FdC1 and Leaf-Type Ferredoxins Channel Electrons From Photosystem I to Different Downstream Electron Acceptors.

PubMed

Guan, Xiaoqian; Chen, Shuai; Voon, Chia Pao; Wong, Kam-Bo; Tikkanen, Mikko; Lim, Boon L

2018-01-01

Plant-type ferredoxins in Arabidopsis transfer electrons from the photosystem I to multiple redox-driven enzymes involved in the assimilation of carbon, nitrogen, and sulfur. Leaf-type ferredoxins also modulate the switch between the linear and cyclic electron routes of the photosystems. Recently, two novel ferredoxin homologs with extra C-termini were identified in the Arabidopsis genome (AtFdC1, AT4G14890; AtFdC2, AT1G32550). FdC1 was considered as an alternative electron acceptor of PSI under extreme ferredoxin-deficient conditions. Here, we showed that FdC1 could interact with some, but not all, electron acceptors of leaf-type Fds, including the ferredoxin-thioredoxin reductase (FTR), sulfite reductase (SiR), and nitrite reductase (NiR). Photoreduction assay on cytochrome c and enzyme assays confirmed its capability to receive electrons from PSI and donate electrons to the Fd-dependent SiR and NiR but not to the ferredoxin-NADP + oxidoreductase (FNR). Hence, FdC1 and leaf-type Fds may play differential roles by channeling electrons from photosystem I to different downstream electron acceptors in photosynthetic tissues. In addition, the median redox potential of FdC1 may allow it to receive electrons from FNR in non-photosynthetic plastids.

FdC1 and Leaf-Type Ferredoxins Channel Electrons From Photosystem I to Different Downstream Electron Acceptors

PubMed Central

Guan, Xiaoqian; Chen, Shuai; Voon, Chia Pao; Wong, Kam-Bo; Tikkanen, Mikko; Lim, Boon L.

2018-01-01

Plant-type ferredoxins in Arabidopsis transfer electrons from the photosystem I to multiple redox-driven enzymes involved in the assimilation of carbon, nitrogen, and sulfur. Leaf-type ferredoxins also modulate the switch between the linear and cyclic electron routes of the photosystems. Recently, two novel ferredoxin homologs with extra C-termini were identified in the Arabidopsis genome (AtFdC1, AT4G14890; AtFdC2, AT1G32550). FdC1 was considered as an alternative electron acceptor of PSI under extreme ferredoxin-deficient conditions. Here, we showed that FdC1 could interact with some, but not all, electron acceptors of leaf-type Fds, including the ferredoxin-thioredoxin reductase (FTR), sulfite reductase (SiR), and nitrite reductase (NiR). Photoreduction assay on cytochrome c and enzyme assays confirmed its capability to receive electrons from PSI and donate electrons to the Fd-dependent SiR and NiR but not to the ferredoxin-NADP+ oxidoreductase (FNR). Hence, FdC1 and leaf-type Fds may play differential roles by channeling electrons from photosystem I to different downstream electron acceptors in photosynthetic tissues. In addition, the median redox potential of FdC1 may allow it to receive electrons from FNR in non-photosynthetic plastids. PMID:29670639

Differential uptake of photosynthetic and non-photosynthetic proteins by pea root plastids.

PubMed

Yan, Xianxi; Khan, Sultan; Hase, Toshiharu; Emes, Michael J; Bowsher, Caroline G

2006-11-27

The photosynthetic proteins RuBiSCO, ferredoxin I and ferredoxin NADP(+)-oxidoreductase (pFNR) were efficiently imported into isolated pea chloroplasts but not into pea root plastids. By contrast non-photosynthetic ferredoxin III and heterotrophic FNR (hFNR) were efficiently imported into both isolated chloroplasts and root plastids. Chimeric ferredoxin I/III (transit peptide of ferredoxin I attached to the mature region of ferredoxin III) only imported into chloroplasts. Ferredoxin III/I (transit peptide of ferredoxin III attached to the mature region of ferredoxin I) imported into both chloroplasts and root plastids. This suggests that import depends on specific interactions between the transit peptide and the translocon apparatus.

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.

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

PubMed Central

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

2016-01-01

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. PMID:27048649

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.

A Structural Model of a P450-Ferredoxin Complex from Orientation-Selective Double Electron-Electron Resonance Spectroscopy.

PubMed

Bowen, Alice M; Johnson, Eachan O D; Mercuri, Francesco; Hoskins, Nicola J; Qiao, Ruihong; McCullagh, James S O; Lovett, Janet E; Bell, Stephen G; Zhou, Weihong; Timmel, Christiane R; Wong, Luet Lok; Harmer, Jeffrey R

2018-02-21

Cytochrome P450 (CYP) monooxygenases catalyze the oxidation of chemically inert carbon-hydrogen bonds in diverse endogenous and exogenous organic compounds by atmospheric oxygen. This C-H bond oxy-functionalization activity has huge potential in biotechnological applications. Class I CYPs receive the two electrons required for oxygen activation from NAD(P)H via a ferredoxin reductase and ferredoxin. The interaction of Class I CYPs with their cognate ferredoxin is specific. In order to reconstitute the activity of diverse CYPs, structural characterization of CYP-ferredoxin complexes is necessary, but little structural information is available. Here we report a structural model of such a complex (CYP199A2-HaPux) in frozen solution derived from distance and orientation restraints gathered by the EPR technique of orientation-selective double electron-electron resonance (os-DEER). The long-lived oscillations in the os-DEER spectra were well modeled by a single orientation of the CYP199A2-HaPux complex. The structure is different from the two known Class I CYP-Fdx structures: CYP11A1-Adx and CYP101A1-Pdx. At the protein interface, HaPux residues in the [Fe 2 S 2 ] cluster-binding loop and the α3 helix and the C-terminus residue interact with CYP199A2 residues in the proximal loop and the C helix. These residue contacts are consistent with biochemical data on CYP199A2-ferredoxin binding and electron transfer. Electron-tunneling calculations indicate an efficient electron-transfer pathway from the [Fe 2 S 2 ] cluster to the heme. This new structural model of a CYP-Fdx complex provides the basis for tailoring CYP enzymes for which the cognate ferredoxin is not known, to accept electrons from HaPux and display monooxygenase activity.

Improved purification, crystallization and primary structure of pyruvate:ferredoxin oxidoreductase from Halobacterium halobium.

PubMed

Plaga, W; Lottspeich, F; Oesterhelt, D

1992-04-01

An improved purification procedure, including nickel chelate affinity chromatography, is reported which resulted in a crystallizable pyruvate:ferredoxin oxidoreductase preparation from Halobacterium halobium. Crystals of the enzyme were obtained using potassium citrate as the precipitant. The genes coding for pyruvate:ferredoxin oxidoreductase were cloned and their nucleotide sequences determined. The genes of both subunits were adjacent to one another on the halobacterial genome. The derived amino acid sequences were confirmed by partial primary structure analysis of the purified protein. The structural motif of thiamin-diphosphate-binding enzymes was unequivocally located in the deduced amino acid sequence of the small subunit.

Reduction of ferredoxin or oxygen by flavin-based electron bifurcation in Megasphaera elsdenii.

PubMed

Chowdhury, Nilanjan P; Kahnt, Jörg; Buckel, Wolfgang

2015-08-01

Over 50 years ago, it was reported that, in the anaerobic rumen bacterium Megasphaera elsdenii, the reduction of crotonyl-CoA to butyryl-CoA by NADH involved an electron transferring flavoprotein (Etf) as mediator [Baldwin RL, Milligan LP (1964) Biochim Biophys Acta 92, 421-432]. Purification and spectroscopic characterization revealed that this Etf contained 2 FAD, whereas, in the Etfs from aerobic and facultative bacteria, one FAD is replaced by AMP. Recently we detected a similar system in the related anaerobe Acidaminococcus fermentans that differed in the requirement of additional ferredoxin as electron acceptor. The whole process was established as flavin-based electron bifurcation in which the exergonic reduction of crotonyl-CoA by NADH mediated by Etf + butyryl-CoA dehydrogenase (Bcd) was coupled to the endergonic reduction of ferredoxin also by NADH. In the present study, we demonstrate that, under anaerobic conditions, Etf + Bcd from M. elsdenii bifurcate as efficiently as Etf + Bcd from A. fermentans. Under the aerobic conditions used in the study by Baldwin and Milligan and in the presence of catalytic amounts of crotonyl-CoA or butyryl-CoA, however, Etf + Bcd act as NADH oxidase producing superoxide and H2 O2 , whereas ferredoxin is not required. We hypothesize that, during bifurcation, oxygen replaces ferredoxin to yield superoxide. In addition, the formed butyryl-CoA is re-oxidized by a second oxygen molecule to crotonyl-CoA, resulting in a stoichiometry of 2 NADH consumed and 2 H2 O2 formed. As a result of the production of reactive oxygen species, electron bifurcation can be regarded as an Achilles' heel of anaerobes when exposed to air. © 2015 FEBS.

Atomic Resolution Modeling of the Ferredoxin:[FeFe] Hydrogenase Complex from Chlamydomonas reinhardtii

PubMed Central

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

2007-01-01

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 H2 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 H2 evolution, and suggests potential mutagenic strategies to modulate electron flow to HydA2. PMID:17660315

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.

Crystallization and preliminary X-ray diffraction studies of a novel ferredoxin involved in the dioxygenation of carbazole by Novosphingobium sp. KA1

PubMed Central

Umeda, Takashi; Katsuki, Junichi; Usami, Yusuke; Inoue, Kengo; Noguchi, Haruko; Fujimoto, Zui; Ashikawa, Yuji; Yamane, Hisakazu; Nojiri, Hideaki

2008-01-01

Novosphingobium sp. KA1 uses carbazole 1,9a-dioxygenase (CARDO) as the first dioxygenase in its carbazole-degradation pathway. The CARDO of KA1 contains a terminal oxygenase component and two electron-transfer components: ferredoxin and ferredoxin reductase. In contrast to the CARDO systems of other species, the ferredoxin component of KA1 is a putidaredoxin-type protein. This novel ferredoxin was crystallized at 293 K by the hanging-drop vapour-diffusion method using PEG MME 550 as the precipitant under anaerobic conditions. The crystals belong to space group C2221 and diffraction data were collected to a resolution of 1.9 Å (the diffraction limit was 1.6 Å). PMID:18607094

Photosynthetic electron partitioning between [FeFe]-hydrogenase and ferredoxin:NADP+-oxidoreductase (FNR) enzymes in vitro

PubMed Central

Yacoby, Iftach; Pochekailov, Sergii; Toporik, Hila; Ghirardi, Maria L.; King, Paul W.; Zhang, Shuguang

2011-01-01

Photosynthetic water splitting, coupled to hydrogenase-catalyzed hydrogen production, is considered a promising clean, renewable source of energy. It is widely accepted that the oxygen sensitivity of hydrogen production, combined with competition between hydrogenases and NADPH-dependent carbon dioxide fixation are the main limitations for its commercialization. Here we provide evidence that, under the anaerobic conditions that support hydrogen production, there is a significant loss of photosynthetic electrons toward NADPH production in vitro. To elucidate the basis for competition, we bioengineered a ferredoxin-hydrogenase fusion and characterized hydrogen production kinetics in the presence of Fd, ferredoxin:NADP+-oxidoreductase (FNR), and NADP+. Replacing the hydrogenase with a ferredoxin-hydrogenase fusion switched the bias of electron transfer from FNR to hydrogenase and resulted in an increased rate of hydrogen photoproduction. These results suggest a new direction for improvement of biohydrogen production and a means to further resolve the mechanisms that control partitioning of photosynthetic electron transport. PMID:21606330

Coupled ferredoxin and crotonyl coenzyme A (CoA) reduction with NADH catalyzed by the butyryl-CoA dehydrogenase/Etf complex from Clostridium kluyveri.

PubMed

Li, Fuli; Hinderberger, Julia; Seedorf, Henning; Zhang, Jin; Buckel, Wolfgang; Thauer, Rudolf K

2008-02-01

Cell extracts of butyrate-forming clostridia have been shown to catalyze acetyl-coenzyme A (acetyl-CoA)- and ferredoxin-dependent formation of H2 from NADH. It has been proposed that these bacteria contain an NADH:ferredoxin oxidoreductase which is allosterically regulated by acetyl-CoA. We report here that ferredoxin reduction with NADH in cell extracts from Clostridium kluyveri is catalyzed by the butyryl-CoA dehydrogenase/Etf complex and that the acetyl-CoA dependence previously observed is due to the fact that the cell extracts catalyze the reduction of acetyl-CoA with NADH via crotonyl-CoA to butyryl-CoA. The cytoplasmic butyryl-CoA dehydrogenase complex was purified and is shown to couple the endergonic reduction of ferredoxin (E0' = -410 mV) with NADH (E0' = -320 mV) to the exergonic reduction of crotonyl-CoA to butyryl-CoA (E0' = -10 mV) with NADH. The stoichiometry of the fully coupled reaction is extrapolated to be as follows: 2 NADH + 1 oxidized ferredoxin + 1 crotonyl-CoA = 2 NAD+ + 1 ferredoxin reduced by two electrons + 1 butyryl-CoA. The implications of this finding for the energy metabolism of butyrate-forming anaerobes are discussed in the accompanying paper.

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

The CrIIL reduction of [2Fe-2S] ferredoxins and site of attachment of CrIII using 1H NMR and site-directed mutagenesis.

PubMed

Im, S C; Worrall, J A; Liu, G; Aliverti, A; Zanetti, G; Luchinat, C; Bertini, I; Sykes, A G

2000-04-17

with the formation of FeIIFeII...CrIIIL. However, the spinach Glu92Ala (site B) variant undergoes only the first stage of reduction, and it appears that Glu-92 is required for the second stage of reduction to occur. A sample of CrIIIL-modified parsley FeIIIFeIII Fd is fully active as an electron carrier in the NADPH-cytochrome c reductase reaction catalyzed by ferredoxin-NADP+ reductase.

Two functionally distinct NADP+-dependent ferredoxin oxidoreductases maintain the primary redox balance of Pyrococcus furiosus.

PubMed

Nguyen, Diep M N; Schut, Gerrit J; Zadvornyy, Oleg A; Tokmina-Lukaszewska, Monika; Poudel, Saroj; Lipscomb, Gina L; Adams, Leslie A; Dinsmore, Jessica T; Nixon, William J; Boyd, Eric S; Bothner, Brian; Peters, John W; Adams, Michael W W

2017-09-01

Electron bifurcation has recently gained acceptance as the third mechanism of energy conservation in which energy is conserved through the coupling of exergonic and endergonic reactions. A structure-based mechanism of bifurcation has been elucidated recently for the flavin-based enzyme NADH-dependent ferredoxin NADP + oxidoreductase I (NfnI) from the hyperthermophillic archaeon Pyrococcus furiosus. NfnI is thought to be involved in maintaining the cellular redox balance, producing NADPH for biosynthesis by recycling the two other primary redox carriers, NADH and ferredoxin. The P. furiosus genome encodes an NfnI paralog termed NfnII, and the two are differentially expressed, depending on the growth conditions. In this study, we show that deletion of the genes encoding either NfnI or NfnII affects the cellular concentrations of NAD(P)H and particularly NADPH. This results in a moderate to severe growth phenotype in deletion mutants, demonstrating a key role for each enzyme in maintaining redox homeostasis. Despite their similarity in primary sequence and cofactor content, crystallographic, kinetic, and mass spectrometry analyses reveal that there are fundamental structural differences between the two enzymes, and NfnII does not catalyze the NfnI bifurcating reaction. Instead, it exhibits non-bifurcating ferredoxin NADP oxidoreductase-type activity. NfnII is therefore proposed to be a bifunctional enzyme and also to catalyze a bifurcating reaction, although its third substrate, in addition to ferredoxin and NADP(H), is as yet unknown. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

The ferredoxin-thioredoxin reductase variable subunit gene from Anacystis nidulans.

PubMed

Szekeres, M; Droux, M; Buchanan, B B

1991-03-01

The ferredoxin-thioredoxin reductase variable subunit gene of Anacystis nidulans was cloned, and its nucleotide sequence was determined. A single-copy 219-bp open reading frame encoded a protein of 73 amino acid residues, with a calculated Mr of 8,400. The monocistronic transcripts were represented in a 400-base and a less abundant 300-base mRNA form.

The structurally unique photosynthetic Chlorella variabilis NC64A hydrogenase does not interact with plant-type ferredoxins.

PubMed

Engelbrecht, Vera; Rodríguez-Maciá, Patricia; Esselborn, Julian; Sawyer, Anne; Hemschemeier, Anja; Rüdiger, Olaf; Lubitz, Wolfgang; Winkler, Martin; Happe, Thomas

2017-09-01

Hydrogenases from green algae are linked to the photosynthetic electron transfer chain via the plant-type ferredoxin PetF. In this work the [FeFe]-hydrogenase from the Trebouxiophycean alga Chlorella variabilis NC64A (CvHydA1), which in contrast to other green algal hydrogenases contains additional FeS-cluster binding domains, was purified and specific enzyme activities for both hydrogen (H 2 ) production and H 2 oxidation were determined. Interestingly, although C. variabilis NC64A, like many Chlorophycean algal strains, exhibited light-dependent H 2 production activity upon sulfur deprivation, CvHydA1 did not interact in vitro with several plant-type [2Fe-2S]-ferredoxins, but only with a bacterial2[4Fe4S]-ferredoxin. In an electrochemical characterization, the enzyme exhibited features typical of bacterial [FeFe]-hydrogenases (e.g. minor anaerobic oxidative inactivation), as well as of algal enzymes (very high oxygen sensitivity). Copyright © 2017 Elsevier B.V. All rights reserved.

Coupled Ferredoxin and Crotonyl Coenzyme A (CoA) Reduction with NADH Catalyzed by the Butyryl-CoA Dehydrogenase/Etf Complex from Clostridium kluyveri▿ †

PubMed Central

Li, Fuli; Hinderberger, Julia; Seedorf, Henning; Zhang, Jin; Buckel, Wolfgang; Thauer, Rudolf K.

2008-01-01

Cell extracts of butyrate-forming clostridia have been shown to catalyze acetyl-coenzyme A (acetyl-CoA)- and ferredoxin-dependent formation of H2 from NADH. It has been proposed that these bacteria contain an NADH:ferredoxin oxidoreductase which is allosterically regulated by acetyl-CoA. We report here that ferredoxin reduction with NADH in cell extracts from Clostridium kluyveri is catalyzed by the butyryl-CoA dehydrogenase/Etf complex and that the acetyl-CoA dependence previously observed is due to the fact that the cell extracts catalyze the reduction of acetyl-CoA with NADH via crotonyl-CoA to butyryl-CoA. The cytoplasmic butyryl-CoA dehydrogenase complex was purified and is shown to couple the endergonic reduction of ferredoxin (E0′ = −410 mV) with NADH (E0′ = −320 mV) to the exergonic reduction of crotonyl-CoA to butyryl-CoA (E0′ = −10 mV) with NADH. The stoichiometry of the fully coupled reaction is extrapolated to be as follows: 2 NADH + 1 oxidized ferredoxin + 1 crotonyl-CoA = 2 NAD+ + 1 ferredoxin reduced by two electrons + 1 butyryl-CoA. The implications of this finding for the energy metabolism of butyrate-forming anaerobes are discussed in the accompanying paper. PMID:17993531

The ferredoxin-thioredoxin reductase variable subunit gene from Anacystis nidulans.

PubMed Central

Szekeres, M; Droux, M; Buchanan, B B

1991-01-01

The ferredoxin-thioredoxin reductase variable subunit gene of Anacystis nidulans was cloned, and its nucleotide sequence was determined. A single-copy 219-bp open reading frame encoded a protein of 73 amino acid residues, with a calculated Mr of 8,400. The monocistronic transcripts were represented in a 400-base and a less abundant 300-base mRNA form. Images PMID:1705544

Alcelaphine gammaherpesvirus 1-induced malignant catarrhal fever in a Watusi (bos taurus africanus) steer in a North American game park

USDA-ARS?s Scientific Manuscript database

A 10 year-old Watusi (Bos taurus africanus) steer housed at a drive-through game park in Winston, Oregon developed severe clinical illness including: fever, marked nasal discharge, injected scleral and conjunctival membranes, plus oral hemorrhages and erosions. The animal responded poorly to support...

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. Copyright © 2013 Wiley Periodicals, Inc.

Co-localization of glyceraldehyde-3-phosphate dehydrogenase with ferredoxin-NADP reductase in pea leaf chloroplasts

PubMed Central

Negi, Surendra S.; Carol, Andrew A.; Pandya, Shivangi; Braun, Werner; Anderson, Louise E.

2008-01-01

In immunogold double-labeling of pea leaf thin sections with antibodies raised against ferredoxin-NADP reductase (EC 1.18.1.2, FNR) and antibodies directed against the A or B subunits of the NADP-linked glyceraldehyde-3-P dehydrogenase (GAPD) (EC 1.2.1.13), many small and large gold particles were found together over the chloroplasts. Nearest neighbor analysis of the distribution of the gold particles indicates that FNR and the NADP-linked GAPD are co-localized, in situ. This suggests that FNR might carry FADH2 or NADPH from the thylakoid membrane to GAPD, or that ferredoxin might carry electrons to FNR co-localized with GAPD in the stroma. Crystal structures of the spinach enzymes are available. When they are docked computationally, the proteins appear, as modeled, to be able to form at least two different complexes. One involves a single GAPD monomer and an FNR monomer (or dimer). The amino acid residues located at the putative interface are highly conserved on the chloroplastic forms of both enzymes. The other potential complex involves the GAPD A2B2 tetramer and an FNR monomer (or dimer). The interface residues are conserved in this model as well. Ferredoxin is able to interact with FNR in either complex. PMID:17945509

Functional reconstitution of mitochondrial Fe/S cluster synthesis on Isu1 reveals the involvement of ferredoxin.

PubMed

Webert, Holger; Freibert, Sven-Andreas; Gallo, Angelo; Heidenreich, Torsten; Linne, Uwe; Amlacher, Stefan; Hurt, Ed; Mühlenhoff, Ulrich; Banci, Lucia; Lill, Roland

2014-10-31

Maturation of iron-sulphur (Fe/S) proteins involves complex biosynthetic machinery. In vivo synthesis of [2Fe-2S] clusters on the mitochondrial scaffold protein Isu1 requires the cysteine desulphurase complex Nfs1-Isd11, frataxin, ferredoxin Yah1 and its reductase Arh1. The roles of Yah1-Arh1 have remained enigmatic, because they are not required for in vitro Fe/S cluster assembly. Here, we reconstitute [2Fe-2S] cluster synthesis on Isu1 in a reaction depending on Nfs1-Isd11, frataxin, Yah1, Arh1 and NADPH. Unlike in the bacterial system, frataxin is an essential part of Fe/S cluster biosynthesis and is required simultaneously and stoichiometrically to Yah1. Reduced but not oxidized Yah1 tightly interacts with apo-Isu1 indicating a dynamic interaction between Yah1-apo-Isu1. Nuclear magnetic resonance structural studies identify the Yah1-apo-Isu1 interaction surface and suggest a pathway for electron flow from reduced ferredoxin to Isu1. Together, our study defines the molecular function of the ferredoxin Yah1 and its human orthologue FDX2 in mitochondrial Fe/S cluster synthesis.

Energetic basis on interactions between ferredoxin and ferredoxin NADP{sup +} reductase at varying physiological conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kinoshita, Misaki; Kim, Ju Yaen; Kume, Satoshi

In spite of a number of studies to characterize ferredoxin (Fd):ferredoxin NADP{sup +} reductase (FNR) interactions at limited conditions, detailed energetic investigation on how these proteins interact under near physiological conditions and its linkage to FNR activity are still lacking. We herein performed systematic Fd:FNR binding thermodynamics using isothermal titration calorimetry (ITC) at distinct pH (6.0 and 8.0), NaCl concentrations (0–200 mM), and temperatures (19–28 °C) for mimicking physiological conditions in chloroplasts. Energetically unfavorable endothermic enthalpy changes were accompanied by Fd:FNR complexation at all conditions. This energetic cost was compensated by favorable entropy changes, balanced by conformational and hydrational entropy. Increases inmore » the NaCl concentration and pH weakened interprotein affinity due to the less contribution of favorable entropy change regardless of energetic gains from enthalpy changes, suggesting that entropy drove complexation and modulated affinity. Effects of temperature on binding thermodynamics were much smaller than those of pH and NaCl. NaCl concentration and pH-dependent enthalpy and heat capacity changes provided clues for distinct binding modes. Moreover, decreases in the enthalpy level in the Hammond's postulate-based energy landscape implicated kinetic advantages for FNR activity. All these energetic interplays were comprehensively demonstrated by the driving force plot with the enthalpy-entropy compensation which may serve as an energetic buffer against outer stresses. We propose that high affinity at pH 6.0 may be beneficial for protection from proteolysis of Fd and FNR in rest states, and moderate affinity at pH 8.0 and proper NaCl concentrations with smaller endothermic enthalpy changes may contribute to increase FNR activity. - Highlights: • Energetics of Fd:FNR binding were examined by considering physiological conditions. • NaCl and pH affect energetically Fd

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ferraro,D.; Brown, E.; Yu, C.

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 biphenylmore » 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

High stability of a ferredoxin from the hyperthermophilic archaeon A. ambivalens: Involvement of electrostatic interactions and cofactors

PubMed Central

Moczygemba, Charmaine; Guidry, Jesse; Jones, Kathryn L.; Gomes, Cláudio M.; Teixeira, Miguel; Wittung-Stafshede, Pernilla

2001-01-01

The ferredoxin from the thermophilic archaeon Acidianus ambivalens is a small monomeric seven-iron protein with a thermal midpoint (Tm) of 122°C (pH 7). To gain insight into the basis of its thermostability, we have characterized unfolding reactions induced chemically and thermally at various pHs. Thermal unfolding of this ferredoxin, in the presence of various guanidine hydrochloride (GuHCl) concentrations, yields a linear correlation between unfolding enthalpies (ΔH[Tm]) and Tm from which an upper limit for the heat capacity of unfolding (ΔCP) was determined to be 3.15 ± 0.1 kJ/(mole • K). Only by the use of the stronger denaturant guanidine thiocyanate (GuSCN) is unfolding of A. ambivalens ferredoxin at pH 7 (20°C) observed ([GuSCN]1/2 = 3.1 M; ΔGU[H2O] = 79 ± 8 kJ/mole). The protein is, however, less stable at low pH: At pH 2.5, Tm is 64 ± 1°C, and GuHCl-induced unfolding shows a midpoint at 2.3 M (ΔGU[H2O] = 20 ± 1 kJ/mole). These results support that electrostatic interactions contribute significantly to the stability. Analysis of the three-dimensional molecular model of the protein shows that there are several possible ion pairs on the surface. In addition, ferredoxin incorporates two iron–sulfur clusters and a zinc ion that all coordinate deprotonated side chains. The zinc remains bound in the unfolded state whereas the iron–sulfur clusters transiently form linear three-iron species (in pH range 2.5 to 10), which are associated with the unfolded polypeptide, before their complete degradation. PMID:11468351

Bioremediation of petroleum hydrocarbons from crude oil-contaminated soil with the earthworm: Hyperiodrilus africanus.

PubMed

Ekperusi, O A; Aigbodion, F I

2015-12-01

A study on the bioremediation potentials of the earthworm Hyperiodrilus africanus (Beddard) in soil contaminated with crude oil was investigated. Dried and sieved soils were contaminated with 5 ml each of crude oil with replicates and inoculated with earthworms and monitored daily for 12 weeks. Physicochemical parameters such as pH, total organic carbon, sulfate, nitrate, phosphate, sodium, potassium, calcium and magnesium were determined using standard procedures. Total petroleum hydrocarbon (TPH) was determined using atomic absorption spectrophotometer (AAS), while BTEX constituents and earthworms tissues were analyzed using Gas Chromatography with Flame Ionization Detector (GC-FID). The results showed that the earthworm significantly enhanced the physicochemical parameters of the contaminated soil resulting in a decrease of the total organic carbon (56.64 %), sulfate (57.66 %), nitrate (57.69 %), phosphate (57.73 %), sodium (57.69 %), potassium (57.68 %), calcium (57.69 %) and magnesium (57.68 %) except pH (3.90 %) that slightly increased. There was a significant decrease in the TPH (84.99 %), benzene (91.65 %), toluene (100.00 %), ethylbenzene (100.00 %) and xylene (100.00 %). Analyses of the tissues of the earthworm at the end of the experiment showed that the earthworms bioaccumulated/biodegraded 57.35/27.64 % TPH, 38.91/52.73 % benzene, 27.76/72.24 % toluene, 42.16/57.85 % ethylbenzene and 09.62/90.38 % xylene. The results showed that the earthworms H. africanus could be used to bioremediate moderately polluted soil with crude oil contamination in the Niger Delta region of Nigeria.

Amino acid residues in Anabaena ferredoxin crucial to interaction with ferredoxin-NADP+ reductase: site-directed mutagenesis and laser flash photolysis.

PubMed

Hurley, J K; Salamon, Z; Meyer, T E; Fitch, J C; Cusanovich, M A; Markley, J L; Cheng, H; Xia, B; Chae, Y K; Medina, M

1993-09-14

Ferredoxin (Fd) functions in photosynthesis to transfer electrons from photosystem I to ferredoxin-NADP+ reductase (FNR). We have made several site-directed mutants of Anabaena 7120 Fd and have used laser flash photolysis to investigate the effects of these mutations on the kinetics of reduction of oxidized Fd by deazariboflavin semiquinone (dRfH.) and the reduction of oxidized Anabaena FNR by reduced Fd. None of the mutations influenced the second-order rate constant for dRfH. reduction by more than a factor of 2, suggesting that the ability of the [2Fe-2S] cluster to participate in electron transfer was not seriously affected. In contrast, a surface charge reversal mutation, E94K, resulted in a 20,000-fold decrease in the second-order rate constant for electron transfer from Fd to FNR, whereas a similar mutation at an adjacent site, E95K, produced little or no change in reaction rate constant compared to wild-type Fd. Such a dramatic difference between contiguous surface mutations suggests a very precise surface complementarity at the protein-protein interface. Mutations introduced at F65 (F65I and F65A) also decreased the rate constant for the Fd/FNR electron transfer reaction by more than 3 orders of magnitude. Spectroscopic and thermodynamic measurements with both the E94 and F65 mutants indicated that the kinetic differences cannot be ascribed to changes in gross conformation, redox potential, or FNR binding constant but rather reflect the protein-protein interactions that control electron transfer. Several mutations at other sites in the vicinity of E94 and F65 (R42, T48, D68, and D69) resulted in little or no perturbation of the Fd/FNR interaction.(ABSTRACT TRUNCATED AT 250 WORDS)

Three New Abietane-Type Diterpenoids from Plectranthus africanus and Their Antibacterial Activities.

PubMed

Nzogong, Raïssa T; Nganou, Blaise K; Tedonkeu, Alex T; Awouafack, Maurice D; Tene, Mathieu; Ito, Takuya; Tane, Pierre; Morita, Hiroyuki

2018-01-01

Three new abietane-type diterpenoids, plectranthroyleanones A - C (1:  - 3: ), together with five known compounds (4:  - 8: ) were isolated from the methanol extract of the whole plant of Plectranthus africanus using column chromatography techniques. The structures of the new compounds were elucidated using a combination of 1D and 2D NMR and HRESIMS analyses. Compound 1: exhibited weak activities with minimal inhibitory concentration values of 75 µg/mL against gram-positive bacteria, Bacillus subtilis and Staphylococcus aureus , and 150 µg/mL against two gram-negative bacteria, Pseudomonas aeruginosa and Klebsiella pneumoniae , respectively, while 2: and 3: had moderate antibacterial activity against K. pneumoniae with a minimal inhibitory concentration value of 37.5 µg/mL. Georg Thieme Verlag KG Stuttgart · New York.

Critical role of Chlamydomonas reinhardtii ferredoxin-5 in maintaining membrane structure and dark metabolism

PubMed Central

Wittkopp, Tyler M.; Warakanont, Jaruswan; Dubini, Alexandra; Catalanotti, Claudia; Kim, Rick G.; Nowack, Eva C. M.; Mackinder, Luke C. M.; Aksoy, Munevver; Page, Mark Dudley; D’Adamo, Sarah; Saroussi, Shai; Heinnickel, Mark; Johnson, Xenie; Richaud, Pierre; Alric, Jean; Boehm, Marko; Jonikas, Martin C.; Benning, Christoph; Merchant, Sabeeha S.; Posewitz, Matthew C.; Grossman, Arthur R.

2015-01-01

Photosynthetic microorganisms typically have multiple isoforms of the electron transfer protein ferredoxin, although we know little about their exact functions. Surprisingly, a Chlamydomonas reinhardtii mutant null for the ferredoxin-5 gene (FDX5) completely ceased growth in the dark, with both photosynthetic and respiratory functions severely compromised; growth in the light was unaffected. Thylakoid membranes in dark-maintained fdx5 mutant cells became severely disorganized concomitant with a marked decrease in the ratio of monogalactosyldiacylglycerol to digalactosyldiacylglycerol, major lipids in photosynthetic membranes, and the accumulation of triacylglycerol. Furthermore, FDX5 was shown to physically interact with the fatty acid desaturases CrΔ4FAD and CrFAD6, likely donating electrons for the desaturation of fatty acids that stabilize monogalactosyldiacylglycerol. Our results suggest that in photosynthetic organisms, specific redox reactions sustain dark metabolism, with little impact on daytime growth, likely reflecting the tailoring of electron carriers to unique intracellular metabolic circuits under these two very distinct redox conditions. PMID:26627249

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

A model for the catabolism of rhizopine in Rhizobium leguminosarum involves a ferredoxin oxygenase complex and the inositol degradative pathway.

PubMed

Bahar, M; de Majnik, J; Wexler, M; Fry, J; Poole, P S; Murphy, P J

1998-11-01

Rhizopines are nodule-specific compounds that confer an intraspecies competitive nodulation advantage to strains that can catabolize them. The rhizopine (3-O-methyl-scyllo-inosamine, 3-O-MSI) catabolic moc gene cluster mocCABRDE(F) in Rhizobium leguminosarum bv. viciae strain 1a is located on the Sym plasmid. MocCABR are homologous to the mocCABR gene products from Sinorhizobium meliloti. MocD and MocE contain motifs corresponding to a TOL-like oxygenase and a [2Fe-2S] Rieske-like ferredoxin, respectively. The mocF gene encodes a ferredoxin reductase that would complete the oxygenase system, but is not essential for rhizopine catabolism. We propose a rhizopine catabolic model whereby MocB transports rhizopine into the cell and MocDE and MocF (or a similar protein elsewhere in the genome), under the regulation of MocR, act in concert to form a ferredoxin oxygenase system that demethylates 3-O-MSI to form scyllo-inosamine (SI). MocA, an NAD(H)-dependent dehydrogenase, and MocC continue the catabolic process. Compounds formed then enter the inositol catabolic pathway.

Pre-steady-state kinetic studies of redox reactions catalysed by Bacillus subtilis ferredoxin-NADP(+) oxidoreductase with NADP(+)/NADPH and ferredoxin.

PubMed

Seo, Daisuke; Soeta, Takahiro; Sakurai, Hidehiro; Sétif, Pierre; Sakurai, Takeshi

2016-06-01

Ferredoxin-NADP(+) oxidoreductase ([EC1.18.1.2], FNR) from Bacillus subtilis (BsFNR) is a homodimeric flavoprotein sharing structural homology with bacterial NADPH-thioredoxin reductase. Pre-steady-state kinetics of the reactions of BsFNR with NADP(+), NADPH, NADPD (deuterated form) and B. subtilis ferredoxin (BsFd) using stopped-flow spectrophotometry were studied. Mixing BsFNR with NADP(+) and NADPH yielded two types of charge-transfer (CT) complexes, oxidized FNR (FNR(ox))-NADPH and reduced FNR (FNR(red))-NADP(+), both having CT absorption bands centered at approximately 600n m. After mixing BsFNR(ox) with about a 10-fold molar excess of NADPH (forward reaction), BsFNR was almost completely reduced at equilibrium. When BsFNR(red) was mixed with NADP(+), the amount of BsFNR(ox) increased with increasing NADP(+) concentration, but BsFNR(red) remained as the major species at equilibrium even with about 50-fold molar excess NADP(+). In both directions, the hydride-transfer was the rate-determining step, where the forward direction rate constant (~500 s(-1)) was much higher than the reverse one (<10 s(-1)). Mixing BsFd(red) with BsFNR(ox) induced rapid formation of a neutral semiquinone form. This process was almost completed within 1 ms. Subsequently the neutral semiquinone form was reduced to the hydroquinone form with an apparent rate constant of 50 to 70 s(-1) at 10°C, which increased as BsFd(red) increased from 40 to 120 μM. The reduction rate of BsFNR(ox) by BsFd(red) was markedly decreased by premixing BsFNR(ox) with BsFd(ox), indicating that the dissociation of BsFd(ox) from BsFNR(sq) is rate-limiting in the reaction. The characteristics of the BsFNR reactions with NADP(+)/NADPH were compared with those of other types of FNRs. Copyright © 2016 Elsevier B.V. All rights reserved.

Syntrophomonas wolfei Uses an NADH-Dependent, Ferredoxin-Independent [FeFe]-Hydrogenase To Reoxidize NADH

PubMed Central

Losey, Nathaniel A.; Mus, Florence; Peters, John W.; Le, Huynh M.

2017-01-01

ABSTRACT Syntrophomonas wolfei syntrophically oxidizes short-chain fatty acids (four to eight carbons in length) when grown in coculture with a hydrogen- and/or formate-using methanogen. The oxidation of 3-hydroxybutyryl-coenzyme A (CoA), formed during butyrate metabolism, results in the production of NADH. The enzyme systems involved in NADH reoxidation in S. wolfei are not well understood. The genome of S. wolfei contains a multimeric [FeFe]-hydrogenase that may be a mechanism for NADH reoxidation. The S. wolfei genes for the multimeric [FeFe]-hydrogenase (hyd1ABC; SWOL_RS05165, SWOL_RS05170, SWOL_RS05175) and [FeFe]-hydrogenase maturation proteins (SWOL_RS05180, SWOL_RS05190, SWOL_RS01625) were coexpressed in Escherichia coli, and the recombinant Hyd1ABC was purified and characterized. The purified recombinant Hyd1ABC was a heterotrimer with an αβγ configuration and a molecular mass of 115 kDa. Hyd1ABC contained 29.2 ± 1.49 mol of Fe and 0.7 mol of flavin mononucleotide (FMN) per mole enzyme. The purified, recombinant Hyd1ABC reduced NAD+ and oxidized NADH without the presence of ferredoxin. The HydB subunit of the S. wolfei multimeric [FeFe]-hydrogenase lacks two iron-sulfur centers that are present in known confurcating NADH- and ferredoxin-dependent [FeFe]-hydrogenases. Hyd1ABC is a NADH-dependent hydrogenase that produces hydrogen from NADH without the need of reduced ferredoxin, which differs from confurcating [FeFe]-hydrogenases. Hyd1ABC provides a mechanism by which S. wolfei can reoxidize NADH produced during syntrophic butyrate oxidation when low hydrogen partial pressures are maintained by a hydrogen-consuming microorganism. IMPORTANCE Our work provides mechanistic understanding of the obligate metabolic coupling that occurs between hydrogen-producing fatty and aromatic acid-degrading microorganisms and their hydrogen-consuming partners in the process called syntrophy (feeding together). The multimeric [FeFe]-hydrogenase used NADH without the

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.

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.

Direct assignment of the cysteinyl, the slowly exchangeable, and the aromatic ring H nuclear magnetic resonances in clostridial-type ferredoxins. [Clostridium acidi-urici, C. pasteurianum, C. perfringens, Peptococcus aerogenes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Packer, E.L.; Sweeney, W.V.; Rabinowitz, J.C.

1977-04-10

We have directly assigned the /sup 1/H NMR corresponding to the cysteinyl protons, the slowly exchangeable protons, and the aromatic ring protons in the /sup 1/H NMR spectrum of Clostridium acidi-urici ferredoxin by isotopic labeling and /sup 13/C NMR decoupling techniques. We also show that the resonance pattern in the 8- to 20-ppM (from 2,2-dimethyl-2-sialapentanesulfonic acid) region of the /sup 1/H NMR spectra of oxidized Clostridium acidi-urici, Clostridium pasteurianum, Clostridium perfringens, and Peptococcus aerogenes ferredoxins are very similar, and we assign the resonances in this region by analogy with the spectrum of C. acidi-urici ferredoxin. The /sup 1/H NMR spectramore » of the ..beta.. protons of the cysteinyl residues of these ferredoxins differ, however, from the /sup 1/H NMR spectra of equivalent ..beta.. protons of the methylene carbon atoms bonded via a sulfur atom to (4Fe-4S) clusters in synthetic inorganic analogues. In the spectra of the synthetic compounds, the ..beta.. protons appear as a single resonance shifted 10 ppM from its unbonded reference position. In the spectra of oxidized clostridial ferredoxins, the cysteinyl ..beta.. protons appear as a series of at least eight resolved resonances with shifts that range from 6 to 14 ppM, relative to the free amino acid resonance position.« less

H/D exchange mass spectrometry and statistical coupling analysis reveal a role for allostery in a ferredoxin-dependent bifurcating transhydrogenase catalytic cycle.

PubMed

Berry, Luke; Poudel, Saroj; Tokmina-Lukaszewska, Monika; Colman, Daniel R; Nguyen, Diep M N; Schut, Gerrit J; Adams, Michael W W; Peters, John W; Boyd, Eric S; Bothner, Brian

2018-01-01

Recent investigations into ferredoxin-dependent transhydrogenases, a class of enzymes responsible for electron transport, have highlighted the biological importance of flavin-based electron bifurcation (FBEB). FBEB generates biomolecules with very low reduction potential by coupling the oxidation of an electron donor with intermediate potential to the reduction of high and low potential molecules. Bifurcating systems can generate biomolecules with very low reduction potentials, such as reduced ferredoxin (Fd), from species such as NADPH. Metabolic systems that use bifurcation are more efficient and confer a competitive advantage for the organisms that harbor them. Structural models are now available for two NADH-dependent ferredoxin-NADP + oxidoreductase (Nfn) complexes. These models, together with spectroscopic studies, have provided considerable insight into the catalytic process of FBEB. However, much about the mechanism and regulation of these multi-subunit proteins remains unclear. Using hydrogen/deuterium exchange mass spectrometry (HDX-MS) and statistical coupling analysis (SCA), we identified specific pathways of communication within the model FBEB system, Nfn from Pyrococus furiosus, under conditions at each step of the catalytic cycle. HDX-MS revealed evidence for allosteric coupling across protein subunits upon nucleotide and ferredoxin binding. SCA uncovered a network of co-evolving residues that can provide connectivity across the complex. Together, the HDX-MS and SCA data show that protein allostery occurs across the ensemble of iron‑sulfur cofactors and ligand binding sites using specific pathways that connect domains allowing them to function as dynamically coordinated units. Copyright © 2017 Elsevier B.V. All rights reserved.

Towards a mechanistic and physiological understanding of a ferredoxin disulfide reductase from the domains Archaea and Bacteria.

PubMed

Prakash, Divya; Walters, Karim A; Martinie, Ryan J; McCarver, Addison C; Kumar, Adepu K; Lessner, Daniel J; Krebs, Carsten; Golbeck, John H; Ferry, James G

2018-05-02

Disulfide reductases reduce other proteins and are critically important for cellular redox signaling and homeostasis. Methanosarcina acetivorans is a methane-producing microbe from the domain Archaea that produces a ferredoxin:disulfide reductase (FDR) for which the crystal structure has been reported, yet its biochemical mechanism and physiological substrates are unknown. FDR and the extensively characterized plant-type ferredoxin:thioredoxin reductase (FTR) belong to a distinct class of disulfide reductases that contain a unique active-site [4Fe-4S] cluster. The results reported here support a mechanism for FDR similar to that reported for FTR with notable exceptions. Unlike FTR, FDR contains a rubredoxin [1Fe-0S] center postulated to mediate electron transfer from ferredoxin to the active-site [4Fe-4S] cluster.  UV-Vis, EPR and Mӧssbauer spectroscopic data indicated that two-electron reduction of the active-site disulfide in FDR involves a one-electron-reduced [4Fe-4S]1+ intermediate previously hypothesized for FTR. Our results support a role for an active-site tyrosine in FDR that occupies the equivalent position of an essential histidine in the active-site of FTR. Of note, one of seven Trxs encoded in the genome (Trx5) and methanoredoxin, a glutaredoxin-like enzyme from M. acetivorans, were reduced by FDR advancing the physiological understanding of FDRs role in the redox metabolism of methanoarchaea. Finally, bioinformatics analyses show FDR homologs are widespread in diverse microbes from the domain Bacteria. Published under license by The American Society for Biochemistry and Molecular Biology, Inc.

Crystallization and preliminary X-ray diffraction studies of the ferredoxin reductase component in the Rieske nonhaem iron oxygenase system carbazole 1,9a-dioxygenase

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ashikawa, Yuji; Uchimura, Hiromasa; Fujimoto, Zui

2007-06-01

The NAD(P)H:ferredoxin oxidoreductase in carbazole 1,9a-dioxygenase from Janthinobacterium sp. J3 was crystallized and diffraction data were collected to 2.60 Å resolution. Carbazole 1,9a-dioxygenase (CARDO), which consists of an oxygenase component (CARDO-O) and the electron-transport components ferredoxin (CARDO-F) and ferredoxin reductase (CARDO-R), catalyzes dihydroxylation at the C1 and C9a positions of carbazole. CARDO-R was crystallized at 277 K using the hanging-drop vapour-diffusion method with the precipitant PEG 8000. Two crystal types (types I and II) were obtained. The type I crystal diffracted to a maximum resolution of 2.80 Å and belonged to space group P4{sub 2}2{sub 1}2, with unit-cell parameters amore » = b = 158.7, c = 81.4 Å. The type II crystal was obtained in drops from which type I crystals had been removed; it diffracted to 2.60 Å resolution and belonged to the same space group, with unit-cell parameters a = b = 161.8, c = 79.5 Å.« less

Ferredoxin is involved in secretion of cytotoxic necrotizing factor 1 across the cytoplasmic membrane in Escherichia coli K1.

PubMed

Yu, Hao; Kim, Kwang Sik

2010-02-01

We previously showed that cytotoxic necrotizing factor 1 (CNF1) contributes to Escherichia coli K1 invasion of human brain microvascular endothelial cells (HBMEC) and interacts with the receptor on the surface of HBMEC. CNF1 is the cytoplasmic protein, and it remains incompletely understood how CNF1 is secreted across the inner and outer membranes in E. coli K1. In order to investigate the genetic determinants for secretion of CNF1 in E. coli K1, we performed Tn5 mutagenesis screening by applying beta-lactamase as a reporter to monitor secretion of CNF1. We identified a Tn5 mutant that exhibited no beta-lactamase activity in the culture supernatant and in which the mutated gene encodes a ferredoxin gene (fdx). In the fdx deletion mutant, there was no evidence of translocation of CNF1 into HBMEC. Western blot analysis of the fdx deletion mutant revealed that ferredoxin is involved in translocation of CNF1 across the cytoplasmic membrane. The fdx mutant exhibited significantly decreased invasion of HBMEC, similar to the decreased HBMEC invasion observed with the CNF1 mutant. The failures to secrete CNF1 and invade HBMEC of the fdx mutant were restored to the levels of the parent strain by complementation with fdx. These findings demonstrate for the first time that ferredoxin is involved in secretion of CNF1 across the inner membrane in meningitis-causing E. coli K1.

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

USDA-ARS?s Scientific Manuscript database

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...

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

Homology modeling and in silico site directed mutagenesis of pyruvate ferredoxin oxidoreductase from Clostridium thermocellum.

PubMed

Saranyah, Kannuchamy; Kalva, Sukesh; Mukund, Nisha; Singh, Sanjeev Kumar; Saleena, Lilly M

2015-01-01

Pyruvate ferredoxin oxidoreductase is the crucial enzyme that involves in bioethanol synthesis pathway of Clostridium thermocellum. It is an ethanologenic organism but has been investigated less on its enzyme structure. The amino acid sequence of Pyruvate ferredoxin oxidoreductase was derived from UNIPROT and the screened crystal structure was taken as the template for homology modeling using MODELLER 9V11. The model was loop refined and was validated using RMSD, ProSA and PROCHECK. The docking and per residue interaction studies were carried out to elucidate the interaction energies of amino acid residues with pyruvate. To enhance the binding of pyruvate with the enzyme, mutation studies were carried out by replacing Thr31 as it had a less interaction energy. Out of 10 mutants, T31N, T31Q and T31G were selected using potential energy and the residual energy calculations. Five nanoseconds explicit MD simulations were run for apo, wild type and mutants T31N, T31Q and T31G using Desmond. RMSD, RMSF, distance plots and H-bonds analysis proved T31G to be a favorable mutant for binding of pyruvate. Thus, modeling PFOR would help in profound understanding of its structural clefts and mutation studies would aid in improving the enzyme efficiency.

Spectroscopic and Redox Studies of Valence-Delocalized [Fe2S2]+ Centers in Thioredoxin-Like Ferredoxins

PubMed Central

Subramanian, Sowmya; Duin, Evert C.; Fawcett, Sarah E. J.; Armstrong, Fraser A.; Meyer, Jacques; Johnson, Michael K.

2015-01-01

Reduced forms of the C56S and C60S variants of the thioredoxin-like Clostridium pasteurianum [Fe2S2] ferredoxin (CpFd) provide the only known examples of valence-delocalized [Fe2S2]+ clusters, which constitute a fundamental building block of all higher nuclearity Fe-S clusters. In this work, we have revisited earlier work on the CpFd variants and carried out redox and spectroscopic studies on the [Fe2S2]2+,+ centers in wild-type and equivalent variants of the highly homologous and structurally characterized Aquifex aeolicus ferredoxin 4 (AaeFd4) using EPR, UV-visible-NIR absorption, CD and variable-temperature MCD, and protein-film electrochemistry. The results indicate that the [Fe2S2]+ centers in the equivalent AaeFd4 and CpFd variants reversibly interconvert between similar valence-localized S = 1/2 and valence-delocalized S = 9/2 forms as a function of pH, with pKa values in the range 8.3-9.0, due to protonation of the coordinated serinate residue. However, freezing high-pH samples results in partial or full conversion from valence-delocalized S = 9/2 to valence-localized S = 1/2 [Fe2S2]+ clusters. MCD saturation magnetization data for valence-delocalized S = 9/2 [Fe2S2]+ centers facilitated determination of transition polarizations and thereby assignments of low-energy MCD bands associated with the Fe−Fe interaction. The assignments provide experimental assessment of the double exchange parameter, B, for valence-delocalized [Fe2S2]+ centers and demonstrate that variable-temperature MCD spectroscopy provides a means of detecting and investigating the properties of valence-delocalized S = 9/2 [Fe2S2]+ fragments in higher nuclearity Fe-S clusters. The origin of valence delocalization in thioredoxin-like ferredoxin Cys-to-Ser variants and Fe-S clusters in general is discussed in light of these results. PMID:25790339

Allostery in the ferredoxin protein motif does not involve a conformational switch.

PubMed

Nechushtai, Rachel; Lammert, Heiko; Michaeli, Dorit; Eisenberg-Domovich, Yael; Zuris, John A; Luca, Maria A; Capraro, Dominique T; Fish, Alex; Shimshon, Odelia; Roy, Melinda; Schug, Alexander; Whitford, Paul C; Livnah, Oded; Onuchic, José N; Jennings, Patricia A

2011-02-08

Regulation of protein function via cracking, or local unfolding and refolding of substructures, is becoming a widely recognized mechanism of functional control. Oftentimes, cracking events are localized to secondary and tertiary structure interactions between domains that control the optimal position for catalysis and/or the formation of protein complexes. Small changes in free energy associated with ligand binding, phosphorylation, etc., can tip the balance and provide a regulatory functional switch. However, understanding the factors controlling function in single-domain proteins is still a significant challenge to structural biologists. We investigated the functional landscape of a single-domain plant-type ferredoxin protein and the effect of a distal loop on the electron-transfer center. We find the global stability and structure are minimally perturbed with mutation, whereas the functional properties are altered. Specifically, truncating the L1,2 loop does not lead to large-scale changes in the structure, determined via X-ray crystallography. Further, the overall thermal stability of the protein is only marginally perturbed by the mutation. However, even though the mutation is distal to the iron-sulfur cluster (∼20 Å), it leads to a significant change in the redox potential of the iron-sulfur cluster (57 mV). Structure-based all-atom simulations indicate correlated dynamical changes between the surface-exposed loop and the iron-sulfur cluster-binding region. Our results suggest intrinsic communication channels within the ferredoxin fold, composed of many short-range interactions, lead to the propagation of long-range signals. Accordingly, protein interface interactions that involve L1,2 could potentially signal functional changes in distal regions, similar to what is observed in other allosteric systems.

Effect of two intermediate electron donors, NADPH and FADH(2), on Spirulina Delta (6)-desaturase co-expressed with two different immediate electron donors, cytochrome b (5) and ferredoxin, in Escherichia coli.

PubMed

Kurdrid, Pavinee; Subudhi, Sanjukta; Cheevadhanarak, Supapon; Tanticharoen, Morakot; Hongsthong, Apiradee

2007-12-01

When the gene desD encoding Spirulina Delta(6)-desaturase was heterologously expressed in E. coli, the enzyme was expressed without the ability to function. However, when this enzyme was co-expressed with an immediate electron donor, i.e. the cytochrome b (5) domain from Mucor rouxii, the results showed the production of GLA (gamma-linolenic acid), the product of the reaction catalyzed by Delta(6)-desaturase. The results revealed that in E. coli cells, where cytochrome b (5) is absent and ferredoxin, a natural electron donor of Delta(6)-desaturase, is present at a very low level, the cytochrome b (5) domain can complement for the function of ferredoxin in the host cells. In the present study, the Spirulina-ferredoxin gene was cloned and co-expressed with the Delta(6)-desaturase in E. coli. In comparison to the co-expression of cytochrome b ( 5 ) with the Delta(6)-desaturase, the co-expression with ferredoxin did not cause any differences in the GLA level. Moreover, the cultures containing the Delta(6)-desaturase co-expressed with cytochrome b (5) and ferredoxin were exogenously supplied with the intermediate electron donors, NADPH (nicotinamide adenine dinucleotide phosphate, reduced form) and FADH(2) (flavin adenine dinucleotide, reduced form), respectively. The GLA level in these host cells increased drastically, by approximately 50%, compared to the cells without the intermediate electron donors. The data indicated that besides the level of immediate electron donors, the level of intermediate electron donors is also critical for GLA production. Therefore, if the pools of the immediate and intermediate electron donors in the cells are manipulated, the GLA production in the heterologous host will be affected.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matsuzawa, Jun; Aikawa, Hiroki; Umeda, Takashi

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{submore » 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%.« less

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.

Brief communication: predatory bird damage to the Taung type-skull of Australopithecus africanus Dart 1925.

PubMed

Berger, Lee R

2006-10-01

In this issue of the Journal, McGraw et al. ([2006] Am. J. Phys. Anthropol. 000:00-00) present new data on the taphonomic signature of bone assemblages accumulated by crowned hawk eagles (Stephanoaetus coronatus), including characteristic talon damage to the inferior orbits of primates preyed upon by these birds. Reexamination of the Taung juvenile hominin specimen (the type specimen of Australopithecus africanus Dart 1925) reveals previously undescribed damage to the orbital floors that is nearly identical to that seen in the crania of monkeys preyed upon by crowned hawk eagles (as reported by McGraw et al., this issue). This new evidence, along with previously described aspects of the nonhominin bone assemblage from Taung and damage to the neurocranium of the hominin specimen itself, strongly supports the hypothesis that a bird of prey was an accumulating agent at Taung, and that the Taung child itself was the victim of a bird of prey.

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

USDA-ARS?s Scientific Manuscript database

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...

Increasing the electron-transfer ability of Cyanidioschyzon merolae ferredoxin by a one-point mutation – A high resolution and Fe-SAD phasing crystal structure analysis of the Asp58Asn mutant

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ueno, Yuko; Matsumoto, Takashi; Yamano, Akihito

2013-07-12

Highlights: •A single amino acid change on the ferredoxin surface affects electron transfer. •Precise positions of amide atoms were located utilizing no prior structural data. •Ultra high resolution and SAD phasing may be used for bias-free model building. -- Abstract: Cyanidioschyzon merolae (Cm) is a single cell red algae that grows in rather thermophilic (40–50 °C) and acidic (pH 1–3) conditions. Ferredoxin (Fd) was purified from this algae and characterized as a plant-type [2Fe–2S] Fd by physicochemical techniques. A high resolution (0.97 Å) three-dimensional structure of the CmFd D58N mutant molecule has been determined using the Fe-SAD phasing method tomore » clarify the precise position of the Asn58 amide, as this substitution increases the electron-transfer ability relative to wild-type CmFd by a factor of 1.5. The crystal structure reveals an electro-positive surface surrounding Asn58 that may interact with ferredoxin NADP{sup +} reductase or cytochrome c.« less

Purification and Molecular Characterization of the Tungsten-Containing Formaldehyde Ferredoxin Oxidoreductase from the Hyperthermophilic Archaeon Pyrococcus furiosus: the Third of a Putative Five-Member Tungstoenzyme Family

PubMed Central

Roy, Roopali; Mukund, Swarnalatha; Schut, Gerrit J.; Dunn, Dianne M.; Weiss, Robert; Adams, Michael W. W.

1999-01-01

Pyrococcus furiosus is a hyperthermophilic archaeon which grows optimally near 100°C by fermenting peptides and sugars to produce organic acids, CO2, and H2. Its growth requires tungsten, and two different tungsten-containing enzymes, aldehyde ferredoxin oxidoreductase (AOR) and glyceraldehyde-3-phosphate ferredoxin oxidoreductase (GAPOR), have been previously purified from P. furiosus. These two enzymes are thought to function in the metabolism of peptides and carbohydrates, respectively. A third type of tungsten-containing enzyme, formaldehyde ferredoxin oxidoreductase (FOR), has now been characterized. FOR is a homotetramer with a mass of 280 kDa and contains approximately 1 W atom, 4 Fe atoms, and 1 Ca atom per subunit, together with a pterin cofactor. The low recovery of FOR activity during purification was attributed to loss of sulfide, since the purified enzyme was activated up to fivefold by treatment with sulfide (HS−) under reducing conditions. FOR uses P. furiosus ferredoxin as an electron acceptor (Km = 100 μM) and oxidizes a range of aldehydes. Formaldehyde (Km = 15 mM for the sulfide-activated enzyme) was used in routine assays, but the physiological substrate is thought to be an aliphatic C5 semi- or dialdehyde, e.g., glutaric dialdehyde (Km = 1 mM). Based on its amino-terminal sequence, the gene encoding FOR (for) was identified in the genomic database, together with those encoding AOR and GAPOR. The amino acid sequence of FOR corresponded to a mass of 68.7 kDa and is highly similar to those of the subunits of AOR (61% similarity and 40% identity) and GAPOR (50% similarity and 23% identity). The three genes are not linked on the P. furiosus chromosome. Two additional (and nonlinked) genes (termed wor4 and wor5) that encode putative tungstoenzymes with 57% (WOR4) and 56% (WOR5) sequence similarity to FOR were also identified. Based on sequence motif similarities with FOR, both WOR4 and WOR5 are also proposed to contain a tungstobispterin site and

Ferredoxin-thioredoxin reductase, an iron-sulfur enzyme linking light to enzyme regulation in oxygenic photosynthesis: purification and properties of the enzyme from C3, C4, and cyanobacterial species.

PubMed

Droux, M; Jacquot, J P; Miginac-Maslow, M; Gadal, P; Huet, J C; Crawford, N A; Yee, B C; Buchanan, B B

1987-02-01

Ferredoxin-thioredoxin reductase (FTR), an enzyme involved in the light regulation of chloroplast enzymes, was purified to homogeneity from leaves of spinach (a C3 plant) and corn (a C4 plant) and from cells of a cyanobacterium (Nostoc muscorum). The enzyme is a yellowish brown iron-sulfur protein, containing four nonheme iron and labile sulfide groups, that catalyzes the activation of NADP-malate dehydrogenase and fructose 1,6-bisphosphatase in the presence of ferredoxin and of thioredoxin m and f, respectively. FTR is synonymous with the protein earlier called ferralterin. FTR showed an Mr of about 30,000 (determined by sedimentation equilibrium ultracentrifugation, amino acid composition, gel filtration, and gradient gel electrophoresis) and was composed of two dissimilar subunits (as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis). One of the FTR subunits from each source was similar both in Mr (about 13,000) and immunological properties, while the other subunit (of variable molecular weight) was characteristic of a particular organism. The similar subunit contained a disulfide group that was rapidly reduced by a dithiol (dithiothreitol) but not by monothiols (2-mercaptoethanol or reduced glutathione). Homogeneous FTR formed a tight noncovalent complex with ferredoxin on affinity columns. The basis for the structural variation in the different FTR enzymes remains to be determined.

Insight Into the Radical Mechanism of Phycocyanobilin-Ferredoxin Oxidoreductase (Pcya) Revealed By X-Ray Crystallography And Biochemical Measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tu, S.-L.; Rockwell, N.; Lagarias, J.C.

2007-07-13

The X-ray crystal structure of the substrate-free form of phycocyanobilin (PCB)-ferredoxin oxidoreductase (PcyA; EC 1.3.7.5) from the cyanobacterium Nostoc sp. PCC7120 has been solved at 2.5 angstrom resolution. A comparative analysis of this structure with those recently reported for substrate-bound and substrate-free forms of PcyA from the cyanobacterium Synechocystis sp. PCC6803 (Hagiwara et al. (2006) Proc. Natl. Acad. Sci. U.S.A. 103, 27-32; Hagiwara et al. (2006) FEBS Lett. 580, 3823-3828) provides a compelling picture of substrate-induced changes in the PcyA enzyme and the chemical basis of PcyA's catalytic activity. On the basis of these structures and the biochemical analysis ofmore » site-directed mutants of Nostoc PcyA, including mutants reported in recent studies (Tu et al. (2006) J. Biol. Chem. 281, 3127-3136) as well as mutants described in this study, a revised mechanism for the PcyA-mediated four-electron reduction of biliverdin IX{alpha} to 3E/3Z-phycocyanobilin via enzyme-bound bilin radical intermediates is proposed. The mechanistic insight of these studies, along with homology modeling, have provided new insight into the catalytic mechanisms of other members of the ferredoxin-dependent bilin reductase family that are widespread in oxygenic photosynthetic organisms.« less

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

Flavin-Based Electron Bifurcation, Ferredoxin, Flavodoxin, and Anaerobic Respiration With Protons (Ech) or NAD+ (Rnf) as Electron Acceptors: A Historical Review

PubMed Central

Buckel, Wolfgang; Thauer, Rudolf K.

2018-01-01

Flavin-based electron bifurcation is a newly discovered mechanism, by which a hydride electron pair from NAD(P)H, coenzyme F420H2, H2, or formate is split by flavoproteins into one-electron with a more negative reduction potential and one with a more positive reduction potential than that of the electron pair. Via this mechanism microorganisms generate low- potential electrons for the reduction of ferredoxins (Fd) and flavodoxins (Fld). The first example was described in 2008 when it was found that the butyryl-CoA dehydrogenase-electron-transferring flavoprotein complex (Bcd-EtfAB) of Clostridium kluyveri couples the endergonic reduction of ferredoxin (E0′ = −420 mV) with NADH (−320 mV) to the exergonic reduction of crotonyl-CoA to butyryl-CoA (−10 mV) with NADH. The discovery was followed by the finding of an electron-bifurcating Fd- and NAD-dependent [FeFe]-hydrogenase (HydABC) in Thermotoga maritima (2009), Fd-dependent transhydrogenase (NfnAB) in various bacteria and archaea (2010), Fd- and H2-dependent heterodisulfide reductase (MvhADG-HdrABC) in methanogenic archaea (2011), Fd- and NADH-dependent caffeyl-CoA reductase (CarCDE) in Acetobacterium woodii (2013), Fd- and NAD-dependent formate dehydrogenase (HylABC-FdhF2) in Clostridium acidi-urici (2013), Fd- and NADP-dependent [FeFe]-hydrogenase (HytA-E) in Clostridium autoethanogrenum (2013), Fd(?)- and NADH-dependent methylene-tetrahydrofolate reductase (MetFV-HdrABC-MvhD) in Moorella thermoacetica (2014), Fd- and NAD-dependent lactate dehydrogenase (LctBCD) in A. woodii (2015), Fd- and F420H2-dependent heterodisulfide reductase (HdrA2B2C2) in Methanosarcina acetivorans (2017), and Fd- and NADH-dependent ubiquinol reductase (FixABCX) in Azotobacter vinelandii (2017). The electron-bifurcating flavoprotein complexes known to date fall into four groups that have evolved independently, namely those containing EtfAB (CarED, LctCB, FixBA) with bound FAD, a NuoF homolog (HydB, HytB, or HylB) harboring FMN

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

Biochemical Changes in Terminal Root Galls Caused by an Ectoparasitic Nematode, Longidorus africanus: Amino Acids.

PubMed

Epstein, E; Cohn, E

1971-10-01

The amino acids of terminal root galls caused by Longidorus africanus on bur marigold (Bidens tripartita L.) and grapevine (Vitis vinifera L.) were studied. The galled roots of bur marigold contained 73% more cell-wall protein and 184% more free amino acids. The main changes among the free amino acids of the galled tissue were a large increase (1900%) in proline and a decrease in aspartic acid (56%) compared with the respective check tissue. Hydroxyproline decreased in the wall protein fraction from 5.6% in the healthy tissue to 3.6% in the infected tissue.Percent of hydroxyproline in total amino acids of the wall protein fraction of grapevine roots decreased from 0.7% in the healthy tissue to 0.3% in the galled tissue, and total proteins of this fraction decreased from 9.5 mg to 4.5 rag, respectively. Total protein in the protoplasmic fraction also decreased from 3.0 mg in healthy to 1.0 mg in infected roots. No change was noticed in total proteins in the free amino acids fraction but free proline decreased 40% in the infected roots.The relationship of these differences to the specific reactions of the hosts to nematode feeding is discussed.

78 FR 21627 - Endangered Species; Receipt of Applications for Permit

Federal Register 2010, 2011, 2012, 2013, 2014

2013-04-11

.... III. Permit Applications A. Endangered Species Applicant: Saint Louis Zoo, St. Louis, MO; PRT-94882A... wild ass (Equus africanus somalicus) that was held at San Diego Zoo until her death on May 3, 2010, for...

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. © The Author 2016. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Identification of aldolase and ferredoxin reductase within the dbt operon of Burkholderia fungorum DBT1.

PubMed

Piccoli, Stefano; Andreolli, Marco; Giorgetti, Alejandro; Zordan, Fabio; Lampis, Silvia; Vallini, Giovanni

2014-05-01

Burkholderia fungorum DBT1, first isolated from settling particulate matter of an oil refinery wastewater, is a bacterial strain which has been shown capable of utilizing several polycyclic aromatic hydrocarbons (PAHs) including dibenzothiophene (DBT). In particular, this microbe is able to efficiently degrade DBT through the Kodama pathway. Previous investigations have lead to the identification of six genes, on a total of eight, required for DBT degradation. In the present study, a combined experimental/computational approach was adopted to identify and in silico characterize the two missing genes, namely a ferredoxin reductase and a hydratase-aldolase. Thus, the finding of all enzymatic components of the Kodama pathway in B. fungorum DBT1 makes this bacterial strain amenable for possible exploitation in soil bioremediation protocols. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electronic, Magnetic, and Redox Properties of [MFe(3)S(4)] Clusters (M = Cd, Cu, Cr) in Pyrococcus furiosus Ferredoxin.

PubMed

Staples, Christopher R.; Dhawan, Ish K.; Finnegan, Michael G.; Dwinell, Derek A.; Zhou, Zhi Hao; Huang, Heshu; Verhagen, Marc F. J. M.; Adams, Michael W. W.; Johnson, Michael K.

1997-12-03

The ground- and excited-state properties of heterometallic [CuFe(3)S(4)](2+,+), [CdFe(3)S(4)](2+,+), and [CrFe(3)S(4)](2+,+) cubane clusters assembled in Pyrococcus furiosus ferredoxin have been investigated by the combination of EPR and variable-temperature/variable-field magnetic circular dichroism (MCD) studies. The results indicate Cd(2+) incorporation into [Fe(3)S(4)](0,-) cluster fragments to yield S = 2 [CdFe(3)S(4)](2+) and S = (5)/(2) [CdFe(3)S(4)](+) clusters and Cu(+) incorporation into [Fe(3)S(4)](+,0) cluster fragments to yield S = (1)/(2) [CuFe(3)S(4)](2+) and S = 2 [CuFe(3)S(4)](+) clusters. This is the first report of the preparation of cubane type [CrFe(3)S(4)](2+,+) clusters, and the combination of EPR and MCD results indicates S = 0 and S = (3)/(2) ground states for the oxidized and reduced forms, respectively. Midpoint potentials for the [CdFe(3)S(4)](2+,+), [CrFe(3)S(4)](2+,+), and [CuFe(3)S(4)](2+,+) couples, E(m) = -470 +/- 15, -440 +/- 10, and +190 +/- 10 mV (vs NHE), respectively, were determined by EPR-monitored redox titrations or direct electrochemistry at a glassy carbon electrode. The trends in redox potential, ground-state spin, and electron delocalization of [MFe(3)S(4)](2+,+) clusters in P. furiosus ferredoxin are discussed as a function of heterometal (M = Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, and Tl).

In Vitro Antifungal Susceptibility of Yeast and Mold Phases of Isolates of Dimorphic Fungal Pathogen Emergomyces africanus (Formerly Emmonsia sp.) 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

2017-06-01

Disseminated emmonsiosis is an important AIDS-related mycosis in South Africa that is caused by Emergomyces africanus , a newly described and renamed dimorphic fungal pathogen. In vitro antifungal susceptibility data can guide management. Identification of invasive clinical isolates was confirmed phenotypically and by sequencing of the internal transcribed spacer region. Yeast and mold phase MICs of fluconazole, voriconazole, itraconazole, posaconazole, caspofungin, anidulafungin, micafungin, and flucytosine were determined with custom-made frozen broth microdilution (BMD) panels in accordance with Clinical and Laboratory Standards Institute recommendations. MICs of amphotericin B, itraconazole, posaconazole, and voriconazole were determined by Etest. Fifty unique E. africanus isolates were tested. The yeast and mold phase geometric mean (GM) BMD and Etest MICs of itraconazole were 0.01 mg/liter. The voriconazole and posaconazole GM BMD MICs were 0.01 mg/liter for both phases, while the GM Etest MICs were 0.001 and 0.002 mg/liter, respectively. The fluconazole GM BMD MICs were 0.18 mg/liter for both phases. The GM Etest MICs of amphotericin B, for the yeast and mold phases were 0.03 and 0.01 mg/liter. 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 (odds ratio [OR], 8.6; 95% confidence interval [CI], 1.3 to 54.4; P = 0.02) or bone marrow (OR, 12.1; 95% CI, 1.2 to 120.2; P = 0.03) (versus skin biopsy) was associated with death. In vitro susceptibility data support the management of disseminated emmonsiosis with amphotericin B, followed by itraconazole, voriconazole, or posaconazole. Fluconazole was a relatively less potent agent. Copyright © 2017 American Society for Microbiology.

In Vitro Antifungal Susceptibility of Yeast and Mold Phases of Isolates of Dimorphic Fungal Pathogen Emergomyces africanus (Formerly Emmonsia sp.) from HIV-Infected South African Patients

PubMed Central

Britz, Erika; Zulu, Thokozile G.; Mpembe, Ruth S.; Naicker, Serisha D.; Schwartz, Ilan S.

2017-01-01

ABSTRACT Disseminated emmonsiosis is an important AIDS-related mycosis in South Africa that is caused by Emergomyces africanus, a newly described and renamed dimorphic fungal pathogen. In vitro antifungal susceptibility data can guide management. Identification of invasive clinical isolates was confirmed phenotypically and by sequencing of the internal transcribed spacer region. Yeast and mold phase MICs of fluconazole, voriconazole, itraconazole, posaconazole, caspofungin, anidulafungin, micafungin, and flucytosine were determined with custom-made frozen broth microdilution (BMD) panels in accordance with Clinical and Laboratory Standards Institute recommendations. MICs of amphotericin B, itraconazole, posaconazole, and voriconazole were determined by Etest. Fifty unique E. africanus isolates were tested. The yeast and mold phase geometric mean (GM) BMD and Etest MICs of itraconazole were 0.01 mg/liter. The voriconazole and posaconazole GM BMD MICs were 0.01 mg/liter for both phases, while the GM Etest MICs were 0.001 and 0.002 mg/liter, respectively. The fluconazole GM BMD MICs were 0.18 mg/liter for both phases. The GM Etest MICs of amphotericin B, for the yeast and mold phases were 0.03 and 0.01 mg/liter. 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 (odds ratio [OR], 8.6; 95% confidence interval [CI], 1.3 to 54.4; P = 0.02) or bone marrow (OR, 12.1; 95% CI, 1.2 to 120.2; P = 0.03) (versus skin biopsy) was associated with death. In vitro susceptibility data support the management of disseminated emmonsiosis with amphotericin B, followed by itraconazole, voriconazole, or posaconazole. Fluconazole was a relatively less potent agent. PMID:28356416

Site-directed mutagenesis of Azotobacter vinelandii ferredoxin I: [Fe-S] cluster-driven protein rearrangement.

PubMed Central

Martín, A E; Burgess, B K; Stout, C D; Cash, V L; Dean, D R; Jensen, G M; Stephens, P J

1990-01-01

Azotobacter vinelandii ferredoxin I is a small protein that contains one [4Fe-4S] cluster and one [3Fe-4S] cluster. Recently the x-ray crystal structure has been redetermined and the fdxA gene, which encodes the protein, has been cloned and sequenced. Here we report the site-directed mutation of Cys-20, which is a ligand of the [4Fe-4S] cluster in the native protein, to alanine and the characterization of the protein product by x-ray crystallographic and spectroscopic methods. The data show that the mutant protein again contains one [4Fe-4S] cluster and one [3Fe-4S] cluster. The new [4Fe-4S] cluster obtains its fourth ligand from Cys-24, a free cysteine in the native structure. The formation of this [4Fe-4S] cluster drives rearrangement of the protein structure. PMID:2153958

A quantitative and direct PCR assay for the subspecies-specific detection of Clavibacter michiganensis subsp. michiganensis based on a ferredoxin reductase gene.

PubMed

Cho, Min Seok; Lee, Jang Ha; Her, Nam Han; Kim, Changkug; Seol, Young-Joo; Hahn, Jang Ho; Baeg, Ji Hyoun; Kim, Hong Gi; Park, Dong Suk

2012-06-01

The Gram-positive bacterium Clavibacter michiganensis subsp. michiganensis is the causal agent of canker disease in tomato. Because it is very important to control newly introduced inoculum sources from commercial materials, the specific detection of this pathogen in seeds and seedlings is essential for effective disease control. In this study, a novel and efficient assay for the detection and quantitation of C. michiganensis subsp. michiganensis in symptomless tomato and red pepper seeds was developed. A pair of polymerase chain reaction (PCR) primers (Cmm141F/R) was designed to amplify a specific 141 bp fragment on the basis of a ferredoxin reductase gene of C. michiganensis subsp. michiganensis NCPPB 382. The specificity of the primer set was evaluated using purified DNA from 16 isolates of five C. michiganensis subspecies, one other Clavibacter species, and 17 other reference bacteria. The primer set amplified a single band of expected size from the genomic DNA obtained from the C. michiganensis subsp. michiganensis strains but not from the other C. michiganensis subspecies or from other Clavibacter species. The detection limit was a single cloned copy of the ferredoxin reductase gene of C. michiganensis subsp. michiganensis. In conclusion, this quantitative direct PCR assay can be applied as a practical diagnostic method for epidemiological research and the sanitary management of seeds and seedlings with a low level or latent infection of C. michiganensis subsp. michiganensis.

A Ferredoxin- and F 420 H 2 -Dependent, Electron-Bifurcating, Heterodisulfide Reductase with Homologs in the Domains Bacteria and Archaea

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yan, Zhen; Wang, Mingyu; Ferry, James G.

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; but, only one HdrABC has been characterized and that was from a narrow metabolic group of obligate CO 2-reducing methanogenic anaerobes (methanogens) from the domainArchaea. Here we report the biochemical characterization of an HdrABC homolog (HdrA2B2C2) from the acetate-utilizing methanogenMethanosarcina acetivoranswith unusual properties structurally and functionally distinct from the only other HdrABC characterized. Homologsmore » of the HdrA2B2C2 archetype are present in phylogenetically and metabolically diverse species from the domainsBacteriaandArchaea. The expression of the individual HdrA2, HdrB2, and HdrB2C2 enzymes inEscherichia coli, and reconstitution of an active HdrA2B2C2 complex, revealed an intersubunit electron transport pathway dependent on ferredoxin or coenzyme F 420(F 420H 2) as an electron donor. Remarkably, HdrA2B2C2 couples the previously unknown endergonic oxidation of F 420H 2and reduction of ferredoxin with the exergonic oxidation of F 420H 2and 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) byM. acetivoransand uncultured species from ANME environments. HdrA2B2C2, ubiquitous in acetotrophic methanogens, was shown to participate in electron transfer during acetotrophic growth ofM. acetivoransand proposed to be essential for growth in the environment when acetate is limiting.IMPORTANCEDiscovery of the archetype HdrA2B2C2 heterodisulfide reductase with categorically unique properties extends the understanding of this ancient family beyond CO 2-reducing

A Ferredoxin- and F 420 H 2 -Dependent, Electron-Bifurcating, Heterodisulfide Reductase with Homologs in the Domains Bacteria and Archaea

DOE PAGES

Yan, Zhen; Wang, Mingyu; Ferry, James G.; ...

2017-02-07

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; but, only one HdrABC has been characterized and that was from a narrow metabolic group of obligate CO 2-reducing methanogenic anaerobes (methanogens) from the domainArchaea. Here we report the biochemical characterization of an HdrABC homolog (HdrA2B2C2) from the acetate-utilizing methanogenMethanosarcina acetivoranswith unusual properties structurally and functionally distinct from the only other HdrABC characterized. Homologsmore » of the HdrA2B2C2 archetype are present in phylogenetically and metabolically diverse species from the domainsBacteriaandArchaea. The expression of the individual HdrA2, HdrB2, and HdrB2C2 enzymes inEscherichia coli, and reconstitution of an active HdrA2B2C2 complex, revealed an intersubunit electron transport pathway dependent on ferredoxin or coenzyme F 420(F 420H 2) as an electron donor. Remarkably, HdrA2B2C2 couples the previously unknown endergonic oxidation of F 420H 2and reduction of ferredoxin with the exergonic oxidation of F 420H 2and 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) byM. acetivoransand uncultured species from ANME environments. HdrA2B2C2, ubiquitous in acetotrophic methanogens, was shown to participate in electron transfer during acetotrophic growth ofM. acetivoransand proposed to be essential for growth in the environment when acetate is limiting.IMPORTANCEDiscovery of the archetype HdrA2B2C2 heterodisulfide reductase with categorically unique properties extends the understanding of this ancient family beyond CO 2-reducing

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

PubMed

Yan, Zhen; Wang, Mingyu; Ferry, James G

2017-02-07

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 CO 2 -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 F 420 (F 420 H 2 ) as an electron donor. Remarkably, HdrA2B2C2 couples the previously unknown endergonic oxidation of F 420 H 2 and reduction of ferredoxin with the exergonic oxidation of F 420 H 2 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. Discovery of the archetype HdrA2B2C2 heterodisulfide reductase with categorically unique properties extends the understanding of this ancient family beyond CO 2

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.

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.

Evidence for function of the ferredoxin/thioredoxin system in the reductive activation of target enzymes of isolated intact chloroplasts.

PubMed

Crawford, N A; Droux, M; Kosower, N S; Buchanan, B B

1989-05-15

Results obtained with isolated intact chloroplasts maintained aerobically under light and dark conditions confirm earlier findings with reconstituted enzyme assays and indicate that the ferredoxin/thioredoxin system functions as a light-mediated regulatory thiol chain. The results were obtained by application of a newly devised procedure in which a membrane-permeable thiol labeling reagent, monobromobimane (mBBr), reacts with sulfhydryl groups and renders the derivatized protein fluorescent. The mBBr-labeled protein in question is isolated individually from chloroplasts by immunoprecipitation and its thiol redox status is determined quantitatively by combining sodium dodecyl sulfate-polyacrylamide gel electrophoresis and fluorescence measurements. The findings indicate that each member of the ferredoxin/thioredoxin system containing a catalytically active thiol group is reduced in isolated intact chloroplasts after a 2-min illumination. The extents of reduction were FTR, 38%; thioredoxin m, 75% (11-kDa form) and 87% (13-kDa form); thioredoxin f, 95%. Reduction of each of these components was negligible both in the dark and when chloroplasts were transferred from light to dark conditions. The target enzyme, NADP-malate dehydrogenase, also underwent net reduction in illuminated intact chloroplasts. Fructose-1,6-bisphosphatase showed increased mBBr labeling under these conditions, but due to interfering gamma globulin proteins it was not possible to determine whether this was a result of net reduction as is known to take place in reconstituted assays. Related experiments demonstrated that mBBr, as well as N-ethylmaleimide, stabilized photoactivated NADP-malate dehydrogenase and fructose-1,6-bisphosphatase so that they remained active in the dark. By contrast, phosphoribulokinase, another thioredoxin-linked enzyme, was immediately deactivated following mBBr addition. These latter results provide new information on the relation between the regulatory and active sites of

Molecular interactions between photosystem I and ferredoxin: an integrated energy frustration and experimental model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cashman, Derek J.; Zhu, Tuo; Simmerman, Richard F.

2014-08-01

The stromal domain (PsaC, PsaD, and PsaE) of photosystem I (PSI) reduces transiently bound ferredoxin (Fd) or flavodoxin. Experimental structures exist for all of these protein partners individually, but no experimental structure of the PSI/Fd or PSI/flavodoxin complexes is presently available. Molecular models of Fd docked onto the stromal domain of the cyanobacterial PSI site are constructed here utilizing X-ray and NMR structures of PSI and Fd, respectively. Moreover, predictions of potential protein-protein interaction regions are based on experimental site-directed mutagenesis and cross-linking studies to guide rigid body docking calculations of Fd into PSI, complemented by energy landscape theory tomore » bring together regions of high energetic frustration on each of the interacting proteins. Results identify two regions of high localized frustration on the surface of Fd that contain negatively charged Asp and Glu residues. Our study predicts that these regions interact predominantly with regions of high localized frustration on the PsaC, PsaD, and PsaE chains of PSI, which include several residues predicted by previous experimental studies.« less

Biallelic mutations in the ferredoxin reductase gene cause novel mitochondriopathy with optic atrophy

PubMed Central

Peng, Yanyan; Shinde, Deepali N; Valencia, C Alexander; Mo, Jun-Song; Rosenfeld, Jill; Truitt Cho, Megan; Chamberlin, Adam; Li, Zhuo; Liu, Jie; Gui, Baoheng; Brockhage, Rachel; Basinger, Alice; Alvarez-Leon, Brenda; Heydemann, Peter; Magoulas, Pilar L; Lewis, Andrea M; Scaglia, Fernando; Gril, Solange; Chong, Shuk Ching; Bower, Matthew; Monaghan, Kristin G; Willaert, Rebecca; Plona, Maria-Renee; Dineen, Rich; Milan, Francisca; Hoganson, George; Helbig, Katherine L; Keller-Ramey, Jennifer; Harris, Belinda; Anderson, Laura C; Green, Torrian; Sukoff Rizzo, Stacey J; Kaylor, Julie; Chen, Jiani; Guan, Min-Xin; Sellars, Elizabeth; Sparagana, Steven P; Gibson, James B; Reinholdt, Laura G; Tang, Sha; Huang, Taosheng

2017-01-01

Abstract Iron–sulfur (Fe-S) clusters are ubiquitous cofactors essential to various cellular processes, including mitochondrial respiration, DNA repair, and iron homeostasis. A steadily increasing number of disorders are being associated with disrupted biogenesis of Fe–S clusters. Here, we conducted whole-exome sequencing of patients with optic atrophy and other neurological signs of mitochondriopathy and identified 17 individuals from 13 unrelated families with recessive mutations in FDXR, encoding the mitochondrial membrane-associated flavoprotein ferrodoxin reductase required for electron transport from NADPH to cytochrome P450. In vitro enzymatic assays in patient fibroblast cells showed deficient ferredoxin NADP reductase activity and mitochondrial dysfunction evidenced by low oxygen consumption rates (OCRs), complex activities, ATP production and increased reactive oxygen species (ROS). Such defects were rescued by overexpression of wild-type FDXR. Moreover, we found that mice carrying a spontaneous mutation allelic to the most common mutation found in patients displayed progressive gait abnormalities and vision loss, in addition to biochemical defects consistent with the major clinical features of the disease. Taken together, these data provide the first demonstration that germline, hypomorphic mutations in FDXR cause a novel mitochondriopathy and optic atrophy in humans. PMID:29040572

Photosynthetic and Heterotrophic Ferredoxin Isoproteins Are Colocalized in Fruit Plastids of Tomato1

PubMed Central

Aoki, Koh; Yamamoto, Miyuki; Wada, Keishiro

1998-01-01

Fruit tissues of tomato (Lycopersicon esculentum Mill.) contain both photosynthetic and heterotrophic ferredoxin (FdA and FdE, respectively) isoproteins, irrespective of their photosynthetic competence, but we did not previously determine whether these proteins were colocalized in the same plastids. In isolated fruit chloroplasts and chromoplasts, both FdA and FdE were detected by immunoblotting. Colocalization of FdA and FdE in the same plastids was demonstrated using double-staining immunofluorescence microscopy. We also found that FdA and FdE were colocalized in fruit chloroplasts and chloroamyloplasts irrespective of sink status of the plastid. Immunoelectron microscopy demonstrated that FdA and FdE were randomly distributed within the plastid stroma. To investigate the significance of the heterotrophic Fd in fruit plastids, Glucose 6-phosphate dehydrogenase (G6PDH) activity was measured in isolated fruit and leaf plastids. Fruit chloroplasts and chromoplasts showed much higher G6PDH activity than did leaf chloroplasts, suggesting that high G6PDH activity is linked with FdE to maintain nonphotosynthetic production of reducing power. This result suggested that, despite their morphological resemblance, fruit chloroplasts are functionally different from their leaf counterparts. PMID:9765529

Solution structure of an artificial Fe8S8 ferredoxin: the D13C variant of Bacillus schlegelii Fe7S8 ferredoxin.

PubMed

Aono, S; Bentrop, D; Bertini, I; Cosenza, G; Luchinat, C

1998-12-01

The solution structure of the D13C variant of the thermostable Fe7S8 ferredoxin from Bacillus schlegelii has been determined by 1H-NMR spectroscopy in its oxidized form. In a variable-temperature NMR study the D13C variant was as thermostable (up to 90 degrees C) as the wild-type protein (WT). Seventy-five out of 77 amino acid residues and 81% of all theoretically expected proton resonances in the D13C Fe8S8 protein have been assigned. Its structure was determined through torsion angle dynamics calculations with the program DYANA, using 935 meaningful NOEs (from a total of 1251), hydrogen bond constraints, and NMR-derived dihedral angle constraints for the cluster-ligating cysteines. Afterwards, restrained energy minimization and restrained molecular dynamics were applied to each conformer of the family. The final family of 20 structures has RMSD values from the mean structure of 0.055 nm for the backbone atoms and of 0.099 nm for all heavy atoms. The overall folding of the WT is maintained in the mutant, except for the immediate vicinity of the new cysteine, which becomes much more similar to native Fe8S8 proteins. The two residues at positions 11 and 12, which constitute an insertion with respect to all known Fe8S8 proteins, assume a conformation that does not prevent the preceding and following residues from folding like in native Fe8S8 proteins. Clear evidence for the existence of two conformations involving almost half of the amino acid residues was found. The two conformations are structurally indistinguishable. Temperature-dependent NMR experiments show that one of them is thermodynamically more stable than the other.

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

The Ferredoxin-Like Proteins HydN and YsaA Enhance Redox Dye-Linked Activity of the Formate Dehydrogenase H Component of the Formate Hydrogenlyase Complex.

PubMed

Pinske, Constanze

2018-01-01

Formate dehydrogenase H (FDH-H) and [NiFe]-hydrogenase 3 (Hyd-3) form the catalytic components of the hydrogen-producing formate hydrogenlyase (FHL) complex, which disproportionates formate to H 2 and CO 2 during mixed acid fermentation in enterobacteria. FHL comprises minimally seven proteins and little is understood about how this complex is assembled. Early studies identified a ferredoxin-like protein, HydN, as being involved in FDH-H assembly into the FHL complex. In order to understand how FDH-H and its small subunit HycB, which is also a ferredoxin-like protein, attach to the FHL complex, the possible roles of HydN and its paralogue, YsaA, in FHL complex stability and assembly were investigated. Deletion of the hycB gene reduced redox dye-mediated FDH-H activity to approximately 10%, abolished FHL-dependent H 2 -production, and reduced Hyd-3 activity. These data are consistent with HycB being an essential electron transfer component of the FHL complex. The FDH-H activity of the hydN and the ysaA deletion strains was reduced to 59 and 57% of the parental, while the double deletion reduced activity of FDH-H to 28% and the triple deletion with hycB to 1%. Remarkably, and in contrast to the hycB deletion, the absence of HydN and YsaA was without significant effect on FHL-dependent H 2 -production or total Hyd-3 activity; FDH-H protein levels were also unaltered. This is the first description of a phenotype for the E. coli ysaA deletion strain and identifies it as a novel factor required for optimal redox dye-linked FDH-H activity. A ysaA deletion strain could be complemented for FDH-H activity by hydN and ysaA , but the hydN deletion strain could not be complemented. Introduction of these plasmids did not affect H 2 production. Bacterial two-hybrid interactions showed that YsaA, HydN, and HycB interact with each other and with the FDH-H protein. Further novel anaerobic cross-interactions of 10 ferredoxin-like proteins in E. coli were also discovered and described

Biallelic mutations in the ferredoxin reductase gene cause novel mitochondriopathy with optic atrophy.

PubMed

Peng, Yanyan; Shinde, Deepali N; Valencia, C Alexander; Mo, Jun-Song; Rosenfeld, Jill; Truitt Cho, Megan; Chamberlin, Adam; Li, Zhuo; Liu, Jie; Gui, Baoheng; Brockhage, Rachel; Basinger, Alice; Alvarez-Leon, Brenda; Heydemann, Peter; Magoulas, Pilar L; Lewis, Andrea M; Scaglia, Fernando; Gril, Solange; Chong, Shuk Ching; Bower, Matthew; Monaghan, Kristin G; Willaert, Rebecca; Plona, Maria-Renee; Dineen, Rich; Milan, Francisca; Hoganson, George; Powis, Zoe; Helbig, Katherine L; Keller-Ramey, Jennifer; Harris, Belinda; Anderson, Laura C; Green, Torrian; Sukoff Rizzo, Stacey J; Kaylor, Julie; Chen, Jiani; Guan, Min-Xin; Sellars, Elizabeth; Sparagana, Steven P; Gibson, James B; Reinholdt, Laura G; Tang, Sha; Huang, Taosheng

2017-12-15

Iron-sulfur (Fe-S) clusters are ubiquitous cofactors essential to various cellular processes, including mitochondrial respiration, DNA repair, and iron homeostasis. A steadily increasing number of disorders are being associated with disrupted biogenesis of Fe-S clusters. Here, we conducted whole-exome sequencing of patients with optic atrophy and other neurological signs of mitochondriopathy and identified 17 individuals from 13 unrelated families with recessive mutations in FDXR, encoding the mitochondrial membrane-associated flavoprotein ferrodoxin reductase required for electron transport from NADPH to cytochrome P450. In vitro enzymatic assays in patient fibroblast cells showed deficient ferredoxin NADP reductase activity and mitochondrial dysfunction evidenced by low oxygen consumption rates (OCRs), complex activities, ATP production and increased reactive oxygen species (ROS). Such defects were rescued by overexpression of wild-type FDXR. Moreover, we found that mice carrying a spontaneous mutation allelic to the most common mutation found in patients displayed progressive gait abnormalities and vision loss, in addition to biochemical defects consistent with the major clinical features of the disease. Taken together, these data provide the first demonstration that germline, hypomorphic mutations in FDXR cause a novel mitochondriopathy and optic atrophy in humans. © The Author 2017. Published by Oxford University Press.

Sulfur K-Edge XAS Studies of the Effect of DNA Binding on the [Fe 4 S 4 ] Site in EndoIII and MutY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ha, Yang; Arnold, Anna R.; Nuñez, Nicole N.

S K-edge X-ray absorption spectroscopy (XAS) was used to study the [Fe 4S 4] clusters in the DNA repair glycosylases EndoIII and MutY to evaluate the effects of DNA binding and solvation on Fe–S bond covalencies (i.e., the amount of S 3p character mixed into the Fe 3d valence orbitals). Increased covalencies in both iron–thiolate and iron–sulfide bonds would stabilize the oxidized state of the [Fe 4S 4] clusters. Our results are compared to those on previously studied [Fe 4S 4] model complexes, ferredoxin (Fd), and to new data on high-potential iron–sulfur protein (HiPIP). A limited decrease in covalency ismore » observed upon removal of solvent water from EndoIII and MutY, opposite to the significant increase observed for Fd, where the [Fe 4S 4] cluster is solvent exposed. Importantly, in EndoIII and MutY, a large increase in covalency is observed upon DNA binding, which is due to the effect of its negative charge on the iron–sulfur bonds. Furthermore, in EndoIII, this change in covalency can be quantified and makes a significant contribution to the observed decrease in reduction potential found experimentally in DNA repair proteins, enabling their HiPIP-like redox behavior.« less

Sulfur K-Edge XAS Studies of the Effect of DNA Binding on the [Fe 4 S 4 ] Site in EndoIII and MutY

DOE PAGES

Ha, Yang; Arnold, Anna R.; Nuñez, Nicole N.; ...

2017-07-18

S K-edge X-ray absorption spectroscopy (XAS) was used to study the [Fe 4S 4] clusters in the DNA repair glycosylases EndoIII and MutY to evaluate the effects of DNA binding and solvation on Fe–S bond covalencies (i.e., the amount of S 3p character mixed into the Fe 3d valence orbitals). Increased covalencies in both iron–thiolate and iron–sulfide bonds would stabilize the oxidized state of the [Fe 4S 4] clusters. Our results are compared to those on previously studied [Fe 4S 4] model complexes, ferredoxin (Fd), and to new data on high-potential iron–sulfur protein (HiPIP). A limited decrease in covalency ismore » observed upon removal of solvent water from EndoIII and MutY, opposite to the significant increase observed for Fd, where the [Fe 4S 4] cluster is solvent exposed. Importantly, in EndoIII and MutY, a large increase in covalency is observed upon DNA binding, which is due to the effect of its negative charge on the iron–sulfur bonds. Furthermore, in EndoIII, this change in covalency can be quantified and makes a significant contribution to the observed decrease in reduction potential found experimentally in DNA repair proteins, enabling their HiPIP-like redox behavior.« less

Crystallization and preliminary X-ray diffraction studies of hyperthermophilic archaeal Rieske-type ferredoxin (ARF) from Sulfolobus solfataricus P1.

PubMed

Kounosu, Asako; Hasegawa, Kazuya; Iwasaki, Toshio; Kumasaka, Takashi

2010-07-01

The hyperthermophilic archaeal Rieske-type [2Fe-2S] ferredoxin (ARF) from Sulfolobus solfataricus P1 contains a low-potential Rieske-type [2Fe-2S] cluster that has served as a tractable model for ligand-substitution studies on this protein family. Recombinant ARF harbouring a pET30a vector-derived N-terminal extension region plus a hexahistidine tag has been heterologously overproduced in Escherichia coli, purified and crystallized by the hanging-drop vapour-diffusion method using 0.05 M sodium acetate, 0.05 M HEPES, 2 M ammonium sulfate pH 5.5. The crystals diffracted to 1.85 A resolution and belonged to the tetragonal space group P4(3)2(1)2, with unit-cell parameters a = 60.72, c = 83.31 A. The asymmetric unit contains one protein molecule.

Crystallization and preliminary X-ray diffraction studies of hyperthermophilic archaeal Rieske-type ferredoxin (ARF) from Sulfolobus solfataricus P1

PubMed Central

Kounosu, Asako; Hasegawa, Kazuya; Iwasaki, Toshio; Kumasaka, Takashi

2010-01-01

The hyperthermophilic archaeal Rieske-type [2Fe–2S] ferredoxin (ARF) from Sulfolobus solfataricus P1 contains a low-potential Rieske-type [2Fe–2S] cluster that has served as a tractable model for ligand-substitution studies on this protein family. Recombinant ARF harbouring a pET30a vector-derived N-­terminal extension region plus a hexahistidine tag has been heterologously overproduced in Escherichia coli, purified and crystallized by the hanging-drop vapour-diffusion method using 0.05 M sodium acetate, 0.05 M HEPES, 2 M ammonium sulfate pH 5.5. The crystals diffracted to 1.85 Å resolution and belonged to the tetragonal space group P43212, with unit-cell parameters a = 60.72, c = 83.31 Å. The asymmetric unit contains one protein molecule. PMID:20606288

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).

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. Copyright © 2013 Wiley Periodicals, Inc.

The systematic position of the enigmatic thyreophoran dinosaur Paranthodon africanus, and the use of basal exemplifiers in phylogenetic analysis.

PubMed

Raven, Thomas J; Maidment, Susannah C R

2018-01-01

The first African dinosaur to be discovered, Paranthodon africanus was found in 1845 in the Lower Cretaceous of South Africa. Taxonomically assigned to numerous groups since discovery, in 1981 it was described as a stegosaur, a group of armoured ornithischian dinosaurs characterised by bizarre plates and spines extending from the neck to the tail. This assignment has been subsequently accepted. The type material consists of a premaxilla, maxilla, a nasal, and a vertebra, and contains no synapomorphies of Stegosauria. Several features of the maxilla and dentition are reminiscent of Ankylosauria, the sister-taxon to Stegosauria, and the premaxilla appears superficially similar to that of some ornithopods. The vertebral material has never been described, and since the last description of the specimen, there have been numerous discoveries of thyreophoran material potentially pertinent to establishing the taxonomic assignment of the specimen. An investigation of the taxonomic and systematic position of Paranthodon is therefore warranted. This study provides a detailed re-description, including the first description of the vertebra. Numerous phylogenetic analyses demonstrate that the systematic position of Paranthodon is highly labile and subject to change depending on which exemplifier for the clade Stegosauria is used. The results indicate that the use of a basal exemplifier may not result in the correct phylogenetic position of a taxon being recovered if the taxon displays character states more derived than those of the basal exemplifier, and we recommend the use, minimally, of one basal and one derived exemplifier per clade. Paranthodon is most robustly recovered as a stegosaur in our analyses, meaning it is one of the youngest and southernmost stegosaurs.

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

USDA-ARS?s Scientific Manuscript database

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...

Dynamics of the active site architecture in plant-type ferredoxin-NADP(+) reductases catalytic complexes.

PubMed

Sánchez-Azqueta, Ana; Catalano-Dupuy, Daniela L; López-Rivero, Arleth; Tondo, María Laura; Orellano, Elena G; Ceccarelli, Eduardo A; Medina, Milagros

2014-10-01

Kinetic isotope effects in reactions involving hydride transfer and their temperature dependence are powerful tools to explore dynamics of enzyme catalytic sites. In plant-type ferredoxin-NADP(+) reductases the FAD cofactor exchanges a hydride with the NADP(H) coenzyme. Rates for these processes are considerably faster for the plastidic members (FNR) of the family than for those belonging to the bacterial class (FPR). Hydride transfer (HT) and deuteride transfer (DT) rates for the NADP(+) coenzyme reduction of four plant-type FNRs (two representatives of the plastidic type FNRs and the other two from the bacterial class), and their temperature dependences are here examined applying a full tunnelling model with coupled environmental fluctuations. Parameters for the two plastidic FNRs confirm a tunnelling reaction with active dynamics contributions, but isotope effects on Arrhenius factors indicate a larger contribution for donor-acceptor distance (DAD) dynamics in the Pisum sativum FNR reaction than in the Anabaena FNR reaction. On the other hand, parameters for bacterial FPRs are consistent with passive environmental reorganisation movements dominating the HT coordinate and no contribution of DAD sampling or gating fluctuations. This indicates that active sites of FPRs are more organised and rigid than those of FNRs. These differences must be due to adaptation of the active sites and catalytic mechanisms to fulfil their particular metabolic roles, establishing a compromise between protein flexibility and functional optimisation. Analysis of site-directed mutants in plastidic enzymes additionally indicates the requirement of a minimal optimal architecture in the catalytic complex to provide a favourable gating contribution. Copyright © 2014 Elsevier B.V. All rights reserved.

[4Fe-4S]-cluster-depleted Azotobacter vinelandii ferredoxin I: a new 3Fe iron-sulfur protein.

PubMed Central

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

1985-01-01

Fe(CN)6(-3) 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)6(-3)/(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 approximately equal to 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. PMID:2994040

A novel plant ferredoxin-like protein and the regulator Hor are quorum-sensing targets in the plant pathogen Erwinia carotovora.

PubMed

Sjöblom, Solveig; Harjunpää, Heidi; Brader, Günter; Palva, E Tapio

2008-07-01

Quorum sensing (QS), a population-density-sensing mechanism, controls the production of the main virulence determinants, the plant cell-wall-degrading enzymes (PCWDEs) of the soft-rot phytopathogen Erwinia carotovora subsp. carotovora. In this study, we used random transposon mutagenesis with a gusA reporter construct to identify two new QS-controlled genes encoding the regulator Hor and a plant ferredoxin-like protein, FerE. The QS control of the identified genes was executed by the QS regulators ExpR1 and ExpR2 and mediated by the global repressor RsmA. Hor was shown to contribute to bacterial virulence at least partly through its control of PCWDE production. Our results showed that FerE contributes to oxidative stress tolerance and in planta fitness of the bacteria and suggest that QS could be central to control of oxidative stress tolerance. The presence of the FerE protein appears to be rather unique in heterotrophic bacteria and suggests an acquisition of the corresponding gene from plant host by horizontal gene transfer.

Binding of Pseudomonas aeruginosa Apo-Bacterioferritin Associated Ferredoxin to Bacterioferritin B Promotes Heme Mediation of Electron Delivery and Mobilization of Core Mineral Iron†

PubMed Central

Weeratunga, Saroja K.; Gee, Casey E.; Lovell, Scott; Zeng, Yuhong; Woodin, Carrie L.; Rivera, Mario

2009-01-01

The bfrB gene from Pseudomonas aeruginosa was cloned and expressed in E. coli. The resultant protein (BfrB), which assembles into a 445.3 kDa complex0020from 24 identical subunits, binds 12 molecules of heme axially coordinated by two Met residues. BfrB, isolated with 5–10 iron atoms per protein molecule, was reconstituted with ferrous ions to prepare samples with a core mineral containing 600 ± 40 ferric ions per BfrB molecule and approximately one phosphate molecule per iron atom. In the presence of sodium dithionite or in the presence of P. aeruginosa ferredoxin NADP reductase (FPR) and NADPH the heme in BfrB remains oxidized and the core iron mineral is mobilized sluggishly. In stark contrast, addition of NADPH to a solution containing BfrB, FPR and the apo-form of P. aeruginosa bacterioferritin associated ferredoxin (apo-Bfd) results in rapid reduction of the heme in BfrB and in the efficient mobilization of the core iron mineral. Results from additional experimentation indicate that Bfd must bind to BfrB to promote heme mediation of electrons from the surface to the core to support the efficient mobilization of ferrous ions from BfrB. In this context, the thus far mysterious role of heme in bacterioferritins has been brought to the front by reconstituting BfrB with its physiological partner, apo-Bfd. These findings are discussed in the context of a model for the utilization of stored iron in which the significant upregulation of the bfd gene under low-iron conditions [Ochsner, U.A., Wilderman, P.J., Vasil, A.I., and Vasil, M.L. (2002) Mol. Microbiol. 45, 1277–1287] ensures sufficient concentrations of apo-Bfd to bind BfrB and unlock the iron stored in its core. Although these findings are in contrast to previous speculations suggesting redox mediation of electron transfer by holo-Bfd, the ability of apo-Bfd to promote iron mobilization is an economical strategy used by the cell because it obviates the need to further deplete cellular iron levels to

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

Cellular Assays for Ferredoxins: A Strategy for Understanding Electron Flow through Protein Carriers That Link Metabolic Pathways.

PubMed

Atkinson, Joshua T; Campbell, Ian; Bennett, George N; Silberg, Jonathan J

2016-12-27

The ferredoxin (Fd) protein family is a structurally diverse group of iron-sulfur proteins that function as electron carriers, linking biochemical pathways important for energy transduction, nutrient assimilation, and primary metabolism. While considerable biochemical information about individual Fd protein electron carriers and their reactions has been acquired, we cannot yet anticipate the proportion of electrons shuttled between different Fd-partner proteins within cells using biochemical parameters that govern electron flow, such as holo-Fd concentration, midpoint potential (driving force), molecular interactions (affinity and kinetics), conformational changes (allostery), and off-pathway electron leakage (chemical oxidation). Herein, we describe functional and structural gaps in our Fd knowledge within the context of a sequence similarity network and phylogenetic tree, and we propose a strategy for improving our understanding of Fd sequence-function relationships. We suggest comparing the functions of divergent Fds within cells whose growth, or other measurable output, requires electron transfer between defined electron donor and acceptor proteins. By comparing Fd-mediated electron transfer with biochemical parameters that govern electron flow, we posit that models that anticipate energy flow across Fd interactomes can be built. This approach is expected to transform our ability to anticipate Fd control over electron flow in cellular settings, an obstacle to the construction of synthetic electron transfer pathways and rational optimization of existing energy-conserving pathways.

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.

Classification of heparinolytic bacteria into a new genus, Pedobacter, comprising four species: Pedobacter heparinus comb. nov., Pedobacter piscium comb. nov., Pedobacter africanus sp. nov. and Pedobacter saltans sp. nov. proposal of the family Sphingobacteriaceae fam. nov.

PubMed

Steyn, P L; Segers, P; Vancanneyt, M; Sandra, P; Kersters, K; Joubert, J J

1998-01-01

Sixteen heparinase-producing isolates, related to Sphingobacterium heparinum, were grouped into three major clusters by SDS-PAGE and DNA-rRNA hybridizations. Based on a polyphasic approach, it was shown that isolates of two of these clusters and S. heparinum species belong to a new genus for which the name Pedobacter is proposed. The genus consists of Pedobacter heparinus comb. nov. (formerly Sphingobacterium heparinum), which is the type species, Pedobacter piscium comb. nov. (formerly Sphingobacterium piscium), Pedobacter africanus sp. nov. and Pedobacter saltans sp. nov. and four as-yet-unnamed DNA hybridization groups. All the previously named taxa can be discriminated by phenotypic features, but have strong overall similarities with representatives of the genus Sphingobacterium and the misclassified species [Flexibacter] canadensis. All these organisms constitute a separate rRNA branch in rRNA superfamily V for which the family Sphingobacteriaceae fam. nov. is proposed.

Evaluation of the participation of ferredoxin in oxygen reduction in the photosynthetic electron transport chain of isolated pea thylakoids.

PubMed

Kozuleva, Marina A; Ivanov, Boris N

2010-07-01

The contribution to reduction of oxygen by ferredoxin (Fd) to the overall reduction of oxygen in isolated pea thylakoids was studied in the presence of Fd versus Fd + NADP(+). The overall rate of electron transport was measured using a determination of Photosystem II quantum yield from chlorophyll fluorescence parameters, and the rate of oxidation of Fd was measured from the light-induced redox changes of Fd. At low light intensity, increasing Fd concentration from 5 to 30 microM in the absence of NADP(+) increased the proportion of oxygen reduction by Fd from 25-35 to 40-60% in different experiments. This proportion decreased with increasing light intensity. When NADP(+) was added in the presence of 15 microM Fd, which was optimal for the NADP(+) reduction rate, the participation of Fd in the reduction of oxygen was low, no more than 10%, and it also decreased with increasing light intensity. At high light intensity, the overall oxygen reduction rates in the presence of Fd + NADP(+) and in the presence of Fd alone were comparable. The significance of reduction of dioxygen either by water-soluble Fd or by the membrane-bound carriers of the photosynthetic electron transport chain for redox signaling under different light intensities is discussed.

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

PubMed

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

2016-07-01

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. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Role of a Ferredoxin Gene Cotranscribed with the nifHDK Operon in N2 Fixation and Nitrogenase “Switch-Off” of Azoarcus sp. Strain BH72

PubMed Central

Egener, Tanja; Martin, Dietmar E.; Sarkar, Abhijit; Reinhold-Hurek, Barbara

2001-01-01

The endophytic diazotroph Azoarcus sp. strain BH72 is capable of infecting rice roots and of expressing the nitrogenase (nif) genes there. In order to study the genetic background for nitrogen fixation in strain BH72, the structural genes of nitrogenase (nifHDK) were cloned and sequenced. The sequence analysis revealed an unusual gene organization: downstream of nifHDK, a ferredoxin gene (fdxN; 59% amino acid sequence identity to R. capsulatus FdxN) and open reading frames showing 52 and 36% amino acid sequence identity to nifY of Pseudomonas stutzeri A15 and ORF1 of Azotobacter vinelandii were located. Northern blot analysis, reverse transcriptase PCR and primer extension analysis revealed that these six genes are located on one transcript transcribed from a ς54-type promoter. Shorter transcripts sequentially missing genes of the 3′ part of the full-length mRNA were more abundantly detected. Mutational analyses suggested that FdxN is an important but not the essential electron donor for dinitrogenase reductase. An in-frame deletion of fdxN resulted in reduced growth rates (59% ± 9%) and nitrogenase activities (81%) in nitrogen-fixing pure cultures in comparison to the wild type. Nitrogenase activity was fully complemented in an fdxN mutant which carried a nifH promoter-driven fdxN gene in trans. Also, in coculture with the ascomycete Acremonium alternatum, where strain BH72 develops intracytoplasmic membrane stacks, the nitrogenase activity in the fdxN deletion mutant was decreased to 56% of the wild-type level. Surprisingly, the fdxN deletion also had an effect on the rapid “switch-off” of nitrogenase activity in response to ammonium. Wild-type strain BH72 and the deletion mutant complemented with fdxN in trans showed a rapid reversible inactivation of acetylene reduction, while the deletion mutant did not cease to reduce acetylene. In concordance with the hypothesis that changes in the redox state of NifH or electron flux towards nitrogenase may be

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wei, Yifeng; Li, Bin; Prakash, Divya

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 RNRsmore » reflects the diversity of electron carriers used in anaerobic metabolism« less

Rice Ferredoxin-Dependent Glutamate Synthase Regulates Nitrogen-Carbon Metabolomes and Is Genetically Differentiated between japonica and indica Subspecies.

PubMed

Yang, Xiaolu; Nian, Jinqiang; Xie, Qingjun; Feng, Jian; Zhang, Fengxia; Jing, Hongwei; Zhang, Jian; Dong, Guojun; Liang, Yan; Peng, Juli; Wang, Guodong; Qian, Qian; Zuo, Jianru

2016-11-07

Plants assimilate inorganic nitrogen absorbed from soil into organic forms as Gln and Glu through the glutamine synthetase/glutamine:2-oxoglutarate amidotransferase (GS/GOGAT) cycle. Whereas GS catalyzes the formation of Gln from Glu and ammonia, GOGAT catalyzes the transfer of an amide group from Gln to 2-oxoglutarate to produce two molecules of Glu. However, the regulatory role of the GS/GOGAT cycle in the carbon-nitrogen balance is not well understood. Here, we report the functional characterization of rice ABNORMAL CYTOKININ RESPONSE 1 (ABC1) gene that encodes a ferredoxin-dependent (Fd)-GOGAT. The weak mutant allele abc1-1 mutant shows a typical nitrogen-deficient syndrome, whereas the T-DNA insertional mutant abc1-2 is seedling lethal. Metabolomics analysis revealed the accumulation of an excessive amount of amino acids with high N/C ratio (Gln and Asn) and several intermediates in the tricarboxylic acid cycle in abc1-1, suggesting that ABC1 plays a critical role in nitrogen assimilation and carbon-nitrogen balance. Five non-synonymous single-nucleotide polymorphisms were identified in the ABC1 coding region and characterized as three distinct haplotypes, which have been highly and specifically differentiated between japonica and indica subspecies. Collectively, these results suggest that ABC1/OsFd-GOGAT is essential for plant growth and development by modulating nitrogen assimilation and the carbon-nitrogen balance. Copyright © 2016 The Author. Published by Elsevier Inc. All rights reserved.

Expression, purification, crystallization and preliminary X-ray crystallographic analysis of a novel plant-type ferredoxin/thioredoxin reductase-like protein from Methanosarcina acetivorans

PubMed Central

Kumar, Adepu K.; Yennawar, Neela H.; Yennawar, Hemant P.; Ferry, James G.

2011-01-01

The genome of Methanosarcina acetivorans contains a gene (ma1659) that is predicted to encode an uncharacterized chimeric protein containing a plant-type ferredoxin/thioredoxin reductase-like catalytic domain in the N-terminal region and a bacterial-like rubredoxin domain in the C-terminal region. To understand the structural and functional properties of the protein, the ma1659 gene was cloned and overexpressed in Escherichia coli. Crystals of the MA1659 protein were grown by the sitting-drop method using 2 M ammonium sulfate, 0.1 M HEPES buffer pH 7.5 and 0.1 M urea. Diffraction data were collected to 2.8 Å resolution using the remote data-collection feature of the Advanced Light Source, Lawrence Berkeley National Laboratory. The crystal belonged to the primitive cubic space group P23 or P213, with unit-cell parameters a = b = c = 92.72 Å. Assuming the presence of one molecule in the asymmetric unit gave a Matthews coefficient (V M) of 3.55 Å3 Da−1, corresponding to a solvent content of 65%. PMID:21795791

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

Magnetic Nature of the CrIII-LnIII Interactions in [CrIII2LnIII3] Clusters with Slow Magnetic Relaxation.

PubMed

Zhao, Xiao-Qing; Xiang, Shuo; Wang, Jin; Bao, Dong-Xu; Li, Yun-Chun

2018-02-01

Two 3 d -4 f hetero-metal pentanuclear complexes with the formula {[Cr III 2 Ln III 3 L 10 (OH) 6 (H 2 O) 2 ]Et 3 NH} [Ln=Tb ( 1 ), Dy ( 2 ); HL=pivalic acid, Et 3 N=triethylamine] have been produced. The metal core of each cluster is made up of a trigonal bipyramid with three Ln III ions (plane) and two Cr III ions (above and below) held together by six μ 3 -OH bridges. Also reported with this series is the diamagnetic Cr III -Y III analogue ( 3 ). Fortunately, we successfully prepared Al III -Ln III analogues with the formula {[Al III 2 Ln III 3 L 10 (OH) 6 (H 2 O) 2 ]Et 3 NH⋅H 2 O} [Ln=Tb ( 4 ), Dy ( 5 )], containing diamagnetic Al III ions, which can be used to evaluate the Cr III -Ln III magnetic nature through a diamagnetic substitution method. Subsequently, static (dc) magnetic susceptibility studies reveal dominant ferromagnetic interactions between Cr III and Ln III ions. Dynamic (ac) magnetic susceptibility studies show frequency-dependent out-of-phase ( χ '') signals for [Cr III 2 Tb III 3 ] ( 1 ), [Cr III 2 Dy III 3 ] ( 2 ), and [Al III 2 Dy III 3 ] ( 5 ), which are derived from the single-ion behavior of Ln III ions and/or the Cr III -Ln III ferromagnetic interactions.

Rapid-mix and chemical quench studies of ferredoxin-reduced stearoyl-acyl carrier protein desaturase.

PubMed

Lyle, Karen S; Haas, Jeffrey A; Fox, Brian G

2003-05-20

Stearoyl-ACP Delta9 desaturase (Delta9D) catalyzes the NADPH- and O(2)-dependent insertion of a cis double bond between the C9 and C10 positions of stearoyl-ACP (18:0-ACP) to produce oleoyl-ACP (18:1-ACP). This work revealed the ability of reduced [2Fe-2S] ferredoxin (Fd) to act as a catalytically competent electron donor during the rapid conversion of 18:0-ACP into 18:1-ACP. Experiments on the order of addition for substrate and reduced Fd showed high conversion of 18:0-ACP to 18:1-ACP (approximately 95% per Delta9D active site in a single turnover) when 18:0-ACP was added prior to reduced Fd. Reactions of the prereduced enzyme-substrate complex with O(2) and the oxidized enzyme-substrate complex with reduced Fd were studied by rapid-mix and chemical quench methods. For reaction of the prereduced enzyme-substrate complex, an exponential burst phase (k(burst) = 95 s(-1)) of product formation accounted for approximately 90% of the turnover expected for one subunit in the dimeric protein. This rapid phase was followed by a slower phase (k(linear) = 4.0 s(-1)) of product formation corresponding to the turnover expected from the second subunit. For reaction of the oxidized enzyme-substrate complex with excess reduced Fd, a slower, linear rate (k(obsd) = 3.4 s(-1)) of product formation was observed over approximately 1.5 turnovers per Delta9D active site potentially corresponding to a third phase of reaction. An analysis of the deuterium isotope effect on the two rapid-mix reaction sequences revealed only a modest effect on k(burst) ((D)k(burst) approximately 1.5) and k(linear) (D)k(linear) approximately 1.4), indicating C-H bond cleavage does not contribute significantly to the rate-limiting steps of pre-steady-state catalysis. These results were used to assemble and evaluate a minimal kinetic model for Delta9D catalysis.

A physiological perspective on the origin and evolution of photosynthesis

PubMed Central

Martin, William F; Bryant, Donald A; Beatty, J Thomas

2017-01-01

Abstract The origin and early evolution of photosynthesis are reviewed from an ecophysiological perspective. Earth's first ecosystems were chemotrophic, fueled by geological H2 at hydrothermal vents and, required flavin-based electron bifurcation to reduce ferredoxin for CO2 fixation. Chlorophyll-based phototrophy (chlorophototrophy) allowed autotrophs to generate reduced ferredoxin without electron bifurcation, providing them access to reductants other than H2. Because high-intensity, short-wavelength electromagnetic radiation at Earth's surface would have been damaging for the first chlorophyll (Chl)-containing cells, photosynthesis probably arose at hydrothermal vents under low-intensity, long-wavelength geothermal light. The first photochemically active pigments were possibly Zn-tetrapyrroles. We suggest that (i) after the evolution of red-absorbing Chl-like pigments, the first light-driven electron transport chains reduced ferredoxin via a type-1 reaction center (RC) progenitor with electrons from H2S; (ii) photothioautotrophy, first with one RC and then with two, was the bridge between H2-dependent chemolithoautotrophy and water-splitting photosynthesis; (iii) photothiotrophy sustained primary production in the photic zone of Archean oceans; (iv) photosynthesis arose in an anoxygenic cyanobacterial progenitor; (v) Chl a is the ancestral Chl; and (vi), anoxygenic chlorophototrophic lineages characterized so far acquired, by horizontal gene transfer, RCs and Chl biosynthesis with or without autotrophy, from the architects of chlorophototrophy—the cyanobacterial lineage. PMID:29177446

Observations on the Feeding and Symptomatology of Xiphinema and Longidorus on Selected Host Roots

PubMed Central

Cohn, E.

1970-01-01

In vitro feeding of Xiphinema brevicolle, X. index and Longidorus africanus on roots of host seedlings is described. Both Xiphinema spp. fed mainly along roots rather than at tips and up to several days at a single site. Feeding of L. africanus was confined to root tips and lasted up to 15 min. No visible short term reaction of roots parasitized by the Xiphinema spp. could be discerned, but both swelling and cessation of growth of root tips were observed within 20 hr after feeding by L. africanus. Long-term (12-month) symptoms on roots of several host plants caused by cultured populations of X. brevicolle, X. index, X. italiae, L. africanus and L. brevicaudatus are described. All the Xiphinema spp. caused a thinning and distinct darkening of root systems and, at some sites, a breakdown of the cortex. Both species of Longidorus caused stubby and swollen root tips. Root symptom severity was in proportion to nematode population levels. PMID:19322291

Insights into electron flux through manipulation of fermentation conditions and assessment of protein expression profiles in Clostridium thermocellum.

PubMed

Rydzak, Thomas; Grigoryan, Marina; Cunningham, Zack J; Krokhin, Oleg V; Ezzati, Peyman; Cicek, Nazim; Levin, David B; Wilkins, John A; Sparling, Richard

2014-01-01

While annotation of the genome sequence of Clostridium thermocellum has allowed predictions of pathways catabolizing cellobiose to end products, ambiguities have persisted with respect to the role of various proteins involved in electron transfer reactions. A combination of growth studies modulating carbon and electron flow and multiple reaction monitoring (MRM) mass spectrometry measurements of proteins involved in central metabolism and electron transfer was used to determine the key enzymes involved in channeling electrons toward fermentation end products. Specifically, peptides belonging to subunits of ferredoxin-dependent hydrogenase and NADH:ferredoxin oxidoreductase (NFOR) were low or below MRM detection limits when compared to most central metabolic proteins measured. The significant increase in H2 versus ethanol synthesis in response to either co-metabolism of pyruvate and cellobiose or hypophosphite mediated pyruvate:formate lyase inhibition, in conjunction with low levels of ferredoxin-dependent hydrogenase and NFOR, suggest that highly expressed putative bifurcating hydrogenases play a substantial role in reoxidizing both reduced ferredoxin and NADH simultaneously. However, product balances also suggest that some of the additional reduced ferredoxin generated through increased flux through pyruvate:ferredoxin oxidoreductase must be ultimately converted into NAD(P)H either directly via NADH-dependent reduced ferredoxin:NADP(+) oxidoreductase (NfnAB) or indirectly via NADPH-dependent hydrogenase. While inhibition of hydrogenases with carbon monoxide decreased H2 production 6-fold and redirected flux from pyruvate:ferredoxin oxidoreductase to pyruvate:formate lyase, the decrease in CO2 was only 20 % of that of the decrease in H2, further suggesting that an alternative redox system coupling ferredoxin and NAD(P)H is active in C. thermocellum in lieu of poorly expressed ferredoxin-dependent hydrogenase and NFOR.

Sodium ion pumps and hydrogen production in glutamate fermenting anaerobic bacteria.

PubMed

Boiangiu, Clara D; Jayamani, Elamparithi; Brügel, Daniela; Herrmann, Gloria; Kim, Jihoe; Forzi, Lucia; Hedderich, Reiner; Vgenopoulou, Irini; Pierik, Antonio J; Steuber, Julia; Buckel, Wolfgang

2005-01-01

Anaerobic bacteria ferment glutamate via two different pathways to ammonia, carbon dioxide, acetate, butyrate and molecular hydrogen. The coenzyme B12-dependent pathway in Clostridium tetanomorphum via 3-methylaspartate involves pyruvate:ferredoxin oxidoreductase and a novel enzyme, a membrane-bound NADH:ferredoxin oxidoreductase. The flavin- and iron-sulfur-containing enzyme probably uses the energy difference between reduced ferredoxin and NADH to generate an electrochemical Na+ gradient, which drives transport processes. The other pathway via 2-hydroxyglutarate in Acidaminococcus fermentans and Fusobacterium nucleatum involves glutaconyl-CoA decarboxylase, which uses the free energy of decarboxylation to generate also an electrochemical Na+ gradient. In the latter two organisms, similar membrane-bound NADH:ferredoxin oxidoreductases have been characterized. We propose that in the hydroxyglutarate pathway these oxidoreductases work in the reverse direction, whereby the reduction of ferredoxin by NADH is driven by the Na+ gradient. The reduced ferredoxin is required for hydrogen production and the activation of radical enzymes. Further examples show that reduced ferredoxin is an agent, whose reducing energy is about 1 ATP 'richer' than that of NADH. Copyright 2005 S. Karger AG, Basel.

Structural Analysis of Proteins in Extreme Saline Environments

DTIC Science & Technology

1989-03-16

ferredoxinz with the same 2Fe-2S prosthetic group trom the blue-green algae Spirulina platensis (SplFd) (K. Fukuyama et al., 1980; Tsukihara et al...8 b) Molecular Conformation of 2Fe-2S Ferredoxin....................................9 c) Similarity to 2Fe-2S Ferredoxin from Spiruifina platensis ...ferredoxin from Peptococcus aerogenes (Adman, Sicker & Jensen, 1972; Carter et al., 1974). c) Similarity to 2Fe-2S Ferredoxin from Svindina platensis The

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. Copyright © 2015 Elsevier B.V. All rights reserved.

Amphiphilic complexes of Ho(iii), Dy(iii), Tb(iii) and Eu(iii) for optical and high field magnetic resonance imaging.

PubMed

Harris, Michael; Henoumont, Céline; Peeters, Wannes; Toyouchi, Shuichi; Vander Elst, Luce; Parac-Vogt, Tatjana N

2018-05-29

Lanthanides, holmium(iii), dysprosium(iii), and terbium(iii), were coordinated to an amphiphilic DOTA bis-coumarin derivative and then further assembled with an amphiphilic europium(iii) DTPA bis-coumarin derivative into mono-disperse micelles. The self-assembled micelles were characterized and assessed for their potential as bimodal contrast agents for high field magnetic resonance and optical imaging applications. All micelles showed a high transverse relaxation (r2) of 46, 34, and 30 s-1 mM-1 at 500 MHz and 37 °C for Dy(iii), Ho(iii) and Tb(iii), respectively, which is a result of the high magnetic moment of these lanthanides and the long rotational correlation time of the micelles. The quantum yield in aqueous solution ranged from 1.8% for Tb/Eu to 1.4% for Dy/Eu and 1.0% for the Ho/Eu micelles. Multi-photon excited emission spectroscopy has shown that due to the two-photon absorption of the coumarin chromophore the characteristic Eu(iii) emission could be observed upon excitation at 800 nm, demonstrating the usefulness of the system for in vivo fluorescence imaging applications. To the best of our knowledge, this is the first example reporting the potential of a holmium(iii) chelate as a negative MRI contrast agent.

Uranium (III)-Plutonium (III) co-precipitation in molten chloride

NASA Astrophysics Data System (ADS)

Vigier, Jean-François; Laplace, Annabelle; Renard, Catherine; Miguirditchian, Manuel; Abraham, Francis

2018-02-01

Co-management of the actinides in an integrated closed fuel cycle by a pyrochemical process is studied at the laboratory scale in France in the CEA-ATALANTE facility. In this context the co-precipitation of U(III) and Pu(III) by wet argon sparging in LiCl-CaCl2 (30-70 mol%) molten salt at 705 °C is studied. Pu(III) is prepared in situ in the molten salt by carbochlorination of PuO2 and U(III) is then introduced as UCl3 after chlorine purge by argon to avoid any oxidation of uranium up to U(VI) by Cl2. The oxide conversion yield through wet argon sparging is quantitative. However, the preferential oxidation of U(III) in comparison to Pu(III) is responsible for a successive conversion of the two actinides, giving a mixture of UO2 and PuO2 oxides. Surprisingly, the conversion of sole Pu(III) in the same conditions leads to a mixture of PuO2 and PuOCl, characteristic of a partial oxidation of Pu(III) to Pu(IV). This is in contrast with coconversion of U(III)-Pu(III) mixtures but in agreement with the conversion of Ce(III).

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.

Deconvolution of ferredoxin, plastocyanin, and P700 transmittance changes in intact leaves with a new type of kinetic LED array spectrophotometer.

PubMed

Klughammer, Christof; Schreiber, Ulrich

2016-05-01

A newly developed compact measuring system for assessment of transmittance changes in the near-infrared spectral region is described; it allows deconvolution of redox changes due to ferredoxin (Fd), P700, and plastocyanin (PC) in intact leaves. In addition, it can also simultaneously measure chlorophyll fluorescence. The major opto-electronic components as well as the principles of data acquisition and signal deconvolution are outlined. Four original pulse-modulated dual-wavelength difference signals are measured (785-840 nm, 810-870 nm, 870-970 nm, and 795-970 nm). Deconvolution is based on specific spectral information presented graphically in the form of 'Differential Model Plots' (DMP) of Fd, P700, and PC that are derived empirically from selective changes of these three components under appropriately chosen physiological conditions. Whereas information on maximal changes of Fd is obtained upon illumination after dark-acclimation, maximal changes of P700 and PC can be readily induced by saturating light pulses in the presence of far-red light. Using the information of DMP and maximal changes, the new measuring system enables on-line deconvolution of Fd, P700, and PC. The performance of the new device is demonstrated by some examples of practical applications, including fast measurements of flash relaxation kinetics and of the Fd, P700, and PC changes paralleling the polyphasic fluorescence rise upon application of a 300-ms pulse of saturating light.

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.

Magnetic Nature of the CrIII–LnIII Interactions in [CrIII 2LnIII 3] Clusters with Slow Magnetic Relaxation

PubMed Central

Xiang, Shuo; Wang, Jin; Bao, Dong‐Xu; Li, Yun‐Chun

2018-01-01

Abstract Two 3d‐4f hetero‐metal pentanuclear complexes with the formula {[CrIII 2LnIII 3L10(OH)6(H2O)2]Et3NH} [Ln=Tb (1), Dy (2); HL=pivalic acid, Et3N=triethylamine] have been produced. The metal core of each cluster is made up of a trigonal bipyramid with three LnIII ions (plane) and two CrIII ions (above and below) held together by six μ 3‐OH bridges. Also reported with this series is the diamagnetic CrIII–YIII analogue (3). Fortunately, we successfully prepared AlIII–LnIII analogues with the formula {[AlIII 2LnIII 3L10(OH)6(H2O)2]Et3NH⋅H2O} [Ln=Tb (4), Dy (5)], containing diamagnetic AlIII ions, which can be used to evaluate the CrIII–LnIII magnetic nature through a diamagnetic substitution method. Subsequently, static (dc) magnetic susceptibility studies reveal dominant ferromagnetic interactions between CrIII and LnIII ions. Dynamic (ac) magnetic susceptibility studies show frequency‐dependent out‐of‐phase (χ′′) signals for [CrIII 2TbIII 3] (1), [CrIII 2DyIII 3] (2), and [AlIII 2DyIII 3] (5), which are derived from the single‐ion behavior of LnIII ions and/or the CrIII–LnIII ferromagnetic interactions. PMID:29435404

Aqueous light driven hydrogen production by a Ru–ferredoxin–Co biohybrid

DOE PAGES

Soltau, Sarah R.; Niklas, Jens; Dahlberg, Peter D.; ...

2015-06-08

In this paper, we report the creation of a novel solar fuel biohybrid for light-driven H 2 production utilizing the native electron transfer protein ferredoxin (Fd) as a scaffold for binding of a ruthenium photosensitizer (PS) and a molecular cobaloxime catalyst (Co). Finally, EPR and transient optical experiments provide direct evidence of a long-lived (>1.5 ms) Ru(III)–Fd–Co(I) charge separated state formed via an electron relay through the Fd [2Fe–2S] cluster, initiating the catalytic cycle for 2H + + 2e - → H 2.

Transitional fossils and the origin of turtles

PubMed Central

Lyson, Tyler R.; Bever, Gabe S.; Bhullar, Bhart-Anjan S.; Joyce, Walter G.; Gauthier, Jacques A.

2010-01-01

The origin of turtles is one of the most contentious issues in systematics with three currently viable hypotheses: turtles as the extant sister to (i) the crocodile–bird clade, (ii) the lizard–tuatara clade, or (iii) Diapsida (a clade composed of (i) and (ii)). We reanalysed a recent dataset that allied turtles with the lizard–tuatara clade and found that the inclusion of the stem turtle Proganochelys quenstedti and the ‘parareptile’ Eunotosaurus africanus results in a single overriding morphological signal, with turtles outside Diapsida. This result reflects the importance of transitional fossils when long branches separate crown clades, and highlights unexplored issues such as the role of topological congruence when using fossils to calibrate molecular clocks. PMID:20534602

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.

Gallium(iii) and iron(iii) complexes of quinolone antimicrobials.

PubMed

Mjos, Katja Dralle; Cawthray, Jacqueline F; Polishchuk, Elena; Abrams, Michael J; Orvig, Chris

2016-08-16

Iron is an essential nutrient for many microbes. According to the "Trojan Horse Hypothesis", biological systems have difficulties distinguishing between Fe(3+) and Ga(3+), which constitutes the antimicrobial efficacy of the gallium(iii) ion. Nine novel tris(quinolono)gallium(iii) complexes and their corresponding iron(iii) analogs have been synthesized and fully characterized. Quinolone antimicrobial agents from three drug generations were used in this study: ciprofloxacin, enoxacin, fleroxacin, levofloxacin, lomefloxacin, nalidixic acid, norfloxacin, oxolinic acid, and pipemidic acid. The antimicrobial efficacy of the tris(quinolono)gallium(iii) complexes was studied against E. faecalis and S. aureus (both Gram-positive), as well as E. coli, K. pneumonia, and P. aeruginosa (all Gram-negative) in direct comparison to the tris(quinolono)iron(iii) complexes and the corresponding free quinolone ligands at various concentrations. For the tris(quinolono)gallium(iii) complexes, no combinational antimicrobial effects between Ga(3+) and the quinolone antimicrobial agents were observed.

Dipicolinate Complexes of Gallium(III) and Lanthanum(III).

PubMed

Weekes, David M; Ramogida, Caterina F; Jaraquemada-Peláez, Maria de Guadalupe; Patrick, Brian O; Apte, Chirag; Kostelnik, Thomas I; Cawthray, Jacqueline F; Murphy, Lisa; Orvig, Chris

2016-12-19

Three dipicolinic acid amine-derived compounds functionalized with a carboxylate (H 3 dpaa), phosphonate (H 4 dppa), and bisphosphonate (H 7 dpbpa), as well as their nonfunctionalized analogue (H 2 dpa), were successfully synthesized and characterized. The 1:1 lanthanum(III) complexes of H 2 dpa, H 3 dpaa, and H 4 dppa, the 1:2 lanthanum(III) complex of H 2 dpa, and the 1:1 gallium(III) complex of H 3 dpaa were characterized, including via X-ray crystallography for [La 4 (dppa) 4 (H 2 O) 2 ] and [Ga(dpaa)(H 2 O)]. H 2 dpa, H 3 dpaa, and H 4 dppa were evaluated for their thermodynamic stability with lanthanum(III) via potentiometric and either UV-vis spectrophotometric (H 3 dpaa) or NMR spectrometric (H 2 dpa and H 4 dppa) titrations, which showed that the carboxylate (H 3 dpaa) and phosphonate (H 4 dppa) containing ligands enhanced the lanthanum(III) complex stability by 3-4 orders of magnitude relative to the unfunctionalized ligand (comparing log β ML and pM values) at physiological pH. In addition, potentiometric titrations with H 3 dpaa and gallium(III) were performed, which gave significantly (8 orders of magnitude) higher thermodynamic stability constants than with lanthanum(III). This was predicted to be a consequence of better size matching between the dipicolinate cavity and gallium(III), which was also evident in the aforementioned crystal structures. Because of a potential link between lanthanum(III) and osteoporosis, the ligands were tested for their bone-directing properties via a hydroxyapatite (HAP) binding assay, which showed that either a phosphonate or bisphosphonate moiety was necessary in order to elicit a chemical binding interaction with HAP. The oral activity of the ligands and their metal complexes was also assessed by experimentally measuring log P o/w values using the shake-flask method, and these were compared to a currently prescribed osteoporosis drug (alendronate). Because of the potential therapeutic applications of the radionuclides

Improved Wavelengths and Oscillator Strengths of Cr III, Co III, and Fe III

NASA Astrophysics Data System (ADS)

Smith, Peter L.; Smillie, D. G.; Pickering, J. C.; Blackwell-Whitehead, R. J.

2008-05-01

Improvements in the resolution, accuracy, and range of spectra obtained by state-of-the-art space- and ground-based astronomical spectrographs have demonstrated a need for corresponding improvements in atomic data. Transition wavelengths with uncertainties of 1 part in 10^7 and oscillator strengths (f-values) with uncertainties of 10 to 15% are needed to accurately interpret modern astrophysical spectra. Our focus has been on spectra of doubly ionized iron group elements that dominate the UV spectra of hot B stars. We report here completion of measurements on Cr III, Co III, Fe III made with a UV high resolution Fourier transform spectrometer (FTS) [J. C. Pickering, Vibrational Spectrosc. 29, 27 (2002)] with a typical wavelength/wavenumber uncertainty of a few parts in 10^8, supplemented by measurements were carried out at the US National Institute of Standards & Technology using their FTS and the Normal Incidence Vacuum (grating) Spectrograph (NIVS). The spectra were analyzed and line lists were produced to give calibrated line wavelengths and relative intensities. Measured wavelengths are, in many cases, an order of magnitude more accurate than previous measurements, and the energy level uncertainties are typically reduced by a factor or 3 more. Summaries of submitted papers on Cr III and Co III will be presented, as will work on improved wavelengths, energy levels, and oscillator strengths for Fe III. Limitations to the method and possible solutions will be discussed. This work is, or has been, supported in part by NASA Grant NAG5-12668; NASA inter-agency agreement W-10255; PPARC; the Royal Society of the UK; and by the Leverhulme Trust.

Global Positioning System III (GPS III)

DTIC Science & Technology

2013-12-01

Galileo satellite navigation system signal, E1. L1C is also compatible with those signals planned for broadcast on Japan’s Quazi-Zenith Satellite...and Galileo constellations, further increasing the accuracy and availability of civil PNT solutions. GPS III December 2013 SAR April 16, 2014...vehicle- level core mate. The overall program continues to make progress on the GPS III Non-Flight Satellite Testbed (GNST), on SV01 development, and

Rapid photooxidation of Sb(III) in the presence of different Fe(III) species

NASA Astrophysics Data System (ADS)

Kong, Linghao; He, Mengchang; Hu, Xingyun

2016-05-01

The toxicity and mobility of antimony (Sb) are strongly influenced by the redox processes associated with Sb. Dissolved iron (Fe) is widely distributed in the environment as different species and plays a significant role in Sb speciation. However, the mechanisms of Sb(III) oxidation in the presence of Fe have remained unclear because of the complexity of Fe and Sb speciation. In this study, the mechanisms of Sb(III) photooxidation in the presence of different Fe species were investigated systematically. The photooxidation of Sb(III) occurred over a wide pH range, from 1 to 10. Oxygen was not a predominant or crucial factor in the Sb(III) oxidation process. The mechanism of Sb(III) photooxidation varied depending on the Fe(III) species. In acidic solution (pH 1-3), dichloro radicals (radCl2-) and hydroxyl radicals (radOH) generated by the photocatalysis of FeCl2+ and FeOH2+ were the main oxidants for Sb(III) oxidation. Fe(III) gradually transformed into the colloid ferric hydroxide (CFH) and ferrihydrite in circumneutral and alkaline solutions (pH 4-10). Photooxidation of Sb(III) occurred through electron transfer from Sb(III) to Fe(III) along with the reduction of Fe(III) to Fe(II) through a ligand-to-metal charge-transfer (LMCT) process. The photocatalysis of different Fe(III) species may play an important role in the geochemical cycle of Sb(III) in surface soil and aquatic environments.

Sparkle model for the calculation of lanthanide complexes: AM1 parameters for Eu(III), Gd(III), and Tb(III).

PubMed

Freire, Ricardo O; Rocha, Gerd B; Simas, Alfredo M

2005-05-02

Our previously defined Sparkle model (Inorg. Chem. 2004, 43, 2346) has been reparameterized for Eu(III) as well as newly parameterized for Gd(III) and Tb(III). The parameterizations have been carried out in a much more extensive manner, aimed at producing a new, more accurate model called Sparkle/AM1, mainly for the vast majority of all Eu(III), Gd(III), and Tb(III) complexes, which possess oxygen or nitrogen as coordinating atoms. All such complexes, which comprise 80% of all geometries present in the Cambridge Structural Database for each of the three ions, were classified into seven groups. These were regarded as a "basis" of chemical ambiance around a lanthanide, which could span the various types of ligand environments the lanthanide ion could be subjected to in any arbitrary complex where the lanthanide ion is coordinated to nitrogen or oxygen atoms. From these seven groups, 15 complexes were selected, which were defined as the parameterization set and then were used with a numerical multidimensional nonlinear optimization to find the best parameter set for reproducing chemical properties. The new parameterizations yielded an unsigned mean error for all interatomic distances between the Eu(III) ion and the ligand atoms of the first sphere of coordination (for the 96 complexes considered in the present paper) of 0.09 A, an improvement over the value of 0.28 A for the previous model and the value of 0.68 A for the first model (Chem. Phys. Lett. 1994, 227, 349). Similar accuracies have been achieved for Gd(III) (0.07 A, 70 complexes) and Tb(III) (0.07 A, 42 complexes). Qualitative improvements have been obtained as well; nitrates now coordinate correctly as bidentate ligands. The results, therefore, indicate that Eu(III), Gd(III), and Tb(III) Sparkle/AM1 calculations possess geometry prediction accuracies for lanthanide complexes with oxygen or nitrogen atoms in the coordination polyhedron that are competitive with present day ab initio/effective core potential

New oxyfluorotellurates(IV): MTeO3F (M = FeIII, GaIII and CrIII).

PubMed

Laval, Jean Paul; Jennene Boukharrata, Nefla; Thomas, Philippe

2008-02-01

The crystal structures of the new isomorphous compounds iron(III) oxyfluorotellurate(IV), FeTeO(3)F, gallium(III) oxyfluorotellurate(IV), GaTeO(3)F, and chromium(III) oxyfluorotellurate(IV), CrTeO(3)F, consist of zigzag chains of MO(4)F(2) distorted octahedra alternately sharing O-O and F-F edges and connected via TeO(3) trigonal pyramids. A full O/F anionic ordering is observed and the electronic lone pair of the Te(IV) cation is stereochemically active.

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

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

An Electron-bifurcating Caffeyl-CoA Reductase*

PubMed Central

Bertsch, Johannes; Parthasarathy, Anutthaman; Buckel, Wolfgang; Müller, Volker

2013-01-01

A low potential electron carrier ferredoxin (E0′ ≈ −500 mV) is used to fuel the only bioenergetic coupling site, a sodium-motive ferredoxin:NAD+ oxidoreductase (Rnf) in the acetogenic bacterium Acetobacterium woodii. Because ferredoxin reduction with physiological electron donors is highly endergonic, it must be coupled to an exergonic reaction. One candidate is NADH-dependent caffeyl-CoA reduction. We have purified a complex from A. woodii that contains a caffeyl-CoA reductase and an electron transfer flavoprotein. The enzyme contains three subunits encoded by the carCDE genes and is predicted to have, in addition to FAD, two [4Fe-4S] clusters as cofactor, which is consistent with the experimental determination of 4 mol of FAD, 9 mol of iron, and 9 mol of acid-labile sulfur. The enzyme complex catalyzed caffeyl-CoA-dependent oxidation of reduced methyl viologen. With NADH as donor, it catalyzed caffeyl-CoA reduction, but this reaction was highly stimulated by the addition of ferredoxin. Spectroscopic analyses revealed that ferredoxin and caffeyl-CoA were reduced simultaneously, and a stoichiometry of 1.3:1 was determined. Apparently, the caffeyl-CoA reductase-Etf complex of A. woodii uses the novel mechanism of flavin-dependent electron bifurcation to drive the endergonic ferredoxin reduction with NADH as reductant by coupling it to the exergonic NADH-dependent reduction of caffeyl-CoA. PMID:23479729

Large Hexadecametallic {Mn(III) -Ln(III) } Wheels: Synthesis, Structural, Magnetic, and Theoretical Characterization.

PubMed

Vignesh, Kuduva R; Langley, Stuart K; Moubaraki, Boujemaa; Murray, Keith S; Rajaraman, Gopalan

2015-11-09

The synthesis, gas sorption studies, magnetic properties, and theoretical studies of new molecular wheels of core type {Mn(III) 8 Ln(III) 8 } (Ln=Dy, Ho, Er, Y and Yb), using the ligand mdeaH2 , in the presence of ortho-toluic or benzoic acid are reported. From the seven wheels studied the {Mn8 Dy8 } and {Mn8 Y8 } analogues exhibit SMM behavior as determined from ac susceptibility experiments in a zero static magnetic field. From DFT calculations a S=16 ground state was determined for the {Mn8 Y8 } complex due to weak ferromagnetic Mn(III) -Mn(III) interactions. Ab initio CASSCF+RASSI-SO calculations on the {Mn8 Dy8 } wheel estimated the Mn(III) -Dy(III) exchange interaction as -0.1 cm(-1) . This weak exchange along with unfavorable single-ion anisotropy of Dy(III) /Mn(III) ions, however, led to the observation of SMM behavior with fast magnetic relaxation. The orientation of the g-anisotropy of the Dy(III) ions is found to be perpendicular to the plane of the wheel and this suggests the possibility of toroidal magnetic moments in the cluster. The {Mn8 Ln8 } clusters reported here are the largest heterometallic Mn(III) Ln(III) wheels and the largest {3d-4f} wheels to exhibit SMM behavior reported to date. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Identification of the Binding Region of the [2Fe-2S] Ferredoxin in Stearoyl-Acyl Carrier Protein Desaturase

PubMed Central

Sobrado, Pablo; Lyle, Karen S.; Kaul, Steven P.; Turco, Michelle M.; Arabshahi, Ida; Marwah, Ashok; Fox, Brian G.

2008-01-01

Stearoyl-acyl carrier protein desaturase (Δ9D) catalyzes the O2 and 2e- dependent desaturation of stearoyl-acyl carrier protein (18:0-ACP) to yield oleoyl-ACP (18:1-ACP). The 2e- are provided by essential interactions with reduced plant-type [2Fe-2S] ferredoxin (Fd). We have investigated the protein-protein interface involved in the Fd-Δ9D complex by use of chemical cross-linking, site-directed mutagenesis, steady-state kinetic approaches and molecular docking studies. Treatment of the different proteins with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide revealed that carboxylate residues from Fd and lysine residues from Δ9D contribute to the cross-linking. The single substitutions of K60A, K56A, and K230A on Δ9D decreased the kcat/KM for Fd by 4-, 22- and 2,400-fold, respectively, as compared to wt Δ9D and a K41A substitution. The double substitution K56A/K60A decreased the kcat/KM for Fd by 250-fold, while the triple mutation K56A/K60A/K230A decreased the kcat/KM for Fd by at least 700,000-fold. These results strongly implicate the triad of K56, K60 and K230 of Δ9D in the formation of a catalytic complex with Fd. Molecular docking studies indicate that electrostatic interactions between K56 and K60 and carboxylate groups on Fd may situate the [2Fe-2S] cluster of Fd near to W62, a surface residue that is structurally conserved in both ribonucleotide reductase and mycobacterial putative acyl-ACP desaturase DesA2. Owing to the considerably larger effects on catalysis, K230 appears to have other contributions to catalysis arising from its positioning in helix-7 and its close spatial location to the diiron center ligands E229 and H232. These results are considered in the light of the presently available models for Fd-mediated electron transfer in Δ9D and other protein-protein complexes. PMID:16605252

Extraction chromatographic separation of Am(III) and Eu(III) by TPEN-immobilized gel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Takeshita, K.; Ogata, T.; Oaki, H.

2013-07-01

A TPEN derivative with 4 vinyl groups, N,N,N',N' -tetrakis-(4-propenyloxy-2-pyridylmethyl)ethylenediamine (TPPEN) was synthesized for the separation of trivalent minor actinides (Am(III)) and lanthanides (Eu(III)). A co-polymer gel with TPPEN and N-isopropylacrylamide (NIPA) showed a high separation factor of Am(III) over Eu(III) (SF[Am/Eu]), which was evaluated to be 26 at pH=5. Thin film of NIPA-TPPEN gel (average thickness: 2-40 nm) was immobilized on the pore surface in porous silica particles (particle diameter : 50 μm, average pore diameter : 50 and 300 nm) and a chromatographic column (diameter: 6 mm, height: 11 mm) packed with the gel-coated particles was prepared. A smallmore » amount of weakly acidic solution (pH=4) containing Am(III) and Eu(III) was supplied in the column and the elution tests of Am(III) and Eu(III) were carried out. Eu(III) was recovered separately by a weakly acidic eluent (pH=4) at 313 K and Am(III) by a highly acidic eluent (pH=2) at 298 K. These results suggest that the contentious separation of minor actinides and lanthanides is attainable by a new extraction chromatographic process with two columns adjusted to 298 K and 313 K. (authors)« less

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. Copyright © 2016 Elsevier Ltd. All rights reserved.

Investigations into the synthesis and fluorescence properties of Eu(III), Tb(III), Sm(III) and Gd(III) complexes of a novel bis- β-diketone-type ligand

NASA Astrophysics Data System (ADS)

Luo, Yi-Ming; Chen, Zhe; Tang, Rui-Ren; Xiao, Lin-Xiang; Peng, Hong-Jian

2008-02-01

A novel bis- β-diketon ligand, 1,1'-(2,6-bispyridyl)bis-3-phenyl-1,3-propane-dione (L), was designed and synthesized and its complexes with Eu(III), Tb(III), Sm(III) and Gd(III) ions were successfully prepared. The ligand and the corresponding metal complexes were characterized by elemental analysis, and infrared, mass and proton nuclear magnetic resonance spectroscopy. Analysis of the IR spectra suggested that each of the lanthanide metal ions coordinated to the ligand via the carbonyl oxygen atoms and the nitrogen atom of the pyridine ring. The fluorescence properties of these complexes in solid state were investigated and it was discovered that all of the lanthanide ions could be sensitized by the ligand (L) to some extent. In particular, the Tb(III) complex was an excellent green-emitter and would be a potential candidate material for applications in organic light-emitting devices (OLEDs) and medical diagnosis.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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.

Spectrophotometric Determination of Chromium (III) with the Disodium Salt of (Ethylenediamine) tetraacetic Acid (Complexon III); DETERMINACION ESPECTROFOTOMETRICA DE CROMO (III) CON LA SAL DISODICA DEL ACIDO ETILEN-DIAMINO-TETRA-ACETICO (COMPLEXONA III)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cellini, R.F.; Valiente, E.A.

1956-01-01

A spectrophotometric method for Cr (III) determination is established: hot and weak acid solutions are treated by disodium (ethylenediamine)tetraacetic acid (complexoneIII) yielding a very stable violet chelate, which follows Beer's law between 1 and 7 gamma Cr(III)/ml. These concentrations are employed in the experiences of this work. The absorption spectrum of Cr(III)-complexone-III has two maximums at 396 and 538 m mu . The maximum at 538 mu m is utilized in this method. Time, temperature, pH, and complexone-III concentration are studied and the best experimental conditions are fixed. (auth)

HscA and HscB stimulate [2Fe-2S] cluster transfer from IscU to apo-ferredoxin in an ATP-dependent reaction†

PubMed Central

Chandramouli, Kala; Johnson, Michael K.

2008-01-01

The role of the Azotobacter vinelandii HscA/HscB co-chaperone system in ISC-mediated iron-sulfur cluster biogenesis has been investigated in vitro by using CD and EPR spectrometry to monitor the effect of HscA, HscB, MgATP, and MgADP on the time course of cluster transfer from [2Fe-2S]IscU to apo-Isc ferredoxin. CD spectra indicate that both HscB and HscA interact with [2Fe-2S] IscU and the rate of cluster transfer was stimulated more than 20-fold in the presence stoichiometric HscA and HscB and excess MgATP. No stimulation was observed in the absence of either HscB or MgATP and cluster transfer was found to be an ATP-dependent reaction based on concomitant phosphate production and the enhanced rates of cluster transfer in the presence of KCl which is known to stimulated HscA ATPase activity. The results demonstrate a role of the ISC HscA/HscB co-chaperone system in facilitating efficient [2Fe-2S] cluster transfer from the IscU scaffold protein to acceptor proteins and that [2Fe-2S] cluster transfer from IscU is an ATP-dependent process. The data are consistent with the proposed regulation of the HscA ATPase cycle by HscB and IscU (Silberg, J. J., Tapley, T. L., Hoff, K. G., and Vickery, L. E. (2004) J. Biol. Chem. 279, 53924-53931), and mechanistic proposals for coupling of the HscA ATPase cycle with cluster transfer from [2Fe-2S]IscU to apo-IscFdx are discussed. PMID:16964969

Redox reactions of V(III) and Cr(III)picolinate complexes in aqueous solutions

NASA Astrophysics Data System (ADS)

Vinayakumar, C. K.; Dey, G. R.; Kishore, K.; Moorthy, P. N.

1996-12-01

Reactions of e aq-, H-atoms, OH, (CH 3) 2COH, and CO 2- radicals with V(III)picolinate and Cr(III)picolinate have been studied by the pulse radiolysis technique. The spectra of V(II)picolinate, V(IV)picolinate, Cr(II)picolinate, OH adduct of Cr(III)picolinate and Cr(IV)picolinate have been obtained and the rate constants of the reactions of various radicals with V(III) and Cr(III)picolinate have been determined. The implications of these results to the chemical decontamination of nuclear reactor systems are discussed.

Quantum chemical study of arsenic (III, V) adsorption on Mn-oxides: implications for arsenic(III) oxidation.

PubMed

Zhu, Mengqiang; Paul, Kristian W; Kubicki, James D; Sparks, Donald L

2009-09-01

Density functional theory (DFT) calculations were used to investigate As(V) and As(III) surface complex structures and reaction energies on both Mn(III) and Mn(IV) sites in an attempt to better understand As(III) oxidation bybirnessite, a layered Mn-dioxide mineral. Edge-sharing dioctahedral Mn(III) and Mn(IV) clusters with different combinations of surface functional groups (>MnOH and >MnOH2) were employed to mimic pH variability. Results show that As(V) adsorption was more thermodynamically favorable than As(III) adsorption on both Mn(III) and Mn(IV) surface sites under simulated acidic pH conditions. Therefore, we propose that As(V) adsorption inhibits As(III) oxidation by blocking adsorption sites. Under simulated acidic pH conditions, Mn(IV) sites exhibited stronger adsorption affinity than Mn(III) sites for both As(III) and As(V). Overall, we hypothesize that Mn(III) sites are less reactive in terms of As(III) oxidation due to their lower affinity for As(III) adsorption, higher potential to be blocked by As(V) complexes, and slower electron transfer rates with adsorbed As(III). Results from this study offer an explanation regarding the experimental observations of Mn(III) accumulation on birnessite and the long residence time of As(III) adsorption complexes on manganite (r-MnOOH) during As(III) oxidation.

SAGE III

Atmospheric Science Data Center

2017-10-27

SAGE III Data and Information The Stratospheric Aerosol and Gas ... on the spacecraft. SAGE III produced L1 and L2 scientific data from 5/07/2002 until 12/31/2005. The second instrument is as an ... Additional Info:  Data Format: HDF-EOS or Big Endian/IEEE Binary SCAR-B Block:  ...

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.

Synthesis, structure, and magnetic characterization of a C3-symmetric Mn(III)3Cr(III) assembly: molecular recognition between a trinuclear Mn(III) triplesalen complex and a fac-triscyano Cr(III) complex.

PubMed

Freiherr von Richthofen, Carl-Georg; Stammler, Anja; Bögge, Hartmut; DeGroot, Marty W; Long, Jeffrey R; Glaser, Thorsten

2009-11-02

The reaction of the tris(tetradentate) triplesalen ligand H(6)talen(t-Bu(2)), which provides three salen-like coordination environments bridged in a meta-phenylene arrangement by a phloroglucinol backbone, with Mn(II) salts under aerobic conditions, affords, in situ, the trinuclear Mn(III) triplesalen complex [(talen(t-Bu(2))){Mn(III)(solv)(n)}(3)](3+). This species then reacts with [(Me(3)tacn)Cr(CN)(3)] to form the tetranuclear complex [{(talen(t-Bu(2)))Mn(III)(3)}{(Me(3)tacn)Cr(CN)(3)}](3+) ([Mn(III)(3)Cr(III)](3+)). The regular ligand folding observed in the trinuclear triplesalen complex preorganizes the three metal ions for the reaction with three facially coordinated nitrogen atoms of [(Me(3)tacn)Cr(CN)(3)]. [{(talen(t-Bu(2)))(Mn(III)(MeOH))(3)}{(Me(3)tacn)Cr(CN)(3)}](ClO(4))(3) (1) was characterized by infrared spectroscopy, elemental analysis, mass spectrometry, electron absorption spectroscopy, and magnetic measurements. The molecular structure was established for the acetate-substituted derivative [{(talen(t-Bu(2)))(Mn(III)(MeOH))(2)(Mn(III)(OAc))}{(Me(3)tacn)Cr(CN)(3)}](ClO(4))(2) (2) by single-crystal X-ray diffraction. Variable-temperature-variable-field and mu(eff) versus T magnetic data have been analyzed in detail by full-matrix diagonalization of the appropriate spin-Hamiltonian, consisting of isotropic exchange, zero-field splitting, and Zeeman interaction components. Satisfactory reproduction of the experimental data has been obtained for the parameters J(Mn-Cr) = -0.12 +/- 0.04 cm(-1), J(Mn-Mn) = -0.70 +/- 0.03 cm(-1), and D(Mn) = -3.0 +/- 0.4 cm(-1). These generate a triply degenerate pseudo S(t) = 7/2 spin manifold, which cannot be appropriately described by a giant spin model and which exhibits a weak easy-axis magnetic anisotropy. This is corroborated by the onset of a frequency-dependent chi'' signal at low temperatures, demonstrating a slow relaxation of the magnetization indicative of 1 being a single-molecule magnet. Comparing the

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. Copyright © 2014 Elsevier GmbH. All rights reserved.

An EGFR wild type-EGFRvIII-HB-EGF feed forward loop regulates the activation of EGFRvIII

PubMed Central

Li, Li; Chakraborty, Sharmistha; Yang, Chin-Rang; Hatanpaa, Kimmo J.; Cipher, Daisha J.; Puliyappadamba, Vineshkumar Thidil; Rehman, Alizeh; Jiwani, Ameena J.; Mickey, Bruce; Madden, Christopher; Raisanen, Jack; Burma, Sandeep; Saha, Debabrata; Wang, Zhixiang; Pingle, Sandeep C.; Kesari, Santosh; Boothman, David A.; Habib, Amyn A.

2014-01-01

EGFRvIII is a key oncogene in glioblastoma (GBM). EGFRvIII results from an in frame deletion in the extracellular domain of EGFR, does not bind ligand, and is thought to be constitutively active. While EGFRvIII dimerization is known to activate EGFRvIII, the factors that drive EGFRvIII dimerization and activation are not well understood. Here we present a new model of EGFRvIII activation and propose that oncogenic activation of EGFRvIII in glioma cells is driven by co-expressed activated EGFR wild type (EGFRwt). Increasing EGFRwt leads to a striking increase in EGFRvIII tyrosine phosphorylation and activation while silencing EGFRwt inhibits EGFRvIII activation. Both the dimerization arm and the kinase activity of EGFRwt are required for EGFRvIII activation. EGFRwt activates EGFRvIII by facilitating EGFRvIII dimerization. We have previously identified HB-EGF, a ligand for EGFRwt, as a gene induced specifically by EGFRvIII. In this study we show that HB-EGF, is induced by EGFRvIII only when EGFRwt is present. Remarkably, altering HB-EGF recapitulates the effect of EGFRwt on EGFRvIII activation. Thus, increasing HB-EGF leads to a striking increase in EGFRvIII tyrosine phosphorylation while silencing HB-EGF attenuates EGFRvIII phosphorylation, suggesting that an EGFRvIII-HB-EGF-EGFRwt feed forward loop regulates EGFRvIII activation. Silencing EGFRwt or HB-EGF leads to a striking inhibition of EGFRvIII induced tumorigenicity, while increasing EGFRwt or HB-EGF levels resulted in accelerated EGFRvIII mediated oncogenicity in an orthotopic mouse model. Furthermore, we demonstrate the existence of this loop in human GBM. Thus, our data demonstrate that oncogenic activation of EGFRvIII in GBM is likely maintained by a continuous EGFRwt-EGFRvIII-HBEGF loop, potentially an attractive target for therapeutic intervention. PMID:24077285

Purification of mutacin III from group III Streptococcus mutans UA787 and genetic analyses of mutacin III biosynthesis genes.

PubMed

Qi, F; Chen, P; Caufield, P W

1999-09-01

Previously, members of our group reported the isolation and characterization of mutacin II from Streptococcus mutans T8 and the genetic analyses of the mutacin II biosynthesis genes (J. Novak, P. W. Caufield, and E. J. Miller, J. Bacteriol. 176:4316-4320, 1994; F. Qi, P. Chen, and P. W. Caufield, Appl. Environ. Microbiol. 65:652-658, 1999; P. Chen, F. Qi, J. Novak, and P. W. Caufield, Appl. Environ. Microbiol. 65:1356-1360, 1999). In this study, we cloned and sequenced the mutacin III biosynthesis gene locus from a group III strain of S. mutans, UA787. DNA sequence analysis revealed eight open reading frames, which we designated mutR, -A, -A', -B, -C, -D, -P, and -T. MutR bears strong homology with MutR of mutacin II, while MutA, -B, -C, -D, -P, and -T are counterparts of proteins in the lantibiotic epidermin group. MutA' has 60% amino acid identity with MutA and therefore appears to be a duplicate of MutA. Insertional inactivation demonstrated that mutA is an essential gene for mutacin III production, while mutA' is not required. Mutacin III was purified to homogeneity by using reverse-phase high-pressure liquid chromatography. N-terminal peptide sequencing of the purified mutacin III determined mutA to be the structural gene for prepromutacin III. The molecular mass of the purified peptide was measured by laser disorption mass spectrophotometry and found to be 2,266.43 Da, consistent with our supposition that mutacin III has posttranslational modifications similar to those of the lantibiotic epidermin.

Alternative Pathway of Metronidazole Activation in Trichomonas vaginalis Hydrogenosomes

PubMed Central

Hrdý, Ivan; Cammack, Richard; Stopka, Pavel; Kulda, Jaroslav; Tachezy, Jan

2005-01-01

Metronidazole and related 5-nitroimidazoles are the only available drugs in the treatment of human urogenital trichomoniasis caused by the protozoan parasite Trichomonas vaginalis. The drugs are activated to cytotoxic anion radicals by their reduction within the hydrogenosomes. It has been established that electrons required for metronidazole activation are released from pyruvate by the activity of pyruvate:ferredoxin oxidoreductase and transferred to the drug by a low-redox-potential carrier, ferredoxin. Here we describe a novel pathway involved in the drug activation within the hydrogenosome. The source of electrons is malate, another major hydrogenosomal substrate, which is oxidatively decarboxylated to pyruvate and CO2 by NAD-dependent malic enzyme. The electrons released during this reaction are transferred from NADH to ferredoxin by NADH dehydrogenase homologous to the catalytic module of mitochondrial complex I, which uses ferredoxin as electron acceptor. Trichomonads acquire high-level metronidazole resistance only after both pyruvate- and malate-dependent pathways of metronidazole activation are eliminated from the hydrogenosomes. PMID:16304169

Three Diagnostic Systems for Autism: DSM-III, DSM-III-R, and ICD-10.

ERIC Educational Resources Information Center

Volkmar, Fred R.; And Others

1992-01-01

This paper compared clinicians' diagnosis and DSM-III (Diagnostic and Statistical Manual), DSM-III-R (Revised), and ICD-10 (International Classification of Diseases) diagnoses of 52 individuals with autism and 62 nonautistic, developmentally disordered individuals. The DSM-III-R system overdiagnosed the presence of autism, and ICD-10 closely…

Development of a C3-symmetric benzohydroxamate tripod: Trimetallic complexation with Fe(III), Cr(III) and Al(III)

NASA Astrophysics Data System (ADS)

Baral, Minati; Gupta, Amit; Kanungo, B. K.

2016-06-01

The design, synthesis and physicochemical characterization of a C3-symmetry Benzene-1,3,5-tricarbonylhydroxamate tripod, noted here as BTHA, are described. The chelator was built from a benzene as an anchor, symmetrically extended by three hydroxamate as ligating moieties, each bearing O, O donor sites. A combination of absorption spectrophotometry, potentiometry and theoretical investigations are used to explore the complexation behavior of the ligand with some trivalent metal ions: Fe(III), Cr(III), and Al(III). Three protonation constants were calculated for the ligand in a pH range of 2-11 in a highly aqueous medium (9:1 H2O: DMSO). A high rigidity in the molecular structure restricts the formation of 1:1 (M/L) metal encapsulation but shows a high binding efficiency for a 3:1 metal ligand stoichiometry giving formation constant (in β unit) 28.73, 26.13 and 19.69 for [M3L]; Mdbnd Fe(III), Al(III) and Cr(III) respectively, and may be considered as an efficient Fe-carrier. The spectrophotometric study reveals of interesting electronic transitions occurred during the complexation. BTHA exhibits a peak at 238 nm in acidic pH and with the increase of pH, a new peak appeared at 270 nm. A substantial shifting in both of the peaks in presence of the metal ions implicates a s coordination between ligand and metal ions. Moreover, complexation of BTHA with iron shows three distinct colors, violet, reddish orange and yellow in different pH, enables the ligand to be considered for the use as colorimetric sensor.

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

PubMed Central

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. PMID:26598971

Deletion of nfnAB in Thermoanaerobacterium saccharolyticum and Its Effect on Metabolism

DOE PAGES

Lo, Jonathan; Zheng, Tianyong; Olson, Daniel G.; ...

2015-06-29

NfnAB catalyzes the reversible transfer of electrons from reduced ferredoxin and NADH to 2 NADP +. The NfnAB complex has been hypothesized to be the main enzyme for ferredoxin oxidization in strains of Thermoanaerobacterium saccharolyticum engineered for increased ethanol production. NfnAB complex activity was detectable in crude cell extracts of T. saccharolyticum. In this paper, activity was also detected using activity staining of native PAGE gels. The nfnAB gene was deleted in different strains of T. saccharolyticum to determine its effect on end product formation. In wild-type T. saccharolyticum, deletion of nfnAB resulted in a 46% increase in H 2more » formation but otherwise little change in other fermentation products. In two engineered strains with 80% theoretical ethanol yield, loss of nfnAB caused two different responses: in one strain, ethanol yield decreased to about 30% of the theoretical value, while another strain had no change in ethanol yield. Biochemical analysis of cell extracts showed that the ΔnfnAB strain with decreased ethanol yield had NADPH-linked alcohol dehydrogenase (ADH) activity, while the ΔnfnAB strain with unchanged ethanol yield had NADH-linked ADH activity. Deletion of nfnAB caused loss of NADPH-linked ferredoxin oxidoreductase activity in all cell extracts. Significant NADH-linked ferredoxin oxidoreductase activity was seen in all cell extracts, including those that had lost nfnAB. This suggests that there is an unidentified NADH:ferredoxin oxidoreductase (distinct from nfnAB) playing a role in ethanol formation. The NfnAB complex plays a key role in generating NADPH in a strain that had become reliant on NADPH-ADH activity. Importance: Thermophilic anaerobes that can convert biomass-derived sugars into ethanol have been investigated as candidates for biofuel formation. Many anaerobes have been genetically engineered to increase biofuel formation; however, key aspects of metabolism remain unknown and poorly understood. One

A Paramagnetic Copper(III) Complex Containing an Octahedral CuIII S6 Coordination Polyhedron.

PubMed

Krebs, Carsten; Glaser, Thorsten; Bill, Eckhard; Weyhermüller, Thomas; Meyer-Klaucke, Wolfram; Wieghardt, Karl

1999-02-01

Only the second octahedral, paramagnetic copper(III) complex (S=1) has now been synthesized and characterized. Six thiolato bridging ligands in the heterotrinuclear species [LCo III Cu III Co III L](ClO 4 ) 3 ⋅2 Me 2 CO (L=1,4,7-tris(4-tert-butyl-2-sulfidobenzyl)-1,4,7-triazacyclononane) stabilize this rare electron configuration. A section of the structure of the reduced form (Cu II , S=½) is shown. XAS, EXAFS, and EPR spectroscopy prove unambiguously that the one-electron oxidation to the copper(III) is metal- rather than ligand-centered. © 1999 WILEY-VCH Verlag GmbH, Weinheim, Fed. Rep. of Germany.

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.

Structural Characterization of Am(III)- and Pu(III)-DOTA Complexes.

PubMed

Audras, Matthieu; Berthon, Laurence; Berthon, Claude; Guillaumont, Dominique; Dumas, Thomas; Illy, Marie-Claire; Martin, Nicolas; Zilbermann, Israel; Moiseev, Yulia; Ben-Eliyahu, Yeshayahu; Bettelheim, Armand; Cammelli, Sebastiano; Hennig, Christoph; Moisy, Philippe

2017-10-16

The complexation of 1,4,7,10-tetrazacyclodecane-1,4,7,10-tetraacetic acid (DOTA) ligand with two trivalent actinides (Am 3+ and Pu 3+ ) was investigated by UV-visible spectrophotometry, NMR spectroscopy, and extended X-ray absorption fine structure in conjunction with computational methods. The complexation process of these two cations is similar to what has been previously observed with lanthanides(III) of similar ionic radius. The complexation takes place in different steps and ends with the formation of a (1:1) complex [(An(III)DOTA)(H 2 O)] - , where the cation is bonded to the nitrogen atoms of the ring, the four carboxylate arms, and a water molecule to complete the coordination sphere. The formation of An(III)-DOTA complexes is faster than the Ln(III)-DOTA systems of equivalent ionic radius. Furthermore, it is found that An-N distances are slightly shorter than Ln-N distances. Theoretical calculations showed that the slightly higher affinity of DOTA toward Am over Nd is correlated with slightly enhanced ligand-to-metal charge donation arising from oxygen and nitrogen atoms.

Synthesis, structure, luminescent, and magnetic properties of carbonato-bridged Zn(II)2Ln(III)2 complexes [(μ4-CO3)2{Zn(II)L(n)Ln(III)(NO3)}2] (Ln(III) = Gd(III), Tb(III), Dy(III); L(1) = N,N'-bis(3-methoxy-2-oxybenzylidene)-1,3-propanediaminato, L(2) = N,N'-bis(3-ethoxy-2-oxybenzylidene)-1,3-propanediaminato).

PubMed

Ehama, Kiyomi; Ohmichi, Yusuke; Sakamoto, Soichiro; Fujinami, Takeshi; Matsumoto, Naohide; Mochida, Naotaka; Ishida, Takayuki; Sunatsuki, Yukinari; Tsuchimoto, Masanobu; Re, Nazzareno

2013-11-04

Carbonato-bridged Zn(II)2Ln(III)2 complexes [(μ4-CO3)2{Zn(II)L(n)Ln(III)(NO3)}2]·solvent were synthesized through atmospheric CO2 fixation reaction of [Zn(II)L(n)(H2O)2]·xH2O, Ln(III)(NO3)3·6H2O, and triethylamine, where Ln(III) = Gd(III), Tb(III), Dy(III); L(1) = N,N'-bis(3-methoxy-2-oxybenzylidene)-1,3-propanediaminato, L(2) = N,N'-bis(3-ethoxy-2-oxybenzylidene)-1,3-propanediaminato. Each Zn(II)2Ln(III)2 structure possessing an inversion center can be described as two di-μ-phenoxo-bridged {Zn(II)L(n)Ln(III)(NO3)} binuclear units bridged by two carbonato CO3(2-) ions. The Zn(II) ion has square pyramidal coordination geometry with N2O2 donor atoms of L(n) and one oxygen atom of a bridging carbonato ion at the axial site. Ln(III) ion is coordinated by nine oxygen atoms consisting of four from the deprotonated Schiff-base L(n), two from a chelating nitrate, and three from two carbonate groups. The temperature-dependent magnetic susceptibilities in the range 1.9-300 K, field-dependent magnetization from 0 to 5 T at 1.9 K, and alternating current magnetic susceptibilities under the direct current bias fields of 0 and 1000 Oe were measured. The magnetic properties of the Zn(II)2Ln(III)2 complexes are analyzed on the basis of the dicarbonato-bridged binuclear Ln(III)-Ln(III) structure, as the Zn(II) ion with d(10) electronic configuration is diamagnetic. ZnGd1 (L(1)) and ZnGd2 (L(2)) show a ferromagnetic Gd(III)-Gd(III) interaction with J(Gd-Gd) = +0.042 and +0.028 cm(-1), respectively, on the basis of the Hamiltonian H = -2J(Gd-Gd)ŜGd1·ŜGd2. The magnetic data of the Zn(II)2Ln(III)2 complexes (Ln(III) = Tb(III), Dy(III)) were analyzed by a spin Hamiltonian including the crystal field effect on the Ln(III) ions and the Ln(III)-Ln(III) magnetic interaction. The Stark splitting of the ground state was so evaluated, and the energy pattern indicates a strong easy axis (Ising type) anisotropy. Luminescence spectra of Zn(II)2Tb(III)2 complexes were observed, while those

NMR and TRLFS studies of Ln(iii) and An(iii) C5-BPP complexes.

PubMed

Adam, Christian; Beele, Björn B; Geist, Andreas; Müllich, Udo; Kaden, Peter; Panak, Petra J

2015-02-01

C5-BPP is a highly efficient N-donor ligand for the separation of trivalent actinides, An(iii), from trivalent lanthanides, Ln(iii). The molecular origin of the selectivity of C5-BPP and many other N-donor ligands of the BTP-type is still not entirely understood. We present here the first NMR studies on C5-BPP Ln(iii) and An(iii) complexes. C5-BPP is synthesized with 10% 15 N labeling and characterized by NMR and LIFDI-MS methods. 15 N NMR spectroscopy gives a detailed insight into the bonding of C5-BPP with lanthanides and Am(iii) as a representative for trivalent actinide cations, revealing significant differences in 15 N chemical shift for coordinating nitrogen atoms compared to Ln(iii) complexes. The temperature dependence of NMR chemical shifts observed for the Am(iii) complex indicates a weak paramagnetism. This as well as the observed large chemical shift for coordinating nitrogen atoms show that metal-ligand bonding in Am(C5-BPP) 3 has a larger share of covalence than in lanthanide complexes, confirming earlier studies. The Am(C5-BPP) 3 NMR sample is furthermore spiked with Cm(iii) and characterized by time-resolved laser fluorescence spectroscopy (TRLFS), yielding important information on the speciation of trace amounts of minor complex species.

Purification of chicken carbonic anhydrase isozyme-III (CA-III) and its measurement in White Leghorn chickens.

PubMed

Nishita, Toshiho; Tomita, Yuichiro; Yorifuji, Daisuke; Orito, Kensuke; Ochiai, Hideharu; Arishima, Kazuyosi

2011-11-26

The developmental profile of chicken carbonic anhydrase-III (CA-III) blood levels has not been previously determined or reported. We isolated CA-III from chicken muscle and investigated age-related changes in the levels of CA-III in blood. CA-III was purified from chicken muscle. The levels of CA-III in plasma and erythrocytes from 278 female chickens (aged 1-93 weeks) and 68 male chickens (aged 3-59 weeks) were determined by ELISA. The mean level of CA-III in female chicken erythrocytes (1 week old) was 4.6 μg/g of Hb, and the CA-III level did not change until 16 weeks of age. The level then increased until 63 weeks of age (11.8 μg/g of Hb), decreased to 4.7 μg/g of Hb at 73 weeks of age, and increased again until 93 weeks of age (8.6 μg/g of Hb). The mean level of CA-III in erythrocytes from male chickens (3 weeks old) was 2.4 μg/g of Hb, and this level remained steady until 59 weeks of age. The mean plasma level of CA-III in 1-week-old female chickens was 60 ng/mL, and this level was increased at 3 weeks of age (141 ng/mL) and then remained steady until 80 weeks of age (122 ng/mL). The mean plasma level of CA-III in 3-week-old male chickens was 58 ng/mL, and this level remained steady until 59 weeks of age. We observed both developmental changes and sex differences in CA-III concentrations in White Leghorn (WL) chicken erythrocytes and plasma. Simple linear regression analysis showed a significant association between the erythrocyte CA-III level and egg-laying rate in WL-chickens 16-63 weeks of age (p < 0.01).

Insight into the Extraction Mechanism of Americium(III) over Europium(III) with Pyridylpyrazole: A Relativistic Quantum Chemistry Study.

PubMed

Kong, Xiang-He; Wu, Qun-Yan; Wang, Cong-Zhi; Lan, Jian-Hui; Chai, Zhi-Fang; Nie, Chang-Ming; Shi, Wei-Qun

2018-05-10

Separation of trivalent actinides (An(III)) and lanthanides (Ln(III)) is one of the most important steps in spent nuclear fuel reprocessing. However, it is very difficult and challenging to separate them due to their similar chemical properties. Recently the pyridylpyrazole ligand (PypzH) has been identified to show good separation ability toward Am(III) over Eu(III). In this work, to explore the Am(III)/Eu(III) separation mechanism of PypzH at the molecular level, the geometrical structures, bonding nature, and thermodynamic behaviors of the Am(III) and Eu(III) complexes with PypzH ligands modified by alkyl chains (Cn-PypzH, n = 2, 4, 8) have been systematically investigated using scalar relativistic density functional theory (DFT). According to the NBO (natural bonding orbital) and QTAIM (quantum theory of atoms in molecules) analyses, the M-N bonds exhibit a certain degree of covalent character, and more covalency appears in Am-N bonds compared to Eu-N bonds. Thermodynamic analyses suggest that the 1:1 extraction reaction, [M(NO 3 )(H 2 O) 6 ] 2+ + PypzH + 2NO 3 - → M(PypzH)(NO 3 ) 3 (H 2 O) + 5H 2 O, is the most suitable for Am(III)/Eu(III) separation. Furthermore, the extraction ability and the Am(III)/Eu(III) selectivity of the ligand PypzH is indeed enhanced by adding alkyl-substituted chains in agreement with experimental observations. Besides this, the nitrogen atom of pyrazole ring plays a more significant role in the extraction reactions related to Am(III)/Eu(III) separation compared to that of pyridine ring. This work could identify the mechanism of the Am(III)/Eu(III) selectivity of the ligand PypzH and provide valuable theoretical information for achieving an efficient Am(III)/Eu(III) separation process for spent nuclear fuel reprocessing.

Unmasking materialistic depression as a mental health problem: its effect on depression and materialism in an African-United States undergraduate sample.

PubMed

Azibo, Daudi Ajani ya

2013-09-05

Misdiagnosis of African-U.S. persons is argued to be a built-in characteristic of Western-based assessment requiring augmentation with culture-focused input where possible. Regarding depression, materialistic depression is explained as an African-centered African-U.S. culture-focused construct of masked depression. Materialistic depression symptomatology is presented. Materialism orientation is postulated to necessarily be associated with materialistic depression. 144 undergraduates, 37 male (25.7%) and 107 female (74.3%), average age of 21 completed the Zung Self-rating Depression Scale, the depression subscale of the Symptom Checklist 90-R, the materialism subscale of the Cultural Misorientation Scale, and the Materialistic Depression Quiz. Contrasting high versus lower scoring MDQ groups on both depression scores produced reliable t-tests (p<.017). One-way ANOVA on materialism scores with high, medium, low MDQ groups was reliable (p<.017). The sample precluded generalization to clinically depressed and non-college African-U.S. populations. Using the Materialistic Depression Quiz, high scorers versus medium and low scorers had greater depression scores on two depression measures and greater materialism scores. Materialistic depression appears a masked form of depression not to be overlooked. Copyright © 2013 Elsevier B.V. All rights reserved.

Ancient DNA from Nubian and Somali wild ass provides insights into donkey ancestry and domestication

PubMed Central

Kimura, Birgitta; Marshall, Fiona B.; Chen, Shanyuan; Rosenbom, Sónia; Moehlman, Patricia D.; Tuross, Noreen; Sabin, Richard C.; Peters, Joris; Barich, Barbara; Yohannes, Hagos; Kebede, Fanuel; Teclai, Redae; Beja-Pereira, Albano; Mulligan, Connie J.

2011-01-01

Genetic data from extant donkeys (Equus asinus) have revealed two distinct mitochondrial DNA haplogroups, suggestive of two separate domestication events in northeast Africa about 5000 years ago. Without distinct phylogeographic structure in domestic donkey haplogroups and with little information on the genetic makeup of the ancestral African wild ass, however, it has been difficult to identify wild ancestors and geographical origins for the domestic mitochondrial clades. Our analysis of ancient archaeological and historic museum samples provides the first genetic information on the historic Nubian wild ass (Equus africanus africanus), Somali wild ass (Equus africanus somaliensis) and ancient donkey. The results demonstrate that the Nubian wild ass was an ancestor of the first donkey haplogroup. In contrast, the Somali wild ass has considerable mitochondrial divergence from the Nubian wild ass and domestic donkeys. These findings resolve the long-standing issue of the role of the Nubian wild ass in the domestication of the donkey, but raise new questions regarding the second ancestor for the donkey. Our results illustrate the complexity of animal domestication, and have conservation implications for critically endangered Nubian and Somali wild ass. PMID:20667880

Ancient DNA from Nubian and Somali wild ass provides insights into donkey ancestry and domestication.

PubMed

Kimura, Birgitta; Marshall, Fiona B; Chen, Shanyuan; Rosenbom, Sónia; Moehlman, Patricia D; Tuross, Noreen; Sabin, Richard C; Peters, Joris; Barich, Barbara; Yohannes, Hagos; Kebede, Fanuel; Teclai, Redae; Beja-Pereira, Albano; Mulligan, Connie J

2011-01-07

Genetic data from extant donkeys (Equus asinus) have revealed two distinct mitochondrial DNA haplogroups, suggestive of two separate domestication events in northeast Africa about 5000 years ago. Without distinct phylogeographic structure in domestic donkey haplogroups and with little information on the genetic makeup of the ancestral African wild ass, however, it has been difficult to identify wild ancestors and geographical origins for the domestic mitochondrial clades. Our analysis of ancient archaeological and historic museum samples provides the first genetic information on the historic Nubian wild ass (Equus africanus africanus), Somali wild ass (Equus africanus somaliensis) and ancient donkey. The results demonstrate that the Nubian wild ass was an ancestor of the first donkey haplogroup. In contrast, the Somali wild ass has considerable mitochondrial divergence from the Nubian wild ass and domestic donkeys. These findings resolve the long-standing issue of the role of the Nubian wild ass in the domestication of the donkey, but raise new questions regarding the second ancestor for the donkey. Our results illustrate the complexity of animal domestication, and have conservation implications for critically endangered Nubian and Somali wild ass.

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,"…

A binuclear Mn(III) complex of a scorpiand-like ligand displaying a single unsupported Mn(III)-O-Mn(III) bridge.

PubMed

Blasco, Salvador; Cano, Joan; Clares, M Paz; García-Granda, Santiago; Doménech, Antonio; Jiménez, Hermas R; Verdejo, Begoña; Lloret, Francesc; García-España, Enrique

2012-11-05

The crystal structure of a binuclear Mn(III) complex of a scorpiand-like ligand (L) displays an unsupported single oxo bridging ligand with a Mn(III)-O-Mn(III) angle of 174.7°. Magnetic susceptibility measurements indicate strong antiferromagnetic coupling between the two metal centers. DFT calculations have been carried out to understand the magnetic behavior and to analyze the nature of the observed Jahn-Teller distortion. Paramagnetic (1)H NMR has been applied to rationalize the formation and magnetic features of the complexes formed in solution.

SAGE III-ISS

Atmospheric Science Data Center

2017-12-27

SAGE III-ISS Data and Information Launched on February 19, 2017 on a SpaceX ... vertical profiles of the stratosphere and mesosphere. The data provided by SAGE III-ISS includes key components of atmospheric ... Additional Info:  Data Format: HDF4 or Big Endian/IEEE Binary SCAR-B Block:  ...

Sparkle/AM1 Parameters for the Modeling of Samarium(III) and Promethium(III) Complexes.

PubMed

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

2006-01-01

The Sparkle/AM1 model is extended to samarium(III) and promethium(III) complexes. A set of 15 structures of high crystallographic quality (R factor < 0.05 Å), with ligands chosen to be representative of all samarium complexes in the Cambridge Crystallographic Database 2004, CSD, with nitrogen or oxygen directly bonded to the samarium ion, was used as a training set. In the validation procedure, we used a set of 42 other complexes, also of high crystallographic quality. The results show that this parametrization for the Sm(III) ion is similar in accuracy to the previous parametrizations for Eu(III), Gd(III), and Tb(III). On the other hand, promethium is an artificial radioactive element with no stable isotope. So far, there are no promethium complex crystallographic structures in CSD. To circumvent this, we confirmed our previous result that RHF/STO-3G/ECP, with the MWB effective core potential (ECP), appears to be the most efficient ab initio model chemistry in terms of coordination polyhedron crystallographic geometry predictions from isolated lanthanide complex ion calculations. We thus generated a set of 15 RHF/STO-3G/ECP promethium complex structures with ligands chosen to be representative of complexes available in the CSD for all other trivalent lanthanide cations, with nitrogen or oxygen directly bonded to the lanthanide ion. For the 42 samarium(III) complexes and 15 promethium(III) complexes considered, the Sparkle/AM1 unsigned mean error, for all interatomic distances between the Ln(III) ion and the ligand atoms of the first sphere of coordination, is 0.07 and 0.06 Å, respectively, a level of accuracy comparable to present day ab initio/ECP geometries, while being hundreds of times faster.

The GKSS beamlines at PETRA III and DORIS III

NASA Astrophysics Data System (ADS)

Haibel, A.; Beckmann, F.; Dose, T.; Herzen, J.; Utcke, S.; Lippmann, T.; Schell, N.; Schreyer, A.

2008-08-01

Due to the high brilliance of the new storage ring PETRA III at DESY in Hamburg, the low emittance of 1 nmrad and the high fraction of coherent photons also in the hard X-ray range extremely intense and sharply focused X-ray light will be provided. These advantages of the beam fulfill excellently the qualifications for the planned Imaging BeamLine IBL and the High Energy Materials Science Beamline (HEMS) at PETRA III, i.e. for absorption tomography, phase enhanced and phase contrast experiments, for diffraction, for nano focusing, for nano tomography, and for high speed or in-situ experiments with highest spatial resolution. The existing HARWI II beamline at the DORIS III storage ring at DESY completes the GKSS beamline concept with setups for high energy tomography (16-150 keV) and diffraction (16-250 keV), characterized by a large field of view and an excellent absorption contrast with spatial resolutions down to 2 μm.

Occurrence and Speciation of Polymeric Chromium(III), Monomeric Chromium(III) and Chromium(VI) in Environmental Samples

PubMed Central

HU, LIGANG; CAI, YONG; JIANG, GUIBIN

2016-01-01

Laboratory experiments suggest that polymeric Cr(III) could exist in aqueous solution for a relative long period of time. However, the occurrence of polymeric Cr(III) has not been reported in environmental media due partially to the lack of method for speciating polymeric Cr. We observed an unknown Cr species during the course of study on speciation of Cr in the leachates of chromated-copper-arsenate (CCA)-treated wood. Efforts were made to identify structure of the unknown Cr species. Considering the forms of Cr existed in the CCA-treated woods, we mainly focused our efforts to determine if the unknown species were polymeric Cr(III), complex of Cr/As or complex of Cr with dissolved organic matter (DOM). In order to evaluate whether polymeric Cr(III) largely exist in wood leachates, high performance liquid chromatography coupled with inductively coupled mass spectrometry (HPLC-ICPMS was used) for simultaneous speciation of monomeric Cr(III), polymeric Cr(III), and Cr(VI). In addition to wood leachates where polymeric Cr (III) ranged from 39.1 to 67.4 %, occurrence of the unknown Cr species in other environmental matrices, including surface waters, tap and waste waters, was also investigated. It was found that polymeric Cr(III) could exist in environmental samples containing μg/L level of Cr, at a level up to 60% of total Cr, suggesting that polymeric Cr(III) could significantly exist in natural environments. Failure in quantifying polymeric Cr(III) would lead to the underestimation of total Cr and bias in Cr speciation. The environmental implication of the presence of polymeric Cr(III) species in the environment deserves further study. PMID:27156211

Properties of Decameter IIIb-III Pairs

NASA Astrophysics Data System (ADS)

Melnik, V. N.; Brazhenko, A. I.; Frantsuzenko, A. V.; Dorovskyy, V. V.; Rucker, H. O.

2018-02-01

A large number of Type IIIb-III pairs, in which the first component is a Type IIIb burst and the second one is a Type III burst, are often recorded during decameter Type III burst storms. From the beginning of their observation, the question of whether the components of these pairs are the first and the second harmonics of radio emission or not has remained open. We discuss properties of decameter IIIb-III pairs in detail to answer this question. The components of these pairs, Type IIIb bursts and Type III bursts, have essentially different durations and polarizations. At the same time their frequency drift rates are rather close, provided that the drift rates of Type IIIb bursts are a little larger those of Type III bursts at the same frequency. Frequency ratios of the bursts at the same moment are close to two. This points at a harmonic connection of the components in IIIb-III pairs. At the same time there was a serious difficulty, namely why the first harmonic had fine frequency structure in the form of striae and the second harmonic did not have it. Recently Loi, Cairns, and Li ( Astrophys. J. 790, 67, 2014) succeeded in solving this problem. The physical aspects of observational properties of decameter IIIb-III pairs are discussed and pros and cons of harmonic character of Type IIIb bursts and Type III bursts in IIIb-III pairs are presented. We conclude that practically all properties of the IIIb-III pair components can be understood in the framework of the harmonic relation of the components of the IIIb-III pairs.

Optical and relaxometric properties of monometallic (Eu(III), Tb(III), Gd(III)) and heterobimetallic (Re(I)/Gd(III)) systems based on a functionalized bipyridine-containing acyclic ligand.

PubMed

Leygue, Nadine; Boulay, Alexandre; Galaup, Chantal; Benoist, Eric; Laurent, Sophie; Vander Elst, Luce; Mestre-Voegtlé, Béatrice; Picard, Claude

2016-05-17

A series of lanthanide complexes of [LnL(H2O)](2-) composition where Ln = Eu(III), Tb(III) or Gd(III) has been studied for determining their photophysical and relaxometric properties in aqueous solution. The bifunctional ligand L (H5BPMNTA) is an acyclic chelator based on a central functionalized 2,2'-bipyridine core and two iminodiacetate coordinating arms. The mono-aqua Eu(III) and Tb(III) complexes display attractive spectroscopic properties with an excitation wavelength at 316 nm, similar excited state lifetimes and overall quantum yields (in the ranges 0.5-0.6 ms and 10-13%, respectively) in Tris buffer (pH 7.4). The proton longitudinal relaxivity, r1, of the Gd(III) complex is 4.4 mM(-1) s(-1) at 20 MHz and 310 K, which is comparable to that of the clinically used Gd-DTPA (Magnevist®). Interestingly, the water exchange rate between the coordination site and the bulk solvent is very fast (Kex = 2.6 × 10(8) s(-1) at 310 K). The ability of the complex to bind non-covalently to human serum albumin (HSA) was also examined by relaxometric measurements. We also report the synthesis and properties of a bimetallic complex based on Gd-BPMNTA and Re(I)(bpy)(CO)3 components. In this system, the Re core exhibits interesting photophysical properties (λem = 588 nm, Φ = 1.4%) and the Gd-BPMNTA core displays improved relaxivity (r1 = 6.6 mM(-1) s(-1) at 20 MHz and 310 K), due to an increase of the rotational correlation time. Besides these appealing optical and relaxometric properties, the presence of a reactive function on the structure proposes this potential dual imaging probe for conjugation to biomolecules or nanomaterials.

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. Copyright © 2016 Elsevier B.V. All rights reserved.

Formate Dehydrogenase from Clostridium acidiurici

PubMed Central

Kearny, James J.; Sagers, Richard D.

1972-01-01

Partial purification of formate dehydrogenase from Clostridium acidiurici has been accomplished, and some properties of the enzyme have been determined. The molecular weight of the protein is at least 200,000 daltons. The enzyme showed marked instability to freezing and thawing and was inhibited strongly by oxygen and by light. Such inhibition was not reversed by incubation in the presence of thiol compounds. Cyanide inhibited the enzyme 90% at 0.1 mm concentrations, but ethylenediaminetetraacetate produced only slight inhibition at concentrations as high as 50 mm. The purified enzyme showed no ferredoxin activity in the Clostridium pasteurianum clastic system during pyruvate oxidation. Crude preparations of the enzyme could be coupled through ferredoxin to the reduction of nicotinamide adenine dinucleotide during formate oxidation, but the purified enzyme could not catalyze the reduction of pyridine nucleotides by formate in the presence of ferredoxin. Formate oxidation with the purified enzyme was readily coupled to benzyl viologen reduction, in which case ferredoxin was not required. An exchange between formate and bicarbonate was catalyzed by both crude and purified preparations of the enzyme, but the net synthesis of formate from CO2 was not accomplished. PMID:4333376

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.

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.

Removal of arsenic from water using manganese (III) oxide: Adsorption of As(III) and As(V).

PubMed

Babaeivelni, Kamel; Khodadoust, Amid P

2016-01-01

Removal of arsenic from water was evaluated with manganese (III) oxide (Mn2O3) as adsorbent. Adsorption of As(III) and As(V) onto Mn2O3 was favorable according to the Langmuir and Freundlich adsorption equilibrium equations, while chemisorption of arsenic occurred according to the Dubinin-Radushkevich equation. Adsorption parameters from the Langmuir, Freundlich, and Temkin equations showed a greater adsorption and removal of As(III) than As(V) by Mn2O3. Maximum removal of As(III) and As(V) occurred at pH 3-9 and at pH 2, respectively, while removal of As(V) in the pH range of 6-9 was 93% (pH 6) to 61% (pH 9) of the maximum removal. Zeta potential measurements for Mn2O3 in As(III) was likely converted to As(V) solutions indicated that As(III) was likely converted to As(V) on the Mn2O3 surface at pH 3-9. Overall, the effective Mn2O3 sorbent rapidly removed As(III) and As(V) from water in the pH range of 6-9 for natural waters.

Thioredoxins in evolutionarily primitive organisms

NASA Technical Reports Server (NTRS)

Buchanan, B. B.

1986-01-01

Thioredoxins are low molecular weight redox proteins, alternating between the S-S (oxidized) and SH (reduced) states, that function in a number of biochemical processes, including DNA synthesis, DNA replication, and enzyme regulation. Until recently, reduced ferredoxin was known to serve as the source of reducing power for the reduction of thioredoxins only in oxygenic photosynthetic cells. In all other organisms, the source of hydrogen (electrons) for thioredoxin reduction was considered to be NADPH. It was found that Clostridium pasteurianum, an anaerobic organism normally living in the soil unexposed to light, resembles photosynthetic cells in using ferredoxin for the reduction of thioredoxin. The results reveal the existence of a pathway in which ferredoxin, provides the reducing power for the reduction of thioredoxin via the flavoprotein enzyme, ferredoxinthioredoxin reductase. In related studies, it was found that Chromatium vinosum, an anaerobic photosynthetic purple sulfur bacterium, resembles evolutionarily more advanced micro-organisms in having an NADP-thioredoxin system composed of a single thioredoxin which is reduced by NADPH via NADP-thioredoxin reductase. The adoption of the NADP-thioredoxin system by Chromatium seems appropriate in view of evidence tha the organi sm utilizes ATP-driven reverse electron transport. Finally, results of research directed towards the identification of target enzymes of the ferredoxin/thioredoxin system in a cyanobacterium (Nostoc muscorum), show that thioredoxin-linked photosynthetic enzymes of cyanobateria are similar to those of chloroplasts. It now seems that the ferredoxin/thioredoxin system functions in regulating CO2 assimilation via the reductive pentose phosphate cycle in oxygenic but not anoxygenic photosynthetic cells.

Electron spin resonance studies of the ovary of the rat

NASA Astrophysics Data System (ADS)

Andersen, Roy S.; Curtis, Joseph C.

1988-11-01

Electron spin resonance spectra of rat ovaries, isolated ovarian compartments, and ovarian subcellular fractions were compared with spectra of rat adrenals. Rat ovaries were found to exhibit ESR signals similar to those previously described in studies of mammalian adrenal and testis. Observations were made at 113 K in an anaerobic environment. ESR signals of the low-spin ferric cytochrome P-450, the non-heme protein ferredoxin, and the non-heme glycoprotein transferrin were consistently observed in whole ovaries. The first two signals were detected in mitochondrial fractions isolated from ovaries, while only cytochrome P-450 was detected in microsomal fractions. Signals from ferredoxin and cytochrome P-450 were also consistently observed in both whole adrenals and adrenal mitochondrial fractions. However, in the microsomal fraction only cytochrome P-450 was present. The g values for the cytochrome P-450 and ferredoxin signals found in this study of ovaries were identical to those previously reported and also found in this study in spectra of rat adrenals. The concentration of ferredoxin per milligram wet mass in rat ovaries appears to be only one-sixth of that in the rat adrenal. The concentration of cytochrome P-450 appears to be only one-ninth of that in the adrenal. Signals from ferredoxin were detected in all ovarian compartments except granulosa cells isolated from Graafian follicles. The third signal, that of transferrin, while often observed in the spectra of whole ovaries, has been attributed to residual blood in the tissues examined. The effects of oxygen on these spectra has been found to be considerable and is discussed.

Carbonato-bridged Ni(II)2Ln(III)2 (Ln(III) = Gd(III), Tb(III), Dy(III)) complexes generated by atmospheric CO2 fixation and their single-molecule-magnet behavior: [(μ4-CO3)2{Ni(II)(3-MeOsaltn)(MeOH or H2O)Ln(III)(NO3)}2]·solvent [3-MeOsaltn = N,N'-bis(3-methoxy-2-oxybenzylidene)-1,3-propanediaminato].

PubMed

Sakamoto, Soichiro; Fujinami, Takeshi; Nishi, Koshiro; Matsumoto, Naohide; Mochida, Naotaka; Ishida, Takayuki; Sunatsuki, Yukinari; Re, Nazzareno

2013-06-17

Atmospheric CO2 fixation of [Ni(II)(3-MeOsaltn)(H2O)2]·2.5H2O [3-MeOsaltn = N,N'-bis(3-methoxy-2-oxybenzylidene)-1,3-propanediaminato], Ln(III)(NO3)3·6H2O, and triethylamine occurred in methanol/acetone, giving a first series of carbonato-bridged Ni(II)2Ln(III)2 complexes [(μ4-CO3)2{Ni(II)(3-MeOsaltn)(MeOH)Ln(III)(NO3)}2] (1Gd, 1Tb, and 1Dy). When the reaction was carried out in acetonitrile/water, it gave a second series of complexes [(μ4-CO3)2{Ni(II)(3-MeOsaltn)(H2O)Ln(III)(NO3)}2]·2CH3CN·2H2O (2Gd, 2Tb, and 2Dy). For both series, each Ni(II)2Ln(III)2 structure can be described as two di-μ-phenoxo-bridged Ni(II)Ln(III) binuclear units bridged by two carbonato CO3(2-) units to form a carbonato-bridged (μ4-CO3)2{Ni(II)2Ln(III)2} structure. The high-spin Ni(II) ion has octahedral coordination geometry, and the Ln(III) ion is coordinated by O9 donor atoms from Ni(II)(3-MeOsaltn), bidentate NO3(-), and one and two oxygen atoms of two CO3(2-) ions. The NO3(-) ion for the first series roughly lie on Ln-O(methoxy) bonds and are tilted toward the outside, while for the second series, the two oxygen atoms roughly lie on one of the Ln-O(phenoxy) bonds due to the intramolecular hydrogen bond. The temperature-dependent magnetic susceptibilities indicated a ferromagnetic interaction between the Ni(II) and Ln(III) ions (Ln(III) = Gd(III), Tb(III), Dy(III)) for all of the complexes, with a distinctly different magnetic behavior between the two series in the lowest-temperature region due to the Ln(III)-Ln(III) magnetic interaction and/or different magnetic anisotropies of the Tb(III) or Dy(III) ion. Alternating-current susceptibility measurements under the 0 and 1000 Oe direct-current (dc) bias fields showed no magnetic relaxation for the Ni(II)2Gd(III)2 complexes but exhibited an out-of-phase signal for Ni(II)2Tb(III)2 and Ni(II)2Dy(III)2, indicative of slow relaxation of magnetization. The energy barriers, Δ/kB, for the spin flipping were estimated from the Arrhenius

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). Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Structure and magnetism of a Mn(III)-Mn(II)-Mn(II)-Mn(III) chain complex.

PubMed

Uhrecký, Róbert; Moncoľ, Ján; Koman, Marian; Titiš, Ján; Boča, Roman

2013-07-14

A novel tetranuclear manganese(II/III) complex with anions of pyridine-2,6-dicarboxylic acid (dipicolinic acid) has been synthesised and magneto-structurally characterised. The crystal structure of [Mn(II)2Mn(III)2(dipic)6(H2O)4]·2CH3OH·4H2O has been determined by single-crystal X-ray diffraction. The tetranuclear complex molecule [Mn(II)2Mn(III)2(dipic)6(H2O)4] is centrosymmetric and two manganese(II) and two manganese(III) atoms are bridged by four dipicolinate ligands. The complex molecules and uncoordinated water and methanol molecules are connected through hydrogen bonds and they form a 3D supramolecular hydrogen-bonding network.

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.

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.

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…

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…

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…

The genetic basis of natural variation for iron homeostasis in the maize IBM population

PubMed Central

2014-01-01

Background Iron (Fe) deficiency symptoms in maize (Zea mays subsp. mays) express as leaf chlorosis, growth retardation, as well as yield reduction and are typically observed when plants grow in calcareous soils at alkaline pH. To improve our understanding of genotypical variability in the tolerance to Fe deficiency-induced chlorosis, the objectives of this study were to (i) determine the natural genetic variation of traits related to Fe homeostasis in the maize intermated B73 × Mo17 (IBM) population, (ii) to identify quantitative trait loci (QTLs) for these traits, and (iii) to analyze expression levels of genes known to be involved in Fe homeostasis as well as of candidate genes obtained from the QTL analysis. Results In hydroponically-grown maize, a total of 47 and 39 QTLs were detected for the traits recorded under limited and adequate supply of Fe, respectively. Conclusions From the QTL results, we were able to identify new putative candidate genes involved in Fe homeostasis under a deficient or adequate Fe nutritional status, like Ferredoxin class gene, putative ferredoxin PETF, metal tolerance protein MTP4, and MTP8. Furthermore, our expression analysis of candidate genes suggested the importance of trans-acting regulation for 2’-deoxymugineic acid synthase 1 (DMAS1), nicotianamine synthase (NAS3, NAS1), formate dehydrogenase 1 (FDH1), methylthioribose-1-phosphate isomerase (IDI2), aspartate/tyrosine/aromatic aminotransferase (IDI4), and methylthioribose kinase (MTK). PMID:24400634

Antisense inhibition of apoB synthesis with mipomersen reduces plasma apoC-III and apoC-III-containing lipoproteins.

PubMed

Furtado, Jeremy D; Wedel, Mark K; Sacks, Frank M

2012-04-01

Mipomersen, an antisense oligonucleotide that reduces hepatic production of apoB, has been shown in phase 2 studies to decrease plasma apoB, LDL cholesterol (LDL-C), and triglycerides. ApoC-III inhibits VLDL and LDL clearance, and it stimulates inflammatory responses in vascular cells. Concentrations of VLDL or LDL with apoC-III independently predict cardiovascular disease. We performed an exploratory posthoc analysis on a subset of hypercholesterolemic subjects obtained from a randomized controlled dose-ranging phase 2 study of mipomersen receiving 100, 200, or 300 mg/wk, or placebo for 13 wk (n = 8 each). ApoC-III-containing lipoproteins were isolated by immuno-affinity chromatography and ultracentrifugation. Mipomersen 200 and 300 mg/wk reduced total apoC-III from baseline by 6 mg/dl (38-42%) compared with placebo group (P < 0.01), and it reduced apoC-III in both apoB lipoproteins and HDL. Mipomersen 100, 200, and 300 mg doses reduced apoB concentration of LDL with apoC-III (27%, 38%, and 46%; P < 0.05). Mipomersen reduced apoC-III concentration in HDL. The drug had no effect on apoE concentration in total plasma and in apoB lipoproteins. In summary, antisense inhibition of apoB synthesis reduced plasma concentrations of apoC-III and apoC-III-containing lipoproteins. Lower concentrations of apoC-III and LDL with apoC-III are associated with reduced risk of coronary heart disease (CHD) in epidemiologic studies independent of traditional risk factors.

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.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peng, Ying; Xu, Feng, E-mail: xuf@xtal.tsinghua.edu.cn; Bell, Stephen G.

Palustrisredoxin reductase (RPA3782, PuR), a flavin-dependent ferredoxin reductase, is an essential component of the Class I cytochrome P450 systems in Rhodopseudomonas palustris CGA009. Crystals of PuR that diffract to 2.2 Å resolution have been obtained. Palustrisredoxin reductase from Rhodopseudomonas palustris CGA009, a member of the oxygenase-coupled NADH-dependent ferredoxin reductase (ONFR) family, catalyzes electron transfer from NADH to ferredoxins. It is an essential component of the cytochrome P450 systems in R. palustris CGA009, a model organism with diverse metabolic pathways. Here, the crystallization of palustrisredoxin reductase is reported. The crystals belong to the trigonal space group P3{sub 2}21, with unit-cell parametersmore » a = 107.5, b = 107.5, c = 69.9 Å, and diffract to 2.2 Å resolution on a synchrotron source.« less

A view from Cheyenne Mountain: Generation III's perspective of Keystone III.

PubMed

Bliss, Erika; Cadwallader, Kara; Steyer, Terrence E; Clements, Deborah S; Devoe, Jennifer E; Fink, Kenneth; Khubesrian, Marina; Lyons, Paul; Steiner, Elizabeth; Weismiller, David

2014-01-01

In October 2000 the family of family medicine convened the Keystone III conference at Cheyenne Mountain Resort. Keystone III participants included members of Generation I (entered practice before 1970), Generation II (entered 1970-1990), and Generation III (entered after 1990). They represented a wide range of family physicians, from medical students to founders of the discipline, and from small-town solo practice to academic medicine. During the conference, the three generations worked together and separately thinking about the past, present, and future of family medicine, our roles in it, and how the understanding of a family physician and our discipline had and would continue to evolve. After the conference, the 10 Generation III members wrote the article published here, reflecting on our experiences as new physicians and physicians in training, and the similarities and differences between our experiences and those of physicians in Generations I and II. Key similarities included commitment to whole-person care, to a wide scope of practice, to community health, and to ongoing engagement with our discipline. Key differences included our understanding of availability, the need for work-life balance, the role of technology in the physician-patient relationship, and the perceptions of the relationship between medicine and a range of outside forces such as insurance and government. This article, presented with only minor edits, thus reflects accurately our perceptions in late 2000. The accompanying editorial reflects our current perspective.

Targeting EGFRvIII for glioblastoma multiforme.

PubMed

Yang, Ju; Yan, Jing; Liu, Baorui

2017-09-10

Glioblastoma multiforme (GBM) is the most progressive primary brain tumor. Targeting a novel and highly specific tumor antigen is one of the strategies to overcome tumors. EGFR variant III (EGFRvIII) is present in 25%-33% of all patients with GBM and is exclusively expressed on tumor tissue cells. Currently, there are various approaches to target EGFRvIII, including CAR T-cell therapy, therapeutic vaccines, antibodies, and Bi-specific T Cell Engager. In this review, we focus on the preclinical and clinical findings of targeting EGFRvIII for GBM. Copyright © 2017 Elsevier B.V. All rights reserved.

Frameshift Suppression in SACCHAROMYCES CEREVISIAE. III. Isolation and Genetic Properties of Group III Suppressors

PubMed Central

Cummins, Claudia M.; Gaber, Richard F.; Culbertson, Michael R.; Mann, Richard; Fink, Gerald R.

1980-01-01

Suppressors of ICR-induced mutations that exhibit behavior similar to bacterial frameshift suppressors have been identified in the yeast Saccharomyces cerevisiae. The yeast suppressors have been divided into two groups. Previous evidence indicated that suppressors of one group (Group II: SUF1, SUF3, SUF4, SUF5 and SUF6) represent mutations in the structural genes for glycyl-tRNA's. Suppressors of the other group (Group III: SUF2 and SUF7) were less well characterized. Although they suppressed some ICR-revertible mutations, they failed to suppress Group II frameshift mutations. This communication provides a more thorough characterization of the Group III suppressors and describes the isolation and properties of four new suppressors in that group (SUF8, SUF9, SUF10 and suf11).——In our original study, Group III suppressors were isolated as revertants of the Group III mutations his4–712 and his4–713. All suppressors obtained as ICR-induced revertants of these mutations mapped at the SUF2 locus near the centromere of chromosome III. Suppressors mapping at other loci were obtained in this study by analyzing spontaneous and UV-induced revertants of the Group III mutations. SUF2 and SUF10 suppress both Group III his4 mutations, whereas SUF7, SUF8, SUF9 and suf11 suppress his4–713, but not his4–712. All of the suppressors except suf11 are dominant in diploids homozygous for his4-713. The suppressors fail to suppress representative UAA, UAG and UGA nonsense mutations.——SUF9 is linked to the centromere of chromosome VI, and SUF10 is linked to the centromere of chromosome XIV. A triploid mapping procedure was used to determine the chromosome locations of SUF7 and SUF8. Subsequent standard crosses revealed linkage of SUF7 to cdc5 on chromosome XIII and linkage of SUF8 to cdc12 and pet3 on chromosome VIII. PMID:7009319

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.

Oxidative mutagenesis of doxorubicin-Fe(III) complex.

PubMed

Kostoryz, E L; Yourtee, D M

2001-02-20

Doxorubicin has a high affinity for inorganic iron, Fe(III), and has potential to form doxorubicin-Fe(III) complexes in biological systems. Indirect involvement of iron has been substantiated in the oxidative mutagenicity of doxorubicin. In this study, however, direct involvement of Fe(III) was evaluated in mutagenicity studies with the doxorubicin-Fe(III) complex. The Salmonella mutagenicity assay with strain TA102 was used with a pre-incubation step. The highest mutagenicity of doxorubicin-Fe(III) complex was observed at the dose of 2.5nmol/plate of the complex. The S9-mix decreased this highest mutagenicity but increased the number of revertants at a higher dose of 10nmol/plate of the complex. On the other hand, the mutagenicity of the doxorubicin-Fe(III) complex at the doses of 0.25, 0.5, 1 and 2nmol/plate was enhanced about twice by the addition of glutathione plus H(2)O(2). This enhanced mutagenicity as well as of the complex itself, the complex plus glutathione, and the complex plus H(2)O(2) were reduced by the addition of ADR-529, an Fe(III) chelator, and potassium iodide, a hydroxyl radical scavenger. These results indicate that doxorubicin-Fe(III) complex exert the mutagenicity through oxidative DNA damage and that Fe(III) is a required element in the mutagenesis of doxorubicin.

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

PubMed

Liu, Hongyan; Wang, Hongyu

2016-07-01

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

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 �

9,10-phenanthrenesemiquinone radical complexes of ruthenium(III), osmium(III) and rhodium(III) and redox series.

PubMed

Biswas, Manas Kumar; Patra, Sarat Chandra; Maity, Amarendra Nath; Ke, Shyue-Chu; Weyhermüller, Thomas; Ghosh, Prasanta

2013-05-14

Reactions of 9,10-phenanthrenequinone (PQ) in toluene with [M(II)(PPh3)3X2] at 298 K afford green complexes, trans-[M(PQ)(PPh3)2X2] (M = Ru, X = Cl, 1; M = Os, X = Br, 2) in moderate yields. Reaction of anhydrous RhCl3 with PQ and PPh3 in boiling ethanol affords the dark brown paramagnetic complex, cis-[Rh(PQ)(PPh3)2Cl2] (3) in good yields. Diffusion of iodine solution in n-hexane to the trans-[Os(PQ) (PPh3)2(CO)(Br)] solution in CH2Cl2 generates the crystals of trans-[Os(PQ)(PPh3)2(CO)(Br)](+)I3(-), (4(+))I3(-)), in lower yields. Single crystal X-ray structure determinations of 1·2toluene, 2·CH2Cl2 and 4(+)I3(-), UV-vis/NIR absorption spectra, EPR spectra of 3, electrochemical activities and DFT calculations on 1, 2, trans-[Ru(PQ)(PMe3)2Cl2] (1Me), trans-[Os(PQ)(PMe3)2Br2] (2Me), cis-[Rh(PQ)(PMe3)2Cl2] (3Me) and their oxidized and reduced analogues including trans-[Os(PQ)(PMe3)2(CO)(Br)](+) (4Me(+)) substantiated that 1-3 are the 9,10-phenanthrenesemiquinone radical (PQ(˙-)) complexes of ruthenium(III), osmium(III) and rhodium(III) and are defined as trans/cis-[M(III)(PQ(˙-))(PPh3)2X2] with a minor contribution of the resonance form trans/cis-[M(II)(PQ)(PPh3)2X2]. Two comparatively longer C-O (1.286(4) Å) and the shorter C-C lengths (1.415(7) Å) of the OO-chelate of 1·2toluene and 2·CH2Cl2 and the isotropic fluid solution EPR signal at g = 1.999 of 3 are consistent with the existence of the reduced PQ(˙-) ligand in 1-3 complexes. Anisotropic EPR spectra of the frozen glasses (g11 = g22 = 2.0046 and g33 = 1.9874) and solids (g11 = g22 = 2.005 and g33 = 1.987) instigate the contribution of the resonance form, cis-[Rh(II)(PQ)(PPh3)2Cl2] in 3. DFT calculations established that the closed shell singlet (CSS) solutions of 1Me and 2Me are unstable due to open shell singlet (OSS) perturbation. However, the broken symmetry (BS) (1,1) Ms = 0 solutions of 1Me and 2Me are respectively 22.6 and 24.2 kJ mole(-1) lower in energy and reproduced the experimental bond

Sensitizing Tb(III) and Eu(III) emission with triarylboron functionalized 1,3-diketonato ligands.

PubMed

Smith, Larissa F; Blight, Barry A; Park, Hee-Jun; Wang, Suning

2014-08-04

Four BMes2Ar (Mes = mesityl, Ar = phenyl or duryl) functionalized 1,3-diketonato ligands have been investigated for use in selective sensitization of Tb(III) and Eu(III) emission. These ligands have the general formula of [R1C(O)CR2C(O)R3](-) (R1 = Ph, R2 = H, R3 = p-Ph-BMes2, L1; R1 = R3 = p-Ph-BMes2, R2 = H, L2; R1 = R3 = Me, R2 = p-Ph-BMes2, L3; R1 = R3 = Me, R2 = p-duryl-BMes2, L4) and belong to class I (L1 and L2) and class II (L3 and L4), respectively. In class I, the boron unit is conjugated with the phenyl linker and the diketone backbone, while in class II, the boron unit, the linker unit, and the diketone unit are nonconjugated with a mutually orthogonal arrangement. To understand the impact of the location of the BMes2Ar unit on the electronic properties of the 1,3-diketone molecules and their ability in activating lanthanide emission, the difluoroboron chelate compounds (1-BF2 to 4-BF2) of ligands L1-L4 were synthesized and examined. The class I ligands were effective in activating Eu(III) emission, while the class II ligands were effective in activating Tb(III) emission. Four Ln(III) complexes, 1Eu, 2Eu, 3Tb, and 4Tb, based on the L1-L4 ligands, respectively, were prepared and examined. The emission quantum efficiency of 1Eu and 2Eu is low (Φ(Eu) ≤ 0.01 in THF, 0.07-0.13 in the solid state), but can be greatly enhanced by the addition of fluoride ions. In contrast, the complex 4Tb has a moderate emission efficiency (Φ(Tb) = 0.14 in THF, 0.47 in the solid state) and experiences a distinct emission quenching upon the addition of fluoride. The selective sensitization of Eu(III) and Tb(III) by L1-L4 and the distinct luminescent response of their Ln(III) complexes toward fluoride ions are caused by the distinct intraligand charge transfer transitions of the two different classes of ligands involving the BMes2 unit.

Epidermal Growth Factor Receptor Variant III (EGFRvIII) Positivity in EGFR-Amplified Glioblastomas: Prognostic Role and Comparison between Primary and Recurrent Tumors.

PubMed

Felsberg, Jörg; Hentschel, Bettina; Kaulich, Kerstin; Gramatzki, Dorothee; Zacher, Angela; Malzkorn, Bastian; Kamp, Marcel; Sabel, Michael; Simon, Matthias; Westphal, Manfred; Schackert, Gabriele; Tonn, Jörg C; Pietsch, Torsten; von Deimling, Andreas; Loeffler, Markus; Reifenberger, Guido; Weller, Michael

2017-11-15

Purpose: Approximately 40% of all glioblastomas have amplified the EGFR gene, and about half of these tumors express the EGFRvIII variant. The prognostic role of EGFRvIII in EGFR -amplified glioblastoma patients and changes in EGFRvIII expression in recurrent versus primary glioblastomas remain controversial, but such data are highly relevant for EGFRvIII-targeted therapies. Experimental Design: EGFR -amplified glioblastomas from 106 patients were assessed for EGFRvIII positivity. Changes in EGFR amplification and EGFRvIII status from primary to recurrent glioblastomas were evaluated in 40 patients with EGFR -amplified tumors and 33 patients with EGFR -nonamplified tumors. EGFR single-nucleotide variants (SNV) were assessed in 27 patients. Data were correlated with outcome and validated in 150 glioblastoma patients from The Cancer Genome Atlas (TCGA) consortium. Results: Sixty of 106 EGFR -amplified glioblastomas were EGFRvIII-positive (56.6%). EGFRvIII positivity was not associated with different progression-free or overall survival. EGFRvIII status was unchanged at recurrence in 35 of 40 patients with EGFR -amplified primary tumors (87.5%). Four patients lost and one patient gained EGFRvIII positivity at recurrence. None of 33 EGFR- nonamplified glioblastomas acquired EGFR amplification or EGFRvIII at recurrence. EGFR SNVs were frequent in EGFR -amplified tumors, but were not linked to survival. Conclusions: EGFRvIII and EGFR SNVs are not prognostic in EGFR -amplified glioblastoma patients. EGFR amplification is retained in recurrent glioblastomas. Most EGFRvIII-positive glioblastomas maintain EGFRvIII positivity at recurrence. However, EGFRvIII expression may change in a subset of patients at recurrence, thus repeated biopsy with reassessment of EGFRvIII status is recommended for patients with recurrent glioblastoma to receive EGFRvIII-targeting agents. Clin Cancer Res; 23(22); 6846-55. ©2017 AACR . ©2017 American Association for Cancer Research.

Solution 1H NMR determination of secondary structure for the three-iron form of ferredoxin from the hyperthermophilic archaeon Pyrococcus furiosus.

PubMed

Teng, Q; Zhou, Z H; Smith, E T; Busse, S C; Howard, J B; Adams, M W; La Mar, G N

1994-05-24

Two-dimensional 1H NMR data have been used to make sequence-specific assignments and define the secondary structure of the three-iron form of the oxidized ferredoxin, Fd, from the hyperthermophilic archaeon Pyrococcus furiosus, Pf. Signals for at least some protons were located for 65 of the 66 amino acids in the sequence, in spite of the paramagnetic (S = 1/2) ground state, but not all could be assigned. Unassigned and missing signals could be qualitatively correlated with the expected proximity of the protons to the paramagnetic cluster. The secondary structure was deduced from qualitative analysis of the 2D nuclear Overhauser effect, which identified two antiparallel beta-sheets, one triple-stranded including Ala1-Ser5, Val39-Glu41, and Thr62-Ala66, and one double-stranded consisting of Glu26-Asn28 and Lys32-Glu34, as well as an alpha-helix involving Glu43-Glu54. Three tight type I turns are located at residues Asp7-Thr10, Pro22-Phe25, and Asp29-Gly31. Comparison with the crystal structure of Desulfovibrio gigas, Dg, Fd (Kissinger et al., 1991) reveals a very similar folding topology, although several secondary structural elements are extended in Pf relative to Dg Fd. Thus the beta-sheet involving the two termini is expanded to include the two terminal residues and incorporates a third strand from the internal loop that is lengthened by several insertions in Pf relative to Dg Fd. The double-stranded beta-sheet in the interior of Pf Fd is lengthened slightly due to a much tighter type I turn between the two strands. The helix near the C-terminus is three residues longer in Pf than in Dg Fd, as well as being shifted toward the N-terminus. The disulfide link between the two nonligating Cys residues (Cys21 and Cys48) is conserved in Pf Fd, but the link near the C-terminus is in the middle of the long alpha-helix in Pf Fd, instead of at the N-terminus of the helix as in Dg Fd. The extensions of the beta-sheets and alpha-helix increase the number of main

Unsymmetrical Bimetallic Complexes with MII–(μ-OH)–MII Cores (MIIMIII = FeIIFeIII, MnIIFeIII, MnIIMnIII): Structural, Magnetic, and Redox Properties

PubMed Central

Sano, Yohei; Weitz, Andrew C.; Ziller, Joseph W.; Hendrich, Michael P.; Borovik, A.S.

2013-01-01

Heterobimetallic cores are important unit within the active sites of metalloproteins, but are often difficult to duplicate in synthetic systems. We have developed a synthetic approach for the preparation of a complex with a MnII–(μ-OH)–FeIII core, in which the metal centers have different coordination environments. Structural and physical data support the assignment of this complex as a heterobimetallic system. Comparison with the analogous homobimetallic complexes, those containing MnII–(μ-OH)–MnIII and FeII–(μ-OH)–FeIII cores, further supports this assignment. PMID:23992041

Thermodynamic model for solution behavior and solid-liquid equilibrium in Na-Al(III)-Fe(III)-Cr(III)-Cl-H2O system at 25°C

NASA Astrophysics Data System (ADS)

André, Laurent; Christov, Christomir; Lassin, Arnault; Azaroual, Mohamed

2018-03-01

The knowledge of the thermodynamic behavior of multicomponent aqueous electrolyte systems is of main interest in geo-, and environmental-sciences. The main objective of this study is the development of a high accuracy thermodynamic model for solution behavior, and highly soluble M(III)Cl3(s) (M= Al, Fe, Cr) minerals solubility in Na-Al(III)-Cr(III)-Fe(III)-Cl-H2O system at 25°C. Comprehensive thermodynamic models that accurately predict aluminium, chromium and iron aqueous chemistry and M(III) mineral solubilities as a function of pH, solution composition and concentration are critical for understanding many important geochemical and environmental processes involving these metals (e.g., mineral dissolution/alteration, rock formation, changes in rock permeability and fluid flow, soil formation, mass transport, toxic M(III) remediation). Such a model would also have many industrial applications (e.g., aluminium, chromium and iron production, and their corrosion, solve scaling problems in geothermal energy and oil production). Comparisons of solubility and activity calculations with the experimental data in binary and ternary systems indicate that model predictions are within the uncertainty of the data. Limitations of the model due to data insufficiencies are discussed. The solubility modeling approach, implemented to the Pitzer specific interaction equations is employed. The resulting parameterization was developed for the geochemical Pitzer formalism based PHREEQC database.

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.

Synthesis of Er(III)/Yb(III)-doped BiF3 upconversion nanoparticles for use in optical thermometry.

PubMed

Du, Peng; Yu, Jae Su

2018-03-23

The authors describe an ethylene glycol assisted precipitation method for synthesis of Er(III)/Yb(III)-doped BiF 3 nanoparticles (NPs) at room temperature. Under 980-nm light irradiation, the NPs emit upconversion (UC) emission of Er(III) ions as a result of a two-photon absorption process. The temperature-dependent green emissions (peaking at 525 and 545 nm) are used to establish an unambiguous relationship between the ratio of fluorescence intensities and temperature. The NPs have a maximum sensitivity of 6.5 × 10 -3  K -1 at 619 K and can be applied over the 291-691 K temperature range. The results indicate that these NPs are a promising candidate for optical thermometry. Graphical abstract Schematic of the room-temperature preparation of Er(III)/Yb(III)-doped BiF 3 nanoparticles with strongly temperature-dependent upconversion emission.

Simultaneous Oxidation and Sequestration of As(III) from Water by Using Redox Polymer-Based Fe(III) Oxide Nanocomposite.

PubMed

Zhang, Xiaolin; Wu, Mengfei; Dong, Hao; Li, Hongchao; Pan, Bingcai

2017-06-06

Water decontamination from As(III) is an urgent but still challenging task. Herein, we fabricated a bifunctional nanocomposite HFO@PS-Cl for highly efficient removal of As(III), with active chlorine covalently binding spherical polystyrene host for in situ oxidation of As(III) to As(V), and Fe(III) hydroxide (HFO) nanoparticles (NPs) embedded inside for specific As(V) removal. HFO@PS-Cl could work effectively in a wide pH range (5-9), and other substances like sulfate, chloride, bicarbonate, silicate, and humic acid exert insignificant effect on As(III) removal. As(III) sequestration is realized via two pathways, that is, oxidation to As(V) by the active chlorine followed by specific As(V) adsorption onto HFO NPs, and As(III) adsorption onto HFO NPs followed by oxidation to As(V). The exhausted HFO@PS-Cl could be refreshed for cyclic runs with insignificant capacity loss by the combined regeneration strategy, that is, alkaline solution to rinse the adsorbed As(V) and NaClO solution to renew the host oxidation capability. In addition, fixed-bed experiments demonstrated that the HFO@PS-Cl column could generate >1760 bed volume (BV) effluent from a synthetic As(III)-containing groundwater to meet the drinking water standard (<10 μg As/L), whereas other two HFO nanocomposites, HFO@PS-N and HFO@D201 could only generate 450 and 600 BV effluents under otherwise identical conditions.

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

Synthesis and physico-chemical studies on neodymium(III) and samarium(III) complexes with tetraaza macrocyclic ligands

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goel, S.; Pandey, U.K.; Pandey, O.P.

1988-05-01

Reactions of neodymium trichloride and samarium trichloride with 6,7,13,14-R/sub 4/ - 3,10-X/sub 2/-(14)-5,7,12,14-tetraene-1,5,8,12-N/sub 4/-(2,4,9,11-N/sub 4/) (R = CH/sub 3/, X = 0 (L/sub 1//sup (1)/); R = C/sub 6/H/sub 5/, X = O (L/sub 1//sup (2)/); R = CH/sub 3/, X = S(L/sub 2//sup (1)/)) and R = C/sub 6/H/sub 5/, X = S(/sub 2//sup (2)/)) have been studied in ethanol and complexes of the type (M(L/sub 1//sup (1)/ or L/sub 1//sup (2)/))Cl/sub 3/ and (M(L/sub 2//sup (1)/ or L/sub 2//sup (2)/)(H/sub 2/O)/sub 2/)Cl/sub 3/ (M = Nd(III) and Sm(III)) have been isolated. In addition, macrocyclic complexes of Nd(III) andmore » Sm(III) with another series of tetraaza ligands, viz, 5,6,11,12-R/sub 4/-3,8-X/sub 2/-(12)-4,6,10,12-tetraene-1,4,7,10-N/sub 4/-(2,9-N/sub 2/) (R = CH/sub 3/, X = O (L/sub 3//sup (1)/); R = C/sub 6/H/sub 5/, X = O(L/sub 3//sup (2)/); R = CH/sub 3/, X = S(L/sub 4//sup (1)/); R = C/sub 6/H/sub 5/, X = S(L/sub 4//sup (2)/)), formulated as (M(L/sub 3//sup (1)/, L/sub 3//sup (2)/, L/sub 4//sup (1)/ or L/sub 4//sup (2)/)(H/sub 2/O)/sub 2/)Cl/sub 3/ (M = Nd(III) and Sm(III)) have been prepared by template condensation of Nd(III) and Sm(III) complexes of diacetylbis(semicarbazonethiosemicarbazone) or benzilibis(semicarbazonethiosemicarbazone) with diacetyl or benzil. The complexes have been identified by elemental analysis, electrical conductance, spectral and thermal measurements.« less

UNICORN (Version III) Methodology.

DTIC Science & Technology

1976-10-01

rAD-A124 766 UNICORN CYERSION’III) NETHODOLOGYMU SCIENCE / APPLICATIONS INC ENGLEWOOD CO L M BLACKWELL ET AL. OCT 76 SAI-76-648-DEN DCAII-75-C-802...1ii4 4% 83 02 010GZ SAI-76-048-DEN .. UNICORN (VERSION III) METHODOLOGY TECHNICAL MEMORANDUM by core L. M. Blackwell . IF’l 4 H. E. Hock T. A. Kriz D...6 DISCUSSION .. ... ..... ..... ..... ..... ...... 7 FINDINGS AND CONCLUSIONS--THE UNICORN METHODOLOGY .. .. ... ..... 9

Hyper III on ramp

NASA Technical Reports Server (NTRS)

1969-01-01

The Hyper III was a full-scale lifting-body remotely piloted research vehicle (RPRV) built at what was then the NASA Flight Research Center located at Edwards Air Force Base in Southern California. The Flight Research Center (FRC--as Dryden was named from 1959 until 1976) already had experience with testing small-scale aircraft using model-airplane techniques, but the first true remotely piloted research vehicle was the Hyper III, which flew only once in December 1969. At that time, the Center was engaged in flight research with a variety of reentry shapes called lifting bodies, and there was a desire both to expand the flight research experience with maneuverable reentry vehicles, including a high-performance, variable-geometry craft, and to investigate a remotely piloted flight research technique that made maximum use of a research pilot's skill and experience by placing him 'in the loop' as if he were in the cockpit. (There have been, as yet, no female research pilots assigned to Dryden.) The Hyper III as originally conceived was a stiletto-shaped lifting body that had resulted from a study at NASA's Langley Research Center in Hampton, Virginia. It was one of a number of hypersonic, cross-range reentry vehicles studied at Langley. (Hypersonic means Mach 5--five times the speed of sound--or faster; cross-range means able to fly a considerable distance to the left or right of the initial reentry path.) The FRC added a small, deployable, skewed wing to compensate for the shape's extremely low glide ratio. Shop personnel built the 32-foot-long Hyper III and covered its tubular frame with dacron, aluminum, and fiberglass, for about $6,500. Hyper III employed the same '8-ball' attitude indicator developed for control-room use when flying the X-15, two model-airplane receivers to command the vehicle's hydraulic controls, and a telemetry system (surplus from the X-15 program) to transmit 12 channels of data to the ground not only for display and control but for data

Complexation of Curium(III) with DTPA at 10–70 °C: Comparison with Eu(III)–DTPA in Thermodynamics, Luminescence, and Coordination Modes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tian, Guoxin; Zhang, Zhiyong; Martin, Leigh R.

Separation of trivalent actinides (An(III)) from trivalent lanthanides (Ln(III)) is a challenging task because of their nearly identical chemical properties. Diethylenetriaminepentaacetate (DTPA), a key reagent used in the TALSPEAK process that effectively separates An(III) from Ln(III), is believed to play a critical role in the An(III)/Ln(III) separation. However, the underlying principles for the separation based on the difference in the complexation of DTPA with An(III) and Ln(III) remain unclear. In this work, the complexation of DTPA with Cm(III) at 10-70 ºC was investigated by spectrophotometry, luminescence spectroscopy, and microcalorimetry, in conjunction with computational methods. The binding strength, the enthalpy ofmore » complexation, the coordination modes, and the luminescence properties are compared between the Cm(III)-DTPA and Eu(III)-DTPA systems. The experimental and computational data have demonstrated that the difference between Cm(III) and Eu(III) in the binding strength with DTPA can be attributed to the stronger covalence bonding between Cm(III) and the nitrogen donors of DTPA.« less

Understanding the Mechanism of Magnetic Relaxation in Pentanuclear {MnIVMnIII2LnIII2} Single-Molecule Magnets.

PubMed

Vignesh, Kuduva R; Langley, Stuart K; Moubaraki, Boujemaa; Murray, Keith S; Rajaraman, Gopalan

2018-02-05

A new family of heterometallic pentanuclear complexes of formulas [Mn IV Mn III 2 Ln III 2 O 2 (benz) 4 (mdea) 3 (NO 3 ) 2 (MeOH)] (Ln = Dy (1-Dy), Tb (2-Tb), Gd (3-Gd), Eu (4-Eu), Sm (5-Sm), Nd (6-Nd), Pr (7-Pr); benz(H) = benzoic acid; mdeaH 2 = N-methyldiethanolamine) and [Mn IV Mn III 2 Ln III 2 O 2 (o-tol) 4 (mdea) 3 (NO 3 ) 2 (MeOH)] (Ln = Gd (8-Gd), Eu (9-Eu); o-tol(H) = o-toluic acid) have been isolated and structurally, magnetically, and theoretically characterized. dc magnetic susceptibility measurements reveal dominant antiferromagnetic magnetic interactions for each complex, except for 2-Tb and 3-Gd, which reveal an upturn in the χ M T product at low temperatures. The magnetic interactions between the spin centers in the Gd derivatives, 3-Gd and 8-Gd, which display markedly different χ M T vs T profiles, were found to be due to the interactions of the Gd III -Gd III ions which change from ferromagnetic (3-Gd) to antiferromagnetic (8-Gd) due to structural differences. ac magnetic susceptibility measurements reveal a nonzero out-of-phase component for 1-Dy and 7-Pr, but no maxima were observed above 2 K (H dc = 0 Oe), which suggests single-molecule magnet (SMM) behavior. Out-of-phase signals were observed for complexes 2-Tb, 4-Eu, 8-Gd, and 9-Eu, in the presence of a static dc field (H dc = 2000, 3000 Oe). The anisotropic nature of the lanthanide ions in the benzoate series (1-Dy, 2-Tb, 5-Sm, 6-Nd, and 7-Pr) were thoroughly investigated using ab initio methods. CASSCF calculations predict that the origin of SMM behavior in 1-Dy and 7-Pr and the applied field SMM behavior in 2-Tb does not solely originate from the single-ion anisotropy of the lanthanide ions. To fully understand the relaxation mechanism, we have employed the Lines model to fit the susceptibility data using the POLY_ANISO program, which suggests that the zero-field SMM behavior observed in complexes 1-Dy and 7-Pr is due to weak Mn III/IV -Ln III and Ln III -Ln III couplings and an

Outcome of tyrosinaemia type III.

PubMed

Ellaway, C J; Holme, E; Standing, S; Preece, M A; Green, A; Ploechl, E; Ugarte, M; Trefz, F K; Leonard, J V

2001-12-01

Tyrosinaemia type III is a rare disorder caused by a deficiency of 4-hydroxyphenylpyruvate dioxygenase, the second enzyme in the catabolic pathway of tyrosine. The majority of the nine previously reported patients have presented with neurological symptoms after the neonatal period, while others detected by neonatal screening have been asymptomatic. All have had normal liver and renal function and none has skin or eye abnormalities. A further four patients with tyrosinaemia type III are described. It is not clear whether a strict low tyrosine diet alters the natural history of tyrosinaemia type III, although there remains a suspicion that treatment may be important, at least in infancy.

Antisense inhibition of apoB synthesis with mipomersen reduces plasma apoC-III and apoC-III-containing lipoproteins

PubMed Central

Furtado, Jeremy D.; Wedel, Mark K.; Sacks, Frank M.

2012-01-01

Mipomersen, an antisense oligonucleotide that reduces hepatic production of apoB, has been shown in phase 2 studies to decrease plasma apoB, LDL cholesterol (LDL-C), and triglycerides. ApoC-III inhibits VLDL and LDL clearance, and it stimulates inflammatory responses in vascular cells. Concentrations of VLDL or LDL with apoC-III independently predict cardiovascular disease. We performed an exploratory posthoc analysis on a subset of hypercholesterolemic subjects obtained from a randomized controlled dose-ranging phase 2 study of mipomersen receiving 100, 200, or 300 mg/wk, or placebo for 13 wk (n = 8 each). ApoC-III–containing lipoproteins were isolated by immuno-affinity chromatography and ultracentrifugation. Mipomersen 200 and 300 mg/wk reduced total apoC-III from baseline by 6 mg/dl (38–42%) compared with placebo group (P < 0.01), and it reduced apoC-III in both apoB lipoproteins and HDL. Mipomersen 100, 200, and 300 mg doses reduced apoB concentration of LDL with apoC-III (27%, 38%, and 46%; P < 0.05). Mipomersen reduced apoC-III concentration in HDL. The drug had no effect on apoE concentration in total plasma and in apoB lipoproteins. In summary, antisense inhibition of apoB synthesis reduced plasma concentrations of apoC-III and apoC-III–containing lipoproteins. Lower concentrations of apoC-III and LDL with apoC-III are associated with reduced risk of coronary heart disease (CHD) in epidemiologic studies independent of traditional risk factors. PMID:22301884

TRLFS study on the complexation of Cm(III) and Eu(III) with SO3-Ph-BTBP.

PubMed

Wagner, Christoph; Müllich, Udo; Geist, Andreas; Panak, Petra J

2015-10-21

The complexation of Cm(iii) and Eu(iii) with a water soluble BTBP (sodium 3,3',3'',3'''-([2,2'-bipyridine]-6,6'-diylbis(1,2,4-triazine-3,5,6-triyl))tetrabenzenesulfonate, SO3-Ph-BTBP) is studied using time resolved laser fluorescence spectroscopy. For the complexation of Cm(iii) the influence of the medium (10(-3) M HClO4→ 0.5 M HNO3) is investigated in detail revealing important impacts of the applied medium (pH, ionic strength, anions) on the speciation and conditional stability constants. SO3-Ph-BTBP forms 1 : 2 complexes with Cm(iii) and Eu(iii). The conditional stability constants of [Cm(SO3-Ph-BTBP)2](5-) and [Eu(SO3-Ph-BTBP)2](5-) in 0.5 M HNO3 are determined to be log β02 = 7.3 ± 0.3 and log β02 = 5.4 ± 0.5, respectively. The difference of 1.9 orders of magnitude is in line with hydrophobic BT(B)P type ligands and shows that the selectivity is not affected by tuning the hydrophilicity using SO3-Ph-side chains.

Molecular structure and biological studies on Cr(III), Mn(II) and Fe(III) complexes of heterocyclic carbohydrazone ligand.

PubMed

Abu El-Reash, G M; El-Gammal, O A; Radwan, A H

2014-01-01

The chelating behavior of the ligand (H2APC) based on carbohydrazone core modified with pyridine end towards Cr(III), Mn(II) and Fe(III) ions have been examined. The (1)H NMR and IR data for H2APC revealed the presence of two stereoisomers syn and anti in both solid state and in solution in addition to the tautomeric versatility based on the flexible nature of the hydrazone linkage leading to varied coordination modes. The spectroscopic data confirmed that the ligand behaves as a monobasic tridentate in Cr(III) and Fe(III) complexes and as neutral tetradentate in Mn(II) complex. The electronic spectra as well as the magnetic measurements confirmed the octahedral geometry for all complexes. The bond length and angles were evaluated by DFT method using material studio program for all complexes. The thermal behavior and the kinetic parameters of degradation were determined using Coats-Redfern and Horowitz-Metzger methods. The antioxidant (DDPH and ABTS methods), anti-hemolytic and cytotoxic activities of the compounds have been screened. Cr(III) complex and H2APC showed the highest antioxidant activity using ABTS and DPPH methods. With respect to in vitro Ehrlich ascites assay, H2APC exhibited the potent activity followed by Fe(III) and Cr(III)complexes. Copyright © 2013 Elsevier B.V. All rights reserved.

Tetrabutylammonium Salts of Aluminum(III) and Gallium(III) Phthalocyanine Radical Anions Bonded with Fluoren-9-olato- Anions and Indium(III) Phthalocyanine Bromide Radical Anions.

PubMed

Konarev, Dmitri V; Khasanov, Salavat S; Ishikawa, Manabu; Nakano, Yoshiaki; Otsuka, Akihiro; Yamochi, Hideki; Saito, Gunzi; Lyubovskaya, Rimma N

2017-04-18

Reduction of aluminum(III), gallium(III), and indium(III) phthalocyanine chlorides by sodium fluorenone ketyl in the presence of tetrabutylammonium cations yielded crystalline salts of the type (Bu 4 N + ) 2 [M III (HFl-O - )(Pc .3- )] .- (Br - )⋅1.5 C 6 H 4 Cl 2 [M=Al (1), Ga (2); HFl-O - =fluoren-9-olato - anion; Pc=phthalocyanine] and (Bu 4 N + ) [In III Br(Pc .3- )] .- ⋅0.875 C 6 H 4 Cl 2 ⋅0.125 C 6 H 14 (3). The salts were found to contain Pc .3- radical anions with negatively charged phthalocyanine macrocycles, as evidenced by the presence of intense bands of Pc .3- in the near-IR region and a noticeable blueshift in both the Q and Soret bands of phthalocyanine. The metal(III) atoms coordinate HFl-O - anions in 1 and 2 with short Al-O and Ga-O bond lengths of 1.749(2) and 1.836(6) Å, respectively. The C-O bonds [1.402(3) and 1.391(11) Å in 1 and 2, respectively] in the HFl-O - anions are longer than the same bond in the fluorenone ketyl (1.27-1.31 Å). Salts 1-3 show effective magnetic moments of 1.72, 1.66, and 1.79 μ B at 300 K, respectively, owing to the presence of unpaired S=1/2 spins on Pc .3- . These spins are coupled antiferromagnetically with Weiss temperatures of -22, -14, and -30 K for 1-3, respectively. Coupling can occur in the corrugated two-dimensional phthalocyanine layers of 1 and 2 with an exchange interaction of J/k B =-0.9 and -1.1 K, respectively, and in the π-stacking {[In III Br(Pc .3- )] .- } 2 dimers of 3 with an exchange interaction of J/k B =-10.8 K. The salts show intense electron paramagnetic resonance (EPR) signals attributed to Pc .3- . It was found that increasing the size of the central metal atom strongly broadened these EPR signals. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hermes III

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hasti, D.E.; Ramirez, J.J.; Prestwich, K.R.

1985-01-01

Hermes III is a major new gamma-ray simulator that is part of the Simulation Technology Laboratory Project. This accelerator will significantly improve the capability of Sandia National Laboratories and the Department of Energy to evaluate the effects of gamma-ray radiation from nuclear weapons on weapons subsystems. This accelerator will be designed to produce 10/sup 5/R, 5 x 10/sup 12/ R/S and 2 x 10/sup 20/ R/S/sup 2/ over a 500 cm/sup 2/ area. The radiation dose will vary less than a factor of two over this area and less than a factor of four throughout a volume found by extendingmore » this surface 15 cm further from the gamma-ray converter. The minimum dose in this volume will be greater than or equal to5 x 10/sup 4/ R. The accelerator will be designed with sufficient reliability and short enough turn-around time to produce more than 600 radiation pulses per year. In Hermes III we are increasing the peak power in the beam from 1.2 TW of Hermes II to 16 TW. Two techniques for achieving these high powers have been successfully developed. The first technique is a high current linear induction accelerator with several parallel beams. Experiments to evaluate this concept were done on the MABE accelerator. The second concept uses induction cavities and a magnetically insulated transmission line (MITL) to form a multi-terawatt voltage adder. This report gives a detailed description of Hermes III and its components.« less

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.

Jack R. Ferrell III | NREL

Science.gov Websites

Jack R. Ferrell III Photo of Jack R. Ferrell III Jack Ferrell Research Engineer Jack.Ferrell @nrel.gov | 303-384-7777 Orcid ID http://orcid.org/0000-0003-3041-8742 Research Interests Jack Ferrell works in the Thermochemical Catalysis Research and Development (R&D) group and manages tasks on

Mechanisms for chelator stimulation of microbial Fe(III) -oxide reduction

USGS Publications Warehouse

Lovley, D.R.; Woodward, J.C.

1996-01-01

The mechanisms by which nitrilotriacetic acid (NTA) stimulated Fe(III) reduction in sediments from a petroleum-contaminated aquifer were investigated in order to gain insight into how added Fe(III) chelators stimulate the activity of hydrocarbon-degrading, Fe(III)-reducing microorganisms in these sediments, and how naturally occurring Fe(III) chelators might promote Fe(III) reduction in aquatic sediments. NTA solubilized Fe(III) from the aquifer sediments. NTA stimulation of microbial Fe(III) reduction did not appear to be the result of making calcium, magnesium, potassium, or trace metals more available to the microorganisms. Stimulation of Fe(III) reduction could not be attributed to NTA serving as a source of carbon or fixed nitrogen for Fe(III)-reducing bacteria as NTA was not degraded in the sediments. Studies with the Fe(III)-reducing microorganism, Geobacter metallireducens, and pure Fe(III)-oxide forms, demonstrated that NTA stimulated the reduction of a variety of Fe(III) forms, including highly crystalline Fe(III)-oxides such as goethite and hematite. The results suggest that NTA solubilization of insoluble Fe(III)-oxide is an important mechanism for the stimulation of Fe(III) reduction by NTA in aquifer sediments.

An appraisal of the DSM-III system.

PubMed

Adamson, J

1989-05-01

DSM-III is a major document in the history of psychiatry. The DSM-III system is here seen as an instrument that promotes the scientific development of psychiatry and the clarity of communication among psychiatrists. However a major theme of this review is that reliability does not ensure validity. While making this point it is recognized that the major defects in the DSM-III system result from scientific inadequacies inherent in present day psychiatry. This review also may be taken as an amplification of the statement in DSM-III-R that it is not a textbook. In particular the data required to arrive at diagnoses in the DSM-III system do not provide sufficient information to arrive at a comprehensive biopsychosocial case formulation, a shortcoming that has relevance for teaching and clinical practice.

Environmentally-relevant concentrations of Al(III) and Fe(III) cations induce aggregation of free DNA by complexation with phosphate group.

PubMed

Qin, Chao; Kang, Fuxing; Zhang, Wei; Shou, Weijun; Hu, Xiaojie; Gao, Yanzheng

2017-10-15

Environmental persistence of free DNA is influenced by its complexation with other chemical species and its aggregation mechanisms. However, it is not well-known how naturally-abundant metal ions, e.g., Al(III) and Fe(III), influence DNA aggregation. This study investigated aggregation behaviors of model DNA from salmon testes as influenced by metal cations, and elucidated the predominant mechanism responsible for DNA aggregation. Compared to monovalent (K + and Na + ) and divalent (Ca 2+ and Mg 2+ ) cations, Al(III) and Fe(III) species in aqueous solution caused rapid DNA aggregations. The maximal DNA aggregation occurred at 0.05 mmol/L Al(III) or 0.075 mmol/L Fe(III), respectively. A combination of atomic force microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy revealed that Al(III) and Fe(III) complexed with negatively charged phosphate groups to neutralize DNA charges, resulting in decreased electrostatic repulsion and subsequent DNA aggregation. Zeta potential measurements and molecular computation further support this mechanism. Furthermore, DNA aggregation was enhanced at higher temperature and near neutral pH. Therefore, DNA aggregation is collectively determined by many environmental factors such as ion species, temperature, and solution pH. Copyright © 2017 Elsevier Ltd. All rights reserved.

Dissimilatory Fe(III) and Mn(IV) reduction.

PubMed Central

Lovley, D R

1991-01-01

The oxidation of organic matter coupled to the reduction of Fe(III) or Mn(IV) is one of the most important biogeochemical reactions in aquatic sediments, soils, and groundwater. This process, which may have been the first globally significant mechanism for the oxidation of organic matter to carbon dioxide, plays an important role in the oxidation of natural and contaminant organic compounds in a variety of environments and contributes to other phenomena of widespread significance such as the release of metals and nutrients into water supplies, the magnetization of sediments, and the corrosion of metal. Until recently, much of the Fe(III) and Mn(IV) reduction in sedimentary environments was considered to be the result of nonenzymatic processes. However, microorganisms which can effectively couple the oxidation of organic compounds to the reduction of Fe(III) or Mn(IV) have recently been discovered. With Fe(III) or Mn(IV) as the sole electron acceptor, these organisms can completely oxidize fatty acids, hydrogen, or a variety of monoaromatic compounds. This metabolism provides energy to support growth. Sugars and amino acids can be completely oxidized by the cooperative activity of fermentative microorganisms and hydrogen- and fatty-acid-oxidizing Fe(III) and Mn(IV) reducers. This provides a microbial mechanism for the oxidation of the complex assemblage of sedimentary organic matter in Fe(III)- or Mn(IV)-reducing environments. The available evidence indicates that this enzymatic reduction of Fe(III) or Mn(IV) accounts for most of the oxidation of organic matter coupled to reduction of Fe(III) and Mn(IV) in sedimentary environments. Little is known about the diversity and ecology of the microorganisms responsible for Fe(III) and Mn(IV) reduction, and only preliminary studies have been conducted on the physiology and biochemistry of this process. PMID:1886521

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…

Analysis of gold(I/III)-complexes by HPLC-ICP-MS demonstrates gold(III) stability in surface waters.

PubMed

Ta, Christine; Reith, Frank; Brugger, Joël; Pring, Allan; Lenehan, Claire E

2014-05-20

Understanding the form in which gold is transported in surface- and groundwaters underpins our understanding of gold dispersion and (bio)geochemical cycling. Yet, to date, there are no direct techniques capable of identifying the oxidation state and complexation of gold in natural waters. We present a reversed phase ion-pairing HPLC-ICP-MS method for the separation and determination of aqueous gold(III)-chloro-hydroxyl, gold(III)-bromo-hydroxyl, gold(I)-thiosulfate, and gold(I)-cyanide complexes. Detection limits for the gold species range from 0.05 to 0.30 μg L(-1). The [Au(CN)2](-) gold cyanide complex was detected in five of six waters from tailings and adjacent monitoring bores of working gold mines. Contrary to thermodynamic predictions, evidence was obtained for the existence of Au(III)-complexes in circumneutral, hypersaline waters of a natural lake overlying a gold deposit in Western Australia. This first direct evidence for the existence and stability of Au(III)-complexes in natural surface waters suggests that Au(III)-complexes may be important for the transport and biogeochemical cycling of gold in surface environments. Overall, these results show that near-μg L(-1) enrichments of Au in environmental waters result from metastable ligands (e.g., CN(-)) as well as kinetically controlled redox processes leading to the stability of highly soluble Au(III)-complexes.

Complexation of Nd(III) with tetraborate ion and its effect on actinide (III) solubility in WIPP brine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Borkowski, Marian; Richmann, Michael K; Reed, Donald T

2010-01-01

The potential importance of tetraborate complexation on lanthanide(III) and actinide(III) solubility is recognized in the literature but a systematic study of f-element complexation has not been performed. In neodymium solubility studies in WIPP brines, the carbonate complexation effect is not observed since tetraborate ions form a moderately strong complex with neodymium(III). The existence of these tetraborate complexes was established for low and high ionic strength solutions. Changes in neodymium(III) concentrations in undersaturation experiments were used to determine the neodymium with tetraborate stability constants as a function of NaCl ionic strength. As very low Nd(III) concentrations have to be measured, itmore » was necessary to use an extraction pre-concentration step combined with ICP-MS analysis to extend the detection limit by a factor of 50. The determined Nd(III) with borate stability constants at infinite dilution and 25 C are equal to log {beta}{sub 1} = 4.55 {+-} 0.06 using the SIT approach, equal to log {beta}{sub 1} = 4.99 {+-} 0.30 using the Pitzer approach, with an apparent log {beta}{sub 1} = 4.06 {+-} 0.15 (in molal units) at I = 5.6 m NaCl. Pitzer ion-interaction parameters for neodymium with tetraborate and SIT interaction coefficients were also determined and reported.« less

Impact of Fe(III)-OM complexes and Fe(III) polymerization on SOM pools reactivity under different land uses

NASA Astrophysics Data System (ADS)

Giannetta, B.; Plaza, C.; Zaccone, C.; Siebecker, M. G.; Rovira, P.; Vischetti, C.; Sparks, D. L.

2017-12-01

Soil organic matter (SOM) protection and long-term accumulation are controlled by adsorption to mineral surfaces in different ways, depending on its molecular structure and pedo-climatic conditions. Iron (Fe) oxides are known to be key regulators of the soil carbon (C) cycle, and Fe speciation in soils is highly dependent on environmental conditions and chemical interactions with SOM. However, the molecular structure and hydrolysis of Fe species formed in association with SOM is still poorly described. We hypothesize the existence of two pools of Fe which interact with SOM: mononuclear Fe(III)-SOM complexes and precipitated Fe(III) hydroxides. To verify our hypothesis, we investigated the interactions between Fe(III) and physically isolated soil fractions by means of batch experiments at pH 7. Specifically, we examined the fine silt plus clay (FSi+C) fraction, obtained by ultrasonic dispersion and wet sieving. The soil samples spanned several land uses, including coniferous forest (CFS), grassland (GS), technosols (TS) and agricultural (AS) soils. Solid phase products and supernatants were analyzed for C and Fe content. X-ray diffraction (XRD) and Brunauer-Emmett-Teller (BET) analysis were also performed. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) was used to assess the main C functional groups involved in C complexation and desorption experiments. Preliminary linear combination fitting (LCF) of Fe K-edge extended X-ray absorption fine structure (EXAFS) spectra suggested the formation of ferrihydrite-like polymeric Fe(III) oxides in reacted CFS and GS samples, with higher C and Fe concentration. Conversely, mononuclear Fe(III) OM complexes dominated the speciation for TS and AS samples, characterized by lower C and Fe concentration, inhibiting the hydrolysis and polymerization of Fe (III). This approach will help revealing the mechanisms by which SOM pools can control Fe(III) speciation, and will elucidate how both Fe(III

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.…

Comparison of psychosocial status in treatment-seeking women with class III vs. class I-II obesity.

PubMed

Wadden, Thomas A; Butryn, Meghan L; Sarwer, David B; Fabricatore, Anthony N; Crerand, Canice E; Lipschutz, Patti E; Faulconbridge, Lucy; Raper, Steven; Williams, Noel N

2006-01-01

This study compared the psychosocial status and weight loss expectations of women with extreme (class III) obesity who sought bariatric surgery with those of women with class I-II obesity who enrolled in a research study on behavioral weight control. Before treatment, all participants completed the Beck Depression Inventory-II and the Weight and Lifestyle Inventory. This latter questionnaire assesses several domains including symptoms of depression and low self-esteem, history of psychiatric complications, current stressors, and weight loss expectations. Women with class III obesity, as compared with class I-II, reported significantly more symptoms of depression. Fully 25% of women in the former group appeared to have a significant mood disorder that would benefit from treatment. As compared with women with class I-II obesity, significantly more women with class III obesity also reported a history of psychiatric complications, which included physical and sexual abuse and greater stress related to their physical health and financial/legal matters. Both groups of women had unrealistic weight loss expectations. Those who sought surgery expected to lose 47.6 +/- 9.3% of initial weight, compared with 24.8 +/- 8.7% for those who enrolled in behavioral weight control. These findings suggest that women with extreme obesity who seek bariatric surgery should be screened for psychosocial complications. Those determined to have significant psychiatric distress should be referred for behavioral or pharmacological treatment to alleviate their suffering. Long-term studies are needed to provide definitive guidance concerning the relationship between preoperative psychopathology and the outcome of bariatric surgery.

Aerosol Optical Depth Measurements by Airborne Sun Photometer in SOLVE II: Comparisons to SAGE III, POAM III and Airborne Spectrometer Measurements

NASA Technical Reports Server (NTRS)

Russell, P.; Livingston, J.; Schmid, B.; Eilers, J.; Kolyer, R.; Redemann, J.; Ramirez, S.; Yee, J-H.; Swartz, W.; Shetter, R.

2004-01-01

The 14-channel NASA Ames Airborne Tracking Sunphotometer (AATS-14) measured solar-beam transmission on the NASA DC-8 during the Second SAGE III Ozone Loss and Validation Experiment (SOLVE II). This paper presents AATS-14 results for multiwavelength aerosol optical depth (AOD), including its spatial structure and comparisons to results from two satellite sensors and another DC-8 instrument. These are the Stratospheric Aerosol and Gas Experiment III (SAGE III), the Polar Ozone and Aerosol Measurement III (POAM III) and the Direct beam Irradiance Airborne Spectrometer (DIAS).

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 ).

Synthesis and spectroscopic studies of biologically active compounds derived from oxalyldihydrazide and benzil, and their Cr(III), Fe(III) and Mn(III) complexes.

PubMed

Singh, D P; Kumar, Ramesh; Singh, Jitender

2009-04-01

A new series of complexes have been synthesized by template condensation of oxalyldihydrazide and benzil in methanolic medium in the presence of trivalent chromium, manganese and iron salts forming complexes of the type [M(C(32)H(24)N(8)O(4))X]X(2) where M = Cr(III), Mn(III), Fe(III) and X = Cl(-1), NO(3)(-1), CH(3)COO(-1). The complexes have been characterized with the help of elemental analyses, conductance measurements, magnetic susceptibility measurements, electronic, NMR, infrared and far infrared spectral studies. On the basis of these studies, a five coordinate square pyramidal geometry has been proposed for all these complexes. The biological activities of the metal complexes have been tested in vitro against a number of pathogenic bacteria to assess their inhibiting potential. Some of these complexes have been found to exhibit remarkable antibacterial activities.

An investigation of the iron-sulphur proteins of benzene dioxygenase from Pseudomonas putida by electron-spin-resonance spectroscopy.

PubMed Central

Geary, P J; Saboowalla, F; Patil, D; Cammack, R

1984-01-01

Benzene dioxygenase from Pseudomonas putida comprises three components, namely a flavoprotein (NADH:ferredoxin oxidoreductase; Mr 81000), an intermediate electron-transfer protein, or ferredoxin (Mr 12000) with a [2Fe-2S] cluster, and a terminal dioxygenase containing two [2Fe-2S] iron-sulphur clusters (Mr 215000), which requires two additional Fe2+ atoms/molecule for oxygenase activity. The ferredoxin and the dioxygenase give e.s.r. signals in the reduced state with rhombic symmetry and average g values of 1.92 and 1.896 respectively. The mid-point redox potentials were determined by e.s.r. titration at pH 7.0 to be -155 mV and -112 mV respectively. The signal from the dioxygenase shows pronounced g anisotropy and most closely resembles those of 4-methoxybenzoate mono-oxygenase from Pseudomonas putida and the [2Fe-2S] 'Rieske' proteins of the quinone-cytochrome c region of electron-transport chains of respiration and photosynthesis. PMID:6324743

Theoretical study of the magnetic exchange coupling behavior substituting Cr(III) with Mo(III) in cyano-bridged transition metal complexes

NASA Astrophysics Data System (ADS)

Zhang, Yi-Quan; Luo, Cheng-Lin

Molecular magnetism in a series of cyano-bridged first and second transition metal complexes has been investigated using density functional theory (DFT) combined with the broken-symmetry (BS) approach. Several exchange-correlation (XC) functionals in the ADF package were used to investigate complexes I [-(Me3tacn)2(cyclam)NiMo2(CN)6]2+, II [-(Me3tacn)2(cyclam)Ni-Cr2(CN)6]2+, III [(Me3tacn)6MnMo6(CN)18]2+, and IV [(Me3tacn)6MnCr6(CN)18]2+ (Me3tacn = N,N?,N‴-trimethyl-1,4,7-triazacyclononane). For models A (the molded structure of complex I) and B (the modeled structure of complex II), all the XCs given qualitatively reasonable results and predict ferromagnetic coupling character between M (M = MoIII for A or CrIII for B) and NiII in coincidence with the experimental results (see Tables and ). The calculated using Operdew, OPBE, O3LYP, and B3LYP functionals and experimental J values show that substituting CrIII with MoIII will enhance the ferromagnetic exchange coupling interactions. But VWN, PW91, PBE, VSXC, and tau-HCTH functionals have no way to differentiate the relative strength of the intramolecular magnetic exchange coupling interactions of A and B correctly. For models C (the modeled structure of complex III) and D (the modeled structure of complex IV), all the XCs in ADF and B3LYP in Gaussian 03 with several basis sets show that substituting CrIII with MoIII will enhance the antiferromagnetic exchange coupling interactions. From the above calculations, the substitution of CrIII by MoIII will enhance the magnetic coupling interactions, whether the magnetic coupling interactions are ferro- or antiferromagnetic. Moreover, Kahn's model was applied to investigate the above facts.

The mass distribution of Population III stars

NASA Astrophysics Data System (ADS)

Fraser, M.; Casey, A. R.; Gilmore, G.; Heger, A.; Chan, C.

2017-06-01

Extremely metal-poor (EMP) stars are uniquely informative on the nature of massive Population III stars. Modulo a few elements that vary with stellar evolution, the present-day photospheric abundances observed in EMP stars are representative of their natal gas cloud composition. For this reason, the chemistry of EMP stars closely reflects the nucleosynthetic yields of supernovae from massive Population III stars. Here we collate detailed abundances of 53 EMP stars from the literature and infer the masses of their Population III progenitors. We fit a simple initial mass function (IMF) to a subset of 29 of the inferred Population III star masses, and find that the mass distribution is well represented by a power-law IMF with exponent α = 2.35^{+0.29}_{-0.24}. The inferred maximum progenitor mass for supernovae from massive Population III stars is M_{max} = 87^{+13}_{-33} M⊙, and we find no evidence in our sample for a contribution from stars with masses above ˜120 M⊙. The minimum mass is strongly consistent with the theoretical lower mass limit for Population III supernovae. We conclude that the IMF for massive Population III stars is consistent with the IMF of present-day massive stars and there may well have formed stars much below the supernova mass limit that could have survived to the present day.

SDSS-III

Science.gov Websites

Mexico. SDSS-III consists of four surveys, each focused on a different scientific theme. Click on one of Collaboration including the University of Arizona, the Brazilian Participation Group, Brookhaven National Laboratory, Carnegie Mellon University, University of Florida, the French Participation Group, the German

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…

Zwitterion-functionalized polymer microspheres as a sorbent for solid phase extraction of trace levels of V(V), Cr(III), As(III), Sn(IV), Sb(III) and Hg(II) prior to their determination by ICP-MS.

PubMed

Jia, Xiaoyu; Gong, Dirong; Zhao, Junyi; Ren, Hongyun; Wang, Jiani; Zhang, Xian

2018-03-19

This paper describes the preparation of zwitterion-functionalized polymer microspheres (ZPMs) and their application to simultaneous enrichment of V(V), Cr(III), As(III), Sn(IV), Sb(III) and Hg(II) from environmental water samples. The ZPMs were prepared by emulsion copolymerization of ethyl methacrylate, 2-diethylaminoethyl methacrylate and triethylene glycol dimethyl acrylate followed by modification with 1,3-propanesultone. The components were analyzed by elemental analyses as well as Fourier transform infrared spectroscopy, and the structures were characterized by scanning electron microscopy and transmission electron microscopy. The ZPMs were packed into a mini-column for on-line solid-phase extraction (SPE) of the above metal ions. Following extraction with 40 mM NH 4 NO 3 and 0.5 M HNO 3 solution, the ions were quantified by ICP-MS. Under the optimized conditions, the enrichment factors (from a 40 mL sample) are up to 60 for the ions V(V), As(III), Sb(III) and Hg(II), and 55 for Cr(III) and Sn(IV). The detection limits are 1.2, 3.4, 1.0, 3.7, 2.1 and 1.6 ng L -1 for V(V), Cr(III), As(III), Sn(IV), Sb(III) and Hg(II), respectively, and the relative standard deviations (RSDs) are below 5.2%. The feasibility and accuracy of the method were validated by successfully analyzing six certified reference materials as well as lake, well and river waters. Graphical abstract Zwitterion-functionalized polymer microspheres (ZPMs) were prepared and packed into a mini-column for on-line solid-phase extraction (SPE) via pump 1. Then V(V), Cr(III), As(III), Sn(IV), Sb(III) and Hg(II) ions in environmental waters were eluted and submitted to ICP-MS via pump 2.

Iodine(III) Reagents in Radical Chemistry

PubMed Central

2017-01-01

Conspectus The chemistry of hypervalent iodine(III) compounds has gained great interest over the past 30 years. Hypervalent iodine(III) compounds show valuable ionic reactivity due to their high electrophilicity but also express radical reactivity as single electron oxidants for carbon and heteroatom radical generation. Looking at ionic chemistry, these iodine(III) reagents can act as electrophiles to efficiently construct C–CF3, X–CF3 (X = heteroatom), C–Rf (Rf = perfluoroalkyl), X–Rf, C–N3, C–CN, S–CN, and C–X bonds. In some cases, a Lewis or a Bronsted acid is necessary to increase their electrophilicity. In these transformations, the iodine(III) compounds react as formal “CF3+”, “Rf+”, “N3+”, “Ar+”, “CN+”, and “X+” equivalents. On the other hand, one electron reduction of the I(III) reagents opens the door to the radical world, which is the topic of this Account that focuses on radical reactivity of hypervalent iodine(III) compounds such as the Togni reagent, Zhdankin reagent, diaryliodonium salts, aryliodonium ylides, aryl(cyano)iodonium triflates, and aryl(perfluoroalkyl)iodonium triflates. Radical generation starting with I(III) reagents can also occur via thermal or light mediated homolysis of the weak hypervalent bond in such reagents. This reactivity can be used for alkane C–H functionalization. We will address important pioneering work in the area but will mainly focus on studies that have been conducted by our group over the last 5 years. We entered the field by investigating transition metal free single electron reduction of Togni type reagents using the readily available sodium 2,2,6,6-tetramethylpiperidine-1-oxyl salt (TEMPONa) as an organic one electron reductant for clean generation of the trifluoromethyl radical and perfluoroalkyl radicals. That valuable approach was later successfully also applied to the generation of azidyl and aryl radicals starting with the corresponding benziodoxole (Zhdankin reagent

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.

A possible role for chromium(III) in genotoxicity.

PubMed

Snow, E T

1991-05-01

Chromium is found in the environment in two major forms: reduced CrIII and CrVI, or chromate. Chromate, the most biologically active species, is readily taken up by living cells and reduced intracellularly, via reactive intermediates, to stable CrIII species. CrIII, the most abundant form of chromium in the environment, does not readily cross cell membranes and is relatively inactive in vivo. However, intracellular CrIII can react slowly with both nucleic acids and proteins and can be genotoxic. We have investigated the genotoxicity of CrIII in vitro using a DNA replication assay and in vivo by CaCl2-mediated transfection of chromium-treated DNA into Escherichia coli. When DNA replication was measured on a CrIII-treated template using purified DNA polymerases (either bacterial or mammalian), both the rate of DNA replication and the amount of incorporation per polymerase binding event (processivity) were greatly increased relative to controls. When transfected into E. coli, CrIII-treated M13mp2 bacteriophage DNA showed a dose-dependent increase in mutation frequency. These results suggest that CrIII alters the interaction between the DNA template and the polymerase such that the binding strength of the DNA polymerase is increased and the fidelity of DNA replication is decreased. These interactions may contribute to the mutagenicity of chromium ions in vivo and suggest that CrIII can contribute to chromium-mediated carcinogenesis.

One of the possible mechanisms for the inhibition effect of Tb(III) on peroxidase activity in horseradish (Armoracia rusticana) treated with Tb(III).

PubMed

Guo, Shaofen; Cao, Rui; Lu, Aihua; Zhou, Qing; Lu, Tianhong; Ding, Xiaolan; Li, Chaojun; Huang, Xiaohua

2008-05-01

One of the possible mechanisms for the inhibition effect of Tb(III) on peroxidase activity in horseradish (Armoracia rusticana) treated with Tb(III) was investigated using some biophysical and biochemical methods. Firstly, it was found that a large amount of Tb(III) can be distributed on the cell wall, that some Tb(III) can enter into the horseradish cell, indicating that peroxidase was mainly distributed on cell wall, and thus that Tb(III) would interact with horseradish peroxidase (HRP) in the plant. In addition, peroxidase bioactivity was decreased in the presence of Tb(III). Secondly, a new peroxidase-containing Tb(III) complex (Tb-HRP) was obtained from horseradish after treatment with Tb(III); the molecular mass of Tb-HRP is near 44 kDa and the pI is about 8.80. Thirdly, the electrocatalytic activity of Tb-HRP is much lower than that of HRP obtained from horseradish without treatment with Tb(III). The decrease in the activity of Tb-HRP is due to the destruction (unfolding) of the conformation in Tb-HRP. The planarity of the heme active center in the Tb-HRP molecule was increased and the extent of exposure of Fe(III) in heme was decreased, leading to inhibition of the electron transfer. The microstructure change in Tb-HRP might be the result of the inhibition effect of Tb(III) on peroxidase activity in horseradish.

National Coastal Condition Report III Factsheet

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.

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.

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 [Reserved] 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 [Reserved] ...

Mn(II) Oxidation by the Multicopper Oxidase Complex Mnx: A Coordinated Two-Stage Mn(II)/(III) and Mn(III)/(IV) Mechanism.

PubMed

Soldatova, Alexandra V; Romano, Christine A; Tao, Lizhi; Stich, Troy A; Casey, William H; Britt, R David; Tebo, Bradley M; Spiro, Thomas G

2017-08-23

The bacterial manganese oxidase MnxG of the Mnx protein complex is unique among multicopper oxidases (MCOs) in carrying out a two-electron metal oxidation, converting Mn(II) to MnO 2 nanoparticles. The reaction occurs in two stages: Mn(II) → Mn(III) and Mn(III) → MnO 2 . In a companion study , we show that the electron transfer from Mn(II) to the low-potential type 1 Cu of MnxG requires an activation step, likely forming a hydroxide bridge at a dinuclear Mn(II) site. Here we study the second oxidation step, using pyrophosphate (PP) as a Mn(III) trap. PP chelates Mn(III) produced by the enzyme and subsequently allows it to become a substrate for the second stage of the reaction. EPR spectroscopy confirms the presence of Mn(III) bound to the enzyme. The Mn(III) oxidation step does not involve direct electron transfer to the enzyme from Mn(III), which is shown by kinetic measurements to be excluded from the Mn(II) binding site. Instead, Mn(III) is proposed to disproportionate at an adjacent polynuclear site, thereby allowing indirect oxidation to Mn(IV) and recycling of Mn(II). PP plays a multifaceted role, slowing the reaction by complexing both Mn(II) and Mn(III) in solution, and also inhibiting catalysis, likely through binding at or near the active site. An overall mechanism for Mnx-catalyzed MnO 2 production from Mn(II) is presented.

Synthesis, spectroscopic, thermal and anticancer studies of metal-antibiotic chelations: Ca(II), Fe(III), Pd(II) and Au(III) chloramphenicol complexes

NASA Astrophysics Data System (ADS)

Al-Khodir, Fatima A. I.; Refat, Moamen S.

2016-09-01

Four Ca(II), Fe(III), Pd(II) and Au(III) complexes of chloramphenicol drug have been synthesized and well characterized using elemental analyses, (infrared, electronic, and 1H-NMR) spectra, magnetic susceptibility measurement, and thermal analyses. Infrared spectral data show that the chloramphenicol drug coordinated to Ca(II), Pd(II) and Au(III) metal ions through two hydroxyl groups with 1:1 or 1:2 M ratios, but Fe(III) ions chelated towards chloramphenicol drug via the oxygen and nitrogen atoms of amide group with 1:2 ratio based on presence of keto↔enol form. The X-ray powder diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscopy (TEM) techniques were used to identify the nano-size particles of both iron(III) and gold(III) chloramphenicol complexes. The antimicrobial assessments of the chloramphenicol complexes were scanned and collected the results against of some kind of bacteria and fungi. The cytotoxic activity of the gold(III) complex was tested against the human colon carcinoma (HCT-116) and human hepatocellular carcinoma (HepG-2) tumor cell lines.

Fe(III) and S0 reduction by Pelobacter carbinolicus

USGS Publications Warehouse

Lovley, D.R.; Phillips, E.J.P.; Lonergan, D.J.; Widma, P.K.

1995-01-01

There is a close phylogenetic relationship between Pelobacter species and members of the genera Desulfuromonas and Geobacter, and yet there has been a perplexing lack of physiological similarities. Pelobacter species have been considered to have a fermentative metabolism. In contrast, Desulfuromonas and Geobacter species have a respiratory metabolism with Fe(III) serving as the common terminal electron acceptor in all species. However, the ability of Pelobacter species to reduce Fe(III) had not been previously evaluated. When a culture of Pelobacter carbinolicus that had grown by fermentation of 2,3- butanediol was inoculated into the same medium supplemented with Fe(III), the Fe(III) was reduced. There was less accumulation of ethanol and more production of acetate in the presence of Fe(III). P. carbinolicus grew with ethanol as the sole electron donor and Fe(III) as the sole electron acceptor. Ethanol was metabolized to acetate. Growth was also possible on Fe(III) with the oxidation of propanol to propionate or butanol to butyrate if acetate was provided as a carbon source. P. carbinolicus appears capable of conserving energy to support growth from Fe(III) respiration as it also grew with H2 or formate as the electron donor and Fe(III) as the electron acceptor. Once adapted to Fe(III) reduction, P. carbinolicus could also grow on ethanol or H2 with S0 as the electron acceptor. P. carbinolicus did not contain detectable concentrations of the c-type cytochromes that previous studies have suggested are involved in electron transport to Fe(III) in other organisms that conserve energy to support growth from Fe(III) reduction. These results demonstrate that P. carbinolicus may survive in some sediments as an Fe(III) or S0 reducer rather than growing fermentatively on rare substrates or syntrophically as an ethanol-oxidizing acetogen. These studies also suggest that the ability to use Fe(III) as a terminal electron acceptor may be an important unifying feature of the

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.

Interaction of Triapine and related thiosemicarbazones with iron(III)/(II) and gallium(III): a comparative solution equilibrium study†

PubMed Central

Enyedy, Éva A.; Primik, Michael F.; Kowol, Christian R.; Arion, Vladimir B.; Kiss, Tamás; Keppler, Bernhard K.

2012-01-01

Stoichiometry and stability of GaIII, FeIII, FeII complexes of Triapine and five related α-N heterocyclic thiosemicarbazones with potential antitumor activity have been determined by pH-potentiometry, UV-vis spectrophotometry, 1H NMR spectroscopy, and spectrofluorimetry in aqueous solution (with 30% DMSO), together with the characterization of the proton dissociation processes. Additionally, the redox properties of the iron complexes were studied by cyclic voltammetry at various pH values. Formation of high stability bis-ligand complexes was found in all cases, which are predominant at physiological pH with FeIII/FeII, whilst only at the acidic pH range with GaIII. The results show that among the thiosemicarbazones with various substituents the N-terminal dimethylation does not exert a measurable effect on the redox potential, but has the highest impact on the stability of the complexes as well as the cytotoxicity, especially in the absence of a pyridine-NH2 group in the molecule. In addition the fluorescence properties of the ligands in aqueous solution and their changes caused by GaIII were studied. PMID:21523301

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.

DSM-III as a research tool.

PubMed

Treece, C

1982-05-01

The author describes the use of the DSM-III's diagnostic criteria and classification system as a research instrument and discusses some of the advantages and drawbacks of DMS-III for a specific type of study. A rearrangement of the hierarchical order of the DSM-III diagnostic classes is suggested. This rearrangement provides for levels of certainty in analyzing interrater reliability and offers a simplified framework for summarizing group data. When this approach is combined with a structured interview and response format, it provides a flexible way of managing a large classification system for a smaller study without sacrificing standardization.

Hybrid organic-inorganic connectivity of NdIII(pyrazine-N,N'-dioxide)[CoIII(CN)6]3- coordination chains for creating near-infrared emissive Nd(iii) showing field-induced slow magnetic relaxation.

PubMed

Chorazy, Szymon; Charytanowicz, Tomasz; Wang, Junhao; Ohkoshi, Shin-Ichi; Sieklucka, Barbara

2018-05-29

A near-infrared emissive and magnetically anisotropic Nd(iii) complex is formed within a hybrid organic-inorganic {[NdIII(pzdo)(H2O)4][CoIII(CN)6]}·0.5(pzdo)·4H2O (1) (pzdo = pyrazine-N,N'-dioxide) ladder chain built of coexisting Nd-pzdo-Nd and Nd-NC-Co molecular bridges. 1 reveals two NdIII-centered properties, a field-induced slow magnetic relaxation of a single-ion origin with a thermal energy barrier of ΔE/kB = 51(2) K at Hdc = 1 kOe, and a near-infrared fluorescence sensitized by organic and inorganic linkers.

Distribution and Translocation of 141Ce (III) in Horseradish

PubMed Central

Guo, Xiaoshan; Zhou, Qing; Lu, Tianhong; Fang, Min; Huang, Xiaohua

2007-01-01

Background and Aims Rare earth elements (REEs) are used in agriculture and a large amount of them contaminate the environment and enter foods. The distribution and translocation of 141Ce (III) in horseradish was investigated in order to help understand the biochemical behaviour and toxic mechanism of REEs in plants. Method The distribution and translocation of 141Ce (III) in horseradish were investigated using autoradiography, liquid scintillation counting (LSC) and electron microscopic autoradiography (EMARG) techniques. The contents of 141Ce (III) and nutrient elements were analysed using an inductively coupled plasma-atomic emission spectrometer (ICP-AES). Results The results from autoradiography and LSC indicated that 141Ce (III) could be absorbed by horseradish and transferred from the leaf to the leaf-stalk and then to the root. The content of 141Ce (III) in different parts of horseradish was as follows: root > leaf-stalk > leaf. The uptake rates of 141Ce (III) in horseradish changed with the different organs and time. The content of 141Ce (III) in developing leaves was greater than that in mature leaves. The results from EMARG indicated that 141Ce (III) could penetrate through the cell membrane and enter the mesophyll cells, being present in both extra- and intra-cellular deposits. The contents of macronutrients in horseradish were decreased by 141Ce (III) treatment. Conclusions 141Ce (III) can be absorbed and transferred between organs of horseradish with time, and the distribution was found to be different at different growth stages. 141Ce (III) can enter the mesophyll cells via apoplast and symplast channels or via plasmodesmata. 141Ce (III) can disturb the metabolism of macronutrients in horseradish. PMID:17921527

Apolipoprotein C-III in triglyceride-rich lipoprotein metabolism.

PubMed

Ramms, Bastian; Gordts, Philip L S M

2018-06-01

Apolipoprotein (apo) C-III is a key player in triglyceride-rich lipoprotein metabolism and strongly associated with elevated plasma triglyceride levels. Several new studies added important insights on apoC-III and its physiological function confirming its promise as a valid therapeutic target. APOC3 is expressed in liver and intestine and regulates triglyceride-rich lipoprotein (TRL) catabolism and anabolism. The transcriptional regulation in both organs requires different regulatory elements. Clinical and preclinical studies established that apoC-III raises plasma triglyceride levels predominantly by inhibiting hepatic TRL clearance. Mechanistic insights into missense variants indicate accelerated renal clearance of apoC-III variants resulting in enhanced TRL catabolism. In contrast, an APOC3 gain-of-function variant enhances de novo lipogenesis and hepatic TRL production. Multiple studies confirmed the correlation between increased apoC-III levels and cardiovascular disease. This has opened up new therapeutic avenues allowing targeting of specific apoC-III properties in triglyceride metabolism. Novel in vivo models and APOC3 missense variants revealed unique mechanisms by which apoC-III inhibits TRL catabolism. Clinical trials with Volanesorsen, an APOC3 antisense oligonucleotide, report very promising lipid-lowering outcomes. However, future studies will need to address if acute apoC-III lowering will have the same clinical benefits as a life-long reduction.

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.

Comparison of APACHE III, APACHE IV, SAPS 3, and MPM0III and Influence of Resuscitation Status on Model Performance

PubMed Central

Gajic, Ognjen; Afessa, Bekele

2012-01-01

Background: There are few comparisons among the most recent versions of the major adult ICU prognostic systems (APACHE [Acute Physiology and Chronic Health Evaluation] IV, Simplified Acute Physiology Score [SAPS] 3, Mortality Probability Model [MPM]0III). Only MPM0III includes resuscitation status as a predictor. Methods: We assessed the discrimination, calibration, and overall performance of the models in 2,596 patients in three ICUs at our tertiary referral center in 2006. For APACHE and SAPS, the analyses were repeated with and without inclusion of resuscitation status as a predictor variable. Results: Of the 2,596 patients studied, 283 (10.9%) died before hospital discharge. The areas under the curve (95% CI) of the models for prediction of hospital mortality were 0.868 (0.854-0.880), 0.861 (0.847-0.874), 0.801 (0.785-0.816), and 0.721 (0.704-0.738) for APACHE III, APACHE IV, SAPS 3, and MPM0III, respectively. The Hosmer-Lemeshow statistics for the models were 33.7, 31.0, 36.6, and 21.8 for APACHE III, APACHE IV, SAPS 3, and MPM0III, respectively. Each of the Hosmer-Lemeshow statistics generated P values < .05, indicating poor calibration. Brier scores for the models were 0.0771, 0.0749, 0.0890, and 0.0932, respectively. There were no significant differences between the discriminative ability or the calibration of APACHE or SAPS with and without “do not resuscitate” status. Conclusions: APACHE III and IV had similar discriminatory capability and both were better than SAPS 3, which was better than MPM0III. The calibrations of the models studied were poor. Overall, models with more predictor variables performed better than those with fewer. The addition of resuscitation status did not improve APACHE III or IV or SAPS 3 prediction. PMID:22499827

Molybdenum and vanadium do not replace tungsten in the catalytically active forms of the three tungstoenzymes in the hyperthermophilic archaeon Pyrococcus furiosus.

PubMed Central

Mukund, S; Adams, M W

1996-01-01

Three different types of tungsten-containing enzyme have been previously purified from Pyrococcus furiosus (optimum growth temperature, 100 degrees C): aldehyde ferredoxin oxidoreductase (AOR), formaldehyde ferredoxin oxidoreductase (FOR), and glyceraldehyde-3-phosphate oxidoreductase (GAPOR). In this study, the organism was grown in media containing added molybdenum (but not tungsten or vanadium) or added vanadium (but not molybdenum or tungsten). In both cell types, there were no dramatic changes compared with cells grown with tungsten, in the specific activities of hydrogenase, ferredoxin:NADP oxidoreductase, or the 2-keto acid ferredoxin oxidoreductases specific for pyruvate, indolepyruvate, 2-ketoglutarate, and 2-ketoisovalerate. Compared with tungsten-grown cells, the specific activities of AOR, FOR, and GAPOR were 40, 74, and 1%, respectively, in molybdenum-grown cells, and 7, 0, and 0%, respectively, in vanadium-grown cells. AOR purified from vanadium-grown cells lacked detectable vanadium, and its tungsten content and specific activity were both ca. 10% of the values for AOR purified from tungsten-grown cells. AOR and FOR purified from molybdenum-grown cells contained no detectable molybdenum, and their tungsten contents and specific activities were > 70% of the values for the enzymes purified from tungsten-grown cells. These results indicate that P. furiosus uses exclusively tungsten to synthesize the catalytically active forms of AOR, FOR, and GAPOR, and active molybdenum- or vanadium-containing isoenzymes are not expressed when the cells are grown in the presence of these other metals. PMID:8550411

The genetic basis of energy conservation in the sulfate-reducing bacterium Desulfovibrio alaskensis G20

DOE PAGES

Price, Morgan N.; Ray, Jayashree; Wetmore, Kelly M.; ...

2014-10-31

Sulfate-reducing bacteria play major roles in the global carbon and sulfur cycles, but it remains unclear how reducing sulfate yields energy. To determine the genetic basis of energy conservation, we measured the fitness of thousands of pooled mutants of Desulfovibrio alaskensis G20 during growth in 12 different combinations of electron donors and acceptors. We show that ion pumping by the ferredoxin:NADH oxidoreductase Rnf is required whenever substrate-level phosphorylation is not possible. The uncharacterized complex Hdr/flox-1 (Dde_1207:13) is sometimes important alongside Rnf and may perform an electron bifurcation to generate more reduced ferredoxin from NADH to allow further ion pumping. Similarly,more » during the oxidation of malate or fumarate, the electron-bifurcating transhydrogenase NfnAB-2 (Dde_1250:1) is important and may generate reduced ferredoxin to allow additional ion pumping by Rnf. During formate oxidation, the periplasmic [NiFeSe] hydrogenase HysAB is required, which suggests that hydrogen forms in the periplasm, diffuses to the cytoplasm, and is used to reduce ferredoxin, thus providing a substrate for Rnf. We found that during hydrogen utilization, the transmembrane electron transport complex Tmc is important and may move electrons from the periplasm into the cytoplasmic sulfite reduction pathway. Finally, mutants of many other putative electron carriers have no clear phenotype, which suggests that they are not important under our growth conditions, although we cannot rule out genetic redundancy.« less

Studies on the mechanism of electron bifurcation catalyzed by electron transferring flavoprotein (Etf) and butyryl-CoA dehydrogenase (Bcd) of Acidaminococcus fermentans.

PubMed

Chowdhury, Nilanjan Pal; Mowafy, Amr M; Demmer, Julius K; Upadhyay, Vikrant; Koelzer, Sebastian; Jayamani, Elamparithi; Kahnt, Joerg; Hornung, Marco; Demmer, Ulrike; Ermler, Ulrich; Buckel, Wolfgang

2014-02-21

Electron bifurcation is a fundamental strategy of energy coupling originally discovered in the Q-cycle of many organisms. Recently a flavin-based electron bifurcation has been detected in anaerobes, first in clostridia and later in acetogens and methanogens. It enables anaerobic bacteria and archaea to reduce the low-potential [4Fe-4S] clusters of ferredoxin, which increases the efficiency of the substrate level and electron transport phosphorylations. Here we characterize the bifurcating electron transferring flavoprotein (EtfAf) and butyryl-CoA dehydrogenase (BcdAf) of Acidaminococcus fermentans, which couple the exergonic reduction of crotonyl-CoA to butyryl-CoA to the endergonic reduction of ferredoxin both with NADH. EtfAf contains one FAD (α-FAD) in subunit α and a second FAD (β-FAD) in subunit β. The distance between the two isoalloxazine rings is 18 Å. The EtfAf-NAD(+) complex structure revealed β-FAD as acceptor of the hydride of NADH. The formed β-FADH(-) is considered as the bifurcating electron donor. As a result of a domain movement, α-FAD is able to approach β-FADH(-) by about 4 Å and to take up one electron yielding a stable anionic semiquinone, α-FAD, which donates this electron further to Dh-FAD of BcdAf after a second domain movement. The remaining non-stabilized neutral semiquinone, β-FADH(•), immediately reduces ferredoxin. Repetition of this process affords a second reduced ferredoxin and Dh-FADH(-) that converts crotonyl-CoA to butyryl-CoA.

The genetic basis of energy conservation in the sulfate-reducing bacterium Desulfovibrio alaskensis G20

PubMed Central

Price, Morgan N.; Ray, Jayashree; Wetmore, Kelly M.; Kuehl, Jennifer V.; Bauer, Stefan; Deutschbauer, Adam M.; Arkin, Adam P.

2014-01-01

Sulfate-reducing bacteria play major roles in the global carbon and sulfur cycles, but it remains unclear how reducing sulfate yields energy. To determine the genetic basis of energy conservation, we measured the fitness of thousands of pooled mutants of Desulfovibrio alaskensis G20 during growth in 12 different combinations of electron donors and acceptors. We show that ion pumping by the ferredoxin:NADH oxidoreductase Rnf is required whenever substrate-level phosphorylation is not possible. The uncharacterized complex Hdr/flox-1 (Dde_1207:13) is sometimes important alongside Rnf and may perform an electron bifurcation to generate more reduced ferredoxin from NADH to allow further ion pumping. Similarly, during the oxidation of malate or fumarate, the electron-bifurcating transhydrogenase NfnAB-2 (Dde_1250:1) is important and may generate reduced ferredoxin to allow additional ion pumping by Rnf. During formate oxidation, the periplasmic [NiFeSe] hydrogenase HysAB is required, which suggests that hydrogen forms in the periplasm, diffuses to the cytoplasm, and is used to reduce ferredoxin, thus providing a substrate for Rnf. During hydrogen utilization, the transmembrane electron transport complex Tmc is important and may move electrons from the periplasm into the cytoplasmic sulfite reduction pathway. Finally, mutants of many other putative electron carriers have no clear phenotype, which suggests that they are not important under our growth conditions, although we cannot rule out genetic redundancy. PMID:25400629

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.

40 CFR 300.220 - Related Title III issues.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 27 2010-07-01 2010-07-01 false Related Title III issues. 300.220 Section 300.220 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SUPERFUND, EMERGENCY... PLAN Planning and Preparedness § 300.220 Related Title III issues. Other related Title III requirements...

Control of Fe(III) site occupancy on the rate and extent of microbial reduction of Fe(III) in nontronite

USGS Publications Warehouse

Jaisi, Deb P.; Kukkadapu, R.K.; Eberl, D.D.; Dong, H.

2005-01-01

A quantitative study was performed to understand how Fe(III) site occupancy controls Fe(III) bioreduction in nontronite by Shewanella putrefaciens CN32. NAu-1 and NAu-2 were nontronites and contained Fe(III) in different structural sites with 16 and 23% total iron (w/w), respectively, with almost all iron as Fe(III). Mo??ssbauer spectroscopy showed that Fe(III) was present in the octahedral site in NAu-1 (with a small amount of goethite), but in both the tetrahedral and the octahedral sites in NAu-2. Mo??ssbauer data further showed that the octahedral Fe(III) in NAu-2 existed in at least two environments- trans (M1) and cis (M2) sites. The microbial Fe(III) reduction in NAu-1 and NAu-2 was studied in batch cultures at a nontronite concentration of 5 mg/mL in bicarbonate buffer with lactate as the electron donor. The unreduced and bioreduced nontronites were characterized by X-ray diffraction (XRD), Mo??ssbauer spectroscopy, and transmission electron microscopy (TEM). In the presence of an electron shuttle, anthraquinone-2,6-disulfonate (AQDS), the extent of bioreduction was 11%-16% for NAu-1 but 28%-32% for NAu-2. The extent of reduction in the absence of AQDS was only 5%-7% for NAu-1 but 14%-18% for NAu-2. The control experiments with heat killed cells and without cells did not show any appreciable reduction (<2%). The extent of reduction in experiments performed with a dialysis membrane to separate cells from clays (without AQDS) was 2%-3% for NAu-1 but 5%-7% for NAu-2, suggesting that cells probably released an electron shuttling compound and/or Fe(III) chelator. The reduction rate was also faster in NAu-2 than that in NAu-1. Mo??ssbauer data of the bioreduced nontronite materials indicated that the Fe(III) reduction in NAu-1 was mostly from the presence of goethite, whereas the reduction in NAu-2 was due to the presence of the tetrahedral and trans-octahedral Fe(III) in the structure. The measured aqueous Fe(II) was negligible. As a result of bioreduction, the

Cytotoxic and genotoxic potential of Cr(VI), Cr(III)-nitrate and Cr(III)-EDTA complex in human hepatoma (HepG2) cells.

PubMed

Novotnik, Breda; Ščančar, Janez; Milačič, Radmila; Filipič, Metka; Žegura, Bojana

2016-07-01

Chromium (Cr) and ethylenediaminetetraacetate (EDTA) are common environmental pollutants and can be present in high concentrations in surface waters at the same time. Therefore, chelation of Cr with EDTA can occur and thereby stable Cr(III)-EDTA complex is formed. Since there are no literature data on Cr(III)-EDTA toxicity, the aim of our work was to evaluate and compare Cr(III)-EDTA cytotoxic and genotoxic activity with those of Cr(VI) and Cr(III)-nitrate in human hepatoma (HepG2) cell line. First the effect of Cr(VI), Cr(III)-nitrate and Cr(III)-EDTA on cell viability was studied in the concentration range from 0.04 μg mL(-1) to 25 μg mL(-1) after 24 h exposure. Further the influence of non-cytotoxic concentrations of Cr(VI), Cr(III)-nitrate and Cr(III)-EDTA on DNA damage and genomic stability was determined with the comet assay and cytokinesis block micronucleus cytome assay, respectively. Cell viability was decreased only by Cr(VI) at concentrations above 1.0 μg mL(-1). Cr(VI) at ≥0.2 μg mL(-1) and Cr(III) at ≥1.0 μg mL(-1) induced DNA damage, while after Cr(III)-EDTA exposure no formation DNA strand breaks was determined. Statistically significant formation of micronuclei was induced only by Cr(VI) at ≥0.2 μg mL(-1), while no influence on the frequency of nuclear buds nor nucleoplasmic bridges was observed at any exposure. This study provides the first evidence that Cr(III)-EDTA did not induce DNA damage and had no influence on the genomic stability of HepG2 cells. Copyright © 2016 Elsevier Ltd. All rights reserved.

The Distribution of Scaled Scores and Possible Floor Effects on the WISC-III and WAIS-III

ERIC Educational Resources Information Center

Whitaker, Simon; Wood, Christopher

2008-01-01

Objective: It has been suggested that, as the Wechsler Adult Intelligence Scale-Third Edition (WAIS-III) and the Wechsler Intelligence Scale for Children-Third Edition (WISC-III) give a scaled score of one even if a client scores a raw score of zero, these assessments may have a hidden floor effect at low IQ levels. The study looked for…

Competitive adsorption of As(III), As(V), Sb(III) and Sb(V) onto ferrihydrite in multi-component systems: Implications for mobility and distribution.

PubMed

Qi, Pengfei; Pichler, Thomas

2017-05-15

The simultaneous adsorption behavior and competitive interactions between As(III), As(V), Sb(III) and Sb(V) by ferrihydrite were evaluated in multi-component (binary, ternary, quaternary) systems. In binary systems, Sb(III) had a stronger inhibitory influence on As(III) adsorption than Sb(V) did, and As(V) had a stronger inhibitory effect on Sb(V) adsorption than As(III) did. In ternary systems, NO 3 - , PO 4 3- and SO 4 2- did not compete with the adsorption of As(III) and Sb(III). NO 3 - and SO 4 2- also had no distinct effect on the adsorption of As(V) and Sb(V), while PO 4 3- competed with As(V) and Sb(V) for surface sites. In quaternary systems, the simultaneous adsorption behavior of the four redox species was pH dependent. Sb(III) always showed the strongest adsorption affinity regardless of pH. At pH 3.5 As(III) showed the lowest affinity could be due to the presence and negative effect of Sb(III) and As(V). The Freundlich model provided a good fit for the simultaneous adsorption data under quaternary conditions. The study of competitive/simultaneous adsorption of the four possible redox species onto ferrihydrite contributed to a better understanding of their distribution, mobility and fate in the environment. Copyright © 2017 Elsevier B.V. All rights reserved.

Lanthanoplatins: emissive Eu(iii) and Tb(iii) complexes staining nucleoli targeted through Pt-DNA crosslinking.

PubMed

Singh, Khushbu; Singh, Swati; Srivastava, Payal; Sivakumar, Sri; Patra, Ashis K

2017-06-01

Two highly luminescent water-soluble heterometallic LnPt 2 complexes, [{cis-PtCl(NH 3 ) 2 } 2 Ln(L)(H 2 O)](NO 3 ) 2 (Ln = Eu (1), Tb (2)), have been designed for their selective nucleoli staining through formation of Pt-DNA crosslinks. The complexes showed significant cellular uptake and distinctive nucleoli localization through intrinsic emission from Eu III or Tb III observed through confocal fluorescence microscopy.

Role of the ancillary ligand N,N-dimethylaminoethanol in the sensitization of Eu(III) and Tb(III) luminescence in dimeric beta-diketonates.

PubMed

Eliseeva, Svetlana V; Kotova, Oxana V; Gumy, Frédéric; Semenov, Sergey N; Kessler, Vadim G; Lepnev, Leonid S; Bünzli, Jean-Claude G; Kuzmina, Natalia P

2008-04-24

Two types of dimeric complexes [Ln2(hfa)6(mu2-O(CH2)2NHMe2)2] and [Ln(thd)2(mu2,eta2-O(CH2)2NMe2)]2 (Ln = YIII, EuIII, GdIII, TbIII, TmIII, LuIII; hfa- = hexafluoroacetylacetonato, thd- = dipivaloylmethanato) are obtained by reacting [Ln(hfa)3(H2O)2] and [Ln(thd)3], respectively, with N,N-dimethylaminoethanol in toluene and are fully characterized. X-ray single crystal analysis performed for the TbIII compounds confirms their dimeric structure. The coordination mode of N,N-dimethylaminoethanol depends on the nature of the beta-diketonate. In [Tb2(hfa)6(mu2-O(CH2)2NHMe2)2], eight-coordinate TbIII ions adopt distorted square antiprismatic coordination environments and are O-bridged by two zwitterionic N,N-dimethylaminoethanol ligands with a Tb1...Tb2 separation of 3.684(1) A. In [Tb(thd)2(mu2,eta2-O(CH2)2NMe2)]2, the N,N-dimethylaminoethanol acts as chelating-bridging O,N-donor anion and the TbIII ions are seven-coordinate; the Tb1...Tb1A separation amounts to 3.735(2) A within centrosymmetric dimers. The dimeric complexes are thermally stable up to 180 degrees C, as shown by thermogravimetric analysis, and their volatility is sufficient for quantitative sublimation under reduced pressure. The EuIII and TbIII dimers display metal-centered luminescence, particularly [Eu2(hfa)6(O(CH2)2NHMe2)2] (quantum yield Q(L)Ln = 58%) and [Tb(thd)2(O(CH2)2NMe2)]2 (32%). Consideration of energy migration paths within the dimers, based on the study of both pure and EuIII- or TbIII-doped (0.01-0.1 mol %) LuIII analogues, leads to the conclusion that both the beta-diketone and N,N-dimethylaminoethanol ligands contribute significantly to the sensitization process of the EuIII luminescence. The ancillary ligand increases considerably the luminescence of [Eu2(hfa)6(O(CH2)2NHMe2)2], compared to [Ln(hfa)3(H2O)2], through the formation of intra-ligand states while it is detrimental to TbIII luminescence in both beta-diketonates. Thin films of the most luminescent compound [Eu2(hfa)6(O(CH2

WHERE ARE THE LOW-MASS POPULATION III STARS?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ishiyama, Tomoaki; Sudo, Kae; Yokoi, Shingo

2016-07-20

We study the number and the distribution of low-mass Population III (Pop III) stars in the Milky Way. In our numerical model, hierarchical formation of dark matter minihalos and Milky-Way-sized halos are followed by a high-resolution cosmological simulation. We model the Pop III formation in H{sub 2} cooling minihalos without metal under UV radiation of the Lyman–Werner bands. Assuming a Kroupa initial mass function (IMF) from 0.15 to 1.0 M {sub ⊙} for low-mass Pop III stars, as a working hypothesis, we try to constrain the theoretical models in reverse by current and future observations. We find that the survivorsmore » tend to concentrate on the center of halo and subhalos. We also evaluate the observability of Pop III survivors in the Milky Way and dwarf galaxies, and constraints on the number of Pop III survivors per minihalo. The higher latitude fields require lower sample sizes because of the high number density of stars in the galactic disk, the required sample sizes are comparable in the high- and middle-latitude fields by photometrically selecting low-metallicity stars with optimized narrow-band filters, and the required number of dwarf galaxies to find one Pop III survivor is less than 10 at <100 kpc for the tip of red giant stars. Provided that available observations have not detected any survivors, the formation models of low-mass Pop III stars with more than 10 stars per minihalo are already excluded. Furthermore, we discuss the way to constrain the IMF of Pop III stars at a high mass range of ≳10 M {sub ⊙}.« less

Endemic human paragonimiasis in Equatorial Guinea. Detection of the existence of endemic human paragonimiasis in Equatorial Guinea as a result of an integrated sanitary programme.

PubMed

Simarro, P P; Alamo, A; Sima, F O; Roche, J; Mir, M; Ndong, P

1991-07-01

Between February and April 1990 the first five cases of human paragonimiasis, tentatively due to Paragonimus africanus, have been detected in Equatorial Guinea, thanks to the normal activities of the National Schistosomiasis Project and its coordination with the National Tuberculosis Project.

The effect of surface charge on the thermal stability and ice recrystallization inhibition activity of antifreeze protein III (AFP III).

PubMed

Deller, R C; Carter, B M; Zampetakis, I; Scarpa, F; Perriman, A W

2018-01-01

The aim of this study was to examine the effect of chemical cationization on the structure and function of antifreeze protein III (AFP III) over an extreme temperature range (-40°C to +90°C) using far-UV synchrotron radiation circular dichroism (SRCD) and ice recrystallization inhibition (IRI) assays. Chemical cationization was able to produce a modified AFP III with a net cationic charge at physiological pH that had enhanced resistance to denaturation at elevated temperatures, with no immediate negative impact on protein structure at subzero temperatures. Furthermore, cationized AFP III retained an IRI activity similar to that of native AFP III. Consequently, chemical cationization may provide a pathway to the development of more robust antifreeze proteins as supplementary cryoprotectants in the cryopreservation of clinically relevant cells. Copyright © 2017. Published by Elsevier Inc.

Strong and anisotropic superexchange in the single-molecule magnet (SMM) [MnIII(6)OsIII]3+: promoting SMM behavior through 3d-5d transition metal substitution.

PubMed

Hoeke, Veronika; Stammler, Anja; Bögge, Hartmut; Schnack, Jürgen; Glaser, Thorsten

2014-01-06

The reaction of the in situ generated trinuclear triplesalen complex [(talent-Bu2)MnIII3(solv)n]3+ with (Ph4P)3[OsIII(CN)6] and NaClO4·H2O affords [MnIII6OsIII](ClO4)3 (= [{(talent-Bu2)MnIII3}2{OsIII(CN)6}](ClO4)3) in the presence of the oxidizing agent [(tacn)2NiIII](ClO4)3 (tacn =1,4,7-triazacyclononane), while the reaction of [(talent-Bu2)MnIII3(solv)n]3+ with K4[OsII(CN)6] and NaClO4·H2O yields [MnIII6OsII](ClO4)2 under an argon atmosphere. The molecular structure of [MnIII6OsIII]3+ as determined by single-crystal X-ray diffraction is closely related to the already published [MnIII6Mc]3+ complexes (Mc = CrIII, FeIII, CoIII, MnIII). The half-wave potential of the OsIII/OsII couple is E1/2 = 0.07 V vs Fc+/Fc. The FT-IR and electronic absorption spectra of [MnIII6OsII]2+ and [MnIII6OsIII]3+ exhibit distinct features of dicationic and tricationic [MnIII6Mc]n+ complexes, respectively. The dc magnetic data (μeff vs T, M vs B, and VTVH) of [MnIII6OsII]2+ are successfully simulated by a full-matrix diagonalization of a spin-Hamiltonian including isotropic exchange, zero-field splitting with full consideration of the relative orientation of the D-tensors, and Zeeman interaction, indicating antiferromagnetic MnIII–MnIII interactions within the trinuclear triplesalen subunits (JMn–Mn(1) = −(0.53 ± 0.01) cm–1, Ĥex = −2∑iIII6OsIII]3+ are excellently reproduced assuming an anisotropic Ising-like OsIII–MnIII superexchange with a nonzero component JOs–Mn(aniso) = −(11.0 ± 1.0) cm–1 along the Os–Mn direction, while JMn–Mn = −(0.9 ± 0.1) cm–1 and DMn = −(3.0 ± 1.0) cm–1. Alternating current measurements indicate a slower relaxation of the magnetization in the SMM [MnIII6OsIII]3+ compared to the 3d analogue [MnIII6FeIII]3+ due to the

Improved sensitivity for W-band Gd(III)-Gd(III) and nitroxide-nitroxide DEER measurements with shaped pulses

NASA Astrophysics Data System (ADS)

Bahrenberg, Thorsten; Rosenski, Yael; Carmieli, Raanan; Zibzener, Koby; Qi, Mian; Frydman, Veronica; Godt, Adelheid; Goldfarb, Daniella; Feintuch, Akiva

2017-10-01

Chirp and shaped pulses have been recently shown to be highly advantageous for improving sensitivity in DEER (double electron-electron resonance, also called PELDOR) measurements due to their large excitation bandwidth. The implementation of such pulses for pulse EPR has become feasible due to the availability of arbitrary waveform generators (AWG) with high sampling rates to support pulse shaping for pulses with tens of nanoseconds duration. Here we present a setup for obtaining chirp pulses on our home-built W-band (95 GHz) spectrometer and demonstrate its performance on Gd(III)-Gd(III) and nitroxide-nitroxide DEER measurements. We carried out an extensive optimization procedure on two model systems, Gd(III)-PyMTA-spacer-Gd(III)-PyMTA (Gd-PyMTA ruler; zero-field splitting parameter (ZFS) D ∼ 1150 MHz) as well as nitroxide-spacer-nitroxide (nitroxide ruler) to evaluate the applicability of shaped pulses to Gd(III) complexes and nitroxides, which are two important classes of spin labels used in modern DEER/EPR experiments. We applied our findings to ubiquitin, doubly labeled with Gd-DOTA-monoamide (D ∼ 550 MHz) as a model for a system with a small ZFS. Our experiments were focused on the questions (i) what are the best conditions for positioning of the detection frequency, (ii) which pump pulse parameters (bandwidth, positioning in the spectrum, length) yield the best signal-to-noise ratio (SNR) improvements when compared to classical DEER, and (iii) how do the sample's spectral parameters influence the experiment. For the nitroxide ruler, we report an improvement of up to 1.9 in total SNR, while for the Gd-PyMTA ruler the improvement was 3.1-3.4 and for Gd-DOTA-monoamide labeled ubiquitin it was a factor of 1.8. Whereas for the Gd-PyMTA ruler the two setups pump on maximum and observe on maximum gave about the same improvement, for Gd-DOTA-monoamide a significant difference was found. In general the choice of the best set of parameters depends on the D

High efficiency III-nitride light-emitting diodes

DOEpatents

Crawford, Mary; Koleske, Daniel; Cho, Jaehee; Zhu, Di; Noemaun, Ahmed; Schubert, Martin F; Schubert, E. Fred

2013-05-28

Tailored doping of barrier layers enables balancing of the radiative recombination among the multiple-quantum-wells in III-Nitride light-emitting diodes. This tailored doping enables more symmetric carrier transport and uniform carrier distribution which help to reduce electron leakage and thus reduce the efficiency droop in high-power III-Nitride LEDs. Mitigation of the efficiency droop in III-Nitride LEDs may enable the pervasive market penetration of solid-state-lighting technologies in high-power lighting and illumination.

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…

Modal Profiles for the WISC-III.

ERIC Educational Resources Information Center

Pritchard, David A.; Livingston, Ronald B.; Reynolds, Cecil R.; Moses, James A., Jr.

2000-01-01

Presents a normative typology for classifying the Wechsler Intelligence Scale for Children-Third Edition (WISC-III) factor index profiles according to profile shape. Current analyses indicate that overall profile level accounted for a majority of the variance in WISC-III index scores, but a considerable proportion of the variance was because of…

Identification and functional analysis of cytochrome P450 complement in Streptomyces virginiae IBL14

PubMed Central

2013-01-01

Background As well known, both natural and synthetic steroidal compounds are powerful endocrine disrupting compounds (EDCs) which can cause reproductive toxicity and affect cellular development in mammals and thus are generally regarded as serious contributors to water pollution. Streptomyces virginiae IBL14 is an effective degradative strain for many steroidal compounds and can also catalyze the C25 hydroxylation of diosgenin, the first-ever biotransformation found on the F-ring of diosgenin. Results To completely elucidate the hydroxylation function of cytochrome P450 genes (CYPs) found during biotransformation of steroids by S. virginiae IBL14, the whole genome sequencing of this strain was carried out via 454 Sequencing Systems. The analytical results of BLASTP showed that the strain IBL14 contains 33 CYPs, 7 ferredoxins and 3 ferredoxin reductases in its 8.0 Mb linear chromosome. CYPs from S. virginiae IBL14 are phylogenetically closed to those of Streptomyces sp. Mg1 and Streptomyces sp. C. One new subfamily was found as per the fact that the CYP Svu001 in S. virginiae IBL14 shares 66% identity only to that (ZP_05001937, protein identifer) from Streptomyces sp. Mg1. Further analysis showed that among all of the 33 CYPs in S. virginiae IBL14, three CYPs are clustered with ferredoxins, one with ferredoxin and ferredoxin reductase and three CYPs with ATP/GTP binding proteins, four CYPs arranged with transcriptional regulatory genes and one CYP located on the upstream of an ATP-binding protein and transcriptional regulators as well as four CYPs associated with other functional genes involved in secondary metabolism and degradation. Conclusions These characteristics found in CYPs from S. virginiae IBL14 show that the EXXR motif in the K-helix is not absolutely conserved in CYP157 family and I-helix not absolutely essential for the CYP structure, too. Experimental results showed that both CYP Svh01 and CYP Svu022 are two hydroxylases, capable of bioconverting

Hyper III on ramp, front view

NASA Technical Reports Server (NTRS)

1969-01-01

The Hyper III was a low-cost test vehicle for an advanced lifting-body shape. Like the earlier M2-F1, it was a 'homebuilt' research aircraft, i.e., built at the Flight Research Center (FRC), later redesignated the Dryden Flight Research Center. It had a steel-tube frame covered with Dacron, a fiberglass nose, sheet aluminum fins, and a wing from an HP-11 sailplane. Construction was by volunteers at the FRC. Although the Hyper III was to be flown remotely in its initial tests, it was fitted with a cockpit for a pilot. On the Hyper III's only flight, it was towed aloft attached to a Navy SH-3 helicopter by a 400-foot cable. NASA research pilot Bruce Peterson flew the SH-3. After he released the Hyper III from the cable, NASA research pilot Milt Thompson flew the vehicle by radio control until the final approach when Dick Fischer took over control using a model-airplane radio-control box. The Hyper III flared, then landed and slid to a stop on Rogers Dry Lakebed. The Flight Research Center (FRC--as Dryden was named from 1959 until 1976) already had experience with testing small-scale aircraft using model-airplane techniques, but the first true remotely piloted research vehicle was the Hyper III, which flew only once in December 1969. At that time, the Center was engaged in flight research with a variety of reentry shapes called lifting bodies, and there was a desire both to expand the flight research experience with maneuverable reentry vehicles, including a high-performance, variable-geometry craft, and to investigate a remotely piloted flight research technique that made maximum use of a research pilot's skill and experience by placing him 'in the loop' as if he were in the cockpit. (There have been, as yet, no female research pilots assigned to Dryden.) The Hyper III as originally conceived was a stiletto-shaped lifting body that had resulted from a study at NASA's Langley Research Center in Hampton, Virginia. It was one of a number of hypersonic, cross

Disproportionation of hydroxylamine by water-soluble iron(III) porphyrinate compounds.

PubMed

Bari, Sara E; Amorebieta, Valentín T; Gutiérrez, María M; Olabe, José A; Doctorovich, Fabio

2010-01-01

The reactions of hydroxylamine (HA) with several water-soluble iron(III) porphyrinate compounds, namely iron(III) meso-tetrakis-(N-ethylpyridinium-2yl)-porphyrinate ([Fe(III)(TEPyP)](5+)), iron(III) meso-tetrakis-(4-sulphonatophenyl)-porphyrinate ([Fe(III)(TPPS)](3-)), and microperoxidase 11 ([Fe(III)(MP11)]) were studied for different [Fe(III)(Porph)]/[HA] ratios, under anaerobic conditions at neutral pH. Efficient catalytic processes leading to the disproportionation of HA by these iron(III) porphyrinates were evidenced for the first time. As a common feature, only N(2) and N(2)O were found as gaseous, nitrogen-containing oxidation products, while NH(3) was the unique reduced species detected. Different N(2)/N(2)O ratios obtained with these three porphyrinates strongly suggest distinctive mechanistic scenarios: while [Fe(III)(TEPyP)](5+) and [Fe(III)(MP11)] formed unknown steady-state porphyrinic intermediates in the presence of HA, [Fe(III)(TPPS)](3-) led to the well characterized soluble intermediate, [Fe(II)(TPPS)NO](4-). Free-radical formation was only evidenced for [Fe(III)(TEPyP)](5+), as a consequence of a metal centered reduction. We discuss the catalytic pathways of HA disproportionation on the basis of the distribution of gaseous products, free radicals formation, the nature of porphyrinic intermediates, the Fe(II)/Fe(III) redox potential, the coordinating capabilities of each complex, and the kinetic analysis. The absence of NO(2)(-) revealed either that no HAO-like activity was operative under our reaction conditions, or that NO(2)(-), if formed, was consumed in the reaction milieu.

Adsorption of Eu(III) onto roots of water hyacinth

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kelley, C.; Mielke, R.E.; Dimaquibo, D.

1999-05-01

The water hyacinth (Eichhornia crassipes) has drawn attention as a plant capable of removing pollutants, including toxic metals, from water. The authors are interested in the capacity of the water hyacinth to remediate aquatic environments that have been contaminated with the lanthanide metal, europium Eu(III). Using scanning electron microscopy (SEM) they have been able to determine that Eu(III) is adsorbed onto the surface of the roots from water and that the highest concentration of Eu(III) is on the root hairs. X-ray absorption spectroscopy (XAS) techniques were used to speciate the Eu(III) adsorbed onto the surface of the roots. The XASmore » data for Eu-contaminated water hyacinth roots provides evidence of a Eu-oxygen environment and establishes that Eu(III) is coordinated to 10--11 oxygen atoms at a distance of 2.44 {angstrom}. This likely involves binding of Eu(III) to the root via carboxylate groups and hydration of Eu(III) at the root surface.« less

Recent advances on biological production of difructose dianhydride III.

PubMed

Zhu, Yingying; Yu, Shuhuai; Zhang, Wenli; Zhang, Tao; Guang, Cuie; Mu, Wanmeng

2018-04-01

Difructose dianhydride III (DFA III) is a cyclic difructose containing two reciprocal glycosidic linkages. It is easily generated with a small amount by sucrose caramelization and thus occurs in a wide range of food-stuffs during food processing. DFA III has half sweetness but only 1/15 energy of sucrose, showing potential industrial application as low-calorie sucrose substitute. In addition, it displays many benefits including prebiotic effect, low cariogenicity property, and hypocholesterolemic effect, and improves absorption of minerals, flavonoids, and immunoglobulin G. DFA III is biologically produced from inulin by inulin fructotransferase (IFTase, EC 4.2.2.18). Plenty of DFA III-producing enzymes have been identified. The crystal structure of inulin fructotransferase has been determined, and its molecular modification has been performed to improve the catalytic activity and structural stability. Large-scale production of DFA III has been studied by various IFTases, especially using an ultrafiltration membrane bioreactor. In this article, the recent findings on physiological effects of DFA III are briefly summarized; the research progresses on identification, expression, and molecular modification of IFTase and large-scale biological production of DFA III by IFTase are reviewed in detail.

Genetics Home Reference: mitochondrial complex III deficiency

MedlinePlus

... DNA packaged in chromosomes within the cell nucleus (nuclear DNA). It is not clear why the severity ... deficiency Genetic Testing Registry: Mitochondrial complex III deficiency, nuclear type 2 Genetic Testing Registry: Mitochondrial complex III ...

Low-Cost III-V Solar Cells | Photovoltaic Research | NREL

Science.gov Websites

Low-Cost III-V Solar Cells Low-Cost III-V Solar Cells At present, the cost of III-V solar cells is to drastically lower the cost of these devices, while maintaining their conversion efficiency, thus costs in the production of high-efficiency III-V devices: the cost of the epitaxy and the single-crystal

Phase III of Early Restoration | NOAA Gulf Spill Restoration

Science.gov Websites

information about this phase of Early Restoration, including fact sheets on each project. The final Phase III 44 projects are documented in a final Record of Decision. Information about Phase III of Early Archive Home Phase III of Early Restoration Phase III of Early Restoration Beach habitat would be restored

Extreme [O III] Emitters at z ∼ 0.5

NASA Astrophysics Data System (ADS)

Li, Zhihui; Malkan, Matthew A.

2018-06-01

We have found a sample of extreme emission-line galaxies (EELGs) with strong [O III]λ5007 emission at z ∼ 0.5. Using broadband photometric selection and requiring small uncertainties in photometry, we searched the 14th Data Release of the Sloan Digital Sky Survey (SDSS) and found 2658 candidates with strong i-band excess (i – z ≤ r – i – 0.7). We further obtained 649 SDSS spectra of these objects, and visually identified 22 [O III] emitters lying at 0.40 < z < 0.63. Having constructed their ultraviolet–infrared spectral energy distributions, we found that they have fairly blue r – W2 and red W1 – W4 colors, indicative of strong, warm dust emission. Their rest-frame [O III]λ5007 equivalent widths are mostly 200–600 Å, and their high [O III]λ5007/Hβ ratios put them at the boundary of star-forming galaxies and active galactic nuclei on line ratio classification diagrams. The typical E(B–V) and electron temperature of [O III] emitters are ∼0.1–0.3 mag and ∼104 K, respectively. The lowest metallicity of our [O III] emitters with S/N[O III]λ4363 > 3 is 12 + log(O/H) = {7.98}-0.02+0.12, with a median value of {8.24}-0.04+0.05. Our [O III] emitters exhibit remarkably high line luminosity—18/22 have L [O III]λ5007 > 5 × 1042 erg s‑1 and 5/22 have L [O III]λ5007 > 1043 erg s‑1. Their estimated volume number density at z ∼ 0.5 is ∼2 × 10‑8 Mpc‑3, with L [O III]λ5007 down to ∼3 × 1042 erg s‑1. The cumulative number distribution of EELGs across different redshifts is indicative of a strong redshift evolution at the bright end of the [O III] luminosity function.

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.

Covalency in Americium(III) Hexachloride

DOE PAGES

Cross, Justin Neil; Su, Jing; Batista, Enrigue R.; ...

2017-06-14

Developing a better understanding of covalency (or orbital mixing) is of fundamental importance. Covalency occupies a central role in directing chemical and physical properties for almost any given compound or material. Hence, the concept of covalency has potential to generate broad and substantial scientific advances, ranging from biological applications to condensed matter physics. Given the importance orbital mixing combined with the difficultly in measuring covalency, estimating or inferring covalency often leads to fiery debate. Consider the 60-year controversy sparked by SEABORG and COWORKERS (1954) when it was proposed that covalency from 5f-orbitals contributed to the unique behavior of americium inmore » chloride matrixes. Herein, we describe the use of ligand K-edge X-ray absorption spectroscopy (XAS) and electronic structure calculations to quantify the extent of covalent bonding in – arguably – one of the most difficult systems to study, the Am–Cl interaction within AmCl 6 3-. We observed both 5fand 6d-orbital mixing with the Cl-3p orbitals; however, contributions from the 6d-orbitals were more substantial. Comparisons with the isoelectronic EuCl 6 3- indicated similar bonding for the Am III 6d- and Eu III 5d-orbitals. Meanwhile, the results confirmed SEABORG’S 1954 hypothesis that Am III 5f-orbital covalency was more substantial than 4forbital mixing for Eu III.« less

A multiplicity of factors contributes to selective RNA polymerase III occupancy of a subset of RNA polymerase III genes in mouse liver

PubMed Central

Canella, Donatella; Bernasconi, David; Gilardi, Federica; LeMartelot, Gwendal; Migliavacca, Eugenia; Praz, Viviane; Cousin, Pascal; Delorenzi, Mauro; Hernandez, Nouria; Hernandez, Nouria; Delorenzi, Mauro; Deplancke, Bart; Desvergne, Béatrice; Guex, Nicolas; Herr, Winship; Naef, Felix; Rougemont, Jacques; Schibler, Ueli; Deplancke, Bart; Guex, Nicolas; Herr, Winship; Guex, Nicolas; Andersin, Teemu; Cousin, Pascal; Gilardi, Federica; Gos, Pascal; Le Martelot, Gwendal; Lammers, Fabienne; Canella, Donatella; Gilardi, Federica; Raghav, Sunil; Fabbretti, Roberto; Fortier, Arnaud; Long, Li; Vlegel, Volker; Xenarios, Ioannis; Migliavacca, Eugenia; Praz, Viviane; Guex, Nicolas; Naef, Felix; Rougemont, Jacques; David, Fabrice; Jarosz, Yohan; Kuznetsov, Dmitry; Liechti, Robin; Martin, Olivier; Ross, Frederick; Sinclair, Lucas; Cajan, Julia; Krier, Irina; Leleu, Marion; Migliavacca, Eugenia; Molina, Nacho; Naldi, Aurélien; Rey, Guillaume; Symul, Laura; Guex, Nicolas; Naef, Felix; Rougemont, Jacques; Bernasconi, David; Delorenzi, Mauro; Andersin, Teemu; Canella, Donatella; Gilardi, Federica; Le Martelot, Gwendal; Lammers, Fabienne; Raghav, Sunil

2012-01-01

The genomic loci occupied by RNA polymerase (RNAP) III have been characterized in human culture cells by genome-wide chromatin immunoprecipitations, followed by deep sequencing (ChIP-seq). These studies have shown that only ∼40% of the annotated 622 human tRNA genes and pseudogenes are occupied by RNAP-III, and that these genes are often in open chromatin regions rich in active RNAP-II transcription units. We have used ChIP-seq to characterize RNAP-III-occupied loci in a differentiated tissue, the mouse liver. Our studies define the mouse liver RNAP-III-occupied loci including a conserved mammalian interspersed repeat (MIR) as a potential regulator of an RNAP-III subunit-encoding gene. They reveal that synteny relationships can be established between a number of human and mouse RNAP-III genes, and that the expression levels of these genes are significantly linked. They establish that variations within the A and B promoter boxes, as well as the strength of the terminator sequence, can strongly affect RNAP-III occupancy of tRNA genes. They reveal correlations with various genomic features that explain the observed variation of 81% of tRNA scores. In mouse liver, loci represented in the NCBI37/mm9 genome assembly that are clearly occupied by RNAP-III comprise 50 Rn5s (5S RNA) genes, 14 known non-tRNA RNAP-III genes, nine Rn4.5s (4.5S RNA) genes, and 29 SINEs. Moreover, out of the 433 annotated tRNA genes, half are occupied by RNAP-III. Transfer RNA gene expression levels reflect both an underlying genomic organization conserved in dividing human culture cells and resting mouse liver cells, and the particular promoter and terminator strengths of individual genes. PMID:22287103

Thermometric studies on the Fe(III)-EDTA chelate.

PubMed

Dot, K

1978-02-01

A DeltaH of -11.5 +/- 0.5 kJ/mole has been determined for the formation of the Fe(III)-EDTA chelate at 25.0 degrees and mu = 0.1(= [HClO(4)] + [NaClO(4)]) by a direct thermometric titration procedure. The entropy change, DeltaS, has been calculated to be 440 J.mole(-1) .deg(-1) by combining the result of the heat measurements with the free energy change obtained from the stability constant previously determined. A relationship between the DeltaS values and the standard partial molal entropies of the tervalent metal ions is discussed. In addition, conditions for the thermometric titration of Fe(III) with NA(4)EDTA at room temperature have been investigated. Iron(III) can be determined in the presence of fairly large amounts of phosphate, Cr(III), Mn(II) and Al(III).

Evolution Reporting in 1925: How the Audience Determined Coverage.

ERIC Educational Resources Information Center

Spencer, Carrie

General interest, scientific, and religious periodicals responded to the theory of evolution in 1925 with the same opinions but slanted their coverage to appeal to different readerships. "Scientific American" and "Current History" differed only stylistically in their coverage of the "Australopithecus africanus"…

Enzymatic versus nonenzymatic mechanisms for Fe(III) reduction in aquatic sediments

USGS Publications Warehouse

Lovley, D.R.; Phillips, E.J.P.; Lonergan, D.J.

1991-01-01

The potential for nonenzymatic reduction of Fe(III) either by organic compounds or by the development of a low redox potential during microbial metabolism was compared with direct, enzymatic Fe(III) reduction by Fe(III)-reducing microorganisms. At circumneutral pH, very few organic compounds nonenzymatically reduced Fe(III). In contrast, in the presence of the appropriate Fe(IH)-reducing microorganisms, most of the organic compounds examined could be completely oxidized to carbon dioxide with the reduction of Fe(III). Even for those organic compounds that could nonenzymatically reduce Fe(III), microbial Fe(III) reduction was much more extensive. The development of a low redox potential during microbial fermentation did not result in nonenzymatic Fe(III) reduction. Model organic compounds were readily oxidized in Fe(III)-reducing aquifer sediments, but not in sterilized sediments. These results suggest that microorganisms enzymatically catalyze most of the Fe(III) reduction in the Fe(III) reduction zone of aquatic sediments and aquifers.

Retrotransposon profiling of RNA polymerase III initiation sites.

PubMed

Qi, Xiaojie; Daily, Kenneth; Nguyen, Kim; Wang, Haoyi; Mayhew, David; Rigor, Paul; Forouzan, Sholeh; Johnston, Mark; Mitra, Robi David; Baldi, Pierre; Sandmeyer, Suzanne

2012-04-01

Although retroviruses are relatively promiscuous in choice of integration sites, retrotransposons can display marked integration specificity. In yeast and slime mold, some retrotransposons are associated with tRNA genes (tDNAs). In the Saccharomyces cerevisiae genome, the long terminal repeat retrotransposon Ty3 is found at RNA polymerase III (Pol III) transcription start sites of tDNAs. Ty1, 2, and 4 elements also cluster in the upstream regions of these genes. To determine the extent to which other Pol III-transcribed genes serve as genomic targets for Ty3, a set of 10,000 Ty3 genomic retrotranspositions were mapped using high-throughput DNA sequencing. Integrations occurred at all known tDNAs, two tDNA relics (iYGR033c and ZOD1), and six non-tDNA, Pol III-transcribed types of genes (RDN5, SNR6, SNR52, RPR1, RNA170, and SCR1). Previous work in vitro demonstrated that the Pol III transcription factor (TF) IIIB is important for Ty3 targeting. However, seven loci that bind the TFIIIB loader, TFIIIC, were not targeted, underscoring the unexplained absence of TFIIIB at those sites. Ty3 integrations also occurred in two open reading frames not previously associated with Pol III transcription, suggesting the existence of a small number of additional sites in the yeast genome that interact with Pol III transcription complexes.

Spectroscopic and Computational Investigation of Iron(III) Cysteine Dioxygenase: Implications for the Nature of the Putative Superoxo-Fe(III) Intermediate

PubMed Central

2015-01-01

Cysteine dioxygenase (CDO) is a mononuclear, non-heme iron-dependent enzyme that converts exogenous cysteine (Cys) to cysteine sulfinic acid using molecular oxygen. Although the complete catalytic mechanism is not yet known, several recent reports presented evidence for an Fe(III)-superoxo reaction intermediate. In this work, we have utilized spectroscopic and computational methods to investigate the as-isolated forms of CDO, as well as Cys-bound Fe(III)CDO, both in the absence and presence of azide (a mimic of superoxide). An analysis of our electronic absorption, magnetic circular dichroism, and electron paramagnetic resonance data of the azide-treated as-isolated forms of CDO within the framework of density functional theory (DFT) computations reveals that azide coordinates directly to the Fe(III), but not the Fe(II) center. An analogous analysis carried out for Cys-Fe(III)CDO provides compelling evidence that at physiological pH, the iron center is six coordinate, with hydroxide occupying the sixth coordination site. Upon incubation of this species with azide, the majority of the active sites retain hydroxide at the iron center. Nonetheless, a modest perturbation of the electronic structure of the Fe(III) center is observed, indicating that azide ions bind near the active site. Additionally, for a small fraction of active sites, azide displaces hydroxide and coordinates directly to the Cys-bound Fe(III) center to generate a low-spin (S = 1/2) Fe(III) complex. In the DFT-optimized structure of this complex, the central nitrogen atom of the azide moiety lies within 3.12 Å of the cysteine sulfur. A similar orientation of the superoxide ligand in the putative Fe(III)-superoxo reaction intermediate would promote the attack of the distal oxygen atom on the sulfur of substrate Cys. PMID:25093959

C III] Emission in Star-forming Galaxies Near and Far

NASA Astrophysics Data System (ADS)

Rigby, J. R.; Bayliss, M. B.; Gladders, M. D.; Sharon, K.; Wuyts, E.; Dahle, H.; Johnson, T.; Peña-Guerrero, M.

2015-11-01

We measure [C iii] 1907, C iii] 1909 Å emission lines in 11 gravitationally lensed star-forming galaxies at z ˜ 1.6-3, finding much lower equivalent widths than previously reported for fainter lensed galaxies. While it is not yet clear what causes some galaxies to be strong C iii] emitters, C iii] emission is not a universal property of distant star-forming galaxies. We also examine C iii] emission in 46 star-forming galaxies in the local universe, using archival spectra from GHRS, FOS, and STIS on HST and IUE. Twenty percent of these local galaxies show strong C iii] emission, with equivalent widths < -5 Å. Three nearby galaxies show C iii] emission equivalent widths as large as the most extreme emitters yet observed in the distant universe; all three are Wolf-Rayet galaxies. At all redshifts, strong C iii] emission may pick out low-metallicity galaxies experiencing intense bursts of star formation. Such local C iii] emitters may shed light on the conditions of star formation in certain extreme high-redshift galaxies.

Cr(III), Fe(III) and Co(III) complexes of tetradentate (ONNO) Schiff base ligands: Synthesis, characterization, properties and biological activity

NASA Astrophysics Data System (ADS)

Keskioğlu, Eren; Gündüzalp, Ayla Balaban; Çete, Servet; Hamurcu, Fatma; Erk, Birgül

2008-08-01

A series of metal complexes were synthesized from equimolar amounts of Schiff bases: 1,4-bis[3-(2-hydroxy-1-naphthaldimine)propyl]piperazine (bappnaf) and 1,8-bis[3-(2-hydroxy-1-naphthaldimine)- p-menthane (damnaf) with metal chlorides. All of synthesized compounds were characterized by elemental analyses, spectral (UV-vis, IR, 1H- 13C NMR, LC-MS) and thermal (TGA-DTA) methods, magnetic and conductance measurements. Schiff base complexes supposed in tetragonal geometry have the general formula [M(bappnaf or damnaf)]Cl· nH 2O, where M = Cr(III), Co(III) and n = 2, 3. But also Fe(III) complexes have octahedral geometry by the coordination of two water molecules and the formula is [Fe(bappnaf or damnaf)(H 2O) 2]Cl. The changes in the selected vibration bands in FT-IR indicate that Schiff bases behave as (ONNO) tetradentate ligands and coordinate to metal ions from two phenolic oxygen atoms and two azomethine nitrogen atoms. Conductance measurements suggest 1:1 electrolytic nature of the metal complexes. The synthesized compounds except bappnaf ligand have the antimicrobial activity against the bacteria: Escherichia coli (ATCC 11230), Yersinia enterocolitica (ATCC 1501), Bacillus magaterium (RSKK 5117), Bacillus subtilis (RSKK 244), Bacillus cereus (RSKK 863) and the fungi: Candida albicans (ATCC 10239). These results have been considerably interest in piperazine derivatives due to their significant applications in antimicrobial studies.

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…

Engineering electron metabolism to increase ethanol production in Clostridium thermocellum.

PubMed

Lo, Jonathan; Olson, Daniel G; Murphy, Sean Jean-Loup; Tian, Liang; Hon, Shuen; Lanahan, Anthony; Guss, Adam M; Lynd, Lee R

2017-01-01

The NfnAB (NADH-dependent reduced ferredoxin: NADP + oxidoreductase) and Rnf (ion-translocating reduced ferredoxin: NAD + oxidoreductase) complexes are thought to catalyze electron transfer between reduced ferredoxin and NAD(P) + . Efficient electron flux is critical for engineering fuel production pathways, but little is known about the relative importance of these enzymes in vivo. In this study we investigate the importance of the NfnAB and Rnf complexes in Clostridium thermocellum for growth on cellobiose and Avicel using gene deletion, enzyme assays, and fermentation product analysis. The NfnAB complex does not seem to play a major role in metabolism, since deletion of nfnAB genes had little effect on the distribution of fermentation products. By contrast, the Rnf complex appears to play an important role in ethanol formation. Deletion of rnf genes resulted in a decrease in ethanol formation. Overexpression of rnf genes resulted in an increase in ethanol production of about 30%, but only in strains where the hydG hydrogenase maturation gene was also deleted. Copyright © 2016 International Metabolic Engineering Society. All rights reserved.

[Cobalt(III)-EDTA] - Reduction by Thermophilic Methanogen Methanothermobacter Thermautotrophicus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singh, Rajesh; Dong, Hailiang; Liu, Deng

2015-06-30

Cobalt is a metal contaminant at high temperature radioactive waste disposal sites. In previous studies have largely focused on mesophilic microorganisms to remediate cobalt, despite the presence of thermophilic microorganisms at such sites. In this study,Methanothermobacter thermautotrophicus, a thermophilic methanogen, was used to reduce Co(III) in the form of [Co(III)–EDTA] -. Bioreduction experiments were conducted in a growth medium with H 2/CO 2 as a growth substrate at initial Co(III) concentrations of 1, 2, 4, 7, and 10 mM. At low Co(III) concentrations (< 4 mM), a complete reduction was observed within a week. Wet chemistry, X-ray absorption near-edge structuremore » (XANES) and electron paramagnetic resonance (EPR) analyses were all consistent in revealing the reduction kinetics. But, at higher concentrations (7 and 10 mM) the reduction extents only reached 69.8% and 48.5%, respectively, likely due to the toxic effect of Co(III) to the methanogen cells as evidenced by a decrease in total cellular protein at these Co(III) concentrations. Methanogenesis was inhibited by Co(III) bioreduction, possibly due to impaired cell growth and electron diversion from CO 2 to Co(III). Overall, our results demonstrated the ability of M. thermautotrophicus to reduce Co(III) to Co(II) and its potential application for remediating 60Co contaminant at high temperature subsurface radioactive waste disposal sites.« less

Earth Science With the Stratospheric Aerosol and Gas Experiment III (SAGE III) on the International Space Station

NASA Technical Reports Server (NTRS)

Zawodny, Joe; Vernier, Jean-Paul; Thomason, Larry; Roell, Marilee; Pitts, Mike; Moore, Randy; Hill, Charles; Flittner, David; Damadeo, Rob; Cisewski, Mike

2015-01-01

The Stratospheric Aerosol and Gas Experiment (SAGE) III is the fourth generation of solar occultation instruments operated by NASA, the first coming under a different acronym, to investigate the Earth's upper atmosphere. Three flight-ready SAGE III instruments were built by Ball Aerospace in the late 1990s, with one launched aboard the former Russian Aviation and Space Agency (now known as Roskosmos) Meteor-3M platform on 10 December 2001 (continuing until the platform lost power in 2006). Another of the original instruments was manifested for the ISS in the 2004 time frame, but was delayed because of budgetary considerations. Fortunately, that SAGE III/ISS mission was restarted in 2009 with a major focus upon filling an anticipated gap in ozone and aerosol observation in the second half of this decade. Here we discuss the mission architecture, its implementation, and data that will be produced by SAGE III/ISS, including their expected accuracy and coverage. The 52-degree inclined orbit of the ISS is well-suited for solar occultation and provides near-global observations on a monthly basis with excellent coverage of low and mid-latitudes. This is similar to that of the SAGE II mission (1985-2005), whose data set has served the international atmospheric science community as a standard for stratospheric ozone and aerosol measurements. The nominal science products include vertical profiles of trace gases, such as ozone, nitrogen dioxide and water vapor, along with multi-wavelength aerosol extinction. Though in the visible portion of the spectrum the brightness of the Sun is one million times that of the full Moon, the SAGE III instrument is designed to cover this large dynamic range and also perform lunar occultations on a routine basis to augment the solar products. The standard lunar products were demonstrated during the SAGE III/M3M mission and include ozone, nitrogen dioxide & nitrogen trioxide. The operational flexibility of the SAGE III spectrometer accomplishes

The Compact Environmental Anomaly Sensor (CEASE) III

NASA Astrophysics Data System (ADS)

Roddy, P.; Hilmer, R. V.; Ballenthin, J.; Lindstrom, C. D.; Barton, D. A.; Ignazio, J. M.; Coombs, J. M.; Johnston, W. R.; Wheelock, A. T.; Quigley, S.

2016-12-01

The Air Force Research Laboratory's Energetic Charged Particle (ECP) sensor project is a comprehensive effort to measure the charged particle environment that causes satellite anomalies. The project includes the Compact Environmental Anomaly Sensor (CEASE) III, building on the flight heritage of prior CEASE designs. CEASE III consists of multiple sensor modules. High energy particles are observed using independent unique silicon detector stacks. In addition CEASE III includes an electrostatic analyzer (ESA) assembly which uses charge multiplication for particle detection. The sensors cover a wide range of proton and electron energies that contribute to satellite anomalies.

40 CFR Appendix III to Part 1068 - High-Altitude Counties

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 33 2011-07-01 2011-07-01 false High-Altitude Counties III Appendix III to Part 1068 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS GENERAL COMPLIANCE PROVISIONS FOR ENGINE PROGRAMS Pt. 1068, App. III Appendix III to Part 1068...

40 CFR Appendix III to Part 1068 - High-Altitude Counties

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 32 2010-07-01 2010-07-01 false High-Altitude Counties III Appendix III to Part 1068 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS GENERAL COMPLIANCE PROVISIONS FOR ENGINE PROGRAMS Pt. 1068, App. III Appendix III to Part 1068...

Vibrational spectra of carboxylato complexes—III. Trinuclear 'basic' acetates and formates of chromium(III), iron(III) and other transition metals

NASA Astrophysics Data System (ADS)

Johnson, M. K.; Powell, D. B.; Cannon, R. D.

The i.r. and Raman spectra of a series of complexes [M III3O(OOCR) 6L 3]X· xH 2O (M = Cr, Fe, Mn, Ru, Rh; L = H 2O, pyridine, γ-picoline; X = Cl, Br, I, NO 3, ClO 3, ClO 4, BF 4) have been analysed in detail. The vibrational modes of the central M 3O and the three surrounding MO 4 units, are identified. The metal—nitrogen stretching vibrations and the MOH 2 modes are assigned. The 'basic' chromium(III) formate is shown to be [Cr 3O(OOCH) 6(OH 2) 2(OOCH)] xH 2O, containing monodentate, inner-sphere coordinated formate ion. The use of the symmetric and asymmetric OCO stretching frequencies in characterizing bridging carboxylate ions is discussed.

As(III) oxidation by MnO2 during groundwater treatment.

PubMed

Gude, J C J; Rietveld, L C; van Halem, D

2017-03-15

The top layer of natural rapid sand filtration was found to effectively oxidise arsenite (As(III)) in groundwater treatment. However, the oxidation pathway has not yet been identified. The aim of this study was to investigate whether naturally formed manganese oxide (MnO 2 ), present on filter grains, could abiotically be responsible for As(III) oxidation in the top of a rapid sand filter. For this purpose As(III) oxidation with two MnO 2 containing powders was investigated in aerobic water containing manganese(II) (Mn(II)), iron(II) (Fe(II)) and/or iron(III) (Fe(III)). The first MnO 2 powder was a very pure - commercially available - natural MnO 2 powder. The second originated from a filter sand coating, produced over 22 years in a rapid filter during aeration and filtration. Jar test experiments showed that both powders oxidised As(III). However, when applying the MnO 2 in aerated, raw groundwater, As(III) removal was not enhanced compared to aeration alone. It was found that the presence of Fe(II)) and Mn(II) inhibited As(III) oxidation, as Fe(II) and Mn(II) adsorption and oxidation were preferred over As(III) on the MnO 2 surface (at pH 7). Therefore it is concluded that just because MnO 2 is present in a filter bed, it does not necessarily mean that MnO 2 will be available to oxidise As(III). However, unlike Fe(II), the addition of Fe(III) did not hinder As(III) oxidation on the MnO 2 surface; resulting in subsequent effective As(V) removal by the flocculating hydrous ferric oxides. Copyright © 2016 Elsevier Ltd. All rights reserved.

Single-molecule magnetism in a family of {Co(III)2Dy(III)2} butterfly complexes: effects of ligand replacement on the dynamics of magnetic relaxation.

PubMed

Langley, Stuart K; Ungur, Liviu; Chilton, Nicholas F; Moubaraki, Boujemaa; Chibotaru, Liviu F; Murray, Keith S

2014-05-05

The synthesis and structural characterization of four related heterometallic complexes of formulas [Dy(III)2Co(III)2(OMe)2(teaH)2(O2CPh)4(MeOH)4](NO3)2·MeOH·H2O (1a) and [Dy(III)2Co(III)2(OMe)2(teaH)2(O2CPh)4(MeOH)2(NO3)2]·MeOH·H2O (1b), [Dy(III)2Co(III)2(OMe)2(dea)2(O2CPh)4(MeOH)4](NO3)2 (2), [Dy(III)2Co(III)2(OMe)2(mdea)2(O2CPh)4(NO3)2] (3), and [Dy(III)2Co(III)2(OMe)2(bdea)2(O2CPh)4(MeOH)4](NO3)2·0.5MeOH·H2O (4a) and [Dy(III)2Co(III)2(OMe)2(bdea)2(O2CPh)4(MeOH)2(NO3)2]·MeOH·1.5H2O (4b) are reported (teaH3 = triethanolamine, deaH2 = diethanolamine, mdeaH2 = N-methyldiethanolamine, and bdeaH2 = N-n-butyldiethanolamine). Compounds 1 (≡ 1a and 1b) and 4 (≡ 4a and 4b) both display two unique molecules within the same crystal and all compounds display a butterfly type core, with the Dy(III) ions occupying the central body positions and the diamagnetic Co(III) ions the outer wing-tip sites. Compounds 1-4 were investigated via direct current and alternating current magnetic susceptibility measurements, and it was found that each complex displayed single-molecule magnet (SMM) behavior. All four compounds display unique coordination and geometric environments around the Dy(III) ions and it was found that each displays a different anisotropy barrier. Ab initio calculations were performed on 1-4 and these determined the low lying electronic structure of each Dy(III) ion and the magnetic interactions for each cluster. It was found that there was a strong correlation between the calculated energy gap between the ground and first excited states of the single-ion ligand-field split Dy(III) levels and the experimentally observed anisotropy barrier. Furthermore, the transverse g factors found for the Dy(III) ions, defining the tunnelling rates within the ground Kramers doublets, are largest for 1, which agrees with the experimental observation of the shortest relaxation time in the high-temperature domain for this complex. The magnetic exchange between the Dy(III

Bayley-III Cognitive and Language Scales in Preterm Children.

PubMed

Spencer-Smith, Megan M; Spittle, Alicia J; Lee, Katherine J; Doyle, Lex W; Anderson, Peter J

2015-05-01

This study aimed to assess the sensitivity and specificity of the Bayley Scales of Infant and Toddler Development, Third Edition (Bayley-III), Cognitive and Language scales at 24 months for predicting cognitive impairments in preterm children at 4 years. Children born <30 weeks' gestation completed the Bayley-III at 24 months and the Differential Ability Scale, Second Edition (DAS-II), at 4 years to assess cognitive functioning. Test norms and local term-born reference data were used to classify delay on the Bayley-III Cognitive and Language scales. Impairment on the DAS-II Global Conceptual Ability, Verbal, and Nonverbal Reasoning indices was classified relative to test norms. Scores < -1 SD relative to the mean were classified as mild/moderate delay or impairment, and scores < -2 SDs were classified as moderate delay or impairment. A total of 105 children completed the Bayley-III and DAS-II. The sensitivity of mild/moderate cognitive delay on the Bayley-III for predicting impairment on DAS-II indices ranged from 29.4% to 38.5% and specificity ranged from 92.3% to 95.5%. The sensitivity of mild/moderate language delay on the Bayley-III for predicting impairment on DAS-II indices ranged from 40% to 46.7% and specificity ranged from 81.1% to 85.7%. The use of local reference data at 24 months to classify delay increased sensitivity but reduced specificity. Receiver operating curve analysis identified optimum cut-point scores for the Bayley-III that were more consistent with using local reference data than Bayley-III normative data. In our cohort of very preterm children, delay on the Bayley-III Cognitive and Language scales was not strongly predictive of future impairments. More children destined for later cognitive impairment were identified by using cut-points based on local reference data than Bayley-III norms. Copyright © 2015 by the American Academy of Pediatrics.

Modular electron-transport chains from eukaryotic organelles function to support nitrogenase activity.

PubMed

Yang, Jianguo; Xie, Xiaqing; Yang, Mingxuan; Dixon, Ray; Wang, Yi-Ping

2017-03-21

A large number of genes are necessary for the biosynthesis and activity of the enzyme nitrogenase to carry out the process of biological nitrogen fixation (BNF), which requires large amounts of ATP and reducing power. The multiplicity of the genes involved, the oxygen sensitivity of nitrogenase, plus the demand for energy and reducing power, are thought to be major obstacles to engineering BNF into cereal crops. Genes required for nitrogen fixation can be considered as three functional modules encoding electron-transport components (ETCs), proteins required for metal cluster biosynthesis, and the "core" nitrogenase apoenzyme, respectively. Among these modules, the ETC is important for the supply of reducing power. In this work, we have used Escherichia coli as a chassis to study the compatibility between molybdenum and the iron-only nitrogenases with ETC modules from target plant organelles, including chloroplasts, root plastids, and mitochondria. We have replaced an ETC module present in diazotrophic bacteria with genes encoding ferredoxin-NADPH oxidoreductases (FNRs) and their cognate ferredoxin counterparts from plant organelles. We observe that the FNR-ferredoxin module from chloroplasts and root plastids can support the activities of both types of nitrogenase. In contrast, an analogous ETC module from mitochondria could not function in electron transfer to nitrogenase. However, this incompatibility could be overcome with hybrid modules comprising mitochondrial NADPH-dependent adrenodoxin oxidoreductase and the Anabaena ferredoxins FdxH or FdxB. We pinpoint endogenous ETCs from plant organelles as power supplies to support nitrogenase for future engineering of diazotrophy in cereal crops.

Studies on the Mechanism of Electron Bifurcation Catalyzed by Electron Transferring Flavoprotein (Etf) and Butyryl-CoA Dehydrogenase (Bcd) of Acidaminococcus fermentans*

PubMed Central

Chowdhury, Nilanjan Pal; Mowafy, Amr M.; Demmer, Julius K.; Upadhyay, Vikrant; Koelzer, Sebastian; Jayamani, Elamparithi; Kahnt, Joerg; Hornung, Marco; Demmer, Ulrike; Ermler, Ulrich; Buckel, Wolfgang

2014-01-01

Electron bifurcation is a fundamental strategy of energy coupling originally discovered in the Q-cycle of many organisms. Recently a flavin-based electron bifurcation has been detected in anaerobes, first in clostridia and later in acetogens and methanogens. It enables anaerobic bacteria and archaea to reduce the low-potential [4Fe-4S] clusters of ferredoxin, which increases the efficiency of the substrate level and electron transport phosphorylations. Here we characterize the bifurcating electron transferring flavoprotein (EtfAf) and butyryl-CoA dehydrogenase (BcdAf) of Acidaminococcus fermentans, which couple the exergonic reduction of crotonyl-CoA to butyryl-CoA to the endergonic reduction of ferredoxin both with NADH. EtfAf contains one FAD (α-FAD) in subunit α and a second FAD (β-FAD) in subunit β. The distance between the two isoalloxazine rings is 18 Å. The EtfAf-NAD+ complex structure revealed β-FAD as acceptor of the hydride of NADH. The formed β-FADH− is considered as the bifurcating electron donor. As a result of a domain movement, α-FAD is able to approach β-FADH− by about 4 Å and to take up one electron yielding a stable anionic semiquinone, α-FAD⨪, which donates this electron further to Dh-FAD of BcdAf after a second domain movement. The remaining non-stabilized neutral semiquinone, β-FADH•, immediately reduces ferredoxin. Repetition of this process affords a second reduced ferredoxin and Dh-FADH− that converts crotonyl-CoA to butyryl-CoA. PMID:24379410

New charge transfer salts based on bis(ethylenedithio)tetrathiafulvalene (ET) and ferro- or antiferromagnetic oxalato-bridged dinuclear anions: syntheses, structures and magnetism of ET5[MM'(C2O4)(NCS)8] with MM' = Cr(III)Fe(III), Cr(III)Cr(III).

PubMed

Triki, S; Bérézovsky, F; Sala Pala, J; Gómez-García, C J; Coronado, E; Costuas, K; Halet, J F

2001-09-24

Electrochemical combination of the magnetic dinuclear anion [MM'(C2O4)(NCS)8](4-) (MM' = Cr(III)Cr(III), Cr(III)Fe(III)) with the ET organic pi-donor (ET = BEDT-TTF = bis(ethylenedithio)tetrathiafulvalene) gives rise to two new isostructural molecular hybrid salts ET5[MM'(C2O4)(NCS)8], with MM' = CrCr (1), CrFe (2). The molecular structure of compound 1 has been determined by single crystal X-ray diffraction. The particular arrangement of the organic units consists of an unprecedented two-dimensional organic sublattice nearly similar to that observed in kappa-phase structures. For both compounds, the magnetic susceptibility measurements indicate (i) the ET radicals do not contribute to the magnetic moment probably due to the presence of strong antiferromagnetic interaction between them, and (ii) in the anion, the magnetic coupling is antiferromagnetic for 1 (J = -3.65 cm(-1)) and ferromagnetic for 2 (J = 1.14 cm(-1), J being the parameter of the exchange Hamiltonian H = -2JS1S2). The field dependence of the magnetization of compound 2 at 2.0 K gives further evidence of the S = 4 ground-state arising from the interaction between S = 3/2 Cr(III) and S = 5/2 Fe(III). EPR measurements confirm the nature of the magnetic interactions and the absence of any contribution from the organic part, as observed from the static magnetic measurement. Conductivity measurements and electronic band structure calculations show that both salts are semiconductors with low activation energies.

Antithrombin III in animal models of sepsis and organ failure.

PubMed

Dickneite, G

1998-01-01

Antithrombin III (AT III) is the physiological inhibitor of thrombin and other serine proteases of the clotting cascade. In the development of sepsis, septic shock and organ failure, the plasma levels of AT III decrease considerably, suggesting the concept of a substitution therapy with the inhibitor. A decrease of AT III plasma levels might also be associated with other pathological disorders like trauma, burns, pancreatitis or preclampsia. Activation of coagulation and consumption of AT III is the consequence of a generalized inflammation called SIRS (systemic inflammatory response syndrome). The clotting cascade is also frequently activated after organ transplantation, especially if organs are grafted between different species (xenotransplantation). During the past years AT III has been investigated in numerous corresponding disease models in different animal species which will be reviewed here. The bulk of evidence suggests, that AT III substitution reduces morbidity and mortality in the diseased animals. While gaining more experience with AT III, the concept of substitution therapy to maximal baseline plasma levels (100%) appears to become insufficient. Evidence from clinical and preclinical studies now suggests to adjust the AT III plasma levels to about 200%, i.e., doubling the normal value. During the last few years several authors proposed that AT III might not only be an anti-thrombotic agent, but to have in addition an anti-inflammatory effect.

III-V aresenide-nitride semiconductor materials and devices

NASA Technical Reports Server (NTRS)

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

1997-01-01

III-V arsenide-nitride semiconductor crystals, methods for producing such crystals and devices employing such crystals. 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 crystals 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 crystals can be accomplished by growing thin layers of elements or compounds in sequences that result in the overall lattice match and bandgap desired.

SAGE III on the International Space Station

NASA Astrophysics Data System (ADS)

McCormick, M. P.; Damadeo, R. P.; Hill, C. A.

2017-12-01

A much-improved Stratospheric Aerosol and Gas Experiment (SAGE III) instrument was launched on February 19, 2017 from NASA's Kennedy Space Center aboard the SpaceX CRS-10 Dragon Spacecraft. It subsequently docked with the International Space Station (ISS), completed commissioning on July 1, 2017, and is now in its Mission Operations phase. SAGE III-ISS will combine the experience and capabilities of its successful predecessor satellite instruments SAM II, SAGE, SAGE II, and SAGE III-Meteor-3M to measure aerosol, cloud, O3, H2O, and NO2 profiles from the upper troposphere through the stratosphere. In addition to solar and lunar occultation with vertical resolutions of about 1.0 km, SAGE III-ISS will make limb scattering measurements on the solar side of each orbit greatly expanding the measurement coverage per spacecraft orbit, and tie the very high resolution and precise solar occultation measurements with the limb scattering measurements. The programmable readout array detector enhances its measurement capability and should allow for experimental data products like BrO, and IO, and along with a single photodiode detector, the measurement of larger aerosols. The wavelengths covered by SAGE III-ISS range from 280 to 1050 nm with 1 to 2 nm spectral resolution using a grating spectrometer. The single photodiode extends measurements to 1550 nm. This talk will describe the measurement capabilities of SAGE III, and include early data and validation examples, its additional modes and increased geographical coverage, its calibration and characterization, and data archival and validation approach.

Non-surgical treatment of skeletal class III malocclusion

PubMed Central

Kapadia, Romina M; Shah, Adit P; Diyora, Shamil D; Rathva, Vandana J

2014-01-01

The incidence of skeletal class III malocclusion has a mean of 3% in the Caucasian population, 5% in African-American adolescents and about 14% in the Asian population. In India, the incidence of class III malocclusion is reported to be 3.4%. A patient having class III malocclusion shows findings ranging from edge-to-edge bite to large reverse overjet, with extreme variations of underlying skeletal jaw bases and craniofacial form. This is a case report of a 20-year-old man having skeletal class III malocclusion with concave profile, anterior crossbite and a negative overjet of 3 mm treated non-surgically with extraction of only one lower left first premolar. PMID:24722711

C III] Emission in Star-Forming Galaxies Near and Far

NASA Technical Reports Server (NTRS)

Rigby, J, R.; Bayliss, M. B.; Gladders, M. D.; Sharon, K.; Wuyts, E.; Dahle, H.; Johnson, T.; Pena-Guerrero, M.

2015-01-01

We measure C III Lambda Lambda 1907, 1909 Angstrom emission lines in eleven gravitationally-lensed star-forming galaxies at zeta at approximately 1.6-3, finding much lower equivalent widths than previously reported for fainter lensed galaxies (Stark et al. 2014). While it is not yet clear what causes some galaxies to be strong C III] emitters, C III] emission is not a universal property of distant star-forming galaxies. We also examine C III] emission in 46 star-forming galaxies in the local universe, using archival spectra from GHRS, FOS, and STIS on HST, and IUE. Twenty percent of these local galaxies show strong C III] emission, with equivalent widths less than -5 Angstrom. Three nearby galaxies show C III] emission equivalent widths as large as the most extreme emitters yet observed in the distant universe; all three are Wolf-Rayet galaxies. At all redshifts, strong C III] emission may pick out low-metallicity galaxies experiencing intense bursts of star formation. Such local C III] emitters may shed light on the conditions of star formation in certain extreme high-redshift galaxies.

Evaluation of [(201)Tl](III) Vancomycin in normal rats.

PubMed

Jalilian, Amir Reza; Hosseini, Mohammad Amin; Majdabadi, Abbas; Saddadi, Fariba

2008-01-01

Tl-201 has potential in the preparation of radiolabelled compounds similar to its homologues, like In-111 and radiogallium. In this paper, recently prepared [(201)Tl](III) vancomycin complex ([(201)Tl](III)VAN) has been evaluated for its biological properties. [(201)Tl](III)VAN was prepared according to the optimized conditions followed by biodistribution studies in normal rats for up to 52 h. The Staphylococcus aurous specific binding was checked in vitro. The complex was finally injected to normal rats. Tracer SPECT images were obtained in normal animals and compared to those of (67)Ga-citrate. Freshly-prepared [(201)Tl](III)VAN batches (radiochemical yield > 99%, radiochemical purity > 98%, specific activity approximately 1.2 Ci/mmol) showed a similar biodistribution to that of unlabeled vancomycin. The microorganism binding ratios were 3 and 9 for tracer (201)Tl(3+) and tracer (201)Tl(III)DTPA, respectively, suggesting the preservation of the tracer bioactivity. As a nonspecific cell penetrating tracer, [(201)Tl](III)DTPA was used.

Pentanuclear heterometallic {Mn(III)(2)Ln(3)} (Ln = Gd, Dy, Tb, Ho) assemblies in an open-book type structural topology: appearance of slow relaxation of magnetization in the Dy(III) and Ho(III) analogues.

PubMed

Bag, Prasenjit; Chakraborty, Amit; Rogez, Guillaume; Chandrasekhar, Vadapalli

2014-07-07

The reaction of Ln(III) nitrate and Mn(ClO4)2·6H2O salts in the presence of a multidentate sterically unencumbered ligand, (E)-2,2'-(2-hydroxy-3-((2-hydroxyphenylimino)methyl)-5-methylbenzylazanediyl)diethanol (LH4) leads to the isolation of four isostructural pentanuclear hetereometallic complexes [Mn(III)2Gd3(LH)4(NO3)(HOCH3)]ClO4·NO3 (1), [Mn(III)2Dy3(LH)4(NO3)(HOCH3)]ClO4·NO3 (2), [Mn(III)2Tb3(LH)4(NO3)(HOCH3)]ClO4·NO3 (3), and [Mn(III)2Ho3(LH)4(NO3)(HOCH3)]ClO4·NO3 (4) with an open-book type structural topology. 1-4 are dicationic and crystallize in the achiral space group, P21/n. A total of four triply deprotonated ligands, [LH](3-), are involved in holding the pentameric metal framework, {Mn(III)2Ln3}. In these complexes both the lanthanide and the manganese(III) ions are doubly bridged, involving phenolate or ethoxide oxygen atoms. The magnetochemical analysis reveals the presence of global antiferromagnetic interactions among the spin centers at low temperatures in all the four compounds. AC susceptibility measurements show the presence of temperature dependent out-of-phase ac signal for compounds 2 and 4 indicating an SMM behavior.

Reactions of a Chromium(III)-Superoxo Complex and Nitric Oxide That Lead to the Formation of Chromium(IV)-Oxo and Chromium(III)-Nitrito Complexes

PubMed Central

Yokoyama, Atsutoshi; Cho, Kyung-Bin

2013-01-01

The reaction of an end-on Cr(III)-superoxo complex bearing a 14-membered tetraazamacrocyclic TMC ligand, [CrIII(14-TMC)(O2)(Cl)]+, with nitric oxide (NO) resulted in the generation of a stable Cr(IV)-oxo species, [CrIV(14-TMC)(O)(Cl)]+, via the formation of a Cr(III)-peroxynitrite intermediate and homolytic O-O bond cleavage of the peroxynitrite ligand. Evidence for the latter comes from EPR spectroscopy, computational chemistry, and the observation of phenol nitration chemistry. The Cr(IV)-oxo complex does not react with nitrogen dioxide (NO2), but reacts with NO to afford a Cr(III)-nitrito complex, [CrIII(14-TMC)(NO2)(Cl)]+. The Cr(IV)-oxo and Cr(III)-nitrito complexes were also characterized spectroscopically and/or structurally. PMID:24066924

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

Oxidation of Cr(III)-Fe(III) Mixed-phase Hydroxides by Chlorine: Implications on the Control of Hexavalent Chromium in Drinking Water.

PubMed

Chebeir, Michelle; Liu, Haizhou

2018-05-17

The occurrence of chromium (Cr) as an inorganic contaminant in drinking water is widely reported. One source of Cr is its accumulation in iron-containing corrosion scales of drinking water distribution systems as Cr(III)-Fe(III) hydroxide, i.e., FexCr(1-x)(OH)3(s), where x represents the Fe(III) molar content and typically varies between 0.25 and 0.75. This study investigated the kinetics of inadvertent hexavalent chromium Cr(VI) formation via the oxidation of FexCr(1-x)(OH)3(s) by chlorine as a residual disinfectant in drinking water, and examined the impacts of Fe(III) content and drinking water chemical parameters including pH, bromide and bicarbonate on the rate of Cr(VI) formation. Data showed that an increase in Fe(III) molar content resulted in a significant decrease in the stoichiometric Cr(VI) yield and the rate of Cr(VI) formation, mainly due to chlorine decay induced by Fe(III) surface sites. An increase in bicarbonate enhanced the rate of Cr(VI) formation, likely due to the formation of Fe(III)-carbonato surface complexes that slowed down the scavenging reaction with chlorine. The presence of bromide significantly accelerated the oxidation of FexCr(1-x)(OH)3(s) by chlorine, resulting from the catalytic effect of bromide acting as an electron shuttle. A higher solution pH between 6 and 8.5 slowed down the oxidation of Cr(III) by chlorine. These findings suggested that the oxidative conversion of chromium-containing iron corrosion products in drinking water distribution systems can lead to the occurrence of Cr(VI) at the tap, and the abundance of iron, and a careful control of pH, bicarbonate and bromide levels can assist the control of Cr(VI) formation.

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...

Energy Conservation Associated with Ethanol Formation from H2 and CO2 in Clostridium autoethanogenum Involving Electron Bifurcation

PubMed Central

Mock, Johanna; Zheng, Yanning; Mueller, Alexander P.; Ly, San; Tran, Loan; Segovia, Simon; Nagaraju, Shilpa; Köpke, Michael; Dürre, Peter

2015-01-01

ABSTRACT Most acetogens can reduce CO2 with H2 to acetic acid via the Wood-Ljungdahl pathway, in which the ATP required for formate activation is regenerated in the acetate kinase reaction. However, a few acetogens, such as Clostridium autoethanogenum, Clostridium ljungdahlii, and Clostridium ragsdalei, also form large amounts of ethanol from CO2 and H2. How these anaerobes with a growth pH optimum near 5 conserve energy has remained elusive. We investigated this question by determining the specific activities and cofactor specificities of all relevant oxidoreductases in cell extracts of H2/CO2-grown C. autoethanogenum. The activity studies were backed up by transcriptional and mutational analyses. Most notably, despite the presence of six hydrogenase systems of various types encoded in the genome, the cells appear to contain only one active hydrogenase. The active [FeFe]-hydrogenase is electron bifurcating, with ferredoxin and NADP as the two electron acceptors. Consistently, most of the other active oxidoreductases rely on either reduced ferredoxin and/or NADPH as the electron donor. An exception is ethanol dehydrogenase, which was found to be NAD specific. Methylenetetrahydrofolate reductase activity could only be demonstrated with artificial electron donors. Key to the understanding of this energy metabolism is the presence of membrane-associated reduced ferredoxin:NAD+ oxidoreductase (Rnf), of electron-bifurcating and ferredoxin-dependent transhydrogenase (Nfn), and of acetaldehyde:ferredoxin oxidoreductase, which is present with very high specific activities in H2/CO2-grown cells. Based on these findings and on thermodynamic considerations, we propose metabolic schemes that allow, depending on the H2 partial pressure, the chemiosmotic synthesis of 0.14 to 1.5 mol ATP per mol ethanol synthesized from CO2 and H2. IMPORTANCE Ethanol formation from syngas (H2, CO, and CO2) and from H2 and CO2 that is catalyzed by bacteria is presently a much-discussed process for

Photoinduced oxidation of a water-soluble manganese(III) porphyrin

PubMed Central

Maliyackel, Anthony C.; Otvos, John W.; Spreer, Larry O.; Calvin, Melvin

1986-01-01

The photoinduced oxidation of tetra(N-methyl-4-pyridyl)porphyrinmanganese(III) has been achieved in homogeneous solution. The manganese porphyrin was used as an electron donor in a three-component system with tris-(2,2′-bipyridine)ruthenium(II) as the photosensitizer and chloropentaamminecobalt(III) as the electron acceptor. The photooxidized manganese porphyrin is unstable in aqueous solution, reverting to the starting manganese(III) porphyrin. The oxidation of manganese(III) porphyrin and the subsequent reduction of the oxidized porphyrin can be cycled repeatedly. PMID:16593699

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.

Phylogenetic analysis of dissimilatory Fe(III)-reducing bacteria

USGS Publications Warehouse

Lonergan, D.J.; Jenter, H.L.; Coates, J.D.; Phillips, E.J.P.; Schmidt, T.M.; Lovley, D.R.

1996-01-01

Evolutionary relationships among strictly anaerobic dissimilatory Fe(III)- reducing bacteria obtained from a diversity of sedimentary environments were examined by phylogenetic analysis of 16S rRNA gene sequences. Members of the genera Geobacter, Desulfuromonas, Pelobacter, and Desulfuromusa formed a monophyletic group within the delta subdivision of the class Proteobacteria. On the basis of their common ancestry and the shared ability to reduce Fe(III) and/or S0, we propose that this group be considered a single family, Geobacteraceae. Bootstrap analysis, characteristic nucleotides, and higher- order secondary structures support the division of Geobacteraceae into two subgroups, designated the Geobacter and Desulfuromonas clusters. The genus Desulfuromusa and Pelobacter acidigallici make up a distinct branch with the Desulfuromonas cluster. Several members of the family Geobacteraceae, none of which reduce sulfate, were found to contain the target sequences of probes that have been previously used to define the distribution of sulfate-reducing bacteria and sulfate-reducing bacterium-like microorganisms. The recent isolations of Fe(III)-reducing microorganisms distributed throughout the domain Bacteria suggest that development of 16S rRNA probes that would specifically target all Fe(III) reducers may not be feasible. However, all of the evidence suggests that if a 16S rRNA sequence falls within the family Geobacteraceae, then the organism has the capacity for Fe(III) reduction. The suggestion, based on geological evidence, that Fe(III) reduction was the first globally significant process for oxidizing organic matter back to carbon dioxide is consistent with the finding that acetate-oxidizing Fe(III) reducers are phylogenetically diverse.

Characterization of a heterobimetallic nonheme Fe(III)-O-Cr(III) species formed by O2 activation.

PubMed

Zhou, Ang; Kleespies, Scott T; Van Heuvelen, Katherine M; Que, Lawrence

2015-10-01

We report the generation and spectroscopic characterization of a heterobimetallic [(TMC)Fe(III)-O-Cr(III)(OTf)4] species (1) by bubbling O2 into a mixture of Fe(TMC)(OTf)2 and Cr(OTf)2 in NCCH3. Complex 1 also formed quantitatively by adding Cr(OTf)2 to [Fe(IV)(O)(TMC)(NCCH3)](2+). The proposed O2 activation mechanism involves the trapping of a Cr-O2 adduct by Fe(TMC)(OTf)2.

Characterization of a Heterobimetallic Nonheme Fe(III)-O-Cr(III) Species Formed by O2 Activation

PubMed Central

Zhou, Ang; Kleespies, Scott T.; Van Heuvelen, Katherine M.; Que, Lawrence

2015-01-01

We report the generation and spectroscopic characterization of a heterobimetallic [(TMC)FeIII-O-CrIII(OTf)4] species (1) by O2 bubbling into a mixture of Fe(TMC)(OTf)2 and Cr(OTf)2 in NCCH3. Complex 1 also formed quantitatively by adding Cr(OTf)2 to [FeIV(O)(TMC)(NCCH3)]2+. The proposed O2 activation mechanism involves the trapping by a Cr-O2 adduct by Fe(TMC)(OTf)2. PMID:26265081

32 CFR 2003.3 - Functions (Article III).

Code of Federal Regulations, 2014 CFR

2014-07-01

... 32 National Defense 6 2014-07-01 2014-07-01 false Functions (Article III). 2003.3 Section 2003.3 National Defense Other Regulations Relating to National Defense INFORMATION SECURITY OVERSIGHT OFFICE...) BYLAWS, RULES, AND APPEAL PROCEDURES Bylaws § 2003.3 Functions (Article III). In carrying out its purpose...

32 CFR 2003.3 - Functions (Article III).

Code of Federal Regulations, 2013 CFR

2013-07-01

... 32 National Defense 6 2013-07-01 2013-07-01 false Functions (Article III). 2003.3 Section 2003.3 National Defense Other Regulations Relating to National Defense INFORMATION SECURITY OVERSIGHT OFFICE...) BYLAWS, RULES, AND APPEAL PROCEDURES Bylaws § 2003.3 Functions (Article III). In carrying out its purpose...

FATE OF CHROMIUM (III) IN CHLORINATED WATER

EPA Science Inventory

The oxidation of trivalent chromium, Cr(III), to the more toxic Cr(VI) in chlorinated water is thermodynamically feasible and was the subject of the study. The study found that free available chlorine (FAC) readily converts Cr(III) to Cr(VI) at a rate that is highly dependent upo...

21 CFR 864.7060 - Antithrombin III assay.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Antithrombin III assay. 864.7060 Section 864.7060 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Hematology Kits and Packages § 864.7060 Antithrombin III...

21 CFR 864.7060 - Antithrombin III assay.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Antithrombin III assay. 864.7060 Section 864.7060 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Hematology Kits and Packages § 864.7060 Antithrombin III...

21 CFR 864.7060 - Antithrombin III assay.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Antithrombin III assay. 864.7060 Section 864.7060 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Hematology Kits and Packages § 864.7060 Antithrombin III...

21 CFR 864.7060 - Antithrombin III assay.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Antithrombin III assay. 864.7060 Section 864.7060 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Hematology Kits and Packages § 864.7060 Antithrombin III...

21 CFR 864.7060 - Antithrombin III assay.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Antithrombin III assay. 864.7060 Section 864.7060 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Hematology Kits and Packages § 864.7060 Antithrombin III...

Improving Hybrid III injury assessment in steering wheel rim to chest impacts using responses from finite element Hybrid III and human body model.

PubMed

Holmqvist, Kristian; Davidsson, Johan; Mendoza-Vazquez, Manuel; Rundberget, Peter; Svensson, Mats Y; Thorn, Stefan; Törnvall, Fredrik

2014-01-01

The main aim of this study was to improve the quality of injury risk assessments in steering wheel rim to chest impacts when using the Hybrid III crash test dummy in frontal heavy goods vehicle (HGV) collision tests. Correction factors for chest injury criteria were calculated as the model chest injury parameter ratios between finite element (FE) Hybrid III, evaluated in relevant load cases, and the Total Human Model for Safety (THUMS). This is proposed to be used to compensate Hybrid III measurements in crash tests where steering wheel rim to chest impacts occur. The study was conducted in an FE environment using an FE-Hybrid III model and the THUMS. Two impactor shapes were used, a circular hub and a long, thin horizontal bar. Chest impacts at velocities ranging from 3.0 to 6.0 m/s were simulated at 3 impact height levels. A ratio between FE-Hybrid III and THUMS chest injury parameters, maximum chest compression C max, and maximum viscous criterion VC max, were calculated for the different chest impact conditions to form a set of correction factors. The definition of the correction factor is based on the assumption that the response from a circular hub impact to the middle of the chest is well characterized and that injury risk measures are independent of impact height. The current limits for these chest injury criteria were used as a basis to develop correction factors that compensate for the limitations in biofidelity of the Hybrid III in steering wheel rim to chest impacts. The hub and bar impactors produced considerably higher C max and VC max responses in the THUMS compared to the FE-Hybrid III. The correction factor for the responses of the FE-Hybrid III showed that the criteria responses for the bar impactor were consistently overestimated. Ratios based on Hybrid III and THUMS responses provided correction factors for the Hybrid III responses ranging from 0.84 to 0.93. These factors can be used to estimate C max and VC max values when the Hybrid III is

25 CFR 522.12 - Revocation of class III gaming.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 25 Indians 2 2010-04-01 2010-04-01 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 III...

Application of new WAIS-III/WMS-III discrepancy scores for evaluating memory functioning: relationship between intellectual and memory ability.

PubMed

Lange, Rael T; Chelune, Gordon J

2006-05-01

Analysis of the discrepancy between memory and intellectual ability has received some support as a means for evaluating memory impairment. Recently, comprehensive base rate tables for General Ability Index (GAI) minus memory discrepancy scores (i.e., GAI-memory) were developed using the WAIS-III/WMS-III standardization sample (Lange, Chelune, & Tulsky, in press). The purpose of this study was to evaluate the clinical utility of GAI-memory discrepancy scores to identify memory impairment in 34 patients with Alzheimer's type dementia (DAT) versus a sample of 34 demographically matched healthy participants. On average, patients with DAT obtained significantly lower scores on all WAIS-III and WMS-III indexes and had larger GAI-memory discrepancy scores. Clinical outcome analyses revealed that GAI-memory scores were useful at identifying memory impairment in patients with DAT versus matched healthy participants. However, GAI-memory discrepancy scores failed to provide unique interpretive information beyond that which is gained from the memory indexes alone. Implications and future research directions are discussed.

Validation of Resource Utilization Groups version III for Home Care (RUG-III/HC): evidence from a Canadian home care jurisdiction.

PubMed

Poss, Jeffrey W; Hirdes, John P; Fries, Brant E; McKillop, Ian; Chase, Mary

2008-04-01

The case-mix system Resource Utilization Groups version III for Home Care (RUG-III/HC) was derived using a modest data sample from Michigan, but to date no comprehensive large scale validation has been done. This work examines the performance of the RUG-III/HC classification using a large sample from Ontario, Canada. Cost episodes over a 13-week period were aggregated from individual level client billing records and matched to assessment information collected using the Resident Assessment Instrument for Home Care, from which classification rules for RUG-III/HC are drawn. The dependent variable, service cost, was constructed using formal services plus informal care valued at approximately one-half that of a replacement worker. An analytic dataset of 29,921 episodes showed a skewed distribution with over 56% of cases falling into the lowest hierarchical level, reduced physical functions. Case-mix index values for formal and informal cost showed very close similarities to those found in the Michigan derivation. Explained variance for a function of combined formal and informal cost was 37.3% (20.5% for formal cost alone), with personal support services as well as informal care showing the strongest fit to the RUG-III/HC classification. RUG-III/HC validates well compared with the Michigan derivation work. Potential enhancements to the present classification should consider the large numbers of undifferentiated cases in the reduced physical function group, and the low explained variance for professional disciplines.

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…

Dissimilatory Fe(III) reduction by the marine microorganism Desulfuromonas acetoxidans

USGS Publications Warehouse

Roden, E.E.; Lovley, D.R.

1993-01-01

The ability of the marine microorganism Desulfuromonas acetoxidans to reduce Fe(III) was investigated because of its close phylogenetic relationship with the freshwater dissimilatory Fe(III) reducer Geobacter metallireducens. Washed cell suspensions of the type strain of D. acetoxidans reduced soluble Fe(III)-citrate and Fe(III) complexed with nitriloacetic acid. The c-type cytochrome(s) of D. acetoxidans was oxidized by Fe(III)- citrate and Mn(IV)-oxalate, as well as by two electron acceptors known to support growth, colloidal sulfur and malate. D. acetoxidans grew in defined anoxic, bicarbonate-buffered medium with acetate as the sole electron donor and poorly crystalline Fe(III) or Mn(IV) as the sole electron acceptor. Magnetite (Fe3O4) and siderite (FeCO3) were the major end products of Fe(III) reduction, whereas rhodochrosite (MnCO3) was the end product of Mn(IV) reduction. Ethanol, propanol, pyruvate, and butanol also served as electron donors for Fe(III) reduction. In contrast to D. acetoxidans, G. metallireducens could only grow in freshwater medium and it did not conserve energy to support growth from colloidal S0 reduction. D. acetoxidans is the first marine microorganism shown to conserve energy to support growth by coupling the complete oxidation of organic compounds to the reduction of Fe(III) or Mn(IV). Thus, D. acetoxidans provides a model enzymatic mechanism for Fe(III) or Mn(IV) oxidation of organic compounds in marine and estuarine sediments. These findings demonstrate that 16S rRNA phylogenetic analyses can suggest previously unrecognized metabolic capabilities of microorganisms.

Chemical Properties And Toxicity of Chromium(III) Nutritional Supplements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Levina, A.; Lay, P.A.

2009-05-19

The status of Cr(III) as an essential micronutrient for humans is currently under question. No functional Cr(III)-containing biomolecules have been definitively described as yet, and accumulated experience in the use of Cr(III) nutritional supplements (such as [Cr(pic){sub 3}], where pic = 2-pyridinecarboxylato) has shown no measurable benefits for nondiabetic people. Although the use of large doses of Cr(III) supplements may lead to improvements in glucose metabolism for type 2 diabetics, there is a growing concern over the possible genotoxicity of these compounds, particularly of [Cr(pic){sub 3}]. The current perspective discusses chemical transformations of Cr(III) nutritional supplements in biological media, withmore » implications for both beneficial and toxic actions of Cr(III) complexes, which are likely to arise from the same biochemical mechanisms, dependent on concentrations of the reactive species. These species include: (1) partial hydrolysis products of Cr(III) nutritional supplements, which are capable of binding to biological macromolecules and altering their functions; and (2) highly reactive Cr(VI/V/IV) species and organic radicals, formed in reactions of Cr(III) with biological oxidants. Low concentrations of these species are likely to cause alterations in cell signaling (including enhancement of insulin signaling) through interactions with the active centers of regulatory enzymes in the cell membrane or in the cytoplasm, while higher concentrations are likely to produce genotoxic DNA lesions in the cell nucleus. These data suggest that the potential for genotoxic side-effects of Cr(III) complexes may outweigh their possible benefits as insulin enhancers, and that recommendations for their use as either nutritional supplements or antidiabetic drugs need to be reconsidered in light of these recent findings.« less

Solubility and transport of Cr(III) in a historically contaminated soil - Evidence of a rapidly reacting dimeric Cr(III) organic matter complex.

PubMed

Löv, Åsa; Sjöstedt, Carin; Larsbo, Mats; Persson, Ingmar; Gustafsson, Jon Petter; Cornelis, Geert; Kleja, Dan B

2017-12-01

Chromium is a common soil contaminant and, although it has been studied widely, questions about its speciation and dissolutions kinetics remain unanswered. We combined information from an irrigation experiment performed with intact soil columns with data from batch experiments to evaluate solubility and mobilization mechanisms of Cr(III) in a historically contaminated soil (>65 years). Particulate and colloidal Cr(III) forms dominated transport in this soil, but their concentrations were independent of irrigation intensity (2-20 mm h -1 ). Extended X-ray absorption fine structure (EXAFS) measurements indicated that Cr(III) associated with colloids and particles, and with the solid phase, mainly existed as dimeric hydrolyzed Cr(III) bound to natural organic matter. Dissolution kinetics of this species were fast (≤1 day) at low pH (<3) and slightly slower (≤5 days) at neutral pH. Furthermore, it proved possible to describe the solubility of the dimeric Cr(III) organic matter complex with a geochemical equilibrium model using only generic binding parameters, opening the way for use of geochemical models in risk assessments of Cr(III)-contaminated sites. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Applying RUG-III in Japanese Long-Term Care Facilities.

ERIC Educational Resources Information Center

Ikegami, Naoki; And Others

1994-01-01

Tested U.S. nursing home case-mix system, Resource Utilization Groups, Version III (RUG-III) in Japanese long-term care facilities. Measured staff time and resident characteristics for 871 patients. Found acceptable reliability for items defining RUG-III, and system explained 44% of variance in wage-weighted staff time (cost). Japanese and U.S.…

FIRE III ACE

Atmospheric Science Data Center

2013-01-23

FIRE III ACE Data Sets The First International Satellite Cloud ... Regional Experiment (FIRE) - Arctic Cloud Experiment (ACE) was conducted April through July of 1998. It was held in conjunction with ... Heat Budget of the Arctic Ocean (SHEBA) Experiment. The FIRE-ACE focused on all aspects of Arctic cloud systems. The main facility was ...

Strongly Circularly Polarized Emission from Water-Soluble Eu(III)- and Tb(III)-Based Complexes: A Structural and Spectroscopic Study.

PubMed

Leonzio, Marco; Melchior, Andrea; Faura, Georgina; Tolazzi, Marilena; Zinna, Francesco; Di Bari, Lorenzo; Piccinelli, Fabio

2017-04-17

Water-soluble Eu(III) and Tb(III) complexes with N,N'-bis(2-pyridylmethyl)-trans-1,2-diaminocyclohexane-N,N'-diacetic acid (H 2 bpcd) have been synthesized and characterized in their racemic and enantiopure forms. The ligand has been designed to bind Ln(III) ions, providing a dissymmetric environment able to solicit strong chiroptical features while at the same time leaving a few coordination sites available for engaging further ancillary ligands. Potentiometric studies show that Ln(III) complexes have a relatively good stability and that at pH 7 the [Ln(bpcd)] + species is largely dominant. DFT calculations carried out on the (S,S)-[Y(bpcd)(H 2 O) 5 ] + complexes (the closed-shell equivalents of [Eu(bpcd)(H 2 O) 5 ] + and [Tb(bpcd)(H 2 O) 5 ] + ) indicate that the two trans-O,O and trans-N py ,N py configurations are equally stable in solution and present two coordinated water molecules. This is in agreement with the hydration number ∼2.6 determined by luminescence lifetime measurements on Tb(III) and Eu(III) complexes. A detailed optical and chiroptical spectroscopic characterization has been carried out and reveals that the complexes display an efficient luminescence in the visible spectral range accompanied by a strong CPL activity. A value for g lum (around 0.1 on the top of the 546 nm band) for the Tb-based complex has been found. This is one of the highest g lum values measured up to now for chiral Tb complexes. These results suggest that in principle Tb(bpcd)Cl is suitable to be employed as a CPL bioprobe for relevant analytes in aqueous media.

Use of scanning electron microscopy to confirm the identity of lice infesting communally grazed goat herds.

PubMed

Sebei, P J; McCrindle, C M E; Green, E D; Turner, M L

2004-06-01

Lice have been described on goats in commercial farming systems in South Africa but not from flocks on communal grazing. During a longitudinal survey on the causes of goat kid mortality, conducted in Jericho district, North West Province, lice were collected from communally grazed indigenous goats. These lice were prepared for and viewed by scanning electron microscopy, and micro-morphological taxonomic details are described. Three species of lice were found in the study area and identified as Bovicola caprae, Bovicola limbatus and Linognathus africanus. Sucking and biting lice were found in ten of the 12 herds of goats examined. Lice were found on both mature goats and kids. Bovicola caprae and L. africanus were the most common biting and sucking lice respectively in all herds examined. Scanning electron microscopy revealed additional features which aided in the identification of the louse species. Photomicrographs were more accurate aids to identification than the line drawings in the literature and facilitated identification using dissecting microscope.

Methods for fabricating thin film III-V compound solar cell

DOEpatents

Pan, Noren; Hillier, Glen; Vu, Duy Phach; Tatavarti, Rao; Youtsey, Christopher; McCallum, David; Martin, Genevieve

2011-08-09

The present invention utilizes epitaxial lift-off in which a sacrificial layer is included in the epitaxial growth between the substrate and a thin film III-V compound solar cell. To provide support for the thin film III-V compound solar cell in absence of the substrate, a backing layer is applied to a surface of the thin film III-V compound solar cell before it is separated from the substrate. To separate the thin film III-V compound solar cell from the substrate, the sacrificial layer is removed as part of the epitaxial lift-off. Once the substrate is separated from the thin film III-V compound solar cell, the substrate may then be reused in the formation of another thin film III-V compound solar cell.

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…

Luminescent Properties of Eu(III) Chelates on Metal Nanorods

PubMed Central

Zhang, Jian; Fu, Yi; Ray, Krishanu; Wang, Yuan; Lakowicz, Joseph. R.

2013-01-01

In this article, we report the change of optical properties for europium chelates on silver nanorods by near-field interactions. The silver rods were fabricated in a seed-growth method followed by depositing thin layers of silica on the surfaces. The europium chelates were physically absorbed in the silica layers on the silver rods. The silver rods were observed to exhibit two plasmon absorption bands from longitudinal and transverse directions, respectively, centered at 394 and 675 nm, close to absorption and emission bands from the Eu(III) chelates. As a result, the immobilized Eu(III) chelates on the silver rods should have strong interactions with the silver nanorods and lead to greatly improved optical properties. The Eu–Ag rod complexes were observed to have enhanced emission intensity up to 240-fold in comparison with the Eu(III) chelates in the metal-free silica templates. This enhancement is much larger than the value for the Eu(III) chelates on the gold rods or silver spheres indicating the presence of stronger interactions for the Eu(III) chelates with the silver rods. The interactions of Eu(III) chelates with the silver rods were also proven by extremely reduced lifetime. Moreover, the Eu–Ag rod complexes exhibited a polarized emission, which was also due to strong interactions of the Eu(III) chelates with the silver rods. All of these features may promise that the Eu(III)–Ag rod complexes have great potential for use as fluorescence imaging agents in biological assays. PMID:24363816

Vertical III-nitride thin-film power diode

DOE Office of Scientific and Technical Information (OSTI.GOV)

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.

75 FR 76636 - Anthropomorphic Test Devices; Hybrid III 6-Year-Old Child Test Dummy, Hybrid III 6-Year-Old...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-12-09

... test H06120 with the original femurs. Therefore, comparisons were made between pre- and post-test... [Docket No. NHTSA-2010-0147] RIN 2127-AK34 Anthropomorphic Test Devices; Hybrid III 6-Year-Old Child Test Dummy, Hybrid III 6-Year-Old Weighted Child Test Dummy AGENCY: National Highway Traffic Safety...

Universal description of III-V/Si epitaxial growth processes

NASA Astrophysics Data System (ADS)

Lucci, I.; Charbonnier, S.; Pedesseau, L.; Vallet, M.; Cerutti, L.; Rodriguez, J.-B.; Tournié, E.; Bernard, R.; Létoublon, A.; Bertru, N.; Le Corre, A.; Rennesson, S.; Semond, F.; Patriarche, G.; Largeau, L.; Turban, P.; Ponchet, A.; Cornet, C.

2018-06-01

Here, we experimentally and theoretically clarify III-V/Si crystal growth processes. Atomically resolved microscopy shows that monodomain three-dimensional islands are observed at the early stages of AlSb, AlN, and GaP epitaxy on Si, independently of misfit. It is also shown that complete III-V/Si wetting cannot be achieved in most III-V/Si systems. Surface/interface contributions to the free-energy variations are found to be prominent over strain relief processes. We finally propose a general and unified description of III-V/Si growth processes, including a description of the formation of antiphase boundaries.

DSM-III: the major achievements and an overview.

PubMed

Spitzer, R L; Williams, J B; Skodol, A E

1980-02-01

DSM-III will be published early this year. In the first part of this article the authors describe some of the major achievements of DSM-III: the process of its development, reaching consensus on many controversial diagnostic categories and a definition of mental disorder, the provision of diagnostic criteria and a multiaxial evaluation system, and the demonstration of improved diagnostic reliability. In the second part of the article the authors present an overview of DSM-III in which they describe its departures from DSM-II and the reasons for these changes. They conclude that in the next few years there should be systematic study of DSM-III in use, so that information about its strengths and limitations can be made available to those responsible for developing DSM-IV.

Dissociation kinetics of Fe(III)- and Al(III)-natural organic matter complexes at pH 6.0 and 8.0 and 25 °C

NASA Astrophysics Data System (ADS)

Jones, Adele M.; Pham, A. Ninh; Collins, Richard N.; Waite, T. David

2009-05-01

The rate at which iron- and aluminium-natural organic matter (NOM) complexes dissociate plays a critical role in the transport of these elements given the readiness with which they hydrolyse and precipitate. Despite this, there have only been a few reliable studies on the dissociation kinetics of these complexes suggesting half-times of some hours for the dissociation of Fe(III) and Al(III) from a strongly binding component of NOM. First-order dissociation rate constants are re-evaluated here at pH 6.0 and 8.0 and 25 °C using both cation exchange resin and competing ligand methods for Fe(III) and a cation exchange resin method only for Al(III) complexes. Both methods provide similar results at a particular pH with a two-ligand model accounting satisfactorily for the dissociation kinetics results obtained. For Fe(III), half-times on the order of 6-7 h were obtained for dissociation of the strong component and 4-5 min for dissociation of the weak component. For aluminium, the half-times were on the order of 1.5 h and 1-2 min for the strong and weak components, respectively. Overall, Fe(III) complexes with NOM are more stable than analogous complexes with Al(III), implying Fe(III) may be transported further from its source upon dilution and dispersion.

Octa- and hexametallic iron(III)-potassium phosphonate cages.

PubMed

Gopal, Kandasamy; Tuna, Floriana; Winpenny, Richard E P

2011-12-07

Two new iron(III)-potassium phosphonate cage complexes with {K(2)Fe(6)} and {K(2)Fe(4)} cores are reported. Magnetic studies reveal antiferromagnetic interactions between the Fe(III) centres occur in these cages.

Airborne Sun Photometer Measurements of Aerosol Optical Depth during SOLVE II: Comparison with SAGE III and POAM III Measurements

NASA Technical Reports Server (NTRS)

Russell, P.; Livingston, J.; Schmid, B.; Eilers, J.; Kolyer, R.; Redemann, J.; Yee, J.-H.; Trepte, C.; Thomason, L.; Zawodny, J.

2003-01-01

The 14-channel NASA Ames Airborne Tracking Sunphotometer (AATS-14) was operated aboard the NASA DC-8 during the Second SAGE III Ozone Loss and Validation Experiment (SOLVE II) and obtained successful measurements during the sunlit segments of eight science flights. These included six flights out of Kiruna, Sweden, one flight out of NASA Dryden Flight Research Center (DFRC), and the Kiruna-DFRC return transit flight. Values of spectral aerosol optical depth (AOD), columnar ozone and columnar water vapor have been derived from the AATS-14 measurements. In this paper, we focus on AATS-14 AOD data. In particular, we compare AATS-14 AOD spectra with temporally and spatially near-coincident measurements by the Stratospheric Aerosol and Gas Experiment III (SAGE III) and the Polar Ozone and Aerosol Measurement III (POAM III) satellite sensors. We examine the effect on retrieved AOD of uncertainties in relative optical airmass (the ratio of AOD along the instrument-to-sun slant path to that along the vertical path) at large solar zenith angles. Airmass uncertainties result fiom uncertainties in requisite assumed vertical profiles of aerosol extinction due to inhomogeneity along the viewing path or simply to lack of available data. We also compare AATS-14 slant path solar transmission measurements with coincident measurements acquired from the DC-8 by the NASA Langley Research Center Gas and Aerosol Measurement Sensor (GAMS).

REGIOSELECTIVE OXIDATIONS OF EQUILENIN DERIVATIVES CATALYZED BY A RHODIUM (III) PORPHYRIN COMPLEX-CONTRAST WITH THE MANGANESE (III) PORPHYRIN. (R826653)

EPA Science Inventory

Abstract

Equilenin acetate and dihydroequilenin acetate were oxidized with iodosobenzene and a rhodium(III) porphyrin catalyst. The selectivity of the reactions differs from that with the corresponding Mn(III) catalyst, or from that of free radical chain oxidation.

Cardiac Epithelial-Mesenchymal Transition Is Blocked by Monomethylarsonous Acid (III)

PubMed Central

Huang, Tianfang; Barnett, Joey V.; Camenisch, Todd D.

2014-01-01

Arsenic exposure during embryonic development can cause ischemic heart pathologies later in adulthood which may originate from impairment in proper blood vessel formation. The arsenic-associated detrimental effects are mediated by arsenite (iAsIII) and its most toxic metabolite, monomethylarsonous acid [MMA (III)]. The impact of MMA (III) on coronary artery development has not yet been studied. The key cellular process that regulates coronary vessel development is the epithelial-mesenchymal transition (EMT). During cardiac EMT, activated epicardial progenitor cells transform to mesenchymal cells to form the cellular components of coronary vessels. Smad2/3 mediated TGFβ2 signaling, the key regulator of cardiac EMT, is disrupted by arsenite exposure. In this study, we compared the cardiac toxicity of MMA (III) with arsenite. Epicardial progenitor cells are 15 times more sensitive to MMA (III) cytotoxicity when compared with arsenite. MMA (III) caused a significant blockage in epicardial cellular transformation and invasion at doses 10 times lower than arsenite. Key EMT genes including TGFβ ligands, TβRIII, Has2, CD44, Snail1, TBX18, and MMP2 were down regulated by MMA (III) exposure. MMA (III) disrupted Smad2/3 activation at a dose 20 times lower than arsenite. Both arsenite and MMA (III) significantly inhibited Erk1/2 and Erk5 phosphorylation. Nuclear translocation of Smad2/3 and Erk5 was also blocked by arsenical exposure. However, p38 activation, as well as smooth muscle differentiation, was refractory to the inhibition by the arsenicals. Collectively, these findings revealed that MMA (III) is a selective disruptor of cardiac EMT and as such may predispose to arsenic-associated cardiovascular disorders. PMID:25145660

Dissolved Mn(III) in water treatment works: Prevalence and significance.

PubMed

Johnson, Karen L; McCann, Clare M; Wilkinson, John-Luke; Jones, Matt; Tebo, Bradley M; West, Martin; Elgy, Christine; Clarke, Catherine E; Gowdy, Claire; Hudson-Edwards, Karen A

2018-09-01

Dissolved Mn(III) has been identified at all stages throughout a Water Treatment Works (WTW) receiving inflow from a peaty upland catchment in NE England. Ninety percent of the influent total manganese into the WTW is particulate Mn, in the form of Mn oxide (>0.2 μm). Approximately 9% (mean value, n = 22, range of 0-100%) of the dissolved (<0.2 μm) influent Mn is present as dissolved Mn(III). Mn(III) concentrations are highest (mean of 49% of total dissolved Mn; n = 26, range of 17-89%) within the WTW where water comes into contact with the organic-rich sludges which are produced as waste products in the WTW. These Mn(III)-containing wastewaters are recirculated to the head of the works and constitute a large input of Mn(III) into the WTW. This is the first report of Mn(III) being identified in a WTW. The ability of Mn(III) to act as both an oxidant and a reductant is of interest to the water industry. Understanding the formation and removal of Mn(III) within may help reduce Mn oxide deposits in pipe networks. Further understanding how the ratio of Mn(III) to Mn(II) can be used to optimise dissolved Mn removal would save the water industry significant money in reducing discoloration 'events' at the customers' tap. Copyright © 2018. Published by Elsevier Ltd.

VAC protocol for treatment of dogs with stage III hemangiosarcoma.

PubMed

Alvarez, Francisco J; Hosoya, Kenji; Lara-Garcia, Ana; Kisseberth, William; Couto, Guillermo

2013-01-01

Hemangiosarcomas (HSAs) are aggressive tumors with a high rate of metastasis. Clinical stage has been considered a negative prognostic factor for survival. The study authors hypothesized that the median survival time (MST) of dogs with metastatic (stage III) HSA treated with a vincristine, doxorubicin, and cyclophosphamide (VAC) chemotherapy protocol would not be different than those with stage I/II HSA. Sixty-seven dogs with HSA in different anatomic locations were evaluated retrospectively. All dogs received the VAC protocol as an adjuvant to surgery (n = 50), neoadjuvant (n = 3), or as the sole treatment modality (n = 14). There was no significant difference (P = 0.97) between the MST of dogs with stage III and stage I/II HSA. For dogs presenting with splenic HSA alone, there was no significant difference between the MST of dogs with stage III and stage I/II disease (P = 0.12). The overall response rate (complete response [CR] and partial response [PR]) was 86%). No unacceptable toxicities were observed. Dogs with stage III HSA treated with the VAC protocol have a similar prognosis to dogs with stage I/II HSA. Dogs with HSA and evidence of metastases at the time of diagnosis should not be denied treatment.

Electrical properties of dislocations in III-Nitrides

NASA Astrophysics Data System (ADS)

Cavalcoli, D.; Minj, A.; Pandey, S.; Cavallini, A.

2014-02-01

Research on GaN, AlN, InN (III-N) and their alloys is achieving new heights due their high potential applications in photonics and electronics. III-N semiconductors are mostly grown epitaxially on sapphire, and due to the large lattice mismatch and the differences in the thermal expansion coefficients, the structures usually contain many threading dislocations (TDs). While their structural properties have been widely investigated, their electrical characteristics and their role in the transport properties of the devices are still debated. In the present contribution we will show conductive AFM studies of TDs in GaN and Al/In GaN ternary alloys to evidence the role of strain, different surface polarity and composition on their electrical properties. Local I-V curves measured at TDs allowed us to clarify their role in the macroscopic electrical properties (leakage current, mobilities) of III-N based devices. Samples obtained by different growers (AIXTRON, III-V Lab) were studied. The comparison between the results obtained in the different alloys allowed us to understand the role of In and Al on the TDs electrical properties.

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.

The Mark III Hypercube-Ensemble Computers

NASA Technical Reports Server (NTRS)

Peterson, John C.; Tuazon, Jesus O.; Lieberman, Don; Pniel, Moshe

1988-01-01

Mark III Hypercube concept applied in development of series of increasingly powerful computers. Processor of each node of Mark III Hypercube ensemble is specialized computer containing three subprocessors and shared main memory. Solves problem quickly by simultaneously processing part of problem at each such node and passing combined results to host computer. Disciplines benefitting from speed and memory capacity include astrophysics, geophysics, chemistry, weather, high-energy physics, applied mechanics, image processing, oil exploration, aircraft design, and microcircuit design.

Chromium(iii) oxidation by biogenic manganese oxides with varying structural ripening.

PubMed

Tang, Yuanzhi; Webb, Samuel M; Estes, Emily R; Hansel, Colleen M

2014-09-20

Manganese (Mn) oxides, which are generally considered biogenic in origin within natural systems, are the only oxidants of Cr(iii) under typical environmental conditions. Yet the influence of Mn biooxide mineral structural evolution on Cr(iii) oxidation under varying geochemical conditions is unknown. In this study we examined the role of light, organic carbon, pH, and the structure of biogenic Mn oxides on Cr(iii) oxidation. Aging of Mn oxides produced by a marine bacterium within the widespread Roseobacter clade resulted in structural ripening from a colloidal hexagonal to a particulate triclinic birnessite phase. The structurally diverse Mn oxides were then reacted with aqueous Cr(iii) within artificial seawater in the presence or absence of carbon and light. Here we found that Cr(iii) oxidation capacity was highest at near neutral pH and in the combined presence of carbon and light. Mn oxide ripening from a hexagonal to a triclinic birnessite phase led to decreased Cr(iii) oxidation in the presence of carbon and light, whereas no change in reactivity was observed in the absence of carbon and/or in the dark. As only minimal Cr(iii) oxidation was observed in the absence of Mn oxides, these results strongly point to coupled Mn oxide- and photo-induced generation of organic and/or oxygen radicals involved in Cr(iii) oxidation. Based on Mn oxide concentration and structural trends, we postulate that Mn(ii) produced from the oxidation of Cr(iii) by the primary Mn oxide is recycled in the presence of organics and light conditions, (re)generating secondary hexagonal birnessite and thereby allowing for continuous oxidation of Cr(iii). In the absence of this Mn oxide regeneration, Cr(iii) induced structural ripening of the hexagonal birnessite precludes further Cr(iii) oxidation. These results highlight the complexity of reactions involved in Mn oxide mediated Cr(iii) oxidation and suggest that photochemical carbon reactions are requisite for sustained Cr(iii) oxidation

Reporting of the translation and cultural adaptation procedures of the Addenbrooke's Cognitive Examination version III (ACE-III) and its predecessors: a systematic review.

PubMed

Mirza, Nadine; Panagioti, Maria; Waheed, Muhammad Wali; Waheed, Waquas

2017-09-13

The ACE-III, a gold standard for screening cognitive impairment, is restricted by language and culture, with no uniform set of guidelines for its adaptation. To develop guidelines a compilation of all the adaptation procedures undertaken by adapters of the ACE-III and its predecessors is needed. We searched EMBASE, Medline and PsychINFO and screened publications from a previous review. We included publications on adapted versions of the ACE-III and its predecessors, extracting translation and cultural adaptation procedures and assessing their quality. We deemed 32 papers suitable for analysis. 7 translation steps were identified and we determined which items of the ACE-III are culturally dependent. This review lists all adaptations of the ACE, ACE-R and ACE-III, rates the reporting of their adaptation procedures and summarises adaptation procedures into steps that can be undertaken by adapters.

Photoluminescence studies on the complexation of Eu(III) and Tb(III) with acetohydroxamic acid (AHA) in nitrate medium.

PubMed

Pathak, P N; Mohapatra, M; Godbole, S V

2013-11-01

UREX process has been proposed for selective extraction of U(VI) and Tc(VII) from nitric acid medium (∼1M HNO3) using tri-n-butyl phosphate (TBP) as extractant and retaining Pu, Np and fission products in the aqueous phase. The feasibility of the use of luminescence spectroscopy as a technique to understand the complexation of trivalent f-elements cations viz. Eu(III) and Tb(III) with acetohydroxamic acid (AHA) in nitric acid medium has been examined. The luminescence lifetimes for the 1×10(-3)M Eu(III) and AHA complex system decreased with increased AHA concentration from 116±0.2μs (no AHA) to 1.6±0.1μs (0.1M AHA) which was attributed to dynamic quenching. The corrected fluorescence intensities were used to calculate the stability constant (log K) for the formation of 1:1 Eu(3+)-AHA complex as 1.42±0.64 under the conditions of this study. By contrast, the Tb(III)-AHA system at pH 3 (HNO3) did not show any significant variation in the life times of the excited state (364±9μs) suggesting the absence of dynamic quenching. The spectral changes in Tb(III)-AHA system showed the formation of 1:1 complex (log K: 1.72±0.21). These studies suggest that the extent of AHA complexation with the rare earth elements will be insignificant as compared to tetravalent metal ions Pu(IV) and Np(IV) under UREX process conditions. Copyright © 2013 Elsevier B.V. All rights reserved.

Photoluminescence studies on the complexation of Eu(III) and Tb(III) with acetohydroxamic acid (AHA) in nitrate medium

NASA Astrophysics Data System (ADS)

Pathak, P. N.; Mohapatra, M.; Godbole, S. V.

2013-11-01

UREX process has been proposed for selective extraction of U(VI) and Tc(VII) from nitric acid medium (∼1 M HNO3) using tri-n-butyl phosphate (TBP) as extractant and retaining Pu, Np and fission products in the aqueous phase. The feasibility of the use of luminescence spectroscopy as a technique to understand the complexation of trivalent f-elements cations viz. Eu(III) and Tb(III) with acetohydroxamic acid (AHA) in nitric acid medium has been examined. The luminescence lifetimes for the 1 × 10-3 M Eu(III) and AHA complex system decreased with increased AHA concentration from 116 ± 0.2 μs (no AHA) to 1.6 ± 0.1 μs (0.1 M AHA) which was attributed to dynamic quenching. The corrected fluorescence intensities were used to calculate the stability constant (log K) for the formation of 1:1 Eu3+-AHA complex as 1.42 ± 0.64 under the conditions of this study. By contrast, the Tb(III)-AHA system at pH 3 (HNO3) did not show any significant variation in the life times of the excited state (364 ± 9 μs) suggesting the absence of dynamic quenching. The spectral changes in Tb(III)-AHA system showed the formation of 1:1 complex (log K: 1.72 ± 0.21). These studies suggest that the extent of AHA complexation with the rare earth elements will be insignificant as compared to tetravalent metal ions Pu(IV) and Np(IV) under UREX process conditions.

Identification of the lipopolysaccharide modifications controlled by the Salmonella PmrA/PmrB system mediating resistance to Fe(III) and Al(III)

PubMed Central

Nishino, Kunihiko; Hsu, Fong-Fu; Turk, John; Cromie, Michael J; Wösten, Marc M S M; Groisman, Eduardo A

2006-01-01

Iron is an essential metal but can be toxic in excess. While several homeostatic mechanisms prevent oxygen-dependent killing promoted by Fe(II), little is known about how cells cope with Fe(III), which kills by oxygen-independent means. Several Gram-negative bacterial species harbour a regulatory system – termed PmrA/PmrB – that is activated by and required for resistance to Fe(III). We now report the identification of the PmrA-regulated determinants mediating resistance to Fe(III) and Al(III) in Salmonella enterica serovar Typhimurium. We establish that these determinants remodel two regions of the lipopolysaccharide, decreasing the negative charge of this major constituent of the outer membrane. Remodelling entails the covalent modification of the two phosphates in the lipid A region with phosphoethanolamine and 4-aminoarabinose, which has been previously implicated in resistance to polymyxin B, as well as dephosphorylation of the Hep(II) phosphate in the core region by the PmrG protein. A mutant lacking the PmrA-regulated Fe(III) resistance genes bound more Fe(III) than the wild-type strain and was defective for survival in soil, suggesting that these PmrA-regulated lipopolysaccharide modifications aid Salmonella's survival and spread in non-host environments. PMID:16803591

Trichomonads, hydrogenosomes and drug resistance.

PubMed

Kulda, J

1999-02-01

Trichomonas vaginalis and Tritrichomonas foetus are sexually transmitted pathogens of the genito-urinary tract of humans and cattle, respectively. These organisms are amitochondrial anaerobes possessing hydrogenosomes, double membrane-bound organelles involved in catabolic processes extending glycolysis. The oxidative decarboxylation of pyruvate in hydrogenosomes is coupled to ATP synthesis and linked to ferredoxin-mediated electron transport. This pathway is responsible for metabolic activation of 5-nitroimidazole drugs, such as metronidazole, used in chemotherapy of trichomoniasis. Prolonged cultivation of trichomonads under sublethal pressure of metronidazole results in development of drug resistance. In both pathogenic species the resistance develops in a multistep process involving a sequence of stages that differ in drug susceptibility and metabolic activities. Aerobic resistance, similar to that occurring in clinical isolates of T. vaginalis from treatment-refractory patients, appears as the earliest stage. The terminal stage is characterised by stable anaerobic resistance at which the parasites show very high levels of minimal lethal concentration for metronidazole under anaerobic conditions (approximately 1000 microg ml(-1)). The key event in the development of resistance is progressive decrease and eventual loss of the pyruvate:ferredoxin oxidoreductase so that the drug-activating process is averted. In T. vaginalis at least, the development of resistance is also accompanied by decreased expression of ferredoxin. The pyruvate:ferredoxin oxidoreductase deficiency completely precludes metronidazole activation in T. foetus, while T. vaginalis possesses an additional drug-activating system which must be eliminated before the full resistance is acquired. This alternative pathway involves the hydrogenosomal malic enzyme and NAD:ferredoxin oxidoreductase. Metronidazole-resistant trichomonads compensate for the hydrogenosomal deficiency by an increased rate of

A Novel Phenanthrene Dioxygenase from Nocardioides sp. Strain KP7: Expression in Escherichia coli

PubMed Central

Saito, Atsushi; Iwabuchi, Tokuro; Harayama, Shigeaki

2000-01-01

Nocardioides sp. strain KP7 grows on phenanthrene but not on naphthalene. This organism degrades phenanthrene via 1-hydroxy-2-naphthoate, o-phthalate, and protocatechuate. The genes responsible for the degradation of phenanthrene to o-phthalate (phd) were found by Southern hybridization to reside on the chromosome. A 10.6-kb DNA fragment containing eight phd genes was cloned and sequenced. The phdA, phdB, phdC, and phdD genes, which encode the α and β subunits of the oxygenase component, a ferredoxin, and a ferredoxin reductase, respectively, of phenanthrene dioxygenase were identified. The gene cluster, phdAB, was located 8.3 kb downstream of the previously characterized phdK gene, which encodes 2-carboxybenzaldehyde dehydrogenase. The phdCD gene cluster was located 2.9 kb downstream of the phdB gene. PhdA and PhdB exhibited moderate (less than 60%) sequence identity to the α and β subunits of other ring-hydroxylating dioxygenases. The PhdC sequence showed features of a [3Fe-4S] or [4Fe-4S] type of ferredoxin, not of the [2Fe-2S] type of ferredoxin that has been found in most of the reported ring-hydroxylating dioxygenases. PhdD also showed moderate (less than 40%) sequence identity to known reductases. The phdABCD genes were expressed poorly in Escherichia coli, even when placed under the control of strong promoters. The introduction of a Shine-Dalgarno sequence upstream of each initiation codon of the phdABCD genes improved their expression in E. coli. E. coli cells carrying phdBCD or phdACD exhibited no phenanthrene-degrading activity, and those carrying phdABD or phdABC exhibited phenanthrene-degrading activity which was significantly less than that in cells carrying the phdABCD genes. It was thus concluded that all of the phdABCD genes are necessary for the efficient expression of phenanthrene-degrading activity. The genetic organization of the phd genes, the phylogenetically diverged positions of these genes, and an unusual type of ferredoxin component

Selective repression of SINE transcription by RNA polymerase III.

PubMed

Varshney, Dhaval; Vavrova-Anderson, Jana; Oler, Andrew J; Cairns, Bradley R; White, Robert J

2015-01-01

A million copies of the Alu short interspersed nuclear element (SINE) are scattered throughout the human genome, providing ∼11% of our total DNA. SINEs spread by retrotransposition, using a transcript generated by RNA polymerase (pol) III from an internal promoter. Levels of these pol III-dependent Alu transcripts are far lower than might be expected from the abundance of the template. This was believed to reflect transcriptional suppression through DNA methylation, denying pol III access to most SINEs through chromatin-mediated effects. Contrary to expectations, our recent study found no evidence that methylation of SINE DNA reduces its occupancy or expression by pol III. However, histone H3 associated with SINEs is prominently methylated on lysine 9, a mark that correlates with transcriptional silencing. The SUV39 methyltransferases that deposit this mark can be found at many SINEs. Furthermore, a selective inhibitor of SUV39 stimulates pol III recruitment to these loci, as well as SINE expression. These data suggest that methylation of histone H3 rather than DNA may mediate repression of SINE transcription by pol III, at least under the conditions we studied.

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.

Lhires III High Resolution Spectrograph

NASA Astrophysics Data System (ADS)

Thizy, O.

2007-05-01

By spreading the light from celestial objects by wavelength, spectroscopists are like detectives looking for clues and identifying guilty phenomena that shape their spectra. We will review some basic principles in spectroscopy that will help, at our amateur level, to understand how spectra are shaped. We will review the Lhires III highresolution spectrograph Mark Three that was designed to reveal line profile details and subtle changes. Then, we will do an overview of educational and scientific projects that are conducted with the Lhires III and detail the COROT Be star program and the BeSS database for which the spectrograph is a key instrument.

Investigation on the co-luminescence effect of europium (III)-lanthanum(III)-dopamine-sodium dodecylbenzene sulfonate system and its application.

PubMed

Si, Hailin; Zhao, Fang; Cai, Huan

2013-01-01

A novel luminescence, enhancement phenomenon in the europium(III)-dopamine-sodium dodecylbenzene sulfonate system was observed when lanthanum(III) was added. Based on this, a sensitive co-luminescence method was established for the determination of dopamine. The luminescence signal for the europium (III)-lanthanum(III)-dopamine-sodium dodecylbenzene sulfonate system was monitored at λ(ex) = 300 nm, λ(em) = 618 nm and pH 8.3. Under optimized conditions, the enhanced luminescence signal responded linearly to the concentration of dopamine in the range 1.0 × 10(-10)-5.0 × 10(-7) mol/L with a correlation coefficient of 0.9993 (n = 11). The detection limit (3σ) was 2.7 × 10(-11) mol/L and the relative standard deviation for 11 parallel measurements of 3.0 × 10(-8) mol/L dopamine was 1.9%. The presented method was successfully applied for the estimation of dopamine in samples of pharmaceutical preparations, human serum and urine. The possible luminescence enhancement mechanism of the system is discussed briefly. Copyright © 2013 John Wiley & Sons, Ltd.

Genetically engineered T cells to target EGFRvIII expressing glioblastoma.

PubMed

Bullain, Szofia S; Sahin, Ayguen; Szentirmai, Oszkar; Sanchez, Carlos; Lin, Ning; Baratta, Elizabeth; Waterman, Peter; Weissleder, Ralph; Mulligan, Richard C; Carter, Bob S

2009-09-01

Glioblastoma remains a significant therapeutic challenge, warranting further investigation of novel therapies. We describe an immunotherapeutic strategy to treat glioblastoma based on adoptive transfer of genetically modified T-lymphocytes (T cells) redirected to kill EGFRvIII expressing gliomas. We constructed a chimeric immune receptor (CIR) specific to EGFRvIII, (MR1-zeta). After in vitro selection and expansion, MR1-zeta genetically modified primary human T-cells specifically recognized EGFRvIII-positive tumor cells as demonstrated by IFN-gamma secretion and efficient tumor lysis compared to control CIRs defective in EGFRvIII binding (MRB-zeta) or signaling (MR1-delzeta). MR1-zeta expressing T cells also inhibited EGFRvIII-positive tumor growth in vivo in a xenografted mouse model. Successful targeting of EGFRvIII-positive tumors via adoptive transfer of genetically modified T cells may represent a new immunotherapy strategy with great potential for clinical applications.

Energy-converting [NiFe] hydrogenases from archaea and extremophiles: ancestors of complex I.

PubMed

Hedderich, Reiner

2004-02-01

[NiFe] hydrogenases are well-characterized enzymes that have a key function in the H2 metabolism of various microorganisms. In the recent years a subfamily of [NiFe] hydrogenases with unique properties has been identified. The members of this family form multisubunit membrane-bound enzyme complexes composed of at least four hydrophilic and two integral membrane proteins. These six conserved subunits, which built the core of these hydrogenases, have closely related counterparts in energy-conserving NADH:quinone oxidoreductases (complex I). However, the reaction catalyzed by these hydrogenases differs significantly from the reaction catalyzed by complex I. For some of these hydrogenases the physiological role is to catalyze the reduction of H+ with electrons derived from reduced ferredoxins or poly-ferredoxins. This exergonic reaction is coupled to energy conservation by means of electron-transport phosphorylation. Other members of this hydrogenase family mainly function to provide the cell with reduced ferredoxin with H2 as electron donor in a reaction driven by reverse electron transport. As complex I these hydrogenases function as ion pumps and have therefore been designated as energy-converting [NiFe] hydrogenases.

Neutrino Background from Population III Stars

NASA Astrophysics Data System (ADS)

Iocco, Fabio

2011-12-01

Population III Stars (PopIII) are the first generation of stars formed from the collapse of the very first structures in the Universe. Their peculiar chemical composition (metal-free, resembling the Primordial Nucleosynthesis yields) affects their formation and evolution and makes them unusually big and hot stars. They are good candidates for the engines of Reionization of the Universe although their direct observation is extremely difficult. Here we summarize a study of their expected diffuse low-energy neutrino background flux at Earth.

Gd(III)-Gd(III) EPR distance measurements--the range of accessible distances and the impact of zero field splitting.

PubMed

Dalaloyan, Arina; Qi, Mian; Ruthstein, Sharon; Vega, Shimon; Godt, Adelheid; Feintuch, Akiva; Goldfarb, Daniella

2015-07-28

Gd(III) complexes have emerged as spin labels for distance determination in biomolecules through double-electron-electron resonance (DEER) measurements at high fields. For data analysis, the standard approach developed for a pair of weakly coupled spins with S = 1/2 was applied, ignoring the actual properties of Gd(III) ions, i.e. S = 7/2 and ZFS (zero field splitting) ≠ 0. The present study reports on a careful investigation on the consequences of this approach, together with the range of distances accessible by DEER with Gd(III) complexes as spin labels. The experiments were performed on a series of specifically designed and synthesized Gd-rulers (Gd-PyMTA-spacer-Gd-PyMTA) covering Gd-Gd distances of 2-8 nm. These were dissolved in D2O-glycerol-d8 (0.03-0.10 mM solutions) which is the solvent used for the corresponding experiments on biomolecules. Q- and W-band DEER measurements, followed by data analysis using the standard data analysis approach, used for S = 1/2 pairs gave the distance-distribution curves, of which the absolute maxima agreed very well with the expected distances. However, in the case of the short distances of 2.1 and 2.9 nm, the distance distributions revealed additional peaks. These are a consequence of neglecting the pseudo-secular term in the dipolar Hamiltonian during the data analysis, as is outlined in a theoretical treatment. At distances of 3.4 nm and above, disregarding the pseudo-secular term leads to a broadening of a maximum of 0.4 nm of the distance-distribution curves at half height. Overall, the distances of up to 8.3 nm were determined, and the long evolution time of 16 μs at 10 K indicates that a distance of up to 9.4 nm can be accessed. A large distribution of the ZFS parameter, D, as is found for most Gd(III) complexes in a frozen solution, is crucial for the application of Gd(III) complexes as spin labels for distance determination via Gd(III)-Gd(III) DEER, especially for short distances. The larger ZFS of Gd-PyMTA, in

Particle Aggregation During Fe(III) Bioreduction in Nontronite

NASA Astrophysics Data System (ADS)

Jaisi, D. P.; Dong, H.; Hi, Z.; Kim, J.

2005-12-01

This study was performed to evaluate the rate and mechanism of particle aggregation during bacterial Fe (III) reduction in different size fractions of nontronite and to investigate the role of different factors contributing to particle aggregation. To achieve this goal, microbial Fe(III) reduction experiments were performed with lactate as an electron donor, Fe(III) in nontronite as an electron acceptor, and AQDS as an electron shuttle in bicarbonate buffer using Shewanella putrefaceins CN32. These experiments were performed with and without Na- pyrophosphate as a dispersant in four size fractions of nontronite (0.12-0.22, 0.41-0.69, 0.73-0.96 and 1.42-1.8 mm). The rate of nontronite aggregation during the Fe(III) bioreduction was measured by analyzing particle size distribution using photon correlation spectroscopy (PCS) and SEM images analysis. Similarly, the changes in particle morphology during particle aggregation were determined by analyses of SEM images. Changes in particle surface charge were measured with electrophoretic mobility analyzer. The protein and carbohydrate fraction of EPS produced by cells during Fe(III) bioreduction was measured using Bradford and phenol-sulfuric acid extraction method, respectively. In the presence of the dispersant, the extent of Fe(III) bioreduction was 11.5-12.2% within the first 56 hours of the experiment. There was no measurable particle aggregation in control experiments. The PCS measurements showed that the increase in the effective diameter (95% percentile) was by a factor of 3.1 and 1.9 for particle size of 0.12-0.22 mm and 1.42-1.80 mm, respectively. The SEM image analyses also gave the similar magnitude of increase in particle size. In the absence of the dispersant, the extent of Fe(III) bioreduction was 13.4-14.5% in 56 hours of the experiment. The rate of aggregation was higher than that in the presence of the dispersant. The increase in the effective diameter (95% percentile) was by a factor of 13.6 and 4.1 for

Exploring the Influence of Diamagnetic Ions on the Mechanism of Magnetization Relaxation in {CoIII2LnIII2} (Ln = Dy, Tb, Ho) "Butterfly" Complexes.

PubMed

Vignesh, Kuduva R; Langley, Stuart K; Murray, Keith S; Rajaraman, Gopalan

2017-03-06

The synthesis and magnetic and theoretical studies of three isostructural heterometallic [Co III 2 Ln III 2 (μ 3 -OH) 2 (o-tol) 4 (mdea) 2 (NO 3 ) 2 ] (Ln = Dy (1), Tb (2), Ho (3)) "butterfly" complexes are reported (o-tol = o-toluate, (mdea) 2- = doubly deprotonated N-methyldiethanolamine). The Co III ions are diamagnetic in these complexes. Analysis of the dc magnetic susceptibility measurements reveal antiferromagnetic exchange coupling between the two Ln III ions for all three complexes. ac magnetic susceptibility measurements reveal single-molecule magnet (SMM) behavior for complex 1, in the absence of an external magnetic field, with an anisotropy barrier U eff of 81.2 cm -1 , while complexes 2 and 3 exhibit field induced SMM behavior, with a U eff value of 34.2 cm -1 for 2. The barrier height for 3 could not be quantified. To understand the experimental observations, we performed DFT and ab initio CASSCF+RASSI-SO calculations to probe the single-ion properties and the nature and magnitude of the Ln III -Ln III magnetic coupling and to develop an understanding of the role the diamagnetic Co III ion plays in the magnetization relaxation. The calculations were able to rationalize the experimental relaxation data for all complexes and strongly suggest that the Co III ion is integral to the observation of SMM behavior in these systems. Thus, we explored further the effect that the diamagnetic Co III ions have on the magnetization blocking of 1. We did this by modeling a dinuclear {Dy III 2 } complex (1a), with the removal of the diamagnetic ions, and three complexes of the types {K I 2 Dy III 2 } (1b), {Zn II 2 Dy III 2 } (1c), and {Ti IV 2 Dy III 2 } (1d), each containing a different diamagnetic ion. We found that the presence of the diamagnetic ions results in larger negative charges on the bridging hydroxides (1b > 1c > 1 > 1d), in comparison to 1a (no diamagnetic ion), which reduces quantum tunneling of magnetization effects, allowing for more desirable SMM

[Brownian dynamics simulations of protein-protein interactions in photosynthetic electron transport chain].

PubMed

Khruschev, S S; Abaturova, A M; Diakonova, A N; Fedorov, V A; Ustinin, D M; Kovalenko, I B; Riznichenko, G Yu; Rubin, A B

2015-01-01

The application of Brownian dynamics for simulation of transient protein-protein interactions is reviewed. The review focuses on theoretical basics of Brownian dynamics method, its particular implementations, advantages and drawbacks of the method. The outlook for future development of Brownian dynamics-based simulation techniques is discussed. Special attention is given to analysis of Brownian dynamics trajectories. The second part of the review is dedicated to the role of Brownian dynamics simulations in studying photosynthetic electron transport. Interactions of mobile electron carriers (plastocyanin, cytochrome c6, and ferredoxin) with their reaction partners (cytochrome b6f complex, photosystem I, ferredoxin:NADP-reductase, and hydrogenase) are considered.

Oral Assessment Kit, Levels II & III. Draft.

ERIC Educational Resources Information Center

Agrelo-Gonzalez, Maria; And Others

The assessment packet includes a series of oral tests to help develop speaking as an integral part of second language instruction at levels II and III. It contains: 8 mini-tests for use at level II; 9 mini-tests for use at level III; a rating scale and score sheet masters for evaluating performance on these tests; and a collection of suggested…

Oxidative Formation and Removal of Complexed Mn(III) by Pseudomonas Species

PubMed Central

Wright, Mitchell H.; Geszvain, Kati; Oldham, Véronique E.; Luther, George W.; Tebo, Bradley M.

2018-01-01

The observation of significant concentrations of soluble Mn(III) complexes in oxic, suboxic, and some anoxic waters has triggered a re-evaluation of the previous Mn paradigm which focused on the cycling between soluble Mn(II) and insoluble Mn(III,IV) species as operationally defined by filtration. Though Mn(II) oxidation in aquatic environments is primarily bacterially-mediated, little is known about the effect of Mn(III)-binding ligands on Mn(II) oxidation nor on the formation and removal of Mn(III). Pseudomonas putida GB-1 is one of the most extensively investigated of all Mn(II) oxidizing bacteria, encoding genes for three Mn oxidases (McoA, MnxG, and MopA). P. putida GB-1 and associated Mn oxidase mutants were tested alongside environmental isolates Pseudomonas hunanensis GSL-007 and Pseudomonas sp. GSL-010 for their ability to both directly oxidize weakly and strongly bound Mn(III), and to form these complexes through the oxidation of Mn(II). Using Mn(III)-citrate (weak complex) and Mn(III)-DFOB (strong complex), it was observed that P. putida GB-1, P. hunanensis GSL-007 and Pseudomonas sp. GSL-010 and mutants expressing only MnxG and McoA were able to directly oxidize both species at varying levels; however, no oxidation was detected in cultures of a P. putida mutant expressing only MopA. During cultivation in the presence of Mn(II) and citrate or DFOB, P. putida GB-1, P. hunanensis GSL-007 and Pseudomonas sp. GSL-010 formed Mn(III) complexes transiently as an intermediate before forming Mn(III/IV) oxides with the overall rates and extents of Mn(III,IV) oxide formation being greater for Mn(III)-citrate than for Mn(III)-DFOB. These data highlight the role of bacteria in the oxidative portion of the Mn cycle and suggest that the oxidation of strong Mn(III) complexes can occur through enzymatic mechanisms involving multicopper oxidases. The results support the observations from field studies and further emphasize the complexity of the geochemical cycling of

Oxidative Formation and Removal of Complexed Mn(III) by Pseudomonas Species.

PubMed

Wright, Mitchell H; Geszvain, Kati; Oldham, Véronique E; Luther, George W; Tebo, Bradley M

2018-01-01

The observation of significant concentrations of soluble Mn(III) complexes in oxic, suboxic, and some anoxic waters has triggered a re-evaluation of the previous Mn paradigm which focused on the cycling between soluble Mn(II) and insoluble Mn(III,IV) species as operationally defined by filtration. Though Mn(II) oxidation in aquatic environments is primarily bacterially-mediated, little is known about the effect of Mn(III)-binding ligands on Mn(II) oxidation nor on the formation and removal of Mn(III). Pseudomonas putida GB-1 is one of the most extensively investigated of all Mn(II) oxidizing bacteria, encoding genes for three Mn oxidases (McoA, MnxG, and MopA). P. putida GB-1 and associated Mn oxidase mutants were tested alongside environmental isolates Pseudomonas hunanensis GSL-007 and Pseudomonas sp. GSL-010 for their ability to both directly oxidize weakly and strongly bound Mn(III), and to form these complexes through the oxidation of Mn(II). Using Mn(III)-citrate (weak complex) and Mn(III)-DFOB (strong complex), it was observed that P. putida GB-1, P. hunanensis GSL-007 and Pseudomonas sp. GSL-010 and mutants expressing only MnxG and McoA were able to directly oxidize both species at varying levels; however, no oxidation was detected in cultures of a P. putida mutant expressing only MopA. During cultivation in the presence of Mn(II) and citrate or DFOB, P. putida GB-1, P. hunanensis GSL-007 and Pseudomonas sp. GSL-010 formed Mn(III) complexes transiently as an intermediate before forming Mn(III/IV) oxides with the overall rates and extents of Mn(III,IV) oxide formation being greater for Mn(III)-citrate than for Mn(III)-DFOB. These data highlight the role of bacteria in the oxidative portion of the Mn cycle and suggest that the oxidation of strong Mn(III) complexes can occur through enzymatic mechanisms involving multicopper oxidases. The results support the observations from field studies and further emphasize the complexity of the geochemical cycling of

Expansion/Facemask Treatment of an Adult Class III Malocclusion.

PubMed

Jackson, Gregory W; Kravitz, Neal D

2014-01-01

The orthodontic treatment of class III malocclusion with a maxillary deficiency is often treated with maxillary protraction with or without expansion. Skeletal and dental changes have been documented which have combined for the protraction of the maxilla and the correction of the class III malocclusion. Concerning the ideal time to treat a developing class III malocclusion, studies have reported that, although early treatment may be the most effective, face mask therapy can provide a viable option for older children as well. But what about young adults? Can the skeletal and dental changes seen in expansion/facemask therapy in children and adolescents be demonstrated in this age group as well, possibly eliminating the need for orthodontic dental camouflage treatment or orthognathic surgery? A case report is presented of an adult class III malocclusion with a Class III skeletal pattern and maxillary retrusion. Treatment was with nonextraction, comprehensive edgewise mechanics with slow maxillary expansion with a bonded expander and protraction facemask.

Methods for forming group III-arsenide-nitride semiconductor materials

NASA Technical Reports Server (NTRS)

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

2002-01-01

Methods are disclosed for forming Group III-arsenide-nitride semiconductor materials. 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 crystals 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 crystals can be accomplished by growing thin layers of elements or compounds in sequences that result in the overall lattice match and bandgap desired.

Investigation of complexes tannic acid and myricetin with Fe(III)

NASA Astrophysics Data System (ADS)

Sungur, Şana; Uzar, Atike

2008-01-01

The pH dependence of the complexes was determined by both potentiometric and spectrophotometric studies. Stability constants and stoichiometries of the formed complexes were determined using slope ratio method. Fe(III) was formed complexes with tannic acid of various stoichiometries, which in the 1:1 molar ratio at pH < 3, in the 2:1 molar ratio at pH 3-7 and in the 4:1 molar ratio at pH > 7. Fe(III) was formed complexes with myricetin in the 1:2 molar ratio at pH 4 and 5 and in the 1:1 molar ratio at pH 6. Stability constant values were found to be 10 5 to 10 17 and 10 5 to 10 9 for Fe(III)-tannic acid complexes and Fe(III)-myricetin complexes. Both tannic acid and myricetin were possessed minimum affinities to Cu(II) and Zn(II). They had less affinity for Al(III) than for Fe(III).

Kinetic modeling of antimony(III) oxidation and sorption in soils.

PubMed

Cai, Yongbing; Mi, Yuting; Zhang, Hua

2016-10-05

Kinetic batch and saturated column experiments were performed to study the oxidation, adsorption and transport of Sb(III) in two soils with contrasting properties. Kinetic and column experiment results clearly demonstrated the extensive oxidation of Sb(III) in soils, and this can in return influence the adsorption and transport of Sb. Both sorption capacity and kinetic oxidation rate were much higher in calcareous Huanjiang soil than in acid red Yingtan soil. The results indicate that soil serve as a catalyst in promoting oxidation of Sb(III) even under anaerobic conditions. A PHREEQC model with kinetic formulations was developed to simulate the oxidation, sorption and transport of Sb(III) in soils. The model successfully described Sb(III) oxidation and sorption data in kinetic batch experiment. It was less successful in simulating the reactive transport of Sb(III) in soil columns. Additional processes such as colloid facilitated transport need to be quantified and considered in the model. Copyright © 2016 Elsevier B.V. All rights reserved.

Th(As(III)4As(V)4O18): a mixed-valent oxoarsenic(III)/arsenic(V) actinide compound obtained under extreme conditions.

PubMed

Yu, Na; Klepov, Vladislav V; Kegler, Philip; Bosbach, Dirk; Albrecht-Schmitt, Thomas E; Alekseev, Evgeny V

2014-08-18

A high-temperature/high-pressure method was employed to investigate phase formation in the Th(NO3)4·5H2O-As2O3-CsNO3 system. It was observed that an excess of arsenic(III) in starting system leads to the formation of Th(As(III)4As(V)4O18), which is representative of a rare class of mixed-valent arsenic(III)/arsenic(V) compounds. This compound was studied with X-ray diffraction, energy-dispersive X-ray, and Raman spectroscopy methods. Crystallographic data show that Th(As(III)4As(V)4O18) is built from (As(III)4As(V)4O18)(4-) layers connected through Th atoms. The arsenic layers are found to be isoreticular to those in previously reported As2O3 and As3O5(OH), and the geometric differences between them are discussed. Bands in the Raman spectrum are assigned with respect to the presence of AsO3 and AsO4 groups.

Luminescent amine sensor based on europium(III) chelate.

PubMed

Petrochenkova, Nataliya V; Mirochnik, Anatolii G; Emelina, Tatyana B; Sergeev, Alexander A; Leonov, Andrei A; Voznesenskii, Sergey S

2018-07-05

The effect of methylamine vapor on luminescence of Eu(III) tris-benzoylacetonate (I) immobilized in thin-layer chromatography plates has been investigated. It has been revealed that interaction of I with analyte vapor results in increase of the intensity of Eu(III) luminescence. The mechanism of the effect of methylamine vapors on intensification of the Eu(III) luminescence has been suggested using the data of IR spectroscopy and quantum chemistry calculations. The mechanism of luminescence sensitization consists in bonding of an analyte molecule with a water molecule into the coordination sphere of Eu(III). As a result, the bond of a water molecule with the luminescence centre weakens, rigid structural fragment including europium ion, water and methylamine molecules forms. The presence of such fragment must naturally promote decrease of influence of OH-vibrations on luminescence of the complex I. Copyright © 2018 Elsevier B.V. All rights reserved.

[CrIII(NCMe)6]3+--a labile CrIII source enabling formation of Cr[M(CN)6] (M=V, Cr, Mn, Fe) Prussian blue-type magnetic materials.

PubMed

Nelson, Kendric J; Daniels, Matthew C; Reiff, William M; Troff, Shayla A; Miller, Joel S

2007-11-26

The kinetic inertness of the hexaaquachromium(III) (kH2O=2.4x10(-6) s(-1)) has led to challenges with respect to incorporating CrIII ions into Prussian blue-type materials; however, hexakis(acetonitrile)chromium(III) was shown to be substantially more labile (approximately 10(4) times) and enables a new synthetic route for the synthesis of these materials via nonaqueous solvents. The synthesis, spectroscopic, and physical properties of Cr[M(CN)6] (M=V, Cr, Mn, Fe) Prussian blue analogues synthesized from [CrIII(NCMe)6]3+ and the corresponding [MIII(CN)6]3- are described. All these compounds {(NEt4)0.02CrIII[VIII(CN)6]0.98(BF4)(0.08).0.10MeCN (1), CrIII[CrIII(CN)6].0.16MeCN (2), CrIII[MnIII(CN)6].0.10MeCN (3), and (NEt4)0.04CrIII0.64CrIV0.40[FeII(CN)6]0.40[FeIII(CN)6]0.60(BF4)(0.16).1.02MeCN (4)} are ferrimagnets exhibiting cluster-glass behavior. Strong antiferromagnetic coupling was observed for M=V, Cr, and Mn with Weiss constants (theta) ranging from -132 to -524 K; and in 2, where the strongest coupling is observed (theta=-524 K), the highest Tc (110 K) value was observed. Weak antiferromagnetic coupling was observed for M=Fe (theta=-12 K) leading to the lowest Tc (3 K) value in this series. Weak coupling and the low Tc value observed in 4 were additionally contributed by the presence of both [FeII(CN)6]4- and [FeIII(CN)6]3- as confirmed by 57Fe-Mössbauer spectroscopy.

Revised SNAP III Training Manual

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moss, Calvin Elroy; Gonzales, Samuel M.; Myers, William L.

The Shielded Neutron Assay Probe (SNAP) technique was developed to determine the leakage neutron source strength of a radioactive object. The original system consisted of an Eberline TM Mini-scaler and discrete neutron detector. The system was operated by obtaining the count rate with the Eberline TM instrument, determining the absolute efficiency from a graph, and calculating the neutron source strength by hand. In 2003 the SNAP III, shown in Figure 1, was designed and built. It required the operator to position the SNAP, and then measure the source-to-detector and detectorto- reflector distances. Next the operator entered the distance measurements andmore » started the data acquisition. The SNAP acquired the required count rate and then calculated and displayed the leakage neutron source strength (NSS). The original design of the SNAP III is described in SNAP III Training Manual (ER-TRN-PLN-0258, Rev. 0, January 2004, prepared by William Baird) This report describes some changes that have been made to the SNAP III. One important change is the addition of a LEMO connector to provide neutron detection output pulses for input to the MC-15. This feature is useful in active interrogation with a neutron generator because the MC-15 has the capability to only record data when it is not gated off by a pulse from the neutron generator. This avoids recording of a lot of data during the generator pulses that are not useful. Another change was the replacement of the infrared RS-232 serial communication output by a similar output via a 4-pin LEMO connector. The current document includes a more complete explanation of how to estimate the amount of moderation around a neutron-emitting source.« less

Quantitative description and local structures of trivalent metal ions Eu(III) and Cm(III) complexed with polyacrylic acid.

PubMed

Montavon, G; Bouby, M; Huclier-Markai, S; Grambow, B; Geckeis, H; Rabung, T; Pashalidis, I; Amekraz, B; Moulin, C

2008-11-15

The trivalent metal ion (M(III)=Cm, Eu)/polyacrylic acid (PAA) system was studied in the pH range between 3 and 5.5 for a molar PAA-to-metal ratio above 1. The interaction was studied for a wide range of PAA (0.05 mg L(-1)-50 g L(-1)) and metal ion concentrations (2x10(-9)-10(-3) M). This work aimed at 3 goals (i) to determine the stoichiometry of M(III)-PAA complexes, (ii) to determine the number of complexed species and the local environment of the metal ion, and (iii) to quantify the reaction processes. Asymmetric flow-field-flow fractionation (AsFlFFF) coupled to ICP-MS evidenced that size distributions of Eu-PAA complexes and PAA were identical, suggesting that Eu bound to only one PAA chain. Time-resolved laser fluorescence spectroscopy (TRLFS) measurements performed with Eu and Cm showed a continuous shift of the spectra with increasing pH. The environment of complexed metal ions obviously changes with pH. Most probably, spectral variations arose from conformational changes within the M(III)-PAA complex due to pH variation. Complexation data describing the distribution of complexed and free metal ion were measured with Cm by TRLFS. They could be quantitatively described in the whole pH-range studied by considering the existence of only a single complexed species. This indicates that the slight changes in M(III) speciation with pH observed at the molecular level do not significantly affect the intrinsic binding constant. The interaction constant obtained from the modelling must be considered as a mean interaction constant.

Nucleation and initial radius of self-catalyzed III-V nanowires

NASA Astrophysics Data System (ADS)

Dubrovskii, V. G.; Borie, S.; Dagnet, T.; Reynes, L.; André, Y.; Gil, E.

2017-02-01

We treat theoretically the initial nucleation step of self-catalyzed III-V nanowires under simultaneously deposited group III and V vapor fluxes and with surface diffusion of a group III element. Our model is capable of describing the droplet size at which the very first nanowire monolayer nucleates depending on the element fluxes and surface temperature. This size determines the initial nanowire radius in growth techniques without pre-deposition of gallium. We show that useful self-catalyzed III-V nanowires can form only under the appropriately balanced V/III flux ratios and temperatures. Such balance is required to obtain nucleation from reasonably sized droplets that are neither too small under excessive arsenic flux nor too large in the arsenic-poor conditions.

MBE growth technology for high quality strained III-V layers

NASA Technical Reports Server (NTRS)

Grunthaner, Frank J. (Inventor); Liu, John K. (Inventor); Hancock, Bruce R. (Inventor)

1990-01-01

The III-V films are grown on large automatically perfect terraces of III-V substrates which have a different lattice constant, with temperature and Group III and V arrival rates chosen to give a Group III element stable surface. The growth is pulsed to inhibit Group III metal accumulation of low temperature, and to permit the film to relax to equilibrium. The method of the invention: (1) minimizes starting step density on sample surface; (2) deposits InAs and GaAs using an interrupted growth mode (0.25 to 2 monolayers at a time); (3) maintains the instantaneous surface stoichiometry during growth (As-stable for GaAs, In-stable for InAs); and (4) uses time-resolved RHEED to achieve aspects (1) through (3).

Chromium(III), insoluble salts

Integrated Risk Information System (IRIS)

Chromium ( III ) , insoluble salts ; CASRN 16065 - 83 - 1 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments

The DSM-III personality disorders section: a commentary.

PubMed

Frances, A

1980-09-01

The author reviews the DSM-III section on personality disorders, discusses several of its more controversial diagnoses, and suggests some possible alternatives. He attributes the continued low reliability of personality diagnoses, compared with the other major sections of DSM-III, to two inherent obstacles: the lack of clear boundaries demarcating the personality disorders from normality and from one another, and the confounding influence of state and role factors. Nonetheless, the DSM-III multiaxial system highlights the importance of personality diagnosis and, together with the provision of clearly specified diagnostic criteria, achieves a considerably improved reliability compared with previous nomenclatures.

Determination of Chromium(III), Chromium(VI), and Chromium(III) acetylacetonate in water by ion-exchange disk extraction/metal furnace atomic absorption spectrometry

NASA Astrophysics Data System (ADS)

Kamakura, Nao; Inui, Tetsuo; Kitano, Masaru; Nakamura, Toshihiro

A new method for the separate determination of Chromium(III) (Cr(III)), Chromium(VI) (Cr(VI)), and Cr(III) acetylacetonate (Cr(acac)3) in water was developed using a cation-exchange extraction disk (CED) and an anion-exchange extraction disk (AED) combined with metal furnace atomic absorption spectrometry (MFAAS). A 100-mL water sample was adjusted to pH 5.6 and passed through the CED placed on the AED. Cr(acac)3 and Cr(III) were adsorbed on the CED, and Cr(VI) was adsorbed on the AED. The adsorbed Cr(acac)3 was eluted with 50 mL of carbon tetrachloride, followed by the elution of Cr(III) with 50 mL of 3 mol L- 1 nitric acid. Cr(VI) was eluted with 50 mL of 3 mol L- 1 nitric acid. The chemical species of Cr eluted from the CED with carbon tetrachloride was identified as Cr(acac)3 using infrared spectroscopy. The eluate of Cr(acac)3 was diluted to 100 mL with carbon tetrachloride, and those of Cr(III) and Cr(VI) were diluted to 100 mL with deionized water. All of the solutions were subsequently analyzed by MFAAS. The calibration curve for the Cr(acac)3 aqueous solutions exhibited good linearity in the range of 0.1 to 1 ng. The detection limit of Cr, which corresponded to three times the standard deviation (n = 10) of the blank values, was 20 pg. The recovery test for Cr(III), Cr(VI), and Cr(acac)3 exhibited desirable results (96.0%-107%) when 5 μg of each species (50 μg L- 1) was added to 100 mL water samples (i.e., tap water, rainwater, and bottled drinking water). In a humic acid solution, Cr(acac)3 was quantitatively recovered (103%), but Cr(III) and Cr(VI) exhibited poor recoveries (i.e., 84.8% and 78.4%, respectively).

A heptadecanuclear Mn(III)9Dy(III)8 cluster derived from triethanolamine with two edge sharing supertetrahedra as the core and displaying SMM behaviour.

PubMed

Langley, Stuart K; Moubarakia, Boujemaa; Murray, Keith S

2010-06-07

A heterometallic, heptadecanuclear cluster of formula [Mn(III)9Dy(III)8O8(OH)8(tea)2(teaH)2(teaH2)4(Ac)4(NO3)2(H2O)4](NO3)7·8H2O (1) is reported. The core of 1 displays two edge sharing Mn(III)5Dy(III)5 supertetrahedra and represents one of the largest Mn/4f cluster compound so far reported. Magnetic studies show that 1 displays probable SMM behaviour as observed via non-zero values in the χM''vs T plot.

Applying Resource Utilization Groups (RUG-III) in Hong Kong Nursing Homes

ERIC Educational Resources Information Center

Chou, Kee-Lee; Chi, Iris; Leung, Joe C. B.

2008-01-01

Resource Utilization Groups III (RUG-III) is a case-mix system developed in the United States for categorization of nursing home residents and the financing of residential care services. In Hong Kong, RUG-III is based on several board groups of residents. The aim of this study was to examine the reliability and validity of the RUG-III in Hong Kong…

Defects and oxidation of group-III monochalcogenide monolayers

NASA Astrophysics Data System (ADS)

Guo, Yu; Zhou, Si; Bai, Yizhen; Zhao, Jijun

2017-09-01

Among various two-dimensional (2D) materials, monolayer group-III monochalcogenides (GaS, GaSe, InS, and InSe) stand out owing to their potential applications in microelectronics and optoelectronics. Devices made of these novel 2D materials are sensitive to environmental gases, especially O2 molecules. To address this critical issue, here we systematically investigate the oxidization behaviors of perfect and defective group-III monochalcogenide monolayers by first-principles calculations. The perfect monolayers show superior oxidation resistance with large barriers of 3.02-3.20 eV for the dissociation and chemisorption of O2 molecules. In contrast, the defective monolayers with single chalcogen vacancy are vulnerable to O2, showing small barriers of only 0.26-0.36 eV for the chemisorption of an O2 molecule. Interestingly, filling an O2 molecule to the chalcogen vacancy of group-III monochalcogenide monolayers could preserve the electronic band structure of the perfect system—the bandgaps are almost intact and the carrier effective masses are only moderately disturbed. On the other hand, the defective monolayers with single vacancies of group-III atoms carry local magnetic moments of 1-2 μB. These results help experimental design and synthesis of group-III monochalcogenides based 2D devices with high performance and stability.

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. ©2015 American Association for Cancer Research.

Baseline metal enrichment from Population III star formation in cosmological volume simulations

NASA Astrophysics Data System (ADS)

Jaacks, Jason; Thompson, Robert; Finkelstein, Steven L.; Bromm, Volker

2018-04-01

We utilize the hydrodynamic and N-body code GIZMO coupled with our newly developed sub-grid Population III (Pop III) Legacy model, designed specifically for cosmological volume simulations, to study the baseline metal enrichment from Pop III star formation at z > 7. In this idealized numerical experiment, we only consider Pop III star formation. We find that our model Pop III star formation rate density (SFRD), which peaks at ˜ 10- 3 M⊙ yr- 1 Mpc- 1 near z ˜ 10, agrees well with previous numerical studies and is consistent with the observed estimates for Pop II SFRDs. The mean Pop III metallicity rises smoothly from z = 25 to 7, but does not reach the critical metallicity value, Zcrit = 10-4 Z⊙, required for the Pop III to Pop II transition in star formation mode until z ≃ 7. This suggests that, while individual haloes can suppress in situ Pop III star formation, the external enrichment is insufficient to globally terminate Pop III star formation. The maximum enrichment from Pop III star formation in star-forming dark matter haloes is Z ˜ 10-2 Z⊙, whereas the minimum found in externally enriched haloes is Z ≳ 10-7 Z⊙. Finally, mock observations of our simulated IGM enriched with Pop III metals produce equivalent widths similar to observations of an extremely metal-poor damped Lyman alpha system at z = 7.04, which is thought to be enriched by Pop III star formation only.

Molecular architectures of benzoic acid-specific type III polyketide synthases

PubMed Central

Stewart, Charles; Woods, Kate; Macias, Greg; Allan, Andrew C.; Noel, Joseph P.

2017-01-01

Biphenyl synthase and benzophenone synthase constitute an evolutionarily distinct clade of type III polyketide synthases (PKSs) that use benzoic acid-derived substrates to produce defense metabolites in plants. The use of benzoyl-CoA as an endogenous substrate is unusual for type III PKSs. Moreover, sequence analyses indicate that the residues responsible for the functional diversification of type III PKSs are mutated in benzoic acid-specific type III PKSs. In order to gain a better understanding of structure–function relationships within the type III PKS family, the crystal structures of biphenyl synthase from Malus × domestica and benzophenone synthase from Hypericum androsaemum were compared with the structure of an archetypal type III PKS: chalcone synthase from Malus × domestica. Both biphenyl synthase and benzophenone synthase contain mutations that reshape their active-site cavities to prevent the binding of 4-coumaroyl-CoA and to favor the binding of small hydrophobic substrates. The active-site cavities of biphenyl synthase and benzophenone synthase also contain a novel pocket associated with their chain-elongation and cyclization reactions. Collectively, these results illuminate structural determinants of benzoic acid-specific type III PKSs and expand the understanding of the evolution of specialized metabolic pathways in plants. PMID:29199980

Nucleosome Positioning and NDR Structure at RNA Polymerase III Promoters

NASA Astrophysics Data System (ADS)

Helbo, Alexandra Søgaard; Lay, Fides D.; Jones, Peter A.; Liang, Gangning; Grønbæk, Kirsten

2017-02-01

Chromatin is structurally involved in the transcriptional regulation of all genes. While the nucleosome positioning at RNA polymerase II (pol II) promoters has been extensively studied, less is known about the chromatin structure at pol III promoters in human cells. We use a high-resolution analysis to show substantial differences in chromatin structure of pol II and pol III promoters, and between subtypes of pol III genes. Notably, the nucleosome depleted region at the transcription start site of pol III genes extends past the termination sequences, resulting in nucleosome free gene bodies. The +1 nucleosome is located further downstream than at pol II genes and furthermore displays weak positioning. The variable position of the +1 location is seen not only within individual cell populations and between cell types, but also between different pol III promoter subtypes, suggesting that the +1 nucleosome may be involved in the transcriptional regulation of pol III genes. We find that expression and DNA methylation patterns correlate with distinct accessibility patterns, where DNA methylation associates with the silencing and inaccessibility at promoters. Taken together, this study provides the first high-resolution map of nucleosome positioning and occupancy at human pol III promoters at specific loci and genome wide.

Galleria mellonella apolipophorin III - an apolipoprotein with anti-Legionella pneumophila activity.

PubMed

Zdybicka-Barabas, Agnieszka; Palusińska-Szysz, Marta; Gruszecki, Wiesław I; Mak, Paweł; Cytryńska, Małgorzata

2014-10-01

The greater wax moth Galleria mellonella has been exploited worldwide as an alternative model host for studying pathogenicity and virulence factors of different pathogens, including Legionella pneumophila, a causative agent of a severe form of pneumonia called Legionnaires' disease. An important role in the insect immune response against invading pathogens is played by apolipophorin III (apoLp-III), a lipid- and pathogen associated molecular pattern-binding protein able to inhibit growth of some Gram-negative bacteria, including Legionella dumoffii. In the present study, anti-L. pneumophila activity of G. mellonella apoLp-III and the effects of the interaction of this protein with L. pneumophila cells are demonstrated. Alterations in the bacteria cell surface occurring upon apoLp-III treatment, revealed by Fourier transform infrared (FTIR) spectroscopy and atomic force microscopy, are also documented. ApoLp-III interactions with purified L. pneumophila LPS, an essential virulence factor of the bacteria, were analysed using electrophoresis and immunoblotting with anti-apoLp-III antibodies. Moreover, FTIR spectroscopy was used to gain detailed information on the type of conformational changes in L. pneumophila LPS and G. mellonella apoLp-III induced by their mutual interactions. The results indicate that apoLp-III binding to components of bacterial cell envelope, including LPS, may be responsible for anti-L. pneumophila activity of G. mellonella apoLp-III. Copyright © 2014 Elsevier B.V. All rights reserved.

Reduction of Fe(III) colloids by Shewanella putrefaciens: A kinetic model

NASA Astrophysics Data System (ADS)

Bonneville, Steeve; Behrends, Thilo; van Cappellen, Philippe; Hyacinthe, Christelle; Röling, Wilfred F. M.

2006-12-01

A kinetic model for the microbial reduction of Fe(III) oxyhydroxide colloids in the presence of excess electron donor is presented. The model assumes a two-step mechanism: (1) attachment of Fe(III) colloids to the cell surface and (2) reduction of Fe(III) centers at the surface of attached colloids. The validity of the model is tested using Shewanella putrefaciens and nanohematite as model dissimilatory iron reducing bacteria and Fe(III) colloidal particles, respectively. Attachment of nanohematite to the bacteria is formally described by a Langmuir isotherm. Initial iron reduction rates are shown to correlate linearly with the relative coverage of the cell surface by nanohematite particles, hence supporting a direct electron transfer from membrane-bound reductases to mineral particles attached to the cells. Using internally consistent parameter values for the maximum attachment capacity of Fe(III) colloids to the cells, Mmax, the attachment constant, KP, and the first-order Fe(III) reduction rate constant, k, the model reproduces the initial reduction rates of a variety of fine-grained Fe(III) oxyhydroxides by S. putrefaciens. The model explains the observed dependency of the apparent Fe(III) half-saturation constant, Km∗, on the solid to cell ratio, and it predicts that initial iron reduction rates exhibit saturation with respect to both the cell density and the abundance of the Fe(III) oxyhydroxide substrate.

Electronic Biosensors Based on III-Nitride Semiconductors.

PubMed

Kirste, Ronny; Rohrbaugh, Nathaniel; Bryan, Isaac; Bryan, Zachary; Collazo, Ramon; Ivanisevic, Albena

2015-01-01

We review recent advances of AlGaN/GaN high-electron-mobility transistor (HEMT)-based electronic biosensors. We discuss properties and fabrication of III-nitride-based biosensors. Because of their superior biocompatibility and aqueous stability, GaN-based devices are ready to be implemented as next-generation biosensors. We review surface properties, cleaning, and passivation as well as different pathways toward functionalization, and critically analyze III-nitride-based biosensors demonstrated in the literature, including those detecting DNA, bacteria, cancer antibodies, and toxins. We also discuss the high potential of these biosensors for monitoring living cardiac, fibroblast, and nerve cells. Finally, we report on current developments of covalent chemical functionalization of III-nitride devices. Our review concludes with a short outlook on future challenges and projected implementation directions of GaN-based HEMT biosensors.

Nearest neighbor: The low-mass Milky Way satellite Tucana III

DOE PAGES

Simon, J. D.; Li, T. S.; Drlica-Wagner, A.; ...

2017-03-17

Here, we present Magellan/IMACS spectroscopy of the recently discovered Milky Way satellite Tucana III (Tuc III). We identify 26 member stars in Tuc III from which we measure a mean radial velocity of v hel = -102.3 ± 0.4 (stat.) ± 2.0 (sys.)more » $$\\mathrm{km}\\,{{\\rm{s}}}^{-1}$$, a velocity dispersion of $${0.1}_{-0.1}^{+0.7}$$ $$\\mathrm{km}\\,{{\\rm{s}}}^{-1}$$, and a mean metallicity of $${\\rm{[Fe/H]}}=-{2.42}_{-0.08}^{+0.07}$$. The upper limit on the velocity dispersion is σ < 1.5 $$\\mathrm{km}\\,{{\\rm{s}}}^{-1}$$ at 95.5% confidence, and the corresponding upper limit on the mass within the half-light radius of Tuc III is 9.0 × 10 4 M ⊙. We cannot rule out mass-to-light ratios as large as 240 M ⊙/L ⊙ for Tuc III, but much lower mass-to-light ratios that would leave the system baryon-dominated are also allowed. We measure an upper limit on the metallicity spread of the stars in Tuc III of 0.19 dex at 95.5% confidence. Tuc III has a smaller metallicity dispersion and likely a smaller velocity dispersion than any known dwarf galaxy, but a larger size and lower surface brightness than any known globular cluster. Its metallicity is also much lower than those of the clusters with similar luminosity. We therefore tentatively suggest that Tuc III is the tidally stripped remnant of a dark matter-dominated dwarf galaxy, but additional precise velocity and metallicity measurements will be necessary for a definitive classification. If Tuc III is indeed a dwarf galaxy, it is one of the closest external galaxies to the Sun. Because of its proximity, the most luminous stars in Tuc III are quite bright, including one star at V = 15.7 that is the brightest known member star of an ultra-faint satellite.« less

Teaching DSM-III to clinicians. Some problems of the DSM-III system reducing reliability, using the diagnosis and classification of depressive disorders as an example.

PubMed

Malt, U F

1986-01-01

Experiences from teaching DSM-III to more than three hundred Norwegian psychiatrists and clinical psychologists suggest that reliable DSM-III diagnoses can be achieved within a few hours training with reference to the decision trees and the diagnostic criteria only. The diagnoses provided are more reliable than the corresponding ICD diagnoses which the participants were more familiar with. The three main sources of reduced reliability of the DSM-III diagnoses are related to: poor knowledge of the criteria which often is connected with failure of obtaining diagnostic key information during the clinical interview; unfamiliar concepts and vague or ambiguous criteria. The two first issues are related to the quality of the teaching of DSM-III. The third source of reduced reliability reflects unsolved validity issues. By using the classification of five affective case stories as examples, these sources of diagnostic pitfalls, reducing reliability and ways to overcome these problems when teaching the DSM-III system, are discussed. It is concluded that the DSM-III system of classification is easy to teach and that the system is superior to other classification systems available from a reliability point of view. The current version of the DSM-III system, however, partly owes a high degree of reliability to broad and heterogeneous diagnostic categories like the concept major depression, which may have questionable validity. Thus, the future revisions of the DSM-III system should, above all, address the issue of validity.

Etiology of AIDS: biological and biochemical characteristics of HTLV-III.

PubMed

Markham, P D; Shaw, G M; Salahuddin, S Z; Hahn, B; Sarngadharan, M G; Gallo, R C

1985-01-01

The newly identified human HTLV-III virus, the etiologic agent for AIDS, shares many of the biological and physicochemical properties common to a family of retroviruses named human T-cell leukemia (lymphotropic) viruses, or HTLV. Because of the similarities, and because of the uniform nomenclature for human T-cell leukemia (lymphotropic) viruses adopted at the first Cold Spring Harbor Meeting on HTLV (19, 79), this newly discovered virus associated with AIDS as HTLV-III was named HTLV-III. Other investigators making independent isolations of virus have suggested naming the virus lymphadenopathy virus or LAV (3, 16), immunodeficiency associated virus or IADV (48), AIDS-related virus (41). Immunological and nucleic acid comparison has now demonstrated that these viruses are, not surprisingly, very similar to HTLV-III (55, 63, 78). In view of the wide range of disease manifestations caused by the virus, and previous discussions concerning a uniform nomenclature for human T-lymphotropic retroviruses, it would seem ill-advised to restrict the name of this virus to one clinical manifestation of one disease. The frequent isolation of HTLV-III from patients with AIDS and ARC, the detection of antibodies specific for HTLV-III in nearly all patients with these diseases and in a high proportion of individuals at risk, and finally its effect on cells in vitro, leaves little doubt that HTLV-III is causatively involved in the development of these diseases. This etiologic association is further strengthened by the detection of HTLV-III infection in many instances where a direct cause-and-effect association can be made, e.g., hemophiliacs and children with AIDS, and blood from HTLV-III infected donors and the otherwise normal recipients of this blood who subsequently develop AIDS.

25 CFR 522.7 - Disapproval of a class III ordinance.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 25 Indians 2 2010-04-01 2010-04-01 false Disapproval of a class III ordinance. 522.7 Section 522.7 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 § 522.7 Disapproval of a class III...

Intelligence or Misorientation? Eurocentrism in the WISC-III.

ERIC Educational Resources Information Center

Kwate, Naa Oyo A.

2001-01-01

Examines the Eurocentric basis of the Wechsler Intelligence Scale for Children--Third Edition (WISC-III) and reveals its antagonistic and incompatible relationship to an Africentric conception of intellectual and mental health. Suggests that the WISC-III provides a measure of misorientation quotient rather than intelligence quotient, and notes…

Comparative study on Ce (III) and La (III) solvent extraction and separation from a nitric acid medium by D2EHPA and Cyanex272

NASA Astrophysics Data System (ADS)

Habibpour, R.; Dargahi, M.; Kashi, E.; Bagherpour, M.

2018-01-01

The solvent extraction of Cerium(III) and Lanthanum(III) from nitric acid solution using the organophosphorous extractants Di-(2-ethyl hexyl) phosphate (D2EHPA) and di-2,4,4- trimethylpentyl phosphoric acid (Cyanex272) in kerosene was investigated. In this study, the magnitude of the extraction of Ce(III) was found to be more significant with Cyanex272 than D2EHPA. D2EHPA was found to be a better extractant for La(III). Among the two extractants, Cyanex272 was used for the separation of Ce from La in three stages with an extraction efficiency of 90.2% for Ce. A 556 mg/L Ce solution was used for the scrubbing of La with an efficiency of ≈34%, which required multi stage scrubbing. The study of thermodynamic parameters such as enthalpy, entropy, and Gibbs free energy impart the exothermic and non-spontaneous process. The chemical speciation curves for lanthanum and cerium in the aqueous phase as a function of pH showed that the free La(III) and Ce(III) metal ion species were largely predominate between a pH = 0 and pH = 7.

The Synthesis of 1,1’-Bicobaltocene Salts of Tetracyano-P-Quinodimethanide and the Sturcture of 1,1’-Bicobaltocene (Co (III) Co (III)) (TCNQ)3,

DTIC Science & Technology

1981-06-03

Salts of Bicobaltocenet-The hexafluorophosphate salt of bicobaltocene(III,III) was prepared by the method of Davison and Smart 4 and the orange product...tetrahydrofuran. The lithium salt of TCNO was prepared by adding a boiling solution of lithium iodide in acetonitrile to a boiling solution of TCNQ in...compound 1,1’-bicobaltocene[Co(III)Co(III)[TCNQJ 3 resulted from the reaction of the mixed valence hexafluorophosphate salt with a mixture of [Et3NH

Isolation and Characterization of a Dihydroxo-Bridged Iron(III,III)(μ-OH)2 Diamond Core Derived from Dioxygen

PubMed Central

Coggins, Michael K.; Toledo, Santiago; Kovacs, Julie A.

2013-01-01

Dioxygen addition to coordinatively unsaturated [Fe(II)(OMe2N4(6-Me-DPEN))](PF6) (1) is shown to afford a complex containing a dihydroxo-bridged Fe(III)2(μ-OH)2 diamond core, [FeIII(OMe2N4(6-Me-DPEN))]2(μ-OH)2(PF6)2•(CH3CH2CN)2 (2). The diamond core of 2 resembles the oxidized methane monooxygenase (MMOox) resting state, as well as the active site product formed following H-atom abstraction from Tyr-OH by ribonucleotide reductase (RNR). The Fe-OH bond lengths of 2 are comparable with those of the MMOHox suggesting that MMOHox contains a Fe(III)2(μ-OH)2 as opposed to Fe(III)2(μ-OH)(μ-OH2) diamond core as had been suggested. Isotopic labeling experiments with 18O2 and CD3CN indicate that the oxygen and proton of the μ-OH bridges of 2 are derived from dioxygen and acetonitrile. Deuterium incorporation (from CD3CN) suggests that an unobserved intermediate capable of abstracting a H-atom from CH3CN forms en route to 2. Given the high C–H bond dissociation energy (BDE= 97 kcal/mol) of acetonitrile, this indicates that this intermediate is a potent oxidant, possibly a high-valent iron oxo. Consistent with this, iodosylbenzene (PhIO) also reacts with 1 in CD3CN to afford the deuterated Fe(III)2(μ-OD)2 derivative of 2. Intermediates are not spectroscopically observed in either reaction (O2 and PhIO) even at low-temperatures (−80 °C), indicating that this intermediate has a very short life-time, likely due to its highly reactive nature. Hydroxo-bridged 2 was found to stoichiometrically abstract hydrogen atoms from 9,10-dihydroanthracene (C-H BDE= 76 kcal/mol) at ambient temperatures. PMID:24229319

Phase III Early Restoration Public Meetings | NOAA Gulf Spill Restoration

Science.gov Websites

Archive Home Phase III Early Restoration Public Meetings Phase III Early Restoration Public Meetings share Posted on December 6, 2013 | Assessment and Early Restoration Restoration Area Title: Phase III Early on the draft plan for the third phase of Early Restoration, which proposes more than $625 million in

Mechanism of Ribonuclease III Catalytic Regulation by Serine Phosphorylation

NASA Astrophysics Data System (ADS)

Gone, Swapna; Alfonso-Prieto, Mercedes; Paudyal, Samridhdi; Nicholson, Allen W.

2016-05-01

Ribonuclease III (RNase III) is a conserved, gene-regulatory bacterial endonuclease that cleaves double-helical structures in diverse coding and noncoding RNAs. RNase III is subject to multiple levels of control, reflective of its global regulatory functions. Escherichia coli (Ec) RNase III catalytic activity is known to increase during bacteriophage T7 infection, reflecting the expression of the phage-encoded protein kinase, T7PK. However, the mechanism of catalytic enhancement is unknown. This study shows that Ec-RNase III is phosphorylated on serine in vitro by purified T7PK, and identifies the targets as Ser33 and Ser34 in the N-terminal catalytic domain. Kinetic experiments reveal a 5-fold increase in kcat and a 1.4-fold decrease in Km following phosphorylation, providing a 7.4-fold increase in catalytic efficiency. Phosphorylation does not change the rate of substrate cleavage under single-turnover conditions, indicating that phosphorylation enhances product release, which also is the rate-limiting step in the steady-state. Molecular dynamics simulations provide a mechanism for facilitated product release, in which the Ser33 phosphomonoester forms a salt bridge with the Arg95 guanidinium group, thereby weakening RNase III engagement of product. The simulations also show why glutamic acid substitution at either serine does not confer enhancement, thus underscoring the specific requirement for a phosphomonoester.

Oral findings in patients with mucolipidosis type III.

PubMed

Cavalcante, Weber Céo; Santos, Luciano Cincurá Silva; Dos Santos, Josiane Nascimento; de Vasconcellos, Sara Juliana de Abreu; de Azevedo, Roberto Almeida; Dos Santos, Jean Nunes

2012-01-01

Mucolipidosis type III is a rare, autosomal recessive disorder, which is part of a group of storage diseases as a result of inborn error of lysosomal enzyme metabolism. It is characterized by the gradual onset of signs and symptoms affecting the physical and mental development as well as visual changes, heart, skeletal and joint. Although oral findings associated with mucolipidosis type II have been extensively reported, there is a shortage of information on mucolipidosis type III. This paper presents radiological and histological findings of multiple radiolucent lesions associated with impacted teeth in the jaw of a 16 year-old youngster with mucolipidosis type III.

The Stratospheric Aerosol and Gas Experiment (SAGE III)

NASA Technical Reports Server (NTRS)

Thomason, Larry W.

1998-01-01

Three SAGE III instruments are being built by Ball Aerospace & Technologies Corporation in Boulder, Colorado (USA). SAGE III is a fourth generation instrument that incorporates robust elements of its predecessors [SAM II, SAGE, SAGE II] while incorporating new design elements. The first of these will be launched aboard a Russian Meteor/3M platform in May 1999. SAGE III will add measurements of O2-A band from which density and temperature profiles are retrieved. This feature should improve refraction and Rayleigh computations over earlier. Additionally, the linear array of detectors will permit on-orbit wavelength calibration from observations of the exo-atmospheric solar Fraunhofer spectrum.

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)

30 CFR 57.22308 - Methane monitors (III mines).

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Methane monitors (III mines). 57.22308 Section... Standards for Methane in Metal and Nonmetal Mines Equipment § 57.22308 Methane monitors (III mines). (a) Methane monitors shall be installed on continuous mining machines and longwall mining systems. (b) The...

30 CFR 57.22308 - Methane monitors (III mines).

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Methane monitors (III mines). 57.22308 Section... Standards for Methane in Metal and Nonmetal Mines Equipment § 57.22308 Methane monitors (III mines). (a) Methane monitors shall be installed on continuous mining machines and longwall mining systems. (b) The...

Key differences between apoC-III regulation and expression in intestine and liver.

PubMed

West, Gabrielle; Rodia, Cayla; Li, Diana; Johnson, Zania; Dong, Hongli; Kohan, Alison B

2017-09-23

ApoC-III is a critical cardiovascular risk factor, and humans expressing null mutations in apoC-III are robustly protected from cardiovascular disease. Because of its critical role in elevating plasma lipids and CVD risk, hepatic apoC-III regulation has been studied at length. Considerably less is known about the factors that regulate intestinal apoC-III. In this work, we use primary murine enteroids, Caco-2 cells, and dietary studies in wild-type mice to show that intestinal apoC-III expression does not change in response to fatty acids, glucose, or insulin administration, in contrast to hepatic apoC-III. Intestinal apoC-III is not sensitive to changes in FoxO1 expression (which is itself very low in the intestine, as is FoxO1 target IGFBP-1), nor is intestinal apoC-III responsive to western diet, a significant contrast to hepatic apoC-III stimulation during western diet. These data strongly suggest that intestinal apoC-III is not a FoxO1 target and support the idea that apoC-III is not regulated coordinately with hepatic apoC-III, and establishes another key aspect of apoC-III that is unique in the intestine from the liver. Copyright © 2017 Elsevier Inc. All rights reserved.

Theranostic Gd(III)-lipid microbubbles for MRI-guided focused ultrasound surgery.

PubMed

Feshitan, Jameel A; Vlachos, Fotis; Sirsi, Shashank R; Konofagou, Elisa E; Borden, Mark A

2012-01-01

We have synthesized a biomaterial consisting of Gd(III) ions chelated to lipid-coated, size-selected microbubbles for utility in both magnetic resonance and ultrasound imaging. The macrocyclic ligand DOTA-NHS was bound to PE headgroups on the lipid shell of pre-synthesized microbubbles. Gd(III) was then chelated to DOTA on the microbubble shell. The reaction temperature was optimized to increase the rate of Gd(III) chelation while maintaining microbubble stability. ICP-OES analysis of the microbubbles determined a surface density of 7.5 × 10(5) ± 3.0 × 10(5) Gd(III)/μm(2) after chelation at 50 °C. The Gd(III)-bound microbubbles were found to be echogenic in vivo during high-frequency ultrasound imaging of the mouse kidney. The Gd(III)-bound microbubbles also were characterized by magnetic resonance imaging (MRI) at 9.4 T by a spin-echo technique and, surprisingly, both the longitudinal and transverse proton relaxation rates were found to be roughly equal to that of no-Gd(III) control microbubbles and saline. However, the relaxation rates increased significantly, and in a dose-dependent manner, after sonication was used to fragment the Gd(III)-bound microbubbles into non-gas-containing lipid bilayer remnants. The longitudinal (r(1)) and transverse (r(2)) molar relaxivities were 4.0 ± 0.4 and 120 ± 18 mM(-1)s(-1), respectively, based on Gd(III) content. The Gd(III)-bound microbubbles may find application in the measurement of cavitation events during MRI-guided focused ultrasound therapy and to track the biodistribution of shell remnants. Copyright © 2011 Elsevier Ltd. All rights reserved.

Photofunctional triplet excited states of cyclometalated Ir(III) complexes: beyond electroluminescence.

PubMed

You, Youngmin; Nam, Wonwoo

2012-11-07

The development of cyclometalated Ir(III) complexes has enabled important breakthroughs in electroluminescence because such complexes permit the efficient population of triplet excited states that give rise to luminescent transitions. The triplet states of Ir(III) complexes are advantageous over those of other transition metal complexes in that their electronic transitions and charge-transfer characteristics are tunable over wide ranges. These favorable properties suggest that Ir(III) complexes have significant potential in a variety of photofunctions other than electroluminescence. In this critical review, we describe recent photonic applications of novel Ir(III) complexes. Ir(III) complexes have been shown to affect the exciton statistics in the active layers of organic photovoltaic cells, thereby improving the photon-to-current conversion efficiencies. Nonlinear optical applications that take advantage of the strong charge-transfer properties of triplet transitions are also discussed. The tunability of the electrochemical potentials facilitates the development of efficient photocatalysis in the context of water photolysis or organic syntheses. The photoredox reactivities of Ir(III) complexes have been employed in studies of charge migration along DNA chains. The photoinduced cytotoxicity of Ir(III) complexes on live cells suggests that the complexes may be useful in photodynamic therapy. Potential biological applications of the complexes include phosphorescence labeling and sensing. Intriguing platforms based on cyclometalated Ir(III) complexes potentially provide novel protein tagging and ratiometric detection. We envision that future research into the photofunctionality of Ir(III) complexes will provide important breakthroughs in a variety of photonic applications.

Head and Neck Squamous Cell Carcinomas Do Not Express EGFRvIII

DOE Office of Scientific and Technical Information (OSTI.GOV)

Melchers, Lieuwe J., E-mail: l.j.melchers@umcg.nl; Department of Pathology, University Medical Center Groningen, University of Groningen, Groningen; Clausen, Martijn J.A.M.

2014-10-01

Purpose: To assess the prevalence of EGFRvIII, a specific variant of EGFR (epidermal growth factor receptor), in 3 well-defined cohorts of head and neck squamous cell carcinoma (HNSCC). Methods and Materials: Immunohistochemistry for the specific detection of EGFRvIII using the L8A4 antibody was optimized on formalin-fixed, paraffin-embedded tissue using glioblastoma tissue. It was compared with EGFR and EGFRvIII RNA expression using a specific reverse transcription–polymerase chain reaction also optimized for formalin-fixed, paraffin-embedded tissue. Tissue microarrays including 531 HNSCCs of various stages with complete clinicopathologic and follow-up data were tested for the presence of EGFRvIII. Results: None of the 531 casesmore » showed EGFRvIII protein expression. Using an immunohistochemistry protocol reported by others revealed cytoplasmic staining in 8% of cases. Reverse transcription–polymerase chain reaction for the EGFRvIII transcript of the 28 highest cytoplasmic staining cases, as well as 69 negative cases, did not show expression in any of the tested cases, suggesting aspecific staining by a nonoptimal protocol. Conclusions: The EGFRvIII mutation is not present in HNSCC. Therefore, EGFRvIII does not influence treatment response in HNSCC and is not a usable clinical prognostic marker.« less

Me-3,2-HOPO Complexes of Near Infra-Red (NIR) Emitting Lanthanides: Efficient Sensitization of Yb(III) and Nd(III) in Aqueous Solution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moore, Evan G.; Xu, Jide; Dodani, Sheel

2009-11-10

The synthesis, X-ray structure, solution stability, and photophysical properties of several trivalent lanthanide complexes of Yb(III) and Nd(III) using both tetradentate and octadentate ligand design strategies and incorporating the 1-methyl-3-hydroxy-pyridin-2-one (Me-3,2-HOPO) chelate group are reported. Both the Yb(III) and Nd(III) complexes have emission bands in the Near Infra-Red (NIR) region, and this luminescence is retained in aqueous solution ({Phi}{sub tot}{sup Yb} {approx} 0.09-0.22%). Furthermore, the complexes demonstrate very high stability (pYb {approx} 18.8-21.9) in aqueous solution, making them good candidates for further development as probes for NIR imaging. Analysis of the low temperature (77 K) photophysical measurements for a modelmore » Gd(III) complex were used to gain an insight into the electronic structure, and were found to agree well with corresponding TD-DFT calculations at the B3LYP/6-311G{sup ++}(d,p) level of theory for a simplified model monovalent sodium complex.« less

A well-defined terminal vanadium(III) oxo complex.

PubMed

King, Amanda E; Nippe, Michael; Atanasov, Mihail; Chantarojsiri, Teera; Wray, Curtis A; Bill, Eckhard; Neese, Frank; Long, Jeffrey R; Chang, Christopher J

2014-11-03

The ubiquity of vanadium oxo complexes in the V+ and IV+ oxidation states has contributed to a comprehensive understanding of their electronic structure and reactivity. However, despite being predicted to be stable by ligand-field theory, the isolation and characterization of a well-defined terminal mononuclear vanadium(III) oxo complex has remained elusive. We present the synthesis and characterization of a unique terminal mononuclear vanadium(III) oxo species supported by the pentadentate polypyridyl ligand 2,6-bis[1,1-bis(2-pyridyl)ethyl]pyridine (PY5Me2). Exposure of [V(II)(NCCH3)(PY5Me2)](2+) (1) to either dioxygen or selected O-atom-transfer reagents yields [V(IV)(O)(PY5Me2)](2+) (2). The metal-centered one-electron reduction of this vanadium(IV) oxo complex furnishes a stable, diamagnetic [V(III)(O)(PY5Me2)](+) (3) species. The vanadium(III) oxo species is unreactive toward H- and O-atom transfer but readily reacts with protons to form a putative vanadium hydroxo complex. Computational results predict that further one-electron reduction of the vanadium(III) oxo species will result in ligand-based reduction, even though pyridine is generally considered to be a poor π-accepting ligand. These results have implications for future efforts toward low-valent vanadyl chemistry, particularly with regard to the isolation and study of formal vanadium(II) oxo species.

[Diagnostic values of type III Procollagen N-terminal peptide and combination assay of type III procollagen N-terminal peptide with CEA and CA 19-9 in gastric cancer].

PubMed

Akazawa, S; Harada, A; Futatsuki, K

1984-07-01

It is known that interstitial collagens are initially synthesized as precursors (procollagen), which possess extra peptide segments at both ends of the molecules. The authors attempted to detect the aminoterminal peptide of type III procollagen (type III-N-peptide) and also to measure the carcinoembryonic antigen (CEA) and carbohydrate antigen (CA 19-9) together in sera of patients with gastric cancer. The results showed that: (1) mean serum levels and positive ratios of the type III-N-peptide increased as the clinical stage of the patients with gastric cancer advanced; (2) serum levels of the type III-N-peptide were not correlated either with those of CEA or CA 19-9; (3) positive ratios of type III-N-peptide, CEA and CA 19-9 were 51.7%, 44.8% and 48.3%, respectively: (4) positive ratio in combination of the type III-N-peptide with CEA was 69.3% and that in combination of the type III-N-peptide with CEA and CA 19-9 was 72.4%. These results suggest that type III-N-peptide is available for diagnosis of gastric cancer and, that the combination assay of type III-N-peptide with CEA and CA 19-9 is more effective than a single assay for diagnosis.

Mitochondria are the main target organelle for trivalent monomethylarsonous acid (MMA(III))-induced cytotoxicity.

PubMed

Naranmandura, Hua; Xu, Shi; Sawata, Takashi; Hao, Wen Hui; Liu, Huan; Bu, Na; Ogra, Yasumitsu; Lou, Yi Jia; Suzuki, Noriyuki

2011-07-18

Excessive generation of reactive oxygen species (ROS) is considered to play an important role in arsenic-induced carcinogenicity in the liver, lungs, and urinary bladder. However, little is known about the mechanism of ROS-based carcinogenicity, including where the ROS are generated, and which arsenic species are the most effective ROS inducers. In order to better understand the mechanism of arsenic toxicity, rat liver RLC-16 cells were exposed to arsenite (iAs(III)) and its intermediate metabolites [i.e., monomethylarsonous acid (MMA(III)) and dimethylarsinous acid (DMA(III))]. MMA(III) (IC(50) = 1 μM) was found to be the most toxic form, followed by DMA(III) (IC(50) = 2 μM) and iAs(III) (IC(50) = 18 μM). Following exposure to MMA(III), ROS were found to be generated primarily in the mitochondria. DMA(III) exposure resulted in ROS generation in other organelles, while no ROS generation was seen following exposures to low levels of iAs(III). This suggests the mechanisms of induction of ROS are different among the three arsenicals. The effects of iAs(III), MMA(III), and DMA(III) on activities of complexes I-IV in the electron transport chain (ETC) of rat liver submitochondrial particles and on the stimulation of ROS production in intact mitochondria were also studied. Activities of complexes II and IV were significantly inhibited by MMA(III), but only the activity of complexes II was inhibited by DMA(III). Incubation with iAs(III) had no inhibitory effects on any of the four complexes. Generation of ROS in intact mitochondria was significantly increased following incubation with MMA(III), while low levels of ROS generation were observed following incubation with DMA(III). ROS was not produced in mitochondria following exposure to iAs(III). The mechanism underlying cell death is different among As(III), MMA(III), and DMA(III), with mitochondria being one of the primary target organelles for MMA(III)-induced cytotoxicity. © 2011 American Chemical Society

Fusion protein of retinol-binding protein and albumin domain III reduces liver fibrosis

PubMed Central

Lee, Hongsik; Jeong, Hyeyeun; Park, Sangeun; Yoo, Wonbaek; Choi, Soyoung; Choi, Kyungmin; Lee, Min-Goo; Lee, Mihwa; Cha, DaeRyong; Kim, Young-Sik; Han, Jeeyoung; Kim, Wonkon; Park, Sun-Hwa; Oh, Junseo

2015-01-01

Activated hepatic stellate cells (HSCs) play a key role in liver fibrosis, and inactivating HSCs has been considered a promising therapeutic approach. We previously showed that albumin and its derivative designed for stellate cell-targeting, retinol-binding protein–albumin domain III fusion protein (referred to as R-III), inactivate cultured HSCs. Here, we investigated the mechanism of action of albumin/R-III in HSCs and examined the anti-fibrotic potential of R-III in vivo. R-III treatment and albumin expression downregulated retinoic acid (RA) signaling which was involved in HSC activation. RA receptor agonist and retinaldehyde dehydrogenase overexpression abolished the anti-fibrotic effect of R-III and albumin, respectively. R-III uptake into cultured HSCs was significantly decreased by siRNA-STRA6, and injected R-III was localized predominantly in HSCs in liver. Importantly, R-III administration reduced CCl4- and bile duct ligation-induced liver fibrosis. R-III also exhibited a preventive effect against CCl4-inducd liver fibrosis. These findings suggest that the anti-fibrotic effect of albumin/R-III is, at least in part, mediated by downregulation of RA signaling and that R-III is a good candidate as a novel anti-fibrotic drug. PMID:25864124

Co(III) as mediator in phenol destruction using electrochemical oxidation

NASA Astrophysics Data System (ADS)

Herlina, Herlina; Derlini, Derlini; Muhammad, Razali

2017-03-01

Mediated electrochemical oxidation is one of the method for oxidation of organic compound by using a mediator. This method has been developed because have several advantages which low cost and efficient, the exhaust gas does not contain toxic materials and hazardous waste and the process take place at a relatively low temperature. Electrochemical oxidation of organic compounds using metal ion mediator is one alternative method that is appropriate for the treatment of organic waste. Co(III) is a strong oxidizing agent used as a mediator has been prepared in Pt electrodes. The concentration of Co(III) formed during oxidation determined by potentiometric titration where Co(III) aliquot was added into Fe(II) excess solution and the remaining Fe(II) which did not react has been titrated with Ce(IV). In optimum condition, Co(III) was then used to oxidize the organic compound into carbon dioxide. The parameters has been studied are the standard oxidation potential of mediator, acid concentration and temperature. The results obtained at potential of 6 Volt, with nitric acid 4 M and temperature of 25°C give result 23.86% where Co (II) is converted to Co(III) within 2 hours. The addition of silver nitrate can increase the concentration of Co(III). At the optimum conditions, the mediator ion Co(III) can destructed to 66.44% of phenol compound oxidized into carbon dioxide.

Nanowire-templated lateral epitaxial growth of non-polar group III nitrides

DOEpatents

Wang, George T [Albuquerque, NM; Li, Qiming [Albuquerque, NM; Creighton, J Randall [Albuquerque, NM

2010-03-02

A method for growing high quality, nonpolar Group III nitrides using lateral growth from Group III nitride nanowires. The method of nanowire-templated lateral epitaxial growth (NTLEG) employs crystallographically aligned, substantially vertical Group III nitride nanowire arrays grown by metal-catalyzed metal-organic chemical vapor deposition (MOCVD) as templates for the lateral growth and coalescence of virtually crack-free Group III nitride films. This method requires no patterning or separate nitride growth step.

Diversity and Evolutionary History of Iron Metabolism Genes in Diatoms