysis. The other main effect which will reduce the radiolysis is the accumulation of the corrosion products in the gap. This reduces the water content in the gap. Consequently there will be less water which can be radiolyzed. The presence of corrosion products which have a higher density than water will also consume the energy of the alpha-particles faster. Both effects seem to, independently, have a potential of reducing the rate of radiolysis by a few order of magnitude.

Some mechanisms which may reduce radiolysis

International Nuclear Information System (INIS)

Neretnieks, I; Faghihi, M.

1991-08-01

In this report two mechanisms which may considerably decrease the rate of radiolysis are studied. The first main effect is that capillary forces in the very fine pores of the bentonite which surround the canisters do not permit the release of water if there is a gas over pressure inside the canister. As long as there is gas inside the canister the gap will partly be gas filled and the alpha-particles will have less water to radiolyze. Because some hydrogen will be dissolved and will escape by diffusion, a rate of radiolysis will be maintained which balances the rate of diffusion. This in turn will be influenced by the geometry of the diffusion path. The size of the hole in the copper canister seems to be one of the critical items which determine the escape of the hydrogen and thus the rate of radiolysis. The other main effect which will reduce the radiolysis is the accumulation of the corrosion products in the gap. This reduces the water content in the gap. Consequently there will be less water which can be radiolyzed. The presence of corrosion products which have a higher density than water will also consume the energy of the alpha-particles faster. Both effects seem to, independently, have a potential of reducing the rate of radiolysis by a few order of magnitude

Monitoring sulfide and sulfate-reducing bacteria

Energy Technology Data Exchange (ETDEWEB)

Tanner, R.S.

1995-12-31

Simple yet precise and accurate methods for monitoring sulfate-reducing bacteria (SRB) and sulfide remain useful for the study of bacterial souring and corrosion. Test kits are available to measure sulfide in field samples. A more precise methylene blue sulfide assay for both field and laboratory studies is described here. Improved media, compared to that in API RP-38, for enumeration of SRB have been formulated. One of these, API-RST, contained cysteine (1.1 mM) as a reducing agent, which may be a confounding source of sulfide. While cysteine was required for rapid enumeration of SRB from environmental samples, the concentration of cysteine in medium could be reduced to 0.4 mM. It was also determined that elevated levels of yeast extract (>1 g/liter) could interfere with enumeration of SRB from environmental samples. The API-RST medium was modified to a RST-11 medium. Other changes in medium composition, in addition to reduction of cysteine, included reduction of the concentration of phosphate from 3.4 mM to 2.2 mM, reduction of the concentration of ferrous iron from 0.8 mM to 0.5 mM and preparation of a stock mineral solution to ease medium preparation. SRB from environmental samples could be enumerated in a week in this medium.

Effect of radiation on activity of sulphate reducing bacteria

International Nuclear Information System (INIS)

Agaev, N.M.; Smorodin, A.E.; Gusejnov, M.M.

1985-01-01

The effect of γ-radiation on activity of sulphate reducing bacteria has been studied. Concentration of biogenic hydrogen, generated in the medium, is the main criterion, characterizing corrosion activity of the bacteria studied. The developed method of suppression of active development of sulfate reducing bacteria considerably reduces, and at lethal doses of γ-radiation eliminates altogether the bacteria activity and formation of the main corrosion agent-hydrogen sulphide-in the medium and that, in its turn, liquidates hydrogen sulphide corrosion

Reducing cement's CO2 footprint

Science.gov (United States)

van Oss, Hendrik G.

2011-01-01

The manufacturing process for Portland cement causes high levels of greenhouse gas emissions. However, environmental impacts can be reduced by using more energy-efficient kilns and replacing fossil energy with alternative fuels. Although carbon capture and new cements with less CO2 emission are still in the experimental phase, all these innovations can help develop a cleaner cement industry.

Alpha-contingent EEG feedback reduces SPECT rCBF variability

DEFF Research Database (Denmark)

McLaughlin, Thomas; Steinberg, Bruce; Mulholland, Thomas

2005-01-01

EEG feedback methods, which link the occurrence of alpha to the presentation of repeated visual stimuli, reduce the relative variability of subsequent, alpha-blocking event durations. The temporal association between electro-cortical field activation and regional cerebral blood flow (rCBF) led us...... to investigate whether the reduced variability of alpha-blocking durations with feedback is associated with a reduction in rCBF variability. Reduced variability in the rCBF response domain under EEG feedback control might have methodological implications for future brain-imaging studies. Visual stimuli were...... to quantify the variance-reducing effects of ACS across multiple, distributed areas of the brain. Both EEG and rCBF measures demonstrated decreased variability under ACS. This improved control was seen for localized as well as anatomically distributed rCBF measures....

Feasibility of Reduced Port Laparoscopic Colectomy for Colon Cancer.

Science.gov (United States)

Tsutsumi, Soichi; Morita, Hiroki; Fujii, Takaaki; Suto, Toshinaga; Yajima, Reina; Takada, Takahiro; Asao, Takayuki; Kuwano, Hiroyuki

2015-06-01

Reduced port laparoscopic surgery has recently emerged as a method to improve the cosmetic results of conventional laparoscopic surgery. We reported our technique of reduced port laparoscopic colectomy using 3-port and short-time outcomes. Between 2005 and 2012, we performed 161 reduced port laparoscopic colectomies using the 3-port technique. Data analyzed in-cluded age, gender, body mass index (BMI), duration of surgery, number of harvested lymph nodes, and duration of hospital stay. All of the cases were successfully performed using the 3-port procedure. The median durations of surgery and postoperative hospital stay were 140 mm (range 75-463 mm) and 9 days (range 5-38 days), respectively. No mortality was associated with this technique. Reduced port laparoscopic colectomy is feasible and may have advantages over conventional laparoscopic colectomy.

Reduced Cortisol Metabolism during Critical Illness

Science.gov (United States)

Boonen, Eva; Vervenne, Hilke; Meersseman, Philippe; Andrew, Ruth; Mortier, Leen; Declercq, Peter E.; Vanwijngaerden, Yoo-Mee; Spriet, Isabel; Wouters, Pieter J.; Perre, Sarah Vander; Langouche, Lies; Vanhorebeek, Ilse; Walker, Brian R.; Van den Berghe, Greet

2015-01-01

BACKGROUND Critical illness is often accompanied by hypercortisolemia, which has been attributed to stress-induced activation of the hypothalamic–pituitary–adrenal axis. However, low corticotropin levels have also been reported in critically ill patients, which may be due to reduced cortisol metabolism. METHODS In a total of 158 patients in the intensive care unit and 64 matched controls, we tested five aspects of cortisol metabolism: daily levels of corticotropin and cortisol; plasma cortisol clearance, metabolism, and production during infusion of deuterium-labeled steroid hormones as tracers; plasma clearance of 100 mg of hydrocortisone; levels of urinary cortisol metabolites; and levels of messenger RNA and protein in liver and adipose tissue, to assess major cortisol-metabolizing enzymes. RESULTS Total and free circulating cortisol levels were consistently higher in the patients than in controls, whereas corticotropin levels were lower (PCortisol production was 83% higher in the patients (P=0.02). There was a reduction of more than 50% in cortisol clearance during tracer infusion and after the administration of 100 mg of hydrocortisone in the patients (P≤0.03 for both comparisons). All these factors accounted for an increase by a factor of 3.5 in plasma cortisol levels in the patients, as compared with controls (Pcortisol clearance also correlated with a lower cortisol response to corticotropin stimulation. Reduced cortisol metabolism was associated with reduced inactivation of cortisol in the liver and kidney, as suggested by urinary steroid ratios, tracer kinetics, and assessment of liver-biopsy samples (P≤0.004 for all comparisons). CONCLUSIONS During critical illness, reduced cortisol breakdown, related to suppressed expression and activity of cortisol-metabolizing enzymes, contributed to hypercortisolemia and hence corticotropin suppression. The diagnostic and therapeutic implications for critically ill patients are unknown. (Funded by the Belgian

Reducibility of quantum representations of mapping class groups

DEFF Research Database (Denmark)

Andersen, Jørgen Ellegaard; Fjelstad, Jens

2010-01-01

that the quantum representations of all the mapping class groups built from the modular tensor category are reducible. In particular, for SU(N) we get reducibility for certain levels and ranks. For the quantum SU(2) Reshetikhin–Turaev theory we construct a decomposition for all even levels. We conjecture...... this decomposition is a complete decomposition into irreducible representations for high enough levels....

Modifying Eating Behavior: Novel Approaches for Reducing Body Weight, Preventing Weight Regain, and Reducing Chronic Disease Risk123

Science.gov (United States)

Gletsu-Miller, Nana; McCrory, Megan A

2014-01-01

This article is a summary of the symposium “Modifying Eating Behavior: Novel Approaches for Reducing Body Weight, Preventing Weight Regain, and Reducing Chronic Disease Risk” held 29 April 2014 at the ASN Scientific Sessions and Annual Meeting at Experimental Biology 2014 in San Diego, CA. In this symposium, novel approaches to modifying eating behavior were highlighted, including 1) alteration of meal timing and macronutrient composition and 2) retraining and provision of feedback about eating behavior. Dr. Ciampolini discussed a method for teaching individuals to recognize a decrease in blood glucose concentration, and therefore the need for energy, by learning the associated physical sensations (signifying hunger). Dr. Madar and Sigal Sofer presented their work on reducing hunger during energy reduction by feeding carbohydrate only in the evening. Dr. Hamilton-Shield reviewed studies on the Mandometer (Mikrodidakt), a device for training individuals to slow eating rate. Finally, Dr. Sazonov presented information on a wearable device, the Automatic Ingestion Monitor, which senses jaw motion and/or hand-to-mouth gestures to detect and characterize food intake. His goal is to use the instrument to prevent overeating by providing feedback to the user to stop ingestion at a predetermined limit. PMID:25398742

21 CFR 146.148 - Reduced acid frozen concentrated orange juice.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 2 2010-04-01 2010-04-01 false Reduced acid frozen concentrated orange juice. 146... Canned Fruit Juices and Beverages § 146.148 Reduced acid frozen concentrated orange juice. (a) Reduced acid frozen concentrated orange juice is the food that complies with the requirements for composition...

Producing Knowledge to Reduce Rhetorical Distance

DEFF Research Database (Denmark)

Kampf, Constance

writers a larger public forum into which they can extend their identity. When the identity being extended represents a minority group, the web offers an opportunity for members of that group to engage mainstream ideology and work at reducing the rhetorical distance between their identity and mainstream......Producing Knowledge to Reduce Rhetorical Distance: Extending Identity and Engaging Mainstream Ideology via the Web Constance Kampf, Department of Research Knowledge Communication, Aarhus School of Business, Denmark McLuhan describes technologies as extensions -the wheel being an extension...... perceptions. This paper theorizes about ways in which the Internet can change the act of producing knowledge through the characteristics of speed and reach, allowing minorities to access a widespread audience much more easily than before the Internet. Access to a widespread audience, in turn, offers...

Deciding for Others Reduces Loss Aversion

DEFF Research Database (Denmark)

Andersson, Ola; Holm, Håkan J.; Tyran, Jean-Robert Karl

2016-01-01

We study risk taking on behalf of others, both when choices involve losses and when they do not. A large-scale incentivized experiment with subjects randomly drawn from the Danish population is conducted. We find that deciding for others reduces loss aversion. When choosing between risky prospects...... when losses loom. This finding is consistent with an interpretation of loss aversion as a bias in decision making driven by emotions and that these emotions are reduced when making decisions for others....... for which losses are ruled out by design, subjects make the same choices for themselves as for others. In contrast, when losses are possible, we find that the two types of choices differ. In particular, we find that subjects who make choices for themselves take less risk than those who decide for others...

Breast Cancer Detection with Reduced Feature Set

Directory of Open Access Journals (Sweden)

Ahmet Mert

2015-01-01

Full Text Available This paper explores feature reduction properties of independent component analysis (ICA on breast cancer decision support system. Wisconsin diagnostic breast cancer (WDBC dataset is reduced to one-dimensional feature vector computing an independent component (IC. The original data with 30 features and reduced one feature (IC are used to evaluate diagnostic accuracy of the classifiers such as k-nearest neighbor (k-NN, artificial neural network (ANN, radial basis function neural network (RBFNN, and support vector machine (SVM. The comparison of the proposed classification using the IC with original feature set is also tested on different validation (5/10-fold cross-validations and partitioning (20%–40% methods. These classifiers are evaluated how to effectively categorize tumors as benign and malignant in terms of specificity, sensitivity, accuracy, F-score, Youden’s index, discriminant power, and the receiver operating characteristic (ROC curve with its criterion values including area under curve (AUC and 95% confidential interval (CI. This represents an improvement in diagnostic decision support system, while reducing computational complexity.

Meta-Transcriptomic Analysis of a Chromate-Reducing Aquifer Microbial Community

Science.gov (United States)

Beller, H. R.; Brodie, E. L.; Han, R.; Karaoz, U.

2010-12-01

A major challenge for microbial ecology that has become more tractable in the advent of new molecular techniques is characterizing gene expression in complex microbial communities. We are using meta-transcriptomic analysis to characterize functional changes in an aquifer-derived, chromate-reducing microbial community as it transitions through various electron-accepting conditions. We inoculated anaerobic microcosms with groundwater from the Cr-contaminated Hanford 100H site and supplemented them with lactate and electron acceptors present at the site, namely, nitrate, sulfate, and Fe(III). The microcosms progressed successively through various electron-accepting conditions (e.g., denitrifying, sulfate-reducing, and ferric iron-reducing conditions, as well as nitrate-dependent, chemolithotrophic Fe(II)-oxidizing conditions). Cr(VI) was rapidly reduced initially and again upon further Cr(VI) amendments. Extensive geochemical sampling and analysis (e.g., lactate, acetate, chloride, nitrate, nitrite, sulfate, dissolved Cr(VI), total Fe(II)), RNA/DNA harvesting, and PhyloChip analyses were conducted. Methods were developed for removal of rRNA from total RNA in preparation for meta-transcriptome sequencing. To date, samples representing denitrifying and fermentative/sulfate-reducing conditions have been sequenced using 454 Titanium technology. Of the non-rRNA related reads for the denitrifying sample (which was also actively reducing chromate), ca. 8% were associated with denitrification and ca. 0.9% were associated with chromate resistance/transport, in contrast to the fermentative/sulfate-reducing sample (in which chromate had already been reduced), which had zero reads associated with either of these categories but many predicted proteins associated with sulfate-reducing bacteria. We observed sequences for key functional transcripts that were unique at the nucleotide level compared to the GenBank non-redundant database [such as L-lactate dehydrogenase (iron

Saving energy and reducing CO2 with electricity

International Nuclear Information System (INIS)

Yau, T.S.; Zaininger, H.W.

1991-10-01

Surprising potential exists for new and enhanced electric technologies to reduce energy use and CO 2 emission. Widespread deployment of these technologies could reduce energy use by up to 7 quads in 2010 and a corresponding reduction in carbon dioxide emission of up to 440 million tons. Electricity's unique high form value allows for efficiency at the point of end-use that is multiples of the efficiency possible in gas- or oil-fueled systems. The efficiency advantage at the point of end use more than offset the disadvantage of the high losses in the production of electricity. Hence, widespread deployment of many electric end uses will reduce the nation's total energy requirements. Major technologies which hold the greatest potential include electric process heating, industrial electrotechnologies, electric vehicles, information technologies that substitute electronic communication for transportation of people, and electric heat pumps for space heating, cooling and water heating. Wider use of these beneficial technologies in combination with the efficient use of electricity can reduce the nation's primary energy use and Co 2 emissions from electric generation by more than a quarter. 35 refs., 50 figs., 69 tabs

Necrostatin-1 Reduces Neurovascular Injury after Intracerebral Hemorrhage

Directory of Open Access Journals (Sweden)

Melanie D. King

2014-01-01

Full Text Available Intracerebral hemorrhage (ICH is the most common form of hemorrhagic stroke, accounting for 15% of all strokes. ICH has the highest acute mortality and the worst long-term prognosis of all stroke subtypes. Unfortunately, the dearth of clinically effective treatment options makes ICH the least treatable form of stroke, emphasizing the need for novel therapeutic targets. Recent work by our laboratory identified a novel role for the necroptosis inhibitor, necrostatin-1, in limiting neurovascular injury in tissue culture models of hemorrhagic injury. In the present study, we tested the hypothesis that necrostatin-1 reduces neurovascular injury after collagenase-induced ICH in mice. Necrostatin-1 significantly reduced hematoma volume by 54% at 72 h after-ICH, as compared to either sham-injured mice or mice administered an inactive, structural analogue of necrostatin-1. Necrostatin-1 also limited cell death by 48%, reduced blood-brain barrier opening by 51%, attenuated edema development to sham levels, and improved neurobehavioral outcomes after ICH. These data suggest a potential clinical utility for necrostatin-1 and/or novel necroptosis inhibitors as an adjunct therapy to reduce neurological injury and improve patient outcomes after ICH.

Strategies to reduce sodium intake in the United States

National Research Council Canada - National Science Library

Henney, Jane E; Taylor, Christine Lewis; Boon, Caitlin S

2010-01-01

"Reducing the intake of sodium is an important public health goal for Americans. Since the 1970s, an array of public health interventions and national dietary guidelines has sought to reduce sodium intake. However, the U.S...

Welfare-Reducing Trade Liberalization

DEFF Research Database (Denmark)

Schröder, Philipp J.H.; Jørgensen, Jan G.

Recent literature on the workhorse model of intra-industry trade has explored heterogeneous cost structures at the firm level. These approaches have proven to add realism and predictive power. This note shows, however, that this added realism also implies that there may exist a positive bilateral...... tariff that maximizes national and world welfare. Applying one of the simplest specifications possible, namely a symmetric two-country intra-industry trade model with fixed export costs that are heterogeneous across firms, we find that the reciprocal reduction of small tariffs reduces welfare. We explore...

Welfare-Reducing Trade Liberalization

DEFF Research Database (Denmark)

Schröder, Philipp J.H.; Jørgensen, Jan G.

Recent literature on the workhorse model of intra-industry trade has explored heterogeneous cost structures at the firm level. These approaches have proven to add realism and predictive power. This paper shows, however, that this added realism also implies that there may exist a positive bilateral...... tariff that maximizes national and world welfare. Applying one of the simplest specifications possible, namely a symmetric two-country intra-industry trade model with fixed export costs that are heterogeneous across firms, we find that the reciprocal reduction of small tariffs reduces welfare....

Reduced cost of ownership

International Nuclear Information System (INIS)

Wyse, W.H.; Newton, J.C.

1995-01-01

There is common drive throughout industry towards reduced costs of ownership of plant and equipment. Rolls-Royce and Associates Ltd. has developed the systems and expertise necessary to achieve these objectives. This Paper outlines the methods being used on existing facilities, and describes a new all embracing process called Planned Lifetime Management. This process, based on the military standard Integrated Logistic Support, ensures that all aspects of support are clearly identified at the design stage and that support is monitored to allow through-life support costs to be optimized. (author)

Localized sulfate-reducing zones in a coastal plain aquifer

Science.gov (United States)

Brown, C.J.; Coates, J.D.; Schoonen, M.A.A.

1999-01-01

High concentrations of dissolved iron in ground water of coastal plain or alluvial aquifers contribute to the biofouling of public supply wells for which treatment and remediation is costly. Many of these aquifers, however, contain zones in which microbial sulfate reduction and the associated precipitation of iron-sulfide minerals decreases iron mobility. The principal water-bearing aquifer (Magothy Aquifer of Cretaceous age) in Suffolk County, New York, contains localized sulfate-reducing zones in and near lignite deposits, which generally are associated with clay lenses. Microbial analyses of core samples amended with [14C]-acetate indicate that microbial sulfate reduction is the predominant terminal-electron-accepting process (TEAP) in poorly permeable, lignite-rich sediments at shallow depths and near the ground water divide. The sulfate-reducing zones are characterized by abundant lignite and iron-sulfide minerals, low concentrations of Fe(III) oxyhydroxides, and by proximity to clay lenses that contain pore water with relatively high concentrations of sulfate and dissolved organic carbon. The low permeability of these zones and, hence, the long residence time of ground water within them, permit the preservation and (or) allow the formation of iron-sulfide minerals, including pyrite and marcasite. Both sulfate-reducing bacteria (SRB) and iron-reducing bacteria (IRB) are present beneath and beyond the shallow sulfate-reducing zones. A unique Fe(III)-reducing organism, MD-612, was found in core sediments from a depth of 187 m near the southern shore of Long Island. The distribution of poorly permeable, lignite-rich, sulfate-reducing zones with decreased iron concentration is varied within the principal aquifer and accounts for the observed distribution of dissolved sulfate, iron, and iron sulfides in the aquifer. Locating such zones for the placement of production wells would be difficult, however, because these zones are of limited aerial extent.

Strategies to Reduce Greenhouse Gas Emissions from Laparoscopic Surgery.

Science.gov (United States)

Thiel, Cassandra L; Woods, Noe C; Bilec, Melissa M

2018-04-01

To determine the carbon footprint of various sustainability interventions used for laparoscopic hysterectomy. We designed interventions for laparoscopic hysterectomy from approaches that sustainable health care organizations advocate. We used a hybrid environmental life cycle assessment framework to estimate greenhouse gas emissions from the proposed interventions. We conducted the study from September 2015 to December 2016 at the University of Pittsburgh (Pittsburgh, Pennsylvania). The largest carbon footprint savings came from selecting specific anesthetic gases and minimizing the materials used in surgery. Energy-related interventions resulted in a 10% reduction in carbon footprint per case but would result in larger savings for the whole facility. Commonly implemented approaches, such as recycling surgical waste, resulted in less than a 5% reduction in greenhouse gases. To reduce the environmental emissions of surgeries, health care providers need to implement a combination of approaches, including minimizing materials, moving away from certain heat-trapping anesthetic gases, maximizing instrument reuse or single-use device reprocessing, and reducing off-hour energy use in the operating room. These strategies can reduce the carbon footprint of an average laparoscopic hysterectomy by up to 80%. Recycling alone does very little to reduce environmental footprint. Public Health Implications. Health care services are a major source of environmental emissions and reducing their carbon footprint would improve environmental and human health. Facilities seeking to reduce environmental footprint should take a comprehensive systems approach to find safe and effective interventions and should identify and address policy barriers to implementing more sustainable practices.

29 CFR 825.202 - Intermittent leave or reduced leave schedule.

Science.gov (United States)

2010-07-01

... leave schedule is a leave schedule that reduces an employee's usual number of working hours per workweek, or hours per workday. A reduced leave schedule is a change in the employee's schedule for a period of... 29 Labor 3 2010-07-01 2010-07-01 false Intermittent leave or reduced leave schedule. 825.202...

Two-phase reduced gravity experiments for a space reactor design

International Nuclear Information System (INIS)

Antoniak, Z.I.

1986-08-01

Future space missions envision the use of large nuclear reactors utilizing either a single or a two-phase alkali-metal working fluid. The design and analysis of such reactors require state-of-the-art computer codes that can properly treat alkali-metal flow and heat transfer in a reduced-gravity environment. New flow regime maps, models, and correlations are required if the codes are to be successfully applied to reduced-gravity flow and heat transfer. General plans are put forth for the reduced-gravity experiments which will have to be performed, at NASA facilities, with benign fluids. Data from the reduced-gravity experiments with innocuous fluids are to be combined with normal gravity data from two-phase alkali-metal experiments. Because these reduced-gravity experiments will be very basic, and will employ small test loops of simple geometry, a large measure of commonality exists between them and experiments planned by other organizations. It is recommended that a committee be formed, to coordinate all ongoing and planned reduced gravity flow experiments

Female employment reduces fertility in rural Senegal.

Science.gov (United States)

Van den Broeck, Goedele; Maertens, Miet

2015-01-01

Economic growth and modernization of society are generally associated with fertility rate decreases but which forces trigger this is unclear. In this paper we assess how fertility changes with increased labor market participation of women in rural Senegal. Evidence from high-income countries suggests that higher female employment rates lead to reduced fertility rates but evidence from developing countries at an early stage of demographic transition is largely absent. We concentrate on a rural area in northern Senegal where a recent boom in horticultural exports has been associated with a sudden increase in female off-farm employment. Using survey data we show that employed women have a significantly higher age at marriage and at first childbirth, and significantly fewer children. As causal identification strategy we use instrumental variable and difference-in-differences estimations, combined with propensity score matching. We find that female employment reduces the number of children per woman by 25%, and that this fertility-reducing effect is as large for poor as for non-poor women and larger for illiterate than for literate women. Results imply that female employment is a strong instrument for empowering rural women, reducing fertility rates and accelerating the demographic transition in poor countries. The effectiveness of family planning programs can increase if targeted to areas where female employment is increasing or to female employees directly because of a higher likelihood to reach women with low-fertility preferences. Our results show that changes in fertility preferences not necessarily result from a cultural evolution but can also be driven by sudden and individual changes in economic opportunities.

Does Increased Extraction of Natural Gas Reduce Carbon Emissions?

International Nuclear Information System (INIS)

Aune, F.R.; Golombek, R.; Kittelsen, S.A. C.

2004-01-01

Without an international climate agreement, extraction of more natural gas could reduce emissions of CO2 as more 'clean' natural gas may drive out ''dirty'' coal and oil. Using a computable equilibrium model for the Western European electricity and natural gas markets, we examine whether increased extraction of natural gas in Norway reduces global emissions of CO2. We find that both in the short run and in the long run total emissions are reduced if the additional quantity of natural gas is used in gas power production in Norway. If instead the additional quantity is exported directly, total emissions increase both in the short run and in the long run. However, if modest CO2-taxes are imposed, increased extraction of natural gas will reduce CO2 emissions also when the additional natural gas is exported directed

Numbers for reducible cubic scrolls

Directory of Open Access Journals (Sweden)

Israel Vainsencher

2004-12-01

Full Text Available We show how to compute the number of reducible cubic scrolls of codimension 2 in (math blackboard symbol Pn incident to the appropriate number of linear spaces.Mostramos como calcular o número de rolos cúbicos redutíveis de codimensão 2 em (math blackboard symbol Pn incidentes a espaços lineares apropriados.

Do conditional benefits reduce equilibrium unemployment?

NARCIS (Netherlands)

van der Ploeg, F.

2006-01-01

Although unconditional unemployment benefits destroy jobs in competitive and noncompetitive labor markets, conditional benefits can spur job growth in noncompetitive labor markets. Unconditional benefits reduce the penalty of shirking and misconduct, while conditional benefits increase this penalty.

Breast cancer after bilateral risk-reducing mastectomy

DEFF Research Database (Denmark)

Skytte, A-B; Crüger, Dorthe Gylling; Gerster, M

2011-01-01

This study aims to evaluate the incidence of breast cancer after risk-reducing mastectomy (RRM) in healthy BRCA mutation carriers. This study is a long-term follow-up of 307 BRCA mutation carriers of whom 96 chose RRM. None of the study participants had a previous history of breast or ovarian...... cancer nor had they undergone RRM or risk-reducing bilateral salpingo-oophorectomy (BSO) prior to the time of BRCA testing. The annual incidence of post-mastectomy breast cancer was 0.8% compared with 1.7% in the non-operated group. Implications of these findings in relation to genetic counseling...

Reduced Ang2 expression in aging endothelial cells

International Nuclear Information System (INIS)

Hohensinner, P.J.; Ebenbauer, B.; Kaun, C.; Maurer, G.; Huber, K.; Wojta, J.

2016-01-01

Aging endothelial cells are characterized by increased cell size, reduced telomere length and increased expression of proinflammatory cytokines. In addition, we describe here that aging reduces the migratory distance of endothelial cells. Furthermore, we observe an increase of the quiescence protein Ang1 and a decrease of the endothelial activation protein Ang2 upon aging. Supplementing Ang2 to aged endothelial cells restored their migratory capacity. We conclude that aging shifts the balance of the Ang1/Ang2 network favouring a quiescent state. Activation of endothelial cells in aging might be necessary to enhance wound healing capacities. -- Highlights: •Endothelial cells display signs of aging before reaching proliferative senescence. •Aging endothelial cells express more angiopoietin 1 and less angiopoietin 2 than young endothelial cells. •Migratory capacity is reduced in aging endothelial cells.

Reduced Ang2 expression in aging endothelial cells

Energy Technology Data Exchange (ETDEWEB)

Hohensinner, P.J., E-mail: philipp.hohensinner@meduniwien.ac.at [Department of Internal Medicine II, Medical University of Vienna, Vienna (Austria); Ebenbauer, B. [Department of Internal Medicine II, Medical University of Vienna, Vienna (Austria); Ludwig Boltzmann Cluster for Cardiovascular Research, Vienna (Austria); Kaun, C.; Maurer, G. [Department of Internal Medicine II, Medical University of Vienna, Vienna (Austria); Huber, K. [Ludwig Boltzmann Cluster for Cardiovascular Research, Vienna (Austria); 3rd Medical Department, Wilhelminenhospital, Vienna (Austria); Sigmund Freud University, Medical Faculty, Vienna (Austria); Wojta, J. [Department of Internal Medicine II, Medical University of Vienna, Vienna (Austria); Ludwig Boltzmann Cluster for Cardiovascular Research, Vienna (Austria); Core Facilities, Medical University of Vienna, Vienna (Austria)

2016-06-03

Aging endothelial cells are characterized by increased cell size, reduced telomere length and increased expression of proinflammatory cytokines. In addition, we describe here that aging reduces the migratory distance of endothelial cells. Furthermore, we observe an increase of the quiescence protein Ang1 and a decrease of the endothelial activation protein Ang2 upon aging. Supplementing Ang2 to aged endothelial cells restored their migratory capacity. We conclude that aging shifts the balance of the Ang1/Ang2 network favouring a quiescent state. Activation of endothelial cells in aging might be necessary to enhance wound healing capacities. -- Highlights: •Endothelial cells display signs of aging before reaching proliferative senescence. •Aging endothelial cells express more angiopoietin 1 and less angiopoietin 2 than young endothelial cells. •Migratory capacity is reduced in aging endothelial cells.

Analysis of alternative pathways for reducing nitrogen oxide emissions

Science.gov (United States)

Strategies for reducing tropospheric ozone typically include modifying combustion processes to reduce the formation of nitrogen oxides (NOx) and applying control devices that remove NOx from the exhaust gases of power plants, industrial sources and vehicles. For portions of the ...

Finding the faithless: perceived atheist prevalence reduces anti-atheist prejudice.

Science.gov (United States)

Gervais, Will M

2011-04-01

Although prejudice is typically positively related to relative outgroup size, four studies found converging evidence that perceived atheist prevalence reduces anti-atheist prejudice. Study 1 demonstrated that anti-atheist prejudice among religious believers is reduced in countries in which atheists are especially prevalent. Study 2 demonstrated that perceived atheist prevalence is negatively associated with anti-atheist prejudice. Study 3 demonstrated a causal relationship: Reminders of atheist prevalence reduced explicit distrust of atheists. These results appeared distinct from intergroup contact effects. Study 4 demonstrated that prevalence information decreased implicit atheist distrust. The latter two experiments provide the first evidence that mere prevalence information can reduce prejudice against any outgroup. These findings offer insights about anti-atheist prejudice, a poorly understood phenomenon. Furthermore, they suggest both novel directions for future prejudice research and potential interventions that could reduce a variety of prejudices.

Double laminated reduced graphene/Cu2S/reduced graphene/graphene oxide nanofilms and their photoelectrochemical properties

Institute of Scientific and Technical Information of China (English)

Junwei Li; Xueqi Zhang; Li Song; Min Zhang; Baohang Zhang

2016-01-01

In this work,an efficient photocatalytic material was prepared directly on Indium tin oxide (ITO) glass substrates by fabricating Cu2S and graphene oxide onto graphene for photoelectrochemical (PEC) water splitting.The double laminated reduced graphene/Cu2S/reduced graphene/graphene oxide (RG/Cu2S/RG/GO) nanofilms were characterized,and an enhanced photoelectrochemical response in the visible region was discovered.The photocurrent density of the nanofilms for PEC water splitting was measured to be up to 1.98 mA/cm2,which could be ascribed to the followings:(i) a higher efficiency of light-harvesting because of GO coupling with Cu2S that could broaden the absorbing solar spectrum and enhance the light utilization efficiency;(ii) a stepwise structure of band-edge levels in the Cu2S/GO electrode was constructed;(iii) double laminated electron accelerator (RG) was used in the Cu2S/GO materials to get better electron-injecting efficiency.