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Sample records for africanus ferredoxin iii

  1. [3Fe-4S] <--> [4Fe-4S] cluster interconversion in Desulfovibrio africanus ferredoxin III: properties of an Asp14 --> Cys mutant.

    PubMed Central

    Busch, J L; Breton, J L; Bartlett, B M; Armstrong, F A; James, R; Thomson, A J

    1997-01-01

    The 8Fe ferredoxin III from Desulfovibrio africanus is a monomeric protein which contains two [4Fe-4S]2+/1+ clusters, one of which is labile and can readily and reversibly lose one Fe under oxidative conditions to yield a [3Fe-4S]1+/0 cluster. This 4Fe cluster has an S = 3/2 ground sping state insteaed of S = 1/2 in the reduced +1 state [George, Armstrong, Hatchikian and Thomson (1989) Biochem. J. 264, 275-284]. The co-ordination to this cluster is unusual in that an aspartate (Asp14, D14, is found where a cysteine residue normally occurs. Using a mutant protein obtained from the overexpression in Escherichia coli of a synthetic gene in which Asp14, the putative ligand to the removable Fe, has been changed to Cys, we have studied the cluster interconversion properties of the labile cluster. Analysis by EPR and magnetic-circular-dichroism spectroscopies showed that the Asp14 --> Cys (D14C) mutant contains two [4Fe-4S]2+/1+ clusters, both with S = 1/2 in the reduced state. Also, unlike in native 8Fe D. africanus ferredoxin III, the 4Fe <--> 3Fe cluster interconversion reaction was found to be sluggish and did not go to completion. It is inferred that the reversibility of the reaction in the native protein is due to the presence of the aspartate residue at position 14 and that this residue might protect the [3Fe-4S] cluster from further degradation. PMID:9173907

  2. [3Fe-4S] <--> [4Fe-4S] cluster interconversion in Desulfovibrio africanus ferredoxin III: properties of an Asp14 --> Cys mutant.

    PubMed

    Busch, J L; Breton, J L; Bartlett, B M; Armstrong, F A; James, R; Thomson, A J

    1997-04-01

    The 8Fe ferredoxin III from Desulfovibrio africanus is a monomeric protein which contains two [4Fe-4S]2+/1+ clusters, one of which is labile and can readily and reversibly lose one Fe under oxidative conditions to yield a [3Fe-4S]1+/0 cluster. This 4Fe cluster has an S = 3/2 ground sping state insteaed of S = 1/2 in the reduced +1 state [George, Armstrong, Hatchikian and Thomson (1989) Biochem. J. 264, 275-284]. The co-ordination to this cluster is unusual in that an aspartate (Asp14, D14, is found where a cysteine residue normally occurs. Using a mutant protein obtained from the overexpression in Escherichia coli of a synthetic gene in which Asp14, the putative ligand to the removable Fe, has been changed to Cys, we have studied the cluster interconversion properties of the labile cluster. Analysis by EPR and magnetic-circular-dichroism spectroscopies showed that the Asp14 --> Cys (D14C) mutant contains two [4Fe-4S]2+/1+ clusters, both with S = 1/2 in the reduced state. Also, unlike in native 8Fe D. africanus ferredoxin III, the 4Fe <--> 3Fe cluster interconversion reaction was found to be sluggish and did not go to completion. It is inferred that the reversibility of the reaction in the native protein is due to the presence of the aspartate residue at position 14 and that this residue might protect the [3Fe-4S] cluster from further degradation.

  3. Crystallization and preliminary crystallographic analysis of the pyruvate-ferredoxin oxidoreductase from Desulfovibrio africanus.

    PubMed

    Pieulle, L; Chabrière, E; Hatchikian, C; Fontecilla-Camps, J C; Charon, M H

    1999-01-01

    For the first time, crystals of a pyruvate-ferredoxin oxidoreductase (PFOR) suitable for X-ray analysis have been obtained. This enzyme catalyzes, in anaerobic organisms, the crucial energy-yielding reaction of pyruvate decarboxylation to acetylCoA. Polyethylene glycol and divalent metal cations have been used to crystallize the PFOR from the sulfate-reducing bacterium Desulfovibrio africanus. Two different orthorhombic (P212121 ) crystal forms have been grown with unit-cell dimensions a = 86.1, b = 146.7, c = 212.5 A and a = 84.8, b = 144.9, c = 203.0 A. Both crystals diffract to 2.3 A resolution using synchrotron radiation.

  4. A Ferredoxin Disulfide Reductase Delivers Electrons to the Methanosarcina barkeri Class III Ribonucleotide Reductase

    PubMed Central

    2015-01-01

    Two subtypes of class III anaerobic ribonucleotide reductases (RNRs) studied so far couple the reduction of ribonucleotides to the oxidation of formate, or the oxidation of NADPH via thioredoxin and thioredoxin reductase. Certain methanogenic archaea contain a phylogenetically distinct third subtype of class III RNR, with distinct active-site residues. Here we report the cloning and recombinant expression of the Methanosarcina barkeri class III RNR and show that the electrons required for ribonucleotide reduction can be delivered by a [4Fe-4S] protein ferredoxin disulfide reductase, and a conserved thioredoxin-like protein NrdH present in the RNR operon. The diversity of class III RNRs reflects the diversity of electron carriers used in anaerobic metabolism. PMID:26536144

  5. Ferredoxin and ferredoxin-NADP reductase from photosynthetic and nonphotosynthetic tissues of tomato

    NASA Technical Reports Server (NTRS)

    Green, L. S.; Yee, B. C.; Buchanan, B. B.; Kamide, K.; Sanada, Y.; Wada, K.

    1991-01-01

    Ferredoxin and ferredoxin-NADP+ oxidoreductase (FNR) were purified from leaves, roots, and red and green pericarp of tomato (Lycopersicon esculentum, cv VFNT and cv Momotaro). Four different ferredoxins were identified on the basis of N-terminal amino acid sequence and charge. Ferredoxins I and II were the most prevalent forms in leaves and green pericarp, and ferredoxin III was the most prevalent in roots. Red pericarp of the VFNT cv yielded variable amounts of ferredoxins II and III plus a unique form, ferredoxin IV. Red pericarp of the Momotaro cv contained ferredoxins I, II, and IV. This represents the first demonstration of ferredoxin in a chromoplast-containing tissue. There were no major differences among the tomato ferredoxins in absorption spectrum or cytochrome c reduction activity. Two forms of FNR were present in tomato as judged by anion exchange chromatography and by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. FNR II had a lower apparent relative molecular weight, a slightly altered absorption spectrum, and a lower specific activity for cytochrome c reduction than FNR I. FNR II could be a partially degraded form of FNR I. The FNRs from the different tissues of tomato plants all showed diaphorase activity, with FNR II being more active than FNR I. The presence of ferredoxin and FNR in heterotrophic tissues of tomato is consistent with the existence of a nonphotosynthetic ferredoxin/FNR redox pathway to support the function of ferredoxin-dependent enzymes.

  6. Ferredoxin and ferredoxin-NADP reductase from photosynthetic and nonphotosynthetic tissues of tomato.

    PubMed

    Green, L S; Yee, B C; Buchanan, B B; Kamide, K; Sanada, Y; Wada, K

    1991-01-01

    Ferredoxin and ferredoxin-NADP+ oxidoreductase (FNR) were purified from leaves, roots, and red and green pericarp of tomato (Lycopersicon esculentum, cv VFNT and cv Momotaro). Four different ferredoxins were identified on the basis of N-terminal amino acid sequence and charge. Ferredoxins I and II were the most prevalent forms in leaves and green pericarp, and ferredoxin III was the most prevalent in roots. Red pericarp of the VFNT cv yielded variable amounts of ferredoxins II and III plus a unique form, ferredoxin IV. Red pericarp of the Momotaro cv contained ferredoxins I, II, and IV. This represents the first demonstration of ferredoxin in a chromoplast-containing tissue. There were no major differences among the tomato ferredoxins in absorption spectrum or cytochrome c reduction activity. Two forms of FNR were present in tomato as judged by anion exchange chromatography and by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. FNR II had a lower apparent relative molecular weight, a slightly altered absorption spectrum, and a lower specific activity for cytochrome c reduction than FNR I. FNR II could be a partially degraded form of FNR I. The FNRs from the different tissues of tomato plants all showed diaphorase activity, with FNR II being more active than FNR I. The presence of ferredoxin and FNR in heterotrophic tissues of tomato is consistent with the existence of a nonphotosynthetic ferredoxin/FNR redox pathway to support the function of ferredoxin-dependent enzymes.

  7. Metacarpal proportions in Australopithecus africanus.

    PubMed

    Green, David J; Gordon, Adam D

    2008-05-01

    Recent work has shown that, despite being craniodentally more derived, Australopithecus africanus had more apelike limb-size proportions than A. afarensis. Here, we test whether the A. africanus hand, as judged by metacarpal shaft and articular proportions, was similarly apelike. More specifically, did A. africanus have a short and narrow first metacarpal (MC1) relative to the other metacarpals? Proportions of both MC breadth and length were considered: the geometric mean (GM) of articular and midshaft measurements of MC1 breadth was compared to those of MC2-4, and MC1 length was compared to MC3 length individually and also to the GM of MC2 and 3 lengths. To compare the extant hominoid sample with an incomplete A. africanus fossil record (11 attributed metacarpals), a resampling procedure imposed sampling constraints on the comparative groups that produced composite intrahand ratios. Resampled ratios in the extant sample are not significantly different from actual ratios based on associated elements, demonstrating the methodological appropriateness of this technique. Australopithecus africanus metacarpals do not differ significantly from the great apes in the comparison of breadth ratios but are significantly greater than chimpanzees and orangutans in both measures of relative length. Conversely, A. africanus has a significantly smaller breadth ratio than modern humans, but does not significantly differ from this group in either measure of relative length. We conclude that the first metacarpals of A. africanus are more apelike in relative breadth while also being more humanlike in relative length, a finding consistent with previous work on A. afarensis hand proportions. This configuration would have likely promoted a high degree of manipulative dexterity, but the relatively slender, apelike first metacarpal suggests that A. africanus did not place the same mechanical demands on the thumb as more recent, stone-tool-producing hominins.

  8. Visualisation of plastids in endosperm, pollen and roots of transgenic wheat expressing modified GFP fused to transit peptides from wheat SSU RubisCO, rice FtsZ and maize ferredoxin III proteins.

    PubMed

    Primavesi, Lucia F; Wu, Huixia; Mudd, Elisabeth A; Day, Anil; Jones, Huw D

    2008-08-01

    The ability to target marker proteins to specific subcellular compartments is a powerful research tool to study the structure and development of organelles. Here transit sequences from nuclear-encoded, plastid proteins, namely rice FtsZ, maize non-photosynthetic ferredoxin III (FdIII) and the small subunit of RubisCO were used to target a modified synthetic GFP (S65G, S72A) to plastids. The localisations of the fusion proteins expressed in transgenic wheat plants and under the control of the rice actin promoter were compared to an untargeted GFP control. GFP fluorescence was localised to non-green plastids in pollen, roots and seed endosperm and detected in isolated leaf chloroplasts using a GFP-specific antibody. Transit peptides appeared to influence the relative fluorescence intensities of plastids in different tissues. This is consistent with differential targeting and/or turnover of GFP fusion proteins in different plastid types. Replacement of GFP sequences with alternative coding regions enables immediate applications of our vectors for academic research and commercial applications.

  9. New perspectives on bacterial ferredoxin evolution

    NASA Technical Reports Server (NTRS)

    George, D. G.; Hunt, L. T.; Yeh, L.-S. L.; Barker, W. C.

    1985-01-01

    Ferredoxins are low-molecular-weight, nonheme, iron proteins which function as electron carriers in a wide variety of electron transport chains. Howard et al. (1983) have suggested that the amino end of Azotobacter vinelandii ferredoxin shows a greater similarity to the carboxyl end of ferredoxin from Chromatium vinosum and that their half-chain sequences are homologous when the half-chains of either species are considered in inverse order. Examination of this proposition has made it necessary to reevaluate previous conclusions concerning the evolution of bacterial ferredoxin. Attention is given to the properties of the bacterial ferredoxin sequences, and the evolution of the bacterial ferredoxins.

  10. The capitate of Australopithecus afarensis and A. africanus.

    PubMed

    McHenry, H M

    1983-10-01

    The capitates of Australopithecus afarensis (AL 288-lw and AL 333-40) and A. africanus (TM 1526) have the identical combination of modern pongid, modern hominid, and unique characteristics. These traits include the combination of a length that is proximodistally shortened (Homo sapiens-like), a facet for the second metacarpal that is distolaterally facing (unique), the reduced styloid process on the third metacarpal (pongidlike), a dorsally placed trapezoid facet (pongidlike), mediolaterally constricted metacarpal III facet (pongidlike), a prominent palmar beak (pongidlike), a single elongated facet for the second metacarpal (H. sapiens-like), a waisted neck (pongidlike), and a reduced amount of "cupping" in the third metacarpal facet (H. sapiens-like). In overall shape the bones are more like H. sapiens than other extant hominids, although they are uniquely different. The two A. afarensis capitates provide no evidence that there are two postcranial morphotypes at Hadar. Available evidence shows that A. afarensis and A. africanus are strikingly similar postcranially. The morphological differences between the capitate of Australopithecus and H. sapiens may relate to the retention of climbing ability and an absence of certain grip capabilities in these early hominids.

  11. Ferredoxin-linked chloroplast enzymes. Progress report

    SciTech Connect

    1993-12-31

    This report summarizes research on ferredoxin:NADP{sup +} oxidoreductase and ferredoxin:thioredoxin reductase. One of the primary goals of the original proposal was to map the ferredoxin-binding sites on three soluble enzymes that are located in spinach chloroplasts and utilize ferredoxin as an electron donor:Ferredoxin:NADP{sup +} oxidoreductase (FNR); ferredoxin:thioredoxin reductase (FTR) and glutamate synthase. As the availability of amino acid sequences for the enzymes are important in such studies, it was proposed that the amino acid sequence of glutamate synthase be determined. The amino acid sequences of FNR, FTR and ferredoxin are already known. An aim related to elucidating the binding sites on these enzymes for ferredoxin was to determine whether there is a common site on ferredoxin involved in binding to all of these ferredoxin-dependent chloroplast enzymes and, if so, to map it. One additional aim was to characterize thioredoxin binding by FTR and determine whether the same site on FTR is involved in binding both ferredoxin and thioredoxin. Considerable progress has been made on most of these original projects, although work conducted on FTR is still in its preliminary stages.

  12. Energy conservation via electron bifurcating ferredoxin reduction and proton/Na(+) translocating ferredoxin oxidation.

    PubMed

    Buckel, Wolfgang; Thauer, Rudolf K

    2013-02-01

    The review describes four flavin-containing cytoplasmatic multienzyme complexes from anaerobic bacteria and archaea that catalyze the reduction of the low potential ferredoxin by electron donors with higher potentials, such as NAD(P)H or H(2) at ≤ 100 kPa. These endergonic reactions are driven by concomitant oxidation of the same donor with higher potential acceptors such as crotonyl-CoA, NAD(+) or heterodisulfide (CoM-S-S-CoB). The process called flavin-based electron bifurcation (FBEB) can be regarded as a third mode of energy conservation in addition to substrate level phosphorylation (SLP) and electron transport phosphorylation (ETP). FBEB has been detected in the clostridial butyryl-CoA dehydrogenase/electron transferring flavoprotein complex (BcdA-EtfBC), the multisubunit [FeFe]hydrogenase from Thermotoga maritima (HydABC) and from acetogenic bacteria, the [NiFe]hydrogenase/heterodisulfide reductase (MvhADG-HdrABC) from methanogenic archaea, and the transhydrogenase (NfnAB) from many Gram positive and Gram negative bacteria and from anaerobic archaea. The Bcd/EtfBC complex that catalyzes electron bifurcation from NADH to the low potential ferredoxin and to the high potential crotonyl-CoA has already been studied in some detail. The bifurcating protein most likely is EtfBC, which in each subunit (βγ) contains one FAD. In analogy to the bifurcating complex III of the mitochondrial respiratory chain and with the help of the structure of the human ETF, we propose a conformational change by which γ-FADH(-) in EtfBC approaches β-FAD to enable the bifurcating one-electron transfer. The ferredoxin reduced in one of the four electron bifurcating reactions can regenerate H(2) or NADPH, reduce CO(2) in acetogenic bacteria and methanogenic archaea, or is converted to ΔμH(+)/Na(+) by the membrane-associated enzyme complexes Rnf and Ech, whereby NADH and H(2) are recycled, respectively. The mainly bacterial Rnf complexes couple ferredoxin oxidation by NAD(+) with

  13. Crystal structures of archaeal 2-oxoacid:ferredoxin oxidoreductases from Sulfolobus tokodaii

    PubMed Central

    Yan, Zhen; Maruyama, Akane; Arakawa, Takatoshi; Fushinobu, Shinya; Wakagi, Takayoshi

    2016-01-01

    As the first three-dimensional structure of the two-subunit type 2-oxoacid:ferredoxin oxidoreductases (OFOR) from archaea, we solved the crystal structures of STK_23000/STK_22980 (StOFOR1) and STK_24350/STK_24330 (StOFOR2) from Sulfolobus tokodaii. They showed similar overall structures, consisting of two a- and b-subunit heterodimers containing thiamin pyrophosphate (TPP) cofactor and [4Fe-4S] cluster, but lack an intramolecular ferredoxin domain. Unlike other OFORs, StOFORs can utilize both pyruvate and 2-oxoglutarate, playing a key role in the central metabolism. In the structure of StOFOR2 in unreacted pyruvate complex form, carboxylate group of pyruvate is recognized by Arg344 and Thr257 from the a-subunit, which are conserved in pyruvate:ferredoxin oxidoreductase from Desulfovbrio africanus (DaPFOR). In the structure of StOFOR1 co-crystallized with 2-oxobutyrate, electron density corresponding to a 1-hydroxypropyl group (post-decarboxylation state) was observed at the thiazole ring of TPP. The binding pockets of the StOFORs surrounding the methyl or propyl group of the ligands are wider than that of DaPFOR. Mutational analyses indicated that several residues were responsible for the broad 2-oxoacid specificity of StOFORs. We also constructed a possible complex structural model by placing a Zn2+-containing dicluster ferredoxin of S. tokodaii into the large pocket of StOFOR2, providing insight into the electron transfer between the two redox proteins. PMID:27619895

  14. (The interaction of ferredoxin:NADP sup + oxidoreductase and ferredoxin:thioredoxin reductase with substrates)

    SciTech Connect

    Not Available

    1992-01-01

    We seek to map the ferredoxin-binding sites on three soluble enzymes located in spinach chloroplasts which utilize ferredoxin as an electron donor:Ferredoxin:NADP{sup +}oxidoreductase (FNR); ferredoxin:thioredoxin reductase (FTR) and glutamate synthase. As the availability of amino acid sequences for the enzymes are important in such studies, that the amino acid sequence of glutamate synthase needs be determined, the amino acid sequences of FNR, FTR and ferredoxin are already known. Related to an aim elucidate the binding sites for ferredoxin to determine whether there is a common binding site on all of these ferredoxin-dependent chloroplast enzymes and, if so, to map it. Additionally thioredoxin binding by FTR needs be determine to resolve whether the same site on FTR is involved in binding both ferredoxin and thioredoxin. Considerable progress is reported on the prosthetic groups of glutamate synthase, in establishing the role of arginine and lysine residues in ferredoxin binding by, ferredoxin:nitrite oxidoreductase nitrite reductase, labelling carboxyl groups on ferredoxin with taurine and labelling lysine residues biotinylation, and low potential heme proteins have been isolated and characterized from a non-photosynthetic plant tissue. Although the monoclonal antibodies raised against FNR turned out not to be useful for mapping the FNR/ferredoxin or FNR/NADPinteraction domains, good progress has been made on mapping the FNR/ferredoxin interaction domains by an alternative technique. The techniques developed for differential chemical modification of these two proteins - taurine modification of aspartate and glutamate residues and biotin modification of lysine residues - should be useful for mapping the interaction domains of many proteins that associate through electrostatic interactions.

  15. Limb-size proportions in Australopithecus afarensis and Australopithecus africanus.

    PubMed

    Green, David J; Gordon, Adam D; Richmond, Brian G

    2007-02-01

    Previous analyses have suggested that Australopithecus africanus possessed more apelike limb proportions than Australopithecus afarensis. However, due to the errors involved in estimating limb length and body size, support for this conclusion has been limited. In this study, we use a new Monte Carlo method to (1) test the hypothesis that A. africanus had greater upper:lower limb-size proportions than A. afarensis and (2) assess the statistical significance of interspecific differences among these taxa, extant apes, and humans. Our Monte Carlo method imposes sampling constraints that reduce extant ape and human postcranial measurements to sample sizes comparable to the fossil samples. Next, composite ratios of fore- and hindlimb geometric means are calculated for resampled measurements from the fossils and comparative taxa. Mean composite ratios are statistically indistinguishable (alpha=0.05) from the actual ratios of extant individuals, indicating that this method conserves each sample's central tendency. When applied to the fossil samples, upper:lower limb-size proportions in A. afarensis are similar to those of humans (p=0.878) and are significantly different from all great ape proportions (p< or =0.034), while Australopithecus africanus is more similar to the apes (p> or =0.180) and significantly different from humans and A. afarensis (p< or =0.031). These results strongly support the hypothesis that A. africanus possessed more apelike limb-size proportions than A. afarensis, suggesting that A. africanus either evolved from a more postcranially primitive ancestor than A. afarensis or that the more apelike limb-size proportions of A. africanus were secondarily derived from an A. afarensis-like ancestor. Among the extant taxa, limb-size proportions correspond with observed levels of forelimb- and hindlimb-dominated positional behaviors. In conjunction with detailed anatomical features linked to arboreality, these results suggest that arboreal posture and

  16. Sexual dimorphism in the face of Australopithecus africanus.

    PubMed

    Lockwood, C A

    1999-01-01

    Recently discovered crania of Australopithecus africanus from Sterkfontein Member 4 and Makapansgat enlarge the size range of the species and encourage a reappraisal of both the degree and pattern of sexual dimorphism. Resampling methodology (bootstrapping) is used here to establish that A. africanus has a greater craniofacial size range than chimpanzees or modern humans, a range which is best attributed to a moderately high degree of sexual dimorphism. Compared to other fossil hominins, this variation is similar to that of Homo habilis (sensu lato) but less than that of A. boisei. The finding of moderately high dimorphism is corroborated by a CV-based estimate and ratios between those specimens considered to be male and those considered to be female. Inferences about the pattern of craniofacial dimorphism in the A. africanus face currently rely on the relationship of morphology and size. Larger specimens, particularly Stw 505, show prominent superciliary eminences and glabellar regions, but in features related in part to canine size, such as the curvature of the infraorbital surface, large and small specimens of A. africanus are similar. In this respect, the pattern resembles that of modern humans more so than chimpanzees or lowland gorillas. A. africanus may also show novel patterns of sexual dimorphism when compared to extant hominines, such as in the form of the anterior pillar. However, males of the species do not exhibit characteristics of more derived hominins, such as A. robustus.

  17. Role of Morphological Growth State and Gene Expression in Desulfovibrio africanus strain Walvis Bay Mercury Methylation

    SciTech Connect

    Moberly, James G; Miller, Carrie L; Brown, Steven D; Biswas, Abir; Brandt, Craig C; Palumbo, Anthony Vito; Elias, Dwayne A

    2012-01-01

    The biogeochemical transformations of mercury are a complex process, with the production of methylmercury, a potent human neurotoxin, repeatedly demonstrated in sulfate- and Fe(III)- reducing as well as methanogenic bacteria. However, little is known regarding the morphology, genes or proteins involved in methylmercury generation. Desulfovibrio africanus strain Walvis Bay is a Hg-methylating -proteobacterium with a sequenced genome and has unusual pleomorphic forms. In this study, a relationship between the pleomorphism and Hg methylation was investigated. Proportional increases in the sigmoidal (regular) cell form corresponded with increased net MeHg production, but decreased when the pinched cocci (persister) form became the major morphotype. D. africanus microarrays indicated that the ferrous iron transport genes (feoAB), as well as ribosomal genes and several genes whose products are predicted to have metal binding domains (CxxC), were up-regulated during exposure to Hg in the exponential phase. While no specific methylation pathways were identified, the finding that Hg may interfere with iron transport and the correlation of growth-phase dependent morphology with MeHg production are notable. The identification of these relationships between differential gene expression, morphology, and the growth phase dependence of Hg transformations suggests that actively growing cells are primarily responsible for methylation, and so areas with ample carbon and electron-acceptor concentrations may also generate a higher proportion of methylmercury than more oligotrophic environments. The observation of increased iron transporter expression also suggests that Hg methylation may interfere with iron biogeochemical cycles.

  18. Isolation and characterization of an Fe,-S8 ferredoxin (ferredoxin II) from Clostridium thermoaceticum.

    PubMed Central

    Elliott, J I; Ljungdahl, L G

    1982-01-01

    A second ferredoxin protein was isolated from the thermophilic anaerobic bacterium Clostridium thermoaceticum and termed ferredoxin II. This ferredoxin was found to contain 7.9 +/- 0.3 iron atoms and 7.4 +/- 0.4 acid-labile sulfur atoms per mol of protein. Extrusion studies of the iron-sulfur centers showed the presence of two [Fe4-S4] centers per mol of protein and accounted for all of the iron present. The absorption spectrum was characterized by maxima at 390 nm (epsilon 390 = 30,400 M-1cm-1) and 280 nm (epsilon 280 = 41.400 M-1 cm-1) and by a shoulder at 300 nm. The ration of the absorbance of the pure protein at 390 nm to the absorbance at 280 nm was 0.74. Electron paramagnetic resonance data showed a weak signal in the oxidized state, and the reduced ferredoxin exhibited a spectrum typical of [Fe4-S4] clusters. Double integration of the reduced spectra showed that two electrons were necessary for the complete reduction of ferredoxin II. Amino histidine, and 1 arginine, and a molecular weight of 6,748 for the native protein. The ferredoxin is stable under anaerobic conditions for 60 min at 70 degrees C. The average oxidation-reduction potential for the two [Fe4-S4] centers was measured as -365 mV. PMID:6282807

  19. Spinach ferredoxin i: overproduction in Escherichia coli and purification.

    PubMed

    Piubelli, L; Aliverti, A; Bellintani, F; Zanetti, G

    1995-06-01

    Ferredoxin I is the most abundant form of photosynthetic-type ferredoxin present in spinach chloroplasts. A cDNA clone encoding the precursor of spinach ferredoxin I has been engineered to synthesize the mature form of the plant protein in Escherichia coli. Among several different plasmid constructions, the expression system based on phage T7 promoter (vector pET-11d) was found to be the most efficient for spinach ferredoxin overproduction. Upon induction, ferredoxin I accounted for about 2.5% of soluble E. coli protein. A rapid procedure for the purification of the recombinant protein, which yielded at least 1 mg of homogeneous ferredoxin I per gram of cells (fresh wt), was developed. The recombinant protein was found to be identical to ferredoxin I isolated from spinach, both by mass spectrometry analysis and by N-terminal protein sequencing, indicating in vivo removal of the N-terminal methionine. Ferredoxin I was synthesized as the holoprotein, correctly assembled with the [2Fe-2S] cluster as judged by its absorption spectrum, and was fully active in the assay with its physiological partner (ferredoxin-NADP+ reductase). The expression system described here is amenable to the structure-function relationship study of spinach ferredoxin I through site-directed mutagenesis and NMR spectroscopy.

  20. Microwear, mechanics and the feeding adaptations of Australopithecus africanus.

    PubMed

    Strait, David S; Weber, Gerhard W; Constantino, Paul; Lucas, Peter W; Richmond, Brian G; Spencer, Mark A; Dechow, Paul C; Ross, Callum F; Grosse, Ian R; Wright, Barth W; Wood, Bernard A; Wang, Qian; Byron, Craig; Slice, Dennis E

    2012-01-01

    Recent studies of dental microwear and craniofacial mechanics have yielded contradictory interpretations regarding the feeding ecology and adaptations of Australopithecus africanus. As part of this debate, the methods used in the mechanical studies have been criticized. In particular, it has been claimed that finite element analysis has been poorly applied to this research question. This paper responds to some of these mechanical criticisms, highlights limitations of dental microwear analysis, and identifies avenues of future research.

  1. Reproduction and Damage Potential of Five Geographical Ditylenchus africanus Populations on Peanut

    PubMed Central

    Steenkamp, Sonia; De Waele, Dirk; McDonald, Alexander

    2016-01-01

    Ditylenchus africanus affects peanut quality, which leads to downgrading of consignments and economic losses for producers. This nematode is difficult to control and host-plant resistance may be the most effective way to control it. Recently, the peanut breeding line PC254K1 has been identified as resistant to a D. africanus population from Vaalharts and will be included into the peanut breeding program. The objectives of our study were to compare the reproduction potential of D. africanus geographic populations from five different areas in the peanut production area of South Africa and to assess whether PC254K1 is resistant to all five D. africanus populations. Reproduction of the D. africanus populations was evaluated on peanut callus in growth cabinets at 21°C, 28°C, and 35°C. The peanut cv. Sellie was included in the study as the D. africanus-susceptible reference genotype in the greenhouse and microplots. Reproduction potential of all five of the D. africanus populations was similar. Resistance of PC254K1 was confirmed to all five D. africanus populations. The resistance trait of a D. africanus-resistant cultivar developed from PC254K1 should, therefore, be sustainable over the five localities tested during this study. PMID:27418699

  2. [The interaction of ferredoxin:NADP{sup +} oxidoreductase and ferredoxin:thioredoxin reductase with substrates]. Progress report

    SciTech Connect

    Not Available

    1992-09-01

    We seek to map the ferredoxin-binding sites on three soluble enzymes located in spinach chloroplasts which utilize ferredoxin as an electron donor:Ferredoxin:NADP{sup +}oxidoreductase (FNR); ferredoxin:thioredoxin reductase (FTR) and glutamate synthase. As the availability of amino acid sequences for the enzymes are important in such studies, that the amino acid sequence of glutamate synthase needs be determined, the amino acid sequences of FNR, FTR and ferredoxin are already known. Related to an aim elucidate the binding sites for ferredoxin to determine whether there is a common binding site on all of these ferredoxin-dependent chloroplast enzymes and, if so, to map it. Additionally thioredoxin binding by FTR needs be determine to resolve whether the same site on FTR is involved in binding both ferredoxin and thioredoxin. Considerable progress is reported on the prosthetic groups of glutamate synthase, in establishing the role of arginine and lysine residues in ferredoxin binding by, ferredoxin:nitrite oxidoreductase nitrite reductase, labelling carboxyl groups on ferredoxin with taurine and labelling lysine residues biotinylation, and low potential heme proteins have been isolated and characterized from a non-photosynthetic plant tissue. Although the monoclonal antibodies raised against FNR turned out not to be useful for mapping the FNR/ferredoxin or FNR/NADPinteraction domains, good progress has been made on mapping the FNR/ferredoxin interaction domains by an alternative technique. The techniques developed for differential chemical modification of these two proteins - taurine modification of aspartate and glutamate residues and biotin modification of lysine residues - should be useful for mapping the interaction domains of many proteins that associate through electrostatic interactions.

  3. ROLE OF FERREDOXIN IN THE METABOLISM OF MOLECULAR HYDROGEN.

    PubMed

    VALENTINE, R C; WOLFE, R S

    1963-05-01

    Valentine, R. C. (University of Illinois, Urbana) and R. S. Wolfe. Role of ferredoxin in the metabolism of molecular hydrogen. J. Bacteriol. 85:1114-1120. 1963.-The metabolism of molecular hydrogen by Clostridium pasteurianum, Micrococcus lactilyticus (Veillonella alcalescens), and several other anaerobic bacteria was studied. Oxidation of hydrogen, using several electron-accepting substrates including triphosphopyridine nucleotide, uric acid, xanthine, nitrite, and hydroxylamine, required ferredoxin in conjunction with hydrogenase. Evolution of hydrogen from pyruvate, alpha-ketoglutarate, hypoxanthine, and dithionite was mediated by ferredoxin. On the basis of these findings, a unitary hypothesis for biological hydrogen evolution is proposed in which ferredoxin plays a key role.

  4. Sequence and expression of ferredoxin mRNA in barley

    SciTech Connect

    Zielinski, R.; Funder, P.M.; Ling, V. )

    1990-05-01

    We have isolated and structurally characterized a full-length cDNA clone encoding ferredoxin from a {lambda}gt10 cDNA library prepared from barley leaf mRNA. The ferredoxin clone (pBFD-1) was fused head-to-head with a partial-length cDNA clone encoding calmodulin, and was fortuitously isolated by screening the library with a calmodulin-specific oligonucleotide probe. The mRNA sequence from which pBFD-1 was derived is expressed exclusively in the leaf tissues of 7-d old barley seedlings. Barley pre-ferredoxin has a predicted size of 15.3 kDal, of which 4.6 kDal are accounted for by the transit peptide. The polypeptide encoded by pBFD-1 is identical to wheat ferredoxin, and shares slightly more amino acid sequence similarity with spinach ferredoxin I than with ferredoxin II. Ferredoxin mRNA levels are rapidly increased 10-fold by white light in etiolated barley leaves.

  5. Human evolution. Human-like hand use in Australopithecus africanus.

    PubMed

    Skinner, Matthew M; Stephens, Nicholas B; Tsegai, Zewdi J; Foote, Alexandra C; Nguyen, N Huynh; Gross, Thomas; Pahr, Dieter H; Hublin, Jean-Jacques; Kivell, Tracy L

    2015-01-23

    The distinctly human ability for forceful precision and power "squeeze" gripping is linked to two key evolutionary transitions in hand use: a reduction in arboreal climbing and the manufacture and use of tools. However, it is unclear when these locomotory and manipulative transitions occurred. Here we show that Australopithecus africanus (~3 to 2 million years ago) and several Pleistocene hominins, traditionally considered not to have engaged in habitual tool manufacture, have a human-like trabecular bone pattern in the metacarpals consistent with forceful opposition of the thumb and fingers typically adopted during tool use. These results support archaeological evidence for stone tool use in australopiths and provide morphological evidence that Pliocene hominins achieved human-like hand postures much earlier and more frequently than previously considered.

  6. Effect of Plant Age and Longidorus africanus on the Growth of Lettuce and Carrot

    PubMed Central

    Huang, Xiang; Ploeg, Antoon T.

    2001-01-01

    Needle nematodes, Longidorus africanus, were added to carrot and lettuce seedlings in a range of inoculum levels and at various times after seeding. The effects of inoculum density and delayed inoculation on plant growth were analyzed according to Seinhorst's damage function. Growth of both lettuce and carrot was severely affected by L. africanus, but delaying nematode inoculation until 10 days after seeding significantly increased estimated minimum yields in both crop species. Tolerance levels of lettuce and carrot for L. africanus were approximately 10 times lower than those reported for other longidorid-crop associations. We conclude that methods aimed at avoiding immediate exposure of germinating seeds to L. africanus may significantly reduce crop damage. PMID:19266010

  7. Aedes (Stegomyia) Corneti, A New Species of the Africanus Subgroup (Diptera: Culicidae)

    DTIC Science & Technology

    1986-10-14

    virus , chikungunya, Zika and Bouboui viruses have been isolated from Ae. africanus and Ae. opok in the Central African Republic (Germain et al., 1978...and chikungunya, Zika and dengue 2 viruses have been isolated from Ae. Zuteocephalus in Senegal (Comet et al., 1979). Members of the africanus... Zika virus (1). Isolations and serological specificity. Trans. R. Sot. Trop. Med. Hyg. 46: 600-6 18. Germain, M., J. P. Eouzan, and L. Ferrara

  8. Comparative studies on two ferredoxins from the cyanobacterium Nostoc strain MAC.

    PubMed

    Hutson, K G; Rogers, L J; Haslett, B G; Boulter, D; Cammack, R

    1978-06-15

    Two ferredoxins were isolated from the cyanobacterium Nostoc strain MAC grown autotrophically in the light or heterotrophically in the dark. In either case approximately three times as much ferredoxin I as ferredoxin II was obtained. Both ferredoxins had absorption maxima at 276, 282 (shoulder), 330, 423 and 465 nm in the oxidized state, and each possessed a single 2 Fe-2S active centre. Their isoelectric points were approx. 3.2. The midpoint redox potentials of the ferredoxins differed markedly; that of ferredoxin I was --350mV and that of ferredoxin II was --445mV, at pH 8.0. The midpoint potential of ferredoxin II was unusual in being pH dependent. Ferredoxin I was most active in supporting NADP+ photoreduction by chloroplasts, whereas ferredoxin II was somewhat more active in pyruvate decarboxylation by the phosphoroclastic system of Clostridum pasteurianum. Though the molecular weights of the ferredoxins determined by ultracentrifugation were the same within experimetnal error, the amino acid compositions showed marked differences. The N-terminal amino acid sequences of ferredoxins I and II were determined by means of an automatic sequencer. There are 11--12 differences between the sequences of the first 32 residues. It appears that the two ferredoxins have evolved separately to fulfil different roles in the organism.

  9. The potential of Cyathus africanus for transformation of terpene substrates.

    PubMed

    McCook, Kayanne P; Chen, Avril R M; Reynolds, William F; Reese, Paul B

    2012-10-01

    The insecticidal sesquiterpenes cadina-4,10(15)-dien-3-one and aromadendr-1(10)-en-9-one were administered to the fungus Cyathus africanus ATCC 35853. Biotransformation of the former produced (4R)-9α-hydroxycadin-10(15)-en-3-one, while the latter gave 2β-hydroxyaromadendr-1(10)-en-9-one, 2α-hydroxyaromadendr-1(10)-en-9-one and 10α-hydroxy-1β,2β-epoxyaromadendran-9-one. The bioconversion of santonin led to the production of two analogues, 11,13-dihydroxysantonin and the hitherto unreported 8α,13-dihydroxysantonin, while cedrol yielded 3β,8β-dihydroxycedrane and 3α,8β-dihydroxycedrane. Stemod-12-ene, a diterpene, was transformed to 2-oxostemar-13-ene, a hitherto unknown analogue with a rearranged carbon framework. When methyl betulonate, a triterpenoid belonging to the lupane family, was supplied to the fungus 18α-ursane and 18α-oleanane derivatives, namely 19β-hydroxy-3-oxo-18α-oleanan-28-oic acid and 19α-hydroxy-3-oxo-18α-ursan-28-oic acids, were generated. There are no previous reports of fungal transformation of a triterpene in which a skeletal rearrangement occurred. All substrate administration experiments were done in the presence of the terpene cyclase inhibitor chlorocholine chloride (CCC), using the single phase - pulse feed method.

  10. Horizontal and Vertical Distribution of Longidorus africanus in a Bermudagrass Field in the Imperial Valley, California

    PubMed Central

    Ploeg, Antoon T.

    1998-01-01

    The horizontal and vertical distribution of the needle nematode Longidorus africanus was studied in a bermudagrass field in the Imperial Valley in southern California. A geostatistical method involving the use of semi-variograms was used to quantify the relationship between sampling distance and variation in L. africanus population levels. Semi-variance between nematode numbers from different samples was very low when samples were taken close together, increased with sampling distances up to ca. 15 m, and fluctuated around a sill value at distances greater than 15 m. At very large sampling distances the semi-variance increased further. It was concluded that patches with fairly similar numbers of L. africanus were elongated and up to 15 m long. Seasonal fluctuations over a 2-year period, in total numbers of L. africanus extracted from three depths, were large and highly correlated with soil temperature. Population densities were greatest during the summer months and lowest during the winter. Averaged over the 2-year period, L. africanus population densities increased with increasing depth. Chances for detecting this nematode are greatest in summer at depths of 60 to 90 cm. PMID:19274252

  11. Heterologous overproduction of 2[4Fe4S]- and [2Fe2S]-type clostridial ferredoxins and [2Fe2S]-type agrobacterial ferredoxin.

    PubMed

    Huang, Haiyan; Hu, Liejie; Yu, Wenjun; Li, Huili; Tao, Fei; Xie, Huijun; Wang, Shuning

    2016-05-01

    Ferredoxins are small, acidic proteins containing iron-sulfur clusters that are widespread in living organisms. They play key roles as electron carriers in various metabolic processes, including respiration, photosynthesis, fermentation, nitrogen fixation, carbon dioxide fixation, and hydrogen production. However, only several kinds of ferredoxins are commercially available now, greatly limiting the investigation of ferredoxin-related enzymes and metabolic processes. Here we describe the heterologous overproduction of 2[4Fe4S]- and [2Fe2S]-type clostridial ferredoxins and [2Fe2S]-type agrobacterial ferredoxin. Adding extra iron and sulfur sources to the medium in combination with using Escherichia coli C41(DE3) harboring pCodonplus and pRKISC plasmids as host greatly enhanced iron-sulfur cluster synthesis in the three ferredoxins. After induction for 12 h in terrific broth and purification by affinity chromatography and anion exchange chromatography, approximately 3.4 mg of streptavidin (Strep)-tagged and 3.7 mg of polyhistidine (His)-tagged clostridial 2[4Fe4S] ferredoxins were obtained from 1 l of culture. Excitingly, after induction for 24 h in terrific broth, around 40 mg of His-tagged clostridial [2Fe2S] and 23 mg of His-tagged agrobacterial [2Fe2S] ferredoxins were purified from 1 l of culture. The recombinant ferredoxins apparently exhibited identical properties and physiological function to native ferredoxins. No negative impact of two different affinity tags on ferredoxin activity was found. In conclusion, we successfully developed a convenient method for heterologous overproduction of the three kinds of ferredoxins with satisfactory yields and activities, which would be very helpful for the ferredoxin-related researches.

  12. Evolution of the acceptor side of photosystem I: ferredoxin, flavodoxin, and ferredoxin-NADP(+) oxidoreductase.

    PubMed

    Pierella Karlusich, Juan José; Carrillo, Néstor

    2017-02-01

    The development of oxygenic photosynthesis by primordial cyanobacteria ~2.7 billion years ago led to major changes in the components and organization of photosynthetic electron transport to cope with the challenges of an oxygen-enriched atmosphere. We review herein, following the seminal contributions as reported by Jaganathan et al. (Functional genomics and evolution of photosynthetic systems, vol 33, advances in photosynthesis and respiration, Springer, Dordrecht, 2012), how these changes affected carriers and enzymes at the acceptor side of photosystem I (PSI): the electron shuttle ferredoxin (Fd), its isofunctional counterpart flavodoxin (Fld), their redox partner ferredoxin-NADP(+) reductase (FNR), and the primary PSI acceptors F x and F A/F B. Protection of the [4Fe-4S] centers of these proteins from oxidative damage was achieved by strengthening binding between the F A/F B polypeptide and the reaction center core containing F x, therefore impairing O2 access to the clusters. Immobilization of F A/F B in the PSI complex led in turn to the recruitment of new soluble electron shuttles. This function was fulfilled by oxygen-insensitive [2Fe-2S] Fd, in which the reactive sulfide atoms of the cluster are shielded from solvent by the polypeptide backbone, and in some algae and cyanobacteria by Fld, which employs a flavin as prosthetic group and is tolerant to oxidants and iron limitation. Tight membrane binding of FNR allowed solid-state electron transfer from PSI bridged by Fd/Fld. Fine tuning of FNR catalytic mechanism led to formidable increases in turnover rates compared with FNRs acting in heterotrophic pathways, favoring Fd/Fld reduction instead of oxygen reduction.

  13. Dental metric assessment of the omo fossils: implications for the phylogenetic position of Australopithecus africanus.

    PubMed

    Hunt, K; Vitzthum, V J

    1986-10-01

    The discovery of Australopithecus afarensis has led to new interpretations of hominid phylogeny, some of which reject A. africanus as an ancestor of Homo. Analysis of buccolingual tooth crown dimensions in australopithecines and Homo species by Johanson and White (Science 202:321-330, 1979) revealed that the South African gracile australopithecines are intermediate in size between Laetoli/hadar hominids and South African robust hominids. Homo, on the other hand, displays dimensions similar to those of A. afarensis and smaller than those of other australopithecines. These authors conclude, therefore, that A. africanus is derived in the direction of A. robustus and is not an ancestor of the Homo clade. However, there is a considerable time gap (ca. 800,000 years) between the Laetoli/Hadar specimens and the earliest Homo specimens; "gracile" hominids from Omo fit into this chronological gap and are from the same geographic area. Because the early specimens at Omo have been designated A. afarensis and the later specimens classified as Homo habilis, Omo offers a unique opportunity to test hypotheses concerning hominid evolution, especially regarding the phylogenetic status of A. africanus. Comparisons of mean cheek teeth breadths disclosed the significant (P less than or equal to 0.05) differences between the Omo sample and the Laetoli/Hadar fossils (P4, M2, and M3), the Homo fossils (P3, P4, M1, M2, and M1), and A. africanus (M3). Of the several possible interpretations of these data, it appears that the high degree of similarity between the Omo sample and the South African gracile australopithecine material warrants considering the two as geographical variants of A. africanus. The geographic, chronologic, and metric attributes of the Omo sample argue for its lineal affinity with A. afarensis and Homo. In conclusion, a consideration of hominid postcanine dental metrics provides no basis for removing A. africanus from the ancestry of the Homo lineage.

  14. Metopic suture of Taung (Australopithecus africanus) and its implications for hominin brain evolution

    PubMed Central

    Falk, Dean; Zollikofer, Christoph P. E.; Morimoto, Naoki; Ponce de León, Marcia S.

    2012-01-01

    The type specimen for Australopithecus africanus (Taung) includes a natural endocast that reproduces most of the external morphology of the right cerebral hemisphere and a fragment of fossilized face that articulates with the endocast. Despite the fact that Taung died between 3 and 4 y of age, the endocast reproduces a small triangular-shaped remnant of the anterior fontanelle, from which a clear metopic suture (MS) courses rostrally along the midline [Hrdlička A (1925) Am J Phys Anthropol 8:379–392]. Here we describe and interpret this feature of Taung in light of comparative fossil and actualistic data on the timing of MS closure. In great apes, the MS normally fuses shortly after birth, such that unfused MS similar to Taung’s are rare. In humans, however, MS fuses well after birth, and partially or unfused MS are frequent. In gracile fossil adult hominins that lived between ∼3.0 and 1.5 million y ago, MS are also relatively frequent, indicating that the modern human-like pattern of late MS fusion may have become adaptive during early hominin evolution. Selective pressures favoring delayed fusion might have resulted from three aspects of perinatal ontogeny: (i) the difficulty of giving birth to large-headed neonates through birth canals that were reconfigured for bipedalism (the “obstetric dilemma”), (ii) high early postnatal brain growth rates, and (iii) reorganization and expansion of the frontal neocortex. Overall, our data indicate that hominin brain evolution occurred within a complex network of fetopelvic constraints, which required modification of frontal neurocranial ossification patterns. PMID:22566620

  15. Metopic suture of Taung (Australopithecus africanus) and its implications for hominin brain evolution.

    PubMed

    Falk, Dean; Zollikofer, Christoph P E; Morimoto, Naoki; Ponce de León, Marcia S

    2012-05-29

    The type specimen for Australopithecus africanus (Taung) includes a natural endocast that reproduces most of the external morphology of the right cerebral hemisphere and a fragment of fossilized face that articulates with the endocast. Despite the fact that Taung died between 3 and 4 y of age, the endocast reproduces a small triangular-shaped remnant of the anterior fontanelle, from which a clear metopic suture (MS) courses rostrally along the midline [Hrdlička A (1925) Am J Phys Anthropol 8:379-392]. Here we describe and interpret this feature of Taung in light of comparative fossil and actualistic data on the timing of MS closure. In great apes, the MS normally fuses shortly after birth, such that unfused MS similar to Taung's are rare. In humans, however, MS fuses well after birth, and partially or unfused MS are frequent. In gracile fossil adult hominins that lived between ∼3.0 and 1.5 million y ago, MS are also relatively frequent, indicating that the modern human-like pattern of late MS fusion may have become adaptive during early hominin evolution. Selective pressures favoring delayed fusion might have resulted from three aspects of perinatal ontogeny: (i) the difficulty of giving birth to large-headed neonates through birth canals that were reconfigured for bipedalism (the "obstetric dilemma"), (ii) high early postnatal brain growth rates, and (iii) reorganization and expansion of the frontal neocortex. Overall, our data indicate that hominin brain evolution occurred within a complex network of fetopelvic constraints, which required modification of frontal neurocranial ossification patterns.

  16. Isolation, characterization, and biological activity of the Methanococcus thermolithotrophicus ferredoxin.

    PubMed Central

    Hatchikian, E C; Fardeau, M L; Bruschi, M; Belaich, J P; Chapman, A; Cammack, R

    1989-01-01

    A ferredoxin has been isolated from the thermophilic methanogen Methanococcus thermolithotrophicus. The native protein was a monomer exhibiting a molecular weight of 7,262, calculated from the amino acid composition. Its absorption spectrum had two maxima at 390 and 283 nm, with an absorbance ratio A390/A283 of 0.79. The absorption at 390 nm (E = 29 mM-1 cm-1) and the content of iron of the protein are in agreement with the presence of two 4Fe-4S clusters in M. thermolithotrophicus ferredoxin. Its amino acid composition showed the presence of eight cysteine residues, which is the required number of cysteines for the binding of two 4Fe-4S clusters. The protein was characterized by the lack of histidine, arginine, and leucine and a high content of valine. It was unusually stable to high temperatures but not to oxygen. The ESR spectrum of the protein in the oxidized state showed a minor signal at g = 2.01, corresponding to an oxidized 3Fe-4S cluster. The protein, which was difficult to reduce with dithionite or reduced mediators, exhibited in its reduced state a spectrum typical of two interacting reduced 4Fe-4S clusters. M. thermolithotrophicus ferredoxin functioned as an electron acceptor for the CO dehydrogenase complex with an extract free of ferredoxin. No reaction was detected with F420 or hydrogenase. PMID:2540148

  17. Ferredoxin-thioredoxin reductase: a catalytically active dithiol group links photoreduced ferredoxin to thioredoxin functional in photosynthetic enzyme regulation

    SciTech Connect

    Droux, M.; Miginiac-Maslow, M.; Jacquot, J.P.; Gadal, P.; Crawford, N.A.; Kosower, N.S.; Buchanan, B.B.

    1987-07-01

    The mechanism by which the ferredoxin-thioredoxin system activates the target enzyme, NADP-malate dehydrogenase, was investigated by analyzing the sulfhydryl status of individual protein components with (/sup 14/C)iodoacetate and monobromobimane. The data indicate that ferredoxin-thioredoxin reductase (FTR)--an iron-sulfur enzyme present in oxygenic photosynthetic organisms--is the first member of a thiol chain that links light to enzyme regulation. FTR possesses a catalytically active dithiol group localized on the 13 kDa (similar) subunit, that occurs in all species investigated and accepts reducing equivalents from photoreduced ferredoxin and transfers them stoichiometrically to the disulfide form of thioredoxin m. The reduced thioredoxin m, in turn, reduces NADP-malate dehydrogenase, thereby converting it from an inactive (S-S) to an active (SH) form. The means by which FTR is able to combine electrons (from photoreduced ferredoxin) with protons (from the medium) to reduce its active disulfide group remains to be determined.

  18. Human evolution. Response to Comment on "Human-like hand use in Australopithecus africanus".

    PubMed

    Skinner, Matthew M; Stephens, Nicholas B; Tsegai, Zewdi J; Foote, Alexandra C; Nguyen, N Huynh; Gross, Thomas; Pahr, Dieter H; Hublin, Jean-Jacques; Kivell, Tracy L

    2015-06-05

    Almécija and colleagues claim that we apply a simplified understanding of bone functional adaptation and that our results of human-like hand use in Australopithecus africanus are not novel. We argue that our results speak to actual behavior, rather than potential behaviors, and our functional interpretation is well supported by our methodological approach, comparative sample, and previous experimental data.

  19. Genome Sequence of Mercury-Methylating and Pleomorphic Desulfovibrio africanus strain Walvis Bay

    SciTech Connect

    Brown, Steven D; Wall, Judy D.; Kucken, A M; Gilmour, C C; Podar, Mircea; Brandt, Craig C; Teshima, Hazuki; Detter, J C; Han, Cliff; Land, Miriam L; Lucas, Susan; Han, James; Pennacchio, Len; Nolan, Matt; Pitluck, Samual; Woyke, Tanja; Goodwin, Lynne A.; Palumbo, Anthony Vito; Elias, Dwayne A

    2011-01-01

    Desulfovibrio africanus strain Walvis Bay is an anaerobic sulfate-reducing bacterium capable of producing methylmercury (MeHg), a potent human neurotoxin. The mechanism of methylation by this and other organisms is unknown. We present the 4.2-Mb genome sequence to provide further insight into microbial mercury methylation and sulfate-reducing bacteria.

  20. Laser flash absorption spectroscopy study of ferredoxin reduction by photosystem I: spectral and kinetic evidence for the existence of several photosystem I-ferredoxin complexes.

    PubMed

    Sétif, P Q; Bottin, H

    1995-07-18

    The existence of three first-order phases has been previously reported for the reduction of soluble ferredoxin by photosystem I (PSI), both from the cyanobacterium Synechocystis sp. PCC 6803 (at pH 8 and in the presence of salts) [Sétif, P. Q. Y., & Bottin, H. (1994) Biochemistry 33, 8495-8504]. The spectra of these three phases (t1/2 < 1 microsecond, = 13-20 and 103-123 microseconds) have been measured between 460 and 600 nm. All of them are fully consistent with electron transfer from (FA,FB)-, the terminal 4Fe-4S acceptors of PSI, to ferredoxin. Though the three spectra deviate significantly from the spectrum that can be calculated independently for this process, their sum closely matches the calculated spectrum. A detailed examination of these deviations indicates that the intermediate (13-20 microseconds) and slow (103-123 microseconds) first-order phases are associated with two distinct ferredoxin-binding sites on PSI. Under the same conditions, a fourth phase of negative amplitude is also observed in the 460-600 nm region. It is ascribed to reoxidation of reduced ferredoxin by an unknown species. The kinetic properties of this process show that it is triggered by collision of free ferredoxin with a preformed PSI-ferredoxin complex. Taking this reaction into account, it is shown that the relative proportions of the three first-order phases of ferredoxin reduction do not depend upon the ferredoxin concentration, indicating that the different sites of ferredoxin binding are mutually exclusive. The kinetics of ferredoxin reduction were also studied at pH 5.8, in the absence of salts. Under these conditions, the affinity of ferredoxin for PSI is much higher than at pH 8 (dissociation constant approximately 0.05 microM versus 0.6 microM) and the kinetics of ferredoxin reduction are much faster (a major submicrosecond phase and a single first-order microsecond phase with t1/2 approximately 9 microseconds), whereas a third, slower first-order phase is essentially

  1. Amino acid sequences of heterotrophic and photosynthetic ferredoxins from the tomato plant (Lycopersicon esculentum Mill.).

    PubMed

    Kamide, K; Sakai, H; Aoki, K; Sanada, Y; Wada, K; Green, L S; Yee, B C; Buchanan, B B

    1995-11-01

    Several forms (isoproteins) of ferredoxin in roots, leaves, and green and red pericarps in tomato plants (Lycopersicon esculentum Mill.) were earlier identified on the basis of N-terminal amino acid sequence and chromatographic behavior (Green et al. 1991). In the present study, a large scale preparation made possible determination of the full length amino acid sequence of the two ferredoxins from leaves. The ferredoxins characteristic of fruit and root were sequenced from the amino terminus to the 30th residue or beyond. The leaf ferredoxins were confirmed to be expressed in pericarp of both green and red fruit. The ferredoxins characteristic of fruit and root appeared to be restricted to those tissue. The results extend earlier findings in demonstrating that ferredoxin occurs in the major organs of the tomato plant where it appears to function irrespective of photosynthetic competence.

  2. Expression in Escherichia coli and characterization of a recombinant 7Fe ferredoxin of Rhodobacter capsulatus.

    PubMed Central

    Jouanneau, Y; Duport, C; Meyer, C; Gaillard, J

    1992-01-01

    The 7Fe ferredoxin of Rhodobacter capsulatus (FdII) could be expressed in Escherichia coli by cloning the fdxA gene coding for FdII downstream from the lac promoter. The expressed recombinant ferredoxin appeared as a brown protein which was specifically recognized in E. coli cell-free extracts by anti-FdII serum. The purified recombinant ferredoxin was indistinguishable from R. capsulatus FdII on the basis of its molecular, redox and spectroscopic properties. These results indicate that the [3Fe-4S] and [4Fe-4S] clusters were correctly inserted into the recombinant ferredoxin. Images Fig. 2. PMID:1325780

  3. Influence of Temperature on Multiplication and Egg Hatching of Longidorus africanus

    PubMed Central

    Ploeg, Antoon T.

    1999-01-01

    Longidorus africanus multiplication on tomato was highest at 29 °C. Few nematodes were recovered after 6 weeks at soil temperatures of 35 °C or below 23 °C. The time to egg hatching was shortest and the percentage of eggs hatching was highest at 29 °C. The minimum temperature and the heat sum above this temperature required for egg development were calculated to be 14.3 °C and 94.08 degree-days, respectively. The thermal times required for egg development by L. africanus and L. elongatus were nearly identical. For both species the product of the base temperature and the heat sum was near constant, and at a temperature of 22.3 °C the rates of egg development were equal. PMID:19270878

  4. Delineating a New Heterothallic Species of Volvox (Volvocaceae, Chlorophyceae) Using New Strains of "Volvox africanus".

    PubMed

    Nozaki, Hisayoshi; Matsuzaki, Ryo; Yamamoto, Kayoko; Kawachi, Masanobu; Takahashi, Fumio

    2015-01-01

    The volvocine algae represent an excellent model lineage in which to study evolution of female and male genders based on comparative analyses of related species. Among these species, Volvox carteri has been extensively studied as a model of an oogamous and complex organism. However, it may have unique derived features that are not present in other species of Volvox. Therefore, information regarding the characteristics of sexual reproduction of other species of Volvox is also important. In 1971, Starr studied four types of sexuality in several global strains identified as Volvox africanus; however, further taxonomic studies of these strains have been lacking, and strains of three of the four sexual types are not available. Here, we studied the morphology, sexual reproduction, and taxonomy of two V. africanus-like species isolated recently from Lake Biwa, Japan. These two species were very similar to two sexual types described by Starr in 1971: one producing dioecious sexual spheroids in heterothallic strains and the other forming both male spheroids and monoecious spheroids in a single strain. The former species produced zygotes with a reticulate cell wall, whereas a smooth zygote wall was observed in the latter species as in V. africanus previously reported from various localities around the world. Our multigene phylogenetic analysis demonstrated that these are sister species to each other. However, the presence of a compensatory base change in the most conserved region of the secondary structure of nuclear ribosomal DNA internal transcribed spacer-2, hybrid inviability demonstrated by intercrossing experiments, and morphological differences in the density of abutment between the gelatinous material of adjacent cells (individual sheaths) in the spheroid supported the recognition of the two species, V. africanus having a smooth zygote wall and V. reticuliferus Nozaki sp. nov. having a reticulate zygote wall.

  5. The description of Mediorhynchus africanus n. sp. (Acanthocephala: Gigantorhynchidae) from galliform birds in Africa.

    PubMed

    Amin, Omar M; Evans, Paul; Heckmann, Richard A; El-Naggar, Atif M

    2013-08-01

    Mediorhynchus africanus n. sp. is described from specimens collected from the helmeted guinea fowls, Numida meliagris Linn. 1758 in Kruger National Park and elsewhere in subSaharan Africa from the same and other galliform birds. These specimens were previously assigned to Mediorhynchus gallinarum Bhaleroa (Proc Zool Soc Lond Ser B Syst Morph 107:199-203, 1937) described from chickens, Gallus gallus L. in India and subsequently reported from other Asian countries. The identification of the African forms as M. gallinarum was based on similarities in the structure and measurements of the proboscis, proboscis armature and receptacle, lemnisci, and reproductive organs. A detailed study of specimens from South Africa and descriptions reported from elsewhere in Africa revealed marked differences that clearly distinguish the African material as new species. The African specimens are pseudo-segmented and flattened, the proboscis has two prominent apical pores, sensory pits are prevalent throughout the trunk, the posterior end of the female is broad with dorso-terminal dome-like extension opposite the subterminal gonopore, and the eggs are large. The Asian specimens from Indonesia and elsewhere are cylindrical and non-segmented, the proboscis lacks prominent apical pores, sensory pits are rare on the trunk, the posterior end of the female is pointed with a terminal gonopore, and the eggs are markedly smaller. We used DNA sequence from one mitochondrial gene (cytochrome oxidase subunit I) and one nuclear gene (18S ribosomal RNA) to infer the phylogenetic relationships of M. africanus and M. gallinarum and selected Acanthocephala. Medioryhnchus is monophyletic and M. africanus and M. gallinarum are allopatric sister species (9.7% sequence divergence). All findings indicate that M. africanus should be ranked as a separate species.

  6. Human evolution. Comment on "Human-like hand use in Australopithecus africanus".

    PubMed

    Almécija, Sergio; Wallace, Ian J; Judex, Stefan; Alba, David M; Moyà-Solà, Salvador

    2015-06-05

    Skinner and colleagues (Research Article, 23 January 2015, p. 395), based on metacarpal trabecular bone structure, argue that Australopithecus africanus employed human-like dexterity for stone tool making and use 3 million years ago. However, their evolutionary and biological assumptions are misinformed, failing to refute the previously existing hypothesis that human-like manipulation preceded systematized stone tool manufacture, as indicated by the fossil record.

  7. X-ray structure of a soluble Rieske-type ferredoxin from Mus musculus

    SciTech Connect

    Levin, Elena J.; Elsen, Nathaniel L.; Seder, Kory D.; McCoy, Jason G.; Fox, Brian G; Phillips, Jr., George N.

    2009-03-11

    The 2.07 {angstrom} resolution X-ray crystal structure of a soluble Rieske-type ferredoxin from Mus musculus encoded by the gene Mm.266515 is reported. Although they are present as covalent domains in eukaryotic membrane oxidase complexes, soluble Rieske-type ferredoxins have not previously been observed in eukaryotes. The overall structure of the mouse Rieske-type ferredoxin is typical of this class of iron-sulfur proteins and consists of a larger partial {beta}-barrel domain and a smaller domain containing Cys57, His59, Cys80 and His83 that binds the [2Fe-2S] cluster. The S atoms of the cluster are hydrogen-bonded by six backbone amide N atoms in a pattern typical of membrane-bound high-potential eukaryotic respiratory Rieske ferredoxins. However, phylogenetic analysis suggested that the mouse Rieske-type ferredoxin was more closely related to bacterial Rieske-type ferredoxins. Correspondingly, the structure revealed an extended loop most similar to that seen in Rieske-type ferredoxin subunits of bacterial aromatic dioxygenases, including the positioning of an aromatic side chain (Tyr85) between this loop and the [2Fe-2S] cluster. The mouse Rieske-type ferredoxin was shown to be capable of accepting electrons from both eukaryotic and prokaryotic oxidoreductases, although it was unable to serve as an electron donor for a bacterial monooxygenase complex. The human homolog of mouse Rieske-type ferredoxin was also cloned and purified. It behaved identically to mouse Rieske-type ferredoxin in all biochemical characterizations but did not crystallize. Based on its high sequence identity, the structure of the human homolog is likely to be modeled well by the mouse Rieske-type ferredoxin structure.

  8. Trabecular Evidence for a Human-Like Gait in Australopithecus africanus

    PubMed Central

    Raichlen, David; Pontzer, Herman; Warrener, Anna G.; Hublin, Jean-Jacques

    2013-01-01

    Although the earliest known hominins were apparently upright bipeds, there has been mixed evidence whether particular species of hominins including those in the genus Australopithecus walked with relatively extended hips, knees and ankles like modern humans, or with more flexed lower limb joints like apes when bipedal. Here we demonstrate in chimpanzees and humans a highly predictable and sensitive relationship between the orientation of the ankle joint during loading and the principal orientation of trabecular bone struts in the distal tibia that function to withstand compressive forces within the joint. Analyses of the orientation of these struts using microCT scans in a sample of fossil tibiae from the site of Sterkfontein, of which two are assigned to Australopithecus africanus, indicate that these hominins primarily loaded their ankles in a relatively extended posture like modern humans and unlike chimpanzees. In other respects, however, trabecular properties in Au africanus are distinctive, with values that mostly fall between those of chimpanzees and humans. These results indicate that Au. africanus, like Homo, walked with an efficient, extended lower limb. PMID:24223719

  9. Complete mitogenomes of Guinean angelfish (Holacanthus africanus) and Rock beauty (Holacanthus tricolor) (Teleostei: Pomacanthidae).

    PubMed

    Shen, Kang-Ning; Chen, Ching-Hung; Hsiao, Chung-Der

    2016-07-01

    In this study, we used the next-generation sequencing method to deduce two complete mitogenomes of Guinean angelfish (Holacanthus africanus) and Rock beauty (Holacanthus tricolor) for the first time. The assembled mitogenome, consisting of 16,819 bp and 16,625 bp in length, shows 87% similarity with each other. Both mitogenomes follow the typical vertebrate arrangement, including 13 protein-coding genes, 22 transfer RNAs, 2 ribosomal RNAs genes, and a non-coding control region of D-loop. The D-loop contains 1107 bp in H. africanus and 905 bp in H. tricolor and is located between tRNA-Pro and tRNA-Phe. The overall GC content is 46.2% for H. africanus and 45.6% for H. tricolor. The complete mitogenome of Guinean angelfish and Rock beauty deduced in this study provides essential and important DNA molecular data for further phylogenetic and evolutionary analysis for marine angelfish.

  10. Trabecular evidence for a human-like gait in Australopithecus africanus.

    PubMed

    Barak, Meir M; Lieberman, Daniel E; Raichlen, David; Pontzer, Herman; Warrener, Anna G; Hublin, Jean-Jacques

    2013-01-01

    Although the earliest known hominins were apparently upright bipeds, there has been mixed evidence whether particular species of hominins including those in the genus Australopithecus walked with relatively extended hips, knees and ankles like modern humans, or with more flexed lower limb joints like apes when bipedal. Here we demonstrate in chimpanzees and humans a highly predictable and sensitive relationship between the orientation of the ankle joint during loading and the principal orientation of trabecular bone struts in the distal tibia that function to withstand compressive forces within the joint. Analyses of the orientation of these struts using microCT scans in a sample of fossil tibiae from the site of Sterkfontein, of which two are assigned to Australopithecus africanus, indicate that these hominins primarily loaded their ankles in a relatively extended posture like modern humans and unlike chimpanzees. In other respects, however, trabecular properties in Au africanus are distinctive, with values that mostly fall between those of chimpanzees and humans. These results indicate that Au. africanus, like Homo, walked with an efficient, extended lower limb.

  11. Biochemical and crystallographic characterization of ferredoxin-NADP(+) reductase from nonphotosynthetic tissues.

    PubMed

    Aliverti, A; Faber, R; Finnerty, C M; Ferioli, C; Pandini, V; Negri, A; Karplus, P A; Zanetti, G

    2001-12-04

    Distinct forms of ferredoxin-NADP(+) reductase are expressed in photosynthetic and nonphotosynthetic plant tissues. Both enzymes catalyze electron transfer between NADP(H) and ferredoxin; whereas in leaves the enzyme transfers reducing equivalents from photoreduced ferredoxin to NADP(+) in photosynthesis, in roots it has the opposite physiological role, reducing ferredoxin at the expense of NADPH mainly for use in nitrate assimilation. Here, structural and kinetic properties of a nonphotosynthetic isoform were analyzed to define characteristics that may be related to tissue-specific function. Compared with spinach leaf ferredoxin-NADP(+) reductase, the recombinant corn root isoform showed a slightly altered absorption spectrum, a higher pI, a >30-fold higher affinity for NADP(+), greater susceptibility to limited proteolysis, and an approximately 20 mV more positive redox potential. The 1.7 A resolution crystal structure is very similar to the structures of ferredoxin-NADP(+) reductases from photosynthetic tissues. Four distinct structural features of this root ferredoxin-NADP(+) reductases are an alternate conformation of the bound FAD molecule, an alternate path for the amino-terminal extension, a disulfide bond in the FAD-binding domain, and changes in the surface that binds ferredoxin.

  12. Characterization of a redox active cross-linked complex between cyanobacterial photosystem I and soluble ferredoxin.

    PubMed Central

    Lelong, C; Boekema, E J; Kruip, J; Bottin, H; Rögner, M; Sétif, P

    1996-01-01

    A covalent stoichiometric complex between photosystem I (PSI) and ferredoxin from the cyanobacterium Synechocystis sp. PCC 6803 was generated by chemical cross-linking. The photoreduction of ferredoxin, studied by laser flash absorption spectroscopy between 460 and 600 nm, is a fast process in 60% of the covalent complexes, which exhibit spectral and kinetic properties very similar to those observed with the free partners. Two major phases with t(1/2) <1 micros and approximately 10-14 micros are observed at two different pH values (5.8 and 8.0). The remaining complexes do not undergo fast ferredoxin reduction and 20-25% of the complexes are still able to reduce free ferredoxin or flavodoxin efficiently, thus indicating that ferredoxin is not bound properly in this proportion of covalent complexes. The docking site of ferredoxin on PSI was determined by electron microscopy in combination with image analysis. Ferredoxin binds to the cytoplasmic side of PSI, with its mass center 77 angstroms distant from the center of the trimer and in close contact with a ridge formed by the subunits PsaC, PsaD and PsaE. This docking site corresponds to a close proximity between the [2Fe- 2S] center of ferredoxin and the terminal [4Fe-4S] acceptor FII of PSI and is very similar in position to the docking site of flavodoxin, an alternative electron acceptor of PSI. Images PMID:8641281

  13. Laser flash absorption spectroscopy study of ferredoxin reduction by photosystem I: Spectral and kinetic evidence for the existence of several photosystem I-ferredoxin complexes

    SciTech Connect

    Setif, P.Q.Y.; Bottin, H.

    1995-07-18

    The existence of three first-order phases has been previously reported for the reduction of soluble ferredoxin by photosystem I (PSI), both from the cyanobacterium Synechocystis sp. PCC 6803 (at pH 8 and in the presence of salts). The spectra of these three phases (t{sub 1/2} < {mu}s, = 13-20 and 103-123 {mu}s) have been measured between 460 and 600 nm. All of them are fully consistent with electron transfer from (F{sub A},F{sub B}){sup -}, the terminal 4Fe-4S acceptors of PSI, to ferredoxin. Though the three spectra deviate significantly from the spectrum that can be calculated independently for this process, their sum closely matches the calculated spectrum. A detailed examination of these deviations indicates that the intermediate (13-20 ps) and slow (103- 123 ys) first-order phases are associated with two distinct ferredoxin-binding sites on PSI. Under the same conditions, a fourth phase of negative amplitude is also observed in the 460-600 nm region. The kinetic properties of this process show that it is triggered by collision of free ferredoxin with a preformed PSI-ferredoxin complex. Taking this reaction into account, it is shown that the relative proportions of the three first-order phases of ferredoxin reduction do not depend upon the ferredoxin concentration, indicating that the different sites of ferredoxin binding are mutually exclusive. The kinetics of ferredoxin reduction were also studied at pH 5.8, in the absence of salts. Two similar first-order components are found for the reduction of spinach ferredoxin by PSI from Synechocystis at pH 8, though the apparent dissociation constant for the latter system is larger ({approx}5 {mu}M). Despite the different affinities of spinach and Synechocystis ferredoxins for the cyanobacterial PSI, similar second-order rate constants are found in both cases at pH 8 [(2-6) x 10{sup 8} M{sup -1} s{sup -1}]. 29 refs., 10 figs., 1 tab.

  14. Molecular scale photodiode composed of recombinant ferredoxin/chlorophyll a heterostructure.

    PubMed

    Choi, Jeong-Woo; Lee, Doo-Bong; Oh, Byung-Keun; Min, Junhong; Kim, Kun Soo

    2008-09-01

    Photoelectrical rectifying property of biomolecular heterostructures is investigated in molecular scale. Recombinant ferredoxin and chlorophyll a were used as an electron acceptor and a sensitizer respectively in the molecular layer by mimicking photosynthesis. A self-assembled monolayer of recombinant ferredoxin was formed on Au surface, and then chlorophyll a was deposited onto the recombinant ferredoxin layer by Langmuir-Blodgett method. The formation of recombinant ferredoxin/chlorophyll a hetero-layers was confirmed by the SPR (surface plasmon resonance) spectroscopy, and the surface was observed by the STM (scanning tunneling microscopy). The rectifying property by the STS (scanning-tunneling-spectroscopy) based current-voltage characteristics was achieved in the recombinant ferredoxin/chlorophyll a hetero-layers. Thus, proposed hetero-layers functioned as a rectifier that can be useful property for the development of molecular-scale bioelectronic devices.

  15. Human Mitochondrial Ferredoxin 1 (FDX1) and Ferredoxin 2 (FDX2) Both Bind Cysteine Desulfurase and Donate Electrons for Iron–Sulfur Cluster Biosynthesis

    PubMed Central

    2016-01-01

    Ferredoxins play an important role as an electron donor in iron–sulfur (Fe–S) cluster biosynthesis. Two ferredoxins, human mitochondrial ferredoxin 1 (FDX1) and human mitochondrial ferredoxin 2 (FDX2), are present in the matrix of human mitochondria. Conflicting results have been reported regarding their respective function in mitochondrial iron–sulfur cluster biogenesis. We report here biophysical studies of the interaction of these two ferredoxins with other proteins involved in mitochondrial iron–sulfur cluster assembly. Results from nuclear magnetic resonance spectroscopy show that both FDX1 and FDX2 (in both their reduced and oxidized states) interact with the protein complex responsible for cluster assembly, which contains cysteine desulfurase (NFS1), ISD11 (also known as LYRM4), and acyl carrier protein (Acp). In all cases, ferredoxin residues close to the Fe–S cluster are involved in the interaction with this complex. Isothermal titration calorimetry results showed that FDX2 binds more tightly to the cysteine desulfurase complex than FDX1 does. The reduced form of each ferredoxin became oxidized in the presence of the cysteine desulfurase complex when l-cysteine was added, leading to its conversion to l-alanine and the generation of sulfide. In an in vitro reaction, the reduced form of each ferredoxin was found to support Fe–S cluster assembly on ISCU; the rate of cluster assembly was faster with FDX2 than with FDX1. Taken together, these results show that both FDX1 and FDX2 can function in Fe–S cluster assembly in vitro. PMID:28001042

  16. Human Mitochondrial Ferredoxin 1 (FDX1) and Ferredoxin 2 (FDX2) Both Bind Cysteine Desulfurase and Donate Electrons for Iron-Sulfur Cluster Biosynthesis.

    PubMed

    Cai, Kai; Tonelli, Marco; Frederick, Ronnie O; Markley, John L

    2017-01-24

    Ferredoxins play an important role as an electron donor in iron-sulfur (Fe-S) cluster biosynthesis. Two ferredoxins, human mitochondrial ferredoxin 1 (FDX1) and human mitochondrial ferredoxin 2 (FDX2), are present in the matrix of human mitochondria. Conflicting results have been reported regarding their respective function in mitochondrial iron-sulfur cluster biogenesis. We report here biophysical studies of the interaction of these two ferredoxins with other proteins involved in mitochondrial iron-sulfur cluster assembly. Results from nuclear magnetic resonance spectroscopy show that both FDX1 and FDX2 (in both their reduced and oxidized states) interact with the protein complex responsible for cluster assembly, which contains cysteine desulfurase (NFS1), ISD11 (also known as LYRM4), and acyl carrier protein (Acp). In all cases, ferredoxin residues close to the Fe-S cluster are involved in the interaction with this complex. Isothermal titration calorimetry results showed that FDX2 binds more tightly to the cysteine desulfurase complex than FDX1 does. The reduced form of each ferredoxin became oxidized in the presence of the cysteine desulfurase complex when l-cysteine was added, leading to its conversion to l-alanine and the generation of sulfide. In an in vitro reaction, the reduced form of each ferredoxin was found to support Fe-S cluster assembly on ISCU; the rate of cluster assembly was faster with FDX2 than with FDX1. Taken together, these results show that both FDX1 and FDX2 can function in Fe-S cluster assembly in vitro.

  17. X-ray structure of a soluble Rieske-type ferredoxin from Mus musculus

    SciTech Connect

    Levin, Elena J.; Elsen, Nathaniel L.; Seder, Kory D.; McCoy, Jason G.; Fox, Brian G.; Phillips Jr, George N.

    2008-09-01

    The X-ray crystal structure of a soluble Rieske ferredoxin from M. musculus was solved at 2.07 Å resolution, revealing an iron–sulfur cluster-binding domain with similar architecture to the Rieske-type domains of bacterial aromatic dioxygenases. The ferredoxin was also shown to be capable of accepting electrons from both eukaryotic and prokaryotic oxidoreductases. The 2.07 Å resolution X-ray crystal structure of a soluble Rieske-type ferredoxin from Mus musculus encoded by the gene Mm.266515 is reported. Although they are present as covalent domains in eukaryotic membrane oxidase complexes, soluble Rieske-type ferredoxins have not previously been observed in eukaryotes. The overall structure of the mouse Rieske-type ferredoxin is typical of this class of iron–sulfur proteins and consists of a larger partial β-barrel domain and a smaller domain containing Cys57, His59, Cys80 and His83 that binds the [2Fe–2S] cluster. The S atoms of the cluster are hydrogen-bonded by six backbone amide N atoms in a pattern typical of membrane-bound high-potential eukaryotic respiratory Rieske ferredoxins. However, phylogenetic analysis suggested that the mouse Rieske-type ferredoxin was more closely related to bacterial Rieske-type ferredoxins. Correspondingly, the structure revealed an extended loop most similar to that seen in Rieske-type ferredoxin subunits of bacterial aromatic dioxygenases, including the positioning of an aromatic side chain (Tyr85) between this loop and the [2Fe–2S] cluster. The mouse Rieske-type ferredoxin was shown to be capable of accepting electrons from both eukaryotic and prokaryotic oxidoreductases, although it was unable to serve as an electron donor for a bacterial monooxygenase complex. The human homolog of mouse Rieske-type ferredoxin was also cloned and purified. It behaved identically to mouse Rieske-type ferredoxin in all biochemical characterizations but did not crystallize. Based on its high sequence identity, the structure of the

  18. Molecular Cloning and Differential Expression of the Maize Ferredoxin Gene Family 1

    PubMed Central

    Hase, Toshiharu; Kimata, Yoko; Yonekura, Keiko; Matsumura, Tomohiko; Sakakibara, Hitoshi

    1991-01-01

    In maize (Zea mays L.), four ferredoxin (Fd) isoproteins, Fd I to Fd IV, are differentially distributed in photosynthetic and nonphotosynthetic organs of young seedlings (Y Kimata, T Hase [1989] Plant Physiol 89: 1193-1197). To understand structural characteristics of the Fd isoproteins and molecular mechanism of the differential expression of their genes, we have cloned and characterized three different maize Fd cDNAs. DNA sequence analyses showed that two of the cDNAs encoded the entire precursor polypeptides of Fd I and Fd III, which were composed of 150 and 152 amino acid residues, respectively, and the other encoded a 135 amino acid precursor polypeptide of Fd not yet identified. High degrees of homologies were found in the deduced amino acid sequences of mature regions of these Fd isoproteins, but the transit peptide of Fd III differed considerably from those of other Fd isoproteins. Fd I and the unidentified Fd were encoded mainly with codons ending in C or G, but such strong codon bias was not seen in Fd III. Gene specific probes for each cDNA were used to probe Northern blots of RNA isolated from leaves, mesocotyls, and roots of maize seedlings. The gene transcripts for Fd I and the unidentified Fd were restricted to leaves and their levels increased markedly upon illumination of etiolated seedlings, whereas that for Fd III was detected in all organs and its accumulation was not light dependent. This organ specific accumulation of Fd mRNAs corresponds exactly to the distribution pattern of Fd isoproteins. ImagesFigure 1Figure 5Figure 6Figure 7Figure 8 PMID:16668188

  19. The structural rigidity of the cranium of Australopithecus africanus: implications for diet, dietary adaptations, and the allometry of feeding biomechanics.

    PubMed

    Strait, David S; Grosse, Ian R; Dechow, Paul C; Smith, Amanda L; Wang, Qian; Weber, Gerhard W; Neubauer, Simon; Slice, Dennis E; Chalk, Janine; Richmond, Brian G; Lucas, Peter W; Spencer, Mark A; Schrein, Caitlin; Wright, Barth W; Byron, Craig; Ross, Callum F

    2010-04-01

    Australopithecus africanus is an early hominin (i.e., human relative) believed to exhibit stress-reducing adaptations in its craniofacial skeleton that may be related to the consumption of resistant food items using its premolar teeth. Finite element analyses simulating molar and premolar biting were used to test the hypothesis that the cranium of A. africanus is structurally more rigid than that of Macaca fascicularis, an Old World monkey that lacks derived australopith facial features. Previously generated finite element models of crania of these species were subjected to isometrically scaled loads, permitting a direct comparison of strain magnitudes. Moreover, strain energy (SE) in the models was compared after results were scaled to account for differences in bone volume and muscle forces. Results indicate that strains in certain skeletal regions below the orbits are higher in M. fascicularis than in A. africanus. Moreover, although premolar bites produce von Mises strains in the rostrum that are elevated relative to those produced by molar biting in both species, rostral strains are much higher in the macaque than in the australopith. These data suggest that at least the midface of A. africanus is more rigid than that of M. fascicularis. Comparisons of SE reveal that the A. africanus cranium is, overall, more rigid than that of M. fascicularis during premolar biting. This is consistent with the hypothesis that this hominin may have periodically consumed large, hard food items. However, the SE data suggest that the A. africanus cranium is marginally less rigid than that of the macaque during molar biting. It is hypothesized that the SE results are being influenced by the allometric scaling of cranial cortical bone thickness.

  20. Body proportions of Australopithecus afarensis and A. africanus and the origin of the genus Homo.

    PubMed

    McHenry, H M; Berger, L R

    1998-07-01

    New discoveries of A. africanus fossils from Member 4 Sterkfontein reveal a body form quite unlike earlier Australopithecus species. The new adult material consists of over 48 fore- and hindlimb specimens and includes an associated partial skeleton, Stw 431. The forelimbs and relatively large: the average size of their joints corresponds to a modern human with body mass of 53 kg. The hindlimbs are much smaller with an average size matching a modern human of only 33 kg. Analyses of the Stw 431 partial skeleton confirm these results. In contrast, A. afarensis and anamensis more closely approximate a human pattern of forelimb joint size. This is an unanticipated complication in our understanding of early human evolution. In general, craniodental morphology tracks time in species of Australopithecus: A. anamensis (3.5-4.1 Ma) is the the most primitive with a strongly sloping symphysis, large canine roots, etc., A. afarensis (3.0-3.6 Ma) is less primitive, and A. africanus (2.6-3.0 Ma) shares many derived characteristics with early Homo (e.g., expanded brain, reduced canine, bicuspid lower third premolar, reduced prognathism, greater flexion of the cranial base, deeper TMJ). the new postcranial material, however, reveals an apparently primitive morphology of relatively large forelimb and small hindlimb joints resembling more the pongid than the human pattern. More pongid-like proportions are also present in the two known associated partial skeletons of H. habilis (OH 62 KNM-ER 3735). This may imply either (1) that A. africanus and H. habilis evolved craniodental characters in parallel with the lineage leading to later Homo, or (2) that fore- to hindlimb proportions of A. afarensis (and perhaps A. anamensis) evolved independent of the lineage leading to Homo and does not imply a close phylogenetic link with Homo. Both of these explanations or any other phylogeny imply homoplasy.

  1. Study of the thiol/disulfide redox systems of the anaerobe Desulfovibrio vulgaris points out pyruvate:ferredoxin oxidoreductase as a new target for thioredoxin 1.

    PubMed

    Pieulle, Laetitia; Stocker, Pierre; Vinay, Manon; Nouailler, Matthieu; Vita, Nicolas; Brasseur, Gaël; Garcin, Edwige; Sebban-Kreuzer, Corinne; Dolla, Alain

    2011-03-11

    Sulfate reducers have developed a multifaceted adaptative strategy to survive against oxidative stresses. Along with this oxidative stress response, we recently characterized an elegant reversible disulfide bond-dependent protective mechanism in the pyruvate:ferredoxin oxidoreductase (PFOR) of various Desulfovibrio species. Here, we searched for thiol redox systems involved in this mechanism. Using thiol fluorescent labeling, we show that glutathione is not the major thiol/disulfide balance-controlling compound in four different Desulfovibrio species and that no other plentiful low molecular weight thiol can be detected. Enzymatic analyses of two thioredoxins (Trxs) and three thioredoxin reductases allow us to propose the existence of two independent Trx systems in Desulfovibrio vulgaris Hildenborough (DvH). The TR1/Trx1 system corresponds to the typical bacterial Trx system. We measured a TR1 apparent K(m) value for Trx1 of 8.9 μM. Moreover, our results showed that activity of TR1 was NADPH-dependent. The second system named TR3/Trx3 corresponds to an unconventional Trx system as TR3 used preferentially NADH (K(m) for NADPH, 743 μM; K(m) for NADH, 5.6 μM), and Trx3 was unable to reduce insulin. The K(m) value of TR3 for Trx3 was 1.12 μM. In vitro experiments demonstrated that the TR1/Trx1 system was the only one able to reactivate the oxygen-protected form of Desulfovibrio africanus PFOR. Moreover, ex vivo pulldown assays using the mutant Trx1(C33S) as bait allowed us to capture PFOR from the DvH extract. Altogether, these data demonstrate that PFOR is a new target for Trx1, which is probably involved in the protective switch mechanism of the enzyme.

  2. The carbon isotope ecology and diet of Australopithecus africanus at Sterkfontein, South Africa.

    PubMed

    van der Merwe, Nikolaas J; Thackeray, J Francis; Lee-Thorp, Julia A; Luyt, Julie

    2003-05-01

    The stable carbon isotope ratio of fossil tooth enamel carbonate is determined by the photosynthetic systems of plants at the base of the animal's foodweb. In subtropical Africa, grasses and many sedges have C(4)photosynthesis and transmit their characteristically enriched 13C/(12)C ratios (more positive delta13C values) along the foodchain to consumers. We report here a carbon isotope study of ten specimens of Australopithecus africanus from Member 4, Sterkfontein (ca. 2.5 to 2.0Ma), compared with other fossil mammals from the same deposit. This is the most extensive isotopic study of an early hominin species that has been achieved so far. The results show that this hominin was intensively engaged with the savanna foodweb and that the dietary variation between individuals was more pronounced than for any other early hominin or non-human primate species on record. Suggestions that more than one species have been incuded in this taxon are not supported by the isotopic evidence. We conclude that Australopithecus africanus was highly opportunistic and adaptable in its feeding habits.

  3. Lung fluke (Paragonimus africanus) infects Nigerian red-capped mangabeys and causes respiratory disease

    PubMed Central

    Friant, Sagan; Brown, Kelsey; Saari, Mason T.; Segel, Nicholas H.; Slezak, Julia; Goldberg, Tony L.

    2015-01-01

    Eggs of the lung fluke genus Paragonimus were detected in red-capped mangabeys (Cercocebus torquatus) in Nigeria. We assess the role of these primates as potential sylvatic hosts and the clinical effects of the parasite on monkeys. DNA sequenced from eggs in feces were 100% identical in the ITS2 region to Paragonimus africanus sequences from humans in Cameroon. Paragonimus-positive monkeys coughed more than uninfected monkeys. Experimental de-worming led to reduction in parasite intensity and a corresponding reduction of coughing to baseline levels in infected monkeys. This report provides the first evidence of Paragonimus sp. in C. torquatus, of P. africanus in Nigerian wildlife, and the first molecular evidence of the parasite in African wildlife. Coughing, sometimes interpreted as a communication behavior in primates, can actually indicate infection with lung parasites. Observations of coughing in primates may, in turn, provide a useful mechanism for surveillance of Paragonimus spp, which are re-emerging human pathogens, in wildlife reservoirs. PMID:26543803

  4. Individual tooth macrowear pattern guides the reconstruction of Sts 52 (Australopithecus africanus) dental arches.

    PubMed

    Benazzi, Stefano; Kullmer, Ottmar; Schulz, Dieter; Gruppioni, Giorgio; Weber, Gerhard W

    2013-02-01

    The functional restoration of the occlusal relationship between maxillary and mandibular tooth rows is a major challenge in modern dentistry and maxillofacial surgery. Similar technical challenges are present in paleoanthropology when considering fragmented and deformed mandibular and maxillary fossils. Sts 52, an Australopithecus africanus specimen from Sterkfontein Member 4, represents a typical case where the original shape of the dental arches is no longer preserved. It includes a partial lower face (Sts 52a) and a fragmented mandible (Sts 52b), both incomplete and damaged to such an extent to thwart attempts at matching upper and lower dentitions. We show how the preserved macro wear pattern of the tooth crowns can be used to functionally reconstruct Sts 52's dental arches. High-resolution dental stone casts of Sts 52 maxillary and mandibular dentition were mounted and repositioned in a dental articulator. The occlusal relationship between antagonists was restored based on the analysis of the occlusal wear pattern of each preserved tooth, considering all dental contact movements represented in the occlusal compass. The reconstructed dental arches were three-dimensional surface scanned and their occlusal kinematics tested in a simulation. The outcome of this contribution is the first functional restoration of A. africanus dental arches providing new morphometric data for specimen Sts 52. It is noteworthy that the method described in this case study might be applied to several other fossil specimens.

  5. Lung fluke (Paragonimus africanus) infects Nigerian red-capped mangabeys and causes respiratory disease.

    PubMed

    Friant, Sagan; Brown, Kelsey; Saari, Mason T; Segel, Nicholas H; Slezak, Julia; Goldberg, Tony L

    2015-12-01

    Eggs of the lung fluke genus Paragonimus were detected in red-capped mangabeys (Cercocebus torquatus) in Nigeria. We assess the role of these primates as potential sylvatic hosts and the clinical effects of the parasite on monkeys. DNA sequenced from eggs in feces were 100% identical in the ITS2 region to Paragonimus africanus sequences from humans in Cameroon. Paragonimus-positive monkeys coughed more than uninfected monkeys. Experimental de-worming led to reduction in parasite intensity and a corresponding reduction of coughing to baseline levels in infected monkeys. This report provides the first evidence of Paragonimus sp. in C. torquatus, of P. africanus in Nigerian wildlife, and the first molecular evidence of the parasite in African wildlife. Coughing, sometimes interpreted as a communication behavior in primates, can actually indicate infection with lung parasites. Observations of coughing in primates may, in turn, provide a useful mechanism for surveillance of Paragonimus spp, which are re-emerging human pathogens, in wildlife reservoirs.

  6. Ferredoxin-linked chloreplast enzymes. Progress report, August 15, 1990--August 14, 1993

    SciTech Connect

    1996-01-01

    Progress has clearly been made on all of the goals set forth in the original proposal. Although the monoclonal antibodies raised against FNR turned out no to be useful for mapping the FNR/ferredoxin or FNR/NADP+ interaction domains, good progress has been made on mapping the FNR/ferredoxin interaction domains by an alternative technique, differential chemical modification. Furthermore, the techniques developed for differential chemical modifications of these two proteins - taurine modification of aspartate and glutamate residues and biotin modification of lysine residues - should be useful for mapping the interaction domains of many proteins that associate through electrostatic interactions. Finally, progress has also been made with respect to another ferredoxin-dependent enzyme involved in the earliest steps of plant nitrogen metabolism - nitrite reductase. Questions concerning the subunit composition and heme content of the enzyme have been resolved and evidence demonstrating the involvement of lysine and arginine residues in binding ferredoxin has been obtained for the first time.

  7. Ferredoxin from the hyperthermophile Thermotoga maritima is stable beyond the boiling point of water.

    PubMed

    Pfeil, W; Gesierich, U; Kleemann, G R; Sterner, R

    1997-10-03

    Heat-stable proteins from hyperthermophilic microorganisms are ideally suited for investigating protein stability and evolution. We measured with differential scanning calorimetry and optical absorption spectroscopy the thermal stability of [4Fe-4S] ferredoxin from Thermotoga maritima (tfdx), which is a small electron transfer protein. The results are consistent with two-state unfolding at the record denaturation temperature of 125 degrees C. According to the crystal structure at 1.75 A resolution, T. maritima ferredoxin contains a significantly increased number of hydrogen bonds that involve charged amino acid side-chains, compared to thermolabile ferredoxins. Thus, our results suggest that polar interactions substantially contribute to protein stability at very high temperatures. Moreover, because small [4Fe-4S] ferredoxins seem to have occurred early in evolution, the extreme thermostability of tfdx supports the hypothesis that life originated at high temperatures.

  8. Classification of iron-sulfur cores in ferredoxins by 1H nuclear magnetic resonance spectroscopy.

    PubMed

    Nagayama, K; Ozaki, Y; Kyogoku, Y; Hase, T; Matsubara, H

    1983-09-01

    A 1H nuclear magnetic resonance (NMR) study was carried out on various ferredoxins which possess one of three types of iron-sulfur clusters, (2Fe-2S), (3Fe-3S), or (4Fe-4S). In the isolated form, (2Fe-2S) ferredoxins from spinach (Spinacea oleracia), pokeweed (Phytolacca americana), a blue-green alga (Spirulina platensis), and a halobacterium (Halobacterium halobium) exhibited two broad resonances common in chemical shift at the region downfield of 10 ppm. In their reduced forms, seven contact-shifted resonances appeared spread over 30 ppm. Although the positions of the contact-shifted resonances in the reduced state differed among the four, a common trend in the temperature dependence of their resonance positions was recognized. Two (4Fe-4S) ferredoxins from Bacillus stearothermophilus and Bacillus thermoproteolyticus exhibited almost indistinguishable spectral patterns in both the oxidized and reduced forms. The ferricyanide-treated ferredoxins of B. stearothermophilus and B. thermoproteolyticus showed characteristic contact-shifted resonances distinct from the spectra of the original (4Fe-4S) ferredoxins. This corresponds to the recent finding of the interconversion of (4Fe-4S) and (3Fe-3S) clusters with ferricyanide in the ferredoxin. Based on our data together with reported NMR data on other ferredoxins, contact-shift resonances of three types of clusters were tabulated. The reliability of NMR classification increases when we compare the NMR spectra of a ferredoxin with the classification standards at the two redox states. Moreover, not only the absolute values of the chemical shifts of contact-shifted resonances but also their temperature dependence give distinctive information applicable to iron core identification.

  9. Fusion of Ferredoxin and Cytochrome P450 Enables Direct Light-Driven Biosynthesis

    PubMed Central

    2016-01-01

    Cytochrome P450s (P450s) are key enzymes in the synthesis of bioactive natural products in plants. Efforts to harness these enzymes for in vitro and whole-cell production of natural products have been hampered by difficulties in expressing them heterologously in their active form, and their requirement for NADPH as a source of reducing power. We recently demonstrated targeting and insertion of plant P450s into the photosynthetic membrane and photosynthesis-driven, NADPH-independent P450 catalytic activity mediated by the electron carrier protein ferredoxin. Here, we report the fusion of ferredoxin with P450 CYP79A1 from the model plant Sorghum bicolor, which catalyzes the initial step in the pathway leading to biosynthesis of the cyanogenic glucoside dhurrin. Fusion with ferredoxin allows CYP79A1 to obtain electrons for catalysis by interacting directly with photosystem I. Furthermore, electrons captured by the fused ferredoxin moiety are directed more effectively toward P450 catalytic activity, making the fusion better able to compete with endogenous electron sinks coupled to metabolic pathways. The P450-ferredoxin fusion enzyme obtains reducing power solely from its fused ferredoxin and outperforms unfused CYP79A1 in vivo. This demonstrates greatly enhanced electron transfer from photosystem I to CYP79A1 as a consequence of the fusion. The fusion strategy reported here therefore forms the basis for enhanced partitioning of photosynthetic reducing power toward P450-dependent biosynthesis of important natural products. PMID:27119279

  10. Endotoxin-induced coagulation reactions and phenoloxidase activity modulation in Sudanonautes africanus hemolymph fractions.

    PubMed

    Salawu, Musa Oyewole; Oloyede, Oyelola Bukoye

    2011-01-01

    Sudanonautes africanus is a freshwater crab local to Nigeria and West Africa that has no documentation of its innate immunity reactions. The objective of this study was to assess the effect of endotoxin (lipopolysaccharide [LPS]) on coagulation and on phenoloxidase (PO) activity in the hemolymph fractions of S. africanus. The hemolymph from each of 10 live crabs was obtained by carapace puncture and then fractionated into plasma and hemocytes. The hemocytes were then processed and then fractionated into hemocyte lysate (HL), hemocyte lysate supernatant (HLS), and hemocyte lysate debris (HLD). In one study, each fraction was then incubated with a fixed level of LPS in the presence or absence of exogenous calcium (Ca(2+)) ion. In another study, the LPS concentration was varied in order to study its effect on protein coagulation when an optimal ratio mixture of plasma:HLS was present as well as on PO activity in the plasma and HLS fractions. The results of the first set of studies demonstrated that a presence of Ca(2+) in the LPS-induced clotting reactions was essential. The next set of studies showed that a 7:1 plasma:HLS mixture yielded a higher level of coagulation than any other ratio tested in the presence of 1 EU LPS/ml. When this same plasma:HLS mixture ratio was used to ascertain the effect of varying LPS level on coagulation, the response trended higher up to a dose of 3.0 EU/ml., and decreased thereafter until 7 EU/ml. As expected based on the effect of LPS on PO activation, an increasing presence of LPS led to a general trend increase in activity of the enzyme in the plasma fraction; however, the effect was moreover inhibitory in the HLS fraction. From the results here, we conclude that protein coagulation is an important response, along with increased PO activity, that could manifest in Sudanonautes africanus after exposure to 'free' LPS or select LPS-bearing organisms in their environment.

  11. Ferredoxin containing bacteriocins suggest a novel mechanism of iron uptake in Pectobacterium spp.

    PubMed

    Grinter, Rhys; Milner, Joel; Walker, Daniel

    2012-01-01

    In order to kill competing strains of the same or closely related bacterial species, many bacteria produce potent narrow-spectrum protein antibiotics known as bacteriocins. Two sequenced strains of the phytopathogenic bacterium Pectobacterium carotovorum carry genes encoding putative bacteriocins which have seemingly evolved through a recombination event to encode proteins containing an N-terminal domain with extensive similarity to a [2Fe-2S] plant ferredoxin and a C-terminal colicin M-like catalytic domain. In this work, we show that these genes encode active bacteriocins, pectocin M1 and M2, which target strains of Pectobacterium carotovorum and Pectobacterium atrosepticum with increased potency under iron limiting conditions. The activity of pectocin M1 and M2 can be inhibited by the addition of spinach ferredoxin, indicating that the ferredoxin domain of these proteins acts as a receptor binding domain. This effect is not observed with the mammalian ferredoxin protein adrenodoxin, indicating that Pectobacterium spp. carries a specific receptor for plant ferredoxins and that these plant pathogens may acquire iron from the host through the uptake of ferredoxin. In further support of this hypothesis we show that the growth of strains of Pectobacterium carotovorum and atrosepticum that are not sensitive to the cytotoxic effects of pectocin M1 is enhanced in the presence of pectocin M1 and M2 under iron limiting conditions. A similar growth enhancement under iron limiting conditions is observed with spinach ferrodoxin, but not with adrenodoxin. Our data indicate that pectocin M1 and M2 have evolved to parasitise an existing iron uptake pathway by using a ferredoxin-containing receptor binding domain as a Trojan horse to gain entry into susceptible cells.

  12. A novel and remarkably thermostable ferredoxin from the hyperthermophilic archaebacterium Pyrococcus furiosus.

    PubMed Central

    Aono, S; Bryant, F O; Adams, M W

    1989-01-01

    The archaebacterium Pyrococcus furiosus is a strict anaerobe that grows optimally at 100 degrees C by a fermentative-type metabolism in which H2 and CO2 are the only detectable products. A ferredoxin, which functions as the electron donor to the hydrogenase of this organism was purified under anaerobic reducing conditions. It had a molecular weight of approximately 12,000 and contained 8 iron atoms and 8 cysteine residues/mol but lacked histidine or arginine residues. Reduction and oxidation of the ferredoxin each required 2 electrons/mol, which is consistent with the presence of two [4Fe-4S] clusters. The reduced protein gave rise to a broad rhombic electronic paramagnetic resonance spectrum, with gz = 2.10, gy = 1.86, gx = 1.80, and a midpoint potential of -345 mV (at pH 8). However, this spectrum represented a minor species, since it quantitated to only approximately 0.3 spins/mol. P. furiosus ferredoxin is therefore distinct from other ferredoxins in that the bulk of its iron is not present as iron-sulfur clusters with an S = 1/2 ground state. The apoferredoxin was reconstituted with iron and sulfide to give a protein that was indistinguishable from the native ferredoxin by its iron content and electron paramagnetic resonance properties, which showed that the novel iron-sulfur clusters were not artifacts of purification. The reduced ferredoxin also functioned as an electron donor for H2 evolution catalyzed by the hydrogenase of the mesophilic eubacterium Clostridium pasteurianum. P. furiosus ferredoxin was resistant to denaturation by sodium dodecyl sulfate (20%, wt/vol) and was remarkably thermostable. Its UV-visible absorption spectrum and electron carrier activity to P. furiosus hydrogenase were unaffected by a 12-h incubation of 95 degrees C. PMID:2542225

  13. Chromosomal rearrangements in a Somali wild ass pedigree, Equus africanus somaliensis (Perissodactyla, Equidae).

    PubMed

    Houck, M L; Kumamoto, A T; Cabrera, R M; Benirschke, K

    1998-01-01

    Chromosome analyses were conducted on 15 animals in a pedigree of Somali wild ass, Equus africanus somaliensis. G- and C-banded karyotypes are presented for the first time on this endangered species. The diploid number ranged from 62 to 64. Numerical chromosomal variation was the result of a centric fission which was accompanied by a heterochromatic deletion. The fission polymorphism involved acrocentric elements 19 and 21 as determined by G-banding. These autosomes are homologous to those involved in centric fission/fusion polymorphisms in other equids: E. asinus (domestic donkey), E. hemionus (onager), E. kiang (kiang), and E. burchelli (common zebra). Banding analyses also revealed a paracentric inversion polymorphism in submetacentric chromosome pair 2 of E. a. somaliensis. Both the centric fission and paracentric inversion polymorphisms involved heterochromatic regions. One individual was found to be heterozygous for two de novo chromosomal rearrangements: a centric fission (involving acrocentric elements 19 and 21) and a heterochromatic deletion of chromosome 2.

  14. Dual targeted poplar ferredoxin NADP(+) oxidoreductase interacts with hemoglobin 1.

    PubMed

    Jokipii-Lukkari, Soile; Kastaniotis, Alexander J; Parkash, Vimal; Sundström, Robin; Leiva-Eriksson, Nélida; Nymalm, Yvonne; Blokhina, Olga; Kukkola, Eija; Fagerstedt, Kurt V; Salminen, Tiina A; Läärä, Esa; Bülow, Leif; Ohlmeier, Steffen; Hiltunen, J Kalervo; Kallio, Pauli T; Häggman, Hely

    2016-06-01

    Previous reports have connected non-symbiotic and truncated hemoglobins (Hbs) to metabolism of nitric oxide (NO), an important signalling molecule involved in wood formation. We have studied the capability of poplar (Populus tremula × tremuloides) Hbs PttHb1 and PttTrHb proteins alone or with a flavin-protein reductase to relieve NO cytotoxicity in living cells. Complementation tests in a Hb-deficient, NO-sensitive yeast (Saccharomyces cerevisiae) Δyhb1 mutant showed that neither PttHb1 nor PttTrHb alone protected cells against NO. To study the ability of Hbs to interact with a reductase, ferredoxin NADP(+) oxidoreductase PtthFNR was characterized by sequencing and proteomics. To date, by far the greatest number of the known dual-targeted plant proteins are directed to chloroplasts and mitochondria. We discovered a novel variant of hFNR that lacks the plastid presequence and resides in cytosol. The coexpression of PttHb1 and PtthFNR partially restored NO resistance of the yeast Δyhb1 mutant, whereas PttTrHb coexpressed with PtthFNR failed to rescue growth. YFP fusion proteins confirmed the interaction between PttHb1 and PtthFNR in plant cells. The structural modelling results indicate that PttHb1 and PtthFNR are able to interact as NO dioxygenase. This is the first report on dual targeting of central plant enzyme FNR to plastids and cytosol.

  15. Identification of Global Ferredoxin Interaction Networks in Chlamydomonas reinhardtii*

    PubMed Central

    Peden, Erin A.; Boehm, Marko; Mulder, David W.; Davis, ReAnna; Old, William M.; King, Paul W.; Ghirardi, Maria L.; Dubini, Alexandra

    2013-01-01

    Ferredoxins (FDXs) can distribute electrons originating from photosynthetic water oxidation, fermentation, and other reductant-generating pathways to specific redox enzymes in different organisms. The six FDXs identified in Chlamydomonas reinhardtii are not fully characterized in terms of their biological function. In this report, we present data from the following: (a) yeast two-hybrid screens, identifying interaction partners for each Chlamydomonas FDX; (b) pairwise yeast two-hybrid assays measuring FDX interactions with proteins from selected biochemical pathways; (c) affinity pulldown assays that, in some cases, confirm and even expand the interaction network for FDX1 and FDX2; and (d) in vitro NADP+ reduction and H2 photo-production assays mediated by each FDX that verify their role in these two pathways. Our results demonstrate new potential roles for FDX1 in redox metabolism and carbohydrate and fatty acid biosynthesis, for FDX2 in anaerobic metabolism, and possibly in state transition. Our data also suggest that FDX3 is involved in nitrogen assimilation, FDX4 in glycolysis and response to reactive oxygen species, and FDX5 in hydrogenase maturation. Finally, we provide experimental evidence that FDX1 serves as the primary electron donor to two important biological pathways, NADPH and H2 photo-production, whereas FDX2 is capable of driving these reactions at less than half the rate observed for FDX1. PMID:24100040

  16. Photosystem I cyclic electron transport: Measurement of ferredoxin-plastoquinone reductase activity.

    PubMed

    Cleland, R E; Bendall, D S

    1992-12-01

    Absorbance changes of ferredoxin measured at 463 nm in isolated thylakoids were shown to arise from the activity of the enzyme ferredoxin-plastoquinone reductase (FQR) in cyclic electron transport. Under anaerobic conditions in the presence of DCMU and an appropriate concentration of reduced ferredoxin, a light-induced absorbance decrease due to further reduction of Fd was assigned to the oxidation of the other components in the cyclic pathway, primarily plastoquinone. When the light was turned off, Fd was reoxidised and this gave a direct quantitative measurement of the rate of cyclic electron transport due to the activity of FQR. This activity was sensitive to the classical inhibitor of cyclic electron transport, antimycin, and also to J820 and DBMIB. Antimycin had no effect on Fd reduction although this was inhibited by stigmatellin. This provides further evidence that there is a quinone reduction site outside the cytochrome bf complex. The effect of inhibitors of ferredoxin-NADP(+) reductase and experiments involving the modification of ferredoxin suggest that there may be some role for the reductase as a component of FQR. Contrary to expectations, NADPH2 inhibited FQR activity; ATP and ADP had no effect.

  17. The crystal structure of FdxA, a 7Fe ferredoxin from Mycobacterium smegmatis

    SciTech Connect

    Ricagno, Stefano; De Rosa, Matteo; Aliverti, Alessandro; Zanetti, Giuliana; Bolognesi, Martino . E-mail: martino.bolognesi@unimi.it

    2007-08-17

    Mycobacterium smegmatis ferredoxin FdxA, which has an orthologue ferredoxin in Mycobacterium tuberculosis, FdxC, contains both one [3Fe-4S] and one [4Fe-4S] cluster. M. smegmatis FdxA has been shown to be a preferred ferredoxin substrate of FprA [F. Fischer, D. Raimondi, A. Aliverti, G. Zanetti, Mycobacterium tuberculosis FprA, a novel bacterial NADPH-ferredoxin reductase, Eur. J. Biochem. 269 (2002) 3005-3013], an adrenodoxin reductase-like flavoprotein of M. tuberculosis, suggesting that M. tuberculosis FdxC could be the physiological partner of the enzyme in providing reducing power to the cytochromes P450. We report here the crystal structure of FdxA at 1.6 A resolution (R {sub factor} 16.5%, R {sub free} 20.2%). Besides providing an insight on protein architecture for this 106-residue ferredoxin, our crystallographic investigation highlights lability of the [4Fe-4S] center, which is shown to loose a Fe atom during crystal growth. Due to their high similarity (87% sequence identity), the structure here reported can be considered a valuable model for M. tuberculosis FdxC, thus representing a step forward in the study of the complex mycobacterial redox pathways.

  18. Ferredoxin molecular thin film with intrinsic switching mechanism for biomemory application.

    PubMed

    Yagati, Ajay Kumar; Kim, Sang-Uk; Min, Junhong; Choi, Jeong-Woo

    2010-05-01

    A biomemory device consisting of cysteine modified ferredoxin molecules which possess a memory effect via a charge transfer mechanism was developed. For achieving an efficient bioelectronic device, cysteine modified ferredoxin was developed by embodying cysteine residues in ferredoxin by site--directed mutagenesis method to directly coordinate with the gold (Au) surface without use of any additional linkers. The thin film formation of ferredoxin molecules on Au electrode is confirmed by surface plasmon resonance (SPR) spectroscopy and scanning tunneling microscope (STM). Cyclic voltammetry (CV) and open circuit potential amperometry (OCPA) methods were used to verify the memory switching characteristics of the fabricated device. The charge transfer between ferredoxin protein molecules and Au electrode enables a bi-stable electrical conductivity allowing the system to be used as a digital memory device. Data storage is achieved by applying redox voltages which are within the range of -500 mV. These results suggest that the proposed device has a function of memory and can be used for the construction of a nano-scale bioelectronic device.

  19. Water-assisted proton transfer in ferredoxin I.

    PubMed

    Lutz, Stephan; Tubert-Brohman, Ivan; Yang, Yonggang; Meuwly, Markus

    2011-07-08

    The role of water molecules in assisting proton transfer (PT) is investigated for the proton-pumping protein ferredoxin I (FdI) from Azotobacter vinelandii. It was shown previously that individual water molecules can stabilize between Asp(15) and the buried [3Fe-4S](0) cluster and thus can potentially act as a proton relay in transferring H(+) from the protein to the μ(2) sulfur atom. Here, we generalize molecular mechanics with proton transfer to studying proton transfer reactions in the condensed phase. Both umbrella sampling simulations and electronic structure calculations suggest that the PT Asp(15)-COOH + H(2)O + [3Fe-4S](0) → Asp(15)-COO(-) + H(2)O + [3Fe-4S](0) H(+) is concerted, and no stable intermediate hydronium ion (H(3)O(+)) is expected. The free energy difference of 11.7 kcal/mol for the forward reaction is in good agreement with the experimental value (13.3 kcal/mol). For the reverse reaction (Asp(15)-COO(-) + H(2)O + [3Fe-4S](0)H(+) → Asp(15)-COOH + H(2)O + [3Fe-4S](0)), a larger barrier than for the forward reaction is correctly predicted, but it is quantitatively overestimated (23.1 kcal/mol from simulations versus 14.1 from experiment). Possible reasons for this discrepancy are discussed. Compared with the water-assisted process (ΔE ≈ 10 kcal/mol), water-unassisted proton transfer yields a considerably higher barrier of ΔE ≈ 35 kcal/mol.

  20. Ferredoxin:NAD + Oxidoreductase of Thermoanaerobacterium saccharolyticum and Its Role in Ethanol Formation

    DOE PAGES

    Tian, Liang; Lo, Jonathan; Shao, Xiongjun; ...

    2016-09-30

    Ferredoxin:NAD+oxidoreductase (NADH-FNOR) catalyzes the transfer of electrons from reduced ferredoxin to NAD+. This enzyme has been hypothesized to be the main enzyme responsible for ferredoxin oxidization in the NADH-based ethanol pathway inThermoanaerobacterium saccharolyticum; however, the corresponding gene has not yet been identified. Here, we identified the Tsac_1705 protein as a candidate FNOR based on the homology of its functional domains. We then confirmed its activityin vitrowith a ferredoxin-based FNOR assay. To determine its role in metabolism, thetsac_1705gene was deleted in different strains ofT. saccharolyticum. In wild-typeT. saccharolyticum, deletion oftsac_1705resulted in a 75% loss of NADH-FNOR activity, which indicated thatmore » Tsac_1705 is the main NADH-FNOR inT.saccharolyticum. When both NADH- and NADPH-linked FNOR genes were deleted, the ethanol titer decreased and the ratio of ethanol to acetate approached unity, indicative of the absence of FNOR activity. Finally, we tested the effect of heterologous expression of Tsac_1705 inClostridium thermocellumand found improvements in both the titer and the yield of ethanol. IMPORTANCERedox balance plays a crucial role in many metabolic engineering strategies. Ferredoxins are widely used as electron carriers for anaerobic microorganism and plants. This study identified the gene responsible for electron transfer from ferredoxin to NAD+, a key reaction in the ethanol production pathway of this organism and many other metabolic pathways. Identification of this gene is an important step in transferring the ethanol production ability of this organism to other organisms.« less

  1. Endocranial volume of Australopithecus africanus: new CT-based estimates and the effects of missing data and small sample size.

    PubMed

    Neubauer, Simon; Gunz, Philipp; Weber, Gerhard W; Hublin, Jean-Jacques

    2012-04-01

    Estimation of endocranial volume in Australopithecus africanus is important in interpreting early hominin brain evolution. However, the number of individuals available for investigation is limited and most of these fossils are, to some degree, incomplete and/or distorted. Uncertainties of the required reconstruction ('missing data uncertainty') and the small sample size ('small sample uncertainty') both potentially bias estimates of the average and within-group variation of endocranial volume in A. africanus. We used CT scans, electronic preparation (segmentation), mirror-imaging and semilandmark-based geometric morphometrics to generate and reconstruct complete endocasts for Sts 5, Sts 60, Sts 71, StW 505, MLD 37/38, and Taung, and measured their endocranial volumes (EV). To get a sense of the reliability of these new EV estimates, we then used simulations based on samples of chimpanzees and humans to: (a) test the accuracy of our approach, (b) assess missing data uncertainty, and (c) appraise small sample uncertainty. Incorporating missing data uncertainty of the five adult individuals, A. africanus was found to have an average adult endocranial volume of 454-461 ml with a standard deviation of 66-75 ml. EV estimates for the juvenile Taung individual range from 402 to 407 ml. Our simulations show that missing data uncertainty is small given the missing portions of the investigated fossils, but that small sample sizes are problematic for estimating species average EV. It is important to take these uncertainties into account when different fossil groups are being compared.

  2. Metal-ion-center assembly of ferredoxin and plastocyanin in isolated chloroplasts

    SciTech Connect

    Li, Hsoumin; Theg, S.M.; Bauerle, C.M.; Keegstra, K. )

    1990-09-01

    Most chloroplastic proteins are cytosolically synthesized andposttranslationally transported to their proper locations. Two examples of this group of proteins are ferredoxin and plastocyanin, both of which are metal-containing components of the photosynthetic electron-transport chain. The import process for these two proteins includes the insertion of the metal ions to produce the holo forms of the proteins. The authors show here that in vitro translated precursor proteins of ferredoxin and plastocyanin are synthesized as apo forms and are assembled into their respective holo forms after being imported into isolated chloroplasts. They also provide evidence that only mature-sized proteins are competent to be assembled into holo forms.

  3. The end of the line: can ferredoxin and ferredoxin NADP(H) oxidoreductase determine the fate of photosynthetic electrons?

    PubMed

    Goss, Tatjana; Hanke, Guy

    2014-01-01

    At the end of the linear photosynthetic electron transfer (PET) chain, the small soluble protein ferredoxin (Fd) transfers electrons to Fd:NADP(H) oxidoreductase (FNR), which can then reduce NADP+ to support C assimilation. In addition to this linear electron flow (LEF), Fd is also thought to mediate electron flow back to the membrane complexes by different cyclic electron flow (CEF) pathways: either antimycin A sensitive, NAD(P)H complex dependent, or through FNR located at the cytochrome b6f complex. Both Fd and FNR are present in higher plant genomes as multiple gene copies, and it is now known that specific Fd iso-proteins can promote CEF. In addition, FNR iso-proteins vary in their ability to dynamically interact with thylakoid membrane complexes, and it has been suggested that this may also play a role in CEF. We will highlight work on the different Fd-isoproteins and FNR-membrane association found in the bundle sheath (BSC) and mesophyll (MC) cell chloroplasts of the C4 plant maize. These two cell types perform predominantly CEF and LEF, and the properties and activities of Fd and FNR in the BSC and MC are therefore specialized for CEF and LEF respectively. A diversity of Fd isoproteins and dynamic FNR location has also been recorded in C3 plants, algae and cyanobacteria. This indicates that the principles learned from the extreme electron transport situations in the BSC and MC of maize might be usefully applied to understanding the dynamic transition between these states in other systems.

  4. The End of the Line: Can Ferredoxin and Ferredoxin NADP(H) Oxidoreductase Determine the Fate of Photosynthetic Electrons?

    PubMed Central

    Goss, Tatjana; Hanke, Guy

    2014-01-01

    At the end of the linear photosynthetic electron transfer (PET) chain, the small soluble protein ferredoxin (Fd) transfers electrons to Fd:NADP(H) oxidoreductase (FNR), which can then reduce NADP+ to support C assimilation. In addition to this linear electron flow (LEF), Fd is also thought to mediate electron flow back to the membrane complexes by different cyclic electron flow (CEF) pathways: either antimycin A sensitive, NAD(P)H complex dependent, or through FNR located at the cytochrome b6f complex. Both Fd and FNR are present in higher plant genomes as multiple gene copies, and it is now known that specific Fd iso-proteins can promote CEF. In addition, FNR iso-proteins vary in their ability to dynamically interact with thylakoid membrane complexes, and it has been suggested that this may also play a role in CEF. We will highlight work on the different Fd-isoproteins and FNR-membrane association found in the bundle sheath (BSC) and mesophyll (MC) cell chloroplasts of the C4 plant maize. These two cell types perform predominantly CEF and LEF, and the properties and activities of Fd and FNR in the BSC and MC are therefore specialized for CEF and LEF respectively. A diversity of Fd isoproteins and dynamic FNR location has also been recorded in C3 plants, algae and cyanobacteria. This indicates that the principles learned from the extreme electron transport situations in the BSC and MC of maize might be usefully applied to understanding the dynamic transition between these states in other systems. PMID:24678667

  5. Phenetic and functional analyses of the distal ulna of Australopithecus afarensis and Australopithecus africanus.

    PubMed

    Tallman, Melissa

    2015-01-01

    The morphology of the distal portion of the hominoid ulna is poorly studied despite its important functional role at the wrist joint. There are five qualitatively well-described fossil hominin distal ulnae belonging to Australopithecus afarensis and Australopithecus africanus, but there have been few efforts to quantify their morphology or relate it to their functional abilities. This article presents an effort to do so, using three-dimensional geometric morphometrics to analyze the shape of the distal ulna of the Plio-Pleistocene hominins and an extant comparative sample of great apes and humans. For the extant taxa, results show that the morphology of Pan and Pongo is distinct from that of Homo, and that these differences are likely related to climbing, clambering and below-branch suspension in the former, and the release of the limbs from locomotion and (potentially) tool manufacture in the latter. For the australopiths, results indicate that the A. afarensis sample is relatively heterogeneous. These results are driven by the morphology of A.L. 333-12, which is the largest ulna in the sample and has a unique combination of traits when compared with the other two A. afarensis specimens. Overall, the morphology of all the hominins was most consistent with the pattern displayed by extant great apes, and specifically Pan and Pongo; however, large overlap in shape in the distal ulna in the extant sample indicates that other areas of the skeleton may be more informative for functional analyses.

  6. Effects of Decompression Treatment for Controlling the Powderpost Beetle, Lyctus africanus Lesne, (Coleoptera: Lyctinae)

    PubMed Central

    Nakai, Kazushi; Hiraku, Tatsuya; Fujimoto, Izumi; Yoshimura, Tsuyoshi

    2016-01-01

    The efficacy of decompression treatment as a non-destructive method to control larvae of the powderpost beetle, Lyctus africanus Lesne, was evaluated in the laboratory using various combinations of two pressure levels, 1.1 kPa and 40 kPa, and three temperature levels, 20, 25, and 40 °C. Larval mortality generally depended on weight reduction while decreases in the oxygen level had relatively little effect. The lower pressure, 1.1 kPa, significantly affected mortality, and no larvae survived after 12 h of this pressure treatment, at 25 °C. The average body weight was reduced with treatment time and temperature, and the reduction rate at 25 °C was higher than that at the lower temperature, 20 °C. Effects on larvae of the higher pressure treatment, 40 kPa, with a CO2 gas purge, were tested to determine the feasibility of decompression treatment in the manufacturing process. Although higher pressure resulted in low mortality, the body weight was dramatically decreased using the CO2 purge. These results present important information on the possibility of using decompression treatment for wood products. PMID:27429007

  7. Enamel-dentine junction (EDJ) morphology distinguishes the lower molars of Australopithecus africanus and Paranthropus robustus.

    PubMed

    Skinner, Matthew M; Gunz, Philipp; Wood, Bernard A; Hublin, Jean-Jacques

    2008-12-01

    Tooth crown morphology plays a central role in hominin systematics, but the removal of the original outer enamel surface by dental attrition often eliminates from consideration the type of detailed crown morphology that has been shown to discriminate among hominin taxa. This reduces the size of samples available for study. The enamel-dentine junction (EDJ) is the developmental precursor and primary contributor to the morphology of the unworn outer enamel surface, and its morphology is only affected after considerable attrition. In this paper, we explore whether the form of the EDJ can be used to distinguish between the mandibular molars of two southern African fossil hominins: Paranthropus (or Australopithecus) robustus and Australopithecus africanus. After micro-computed tomographic scanning the molar sample, we made high-resolution images of the EDJ and used geometric morphometrics to compare EDJ shape differences between species, in addition to documenting metameric variation along the molar row within each species. Landmarks were collected along the marginal ridge that runs between adjacent dentine horns and around the circumference of the cervix. Our results suggest that the morphology of the EDJ can distinguish lower molars of these southern African hominins, and it can discriminate first, second, and third molars within each taxon. These results confirm previous findings that the EDJ preserves taxonomically valuable shape information in worn teeth. Mean differences in EDJ shape, in particular dentine horn height, crown height, and cervix shape, are more marked between adjacent molars within each taxon than for the same molar between the two taxa.

  8. Genome mining in Amycolatopsis balhimycina for ferredoxins capable of supporting cytochrome P450 enzymes involved in glycopeptide antibiotic biosynthesis.

    PubMed

    Geib, Nina; Weber, Tilmann; Wörtz, Tanja; Zerbe, Katja; Wohlleben, Wolfgang; Robinson, John A

    2010-05-01

    Ferredoxins are required to supply electrons to the cytochrome P450 enzymes involved in cross-linking reactions during the biosynthesis of the glycopeptide antibiotics balhimycin and vancomycin. However, the biosynthetic gene clusters for these antibiotics contain no ferredoxin- or ferredoxin reductase-like genes. In a search for potential ferredoxin partners for these P450s, here, we report an in silico analysis of the draft genome sequence of the balhimycin producer Amycolatopsis balhimycina, which revealed 11 putative Fe-S-containing ferredoxin genes. We show that two members (balFd-V and balFd-VII), produced as native-like holo-[3Fe-4S] ferredoxins in Escherichia coli, could supply electrons to the P450 OxyB (CYP165B) from both A. balhimycina and the vancomycin producer Amycolatopsis orientalis, and support in vitro turnover of peptidyl carrier protein-bound peptide substrates into monocyclic cross-linked products. These results show that ferredoxins encoded in the antibiotic-producing strain can act in a degenerate manner in supporting the catalytic functions of glycopeptide biosynthetic P450 enzymes from the same as well as heterologous gene clusters.

  9. Identification of Esters as Novel Aggregation Pheromone Components Produced by the Male Powder-Post Beetle, Lyctus africanus Lesne (Coleoptera: Lyctinae).

    PubMed

    Kartika, Titik; Shimizu, Nobuhiro; Yoshimura, Tsuyoshi

    2015-01-01

    Lyctus africanus is a cosmopolitan powder-post beetle that is considered one of the major pests threatening timber and timber products. Because infestations of this beetle are inconspicuous, damage is difficult to detect and identification is often delayed. We identified the chemical compounds involved in the aggregation behavior of L. africanus using preparations of crude hexanic extracts from male and female beetles (ME and FE, respectively). Both male and female beetles showed significant preferences for ME, which was found to contain three esters. FE was ignored by both the sexes. Further bioassay confirmed the role of esters in the aggregation behavior of L. africanus. Three esters were identified as 2-propyl dodecanoate, 3-pentyl dodecanoate, and 3-pentyl tetradecanoate. Further behavioral bioassays revealed 3-pentyl dodecanoate to play the main role in the aggregation behavior of female L. africanus beetles. However, significantly more beetles aggregated on a paper disk treated with a blend of the three esters than on a paper disk treated with a single ester. This is the first report on pheromone identification in L. africanus; in addition, the study for the first time presents 3-pentyl dodecanoate as an insect pheromone.

  10. Identification of Esters as Novel Aggregation Pheromone Components Produced by the Male Powder-Post Beetle, Lyctus africanus Lesne (Coleoptera: Lyctinae)

    PubMed Central

    2015-01-01

    Lyctus africanus is a cosmopolitan powder-post beetle that is considered one of the major pests threatening timber and timber products. Because infestations of this beetle are inconspicuous, damage is difficult to detect and identification is often delayed. We identified the chemical compounds involved in the aggregation behavior of L. africanus using preparations of crude hexanic extracts from male and female beetles (ME and FE, respectively). Both male and female beetles showed significant preferences for ME, which was found to contain three esters. FE was ignored by both the sexes. Further bioassay confirmed the role of esters in the aggregation behavior of L. africanus. Three esters were identified as 2-propyl dodecanoate, 3-pentyl dodecanoate, and 3-pentyl tetradecanoate. Further behavioral bioassays revealed 3-pentyl dodecanoate to play the main role in the aggregation behavior of female L. africanus beetles. However, significantly more beetles aggregated on a paper disk treated with a blend of the three esters than on a paper disk treated with a single ester. This is the first report on pheromone identification in L. africanus; in addition, the study for the first time presents 3-pentyl dodecanoate as an insect pheromone. PMID:26544984

  11. Ferredoxin and Formyltetrahydrofolate Synthetase: Comparative Studies with Clostridium acidiurici, Clostridium cylindrosporum, and Newly Isolated Anaerobic Uric Acid-Fermenting Strains

    PubMed Central

    Champion, Alexander B.; Rabinowitz, Jesse C.

    1977-01-01

    Six strains of Clostridium acidiurici and three strains of C. cylindrosporum were isolated from soil samples by enrichment culture with uric acid as the source of carbon, nitrogen, and energy. The newly isolated strains were characterized by their spore morphology and the amounts of glycine and formate formed by the fermentation of uric acid. The strains were easily identified as belonging to one species or the other on the basis of spore morphology and formate production. The crystal properties and spectra of the native ferredoxins of all the strains isolated and the amino acid composition and partial carboxy-terminal sequence of all their apoferredoxins were determined. All the ferredoxins were tested for cross-reactivity with antiserum to C. acidiurici ferredoxin by microcomplement fixation. Five of the six C. acidiurici strains, which had ferredoxins with amino acid compositions identical to that from C. acidiurici, also showed immunological identity (immunological distance = 0.0). These results suggest sequence identity. The one strain with a different amino acid composition failed to show complete cross-reactivity. Two of the three C. cylindrosporum strains have ferredoxin amino acid compositions identical to that from C. cylindrosporum. The third strain had a minimum of five differences in sequence. All C. cylindrosporum strains had ferredoxins that differed considerably from C. acidiurici strains (minimum of eight to nine differences), and none of these ferredoxins cross-reacted with antisera to C. acidiurici ferredoxin. Antisera were prepared to formyltetrahydrofolate synthetase from C. acidiurici and C. cylindrosporum, and all possible comparisons were made by using immunodiffusion and microcomplement fixation. There is more intraspecies variation in the synthetases than in the ferredoxins; however, the results suggest considerable interspecies differences in both proteins. These results suggest a low degree of genomic relatedness between the two species

  12. Are the differences between Stw 431 (Australopithecus africanus) and A.L. 288-1 (A. afarensis) significant?

    PubMed

    Dobson, Seth D

    2005-07-01

    Recent studies of early hominin body proportions paint a complex evolutionary picture, with multiple instances of reversal in body shape. These interpretations rest heavily upon the inferred limb joint proportions of Australopithecus africanus. For example, the partial skeleton Stw 431 has been suggested to show ape-like joint proportions compared to the A. afarensis specimen A.L. 288-1. This suggests an evolutionary reversal in the more recent A. africanus. However, no study has examined the probability of sampling the differences between Stw 431 and A.L. 288-1 from a single extant hominoid species. The present study compares elbow/hip and elbow/lumbosacral joint size ratios between Stw 431 and A.L. 288-1 using exact randomization, based on chimpanzee and human models of variation. Results indicate that differences in elbow/hip proportions between Stw 431 and A.L. 288-1 can be sampled from a single species. In contrast, differences in elbow/lumbosacral proportions between Stw 431 and A.L. 288-1 show a significantly low probability of being sampled from a single species. Thus, Stw 431 and A.L. 288-1 are not significantly different from each with regard to limb joint proportions, but Stw 431 has a significantly smaller lumbosacral joint. This pattern does not conform to previous interpretations of limb proportions in A. africanus. Low statistical power in the present study may account for the discrepancy. Further research is needed to illuminate the functional implications of variation in relative lumbosacral joint size in early hominins.

  13. The Afya Bora Consortium: an African-U.S. partnership to Train Leaders in Global Health

    PubMed Central

    Farquhar, Carey; Nathanson, Neal

    2011-01-01

    Synopsis The Afya Bora Consortium is a partnership of eight academic health institutions, four in Africa and four in the United States. The Consortium members have a history of collaboration in four African-U.S. pairs: Makerere University, Kampala, Uganda, and Johns Hopkins University, Baltimore, Maryland, USA; Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania, and the University of California in San Francisco, California, USA; the University of Botswana, Gaborone, Botswana, and the University of Pennsylvania, Philadelphia, Pennsylvania, USA; the University of Nairobi, Nairobi, Kenya, and the University of Washington, Seattle, Washington, USA. The Consortium is developing a Global Health Leadership Fellowship for medical, nursing, and public health professionals, largely drawn from the four African partner countries. The primary purpose of the fellowship is to provide trainees with practical skills that will prepare them for future positions leading the design, implementation and evaluation of large, high impact programs in governmental agencies, non-governmental organizations, and academic health institutions in their own countries. In this overview, we describe a Pilot of the proposed program, which includes three components: a six-week Core Curriculum taught in modules that focus on foundational skills in leadership, management, evaluation and other relevant topics; a six-month assignment to two Attachment Sites, that provides hands-on experience in a programmatic, clinical, or research area; and a post-training support and mentoring phase. We believe that the Afya Bora Fellowship is an innovative model, which, when fully implemented, could contribute significantly to training future leaders in global health and reducing “brain drain” of health professionals. PMID:21628054

  14. The natural endocast of Taung (Australopithecus africanus): insights from the unpublished papers of Raymond Arthur Dart.

    PubMed

    Falk, Dean

    2009-01-01

    Dart's 1925 announcement of Australopithecus africanus (Dart: Nature 115 [1925] 195-199) was highly controversial, partly because of an interpretation of the Taung natural endocast that rested on an erroneous identification of the lambdoid suture as the lunate sulcus. Unpublished materials from the University of Witwatersrand Archives (Dart, unpublished material) reveal that Dart reacted to the controversy by: 1) describing and illustrating the entire sulcal pattern on the Taung endocast, in contrast to just two sulcal identifications in 1925, 2) identifying a hypothetical part of the lambdoid suture and revising his description of the lunate sulcus, and 3) bolstering his argument that Taung's brain was advanced by detailing expansions in three significant cortical association areas. Four unpublished illustrations of Dart's identifications for sulci and sutures on the Taung endocast are compared here with those published by Keith (Keith: New discoveries relating to the antiquity of man (1931)), Schepers (Schepers: The endocranial casts of the South African ape-men. In: Broom R, Schepers GWH, editors. The South African fossil ape-men; the Australopithecinae [1946] p 155-272), and Falk (Falk: Am J Phys Anthropol 53 [1980] 525-539), and the thorny issue of the location of the lunate sulcus is revisited in light of new information. Archival materials reveal that Dart believed that Taung's brain was reorganized globally rather than in a mosaic manner, and that the shapes of certain cortical association areas showed that Australopithecus was closer to Pithecanthropus than to the living apes. Although a few of Dart's hitherto-unpublished sulcal identifications, including his revision for the lunate sulcus, were questionable, his claim that the Taung endocast reproduced a shape that was advanced toward a human condition in its prefrontal cortex and caudally protruded occipital lobe was correct.

  15. The ferredoxin-thioredoxin system of a green alga, Chlamydomonas reinhardtii: identification and characterization of thioredoxins and ferredoxin-thioredoxin reductase components

    NASA Technical Reports Server (NTRS)

    Huppe, H. C.; de Lamotte-Guery, F.; Buchanan, B. B.

    1990-01-01

    The components of the ferredoxin-thioredoxin (FT) system of Chlamydomonas reinhardtii have been purified and characterized. The system resembled that of higher plants in consisting of a ferredoxin-thioredoxin reductase (FTR) and two types of thioredoxin, a single f and two m species, m1 and m2. The Chlamydomonas m and f thioredoxins were antigenically similar to their higher-plant counterparts, but not to one another. The m thioredoxins were recognized by antibodies to both higher plant m and bacterial thioredoxins, whereas the thioredoxin f was not. Chlamydomonas thioredoxin f reacted, although weakly, with the antibody to spinach thioredoxin f. The algal thioredoxin f differed from thioredoxins studied previously in behaving as a basic protein on ion-exchange columns. Purification revealed that the algal thioredoxins had molecular masses (Mrs) typical of thioredoxins from other sources, m1 and m2 being 10700 and f 11500. Chlamydomonas FTR had two dissimilar subunits, a feature common to all FTRs studied thus far. One, the 13-kDa ("similar") subunit, resembled its counterpart from other sources in both size and antigenicity. The other, 10-kDa ("variable") subunit was not recognized by antibodies to any FTR tested. When combined with spinach, (Spinacia oleracea L.) thylakoid membranes, the components of the FT system functioned in the light activation of the standard target enzymes from chloroplasts, corn (Zea mays L.) NADP-malate dehydrogenase (EC 1.1.1.82) and spinach fructose 1,6-bisphosphatase (EC 3.1.3.11) as well as the chloroplast-type fructose 1,6-bisphosphatase from Chlamydomonas. Activity was greatest if ferredoxin and other components of the FT system were from Chlamydomonas. The capacity of the Chlamydomonas FT system to activate autologous FBPase indicates that light regulates the photosynthetic carbon metabolism of green algae as in other oxygenic photosynthetic organisms.

  16. A computational comparison of electron transfer from reduced ferredoxin to flavin adenine dinucleotide and a gold electrode.

    PubMed

    Walch, Stephen P; Komadina, Jason D; Prinz, Fritz B

    2009-05-21

    We have carried out calculations of the electronic structure of ferredoxin and of the electronic coupling matrix element Hif for electron transfer from reduced ferredoxin to flavin adenine dinucleotide (FAD) and to cluster models of the Au111 surface and a Au111 surface with a mercaptopyridene self-assembled monolayer (SAM). We conclude, based on Hif2, that a gold electrode is approximately 14 times less efficient as an electron acceptor than FAD and that the mercaptopyridine SAM enhances electron transfer. The magnitude of Hif is large enough for these systems that the weak coupling limit approximations may no longer be valid. However, the barrier to electron transfer in the strong coupling limit is computed to be small due to minimal geometry change between oxidized and reduced ferredoxin. MD simulations of the interaction of ferredoxin and protonated pyridine within a water solvation box indicate that the protonated pyridine does strongly orient the ferredoxin, favoring electron transfer as compared to a bare gold surface, where we speculate the orientation of the ferredoxin may be more random.

  17. Fhit interaction with ferredoxin reductase triggers generation of reactive oxygen species and apoptosis of cancer cells.

    PubMed

    Trapasso, Francesco; Pichiorri, Flavia; Gaspari, Marco; Palumbo, Tiziana; Aqeilan, Rami I; Gaudio, Eugenio; Okumura, Hiroshi; Iuliano, Rodolfo; Di Leva, Giampiero; Fabbri, Muller; Birk, David E; Raso, Cinzia; Green-Church, Kari; Spagnoli, Luigi G; Venuta, Salvatore; Huebner, Kay; Croce, Carlo M

    2008-05-16

    Fhit protein is lost in most cancers, its restoration suppresses tumorigenicity, and virus-mediated FHIT gene therapy induces apoptosis and suppresses tumors in preclinical models. We have used protein cross-linking and proteomics methods to characterize a Fhit protein complex involved in triggering Fhit-mediated apoptosis. The complex includes Hsp60 and Hsp10 that mediate Fhit stability and may affect import into mitochondria, where it interacts with ferredoxin reductase, responsible for transferring electrons from NADPH to cytochrome P450 via ferredoxin. Viral-mediated Fhit restoration increases production of intracellular reactive oxygen species, followed by increased apoptosis of lung cancer cells under oxidative stress conditions; conversely, Fhit-negative cells escape apoptosis, carrying serious oxidative DNA damage that may contribute to an increased mutation rate. Characterization of Fhit interacting proteins has identified direct effectors of the Fhit-mediated apoptotic pathway that is lost in most cancers through loss of Fhit.

  18. TWELVE ISOLATIONS OF ZIKA VIRUS FROM AEDES (STEGOMYIA) AFRICANUS (THEOBALD) TAKEN IN AND ABOVE A UGANDA FOREST.

    PubMed

    HADDOW, A J; WILLIAMS, M C; WOODALL, J P; SIMPSON, D I; GOMA, L K

    1964-01-01

    In continuation of a series of studies of arboreal mosquitos as virus vectors in Uganda, 12 strains of Zika virus and one strain of another Group B arbovirus were isolated between November 1961 and June 1963 from pools of Aedes (Stegomyia) africanus caught on a 120-foot (36.5-m) tower in Zika forest. For five strains it is known at what height the mosquitos were caught: one was from mosquitos taken at ground level, and the other four were from mosquitos taken in or above the upper canopy after sunset. No small mammal trapped in the forest either on the ground or in the trees showed serum antibody for Zika virus.These findings suggest that in Zika forest, A. (S.) africanus becomes infected from a virus reservoir that is probably not among the small animals tested and that infected mosquitos are liable to be spread widely beyond the forest by convection currents above the tree-tops in the first two or three hours after sunset.

  19. Premolar root and canal variation in South African Plio-Pleistocene specimens attributed to Australopithecus africanus and Paranthropus robustus.

    PubMed

    Moore, N Collin; Thackeray, J Francis; Hublin, Jean-Jacques; Skinner, Matthew M

    2016-04-01

    South African hominin fossils attributed to Australopithecus africanus derive from the cave sites of Makapansgat, Sterkfontein, and Taung, from deposits dated between about 2 and 3 million years ago (Ma), while Paranthropus robustus is known from Drimolen, Kromdraai, and Swartkrans, from deposits dated between about 1 and 2 Ma. Although variation in the premolar root complex has informed taxonomic and phylogenetic hypotheses for these fossil hominin species, traditionally there has been a focus on external root form, number, and position. In this study, we use microtomography to undertake the first comprehensive study of maxillary and mandibular premolar root and canal variation in Australopithecus africanus and Paranthropus robustus (n = 166 teeth) within and between the species. We also test for correlations between premolar size and root morphology as predicted under the 'size/number continuum' (SNC) model, which correlates increasing root number with tooth size. Our results demonstrate previously undocumented variation in these two fossil hominin species and highlight taxonomic differences in the presence and frequency of particular root types, qualitative root traits, and tooth size (measured as cervix cross-sectional area). Patterns of tooth size and canal/root number are broadly consistent with the SNC model, however statistically significant support is limited. The implications for hominin taxonomy in light of the increased variation in root morphology documented in this study are discussed.

  20. Atomic resolution modeling of the ferredoxin:[FeFe] hydrogenase complex from Chlamydomonas reinhardtii.

    PubMed

    Chang, Christopher H; King, Paul W; Ghirardi, Maria L; Kim, Kwiseon

    2007-11-01

    The [FeFe] hydrogenases HydA1 and HydA2 in the green alga Chlamydomonas reinhardtii catalyze the final reaction in a remarkable metabolic pathway allowing this photosynthetic organism to produce H(2) from water in the chloroplast. A [2Fe-2S] ferredoxin is a critical branch point in electron flow from Photosystem I toward a variety of metabolic fates, including proton reduction by hydrogenases. To better understand the binding determinants involved in ferredoxin:hydrogenase interactions, we have modeled Chlamydomonas PetF1 and HydA2 based on amino-acid sequence homology, and produced two promising electron-transfer model complexes by computational docking. To characterize these models, quantitative free energy calculations at atomic resolution were carried out, and detailed analysis of the interprotein interactions undertaken. The protein complex model we propose for ferredoxin:HydA2 interaction is energetically favored over the alternative candidate by 20 kcal/mol. This proposed model of the electron-transfer complex between PetF1 and HydA2 permits a more detailed view of the molecular events leading up to H(2) evolution, and suggests potential mutagenic strategies to modulate electron flow to HydA2.

  1. Structure of the bacterial plant-ferredoxin receptor FusA

    PubMed Central

    Grinter, Rhys; Josts, Inokentijs; Mosbahi, Khedidja; Roszak, Aleksander W.; Cogdell, Richard J.; Bonvin, Alexandre M. J. J.; Milner, Joel J.; Kelly, Sharon M.; Byron, Olwyn; Smith, Brian O.; Walker, Daniel

    2016-01-01

    Iron is a limiting nutrient in bacterial infection putting it at the centre of an evolutionary arms race between host and pathogen. Gram-negative bacteria utilize TonB-dependent outer membrane receptors to obtain iron during infection. These receptors acquire iron either in concert with soluble iron-scavenging siderophores or through direct interaction and extraction from host proteins. Characterization of these receptors provides invaluable insight into pathogenesis. However, only a subset of virulence-related TonB-dependent receptors have been currently described. Here we report the discovery of FusA, a new class of TonB-dependent receptor, which is utilized by phytopathogenic Pectobacterium spp. to obtain iron from plant ferredoxin. Through the crystal structure of FusA we show that binding of ferredoxin occurs through specialized extracellular loops that form extensive interactions with ferredoxin. The function of FusA and the presence of homologues in clinically important pathogens suggests that small iron-containing proteins represent an iron source for bacterial pathogens. PMID:27796364

  2. Coupling of ferredoxin and heterodisulfide reduction via electron bifurcation in hydrogenotrophic methanogenic archaea

    PubMed Central

    Kaster, Anne-Kristin; Moll, Johanna; Parey, Kristian; Thauer, Rudolf K.

    2011-01-01

    In methanogenic archaea growing on H2 and CO2 the first step in methanogenesis is the ferredoxin-dependent endergonic reduction of CO2 with H2 to formylmethanofuran and the last step is the exergonic reduction of the heterodisulfide CoM-S-S-CoB with H2 to coenzyme M (CoM-SH) and coenzyme B (CoB-SH). We recently proposed that in hydrogenotrophic methanogens the two reactions are energetically coupled via the cytoplasmic MvhADG/HdrABC complex. It is reported here that the purified complex from Methanothermobacter marburgensis catalyzes the CoM-S-S-CoB-dependent reduction of ferredoxin with H2. Per mole CoM-S-S-CoB added, 1 mol of ferredoxin (Fd) was reduced, indicating an electron bifurcation coupling mechanism: This stoichiometry of coupling is consistent with an ATP gain per mole methane from 4 H2 and CO2 of near 0.5 deduced from an H2-threshold concentration of 8 Pa and a growth yield of up to 3 g/mol methane. PMID:21262829

  3. Superoxide generated from the glutathione-mediated reduction of selenite damages the iron-sulfur cluster of chloroplastic ferredoxin.

    PubMed

    Fisher, Brian; Yarmolinsky, Dmitry; Abdel-Ghany, Salah; Pilon, Marinus; Pilon-Smits, Elizabeth A; Sagi, Moshe; Van Hoewyk, Doug

    2016-09-01

    Selenium assimilation in plants is facilitated by several enzymes that participate in the transport and assimilation of sulfate. Manipulation of genes that function in sulfur metabolism dramatically affects selenium toxicity and accumulation. However, it has been proposed that selenite is not reduced by sulfite reductase. Instead, selenite can be non-enzymatically reduced by glutathione, generating selenodiglutathione and superoxide. The damaging effects of superoxide on iron-sulfur clusters in cytosolic and mitochondrial proteins are well known. However, it is unknown if superoxide damages chloroplastic iron-sulfur proteins. The goals of this study were twofold: to determine whether decreased activity of sulfite reductase impacts selenium tolerance in Arabidopsis, and to determine if superoxide generated from the glutathione-mediated reduction of selenite damages the iron-sulfur cluster of ferredoxin. Our data demonstrate that knockdown of sulfite reductase in Arabidopsis does not affect selenite tolerance or selenium accumulation. Additionally, we provide in vitro evidence that the non-enzymatic reduction of selenite damages the iron-sulfur cluster of ferredoxin, a plastidial protein that is an essential component of the photosynthetic light reactions. Damage to ferredoxin's iron-sulfur cluster was associated with formation of apo-ferredoxin and impaired activity. We conclude that if superoxide damages iron-sulfur clusters of ferredoxin in planta, then it might contribute to photosynthetic impairment often associated with abiotic stress, including toxic levels of selenium.

  4. Biochemical Changes in Terminal Root Galls Caused by an Ectoparasitic Nematode, Longidorus africanus: Phenols, Carbohydrates and Cytokinins

    PubMed Central

    Epstein, E.

    1972-01-01

    Biochemical changes occurred in roots of bur marigold and grapevine infected with Longidorus africanus. Phenols of infected root tips differed quantitatively from those of healthy root tips (optical density of 0.68 and 0.32, respectively). Column chromatography of the phenol extracts resulted in more fractions in the infected than in the healthy root extract. Of the enzymes involved in phenol metabolism, three were tested. No polyphenol oxidase activity was detected and no difference in catalase activity was found between healthy and infected roots. Peroxidase activity, however, was much higher in infected roots. The extra peroxidase was associated mainly with the cortical cells of the infected root tips. Galled roots contained twice the amount of simple sugars and inulin as did the healthy roots. A cytokinin-active fraction was found only in the noninfected roots. PMID:19319273

  5. Primary Reactions of Photosynthesis: Photoreduction of a Bound Chloroplast Ferredoxin at Low Temperature as Detected by EPR Spectroscopy

    PubMed Central

    Malkin, R.; Bearden, Alan J.

    1971-01-01

    An electron paramagnetic resonance signal was observed at 25°K in whole spinach chloroplasts after illumination at 77°K. The light-induced epr spectrum had g-values (gx = 1.86, gy = 1.94, gz = 2.05) and a temperature dependence that were characteristic of the reduced state of a plant-type ferredoxin. The light-induced epr spectrum was also observed in broken spinach chloroplasts from which soluble ferredoxin was removed. Chemical analyses showed that both whole and broken spinach chloroplasts contained amounts of nonheme iron and “acid-labile sulfide” consistent with the presence of a bound iron-sulfur protein, at a level of about one molecule per 75 chlorophyll molecules. These results support the conclusion that chloroplasts contain a bound ferredoxin that may serve as a primary low-potential electron acceptor in photosynthesis. PMID:4322259

  6. Knockout of major leaf ferredoxin reveals new redox-regulatory adaptations in Arabidopsis thaliana.

    PubMed

    Voss, Ingo; Koelmann, Meike; Wojtera, Joanna; Holtgrefe, Simone; Kitzmann, Camillo; Backhausen, Jan E; Scheibe, Renate

    2008-07-01

    Ferredoxins are the major distributors for electrons to the various acceptor systems in plastids. In green tissues, ferredoxins are reduced by photosynthetic electron flow in the light, while in heterotrophic tissues, nicotinamide adenine dinucleotide (reduced) (NADPH) generated in the oxidative pentose-phosphate pathway (OPP) is the reductant. We have used a Ds-T-DNA insertion line of Arabidopsis thaliana for the gene encoding the major leaf ferredoxin (Fd2, At1g60950) to create a situation of high electron pressure in the thylakoids. Although these plants (Fd2-KO) possess only the minor fraction of leaf Fd1 (At1g10960), they grow photoautotrophically on soil, but with a lower growth rate and less chlorophyll. The more oxidized conditions in the stroma due to the formation of reactive oxygen species are causing a re-adjustment of the redox state in these plants that helps them to survive even under high light. Redox homeostasis is achieved by regulation at both, the post-translational and the transcriptional level. Over-reduction of the electron transport chain leads to increased transcription of the malate-valve enzyme NADP-malate dehydrogenase (MDH), and the oxidized stroma leads to an increased transcription of the OPP enzyme glucose-6-P dehydrogenase. In isolated spinach chloroplasts, oxidized conditions give rise to a decreased activation state of NADP-MDH and an activation of glucose-6-P dehydrogenase even in the light. In Fd2-KO plants, NADPH-requiring antioxidant systems are upregulated. These adjustments must be caused by plastid signals, and they prevent oxidative damage under rather severe conditions.

  7. Pyruvate ferredoxin oxidoreductase from the hyperthermophilic archaeon, Pyrococcus furiosus, functions as a CoA-dependent pyruvate decarboxylase.

    PubMed

    Ma, K; Hutchins, A; Sung, S J; Adams, M W

    1997-09-02

    Pyruvate ferredoxin oxidoreductase (POR) has been previously purified from the hyperthermophilic archaeon, Pyrococcus furiosus, an organism that grows optimally at 100 degrees C by fermenting carbohydrates and peptides. The enzyme contains thiamine pyrophosphate and catalyzes the oxidative decarboxylation of pyruvate to acetyl-CoA and CO2 and reduces P. furiosus ferredoxin. Here we show that this enzyme also catalyzes the formation of acetaldehyde from pyruvate in a CoA-dependent reaction. Desulfocoenzyme A substituted for CoA showing that the cofactor plays a structural rather than a catalytic role. Ferredoxin was not necessary for the pyruvate decarboxylase activity of POR, nor did it inhibit acetaldehyde production. The apparent Km values for CoA and pyruvate were 0.11 mM and 1.1 mM, respectively, and the optimal temperature for acetaldehyde formation was above 90 degrees C. These data are comparable to those previously determined for the pyruvate oxidation reaction of POR. At 80 degrees C (pH 8.0), the apparent Vm value for pyruvate decarboxylation was about 40% of the apparent Vm value for pyruvate oxidation rate (using P. furiosus ferredoxin as the electron acceptor). Tentative catalytic mechanisms for these two reactions are presented. In addition to POR, three other 2-keto acid ferredoxin oxidoreductases are involved in peptide fermentation by hyperthermophilic archaea. It is proposed that the various aldehydes produced by these oxidoreductases in vivo are used by two aldehyde-utilizing enzymes, alcohol dehydrogenase and aldehyde ferredoxin oxidoreductase, the physiological roles of which were previously unknown.

  8. A STD-NMR study of the interaction of the Anabaena ferredoxin-NADP+ reductase with the coenzyme.

    PubMed

    Antonini, Lara V; Peregrina, José R; Angulo, Jesús; Medina, Milagros; Nieto, Pedro M

    2014-01-07

    Ferredoxin-NADP+ reductase (FNR) catalyzes the electron transfer from ferredoxin to NADP+ via its flavin FAD cofactor. To get further insights in the architecture of the transient complexes produced during the hydride transfer event between the enzyme and the NADP+ coenzyme we have applied NMR spectroscopy using Saturation Transfer Difference (STD) techniques to analyze the interaction between FNRox and the oxidized state of its NADP+ coenzyme. We have found that STD NMR, together with the use of selected mutations on FNR and of the non-FNR reacting coenzyme analogue NAD+, are appropriate tools to provide further information about the the interaction epitope.

  9. The transient catalytically competent coenzyme allocation into the active site of Anabaena ferredoxin NADP+ -reductase.

    PubMed

    Peregrina, José Ramón; Lans, Isaías; Medina, Milagros

    2012-01-01

    Ferredoxin-NADP(+) reductase (FNR) catalyses the electron transfer from ferredoxin to NADP(+) via its flavin FAD cofactor. A molecular dynamics theoretical approach is applied here to visualise the transient catalytically competent interaction of Anabaena FNR with its coenzyme, NADP(+). The particular role of some of the residues identified as key in binding and accommodating the 2'P-AMP moiety of the coenzyme is confirmed in molecular terms. Simulations also indicate that the architecture of the active site precisely contributes to the orientation of the N5 of the FAD isoalloxazine ring and the C4 of the coenzyme nicotinamide ring in the conformation of the catalytically competent hydride transfer complex and, therefore, contributes to the efficiency of the process. In particular, the side chain of the C-terminal Y303 in Anabaena FNR appears key to providing the optimum geometry by reducing the stacking probability between the isoalloxazine and nicotinamide rings, thus providing the required co-linearity and distance among the N5 of the flavin cofactor, the C4 of the coenzyme nicotinamide and the hydride that has to be transferred between them. All these factors are highly related to the reaction efficiency, mechanism and reversibility of the process.

  10. Adrenodoxin: the archetype of vertebrate-type [2Fe-2S] cluster ferredoxins.

    PubMed

    Ewen, Kerstin Maria; Kleser, Michael; Bernhardt, Rita

    2011-01-01

    Adrenodoxin is probably the best characterized member of the vertebrate-type [2Fe-2S]-cluster ferredoxins. It has been in the spotlight of scientific interest for many years due to its essential role in mammalian steroid hormone biosynthesis, where it acts as electron mediator between the NADPH-dependent adrenodoxin reductase and several mitochondrial cytochromes P450. In this review we will focus on the present knowledge about protein-protein recognition in the mitochondrial cytochrome P450 system and the modulation of the electron transfer between Adx and its redox partners, AdR and CYP(s). We also intend to point out the potential biotechnological applications of Adx as a versatile electron donor to different cytochromes P450, both in vitro and in vivo. Finally we will address the comparison between the mammalian cytochrome P450-associated adrenodoxin and ferredoxins involved in iron-sulfur-cluster biosynthesis. Despite their different functions, these proteins display an amazing similarity regarding their primary sequence, tertiary structure and biophysical features.

  11. The bifunctional pyruvate decarboxylase/pyruvate ferredoxin oxidoreductase from Thermococcus guaymasensis.

    PubMed

    Eram, Mohammad S; Oduaran, Erica; Ma, Kesen

    2014-01-01

    The hyperthermophilic archaeon Thermococcus guaymasensis produces ethanol as a metabolic end product, and an alcohol dehydrogenase (ADH) catalyzing the reduction of acetaldehyde to ethanol has been purified and characterized. However, the enzyme catalyzing the formation of acetaldehyde has not been identified. In this study an enzyme catalyzing the production of acetaldehyde from pyruvate was purified and characterized from T. guaymasensis under strictly anaerobic conditions. The enzyme had both pyruvate decarboxylase (PDC) and pyruvate ferredoxin oxidoreductase (POR) activities. It was oxygen sensitive, and the optimal temperatures were 85°C and >95°C for the PDC and POR activities, respectively. The purified enzyme had activities of 3.8 ± 0.22 U mg(-1) and 20.2 ± 1.8 U mg(-1), with optimal pH-values of 9.5 and 8.4 for each activity, respectively. Coenzyme A was essential for both activities, although it did not serve as a substrate for the former. Enzyme kinetic parameters were determined separately for each activity. The purified enzyme was a heterotetramer. The sequences of the genes encoding the subunits of the bifunctional PDC/POR were determined. It is predicted that all hyperthermophilic β -keto acids ferredoxin oxidoreductases are bifunctional, catalyzing the activities of nonoxidative and oxidative decarboxylation of the corresponding β -keto acids.

  12. Ferredoxin:thioredoxin reductase (FTR) links the regulation of oxygenic photosynthesis to deeply rooted bacteria.

    PubMed

    Balsera, Monica; Uberegui, Estefania; Susanti, Dwi; Schmitz, Ruth A; Mukhopadhyay, Biswarup; Schürmann, Peter; Buchanan, Bob B

    2013-02-01

    Uncovered in studies on photosynthesis 35 years ago, redox regulation has been extended to all types of living cells. We understand a great deal about the occurrence, function, and mechanism of action of this mode of regulation, but we know little about its origin and its evolution. To help fill this gap, we have taken advantage of available genome sequences that make it possible to trace the phylogenetic roots of members of the system that was originally described for chloroplasts-ferredoxin, ferredoxin:thioredoxin reductase (FTR), and thioredoxin as well as target enzymes. The results suggest that: (1) the catalytic subunit, FTRc, originated in deeply rooted microaerophilic, chemoautotrophic bacteria where it appears to function in regulating CO(2) fixation by the reverse citric acid cycle; (2) FTRc was incorporated into oxygenic photosynthetic organisms without significant structural change except for addition of a variable subunit (FTRv) seemingly to protect the Fe-S cluster against oxygen; (3) new Trxs and target enzymes were systematically added as evolution proceeded from bacteria through the different types of oxygenic photosynthetic organisms; (4) an oxygenic type of regulation preceded classical light-dark regulation in the regulation of enzymes of CO(2) fixation by the Calvin-Benson cycle; (5) FTR is not universally present in oxygenic photosynthetic organisms, and in certain early representatives is seemingly functionally replaced by NADP-thioredoxin reductase; and (6) FTRc underwent structural diversification to meet the ecological needs of a variety of bacteria and archaea.

  13. The Subgenus Stegomyia of Aedes in the Afrotropical Region. 1. The Africanus Group of Species (Diptera: Culicidae) (Contributions of the American Entomological Institute. Volume 26, Number 1, 1990)

    DTIC Science & Technology

    1990-01-01

    the Central African Republic (Germain, Sureau et al., 1976). In addition to the yellow fever virus , Chikungunya, Zika and Bouboui viruses have been...In addition to yellow fever virus , Chikungunya, Zika and dengue 2 viruses have also been isolated from Ae. Zuteocephalus in Senegal (Cornet et al...Central African Republic. In addition to yellow fever virus , Chikungunya, Zika and Bouboui viruses have been isolated from Ae. africanus and Ae. opok

  14. Ferredoxin:NAD+ oxidoreductase of Thermoanaerobacterium saccharolyticum and its role in ethanol formation [Identification of a ferredoxin:NAD+ oxidoreductase of Thermoanaerobacterium saccharolyticum and its role in ethanol formation

    DOE PAGES

    Tian, Liang; Lo, Jonathan; Shao, Xiongjun; ...

    2016-09-30

    Ferredoxin:NAD+ oxidoreductase (NADH-FNOR) catalyzes the transfer of electrons from reduced ferredoxin to NAD+. This enzyme has been hypothesized to be the main enzyme responsible for ferredoxin oxidization in the NADH-based ethanol pathway in Thermoanaerobacterium saccharolyticum; however, the corresponding gene has not yet been identified. Here, we identified the Tsac_1705 protein as a candidate FNOR based on the homology of its functional domains. We then confirmed its activity in vitro with a ferredoxin-based FNOR assay. To determine its role in metabolism, the tsac_1705 gene was deleted in different strains of T. saccharolyticum. In wild-type T. saccharolyticum, deletion of tsac_1705 resulted inmore » a 75% loss of NADH-FNOR activity, which indicated that Tsac_1705 is the main NADH-FNOR in T. saccharolyticum. When both NADH- and NADPH-linked FNOR genes were deleted, the ethanol titer decreased and the ratio of ethanol to acetate approached unity, indicative of the absence of FNOR activity. As a result, we tested the effect of heterologous expression of Tsac_1705 in Clostridium thermocellum and found improvements in both the titer and the yield of ethanol.« less

  15. Insights into Flavin-based Electron Bifurcation via the NADH-dependent Reduced Ferredoxin:NADP Oxidoreductase Structure*

    PubMed Central

    Demmer, Julius K.; Huang, Haiyan; Wang, Shuning; Demmer, Ulrike; Thauer, Rudolf K.; Ermler, Ulrich

    2015-01-01

    NADH-dependent reduced ferredoxin:NADP oxidoreductase (NfnAB) is found in the cytoplasm of various anaerobic bacteria and archaea. The enzyme reversibly catalyzes the endergonic reduction of ferredoxin with NADPH driven by the exergonic transhydrogenation from NADPH onto NAD+. Coupling is most probably accomplished via the mechanism of flavin-based electron bifurcation. To understand this process on a structural basis, we heterologously produced the NfnAB complex of Thermotoga maritima in Escherichia coli, provided kinetic evidence for its bifurcating behavior, and determined its x-ray structure in the absence and presence of NADH. The structure of NfnAB reveals an electron transfer route including the FAD (a-FAD), the [2Fe-2S] cluster of NfnA and the FAD (b-FAD), and the two [4Fe-4S] clusters of NfnB. Ferredoxin is presumably docked onto NfnB close to the [4Fe-4S] cluster distal to b-FAD. NAD(H) binds to a-FAD and NADP(H) consequently to b-FAD, which is positioned in the center of the NfnAB complex and the site of electron bifurcation. Arg187 is hydrogen-bonded to N5 and O4 of the bifurcating b-FAD and might play a key role in adjusting a low redox potential of the FADH•/FAD pair required for ferredoxin reduction. A mechanism of FAD-coupled electron bifurcation by NfnAB is proposed. PMID:26139605

  16. Identification and cloning of two immunogenic Clostridium perfringens proteins, elongation factor Tu and pyruvate:ferredoxin oxidoreductase of C. perfringens

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Clostridium-related poultry diseases such as necrotic enteritis (NE) and gangrenous dermatitis (GD) cause substantial economic losses on a global scale. Two antigenic Clostridium perfringens proteins, elongation factor Tu (EF-Tu) and pyruvate:ferredoxin oxidoreductase (PFO), were identified by react...

  17. Purification and characterization of 2-oxoglutarate:ferredoxin oxidoreductase from a thermophilic, obligately chemolithoautotrophic bacterium, Hydrogenobacter thermophilus TK-6.

    PubMed Central

    Yoon, K S; Ishii, M; Igarashi, Y; Kodama, T

    1996-01-01

    2-Oxoglutarate:ferredoxin oxidoreductase from a thermophilic, obligately autotrophic, hydrogen-oxidizing bacterium, Hydrogenobacter thermophilus TK-6, was purified to homogeneity by precipitation with ammonium sulfate and by fractionation by DEAE-Sepharose CL-6B, polyacrylate-quaternary amine, hydroxyapatite, and Superdex-200 chromatography. The purified enzyme had a molecular mass of about 105 kDa and comprised two subunits (70 kDa and 35 kDa). The activity of the 2-oxoglutarate:ferredoxin oxidoreductase was detected by the use of 2-oxoglutarate, coenzyme A, and one of several electron acceptors in substrate amounts (ferredoxin isolated from H. thermophilus, flavin adenine dinucleotide, flavin mononucleotide, or methyl viologen). NAD, NADP, and ferredoxins from Chlorella spp. and Clostridium pasteurianum were ineffective. The enzyme was extremely thermostable; the temperature optimum for 2-oxoglutarate oxidation was above 80 degrees C, and the time for a 50% loss of activity at 70 degrees C under anaerobic conditions was 22 h. The optimum pH for a 2-oxoglutarate oxidation reaction was 7.6 to 7.8. The apparent Km values for 2-oxoglutarate and coenzyme A at 70 degrees C were 1.42 mM and 80 microM, respectively. PMID:8655524

  18. Evidence for the involvement of PSI-E subunit in the reduction of ferredoxin by photosystem I.

    PubMed

    Rousseau, F; Sétif, P; Lagoutte, B

    1993-05-01

    Of the stroma-accessible proteins of photosystem I (PSI) from Synechocystis sp. PCC 6803, the PSI-C, PSI-D and PSI-E subunits have already been characterized, and the corresponding genes isolated. PCR amplification and cassette mutagenesis were used in this work to delete the psaE gene. PSI particles were isolated from this mutant, which lacks subunit PSI-E, and the direct photoreduction of ferredoxin was investigated by flash absorption spectroscopy. The second order rate constant for reduction of ferredoxin by wild type PSI was estimated to be approximately 10(9) M-1s-1. Relative to the wild type, PSI lacking PSI-E exhibited a rate of ferredoxin reduction decreased by a factor of at least 25. After reassociation of the purified PSI-E polypeptide, the original rate of electron transfer was recovered. When a similar reconstitution was performed with a PSI-E polypeptide from spinach, an intermediate rate of reduction was observed. Membrane labeling of the native PSI with fluorescein isothiocyanate allowed the isolation of a fluorescent PSI-E subunit. Peptide analysis showed that some residues following the N-terminal sequence were labeled and thus probably accessible to the stroma, whereas both N- and C-terminal ends were probably buried in the photosystem I complex. Site-directed mutagenesis based on these observations confirmed that important changes in either of the two terminal sequences of the polypeptide impaired its correct integration in PSI, leading to phenotypes identical to the deleted mutant. Less drastic modifications in the predicted stroma exposed sequences did not impair PSI-E integration, and the ferredoxin photoreduction was not significantly affected. All these results lead us to propose a structural role for PSI-E in the correct organization of the site involved in ferredoxin photoreduction.

  19. A Highly Stable Plastidic-Type Ferredoxin-NADP(H) Reductase in the Pathogenic Bacterium Leptospira interrogans

    PubMed Central

    Catalano-Dupuy, Daniela L.; Musumeci, Matías A.; López-Rivero, Arleth; Ceccarelli, Eduardo A.

    2011-01-01

    Leptospira interrogans is a bacterium that is capable of infecting animals and humans, and its infection causes leptospirosis with a range of symptoms from flu-like to severe illness and death. Despite being a bacteria, Leptospira interrogans contains a plastidic class ferredoxin-NADP(H) reductase (FNR) with high catalytic efficiency, at difference from the bacterial class FNRs. These flavoenzymes catalyze the electron transfer between NADP(H) and ferredoxins or flavodoxins. The inclusion of a plastidic FNR in Leptospira metabolism and in its parasitic life cycle is not currently understood. Bioinformatic analyses of the available genomic and proteins sequences showed that the presence of this enzyme in nonphotosynthetic bacteria is restricted to the Leptospira genus and that a [4Fe-4S] ferredoxin (LB107) encoded by the Leptospira genome may be the natural substrate of the enzyme. Leptospira FNR (LepFNR) displayed high diaphorase activity using artificial acceptors and functioned as a ferric reductase. LepFNR displayed cytochrome c reductase activity with the Leptospira LB107 ferredoxin with an optimum at pH 6.5. Structural stability analysis demonstrates that LepFNR is one of the most stable FNRs analyzed to date. The persistence of a native folded LepFNR structure was detected in up to 6 M urea, a condition in which the enzyme retains 38% activity. In silico analysis indicates that the high LepFNR stability might be due to robust interactions between the FAD and the NADP+ domains of the protein. The limited bacterial distribution of plastidic class FNRs and the biochemical and structural properties of LepFNR emphasize the uniqueness of this enzyme in the Leptospira metabolism. Our studies show that in L. interrogans a plastidic-type FNR exchanges electrons with a bacterial-type ferredoxin, process which has not been previously observed in nature. PMID:22039544

  20. The crystal structure of NADPH:ferredoxin reductase from Azotobacter vinelandii.

    PubMed Central

    Sridhar Prasad, G.; Kresge, N.; Muhlberg, A. B.; Shaw, A.; Jung, Y. S.; Burgess, B. K.; Stout, C. D.

    1998-01-01

    NADPH:ferredoxin reductase (AvFPR) is involved in the response to oxidative stress in Azotobacter vinelandii. The crystal structure of AvFPR has been determined at 2.0 A resolution. The polypeptide fold is homologous with six other oxidoreductases whose structures have been solved including Escherichia coli flavodoxin reductase (EcFldR) and spinach, and Anabaena ferredoxin:NADP+ reductases (FNR). AvFPR is overall most homologous to EcFldR. The structure is comprised of a N-terminal six-stranded antiparallel beta-barrel domain, which binds FAD, and a C-terminal five-stranded parallel beta-sheet domain, which binds NADPH/NADP+ and has a classical nucleotide binding fold. The two domains associate to form a deep cleft where the NADPH and FAD binding sites are juxtaposed. The structure displays sequence conserved motifs in the region surrounding the two dinucleotide binding sites, which are characteristic of the homologous enzymes. The folded over conformation of FAD in AvFPR is similar to that in EcFldR due to stacking of Phe255 on the adenine ring of FAD, but it differs from that in the FNR enzymes, which lack a homologous aromatic residue. The structure of AvFPR displays three unique features in the environment of the bound FAD. Two features may affect the rate of reduction of FAD: the absence of an aromatic residue stacked on the isoalloxazine ring in the NADPH binding site; and the interaction of a carbonyl group with N10 of the flavin. Both of these features are due to the substitution of a conserved C-terminal tyrosine residue with alanine (Ala254) in AvFPR. An additional unique feature may affect the interaction of AvFPR with its redox partner ferredoxin I (FdI). This is the extension of the C-terminus by three residues relative to EcFldR and by four residues relative to FNR. The C-terminal residue, Lys258, interacts with the AMP phosphate of FAD. Consequently, both phosphate groups are paired with a basic group due to the simultaneous interaction of the FMN

  1. Reproductive functional anatomy and oestrous cycle pattern of the female brush-tailed porcupine (Atherurus africanus, Gray 1842) from Gabon.

    PubMed

    Mayor, P; López-Béjar, M; Jori, F; Fenech, M; López-Gatius, F

    2003-07-15

    In the present study, we examined certain features of the functional anatomy of the female genital tract of the wild brush-tailed porcupine (Atherurus africanus) to obtain data on the reproductive biology of this African forest rodent. Two consecutive experiments were performed. The aim of the first was to establish macroscopic and microscopic features of the genital organs, and to explore correlations between predominant ovarian structures and vaginal contents in 20 wild, mature females. In the second experiment, we inspected the external genitalia and vaginal smears of a further 10 females in captivity on a daily basis for 90 days. The uterus of the brush-tailed porcupine is bicornuate and composed of two separated uterine horns, a uterine body and cervix. The genital tract does not present a vaginal vestibule. Thus, there is no portion common to genital and urinary tracts. Females in the follicular phase of the oestrous cycle showed increased cornification of the vaginal epithelium and a high density of eosinophilic cells in vaginal smears. The vulva and vaginal opening were open, reddish and tumefacted. In luteal phase or in pregnancy, epithelial cornification and eosinophilic features were notably reduced and the vagina presented a pale, non-tumefacted vulva and a vaginal closure membrane. Females in captivity showed spontaneous cycles, a polyoestrous reproduction pattern and, based on features of the external genitalia and vaginal smears, their oestrous cycle length was 27.1+/-6.4 days (n=12).

  2. Carbofuran and its toxic metabolites provide forensic evidence for furadan exposure in vultures (Gyps africanus) in Kenya.

    PubMed

    Otieno, Peter O; Lalah, Joseph O; Virani, Munir; Jondiko, Isaac O; Schramm, Karl-Werner

    2010-05-01

    Forensic analysis of carbofuran residues in weathered tissue samples for evidence of Furadan exposure in vultures (Gps africanus) by HPLC gave concentration (mg/Kg dry tissue weight) ranges of bdl - 0.07 (carbofuran), bdl - 0.499 (3-ketocarbofuran) and 0.013-0.147 (3-hydroxycarbofuran) in beaks, bdl-0.65 (carbofuran), 0.024-0.190 (3-ketocarbofuran) and 0.017-0.098 (3-hydroxycarbofuran) in feet, 0.179-0.219 (3-ketocarbofuran) and 0.081-0.093 (3-hydroxycarbofuran) in crop content, 0.078-0.082 (3-ketocarbofuran) and 0.091-0.101 (3-hydroxycarbofuran) in muscle of a laced carcass and 0.006-0.014 (carbofuran), 0.590-1.010 (3-ketocarbofuran) and 0.095-0.135 (3-hydroxycarbofuran) in soil sampled from a poisoning site. These compounds were confirmed by GC-MS. The results showed that HPLC combined with GC-MS is suitable for forensic analysis of carbofuran residues in bird tissue samples and that forensic investigation should include its two toxic metabolites, 3-hydroxycarbofuran and 3-ketocarbofuran.

  3. Tiarajudens eccentricus and Anomocephalus africanus, two bizarre anomodonts (Synapsida, Therapsida) with dental occlusion from the Permian of Gondwana

    PubMed Central

    Cisneros, Juan Carlos; Abdala, Fernando; Jashashvili, Tea; de Oliveira Bueno, Ana; Dentzien-Dias, Paula

    2015-01-01

    Anomodontia was a highly successful tetrapod clade during the Permian and the Triassic. New morphological information regarding two bizarre basal anomodonts is provided and their palaeoecological significance is explored. The osteology of the recently discovered Tiarajudens eccentricus Cisneros et al. 2011, from the Brazilian Permian, is described in detail. The taxon exhibits unusual postcranial features, including the presence of gastralia. Additional preparation and computed tomography scans of the holotype of Anomocephalus africanus Modesto et al. 1999 discovered in the Karoo Basin of South Africa allow a reappraisal of this genus. Anomocephalus is similar to Tiarajudens with regard to several traits, including a battery of large, transversally expanded, palatal teeth. Molariform teeth are present in the mandible of the African taxon, providing additional insight into the function of the earliest tooth-occlusion mechanism known in therapsids. At least two waves of tooth replacement can be recognized in the palate of Anomocephalus. The outsized, blade-like caniniforms of the herbivorous Tiarajudens allow several non-exclusive ecological interpretations, among which we favour intraspecific display or combat. This behaviour was an alternative to the head-butting practised by the contemporary dinocephalians. Combat specializations that are considered typical of Cenozoic herbivores likely evolved during the Middle Permian, at the time the first communities with diverse, abundant tetrapod herbivores were being assembled. PMID:26587266

  4. The enamel-dentine junction in the postcanine dentition of Australopithecus africanus: intra-individual metameric and antimeric variation.

    PubMed

    Braga, J; Thackeray, J F; Subsol, G; Kahn, J L; Maret, D; Treil, J; Beck, A

    2010-01-01

    We used micro-computed tomography and virtual tools to study metric and morphological features at the enamel-dentine junction and on the outer enamel surface in the postcanine dentition of an exceptionally well-preserved maxilla and mandible of an early hominin. The fossil, Sts 52 from Sterkfontein, South Africa, is attributed to Australopithecus africanus and is about 2.5 million years old. For comparative purposes in this exploratory study, we also used micro-computed tomography to analyse the dentition of a common chimpanzee (Pan troglodytes), a pygmy chimpanzee (Pan paniscus) and three extant humans. Metameric variation of the 3D enamel-dentine junction in the two chimpanzee mandibles was much smaller than in extant humans. Variation in metameric shape was high and complex. Notably, the mandibular metameric variation in extant humans can be greater within individuals, as compared with variation between individuals, with differences in shape appearing greater for M2 compared with M1. We recommend the use of a new approach in which individual metameric variation is systematically assessed before making inferences about differences between fossil hominin species. The fossil hominin examined in this study showed a metameric pattern of mandibular variation in shape that was comparable to the pattern seen in two chimpanzees. This degree of metameric variation appeared relatively small compared with the much larger patterns of variation observed within and between extant humans.

  5. Continuous dental eruption identifies Sts 5 as the developmentally oldest fossil hominin and informs the taxonomy of Australopithecus africanus.

    PubMed

    Villmoare, B; Kuykendall, K; Rae, T C; Brimacombe, C S

    2013-12-01

    The relatively small Australopithecus africanus specimen Sts 5 has figured prominently in taxonomic debates, and the determination of this specimen as a young male or an elderly female has the potential to offer a great deal of resolution on this question. Sts 5 has been argued to be either a small, immature male or a mature female based on a variety of characters. A proposed model of continuous root remodeling and angular change for heavily worn dentition may account for the extremely short tooth roots, particularly for the anterior dentition, that Sts 5 demonstrates. The anterior tooth roots of Sts 5 are oriented vertically (relative to the alveolar plane), unlike those found in most other apes, humans, and fossil specimens, in which the tooth roots are roughly parallel with the plane of the nasoalveolar clivus. Computed tomography (CT) data of adult apes were examined and a relationship between the angle of the anterior tooth roots and their length was discovered, caused by heavily worn anterior dentition continuing to erupt to maintain occlusion. The extremely short and vertically oriented anterior roots observed in Sts 5 thus suggest that the specimen represents an aged female specimen with extremely worn dentition. Interestingly, this reorientation of anterior tooth roots helps account for the unusual nasoalveolar contour of Sts 5. The remodeling associated with the heavily worn teeth and reoriented roots thus resolves the taxonomic question raised by analyses identifying unusual prognathism of this small specimen.

  6. Molecular Dynamics Simulations of Trichomonas vaginalis Ferredoxin Show a Loop-Cap Transition

    SciTech Connect

    Weksberg, Tiffany E; Lynch, Gillian C; Krause, Kurt; Pettitt, Bernard M

    2007-05-01

    The crystal structure of the oxidized Trichomonas vaginalis ferredoxin (Tvfd) showed a unique crevice that exposed the redox center. Here we have examined the dynamics and solvation of the active site of Tvfd using molecular dynamics simulations of both the reduced and oxidized states. The oxidized simulation stays true to the crystal form with a heavy atom root mean-squared deviation of 2Å . However, within the reduced simulation of Tvfd a profound loop-cap transition into the redox center occurred within 6-ns of the start of the simulation and remained open throughout the rest of the 20-ns simulation. This large opening seen in the simulations supports the hypothesis that the exceptionally fast electron transfer rate between Tvfd and the drug metronidazole is due to the increased access of the antibiotic to the redox center of the protein and not due to the reduction potential.

  7. Molecular Dynamics Simulations of Trichomonas vaginalis Ferredoxin Show a Loop-Cap Transition.

    SciTech Connect

    Weksberg, Tiffany E; Lynch, Gillian C; Krause, Kurt; Pettitt, Bernard M

    2007-05-01

    The crystal structure of the oxidized Trichomonas vaginalis ferredoxin (Tvfd) showed a unique crevice that exposed the redox center. Here we have examined the dynamics and solvation of the active site of Tvfd using molecular dynamics simulations of both the reduced and oxidized states. The oxidized simulation stays true to the crystal form with a heavy atom root mean-squared deviation of 2Å. However, within the reduced simulation of Tvfd a profound loop-cap transition into the redox center occurred within 6-ns of the start of the simulation and remained open throughout the rest of the 20-ns simulation. This large opening seen in the simulations supports the hypothesis that the exceptionally fast electron transfer rate between Tvfd and the drug metronidazole is due to the increased access of the antibiotic to the redox center of the protein and not due to the reduction potential.

  8. Distribution of isoforms of ferredoxin-NADP(+) reductase (FNR) in cyanobacteria in two growth conditions.

    PubMed

    Alcántara-Sánchez, Felipe; Leyva-Castillo, Lourdes Elizabeth; Chagolla-López, Alicia; González de la Vara, Luis; Gómez-Lojero, Carlos

    2017-04-01

    Ferredoxin-NADP(+) reductase (FNR) transfers reducing equivalents between ferredoxin and NADP(H) in the photosynthetic electron transport chains of chloroplasts and cyanobacteria. In most cyanobacteria, FNR is coded by a single petH gene. The structure of FNR in photosynthetic organisms can be constituted by FAD-binding and NADPH-binding domains (FNR-2D), or by these and an additional N-terminal domain (FNR-3D). In this article, biochemical evidence is provided supporting the induction of FNR-2D by iron or combined nitrogen deficiency in the cyanobacteria Synechocystis PCC 6803 and Anabaena variabilis ATCC 29413. In cell extracts of these cyanobacteria, most of FNR was associated to phycobilisomes (PBS) or phycocyanin (PC), and the rest was found as free enzyme. Free FNR activity increased in both cyanobacteria under iron stress and during diazotrophic conditions in A. variabilis. Characterization of FNR from both cyanobacteria showed that the PBS-associated enzyme was FNR-3D and the free enzyme was mostly a FNR-2D isoform. Predominant isoforms in heterocysts of A. variabilis were FNR-2D; where its N-terminal sequence lacked an initial (formyl)methionine. This means that FNR-3D is targeted to thylakoid membrane, and anchored to PBS, and FNR-2D is found as a soluble protein in the cytoplasm, when iron or fixed nitrogen deficiencies prevail in the environment. Moreover, given that Synechocystis and Anabaena variabilis are dissimilar in genotype, phenotype and ecology, the presence of these two-domain proteins in these species suggests that the mechanism of FNR induction is common among cyanobacteria regardless of their habitat and morphotype.

  9. A Ferredoxin- and F420H2-Dependent, Electron-Bifurcating, Heterodisulfide Reductase with Homologs in the Domains Bacteria and Archaea

    PubMed Central

    Yan, Zhen

    2017-01-01

    ABSTRACT Heterodisulfide reductases (Hdr) of the HdrABC class are ancient enzymes and a component of the anaerobic core belonging to the prokaryotic common ancestor. The ancient origin is consistent with the widespread occurrence of genes encoding putative HdrABC homologs in metabolically diverse prokaryotes predicting diverse physiological functions; however, only one HdrABC has been characterized and that was from a narrow metabolic group of obligate CO2-reducing methanogenic anaerobes (methanogens) from the domain Archaea. Here we report the biochemical characterization of an HdrABC homolog (HdrA2B2C2) from the acetate-utilizing methanogen Methanosarcina acetivorans with unusual properties structurally and functionally distinct from the only other HdrABC characterized. Homologs of the HdrA2B2C2 archetype are present in phylogenetically and metabolically diverse species from the domains Bacteria and Archaea. The expression of the individual HdrA2, HdrB2, and HdrB2C2 enzymes in Escherichia coli, and reconstitution of an active HdrA2B2C2 complex, revealed an intersubunit electron transport pathway dependent on ferredoxin or coenzyme F420 (F420H2) as an electron donor. Remarkably, HdrA2B2C2 couples the previously unknown endergonic oxidation of F420H2 and reduction of ferredoxin with the exergonic oxidation of F420H2 and reduction of the heterodisulfide of coenzyme M and coenzyme B (CoMS-SCoB). The unique electron bifurcation predicts a role for HdrA2B2C2 in Fe(III)-dependent anaerobic methane oxidation (ANME) by M. acetivorans and uncultured species from ANME environments. HdrA2B2C2, ubiquitous in acetotrophic methanogens, was shown to participate in electron transfer during acetotrophic growth of M. acetivorans and proposed to be essential for growth in the environment when acetate is limiting. PMID:28174314

  10. Occurrence of ferredoxin:NAD+ oxidoreductase activity and its ion specificity in several Gram-positive and Gram-negative bacteria

    PubMed Central

    Hess, Verena; Gallegos, Rene; Jones, J Andrew; Barquera, Blanca; Malamy, Michael H

    2016-01-01

    A ferredoxin:NAD+ oxidoreductase was recently discovered as a redox-driven ion pump in the anaerobic, acetogenic bacterium Acetobacterium woodii. The enzyme is assumed to be encoded by the rnf genes. Since these genes are present in the genomes of many bacteria, we tested for ferredoxin:NAD+ oxidoreductase activity in cytoplasmic membranes from several different Gram-positive and Gram-negative bacteria that have annotated rnf genes. We found this activity in Clostridium tetanomorphum, Clostridium ljungdahlii, Bacteroides fragilis, and Vibrio cholerae but not in Escherichia coli and Rhodobacter capsulatus. As in A. woodii, the activity was Na+-dependent in C. tetanomorphum and B. fragilis but Na+-independent in C. ljungdahlii and V. cholerae. We deleted the rnf genes from B. fragilis and demonstrated that the mutant has greatly reduced ferredoxin:NAD+ oxidoreductase activity. This is the first genetic proof that the rnf genes indeed encode the reduced ferredoxin:NAD+ oxidoreductase activity. PMID:26793417

  11. Cloning, expression, and molecular characterization of the gene encoding an extremely thermostable [4Fe-4S] ferredoxin from the hyperthermophilic archaeon Pyrococcus furiosus.

    PubMed Central

    Heltzel, A; Smith, E T; Zhou, Z H; Blamey, J M; Adams, M W

    1994-01-01

    The gene for ferredoxin from the hyperthermophilic archaeon Pyrococcus furiosus was cloned, sequenced, and expressed in Escherichia coli. The coding region confirmed the determined amino acid sequence. Putative archaeon-type transcriptional regulatory elements were identified. The fdxA gene appears to be an independent transcriptional unit. Recombinant ferredoxin was indistinguishable from the protein purified from P. furiosus in its thermal stability and in the potentiometric and spectroscopic properties of its [4Fe-4S] cluster. PMID:8045914

  12. Characterization of the genome region encoding an fdxH-type ferredoxin and a new 2[4Fe-4S] ferredoxin from the nonheterocystous, nitrogen-fixing cyanobacterium Plectonema boryanum PCC 73110.

    PubMed Central

    Schrautemeier, B; Cassing, A; Böhme, H

    1994-01-01

    A genomic DNA region with four consecutive open reading frames, including an fdxH-type gene, has been sequenced and initially characterized for the nonheterocystous nitrogen-fixing cyanobacterium Plectonema boryanum PCC 73110. The fdxH gene encodes a [2Fe-2S]-type ferredoxin, 98 amino acids in length, with a deduced molecular mass of 10.9 kDa. Conserved residues include two characteristic lysines at positions 10 and 11, shown recently to be important for interaction with nitrogenase reductase (S. Schmitz, B. Schrautermeier, and H. Böhme, Mol. Gen. Genet. 240:455-460, 1993). The gene is transcribed only under anaerobic nitrogenase-inducing conditions, whereas the Plectonema petF gene, encoding a different (type 1) [2Fe-2S] ferredoxin, is only transcribed in cultures growing with combined nitrogen. The fdxH gene was expressed in Escherichia coli as a holoprotein. The purified protein was able to effectively donate electrons to cyanobacterial nitrogenase, whereas PetF from the same organism was not. The occurrence of FdxH in the nonheterocystous genus Plectonema demonstrates for the first time that FdxH-type ferredoxins are not exclusively expressed within heterocysts, as is true for cyanobacteria differentiating these cells for nitrogen fixation under aerobic growth conditions. Two open reading frames that precede fdxH have high similarity to those found at a corresponding location in Anabaena sp. strain PCC 7120. In the latter organism, they are transcribed only under nitrogen-fixing conditions, but the functions of their gene products remain unclear (D. Borthakur, M. Basche, W. J. Buikema, P. B. Borthakur, and R. Haselkorn, Mol. Gen. Genet. 221:227-234, 1990). An fdxB-type gene encoding a 2[4Fe-4S] ferredoxin not previously identified in cyanobacteria is located immediately downstream of fdxH in P. boryanum. Images PMID:8106314

  13. Brief communication: beyond the South African cave paradigm--Australopithecus africanus from Plio-Pleistocene paleosol deposits at Taung.

    PubMed

    Hopley, Philip J; Herries, Andy I R; Baker, Stephanie Edwards; Kuhn, Brian F; Menter, Colin G

    2013-06-01

    Following the discovery of the "Taung Child" (Australopithecus africanus) in 1924 in the Buxton-Norlim Limeworks near Taung, the fossil-bearing deposits associated with the Dart and Hrdlička pinnacles have been interpreted as the mined remnants of cave sediments that formed within the Plio-Pleistocene Thabaseek Tufa: either as a younger cave-fill or as contemporaneous carapace caves. When combined with the Plio-Pleistocene dolomitic cave deposits from the "Cradle of Humankind," a rather restricted view emerges that South African early hominins derived from cave deposits, whereas those of east and central Africa are derived from fluvio-lacustrine and paleosol deposits. We undertook a sedimentological and paleomagnetic analysis of the pink-colored deposit (PCS) from which the "Taung Child" is purported to have derived and demonstrate that it is a calcrete, a carbonate-rich pedogenic sediment, which formed on the paleo-land surface. The deposit extends 100 s of meters laterally beyond the Dart and Hrdlička Pinnacles where it is interbedded with the Thabaseek Tufa, indicating multiple episodes of calcrete development and tufa growth. The presence of in situ rhizoconcretions and insect trace fossils (Celliforma sp. and Coprinisphaera sp.) and the distinctive carbonate microfabric confirm that the pink deposit is a pedogenic calcrete, not a calcified cave sediment. Paleomagnetic and stratigraphic evidence indicates that a second, reversed polarity, fossil-bearing deposit (YRSS) is a younger fissure-fill formed within a solutional cavity of the normal polarity tufa and pink calcrete (PCS). These observations have implications for the dating, environment, and taphonomy of the site, and increase the likelihood of future fossil discoveries within the Buxton-Norlim Limeworks.

  14. Foraging ranges of immature African white-backed vultures (Gyps africanus) and their use of protected areas in southern Africa.

    PubMed

    Phipps, W Louis; Willis, Stephen G; Wolter, Kerri; Naidoo, Vinny

    2013-01-01

    Vultures in the Gyps genus are declining globally. Multiple threats related to human activity have caused widespread declines of vulture populations in Africa, especially outside protected areas. Addressing such threats requires the estimation of foraging ranges yet such estimates are lacking, even for widespread (but declining) species such as the African white-backed vulture (Gyps africanus). We tracked six immature African white-backed vultures in South Africa using GPS-GSM units to study their movement patterns, their use of protected areas and the time they spent in the vicinity of supplementary feeding sites. All individuals foraged widely; their combined foraging ranges extended into six countries in southern Africa (mean (± SE) minimum convex polygon area =269,103±197,187 km(2)) and three of the vultures travelled more than 900 km from the capture site. All six vultures spent the majority of their tracking periods outside protected areas. South African protected areas were very rarely visited whereas protected areas in northern Botswana and Zimbabwe were used more frequently. Two of the vultures visited supplementary feeding sites regularly, with consequent reduced ranging behaviour, suggesting that individuals could alter their foraging behaviour in response to such sites. We show that immature African white-backed vultures are capable of travelling throughout southern Africa, yet use protected areas to only a limited extent, making them susceptible to the full range of threats in the region. The standard approach of designating protected areas to conserve species is unlikely to ensure the protection of such wide-ranging species against threats in the wider landscape.

  15. Purification and properties of ferredoxinNAP, a component of naphthalene dioxygenase from Pseudomonas sp. strain NCIB 9816.

    PubMed Central

    Haigler, B E; Gibson, D T

    1990-01-01

    One of the three components of the naphthalene dioxygenase occurring in induced cells of Pseudomonas sp. strain NCIB 9816 has been purified to homogeneity. The protein contained 2 g-atoms each of iron and acid-labile sulfur and had an apparent molecular weight of 13,600. The evidence indicates that it is a ferredoxin-type protein that functions as an intermediate electron transfer protein in naphthalene dioxygenase activity. PMID:2294093

  16. Chlamydomonas reinhardtii Chloroplasts Contain a Homodimeric Pyruvate:Ferredoxin Oxidoreductase That Functions with FDX11[W][OA

    PubMed Central

    van Lis, Robert; Baffert, Carole; Couté, Yohann; Nitschke, Wolfgang; Atteia, Ariane

    2013-01-01

    Eukaryotic algae have long been known to live in anoxic environments, but interest in their anaerobic energy metabolism has only recently gained momentum, largely due to their utility in biofuel production. Chlamydomonas reinhardtii figures remarkably in this respect, because it efficiently produces hydrogen and its genome harbors many genes for anaerobic metabolic routes. Central to anaerobic energy metabolism in many unicellular eukaryotes (protists) is pyruvate:ferredoxin oxidoreductase (PFO), which decarboxylates pyruvate and forms acetyl-coenzyme A with concomitant reduction of low-potential ferredoxins or flavodoxins. Here, we report the biochemical properties of the homodimeric PFO of C. reinhardtii expressed in Escherichia coli. Electron paramagnetic resonance spectroscopy of the recombinant enzyme (Cr-rPFO) showed three distinct [4Fe-4S] iron-sulfur clusters and a thiamine pyrophosphate radical upon reduction by pyruvate. Purified Cr-rPFO exhibits a specific decarboxylase activity of 12 µmol pyruvate min−1 mg−1 protein using benzyl viologen as electron acceptor. Despite the fact that the enzyme is very oxygen sensitive, it localizes to the chloroplast. Among the six known chloroplast ferredoxins (FDX1–FDX6) in C. reinhardtii, FDX1 and FDX2 were the most efficient electron acceptors from Cr-rPFO, with comparable apparent Km values of approximately 4 µm. As revealed by immunoblotting, anaerobic conditions that lead to the induction of CrPFO did not increase levels of either FDX1 or FDX2. FDX1, being by far the most abundant ferredoxin, is thus likely the partner of PFO in C. reinhardtii. This finding postulates a direct link between CrPFO and hydrogenase and provides new opportunities to better study and engineer hydrogen production in this protist. PMID:23154536

  17. Control of reduction thermodynamics in [2Fe-2S] ferredoxins Entropy-enthalpy compensation and the influence of surface mutations.

    PubMed

    Bellei, Marzia; Battistuzzi, Gianantonio; Wu, Shu-pao; Mansy, Sheref S; Cowan, James A; Sola, Marco

    2010-06-01

    The reaction thermodynamics for the one-electron reduction of the [2Fe-2S] cluster of both human ferredoxin and various surface point mutants, in which each of the negatively charged residues Asp72, Glu73, Asp76, and Asp79 were converted to Ala, have been determined by variable temperature spectroelectrochemical measurements. The above are conserved residues that have been implicated in interactions between the vertebrate-type ferredoxins and their redox partners. In all cases, and similar to other 2Fe-ferredoxins, the reduction potentials are negative as a result of both an enthalpic and entropic stabilization of the oxidized state. Although all Hs Fd mutants, with the exception of Asp72Ala, show slightly higher E degrees ' values than that of wild type Hs Fd, according to expectations for a purely electrostatic model, they exhibit changes in the H degrees '(rc) values that are electrostatically counter-intuitive. The observation of enthalpy-entropy compensation within the protein series indicates that the mutation-induced changes in H degrees '(rc) and S degrees '(rc) are dominated by reduction-induced solvent reorganization effects. Protein-based entropic effects are likely to be responsible for the low E degrees ' value of D72A.

  18. Crystallization and preliminary X-ray studies of ferredoxin-NAD(P){sup +} reductase from Chlorobium tepidum

    SciTech Connect

    Muraki, Norifumi; Seo, Daisuke; Shiba, Tomoo; Sakurai, Takeshi; Kurisu, Genji

    2008-03-01

    Ferredoxin-NAD(P){sup +} reductase from C. tepidum has been overexpressed in E. coli, purified and crystallized. Diffraction data were collected to 2.4 Å resolution. Ferredoxin-NAD(P){sup +} reductase (FNR) is a key enzyme that catalyzes the photoreduction of NAD(P){sup +} to generate NAD(P)H during the final step of the photosynthetic electron-transport chain. FNR from the green sulfur bacterium Chlorobium tepidum is a homodimeric enzyme with a molecular weight of 90 kDa; it shares a high level of amino-acid sequence identity to thioredoxin reductase rather than to conventional plant-type FNRs. In order to understand the structural basis of the ferredoxin-dependency of this unique photosynthetic FNR, C. tepidum FNR has been heterologously expressed, purified and crystallized in two forms. Form I crystals belong to space group C222{sub 1} and contain one dimer in the asymmetric unit, while form II crystals belong to space group P4{sub 1}22 or P4{sub 3}22. Diffraction data were collected from a form I crystal to 2.4 Å resolution on the synchrotron-radiation beamline NW12 at the Photon Factory.

  19. Structural-functional characterization and physiological significance of ferredoxin-NADP reductase from Xanthomonas axonopodis pv. citri.

    PubMed

    Tondo, María Laura; Musumeci, Matías A; Delprato, María Laura; Ceccarelli, Eduardo A; Orellano, Elena G

    2011-01-01

    Xanthomonas axonopodis pv. citri is a phytopathogen bacterium that causes severe citrus canker disease. Similar to other phytopathogens, after infection by this bacterium, plants trigger a defense mechanism that produces reactive oxygen species. Ferredoxin-NADP(+) reductases (FNRs) are redox flavoenzymes that participate in several metabolic functions, including the response to reactive oxygen species. Xanthomonas axonopodis pv. citri has a gene (fpr) that encodes for a FNR (Xac-FNR) that belongs to the subclass I bacterial FNRs. The aim of this work was to search for the physiological role of this enzyme and to characterize its structural and functional properties. The functionality of Xac-FNR was tested by cross-complementation of a FNR knockout Escherichia coli strain, which exhibit high susceptibility to agents that produce an abnormal accumulation of (•)O(2)(-). Xac-FNR was able to substitute for the FNR in E. coli in its antioxidant role. The expression of fpr in X. axonopodis pv. citri was assessed using semiquantitative RT-PCR and Western blot analysis. A 2.2-fold induction was observed in the presence of the superoxide-generating agents methyl viologen and 2,3-dimethoxy-1,4-naphthoquinone. Structural and functional studies showed that Xac-FNR displayed different functional features from other subclass I bacterial FNRs. Our analyses suggest that these differences may be due to the unusual carboxy-terminal region. We propose a further classification of subclass I bacterial FNRs, which is useful to determine the nature of their ferredoxin redox partners. Using sequence analysis, we identified a ferredoxin (XAC1762) as a potential substrate of Xac-FNR. The purified ferredoxin protein displayed the typical broad UV-visible spectrum of [4Fe-4S] clusters and was able to function as substrate of Xac-FNR in the cytochrome c reductase activity. Our results suggest that Xac-FNR is involved in the oxidative stress response of Xanthomonas axonopodis pv. citri and

  20. Evidence for Lateral Transfer of Genes Encoding Ferredoxins, Nitroreductases, NADH Oxidase, and Alcohol Dehydrogenase 3 from Anaerobic Prokaryotes to Giardia lamblia and Entamoeba histolytica

    PubMed Central

    Nixon, Julie E. J.; Wang, Amy; Field, Jessica; Morrison, Hilary G.; McArthur, Andrew G.; Sogin, Mitchell L.; Loftus, Brendan J.; Samuelson, John

    2002-01-01

    Giardia lamblia and Entamoeba histolytica are amitochondriate, microaerophilic protists which use fermentation enzymes like those of bacteria to survive anaerobic conditions within the intestinal lumen. Genes encoding fermentation enzymes and related electron transport peptides (e.g., ferredoxins) in giardia organisms and amebae are hypothesized to be derived from either an ancient anaerobic eukaryote (amitochondriate fossil hypothesis), a mitochondrial endosymbiont (hydrogen hypothesis), or anaerobic bacteria (lateral transfer hypothesis). The goals here were to complete the molecular characterization of giardial and amebic fermentation enzymes and to determine the origins of the genes encoding them, when possible. A putative giardia [2Fe-2S]ferredoxin which had a hypothetical organelle-targeting sequence at its N terminus showed similarity to mitochondrial ferredoxins and the hydrogenosomal ferredoxin of Trichomonas vaginalis (another luminal protist). However, phylogenetic trees were star shaped, with weak bootstrap support, so we were unable to confirm or rule out the endosymbiotic origin of the giardia [2Fe-2S]ferredoxin gene. Putative giardial and amebic 6-kDa ferredoxins, ferredoxin-nitroreductase fusion proteins, and oxygen-insensitive nitroreductases each tentatively supported the lateral transfer hypothesis. Although there were not enough sequences to perform meaningful phylogenetic analyses, the unique common occurrence of these peptides and enzymes in giardia organisms, amebae, and the few anaerobic prokaryotes suggests the possibility of lateral transfer. In contrast, there was more robust phylogenetic evidence for the lateral transfer of G. lamblia genes encoding an NADH oxidase from a gram-positive coccus and a microbial group 3 alcohol dehydrogenase from thermoanaerobic prokaryotes. In further support of lateral transfer, the G. lamblia NADH oxidase and adh3 genes appeared to have an evolutionary history distinct from those of E. histolytica. PMID

  1. Reduction of Flavodoxin by Electron Bifurcation and Sodium Ion-dependent Reoxidation by NAD+ Catalyzed by Ferredoxin-NAD+ Reductase (Rnf).

    PubMed

    Chowdhury, Nilanjan Pal; Klomann, Katharina; Seubert, Andreas; Buckel, Wolfgang

    2016-06-03

    Electron-transferring flavoprotein (Etf) and butyryl-CoA dehydrogenase (Bcd) from Acidaminococcus fermentans catalyze the endergonic reduction of ferredoxin by NADH, which is also driven by the concomitant reduction of crotonyl-CoA by NADH, a process called electron bifurcation. Here we show that recombinant flavodoxin from A. fermentans produced in Escherichia coli can replace ferredoxin with almost equal efficiency. After complete reduction of the yellow quinone to the blue semiquinone, a second 1.4 times faster electron transfer affords the colorless hydroquinone. Mediated by a hydrogenase, protons reoxidize the fully reduced flavodoxin or ferredoxin to the semi-reduced species. In this hydrogen-generating system, both electron carriers act catalytically with apparent Km = 0.26 μm ferredoxin or 0.42 μm flavodoxin. Membrane preparations of A. fermentans contain a highly active ferredoxin/flavodoxin-NAD(+) reductase (Rnf) that catalyzes the irreversible reduction of flavodoxin by NADH to the blue semiquinone. Using flavodoxin hydroquinone or reduced ferredoxin obtained by electron bifurcation, Rnf can be measured in the forward direction, whereby one NADH is recycled, resulting in the simple equation: crotonyl-CoA + NADH + H(+) = butyryl-CoA + NAD(+) with Km = 1.4 μm ferredoxin or 2.0 μm flavodoxin. This reaction requires Na(+) (Km = 0.12 mm) or Li(+) (Km = 0.25 mm) for activity, indicating that Rnf acts as a Na(+) pump. The redox potential of the quinone/semiquinone couple of flavodoxin (Fld) is much higher than that of the semiquinone/hydroquinone couple. With free riboflavin, the opposite is the case. Based on this behavior, we refine our previous mechanism of electron bifurcation.

  2. Mapping cellular Fe-S cluster uptake and exchange reactions - divergent pathways for iron-sulfur cluster delivery to human ferredoxins.

    PubMed

    Fidai, Insiya; Wachnowsky, Christine; Cowan, J A

    2016-12-07

    Ferredoxins are protein mediators of biological electron-transfer reactions and typically contain either [2Fe-2S] or [4Fe-4S] clusters. Two ferredoxin homologues have been identified in the human genome, Fdx1 and Fdx2, that share 43% identity and 69% similarity in protein sequence and both bind [2Fe-2S] clusters. Despite the high similarity, the two ferredoxins play very specific roles in distinct physiological pathways and cannot replace each other in function. Both eukaryotic and prokaryotic ferredoxins and homologues have been reported to receive their Fe-S cluster from scaffold/delivery proteins such as IscU, Isa, glutaredoxins, and Nfu. However, the preferred and physiologically relevant pathway for receiving the [2Fe-2S] cluster by ferredoxins is subject to speculation and is not clearly identified. In this work, we report on in vitro UV-visible (UV-vis) circular dichroism studies of [2Fe-2S] cluster transfer to the ferredoxins from a variety of partners. The results reveal rapid and quantitative transfer to both ferredoxins from several donor proteins (IscU, Isa1, Grx2, and Grx3). Transfer from Isa1 to Fdx2 was also observed to be faster than that of IscU to Fdx2, suggesting that Fdx2 could receive its cluster from Isa1 instead of IscU. Several other transfer combinations were also investigated and the results suggest a complex, but kinetically detailed map for cellular cluster trafficking. This is the first step toward building a network map for all of the possible iron-sulfur cluster transfer pathways in the mitochondria and cytosol, providing insights on the most likely cellular pathways and possible redundancies in these pathways.

  3. Establishment of selected baseline blood chemistry and hematologic parameters in captive and wild-caught African white-backed vultures (Gyps africanus).

    PubMed

    Naidoo, V; Diekmann, M; Wolters, K; Swan, G E

    2008-07-01

    Despite the devastating collapse of three vulture populations on the Asian subcontinent as a result of their exposure to diclofenac, there is little available information on the normal physiology of many vulture species, including the African White-backed Vulture (Gyps africanus). Such information is needed to fully understand mechanisms for toxicity and to identify and prevent future health problems. The aim of this study was to establish baseline parameters for hematologic and selected serum chemistry parameters for this model species for further studies into the toxicity of diclofenac. Captive nonreleasable and wild African White-backed Vultures were used to determine reference values. For hematology, erythrocyte counts, hemoglobin concentration, hematocrit, packed cell volume, mean corpuscular volume, mean corpuscular hemoglobin concentration, and total and differential leukocyte counts were measured. Chemical analytes measured included sodium, potassium, calcium, albumin, and globulin concentrations, aspartate aminotransferase, creatine kinase, and alanine aminotransferase activities. Uric acid and urea concentrations and the urea:uric acid ratio also were evaluated. Values are presented as means, standard deviations, and reference intervals. The serum chemistry parameters selected may provide a starting point for the evaluation of changes in renal and hepatic function; these organ systems are most severely affected by diclofenac. Results were also compared with values reported for G. africanus nestlings, and from these results it is evident that the clinical pathologic parameters are age related. This indicates that the use of nestling values for the evaluation of clinical pathologic findings in adults may be unreliable and could lead to incorrect assumptions.

  4. Posttranslational Modifications of FERREDOXIN-NADP+ OXIDOREDUCTASE in Arabidopsis Chloroplasts1[W][OPEN

    PubMed Central

    Lehtimäki, Nina; Koskela, Minna M.; Dahlström, Käthe M.; Pakula, Eveliina; Lintala, Minna; Scholz, Martin; Hippler, Michael; Hanke, Guy T.; Rokka, Anne; Battchikova, Natalia; Salminen, Tiina A.; Mulo, Paula

    2014-01-01

    Rapid responses of chloroplast metabolism and adjustments to photosynthetic machinery are of utmost importance for plants’ survival in a fluctuating environment. These changes may be achieved through posttranslational modifications of proteins, which are known to affect the activity, interactions, and localization of proteins. Recent studies have accumulated evidence about the crucial role of a multitude of modifications, including acetylation, methylation, and glycosylation, in the regulation of chloroplast proteins. Both of the Arabidopsis (Arabidopsis thaliana) leaf-type FERREDOXIN-NADP+ OXIDOREDUCTASE (FNR) isoforms, the key enzymes linking the light reactions of photosynthesis to carbon assimilation, exist as two distinct forms with different isoelectric points. We show that both AtFNR isoforms contain multiple alternative amino termini and undergo light-responsive addition of an acetyl group to the α-amino group of the amino-terminal amino acid of proteins, which causes the change in isoelectric point. Both isoforms were also found to contain acetylation of a conserved lysine residue near the active site, while no evidence for in vivo phosphorylation or glycosylation was detected. The dynamic, multilayer regulation of AtFNR exemplifies the complex regulatory network systems controlling chloroplast proteins by a range of posttranslational modifications, which continues to emerge as a novel area within photosynthesis research. PMID:25301888

  5. Overexpression of Ferredoxin, PETF, Enhances Tolerance to Heat Stress in Chlamydomonas reinhardtii

    PubMed Central

    Lin, Yi-Hsien; Pan, Kui-You; Hung, Ching-Hui; Huang, Hsiang-En; Chen, Ching-Lian; Feng, Teng-Yung; Huang, Li-Fen

    2013-01-01

    Reactive oxygen species (ROS) produced by plants in adverse environments can cause damage to organelles and trigger cell death. Removal of excess ROS can be achieved through the ascorbate scavenger pathway to prevent plant cell death. The amount of this scavenger can be regulated by ferredoxin (FDX). Chloroplastic FDXs are electron transfer proteins that perform in distributing photosynthetic reducing power. In this study, we demonstrate that overexpression of the endogenous photosynthetic FDX gene, PETF, in Chlamydomonas reinhardtii could raise the level of reduced ascorbate and diminish H2O2 levels under normal growth conditions. Furthermore, the overexpressing PETF transgenic Chlamydomonas lines produced low levels of H2O2 and exhibited protective effects that were observed through decreased chlorophyll degradation and increased cell survival under heat-stress conditions. The findings of this study suggest that overexpression of PETF can increase the efficiency of ROS scavenging in chloroplasts to confer heat tolerance. The roles of PETF in the downregulation of the ROS level offer a method for potentially improving the tolerance of crops against heat stress. PMID:24141188

  6. Overexpression of ferredoxin, PETF, enhances tolerance to heat stress in Chlamydomonas reinhardtii.

    PubMed

    Lin, Yi-Hsien; Pan, Kui-You; Hung, Ching-Hui; Huang, Hsiang-En; Chen, Ching-Lian; Feng, Teng-Yung; Huang, Li-Fen

    2013-10-17

    Reactive oxygen species (ROS) produced by plants in adverse environments can cause damage to organelles and trigger cell death. Removal of excess ROS can be achieved through the ascorbate scavenger pathway to prevent plant cell death. The amount of this scavenger can be regulated by ferredoxin (FDX). Chloroplastic FDXs are electron transfer proteins that perform in distributing photosynthetic reducing power. In this study, we demonstrate that overexpression of the endogenous photosynthetic FDX gene, PETF, in Chlamydomonas reinhardtii could raise the level of reduced ascorbate and diminish H2O2 levels under normal growth conditions. Furthermore, the overexpressing PETF transgenic Chlamydomonas lines produced low levels of H2O2 and exhibited protective effects that were observed through decreased chlorophyll degradation and increased cell survival under heat-stress conditions. The findings of this study suggest that overexpression of PETF can increase the efficiency of ROS scavenging in chloroplasts to confer heat tolerance. The roles of PETF in the downregulation of the ROS level offer a method for potentially improving the tolerance of crops against heat stress.

  7. Protein motifs involved in coenzyme interaction and enzymatic efficiency in anabaena ferredoxin-NADP+ reductase.

    PubMed

    Peregrina, José R; Herguedas, Beatriz; Hermoso, Juan A; Martínez-Júlvez, Marta; Medina, Milagros

    2009-04-14

    Ferredoxin-NADP+ reductases (FNRs) must determine the coenzyme specificity and allow the transient encounter between N5 of its flavin cofactor and C4 of the coenzyme nicotinamide for efficient hydride transfer. Combined site-directed replacements in different putative determinants of the FNR coenzyme specificity were simultaneously produced. The resulting variants were structurally and functionally analyzed for their binding and hydride transfer abilities to the FNR physiological coenzyme NADP+/H, as well as to NAD+/H. The previously studied Y303S mutation is the only one that significantly enhances specificity for NAD+. Combination of mutations from the pyrophosphate or 2'-phosphate regions, even including Y303S, does not improve activity with NAD+, despite structures of these FNRs show how particular coenzyme-binding regions resembled motifs found in NAD+/H-dependent enzymes of the FNR family. Therefore, the "rational approach" did not succeed well, and coenzyme specificity redesign in the FNR family will be more complex than that anticipated in other NADP+/NAD+ families.

  8. Subcellular localization of ferredoxin-NADP(+) oxidoreductase in phycobilisome retaining oxygenic photosysnthetic organisms.

    PubMed

    Morsy, Fatthy Mohamed; Nakajima, Masato; Yoshida, Takayuki; Fujiwara, Tatsuki; Sakamoto, Toshio; Wada, Keishiro

    2008-01-01

    Ferredoxin-NADP(+) oxidoreductase (FNR) catalyzing the terminal step of the linear photosynthetic electron transport was purified from the cyanobacterium Spirulina platensis and the red alga Cyanidium caldarium. FNR of Spirulina consisted of three domains (CpcD-like domain, FAD-binding domain, and NADP(+)-binding domain) with a molecular mass of 46 kDa and was localized in either phycobilisomes or thylakoid membranes. The membrane-bound FNR with 46 kDa was solublized by NaCl and the solublized FNR had an apparent molecular mass of 90 kDa. FNR of Cyanidium consisted of two domains (FAD-binding domain and NADP(+)-binding domain) with a molecular mass of 33 kDa. In Cyanidium, FNR was found on thylakoid membranes, but there was no FNR on phycobilisomes. The membrane-bound FNR of Cyanidium was not solublized by NaCl, suggesting the enzyme is tightly bound in the membrane. Although both cyanobacteria and red algae are photoautotrophic organisms bearing phycobilisomes as light harvesting complexes, FNR localization and membrane-binding characteristics were different. These results suggest that FNR binding to phycobilisomes is not characteristic for all phycobilisome retaining oxygenic photosynthetic organisms, and that the rhodoplast of red algae had possibly originated from a cyanobacterium ancestor, whose FNR lacked the CpcD-like domain.

  9. A de novo designed 2[4Fe-4S] ferredoxin mimic mediates electron transfer.

    PubMed

    Roy, Anindya; Sommer, Dayn Joseph; Schmitz, Robert Arthur; Brown, Chelsea Lynn; Gust, Devens; Astashkin, Andrei; Ghirlanda, Giovanna

    2014-12-10

    [Fe-S] clusters, nature's modular electron transfer units, are often arranged in chains that support long-range electron transfer. Despite considerable interest, the design of biomimetic artificial systems emulating multicluster-binding proteins, with the final goal of integrating them in man-made oxidoreductases, remains elusive. Here, we report a novel bis-[4Fe-4S] cluster binding protein, DSD-Fdm, in which the two clusters are positioned within a distance of 12 Å, compatible with the electronic coupling necessary for efficient electron transfer. The design exploits the structural repeat of coiled coils as well as the symmetry of the starting scaffold, a homodimeric helical protein (DSD). In total, eight hydrophobic residues in the core of DSD were replaced by eight cysteine residues that serve as ligands to the [4Fe-4S] clusters. Incorporation of two [4Fe-4S] clusters proceeds with high yield. The two [4Fe-4S] clusters are located in the hydrophobic core of the helical bundle as characterized by various biophysical techniques. The secondary structure of the apo and holo proteins is conserved; further, the incorporation of clusters results in stabilization of the protein with respect to chemical denaturation. Most importantly, this de novo designed protein can mimic the function of natural ferredoxins: we show here that reduced DSD-Fdm transfers electrons to cytochrome c, thus generating the reduced cyt c stoichiometrically.

  10. Influence of 120 kDa Pyruvate:Ferredoxin Oxidoreductase on Pathogenicity of Trichomonas vaginalis.

    PubMed

    Song, Hyun-Ouk

    2016-02-01

    Trichomonas vaginalis is a flagellate protozoan parasite and commonly infected the lower genital tract in women and men. Iron is a known nutrient for growth of various pathogens, and also reported to be involved in establishment of trichomoniasis. However, the exact mechanism was not clarified. In this study, the author investigated whether the 120 kDa protein of T. vaginalis may be involved in pathogenicity of trichomonads. Antibodies against 120 kDa protein of T. vaginalis, which was identified as pyruvate:ferredoxin oxidoreductase (PFOR) by peptide analysis of MALDI-TOF-MS, were prepared in rabbits. Pretreatment of T. vaginalis with anti-120 kDa Ab decreased the proliferation and adherence to vaginal epithelial cells (MS74) of T. vaginalis. Subcutaneous tissue abscess in anti-120 kDa Ab-treated T. vaginalis-injected mice was smaller in size than that of untreated T. vaginalis-infected mice. Collectively, the 120 kDa protein expressed by iron may be involved in proliferation, adhesion to host cells, and abscess formation, thereby may influence on the pathogenicity of T. vaginalis.

  11. Ferredoxin Competes with Bacterial Frataxin in Binding to the Desulfurase IscS*

    PubMed Central

    Yan, Robert; Konarev, Petr V.; Iannuzzi, Clara; Adinolfi, Salvatore; Roche, Béatrice; Kelly, Geoff; Simon, Léa; Martin, Stephen R.; Py, Béatrice; Barras, Frédéric; Svergun, Dmitri I.; Pastore, Annalisa

    2013-01-01

    The bacterial iron-sulfur cluster (isc) operon is an essential machine that is highly conserved from bacteria to primates and responsible for iron-sulfur cluster biogenesis. Among its components are the genes for the desulfurase IscS that provides sulfur for cluster formation, and a specialized ferredoxin (Fdx) whose role is still unknown. Preliminary evidence suggests that IscS and Fdx interact but nothing is known about the binding site and the role of the interaction. Here, we have characterized the interaction using a combination of biophysical tools and mutagenesis. By modeling the Fdx·IscS complex based on experimental restraints we show that Fdx competes for the binding site of CyaY, the bacterial ortholog of frataxin and sits in a cavity close to the enzyme active site. By in vivo mutagenesis in bacteria we prove the importance of the surface of interaction for cluster formation. Our data provide the first structural insights into the role of Fdx in cluster assembly. PMID:23839945

  12. Structural and mutational studies of an electron transfer complex of maize sulfite reductase and ferredoxin.

    PubMed

    Kim, Ju Yaen; Nakayama, Masato; Toyota, Hiroshi; Kurisu, Genji; Hase, Toshiharu

    2016-08-01

    The structure of the complex of maize sulfite reductase (SiR) and ferredoxin (Fd) has been determined by X-ray crystallography. Co-crystals of the two proteins prepared under different conditions were subjected to the diffraction analysis and three possible structures of the complex were solved. Although topological relationship of SiR and Fd varied in each of the structures, two characteristics common to all structures were found in the pattern of protein-protein interactions and positional arrangements of redox centres; (i) a few negative residues of Fd contact with a narrow area of SiR with positive electrostatic surface potential and (ii) [2Fe-2S] cluster of Fd and [4Fe-4S] cluster of SiR are in a close proximity with the shortest distance around 12 Å. Mutational analysis of a total of seven basic residues of SiR distributed widely at the interface of the complex showed their importance for supporting an efficient Fd-dependent activity and a strong physical binding to Fd. These combined results suggest that the productive electron transfer complex of SiR and Fd could be formed through multiple processes of the electrostatic intermolecular interaction and this implication is discussed in terms of the multi-functionality of Fd in various redox metabolisms.

  13. Expression analysis of the fpr (ferredoxin-NADP{sup +} reductase) gene in Pseudomonas putida KT2440

    SciTech Connect

    Lee, Yunho; Pena-Llopis, Samuel; Kang, Yoon-Suk; Shin, Hyeon-Dong; Demple, Bruce; Madsen, Eugene L.; Jeon, Che Ok; Park, Woojun . E-mail: wpark@korea.ac.kr

    2006-01-27

    The ferredoxin-NADP{sup +} reductase (fpr) participates in cellular defense against oxidative damage. The fpr expression in Pseudomonas putida KT2440 is induced by oxidative and osmotic stresses. FinR, a LysR-type transcriptional factor near the fpr gene in the P. putida KT2440 genome, is required for induction of the fpr under both conditions. We have shown that the fpr and finR gene products can counteract the effects of oxidative and osmotic stresses. Interestingly, FinR-independent expression occurs either during a long period of incubation with paraquat or with high concentrations of oxidative stress agent. This result indicates that there may be additional regulators present in the P. putida KT2440 genome. In contrast to in vivo expression kinetics of fpr from the plant pathogen, Pseudomonas syringae, the fpr gene from P. putida KT2440 exhibited unusually prolonged expression after oxidative stress. Transcriptional fusion and Northern blot analysis studies indicated that the FinR is negatively autoregulated. Expression of the fpr promoter was higher in minimal media than in rich media during exponential phase growth. Consistent with this result, the fpr and finR mutants had a long lag phase in minimal media in contrast to wild-type growth characteristics. Antioxidants such as ascorbate could increase the growth rate of all tested strains in minimal media. This result confirmed that P. putida KT2440 experienced more oxidative stress during exponential growth in minimal media than in rich media. Endogenous promoter activity of the fpr gene is much higher during exponential growth than during stationary growth. These findings demonstrate new relationships between fpr, finR, and the physiology of oxidative stress in P. putida KT2440.

  14. A New Type of YumC-Like Ferredoxin (Flavodoxin) Reductase Is Involved in Ribonucleotide Reduction

    PubMed Central

    Shen, Jing; Jensen, Peter Ruhdal

    2015-01-01

    ABSTRACT The trxB2 gene, which is annotated as a thioredoxin reductase, was found to be essential for growth of Lactococcus lactis in the presence of oxygen. The corresponding protein (TrxB2) showed a high similarity with Bacillus subtilis YumC (E value = 4.0E−88), and YumC was able to fully complement the ΔtrxB2 mutant phenotype. YumC represents a novel type of ferredoxin (flavodoxin) reductase (FdR) with hitherto-unknown biological function. We adaptively evolved the ΔtrxB2 mutant under aerobic conditions to find suppressor mutations that could help elucidate the involvement of TrxB2 in aerobic growth. Genome sequencing of two independent isolates, which were able to grow as well as the wild-type strain under aerated conditions, revealed the importance of mutations in nrdI, encoding a flavodoxin involved in aerobic ribonucleotide reduction. We suggest a role for TrxB2 in nucleotide metabolism, where the flavodoxin (NrdI) serves as its redox partner, and we support this hypothesis by showing the beneficial effect of deoxynucleosides on aerobic growth of the ΔtrxB2 mutant. Finally, we demonstrate, by heterologous expression, that the TrxB2 protein functionally can substitute for YumC in B. subtilis but that the addition of deoxynucleosides cannot compensate for the lethal phenotype displayed by the B. subtilis yumC knockout mutant. PMID:26507228

  15. Circular dichroism and magnetic circular dichroism of Azotobacter vinelandii ferredoxin I.

    PubMed

    Stephens, P J; Jensen, G M; Devlin, F J; Morgan, T V; Stout, C D; Martin, A E; Burgess, B K

    1991-04-02

    Room temperature circular dichroism (CD) and low temperature magnetic circular dichroism (MCD) spectra of air-oxidized and dithionite-reduced Azotobacter vinelandii ferredoxin I (FdI), a [( 4Fe-4S]2+/1+, [3Fe-4S]1+/0) protein, are reported. Unlike the CD of oxidized FdI, the CD of dithionite-reduced FdI exhibits significant pH dependence, consistent with protonation-deprotonation at or near the cluster reduced: the [3Fe-4S] cluster. The MCD of reduced FdI, which originates in the paramagnetic reduced [3Fe-4S]0 cluster, is also pH-dependent. Detailed studies of the field dependence and temperature dependence of the MCD of oxidized and reduced FdI, in the latter case at pH 6.0 and 8.3, are reported. The low-field temperature dependence of the MCD of oxidized FdI, which originates in the paramagnetic oxidized [3Fe-4S]1+ cluster, establishes the absence of a significant population of excited electronic states of this cluster up to 60 K. The low-field temperature dependence of the MCD of reduced FdI establishes that the ground-state manifold of the reduced [3Fe-4S]0 cluster possesses S greater than or equal to 2 at both pH 6.0 and 8.3. Analysis, assuming S = 2 and an axial zero-field splitting Hamiltonian, leads to D = -2.0 and -3.5 cm-1 at pH 6.0 and 8.3, respectively. The site of the (de)protonation affecting the spectroscopic properties of the [3Fe-4S] cluster remains unknown.

  16. Formation of the Fe-S cluster of ferredoxin in lysed spinach chloroplasts. [Spinacia oleracea

    SciTech Connect

    Takahashi, Yasuhiro; Mitsui, Akira; Matsubara, Hiroshi )

    1991-01-01

    In vitro formation of the {sup 35}S-labeled Fe-S cluster of ferredoxin (Fd) has been achieved by incubating apo-Fd and ({sup 35}S)cysteine with osmotically lysed chloroplasts of spinach (Spinacia oleracea). Correct integration of the {sup 35}S-labeled Fe-S cluster into Fd was verified on the basis of the following: (a) Under nondenaturing conditions, {sup 35}S-labeled holo-Fd showed the same electrophoretic mobility as authentic holo-Fd; (b) {sup 35}S-labeled holo-Fd showed an ability to bind Fd-NADP{sup +} reductase; (c) the {sup 35}S-labeled moiety was removed from the Fd polypeptide by TCA treatment but not by 2-mercaptoethanol treatment; (d) externally added pea II apo-Fd was converted to {sup 35}S-labeled holo-Fd. This reconstitution was dependent on both ATP and light, and formation of the {sup 35}S-labeled Fe-S cluster was observed upon addition of ATP or when an ATP generation-system was constructed in the light. In contrast, ATP-consuming systems abolished the Fe-S cluster formation. A non-hydrolyzable ATP analog was unable to serve as an ATP substitute, indicating the requirement of ATP hydrolysis for cluster formation. GTP was able to substitute for ATP, but CTP and UTP were less effective. Fe-S cluster formation in lysed chloroplasts was stimulated by light even in the presence of added ATP. Light stimulation was inhibited by DCMU or methyl viologen but not by NH{sub 4}{sup +}. NADPH was able to substitute for light, indicating that light energy is required for the production of reducing compounds such as NADPH in addition to the generation of ATP.

  17. Position des lignes temporales sur le cranium de «Mrs » Ples (A.africanus) : une attribution sexuelle est-elle possible ?Possible position of the temporal lines on the cranium of 'Mrs' Ples (A. africanus): is sexual determination possible?

    NASA Astrophysics Data System (ADS)

    Prat, Sandrine; Thackeray, John Francis

    2001-03-01

    The cranium and associated matrix of Sts 5, a cranium of Australopithecus africanus is re-examined in the context of an unfused sagittal suture and the position of the temporal lines. These lines are not developed as a sagittal crest although they are close to the mid-sagittal line. A comparative study of the presence of sagittal crests in male, female, juvenile and adult specimens of extant great apes ( Gorilla, Pan, Pongo) suggests that the existence of a sagittal crest is influenced to a greater extent by anatomical age rather than by the sex of the individuals.

  18. Crystal structure of the FAD-containing ferredoxin-NADP+ reductase from the plant pathogen Xanthomonas axonopodis pv. citri.

    PubMed

    Tondo, María Laura; Hurtado-Guerrero, Ramon; Ceccarelli, Eduardo A; Medina, Milagros; Orellano, Elena G; Martínez-Júlvez, Marta

    2013-01-01

    We have solved the structure of ferredoxin-NADP(H) reductase, FPR, from the plant pathogen Xanthomonas axonopodis pv. citri, responsible for citrus canker, at a resolution of 1.5 Å. This structure reveals differences in the mobility of specific loops when compared to other FPRs, probably unrelated to the hydride transfer process, which contributes to explaining the structural and functional divergence between the subclass I FPRs. Interactions of the C-terminus of the enzyme with the phosphoadenosine of the cofactor FAD limit its mobility, thus affecting the entrance of nicotinamide into the active site. This structure opens the possibility of rationally designing drugs against the X. axonopodis pv. citri phytopathogen.

  19. cDNA cloning, expression levels and gene mapping of photosynthetic and non-photosynthetic ferredoxin genes in sunflower (Helianthus annuus L.).

    PubMed

    Venegas-Calerón, M; Zambelli, A; Ruiz-López, N; Youssar, L; León, A; Garcés, R; Martínez-Force, Enrique

    2009-03-01

    Fatty acid desaturation in plastids and chloroplasts depends on the electron-donor activity of ferredoxins. Using degenerate oligonucleotides designed from known photosynthetic and heterotrophic plant ferredoxin sequences, two full-length ferredoxin cDNAs were cloned from sunflower (Helianthus annuus L.) leaves and developing seeds, HaFd1 and HaFd2, homologous to photosynthetic and non-photosynthetic ferredoxins, respectively. Based on these cDNAs, the respective genomic sequences were obtained and the presence of DNA polymorphisms was investigated. Complete sequencing of the HaFd1 and HaFd2 genes in different lines indicated the presence of two haplotypes for HaFd2 and their alignment showed that sequence polymorphisms are restricted to the 5'-NTR intron. In addition, specific DNA markers for the HaFd1 and HaFd2 genes were developed that enabled the genes to be mapped. Accordingly, the HaFd1 locus maps to linkage group 10 of the public sunflower map, while the HaFd2 locus maps to linkage group 11. Both ferredoxins display different spatial-temporal patterns of expression. While HaFd2 is expressed at similar levels in all tissues tested (leaves, stem, roots, cotyledons and developing seeds), HaFd1 is more strongly expressed in green tissues than in all the other tissues tested. Both photosynthetic- and heterotrophic-ferredoxins are present in sunflower seeds and may contribute to fatty acid desaturation during oil accumulation. Nevertheless, the levels of HaFd2 expression during seed formation are distinct in lines that only varied in the HaFd2 haplotypes they expressed.

  20. The Bidirectional NiFe-hydrogenase in Synechocystis sp. PCC 6803 Is Reduced by Flavodoxin and Ferredoxin and Is Essential under Mixotrophic, Nitrate-limiting Conditions*

    PubMed Central

    Gutekunst, Kirstin; Chen, Xi; Schreiber, Karoline; Kaspar, Ursula; Makam, Srinivas; Appel, Jens

    2014-01-01

    Cyanobacteria are able to use solar energy for the production of hydrogen. It is generally accepted that cyanobacterial NiFe-hydrogenases are reduced by NAD(P)H. This is in conflict with thermodynamic considerations, as the midpoint potentials of NAD(P)H do not suffice to support the measured hydrogen production under physiological conditions. We show that flavodoxin and ferredoxin directly reduce the bidirectional NiFe-hydrogenase of Synechocystis sp. PCC 6803 in vitro. A merodiploid ferredoxin-NADP reductase mutant produced correspondingly more photohydrogen. We furthermore found that the hydrogenase receives its electrons via pyruvate:flavodoxin/ferredoxin oxidoreductase (PFOR)-flavodoxin/ferredoxin under fermentative conditions, enabling the cells to gain ATP. These results strongly support that the bidirectional NiFe-hydrogenases in cyanobacteria function as electron sinks for low potential electrons from photosystem I and as a redox balancing device under fermentative conditions. However, the selective advantage of this enzyme is not known. No strong phenotype of mutants lacking the hydrogenase has been found. Because bidirectional hydrogenases are widespread in aquatic nutrient-rich environments that are capable of triggering phytoplankton blooms, we mimicked those conditions by growing cells in the presence of increased amounts of dissolved organic carbon and dissolved organic nitrogen. Under these conditions the hydrogenase was found to be essential. As these conditions close the two most important sinks for reduced flavodoxin/ferredoxin (CO2-fixation and nitrate reduction), this discovery further substantiates the connection between flavodoxin/ferredoxin and the NiFe-hydrogenase. PMID:24311779

  1. The ferredoxin-like domain of the activating enzyme is required for generating a lasting glycyl radical in 4-hydroxyphenylacetate decarboxylase.

    PubMed

    Selvaraj, Brinda; Pierik, Antonio J; Bill, Eckhard; Martins, Berta M

    2014-12-01

    4-Hydroxyphenylacetate decarboxylase-activating enzyme (4Hpad-AE) uses S-adenosylmethionine (SAM or AdoMet) and a [4Fe-4S] ²⁺/⁺cluster (RS cluster) to generate a stable glycyl radical on the decarboxylase. 4Hpad-AE might bind up to two auxiliary [4Fe-4S] clusters coordinated by a ferredoxin-like insert C-terminal to the RS cluster-binding motif. Except for the AEs of pyruvate formate-lyase and anaerobic ribonucleotide reductase, all glycyl radical-activating enzymes possess a similar ferredoxin-like domain, whose functional role is still poorly understood. To assess the role of the putative ferredoxin clusters from 4Hpad-AE, we combined biochemical and spectroscopic methods to characterize a truncated version of the protein (Δ66-AE) devoid of the ferredoxin-like domain. We found that Δ66-AE is stable, harbors a fully active RS cluster and can activate the decarboxylase. From the similar cleavage rates for S-adenosylmethionine of Δ66-AE and wild-type AE, we infer the reactivity of the RS cluster is unperturbed by the absence of the ferredoxin-like domain. Thus, the auxiliary clusters are not required as electron conduit to the RS cluster for effective reductive cleavage of SAM. The activation of the decarboxylase by Δ66-AE is almost as fast as with wild-type AE, but the generated glycyl radical is short living. We postulate that the ferredoxin-like domain is not required for SAM-dependent glycyl radical generation in the decarboxylase, but is necessary for producing a lasting glycyl radical.

  2. Browsing gene banks for Fe2S2 ferredoxins and structural modeling of 88 plant-type sequences: an analysis of fold and function.

    PubMed

    Bertini, Ivano; Luchinat, Claudio; Provenzani, Alessandro; Rosato, Antonio; Vasos, Paul R

    2002-01-01

    One-hundred-and-seventy-nine sequences of Fe2S2 ferredoxins and ferredoxin precursors were identified in and retrieved from currently available protein and cDNA databases. On the basis of their cluster-binding patterns, these sequences were divided into three groups: those containing the CX4CX2CXnC pattern (plant-type ferredoxins), those with the CX5CX2CXnC pattern (adrenodoxins), and those with a different pattern. These three groups contain, respectively, 139, 36, and 4 sequences. After excluding ferredoxin precursors in the first group, two subgroups were identified, again based on their cluster-binding patterns: 88 sequences had the CX4CX2CX29C pattern, and 29 had the CX4CX2CXmC (m not equal 29) pattern. The structures of the 88 ferredoxins with the CX4CX2CX29C pattern were modeled based on the available experimental structures of nine proteins within this same group. The modeling procedure was tested by building structural models for the ferredoxins with known structures. The models resulted, on average, in being within 1 A of the backbone root-mean-square deviation from the corresponding experimental structures. In addition, these structural models were shown to be of high quality by using assessment procedures based on energetic and stereochemical parameters. Thus, these models formed a reliable structural database for this group of ferredoxins, which is meaningful within the framework of current structural genomics efforts. From the analysis of the structural database generated it was observed that the secondary structural elements and the overall three-dimensional structures are maintained throughout the superfamily. In particular, the residues in the hydrophobic core of the protein were found to be either absolutely conserved or conservatively substituted. In addition, certain solvent-accessible charged groups, as well as hydrophobic groups, were found to be conserved to the same degree as the core residues. The patterns of conservation of exposed

  3. The function and properties of the iron-sulfur center in spinach ferredoxin: Thioredoxin reductase: A new biological role for iron-sulfur clusters

    SciTech Connect

    Staples, C.R.; Ameyibor, E.; Fu, Weiguang; Johnson, M.K.

    1996-09-03

    Thioredoxin reduction in chloroplasts in catalyzed by a unique class of disulfide reductases which use a [2Fe-2S]{sup 2+/+} ferredoxin as the electron donor and contain an Fe-S cluster as the sole prosthetic group in addition to the active-site disulfide. The nature, properties, and function of the Fe-S cluster in spinach ferredoxin: thioredoxin reductase (FTR) have been investigated by the combination of UV/visible absorption, variable-temperature magnetic circular dichroism (MCD), EPR, and resonance Raman (RR) spectroscopies. 66 refs., 5 figs., 1 tab.

  4. In vitro antifungal susceptibility of the yeast- and mould-phases of the dimorphic fungal pathogen, Emergomyces africanus (formerly Emmonsia species), from HIV-infected South African patients.

    PubMed

    Maphanga, Tsidiso G; Britz, Erika; Zulu, Thokozile G; Mpembe, Ruth S; Naicker, Serisha D; Schwartz, Ilan S; Govender, Nelesh P

    2017-03-29

    Introduction: Disseminated emmonsiosis is an important AIDS-related mycosis in South Africa caused by Emergomyces africanus, a newly-described and -renamed dimorphic fungal pathogen. In vitro antifungal susceptibility data can guide management.Materials and Methods: Identification of invasive clinical isolates was confirmed phenotypically and by sequencing the internal transcribed spacer region. Yeast and mould-phase MICs for fluconazole, voriconazole, itraconazole, posaconazole, caspofungin, anidulafungin, micafungin and flucytosine were determined using custom-made frozen broth microdilution (BMD) panels, as per Clinical and Laboratory Standards Institute recommendations. MICs for amphotericin B, itraconazole, posaconazole and voriconazole were determined by Etest.Results: Fifty unique Emergomyces africanus isolates were tested. Yeast- and mould-phase geometric mean (GM) BMD and Etest MICs values were 0.01 mg/L for itraconazole. Voriconazole and posaconazole GM BMD MICs were 0.01 mg/L for both phases, while GM Etest MICs were 0.001 mg/L and 0.002 mg/L, respectively. Fluconazole GM BMD MICs were 0.18 mg/L for both phases. For amphotericin B, GM Etest MICs for the yeast- and mould-phases were 0.03 mg/L and 0.01 mg/L. The echinocandins and flucytosine had very limited in vitro activity. Treatment and outcome data were available for 37 patients; in a multivariable model including MIC data, only isolation from blood (OR 8.6, 95% CI 1.3 - 54.4, p = 0.02) or bone marrow (OR 12.1, 95% CI 1.2 - 120.2, p = 0.03) (vs. skin biopsy) was associated with death.Conclusions:In vitro susceptibility data support management of disseminated emmonsiosis with amphotericin B followed by itraconazole, voriconazole or posaconazole. Fluconazole was a relatively less potent agent.

  5. Redox-dependent conformational selection in a Cys4Fe2S2 ferredoxin.

    PubMed

    Pochapsky, T C; Kostic, M; Jain, N; Pejchal, R

    2001-05-15

    Putidaredoxin (Pdx), a Cys4Fe2S2 ferredoxin from Pseudomonas putida, exhibits redox-dependent binding to its physiological redox partner, cytochrome P450(cam) (CYP101), with the reduced form of Pdx (Pdx(r)) binding with greater affinity to oxidized camphor-bound CYP101 than the oxidized form, Pdx(o). It has been previously shown that Pdx(o) is more dynamic than Pdx(r) on all accessible time scales, and it has been proposed that Pdx(r) samples only a fraction of the conformational substates populated by Pdx(o) on a time average. It is postulated that the ensemble subset populated by Pdx(r) is the same subset that binds CYP101, providing a mechanism for coupling the Pdx oxidation state to binding affinity for CYP101. Evidence from a variety of sources, including redox-dependent shifts of 15N and 13C resonances, indicates that the metal cluster binding loop of Pdx is the primary determinant of redox-dependent conformational selection. Patterns of paramagnetic effects suggest that the metal cluster binding loop contracts around the metal cluster upon reduction, possibly due to the strengthening of hydrogen bonds between the sulfur atoms of the metal cluster and the surrounding polypeptide NH and OH groups. Effects of this perturbation are then transmitted mechanically to other affected regions of the protein. A specific mutation has been introduced into the metal binding loop of Pdx, G40N, that slows conformational exchange sufficiently that the ensemble of conformational substates in Pdx(o) are directly observable as severe broadenings or splittings in affected NMR resonances. Many of the residues most affected by the mutation also show significant exchange contributions to 15N T(2) relaxation in wild-type Pdx(o). As predicted, G40N Pdx(r) shows a collapse of many of these multiplets and broadened lines to form much sharper resonances that are essentially identical to those observed in wild-type Pdx(r), indicating that Pdx(r) occupies fewer conformational substates

  6. Primary structures of the precursor and mature forms of stearoyl-acyl carrier protein desaturase from safflower embryos and requirement of ferredoxin for enzyme activity.

    PubMed Central

    Thompson, G A; Scherer, D E; Foxall-Van Aken, S; Kenny, J W; Young, H L; Shintani, D K; Kridl, J C; Knauf, V C

    1991-01-01

    Stearoyl-acyl carrier protein (ACP) desaturase (EC 1.14.99.6) catalyzes the principal conversion of saturated fatty acids to unsaturated fatty acids in the synthesis of vegetable oils. Stearoyl-ACP desaturase was purified from developing embryos of safflower seed, and extensive amino acid sequence was determined. The amino acid sequence was used in conjunction with polymerase chain reactions to clone a full-length cDNA. The primary structure of the protein, as deduced from the nucleotide sequence of the cDNA, includes a 33-amino-acid transit peptide not found in the purified enzyme. Expression in Escherichia coli of a gene encoding the mature form of stearoyl-ACP desaturase did not result in an altered fatty acid composition. However, active enzyme was detected when assayed in vitro with added spinach ferredoxin. The lack of significant activity in vitro without added ferredoxin and the lack of observed change in fatty acid composition indicate that ferredoxin is a required cofactor for the enzyme and that E. coli ferredoxin functions poorly, if at all, as an electron donor for the plant enzyme. Images PMID:2006194

  7. Identification and cloning of two immunogenic C. perfringens proteins, elongation factor Tu (EF-Tu) and pyruvate:ferredoxin oxidoreductase (PFO) of Clostridium perfringens

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Clostridium related poultry diseases such as necrotic enteritis (NE) and gangrenous dermatitis (GD) cause substantial economic losses on a global scale. Two antigenic C. perfringens proteins, elongation factor Tu (EF-Tu) and pyruvate:ferredoxin oxidoreductase (PFO), were identified by reaction with...

  8. Enhanced heterologous expression of two Streptomyces griseolus cytochrome P450s and Streptomyces coelicolor ferredoxin reductase as potentially efficient hydroxylation catalysts.

    PubMed

    Hussain, Haitham A; Ward, John M

    2003-01-01

    The herbicide-inducible, soluble cytochrome P450s CYP105A1 and CYP105B1 and their adjacent ferredoxins, Fd1 and Fd2, of Streptomyces griseolus were expressed in Escherichia coli to high levels. Conditions for high-level expression of active enzyme able to catalyze hydroxylation have been developed. Analysis of the expression levels of the P450 proteins in several different E. coli expression hosts identified E. coli BL21 Star(DE3)pLysS as the optimal host cell to express CYP105B1 as judged by CO difference spectra. Examination of the codons used in the CYP1051A1 sequence indicated that it contains a number of codons corresponding to rare E. coli tRNA species. The level of its expression was improved in the modified forms of E. coli BL21(DE3), which contain extra copies of rare codon E. coli tRNA genes. The activity of correctly folded cytochrome P450s was further enhanced by cloning a ferredoxin reductase from Streptomyces coelicolor downstream of CYP105A1 and CYP105B1 and their adjacent ferredoxins. Expression of CYP105A1 and CYP105B1 was also achieved in Streptomyces lividans 1326 by cloning the P450 genes and their ferredoxins into the expression vector pBW160. S. lividans 1326 cells containing CYP105A1 or CYP105B1 were able efficiently to dealkylate 7-ethoxycoumarin.

  9. Influence of pH and ionic strength on electrostatic properties of ferredoxin, FNR, and hydrogenase and the rate constants of their interaction

    NASA Astrophysics Data System (ADS)

    Diakonova, A. N.; Khrushchev, S. S.; Kovalenko, I. B.; Riznichenko, G. Yu; Rubin, A. B.

    2016-10-01

    Ferredoxin (Fd) protein transfers electrons from photosystem I (PSI) to ferredoxin:NADP+-reductase (FNR) in the photosynthetic electron transport chain, as well as other metabolic pathways. In some photosynthetic organisms including cyanobacteria and green unicellular algae under anaerobic conditions Fd transfers electrons not only to FNR but also to hydrogenase—an enzyme which catalyzes reduction of atomic hydrogen to H2. One of the questions posed by this competitive relationship between proteins is which characteristics of thylakoid stroma media allow switching of the electron flow between the linear path PSI-Fd-FNR-NADP+ and the path PSI-Fd-hydrogenase-H2. The study was conducted using direct multiparticle simulation approach. In this method protein molecules are considered as individual objects that experience Brownian motion and electrostatic interaction with the surrounding media and each other. Using the model we studied the effects of pH and ionic strength (I) upon complex formation between ferredoxin and FNR and ferredoxin and hydrogenase. We showed that the rate constant of Fd-FNR complex formation is constant in a wide range of physiologically significant pH values. Therefore it can be argued that regulation of FNR activity doesn’t involve pH changes in stroma. On the other hand, in the model rate constant of Fd-hydrogenase interaction dramatically depends upon pH: in the range 7-9 it increases threefold. It may seem that because hydrogenase reduces protons it should be more active when pH is acidic. Apparently, regulation of hydrogenase’s affinity to both her reaction partners (H+ and Fd) is carried out by changes in its electrostatic properties. In the dark, the protein is inactive and in the light it is activated and starts to interact with both Fd and H+. Therefore, we can conclude that in chloroplasts the rate of hydrogen production is regulated by pH through the changes in the affinity between hydrogenase and ferredoxin.

  10. Spectroscopic and functional properties of novel 2[4Fe-4S] cluster-containing ferredoxins from the green sulfur bacterium Chlorobium tepidum.

    PubMed

    Yoon, K S; Bobst, C; Hemann, C F; Hille, R; Tabita, F R

    2001-11-23

    Two distinct ferredoxins, Fd I and Fd II, were isolated and purified to homogeneity from photoautotrophically grown Chlorobium tepidum, a moderately thermophilic green sulfur bacterium that assimilates carbon dioxide by the reductive tricarboxylic acid cycle. Both ferredoxins serve a crucial role as electron donors for reductive carboxylation, catalyzed by a key enzyme of this pathway, pyruvate synthase/pyruvate ferredoxin oxidoreductase. The reduction potentials of Fd I and Fd II were determined by cyclic voltammetry to be -514 and -584 mV, respectively, which are more electronegative than any previously studied Fds in which two [4Fe-4S] clusters display a single transition. Further spectroscopic studies indicated that the CD spectrum of oxidized Fd I closely resembled that of Fd II; however, both spectra appeared to be unique relative to ferredoxins studied previously. Double integration of the EPR signal of the two Fds yielded approximately approximately 2.0 spins per molecule, compatible with the idea that C. tepidum Fd I and Fd II accept 2 electrons upon reduction. These results suggest that the C. tepidum Fd I and Fd II polypeptides each contain two bound [4Fe-4S] clusters. C. tepidum Fd I and Fd II are novel 2[4Fe-4S] Fds, which were shown previously to function as biological electron donors or acceptors for C. tepidum pyruvate synthase/pyruvate ferredoxin oxidoreductase (Yoon, K.-S., Hille, R., Hemann, C. F., and Tabita, F. R. (1999) J. Biol. Chem. 274, 29772-29778). Kinetic measurements indicated that Fd I had approximately 2.3-fold higher affinity than Fd II. The results of amino acid sequence alignments, molecular modeling, oxidation-reduction potentials, and spectral properties strongly indicate that the C. tepidum Fds are chimeras of both clostridial-type and chromatium-type Fds, suggesting that the two Fds are likely intermediates in the evolutional development of 2[4Fe-4S] clusters compared with the well described clostridial and chromatium types.

  11. Ab initio single and multideterminant methods used in the determination of reduction potentials and magnetic properties of Rieske ferredoxins

    NASA Astrophysics Data System (ADS)

    Powers, Nathan Lee

    2008-10-01

    The [Fe2S2]2+/[Fe2S 2]+ electronic structure of seven Rieske protein active sites (bovine mitochondrial cytochrome bc1 complex, spinach chloroplast cytochrome b6f complex, Rieske-type ferredoxin associated with biphenyl dioxygenase from Burkholderia cepacia, yeast cytochrome bcl complex from Saccharomyces cerevisiae, Rieske subunit of arsenite oxidase from Alcaligenes faecalis, respiratory-type Rieske protein from Thermus thermophilus, and Rieske protein II (soxF) from Sulfolobus acidocaldarius), which lie in a reduction potential range from -150 mV to 375 mV, have been studied by both single and multi-determinant quantum mechanical methods. Calculated reduction potentials and magnetic properties are found comparable to experimental values.

  12. Flexibility of thiamine diphosphate revealed by kinetic crystallographic studies of the reaction of pyruvate-ferredoxin oxidoreductase with pyruvate.

    PubMed

    Cavazza, Christine; Contreras-Martel, Carlos; Pieulle, Laetitia; Chabrière, Eric; Hatchikian, E Claude; Fontecilla-Camps, Juan C

    2006-02-01

    Pyruvate-ferredoxin oxidoreductases (PFOR) are unique among thiamine pyrophosphate (ThDP)-containing enzymes in giving rise to a rather stable cofactor-based free-radical species upon the decarboxylation of their first substrate, pyruvate. We have obtained snapshots of unreacted and partially reacted (probably as a tetrahedral intermediate) pyruvate-PFOR complexes at different time intervals. We conclude that pyruvate decarboxylation involves very limited substrate-to-product movements but a significant displacement of the thiazolium moiety of ThDP. In this respect, PFOR seems to differ substantially from other ThDP-containing enzymes, such as transketolase and pyruvate decarboxylase. In addition, exposure of PFOR to oxygen in the presence of pyruvate results in significant inhibition of catalytic activity, both in solution and in the crystals. Examination of the crystal structure of inhibited PFOR suggests that the loss of activity results from oxime formation at the 4' amino substituent of the pyrimidine moiety of ThDP.

  13. Arabidopsis Root-Type Ferredoxin:NADP(H) Oxidoreductase 2 is Involved in Detoxification of Nitrite in Roots.

    PubMed

    Hachiya, Takushi; Ueda, Nanae; Kitagawa, Munenori; Hanke, Guy; Suzuki, Akira; Hase, Toshiharu; Sakakibara, Hitoshi

    2016-11-01

    Ferredoxin:NADP(H) oxidoreductase (FNR) plays a key role in redox metabolism in plastids. Whereas leaf FNR (LFNR) is required for photosynthesis, root FNR (RFNR) is believed to provide electrons to ferredoxin (Fd)-dependent enzymes, including nitrite reductase (NiR) and Fd-glutamine-oxoglutarate aminotransferase (Fd-GOGAT) in non-photosynthetic conditions. In some herbal species, however, most nitrate reductase activity is located in photosynthetic organs, and ammonium in roots is assimilated mainly by Fd-independent NADH-GOGAT. Therefore, RFNR might have a limited impact on N assimilation in roots grown with nitrate or ammonium nitrogen sources. AtRFNR genes are rapidly induced by application of toxic nitrite. Thus, we tested the hypothesis that RFNR could contribute to nitrite reduction in roots by comparing Arabidopsis thaliana seedlings of the wild type with loss-of-function mutants of RFNR2 When these seedlings were grown under nitrate, nitrite or ammonium, only nitrite nutrition caused impaired growth and nitrite accumulation in roots of rfnr2 Supplementation of nitrite with nitrate or ammonium as N sources did not restore the root growth in rfnr2 Also, a scavenger for nitric oxide (NO) could not effectively rescue the growth impairment. Thus, nitrite toxicity, rather than N depletion or nitrite-dependent NO production, probably causes the rfnr2 root growth defect. Our results strongly suggest that RFNR2 has a major role in reduction of toxic nitrite in roots. A specific set of genes related to nitrite reduction and the supply of reducing power responded to nitrite concomitantly, suggesting that the products of these genes act co-operatively with RFNR2 to reduce nitrite in roots.

  14. Electron spin-lattice relaxation of the (4Fe-4S) ferredoxin from B. stearothermophilus. Comparison with other iron proteins

    NASA Astrophysics Data System (ADS)

    Bertrand, Patrick; Gayda, Jean-Pierre; Rao, K. Krishna

    1982-05-01

    The temperature dependence of the electron spin-lattice relaxation time T1 of the (4Fe-4S) ferredoxin from Bacillus stearothermophilus is studied in the range 1.2 to 40 K. This dependence is similar to that observed for the (2Fe-2S) ferredoxin from Spirulina maxima and can be interpreted with the same relaxation processes [J.P. Gayda, P. Bertrand, A. Deville, C. More, G. Roger, J.F. Gibson, and R. Cammack, Biochim. Biophys. Acta 581, 15 (1979)]. In particular, between 4 and 15 K, the data are well fitted by a second-order Raman process involving three-dimensional phonons, with a Debye temperature of about 60 K (45 cm-1). This would give an estimation of the highest frequency of the vibrations which can propagate through the three-dimensional proteinic medium. In the highest temperature range (T≳30 K) the results are interpreted with an Orbach process involving an excited level of energy 120 cm-1. This process could be induced by the localized vibrations of the active site. Finally, these results are compared to those recently reported for some hemoproteins [H.J. Stapleton, J.P. Allen, C.P. Flynn, D.G. Stinson, and S.R. Kurtz, Phys. Rev. Lett. 45, 1456 (1980)]. Below 15 K, the temperature dependence of T1 for these samples is similar to that observed for the iron-sulfur proteins and may be interpreted in the same way. Our interpretation is compared to the fractal model proposed by Stapleton et al.

  15. Structural Investigations of the Ferredoxin and Terminal Oxygenase Components of the biphenyl 2,3-dioxygenase from Sphingobium yanoikuyae B1

    SciTech Connect

    Ferraro,D.; Brown, E.; Yu, C.; Parales, R.; Gibson, D.; Ramaswamy, S.

    2007-01-01

    The initial step involved in oxidative hydroxylation of monoaromatic and polyaromatic compounds by the microorganism Sphingobium yanoikuyae strain B1 (B1), previously known as Sphingomonas yanoikuyae strain B1 and Beijerinckia sp. strain B1, is performed by a set of multiple terminal Rieske non-heme iron oxygenases. These enzymes share a single electron donor system consisting of a reductase and a ferredoxin (BPDO-F{sub B1}). One of the terminal Rieske oxygenases, biphenyl 2,3-dioxygenase (BPDO-O{sub B1}), is responsible for B1's ability to dihydroxylate large aromatic compounds, such as chrysene and benzo(a)pyrene. Results: In this study, crystal structures of BPDO-O{sub B1} in both native and biphenyl bound forms are described. Sequence and structural comparisons to other Rieske oxygenases show this enzyme to be most similar, with 43.5 % sequence identity, to naphthalene dioxygenase from Pseudomonas sp. strain NCIB 9816-4. While structurally similar to naphthalene 1,2-dioxygenase, the active site entrance is significantly larger than the entrance for naphthalene 1,2-dioxygenase. Differences in active site residues also allow the binding of large aromatic substrates. There are no major structural changes observed upon binding of the substrate. BPDO-F{sub B1} has large sequence identity to other bacterial Rieske ferredoxins whose structures are known and demonstrates a high structural homology; however, differences in side chain composition and conformation around the Rieske cluster binding site are noted. Conclusion: This is the first structure of a Rieske oxygenase that oxidizes substrates with five aromatic rings to be reported. This ability to catalyze the oxidation of larger substrates is a result of both a larger entrance to the active site as well as the ability of the active site to accommodate larger substrates. While the biphenyl ferredoxin is structurally similar to other Rieske ferredoxins, there are distinct changes in the amino acids near the iron

  16. Provisional revision of American snapping shrimp allied to Alpheus floridanus Kingsley, 1878 (Crustacea: Decapoda: Alpheidae) with notes on A. floridanus africanus.

    PubMed

    Bracken-Grissom, Heather D; Felder, Darryl L

    2014-12-17

    Alpheus floridanus Kingsley, 1878 has been previously treated as a single, morphologically diverse species with a broad distribution in the eastern and western Atlantic Ocean and eastern Pacific Ocean. However, variations in morphology and color patterns, in addition to genetic evidence, have prompted futher investigation. Morphological characters, including curvature and length of the scaphocerite, number teeth on the incisor process of the mandible, number of pereopodal spines, proportions of the major chela, as well as color patterns, support recognition of several species in the Alpheus floridanus complex. Alpheus floridanus sensu stricto (s.s.) is redescribed based upon a lectotype selected from the former syntypic pair. The mutilated second specimen of the syntypic pair is identified as A. platycheirus Boone, 1927, which is fully redescribed. Three species are described as new: A. hephaestus sp. nov. from the eastern Pacific, and A. roblesi sp. nov. and A. ulalae sp. nov. from the western Atlantic. Morphological comparisions to the eastern Atlantic A. floridanus africanus Balss, 1916 are discussed, however a formal treatment of this subspecies is not the objective of this study. Our proposed taxonomic revisions of the A. floridanus complex are supported in a companion molecular genetic analysis (following paper, this volume). 

  17. Ferredoxin:NAD+ oxidoreductase of Thermoanaerobacterium saccharolyticum and its role in ethanol formation [Identification of a ferredoxin:NAD+ oxidoreductase of Thermoanaerobacterium saccharolyticum and its role in ethanol formation

    SciTech Connect

    Tian, Liang; Lo, Jonathan; Shao, Xiongjun; Zheng, Tianyong; Olson, Daniel G.; Lynd, Lee R.

    2016-09-30

    Ferredoxin:NAD+ oxidoreductase (NADH-FNOR) catalyzes the transfer of electrons from reduced ferredoxin to NAD+. This enzyme has been hypothesized to be the main enzyme responsible for ferredoxin oxidization in the NADH-based ethanol pathway in Thermoanaerobacterium saccharolyticum; however, the corresponding gene has not yet been identified. Here, we identified the Tsac_1705 protein as a candidate FNOR based on the homology of its functional domains. We then confirmed its activity in vitro with a ferredoxin-based FNOR assay. To determine its role in metabolism, the tsac_1705 gene was deleted in different strains of T. saccharolyticum. In wild-type T. saccharolyticum, deletion of tsac_1705 resulted in a 75% loss of NADH-FNOR activity, which indicated that Tsac_1705 is the main NADH-FNOR in T. saccharolyticum. When both NADH- and NADPH-linked FNOR genes were deleted, the ethanol titer decreased and the ratio of ethanol to acetate approached unity, indicative of the absence of FNOR activity. As a result, we tested the effect of heterologous expression of Tsac_1705 in Clostridium thermocellum and found improvements in both the titer and the yield of ethanol.

  18. Crystal structures of TM0549 and NE1324—two orthologs of E. coli AHAS isozyme III small regulatory subunit

    PubMed Central

    Petkowski, Janusz J.; Chruszcz, Maksymilian; Zimmerman, Matthew D.; Zheng, Heping; Skarina, Tatiana; Onopriyenko, Olena; Cymborowski, Marcin T.; Koclega, Katarzyna D.; Savchenko, Alexei; Edwards, Aled; Minor, Wladek

    2007-01-01

    Crystal structures of two orthologs of the regulatory subunit of acetohydroxyacid synthase III (AHAS, EC 2.2.1.6) from Thermotoga maritima (TM0549) and Nitrosomonas europea (NE1324) were determined by single-wavelength anomalous diffraction methods with the use of selenomethionine derivatives at 2.3 Å and 2.5 Å, respectively. TM0549 and NE1324 share the same fold, and in both proteins the polypeptide chain contains two separate domains of a similar size. Each protein contains a C-terminal domain with ferredoxin-type fold and an N-terminal ACT domain, of which the latter is characteristic for several proteins involved in amino acid metabolism. The ferredoxin domain is stabilized by a calcium ion in the crystal structure of NE1324 and by a Mg(H2O)6 2+ ion in TM0549. Both TM0549 and NE1324 form dimeric assemblies in the crystal lattice. PMID:17586771

  19. Identification of the bphA4 gene encoding ferredoxin reductase involved in biphenyl and polychlorinated biphenyl degradation in Pseudomonas sp. strain KKS102.

    PubMed Central

    Kikuchi, Y; Nagata, Y; Hinata, M; Kimbara, K; Fukuda, M; Yano, K; Takagi, M

    1994-01-01

    The nucleotide sequence of the downstream region of the bph operon from Pseudomonas sp. strain KKS102 was determined. Two open reading frames (ORF1 and ORF2) were found in this region, and the deduced amino acid sequence of ORF2 showed homology with the sequences of four ferredoxin reductases of dioxygenase systems. When this region was inserted just upstream of the bph operon, which does not contain a gene encoding ferredoxin reductase, biphenyl dioxygenase activity was detected. The 24- and 44-kDa polypeptides predicted from the two open reading frames were identified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Crude extract which contained the products of ORF2 and bphA1A2A3 showed cytochrome c reduction activity. These data clearly suggest that ORF2 encodes ferredoxin reductase. The deduced amino acid sequence of ORF1 does not show significant homology with the sequences of any other proteins in the SWISS-PROT data bank, and the function of ORF1 is unknown. Images PMID:8132464

  20. The Rnf Complex of Clostridium ljungdahlii Is a Proton-Translocating Ferredoxin:NAD(+) Oxidoreductase Essential for Autotrophic Growth

    SciTech Connect

    Tremblay, PL; Zhang, T; Dar, SA; Leang, C; Lovley, DR

    2012-12-26

    It has been predicted that the Rnf complex of Clostridium ljungdahlii is a proton-translocating ferredoxin: NAD(+) oxidoreductase which contributes to ATP synthesis by an H+-translocating ATPase under both autotrophic and heterotrophic growth conditions. The recent development of methods for genetic manipulation of C. ljungdahlii made it possible to evaluate the possible role of the Rnf complex in energy conservation. Disruption of the C. ljungdahlii rnf operon inhibited autotrophic growth. ATP synthesis, proton gradient, membrane potential, and proton motive force collapsed in the Rnf-deficient mutant with H-2 as the electron source and CO2 as the electron acceptor. Heterotrophic growth was hindered in the absence of a functional Rnf complex, as ATP synthesis, proton gradient, and proton motive force were significantly reduced with fructose as the electron donor. Growth of the Rnf-deficient mutant was also inhibited when no source of fixed nitrogen was provided. These results demonstrate that the Rnf complex of C. ljungdahlii is responsible for translocation of protons across the membrane to elicit energy conservation during acetogenesis and is a multifunctional device also implicated in nitrogen fixation. IMPORTANCE Mechanisms for energy conservation in the acetogen Clostridium ljungdahlii are of interest because of its potential value as a chassis for the production of biocommodities with novel electron donors such as carbon monoxide, syngas, and electrons derived from electrodes. Characterizing the components implicated in the chemiosmotic ATP synthesis during acetogenesis by C. ljungdahlii is a prerequisite for the development of highly productive strains. The Rnf complex has been considered the prime candidate to be the pump responsible for the formation of an ion gradient coupled with ATP synthesis in multiple acetogens. However, experimental evidence for a proton-pumping Rnf complex has been lacking. This study establishes the C. ljungdahlii Rnf complex as

  1. Physiological roles of pyruvate ferredoxin oxidoreductase and pyruvate formate-lyase in Thermoanaerobacterium saccharolyticum JW/SL-YS485

    SciTech Connect

    Zhou, Jilai; Olson, Daniel G.; Lanahan, Anthony A.; Tian, Liang; Murphy, Sean Jean-Loup; Lo, Jonathan; Lynd, Lee R.

    2015-09-15

    We report that Thermoanaerobacter saccharolyticum is a thermophilic microorganism that has been engineered to produce ethanol at high titer (30–70 g/L) and greater than 90 % theoretical yield. However, few genes involved in pyruvate to ethanol production pathway have been unambiguously identified. In T. saccharolyticum, the products of six putative pfor gene clusters and one pfl gene may be responsible for the conversion of pyruvate to acetyl-CoA. To gain insights into the physiological roles of PFOR and PFL, we studied the effect of deletions of several genes thought to encode these activities. We found that that pyruvate ferredoxin oxidoreductase enzyme (PFOR) is encoded by the pforA gene and plays a key role in pyruvate dissimilation. We further demonstrated that pyruvate formate-lyase activity (PFL) is encoded by the pfl gene. Although the pfl gene is normally expressed at low levels, it is crucial for biosynthesis in T. saccharolyticum. In pforA deletion strains, pfl expression increased and was able to partially compensate for the loss of PFOR activity. Deletion of both pforA and pfl resulted in a strain that required acetate and formate for growth and produced lactate as the primary fermentation product, achieving 88 % theoretical lactate yield. PFOR encoded by Tsac_0046 and PFL encoded by Tsac_0628 are only two routes for converting pyruvate to acetyl-CoA in T. saccharolyticum. The physiological role of PFOR is pyruvate dissimilation, whereas that of PFL is supplying C1 units for biosynthesis.

  2. EPR spectroscopic and computational characterization of the hydroxyethylidene-thiamine pyrophosphate radical intermediate of pyruvate:ferredoxin oxidoreductase.

    PubMed

    Mansoorabadi, Steven O; Seravalli, Javier; Furdui, Cristina; Krymov, Vladimir; Gerfen, Gary J; Begley, Tadhg P; Melnick, Jonathan; Ragsdale, Stephen W; Reed, George H

    2006-06-13

    The radical intermediate of pyruvate:ferredoxin oxidoreductase (PFOR) from Moorella thermoacetica was characterized using electron paramagnetic resonance (EPR) spectroscopy at X-band and D-band microwave frequencies. EPR spectra, obtained with various combinations of isotopically labeled substrate (pyruvate) and coenzyme (thiamine pyrophosphate (TPP)), were analyzed by spectral simulations. Parameters obtained from the simulations were compared with those predicted from electronic structure calculations on various radical structures. The g-values and 14N/15N-hyperfine splittings obtained from the spectra are consistent with a planar, hydroxyethylidene-thiamine pyrophosphate (HE-TPP) pi-radical, in which spin is delocalized onto the thiazolium sulfur and nitrogen atoms. The 1H-hyperfine splittings from the methyl group of pyruvate and the 13C-hyperfine splittings from C2 of both pyruvate and TPP are consistent with a model in which the pyruvate-derived oxygen atom of the HE-TPP radical forms a hydrogen bond. The hyperfine splitting constants and g-values are not compatible with those predicted for a nonplanar, sigma/n-type cation radical.

  3. Molecular and biochemical characterization of bifunctional pyruvate decarboxylases and pyruvate ferredoxin oxidoreductases from Thermotoga maritima and Thermotoga hypogea.

    PubMed

    Eram, Mohammad S; Wong, Alton; Oduaran, Erica; Ma, Kesen

    2015-12-01

    Hyperthermophilic bacteria Thermotoga maritima and Thermotoga hypogea produce ethanol as a metabolic end product, which is resulted from acetaldehyde reduction catalysed by an alcohol dehydrogenase (ADH). However, the enzyme that is involved in the production of acetaldehyde from pyruvate is not well characterized. An oxygen sensitive and coenzyme A-dependent pyruvate decarboxylase (PDC) activity was found to be present in cell free extracts of T. maritima and T. hypogea. Both enzymes were purified and found to have pyruvate ferredoxin oxidoreductase (POR) activity, indicating their bifunctionality. Both PDC and POR activities from each of the purified enzymes were characterized in regards to their optimal assay conditions including pH dependency, oxygen sensitivity, thermal stability, temperature dependency and kinetic parameters. The close relatedness of the PORs that was shown by sequence analysis could be an indication of the presence of such bifunctionality in other hyperthermophilic bacteria. This is the first report of a bifunctional PDC/POR enzyme in hyperthermophilic bacteria. The PDC and the previously reported ADHs are most likely the key enzymes catalysing the production of ethanol from pyruvate in bacterial hyperthermophiles.

  4. Purification and properties of NADH-ferredoxinNAP reductase, a component of naphthalene dioxygenase from Pseudomonas sp. strain NCIB 9816.

    PubMed Central

    Haigler, B E; Gibson, D T

    1990-01-01

    Cells of Pseudomonas sp. strain NCIB 9816, after growth with naphthalene or salicylate, contain a multicomponent enzyme system that oxidizes naphthalene to cis-(1R,2S)-dihydroxy-1,2-dihydronaphthalene. We purified one of these components to homogeneity and found it to be an iron-sulfur flavoprotein that loses the flavin cofactor during purification. Dialysis against flavin adenine dinucleotide (FAD) showed that the enzyme bound 1 mol of FAD per mol of enzyme protein. The enzyme consisted of a single polypeptide with an apparent molecular weight of 36,300. The purified protein contained 1.8 g-atoms of iron and 2.0 g-atoms of acid-labile sulfur and showed absorption maxima at 278, 340, 420, and 460 nm, with a broad shoulder at 540 nm. The purified enzyme catalyzed the reduction of cytochrome c, dichlorophenolindophenol, Nitro Blue Tetrazolium, and ferricyanide. These activities were enhanced in the presence of added FAD. The ability of the enzyme to catalyze the reduction of the ferredoxin involved in naphthalene reduction and other electron acceptors indicates that it functions as an NAD(P)H-oxidoreductase in the naphthalene dioxygenase system. The results suggest that naphthalene dioxygenase requires two proteins with three redox groups to transfer electrons from NADH to the terminal oxygenase. Images FIG. 3 PMID:2294092

  5. A deficiency in chloroplastic ferredoxin 2 facilitates effective photosynthetic capacity during long-term high light acclimation in Arabidopsis thaliana.

    PubMed

    Liu, Jun; Wang, Peng; Liu, Bing; Feng, Dongru; Zhang, Jie; Su, Jianbin; Zhang, Yang; Wang, Jin-Fa; Wang, Hong-Bin

    2013-12-01

    Photosynthetic electron transport is the major energy source for cellular metabolism in plants, and also has the potential to generate excess reactive oxygen species that cause irreversible damage to photosynthetic apparatus under adverse conditions. Ferredoxins (Fds), as the electron-distributing hub in the chloroplast, contribute to redox regulation and antioxidant defense. However, the steady-state levels of photosynthetic Fd decrease in plants when they are exposed to environmental stress conditions. To understand the effect of Fd down-regulation on plant growth, we characterized Arabidopsis thaliana plants lacking Fd2 (Fd2-KO) under long-term high light (HL) conditions. Unexpectedly, Fd2-KO plants exhibited efficient photosynthetic capacity and stable thylakoid protein complexes. At the transcriptional level, photoprotection-related genes were up-regulated more in the mutant plants, suggesting that knockout Fd2 lines possess a relatively effective photo-acclimatory responses involving enhanced plastid redox signaling. In contrast to the physiological characterization of Fd2-KO under short-term HL, the plastoquinone pool returned to a relatively balanced redox state via elevated PGR5-dependent cyclic electron flow during extended HL. fd2 pgr5 double mutant plants displayed severely impaired photosynthetic capacity under HL treatment, further supporting a role for PGR5 in adaptation to HL in the Fd2-KO plants. These results suggest potential benefits of reducing Fd levels in plants grown under long-term HL conditions.

  6. Synthesis and Antimicrobial Evaluation of Amixicile-Based Inhibitors of the Pyruvate-Ferredoxin Oxidoreductases of Anaerobic Bacteria and Epsilonproteobacteria

    PubMed Central

    Kennedy, Andrew J.; Bruce, Alexandra M.; Gineste, Catherine; Ballard, T. Eric; Olekhnovich, Igor N.; Macdonald, Timothy L.

    2016-01-01

    Amixicile is a promising derivative of nitazoxanide (an antiparasitic therapeutic) developed to treat systemic infections caused by anaerobic bacteria, anaerobic parasites, and members of the Epsilonproteobacteria (Campylobacter and Helicobacter). Amixicile selectively inhibits pyruvate-ferredoxin oxidoreductase (PFOR) and related enzymes by inhibiting the function of the vitamin B1 cofactor (thiamine pyrophosphate) by a novel mechanism. Here, we interrogate the amixicile scaffold, guided by docking simulations, direct PFOR inhibition assays, and MIC tests against Clostridium difficile, Campylobacter jejuni, and Helicobacter pylori. Docking simulations revealed that the nitro group present in nitazoxanide interacts with the protonated N4′-aminopyrimidine of thiamine pyrophosphate (TPP). The ortho-propylamine on the benzene ring formed an electrostatic interaction with an aspartic acid moiety (B456) of PFOR that correlated with improved PFOR-inhibitory activity and potency by MIC tests. Aryl substitution with electron-withdrawing groups and substitutions of the propylamine with other alkyl amines or nitrogen-containing heterocycles both improved PFOR inhibition and, in many cases, biological activity against C. difficile. Docking simulation results correlate well with mechanistic enzymology and nuclear magnetic resonance (NMR) studies that show members of this class of antimicrobials to be specific inhibitors of vitamin B1 function by proton abstraction, which is both novel and likely to limit mutation-based drug resistance. PMID:27090174

  7. (4Fe-4S)-cluster-depleted Azotobacter vinelandii ferredoxin I: a new 3Fe iron-sulfur protein

    SciTech Connect

    Stephens, P.J.; Morgan, T.V.; Devlin, F.; Penner-Hahn, J.E.; Hodgson, K.O.; Scott, R.A.; Stout, C.D.; Burgess, B.K.

    1985-09-01

    Fe(CN)6T oxidation of the aerobically isolated 7Fe Azotobacter vinelandii ferredoxin I, (7Fe)FdI, is a degradative reaction. Destruction of the (4Fe-4S) cluster occurs first, followed by destruction of the (3Fe-3S) cluster. At a Fe(CN)6T /(7Fe)FdI concentration ratio of 20, the product is a mixture of apoprotein and protein containing only a (3Fe-3S) cluster, (3Fe)FdI. This protein mixture, after partial purification, has been characterized by absorption, CD, magnetic CD, and EPR and Fe x-ray absorption spectroscopies. EPR and magnetic CD spectra provide strong evidence that the (3Fe-3S) cluster in (3Fe)FdI is essentially identical in structure to that in (7Fe)FdI. Analysis of the extended x-ray absorption fine structure (EXAFS) of (3Fe)FdI finds Fe scattering at an average Fe...Fe distance of approx. =2.7 A. The structure of the oxidized (3Fe-3S) cluster in solutions of oxidized (3Fe)FdI, and, by extension, of oxidized (7Fe)FdI, is thus different from that obtained by x-ray crystallography on oxidized (7Fe)FdI. Possible interpretations of this result are discussed.

  8. Atomic-resolution structure of the phycocyanobilin:ferredoxin oxidoreductase I86D mutant in complex with fully protonated biliverdin.

    PubMed

    Hagiwara, Yoshinori; Wada, Kei; Irikawa, Teppei; Sato, Hideaki; Unno, Masaki; Yamamoto, Ken; Fukuyama, Keiichi; Sugishima, Masakazu

    2016-10-01

    Phycocyanobilin:ferredoxin oxidoreductase (PcyA) catalyzes the reduction of biliverdin (BV) to produce phycocyanobilin, a linear tetrapyrrole pigment used for light harvesting and light sensing. Spectroscopic and HPLC analyses inidicate that BV bound to the I86D mutant of PcyA is fully protonated (BVH(+) ) and can accept an electron, but I86D is unable to donate protons for the reduction; therefore, compared to the wild-type PcyA, the I86D mutant stabilizes BVH(+) . To elucidate the structural basis of the I86D mutation, we determined the atomic-resolution structure of the I86D-BVH(+) complex and the protonation states of the essential residues Asp105 and Glu76 in PcyA. Our study revealed that Asp105 adopted a fixed conformation in the I86D mutant, although it had dual conformations in wild-type PcyA which reflected the protonation states of BV. Taken together with biochemical/spectroscopic results, our analysis of the I86D-BVH(+) structure supports the hypothesis that flexibility of Asp105 is essential for the catalytic activity of PcyA.

  9. Ferredoxin:NADP+ oxidoreductase in junction with CdSe/ZnS quantum dots: characteristics of an enzymatically active nanohybrid.

    PubMed

    Szczepaniak, Krzysztof; Worch, Remigiusz; Grzyb, Joanna

    2013-05-15

    Ferredoxin:NADP(+) oxidoreductase (FNR) is a plant and cyanobacterial photosynthetic enzyme, also found in non-photosynthetic tissues, where it is involved in redox reactions of biosynthetic pathways. In vivo it transfers electrons to nicotinamide adenine dinucleotide phosphate (NADP(+)), forming its reduced version, NADPH, while in vitro it can also use NADPH to reduce several substrates, such as ferricyanide, various quinones and nitriles. As an oxidoreductase catalyzing reaction of a broad range of substrates, FNR may be used in biotechnological processes. Quantum dots are semiconductor nanocrystals of a few to several nanometers diameter, having very useful luminescent properties. We present the spectroscopic and functional characteristics of a covalent conjugation of FNR and CdSe/ZnS quantum dots. Two types of quantum dots, of different diameter and emission maximum (550 and 650 nm), were used for comparison. Steady-state fluorescence and gel electrophoresis confirmed efficient conjugation, while fluorescence correlation spectroscopy (FCS) allowed for determination of the conjugates' radii. The nanohybrids sustained enzymatic activity; however, changes in maximal reaction rates and Michaelis constant were found. Detailed analysis of the kinetic parameters showed that the changes in the enzyme activity depend on the substrate used for activity measurement but also on the size of the quantum dots. The presented nanohybrids, as the first example using plant and photosynthetic enzyme as a protein partner, may became a tool to study photosynthesis as well as other biosynthetic and biotechnological processes, involving enzymatically catalyzed electron transfer.

  10. BIOPLUME III

    EPA Pesticide Factsheets

    BIOPLUME III is a two-dimensional finite difference model for simulating the natural attenuation of organic contaminants in groundwater due to the processes of advection, dispersion, sorption, and biodegradation.

  11. DEGRADATION OF PYRUVATE BY MICROCOCCUS LACTILYTICUS III.

    PubMed Central

    Whiteley, H. R.; McCormick, N. G.

    1963-01-01

    Whiteley, H. R. (University of Washington, Seattle) and N. G. McCormick. Degradation of pyruvate by Micrococcus lactilyticus. III. Properties and cofactor requirements of the carbon dioxide-exchange reaction. J. Bacteriol. 85:382–393. 1963.—At an acid pH, extracts of Micrococcus lactilyticus (Veillonella alcalescens) catalyze the oxidative decarboxylation of pyruvate to carbon dioxide, hydrogen, and acetyl phosphate, and the rapid exchange of carbon dioxide into the carboxyl group of pyruvate. These reactions take place only under anaerobic conditions and require phosphate (or arsenate), a reducing agent, diphosphothiamine, coenzyme A, an electron acceptor (ferredoxin, flavins, dyes, or certain inorganic anions), and a divalent cation (Co++> Mn++ > Mg++ > Fe++). High concentrations of coenzyme A and electron acceptors stimulate pyruvate breakdown but inhibit CO2 exchange. Exchange is also inhibited by p-chloromercuribenzoate but not by arsenite. Extracts rapidly lose the ability to mediate the exchange reaction after passage through diethylaminoethyl- or triethylaminoethyl-cellulose or Dowex-1; this loss in activity may be prevented by adding a reducing agent and the above cofactors. The exchange of CO2 and formate by M. lactilyticus is compared. PMID:14000380

  12. Expression of the Minor Isoform Pea Ferredoxin in Tobacco Alters Photosynthetic Electron Partitioning and Enhances Cyclic Electron Flow1[W

    PubMed Central

    Blanco, Nicolás E.; Ceccoli, Romina D.; Vía, María V. Dalla; Voss, Ingo; Segretin, María E.; Bravo-Almonacid, Fernando F.; Melzer, Michael; Hajirezaei, Mohammad-Reza; Scheibe, Renate; Hanke, Guy T.

    2013-01-01

    Ferredoxins (Fds) are ferrosulfoproteins that function as low-potential electron carriers in plants. The Fd family is composed of several isoforms that share high sequence homology but differ in functional characteristics. In leaves, at least two isoforms conduct linear and cyclic photosynthetic electron transport around photosystem I, and mounting evidence suggests the existence of at least partial division of duties between these isoforms. To evaluate the contribution of different kinds of Fds to the control of electron fluxes along the photosynthetic electron transport chain, we overexpressed a minor pea (Pisum sativum) Fd isoform (PsFd1) in tobacco (Nicotiana tabacum) plants. The transplastomic OeFd1 plants exhibited variegated leaves and retarded growth and developmental rates. Photosynthetic studies of these plants indicated a reduction in carbon dioxide assimilation rates, photosystem II photochemistry, and linear electron flow. However, the plants showed an increase in nonphotochemical quenching, better control of excitation pressure at photosystem II, and no evidence of photoinhibition, implying a better dynamic regulation to remove excess energy from the photosynthetic electron transport chain. Finally, analysis of P700 redox status during illumination confirmed that the minor pea Fd isoform promotes enhanced cyclic flow around photosystem I. The two novel features of this work are: (1) that Fd levels achieved in transplastomic plants promote an alternative electron partitioning even under greenhouse light growth conditions, a situation that is exacerbated at higher light intensity measurements; and (2) that an alternative, minor Fd isoform has been overexpressed in plants, giving new evidence of labor division among Fd isoforms. PMID:23370717

  13. Physiological roles of pyruvate ferredoxin oxidoreductase and pyruvate formate-lyase in Thermoanaerobacterium saccharolyticum JW/SL-YS485

    DOE PAGES

    Zhou, Jilai; Olson, Daniel G.; Lanahan, Anthony A.; ...

    2015-09-15

    We report that Thermoanaerobacter saccharolyticum is a thermophilic microorganism that has been engineered to produce ethanol at high titer (30–70 g/L) and greater than 90 % theoretical yield. However, few genes involved in pyruvate to ethanol production pathway have been unambiguously identified. In T. saccharolyticum, the products of six putative pfor gene clusters and one pfl gene may be responsible for the conversion of pyruvate to acetyl-CoA. To gain insights into the physiological roles of PFOR and PFL, we studied the effect of deletions of several genes thought to encode these activities. We found that that pyruvate ferredoxin oxidoreductase enzymemore » (PFOR) is encoded by the pforA gene and plays a key role in pyruvate dissimilation. We further demonstrated that pyruvate formate-lyase activity (PFL) is encoded by the pfl gene. Although the pfl gene is normally expressed at low levels, it is crucial for biosynthesis in T. saccharolyticum. In pforA deletion strains, pfl expression increased and was able to partially compensate for the loss of PFOR activity. Deletion of both pforA and pfl resulted in a strain that required acetate and formate for growth and produced lactate as the primary fermentation product, achieving 88 % theoretical lactate yield. PFOR encoded by Tsac_0046 and PFL encoded by Tsac_0628 are only two routes for converting pyruvate to acetyl-CoA in T. saccharolyticum. The physiological role of PFOR is pyruvate dissimilation, whereas that of PFL is supplying C1 units for biosynthesis.« less

  14. Non-covalent forces tune the electron transfer complex between ferredoxin and sulfite reductase to optimize enzymatic activity.

    PubMed

    Kim, Ju Yaen; Kinoshita, Misaki; Kume, Satoshi; Gt, Hanke; Sugiki, Toshihiko; Ladbury, John E; Kojima, Chojiro; Ikegami, Takahisa; Kurisu, Genji; Goto, Yuji; Hase, Toshiharu; Lee, Young-Ho

    2016-11-01

    Although electrostatic interactions between negatively charged ferredoxin (Fd) and positively charged sulfite reductase (SiR) have been predominantly highlighted to characterize complex formation, the detailed nature of intermolecular forces remains to be fully elucidated. We investigated interprotein forces for the formation of an electron transfer complex between Fd and SiR and their relationship to SiR activity using various approaches over NaCl concentrations between 0 and 400 mM. Fd-dependent SiR activity assays revealed a bell-shaped activity curve with a maximum ∼40-70 mM NaCl and a reverse bell-shaped dependence of interprotein affinity. Meanwhile, intrinsic SiR activity, as measured in a methyl viologen-dependent assay, exhibited saturation above 100 mM NaCl. Thus, two assays suggested that interprotein interaction is crucial in controlling Fd-dependent SiR activity. Calorimetric analyses showed the monotonic decrease in interprotein affinity on increasing NaCl concentrations, distinguished from a reverse bell-shaped interprotein affinity observed from Fd-dependent SiR activity assay. Furthermore, Fd:SiR complex formation and interprotein affinity were thermodynamically adjusted by both enthalpy and entropy through electrostatic and non-electrostatic interactions. A residue-based NMR investigation on the addition of SiR to (15)N-labeled Fd at the various NaCl concentrations also demonstrated that a combination of electrostatic and non-electrostatic forces stabilized the complex with similar interfaces and modulated the binding affinity and mode. Our findings elucidate that non-electrostatic forces are also essential for the formation and modulation of the Fd:SiR complex. We suggest that a complex configuration optimized for maximum enzymatic activity near physiological salt conditions is achieved by structural rearrangement through controlled non-covalent interprotein interactions.

  15. Involvement of the pyrophosphate and the 2'-phosphate binding regions of ferredoxin-NADP+ reductase in coenzyme specificity.

    PubMed

    Tejero, Jesús; Martínez-Julvez, Marta; Mayoral, Tomas; Luquita, Alejandra; Sanz-Aparicio, Julia; Hermoso, Juan A; Hurley, John K; Tollin, Gordon; Gómez-Moreno, Carlos; Medina, Milagros

    2003-12-05

    Previous studies indicated that the determinants of coenzyme specificity in ferredoxin-NADP+ reductase (FNR) from Anabaena are situated in the 2'-phosphate (2'-P) NADP+ binding region, and also suggested that other regions must undergo structural rearrangements of the protein backbone during coenzyme binding. Among the residues involved in such specificity could be those located in regions where interaction with the pyrophosphate group of the coenzyme takes place, namely loops 155-160 and 261-268 in Anabaena FNR. In order to learn more about the coenzyme specificity determinants, and to better define the structural basis of coenzyme binding, mutations in the pyrophosphate and 2'-P binding regions of FNR have been introduced. Modification of the pyrophosphate binding region, involving residues Thr-155, Ala-160, and Leu-263, indicates that this region is involved in determining coenzyme specificity and that selected alterations of these positions produce FNR enzymes that are able to bind NAD+. Thus, our results suggest that slightly different structural rearrangements of the backbone chain in the pyrophosphate binding region might determine FNR specificity for the coenzyme. Combined mutations at the 2'-P binding region, involving residues Ser-223, Arg-224, Arg-233, and Tyr-235, in combination with the residues mentioned above in the pyrophosphate binding region have also been carried out in an attempt to increase the FNR affinity for NAD+/H. However, in most cases the analyzed mutants lost the ability for NADP+/H binding and electron transfer, and no major improvements were observed with regard to the efficiency of the reactions with NAD+/H. Therefore, our results confirm that determinants for coenzyme specificity in FNR are also situated in the pyrophosphate binding region and not only in the 2'-P binding region. Such observations also suggest that other regions of the protein, yet to be identified, might also be involved in this process.

  16. Role for Ferredoxin:NAD(P)H Oxidoreductase (FprA) in Sulfate Assimilation and Siderophore Biosynthesis in Pseudomonads

    PubMed Central

    Glassing, Angela; Harper, Justin; Franklin, Michael J.

    2013-01-01

    Pyridine-2,6-bis(thiocarboxylate) (PDTC), produced by certain pseudomonads, is a sulfur-containing siderophore that binds iron, as well as a wide range of transition metals, and it affects the net hydrolysis of the environmental contaminant carbon tetrachloride. The pathway of PDTC biosynthesis has not been defined. Here, we performed a transposon screen of Pseudomonas putida DSM 3601 to identify genes necessary for PDTC production (Pdt phenotype). Transposon insertions within genes for sulfate assimilation (cysD, cysNC, and cysG [cobA2]) dominated the collection of Pdt mutations. In addition, two insertions were within the gene for the LysR-type transcriptional activator FinR (PP1637). Phenotypic characterization indicated that finR mutants were cysteine bradytrophs. The Pdt phenotype of finR mutants could be complemented by the known target of FinR regulation, fprA (encoding ferredoxin:NADP+ oxidoreductase), or by Escherichia coli cysJI (encoding sulfite reductase). These data indicate that fprA is necessary for effective sulfate assimilation by P. putida and that the effect of finR mutation on PDTC production was due to deficient expression of fprA and sulfite reduction. fprA expression in both P. putida and P. aeruginosa was found to be regulated by FinR, but in a manner dependent upon reduced sulfur sources, implicating FinR in sulfur regulatory physiology. The genes and phenotypes identified in this study indicated a strong dependence upon intracellular reduced sulfur/cysteine for PDTC biosynthesis and that pseudomonads utilize sulfite reduction enzymology distinct from that of E. coli and possibly similar to that of chloroplasts and other proteobacteria. PMID:23794620

  17. Global Positioning System III (GPS III)

    DTIC Science & Technology

    2013-12-01

    Global Positioning System III ( GPS III) As of FY 2015 President’s Budget...00-00-2013 to 00-00-2013 4. TITLE AND SUBTITLE Global Positioning System III ( GPS III) 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT...Responsible Office References Program Name Global Positioning System III ( GPS III) DoD Component Air Force

  18. Antiferromagnetic exchange interaction in the two-iron-two-sulphur ferredoxin from the blue-green alga Spirulina maxima studied with a highly sensitive magnetic balance.

    PubMed

    Petersson, L; Cammack, R; Rao, K K

    1980-03-26

    1. A highly sensitive magnetic balance of the Faraday type is described. 2. The magnetic susceptibility of the oxidized and reduced forms of the two-iron-two-sulphur ferredoxin from the blue-green alga Spirulina maxima has been measured over a wide temperature range. 3. The results can be interpreted within a simple model involving antiferromagnetically coupled iron atoms at the active site. The coupling, expressed as --J, is estimated to be 182 +/- 20/cm and 98 +5/-10 /cm for the oxidized and reduced forms, respectively.

  19. Welding III.

    ERIC Educational Resources Information Center

    Allegheny County Community Coll., Pittsburgh, PA.

    Instructional objectives and performance requirements are outlined in this course guide for Welding III, an advanced course in arc welding offered at the Community College of Allegheny County to provide students with the proficiency necessary for industrial certification. The course objectives, which are outlined first, specify that students will…

  20. Overexpressing Ferredoxins in Chlamydomonas reinhardtii Increase Starch and Oil Yields and Enhance Electric Power Production in a Photo Microbial Fuel Cell.

    PubMed

    Huang, Li-Fen; Lin, Ji-Yu; Pan, Kui-You; Huang, Chun-Kai; Chu, Ying-Kai

    2015-08-14

    Ferredoxins (FDX) are final electron carrier proteins in the plant photosynthetic pathway, and function as major electron donors in diverse redox-driven metabolic pathways. We previously showed that overexpression of a major constitutively expressed ferredoxin gene PETF in Chlamydomonas decreased the reactive oxygen species (ROS) level and enhanced tolerance to heat stress. In addition to PETF, an endogenous anaerobic induced FDX5 was overexpressed in transgenic Chlamydomonas lines here to address the possible functions of FDX5. All the independent FDX transgenic lines showed decreased cellular ROS levels and enhanced tolerance to heat and salt stresses. The transgenic Chlamydomonas lines accumulated more starch than the wild-type line and this effect increased almost three-fold in conditions of nitrogen depletion. Furthermore, the lipid content was higher in the transgenic lines than in the wild-type line, both with and without nitrogen depletion. Two FDX-overexpressing Chlamydomonas lines were assessed in a photo microbial fuel cell (PMFC); power density production by the transgenic lines was higher than that of the wild-type cells. These findings suggest that overexpression of either PETF or FDX5 can confer tolerance against heat and salt stresses, increase starch and oil production, and raise electric power density in a PMFC.

  1. Overexpressing Ferredoxins in Chlamydomonas reinhardtii Increase Starch and Oil Yields and Enhance Electric Power Production in a Photo Microbial Fuel Cell

    PubMed Central

    Huang, Li-Fen; Lin, Ji-Yu; Pan, Kui-You; Huang, Chun-Kai; Chu, Ying-Kai

    2015-01-01

    Ferredoxins (FDX) are final electron carrier proteins in the plant photosynthetic pathway, and function as major electron donors in diverse redox-driven metabolic pathways. We previously showed that overexpression of a major constitutively expressed ferredoxin gene PETF in Chlamydomonas decreased the reactive oxygen species (ROS) level and enhanced tolerance to heat stress. In addition to PETF, an endogenous anaerobic induced FDX5 was overexpressed in transgenic Chlamydomonas lines here to address the possible functions of FDX5. All the independent FDX transgenic lines showed decreased cellular ROS levels and enhanced tolerance to heat and salt stresses. The transgenic Chlamydomonas lines accumulated more starch than the wild-type line and this effect increased almost three-fold in conditions of nitrogen depletion. Furthermore, the lipid content was higher in the transgenic lines than in the wild-type line, both with and without nitrogen depletion. Two FDX-overexpressing Chlamydomonas lines were assessed in a photo microbial fuel cell (PMFC); power density production by the transgenic lines was higher than that of the wild-type cells. These findings suggest that overexpression of either PETF or FDX5 can confer tolerance against heat and salt stresses, increase starch and oil production, and raise electric power density in a PMFC. PMID:26287179

  2. Crystallization and preliminary X-ray diffraction studies of the ISC-like [2Fe–2S] ferredoxin (FdxB) from Pseudomonas putida JCM 20004

    SciTech Connect

    Iwasaki, Toshio; Ohmori, Daijiro; Shimizu, Nobutaka; Kumasaka, Takashi

    2007-12-01

    A vertebrate-type [2Fe–2S] ferredoxin (FdxB), which is probably involved in the iron–sulfur cluster-biosynthesis system of the γ-proteobacterium P. putida JCM 20004, has been crystallized in space group P6{sub 1}22. The needle-shaped crystals of recombinant FdxB diffract to 1.90 Å resolution using synchrotron radiation. The iron–sulfur (Fe–S) cluster-biosynthesis (ISC) system of the γ-proteobacterium Pseudomonas putida JCM 20004 contains a constitutively expressed vertebrate-type [2Fe–2S] ferredoxin, FdxB, which lacks the conserved free cysteine residue near the Fe–S cluster site that has been proposed to function in the catalysis of biological Fe–S cluster assembly in other bacterial homologues. Recombinant FdxB was heterologously overproduced in Escherichia coli, purified and crystallized in its oxidized form by the hanging-drop vapour-diffusion and streak-seeding methods using 1.6 M trisodium citrate dihydrate pH 6.5. The thin needle-shaped crystals diffract to 1.90 Å resolution and belong to the hexagonal space group P6{sub 1}22, with unit-cell parameters a = 87.58, c = 73.14 Å. The asymmetric unit contains one protein molecule.

  3. Constitutive expression of a plant ferredoxin-like protein (pflp) enhances capacity of photosynthetic carbon assimilation in rice (Oryza sativa).

    PubMed

    Chang, Hsiang; Huang, Hsiang-En; Cheng, Chin-Fu; Ho, Mei-Hsuan; Ger, Mang-Jye

    2017-04-01

    The plant ferredoxin-like protein (PFLP) gene, cloned from sweet peppers predicted as an electron carrier in photosynthesis, shows high homology to the Fd-I sequence of Arabidopsis thaliana, Lycopersicon esculentum, Oryza sativa and Spinacia oleracea. Most of pflp related studies focused on anti-pathogenic effects, while less understanding for the effects in photosynthesis with physiological aspects, such as photosynthesis rate, and levels of carbohydrate metabolites. This project focuses on the effects of pflp overexpression on photosynthesis by physiological evaluations of carbon assimilation with significant higher levels of carbohydrates with higher photosynthesis efficiency. In this report, two independent transgenic lines of rice plants (designated as pflp-1 and pflp-2) were generated from non-transgenic TNG67 rice plant (WT). Both transgenic pflp rice plants exhibited enhanced photosynthesis efficiency, and gas exchange rates of photosynthesis were 1.3- and 1.2-fold higher for pflp-1 and pflp-2 than WT respectively. Significantly higher electron transport rates of pflp rice plants were observed. Moreover, photosynthetic products, such as fructose, glucose, sucrose and starch contents of pflp transgenic lines were increased accordingly. Molecular evidences of carbohydrate metabolism related genes activities (osHXK5, osHXK6, osAGPL3, osAGPS2α, osSPS, ospFBPase, oscFBPase, and osSBPase) in transgenic lines were higher than those of WT. For performance of crop production, 1000-grain weight for pflp-1 and pflp-2 rice plants were 52.9 and 41.1 g that were both significantly higher than 31.6 g for WT, and panicles weights were 1.4- and 1.2-fold higher than WT. Panicle number, tiller number per plants for pflp rice plants were all significantly higher compared with those of WT where there was no significant difference observed between two pflp rice plants. Taken altogether; this study demonstrated that constitutive pflp expression can improve rice production by

  4. Le sacrum de Sterkfontein Sts 14 Q ( Australopithecus africanus): nouvelles données sur la croissance et sur l'âge osseux du spécimen (hommage à R. Broom et J.T. Robinson) . The sacrum of Sterkfontein Sts 14 Q (Australopithecus africanus): new data on the growth and on the osseus age of the specimen (homage to R. Broom and J.T. Robinson)

    NASA Astrophysics Data System (ADS)

    Berge, Christine; Gommery, Dominique

    1999-08-01

    The fossil sacrum of Sterkfontein Sts 14Q ( Australopithecus africanus) was compared with 96 human sacrums of known age so as to reveal its growth stage. Robinson (1972) noticed the presence of an immature trait (unfused intervertebral disc between S1 and S2) in this individual which in other respects is supposed to be a fully matured adult. Our study brings us to define a "sub-adult" category corresponding to a class between the ages of 16 to 25 years in modern humans. Sts 14Q had the same state of maturation, which corresponds to a post-pubertal individual which had not finished its growth concerning the sacral breadth, and probably the pelvic breadth.

  5. The FinR-regulated essential gene fprA, encoding ferredoxin NADP+ reductase: Roles in superoxide-mediated stress protection and virulence of Pseudomonas aeruginosa

    PubMed Central

    Boonma, Siriwan; Romsang, Adisak; Duang-nkern, Jintana; Atichartpongkul, Sopapan; Trinachartvanit, Wachareeporn; Vattanaviboon, Paiboon

    2017-01-01

    Pseudomonas aeruginosa has two genes encoding ferredoxin NADP(+) reductases, denoted fprA and fprB. We show here that P. aeruginosa fprA is an essential gene. However, the ΔfprA mutant could only be successfully constructed in PAO1 strains containing an extra copy of fprA on a mini-Tn7 vector integrated into the chromosome or carrying it on a temperature-sensitive plasmid. The strain containing an extra copy of the ferredoxin gene (fdx1) could suppress the essentiality of FprA. Other ferredoxin genes could not suppress the requirement for FprA, suggesting that Fdx1 mediates the essentiality of FprA. The expression of fprA was highly induced in response to treatments with a superoxide generator, paraquat, or sodium hypochlorite (NaOCl). The induction of fprA by these treatments depended on FinR, a LysR-family transcription regulator. In vivo and in vitro analysis suggested that oxidized FinR acted as a transcriptional activator of fprA expression by binding to its regulatory box, located 20 bases upstream of the fprA -35 promoter motif. This location of the FinR box also placed it between the -35 and -10 motifs of the finR promoter, where the reduced regulator functions as a repressor. Under uninduced conditions, binding of FinR repressed its own transcription but had no effect on fprA expression. Exposure to paraquat or NaOCl converted FinR to a transcriptional activator, leading to the expression of both fprA and finR. The ΔfinR mutant showed an increased paraquat sensitivity phenotype and attenuated virulence in the Drosophila melanogaster host model. These phenotypes could be complemented by high expression of fprA, indicating that the observed phenotypes of the ΔfinR mutant arose from the inability to up-regulate fprA expression. In addition, increased expression of fprB was unable to rescue essentiality of fprA or the superoxide-sensitive phenotype of the ΔfinR mutant, suggesting distinct mechanisms of the FprA and FprB enzymes. PMID:28187184

  6. Characterization of a nif-regulated flavoprotein (FprA) from Rhodobacter capsulatus. Redox properties and molecular interaction with a [2Fe-2S] ferredoxin.

    PubMed

    Jouanneau, Y; Meyer, C; Asso, M; Guigliarelli, B; Willison, J C

    2000-02-01

    A flavoprotein from Rhodobacter capsulatus was purified as a recombinant (His)6-tag fusion from an Escherichia coli clone over-expressing the fprA structural gene. The FprA protein is a homodimer containing one molecule of FMN per 48-kDa monomer. Reduction of the flavoprotein by dithionite showed biphasic kinetics, starting with a fast step of semiquinone (SQ) formation, and followed by a slow reduction of the SQ. This SQ was in the anionic form as shown by EPR and optical spectroscopies. Spectrophotometric titration gave a midpoint redox potential for the oxidized/SQ couple of Em1 = +20 mV (pH 8.0), whereas the SQ/hydroquinone couple could not be titrated due to the thermodynamic instability of SQ associated with its slow reduction process. The inability to detect the intermediate form, SQ, upon oxidative titration confirmed this instability and led to an estimate of Em2 - Em1 of > 80 mV. The reduction of SQ by dithionite was significantly accelerated when the [2Fe-2S] ferredoxin FdIV was used as redox mediator. The midpoint redox potential of this ferredoxin was determined to be -275 +/- 2 mV at pH 7.5, consistent with FdIV serving as electron donor to FprA in vivo. FdIV and FprA were found to cross-react when incubated together with the 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, giving a covalent complex with an Mr of approximately 60 000. Formation of this complex was unaffected by the redox states of the two proteins. Other [2Fe-2S] ferredoxins, including FdV and FdVI from R. capsulatus, were ineffective as electron carriers to FprA, and cross-reacted poorly with the flavoprotein. The possible function of FprA with regard to nitrogen fixation was investigated using an fprA-deleted mutant. Although nitrogenase activity was significantly reduced in the mutant compared with the wild-type strain, nitrogen fixation was apparently unaffected by the fprA deletion even under iron limitation or microaerobic conditions.

  7. Azotobacter vinelandii ferredoxin I. Aspartate 15 facilitates proton transfer to the reduced [3Fe-4S] cluster.

    PubMed

    Shen, B; Martin, L L; Butt, J N; Armstrong, F A; Stout, C D; Jensen, G M; Stephens, P J; La Mar, G N; Gorst, C M; Burgess, B K

    1993-12-05

    The [3Fe-4S]+/0 cluster of Azotobacter vinelandii ferredoxin I (AvFdI) has an unusually low and strongly pH-dependent reduction potential (E'0). The reduced cluster exists in two forms, depending upon pH, that exhibit substantially different magnetic circular dichroism (MCD) spectra. Recent studies have established that the MCD changes observed on decreasing the pH from 8.3 (alkaline form) to 6.0 (acid form) cannot be explained either by a change in spin state of the cluster (Stephens, P.J., Jensen, G.M., Devlin, F.J., Morgan, T.V., Stout, C. D., Martin, A.E., and Burgess, B.K. (1991) Biochemistry 30, 3200-3209) or by a major structural change (e.g. ligand exchange) (Stout, C.D. (1993) J. Biol. Chem. 268, 25920-25927). Here, we have examined the influence of aspartate 15 on the pH dependence of the spectroscopic and electrochemical properties of AvFdI by construction of a D15N mutant. Aspartate 15, which is salt-bridged to lysine 84 at the protein surface, is the closest ionizable residue to the [3Fe-4S] cluster. The results show that replacement of aspartate by asparagine results in an approximately 20-mV increase in E'0 for the [3Fe-4S]+/0 cluster at high pH concomitant with an approximately 0.8-pH unit decrease in the pK of the reduced form. The major pH dependence of E'0 is preserved as is the effect observed by MCD. These data eliminate the possibility that the MCD change is due to the presence of Asp-15 and support the conclusion that it originates in direct protonation of the [3Fe-4S]0 cluster, probably on a sulfide ion. Voltammetric studies show that interconversion between [3Fe-4S]+ and [3Fe-4S]0 at acidic pH involves rapid electron transfer followed by proton transfer (for reduction) and then proton transfer followed by electron transfer (for oxidation). Ionized aspartate 15 facilitates proton transfer. Thus, protonation and deprotonation are much slower for D15N relative to the native protein at pH > 5.5. Proton transfer reactions necessary for further

  8. Crystallization and preliminary X-ray diffraction analyses of the redox-controlled complex of terminal oxygenase and ferredoxin components in the Rieske nonhaem iron oxygenase carbazole 1,9a-dioxygenase

    SciTech Connect

    Matsuzawa, Jun; Aikawa, Hiroki; Umeda, Takashi; Ashikawa, Yuji; Suzuki-Minakuchi, Chiho; Kawano, Yoshiaki; Fujimoto, Zui; Okada, Kazunori; Yamane, Hisakazu; Nojiri, Hideaki

    2014-09-25

    A crystal was obtained of the complex between reduced terminal oxygenase and oxidized ferredoxin components of carbazole 1,9a-dioxygenase. The crystal belonged to space group P2{sub 1} and diffracted to 2.25 Å resolution. The initial reaction in bacterial carbazole degradation is catalyzed by carbazole 1,9a-dioxygenase, which consists of terminal oxygenase (Oxy), ferredoxin (Fd) and ferredoxin reductase components. The electron-transfer complex between reduced Oxy and oxidized Fd was crystallized at 293 K using the hanging-drop vapour-diffusion method with PEG 3350 as the precipitant under anaerobic conditions. The crystal diffracted to a maximum resolution of 2.25 Å and belonged to space group P2{sub 1}, with unit-cell parameters a = 97.3, b = 81.6, c = 116.2 Å, α = γ = 90, β = 100.1°. The V{sub M} value is 2.85 Å{sup 3} Da{sup −1}, indicating a solvent content of 56.8%.

  9. Direct interaction with ACR11 is necessary for post-transcriptional control of GLU1-encoded ferredoxin-dependent glutamate synthase in leaves

    PubMed Central

    Takabayashi, Atsushi; Niwata, Akihiro; Tanaka, Ayumi

    2016-01-01

    Because it plays an essential role in nitrogen (N) assimilation and photorespiration, the glutamine synthetase (GS)/glutamate synthase (GOGAT) system is widely accepted as occupying a central position in leaf N metabolism. However, the regulation of GOGAT at the post-transcriptional level is poorly understood. Here, we show that ACR11, an ACT (acronym for aspartate kinase, chorismate mutase, and TyrA) domain-containing family protein, interacts with Glu1-encoded ferredoxin (Fd)-GOGAT in Arabidopsis chloroplasts. In addition, Arabidopsis acr11 mutants have lost the capability to control Fd-GOGAT levels in response to light/dark diurnal cycles, nitrogen inputs, and changes in photorespiratory activity. Considering that ACR11 has putative glutamine-binding domains, our results indicate that ACR11 is necessary for post-transcriptional control of leaf Glu1-encoded Fd-GOGAT. This regulation takes place through direct interaction of ACR11 and Fd-GOGAT, possibly in an allosteric manner. PMID:27411448

  10. Identification of a Novel Nonstructural Protein, VP9, from White Spot Syndrome Virus: Its Structure Reveals a Ferredoxin Fold with Specific Metal Binding Sites

    SciTech Connect

    Liu,Y.; Wu, J.; Song, J.; Sivaraman, J.; Hew, C.

    2006-01-01

    White spot syndrome virus (WSSV) is a major pathogen in shrimp aquaculture. VP9, a full-length protein of WSSV, encoded by open reading frame wsv230, was identified for the first time in the infected Penaeus monodon shrimp tissues, gill, and stomach as a novel, nonstructural protein by Western blotting, mass spectrometry, and immunoelectron microscopy. Real-time reverse transcription-PCR demonstrated that the transcription of VP9 started from the early to the late stage of WSSV infection as a major mRNA species. The structure of full-length VP9 was determined by both X-ray and nuclear magnetic resonance (NMR) techniques. It is the first structure to be reported for WSSV proteins. The crystal structure of VP9 revealed a ferredoxin fold with divalent metal ion binding sites. Cadmium sulfate was found to be essential for crystallization. The Cd2+ ions were bound between the monomer interfaces of the homodimer. Various divalent metal ions have been titrated against VP9, and their interactions were analyzed using NMR spectroscopy. The titration data indicated that VP9 binds with both Zn2+ and Cd2+. VP9 adopts a similar fold as the DNA binding domain of the papillomavirus E2 protein. Based on our present investigations, we hypothesize that VP9 might be involved in the transcriptional regulation of WSSV, a function similar to that of the E2 protein during papillomavirus infection of the host cells.

  11. The involvement of the nif-associated ferredoxin-like genes fdxA and fdxN of Herbaspirillum seropedicae in nitrogen fixation.

    PubMed

    Souza, André L F; Invitti, Adriana L; Rego, Fabiane G M; Monteiro, Rose A; Klassen, Giseli; Souza, Emanuel M; Chubatsu, Leda S; Pedrosa, Fábio O; Rigo, Liu U

    2010-02-01

    The pathway of electron transport to nitrogenase in the endophytic beta-Proteobacterium Herbaspirillum seropedicae has not been characterized. We have generated mutants in two nif-associated genes encoding putative ferredoxins, fdxA and fdxN. The fdxA gene is part of the operon nifHDKENXorf1orf2fdxAnifQmodABC and is transcribed from the nifH promoter, as revealed by lacZ gene fusion. The fdxN gene is probably cotranscribed with the nifB gene. Mutational analysis suggests that the FdxA protein is essential for maximum nitrogenase activity, since the nitrogenase activity of the fdxA mutant strain was reduced to about 30% of that of the wild-type strain. In addition, the fdxA mutation had no effect on the nitrogenase switch-off in response to ammonium. Nitrogenase activity of a mutant strain lacking the fdxN gene was completely abolished. This phenotype was reverted by complementation with fdxN expressed under lacZ promoter control. The results suggest that the products of both the fdxA and fdxN genes are probably involved in electron transfer during nitrogen fixation.

  12. Evaluation of the protection exerted by Pisum sativum Ferredoxin-NADP(H) Reductase against injury induced by hypothermia on Cos-7 cells.

    PubMed

    Pucci Molineris, M; Di Venanzio, G; Mamprin, M E; Mediavilla, M G

    2013-08-01

    Hypothermia is employed as a method to diminish metabolism rates and preserve tissues and cells. However, low temperatures constitute a stress that produces biochemical changes whose extension depends on the duration and degree of cold exposure and is manifested when physiological temperature is restored. For many cellular types, cold induces an oxidative stress that is dependent on the elevation of intracellular iron, damages macromolecules, and is prevented by the addition of iron chelators. Pisum sativum Ferredoxin-NADP(H) Reductase (FNR) has been implicated in protection from injury mediated by intracellular iron increase and successfully used to reduce oxidative damage on bacterial, plant and mammalian systems. In this work, FNR was expressed in Cos-7 cells; then, they were submitted to cold incubation and iron overload to ascertain whether this enzyme was capable of diminishing the harm produced by these challenges. Contrary to expected, FNR was not protective and even exacerbated the damage under certain circumstances. It was also found that the injury induced by hypothermia in Cos-7 cells presented both iron-dependent and iron-independent components of damage when cells were actively dividing but only iron-independent component when cells were in an arrested state. This is in agreement with previous findings which showed that iron-dependent damage is also an energy-dependent process.

  13. Silencing of SlFTR-c, the catalytic subunit of ferredoxin:thioredoxin reductase, induces pathogenesis-related genes and pathogen resistance in tomato plants.

    PubMed

    Lim, Chan Ju; Kim, Woong Bom; Lee, Bok-Sim; Lee, Ha Youn; Kwon, Tae-Ho; Park, Jeong Mee; Kwon, Suk-Yoon

    2010-09-03

    As a heterodimeric protein, ferredoxin:thioredoxin reductase (FTR) catalyses the light-dependant activation of several photosynthetic enzymes. The active site of the catalytic subunit of FTR contains a redox-active disulfide and a [4Fe-4S] center. We isolated the catalytic subunit gene of FTR, designated SlFTR-c, from tomato (Solanum lycopersicum L.). SlFTR-c transcripts were detected in all tissues examined, including roots, leaves, flowers, fruits, and seeds. Interestingly, virus-induced gene silencing (VIGS) of SlFTR-c resulted in necrotic lesions with typical cell death symptoms and reactive oxygen species (ROS) production in tomato leaves. Moreover, these SlFTR-c-silenced plants displayed enhanced disease resistance against bacterial pathogens, specifically Pseudomonas syringae pv. tomato DC3000, by the induction of defense-related genes (SlPR-1, SlPR-2, SlPR-5, SlGlucA, SlChi3, and SlChi9). Taken together, it seems that SlFTR-c works as a regulator of programmed cell death (PCD) and pathogen resistance in tomato plants.

  14. Dissection of hydrogen bond interaction network around an iron-sulfur cluster by site-specific isotope labeling of hyperthermophilic archaeal Rieske-type ferredoxin.

    PubMed

    Iwasaki, Toshio; Fukazawa, Risako; Miyajima-Nakano, Yoshiharu; Baldansuren, Amgalanbaatar; Matsushita, Shinichi; Lin, Myat T; Gennis, Robert B; Hasegawa, Kazuya; Kumasaka, Takashi; Dikanov, Sergei A

    2012-12-05

    The electronic structure and geometry of redox-active metal cofactors in proteins are tuned by the pattern of hydrogen bonding with the backbone peptide matrix. In this study we developed a method for selective amino acid labeling of a hyperthermophilic archaeal metalloprotein with engineered Escherichia coli auxotroph strains, and we applied this to resolve the hydrogen bond interactions with the reduced Rieske-type [2Fe-2S] cluster by two-dimensional pulsed electron spin resonance technique. Because deep electron spin-echo envelope modulation of two histidine (14)N(δ) ligands of the cluster decreased non-coordinating (15)N signal intensities via the cross-suppression effect, an inverse labeling strategy was employed in which (14)N amino acid-labeled archaeal Rieske-type ferredoxin samples were examined in an (15)N-protein background. This has directly identified Lys45 N(α) as providing the major pathway for the transfer of unpaired electron spin density from the reduced cluster by a "through-bond" mechanism. All other backbone peptide nitrogens interact more weakly with the reduced cluster. The extension of this approach will allow visualizing the three-dimensional landscape of preferred pathways for the transfer of unpaired spin density from a paramagnetic metal center onto the protein frame, and will discriminate specific interactions by a "through-bond" mechanism from interactions which are "through-space" in various metalloproteins.

  15. Identification and cloning of two immunogenic Clostridium perfringens proteins, elongation factor Tu (EF-Tu) and pyruvate:ferredoxin oxidoreductase (PFO) of C. perfringens.

    PubMed

    Lee, Kyungwoo; Lillehoj, Hyun S; Li, Guangxing; Park, Myeong-Seon; Jang, Seung I; Jeong, Wooseog; Jeoung, Hye-Young; An, Dong-Jun; Lillehoj, Erik P

    2011-12-01

    Clostridium-related poultry diseases such as necrotic enteritis (NE) and gangrenous dermatitis (GD) cause substantial economic losses on a global scale. Two antigenic Clostridium perfringens proteins, elongation factor Tu (EF-Tu) and pyruvate:ferredoxin oxidoreductase (PFO), were identified by reaction with immune sera from commercial meat-type chickens with clinical outbreak of Clostridium infections. In addition to the genes encoding EF-Tu and PFO, C. perfringens alpha-toxin and necrotic enteritis B-like (NetB) toxin were also expressed in Escherichia coli and their corresponding recombinant proteins were purified. Using the four recombinant proteins as target antigens in ELISA immunoassays, high serum antibody titers were observed not only in chickens with clinical signs of Clostridium infections, but also in apparently healthy animals from the same disease-endemic farm. By contrast, no antibodies against any of the proteins were present in the serum of a specific pathogen-free bird. In ELISA using recombinant proteins of C. perfringens, the levels of anti-bacterial protein antibodies were also higher in chickens which were experimentally induced to show NE clinical signs after co-infection with C. perfringens and Eimeria maxima compared with uninfected controls. These results show that two antigenic C. perfringens proteins, EF-Tu and PFO can be useful detection antigens for C. perfringens-afflicted infections in commercial poultry.

  16. LIGHT-INDUCED RICE1 Regulates Light-Dependent Attachment of LEAF-TYPE FERREDOXIN-NADP+ OXIDOREDUCTASE to the Thylakoid Membrane in Rice and Arabidopsis

    PubMed Central

    Yang, Chao; Lin, Hongwei; Wang, Lingling; He, Yi; Ding, Xiaomeng; Grabsztunowicz, Magda; Chen, Tao; Liu, Yu; Wu, Zhongchang; Wu, Yunrong; Wu, Ping; Mo, Xiaorong

    2016-01-01

    LIR1 (LIGHT-INDUCED RICE1) encodes a 13-kD, chloroplast-targeted protein containing two nearly identical motifs of unknown function. LIR1 is present in the genomes of vascular plants, mosses, liverworts, and algae, but not in cyanobacteria. Using coimmunoprecipitation assays, pull-down assays, and yeast two-hybrid analyses, we showed that LIR1 interacts with LEAF-TYPE FERREDOXIN-NADP+ OXIDOREDUCTASE (LFNR), an essential chloroplast enzyme functioning in the last step of photosynthetic linear electron transfer. LIR1 and LFNR formed high molecular weight thylakoid protein complexes with the TIC62 and TROL proteins, previously shown to anchor LFNR to the membrane. We further showed that LIR1 increases the affinity of LFNRs for TIC62 and that the rapid light-triggered degradation of the LIR1 coincides with the release of the LFNR from the thylakoid membrane. Loss of LIR1 resulted in a marked decrease in the accumulation of LFNR-containing thylakoid protein complexes without a concomitant decrease in total LFNR content. In rice (Oryza sativa), photosynthetic capacity of lir1 plants was slightly impaired, whereas no such effect was observed in Arabidopsis thaliana knockout mutants. The consequences of LIR1 deficiency in different species are discussed. PMID:26941088

  17. Characterization of BciB: a ferredoxin-dependent 8-vinyl-protochlorophyllide reductase from the green sulfur bacterium Chloroherpeton thalassium.

    PubMed

    Saunders, Allison H; Golbeck, John H; Bryant, Donald A

    2013-11-26

    Two enzymes, BciA and BciB, are known to reduce the C-8 vinyl group of 8-vinyl protochlorophyllide, producing protochlorophyllide a, during the synthesis of chlorophylls and bacteriochlorophylls in chlorophototrophic bacteria. BciA from the green sulfur bacterium Chlorobaculum tepidum reduces the C-8 vinyl group using NADPH as the reductant. Cyanobacteria and some other chlorophototrophs have a second, nonhomologous type of 8-vinyl reductase, BciB, but the biochemical properties of this enzyme have not yet been described. In this study, the bciB gene of the green sulfur bacterium Chloroherpeton thalassium was expressed in Escherichia coli , and the recombinant protein was purified and characterized. Recombinant BciB binds a flavin adenine dinucleotide cofactor, and EPR spectroscopy as well as quantitative analyses of bound iron and sulfide suggest that BciB binds two [4Fe-4S] clusters, one of which may not be essential for the activity of the enzyme. Using electrons provided by reduced ferredoxin or dithionite, recombinant BciB was active and reduced the 8-vinyl moiety of the substrate, 8-vinyl protochlorophyllide, producing protochlorophyllide a. A structural model for BciB based on a recent structure for the FrhB subunit of F420-reducing [NiFe]-hydrogenase of Methanothermobacter marburgensis is proposed. Possible reasons for the occurrence and distribution of BciA and BciB among various chlorophototrophs are discussed.

  18. Prevalence of Theileria equi and Babesia caballi as well as the identification of associated ticks in sympatric Grevy's zebras (Equus grevyi) and donkeys (Equus africanus asinus) in northern Kenya.

    PubMed

    Hawkins, Elaine; Kock, Richard; McKeever, Declan; Gakuya, Francis; Musyoki, Charles; Chege, Stephen M; Mutinda, Mathew; Kariuki, Edward; Davidson, Zeke; Low, Belinda; Skilton, Robert A; Njahira, Moses N; Wamalwa, Mark; Maina, Elsie

    2015-01-01

    The role of equine piroplasmosis as a factor in the population decline of the Grevy's zebra is not known. We determined the prevalence of Babesia caballi and Theileria equi in cograzing Grevy's zebras (Equus grevyi) and donkeys (Equus africanus asinus) in northern Kenya and identified the associated tick vectors. Blood samples were taken from 71 donkeys and 16 Grevy's zebras from March to May 2011. A nested PCR reaction using 18s ribosomal (r)RNA primers on 87 blood spots showed 72% (51/71; 95% confidence interval [CI] 60.4-81.0%) of donkeys and 100% (16/16; 95% CI, 77.3-100%) of Grevy's zebras were T. equi positive. No samples were positive for B. caballi. Sequence comparison using the National Center for Biotechnology Information's basic local alignment search tool identified homologous 18s rRNA sequences with a global geographic spread. The T. equi-derived sequences were evaluated using Bayesian approaches with independent Metropolis-coupled Markov chain Monte Carlo runs. The sequences clustered with those found in Sudan, Croatia, Mongolia, and the US, with statistical support greater than 80% for the two main clades. Hyalomma tick species were found on both donkeys and Grevy's zebras, whereas Rhipicephalus pulchellus was found exclusively on Grevy's zebras and Hyalomma marginatum rupfipes on donkeys. The prevalence of T. equi was 100% in Grevy's zebras and 72% in donkeys with common tick vectors identified. Our results suggest that donkeys and Grevy's zebras can be asymptomatic carriers and that piroplasmosis is endemic in the study area.

  19. Arabidopsis Tic62 and Ferredoxin-NADP(H) Oxidoreductase Form Light-Regulated Complexes That Are Integrated into the Chloroplast Redox Poise[C][W

    PubMed Central

    Benz, J.P.; Stengel, A.; Lintala, M.; Lee, Y.-H.; Weber, A.; Philippar, K.; Gügel, I.L.; Kaieda, S.; Ikegami, T.; Mulo, P.; Soll, J.; Bölter, B.

    2009-01-01

    Translocation of nuclear-encoded preproteins across the inner envelope of chloroplasts is catalyzed by the Tic translocon, consisting of Tic110, Tic40, Tic62, Tic55, Tic32, Tic20, and Tic22. Tic62 was proposed to act as a redox sensor of the complex because of its redox-dependent shuttling between envelope and stroma and its specific interaction with the photosynthetic protein ferredoxin-NADP(H) oxidoreductase (FNR). However, the nature of this close relationship so far remained enigmatic. A putative additional localization of Tic62 at the thylakoids mandated further studies examining how this feature might be involved in the respective redox sensing pathway and the interaction with its partner protein. Therefore, both the association with FNR and the physiological role of the third, thylakoid-bound pool of Tic62 were investigated in detail. Coexpression analysis indicates that Tic62 has similar expression patterns as genes involved in photosynthetic functions and protein turnover. At the thylakoids, Tic62 and FNR form high molecular weight complexes that are not involved in photosynthetic electron transfer but are dynamically regulated by light signals and the stromal pH. Structural analyses reveal that Tic62 binds to FNR in a novel binding mode for flavoproteins, with a major contribution from hydrophobic interactions. Moreover, in absence of Tic62, membrane binding and stability of FNR are drastically reduced. We conclude that Tic62 represents a major FNR interaction partner not only at the envelope and in the stroma, but also at the thylakoids of Arabidopsis thaliana and perhaps all flowering plants. Association with Tic62 stabilizes FNR and is involved in its dynamic and light-dependent membrane tethering. PMID:20040542

  20. Pseudomonas aeruginosa IscR-Regulated Ferredoxin NADP(+) Reductase Gene (fprB) Functions in Iron-Sulfur Cluster Biogenesis and Multiple Stress Response

    PubMed Central

    Romsang, Adisak; Duang-nkern, Jintana; Wirathorn, Wilaiwan; Vattanaviboon, Paiboon; Mongkolsuk, Skorn

    2015-01-01

    P. aeruginosa (PAO1) has two putative genes encoding ferredoxin NADP(+) reductases, denoted fprA and fprB. Here, the regulation of fprB expression and the protein’s physiological roles in [4Fe-4S] cluster biogenesis and stress protection are characterized. The fprB mutant has defects in [4Fe-4S] cluster biogenesis, as shown by reduced activities of [4Fe-4S] cluster-containing enzymes. Inactivation of the gene resulted in increased sensitivity to oxidative, thiol, osmotic and metal stresses compared with the PAO1 wild type. The increased sensitivity could be partially or completely suppressed by high expression of genes from the isc operon, which are involved in [Fe-S] cluster biogenesis, indicating that stress sensitivity in the fprB mutant is partially caused by a reduction in levels of [4Fe-4S] clusters. The pattern and regulation of fprB expression are in agreement with the gene physiological roles; fprB expression was highly induced by redox cycling drugs and diamide and was moderately induced by peroxides, an iron chelator and salt stress. The stress-induced expression of fprB was abolished by a deletion of the iscR gene. An IscR DNA-binding site close to fprB promoter elements was identified and confirmed by specific binding of purified IscR. Analysis of the regulation of fprB expression supports the role of IscR in directly regulating fprB transcription as a transcription activator. The combination of IscR-regulated expression of fprB and the fprB roles in response to multiple stressors emphasizes the importance of [Fe-S] cluster homeostasis in both gene regulation and stress protection. PMID:26230408

  1. Identification and characterization of PshB, the dicluster ferredoxin that harbors the terminal electron acceptors F(A) and F(B) in Heliobacterium modesticaldum.

    PubMed

    Heinnickel, Mark; Shen, Gaozhong; Golbeck, John H

    2007-03-06

    The Type I homodimeric photosynthetic reaction center found in anaerobic gram-positive bacteria of the genus Heliobacteriaceae incorporates FA- and FB-like iron-sulfur clusters similar to those found in Photosystem I as terminal electron acceptors. We recently isolated the PshB protein that harbors the iron-sulfur clusters from the reaction centers of Heliobacterium modesticaldum. Here, we report the cloning of a candidate gene and the properties of its product. Genuine PshB was dissociated from the reaction center with 1 M NaCl and purified using an affinity strategy. After acquiring its N-terminal amino acid sequence, an fd2-like gene encoding a 5.5-kDa dicluster ferredoxin was identified as a candidate for PshB. The Fd2-like apoprotein was expressed in Escherichia coli with a His tag, and the Fe/S clusters were inserted using inorganic reagents. The optical absorbance and EPR spectra of the Fd2-like holoprotein were similar to those of genuine PshB. The Fd2-like holoprotein was coeluted with P798-FX cores on both G-75 gel filtration and Ni affinity columns. Consistent with binding, the EPR resonances at g = 2.067, 1.933, and 1.890 from [FA/FB]- were restored after illumination at 15 K, and the long-lived, room-temperature charge recombination kinetics between P798+ and [FA/FB]- reappeared on a laser flash. These characteristics indicate that the long-sought gene and polypeptide harboring the FA- and FB-like clusters in heliobacteria have been identified. The amino acid sequence of PshB indicates an entirely different mode of binding with the reaction center core than PsaC, its counterpart in Photosystem I.

  2. Functional Inactivation of Putative Photosynthetic Electron Acceptor Ferredoxin C2 (FdC2) Induces Delayed Heading Date and Decreased Photosynthetic Rate in Rice.

    PubMed

    Zhao, Juan; Qiu, Zhennan; Ruan, Banpu; Kang, Shujing; He, Lei; Zhang, Sen; Dong, Guojun; Hu, Jiang; Zeng, Dali; Zhang, Guangheng; Gao, Zhenyu; Ren, Deyong; Hu, Xingming; Chen, Guang; Guo, Longbiao; Qian, Qian; Zhu, Li

    2015-01-01

    Ferredoxin (Fd) protein as unique electron acceptor, involved in a variety of fundamental metabolic and signaling processes, which is indispensable for plant growth. The molecular mechanisms of Fd such as regulation of electron partitioning, impact of photosynthetic rate and involvement in the carbon fixing remain elusive in rice. Here we reported a heading date delay and yellowish leaf 1 (hdy1) mutant derived from Japonica rice cultivar "Nipponbare" subjected to EMS treatment. In the paddy field, the hdy1 mutant appeared at a significantly late heading date and had yellow-green leaves during the whole growth stage. Further investigation indicated that the abnormal phenotype of hdy1 was connected with depressed pigment content and photosynthetic rate. Genetic analysis results showed that the hdy1 mutant phenotype was caused by a single recessive nuclear gene mutation. Map-based cloning revealed that OsHDY1 is located on chromosome 3 and encodes an ortholog of the AtFdC2 gene. Complementation and overexpression, transgenic plants exhibited the mutant phenotype including head date, leaf color and the transcription levels of the FdC2 were completely rescued by transformation with OsHDY1. Real-time PCR revealed that the expression product of OsHDY1 was detected in almost all of the organs except root, whereas highest expression levels were observed in seeding new leaves. The lower expression levels of HDY1 and content of iron were detected in hdy1 than WT's. The FdC2::GFP was detected in the chloroplasts of rice. Real-time PCR results showed that the expression of many photosynthetic electron transfer related genes in hdy1 were higher than WT. Our results suggest that OsFdC2 plays an important role in photosynthetic rate and development of heading date by regulating electron transfer and chlorophyll content in rice.

  3. Global Positioning System III (GPS III)

    DTIC Science & Technology

    2015-12-01

    from the SV Bus, specifically the Scalable Power Regulation Unit and is being amplified by the solar arrays which act as highly efficient antennas. To...Military Operations in Urban Terrain; Defense-Wide Mission Support; Air Mobility; and Space Launch Orbital Support. For military users, the GPS III...Service: The GPS III program will provide O&S for on- orbit support through the Launch and On- Orbit Support contract. For Space Vehicle (SV)01 and

  4. Multinuclear magnetic resonance studies of the 2Feter dot 2S sup * ferredoxin from Anabaena species strain PCC 7120. 1. Sequence-specific hydrogen-1 resonance assignments and secondary structure in solution of the oxidized form

    SciTech Connect

    Oh, Byung-Ha; Markley, J.L. )

    1990-04-24

    Complete sequence-specific assignments were determined for the diamagnetic {sup 1}H resonances from Anabaena 7120 ferredoxin. A novel assignment procedure was followed whose first step was the identification of the {sup 13}C spin systems of the amino acids by a {sup 13}C({sup 13}C) double quantum correlation experiment. Then, the {sup 1}H spin systems of the amino acids were identified from the {sup 13}C spin systems by means of direct and relayed {sup 1}H({sup 13}C) single-bond correlations. The sequential resonance assignments were based mainly on conventional interresidue {sup 1}H{sup {alpha}}{sub i}-{sup 1}H{sup N}{sub i+1} NOE connectivities. Resonances from 18 residues were not resolved in two-dimensional {sup 1}H NMR spectra. When these residues were mapped onto the X-ray crystal structure of the homologous ferredoxin from Spirulina platensis, it was found that they correspond to amino acids close to the paramagnetic 2Fe{center dot}2S cluster. Cross peaks in two-dimensional homonuclear {sup 1}H NMR spectra were not observed for any protons closer than about 7.8 {angstrom} to both iron atoms. Secondary structural features identified in solution include two antiparallel {beta}-sheets, one parallel {beta}-sheet, and one {alpha}-helix.

  5. Electron Transport in a Dioxygenase-Ferredoxin Complex: Long Range Charge Coupling between the Rieske and Non-Heme Iron Center

    PubMed Central

    Jono, Ryota; Shimizu, Kentaro

    2016-01-01

    Dioxygenase (dOx) utilizes stereospecific oxidation on aromatic molecules; consequently, dOx has potential applications in bioremediation and stereospecific oxidation synthesis. The reactive components of dOx comprise a Rieske structure Cys2[2Fe-2S]His2 and a non-heme reactive oxygen center (ROC). Between the Rieske structure and the ROC, a universally conserved Asp residue appears to bridge the two structures forming a Rieske-Asp-ROC triad, where the Asp is known to be essential for electron transfer processes. The Rieske and ROC share hydrogen bonds with Asp through their His ligands; suggesting an ideal network for electron transfer via the carboxyl side chain of Asp. Associated with the dOx is an itinerant charge carrying protein Ferredoxin (Fdx). Depending on the specific cognate, Fdx may also possess either the Rieske structure or a related structure known as 4-Cys-[2Fe-2S] (4-Cys). In this study, we extensively explore, at different levels of theory, the behavior of the individual components (Rieske and ROC) and their interaction together via the Asp using a variety of density function methods, basis sets, and a method known as Generalized Ionic Fragment Approach (GIFA) that permits setting up spin configurations manually. We also report results on the 4-Cys structure for comparison. The individual optimized structures are compared with observed spectroscopic data from the Rieske, 4-Cys and ROC structures (where information is available). The separate pieces are then combined together into a large Rieske-Asp-ROC (donor/bridge/acceptor) complex to estimate the overall coupling between individual components, based on changes to the partial charges. The results suggest that the partial charges are significantly altered when Asp bridges the Rieske and the ROC; hence, long range coupling through hydrogen bonding effects via the intercalated Asp bridge can drastically affect the partial charge distributions compared to the individual isolated structures. The

  6. SUPERSTARS III: K-2.

    ERIC Educational Resources Information Center

    North Carolina State Dept. of Public Education, Raleigh.

    SUPERSTARS III is a K-8 program designed as an enrichment opportunity for self-directed learners in mathematics. The basic purpose of SUPERSTARS III is to provide the extra challenge that self-motivated students need in mathematics and to do so in a structured, long-term program that does not impinge on the normal classroom routine or the…

  7. Detection and classification of hyperfine-shifted 1H, 2H, and 15N resonances of the Rieske ferredoxin component of toluene 4-monooxygenase.

    PubMed

    Xia, B; Pikus, J D; Xia, W; McClay, K; Steffan, R J; Chae, Y K; Westler, W M; Markley, J L; Fox, B G

    1999-01-12

    T4MOC is a 12.3 kDa soluble Rieske ferredoxin that is obligately required for electron transfer between the oxidoreductase and diiron hydroxylase components of toluene 4-monooxygenase from Pseudomonas mendocina KR1. Our preliminary 1H NMR studies of oxidized and reduced T4MOC [Markley, J. L., Xia, B., Chae, Y. K., Cheng, H., Westler, W. M., Pikus, J. D., and Fox, B. G. (1996) in Protein Structure Function Relationships (Zaidi, Z., and Smith, D., Eds.) pp 135-146, Plenum Press, London] revealed the presence of hyperfine-shifted 1H resonances whose short relaxation times made it impractical to use nuclear Overhauser effect (NOE) measurements for assignment purposes. We report here the use of selective isotopic labeling to analyze the hyperfine-shifted 1H, 2H, and 15N signals from T4MOC. Selective deuteration led to identification of signals from the four Hbeta atoms of cluster ligands C45 and C64 in the oxidized and reduced forms of T4MOC. In the reduced state, the Curie temperature dependence of the Hbeta protons corresponded to that predicted from the simple vector spin-coupling model for nuclei associated with the localized ferric site. The signal at 25.5 ppm in the 1H spectrum of reduced T4MOC was assigned on the basis of selective 2H labeling to the His Hepsilon1 atom of one of the cluster ligands (H47 or H67). This assignment was corroborated by a one bond 1H-13C correlation (at 25.39 ppm 1H and 136.11 ppm 13C) observed in spectra of [U-13C]T4MOC with a 1H-13C coupling constant of approximately 192 Hz. The carbon chemical shift and one bond coupling constant are those expected for 1Hepsilon1-13Cepsilon1 in the imidazolium ring of histidine and are inconsistent with values expected for cysteine 1Halpha-13Calpha. The His Hepsilon1 proton exhibited weak Curie temperature dependence from 283 to 303 K, contrary to the anti-Curie temperature dependence predicted from the spin coupling model for nuclei associated with the localized ferrous site. A 1H peak at -12.3 ppm

  8. Antithrombin III blood test

    MedlinePlus

    ... AT III) is a protein that helps control blood clotting. A blood test can determine the amount of ... may mean you have an increased risk of blood clotting. This can occur when there is not enough ...

  9. Type III burst pair

    NASA Astrophysics Data System (ADS)

    Ning, Zongjun; Fu, Qijun; Lu, Quankang

    2000-05-01

    We present a special solar radio burst detected on 5 January 1994 using the multi-channel (50) spectrometer (1.0-2.0 GHz) of the Beijing Astronomical Observatory (BAO). Sadly, the whole event could not be recorded since it had a broader bandwidth than the limit range of the instrument. The important part was obtained, however. The event is composed of a normal drift type III burst on the lower frequency side and a reverse drift type III burst appearing almost simultaneously on the high side. We call the burst type III a burst pair. It is a typical characteristic of two type III bursts that they are morphologically symmetric about some frequency from 1.64 GHz to 1.78 GHz on the dynamic spectra records, which indicates that there are two different electron beams from the same acceleration region travelling simultaneously in opposite directions (upward and downward). A magnetic reconnection mode is a nice interpretation of type III burst pair since the plasma beta β~=0.01 is much less than 1 and the beams have velocity of about 1.07×10^8 cm s^-1 after leaving the reconnection region if we assume that the ambient magnetic field strength is about 100 G.

  10. Type III burst pair.

    NASA Astrophysics Data System (ADS)

    Zongjun, Ning; Fu, Qijun; Quankang, Lu

    2000-05-01

    Presents a special solar radio burst detected on 5 January 1994 using the multi-channel (50) spectrometer (1.0 - 2.0 GHz) of the Beijing Astronomical Observatory. Sadly, the whole event could not be recorded since it had a broader bandwidth than the limit range of the instrument. The important part was obtained, however. The event is composed of a normal drift type III burst on the lower frequency side and a reverse drift type III burst appearing almost simultaneously on the high side. The authors call the burst type III a burst pair. It is a typical characteristic of two type III bursts that they are morphologically symmetric about some frequency from 1.64 GHz to 1.78 GHz on the dynamic spectra records, which indicates that there are two different electron beams from the same acceleration region travelling simultaneously in opposite directions (upward and downward). A magnetic reconnection mode is an interpretation of type III burst pair.

  11. Fusion Power Demonstration III

    SciTech Connect

    Lee, J.D.

    1985-07-01

    This is the third in the series of reports covering the Fusion Power Demonstration (FPD) design study. This volume considers the FPD-III configuration that incorporates an octopole end plug. As compared with the quadrupole end-plugged designs of FPD-I and FPD-II, this octopole configuration reduces the number of end cell magnets and shortens the minimum ignition length of the central cell. The end-cell plasma length is also reduced, which in turn reduces the size and cost of the end cell magnets and shielding. As a contiuation in the series of documents covering the FPD, this report does not stand alone as a design description of FPD-III. Design details of FPD-III subsystems that do not differ significantly from those of the FPD-II configuration are not duplicated in this report.

  12. Summary of Session III

    SciTech Connect

    Furman, M.A.

    2002-06-19

    This is a summary of the talks presented in Session III ''Simulations of Electron-Cloud Build Up'' of the Mini-Workshop on Electron-Cloud Simulations for Proton and Positron Beams ECLOUD-02, held at CERN, 15-18 April 2002.

  13. The Apple III.

    ERIC Educational Resources Information Center

    Ditlea, Steve

    1982-01-01

    Describes and evaluates the features, performance, peripheral devices, available software, and capabilities of the Apple III microcomputer. The computer's operating system, its hardware, and the commercially produced software it accepts are discussed. Specific applications programs for financial planning, accounting, and word processing are…

  14. Pacific Barrier Radar III (PACBAR III)

    NASA Astrophysics Data System (ADS)

    Miller, C. D.; Sigler, J. D.

    1983-11-01

    The Pacific Barrier (PACBAR III) C-band radar is being installed at the Western Space and Missile Center to furnish Revolution 0 detection of foreign launches. Previously installed on a tracking ship, the upgraded system will also identify and target space objects, maintain a catalog, and cover maneuvers and decay of space objects. Nominal operation will comprise a search of a predesignated 15 deg azimuth with the capability of detecting a 6 sq m target in a 400 km orbit, track spacecraft in orbits up to 800 km altitude, have a range resolution of about 80 yd, provide realtime payload and rocket body discrimination, and transmit two-way digital message traffic between the Center and NORAD in Cheyenne Mt. Interlaced vertical and horizontal pulses will augment the search and acquisition capabilities, and the antenna will have a 140 deg plunge range. The transmitter will function at 5.4-5.65 GHz, 320 p/sec, with a peak power of 0.8 MW, and the system will have a nonambiguous range of 32,768 nmi.

  15. The Mark III VLBI System

    NASA Technical Reports Server (NTRS)

    Rogers, A. E. E.; Whitney, A. R.; Levine, J. I.; Nesman, E. F.; Webber, J. C.; Hinteregger, H. F.

    1988-01-01

    Geodetic measurements have errors in centimeter range. Collection of three reports describes both equipment and results of some measurements taken with Mark III very-long-baseline interferometry (VLBI) system. Has demonstrated high accuracy over short baselines, where phase-delay measurements used. Advanced hardware, called Mark III A, developed to improve system performance and efficiency. Original Mark III hardware and III A subsystem upgrades developed as part of NASA Crustal Dynamics Project at Haystack Observatory.

  16. Type III Hyperlipoproteinaemia

    PubMed Central

    Borrie, Peter

    1969-01-01

    Eighteen patients with type III hyperlipoproteinaemia, diagnosed on the basis of skin lesions, serum lipids, and lipoprotein electrophoresis, have been fully investigated over a period of 15 years. The incidence of coronary artery disease was only slightly increased, and was not increased at all among first-degree relatives. Peripheral occlusive arterial disease was probably more common. An increased incidence of carbohydrate intolerance was found in neither the patients nor their relatives. The effects of treatment on the skin were uniformly good. ImagesFig. 1Fig. 2 PMID:5783124

  17. High temperature triggers the metabolism of S-nitrosothiols in sunflower mediating a process of nitrosative stress which provokes the inhibition of ferredoxin-NADP reductase by tyrosine nitration.

    PubMed

    Chaki, Mounira; Valderrama, Raquel; Fernández-Ocaña, Ana M; Carreras, Alfonso; Gómez-Rodríguez, Maria V; López-Jaramillo, Javier; Begara-Morales, Juan C; Sánchez-Calvo, Beatriz; Luque, Francisco; Leterrier, Marina; Corpas, Francisco J; Barroso, Juan B

    2011-11-01

    High temperature (HT) is considered a major abiotic stress that negatively affects both vegetative and reproductive growth. Whereas the metabolism of reactive oxygen species (ROS) is well established under HT, less is known about the metabolism of reactive nitrogen species (RNS). In sunflower (Helianthus annuus L.) seedlings exposed to HT, NO content as well as S-nitrosoglutathione reductase (GSNOR) activity and expression were down-regulated with the simultaneous accumulation of total S-nitrosothiols (SNOs) including S-nitrosoglutathione (GSNO). However, the content of tyrosine nitration (NO(2) -Tyr) studied by high-performance liquid chromatography with tandem mass spectrometry (LC-MS/MS) and by confocal laser scanning microscope was induced. Nitroproteome analysis under HT showed that this stress induced the protein expression of 13 tyrosine-nitrated proteins. Among the induced proteins, ferredoxin-NADP reductase (FNR) was selected to evaluate the effect of nitration on its activity after heat stress and in vitro conditions using 3-morpholinosydnonimine (SIN-1) (peroxynitrite donor) as the nitrating agent, the FNR activity being inhibited. Taken together, these results suggest that HT augments SNOs, which appear to mediate protein tyrosine nitration, inhibiting FNR, which is involved in the photosynthesis process.

  18. POPULATION III HYPERNOVAE

    SciTech Connect

    Smidt, Joseph; Whalen, Daniel J.; Wiggins, Brandon K.; Even, Wesley; Fryer, Chris L.; Johnson, Jarrett L.

    2014-12-20

    Population III supernovae have been of growing interest of late for their potential to directly probe the properties of the first stars, particularly the most energetic events that are visible near the edge of the observable universe. Until now, hypernovae, the unusually energetic Type Ib/c supernovae that are sometimes associated with gamma-ray bursts, have been overlooked as cosmic beacons at the highest redshifts. In this, the latest of a series of studies on Population III supernovae, we present numerical simulations of 25-50 M {sub ☉} hypernovae and their light curves done with the Los Alamos RAGE and SPECTRUM codes. We find that they will be visible at z = 10-15 to the James Webb Space Telescope and z = 4-5 to the Wide-Field Infrared Survey Telescope, tracing star formation rates in the first galaxies and at the end of cosmological reionization. If, however, the hypernova crashes into a dense shell ejected by its progenitor, it is expected that a superluminous event will occur that may be seen at z ∼ 20 in the first generation of stars.

  19. Pseudo Class III malocclusion

    PubMed Central

    Al-Hummayani, Fadia M.

    2016-01-01

    The treatment of deep anterior crossbite is technically challenging due to the difficulty of placing traditional brackets with fixed appliances. This case report represents a none traditional treatment modality to treat deep anterior crossbite in an adult pseudo class III malocclusion complicated by severely retruded, supraerupted upper and lower incisors. Treatment was carried out in 2 phases. Phase I treatment was performed by removable appliance “modified Hawley appliance with inverted labial bow,” some modifications were carried out to it to suit the presented case. Positive overbite and overjet was accomplished in one month, in this phase with minimal forces exerted on the lower incisors. Whereas, phase II treatment was performed with fixed appliances (braces) to align teeth and have proper over bite and overjet and to close posterior open bite, this phase was accomplished within 11 month. PMID:27052290

  20. Pseudo Class III malocclusion.

    PubMed

    Al-Hummayani, Fadia M

    2016-04-01

    The treatment of deep anterior crossbite is technically challenging due to the difficulty of placing traditional brackets with fixed appliances. This case report represents a none traditional treatment modality to treat deep anterior crossbite in an adult pseudo class III malocclusion complicated by severely retruded, supraerupted upper and lower incisors. Treatment was carried out in 2 phases. Phase I treatment was performed by removable appliance "modified Hawley appliance with inverted labial bow," some modifications were carried out to it to suit the presented case. Positive overbite and overjet was accomplished in one month, in this phase with minimal forces exerted on the lower incisors. Whereas, phase II treatment was performed with fixed appliances (braces) to align teeth and have proper over bite and overjet and to close posterior open bite, this phase was accomplished within 11 month.

  1. Title III and Cultural Diversity.

    ERIC Educational Resources Information Center

    The Title III Quarterly, 1973

    1973-01-01

    Title III projects dealing with cultural diversity in the classroom are described in this issue of the Title III Quarterly. Major articles are devoted to the following projects: Two Arts Culture Three Project, developing the crafts and music of mountain whites, blacks, and Cherokees; the Rota Bilingual Project, the Marianas District, emphasizing…

  2. SUPERSTARS III: 6-8.

    ERIC Educational Resources Information Center

    North Carolina State Dept. of Public Education, Raleigh.

    SUPERSTARS III is a K-8 program designed as an enrichment opportunity for self-directed learners in mathematics. The basic purpose of SUPERSTARS III is to provide the extra challenge that self-motivated students need in mathematics and to do so in a structured, long-term program that does not impinge on the normal classroom routine or the…

  3. Using dBase III.

    ERIC Educational Resources Information Center

    Evans, Janet; And Others

    1986-01-01

    Four articles on dBASE III include three on library applications: a photocopy invoicing system for interlibrary loan, a vertical file subject headings list program, and a subject index to statistical resources. Another article explains the differences between interpreters and compilers and the advantages of the Clipper compiler for dBASE III. (EM)

  4. SUPERSTARS III: 3-5.

    ERIC Educational Resources Information Center

    North Carolina State Dept. of Public Education, Raleigh.

    SUPERSTARS III is a K-8 program designed as an enrichment opportunity for self-directed learners in mathematics. The basic purpose of SUPERSTARS III is to provide the extra challenge that self-motivated students need in mathematics and to do so in a structured, long-term program that does not impinge on the normal classroom routine or the…

  5. PREFACE: Quantum Optics III

    NASA Astrophysics Data System (ADS)

    Orszag, M.; Retamal, J. C.; Saavedra, C.; Wallentowitz, S.

    2007-06-01

    All the 50 years of conscious pondering did not bring me nearer to an answer to the question `what is light quanta?'. Nowadays, every rascal believes, he knows it, however, he is mistaken. (A Einstein, 1951 in a letter to M Besso) Quantum optics has played a key role in physics in the last several decades. On the other hand, in these early decades of the information age, the flow of information is becoming more and more central to our daily life. Thus, the related fields of quantum information theory as well as Bose-Einstein condensation have acquired tremendous importance in the last couple of decades. In Quantum Optics III, a fusion of these fields appears in a natural way. Quantum Optics III was held in Pucón, Chile, in 27-30 of November, 2006. This beautiful location in the south of Chile is near the lake Villarrica and below the snow covered volcano of the same name. This fantastic environment contributed to a relaxed atmosphere, suitable for informal discussion and for the students to have a chance to meet the key figures in the field. The previous Quantum Optics conferences took place in Santiago, Chile (Quantum Optics I, 2000) and Cozumel, Mexico (Quantum Optics II, 2004). About 115 participants from 19 countries attended and participated in the meeting to discuss a wide variety of topics such as quantum-information processing, experiments related to non-linear optics and squeezing, various aspects of entanglement including its sudden death, correlated twin-photon experiments, light storage, decoherence-free subspaces, Bose-Einstein condensation, discrete Wigner functions and many more. There was a strong Latin-American participation from Argentina, Brazil, Chile, Colombia, Peru, Uruguay, Venezuela and Mexico, as well as from Europe, USA, China, and Australia. New experimental and theoretical results were presented at the conference. In Latin-America a quiet revolution has taken place in the last twenty years. Several groups working in quantum optics and

  6. Viking Phase III

    NASA Technical Reports Server (NTRS)

    1978-01-01

    VIKING PHASE III - With the incredible success of the Viking missions on Mars, mission operations have progressed though a series of phases - each being funded as mission success dictated its potential. The Viking Primary Mission phase was concluded in November, 1976, when the reins were passed on to the second phase - the Viking Extended Mission. The Extended Mission successfully carried spacecraft operations through the desired period of time needed to provided a profile of a full Martian year, but would have fallen a little short of connecting and overlapping a full Martian year of Viking operations which scientists desired as a means of determining the degree of duplicity in the red planet's seasons - at least for the summer period. Without this continuation of spacecraft data acquisitions to and beyond the seasonal points when the spacecraft actually began their Mars observations, there would be no way of knowing whether the changing environmental values - such as temperatures and winds atmospheric dynamics and water vapor, surface thermal dynamics, etc. - would match up with those acquired as the spacecraft began investigations during the summer and fall of 1976. This same broad interest can be specifically pursued at the surface - where hundreds of rocks, soil drifts and other features have become extremely familiar during long-term analysis. This picture was acquired on the 690th Martian day of Lander 1 operations - 4009th picture sequence commanded of the two Viking Landers. As such, it became the first picture acquired as the third phase of Viking operations got under way - the Viking Continuation Mission. Between the start of the Continuation Mission in April, 1978, until spacecraft operations are concluded in November, the landers will acquire an additional 200 pictures. These will be used to monitor the two landscaped for the surface changes. All four cameras, two on Lander 1 and two on Lander 2, continue to operate perfectly. Both landers will also

  7. Like Father, Like Son: Assessment of the Morphological Affinities of A.L. 288–1 (A. afarensis), Sts 7 (A. africanus) and Omo 119–73–2718 (Australopithecus sp.) through a Three-Dimensional Shape Analysis of the Shoulder Joint

    PubMed Central

    Arias-Martorell, Julia; Potau, Josep Maria; Bello-Hellegouarch, Gaëlle; Pérez-Pérez, Alejandro

    2015-01-01

    The postcranial evidence for the Australopithecus genus indicates that australopiths were able bipeds; however, the morphology of the forelimbs and particularly that of the shoulder girdle suggests that they were partially adapted to an arboreal lifestyle. The nature of such arboreal adaptations is still unclear, as are the kind of arboreal behaviors in which australopiths might have engaged. In this study we analyzed the shape of the shoulder joint (proximal humerus and glenoid cavity of the scapula) of three australopith specimens: A.L. 288–1 (A. afarensis), Sts 7 (A. africanus) and Omo 119–73–2718 (Australopithecus sp.) with three-dimensional geometric morphometrics. The morphology of the specimens was compared with that of a wide array of living anthropoid taxa and some additional fossil hominins (the Homo erectus specimen KNM-WT 15000 and the H. neanderthalensis specimen Tabun 1). Our results indicate that A.L. 288–1 shows mosaic traits resembling H. sapiens and Pongo, whereas the Sts 7 shoulder is most similar to the arboreal apes and does not present affinities with H. sapiens. Omo 119–73–2718 exhibits morphological affinities with the more arboreal and partially suspensory New World monkey Lagothrix. The shoulder of the australopith specimens thus shows a combination of primitive and derived traits (humeral globularity, enhancement of internal and external rotation of the joint), related to use of the arm in overhead positions. The genus Homo specimens show overall affinities with H. sapiens at the shoulder, indicating full correspondence of these hominin shoulders with the modern human morphotype. PMID:25651542

  8. Like father, like son: assessment of the morphological affinities of A.L. 288-1 (A. afarensis), Sts 7 (A. africanus) and Omo 119-73-2718 (Australopithecus sp.) through a three-dimensional shape analysis of the shoulder joint.

    PubMed

    Arias-Martorell, Julia; Potau, Josep Maria; Bello-Hellegouarch, Gaëlle; Pérez-Pérez, Alejandro

    2015-01-01

    The postcranial evidence for the Australopithecus genus indicates that australopiths were able bipeds; however, the morphology of the forelimbs and particularly that of the shoulder girdle suggests that they were partially adapted to an arboreal lifestyle. The nature of such arboreal adaptations is still unclear, as are the kind of arboreal behaviors in which australopiths might have engaged. In this study we analyzed the shape of the shoulder joint (proximal humerus and glenoid cavity of the scapula) of three australopith specimens: A.L. 288-1 (A. afarensis), Sts 7 (A. africanus) and Omo 119-73-2718 (Australopithecus sp.) with three-dimensional geometric morphometrics. The morphology of the specimens was compared with that of a wide array of living anthropoid taxa and some additional fossil hominins (the Homo erectus specimen KNM-WT 15000 and the H. neanderthalensis specimen Tabun 1). Our results indicate that A.L. 288-1 shows mosaic traits resembling H. sapiens and Pongo, whereas the Sts 7 shoulder is most similar to the arboreal apes and does not present affinities with H. sapiens. Omo 119-73-2718 exhibits morphological affinities with the more arboreal and partially suspensory New World monkey Lagothrix. The shoulder of the australopith specimens thus shows a combination of primitive and derived traits (humeral globularity, enhancement of internal and external rotation of the joint), related to use of the arm in overhead positions. The genus Homo specimens show overall affinities with H. sapiens at the shoulder, indicating full correspondence of these hominin shoulders with the modern human morphotype.

  9. Cranial mononeuropathy III - diabetic type

    MedlinePlus

    ... diabetic type of cranial mononeuropathy III is a complication of diabetes . It causes double vision and eyelid drooping . ... Cooper ME, Vinik AI, Plutzky J, Boulton AJM. Complications of diabetes mellitus. In: Melmed S, Polonsky KS, Larsen PR, Kronenberg ...

  10. Response of Chloroplast NAD(P)H Dehydrogenase-Mediated Cyclic Electron Flow to a Shortage or Lack in Ferredoxin-Quinone Oxidoreductase-Dependent Pathway in Rice Following Short-Term Heat Stress

    PubMed Central

    Essemine, Jemaa; Qu, Mingnan; Mi, Hualing; Zhu, Xin-Guang

    2016-01-01

    Cyclic electron flow (CEF) around photosystem I (PSI) can protect photosynthetic electron carriers under conditions of stromal over-reduction. The goal of the research reported in this paper was to investigate the responses of both PSI and photosystem II (PSII) to a short-term heat stress in two rice lines with different capacities of cyclic electron transfer, i.e., Q4149 with a high capacity (hcef) and C4023 with a low capacity (lcef). The absorbance change at 820 nm (ΔA820) was used here to assess the charge separation in the PSI reaction center (P700). The results obtained show that short-term heat stress abolishes the ferredoxin-quinone oxidoreductase (FQR)-dependent CEF in rice and accelerates the initial rate of P700+ re-reduction. The P700+ amplitude was slightly increased at a moderate heat-stress (35°C) because of a partial restriction of FQR but it was decreased following high heat-stress (42°C). Assessment of PSI and PSII activities shows that PSI is more susceptible to heat stress than PSII. Under high temperature, FQR-dependent CEF was completely removed and NDH-dependent CEF was up-regulated and strengthened to a higher extent in C4023 than in Q4149. Specifically, under normal growth temperature, hcef (Q4149) was characterized by higher FQR- and chloroplast NAD(P)H dehydrogenase (NDH)-dependent CEF rates than lcef (C4023). Following thermal stress, the activation of NDH-pathway was 130 and 10% for C4023 and Q4149, respectively. Thus, the NDH-dependent CEF may constitute the second layer of plant protection and defense against heat stress after the main route, i.e., FQR-dependent CEF, reaches its capacity. We discuss the possibility that under high heat stress, the NDH pathway serves as a safety valve to dissipate excess energy by cyclic photophosphorylation and overcome the stroma over-reduction following inhibition of CO2 assimilation and any shortage or lack in the FQR pathway. The potential role of the NDH-dependent pathway during the evolution

  11. Impact analysis of Minuteman III Payload Transporter Type III

    SciTech Connect

    Stirbis, P.P.

    1993-12-01

    An analysis of the impact of the Minuteman III Payload Transporter Type III into a nonyielding target at 46 m.p.h. and 30 m.p.h., and into a yielding target at 46 m.p.h. is presented. The analysis considers the structural response of the tiedown system which secures the Minuteman III re-entry system to the floor of the payload transporter. A finite element model of the re-entry system, its tiedown system, which includes tie-rods and shear pins, and the pallet plate which is attached to the transporter floating plate, was constructed. Because accelerations of the payload transporter are not known, acceleration data from one-quarter scale testing of the Safe Secure Trailer was used to investigate the response of the tiedown system. These accelerations were applied to the pallet plate. The ABAQUS computer code was used to predict the forces in the members of the tiedown system.

  12. Dissociation of cerium(III) and neodymium(III) phthalocyanines

    NASA Astrophysics Data System (ADS)

    Lomova, T. N.

    2015-07-01

    The kinetics of dissociation of phthalocyanine complexes with cerium(III) and neodymium(III) (X)LnPc (X = Cl-, Br-, AcO-) under the action of acetic acid in ethanol with isolation of the macrocyclic ligand depending on the temperature was studied. The kinetic equations with the numerical values of rate constants, activation parameters, and the stoichiometric mechanisms with the limiting simple reaction between the nonionized AcOH molecule and (phthalocyaninato)lanthanide(III) in the axially coordinated ((X)LnPc, cerium complexes) or axially ionized ([(AcOH)LnPc]+X-, neodymium complexes) state were derived by solving the direct and inverse problems. As shown by a comparative analysis of quantitative kinetic data, the state is determined by the electronic structure of the metal cation and the mutual effect of the axial and equatorial ligands in the first coordination sphere.

  13. The START III bargaining space

    SciTech Connect

    Karas, T.H.

    1998-08-01

    The declining state of the Russian military and precarious Russian economic condition will give the US considerable advantages at the START III bargaining table. Taking the US-RF asymmetries into account, this paper discusses a menu of START III measures the US could ask for, and measures it could offer in return, in attempting to negotiate an equitable treaty. Measures the US might seek in a START III treaty include: further reductions in deployed strategic nuclear warheads, irreversibility of reductions through warhead dismantlement; beginning to bring theater nuclear weapons under mutual control, and increased transparency into the Russian nuclear weapons complex. The US may, however, wish to apply its bargaining advantages to attempting to achieve the first steps toward two long-range goals that would enhance US security: bringing theater nuclear weapons into the US-RF arms control arena, and increasing transparency into the Russian nuclear weapons complex. In exchange for measures relating to these objectives, the US might consider offering to Russia: Further strategic weapons reductions approaching levels at which the Russians believe they could maintain a degree of parity with the US; Measures to decrease the large disparities in potential deliver-system uploading capabilities that appear likely under current START II/START III scenarios; and Financial assistance in achieving START II/START III reductions as rapidly as is technically possible.

  14. Thermal and optical properties of Tb(III), Eu(III) and Tb(III)/Eu(III) co-complexed silicone fluorinated acrylate copolymer

    NASA Astrophysics Data System (ADS)

    Zhai, Yinfeng; Xie, Hongde; Cai, Haijun; Cai, Peiqing; Seo, Hyo Jin

    2015-07-01

    Tb(III), Eu(III) and Tb(III)/Eu(III) activated silicone fluorinated acrylate (SFA) have been successfully synthesized using the method of semi-continuous emulsion polymerization. The copolymers are characterized by flourier transform infrared (FT-IR), thermal gravity analysis (TGA), photoluminescence excitation (PLE) and emission (PL) spectroscopy. The copolymer containing Tb(III) and Eu(III) ions display green and red luminescent colors under UV light excitation, respectively. The TGA curves show the thermal decomposition temperatures of the copolymers are up to about 300 °C. The PL spectra show a strong green emission at 546 nm (5D4 → 7F5) of Tb(III) complexed copolymers, and show a prominent red emission at 615 nm (5D0 → 7F2) of Eu(III) complexed copolymers. Different concentrations of Eu(III) and Tb(III) ions are introduced into the copolymer and the energy transfer from Tb(III) to Eu(III) ions in the copolymer was found. Thus, based on the results it can be suggested that SFA:Eu(III), SFA:Tb(III) and SFA:Tb(III)/Eu(III) can be used potentially as luminescent materials.

  15. III-Nitride nanowire optoelectronics

    NASA Astrophysics Data System (ADS)

    Zhao, Songrui; Nguyen, Hieu P. T.; Kibria, Md. G.; Mi, Zetian

    2015-11-01

    Group-III nitride nanowire structures, including GaN, InN, AlN and their alloys, have been intensively studied in the past decade. Unique to this material system is that its energy bandgap can be tuned from the deep ultraviolet (~6.2 eV for AlN) to the near infrared (~0.65 eV for InN). In this article, we provide an overview on the recent progress made in III-nitride nanowire optoelectronic devices, including light emitting diodes, lasers, photodetectors, single photon sources, intraband devices, solar cells, and artificial photosynthesis. The present challenges and future prospects of III-nitride nanowire optoelectronic devices are also discussed.

  16. First Stars III Conference Summary

    NASA Astrophysics Data System (ADS)

    O'Shea, B. W.; McKee, C. F.; Heger, A.; Abel, T.

    2008-03-01

    The understanding of the formation, life, and death of Population III stars, as well as the impact that these objects had on later generations of structure formation, is one of the foremost issues in modern cosmological research and has been an active area of research during the past several years. We summarize the results presented at "First Stars III," a conference sponsored by Los Alamos National Laboratory, the Kavli Institute for Particle Astrophysics and Cosmology, and the Joint Institute for Nuclear Astrophysics. This conference, the third in a series, took place in July 2007 at the La Fonda Hotel in Santa Fe, New Mexico, U.S.A.

  17. Organometallic neptunium(III) complexes.

    PubMed

    Dutkiewicz, Michał S; Farnaby, Joy H; Apostolidis, Christos; Colineau, Eric; Walter, Olaf; Magnani, Nicola; Gardiner, Michael G; Love, Jason B; Kaltsoyannis, Nikolas; Caciuffo, Roberto; Arnold, Polly L

    2016-08-01

    Studies of transuranic organometallic complexes provide a particularly valuable insight into covalent contributions to the metal-ligand bonding, in which the subtle differences between the transuranium actinide ions and their lighter lanthanide counterparts are of fundamental importance for the effective remediation of nuclear waste. Unlike the organometallic chemistry of uranium, which has focused strongly on U(III) and has seen some spectacular advances, that of the transuranics is significantly technically more challenging and has remained dormant. In the case of neptunium, it is limited mainly to Np(IV). Here we report the synthesis of three new Np(III) organometallic compounds and the characterization of their molecular and electronic structures. These studies suggest that Np(III) complexes could act as single-molecule magnets, and that the lower oxidation state of Np(II) is chemically accessible. In comparison with lanthanide analogues, significant d- and f-electron contributions to key Np(III) orbitals are observed, which shows that fundamental neptunium organometallic chemistry can provide new insights into the behaviour of f-elements.

  18. Title III hazardous air pollutants

    SciTech Connect

    Todd, R.

    1995-12-31

    The author presents an overview of the key provisions of Title III of the Clean Air Act Amendments of 1990. The key provisions include the following: 112(b) -- 189 Hazardous Air Pollutants (HAP); 112(a) -- Major Source: 10 TPY/25 TPY; 112(d) -- Application of MACT; 112(g) -- Modifications; 112(I) -- State Program; 112(j) -- The Hammer; and 112(r) -- Accidental Release Provisions.

  19. Jovian type III radio bursts

    NASA Technical Reports Server (NTRS)

    Kurth, W. S.; Gurnett, D. A.; Scarf, F. L.

    1989-01-01

    Radio bursts have been observed in the Voyager plasma wave data from Jupiter that bear a striking resemblance to solar type III radio bursts. The emissions lie in the frequency range near 10 kHz, have durations of a minute or so, and occur in a set of periodically spaced bursts. The spacing between primary bursts is typically 15 min, but the bursts may have additional components which recur on time scales of about 3 min. The similarity with solar type III radio bursts suggests a source mechanism involving the movement of energetic electrons through a density gradient in the plasma surrounding Jupiter. The periodicity of bursts suggests Io may be involved in the generation of waves, since the timing is similar to the Alfven wave travel time from one hemisphere to the other through the Io torus.

  20. Transition probabilities in O III

    NASA Astrophysics Data System (ADS)

    Froese Fischer, Charlotte

    1994-01-01

    Transition data has been computed in the MCHF + Breit-Pauli approximation for a number of the low lying triplets in O III. Special attention was given to the 2p3p 3P-2p3d 3P transition which is a primary cascade for the Bowen fluorescence mechanism in O III. The relativistic, largely spin-orbit, effect on the intensity ratio of primary decays was found to be as large as 50%, whereas the effect on secondary cascades was less than 30%. Agreement with astrophysically observed intensity ratios is excellent. There also is good agreement between the present liftimes and the beam-foil mean lifetimes obtained by Pinnington et al., though for 2p3p 3D and 3S the theoretical lifetimes are considerably shorter.

  1. NIF Title III engineering plan

    SciTech Connect

    Deis, G

    1998-06-01

    The purpose of this document is to define the work that must be accomplished by the NIF Project during Title III Engineering. This definition is intended to be sufficiently detailed to provide a framework for yearly planning, to clearly identify the specific deliverables so that the Project teams can focus on them, and to provide a common set of objectives and processes across the Project. This plan has been preceded by similar documents for Title I and Title II design and complements the Site Management Plan, the Project Control Manual, the Quality Assurance Program Plan, the RM Parsons NIF Title III Configuration Control Plan, the Integrated Project Schedule, the Preliminary Safety Analysis Report, the Configuration Management Plan, and the Transition Plan.

  2. Silver europium(III) polyphosphate

    PubMed Central

    Ayadi, Mounir; Férid, Mokhtar; Moine, Bernard

    2009-01-01

    Europium(III) silver polyphosphate, AgEu(PO3)4, was prepared by the flux method. The atomic arrangement is built up by infinite (PO3)n chains (periodicity of 4) extending along the c axis. These chains are joined to each other by EuO8 dodeca­hedra. The Ag+ cations are located in the voids of this arrangement and are surrounded by five oxygen atoms in a distorted [4+1] coordination. PMID:21582031

  3. Organometallic neptunium(III) complexes

    NASA Astrophysics Data System (ADS)

    Dutkiewicz, Michał S.; Farnaby, Joy H.; Apostolidis, Christos; Colineau, Eric; Walter, Olaf; Magnani, Nicola; Gardiner, Michael G.; Love, Jason B.; Kaltsoyannis, Nikolas; Caciuffo, Roberto; Arnold, Polly L.

    2016-08-01

    Studies of transuranic organometallic complexes provide a particularly valuable insight into covalent contributions to the metal-ligand bonding, in which the subtle differences between the transuranium actinide ions and their lighter lanthanide counterparts are of fundamental importance for the effective remediation of nuclear waste. Unlike the organometallic chemistry of uranium, which has focused strongly on UIII and has seen some spectacular advances, that of the transuranics is significantly technically more challenging and has remained dormant. In the case of neptunium, it is limited mainly to NpIV. Here we report the synthesis of three new NpIII organometallic compounds and the characterization of their molecular and electronic structures. These studies suggest that NpIII complexes could act as single-molecule magnets, and that the lower oxidation state of NpII is chemically accessible. In comparison with lanthanide analogues, significant d- and f-electron contributions to key NpIII orbitals are observed, which shows that fundamental neptunium organometallic chemistry can provide new insights into the behaviour of f-elements.

  4. Association of europium(III), americium(III), and curium(III) with cellulose, chitin, and chitosan.

    PubMed

    Ozaki, Takuo; Kimura, Takaumi; Ohnuki, Toshihiko; Kirishima, Akira; Yoshida, Takahiro; Isobe, Hiroshi; Francis, Arokiasamy J

    2006-08-01

    The association of trivalent f-elements-Eu(III), Am(III), and Cm(III)--with cellulose, chitin, and chitosan was determined by batch experiments and time-resolved, laser-induced fluorescence spectroscopy (TRLFS). The properties of these biopolymers as an adsorbent were characterized based on speciation calculation of Eu(III). The adsorption study showed that an increase of the ionic strength by NaCl did not affect the adsorption kinetics of Eu(III), Am(III), and Cm(III) for all the biopolymers, but the addition of Na2CO3 significantly delayed the kinetics because of their trivalent f-element complexation with carbonate ions. It also was suggested from the speciation calculation study that all the biopolymers were degraded under alkaline conditions, leading to their masking of the adsorption of Eu(III), Am(III), and Cm(III) on the nondegraded biopolymers. The masking effect was higher for cellulose than for chitin and chitosan, indicating that of the three, cellulose was degraded most significantly in alkaline solutions. Desorption experiments suggested that some portion of the adsorbed Eu(III) penetrated deep into the matrix, being isolated in a cavity-like site. The TRLFS study showed that the coordination environment of Eu(III) is stabilized mainly by the inner spherical coordination in chitin and by the outer spherical coordination in chitosan, with less association in cellulose in comparison to chitin and chitosan. These results suggest that the association of these biopolymers with Eu(III), Am(III), and Cm(III) is governed not only by the affinity of the functional groups alone but also by other factors, such as the macromolecular steric effect. The association of degraded materials of the biopolymers also should be taken into consideration for an accurate prediction of the influence of biopolymers on the migration behavior of trivalent f-elements.

  5. 21 CFR 1308.13 - Schedule III.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 9 2012-04-01 2012-04-01 false Schedule III. 1308.13 Section 1308.13 Food and Drugs DRUG ENFORCEMENT ADMINISTRATION, DEPARTMENT OF JUSTICE SCHEDULES OF CONTROLLED SUBSTANCES Schedules § 1308.13 Schedule III. (a) Schedule III shall consist of the drugs and other substances,...

  6. 21 CFR 1308.13 - Schedule III.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 9 2010-04-01 2010-04-01 false Schedule III. 1308.13 Section 1308.13 Food and Drugs DRUG ENFORCEMENT ADMINISTRATION, DEPARTMENT OF JUSTICE SCHEDULES OF CONTROLLED SUBSTANCES Schedules § 1308.13 Schedule III. (a) Schedule III shall consist of the drugs and other substances,...

  7. Development of Demographic Norms for Four New WAIS-III/WMS-III Indexes

    ERIC Educational Resources Information Center

    Lange, Rael T.; Chelune, Gordon J.; Taylor, Michael J.; Woodward, Todd S.; Heaton, Robert K.

    2006-01-01

    Following the publication of the third edition Wechsler scales (i.e., WAIS-III and WMS-III), demographically corrected norms were made available in the form of a computerized scoring program (i.e., WAIS-III/WMS-III/WIAT-II Scoring Assistant). These norms correct for age, gender, ethnicity, and education. Since then, four new indexes have been…

  8. Palladium(III) in Synthesis and Catalysis

    PubMed Central

    Powers, David C.; Ritter, Tobias

    2011-01-01

    While the organometallic chemistry of Pd in its (0), (+II), and (+IV) oxidation states is well-established, organometallic Pd(III) chemistry remains widely unexplored. Few characterized Pd(III) complexes are known, which has inhibited detailed study of the organometallic chemistry of Pd(III). In this review, the potential roles of both mono- and dinuclear Pd(III) complexes in organometallic chemistry will be discussed. While not widely recognized, Pd in the (+III) oxidation state may play a significant role in a variety of known Pd-catalyzed reactions. PMID:21461129

  9. Development of demographic norms for four new WAIS-III/WMS-III indexes.

    PubMed

    Lange, Rael T; Chelune, Gordon J; Taylor, Michael J; Woodward, Todd S; Heaton, Robert K

    2006-06-01

    Following the publication of the third edition Wechsler scales (i.e., WAIS-III and WMS-III), demographically corrected norms were made available in the form of a computerized scoring program (i.e., WAIS-III/WMS-III/WIAT-II Scoring Assistant). These norms correct for age, gender, ethnicity, and education. Since then, four new indexes have been developed: the WAIS-III General Ability Index, the WMS-III Delayed Memory Index, and the two alternate Immediate and Delayed Memory Indexes. The purpose of this study was to develop demographically corrected norms for the four new indexes using the standardization sample and education oversample from the WAIS-III and WMS-III. These norms were developed using the same methodology as the demographically corrected norms made available in the WAIS-III/WMS-III/WIAT-II Scoring Assistant.

  10. The Nimbus III Michelson Interferometer.

    PubMed

    Hanel, R A; Schlachman, B; Clark, F D; Prokesh, C H; Taylor, J B; Wilson, W M; Chaney, L

    1970-08-01

    The Michelson interferometer flown on Nimbus III in April 1969 has obtained infrared emission spectra of the earth and its atmosphere within 400 cm(-1) and 2000 cm(-1) (5 micro and 25 micro). Spectra of good quality have been recorded with a spectral resolution corresponding to 5 cm(-1). This paper discusses the design of the instrument including the optical layout, the phase locked loop operation of the Michelson motor, and the functioning of the reference interferometer. The methods of data reduction and in-flight calibration are demonstrated on sample spectra recorded while in orbit around the earth.

  11. Great Warriors: Hannibal Barca and Publius Cornelius Scipio Africanus

    DTIC Science & Technology

    1984-04-01

    4;rrovides’ the student of military history--the basis for comparing the importance of strategy and tactics~ * DD IAN31473 EDITION OF INOV 65 15...Although Hannibal returned to his camp that night, he decided to move, according to Livy because of food shortages and pending desertion by the...with the exception of his campaign to Sicily and 74 Africa, Scipio was provided citizen conscripts and large supplies of food and arms to field his

  12. III-Nitride Nanowire Lasers

    SciTech Connect

    Wright, Jeremy Benjamin

    2014-07-01

    In recent years there has been a tremendous interest in nanoscale optoelectronic devices. Among these devices are semiconductor nanowires whose diameters range from 10-100 nm. To date, nanowires have been grown using many semiconducting material systems and have been utilized as light emitting diodes, photodetectors, and solar cells. Nanowires possess a relatively large index contrast relative to their dielectric environment and can be used as lasers. A key gure of merit that allows for nanowire lasing is the relatively high optical con nement factor. In this work, I discuss the optical characterization of 3 types of III-nitride nanowire laser devices. Two devices were designed to reduce the number of lasing modes to achieve singlemode operation. The third device implements low-group velocity mode lasing with a photonic crystal constructed of an array of nanowires. Single-mode operation is necessary in any application where high beam quality and single frequency operation is required. III-Nitride nanowire lasers typically operate in a combined multi-longitudinal and multi-transverse mode state. Two schemes are introduced here for controlling the optical modes and achieving single-mode op eration. The rst method involves reducing the diameter of individual nanowires to the cut-o condition, where only one optical mode propagates in the wire. The second method employs distributed feedback (DFB) to achieve single-mode lasing by placing individual GaN nanowires onto substrates with etched gratings. The nanowire-grating substrate acted as a distributed feedback mirror producing single mode operation at 370 nm with a mode suppression ratio (MSR) of 17 dB. The usage of lasers for solid state lighting has the potential to further reduce U.S. lighting energy usage through an increase in emitter e ciency. Advances in nanowire fabrication, speci cally a two-step top-down approach, have allowed for the demonstration of a multi-color array of lasers on a single chip that emit

  13. III-nitride nanowire lasers

    NASA Astrophysics Data System (ADS)

    Wright, Jeremy Benjamin

    In recent years there has been a tremendous interest in nanoscale optoelectronic devices. Among these devices are semiconductor nanowires whose diameters range from 10-100 nm. To date, nanowires have been grown using many semiconducting material systems and have been utilized as light emitting diodes, photodetectors, and solar cells. Nanowires possess a relatively large index contrast relative to their dielectric environment and can be used as lasers. A key figure of merit that allows for nanowire lasing is the relatively high optical confinement factor. In this work, I discuss the optical characterization of 3 types of III-nitride nanowire laser devices. Two devices were designed to reduce the number of lasing modes to achieve single-mode operation. The third device implements low-group velocity mode lasing with a photonic crystal constructed of an array of nanowires. Single-mode operation is necessary in any application where high beam quality and single frequency operation is required. III-Nitride nanowire lasers typically operate in a combined multi-longitudinal and multi-transverse mode state. Two schemes are introduced here for controlling the optical modes and achieving single-mode operation. The first method involves reducing the diameter of individual nanowires to the cut-off condition, where only one optical mode propagates in the wire. The second method employs distributed feedback (DFB) to achieve single-mode lasing by placing individual GaN nanowires onto substrates with etched gratings. The nanowire-grating substrate acted as a distributed feedback mirror producing single mode operation at 370 nm with a mode suppression ratio (MSR) of 17 dB. The usage of lasers for solid state lighting has the potential to further reduce U.S. lighting energy usage through an increase in emitter efficiency. Advances in nanowire fabrication, specifically a two-step top-down approach, have allowed for the demonstration of a multi-color array of lasers on a single chip

  14. DOE/NNSA perspective safeguard by design: GEN III/III+ light water reactors and beyond

    SciTech Connect

    Pan, Paul Y

    2010-12-10

    An overview of key issues relevant to safeguards by design (SBD) for GEN III/IV nuclear reactors is provided. Lessons learned from construction of typical GEN III+ water reactors with respect to SBD are highlighted. Details of SBD for safeguards guidance development for GEN III/III+ light water reactors are developed and reported. This paper also identifies technical challenges to extend SBD including proliferation resistance methodologies to other GEN III/III+ reactors (except HWRs) and GEN IV reactors because of their immaturity in designs.

  15. Decameter Type III-Like Bursts

    NASA Astrophysics Data System (ADS)

    Melnik, V. N.; Konovalenko, A. A.; Rutkevych, B. P.; Rucker, H. O.; Dorovskyy, V. V.; Abranin, E. P.; Lecacheux, A.; Brazhenko, A. I.; Stanislavskyy, A. A.

    2007-12-01

    Starting from 1960s Type III-like bursts (Type III bursts with high drift rates) in a wide frequency range from 300 to 950MHz have been observed. These new bursts observed at certain frequency being compared to the usual Type III bursts at the same frequency show similar behaviour but feature frequency drift 2-6 times higher than the normal bursts. In this paper we report the first observations of Type III-like bursts in decameter range, carried out during summer campaigns 2002 - 2004 at UTR-2 radio telescope. The circular polarization of the bursts was measured by the radio telescope URAN-2 in 2004. The observed bursts are analyzed and compared with usual Type III bursts in the decameter range. From the analysis of over 1100 Type III-like bursts, their main parameters have been found. Characteristic feature of the observed bursts is similar to Type III-like bursts at other frequencies, i.e. measured drift rates (5-10 MHz/s) of this bursts are few times larger than that for usual Type III bursts, and their durations (1-2 s) are few times smaller than that for usual Type III bursts in this frequency band.

  16. Characterization of ribonuclease III from Brucella.

    PubMed

    Wu, Chang-Xian; Xu, Xian-Jin; Zheng, Ke; Liu, Fang; Yang, Xu-Dong; Chen, Chuang-Fu; Chen, Huan-Chun; Liu, Zheng-Fei

    2016-04-01

    Bacterial ribonuclease III (RNase III) is a highly conserved endonuclease, which plays pivotal roles in RNA maturation and decay pathways by cleaving double-stranded structure of RNAs. Here we cloned rncS gene from the genomic DNA of Brucella melitensis, and analyzed the cleavage properties of RNase III from Brucella. We identified Brucella-encoding small RNA (sRNA) by high-throughput sequencing and northern blot, and found that sRNA of Brucella and Homo miRNA precursor (pre-miRNA) can be bound and cleaved by B.melitensis ribonuclease III (Bm-RNase III). Cleavage activity of Bm-RNase III is bivalent metal cations- and alkaline buffer-dependent. We constructed several point mutations in Bm-RNase III, whose cleavage activity indicated that the 133th Glutamic acid residue was required for catalytic activity. Western blot revealed that Bm-RNase III was differently expressed in Brucella virulence strain 027 and vaccine strain M5-90. Collectively, our data suggest that Brucella RNase III can efficiently bind and cleave stem-loop structure of small RNA, and might participate in regulation of virulence in Brucella.

  17. Genotypic variation in sulfur assimilation and metabolism of onion (Allium cepa L.) III. Characterization of sulfite reductase

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Genomic and cDNA sequences corresponding to a ferredoxin-sulfite reductase (SiR) have been cloned from bulb onion (Allium cepa L.) and the expression of the gene and activity of the enzyme characterised with respect to sulfur (S) supply. Cloning, mapping and expression studies revealed that onion ha...

  18. Comparative adsorption of Eu(III) and Am(III) on TPD.

    PubMed

    Fan, Q H; Zhao, X L; Ma, X X; Yang, Y B; Wu, W S; Zheng, G D; Wang, D L

    2015-09-01

    Comparative adsorption behaviors of Eu(III) and Am(III) on thorium phosphate diphosphate (TPD), i.e., Th4(PO4)4P2O7, have been studied using a batch approach and surface complexation model (SCM) in this study. The results showed that Eu(III) and Am(III) adsorption increased to a large extent with the increase in TPD dose. Strong pH-dependence was observed in both Eu(III) and Am(III) adsorption processes, suggesting that inner-sphere complexes (ISCs) were possibly responsible for the adsorption of Eu(III) and Am(III). Meanwhile, the adsorption of Eu(III) and Am(III) decreased to a different extent with the increase in ion strength, which was possibly related to outer-sphere complexes and/or ion exchange. In the presence of fulvic acid (FA), the adsorption of Eu(III) and Am(III) showed high enhancement mainly due to the ternary surface complexes of TPD-FA-Eu(3+) and TPD-FA-Am(3+). The SCM showed that one ion exchange (≡S3Am/Eu) and two ISCs (≡(XO)2Am/EuNO3 and ≡(YO)2Am/EuNO3) seemed more reasonable to quantitatively describe the adsorption edges of both Eu(III) and Am(III). Our findings obviously showed that Eu(III) could be a good analogue to study actinide behaviors in practical terms. However, it should be kept in mind that there are still obvious differences between the characteristics of Eu(III) and Am(III) in some special cases, for instance, the complex ability with organic matter and adsorption affinity to a solid surface.

  19. Mechanisms of Sb(III) Photooxidation by the Excitation of Organic Fe(III) Complexes.

    PubMed

    Kong, Linghao; He, Mengchang

    2016-07-05

    Organic Fe(III) complexes are widely distributed in the aqueous environment, which can efficiently generate free radicals under light illumination, playing a significant role in heavy metal speciation. However, the potential importance of the photooxidation of Sb(III) by organic Fe(III) complexes remains unclear. Therefore, the photooxidation mechanisms of Sb(III) were comprehensively investigated in Fe(III)-oxalate, Fe(III)-citrate and Fe(III)-fulvic acid (FA) solutions by kinetic measurements and modeling. Rapid photooxidation of Sb(III) was observed in an Fe(III)-oxalate solution over the pH range of 3 to 7. The addition of tert-butyl alcohol (TBA) as an ·OH scavenger quenched the Sb(III) oxidation, suggesting that ·OH is an important oxidant for Sb(III). However, the incomplete quenching of Sb(III) oxidation indicated the existence of other oxidants, presumably an Fe(IV) species in irradiated Fe(III)-oxalate solution. In acidic solutions, ·OH may be formed by the reaction of Fe(II)(C2O4) with H2O2, but a hypothetical Fe(IV) species may be generated by the reaction of Fe(II)(C2O4)2(2-) with H2O2 at higher pH. Kinetic modeling provides a quantitative explanation of the results. Evidence for the existence of ·OH and hypothetical Fe(IV) was also observed in an irradiated Fe(III)-citrate and Fe(III)-FA system. This study demonstrated an important pathway of Sb(III) oxidation in surface waters.

  20. National Coastal Condition Report III (2008)

    EPA Pesticide Factsheets

    The National Coastal Condition Report III (NCCR III) is the third in a series of environmental assessments of U.S. coastal waters and the Great Lakes. The report includes assessments of the nation’s estuaries in the contiguous 48 states and Puerto Rico.

  1. Synthesis, spectroscopic and antimicrobial studies of La(III), Ce(III), Sm(III) and Y(III) Metformin HCl chelates.

    PubMed

    Refat, Moamen S; Al-Azab, Fathi M; Al-Maydama, Hussein M A; Amin, Ragab R; Jamil, Yasmin M S; Kobeasy, Mohamed I

    2015-05-05

    Metal complexes of Metformin hydrochloride were prepared using La(III), Ce(III), Sm(III) and Y(III). The resulting complexes were discussed and synthesized to serve as potential insulin-mimetic. Some physical properties and analytical data of the four complexes were checked. The elemental analysis shows that La(III), Ce(III) Sm(III) and Y(III) formed complexes with Metformin in 1:3 (metal:MF) molar ratio. All the synthesized complexes are white and possess high melting points. These complexes are soluble in dimethylsulfoxide and dimethylformamide, partially soluble in hot methanol and insoluble in water and some other organic solvents. From the spectroscopic (infrared, UV-vis and florescence), effective magnetic moment and elemental analyses data, the formula structures are suggested. The results obtained suggested that Metformin reacted with metal ions as a bidentate ligand through its two imino groups. The molar conductance measurements proved that the Metformin complexes are slightly electrolytic in nature. The kinetic thermodynamic parameters such as: E(∗), ΔH(∗), ΔS(∗) and ΔG(∗) were estimated from the DTG curves. The antibacterial evaluations of the Metformin and their complexes were also performed against some gram positive, negative bacteria as well as fungi.

  2. JumpStart III Final Report.

    ERIC Educational Resources Information Center

    Cohen, Arthur M.; Brawer, Florence B.; Kozeracki, Carol A.

    This final report for the JumpStart III program presents a summary of the entrepreneurship training programs developed by each of the four JumpStart III partners selected in March 1997. Grants for the colleges totaled $354,546 over 2 years. The Jumpstart funding has been only a starting point for these and the other 12 Jumpstart partners in…

  3. Grant Administration Manual for Title III Coordinators.

    ERIC Educational Resources Information Center

    Mathis, Emily Duncan; Ashmore, Frances W.

    Guidelines for coordinators of programs under Title III of the Higher Education Act of 1965 are presented, based on a national survey of Title III program coordinators. The responsibilities of the coordinator and information on administering the Strengthening Developing Institutions Program (SDIP) grant are covered. The program can either be a…

  4. Preparation of III-V semiconductor nanocrystals

    DOEpatents

    Alivisatos, A. Paul; Olshavsky, Michael A.

    1996-01-01

    Nanometer-scale crystals of III-V semiconductors are disclosed, They are prepared by reacting a group III metal source with a group V anion source in a liquid phase at elevated temperature in the presence of a crystallite growth terminator such as pyridine or quinoline.

  5. Cyanoacrylate glue for type iii lad perforation.

    PubMed

    Trehan, V K; Nigam, Arima

    2008-01-01

    Coronary artery perforation especially type III is a rare and catastrophic complication of percutaneous coronary intervention. It mandates emergency open heart surgery if hemostasis is not achieved promptly. We report a case of type III left anterior descending artery (LAD) perforation which was managed successfully with cyanoacrylate glue.

  6. Genes, genetics, and Class III malocclusion.

    PubMed

    Xue, F; Wong, R W K; Rabie, A B M

    2010-05-01

    To present current views that are pertinent to the investigation of the genetic etiology of Class III malocclusion. Class III malocclusion is thought to be a polygenic disorder that results from an interaction between susceptibility genes and environmental factors. However, research on family pedigrees has indicated that Class III malocclusion might also be a monogenic dominant phenotype. Recent studies have reported that genes that encode specific growth factors or other signaling molecules are involved in condylar growth under mechanical strain. These genes, which include Indian hedgehog homolog (IHH), parathyroid-hormone like hormone (PTHLH), insulin-like growth factor-1 (IGF-1), and vascular endothelial growth factor (VEGF), and variations in their levels of expression play an important role in the etiology of Class III malocclusion. In addition, genome-wide scans have revealed chromosomal loci that are associated with Class III malocclusion. It is likely that chromosomal loci 1p36, 12q23, and 12q13 harbor genes that confer susceptibility to Class III malocclusion. In a case-control association study, we identified erythrocyte membrane protein band 4.1 (EPB41) to be a new positional candidate gene that might be involved in susceptibility to mandibular prognathism. Most of the earlier studies on the genetic etiology of Class III malocclusion have focused on the patterns of inheritance of this phenotype. Recent investigations have focused on understanding the genetic variables that affect Class III malocclusion and might provide new approaches to uncovering the genetic etiology of this phenotype.

  7. Preparation of III-V semiconductor nanocrystals

    DOEpatents

    Alivisatos, A.P.; Olshavsky, M.A.

    1996-04-09

    Nanometer-scale crystals of III-V semiconductors are disclosed. They are prepared by reacting a group III metal source with a group V anion source in a liquid phase at elevated temperature in the presence of a crystallite growth terminator such as pyridine or quinoline. 4 figs.

  8. Synthesis and in vitro microbial evaluation of La(III), Ce(III), Sm(III) and Y(III) metal complexes of vitamin B6 drug

    NASA Astrophysics Data System (ADS)

    Refat, Moamen S.; Al-Azab, Fathi M.; Al-Maydama, Hussein M. A.; Amin, Ragab R.; Jamil, Yasmin M. S.

    2014-06-01

    Metal complexes of pyridoxine mono hydrochloride (vitamin B6) are prepared using La(III), Ce(III), Sm(III) and Y(III). The resulting complexes are investigated. Some physical properties, conductivity, analytical data and the composition of the four pyridoxine complexes are discussed. The elemental analysis shows that the formed complexes of La(III), Ce(III), Sm(III) and Y(III) with pyridoxine are of 1:2 (metal:PN) molar ratio. All the synthesized complexes are brown in color and possess high melting points. These complexes are partially soluble in hot methanol, dimethylsulfoxide and dimethylformamide and insoluble in water and some other organic solvents. Elemental analysis data, spectroscopic (IR, UV-vis. and florescence), effective magnetic moment in Bohr magnetons and the proton NMR suggest the structures. However, definite particle size is determined by invoking the X-ray powder diffraction and scanning electron microscopy data. The results obtained suggested that pyridoxine reacted with metal ions as a bidentate ligand through its phenolate oxygen and the oxygen of the adjacent group at the 4‧-position. The molar conductance measurements proved that the pyridoxine complexes are electrolytic in nature. The kinetic and thermodynamic parameters such as: Ea, ΔH*, ΔS* and ΔG* were estimated from the DTG curves. The antibacterial evaluation of the pyridoxine and their complexes were also performed against some gram positive, negative bacteria as well as fungi.

  9. Synthesis, spectroscopic and antimicrobial studies of La(III), Ce(III), Sm(III) and Y(III) Metformin HCl chelates

    NASA Astrophysics Data System (ADS)

    Refat, Moamen S.; Al-Azab, Fathi M.; Al-Maydama, Hussein M. A.; Amin, Ragab R.; Jamil, Yasmin M. S.; Kobeasy, Mohamed I.

    2015-05-01

    Metal complexes of Metformin hydrochloride were prepared using La(III), Ce(III), Sm(III) and Y(III). The resulting complexes were discussed and synthesized to serve as potential insulin-mimetic. Some physical properties and analytical data of the four complexes were checked. The elemental analysis shows that La(III), Ce(III) Sm(III) and Y(III) formed complexes with Metformin in 1:3 (metal:MF) molar ratio. All the synthesized complexes are white and possess high melting points. These complexes are soluble in dimethylsulfoxide and dimethylformamide, partially soluble in hot methanol and insoluble in water and some other organic solvents. From the spectroscopic (infrared, UV-vis and florescence), effective magnetic moment and elemental analyses data, the formula structures are suggested. The results obtained suggested that Metformin reacted with metal ions as a bidentate ligand through its two imino groups. The molar conductance measurements proved that the Metformin complexes are slightly electrolytic in nature. The kinetic thermodynamic parameters such as: E∗, ΔH∗, ΔS∗ and ΔG∗ were estimated from the DTG curves. The antibacterial evaluations of the Metformin and their complexes were also performed against some gram positive, negative bacteria as well as fungi.

  10. Genetics Home Reference: mucolipidosis III gamma

    MedlinePlus

    ... time. People with mucolipidosis III gamma often have heart valve abnormalities and mild clouding of the clear covering ... III Gamma MedlinePlus Encyclopedia: Cloudy Cornea MedlinePlus Encyclopedia: Heart Valves General Information from MedlinePlus (5 links) Diagnostic Tests ...

  11. Cyanido Antimonate(III) and Bismuthate(III) Anions.

    PubMed

    Arlt, Sören; Harloff, Jörg; Schulz, Axel; Stoffers, Alrik; Villinger, Alexander

    2016-12-05

    The reaction of in situ generated E(CN)3 (E = Sb, Bi) with different amounts of [Ph4P]CN and [PPN]CN ([PPN](+) = [Ph3P-N-PPh3](+)) was studied, affording salts bearing the novel ions [E(CN)5](2-), [Bi2(CN)11](5-), and [Bi(CN)6](3-). The valence lone pair of electrons on the central atom of antimony and bismuth(III) compounds can be either sterically active in an unsymmetric fashion (three shorter bonds + x longer bonds) or symmetric (with rather long averaged bonds). In the presence of weakly coordinating cations (e.g., [Ph4P](+) and [PPN](+)), the solid-state structures of salts with [E(CN)5](2-) anions contain well-separated cations and monomeric anions, which display a sterically active lone pair and a monomeric square-based pyramidal (pseudo-octahedral) structure. The [Bi(CN)5·MeCN](2-) acetonitrile adduct ion exhibits a strongly distorted octahedral structure, which is better understood as a [5 + 1] coordination. The intriguing [Ph4P]6[Bi2(CN)11]CN salt consists of separated cations and anions as well as well-separated [Bi2(CN)11](5-) and CN(-) ions. The structure of the molecular [Bi2(CN)11](5-) ion can be described as two square-based-pyramidal [Bi(CN)5](2-) fragments connected by a disordered bridging CN(-) ion, thereby leading to a distorted-octahedral environment around the two Bi centers. Here the steric effect of the lone pair is much less pronounced but still present.

  12. Design III with Marker Loci

    PubMed Central

    Cockerham, C. C.; Zeng, Z. B.

    1996-01-01

    Design III is an experimental design originally proposed by R. E. COMSTOCK and H. F. ROBINSON for estimating genetic variances and the average degree of dominance for quantitative trait loci (QTL) and has recently been extended for mapping QTL. In this paper, we first extend COMSTOCK and ROBINSON's analysis of variance to include linkage, two-locus epistasis and the use of F(3) parents. Then we develop the theory and statistical analysis of orthogonal contrasts and contrast X environment interaction for a single marker locus to characterize the effects of QTL. The methods are applied to the maize data of C. W. STUBER. The analyses strongly suggest that there are multiple linked QTL in many chromosomes for several traits examined. QTL effects are largely environment-independent for grain yield, ear height, plant height and ear leaf area and largely environment dependent for days to tassel, grain moisture and ear number. There is significant QTL epistasis. The results are generally in favor of the hypothesis of dominance of favorable genes to explain the observed heterosis in grain yield and other traits, although epistasis could also play an important role and overdominance at individual QTL level can not be ruled out. PMID:8807314

  13. Mark III results from SPEAR

    SciTech Connect

    Toki, W.

    1983-11-01

    First results from the MARK III detector at SPEAR are presented based on 2.7 million J/psi decays. The eta/sub c/ is observed in three modes, J/psi ..-->.. ..gamma..eta/sub c/, (eta/sub c/ ..-->.. rho anti rho, eta..pi../sup +/..pi../sup -/, and phi phi). Using the phi phi mode, the eta/sub c/ spin-parity is determined to be 0/sup -/. The known radiative J/psi decays J/psi ..-->.. ..gamma..f(f ..-->.. ..pi../sup +/..pi../sup -/), ..gamma..eta'(eta' ..-->.. ..gamma..rho/sup 0/, eta..pi../sup +/..pi../sup -/), ..gamma..f'(f' ..-->.. kappa/sup +/kappa/sup -/), ..gamma..theta(theta ..-->.. kappa anti kappa), and ..gamma..iota(iota ..-->.. ..pi..kappa anti kappa) are observed and their branching ratios found to be in agreement with previous measurements. In the J/psi ..-->.. ..gamma..kappa/sup +/kappa/sup -/ mode a new state is observed at 2.22 GeV and in the J/psi ..-->.. ..gamma gamma..rho/sup 0/ and ..gamma..eta..pi../sup +/..pi../sup -/ modes evidence for new structures near 1.4 GeV is presented. 29 references.

  14. III-V arsenide-nitride semiconductor

    NASA Technical Reports Server (NTRS)

    Major, Jo S. (Inventor); Welch, David F. (Inventor); Scifres, Donald R. (Inventor)

    2000-01-01

    III-V arsenide-nitride semiconductor are disclosed. Group III elements are combined with group V elements, including at least nitrogen and arsenic, in concentrations chosen to lattice match commercially available crystalline substrates. Epitaxial growth of these III-V crystals results in direct bandgap materials, which can be used in applications such as light emitting diodes and lasers. Varying the concentrations of the elements in the III-V materials varies the bandgaps, such that materials emitting light spanning the visible spectra, as well as mid-IR and near-UV emitters, can be created. Conversely, such material can be used to create devices that acquire light and convert the light to electricity, for applications such as full color photodetectors and solar energy collectors. The growth of the III-V material can be accomplished by growing thin layers of elements or compounds in sequences that result in the overall lattice match and bandgap desired.

  15. Separation studies of As(III), Sb(III) and Bi(III) by reversed-phase paper chromatographic technique

    SciTech Connect

    Raman, B.; Shinde, V.M.

    1987-07-01

    Reversed-phase paper chromatographic separations of As(III), Sb(III) and Bi(III) have been carried out on Whatman No 1 filter paper impregnated with triphenylphosphine oxide as stationary phase and using organic complexing agents such as sodium acetate, sodium succinate and sodium malonate solutions as active mobile phases. Results for the separation of binary and ternary mixtures are reported and the method has been successfully applied to the separation and detection of these elements present in real samples and at ppm level concentration.

  16. Lanthanide(III) and Yttrium(III) Complexes of Benzimidazole-2-Acetic Acid: Synthesis, Characterisation and Effect of La(III) Complex on Germination of Wheat

    PubMed Central

    Gudasi, Kalagouda B.; Shenoy, Rashmi V.; Vadavi, Ramesh S.; Patil, Manjula S.; Patil, Siddappa A.; Hanchinal, Rayappa R.; Desai, Srinivas A.; Lohithaswa, H.

    2006-01-01

    The synthesis and characterisation of lanthanide(III) and yttrium(III) nitrate complexes of benzimidazole-2-acetic acid (HBIA) are reported. The complexes have been characterised by elemental analysis, molar conductance, magnetic studies, IR, 1H NMR, UV-visible, EPR, and TG/DTA studies. They have the stoichiometry [Ln3(BIA)2(NO3)7(H2O)4] · 3H2O where Ln=La(III), Pr(III), Nd(II), Sm(III), Eu(III), Gd(III), Tb(III), Dy(III), and Y(III). The effect of La(III) complex on germination, coleoptile, and root length of two local varieties of wheat DWR-195 and GW-349 for different treatment periods has been investigated. The complex was found to exhibit enhanced activity, compared to HBIA or metal salt alone at lower treatment periods. PMID:17497017

  17. Neptunium(III) application in extraction chromatography.

    PubMed

    Guérin, Nicolas; Nadeau, Kenny; Larivière, Dominic

    2011-12-15

    This paper describes a novel strategy for actinide separation by extraction chromatography with Np(III) valence adjustment. Neptunium(IV) was reduced to Np(III) using Cr(II) and then selectively separated from uranium (IV) on a TEVA resin. After elution, Np(III) was retained on a DGA resin in order to remove any detrimental chromium impurities. Neptunium(III) formation was demonstrated by the complete and selective elution of Np from TEVA resin (99 ± 7%) in less than 12 mL of 9M HCl from U(IV) (0.7 ± 0.7%). It was determined by UV-visible and kinetic studies that Cr(II) was the only species responsible for the elution of Np(IV) as Np(III) and that the Cr(II) solution could be prepared from 2 to 30 min before its use without the need of complex degassing systems to prevent the oxidation of Np(III) by oxygen. The methodology proposed here with TEVA/DGA resins provides removal of Cr(III) impurities produced at high decontamination factors (2.8 × 10(3) and 7.3 × 10(4) respectively).

  18. Timely management of developing class III malocclusion.

    PubMed

    Yelampalli, M R; Rachala, M R

    2012-01-01

    Timing of orthodontic treatment, especially for children with developing class III malocclusions, has always been somewhat controversial, and definitive treatment tends to be delayed for severe class III cases. Developing class III patients with moderate to severe anterior crossbite and deep bite may need early intervention in some selected cases. Class III malocclusion may develop in children as a result of an inherent growth abnormality, i.e. true class III malocclusion, or as a result of premature occlusal contacts causing forward functional shift of the mandible, which is known as pseudo class III malocclusion. These cases, if not treated at the initial stage of development, interfere with normal growth of the jaw bases and may result in severe facial deformities. The treatment should be carried out as early as possible for permitting normal growth of the skeletal bases. This paper deals with the selection of an appropriate appliance from the various current options available for early intervention in developing class III malocclusion through two case reports.

  19. [Napoleon III's urogenital disease (1808-1873)].

    PubMed

    Androutsos, G

    2000-02-01

    We tried through this paper to reconstitute the evolution of the urologic illness of Napoleon III, last emperor of France, the first symptoms of which appeared many years before the fatal war of 1870, which led to the dismembering of France. In this connection, we present Napoleon III's physicians and his cures, along with the diagnostic and therapeutic errors. The case of Napoleon III is a typical example of the influence the bad health of a sovereign can exercise on the destiny of his country.

  20. Transcription by RNA polymerases I and III

    PubMed Central

    Paule, Marvin R.; White, Robert J.

    2000-01-01

    The task of transcribing nuclear genes is shared between three RNA polymerases in eukaryotes: RNA polymerase (pol) I synthesises the large rRNA, pol II synthesises mRNA and pol III synthesises tRNA and 5S rRNA. Although pol II has received most attention, pol I and pol III are together responsible for the bulk of transcriptional activity. This survey will summarise what is known about the process of transcription by pol I and pol III, how it happens and the proteins involved. Attention will be drawn to the similarities between the three nuclear RNA polymerase systems and also to their differences. PMID:10684922

  1. Photodetectors using III-V nitrides

    DOEpatents

    Moustakas, T.D.; Misra, M.

    1997-10-14

    A photodetector using a III-V nitride and having predetermined electrical properties is disclosed. The photodetector includes a substrate with interdigitated electrodes formed on its surface. The substrate has a sapphire base layer, a buffer layer formed from a III-V nitride and a single crystal III-V nitride film. The three layers are formed by electron cyclotron resonance microwave plasma-assisted molecular beam epitaxy (ECR-assisted MBE). Use of the ECR-assisted MBE process allows control and predetermination of the electrical properties of the photodetector. 24 figs.

  2. Photodetectors using III-V nitrides

    DOEpatents

    Moustakas, Theodore D.; Misra, Mira

    1997-01-01

    A photodetector using a III-V nitride and having predetermined electrical properties is disclosed. The photodetector includes a substrate with interdigitated electrodes formed on its surface. The substrate has a sapphire base layer, a buffer layer formed from a III-V nitride and a single crystal III-V nitride film. The three layers are formed by electron cyclotron resonance microwave plasma-assisted molecular beam epitaxy (ECR-assisted MBE). Use of the ECR-assisted MBE process allows control and predetermination of the electrical properties of the photodetector.

  3. Complexation of N4-Tetradentate Ligands with Nd(III) and Am(III)

    SciTech Connect

    Ogden, Mark D.; Sinkov, Sergey I.; Meier, G. Patrick; Lumetta, Gregg J.; Nash, Kenneth L.

    2012-12-06

    To improve understanding of aza-complexants in trivalent actinide–lanthanide separations, a series of tetradentate N-donor ligands have been synthesized and their complexation of americium(III) and neodymium(III) investigated by UV–visible spectrophotometry in methanolic solutions. The six pyridine/alkyl amine/imine ligands are N,N0-bis(2-methylpyridyl)-1,2-diaminoethane, N,N0-bis(2-methylpyridyl)-1,3-diaminopropane, trans-N,N-bis(2-pyridylmethyl)-1,2-diaminocyclohexane (BPMDAC), N,N’-bis(2-pyridylmethyl)piperazine, N,N’-bis-[pyridin-2-ylmethylene]ethane-1,2-diamine, and trans-N,Nbis-([pyridin-2-ylmethylene]-cyclohexane-1,2-diamine. Each ligand has two pyridine groups and two aliphatic amine/imine N-donor atoms arranged with different degrees of preorganization and structural backbone rigidity. Conditional stability constants for the complexes of Am(III) and Nd(III) by these ligands establish the selectivity patterns. The overall selectivity of Am(III) over Nd(III) is similar to that reported for the terdentate bis(dialkyltriazinyl)pyridine molecules. The cyclohexane amine derivative (BPMDAC) is the strongest complexant and shows the highest selectivity for Am(III) over Nd(III) while the imines appear to prefer a bridging arrangement between two cations. These results suggest that this series of ligands could be employed to develop an enhanced actinide(III)– lanthanide(III) separation system.

  4. Synthesis, thermal and spectroscopic behaviors of metal-drug complexes: La(III), Ce(III), Sm(III) and Y(III) amoxicillin trihydrate antibiotic drug complexes.

    PubMed

    Refat, Moamen S; Al-Maydama, Hussein M A; Al-Azab, Fathi M; Amin, Ragab R; Jamil, Yasmin M S

    2014-07-15

    The metal complexes of Amoxicillin trihydrate with La(III), Ce(III), Sm(III) and Y(III) are synthesized with 1:1 (metal:Amox) molar ratio. The suggested formula structures of the complexes are based on the results of the elemental analyses, molar conductivity, (infrared, UV-visible and fluorescence) spectra, effective magnetic moment in Bohr magnetons, as well as the thermal analysis (TG), and characterized by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The results obtained suggested that Amoxicillin reacted with metal ions as tridentate ligands, coordinating the metal ion through its amino, imino, and β-lactamic carbonyl. The kinetic thermodynamic parameters such as: Ea, ΔH(*), ΔS(*) and ΔG(*) were estimated from the DTG curves.

  5. Sorption of indium (III) onto carbon nanotubes.

    PubMed

    Alguacil, F J; Lopez, F A; Rodriguez, O; Martinez-Ramirez, S; Garcia-Diaz, I

    2016-08-01

    Indium has numerous applications in different industrial sectors and is not an abundant element. Therefore appropriate technology to recover this element from various process wastes is needed. This research reports high adsorption capacity of multiwalled carbon nanotubes (MWCNT) for In(III). The effects of pH, kinetics, isotherms and adsorption mechanism of MWCNT on In(III) adsorption were investigated and discussed in detail. The pH increases improves the adsorption capacity for In(III). The Langmuir adsorption model is the best fit with the experimental data. For the kinetic study, the adsorption onto MWCNT could be fitted to pseudo second-order. The adsorption of indium(III) can be described to a mechanism which consists of a film diffusion controlled process. Metal desorption can be achieved with acidic solutions.

  6. SAGE III capabilities and global change

    NASA Technical Reports Server (NTRS)

    Mccormick, M. Patrick

    1991-01-01

    The science objectives of the satellite-borne SAGE III are presented as they pertain to detecting global change. SAGE III is the proposed follow on and improved version of SAM II, SAGE I and SAGE II which have measured stratospheric and, in some cases, tropospheric species since late 1978. Specifically, SAGE III will measure profiles of aerosols, ozone, water vapor, nitrogen dioxide and trioxide, neutral density, temperature, clouds, and chlorine dioxide using the solar and lunar occultation techniques. These techniques are inherently self-calibrating, provide high vertical resolution, and use well-behaved data retrievals making them ideal for trend detection and global change studies. The potential capabilities of SAGE III are illustrated by using data and results from SAM II, SAGE I and SAGE II.

  7. Junto III: Collaboration Outreach by AAACE.

    ERIC Educational Resources Information Center

    Kasworm, Carol E.

    1986-01-01

    Discusses recommendations developed by Junto III of the American Association for Adult and Continuing Education concerning association responsibility, specific group action (full representation, socialization of new membership, generation of new research), and special needs. (CT)

  8. Level III and IV Ecoregions by State

    EPA Pesticide Factsheets

    Information and links to downloadable maps and datasets for Level III and IV ecoregions, listed by state. Ecoregions are areas of general similarity in the type, quality, and quantity of environmental resources.

  9. Genetics Home Reference: mucopolysaccharidosis type III

    MedlinePlus

    ... diagnosis of mucopolysaccharidosis III (Sanfilippo syndrome): A changing landscape. Mol Genet Metab. 2014 Sep-Oct;113(1- ... j.1651-2227.2010.01800.x. Epub 2010 Mar 14. Citation on PubMed Meyer A, Kossow K, ...

  10. Isolatable organophosphorus(III)-tellurium heterocycles.

    PubMed

    Nordheider, Andreas; Chivers, Tristram; Schön, Oliver; Karaghiosoff, Konstantin; Athukorala Arachchige, Kasun S; Slawin, Alexandra M Z; Woollins, J Derek

    2014-01-13

    A new structural arrangement Te3 (RP(III) )3 and the first crystal structures of organophosphorus(III)-tellurium heterocycles are presented. The heterocycles can be stabilized and structurally characterized by the appropriate choice of substituents in Tem (P(III) R)n (m=1: n=2, R=OMes* (Mes*=supermesityl or 2,4,6-tri-tert-butylphenyl); n=3, R=adamantyl (Ad); n=4, R=ferrocene (Fc); m=n=3: R=trityl (Trt), Mesor by the installation of a P(V) 2 N2 anchor in RP(III) [TeP(V) (tBuN)(μ-NtBu)]2 (R=Ad, tBu).

  11. Potentiometry: A Chromium (III) -- EDTA Complex

    ERIC Educational Resources Information Center

    Hoppe, J. I.; Howell, P. J.

    1975-01-01

    Describes an experiment that involves the preparation of a chromium (III)-EDTA compound, a study of its infrared spectrum, and the potentiometric determination of two successive acid dissociation constants. (Author/GS)

  12. SAGE III/Meteor - 3M

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Back view of the SAGE III Bench Checkout Unit, Portable Image Generator (PIG) on tripod, and the Stratospheric Aerosol Gastropheric Experiment (SAGE)/Meteor - 3M flight instrument. Photographed in building 1250, 40 foot clean room.

  13. SAGE III/Meteor - 3M

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Full view of the SAGE III Bench Checkout Unit, Collimated Source Bench (CSB), Portable Image Generator (PIG) on tripod, and Stratospheric Aerosol Gastropheric Experiment (SAGE)/Meteor - 3M flight instrument. Photographed in building 1250, 40 foot clean room.

  14. Population III Stars Around the Milky Way

    NASA Astrophysics Data System (ADS)

    Komiya, Yutaka; Suda, Takuma; Fujimoto, Masayuki Y.

    2016-03-01

    We explore the possibility of observing Population III (Pop III) stars, born of primordial gas. Pop III stars with masses below 0.8 M⊙ should survive to date though are not yet observed, but the existence of stars with low metallicity as [{{Fe}}/{{H}}]\\lt -5 in the Milky Way halo suggests the surface pollution of Pop III stars with accreted metals from the interstellar gas after birth. In this paper, we investigate the runaway of Pop III stars from their host mini-halos, considering the ejection of secondary members from binary systems when their massive primaries explode as supernovae. These stars save them from surface pollution. By computing the star formation and chemical evolution along with the hierarchical structure formation based on the extended Press-Schechter merger trees, we demonstrate that several hundreds to tens of thousands of low-mass Pop III stars escape from the building blocks of the Milky Way. The second and later generations of extremely metal-poor stars also escaped from the mini-halos. We discuss the spatial distributions of these escaped stars by evaluating the distances between the mini-halos in the branches of merger trees under the spherical collapse model of dark matter halos. It is demonstrated that the escaped stars distribute beyond the stellar halo with a density profile close to the dark matter halo, while Pop III stars are slightly more centrally concentrated. 6%-30% of the escaped stars leave the Milky Way and go out into the intergalactic space. Based on the results, we discuss the feasibility of observing the Pop III stars with the pristine surface abundance.

  15. SAGE III solar ozone measurements: Initial results

    NASA Technical Reports Server (NTRS)

    Wang, Hsiang-Jui; Cunnold, Derek M.; Trepte, Chip; Thomason, Larry W.; Zawodny, Joseph M.

    2006-01-01

    Results from two retrieval algorithms, o3-aer and o3-mlr , used for SAGE III solar occultation ozone measurements in the stratosphere and upper troposphere are compared. The main differences between these two retrieved (version 3.0) ozone are found at altitudes above 40 km and below 15 km. Compared to correlative measurements, the SAGE II type ozone retrievals (o3-aer) provide better precisions above 40 km and do not induce artificial hemispheric differences in upper stratospheric ozone. The multiple linear regression technique (o3_mlr), however, can yield slightly more accurate ozone (by a few percent) in the lower stratosphere and upper troposphere. By using SAGE III (version 3.0) ozone from both algorithms and in their preferred regions, the agreement between SAGE III and correlative measurements is shown to be approx.5% down to 17 km. Below 17 km SAGE III ozone values are systematically higher, by 10% at 13 km, and a small hemispheric difference (a few percent) appears. Compared to SAGE III and HALOE, SAGE II ozone has the best accuracy in the lowest few kilometers of the stratosphere. Estimated precision in SAGE III ozone is about 5% or better between 20 and 40 km and approx.10% at 50 km. The precision below 20 km is difficult to evaluate because of limited coincidences between SAGE III and sondes. SAGE III ozone values are systematically slightly larger (2-3%) than those from SAGE II but the profile shapes are remarkably similar for altitudes above 15 km. There is no evidence of any relative drift or time dependent differences between these two instruments for altitudes above 15-20 km.

  16. Design of Training Systems Phase III Report

    DTIC Science & Technology

    1975-09-01

    as the reader is aware of this approach and relies on the T&E Report for a more detailed analysis , this summary should highlight the key T&E concerns... ANALYSIS AND EVALUATION GROUP LIBRARY TECHNICAL REPORT SECTION NAVAL POSTGRADUATE S^ MONTEREY CALliChMA TAEG REPORT NO. 28 DESIGN...EVALUATION SUMMARY I II-l IV PHASE III PRODUCTS CONCLUSIONS AND RECOMMENDATIONS IV-1 PHASE III DOCUMENTATION IV-7 11 TAE6 REPORT NO. 28

  17. Development of WAIS-III General Ability Index Minus WMS-III memory discrepancy scores.

    PubMed

    Lange, Rael T; Chelune, Gordon J; Tulsky, David S

    2006-09-01

    Analysis of the discrepancy between intellectual functioning and memory ability has received some support as a useful means for evaluating memory impairment. In recent additions to Wechlser scale interpretation, the WAIS-III General Ability Index (GAI) and the WMS-III Delayed Memory Index (DMI) were developed. The purpose of this investigation is to develop base rate data for GAI-IMI, GAI-GMI, and GAI-DMI discrepancy scores using data from the WAIS-III/WMS-III standardization sample (weighted N = 1250). Base rate tables were developed using the predicted-difference method and two simple-difference methods (i.e., stratified and non-stratified). These tables provide valuable data for clinical reference purposes to determine the frequency of GAI-IMI, GAI-GMI, and GAI-DMI discrepancy scores in the WAIS-III/WMS-III standardization sample.

  18. Lanthanum(III) and praseodymium(III) derivatives with dithiocarbamates derived from alpha-amino acids.

    PubMed

    Rai, Anita; Sengupta, Soumitra K; Pandey, Om P

    2006-06-01

    Lanthanum(III) and praseodymium(III) complexes with dithiocarbamates have been synthesized by the reactions of lanthanum(III) and praseodymium(III) chloride with barium dithiocarbamate and complexes of type [LnCl(L)H2O]n have been obtained (where Ln=La(III) or Pr(III); L=barium salt of dithiocarbamate derived from glycine, L-leucine, L-valine, DL-alanine). The complexes have been characterized by elemental analysis, molar conductance, electronic absorption and fluorescence, infrared, far infrared, 1H NMR spectral studies. The presence of coordinated water molecule is inferred from thermogravimetric analysis which indicates the loss of one water molecule at 150-170 degrees C. The oscillator strength, Judd-Ofelt intensity parameter, stimulated emission cross-section, etc. have been obtained for different transitions of Pr3+.

  19. Helical lanthanide(III) complexes with chiral nonaaza macrocycle.

    PubMed

    Gregoliński, Janusz; Starynowicz, Przemysław; Hua, KimNgan T; Lunkley, Jamie L; Muller, Gilles; Lisowski, Jerzy

    2008-12-31

    The chiral nonaazamacrocyclic amine L, which is a reduction product of the 3 + 3 Schiff base macrocycle, wraps around the lanthanide(III) ions to form enantiopure helical complexes. These Ce(III), Pr(III), Nd(III), Eu(III), Gd(III), Tb(III), Er(III), Yb(III) and Lu(III) complexes have been isolated in enantiopure form and have been characterized by spectroscopic methods. X-ray crystal structures of the Ln(III) complexes with L show that the thermodynamic product of the complexation of the RRRRRR-isomer of the macrocycle is the (M)-helical complex in the case of Ce(III), Pr(III), Nd(III) and Eu(III). In contrast, the (P)-helical complex is the thermodynamic product in the case of Yb(III) and Lu(III). The NMR and CD spectra show that the (M)-helicity for the kinetic complexation product of the RRRRRR-isomer of the macrocycle is preferred for all investigated lanthanide(III) ions, while the preferred helicity of the thermodynamic product is (M) for the early lanthanide(III) ions and (P) for the late lanthanide(III) ions. In the case of the late lanthanide(III) ions, a slow inversion of helicity between the kinetic (M)-helical product and the thermodynamic (P)-helical product is observed in solution. For Er(III), Yb(III) and Lu(III) both forms have been isolated in pure form and characterized by NMR and CD. The analysis of 2D NMR spectra of the Lu(III) complex reveals the NOE correlations that prove that the helical structure is retained in solution. The NMR spectra also reveal large isotopic effect on the 1H NMR shifts of paramagnetic Ln(III) complexes, related to NH/ND exchange. Photophysical measurements show that L(RRRRRR) appears to favor an efficient 3pipi*-to-Ln energy transfer process taking place for Eu(III) and Tb(III), but these Eu(III)- and Tb(III)-containing complexes with L(RRRRRR) lead to small luminescent quantum yields due to an incomplete intersystem crossing (isc) transfer, a weak efficiency of the luminescence sensitization by the ligand, and

  20. WAIS-III and WMS-III profiles of mildly to severely brain-injured patients.

    PubMed

    Fisher, D C; Ledbetter, M F; Cohen, N J; Marmor, D; Tulsky, D S

    2000-01-01

    Wechsler Adult Intelligence Scale-III (WAIS-III) and Wechsler Memory Scale-III (WMS-III; The Psychological Corporation, 1997) scores of patients with mild traumatic brain injury (MTBI, n = 23) to moderate-severe traumatic brain injury (M-S TBI, n = 22) were compared to those of 45 matched normal control patients. WAIS-III results revealed that IQ and index scores of MTBI patients did not significantly differ from those of controls, whereas M-S TBI patients received significantly lower mean scores on all measures. All M-S TBI patients' WMS-III index scores also revealed significantly lower scores in comparison to those of control participants, with the exception of Delayed Auditory Recognition. MTBI patients showed significantly lower mean index scores compared to normal controls on measures of immediate and delayed auditory memory, immediate memory, visual delayed memory, and general memory. Eta-squared analyses revealed that WMS-III visual indexes and WAIS-III processing speed showed particularly large effect sizes. These results suggest that symptomatic MTBI patients obtain some low WMS-III test scores comparable to those of more severely injured patients.

  1. Design of Integrated III-Nitride/Non-III-Nitride Tandem Photovoltaic Devices

    SciTech Connect

    Toledo, N. G.; Friedman, D..J.; Farrell, R. M.; Perl, E. E.; Lin, C. T.; Bowers, J. E.; Speck, J. S.; Mishra, U. K.

    2012-03-01

    The integration of III-nitride and non-III-nitride materials for tandem solar cell applications can improve the efficiency of the photovoltaic device due to the added power contributed by the III-nitride top cell to that of high-efficiency multi-junction non-III-nitride solar cells if the device components are properly designed and optimized. The proposed tandem solar cell is comprised of a III-nitride top cell bonded to a non-III-nitride, series-constrained, multi-junction subcell. The top cell is electrically isolated, but optically coupled to the underlying subcell. The use of a III-nitride top cell is potentially beneficial when the top junction of a stand-alone non-III-nitride subcell generates more photocurrent than the limiting current of the non-III-nitride subcell. Light producing this excess current can either be redirected to the III-nitride top cell through high energy photon absorption, redirected to the lower junctions through layer thickness optimization, or a combination of both, resulting in improved total efficiency. When the non-III-nitride cell's top junction is the limiting junction, the minimum power conversion efficiency that the III-nitride top cell must contribute should compensate for the spectrum filtered from the multi-junction subcell for this design to be useful. As the III-nitride absorption edge wavelength, {lambda}{sub N}, increases, the performance of the multi-junction subcell decreases due to spectral filtering. In the most common spectra of interest (AM1.5G, AM1.5 D, and AM0), the technology to grow InGaN cells with {lambda}{sub N}<520 nm is found to be sufficient for III-nitride top cell applications. The external quantum efficiency performance, however, of state-of-the-art InGaN solar cells still needs to be improved. The effects of surface/interface reflections are also presented. The management of these reflection issues determines the feasibility of the integrated III-nitride/non-III-nitride design to improve overall cell

  2. Comparative serum albumin interactions and antitumor effects of Au(III) and Ga(III) ions.

    PubMed

    Sarioglu, Omer Faruk; Ozdemir, Ayse; Karaboduk, Kuddusi; Tekinay, Turgay

    2015-01-01

    In the present study, interactions of Au(III) and Ga(III) ions on human serum albumin (HSA) were studied comparatively via spectroscopic and thermal analysis methods: UV-vis absorbance spectroscopy, fluorescence spectroscopy, Fourier transform infrared (FT-IR) spectroscopy and isothermal titration calorimetry (ITC). The potential antitumor effects of these ions were studied on MCF-7 cells via Alamar blue assay. It was found that both Au(III) and Ga(III) ions can interact with HSA, however; Au(III) ions interact with HSA more favorably and with a higher affinity. FT-IR second derivative analysis results demonstrated that, high concentrations of both metal ions led to a considerable decrease in the α-helix content of HSA; while Au(III) led to around 5% of decrease in the α-helix content at 200μM, it was around 1% for Ga(III) at the same concentration. Calorimetric analysis gave the binding kinetics of metal-HSA interactions; while the binding affinity (Ka) of Au(III)-HSA binding was around 3.87×10(5)M(-1), it was around 9.68×10(3)M(-1) for Ga(III)-HSA binding. Spectroscopy studies overall suggest that both metal ions have significant effects on the chemical structure of HSA, including the secondary structure alterations. Antitumor activity studies on MCF7 tumor cell line with both metal ions revealed that, Au(III) ions have a higher antiproliferative activity compared to Ga(III) ions.

  3. Sorption of phosphate and Cr(VI) by Fe(III) and Cr(III) hydroxides.

    PubMed

    Tzou, Y M; Wang, M K; Loeppert, R H

    2003-05-01

    Understanding the chemical behavior and interactions of Cr(VI) ( e.g., HCrO(4)(-)) and other anions, such as orthophosphate (P) with insoluble metal hydroxides ( i.e., Cr[III] and Fe[III]) in disposal landfills or in chromite ore processing residue (CORP)-enriched soil is very important in predicting the movement and the fate of Cr(VI). This study evaluates the sorption behavior of P and Cr(VI) by Fe(III) ( i.e., ferrihydrite), Cr(III) ( i.e., Cr[OH](3)), and coprecipitated Fe(III)/Cr(III) hydroxides. These metal hydroxide sorbents were synthesized, and sorption of P and Cr(VI) were conducted at different pH using a batch technology. Our results show that P and Cr(VI) sorption by metal hydroxides decreased with increasing suspension pH. Greater decrease in P sorption was observed when Cr(III) was present in the structures of hydroxides. Following the sorption of low concentration of P ( i.e., 0.5 mM), the sorption of subsequently added Cr(VI) by hydroxides was less influenced. However, Cr(VI) sorption was greatly inhibited when high concentration of P ( i.e., 10 mM) prereacted with hydroxides, particularly in Fe(III) hydroxide system. Results also indicated that high concentration of Cr(VI) (10 mM) could dissolve Cr(III) hydroxide at pH 3 and reprecipitate as an amorphous form of Cr(VI) and Cr(III) compound at pH about 6.5. Although coprecipitation of Cr(VI) with Cr(III) can inhibit Cr(VI) movement through soil profiles, the inhibition seems to be low due to the gradual release of Cr(VI) with increasing pH.

  4. Sparkle/PM3 Parameters for the Modeling of Neodymium(III), Promethium(III), and Samarium(III) Complexes.

    PubMed

    Freire, Ricardo O; da Costa, Nivan B; Rocha, Gerd B; Simas, Alfredo M

    2007-07-01

    The Sparkle/PM3 model is extended to neodymium(III), promethium(III), and samarium(III) complexes. The unsigned mean error, for all Sparkle/PM3 interatomic distances between the trivalent lanthanide ion and the ligand atoms of the first sphere of coordination, is 0.074 Å for Nd(III); 0.057 Å for Pm(III); and 0.075 Å for Sm(III). These figures are similar to the Sparkle/AM1 ones of 0.076 Å, 0.059 Å, and 0.075 Å, respectively, indicating they are all comparable models. Moreover, their accuracy is similar to what can be obtained by present-day ab initio effective potential calculations on such lanthanide complexes. Hence, the choice of which model to utilize will depend on the assessment of the effect of either AM1 or PM3 on the quantum chemical description of the organic ligands. Finally, we present a preliminary attempt to verify the geometry prediction consistency of Sparkle/PM3. Since lanthanide complexes are usually flexible, we randomly generated 200 different input geometries for the samarium complex QIPQOV which were then fully optimized by Sparkle/PM3. A trend appeared in that, on average, the lower the total energy of the local minima found, the lower the unsigned mean errors, and the higher the accuracy of the model. These preliminary results do indicate that attempting to find, with Sparkle/PM3, a global minimum for the geometry of a given complex, with the understanding that it will tend to be closer to the experimental geometry, appears to be warranted. Therefore, the sparkle model is seemingly a trustworthy semiempirical quantum chemical model for the prediction of lanthanide complexes geometries.

  5. Failures in Phase III: Causes and Consequences.

    PubMed

    Seruga, Bostjan; Ocana, Alberto; Amir, Eitan; Tannock, Ian F

    2015-10-15

    Phase III randomized controlled trials (RCT) in oncology fail to lead to registration of new therapies more often than RCTs in other medical disciplines. Most RCTs are sponsored by the pharmaceutical industry, which reflects industry's increasing responsibility in cancer drug development. Many preclinical models are unreliable for evaluation of new anticancer agents, and stronger evidence of biologic effect should be required before a new agent enters the clinical development pathway. Whenever possible, early-phase clinical trials should include pharmacodynamic studies to demonstrate that new agents inhibit their molecular targets and demonstrate substantial antitumor activity at tolerated doses in an enriched population of patients. Here, we review recent RCTs and found that these conditions were not met for most of the targeted anticancer agents, which failed in recent RCTs. Many recent phase III RCTs were initiated without sufficient evidence of activity from early-phase clinical trials. Because patients treated within such trials can be harmed, they should not be undertaken. The bar should also be raised when making decisions to proceed from phase II to III and from phase III to marketing approval. Many approved agents showed only better progression-free survival than standard treatment in phase III trials and were not shown to improve survival or its quality. Introduction of value-based pricing of new anticancer agents would dissuade the continued development of agents with borderline activity in early-phase clinical trials. When collaborating with industry, oncologists should be more critical and better advocates for cancer patients.

  6. Hybrid III-V/silicon lasers

    NASA Astrophysics Data System (ADS)

    Kaspar, P.; Jany, C.; Le Liepvre, A.; Accard, A.; Lamponi, M.; Make, D.; Levaufre, G.; Girard, N.; Lelarge, F.; Shen, A.; Charbonnier, P.; Mallecot, F.; Duan, G.-H.; Gentner, J.-.; Fedeli, J.-M.; Olivier, S.; Descos, A.; Ben Bakir, B.; Messaoudene, S.; Bordel, D.; Malhouitre, S.; Kopp, C.; Menezo, S.

    2014-05-01

    The lack of potent integrated light emitters is one of the bottlenecks that have so far hindered the silicon photonics platform from revolutionizing the communication market. Photonic circuits with integrated light sources have the potential to address a wide range of applications from short-distance data communication to long-haul optical transmission. Notably, the integration of lasers would allow saving large assembly costs and reduce the footprint of optoelectronic products by combining photonic and microelectronic functionalities on a single chip. Since silicon and germanium-based sources are still in their infancy, hybrid approaches using III-V semiconductor materials are currently pursued by several research laboratories in academia as well as in industry. In this paper we review recent developments of hybrid III-V/silicon lasers and discuss the advantages and drawbacks of several integration schemes. The integration approach followed in our laboratory makes use of wafer-bonded III-V material on structured silicon-on-insulator substrates and is based on adiabatic mode transfers between silicon and III-V waveguides. We will highlight some of the most interesting results from devices such as wavelength-tunable lasers and AWG lasers. The good performance demonstrates that an efficient mode transfer can be achieved between III-V and silicon waveguides and encourages further research efforts in this direction.

  7. Luminescent xerogels obtained through embedding Tb(III) and Eu(III) complexes in silica matrix

    NASA Astrophysics Data System (ADS)

    Stan, Corneliu S.; Marcotte, Nathalie; Secula, Marius S.; Popa, Marcel

    2013-07-01

    The paper reports the preparation of two luminescent xerogels through embedding in a silica matrix of Tb(III) and Eu(III) complexes using succinimide (SI) and N-hydroxysuccinimide (NHSI) as ligands. In the first stage, Tb(III) and Eu(III) complexes with N-hydroxysuccinimide and succinimide were prepared at 1:3 metal to ligand ratio. Strong luminescent emission was observed only in case of Eu(III)-SI and Tb(III)-NHSI complexes while the Eu(III)-NHSI and Tb(III)-SI complexes exhibited none or weak photoluminescent properties. In the second stage, the selected highly luminescent complexes were embedded in silica matrices via a sol-gel procedure leading to the formation of xerogels with transparent-glassy aspect which keep the remarkable photoluminescence properties of the free complexes. The selected, highly luminescent free complexes and their correspondent silica xerogels were investigated through thermal analysis, powder XRD, SEM, FT-IR and fluorescence spectroscopy. Their excellent photoluminescent properties and excitation spectra, conveniently located in UV-A region, might recommend these materials for applications in optoelectronic devices where photonic conversion layers are required.

  8. Novel, highly photoluminescent Eu(III) and Tb(III) tetrazolate-2-pyridine-1-oxide complexes

    NASA Astrophysics Data System (ADS)

    Pietraszkiewicz, Marek; Mal, Suraj; Pietraszkiewicz, Oksana

    2012-07-01

    Tetrazole-2-pyridine-1-oxide was prepared from 2-cyanopyridine and sodium azide, followed by oxidation with m-chloroperbenzoic acid. This ligand forms neutral 1:3 complexes with Eu(III) and Tb(III) cations. The complexes are photoluminescent in solution, with photoluminescence quantum yields 13% and 31%, respectively.

  9. Sensitivity and specificity of WAIS-III/WMS-III demographically corrected factor scores in neuropsychological assessment.

    PubMed

    Taylor, M J; Heaton, R K

    2001-11-01

    This study explored the neurodiagnostic utility of 6 factor scores identified by recent exploratory and confirmatory factor analyses of the WAIS-III and WMS-III: Verbal Comprehension, Perceptual Organization, Processing Speed, Working Memory, Auditory Memory and Visual Memory. Factor scores were corrected for age. education, sex and ethnicity to minimize their influences on diagnostic accuracy. Cut-offs at 1, 1.5 and 2 standard deviations (SDs) below the standardization sample mean were applied to data from the overlapping test normative samples (N = 1073) and 6 clinical samples described in the WAIS-III/WMS-III Technical Manual (N = 126). The analyses suggest that a I SD cut-off yields the most balanced levels of sensitivity and specificity; more strict (1.5 or 2 SD) cut-offs generally result in trading modest gains in specificity for larger losses in sensitivity. Finally, using combinations of WAIS-III/WMS-III factors together as test batteries, we explored the sensitivity and specificity implications of varying diagnostic decision rules (e.g.,1 vs. 2 impaired factors = "impairment"). For most of the disorders considered here, even a small (e.g., 3 factor) WAIS-III/WMS-III battery provides quite good overall diagnostic accuracy.

  10. Teachers' Guide to Music Appreciation III A and III B in the Senior High School.

    ERIC Educational Resources Information Center

    Scott, J. Mark; Dawkins, Barbara R.

    This guide to music appreciation courses was developed for use in senior high schools in Duval County, Jacksonville, Florida. Music Appreciation III A examines the development of music, from the Gothic period through the Classical period. Music Appreciation III B examines the development of music from the Romantic period through the 1970s.…

  11. Synthesis, crystal structure and magnetism of iron(III) and manganese(III) dipicolinates with pyridinemethanols

    NASA Astrophysics Data System (ADS)

    Uhrecký, Róbert; Pavlik, Ján; Růžičková, Zdeňka; Dlháň, Ľubor; Koman, Marian; Boča, Roman; Moncoľ, Ján

    2014-11-01

    Four ionic iron(III) and manganese(III) dipicolinato complexes of the formula (2-pymeH) [FeIII(dipic)2]ṡ[FeIII(H2O)2Cl(dipic)]ṡ2H2O, (3-pymeH)[MnIII(dipic)2]ṡ1.5H2O, (4-pymeH)[FeIII(dipic)2]ṡ2H2O and (4-pymeH)[MnIII(dipic)2]ṡ2H2O, where H2dipic = pyridine-2,6-dicarboxylic acid, 2-pyme = 2-pyridinemethanol, 3-pyme = 3-pyridinemethanol, 4-pyme = 4-pyridinemethanol, have been prepared and characterized by the single-crystal X-ray structure analysis, infrared spectroscopy and magnetic measurements. The magnetic data were fitted to a zero-field splitting model revealing a slight magnetic anisotropy for Mn(III) systems. The molecular field correction was consistently formulated and included in the analysis for both, magnetic susceptibility and magnetization data.

  12. Hexaammine Complexes of Cr(III) and Co(III): A Spectral Study.

    ERIC Educational Resources Information Center

    Brown, D. R.; Pavlis, R. R.

    1985-01-01

    Procedures are provided for experiments containing complex ions with octahedral symmetry, hexaamminecobalt(III) chloride and hexaamminechromium(III) nitrate, so students can interpret fully the ultra violet/visible spectra of the complex cations in terms of the ligand field parameters, 10 "Dq," the Racah interelectron repulsion parameters, "B,"…

  13. Molten-Salt-Based Growth of Group III Nitrides

    DOEpatents

    Waldrip, Karen E.; Tsao, Jeffrey Y.; Kerley, Thomas M.

    2008-10-14

    A method for growing Group III nitride materials using a molten halide salt as a solvent to solubilize the Group-III ions and nitride ions that react to form the Group III nitride material. The concentration of at least one of the nitride ion or Group III cation is determined by electrochemical generation of the ions.

  14. 46 CFR 50.30-20 - Class III pressure vessels.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 2 2012-10-01 2012-10-01 false Class III pressure vessels. 50.30-20 Section 50.30-20... Fabrication Inspection § 50.30-20 Class III pressure vessels. (a) Class III pressure vessels shall be subject... specifically exempted by other regulations in this subchapter. (b) For Class III welded pressure vessels,...

  15. 46 CFR 50.30-20 - Class III pressure vessels.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Class III pressure vessels. 50.30-20 Section 50.30-20... Fabrication Inspection § 50.30-20 Class III pressure vessels. (a) Class III pressure vessels shall be subject... specifically exempted by other regulations in this subchapter. (b) For Class III welded pressure vessels,...

  16. 46 CFR 50.30-20 - Class III pressure vessels.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 2 2011-10-01 2011-10-01 false Class III pressure vessels. 50.30-20 Section 50.30-20... Fabrication Inspection § 50.30-20 Class III pressure vessels. (a) Class III pressure vessels shall be subject... specifically exempted by other regulations in this subchapter. (b) For Class III welded pressure vessels,...

  17. 46 CFR 50.30-20 - Class III pressure vessels.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 2 2013-10-01 2013-10-01 false Class III pressure vessels. 50.30-20 Section 50.30-20... Fabrication Inspection § 50.30-20 Class III pressure vessels. (a) Class III pressure vessels shall be subject... specifically exempted by other regulations in this subchapter. (b) For Class III welded pressure vessels,...

  18. 46 CFR 50.30-20 - Class III pressure vessels.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 2 2014-10-01 2014-10-01 false Class III pressure vessels. 50.30-20 Section 50.30-20... Fabrication Inspection § 50.30-20 Class III pressure vessels. (a) Class III pressure vessels shall be subject... specifically exempted by other regulations in this subchapter. (b) For Class III welded pressure vessels,...

  19. Psychometric Testing of the FACES III with Rural Adolescents

    ERIC Educational Resources Information Center

    Ide, Bette; Dingmann, Colleen; Cuevas, Elizabeth; Meehan, Maurita

    2010-01-01

    This study tests the validity and reliability of the Family Adaptability and Cohesion Scale III (FACES III) in two samples of rural adolescents. The underlying theory is the linear 3-D circumplex model. The FACES III was administered to 1,632 adolescents in Grades 7 through 12 in two counties in a rural western state. The FACES III Scale and the…

  20. Discrepancies between the [O iii] and [S iii] temperatures in H ii regions

    NASA Astrophysics Data System (ADS)

    Binette, L.; Matadamas, R.; Hägele, G. F.; Nicholls, D. C.; Magris C., G.; Peña-Guerrero, M. Á.; Morisset, C.; Rodríguez-González, A.

    2012-11-01

    Context. Analysis of published [O iii] and [S iii] temperatures measurements of emission line objects consisting of Hii galaxies, giant extragalactic Hii regions, Galactic Hii regions, and Hii regions from the Magellanic Clouds reveal that the [O iii] temperatures are higher than the corresponding values from [S iii] in most objects with gas metallicities in excess of 0.2 solar. For the coolest nebulae (the highest metallicities), the [O iii] temperature excess can reach ~3000 K. Aims: We look for an explanation for these temperature differences and explore the parameter space of models with the aim of reproducing the observed trend of TO iii > TS iii in Hii regions with temperatures below 14 000 K. Methods: Using standard photoionization models, we varied the ionization parameter, the hardness of the ionizing continuum, and the gas metallicities in order to characterize how models behave with respect to the observations. We introduced temperature inhomogeneities and varied their mean squared amplitude t2 . We explored the possibility of inhomogeneities in abundances by combining two models of widely different metallicity. We calculated models that consider the possibility of a non-Maxwell-Boltzmann energy distribution (a κ-distribution) for the electron energies. We also considered shock heating within the photoionized nebula. Results: Simple photoionization calculations yield nearly equal [O iii] and [S iii] temperatures in the domain of interest. Hence these models fail to reproduce the [O iii] temperature excess. Models that consider temperature inhomogeneities, as measured by the mean squared amplitude t2 , also fail in the regime where TO iii < 14 000 K. Three options remain that can reproduce the observed excess in TO iii temperatures: (1) large metallicity inhomogeneities in the nebula; a (2) κ-distribution for the electron energies; and (3) shock waves that propagate in the photoionized plasma at velocities ~60 km s-1. Conclusions: The observed nebular

  1. Solidity of Type III Bernoulli Crossed Products

    NASA Astrophysics Data System (ADS)

    Marrakchi, Amine

    2017-03-01

    We generalize a theorem of Chifan and Ioana by proving that for any, possibly type III, amenable von Neumann algebra A 0, any faithful normal state φ_0 and any discrete group {Γ}, the associated Bernoulli crossed product von Neumann algebra {M=(A_0,φ_0)^{overline{⊗} Γ} rtimes Γ} is solid relatively to L(Γ). In particular, if L(Γ) is solid then M is solid and if {Γ} is non-amenable and {A_0 ≠ C then M is a full prime factor. This gives many new examples of solid or prime type III factors. Following Chifan and Ioana, we also obtain the first examples of solid non-amenable type III equivalence relations.

  2. Evolution of Class III treatment in orthodontics.

    PubMed

    Ngan, Peter; Moon, Won

    2015-07-01

    Angle, Tweed, and Moyers classified Class III malocclusions into 3 types: pseudo, dentoalveolar, and skeletal. Clinicians have been trying to identify the best timing to intercept a Class III malocclusion that develops as early as the deciduous dentition. With microimplants as skeletal anchorage, orthopedic growth modification became more effective, and it also increased the scope of camouflage orthodontic treatment for patients who were not eligible for orthognathic surgery. However, orthodontic treatment combined with orthognathic surgery remains the only option for patients with a severe skeletal Class III malocclusion or a craniofacial anomaly. Distraction osteogenesis can now be performed intraorally at an earlier age. The surgery-first approach can minimize the length of time that the malocclusion needs to worsen before orthognathic surgery. Finally, the use of computed tomography scans for 3-dimensional diagnosis and treatment planning together with advances in imaging technology can improve the accuracy of surgical movements and the esthetic outcomes for these patients.

  3. SAGE III Aerosol Extinction Validation in the Arctic Winter: Comparisons with SAGE II and POAM III

    NASA Technical Reports Server (NTRS)

    Thomason, L. W.; Poole, L. R.; Randall, C. E.

    2007-01-01

    The use of SAGE III multiwavelength aerosol extinction coefficient measurements to infer PSC type is contingent on the robustness of both the extinction magnitude and its spectral variation. Past validation with SAGE II and other similar measurements has shown that the SAGE III extinction coefficient measurements are reliable though the comparisons have been greatly weighted toward measurements made at mid-latitudes. Some aerosol comparisons made in the Arctic winter as a part of SOLVE II suggested that SAGE III values, particularly at longer wavelengths, are too small with the implication that both the magnitude and the wavelength dependence are not reliable. Comparisons with POAM III have also suggested a similar discrepancy. Herein, we use SAGE II data as a common standard for comparison of SAGE III and POAM III measurements in the Arctic winters of 2002/2003 through 2004/2005. During the winter, SAGE II measurements are made infrequently at the same latitudes as these instruments. We have mitigated this problem through the use potential vorticity as a spatial coordinate and thus greatly increased the number of coincident events. We find that SAGE II and III extinction coefficient measurements show a high degree of compatibility at both 1020 nm and 450 nm except a 10-20% bias at both wavelengths. In addition, the 452 to 1020-nm extinction ratio shows a consistent bias of approx. 30% throughout the lower stratosphere. We also find that SAGE II and POAM III are on average consistent though the comparisons show a much higher variability and larger bias than SAGE II/III comparisons. In addition, we find that the two data sets are not well correlated below 18 km. Overall, we find both the extinction values and the spectral dependence from SAGE III are robust and we find no evidence of a significant defect within the Arctic vortex.

  4. Complexation of Cm(III)/Eu(III) with Silicate in Basic Solutions

    SciTech Connect

    Wang, Zheming; Felmy, Andrew R; Xia, Yuanxian; Qafoku, Odeta; Yantasee, Wassana; Cho, Herman M

    2005-12-01

    The complexation of Cm(III) and Eu(III) with dissolved silica was studied by time resolved laser fluorescence spectroscopy (TRLFS) in basic solutions over a range of total silica concentrations and ionic strengths (NaNO3). In highly basic solutions, both the fluorescence spectra and lifetime data indicate the formation of Eu(III)/Cm(III) complexes with oligomeric silicates as well as hydroxide groups and/or nitrate in the presence of concentrated NaNO3. At high silica concentration the inner-sphere complexation caused the shift of the fluorescence spectral maximum for Cm(III)(aq) from 594 nm to up to 607 nm and a significant increase of the hypersensitive 5D0 → 7F2 band around 615 nm relative to the non-hypersensitive 5D0 → 7F1 band at 592 nm for Eu(III). At the same time, the fluorescence lifetime increased from 68 s to up to 202 s for Cm(III) in 0.1 M NaNO3 and from 115 s to 1.8 ms for Eu(III) in 3.0 M and 5.0 M NaNO3, consistent with the removal of 6 or more water molecules upon silicate complexation. Linear correlations between the spectral intensity of Cm(III) complexes and the concentrations of the dissolved silicates suggest that Cm(III) complexation with the silicate dimer, Si2O2(OH)22-, may play a role.

  5. Antithrombin III: biodistribution in healthy volunteers.

    PubMed

    Knot, E A; de Jong, E; ten Cate, J W; Gie, L K; van Royen, E A

    1987-12-18

    Five healthy volunteers were injected intravenously with 73-90 uCi purified human 131I-Antithrombin III (AT III), specific biological activity 5.6 U/mg. The tracer data were analysed using a three compartment model. The plasma radioactivity half life was 66.2 +/- 1.2 (sem) h, the fractional catabolic rate constant of the plasma pool was 0.025 +/- 0.002 (sem) h-1. These data were comparable with those described in the literature. Because of the difficulty in translating the mathematical analysis of various compartments into the biological model, biodistribution was monitored by a gamma camera linked to a DEC PDP 11/34 computer system. Dynamic and static images were obtained at fixed time intervals following the injection of 131I-AT III. Whole body scanning at intervals between the time of injection (t = 0) and t = 24.5 h showed 131I-AT III distribution over the heart, lungs, liver, spleen and great vessels. Dynamic scanning was performed over the heart, spleen and liver. Overlayed frames in the first ten minutes after the 131I-AT III injection showed the following radioactivity expressed as percentage of the injected dose; 5.9% +/- 0.3 (sem) over the heart, 10.6% +/- 0.9 (sem) over the liver and 1.1% +/- 0.1 (sem) over the spleen. A slower decline of the radioactivity between t = 0 and t = 24 h; (19%) was measured over the liver compared with the radioactivity disappearance over the heart region. This shows, in combination with the fact that the radioactivity disappearance over the heart was identical with the radioactivity decline measured in the plasma samples that retention of 131I-AT III occurred in the liver.(ABSTRACT TRUNCATED AT 250 WORDS)

  6. Stellar populations of Shapley constellation III

    SciTech Connect

    Reid, N.; Mould, J.; Thompson, I.

    1987-12-01

    A V-I color-magnitude diagram is presented for a 0.6-sq deg field encompassing part of the LMC's Shapley III star-formation region. The pronounced luminosity function peak exhibited by the main-sequence stars is identified with the turnoff of the first star-forming burst, and then used as an age indicator with which to compare stellar evolutionary models with the dynamical age estimate determined by Dopita et al. (1985); the initial luminosity and mass functions are derived. The dynamical clock in Shapley III is in better agreement with the stellar evolutionary clock if models without convective overshoot are adopted. 42 references.

  7. Validation Test Report for WAVEWATCH III

    DTIC Science & Technology

    2012-11-30

    WAM and WAVEWATCH III. An experimental realtime system is now running on NAVOCEANO hardware and uses the “multi-grid” (two-way nesting) feature of...WW3, with a global grid and nine regional grids. The realtime system is validated in a limited sense using several coastal and deep- water NOAA NDBC...WAVEWATCH III Wave model Windsea Swell 73-5097-A3-5 Space & Naval Warfare Systems Command 2451 Crystal Drive Arlington, VA 22245-5200 0603207N SPAWAR ii

  8. Siderophores are not involved in Fe(III) solubilization during anaerobic Fe(III) respiration by Shewanella oneidensis MR-1.

    PubMed

    Fennessey, Christine M; Jones, Morris E; Taillefert, Martial; DiChristina, Thomas J

    2010-04-01

    Shewanella oneidensis MR-1 respires a wide range of anaerobic electron acceptors, including sparingly soluble Fe(III) oxides. In the present study, S. oneidensis was found to produce Fe(III)-solubilizing organic ligands during anaerobic Fe(III) oxide respiration, a respiratory strategy postulated to destabilize Fe(III) and produce more readily reducible soluble organic Fe(III). In-frame gene deletion mutagenesis, siderophore detection assays, and voltammetric techniques were combined to determine (i) if the Fe(III)-solubilizing organic ligands produced by S. oneidensis during anaerobic Fe(III) oxide respiration were synthesized via siderophore biosynthesis systems and (ii) if the Fe(III)-siderophore reductase was required for respiration of soluble organic Fe(III) as an anaerobic electron acceptor. Genes predicted to encode the siderophore (hydroxamate) biosynthesis system (SO3030 to SO3032), the Fe(III)-hydroxamate receptor (SO3033), and the Fe(III)-hydroxamate reductase (SO3034) were identified in the S. oneidensis genome, and corresponding in-frame gene deletion mutants were constructed. DeltaSO3031 was unable to synthesize siderophores or produce soluble organic Fe(III) during aerobic respiration yet retained the ability to solubilize and respire Fe(III) at wild-type rates during anaerobic Fe(III) oxide respiration. DeltaSO3034 retained the ability to synthesize siderophores during aerobic respiration and to solubilize and respire Fe(III) at wild-type rates during anaerobic Fe(III) oxide respiration. These findings indicate that the Fe(III)-solubilizing organic ligands produced by S. oneidensis during anaerobic Fe(III) oxide respiration are not synthesized via the hydroxamate biosynthesis system and that the Fe(III)-hydroxamate reductase is not essential for respiration of Fe(III)-citrate or Fe(III)-nitrilotriacetic acid (NTA) as an anaerobic electron acceptor.

  9. Shewanella putrefaciens produces an Fe(III)-solubilizing organic ligand during anaerobic respiration on insoluble Fe(III) oxides.

    PubMed

    Taillefert, Martial; Beckler, Jordon S; Carey, Elizabeth; Burns, Justin L; Fennessey, Christine M; DiChristina, Thomas J

    2007-11-01

    The mechanism of Fe(III) reduction was investigated using voltammetric techniques in anaerobic incubations of Shewanella putrefaciens strain 200 supplemented with Fe(III) citrate or a suite of Fe(III) oxides as terminal electron acceptor. Results indicate that organic complexes of Fe(III) are produced during the reduction of Fe(III) at rates that correlate with the reactivity of the Fe(III) phase and bacterial cell density. Anaerobic Fe(III) solubilization activity is detected with either Fe(III) oxides or Fe(III) citrate, suggesting that the organic ligand produced is strong enough to destabilize Fe(III) from soluble or solid Fe(III) substrates. Results also demonstrate that Fe(III) oxide dissolution is not controlled by the intrinsic chemical reactivity of the Fe(III) oxides. Instead, the chemical reaction between the endogenous organic ligand is only affected by the number of reactive surface sites available to S. putrefaciens. This report describes the first application of voltammetric techniques to demonstrate production of soluble organic-Fe(III) complexes by any Fe(III)-reducing microorganism and is the first report of a Fe(III)-solubilizing ligand generated by a metal-reducing member of the genus Shewanella.

  10. Effects upon metabolic pathways and energy production by Sb(III) and As(III)/Sb(III)-oxidase gene aioA in Agrobacterium tumefaciens GW4.

    PubMed

    Li, Jingxin; Yang, Birong; Shi, Manman; Yuan, Kai; Guo, Wei; Li, Mingshun; Wang, Gejiao

    2017-01-01

    Agrobacterium tumefaciens GW4 is a heterotrophic arsenite [As(III)]/antimonite [Sb(III)]-oxidizing strain. The As(III) oxidase AioAB is responsible for As(III) oxidation in the periplasm and it is also involved in Sb(III) oxidation in Agrobacterium tumefaciens 5A. In addition, Sb(III) oxidase AnoA and cellular H2O2 are also responsible for Sb(III) oxidation in strain GW4. However, the deletion of aioA increased the Sb(III) oxidation efficiency in strain GW4. In the present study, we found that the cell mobility to Sb(III), ATP and NADH contents and heat release were also increased by Sb(III) and more significantly in the aioA mutant. Proteomics and transcriptional analyses showed that proteins/genes involved in Sb(III) oxidation and resistance, stress responses, carbon metabolism, cell mobility, phosphonate and phosphinate metabolism, and amino acid and nucleotide metabolism were induced by Sb(III) and were more significantly induced in the aioA mutant. The results suggested that Sb(III) oxidation may produce energy. In addition, without periplasmic AioAB, more Sb(III) would enter bacterial cells, however, the cytoplasmic AnoA and the oxidative stress response proteins were significantly up-regulated, which may contribute to the increased Sb(III) oxidation efficiency. Moreover, the carbon metabolism was also activated to generate more energy against Sb(III) stress. The generated energy may be used in Sb transportation, DNA repair, amino acid synthesis, and cell mobility, and may be released in the form of heat.

  11. Arsenic (III, V), indium (III), and gallium (III) toxicity to zebrafish embryos using a high-throughput multi-endpoint in vivo developmental and behavioral assay.

    PubMed

    Olivares, Christopher I; Field, Jim A; Simonich, Michael; Tanguay, Robert L; Sierra-Alvarez, Reyes

    2016-04-01

    Gallium arsenide (GaAs), indium gallium arsenide (InGaAs) and other III/V materials are finding increasing application in microelectronic components. The rising demand for III/V-based products is leading to increasing generation of effluents containing ionic species of gallium, indium, and arsenic. The ecotoxicological hazard potential of these streams is unknown. While the toxicology of arsenic is comprehensive, much less is known about the effects of In(III) and Ga(III). The embryonic zebrafish was evaluated for mortality, developmental abnormalities, and photomotor response (PMR) behavior changes associated with exposure to As(III), As(V), Ga(III), and In(III). The As(III) lowest observable effect level (LOEL) for mortality was 500 μM at 24 and 120 h post fertilization (hpf). As(V) exposure was associated with significant mortality at 63 μM. The Ga(III)-citrate LOEL was 113 μM at 24 and 120 hpf. There was no association of significant mortality over the tested range of In(III)-citrate (56-900 μM) or sodium citrate (213-3400 μM) exposures. Only As(V) resulted in significant developmental abnormalities with LOEL of 500 μM. Removal of the chorion prior to As(III) and As(V) exposure was associated with increased incidence of mortality and developmental abnormality suggesting that the chorion may normally attenuate mass uptake of these metals by the embryo. Finally, As(III), As(V), and In(III) caused PMR hypoactivity (49-69% of control PMR) at 900-1000 μM. Overall, our results represent the first characterization of multidimensional toxicity effects of III/V ions in zebrafish embryos helping to fill a significant knowledge gap, particularly in Ga(III) and In(III) toxicology.

  12. Effects upon metabolic pathways and energy production by Sb(III) and As(III)/Sb(III)-oxidase gene aioA in Agrobacterium tumefaciens GW4

    PubMed Central

    Li, Jingxin; Yang, Birong; Shi, Manman; Yuan, Kai; Guo, Wei; Li, Mingshun

    2017-01-01

    Agrobacterium tumefaciens GW4 is a heterotrophic arsenite [As(III)]/antimonite [Sb(III)]-oxidizing strain. The As(III) oxidase AioAB is responsible for As(III) oxidation in the periplasm and it is also involved in Sb(III) oxidation in Agrobacterium tumefaciens 5A. In addition, Sb(III) oxidase AnoA and cellular H2O2 are also responsible for Sb(III) oxidation in strain GW4. However, the deletion of aioA increased the Sb(III) oxidation efficiency in strain GW4. In the present study, we found that the cell mobility to Sb(III), ATP and NADH contents and heat release were also increased by Sb(III) and more significantly in the aioA mutant. Proteomics and transcriptional analyses showed that proteins/genes involved in Sb(III) oxidation and resistance, stress responses, carbon metabolism, cell mobility, phosphonate and phosphinate metabolism, and amino acid and nucleotide metabolism were induced by Sb(III) and were more significantly induced in the aioA mutant. The results suggested that Sb(III) oxidation may produce energy. In addition, without periplasmic AioAB, more Sb(III) would enter bacterial cells, however, the cytoplasmic AnoA and the oxidative stress response proteins were significantly up-regulated, which may contribute to the increased Sb(III) oxidation efficiency. Moreover, the carbon metabolism was also activated to generate more energy against Sb(III) stress. The generated energy may be used in Sb transportation, DNA repair, amino acid synthesis, and cell mobility, and may be released in the form of heat. PMID:28241045

  13. Modulation of active Cr(III) complexes by bath preparation to adjust Cr(III) electrodeposition

    NASA Astrophysics Data System (ADS)

    Li, Lei; Wang, Zhi; Wang, Ming-yong; Zhang, Yi

    2013-09-01

    The preparation process of the Cr(III) bath was studied based on a perspective of accelerating the formation of active Cr(III) complexes. The results of ultraviolet-visible absorption spectroscopy (UV-Vis) and electrodeposition showed that active Cr(III) complexes in the bath prepared at room temperature in several days were rare for depositing chromium. The increase of heating temperature, time, and pH value during the bath preparation promoted the formation of active Cr(III) complexes. The chromium deposition rate increased with the concentration of active Cr(III) complexes increasing. Increasing the heating temperature from 60 to 96°C, the chromium deposition rate increased from 0.40 to 0.71 μm/min. When the concentration of active Cr(III) complexes increased, the grain size of Cr coatings increased, and the carbon content of the coating decreased. It is deduced that Cr(H2O)4(OH)L2+ (L is an organic ligand, and its valence is omitted) is a primary active Cr(III) complex.

  14. Interpreting change on the WAIS-III/WMS-III in clinical samples.

    PubMed

    Iverson, G L

    2001-02-01

    Clinicians should note that there is considerable variability in the reliabilities of the index and subtest scores derived from the third editions of the Wechsler Adult Intelligence Scale (WAIS-III) and the Wechsler Memory Scale (WMS-III). The purpose of this article is to review these reliabilities and to illustrate how they can be used to interpret change in patients' performances from test to retest. The WAIS-III IQ and Index scores are consistently the most reliable scores, in terms of both internal consistency and test-retest reliability. The most internally consistent WAIS-III subtests are Vocabulary, Information, Digit Span, Matrix Reasoning, and Arithmetic. Information and Vocabulary have the highest test-retest reliability. On the WMS-III, the Auditory Immediate Index, Immediate Memory Index, Auditory Delayed Index, and General Memory Index are the most reliable, in terms of both internal consistency and test-retest reliability. The Logical Memory I and Verbal Paired Associates I subtests are the most reliable. Data from three clinical groups (i.e., Alzheimer's disease, chronic alcohol abuse, and schizophrenia) were extracted from the Technical Manual [Psychological Corporation (1997). WAIS-III/WMS-III Technical Manual. San Antonio: Harcourt Brace] for the purpose of calculating reliable change estimates. A table of confidence intervals for test-retest measurement error is provided to help the clinician determine if patients have reliably improved or deteriorated on follow-up testing.

  15. Solvent extraction of Sc(III), Zr(IV), Th(IV), Fe(III), and Lu(III) with thiosubstituted organophosphinic acid extractants

    SciTech Connect

    Wang, C.; Li, D.

    1995-05-01

    The solvent extraction of Sc(III), Zr(IV), Th(IV), Fe(III) and Lu(III) with Cyanex 302 (bis(2,4,4-trimethylpentyl)monothiphosphinic acid) and Cyanex 301 (bis(2,4,4-trimethylpentyl)dithiophosphinic acid) in n-hexane from acidic aqueous solutions has been investigated systematically. The effect of equilibrium aqueous acidity on the extraction with these reagents was studied. The separation of Th(IV), Fe(III) and Lu(III) from Sc(III), or the separation of other metals from Lu(III) with Cyanex 302, can be achieved by controlling the aqueous acidity. However, Cyanex 301 exhibited a poor selectivity for the above metals, except for Lu(III). The extraction of these metals with Cyanex 272, Cyanex 302 and Cyanex 301 has been compared. The stripping percentages of Sc(III) for Cyanex 302 and Cyanex 301 in a single stage are near 78% and 75% with 3.5 mol/L and 5.8 mol/L sulphuric acid solutions, respectively. The effects of extractant concentration and temperature on the extraction of Sc(III) were investigated. The stoichiometry of the extraction of Sc(III) with Cyanex 302 was determined. The role of different components of Cyanex 302 in the extraction of Sc(III) was discussed. 18 refs., 10 figs.

  16. ESEA III Evaluation and Dissemination: An Assessment.

    ERIC Educational Resources Information Center

    Balyeat, Ralph R.; Norman, C. Douglas

    This study surveyed evaluation and dissemination/diffusion practices of ESEA III projects funded in the 1969 fiscal year, which projects are nearing the end of their operations as federally supported programs. The study attempted to discover if (1) the projects were evaluated in accordance with generally accepted procedures, (2) the project…

  17. Leveraging Information Technology. Track III: Organizational Issues.

    ERIC Educational Resources Information Center

    CAUSE, Boulder, CO.

    Seven papers from the 1987 CAUSE conference's Track III, Organizational Issues, are presented. They include: "Learning Resources and Technologies: A Unified Organizational Reorientation to Administering Educational Support Services" (Morrell D. Boone); "IRM: A Short-Lived Concept?" (James I. Penrod and Michael G. Dolence);…

  18. Sex Bias, Diagnosis, and DSM-III.

    ERIC Educational Resources Information Center

    Hamilton, Sandra; And Others

    1986-01-01

    Sixty-five clinical psycholgists independently diagnosed 18 written case histories on the basis of 110 DSM-III categories. Females were rated significantly more histrionic than males exhibiting identical histrionic symptoms, but males were not rated as more antisocial than females. The findings suggest that vague diagnostic descriptions promote…

  19. International Space Programs. Aerospace Education III.

    ERIC Educational Resources Information Center

    Air Univ., Maxwell AFB, AL. Junior Reserve Office Training Corps.

    This curriculum guide is prepared for the Aerospace Education III series publication entitled "International Space Programs." The guide is organized according to specific chapters in the textbook. It provides guidelines for teachers in terms of objectives, behavioral objectives, suggested outlines, orientation, suggested key points,…

  20. Constraining the Statistics of Population III Binaries

    NASA Technical Reports Server (NTRS)

    Stacy, Athena; Bromm, Volker

    2012-01-01

    We perform a cosmological simulation in order to model the growth and evolution of Population III (Pop III) stellar systems in a range of host minihalo environments. A Pop III multiple system forms in each of the ten minihaloes, and the overall mass function is top-heavy compared to the currently observed initial mass function in the Milky Way. Using a sink particle to represent each growing protostar, we examine the binary characteristics of the multiple systems, resolving orbits on scales as small as 20 AU. We find a binary fraction of approx. 36, with semi-major axes as large as 3000 AU. The distribution of orbital periods is slightly peaked at approx. < 900 yr, while the distribution of mass ratios is relatively flat. Of all sink particles formed within the ten minihaloes, approx. 50 are lost to mergers with larger sinks, and 50 of the remaining sinks are ejected from their star-forming disks. The large binary fraction may have important implications for Pop III evolution and nucleosynthesis, as well as the final fate of the first stars.

  1. International Space Programs. Aerospace Education III.

    ERIC Educational Resources Information Center

    Bulmer, S. B.

    This book, one in the series on Aerospace Education III, is a collection of the diverse information available regarding the international space programs. The five goals listed for the book are: to examine the Soviet space program, to understand the future of Soviet space activity, to examine other national and international space programs, to…

  2. Academic Achievement of NCAA Division III Athletes

    ERIC Educational Resources Information Center

    Barlow, Kathy A.; Hickey, Ann

    2014-01-01

    A study of 215 athletes at a small private liberal arts Division III college revealed that athletes (a) begin their college experience with SATs no different from non-athletes; (b) attain GPAs that do not significantly differ from those of nonathletes; (c) achieve GPAs that do not significantly differ between their "in-season" semester…

  3. Photodetectors using III-V nitrides

    DOEpatents

    Moustakas, T.D.

    1998-12-08

    A bandpass photodetector using a III-V nitride and having predetermined electrical properties is disclosed. The bandpass photodetector detects electromagnetic radiation between a lower transition wavelength and an upper transition wavelength. That detector comprises two low pass photodetectors. The response of the two low pass photodetectors is subtracted to yield a response signal. 24 figs.

  4. Photodetectors using III-V nitrides

    DOEpatents

    Moustakas, Theodore D.

    1998-01-01

    A bandpass photodetector using a III-V nitride and having predetermined electrical properties. The bandpass photodetector detects electromagnetic radiation between a lower transition wavelength and an upper transition wavelength. That detector comprises two low pass photodetectors. The response of the two low pass photodetectors is subtracted to yield a response signal.

  5. The Zeplin-Iii Veto Detector

    NASA Astrophysics Data System (ADS)

    Scovell, P. R.

    2010-12-01

    An active veto detector to complement the ZEPLIN-III two phase Xenon, direct dark matter device is described. The design consists of 52 plastic scintillator segments, individually read out by high efficiency photomultipliers, coupled to a Gd loaded passive polypropylene shield. Experimental work was performed to determine the plastic scintillator characteristics which were used to inform a complete end-to-end Monte Carlo simulation of the expected performance of the new instrument, both operating alone and as an active veto detector for ZEPLIN-III. The veto device will be capable of tagging over 65% of expected coincident nuclear recoil events in the energy range of interest in ZEPLIN-III, and over 14% for gamma ray rejection (gamma and neutron rate is predicted by simulation), while contributing no significant additional background. In addition it will also provide valuable diagnostic capabilities. The inclusion of the veto to ZEPLIN-III will aid to significantly improve the sensitivity to spin independent WIMP-nucleon cross sections 10-9 pb.

  6. Modelling the arsenic (V) and (III) adsorption

    NASA Astrophysics Data System (ADS)

    Rau, I.; Meghea, A.; Peleanu, I.; Gonzalo, A.; Valiente, M.; Zaharescu, M.

    2003-01-01

    Arsenic has gained great notoriety historically for its toxic properties. In aquatic environment, arsenic can exist in several oxidation states, as both inorganic and organometallic species. As (V) is less toxic than As (III). Most research has been directed to the control of arsenic pollution of potable water. Various techniques such as precipitation with iron and aluminium hydroxides, ion exchange, reverse osmosis, and adsorption are used for As (V) removal from surface and waste waters. Because of the easy handling of sludge, its free operation and regeneration capability, the adsorption technique has secured a place as one of the advanced methods of arsenic removal. A study of As (III) and As (V) sorption onto some different adsorbents (Fe (III) — iminodiacetate resin, nanocomposite materials, Fe(III) — forager sponge) referring to kinetic considerations and modelling of the process will be presented. All the systems studied are better described by Freundlich-Langmuir isotherm and the rate constant evaluation shows a sub-unitary order for the adsorption process.

  7. Kenston Aerospace: Title III ESEA Project.

    ERIC Educational Resources Information Center

    Kenston Local School District, Chagrin Falls, OH.

    The objectives of a three-year comprehensive aerospace education program at Kenston High School, Chagrin Falls, Ohio, funded under Title III ESEA, were to provide marketable skills for non-College-bound students as well as counseling for the student planning on college or technical school education in the aviation field. Students also were taught…

  8. FutureTox III: Bridges for Translation

    EPA Science Inventory

    The present document describes key discussion points and outcomes of a Society of Toxicology (SOT) Contemporary Concepts in Toxicology (CCT) Workshop, entitled FutureTox III1,2 that was held in Crystal City, Virginia, November 19-20, 2015. The workshop built on the many lessons l...

  9. Gold(III)-Catalyzed Hydration of Phenylacetylene

    ERIC Educational Resources Information Center

    Leslie, J. Michelle; Tzeel, Benjamin A.

    2016-01-01

    A guided inquiry-based experiment exploring the regioselectivity of the hydration of phenylacetylene is described. The experiment uses an acidic gold(III) catalyst in a benign methanol/water solvent system to introduce students to alkyne chemistry and key principles of green chemistry. The experiment can be easily completed in approximately 2 h,…

  10. Maggie III: The Prototypical Library System.

    ERIC Educational Resources Information Center

    Dowlin, Kenneth E.; And Others

    1986-01-01

    Describes the Maggie III automated library system, which supports a public access catalog, cataloging interface, bibliographic maintenance, circulation, electronic mail, and community information databases, with acquisitions and serials modules planned. Sidebars describe the community information database's structure, planned use of software by…

  11. Exploring Flipped Classroom Instruction in Calculus III

    ERIC Educational Resources Information Center

    Wasserman, Nicholas H.; Quint, Christa; Norris, Scott A.; Carr, Thomas

    2017-01-01

    In an undergraduate Calculus III class, we explore the effect of "flipping" the instructional delivery of content on both student performance and student perceptions. Two instructors collaborated to determine daily lecture notes, assigned the same homework problems, and gave identical exams; however, compared to a more traditional…

  12. The Changing Nature of Division III Athletics

    ERIC Educational Resources Information Center

    Beaver, William

    2014-01-01

    Non-selective Division III institutions often face challenges in meeting their enrollment goals. To ensure their continued viability, these schools recruit large numbers of student athletes. As a result, when compared to FBS (Football Bowl Division) institutions these schools have a much higher percentage of student athletes on campus and a…

  13. Cosmological Impact of Population III Binaries

    NASA Astrophysics Data System (ADS)

    Chen, Ke-Jung; Bromm, Volker; Heger, Alexander; Jeon, Myoungwon; Woosley, Stan

    2015-03-01

    We present the results of the stellar feedback from Population III (Pop III) binaries by employing improved, more realistic Pop III evolutionary stellar models. To facilitate a meaningful comparison, we consider a fixed mass of 60 {{M}⊙ } incorporated in Pop III stars, either contained in a single star, or split up in binary stars of 30 {{M}⊙ } each or an asymmetric case of one 45 and one 15 {{M}⊙ } star. Whereas the sizes of the resulting H ii regions are comparable across all cases, the He iii regions around binary stars are significantly smaller than that of the single star. Consequently, the He+ 1640 \\overset{\\circ}A recombination line is expected to become much weaker. Supernova (SN) feedback exhibits great variety due to the uncertainty in possible explosion pathways. If at least one of the component stars dies as a hypernova about 10 times more energetic than conventional core-collapse SNe, the gas inside the host minihalo is effectively blown out, chemically enriching the intergalactic medium (IGM) to an average metallicity of {{10}-4}-{{10}-3} {{Z}⊙ }, out to ˜ 2 kpc. The single star, however, is more likely to collapse into a black hole, accompanied by at most very weak explosions. The effectiveness of early chemical enrichment would thus be significantly reduced, in contrast to the lower mass binary stars, where at least one component is likely to contribute to heavy element production and dispersal. Important new feedback physics is also introduced if close binaries can form high-mass X-ray binaries, leading to the pre-heating and -ionization of the IGM beyond the extent of the stellar H ii regions.

  14. Inhibition of HTLV-III by exogenous oligonucleotides

    SciTech Connect

    Goodchild, J.; Zamecnik, P.C.

    1989-02-21

    A method is described of detecting the presence of HTLV-III virus in a sample by demonstrating inhibition of replication of the virus in cells which are normally killed by the HTLV-III virus after the cells have been (a) combined with the sample and an oligonucleotide complementary to at least one highly conserved region of the HTLV-III genome necessary for HTLV-III replication and capable of hybridizing with at least the highly conserved region, the highly conserved region of the HTLV-III genome being a nucleotide sequence present in the genomes of HTLV-III isolates and the oligonucleotide complementary to at least one highly conserved region of the HTLV-III genome necessary for HTLV-III replication being complementary to a region of the HTLV-III genome.

  15. LM1500 Engine Marinization Contract. Phase III. Materials and Processes Development for Phase III Engine Components.

    DTIC Science & Technology

    The purpose of this report is to briefly document the principal difficulties encountered and the solutions which were effected in the course of manufacturing the modified Phase III test engine hardware. (Author)

  16. Theoretical insights into the separation of Am(III) over Eu(III) with PhenBHPPA.

    PubMed

    Wu, Han; Wu, Qun-Yan; Wang, Cong-Zhi; Lan, Jian-Hui; Liu, Zhi-Rong; Chai, Zhi-Fang; Shi, Wei-Qun

    2015-10-14

    Due to the similar chemical properties of actinides An(iii) and lanthanides Ln(iii), their separation in spent nuclear fuel reprocessing is extremely challenging. A 1,10-phenanthroline dipicolinamide-based ligand (PhenBHPPA) has been identified to possess a selectivity for Am(iii) over Eu(iii) and could potentially be used for group actinide extraction. In this study, quasi-relativistic density functional theoretical calculations have been used to disclose the interaction mechanisms of Am(iii) and Eu(iii) complexes with PhenBHPPA. The electronic structures, bonding nature, QTAIM (Quantum Theory of Atoms in Molecules) analyses and thermodynamic behaviors of the Am(iii) and Eu(iii) complexes with PhenBHPPA have been explored in detail. According to the Wiberg bond indices (WBIs) and QTAIM analyses, interactions between the ligand and metal cations (Am(iii) and Eu(iii)) exhibit a weakly covalent character. Thermodynamic analyses show that the charged complexes [ML(NO3)2](+) appear to be the most stable species in the complexation processes. Moreover, it is more energetically favorable for PhenBHPPA to bind to Am(iii) compared to Eu(iii). Our study could render new insights into understanding the selectivity of the ligand towards minor actinides and the separation of An(iii) from Ln(iii) via liquid-liquid extraction.

  17. The Behavior of Thallium(III) During Jarosite Precipitation

    SciTech Connect

    Dutrizac,J.; Chen, T.; Beauchemin, S.

    2005-01-01

    The behavior of thallium(III) under the general conditions employed for jarosite precipitation in the zinc industry was investigated in a series of laboratory experiments. Thallium(III) does not appear to form end-member jarosite-type compounds, MTl{sub 3}(SO{sub 4}){sub 2}(OH){sub 6}, where M is Na, K, NH{sub 4}, etc. In acid solutions at pH > 0.7, the thallium(III) hydrolyzes to Tl{sub 2}O{sub 3}; in more strongly acid media, two K-Tl(III) sulphate phases crystallize at temperatures < 90 C. The K-Tl(III) sulphate phases were investigated by chemical and X-ray diffraction analyses and by thermogravimetry. Although end-member Tl(III) analogues of jarosite-type compounds could not be synthesized, it is possible to incorporate significant amounts of Tl(III) in potassium jarosite (KFe3(SO4)2(OH)6), and over 20 at.% substitution of Tl(III) for Fe(III) was achieved. The presence of Tl(III) in the potassium jarosite structure was confirmed by microscopic methods, electron microprobe analyses and X-ray absorption near-edge structure (XANES) spectroscopy. The Tl(III)-bearing species forms rapidly, and excess Fe(III) precipitates as nearly Tl-free potassium jarosite which envelops the initially formed Tl(III)-bearing potassium jarosite phase.

  18. Coronal type III radio bursts and their X-ray flare and interplanetary type III counterparts

    NASA Astrophysics Data System (ADS)

    Reid, Hamish A. S.; Vilmer, Nicole

    2017-01-01

    Context. Type III bursts and hard X-rays are both produced by flare energetic electron beams. The link between both emissions has been investigated in many previous studies, but no statistical studies have compared both coronal and interplanetary type III bursts with X-ray flares. Aims: Using events where the coronal radio emission above 100 MHz is exclusively from type III bursts, we revisited some long-standing questions regarding the relation between type III bursts and X-ray flares: Do all coronal type III bursts have X-ray counterparts? What correlation, if any, occurs between radio and X-ray intensities? What X-ray and radio signatures above 100 MHz occur in connection with interplanetary type III bursts below 14 MHz? Methods: We analysed ten years of data from 2002 to 2011 starting with a selection of coronal type III bursts above 100 MHz. We used X-ray flare information from RHESSI >6 keV to make a list of 321 events that have associated type III bursts and X-ray flares, encompassing at least 28% of the initial sample of type III events. We then examined the timings, intensities, associated GOES class, and whether there was an associated interplanetary radio signature in both radio and X-rays. Results: For our 321 events with radio and X-ray signatures, the X-ray emission at 6 keV usually lasted much longer than the groups of type III bursts at frequencies >100 MHz. The selected events were mostly associated with GOES B and C class flares. A weak correlation was found between the type III radio flux at frequencies below 327 MHz and the X-ray intensity at 25-50 keV, with an absence of events at high X-ray intensity and low type III radio flux. The weakness of the correlation is related to the coherent emission mechanism of radio type IIIs which can produce high radio fluxes by low density electron beams. Interplanetary type III bursts (<4 MHz) were observed for 54% of the events. The percentage of association increased when events were observed with 25-50 ke

  19. Luminescence of europium (III) complexes for visualization

    NASA Astrophysics Data System (ADS)

    Kolontaeva, Olga A.; Pozharov, Mikhail V.; Korolovich, Vladimir F.; Khokhlova, Anastasia R.; Kirdyanova, Anna N.; Burmistrova, Natalia A.; Zakharova, Tamara V.; Goryacheva, Irina Y.

    2016-04-01

    With the purpose to develop bright non-toxic luminescent label for theranostic application we have studied complexation of lanthanide dipicolinates (2,6-pyridinedicarboxylates) by sodium alginate and effect of thermal exposure of synthesized micro-capsules on their luminescent properties. Synthesized micro-capsules are stable in acidic medium but dissolve at pH ~ 4 due to transformation of cationic europium dipicolinate complex to anionic. Luminescence studies have shown that emission spectra of europium(III)-alginate complexes (both chloride and dipicolinate) contain two intensive bands characteristic to Eu3+ ion (5D0 --> 7F1 (590 nm) and 5D0 --> 7F1 (612 nm)). We have also found that at 160ºC europium(III)- alginate micro-capsules decompose to black, soot-like substance, therefore, their thermal treatment must be performed in closed environment (i.e., sealed ampoules).

  20. Flexor tendon repair in zone III.

    PubMed

    Al-Qattan, Mohammad M

    2011-01-01

    There is a paucity of the literature on the outcome of zone III flexor tendon injuries. In this paper, we report on the results of zone III flexor tendon repair in 35 consecutive adult patients with clean cut lacerations of both flexor tendons in 42 fingers. There were 25 men and 10 women with an average age of 32 years. Repair of both flexor tendons was performed using 'figure of eight' core sutures and a continuous epitendinous suture. Postoperatively, an immediate active range of motion protocol was applied to ensure full active extension of the interphalangeal joints. The results were assessed using the Strickland-Glogovac grading system. There were no ruptures. One patient with two injured fingers developed complex regional pain syndrome and the final outcome was fair in both fingers. In the remaining 34 patients (40 fingers), 33 patients (38 fingers) had an excellent outcome and the remaining patient (two fingers) had a good outcome.

  1. Iron (III) chloride doping of CVD graphene.

    PubMed

    Song, Yi; Fang, Wenjing; Hsu, Allen L; Kong, Jing

    2014-10-03

    Chemical doping has been shown as an effective method of reducing the sheet resistance of graphene. We present the results of our investigations into doping large area chemical vapor deposition graphene using Iron (III) Chloride (FeCl(3)). It is shown that evaporating FeCl(3) can increase the carrier concentration of monolayer graphene to greater than 10(14) cm(-2) and achieve resistances as low as 72 Ω sq(-1). We also evaluate other important properties of the doped graphene such as surface cleanliness, air stability, and solvent stability. Furthermore, we compare FeCl(3) to three other common dopants: Gold (III) Chloride (AuCl(3)), Nitric Acid (HNO(3)), and TFSA ((CF(3)SO(2))(2)NH). We show that compared to these dopants, FeCl(3) can not only achieve better sheet resistance but also has other key advantages including better solvent stability.

  2. LSPRAY-III: A Lagrangian Spray Module

    NASA Technical Reports Server (NTRS)

    Raju, M. S.

    2008-01-01

    LSPRAY-III is a Lagrangian spray solver developed for application with parallel computing and unstructured grids. It is designed to be massively parallel and could easily be coupled with any existing gas-phase flow and/or Monte Carlo Probability Density Function (PDF) solvers. The solver accommodates the use of an unstructured mesh with mixed elements of either triangular, quadrilateral, and/or tetrahedral type for the gas flow grid representation. It is mainly designed to predict the flow, thermal and transport properties of a rapidly vaporizing spray because of its importance in aerospace application. The manual provides the user with an understanding of various models involved in the spray formulation, its code structure and solution algorithm, and various other issues related to parallelization and its coupling with other solvers. With the development of LSPRAY-III, we have advanced the state-of-the-art in spray computations in several important ways.

  3. FutureTox III: Bridges for Translation.

    PubMed

    Juberg, Daland R; Knudsen, Thomas B; Sander, Miriam; Beck, Nancy B; Faustman, Elaine M; Mendrick, Donna L; Fowle, John R; Hartung, Thomas; Tice, Raymond R; Lemazurier, Emmanuel; Becker, Richard A; Fitzpatrick, Suzanne Compton; Daston, George P; Harrill, Alison; Hines, Ronald N; Keller, Douglas A; Lipscomb, John C; Watson, David; Bahadori, Tina; Crofton, Kevin M

    2017-01-01

    Future Tox III, a Society of Toxicology Contemporary Concepts in Toxicology workshop, was held in November 2015. Building upon Future Tox I and II, Future Tox III was focused on developing the high throughput risk assessment paradigm and taking the science of in vitro data and in silico models forward to explore the question-what progress is being made to address challenges in implementing the emerging big-data toolbox for risk assessment and regulatory decision-making. This article reports on the outcome of the workshop including 2 examples of where advancements in predictive toxicology approaches are being applied within Federal agencies, where opportunities remain within the exposome and AOP domains, and how collectively the toxicology community across multiple sectors can continue to bridge the translation from historical approaches to Tox21 implementation relative to risk assessment and regulatory decision-making.

  4. Background investigation in EDELWEISS-III

    SciTech Connect

    Scorza, Silvia

    2015-08-17

    Protection from and rejection of backgrounds is a key issue for the EDELWEISS-III direct dark matter detection experiment which aims at exploring the 10{sup −9} pb cross-section region for spin-independent WIMP-nucleon interaction. The detector is located in the low radioactivity environment of the Modane Underground Laboratory and consists of 36 advanced FID germanium detectors operating at 18 mK in a dilution refrigerator in order to identify eventual rare nuclear recoils induced by elastic scattering of WIMPs from our Galactic halo. I will discuss the background and the methods of rejecting it with the FID detectors. Detector performances and the first analysis of data acquired in a long-term campaign will be presented as well. The FID detector technology is not limited to EDELWEISS-III but can further be employed in the next generation of cryogenic detector experiments.

  5. BES-III distributed computing status

    NASA Astrophysics Data System (ADS)

    Belov, S. D.; Deng, Z. Y.; Korenkov, V. V.; Li, W. D.; Lin, T.; Ma, Z. T.; Nicholson, C.; Pelevanyuk, I. S.; Suo, B.; Trofimov, V. V.; Tsaregorodtsev, A. U.; Uzhinskiy, A. V.; Yan, T.; Yan, X. F.; Zhang, X. M.; Zhemchugov, A. S.

    2016-09-01

    The BES-III experiment at the Institute of High Energy Physics (Beijing, China) is aimed at the precision measurements in e+e- annihilation in the energy range from 2.0 till 4.6 GeV. The world's largest samples of J/psi and psi' events and unique samples of XYZ data have been already collected. The expected increase of the data volume in the coming years required a significant evolution of the computing model, namely shift from a centralized data processing to a distributed one. This report summarizes a current design of the BES-III distributed computing system, some of key decisions and experience gained during 2 years of operations.

  6. Gold(III) complexes in medicinal chemistry.

    PubMed

    Maia, Pedro Ivo da Silva; Deflon, Victor M; Abram, Ulrich

    2014-09-01

    A number of gold(III) compounds has been designed with the objective of overcoming the disadvantages associated with the platinum-based drugs for cancer treatment. Compounds of a remarkable structural manifold show significant antiproliferative effects in vitro against a number of cancer cells, including cisplatin resistant ones. The target of most of them is, unlike that of cisplatin, not the DNA. Although the mechanisms of action displayed by the gold compounds in biological media are still under investigation, many studies show evidence that the cellular targets are mitochondria-based. Recent advances in gold(III) medicinal chemistry also recommend such compounds for other pharmacological applications such as the treatment of viral or parasitic diseases. The radioactive isotopes (198)Au and (199)Au present potential in radiotherapy.

  7. Co(II)4, Co(II)7, and a Series of Co(II)2Ln(III) (Ln(III) = Nd(III), Sm(III), Gd(III), Tb(III), Dy(III)) Coordination Clusters: Search for Single Molecule Magnets.

    PubMed

    Modak, Ritwik; Sikdar, Yeasin; Thuijs, Annaliese E; Christou, George; Goswami, Sanchita

    2016-10-03

    We report herein the syntheses and investigation of the magnetic properties of a Co(II)4 compound, a series of trinuclear Co(II)2Ln(III) (Ln(III) = Nd(III), Sm(III), Gd(III), Tb(III), Dy(III)) complexes, and a Co(II)7 complex. The homometallic Co(II)4 core was obtained from the reaction of Ln(NO3)3·xH2O/Co(NO3)2·6H2O/H2vab/Et3N in a 0.5:0.5:1:2 ratio in methanol. Variation in synthetic conditions was necessary to get the desired Co(II)-Ln(III) complexes. The Co(II)-Ln(III) assembly was synthesized from Ln(NO3)3·xH2O/Co(OAc)2·4H2O/H2vab/NaOMe in a 0.4:0.5:1:1 ratio in methanol. The isostructural Co(II)2Ln(III) complexes have a core structure with the general formula [Co2Ln(Hvab)4(NO3)](NO3)2·MeOH·H2O, (where H2vab = 2-[(2-hydroxymethyl-phenylimino)-methyl]-6-methoxy-phenol) with simultaneous crystallization of Co(II)7 complex in each reaction. The magnetic investigation of these complexes reveals that both homometallic complexes and four Co(II)-Ln(III) complexes (except Co(II)-Nd(III)) display behavior characteristic of single molecule magnets.

  8. [Role of antithrombin iii in cardiac surgery].

    PubMed

    Muedra, V; Barettino, D; D'Ocón, P

    2013-11-01

    Coagulation of blood is of multidisciplinary interest. Cardiac surgery produces major changes in the delicate balance between pro-and anti-coagulant serum factors. The role of antithrombin iii has been analysed after finding evidence that associated decreased levels of protein activity to postoperative morbidity and mortality. Supplementing exogenous antithrombin is considered with the aim of optimising outcomes. Its intrinsic anticoagulant and anti-inflammatory properties have stimulated a growing interest, and suggests new lines of research.

  9. Type III-B rotaxane dendrimers.

    PubMed

    Ho, Watson K-W; Lee, Siu-Fung; Wong, Chi-Hin; Zhu, Xiao-Ming; Kwan, Chak-Shing; Chak, Chun-Pong; Mendes, Paula M; Cheng, Christopher H K; Leung, Ken Cham-Fai

    2013-11-28

    Type III-B first generation [3]rotaxane and second generation [4]rotaxane dendrimers have been synthesized via (1) a modified copper-catalyzed alkyne-azide cycloaddition (CuAAC), (2) Glaser-Hay's acetylenic oxidative homo-coupling, and (3) amide formation. The dendron does not reveal obvious cytotoxicities in L929 fibroblast cells. The rotaxane dendrimers can capture ammonia and are switchable both in solution and on surfaces.

  10. Doublet III: status and future plans

    SciTech Connect

    Rawls, J.M.

    1980-04-01

    A synopsis is presented of the experimental results from the ohmic heating phase of Doublet III, with emphasis on the production of good target plasmas for the upcoming neutral beam injection phase. The program plan for the device over the life of the US-Japan cooperative program is discussed, as is the status of the preliminary investigation into replacing the present vacuum vessel by one better suited for ETF simulation.

  11. Addendum I, BIOPLUME III Graphics Conversion to SURFER Format

    EPA Pesticide Factsheets

    This procedure can be used to create a SURFER® compatible grid file from Bioplume III input and output graphics. The input data and results from Bioplume III can be contoured and printed directly from SURFER.

  12. The nuclear magnetic resonance spectra of bisphthalocyaninatolanthanide (III). Interim report

    SciTech Connect

    Tsutsui, M.; Kasuga, K.

    1980-06-01

    The NMR spectra of bisphthalocyaninatolanthanide (III) complexes (La, Nd, Sm, and Eu) have been examined. An effect of a macrocyclic-ring current and induced shift caused by lanthanide (III) ions were discussed.

  13. III-nitride-based avalanche photo detectors

    NASA Astrophysics Data System (ADS)

    McClintock, Ryan; Cicek, Erdem; Vashaei, Zahra; Bayram, Can; Razeghi, Manijeh; Ulmer, Melville P.

    2010-08-01

    Research into III-Nitride based avalanche photodiodes (APDs) is motivated by the need for high sensitivity ultraviolet (UV) detectors in numerous civilian and military applications. By designing III-Nitride photodetectors that utilize low-noise impact ionization high internal gain can be realized-GaN APDs operating in Geiger mode can achieve gains exceeding 1×107. Thus with careful design, it becomes possible to count photons at the single photon level. In this paper we review the current state of the art in III-Nitride visible-blind APDs and discuss the critical design choices necessary to achieve high performance Geiger mode devices. Other major technical issues associated with the realization of visible-blind Geiger mode APDs are also discussed in detail and future prospects for improving upon the performance of these devices are outlined. The photon detection efficiency, dark count rate, and spectral response of or most recent Geiger-mode GaN APDs on free-standing GaN substrates are studied under low photon fluxes, with single photon detection capabilities being demonstrated. We also present our latest results regarding linear mode gain uniformity: the study of gain uniformity helps reveal the spatial origins of gain so that we can better understand the role of defects.

  14. An octanuclear iron(III) isobutyrate wheel.

    PubMed

    Baca, Svetlana G; Breukers, Stefanie; Ellern, Arkady; Kögerler, Paul

    2011-12-01

    The reaction of the μ(3)-oxido-centred trinuclear isobutyrate cluster [Fe(3)O(O(2)CCHMe(2))(6)(H(2)O)(3)](+) with an excess of phenol (PhOH) in chloroform produces a novel octanuclear Fe(III) cluster, cyclo-tetra-μ(2)-hydroxido-dodeca-μ(2)-isobutyrato-κ(24)O:O'-octa-μ(2)-phenolato-κ(16)O:O'-octairon(III) phenol hexasolvate monohydrate, [Fe(8)(C(4)H(7)O(2))(12)(C(6)H(5)O)(8)(OH)(4)]·6C(6)H(5)OH·H(2)O. The neutral cluster is located about a centre of inversion and consists of a planar ring of eight Fe(III) centres with two types of bridges between adjacent Fe atoms: each Fe atom is bridged to one of its neighbours by a μ-hydroxide and two 1,3-bridging carboxylates, or by two phenolate and one 1,3-bridging isobutyrate ligand. The cavity within the {Fe(8)} wheel is occupied by a disordered water molecule. Intermolecular O-H···O hydrogen bonds and C-H···π interactions connect the clusters and the phenol solvent molecules to form a three-dimensional network.

  15. 1,2,4-Diazaphospholide complexes of lanthanum(iii), cerium(iii), neodymium(iii), praseodymium(iii), and samarium(iii): synthesis, X-ray structural characterization, and magnetic susceptibility studies.

    PubMed

    Zhao, Minggang; Wang, Lixia; Li, Pangpang; Ma, Jianping; Zheng, Wenjun

    2016-07-05

    A few heteroleptic, charge-separated heterobimetallic, and polymeric alkali metalate complexes of 1,2,4-diazaphospholide lanthanum(iii), cerium(iii), neodymium(iii), praseodymium(iii), and samarium(iii) were simply prepared via the metathesis reaction of MCl3 (THF)m (m = 1-2) and K[3,5-R2dp] ([3,5-R2dp](-) = 3,5-di-substituent-1,2,4-diazaphospholide; R = tBu, Ph) in a varied ratio (1 : 3, 1 : 4, and 1 : 5, respectively) at room temperature in tetrahydrofuran. All the complexes were fully characterized by (1)H, (13)C{(1)H}, (31)P{(1)H}, IR, and X-ray single crystal diffraction analysis despite their paramagnetism (excluding La(iii) complexes). The structures of the complexes were found to feature varied coordination modes. The magnetic properties of several compounds were studied by magnetic susceptibility, and the complexes presented the magnetic moments close to or lower than the theoretical values for the free ions in the trivalent oxidation states (Pr(3+), Nd(3+)).

  16. A newly developed chromium(III) gel technology

    SciTech Connect

    Sydansk, R.D. . Research Div.)

    1990-08-01

    Laboratory testing of a recently developed chromium(III) (Cr(III)) gel technology is reported. The gels can be used in conjunction with a number of oilfield treatments. The single-fluid acrylamide-polymer/Cr(III)-carboxylate aqueous gels are formed by crosslinking acrylamide polymer with a Cr(III)-carboxylate-complex crosslinking agent. Representative gel compositions and associated gel properties are discussed.

  17. The Structure of Bis(phthalocyaninato)neodymium(III).

    DTIC Science & Technology

    1980-06-01

    synthesis of lanthanide (III) phthalocyanine complexes 1 was established by Kirin and Moskalev, many studies on their composi- 2 tions and properties have...been reported. For instance, intense attention has been directed toward electrochromism of bis(phthalocyaninato) lanthanide (III) complexes , Pc2Ln(III)H...The structural analysis of bis(phthalocyaninato) lanthanide (III) complexes would provide useful information to investigate their electo- chromuism, and

  18. Comparative Studies on Periodatocuprate(II, III) and Telluratocuprate(II, III)

    NASA Astrophysics Data System (ADS)

    Mingmei, Wu; Qiang, Su; Gang, Hu; Yufang, Ren

    1995-02-01

    The crystal structures, electronic spectra, and Cu2 p XPS of Cu(III) complexes Na 4H[Cu(H 2TeO 6) 2] · 17H 2O and Na 4K[Cu (HIO 6) 2] · 12H2O have been described. The characterizations of a Cu(III) atom in a complex are as follows: (i) In a square-planar coordination, the average bond length of Cu-O is 0.183 nm, shorter than the 0.190-0.200 nm found for a Cu(II) complex. (2) The "blue shift" occurs for d-d transitions in the electronic spectrum of the Cu(III) complex compared to those of its related Cu(II) complex, resulting from the higher valence state. (3) Cu(III) compounds with CuO 4 square-planar coordination are expected to be diamagnetic whereas Cu(II) compounds to be paramagnetic. (4) Comprehensive investigations on Cu2 p XPS show that the binding energy of Cu2 p3/2 of a pure Cu(III) compound is about 2.0 eV higher than that of its corresponding Cu(II) compound: the shakeup satellites do not appear in the Cu2 p XPS for a pure diamagnetic Cu(III) compound, the same as found for a diamagnetic Ni(II) compound: the FWHM of the signal of Cu2 p XPS may become broader for Cu(III) compound because its core hole's lifetime shortens due to the higher valence state of copper.

  19. Brazilian Adaptation of the Woodcock-Johnson III Cognitive Tests

    ERIC Educational Resources Information Center

    Wechsler, Solange Muglia; Nunes, Carlos Sancineto; Schelini, Patricia Waltz; Pasian, Sonia Regina; Homsi, Silvia Vertoni; Moretti, Lucia; Anache, Alexandra Ayach

    2010-01-01

    An adaptation of the standard battery of Woodcock-Johnson III Tests of Cognitive Abilities (WJ-III) for Brazilian children and youth was investigated. The sample was composed of 1094 students (54 percent girls), ages 7-17, living in Sao Paulo state (91 percent). Items from Brazilian school books as well as from the WJ-III Spanish version…

  20. 49 CFR 172.440 - RADIOACTIVE YELLOW-III label.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 2 2013-10-01 2013-10-01 false RADIOACTIVE YELLOW-III label. 172.440 Section 172... REQUIREMENTS, AND SECURITY PLANS Labeling § 172.440 RADIOACTIVE YELLOW-III label. (a) Except for size and color, the RADIOACTIVE YELLOW-III label must be as follows: EC02MR91.034 (b) In addition to complying...

  1. 49 CFR 172.440 - RADIOACTIVE YELLOW-III label.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 2 2014-10-01 2014-10-01 false RADIOACTIVE YELLOW-III label. 172.440 Section 172... REQUIREMENTS, AND SECURITY PLANS Labeling § 172.440 RADIOACTIVE YELLOW-III label. (a) Except for size and color, the RADIOACTIVE YELLOW-III label must be as follows: EC02MR91.034 (b) In addition to complying...

  2. 49 CFR 172.440 - RADIOACTIVE YELLOW-III label.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 2 2012-10-01 2012-10-01 false RADIOACTIVE YELLOW-III label. 172.440 Section 172... REQUIREMENTS, AND SECURITY PLANS Labeling § 172.440 RADIOACTIVE YELLOW-III label. (a) Except for size and color, the RADIOACTIVE YELLOW-III label must be as follows: EC02MR91.034 (b) In addition to complying...

  3. 49 CFR 172.440 - RADIOACTIVE YELLOW-III label.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 2 2011-10-01 2011-10-01 false RADIOACTIVE YELLOW-III label. 172.440 Section 172... REQUIREMENTS, AND SECURITY PLANS Labeling § 172.440 RADIOACTIVE YELLOW-III label. (a) Except for size and color, the RADIOACTIVE YELLOW-III label must be as follows: EC02MR91.034 (b) In addition to complying...

  4. Teaching a Course on World War III: An Introductory Approach.

    ERIC Educational Resources Information Center

    Sussman, Glenn

    1987-01-01

    Provides a description of an upper division college course on nuclear war. The course, which used an interdisciplinary approach and many resource speakers, was divided into three components: the consequences of World War III, the causes of World War III, and the prevention of World War III. Includes a detailed course outline along with required…

  5. Microbial As(III) Oxidation in Water Treatment Plant Filters

    EPA Science Inventory

    Arsenic exists in two oxidation states in water - arsenite [As(III)] and arsenate [As(V)]. As(III) is relatively mobile in water and difficult to remove by arsenic-removal treatment processes. Source waters that contain As(III) must add a strong oxidant such as free chlorine or p...

  6. 75 FR 14575 - Voting Equipment Evaluations Phase III

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-26

    ... National Institute of Standards and Technology Voting Equipment Evaluations Phase III AGENCY: National... Phase III of the benchmark research for voting equipment used in an election in 2008 or later and/ or... Institute of Standards and Technology (NIST) will be conducting Phase III research on voting equipment...

  7. Experimental and Theoretical Studies on Biologically Active Lanthanide (III) Complexes

    NASA Astrophysics Data System (ADS)

    Kostova, I.; Trendafilova, N.; Georgieva, I.; Rastogi, V. K.; Kiefer, W.

    2008-11-01

    The complexation ability and the binding mode of the ligand coumarin-3-carboxylic acid (HCCA) to La(III), Ce(III), Nd(III), Sm(III), Gd(III) and Dy(III) lanthanide ions (Ln(III)) are elucidated at experimental and theoretical level. The complexes were characterized using elemental analysis, DTA and TGA data as well as 1H NMR and 13C NMR spectra. FTIR and Raman spectroscopic techniques as well as DFT quantum chemical calculations were used for characterization of the binding mode and the structures of lanthanide(III) complexes of HCCA. The metal—ligand binding mode is predicted through molecular modeling and energy estimation of different Ln—CCA structures using B3LYP/6-31G(d) method combined with a large quasi-relativistic effective core potential for lanthanide ion. The energies obtained predict bidentate coordination of CCA- to Ln(III) ions through the carbonylic oxygen and the carboxylic oxygen. Detailed vibrational analysis of HCCA, CCA- and Ln(III) complexes based on both calculated and experimental frequencies confirms the suggested metal—ligand binding mode. The natural bonding analysis predicts strongly ionic character of the Ln(III)-CCA bonding in the- complexes studied. With the relatively resistant tumor cell line K-562 we obtained very interesting in-vitro results which are in accordance with our previously published data concerning the activity of lanthanide(III) complexes with other coumarin derivatives.

  8. 40 CFR Appendix III to Part 261 - [Reserved

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 25 2010-07-01 2010-07-01 false III Appendix III to Part 261 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES (CONTINUED) IDENTIFICATION AND LISTING OF HAZARDOUS WASTE Appendix III to Part 261...

  9. Mechanisms for Fe(III) oxide reduction in sedimentary environments

    USGS Publications Warehouse

    Nevin, Kelly P.; Lovely, Derek R.

    2002-01-01

    Although it was previously considered that Fe(III)-reducing microorganisms must come into direct contact with Fe(III) oxides in order to reduce them, recent studies have suggested that electron-shuttling compounds and/or Fe(III) chelators, either naturally present or produced by the Fe(III)-reducing microorganisms themselves, may alleviate the need for the Fe(III) reducers to establish direct contact with Fe(III) oxides. Studies with Shewanella alga strain BrY and Fe(III) oxides sequestered within microporous beads demonstrated for the first time that this organism releases a compound(s) that permits electron transfer to Fe(III) oxides which the organism cannot directly contact. Furthermore, as much as 450 w M dissolved Fe(III) was detected in cultures of S. alga growing in Fe(III) oxide medium, suggesting that this organism releases compounds that can solublize Fe(III) from Fe(III) oxide. These results contrast with previous studies, which demonstrated that Geobacter metallireducens does not produce electron-shuttles or Fe(III) chelators. Some freshwater aquatic sediments and groundwaters contained compounds, which could act as electron shuttles by accepting electrons from G. metallireducens and then transferring the electrons to Fe(III). However, other samples lacked significant electron-shuttling capacity. Spectroscopic studies indicated that the electron-shuttling capacity of the waters was not only associated with the presence of humic substances, but water extracts of walnut, oak, and maple leaves contained electron-shuttling compounds did not appear to be humic substances. Porewater from a freshwater aquatic sediment and groundwater from a petroleum-contaminated aquifer contained dissolved Fe(III) (4-16 w M), suggesting that soluble Fe(III) may be available as an electron acceptor in some sedimentary environments. These results demonstrate that in order to accurately model the mechanisms for Fe(III) reduction in sedimentary environments it will be necessary

  10. Interactions Between Fe(III)-oxides and Fe(III)-phyllosilicates During Microbial Reduction 2: Natural Subsurface Sediments

    SciTech Connect

    Wu, T.; Griffin, A. M.; Gorski, C. A.; Shelobolina, E. S.; Xu, H.; Kukkadapu, R. K.; Roden, E. E.

    2016-04-19

    Dissimilatory microbial reduction of solid-phase Fe(III)-oxides and Fe(III)-bearing phyllosilicates (Fe(III)-phyllosilicates) is an important process in anoxic soils, sediments, and subsurface materials. Although various studies have documented the relative extent of microbial reduction of single-phase Fe(III)-oxides and Fe(III)-phyllosilicates, detailed information is not available on interaction between these two processes in situations where both phases are available for microbial reduction. The goal of this research was to use the model dissimilatory iron-reducing bacterium (DIRB) Geobacter sulfurreducens to study Fe(III)-oxide vs. Fe(III)-phyllosilicate reduction in a range of subsurface materials and Fe(III)-oxide stripped versions of the materials. Low temperature (12K) Mossbauer spectroscopy was used to infer changes in the relative abundances of Fe(III)-oxide, Fe(III)-phyllosilicate, and phyllosilicate-associated Fe(II) (Fe(II)-phyllosilicate). A Fe partitioning model was employed to analyze the fate of Fe(II) and assess the potential for abiotic Fe(II)-catalyzed reduction of Fe(III)-phyllosilicates. The results showed that in most cases Fe(III)- oxide utilization dominated (70-100 %) bulk Fe(III) reduction activity, and that electron transfer from oxide-derived Fe(II) played only a minor role (ca. 10-20 %) in Fe partitioning. In addition, the extent of Fe(III)-oxide reduction was positively correlated to surface area-normalized cation exchange capacity and the phyllosilicate-Fe(III)/total Fe(III) ratio, which suggests that the phyllosilicates in the natural sediments promoted Fe(III)-oxide reduction by binding of oxide-derived Fe(II), thereby enhancing Fe(III)-oxide reduction by reducing or delaying the inhibitory effect that Fe(II) accumulation on oxide and DIRB cell surfaces has on Fe(III)-oxide reduction. In general our results suggest that although Fe(III)-oxide reduction is likely to dominate bulk Fe(III) reduction in most subsurface sediments, Fe

  11. WAIS-III and WMS-III performance in chronic Lyme disease.

    PubMed

    Keilp, John G; Corbera, Kathy; Slavov, Iordan; Taylor, Michael J; Sackeim, Harold A; Fallon, Brian A

    2006-01-01

    There is controversy regarding the nature and degree of intellectual and memory deficits in chronic Lyme disease. In this study, 81 participants with rigorously diagnosed chronic Lyme disease were administered the newest revisions of the Wechsler Adult Intelligence Scale (WAIS-III) and Wechsler Memory Scale (WMS-III), and compared to 39 nonpatients. On the WAIS-III, Lyme disease participants had poorer Full Scale and Performance IQ's. At the subtest level, differences were restricted to Information and the Processing Speed subtests. On the WMS-III, Lyme disease participants performed more poorly on Auditory Immediate, Immediate, Auditory Delayed, Auditory Recognition Delayed, and General Memory indices. Among WMS-III subtests, however, differences were restricted to Logical Memory (immediate and delayed) and Family Pictures (delayed only), a Visual Memory subtest. Discriminant analyses suggest deficits in chronic Lyme are best characterized as a combination of memory difficulty and diminished processing speed. Deficits were modest, between one-third and two-thirds of a standard deviation, consistent with earlier studies. Depression severity had a weak relationship to processing speed, but little other association to test performance. Deficits in chronic Lyme disease are consistent with a subtle neuropathological process affecting multiple performance tasks, although further work is needed to definitively rule out nonspecific illness effects.

  12. A spectrophotometric study of Nd(III), Sm(III) and Er(III) complexation in sulfate-bearing solutions at elevated temperatures

    NASA Astrophysics Data System (ADS)

    Migdisov, Art. A.; Williams-Jones, A. E.

    2008-11-01

    The speciation of Nd(III), Sm(III), and Er(III) in sulfate-bearing solutions has been determined spectrophotometrically at temperatures from 25 to 250 °C and a pressure of 100 bars. The data obtained earlier on the speciation of Nd in sulfate-bearing solutions ( Migdisov et al., 2006) have been re-evaluated and corrected using a more appropriate activity model and are compared with the corresponding data for Sm(III) and Er(III) and new data for Nd(III). Based on this comparison, the dominant species in the solution are interpreted to be REESO4+ and REE(SO)2-, with the latter complex increasing in importance at higher temperature. Equilibrium constants were calculated for the following reactions:

  13. Solvent extraction behaviour of lanthanum(III), cerium(III), europium(III), thorium(IV) and uranium(VI) with 3-phenyl-4-benzoyl-5-isoxazolone.

    PubMed

    Jyothi, A; Rao, G N

    1990-04-01

    The extraction behaviour of La(III), Ce(III), Eu(III), Th(IV) and U(VI) with 3-phenyl-4- benzoyl-5-isoxazolone (HPBI) in chloroform has been studied. The mechanism of extraction and the species extracted have been identified. Extraction constants for each system have been calculated. The system has been used to separate Th(IV) from U(VI) and from La(III), Ce(III) and Eu(III). A comparison of the extraction constants with those for the 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (HPMBP) and thenoyltrifluoroacetone (HTTA) systems indicates that HPBI extracts these metal species better than HPMBP and HTTA do.

  14. Development and Evaluation of Adeno-HTLV-III Hybrid Virus and Non- Cytopathic HTLV-III Mutant for Vaccine Use

    DTIC Science & Technology

    1988-10-28

    AD_______________ DEVELOPMENT AND EVALUATION OF ADENO- HTLV -III HYBRID VIRUS AND NON- (V) CYTOPATHIC HTLV -III MUTANT FOR VACCINE USE Lf In Annual...Development and Evaluation of Adeno- HTLV -III Hybrid Virus and Non-Cytopathic HTLV -III Mutant for Vaccine Use 12. PERSONAL AUTHOR(S) Lubet, Martha Turner...HIV virus. Assessment of vaccine efficacy against the virus challenge will include T4/T8 ratios, Interleukin-2 production, HTLV -IJT serology and ability

  15. Does As(III) interact with Fe(II), Fe(III) and organic matter through ternary complexes?

    PubMed

    Catrouillet, Charlotte; Davranche, Mélanie; Dia, Aline; Bouhnik-Le Coz, Martine; Demangeat, Edwige; Gruau, Gérard

    2016-05-15

    Up until now, only a small number of studies have been dedicated to the binding processes of As(III) with organic matter (OM) via ionic Fe(III) bridges; none was interested in Fe (II). Complexation isotherms were carried out with As(III), Fe(II) or Fe(III) and Leonardite humic acid (HA). Although PHREEQC/Model VI, implemented with OM thiol groups, reproduced the experimental datasets with Fe(III), the poor fit between the experimental and modeled Fe(II) data suggested another binding mechanism for As(III) to OM. PHREEQC/Model VI was modified to take various possible As(III)-Fe(II)-OM ternary complex conformations into account. The complexation of As(III) as a mononuclear bidentate complex to a bidentate Fe(II)-HA complex was evidenced. However, the model needed to be improved since the distribution of the bidentate sites appeared to be unrealistic with regards to the published XAS data. In the presence of Fe(III), As(III) was bound to thiol groups which are more competitive with regards to the low density of formed Fe(III)-HA complexes. Based on the new data and previously published results, we propose a general scheme describing the various As(III)-Fe-MO complexes that are able to form in Fe and OM-rich waters.

  16. The role of Ce(III) in BZ oscillating reactions

    NASA Astrophysics Data System (ADS)

    Nogueira, Paulo A.; Varela, Hamilton; Faria, Roberto B.

    2012-03-01

    Herein we present results on the oscillatory dynamics in the bromate-oxalic acid-acetone-Ce(III)/Ce(IV) system in batch and also in a CSTR. We show that Ce(III) is the necessary reactant to allow the emergence of oscillations. In batch, oscillations occur with Ce(III) and also with Ce(IV), but no induction period is observed with Ce(III). In a CSTR, no oscillations were found using a freshly prepared Ce(IV), but only when the cerium-containing solution was aged, allowing partial conversion of Ce(IV) to Ce(III) by reaction with acetone.

  17. Removal of arsenic(III) and arsenic(IV) ions from aqueous solutions with lanthanum(III) salt and comparison with aluminum(III), calcium(II), and iron(III) salts

    SciTech Connect

    Tokunaga, S.; Yokoyama, S.; Wasay, S.A.

    1999-05-01

    Interactions of arsenic(III) and arsenic(V) ions with a lanthanum salt were studied with the aim of developing a new precipitation method for removal of arsenic from aqueous solutions. Performance was compared to those of aluminum, polyaluminum chloride (PAC), calcium, and iron(III) salts. Arsenic(III) was removed by iron(III) and lanthanum in a narrow pH range with less than 605 removal. Arsenic(V) was removed more efficiently by aluminum, PAC, iron(III), and lanthanum. Lanthanum was most effective, meeting Japanese effluent and drinking water standards by adding three times as much lanthanum as arsenic(V).

  18. Methods of Prospective Investigation of Pulmonary Embolism Diagnosis III (PIOPED III).

    PubMed

    Stein, Paul D; Gottschalk, Alexander; Sostman, H Dirk; Chenevert, Thomas L; Fowler, Sarah E; Goodman, Lawrence R; Hales, Charles A; Hull, Russell D; Kanal, Emanuel; Leeper, Kenneth V; Nadich, David P; Sak, Daniel J; Tapson, Victor F; Wakefield, Thomas W; Weg, John G; Woodard, Pamela K

    2008-11-01

    In this work, the methods of the Prospective Investigation of Pulmonary Embolism Diagnosis III (PIOPED III) are described in detail. PIOPED III is a multicenter collaborative investigation sponsored by the National Heart, Lung and Blood Institute. The purpose is to determine the accuracy of gadolinium-enhanced magnetic resonance angiography in combination with venous phase magnetic resonance venography for the diagnosis of acute pulmonary embolism (PE). A composite reference standard based on usual diagnostic methods for PE is used. All images will be read by 2 blinded and study-certified central readers. Patients with no PE according to the composite reference test will be randomized to undergo gadolinium-enhanced magnetic resonance angiography in combination with venous phase magnetic resonance venography. This procedure will reduce the proportion of patients with negative tests at no loss in evaluation of sensitivity and specificity.

  19. Methods of Prospective Investigation of Pulmonary Embolism Diagnosis III (PIOPED III)

    PubMed Central

    Stein, Paul D.; Gottschalk, Alexander; Sostman, H. Dirk; Chenevert, Thomas L.; Fowler, Sarah E.; Goodman, Lawrence R.; Hales, Charles A.; Hull, Russell D.; Kanal, Emanuel; Leeper, Kenneth V.; Nadich, David P.; Sak, Daniel J; Tapson, Victor F.; Wakefield, Thomas W.; Weg, John G.; Woodard, Pamela K.

    2008-01-01

    The methods of the Prospective Investigation of Pulmonary Embolism Diagnosis III (PIOPED III) are described in detail. PIOPED III is a multicenter collaborative investigation sponsored by the National Heart, Lung and Blood Institute. The purpose is to determine the accuracy of gadolinium-enhanced magnetic resonance angiography (Gd-MRA) in combination with venous phase magnetic resonance venography (Gd-MRV) for the diagnosis for acute pulmonary embolism (PE). A composite reference standard based on usual diagnostic methods for pulmonary embolism is used. All images will be read by two blinded and study-certified central readers. Patients with no PE according to the composite reference test will be randomized to undergo Gd-MRA/MRV. This will reduce the proportion of patients with negative tests at no loss in evaluation of sensitivity and specificity. PMID:19331840

  20. Decorating the lanthanide terminus of self-assembled heterodinuclear lanthanum(III)/gallium(III) helicates.

    PubMed

    Albrecht, Markus; Latorre, Irene; Mehmeti, Gent; Hengst, Konstantin; Oppel, Iris M

    2011-12-07

    Arylacylhydrazones of 2,3-dihydroxybenzaldehyde are appropriate ligands for the preparation of heterodinuclear triple-stranded helicates involving high coordinated lanthanide(III) ions. In the present study, three different kinds of substituents are introduced at the ligands in order to modify the organic periphery of the coordination compounds: (1) alkoxy groups are attached to the terminal phenyl groups, (2) NH protons of the hydrazones are substituted by phenyl moieties and (3) amino acid bearing units are attached to the terminus of the ligand. The new ligands nicely form the desired triple-stranded gallium(III)-lanthanum(III) complexes [(5a-c,7,12,15)(3)GaLa] of which the highly phenylated derivative was crystallized and studied by X-ray diffraction.

  1. A binuclear Fe(III)Dy(III) single molecule magnet. Quantum effects and models.

    PubMed

    Ferbinteanu, Marilena; Kajiwara, Takashi; Choi, Kwang-Yong; Nojiri, Hiroyuki; Nakamoto, Akio; Kojima, Norimichi; Cimpoesu, Fanica; Fujimura, Yuichi; Takaishi, Shinya; Yamashita, Masahiro

    2006-07-19

    The binuclear [FeIII(bpca)(mu-bpca)Dy(NO3)4], having Single Molecule Magnet (SMM) properties, belonging to a series of isostructural FeIIILnIII complexes (Ln = Eu, Gd, Tb, Dy, Ho) and closely related FeIILnIII chain structures, was characterized in concise experimental and theoretical respects. The low temperature magnetization data showed hysteresis and tunneling. The anomalous temperature dependence of Mössbauer spectra is related to the onset of magnetic order, consistent with the magnetization relaxation time scale resulting from AC susceptibility measurements. The advanced ab initio calculations (CASSCF and spin-orbit) revealed the interplay of ligand field, spin-orbit, and exchange effects and probed the effective Ising nature of the lowest states, involved in the SMM and tunneling effects.

  2. Solubility of Fe(III) in seawater

    NASA Astrophysics Data System (ADS)

    Millero, Frank J.

    1998-01-01

    Recently Kuma et al. [K. Kuma, J. Nishioka, K. Matsunaga, Controls on iron (III) hydroxide solubility in seawater: The influence of pH and natural organic chelators, Limnol. Oceanogr. 41 (1996) 396-407] made some careful measurements of the solubility of Fe(III) in UV and non-UV irradiated seawater as a function of pH (5-8). They showed that organic compounds can increase the solubility (32-65%) at pH=8.1, apparently due to the formation of Fe(III) organic complexes. In this paper I have examined how these results can be quantified using a speciation model for Fe(III). The results indicate that the effect of pH (2-9) on coastal and open ocean waters by Kuma et al. and the earlier filtration measurement of Byrne and Kester [R.H. Byrne, D.R. Kester, Solubility of hydrous ferric oxide and iron speciation in sea water, Mar. Chem. 4 (1976) 255-274] can be adequately represented by considering the formation of FeOH 2+ and Fe(OH) 2+ using the hydrolysis constants ( K ∗1=10 -2.62, K ∗2=10 -6.0) determined by Millero et al. [F.J. Millero, W. Yao, J. Aicher, The speciation of Fe(II) and Fe(III) in natural waters, Mar. Chem. 50 (1995) 21-39]. The solubility measurements [Kuma et al., 1996] on unaltered coastal and open ocean waters appear to require the consideration of the formation of Fe(OH) 30 ( K ∗3=10 -13.3-10 -14.3). A more careful look at these measurements indicates that the curvature between pH 7 and 8 can be attributed to the formation of complexes of Fe 3+ with organic ligands (FeL). Model speciation calculations (pH 6-8) yield total ligand concentrations of [L] T=1.2 nM and 0.17 nM for unaltered coastal and open ocean waters, respectively, assuming K' FeL=10 21. These estimates are in good agreement with the values found for ocean waters by voltammetric methods. The model calculations for the solubility of Fe(III) (0.2 nM at pH=8.1 and 0.6 nM at pH=7.65) are in good agreement with measured open ocean surface (0.2 nM) and deep waters (0.6 nM) determined by

  3. Approaching actinide(+III) hydration from first principles.

    PubMed

    Wiebke, J; Moritz, A; Cao, X; Dolg, M

    2007-01-28

    A systematic computational approach to An(III) hydration on a density-functional level of theory, using quasi-relativistic 5f-in-core pseudopotentials and valence-only basis sets for the An(III) subsystems, is presented. Molecular structures, binding energies, hydration energies, and Gibbs free energies of hydration have been calculated for [An(III)(OH(2))(h)](3+) (h = 7, 8, 9) and [An(III)(OH(2))(h-1) * OH(2)](3+) (h = 8, 9), using large (7s6p5d2f1g)/[6s5p4d2f1g] An(III) and cc-pVQZ O and H basis sets within the COSMO implicit solvation model. An(III) preferred primary hydration numbers are found to be 8 for all An(III) at the gradient-corrected density-functional level of theory. Second-order Møller-Plesset perturbation theory predicts preferred primary hydration numbers of 9 and 8 for Ac(III)-Md(III) and No(III)-Lr(III), respectively.

  4. Central and peripheral cardiovascular effects of angiotensin III in trout.

    PubMed

    Mimassi, N; Lancien, F; Le Mével, J C

    2009-04-01

    The present study was undertaken to determine the central and peripheral actions of trout angiotensin III (ANG III) on heart rate (HR) and mean dorsal aortic blood pressure (P(DA)) in the unanaesthetized rainbow trout. Intracerebroventricular injection of ANG III (5-100 pmol) produced a significant and dose-dependent increase in HR without significant change in P(DA). In contrast, when injected peripherally ANG III (5-50 pmol) evoked a significant and dose-dependent increase in P(DA). The hypertensive responses were accompanied by a bradycardia that reached significance only for the highest dose of ANG III tested. In conclusion, our results have shown that ANG III has potent and contrasting cardiovascular actions depending on whether its site of action is the brain or the peripheral circulation. Endogenous ANG III may have important physiological functions in teleost fishes.

  5. Ribonuclease revisited: structural insights into ribonuclease III family enzymes.

    PubMed

    MacRae, Ian J; Doudna, Jennifer A

    2007-02-01

    Ribonuclease III (RNase III) enzymes occur ubiquitously in biology and are responsible for processing RNA precursors into functional RNAs that participate in protein synthesis, RNA interference and a range of other cellular activities. Members of the RNase III enzyme family, including Escherichia coli RNase III, Rnt1, Dicer and Drosha, share the ability to recognize and cleave double-stranded RNA (dsRNA), typically at specific positions or sequences. Recent biochemical and structural data have shed new light on how RNase III enzymes catalyze dsRNA hydrolysis and how substrate specificity is achieved. A major theme emerging from these studies is that accessory domains present in different RNase III enzymes are the key determinants of substrate selectivity, which in turn dictates the specialized biological function of each type of RNase III protein.

  6. Semiconductors A(III)B(VI): Translation

    NASA Astrophysics Data System (ADS)

    Akhundov, G. A.; Abdullaev, G. B.; Guseynov, G. D.; Mekhtiyev, R. F.; Aliyeva, M. Kh.

    1993-11-01

    Semiconductors A(III) B(VI) crystallize in laminated or chain structures and contain nine valence electrons in each molecule. Connection in the layers and the chains is predominantly covalent, and Van der Waal between the layers and the chains. Calculated data of the energy spectrum of these compounds are absent, and the available experimental studies are insufficient for understanding of the zone structures. We have obtained and studied single crystals of GaS, GaSe, GaTe, InSe, and TiSe.

  7. Intercalation of Europium (III) species into bentonite

    SciTech Connect

    Sanchez, A.; Echeverria, Y.; Torres, C.M. Sotomayor; Gonzalez, G.; Benavente, E. . E-mail: ebenaven@uchile.cl

    2006-06-15

    It is shown that the intercalation of [Europium(bipyridine){sub 2}]{sup 3+} into bentonite results in a new nanocomposite which preserves the emission properties of Europium (III). The exchange of sodium by europium in bentonite is correlated with the cation exchange capacity and molecular size. The intercalated complex exhibits luminescence where both the 2,2-bipyridine 'antenna' effect and the intensity maxima are comparable to the free complex suggesting that clay intercalated with rare earths may results in novel optical materials.

  8. Have We Finally Found Pop III Stars?

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2015-08-01

    Elusive Population: Population III stars — the theoretical generation of extremely metal-poor stars that should have been formed in the early universe before metals existed — have been conspicuously absent in observations. But a team led by David Sobral (Institute of Astrophysics and Space Sciences, University of Lisbon, and Leiden Observatory) may have changed this paradigm with their recent detection of an extremely bright galaxy in the early universe. The team's broad survey of distant galaxies using ESO's Very Large Telescope provides a glimpse of the universe as it was only 800 million years after the Big Bang. The survey uncovered several unusually bright galaxies — including the brightest galaxy ever seen at this distance, an important discovery by itself. But further scrutiny of this galaxy, named CR7, produced an even more exciting find: a bright pocket of the galaxy contained no sign of any metals. Follow-up with other telescopes confirmed this initial detection. Formation Waves: Sobral and his team postulate that we are observing this galaxy at just the right time to have caught a cluster of Population III stars — the bright, metal-free region of the galaxy — at the end of a wave of early star formation. The observations of CR7 also suggest the presence of regular stars in clumps around the metal-free pocket. These older, surrounding clusters may have formed stars first, helping to ionize a local bubble in the galaxy and allowing us to now observe the light from CR7. It was previously thought that Population III stars might only be found in small, dim galaxies, making them impossible for us to detect. But CR7 provides an interesting alternative: this galaxy is bright, and the candidate Population III stars are surrounded by clusters of normal stars. This suggests that these first-generation stars might in fact be easier to detect than was originally thought. Additional follow-up observations with other telescopes will help to confirm the

  9. Space Processing Applications Rocket project SPAR III

    NASA Technical Reports Server (NTRS)

    Reeves, F.

    1978-01-01

    This document presented the engineering report and science payload III test report and summarized the experiment objectives, design/operational concepts, and final results of each of five scientific experiments conducted during the third Space Processing Applications Rocket (SPAR) flight flown by NASA in December 1976. The five individual SPAR experiments, covering a wide and varied range of scientific materials processing objectives, were entitled: Liquid Mixing, Interaction of Bubbles with Solidification Interfaces, Epitaxial Growth of Single Crystal Film, Containerless Processing of Beryllium, and Contact and Coalescence of Viscous Bodies.

  10. III Astronomy School: the world of stars

    NASA Astrophysics Data System (ADS)

    Valdivielso, L.

    2015-05-01

    The Astronomy School is an activity organized by the Centro de Estudios de Física del Cosmos de Aragón. It is celebrated every year at the end of the summer or the beginning of autumn with the purpose of bringing Astronomy and Astrophysics to the population from an educational and a training point of view. Its III Edition, held in October 2013, has been financed by the Spanish Astronomical Society and was focused on stellar physics. This contribution describes the School and the results.

  11. The Trident III radio position finding system

    NASA Astrophysics Data System (ADS)

    Gaudin, J.-C.; Chantome, M.

    1980-07-01

    The Trident III radio position finding system is based on the precise and simultaneous measurement of the distances between an interrogator and two, three or four responding markers at perfectly determined geodesic points. Attention is given to the pulse duration (0.35 to 0.5 microsec) and emission and reception frequencies of the marker and interrogator, as well as to the structure of the data and information. It is noted that when associated with a programmable calculator, the system is capable of use as a guiding system.

  12. Treatment of Class III with Facemask Therapy

    PubMed Central

    Pattanaik, Snigdha; Mishra, Sumita

    2016-01-01

    Class III malocclusion is one of the most difficult problems to treat in the mixed dentition. It has a multifactorial etiology involving both genetic and environmental causes. The dental and skeletal effects of maxillary protraction with a facemask are well documented in several studies. Although treatment in the late mixed or early permanent dentition can be successful, results are generally better in the deciduous or early mixed dentition. The following case shows early treatment of a young patient with severe sagittal and transverse discrepancy of the maxilla and mandible, using a facemask. PMID:26925273

  13. Oxidative UO2 dissolution induced by soluble Mn(III).

    PubMed

    Wang, Zimeng; Xiong, Wei; Tebo, Bradley M; Giammar, Daniel E

    2014-01-01

    The stability of UO2 is critical to the success of reductive bioremediation of uranium. When reducing conditions are no longer maintained, Mn redox cycling may catalytically mediate the oxidation of UO2 and remobilization of uranium. Ligand-stabilized soluble Mn(III) was recently recognized as an important redox-active intermediate in Mn biogeochemical cycling. This study evaluated the kinetics of oxidative UO2 dissolution by soluble Mn(III) stabilized by pyrophosphate (PP) and desferrioxamine B (DFOB). The Mn(III)-PP complex was a potent oxidant that induced rapid UO2 dissolution at a rate higher than that by a comparable concentration of dissolved O2. However, the Mn(III)-DFOB complex was not able to induce oxidative dissolution of UO2. The ability of Mn(III) complexes to oxidize UO2 was probably determined by whether the coordination of Mn(III) with ligands allowed the attachment of the complexes to the UO2 surface to facilitate electron transfer. Systematic investigation into the kinetics of UO2 oxidative dissolution by the Mn(III)-PP complex suggested that Mn(III) could directly oxidize UO2 without involving particulate Mn species (e.g., MnO2). The expected 2:1 reaction stoichiometry between Mn(III) and UO2 was observed. The reactivity of soluble Mn(III) in oxidizing UO2 was higher at lower ratios of pyrophosphate to Mn(III) and lower pH, which is probably related to differences in the ligand-to-metal ratio and/or protonation states of the Mn(III)-pyrophosphate complexes. Disproportionation of Mn(III)-PP occurred at pH 9.0, and the oxidation of UO2 was then driven by both MnO2 and soluble Mn(III). Kinetic models were derived that provided excellent fits of the experimental results.

  14. Luminescence spectroscopy of europium(III) and terbium(III) penta-, octa- and nonanuclear clusters with beta-diketonate ligands.

    PubMed

    Petit, Sarah; Baril-Robert, François; Pilet, Guillaume; Reber, Christian; Luneau, Dominique

    2009-09-14

    A series of Eu(III) and Tb(III) clusters as well as their Y(III) analogues with increasing nuclearities of 5, 8 and 9 have been synthesised using beta-diketonate ligands with decreasing steric hindrance. Their molecular structures have been established from X-ray diffraction on single crystals for most clusters and studied by luminescence and Raman spectroscopy. The Raman spectra have distinctive patterns for each nuclearity in accordance with their crystal structure. The luminescence spectra of the Eu(III) and Tb(III) clusters also show distinctive features.

  15. Performance characteristics of postacute traumatic brain injury patients on the WAIS-III and WMS-III.

    PubMed

    Axelrod, B N; Fichtenberg, N L; Liethen, P C; Czarnota, M A; Stucky, K

    2001-12-01

    Publication of the third editions of the Wechsler intelligence and memory batteries in 1997 created a need for research identifying Wechsler Adult Intelligence Scale-Third Edition/Wechsler Memory Scale-Third Edition (WAIS-III/WMS-III) profile patterns associated with neuropathology. The WAIS-III/WMS-III Technical Manual offers data on various diagnostic groups, including traumatic brain injury (TBI). Hawkins (1998) employed Technical Manual data to propose certain diagnostic guidelines. In order to validate the conclusions put forth by Hawkins as they apply to brain injury, we examined WAIS-III and WMS-III profiles in an independent sample of 46 TBI cases. As expected, the WAIS-III Processing Speed Index (PSI) was more sensitive to brain injury than other WAIS-III composites; and specific WAIS-III scores were stronger than certain WMS-III scores. On the other hand, the predicted relationship for WMS-III auditory and visual indexes was not found. The lack of specificity for TBI of the proposed index comparisons confirms the need to validate such hypotheses in independent samples.

  16. White Light Emissive Dy(III) Single-Molecule Magnets Sensitized by Diamagnetic [Co(III) (CN)6 ](3-) Linkers.

    PubMed

    Chorazy, Szymon; Rams, Michał; Nakabayashi, Koji; Sieklucka, Barbara; Ohkoshi, Shin-Ichi

    2016-05-23

    The self-assembly of Dy(III) -3-hydroxypyridine (3-OHpy) complexes with hexacyanidocobaltate(III) anions in water produces cyanido-bridged {[Dy(III) (3-OHpy)2 (H2 O)4 ] [Co(III) (CN)6 ]}⋅H2 O (1) chains. They reveal a single-molecule magnet (SMM) behavior with a large zero direct current (dc) field energy barrier, ΔE=266(12) cm(-1) (≈385 K), originating from the single-ion property of eight-coordinated Dy(III) of an elongated dodecahedral geometry, which are embedded with diamagnetic [Co(III) (CN)6 ](3-) ions into zig-zag coordination chains. The SMM character is enhanced by the external dc magnetic field, which results in the ΔE of 320(23) cm(-1) (≈460 K) at Hdc =1 kOe, and the opening of a butterfly hysteresis loop below 6 K. Complex 1 exhibits white Dy(III) -based emission realized by energy transfer from Co(III) and 3-OHpy to Dy(III) . Low temperature emission spectra were correlated with SMM property giving the estimation of the zero field ΔE. 1 is a unique example of bifunctional magneto-luminescent material combining white emission and slow magnetic relaxation with a large energy barrier, both controlled by rich structural and electronic interplay between Dy(III) , 3-OHpy, and [Co(III) (CN)6 ](3-) .

  17. ARIES-III divertor engineering design

    SciTech Connect

    Wong, C.P.C.; Schultz, K.R.; Cheng, E.T.; Grotz, S.; Hasan, M.A.; Najmabadi, F.; Sharafat, S.; Brooks, J.N.; Ehst, D.A.; Sze, D.K.; Herring, J.S.; Valenti, M.; Steiner, D.

    1992-01-01

    This paper reports the engineering design of the ARIES-III double- null divertor. The divertor coolant tubes are made from W-3Re alloy and cooled by subcooled flow boiling of organic coolant. A coating of 4 mm thick tungsten is plasma sprayed onto the divertor surface. This W layer can withstand the thermal deposition of a few disruptions. At a maximum surface heat flux of 5.4 MW/m{sup 2}, a conventional divertor design can be used. The divertor surface is contoured to have a constant heat flux of 5.4 MW/m{sup 2}. The net erosion of the W-surface was found to be negligible at about 0.1 mm/year. After 3 years of operation, the W-3Re alloy ARIES-III divertor can be disposed of as Class A waste. In order to control the prompt dose release at site boundary to less than 200 Rem, isotopic tailoring of the W-alloy will be needed.

  18. Lanthanum(III) and praseodymium(III) complexes with isatin thiosemicarbazones.

    PubMed

    Rai, Anita; Sengupta, Soumitra K; Pandey, Om P

    2005-09-01

    Ten new lanthanum(III) and praseodymium(III) complexes of the general formula Na[La(L)2H2O] (Ln=La(III) or Pr(III); LH2=thiosemicarbazones) derived from the condensation of isatin with 4-phenyl thiosemicarbazide, 4-(4-chlorophenyl) thiosemicarbazide, 4-(2-nitrophenyl) thiosemicarbazide, 4-(2-bromophenyl) thiosemicarbazide and 4-(2-methylphenyl) thiosemicarbazide, have been synthesized in methanol in presence of sodium hydroxide. The XRD spectra of the complexes were monitored to verify complex formation. The complexes have also been characterized by elemental analysis, molar conductance, electronic absorption and fluorescence, infrared, far infrared, 1H and 13C NMR spectral studies. Thermal studies of these complexes have been carried out in the temperature range 25-800 degrees C using TG, DTG and DTA techniques. All these complexes decompose gradually with the formation of Ln2O3 as the end product. The Judd-ofelt intensity parameter, oscillator strength, transition probability, stimulated emission cross section for different transitions of Pr3+ for 4-phenyl thiosemicarbazones have been calculated.

  19. Sloan Digital Sky Survey III (SDSS-III), Data Release 8

    DOE Data Explorer

    Building on the legacy of the Sloan Digital Sky Survey (SDSS) and SDSS-II, the SDSS-III Collaboration is working to map the Milky Way, search for extrasolar planets, and solve the mystery of dark energy. SDSS-III's first release, Data Release 8 (DR8), became available in the first half of 2012. DR8 contains all the images ever taken by the SDSS telescope. Together, these images make up the largest color image of the sky ever made. A version of the DR8 image is shown to the right. DR8 also includes measurements for nearly 500 million stars, galaxies, and quasars, and spectra for nearly two million. All of DR8's images, spectra, and measurements are available to anyone online. You can browse through sky images, look up data for individual objects, or search for objects anywhere using any criteria. SDSS-III will collect data from 2008 to 2014, using the 2.5-meter telescope at Apache Point Observatory. SDSS-III consists of four surveys, each focused on a different scientific theme. These four surveys are: 1) Baryon Oscillation Spectroscopic Survey (BOSS); 2) SEGUE-2 (Sloan Extension for Galactic Understanding and Exploration); 3) The APO Galactic Evolution Experiment (APOGEE); and 4) The Multi-object APO Radial Velocity Exoplanet Large-area Survey (MARVELS). [Copied with edits from http://www.sdss3.org/index.php

  20. Stratospheric Aerosol and Gas Experiment III on the International Space Station (SAGE III/ISS)

    NASA Technical Reports Server (NTRS)

    Gasbarre, Joseph; Walker, Richard; Cisewski, Michael; Zawodny, Joseph; Cheek, Dianne; Thornton, Brooke

    2015-01-01

    The Stratospheric Aerosol and Gas Experiment III on the International Space Station (SAGE III/ISS) mission will extend the SAGE data record from the ideal vantage point of the International Space Station (ISS). The ISS orbital inclination is ideal for SAGE measurements providing coverage between 70 deg north and 70 deg south latitude. The SAGE data record includes an extensively validated data set including aerosol optical depth data dating to the Stratospheric Aerosol Measurement (SAM) experiments in 1975 and 1978 and stratospheric ozone profile data dating to the Stratospheric Aerosol and Gas Experiment (SAGE) in 1979. These and subsequent data records, notably from the SAGE II experiment launched on the Earth Radiation Budget Satellite in 1984 and the SAGE III experiment launched on the Russian Meteor-3M satellite in 2001, have supported a robust, long-term assessment of key atmospheric constituents. These scientific measurements provide the basis for the analysis of five of the nine critical constituents (aerosols, ozone (O3), nitrogen dioxide (NO2), water vapor (H2O), and air density using O2) identified in the U.S. National Plan for Stratospheric Monitoring. SAGE III on ISS was originally scheduled to fly on the ISS in the same timeframe as the Meteor-3M mission, but was postponed due to delays in ISS construction. The project was re-established in 2009.

  1. Synthesis of Imine-Naphthol Tripodal Ligand and Study of Its Coordination Behaviour towards Fe(III), Al(III), and Cr(III) Metal Ions

    PubMed Central

    Kaur, Kirandeep

    2014-01-01

    A hexadentate Schiff base tripodal ligand is synthesized by the condensation of tris (2-aminoethyl) amine with 2-hydroxy-1-naphthaldehyde and characterized by various spectroscopic techniques like UV-VIS, IR, NMR, MASS, and elemental analysis. The solution studies by potentiometric and spectrophotometric methods are done at 25 ± 1°C, µ = 0.1 M KCl, to calculate the protonation constants of the ligand and formation constants of metal complexes formed by the ligand with Fe(III), Al(III), and Cr(III) metal ions. The affinity of the ligand towards Fe(III) is compared with deferiprone (a drug applied for iron intoxication) and transferrin (the main Fe(III) binding protein in plasma). Structural analysis of the ligand and the metal complexes was done using semiempirical PM6 method. Electronic and IR spectra are calculated by semiempirical methods and compared with experimental one. PMID:25294978

  2. Variation in plasmonic (electronic) spectral parameters of Pr (III) and Nd (III) with varied concentration of moderators

    SciTech Connect

    Mishra, Shubha; Limaye, S. N.

    2015-07-31

    It is said that the -4f shells behave as core and are least perturbed by changes around metal ion surrounding. However, there are evidences that-4f shells partially involved in direct moderator interaction. A systematic investigation on the plasmonic (electronic) spectral studies of some Rare Earths[RE(III).Mod] where, RE(III) = Pr(III),Nd(III) and Mod(moderator) = Y(III),La(III),Gd(III) and Lu(III), increased moderator concentration from 0.01 mol dm{sup −3} to 0.025 mol dm{sup −3} keeping the metal ion concentration at 0.01mol dm{sup −3} have been carried out. Variations in oscillator strengths (f), Judd-Ofelt parameters (T{sub λ}),inter-electronic repulsion Racah parameters (δE{sup k}),nephelauxetic ratio (β), radiative parameters (S{sub ED},A{sub T},β{sub R},T{sub R}). The values of oscillator strengths and Judd-Ofelt parameters have been discussed in the light of coordination number of RE(III) metal ions, denticity and basicity of the moderators. The [RE(III).Mod] bonding pattern has been studies in the light of the change in Racah parameters and nephelauxetic ratio.

  3. Expression of anti-neuroexcitation peptide III of scorpion Buthus martensii Karsch BmK ANEP III in plants.

    PubMed

    Song, Y B; Huang, T T; Lai, L L; Zhou, J; Yang, W Y; Zhang, J H

    2011-01-01

    Anti-neuroexcitation peptide III of Buthus martensii Karsch (BmK ANEP III) has better anti-epileptic and anticonvulsive effects in the test animal models. The present study is aimed at developing transgenic tomato and tobacco lines overproducing the ANEP III protein. Using the molecular cloning technique, the plant expression vector pBI-ANEP III was constructed successfully. The ANEP III expression cassette included a double CaMV 35S promoter with omega enhancers, the ANEP III gene with the Kozak sequence, the ER retention signal and the NOS terminator. Recombinant plasmids were transferred into Agrobacterium tumefaciens EHA105 by freeze-thaw transformation methods. By the Agrobacterium-mediated leaf disc transformation method, tobacco (Nicotiana tabacum) and tomato (Lycopersicum esculentum) lines were transformed. Transformants were screened and confirmed by PCR, RT-PCR and western blotting analysis. It was demonstrated that the ANEP III gene was successfully expressed in the genomic DNA of transgenic plants. The ANEP III protein was detected by immunofluorescence analysis, and the results confirmed the high amount of ANEP III protein, being 0.81 and 1.08% of total soluble proteins in transgenic tobacco and tomato. The study of plants with high expression levels of ANEP III has an important theoretical and practical significance and provides valuable information for establishing a new, economical and effective system for industrial protein production.

  4. Uranium (III) precipitation in molten chloride by wet argon sparging

    NASA Astrophysics Data System (ADS)

    Vigier, Jean-François; Laplace, Annabelle; Renard, Catherine; Miguirditchian, Manuel; Abraham, Francis

    2016-06-01

    In the context of pyrochemical processes for nuclear fuel treatment, the precipitation of uranium (III) in molten salt LiCl-CaCl2 (30-70 mol%) at 705 °C is studied. First, this molten chloride is characterized with the determination of the water dissociation constant. With a value of 10-4.0, the salt has oxoacid properties. Then, the uranium (III) precipitation using wet argon sparging is studied. The salt is prepared using UCl3 precursor. At the end of the precipitation, the salt is totally free of solubilized uranium. The main part is converted into UO2 powder but some uranium is lost during the process due to the volatility of uranium chloride. The main impurity of the resulting powder is calcium. The consequences of oxidative and reductive conditions on precipitation are studied. Finally, coprecipitation of uranium (III) and neodymium (III) is studied, showing a higher sensitivity of uranium (III) than neodymium (III) to precipitation.

  5. Detecting population III galaxies with HST and JWST

    NASA Astrophysics Data System (ADS)

    Zackrisson, E.

    2012-09-01

    A small fraction of the atomic-cooling halos assembling at z < 15 may form out of minihalos that never experienced any prior star formation, and could in principle host small galaxies of chemically unenriched stars. Since the prospects of detecting isolated population III stars appear bleak even with the upcoming James Webb Space Telescope (JWST), these population III galaxies may offer one of the best probes of population III stars in the foreseeable future. By projecting the results from population III galaxy simulations through cluster magnification maps, we predict the fluxes and surface number densities of pop III galaxy galaxies as a function of their typical star formation efficiency. We argue that a small number of lensed population III galaxies in principle could turn up at z ~ 7-10 in the ongoing Hubble Space Telecope survey CLASH, which covers a total of 25 low-redshift galaxy clusters.

  6. AUTOCLASS III - AUTOMATIC CLASS DISCOVERY FROM DATA

    NASA Technical Reports Server (NTRS)

    Cheeseman, P. C.

    1994-01-01

    The program AUTOCLASS III, Automatic Class Discovery from Data, uses Bayesian probability theory to provide a simple and extensible approach to problems such as classification and general mixture separation. Its theoretical basis is free from ad hoc quantities, and in particular free of any measures which alter the data to suit the needs of the program. As a result, the elementary classification model used lends itself easily to extensions. The standard approach to classification in much of artificial intelligence and statistical pattern recognition research involves partitioning of the data into separate subsets, known as classes. AUTOCLASS III uses the Bayesian approach in which classes are described by probability distributions over the attributes of the objects, specified by a model function and its parameters. The calculation of the probability of each object's membership in each class provides a more intuitive classification than absolute partitioning techniques. AUTOCLASS III is applicable to most data sets consisting of independent instances, each described by a fixed length vector of attribute values. An attribute value may be a number, one of a set of attribute specific symbols, or omitted. The user specifies a class probability distribution function by associating attribute sets with supplied likelihood function terms. AUTOCLASS then searches in the space of class numbers and parameters for the maximally probable combination. It returns the set of class probability function parameters, and the class membership probabilities for each data instance. AUTOCLASS III is written in Common Lisp, and is designed to be platform independent. This program has been successfully run on Symbolics and Explorer Lisp machines. It has been successfully used with the following implementations of Common LISP on the Sun: Franz Allegro CL, Lucid Common Lisp, and Austin Kyoto Common Lisp and similar UNIX platforms; under the Lucid Common Lisp implementations on VAX/VMS v5

  7. The type III effectors of Xanthomonas.

    PubMed

    White, Frank F; Potnis, Neha; Jones, Jeffrey B; Koebnik, Ralf

    2009-11-01

    A review of type III effectors (T3 effectors) from strains of Xanthomonas reveals a growing list of candidate and known effectors based on functional assays and sequence and structural similarity searches of genomic data. We propose that the effectors and suspected effectors should be distributed into 39 so-called Xop groups reflecting sequence similarity. Some groups have structural motifs for putative enzymatic functions, and recent studies have provided considerable insight into the interaction with host factors in their function as mediators of virulence and elicitors of resistance for a few specific T3 effectors. Many groups are related to T3 effectors of plant and animal pathogenic bacteria, and several groups appear to have been exploited primarily by Xanthomonas species based on available data. At the same time, a relatively large number of candidate effectors remain to be examined in more detail with regard to their function within host cells.

  8. Disconnecting XRCC1 and DNA ligase III.

    PubMed

    Katyal, Sachin; McKinnon, Peter J

    2011-07-15

    DNA strand break repair is essential for the prevention of multiple human diseases, particularly those which feature neuropathology. To further understand the pathogenesis of these syndromes, we recently developed animal models in which the DNA single-strand break repair (SSBR) components, XRCC1 and DNA Ligase III (LIG3), were inactivated in the developing nervous system. Although biochemical evidence suggests that inactivation of XRCC1 and LIG3 should share common biological defects, we found profound phenotypic differences between these two models, implying distinct biological roles for XRCC1 and LIG3 during DNA repair. Rather than a key role in nuclear DNA repair, we found LIG3 function was central to mitochondrial DNA maintenance. Instead, our data indicate that DNA Ligase 1 is the main DNA ligase for XRCC1-mediated DNA repair. These studies refine our understanding of DNA SSBR and the etiology of neurological disease.

  9. Advanced Emissions Control Development Program: Phase III

    SciTech Connect

    G.T. Amrhein; R.T. Bailey; W. Downs; M.J. Holmes; G.A. Kudlac; D.A. Madden

    1999-07-01

    The primary objective of the Advanced Emissions Control Development Program (AECDP) is to develop practical, cost-effective strategies for reducing the emissions of air toxics from coal-fired boilers. The project goal is to effectively control air toxic emissions through the use of conventional flue gas clean-up equipment such as electrostatic precipitators (ESPs), fabric filters (baghouses - BH), and wet flue gas desulfurization systems (WFGD). Development work concentrated on the capture of trace metals, fine particulate, hydrogen chloride and hydrogen fluoride, with an emphasis on the control of mercury. The AECDP project is jointly funded by the US Department of Energy's Federal Energy Technology Center (DOE), the Ohio Coal Development Office within the Ohio Department of Development (OCDO), and Babcock and Wilcox, a McDermott company (B and W). This report discusses results of all three phases of the AECDP project with an emphasis on Phase III activities. Following the construction and evaluation of a representative air toxics test facility in Phase I, Phase II focused on characterization of the emissions of mercury and other air toxics and the control of these emissions for typical operating conditions of conventional flue gas clean-up equipment. Some general comments that can be made about the control of air toxics while burning a high-sulfur bituminous coal are as follows: (1) particulate control devices such as ESP's and baghouses do a good job of removing non-volatile trace metals, (2) particulate control devices (ESPs and baghouses) effectively remove the particulate-phase mercury, but the particulate-phase mercury was only a small fraction of the total for the coals tested, (3) wet scrubbing can effectively remove hydrogen chloride and hydrogen fluoride, and (4) wet scrubbers show good potential for the removal of mercury when operated under certain conditions, however, for certain applications, system enhancements can be required to achieve high

  10. The NATO III 5 MHz Distribution System

    NASA Technical Reports Server (NTRS)

    Vulcan, A.; Bloch, M.

    1981-01-01

    A high performance 5 MHz distribution system is described which has extremely low phase noise and jitter characteristics and provides multiple buffered outputs. The system is completely redundant with automatic switchover and is self-testing. Since the 5 MHz reference signals distributed by the NATO III distribution system are used for up-conversion and multiplicative functions, a high degree of phase stability and isolation between outputs is necessary. Unique circuit design and packaging concepts insure that the isolation between outputs is sufficient to quarantee a phase perturbation of less than 0.0016 deg when other outputs are open circuited, short circuited or terminated in 50 ohms. Circuit design techniques include high isolation cascode amplifiers. Negative feedback stabilizes system gain and minimizes circuit phase noise contributions. Balanced lines, in lieu of single ended coaxial transmission media, minimize pickup.

  11. Titan III - Commercial access to space

    NASA Astrophysics Data System (ADS)

    Gizinski, Stephen J., III; Herrington, Douglas B.

    1988-06-01

    The commercial Titan III launch vehicle is discussed, reviewing the history of the Titan program, the technical aspects of the launcher, and the market outlook. The solid rocket motors of the boost vehicle, core, attitude control system, and payload carrier are described. The vehicle can carry one or two payloads taking up a space of up to 3.65 m in diameter and 10.7 m in length. The avionics, communications, and electrical power systems of the vehicle are examined and the range of perigree stages with which the vehicle is compatible is given. An overview of the mission and the launch facilities is presented and future markets for commercial satellites are considered.

  12. Structural characterization of dimeric murine aminoacylase III.

    PubMed

    Ryazantsev, Sergey; Abuladze, Natalia; Newman, Debra; Bondar, Galyna; Kurtz, Ira; Pushkin, Alexander

    2007-05-01

    Aminoacylase III (AAIII) plays an important role in deacetylation of acetylated amino acids and N-acetylated S-cysteine conjugates of halogenated alkenes and alkanes. AAIII, recently cloned from mouse kidney and partially characterized, is a mixture of tetramers and dimers. In the present work, AAIII dimers were purified and shown to be enzymatically active. Limited trypsinolysis showed two domains of approximately 9 and 25 kDa. The three-dimensional structure of the dimer was studied by electron microscopy of negative stained samples and by single-particle reconstruction. A 16A resolution model of the AAIII dimer was created. It has an unusual, cage-like, structure. A realistic AAIII tetramer model was built from two dimers.

  13. Neptunium(III) copper(I) diselenide.

    PubMed

    Wells, Daniel M; Skanthakumar, S; Soderholm, L; Ibers, James A

    2009-02-11

    The title compound, NpCuSe(2), is the first ternary neptunium transition-metal chalcogenide. It was synthesized from the elements at 873 K in an evacuated fused-silica tube. Single crystals were grown by vapor transport with I(2). NpCuSe(2) crystallizes in the LaCuS(2) structure type and can be viewed as a stacking of layers of CuSe(4) tetra-hedra and of double layers of NpSe(7) monocapped trigonal prisms along [100]. Because there are no Se-Se bonds in the structure, the formal oxidation states of Np/Cu/Se may be assigned as +III/+I/-II, respectively.

  14. Benchmark On Sensitivity Calculation (Phase III)

    SciTech Connect

    Ivanova, Tatiana; Laville, Cedric; Dyrda, James; Mennerdahl, Dennis; Golovko, Yury; Raskach, Kirill; Tsiboulia, Anatoly; Lee, Gil Soo; Woo, Sweng-Woong; Bidaud, Adrien; Patel, Amrit; Bledsoe, Keith C; Rearden, Bradley T; Gulliford, J.

    2012-01-01

    The sensitivities of the keff eigenvalue to neutron cross sections have become commonly used in similarity studies and as part of the validation algorithm for criticality safety assessments. To test calculations of the sensitivity coefficients, a benchmark study (Phase III) has been established by the OECD-NEA/WPNCS/EG UACSA (Expert Group on Uncertainty Analysis for Criticality Safety Assessment). This paper presents some sensitivity results generated by the benchmark participants using various computational tools based upon different computational methods: SCALE/TSUNAMI-3D and -1D, MONK, APOLLO2-MORET 5, DRAGON-SUSD3D and MMKKENO. The study demonstrates the performance of the tools. It also illustrates how model simplifications impact the sensitivity results and demonstrates the importance of 'implicit' (self-shielding) sensitivities. This work has been a useful step towards verification of the existing and developed sensitivity analysis methods.

  15. Disconnecting XRCC1 and DNA ligase III

    PubMed Central

    Katyal, Sachin

    2011-01-01

    DNA strand break repair is essential for the prevention of multiple human diseases, particularly those which feature neuropathology. To further understand the pathogenesis of these syndromes, we recently developed animal models in which the DNA single-strand break repair (SSBR) components, XRCC1 and DNA Ligase III (LIG3), were inactivated in the developing nervous system. Although biochemical evidence suggests that inactivation of XRCC1 and LIG3 should share common biological defects, we found profound phenotypic differences between these two models, implying distinct biological roles for XRCC1 and LIG3 during DNA repair. Rather than a key role in nuclear DNA repair, we found LIG3 function was central to mitochondrial DNA maintenance. Instead, our data indicate that DNA Ligase 1 is the main DNA ligase for XRCC1-mediated DNA repair. These studies refine our understanding of DNA SSBR and the etiology of neurological disease. PMID:21636980

  16. DECIMETRIC TYPE III BURSTS: GENERATION AND PROPAGATION

    SciTech Connect

    Li, B.; Cairns, Iver H.; Robinson, P. A.; Yan, Y. H.

    2011-09-01

    Simulations are presented for decimetric type III radio bursts at 2f{sub p} , where f{sub p} is the local electron plasma frequency. The simulations show that 2f{sub p} radiation can be observed at Earth in two scenarios for the radiation's generation and propagation. In Scenario A, radiation is produced and propagates in warm plasmas in the lower corona that are caused by previous magnetic reconnection outflows and/or chromospheric evaporation. In Scenario B radiation is generated in normal plasmas, then due to its natural directivity pattern and refraction, radiation partly propagates into nearby regions, which are hot because of previous reconnection/evaporation. The profiles of plasma density n{sub e} (r) and electron temperature T{sub e} (r) in the lower corona (r - R{sub sun} {approx}< 100 Mm) are found to be crucial to whether radiation can be produced and escape at observable levels against the effects of free-free absorption, where r is the heliocentric distance. Significantly, the observed wide ranges of radiation properties (e.g., drift rates) require n{sub e} (r) with a large range of scale heights h{sub s} , consistent nonetheless for Scenario B with short observed EUV loops. This is relevant to problems with large h{sub s} inferred from tall EUV loops. The simulations suggest: (1) n{sub e} (r) with small h{sub s} , such as n{sub e} (r){proportional_to}(r - R{sub sun}){sup -2.38} for flaring regions, are unexpectedly common deep in the corona. This result is consistent with recent work on n{sub e} (r) for r {approx} (1.05-2)R{sub sun} extracted from observed metric type IIIs. (2) The dominance of reverse-slope bursts over normal bursts sometimes observed may originate from asymmetric reconnection/acceleration, which favors downgoing beams.

  17. IFU spectroscopy of southern planetary nebulae - III

    NASA Astrophysics Data System (ADS)

    Ali, A.; Dopita, M. A.; Basurah, H. M.; Amer, M. A.; Alsulami, R.; Alruhaili, A.

    2016-10-01

    In this paper, we describe integral field spectroscopic observations of four southern Galactic planetary nebulae (PNe), M3-4, M3-6, Hen2-29 and Hen2-37 covering the spectral range 3400-7000 Å. We derive the ionization structure, the physical conditions, the chemical compositions and the kinematical characteristics of these PNe and find good agreement with previous studies that relied upon the long-slit technique in their co-spatial area. From their chemical compositions as well as their spatial and kinematic characteristics, we determined that Hen2-29 is of the Peimbert type I (He- and N-rich), while the other three are of type II. The strength of the nebular He II line reveals that M3-3, Hen2-29 and Hen2-37 are of mid to high excitation classes while M3-6 is a low-excitation PN. A series of emission-line maps extracted from the data cubes were constructed for each PN to describe its overall structure. These show remarkable morphological diversity. Spatially resolved spectroscopy of M3-6 shows that the recombination lines of C II, C III, C IV and N III are of nebular origin, rather than arising from the central star as had been previously proposed. This result increases doubts regarding the weak emission-line star (WELS) classification raised by Basurah et al. In addition, they reinforce the probability that most genuine cases of WELS arise from irradiation effects in close binary central stars.

  18. Environmentally friendly organic synthesis using bismuth(III) compounds.

    PubMed

    Krabbe, Scott W; Mohan, Ram S

    2012-01-01

    With increasing environmental concerns, the need for environmentally friendly organic synthesis has gained increased importance. In this regard, bismuth(III) compounds are especially attractive as "green" reagents and catalysts for organic synthesis. Bismuth(III) compounds are remarkably nontoxic, relatively air and moisture stable, and easy to handle. The contributions from our laboratory in the last 5 years in the field of applications of bismuth(III) compounds as catalysts are presented.

  19. Wide Bandgap III-Nitride Micro- and Nano-Photonics

    DTIC Science & Technology

    2008-05-05

    AND DATES COVERED Final Report 10/2003 – 10/2007 4. TITLE AND SUBTITLE Wide Bandgap III-Nitride Micro - and Nano -Photonics 5. FUNDING NUMBERS...device issues and to explore potential applications of III-nitrides for UV micro - and nano -photonic devices. The KSU team has achieved 1. n-type...Award No: DAAD19-03-1-0337 Project Title: Wide Bandgap III-Nitride Micro - and Nano -Photonics PI Name: Hongxing Jiang & Jingyu Lin PI Address

  20. ORTHODONTIC TREATMENT ALTERNATIVE TO A CLASS III SUBDIVISION MALOCCLUSION

    PubMed Central

    Janson, Guilherme; de Souza, José Eduardo Prado; Barros, Sérgio Estelita Cavalcante; Andrade, Pedro; Nakamura, Alexandre Yudi

    2009-01-01

    Class III malocclusions are considered one of the most complex and difficult orthodontic problems to diagnose and treat. Skeletal and/or dental asymmetries in patients presenting with Class III malocclusions can worsen the prognosis. Recognizing the dentoalveolar and skeletal characteristics of subdivision malocclusions and their treatment possibilities is essential for a favorable nonsurgical correction. Therefore, this article presents a nonsurgical asymmetric extraction approach to Class III subdivision malocclusion treatment which can significantly improve the occlusal and facial discrepancies. PMID:19668997

  1. Skeletal and dental modifications produced by the Bionator III appliance.

    PubMed

    Garattini, G; Levrini, L; Crozzoli, P; Levrini, A

    1998-07-01

    The therapeutic results of a functional orthopedic treatment with a Balters' Bionator III appliance were evaluated. The sample group included 39 white growing subjects with a dentoskeletal Class III malocclusion. A 2-year study compared results with a control group. The results showed that the Bionator III is effective, especially when the malocclusion is mainly the result of a midfacial deficiency and when there is a hypodivergent growth pattern.

  2. The Nuclear Magnetic Resonance Spectra of Bisphthalocyaninatolanthanide (III).

    DTIC Science & Technology

    1980-06-01

    examined. An effect of a macrocyclic -ring current and an induced shift caused by lanthanide (III) ions were discussed. INTRODUCTION NMR studies of...reported some NMR results of lithium, zinc, 2 and uranyl phthalocyanines. Lanthanide complexes such as acethylacetonato- lanthanide (III) and its...University, College Station, TX 77843 (Received , 1980) The NHR spectra of bisphthalocyaninatolanthanide(III) complexes (La, Nd, Sm, and Eu) have been

  3. Characterization of the biochemical properties of Campylobacter jejuni RNase III

    PubMed Central

    Haddad, Nabila; Saramago, Margarida; Matos, Rute G.; Prévost, Hervé; Arraiano, Cecília M.

    2013-01-01

    Campylobacter jejuni is a foodborne bacterial pathogen, which is now considered as a leading cause of human bacterial gastroenteritis. The information regarding ribonucleases in C. jejuni is very scarce but there are hints that they can be instrumental in virulence mechanisms. Namely, PNPase (polynucleotide phosphorylase) was shown to allow survival of C. jejuni in refrigerated conditions, to facilitate bacterial swimming, cell adhesion, colonization and invasion. In several microorganisms PNPase synthesis is auto-controlled in an RNase III (ribonuclease III)-dependent mechanism. Thereby, we have cloned, overexpressed, purified and characterized Cj-RNase III (C. jejuni RNase III). We have demonstrated that Cj-RNase III is able to complement an Escherichia coli rnc-deficient strain in 30S rRNA processing and PNPase regulation. Cj-RNase III was shown to be active in an unexpectedly large range of conditions, and Mn2+ seems to be its preferred co-factor, contrarily to what was described for other RNase III orthologues. The results lead us to speculate that Cj-RNase III may have an important role under a Mn2+-rich environment. Mutational analysis strengthened the function of some residues in the catalytic mechanism of action of RNase III, which was shown to be conserved. PMID:24073828

  4. Characterization of the biochemical properties of Campylobacter jejuni RNase III.

    PubMed

    Haddad, Nabila; Saramago, Margarida; Matos, Rute G; Prévost, Hervé; Arraiano, Cecília M

    2013-11-25

    Campylobacter jejuni is a foodborne bacterial pathogen, which is now considered as a leading cause of human bacterial gastroenteritis. The information regarding ribonucleases in C. jejuni is very scarce but there are hints that they can be instrumental in virulence mechanisms. Namely, PNPase (polynucleotide phosphorylase) was shown to allow survival of C. jejuni in refrigerated conditions, to facilitate bacterial swimming, cell adhesion, colonization and invasion. In several microorganisms PNPase synthesis is auto-controlled in an RNase III (ribonuclease III)-dependent mechanism. Thereby, we have cloned, overexpressed, purified and characterized Cj-RNase III (C. jejuni RNase III). We have demonstrated that Cj-RNase III is able to complement an Escherichia coli rnc-deficient strain in 30S rRNA processing and PNPase regulation. Cj-RNase III was shown to be active in an unexpectedly large range of conditions, and Mn2+ seems to be its preferred co-factor, contrarily to what was described for other RNase III orthologues. The results lead us to speculate that Cj-RNase III may have an important role under a Mn2+-rich environment. Mutational analysis strengthened the function of some residues in the catalytic mechanism of action of RNase III, which was shown to be conserved.

  5. Antisites in III-V semiconductors: Density functional theory calculations

    SciTech Connect

    Chroneos, A.; Tahini, H. A.; Schwingenschlögl, U.; Grimes, R. W.

    2014-07-14

    Density functional based simulation, corrected for finite size effects, is used to investigate systematically the formation of antisite defects in III-V semiconductors (III = Al, Ga, and In and V = P, As, and Sb). Different charge states are modelled as a function of the Fermi level and under different growth conditions. The formation energies of group III antisites (III{sub V}{sup q}) decrease with increasing covalent radius of the group V atom though not group III radius, whereas group V antisites (V{sub III}{sup q}) show a consistent decrease in formation energies with increase in group III and group V covalent radii. In general, III{sub V}{sup q} defects dominate under III-rich conditions and V{sub III}{sup q} under V-rich conditions. Comparison with equivalent vacancy formation energy simulations shows that while antisite concentrations are always dominant under stoichiometric conditions, modest variation in growth or doping conditions can lead to a significantly higher concentration of vacancies.

  6. Photophysics of Fe(III)-tartrate and Fe(III)-citrate complexes in aqueous solutions

    NASA Astrophysics Data System (ADS)

    Pozdnyakov, Ivan P.; Kolomeets, Alexander V.; Plyusnin, Victor F.; Melnikov, Alexey A.; Kompanets, Victor O.; Chekalin, Sergey V.; Tkachenko, Nikolai; Lemmetyinen, Helge

    2012-03-01

    Femtosecond pump-probe spectroscopy was used to determine the photophysical processes of Fe(III) complexes with citric and tartaric acids ([Fe(Cit)] and [Fe(tart)]+) in aqueous solutions. The excitation of the complexes in the charge transfer bands is followed by formation of an intermediate absorbance decaying with two characteristic times. The shorter time constant (0.2, 0.4 ps) is ascribed to vibrational cooling and solvent relaxation of Frank-Condon excited state of corresponding complex and the second time constant (1.4, 40 ps) is assigned to superposition of internal conversion to the ground state and formation of the long-lived Fe(II) radical complex. The competition of these processes determines the quantum yield of photolysis of Fe(III)-carboxylates.

  7. Phase transitions in i-butylammonium halogenoantimonate(III) and bismuthate(III) crystals

    NASA Astrophysics Data System (ADS)

    Jakubas, R.; Jóźków, J.; Bator, G.; Zaleski, J.; Baran, J.; François, P.

    1997-12-01

    Differential scanning calorimetry, dielectric, thermal expansion, infrared and preliminary X-ray diffraction studies on i-butylammonium halogenoantimonate(III) and bismuthate(III) crystals are reported. All crystals: (i-C 4H 9NH 3) 2BiCl 5, (i-C 4H 9NH 3) 2SbBr 5, (i-C 4H 9NH 3) 3BiCl 6, (i-C 4H 9NH 3) 3Bi 2Br 9, (i-C 4H 9NH 3) 3Sb 2Br 9, show one or more structural phase transitions of first order type. The values of the transition entropies suggest that the most of the phase transitions are of the order-disorder type. The infrared studies confirmed the contribution of the i-butylammonium cations in the phase transition mechanism.

  8. A Qualitative Study of Recovery from Type III-B and III-C Tibial Fractures

    PubMed Central

    Shauver, Melissa S.; Aravind, Maya S.; Chung, Kevin C.

    2011-01-01

    The literature has shown that long-term outcomes for both below-knee amputation and reconstruction following type III-B and III-C tibial fracture are poor. Yet, patients often report satisfaction with their treatment and/or outcomes. The aim of this study is to explore the relationship between patient outcomes and satisfaction after open tibial fractures via qualitative methodology. Twenty patients who were treated for open tibial fractures at one institution were selected using purposeful sampling and interviewed in-person in a semi-structured manner. Data were analyzed using grounded theory methodology. Despite reporting marked physical and psychosocial deficits, participants relayed high satisfaction. We hypothesize that the use adaptive coping techniques successfully reduces stress, which leads to an increase in coping self-efficacy that results in the further use of adaptive coping strategies, culminating in personal growth. This stress reduction and personal growth leads to satisfaction despite poor functional and emotional outcomes. PMID:20948418

  9. Oxalate complexation with aluminum(III) and iron(III) at moderately elevated temperatures

    SciTech Connect

    Tait, C.D.; Janecky, D.R.; Clark, D.L.; Bennett, P.C.

    1992-05-01

    To add to our understanding of the weathering of rocks in organic rich environments such as sedimentary brines and oil field waters, we have examined the temperature dependent complexation of aluminum with oxalate. Raman vibrational studies show that even the association constant for the highly charged Al(ox){sub 3}{sup 3{minus}} unexpectedly increases with moderate temperature increases to 80{degrees}C. To evaluate the potential importance of these Al-oxalate species in complex natural systems, temperature dependent competition experiments Fe(III) and Al(III) for oxalate have been initiated. Similar to aluminum, ferric oxalates show increases in association constants at higher temperatures. In competition experiments, the first association constant for Fe(ox){sup +} increases faster than that for Al(ox){sup +} to 90{degrees}C.

  10. Rhodium(III)- and iridium(III)-catalyzed C7 alkylation of indolines with diazo compounds.

    PubMed

    Ai, Wen; Yang, Xueyan; Wu, Yunxiang; Wang, Xuan; Li, Yuanchao; Yang, Yaxi; Zhou, Bing

    2014-12-22

    A Rh(III)-catalyzed procedure for the C7-selective C-H alkylation of various indolines with α-diazo compounds at room temperature is reported. The advantages of this process are: 1) simple, mild, and pH-neutral reaction conditions, 2) broad substrate scope, 3) complete regioselectivity, 4) no need for an external oxidant, and 5) N2 as the sole byproduct. Furthermore, alkylation and bis-alkylation of carbazoles at the C1 and C8 positions have also been developed. More significantly, for the first time, a successful Ir(III)-catalyzed intermolecular insertion of arene C-H bonds into α-diazo compounds is reported.

  11. Chemical and biological reduction of Mn (III)-pyrophosphate complexes: Potential importance of dissolved Mn (III) as an environmental oxidant

    NASA Astrophysics Data System (ADS)

    Kostka, Joel E.; Luther, George W., III; Nealson, Kenneth H.

    1995-03-01

    Dissolved Mn (III) is a strong oxidant which could play an important role in the biogeochemistry of aquatic environments, but little is known about this form of Mn. Mn(III) was shown to form a stable complex with pyrophosphate which is easily measured by uv-vis spectrophotometry. The Mn(III)-pyrophosphate complex was produced at concentrations of 5 μM to 10 mM Mn at neutral pH. Inorganic electron donors, Fe(II) and sulfide, abiotically reduced Mn(III)-pyrophosphate in seconds with a stoichiometry of 1:1 and near 1:2 reductant:Mn (III), respectively. Shewanella putrefaciens strain MR-1 catalyzed the reduction of Mn(III)-pyrophosphate with formate or lactate as electron donors. Reduction of Mn(III) catalyzed by MR-1 was inhibited under aerobic conditions but only slightly under anaerobic conditions upon addition of the alternate electron acceptor, nitrate. MR-1 catalyzed reduction was also inhibited by metabolic inhibitors including formaldehyde, tetrachlorosalicylanilide (TCS), carbonyl cyanide m-chlorophenylhydrazone (CCCP), 2- n-heptyl-4-hydroxyquinoline N-oxide (HQNO), but not antimycin A. When formate or lactate served as electron donor for Mn(III) reduction, carbon oxidation to CO 2 was coupled to the respiration of Mn (III). Using the incorporation of 3H-leucine into the TCA-insoluble fraction of culture extracts, it was shown that Mn (III) reduction was coupled to protein synthesis in MR-1. These data indicate that Mn (III) complexes may be produced under conditions found in aquatic environments and that the reduction of Mn(III) can be coupled to the cycling of Fe, S, and C.

  12. Cooling effect on the electron states of Si(III)Pd and Si(III)Pt interfaces

    NASA Astrophysics Data System (ADS)

    Abbati, I.; Braicovich, L.; Michelis, B. De; Pennino, U. Del; Valeri, S.

    1980-09-01

    Photoemission and Auger results are given for Si(III)Pd and Si(III)Pt interfaces prepared by depositing 10 ml metal onto cleaved Si(III). Thermal cycling between room temperature and liquid nitrogen temperature originates a reversible effect in the spectra due to metal concentration increase in {Si}/{Pt} and decrease in {Si}/{Pd}. The results are discussed in connection with open problems on Si d-metal interfaces.

  13. Assessment of Fe(III) and Eu(III) complexation by silicate in aqueous solutions

    NASA Astrophysics Data System (ADS)

    Patten, James T.; Byrne, Robert H.

    2017-04-01

    Prior investigations of Eu3+ complexation by silicate have led to predictions that rare earth silicate complexes (REESiO(OH)32+) are the dominant species of REEs in deep waters of the Atlantic and Pacific Oceans. The proposed importance of REE-silicate complexes has been used as a foundation to explain oceanic REE profiles. In the present work, we examine the significance of rare earth element complexation by silicate ions. As one fundamental means of assessing prior depictions of REE-silicate formation constant behavior, our work examines the comparative stability constant behavior of Eu(III) and Fe(III). Plots of Eu(III) complexation constants against Fe(III) formation constants, in conjunction with experimental determinations of FeSiO(OH)32+ formation constants, indicate that previously published EuSiO(OH)32+ formation constants are substantially overestimated. Assessment of prior EuSiO(OH)32+ formation constant determinations reveals that results obtained in the presence and absence of silicic acid polymerization are inconsistent. Much larger EuSiO(OH)32+ formation constants are obtained in the presence of polymeric silica. Reanalysis of complexation results obtained under conditions of minimal silicate polymerization leads to a EuSiO(OH)32+ formation constant that is smaller than previously published estimates by as much as a factor of ∼25. The dramatically reduced magnitude of Siβ1(Eu) relative to previously published results indicates that the role of silicate complexation in oceanic REE cycling is much less significant than previously proposed. The spectrophotometric investigations of FeSiO(OH)32+ formation in the present study yield the first characterization of FeSiO(OH)32+ formation constant behavior as a function of ionic strength:

  14. Synthesis and structural characterization of new dithiocarbamate complexes from Sb(III) and Bi(III)

    SciTech Connect

    Jamaluddin, Nur Amirah; Baba, Ibrahim

    2013-11-27

    Twenty new antimony and bismuth dithiocarbamate complexes which employed ten different type of amines have been successfully synthesized. The synthesized complexes with metal to dithiocarbamate ratio at 1:3. Elemental analysis of the complexes gave the general formula of MCl[S{sub 2}CNR’R”]{sub 2} where M = Sb(III), Bi(III); R’ = methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, benzyl; R” = ethanol, methyl, ethyl, propyl, isopropyl, cyclohexyl, benzyl. The complexes were analysed by IR and NMR spectroscopy. The crystal structure of five-coordinated antimony (III) complex have been determined by X-ray single crystal diffraction. Single crystal X-ray diffraction studies on SbCl[S{sub 2}CN(C{sub 4}H{sub 9})(C{sub 2}H{sub 5})]{sub 2} adopted a triclinic system with a space group P1 with a = 10.0141(8) Å, b = 10.1394(7) Å, c = 11.8665(9) Å, α = 67.960°, β =87.616°, γ = 80.172°.

  15. Interaction of proteins with aluminum(III)-chlorophosphonazo III by resonance Rayleigh scattering method.

    PubMed

    Cui, Zhi-Ping; Liu, Shao-Pu; Liu, Zhong-Fang; Zheng, Hu-Zhi; Hu, Xiao-Li; Xue, Jia-Xing; Tian, Jing

    2014-11-01

    In weak acid medium, aluminum(III) can react with chlorophosphonazo III [CPA(III), H(8)L] to form a 1:1 coordination anion [Al(OH)(H(4)L)](2-). At the same time, proteins such as bovine serum albumin (BSA), lysozyme (Lyso) and human serum albumin (HSA) existed as large cations with positive charges, which further combined with [Al(OH)(H(4)L)](2-) to form a 1:4 chelate. This resulted in significant enhancement of resonance Rayleigh scattering (RRS), second-order scattering (SOS) and frequency doubling scattering (FDS). In this study, we investigated the interaction between [Al(OH)(H(4)L)](2-) and proteins, optimization of the reaction conditions and the spectral characteristics of RRS, SOS and FDS. The maximum RRS wavelengths of different protein systems were located at 357-370 nm. The maximum SOS and FDS wavelengths were located at 546 and 389 nm, respectively. The scattering intensities (ΔI) of the three methods were proportional to the concentration of the proteins, within certain ranges, and the detection limits of the most sensitive RRS method were 2.6-9.3 ng/mL. Moreover, the chelate reaction mechanism or the reasons for the enhancement of RRS were discussed through absorption spectra, fluorescence spectra and circular dichroism (CD) spectra.

  16. Syntheses, structures, and magnetic properties of a family of heterometallic heptanuclear [Cu5Ln2] (Ln = Y(III), Lu(III), Dy(III), Ho(III), Er(III), and Yb(III)) complexes: observation of SMM behavior for the Dy(III) and Ho(III) analogues.

    PubMed

    Chandrasekhar, Vadapalli; Dey, Atanu; Das, Sourav; Rouzières, Mathieu; Clérac, Rodolphe

    2013-03-04

    Sequential reaction of the multisite coordination ligand (LH3) with Cu(OAc)2·H2O, followed by the addition of a rare-earth(III) nitrate salt in the presence of triethylamine, afforded a series of heterometallic heptanuclear complexes containing a [Cu5Ln2] core {Ln = Y(1), Lu(2), Dy(3), Ho(4), Er(5), and Yb(6)}. Single-crystal X-ray crystallography reveals that all the complexes are dicationic species that crystallize with two nitrate anions to compensate the charge. The heptanuclear aggregates in 1-6 are centrosymmetrical complexes, with a hexagonal-like arrangement of six peripheral metal ions (two rare-earth and four copper) around a central Cu(II) situated on a crystallographic inversion center. An all-oxygen environment is found to be present around the rare-earth metal ions, which adopt a distorted square-antiprismatic geometry. Three different Cu(II) sites are present in the heptanuclear complexes: two possess a distorted octahedral coordination sphere while the remaining one displays a distorted square-pyramidal geometry. Detailed static and dynamic magnetic properties of all the complexes have been studied and revealed the single-molecule magnet behavior of the Dy(III) and Ho(III) derivatives.

  17. Structural characterization of Spinacia oleracea trypsin inhibitor III (SOTI-III).

    PubMed

    Glotzbach, Bernhard; Schmelz, Stefan; Reinwarth, Michael; Christmann, Andreas; Heinz, Dirk W; Kolmar, Harald

    2013-01-01

    In recent decades, several canonical serine protease inhibitor families have been classified and characterized. In contrast to most trypsin inhibitors, those from garden four o'clock (Mirabilis jalapa) and spinach (Spinacia oleracea) do not share sequence similarity and have been proposed to form the new Mirabilis serine protease inhibitor family. These 30-40-amino-acid inhibitors possess a defined disulfide-bridge topology and belong to the cystine-knot miniproteins (knottins). To date, no atomic structure of this inhibitor family has been solved. Here, the first structure of S. oleracea trypsin inhibitor III (SOTI-III), in complex with bovine pancreatic trypsin, is reported. The inhibitor was synthesized by solid-phase peptide synthesis on a multi-milligram scale and was assayed to test its inhibitory activity and binding properties. The structure confirmed the proposed cystine-bridge topology. The structural features of SOTI-III suggest that it belongs to a new canonical serine protease inhibitor family with promising properties for use in protein-engineering and medical applications.

  18. Exceptional Oxygen Sensing Properties of New Blue Light-Excitable Highly Luminescent Europium(III) and Gadolinium(III) Complexes

    PubMed Central

    Borisov, Sergey M.; Fischer, Roland; Saf, Robert; Klimant, Ingo

    2016-01-01

    New europium(III) and gadolinium(III) complexes bearing 8-hydroxyphenalenone antenna combine efficient absorption in the blue part of the spectrum and strong emission in polymers at room temperature. The Eu(III) complexes show characteristic red luminescence whereas the Gd(III) dyes are strongly phosphorescent. The luminescence quantum yields are about 20% for the Eu(III) complexes and 50% for the Gd(III) dyes. In contrast to most state-of-the-art Eu(III) complexes the new dyes are quenched very efficiently by molecular oxygen. The luminescence decay times of the Gd(III) complexes exceed 1 ms which ensures exceptional sensitivity even in polymers of moderate oxygen permeability. These sensors are particularly suitable for trace oxygen sensing and may be good substitutes for Pd(II) porphyrins. The photophysical and sensing properties can be tuned by varying the nature of the fourth ligand. The narrow-band emission of the Eu(III) allows efficient elimination of the background light and autofluorescence and is also very attractive for use e.g. in multi-analyte sensors. The highly photostable indicators incorporated in nanoparticles are promising for imaging applications. Due to the straightforward preparation and low cost of starting materials the new dyes represent a promising alternative to the state-of-the-art oxygen indicators particularly for such applications as e.g. food packaging. PMID:27158252

  19. Effect of thrombin and endotoxin on the in vivo metabolism of antithrombin III (AT III) in dogs

    SciTech Connect

    Tanaka, H.; Kobayashi, N.; Maekawa, T.

    1985-11-01

    Effect of thrombin and endotoxin on the metabolism of I-125-labelled canine AT III was studied in mongrel dogs. Under control condition, mean total amount of intravascular AT III with standard deviation was 23.4 +/- 2.4 mg/kg, plasma half life of i.v. injected I-125-AT III was 1.7 +/- 0.2 days, and the fractional catabolic flux (j3x) was 16.3 +/- 1.6 mg/kg/day. The total amount of intra- and extra-vascular AT III was 36.0 +/- 0.34 mg/kg. Neither a 3 hour infusion of a small dose (30 units/kg/hr) of thrombin nor i.v. injection of a large amount of thrombin (5,000-15,000 units/day) with heparin significantly affected AT III metabolism except for a transient decrease in AT III concentration in the latter case, although decrease in plasma fibrinogen concentration and platelet count was observed in both cases. Two injections with 200 micrograms/kg of endotoxin resulted in an evident acceleration of AT III metabolism with significant decrease in the plasma AT III, fibrinogen concentrations and platelet count. More marked changes in AT III metabolism were induced by a single infusion with 1 mg/kg of endotoxin. Changes in hemostatic system coincided with those observed in DIC.

  20. Interactions Between Fe(III)-Oxides and Fe(III)-Phyllosilicates During Microbial Reduction 1: Synthetic Sediments

    SciTech Connect

    Wu, Tao; Kukkadapu, Ravi K.; Griffin, Aron M.; Gorski, Christopher A.; Konishi, Hiromi; Xu, Huifang; Roden, Eric E.

    2015-11-19

    Fe(III)-oxides and Fe(III)-bearing phyllosilicates are the two major iron sources utilized as electron acceptors by dissimilatory iron-reducing bacteria (DIRB) in anoxic soils and sediments. Although there have been many studies of microbial Fe(III)-oxide and Fe(III)-phyllosilicate reduction with both natural and specimen materials, no controlled experimental information is available on the interaction between these two phases when both are available for microbial reduction. In this study, the model DIRB Geobacter sulfurreducens was used to examine the pathways of Fe(III) reduction in Fe(III)-oxide stripped subsurface sediment that was coated with different amounts of synthetic high surface area goethite. Cryogenic (12K) 57Fe Mössbauer spectroscopy was used to determine changes in the relative abundances of Fe(III)-oxide, Fe(III)-phyllosilicate, and phyllosilicate-associated Fe(II) (Fe(II)-phyllosilicate) in bioreduced samples. Analogous Mössbauer analyses were performed on samples from abiotic Fe(II) sorption experiments in which sediments were exposed to a quantity of exogenous soluble Fe(II) (FeCl22H2O) comparable to the amount of Fe(II) produced during microbial reduction. A Fe partitioning model was developed to analyze the fate of Fe(II) and assess the potential for abiotic Fe(II)-catalyzed reduction of Fe(III)-phyllosilicatesilicates. The microbial reduction experiments indicated that although reduction of Fe(III)-oxide accounted for virtually all of the observed bulk Fe(III) reduction activity, there was no significant abiotic electron transfer between oxide-derived Fe(II) and Fe(III)-phyllosilicatesilicates, with 26-87% of biogenic Fe(II) appearing as sorbed Fe(II) in the Fe(II)-phyllosilicate pool. In contrast, the abiotic Fe(II) sorption experiments showed that 41 and 24% of the added Fe(II) engaged in electron transfer to Fe(III)-phyllosilicate surfaces in synthetic goethite-coated and uncoated sediment. Differences in the rate of Fe(II) addition and

  1. Soluble Manganese(III) in the Marine Environment

    NASA Astrophysics Data System (ADS)

    Luther, G. W., III; Oldham, V.; Madison, A.; Tebo, B.; Jones, M.; Jensen, L.; Owings, S.; Mucci, A.; Sundby, B.

    2014-12-01

    Recent field studies have confirmed the presence of soluble manganese(III), which along with Mn(II) passes through a 0.2 μm filter, in suboxic marine waters. Here we applied a spectrophotometric method using a soluble porphyrin as a competitive ligand to calculate the concentrations and kinetics of Mn(II) and Mn(III) recovery. Data will be presented from the suboxic porewaters of the Saint Lawrence estuary, the suboxic and anoxic waters of the Chesapeake Bay and the oxygenated surface waters of a coastal waterway bordered by wetlands and salt marshes in Delaware. Soluble Mn(III) accounts for up to 100% of the dissolved Mn pool with concentrations ranging from the detection limit of 50 nM to 80 μM at the oxic/anoxic interface of the non-sulfidic porewaters from the hemipelagic sediments of the St. Lawrence Estuary. Data indicate weak-ligand complexation of Mn(III) formed from Mn(II) oxidation as well as reduction of MnO2. Complexation of Mn(III) in the anoxic waters of Chesapeake Bay appears stronger as the porphyrin could not outcompete the natural ligands binding Mn(III). Mn(III) complexes were reduced in the presence of hydroxylamine or hydrogen sulfide and detected as Mn(II). Soluble Mn(III) comprised up to 52 % of total dissolved Mn. Profiles over the course of a five day cruise showed that high Mn(III) concentrations (7.3 μM) were observed at low H2S (4.9 μM) whereas low Mn(III) (1.1 μM) was detected at high H2S (40 μM). The presence of Mn(III) in sulfidic waters indicated that it is kinetically stabilized in situ by strong ligands so reduction to Mn(II) was incomplete. One electron reductive dissolution of solid MnO2 particles formed at the oxic-anoxic interface appear to be the source of Mn(III). Lastly, soluble Mn(III) was detected in the oxygenated surface waters of a coastal waterway (salinity ranging from freshwater to 31) bordered by wetlands and salt marshes in Delaware. Soluble Mn(III) made up 0-49 % of the total dissolved Mn (maximum of 1.92

  2. Biochemical and Structural Properties of Mouse Kynurenine Aminotransferase III

    SciTech Connect

    Han, Q.; Robinson, H; Cai, T; Tagle, D; Li, J

    2009-01-01

    Kynurenine aminotransferase III (KAT III) has been considered to be involved in the production of mammalian brain kynurenic acid (KYNA), which plays an important role in protecting neurons from overstimulation by excitatory neurotransmitters. The enzyme was identified based on its high sequence identity with mammalian KAT I, but its activity toward kynurenine and its structural characteristics have not been established. In this study, the biochemical and structural properties of mouse KAT III (mKAT III) were determined. Specifically, mKAT III cDNA was amplified from a mouse brain cDNA library, and its recombinant protein was expressed in an insect cell protein expression system. We established that mKAT III is able to efficiently catalyze the transamination of kynurenine to KYNA and has optimum activity at relatively basic conditions of around pH 9.0 and at relatively high temperatures of 50 to 60C. In addition, mKAT III is active toward a number of other amino acids. Its activity toward kynurenine is significantly decreased in the presence of methionine, histidine, glutamine, leucine, cysteine, and 3-hydroxykynurenine. Through macromolecular crystallography, we determined the mKAT III crystal structure and its structures in complex with kynurenine and glutamine. Structural analysis revealed the overall architecture of mKAT III and its cofactor binding site and active center residues. This is the first report concerning the biochemical characteristics and crystal structures of KAT III enzymes and provides a basis toward understanding the overall physiological role of mammalian KAT III in vivo and insight into regulating the levels of endogenous KYNA through modulation of the enzyme in the mouse brain.

  3. The Porphyromonas gingivalis HmuY haemophore binds gallium(iii), zinc(ii), cobalt(iii), manganese(iii), nickel(ii), and copper(ii) protoporphyrin IX but in a manner different to iron(iii) protoporphyrin IX.

    PubMed

    Wójtowicz, Halina; Bielecki, Marcin; Wojaczyński, Jacek; Olczak, Mariusz; Smalley, John W; Olczak, Teresa

    2013-04-01

    Porphyromonas gingivalis, a major etiological agent of chronic periodontitis, acquires haem from host haemoproteins through a haem transporter HmuR and a haemophore HmuY. The aim of this study was to analyse the binding specificity of HmuY towards non-iron metalloporphyrins which may be employed as antimicrobials to treat periodontitis. HmuY binds gallium(iii), zinc(ii), cobalt(iii), manganese(iii), nickel(ii), and copper(ii) protoporphyrin IX but in a manner different to iron(iii) protoporphyrin IX which uses His(134) and His(166) as axial ligands. The metal ions in Ga(iii)PPIX and Zn(ii)PPIX can accept only His(166) as an axial ligand, whereas nickel(ii) and copper(ii) interact exclusively with His(134). Two forms of pentacoordinate manganese(iii) are present in the Mn(iii)PPIX-HmuY complex since the metal accepts either His(134) or His(166) as a single axial ligand. The cobalt ion is hexacoordinate in the Co(iii)PPIX-HmuY complex and binds His(134) and His(166) as axial ligands; however, some differences in their environments exist. Despite different coordination modes of the central metal ion, gallium(iii), zinc(ii), cobalt(iii), and manganese(iii) protoporphyrin IX bound to the HmuY haemophore cannot be displaced by excess haem. All of the metalloporphyrins examined bind to a P. gingivalis wild-type strain with higher ability compared to a mutant strain lacking a functional hmuY gene, thus corroborating binding of non-iron metalloporphyrins to purified HmuY protein. Our results further clarify the basis of metalloporphyrin acquisition by P. gingivalis and add to understanding of the interactions with porphyrin derivatives which exhibit antimicrobial activity against P. gingivalis.

  4. Blood-brain barrier impairment in MPS III patients

    PubMed Central

    2013-01-01

    Background Mucopolysaccharidosis type III (MPS III) is an autosomal recessive disorder caused by deficiency of a specific enzyme leading to heparan sulfate (HS) accumulation within cells and to eventual progressive cerebral and systemic organ abnormalities. Different enzyme deficiencies comprise the MPS III subcategories (A, B, C, D). Since neuropathological manifestations are common to all MPS III types, determining blood-brain barrier (BBB) condition may be critical to understand potential additional disease mechanisms. Methods We investigated BBB integrity in various brain structures of post-mortem tissues from an eleven year old Caucasian female with MPS III A and from a twenty four year old Caucasian female with MPS III D. Control tissues were obtained post-mortem from three Caucasians without neurological deficits: a twelve year old male, a twenty four year old female, and a twenty seven year old female. BBB capillary ultrastructure (electron microscopy) and capillary functional integrity (IgG leakage, tight junction proteins, and lysosomal accumulation within endothelium) were examined. Results Compromised BBB integrity was found in both MPS III cases. Major study findings were: (1) capillary endothelial and pericyte cell damage; (2) mucopolysaccharide bodies in a majority of endothelial cells and pericytes rupturing cell membranes; (3) severe extracellular edema; (4) IgG microvascular leakage and reductions of occludin and claudin-5 with variations between MPS III types; (5) extensive lysosomal accumulation in capillary endothelium. Conclusions These new findings of BBB structural and functional impairment, although from only two cases, MPS III A and III D, may have implications for disease pathogenesis and should be considered in treatment development for MPS III. PMID:24225396

  5. Biochemical and structural properties of mouse kynurenine aminotransferase III.

    PubMed

    Han, Qian; Robinson, Howard; Cai, Tao; Tagle, Danilo A; Li, Jianyong

    2009-02-01

    Kynurenine aminotransferase III (KAT III) has been considered to be involved in the production of mammalian brain kynurenic acid (KYNA), which plays an important role in protecting neurons from overstimulation by excitatory neurotransmitters. The enzyme was identified based on its high sequence identity with mammalian KAT I, but its activity toward kynurenine and its structural characteristics have not been established. In this study, the biochemical and structural properties of mouse KAT III (mKAT III) were determined. Specifically, mKAT III cDNA was amplified from a mouse brain cDNA library, and its recombinant protein was expressed in an insect cell protein expression system. We established that mKAT III is able to efficiently catalyze the transamination of kynurenine to KYNA and has optimum activity at relatively basic conditions of around pH 9.0 and at relatively high temperatures of 50 to 60 degrees C. In addition, mKAT III is active toward a number of other amino acids. Its activity toward kynurenine is significantly decreased in the presence of methionine, histidine, glutamine, leucine, cysteine, and 3-hydroxykynurenine. Through macromolecular crystallography, we determined the mKAT III crystal structure and its structures in complex with kynurenine and glutamine. Structural analysis revealed the overall architecture of mKAT III and its cofactor binding site and active center residues. This is the first report concerning the biochemical characteristics and crystal structures of KAT III enzymes and provides a basis toward understanding the overall physiological role of mammalian KAT III in vivo and insight into regulating the levels of endogenous KYNA through modulation of the enzyme in the mouse brain.

  6. Type III Radio Burst Duration and SEP Events

    NASA Technical Reports Server (NTRS)

    Gopalswamy, N.; Makela, P.; Xie, H.

    2010-01-01

    Long-duration (>15 min), low-frequency (<14 MHz) type III radio bursts have been reported to be indicative of solar energetic particle events. We measured the durations of type III bursts associated with large SEP events of solar cycle 23. The Type III durations are distributed symmetrically at 1 MHz yielding a mean value of approximately 33 min (median = 32 min) for the large SEP events. When the SEP events with ground level enhancement (GLE,) are considered, the distribution is essentially unchanged (mean = 32 min, median = 30 min). To test the importance of type III bursts in indicating SEP events, we considered a set of six type III bursts from the same active region (AR 10588) whose durations fit the "long duration" criterion. We analyzed the coronal mass ejections (CMEs), flares, and type II radio bursts associated with the type III bursts. The CMEs were of similar speeds and the flares are also of similar size and duration. All but one of the type III bursts was not associated with a type II burst in the metric or longer wavelength domains. The burst without type II burst also lacked a solar energetic particle (SEP) event at energies >25 MeV. The 1-MHz duration of the type III burst (28 rein) is near the median value of type III durations found for gradual SEP events and ground level enhancement (GLE) events. Yet, there was no sign of SEP events. On the other hand, two other type III bursts from the same active region had similar duration but accompanied by WAVES type 11 bursts; these bursts were also accompanied by SEP events detected by SOHO/ERNE. This study suggests that the type III burst duration may not be a good indicator of an SEP event, consistent with the statistical study of Cliver and Ling (2009, ApJ ).

  7. The Nucleosynthetic Signature of Population III

    NASA Astrophysics Data System (ADS)

    Heger, A.; Woosley, S. E.

    2002-03-01

    Growing evidence suggests that the first generation of stars may have been quite massive (~100-300 Msolar). Could these stars have left a distinct nucleosynthetic signature? We explore the nucleosynthesis of helium cores in the mass range MHe=64-133 Msolar, corresponding to main-sequence star masses of approximately 140-260 Msolar. Above MHe=133 Msolar, without rotation and using current reaction rates, a black hole is formed, and no nucleosynthesis is ejected. For lighter helium core masses, ~40-63 Msolar, violent pulsations occur, induced by the pair instability and accompanied by supernova-like mass ejection, but the star eventually produces a large iron core in hydrostatic equilibrium. It is likely that this core, too, collapses to a black hole, thus cleanly separating the heavy-element nucleosynthesis of pair instability supernovae from those of other masses, both above and below. Indeed, black hole formation is a likely outcome for all Population III stars with main-sequence masses between about 25 and 140 Msolar (MHe=9-63 Msolar) as well as those above 260 Msolar. Nucleosynthesis in pair instability supernovae varies greatly with the mass of the helium core. This core determines the maximum temperature reached during the bounce. At the upper range of exploding core masses, a maximum of 57 Msolar of 56Ni is produced, making these the most energetic and the brightest thermonuclear explosions in the universe. Integrating over a distribution of masses, we find that pair instability supernovae produce a roughly solar distribution of nuclei having even nuclear charge (Si, S, Ar, etc.) but are remarkably deficient in producing elements with odd nuclear charge-Na, Al, P, V, Mn, etc. This is because there is no stage of stable post-helium burning to set the neutron excess. Also, essentially no elements heavier than zinc are produced owing to a lack of s- and r-processes. The Fe/Si ratio is quite sensitive to whether the upper bound on the initial mass function is

  8. CONVERSION EXTRACTION DESULFURIZATION (CED) PHASE III

    SciTech Connect

    James Boltz

    2005-03-01

    This project was undertaken to refine the Conversion Extraction Desulfurization (CED) technology to efficiently and economically remove sulfur from diesel fuel to levels below 15-ppm. CED is considered a generic term covering all desulfurization processes that involve oxidation and extraction. The CED process first extracts a fraction of the sulfur from the diesel, then selectively oxidizes the remaining sulfur compounds, and finally extracts these oxidized materials. The Department of Energy (DOE) awarded Petro Star Inc. a contract to fund Phase III of the CED process development. Phase III consisted of testing a continuous-flow process, optimization of the process steps, design of a pilot plant, and completion of a market study for licensing the process. Petro Star and the Degussa Corporation in coordination with Koch Modular Process Systems (KMPS) tested six key process steps in a 7.6-centimeter (cm) (3.0-inch) inside diameter (ID) column at gas oil feed rates of 7.8 to 93.3 liters per hour (l/h) (2.1 to 24.6 gallons per hour). The team verified the technical feasibility with respect to hydraulics for each unit operation tested and successfully demonstrated pre-extraction and solvent recovery distillation. Test operations conducted at KMPS demonstrated that the oxidation reaction converted a maximum of 97% of the thiophenes. The CED Process Development Team demonstrated that CED technology is capable of reducing the sulfur content of light atmospheric gas oil from 5,000-ppm to less than 15-ppm within the laboratory scale. In continuous flow trials, the CED process consistently produced fuel with approximately 20-ppm of sulfur. The process economics study calculated an estimated process cost of $5.70 per product barrel. The Kline Company performed a marketing study to evaluate the possibility of licensing the CED technology. Kline concluded that only 13 refineries harbored opportunity for the CED process. The Kline study and the research team's discussions with

  9. Gd(III)-Gd(III) distance measurements with chirp pump pulses.

    PubMed

    Doll, Andrin; Qi, Mian; Wili, Nino; Pribitzer, Stephan; Godt, Adelheid; Jeschke, Gunnar

    2015-10-01

    The broad EPR spectrum of Gd(III) spin labels restricts the dipolar modulation depth in distance measurements between Gd(III) pairs to a few percent. To overcome this limitation, frequency-swept chirp pulses are utilized as pump pulses in the DEER experiment. Using a model system with 3.4 nm Gd-Gd distance, application of one single chirp pump pulse at Q-band frequencies leads to modulation depths beyond 10%. However, the larger modulation depth is counteracted by a reduction of the absolute echo intensity due to the pump pulse. As supported by spin dynamics simulations, this effect is primarily driven by signal loss to double-quantum coherence and specific to the Gd(III) high spin state of S=7/2. In order to balance modulation depth and echo intensity for optimum sensitivity, a simple experimental procedure is proposed. An additional improvement by 25% in DEER sensitivity is achieved with two consecutive chirp pump pulses. These pulses pump the Gd(III) spectrum symmetrically around the observation position, therefore mutually compensating for dynamical Bloch-Siegert phase shifts at the observer spins. The improved sensitivity of the DEER data with modulation depths on the order of 20% is due to mitigation of the echo reduction effects by the consecutive pump pulses. In particular, the second pump pulse does not lead to additional signal loss if perfect inversion is assumed. Moreover, the compensation of the dynamical Bloch-Siegert phase prevents signal loss due to spatial dependence of the dynamical phase, which is caused by inhomogeneities in the driving field. The new methodology is combined with pre-polarization techniques to measure long distances up to 8.6 nm, where signal intensity and modulation depth become attenuated by long dipolar evolution windows. In addition, the influence of the zero-field splitting parameters on the echo intensity is studied with simulations. Herein, larger sensitivity is anticipated for Gd(III) complexes with zero-field splitting

  10. Gd(III)-Gd(III) distance measurements with chirp pump pulses

    NASA Astrophysics Data System (ADS)

    Doll, Andrin; Qi, Mian; Wili, Nino; Pribitzer, Stephan; Godt, Adelheid; Jeschke, Gunnar

    2015-10-01

    The broad EPR spectrum of Gd(III) spin labels restricts the dipolar modulation depth in distance measurements between Gd(III) pairs to a few percent. To overcome this limitation, frequency-swept chirp pulses are utilized as pump pulses in the DEER experiment. Using a model system with 3.4 nm Gd-Gd distance, application of one single chirp pump pulse at Q-band frequencies leads to modulation depths beyond 10%. However, the larger modulation depth is counteracted by a reduction of the absolute echo intensity due to the pump pulse. As supported by spin dynamics simulations, this effect is primarily driven by signal loss to double-quantum coherence and specific to the Gd(III) high spin state of S = 7/2. In order to balance modulation depth and echo intensity for optimum sensitivity, a simple experimental procedure is proposed. An additional improvement by 25% in DEER sensitivity is achieved with two consecutive chirp pump pulses. These pulses pump the Gd(III) spectrum symmetrically around the observation position, therefore mutually compensating for dynamical Bloch-Siegert phase shifts at the observer spins. The improved sensitivity of the DEER data with modulation depths on the order of 20% is due to mitigation of the echo reduction effects by the consecutive pump pulses. In particular, the second pump pulse does not lead to additional signal loss if perfect inversion is assumed. Moreover, the compensation of the dynamical Bloch-Siegert phase prevents signal loss due to spatial dependence of the dynamical phase, which is caused by inhomogeneities in the driving field. The new methodology is combined with pre-polarization techniques to measure long distances up to 8.6 nm, where signal intensity and modulation depth become attenuated by long dipolar evolution windows. In addition, the influence of the zero-field splitting parameters on the echo intensity is studied with simulations. Herein, larger sensitivity is anticipated for Gd(III) complexes with zero

  11. An Exploration of Challenges Facing Division III Athletic Directors

    ERIC Educational Resources Information Center

    Engbers, Jeffrey L.

    2011-01-01

    The purpose of this study was to establish a basic understanding of the challenges associated with directing athletic programs at NCAA Division III Institutions. Specifically, this study identified the frequency, intensity, and time allocated to common challenges facing the position of the NCAA Division III AD. The challenges were examined using…

  12. Extrapyramidal Symptoms and Medication Use in Mucopolysaccharidosis Type III

    ERIC Educational Resources Information Center

    Tchan, Michel C.; Sillence, David

    2009-01-01

    Background: We report the case of a 16-year-old male with Mucopolysaccharidosis III type A (Sanfilippo syndrome) who was commenced on risperidone for behaviour management. He rapidly developed extrapyramidal symptoms that have not resolved. Method: The medication histories of 20 patients with Mucopolysaccharidosis III seen at a Lysosomal Storage…

  13. 49 CFR 172.440 - RADIOACTIVE YELLOW-III label.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ..., the RADIOACTIVE YELLOW-III label must be as follows: EC02MR91.034 (b) In addition to complying with § 172.407, the background color on the RADIOACTIVE YELLOW-III label must be yellow in the top half...

  14. DSM-III and Norway. History, attitudes and future.

    PubMed

    Malt, U F

    1986-01-01

    The first Norwegian evaluation of the DSM-III system of classification occurred in 1980. A Norwegian translation of the diagnostic criteria was published as part of a textbook in psychiatry in 1984. The Mini DSM-III (Quick reference) was published in 1985. The DSM-III system has been generally well accepted in Norway and is currently used in most research projects besides the ICD system. Several training courses have been arranged for senior psychiatrists and psychologists. Introduction to the DSM-III system is also part of the obligatory training course for psychiatric residents in Norway. From 1987 Norway will use a clinical modification of the ICD-9 system of classification. This modification applies 5 digit coding and includes diagnostic categories found in the DSM-III system but not in the 4 digit ICD-9 version. The DSM-III system of classification represents a major step forward in psychiatric classification. However, revisions are necessary to increase clinical validity. Although Norwegian psychiatry has been inspired by the DSM-III system, Norway remains committed to the ICD systems. The goal must be to make further revisions of the DSM-III and ICD systems, and in the end unite the strengths of these two systems of psychiatric classification.

  15. Vertical III-nitride thin-film power diode

    DOEpatents

    Wierer, Jr., Jonathan; Fischer, Arthur J.; Allerman, Andrew A.

    2017-03-14

    A vertical III-nitride thin-film power diode can hold off high voltages (kV's) when operated under reverse bias. The III-nitride device layers can be grown on a wider bandgap template layer and growth substrate, which can be removed by laser lift-off of the epitaxial device layers grown thereon.

  16. 25 CFR 522.12 - Revocation of class III gaming.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 25 Indians 2 2011-04-01 2011-04-01 false Revocation of class III gaming. 522.12 Section 522.12 Indians NATIONAL INDIAN GAMING COMMISSION, DEPARTMENT OF THE INTERIOR APPROVAL OF CLASS II AND CLASS III ORDINANCES AND RESOLUTIONS SUBMISSION OF GAMING ORDINANCE OR RESOLUTION § 522.12 Revocation of class...

  17. 25 CFR 522.12 - Revocation of class III gaming.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 25 Indians 2 2012-04-01 2012-04-01 false Revocation of class III gaming. 522.12 Section 522.12 Indians NATIONAL INDIAN GAMING COMMISSION, DEPARTMENT OF THE INTERIOR APPROVAL OF CLASS II AND CLASS III ORDINANCES AND RESOLUTIONS SUBMISSION OF GAMING ORDINANCE OR RESOLUTION § 522.12 Revocation of class...

  18. 25 CFR 522.12 - Revocation of class III gaming.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 25 Indians 2 2014-04-01 2014-04-01 false Revocation of class III gaming. 522.12 Section 522.12 Indians NATIONAL INDIAN GAMING COMMISSION, DEPARTMENT OF THE INTERIOR APPROVAL OF CLASS II AND CLASS III ORDINANCES AND RESOLUTIONS SUBMISSION OF GAMING ORDINANCE OR RESOLUTION § 522.12 Revocation of class...

  19. 25 CFR 522.12 - Revocation of class III gaming.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 25 Indians 2 2013-04-01 2013-04-01 false Revocation of class III gaming. 522.12 Section 522.12 Indians NATIONAL INDIAN GAMING COMMISSION, DEPARTMENT OF THE INTERIOR APPROVAL OF CLASS II AND CLASS III ORDINANCES AND RESOLUTIONS SUBMISSION OF GAMING ORDINANCE OR RESOLUTION § 522.12 Revocation of class...

  20. Age Dedifferentiation Hypothesis: Evidence form the WAIS III.

    ERIC Educational Resources Information Center

    Juan-Espinosa, Manuel; Garcia, Luis F.; Escorial, Sergio; Rebollo, Irene; Colom, Roberto; Abad, Francisco J.

    2002-01-01

    Used the Spanish standardization of the Wechsler Adult Intelligence Scale III (WAIS III) (n=1,369) to test the age dedifferentiation hypothesis. Results show no changes in the percentage of variance accounted for by "g" and four group factors when restriction of range is controlled. Discusses an age indifferentation hypothesis. (SLD)