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Sample records for reduced residual arabinose

  1. Chrysosporium lucknowense C1 arabinofuranosidases are selective in releasing arabinose from either single or double substituted xylose residues in arabinoxylans.

    PubMed

    Pouvreau, Laurice; Joosten, Rob; Hinz, Sandra W A; Gruppen, Harry; Schols, Henk A

    2011-04-07

    Two novel arabinofuranosidases, Abn7 and Abf3 from Chrysosporium lucknowense (C1), belonging to the glycoside hydrolase family 43 and 51 were purified and characterized. Abn7 is exclusively able to hydrolyze arabinofuranosyl residues at position O-3 of double substituted xylosyl residues in arabinoxylan-derived oligosaccharides, an activity rarely found thus far. Abf3 is able to release arabinose from position O-2 or O-3 of single substituted xyloses. Both enzymes performed optimal at pH 5.0 and 40°C. Combining Abn7 and Abf3 resulted in a synergistic increase in arabinose release from arabinoxylans. This synergistic effect is due to the action of Abf3 on the remaining arabinose residues at position O-2 on single substituted xylosyl residues resulting from the action of Abn7 on double substituted xylosyl residues. Arabinose release was further increased when an endo-1,4-β-xylanase was present during digestion. The efficiency of these arabinohydrolases from C1 on insoluble arabinoxylan substrates is discussed.

  2. Mutations in the L-arabinose operon of Escherichia coli B/r with reduced initiator function.

    PubMed

    Gonzalez, I L; Sheppard, D E

    1977-05-01

    Partial reversion mutants derived from a strain containing a strongly polar initiator-defective mutation (araI1036) in the L-arabinose operon were found to have several characteristics expected of mutants with reduced initiator function. These reversion mutations are cotransduced with the ara region and are probably within the araI region. Furthermore, they permit induction of the L-arabinose operon to a level only one-third of the normal wild-type level. These partially functional initiator regions reduce the expression of structural genes in the cis position only; they function quite independently of wild-type or defective initiator regions in the trans position. These mutants exhibit a two- to threefold increase in the rate of expression of ara operon genes within one-tenth of a generation after a shift of the growth temperature from 28 to 42 degrees C. This suggests that the temperature optimum for initiation of operon expression is higher for the partial revertant strains than it is for strains containing a wild-type initiator region.

  3. Downregulation of a UDP-Arabinomutase Gene in Switchgrass (Panicum virgatum L.) Results in Increased Cell Wall Lignin While Reducing Arabinose-Glycans

    SciTech Connect

    Willis, Jonathan D.; Smith, James A.; Mazarei, Mitra; Zhang, Ji-Yi; Turner, Geoffrey B.; Decker, Stephen R.; Sykes, Robert W.; Poovaiah, Charleson R.; Baxter, Holly L.; Mann, David G. J.; Davis, Mark F.; Udvardi, Michael K.; Peña, Maria J.; Backe, Jason; Bar-Peled, Maor; Stewart, C. N.

    2016-10-26

    Switchgrass (Panicum virgatum L.) is a C4 perennial prairie grass and a dedicated feedstock for lignocellulosic biofuels. Saccharification and biofuel yields are inhibited by the plant cell wall's natural recalcitrance against enzymatic degradation. Plant hemicellulose polysaccharides such as arabinoxylans structurally support and cross-link other cell wall polymers. Grasses predominately have Type II cell walls that are abundant in arabinoxylan, which comprise nearly 25% of aboveground biomass. A primary component of arabinoxylan synthesis is uridine diphosphate (UDP) linked to arabinofuranose (Araf). A family of UDP-arabinopyranose mutase (UAM)/reversible glycosylated polypeptides catalyze the interconversion between UDP-arabinopyranose (UDP-Arap) and UDP-Araf. The expression of a switchgrass arabinoxylan biosynthesis pathway gene, PvUAM1, was decreased via RNAi to investigate its role in cell wall recalcitrance in the feedstock. PvUAM1 encodes a switchgrass homolog of UDP-arabinose mutase, which converts UDP-Arap to UDP-Araf. Southern blot analysis revealed each transgenic line contained between one to at least seven T-DNA insertions, resulting in some cases, a 95% reduction of native PvUAM1 transcript in stem internodes. Transgenic plants had increased pigmentation in vascular tissues at nodes, but were otherwise similar in morphology to the non-transgenic control. Cell wall-associated arabinose was decreased in leaves and stems by over 50%, but there was an increase in cellulose. In addition, there was a commensurate change in arabinose side chain extension. Cell wall lignin composition was altered with a concurrent increase in lignin content and transcript abundance of lignin biosynthetic genes in mature tillers. Enzymatic saccharification efficiency was unchanged in the transgenic plants relative to the control. Plants with attenuated PvUAM1 transcript had increased cellulose and lignin in cell walls. A decrease in cell wall-associated arabinose

  4. Downregulation of a UDP-Arabinomutase Gene in Switchgrass (Panicum virgatum L.) Results in Increased Cell Wall Lignin While Reducing Arabinose-Glycans

    PubMed Central

    Willis, Jonathan D.; Smith, James A.; Mazarei, Mitra; Zhang, Ji-Yi; Turner, Geoffrey B.; Decker, Stephen R.; Sykes, Robert W.; Poovaiah, Charleson R.; Baxter, Holly L.; Mann, David G. J.; Davis, Mark F.; Udvardi, Michael K.; Peña, Maria J.; Backe, Jason; Bar-Peled, Maor; Stewart, C. N.

    2016-01-01

    wall-associated arabinose was expected, which was likely caused by fewer Araf residues in the arabinoxylan. The decrease in arabinoxylan may cause a compensation response to maintain cell wall integrity by increasing cellulose and lignin biosynthesis. In cases in which increased lignin is desired, e.g., feedstocks for carbon fiber production, downregulated UAM1 coupled with altered expression of other arabinoxylan biosynthesis genes might result in even higher production of lignin in biomass. PMID:27833622

  5. Downregulation of a UDP-Arabinomutase Gene in Switchgrass (Panicum virgatum L.) Results in Increased Cell Wall Lignin While Reducing Arabinose-Glycans

    DOE PAGES

    Willis, Jonathan D.; Smith, James A.; Mazarei, Mitra; ...

    2016-10-26

    Switchgrass (Panicum virgatum L.) is a C4 perennial prairie grass and a dedicated feedstock for lignocellulosic biofuels. Saccharification and biofuel yields are inhibited by the plant cell wall's natural recalcitrance against enzymatic degradation. Plant hemicellulose polysaccharides such as arabinoxylans structurally support and cross-link other cell wall polymers. Grasses predominately have Type II cell walls that are abundant in arabinoxylan, which comprise nearly 25% of aboveground biomass. A primary component of arabinoxylan synthesis is uridine diphosphate (UDP) linked to arabinofuranose (Araf). A family of UDP-arabinopyranose mutase (UAM)/reversible glycosylated polypeptides catalyze the interconversion between UDP-arabinopyranose (UDP-Arap) and UDP-Araf. The expression of amore » switchgrass arabinoxylan biosynthesis pathway gene, PvUAM1, was decreased via RNAi to investigate its role in cell wall recalcitrance in the feedstock. PvUAM1 encodes a switchgrass homolog of UDP-arabinose mutase, which converts UDP-Arap to UDP-Araf. Southern blot analysis revealed each transgenic line contained between one to at least seven T-DNA insertions, resulting in some cases, a 95% reduction of native PvUAM1 transcript in stem internodes. Transgenic plants had increased pigmentation in vascular tissues at nodes, but were otherwise similar in morphology to the non-transgenic control. Cell wall-associated arabinose was decreased in leaves and stems by over 50%, but there was an increase in cellulose. In addition, there was a commensurate change in arabinose side chain extension. Cell wall lignin composition was altered with a concurrent increase in lignin content and transcript abundance of lignin biosynthetic genes in mature tillers. Enzymatic saccharification efficiency was unchanged in the transgenic plants relative to the control. Plants with attenuated PvUAM1 transcript had increased cellulose and lignin in cell walls. A decrease in cell wall-associated arabinose was

  6. Virulence Gene Regulation by L-Arabinose in Salmonella enterica.

    PubMed

    López-Garrido, Javier; Puerta-Fernández, Elena; Cota, Ignacio; Casadesús, Josep

    2015-07-01

    Invasion of the intestinal epithelium is a critical step in Salmonella enterica infection and requires functions encoded in the gene cluster known as Salmonella Pathogenicity Island 1 (SPI-1). Expression of SPI-1 genes is repressed by L-arabinose, and not by other pentoses. Transport of L-arabinose is necessary to repress SPI-1; however, repression is independent of L-arabinose metabolism and of the L-arabinose-responsive regulator AraC. SPI-1 repression by L-arabinose is exerted at a single target, HilD, and the mechanism appears to be post-translational. As a consequence of SPI-1 repression, l-arabinose reduces translocation of SPI-1 effectors to epithelial cells and decreases Salmonella invasion in vitro. These observations reveal a hitherto unknown role of L-arabinose in gene expression control and raise the possibility that Salmonella may use L-arabinose as an environmental signal.

  7. Virulence Gene Regulation by l-Arabinose in Salmonella enterica

    PubMed Central

    López-Garrido, Javier; Puerta-Fernández, Elena; Cota, Ignacio; Casadesús, Josep

    2015-01-01

    Invasion of the intestinal epithelium is a critical step in Salmonella enterica infection and requires functions encoded in the gene cluster known as Salmonella Pathogenicity Island 1 (SPI-1). Expression of SPI-1 genes is repressed by l-arabinose, and not by other pentoses. Transport of l-arabinose is necessary to repress SPI-1; however, repression is independent of l-arabinose metabolism and of the l-arabinose-responsive regulator AraC. SPI-1 repression by l-arabinose is exerted at a single target, HilD, and the mechanism appears to be post-translational. As a consequence of SPI-1 repression, l-arabinose reduces translocation of SPI-1 effectors to epithelial cells and decreases Salmonella invasion in vitro. These observations reveal a hitherto unknown role of l-arabinose in gene expression control and raise the possibility that Salmonella may use L-arabinose as an environmental signal. PMID:25991823

  8. Microbial production of xylitol from xylose and L-arabinose: conversion of L-arabitol to xylitol using bacterial oxidoreductases

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Microbial production of xylitol, using hemicellulosic biomass such as agricultural residues, is becoming more attractive for reducing its manufacturing cost. L-arabitol is a particular problem to xylitol production from hemicellulosic hydrolyzates that contain both xylose and L-arabinose because it...

  9. L-arabinose fermenting yeast

    DOEpatents

    Zhang, Min; Singh, Arjun; Knoshaug, Eric; Franden, Mary Ann; Jarvis, Eric; Suominen, Pirkko

    2010-12-07

    An L-arabinose utilizing yeast strain is provided for the production of ethanol by introducing and expressing bacterial araA, araB and araD genes. L-arabinose transporters are also introduced into the yeast to enhance the uptake of arabinose. The yeast carries additional genomic mutations enabling it to consume L-arabinose, even as the only carbon source, and to produce ethanol. Methods of producing ethanol include utilizing these modified yeast strains. ##STR00001##

  10. Identification of an L-arabinose reductase gene in Aspergillus niger and its role in L-arabinose catabolism.

    PubMed

    Mojzita, Dominik; Penttilä, Merja; Richard, Peter

    2010-07-30

    The first enzyme in the pathway for l-arabinose catabolism in eukaryotic microorganisms is a reductase, reducing l-arabinose to l-arabitol. The enzymes catalyzing this reduction are in general nonspecific and would also reduce d-xylose to xylitol, the first step in eukaryotic d-xylose catabolism. It is not clear whether microorganisms use different enzymes depending on the carbon source. Here we show that Aspergillus niger makes use of two different enzymes. We identified, cloned, and characterized an l-arabinose reductase, larA, that is different from the d-xylose reductase, xyrA. The larA is up-regulated on l-arabinose, while the xyrA is up-regulated on d-xylose. There is however an initial up-regulation of larA also on d-xylose but that fades away after about 4 h. The deletion of the larA gene in A. niger results in a slow growth phenotype on l-arabinose, whereas the growth on d-xylose is unaffected. The l-arabinose reductase can convert l-arabinose and d-xylose to their corresponding sugar alcohols but has a higher affinity for l-arabinose. The K(m) for l-arabinose is 54 + or - 6 mm and for d-xylose 155 + or - 15 mm.

  11. L-arabinose fermenting yeast

    SciTech Connect

    Zhang, Min; Singh, Arjun; Suominen, Pirkko; Knoshaug, Eric; Franden, Mary Ann; Jarvis, Eric

    2014-09-23

    An L-arabinose utilizing yeast strain is provided for the production of ethanol by introducing and expressing bacterial araA, araB and araD genes. L-arabinose transporters are also introduced into the yeast to enhance the uptake of arabinose. The yeast carries additional genomic mutations enabling it to consume L-arabinose, even as the only carbon source, and to produce ethanol. A yeast strain engineered to metabolize arabinose through a novel pathway is also disclosed. Methods of producing ethanol include utilizing these modified yeast strains.

  12. L-arabinose fermenting yeast

    DOEpatents

    Zhang, Min; Singh, Arjun; Suominen, Pirkko; Knoshaug, Eric; Franden, Mary Ann; Jarvis, Eric

    2013-02-12

    An L-arabinose utilizing yeast strain is provided for the production of ethanol by introducing and expressing bacterial araA, araB and araD genes. L-arabinose transporters are also introduced into the yeast to enhance the uptake of arabinose. The yeast carries additional genomic mutations enabling it to consume L-arabinose, even as the only carbon source, and to produce ethanol. A yeast strain engineered to metabolize arabinose through a novel pathway is also disclosed. Methods of producing ethanol include utilizing these modified yeast strains.

  13. Heterodimers reveal that two arabinose molecules are required for the normal arabinose response of AraC.

    PubMed

    Rodgers, Michael E; Schleif, Robert

    2012-10-16

    AraC protein, which regulates expression of the l-arabinose operon in Escherichia coli, is a dimer whose DNA binding affinity for pairs of DNA half-sites is controlled by arabinose. Here we have addressed the question of whether the arabinose response of AraC requires the binding of one or two molecules of arabinose. This was accomplished by measuring the DNA dissociation rates of wild-type AraC and heterodimeric AraC constructs in which one subunit is capable of binding arabinose and the other subunit does not bind arabinose. Solutions consisting entirely of heterodimers were formed by spontaneous subunit exchange between two different homodimers, with heterodimers being trapped by the formation of an intersubunit disulfide bond between cysteine residues strategically positioned within the dimerization interface. We found that the normal arabinose response of AraC requires the binding of two arabinose molecules. These results provide additional constraints on mechanistic models for the action of AraC.

  14. Fractionation of sugar beet pulp into pectin, cellulose, and arabinose by arabinases combined with ultrafiltration

    SciTech Connect

    Spangnuolo, M.; Crecchio, C.; Pizzigallo, M.D.R.; Ruggiero, P.

    1999-09-20

    Incubation of beet pulp with two arabinases ({alpha}-L-arabinofuranosidase and endo-arabinase), used singularly or in combination at different units of activity per gram of beet pulp, caused the hydrolysis of arabinasn, which produced a hydrolyzate consisting mainly of arabinose. Pectin and a residue enriched with cellulose were subsequently separated from the incubation mixture. The best enzymatic hydrolysis results were obtained when 100 U/g of beet pulp of each enzyme worked synergistically with yields of 100% arabinose and 91.7% pectin. These yields were higher than those obtained with traditional chemical hydrolysis. The pectin fraction showed a low content of neutral sugar content and the cellulose residue contained only a small amount of pentoses. Semicontinuous hydrolysis with enzyme recycling in an ultrafiltration unit was also carried out to separate arabinose, pectin, and cellulose from beet pulp in 7 cycles of hydrolysis followed by ultrafiltration. The yields of separation were similar to those obtained in batch experiments, with an enzyme consumption reduced by 3.5 times and some significant advantages over batch processes.

  15. Characterization of an L-arabinose isomerase from Bacillus subtilis.

    PubMed

    Kim, Jin-Ha; Prabhu, Ponnandy; Jeya, Marimuthu; Tiwari, Manish Kumar; Moon, Hee-Jung; Singh, Raushan Kumar; Lee, Jung-Kul

    2010-02-01

    An isolated gene from Bacillus subtilis str. 168 encoding a putative isomerase was proposed as an L-arabinose isomerase (L-AI), cloned into Escherichia coli, and its nucleotide sequence was determined. DNA sequence analysis revealed an open reading frame of 1,491 bp, capable of encoding a polypeptide of 496 amino acid residues. The gene was overexpressed in E. coli and the protein was purified using nickel-nitrilotriacetic acid chromatography. The purified enzyme showed the highest catalytic efficiency ever reported, with a k(cat) of 14,504 min(-1) and a k(cat)/K(m) of 121 min(-1) mM(-1) for L-arabinose. A homology model of B. subtilis L-AI was constructed based on the X-ray crystal structure of E. coli L-AI. Molecular dynamics simulation studies of the enzyme with the natural substrate, L-arabinose, and an analogue, D-galactose, shed light on the unique substrate specificity displayed by B. subtilis L-AI only towards L-arabinose. Although L-AIs have been characterized from several other sources, B. subtilis L-AI is distinguished from other L-AIs by its high substrate specificity and catalytic efficiency for L-arabinose.

  16. Phosphoketolase flux in Clostridium acetobutylicum during growth on L-arabinose.

    PubMed

    Sund, Christian J; Liu, Sanchao; Germane, Katherine L; Servinsky, Matthew D; Gerlach, Elliot S; Hurley, Margaret M

    2015-02-01

    Clostridium acetobutylicum's metabolic pathways have been studied for decades due to its metabolic diversity and industrial value, yet many details of its metabolism continue to emerge. The flux through the recently discovered pentose phosphoketolase pathway (PKP) in C. acetobutylicum has been determined for growth on xylose but transcriptional analysis indicated the pathway may have a greater contribution to arabinose metabolism. To elucidate the role of xylulose-5-phosphate/fructose-6-phosphate phosphoketolase (XFP), and the PKP in C. acetobutylicum, experimental and computational metabolic isotope analyses were performed under growth conditions of glucose or varying concentrations of xylose and arabinose. A positional bias in labelling between carbons 2 and 4 of butyrate was found and posited to be due to an enzyme isotope effect of the thiolase enzyme. A correction for the positional bias was applied, which resulted in reduction of residual error. Comparisons between model solutions with low residual error indicated flux through each of the two XFP reactions was variable, while the combined flux of the reactions remained relatively constant. PKP utilization increased with increasing xylose concentration and this trend was further pronounced during growth on arabinose. Mutation of the gene encoding XFP almost completely abolished flux through the PKP during growth on arabinose and resulted in decreased acetate/butyrate ratios. Greater flux through the PKP during growth on arabinose when compared with xylose indicated the pathway's primary role in C. acetobutylicum is arabinose metabolism.

  17. Fungal arabinan and L-arabinose metabolism.

    PubMed

    Seiboth, Bernhard; Metz, Benjamin

    2011-03-01

    L-Arabinose is the second most abundant pentose beside D-xylose and is found in the plant polysaccharides, hemicellulose and pectin. The need to find renewable carbon and energy sources has accelerated research to investigate the potential of L-arabinose for the development and production of biofuels and other bioproducts. Fungi produce a number of extracellular arabinanases, including α-L-arabinofuranosidases and endo-arabinanases, to specifically release L-arabinose from the plant polymers. Following uptake of L-arabinose, its intracellular catabolism follows a four-step alternating reduction and oxidation path, which is concluded by a phosphorylation, resulting in D-xylulose 5-phosphate, an intermediate of the pentose phosphate pathway. The genes and encoding enzymes L-arabinose reductase, L-arabinitol dehydrogenase, L-xylulose reductase, xylitol dehydrogenase, and xylulokinase of this pathway were mainly characterized in the two biotechnological important fungi Aspergillus niger and Trichoderma reesei. Analysis of the components of the L-arabinose pathway revealed a number of specific adaptations in the enzymatic and regulatory machinery towards the utilization of L-arabinose. Further genetic and biochemical analysis provided evidence that L-arabinose and the interconnected D-xylose pathway are also involved in the oxidoreductive degradation of the hexose D-galactose.

  18. A Minimum-Residual Mixed Reduced Basis Method: Exact Residual Certification and Simultaneous Finite-Element Reduced-Basis Refinement

    DTIC Science & Technology

    2014-08-01

    µ)w. The Helmholtz equation — with the wavenumber as the parameter — results from A(w,∇w;µ) = −∇w and C(w;µ) = −µ2w. The form also supports the...reduced basis method for parametrized partial differential equations certified by a dual-norm bound of the residual computed not in the typical finite...effectiveness of the approach for a parametrized reaction-diffusion equation and a parametrized advection-diffusion equation with a corner singularity; not only

  19. Structural insights into conserved L-arabinose metabolic enzymes reveal the substrate binding site of a thermophilic L-arabinose isomerase.

    PubMed

    Lee, Yong-Jik; Lee, Sang-Jae; Kim, Seong-Bo; Lee, Sang Jun; Lee, Sung Haeng; Lee, Dong-Woo

    2014-03-18

    Structural genomics demonstrates that despite low levels of structural similarity of proteins comprising a metabolic pathway, their substrate binding regions are likely to be conserved. Herein based on the 3D-structures of the α/β-fold proteins involved in the ara operon, we attempted to predict the substrate binding residues of thermophilic Geobacillus stearothermophilus L-arabinose isomerase (GSAI) with no 3D-structure available. Comparison of the structures of L-arabinose catabolic enzymes revealed a conserved feature to form the substrate-binding modules, which can be extended to predict the substrate binding site of GSAI (i.e., D195, E261 and E333). Moreover, these data implicated that proteins in the l-arabinose metabolic pathway might retain their substrate binding niches as the modular structure through conserved molecular evolution even with totally different structural scaffolds.

  20. Arabinose induces pellicle formation by Vibrio fischeri.

    PubMed

    Visick, Karen L; Quirke, Kevin P; McEwen, Sheila M

    2013-03-01

    Biofilms are multicellular communities of bacteria attached to a surface and embedded in a protective matrix. In many cases, the signals that induce biofilm formation are unknown. Here, we report that biofilm formation by the marine bacterium Vibrio fischeri can be induced by the addition of arabinose to LBS (Luria-Bertani-salt), a tryptone-based medium. Growth of cells in the presence of 0.2% arabinose, but not other sugars, induced the production of a pellicle at the air/liquid interfaces of static cultures. V. fischeri failed to grow on arabinose as the sole carbon source, suggesting that pellicle production did not occur as a result of increased growth, but experiments using the acid/base indicator phenol red suggested that V. fischeri may partially metabolize arabinose. Pellicle production was independent of the syp polysaccharide locus but was altered upon disruption of the bcs cellulose locus. Through a screen for mutants defective for pellicle production, we found that loss of motility disrupted the formation of the arabinose-induced pellicle. Among the ∼20 mutants that retained motility were strains with insertions in a putative msh pilus locus and a strain with a defect in yidK, which is involved in galactose catabolism. Mutants with the msh gene disrupted grew poorly in the presence of arabinose, while the yidK mutant appeared to be "blind" to the presence of arabinose. Finally, arabinose impaired symbiotic colonization by V. fischeri. This work thus identifies a novel signal and new pathways involved in control of biofilm formation by V. fischeri.

  1. A novel transcriptional regulator of L-arabinose utilization in human gut bacteria.

    PubMed

    Chang, Changsoo; Tesar, Christine; Li, Xiaoqing; Kim, Youngchang; Rodionov, Dmitry A; Joachimiak, Andrzej

    2015-12-02

    Carbohydrate metabolism plays a crucial role in the ecophysiology of human gut microbiota. Mechanisms of transcriptional regulation of sugar catabolism in commensal and prevalent human gut bacteria such as Bacteroides thetaiotaomicron remain mostly unknown. By a combination of bioinformatics and experimental approaches, we have identified an NrtR family transcription factor (BT0354 in B. thetaiotaomicron, BtAraR) as a novel regulator controlling the arabinose utilization genes. L-arabinose was confirmed to be a negative effector of BtAraR. We have solved the crystal structures of the apo and L-arabinose-bound BtAraR proteins, as well as the complex of apo-protein with a specific DNA operator. BtAraR forms a homodimer with each subunit comprised of the ligand-binding Nudix hydrolase-like domain and the DNA-binding winged-helix-turn-helix (wHTH) domain. We have identified the residues involved in binding of L-arabinose and recognition of DNA. The majority of these residues are well conserved in the AraR orthologs in Bacteroidetes. In the structure of the BtAraR-DNA complex, we found the unique interaction of arginine intercalating its guanidinum moiety into the base pair stacking of B-DNA. L-arabinose binding induces movement of wHTH domains, resulting in a conformation unsuitable for DNA binding. Our analysis facilitates reconstruction of the metabolic and regulatory networks involved in carbohydrate utilization in human gut Bacteroides.

  2. Development of an arabinose-fermenting Zymomonas mobilis strain by metabolic pathway engineering.

    PubMed Central

    Deanda, K; Zhang, M; Eddy, C; Picataggio, S

    1996-01-01

    The substrate fermentation range of the ethanologenic bacterium Zymomonas mobilis was expanded to include the pentose sugar, L-arabinose, which is commonly found in agricultural residues and other lignocellulosic biomass. Five genes, encoding L-arabinose isomerase (araA), L-ribulokinase (araB), L-ribulose-5-phosphate-4-epimerase (araD), transaldolase (talB), and transketolase (tktA), were isolated from Escherichia coli and introduced into Z. mobilis under the control of constitutive promoters that permitted their expression even in the presence of glucose. The engineered strain grew on and produced ethanol from L-arabinose as a sole C source at 98% of the maximum theoretical ethanol yield, based on the amount of consumed sugar. This indicates that arabinose was metabolized almost exclusively to ethanol as the sole fermentation product, with little by-product formation. Although no diauxic growth pattern was evident, the microorganism preferentially utilized glucose before arabinose, apparently reflecting the specificity of the indigenous facilitated diffusion transport system. This microorganism may be useful, along with the previously developed xylose-fermenting Z. mobilis (M. Zhang, C. Eddy, K. Deanda, M. Finkelstein, and S. Picataggio, Science 267:240-243, 1995), in a mixed culture for efficient fermentation of the predominant hexose and pentose sugars in agricultural residues and other lignocellulosic feedstocks to ethanol. PMID:8953718

  3. Process for reducing Ramsbottom Carbon Test of long residues

    SciTech Connect

    Eilers, J.; Stork, W.H.J.

    1984-07-17

    Process for the preparation of a heavy oil with a low Ramsbottom Carbon Test (RCT) from a long residue by (a) catalytic hydrotreatment for RCT reduction at such severity that the C/sub 4/- gas production per percentage RCT reduction is kept between defined limits, followed by (b) solvent deasphalting of the (vacuum or atmospheric) distillation residue of the hydrotreated product.

  4. L-arabinose pathway engineering for arabitol-free xylitol production in Candida tropicalis.

    PubMed

    Yoon, Byoung Hoon; Jeon, Woo Young; Shim, Woo Yong; Kim, Jung Hoe

    2011-04-01

    Xylose reductase (XR) is a key enzyme in biological xylitol production, and most XRs have broad substrate specificities. During xylitol production from biomass hydrolysate, non-specific XRs can reduce L-arabinose, which is the second-most abundant hemicellulosic sugar, to the undesirable byproduct arabitol, which interferes with xylitol crystallization in downstream processing. To minimize the flux from L-arabinose to arabitol, the L-arabinose-preferring, endogenous XR was replaced by a D-xylose-preferring heterologous XR in Candida tropicalis. Then, Bacillus licheniformis araA and Escherichia coli araB and araD were codon-optimized and expressed functionally in C. tropicalis for the efficient assimilation of L-arabinose. During xylitol fermentation, the control strains BSXDH-3 and KNV converted 9.9 g L-arabinose l(-1) into 9.5 and 8.3 g arabitol l(-1), respectively, whereas the recombinant strain JY consumed 10.5 g L-arabinose l(-1) for cell growth without forming arabitol. Moreover, JY produced xylitol with 42 and 16% higher productivity than BSXDH-3 and KNV, respectively.

  5. Process for reducing Ramsbottom Carbon Test of short residues

    SciTech Connect

    Eilers, J.; Stork, H.J.

    1984-07-24

    In the preparation of a heavy oil with a low Ramsbottom Carbon Test (RCT) from a long residue by a two-stage process comprising catalytic hydrotreatment followed by solvent deasphalting and recycle of the asphalt to the first stage the catalytic hydrotreatment for RCT reduction in the first stage is carried out at such a severity that the C/sub 4/ - gas production per percent RCT reduction is kept between defined limits.

  6. Protective effects of L-arabinose in high-carbohydrate, high-fat diet-induced metabolic syndrome in rats

    PubMed Central

    Hao, Lei; Lu, Xiaoling; Sun, Min; Li, Kai; Shen, Lingmin; Wu, Tao

    2015-01-01

    Background L-Arabinose is a non-caloric sugar, which could affect glucose and lipid metabolism and suppress obesity. However, few reports have described the effect of L-arabinose in metabolic syndrome, a combination of medical disorders that increase the risk of diabetes and cardiovascular disease. Objective This study was conducted to explore the effects of L-arabinose in rats with metabolic syndrome induced by a high-carbohydrate, high-fat (HCHF) diet. Methods After the rat model for metabolic syndrome was successfully established, L-arabinose was administrated by oral gavage for 6 weeks. The biochemical index and histological analysis were measured, and the expression levels of genes related to fatty acid metabolism were analyzed using real-time PCR. Results Following treatment with L-arabinose, metabolic syndrome rats had an obvious reduction in body weight, systolic blood pressure, diastolic blood pressure, fasting blood glucose, triglycerides, total cholesterol, serum insulin, TNF-α, and leptin. Further study showed that treatment with L-arabinose significantly increased the expression of mRNA for hepatic CPT-1α and PDK4, but the expression of mRNA for hepatic ACCα was reduced. Conclusions This work suggests that L-arabinose could lower body weight, Lee's index, and visceral index and improve dyslipidemia, insulin resistance, inflammation, and viscera function, which indicate that it might be a promising candidate for therapies combating metabolic syndrome. PMID:26652604

  7. The LacI-Type transcriptional regulator AraR acts as an L-arabinose-responsive repressor of L-arabinose utilization genes in Corynebacterium glutamicum ATCC 31831.

    PubMed

    Kuge, Takayuki; Teramoto, Haruhiko; Yukawa, Hideaki; Inui, Masayuki

    2014-06-01

    The Corynebacterium glutamicum ATCC 31831 araBDA operon consists of three l-arabinose catabolic genes, upstream of which the galM, araR, and araE genes are located in opposite orientation. araR encodes a LacI-type transcriptional regulator that negatively regulates the l-arabinose-inducible expression of araBDA and araE (encoding an l-arabinose transporter), through a mechanism that has yet to be identified. Here we show that the AraR protein binds in vitro to three sites: one upstream of araBDA and two upstream of araE. We verify that a 16-bp consensus palindromic sequence is essential for binding of AraR, using a series of mutations introduced upstream of araB in electrophoretic mobility shift assays. Moreover, the DNA-binding activity of AraR is reduced by l-arabinose. We employ quantitative reverse transcription-PCR (qRT-PCR) analyses using various mutant strains deficient in l-arabinose utilization genes to demonstrate that the prominent upregulation of araBDA and araE within 5 min of l-arabinose supplementation is dependent on the uptake but independent of the catabolism of l-arabinose. Similar expression patterns, together with the upregulation by araR disruption without l-arabinose, are evident with the apparent galM-araR operon, although attendant changes in expression levels are much smaller than those realized with the expression of araBDA and araE. The AraR-binding site upstream of araB overlaps the -10 region of the divergent galM promoter. These observations indicate that AraR acts as a transcriptional repressor of araBDA, araE, and galM-araR and that l-arabinose acts as an intracellular negative effector of the AraR-dependent regulation.

  8. A novel L-xylulose reductase essential for L-arabinose catabolism in Trichoderma reesei.

    PubMed

    Metz, Benjamin; Mojzita, Dominik; Herold, Silvia; Kubicek, Christian P; Richard, Peter; Seiboth, Bernhard

    2013-04-09

    L-Xylulose reductases belong to the superfamily of short chain dehydrogenases and reductases (SDRs) and catalyze the NAD(P)H-dependent reduction of L-xylulose to xylitol in L-arabinose and glucuronic acid catabolism. Here we report the identification of a novel L-xylulose reductase LXR3 in the fungus Trichoderma reesei by a bioinformatic approach in combination with a functional analysis. LXR3, a 31 kDa protein, catalyzes the reduction of L-xylulose to xylitol via NADPH and is also able to convert D-xylulose, D-ribulose, L-sorbose, and D-fructose to their corresponding polyols. Transcription of lxr3 is specifically induced by L-arabinose and L-arabitol. Deletion of lxr3 affects growth on L-arabinose and L-arabitol and reduces total NADPH-dependent LXR activity in cell free extracts. A phylogenetic analysis of known L-xylulose reductases shows that LXR3 is phylogenetically different from the Aspergillus niger L-xylulose reductase LxrA and, moreover, that all identified true L-xylulose reductases belong to different clades within the superfamily of SDRs. This indicates that the enzymes responsible for the reduction of L-xylulose in L-arabinose and glucuronic acid catabolic pathways have evolved independently and that even the fungal LXRs of the L-arabinose catabolic pathway have evolved in different clades of the superfamily of SDRs.

  9. A Novel l-Xylulose Reductase Essential for l-Arabinose Catabolism in Trichoderma reesei

    PubMed Central

    2013-01-01

    l-Xylulose reductases belong to the superfamily of short chain dehydrogenases and reductases (SDRs) and catalyze the NAD(P)H-dependent reduction of l-xylulose to xylitol in l-arabinose and glucuronic acid catabolism. Here we report the identification of a novel l-xylulose reductase LXR3 in the fungus Trichoderma reesei by a bioinformatic approach in combination with a functional analysis. LXR3, a 31 kDa protein, catalyzes the reduction of l-xylulose to xylitol via NADPH and is also able to convert d-xylulose, d-ribulose, l-sorbose, and d-fructose to their corresponding polyols. Transcription of lxr3 is specifically induced by l-arabinose and l-arabitol. Deletion of lxr3 affects growth on l-arabinose and l-arabitol and reduces total NADPH-dependent LXR activity in cell free extracts. A phylogenetic analysis of known l-xylulose reductases shows that LXR3 is phylogenetically different from the Aspergillus nigerl-xylulose reductase LxrA and, moreover, that all identified true l-xylulose reductases belong to different clades within the superfamily of SDRs. This indicates that the enzymes responsible for the reduction of l-xylulose in l-arabinose and glucuronic acid catabolic pathways have evolved independently and that even the fungal LXRs of the l-arabinose catabolic pathway have evolved in different clades of the superfamily of SDRs. PMID:23506391

  10. A novel transcriptional regulator of L-arabinose utilization in human gut bacteria

    DOE PAGES

    Chang, Changsoo; Tesar, Christine; Li, Xiaoqing; ...

    2015-10-04

    We report that carbohydrate metabolism plays a crucial role in the ecophysiology of human gut microbiota. Mechanisms of transcriptional regulation of sugar catabolism in commensal and prevalent human gut bacteria such as Bacteroides thetaiotaomicron remain mostly unknown. By a combination of bioinformatics and experimental approaches, we have identified an NrtR family transcription factor (BT0354 in B. thetaiotaomicron, BtAraR) as a novel regulator controlling the arabinose utilization genes. L-arabinose was confirmed to be a negative effector of BtAraR. We have solved the crystal structures of the apo and L-arabinose-bound BtAraR proteins, as well as the complex of apo-protein with a specificmore » DNA operator. BtAraR forms a homodimer with each subunit comprised of the ligand-binding Nudix hydrolase-like domain and the DNA-binding winged-helix-turn-helix (wHTH) domain. We have identified the residues involved in binding of L-arabinose and recognition of DNA. The majority of these residues are well conserved in the AraR orthologs in Bacteroidetes. In the structure of the BtAraR–DNA complex, we found the unique interaction of arginine intercalating its guanidinum moiety into the base pair stacking of B-DNA. L-arabinose binding induces movement of wHTH domains, resulting in a conformation unsuitable for DNA binding. Furthermore, our analysis facilitates reconstruction of the metabolic and regulatory networks involved in carbohydrate utilization in human gut Bacteroides.« less

  11. A novel transcriptional regulator of L-arabinose utilization in human gut bacteria

    SciTech Connect

    Chang, Changsoo; Tesar, Christine; Li, Xiaoqing; Kim, Youngchang; Rodionov, Dmitry A.; Joachimiak, Andrzej

    2015-10-04

    We report that carbohydrate metabolism plays a crucial role in the ecophysiology of human gut microbiota. Mechanisms of transcriptional regulation of sugar catabolism in commensal and prevalent human gut bacteria such as Bacteroides thetaiotaomicron remain mostly unknown. By a combination of bioinformatics and experimental approaches, we have identified an NrtR family transcription factor (BT0354 in B. thetaiotaomicron, BtAraR) as a novel regulator controlling the arabinose utilization genes. L-arabinose was confirmed to be a negative effector of BtAraR. We have solved the crystal structures of the apo and L-arabinose-bound BtAraR proteins, as well as the complex of apo-protein with a specific DNA operator. BtAraR forms a homodimer with each subunit comprised of the ligand-binding Nudix hydrolase-like domain and the DNA-binding winged-helix-turn-helix (wHTH) domain. We have identified the residues involved in binding of L-arabinose and recognition of DNA. The majority of these residues are well conserved in the AraR orthologs in Bacteroidetes. In the structure of the BtAraR–DNA complex, we found the unique interaction of arginine intercalating its guanidinum moiety into the base pair stacking of B-DNA. L-arabinose binding induces movement of wHTH domains, resulting in a conformation unsuitable for DNA binding. Furthermore, our analysis facilitates reconstruction of the metabolic and regulatory networks involved in carbohydrate utilization in human gut Bacteroides.

  12. Enzymatic saccharification of sugar beet pulp for the production of galacturonic acid and arabinose; a study on the impact of the formation of recalcitrant oligosaccharides.

    PubMed

    Leijdekkers, A G M; Bink, J P M; Geutjes, S; Schols, H A; Gruppen, H

    2013-01-01

    Enzymatic saccharification of sugar beet pulp was optimized on kg-scale to release the maximum amounts of monomeric galacturonic acid and arabinose with limited concomitant degradation of cellulose, using conditions that are feasible for industrial upscaling. A selected mixture of pectinases released 79% of the galacturonic acid and 82% of the arabinose as monomers from sugar beet pulp while simultaneously degrading only 17% of the cellulose. The recalcitrant structures that were obtained after hydrolysis were characterized using mass spectrometry. The most abundant structures had an average degree of polymerization of 4-5. They were identified as partially acetylated rhamnogalacturonan-oligosaccharides, mostly containing a terminal galacturonosyl residue on both reducing and non-reducing end, partially methyl esterified/acetylated homogalacturonan-oligosaccharides, mostly containing methyl and acetyl esters at contiguous galacturonosyl residues and arabinan-oligosaccharides, hypothesized to be mainly branched. It could be concluded that especially rhamnogalacturonan-galacturonohydrolase, arabinofuranosidase and pectin acetylesterase are lacking for further degradation of recalcitrant oligosaccharides.

  13. Improving N credit predictions to reduce residual nitrate

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The potential to increase farm profitability and reduce nitrate leaching in Minnesota are huge if the alfalfa N credit was better understood and applied to first-year corn. If the N credit (150 lb/N/ac) were applied to the nearly 250,000 acres of corn following alfalfa in Minnesota each year, 19,000...

  14. Influence of hydrophobic and superhydrophobic surfaces on reducing aerodynamic insect residues

    NASA Astrophysics Data System (ADS)

    Krishnan, K. Ghokulla; Milionis, Athanasios; Loth, Eric; Farrell, Thomas E.; Crouch, Jeffrey D.; Berry, Douglas H.

    2017-01-01

    Insect fouling during takeoff, climb and landing can result in increased drag and fuel consumption for aircrafts with laminar-flow surfaces. This study investigates the effectiveness of various hydrophobic and superhydrophobic surfaces in reducing residue of insects on an aerodynamic surface at relatively high impact speeds (about 45 m/s). An experimental setup consisting of a wind tunnel and a method to inject live flightless fruit flies was used to test the effectiveness of various surfaces against insect fouling. Insect fouling was analyzed based on residue area and height from multiple impacts. In general most of the residue area was due to the hemolymph spreading while most of the residue height was due to adhesion of exoskeleton parts. Hydrophobic and especially superhydrophobic surfaces performed better than a hydrophilic aluminum surface in terms of minimizing the residue area of various insect components (exoskeleton, hemolymph, and red fluid). Surfaces with reduced wettability and short lateral length scales tended to have the smallest residue area. Residue height was not as strongly influenced by surface wettability since even a single exoskeleton adhered to the surface upon impact was enough to produce a residue height of the order of one mm. In general, the results indicate that hemolymph spread needs to be avoided (e.g. by having reduced wettability and short lateral correlation lengths) in order to minimize the residue area, while exoskeleton adherence needs to be avoided (e.g. by having oleophobic properties and micro/nano roughness) in order to minimize the residue height. In particular, two of the superhydrophobic coatings produced substantial reduction in residue height and area, relative to the baseline surface of aluminum. However, the surfaces also showed poor mechanical durability on the high-speed insect impact location. This suggests that although low wettability materials show great insect anti-fouling behavior, their durability needs to

  15. Heterologous expression and characterization of Bacillus coagulans L-arabinose isomerase.

    PubMed

    Zhou, Xingding; Wu, Jin Chuan

    2012-05-01

    Bacillus coagulans has been of great commercial interest over the past decade owing to its strong ability of producing optical pure L: -lactic acid from both hexose and pentose sugars including L: -arabinose with high yield, titer and productivity under thermophilic conditions. The L: -arabinose isomerase (L-AI) from Bacillus coagulans was heterologously over-expressed in Escherichia coli. The open reading frame of the L-AI has 1,422 nucleotides encoding a protein with 474 amino acid residues. The recombinant L-AI was purified to homogeneity by one-step His-tag affinity chromatography. The molecular mass of the enzyme was estimated to be 56 kDa by SDS-PAGE. The enzyme was most active at 70°C and pH 7.0. The metal ion Mn(2+) was shown to be the best activator for enzymatic activity and thermostability. The enzyme showed higher activity at acidic pH than at alkaline pH. The kinetic studies showed that the K (m), V (max) and k (cat)/K (m) for the conversion of L: -arabinose were 106 mM, 84 U/mg and 34.5 mM(-1)min(-1), respectively. The equilibrium ratio of L: -arabinose to L: -ribulose was 78:22 under optimal conditions. L: -ribulose (97 g/L) was obtained from 500 g/l of L: -arabinose catalyzed by the enzyme (8.3 U/mL) under the optimal conditions within 1.5 h, giving at a substrate conversion of 19.4% and a production rate of 65 g L(-1) h(-1).

  16. Sugar-metal ion interactions: The coordination behavior of cesium ion with lactose, D-arabinose and L-arabinose

    NASA Astrophysics Data System (ADS)

    Jiang, Ye; Xue, Junhui; Wen, Xiaodong; Zhai, Yanjun; Yang, Limin; Xu, Yizhuang; Zhao, Guozhong; Kou, Kuan; Liu, Kexin; Chen, Jia'er; Wu, Jinguang

    2016-04-01

    The novel cesium chloride-lactose complex (CsCl·C12H22O10 (Cs-Lac), cesium chloride-D-arabinose and L-arabinose complexes (CsCl·C5H10O5, Cs-D-Ara and Cs-L-Ara) have been synthesized and characterized using X-ray diffraction, FTIR, FIR, THz and Raman spectroscopies. Cs+ is 9-coordinated to two chloride ions and seven hydroxyl groups from five lactose molecules in Cs-Lac. In the structures of CsCl-D-arabinose and CsCl-L-arabinose complexes, two kinds of Cs+ ions coexist in the structures. Cs1 is 10-coordinated with two chloride ions and eight hydroxyl groups from five arabinose molecule; Cs2 is 9-coordinated to three chloride ions and six hydroxyl groups from five arabinose molecules. Two coordination modes of arabinose coexist in the structures. α-D-arabinopyranose and α-L-arabinopyranose appear in the structures of Cs-D-Ara and Cs-L-Ara complexes. FTIR and Raman results indicate variations of hydrogen bonds and the conformation of the ligands after complexation. FIR and THz spectra also confirm the formation of Cs-complexes. Crystal structure, FTIR, FIR, THz and Raman spectra provide detailed information on the structure and coordination of hydroxyl groups to metal ions in the cesium chloride-lactose, cesium chloride-D- and L-arabinose complexes.

  17. Roller Burnishing - A Cold Working Tool to Reduce Weld Induced Residual Stress

    SciTech Connect

    John Martin

    2002-02-19

    The possibility of stress corrosion cracking (SCC) in regions of tensile residual stress introduced by weld deposited material has been a concern where environmental effects can reduce component life. Roller burnishing, a form of mechanical cold-working, has been considered as a means of providing for residual stress state improvements. This paper provides a computational evaluation of the roller burnishing process to address the permanent deformation needed to introduce a desirable residual stress state. The analysis uses a series of incrementally applied pressure loadings and finite element methodology to simulate the behavior of a roller burnishing tool. Various magnitudes of applied pressure loadings coupled with different size plates and boundary conditions are examined to assess the degree and depth of the residual compressive stress state after cold working. Both kinematic and isotropic hardening laws are evaluated.

  18. Biosynthesis of D-arabinose in mycobacteria - a novel bacterial pathway with implications for antimycobacterial therapy.

    PubMed

    Wolucka, Beata A

    2008-06-01

    Decaprenyl-phospho-arabinose (beta-D-arabinofuranosyl-1-O-monophosphodecaprenol), the only known donor of d-arabinose in bacteria, and its precursor, decaprenyl-phospho-ribose (beta-D-ribofuranosyl-1-O-monophosphodecaprenol), were first described in 1992. En route to D-arabinofuranose, the decaprenyl-phospho-ribose 2'-epimerase converts decaprenyl-phospho-ribose to decaprenyl-phospho-arabinose, which is a substrate for arabinosyltransferases in the synthesis of the cell-wall arabinogalactan and lipoarabinomannan polysaccharides of mycobacteria. The first step of the proposed decaprenyl-phospho-arabinose biosynthesis pathway in Mycobacterium tuberculosis and related actinobacteria is the formation of D-ribose 5-phosphate from sedoheptulose 7-phosphate, catalysed by the Rv1449 transketolase, and/or the isomerization of d-ribulose 5-phosphate, catalysed by the Rv2465 d-ribose 5-phosphate isomerase. d-Ribose 5-phosphate is a substrate for the Rv1017 phosphoribosyl pyrophosphate synthetase which forms 5-phosphoribosyl 1-pyrophosphate (PRPP). The activated 5-phosphoribofuranosyl residue of PRPP is transferred by the Rv3806 5-phosphoribosyltransferase to decaprenyl phosphate, thus forming 5'-phosphoribosyl-monophospho-decaprenol. The dephosphorylation of 5'-phosphoribosyl-monophospho-decaprenol to decaprenyl-phospho-ribose by the putative Rv3807 phospholipid phosphatase is the committed step of the pathway. A subsequent 2'-epimerization of decaprenyl-phospho-ribose by the heteromeric Rv3790/Rv3791 2'-epimerase leads to the formation of the decaprenyl-phospho-arabinose precursor for the synthesis of the cell-wall arabinans in Actinomycetales. The mycobacterial 2'-epimerase Rv3790 subunit is similar to the fungal D-arabinono-1,4-lactone oxidase, the last enzyme in the biosynthesis of D-erythroascorbic acid, thus pointing to an evolutionary link between the D-arabinofuranose- and L-ascorbic acid-related pathways. Decaprenyl-phospho-arabinose has been a lead compound for the

  19. Teichuronic acid reducing terminal N-acetylglucosamine residue linked by phosphodiester to peptidoglycan of Micrococcus luteus

    SciTech Connect

    Gassner, G.T.; Dickie, J.P.; Hamerski, D.A.; Magnuson, J.K.; Anderson, J.S. )

    1990-05-01

    Teichuronic acid-peptidoglycan complex isolated from Micrococcus luteus cells by lysozyme digestion in osmotically stabilized medium was treated with mild acid to cleave the linkage joining teichuronic acid to peptidoglycan. This labile linkage was shown to be the phosphodiester which joins N-acetylglucosamine, the residue located at the reducing end of the teichuronic acid, through its anomeric hydroxyl group to a 6-phosphomuramic acid, a residue of the glycan strand of peptidoglycan. {sup 31}P nuclear magnetic resonance spectroscopy of the lysozyme digest of cell walls demonstrated the presence of a phosphodiester which was converted to a phosphomonoester by the conditions which released teichuronic acid from cell walls. Reduction of acid-liberated reducing end groups by NaB{sup 3}H{sub 4} followed by complete acid hydrolysis yielded ({sup 3}H) glucosaminitol from the true reducing end residue of teichuronic acid and ({sup 3}H)glucitol from the sites of fragmentation of teichuronic acid. The amount of N-acetylglucosamine detected was approximately stoichiometric with the amount of phosphate in the complex. Partial fragmentation of teichuronic acid provides an explanation of the previous erroneous identification of the reducing end residue.

  20. Single Zymomonas mobilis strain for xylose and arabinose fermentation

    DOEpatents

    Zhang, M.; Chou, Y.C.; Picataggio, S.K.; Finkelstein, M.

    1998-12-01

    This invention relates to single microorganisms which normally do not ferment pentose sugars which are genetically altered to ferment the pentose sugars, xylose and arabinose, to produce ethanol, and a fermentation process utilizing the same. Examples include Zymomonas mobilis which has been transformed with a combination of E. coli genes for xylose isomerase, xylulokinase, L-arabinose isomerase, L-ribulokinase, L-ribulose 5-phosphate 4-epimerase, transaldolase and transketolase. Expression of added genes are under the control of Z. mobilis promoters. These newly created microorganisms are useful for fermenting glucose, xylose and arabinose, produced by hydrolysis of hemicellulose and cellulose or starch, to produce ethanol. 6 figs.

  1. Single zymomonas mobilis strain for xylose and arabinose fermentation

    DOEpatents

    Zhang, Min; Chou, Yat-Chen; Picataggio, Stephen K.; Finkelstein, Mark

    1998-01-01

    This invention relates to single microorganisms which normally do not ferment pentose sugars which are genetically altered to ferment the pentose sugars, xylose and arabinose, to produce ethanol, and a fermentation process utilizing the same. Examples include Zymomonas mobilis which has been transformed with a combination of E. coli genes for xylose isomerase, xylulokinase, L-arabinose isomerase, L-ribulokinase, L-ribulose 5-phosphate 4-epimerase, transaldolase and transketolase. Expression of added genes are under the control of Z. mobilis promoters. These newly created microorganisms are useful for fermenting glucose, xylose and arabinose, produced by hydrolysis of hemicellulose and cellulose or starch, to produce ethanol.

  2. Cloning of two genes (LAT1,2) encoding specific L: -arabinose transporters of the L: -arabinose fermenting yeast Ambrosiozyma monospora.

    PubMed

    Verho, Ritva; Penttilä, Merja; Richard, Peter

    2011-07-01

    We identified and characterized two genes, LAT1 and LAT2, which encode specific L: -arabinose transporters. The genes were identified in the L: -arabinose fermenting yeast Ambrosiozyma monospora. The yeast Saccharomyces cerevisiae had only very low L: -arabinose transport activity; however, when LAT1 or LAT2 was expressed, L: -arabinose transport was facilitated. When the LAT1 or LAT2 were expressed in an S. cerevisiae mutant where the main hexose transporters were deleted, the L: -arabinose transporters could not restore growth on D: -glucose, D: -fructose, D: -mannose or D: -galactose. This indicates that these sugars are not transported and suggests that the transporters are specific for L: -arabinose.

  3. L-Arabinose degradation pathway in the haloarchaeon Haloferax volcanii involves a novel type of L-arabinose dehydrogenase.

    PubMed

    Johnsen, Ulrike; Sutter, Jan-Moritz; Zaiß, Henning; Schönheit, Peter

    2013-11-01

    The pathway of L-arabinose degradation was studied in the haloarchaeon Haloferax volcanii. It is shown that L-arabinose is oxidatively degraded to α-ketoglutarate. During growth on L-arabinose, L-arabinose dehydrogenase (L-AraDH) was induced. The enzyme was purified as a 130 kDa homotetrameric protein catalyzing the oxidation of L-arabinose with both NADP(+) and NAD(+). The gene encoding L-AraDH was identified as HVO_B0032 and recombinant L-AraDH showed similar properties as the native enzyme. The L-AraDH deletion mutant did not grow on L-arabinose, but grew unaffected on glucose and D-xylose, indicating a specific involvement in L-arabinose degradation. Phylogenetic analyses attribute the first archaeal L-AraDH to the extended short-chain dehydrogenase/reductase (SDRe) family, where it is part of a novel cluster and thus differs from known archaeal and bacterial pentose dehydrogenases. Further, cell extracts of H. volcanii catalyzed the NADP(+)-dependent conversion of L-arabinoate to α-ketoglutarate. The genes involved in that conversion were identified by analyses of transcripts and deletion mutants as HVO_B0038A, HVO_B0027 and HVO_B0039 recently reported to be involved in D-xylonate conversion to α-ketoglutarate in H. volcanii (Johnsen et al. 2009).

  4. Concurrent tailoring of fabrication process and interphase layer to reduce residual stresses in metal matrix composites

    NASA Technical Reports Server (NTRS)

    Saravanos, D. A.; Chamis, C. C.; Morel, M.

    1991-01-01

    A methodology is presented to reduce the residual matrix stresses in continuous fiber metal matrix composites (MMC) by optimizing the fabrication process and interphase layer characteristics. The response of the fabricated MMC was simulated based on nonlinear micromechanics. Application cases include fabrication tailoring, interphase tailoring, and concurrent fabrication-interphase optimization. Two composite systems, silicon carbide/titanium and graphite/copper, are considered. Results illustrate the merits of each approach, indicate that concurrent fabrication/interphase optimization produces significant reductions in the matrix residual stresses and demonstrate the strong coupling between fabrication and interphase tailoring.

  5. Methods to Reduce Forest Residue Volume after Timber Harvesting and Produce Black Carbon

    PubMed Central

    Busse, Matt D.; Archuleta, James G.; McAvoy, Darren; Roussel, Eric

    2017-01-01

    Forest restoration often includes thinning to reduce tree density and improve ecosystem processes and function while also reducing the risk of wildfire or insect and disease outbreaks. However, one drawback of these restoration treatments is that slash is often burned in piles that may damage the soil and require further restoration activities. Pile burning is currently used on many forest sites as the preferred method for residue disposal because piles can be burned at various times of the year and are usually more controlled than broadcast burns. In many cases, fire can be beneficial to site conditions and soil properties, but slash piles, with a large concentration of wood, needles, forest floor, and sometimes mineral soil, can cause long-term damage. We describe several alternative methods for reducing nonmerchantable forest residues that will help remove excess woody biomass, minimize detrimental soil impacts, and create charcoal for improving soil organic matter and carbon sequestration. PMID:28377830

  6. Novel stereospecificity of the L-arabinose-binding protein

    NASA Astrophysics Data System (ADS)

    Quiocho, Florante A.; Vyas, Nand K.

    1984-08-01

    Tertiary structure refinement at 1.7 Å resolution of the liganded form of L-arabinose-binding protein from Escherichia coli has revealed a novel binding site geometry which accommodates both α- and β-anomers of L-arabinose. This detailed structure analysis provides new understanding of protein-sugar interaction, the process by which the binding protein minimizes the difference in the stability of the two bound sugar anomers, and the roles of periplasmic binding proteins in active transport

  7. Treatment intensification does not reduce residual HIV-1 viremia in patients on highly active antiretroviral therapy.

    PubMed

    Dinoso, J B; Kim, S Y; Wiegand, A M; Palmer, S E; Gange, S J; Cranmer, L; O'Shea, A; Callender, M; Spivak, A; Brennan, T; Kearney, M F; Proschan, M A; Mican, J M; Rehm, C A; Coffin, J M; Mellors, J W; Siliciano, R F; Maldarelli, F

    2009-06-09

    In HIV-1-infected individuals on currently recommended antiretroviral therapy (ART), viremia is reduced to <50 copies of HIV-1 RNA per milliliter, but low-level residual viremia appears to persist over the lifetimes of most infected individuals. There is controversy over whether the residual viremia results from ongoing cycles of viral replication. To address this question, we conducted 2 prospective studies to assess the effect of ART intensification with an additional potent drug on residual viremia in 9 HIV-1-infected individuals on successful ART. By using an HIV-1 RNA assay with single-copy sensitivity, we found that levels of viremia were not reduced by ART intensification with any of 3 different antiretroviral drugs (efavirenz, lopinavir/ritonavir, or atazanavir/ritonavir). The lack of response was not associated with the presence of drug-resistant virus or suboptimal drug concentrations. Our results suggest that residual viremia is not the product of ongoing, complete cycles of viral replication, but rather of virus output from stable reservoirs of infection.

  8. Regulation of arabinose and xylose metabolism in Escherichia coli.

    PubMed

    Desai, Tasha A; Rao, Christopher V

    2010-03-01

    Bacteria such as Escherichia coli will often consume one sugar at a time when fed multiple sugars, in a process known as carbon catabolite repression. The classic example involves glucose and lactose, where E. coli will first consume glucose, and only when it has consumed all of the glucose will it begin to consume lactose. In addition to that of lactose, glucose also represses the consumption of many other sugars, including arabinose and xylose. In this work, we characterized a second hierarchy in E. coli, that between arabinose and xylose. We show that, when grown in a mixture of the two pentoses, E. coli will consume arabinose before it consumes xylose. Consistent with a mechanism involving catabolite repression, the expression of the xylose metabolic genes is repressed in the presence of arabinose. We found that this repression is AraC dependent and involves a mechanism where arabinose-bound AraC binds to the xylose promoters and represses gene expression. Collectively, these results demonstrate that sugar utilization in E. coli involves multiple layers of regulation, where cells will consume first glucose, then arabinose, and finally xylose. These results may be pertinent in the metabolic engineering of E. coli strains capable of producing chemical and biofuels from mixtures of hexose and pentose sugars derived from plant biomass.

  9. Priority of pentose utilization at the level of transcription: arabinose, xylose, and ribose operons.

    PubMed

    Kang, H Y; Song, S; Park, C

    1998-06-30

    When E. coli cells were grown in minimal medium supplemented with D-ribose and D-xylose, a diauxic growth preferring D-xylose was observed. Transcription of the ribose (rbs) operon was repressed in the presence of D-xylose, phenotypically similar to catabolite repression by D-glucose, although D-ribose did not affect transcription of the xylose (xyl) operon. Complementation analysis with xylR revealed that the repression of the rbs operon by D-xylose is exerted at the transcriptional level through XylR, suggesting a novel mechanism for catabolite repression. Furthermore, it was shown that L-arabinose reduced transcriptions of both xyl and rbs operons, whereas the arabinose operon was not affected by D-xylose or D-ribose, suggesting a priority mechanism for pentose utilization.

  10. The effect of various frequencies of ultrasonic cleaner in reducing residual monomer in acrylic resin.

    PubMed

    Charasseangpaisarn, Taksid; Wiwatwarrapan, Chairat

    2015-12-01

    Monomer remaining in denture base acrylic can be a major problem because it may cause adverse effects on oral tissue and on the properties of the material. The purpose of this study was to compare the effect of various ultrasonic cleaner frequencies on the amount of residual monomer in acrylic resin after curing. Forty-two specimens each of Meliodent heat-polymerized acrylic resin (M) and Unifast Trad Ivory auto-polymerized acrylic resin (U) were prepared according to their manufacturer's instructions and randomly divided into seven groups: Negative control (NC); Positive control (PC); and five ultrasonic treatment groups: 28 kHz (F1), 40 kHz (F2), 60 kHz (F3) (M=10 min, U=5 min), and 28 kHz followed by 60 kHz (F4: M=5 min per frequency, U=2.5 min per frequency, and F5: M=10 min followed by 5 min per frequency, U=5 min followed by 2.5 min per frequency). Residual monomer was determined by HPLC following ISO 20795-1. The data were analyzed by One-way ANOVA and Tukey HSD. There was significantly less residual monomer in the auto-polymerized acrylic resin in all ultrasonic treatment groups and the PC group than that of the NC group (p<0.05). However, the amount of residual monomer in group F3 was significantly higher than that of the F1, F4, and PC groups (p<0.05). In contrast, ultrasonic treatment did not reduce the amount of residual monomer in heat-polymerized acrylic resin (p>0.05). The amount of residual monomer in heat-polymerized acrylic resin was significantly lower than that of auto-polymerized acrylic resin. In conclusion, ultrasonic treatment at low frequencies is recommended to reduce the residual monomer in auto-polymerized acrylic resin and this method is more practical in a clinical situation than previously recommended methods because of reduced chairside time.

  11. Enhanced coagulation for improving coagulation performance and reducing residual aluminum combining polyaluminum chloride with diatomite.

    PubMed

    Hu, Wenchao; Wu, Chunde

    2016-01-01

    The feasibility of using enhanced coagulation, which combined polyaluminum chloride (PAC) with diatomite for improving coagulation performance and reducing the residual aluminum (Al), was discussed. The effects of PAC and diatomite dosage on the coagulation performance and residual Al were mainly investigated. Results demonstrated that the removal efficiencies of turbidity, dissolved organic carbon (DOC), and UV254 were significantly improved by the enhanced coagulation, compared with PAC coagulation alone. Meaningfully, the five forms of residual Al (total Al (TAl), total dissolved Al (TDAl), dissolved organic Al (DOAl), dissolved monomeric Al (DMAl), and dissolved organic monomeric Al (DOMAl)) all had different degrees of reduction in the presence of diatomite and achieved the lowest concentrations (0.185, 0.06, 0.053, 0.014, and 0 mg L(-1), respectively) at a PAC dose of 15 mg L(-1) and diatomite dose of 40 mg L(-1). In addition, when PAC was used as coagulant, the majority of residual Al existed in dissolved form (about 31.14-70.16%), and the content of DOMAl was small in the DMAl.

  12. Expression of E. coli araBAD operon encoding enzymes for metabolizing L-arabinose in Saccharomyces cerevisiae.

    PubMed

    Sedlak; Ho

    2001-01-02

    The Escherichia coli araBAD operon consists of three genes encoding three enzymes that convert L-arabinose to D-xylulose-5 phosphate. In this paper we report that the genes of the E. coli araBAD operon have been expressed in Saccharomyces cerevisiae using strong promoters from genes encoding S. cerevisiae glycolytic enzymes (pyruvate kinase, phosphoglucose isomerase, and phosphoglycerol kinase). The expression of these cloned genes in yeast was demonstrated by the presence of the active enzymes encoded by these cloned genes and by the presence of the corresponding mRNAs in the new host. The level of expression of L-ribulokinase (araB) and L-ribulose-5-phosphate 4-epimerase (araD) in S. cerevisiae was relatively high, with greater than 70% of the activity of the enzymes in wild type E. coli. On the other hand, the expression of L-arabinose isomerase (araA) reached only 10% of the activity of the same enzyme in wild type E. coli. Nevertheless, S. cerevisiae, bearing the cloned L-arabinose isomerase gene, converted L-arabinose to detectable levels of L-ribulose during fermentation. However, S. cerevisiae bearing all three genes (araA, araB, and araD) was not able to produce detectable amount of ethanol from L-arabinose. We speculate that factors such as pH, temperature, and competitive inhibition could reduce the activity of these enzymes to a lower level during fermentation compared to their activity measured in vitro. Thus, the ethanol produced from L-arabinose by recombinant yeast containing the expressed BAD genes is most likely totally consumed by the cell to maintain viability.

  13. Functional Analysis of Two l-Arabinose Transporters from Filamentous Fungi Reveals Promising Characteristics for Improved Pentose Utilization in Saccharomyces cerevisiae.

    PubMed

    Li, Jingen; Xu, Jing; Cai, Pengli; Wang, Bang; Ma, Yanhe; Benz, J Philipp; Tian, Chaoguang

    2015-06-15

    Limited uptake is one of the bottlenecks for l-arabinose fermentation from lignocellulosic hydrolysates in engineered Saccharomyces cerevisiae. This study characterized two novel l-arabinose transporters, LAT-1 from Neurospora crassa and MtLAT-1 from Myceliophthora thermophila. Although the two proteins share high identity (about 83%), they display different substrate specificities. Sugar transport assays using the S. cerevisiae strain EBY.VW4000 indicated that LAT-1 accepts a broad substrate spectrum. In contrast, MtLAT-1 appeared much more specific for l-arabinose. Determination of the kinetic properties of both transporters revealed that the Km values of LAT-1 and MtLAT-1 for l-arabinose were 58.12 ± 4.06 mM and 29.39 ± 3.60 mM, respectively, with corresponding Vmax values of 116.7 ± 3.0 mmol/h/g dry cell weight (DCW) and 10.29 ± 0.35 mmol/h/g DCW, respectively. In addition, both transporters were found to use a proton-coupled symport mechanism and showed only partial inhibition by d-glucose during l-arabinose uptake. Moreover, LAT-1 and MtLAT-1 were expressed in the S. cerevisiae strain BSW2AP containing an l-arabinose metabolic pathway. Both recombinant strains exhibited much faster l-arabinose utilization, greater biomass accumulation, and higher ethanol production than the control strain. In conclusion, because of higher maximum velocities and reduced inhibition by d-glucose, the genes for the two characterized transporters are promising targets for improved l-arabinose utilization and fermentation in S. cerevisiae.

  14. Characteristics of α-L-arabinofuranosidase from Streptomyces sp I10-1 for production of L-arabinose from corn hull arabinoxylan.

    PubMed

    Kurakake, Masahiro; Kanbara, Yoshikazu; Murakami, Yoshiki

    2014-03-01

    Streptomyces sp I10-1 α-L-arabinofuranosidase efficiently produced L-arabinose from high arabinose-content corn hull arabinoxylan (ratio of arabinose to xylose, 0.6). The optimum pH at 40 °C was around 6, and the enzyme was stable from pH 5 to 11. The optimum temperature was 50 °C at pH 5, and the activity was stable at 40 °C. The enzymatic activity against corn hull arabinoxylan was 2.3 times higher than towards p-nitrophenyl-α-L-arabinofuranoside. Approximately 45% L-arabinose recovery was achieved from corn hull arabinoxylan. It was considered that L-arabinose residues not removed by the enzyme were attributable to those linked with ferulic acid. The open reading frame of the enzyme gene consisted of 1,224 bp, and the predicted peptide was 408 amino acids, which corresponded to a molecular size of 45, 248 Da. It was presumed that the smaller molecular size (31,000 Da) estimated on SDS-PAGE resulted from proteolysis by proteases. I10-1 α-L-arabinofuranosidase belongs to the Alpha-L-AF C superfamily, which is associated with glycoside hydrolase family 51, but the properties were unique.

  15. A link between arabinose utilization and oxalotrophy in Bradyrhizobium japonicum.

    PubMed

    Koch, Marion; Delmotte, Nathanaël; Ahrens, Christian H; Omasits, Ulrich; Schneider, Kathrin; Danza, Francesco; Padhi, Barnali; Murset, Valérie; Braissant, Olivier; Vorholt, Julia A; Hennecke, Hauke; Pessi, Gabriella

    2014-04-01

    Rhizobia have a versatile catabolism that allows them to compete successfully with other microorganisms for nutrients in the soil and in the rhizosphere of their respective host plants. In this study, Bradyrhizobium japonicum USDA 110 was found to be able to utilize oxalate as the sole carbon source. A proteome analysis of cells grown in minimal medium containing arabinose suggested that oxalate oxidation extends the arabinose degradation branch via glycolaldehyde. A mutant of the key pathway genes oxc (for oxalyl-coenzyme A decarboxylase) and frc (for formyl-coenzyme A transferase) was constructed and shown to be (i) impaired in growth on arabinose and (ii) unable to grow on oxalate. Oxalate was detected in roots and, at elevated levels, in root nodules of four different B. japonicum host plants. Mixed-inoculation experiments with wild-type and oxc-frc mutant cells revealed that oxalotrophy might be a beneficial trait of B. japonicum at some stage during legume root nodule colonization.

  16. Regulation of the L-arabinose operon of Escherichia coli.

    PubMed

    Schleif, R

    2000-12-01

    Over forty years of research on the L-arabinose operon of Escherichia coli have provided insights into the mechanism of positive regulation of gene activity. This research also discovered DNA looping and the mechanism by which the regulatory protein changes its DNA-binding properties in response to the presence of arabinose. As is frequently seen in focused research on biological subjects, the initial studies were primarily genetic. Subsequently, the genetic approaches were augmented by physiological and then biochemical studies. Now biophysical studies are being conducted at the atomic level, but genetics still has a crucial role in the study of this system.

  17. Hydride vapor phase GaN films with reduced density of residual electrons and deep traps

    SciTech Connect

    Polyakov, A. Y.; Smirnov, N. B.; Govorkov, A. V.; Yugova, T. G.; Cox, H.; Helava, H.; Makarov, Yu.; Usikov, A. S.

    2014-05-14

    Electrical properties and deep electron and hole traps spectra are compared for undoped n-GaN films grown by hydride vapor phase epitaxy (HVPE) in the regular process (standard HVPE samples) and in HVPE process optimized for decreasing the concentration of residual donor impurities (improved HVPE samples). It is shown that the residual donor density can be reduced by optimization from ∼10{sup 17} cm{sup −3} to (2–5) × 10{sup 14} cm{sup −3}. The density of deep hole traps and deep electron traps decreases with decreased donor density, so that the concentration of deep hole traps in the improved samples is reduced to ∼5 × 10{sup 13} cm{sup −3} versus 2.9 × 10{sup 16} cm{sup −3} in the standard samples, with a similar decrease in the electron traps concentration.

  18. Fuel ethanol production from L-arabinose: Constraints, challenges, current status and future trends

    SciTech Connect

    Saha, B.C.; Bothast, R.J.

    1995-12-01

    Interest in fermentation of L-arabinose to ethanol has increased in recent years because corn fiber contains 11% L-arabinose and is available in sufficient quantities to serve as a low cost feedstock to produce fuel ethanol. Various L-arabinose utilizing yeasts were screened for cost feedstock to produce fuel ethanol of their ability to ferment L-arabinose to ethanol. Most yeasts produced L-arabitol instead ethanol. The optimal conditions for production of L-arabitol in high yield from L-arabinose alone, in mixed sugars and in corn fiber acid hydrolyzate by certain yeasts will be described. In addition, the fermentative performance of an ethanologenic recombinant organism on L-arabinose will be discussed. Current status of microbial fermentation of L-arabinose to ethanol, problems and prospects of ethanol production from L-arabinose by yeasts and future directions of research will be reviewed.

  19. Microbial Production of Xylitol from L-arabinose by Metabolically Engineered Escherichia coli

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An Escherichia coli strain, ZUC99(pATX210), which can produce xylitol from L-arabinose at a high yield has been created by introducing a new bioconversion pathway into cells. This pathway consists of three enzymes: L-arabinose isomerase, which converts L-arabinose to L-ribulose; D-psicose 3-epimer...

  20. Combining contact tracing with targeted indoor residual spraying significantly reduces dengue transmission.

    PubMed

    Vazquez-Prokopec, Gonzalo M; Montgomery, Brian L; Horne, Peter; Clennon, Julie A; Ritchie, Scott A

    2017-02-01

    The widespread transmission of dengue viruses (DENV), coupled with the alarming increase of birth defects and neurological disorders associated with Zika virus, has put the world in dire need of more efficacious tools for Aedes aegypti-borne disease mitigation. We quantitatively investigated the epidemiological value of location-based contact tracing (identifying potential out-of-home exposure locations by phone interviews) to infer transmission foci where high-quality insecticide applications can be targeted. Space-time statistical modeling of data from a large epidemic affecting Cairns, Australia, in 2008-2009 revealed a complex pattern of transmission driven primarily by human mobility (Cairns accounted for ~60% of virus transmission to and from residents of satellite towns, and 57% of all potential exposure locations were nonresidential). Targeted indoor residual spraying with insecticides in potential exposure locations reduced the probability of future DENV transmission by 86 to 96%, compared to unsprayed premises. Our findings provide strong evidence for the effectiveness of combining contact tracing with residual spraying within a developed urban center, and should be directly applicable to areas with similar characteristics (for example, southern USA, Europe, or Caribbean countries) that need to control localized Aedes-borne virus transmission or to protect pregnant women's homes in areas with active Zika transmission. Future theoretical and empirical research should focus on evaluation of the applicability and scalability of this approach to endemic areas with variable population size and force of DENV infection.

  1. Combining contact tracing with targeted indoor residual spraying significantly reduces dengue transmission

    PubMed Central

    Vazquez-Prokopec, Gonzalo M.; Montgomery, Brian L.; Horne, Peter; Clennon, Julie A.; Ritchie, Scott A.

    2017-01-01

    The widespread transmission of dengue viruses (DENV), coupled with the alarming increase of birth defects and neurological disorders associated with Zika virus, has put the world in dire need of more efficacious tools for Aedes aegypti–borne disease mitigation. We quantitatively investigated the epidemiological value of location-based contact tracing (identifying potential out-of-home exposure locations by phone interviews) to infer transmission foci where high-quality insecticide applications can be targeted. Space-time statistical modeling of data from a large epidemic affecting Cairns, Australia, in 2008–2009 revealed a complex pattern of transmission driven primarily by human mobility (Cairns accounted for ~60% of virus transmission to and from residents of satellite towns, and 57% of all potential exposure locations were nonresidential). Targeted indoor residual spraying with insecticides in potential exposure locations reduced the probability of future DENV transmission by 86 to 96%, compared to unsprayed premises. Our findings provide strong evidence for the effectiveness of combining contact tracing with residual spraying within a developed urban center, and should be directly applicable to areas with similar characteristics (for example, southern USA, Europe, or Caribbean countries) that need to control localized Aedes-borne virus transmission or to protect pregnant women’s homes in areas with active Zika transmission. Future theoretical and empirical research should focus on evaluation of the applicability and scalability of this approach to endemic areas with variable population size and force of DENV infection. PMID:28232955

  2. Alternative DNA loops regulate the arabinose operon in Escherichia coli.

    PubMed

    Huo, L; Martin, K J; Schleif, R

    1988-08-01

    The araCBAD regulatory region of Escherichia coli contains two divergently oriented promoters and three sites to which AraC, the regulatory protein of the operon, can bind. This paper presents the results of in vivo dimethyl sulfate "footprinting" experiments to monitor occupancy of the three AraC sites and measurements of activity of the two promoters. These measurements were made both in the absence of the inducer arabinose and at various times after arabinose addition to growing cells containing the wild-type ara regulatory region or the regulatory region containing various deletions and point mutations. The data lead to the conclusion that two different DNA loops can form in the ara regulatory region. These loops are generated by AraC protein molecules binding to two different DNA sites and binding to each other. One of these loops predominates in the absence of arabinose and plays a major role in repressing activity of one of the promoters. Upon the addition of arabinose the amount of the first loop type, the repression loop, decreases and the amount of a second loop increases. Formation of this second loop precludes the counterproductive formation of the repression loop.

  3. Ribulokinase and transcriptional regulation of arabinose metabolism in Clostridium acetobutylicum.

    PubMed

    Zhang, Lei; Leyn, Semen A; Gu, Yang; Jiang, Weihong; Rodionov, Dmitry A; Yang, Chen

    2012-03-01

    The transcription factor AraR controls utilization of L-arabinose in Bacillus subtilis. In this study, we combined a comparative genomic reconstruction of AraR regulons in nine Clostridium species with detailed experimental characterization of AraR-mediated regulation in Clostridium acetobutylicum. Based on the reconstructed AraR regulons, a novel ribulokinase, AraK, present in all analyzed Clostridium species was identified, which was a nonorthologous replacement of previously characterized ribulokinases. The predicted function of the araK gene was confirmed by inactivation of the araK gene in C. acetobutylicum and biochemical assays using purified recombinant AraK. In addition to the genes involved in arabinose utilization and arabinoside degradation, extension of the AraR regulon to the pentose phosphate pathway genes in several Clostridium species was revealed. The predicted AraR-binding sites in the C. acetobutylicum genome and the negative effect of L-arabinose on DNA-regulator complex formation were verified by in vitro binding assays. The predicted AraR-controlled genes in C. acetobutylicum were experimentally validated by testing gene expression patterns in both wild-type and araR-inactivated mutant strains during growth in the absence or presence of L-arabinose.

  4. Chlorogenic acid-arabinose hybrid domains in coffee melanoidins: Evidences from a model system.

    PubMed

    Moreira, Ana S P; Coimbra, Manuel A; Nunes, Fernando M; Passos, Cláudia P; Santos, Sónia A O; Silvestre, Armando J D; Silva, André M N; Rangel, Maria; Domingues, M Rosário M

    2015-10-15

    Arabinose from arabinogalactan side chains was hypothesized as a possible binding site for chlorogenic acids in coffee melanoidins. To investigate this hypothesis, a mixture of 5-O-caffeoylquinic acid (5-CQA), the most abundant chlorogenic acid in green coffee beans, and (α1 → 5)-L-arabinotriose, structurally related to arabinogalactan side chains, was submitted to dry thermal treatments. The compounds formed during thermal processing were identified by electrospray ionization mass spectrometry (ESI-MS) and characterized by tandem MS (ESI-MS(n)). Compounds composed by one or two CQAs covalently linked with pentose (Pent) residues (1-12) were identified, along with compounds bearing a sugar moiety but composed exclusively by the quinic or caffeic acid moiety of CQAs. The presence of isomers was demonstrated by liquid chromatography online coupled to ESI-MS and ESI-MS(n). Pent1-2CQA were identified in coffee samples. These results give evidence for a diversity of chlorogenic acid-arabinose hybrids formed during roasting, opening new perspectives for their identification in melanoidin structures.

  5. The role of arabinokinase in arabinose toxicity in plants.

    PubMed

    Behmüller, Robert; Kavkova, Eva; Düh, Stefanie; Huber, Christian G; Tenhaken, Raimund

    2016-08-01

    Plant cell wall polymers are synthesized by glycosyltransferases using nucleotide sugars as substrates. Most UDP-sugars are synthesized from UDP-glucose via de novo pathways but salvage pathways work in parallel to recycle sugars, which have been released during cell wall polymer and glycoprotein turnover. Here we report on the cloning and biochemical analysis of two arabinokinases in Arabidopsis. Arabinokinase is a 100 kDa protein located in the cytosol with a putative N-terminal glycosyltransferase domain and a C-terminal sugar-1-kinase domain. This unique structure is highly conserved in the plant kingdom. Arabinokinase has a high affinity for l-arabinose, which is the only sugar substrate of this GHMP (galactose; homoserine; mevalonate; phosphomevalonate) kinase. Plants that were knocked-out for arabinokinase and the previously described ara1-1 mutant were characterized. The ARA1-1 mutant form of the enzyme carries a point mutation in an α-helix. The mutation is close to the substrate binding site and changes the Km value for arabinose from 80 μm in the wild type to 17 000 μm in ARA1-1. The previous arabinose toxicity explanation is challenged by knockout plants in arabinokinase that accumulate higher levels of arabinose but do not show signs of arabinose toxicity. Analysis of marker genes from sugar signalling pathways (SnRK1 and Tor) suggest that ara1-1 misinterprets its carbon energy status. Although glucose is present in ara1-1 similar to wild type levels, it constitutively changes gene expression as typically found in wild type plants only under starvation conditions. Furthermore, ara1-1 shows increased expression of marker genes for programmed cell death as found in other lesion mimic mutants.

  6. Sinorhizobium meliloti pSymB carries genes necessary for arabinose transport and catabolism.

    PubMed

    Poysti, Nathan J; Loewen, Erin D M; Wang, Zexi; Oresnik, Ivan J

    2007-03-01

    Arabinose is a known component of plant cell walls and is found in the rhizosphere. In this work, a previously undeleted region of the megaplasmid pSymB was identified as encoding genes necessary for arabinose catabolism, by Tn5-B20 random mutagenesis and subsequent complementation. Transcription of this region was measured by beta-galactosidase assays of Tn5-B20 fusions, and shown to be strongly inducible by arabinose, and moderately so by galactose and seed exudate. Accumulation of [(3)H]arabinose in mutants and wild-type was measured, and the results suggested that this operon is necessary for arabinose transport. Although catabolite repression of the arabinose genes by succinate or glucose was not detected at the level of transcription, both glucose and galactose were found to inhibit accumulation of arabinose when present in excess. To determine if glucose was also taken up by the arabinose transport proteins, [(14)C]glucose uptake rates were measured in wild-type and arabinose mutant strains. No differences in glucose uptake rates were detected between wild-type and arabinose catabolism mutant strains, indicating that excess glucose did not compete with arabinose for transport by the same system. Arabinose mutants were tested for the ability to form nitrogen-fixing nodules on alfalfa, and to compete with the wild-type for nodule occupancy. Strains unable to utilize arabinose did not display any symbiotic defects, and were not found to be less competitive than wild-type for nodule occupancy in co-inoculation experiments. Moreover, the results suggest that other loci are required for arabinose catabolism, including a gene encoding arabinose dehydrogenase.

  7. Management of antibiotic residues from agricultural sources: use of composting to reduce chlortetracycline residues in beef manure from treated animals.

    PubMed

    Arikan, Osman A; Mulbry, Walter; Rice, Clifford

    2009-05-30

    Chlortetracycline (CTC) is one of only ten antibiotics licensed in the U.S.A. for use as growth promoters for livestock. The widespread use and persistence of CTC may contribute in development of antibiotic-resistant bacteria. The objective of this study was to determine the effect of composting on the fate of CTC residues found in manure from medicated animals. The effect of CTC residues on composting was also investigated. Five beef calves were medicated for 5 days with 22 mg/kg/day of CTC. Manure samples collected from calves prior to and after medication were mixed with straw and woodchips, and aliquots of the subsequent mixtures were treated in laboratory composters for 30 days. In addition, aliquots of the CTC-containing mixture were incubated at 25 degrees C or sterilized followed by incubation at 25 degrees C and 55 degrees C (composting temperature). The presence of CTC did not appear to affect the composting process. Concentrations of CTC/ECTC (the summed concentrations of CTC and its epimer ECTC) in the composted mixture (CM) and sterilized mixture incubated at 55 degrees C (SM55) decreased 99% and 98% (from 113 microg/g dry weight (DW) to 0.7 microg/g DW and 2.0 microg/g DW), respectively, in 30 days. In contrast, levels of CTC/ECTC in room temperature incubated (RTIM) and sterilized mixture incubated at 25 degrees C (SM25) decreased 49% and 40% (to 58 microg/g DW and 68 microg/g DW), respectively, after 30 days. Concentrations of the CTC metabolite, iso-chlortetracycline (ICTC), in CM and SM55 decreased more than 99% (from 12 microg/g DW to below quantitation limit of 0.3 microg/g DW) in 30 days. ICTC levels in RTIM and SM25 decreased 80% (to 4 microg/g DW) in 30 days. These results confirm and extend those from previous studies that show the increased loss of extractable CTC residues with increased time and incubation temperature. In addition, our results using sterile and non-sterile samples suggest that the decrease in concentrations of extractable

  8. Comparison between liquid and solid acids catalysts on reducing sugars conversion from furfural residues via pretreatments.

    PubMed

    Lin, Keying; Ma, Baojun; Sun, Yuan; Liu, Wanyi

    2014-09-01

    Liquid sulphuric acid is adopted and compared with carbon-based sulfonated solid acids (coal tar-based and active carbon-based) for furfural residues conversion into reducing sugars. The optimum hydrolysis conditions of liquid acid are at 4% of sulphuric acid, 25:1 of liquid and solid ratio, 175°C of reaction temperature and 120 min of reaction time. The reducing sugar yields are reached over 60% on liquid acid via NaOH/H2O2, NaOH/microwave and NaOH/ultrasonic pretreatments, whereas only over 30% on solid acids. The TOFs (turnover number frequency) via NaOH/H2O2 pretreatments are 0.093, 0.020 and 0.023 h(-1) for liquid sulphuric acid, coal tar-based and active carbon-based solid acids catalysts, respectively. Considering the efficiency, cost and environment factors, the liquid and solid acids have their own advantages of potential commercial application values.

  9. Cloning, Expression, and Characterization of a Novel L-Arabinose Isomerase from the Psychrotolerant Bacterium Pseudoalteromonas haloplanktis.

    PubMed

    Xu, Wei; Fan, Chen; Zhang, Tao; Jiang, Bo; Mu, Wanmeng

    2016-11-01

    L-Arabinose isomerase (L-AI, EC 5.3.1.4) catalyzes the isomerization between L-arabinose and L-ribulose, and most of the reported ones can also catalyze D-galactose to D-tagatose, except Bacillus subtilis L-AI. In this article, the L-AI from the psychrotolerant bacterium Pseudoalteromonas haloplanktis ATCC 14393 was characterized. The enzyme showed no substrate specificity toward D-galactose, which was similar to B. subtilis L-AI but distinguished from other reported L-AIs. The araA gene encoding the P. haloplanktis L-AI was cloned and overexpressed in E. coli BL21 (DE3). The recombinant enzyme was purified by one-step nickel affinity chromatography . The enzyme displayed the maximal activity at 40 °C and pH 8.0, and showed more than 75 % of maximal activity from pH 7.5-9.0. Metal ion Mn(2+) was required as optimum metal cofactor for activity simulation, but it did not play a significant role in thermostability improvement as reported previously. The Michaelis-Menten constant (K m), turnover number (k cat), and catalytic efficiency (k cat/K m) for substrate L-arabinose were measured to be 111.68 mM, 773.30/min, and 6.92/mM/min, respectively. The molecular docking results showed that the active site residues of P. haloplanktis L-AI could only immobilize L-arabinose and recognized it as substrate for isomerization.

  10. Characterization of a F280N variant of L-arabinose isomerase from Geobacillus thermodenitrificans identified as a D-galactose isomerase.

    PubMed

    Kim, Baek-Joong; Hong, Seung-Hye; Shin, Kyung-Chul; Jo, Ye-Seul; Oh, Deok-Kun

    2014-11-01

    The double-site variant (C450S-N475K) L-arabinose isomerase (L-AI) from Geobacillus thermodenitrificans catalyzes the isomerization of D-galactose to D-tagatose, a functional sweetener. Using a substrate-docking homology model, the residues near to D-galactose O6 were identified as Met186, Phe280, and Ile371. Several variants obtained by site-directed mutagenesis of these three residues were analyzed, and a triple-site (F280N) variant enzyme exhibited the highest activity for D-galactose isomerization. The k cat/K m of the triple-site variant enzyme for D-galactose was 2.1-fold higher than for L-arabinose, whereas the k cat/K m of the double-site variant enzyme for L-arabinose was 43.9-fold higher than for D-galactose. These results suggest that the triple-site variant enzyme is a D-galactose isomerase. The conversion rate of D-galactose to D-tagatose by the triple-site variant enzyme was approximately 3-fold higher than that of the double-site variant enzyme for 30 min. However, the conversion yields of L-arabinose to L-ribulose by the triple-site and double-site variant enzymes were 10.6 and 16.0 % after 20 min, respectively. The triple-site variant enzyme exhibited increased specific activity, turnover number, catalytic efficiency, and conversion rate for D-galactose isomerization compared to the double-site variant enzyme. Therefore, the amino acid at position 280 determines the substrate specificity for D-galactose and L-arabinose, and the triple-site variant enzyme has the potential to produce D-tagatose on an industrial scale.

  11. A Link between Arabinose Utilization and Oxalotrophy in Bradyrhizobium japonicum

    PubMed Central

    Koch, Marion; Delmotte, Nathanaël; Ahrens, Christian H.; Omasits, Ulrich; Schneider, Kathrin; Danza, Francesco; Padhi, Barnali; Murset, Valérie; Braissant, Olivier; Vorholt, Julia A.; Hennecke, Hauke

    2014-01-01

    Rhizobia have a versatile catabolism that allows them to compete successfully with other microorganisms for nutrients in the soil and in the rhizosphere of their respective host plants. In this study, Bradyrhizobium japonicum USDA 110 was found to be able to utilize oxalate as the sole carbon source. A proteome analysis of cells grown in minimal medium containing arabinose suggested that oxalate oxidation extends the arabinose degradation branch via glycolaldehyde. A mutant of the key pathway genes oxc (for oxalyl-coenzyme A decarboxylase) and frc (for formyl-coenzyme A transferase) was constructed and shown to be (i) impaired in growth on arabinose and (ii) unable to grow on oxalate. Oxalate was detected in roots and, at elevated levels, in root nodules of four different B. japonicum host plants. Mixed-inoculation experiments with wild-type and oxc-frc mutant cells revealed that oxalotrophy might be a beneficial trait of B. japonicum at some stage during legume root nodule colonization. PMID:24463964

  12. Microbial conversion of L-arabinose to xylitol by coexpression of L-arabinose isomerase, D-tagatose 3-epimerase, and L-xylulose reductase in Escherichia coli

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A microbial strain has been developed that can produce xylitol from L-arabinose at a high yield by transforming Escherichia coli with a new xylitol biosynthetic pathway consisting of L-arabinose isomerase, D-tagatose 3-epimerase, and L-xylulose reductase. An E. coli strain that heterologously expre...

  13. Evaluation of aluminosilicate compounds to reduce aflatoxin residues and toxicity to poultry and livestock: a review report.

    PubMed

    Harvey, R B; Kubena, L F; Phillips, T D

    1993-01-01

    The aflatoxins (AFs) are reported to be hepatotoxic, mutagenic, immunosuppressive, and carcinogenic. Methods to prevent, reduce, or remediate AF toxicity and residues in the environment are in great demand. Various AF-detoxification procedures are reviewed with particular emphasis on ammoniation and the use of adsorbent compounds to bind AF. A series of in vivo experiments by the authors are reviewed that evaluated the ability of a specific hydrated sodium calcium aluminosilicate (HSCAS) adsorbent to reduce the toxicity of AF to poultry and livestock and to reduce AF residues in milk. These studies showed that HSCAS forms stable bonds with AF in vitro, and when added to AF-contaminated poultry and livestock feeds, HSCAS is able to protect chickens, swine, and lambs from the deleterious toxic effects of AF and to reduce AF residues in milk of dairy cows and goats. These results indicate that HSCAS, when used in conjunction with other mycotoxin management practices, may prove effective for the preventive management of AF-contaminated feedstuffs in livestock and poultry and may reduce AF residues in the food-chain.

  14. Biofuels from crop residue can reduce soil carbon and increase CO2 emissions

    NASA Astrophysics Data System (ADS)

    Liska, Adam J.; Yang, Haishun; Milner, Maribeth; Goddard, Steve; Blanco-Canqui, Humberto; Pelton, Matthew P.; Fang, Xiao X.; Zhu, Haitao; Suyker, Andrew E.

    2014-05-01

    Removal of corn residue for biofuels can decrease soil organic carbon (SOC; refs , ) and increase CO2 emissions because residue C in biofuels is oxidized to CO2 at a faster rate than when added to soil. Net CO2 emissions from residue removal are not adequately characterized in biofuel life cycle assessment (LCA; refs , , ). Here we used a model to estimate CO2 emissions from corn residue removal across the US Corn Belt at 580 million geospatial cells. To test the SOC model, we compared estimated daily CO2 emissions from corn residue and soil with CO2 emissions measured using eddy covariance, with 12% average error over nine years. The model estimated residue removal of 6 Mg per ha-1 yr-1 over five to ten years could decrease regional net SOC by an average of 0.47-0.66 Mg C ha-1 yr-1. These emissions add an average of 50-70 g CO2 per megajoule of biofuel (range 30-90) and are insensitive to the fraction of residue removed. Unless lost C is replaced, life cycle emissions will probably exceed the US legislative mandate of 60% reduction in greenhouse gas (GHG) emissions compared with gasoline.

  15. Tight regulation, modulation, and high-level expression by vectors containing the arabinose PBAD promoter.

    PubMed

    Guzman, L M; Belin, D; Carson, M J; Beckwith, J

    1995-07-01

    We have constructed a series of plasmid vectors (pBAD vectors) containing the PBAD promoter of the araBAD (arabinose) operon and the gene encoding the positive and negative regulator of this promoter, araC. Using the phoA gene and phoA fusions to monitor expression in these vectors, we show that the ratio of induction/repression can be 1,200-fold, compared with 50-fold for PTAC-based vectors. phoA expression can be modulated over a wide range of inducer (arabinose) concentrations and reduced to extremely low levels by the presence of glucose, which represses expression. Also, the kinetics of induction and repression are very rapid and significantly affected by the ara allele in the host strain. Thus, the use of this system which can be efficiently and rapidly turned on and off allows the study of important aspects of bacterial physiology in a very simple manner and without changes of temperature. We have exploited the tight regulation of the PBAD promoter to study the phenotypes of null mutations of essential genes and explored the use of pBAD vectors as an expression system.

  16. Regulation of expression of the arabinose and glucose transporter genes in the thermophilic archaeon Sulfolobus solfataricus.

    PubMed

    Lubelska, Joanna M; Jonuscheit, Melanie; Schleper, Christa; Albers, Sonja-Verena; Driessen, Arnold J M

    2006-10-01

    Sugar uptake in Sulfolobus solfataricus, a thermoacidophilic archaeon, occurs through high-affinity binding of protein-dependent ABC transporters. We have investigated the expression patterns of two sugar transport operons, that is, the glucose and arabinose transporters. Analysis of the araS promoter activity, and the mRNA and protein levels in S. solfataricus cells grown on different carbon sources showed that expression of the arabinose transporter gene cluster is highly regulated and dependent on the presence of arabinose in the medium. Glucose in the growth medium repressed the expression of the arabinose transport genes. By means of primer extension, the transcriptional start site for the arabinose operon was mapped. Interestingly, expression of the arabinose transporter is down-regulated by addition of a selective set of amino acids to the medium. Expression of the glucose transporter genes appeared constitutive. These data confirm the earlier observation of a catabolite repression-like system in S. solfataricus.

  17. Mathematical modeling of the low and high affinity arabinose transport systems in Escherichia coli.

    PubMed

    Yildirim, Necmettin

    2012-04-01

    A mathematical model was developed for the low and high affinity arabinose transport systems in E. coli. The model is a system of three ordinary differential equations and takes the dynamics of mRNAs for the araE and araFGH proteins and the internal arabinose into account. Special attention was paid to estimate the model parameters from the literature. Our analysis and simulations suggest that the high affinity transport system helps the low affinity transport system to respond to high concentration of extracellular arabinose faster, whereas the high affinity transport system responds to a small amount of extracellular arabinose. Steady state analysis of the model also predicts that there is a regime for the extracellular concentration of arabinose where the arabinose system can show bistable behavior.

  18. Identification and functional analysis of the gene cluster for L-arabinose utilization in Corynebacterium glutamicum.

    PubMed

    Kawaguchi, Hideo; Sasaki, Miho; Vertès, Alain A; Inui, Masayuki; Yukawa, Hideaki

    2009-06-01

    Corynebacterium glutamicum ATCC 31831 grew on l-arabinose as the sole carbon source at a specific growth rate that was twice that on d-glucose. The gene cluster responsible for l-arabinose utilization comprised a six-cistron transcriptional unit with a total length of 7.8 kb. Three l-arabinose-catabolizing genes, araA (encoding l-arabinose isomerase), araB (l-ribulokinase), and araD (l-ribulose-5-phosphate 4-epimerase), comprised the araBDA operon, upstream of which three other genes, araR (LacI-type transcriptional regulator), araE (l-arabinose transporter), and galM (putative aldose 1-epimerase), were present in the opposite direction. Inactivation of the araA, araB, or araD gene eliminated growth on l-arabinose, and each of the gene products was functionally homologous to its Escherichia coli counterpart. Moreover, compared to the wild-type strain, an araE disruptant exhibited a >80% decrease in the growth rate at a lower concentration of l-arabinose (3.6 g liter(-1)) but not at a higher concentration of l-arabinose (40 g liter(-1)). The expression of the araBDA operon and the araE gene was l-arabinose inducible and negatively regulated by the transcriptional regulator AraR. Disruption of araR eliminated the repression in the absence of l-arabinose. Expression of the regulon was not repressed by d-glucose, and simultaneous utilization of l-arabinose and d-glucose was observed in aerobically growing wild-type and araR deletion mutant cells. The regulatory mechanism of the l-arabinose regulon is, therefore, distinct from the carbon catabolite repression mechanism in other bacteria.

  19. Single cell kinetics of phenotypic switching in the arabinose utilization system of E. coli.

    PubMed

    Fritz, Georg; Megerle, Judith A; Westermayer, Sonja A; Brick, Delia; Heermann, Ralf; Jung, Kirsten; Rädler, Joachim O; Gerland, Ulrich

    2014-01-01

    Inducible switching between phenotypes is a common strategy of bacteria to adapt to fluctuating environments. Here, we analyze the switching kinetics of a paradigmatic inducible system, the arabinose utilization system in E. coli. Using time-lapse fluorescence microscopy of microcolonies in a microfluidic chamber, which permits sudden up- and down-shifts in the inducer arabinose, we characterize the single-cell gene expression dynamics of the araBAD operon responsible for arabinose degradation. While there is significant, inducer-dependent cell-to-cell variation in the timing of the on-switching, the off-switching triggered by sudden removal of arabinose is homogeneous and rapid. We find that rapid off-switching does not depend on internal arabinose degradation. Because the system is regulated via the internal arabinose level sensed by AraC, internal arabinose must be rapidly depleted by leakage or export from the cell, or by degradation via a non-canonical pathway. We explored whether the poorly characterized membrane protein AraJ, which is part of the arabinose regulon and has been annotated as a possible arabinose efflux protein, is responsible for rapid depletion. However, we find that AraJ is not essential for rapid switching to the off-state. We develop a mathematical model for the arabinose system, which quantitatively describes both the heterogeneous on-switching and the homogeneous off-switching. The model also predicts that mutations which disrupt the positive feedback of internal arabinose on the production of arabinose uptake proteins change the heterogeneous on-switching behavior into a homogeneous, graded response. We construct such a mutant and confirm the graded response experimentally. Taken together, our results indicate that the physiological switching behavior of this sugar utilization system is asymmetric, such that off-switching is always rapid and homogeneous, while on-switching is slow and heterogeneously timed at sub-saturating inducer

  20. [Effect of reduced N application on soil N residue and N loss in maize-soybean relay strip intercropping system].

    PubMed

    Liu, Xiao-Ming; Yong, Tai-Wen; Liu, Wen-Yu; Su, Ben-Ying; Song, Chun; Yang, Feng; Wang, Xiao-Chun; Yang, Wen-Yu

    2014-08-01

    A field experiment was conducted in 2012, including three planting pattern (maize-soybean relay strip intercropping, mono-cultured maize and soybean) and three nitrogen application level [0 kg N x hm(-2), 180 kg N x hm(-2) (reduced N) and 240 kg N x hm(-2) (normal N)]. Fields were assigned to different treatments in a randomized block design with three replicates. The objective of this work was to analyze the effects of planting patterns and nitrogen application rates on plant N uptake, soil N residue and N loss. After fertilization applications, NH4(+)-N and NO3(-)-N levels increased in the soil of intercropped maize but decreased in the soil of intercropped soybean. Compared with mono-crops, the soil N residue and loss of intercropped soybean were reduced, while those of intercropped maize were increased and decreased, respectively. With the reduced rate of N application, N residue rate, N loss rate and ammonia volatilization loss rate of the maize-soybean intercropping relay strip system were decreased by 17.7%, 21.5% and 0.4% compared to mono-cultured maize, but increased by 2.0%, 19.8% and 0.1% compared to mono-cultured soybean, respectively. Likewise, the reduced N application resulted in reductions in N residue, N loss, and the N loss via ammonia volatilization in the maize-soybean relay strip intercropping system compared with the conventional rate of N application adopted by local farmers, and the N residue rate, N loss rate and ammonia volatilization loss rate reduced by 12.0%, 15.4% and 1.2%, respectively.

  1. High-affinity L-arabinose transport operon. Nucleotide sequence and analysis of gene products.

    PubMed

    Scripture, J B; Voelker, C; Miller, S; O'Donnell, R T; Polgar, L; Rade, J; Horazdovsky, B F; Hogg, R W

    1987-09-05

    The nucleotide sequence of the "high-affinity" L-arabinose transport operon has been determined 3' from the regulatory region and found to contain three open reading frames designated araF, araG and araH. The first gene 3' to the regulatory region, araF, encodes the 23-residue signal peptide and the 306-residue mature form of the L-arabinose binding protein (33,200 Mr). The binding protein, which has been described elsewhere, is hydrophilic, soluble and found in the periplasm of Escherichia coli. This gene is followed by an intragenic space of 72 nucleotides, which contains a region of dyad symmetry 23 nucleotides long capable of forming an 11-member stem-loop. The second gene, designated araG, contains an open reading frame capable of encoding an equally hydrophilic protein containing 504 residues (55,000 Mr). Following a 14-nucleotide spacer, which does not appear to have any secondary structure, the third open reading frame, herein designated araH, is capable of encoding a hydrophobic protein containing 329 residues (34,000 Mr) that can only be envisioned as having an integral membrane location. 3' to araH there is a T-rich region containing a 24-nucleotide area of dyad symmetry centered 55 nucleotides from the termination codon. Analysis of the derived primary sequences of the araG and araH products indicates the nature and potential features of these components. The araG protein was found to possess internal homology between its amino and carboxyl-terminal halves, suggesting a common origin. The araG gene product has been shown to be homologous to the rbsA gene product, the hisP product, the ptsB product and the malK product, all of which presumably play similar roles in their respective transport systems. Putative ATP binding sites are observed within the regions of homology. The araH gene product has been shown to be homologous to the rbsC gene product, which is the first observed homology between two purported membrane proteins.

  2. Negative auto-regulation increases the input dynamic-range of the arabinose system of Escherichia coli

    PubMed Central

    2011-01-01

    Background Gene regulation networks are made of recurring regulatory patterns, called network motifs. One of the most common network motifs is negative auto-regulation, in which a transcription factor represses its own production. Negative auto-regulation has several potential functions: it can shorten the response time (time to reach halfway to steady-state), stabilize expression against noise, and linearize the gene's input-output response curve. This latter function of negative auto-regulation, which increases the range of input signals over which downstream genes respond, has been studied by theory and synthetic gene circuits. Here we ask whether negative auto-regulation preserves this function also in the context of a natural system, where it is embedded within many additional interactions. To address this, we studied the negative auto-regulation motif in the arabinose utilization system of Escherichia coli, in which negative auto-regulation is part of a complex regulatory network. Results We find that when negative auto-regulation is disrupted by placing the regulator araC under constitutive expression, the input dynamic range of the arabinose system is reduced by 10-fold. The apparent Hill coefficient of the induction curve changes from about n = 1 with negative auto-regulation, to about n = 2 when it is disrupted. We present a mathematical model that describes how negative auto-regulation can increase input dynamic-range, by coupling the transcription factor protein level to the input signal. Conclusions Here we demonstrate that the negative auto-regulation motif in the native arabinose system of Escherichia coli increases the range of arabinose signals over which the system can respond. In this way, negative auto-regulation may help to increase the input dynamic-range while maintaining the specificity of cooperative regulatory systems. This function may contribute to explaining the common occurrence of negative auto-regulation in biological systems. PMID

  3. Investigating a method for reducing residual switch costs in cued task switching.

    PubMed

    Schneider, Darryl W

    2016-07-01

    Residual switch costs in cued task switching are performance decrements that occur despite a long cue-target interval (CTI) to prepare for a task switch. Verbruggen, Liefooghe, Vandierendonck, and Demanet (Journal of Experimental Psychology: Learning, Memory, and Cognition, 33; 342-356, 2007) showed that briefly presenting the cue during the CTI and leaving it absent after target onset yielded smaller residual switch costs than those obtained when the cue was available for the full CTI and remained present after target onset. The potential effects of cue availability during the CTI (full or partial) and cue status after target onset (present or absent) on residual switch costs were investigated in the present study. In Experiments 1 and 2, cue status was manipulated while holding cue availability constant. In Experiments 3 and 4, cue status and cue availability were manipulated factorially. Residual switch costs were obtained, but they were not modulated consistently by cue status or cue availability across experiments. In Experiment 5, a direct replication of one of Verbruggen and colleagues' experiments yielded divergent results. Implications for understanding task switching are discussed.

  4. USING REDUCING AGENTS TO ELIMINATE CHLORINE DIOXIDE AND CHLORITE ION RESIDUALS IN DRINKING WATER

    EPA Science Inventory

    In an effort to determine the viability of various disinfection alternatives, the Evansville, Ind. Water and Sewer Utility is engaged in a pilot-plant investigation to compare chlorine dioxide and ozone pretreatment. As a result of increased speculation that the total residual c...

  5. RCS pressure under reduced inventory conditions following a loss of residual heat removal

    SciTech Connect

    Palmrose, D.E.; Hughes, E.D.; Johnsen, G.W.

    1992-08-01

    The thermal-hydraulic response of a closed-reactor coolant system to loss of residual heat removal (RHR) cooling is investigated. The processes examined include: core coolant boiling and steam generator reflux condensation, pressure increase on the primary side, heat transfer mechanisms on the steam generator primary and secondary sides, and effects of noncondensible gas on heat transfer processes.

  6. RCS pressure under reduced inventory conditions following a loss of residual heat removal

    SciTech Connect

    Palmrose, D.E.; Hughes, E.D.; Johnsen, G.W.

    1992-01-01

    The thermal-hydraulic response of a closed-reactor coolant system to loss of residual heat removal (RHR) cooling is investigated. The processes examined include: core coolant boiling and steam generator reflux condensation, pressure increase on the primary side, heat transfer mechanisms on the steam generator primary and secondary sides, and effects of noncondensible gas on heat transfer processes.

  7. Ultra-fast annealing to reduce the residual stress in ultra-thin chips using flash light

    NASA Astrophysics Data System (ADS)

    Jeon, Eun-Beom; Park, Junhong; Kim, Hak-Sung

    2014-04-01

    The continuing trend of miniaturization in electronic equipment includes demands for thinner and smaller semiconductor devices with higher performance. To ensure the reliability of electronic devices and to enable high-throughput packaging processes, the mechanical properties of ultra-thin chips need to be accurately understood. One important consideration is the residual stress generated during wafer thinning due to the shear force between the grinding wheel and polish pad; this stress can degrade the fracture strength of ultra-thin devices. To reduce this residual stress, we developed a flash light irradiation annealing technique, including optimization of the irradiation conditions of flash light energy, pulse number and pulse duration. The distributions of residual stresses within ultra-thin flash memory chips before and after the annealing were measured using Raman spectroscopy, and their fracture strength was measured using a ball-on-ring test. Also, transmission electron microscopy (TEM) analysis and beam transfer function tests were performed to investigate the changes in mechanical properties and changes to the silicon lattice effected by the annealing. The ultra-fast flash light annealing was found to reduce the residual stress of ultra-thin chips by 50%, thereby improving their fracture strength by 20% compared to unannealed chips.

  8. Microbial production of xylitol from L-arabinose by metabolically engineered Escherichia coli.

    PubMed

    Sakakibara, Yoshikiyo; Saha, Badal C; Taylor, Paul

    2009-05-01

    An Escherichia coli strain, ZUC99(pATX210), which can produce xylitol from L-arabinose at a high yield, has been created by introducing a new bioconversion pathway into the cells. This pathway consists of three enzymes: L-arabinose isomerase (which converts L-arabinose to L-ribulose), D-psicose 3-epimerase (which converts L-ribulose to L-xylulose), and L-xylulose reductase (which converts L-xylulose to xylitol). The genes encoding these enzymes were cloned behind the araBAD promoter in tandem so that they were polycistronically transcribed from the single promoter, like an operon. Expression of the recombinant enzymes in the active form was successfully achieved in the presence of L-arabinose. A xylitol production profile of the recombinant strain was evaluated by shake-flask fermentation. ZUC99(pATX210) produced 2.6 g/l xylitol using 4.2 g/l L-arabinose with a xylitol yield of 0.62 g/g L-arabinose in 36 h. It was determined that utilization of glycerol as a co-substrate significantly improved xylitol production and yield. In the presence of 11.8 g/l glycerol, ZUC99(pATX210) produced 9.7 g/l xylitol from 10.5 g/l L-arabinose with a xylitol yield of 0.92 g/g L-arabinose in 36 h. ZUC99(pATX210) also exhibited efficient conversion in fermentor experiments with 1 l medium containing L-arabinose and glycerol. The strain produced 14.5 g/l xylitol from 15.2 g/l L-arabinose with a xylitol yield of 0.95 g/g L-arabinose in 30 h.

  9. Epistatic Interactions in the Arabinose Cis-Regulatory Element.

    PubMed

    Lagator, Mato; Igler, Claudia; Moreno, Anaísa B; Guet, Călin C; Bollback, Jonathan P

    2016-03-01

    Changes in gene expression are an important mode of evolution; however, the proximate mechanism of these changes is poorly understood. In particular, little is known about the effects of mutations within cis binding sites for transcription factors, or the nature of epistatic interactions between these mutations. Here, we tested the effects of single and double mutants in two cis binding sites involved in the transcriptional regulation of the Escherichia coli araBAD operon, a component of arabinose metabolism, using a synthetic system. This system decouples transcriptional control from any posttranslational effects on fitness, allowing a precise estimate of the effect of single and double mutations, and hence epistasis, on gene expression. We found that epistatic interactions between mutations in the araBAD cis-regulatory element are common, and that the predominant form of epistasis is negative. The magnitude of the interactions depended on whether the mutations are located in the same or in different operator sites. Importantly, these epistatic interactions were dependent on the presence of arabinose, a native inducer of the araBAD operon in vivo, with some interactions changing in sign (e.g., from negative to positive) in its presence. This study thus reveals that mutations in even relatively simple cis-regulatory elements interact in complex ways such that selection on the level of gene expression in one environment might perturb regulation in the other environment in an unpredictable and uncorrelated manner.

  10. Efficiency of light-emitting diode and halogen units in reducing residual monomers

    PubMed Central

    de Assis Ribeiro Carvalho, Felipe; Almeida, Rhita C.; Almeida, Marco Antonio; Cevidanes, Lucia H. S.; Leite, Marcia C. Amorim M.

    2011-01-01

    Introduction In this in-vitro study, we aimed to compare the residual monomers in composites beneath brackets bonded to enamel, using a light-emitting diode (LED) or a halogen unit, and to compare the residual monomers in the central to the peripheral areas of the composite. Methods Twenty bovine teeth preserved in 0.1% thymol were used in this study. Ten teeth were used to standardize the thickness of the composite film, since different thicknesses would cause different absorbance of light. Brackets were bonded to 10 bovine incisors, with the halogen light (n = 5) and the LED (n = 5). The brackets were debonded, and the remaining composite on the enamel surface was sectioned in 2 regions: peripheral (0.8 mm) and central, resulting in 2 subgroups per group: central halogen (n = 5), peripheral halogen (n = 5), central LED (n = 5), and peripheral LED (n = 5). The spectrometric analysis in the infrared region was used to measure the free monomers with the attenuated total reflectance method. Results Normal distribution was tested by using the Kolmogorov-Smirnov test. Data were compared by 2-way analysis of variance (ANOVA) at P <0.05. The LED group showed fewer residual monomers than did the halogen group (P = 0.014). No differences were found among the regions (P = 0.354), and there were no interactions between light type and region (P = 0.368). Conclusions LED leaves less residual monomer than does the halogen light, even with half of the irradiation time; there were no differences between the central and peripheral regions, and no interaction between light type and region. PMID:21055603

  11. Engineering of Saccharomyces cerevisiae for efficient anaerobic alcoholic fermentation of L-arabinose.

    PubMed

    Wisselink, H Wouter; Toirkens, Maurice J; del Rosario Franco Berriel, M; Winkler, Aaron A; van Dijken, Johannes P; Pronk, Jack T; van Maris, Antonius J A

    2007-08-01

    For cost-effective and efficient ethanol production from lignocellulosic fractions of plant biomass, the conversion of not only major constituents, such as glucose and xylose, but also less predominant sugars, such as l-arabinose, is required. Wild-type strains of Saccharomyces cerevisiae, the organism used in industrial ethanol production, cannot ferment xylose and arabinose. Although metabolic and evolutionary engineering has enabled the efficient alcoholic fermentation of xylose under anaerobic conditions, the conversion of l-arabinose into ethanol by engineered S. cerevisiae strains has previously been demonstrated only under oxygen-limited conditions. This study reports the first case of fast and efficient anaerobic alcoholic fermentation of l-arabinose by an engineered S. cerevisiae strain. This fermentation was achieved by combining the expression of the structural genes for the l-arabinose utilization pathway of Lactobacillus plantarum, the overexpression of the S. cerevisiae genes encoding the enzymes of the nonoxidative pentose phosphate pathway, and extensive evolutionary engineering. The resulting S. cerevisiae strain exhibited high rates of arabinose consumption (0.70 g h(-1) g [dry weight](-1)) and ethanol production (0.29 g h(-1) g [dry weight](-1)) and a high ethanol yield (0.43 g g(-1)) during anaerobic growth on l-arabinose as the sole carbon source. In addition, efficient ethanol production from sugar mixtures containing glucose and arabinose, which is crucial for application in industrial ethanol production, was achieved.

  12. L-ribose production from L-arabinose by using purified L-arabinose isomerase and mannose-6-phosphate isomerase from Geobacillus thermodenitrificans.

    PubMed

    Yeom, Soo-Jin; Kim, Nam-Hee; Park, Chang-Su; Oh, Deok-Kun

    2009-11-01

    Two enzymes, L-arabinose isomerase and mannose-6-phosphate isomerase, from Geobacillus thermodenitrificans produced 118 g/liter L-ribose from 500 g/liter L-arabinose at pH 7.0, 70 degrees C, and 1 mM Co(2+) for 3 h, with a conversion yield of 23.6% and a volumetric productivity of 39.3 g liter(-1) h(-1).

  13. Regulation of the Escherichia coli L-arabinose operon studied by gel electrophoresis DNA binding assay.

    PubMed

    Hendrickson, W; Schleif, R F

    1984-09-25

    DNA binding properties of the proteins required for induction of the Escherichia coli L-arabinose operon were measured using a polyacrylamide gel electrophoresis assay. The mechanisms of induction and repression were studied by observing the multiple interactions of RNA polymerase, cyclic AMP receptor protein and araC protein with short DNA fragments containing either the araC or araBAD promoter regions. These studies show that binding of araC protein to the operator site, araO1, directly blocks RNA polymerase binding at the araC promoter, pC. We find that cyclic AMP receptor protein and araC protein do not bind co-operatively at their respective sites to linear DNA fragments containing the pBAD promoter. Nevertheless, both these positive effectors must be present on the DNA to stimulate binding of RNA polymerase. Additionally, binding of the proteins to the DNA is not sufficient; araC protein must also be in the inducing state, for RNA polymerase to bind. Equilibrium binding constraints and kinetics were determined for araC protein binding to the araI and the araO1 sites. In the presence of inducer, L-arabinose, araC protein binds with equal affinity to DNA fragments containing either of these sites. In the presence of anti-inducer, D-fucose, the affinity for both sites is reduced 40-fold. The apparent equilibrium binding constants for both states of the protein vary in parallel with the buffer salt concentration. This result suggests that the inducing and repressing forms of araC protein displace a similar number of cations upon binding DNA.

  14. Galacturonic acid inhibits the growth of Saccharomyces cerevisiae on galactose, xylose, and arabinose.

    PubMed

    Huisjes, Eline H; de Hulster, Erik; van Dam, Jan C; Pronk, Jack T; van Maris, Antonius J A

    2012-08-01

    The efficient fermentation of mixed substrates is essential for the microbial conversion of second-generation feedstocks, including pectin-rich waste streams such as citrus peel and sugar beet pulp. Galacturonic acid is a major constituent of hydrolysates of these pectin-rich materials. The yeast Saccharomyces cerevisiae, the main producer of bioethanol, cannot use this sugar acid. The impact of galacturonic acid on alcoholic fermentation by S. cerevisiae was investigated with anaerobic batch cultures grown on mixtures of glucose and galactose at various galacturonic acid concentrations and on a mixture of glucose, xylose, and arabinose. In cultures grown at pH 5.0, which is well above the pK(a) value of galacturonic acid (3.51), the addition of 10 g · liter(-1) galacturonic acid did not affect galactose fermentation kinetics and growth. In cultures grown at pH 3.5, the addition of 10 g · liter(-1) galacturonic acid did not significantly affect glucose consumption. However, at this lower pH, galacturonic acid completely inhibited growth on galactose and reduced galactose consumption rates by 87%. Additionally, it was shown that galacturonic acid strongly inhibits the fermentation of xylose and arabinose by the engineered pentose-fermenting S. cerevisiae strain IMS0010. The data indicate that inhibition occurs when nondissociated galacturonic acid is present extracellularly and corroborate the hypothesis that a combination of a decreased substrate uptake rate due to competitive inhibition on Gal2p, an increased energy requirement to maintain cellular homeostasis, and/or an accumulation of galacturonic acid 1-phosphate contributes to the inhibition. The role of galacturonic acid as an inhibitor of sugar fermentation should be considered in the design of yeast fermentation processes based on pectin-rich feedstocks.

  15. Production of D-tagatose, a low caloric sweetener during milk fermentation using L-arabinose isomerase.

    PubMed

    Rhimi, Moez; Chouayekh, Hichem; Gouillouard, Isabelle; Maguin, Emmanuelle; Bejar, Samir

    2011-02-01

    Lactobacillusdelbrueckii subsp. bulgaricus and Streptococcus thermophilus are used for the biotransformation of milk in yoghurt. During milk fermentation, these lactic acid bacteria (LAB) hydrolyze lactose producing a glucose moiety that is further metabolized and a galactose moiety that they are enable to metabolize. We investigated the ability of L. bulgaricus and S. thermophilus strains expressing a heterologous L-arabinose isomerase to convert residual D-galactose to D-tagatose. The Bacillus stearothermophilus US100l-arabinose isomerase (US100l-AI) was expressed in both LAB, using a new shuttle vector where the araA US100 gene is under the control of the strong and constitutive promoter of the L. bulgaricus ATCC 11842 hlbA gene. The production of L-AI by these LAB allowed the bioconversion of D-galactose to D-tagatose during fermentation in laboratory media and milk. We also established that the addition of L-AI to milk also allowed the conversion of D-galactose into D-tagatose during the fermentation process.

  16. Thermal-hydraulic processes involved in loss of residual heat removal during reduced inventory operation

    SciTech Connect

    Fletcher, C.D.; McHugh, P.R.; Naff, S.A.; Johnsen, G.W.

    1991-02-01

    This paper identifies the topics needed to understand pressurized water reactor response to an extended loss of residual heat removal event during refueling and maintenance outages. By identifying the possible plant conditions and cooling methods that would be used for each cooling mode, the controlling thermal-hydraulic processes and phenomena were identified. Controlling processes and phenomena include: gravity drain, core water boil-off, and reflux cooling processes. Important subcategories of the reflux cooling processes include: the initiation of reflux cooling from various plant conditions, the effects of air on reflux cooling, core level depression effects, issues regarding the steam generator secondaries, and the special case of boiler-condenser cooling with once-through steam generators. 25 refs., 6 figs., 1 tab.

  17. Reducing soluble phosphorus in dairy effluents through application of mine drainage residuals

    USGS Publications Warehouse

    Sibrell, Philip L.; Penn, Chad J.; Hedin, Robert S.

    2015-01-01

    Three different dairy manure wastewater effluent samples were amended with mine drainage residuals (MDR) to evaluate the suitability of MDR for sequestration of phosphorus (P). Geochemical modeling of the manure wastewater compositions indicated that partially soluble P-bearing minerals including hydroxyapatite, octacalcium phosphate, and vivianite were all oversaturated in each of the manure wastewater samples. Initial MDR amendment test results indicated that these partially soluble P minerals suspended in the wastewater replenished P in the water phase as it was sorbed by the MDR samples. Further investigations revealed that the MDR samples were effective in decreasing soluble P when the amended manure was tested using the water-extractable P procedure. Under these conditions, up to 90 percent of the soluble P in the manure was converted to a sorbed, water-insoluble state. Water contamination and large-scale validation tests of the process were also conducted.

  18. Engineering of an L-arabinose metabolic pathway in Rhodococcus jostii RHA1 for biofuel production.

    PubMed

    Xiong, Xiaochao; Wang, Xi; Chen, Shulin

    2016-07-01

    The oleaginous bacterium, Rhodococcus jostii RHA1 has attracted considerable attention due to its capability to accumulate significant levels of triacylglycerol as renewable hydrocarbon. To enable the strain to utilize arabinose derived from lignocellulosic biomass, the metabolic pathway of L-arabinose utilization was introduced into R. jostii RHA1 by heterogenous expression of the operon, araBAD from Escherichia coli. The results showed that recombinant bearing araBAD could grow on L-arabinose as the sole carbon source, and additional expression of araFGH encoding the arabinose transporter from E. coli could improve the cell biomass yield from high contents of arabinose. We further increased the content of lipid produced from arabinose in the recombinants from 47.9 to 56.8 % of the cell dry weight (CDW) by overexpression of a gene, atf1 encoding a diglyceride acyltransferase from R. opacus PD630. This work demonstrated the feasibility of producing lipid from arabinose by genetic modification of the rhodococci strain.

  19. Kinetic, structural and molecular docking studies on the inhibition of tyrosinase induced by arabinose.

    PubMed

    Hu, Wei-Jiang; Yan, Li; Park, Daeui; Jeong, Hyoung Oh; Chung, Hae Young; Yang, Jun-Mo; Ye, Zhuo Ming; Qian, Guo-Ying

    2012-04-01

    Tyrosinase plays a central role in biological pigment formation, and hence knowledge of tyrosinase catalytic mechanisms and regulation may have medical, cosmetic, and agricultural applications. We found in this study that arabinose significantly inhibited tyrosinase, and this was accompanied by conformational changes in enzyme structure. Kinetic analysis showed that arabinose-mediated inactivation followed first-order kinetics, and single and multiple classes of rate constants were measured. Arabinose displayed a mixed-type inhibitory mechanism with K(i)=0.22±0.07 mM. Measurements of intrinsic and ANS-binding fluorescence showed that arabinose induced tyrosinase to unfold and expose inner hydrophobic regions. We simulated the docking between tyrosinase and arabinose (binding energies were -26.28 kcal/mol for Dock6.3 and -2.02 kcal/mol for AutoDock4.2) and results suggested that arabinose interacts mostly with His61, Asn260, and Met280. The present strategy of predicting tyrosinase inhibition by simulation of docking by hydroxyl groups may prove useful in screening for potential tyrosinase inhibitors, as shown here for arabinose.

  20. Engineering L-arabinose metabolism in triacylglycerol-producing Rhodococcus opacus for lignocellulosic fuel production.

    PubMed

    Kurosawa, Kazuhiko; Plassmeier, Jens; Kalinowski, Jörn; Rückert, Christian; Sinskey, Anthony J

    2015-07-01

    Advanced biofuels from lignocellulosic biomass have been considered as a potential solution for the issues of energy sustainability and environmental protection. Triacylglycerols (TAGs) are potential precursors for the production of lipid-based liquid biofuels. Rhodococcus opacus PD630 can accumulate large amounts of TAGs when grown under physiological conditions of high carbon and low nitrogen. However, R. opacus PD630 does not utilize the sugar L-arabinose present in lignocellulosic hydrolysates. Here, we report the engineering of R. opacus to produce TAGs on L-arabinose. We constructed a plasmid (pASC8057) harboring araB, araD and araA genes derived from a Streptomyces bacterium, and introduced the genes into R. opacus PD630. One of the engineered strains, MITAE-348, was capable of growing on high concentrations (up to 100 g/L) of L-arabinose. MITAE-348 was grown in a defined medium containing 16 g/L L-arabinose or a mixture of 8 g/L L-arabinose and 8 g/L D-glucose. In a stationary phase occurring 3 days post-inoculation, the strain was able to completely utilize the sugar, and yielded 2.0 g/L for L-arabinose and 2.2 g/L for L-arabinose/D-glucose of TAGs, corresponding to 39.7% or 42.0%, respectively, of the cell dry weight.

  1. Utilization and Transport of L-Arabinose by Non-Saccharomyces Yeasts

    SciTech Connect

    Knoshaug, E. P.; Franden, M. A.; Stambuk, B. U.; Zhang, M.; Singh, A.

    2009-01-01

    L-Arabinose is one of the sugars found in hemicellulose, a major component of plant cell walls. The ability to convert L-arabinose to ethanol would improve the economics of biomass to ethanol fermentations. One of the limitations for L-arabinose fermentation in the current engineered Saccharomyces cerevisiae strains is poor transport of the sugar. To better understand L-arabinose transport and use in yeasts and to identify a source for efficient L-arabinose transporters, 165 non-Saccharomyces yeast strains were studied. These yeast strains were arranged into six groups based on the minimum time required to utilize 20 g/L of L-arabinose. Initial transport rates of L-arabinose were determined for several species and a more comprehensive transport study was done in four selected species. Detailed transport kinetics in Arxula adeninivorans suggested both low and high affinity components while Debaryomyces hansenii var. fabryii, Kluyveromyces marxianus and Pichia guilliermondii possessed a single component, high affinity active transport systems.

  2. Solid-state cultures of Fusarium oxysporum transform aromatic components of olive-mill dry residue and reduce its phytotoxicity.

    PubMed

    Sampedro, Inmaculada; D'Annibale, Alessandro; Ocampo, Juan A; Stazi, Silvia R; García-Romera, Inmaculada

    2007-12-01

    The present study mainly investigated the ability of solid-state cultures of the non-pathogenic Fusarium oxysporum strain BAFC 738 to transform aromatic components to reduce the phytotoxicity in olive-mill dry residue (DOR), the waste from the two-phase manufacturing process. Lignin, hemicellulose, fats and water-soluble extractives contents of DOR colonized by the fungus for 20 weeks were reduced by 16%, 25%, 71% and 13%, respectively, while the cellulose content increased by 25%. In addition, the ethyl acetate-extractable phenolic fraction of the waste was reduced by 65%. However, mass-balance ultra-filtration and size-exclusion chromatography experiments suggested that the apparent removal of that fraction, mainly including 2-(3,4-dihydroxyphenyl)ethyl alcohol and 2-(4-hydroxyphenyl)ethyl alcohol, was due to polymerization. Mn-peroxidase and Mn-independent peroxidase activities were found in F. oxysporum solid-state cultures, while laccase and aryl alcohol oxidase activities were not detected. Tests performed with seedlings of tomato (Lycopersicum esculentum L.), soybean (Glycine maximum Merr.), and alfalfa (Medicago sativa L.) grown on soils containing 6% (w/w) of bioconverted DOR (kg soil)(-1) showed that the waste's phytotoxicity was removed by 20 weeks-old fungal cultures. By contrast, the same material exhibited a high residual toxicity towards lettuce (Lactuca sativa L.).

  3. Integrated Pest Management Practices Reduce Insecticide Applications, Preserve Beneficial Insects, and Decrease Pesticide Residues in Flue-Cured Tobacco Production.

    PubMed

    Slone, Jeremy D; Burrack, Hannah J

    2016-09-22

    Integrated pest management (IPM) recommendations, including scouting and economic thresholds (ETs), are available for North Carolina flue-cured tobacco growers, although ETs for key pests have not been updated in several decades. Moreover, reported IPM adoption rates by flue-cured tobacco growers remain low, at < 40%, according to NC cooperative extension surveys conducted during the last four years. Previous research has suggested that timing insecticide treatments using currently available ETs can reduce the average number of applications to two or fewer per season. We conducted field-scale trials at nine commercial tobacco farms, three in 2104 and six in 2015, to quantify inputs associated with current scouting recommendations, to determine if current ETs were able to reduce insecticide applications as compared to grower standard practices, and to assess the impacts of reduced insecticide applications on end of season yield and pesticide residues. Two fields were identified at each farm and were scouted weekly for insects. One field was only treated with insecticides if pests reached ET (IPM), while the other field was managed per grower discretion (Grower Standard). IPM fields received an average of two fewer insecticide applications without compromising yield. More insecticide applications resulted in higher pesticide residues in cured leaf samples from Grower Standard fields than those from IPM fields. Reductions in insecticides and management intensity also resulted in larger beneficial insect populations in IPM fields.

  4. The L-arabinose-resistance test with Salmonella typhimurium strain SV3 selects forward mutations at several ara genes.

    PubMed

    Pueyo, C; Lopez-Barea, J

    1979-08-01

    A new assay has been described for mutagenicity testing using an L-arabinose-sensitive strain of Salmonella typhimurium. The test strain SV3 and several L-arabinose-resistant mutants selected therefrom are characterized in the present study by 3 different criteria: inhibition of growth by L-arabinose, accumulation of keto-sugars, and activities of the enzymes involved in L-arabinose catabolism. Strain SV3 (ara-531) shows high levels of inducible L-arabinose isomerase (EC 5.3.1.4) and L-ribulokinase (EC 2.7.1.16) activities, but is deficient in L-ribulose-5-phosphate 4-epimerase (EC 5.1.3.4), the enzyme encoded in Escherichia coli by gene D in the araBAD operon. Addition of L-arabinose to SV3 growing in glycerol or casamino acids stops growth. D-Glucose only partially reverses this inhibition. Reversion of the ara-531 mutation restores different levels of epimerase activity and resistance to L-arabinose. However, the great majority of the L-arabinose-resistant mutants do not utilize L-arabinose. The physiological and enzymatic properties of these L-arabinose non-utilizing mutants suggest that L-arabinose resistance is due to forward mutations in at least 3 other genes, araA, araB and araC, blocking steps prior to L-ribulose 5-phosphate accumulation.

  5. Arsenic biotransformation in solid waste residue: comparison of contributions from bacteria with arsenate and iron reducing pathways.

    PubMed

    Tian, Haixia; Shi, Qiantao; Jing, Chuanyong

    2015-02-17

    Arsenic- and iron-reducing bacteria play an important role in regulating As redox transformation and mobility. The motivation of this study was to compare the contributions of different As- and Fe-reducing bacteria to As biotransformation. In this work, three bacteria strains with different functional genes were employed including Pantoea sp. IMH with the arsC gene, Alkaliphilus oremlandii OhILAs possessing the arrA gene, and Shewanella oneidensis MR-1, an iron reducer. The incubation results showed that Pantoea sp. IMH aerobically reduced 100% of As(V) released from waste residues, though total As release was not enhanced. Similarly, strain OhILAs anaerobically reduced dissolved As(V) but could not enhance As release. In contrast, strain MR-1 substantially enhanced As mobilization because of iron reduction, but without changing the As speciation. The formation of the secondary iron mineral pyrite in the MR-1 incubation experiments, as evidenced by the X-ray absorption near-edge spectroscopy (XANES) analysis, contributed little to the uptake of the freed As. Our results suggest that the arsC gene carriers mainly control the As speciation in the aqueous phase in aerobic environments, whereas in anaerobic conditions, the As speciation should be regulated by arrA gene carriers, and As mobility is greatly enhanced by iron reduction.

  6. Polyacrylamide application versus forest residue mulching for reducing post-fire runoff and soil erosion.

    PubMed

    Prats, Sergio Alegre; Martins, Martinho António Dos Santos; Malvar, Maruxa Cortizo; Ben-Hur, Meni; Keizer, Jan Jacob

    2014-01-15

    For several years now, forest fires have been known to increase overland flow and soil erosion. However, mitigation of these effects has been little studied, especially outside the USA. This study aimed to quantify the effectiveness of two so-called emergency treatments to reduce post-fire runoff and soil losses at the microplot scale in a eucalyptus plantation in north-central Portugal. The treatments involved the application of chopped eucalyptus bark mulch at a rate of 10-12 Mg ha(-1), and surface application of a dry, granular, anionic polyacrylamide (PAM) at a rate of 50 kg ha(-1). During the first year after a wildfire in 2010, 1419 mm of rainfall produced, on average, 785 mm of overland flow in the untreated plots and 8.4 Mg ha(-1) of soil losses. Mulching reduced these two figures significantly, by an average 52 and 93%, respectively. In contrast, the PAM-treated plots did not differ from the control plots, despite slightly lower runoff but higher soil erosion figures. When compared to the control plots, mean key factors for runoff and soil erosion were different in the case of the mulched but not the PAM plots. Notably, the plots on the lower half of the slope registered bigger runoff and erosion figures than those on the upper half of the slope. This could be explained by differences in fire intensity and, ultimately, in pre-fire standing biomass.

  7. Photocaged Arabinose: A Novel Optogenetic Switch for Rapid and Gradual Control of Microbial Gene Expression.

    PubMed

    Binder, Dennis; Bier, Claus; Grünberger, Alexander; Drobietz, Dagmar; Hage-Hülsmann, Jennifer; Wandrey, Georg; Büchs, Jochen; Kohlheyer, Dietrich; Loeschcke, Anita; Wiechert, Wolfgang; Jaeger, Karl-Erich; Pietruszka, Jörg; Drepper, Thomas

    2016-02-15

    Controlling cellular functions by light allows simple triggering of biological processes in a non-invasive fashion with high spatiotemporal resolution. In this context, light-regulated gene expression has enormous potential for achieving optogenetic control over almost any cellular process. Here, we report on two novel one-step cleavable photocaged arabinose compounds, which were applied as light-sensitive inducers of transcription in bacteria. Exposure of caged arabinose to UV-A light resulted in rapid activation of protein production, as demonstrated for GFP and the complete violacein biosynthetic pathway. Moreover, single-cell analysis revealed that intrinsic heterogeneity of arabinose-mediated induction of gene expression was overcome when using photocaged arabinose. We have thus established a novel phototrigger for synthetic bio(techno)logy applications that enables precise and homogeneous control of bacterial target gene expression.

  8. Aerobic production of succinate from arabinose by metabolically engineered Corynebacterium glutamicum.

    PubMed

    Chen, Tao; Zhu, Nianqing; Xia, Huihua

    2014-01-01

    Arabinose is considered as an ideal feedstock for the microbial production of value-added chemicals due to its abundance in hemicellulosic wastes. In this study, the araBAD operon from Escherichia coli was introduced into succinate-producing Corynebacterium glutamicum, which enabled aerobic production of succinate using arabinose as sole carbon source. The engineered strain ZX1 (pXaraBAD, pEacsAgltA) produced 74.4 mM succinate with a yield of 0.58 mol (mol arabinose)(-1), which represented 69.9% of the theoretically maximal yield. Moreover, this strain produced 110.2 mM succinate using combined substrates of glucose and arabinose. To date, this is the highest succinate production under aerobic conditions in minimal medium.

  9. Improvement of L-arabinose fermentation by modifying the metabolic pathway and transport in Saccharomyces cerevisiae.

    PubMed

    Wang, Chengqiang; Shen, Yu; Zhang, Yanyan; Suo, Fan; Hou, Jin; Bao, Xiaoming

    2013-01-01

    The L-arabinose utilization pathway was established in Saccharomyces cerevisiae, by expressing the codon-optimized araA, araB, and araD genes of Lactobacillus plantarum. After overexpressing the TAL1, TKL1, RPE1, RKI1, and GAL2 genes and adaptive evolution, the L-arabinose utilization of the recombinant strain became efficient. The resulting strain displayed a maximum specific growth rate of 0.075 h(-1), a maximum specific L-arabinose consumption rate of 0.61 g h(-1) g(-1) dry cell weight, and a promising ethanol yield of 0.43 g g(-1) from L-arabinose fermentation.

  10. L-arabinose/D-galactose 1-dehydrogenase of Rhizobium leguminosarum bv. trifolii characterised and applied for bioconversion of L-arabinose to L-arabonate with Saccharomyces cerevisiae.

    PubMed

    Aro-Kärkkäinen, Niina; Toivari, Mervi; Maaheimo, Hannu; Ylilauri, Mikko; Pentikäinen, Olli T; Andberg, Martina; Oja, Merja; Penttilä, Merja; Wiebe, Marilyn G; Ruohonen, Laura; Koivula, Anu

    2014-12-01

    Four potential dehydrogenases identified through literature and bioinformatic searches were tested for L-arabonate production from L-arabinose in the yeast Saccharomyces cerevisiae. The most efficient enzyme, annotated as a D-galactose 1-dehydrogenase from the pea root nodule bacterium Rhizobium leguminosarum bv. trifolii, was purified from S. cerevisiae as a homodimeric protein and characterised. We named the enzyme as a L-arabinose/D-galactose 1-dehydrogenase (EC 1.1.1.-), Rl AraDH. It belongs to the Gfo/Idh/MocA protein family, prefers NADP(+) but uses also NAD(+) as a cofactor, and showed highest catalytic efficiency (k cat/K m) towards L-arabinose, D-galactose and D-fucose. Based on nuclear magnetic resonance (NMR) and modelling studies, the enzyme prefers the α-pyranose form of L-arabinose, and the stable oxidation product detected is L-arabino-1,4-lactone which can, however, open slowly at neutral pH to a linear L-arabonate form. The pH optimum for the enzyme was pH 9, but use of a yeast-in-vivo-like buffer at pH 6.8 indicated that good catalytic efficiency could still be expected in vivo. Expression of the Rl AraDH dehydrogenase in S. cerevisiae, together with the galactose permease Gal2 for L-arabinose uptake, resulted in production of 18 g of L-arabonate per litre, at a rate of 248 mg of L-arabonate per litre per hour, with 86 % of the provided L-arabinose converted to L-arabonate. Expression of a lactonase-encoding gene from Caulobacter crescentus was not necessary for L-arabonate production in yeast.

  11. Probing key DNA contacts in AraR-mediated transcriptional repression of the Bacillus subtilis arabinose regulon.

    PubMed

    Franco, Irina Saraiva; Mota, Luís Jaime; Soares, Cláudio Manuel; de Sá-Nogueira, Isabel

    2007-01-01

    In the absence of arabinose, the AraR transcription factor represses the expression of genes involved in the utilization of arabinose, xylose and galactose in Bacillus subtilis. AraR exhibits a chimeric organization: the N-terminal DNA-binding region belongs to the GntR family and the C-terminal effector-binding domain is homologous to the GalR/LacI family. Here, the AraR-DNA-binding interactions were characterized in vivo and in vitro. The effect of residue substitutions in the AraR N-terminal domain and of base-pair exchanges into an AraR-DNA-binding operator site were examined by assaying for AraR-mediated regulatory activity in vivo and DNA-binding activity in vitro. The results showed that residues K4, R45 and Q61, located in or near the winged-helix DNA-binding motif, were the most critical amino acids required for AraR function. In addition, the analysis of the various mutations in an AraR palindromic operator sequence indicated that bases G9, A11 and T16 are crucial for AraR binding. Moreover, an AraR mutant M34T was isolated that partially suppressed the effect of mutations in the regulatory cis-elements. Together, these findings extend the knowledge on the nature of AraR nucleoprotein complexes and provide insight into the mechanism that underlies the mode of action of AraR and its orthologues.

  12. Air-drying beds reduce the quantities of antibiotic resistance genes and class 1 integrons in residual municipal wastewater solids.

    PubMed

    Burch, Tucker R; Sadowsky, Michael J; LaPara, Timothy M

    2013-09-03

    This study investigated whether air-drying beds reduce antibiotic resistance gene (ARG) concentrations in residual municipal wastewater solids. Three laboratory-scale drying beds were operated for a period of nearly 100 days. Real-time PCR was used to quantify 16S rRNA genes, 16S rRNA genes specific to fecal bacteria (AllBac) and human fecal bacteria (HF183), the integrase gene of class 1 integrons (intI1), and five ARGs representing a cross-section of antibiotic classes and resistance mechanisms (erm(B), sul1, tet(A), tet(W), and tet(X)). Air-drying beds were capable of reducing all gene target concentrations by 1 to 5 orders of magnitude, and the nature of this reduction was consistent with both a net decrease in the number of bacterial cells and a lack of selection within the microbial community. Half-lives varied between 1.5 d (HF183) and 5.4 d (tet(X)) during the first 20 d of treatment. After the first 20 d of treatment, however, half-lives varied between 8.6 d (tet(X)) and 19.3 d (AllBac), and 16S rRNA gene, intI1, and sul1 concentrations did not change (P > 0.05). These results demonstrate that air-drying beds can reduce ARG and intI1 concentrations in residual municipal wastewater solids within timeframes typical of operating practices.

  13. Reducing the impurity incorporation from residual gas by ion bombardment during high vacuum magnetron sputtering

    SciTech Connect

    Rosen, Johanna; Widenkvist, Erika; Larsson, Karin; Kreissig, Ulrich; Mraz, Stanislav; Martinez, Carlos; Music, Denis; Schneider, J. M.

    2006-05-08

    The influence of ion energy on the hydrogen incorporation has been investigated for alumina thin films, deposited by reactive magnetron sputtering in an Ar/O{sub 2}/H{sub 2}O environment. Ar{sup +} with an average kinetic energy of {approx}5 eV was determined to be the dominating species in the plasma. The films were analyzed with x-ray diffraction, x-ray photoelectron spectroscopy, and elastic recoil detection analysis, demonstrating evidence for amorphous films with stoichiometric O/Al ratio. As the substrate bias potential was increased from -15 V (floating potential) to -100 V, the hydrogen content decreased by {approx}70%, from 9.1 to 2.8 at. %. Based on ab initio calculations, these results may be understood by thermodynamic principles, where a supply of energy enables surface diffusion, H{sub 2} formation, and desorption [Rosen et al., J. Phys.: Condens. Matter 17, L137 (2005)]. These findings are of importance for the understanding of the correlation between ion energy and film composition and also show a pathway to reduce impurity incorporation during film growth in a high vacuum ambient.

  14. Arabinose-induction of lac-derived promoter systems for penicillin acylase production in Escherichia coli.

    PubMed

    Narayanan, Niju; Hsieh, Ming-Yi; Xu, Yali; Chou, C Perry

    2006-01-01

    Arabinose was shown to serve as an effective inducer for induction of the lac-derived promoters in Escherichia coli using penicillin acylase (PAC) as a model protein. Upon the induction with a conventional inducer, isopropyl-beta-d-thiogalactopyranoside (IPTG), for pac overexpression, which is regulated by the trc or (DE3)/T7 promoter, the production of PAC was limited by the accumulation of PAC precursors (proPAC) as inclusion bodies. Negative cellular responses, such as growth inhibition and cell lysis, were frequently observed, resulting in a low pac expression level and poor culture performance. Interestingly, these technical hurdles can be overcome simply through the use of arabinose as an inducer. The results indicate that arabinose not only induced the lac-derived promoter systems (i.e., trc and (DE3)/T7) for pac (or LL pac) overexpression but also facilitated the posttranslational processing of proPAC for maturation. However, the arabinose-inducibility appears to be host-dependent and becomes less observable in the strains with a mutation in the ara operon. The arabinose-inducibility was also investigated in the expression system with the coexistence of the trc promoter system regulating pac expression and another arabinose-inducible promoter system of araB regulating degP coexpression.

  15. In vivo induction kinetics of the arabinose promoters in Escherichia coli.

    PubMed

    Johnson, C M; Schleif, R F

    1995-06-01

    In Escherichia coli, the AraC protein represses transcription from its own promoter, PC, and when associated with arabinose, activates transcription from three other promoters, PBAD, PE, and PFGH. Expression from all four of these promoters is also regulated by cyclic AMP-catabolite activator protein; however, the arrangement of the protein binding sites is not identical for each promoter. We are interested in determining how the AraC protein is able to activate PBAD, PE, and PFGH despite their differences. We have characterized the induction response of the wild-type arabinose operons from their native chromosomal locations by primer extension analysis. In this analysis, mRNA from the four arabinose operons plus an internal standard could all be assayed in the RNA obtained from a single sample of cells. We found that each of the operons shows a rapid, within 15 to 30 s, response to arabinose. We also found that the expression of araFGH is more sensitive to catabolite repression but not to arabinose concentration than are araE and araBAD. Finally, we have determined the relative levels of inducibility in wild-type cells of araBAD, araFGH, and araE to be 6.5, 5, and 1, respectively. These results provide a basis for subsequent studies to determine the mechanism(s) by which AraC protein activates transcription from the different arabinose promoters.

  16. Timing and dynamics of single cell gene expression in the arabinose utilization system.

    PubMed

    Megerle, Judith A; Fritz, Georg; Gerland, Ulrich; Jung, Kirsten; Rädler, Joachim O

    2008-08-01

    The arabinose utilization system of Escherichia coli displays a stochastic all-or-nothing response at intermediate levels of arabinose, where the population divides into a fraction catabolizing the sugar at a high rate (on-state) and a fraction not utilizing arabinose (off-state). Here we study this decision process in individual cells, focusing on the dynamics of the transition from the off- to the on-state. Using quantitative time-lapse microscopy, we determine the time delay between inducer addition and fluorescence onset of a GFP reporter. Through independent characterization of the GFP maturation process, we can separate the lag time caused by the reporter from the intrinsic activation time of the arabinose system. The resulting distribution of intrinsic time delays scales inversely with the external arabinose concentration, and is compatible with a simple stochastic model for arabinose uptake. Our findings support the idea that the heterogeneous timing of gene induction is causally related to a broad distribution of uptake proteins at the time of sugar addition.

  17. Timing and Dynamics of Single Cell Gene Expression in the Arabinose Utilization System

    NASA Astrophysics Data System (ADS)

    Megerle, J.; Fritz, G.; Gerland, U.; Jung, K.; Radler, J.

    2008-08-01

    The arabinose utilization system of E. coli displays a stochastic "all or nothing" response at intermediate levels of arabinose, where the population divides into a fraction catabolizing the sugar at a high rate (ON state) and a fraction not utilizing arabinose (OFF state). Here we study this decision process in individual cells, focusing on the dynamics of the transition from the OFF to the ON state. Using quantitative time-lapse microscopy, we determine the time delay between inducer addition and fluorescence onset of a GFP reporter. Through independent characterization of the GFP maturation process, we can separate the lag time caused by the reporter from the intrinsic activation time of the arabinose system. The resulting distribution of intrinsic time delays scales inversely with the external arabinose concentration, and is compatible with a simple stochastic model for arabinose uptake. Our findings support the idea that the heterogeneous timing of gene induction is causally related to a broad distribution of uptake proteins at the time of sugar addition.

  18. Bioprospecting and evolving alternative xylose and arabinose pathway enzymes for use in Saccharomyces cerevisiae.

    PubMed

    Lee, Sun-Mi; Jellison, Taylor; Alper, Hal S

    2016-03-01

    Bioprospecting is an effective way to find novel enzymes from strains with desirable phenotypes. Such bioprospecting has enabled organisms such as Saccharomyces cerevisiae to utilize nonnative pentose sugars. Yet, the efficiency of this pentose catabolism (especially for the case of arabinose) remains suboptimal. Thus, further pathway optimization or identification of novel, optimal pathways is needed. Previously, we identified a novel set of xylan catabolic pathway enzymes from a superior pentose-utilizing strain of Ustilago bevomyces. These enzymes were used to successfully engineer a xylan-utilizing S. cerevisiae through a blended approach of bioprospecting and evolutionary engineering. Here, we expanded this approach to xylose and arabinose catabolic pathway engineering and demonstrated that bioprospected xylose and arabinose catabolic pathways from U. bevomyces offer alternative choices for enabling efficient pentose catabolism in S. cerevisiae. By introducing a novel set of xylose catabolic genes from U. bevomyces, growth rates were improved up to 85 % over a set of traditional Scheffersomyces stipitis pathway genes. In addition, we suggested an alternative arabinose catabolic pathway which, after directed evolution and pathway engineering, enabled S. cerevisiae to grow on arabinose as a sole carbon source in minimal medium with growth rates upwards of 0.05 h(-1). This pathway represents the most efficient growth of yeast on pure arabinose minimal medium. These pathways provide great starting points for further strain development and demonstrate the utility of bioprospecting from U. bevomyces.

  19. Long Term Sugarcane Crop Residue Retention Offers Limited Potential to Reduce Nitrogen Fertilizer Rates in Australian Wet Tropical Environments

    PubMed Central

    Meier, Elizabeth A.; Thorburn, Peter J.

    2016-01-01

    The warming of world climate systems is driving interest in the mitigation of greenhouse gas (GHG) emissions. In the agricultural sector, practices that mitigate GHG emissions include those that (1) reduce emissions [e.g., those that reduce nitrous oxide (N2O) emissions by avoiding excess nitrogen (N) fertilizer application], and (2) increase soil organic carbon (SOC) stocks (e.g., by retaining instead of burning crop residues). Sugarcane is a globally important crop that can have substantial inputs of N fertilizer and which produces large amounts of crop residues (‘trash’). Management of N fertilizer and trash affects soil carbon and nitrogen cycling, and hence GHG emissions. Trash has historically been burned at harvest, but increasingly is being retained on the soil surface as a ‘trash blanket’ in many countries. The potential for trash retention to alter N fertilizer requirements and sequester SOC was investigated in this study. The APSIM model was calibrated with data from field and laboratory studies of trash decomposition in the wet tropics of northern Australia. APSIM was then validated against four independent data sets, before simulating location × soil × fertilizer × trash management scenarios. Soil carbon increased in trash blanketed soils relative to SOC in soils with burnt trash. However, further increases in SOC for the study region may be limited because the SOC in trash blanketed soils could be approaching equilibrium; future GHG mitigation efforts in this region should therefore focus on N fertilizer management. Simulated N fertilizer rates were able to be reduced from conventional rates regardless of trash management, because of low yield potential in the wet tropics. For crops subjected to continuous trash blanketing, there was substantial immobilization of N in decomposing trash so conventional N fertilizer rates were required for up to 24 years after trash blanketing commenced. After this period, there was potential to reduce N

  20. D-arabinose metabolism in Escherichia coli B: induction and cotransductional mapping of the L-fucose-D-arabinose pathway enzymes.

    PubMed

    Elsinghorst, E A; Mortlock, R P

    1988-12-01

    D-Arabinose is degraded by Escherichia coli B via some of the L-fucose pathway enzymes and a D-ribulokinase which is distinct from the L-fuculokinase of the L-fucose pathway. We found that L-fucose and D-arabinose acted as the apparent inducers of the enzymes needed for their degradation. These enzymes, including D-ribulokinase, appeared to be coordinately regulated, and mutants which constitutively synthesized the L-fucose enzymes also constitutively synthesized D-ribulokinase. In contrast to D-arabinose-positive mutants of E. coli K-12, in which L-fuculose-1-phosphate and D-ribulose-1-phosphate act as inducers of the L-fucose pathway, we found that these intermediates did not act as inducers in E. coli B. To further characterize the E. coli B system, some of the L-fucose-D-arabinose genes were mapped by using bacteriophage P1 transduction. A transposon Tn10 insertion near the E. coli B L-fucose regulon was used in two- and three-factor reciprocal crosses. The gene encoding D-ribulokinase, designated darK, was found to map within the L-fucose regulon, and the partial gene order was found to be Tn10-fucA-darK-fucI-fucK-thyA.

  1. High-level hemicellulosic arabinose predominately affects lignocellulose crystallinity for genetically enhancing both plant lodging resistance and biomass enzymatic digestibility in rice mutants.

    PubMed

    Li, Fengcheng; Zhang, Mingliang; Guo, Kai; Hu, Zhen; Zhang, Ran; Feng, Yongqing; Yi, Xiaoyan; Zou, Weihua; Wang, Lingqiang; Wu, Changyin; Tian, Jinshan; Lu, Tiegang; Xie, Guosheng; Peng, Liangcai

    2015-05-01

    Rice is a major food crop with enormous biomass residue for biofuels. As plant cell wall recalcitrance basically decides a costly biomass process, genetic modification of plant cell walls has been regarded as a promising solution. However, due to structural complexity and functional diversity of plant cell walls, it becomes essential to identify the key factors of cell wall modifications that could not much alter plant growth, but cause an enhancement in biomass enzymatic digestibility. To address this issue, we performed systems biology analyses of a total of 36 distinct cell wall mutants of rice. As a result, cellulose crystallinity (CrI) was examined to be the key factor that negatively determines either the biomass enzymatic saccharification upon various chemical pretreatments or the plant lodging resistance, an integrated agronomic trait in plant growth and grain production. Notably, hemicellulosic arabinose (Ara) was detected to be the major factor that negatively affects cellulose CrI probably through its interlinking with β-1,4-glucans. In addition, lignin and G monomer also exhibited the positive impact on biomass digestion and lodging resistance. Further characterization of two elite mutants, Osfc17 and Osfc30, showing normal plant growth and high biomass enzymatic digestion in situ and in vitro, revealed the multiple GH9B candidate genes for reducing cellulose CrI and XAT genes for increasing hemicellulosic Ara level. Hence, the results have suggested the potential cell wall modifications for enhancing both biomass enzymatic digestibility and plant lodging resistance by synchronically overexpressing GH9B and XAT genes in rice.

  2. Use of drinking water treatment residuals as a potential best management practice to reduce phosphorus risk index scores.

    PubMed

    Dayton, E A; Basta, N T

    2005-01-01

    The P risk index system has been developed to identify agricultural fields vulnerable to P loss as a step toward protecting surface water. Because of their high Langmuir phosphorus adsorption maxima (P(max)), use of drinking water treatment residuals (WTRs) should be considered as a best management practice (BMP) to lower P risk index scores. This work discusses three WTR application methods that can be used to reduce P risk scores: (i) enhanced buffer strip, (ii) incorporation into a high soil test phosphorus (STP) soil, and (iii) co-blending with manure or biosolids. The relationship between WTR P(max) and reduction in P extractability and runoff P was investigated. In a simulated rainfall experiment, using a buffer strip enhanced with 20 Mg WTR ha(-1), runoff P was reduced by from 66.8 to 86.2% and reductions were related to the WTR P(max). When 25 g kg(-1) WTR was incorporated into a high STP soil of 315 mg kg(-1) determined using Mehlich-3 extraction, 0.01 M calcium chloride-extractable phosphorus (CaCl(2)-P) reductions ranged from 60.9 to 96.0% and were strongly (P < 0.01) related to WTR P(max). At a 100 g kg(-1) WTR addition, Mehlich 3-extractable P reductions ranged from 41.1 to 86.7% and were strongly (P < 0.01) related to WTR P(max). Co-blending WTR at 250 g kg(-1) to manure or biosolids reduced CaCl(2)-P by >75%. The WTR P(max) normalized across WTR application rates (P(max) x WTR application) was significantly related to reductions in CaCl(2)-P or STP. Using WTR as a P risk index modifying factor will promote effective use of WTR as a BMP to reduce P loss from agricultural land.

  3. Molecular cloning of the Escherichia coli B L-fucose-D-arabinose gene cluster.

    PubMed Central

    Elsinghorst, E A; Mortlock, R P

    1994-01-01

    To metabolize the uncommon pentose D-arabinose, enteric bacteria often recruit the enzymes of the L-fucose pathway by a regulatory mutation. However, Escherichia coli B can grow on D-arabinose without the requirement of a mutation, using some of the L-fucose enzymes and a D-ribulokinase that is distinct from the L-fuculokinase of the L-fucose pathway. To study this naturally occurring D-arabinose pathway, we cloned and partially characterized the E. coli B L-fucose-D-arabinose gene cluster and compared it with the L-fucose gene cluster of E. coli K-12. The order of the fucA, -P, -I, and -K genes was the same in the two E. coli strains. However, the E. coli B gene cluster contained a 5.2-kb segment located between the fucA and fucP genes that was not present in E. coli K-12. This segment carried the darK gene, which encodes the D-ribulokinase needed for growth on D-arabinose by E. coli B. The darK gene was not homologous with any of the L-fucose genes or with chromosomal DNA from other D-arabinose-utilizing bacteria. D-Ribulokinase and L-fuculokinase were purified to apparent homogeneity and partially characterized. The molecular weights, substrate specificities, and kinetic parameters of these two enzymes were very dissimilar, which together with DNA hybridization analysis, suggested that these enzymes are not related. D-Arabinose metabolism by E. coli B appears to be the result of acquisitive evolution, but the source of the darK gene has not been determined. Images PMID:7961494

  4. [Application of liquid chromatography in substitution of the radioimmunoassay technique in order to reduce residues generated in health services in research laboratory].

    PubMed

    Ribeiro Neto, Luciane M; Sugawara, Eduardo K; Verreschi, Ieda T N

    2008-10-01

    Designing a Health Care Service Waste Management Plan, according to the RDC 306 rules, is a responsibility of all those who produce such waste. Since radioimmunoassay (RIA) is one of the most employed techniques, we studied the impact of replacing this technique by liquid chromatography (HPLC) with regard to the reduction of the radioactive residues routinely produced by the Unifesp steroid laboratory. The residues produced by the determination of serum cortisol and 17 alpha-hydroxyprogesterone were classified, and those belonging to groups B and C were evaluated. We observed that, when RIA is used, chemical residues (group B) and radioactive waste (group C) are produced, whereas HPLC generates only chemical residues. Adequation of these techniques showed to be advantageous, by significantly reducing the time of analysis and mainly by eliminating and/or reducing the generation of radioactive waste, encouraging its application to other methodologies, as well as its adoption by other research units.

  5. Enhanced activity and stability of L-arabinose isomerase by immobilization on aminopropyl glass.

    PubMed

    Zhang, Ye-Wang; Jeya, Marimuthu; Lee, Jung-Kul

    2011-03-01

    Immobilization of Bacillus licheniformis L: -arabinose isomerase (BLAI) on aminopropyl glass modified with glutaraldehyde (4 mg protein g support⁻¹) was found to enhance the enzyme activity. The immobilization yield of BLAI was proportional to the quantity of amino groups on the surface of support. Reducing particle size increased the adsorption capacity (q(m)) and affinity (k(a)). The pH and temperature for immobilization were optimized to be pH 7.1 and 33 °C using response surface methodology (RSM). The immobilized enzyme was characterized and compared to the free enzyme. There is no change in optimal pH and temperature before and after immobilization. However, the immobilized BLAI enzyme achieved 145% of the activity of the free enzyme. Correspondingly, the catalytic efficiency (k(cat)/K(m)) was improved 1.47-fold after immobilization compared to the free enzyme. The thermal stability was improved 138-fold (t₁/₂) increased from 2 to 275 h) at 50 °C following immobilization.

  6. Functional identification of MSMEG_6402 protein from Mycobacterium smegmatis in decaprenylphosphoryl-D-arabinose biosynthesis.

    PubMed

    Jiang, Tao; Cai, Lina; Zhao, Xiaojiao; He, Lianqi; Ma, Yufang; Zang, Shizhu; Zhang, Cuili; Li, Xinli; Xin, Yi

    2014-11-01

    The arabinogalactan (AG) of the mycobacterial cell wall consists of an arabinan region, a galactan region and a disaccharide linker. Decaprenylphosphoryl-D-arabinose (DPA) is the donor for arabinofuran residues, which are formed from phosphoribose diphosphate (PRPP) and decaprenyl phosphate (DP). DP is sequentially catalyzed by a three-step process that involves a transferase, a phosphatase and an epimerase. Rv3807c is a putative phospholipid phosphatase that might generate the intermediate product of decaprenyl-phosphoryl-ribose (DPR) in DPA biosynthesis. Mycobacterium smegmatis MSMEG_6402 is a homolog gene of Mycobacterium tuberculosis Rv3807c and was substituted for the functional identification of Rv3807c. Previously, we generated a conditional MSMEG_6402 gene knockout strain (M. sm-ΔM_6402) that exhibited significantly affected cell wall structure. To understand the function of MSMEG_6402 in DPA biosynthesis, this gene was amplified and expressed, and the resulting protein was identified and purified using a His-tagged approach. A MSMEG_6402 enzymatic reaction system with PRPP and DP as substrates was utilized, and the reaction products were separated using thin layer chromatography (TLC). The results revealed a specific lipid-linked sugar band that appeared in the reaction with the addition of MSMEG_6402. Furthermore, ESI-MS detection was utilized in this study, and the results revealed that the enzymatic reaction products involving MSMEG_6402 included DPPR and a sodium ion adduct of DPR. Additionally, the phosphatase activity of MSMEG_6402 was also determined through phosphate group detection using the colorimetric method. Based on our results together with the results of previous studies, including the functional identification and bioinformatics analysis of M. tuberculosis Rv3807c, we propose that MSMEG_6402, as a phosphatase, has an intimate relationship with DPA biosynthesis.

  7. Production of Acetoin through Simultaneous Utilization of Glucose, Xylose, and Arabinose by Engineered Bacillus subtilis.

    PubMed

    Zhang, Bo; Li, Xin-Li; Fu, Jing; Li, Ning; Wang, Zhiwen; Tang, Ya-Jie; Chen, Tao

    2016-01-01

    Glucose, xylose and arabinose are the three most abundant monosaccharide found in lignocellulosic biomass. Effectively and simultaneously utilization of these sugars by microorganisms for production of the biofuels and bio-chemicals is essential toward directly fermentation of the lignocellulosic biomass. In our previous study, the recombinant Bacillus subtilis 168ARSRCPΔacoAΔbdhA strain was already shown to efficiently utilize xylose for production of acetoin, with a yield of 0.36 g/g xylose. In the current study, the Bacillus subtilis168ARSRCPΔacoAΔbdhA strain was further engineered to produce acetoin from a glucose, xylose, and arabinose mixtures. To accomplish this, the endogenous xylose transport protein AraE, the exogenous xylose isomerase gene xylA and the xylulokinase gene xylB from E. coli were co-overexpressed in the Bacillus subtilis 168ARSRCPΔacoAΔbdhA strain, which enabled the resulting strain, denoted ZB02, to simultaneously utilize glucose and xylose. Unexpectedly, the ZB02 strain could simultaneously utilize glucose and arabinose also. Further results indicated that the transcriptional inhibition of the arabinose transport protein gene araE was the main limiting factor for arabinose utilization in the presence of glucose. Additionally, the arabinose operon in B. subtilis could be activated by the addition of arabinose, even in the presence of glucose. Through fed-batch fermentation, strain ZB02 could simultaneously utilize glucose, xylose, and arabinose, with an average sugar consumption rate of 3.00 g/l/h and an average production of 62.2 g/l acetoin at a rate of 0.864 g/l/h. Finally, the strain produced 11.2 g/l acetoin from lignocellulosic hydrolysate (containing 20.6g/l glucose, 12.1 g/l xylose and 0.45 g/l arabinose) in flask cultivation, with an acetoin yield of 0.34 g/g total sugar. The result demonstrates that this strain has good potential for the utilization of lignocellulosic hydrolysate for production of acetoin.

  8. Production of Acetoin through Simultaneous Utilization of Glucose, Xylose, and Arabinose by Engineered Bacillus subtilis

    PubMed Central

    Fu, Jing; Li, Ning; Wang, Zhiwen; Tang, Ya-jie; Chen, Tao

    2016-01-01

    Glucose, xylose and arabinose are the three most abundant monosaccharide found in lignocellulosic biomass. Effectively and simultaneously utilization of these sugars by microorganisms for production of the biofuels and bio-chemicals is essential toward directly fermentation of the lignocellulosic biomass. In our previous study, the recombinant Bacillus subtilis 168ARSRCPΔacoAΔbdhA strain was already shown to efficiently utilize xylose for production of acetoin, with a yield of 0.36 g/g xylose. In the current study, the Bacillus subtilis168ARSRCPΔacoAΔbdhA strain was further engineered to produce acetoin from a glucose, xylose, and arabinose mixtures. To accomplish this, the endogenous xylose transport protein AraE, the exogenous xylose isomerase gene xylA and the xylulokinase gene xylB from E. coli were co-overexpressed in the Bacillus subtilis 168ARSRCPΔacoAΔbdhA strain, which enabled the resulting strain, denoted ZB02, to simultaneously utilize glucose and xylose. Unexpectedly, the ZB02 strain could simultaneously utilize glucose and arabinose also. Further results indicated that the transcriptional inhibition of the arabinose transport protein gene araE was the main limiting factor for arabinose utilization in the presence of glucose. Additionally, the arabinose operon in B. subtilis could be activated by the addition of arabinose, even in the presence of glucose. Through fed-batch fermentation, strain ZB02 could simultaneously utilize glucose, xylose, and arabinose, with an average sugar consumption rate of 3.00 g/l/h and an average production of 62.2 g/l acetoin at a rate of 0.864 g/l/h. Finally, the strain produced 11.2 g/l acetoin from lignocellulosic hydrolysate (containing 20.6g/l glucose, 12.1 g/l xylose and 0.45 g/l arabinose) in flask cultivation, with an acetoin yield of 0.34 g/g total sugar. The result demonstrates that this strain has good potential for the utilization of lignocellulosic hydrolysate for production of acetoin. PMID:27467131

  9. Is L-arabinose important for the endophytic lifestyle of Pseudomonas spp.?

    PubMed

    Malfanova, Natalia; Kamilova, Faina; Validov, Shamil; Chebotar, Vladimir; Lugtenberg, Ben

    2013-01-01

    Twenty endophytic bacteria were isolated from surface-sterilized stems and roots of cucumber plants. After removal of potential siblings and human pathogens, the remaining seven strains were identified based on their 16S rDNA as Pseudomonas fluorescens (2 strains) and P. putida (5 strains). Three strains, namely P. fluorescens CS1, P. fluorescens CR2 and P. putida CR3, were able to suppress tomato foot and root rot (TFRR). Special attention was paid to the characterization of the BIOLOG carbon oxidation profiles of the isolated pseudomonads in order to identify nutrients which might be important for their endophytic lifestyle. Comparative analysis of the profiles of these seven strains with those of seven rhizospheric Pseudomonas spp. revealed that endophytes were able to oxidize L-arabinose and 2,3-butanediol significantly more often than the rhizospheric group. An independent growth experiment performed in tubes using L-arabinose and 2,3-butanediol as sole carbon sources showed the same results as seen using BIOLOG for L-arabinose, but not for 2,3-butanediol. Since L-arabinose is one of the most abundant sugars in xylem of cucumber plants and was not detected in their rhizosphere, our data suggest that utilization of L-arabinose might be a trait contributing to the endophytic lifestyle of the isolated Pseudomonas endophytes.

  10. Metabolome, transcriptome and metabolic flux analysis of arabinose fermentation by engineered Saccharomyces cerevisiae.

    PubMed

    Wisselink, H Wouter; Cipollina, Chiara; Oud, Bart; Crimi, Barbara; Heijnen, Joseph J; Pronk, Jack T; van Maris, Antonius J A

    2010-11-01

    One of the challenges in strain improvement by evolutionary engineering is to subsequently determine the molecular basis of the improved properties that were enriched from the natural genetic variation during the selective conditions. This study focuses on Saccharomyces cerevisiae IMS0002 which, after metabolic and evolutionary engineering, ferments the pentose sugar arabinose. Glucose- and arabinose-limited anaerobic chemostat cultures of IMS0002 and its non-evolved ancestor were subjected to transcriptome analysis, intracellular metabolite measurements and metabolic flux analysis. Increased expression of the GAL-regulon and deletion of GAL2 in IMS0002 confirmed that the galactose transporter is essential for growth on arabinose. Elevated intracellular concentrations of pentose-phosphate-pathway intermediates and upregulation of TKL2 and YGR043c (encoding transketolase and transaldolase isoenzymes) suggested an involvement of these genes in flux-controlling reactions in arabinose fermentation. Indeed, deletion of these genes in IMS0002 caused a 21% reduction of the maximum specific growth rate on arabinose.

  11. L-Arabinose-sensitive, L-ribulose 5-phosphate 4-epimerase-deficient mutants of Escherichia coli.

    PubMed

    ENGLESBERG, E; ANDERSON, R L; WEINBERG, R; LEE, N; HOFFEE, P; HUTTENHAUER, G; BOYER, H

    1962-07-01

    Englesberg, E. (University of Pittsburgh, Pittsburgh, Pa.), R L. Anderson, R. Weinberg, N. Lee, P. Hoffee, G. Huttenhauer, and H. Boyer. l-Arabinose-sensitive, l-ribulose 5-phosphate 4-epimerase-deficient mutants of Escherichia coli. J. Bacteriol. 84:137-146. 1962-l-Arabinose-negative mutants of Escherichia coli B/r, ara-53 and ara-139, are deficient in the enzyme l-ribulose 5-phosphate 4-epimerase; ara-53, further analyzed, accumulates large quantities of l-ribulose 5-phosphate when incubated with l-arabinose. The mutant sites are closely linked to the left of the previously ordered l-arabinose mutant sites, and probably represent the structural gene for l-ribulose 5-phosphate 4-epimerase (gene D) in the l-arabinose operon. The inducible levels of l-arabinose isomerase and l-ribulose 5-phosphate 4-epimerase vary correspondingly as a result of mutation in the structural gene for l-ribulokinase (gene B), further substantiating the dual structural and regulatory function of this gene locus. Ara-53 and ara-139 are strongly inhibited by l-arabinose and give rise to l-arabinose-resistant mutants. The one resistant mutant analyzed still lacks the 4-epimerase but is deficient in l-ribulokinase and has increased l-arabinose isomerase activity, a characteristic of a type of mutation in the B gene. It is proposed that accumulation of l-ribulose 5-phosphate is responsible for the inhibition, and that mutation to resistance will involve mutation in the A, B, C, permease, or repressor genes, thus providing a direct method for isolating these types of l-arabinose-negative mutants. Glucose prevents and cures the l-arabinose inhibition.

  12. Induction kinetics of the L-arabinose operon of Escherichia coli.

    PubMed

    Schleif, R; Hess, W; Finkelstein, S; Ellis, D

    1973-07-01

    After addition of l-arabinose to growing Escherichia coli, the l-ribulokinase (EC 2.7.1.16) and l-arabinose isomerase (EC 5.3.1.4) first appear at about 0.7 and 1.4 min, respectively. These times are consistent with the distances of the genes from the ribonucleic acid polymerase initiation site in the operon. The kinetics of appearance of these enzymes as well as those of beta-galactosidase (EC 3.2.1.23) in the same strain are consistent with a peptide elongation rate of no less than 14 amino acids per second. A measurement of the average peptide elongation rate made by measuring the kinetics of radioactive amino acid appearance in completed polypeptides yielded a rate of about 12 amino acids per s. Convenient assays of the arabinose isomerase and ribulokinase are also given.

  13. 13C metabolic flux analysis in Clostridium acetobutylicum during growth on L-arabinose

    NASA Astrophysics Data System (ADS)

    Hurley, Margaret; Sund, Christian; Liu, Sanchao; Germane, Katherine; Servinsky, Matthew; Gerlach, Elliot

    2015-03-01

    Clostridium acetobutylicum's metabolic pathways have been studied for decades due to its metabolic diversity and industrial value, yet many details of its metabolism are continuing to emerge. To elucidate the role of xylulose-5-P/fructose-6-P phosphoketolase (XFP), and the recently discovered Pentose Phosphate Pathway (PKP) in C. acetobutylicum, experimental and computational metabolic isotope analysis was performed under growth on glucose, xylose, and arabinose. Results indicate that PKP utilization increased with increasing xylose concentration and this trend was further pronounced during growth on arabinose. This was confirmed by mutation of the gene encoding XFP, which almost completely abolished flux through the PKP during growth on arabinose and resulted in decreased acetate:butyrate ratios. We discuss these experimental and computational results here, and the implications for our understanding of sugar metabolism in C. acetobutylicum.

  14. Directed evolution of AraC for improved compatibility of arabinose- and lactose-inducible promoters.

    PubMed

    Lee, Sung Kuk; Chou, Howard H; Pfleger, Brian F; Newman, Jack D; Yoshikuni, Yasuo; Keasling, Jay D

    2007-09-01

    Synthetic biological systems often require multiple, independently inducible promoters in order to control the expression levels of several genes; however, cross talk between the promoters limits this ability. Here, we demonstrate the directed evolution of AraC to construct an arabinose-inducible (P(BAD)) system that is more compatible with IPTG (isopropyl-beta-D-1-thiogalactopyranoside) induction of a lactose-inducible (P(lac)) system. The constructed system is 10 times more sensitive to arabinose and tolerates IPTG significantly better than the wild type. Detailed studies indicate that the AraC dimerization domain and C terminus are important for the increased sensitivity of AraC to arabinose.

  15. Study of the surface-enhanced Raman spectroscopy of residual impurities in hydroxylamine-reduced silver colloid and the effects of anions on the colloid activity.

    PubMed

    Dong, Xiao; Gu, Huaimin; Liu, Fangfang

    2012-03-01

    The paper investigated the residual ions in hydroxylamine-reduced silver colloid (HRSC) and the relationship between the condition of HRSC and the enhanced mechanisms of this colloid. We also detected the SERS of MB and studied the effects of anions on the Raman signal. In the case of HRSC, the bands of residual ions diminish while the bands of Ag-anions increase gradually with increasing the concentrations of Cl(-) and NO(3)(-). It means the affinity of residual ions on the silver surface is weaker than that of Cl(-) and NO(3)(-) and the residual ions are replaced gradually by the added Cl(-) or NO(3)(-). The Raman signal of residual ions can be detected by treatment with anions that do not bind strongly to the silver surface, such as SO(4)(2-). The most intense band of Ag-anions bonds can be also observed when adding weakly binding anions to the colloid. However, the anions which make up the Ag-anions bonds are residual Cl(-) and the effect of weakly binding anions is only to aggregate the silver particles. Residual Cl(-) can be replaced by I(-) which has the highest affinity. From the detection of methylene blue (MB), the effects of anions on the enhancement of Raman signal are discussed in detail, and these findings could make the conditions suitable for detecting analytes in high efficiency. This study will have a profound implication to SERS users about their interpretation of SERS spectra when obtaining these anomalous bands.

  16. Random-type scanning patterns in laser shock peening without absorbing coating in 2024-T351 Al alloy: A solution to reduce residual stress anisotropy

    NASA Astrophysics Data System (ADS)

    Correa, C.; Peral, D.; Porro, J. A.; Díaz, M.; Ruiz de Lara, L.; García-Beltrán, A.; Ocaña, J. L.

    2015-10-01

    Laser Shock Peening (LSP) is considered as an alternative technology to shot peening (SP) for the induction of compressive residual stresses in metallic alloys in order to improve their fatigue, corrosion and wear resistance. Since laser pulses generated by high-intensity laser systems cover only a small area, laser pulses are generally overlapped and scanned in a zigzag-type pattern to cover completely the surface to be treated. However, zigzag-type scanning patterns induce residual stress anisotropy as collateral effect. The purpose of this paper is to describe and explain, for the first time and with the aid of the numerical model developed by the authors, the influence of the scanning pattern directionality on the residual stress tensor. As an effective solution, the authors propose the application of random-type scanning patterns instead of zigzag-type in order to reduce the mentioned residual stress anisotropy.

  17. An alum-based water treatment residual can reduce extractable phosphorus concentrations in three phosphorus-enriched coastal plain soils.

    PubMed

    Novak, J M; Watts, D W

    2005-01-01

    The accumulation of excess soil phosphorus (P) in watersheds under intensive animal production has been linked to increases in dissolved P concentrations in rivers and streams draining these watersheds. Reductions in water dissolved P concentrations through very strong P sorption reactions may be obtainable after land application of alum-based drinking water treatment residuals (WTRs). Our objectives were to (i) evaluate the ability of an alum-based WTR to reduce Mehlich-3 phosphorus (M3P) and water-soluble phosphorus (WSP) concentrations in three P-enriched Coastal Plain soils, (ii) estimate WTR application rates necessary to lower soil M3P levels to a target 150 mg kg(-1) soil M3P concentration threshold level, and (iii) determine the effects on soil pH and electrical conductivity (EC). Three soils containing elevated M3P (145-371 mg kg(-1)) and WSP (12.3-23.5 mg kg(-1)) concentrations were laboratory incubated with between 0 and 6% WTR (w w(-1)) for 84 d. Incorporation of WTR into the three soils caused a near linear and significant reduction in soil M3P and WSP concentrations. In two soils, 6% WTR application caused a soil M3P concentration decrease to below the soil P threshold level. An additional incubation on the third soil using higher WTR to soil treatments (10-15%) was required to reduce the mean soil M3P concentration to 178 mg kg(-1). After incubation, most treatments had less than a half pH unit decline and a slight increase in soil EC values suggesting a minimal impact on soil quality properties. The results showed that WTR incorporation into soils with high P concentrations caused larger relative reductions in extractable WSP than M3P concentrations. The larger relative reductions in the extractable WSP fraction suggest that WTR can be more effective at reducing potential runoff P losses than usage as an amendment to lower M3P concentrations.

  18. Dielectric properties of two diastereoisomers of the arabinose and their equimolar mixture.

    PubMed

    Kaminski, Kamil; Kaminska, Ewa; Pawlus, Sebastian; Wlodarczyk, Patryk; Paluch, Marian; Ziolo, Jerzy; Kasprzycka, Anna; Szeja, Wiesław; Ngai, K L; Pilch, Jerzy

    2009-12-14

    Dielectric relaxation measurements were performed on two enantiomers, D- and L-arabinose and their equimolar mixture, and compared to dielectric data obtained for D-ribose. D-Arabinose differs from d-ribose by having the opposite configuration at C2. This study reveals that both D- and L- of arabinose exhibit alpha-relaxation peaks with the same shape for the same alpha-relaxation time tau(alpha), and the same steepness index for the T(g)-scale T-dependence of tau(alpha). However, the two isomers have slightly different glass transition temperatures T(g)'s, and their secondary gamma-relaxation times also differ slightly from the previously observed gamma-relaxation in D-ribose at the same temperature. However, when samples of both investigated monosaccharides are annealed at higher temperatures, their glass transition temperatures become nearly identical. This is an effect of the mutarotation process, which leads to the formation of pairs of the enantiomers and accordingly they should have the same physical properties. The width of the alpha-relaxation of D- and L-arabinose is broader than that of D-ribose, as reflected by the smaller stretch exponent in the Kohlrausch-Williams-Watts function used to fit the data of the former (beta(KWW)=0.46+/-0.01) than the latter (beta(KWW)=0.55+/-0.01). The width of the alpha-relaxation of racemic mixture of the D- and L-arabinose is slightly broader than that of the pure isomers. While the dielectric loss data of D-ribose in the glassy state at ambient and elevated pressures show an inflexion indicating the presence of the JG beta-relaxation, the data of D- and L-arabinose show no such feature for identification of the supposedly universal JG beta-relaxation. Nevertheless, on comparing the loss spectra of D-arabinose with that of D-ribose, the presence of the JG beta-relaxation in D-arabinose has been rationalized.

  19. Confirmation and elimination of xylose metabolism bottlenecks in glucose phosphoenolpyruvate-dependent phosphotransferase system-deficient Clostridium acetobutylicum for simultaneous utilization of glucose, xylose, and arabinose.

    PubMed

    Xiao, Han; Gu, Yang; Ning, Yuanyuan; Yang, Yunliu; Mitchell, Wilfrid J; Jiang, Weihong; Yang, Sheng

    2011-11-01

    Efficient cofermentation of D-glucose, D-xylose, and L-arabinose, three major sugars present in lignocellulose, is a fundamental requirement for cost-effective utilization of lignocellulosic biomass. The Gram-positive anaerobic bacterium Clostridium acetobutylicum, known for its excellent capability of producing ABE (acetone, butanol, and ethanol) solvent, is limited in using lignocellulose because of inefficient pentose consumption when fermenting sugar mixtures. To overcome this substrate utilization defect, a predicted glcG gene, encoding enzyme II of the D-glucose phosphoenolpyruvate-dependent phosphotransferase system (PTS), was first disrupted in the ABE-producing model strain Clostridium acetobutylicum ATCC 824, resulting in greatly improved D-xylose and L-arabinose consumption in the presence of D-glucose. Interestingly, despite the loss of GlcG, the resulting mutant strain 824glcG fermented D-glucose as efficiently as did the parent strain. This could be attributed to residual glucose PTS activity, although an increased activity of glucose kinase suggested that non-PTS glucose uptake might also be elevated as a result of glcG disruption. Furthermore, the inherent rate-limiting steps of the D-xylose metabolic pathway were observed prior to the pentose phosphate pathway (PPP) in strain ATCC 824 and then overcome by co-overexpression of the D-xylose proton-symporter (cac1345), D-xylose isomerase (cac2610), and xylulokinase (cac2612). As a result, an engineered strain (824glcG-TBA), obtained by integrating glcG disruption and genetic overexpression of the xylose pathway, was able to efficiently coferment mixtures of D-glucose, D-xylose, and L-arabinose, reaching a 24% higher ABE solvent titer (16.06 g/liter) and a 5% higher yield (0.28 g/g) compared to those of the wild-type strain. This strain will be a promising platform host toward commercial exploitation of lignocellulose to produce solvents and biofuels.

  20. Novel evolutionary engineering approach for accelerated utilization of glucose, xylose, and arabinose mixtures by engineered Saccharomyces cerevisiae strains.

    PubMed

    Wisselink, H Wouter; Toirkens, Maurice J; Wu, Qixiang; Pronk, Jack T; van Maris, Antonius J A

    2009-02-01

    Lignocellulosic feedstocks are thought to have great economic and environmental significance for future biotechnological production processes. For cost-effective and efficient industrial processes, complete and fast conversion of all sugars derived from these feedstocks is required. Hence, simultaneous or fast sequential fermentation of sugars would greatly contribute to the efficiency of production processes. One of the main challenges emerging from the use of lignocellulosics for the production of ethanol by the yeast Saccharomyces cerevisiae is efficient fermentation of D-xylose and L-arabinose, as these sugars cannot be used by natural S. cerevisiae strains. In this study, we describe the first engineered S. cerevisiae strain (strain IMS0003) capable of fermenting mixtures of glucose, xylose, and arabinose with a high ethanol yield (0.43 g g(-1) of total sugar) without formation of the side products xylitol and arabinitol. The kinetics of anaerobic fermentation of glucose-xylose-arabinose mixtures were greatly improved by using a novel evolutionary engineering strategy. This strategy included a regimen consisting of repeated batch cultivation with repeated cycles of consecutive growth in three media with different compositions (glucose, xylose, and arabinose; xylose and arabinose; and only arabinose) and allowed rapid selection of an evolved strain (IMS0010) exhibiting improved specific rates of consumption of xylose and arabinose. This evolution strategy resulted in a 40% reduction in the time required to completely ferment a mixture containing 30 g liter(-1) glucose, 15 g liter(-1) xylose, and 15 g liter(-1) arabinose.

  1. Web-Based Intervention in Mindfulness Meditation for Reducing Residual Depressive Symptoms and Relapse Prophylaxis: A Qualitative Study

    PubMed Central

    2014-01-01

    Background Mindful Mood Balance (MMB) is a Web-based intervention designed to treat residual depressive symptoms and prevent relapse. MMB was designed to deliver the core concepts of mindfulness-based cognitive therapy (MBCT), a group treatment, which, despite its strong evidence base, faces a number of dissemination challenges. Objective The present study is a qualitative investigation of participants’ experiences with MMB. Methods Qualitative content analysis was conducted via 38 exit interviews with MMB participants. Study inclusion required a current PHQ-9 (Patient Health Questionnaire) score ≤12 and lifetime history ≥1 major depressive episode. Feedback was obtained on specific website components, program content, and administration as well as skills learned. Results Codes were assigned to interview responses and organized into four main themes: MBCT Web content, MBCT Web-based group process, home practice, and evidence of concept comprehension. Within these four areas, participants highlighted the advantages and obstacles of translating and delivering MBCT in a Web-based format. Adding increased support was suggested for troubleshooting session content as well as managing time challenges for completing home mindfulness practice. Participants endorsed developing affect regulation skills and identified several advantages to Web-based delivery including flexibility, reduced cost, and time commitment. Conclusions These findings support the viability of providing MBCT online and are consistent with prior qualitative accounts derived from in-person MBCT groups. While there is certainly room for innovation in the domains of program support and engagement, the high levels of participant satisfaction indicated that MMB can significantly increase access to evidence-based psychological treatments for sub-threshold symptoms of unipolar affective disorder. PMID:24662625

  2. Overexpression, purification, crystallization and preliminary X-ray crystal analysis of Bacillus pallidus d-arabinose isomerase

    PubMed Central

    Takeda, Kosei; Yoshida, Hiromi; Takada, Goro; Izumori, Ken; Kamitori, Shigehiro

    2008-01-01

    d-Arabinose isomerase catalyzes the isomerization of d-arabinose to d-ribulose. Bacillus pallidus d-arabinose isomerase has broad substrate specificity and can catalyze the isomerization of d-arabinose, l-fucose, l-xylose, l-galactose and d-­altrose. Recombinant B. pallidus d-arabinose isomerase was overexpressed, purified and crystallized. A crystal of the enzyme was obtained by the sitting-drop method at room temperature and belonged to the orthorhombic space group P21212, with unit-cell parameters a = 144.9, b = 127.9, c = 109.5 Å. Diffraction data were collected to 2.3 Å resolution. PMID:18931442

  3. The mur4 mutant of arabidopsis is partially defective in the de novo synthesis of uridine diphospho L-arabinose

    SciTech Connect

    Burget, E.G.; Reiter, W.D.

    1999-10-01

    To obtain information on the synthesis and function of arabinosylated glycans, the mur4 mutant of arabidopsis was characterized. This mutation leads to a 50% reduction in the monosaccharide L-arabinose in most organs and affects arabinose-containing pectic cell wall polysaccharides and arabinogalactan proteins. Feeding L-arabinose to mur4 plants restores the cell wall composition to wild-type levels, suggesting a partial defect in the de novo synthesis of UDP-L-arabinose, the activated sugar used by arabinosyltransferases. The defect was traced to the conversion of UDP-D-xylose to UDP-L-arabinose in the microsome fraction of leaf material, indicating that mur4 plants are defective in a membrane-bound UDP-D-xylose 4-epimerase.

  4. A novel method to prepare L-Arabinose from xylose mother liquor by yeast-mediated biopurification

    PubMed Central

    2011-01-01

    Background L-arabinose is an important intermediate for anti-virus drug synthesis and has also been used in food additives for diets-controlling in recent years. Commercial production of L-arabinose is a complex progress consisting of acid hydrolysis of gum arabic, followed by multiple procedures of purification, thus making high production cost. Therefore, there is a biotechnological and commercial interest in the development of new cost-effective and high-performance methods for obtaining high purity grade L-arabinose. Results An alternative, economical method for purifying L-arabinose from xylose mother liquor was developed in this study. After screening 306 yeast strains, a strain of Pichia anomala Y161 was selected as it could effectively metabolize other sugars but not L-arabinose. Fermentation in a medium containing xylose mother liquor permitted enrichment of L-arabinose by a significant depletion of other sugars. Biochemical analysis of this yeast strain confirmed that its poor capacity for utilizing L-arabinose was due to low activities of the enzymes required for the metabolism of this sugar. Response surface methodology was employed for optimization the fermentation conditions in shake flask cultures. The optimum conditions were: 75 h fermentation time, at 32.5°C, in a medium containing 21% (v/v) xylose mother liquor. Under these conditions, the highest purity of L-arabinose reached was 86.1% of total sugar, facilitating recovery of white crystalline L-arabinose from the fermentation medium by simple methods. Conclusion Yeast-mediated biopurification provides a dynamic method to prepare high purity of L-arabinose from the feedstock solution xylose mother liqour, with cost-effective and high-performance properties. PMID:21649890

  5. Arabinose-leucine deletion mutants of Escherichia coli B-r.

    PubMed

    Kessler, D P; Englesberg, E

    1969-06-01

    The control of ara gene expression was studied in mutants of Escherichia coli B/r containing deletions which fused the l-arabinose gene complex with the leucine operon (the normal gene order being araDABIOC...leuDCBAO). Complementation experiments with stable merodiploids showed that expression of ara genes cis to araC-leu deletions was controlled by the trans-acting product of the araC gene. Expression of ara genes cis to araB-leu deletions was under leucine control. These studies confirm the existence of a region between genes araC and araB essential for normal activator controlled expression of the ara structural genes. One deletion was characterized as an araO-leu deletion. Its effect on ara gene expression was unique in that ara genes were susceptible to potential regulation by both l-arabinose and leucine. These experiments suggest that two different species of messenger ribonucleic acid (mRNA) may be produced for the ara-leu region as a result of this deletion. One, under l-arabinose-activator control, is initiated in the l-arabinose region; the other, under leucine control, is initiated in the leucine region. The latter indicates that araI can be transcribed. Whether araI is transcribed in the former instance (mRNA made under activator control) remains to be established.

  6. Arabinose is metabolized via a phosphoketolase pathway in Clostridium acetobutylicum ATCC 824.

    PubMed

    Servinsky, M D; Germane, K L; Liu, S; Kiel, J T; Clark, A M; Shankar, J; Sund, C J

    2012-12-01

    In this report, a novel zymogram assay and coupled phosphoketolase assay were employed to demonstrate that Clostridium acetobutylicum gene CAC1343 encodes a bi-functional xylulose-5-P/fructose-6-P phosphoketolase (XFP). The specific activity of purified recombinant XFP was 6.9 U/mg on xylulose-5-P and 21 U/mg on fructose-6-P, while the specific activity of XFP in concentrated C. acetobutylicum whole-cell extract was 0.094 and 0.52 U/mg, respectively. Analysis of crude cell extracts indicated that XFP activity was present in cells grown on arabinose but not glucose and quantitative PCR was used to show that CAC1343 mRNA expression was induced 185-fold during growth on arabinose when compared to growth on glucose. HPLC analysis of metabolites revealed that during growth on xylose and glucose more butyrate than acetate was formed with final acetate:butyrate ratios of 0.72 and 0.83, respectively. Growth on arabinose caused a metabolic shift to more oxidized products with a final acetate:butyrate ratio of 1.95. The shift towards more oxidized products is consistent with the presence of an XFP, suggesting that arabinose is metabolized via a phosphoketolase pathway while xylose is probably metabolized via the pentose phosphate pathway.

  7. In vivo single-molecule kinetics of activation and subsequent activity of the arabinose promoter.

    PubMed

    Mäkelä, Jarno; Kandhavelu, Meenakshisundaram; Oliveira, Samuel M D; Chandraseelan, Jerome G; Lloyd-Price, Jason; Peltonen, Juha; Yli-Harja, Olli; Ribeiro, Andre S

    2013-07-01

    Using a single-RNA detection technique in live Escherichia coli cells, we measure, for each cell, the waiting time for the production of the first RNA under the control of PBAD promoter after induction by arabinose, and subsequent intervals between transcription events. We find that the kinetics of the arabinose intake system affect mean and diversity in RNA numbers, long after induction. We observed the same effect on Plac/ara-1 promoter, which is inducible by arabinose or by IPTG. Importantly, the distribution of waiting times of Plac/ara-1 is indistinguishable from that of PBAD, if and only if induced by arabinose alone. Finally, RNA production under the control of PBAD is found to be a sub-Poissonian process. We conclude that inducer-dependent waiting times affect mean and cell-to-cell diversity in RNA numbers long after induction, suggesting that intake mechanisms have non-negligible effects on the phenotypic diversity of cell populations in natural, fluctuating environments.

  8. Aggregation-based detection of M. smegmatis using D-arabinose-functionalized fluorescent silica nanoparticles.

    PubMed

    Jayawardana, Kalana W; Wijesundera, Samurdhi A; Yan, Mingdi

    2015-11-14

    Fluorescein-doped silica nanoparticles (FSNPs) functionalized with D-arabinose (Ara) showed strong interactions with Mycobacterium smegmatis (M. smegmatis) and caused the bacteria to aggregate. This aggregate formation was used as a means to detect M. smegmatis at the concentration of 10(4) CFU per mL.

  9. Arabinose-Leucine Deletion Mutants of Escherichia coli B/r

    PubMed Central

    Kessler, Donald P.; Englesberg, Ellis

    1969-01-01

    The control of ara gene expression was studied in mutants of Escherichia coli B/r containing deletions which fused the l-arabinose gene complex with the leucine operon (the normal gene order being araDABIOC...leuDCBAO). Complementation experiments with stable merodiploids showed that expression of ara genes cis to araC-leu deletions was controlled by the trans-acting product of the araC gene. Expression of ara genes cis to araB-leu deletions was under leucine control. These studies confirm the existence of a region between genes araC and araB essential for normal activator controlled expression of the ara structural genes. One deletion was characterized as an araO-leu deletion. Its effect on ara gene expression was unique in that ara genes were susceptible to potential regulation by both l-arabinose and leucine. These experiments suggest that two different species of messenger ribonucleic acid (mRNA) may be produced for the ara-leu region as a result of this deletion. One, under l-arabinose-activator control, is initiated in the l-arabinose region; the other, under leucine control, is initiated in the leucine region. The latter indicates that araI can be transcribed. Whether araI is transcribed in the former instance (mRNA made under activator control) remains to be established. PMID:4892369

  10. Arabinose and xylose fermentation by recombinant Saccharomyces cerevisiae expressing a fungal pentose utilization pathway

    PubMed Central

    Bettiga, Maurizio; Bengtsson, Oskar; Hahn-Hägerdal, Bärbel; Gorwa-Grauslund, Marie F

    2009-01-01

    Background Sustainable and economically viable manufacturing of bioethanol from lignocellulose raw material is dependent on the availability of a robust ethanol producing microorganism, able to ferment all sugars present in the feedstock, including the pentose sugars L-arabinose and D-xylose. Saccharomyces cerevisiae is a robust ethanol producer, but needs to be engineered to achieve pentose sugar fermentation. Results A new recombinant S. cerevisiae strain expressing an improved fungal pathway for the utilization of L-arabinose and D-xylose was constructed and characterized. The new strain grew aerobically on L-arabinose and D-xylose as sole carbon sources. The activities of the enzymes constituting the pentose utilization pathway(s) and product formation during anaerobic mixed sugar fermentation were characterized. Conclusion Pentose fermenting recombinant S. cerevisiae strains were obtained by the expression of a pentose utilization pathway of entirely fungal origin. During anaerobic fermentation the strain produced biomass and ethanol. L-arabitol yield was 0.48 g per gram of consumed pentose sugar, which is considerably less than previously reported for D-xylose reductase expressing strains co-fermenting L-arabinose and D-xylose, and the xylitol yield was 0.07 g per gram of consumed pentose sugar. PMID:19630951

  11. Cloning, expression, and transcription analysis of L-arabinose isomerase gene from Mycobacterium smegmatis SMDU.

    PubMed

    Takata, Goro; Poonperm, Wayoon; Rao, Devendar; Souda, Akane; Nishizaki, Tomoe; Morimoto, Kenji; Izumori, Ken

    2007-12-01

    The L-arabinose metabolic gene cluster, araA, araB, araD, araG, araH and araR, encoding L-arabinose isomerase (L-AI) and its accessory proteins was cloned from Mycobacterium smegmatis SMDU and sequenced. The deduced amino acid sequence of araA displayed highest identity with that of Bacillus subtilis (52%). These six genes comprised the L-arabinose operon, and its genetic arrangement was similar to that of B. subtilis. The L-AI gene (araA), encoding a 501 amino acid protein with a calculated molecular mass of 54,888 Da, was expressed in Escherichia coli. The productivity and overall enzymatic properties of the recombinant L-AI were almost same as the authentic L-AI from M. smegmatis. Although the recombinant L-AI showed high substrate specificity, as did L-AI from other organisms, this enzyme catalyzed not only isomerization of L-arabinose-L-ribulose and D-galactose-D-tagatose but also isomerization of L-altrose-L-psicose and L-erythrulose-L-threose. In combination with L-AI from M. smegmatis, L-threose and L-altrose can be produced from cheap and abundant erythritol and D-fructose respectively, indicating that this enzyme has great potential for biological application in rare sugar production. Transcription analysis using various sugars revealed that this enzyme was significantly induced not only by L-arabinose and D-galactose but also by L-ribose, galactitol, L-ribulose, and L-talitol. This different result of transcription mediated by sugars from that of E. coli suggests that the transcriptional regulation of araA from M. smegmatis against sugar is loose compared with that from E. coli, and that it depends on the hydroxyl configuration at C2, C3 and C4 positions of sugars.

  12. Construction and characterization of regulated L-arabinose-inducible broad host range expression vectors in Xanthomonas.

    PubMed

    Sukchawalit, R; Vattanaviboon, P; Sallabhan, R; Mongkolsuk, S

    1999-12-15

    Several versions of broad host range (BHR), L-arabinose-inducible expression vectors were constructed. These expression vectors were based on a high copy number BHR pBBR1MCS-4 replicon that could replicate in both enteric and non-enteric Gram-negative bacteria. Two versions of expression cassettes containing multiple cloning sites either with or without a ribosome binding site were placed under transcriptional control of the Escherichia coli BAD promoter and araC gene. Three versions of vectors containing ampicillin or kanamycin or tetracycline resistance genes as selectable markers were constructed. In all six new L-arabinose-inducible BHR expression vectors containing many unique cloning sites, selectable markers were made to facilitate cloning and expression of genes in various Gram-negative bacteria. A Tn9 chloramphenicol acetyl transferase (cat) gene was cloned into an expression vector, resulting in pBBad18Acat that was used to establish optimal expression conditions (addition of 0.02% L-arabinose to mid-exponential phase cells for at least 1 h) in a Xanthomonas campestris pv. phaseoli. Comparison of the Cat enzyme activities between uninduced and a 180-min L-arabinose-induced culture showed a greater than 150-fold increased Cat specific activity. In addition, L-arabinose induction of exponential phase cells harboring pBBad18Acat gave a higher amount of Cat than similarly treated stationary phase cells. The usefulness of the expression vector was also demonstrated in both enteric and non-enteric Gram-negative bacteria.

  13. Identification and characterization of L-arabonate dehydratase, L-2-keto-3-deoxyarabonate dehydratase, and L-arabinolactonase involved in an alternative pathway of L-arabinose metabolism. Novel evolutionary insight into sugar metabolism.

    PubMed

    Watanabe, Seiya; Shimada, Naoko; Tajima, Kunihiko; Kodaki, Tsutomu; Makino, Keisuke

    2006-11-03

    Azospirillum brasiliense possesses an alternative pathway of L-arabinose metabolism, different from the known bacterial and fungal pathways. In the preceding articles, we identified and characterized L-arabinose-1-dehydrogenase and alpha-ketoglutaric semialdehyde dehydrogenase, which catalyzes the first and final reaction steps in this pathway, respectively (Watanabe, S., Kodaki, T., and Makino, K. (2006) J. Biol. Chem. 281, 2612-2623 and Watanabe, S., Kodaki, T., and Makino, K. (2006) J. Biol. Chem. 281, 28876-28888). We here report the remaining three enzymes, L-arabonate dehydratase, L-2-keto-3-deoxyarabonate (L-KDA) dehydratase, and L-arabinolactonase. N-terminal amino acid sequences of L-arabonate dehydratase and L-KDA dehydratase purified from A. brasiliense cells corresponded to those of AraC and AraD genes, which form a single transcriptional unit together with the L-arabinose-1-dehydrogenase gene. Furthermore, the L-arabinolactonase gene (AraB) was also identified as a component of the gene cluster. Genetic characterization of the alternative L-arabinose pathway suggested a significant evolutional relationship with the known sugar metabolic pathways, including the Entner-Doudoroff (ED) pathway and the several modified versions. L-arabonate dehydratase belongs to the ILVD/EDD family and spectrophotometric and electron paramagnetic resonance analysis revealed it to contain a [4Fe-4S](2+) cluster. Site-directed mutagenesis identified three cysteine ligands essential for cluster coordination. L-KDA dehydratase was sequentially similar to DHDPS/NAL family proteins. D-2-Keto-3-deoxygluconate aldolase, a member of the DHDPS/NAL family, catalyzes the equivalent reaction to L-KDA aldolase involved in another alternative L-arabinose pathway, probably associating a unique evolutional event between the two alternative L-arabinose pathways by mutation(s) of a common ancestral enzyme. Site-directed mutagenesis revealed a unique catalytic amino acid residue in L

  14. Genetic engineering and improvement of a Zymomonas mobilis for arabinose utilization and its performance on pretreated corn stover hydrolyzate

    DOE PAGES

    Chou, Yat -Chen; Linger, Jeffrey; Yang, Shihui; ...

    2015-04-28

    In this paper, a glucose, xylose and arabinose utilizing Zymomonas mobilis strain was constructed by incorporating arabinose catabolic pathway genes, araBAD encoding L-ribulokinase, L-arabinose isomerase and L-ribulose-5-phosphate- 4-epimerase in a glucose, xylose co-fermenting host, 8b, using a transposition integration approach. Further improvement on this arabinose-capable integrant, 33C was achieved by applying a second transposition to create a genomic knockout (KO) mutant library. Using arabinose as a sole carbon source and a selection pressure, the KO library was subjected to a growth-enrichment process involving continuous sub-culturing for over 120 generations. Strain 13-1-17, isolated from such process demonstrated significant improvement in metabolizingmore » arabinose in a dilute acid pretreated, saccharified corn stover slurry. Through Next Generation Sequencing (NGS) analysis, integration sites of the transposons were identified. Furthermore, multiple additional point mutations (SNPs: Single Nucleotide Polymorphisms) were discovered in 13-1-17, affecting genes araB and RpiB in the genome. Finally, we speculate that these mutations may have impacted the expression of the enzymes coded by these genes, ribulokinase and Ribose 5-P-isomerase, thus attributing to the improvement of the arabinose utilization.« less

  15. FORMATION OF FINE PARTICLES FROM RESIDUAL OIL COMBUSTION: REDUCING ULTRAFINE NUCLEI THROUGH THE ADDITION OF INORGANIC SORBENT

    EPA Science Inventory

    The paper gives results of an investigation, using an 82-kW-rated laboratory-scale refractory-lined combustor, of the characteristics of particulate matter emitted from residual oil combustion and the reduction of ultrafine nuclei by postflame sorbent injection. Without sorbent a...

  16. Biohydrogen production from arabinose and glucose using extreme thermophilic anaerobic mixed cultures

    PubMed Central

    2012-01-01

    Background Second generation hydrogen fermentation technologies using organic agricultural and forestry wastes are emerging. The efficient microbial fermentation of hexoses and pentoses resulting from the pretreatment of lingocellulosic materials is essential for the success of these processes. Results Conversion of arabinose and glucose to hydrogen, by extreme thermophilic, anaerobic, mixed cultures was studied in continuous (70°C, pH 5.5) and batch (70°C, pH 5.5 and pH 7) assays. Two expanded granular sludge bed (EGSB) reactors, Rarab and Rgluc, were continuously fed with arabinose and glucose, respectively. No significant differences in reactor performance were observed for arabinose and glucose organic loading rates (OLR) ranging from 4.3 to 7.1 kgCOD m-3 d-1. However, for an OLR of 14.2 kgCOD m-3 d-1, hydrogen production rate and hydrogen yield were higher in Rarab than in Rgluc (average hydrogen production rate of 3.2 and 2.0 LH2 L-1 d-1 and hydrogen yield of 1.10 and 0.75 molH2 mol-1substrate for Rarab and Rgluc, respectively). Lower hydrogen production in Rgluc was associated with higher lactate production. Denaturing gradient gel electrophoresis (DGGE) results revealed no significant difference on the bacterial community composition between operational periods and between the reactors. Increased hydrogen production was observed in batch experiments when hydrogen partial pressure was kept low, both with arabinose and glucose as substrate. Sugars were completely consumed and hydrogen production stimulated (62% higher) when pH 7 was used instead of pH 5.5. Conclusions Continuous hydrogen production rate from arabinose was significantly higher than from glucose, when higher organic loading rate was used. The effect of hydrogen partial pressure on hydrogen production from glucose in batch mode was related to the extent of sugar utilization and not to the efficiency of substrate conversion to hydrogen. Furthermore, at pH 7.0, sugars uptake, hydrogen production

  17. Evaluation of a peat moss plus soybean oil (PMSO) technology for reducing explosive residue transport to groundwater at military training ranges under field conditions.

    PubMed

    Fuller, Mark E; Schaefer, Charles E; Steffan, Robert J

    2009-11-01

    An evaluation of peat moss plus crude soybean oil (PMSO) for mitigation of explosive contamination of soil at military facilities was performed using large soil lysimeters under field conditions. Actual range soils were used, and two PMSO preparations with different ratios of peat moss:soybean oil (1:1, PO1; 1:2, PO2) were compared to a control lysimeter that received no PMSO. PMSO was applied as a 10 cm layer on top of the soil, and Composition B detonation residues from a 55-mm mortar round were applied at the surface of each of the lysimeters. Dissolution of the residues occurred during natural precipitation events over the course of 18 months. Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) emanating from the Composition B residues were significantly reduced by the PO2 PMSO material compared to the untreated control. Soil pore water RDX concentrations and RDX fluxes were reduced over 100-fold compared to the control plots at comparable depths. Residual RDX in the soil profile was also significantly lower in the PMSO treated plots. PO1 PMSO resulted in lower reductions in RDX transport than the PO2 PMSO. The transport of the RDX breakdown product hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine (MNX) was also greatly reduced by the PMSO materials. Results were in general agreement with a previously developed fate and transport model describing PMSO effectiveness. These results demonstrate the potential effectiveness of the inexpensive and environmentally benign PMSO technology for reducing the subsurface loading of explosives at training ranges and other military facilities.

  18. Elastic/plastic analyses of advanced composites investigating the use of the compliant layer concept in reducing residual stresses resulting from processing

    NASA Technical Reports Server (NTRS)

    Arnold, Steven M.; Arya, Vinod K.; Melis, Matthew E.

    1990-01-01

    High residual stresses within intermetallic and metal matrix composite systems can develop upon cooling from the processing temperature to room temperature due to the coefficient of thermal expansion (CTE) mismatch between the fiber and matrix. As a result, within certain composite systems, radial, circumferential, and/or longitudinal cracks have been observed to form at the fiber-matrix interface. The compliant layer concept (insertion of a compensating interface material between the fiber and matrix) was proposed to reduce or eliminate the residual stress buildup during cooling and thus minimize cracking. The viability of the proposed compliant layer concept is investigated both elastically and elastoplastically. A detailed parametric study was conducted using a unit cell model consisting of three concentric cylinders to determine the required character (i.e., thickness and material properties) of the compliant layer as well as its applicability. The unknown compliant layer mechanical properties were expressed as ratios of the corresponding temperature dependent Ti-24Al-11Nb (a/o) matrix properties. The fiber properties taken were those corresponding to SCS-6 (SiC). Results indicate that the compliant layer can be used to reduce, if not eliminate, radial and circumferential residual stresses within the fiber and matrix and therefore also reduce or eliminate the radial cracking. However, with this decrease in in-plane stresses, one obtains an increase in longitudinal stress, thus potentially initiating longitudinal cracking. Guidelines are given for the selection of a specific compliant material, given a perfectly bonded system.

  19. A novel L-arabinose-responsive regulator discovered in the rice-blast fungus Pyricularia oryzae (Magnaporthe oryzae).

    PubMed

    Klaubauf, Sylvia; Zhou, Miaomiao; Lebrun, Marc-Henri; de Vries, Ronald P; Battaglia, Evy

    2016-02-01

    In this study we identified the L-arabinose-responsive regulator of Pyricularia oryzae that regulates L-arabinose release and catabolism. Previously we identified the Zn2Cys6 transcription factor (TF), AraR, that has this role in the Trichocomaceae family (Eurotiales), but is absent in other fungi. Candidate Zn2Cys6 TF genes were selected according to their transcript profiles on L-arabinose. Deletion mutants of these genes were screened for their growth phenotype on L-arabinose. One mutant, named Δara1, was further analyzed. Our analysis demonstrated that Ara1 from P. oryzae is the functional analog of AraR from A. niger, while there is no significant sequence similarity between them.

  20. Fine-structure deletion map of the Escherichia coli L-arabinose operon.

    PubMed

    Schleif, R

    1972-11-01

    A fine-structure deletion map of the L-arabinose operon of E. coli was constructed by mapping deletion endpoints against point mutations. Of 350 independent deletions with average endpoint separation of ten nucleotides, 51 ended in the control region between the C and B genes, and the rest ended in the structural genes A, B, C, and D. If deletion endpoints are randomly distributed, the C and B genes are separated by about 510 nucleotides. Deletion endpoints and locations of point mutations in fact do appear randomly interspersed in the C and B genes, but no point mutations were found in the control region between them. Deletions were isolated with the aid of a heat-inducible lambda phage inserted into leucine genes adjacent to the arabinose genes. A high-capacity mating technique was developed for rapidly generating fine structure maps from many deletions and point mutations.

  1. The Bacillus subtilis L-arabinose (ara) operon: nucleotide sequence, genetic organization and expression.

    PubMed

    Sá-Nogueira, I; Nogueira, T V; Soares, S; de Lencastre, H

    1997-03-01

    The Bacillus subtilis L-arabinose metabolic genes araA, araB and araD, encoding L-arabinose isomerase, L-ribulokinase and L-ribulose-5-phosphate 4-epimerase, respectively, have been cloned previously and the products of araB and araD were shown to be functionally homologous to their Escherichia coli counterparts by complementation experiments. Here we report that araA, araB and araD, whose inactivation leads to an Ara- phenotype, are the first three ORFs of a nine cistron transcriptional unit with a total length of 11 kb. This operon, called ara, is located at about 256 degrees on the B. subtilis genetic map and contains six new genes named araL, araM, araN, araP, araQ and abfA. Expression of the ara operon is directed by a strong sigma A-like promoter identified within a 150 bp DNA fragment upstream from the translation start site of araA. Analysis of the sequence of the ara operon showed that the putative products of araN, araP and araQ are homologous to bacterial components of binding-protein-dependent transport systems and abfA most probably encodes an alpha-L-arabinofuranosidase. The functions of araL and araM are unknown. An in vitro-constructed insertion-deletion mutation in the region downstream from araD allowed us to demonstrate that araL, araM, araN, araP, araQ and abfA are not essential for L-arabinose utilization. Studies with strains bearing transcriptional fusions of the operon to the E. coli lacZ gene revealed that expression from the ara promoter is induced by L-arabinose and repressed by glucose.

  2. Mutations affecting catabolite repression of the L-arabinose regulon in Escherichia coli B/r.

    PubMed

    Heffernan, L; Bass, R; Englesberg, E

    1976-06-01

    Expression of the L-arabinose regulon in Escherichia coli B/r requires, among other things, cyclic adenosine-3', 5'-monophosphate (cAMP) and the cAMP receptor protein (CRP). Mutants deficient in adenyl cyclase (cya-), the enzyme which synthesizes cAMP, or CRP (crp-) are unable to utilize a variety of carbohydrates, including L-arabinose. Ara+ revertants of a cya-crp- strain were isolated on 0.2% minimal L-arabinose plates, conditions which require the entire ara regulon to be activated in the absence of cAMP and CRP. Evidence from genetic and physiological studies is consistent with placing these mutations in the araC regulatory gene. Deletion mapping with one mutant localized the site within either araO or araC, and complementation tests indicated the mutants acted trans to confer the ability to utilize L-arabinose in a cya-crp- genetic background. Since genetic analysis supports the conclusion, that the mutant sites are in the araC regulatory gene, the mutants were designated araCi, indicating a mutation in the regulatory gene affecting the cAMP-CRP requirement. Physiological analysis of one mutant, araCi1, illustrates the trans-acting nature of the mutation. In a cya-crp- genetic background, araCi1 promoted synthesis of both isomerase, a product of the araBAD operon, and permease, a product of the araE operon. Isomerase and permease levels in araCi1 cya+ crp+ were hyperinducible, and the sensitivity of each to cAMP was altered. Two models are presented that show the possible mutational lesion in the araCi strains.

  3. Boost the electron mobility of solution-grown organic single crystals via reducing the amount of polar solvent residues

    DOE PAGES

    Xue, Guobiao; Xin, Huolin L.; Wu, Jiake; ...

    2015-10-29

    Enhancing electron transport to match with the development in hole transport is critical for organic electronics in the future. As electron motion is susceptible to extrinsic factors, seeking these factors and avoiding their negative effects have become the central challenge. Here, the existence of polar solvent residues in solution-grown single-crystals of 6,13-bis(triisopropylsilylethynyl)-5,7,12,14-tetraazapentacene is identified as a factor detrimental to electron motion. Field-effect transistors of the crystals exhibit electron mobility boosted by about 60% after the residues are removed. The average electron mobility reaches up to 8.0 ± 2.2 cm2 V–1 s–1 with a highest value of 13.3 cm2 V–1 s–1;more » these results are significantly higher than those obtained previously for the same molecule (1.0–5.0 cm2 V–1 s–1). Furthermore, the achieved mobility is also higher than the maximum reported electron mobility for organic materials (11 cm2 V–1 s–1). As a result, this work should greatly accelerate the advancement of organic electron-transporting materials.« less

  4. High-affinity L-arabinose transport operon. Gene product expression and mRNAs.

    PubMed

    Horazdovsky, B F; Hogg, R W

    1987-09-05

    Various portions of the "high-affinity" L-arabinose transport operon were cloned into the plasmid expression vector pKK223-3 and the operon-encoded protein products were identified. The results indicate that three proteins are encoded by this operon. The first is a 33,000 Mr protein that is the product of the promoter-proximal L-arabinose binding protein coding sequence, araF. A 52,000 Mr protein is encoded by sequence 3' to araF and has been assigned to the araG locus. The sequence 3' to araG encodes a 31,000 Mr protein that has been assigned to the araH locus. Both the araG and araH gene products are localized in the membrane fraction of the cell, implying a role in the membrane-associated complex of the high-affinity L-arabinose transport system. Nuclease S1 protection studies indicate that two operon message populations are present in the cell, a full-length operon transcript and a seven- to tenfold more abundant binding protein-specific message. The relative abundance of these two message populations correlates with the differential expression of the binding protein and the membrane-associated proteins of the transport system.

  5. Induction of L-arabinose isomerase in gamma-irradiated Escherichia coli

    SciTech Connect

    Chatterjee, A.; Bhattacharya, A.K.

    1986-11-01

    Gamma irradiation of Escherichia coli B/r caused a dose-dependent inhibition of the capacity of the cells to synthesize L-arabinose isomerase in response to the inducer. At higher doses (18 krad and above), postirradiation incubation led to further inhibition of the capacity to synthesize L-arabinose isomerase, whereas cells receiving lower doses recovered from the damage to the enzyme synthesizing system following incubation. Cyclic AMP partially reversed the inhibitory effect on L-arabinose isomerase induction produced immediately after irradiation by all gamma-ray doses (up to 30 krad), but the enhanced inhibitory effect caused by induction in cells irradiated at higher doses could not be reversed by the nucleotide. It is suggested that although catabolite repression is partly responsible for causing the inhibition of the enzyme synthesizing capacity of the cells observed immediately after gamma irradiation, the enhanced inhibition caused by incubating cells irradiated at higher doses is not due to interference with the control mechanism regulated by catabolite repression.

  6. Characterisation of the arabinose-rich carbohydrate composition of immature and mature marama beans (Tylosema esculentum).

    PubMed

    Mosele, Minah M; Hansen, Ase S; Engelsen, Søren B; Diaz, Jerome; Sørensen, Iben; Ulvskov, Peter; Willats, William G T; Blennow, Andreas; Harholt, Jesper

    2011-08-01

    Marama bean (Tylosema esculentum) is an important component of the diet around the Kalahari Desert in Southern Africa where this drought resistant plant can grow. The marama bean contains roughly 1/3 proteins, 1/3 lipids and 1/3 carbohydrates, but despite its potential as dietary supplement little is known about the carbohydrate fraction. In this study the carbohydrate fraction of "immature" and "mature" marama seeds are characterised. The study shows that the marama bean contains negligible amounts of starch and soluble sugars, both far less than 1%. The cell wall is characterised by a high arabinose content and a high resistance to extraction as even a 6M NaOH extraction was insufficient to extract considerable amounts of the arabinose. The arabinose fraction was characterised by arabinan-like linkages and recognised by the arabinan antibody LM6 and LM13 indicating that it is pectic arabinan. Two pools of pectin could be detected; a regular CDTA (1,2-diaminocyclohexane-N,N,N',N'-tetraacetic acid) or enzymatically extractable pectin fraction and a recalcitrant pectin fraction containing the majority of the arabinans, of which about 40% was unextractable using 6M NaOH. Additionally, a high content of mannose was observed, possibly from mannosylated storage proteins.

  7. Structure of the effector-binding domain of the arabinose repressor AraR from Bacillus subtilis

    SciTech Connect

    Procházková, Kateřina; Čermáková, Kateřina; Pachl, Petr; Sieglová, Irena; Fábry, Milan; Otwinowski, Zbyszek; Řezáčová, Pavlína

    2012-02-01

    The crystal structure of the effector-binding domain of the transcriptional repressor AraR from B. subtilis in complex with the effector molecule (l-arabinose) was determined at 2.2 Å resolution. A detailed analysis of the crystal identified a dimer organization that is distinctive from that of other members of the GalR/LacI family. In Bacillus subtilis, the arabinose repressor AraR negatively controls the expression of genes in the metabolic pathway of arabinose-containing polysaccharides. The protein is composed of two domains of different phylogenetic origin and function: an N-terminal DNA-binding domain belonging to the GntR family and a C-terminal effector-binding domain that shows similarity to members of the GalR/LacI family. The crystal structure of the C-terminal effector-binding domain of AraR in complex with the effector l-arabinose has been determined at 2.2 Å resolution. The l-arabinose binding affinity was characterized by isothermal titration calorimetry and differential scanning fluorimetry; the K{sub d} value was 8.4 ± 0.4 µM. The effect of l-arabinose on the protein oligomeric state was investigated in solution and detailed analysis of the crystal identified a dimer organization which is distinctive from that of other members of the GalR/LacI family.

  8. Thermal-hydraulic processes involved in loss of residual heat removal during reduced inventory operation. Revision 1

    SciTech Connect

    Fletcher, C.D.; McHugh, P.R.; Naff, S.A.; Johnsen, G.W.

    1991-02-01

    This paper identifies the topics needed to understand pressurized water reactor response to an extended loss of residual heat removal event during refueling and maintenance outages. By identifying the possible plant conditions and cooling methods that would be used for each cooling mode, the controlling thermal-hydraulic processes and phenomena were identified. Controlling processes and phenomena include: gravity drain, core water boil-off, and reflux cooling processes. Important subcategories of the reflux cooling processes include: the initiation of reflux cooling from various plant conditions, the effects of air on reflux cooling, core level depression effects, issues regarding the steam generator secondaries, and the special case of boiler-condenser cooling with once-through steam generators. 25 refs., 6 figs., 1 tab.

  9. Reducing residual stresses and deformations in selective laser melting through multi-level multi-scale optimization of cellular scanning strategy

    NASA Astrophysics Data System (ADS)

    Mohanty, Sankhya; Hattel, Jesper H.

    2016-04-01

    Residual stresses and deformations continue to remain one of the primary challenges towards expanding the scope of selective laser melting as an industrial scale manufacturing process. While process monitoring and feedback-based process control of the process has shown significant potential, there is still dearth of techniques to tackle the issue. Numerical modelling of selective laser melting process has thus been an active area of research in the last few years. However, large computational resource requirements have slowed the usage of these models for optimizing the process. In this paper, a calibrated, fast, multiscale thermal model coupled with a 3D finite element mechanical model is used to simulate residual stress formation and deformations during selective laser melting. The resulting reduction in thermal model computation time allows evolutionary algorithm-based optimization of the process. A multilevel optimization strategy is adopted using a customized genetic algorithm developed for optimizing cellular scanning strategy for selective laser melting, with an objective of reducing residual stresses and deformations. The resulting thermo-mechanically optimized cellular scanning strategies are compared with standard scanning strategies and have been used to manufacture standard samples.

  10. D-Fucose as a gratuitous inducer of the L-arabinose operon in strains of Escherichia coli B-r mutant in gene araC.

    PubMed

    Beverin, S; Sheppard, D E; Park, S S

    1971-07-01

    d-Fucose, a nonmetabolizable analogue of l-arabinose, prevents growth of Escherichia coli B/r on a mineral salts medium plus l-arabinose by inhibiting induction of the l-arabinose operon. Mutations giving rise to d-fucose resistance map in gene araC and result in constitutive expression of the l-arabinose operon. Most of these mutations also permit d-fucose to serve as a gratuitous inducer. It is concluded that d-fucose-resistant mutants produce an araC gene product with an altered inducer specificity. Addition of l-arabinose to cells induced with the gratuitous inducer, d-fucose, resulted in severe transient repression of operon expression followed by permanent catabolite repression. Transient repression but no permanent catabolite repression was obtained when cells unable to metabolize l-arabinose were employed. It is concluded that transport of l-arabinose alone is sufficient to achieve transient repression of its own operon, but that metabolism of l-arabinose must occur to achieve permanent catabolite repression of the l-arabinose operon. This general effect has been termed "self-catabolite repression."

  11. A mixed diet supplemented with L-arabinose does not alter glycaemic or insulinaemic responses in healthy human subjects.

    PubMed

    Halschou-Jensen, Kia; Bach Knudsen, Knud E; Nielsen, Søren; Bukhave, Klaus; Andersen, Jens R

    2015-01-14

    In addition to a yet-to-be published study showing arabinose to have an inhibiting effect on maltase, in vitro studies have shown L-arabinose to exert an inhibiting effect on small-intestinal sucrase and maltase and the consumption of a sucrose-rich drink containing L-arabinose to exert positive effects on postprandial blood glucose, insulin and C-peptide responses in humans. However, the effects of adding L-arabinose to mixed meals on the indices of glucose control are unknown. The purpose of the present study was to investigate whether the positive effects of L-arabinose added to a sugar drink could be reproduced in subjects consuming a mixed meal containing sucrose and/or starch from wheat flour. A total of seventeen healthy men participated in study 1, a randomised, double-blind, cross-over trial. In this study, the subjects consumed two different breakfast meals containing sucrose and starch from wheat flour (meal A) or starch from wheat flour (meal B) supplemented with 0, 5 and 10 % L-arabinose by weight after a 12 h fast. A total of six healthy men participated in study 2, a randomised, double-blind, cross-over trial. In this study, the subjects also consumed meal B served in two different textures and a liquid meal with maltose supplemented with 0 and 20% L-arabinose. In addition, 1·5 g of paracetamol was chosen as an indirect marker to assess gastric emptying. Postprandial plasma glucose, insulin and C-peptide concentrations were measured regularly for 3 h. The results of the present study showed that the peak plasma concentration, time to reach peak plasma concentration or AUC values of glucose, insulin and C-peptide were not altered after consumption of the test meals. Overall, it was not possible to reproduce the beneficial effects of L-arabinose added to sucrose drinks when L-arabinose was mixed in a solid or semi-solid mixed meal.

  12. Structure of the effector-binding domain of the arabinose repressor AraR from Bacillus subtilis.

    PubMed

    Procházková, Kateřina; Cermáková, Kateřina; Pachl, Petr; Sieglová, Irena; Fábry, Milan; Otwinowski, Zbyszek; Rezáčová, Pavlína

    2012-02-01

    In Bacillus subtilis, the arabinose repressor AraR negatively controls the expression of genes in the metabolic pathway of arabinose-containing polysaccharides. The protein is composed of two domains of different phylogenetic origin and function: an N-terminal DNA-binding domain belonging to the GntR family and a C-terminal effector-binding domain that shows similarity to members of the GalR/LacI family. The crystal structure of the C-terminal effector-binding domain of AraR in complex with the effector L-arabinose has been determined at 2.2 Å resolution. The L-arabinose binding affinity was characterized by isothermal titration calorimetry and differential scanning fluorimetry; the K(d) value was 8.4 ± 0.4 µM. The effect of L-arabinose on the protein oligomeric state was investigated in solution and detailed analysis of the crystal identified a dimer organization which is distinctive from that of other members of the GalR/LacI family.

  13. Synthesis of arabinose glycosyl sulfamides as potential inhibitors of mycobacterial cell wall biosynthesis.

    PubMed

    Suthagar, Kajitha; Watson, Andrew J A; Wilkinson, Brendan L; Fairbanks, Antony J

    2015-09-18

    A series of arabinose glycosyl sulfamides with varying alkyl chain types and lengths were synthesised as mimics of decaprenolphosphoarabinose (DPA), and as potential inhibitors of mycobacterial cell wall biosynthesis. Unprecedented conversion of the desired furanose to the thermodynamically more stable pyranose form occurred during final de-protection. Biological testing against Mycobacterium smegmatis revealed low to moderate anti-mycobacterial activity with marked dependence on alkyl chain length, which in the case of mono-substituted sulfamides was maximal for a C-10 chain.

  14. Molecular regulation of arabinan and L-arabinose metabolism in Hypocrea jecorina (Trichoderma reesei).

    PubMed

    Akel, Eda; Metz, Benjamin; Seiboth, Bernhard; Kubicek, Christian P

    2009-12-01

    Hypocrea jecorina (anamorph: Trichoderma reesei) can grow on plant arabinans by the aid of secreted arabinan-degrading enzymes. This growth on arabinan and its degradation product L-arabinose requires the operation of the aldose reductase XYL1 and the L-arabinitol dehydrogenase LAD1. Growth on arabinan and L-arabinose is also severely affected in a strain deficient in the general cellulase and hemicellulase regulator XYR1, but this impairment can be overcome by constitutive expression of the xyl1 encoding the aldose reductase. An inspection of the genome of H. jecorina reveals four genes capable of degrading arabinan, i.e., the alpha-L-arabinofuranosidase encoding genes abf1, abf2, and abf3 and also bxl1, which encodes a beta-xylosidase with a separate alpha-L-arabinofuranosidase domain and activity but no endo-arabinanase. Transcriptional analysis reveals that in the parent strain QM9414 the expression of all of these genes is induced by L-arabinose and to a lesser extent by L-arabinitol and absent on D-glucose. Induction by L-arabinitol, however, is strongly enhanced in a Deltalad1 strain lacking L-arabinitol dehydrogenase activity and severely impaired in an aldose reductase (Deltaxyl1) strain, suggesting a cross talk between L-arabinitol and the aldose reductase XYL1 in an alpha-L-arabinofuranosidase gene expression. Strains bearing a knockout in the cellulase regulator xyr1 do not show any induction of abf2 and bxl1, and this phenotype cannot be reverted by constitutive expression of xyl1. The loss of function of xyr1 has also a slight effect on the expression of abf1 and abf3. We conclude that the expression of the four alpha-L-arabinofuranosidases of H. jecorina for growth on arabinan requires an early pathway intermediate (L-arabinitol or L-arabinose), the first enzyme of the pathway XYL1, and in the case of abf2 and bxl1 also the function of the cellulase regulator XYR1.

  15. Overexpression of hydroxynitrile lyase in cassava roots elevates protein and free amino acids while reducing residual cyanogen levels.

    PubMed

    Narayanan, Narayanan N; Ihemere, Uzoma; Ellery, Claire; Sayre, Richard T

    2011-01-01

    Cassava is the major source of calories for more than 250 million Sub-Saharan Africans, however, it has the lowest protein-to-energy ratio of any major staple food crop in the world. A cassava-based diet provides less than 30% of the minimum daily requirement for protein. Moreover, both leaves and roots contain potentially toxic levels of cyanogenic glucosides. The major cyanogen in cassava is linamarin which is stored in the vacuole. Upon tissue disruption linamarin is deglycosylated by the apolplastic enzyme, linamarase, producing acetone cyanohydrin. Acetone cyanohydrin can spontaneously decompose at pHs >5.0 or temperatures >35°C, or is enzymatically broken down by hydroxynitrile lyase (HNL) to produce acetone and free cyanide which is then volatilized. Unlike leaves, cassava roots have little HNL activity. The lack of HNL activity in roots is associated with the accumulation of potentially toxic levels of acetone cyanohydrin in poorly processed roots. We hypothesized that the over-expression of HNL in cassava roots under the control of a root-specific, patatin promoter would not only accelerate cyanogenesis during food processing, resulting in a safer food product, but lead to increased root protein levels since HNL is sequestered in the cell wall. Transgenic lines expressing a patatin-driven HNL gene construct exhibited a 2-20 fold increase in relative HNL mRNA levels in roots when compared with wild type resulting in a threefold increase in total root protein in 7 month old plants. After food processing, HNL overexpressing lines had substantially reduced acetone cyanohydrin and cyanide levels in roots relative to wild-type roots. Furthermore, steady state linamarin levels in intact tissues were reduced by 80% in transgenic cassava roots. These results suggest that enhanced linamarin metabolism contributed to the elevated root protein levels.

  16. Molecular characterization of a thermostable L-fucose isomerase from Dictyoglomus turgidum that isomerizes L-fucose and D-arabinose.

    PubMed

    Hong, Seung-Hye; Lim, Yu-Ri; Kim, Yeong-Su; Oh, Deok-Kun

    2012-09-01

    A recombinant thermostable l-fucose isomerase from Dictyoglomus turgidum was purified with a specific activity of 93 U/mg by heat treatment and His-trap affinity chromatography. The native enzyme existed as a 410 kDa hexamer. The maximum activity for l-fucose isomerization was observed at pH 7.0 and 80 °C with a half-life of 5 h in the presence of 1 mM Mn(2+) that was present one molecular per monomer. The isomerization activity of the enzyme with aldose substrates was highest for l-fucose (with a k(cat) of 15,500 min(-1) and a K(m) of 72 mM), followed by d-arabinose, d-altrose, and l-galactose. The 15 putative active-site residues within 5 Å of the substrate l-fucose in the homology model were individually replaced with other amino acids. The analysis of metal-binding capacities of these alanine-substituted variants revealed that Glu349, Asp373, and His539 were metal-binding residues, and His539 was the most influential residue for metal binding. The activities of all variants at 349 and 373 positions except for a dramatically decreased k(cat) of D373A were completely abolished, suggesting that Glu349 and Asp373 were catalytic residues. Alanine substitutions at Val131, Met197, Ile199, Gln314, Ser405, Tyr451, and Asn538 resulted in substantial increases in K(m), suggesting that these amino acids are substrate-binding residues. Alanine substitutions at Arg30, Trp102, Asn404, Phe452, and Trp510 resulted in decreases in k(cat), but had little effect on K(m).

  17. Assessment of some straw-derived materials for reducing the leaching potential of Metribuzin residues in the soil

    NASA Astrophysics Data System (ADS)

    Cara, Irina Gabriela; Trincă, Lucia Carmen; Trofin, Alina Elena; Cazacu, Ana; Ţopa, Denis; Peptu, Cătălina Anişoara; Jităreanu, Gerard

    2015-12-01

    Biomass (straw waste) can be used as raw to obtain materials for herbicide removal from wastewater. These by-products have some important advantages, being environmentally friendly, easily available, presenting low costs, and requiring little processing to increase their adsorptive capacity. In the present study, some materials derived from agricultural waste (wheat, corn and soybean straw) were investigated as potential adsorbents for metribuzin removal from aqueous solutions. The straw wastes were processed by grinding, mineralisation (850 °C) and KOH activation in order to improve their functional surface activity. The materials surface characteristics were investigated by scanning electron microscopy, energy dispersive X-ray spectroscopy and atomic force microscopy. The adsorbents capacity was evaluated using batch sorption tests and liquid chromatography coupled with mass spectrometry for herbicide determination. For adsorption isotherms, the equilibrium time considered was 3 h. The experimental adsorption data were modelled by Freundlich and Langmuir models. The activated straw and ash-derived materials from wheat, corn and soybean increased the adsorption capacity of metribuzin with an asymmetrical behaviour. Overall, our results sustain that activated ash-derived from straw and activated straw materials can be a valuable solution for reducing the leaching potential of metribuzin through soil.

  18. Identifying the key factors in increasing recycling and reducing residual household waste: a case study of the Flemish region of Belgium.

    PubMed

    Gellynck, X; Jacobsen, R; Verhelst, P

    2011-10-01

    The competent waste authority in the Flemish region of Belgium created the 'Implementation plan household waste 2003-2007' and the 'Implementation plan sustainable management 2010-2015' to comply with EU regulation. It incorporates European and regional requirements and describes strategies, goals, actions and instruments for the collection and treatment of household waste. The central mandatory goal is to reduce and maintain the amount of residual household waste to 150 kg per capita per year between 2010-2015. In literature, a reasonable body of information has been published on the effectiveness and efficiency of a variety of policy instruments, but the information is complex, often contradictory and difficult to interpret. The objective of this paper is to identify, through the development of a binary logistic regression model, those variables of the waste collection scheme that help municipalities to reach the mandatory 150 kg goal. The model covers a number of variables for household characteristics, provision of recycling services, frequency of waste collection and charging for waste services. This paper, however, is not about waste prevention and reuse. The dataset originates from 2003. Four out of 12 variables in the model contributed significantly: income per capita, cost of residual waste collection, collection frequency and separate curbside collection of organic waste.

  19. Production of L-arabinose from corn hull arabinoxylan by Arthrobacter aurescens MK5 α-L-arabinofuranosidase.

    PubMed

    Kurakake, Masahiro; Takao, Jyunpei; Asano, Osamu; Tanimoto, Hiroko; Komaki, Toshiaki

    2011-03-01

    Arabinoxylans, which are comprised of a xylan backbone to which are attached glycosyl units that are primarily L-arabinofuranosyl units, are ubiquitous among plant species where it is a constituent of the cell wall. Arabinoxylan has attracted much attention as a potential biomass resource and L-arabinose has recently been reported to possess functional properties that are effective in the treatment of diabetes. Here, we report an α-L-arabinofuranohydrolase, isolated from the soil microbe Arthrobacter aurescens strain MK5, effective in releasing L-arabinose from corn hull arabinoxylan. When A. aurescens strain MK5 was grown in a liquid medium, corn hull arabinoxylan, which has a higher arabinose content (Ara/Xyl = 0.6) than oat spelts xylan (Ara/Xyl = 0.12), induced more efficient arabinoxylan hydrolase production. Analysis of enzyme activity in the culture broth revealed that arabinoxylan hydrolase activity was high, and α-L-arabinofuranosidase and β-xylosidase activities were low. The optimum pH of the MK5 arabinoxylan hydrolase at 40 °C was around 7 and enzyme activity was relatively stable at an alkaline pH up to 9.5. The optimum temperature at pH 7 was around 50 °C and enzyme activity was stable under 50 °C. During the hydrolysis of corn hull arabinoxylan, only L-arabinose was released and 45.1% maximum sugar recovery was achieved. The A. aurescens MK5 enzyme was a typical arabinoxylan α-L-arabinofuranohydrolase and was most effective at releasing L-arabinose from corn hull arabinoxylan, which has a high arabinose content. This enzyme may have important industrial applications.

  20. Use of the arabinose p(bad) promoter for tightly regulated display of proteins on bacteriophage.

    PubMed

    Huang, W; McKevitt, M; Palzkill, T

    2000-06-27

    Phage display is a widely used method to optimize the binding characteristics of protein-ligand interactions. In addition, it has been used to clone genes from genomic and cDNA libraries based on their ligand-binding characteristics. One difficulty often encountered when expressing heterologous proteins by phage display is the toxicity of the protein on the Escherichia coli host. Previous studies have shown that heterologous protein expression can be tightly controlled using plasmids with the P(BAD) promoter of the arabinose operon of E. coli, and the araC gene, which is both a positive and negative regulator of the promoter. We constructed a set of phage display vectors that utilize the P(BAD) promoter to control the expression of proteins on the surface of the M13 bacteriophage. These vectors exhibit tightly controlled expression of proteins on the surface of the phage. In addition, the amount of protein displayed on the phage is modulated by the amount of arabinose present in the growth medium during phage propagation. This may be useful for altering the stringency of binding enrichment during phage display.

  1. Structural analysis of arabinose-5-phosphate isomerase from Bacteroides fragilis and functional implications.

    PubMed

    Chiu, Hsiu Ju; Grant, Joanna C; Farr, Carol L; Jaroszewski, Lukasz; Knuth, Mark W; Miller, Mitchell D; Elsliger, Marc André; Deacon, Ashley M; Godzik, Adam; Lesley, Scott A; Wilson, Ian A

    2014-10-01

    The crystal structure of arabinose-5-phosphate isomerase (API) from Bacteroides fragilis (bfAPI) was determined at 1.7 Å resolution and was found to be a tetramer of a single-domain sugar isomerase (SIS) with an endogenous ligand, CMP-Kdo (cytidine 5'-monophosphate-3-deoxy-D-manno-oct-2-ulosonate), bound at the active site. API catalyzes the reversible isomerization of D-ribulose 5-phosphate to D-arabinose 5-phosphate in the first step of the Kdo biosynthetic pathway. Interestingly, the bound CMP-Kdo is neither the substrate nor the product of the reaction catalyzed by API, but corresponds to the end product in the Kdo biosynthetic pathway and presumably acts as a feedback inhibitor for bfAPI. The active site of each monomer is located in a surface cleft at the tetramer interface between three monomers and consists of His79 and His186 from two different adjacent monomers and a Ser/Thr-rich region, all of which are highly conserved across APIs. Structure and sequence analyses indicate that His79 and His186 may play important catalytic roles in the isomerization reaction. CMP-Kdo mimetics could therefore serve as potent and specific inhibitors of API and provide broad protection against many different bacterial infections.

  2. Structural analysis of arabinose-5-phosphate isomerase from Bacteroides fragilis and functional implications

    PubMed Central

    Chiu, Hsiu-Ju; Grant, Joanna C.; Farr, Carol L.; Jaroszewski, Lukasz; Knuth, Mark W.; Miller, Mitchell D.; Elsliger, Marc-André; Deacon, Ashley M.; Godzik, Adam; Lesley, Scott A.; Wilson, Ian A.

    2014-01-01

    The crystal structure of arabinose-5-phosphate isomerase (API) from Bacteroides fragilis (bfAPI) was determined at 1.7 Å resolution and was found to be a tetramer of a single-domain sugar isomerase (SIS) with an endogenous ligand, CMP-Kdo (cytidine 5′-monophosphate-3-deoxy-d-manno-oct-2-ulosonate), bound at the active site. API catalyzes the reversible isomerization of d-ribulose 5-phosphate to d-arabinose 5-phosphate in the first step of the Kdo biosynthetic pathway. Interestingly, the bound CMP-Kdo is neither the substrate nor the product of the reaction catalyzed by API, but corresponds to the end product in the Kdo biosynthetic pathway and presumably acts as a feedback inhibitor for bfAPI. The active site of each monomer is located in a surface cleft at the tetramer interface between three monomers and consists of His79 and His186 from two different adjacent monomers and a Ser/Thr-rich region, all of which are highly conserved across APIs. Structure and sequence analyses indicate that His79 and His186 may play important catalytic roles in the isomerization reaction. CMP-Kdo mimetics could therefore serve as potent and specific inhibitors of API and provide broad protection against many different bacterial infections. PMID:25286848

  3. Computer simulation of protein—carbohydrate complexes: application to arabinose-binding protein and pea lectin

    NASA Astrophysics Data System (ADS)

    Rao, V. S. R.; Biswas, Margaret; Mukhopadhyay, Chaitali; Balaji, P. V.

    1989-03-01

    The CCEM method (Contact Criteria and Energy Minimisation) has been developed and applied to study protein-carbohydrate interactions. The method uses available X-ray data even on the native protein at low resolution (above 2.4 Å) to generate realistic models of a variety of proteins with various ligands. The two examples discussed in this paper are arabinose-binding protein (ABP) and pea lectin. The X-ray crystal structure data reported on ABP-β- L-arabinose complex at 2.8, 2.4 and 1.7 Å resolution differ drastically in predicting the nature of the interactions between the protein and ligand. It is shown that, using the data at 2.4 Å resolution, the CCEM method generates complexes which are as good as the higher (1.7 Å) resolution data. The CCEM method predicts some of the important hydrogen bonds between the ligand and the protein which are missing in the interpretation of the X-ray data at 2.4 Å resolution. The theoretically predicted hydrogen bonds are in good agreement with those reported at 1.7 Å resolution. Pea lectin has been solved only in the native form at 3 Å resolution. Application of the CCEM method also enables us to generate complexes of pea lectin with methyl-α- D-glucopyranoside and methyl-2,3-dimethyl-α- D-glucopyranoside which explain well the available experimental data in solution.

  4. Genetic and biochemical characterization of D-arabinose dehydrogenase from Neurospora crassa.

    PubMed Central

    Carrasco, A; Pincheira, G; Ureta, T

    1981-01-01

    D-Arabinose dehydrogenase has been purified to homogeneity from wild-type Neurospora crassa 74-A (FGSC 262) and from two colonial mutants, col-15a (FGSC 1391) and col-16a (FGSC 1349), found to contain more of the enzyme. The enzymes were characterized by measurement of several kinetic and physicochemical parameters. The enzymes were the same in all characteristics studied thus far. Immunological studied performed with enzyme preparations from the three strains showed antigenic identity and indicated that those colonial strains contain more normal enzyme, rather than the usual amount of an altered "improved" enzyme. Quantitation of the enzyme in crude extracts, performed by single radial immunodiffusion, showed that the colonial strains have twice the level of enzyme as the wild-type strain. Genetic characterization, performed by analysis of meiotic products, heterokaryosis, and reversions, indicated that the difference in D-arabinose dehydrogenase activity detected among the three strains is probably determined by one gene. The genetic control, structural or regulatory of this enzyme activity is different from that determining the morphological alterations exhibited by mutant strains carrying the col-15 or col-16 gene. Images PMID:6450742

  5. Urea Hydrogen Peroxide Reduces the Numbers of Lactobacilli, Nourishes Yeast, and Leaves No Residues in the Ethanol Fermentation

    PubMed Central

    Narendranath, N. V.; Thomas, K. C.; Ingledew, W. M.

    2000-01-01

    Urea hydrogen peroxide (UHP) at a concentration of 30 to 32 mmol/liter reduced the numbers of five Lactobacillus spp. (Lactobacillus plantarum, L. paracasei, Lactobacillus sp. strain 3, L. rhamnosus, and L. fermentum) from ∼107 to ∼102 CFU/ml in a 2-h preincubation at 30°C of normal-gravity wheat mash at ∼21 g of dissolved solids per ml containing normal levels of suspended grain particles. Fermentation was completed 36 h after inoculation of Saccharomyces cerevisiae in the presence of UHP, even when wheat mash was deliberately contaminated (infected) with L. paracasei at ∼107 CFU/ml. There were no significant differences in the maximum ethanol produced between treatments when urea hydrogen peroxide was used to kill the bacteria and controls (in which no bacteria were added). However, the presence of L. paracasei at ∼107 CFU/ml without added agent resulted in a 5.84% reduction in the maximum ethanol produced compared to the control. The bactericidal activity of UHP is greatly affected by the presence of particulate matter. In fact, only 2 mmol of urea hydrogen peroxide per liter was required for disinfection when mashes had little or no particulate matter present. No significant differences were observed in the decomposition of hydrogen peroxide in normal-gravity wheat mash at 30°C whether the bactericidal agent was added as H2O2 or as urea hydrogen peroxide. NADH peroxidase activity (involved in degrading H2O2) increased significantly (P = 0.05) in the presence of 0.75 mM hydrogen peroxide (sublethal level) in all five strains of lactobacilli tested but did not persist in cells regrown in the absence of H2O2. H2O2-resistant mutants were not expected or found when lethal levels of H2O2 or UHP were used. Contaminating lactobacilli can be effectively managed by UHP, a compound which when used at ca. 30 mmol/liter happens to provide near-optimum levels of assimilable nitrogen and oxygen that aid in vigorous fermentation performance by yeast. PMID:11010858

  6. Analysis of the arabinose-5-phosphate isomerase of Bacteroides fragilis provides insight into regulation of single-domain arabinose phosphate isomerases.

    PubMed

    Cech, David; Wang, Pan Fen; Holler, Tod P; Woodard, Ronald W

    2014-08-01

    Arabinose-5-phosphate isomerases (APIs) catalyze the interconversion of d-ribulose-5-phosphate and D-arabinose-5-phosphate, the first step in the biosynthesis of 3-deoxy-D-manno-octulosonic acid (Kdo), an essential component of the lipopolysaccharide in Gram-negative bacteria. Classical APIs, such as Escherichia coli KdsD, contain a sugar isomerase domain and a tandem cystathionine beta-synthase domain. Despite substantial effort, little is known about structure-function relationships in these APIs. We recently reported an API containing only a sugar isomerase domain. This protein, c3406 from E. coli CFT073, has no known physiological function. In this study, we investigated a putative single-domain API from the anaerobic Gram-negative bacterium Bacteroides fragilis. This putative API (UniProt ID Q5LIW1) is the only protein encoded by the B. fragilis genome with significant identity to any known API, suggesting that it is responsible for lipopolysaccharide biosynthesis in B. fragilis. We tested this hypothesis by preparing recombinant Q5LIW1 protein (here referred to by the UniProt ID Q5LIW1), characterizing its API activity in vitro, and demonstrating that the gene encoding Q5LIW1 (GenBank ID YP_209877.1) was able to complement an API-deficient E. coli strain. We demonstrated that Q5LIW1 is inhibited by cytidine 5'-monophospho-3-deoxy-D-manno-2-octulosonic acid, the final product of the Kdo biosynthesis pathway, with a Ki of 1.91 μM. These results support the assertion that Q5LIW1 is the API that supports lipopolysaccharide biosynthesis in B. fragilis and is subject to feedback regulation by CMP-Kdo. The sugar isomerase domain of E. coli KdsD, lacking the two cystathionine beta-synthase domains, demonstrated API activity and was further characterized. These results suggest that Q5LIW1 may be a suitable system to study API structure-function relationships.

  7. Metabolite gene regulation: imidazole and imidazole derivatives which circumvent cyclic adenosine 3',5'-monophosphate in induction of the Escherichia coli L-arabinose operon.

    PubMed

    Kline, E L; Bankaitis, V A; Brown, C S; Montefiori, D C

    1980-02-01

    Imidazole, histidine, histamine, histidinol phosphate, urocanic acid, or imidazolepropionic acid were shown to induce the L-arabinose operon in the absence of cyclic adenosine 3',5'-monophosphate. Induction was quantitated by measuring the increased differential rate of synthesis of L-arabinose isomerase in Escherichia coli strains which carried a deletion of the adenyl cyclase gene. The crp gene product (cyclic adenosine 3',5'-monophosphate receptor protein) and the araC gene product (P2) were essential for induction of the L-arabinose operon by imidazole and its derivatives. These compounds were unable to circumvent the cyclic adenosine 3',5'-monophosphate in the induction of the lactose or the maltose operons. The L-arabinose regulon was catabolite repressed upon the addition of glucose to a strain carrying an adenyl cyclase deletion growing in the presence of L-arabinose with imidazole. These results demonstrated that several imidazole derivatives may be involved in metabolite gene regulation (23).

  8. The residual and direct effects of reduced-risk and conventional miticides on twospotted spider mites, Tetranychus urticae (Acari: Tetranychidae) and predatory mites (Acari: Phytoseiidae)

    SciTech Connect

    Liburd, O.E.; White, J.C.; Rhodes, E.M.; Browdy, A.A.

    2007-03-15

    The residual effects of several reduced-risk and conventional miticides were evaluated in strawberries (Fragaria z ananassa Duchesne) on the twospotted spider mite (TSSM), Tetranychus urticae Koch (Acari: Tetranychidae) and on 2 predatory mites, Neoseiulus californicus McGregor and Phytoseiulus persimilis Athias-Henriot (Acari: Phytoseiidae). Experiments were conducted in the laboratory and greenhouse. The greenhouse experiments also tested the direct effects of the miticides on TSSM. The efficacy of conventional and reduced-risk miticides was evaluated on strawberry leaf discs and on whole plants for control of TSSM. Furthermore, the residual effects of these miticides were evaluated on whole strawberry plants against selective predatory mites. For TSSM, 5 treatments were evaluated: a conventional miticide; fenbutatin-oxide (Vendex[reg]) and 3 reduced-risk miticides; binfenazate (Acramite 50WP[reg]), activated garlic extract (Repel[reg]), sesame seed and castor oil (Wipeout[reg]), and a water-treated control. For predatory mites, the residual effects of only Acramite[reg] and Vendex[reg] were evaluated. Acramite[reg] was the most effective acaricide in reducing TSSM populations in both the laboratory and greenhouse experiments. Vendex[reg] and Wipeout[reg] were also effective in the laboratory, but did not cause significant reduction of TSSM in the greenhouse. Repel[reg] was the least effective of the 4 pesticides evaluated. Neither Acramite[reg] nor Vendex[reg] had a significant effect on either predatory mite species. However, there appeared to be more predatory mites on the Vendex[reg]-treated plants than on the Acramite[reg]-treated plants. There were significantly more predatory mites of both species on the cue plants, which were inoculated with TSSM versus the non-cue plants, which were not inoculated. (author) [Spanish] Los efectos residuales en poblaciones de la 'arana roja', Tetranychus urticae Koch (Acari: Tetranichidae) y de los acaros predadores

  9. Occurrence of complex type free N-glycans with a single GlcNAc residue at the reducing termini in the fresh-water plant, Egeria densa.

    PubMed

    Maeda, Megumi; Ebara, Natsuki; Tani, Misato; Vavricka, Christopher J; Kimura, Yoshinobu

    2017-04-01

    In our previous study, we found unique free N-glycans (FNGs), which carry a single GlcNAc residue (GN1) at the reducing-end side and the Lewis-a epitope at the non-reducing-end side, in the culture broth of rice cells. Based on the FNG structural features and the substrate specificity of plant ENGase, we hypothesized that there might be a novel biosynthetic mechanism responsible for the production of these unique GN1-FNGs, in which high-mannose type (HMT)-GN1-FNGs produced in the cytosol from misfolded glycoproteins by ENGase are transported back into the endoplasmic reticulum and processed to plant complex type (PCT)-GN1-FNGs in the Golgi apparatus. Until now, however, PCT-GN1-FNGs had only been found in the culture broth of rice cultured cells and never in plants, suggesting that the formation of PCT-GN1-FNGs might be generated under special or artificial conditions. In this study, we confirm the presence of PCT-GN1-FNGs, HMT-GN1-FNGs and PCT-GN2-FNGs in the fresh-water plant Egeria densa. These results suggest that a mechanism responsible for the production of PCT-GN1-FNG is present in native plant tissues.

  10. Reverse-polynomial dilution calibration methodology extends lower limit of quantification and reduces relative residual error in targeted peptide measurements in blood plasma.

    PubMed

    Yau, Yunki Y; Duo, Xizi; Leong, Rupert W L; Wasinger, Valerie C

    2015-02-01

    Matrix effect is the alteration of an analyte's concentration-signal response caused by co-existing ion components. With electrospray ionization (ESI), matrix effects are believed to be a function of the relative concentrations, ionization efficiency, and solvation energies of the analytes within the electrospray ionization droplet. For biological matrices such as plasma, the interactions between droplet components is immensely complex and the effect on analyte signal response not well elucidated. This study comprised of three sequential quantitative analyses: we investigated whether there is a generalizable correlation between the range of unique ions in a sample matrix (complexity); the amount of matrix components (concentration); and matrix effect, by comparing an E. coli digest matrix (∼2600 protein proteome) with phospholipid depleted human blood plasma, and unfractionated, nondepleted human plasma matrices (∼10(7) proteome) for six human plasma peptide multiple reaction monitoring assays. Our data set demonstrated analyte-specific interactions with matrix complexity and concentration properties resulting in significant ion suppression for all peptides (p < 0.01), with nonuniform effects on the ion signals of the analytes and their stable-isotope analogs. These matrix effects were then assessed for translation into relative residual error and precision effects in a low concentration (∼0-250 ng/ml) range across no-matrix, complex matrix, and highly complex matrix, when a standard addition stable isotope dilution calibration method was used. Relative residual error (%) and precision (CV%) by stable isotope dilution were within <20%; however, error in phospholipid-depleted and nondepleted plasma matrices were significantly higher compared with no-matrix (p = 0.006). Finally a novel reverse-polynomial dilution calibration method with and without phospholipid-depletion was compared with stable isotope dilution for relative residual error and precision

  11. An encodable lanthanide binding tag with reduced size and flexibility for measuring residual dipolar couplings and pseudocontact shifts in large proteins

    PubMed Central

    Barb, Adam W.; Subedi, Ganesh P.

    2016-01-01

    Metal ions serve important roles in structural biology applications from long-range perturbations seen in magnetic resonance experiments to electron-dense signatures in x-ray crystallography data; however, the metal ion must be secured in a molecular framework to achieve the maximum benefit. Polypeptide-based lanthanide-binding tags (LBTs) represent one option that can be directly encoded within a recombinant protein expression construct. However, LBTs often exhibit significant mobility relative to the target molecule. Here we report the characterization of improved LBTs sequences for insertion into a protein loop. These LBTs were inserted to connect two parallel alpha helices of an immunoglobulin G (IgG)-binding Z domain platform. Variants A and B bound Tb3+ with high affinity (0.70 and 0.13 µM, respectively) and displayed restricted LBT motion. Compared to the parent construct, the metal-bound A experienced a 2.5-fold reduction in tag motion as measured by magnetic field-induced residual dipolar couplings and was further studied in a 72.2 kDa complex with the human IgG1 fragment crystallizable (IgG1 Fc) glycoprotein. The appearance of both pseudo-contact shifts (-0.221 to 0.081 ppm) and residual dipolar couplings (-7.6 to 14.3 Hz) of IgG1 Fc resonances in the IgG1 Fc:(variant A:Tb3+)2 complex indicated structural restriction of the LBT with respect to the Fc. These studies highlight the applicability of improved LBT sequences with reduced mobility to probe the structure of macromolecular systems. PMID:26728077

  12. Product PCNPsurv or the "reduced" evaporation residue cross section σER/σfusion for "hot" fusion reactions studied with the dynamical cluster-decay model

    NASA Astrophysics Data System (ADS)

    Chopra, Sahila; Kaur, Arshdeep; Hemdeep, Gupta, Raj K.

    2016-04-01

    The product PCNPsurv of compound nucleus (CN) fusion probability PCN and survival probability Psurv is calculated to determine the reduced evaporation residue cross section σER/σfusion , denoted σERreduced, with (total) fusion cross section σfusion given as a sum of CN-formation cross section σCN and non-CN cross section σnCN for each reaction, where σCN is the sum of evaporation residue cross section σER and fusion-fission cross section σff and σnCN, if not measured, is estimated empirically as the difference between measured and calculated σfusion. Our calculations of PCN and Psurv, based on the dynamical cluster-decay model, were successfully made for some 17 "hot" fusion reactions, forming different CN of mass numbers ACN˜100 -300 , with deformations of nuclei up to hexadecapole deformations and "compact" orientations for both coplanar (Φc=0∘ ) and noncoplanar (Φc≠0∘ ) configurations, using various different nuclear interaction potentials. Interesting variations of σERreduced with CN excitation energy E*, fissility parameter χ , CN mass ACN, and Coulomb parameter Z1Z2 show that, independent of entrance channel, different isotopes of CN, and nuclear interaction potentials used, the dominant quantity in the product is Psurv, which classifies all the studied CN into three groups of weakly fissioning, radioactive, and strongly fissioning superheavy nuclei, with relative magnitudes of σERreduced˜1 , ˜10-6 , and ˜10-11 , which, like for PCN, get further grouped in two dependencies of (i) weakly fissioning and strongly fissioning superheavy nuclei decreasing with increasing E* and (ii) radioactive nuclei increasing with increasing E*.

  13. An encodable lanthanide binding tag with reduced size and flexibility for measuring residual dipolar couplings and pseudocontact shifts in large proteins.

    PubMed

    Barb, Adam W; Subedi, Ganesh P

    2016-01-01

    Metal ions serve important roles in structural biology applications from long-range perturbations seen in magnetic resonance experiments to electron-dense signatures in X-ray crystallography data; however, the metal ion must be secured in a molecular framework to achieve the maximum benefit. Polypeptide-based lanthanide-binding tags (LBTs) represent one option that can be directly encoded within a recombinant protein expression construct. However, LBTs often exhibit significant mobility relative to the target molecule. Here we report the characterization of improved LBTs sequences for insertion into a protein loop. These LBTs were inserted to connect two parallel alpha helices of an immunoglobulin G (IgG)-binding Z domain platform. Variants A and B bound Tb(3+) with high affinity (0.70 and 0.13 μM, respectively) and displayed restricted LBT motion. Compared to the parent construct, the metal-bound A experienced a 2.5-fold reduction in tag motion as measured by magnetic field-induced residual dipolar couplings and was further studied in a 72.2 kDa complex with the human IgG1 fragment crystallizable (IgG1 Fc) glycoprotein. The appearance of both pseudo-contact shifts (-0.221 to 0.081 ppm) and residual dipolar couplings (-7.6 to 14.3 Hz) of IgG1 Fc resonances in the IgG1 Fc:(variant A:Tb(3+))2 complex indicated structural restriction of the LBT with respect to the Fc. These studies highlight the applicability of improved LBT sequences with reduced mobility to probe the structure of macromolecular systems.

  14. Industrial Saccharomyces cerevisiae Yeast Strain Engineered to Convert Glucose, Mannose, Arabinose, and Xylose (GMAX) to Ethanol Anaerobically

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Technology for engineering an industrial yeast strain for production of ethanol from glucose, mannose, arabinose, and xylose (GMAX-yeast) using both corn starch and cellulosic feedstocks with simultaneous production of valuable coproducts, including biodiesel, will be discussed. A stable industrial...

  15. Isolation and identification of arabinose mycolates of Cell Wall Skeleton (CWS) derived from Mycobacterium bovis BCG Tokyo 172 (SMP-105).

    PubMed

    Uenishi, Yuko; Kusunose, Naoto; Yano, Ikuya; Sunagawa, Makoto

    2010-03-01

    A unique hydrolysis method using a two-layer solution, consisting of diluted hydrochloric acid and toluene was developed to isolate whole arabinose mycolates from the cell wall skeleton of Mycobacterium bovis BCG Tokyo 172 (SMP-105) in order to reveal its pivotal role in enhancing immune responses against tumors.

  16. Transcriptional control in the L-arabinose operon of Escherichia coli B-r.

    PubMed

    Cleary, P P; Englesberg, E

    1974-04-01

    The structural genes involved in l-arabinose metabolism are regulated by the protein product of the araC gene. This protein functions as both an activator and repressor of enzyme synthesis in this gene complex. Using lambdah80dara deoxyribonucleic acid in hybridization studies, we have shown that the ara operon, including structural genes araB, araA, and araD, is transcribed in the direction araB to araD and that initiation of transcription of these genes requires an active araC gene. The half-life of this message, approximately 3 min at 30 C, is the same in the presence or absence of the araC protein in the activator state. However, an unexplained 2-min lag in decay of ara messenger ribonucleic acid that does not occur in decay of lac messenger ribonucleic acid is observed. This lag period requires activated araC protein.

  17. Performance testing of Zymomonas mobilis metabolically engineered for cofermentation of glucose, xylose, and arabinose.

    PubMed

    Lawford, Hugh G; Rousseau, Joyce D

    2002-01-01

    IOGEN Corporation of Ottawa, Canada, has recently built a 40t/d biomass-to-ethanol demonstration plant adjacent to its enzyme production facility. It has partnered with the University of Toronto to test the C6/C5 cofermenta-tion performance characteristics of the National Renewable Energy Labora-tory's metabolically engineered Zymomonas mobilis using various biomass hydrolysates. IOGEN's feedstocks are primarily agricultural wastes such as corn stover and wheat straw. Integrated recombinant Z. mobilis strain AX101 grows on D-xylose and/or L-arabinose as the sole carbon/energy sources and ferments these pentose sugars to ethanol in high yield. Strain AX101 lacks the tetracycline resistance gene that was a common feature of other recombinant Zm constructs. Genomic integration provides reliable cofermentation performance in the absence of antibiotics, another characteristic making strain AX101 attractive for industrial cellulosic ethanol production. In this work, IOGEN's biomass hydrolysate was simulated by a pure sugar medium containing 6% (w/v) glucose, 3% xylose, and 0.35% arabinose. At a level of 3 g/L (dry solids), corn steep liquor with inorganic nitrogen (0.8 g/L of ammonium chloride or 1.2 g/L of diammonium phosphate) was a cost-effective nutritional supplement. In the absence of acetic acid, the maximum volumetric ethanol productivity of a continuous fermentation at pH 5.0 was 3.54 g/L x h. During prolonged continuous fermentation, the efficiency of sugar-to-ethanol conversion (based on total sugar load) was maintained at >85%. At a level of 0.25% (w/v) acetic acid, the productivity decreased to 1.17 g/L x h at pH 5.5. Unlike integrated, xylose-utilizing rec Zm strain C25, strain AX101 produces less lactic acid as byproduct, owing to the fact that the Escherichia coli arabinose genes are inserted into a region of the host chromosome tentatively assigned to the gene for D-lactic acid dehydrogenase. In pH-controlled batch fermentations with sugar mixtures, the

  18. Distinct molecular mechanisms involved in carbon catabolite repression of the arabinose regulon in Bacillus subtilis.

    PubMed

    Inácio, José Manuel; Costa, Carla; de Sá-Nogueira, Isabel

    2003-09-01

    The Bacillus subtilis proteins involved in the utilization of L-arabinose are encoded by the araABDLMNPQ-abfA metabolic operon and by the araE/araR divergent unit. Transcription from the ara operon, araE transport gene and araR regulatory gene is induced by L-arabinose and negatively controlled by AraR. Additionally, expression of both the ara operon and the araE gene is regulated at the transcriptional level by glucose repression. Here, by transcriptional fusion analysis in different mutant backgrounds, it is shown that CcpA most probably complexed with HPr-Ser46-P plays the major role in carbon catabolite repression of the ara regulon by glucose and glycerol. Site-directed mutagenesis and deletion analysis indicate that two catabolite responsive elements (cres) present in the ara operon (cre araA and cre araB) and one cre in the araE gene (cre araE) are implicated in this mechanism. Furthermore, cre araA located between the promoter region of the ara operon and the araA gene, and cre araB placed 2 kb downstream within the araB gene are independently functional and both contribute to glucose repression. In Northern blot analysis, in the presence of glucose, a CcpA-dependent transcript consistent with a message stopping at cre araB was detected, suggesting that transcription 'roadblocking' of RNA polymerase elongation is the most likely mechanism operating in this system. Glucose exerts an additional repression of the ara regulon, which requires a functional araR.

  19. Protein depletion using the arabinose promoter in Xanthomonas citri subsp. citri.

    PubMed

    Lacerda, Lilian A; Cavalca, Lucia B; Martins, Paula M M; Govone, José S; Bacci, Maurício; Ferreira, Henrique

    2017-03-23

    Xanthomonas citri subsp. citri (X. citri) is a plant pathogen and the etiological agent of citrus canker, a severe disease that affects all the commercially important citrus varieties, and has worldwide distribution. Citrus canker cannot be healed, and the best method known to control the spread of X. citri in the orchards is the eradication of symptomatic and asymptomatic plants in the field. However, in the state of São Paulo, Brazil, the main orange producing area in the world, control is evolving to an integrated management system (IMS) in which growers have to use less susceptible plants, windshields to prevent bacterial spread out and sprays of cupric bactericidal formulations. Our group has recently proposed alternative methods to control citrus canker, which are based on the use of chemical compounds able to disrupt vital cellular processes of X. citri. An important step in this approach is the genetic and biochemical characterization of genes/proteins that are the possible targets to be perturbed, a task not always simple when the gene/protein under investigation is essential for the organism. Here, we describe vectors carrying the arabinose promoter that enable controllable protein expression in X. citri. These vectors were used as complementation tools for the clean deletion of parB in X. citri, a widespread and conserved gene involved in the essential process of bacterial chromosome segregation. Overexpression or depletion of ParB led to increased cell size, which is probably a resultant of delayed chromosome segregation with subsequent retard of cell division. However, ParB is not essential in X. citri, and in its absence the bacterium was fully competent to colonize the host citrus and cause disease. The arabinose expression vectors described here are valuable tools for protein expression, and especially, to assist in the deletion of essential genes in X. citri.

  20. Genetic engineering and improvement of a Zymomonas mobilis for arabinose utilization and its performance on pretreated corn stover hydrolyzate

    SciTech Connect

    Chou, Yat -Chen; Linger, Jeffrey; Yang, Shihui; Zhang, Min

    2015-04-28

    In this paper, a glucose, xylose and arabinose utilizing Zymomonas mobilis strain was constructed by incorporating arabinose catabolic pathway genes, araBAD encoding L-ribulokinase, L-arabinose isomerase and L-ribulose-5-phosphate- 4-epimerase in a glucose, xylose co-fermenting host, 8b, using a transposition integration approach. Further improvement on this arabinose-capable integrant, 33C was achieved by applying a second transposition to create a genomic knockout (KO) mutant library. Using arabinose as a sole carbon source and a selection pressure, the KO library was subjected to a growth-enrichment process involving continuous sub-culturing for over 120 generations. Strain 13-1-17, isolated from such process demonstrated significant improvement in metabolizing arabinose in a dilute acid pretreated, saccharified corn stover slurry. Through Next Generation Sequencing (NGS) analysis, integration sites of the transposons were identified. Furthermore, multiple additional point mutations (SNPs: Single Nucleotide Polymorphisms) were discovered in 13-1-17, affecting genes araB and RpiB in the genome. Finally, we speculate that these mutations may have impacted the expression of the enzymes coded by these genes, ribulokinase and Ribose 5-P-isomerase, thus attributing to the improvement of the arabinose utilization.

  1. Toxicity and residual action of the photoactivated compound, cyano-alpha-terthienyl, and its efficacy for reducing pre-imaginal populations of mosquitoes.

    PubMed

    Dosdall, L M; Galloway, M M; Arnason, J T

    1992-06-01

    The photoactivated compound, cyano-alpha-terthienyl (cyano-alpha-T), was highly toxic to pre-imagines of the mosquitoes Culex restuans, Cx. tarsalis and Culiseta inornata when synergized with piperonyl butoxide (PBO). Lethal concentrations for 50% mortality, determined during an outdoor trial using caged fourth-instar Culex spp. larvae, were 19.4, 15.4 and 12.9 g/ha at 24, 48 and 72 h after treatment, respectively. No residual activity of cyano-alpha-T was observed beyond 24 h following treatment. In artificial pool tests, greatest population reductions were achieved using dosages of 20 and 40 g/ha; statistically significant reductions were not observed following applications of 5 g/ha. Cyano-alpha-T plus PBO was more effective for reducing mosquito populations than alpha-terthienyl (alpha-T) plus PBO at comparable dosages, although it exhibited slightly lower insecticidal activity at a dosage of 20 g/ha than a formulation of Bacillus thuringiensis var. israelensis (Vectobac 12 AS, 0.12 ml/m2). Greatest effectiveness of cyano-alpha-T plus PBO was observed in pools with low organic content relative to pools high in organic content.

  2. Effect of C-Terminal Protein Tags on Pentitol and l-Arabinose Transport by Ambrosiozyma monospora Lat1 and Lat2 Transporters in Saccharomyces cerevisiae

    PubMed Central

    Richard, Peter; Valkonen, Mari; Viljanen, Kaarina

    2014-01-01

    Functional expression in heterologous hosts is often less successful for integral membrane proteins than for soluble proteins. Here, two Ambrosiozyma monospora transporters were successfully expressed in Saccharomyces cerevisiae as tagged proteins. Growth of A. monospora on l-arabinose instead of glucose caused transport activities of l-arabinose, l-arabitol, and ribitol, measured using l-[1-3H]arabinose, l-[14C]arabitol, and [14C]ribitol of demonstrated purity. A. monospora LAT1 and LAT2 genes were cloned earlier by using their ability to improve the growth of genetically engineered Saccharomyces cerevisiae on l-arabinose. However, the l-arabinose and pentitol transport activities of S. cerevisiae carrying LAT1 or LAT2 are only slightly greater than those of control strains. S. cerevisiae carrying the LAT1 or LAT2 gene fused in frame to the genes for green fluorescent protein (GFP) or red fluorescent protein (mCherry) or adenylate kinase (AK) exhibited large (>3-fold for LAT1; >20-fold for LAT2) increases in transport activities. Lat1-mCherry transported l-arabinose with high affinity (Km ≈ 0.03 mM) and l-arabitol and ribitol with very low affinity (Km ≥ 75 mM). The Lat2-GFP, Lat2-mCherry, and Lat2-AK fusion proteins could not transport l-arabinose but were high-affinity pentitol transporters (Kms ≈ 0.2 mM). The l-arabinose and pentitol transport activities of A. monospora could not be completely explained by any combination of the observed properties of tagged Lat1 and Lat2, suggesting either that tagging and expression in a foreign membrane alters the transport kinetics of Lat1 and/or Lat2 or that A. monospora contains at least one more l-arabinose transporter. PMID:24561586

  3. Effect of C-terminal protein tags on pentitol and L-arabinose transport by Ambrosiozyma monospora Lat1 and Lat2 transporters in Saccharomyces cerevisiae.

    PubMed

    Londesborough, John; Richard, Peter; Valkonen, Mari; Viljanen, Kaarina

    2014-05-01

    Functional expression in heterologous hosts is often less successful for integral membrane proteins than for soluble proteins. Here, two Ambrosiozyma monospora transporters were successfully expressed in Saccharomyces cerevisiae as tagged proteins. Growth of A. monospora on l-arabinose instead of glucose caused transport activities of l-arabinose, l-arabitol, and ribitol, measured using l-[1-(3)H]arabinose, l-[(14)C]arabitol, and [(14)C]ribitol of demonstrated purity. A. monospora LAT1 and LAT2 genes were cloned earlier by using their ability to improve the growth of genetically engineered Saccharomyces cerevisiae on l-arabinose. However, the l-arabinose and pentitol transport activities of S. cerevisiae carrying LAT1 or LAT2 are only slightly greater than those of control strains. S. cerevisiae carrying the LAT1 or LAT2 gene fused in frame to the genes for green fluorescent protein (GFP) or red fluorescent protein (mCherry) or adenylate kinase (AK) exhibited large (>3-fold for LAT1; >20-fold for LAT2) increases in transport activities. Lat1-mCherry transported l-arabinose with high affinity (Km ≈ 0.03 mM) and l-arabitol and ribitol with very low affinity (Km ≥ 75 mM). The Lat2-GFP, Lat2-mCherry, and Lat2-AK fusion proteins could not transport l-arabinose but were high-affinity pentitol transporters (Kms ≈ 0.2 mM). The l-arabinose and pentitol transport activities of A. monospora could not be completely explained by any combination of the observed properties of tagged Lat1 and Lat2, suggesting either that tagging and expression in a foreign membrane alters the transport kinetics of Lat1 and/or Lat2 or that A. monospora contains at least one more l-arabinose transporter.

  4. Antihyperlipidemic and hepatoprotective activities of residue polysaccharide from Cordyceps militaris SU-12.

    PubMed

    Wang, Liqin; Xu, Nuo; Zhang, Jianjun; Zhao, Huajie; Lin, Lin; Jia, Shouhua; Jia, Le

    2015-10-20

    Cordyceps militaris has been artificially cultivated in China, and the great amounts of produced medium residue were discarded after the harvest. The aims of this work were to analyze the structure of the residue polysaccharide (RPS) of C. militaris SU-12, and to investigate the pharmacological effects of RPS on lipid metabolism and oxidative stress. RPS was composed of glucose, arabinose and mannose with a ratio of 62:1.6:1 by gas chromatography analysis, and the Mw (weight-average molecular weight), Mn (number-average molecular weight) and Mz (z-average molecular weight) of RPS were 2.86×10(3), 6.85×10(2), and 1.97×10(4)Da, respectively. The mice experiments demonstrated that RPS could reduce the levels of blood and liver lipid, and improve the glutamate pyruvate transaminase and antioxidant activity. The histopathological observations of mice livers indicated that RPS could attenuate liver cell injury. Results suggest that the RPS might be used as a potential antihyperlipidemic, hepatoprotective and antioxidant product.

  5. Chemical synthesis of Burkholderia Lipid A modified with glycosyl phosphodiester-linked 4-amino-4-deoxy-β-L-arabinose and its immunomodulatory potential.

    PubMed

    Hollaus, Ralph; Ittig, Simon; Hofinger, Andreas; Haegman, Mira; Beyaert, Rudi; Kosma, Paul; Zamyatina, Alla

    2015-03-02

    Modification of the Lipid A phosphates by positively charged appendages is a part of the survival strategy of numerous opportunistic Gram-negative bacteria. The phosphate groups of the cystic fibrosis adapted Burkholderia Lipid A are abundantly esterified by 4-amino-4-deoxy-β-L-arabinose (β-L-Ara4N), which imposes resistance to antibiotic treatment and contributes to bacterial virulence. To establish structural features accounting for the unique pro-inflammatory activity of Burkholderia LPS we have synthesised Lipid A substituted by β-L-Ara4N at the anomeric phosphate and its Ara4N-free counterpart. The double glycosyl phosphodiester was assembled by triazolyl-tris-(pyrrolidinyl)phosphonium-assisted coupling of the β-L-Ara4N H-phosphonate to α-lactol of β(1→6) diglucosamine, pentaacylated with (R)-(3)-acyloxyacyl- and Alloc-protected (R)-(3)-hydroxyacyl residues. The intermediate 1,1'-glycosyl-H-phosphonate diester was oxidised in anhydrous conditions to provide, after total deprotection, β-L-Ara4N-substituted Burkholderia Lipid A. The β-L-Ara4N modification significantly enhanced the pro-inflammatory innate immune signaling of otherwise non-endotoxic Burkholderia Lipid A.

  6. AraC protein, regulation of the l-arabinose operon in Escherichia coli, and the light switch mechanism of AraC action.

    PubMed

    Schleif, Robert

    2010-09-01

    This review covers the physiological aspects of regulation of the arabinose operon in Escherichia coli and the physical and regulatory properties of the operon's controlling gene, araC. It also describes the light switch mechanism as an explanation for many of the protein's properties. Although many thousands of homologs of AraC exist and regulate many diverse operons in response to many different inducers or physiological states, homologs that regulate arabinose-catabolizing genes in response to arabinose were identified. The sequence similarities among them are discussed in light of the known structure of the dimerization and DNA-binding domains of AraC.

  7. Ph+ ALL patients in first complete remission have similar survival after reduced intensity and myeloablative allogeneic transplantation: impact of tyrosine kinase inhibitor and minimal residual disease.

    PubMed

    Bachanova, V; Marks, D I; Zhang, M-J; Wang, H; de Lima, M; Aljurf, M D; Arellano, M; Artz, A S; Bacher, U; Cahn, J-Y; Chen, Y-B; Copelan, E A; Drobyski, W R; Gale, R P; Greer, J P; Gupta, V; Hale, G A; Kebriaei, P; Lazarus, H M; Lewis, I D; Lewis, V A; Liesveld, J L; Litzow, M R; Loren, A W; Miller, A M; Norkin, M; Oran, B; Pidala, J; Rowe, J M; Savani, B N; Saber, W; Vij, R; Waller, E K; Wiernik, P H; Weisdorf, D J

    2014-03-01

    The efficacy of reduced intensity conditioning (RIC) allogeneic hematopoietic cell transplantation (HCT) for Philadelphia chromosome positive (Ph+) acute lymphoblastic leukemia (ALL) is uncertain. We analyzed 197 adults with Ph+ ALL in first complete remission; 67 patients receiving RIC were matched with 130 receiving myeloablative conditioning (MAC) for age, donor type and HCT year. Over 75% received pre-HCT tyrosine kinase inhibitors (TKIs), mostly imatinib; 39% (RIC) and 49% (MAC) were minimal residual disease (MRD)(neg) pre-HCT. At a median 4.5 years follow-up, 1-year transplant-related mortality (TRM) was lower in RIC (13%) than MAC (36%; P=0.001) while the 3-year relapse rate was 49% in RIC and 28% in MAC (P=0.058). Overall survival (OS) was similar (RIC 39% (95% confidence interval (CI) 27-52) vs 35% (95% CI 27-44); P=0.62). Patients MRD(pos) pre-HCT had higher risk of relapse with RIC vs MAC (hazard ratio (HR) 1.97; P=0.026). However, patients receiving pre-HCT TKI in combination with MRD negativity pre-RIC HCT had superior OS (55%) compared with a similar MRD population after MAC (33%; P=0.0042). In multivariate analysis, RIC lowered TRM (HR 0.6; P=0.057), but absence of pre-HCT TKI (HR 1.88; P=0.018), RIC (HR 1.891; P=0.054) and pre-HCT MRD(pos) (HR 1.6; P=0.070) increased relapse risk. RIC is a valid alternative strategy for Ph+ ALL patients ineligible for MAC and MRD(neg) status is preferred pre-HCT.

  8. Aerobic Growth of Escherichia coli Is Reduced, and ATP Synthesis Is Selectively Inhibited when Five C-terminal Residues Are Deleted from the ϵ Subunit of ATP Synthase.

    PubMed

    Shah, Naman B; Duncan, Thomas M

    2015-08-21

    F-type ATP synthases are rotary nanomotor enzymes involved in cellular energy metabolism in eukaryotes and eubacteria. The ATP synthase from Gram-positive and -negative model bacteria can be autoinhibited by the C-terminal domain of its ϵ subunit (ϵCTD), but the importance of ϵ inhibition in vivo is unclear. Functional rotation is thought to be blocked by insertion of the latter half of the ϵCTD into the central cavity of the catalytic complex (F1). In the inhibited state of the Escherichia coli enzyme, the final segment of ϵCTD is deeply buried but has few specific interactions with other subunits. This region of the ϵCTD is variable or absent in other bacteria that exhibit strong ϵ-inhibition in vitro. Here, genetically deleting the last five residues of the ϵCTD (ϵΔ5) caused a greater defect in respiratory growth than did the complete absence of the ϵCTD. Isolated membranes with ϵΔ5 generated proton-motive force by respiration as effectively as with wild-type ϵ but showed a nearly 3-fold decrease in ATP synthesis rate. In contrast, the ϵΔ5 truncation did not change the intrinsic rate of ATP hydrolysis with membranes. Further, the ϵΔ5 subunit retained high affinity for isolated F1 but reduced the maximal inhibition of F1-ATPase by ϵ from >90% to ∼20%. The results suggest that the ϵCTD has distinct regulatory interactions with F1 when rotary catalysis operates in opposite directions for the hydrolysis or synthesis of ATP.

  9. Identification of GutQ from Escherichia coli as a D-arabinose 5-phosphate isomerase.

    PubMed

    Meredith, Timothy C; Woodard, Ronald W

    2005-10-01

    The glucitol operon (gutAEBDMRQ) of Escherichia coli encodes a phosphoenolpyruvate:sugar phosphotransferase system that metabolizes the hexitol D-glucitol (sorbitol). The functions for all but the last gene, gutQ, have been previously assigned. The high sequence similarity between GutQ and KdsD, a D-arabinose 5-phosphate isomerase (API) from the 3-deoxy-D-manno-octulosonate (KDO)-lipopolysaccharide (LPS) biosynthetic pathway, suggested a putative activity, but its role within the context of the gut operon remained unclear. Accordingly, the enzyme was cloned, overexpressed, and characterized. Recombinant GutQ was shown to indeed be a second copy of API from the E. coli K-12 genome with biochemical properties similar to those of KdsD, catalyzing the reversible aldol-ketol isomerization between D-ribulose 5-phosphate (Ru5P) and D-arabinose 5-phosphate (A5P). Genomic disruptions of each API gene were constructed in E. coli K-12. TCM11[(deltakdsD)] was capable of sustaining essential LPS synthesis at wild-type levels, indicating that GutQ functions as an API inside the cell. The gut operon remained inducible in TCM7[(deltagutQ)], suggesting that GutQ is not directly involved in d-glucitol catabolism. The conditional mutant TCM15[(deltagutQdeltakdsD)] was dependent on exogenous A5P both for LPS synthesis/growth and for upregulation of the gut operon. The phenotype was suppressed by complementation in trans with a plasmid encoding a functional copy of GutQ or by increasing the amount of A5P in the medium. As there is no obvious obligatory role for GutQ in the metabolism of d-glucitol and there is no readily apparent link between D-glucitol metabolism and LPS biosynthesis, it is suggested that A5P is not only a building block for KDO biosynthesis but also may be a regulatory molecule involved in expression of the gut operon.

  10. L-Ribose production from L-arabinose by immobilized recombinant Escherichia coli co-expressing the L-arabinose isomerase and mannose-6-phosphate isomerase genes from Geobacillus thermodenitrificans.

    PubMed

    Kim, Kyoung-Rok; Seo, Eun-Sun; Oh, Deok-Kun

    2014-01-01

    L-Ribose is an important precursor for antiviral agents, and thus its high-level production is urgently demanded. For this aim, immobilized recombinant Escherichia coli cells expressing the L-arabinose isomerase and variant mannose-6-phosphate isomerase genes from Geobacillus thermodenitrificans were developed. The immobilized cells produced 99 g/l L-ribose from 300 g/l L-arabinose in 3 h at pH 7.5 and 60 °C in the presence of 1 mM Co(2+), with a conversion yield of 33 % (w/w) and a productivity of 33 g/l/h. The immobilized cells in the packed-bed bioreactor at a dilution rate of 0.2 h(-1) produced an average of 100 g/l L-ribose with a conversion yield of 33 % and a productivity of 5.0 g/l/h for the first 12 days, and the operational half-life in the bioreactor was 28 days. Our study is first verification for L-ribose production by long-term operation and feasible for cost-effective commercialization. The immobilized cells in the present study also showed the highest conversion yield among processes from L-arabinose as the substrate.

  11. Direct production of D-arabinose from D-xylose by a coupling reaction using D-xylose isomerase, D-tagatose 3-epimerase and D-arabinose isomerase.

    PubMed

    Sultana, Ishrat; Mizanur, Rahman Md; Takeshita, Kei; Takada, Goro; Izumori, Ken

    2003-01-01

    Klebsiella pneumoniae 40bXX, a mutant strain that constitutively produces D-arabinose isomerase (D-AI), was isolated through a series of repeated subcultures from the parent strain on a mineral salt medium supplemented with L-Xylose as the sole carbon source. D-AI could be efficiently immobilized on chitopearl beads. The optimum temperature for the activity of the immobilized enzyme was 40 degrees C and the enzyme was stable up to 50 degrees C. The D-Al was active at pH 10.0 and was stable in the range of pH 6.0-11.0. The enzyme required manganese ions for maximum activity. Three immobilized enzymes, D-xylose isomerase (D-XI), D-tagatose 3-epimerase (D-TE and D-AI were used for the preparation of D-arabinose from D-xylose in a coupling reaction. After completion of the reaction, degradation of D-xylulose was carried out by Saccharomyces cerevisiae. The reaction mixture containing D-Xylose, D-ribulose and the product was then separated by ion exchange column chromatography. After crystallization, the product was checked by HPLC, IR spectroscopy, NMR spectroscopy and optical rotation measurements. Finally, 2.0 g of D-arabinose could be obtained from 5 g of the substrate.

  12. Estimation of D-Arabinose by Gas Chromatography/Mass Spectrometry as Surrogate for Mycobacterial Lipoarabinomannan in Human Urine

    PubMed Central

    De, Prithwiraj; Amin, Anita G.; Valli, Eloise; Perkins, Mark D.; McNeil, Michael; Chatterjee, Delphi

    2015-01-01

    Globally, tuberculosis is slowly declining each year and it is estimated that 37 million lives were saved between 2000 and 2013 through effective diagnosis and treatment. Currently, diagnosis relies on demonstration of the bacteria, Mycobacterium tuberculosis (Mtb), in clinical specimens by serial sputum microscopy, culture and molecular testing. Commercial immunoassay lateral flow kits developed to detect Mtb lipoglycan lipoarabinomannan (LAM) in urine as a marker of active TB exhibit poor sensitivity, especially in immunocompetent individuals, perhaps due to low abundance of the analyte. Our present study was designed to develop methods to validate the presence of LAM in a quantitative fashion in human urine samples obtained from culture-confirmed TB patients. Herein we describe, a consolidated approach for isolating LAM from the urine and quantifying D-arabinose as a proxy for LAM, using Gas Chromatography/Mass Spectrometry. 298 urine samples obtained from a repository were rigorously analyzed and shown to contain varying amounts of LAM-equivalent ranging between ~10–40 ng/mL. To further substantiate that D-arabinose detected in the samples originated from LAM, tuberculostearic acid, the unique 10-methyloctadecanoic acid present at the phosphatidylinositol end of LAM was also analyzed in a set of samples and found to be present confirming that the D-arabinose was indeed derived from LAM. Among the 144 samples from culture-negative TB suspects, 30 showed presence of D-arabinose suggesting another source of the analyte, such as disseminated TB or from non-tuberculosis mycobacterium. Our work validates that LAM is present in the urine samples of culture-positive patients in small but readily detectable amounts. The study further substantiates LAM in urine as a powerful biomarker for active tuberculosis. PMID:26633829

  13. Deoxyribonucleic acid-ribonucleic acid hybridization studies on the L-Arabinose operon of Escherichia coli B-r.

    PubMed

    Wilcox, G; Singer, J; Heffernan, L

    1971-10-01

    An increase in the rate of synthesis of ara-specific messenger ribonucleic acid as measured by deoxyribonucleic acid-ribonucleic acid hybridization has been detected in the induced wild-type (ara(+)) strain of Escherichia coli B/r as compared with the uninduced control, thus providing evidence that regulation of the positively controlled l-arabinose operon is at the level of transcription.

  14. Estimation of D-Arabinose by Gas Chromatography/Mass Spectrometry as Surrogate for Mycobacterial Lipoarabinomannan in Human Urine.

    PubMed

    De, Prithwiraj; Amin, Anita G; Valli, Eloise; Perkins, Mark D; McNeil, Michael; Chatterjee, Delphi

    2015-01-01

    Globally, tuberculosis is slowly declining each year and it is estimated that 37 million lives were saved between 2000 and 2013 through effective diagnosis and treatment. Currently, diagnosis relies on demonstration of the bacteria, Mycobacterium tuberculosis (Mtb), in clinical specimens by serial sputum microscopy, culture and molecular testing. Commercial immunoassay lateral flow kits developed to detect Mtb lipoglycan lipoarabinomannan (LAM) in urine as a marker of active TB exhibit poor sensitivity, especially in immunocompetent individuals, perhaps due to low abundance of the analyte. Our present study was designed to develop methods to validate the presence of LAM in a quantitative fashion in human urine samples obtained from culture-confirmed TB patients. Herein we describe, a consolidated approach for isolating LAM from the urine and quantifying D-arabinose as a proxy for LAM, using Gas Chromatography/Mass Spectrometry. 298 urine samples obtained from a repository were rigorously analyzed and shown to contain varying amounts of LAM-equivalent ranging between ~10-40 ng/mL. To further substantiate that D-arabinose detected in the samples originated from LAM, tuberculostearic acid, the unique 10-methyloctadecanoic acid present at the phosphatidylinositol end of LAM was also analyzed in a set of samples and found to be present confirming that the D-arabinose was indeed derived from LAM. Among the 144 samples from culture-negative TB suspects, 30 showed presence of D-arabinose suggesting another source of the analyte, such as disseminated TB or from non-tuberculosis mycobacterium. Our work validates that LAM is present in the urine samples of culture-positive patients in small but readily detectable amounts. The study further substantiates LAM in urine as a powerful biomarker for active tuberculosis.

  15. Development and application of an arabinose-inducible expression system by facilitating inducer uptake in Corynebacterium glutamicum.

    PubMed

    Zhang, Yun; Shang, Xiuling; Lai, Shujuan; Zhang, Guoqiang; Liang, Yong; Wen, Tingyi

    2012-08-01

    Corynebacterium glutamicum is currently used for the industrial production of a variety of biological materials. Many available inducible expression systems in this species use lac-derived promoters from Escherichia coli that exhibit much lower levels of inducible expression and leaky basal expression. We developed an arabinose-inducible expression system that contains the L-arabinose regulator AraC, the P(BAD) promoter from the araBAD operon, and the L-arabinose transporter AraE, all of which are derived from E. coli. The level of inducible P(BAD)-based expression could be modulated over a wide concentration range from 0.001 to 0.4% L-arabinose. This system tightly controlled the expression of the uracil phosphoribosyltransferase without leaky expression. When the gene encoding green fluorescent protein (GFP) was under the control of P(BAD) promoter, flow cytometry analysis showed that GFP was expressed in a highly homogeneous profile throughout the cell population. In contrast to the case in E. coli, P(BAD) induction was not significantly affected in the presence of different carbon sources in C. glutamicum, which makes it useful in fermentation applications. We used this system to regulate the expression of the odhI gene from C. glutamicum, which encodes an inhibitor of α-oxoglutarate dehydrogenase, resulting in high levels of glutamate production (up to 13.7 mM) under biotin nonlimiting conditions. This system provides an efficient tool available for molecular biology and metabolic engineering of C. glutamicum.

  16. Polarity in gene araB of the l-Arabinose operon in Escherichia coli B/r.

    PubMed

    Sheppard, D E; Walker, D A

    1969-11-01

    A series of mutations are described which map in the araB gene of the l-arabinose operon and exert a polar effect on gene araA, the structural gene for the l-arabinose isomerase. Ten of the 20 araB point mutants examined exhibited absolute polarity and may represent insertions of genetic material into the araB gene. The remaining 10 point mutants exhibit strong polarity (less than 10% of the normal wild-type inducible level of isomerase) and may represent a class of externally suppressible polar mutations other than amber or ochre. Seven of the 12 araB deletion mutants examined, or 58%, exhibit polarity, suggesting that a shift in the reading frame has been generated in the polycistronic message for the l-arabinose operon. The remaining, presumably in-phase, deletion mutants exhibit hyperinducible levels of isomerase, an effect that is eliminated when an araB(+) gene is introduced in the trans position. The hyperinducibility effect is discussed in terms of a model for self-catabolite repression, originally proposed by Katz and Englesberg.

  17. A unique arabinose 5-phosphate isomerase found within a genomic island associated with the uropathogenicity of Escherichia coli CFT073.

    PubMed

    Mosberg, Joshua A; Yep, Alejandra; Meredith, Timothy C; Smith, Sara; Wang, Pan-Fen; Holler, Tod P; Mobley, Harry L T; Woodard, Ronald W

    2011-06-01

    Previous studies showed that deletion of genes c3405 to c3410 from PAI-metV, a genomic island from Escherichia coli CFT073, results in a strain that fails to compete with wild-type CFT073 after a transurethral cochallenge in mice and is deficient in the ability to independently colonize the mouse kidney. Our analysis of c3405 to c3410 suggests that these genes constitute an operon with a role in the internalization and utilization of an unknown carbohydrate. This operon is not found in E. coli K-12 but is present in a small number of pathogenic E. coli and Shigella boydii strains. One of the genes, c3406, encodes a protein with significant homology to the sugar isomerase domain of arabinose 5-phosphate isomerases but lacking the tandem cystathionine beta-synthase domains found in the other arabinose 5-phosphate isomerases of E. coli. We prepared recombinant c3406 protein, found it to possess arabinose 5-phosphate isomerase activity, and characterized this activity in detail. We also constructed a c3406 deletion mutant of E. coli CFT073 and demonstrated that this deletion mutant was still able to compete with wild-type CFT073 in a transurethral cochallenge in mice and could colonize the mouse kidney. These results demonstrate that the presence of c3406 is not essential for a pathogenic phenotype.

  18. Metabolite gene regulation of the L-arabinose operon in Escherichia coli with indoleacetic acid and other indole derivatives.

    PubMed

    Kline, E L; Brown, C S; Bankaitis, V; Montefiori, D C; Craig, K

    1980-04-01

    The ability of indole derivatives to facilitate RNA polymerase transcription of the L-arabinose operon in Escherichia coli was shown to require the catabolite activator protein (CAP) as well as the araC gene product. Adenosine 3',5'-monophosphate (cAMP) was not obligatory for araBAD transcription when the cells were grown in the presence of 1 mM indole-3-acetic acid or in the presence of indole-3-acetamide, indole-3-propionic acid, indole-3-butyric acid, or 5-hydroxyindole-3-acetic acid. However, these indole derivatives were unable to circumvent the cAMP requirement for the induction of the lactose and the maltose operons. Catabolic repression occurred when glucose was added to cells grown in the presence of L-arabinose and 1 mM indoleacetic acid or 1 mM cAMP. This effect was reversed at higher concentrations of indoleacetic acid or cAMP. The induction and the catabolite repression phenomena were quantitated by measuring the differential rate of synthesis of L-arabinose isomerase (the araA gene product). These results indicated that indole metabolites from various living systems may regulate gene expression and may be involved in "metabolite gene regulation."

  19. The Cell Wall Arabinose-Deficient Arabidopsis thaliana Mutant murus5 Encodes a Defective Allele of REVERSIBLY GLYCOSYLATED POLYPEPTIDE2.

    PubMed

    Dugard, Christopher K; Mertz, Rachel A; Rayon, Catherine; Mercadante, Davide; Hart, Christopher; Benatti, Matheus R; Olek, Anna T; SanMiguel, Phillip J; Cooper, Bruce R; Reiter, Wolf-Dieter; McCann, Maureen C; Carpita, Nicholas C

    2016-07-01

    Traditional marker-based mapping and next-generation sequencing was used to determine that the Arabidopsis (Arabidopsis thaliana) low cell wall arabinose mutant murus5 (mur5) encodes a defective allele of REVERSIBLY GLYCOSYLATED POLYPEPTIDE2 (RGP2). Marker analysis of 13 F2 confirmed mutant progeny from a recombinant mapping population gave a rough map position on the upper arm of chromosome 5, and deep sequencing of DNA from these 13 lines gave five candidate genes with G→A (C→T) transitions predicted to result in amino acid changes. Of these five, only insertional mutant alleles of RGP2, a gene that encodes a UDP-arabinose mutase that interconverts UDP-arabinopyranose and UDP-arabinofuranose, exhibited the low cell wall arabinose phenotype. The identities of mur5 and two SALK insertional alleles were confirmed by allelism tests and overexpression of wild-type RGP2 complementary DNA placed under the control of the 35S promoter in the three alleles. The mur5 mutation results in the conversion of cysteine-257 to tyrosine-257 within a conserved hydrophobic cluster predicted to be distal to the active site and essential for protein stability and possible heterodimerization with other isoforms of RGP.

  20. Crystal Structure of Escherichia coli L-Arabinose Isomerase (ECAI), The Putative Target of Biological Tagatose Production

    SciTech Connect

    Manjasetty,B.; Chance, M.

    2006-01-01

    Escherichia coli L-arabinose isomerase (ECAI; EC 5.3.1.4) catalyzes the isomerization of L-arabinose to L-ribulose in vivo. This enzyme is also of commercial interest as it catalyzes the conversion of D-galactose to D-tagatose in vitro. The crystal structure of ECAI was solved and refined at 2.6 Angstroms resolution. The subunit structure of ECAI is organized into three domains: an N-terminal, a central and a C-terminal domain. It forms a crystallographic trimeric architecture in the asymmetric unit. Packing within the crystal suggests the idea that ECAI can form a hexameric assembly. Previous electron microscopic and biochemical studies supports that ECAI is hexameric in solution. A comparison with other known structures reveals that ECAI adopts a protein fold most similar to E. coli fucose isomerase (ECFI) despite very low sequence identity 9.7%. The structural similarity between ECAI and ECFI with regard to number of domains, overall fold, biological assembly, and active site architecture strongly suggests that the enzymes have functional similarities. Further, the crystal structure of ECAI forms a basis for identifying molecular determinants responsible for isomerization of arabinose to ribulose in vivo and galactose to tagatose in vitro.

  1. Fermentation of D-xylose and L-arabinose to ethanol by Erwinia chrysanthemi

    SciTech Connect

    Tolan, J.S.; Finn, R.K.

    1987-09-01

    Erwinia spp. are gram-negative facultative anaerobes within the family Enterobacteriacae which possess several desirable traits for the conversion of pentose sugars to ethanol, such as the ability to ferment a broad range of carbohydrates and the ease with which they can be genetically modified. Twenty-eight strains of Erwinia carotovora and E. chrysanthemi were screened for the ability to ferment D-xylose to ethanol. E. chrysanthemi B374 was chosen for further study on the basis of its superior (4%) ethanol tolerance. They have characterized the fermentation of D-xylose and L-arabinose by the wild type and mutants which bear plasmids containing the pyruvate decarboxylase gene from Zymomonas mobilis. Expression of the gene markedly increased the yields of ethanol (from 0.7 up to 1.45 mol/mol of xylose) and decreased the yields of formate, acetate, and lactate. However, the cells with pyruvate decarboxylase grew only one-fourth as fast as the wild type and tolerated only 2% ethanol. Alcohol tolerance was stimulated by the addition of yeast extract to the growth medium. Xylose catabolism was characterized by a high saturation constant K/sub s/ (4.5 mM).

  2. Translocation and interactions of L-arabinose in OmpF porin: A molecular dynamics study

    SciTech Connect

    Malek, Kourosh

    2007-01-05

    The passage of a natural substrate, L-arabinose (L-ARA) through Escherichia coli porin embedded in an artificial bilayer, is studied by equilibrium molecular dynamics simulations. We investigate the early stage of translocation process of L-ARA from intra-cellular to extra-cellular side (Int-to-Ext) across the bilayer. The average trajectory path over all L-ARA molecules along with quantum-mechanical configuration-optimizations at PM3 level predict the existence of at least three trapping zones. The common feature within all these zones is that L-ARA remains perpendicular to the channel axis. It is remarkable how the orientation and translational-rotational motion of L-ARA molecule play a role in its transport through OmpF channel. These simulations are important for better understanding of permeation process in OmpF channel. They also provide an insight into the chiral recognition of translocation process in protein nanochannels from substrate and protein prospects and help interpret experiments on permeation process of small dipolar molecules across biological membranes.

  3. Arabinose-rich polymers as an evolutionary strategy to plasticize resurrection plant cell walls against desiccation.

    PubMed

    Moore, John P; Nguema-Ona, Eric E; Vicré-Gibouin, Mäite; Sørensen, Iben; Willats, William G T; Driouich, Azeddine; Farrant, Jill M

    2013-03-01

    A variety of Southern African resurrection plants were surveyed using high-throughput cell wall profiling tools. Species evaluated were the dicotyledons, Myrothamnus flabellifolia and Craterostigma plantagineum; the monocotyledons, Xerophyta viscosa, Xerophyta schlecterii, Xerophyta humilis and the resurrection grass Eragrostis nindensis, as well as a pteridophyte, the resurrection fern, Mohria caffrorum. Comparisons were made between hydrated and desiccated leaf and frond material, with respect to cell wall composition and polymer abundance, using monosaccharide composition analysis, FT-IR spectroscopy and comprehensive microarray polymer profiling in combination with multivariate data analysis. The data obtained suggest that three main functional strategies appear to have evolved to prepare plant cell walls for desiccation. Arabinan-rich pectin and arabinogalactan proteins are found in the resurrection fern M. caffrorum and the basal angiosperm M. flabellifolia where they appear to act as 'pectic plasticizers'. Dicotyledons with pectin-rich walls, such as C. plantagineum, seem to use inducible mechanisms which consist of up-regulating wall proteins and osmoprotectants. The hemicellulose-rich walls of the grass-like Xerophyta spp. and the resurrection grass E. nindensis were found to contain highly arabinosylated xylans and arabinogalactan proteins. These data support a general mechanism of 'plasticising' the cell walls of resurrection plants to desiccation and implicate arabinose-rich polymers (pectin-arabinans, arabinogalactan proteins and arabinoxylans) as the major contributors in ensuring flexibility is maintained and rehydration is facilitated in these plants.

  4. Establishment of L-arabinose fermentation in glucose/xylose co-fermenting recombinant Saccharomyces cerevisiae 424A(LNH-ST) by genetic engineering.

    PubMed

    Bera, Aloke Kumar; Sedlak, Miroslav; Khan, Aftab; Ho, Nancy W Y

    2010-08-01

    Cost-effective and efficient ethanol production from lignocellulosic materials requires the fermentation of all sugars recovered from such materials including glucose, xylose, mannose, galactose, and L-arabinose. Wild-type strains of Saccharomyces cerevisiae used in industrial ethanol production cannot ferment D-xylose and L-arabinose. Our genetically engineered recombinant S. cerevisiae yeast 424A(LNH-ST) has been made able to efficiently ferment xylose to ethanol, which was achieved by integrating multiple copies of three xylose-metabolizing genes. This study reports the efficient anaerobic fermentation of L-arabinose by the derivative of 424A(LNH-ST). The new strain was constructed by over-expression of two additional genes from fungi L-arabinose utilization pathways. The resulting new 424A(LNH-ST) strain exhibited production of ethanol from L-arabinose, and the yield was more than 40%. An efficient ethanol production, about 72.5% yield from five-sugar mixtures containing glucose, galactose, mannose, xylose, and arabinose was also achieved. This co-fermentation of five-sugar mixture is important and crucial for application in industrial economical ethanol production using lignocellulosic biomass as the feedstock.

  5. Structural characterization of (1→2)-β-xylose-(1→3)-α-arabinose-containing oligosaccharide products of extracted switchgrass (Panicum virgatum, L.) xylan after exhaustive enzymatic treatment with α-arabinofuranosidase and β-endo-xylanase.

    PubMed

    Bowman, Michael J; Dien, Bruce S; Vermillion, Karl E; Mertens, Jeffrey A

    2014-10-29

    Switchgrass (Panicum virgatum, L.) is a potential dedicated biomass crop for use in biocatalytic conversion systems to biofuels. Nearly 30% of switchgrass cell wall material is xylan. The complete depolymerization of xylan is desirable both as an additional carbon source for microbial fermentation and to reduce inhibitory effects xylooligomers may have on cellulolytic glycoside hydrolase enzymes. To identify structural features of switchgrass xylan that are not distinguishable by mass spectrometry alone, a α-arabinofuranosidase enzyme was used to remove the arabinose side chains from alkali-extracted switchgrass xylan from three cultivars with simultaneous hydrolysis by β-endo-xylanase to enrich for oligosaccharide products with extended branching. The two most abundant enzymatic digestion products were separated and characterized by LC-MS(n), linkage analysis, and NMR. These two oligosaccharides were present in all three switchgrass cultivars and found to contain (1→2)-β-xylose-(1→3)-α-arabinose side chains, a linkage not previously reported in switchgrass.

  6. The elaborate route for UDP-arabinose delivery into the Golgi of plants.

    PubMed

    Rautengarten, Carsten; Birdseye, Devon; Pattathil, Sivakumar; McFarlane, Heather E; Saez-Aguayo, Susana; Orellana, Ariel; Persson, Staffan; Hahn, Michael G; Scheller, Henrik V; Heazlewood, Joshua L; Ebert, Berit

    2017-04-03

    In plants, L-arabinose (Ara) is a key component of cell wall polymers, glycoproteins, as well as flavonoids, and signaling peptides. Whereas the majority of Ara found in plant glycans occurs as a furanose ring (Araf), the activated precursor has a pyranose ring configuration (UDP-Arap). The biosynthesis of UDP-Arap mainly occurs via the epimerization of UDP-xylose (UDP-Xyl) in the Golgi lumen. Given that the predominant Ara form found in plants is Araf, UDP-Arap must exit the Golgi to be interconverted into UDP-Araf by UDP-Ara mutases that are located outside on the cytosolic surface of the Golgi. Subsequently, UDP-Araf must be transported back into the lumen. This step is vital because glycosyltransferases, the enzymes mediating the glycosylation reactions, are located within the Golgi lumen, and UDP-Arap, synthesized within the Golgi, is not their preferred substrate. Thus, the transport of UDP-Araf into the Golgi is a prerequisite. Although this step is critical for cell wall biosynthesis and the glycosylation of proteins and signaling peptides, the identification of these transporters has remained elusive. In this study, we present data demonstrating the identification and characterization of a family of Golgi-localized UDP-Araf transporters in Arabidopsis The application of a proteoliposome-based transport assay revealed that four members of the nucleotide sugar transporter (NST) family can efficiently transport UDP-Araf in vitro. Subsequent analysis of mutant lines affected in the function of these NSTs confirmed their role as UDP-Araf transporters in vivo.

  7. Microflow liquid chromatography coupled to mass spectrometry--an approach to significantly increase sensitivity, decrease matrix effects, and reduce organic solvent usage in pesticide residue analysis.

    PubMed

    Uclés Moreno, Ana; Herrera López, Sonia; Reichert, Barbara; Lozano Fernández, Ana; Hernando Guil, María Dolores; Fernández-Alba, Amadeo Rodríguez

    2015-01-20

    This manuscript reports a new pesticide residue analysis method employing a microflow-liquid chromatography system coupled to a triple quadrupole mass spectrometer (microflow-LC-ESI-QqQ-MS). This uses an electrospray ionization source with a narrow tip emitter to generate smaller droplets. A validation study was undertaken to establish performance characteristics for this new approach on 90 pesticide residues, including their degradation products, in three commodities (tomato, pepper, and orange). The significant benefits of the microflow-LC-MS/MS-based method were a high sensitivity gain and a notable reduction in matrix effects delivered by a dilution of the sample (up to 30-fold); this is as a result of competition reduction between the matrix compounds and analytes for charge during ionization. Overall robustness and a capability to withstand long analytical runs using the microflow-LC-MS system have been demonstrated (for 100 consecutive injections without any maintenance being required). Quality controls based on the results of internal standards added at the samples' extraction, dilution, and injection steps were also satisfactory. The LOQ values were mostly 5 μg kg(-1) for almost all pesticide residues. Other benefits were a substantial reduction in solvent usage and waste disposal as well as a decrease in the run-time. The method was successfully applied in the routine analysis of 50 fruit and vegetable samples labeled as organically produced.

  8. Novel transporters from Kluyveromyces marxianus and Pichia guilliermondii expressed in Saccharomyces cerevisiae enable growth on L-arabinose and D-xylose.

    PubMed

    Knoshaug, Eric P; Vidgren, Virve; Magalhães, Frederico; Jarvis, Eric E; Franden, Mary Ann; Zhang, Min; Singh, Arjun

    2015-10-01

    Genes encoding L-arabinose transporters in Kluyveromyces marxianus and Pichia guilliermondii were identified by functional complementation of Saccharomyces cerevisiae whose growth on L-arabinose was dependent on a functioning L-arabinose transporter, or by screening a differential display library, respectively. These transporters also transport D-xylose and were designated KmAXT1 (arabinose-xylose transporter) and PgAXT1, respectively. Transport assays using L-arabinose showed that KmAxt1p has K(m) 263 mM and V(max) 57 nM/mg/min, and PgAxt1p has K(m) 0.13 mM and V(max) 18 nM/mg/min. Glucose, galactose and xylose significantly inhibit L-arabinose transport by both transporters. Transport assays using D-xylose showed that KmAxt1p has K(m) 27 mM and V(max) 3.8 nM/mg/min, and PgAxt1p has K(m) 65 mM and V(max) 8.7 nM/mg/min. Neither transporter is capable of recovering growth on glucose or galactose in a S. cerevisiae strain deleted for hexose and galactose transporters. Transport kinetics of S. cerevisiae Gal2p showed K(m) 371 mM and V(max) 341 nM/mg/min for L-arabinose, and K(m) 25 mM and V(max) 76 nM/mg/min for galactose. Due to the ability of Gal2p and these two newly characterized transporters to transport both L-arabinose and D-xylose, one scenario for the complete usage of biomass-derived pentose sugars would require only the low-affinity, high-throughput transporter Gal2p and one additional high-affinity general pentose transporter, rather than dedicated D-xylose or L-arabinose transporters. Additionally, alignment of these transporters with other characterized pentose transporters provides potential targets for substrate recognition engineering.

  9. Characterization of strong polar mutations in a region immediately adjacent to the L-arabinose operator in Escherichia coli B-r.

    PubMed

    Eleuterio, M; Griffin, B; Sheppard, D E

    1972-08-01

    Seven l-arabinose-negative mutations are described that map in three genetically distinct regions immediately adjacent to the araO (operator) region of the l-arabinose operon. All seven mutants revert spontaneously, exhibit a cis-dominant, trans-recessive polarity effect upon the expression of l-arabinose isomerase (gene araA), and fail to respond to amber, ochre, or UGA suppressors. Three of these mutants exhibit absolute polarity and are not reverted by the mutangens 2-aminopurine, diethyl sulfate, and ICR-191. These may have arisen as a consequence of an insertion mutation in gene araB or in the initiator region of the l-arabinose operon. The four remaining mutants exhibit strong but not absolute polarity on gene araA and respond to the mutagens diethyl sulfate and ICR-191. Three of these mutants are suppressible by two independently isolated suppressors that fail to suppress known nonsense codons. Partially polar Ara(+) revertants with lesions linked to ara are obtained from three of the same four mutants. These polar mutants, their external suppressors, and their partially polar revertants are discussed in terms of the mechanism of initiation of expression of the l-arabinose operon.

  10. Production of the amino acids l-glutamate, l-lysine, l-ornithine and l-arginine from arabinose by recombinant Corynebacterium glutamicum.

    PubMed

    Schneider, Jens; Niermann, Karin; Wendisch, Volker F

    2011-07-10

    Amino acid production processes with Corynebacterium glutamicum are based on media containing glucose from starch hydrolysis or fructose and sucrose as present in molasses. Simultaneous utilization of various carbon sources, including glucose, fructose and sucrose, in blends is a typical characteristic of this bacterium. The renewable non-food carbon source arabinose, which is present in hemicellulosic hydrolysates, cannot be utilized by most C. glutamicum strains. Heterologous expression of the araBAD operon from Escherichia coli in the wild-type and in an l-lysine producing strain of C. glutamicum was shown to enable production of l-glutamate and l-lysine, respectively, from arabinose as sole carbon source. l-Ornithine and l-arginine producing strains were constructed and shown to produce l-ornithine and l-arginine from arabinose when araBAD from E. coli was expressed. Moreover, the recombinant strains produced l-glutamate, l-lysine, l-ornithine and l-arginine respectively, from arabinose also when glucose-arabinose blends were used as carbon sources.

  11. A simplified procedure for the preparation of 2,3-O-isopropylidene-sn-glycerol from L-arabinose.

    PubMed

    Kanda, P; Wells, M A

    1980-02-01

    A new procedure for the preparation of 2,3-O-isopropylidene-sn-glycerol is described. L-arabinose is converted to its 4,5-monoisopropylidene diethyl mercaptal derivative. This compound is then subjected to periodate oxidation and borohydride reduction. Following neutralization, the aceton-glycerol is extracted from the aqueous solution into chloroform. Evaporation of the chloroform and subsequent distillation yielded pure 2,3-O-isopropylidene-sn-glycerol ([alpha]D22 = -14.5 degrees (in substance)) in an overall yield of 15-25%.

  12. Role of minimal residual disease and chimerism after reduced-intensity and myeloablative allo-transplantation in acute myeloid leukemia and high-risk myelodysplastic syndrome.

    PubMed

    Bernal, Teresa; Diez-Campelo, María; Godoy, Vicky; Rojas, Silvia; Colado, Enrique; Alcoceba, Miguel; González, Marcos; Vidriales, Belén; Sánchez-Guijo, Fermín M; López-Corral, Lucía; Luño, Elisa; del Cañizo, Consuelo

    2014-05-01

    We evaluated the impact of detection of minimal residual disease by flow cytometry (FCMRD) and CD3 chimerism in relapse in a cohort of 87 patients with acute myeloid leukemia or myelodysplastic syndrome undergoing stem cell transplantation. Patients with a positive FCMRD at day +100 after transplantation showed higher relapse rates and worse overall survival. In multivariate analysis, a positive FCMRD after transplantation was a significant predictor of relapse. Mixed chimerism showed a trend to statistical signification. We conclude that FCMRD at day 100 after SCT is the best predictor of relapse after SCT in patients with aggressive myeloid malignancies.

  13. The presence of outer arm fucose residues on the N-glycans of tissue inhibitor of metalloproteinases-1 reduces its activity.

    PubMed

    Kim, Han Ie; Saldova, Radka; Park, Jun Hyoung; Lee, Young Hun; Harvey, David J; Wormald, Mark R; Wynne, Kieran; Elia, Giuliano; Kim, Hwa-Jung; Rudd, Pauline M; Lee, Seung-Taek

    2013-08-02

    Tissue inhibitor of metalloproteinases-1 (TIMP-1) inhibits matrix metalloproteinases (MMPs) by binding at a 1:1 stoichiometry. Here we have shown the involvement of N-glycosylation in the MMP inhibitory ability of TIMP-1. TIMP-1, purified from HEK 293 cells overexpressing TIMP-1 (293 TIMP-1), showed less binding and inhibitory abilities to MMPs than TIMP-1 purified from fibroblasts or SF9 insect cells infected with TIMP-1 baculovirus. Following deglycosylation of TIMP-1, all forms of TIMP-1 showed similar levels of MMP binding and inhibition, suggesting that glycosylation is involved in the regulation of these TIMP-1 activities. Analysis of the N-glycan structures showed that SF9 TIMP-1 has the simplest N-glycan structures, followed by fibroblast TIMP-1 and 293 TIMP-1, in order of increasing complexity in their N-glycan structures. Further analyses showed that cleavage of outer arm fucose residues from the N-glycans of 293 TIMP-1 or knockdown of both FUT4 and FUT7 (which encode for fucosyltransferases that add outer arm fucose residues to N-glycans) enhanced the MMP-binding and catalytic abilities of 293 TIMP-1, bringing them up to the levels of the other TIMP-1. These results demonstrate that the ability of TIMP-1 to inhibit MMPs is at least in part regulated by outer arm fucosylation of its N-glycans.

  14. Boost the electron mobility of solution-grown organic single crystals via reducing the amount of polar solvent residues

    SciTech Connect

    Xue, Guobiao; Xin, Huolin L.; Wu, Jiake; Fan, Congcheng; Liu, Shuang; Huang, Zhuoting; Liu, Yujing; Shan, Bowen; Miao, Qian; Chen, Hongzheng; Li, Hanying

    2015-10-29

    Enhancing electron transport to match with the development in hole transport is critical for organic electronics in the future. As electron motion is susceptible to extrinsic factors, seeking these factors and avoiding their negative effects have become the central challenge. Here, the existence of polar solvent residues in solution-grown single-crystals of 6,13-bis(triisopropylsilylethynyl)-5,7,12,14-tetraazapentacene is identified as a factor detrimental to electron motion. Field-effect transistors of the crystals exhibit electron mobility boosted by about 60% after the residues are removed. The average electron mobility reaches up to 8.0 ± 2.2 cm2 V–1 s–1 with a highest value of 13.3 cm2 V–1 s–1; these results are significantly higher than those obtained previously for the same molecule (1.0–5.0 cm2 V–1 s–1). Furthermore, the achieved mobility is also higher than the maximum reported electron mobility for organic materials (11 cm2 V–1 s–1). As a result, this work should greatly accelerate the advancement of organic electron-transporting materials.

  15. Arabinose substitution degree in xylan positively affects lignocellulose enzymatic digestibility after various NaOH/H2SO4 pretreatments in Miscanthus.

    PubMed

    Li, Fengcheng; Ren, Shuangfeng; Zhang, Wei; Xu, Zhengdan; Xie, Guosheng; Chen, Yan; Tu, Yuanyuan; Li, Qing; Zhou, Shiguang; Li, Yu; Tu, Fen; Liu, Lin; Wang, Yanting; Jiang, Jianxiong; Qin, Jingping; Li, Shizhong; Li, Qiwei; Jing, Hai-Chun; Zhou, Fasong; Gutterson, Neal; Peng, Liangcai

    2013-02-01

    Xylans are the major hemicelluloses in grasses, but their effects on biomass saccharification remain unclear. In this study, we examined the 79 representative Miscanthus accessions that displayed a diverse cell wall composition and varied biomass digestibility. Correlation analysis showed that hemicelluloses level has a strong positive effect on lignocellulose enzymatic digestion after NaOH or H(2)SO(4) pretreatment. Characterization of the monosaccharide compositions in the KOH-extractable and non-KOH-extractable hemicelluloses indicated that arabinose substitution degree of xylan is the key factor that positively affects biomass saccharification. The xylose/arabinose ratio after individual enzyme digestion revealed that the arabinose in xylan is partially associated with cellulose in the amorphous regions, which negatively affects cellulose crystallinity for high biomass digestibility. The results provide insights into the mechanism of lignocellulose enzymatic digestion upon pretreatment, and also suggest a goal for the genetic modification of hemicelluloses towards the bioenergy crop breeding of Miscanthus and grasses.

  16. Biosynthesis of UDP-xylose and UDP-arabinose in Sinorhizobium meliloti 1021: first characterization of a bacterial UDP-xylose synthase, and UDP-xylose 4-epimerase.

    PubMed

    Gu, Xiaogang; Lee, Sung G; Bar-Peled, Maor

    2011-01-01

    Sinorhizobium meliloti is a soil bacterium that fixes nitrogen after being established inside nodules that can form on the roots of several legumes, including Medicago truncatula. A mutation in an S. meliloti gene (lpsB) required for lipopolysaccharide synthesis has been reported to result in defective nodulation and an increase in the synthesis of a xylose-containing glycan. Glycans containing xylose as well as arabinose are also formed by other rhizobial species, but little is known about their structures and the biosynthetic pathways leading to their formation. To gain insight into the biosynthesis of these glycans and their biological roles, we report the identification of an operon in S. meliloti 1021 that contains two genes encoding activities not previously described in bacteria. One gene encodes a UDP-xylose synthase (Uxs) that converts UDP-glucuronic acid to UDP-xylose, and the second encodes a UDP-xylose 4-epimerase (Uxe) that interconverts UDP-xylose and UDP-arabinose. Similar genes were also identified in other rhizobial species, including Rhizobium leguminosarum, suggesting that they have important roles in the life cycle of this agronomically important class of bacteria. Functional studies established that recombinant SmUxs1 is likely to be active as a dimer and is inhibited by NADH and UDP-arabinose. SmUxe is inhibited by UDP-galactose, even though this nucleotide sugar is not a substrate for the 4-epimerase. Unambiguous evidence for the conversions of UDP-glucuronic acid to UDP-α-D-xylose and then to UDP-β-L-arabinose (UDP-arabinopyranose) was obtained using real-time (1)H-NMR spectroscopy. Our results provide new information about the ability of rhizobia to form UDP-xylose and UDP-arabinose, which are then used for the synthesis of xylose- and arabinose-containing glycans.

  17. L-Arabinose (pyranose and furanose rings)-branched poly (vinylalcohol): enzymatic synthesis of the sugar esters followed by free radical polymerization.

    PubMed

    Rodrigues Borges, Maurício; Balaban, Rosangela de Carvalho

    2014-12-20

    Herein this study reports the successful synthesis of a new poly(vinyl alcohol) (PVA), containing L-arabinose (L-arabinopyranose and arabinofuranose isomers) branched in only two steps: (1) production of polymerizable monomers of L-arabinose isomers (pyranose and furanose forms) through enzymatic synthesis using alkaline protease from Bacillus subtilis as catalyst and two substrates: L-arabinose and Divinyl Adipate (DVA) in N,N-dimethylformamide (DMF); (2) radical polymerization of the monomers, using an initiator system consisting of potassium persulfate and hydrogen peroxide in water. The transesterification of DVA with L-arabinose was monitored via qualitative analysis by TLC, confirming the formation of the vinyl sugar ester. The acylation occurred on the two different cyclic conformations of the L-arabinose which coexist in equilibrium: (α/β) arabinofuranose and (α/β) arabinopyranose. The acylation positions and the chemical structure of the 5-O-vinyl adipoyl L-arabinofuranose and 4-O-vinyl adipolyl L-arabinopyranose formed were determined by 13C NMR. The surface activity of the L-arabinose esters mixture (monomers) was compared with a commercial product based on phenol formaldehyde polyoxyalkylene polyamine, largely used as surfactant in many industries. FTIR spectroscopy of the sugar ester monomers and the respective polymer were compared revealing the disappearance of the vinyl group in the polymer spectrum. The polymer number-average molar mass (Mn) and the weight-average molar mass (Mw) were determined by gel permeation chromatography (GPC) presenting the following results: 2.9 × 10(4) Da and 7.2 × 10(4) Da, respectively, and polydispersity (Mw/Mn) equal to 2.48.

  18. Crystallization and preliminary X-ray crystallographic analysis of l-arabinose isomerase from thermophilic Geobacillus kaustophilus

    PubMed Central

    Cao, Thinh-Phat; Choi, Jin Myung; Lee, Sang-Jae; Lee, Yong-Jik; Lee, Sung-Keun; Jun, Youngsoo; Lee, Dong-Woo; Lee, Sung Haeng

    2014-01-01

    l-Arabinose isomerase (AI), which catalyzes the isomerization of l-arabinose to l-ribulose, can also convert d-galactose to d-tagatose, a natural sugar replacer, which is of commercial interest in the food and healthcare industries. Intriguingly, mesophilic and thermophilic AIs showed different substrate preferences and metal requirements in catalysis and different thermostabilities. However, the catalytic mechanism of thermophilic AIs still remains unclear. Therefore, thermophilic Geobacillus kaustophilus AI (GKAI) was overexpressed, purified and crystallized, and a preliminary X-ray diffraction data set was obtained. Diffraction data were collected from a GKAI crystal to 2.70 Å resolution. The crystal belonged to the monoclinic space group C2, with unit-cell parameters a = 224.12, b = 152.95, c = 91.28 Å, β = 103.61°. The asymmetric unit contained six molecules, with a calculated Matthews coefficient of 2.25 Å3 Da−1 and a solvent content of 45.39%. The three-dimensional structure determination of GKAI is currently in progress by molecular replacement and model building. PMID:24419630

  19. Mutations in the L-arabinose operon of Escherichia coli B-r that result in hypersensitivity to catabolite repression.

    PubMed

    Gendron, R P; Sheppard, D E

    1974-02-01

    Two independent mutants resistant to l-arabinose inhibition only in the presence of d-glucose were isolated from an l-arabinose-sensitive strain containing the araD139 mutation. Preliminary mapping studies indicate that these mutations are closely linked to the araIOC region. Addition of d-glucose to growing cultures of these mutants results in a 95 to 98% repression of ara operon expression, as compared to a 50% repression of the parental control. Since cultures of both mutant and parental strains undergo a 50% repression of lac operon expression upon addition of glucose, the hypersensitivity to catabolite repression exhibited by these mutants is specific for the ara operon. Addition of cyclic adenosine monophosphate reverses the catabolite repression of the ara operon in both mutant and parent strains to 70 to 80% of the control. It is suggested that in these mutants the affinity of the ara operon initiator region for the cAMP-catabolite-activator protein complex may have been altered.

  20. Isolation of specialized transducing bacteriophage lambda carrying genes of the L-arabinose operon of Escherichia coli B/r.

    PubMed

    Boulter, J; Lee, N

    1975-09-01

    A heat-inducible lysis-defective phage lambda (lambdacI857S7) has been integrated at multiple sites within the L-arabinose region (araCOIBAD) of a strain of Escherichia coli K-12 deleted for the normal lambda attachment site (lambdaattdelta). The lambda phage has become integrated with opposite orientations at two different loci within the aratb gene and with the "normal" orientation (clockwise N-RA-J) at a single site in the araC gene. The burst size, spontaneous-curing frequencies, and number of prophage harbored by each of the ara secondary-site lysogens have been determined. From these secondary-site lysogens it has been possible to generate plaque-forming ara-transducing phage (lambdapara) and defective ara-transducing phage (lambdadara), as well as defective leucine-transducing particles (lambdadleu). The construction and characterization of these lambdaara-transducing phage and their derivatives which carry genetically defined portions of the L-arabinose region are presented.

  1. Mutagenicity study on pyrazole, seven pyrazole derivatives, and two nitroimidazoles with the L-arabinose resistance test of Salmonella typhimurium

    SciTech Connect

    Alejandre-Duran, E.; Ruiz-Rubio, M.; Claramunt, R.M.; Lopez, C.; Pueyo, C.

    1986-01-01

    The mutagenicity of pyrazole and seven pyrazole derivatives (4-nitropyrazole, 4-bromopyrazole, 1-methyl-4-nitropyrazole, 3,5-dimethyl-4-nitropyrazole, 1-methyl-4-bromopyrazole, 4,4'-dinitro-1, 1'-methylene-dipyrazole and 4,4'-dibromo-1,1'-methylene-dipyrazole) has been investigated with the L-arabinose forward mutation assay of Salmonella typhimurium. Two nitroimidazoles (1-methyl-5-nitroimidazole and metronidazole) were included as reference drugs. The mutagenicity of each chemical was determined by both preincubation and liquid tests, in the presence or absence of S9 microsomal fraction. The mutagenic responses was expressed as the absolute number of L-arabinose resistant mutants growing in selective plates, supplemented with traces of D-glucose. Strain BA13 with a wild-type lipopolysaccharide barrier was used as a comparison to the deep rough derivative BA9. No mutagenic effect was detected with pyrazole and two of its derivatives, 1-methyl-4-bromopyrazole and 4,4'-dibromo-1,1'-methylene-dipyrazole. The other five pyrazole derivatives were mutagenic to different degrees, although their mutagenic potencies were always considerably lower than those of the two nitroimidazoles. The results suggest that 4-nitropyrazoles, as well as 4,4'-dinitro-1, 1'-methylene-dipyrazoles, should be investigated further as alternatives to, or even substitutes for, the currently used nitroimidazoles.

  2. Analysis of organo-chlorine pesticides residue in raw coffee with a modified "quick easy cheap effective rugged and safe" extraction/clean up procedure for reducing the impact of caffeine on the gas chromatography-mass spectrometry measurement.

    PubMed

    Bresin, Bruno; Piol, Maria; Fabbro, Denis; Mancini, Maria Antonietta; Casetta, Bruno; Del Bianco, Clorinda

    2015-01-09

    The control of pesticide residues on raw coffee is a task of great importance due to high consumption of this beverage in Italy and in many other countries. High caffeine content can hamper extraction and measurement of any pesticide residue. A tandem extraction protocol has been devised by exploiting the quick easy cheap effective rugged and safe (QuEChERS) scheme for extraction, coupled to a dispersive liquid-liquid micro-extraction (DLLME) in order to drastically reduce caffeine content in the final extract. Gas chromatography-mass spectrometry (GC-MS) has been used for quantification of organo-chlorine pesticides in single ion monitoring (SIM) mode. Method has been validated and performances meet the criteria prescribed by European Union regulations.

  3. Use of Interface Treatment to Reduce Emissions from Residuals in Lower Permeability Zones to Groundwater flowing Through More Permeable Zones (Invited)

    NASA Astrophysics Data System (ADS)

    Johnson, P.; Cavanagh, B.; Clifton, L.; Daniels, E.; Dahlen, P.

    2013-12-01

    Many soil and groundwater remediation technologies rely on fluid flow for contaminant extraction or reactant delivery (e.g., soil vapor extraction, pump and treat, in situ chemical oxidation, air sparging, enhanced bioremediation). Given that most unconsolidated and consolidated settings have permeability contrasts, the outcome is often preferential treatment of more permeable zones and ineffective treatment of the lower permeability zones. When this happens, post-treatment contaminant emissions from low permeability zone residuals can cause unacceptable long-term impacts to groundwater in the transmissive zones. As complete remediation of the impacted lower permeability zones may not be practicable with conventional technologies, one might explore options that lead to reduction of the contaminant emissions to acceptable levels, rather than full remediation of the lower permeability layers. This could be accomplished either by creating a sustained emission reaction/attenuation zone at the high-low permeability interface, or by creating a clean soil zone extending sufficiently far into the lower permeability layer to cause the necessary reduction in contaminant concentration gradient and diffusive emission. These options are explored in proof-of-concept laboratory-scale physical model experiments. The physical models are prepared with two layers of contrasting permeability and either dissolved matrix storage or nonaqueous phase liquid (NAPL) in the lower permeability layer. A dissolved oxidant is then delivered to the interface via flow across the higher permeability layer and changes in contaminant emissions from the low permeability zone are monitored before, during, and after oxidant delivery. The use of three oxidants (dissolved oxygen, hydrogen peroxide and sodium persulfate) for treatment of emissions from petroleum hydrocarbon residuals is examined.

  4. Biochar from sugarcane filtercake reduces soil CO2 emissions relative to raw residue and improves water retention and nutrient availability in a highly-weathered tropical soil.

    PubMed

    Eykelbosh, Angela Joy; Johnson, Mark S; Santos de Queiroz, Edmar; Dalmagro, Higo José; Guimarães Couto, Eduardo

    2014-01-01

    In Brazil, the degradation of nutrient-poor Ferralsols limits productivity and drives agricultural expansion into pristine areas. However, returning agricultural residues to the soil in a stabilized form may offer opportunities for maintaining or improving soil quality, even under conditions that typically promote carbon loss. We examined the use of biochar made from filtercake (a byproduct of sugarcane processing) on the physicochemical properties of a cultivated tropical soil. Filtercake was pyrolyzed at 575°C for 3 h yielding a biochar with increased surface area and porosity compared to the raw filtercake. Filtercake biochar was primarily composed of aromatic carbon, with some residual cellulose and hemicellulose. In a three-week laboratory incubation, CO2 effluxes from a highly weathered Ferralsol soil amended with 5% biochar (dry weight, d.w.) were roughly four-fold higher than the soil-only control, but 23-fold lower than CO2 effluxes from soil amended with 5% (d.w.) raw filtercake. We also applied vinasse, a carbon-rich liquid waste from bioethanol production typically utilized as a fertilizer on sugarcane soils, to filtercake- and biochar-amended soils. Total CO2 efflux from the biochar-amended soil in response to vinasse application was only 5% of the efflux when vinasse was applied to soil amended with raw filtercake. Furthermore, mixtures of 5 or 10% biochar (d.w.) in this highly weathered tropical soil significantly increased water retention within the plant-available range and also improved nutrient availability. Accordingly, application of sugarcane filtercake as biochar, with or without vinasse application, may better satisfy soil management objectives than filtercake applied to soils in its raw form, and may help to build soil carbon stocks in sugarcane-cultivating regions.

  5. Biochar from Sugarcane Filtercake Reduces Soil CO2 Emissions Relative to Raw Residue and Improves Water Retention and Nutrient Availability in a Highly-Weathered Tropical Soil

    PubMed Central

    Eykelbosh, Angela Joy; Johnson, Mark S.; Santos de Queiroz, Edmar; Dalmagro, Higo José; Guimarães Couto, Eduardo

    2014-01-01

    In Brazil, the degradation of nutrient-poor Ferralsols limits productivity and drives agricultural expansion into pristine areas. However, returning agricultural residues to the soil in a stabilized form may offer opportunities for maintaining or improving soil quality, even under conditions that typically promote carbon loss. We examined the use of biochar made from filtercake (a byproduct of sugarcane processing) on the physicochemical properties of a cultivated tropical soil. Filtercake was pyrolyzed at 575°C for 3 h yielding a biochar with increased surface area and porosity compared to the raw filtercake. Filtercake biochar was primarily composed of aromatic carbon, with some residual cellulose and hemicellulose. In a three-week laboratory incubation, CO2 effluxes from a highly weathered Ferralsol soil amended with 5% biochar (dry weight, d.w.) were roughly four-fold higher than the soil-only control, but 23-fold lower than CO2 effluxes from soil amended with 5% (d.w.) raw filtercake. We also applied vinasse, a carbon-rich liquid waste from bioethanol production typically utilized as a fertilizer on sugarcane soils, to filtercake- and biochar-amended soils. Total CO2 efflux from the biochar-amended soil in response to vinasse application was only 5% of the efflux when vinasse was applied to soil amended with raw filtercake. Furthermore, mixtures of 5 or 10% biochar (d.w.) in this highly weathered tropical soil significantly increased water retention within the plant-available range and also improved nutrient availability. Accordingly, application of sugarcane filtercake as biochar, with or without vinasse application, may better satisfy soil management objectives than filtercake applied to soils in its raw form, and may help to build soil carbon stocks in sugarcane-cultivating regions. PMID:24897522

  6. Homo-D-lactic acid fermentation from arabinose by redirection of the phosphoketolase pathway to the pentose phosphate pathway in L-lactate dehydrogenase gene-deficient Lactobacillus plantarum.

    PubMed

    Okano, Kenji; Yoshida, Shogo; Tanaka, Tsutomu; Ogino, Chiaki; Fukuda, Hideki; Kondo, Akihiko

    2009-08-01

    Optically pure d-lactic acid fermentation from arabinose was achieved by using the Lactobacillus plantarum NCIMB 8826 strain whose l-lactate dehydrogenase gene was deficient and whose phosphoketolase gene was substituted with a heterologous transketolase gene. After 27 h of fermentation, 38.6 g/liter of d-lactic acid was produced from 50 g/liter of arabinose.

  7. Reduced Order Model Based Feedback Control of Large-Scale Aeroelastic Simulations: Residual State Filter Model Reduction Compensation and Application to F-16 Dynamic Models

    DTIC Science & Technology

    2008-01-23

    Journal of Mathematical Analysis and Applications , pp...Reduced-Order Feedback Control of Distributed parameter Systems via Singular Perturbation Methods. Balas, Mark J. 1982, Journal of Mathematical Analysis and Applications , pp...Perturbations. Balas, Mark J. 1984, Journal of Mathematical Analysis and Applications , pp. 80-104. - 47 -

  8. L-Arabinose binding, isomerization, and epimerization by D-xylose isomerase: X-ray/neutron crystallographic and molecular simulation study.

    PubMed

    Langan, Paul; Sangha, Amandeep K; Wymore, Troy; Parks, Jerry M; Yang, Zamin Koo; Hanson, B Leif; Fisher, Zoe; Mason, Sax A; Blakeley, Matthew P; Forsyth, V Trevor; Glusker, Jenny P; Carrell, Horace L; Smith, Jeremy C; Keen, David A; Graham, David E; Kovalevsky, Andrey

    2014-09-02

    D-xylose isomerase (XI) is capable of sugar isomerization and slow conversion of some monosaccharides into their C2-epimers. We present X-ray and neutron crystallographic studies to locate H and D atoms during the respective isomerization and epimerization of L-arabinose to L-ribulose and L-ribose, respectively. Neutron structures in complex with cyclic and linear L-arabinose have demonstrated that the mechanism of ring-opening is the same as for the reaction with D-xylose. Structural evidence and QM/MM calculations show that in the reactive Michaelis complex L-arabinose is distorted to the high-energy (5)S1 conformation; this may explain the apparent high KM for this sugar. MD-FEP simulations indicate that amino acid substitutions in a hydrophobic pocket near C5 of L-arabinose can enhance sugar binding. L-ribulose and L-ribose were found in furanose forms when bound to XI. We propose that these complexes containing Ni(2+) cofactors are Michaelis-like and the isomerization between these two sugars proceeds via a cis-ene-diol mechanism.

  9. Investigation of the interconversion of L­arabinose and D­xylose as regulated by candidate pathway genes in Beta vulgaris using comparative genomics

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Arabinose and xylose occur in hemicellulose, a group of polysaccharides present in plant cell walls in all terrestrial plants. Xylose is an aldopentose sugar with uses as a chemical feedstock, and this study sought to explore the possibility of using sugar beet as an industrial source of xylose, wh...

  10. delta-Aminolevulinate dehydratase inhibition by 2,3-dimercaptopropanol is mediated by chelation of zinc from a site involved in maintaining cysteinyl residues in a reduced state.

    PubMed

    Emanuelli, T; Rocha, J B; Pereira, M E; Nascimento, P C; Souza, D O; Beber, F A

    1998-09-01

    The mechanisms underlying mouse delta-aminolevulinate dehydratase (ALA-D) inhibition by a chelating agent used in the treatment of heavy metal poisoning, 2,3-dimercaptopropanol (British Anti-Lewisite), were investigated. ALA-D inhibition by 2,3-dimercaptopropanol was totally reversed by 25-100 microM Zn2+, indicating that inhibition was due to chelation of zinc by 2,3-dimercaptopropanol. Our data suggested that zinc bound to a labile site (displaced by 25-40 microM EDTA or 500 microM 2,3-dimercaptopropanol) is involved in maintaining the sulfhydryl groups of ALA-D in a reduced state (essential for enzyme activity), since inhibition by these compounds was reversed by 10 mM dithiotreitol (a reducing agent). On the other hand, 10 mM dithiotreitol did not reverse ALA-D inhibition by a higher concentration of EDTA (100 microM). Accordingly, 2,3-dimercaptopropanol appears to inhibit ALA-D through a mechanism similar to that of low EDTA concentrations. Neither oxidized 2,3-dimercaptopropanol nor reactive oxygen species appeared to contribute for ALA-D inhibition by reduced 2,3-dimercaptopropanol. Taken together, these results suggest that 2,3-dimercaptopropanol inhibits ALA-D by chelating Zn2+ from a labile site that is involved in maintaining enzyme sulfhydryl groups in a reduced state. This site is compatible with the ZnB or Zn beta previously described in mammalian and bacterial ALA-D.

  11. Mode of action of AraR, the key regulator of L-arabinose metabolism in Bacillus subtilis.

    PubMed

    Mota, L J; Tavares, P; Sá-Nogueira, I

    1999-08-01

    The AraR protein is a negative regulator involved in L-arabinose-inducible expression of the Bacillus subtilis araABDLMNPQ-abfA metabolic operon and of the araE/araR genes that are organized as a divergent transcriptional unit. The two ara gene clusters are found at different positions in the bacterial chromosome. AraR was overproduced in Escherichia coli and purified to more than 95% homogeneity. AraR binds specifically to DNA fragments carrying the promoter region of the ara genes. DNase I protection assays showed that AraR binds to two sequences within the promoters of the araABDLMNPQ-abfA operon and the araE gene, and to one sequence in the araR promoter. The AraR target sequences are palindromic and share high identity, defining a 16 bp AraR consensus operator sequence showing half-symmetry, ATTTGTAC. Binding of AraR to DNA was inhibited by L-arabinose but not by other sugars. The two operator sites within the araABDLMNPQ-abfA operon and araE promoters are located on the same side of the DNA helix, and a pattern of enhanced and diminished DNase I cleavage was observed between them, but not in the araR promoter. Quantitative DNase I footprinting in DNA templates containing one, two or three AraR binding sites showed that the repressor binds cooperatively to the two operator sites within the metabolic operon and araE promoters but not to the site located in the araR promoter. These results are consistent with two modes for AraR transcriptional repression that might correlate with different physiological requirements: a high level of repression is achieved by DNA bending requiring two in-phase operator sequences (metabolic operon and araE transport gene), whereas binding to a single operator, which autoregulates araR expression, is 10-fold less effective.

  12. Novel substrate specificity of D-arabinose isomerase from Klebsiella pneumoniae and its application to production of D-altrose from D-psicose.

    PubMed

    Menavuvu, Buetusiwa Thomas; Poonperm, Wayoon; Takeda, Kosei; Morimoto, Kenji; Granström, Tom Birger; Takada, Goro; Izumori, Ken

    2006-11-01

    d-Arabinose isomerase from Klebsiella pneumoniae 40bXX was purified 12-fold with a 62.5% yield indicated by its electrophoretic homogeneity. The purified enzyme showed the highest activities toward d-arabinose and l-fucose as substrates at optimum conditions (50 mM glycine-NaOH, pH 9.0, 40 degrees C). The enzyme had a broad range of substrate specificities toward various d/l-aldoses, i.e., d-arabinose, l-fucose, d/l-xylose, d-mannose, d/l-lyxose, l-glucose, d-altrose and d/l-galactose. The equilibrium ratios between d-arabinose and d-ribulose, l-fucose and l-fuculose, d-altrose and d-psicose, and l-galactose and l-tagatose were 90:10, 90:10, 13:87 and 25:75, respectively. Using a combination of the immobilized d-tagatose 3-epimerase and d-arabinose isomerase, we achieved the production of d-altrose from d-fructose in a batch reactor. We successfully produced approximately 12 g of d-altrose from 200 g of d-fructose in a reaction series with an overall yield of 6%. The product obtained was confirmed to be d-altrose by HPLC and (13)C-NMR. To the best of our knowledge, this is the first report on the production of d-altrose from a cheap sugar, d-fructose, using an enzymatic method.

  13. Optimization of acid hydrolysis from the hemicellulosic fraction of Eucalyptus grandis residue using response surface methodology.

    PubMed

    Canettieri, Eliana Vieira; de Moraes Rocha, George Jackson; de Carvalho, João Andrade; de Almeida e Silva, João Batista

    2007-01-01

    Biotechnological conversion of biomass into fuels and chemicals requires hydrolysis of the polysaccharide fraction into monomeric sugars. Hydrolysis can be performed enzymatically and with dilute or concentrate mineral acids. The present study used dilute sulfuric acid as a catalyst for hydrolysis of Eucalyptus grandis residue. The purpose of this paper was to optimize the hydrolysis process in a 1.4 l pilot-scale reactor and investigate the effects of the acid concentration, temperature and residue/acid solution ratio on the hemicellulose removal and consequently on the production of sugars (xylose, glucose and arabinose) as well as on the formation of by-products (furfural, 5-hydroxymethylfurfural and acetic acid). This study was based on a model composition corresponding to a 2(3) orthogonal factorial design and employed the response surface methodology (RSM) to optimize the hydrolysis conditions, aiming to attain maximum xylose extraction from hemicellulose of residue. The considered optimum conditions were: H(2)SO(4) concentration of 0.65%, temperature of 157 degrees C and residue/acid solution ratio of 1/8.6 with a reaction time of 20 min. Under these conditions, 79.6% of the total xylose was removed and the hydrolysate contained 1.65 g/l glucose, 13.65 g/l xylose, 1.55 g/l arabinose, 3.10 g/l acetic acid, 1.23 g/l furfural and 0.20 g/l 5-hydroxymethylfurfural.

  14. Assessment of agro-industrial and composted organic wastes for reducing the potential leaching of triazine herbicide residues through the soil.

    PubMed

    Fenoll, José; Vela, Nuria; Navarro, Ginés; Pérez-Lucas, Gabriel; Navarro, Simón

    2014-09-15

    In this study, we examined the effect of four different organic wastes--composted sheep manure (CSM), spent coffee grounds (SCG), composted pine bark (CPB) and coir (CR)--on the sorption, persistence and mobility of eight symmetrical and two asymmetrical-triazine herbicides: atrazine, propazine, simazine, terbuthylazine (chlorotriazines), prometon (methoxytriazine), prometryn, simetryn, terbutryn (methylthiotriazines), metamitron and metribuzin (triazinones). The downward movement of herbicides was monitored using disturbed soil columns packed with a clay loam soil (Hipercalcic calcisol) under laboratory conditions. For unamended and amended soils, the groundwater ubiquity score (GUS) was calculated for each herbicide on the basis of its persistence (as t½) and mobility (as KOC). All herbicides showed medium/high leachability through the unamended soils. The addition of agro-industrial and composted organic wastes at a rate of 10% (w:w) strongly decreased the mobility of herbicides. Sorption coefficients normalized to the total soil organic carbon (KOC) increased in the amended soils. These results suggest that used organic wastes could be used to enhance the retention and reduce the mobility of the studied herbicides in soil.

  15. The influence of Aspergillus niger transcription factors AraR and XlnR in the gene expression during growth in D-xylose, L-arabinose and steam-exploded sugarcane bagasse.

    PubMed

    de Souza, Wagner Rodrigo; Maitan-Alfenas, Gabriela Piccolo; de Gouvêa, Paula Fagundes; Brown, Neil Andrew; Savoldi, Marcela; Battaglia, Evy; Goldman, Maria Helena S; de Vries, Ronald P; Goldman, Gustavo Henrique

    2013-11-01

    The interest in the conversion of plant biomass to renewable fuels such as bioethanol has led to an increased investigation into the processes regulating biomass saccharification. The filamentous fungus Aspergillus niger is an important microorganism capable of producing a wide variety of plant biomass degrading enzymes. In A. niger the transcriptional activator XlnR and its close homolog, AraR, controls the main (hemi-)cellulolytic system responsible for plant polysaccharide degradation. Sugarcane is used worldwide as a feedstock for sugar and ethanol production, while the lignocellulosic residual bagasse can be used in different industrial applications, including ethanol production. The use of pentose sugars from hemicelluloses represents an opportunity to further increase production efficiencies. In the present study, we describe a global gene expression analysis of A. niger XlnR- and AraR-deficient mutant strains, grown on a D-xylose/L-arabinose monosaccharide mixture and steam-exploded sugarcane bagasse. Different gene sets of CAZy enzymes and sugar transporters were shown to be individually or dually regulated by XlnR and AraR, with XlnR appearing to be the major regulator on complex polysaccharides. Our study contributes to understanding of the complex regulatory mechanisms responsible for plant polysaccharide-degrading gene expression, and opens new possibilities for the engineering of fungi able to produce more efficient enzymatic cocktails to be used in biofuel production.

  16. Ph+ ALL patients in first complete remission have similar survival after reduced intensity and myeloablative allogeneic transplantation: Impact of tyrosine kinase inhibitor and minimal residual disease

    PubMed Central

    Bachanova, Veronika; Marks, David I.; Zhang, Mei-Jie; Wang, Hailin; de Lima, Marcos; Aljurf, Mahmoud D.; Arellano, Martha; Artz, Andrew S.; Bacher, Ulrike; Cahn, Jean-Yves; Chen, Yi-Bin; Copelan, Edward A.; Drobyski, William R.; Gale, Robert Peter; Greer, John P; Gupta, Vikas; Hale, Gregory A.; Kebriaei, Partow; Lazarus, Hillard M.; Lewis, Ian D.; Lewis, Victor A.; Liesveld, Jane L.; Litzow, Mark R.; Loren, Alison W.; Miller, Alan M.; Norkin, Maxim; Oran, Betul; Pidala, Joseph; Rowe, Jacob M.; Savani, Bipin N.; Saber, Wael; Vij, Ravi; Waller, Edmund K.; Wiernik, Peter H.; Weisdorf, Daniel J.

    2014-01-01

    The efficacy of reduced intensity conditioning (RIC) allogeneic hematopoietic cell transplantation (HCT) for Ph+ acute lymphoblastic leukemia (ALL) is uncertain. We analyzed 197 adults with Ph+ ALL in first complete remission; 67 patients receiving RIC were matched with 130 receiving myeloablative conditioning (MAC) for age, donor type, and HCT year. Over 75% received pre-HCT tyrosine kinase inhibitors (TKI), mostly imatinib; 39% (RIC) and 49% (MAC) were MRDneg pre-HCT. At a median 4.5 years follow-up, 1-year transplant-related mortality (TRM) was lower in RIC (13%) than MAC (36%;p=0.001) while the 3-year relapse rate was 49% in RIC and 28% in MAC (p=0.058). Overall survival was similar (RIC 39% [95% CI:27–52] vs. 35% [95% CI:270–44];p=0.62). Patients MRDpos pre-HCT had higher risk of relapse with RIC versus MAC (HR 1.97;p=0.026). However, patients receiving pre-HCT TKI in combination with MRD negativity pre-RIC HCT had superior OS (55%) compared to a similar MRDneg population after MAC (33%; p=0.0042). In multivariate analysis, RIC lowered TRM (HR 0.6; p=0.057), but absence of pre-HCT TKI (HR 1.88;p=0.018), RIC (HR 1.891;p=0.054) and pre-HCT MRDpos (HR 1.6; p=0.070) increased relapse risk. RIC is a valid alternative strategy for Ph+ ALL patients ineligible for MAC and MRDneg status is preferred pre-HCT. PMID:23989431

  17. Negative regulation of L-arabinose metabolism in Bacillus subtilis: characterization of the araR (araC) gene.

    PubMed

    Sá-Nogueira, I; Mota, L J

    1997-03-01

    The Bacillus subtilis araC locus, mapped at about 294 degrees on the genetic map, was defined by mutations conferring an Ara- phenotype to strains bearing the metabolic araA, araB, and araD wild-type alleles (located at about 256 degrees on the genetic map) and by mutants showing constitutive expression of the three genes. In previous work, it has been postulated that the gene in which these mutations lie exerts its effect on the ara metabolic operon in trans, and this locus was named araC by analogy to the Escherichia coli regulatory gene. Here, we report the cloning and sequencing of the araC locus. This region comprises two open reading frames with divergently arranged promoters, the regulatory gene, araC, encoding a 41-kDa polypeptide, and a partially cloned gene, termed araE, which most probably codes for a permease involved in the transport of L-arabinose. The DNA sequence of araC revealed that its putative product is very similar to a number of bacterial negative regulators (the GalR-LacI family). However, a helix-turn-helix motif was identified in the N-terminal region by its identity to the consensus signature sequence of another group of repressors, the GntR family. The lack of similarity between the predicted primary structure of the product encoded by the B. subtilis regulatory gene and the AraC regulator from E. coli and the apparently different modes of action of these two proteins lead us to propose a new name, araR, for this gene. The araR gene is monocistronic, and the promoter region contains -10 and -35 regions (as determined by primer extension analysis) similar to those recognized by RNA polymerase containing the major vegetative cell sigma factor sigmaA. An insertion-deletion mutation in the araR gene leads to constitutive expression of the L-arabinose metabolic operon. We demonstrate that the araR gene codes for a negative regulator of the ara operon and that the expression of araR is repressed by its own product.

  18. An in vitro transposon system for highly regulated gene expression: construction of Escherichia coli strains with arabinose-dependent growth at low temperatures.

    PubMed

    Grant, A J; Haigh, R; Williams, P; O'Connor, C D

    2001-12-12

    Placing a gene of interest under the control of an inducible promoter greatly aids the purification, localization and functional analysis of proteins but usually requires the sub-cloning of the gene of interest into an appropriate expression vector. Here, we describe an alternative approach employing in vitro transposition of Tn Omega P(BAD) to place the highly regulable, arabinose inducible P(BAD) promoter upstream of the gene to be expressed. The method is rapid, simple and facilitates the optimization of expression by producing constructs with variable distances between the P(BAD) promoter and the gene. To illustrate the use of this approach, we describe the construction of a strain of Escherichia coli in which growth at low temperatures on solid media is dependent on threshold levels of arabinose. Other uses of the transposable promoter are also discussed.

  19. A single and two step isomerization process for d-tagatose and l-ribose bioproduction using l-arabinose isomerase and d-lyxose isomerase.

    PubMed

    Patel, Manisha J; Akhani, Rekha C; Patel, Arti T; Dedania, Samir R; Patel, Darshan H

    2017-02-01

    l-ribose and d-tagatose are biochemically synthesized using sugar isomerases. The l-arabinose isomerase gene from Shigella flexneri (Sf-AI) was cloned and expressed in Escherichia coli BL-21. Sf-AI was applied for the bioproduction of d-tagatose from d-galactose. l-ribose synthesis was performed by two step isomerization using Sf-AI and d-lyxose/ribose isomerase from Cohnella laevoribosii. The overall 22.3% and 25% conversion rate were observed for d-tagatose and l-ribose production from d-galactose and l-arabinose respectively. In the present manuscript, synthesis of rare sugars from naturally available sugars is discussed along with the biochemical characterization of Sf-AI and its efficiency.

  20. Subcritical carbon dioxide-water hydrolysis of sugarcane bagasse pith for reducing sugars production.

    PubMed

    Liang, Jiezhen; Chen, Xiaopeng; Wang, Linlin; Wei, Xiaojie; Wang, Huasheng; Lu, Songzhou; Li, Yunhua

    2017-03-01

    The aim of present study was to obtain total reducing sugars (TRS) by hydrolysis in subcritical CO2-water from sugarcane bagasse pith (SCBP), the fibrous residue remaining after papermaking from sugarcane bagasse. The optimum hydrolysis conditions were evaluated by L16(4(5)) orthogonal experiments. The TRS yield achieved 45.8% at the optimal conditions: 200°C, 40min, 500rmin(-1), CO2 initial pressure of 1MPa and liquid-to-solid ratio of 50:1. Fourier transform infrared spectrometry and two-dimensional heteronuclear single quantum coherence nuclear magnetic resonance were used to characterize hydrolysis liquor, treated and untreated SCBP, resulting in the removal of hemicelluloses to mainly produce xylose, glucose and arabinose during hydrolysis. The severity factors had no correlation to TRS yield, indicating that the simple kinetic processes of biomass solubilisation cannot perfectly describe the SCBP hydrolysis. The first-order kinetic model based on consecutive reaction was used to obtain rate constants, activation energies and pre-exponential factors.

  1. Targeted deletion of the ara operon of Salmonella typhimurium enhances L-arabinose accumulation and drives PBAD-promoted expression of anti-cancer toxins and imaging agents.

    PubMed

    Hong, Hyun; Lim, Daejin; Kim, Geun-Joong; Park, Seung-Hwan; Sik Kim, Hyeon; Hong, Yeongjin; Choy, Hyon E; Min, Jung-Joon

    2014-01-01

    Tumor-specific expression of antitumor drugs can be achieved using attenuated Salmonella typhimurium harboring the PBAD promoter, which is induced by L-arabinose. However, L-arabinose does not accumulate because it is metabolized to D-xylulose-5-P by enzymes encoded by the ara operon in Salmonellae. To address this problem, we developed an engineered strain of S. typhimurium in which the ara operon is deleted. Linear DNA transformation was performed using λ red recombinase to exchange the ara operon with linear DNA carrying an antibiotic-resistance gene with homology to regions adjacent to the ara operon. The ara operon-deleted strain and its parental strain were transformed with a plasmid encoding Renilla luciferase variant 8 (RLuc8) or cytolysin A (clyA) under the control of the PBAD promoter. Luciferase assays demonstrated that RLuc8 expression was 49-fold higher in the ara operon-deleted S. typhimurium than in the parental strain after the addition of L-arabinose. In vivo bioluminescence imaging showed that the tumor tissue targeted by the ara operon-deleted Salmonella had a stronger imaging signal (~30-fold) than that targeted by the parental strain. Mice with murine colon cancer (CT26) that had been injected with the ara operon-deleted S. typhimurium expressing clyA showed significant tumor suppression. The present report demonstrates that deletion of the ara operon of S. typhimurium enhances L-arabinose accumulation and thereby drives PBAD-promoted expression of cytotoxic agents and imaging agents. This is a promising approach for tumor therapy and imaging.

  2. The Escherichia coli L-arabinose operon: binding sites of the regulatory proteins and a mechanism of positive and negative regulation.

    PubMed

    Ogden, S; Haggerty, D; Stoner, C M; Kolodrubetz, D; Schleif, R

    1980-06-01

    The locations of DNA binding by the proteins involved with positive and negative regulation of transcription initiation of the L-arabinose operon in Escherichia coli have been determined by the DNase I protection method. Two cyclic AMP receptor protein sites were found, at positions -78 to -107 and -121 to -146, an araC protein--arabinose binding site was found at position -40 to -78, and an araC protein-fucose binding site was found at position -106 to -144. These locations, combined with in vivo data on induction of the two divergently oriented arabinose promoters, suggest the following regulatory mechanism: induction of the araBAD operon occurs when cyclic AMP receptor protein, araC protein, and RNA polymerase are all present and able to bind to DNA. Negative regulation is accomplished by the repressing form of araC protein binding to a site in the regulatory region such that it stimultaneously blocks access of cyclic AMP receptor protein to two sites on the DNA, one site of which serves each of the two promoters. Thus, from a single operator site, the negative regulator represses the two outwardly oriented ara promoters. This regulatory mechanism explains the known positive and negative regulatory properties of the ara promoters.

  3. XacR - a novel transcriptional regulator of D-xylose and L-arabinose catabolism in the haloarchaeon Haloferax volcanii.

    PubMed

    Johnsen, Ulrike; Sutter, Jan-Moritz; Schulz, Anne-Christine; Tästensen, Julia-Beate; Schönheit, Peter

    2015-05-01

    The haloarchaeon Haloferax volcanii degrades D-xylose and L-arabinose via oxidative pathways to α-ketoglutarate. The genes involved in these pathways are clustered and were transcriptionally upregulated by both D-xylose and L-arabinose suggesting a common regulator. Adjacent to the gene cluster, a putative IclR-like transcriptional regulator, HVO_B0040, was identified. It is shown that HVO_B0040, designated xacR, encodes an activator of both D-xylose and L-arabinose catabolism: in ΔxacR cells, transcripts of genes involved in pentose catabolism could not be detected; transcript formation could be recovered by complementation, indicating XacR dependent transcriptional activation. Upstream activation promoter regions and nucleotide sequences that were essential for XacR-mediated activation of pentose-specific genes were identified by in vivo deletion and scanning mutagenesis. Besides its activator function XacR acted as repressor of its own synthesis: xacR deletion resulted in an increase of xacR promoter activity. A palindromic sequence was identified at the operator site of xacR promoter, and mutation of this sequence also resulted in an increase and thus derepression of xacR promoter activity. It is concluded that the palindromic sequence represents the binding site of XacR as repressor. This is the first report of a transcriptional regulator of pentose catabolism in the domain of archaea.

  4. Synergistic production of L-arabinose from arabinan by the combined use of thermostable endo- and exo-arabinanases from Caldicellulosiruptor saccharolyticus.

    PubMed

    Lim, Yu-Ri; Yeom, Soo-Jin; Kim, Young-Su; Oh, Deok-Kun

    2011-03-01

    The optimum conditions for the production of L-arabinose from debranched arabinan were determined to be pH 6.5, 75°C, 20 g l(-1) debranched arabinan, 42 Um l(-1) endo-1,5-α-L-arabinanase, and 14 U ml(-1) α-L-arabinofuranosidase from Caldicellulosiruptor saccharolyticus and the conditions for sugar beet arabinan were pH 6.0, 75°C, 20 g l(-1) sugar beet arabinan, 3 U ml(-1) endo-1,5-α-L-arabinanase, and 24 U ml(-1) α-L-arabinofuranosidase. Under the optimum conditions, 16 g l(-1)l-arabinose was obtained from 20 g l(-1) debranched arabinan or sugar beet arabinan after 120 min, with a hydrolysis yield of 80% and a productivity of 8 g l(-1)h(-1). This is the first reported trial for the production of L-arabinose from the hemicellulose arabinan by the combined use of endo- and exo-arabinanases.

  5. Crystal Structure of Mn2+-bound Escherichia coli L-arabinose Isomerase (ECAI) and Implications in Protein Catalytic Mechanism and Thermo-Stability

    SciTech Connect

    Zhu,W.; Manjasetty, B.; Chance, M.

    2007-01-01

    The functional properties of proteins depend on their three-dimensional shapes. Protein structures can be determined by X-ray crystallography as a tool. The three-dimensional structure of the apo form of the Escherichia coli L-arabinose isomerase (ECAI) has recently been determined. ECAI is responsible for the initial stage of L-arabinose catabolism, converting arabinose into ribulose in vivo. This enzyme also plays a crucial role in catalyzing the conversion of galactose into tagatose (low calorie natural sugar) in vitro. ECAI utilizes Mn{sup 2+} for its catalytic activity. Crystals of the ECAI + Mn{sup 2+} complex helps to investigate the catalytic properties of the enzyme. Therefore, crystals of ECAI + Mn{sup 2+} complex were grown using hanging drop vapor diffusion method at room temperature. Diffraction data were collected at X4C beamline, National Synchrotron Light Source, Brookhaven National Laboratory. The structure was solved by the molecular replacement technique and has been refined to Rwork of 0.23 at 2.8 {angstrom} resolution using X3A beamline computational facility. The structure was deposited to Protein Data Bank (PDB ID 2HXG). Mn{sup 2+} ion was localized to the previously identified putative active site with octahedral coordination. Comparison of apo and holo form of ECAI structures permits the identification of structural features that are of importance to the intrinsic activity and heat stability of AI.

  6. The Cell Wall Arabinose-Deficient Arabidopsis thaliana Mutant murus5 Encodes a Defective Allele of REVERSIBLY GLYCOSYLATED POLYPEPTIDE21[OPEN

    PubMed Central

    Dugard, Christopher K.; Olek, Anna T.; Cooper, Bruce R.

    2016-01-01

    Traditional marker-based mapping and next-generation sequencing was used to determine that the Arabidopsis (Arabidopsis thaliana) low cell wall arabinose mutant murus5 (mur5) encodes a defective allele of REVERSIBLY GLYCOSYLATED POLYPEPTIDE2 (RGP2). Marker analysis of 13 F2 confirmed mutant progeny from a recombinant mapping population gave a rough map position on the upper arm of chromosome 5, and deep sequencing of DNA from these 13 lines gave five candidate genes with G→A (C→T) transitions predicted to result in amino acid changes. Of these five, only insertional mutant alleles of RGP2, a gene that encodes a UDP-arabinose mutase that interconverts UDP-arabinopyranose and UDP-arabinofuranose, exhibited the low cell wall arabinose phenotype. The identities of mur5 and two SALK insertional alleles were confirmed by allelism tests and overexpression of wild-type RGP2 complementary DNA placed under the control of the 35S promoter in the three alleles. The mur5 mutation results in the conversion of cysteine-257 to tyrosine-257 within a conserved hydrophobic cluster predicted to be distal to the active site and essential for protein stability and possible heterodimerization with other isoforms of RGP. PMID:27217494

  7. Regulatory properties of araC(c) mutants in the L-arabinose operon of escherichia coliB/r.

    PubMed

    MacInnes, K R; Sheppard, D E; Falgout, B

    1978-01-01

    Merodiploids containing a high-constitutive and a low-constitutive araC(c) allele were assayed for constitutive expression of the ara operon. Low-constitutive araC(c) alleles either were unable to repress the constitutive rate of ara operon expression exhibited by by high-constitutive araC(c) alleles or achieved a partial repression of the high-constitutive rate of operon expression. Either mutation to a low-constitutive araC(c) mutant resulted in a partial or complete loss of repressor function, or subunit mixing between the two araC(c) mutant proteins resulted in a partial or complete dominance of the high-constitutive araC(c) allele. Five of the six araC(c) alleles tested allowed a partial induction of the ara operon in cya crp background. In general, a higher level of ara operon induction was achieved in the cya crp background by high araC(c) alleles than by low araC(c) alleles. Furthermore, several araC(c) mutants exhibited decreased sensitivity to catabolite repression, particularly in the presence of inducer. The results suggest a model in which certain araC(c) gene products can achieve ara operon induction in the presence of either arabinose (inducer) or catabolite activator protein-cyclic adenosine monophosphate, whereas the wild-type araC gene product requires the presence of both of these factors for operon expression.

  8. Regulation of the L-arabinose operon in strains of Escherichia coli containing ColE1-ara hybrid plasmids.

    PubMed

    Wallace, L J; Wilcox, G

    1979-06-20

    Hybrid plasmids were constructed from fragments of F'ara episomes formed by the restriction endonuclease EcoRI and a linear form of the plasmid ColE1 created by cleavage with EcoRI. Hybrid plasmids were constructed containing the entire ara region or the ara region with various parts deleted. E. coli K12 host strains were constructed which contained different deletions of the ara region. The hybrid plasmids were transferred to those strains whose ara deletion complemented that of the plasmid. The initial differential rates of synthesis of L-arabinose isomerase, the product of the araA gene, were determined for the Ara+, plasmid containing strains. These studies demonstrated that strains containing delta(araOIBA)718 produce elevated levels of araC protein, suggesting the araC promoter has been altered by this deletion. Evidence is also presented which suggests that araC protein activates the ara-BAD operon to higher levels when it is present in cis rather than trans. Amplification of the products of the cloned genes is observed when compared to haploid levels in some cases.

  9. Interaction between mutant alleles of araC of the Escherichia coli B/r L-arabinose operon.

    PubMed

    Sheppard, D E; Eleuterio, M; Falgout, B

    1979-09-01

    Strains were constructed that contain mutational alterations affecting two distinct functional domains within the araC gene protein. The araCi (catabolite repression insensitivity) and araCh (catabolite repression hypersensitivity) mutations were used to alter the catabolite repression sensitivity domain, and mutation to D-fucose resistance was used to alter the inducer binding domain. araCh, D-fucose-resistant double mutants never exhibited constitutive ara operon expression, whereas all of the araCi, D-fucose-resistant double mutants did exhibit constitutivity. When L-arabinose was used as an inducer, most of the double mutants exhibited the sensitivity to catabolite repression associated with the araCi or araCh mutation. However, when D-fucose was used as an inducer, changes in sensitivity to catabolite repression were observed that were attributed to interactions between the two protein domains. The roles of catabolite activator protein and araC gene protein in the induction of the araBAD operon were discussed.

  10. Identification and characterization of a novel L-arabinose isomerase from Anoxybacillus flavithermus useful in D-tagatose production.

    PubMed

    Li, Yanjun; Zhu, Yueming; Liu, Anjun; Sun, Yuanxia

    2011-05-01

    D-Tagatose is a highly functional rare ketohexose and many attempts have been made to convert D-galactose into the valuable D-tagatose using L-arabinose isomerase (L-AI). In this study, a thermophilic strain possessing L-AI gene was isolated from hot spring sludge and identified as Anoxybacillus flavithermus based on its physio-biochemical characterization and phylogenetic analysis of its 16s rRNA gene. Furthermore, the gene encoding L-AI from A. flavithermus (AFAI) was cloned and expressed at a high level in E. coli BL21(DE3). L-AI had a molecular weight of 55,876 Da, an optimum pH of 10.5 and temperature of 95°C. The results showed that the conversion equilibrium shifted to more D-tagatose from D-galactose by raising the reaction temperatures and adding borate. A 60% conversion of D-galactose to D-tagatose was observed at an isomerization temperature of 95°C with borate. The catalytic efficiency (k (cat) /K (m)) for D-galactose with borate was 9.47 mM(-1) min(-1), twice as much as that without borate. Our results indicate that AFAI is a novel hyperthermophilic and alkaliphilic isomerase with a higher catalytic efficiency for D-galactose, suggesting its great potential for producing D-tagatose.

  11. Growth inhibitory effect of D-arabinose against the nematode Caenorhabditis elegans: Discovery of a novel bioactive monosaccharide.

    PubMed

    Sakoguchi, Hirofumi; Yoshihara, Akihide; Shintani, Tomoya; Okuma, Kazuhiro; Izumori, Ken; Sato, Masashi

    2016-02-01

    Biological activities of unusual monosaccharides (rare sugars) have largely remained unstudied until recently. We compared the growth inhibitory effects of aldohexose stereoisomers against the animal model Caenorhabditis elegans cultured in monoxenic conditions with Escherichia coli as food. Among these stereoisomers, the rare sugar D-arabinose (D-Ara) showed particularly strong growth inhibition. The IC50 value for D-Ara was estimated to be 7.5 mM, which surpassed that of the potent glycolytic inhibitor 2-deoxy-D-glucose (19.5 mM) used as a positive control. The inhibitory effect of D-Ara was also observed in animals cultured in axenic conditions using a chemically defined medium; this excluded the possible influence of E. coli. To our knowledge, this is the first report of biological activity of D-Ara. The D-Ara-induced inhibition was recovered by adding either D-ribose or D-fructose, but not D-glucose. These findings suggest that the inhibition could be induced by multiple mechanisms, for example, disturbance of D-ribose and D-fructose metabolism.

  12. Phenolic components of the primary cell wall. Feruloylated disaccharides of D-galactose and L-arabinose from spinach polysaccharide.

    PubMed

    Fry, S C

    1982-05-01

    1. Cell walls from rapidly growing cell suspension cultures of Spinacia oleracea L. contained ferulic acid and p-coumaric acid esterified with a water-insoluble polymer. 2. Prolonged treatment with trypsin did not release may feruloyl esters from dearabinofuranosylated cell walls, and the polymer was also insoluble in phenol/acetic acid/water (2:1:1, w/v/v). 3. Treatment of the cell walls with the fungal hydrolase preparation "Driselase' did liberate low-Mr feruloyl esters. The major esters were 4-O-(6-O-feruloyl-beta-D-galactopyranosyl)-D-galactose and 3?-O-feruloyl-alpha-L-arabinopyranosyl)-L-arabinose. These two esters accounted for about 60% of the cell-wall ferulate. 4. It is concluded that the feruloylation of cell-wall polymers is not a random process, but occurs at very specific sites, probably on the arabinogalactan component of pectin. 5. The possible role of such phenolic substituents in cell-wall architecture and growth is discussed.

  13. Feruloyl-L-arabinose attenuates migration, invasion and production of reactive oxygen species in H1299 lung cancer cells.

    PubMed

    Fang, Hsin-Yu; Wang, Hui-Min; Chang, Kuo-Feng; Hu, Huei-Ting; Hwang, Lian-Je; Fu, Tzu-Fun; Lin, Yin-Chieh; Chang, Wei-Chiao; Chiu, Tsu-Pei; Wen, Zhi-Hong; Fong, Yao; Chiu, Chien-Chih; Chen, Bing-Hung

    2013-08-01

    Ferulic acid (FA), a phenolic compound, is an abundant dietary antioxidant and exerts the mitogenic effect on cells. Recently, we isolated an active FA derivative, namely feruloyl-L-arabinose (FAA), from coba husk. The aim of this study was to investigate the effects of FAA on the proliferation, migration and invasion of H1299 human lung cancer cells. Our results showed a strong antioxidant potential of FAA. Additionally, FAA inhibited the migration and invasion ability, while causing a significant accumulation of G2/M-population, of H1299 tumor cells in a dose-dependent manner, whereas no significant change on cell proliferation was observed. Results from the wound healing assay revealed that cell migration ability was markedly inhibited by FAA treatments. Similarly, results of gelatin zymography study showed that FAA treatments significantly decreased the activities of matrix metalloproteinase (MMP)-2 and MMP-9, suggesting that FAA-mediated inhibition on migration and invasion of lung cancer cells may be achieved by the down-regulation of the MMPs activities. Taken together, our present work provides a new insight into the novel inhibitory function of FAA on cell migration in H1299 cells, suggesting its promising role in the chemoprevention of lung cancer.

  14. RESIDUAL RISK ASSESSMENTS - RESIDUAL RISK ...

    EPA Pesticide Factsheets

    This source category previously subjected to a technology-based standard will be examined to determine if health or ecological risks are significant enough to warrant further regulation for Coke Ovens. These assesments utilize existing models and data bases to examine the multi-media and multi-pollutant impacts of air toxics emissions on human health and the environment. Details on the assessment process and methodologies can be found in EPA's Residual Risk Report to Congress issued in March of 1999 (see web site). To assess the health risks imposed by air toxics emissions from Coke Ovens to determine if control technology standards previously established are adequately protecting public health.

  15. Theoretical Study on the Factors Controlling the Stability of the Borate Complexes of Ribose, Arabinose, Lyxose and Xylose

    SciTech Connect

    Sumpter, Bobby G; Fuentes-Cabrera, Miguel A; Leszczynski, Jerzy; Sponer, Judit; Sponer, Jiri

    2008-01-01

    Recent views on the origin of the "RNA world" suggest that complexation with borate minerals had an indispensable role at stabilizing the cyclic form of aldopentoses that are the potential building blocks of RNA. Experimental investigations by Li Q, Ricardo A, Benner SA, Winefordner JD, Powell DH (2005) Anal Chem 77:4503-4508 and Chapelle S, Verchere J-F (1988) Tetrahedron 44:4469-4482 have shown that stability of the 2:1 complexes formed between ribose and borate is superior to those of the analogous compounds of the other three aldopentoses (xylose, arabinose and lyxose). The distinct stability of the ribose-borate 2:1 complexes is thought to be one of the basic reasons why evolution selected ribose (out of the four aldopentoses) to build up RNA molecules. Here we disclose the factors governing the stability of the aldopentose-borate 2:1 complexes using Density Functional Theory electronic structure calculations with inclusion of solvation effects using a continuum solvent approach. Our results show that the strong electrostatic field of the borate anion leads to the reorientation of the hydroxyl groups of the aldopentoses relative to the geometry adopted in the non-complexed form. The reasons why complex formation between borate and ribose is clearly preferred over the other three aldopentoses is (i) the ribose 3-OH is involved in a H-bond with one of the borate-oxygens and (ii) its 5-CH2OH group is well separated in space from the negatively charged region of the complex and ensures favorable contact with the aqueous medium.

  16. Control of the arabinose regulon in Bacillus subtilis by AraR in vivo: crucial roles of operators, cooperativity, and DNA looping.

    PubMed

    Mota, L J; Sarmento, L M; de Sá-Nogueira, I

    2001-07-01

    The proteins involved in the utilization of L-arabinose by Bacillus subtilis are encoded by the araABDLMNPQ-abfA metabolic operon and by the araE/araR divergent unit. Transcription from the ara operon, araE transport gene, and araR regulatory gene is induced by L-arabinose and negatively controlled by AraR. The purified AraR protein binds cooperatively to two in-phase operators within the araABDLMNPQ-abfA (OR(A1) and OR(A2)) and araE (OR(E1) and OR(E2)) promoters and noncooperatively to a single operator in the araR (OR(R3)) promoter region. Here, we have investigated how AraR controls transcription from the ara regulon in vivo. A deletion analysis of the ara promoters region showed that the five AraR binding sites are the key cis-acting regulatory elements of their corresponding genes. Furthermore, OR(E1)-OR(E2) and OR(R3) are auxiliary operators for the autoregulation of araR and the repression of araE, respectively. Analysis of mutations designed to prevent cooperative binding of AraR showed that in vivo repression of the ara operon requires communication between repressor molecules bound to two properly spaced operators. This communication implicates the formation of a small loop by the intervening DNA. In an in vitro transcription system, AraR alone sufficed to abolish transcription from the araABDLMNPQ-abfA operon and araE promoters, strongly suggesting that it is the major protein involved in the repression mechanism of L-arabinose-inducible expression in vivo. The ara regulon is an example of how the architecture of the promoters is adapted to respond to the particular characteristics of the system, resulting in a tight and flexible control.

  17. Insecticidal Activity of Some Reducing Sugars Against the Sweet Potato Whitefly, Bemisia tabaci, Biotype B

    PubMed Central

    Hu, Jing S.; Gelman, Dale B.; Salvucci, Michael E.; Chen, Yan P.; Blackburn, Michael B.

    2010-01-01

    The effects of 16 sugars (arabinose, cellobiose, fructose, galactose, gentiobiose, glucose, inositol, lactose, maltose, mannitol (a sugar alcohol), mannose, melibiose, ribose, sorbitol, trehalose, and xylose) on sweet potato whitefly Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) survival were determined using in vitro bioassays. Of these sugars, arabinose, mannose, ribose, and xylose were strongly inhibitory to both nymphal and adult survival. When 10% mannose was added to the nymphal diet, 10.5%, 1.0%, and 0% developed to the 2nd, 3rd, and 4th instars, respectively. When 10% arabinose was added, 10.8% and 0% of the nymphs molted to the 2nd and 3rd instars, respectively. Addition of 10% xylose or ribose completely terminated B. tabaci development, preventing the molt to the 2nd instar. With decreasing sugar concentrations the inhibitory effect was significantly reduced. In tests using adults, arabinose, galactose, inositol, lactose, maltose, mannitol, mannose, melibiose, ribose, sorbitol, trehalose, and xylose significantly reduced mean day survival. Mortality rates were highest when arabinose, mannitol, mannose, ribose, or xylose was added to the diet. Mean day survival was less than 2 days when adults were fed on diet containing 10% of any one of these five sugars. When lower concentrations of sugars were used there was a decrease in mortality. Mode of action studies revealed that toxicity was not due to the inhibition of alpha glucosidase (converts sucrose to glucose and fructose) and/or trehalulose synthase (converts sucrose to trehalulose) activity. The result of agarose gel electrophoresis of RT-PCR products of bacterial endosymbionts amplified from RNA isolated from whiteflies fed with 10% arabinose, mannose, or xylose indicated that the concentration of endosymbionts in mycetomes was not affected by the toxic sugars. Experiments in which B. tabaci were fed on diets that contained radio-labeled sucrose, methionine or inulin and one or none (control) of

  18. residue and shunting pinholes

    NASA Astrophysics Data System (ADS)

    Gorji, Nima E.

    2014-09-01

    The present work considers two observable phenomena through the experimental fabrication and electrical characterization of the rf-sputtered CdS/CdTe thin film solar cells that extremely reduce the overall conversion efficiency of the device: CdCl2 residue on the surface of the semiconductor and shunting pinholes. The former happens through nonuniform treatment of the As-deposited solar cells before annealing at high temperature and the latter occurs by shunting pinholes when the cell surface is shunted by defects, wire-like pathways or scratches on the metallic back contact caused from the external contacts. Such physical problems may be quite common in the experimental activities and reduce the performance down to 4-5 % which leads to dismantle the device despite its precise fabrication. We present our electrical characterization on the samples that received wet CdCl2 surface treatment (uniform or nonuniform) and are damaged by the pinholes.

  19. Broad-host-range expression vectors that carry the L-arabinose-inducible Escherichia coli araBAD promoter and the araC regulator.

    PubMed

    Newman, J R; Fuqua, C

    1999-02-18

    We describe the development and analysis of broad-host-range (BHR) cloning vectors that carry the araC-PBAD controlled expression cassette from Escherichia coli. These plasmids are designed to facilitate l-arabinose-responsive control of target genes in a variety of Gram-negative bacterial hosts. BHR PBAD::lacZ fusions were used to analyze the utility of this controlled expression system in the plant pathogen Agrobacterium tumefaciens. In A. tumefaciens, the level of control afforded is significant, although less stringent than that observed in E. coli. The BHR PBAD vectors offer a useful alternative to currently used controlled expression systems, and can be employed in conjunction with other regulated promoters to simultaneously regulate expression of multiple genes. Addition of a variety of carbon sources, namely C4 acids and the anti-inducer d-fucose, allows modulation of l-arabinose induction. Activation of PBAD expression in A. tumefaciens requires a plasmid-borne copy of araC, and is not affected by endogenous regulators.

  20. Arabinose-induced binding of AraC protein to araI2 activates the araBAD operon promoter.

    PubMed

    Lee, N; Francklyn, C; Hamilton, E P

    1987-12-01

    The state of Escherichia coli araI DNA occupancy by AraC protein has been found to change from a two-turn to a four-turn occupancy upon the addition of the inducer arabinose. The araI site is separable into two contiguous regions, araI1 and araI2. araI1 binds both ligand-bound and ligand-free AraC protein, whereas araI2 binds AraC protein in the presence of arabinose only. A mutation in araI and a known mutation in araC led to the loss of araI2 binding, while binding to araI1 was unaffected. Both mutants failed to activate the promoter of the araBAD operon. We propose that araI2 occupancy by AraC protein leads to RNA polymerase recognition of the araBAD promoter and that araI1 acts as a switch mechanism allowing both the repressor and the activator forms of AraC protein to regulate the araBAD promoter.

  1. UDP-sugar pyrophosphorylase is essential for arabinose and xylose recycling, and is required during vegetative and reproductive growth in Arabidopsis.

    PubMed

    Geserick, Claudia; Tenhaken, Raimund

    2013-04-01

    Numerous nucleotide sugars are needed in plants to synthesize cell wall polymers and glycoproteins. The de novo synthesis of nucleotide sugars is of major importance. During growth, however, some polymers are broken down to monosaccharides. Reactivation of these sugars into nucleotide sugars occurs in two steps: first, by a substrate-specific sugar-1-kinase and, second, by UDP-sugar-pyrophosphorylase (USP), which has broad substrate specificity. A knock-out of the USP gene results in non-fertile pollen. By using various genetic complementation approaches we obtained a strong (>95%) knock-down line in USP that allowed us to investigate the physiological role of the enzyme during the life cycle. Mutant plants show an arabinose reduction in the cell wall, and accumulate mainly two sugars, arabinose and xylose, in the cytoplasm. The arabinogalactanproteins in usp mutants show no significant reduction in size. USP is also part of the myo-inositol oxygenation pathway to UDP-glucuronic acid; however, free glucuronic acid does not accumulate in cells, suggesting alternative conversion pathways of this monosaccharide. The knock-down plants are mostly sterile because of the improper formation of anthers and pollen sacks.

  2. Coexpression of β-D-galactosidase and L-arabinose isomerase in the production of D-tagatose: a functional sweetener.

    PubMed

    Zhan, Yijing; Xu, Zheng; Li, Sha; Liu, Xiaoliu; Xu, Lu; Feng, Xiaohai; Xu, Hong

    2014-03-19

    The functional sweetener, d-tagatose, is commonly transformed from galactose by l-arabinose isomerase. To make use of a much cheaper starting material, lactose, hydrolization, and isomerization are required to take place collaboratively. Therefore, a single-step method involving β-d-galactosidase was explored for d-tagatose production. The two vital genes, β-d-galactosidase gene (lacZ) and l-arabinose isomerase mutant gene (araA') were extracted separately from Escherichia coli strains and incorporated into E. coli simultaneously. This gave us E. coli-ZY, a recombinant producing strain capable of coexpressing the two key enzymes. The resulted cells exhibited maximum d-tagatose producing activity at 34 °C and pH 6.5 and in the presence of borate, 10 mM Fe(2+), and 1 mM Mn(2+). Further monitoring showed that the recombinant cells could hydrolyze more than 95% lactose and convert 43% d-galactose into d-tagatose. This research has verified the feasibility of single-step d-tagatose fermentation, thereby laying down the foundation for industrial usage of lactose.

  3. AraR, an l-Arabinose-Responsive Transcriptional Regulator in Corynebacterium glutamicum ATCC 31831, Exerts Different Degrees of Repression Depending on the Location of Its Binding Sites within the Three Target Promoter Regions

    PubMed Central

    Kuge, Takayuki; Teramoto, Haruhiko

    2015-01-01

    ABSTRACT In Corynebacterium glutamicum ATCC 31831, a LacI-type transcriptional regulator AraR, represses the expression of l-arabinose catabolism (araBDA), uptake (araE), and the regulator (araR) genes clustered on the chromosome. AraR binds to three sites: one (BSB) between the divergent operons (araBDA and galM-araR) and two (BSE1 and BSE2) upstream of araE. l-Arabinose acts as an inducer of the AraR-mediated regulation. Here, we examined the roles of these AraR-binding sites in the expression of the AraR regulon. BSB mutation resulted in derepression of both araBDA and galM-araR operons. The effects of BSE1 and/or BSE2 mutation on araE expression revealed that the two sites independently function as the cis elements, but BSE1 plays the primary role. However, AraR was shown to bind to these sites with almost the same affinity in vitro. Taken together, the expression of araBDA and araE is strongly repressed by binding of AraR to a single site immediately downstream of the respective transcriptional start sites, whereas the binding site overlapping the −10 or −35 region of the galM-araR and araE promoters is less effective in repression. Furthermore, downregulation of araBDA and araE dependent on l-arabinose catabolism observed in the BSB mutant and the AraR-independent araR promoter identified within galM-araR add complexity to regulation of the AraR regulon derepressed by l-arabinose. IMPORTANCE Corynebacterium glutamicum has a long history as an industrial workhorse for large-scale production of amino acids. An important aspect of industrial microorganisms is the utilization of the broad range of sugars for cell growth and production process. Most C. glutamicum strains are unable to use a pentose sugar l-arabinose as a carbon source. However, genes for l-arabinose utilization and its regulation have been recently identified in C. glutamicum ATCC 31831. This study elucidates the roles of the multiple binding sites of the transcriptional repressor AraR in the

  4. Soil water evaporation and crop residues

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Crop residues have value when left in the field and also when removed from the field and sold as a commodity. Reducing soil water evaporation (E) is one of the benefits of leaving crop residues in place. E was measured beneath a corn canopy at the soil suface with nearly full coverage by corn stover...

  5. An EBV recombinant deleted for residues 130-159 in EBNA3C can deregulate p53/Mdm2 and Cyclin D1/CDK6 which results in apoptosis and reduced cell proliferation

    PubMed Central

    El-Naccache, Darine W.; Robertson, Erle S.

    2016-01-01

    Epstein-Barr virus (EBV), a gamma herpes virus is associated with B-cell malignancies. EBNA-3C is critical for in vitro primary B-cell transformation. Interestingly, the N terminal domain of EBNA3C which contains residues 130–159, interacts with various cellular proteins, such as p53, Mdm2, CyclinD1/Cdk6 complex, and E2F1. In the current reverse genetics study, we deleted the residues 130-159 aa within EBNA3C open reading frame (ORF) by BACmid recombinant engineering methodology. Our experiments demonstrated that deletion of the 130-159 aa showed a reduction in cell proliferation. Also, this recombinant virus showed with higher infectivity of human peripheral blood mononuclear cells (PBMCs) compared to wild type EBV. PBMCs- infected with recombinant EBV deleted for 130-159 residues have differential expression patterns for the p53/Mdm2, CyclinD1/Cdk6 and pRb/E2F1 pathways compared to wild type EBV-infected PBMCs. PBMCs infected with recombinant virus showed increased apoptotic cell death which further resulted in activation of polymerase 1 (PARP1), an important contributor to apoptotic signaling. Interestingly, cells infected with this recombinant virus showed a dramatic decrease in chromosomal instability, indicated by the presence of increased multinucleation and micronucleation. In addition infection with recombinant virus have increased cells in G0/G1 phase and decreased cells in S-G2M phase when compared to wild type infected cells. Thus, these differences in signaling activities due to 29 amino acid residues of EBNA3C is of particular significance in deregulation of cell proliferation in EBV-infected cells. PMID:26908453

  6. Conversion of hemicellulose sugars catalyzed by formic acid: kinetics of the dehydration of D-xylose, L-arabinose, and D-glucose.

    PubMed

    Dussan, Karla; Girisuta, Buana; Lopes, Marystela; Leahy, James J; Hayes, Michael H B

    2015-04-24

    The pre-treatment of lignocellulosic biomass produces a liquid stream of hemicellulose-based sugars, which can be further converted to high-value chemicals. Formosolv pulping and the Milox process use formic acid as the fractionating agent, which can be used as the catalyst for the valorisation of hemicellulose sugars to platform chemicals. The objective of this study was to investigate the reaction kinetics of major components in the hemicelluloses fraction of biomass, that is, D-xylose, L-arabinose and D-glucose. The kinetics experiments for each sugar were performed at temperatures between 130 and 170 °C in various formic acid concentrations (10-64 wt %). The implications of these kinetic models on the selectivity of each sugar to the desired products are discussed. The models were used to predict the reaction kinetics of solutions that resemble the liquid stream obtained from the fractionation process of biomass using formic acid.

  7. Characterization of a recombinant L-fucose isomerase from Caldicellulosiruptor saccharolyticus that isomerizes L-fucose, D-arabinose, D-altrose, and L-galactose.

    PubMed

    Ju, Yo-Han; Oh, Deok-Kun

    2010-02-01

    A recombinant L-fucose isomerase from Caldicellulosiruptor saccharolyticus was purified as a single 68 kDa band with an activity of 76 U mg(-1). The molecular mass of the native enzyme was 204 kDa as a trimer. The maximum activity for L-fucose isomerization was at pH 7 and 75 degrees C in the presence of 1 mM Mn(2+). Its half-life at 70 degrees C was 6.1 h. For aldose substrates, the enzyme displayed activity in decreasing order for L-fucose, with a k (cat) of 11,910 min(-1) and a K (m) of 140 mM, D-arabinose, D-altrose, and L-galactose. These aldoses were converted to the ketoses L-fuculose, D-ribulose, D-psicose, and L-tagatose, respectively, with 24, 24, 85, 55% conversion yields after 3 h.

  8. A method for the production of D-tagatose using a recombinant Pichia pastoris strain secreting β-D-galactosidase from Arthrobacter chlorophenolicus and a recombinant L-arabinose isomerase from Arthrobacter sp. 22c

    PubMed Central

    2012-01-01

    Background D-Tagatose is a natural monosaccharide which can be used as a low-calorie sugar substitute in food, beverages and pharmaceutical products. It is also currently being tested as an anti-diabetic and obesity control drug. D-Tagatose is a rare sugar, but it can be manufactured by the chemical or enzymatic isomerization of D-galactose obtained by a β-D-galactosidase-catalyzed hydrolysis of milk sugar lactose and the separation of D-glucose and D-galactose. L-Arabinose isomerases catalyze in vitro the conversion of D-galactose to D-tagatose and are the most promising enzymes for the large-scale production of D-tagatose. Results In this study, the araA gene from psychrotolerant Antarctic bacterium Arthrobacter sp. 22c was isolated, cloned and expressed in Escherichia coli. The active form of recombinant Arthrobacter sp. 22c L-arabinose isomerase consists of six subunits with a combined molecular weight of approximately 335 kDa. The maximum activity of this enzyme towards D-galactose was determined as occurring at 52°C; however, it exhibited over 60% of maximum activity at 30°C. The recombinant Arthrobacter sp. 22c L-arabinose isomerase was optimally active at a broad pH range of 5 to 9. This enzyme is not dependent on divalent metal ions, since it was only marginally activated by Mg2+, Mn2+ or Ca2+ and slightly inhibited by Co2+ or Ni2+. The bioconversion yield of D-galactose to D-tagatose by the purified L-arabinose isomerase reached 30% after 36 h at 50°C. In this study, a recombinant Pichia pastoris yeast strain secreting β-D-galactosidase Arthrobacter chlorophenolicus was also constructed. During cultivation of this strain in a whey permeate, lactose was hydrolyzed and D-glucose was metabolized, whereas D-galactose was accumulated in the medium. Moreover, cultivation of the P. pastoris strain secreting β-D-galactosidase in a whey permeate supplemented with Arthrobacter sp. 22c L-arabinose isomerase resulted in a 90% yield of lactose hydrolysis, the

  9. Evolution of high-level ethambutol-resistant tuberculosis through interacting mutations in decaprenylphosphoryl-β-D-arabinose biosynthetic and utilization pathway genes.

    PubMed

    Safi, Hassan; Lingaraju, Subramanya; Amin, Anita; Kim, Soyeon; Jones, Marcus; Holmes, Michael; McNeil, Michael; Peterson, Scott N; Chatterjee, Delphi; Fleischmann, Robert; Alland, David

    2013-10-01

    To study the evolution of drug resistance, we genetically and biochemically characterized Mycobacterium tuberculosis strains selected in vitro for ethambutol resistance. Mutations in decaprenylphosphoryl-β-D-arabinose (DPA) biosynthetic and utilization pathway genes Rv3806c, Rv3792, embB and embC accumulated to produce a wide range of ethambutol minimal inhibitory concentrations (MICs) that depended on mutation type and number. Rv3806c mutations increased DPA synthesis, causing MICs to double from 2 to 4 μg/ml in a wild-type background and to increase from 16 to 32 μg/ml in an embB codon 306 mutant background. Synonymous mutations in Rv3792 increased the expression of downstream embC, an ethambutol target, resulting in MICs of 8 μg/ml. Multistep selection was required for high-level resistance. Mutations in embC or very high embC expression were observed at the highest resistance level. In clinical isolates, Rv3806c mutations were associated with high-level resistance and had multiplicative effects with embB mutations on MICs. Ethambutol resistance is acquired through the acquisition of mutations that interact in complex ways to produce a range of MICs, from those falling below breakpoint values to ones representing high-level resistance.

  10. [Screening of food-grade microorganisms for biotransformation of D-tagatose and cloning and expression of L-arabinose isomerase].

    PubMed

    Men, Yan; Zhu, Yueming; Guan, Yuping; Zhang, Tongcun; Izumori, Ken; Sun, Yuanxia

    2012-05-01

    L-Arabinose isomerase (L-AI) is an intracellular enzyme that catalyzes the reversible isomerization of D-galactose and D-tagatose. Given the widespread use of D-tagatose in the food industry, food-grade microorganisms and the derivation of L-AI for the production of D-tagatose is gaining increased attention. In the current study, food-grade strains from different foods that can convert D-galactose to D-tagatose were screened. According to physiological, biochemical, and 16S rDNA gene analyses, the selected strain was found to share 99% identity with Pediococcus pentosaceus, and was named as Pediococcus pentosaceus PC-5. The araA gene encoding L-AI from Pediococcus pentosaceus PC-5 was cloned and overexpressed in E. coli BL21. The yield of D-tagatose using D-galactose as the substrate catalyzed by the crude enzyme in the presence of Mn2+ was found to be 33% at 40 degrees C.

  11. Chemical improvement of chitosan-modified beads for the immobilization of Enterococcus faecium DBFIQ E36 L-arabinose isomerase through multipoint covalent attachment approach.

    PubMed

    Manzo, Ricardo M; de Sousa, Marylane; Fenoglio, Cecilia L; Gonçalves, Luciana Rocha Barro; Mammarella, Enrique J

    2015-10-01

    D-tagatose is produced from D-galactose by the enzyme L-arabinose isomerase (L-AI) in a commercially viable bioprocess. An active and stable biocatalyst was obtained by modifying chitosan gel structure through reaction with TNBS, D-fructose or DMF, among others. This led to a significant improvement in L-AI immobilization via multipoint covalent attachment approach. Synthetized derivatives were compared with commercial supports such as Eupergit(®) C250L and glyoxal-agarose. The best chitosan derivative for L-AI immobilization was achieved by reacting 4 % (w/v) D-fructose with 3 % (w/v) chitosan at 50 °C for 4 h. When compared to the free enzyme, the glutaraldehyde-activated chitosan biocatalyst showed an apparent activity of 88.4 U g (gel) (-1) with a 211-fold stabilization factor while the glyoxal-agarose biocatalyst gave an apparent activity of 161.8 U g (gel) (-1) with an 85-fold stabilization factor. Hence, chitosan derivatives were comparable to commercial resins, thus becoming a viable low-cost strategy to obtain high active L-AI insolubilized derivatives.

  12. TENORM: Coal Combustion Residuals

    EPA Pesticide Factsheets

    Burning coal in boilers to create steam for power generation and industrial applications produces a number of combustion residuals. Naturally radioactive materials that were in the coal mostly end up in fly ash, bottom ash and boiler slag.

  13. Antioxidant properties of roasted coffee residues.

    PubMed

    Yen, Wen-Jye; Wang, Bor-Sen; Chang, Lee-Wen; Duh, Pin-Der

    2005-04-06

    The antioxidant activity of roasted coffee residues was evaluated. Extraction with four solvents (water, methanol, ethanol, and n-hexane) showed that water extracts of roasted coffee residues (WERCR) produced higher yields and gave better protection for lipid peroxidation. WERCR showed a remarkable protective effect on oxidative damage of protein. In addition, WERCR showed scavenging of free radicals as well as the reducing ability and to bind ferrous ions, indicating that WERCR acts as both primary and secondary antioxidants. The HPLC analyses showed that phenolic acids (chlorogenic acid and caffeic acid) and nonphenolic compounds [caffeine, trigonelline, nicotinic acid, and 5-(hydroxymethyl)furfuraldehyde] remained in roasted coffee residues. These compounds showed a protective effect on a liposome model system. The concentrations of flavonoids and polyphenolic compounds in roasted coffee residues were 8,400 and 20,400 ppm, respectively. In addition, the Maillard reaction products (MRPs) remaining in roasted coffee residues were believed to show antioxidant activity. These data indicate that roasted coffee residues have excellent potential for use as a natural antioxidant source because the antioxidant compounds remained in roasted coffee residues.

  14. Residues of oxytetracycline in cultured rainbow trout.

    PubMed

    Sharafati-Chaleshtori, R; Mardani, G; Rafieian-Kopaei, M; Sharafati-Chaleshtori, A; Drees, F

    2013-11-01

    Nowadays, antibiotics are widely used in aquatic animals to control and treatment of infections or as food supplement for growth increase and animal output. With increasing use of veterinary drugs in food production, there is global consideration about the consumption of antimicrobial residues in aquatic foods and their effects on human health. This study was aimed to evaluate the Oxytetracycline (OTC) residues in Rainbow trout meat in Shahre-kord (Iran) markets before and after frying. After randomized collection of 50 samples of fish in Shahre-kord markets in a six months period were examined. The prepared samples were examined for OTC residues using HPLC analytical method before and after frying. Results showed that 3 (6%) of the samples before frying and 12 (24%) after frying were having lower than Maximum residual limits (MRLs) in Codex alimentarius. However, mean OTC residues before and after frying samples were above MRLs. The mean amounts of OTC were 2260 +/- 1090 and 1110 +/- 930 ng g(-1) before and after frying, respectively. These findings show that the frying of fish reduces OTC residual. Nevertheless, the usage of OTC should be reduced to an acceptable level in fishery industry.

  15. Quantifying logging residue - before the fact

    SciTech Connect

    Bones, J.T.

    1982-06-01

    Tree biomass estimation, which is being integrated into the U.S. Forest Service Renewable Resources Evaluation Program, will give foresters the ability to estimate the amount of logging residues they might expect from harvested treetops and branches and residual rough, rotten, and small trees before the actual harvest. With planning, and increased demand for such timber products as pulpwood and fuelwood, product recovery could be increased by up to 43 percent in softwood stands and 99% in hardwoods. Recovery levels affect gross product receipts and site preparation costs. An example of product recovery and residue generation is presented for three harvesting options in Pennsylvania hardwood stands. Under the whole-tree harvesting option, 46% more product was recovered than in single product harvesting, and logging residue levels were reduced by 58%.

  16. A glucose-insensitive T7 expression system for fully-induced expression of proteins at a subsaturating level of L-arabinose.

    PubMed

    Wang, Zei Wen; Lai, Cheng-Bon; Chang, Chih-Hsiang; Chiang, Chung-Jen; Chao, Yun-Peng

    2011-06-22

    The L-arabinose (Ara)-controlled T7 expression system was previously constructed by creation of an Escherichia coli BL21(BAD) strain. The production of recombinant proteins in this strain was stringently regulated and reached a high level upon induction with Ara. Nevertheless, this system is still associated with inherent problems of interference with glucose and of the all-or-nothing induction profile at a subsaturating level of Ara. In this study, these problems were circumvented by modifying the physiological traits of BL21(BAD) strain. This was followed by deletion of ptsG gene and the araFGH and araBAD operon. The former encodes the glucose transporter while the latter two gene operons produce proteins responsible for Ara uptake and catabolism. In addition, the expression of genomic araE (encodes the Ara transporter) was constitutively enhanced. The resulting strain was designated BAD-5. By expression of the faster degrader GFP(LAA) at a subsaturating level of Ara, 80% of BAD-5 strain was found visually bright in the presence or absence of glucose. A further analysis by flow cytometry showed a uniform distribution of GFP expression for BAD-5 strain. In marked contrast, BL21(BAD) strain exhibiting visual brightness was less than 10% of the cell population and remained dark in the presence of glucose. Moreover, a saturated level of luciferase from Renilla reniformis (Rluc) could be readily obtained in BAD-5 strain at 20 μM Ara regardless of glucose. Rluc in BL21(BAD) strain was produced in an Ara dose-dependent manner, and the protein production became arrested when glucose was present. Overall, it illustrates the usefulness of the improved system for overproduction of recombinant proteins in an efficient, homogeneous, and glucose-insensitive way.

  17. The solution structure of double helical arabino nucleic acids (ANA and 2'F-ANA): effect of arabinoses in duplex-hairpin interconversion.

    PubMed

    Martín-Pintado, Nerea; Yahyaee-Anzahaee, Maryam; Campos-Olivas, Ramón; Noronha, Anne M; Wilds, Christopher J; Damha, Masad J; González, Carlos

    2012-10-01

    We report here the first structure of double helical arabino nucleic acid (ANA), the C2'-stereoisomer of RNA, and the 2'-fluoro-ANA analogue (2'F-ANA). A chimeric dodecamer based on the Dickerson sequence, containing a contiguous central segment of arabino nucleotides, flanked by two 2'-deoxy-2'F-ANA wings was studied. Our data show that this chimeric oligonucleotide can adopt two different structures of comparable thermal stabilities. One structure is a monomeric hairpin in which the stem is formed by base paired 2'F-ANA nucleotides and the loop by unpaired ANA nucleotides. The second structure is a bimolecular duplex, with all the nucleotides (2'F-ANA and ANA) forming Watson-Crick base pairs. The duplex structure is canonical B-form, with all arabinoses adopting a pure C2'-endo conformation. In the ANA:ANA segment, steric interactions involving the 2'-OH substituent provoke slight changes in the glycosidic angles and, therefore, in the ANA:ANA base pair geometry. These distortions are not present in the 2'F-ANA:2'F-ANA regions of the duplex, where the -OH substituent is replaced by a smaller fluorine atom. 2'F-ANA nucleotides adopt the C2'-endo sugar pucker and fit very well into the geometry of B-form duplex, allowing for favourable 2'F···H8 interactions. This interaction shares many features of pseudo-hydrogen bonds previously observed in 2'F-ANA:RNA hybrids and in single 2'F-ANA nucleotides.

  18. One-step green synthesis of β-cyclodextrin/iron oxide-reduced graphene oxide nanocomposite with high supramolecular recognition capability: Application for vortex-assisted magnetic solid phase extraction of organochlorine pesticides residue from honey samples.

    PubMed

    Mahpishanian, Shokouh; Sereshti, Hassan

    2017-02-17

    In this research, β-cyclodextrin/iron oxide reduced graphene oxide hybrid nanostructure (β-CD/MRGO) with high water dispersability, excellent magnetic responsivity and molecular selectivity was prepared via a facile one step green strategy. The obtained nanomaterial was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, and vibrating sample magnetometry (VSM), which confirmed the modification of GO with β-CD and magnetic nanoparticles. The formation mechanism of β-CD/MRGO was also discussed. The prepared magnetic nanocomposite was then applied as adsorbent in the vortex-assisted magnetic solid phase extraction (MSPE) of 16 organochlorine pesticides (OCPs) from honey samples prior to gas chromatography-electron capture detection (GC-ECD) analysis. Optimum extraction conditions have been assessed with respect to vortex time, sample pH, adsorbent amount, and salt concentration as well as desorption conditions (type and volume of desorption solvent and desorption time). A good level of linearity (2-10,000ngkg(-1)) with satisfactory determination coefficients (R(2)>0.9966) and suitable precision (%RSDs less than 7.8) was obtained for OCPs under the optimal conditions. The limits of detection and quantification of the method were obtained in the sub-parts per trillion (ppt) to parts per trillion range (LOD: 0.52-3.21ngkg(-1); LOQ: 1.73-10.72ngkg(-1)) based on 3 and 10 signal to noise ratios, respectively. The MSPE method was successfully applied to analysis of OCPs in honey samples with recoveries in the range of 78.8% to 116.2% and RSDs (n=3) below 8.1%. The results demonstrated that β-CD/MRGO could exhibit good supramolecular recognition, enrichment capability and high extraction recoveries toward OCPs.

  19. Cellulose microfibril crystallinity is reduced by mutating C-terminal transmembrane region residues CESA1{sup A903V} and CESA3{sup T942I} of cellulose synthase

    SciTech Connect

    Harris, Darby; Corbin, Kendall; Wang, Tuo; Gutierrez, Ryan; Bertolo, Ana; Petti, Caroalberto; Smilgies, Detlef-M; Estevez, Jose Manuel; Bonetta, Dario; Urbanowicz, Breeanna; Ehrhardt, David; Somerville, Chris; Rose, Jocelyn; Hong, Mei; DeBolt, Seth

    2012-01-08

    The mechanisms underlying the biosynthesis of cellulose in plants are complex and still poorly understood. A central question concerns the mechanism of microfibril structure and how this is linked to the catalytic polymerization action of cellulose synthase (CESA). Furthermore, it remains unclear whether modification of cellulose microfibril structure can be achieved genetically, which could be transformative in a bio-based economy. To explore these processes in planta, we developed a chemical genetic toolbox of pharmacological inhibitors and corresponding resistance-conferring point mutations in the C-terminal transmembrane domain region of CESA1{sup A903V} and CESA3{sup T942I} in Arabidopsis thaliana. Using {sup 13}C solid-state nuclear magnetic resonance spectroscopy and X-ray diffraction, we show that the cellulose microfibrils displayed reduced width and an additional cellulose C4 peak indicative of a degree of crystallinity that is intermediate between the surface and interior glucans of wild type, suggesting a difference in glucan chain association during microfibril formation. Consistent with measurements of lower microfibril crystallinity, cellulose extracts from mutated CESA1{sup A903V} and CESA3{sup T942I} displayed greater saccharification efficiency than wild type. Using live-cell imaging to track fluorescently labeled CESA, we found that these mutants show increased CESA velocities in the plasma membrane, an indication of increased polymerization rate. Collectively, these data suggest that CESA1{sup A903V} and CESA3{sup T942I} have modified microfibril structure in terms of crystallinity and suggest that in plants, as in bacteria, crystallization biophysically limits polymerization.

  20. Alternative Bioenergy: Small Scale Pellet Production from Forest Residues

    NASA Astrophysics Data System (ADS)

    Cochran, Audra S.

    Forests can readily supply feedstock for alternative bioenergy production. Feedstock removal has the potential to benefit forest health and provide ecosystem services, while also generating profit for landowners, contractors and forest managers. However, many landowners are faced with the challenge of managing forest residuals to meet slash compliances and fire regulations. Currently, most residuals are burned or left on site to decompose. Every year, the north-central Idaho region produces over 16 million dry tons of unutilized forest residues. In a time where alternative energy sources are growing in demand, new approaches to utilize these residuals for bioenergy production are being examined. One approach is a portable, small-scale wood pellet mill that can be taken directly to the logging site. Utilizing forest residues for pellet production reduces residue burning and its potential negative impacts on air quality. This presentation focuses on the quality of wood pellets manufactured by a portable wood pellet mill utilizing various forms of forest residuals.

  1. Chemical Stabilization of Hanford Tank Residual Waste

    SciTech Connect

    Cantrell, Kirk J.; Um, Wooyong; Williams, Benjamin D.; Bowden, Mark E.; Gartman, Brandy N.; Lukens, Wayne W.; Buck, Edgar C.; Mausolf, Edward J.

    2014-03-01

    Three different chemical treatment methods were tested for their ability to stabilize residual waste from Hanford tank C-202 for reducing contaminant release (Tc, Cr, and U in particular). The three treatment methods tested were lime addition [Ca(OH)2], an in-situ Ceramicrete waste form based on chemically bonded phosphate ceramics, and a ferrous iron/goethite treatment. These approaches rely on formation of insoluble forms of the contaminants of concern (lime addition and ceramicrete) and chemical reduction followed by co-precipitation (ferrous iron/goethite incorporation treatment). The results have demonstrated that release of the three most significant mobile contaminants of concern from tank residual wastes can be dramatically reduced after treatment compared to contact with simulated grout porewater without treatment. For uranium, all three treatments methods reduced the leachable uranium concentrations by well over three orders of magnitude. In the case of uranium and technetium, released concentrations were well below their respective MCLs for the wastes tested. For tank C-202 residual waste, chromium release concentrations were above the MCL but were considerably reduced relative to untreated tank waste. This innovative approach has the potential to revolutionize Hanford’s tank retrieval process, by allowing larger volumes of residual waste to be left in tanks while providing an acceptably low level of risk with respect to contaminant release that is protective of the environment and human health. Such an approach could enable DOE to realize significant cost savings through streamlined retrieval and closure operations.

  2. Axial residual stresses in boron fibers

    NASA Technical Reports Server (NTRS)

    Behrendt, D. R.

    1978-01-01

    The axial residual stress distribution as a function of radius was determined from the fiber surface to the core including the average residual stress in the core. Such measurements on boron on tungsten (B/W) fibers show that the residual stresses for 102, 142, 203, and 366 micron diameter fibers were similar, being compressive at the surface and changing monotonically to a region of tensile within the boron. At approximately 25 percent of the original radius, the stress reaches a maximum tensile stress of about 860 mn/sq.m and then decreases to a compressive stress near the tungsten boride core. Data were presented for 203 micron diameter B/W fibers that show annealing above 900 C reduces the residual stresses. A comparison between 102 micron diameter B/W and boron on carbon (b/C) shows that the residual stresses were similar in the outer regions of the fibers, but that large differences near and in the core were observed. The effects of these residual stresses on the fracture of boron fibers were discussed.

  3. Effect of processing on 14C-chlorfenvinphos residues in maize oil and bioavailability of its cake residues on rats.

    PubMed

    Mahdy, F M; El-Maghraby, S I

    2010-05-01

    Maize seeds obtained from 14C-chlorfenvinphos treated plants contained 0.12% of the applied dose. The insecticide residues in crude oil, methanol and cake amounted to 10%, 6% and 69%, respectively of original residues inside the seeds. The 14C-activity in the crude oil could be a gradually reduced by the refining processes. The alkali treatment and bleaching steps are the most effective steps in these processes. The refined oil contained small amount of the 14C-residues originally present. The major residues in processed oil contain the parent compound, in addition to five metabolites of the insecticide. When rats fed the extracted seeds (cake), the bound residues were found to be considerably bioavailability. After feeding rats for five days with the cake, a substantial amount of 14C-residues was eliminated in the urine (59.5%), while about 20% excreted in the feces. About 15% of the radioactive residues were distributed among various organs.

  4. Structure of the O-specific polysaccharide from the lipopolysaccharide of Psychrobacter cryohalolentis K5(T) containing a 2,3,4-triacetamido-2,3,4-trideoxy-L-arabinose moiety.

    PubMed

    Kondakova, Anna N; Novototskaya-Vlasova, Kseniya A; Arbatsky, Nikolay P; Drutskaya, Marina S; Shcherbakova, Victoria A; Shashkov, Alexander S; Gilichinsky, David A; Nedospasov, Sergei A; Knirel, Yuriy A

    2012-12-28

    A novel constituent of bacterial polysaccharides, 2,3,4-triacetamido-2,3,4-trideoxy-L-arabinose, was found in the O-specific polysaccharide from the lipopolysaccharide of Psychrobacter cryohalolentis K5(T) and identified by 1D and 2D (1)H and (13)C NMR studies of the polysaccharide and a disaccharide obtained by solvolysis of the polysaccharide with triflic acid. The following structure of the branched polysaccharide was established by sugar analysis, triflic acid solvolysis, Smith degradation, and 2D NMR spectroscopy.

  5. The ASCE Residuals Transport Manual

    SciTech Connect

    Albertson, O.E.; Bizier, P.A.; Brown, J.; Koch, C.; Sadick, T.

    1999-07-01

    This presentation will highlight the ASCE Residuals Transport Manual, which has been published by ASCE this year. This document, which represents the state of the art in information on residuals transport, is designed to be used by both the active practitioner, as well as for instructional purposes. The authors will present the various chapters which cover the following topics: Conveyance of Water and Wastewater Residuals, Rheology, Sludge Characteristics, Quality and Quantity, Overview of Residuals Conveyance Devices, Pumping of Viscous Sludges and Slurries, Transport of Thickened Residuals, Conveyance of Dewatered Residuals, Transport of Granular and Compactable Residuals, and Case Studies. The Objective of the Transport Monograph is to summarize in one concise volume the general state of knowledge regarding residuals transport from both water and wastewater residuals. The presentation will cover each chapter and will review the pertinent information contained in the manual.

  6. Use of new methods for construction of tightly regulated arabinose and rhamnose promoter fusions in studies of the Escherichia coli phosphate regulon.

    PubMed

    Haldimann, A; Daniels, L L; Wanner, B L

    1998-03-01

    Escherichia coli genes regulated by environmental inorganic phosphate (Pi) levels form the phosphate (Pho) regulon. This regulation requires seven proteins, whose synthesis is under autogenous control, including response regulator PhoB, its partner, histidine sensor kinase PhoR, all four components of the Pi-specific transport (Pst) system (PstA, PstB, PstC, and PstS), and a protein of unknown function called PhoU. Here we examined the effects of uncoupling PhoB synthesis and PhoR synthesis from their normal controls by placing each under the tight control of the arabinose-regulated P(araB) promoter or the rhamnose-regulated P(rhaB) promoter. To do this, we made allele replacement plasmids that may be generally useful for construction of P(araB) or P(rhaB) fusions and for recombination of them onto the E. coli chromosome at the araCBAD or rhaRSBAD locus, respectively. Using strains carrying such single-copy fusions, we showed that a P(rhaB) fusion is more tightly regulated than a P(araB) fusion in that a P(rhaB)-phoR+ fusion but not a P(araB)-phoR+ fusion shows a null phenotype in the absence of its specific inducer. Yet in the absence of induction, both P(araB)-phoB+ and P(rhaB)-phoB+ fusions exhibit a null phenotype. These data indicate that less PhoR than PhoB is required for transcriptional activation of the Pho regulon, which is consistent with their respective modes of action. We also used these fusions to study PhoU. Previously, we had constructed strains with precise delta phoU mutations. However, we unexpectedly found that such delta phoU mutants have a severe growth defect (P. M. Steed and B. L. Wanner, J. Bacteriol. 175:6797-6809, 1993). They also readily give rise to compensatory mutants with lesions in phoB, phoR, or a pst gene, making their study particularly difficult. Here we found that, by using P(araB)-phoB+, P(rhaB)-phoB+, or P(rhaB)-phoR+ fusions, we were able to overcome the extremely deleterious growth defect of a Pst+ delta phoU mutant. The

  7. Catalytic combustion with incompletely vaporized residual fuel

    NASA Technical Reports Server (NTRS)

    Rosfjord, T. J.

    1981-01-01

    Catalytic combustion of fuel lean mixtures of incompletely vaporized residual fuel and air was investigated. The 7.6 cm diameter, graded cell reactor was constructed from zirconia spinel substrate and catalyzed with a noble metal catalyst. Streams of luminous particles exited the rector as a result of fuel deposition and carbonization on the substrate. Similar results were obtained with blends of No. 6 and No. 2 oil. Blends of shale residual oil and No. 2 oil resulted in stable operation. In shale oil blends the combustor performance degraded with a reduced degree of fuel vaporization. In tests performed with No. 2 oil a similar effect was observed.

  8. Assessing crop residue cover as scene moisture conditions change

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Crop residue or plant litter is the portion of a crop left in the field after harvest. Crop residues on the soil surface provide a first line of defense against water and wind erosion and reduce the amounts of soil, nutrients, and pesticides that reach streams and rivers. Thus, quantification of cro...

  9. 78 FR 32235 - Availability of Compliance Guide for Residue Prevention and Response to Comments

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-29

    ... producer history; (2) buy animals from producers who have a history of providing residue-free animals and... target outreach on residue avoidance to reduce the probability that a repeat violation would...

  10. Residual stresses in material processing

    SciTech Connect

    Kozaczek, K.J.; Watkins, T.R.; Hubbard, C.R.; Wang, Xun-Li; Spooner, S.

    1994-09-01

    Material manufacturing processes often introduce residual stresses into the product. The residual stresses affect the properties of the material and often are detrimental. Therefore, the distribution and magnitude of residual stresses in the final product are usually an important factor in manufacturing process optimization or component life prediction. The present paper briefly discusses the causes of residual stresses. It then adresses the direct, nondestructive methods of residual stress measurement by X-ray and neutron diffraction. Examples are presented to demonstrate the importance of residual stress measurement in machining and joining operations.

  11. Reducing Phosphorus Runoff from Biosolids with Water Treatment Residuals

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A large fraction of the biosolids produced in the U.S. are placed in landfills or incinerated to avoid potential water quality problems associated with non-point source phosphorus (P) runoff. The objective of this study was to determine the effect of various chemical amendments on P runoff from bi...

  12. SRC Residual fuel oils

    DOEpatents

    Tewari, Krishna C.; Foster, Edward P.

    1985-01-01

    Coal solids (SRC) and distillate oils are combined to afford single-phase blends of residual oils which have utility as fuel oils substitutes. The components are combined on the basis of their respective polarities, that is, on the basis of their heteroatom content, to assure complete solubilization of SRC. The resulting composition is a fuel oil blend which retains its stability and homogeneity over the long term.

  13. Sustainable System for Residual Hazards Management

    SciTech Connect

    Kevin M. Kostelnik; James H. Clarke; Jerry L. Harbour

    2004-06-01

    Hazardous, radioactive and other toxic substances have routinely been generated and subsequently disposed of in the shallow subsurface throughout the world. Many of today’s waste management techniques do not eliminate the problem, but rather only concentrate or contain the hazardous contaminants. Residual hazards result from the presence of hazardous and/or contaminated material that remains on-site following active operations or the completion of remedial actions. Residual hazards pose continued risk to humans and the environment and represent a significant and chronic problem that require continuous longterm management (i.e. >1000 years). To protect human health and safeguard the natural environment, a sustainable system is required for the proper management of residual hazards. A sustainable system for the management of residual hazards will require the integration of engineered, institutional and land-use controls to isolate residual contaminants and thus minimize the associated hazards. Engineered controls are physical modifications to the natural setting and ecosystem, including the site, facility, and/or the residual materials themselves, in order to reduce or eliminate the potential for exposure to contaminants of concern (COCs). Institutional controls are processes, instruments, and mechanisms designed to influence human behavior and activity. System failure can involve hazardous material escaping from the confinement because of system degradation (i.e., chronic or acute degradation) or by externalintrusion of the biosphere into the contaminated material because of the loss of institutional control. An ongoing analysis of contemporary and historic sites suggests that the significance of the loss of institutional controls is a critical pathway because decisions made during the operations/remedial action phase, as well as decisions made throughout the residual hazards management period, are key to the longterm success of the prescribed system. In fact

  14. Preparation of Nucleosides Derived from 2-Nitroimidazole and d-Arabinose, d-Ribose, and d-Galactose by the Vorbrüggen Method and Their Conversion to Potential Precursors for Tracers To Image Hypoxia

    PubMed Central

    2011-01-01

    2-Nitroimidazole was silylated using hexaethyldisilazane and then reacted with 1-O-acetyl derivatives of d-arabinose, d-ribose, and d-galactose in acetonitrile at mild temperatures (−20 °C to rt), catalyzed by triethylsilyl triflate (Vorbrüggen conditions). The α-anomer was formed in the former case and the β-anomers in the latter two cases (highly) selectively. When d-arabinose and d-ribose were silylated with tert-butyldiphenylsilyl chloride in pyridine at the hydroxyl groups at C-5 and acetylated at the other ones in a one-pot reaction, mixtures of anomeric 1-O-acetyl derivatives were obtained. These were coupled by the Vorbrüggen method and then deblocked at C-5 and tosylated to give precursors for tracers to image hypoxia in four steps without using Hg(CN)2 necessary for other methods. The Vorbrüggen conditions enable a shorter route to azomycin nucleoside analogues than the previous coupling procedures. PMID:21905640

  15. CHARACTERIZING RESIDUE TRANSFER EFFICIENCIES USING A FLUORESCENT IMAGING TECHNIQUE

    EPA Science Inventory

    To reduce the uncertainty associated with current estimates of children's exposure to pesticides by dermal contact and indirect ingestion, residue transfer data are required. Prior to conducting exhaustive studies, a screening study to identify the important parameters for chara...

  16. Nitrogen deposition promotes the production of new fungal residues but retards the decomposition of old residues in forest soil fractions.

    PubMed

    Griepentrog, Marco; Bodé, Samuel; Boeckx, Pascal; Hagedorn, Frank; Heim, Alexander; Schmidt, Michael W I

    2014-01-01

    Atmospheric nitrogen (N) deposition has frequently been observed to increase soil carbon (C) storage in forests, but the underlying mechanisms still remain unclear. Changes in microbial community composition and substrate use are hypothesized to be one of the key mechanisms affected by N inputs. Here, we investigated the effects of N deposition on amino sugars, which are used as biomarkers for fungal- and bacterial-derived microbial residues in soil. We made use of a 4-year combined CO2 enrichment and N deposition experiment in model forest ecosystems, providing a distinct (13) C signal for 'new' and 'old' C in soil organic matter and microbial residues measured in density and particle-size fractions of soils. Our hypothesis was that N deposition decreases the amount of fungal residues in soils, with the new microbial residues being more strongly affected than old residues. The soil fractionation showed that organic matter and microbial residues are mainly stabilized by association with soil minerals in the heavy and fine fractions. Moreover, the bacterial residues are relatively enriched at mineral surfaces compared to fungal residues. The (13) C tracing indicated a greater formation of fungal residues compared to bacterial residues after 4 years of experiment. In contradiction to our hypotheses, N deposition significantly increased the amount of new fungal residues in bulk soil and decreased the decomposition of old microbial residues associated with soil minerals. The preservation of old microbial residues could be due to decreased N limitation of microorganisms and therefore a reduced dependence on organic N sources. This mechanism might be especially important in fine heavy fractions with low C/N ratios, where microbial residues are effectively protected from decomposition by association with soil minerals.

  17. Herbicide retention in soil as affected by sugarcane mulch residue.

    PubMed

    Selim, H M; Zhou, L; Zhu, H

    2003-01-01

    Reducing surface and subsurface losses of herbicides in the soil and thus their potential contamination of water resources is a national concern. This study evaluated the effectiveness of sugarcane (Saccharum spp.) residue (mulch cover) in reducing nonpoint-source contamination of applied herbicides from sugarcane fields. Specifically, the effect of mulch residue on herbicide retention was quantified. Two main treatments were investigated: a no-till treatment and a no-mulch treatment. The amounts of extractable atrazine [2-chloro-4-(isopropylamino)-6-ethylamino-s-triazine], metribuzin [4-amino-6-(1,1-dimethylethyl)-3-(methylthio)-1,2,4-triazin-5(4H)-one], and pendimethalin [N-(ethylpropyl)-3,4-dimethyl-2,6-dinitroaniline] from the mulch residue and the surface soil layer were quantified during the 1999 and 2000 growing seasons. Significant amounts of applied herbicides were intercepted by the mulch residue. Extractable concentrations were at least one order of magnitude higher for the mulch residue compared with that retained by the soil. Moreover, the presence of mulch residue on the sugarcane rows was highly beneficial in minimizing runoff losses of the herbicides applied. When the residue was not removed, a reduction in runoff-effluent concentrations, as much as 50%, for atrazine and pendimethalin was realized. Moreover, the presence of mulch residue resulted in consistently lower estimates for rates of decay or disappearance of atrazine and pendimethalin in the surface soil.

  18. Using ASTER image for soybean plant residue coverage estimation

    NASA Astrophysics Data System (ADS)

    Yao, Haibo; Lewis, David; Kincaid, Russell

    2006-10-01

    Soil erosion and its related runoff is a serious problem in U.S. agriculture. USDA has classified 27% of U.S. agricultural land as being highly erodible. Because of the erosion, rivers, lakes, and water table are contaminated due to the agriculture chemicals such as nitrogen, phosphorus, and pesticides contained in the runoff water. This is a serious environmental problem nationwide. It is well recognized that residue coverage on the soil surface can reduce soil erosion. The objective of this paper was to explore the potential of using ASTER data for soybean plant residue cover estimation. In the spring of 2004, personnel from Natural Resource Conservation Service (NRCS) and Institute for Technology Development (ITD) did a traditional windshield survey in three Indiana Counties, Wabash, Huntington, and Grant. Fields with greater than 30% residue cover were classified as conservation tillage (no till); those with 16-30% residue cover as reduced tillage; and those with less than 15% residue cover as traditional tillage. ASTER data was collected over the study sites on April 14, 2004. Spectral information was extracted from the ASTER image for statistical analysis. Field values for various indices were calculated from the reflectance data. Residue coverage estimation from the survey was used as the ground truth for the field. Analysis was performed to determine the capability of ASTER data to identify crop residue coverage. The initial results indicated that ASTER imagery has moderate capability to identify residue coverage - or tillage practice within the soybean fields.

  19. Application of sedimentary carbohydrate residues in a study of organic facies and natural gas occurrences

    NASA Astrophysics Data System (ADS)

    Swain, F. M.

    Recent aquatic environments and resulting organic facies can be characterized by types and amounts of carbohydrate residues. Characteristics are based on source organisms, degree and type of degradation, and reactions with associated compounds in the mineral-kerogen-humus complex. Selected modern environments are typified by the following presently known carbohydrate suites: (1) deep sea, mid-Pacific, mid-Atlantic Oceans—glucose, galactose, furfurals, low total carbohydrates (TC); (2) deep gulf, Gulf of California—glu, gal, xylose, mannose, furfurals, moderate to high TC; (3) continental shelf, eastern North America—glu, xyl, gal, furfurals, high TC; (5) oligotrophic lake, Minnesota—furfurals, low TC; (6) eutrophic lake, Minnesota—glu, xyl, arabinose, gal, rhamnose, man, ribose, furfurals, glucuronic acid, high TC; (7) bog, Minnesota—glu, ara, xyl, gal, man, rib, very high TC. Polysaccharides are rare to absent in modern deep sea deposits but have been found in Lower Quaternary and younger deep gulf sediments. Cellulose, alpha- and beta-amylose and laminaran are common in shallow marine and lacustrine sediments. Methane, derived from both terrestrial and aquatic higher plant residues is high in yield in freshwater marshes and bogs and in eutrophic lake sediments, moderate in salt-water marshes and estuaries and relatively low in offshore marine sediments. Nitrogen and carbon dioxide are the commonest non-hydrocarbon gases. In many samples studied, xylans appear to predominate over other plant polysaccharide as methane sources. Carbohydrate residues in ancient rocks, based on examples from North America, show a tentative, but as yet poorly investigated, relationship to environmental organic facies and should prove to be useful in natural gas exploration.

  20. Recycling of auto shredder residue.

    PubMed

    Nourreddine, Menad

    2007-01-31

    Currently, about 75% of end-of-life vehicle's (ELV) total weight is recycled in EU countries. The remaining 25%, which is called auto shredder residues (ASR) or auto fluff, is disposed of as landfill because of its complexity. It is a major challenge to reduce this percentage of obsolete cars. The European draft directive states that by the year 2006, only 15% of the vehicle's weight can be disposed of at landfill sites and by 2015, this will be reduced to 5%. The draft directive states that a further 10% can be incinerated. The quantities of shredder fluff are likely to increase in the coming years. This is because of the growing number of cars being scrapped, coupled with the increase in the amount of plastics used in cars. In Sweden, some current projects are focusing on recycling of ASR material. In this paper some different alternatives for using this material are reported. The hypothetical injection of ASR into a blast furnace concentrating on ASR's effect to some blast furnace (BF) parameters has been completed using a blast furnace mass balance model. As a result, in principle, ASR can be used as reducing agent in the BF process if certain conditions are met. The particle size of ASR material must be controlled to ensure optimal gasification of the material in the raceway. Regarding the chemical composition of ASR, the non-ferrous content can affect the pig iron quality, which is difficult to rectify at a later point. The most attractive recycling alternative is to use the products obtained from pyrolysis of ASR in appropriate metallurgical processes.

  1. Impact of Corn Residue Removal on Crop and Soil Productivity

    NASA Astrophysics Data System (ADS)

    Johnson, J. M.; Wilhelm, W. W.; Hatfield, J. L.; Voorhees, W. B.; Linden, D.

    2003-12-01

    Over-reliance on imported fuels, increasing atmospheric levels of greenhouses and sustaining food production for a growing population are three of the most important problems facing society in the mid-term. The US Department of Energy and private enterprise are developing technology necessary to use high cellulose feedstock, such as crop residues, for ethanol production. Based on production levels, corn (Zea mays L.) residue has potential as a biofuel feedstock. Crop residues are a renewable and domestic fuel source, which can reduce the rate of fossil fuel use (both imported and domestic) and provide an additional farm commodity. Crop residues protect the soil from wind and water erosion, provide inputs to form soil organic matter (a critical component determining soil quality) and play a role in nutrient cycling. Crop residues impact radiation balance and energy fluxes and reduce evaporation. Therefore, the benefits of using crop residues as fuel, which removes crop residues from the field, must be balanced against negative environmental impacts (e.g. soil erosion), maintaining soil organic matter levels, and preserving or enhancing productivity. All ramifications of new management practices and crop uses must be explored and evaluated fully before an industry is established. There are limited numbers of long-term studies with soil and crop responses to residue removal that range from negative to negligible. The range of crop and soil responses to crop residue removal was attributed to interactions with climate, management and soil type. Within limits, corn residue can be harvested for ethanol production to provide a renewable, domestic source of energy feedstock that reduces greenhouse gases. Removal rates must vary based on regional yield, climatic conditions and cultural practices. Agronomists are challenged to develop a protocol (tool) for recommending maximum permissible removal rates that ensure sustained soil productivity.

  2. Residue harvest effects on corn response to applied N and yield

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Corn (Zea mays L.) residue harvest is common in Nebraska, primarily for feeding of beef cattle. Applied N immobilization is expected to be less with residue harvest due to reduced microbial activity for digestion of high CN organic material. Residue reduction may affect subsequent crop yield and res...

  3. Residue harvest effects on irrigated, no-till corn yield and nitrogen response

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Corn (Zea mays L.) residue harvest is common in Nebraska, primarily for feeding of beef cattle. Applied N immobilization is expected to be less with residue harvest due to reduced microbial activity for digestion of high CN organic material. Residue reduction may affect subsequent crop yield and res...

  4. Nonlinearity-reduced interferometer

    NASA Astrophysics Data System (ADS)

    Wu, Chien-ming

    2007-12-01

    Periodic nonlinearity is a systematic error limiting the accuracy of displacement measurements at the nanometer level. It results from many causes such as the frequency mixing, polarization mixing, polarization-frequency mixing, and the ghost reflections. An interferometer having accuracy in displacement measurement of less than one-nanometer is necessary in nanometrology. To meet the requirement, the periodic nonlinearity should be less than deep sub-nanometer. In this paper, a nonlinearity-reduced interferometry has been proposed. Both the linear- and straightness-interferometer were tested. The developed interferometer demonstrated of a residual nonlinearity less than 25 pm.

  5. Determination of Pesticides Residues in Cucumbers Grown in Greenhouse and the Effect of Some Procedures on Their Residues

    PubMed Central

    LEILI, Mostafa; PIRMOGHANI, Amin; SAMADI, Mohammad Taghi; SHOKOOHI, Reza; ROSHANAEI, Ghodratollah; POORMOHAMMADI, Ali

    2016-01-01

    Background: The objective of this study was to determine the residual concentrations of ethion and imidacloprid in cucumbers grown in greenhouse. The effect of some simple processing procedures on both ethion and imidacloprid residues were also studied. Methods: Ten active greenhouses that produce cucumber were randomly selected. Ethion and imidacloprid as the most widely used pesticides were measured in cucumber samples of studied greenhouses. Moreover, the effect of storing, washing, and peeling as simple processing procedures on both ethion and imidacloprid residues were investigated. Results: One hour after pesticide application; the maximum residue levels (MRLs) of ethion and imidacloprid were higher than that of Codex standard level. One day after pesticide application, the levels of pesticides were decreased about 35 and 31% for ethion and imidacloprid, respectively, which still were higher than the MRL. Washing procedure led to about 51 and 42.5% loss in ethion and imidacloprid residues, respectively. Peeling procedure also led to highest loss of 93.4 and 63.7% in ethion and imidacloprid residues, respectively. The recovery for both target analytes was in the range between 88 and 102%. Conclusion: The residue values in collected samples one hour after pesticides application were higher than standard value. The storing, washing, and peeling procedures lead to the decrease of pesticide residues in greenhouse cucumbers. Among them, the peeling procedure has the greatest impact on residual reduction. Therefore, these procedures can be used as simple and effective processing techniques for reducing and removing pesticides from greenhouse products before their consumption. PMID:28032066

  6. Selenium speciation in flue desulfurization residues.

    PubMed

    Zhong, Liping; Cao, Yan; Li, Wenying; Xie, Kechang; Pan, Wei-Ping

    2011-01-01

    Flue gas from coal combustion contains significant amounts of volatile selenium (Se). The capture of Se in the flue gas desulfurization (FGD) scrubber unit has resulted in a generation of metal-laden residues. It is important to determine Se speciation to understand the environmental impact of its disposal. A simple method has been developed for selective inorganic Se(IV), Se(VI) and organic Se determination in the liquid-phase FGD residues by hydride generation atomic fluorescence spectrometry (AFS). It has been determined that Se(IV), Se(VI) and organic Se can be accurately determined with detection limits (DL) of 0.05, 0.06 and 0.06 microg/L, respectively. The accuracy of the proposed method was evaluated by analyzing the certified reference material, NIST CRM 1632c, and also by analyzing spiked tap-water samples. Analysis indicates that the concentration of Se is high in FGD liquid residues and primarily exists in a reduced state as selenite (Se(IV)). The toxicity of Se(IV) is the strongest of all Se species. Flue gas desulfurization residues pose a serious environmental risk.

  7. Materials recovery from shredder residues

    SciTech Connect

    Daniels, E. J.; Jody, B. J.; Pomykala, J., Jr.

    2000-07-24

    Each year, about five (5) million ton of shredder residues are landfilled in the US. Similar quantities are landfilled in Europe and the Pacific Rim. Landfilling of these residues results in a cost to the existing recycling industry and also represents a loss of material resources that are otherwise recyclable. In this paper, the authors outline the resources recoverable from typical shredder residues and describe technology that they have developed to recover these resources.

  8. Reducing the atmospheric impact of wet slaking

    SciTech Connect

    B.D. Zubitskii; G.V. Ushakov; B.G. Tryasunov; A.G.Ushakov

    2009-05-15

    Means of reducing the atmospheric emissions due to the wet slaking of coke are considered. One option, investigated here, is to remove residual active silt and organic compounds from the biologically purified wastewater sent for slaking, by coagulation and flocculation.

  9. Microwave emission and crop residues

    NASA Technical Reports Server (NTRS)

    Jackson, Thomas J.; O'Neill, Peggy E.

    1991-01-01

    A series of controlled experiments were conducted to determine the significance of crop residues or stubble in estimating the emission of the underlying soil. Observations using truck-mounted L and C band passive microwave radiometers showed that for dry wheat and soybeans the dry residue caused negligible attenuation of the background emission. Green residues, with water contents typical of standing crops, did have a significant effect on the background emission. Results for these green residues also indicated that extremes in plant structure, as created using parallel and perpendicular stalk orientations, can cause very large differences in the degree of attenuation.

  10. Residual stress alleviation of aircraft metal structures reinforced with filamentary composites

    NASA Technical Reports Server (NTRS)

    Kelly, J. B.; June, R. R.

    1973-01-01

    Methods to eliminate or reduce residual stresses in aircraft metal structures reinforced by filamentary composites are discussed. Residual stress level reductions were achieved by modifying the manufacturing procedures used during adhesive bonding. The residual stress alleviation techniques involved various forms of mechanical constraint which were applied to the components during bonding. Nine methods were evaluated, covering a wide range in complexity. All methods investigated during the program affected the residual stress level. In general, residual stresses were reduced by 70 percent or more from the stress level produced by conventional adhesive bonding procedures.

  11. Syntheses of 2-keto-3-deoxy-D-xylonate and 2-keto-3-deoxy-L-arabinonate as stereochemical probes for demonstrating the metabolic promiscuity of Sulfolobus solfataricus towards D-xylose and L-arabinose.

    PubMed

    Archer, Robert M; Royer, Sylvain F; Mahy, William; Winn, Caroline L; Danson, Michael J; Bull, Steven D

    2013-02-18

    Practical syntheses of 2-keto-3-deoxy-D-xylonate (D-KDX) and 2-keto-3-deoxy-L-arabinonate (L-KDA) that rely on reaction of the anion of ethyl 2-[(tert-butyldimethylsilyl)oxy]-2-(dimethoxy phosphoryl) acetate with enantiopure glyceraldehyde acetonide, followed by global deprotection of the resultant O-silyl-enol esters, have been developed. This has enabled us to confirm that a 2-keto-3-deoxy-D-gluconate aldolase from the archaeon Sulfolobus solfataricus demonstrates good activity for catalysis of the retro-aldol cleavage of both these enantiomers to afford pyruvate and glycolaldehyde. The stereochemical promiscuity of this aldolase towards these enantiomeric aldol substrates confirms that this organism employs a metabolically promiscuous pathway to catabolise the C5-sugars D-xylose and L-arabinose.

  12. Glove accumulation of pesticide residues for strawberry harvester exposure assessment.

    PubMed

    Li, Yanhong; Chen, Li; Chen, Zhenshan; Coehlo, Joe; Cui, Li; Liu, Yu; Lopez, Terry; Sankaran, Gayatri; Vega, Helen; Krieger, Robert

    2011-06-01

    We investigated the accumulation of pesticide residues on rubber latex gloves that are used by strawberry harvesters to protect their skin, reduce pesticide exposure and promote food safety. Gloves accumulated residues of 16 active ingredients including azoxystrobin, bifenthrin, boscalid, captan, cyprodinil, fenhexamid, fenpropathrin, fludioxonil, hexythiazox, malathion, methomyl, naled, propiconazole, pyraclostrobin, quinoline, and quinoxyfen at different times. Glove residue accumulation (t(½) 2.8-3.7 d) was very similar to the dissipation of DFRs (t(½) 2.1-3.0 d) during the first 3 weeks after malathion applications. Dermal malathion dose was 0.2 mg/kg at the preharvest interval and declined to trace levels during the following 3 months. Glove accumulation of malathion indicated trace surface residue availability and was used to assess the relationship between dislodgable foliar residues and potential hand exposure.

  13. Laundering as decontamination of apparel fabrics: residues of pesticides from six chemical classes.

    PubMed

    Nelson, C; Laughlin, J; Kim, C; Rigakis, K; Raheel, M; Scholten, L

    1992-07-01

    Research on reducing the level of pesticide residue on a textile substrate has examined many variables under many different conditions. This study controlled fiber type and the use of prewash product in an examination of residue levels for a number of pesticides in different pesticide classes. For all pesticides examined, the use of prewash lowered pesticide residues regardless of fiber type. Differences in pesticide residue level attributable to fiber type were not consistent.

  14. On tide-induced lagrangian residual current and residual transport: 1. Lagrangian residual current

    USGS Publications Warehouse

    Feng, Shizuo; Cheng, Ralph T.; Pangen, Xi

    1986-01-01

    Residual currents in tidal estuaries and coastal embayments have been recognized as fundamental factors which affect the long-term transport processes. It has been pointed out by previous studies that it is more relevant to use a Lagrangian mean velocity than an Eulerian mean velocity to determine the movements of water masses. Under weakly nonlinear approximation, the parameter k, which is the ratio of the net displacement of a labeled water mass in one tidal cycle to the tidal excursion, is assumed to be small. Solutions for tides, tidal current, and residual current have been considered for two-dimensional, barotropic estuaries and coastal seas. Particular attention has been paid to the distinction between the Lagrangian and Eulerian residual currents. When k is small, the first-order Lagrangian residual is shown to be the sum of the Eulerian residual current and the Stokes drift. The Lagrangian residual drift velocity or the second-order Lagrangian residual current has been shown to be dependent on the phase of tidal current. The Lagrangian drift velocity is induced by nonlinear interactions between tides, tidal currents, and the first-order residual currents, and it takes the form of an ellipse on a hodograph plane. Several examples are given to further demonstrate the unique properties of the Lagrangian residual current.

  15. Residue-based scattering factors.

    PubMed

    Xu, Hongliang

    2016-11-01

    A glob is defined as a group of atoms in the crystal which can be chosen in various ways. Globs themselves can be used as scattering elements in the theory of structure determination, just as atoms are used at present. In this paper, amino-acid residues are chosen to form globs and empirical formulas for residue-based scattering factors have been developed.

  16. A manual for implementing residual radioactive material guidelines

    SciTech Connect

    Gilbert, T.L.; Yu, C.; Yuan, Y.C.; Zielen, A.J.; Jusko, M.J.; Wallo, A. III

    1989-06-01

    This manual presents information for implementing US Department of Energy (DOE) guidelines for residual radioactive material at sites identified by the Formerly Utilized Sites Remedial Action Program (FUSRAP) and the Surplus Facilities Management Program (SFMP). It describes the analysis and models used to derive site-specific guidelines for allowable residual concentrations of radionuclides in soil and the design and use of the RESRAD computer code for calculating guideline values. It also describes procedures for implementing DOE policy for reducing residual radioactivity to levels that are as low as reasonably achievable. 36 refs., 16 figs, 22 tabs.

  17. Sugarcane rice residue biochars and their applications

    NASA Astrophysics Data System (ADS)

    Wang, J. J.

    2014-12-01

    production, and reduced greenhouse gas emission. Overall, the conversion of sugarcane harvest residue to biochar as soil amendment improves sugarcane production for both agronomic and environmental benefits. Sugarcane residue biochar also showed the potential of other environmental use for remediation of petroleum hydrocarbons.

  18. RESIDUAL RISK ASSESSMENT: MAGNETIC TAPE ...

    EPA Pesticide Factsheets

    This document describes the residual risk assessment for the Magnetic Tape Manufacturing source category. For stationary sources, section 112 (f) of the Clean Air Act requires EPA to assess risks to human health and the environment following implementation of technology-based control standards. If these technology-based control standards do not provide an ample margin of safety, then EPA is required to promulgate addtional standards. This document describes the methodology and results of the residual risk assessment performed for the Magnetic Tape Manufacturing source category. The results of this analyiss will assist EPA in determining whether a residual risk rule for this source category is appropriate.

  19. RESIDUAL RISK ASSESSMENT: ETHYLENE OXIDE ...

    EPA Pesticide Factsheets

    This document describes the residual risk assessment for the Ethylene Oxide Commercial Sterilization source category. For stationary sources, section 112 (f) of the Clean Air Act requires EPA to assess risks to human health and the environment following implementation of technology-based control standards. If these technology-based control standards do not provide an ample margin of safety, then EPA is required to promulgate addtional standards. This document describes the methodology and results of the residual risk assessment performed for the Ethylene Oxide Commercial Sterilization source category. The results of this analyiss will assist EPA in determining whether a residual risk rule for this source category is appropriate.

  20. Fasting, but Not Aging, Dramatically Alters the Redox Status of Cysteine Residues on Proteins in Drosophila melanogaster.

    PubMed

    Menger, Katja E; James, Andrew M; Cochemé, Helena M; Harbour, Michael E; Chouchani, Edward T; Ding, Shujing; Fearnley, Ian M; Partridge, Linda; Murphy, Michael P

    2015-06-30

    Altering the redox state of cysteine residues on protein surfaces is an important response to environmental challenges. Although aging and fasting alter many redox processes, the role of cysteine residues is uncertain. To address this, we used a redox proteomic technique, oxidative isotope-coded affinity tags (OxICAT), to assess cysteine-residue redox changes in Drosophila melanogaster during aging and fasting. This approach enabled us to simultaneously identify and quantify the redox state of several hundred cysteine residues in vivo. Cysteine residues within young flies had a bimodal distribution with peaks at ∼10% and ∼85% reversibly oxidized. Surprisingly, these cysteine residues did not become more oxidized with age. In contrast, 24 hr of fasting dramatically oxidized cysteine residues that were reduced under fed conditions while also reducing cysteine residues that were initially oxidized. We conclude that fasting, but not aging, dramatically alters cysteine-residue redox status in D. melanogaster.

  1. OECD Maximum Residue Limit Calculator

    EPA Pesticide Factsheets

    With the goal of harmonizing the calculation of maximum residue limits (MRLs) across the Organisation for Economic Cooperation and Development, the OECD has developed an MRL Calculator. View the calculator.

  2. Demonstration of catalytic combustion with residual fuel

    NASA Technical Reports Server (NTRS)

    Dodds, W. J.; Ekstedt, E. E.

    1981-01-01

    An experimental program was conducted to demonstrate catalytic combustion of a residual fuel oil. Three catalytic reactors, including a baseline configuration and two backup configurations based on baseline test results, were operated on No. 6 fuel oil. All reactors were multielement configurations consisting of ceramic honeycomb catalyzed with palladium on stabilized alumina. Stable operation on residual oil was demonstrated with the baseline configuration at a reactor inlet temperature of about 825 K (1025 F). At low inlet temperature, operation was precluded by apparent plugging of the catalytic reactor with residual oil. Reduced plugging tendency was demonstrated in the backup reactors by increasing the size of the catalyst channels at the reactor inlet, but plugging still occurred at inlet temperature below 725 K (845 F). Operation at the original design inlet temperature of 589 K (600 F) could not be demonstrated. Combustion efficiency above 99.5% was obtained with less than 5% reactor pressure drop. Thermally formed NO sub x levels were very low (less than 0.5 g NO2/kg fuel) but nearly 100% conversion of fuel-bound nitrogen to NO sub x was observed.

  3. Americium recovery from reduction residues

    DOEpatents

    Conner, W.V.; Proctor, S.G.

    1973-12-25

    A process for separation and recovery of americium values from container or bomb'' reduction residues comprising dissolving the residues in a suitable acid, adjusting the hydrogen ion concentration to a desired level by adding a base, precipitating the americium as americium oxalate by adding oxalic acid, digesting the solution, separating the precipitate, and thereafter calcining the americium oxalate precipitate to form americium oxide. (Official Gazette)

  4. Effect of household processing on fenazaquin residues in okra fruits.

    PubMed

    Duhan, Anil; Kumari, Beena; Gulati, Rachna

    2010-02-01

    Fenazaquin (4-[[4 (1,1-dimethylethyl) phenyl] ethoxy]quinazoline) is a new acaricide of the quinazoline class. Residue levels of fenazaquin were determined in unprocessed and processed okra fruits to evaluate the effect of different processes (washing, boiling and washing followed by boiling) in reduction of residues of this pesticide in okra. The study was carried out on okra crop (Variety, Varsha Uphar) in research farm of Chaudhary Charan Singh Haryana Agricultural University, Hisar with application of fenazaquin (Magister 10 EC) @ 125 ga.i./ha (Single Dose, T(1)) and 250 g a.i./ha (Double Dose, T(2)). Samples of okra fruits were collected on 0, 3, 7, 15 days after treatment and at harvest (30 days). Residues were estimated by gas chromatograph equipped with capillary column and nitrogen phosphorus detector. Residues reached below maximum residue limit of 0.01 mg/kg at harvest. The residues dissipated with half-life period of 3.13 days at lower dose and 4.43 days at higher dose. Processing is shown to be very effective in reducing the levels of fenazaquin residues in okra fruits. Maximum reduction (60-61%) was observed by washing + boiling followed by boiling/cooking (38-40%) and then by washing (31-32%).

  5. Temporary stabilization of air pollution control residues using carbonation.

    PubMed

    Zhang, Hua; He, Pin-Jing; Shao, Li-Ming; Lee, Duu-Jong

    2008-01-01

    Carbonation presents a good prospect for stabilizing alkaline waste materials. The risk of metal leaching from carbonated waste was investigated in the present study; in particular, the effect of the carbonation process and leachate pH on the leaching toxicity of the alkaline air pollution control (APC) residues from municipal solid waste incinerator was evaluated. The pH varying test was conducted to characterize the leaching characteristics of the raw and carbonated residue over a broad range of pH. Partial least square modeling and thermodynamic modeling using Visual MINTEQ were applied to highlight the significant process parameters that controlled metal leaching from the carbonated residue. By lowering the pH to 8-11, the carbonation process reduced markedly the leaching toxicity of the alkaline APC residue; however, the treated APC residue showed similar potential risk of heavy metal release as the raw ash when subjected to an acid shock. The carbonated waste could, thereby, not be disposed of safely. Nonetheless, carbonation could be applied as a temporary stabilization process for heavy metals in APC residues in order to reduce the leaching risk during its transportation and storage before final disposal.

  6. Sugar composition of the pectic polysaccharides of charophytes, the closest algal relatives of land-plants: presence of 3-O-methyl-d-galactose residues

    PubMed Central

    O’Rourke, Christina; Gregson, Timothy; Murray, Lorna; Sadler, Ian H.; Fry, Stephen C.

    2015-01-01

    Background and Aims During evolution, plants have acquired and/or lost diverse sugar residues as cell-wall constituents. Of particular interest are primordial cell-wall features that existed, and in some cases abruptly changed, during the momentous step whereby land-plants arose from charophytic algal ancestors. Methods Polysaccharides were extracted from four charophyte orders [Chlorokybales (Chlorokybus atmophyticus), Klebsormidiales (Klebsormidium fluitans, K. subtile), Charales (Chara vulgaris, Nitella flexilis), Coleochaetales (Coleochaete scutata)] and an early-diverging land-plant (Anthoceros agrestis). ‘Pectins’ and ‘hemicelluloses’, operationally defined as extractable in oxalate (100 °C) and 6 m NaOH (37 °C), respectively, were acid- or Driselase-hydrolysed, and the monosaccharides analysed chromatographically. One unusual monosaccharide, ‘U’, was characterized by 1H/13C-nuclear magnetic resonance spectroscopy and also enzymically. Key Results ‘U’ was identified as 3-O-methyl-d-galactose (3-MeGal). All pectins, except in Klebsormidium, contained acid- and Driselase-releasable galacturonate, suggesting homogalacturonan. All pectins, without exception, released rhamnose and galactose on acid hydrolysis; however, only in ‘higher’ charophytes (Charales, Coleochaetales) and Anthoceros were these sugars also efficiently released by Driselase, suggesting rhamnogalacturonan-I. Pectins of ‘higher’ charophytes, especially Chara, contained little arabinose, instead possessing 3-MeGal. Anthoceros hemicelluloses were rich in glucose, xylose, galactose and arabinose (suggesting xyloglucan and arabinoxylan), none of which was consistently present in charophyte hemicelluloses. Conclusions Homogalacturonan is an ancient streptophyte feature, albeit secondarily lost in Klebsormidium. When conquering the land, the first embryophytes already possessed rhamnogalacturonan-I. In contrast, charophyte and land-plant hemicelluloses differ

  7. Residual stresses and their effects in composite laminates

    NASA Technical Reports Server (NTRS)

    Hahn, H. T.; Hwang, D. G.

    1983-01-01

    Residual stresses in composite laminates are caused by the anisotropy in expansional properties of constituent unidirectional plies. The effect of these residual stresses on dimensional stability is studied through the warping of unsymmetric (0 sub 4/90 sub 4)sub T graphite/epoxy laminates while their effect on ply failure is analyzed for (0/90)sub 2s Kevlar 49/epoxy laminate. The classical laminated plate theory is used to predict the warping of small and large panels. The change of warping does not indicate a noticeable stress relaxation at 75 C while it is very sensitive to moisture content and hence to environment. A prolonged gellation at the initial cure temperature reduces residual stresses while postcure does not. The matrix/interface cracking in dry (0/90)sub 2s Kevlar 49/epoxy laminate is shown to be the result of the residual stress exceeding the transverse strength.

  8. Residual stress measurements of tension leg platform tendon welds

    SciTech Connect

    Kim, D.S.; Smith, J.D.

    1994-12-31

    Results of fatigue test of prototype welded tendons showed that fatigue life was greatly reduced for the weld repaired joint. Since tensile residual stresses near the fusion boundary were suspected to cause the fatigue life reduction, these residual stresses were measured. Residual stresses of girth welded tendon pipes for a tension leg platform (TLP) were obtained for various fabrication conditions. The stresses were measured experimentally using the blind hole drilling (BHD) technique, X-ray diffraction (XRD) technique and Barkhausen Noise (BHN) method. The results of these measurements illustrate the reliability of each measurement technique. Effects of joint configuration, weld repair, weld cap grinding, and pre-fatigue test on residual stresses were discussed.

  9. Residual Resistance Data from Cavity Production Projects at Jefferson Lab

    SciTech Connect

    Gianluigi Ciovati, Rongli Geng, John Mammosser, Jeffrey Saunders

    2010-11-01

    A fundamental limitation towards achieving high quality factors in superconducting radio-frequency cavities is the so-called residual resistance. Understanding and controlling the residual resistance has important implications towards improving the efficiency and reduce the operating cost of continuous wave superconducting linear accelerators. In this contribution we will report on the residual resistance values obtained from measurements of the quality factor of a large set of cavities, with resonant frequency between 805 MHz and 1.5 GHz, all of them processed and tested at Jefferson Lab. Surface treatments included both buffered chemical polishing and electropolishing. The results indicate an approximate value of the residual resistance of about 7-10 n Omega.

  10. DISSOLUTION OF NEPTUNIUM OXIDE RESIDUES

    SciTech Connect

    Kyser, E

    2009-01-12

    This report describes the development of a dissolution flowsheet for neptunium (Np) oxide (NpO{sub 2}) residues (i.e., various NpO{sub 2} sources, HB-Line glovebox sweepings, and Savannah River National Laboratory (SRNL) thermogravimetric analysis samples). Samples of each type of materials proposed for processing were dissolved in a closed laboratory apparatus and the rate and total quantity of off-gas were measured. Samples of the off-gas were also analyzed. The quantity and type of solids remaining (when visible) were determined after post-dissolution filtration of the solution. Recommended conditions for dissolution of the NpO{sub 2} residues are: Solution Matrix and Loading: {approx}50 g Np/L (750 g Np in 15 L of dissolver solution), using 8 M nitric acid (HNO{sub 3}), 0.025 M potassium fluoride (KF) at greater than 100 C for at least 3 hours. Off-gas: Analysis of the off-gas indicated nitric oxide (NO), nitrogen dioxide (NO{sub 2}) and nitrous oxide (N{sub 2}O) as the only identified components. No hydrogen (H{sub 2}) was detected. The molar ratio of off-gas produced per mole of Np dissolved ranged from 0.25 to 0.4 moles of gas per mole of Np dissolved. A peak off-gas rate of {approx}0.1 scfm/kg bulk oxide was observed. Residual Solids: Pure NpO{sub 2} dissolved with little or no residue with the proposed flowsheet but the NpCo and both sweepings samples left visible solid residue after dissolution. For the NpCo and Part II Sweepings samples the residue amounted to {approx}1% of the initial material, but for the Part I Sweepings sample, the residue amounted to {approx}8 % of the initial material. These residues contained primarily aluminum (Al) and silicon (Si) compounds that did not completely dissolve under the flowsheet conditions. The residues from both sweepings samples contained minor amounts of plutonium (Pu) particles. Overall, the undissolved Np and Pu particles in the residues were a very small fraction of the total solids.

  11. Evaluation of residue-residue contact prediction in CASP10

    PubMed Central

    Monastyrskyy, Bohdan; D’Andrea, Daniel; Fidelis, Krzysztof; Tramontano, Anna; Kryshtafovych, Andriy

    2013-01-01

    We present the results of the assessment of the intra-molecular residue-residue contact predictions from 26 prediction groups participating in the 10th round of the CASP experiment. The most recently developed direct coupling analysis methods did not take part in the experiment likely because they require a very deep sequence alignment not available for any of the 114 CASP10 targets. The performance of contact prediction methods was evaluated with the measures used in previous CASPs (i.e., prediction accuracy and the difference between the distribution of the predicted contacts and that of all pairs of residues in the target protein), as well as new measures, such as the Matthews correlation coefficient, the area under the precision-recall curve and the ranks of the first correctly and incorrectly predicted contact. We also evaluated the ability to detect inter-domain contacts and tested whether the difficulty of predicting contacts depends upon the protein length and the depth of the family sequence alignment. The analyses were carried out on the target domains for which structural homologs did not exist or were difficult to identify. The evaluation was performed for all types of contacts (short, medium, and long-range), with emphasis placed on long-range contacts, i.e. those involving residues separated by at least 24 residues along the sequence. The assessment suggests that the best CASP10 contact prediction methods perform at approximately the same level, and comparably to those participating in CASP9. PMID:23760879

  12. Residual stresses in welded plates

    NASA Technical Reports Server (NTRS)

    Bernstein, Edward L.

    1994-01-01

    The purpose of this project was to develop a simple model which could be used to study residual stress. The mechanism that results in residual stresses in the welding process starts with the deposition of molten weld metal which heats the immediately adjacent material. After solidification of weld material, normal thermal shrinkage is resisted by the adjacent, cooler material. When the thermal strain exceeds the elastic strain corresponding to the yield point stress, the stress level is limited by this value, which decreases with increasing temperature. Cooling then causes elastic unloading which is restrained by the adjoining material. Permanent plastic strain occurs, and tension is caused in the region immediately adjacent to the weld material. Compression arises in the metal farther from the weld in order to maintain overall static equilibrium. Subsequent repair welds may add to the level of residual stresses. The level of residual stress is related to the onset of fracture during welding. Thus, it is of great importance to be able to predict the level of residual stresses remaining after a weld procedure, and to determine the factors, such as weld speed, temperature, direction, and number of passes, which may affect the magnitude of remaining residual stress. It was hoped to use traditional analytical modeling techniques so that it would be easier to comprehend the effect of these variables on the resulting stress. This approach was chosen in place of finite element methods so as to facilitate the understanding of the physical processes. The accuracy of the results was checked with some existing experimental studies giving residual stress levels found from x-ray diffraction measurements.

  13. Hydrothermal carbonization of agricultural residues.

    PubMed

    Oliveira, Ivo; Blöhse, Dennis; Ramke, Hans-Günter

    2013-08-01

    The work presented in this article addresses the application of hydrothermal carbonization (HTC) to produce a solid fuel named HTC-Biochar, whose characteristics are comparable to brown coal. Several batch HTC experiments were performed using agricultural residues (AR) as substrates, commonly treated in farm-based biogas plants in Germany. Different AR were used in different combinations with other biomass residues. The biogas potential from the resulting process water was also determined. The combination of different AR lead to the production of different qualities of HTC-Biochars as well as different mass and energy yields. Using more lignocellulosic residues lead to higher mass and energy yields for the HTC-Biochar produced. Whilst residues rich in carbohydrates of lower molecular weight such as corn silage and dough residues lead to the production of a HTC-Biochar of better quality and more similar to brown coal. Process water achieved a maximum of 16.3 L CH4/kg FM (fresh matter).

  14. [Effect of corrosion inhibitor on the producing of exopolymer complex by sulphate-reducing bacteria].

    PubMed

    Purish, L M; Asaulenko, L H; Kozlova, I P

    2007-01-01

    It is established that the specific productivity of exopolymer complex (EPM) synthesized by the cells of sulphate-reducing bacteria in a biofilm was 1.5 times higher than in plankton. A sharp increase of the specific productivity of EPM in the biofilm is observed when corrosion inhibitor is introduced in the environment. The inhibitor concentration being 1.0 g/l, the biofilm cells produced almost 18 times more of EPM than the bacteria cells in plankton. It is shown that the film exopolymers include glucose, galactose, mannose, xylose, ribose and three nondetermined sugars, while plankton cells also include rhamnose. Rhamnose appeared in the biofilm EPM composition and rhamnose, arabinose and fucose appeared in EPM of plankton cells as affected by the inhibitor. A necessity of investigating the biofilm formation for developing the methods of anticorrosive protection is discussed.

  15. Recycling crop residues for use in recirculating hydroponic crop production

    NASA Technical Reports Server (NTRS)

    Mackowiak, C. L.; Garland, J. L.; Sager, J. C.

    1996-01-01

    As part of bioregenerative life support feasibility testing by NASA, crop residues are being used to resupply elemental nutrients to recirculating hydroponic crop production systems. Methods for recovering nutrients from crop residues have evolved from water soaking (leaching) to rapid aerobic bioreactor processing. Leaching residues recovered the majority of elements but it also recovered significant amounts of soluble organics. The high organic content of leachates was detrimental to plant growth. Aerobic bioreactor processing reduced the organic content ten-fold, which reduced or eliminated phytotoxic effects. Wheat and potato production studies were successful using effluents from reactors having with 8- to 1-day retention times. Aerobic bioreactor effluents supplied at least half of the crops elemental mass needs in these studies. Descriptions of leachate and effluent mineral content, biomass productivity, microbial activity, and nutrient budgets for potato and wheat are presented.

  16. Dry fermentation of agricultural residues

    NASA Astrophysics Data System (ADS)

    Jewell, W. J.; Chandler, J. A.; Dellorto, S.; Fanfoni, K. J.; Fast, S.; Jackson, D.; Kabrick, R. M.

    1981-09-01

    A dry fermentation process is discussed which converts agricultural residues to methane, using the residues in their as produced state. The process appears to simplify and enhance the possibilities for using crop residues as an energy source. The major process variables investigated include temperature, the amount and type of inoculum, buffer requirements, compaction, and pretreatment to control the initial available organic components that create pH problems. A pilot-scale reactor operation on corn stover at a temperature of 550 C, with 25 percent initial total solids, a seed-to-feed ratio of 2.5 percent, and a buffer-to-feed ratio of 8 percent achieved 33 percent total volatile solids destruction in 60 days. Volumetric biogas yields from this unit were greater than 1 vol/vol day for 12 days, and greater than 0.5 vol/vol day for 32 days, at a substrate density of 169 kg/m (3).

  17. Enhanced enzyme activities of inclusion bodies of recombinant beta-galactosidase via the addition of inducer analog after L-arabinose induction in the araBAD promoter system of Escherichia coli.

    PubMed

    Jung, Kyung-Hwan

    2008-03-01

    We observed that an inclusion body (IB) of recombinant beta-galactosidase that was produced by the araBAD promoter system in Escherichia coli (E. coli) showed enzyme activity. In order to improve its activity, the lowering of the transcription rate of the beta-galactosidase structural gene was attempted through competition between an inducer (L-arabinose) and an inducer analog (D-fucose). In the deep-well microtiter plate culture and lab-scale fermentor culture, it was demonstrated that the addition of D-fucose caused an improvement in specific beta-galactosidase production, although beta-galactosidase was produced as an IB. In particular, the addition of D-fucose after induction led to an increase in the specific activity of beta-galactosidase IB. Finally, we confirmed that the addition of D-fucose after induction caused changes in the structure of beta-galactosidase IB, with higher enzyme activity. Based on these results, we expect that an improved enzyme IB will be used as a biocatalyst of the enzyme bioprocess, because an enzyme IB can be purified easily and has physical durability.

  18. Genetic Interaction of Aspergillus nidulans galR, xlnR and araR in Regulating D-Galactose and L-Arabinose Release and Catabolism Gene Expression.

    PubMed

    Kowalczyk, Joanna E; Gruben, Birgit S; Battaglia, Evy; Wiebenga, Ad; Majoor, Eline; de Vries, Ronald P

    2015-01-01

    In Aspergillus nidulans, the xylanolytic regulator XlnR and the arabinanolytic regulator AraR co-regulate pentose catabolism. In nature, the pentose sugars D-xylose and L-arabinose are both main building blocks of the polysaccharide arabinoxylan. In pectin and arabinogalactan, these two monosaccharides are found in combination with D-galactose. GalR, the regulator that responds to the presence of D-galactose, regulates the D-galactose catabolic pathway. In this study we investigated the possible interaction between XlnR, AraR and GalR in pentose and/or D-galactose catabolism in A. nidulans. Growth phenotypes and metabolic gene expression profiles were studied in single, double and triple disruptant A. nidulans strains of the genes encoding these paralogous transcription factors. Our results demonstrate that AraR and XlnR not only control pentose catabolic pathway genes, but also genes of the oxido-reductive D-galactose catabolic pathway. This suggests an interaction between three transcriptional regulators in D-galactose catabolism. Conversely, GalR is not involved in regulation of pentose catabolism, but controls only genes of the oxido-reductive D-galactose catabolic pathway.

  19. l-Arabinose Isomerase and d-Xylose Isomerase from Lactobacillus reuteri: Characterization, Coexpression in the Food Grade Host Lactobacillus plantarum, and Application in the Conversion of d-Galactose and d-Glucose

    PubMed Central

    2014-01-01

    The l-arabinose isomerase (l-AI) and the d-xylose isomerase (d-XI) encoding genes from Lactobacillus reuteri (DSMZ 17509) were cloned and overexpressed in Escherichia coli BL21 (DE3). The proteins were purified to homogeneity by one-step affinity chromatography and characterized biochemically. l-AI displayed maximum activity at 65 °C and pH 6.0, whereas d-XI showed maximum activity at 65 °C and pH 5.0. Both enzymes require divalent metal ions. The genes were also ligated into the inducible lactobacillal expression vectors pSIP409 and pSIP609, the latter containing a food grade auxotrophy marker instead of an antibiotic resistance marker, and the l-AI- and d-XI-encoding sequences/genes were coexpressed in the food grade host Lactobacillus plantarum. The recombinant enzymes were tested for applications in carbohydrate conversion reactions of industrial relevance. The purified l-AI converted d-galactose to d-tagatose with a maximum conversion rate of 35%, and the d-XI isomerized d-glucose to d-fructose with a maximum conversion rate of 48% at 60 °C. PMID:24443973

  20. Chemistry of combined residual chlorination

    SciTech Connect

    Leao, S.F.; Selleck, R.E.

    1982-01-01

    The decay of the combined chlorine residual was investigated in this work. Recent concerns about the formation of undesirable compounds such as chloroform with free residual chlorination have focused attention on the alternative use of combined residual chlorination. This work investigates the applicability of reactions proposed to describe the transformations and decay of the combined residual with time. Sodium hypochlorite was added to buffered solutions of ammonia with the chlorine residual being monitored over periods extending up to 10 days. The reaction was studied at four initial concentrations of hypochlorite of 100, 50, 25 and 10 mg/L as Cl/sub 2/ with molar application ratios of chlorine to ammonia, defined herein as M ratios, of 0.90, 0.50, 0.25 and 0.05 at each hypochlorite dose. Sixty-eight experiments were conducted at the pH of 6.6 and 7.2. The conclusions are: (1) in the absence of free chlorine, the concentration of NH/sub 3/ does not seem to affect the rate of disappearance of the residual other than through the formation of NHCl/sub 2/ by NH/sub 2/Cl hydrolysis; (2) the reaction between NHCl/sub 2/ and NH/sub 4//sup +/ to form NH/sub 2/Cl is either much slower than reported by Gray et. al. or the mechanism is different with a rate limiting step not involving NH/sub 3/ or NH/sub 4//sup +/; (3) a redox reaction in addition to the first-order decomposition of NHCl/sub 2/ appears necessary. Model simulation results indicated that a reaction of the type NH/sub 2/Cl + NHCl/sub 2/ ..-->.. P added to the first-order NHCl/sub 2/ decomposition can explain the results observed except at the higher chlorine doses.

  1. Residual contact restraints in cryogenics

    NASA Astrophysics Data System (ADS)

    Cretegny, J. F.; Demonicault, J. M.

    The use of residual stress measurements to evaluate the state of cryogenic turbomachines, whose surfaces are worn by the working conductions in dry contact, is addressed. Their contribution to the understanding of the reasons of possible ruptures is considered. It is stated that residual stress measurements should be used as a complementary tool rather than as input data for models. It is shown, thanks to two examples concerning the ball bearings and splines of the liquid hydrogen turbopump of the Vulcain engine, what can be expected from such techniques. Total exploitation of the results has still to be done, but preliminary results are quite encouraging.

  2. Pesticide residues in olive oil.

    PubMed

    Lentza-Rizos, C; Avramides, E J

    1995-01-01

    The attacks of pests and diseases and the presence of weeds make it necessary to apply pesticides to olive trees to ensure crop protection. Residues of these compounds may remain and contaminate the oil produced. For the analysis of pesticide residues in olive oil, the most common methods are multiresidue methods for fatty substrates, based on partitioning between hexane or light petroleum and acetonitrile. Recently, other methods have been applied, such as ready-to-use, disposable minicolumns or direct injection of oil into a capillary gas chromatograph equipped with a precolumn with an oil recovery tank. Although several pesticides are registered in oil-producing countries for use on olive trees, available literature on the level and fate of residues is very limited. However, it is clear that fat-soluble pesticides tend to concentrate in the oil, both after full coverage and bait spraying, and their use close to harvest should therefore be avoided. Because it is sometimes necessary to use such pesticides late in autumn because of their effectiveness in cases of severe attack, residue trials should be carried out to determine the residue concentration in oil and to set a reasonable preharvest safety interval. Data produced by such trials would permit the establishment of MRLs (tolerances) in olive oil to cover cases where the residues, although relatively high, are not of toxicological significance for consumers (risk assessment). Such is the case with corn oil and the fat-soluble insecticide methyl pirimiphos, registered in the U.S. for use on corn. The U.S. EPA tolerance for methyl pirimiphos in corn is 8 mg/kg, whereas it is 11 times higher (88 mg/kg) for corn oil because it is known to concentrate in the oil. Similar provisions for olive oil, based on data from residue trials according to Good Agricultural Practice, the long-term toxicity of each pesticide as expressed by its ADI for man, and olive oil consumption patterns, would facilitate international trade

  3. Total radioactive residues and residues of [36Cl]chlorate in market size broilers.

    PubMed

    Smith, David J; Byrd, James A; Anderson, Robin C

    2007-07-11

    The oral administration of chlorate salts reduces the numbers of Gram-negative pathogens in gastrointestinal tracts of live food animals. Although the efficacy of chlorate salts has been demonstrated repeatedly, the technology cannot be introduced into commercial settings without first demonstrating that chlorate residues, and metabolites of chlorate remaining in edible tissues, represent a negligible risk to consumers. Typically, a first step in this risk assessment is to quantify the parent compound and to identify metabolites remaining in edible tissues of animals treated with the experimental compound. The objectives of this study were to determine the pathway(s) of chlorate metabolism in market broilers and to determine the magnitude of chlorate residues remaining in edible tissues. To this end, 12 broilers (6 weeks; 2.70+/-0.34 kg) were randomly assigned to three treatments of 7.4, 15.0, and 22.5 mM sodium [36Cl]chlorate dissolved in drinking water (n=4 broilers per treatment). Exposure to chlorate, dissolved in drinking water, occurred at 0 and 24 h (250 mL per exposure), feed was withdrawn at hour 38, water was removed at hour 48, and birds were slaughtered at hour 54 (16 h after feed removal and 8 h after water removal). The radioactivity was rapidly eliminated in excreta with 69-78% of the total administered radioactivity being excreted by slaughter. Total radioactive residues were proportional to dose in all edible tissues with chloride ion comprising greater than 98.5% of the radioactive residue for the tissue (9.4-97.8 ppm chlorate equivalents). Chlorate residues were typically greatest in the skin (0.33-0.82 ppm), gizzard (0.1-0.137 ppm), and dark muscle (0.05-0.14 ppm). Adipose, liver, and white muscle tissue contained chlorate concentrations from 0.03 to 0.13 ppm. In contrast, chlorate concentrations in excreta eliminated during the 6 h period prior to slaughter ranged from 53 to 71 ppm. Collectively, these data indicate that broilers rapidly

  4. Collection of sugarcane crop residue for energy

    SciTech Connect

    Eiland, B.R.; Clayton, J.E.

    1982-12-01

    Crop residue left after sugarcane harvesting was recovered using a forage harvester and a large round baler. The quantity, bulk density and moisture content of the crop residue was determined in four fields. Crop residue from 7 ha was burned in boilers at a sugar mill. Samples of this residue were tested by a laboratory and compared to sugarcane bagasse.

  5. CHARACTERIZING PESTICIDE RESIDUE TRANSFER EFFICIENCIES USING FLUORESCENT TRACER IMAGING TECHNIQUES

    EPA Science Inventory

    To reduce the uncertainty associated with current estimates of children's exposure to pesticides by dermal contact and non-dietary ingestion, residue transfer data are required. Prior to conducting exhaustive studies, a screening study was conducted to identify the important pa...

  6. Compounding of ultrasound B-scans of a transfemoral residual limb using a genetic algorithm

    NASA Astrophysics Data System (ADS)

    Douglas, Tania S.; Lee, Peter; Solomonidis, Stephan E.; Spence, William D.

    1998-06-01

    Ultrasound may be used for imaging the trans-femoral residual limb in order to provide information for the improvement of prosthetic socket design. Compounding of several ultrasound B-scans is required for obtaining transverse images of the residual limb. In this paper, a method is presented by which a genetic algorithm is used to match B-scans taken in a horizontal plane around the residual limb for image compounding in order to reduce the effects of patient motion during scanning.

  7. Potential hazards of fumigant residues.

    PubMed Central

    Fishbein, L

    1976-01-01

    A spectrum of fumigants (primarily ethylene dibromide, 1,2-dibromo-3-chloropropane, ethylene oxide, symdibromotetetrachloroethane, 1,3-dichloropropene, dichlorovos, carbon tetrachloride, methyl bromide) as well as their degradation products in foodstuffs and soil have been examined mainly in regard to the potential mutagenicity of their residues. PMID:789068

  8. Residual Stresses in Ground Steels.

    DTIC Science & Technology

    1979-06-13

    stress near the surface can be lower. The level of residual stress is also strongly affected by carbon,’3 which influences the microplastic behaviour of...1966, Vol. 14, 99-104. 14. C. 3. )4cMahon: “ Microplastic Behaviour in Iron” in Mv. in Mater . S d . Res., Vol. 2, 121-140, Interscience, New York

  9. Implication of Terminal Residues at Protein-Protein and Protein-DNA Interfaces.

    PubMed

    Martin, Olivier M F; Etheve, Loïc; Launay, Guillaume; Martin, Juliette

    2016-01-01

    Terminal residues of protein chains are charged and more flexible than other residues since they are constrained only on one side. Do they play a particular role in protein-protein and protein-DNA interfaces? To answer this question, we considered large sets of non-redundant protein-protein and protein-DNA complexes and analyzed the status of terminal residues and their involvement in interfaces. In protein-protein complexes, we found that more than half of terminal residues (62%) are either modified by attachment of a tag peptide (10%) or have missing coordinates in the analyzed structures (52%). Terminal residues are almost exclusively located at the surface of proteins (94%). Contrary to charged residues, they are not over or under-represented in protein-protein interfaces, but strongly prefer the peripheral region of interfaces when present at the interface (83% of terminal residues). The almost exclusive location of terminal residues at the surface of the proteins or in the rim regions of interfaces explains that experimental methods relying on tail hybridization can be successfully applied without disrupting the complexes under study. Concerning conformational rearrangement in protein-protein complexes, despite their expected flexibility, terminal residues adopt similar locations between the free and bound forms of the docking benchmark. In protein-DNA complexes, N-terminal residues are twice more frequent than C-terminal residues at interfaces. Both N-terminal and C-terminal residues are under-represented in interfaces, in contrast to positively charged residues, which are strongly favored. When located in protein-DNA interfaces, terminal residues prefer the periphery. N-terminal and C-terminal residues thus have particular properties with regard to interfaces, which cannot be reduced to their charged nature.

  10. Alcohol production from agricultural and forestry residues

    SciTech Connect

    Dale, L; Opilla, R; Surles, T

    1980-09-01

    Technologies available for the production of ethanol from whole corn are reviewed. Particular emphasis is placed on the environmental aspects of the process, including land utilization and possible air and water pollutants. Suggestions are made for technological changes intended to improve the economics of the process as well as to reduce some of the pollution from by-product disposal. Ethanol may be derived from renewable cellulosic substances by either enzymatic or acid hydrolysis of cellulose to sugar, followed by conventional fermentation and distillation. The use of two agricultural residues - corn stover (field stalks remaining after harvest) and straw from wheat crops - is reviewed as a cellulosic feedstock. Two processes have been evaluated with regard to environmental impact - a two-stage acid process developed by G.T. Tsao of Purdue University and an enzymatic process based on the laboratory findings of C.R. Wilke of the University of California, Berkeley. The environmental residuals expected from the manufacture of methyl and ethyl alcohols from woody biomass are covered. The methanol is produced in a gasification process, whereas ethanol is produced by hydrolysis and fermentation processes similar to those used to derive ethanol from cellulosic materials.

  11. Alcohol production from agricultural and forestry residues

    SciTech Connect

    Opilla, R.; Dale, L.; Surles, T.

    1980-05-01

    A variety of carbohydrate sources can be used as raw material for the production of ethanol. Section 1 is a review of technologies available for the production of ethanol from whole corn. Particular emphasis is placed on the environmental aspects of the process, including land utilization and possible air and water pollutants. Suggestions are made for technological changes intended to improve the economics of the process as well as to reduce some of the pollution from by-product disposal. Ethanol may be derived from renewable cellulosic substances by either enzymatic or acid hydrolysis of cellulose to sugar, followed by conventional fermentation and distillation. Section 2 is a review of the use of two agricultural residues - corn stover (field stalks remaining after harvest) and straw from wheat crops - as a cellulosic feedstock. Two processes have been evaluated with regard to environmental impact - a two-stage acid process developed by G.T. Tsao of Purdue University and an enzymatic process based on the laboratory findings of C.R. Wilke of the University of California, Berkeley. Section 3 deals with the environmental residuals expected from the manufacture of methyl and ethyl alcohols from woody biomass. The methanol is produced in a gasification process, whereas ethanol is produced by hydrolysis and fermentation processes similar to those used to derive ethanol from cellulosic materials.

  12. Carbonation of residual brines produced by ammonia-soda process

    NASA Astrophysics Data System (ADS)

    Filippova, I. V.; Piriou, P.; Filippov, L. O.; Yvon, J.; Grandjean, M.

    2013-03-01

    This work deals with the carbonation of residual brines produced during the manufacture of soda ash to avoid the unsuitable phase transformation during the land storage. The study resulted in a demonstration pilot, which showed the feasibility of such an approach and the possibility of his extension to an industrial scale. Carbonation of the residual brines is a promising process as it entirely transforms Ca(OH)2, "CaOHCl" and CSH into calcite, avoids the further phase evolution, allows to obtain a neutral pH which considerably reduce the land storage impact on environment and shorten by around 10 % the global CO2 emission of the ammonia-soda process.

  13. Performance of Container-Grown Loropetalum Grown in Clean Chip Residual Substrate

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The idea of using forest residuals is gaining in popularity as a replacement for pine bark (PB) in nursery crop substrates due to reduced availability of PB. Clean Chip Residual (CCR) is a by-product of in-field forestry harvesting practices. This material, composed of roughly 50% wood, 40% bark, an...

  14. Pesticidal residues in animal tissues

    USGS Publications Warehouse

    DeWitt, J.B.; Menzie, C.M.; Adomaitis, V.A.; Reichel, W.L.

    1960-01-01

    Tests with penned starlings, rats, pheasants, and ducks indicated that each species differs in sensitivity to the various pesticides. Residues in tissues are proportional to the degree of exposure during area treatment and they are also found in animals shot six or more months after treatment. The presence of more than 20-30 ppm of DDT, 20 ppm of chlordan, and 6-20 ppm of heptachlor epoxide in quail tissues indicated that the birds had ingested lethal dosages of the pesticides.

  15. Calcination/dissolution residue treatment

    SciTech Connect

    Knight, R.C.; Creed, R.F.; Patello, G.K.; Hollenberg, G.W.; Buehler, M.F.; O`Rourke, S.M.; Visnapuu, A.; McLaughlin, D.F.

    1994-09-01

    Currently, high-level wastes are stored underground in steel-lined tanks at the Hanford site. Current plans call for the chemical pretreatment of these wastes before their immobilization in stable glass waste forms. One candidate pretreatment approach, calcination/dissolution, performs an alkaline fusion of the waste and creates a high-level/low-level partition based on the aqueous solubilities of the components of the product calcine. Literature and laboratory studies were conducted with the goal of finding a residue treatment technology that would decrease the quantity of high-level waste glass required following calcination/dissolution waste processing. Four elements, Fe, Ni, Bi, and U, postulated to be present in the high-level residue fraction were identified as being key to the quantity of high-level glass formed. Laboratory tests of the candidate technologies with simulant high-level residues showed reductive roasting followed by carbonyl volatilization to be successful in removing Fe, Ni, and Bi. Subsequent bench-scale tests on residues from calcination/dissolution processing of genuine Hanford Site tank waste showed Fe was separated with radioelement decontamination factors of 70 to 1,000 times with respect to total alpha activity. Thermodynamic analyses of the calcination of five typical Hanford Site tank waste compositions also were performed. The analyses showed sodium hydroxide to be the sole molten component in the waste calcine and emphasized the requirement for waste blending if fluid calcines are to be achieved. Other calcine phases identified in the thermodynamic analysis indicate the significant thermal reconstitution accomplished in calcination.

  16. Electromechanical Apparatus Measures Residual Stress

    NASA Technical Reports Server (NTRS)

    Chern, Engmin J.; Flom, Yury

    1993-01-01

    Nondestructive test exploits relationship between stress and eddy-current-probe resistance. Yields data on residual stress or strain in metal tension/compression specimen (stress or strain remaining in specimen when no stress applied from without). Apparatus is assembly of commercial equipment: tension-or-compression testing machine, eddy-current probe, impedance gain-and-phase analyzer measuring impedance of probe coil, and desktop computer, which controls other equipment and processes data received from impedance gain-and-phase analyzer.

  17. Geotechnical characteristics of residual soils

    SciTech Connect

    Townsend, F.C.

    1985-01-01

    Residual soils are products of chemical weathering and thus their characteristics are dependent upon environmental factors of climate, parent material, topography and drainage, and age. These conditions are optimized in the tropics where well-drained regions produce reddish lateritic soils rich in iron and aluminum sesquioxides and kaolinitic clays. Conversely, poorly drained areas tend towards montmorillonitic expansive black clays. Andosols develop over volcanic ash and rock regions and are rich in allophane (amorphous silica) and metastable halloysite. The geological origins greatly affect the resulting engineering characteristics. Both lateritic soils and andosols are susceptible to property changes upon drying, and exhibit compaction and strength properties not indicative of their classification limits. Both soils have been used successfully in earth dam construction, but attention must be given to seepage control through the weathered rock. Conversely, black soils are unpopular for embankments. Lateritic soils respond to cement stabilization and, in some cases, lime stabilization. Andosols should also respond to lime treatment and cement treatments if proper mixing can be achieved. Black expansive residual soils respond to lime treatment by demonstrating strength gains and decreased expansiveness. Rainfall induced landslides are typical of residual soil deposits.

  18. Evaluation of residue drum storage safety risks

    SciTech Connect

    Conner, W.V.

    1994-06-17

    A study was conducted to determine if any potential safety problems exist in the residue drum backlog at the Rocky Flats Plant. Plutonium residues stored in 55-gallon drums were packaged for short-term storage until the residues could be processed for plutonium recovery. These residues have now been determined by the Department of Energy to be waste materials, and the residues will remain in storage until plans for disposal of the material can be developed. The packaging configurations which were safe for short-term storage may not be safe for long-term storage. Interviews with Rocky Flats personnel involved with packaging the residues reveal that more than one packaging configuration was used for some of the residues. A tabulation of packaging configurations was developed based on the information obtained from the interviews. A number of potential safety problems were identified during this study, including hydrogen generation from some residues and residue packaging materials, contamination containment loss, metal residue packaging container corrosion, and pyrophoric plutonium compound formation. Risk factors were developed for evaluating the risk potential of the various residue categories, and the residues in storage at Rocky Flats were ranked by risk potential. Preliminary drum head space gas sampling studies have demonstrated the potential for formation of flammable hydrogen-oxygen mixtures in some residue drums.

  19. Neutron scattering residual stress measurements on gray cast iron brake discs

    SciTech Connect

    Spooner, S.; Payzant, E.A.; Hubbard, C.R.

    1996-11-01

    Neutron diffraction was used to investigate the effects of a heat treatment designed to remove internal residual stresses in brake discs. It is believed that residual stresses may change the rate of deformation of the discs during severe braking conditions when the disc temperature is increased significantly. Neutron diffraction was used to map out residual strain distributions in a production disc before and after a stress-relieving heat treatment. Results from these neutron diffraction experiments show that some residual strains were reduced by as much as 400 microstrain by stress relieving. 5 refs., 5 figs., 1 tab.

  20. Residual flexibility test method for verification of constrained structural models

    NASA Technical Reports Server (NTRS)

    Admire, John R.; Tinker, Michael L.; Ivey, Edward W.

    1994-01-01

    A method is described for deriving constrained modes and frequencies from a reduced model based on a subset of the free-free modes plus the residual effects of neglected modes. The method involves a simple modification of the MacNeal and Rubin component mode representation to allow development of a verified constrained (fixed-base) structural model. Results for two spaceflight structures having translational boundary degrees of freedom show quick convergence of constrained modes using a measureable number of free-free modes plus the boundary partition of the residual flexibility matrix. This paper presents the free-free residual flexibility approach as an alternative test/analysis method when fixed-base testing proves impractical.

  1. Technique for the determination of asphaltenes in crude oil residues

    SciTech Connect

    Pearson, C.D.; Huff, G.S.; Gharfeh, S.G.

    1986-12-01

    Recently, the authors reported a method for the determination of saturates, aromatics, and resins in deasphaltened crude oil residues by high-performance liquid chromatography using a flame ionization detector. The present work describes a filtration technique for the determination of asphaltenes in crude oil residues using disposable Millex filters. This technique reduces the filtration, washing, and equilibration time needed for asphaltene determination. Six crude oil residues that varied widely in asphaltene content were used to evaluate the precision of this technique. The values obtained by Millex filters were compared to the values obtained by a conventional method using filter papers. Agreement between the two methods was very good. Several methods have been reported for the separation and determination of asphaltenes. Speight et al. made a survey of the different asphaltene procedures and conducted the experimental work to determine the optimum conditions for asphaltene separation and determination. The operating parameters recommended by Speight were used in this work.

  2. Speciation and recovery of chromium from chromite ore processing residues.

    PubMed

    Sreeram, K J; Ramasami, T

    2001-10-01

    The processing of chromite ore is associated with the generation of large quantities of solid wastes containing chromium, which have been disposed of as landfill for many years. The mobilization and operational speciation of chromium contained in soils contaminated with metal salts are important in terms of the environment. Several methods have been employed for the extraction and recovery of solid wastes. Chromium contained in contaminated soils and solid wastes can be categorized as exchangeable, oxidizable, carbonate-bound, reducible and residual. The results from this study indicate a need for efficient leaching methodologies in chromite ore processing plants to decrease the non-detrital fractions of chromium in the residue. Aggressive methodologies are required to recover chromium from the detrital fractions. The potential benefits of employing sodium peroxide for the complete recovery of chromium from chromite residue have been demonstrated, and the need to ensure the safety of the process has been emphasized.

  3. Escherichia coli common pilus (ECP) targets arabinosyl residues in plant cell walls to mediate adhesion to fresh produce plants.

    PubMed

    Rossez, Yannick; Holmes, Ashleigh; Lodberg-Pedersen, Henriette; Birse, Louise; Marshall, Jacqueline; Willats, William G T; Toth, Ian K; Holden, Nicola J

    2014-12-05

    Outbreaks of verotoxigenic Escherichia coli are often associated with fresh produce. However, the molecular basis to adherence is unknown beyond ionic lipid-flagellum interactions in plant cell membranes. We demonstrate that arabinans present in different constituents of plant cell walls are targeted for adherence by E. coli common pilus (ECP; or meningitis-associated and temperature-regulated (Mat) fimbriae) for E. coli serotypes O157:H7 and O18:K1:H7. l-Arabinose is a common constituent of plant cell wall that is rarely found in other organisms, whereas ECP is widespread in E. coli and other environmental enteric species. ECP bound to oligosaccharides of at least arabinotriose or longer in a glycan array, plant cell wall pectic polysaccharides, and plant glycoproteins. Recognition overlapped with the antibody LM13, which binds arabinanase-sensitive pectic epitopes, and showed a preferential affinity for (1→5)-α-linked l-arabinosyl residues and longer chains of arabinan as demonstrated with the use of arabinan-degrading enzymes. Functional adherence in planta was mediated by the adhesin EcpD in combination with the structural subunit, EcpA, and expression was demonstrated with an ecpR-GFP fusion and ECP antibodies. Spinach was found to be enriched for ECP/LM13 targets compared with lettuce. Specific recognition of arabinosyl residues may help explain the persistence of E. coli in the wider environment and association of verotoxigenic E. coli with some fresh produce plants by exploitation of a glycan found only in plant, not animal, cells.

  4. The Relationship Between Pharyngeal Constriction and Post-swallow Residue.

    PubMed

    Stokely, Shauna L; Peladeau-Pigeon, Melanie; Leigh, Chelsea; Molfenter, Sonja M; Steele, Catriona M

    2015-06-01

    Pharyngeal constriction has been proposed as a parameter that may distinguish functional from impaired swallows. We employed anatomically normalized pixel-based measures of pharyngeal area at maximum constriction, and the ratio of this measure to area at rest, and explored the association between these measures and post-swallow residue using the normalized residue ratio scale (NRRS). Videofluoroscopy data for 5 ml boluses of 22 % (w/v) liquid barium were analyzed from 20 healthy young adults and 40 patients with suspected neurogenic dysphagia. The frames of maximum pharyngeal constriction and post-swallow hyoid rest were extracted. Pixel-based measures of pharyngeal area were made using ImageJ and size-normalized using the squared C2-C4 vertebral distance as a reference scalar. Post-swallow residue and the areas of the vallecular and pyriform sinus spaces were measured on the hyoid rest frame to calculate the NRRSv and NRRSp. The dataset was divided into swallows with residue within or exceeding the upper confidence interval boundary seen in the healthy participants. Mixed model repeated measures ANOVAs were used to compare pharyngeal area (rest, constriction) and the pharyngeal constriction ratio, between individuals with and without residue. Measures of pharyngeal area at maximum constriction were significantly larger (i.e., less constricted, p = 0.000) in individuals with post-swallow residue in either the valleculae or the pyriform sinus. These results support the idea that interventions targeted toward improving pharyngeal constriction have the potential to be effective in reducing post-swallow residue.

  5. Interpretation on Recycling Plastics from Shredder Residue

    EPA Pesticide Factsheets

    EPA is considering an interpretation of its regulations that would generally allow for recycling of plastic separated from shredder residue under the conditions described in the Voluntary Procedures for Recycling Plastics from Shredder Residue.

  6. 48 CFR 970.5001 - Residual powers.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Residual powers. 970.5001 Section 970.5001 Federal Acquisition Regulations System DEPARTMENT OF ENERGY AGENCY SUPPLEMENTARY....5001 Residual powers....

  7. 48 CFR 250.104 - Residual powers.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 48 Federal Acquisition Regulations System 3 2010-10-01 2010-10-01 false Residual powers. 250.104 Section 250.104 Federal Acquisition Regulations System DEFENSE ACQUISITION REGULATIONS SYSTEM, DEPARTMENT... Contractual Actions 250.104 Residual powers....

  8. 48 CFR 250.104 - Residual powers.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 48 Federal Acquisition Regulations System 3 2011-10-01 2011-10-01 false Residual powers. 250.104 Section 250.104 Federal Acquisition Regulations System DEFENSE ACQUISITION REGULATIONS SYSTEM, DEPARTMENT... Contractual Actions 250.104 Residual powers....

  9. 48 CFR 970.5001 - Residual powers.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 48 Federal Acquisition Regulations System 5 2014-10-01 2014-10-01 false Residual powers. 970.5001 Section 970.5001 Federal Acquisition Regulations System DEPARTMENT OF ENERGY AGENCY SUPPLEMENTARY....5001 Residual powers....

  10. 48 CFR 1850.104 - Residual powers.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 48 Federal Acquisition Regulations System 6 2012-10-01 2012-10-01 false Residual powers. 1850.104 Section 1850.104 Federal Acquisition Regulations System NATIONAL AERONAUTICS AND SPACE ADMINISTRATION... 1850.104 Residual powers....

  11. 48 CFR 250.104 - Residual powers.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 48 Federal Acquisition Regulations System 3 2014-10-01 2014-10-01 false Residual powers. 250.104 Section 250.104 Federal Acquisition Regulations System DEFENSE ACQUISITION REGULATIONS SYSTEM, DEPARTMENT... Contractual Actions 250.104 Residual powers....

  12. 48 CFR 250.104 - Residual powers.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 48 Federal Acquisition Regulations System 3 2013-10-01 2013-10-01 false Residual powers. 250.104 Section 250.104 Federal Acquisition Regulations System DEFENSE ACQUISITION REGULATIONS SYSTEM, DEPARTMENT... Contractual Actions 250.104 Residual powers....

  13. 48 CFR 1850.104 - Residual powers.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 48 Federal Acquisition Regulations System 6 2013-10-01 2013-10-01 false Residual powers. 1850.104 Section 1850.104 Federal Acquisition Regulations System NATIONAL AERONAUTICS AND SPACE ADMINISTRATION... 1850.104 Residual powers....

  14. 48 CFR 1850.104 - Residual powers.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 48 Federal Acquisition Regulations System 6 2014-10-01 2014-10-01 false Residual powers. 1850.104 Section 1850.104 Federal Acquisition Regulations System NATIONAL AERONAUTICS AND SPACE ADMINISTRATION... 1850.104 Residual powers....

  15. 48 CFR 970.5001 - Residual powers.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 48 Federal Acquisition Regulations System 5 2012-10-01 2012-10-01 false Residual powers. 970.5001 Section 970.5001 Federal Acquisition Regulations System DEPARTMENT OF ENERGY AGENCY SUPPLEMENTARY....5001 Residual powers....

  16. 48 CFR 970.5001 - Residual powers.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 48 Federal Acquisition Regulations System 5 2011-10-01 2011-10-01 false Residual powers. 970.5001 Section 970.5001 Federal Acquisition Regulations System DEPARTMENT OF ENERGY AGENCY SUPPLEMENTARY....5001 Residual powers....

  17. 48 CFR 970.5001 - Residual powers.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 48 Federal Acquisition Regulations System 5 2013-10-01 2013-10-01 false Residual powers. 970.5001 Section 970.5001 Federal Acquisition Regulations System DEPARTMENT OF ENERGY AGENCY SUPPLEMENTARY....5001 Residual powers....

  18. 48 CFR 250.104 - Residual powers.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 48 Federal Acquisition Regulations System 3 2012-10-01 2012-10-01 false Residual powers. 250.104 Section 250.104 Federal Acquisition Regulations System DEFENSE ACQUISITION REGULATIONS SYSTEM, DEPARTMENT... Contractual Actions 250.104 Residual powers....

  19. PESTICIDE RESIDUE RECOVERIES FROM SURFACE WIPES

    EPA Science Inventory

    Human exposure is a consequence of pesticide use indoors with a primary source resulting from residue deposition on household surfaces. Accurate measurements of surface residues is essential for estimating exposure from different routes. Various procedures have been developed ...

  20. Inputs to the Pulp and Paper Industry October 2011 Residual Risk Assessment

    EPA Pesticide Factsheets

    The U.S. Environmental Protection Agency (EPA) has to conduct risk assessments on each source category subject to MACT standards and determine if additional standards are needed to reduce residual risks.

  1. COMBINING METHODS FOR THE REDUCTION OF OXYCHLORINE RESIDUALS IN DRINKING WATER

    EPA Science Inventory

    Previous investigations have shown ferrous iron application to be an effective and economically feasible method of removing residual chlorine dioxide and chlorite iron from drinking water. This treatment, however, was not effective in reducing concentrqations of chlorate iron. ...

  2. 40 CFR 1065.705 - Residual and intermediate residual fuel.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... for Residual Fuel Characteristic Unit Category ISO-F- RMA 30 RMB 30 RMD 80 RME 180 RMF 180 RMG 380 RMH....0 991.0 1010.0 991.0 1010.0 ISO 3675 or ISO 12185: 1996/Cor 1:2001 (see also ISO 8217:2005(E) 7.1). Kinematic viscosity at 50 °C, max cSt 30.0 80.0 180.0 380.0 700.0 ISO 3104:1994/Cor 1:1997. Flash point,...

  3. A Multi-Factor Analysis of Sustainable Agricultural Residue Removal Potential

    SciTech Connect

    Jared Abodeely; David Muth; Paul Adler; Eleanor Campbell; Kenneth Mark Bryden

    2012-10-01

    Agricultural residues have significant potential as a near term source of cellulosic biomass for bioenergy production, but sustainable removal of agricultural residues requires consideration of the critical roles that residues play in the agronomic system. Previous work has developed an integrated model to evaluate sustainable agricultural residue removal potential considering soil erosion, soil organic carbon, greenhouse gas emission, and long-term yield impacts of residue removal practices. The integrated model couples the environmental process models WEPS, RUSLE2, SCI, and DAYCENT. This study uses the integrated model to investigate the impact of interval removal practices in Boone County, Iowa, US. Residue removal of 4.5 Mg/ha was performed annually, bi-annually, and tri-annually and were compared to no residue removal. The study is performed at the soil type scale using a national soil survey database assuming a continuous corn rotation with reduced tillage. Results are aggregated across soil types to provide county level estimates of soil organic carbon changes and individual soil type soil organic matter content if interval residue removal were implemented. Results show interval residue removal is possible while improving soil organic matter. Implementation of interval removal practices provide greater increases in soil organic matter while still providing substantial residue for bioenergy production.

  4. 48 CFR 50.104 - Residual powers.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 48 Federal Acquisition Regulations System 1 2010-10-01 2010-10-01 false Residual powers. 50.104... EXTRAORDINARY CONTRACTUAL ACTIONS AND THE SAFETY ACT Extraordinary Contractual Actions 50.104 Residual powers. This section prescribes standards and procedures for exercising residual powers under Pub. L....

  5. 48 CFR 50.104 - Residual powers.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 48 Federal Acquisition Regulations System 1 2011-10-01 2011-10-01 false Residual powers. 50.104... EXTRAORDINARY CONTRACTUAL ACTIONS AND THE SAFETY ACT Extraordinary Contractual Actions 50.104 Residual powers. This section prescribes standards and procedures for exercising residual powers under Pub. L....

  6. 48 CFR 50.104 - Residual powers.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 48 Federal Acquisition Regulations System 1 2014-10-01 2014-10-01 false Residual powers. 50.104... EXTRAORDINARY CONTRACTUAL ACTIONS AND THE SAFETY ACT Extraordinary Contractual Actions 50.104 Residual powers. This section prescribes standards and procedures for exercising residual powers under Pub. L....

  7. 48 CFR 50.104 - Residual powers.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 48 Federal Acquisition Regulations System 1 2012-10-01 2012-10-01 false Residual powers. 50.104... EXTRAORDINARY CONTRACTUAL ACTIONS AND THE SAFETY ACT Extraordinary Contractual Actions 50.104 Residual powers. This section prescribes standards and procedures for exercising residual powers under Pub. L....

  8. 48 CFR 50.104 - Residual powers.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 48 Federal Acquisition Regulations System 1 2013-10-01 2013-10-01 false Residual powers. 50.104... EXTRAORDINARY CONTRACTUAL ACTIONS AND THE SAFETY ACT Extraordinary Contractual Actions 50.104 Residual powers. This section prescribes standards and procedures for exercising residual powers under Pub. L....

  9. 40 CFR 158.2290 - Residue chemistry.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 24 2014-07-01 2014-07-01 false Residue chemistry. 158.2290 Section... REQUIREMENTS FOR PESTICIDES Antimicrobial Pesticide Data Requirements § 158.2290 Residue chemistry. (a) General... determine the residue chemistry data requirements for antimicrobial pesticide products. Notes that apply...

  10. Low-latency digital frequency synthesizer using the residue number system

    NASA Technical Reports Server (NTRS)

    Chren, William A., Jr.

    1993-01-01

    A low-latency frequency synthesizer using the Direct Digital Synthesis (DDS) technique has been designed. Called the Residue Assisted Frequency Synthesizer (RAFS), it exhibits frequency switching times which are reduced by more than 50 percent below previously published designs. The switching speed advantage is made possible by the use of the Residue Number System, which allows the pipeline lengths in the Phase Accumulator and other circuitry to be reduced significantly.

  11. Chlorpyrifos residual behaviors in field crops and transfers during duck pellet feed processing.

    PubMed

    Li, Rui; Wei, Wei; He, Liang; Hao, Lili; Ji, Xiaofeng; Zhou, Yu; Wang, Qiang

    2014-10-22

    Chlorpyrifos is a widely used organophosphorus pesticide in agricultural crops (including food) and animal feeds in China, resulting in heavy contamination. Many studies have focused on the food-processing effects on chlorpyrifos removal, but sufficient information is not observed for feed-processing steps. Here, chlorpyrifos residual behaviors in field crops and its transfers in duck pellet feed-processing steps were evaluated. In field trials, the highest residues for rice grain, shelled corn, and soybean seed were 12.0, 0.605, and 0.220 mg/kg, respectively. Residues of all rice grain and about half of shelled corn exceeded the maximum residue limits (MRLs) of China, and five soybean seeds exceeded the MRL of China. Chlorpyrifos residue was reduced 38.2% in brown rice after the raw rice grain was hulled. The residue in bran increased 71.2% after milling from brown rice. During the squashing step, the residue reduced 73.8% in soybean meal. The residues reduced significantly (23.7-36.8%) during the process of granulating for rice, maize, and soybean products. Comparatively, the grinding process showed only limited influence on chlorpyrifos removal (<10%). The residues of duck pellet feeds produced from highly contaminated raw materials of this study were 1.01 mg/kg (maize-soybean feed) and 3.20 mg/kg (rice-soybean feed), which were much higher than the generally accepted value (>0.1 mg/kg) for animal feeding. Chlorpyrifos residues were removed significantly by processing steps of pellet feeds, but the residue of raw materials was the determining factor for the safety of duck feeding.

  12. Acid transformation of bauxite residue: Conversion of its alkaline characteristics.

    PubMed

    Kong, Xiangfeng; Li, Meng; Xue, Shengguo; Hartley, William; Chen, Chengrong; Wu, Chuan; Li, Xiaofei; Li, Yiwei

    2017-02-15

    Bauxite residue (BR) is a highly alkaline solid hazardous waste produced from bauxite processing for alumina production. Alkaline transformation appears to reduce the environmental risk of bauxite residue disposal areas (BRDAs) whilst potentially providing opportunities for the sustainable reuse and on-going management of BR. Mineral acids, a novel citric acid and a hybrid combination of acid-gypsum treatments were investigated for their potential to reduce residue pH and total alkalinity and transform the alkaline mineral phase. XRD results revealed that with the exception of andradite, the primary alkaline solid phases of cancrinite, grossular and calcite were transformed into discriminative products based on the transformation used. Supernatants separated from BR and transformed bauxite residue (TBR) displayed distinct changes in soluble Na, Ca and Al, and a reduction in pH and total alkalinity. SEM images suggest that mineral acid transformations promote macro-aggregate formation, and the positive promotion of citric acid, confirming the removal or reduction in soluble and exchangeable Na. NEXAFS analysis of Na K-edge revealed that the chemical speciation of Na in TBRs was consistent with BR. Three acid treatments and gypsum combination had no effect on Na speciation, which affects the distribution of Na revealed by sodium STXM imaging.

  13. Process to recycle shredder residue

    DOEpatents

    Jody, Bassam J.; Daniels, Edward J.; Bonsignore, Patrick V.

    2001-01-01

    A system and process for recycling shredder residue, in which separating any polyurethane foam materials are first separated. Then separate a fines fraction of less than about 1/4 inch leaving a plastics-rich fraction. Thereafter, the plastics rich fraction is sequentially contacted with a series of solvents beginning with one or more of hexane or an alcohol to remove automotive fluids; acetone to remove ABS; one or more of EDC, THF or a ketone having a boiling point of not greater than about 125.degree. C. to remove PVC; and one or more of xylene or toluene to remove polypropylene and polyethylene. The solvents are recovered and recycled.

  14. Outlet baffles: Effect on liquid residuals from zero-gravity draining of hemispherically ended cylinders

    NASA Technical Reports Server (NTRS)

    Symons, E. P.

    1972-01-01

    An experimental investigation was conducted to study the relative effectiveness of various outlet baffles in reducing liquid residuals resulting from the draining of hemispherically ended cylindrical tanks in a weightless environment. Three different baffles were employed. The relative effectiveness of each baffle was determined by comparing the results obtained, in the form of liquid residuals, with results for an unbaffled tank. Data indicate that all the baffles tested reduced residuals. Reductions betweem 10 and 60 percent were obtained, depending on baffle geometry and outlfow Weber number.

  15. 40 CFR 180.519 - Bromide ion and residual bromine; tolerances for residues.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Bromide ion and residual bromine... Tolerances § 180.519 Bromide ion and residual bromine; tolerances for residues. (a) General. The food additives, bromide ion and residual bromine, may be present in water, potable in accordance with...

  16. 40 CFR 180.519 - Bromide ion and residual bromine; tolerances for residues.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 25 2013-07-01 2013-07-01 false Bromide ion and residual bromine... Tolerances § 180.519 Bromide ion and residual bromine; tolerances for residues. (a) General. The food additives, bromide ion and residual bromine, may be present in water, potable in accordance with...

  17. 40 CFR 180.519 - Bromide ion and residual bromine; tolerances for residues.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 25 2012-07-01 2012-07-01 false Bromide ion and residual bromine... Tolerances § 180.519 Bromide ion and residual bromine; tolerances for residues. (a) General. The food additives, bromide ion and residual bromine, may be present in water, potable in accordance with...

  18. 40 CFR 180.519 - Bromide ion and residual bromine; tolerances for residues.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 24 2011-07-01 2011-07-01 false Bromide ion and residual bromine... Tolerances § 180.519 Bromide ion and residual bromine; tolerances for residues. (a) General. The food additives, bromide ion and residual bromine, may be present in water, potable in accordance with...

  19. 40 CFR 180.519 - Bromide ion and residual bromine; tolerances for residues.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 24 2014-07-01 2014-07-01 false Bromide ion and residual bromine... Tolerances § 180.519 Bromide ion and residual bromine; tolerances for residues. (a) General. The food additives, bromide ion and residual bromine, may be present in water, potable in accordance with...

  20. An integrated assessment of the potential of agricultural and forestry residues for energy production in China

    SciTech Connect

    Gao, Ji; Zhang, Aiping; Lam, Shu Kee; Zhang, Xuesong; Thomson, Allison M.; Lin, Erda; Jiang, Kejun; Clarke, Leon E.; Edmonds, James A.; Kyle, Page G.; Yu, Sha; Zhou, Yuyu; Zhou, Sheng

    2016-01-05

    Biomass has been widely recognized as an important energy source with high potential to reduce greenhouse gas emissions while minimizing environmental pollution. In this study, we employ the Global Change Assessment Model to estimate the potential of agricultural and forestry residue biomass for energy production in China. Potential availability of residue biomass as an energy source was analyzed for the 21st century under different climate policy scenarios. Currently, the amount of total annual residue biomass, averaged over 2003-2007, is around 15519PJ in China, consisting of 10818PJ from agriculture residues (70%) and 4701PJ forestry residues (30%). We estimate that 12693PJ of the total biomass is available for energy production, with 66% derived from agricultural residue and 34% from forestry residue. Most of the available residue is from south central China (3347PJ), east China (2862PJ) and south-west China (2229PJ), which combined exceeds 66% of the total national biomass. Under the reference scenario without carbon tax, the potential availability of residue biomass for energy production is projected to be 3380PJ by 2050 and 4108PJ by 2095, respectively. When carbon tax is imposed, biomass availability increases substantially. For the CCS 450ppm scenario, availability of biomass increases to 9002PJ (2050) and 11524PJ (2095), respectively. For the 450ppm scenario without CCS, 9183 (2050) and 11150PJ (2095) residue biomass, respectively, is projected to be available. Moreover, the implementation of CCS will have a little impact on the supply of residue biomass after 2035. Our results suggest that residue biomass has the potential to be an important component in China's sustainable energy production portfolio. As a low carbon emission energy source, climate change policies that involve carbon tariff and CCS technology promote the use of residue biomass for energy production in a low carbon-constrained world.

  1. An essential tyrosine residue of Aspergillus polygalacturonase.

    PubMed

    Stratilová, E; Dzúrová, M; Markovic, O; Jörnvall, H

    1996-03-11

    Based on strict conservation of a tyrosine residue in 24 polygalacturonases, tyrosine modification was assessed in two different forms of the Aspergillus enzyme. The second subform was unknown in structure but submitted to sequence analysis and was found also to have the conserved tyrosine residue. Results of chemical modifications are consistent in showing inactivation of the proteins with all tyrosine-reactive agents tested, acetic anhydride, N-acetyl imidazole, and tetranitromethane. Furthermore, after acetylation, regeneration of enzyme activity was possible with hydroxylamine. Spectrophotometric pH titration showed that one accessible tyrosine residue is ionized at pH 9.3-9.5, whereas the remaining, masked residues are all ionized at pH 10.5. It is concluded that one tyrosine residue is catalytically important, in agreement with the inactivation and reactivation data, that this residue is accessible, and that it is likely to correspond to the strictly conserved residue observed in all forms.

  2. Residual number processing in dyscalculia.

    PubMed

    Cappelletti, Marinella; Price, Cathy J

    2014-01-01

    Developmental dyscalculia - a congenital learning disability in understanding numerical concepts - is typically associated with parietal lobe abnormality. However, people with dyscalculia often retain some residual numerical abilities, reported in studies that otherwise focused on abnormalities in the dyscalculic brain. Here we took a different perspective by focusing on brain regions that support residual number processing in dyscalculia. All participants accurately performed semantic and categorical colour-decision tasks with numerical and non-numerical stimuli, with adults with dyscalculia performing slower than controls in the number semantic tasks only. Structural imaging showed less grey-matter volume in the right parietal cortex in people with dyscalculia relative to controls. Functional MRI showed that accurate number semantic judgements were maintained by parietal and inferior frontal activations that were common to adults with dyscalculia and controls, with higher activation for participants with dyscalculia than controls in the right superior frontal cortex and the left inferior frontal sulcus. Enhanced activation in these frontal areas was driven by people with dyscalculia who made faster rather than slower numerical decisions; however, activation could not be accounted for by response times per se, because it was greater for fast relative to slow dyscalculics but not greater for fast controls relative to slow dyscalculics. In conclusion, our results reveal two frontal brain regions that support efficient number processing in dyscalculia.

  3. RESIDUAL STRESSES IN 3013 CONTAINERS

    SciTech Connect

    Mickalonis, J.; Dunn, K.

    2009-11-10

    The DOE Complex is packaging plutonium-bearing materials for storage and eventual disposition or disposal. The materials are handled according to the DOE-STD-3013 which outlines general requirements for stabilization, packaging and long-term storage. The storage vessels for the plutonium-bearing materials are termed 3013 containers. Stress corrosion cracking has been identified as a potential container degradation mode and this work determined that the residual stresses in the containers are sufficient to support such cracking. Sections of the 3013 outer, inner, and convenience containers, in both the as-fabricated condition and the closure welded condition, were evaluated per ASTM standard G-36. The standard requires exposure to a boiling magnesium chloride solution, which is an aggressive testing solution. Tests in a less aggressive 40% calcium chloride solution were also conducted. These tests were used to reveal the relative stress corrosion cracking susceptibility of the as fabricated 3013 containers. Significant cracking was observed in all containers in areas near welds and transitions in the container diameter. Stress corrosion cracks developed in both the lid and the body of gas tungsten arc welded and laser closure welded containers. The development of stress corrosion cracks in the as-fabricated and in the closure welded container samples demonstrates that the residual stresses in the 3013 containers are sufficient to support stress corrosion cracking if the environmental conditions inside the containers do not preclude the cracking process.

  4. South Polar Residual Ice Cap

    NASA Technical Reports Server (NTRS)

    1990-01-01

    This mosaic is composed of 18 Viking Orbiter images (6 each in red, green, and violet filters), acquired on September 28, 1977, during revolution 407 of Viking Orbiter 2. The south pole is located just off the lower left edge of the polar cap, and the 0 degree longitude meridian extends toward the top of the mosaic. The large crater near the right edge (named 'South') is about 100 km in diameter. These images were acquired during southern summer on Mars (Ls = 341 degrees); the sub-solar declination was 8 degrees S., and the south polar cap was nearing its final stage of retreat just prior to vernal equinox. The south residual cap is approximately 400 km across, and the exposed surface is thought to consist dominantly of carbon-dioxide frost. This is in contrast to the water-ice surface of the north polar residual cap. It is likely that water ice is present in layers that underlie the south polar cap and that comprise the surrounding layered terrains. Near the top of this image, irregular pits with sharp-rimmed cliffs appear 'etched', presumably by wind. A series of rugged mountains (extending toward the upper right corner of the image) are of unknown origin.

  5. 40 CFR 180.432 - Lactofen; tolerances for residues.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Lactofen; tolerances for residues. (a) General. Tolerances are established for residues of the herbicide... for residues of the herbicide lactofen, including its metabolites and degradates, in or on...

  6. 40 CFR 180.432 - Lactofen; tolerances for residues.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Lactofen; tolerances for residues. (a) General. Tolerances are established for residues of the herbicide... for residues of the herbicide lactofen, including its metabolites and degradates, in or on...

  7. 40 CFR 180.432 - Lactofen; tolerances for residues.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Lactofen; tolerances for residues. (a) General. Tolerances are established for residues of the herbicide... for residues of the herbicide lactofen, including its metabolites and degradates, in or on...

  8. 40 CFR 180.432 - Lactofen; tolerances for residues.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Lactofen; tolerances for residues. (a) General. Tolerances are established for residues of the herbicide... for residues of the herbicide lactofen, including its metabolites and degradates, in or on...

  9. Inhibited Release of Mobile Contaminants from Hanford Tank Residual Waste

    SciTech Connect

    Cantrell, Kirk J.; Heald, Steve M.; Arey, Bruce W.; Lindberg, Michael J.

    2011-03-03

    Investigations of contaminant release from Hanford Site tank residual waste have indicated that in some cases certain contaminants of interest (Tc and Cr) exhibit inhibited release. The percentage of Tc that dissolved from residual waste from tanks 241-C-103, 241-C-106, 241-C-202, and 241-C-203 ranged from approximately 6% to 10%. The percent leachable Cr from residual waste from tanks C-103, C 202, and C-203 ranged from approximately 1.1% to 44%. Solid phase characterization results indicate that the recalcitrant forms of these contaminants are associated with iron oxides. X-ray absorption near edge structure analysis of Tc and Cr in residual waste indicates that these contaminants occur in Fe oxide particles as their lower, less soluble oxidation states [Tc(IV) and Cr(III)]. The form of these contaminants is likely as oxides or hydroxides incorporated within the structure of the Fe oxide. Leaching behavior of U from tank residual waste was studied using deionized water, and CaCO3 and Ca(OH)2 saturated solutions as leachants. The release behavior of U from tank residual waste is complex. Initial U concentrations in water and CaCO3 leachants are high due to residual amounts of the highly soluble U mineral cejkaite. As leaching and dilution occur NaUO2PO4 {center_dot} xH2O, Na2U2O7(am) and schoepite (or a similar phase) become the solubility controlling phases for U. In the case of the Ca(OH)2 leachant, U release from tank residual waste is dramatically reduced. Thermodynamic modeling indicates that the solubility of CaUO4(c) controls release of U from residual waste in the Ca(OH)2 leachants. It is assumed the solubility controlling phase is actually a hydrated version of CaUO4 with a variable water content ranging from CaUO4 to CaUO4 {center_dot} (H2O). The critically reviewed value for CaUO4(c) (log KSP0 = 15.94) produced good agreement with our experimental data for the Ca(OH)2 leachates.

  10. Prediction of residual shear strength of corroded reinforced concrete beams

    NASA Astrophysics Data System (ADS)

    Imam, Ashhad; Azad, Abul Kalam

    2016-09-01

    With the aim of providing experimental data on the shear capacity and behavior of corroded reinforced concrete beams that may help in the development of strength prediction models, the test results of 13 corroded and four un-corroded beams are presented. Corrosion damage was induced by accelerated corrosion induction through impressed current. Test results show that loss of shear strength of beams is mostly attributable to two important damage factors namely, the reduction in stirrups area due to corrosion and the corrosion-induced cracking of concrete cover to stirrups. Based on the test data, a method is proposed to predict the residual shear strength of corroded reinforced concrete beams in which residual shear strength is calculated first by using corrosion-reduced steel area alone, and then it is reduced by a proposed reduction factor, which collectively represents all other applicable corrosion damage factors. The method seems to yield results that are in reasonable agreement with the available test data.

  11. The regulation of flow through residual spray nozzles

    PubMed Central

    Lonergan, Richard P.; Hall, Lawrence B.

    1959-01-01

    Used residual spray nozzles, which have been discarded because of the increase in discharge rates, may be used again if their discharge rates are reduced by a metering orifice placed in the nozzle tip. A suitable orifice in a polyethylene disc is described. On the basis of laboratory test results, such a disc appears to be an inexpensive and satisfactory metering device for use in combination with worn spray nozzles. PMID:14418102

  12. Sorption characteristics of polycyclic aromatic hydrocarbons in aluminum smelter residues

    SciTech Connect

    Gijs D. Breedveld; Emilien Pelletier; Richard St. Louis; Gerard Cornelissen

    2007-04-01

    High temperature carbon oxidation in primary aluminum smelters results in the release of polycyclic aromatic hydrocarbons (PAH) into the environment. The main source of PAH are the anodes, which are composed of petroleum coke (black carbon, BC) and coal tar pitch. To elucidate the dominant carbonaceous phase controlling the environmental fate of PAH in aluminum smelter residues (coke BC and/or coal tar), the sorptive behavior of PAHs has been determined, using passive samplers and infinite-sink desorption methods. Samples directly from the wet scrubber were studied as well as ones from an adjacent 20-year old storage lagoon and roof dust from the smelter. Carbon-normalized distribution coefficients of native PAHs were 2 orders of magnitude higher than expected based on amorphous organic carbon (AOC)/water partitioning, which is in the same order of magnitude as reported literature values for soots and charcoals. Sorption isotherms of laboratory-spiked deuterated phenanthrene showed strong (about 100 times stronger than AOC) but nonetheless linear sorption in both fresh and aged aluminum smelter residues. The absence of nonlinear behavior typical for adsorption to BC indicates that PAH sorption in aluminum smelter residues is dominated by absorption into the semi-solid coal tar pitch matrix. Desorption experiments using Tenax showed that fresh smelter residues had a relatively large rapidly desorbing fraction of PAH (35-50%), whereas this fraction was strongly reduced (11-16%) in the lagoon and roof dust material. Weathering of the coal tar residue and/or redistribution of PAH between coal tar and BC phases could explain the reduced availability in aged samples. 38 refs., 5 figs., 1 tab.

  13. Implication of an unfavorable residue (Thr346) in intrinsic flexibility of firefly luciferase.

    PubMed

    Moradi, Maryam; Hosseinkhani, Saman; Emamzadeh, Rahman

    2012-09-10

    In order to better understand the functional role of an unusual residue (Thr346) of firefly luciferase mutagenesis at this residue was performed. Firefly luciferase, catalyzes the bioluminescence reaction and is an excellent tool as a reporter in nano-system biology studies. Nonetheless, the enzyme rapidly loses its activity at temperatures above 30 °C and this leads to reduced sensitivity and precision in analytical applications. Residue Thr346 in a connecting loop (341-348) of firefly luciferase is located in a disallowed region of Ramachandran plot. In this study, we have substituted this residue (T346) with anomalous dihedral angles with Val, Gly and Pro to clarify the role of this residue in structure and function of the enzyme using site-directed mutagenesis. Substitution of this unfavorable residue (T346) with atypical dihedral angles (ψ, φ) with other residues brought about an increase of thermostability and decrease of specific activity. Structural and functional properties of the mutants were analyzed using different spectroscopic methods. It seems that this residue is a critically conserved residue to support the functional flexibility for a fast kinetic bioluminescence reaction at the expense of lower stability.

  14. Characterization and electrolytic cleaning of poly(methyl methacrylate) residues on transferred chemical vapor deposited graphene

    NASA Astrophysics Data System (ADS)

    Sun, Jianbo; Finklea, Harry O.; Liu, Yuxin

    2017-03-01

    Poly(methyl methacrylate) (PMMA) residue has long been a critical challenge for practical applications of the transferred chemical vapor deposited (CVD) graphene. Thermal annealing is empirically used for the removal of the PMMA residue; however experiments imply that there are still small amounts of residues left after thermal annealing which are hard to remove with conventional methods. In this paper, the thermal degradation of the PMMA residue upon annealing was studied by Raman spectroscopy. The study reveals that post-annealing residues are generated by the elimination of methoxycarbonyl side chains in PMMA and are believed to be absorbed on graphene via the π–π interaction between the conjugated unsaturated carbon segments and graphene. The post-annealing residues are difficult to remove by further annealing in a non-oxidative atmosphere due to their thermal and chemical stability. An electrolytic cleaning method was shown to be effective in removing these post-annealing residues while preserving the underlying graphene lattice based on Raman spectroscopy and atomic force microscopy studies. Additionally, a solution-gated field effect transistor was used to study the transport properties of the transferred CVD graphene before thermal annealing, after thermal annealing, and after electrolytic cleaning, respectively. The results show that the carrier mobility was significantly improved, and that the p-doping was reduced by removing PMMA residues and post-annealing residues. These studies provide a more in-depth understanding on the thermal annealing process for the removal of the PMMA residues from transferred CVD graphene and a new approach to remove the post-annealing residues, resulting in a residue-free graphene.

  15. Characterization and electrolytic cleaning of poly(methyl methacrylate) residues on transferred chemical vapor deposited graphene.

    PubMed

    Sun, Jianbo; Finklea, Harry O; Liu, Yuxin

    2017-03-24

    Poly(methyl methacrylate) (PMMA) residue has long been a critical challenge for practical applications of the transferred chemical vapor deposited (CVD) graphene. Thermal annealing is empirically used for the removal of the PMMA residue; however experiments imply that there are still small amounts of residues left after thermal annealing which are hard to remove with conventional methods. In this paper, the thermal degradation of the PMMA residue upon annealing was studied by Raman spectroscopy. The study reveals that post-annealing residues are generated by the elimination of methoxycarbonyl side chains in PMMA and are believed to be absorbed on graphene via the π-π interaction between the conjugated unsaturated carbon segments and graphene. The post-annealing residues are difficult to remove by further annealing in a non-oxidative atmosphere due to their thermal and chemical stability. An electrolytic cleaning method was shown to be effective in removing these post-annealing residues while preserving the underlying graphene lattice based on Raman spectroscopy and atomic force microscopy studies. Additionally, a solution-gated field effect transistor was used to study the transport properties of the transferred CVD graphene before thermal annealing, after thermal annealing, and after electrolytic cleaning, respectively. The results show that the carrier mobility was significantly improved, and that the p-doping was reduced by removing PMMA residues and post-annealing residues. These studies provide a more in-depth understanding on the thermal annealing process for the removal of the PMMA residues from transferred CVD graphene and a new approach to remove the post-annealing residues, resulting in a residue-free graphene.

  16. The potential of residues of furfural and biogas as calcareous soil amendments for corn seed production.

    PubMed

    Zhao, Yunchen; Yan, Zhibin; Qin, Jiahai; Ma, Zhijun; Zhang, Youfu; Zhang, Li

    2016-04-01

    Intensive corn seed production in Northwest of China produced large amounts of furfural residues, which represents higher treatment cost and environmental issue. The broad calcareous soils in the Northwest of China exhibit low organic matter content and high pH, which led to lower fertility and lower productivity. Recycling furfural residues as soil organic and nutrient amendment might be a promising agricultural practice to calcareous soils. A 3-year field study was conducted to evaluate the effects of furfural as a soil amendment on corn seed production on calcareous soil with compared to biogas residues. Soil physical-chemical properties, soil enzyme activities, and soil heavy metal concentrations were assessed in the last year after the last application. Corn yield was determined in each year. Furfural residue amendments significantly decreased soil pH and soil bulk density. Furfural residues combined with commercial fertilizers resulted in the greater cumulative on soil organic matter, total phosphorus, available phosphorus, available potassium, and cation exchange capacity than that of biogas residue. Simultaneously, urease, invertase, catalase, and alkaline phosphatase increased even at the higher furfural application rates. Maize seed yield increased even with lower furfural residue application rates. Furfural residues resulted in lower Zn concentration and higher Cd concentration than that of biogas residues. Amendment of furfural residues led to higher soil electrical conductivity (EC) than that of biogas residues. The addition of furfural residues to maize seed production may be considered to be a good strategy for recycling the waste, converting it into a potential resource as organic amendment in arid and semi-arid calcareous soils, and may help to reduce the use of mineral chemical fertilizers in these soils. However, the impact of its application on soil health needs to be established in long-term basis.

  17. Detection of antibiotic residues in poultry meat.

    PubMed

    Sajid, Abdul; Kashif, Natasha; Kifayat, Nasira; Ahmad, Shabeer

    2016-09-01

    The antibiotic residues in poultry meat can pose certain hazards to human health among them are sensitivity to antibiotics, allergic reactions, mutation in cells, imbalance of intestinal micro biota and bacterial resistance to antibiotics. The purpose of the present paper was to detect antibiotic residue in poultry meat. During the present study a total of 80 poultry kidney and liver samples were collected and tested for detection of different antibiotic residues at different pH levels Eschericha coli at pH 6, 7 and Staphyloccocus aureus at pH 8 & 9. Out of 80 samples only 4 samples were positive for antibiotic residues. The highest concentrations of antibiotic residue found in these tissues were tetracycline (8%) followed by ampicilin (4%), streptomycine (2%) and aminoglycosides (1%) as compared to other antibiotics like sulfonamides, neomycine and gentamycine. It was concluded that these microorganism at these pH levels could be effectively used for detection of antibiotic residues in poultry meat.

  18. Measuring the reduced shear

    NASA Astrophysics Data System (ADS)

    Zhang, Jun

    2011-11-01

    Neglecting the second order corrections in weak lensing measurements can lead to a few percent uncertainties on cosmic shears, and becomes more important for cluster lensing mass reconstructions. Existing methods which claim to measure the reduced shears are not necessarily accurate to the second order when a point spread function (PSF) is present. We show that the method of Zhang (2008) exactly measures the reduced shears at the second order level in the presence of PSF. A simple theorem is provided for further confirming our calculation, and for judging the accuracy of any shear measurement method at the second order based on its properties at the first order. The method of Zhang (2008) is well defined mathematically. It does not require assumptions on the morphologies of galaxies and the PSF. To reach a sub-percent level accuracy, the CCD pixel size is required to be not larger than 1/3 of the Full Width at Half Maximum (FWHM) of the PSF, regardless of whether the PSF has a power-law or exponential profile at large distances. Using a large ensemble (gtrsim107) of mock galaxies of unrestricted morphologies, we study the shear recovery accuracy under different noise conditions. We find that contaminations to the shear signals from the noise of background photons can be removed in a well defined way because they are not correlated with the source shapes. The residual shear measurement errors due to background noise are consistent with zero at the sub-percent level even when the amplitude of such noise reaches about 1/10 of the source flux within the half-light radius of the source. This limit can in principle be extended further with a larger galaxy ensemble in our simulations. On the other hand, the source Poisson noise remains to be a cause of systematic errors. For a sub-percent level accuracy, our method requires the amplitude of the source Poisson noise to be less than 1/80 ~ 1/100 of the source flux within the half-light radius of the source, corresponding to

  19. Measuring the reduced shear

    SciTech Connect

    Zhang, Jun

    2011-11-01

    Neglecting the second order corrections in weak lensing measurements can lead to a few percent uncertainties on cosmic shears, and becomes more important for cluster lensing mass reconstructions. Existing methods which claim to measure the reduced shears are not necessarily accurate to the second order when a point spread function (PSF) is present. We show that the method of Zhang (2008) exactly measures the reduced shears at the second order level in the presence of PSF. A simple theorem is provided for further confirming our calculation, and for judging the accuracy of any shear measurement method at the second order based on its properties at the first order. The method of Zhang (2008) is well defined mathematically. It does not require assumptions on the morphologies of galaxies and the PSF. To reach a sub-percent level accuracy, the CCD pixel size is required to be not larger than 1/3 of the Full Width at Half Maximum (FWHM) of the PSF, regardless of whether the PSF has a power-law or exponential profile at large distances. Using a large ensemble (∼>10{sup 7}) of mock galaxies of unrestricted morphologies, we study the shear recovery accuracy under different noise conditions. We find that contaminations to the shear signals from the noise of background photons can be removed in a well defined way because they are not correlated with the source shapes. The residual shear measurement errors due to background noise are consistent with zero at the sub-percent level even when the amplitude of such noise reaches about 1/10 of the source flux within the half-light radius of the source. This limit can in principle be extended further with a larger galaxy ensemble in our simulations. On the other hand, the source Poisson noise remains to be a cause of systematic errors. For a sub-percent level accuracy, our method requires the amplitude of the source Poisson noise to be less than 1/80 ∼ 1/100 of the source flux within the half-light radius of the source

  20. Study on the residual stress relaxation in girth-welded steel pipes under bending load using diffraction methods

    DOE PAGES

    Hempel, Nico; Bunn, Jeffrey R.; Nitschke-Pagel, Thomas; ...

    2017-02-02

    This research is dedicated to the experimental investigation of the residual stress relaxation in girth-welded pipes due to quasi-static bending loads. Ferritic-pearlitic steel pipes are welded with two passes, resulting in a characteristic residual stress state with high tensile residual stresses at the weld root. Also, four-point bending is applied to generate axial load stress causing changes in the residual stress state. These are determined both on the outer and inner surfaces of the pipes, as well as in the pipe wall, using X-ray and neutron diffraction. Focusing on the effect of tensile load stress, it is revealed that notmore » only the tensile residual stresses are reduced due to exceeding the yield stress, but also the compressive residual stresses for equilibrium reasons. Furthermore, residual stress relaxation occurs both parallel and perpendicular to the applied load stress.« less

  1. Detecting ketamine in beverage residues: Application in date rape detection.

    PubMed

    Albright, Jessica A; Stevens, Sarah A; Beussman, Douglas J

    2012-05-01

    Ketamine can be used to facilitate date-rape when unknowingly spiked into a victim's beverage. If a biological sample is not available from the victim, the beverage container might be the only remaining source of forensic evidence. We present a rapid, simple analysis method for the detection of ketamine in wet or dry beverage residues based on liquid chromatography-mass spectrometry (LC-MS). Wet residues consist of the final few drops (<1 ml) in a container while dry residues are the remains once all liquid has evaporated. By using LC-MS, which readily handles aqueous samples, often no derivatization or sample extraction is needed, thus reducing analysis time and lab technician involvement. Tandem mass spectrometry (MS/MS) provides an enhancement in both selectivity and sensitivity. We have studied a range of beverages and determined limits of detection between 1.2 × 10-3 and 1.3 × 10-4 mg/ml, compared to 0.21-0.85 mg/ml used in most date-rape scenarios. This paper represents the first published report of using LC-MS/MS for the analysis of beverage residues for the presence of a date-rape drug. This method could replace the current gas chromatography-mass spectrometry (GC-MS) methods and provide a faster, more selective method for the analysis of date-rape drugs, requiring virtually no sample preparation.

  2. THERMAL RESIDUAL STRESSES IN BILAYERED, TRILAYERED AND GRADED DENTAL CERAMICS

    PubMed Central

    Fabris, Douglas; Souza, Júlio C.M.; Silva, Filipe S.; Fredel, Márcio; Mesquita-Guimarães, Joana; Zhang, Yu; Henriques, Bruno

    2017-01-01

    Layered ceramic systems are usually hit by residual thermal stresses created during cooling from high processing temperature. The purpose of this study was to determine the thermal residual stresses at different ceramic multi-layered systems and evaluate their influence on the bending stress distribution. Finite elements method was used to evaluate the residual stresses in zirconia-porcelain and alumina-porcelain multi-layered discs and to simulate the ‘piston-on-ring’ test. Temperature-dependent material properties were used. Three different multi-layered designs were simulated: a conventional bilayered design; a trilayered design, with an intermediate composite layer with constant composition; and a graded design, with an intermediate layer with gradation of properties. Parameters such as the interlayer thickness and composition profiles were varied in the study. Alumina-porcelain discs present smaller residual stress than the zirconia-porcelain discs, regardless of the type of design. The homogeneous interlayer can yield a reduction of ~40% in thermal stress relative to bilayered systems. Thinner interlayers favoured the formation of lower thermal stresses. The graded discs showed the lowest thermal stresses for a gradation profile given by power law function with p=2. The bending stresses were significantly affected by the thermal stresses in the discs. The risk of failure for all-ceramic dental restorative systems can be significantly reduced by using trilayered systems (homogenous or graded interlayer) with the proper design. PMID:28163345

  3. Residual Strength Prediction of Fuselage Structures with Multiple Site Damage

    NASA Technical Reports Server (NTRS)

    Chen, Chuin-Shan; Wawrzynek, Paul A.; Ingraffea, Anthony R.

    1999-01-01

    This paper summarizes recent results on simulating full-scale pressure tests of wide body, lap-jointed fuselage panels with multiple site damage (MSD). The crack tip opening angle (CTOA) fracture criterion and the FRANC3D/STAGS software program were used to analyze stable crack growth under conditions of general yielding. The link-up of multiple cracks and residual strength of damaged structures were predicted. Elastic-plastic finite element analysis based on the von Mises yield criterion and incremental flow theory with small strain assumption was used. A global-local modeling procedure was employed in the numerical analyses. Stress distributions from the numerical simulations are compared with strain gage measurements. Analysis results show that accurate representation of the load transfer through the rivets is crucial for the model to predict the stress distribution accurately. Predicted crack growth and residual strength are compared with test data. Observed and predicted results both indicate that the occurrence of small MSD cracks substantially reduces the residual strength. Modeling fatigue closure is essential to capture the fracture behavior during the early stable crack growth. Breakage of a tear strap can have a major influence on residual strength prediction.

  4. Microwave calcination for plutonium immobilization and residue stabilization

    SciTech Connect

    Harris, M.J.; Rising, T.L.; Roushey, W.J.; Sprenger, G.S.

    1995-12-01

    In the late 1980`s development was begun on a process using microwave energy to vitrify low level mixed waste sludge and transuranic mixed waste sludge generated in Building 374 at Rocky Flats. This process was shown to produce a dense, highly durable waste form. With the cessation of weapons production at Rocky Flats, the emphasis has changed from treatment of low level and TRU wastes to stabilizaiton of plutonium oxide and residues. This equipment is versatile and can be used as a heat source to calcine, react or vitrify many types of residues and oxides. It has natural economies in that it heats only the material to be treated, significantly reducing cycle times over conventional furnaces. It is inexpensive to operate in that most of the working components remain outside of any necessary contamination enclosure and therefore can easily be maintained. Limited testing has been successfully performed on cerium oxide (as a surrogate for plutonium oxide), surrogate electrorefining salts, surrogate residue sludge and residue ash. Future plans also include tests on ion exchange resins. In an attempt to further the usefullness of this technology, a mobile, self-contained microwave melting system is currently under development and expected to be operational at Rocky Flats Enviromental Technology Site by the 4th quarter of FY96.

  5. Modeling the oxidation of methionine residues by peroxides in proteins.

    PubMed

    Chennamsetty, Naresh; Quan, Yong; Nashine, Vishal; Sadineni, Vikram; Lyngberg, Olav; Krystek, Stanley

    2015-04-01

    We report the use of molecular modeling to predict the oxidation propensity of methionine residues in proteins. Oxidation of methionine to the sulfoxide form is one of the major degradation pathways for therapeutic proteins. Oxidation can occur during production, formulation, or storage of pharmaceuticals and it often reduces or eliminates biological activity. We use a molecular model based on atomistic simulations called 2-shell water coordination number to predict the oxidation rates for several model proteins and therapeutic candidates. In addition, we implement models that are based on static and simulation average of the solvent-accessible area (SAA) for either the side chain or the sulfur atom in the methionine residue. We then compare the results from the different models against the experimentally measured relative rates of methionine oxidation. We find that both the 2-shell model and the simulation-averaged SAA models are accurate in predicting the oxidation propensity of methionine residues for the proteins tested. We also find the appropriate parameter ranges where the models are most accurate. These models have significant predictive power and can be used to enable further protein engineering or to guide formulation approaches in stabilizing the unstable methionine residues.

  6. Studies Of Residual Flexibility And Vibration Testing

    NASA Technical Reports Server (NTRS)

    Admire, John R.; Tinker, Michael L.; Bookout, Paul S.; Ivey, Edward W.

    1995-01-01

    Collection of reports presents theoretical and experimental studies in which concept of residual flexibility applied to modal vibration testing and verification of mathematical models of vibrations of flexible structure constrained by another structure. "Residual flexibility" denotes that part of interface flexibility due to mode shapes out of frequency range of test. Studies directed toward assessing residual-flexibility approach as substitute for fixed-base vibrational testing of payloads installed in spacecraft.

  7. Residual stresses in polymer matrix composite laminates

    NASA Technical Reports Server (NTRS)

    Hahn, H. T.

    1976-01-01

    Residual stresses in composites are induced during fabrication and by environmental exposure. The theory formulated can describe the shrinkage commonly observed after a thermal expansion test. Comparison between the analysis and experimental data for laminates of various material systems indicates that the residual stress-free temperature can be lower than the curing temperature, depending on the curing process. Effects of residual stresses on ply failure including the acoustic emission characteristics are discussed.

  8. Use of MRF residue as alternative fuel in cement production.

    PubMed

    Fyffe, John R; Breckel, Alex C; Townsend, Aaron K; Webber, Michael E

    2016-01-01

    that using MRF residue to produce SRF for use in cement kilns is likely an advantageous alternative to disposal of the residue in landfills. The use of SRF can offset fossil fuel use, reduce CO2 emissions, and divert energy-dense materials away from landfills. For this test-case, the use of SRF offset between 7700 and 8700 Mg of coal use, reduced CO2 emissions by at least 1.4%, and diverted over 7950 Mg of energy-dense materials away from landfills. In addition, emissions were reduced by at least 19% for SO2, while NOX emissions increased by between 16% and 24%. Changes in emissions of particulate matter, mercury, hydrogen chloride, and total-hydrocarbons were all less than plus or minus 2.2%, however these emissions were not measured at the cement kiln. Co-location of MRFs, SRF production facilities, and landfills can increase the benefits of SRF use even further by reducing transportation requirements.

  9. Particulate residue separators for harvesting devices

    DOEpatents

    Hoskinson, Reed L.; Kenney, Kevin L.; Wright, Christopher T.; Hess, John R.

    2010-06-29

    A particulate residue separator and a method for separating a particulate residue stream may include a plenum borne by a harvesting device, and have a first, intake end and a second, exhaust end; first and second particulate residue air streams which are formed by the harvesting device and which travel, at least in part, along the plenum and in a direction of the second, exhaust end; and a baffle assembly which is located in partially occluding relation relative to the plenum, and which substantially separates the first and second particulate residue air streams.

  10. Methods of separating particulate residue streams

    DOEpatents

    Hoskinson, Reed L.; Kenney, Kevin L.; Wright, Christopher T.; Hess, J. Richard

    2011-04-05

    A particulate residue separator and a method for separating a particulate residue stream may include an air plenum borne by a harvesting device, and have a first, intake end and a second, exhaust end; first and second particulate residue air streams that are formed by the harvesting device and that travel, at least in part, along the air plenum and in a direction of the second, exhaust end; and a baffle assembly that is located in partially occluding relation relative to the air plenum and that substantially separates the first and second particulate residue air streams.

  11. Saccharification of pumpkin residues by coculturing of Trichoderma reesei RUT-C30 and Phanerochaete chrysosporium Burdsall with delayed inoculation timing.

    PubMed

    Yang, Rui; Meng, Demei; Hu, Xiaosong; Ni, Yuanying; Li, Quanhong

    2013-09-25

    Trichoderma reesei and Phanerochaete chrysosporium with different lignocellulose-degrading enzyme systems have received much attention due to their ability to biodegrade lignocellulosic biomass. However, the synergistic effect of the two fungi on lignocellulose degradation is unknown. Herein, a cocultivation of T. reesei RUT-C30 and P. chrysosporium Burdsall for biodegradation of lignocellulosic pumpkin residues (PRS) was developed to produce soluble saccharide. Results indicated that a cocultivation of the two fungi with P. chrysosporium Burdsall inoculation delayed for 1.5 days produced the highest saccharide yield of 53.08% (w/w), and only 20.83% (w/w) of PRS were left after one batch of fermentation. In addition, this strategy increased the activities of secreted cellulases (endoglucanase, cellobiohydrolase, and β-glucosidase) and ligninases (lignin peroxidase and manganese peroxidase), which correlated to the increased saccharide yield. Besides, the resulting monosaccharides including glucose (1.23 mg/mL), xylose (0.13 mg/mL), arabinose (0.46 mg/mL), and fructose (0.21 mg/mL) from cocultures exhibited much higher yields than those from monoculture, which provides basal information for further fermentation research. This bioconversion of PRS into soluble sugars by cocultured fungal species provides a low cost method based on lignocellulose for potential biofuels or other bioproduct production.

  12. Application of neutron diffraction to measure residual strains in high temperature composites

    SciTech Connect

    Saigal, A. . Dept. of Mechanical Engineering); Kupperman, D.S. )

    1991-01-01

    An experimental neutron diffraction technique was used to measure residual thermal strains developed in high temperature composites during postfabrication cooling. Silicon carbide fiber-reinforced titanium aluminide (over the temperature range 20--950{degree}C) and tungsten and saphikon fiber-reinforced nickel aluminide composites (at room temperature) were investigated. As a result of thermal expansion mismatch, compressive residual strains and stresses were generated in the silicon carbide fibers during cooldown. The axial residual strains were tensile in the matrix and were lower in nickel aluminide matrix as compared to those in titanium aluminide matrix. The average transverse residual strains in the matrix were compressive. Liquid-nitrogen dipping and thermal-cycling tend to reduce the fabrication-induced residual strains in silicon carbide fiber-reinforced titanium aluminide matrix composite. However, matrix cracking can occur as a result of these processes. 10 refs., 5 figs., 2 tabs.

  13. Air pollution control residues from waste incineration: Current UK situation and assessment of alternative technologies

    SciTech Connect

    Amutha Rani, D.; Boccaccini, A.R.; Deegan, D.; Cheeseman, C.R.

    2008-11-15

    Current disposal options for APC residues in the UK and alternative treatment technologies developed world-wide have been reviewed. APC residues are currently landfilled in the UK where they undergo in situ solidification, although the future acceptability of this option is uncertain because the EU waste acceptance criteria (WAC) introduce strict limits on leaching that are difficult to achieve. Other APC residue treatment processes have been developed which are reported to reduce leaching to below relevant regulatory limits. The Ferrox process, the VKI process, the WES-PHix process, stabilisation/solidification using cementitious binders and a range of thermal treatment processes are reviewed. Thermal treatment technologies convert APC residues combined with other wastes into inert glass or glass-ceramics that encapsulate heavy metals. The waste management industry will inevitably use the cheapest available option for treating APC residues and strict interpretation and enforcement of waste legislation is required if new, potentially more sustainable technologies are to become commercially viable.

  14. Partitioning Residue-derived and Residue-induced Emissions of N2O Using 15N-labelled Crop Residues

    NASA Astrophysics Data System (ADS)

    Farrell, R. E.; Carverhill, J.; Lemke, R.; Knight, J. D.

    2014-12-01

    Estimates of N2O emissions in Canada indicate that 17% of all agriculture-based emissions are associated with the decomposition of crop residues. However, research specific to the western Canadian prairies (including Saskatchewan) has shown that the N2O emission factor for N sources in this region typically ranges between 0.2 and 0.6%, which is well below the current IPCC default emission factor of 1.0%. Thus, it stands to reason that emissions from crop residues should also be lower than those calculated using the current IPCC emission factor. Current data indicates that residue decomposition, N mineralization and N2O production are affected by a number of factors such as C:N ratio and chemical composition of the residue, soil type, and soil water content; thus, a bench-scale incubation study was conducted to examine the effects of soil type and water content on N2O emissions associated with the decomposition of different crop residues. The study was carried out using soils from the Black, Dark Brown, Brown, and Gray soil zones and was conducted at both 50% and 70% water-filled pore space (WFPS); the soils were amended with 15N-labeled residues of wheat, pea, canola, and flax, or with an equivalent amount of 15N-labeled urea; 15N2O production was monitored using a Picarro G5101-i isotopic N2O analyzer. Crop residue additions to the soils resulted in both direct and indirect emissions of N2O, with residue derived emissions (RDE; measured as 15N2O) generally exceeding residue-induced emissions (RIE) at 50% WFPS—with RDEs ranging from 42% to 88% (mean = 58%) of the total N2O. Conversely, at 70% WFPS, RDEs were generally lower than RIEs—ranging from 21% to 83% (mean = 48%). Whereas both water content and soil type had an impact on N2O production, there was a clear and consistent trend in the emission factors for the residues; i.e., emissions were always greatest for the canola residue and lowest for the wheat residue and urea fertilizer; and intermediate for pea

  15. Effects of crop residue returning on nitrous oxide emissions in agricultural soils

    NASA Astrophysics Data System (ADS)

    Shan, Jun; Yan, Xiaoyuan

    2013-06-01

    Crop residue returning is a common practice in agricultural system that consequently influences nitrous oxide (N2O) emissions. Much attention has been focused on the effects of crop residue on N2O release. However, no systematic result has yet been drawn because environmental factors among different studies vary. A meta-analysis was described to integrate 112 scientific assessments of crop residue returning on N2O emissions in this study. Results showed that crop residue returning, when averaged across all studies, had no statistically significant effect on N2O release compared with control treatments. However, the range of effects of crop residue returning on N2O emission was significantly affected by synthetic nitrogen (N) fertilizer application, type of crop residue, specific manner in which crop residue has returned, and type of land-use. N2O release was significantly inhibited by 11.7% and 27.1% (P < 0.05) when crop residue was with synthetic N fertilizer and when type of land-use was paddy, respectively. While N2O emissions were significantly enhanced by 42.1% and 23.5% (P < 0.05) when crop residue was applied alone and when type of land-use was upland, respectively. N2O emissions were likewise increased when crop residue with lower C/N ratio was used, mulching of crop residue was performed, and type of land-use was fallow. Our study provides the first quantitative analysis of crop residue returning on N2O emissions, indicating that crop residue returning has no statistically significant effect on N2O release at regional scale, and underlining that the Intergovernmental Panel on Climate Change guidelines should take the opposite effects of crop residue returning on upland and paddy into account when estimating the N2O emission factor of crop residue for different land-use types. Given that most of data are dominated by certain types of crop residue and specific application methods, more field data are required to reduce uncertainty.

  16. Catalyst deactivation in residue hydrocracking

    SciTech Connect

    Oballa, M.C.; Wong, C.; Krzywicki, A.

    1994-12-31

    The existence of a computer-controlled bench scale hydrocracking units at the authors site has made cheaper the non-stop running of experiments for long periods of time. It was, therefore possible to show, at minimal costs, when three hydrocracking catalysts in service reach their maximum lifetime. Different parameters which are helpful for catalyst life and activity predictions were calculated, e.g., relative catalyst age and the effectiveness factor. Experimental results compared well with model, giving them the minimum and maximum catalyst lifetime, as well as the deactivation profile with regard to sulfur and metals removal. Reaction rate constants for demetallization and desulfurization were also determined. Six commercial catalysts were evaluated at short term runs and the three most active were used for long term runs. Out of three catalysts tested for deactivation at long term runs, it was possible to choose one whose useful life was higher than the others. All runs were carried out in a Robinson-Mahoney continuous flow stirred tank reactor, using 50/50 volumetric mixture of Cold Lake/Lloydminster atmospheric residue and NiMo/Al{sub 2}O{sub 3} catalyst.

  17. Gunshot residue preservation in seawater.

    PubMed

    Lindström, Anne-Christine; Hoogewerff, Jurian; Athens, Josie; Obertova, Zuzana; Duncan, Warwick; Waddell, Neil; Kieser, Jules

    2015-08-01

    Little is known about the persistence of gunshot residue (GSR) in soft tissue and bones during decomposition in marine environments. For a better understanding, qualitative and quantitative data were obtained on GSR retention on soft tissue and bony gunshot wounds (GSWs). A quantity of 36 fleshed and 36 defleshed bovine ribs were shot at contact range with 0.22 calibre hollow point ammunition using a Stirling 0.22 calibre long rifle. Bone specimens in triplicate were placed in three environments: submerged, intertidal and in supralittoral zone. Sets of triplicates were recovered on day 3, 10, 24 and 38, and analysed with scanning electron microscopy with energy dispersive X-ray spectrometry (SEM-EDX), and inductive coupled plasma mass spectrometry (ICP-MS). The SEM-EDX recorded GSR-indicative particles surrounding the bullet entrance on all bone types (fleshed and defleshed) in all environments throughout the study. GSR-unique particles were only detected on the supralittoral bones. The ICP-MS analysis showed faster GSR loss on submerged than intertidal and supralittoral defleshed specimens. Fleshed specimens showed a faster GSR loss on intertidal than submerged and supralittoral specimens. In conclusion, the GSR disappeared faster from submerged and intertidal than non-submerged specimens. The difference of detection of GSR between analysed specimens (defleshed versus fleshed) disappeared upon defleshing. This study highlights the potential of finding evidence of GSR in a submerged body and the potential of microscopic and analytical methods for examining suspected GSW in highly decomposed bodies in marine habitats.

  18. Thermal Insulation from Hardwood Residues

    NASA Astrophysics Data System (ADS)

    Sable, I.; Grinfelds, U.; Vikele, L.; Rozenberga, L.; Zeps, M.; Luguza, S.

    2015-11-01

    Adequate heat is one of the prerequisites for human wellbeing; therefore, building insulation is required in places where the outside temperature is not suitable for living. The climate change, with its rising temperatures and longer dry periods, promotes enlargement of the regions with conditions more convenient for hardwood species than for softwood species. Birch (Betula pendula) is the most common hardwood species in Latvia. The aim of this work was to obtain birch fibres from wood residues of plywood production and to form low-density thermal insulation boards. Board formation and production was done in the presence of water; natural binder, fire retardant and fungicide were added in different concentrations. Board properties such as density, transportability or resistance to particulate loss, thermal conductivity and reaction to fire were investigated. This study included thermal insulation boards with the density of 102-120 kg/m3; a strong correlation between density and the binder amount was found. Transportability also improved with the addition of a binder, and 0.1-0.5% of the binder was the most appropriate amount for this purpose. The measured thermal conductivity was in the range of 0.040-0.043 W/(m·K). Fire resistance increased with adding the fire retardant. We concluded that birch fibres are applicable for thermal insulation board production, and it is possible to diversify board properties, changing the amount of different additives.

  19. Fgd residues: a commercial opportunity

    SciTech Connect

    Juzwiak, J.H.; Smith, C.L. )

    1992-01-01

    This paper focuses on actual operating experience in the handling and processing of ash and FGD by-products by Conversion Systems at the Orlando Utility Commission Stanton Energy Center at Orlando, Florida. The discussion discloses how the Poz-O-Tec stabilization technology, the most widely used disposal technology for wet FGD sludge, has been modified and improved to maximize the by-product recycling and produce the most cost effective disposal option. Recently, CSI has directed 100% of the Stanton Facility FGD stabilization production into the generation of the commercial aggregate called Poz-O-Lite Aggregate. This aggregate product is used in the manufacture of concrete block, replacing ordinary crushed stone. CSI has been able to develop this reuse application using the low permeability and superior strength of the stabilized material. The utility also benefits from the stabilized material which is not recycled as it offers opportunity for co-disposal of other combustion residues from some of the utility's oil fired plants in cells that are lined and then capped with the stabilized material. In summary, virtually all production of the by-products, from combustion or flue gas desulfurization at the Stanton Energy Center are now being used for commercial application, except that specifically required as liners for the disposal of other materials on site.

  20. Effect of fruit and vegetable processing on reduction of synthetic pyrethroid residues.

    PubMed

    Chauhan, Reena; Kumari, Beena; Rana, M K

    2014-01-01

    In this review, we emphasize that the advantages associated with applying pesticides to enhance agricultural productivity must be weighed against the possible health hazards arising from the appearance of toxic pesticide residues in food. First and foremost, pesticides should be handled and applied in compliance with good agricultural practices to minimize environmental or food commodity contamination.In developing countries, good agricultural practices are not fully abided by.When vegetables are produced in such countries, pesticides are applied or prospectively applied at each growth stage of the crop. Hence, contamination of vegetables and other food commodities occur. It is well known that processing of food derived from pesticide treated crop commodities can serve to reduce residues that reach consumers. Food safety can therefore partially be enhanced by employing suitable food processing techniques and appropriate storage periods, even in developing countries. Even common and simple household processing techniques for certain foods acquire significance as means to reduce the intake of harmful pesticide food residues.Pesticide residue levels in post-harvest raw agricultural commodities (RAC) are affected by the storage, handling and the processing steps they pass through, while being prepared for human consumption. The review of cogent literature presented in this article demonstrated differences among the pyrethroid insecticide residues present on or in foods, depending on how the RAC from which they came were processed for consumption. Peeling vegetables or fruit reduced pyrethroid residues the most (60-100% ), and juicing was nearly as effective in reducing residues (70-100% ). The least reduction occurred for foodstuffs that were only washed with tap water (I 0-70% ). Washing RACs with saline water and detergent was more effective(34-60%) in reducing residues than was simple washing under tap water. Freezing is also effective in reducing residue levels and

  1. Use of Combined Uncertainty of Pesticide Residue Results for Testing Compliance with Maximum Residue Limits (MRLs).

    PubMed

    Farkas, Zsuzsa; Slate, Andrew; Whitaker, Thomas B; Suszter, Gabriella; Ambrus, Árpád

    2015-05-13

    The uncertainty of pesticide residue levels in crops due to sampling, estimated for 106 individual crops and 24 crop groups from residue data obtained from supervised trials, was adjusted with a factor of 1.3 to accommodate the larger variability of residues under normal field conditions. Further adjustment may be necessary in the case of mixed lots. The combined uncertainty of residue data including the contribution of sampling is used for calculation of an action limit, which should not be exceeded when compliance with maximum residue limits is certified as part of premarketing self-control programs. On the contrary, for testing compliance of marketed commodities the residues measured in composite samples should be greater than or equal to the decision limit calculated only from the combined uncertainty of the laboratory phase of the residue determination. The options of minimizing the combined uncertainty of measured residues are discussed. The principles described are also applicable to other chemical contaminants.

  2. Characterization Report on Sand, Slag, and Crucible Residues and on Fluoride Residues

    SciTech Connect

    Murray, A.M.

    1999-02-10

    This paper reports on the chemical characterization of the sand, slag, and crucible (SS and C) residues and the fluoride residues that may be shipped from the Rocky Flats Environmental Technology Site (RFETS) to Savannah River Site (SRS).

  3. Reduction of pesticide residues in tomatoes and other produce.

    PubMed

    Al-Taher, Fadwa; Chen, Yang; Wylie, Philip; Cappozzo, Jack

    2013-03-01

    There is interest in reducing pesticide residues in fruits and vegetables in order to minimize human exposure. The objectives of this study were to (i) determine the effect of various washing treatments with and without sonication on pesticide removal from tomatoes and (ii) assess the effectiveness of a water wash on select samples using a produce-washing flume. In the first set of experiments, tomatoes were contaminated with acephate, malathion, carbaryl, bifenthrin, cypermethrin, permethrin, cyhalothrin, chlorothalonil, and imidacloprid and were dried overnight. Subsets of the tomatoes were then washed (10°C, 1 min) with one of the following: water, sodium hypochlorite (80 μg/ml, pH 7), peroxyacetic acid (80 μg/ml), or Tween 20 (0.1%) with and without sonication. In general, the effect of sonication depended on the washing treatment and on the pesticide. A separate experiment measured pesticide residues in contaminated samples before and after being washed in a flume (22°C, 1 min). Pesticide residues in contaminated produce were reduced from about 40 to 90% when washed for 1 min in the flume.

  4. Reduction of azinphos-methyl, chlorpyrifos, esfenvalerate, and methomyl residues in processed apples.

    PubMed

    Zabik, M J; El-Hadidi, M F; Cash, J N; Zabik, M E; Jones, A L

    2000-09-01

    McIntosh, Red Delicious, and Golden Delicious from two years of experimental spray programs using azinphos-methyl, chlorpyrifos, esfenvalerate, and methomyl were processed into frozen apple slices, applesauce, single-strength juice, and juice concentrate. Residue levels were expressed as micrograms per 150 g of apple or the equivalent amount of apple product to calculate the percentage change in these pesticides brought about by processing. Producing single-strength apple juice reduced azinphos-methyl, chlorpyrifos, esfenvalerate, and methomyl residues by 97.6, 100, 97.8, and 78.1%, respectively. Production of applesauce reduced all four compounds by >/=95%. Azinphos-methyl, chlorpyrifos, esfenvalerate, and methomyl residues were reduced in apple slices by 94.1, 85.7, 98.6, and 94.7%, respectively. Processing is shown to be very effective in reducing the levels of these pesticides.

  5. Influence of Surface Properties and Impact Conditions on Adhesion of Insect Residues

    NASA Technical Reports Server (NTRS)

    Wohl, Christopher J.; Smith, Joseph G.; Connell, John W.; Siochi, Emilie J.; Doss, Jereme R.; Shanahan, Michelle H.; Penner, Ronald K.

    2015-01-01

    Insect residues can cause premature transition to turbulent flow on laminar flow airfoils. Engineered surfaces that mitigate the adhesion of insect residues provide, therefore, a route to more efficient aerodynamics and reduced fuel burn rates. Areal coverage and heights of residues depend not only on surface properties, but also on impact conditions. We report high speed photography of fruit fly impacts at different angles of inclination on a rigid aluminum surface, optical microscopy and profilometry, and contact angle goniometry to support the design of engineered surfaces. For the polyurethane and epoxy coatings studied, some of which exhibited superhydrophobicity, it was determined that impact angle and surface compositions play critical roles in the efficacy of these surfaces to reduce insect residue adhesion.

  6. High residue amounts of kaolin further increase photosynthesis and fruit color in 'Empire' apple

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Kaolin (Surround WP, NovaSource, Phoenix, AZ, USA) is commonly used to reduce sunburn damage in fruit crops and to reduce heat stress on foliage. It is typically applied at rates of 3% to 6%, resulting in leaf and fruit residue levels of 1-3 g/m2. Crop modeling of the effect of kaolin on leaf/cano...

  7. Dynamics of Potassium Release and Adsorption on Rice Straw Residue

    PubMed Central

    Li, Jifu; Lu, Jianwei; Li, Xiaokun; Ren, Tao; Cong, Rihuan; Zhou, Li

    2014-01-01

    Straw application can not only increase crop yields, improve soil structure and enrich soil fertility, but can also enhance water and nutrient retention. The aim of this study was to ascertain the relationships between straw decomposition and the release-adsorption processes of K+. This study increases the understanding of the roles played by agricultural crop residues in the soil environment, informs more effective straw recycling and provides a method for reducing potassium loss. The influence of straw decomposition on the K+ release rate in paddy soil under flooded condition was studied using incubation experiments, which indicated the decomposition process of rice straw could be divided into two main stages: (a) a rapid decomposition stage from 0 to 60 d and (b) a slow decomposition stage from 60 to 110 d. However, the characteristics of the straw potassium release were different from those of the overall straw decomposition, as 90% of total K was released by the third day of the study. The batches of the K sorption experiments showed that crop residues could adsorb K+ from the ambient environment, which was subject to decomposition periods and extra K+ concentration. In addition, a number of materials or binding sites were observed on straw residues using IR analysis, indicating possible coupling sites for K+ ions. The aqueous solution experiments indicated that raw straw could absorb water at 3.88 g g−1, and this rate rose to its maximum 15 d after incubation. All of the experiments demonstrated that crop residues could absorb large amount of aqueous solution to preserve K+ indirectly during the initial decomposition period. These crop residues could also directly adsorb K+ via physical and chemical adsorption in the later period, allowing part of this K+ to be absorbed by plants for the next growing season. PMID:24587364

  8. Thermal Stability of Residual Stresses in Ti-6Al-4V components

    NASA Astrophysics Data System (ADS)

    Stanojevic, A.; Angerer, P.; Oberwinkler, B.

    2016-03-01

    The need for light weight design while maintaining a high safety is essential for many components, especially in the aircraft industry. Therefore, it's important to consider every aspect to reduce weight, improve fatigue life and maintain safety of crucial components. Residual stresses are a major factor which can positively influence components and fulfil all three requirements. However, due to the inconstancy of the behaviour of residual stresses during the life time of a component, residual stresses are often neglected. If the behaviour of residual stresses could be described reliably over the entire life time of a component, residual stresses could be taken into account and components could be optimized even further. Mechanical and thermal loads are the main reason for relaxation of residual stresses. This work covers the thermal stability of residual stresses in Ti-6Al-4V components. Therefore, exposure tests at raised temperatures were performed on specimens with different surface conditions. Residual stresses were measured by x-ray diffraction before and after testing. Creep tests were also carried out to describe the creep behaviour and thereby the ability for residual stress relaxation. A correlation between the creep rate and amount of relaxed stress was found. The creep behaviour of the material was described by using a combination of the Norton Power law and the Arrhenius equation. The Zener-Wert-Avrami model was used to describe the residual stress relaxation. With these models a satisfying correlation between measured and calculated data was found. Hence, the relaxation of residual stresses due to thermal load was described reliably.

  9. RECOVERY OF URANIUM VALUES FROM RESIDUES

    DOEpatents

    Schaap, W.B.

    1959-08-18

    A process is described for the recovery of uranium from insoluble oxide residues resistant to repeated leaching with mineral acids. The residue is treated with gaseous hydrogen fluoride, then with hydrogen and again with hydrogen fluoride, preferably at 500 to 700 deg C, prior to the mineral acid leaching.

  10. 48 CFR 1450.104 - Residual powers.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Residual powers. 1450.104 Section 1450.104 Federal Acquisition Regulations System DEPARTMENT OF THE INTERIOR CONTRACT MANAGEMENT EXTRAORDINARY CONTRACTUAL ACTIONS AND THE SAFETY ACT Extraordinary Contractual Actions 1450.104 Residual powers....

  11. Residuals Management and Water Pollution Control Planning.

    ERIC Educational Resources Information Center

    Environmental Protection Agency, Washington, DC. Office of Public Affairs.

    This pamphlet addresses the problems associated with residuals and water quality especially as it relates to the National Water Pollution Control Program. The types of residuals and appropriate management systems are discussed. Additionally, one section is devoted to the role of citizen participation in developing management programs. (CS)

  12. 48 CFR 1450.104 - Residual powers.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 48 Federal Acquisition Regulations System 5 2014-10-01 2014-10-01 false Residual powers. 1450.104 Section 1450.104 Federal Acquisition Regulations System DEPARTMENT OF THE INTERIOR CONTRACT MANAGEMENT EXTRAORDINARY CONTRACTUAL ACTIONS AND THE SAFETY ACT Extraordinary Contractual Actions 1450.104 Residual powers....

  13. 48 CFR 1450.104 - Residual powers.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 48 Federal Acquisition Regulations System 5 2013-10-01 2013-10-01 false Residual powers. 1450.104 Section 1450.104 Federal Acquisition Regulations System DEPARTMENT OF THE INTERIOR CONTRACT MANAGEMENT EXTRAORDINARY CONTRACTUAL ACTIONS AND THE SAFETY ACT Extraordinary Contractual Actions 1450.104 Residual powers....

  14. 48 CFR 1450.104 - Residual powers.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 48 Federal Acquisition Regulations System 5 2012-10-01 2012-10-01 false Residual powers. 1450.104 Section 1450.104 Federal Acquisition Regulations System DEPARTMENT OF THE INTERIOR CONTRACT MANAGEMENT EXTRAORDINARY CONTRACTUAL ACTIONS AND THE SAFETY ACT Extraordinary Contractual Actions 1450.104 Residual powers....

  15. 48 CFR 1450.104 - Residual powers.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 48 Federal Acquisition Regulations System 5 2011-10-01 2011-10-01 false Residual powers. 1450.104 Section 1450.104 Federal Acquisition Regulations System DEPARTMENT OF THE INTERIOR CONTRACT MANAGEMENT EXTRAORDINARY CONTRACTUAL ACTIONS AND THE SAFETY ACT Extraordinary Contractual Actions 1450.104 Residual powers....

  16. Residue management: Back to the roots

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Addressing the issues of climate change and sustainable biomass feedstocks have soil as a common theme. Managing crop residues is directly related to soil management. Understanding how soil and crop residue management interact provides insight on how to assure agricultural soil can serve as a carbon...

  17. Distribution of veterinary drug residues among muscles

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The U.S. Food and Drug Administration sets tolerances for veterinary drug residues in muscle, but does not specify which muscle should be sampled for analysis. The goal of this research was to determine if antibiotic residue levels are dependent on muscle type. In this study, penicillin G (Pen G) d...

  18. BOOSTER CHLORINATION FOR MANAGING DISINFECTANT RESIDUALS

    EPA Science Inventory

    Booster chlorination is an approach to residual maintenance in which chlorine is applied at strategic locations within the distribution system. Situations in which booster chlorination may be most effective for maintaining a residual are explained informally in the context of a ...

  19. Unicystic ameloblastoma arising from a residual cyst

    PubMed Central

    Mahajan, Amit D; Manjunatha, Bhari Sharanesha; Khurana, Neha M; Shah, Navin

    2014-01-01

    Intraoral swellings involving alveolar ridges in edentulous patients are clinically diagnosed as residual cysts, traumatic bone cysts, Stafne's jaw bone cavity, ameloblastoma and metastatic tumours of the jaw. This case report describes a residual cyst in a 68-year-old edentulous male patient which was enucleated and histopathologically confirmed as a unicystic ameloblastoma. PMID:25199192

  20. Crop Residues: The Rest of the Story

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A recent scientific publication stated that to remove CO2 from the atmosphere, the most permanent and rapid solution would be to sink crop residues to the ocean floor where they would be buried in deep ocean sediments. However, mitigating rising atmospheric CO2 concentrations by removing crop residu...

  1. Tank 12H residuals sample analysis report

    SciTech Connect

    Oji, L. N.; Shine, E. P.; Diprete, D. P.; Coleman, C. J.; Hay, M. S.

    2015-06-11

    The Savannah River National Laboratory (SRNL) was requested by Savannah River Remediation (SRR) to provide sample preparation and analysis of the Tank 12H final characterization samples to determine the residual tank inventory prior to grouting. Eleven Tank 12H floor and mound residual material samples and three cooling coil scrape samples were collected and delivered to SRNL between May and August of 2014.

  2. 40 CFR 240.208 - Residue.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Residue. 240.208 Section 240.208 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES GUIDELINES FOR THE THERMAL PROCESSING OF SOLID WASTES Requirements and Recommended Procedures § 240.208 Residue....

  3. Multi-state complex angular momentum residues

    NASA Astrophysics Data System (ADS)

    Thylwe, Karl-Erik

    2006-09-01

    A relation between a multi-state complex angular momentum (CAM) pole residue and the corresponding CAM-state wavefunction is derived for a real symmetric potential matrix. The result generalizes a residue formula available for single-channel atomical collision systems and it is based on a diagonalization of the S matrix together with the use of exact Wronskian relations.

  4. Residue contact-count potentials are as effective as residue-residue contact-type potentials for ranking protein decoys

    PubMed Central

    Bolser, Dan M; Filippis, Ioannis; Stehr, Henning; Duarte, Jose; Lappe, Michael

    2008-01-01

    Background For over 30 years potentials of mean force have been used to evaluate the relative energy of protein structures. The most commonly used potentials define the energy of residue-residue interactions and are derived from the empirical analysis of the known protein structures. However, single-body residue 'environment' potentials, although widely used in protein structure analysis, have not been rigorously compared to these classical two-body residue-residue interaction potentials. Here we do not try to combine the two different types of residue interaction potential, but rather to assess their independent contribution to scoring protein structures. Results A data set of nearly three thousand monomers was used to compare pairwise residue-residue 'contact-type' propensities to single-body residue 'contact-count' propensities. Using a large and standard set of protein decoys we performed an in-depth comparison of these two types of residue interaction propensities. The scores derived from the contact-type and contact-count propensities were assessed using two different performance metrics and were compared using 90 different definitions of residue-residue contact. Our findings show that both types of score perform equally well on the task of discriminating between near-native protein decoys. However, in a statistical sense, the contact-count based scores were found to carry more information than the contact-type based scores. Conclusion Our analysis has shown that the performance of either type of score is very similar on a range of different decoys. This similarity suggests a common underlying biophysical principle for both types of residue interaction propensity. However, several features of the contact-count based propensity suggests that it should be used in preference to the contact-type based propensity. Specifically, it has been shown that contact-counts can be predicted from sequence information alone. In addition, the use of a single-body term allows

  5. Persistence and effect of processing on chlorpyriphos residues in tomato (Lycopersicon esculantum Mill.).

    PubMed

    Rani, Mamta; Saini, Sunayana; Kumari, Beena

    2013-09-01

    Persistence of chlorpyriphos in tomato was studied following applications of Action 505EC at 800 and 1600 g ha(-1) with active application of chlorpyriphos as 400 and 800 g a.i. ha(-1). The average initial deposits of chlorpyriphos were 0.155 and 0.372 mg kg(-1) on tomato fruits on application of ready-mix formulation, Action 505EC at single and double dose, respectively. The residues dissipated with half- life period of 4.43 days at single dose and 4.38 days at double dose following pseudo first order kinetics.Residues of chlorpyriphos in both the doses on 0 day were below maximum residue limit (MRL) of 0.5 mg kg(-1). Processing was found very effective in reducing the residues of chlorpyriphos in tomato fruits. By washing, reduction of chlorpyriphos was in the range of 41-44 per cent. Washing followed by boiling reduced the residues from 89 to 91% whereas peeling removed residues from 62 to 64%. In soil samples, residues of chlorpyriphos reached below detectable level of 0.010 mg kg(-1) after 5 and 10 days after spray at single and double dose, respectively.

  6. Ionic-liquid pretreatment of cassava residues for the cogeneration of fermentative hydrogen and methane.

    PubMed

    Cheng, Jun; Zhang, Jiabei; Lin, Richen; Liu, Jianzhong; Zhang, Li; Cen, Kefa

    2017-03-01

    An ionic liquid of N-methylmorpholine-N-oxide (NMMO) was used to effectively pretreat cassava residues for the efficient enzymatical hydrolysis and cogeneration of fermentative hydrogen and methane. The reducing sugar yield of enzymolysed cassava residues with NMMO pretreatment improved from 36 to 42g/100g cassava residues. Scanning electron microscopy images revealed the formation of deep grooves (∼4μm wide) and numerous pores in the cassava residues pretreated with NMMO. X-ray diffraction patterns showed that the crystallinity coefficient of NMMO-pretreated cassava residues decreased from 40 to 34. Fourier transform infrared spectra indicated that crystal cellulose I was partially transformed to amorphous cellulose II in the NMMO-pretreated cassava residues. This transformation resulted in a reduced crystallinity index from 0.85 to 0.77. Hydrogen yield from the enzymolysed cassava residues pretreated with NMMO increased from 92.3 to 126mL/gTVS, and the sequential methane yield correspondingly increased from 79.4 to 101.6mL/g TVS.

  7. Residuals and the Residual-Based Statistic for Testing Goodness of Fit of Structural Equation Models

    ERIC Educational Resources Information Center

    Foldnes, Njal; Foss, Tron; Olsson, Ulf Henning

    2012-01-01

    The residuals obtained from fitting a structural equation model are crucial ingredients in obtaining chi-square goodness-of-fit statistics for the model. The authors present a didactic discussion of the residuals, obtaining a geometrical interpretation by recognizing the residuals as the result of oblique projections. This sheds light on the…

  8. Lamination residual strains and stresses in hybrid laminates

    NASA Technical Reports Server (NTRS)

    Daniel, I. M.; Liber, T.

    1977-01-01

    An investigation is conducted of the effects of hybridization on the magnitude of lamination residual stresses. Eight-ply graphite/Kevlar 49/epoxy and graphite/S-glass/epoxy laminates were studied. The same matrix resin was selected for all basic materials to ensure compatibility and uniform curing of the various plies. The specimens, with inserted strain gages and thermocouples, were subjected to curing and postcuring cycles in an autoclave. Subsequently, the specimens were subjected to a thermal cycle from room temperature to 444 K and down to room temperature. It was found that hydridizing reduces apparently residual strains and stresses in the graphite plies. However, these strains were not affected much by the type and degree of hybridization.

  9. Bubble core field modification by residual electrons inside the bubble

    SciTech Connect

    Wu Haicheng; Xie Baisong; Zhao Xueyan; Zhang Shan; Hong Xueren; Liu Mingping

    2010-11-15

    Bubble core field modification due to the nondepleted electrons present inside the bubble is investigated theoretically. These residual electrons induce charge and current densities that can induce the bubble core field modification as well as the bubble shape change. It is found that the electrons entering into the bubble move backward at almost light speed and would weaken the transverse bubble fields. This reduces the ratio of longitudinal to transverse radius of the bubble. For the longitudinal bubble field, two effects compensate with each other because of their competition between the enhancement by the shortening of bubble shape and the reduction by the residual electrons. Therefore the longitudinal field is hardly changeable. As a comparison we perform particle-in-cell simulations and it is found that the results from theoretical consideration are consistent with simulation results. Implication of the modification of fields on bubble electron acceleration is also discussed briefly.

  10. Presence of metals in biomass residues after pyrolysis

    NASA Astrophysics Data System (ADS)

    Guehenneux, G.; Varin, S.; Baussand, P.

    2003-05-01

    In contribution to research into renewable energy, pyrolysis tests are run to develop the process of pyrolysis of biomass allowing the production of Hydrogen. Various families of combustibles (oleaginous, lignocellulosics, and seeds) have been tested at different temperatures. The pyrolysis of biomass is hampered by technical problems such as the blockage of the furnace by tars. The residues are collected and treated in a solution of chloric and nitric acid, so that the mineral part is extracted and then analysed by ICP. The first results indicate the presence ofmetals: Ni, Mg, Zn, Mn, Fe... Various proposais for the use of these residues so as to avoid pollution due to their accumulation have been put forward. These ashes can be recombined with fuels, acting as catalysts to reduce the formation of tar and increase the production of hydrogen.

  11. Radiation induced modification of tryptophan and tyrosine residues in flavocytochrome b 2 in dilute aqueous solution

    NASA Astrophysics Data System (ADS)

    Bhattacharya, D.; Saha, A.; Mandal, P. C.

    2000-07-01

    Steady state gamma irradiation of an aqueous solution of flavocytochrome b 2 under different conditions led to modification of tryptophan and tyrosine residues. These aromatic amino acid residues were more susceptible to the attack by OH radicals than H atoms. Unchanged quantum yield values for tryptophan and tyrosine residues and unchanged tryptophan excited state lifetime in the irradiated enzyme suggests that irradiation results in breakage of some non-covalent bonds disrupting the peptide framework partially. It is justified by the circular dichroic studies for the irradiated enzyme which shows a reduced helicity but no evolution towards any other structures.

  12. Research on the residual stress of glass ceramic based on rotary ultrasonic drilling

    NASA Astrophysics Data System (ADS)

    Sun, Lipeng; Jin, Yuzhu; Chen, Jianhua

    2016-10-01

    In the process of machining, the glass ceramic is easy to crack and damage, etc. And the residual stress in the machined surface may cause the crack to different extent in the later stage. Some may even affect the performance of the product. The residual stress of rotary ultrasonic drilling and mechanical processing is compared in different machining parameters (spindle speed, feed rate). The effects of processing parameters and methods are researched, in order to reduce the residual stress in the mechanical processing of glass ceramic, and provide guidance for the actual processing.

  13. A Multi Residue GC-MS Method for Determination of 12 Pesticides in Cucumber

    PubMed Central

    Nasiri, Azadeh; Amirahmadi, Maryam; Mousavi, Zahra; Shoeibi, Shahram; Khajeamiri, Alireza; Kobarfard, Farzad

    2016-01-01

    Cucumber is one of the main vegetables in Iranian food basket. A wide range of pesticides are used for crops protection during the cultivation of vegetables such as cucumber due to heavy pest infestation. Analysis of pesticide residues in food and other environmental commodities have become essential requirement for consumers, producers, and food quality control authorities. This study was aimed at determination of pesticides residues in cucumber as a main vegetable in Iranian food basket. A reliable, rapid and accurate method based on spiked calibration curves and modified QuEChERS sample preparation was developed for determination of 12 pesticide residues in cucumber by gas chromatography-mass spectrometry (GC/MS). The use of spiked calibration standards for constructing the calibration curve substantially reduced adverse matrix-related effects. The recovery of pesticides at 5 concentration levels (n = 3) was in the range of 80.6-112.3. The method was proved to be repeatable with RSD lower than 20%. The limits of detection and quantification for all pesticides were <10 ng/g and <25 ng/g, respectively. The developed method was used for simultaneous determination of the selected pesticides in 60 greenhouse and garden cucumber samples. Among the 60 analyzed samples, 41.7% of them were contaminated with pesticide residues which 31.7% of samples had pesticide residues lower than maximum residue limit and 10% of samples had residue higher than maximum residue limit. PMID:28243277

  14. Prediction and Optimization of Residual Stresses on Machined Surface and Sub-Surface in MQL Turning

    NASA Astrophysics Data System (ADS)

    Ji, Xia; Zou, Pan; Li, Beizhi; Rajora, Manik; Shao, Yamin; Liang, Steven Y.

    Residual stress in the machined surface and subsurface is affected by materials, machining conditions, and tool geometry and can affect the component life and service quality significantly. Empirical or numerical experiments are commonly used for determining residual stresses but these are very expensive. There has been an increase in the utilization of minimum quantity lubrication (MQL) in recent years in order to reduce the cost and tool/part handling efforts, while its effect on machined part residual stress, although important, has not been explored. This paper presents a hybrid neural network that is trained using Simulated Annealing (SA) and Levenberg-Marquardt Algorithm (LM) in order to predict the values of residual stresses in cutting and radial direction on the surface and within the work piece after the MQL face turning process. Once the ANN has successfully been trained, an optimization procedure, using Genetic Algorithm (GA), is applied in order to find the best cutting conditions in order to minimize the surface tensile residual stresses and maximize the compressive residual stresses within the work piece. The optimization results show that the usage of MQL decreases the surface tensile residual stresses and increases the compressive residual stresses within the work piece.

  15. Residues of veterinary drugs at injection sites.

    PubMed

    Reeves, P T

    2007-02-01

    Residues of veterinary drugs have potential implications for human food safety and international trade in animal-derived food commodities. A particular concern is the slow depletion of residues of some injectable formulations from the site of administration. Licensing authorities have adopted different approaches to the human food safety assessment of injection site residues. European agencies apply the maximum residue limit (MRL) for muscle to muscle at the injection site and specify a withdrawal period sufficient to ensure the ingestion of a 300 g portion of muscle, if comprised entirely of injection site tissue, does not exceed the acceptable daily intake. The agencies in Australia, Canada and the USA also exclude injection site residues from the MRL-setting process. These agencies evaluate the risk to consumers posed by potential acute manifestations resulting from the infrequent ingestion of injection site residues based on acute dietary exposure considerations. While all of these approaches protect the safety of consumers, the adoption of different approaches has potential implications for residue surveillance programs in the international trade in meat. In particular, when an exporting country establishes standards for residues at injection sites based on acute dietary exposure considerations and the importing country assesses these residues against the MRL for muscle, the unnecessary condemnation of meat and disruption to market access may result. The latter may represent a potential economical impost to the exporting country. An internationally harmonized approach to the risk analysis of residues of veterinary drugs at injection sites, which protects the safety of consumers and facilitates the international trade in meat, is needed.

  16. Residual macrovascular risk in 2013: what have we learned?

    PubMed Central

    2014-01-01

    Cardiovascular disease poses a major challenge for the 21st century, exacerbated by the pandemics of obesity, metabolic syndrome and type 2 diabetes. While best standards of care, including high-dose statins, can ameliorate the risk of vascular complications, patients remain at high risk of cardiovascular events. The Residual Risk Reduction Initiative (R3i) has previously highlighted atherogenic dyslipidaemia, defined as the imbalance between proatherogenic triglyceride-rich apolipoprotein B-containing-lipoproteins and antiatherogenic apolipoprotein A-I-lipoproteins (as in high-density lipoprotein, HDL), as an important modifiable contributor to lipid-related residual cardiovascular risk, especially in insulin-resistant conditions. As part of its mission to improve awareness and clinical management of atherogenic dyslipidaemia, the R3i has identified three key priorities for action: i) to improve recognition of atherogenic dyslipidaemia in patients at high cardiometabolic risk with or without diabetes; ii) to improve implementation and adherence to guideline-based therapies; and iii) to improve therapeutic strategies for managing atherogenic dyslipidaemia. The R3i believes that monitoring of non-HDL cholesterol provides a simple, practical tool for treatment decisions regarding the management of lipid-related residual cardiovascular risk. Addition of a fibrate, niacin (North and South America), omega-3 fatty acids or ezetimibe are all options for combination with a statin to further reduce non-HDL cholesterol, although lacking in hard evidence for cardiovascular outcome benefits. Several emerging treatments may offer promise. These include the next generation peroxisome proliferator-activated receptorα agonists, cholesteryl ester transfer protein inhibitors and monoclonal antibody therapy targeting proprotein convertase subtilisin/kexin type 9. However, long-term outcomes and safety data are clearly needed. In conclusion, the R3i believes that ongoing trials with

  17. Residual Strength Analyses of Monolithic Structures

    NASA Technical Reports Server (NTRS)

    Forth, Scott (Technical Monitor); Ambur, Damodar R. (Technical Monitor); Seshadri, B. R.; Tiwari, S. N.

    2003-01-01

    Finite-element fracture simulation methodology predicts the residual strength of damaged aircraft structures. The methodology uses the critical crack-tip-opening-angle (CTOA) fracture criterion to characterize the fracture behavior of the material. The CTOA fracture criterion assumes that stable crack growth occurs when the crack-tip angle reaches a constant critical value. The use of the CTOA criterion requires an elastic- plastic, finite-element analysis. The critical CTOA value is determined by simulating fracture behavior in laboratory specimens, such as a compact specimen, to obtain the angle that best fits the observed test behavior. The critical CTOA value appears to be independent of loading, crack length, and in-plane dimensions. However, it is a function of material thickness and local crack-front constraint. Modeling the local constraint requires either a three-dimensional analysis or a two-dimensional analysis with an approximation to account for the constraint effects. In recent times as the aircraft industry is leaning towards monolithic structures with the intention of reducing part count and manufacturing cost, there has been a consistent effort at NASA Langley to extend critical CTOA based numerical methodology in the analysis of integrally-stiffened panels.In this regard, a series of fracture tests were conducted on both flat and curved aluminum alloy integrally-stiffened panels. These flat panels were subjected to uniaxial tension and during the test, applied load-crack extension, out-of-plane displacements and local deformations around the crack tip region were measured. Compact and middle-crack tension specimens were tested to determine the critical angle (wc) using three-dimensional code (ZIP3D) and the plane-strain core height (hJ using two-dimensional code (STAGS). These values were then used in the STAGS analysis to predict the fracture behavior of the integrally-stiffened panels. The analyses modeled stable tearing, buckling, and crack

  18. Elucidating residue roles in engineered variants of AraC regulatory protein

    PubMed Central

    Tang, Shuang-Yan; Cirino, Patrick C

    2010-01-01

    The AraC regulatory protein was previously engineered to control gene expression specifically in response to d-arabinose and not the native effector l-arabinose (Tang et al., J Am Chem Soc 2008;130:5267–5271). Mutations were targeted in the ligand-binding pocket and on the AraC N-terminal arm, which plays an important role in maintaining repressing or activating conformations in the absence or presence of effector, respectively. In this study, we analyze the contributions of individual mutations toward the overall mutant functions in an attempt to streamline future AraC design efforts. For a variety of point mutants, we quantify the induced expression response to d-arabinose (level of leaky expression, induction fold, half-maximal dose response, and effector specificity) and the binding affinity of the purified ligand-binding domain for d-arabinose. We find that mutations introduced in the N-terminal arm (design Position 8) strengthen the induction response, most likely by weakening interactions with the DNA-binding domain, but are not involved in ligand binding. Meanwhile, binding pocket mutations occurring further away from the arm (Positions 80 and 82) primarily contribute to maintaining repression in the absence of effector and do not show response to d-arabinose without the accompanying mutations. Combinations of mutations cooperatively couple molecular recognition to transcriptional activation, demonstrating the complexity of the AraC regulatory switch and the power of combinatorial protein design to alter effector specificity while maintaining regulatory function. PMID:20014443

  19. POST-OPERATIONAL TREATMENT OF RESIDUAL NA COOLLANT IN EBR-2 USING CARBONATION

    SciTech Connect

    Sherman, S.; Knight, C.

    2011-03-08

    safety standpoint, the inventory of residual sodium in these systems was greatly reduced by using the carbonation process. From a regulatory standpoint, the process was not able to achieve deactivation of all residual sodium, and other more aggressive measures will be needed if the remaining residual sodium must also be deactivated to meet the requirements of the existing environmental permit. This chapter provides a project history and technical summary of the carbonation of EBR-II residual sodium. Options for future treatment are also discussed.

  20. CONDORR--CONstrained Dynamics of Rigid Residues: a molecular dynamics program for constrained molecules.

    PubMed

    York, William S; Yi, Xiaobing

    2004-08-01

    A computer program CONDORR (CONstrained Dynamics of Rigid Residues) was developed for molecular dynamics simulations of large and/or constrained molecular systems, particularly carbohydrates. CONDORR efficiently calculates molecular trajectories on the basis of 2D or 3D potential energy maps, and can generate such maps based on a simple force field. The simulations involve three translational and three rotational degrees of freedom for each rigid, asymmetrical residue in the model. Total energy and angular momentum are conserved when no stochastic or external forces are applied to the model, if the time step is kept sufficiently short. Application of Langevin dynamics allows longer time steps, providing efficient exploration of conformational space. The utility of CONDORR was demonstrated by application to a constrained polysaccharide model and to the calculation of residual dipolar couplings for a disaccharide. [Figure: see text]. Molecular models (bottom) are created by cloning rigid residue archetypes (top) and joining them together. As defined here, the archetypes AX, HM and BG respectively correspond to an alpha-D-Xyl p residue, a hydroxymethyl group, and a beta-D-Glc p residue lacking O6, H6a and H6b. Each archetype contains atoms (indicated by boxes) that can be shared with other archetypes to form a linked structure. For example, the glycosidic link between the two D-Glc p residues is established by specifying that O1 of the nonreducing beta-D-Glc p (BG) residue (2) is identical to O4 of the reducing Glc p (BG) residue (1). The coordinates of the two residues are adjusted so as to superimpose these two (nominally distinct) atoms. Flexible hydroxymethyl (HM) groups (3 and 4) are treated as separate residues, and the torsional angles (normally indicated by the symbol omega) that define their geometric relationships to the pyranosyl rings of the BG residues are specified as psi3 and psi4, respectively. The torsional angles phi3 and phi4, defined solely to