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Sample records for manganese transporter bb0219

  1. Manganese transport in Brevibacterium ammoniagenes ATCC 6872.

    PubMed Central

    Schmid, J; Auling, G

    1987-01-01

    Uptake of manganese by Brevibacterium ammoniagenes ATCC 6872 was energy dependent and obeyed saturation kinetics (Km = 0.65 microM; Vmax = 0.12 mumol/min per g [dry weight]). Uptake showed optima at 27 degrees C and pH 9.5. 54Mn2+ accumulated by the cells was released by treatment with toluene or by exchange for unlabeled manganese ions, via an energy-dependent process. Co2+, Fe2+, Cd2+, and Zn2+ inhibited manganese uptake. Inhibition by Cd2+ and Zn2+ was competitive (Ki = 0.15 microM Cd2+ and 1.2 microM Zn2+). Experiments with 65Zn2+ provided no evidence for Zn2+ uptake via the Mn2+ transport system. PMID:3597325

  2. Manganese Transport via the Transferrin Mechanism

    PubMed Central

    Gunter, Thomas E.; Gerstner, Brent; Gunter, Karlene K.; Malecki, Jon; Gelein, Robert; Valentine, William M.; Aschner, Michael; Yule, David I.

    2013-01-01

    Excessive manganese (Mn) uptake by brain cells, particularly in regions like the basal ganglia, can lead to toxicity. Mn2+ is transported into cells via a number of mechanisms, while Mn3+ is believed to be transported similarly to iron (Fe) via the transferrin (Tf) mechanism. Cellular Mn uptake is therefore determined by the activity of the mechanisms transporting Mn into each type of cell and by the amounts of Mn2+, Mn3+ and their complexes to which these cells are exposed; this complicates understanding the contributions of each transporter to Mn toxicity. While uptake of Fe3+ via the Tf mechanism is well understood, uptake of Mn3+ via this mechanism has not been systematically studied. The stability of the Mn3+Tf complex allowed us to form and purify this complex and label it with a fluorescent (Alexa green) tag. Using purified and labeled Mn3+Tf and biophysical tools, we have developed a novel approach to study Mn3+Tf transport independently of other Mn transport mechanisms. This approach was used to compare the uptake of Mn3+Tf into neuronal cell lines with published descriptions of Fe3+ uptake via the Tf mechanism, and to obtain quantitative information on Mn uptake via the Tf mechanism. Results confirm that in these cell lines significant Mn3+ is transported by the Tf mechanism similarly to Fe3+Tf transport; although Mn3+Tf transport is markedly slower than other Mn transport mechanisms. This novel approach may prove useful for studying Mn toxicity in other systems and cell types. PMID:23146871

  3. Manganese

    MedlinePlus

    Manganese is a mineral that is found in several foods including nuts, legumes, seeds, tea, whole grains, and leafy green vegetables. It is ... manganese by mouth along with other vitamins and minerals can promote growth in children who have low ...

  4. Manganese: Recent advances in understanding its transport and neurotoxicity

    SciTech Connect

    Aschner, Michael . E-mail: Michael.Aschner@vanderbilt.edu; Guilarte, Tomas R.; Schneider, Jay S.; Zheng Wei

    2007-06-01

    The present review is based on presentations from the meeting of the Society of Toxicology in San Diego, CA (March 2006). It addresses recent developments in the understanding of the transport of manganese (Mn) into the central nervous system (CNS), as well as brain imaging and neurocognitive studies in non-human primates aimed at improving our understanding of the mechanisms of Mn neurotoxicity. Finally, we discuss potential therapeutic modalities for treating Mn intoxication in humans.

  5. The role of zinc transporters in cadmium and manganese transport in mammalian cells.

    PubMed

    Himeno, Seiichiro; Yanagiya, Takahiro; Fujishiro, Hitomi

    2009-10-01

    To understand the mechanism of cadmium accumulation, it is important to know the precise mechanisms of transport systems for other metals. Recently, utilization of genomics and metallomics has clarified the involvement of specific metal transporter(s) in cadmium uptake. Studies with metallothionein (MT)-null cadmium-resistant cells have revealed the involvement of the manganese/zinc transport system in cadmium uptake. Genomic studies of strain differences in sensitivity to cadmium-induced testicular hemorrhage revealed that a zinc transporter, Zrt-, Irt-related protein (ZIP) 8 encoded by slc39a8, is responsible for the strain difference. Ectopic expression of ZIP8 in various cells enhanced the uptake of cadmium, manganese, and zinc. ZIP8-transgenic mice showed high expression of ZIP8 in the vasculature of testis and apical membrane of proximal tubules in kidney, and exhibited enhanced cadmium accumulation and toxicity when treated with cadmium. The expression of ZIP8 was found to be down-regulated in MT-null cadmium-resistant cells, in which the uptake rates of both cadmium and manganese were decreased. These data suggest that ZIP8 plays an important role in the uptake of both cadmium and manganese in mammalian cells. The role of ZIP14 in the uptake of cadmium and manganese is also discussed. PMID:19375483

  6. Regulation of cellular manganese and manganese transport rates in the unicellular alga Chlamydomonas

    SciTech Connect

    Sunda, W.G.; Huntsman, S.A.

    1985-01-01

    The cellular accumulation and uptake kinetics of manganese by Chlamydomonas sp. were studied in model chelate buffer systems. Cellular manganese concentrations and uptake rates were related to the computed free manganese ion concentration and were independent of the total or chelated manganese concentration. Cellular manganese was constant at about 1 mmol liter/sup -1/ of cellular volume at free manganese ion concentrations of 10/sup -7/ /sup 6/-10/sup -6/ /sup 3/ mol liter/sup -1/ and decreased below this range. Manganese uptake rates followed saturation kinetics and V/sub max/, but not K/sub s/, varied with the free manganese ion concentration in the growth medium. V/sub max/ appeared to be under negative feedback control and increased with decreasing manganese ion concentration. Variations of up to 30-fold in this parameter seemed to be instrumental in limiting the variation in cellular manganese to a sixfold range despite a 1000-fold variation in free manganese ion concentration in the growth medium.

  7. Manganese

    MedlinePlus

    ... no RDAs for a nutrient, the Adequate Intake (AI) is used as a guide. The AI is the estimated amount of the nutrient that ... assumed to be adequate. The daily Adequate Intake (AI) levels for manganese are: infants birth to 6 ...

  8. Manganese

    Integrated Risk Information System (IRIS)

    Manganese ; CASRN 7439 - 96 - 5 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 for Noncarcinogenic Effect

  9. Characterisation of the Porphyromonas gingivalis Manganese Transport Regulator Orthologue

    PubMed Central

    Dashper, Stuart G.; Seers, Christine A.; Veith, Paul D.; Zhang, Jian-Guo; Reynolds, Eric C.

    2016-01-01

    PgMntR is a predicted member of the DtxR family of transcriptional repressors responsive to manganese in the anaerobic periodontal pathogen Porphyromonas gingivalis. Our bioinformatic analyses predicted that PgMntR had divalent metal binding site(s) with elements of both manganous and ferrous ion specificity and that PgMntR has unusual twin C-terminal FeoA domains. We produced recombinant PgMntR and four variants to probe the specificity of metal binding and its impact on protein structure and DNA binding. PgMntR dimerised in the absence of a divalent transition metal cation. PgMntR bound three Mn(II) per monomer with an overall dissociation constant Kd 2.0 x 10−11 M at pH 7.5. PgMntR also bound two Fe(II) with distinct binding affinities, Kd1 2.5 x 10−10 M and Kd2 ≤ 6.0 x 10−8 M at pH 6.8. Two of the metal binding sites may form a binuclear centre with two bound Mn2+ being bridged by Cys108 but this centre provided only one site for Fe2+. Binding of Fe2+ or Mn2+ did not have a marked effect on the PgMntR secondary structure. Apo-PgMntR had a distinct affinity for the promoter region of the gene encoding the only known P. gingivalis manganese transporter, FB2. Mn2+ increased the DNA binding affinity of PgMntR whilst Fe2+ destabilised the protein-DNA complex in vitro. PgMntR did not bind the promoter DNA of the gene encoding the characterised iron transporter FB1. The C-terminal FeoA domain was shown to be essential for PgMntR structure/function, as its removal caused the introduction of an intramolecular disulfide bond and abolished the binding of Mn2+ and DNA. These data indicate that PgMntR is a novel member of the DtxR family that may function as a transcriptional repressor switch to specifically regulate manganese transport and homeostasis in an iron-dependent manner. PMID:27007570

  10. Characterisation of the Porphyromonas gingivalis Manganese Transport Regulator Orthologue.

    PubMed

    Zhang, Lianyi; Butler, Catherine A; Khan, Hasnah S G; Dashper, Stuart G; Seers, Christine A; Veith, Paul D; Zhang, Jian-Guo; Reynolds, Eric C

    2016-01-01

    PgMntR is a predicted member of the DtxR family of transcriptional repressors responsive to manganese in the anaerobic periodontal pathogen Porphyromonas gingivalis. Our bioinformatic analyses predicted that PgMntR had divalent metal binding site(s) with elements of both manganous and ferrous ion specificity and that PgMntR has unusual twin C-terminal FeoA domains. We produced recombinant PgMntR and four variants to probe the specificity of metal binding and its impact on protein structure and DNA binding. PgMntR dimerised in the absence of a divalent transition metal cation. PgMntR bound three Mn(II) per monomer with an overall dissociation constant Kd 2.0 x 10(-11) M at pH 7.5. PgMntR also bound two Fe(II) with distinct binding affinities, Kd1 2.5 x 10(-10) M and Kd2 ≤ 6.0 x 10(-8) M at pH 6.8. Two of the metal binding sites may form a binuclear centre with two bound Mn2+ being bridged by Cys108 but this centre provided only one site for Fe2+. Binding of Fe2+ or Mn2+ did not have a marked effect on the PgMntR secondary structure. Apo-PgMntR had a distinct affinity for the promoter region of the gene encoding the only known P. gingivalis manganese transporter, FB2. Mn2+ increased the DNA binding affinity of PgMntR whilst Fe2+ destabilised the protein-DNA complex in vitro. PgMntR did not bind the promoter DNA of the gene encoding the characterised iron transporter FB1. The C-terminal FeoA domain was shown to be essential for PgMntR structure/function, as its removal caused the introduction of an intramolecular disulfide bond and abolished the binding of Mn2+ and DNA. These data indicate that PgMntR is a novel member of the DtxR family that may function as a transcriptional repressor switch to specifically regulate manganese transport and homeostasis in an iron-dependent manner. PMID:27007570

  11. Direct Comparison of Manganese Detoxification/Efflux Proteins and Molecular Characterization of ZnT10 Protein as a Manganese Transporter.

    PubMed

    Nishito, Yukina; Tsuji, Natsuko; Fujishiro, Hitomi; Takeda, Taka-Aki; Yamazaki, Tomohiro; Teranishi, Fumie; Okazaki, Fumiko; Matsunaga, Ayu; Tuschl, Karin; Rao, Rajini; Kono, Satoshi; Miyajima, Hiroaki; Narita, Hiroshi; Himeno, Seiichiro; Kambe, Taiho

    2016-07-01

    Manganese homeostasis involves coordinated regulation of specific proteins involved in manganese influx and efflux. However, the proteins that are involved in detoxification/efflux have not been completely resolved nor has the basis by which they select their metal substrate. Here, we compared six proteins, which were reported to be involved in manganese detoxification/efflux, by evaluating their ability to reduce manganese toxicity in chicken DT40 cells, finding that human ZnT10 (hZnT10) was the most significant contributor. A domain swapping and substitution analysis between hZnT10 and the zinc-specific transporter hZnT1 showed that residue Asn(43), which corresponds to the His residue constituting the potential intramembranous zinc coordination site in other ZnT transporters, is necessary to impart hZnT10's unique manganese mobilization activity; residues Cys(52) and Leu(242) in transmembrane domains II and V play a subtler role in controlling the metal specificity of hZnT10. Interestingly, the His → Asn reversion mutant in hZnT1 conferred manganese transport activity and loss of zinc transport activity. These results provide important information about manganese detoxification/efflux mechanisms in vertebrate cells as well as the molecular characterization of hZnT10 as a manganese transporter. PMID:27226609

  12. SLC30A10: A novel manganese transporter.

    PubMed

    Chen, Pan; Bowman, Aaron B; Mukhopadhyay, Somshuvra; Aschner, Michael

    2015-01-01

    Homozygous mutations in SLC30A10 cause familial parkinsonism associated with manganese (Mn) retention. We recently identified SLC30A10 to be a cell surface-localized Mn efflux transporter and demonstrated that parkinsonism-causing mutations block its intracellular trafficking and efflux function. In C. elegans, SLC30A10 over-expression protected against Mn-induced lethality and dopaminergic neurotoxicity, consistent with results in mammalian systems. Here, we present new data about SLC30A10 function in C. elegans. SLC30A10 expression did not protect worms against ZnSO4toxicity, suggesting that SLC30A10 does not mediate Zn export in C. elegans. Furthermore, while a blast search identified 5 potential SLC30A10 homologs in worms (cdf-1, cdf-2, ttm-1 and toc-1; sequence identity <35%), knock-down of these genes showed a tendency of increased survival after Mn exposure (although only ttm-1 was statistically significant), suggesting that the worm homologs may function differently. PMID:26430566

  13. Spin-dependent electron transport in zinc- and manganese-doped adenine molecules

    SciTech Connect

    Simchi, Hamidreza; Esmaeilzadeh, Mahdi Mazidabadi, Hossein

    2014-01-28

    The spin-dependent electron transport properties of zinc- and manganese-doped adenine molecules connected to zigzag graphene leads are studied in the zero bias regime using the non-equilibrium Green's function method. The conductance of the adenine molecule increased and became spin-dependent when a zinc or manganese atom was doped into the molecules. The effects of a transverse electric field on the spin-polarization of the transmitted electrons were investigated and the spin-polarization was controlled by changing the transverse electric field. Under the presence of a transverse electric field, both the zinc- and manganese-doped adenine molecules acted as spin-filters. The maximum spin-polarization of the manganese-doped adenine molecule was greater than the molecule doped with zinc.

  14. Mn-euvering manganese: the role of transporter gene family members in manganese uptake and mobilization in plants

    PubMed Central

    Socha, Amanda L.; Guerinot, Mary Lou

    2014-01-01

    Manganese (Mn), an essential trace element, is important for plant health. In plants, Mn serves as a cofactor in essential processes such as photosynthesis, lipid biosynthesis and oxidative stress. Mn deficient plants exhibit decreased growth and yield and are more susceptible to pathogens and damage at freezing temperatures. Mn deficiency is most prominent on alkaline soils with approximately one third of the world's soils being too alkaline for optimal crop production. Despite the importance of Mn in plant development, relatively little is known about how it traffics between plant tissues and into and out of organelles. Several gene transporter families have been implicated in Mn transport in plants. These transporter families include NRAMP (natural resistance associated macrophage protein), YSL (yellow stripe-like), ZIP (zinc regulated transporter/iron-regulated transporter [ZRT/IRT1]-related protein), CAX (cation exchanger), CCX (calcium cation exchangers), CDF/MTP (cation diffusion facilitator/metal tolerance protein), P-type ATPases and VIT (vacuolar iron transporter). A combination of techniques including mutant analysis and Synchrotron X-ray Fluorescence Spectroscopy can assist in identifying essential transporters of Mn. Such knowledge would vastly improve our understanding of plant Mn homeostasis. PMID:24744764

  15. Mn-euvering manganese: the role of transporter gene family members in manganese uptake and mobilization in plants.

    PubMed

    Socha, Amanda L; Guerinot, Mary Lou

    2014-01-01

    Manganese (Mn), an essential trace element, is important for plant health. In plants, Mn serves as a cofactor in essential processes such as photosynthesis, lipid biosynthesis and oxidative stress. Mn deficient plants exhibit decreased growth and yield and are more susceptible to pathogens and damage at freezing temperatures. Mn deficiency is most prominent on alkaline soils with approximately one third of the world's soils being too alkaline for optimal crop production. Despite the importance of Mn in plant development, relatively little is known about how it traffics between plant tissues and into and out of organelles. Several gene transporter families have been implicated in Mn transport in plants. These transporter families include NRAMP (natural resistance associated macrophage protein), YSL (yellow stripe-like), ZIP (zinc regulated transporter/iron-regulated transporter [ZRT/IRT1]-related protein), CAX (cation exchanger), CCX (calcium cation exchangers), CDF/MTP (cation diffusion facilitator/metal tolerance protein), P-type ATPases and VIT (vacuolar iron transporter). A combination of techniques including mutant analysis and Synchrotron X-ray Fluorescence Spectroscopy can assist in identifying essential transporters of Mn. Such knowledge would vastly improve our understanding of plant Mn homeostasis. PMID:24744764

  16. High-affinity manganese uptake by the metal transporter NRAMP1 is essential for Arabidopsis growth in low manganese conditions.

    PubMed

    Cailliatte, Rémy; Schikora, Adam; Briat, Jean-François; Mari, Stéphane; Curie, Catherine

    2010-03-01

    In contrast with many other essential metals, the mechanisms of Mn acquisition in higher eukaryotes are seldom studied and poorly understood. We show here that Arabidopsis thaliana relies on a high-affinity uptake system to acquire Mn from the soil in conditions of low Mn availability and that this activity is catalyzed by the divalent metal transporter NRAMP1 (for Natural Resistance Associated Macrophage Protein 1). The nramp1-1 loss-of-function mutant grows poorly, contains less Mn than the wild type, and fails to take up Mn in conditions of Mn limitation, thus demonstrating that NRAMP1 is the major high-affinity Mn transporter in Arabidopsis. Based on confocal microscopy observation of an NRAMP1-green fluorescent protein fusion, we established that NRAMP1 is localized to the plasma membrane. Consistent with its function in Mn acquisition from the soil, NRAMP1 expression is restricted to the root and stimulated by Mn deficiency. Finally, we show that NRAMP1 restores the capacity of the iron-regulated transporter1 mutant to take up iron and cobalt, indicating that NRAMP1 has a broad selectivity in vivo. The role of transporters of the NRAMP family is well established in higher eukaryotes for iron but has been controversial for Mn. This study demonstrates that NRAMP1 is a physiological manganese transporter in Arabidopsis. PMID:20228245

  17. Redox processes controlling manganese fate and transport in a mountain stream.

    PubMed

    Scott, Durelle T; McKnight, Diane M; Voelker, Bettina M; Hrncir, Duane C

    2002-02-01

    The biogeochemical processes controlling the speciation and transport of manganese in a Colorado mountain stream were studied using a conservative tracer approach combined with laboratory experiments. The study stream, Lake Fork Creek, receives manganese-rich inflows from a wetland contaminated by acid mine drainage. A conservative tracer experiment was conducted on a 1300-m reach of the stream. Results indicate that manganese was progressively removed from the stream, resulting in a loss of 64 +/- 17 micromol day(-1) m(-1). Laboratory experiments using streamwater, mine effluent, and rocks from the stream showed the importance of surface-catalyzed oxidation and photoreduction on the speciation of manganese. The field and modeling results indicate that light generally promotes oxidation and removal of manganese from the stream, presumably through a photosynthetically enhanced oxidation process. Differences in Mn speciation within the stream suggest that reductive processes affect Mn speciation within the water column. These results identify the rapid oxidation and precipitation of MnOx as a dominant process within this freshwater stream. PMID:11871561

  18. CHROMIUM TRANSPORT, OXIDATION, AND ADSORPTION IN MANGANESE-COATED SAND

    EPA Science Inventory

    We examine how the processes of advection, dispersion, oxidation-reduction, and adsorption combine to affect the transport of chromium through columns packed with pyrolusite (P-MnO$-coated sand. We find that P-Mn02 effectively oxidizes Cr@I) to Cr(VI) and that the extent of oxida...

  19. Influence of film thickness and air exposure on the transport gap of manganese phthalocyanine

    SciTech Connect

    Haidu, F.; Fechner, A.; Salvan, G.; Gordan, O. D.; Fronk, M.; Zahn, D. R. T.; Lehmann, D.; Mahns, B.; Knupfer, M.

    2013-06-15

    The interface formation between manganese phthalocyanine (MnPc) and cobalt was investigated combining ultraviolet photoelectron spectroscopy and inverse photoelectron spectroscopy. The transport band gap of the MnPc increases with the film thickness up to a value of (1.2 {+-} 0.3) eV while the optical band gap as determined from spectroscopic ellipsometry amounts to 0.5 eV. The gap values are smaller compared to other phthalocyanines due to metallic Mn 3d states close to the Fermi level. The transport band gap was found to open upon air exposure as a result of the disappearance of the occupied 3d electronic states.

  20. Structural basis for the metal-selective activation of the manganese transport regulator of Bacillus subtilis.

    PubMed

    Kliegman, Joseph I; Griner, Sarah L; Helmann, John D; Brennan, Richard G; Glasfeld, Arthur

    2006-03-21

    The manganese transport regulator (MntR) of Bacillus subtilis is activated by Mn(2+) to repress transcription of genes encoding transporters involved in the uptake of manganese. MntR is also strongly activated by cadmium, both in vivo and in vitro, but it is poorly activated by other metal cations, including calcium and zinc. The previously published MntR.Mn(2+) structure revealed a binuclear complex of manganese ions with a metal-metal separation of 3.3 A (herein designated the AB conformer). Analysis of four additional crystal forms of MntR.Mn(2+) reveals that the AB conformer is only observed in monoclinic crystals at 100 K, suggesting that this conformation may be stabilized by crystal packing forces. In contrast, monoclinic crystals analyzed at room temperature (at either pH 6.5 or pH 8.5), and a second hexagonal crystal form (analyzed at 100 K), all reveal the shift of one manganese ion by 2.5 A, thereby leading to a newly identified conformation (the AC conformer) with an internuclear distance of 4.4 A. Significantly, the cadmium and calcium complexes of MntR also contain binuclear complexes with a 4.4 A internuclear separation. In contrast, the zinc complex of MntR contains only one metal ion per subunit, in the A site. Isothermal titration calorimetry confirms the stoichiometry of Mn(2+), Cd(2+), and Zn(2+) binding to MntR. We propose that the specificity of MntR activation is tied to productive binding of metal ions at two sites; the A site appears to act as a selectivity filter, determining whether the B or C site will be occupied and thereby fully activate MntR. PMID:16533030

  1. SLC39A8 Deficiency: A Disorder of Manganese Transport and Glycosylation.

    PubMed

    Park, Julien H; Hogrebe, Max; Grüneberg, Marianne; DuChesne, Ingrid; von der Heiden, Ava L; Reunert, Janine; Schlingmann, Karl P; Boycott, Kym M; Beaulieu, Chandree L; Mhanni, Aziz A; Innes, A Micheil; Hörtnagel, Konstanze; Biskup, Saskia; Gleixner, Eva M; Kurlemann, Gerhard; Fiedler, Barbara; Omran, Heymut; Rutsch, Frank; Wada, Yoshinao; Tsiakas, Konstantinos; Santer, René; Nebert, Daniel W; Rust, Stephan; Marquardt, Thorsten

    2015-12-01

    SLC39A8 is a membrane transporter responsible for manganese uptake into the cell. Via whole-exome sequencing, we studied a child that presented with cranial asymmetry, severe infantile spasms with hypsarrhythmia, and dysproportionate dwarfism. Analysis of transferrin glycosylation revealed severe dysglycosylation corresponding to a type II congenital disorder of glycosylation (CDG) and the blood manganese levels were below the detection limit. The variants c.112G>C (p.Gly38Arg) and c.1019T>A (p.Ile340Asn) were identified in SLC39A8. A second individual with the variants c.97G>A (p.Val33Met) and c.1004G>C (p.Ser335Thr) on the paternal allele and c.610G>T (p.Gly204Cys) on the maternal allele was identified among a group of unresolved case subjects with CDG. These data demonstrate that variants in SLC39A8 impair the function of manganese-dependent enzymes, most notably β-1,4-galactosyltransferase, a Golgi enzyme essential for biosynthesis of the carbohydrate part of glycoproteins. Impaired galactosylation leads to a severe disorder with deformed skull, severe seizures, short limbs, profound psychomotor retardation, and hearing loss. Oral galactose supplementation is a treatment option and results in complete normalization of glycosylation. SLC39A8 deficiency links a trace element deficiency with inherited glycosylation disorders. PMID:26637979

  2. SLC39A8 Deficiency: A Disorder of Manganese Transport and Glycosylation

    PubMed Central

    Park, Julien H.; Hogrebe, Max; Grüneberg, Marianne; DuChesne, Ingrid; von der Heiden, Ava L.; Reunert, Janine; Schlingmann, Karl P.; Boycott, Kym M.; Beaulieu, Chandree L.; Mhanni, Aziz A.; Innes, A. Micheil; Hörtnagel, Konstanze; Biskup, Saskia; Gleixner, Eva M.; Kurlemann, Gerhard; Fiedler, Barbara; Omran, Heymut; Rutsch, Frank; Wada, Yoshinao; Tsiakas, Konstantinos; Santer, René; Nebert, Daniel W.; Rust, Stephan; Marquardt, Thorsten

    2015-01-01

    SLC39A8 is a membrane transporter responsible for manganese uptake into the cell. Via whole-exome sequencing, we studied a child that presented with cranial asymmetry, severe infantile spasms with hypsarrhythmia, and dysproportionate dwarfism. Analysis of transferrin glycosylation revealed severe dysglycosylation corresponding to a type II congenital disorder of glycosylation (CDG) and the blood manganese levels were below the detection limit. The variants c.112G>C (p.Gly38Arg) and c.1019T>A (p.Ile340Asn) were identified in SLC39A8. A second individual with the variants c.97G>A (p.Val33Met) and c.1004G>C (p.Ser335Thr) on the paternal allele and c.610G>T (p.Gly204Cys) on the maternal allele was identified among a group of unresolved case subjects with CDG. These data demonstrate that variants in SLC39A8 impair the function of manganese-dependent enzymes, most notably β-1,4-galactosyltransferase, a Golgi enzyme essential for biosynthesis of the carbohydrate part of glycoproteins. Impaired galactosylation leads to a severe disorder with deformed skull, severe seizures, short limbs, profound psychomotor retardation, and hearing loss. Oral galactose supplementation is a treatment option and results in complete normalization of glycosylation. SLC39A8 deficiency links a trace element deficiency with inherited glycosylation disorders. PMID:26637979

  3. The Conformations of the Manganese Transport Regulator of Bacillus subtilis in its Metal-free State

    PubMed Central

    DeWitt, Mark A.; Kliegman, Joseph I.; Helmann, John D.; Brennan, Richard G.; Farrens, David L.; Glasfeld, Arthur

    2007-01-01

    The manganese transport regulator (MntR) from Bacillus subtilis binds cognate DNA sequences in response to elevated manganese concentrations. MntR functions as a homodimer that binds two manganese ions per subunit. Metal binding takes place at the interface of the two domains that comprise each MntR subunit: an N-terminal DNA-binding domain and a C-terminal dimerization domain. In order to elucidate the link between metal binding and activation, a crystallographic study of MntR in its metal-free state has been undertaken. Here we describe the structures of the native protein and a selenomethionine-containing variant, solved to 2.8 Å. The two structures contain five crystallographically unique subunits of MntR, providing diverse views of the metal-free protein. In apo-MntR, as in the manganese complex, the dimer is formed by dyad-related C-terminal domains that provide a conserved structural core. Similarly, each DNA-binding domain largely retains the folded conformation found in metal bound forms of MntR. However, compared to metal-activated MntR, the DNA-binding domains move substantially with respect to the dimer interface in apo-MntR. Overlays of multiple apo-MntR structures indicate that there is a greater range of positioning allowed between N and C-terminal domains in the metal-free state and that the DNA-binding domains of the dimer are farther apart than in the activated complex. To further investigate the conformation of the DNA-binding domain of apo-MntR, a site-directed spin labeling experiment was performed on a mutant of MntR containing cysteine at residue 6. Consistent with the crystallographic results, EPR spectra of the spin-labeled mutant indicate that tertiary structure is conserved in the presence or absence of bound metals, though slightly greater flexibility is present in inactive forms of MntR. PMID:17118401

  4. Borreliacidal activity of Borrelia metal transporter A (BmtA) binding small molecules by manganese transport inhibition.

    PubMed

    Wagh, Dhananjay; Pothineni, Venkata Raveendra; Inayathullah, Mohammed; Liu, Song; Kim, Kwang-Min; Rajadas, Jayakumar

    2015-01-01

    Borrelia burgdorferi, the causative agent of Lyme disease, utilizes manganese (Mn) for its various metabolic needs. We hypothesized that blocking Mn transporter could be a possible approach to inhibit metabolic activity of this pathogen and eliminate the infection. We used a combination of in silico protein structure prediction together with molecular docking to target the Borrelia metal transporter A (BmtA), a single known Mn transporter in Borrelia and screened libraries of FDA approved compounds that could potentially bind to the predicted BmtA structure with high affinity. Tricyclic antihistamines such as loratadine, desloratadine, and 3-hydroxydesloratadine as well as yohimbine and tadalafil demonstrated a tight binding to the in silico folded BmtA transporter. We, then, tested borreliacidal activity and dose response of the shortlisted compounds from this screen using a series of in vitro assays. Amongst the probed compounds, desloratadine exhibited potent borreliacidal activity in vitro at and above 78 μg/mL (250 μM). Borrelia treated with lethal doses of desloratadine exhibited a significant loss of intracellular Mn specifically and a severe structural damage to the bacterial cell wall. Our results support the possibility of developing a novel, targeted therapy to treat Lyme disease by targeting specific metabolic needs of Borrelia. PMID:25709405

  5. High-Affinity Manganese Uptake by the Metal Transporter NRAMP1 Is Essential for Arabidopsis Growth in Low Manganese Conditions[C][W

    PubMed Central

    Cailliatte, Rémy; Schikora, Adam; Briat, Jean-François; Mari, Stéphane; Curie, Catherine

    2010-01-01

    In contrast with many other essential metals, the mechanisms of Mn acquisition in higher eukaryotes are seldom studied and poorly understood. We show here that Arabidopsis thaliana relies on a high-affinity uptake system to acquire Mn from the soil in conditions of low Mn availability and that this activity is catalyzed by the divalent metal transporter NRAMP1 (for Natural Resistance Associated Macrophage Protein 1). The nramp1-1 loss-of-function mutant grows poorly, contains less Mn than the wild type, and fails to take up Mn in conditions of Mn limitation, thus demonstrating that NRAMP1 is the major high-affinity Mn transporter in Arabidopsis. Based on confocal microscopy observation of an NRAMP1-green fluorescent protein fusion, we established that NRAMP1 is localized to the plasma membrane. Consistent with its function in Mn acquisition from the soil, NRAMP1 expression is restricted to the root and stimulated by Mn deficiency. Finally, we show that NRAMP1 restores the capacity of the iron-regulated transporter1 mutant to take up iron and cobalt, indicating that NRAMP1 has a broad selectivity in vivo. The role of transporters of the NRAMP family is well established in higher eukaryotes for iron but has been controversial for Mn. This study demonstrates that NRAMP1 is a physiological manganese transporter in Arabidopsis. PMID:20228245

  6. Metal Binding Studies and EPR Spectroscopy of the Manganese Transport Regulator MntR†

    PubMed Central

    Golynskiy, Misha V.; Gunderson, William A.; Hendrich, Michael P.; Cohen, Seth M.

    2007-01-01

    Manganese transport regulator (MntR) is a member of the diphtheria toxin repressor (DtxR) family of transcription factors that is responsible for manganese homeostasis in Bacillus subtilis. Prior biophysical studies have focused on the metal-mediated DNA binding of MntR [Lieser, S. A., Davis, T. C., Helmann, J. D., and Cohen, S. M. (2003) Biochemistry 42, 12634-12642], as well as metal stabilization of the MntR structure [Golynskiy, M. V., Davis, T. C., Helmann, J. D., and Cohen, S. M. (2005) Biochemistry 44, 3380-3389], but only limited data on the metal-binding affinities for MntR are available. Herein, the metal-binding affinities of MntR were determined by using electron paramagnetic resonance (EPR) spectroscopy, as well as competition experiments with the fluorimetric dyes Fura-2 and Mag-fura-2. MntR was not capable of competing with Fura-2 for the binding of transition metal ions. Therefore, the metal-binding affinities and stoichiometries of Mag-fura-2 for Mn2+, Co2+, Ni2+, Zn2+, and Cd2+ were determined and utilized in MntR/Mag-fura-2 competition experiments. The measured Kd values for MntR metal binding are comparable to those reported for DtxR metal binding [Kd from 10-7 to 10-4 M; D’Aquino, J. A., et al. (2005) Proc. Natl. Acad. Sci. U.S.A. 102, 18408-18413], AntR [a homologue from Bacillus anthracis; Sen, K. I. et al. (2006) Biochemistry 45, 4295-4303], and generally follow the Irving-Williams series. Direct detection of the dinuclear Mn2+ site in MntR with EPR spectroscopy is presented, and the exchange interaction was determined, J = -0.2 cm-1. This value is lower in magnitude than most known dinuclear Mn2+ sites in proteins and synthetic complexes and is consistent with a dinuclear Mn2+ site with a longer Mn···Mn distance (4.4 Å) observed in some of the available crystal structures. MntR is found to have a surprisingly low binding affinity (∼160 μM) for its cognate metal ion Mn2+. Moreover, the results of DNA binding studies in the presence

  7. The Structural Basis for the Metal Selective Activation of the Manganese Transport Regulator of Bacillus subtilis†,§

    PubMed Central

    Kliegman, Joseph I.; Griner, Sarah L.; Helmann, John D.; Brennan, Richard G.; Glasfeld, Arthur

    2008-01-01

    The manganese transport regulator (MntR) of Bacillus subtilis is activated by Mn2+ to repress transcription of genes encoding transporters involved in the uptake of manganese. MntR is also strongly activated by cadmium, both in vivo and in vitro, but it is poorly activated by other metal cations, including calcium and zinc. The previously published MntR•Mn2+ structure revealed a binuclear complex of manganese ions with a metal-metal separation of 3.3 Å (herein designated the AB conformer). Analysis of four additional crystal forms of MntR•Mn2+ reveals that the AB conformer is only observed in monoclinic crystals at 100 K, suggesting that this conformation may be stabilized by crystal packing forces. In contrast, monoclinic crystals analyzed at room temperature (at either pH 6.5 or 8.5), and a second hexagonal crystal form (analyzed at 100 K), all reveal the shift of one manganese ion by 2.5 Å thereby leading to a newly identified conformation (the AC conformer) with an internuclear distance of 4.4 Å. Significantly, the cadmium and calcium complexes of MntR also contain binuclear complexes with a 4.4 Å internuclear separation. In contrast, the zinc complex of MntR contains only one metal ion per subunit, in the A site. Isothermal titration calorimetry confirms the stoichiometry of Mn2+, Cd2+ and Zn2+ binding to MntR. We propose that the specificity of MntR activation is tied to productive binding of metal ions at two sites; the A site appears to act as a selectivity filter, determining whether the B or C site will be occupied and thereby fully activate MntR. PMID:16533030

  8. The Vacuolar Manganese Transporter MTP8 Determines Tolerance to Iron Deficiency-Induced Chlorosis in Arabidopsis.

    PubMed

    Eroglu, Seckin; Meier, Bastian; von Wirén, Nicolaus; Peiter, Edgar

    2016-02-01

    Iron (Fe) deficiency is a widespread nutritional disorder on calcareous soils. To identify genes involved in the Fe deficiency response, Arabidopsis (Arabidopsis thaliana) transfer DNA insertion lines were screened on a high-pH medium with low Fe availability. This approach identified METAL TOLERANCE PROTEIN8 (MTP8), a member of the Cation Diffusion Facilitator family, as a critical determinant for the tolerance to Fe deficiency-induced chlorosis, also on soil substrate. Subcellular localization to the tonoplast, complementation of a manganese (Mn)-sensitive Saccharomyces cerevisiae yeast strain, and Mn sensitivity of mtp8 knockout mutants characterized the protein as a vacuolar Mn transporter suitable to prevent plant cells from Mn toxicity. MTP8 expression was strongly induced on low-Fe as well as high-Mn medium, which were both strictly dependent on the transcription factor FIT, indicating that high-Mn stress induces Fe deficiency. mtp8 mutants were only hypersensitive to Fe deficiency when Mn was present in the medium, which further suggested an Mn-specific role of MTP8 during Fe limitation. Under those conditions, mtp8 mutants not only translocated more Mn to the shoot than did wild-type plants but suffered in particular from critically low Fe concentrations and, hence, Fe chlorosis, although the transcriptional Fe deficiency response was up-regulated more strongly in mtp8. The diminished uptake of Fe from Mn-containing low-Fe medium by mtp8 mutants was caused by an impaired ability to boost the ferric chelate reductase activity, which is an essential process in Fe acquisition. These findings provide a mechanistic explanation for the long-known interference of Mn in Fe nutrition and define the molecular processes by which plants alleviate this antagonism. PMID:26668333

  9. Infectious Prion Protein Alters Manganese Transport and Neurotoxicity in a Cell Culture Model of Prion Disease

    PubMed Central

    Martin, Dustin P.; Anantharam, Vellareddy; Jin, Huajun; Witte, Travis; Houk, Robert; Kanthasamy, Arthi; Kanthasamy, Anumantha G.

    2011-01-01

    Protein misfolding and aggregation are considered key features of many neurodegenerative diseases, but biochemical mechanisms underlying protein misfolding and the propagation of protein aggregates are not well understood. Prion disease is a classical neurodegenerative disorder resulting from the misfolding of endogenously expressed normal cellular prion protein (PrPC). Although the exact function of PrPC has not been fully elucidated, studies have suggested that it can function as a metal binding protein. Interestingly, increased brain manganese (Mn) levels have been reported in various prion diseases indicating divalent metals also may play a role in the disease process. Recently, we reported that PrPC protects against Mn-induced cytotoxicity in a neural cell culture model. To further understand the role of Mn in prion diseases, we examined Mn neurotoxicity in an infectious cell culture model of prion disease. Our results show CAD5 scrapie-infected cells were more resistant to Mn neurotoxicity as compared to uninfected cells (EC50 = 428.8 μM for CAD5 infected cells vs. 211.6 μM for uninfected cells). Additionally, treatment with 300 μM Mn in persistently infected CAD5 cells showed a reduction in mitochondrial impairment, caspase-3 activation, and DNA fragmentation when compared to uninfected cells. Scrapie-infected cells also showed significantly reduced Mn uptake as measured by inductively coupled plasma-mass spectrometry (ICP-MS), and altered expression of metal transporting proteins DMT1 and transferrin. Together, our data indicate that conversion of PrP to the pathogenic isoform enhances its ability to regulate Mn homeostasis, and suggest that understanding the interaction of metals with disease-specific proteins may provide further insight to protein aggregation in neurodegenerative diseases. PMID:21871919

  10. Structural Elements in the Transmembrane and Cytoplasmic Domains of the Metal Transporter SLC30A10 Are Required for Its Manganese Efflux Activity.

    PubMed

    Zogzas, Charles E; Aschner, Michael; Mukhopadhyay, Somshuvra

    2016-07-29

    Homozygous mutations in SLC30A10 lead to the development of familial manganese-induced parkinsonism. We previously demonstrated that SLC30A10 is a cell surface-localized manganese efflux transporter, and parkinsonism-causing mutations block its trafficking and efflux activity. Interestingly, other transporters in the SLC30 family mediate zinc efflux. Determining the mechanisms that allow SLC30A10 to transport manganese, which are unclear, is essential to understand its role in parkinsonism. Here, we generated a predicted structure of SLC30A10, based on the structure of the bacterial zinc transporter YiiP, and performed functional studies. In YiiP, side chains of residues Asp-45 and Asp-49 in the second and His-153 and Asp-157 in the fifth transmembrane segments coordinate zinc and are required for transport. In SLC30A10, the corresponding residues are Asn-43 and Asp-47 in the second and His-244 and Asp-248 in the fifth transmembrane segments. Surprisingly, although alanine substitution of Asp-248 abolished manganese efflux, that of Asn-43 and Asp-47 did not. Instead, side chains of charged or polar residues adjacent to Asp-248 in the first (Glu-25) or fourth (Asn-127) transmembrane segments were required. Further analyses revealed that residues His-333 and His-350 in the cytoplasmic C-terminal domain were required for full activity. However, the C-terminal domain failed to transfer manganese transport capability to a related zinc transporter. Overall, our results indicate that residues in the transmembrane and C-terminal domains together confer optimal manganese transport capability to SLC30A10 and suggest that the mechanism of ion coordination in the transmembrane domain of SLC30A10 may be substantially different from that in YiiP/other SLC30 proteins. PMID:27307044

  11. Intracellular localization and subsequent redistribution of metal transporters in a rat choroid plexus model following exposure to manganese or iron

    SciTech Connect

    Wang Xueqian; Miller, David S.

    2008-07-15

    Confocal microscopy was used to investigate the effects of manganese (Mn) and iron (Fe) exposure on the subcellular distribution of metal transporting proteins, i.e., divalent metal transporter 1 (DMT1), metal transporter protein 1 (MTP1), and transferrin receptor (TfR), in the rat intact choroid plexus which comprises the blood-cerebrospinal fluid barrier. In control tissue, DMT1 was concentrated below the apical epithelial membrane, MTP1 was diffuse within the cytosol, and TfR was distributed in vesicles around nuclei. Following Mn or Fe treatment (1 and 10 {mu}M), the distribution of DMT1 was not affected. However, MTP1 and TfR moved markedly toward the apical pole of the cells. These shifts were abolished when microtubules were disrupted. Quantitative RT-PCR and Western blot analyses revealed a significant increase in mRNA and protein levels of TfR but not DMT1 and MTP1 after Mn exposure. These results suggest that early events in the tissue response to Mn or Fe exposure involve microtubule-dependent, intracellular trafficking of MTP1 and TfR. The intracellular trafficking of metal transporters in the choroid plexus following Mn exposure may partially contribute to Mn-induced disruption in Fe homeostasis in the cerebrospinal fluid (CSF) following Mn exposure.

  12. Intracellular Localization and Subsequent Redistribution of Metal Transporters in a Rat Choroid Plexus Model Following Exposure to Manganese or Iron

    PubMed Central

    Wang, Xueqian; Miller, David S.; Zheng, Wei

    2008-01-01

    Confocal microscopy was used to investigate the effects of manganese (Mn) and iron (Fe) exposure on the subcellular distribution of metal transporting proteins, i.e., divalent metal transporter 1 (DMT1), metal transporter protein 1 (MTP1), and transferrin receptor (TfR), in the rat intact choroid plexus which comprises the blood-cerebrospinal fluid barrier. In control tissue, DMT1 was concentrated below the apical epithelial membrane, MTP1 was diffuse within the cytosol, and TfR was distributed in vesicles around nuclei. Following Mn or Fe treatment (1 and 10 µM), the distribution of DMT1 was not affected. However, MTP1 and TfR moved markedly toward the apical pole of the cells. These shifts were abolished when microtubules were disrupted. Quantitative RT-PCR and Western blot analyses revealed a significant increase in mRNA and protein levels of TfR but not DMT1 and MTP1 after Mn exposure. These results suggest that early events in the tissue response to Mn or Fe exposure involve microtubule-dependent, intracellular trafficking of MTP1 and TfR. The intracellular trafficking of metal transporters in the choroid plexus following Mn exposure may partially contribute to Mn-induced disruption in Fe homeostasis in the cerebrospinal fluid (CSF) following Mn exposure. PMID:18420243

  13. The manganese-responsive regulator MntR represses transcription of a predicted ZIP family metal ion transporter in Corynebacterium glutamicum.

    PubMed

    Baumgart, Meike; Frunzke, Julia

    2015-01-01

    Manganese is an important trace element required as an enzyme cofactor and for protection against oxidative stress. In this study, we characterized the DtxR-type transcriptional regulator MntR (cg0741) of Corynebacterium glutamicum ATCC 13032 as a manganese-dependent repressor of the predicted ZIP family metal transporter Cg1623. Comparative transcriptome analysis of a ΔmntR strain and the wild type led to the identification of cg1623 as potential target gene of MntR which was about 50-fold upregulated when cells were grown in glucose minimal medium. Using electrophoretic mobility shift assays, a conserved 18 bp inverted repeat (TGTTCAATGCGTTGAACA) was identified as binding motif of MntR in the cg1623 promoter and confirmed by mutational analysis. Promoter fusion of Pcg1623 to eyfp confirmed that the MntR-dependent repression is only abolished in the absence of manganese. However, neither deletion of mntR nor cg1623 resulted in a significant growth phenotype in comparison to the wild type--strongly suggesting the presence of further manganese uptake and efflux systems in C. glutamicum. The control of cg1623 by the DtxR-type regulator MntR represents the first example of a predicted ZIP family protein that is regulated in a manganese-dependent manner in bacteria. PMID:25790484

  14. Immunisation With Immunodominant Linear B Cell Epitopes Vaccine of Manganese Transport Protein C Confers Protection against Staphylococcus aureus Infection.

    PubMed

    Yang, Hui-Jie; Zhang, Jin-Yong; Wei, Chao; Yang, Liu-Yang; Zuo, Qian-Fei; Zhuang, Yuan; Feng, You-Jun; Srinivas, Swaminath; Zeng, Hao; Zou, Quan-Ming

    2016-01-01

    Vaccination strategies for Staphylococcus aureus, particularly methicillin-resistant S. aureus (MRSA) infections have attracted much research attention. Recent efforts have been made to select manganese transport protein C, or manganese binding surface lipoprotein C (MntC), which is a metal ion associated with pathogen nutrition uptake, as potential candidates for an S. aureus vaccine. Although protective humoral immune responses to MntC are well-characterised, much less is known about detailed MntC-specific B cell epitope mapping and particularly epitope vaccines, which are less-time consuming and more convenient. In this study, we generated a recombinant protein rMntC which induced strong antibody response when used for immunisation with CFA/IFA adjuvant. On the basis of the results, linear B cell epitopes within MntC were finely mapped using a series of overlapping synthetic peptides. Further studies indicate that MntC113-136, MntC209-232, and MntC263-286 might be the original linear B-cell immune dominant epitope of MntC, furthermore, three-dimensional (3-d) crystal structure results indicate that the three immunodominant epitopes were displayed on the surface of the MntC antigen. On the basis of immunodominant MntC113-136, MntC209-232, and MntC263-286 peptides, the epitope vaccine for S. aureus induces a high antibody level which is biased to TH2 and provides effective immune protection and strong opsonophagocytic killing activity in vitro against MRSA infection. In summary, the study provides strong proof of the optimisation of MRSA B cell epitope vaccine designs and their use, which was based on the MntC antigen in the development of an MRSA vaccine. PMID:26895191

  15. Staphylococcus aureus Manganese Transport Protein C (MntC) Is an Extracellular Matrix- and Plasminogen-Binding Protein

    PubMed Central

    Salazar, Natália; Castiblanco-Valencia, Mónica Marcela; da Silva, Ludmila Bezerra; de Castro, Íris Arantes; Monaris, Denize; Masuda, Hana Paula; Barbosa, Angela Silva; Arêas, Ana Paula Mattos

    2014-01-01

    Infections caused by Staphylococcus aureus – particularly nosocomial infections - represent a great concern. Usually, the early stage of pathogenesis consists on asymptomatic nasopharynx colonization, which could result in dissemination to other mucosal niches or invasion of sterile sites, such as blood. This pathogenic route depends on scavenging of nutrients as well as binding to and disrupting extracellular matrix (ECM). Manganese transport protein C (MntC), a conserved manganese-binding protein, takes part in this infectious scenario as an ion-scavenging factor and surprisingly as an ECM and coagulation cascade binding protein, as revealed in this work. This study showed a marked ability of MntC to bind to several ECM and coagulation cascade components, including laminin, collagen type IV, cellular and plasma fibronectin, plasminogen and fibrinogen by ELISA. The MntC binding to plasminogen appears to be related to the presence of surface-exposed lysines, since previous incubation with an analogue of lysine residue, ε-aminocaproic acid, or increasing ionic strength affected the interaction between MntC and plasminogen. MntC-bound plasminogen was converted to active plasmin in the presence of urokinase plasminogen activator (uPA). The newly released plasmin, in turn, acted in the cleavage of the α and β chains of fibrinogen. In conclusion, we describe a novel function for MntC that may help staphylococcal mucosal colonization and establishment of invasive disease, through the interaction with ECM and coagulation cascade host proteins. These data suggest that this potential virulence factor could be an adequate candidate to compose an anti-staphylococcal human vaccine formulation. PMID:25409527

  16. Immunisation With Immunodominant Linear B Cell Epitopes Vaccine of Manganese Transport Protein C Confers Protection against Staphylococcus aureus Infection

    PubMed Central

    Yang, Hui-Jie; Zhang, Jin-Yong; Wei, Chao; Yang, Liu-Yang; Zuo, Qian-Fei; Zhuang, Yuan; Feng, You-Jun; Srinivas, Swaminath; Zeng, Hao; Zou, Quan-Ming

    2016-01-01

    Vaccination strategies for Staphylococcus aureus, particularly methicillin-resistant S. aureus (MRSA) infections have attracted much research attention. Recent efforts have been made to select manganese transport protein C, or manganese binding surface lipoprotein C (MntC), which is a metal ion associated with pathogen nutrition uptake, as potential candidates for an S. aureus vaccine. Although protective humoral immune responses to MntC are well-characterised, much less is known about detailed MntC-specific B cell epitope mapping and particularly epitope vaccines, which are less-time consuming and more convenient. In this study, we generated a recombinant protein rMntC which induced strong antibody response when used for immunisation with CFA/IFA adjuvant. On the basis of the results, linear B cell epitopes within MntC were finely mapped using a series of overlapping synthetic peptides. Further studies indicate that MntC113-136, MntC209-232, and MntC263-286 might be the original linear B-cell immune dominant epitope of MntC, furthermore, three-dimensional (3-d) crystal structure results indicate that the three immunodominant epitopes were displayed on the surface of the MntC antigen. On the basis of immunodominant MntC113-136, MntC209-232, and MntC263-286 peptides, the epitope vaccine for S. aureus induces a high antibody level which is biased to TH2 and provides effective immune protection and strong opsonophagocytic killing activity in vitro against MRSA infection. In summary, the study provides strong proof of the optimisation of MRSA B cell epitope vaccine designs and their use, which was based on the MntC antigen in the development of an MRSA vaccine. PMID:26895191

  17. The Staphylococcus aureus ABC-Type Manganese Transporter MntABC Is Critical for Reinitiation of Bacterial Replication Following Exposure to Phagocytic Oxidative Burst

    PubMed Central

    Coady, Alison; Xu, Min; Phung, Qui; Cheung, Tommy K.; Bakalarski, Corey; Alexander, Mary Kate; Lehar, Sophie M.; Kim, Janice; Park, Summer; Tan, Man-Wah; Nishiyama, Mireille

    2015-01-01

    Manganese plays a central role in cellular detoxification of reactive oxygen species (ROS). Therefore, manganese acquisition is considered to be important for bacterial pathogenesis by counteracting the oxidative burst of phagocytic cells during host infection. However, detailed analysis of the interplay between bacterial manganese acquisition and phagocytic cells and its impact on bacterial pathogenesis has remained elusive for Staphylococcus aureus, a major human pathogen. Here, we show that a mntC mutant, which lacks the functional manganese transporter MntABC, was more sensitive to killing by human neutrophils but not murine macrophages, unless the mntC mutant was pre-exposed to oxidative stress. Notably, the mntC mutant formed strikingly small colonies when recovered from both type of phagocytic cells. We show that this phenotype is a direct consequence of the inability of the mntC mutant to reinitiate growth after exposure to phagocytic oxidative burst. Transcript and quantitative proteomics analyses revealed that the manganese-dependent ribonucleotide reductase complex NrdEF, which is essential for DNA synthesis and repair, was highly induced in the mntC mutant under oxidative stress conditions including after phagocytosis. Since NrdEF proteins are essential for S. aureus viability we hypothesize that cells lacking MntABC might attempt to compensate for the impaired function of NrdEF by increasing their expression. Our data suggest that besides ROS detoxification, functional manganese acquisition is likely crucial for S. aureus pathogenesis by repairing oxidative damages, thereby ensuring efficient bacterial growth after phagocytic oxidative burst, which is an attribute critical for disseminating and establishing infection in the host. PMID:26379037

  18. Manganese Efficiency in Barley: Identification and Characterization of the Metal Ion Transporter HvIRT11[OA

    PubMed Central

    Pedas, Pai; Ytting, Cecilie K.; Fuglsang, Anja T.; Jahn, Thomas P.; Schjoerring, Jan K.; Husted, Søren

    2008-01-01

    Manganese (Mn) deficiency is an important plant nutritional disorder in many parts of the world. Barley (Hordeum vulgare) genotypes differ considerably in their ability to grow in soils with low Mn2+ availability. Differential genotypic Mn efficiency can be attributed to differences in Mn2+ uptake kinetics in the low nanomolar concentration range. However, the molecular basis for these differences has not yet been clarified. We present here the identification and characterization of the first barley gene encoding a plasma membrane-localized metal transport protein able to transport Mn2+. The gene is designated HvIRT1 (for IRON-REGULATED TRANSPORTER1) because it belongs to the ZIP gene family and has a high similarity to rice (Oryza sativa) OsIRT1. A novel yeast uptake assay based on inductively coupled plasma-mass spectrometry analysis of 31 different metal and metalloid ions showed that the HvIRT1 protein, in addition to Mn2+, also transported Fe2+/Fe3+, Zn2+, and Cd2+. Both Mn and iron deficiency induced an up-regulation of HvIRT1 in two barley genotypes differing in Mn efficiency, but the expression levels in all cases were highest (up to 40%) in the Mn-efficient genotype. The higher expression of HvIRT1 correlated with an increased Mn2+ uptake rate. We conclude that HvIRT1 is an important component controlling Mn2+ uptake in barley roots and contributes to genotypic differences in Mn2+ uptake kinetics. PMID:18614714

  19. Manganese transporters Yfe and MntH are Fur-regulated and important for the virulence of Yersinia pestis

    PubMed Central

    Craig, Susannah K.; Abney, Jennifer; Bobrov, Alexander G.; Kirillina, Olga; Mier, Ildefonso; Truszczynska, Helena; Fetherston, Jacqueline D.

    2012-01-01

    Yersinia pestis has a flea-mammal-flea transmission cycle, and is a zoonotic pathogen that causes the systemic diseases bubonic and septicaemic plague in rodents and humans, as well as pneumonic plague in humans and non-human primates. Bubonic and pneumonic plague are quite different diseases that result from different routes of infection. Manganese (Mn) acquisition is critical for the growth and pathogenesis of a number of bacteria. The Yfe/Sit and/or MntH systems are the two prominent Mn transporters in Gram-negative bacteria. Previously we showed that the Y. pestis Yfe system transports Fe and Mn. Here we demonstrate that a mutation in yfe or mntH did not significantly affect in vitro aerobic growth under Mn-deficient conditions. A yfe mntH double mutant did exhibit a moderate growth defect which was alleviated by supplementation with Mn. No short-term energy-dependent uptake of 54Mn was observed in this double mutant. Like the yfeA promoter, the mntH promoter was repressed by both Mn and Fe via Fur. Sequences upstream of the Fur binding sequence in the yfeA promoter converted an iron-repressible promoter to one that is also repressed by Mn and Fe. To our knowledge, this is the first report identifying cis promoter elements needed to alter cation specificities involved in transcriptional repression. Finally, the Y. pestis yfe mntH double mutant had an ~133-fold loss of virulence in a mouse model of bubonic plague but no virulence loss in the pneumonic plague model. This suggests that Mn availability, bacterial Mn requirements or Mn transporters used by Y. pestis are different in the lungs (pneumonic plague) compared with systemic disease. PMID:22222497

  20. The importance of glutamate, glycine, and {gamma}-aminobutyric acid transport and regulation in manganese, mercury and lead neurotoxicity

    SciTech Connect

    Fitsanakis, Vanessa A.; Aschner, Michael . E-mail: michael.aschner@vanderbilt.edu

    2005-05-01

    Historically, amino acids were studied in the context of their importance in protein synthesis. In the 1950s, the focus of research shifted as amino acids were recognized as putative neurotransmitters. Today, many amino acids are considered important neurochemicals. Although many amino acids play a role in neurotransmission, glutamate (Glu), glycine (Gly), and {gamma}-aminobutyric acid (GABA) are among the more prevalent and better understood. Glu, the major excitatory neurotransmitter, and Gly and GABA, the major inhibitory neurotransmitters, in the central nervous system, are known to be tightly regulated. Prolonged exposure to environmental toxicants, such as manganese (Mn), mercury (Hg), or lead (Pb), however, can lead to dysregulation of these neurochemicals and subsequent neurotoxicity. While the ability of these metals to disrupt the regulation of Glu, Gly and GABA have been studied, few articles have examined the collective role of these amino acids in the respective metal's mechanism of toxicity. For each of the neurotransmitters above, we will provide a brief synopsis of their regulatory function, including the importance of transport and re-uptake in maintaining their optimal function. Additionally, the review will address the hypothesis that aberrant homeostasis of any of these amino acids, or a combination of the three, plays a role in the neurotoxicity of Mn, Hg, or Pb.

  1. Electrical transport properties of manganese containing pyrochlore type semiconducting oxides using impedance analyses

    SciTech Connect

    Sumi, S.; Prabhakar Rao, P.; Mahesh, S.K.; Koshy, Peter

    2012-12-15

    Graphical abstract: DC conductivity variation of CaCe{sub 1−x}Mn{sub x}SnNbO{sub 7−δ} (x = 0, 0.2, 0.4 and 0.6) with inverse of temperature. Variation of conductivity with Mn concentration at 600 °C is shown in the inset. Display Omitted Highlights: ► We have observed that the structural ordering as well as grain size increase with Mn substitution. ► Impedance analysis proved that a correlated barrier hopping type conduction mechanism is involved in the materials. ► Activation energy as well as electrical conductivity increases with increase in Mn substitution. ► Localization of electrons associated with Mn{sup 2+} and structural ordering are the key factors for the increased activation energy with Mn substitution. ► All the materials showed good NTC thermistor properties. -- Abstract: A new series of manganese containing pyrochlore type semiconducting oxides CaCe{sub 1−x}Mn{sub x}SnNbO{sub 7−δ} (x = 0, 0.2, 0.4 and 0.6) have been synthesized to study the effect of Mn substitution on the structure, microstructure and electrical properties of these samples. X-ray diffraction and scanning electron microscopy studies revealed an increase of structural ordering and grain size respectively with increase of Mn substitution. Rietveld analysis and Raman spectroscopy were also employed to corroborate the XRD results. The bulk resistance measurements with temperature exhibit negative temperature coefficient behavior. The impedance analysis of the samples revealed a non-Debye type relaxation existed in the materials. The ac conductivity variation with temperature and frequency indicates a correlated barrier hopping type conduction mechanism in these materials. The barrier height and the intersite separation for hopping influence the electrical conductivity of these samples and are found to be a function of localization of electrons associated with the Mn{sup 2+} ions and the unit cell volume respectively. The Mn substitution increases both electrical

  2. Development of a transportable neutron activation analysis system to quantify manganese in bone in vivo: feasibility and methodology

    PubMed Central

    Liu, Yingzi; Koltick, David; Byrne, Patrick; Wang, Haoyu; Zheng, Wei; Nie, Linda H

    2014-01-01

    This study was conducted to investigate the methodology and feasibility of developing a transportable neutron activation analysis (NAA) system to quantify manganese (Mn) in bone using a portable deuterium–deuterium (DD) neutron generator as the neutron source. Since a DD neutron generator was not available in our laboratory, a deuterium–tritium (DT) neutron generator was used to obtain experimental data and validate the results from Monte Carlo (MC) simulations. After validation, MC simulations using a DD generator as the neutron source were then conducted. Different types of moderators and reflectors were simulated, and the optimal thicknesses for the moderator and reflector were determined. To estimate the detection limit (DL) of the system, and to observe the interference of the magnesium (Mg) γ line at 844 keV to the Mn γ line at 847 keV, three hand phantoms with Mn concentrations of 30 parts per million (ppm), 150 ppm, and 500 ppm were made and irradiated by the DT generator system. The Mn signals in these phantoms were then measured using a 50% high-efficiency high-purity germanium (HPGe) detector. The DL was calculated to be about 4.4 ppm for the chosen irradiation, decay, and measurement time. This was calculated to be equivalent to a DL of about 3.3 ppm for the DD generator system. To achieve this DL with one 50% high-efficiency HPGe detector, the dose to the hand was simulated to be about 37 mSv, with the total body equivalent dose being about 23μSv. In conclusion, it is feasible to develop a transportable NAA system to quantify Mn in bone in vivo with an acceptable radiation exposure to the subject. PMID:24165395

  3. Iron and manganese speciation and cycling in glacially influenced high-latitude fjord sediments (West Spitsbergen, Svalbard): Evidence for a benthic recycling-transport mechanism

    NASA Astrophysics Data System (ADS)

    Wehrmann, Laura M.; Formolo, Michael J.; Owens, Jeremy D.; Raiswell, Robert; Ferdelman, Timothy G.; Riedinger, Natascha; Lyons, Timothy W.

    2014-09-01

    Glacial environments may provide an important but poorly constrained source of potentially bioavailable iron and manganese phases to the coastal ocean in high-latitude regions. Little is known about the fate and biogeochemical cycling of glacially derived iron and manganese in the coastal marine realm. Sediment and porewater samples were collected along transects from the fjord mouths to the tidewater glaciers at the fjord heads in Smeerenburgfjorden, Kongsfjorden, and Van Keulenfjorden along Western Svalbard. Solid-phase iron and manganese speciation, determined by sequential chemical extraction, could be linked to the compositions of the local bedrock and hydrological/weathering conditions below the local glaciers. The concentration and sulfur isotope composition of chromium reducible sulfur (CRS) in Kongs- and Van Keulenfjorden sediments largely reflect the delivery rate and isotope composition of detrital pyrite originating from adjacent glaciers. The varying input of reducible iron and manganese oxide phases and the input of organic matter of varying reactivity control the pathways of organic carbon mineralization in the sediments of the three fjords. High reducible iron and manganese oxide concentrations and elevated metal accumulation rates coupled to low input of “fresh” organic matter lead to a strong expression of dissimilatory metal oxide reduction evidenced in very high porewater iron (up to 800 μM) and manganese (up to 210 μM) concentrations in Kongsfjorden and Van Keulenfjorden. Sediment reworking by the benthic macrofauna and physical sediment resuspension via iceberg calving may be additional factors that promote extensive benthic iron and manganese cycling in these fjords. On-going benthic recycling of glacially derived dissolved iron into overlying seawater, where partial re-oxidation and deposition occurs, facilitates the transport of iron across the fjords and potentially into adjacent continental shelf waters. Such iron-dominated fjord

  4. Structure, Electrical Transport and Magneto-Resistance Properties of La5/8Ca3/8MnO3 Manganite Synthesized with Different Manganese Precursors

    NASA Astrophysics Data System (ADS)

    Navasery, M.; Halim, S. A.; Lim, K. P.; Chen, S. K.; Roslan, A. S.; Abd-Shukor, R.

    We synthesized the polycrystalline manganite of La5/8Ca3/8MnO3 with three different manganese routes prepared through a solid state reaction method. The effects of the manganese route selection on the structure, electrical transport and magneto-transport properties were examined in this study. The samples were characterized using X-ray diffraction (XRD) and SEM to identify their structure and morphology. XRD analysis confirmed that all samples were in single phase with orthorhombic structure and belonged to the Pnma space group. The average grain sized samples with manganese route of Mn2O3 and MnCO3 had a grain size of 1.2-8.7 μm and 2-7.5 μm, respectively. For the MnO2 route, the sample had a small melt-like shape with higher porosity. The metal-insulator transition temperature, TMI, for LCMO (Mn2O3), LCMO (MnO2) and LCMO (MnCO3) samples were 270 K, 266 K and 258 K, respectively. All the samples showed negative magneto-resistance with significant increase in value near the TMI temperature. The highest CMR (colossal magneto-resistance) ratio was found in LCMO (Mn2O3), -22.06% at 270 K, followed by -16.69% for LCMO (MnO2) at 80 K, and 15.2% for LCMO (MnCO3) at 100 K in a 1 T magnetic field.

  5. Manganese and its Role in Parkinson’s Disease: From Transport to Neuropathology

    PubMed Central

    Erikson, Keith M.; Hernández, Elena Herrero; Tjalkens, Ronald

    2015-01-01

    The purpose of this review is to highlight recent advances in the neuropathology associated with Mn exposures. We commence with a discussion on occupational manganism and clinical aspects of the disorder. This is followed by novel considerations on Mn transport (see also chapter by Yokel, this volume), advancing new hypotheses on the involvement of several transporters in Mn entry into the brain. This is followed by a brief description of the effects of Mn on neurotransmitter systems that are putative modulators of dopamine (DA) biology (the primary target of Mn neurotoxicity), as well as its effects on mitochondrial dysfunction and disruption of cellular energy metabolism. Next, we discuss inflammatory activation of glia in neuronal injury and how disruption of synaptic transmission and glial-neuronal communication may serve as underlying mechanisms of Mn-induced neurodegeneration commensurate with the cross-talk between glia and neurons. We conclude with a discussion on therapeutic aspects of Mn exposure. Emphasis is directed at treatment modalities and the utility of chelators in attenuating the neurodegenerative sequelae of exposure to Mn. For additional reading on several topics inherent to this review as well as others, the reader may wish to consult Aschner and Dorman (Toxicological Review 25:147–154, 2007) and Bowman et al. (Metals and neurodegeneration, 2009). PMID:19657747

  6. Postnatal manganese exposure alters dopamine transporter function in adult rats: Potential impact on nonassociative and associative processes.

    PubMed

    McDougall, S A; Reichel, C M; Farley, C M; Flesher, M M; Der-Ghazarian, T; Cortez, A M; Wacan, J J; Martinez, C E; Varela, F A; Butt, A E; Crawford, C A

    2008-06-23

    In the present study, we examined whether exposing rats to a high-dose regimen of manganese chloride (Mn) during the postnatal period would depress presynaptic dopamine functioning and alter nonassociative and associative behaviors. To this end, rats were given oral supplements of Mn (750 microg/day) on postnatal days (PD) 1-21. On PD 90, dopamine transporter (DAT) immunoreactivity and [3H]dopamine uptake were assayed in the striatum and nucleus accumbens, while in vivo microdialysis was used to measure dopamine efflux in the same brain regions. The effects of postnatal Mn exposure on nigrostriatal functioning were evaluated by assessing rotorod performance and amphetamine-induced stereotypy in adulthood. In terms of associative processes, both cocaine-induced conditioned place preference (CPP) and sucrose-reinforced operant responding were examined. Results showed that postnatal Mn exposure caused persistent declines in DAT protein expression and [3H]dopamine uptake in the striatum and nucleus accumbens, as well as long-term reductions in striatal dopamine efflux. Rotorod performance did not differ according to exposure condition, however Mn-exposed rats did exhibit substantially more amphetamine-induced stereotypy than vehicle controls. Mn exposure did not alter performance on any aspect of the CPP task (preference, extinction, or reinstatement testing), nor did Mn affect progressive ratio responding (a measure of motivation). Interestingly, acquisition of a fixed ratio task was impaired in Mn-exposed rats, suggesting a deficit in procedural learning. In sum, these results indicate that postnatal Mn exposure causes persistent declines in various indices of presynaptic dopaminergic functioning. Mn-induced alterations in striatal functioning may have long-term impact on associative and nonassociative behavior. PMID:18485605

  7. The Vacuolar Manganese Transporter MTP8 Determines Tolerance to Iron Deficiency-Induced Chlorosis in Arabidopsis1[OPEN

    PubMed Central

    2016-01-01

    Iron (Fe) deficiency is a widespread nutritional disorder on calcareous soils. To identify genes involved in the Fe deficiency response, Arabidopsis (Arabidopsis thaliana) transfer DNA insertion lines were screened on a high-pH medium with low Fe availability. This approach identified METAL TOLERANCE PROTEIN8 (MTP8), a member of the Cation Diffusion Facilitator family, as a critical determinant for the tolerance to Fe deficiency-induced chlorosis, also on soil substrate. Subcellular localization to the tonoplast, complementation of a manganese (Mn)-sensitive Saccharomyces cerevisiae yeast strain, and Mn sensitivity of mtp8 knockout mutants characterized the protein as a vacuolar Mn transporter suitable to prevent plant cells from Mn toxicity. MTP8 expression was strongly induced on low-Fe as well as high-Mn medium, which were both strictly dependent on the transcription factor FIT, indicating that high-Mn stress induces Fe deficiency. mtp8 mutants were only hypersensitive to Fe deficiency when Mn was present in the medium, which further suggested an Mn-specific role of MTP8 during Fe limitation. Under those conditions, mtp8 mutants not only translocated more Mn to the shoot than did wild-type plants but suffered in particular from critically low Fe concentrations and, hence, Fe chlorosis, although the transcriptional Fe deficiency response was up-regulated more strongly in mtp8. The diminished uptake of Fe from Mn-containing low-Fe medium by mtp8 mutants was caused by an impaired ability to boost the ferric chelate reductase activity, which is an essential process in Fe acquisition. These findings provide a mechanistic explanation for the long-known interference of Mn in Fe nutrition and define the molecular processes by which plants alleviate this antagonism. PMID:26668333

  8. A Novel Metal Transporter Mediating Manganese Export (MntX) Regulates the Mn to Fe Intracellular Ratio and Neisseria meningitidis Virulence

    PubMed Central

    Veyrier, Frédéric J.; Boneca, Ivo G.; Cellier, Mathieu F.; Taha, Muhamed-Kheir

    2011-01-01

    Neisseria meningitidis (Nm) and N. gonorrhoeae (Ng) are adapted to different environments within their human host. If the basis of this difference has not yet been fully understood, previous studies (including our own data) have reported that, unlike Ng, Nm tolerates high manganese concentrations. As transition metals are essential regulators of cell growth and host pathogen interactions, we aimed to address mechanisms of Nm Mn2+ tolerance and its pathogenic consequences. Using bioinformatics, gene deletion and heterologous expression we identified a conserved bacterial manganese resistance factor MntX (formerly YebN). The predicted structure suggests that MntX represents a new family of transporters exporting Mn. In the Neisseria genus, this exporter is present and functional in all Nm isolates but it is mutated in a majority of Ng strains and commonly absent in nonpathogenic species. In Nm, Mn2+ export via MntX regulates the intracellular Mn/Fe ratio and protects against manganese toxicity that is exacerbated in low iron conditions. MntX is also important for N. meningitidis to resist killing by human serum and for survival in mice blood during septicemia. The present work thus points to new clues about Mn homeostasis, its interplay with Fe metabolism and the influence on N. meningitidis physiology and pathogenicity. PMID:21980287

  9. Magnetism and Transport in the Group-IV Dilute Magnetic Semiconductor Germanium(1-x) Manganese(x)

    NASA Astrophysics Data System (ADS)

    Dolph, Melissa Ann Commisso

    Dilute magnetic semiconductors (DMS) have gained interest over the past decade because of their potential applications in spintronics. DMS systems exhibit carriermediated ferromagnetism, a property which enables electric-field control over the magnetization. In this thesis, the DMS Ge1-xMn x was studied. Germanium (Ge) is a desirable semiconductor because of its high hole mobility and its compatibility with silicon. Manganese (Mn) was chosen for its exhibition of indirect ferromagnetic coupling. These properties are deemed necessary for the realization of a magnetic quantum-dot based device such as a magnetic spin switch. Ion implantation of Mn into Ge-on-insulator and molecular beam expitaxy (MBE) were two methods utilized to synthesize the studied Ge1-x Mnx thin films. Several of the Ge1-xMn x films were treated with rapid thermal annealing (RTA) or pulsed laser melting (PLM) in an attempt to improve the crystallinity and make more of the Mn ferromagnetically active. Of all the Ge1-xMn x systems studied, those that exhibited correlated magnetic and magneto-transport properties were those with hole concentrations on the order of 1019 --1020 holes/cm3. Although these systems exhibited robust magneto-transport properties, electric-field biasing proved ineffective at modulating the carrier concentration and ultimately the magnetization as monitored by the ordinary and anomalous Hall effects and the resistivity. The inefficiency of the electric gating was attributed to localized trap states which reside in the energy band gap of the defect-plagued Ge semiconductor. If crystallinity is a prerequisite for gatability, PLM may prove useful as it was found to restore the single crystal structure damaged during Mn implantation. However, PLM resulted in an undesirable segregation of Mn toward the surface of the film (as observed by secondary ion mass spectrometry (SIMS)); a decrease in the saturation magnetization after PLM was attributed to this segregation. The information

  10. Manganese uptake in marine bacteria; the novel MntX transporter is widespread in Roseobacters, Vibrios, Alteromonadales and the SAR11 and SAR116 clades

    PubMed Central

    Green, Robert T; Todd, Jonathan D; Johnston, Andrew W B

    2013-01-01

    We showed that two very different manganese transporters occur in various important genera of marine bacteria. The ABC transporter encoded by sitABCD of the model Roseobacter-clade bacterium Ruegeria pomeroyi DSS-3 is required for Mn2+ import and was repressed by the Mur (Manganese uptake regulator) transcriptional regulator in Mn-replete media. Most genome-sequenced Roseobacter strains contain SitABCD, which are in at least two sub-groups, judged by their amino-acid sequences. However, a few Roseobacters, for example, Roseovarius nubinhibens, lack sitABCD, but these contain another gene, mntX, which encodes a predicted inner membrane polypeptide and is preceded by cis-acting Mur-responsive MRS sequences. It was confirmed directly that mntX of Roseovarius nubinhibens encodes a manganese transporter that was required for growth in Mn-depleted media and that its expression was repressed by Mur in Mn-replete conditions. MntX homologues occur in the deduced proteomes of several bacterial species. Strikingly, all of these live in marine habitats, but are in distantly related taxonomic groups, in the γ- and α-proteobacteria. Notably, MntX was prevalent in nearly all strains of Vibrionales, including the important pathogen, Vibrio cholerae. It also occurs in a strain of the hugely abundant Candidatus Pelagibacter (SAR11), and in another populous marine bacterium, Candidatus Puniceispirillum marinum (SAR116). Consistent with this, MntX was abundant in marine bacterial metagenomes, with one sub-type occurring in an as-yet unknown bacterial clade. PMID:23190726

  11. Deficits in axonal transport in hippocampal-based circuitry and the visual pathway in APP knock-out animals witnessed by manganese enhanced MRI

    PubMed Central

    Gallagher, Joseph J.; Zhang, Xiaowei; Ziomek, Greg; Jacobs, Russell E.; Bearer, Elaine L.

    2012-01-01

    Mounting evidence implicates axonal transport defects, typified by the presence of axonal varicosities with aberrant accumulations of cargo, as an early event in Alzheimer’s disease (AD) pathogenesis. Work identifying amyloid precursor protein (APP) as a vesicular motor receptor for anterograde axonal transport further implicates axonal transport in AD. Manganese-enhanced MRI (MEMRI) detects axonal transport dynamics in preclinical studies. Here we pursue an understanding of the role of APP in axonal transport in the central nervous system by applying MEMRI to hippocampal circuitry and to the visual pathway in living mice homozygous for either wild type or a deletion in the APP gene (n = 12 for each genotype). Following intra-ocular or stereotaxic hippocampal injection, we performed time-lapse MRI to detect Mn2+ transport. Three dimensional whole brain datasets were compared on a voxel-wise basis using within-group pair-wise analysis. Quantification of transport to structures connected to injection sites via axonal fiber tracts was also performed. Histology confirmed consistent placement of hippocampal injections and no observable difference in glial-response to the injections. APP −/− mice had significantly reduced transport from the hippocampus to the septal nuclei and amygdala after 7 hours and reduced transport to the contralateral hippocampus after 25 hours; axonal transport deficits in the APP −/− animals were also identified in the visual pathway. These data support a system-wide role for APP in axonal transport within the central nervous system and demonstrate the power of MEMRI for assessing neuronal circuitry involved in memory and learning. PMID:22500926

  12. A mutagenic study identifying critical residues for the structure and function of rice manganese transporter OsMTP8.1

    PubMed Central

    Chen, Xi; Li, Jiyu; Wang, Lihua; Ma, Gang; Zhang, Wei

    2016-01-01

    Rice (Oryza sativa) MTP8.1 (OsMTP8.1) is a tonoplast-localized manganese transporter of the cation diffusion facilitator family. Here we present a structure-function analysis of OsMTP8.1 based on the site-directed and random mutagenesis and complementation assays in manganese hypersensitive yeast, in combination with three-dimensional (3D) structure modeling based on the crystal structure of the Escherichia coli CDF family member, EcYiiP. Two metal-binding sites are conserved in OsMTP8.1 with EcYiiP, one is between transmembrane helices TM2 and TM5, the other is the cytoplasmic C-terminus. In addition to these two metal-binding sites, there may exist other Mn-binding sites such as that at the very end of the CTD. Two residues (R167 and L296) may play an important role for the hinge-like movement of CTDs. Several mutations such as E357A and V374D may affect dimer formation, and S132A may induce a conformational change, resulting in a loss of transport function or modification in metal selectivity. The N-terminus of OsMTP8.1 was not functional for Mn transport activity, and the real function of NTD remains to be investigated in the future. The findings of the present study illustrate the structure-function relationship of OsMTP8.1 in Mn transport activity, which may also be applied to other plant Mn-CDF proteins. PMID:27555514

  13. Coordination between manganese and nitrogen within the ligands in the manganese complexes facilitates the reconstitution of the water-oxidizing complex in manganese-depleted photosystem II preparations.

    PubMed

    Li, Shuqin; Chen, Guiying; Han, Guangye; Ling, Lin; Huang, Deguang; Khorobrykh, A A; Zharmukhamedov, S K; Liu, Qiutian; Klimov, V V; Kuang, Tingyun

    2006-09-01

    The water-oxidizing complex (WOC) within photosystem II (PSII) can be reconstituted with synthetic manganese complexes by a process called photoactivation; however, the key factors affecting the efficiency of synthetic manganese complexes in reconstitution of electron transport and oxygen evolution activity in manganese-depleted PSII remain unclear. In the present study, four complexes with different manganese coordination environments were used to reconstitute the WOC, and an interesting relationship was found between the coordination environment of the manganese atom in the complexes and their efficiency in restoring electron transport and oxygen evolution. If Mn(II) is coordinated to nitrogen atoms within the ligand, it can restore significant rates of electron transport and oxygen evolution; however, if the manganese atom is coordinated only to oxygen atoms instead of nitrogen atoms, it has no capability to restore electron transport and oxygen evolution. So, our results demonstrate that the capability of manganese complexes to reconstitute the WOC is mainly determined by the coordination between nitrogen atoms from ligands and the manganese atom. It is suggested from our results that the ligation between the nitrogen atom and the manganese atom within the manganese complex facilitates the photoligation of the manganese atom to histidyl residues on the apo-protein in manganese-depleted PSII during photoactivation. PMID:16791637

  14. Relative contribution of CTR1 and DMT1 in copper transport by the blood–CSF barrier: Implication in manganese-induced neurotoxicity

    SciTech Connect

    Zheng, Gang; Chen, Jingyuan; Zheng, Wei

    2012-05-01

    The homeostasis of copper (Cu) in the cerebrospinal fluid (CSF) is partially regulated by the Cu transporter-1 (CTR1) and divalent metal transporter-1 (DMT1) at the blood–CSF barrier (BCB) in the choroid plexus. Data from human and animal studies suggest an increased Cu concentration in blood, CSF, and brains following in vivo manganese (Mn) exposure. This study was designed to investigate the relative role of CTR1 and DMT1 in Cu transport under normal or Mn-exposed conditions using an immortalized choroidal Z310 cell line. Mn exposure in vitro resulted in an increased cellular {sup 64}Cu uptake and the up-regulation of both CTR1 and DMT1. Knocking down CTR1 by siRNA counteracted the Mn-induced increase of {sup 64}Cu uptake, while knocking down DMT1 siRNA resulted in an increased cellular {sup 64}Cu uptake in Mn-exposed cells. To distinguish the roles of CTR1 and DMT1 in Cu transport, the Z310 cell-based tetracycline (Tet)-inducible CTR1 and DMT1 expression cell lines were developed, namely iZCTR1 and iZDMT1 cells, respectively. In iZCTR1 cells, Tet induction led to a robust increase (25 fold) of {sup 64}Cu uptake with the time course corresponding to the increased CTR1. Induction of DMT1 by Tet in iZDMT1 cells, however, resulted in only a slight increase of {sup 64}Cu uptake in contrast to a substantial increase in DMT1 mRNA and protein expression. These data indicate that CTR1, but not DMT1, plays an essential role in transporting Cu by the BCB in the choroid plexus. Mn-induced cellular overload of Cu at the BCB is due, primarily, to Mn-induced over-expression of CTR1. -- Highlights: ► This study compares the relative role of CTR1 and DMT1 in Cu transport by the BCB. ► Two novel tetracycline-inducible CTR1 and DMT1 expression cell lines are created. ► CTR1, but not DMT1, plays an essential role in transporting Cu by the BCB. ► Mn-induced cellular Cu overload is due to its induction of CTR1 rather than DMT1. ► Induction of CTR1 by Mn in the BCB

  15. Facilitated transport channels in carbon nanotube/carbon nanofiber hierarchical composites decorated with manganese dioxide for flexible supercapacitors

    NASA Astrophysics Data System (ADS)

    Wang, Tao; Song, Dengfei; Zhao, Hao; Chen, Jiayi; Zhao, Changhui; Chen, Lulu; Chen, Wanjun; Zhou, Jinyuan; Xie, Erqing

    2015-01-01

    Freestanding carbon nanotube/carbon nanofiber (CNT/CNF) composites are prepared using electrospun CNFs as skeletons in a tubular chemical vapor deposition system. The obtained CNT/CNF composites show a hierarchical structure with a high special surface area, a high conductance (1250 S cm-1 for a 10 mm × 20 mm sample), and a high flexibility. After coated with manganese dioxide (MnO2) via an in-situ redox deposition for 0.5 h (∼0.33 mg), the CNT/CNF/MnO2 electrodes show a high specific capacitance of 517 F g-1 at a scan rate of 5 mV s-1, which is about 5.6 time higher than that CNF/MnO2-0.25 h ones with MnO2 of ∼0.36 mg. Moreover, this CNT/CNF/MnO2 electrodes show a much higher rate capability (57% at current density of 14 A g-1) than CNF/MnO2 ones (24% at 14 A g-1), and also show a higher cycling stability (maintaining 75% of the initial capacitance at cycle number of 1000). In addition, the symmetric supercapacitor assembled using two piece CNT/CNF/MnO2 electrodes shows their maximum energy density of 3.88 Wh kg-1 at power density of 7000 W kg-1. The capacitance of the assembled capacitor maintains 70% after 100 bending cycles, indicating a good flexibility. These enhancements in EC performances should be due to our designed hierarchical structures. It is suggested that such freestanding flexible CNFs/CNTs/MnO2 hierarchical composites are highly promising for high-performance flexible supercapacitors.

  16. Iron, copper, zinc, and manganese transport and regulation in pathogenic Enterobacteria: correlations between strains, site of infection and the relative importance of the different metal transport systems for virulence

    PubMed Central

    Porcheron, Gaëlle; Garénaux, Amélie; Proulx, Julie; Sabri, Mourad; Dozois, Charles M.

    2013-01-01

    For all microorganisms, acquisition of metal ions is essential for survival in the environment or in their infected host. Metal ions are required in many biological processes as components of metalloproteins and serve as cofactors or structural elements for enzymes. However, it is critical for bacteria to ensure that metal uptake and availability is in accordance with physiological needs, as an imbalance in bacterial metal homeostasis is deleterious. Indeed, host defense strategies against infection either consist of metal starvation by sequestration or toxicity by the highly concentrated release of metals. To overcome these host strategies, bacteria employ a variety of metal uptake and export systems and finely regulate metal homeostasis by numerous transcriptional regulators, allowing them to adapt to changing environmental conditions. As a consequence, iron, zinc, manganese, and copper uptake systems significantly contribute to the virulence of many pathogenic bacteria. However, during the course of our experiments on the role of iron and manganese transporters in extraintestinal Escherichia coli (ExPEC) virulence, we observed that depending on the strain tested, the importance of tested systems in virulence may be different. This could be due to the different set of systems present in these strains, but literature also suggests that as each pathogen must adapt to the particular microenvironment of its site of infection, the role of each acquisition system in virulence can differ from a particular strain to another. In this review, we present the systems involved in metal transport by Enterobacteria and the main regulators responsible for their controlled expression. We also discuss the relative role of these systems depending on the pathogen and the tissues they infect. PMID:24367764

  17. Autosomal-Recessive Intellectual Disability with Cerebellar Atrophy Syndrome Caused by Mutation of the Manganese and Zinc Transporter Gene SLC39A8.

    PubMed

    Boycott, Kym M; Beaulieu, Chandree L; Kernohan, Kristin D; Gebril, Ola H; Mhanni, Aziz; Chudley, Albert E; Redl, David; Qin, Wen; Hampson, Sarah; Küry, Sébastien; Tetreault, Martine; Puffenberger, Erik G; Scott, James N; Bezieau, Stéphane; Reis, André; Uebe, Steffen; Schumacher, Johannes; Hegele, Robert A; McLeod, D Ross; Gálvez-Peralta, Marina; Majewski, Jacek; Ramaekers, Vincent T; Nebert, Daniel W; Innes, A Micheil; Parboosingh, Jillian S; Abou Jamra, Rami

    2015-12-01

    Manganese (Mn) and zinc (Zn) are essential divalent cations used by cells as protein cofactors; various human studies and animal models have demonstrated the importance of Mn and Zn for development. Here we describe an autosomal-recessive disorder in six individuals from the Hutterite community and in an unrelated Egyptian sibpair; the disorder is characterized by intellectual disability, developmental delay, hypotonia, strabismus, cerebellar atrophy, and variable short stature. Exome sequencing in one affected Hutterite individual and the Egyptian family identified the same homozygous variant, c.112G>C (p.Gly38Arg), affecting a conserved residue of SLC39A8. The affected Hutterite and Egyptian individuals did not share an extended common haplotype, suggesting that the mutation arose independently. SLC39A8 is a member of the solute carrier gene family known to import Mn, Zn, and other divalent cations across the plasma membrane. Evaluation of these two metal ions in the affected individuals revealed variably low levels of Mn and Zn in blood and elevated levels in urine, indicating renal wasting. Our findings identify a human Mn and Zn transporter deficiency syndrome linked to SLC39A8, providing insight into the roles of Mn and Zn homeostasis in human health and development. PMID:26637978

  18. The Role of Transition Metal Transporters for Iron, Zinc, Manganese, and Copper in the Pathogenesis of Yersinia pestis

    PubMed Central

    Perry, Robert D.; Bobrov, Alexander G.; Fetherston, Jacqueline D.

    2015-01-01

    Yersinia pestis, the causative agent of bubonic, septicemic and pneumonic plague, encodes a multitude of Fe transport systems. Some of these are defective due to frameshift or IS element insertions, while others are functional in vitro but have no established role in causing infections. Indeed only 3 Fe transporters (Ybt, Yfe and Feo) have been shown to be important in at least one form of plague. The yersiniabactin (Ybt) system is essential in the early dermal/lymphatic stages of bubonic plague, irrelevant in the septicemic stage, and critical in pneumonic plague. Two Mn transporters have been characterized (Yfe and MntH). These two systems play a role in bubonic plague but the double yfe mntH mutant is fully virulent in a mouse model of pneumonic plague. The same in vivo phenotype occurs with a mutant lacking two (Yfe and Feo) of four ferrous transporters. A role for the Ybt siderophore in Zn acquisition has been revealed. Ybt-dependent Zn acquisition uses a transport system completely independent of the Fe-Ybt uptake system. Together Ybt components and ZnuABC play a critical role in Zn acquisition in vivo. Single mutants in either system retain high virulence in a mouse model of septicemic plague while the double mutant is completely avirulent. PMID:25891079

  19. Electrokinetic remediation of manganese and ammonia nitrogen from electrolytic manganese residue.

    PubMed

    Shu, Jiancheng; Liu, Renlong; Liu, Zuohua; Du, Jun; Tao, Changyuan

    2015-10-01

    Electrolytic manganese residue (EMR) is a solid waste found in filters after sulphuric acid leaching of manganese carbonate ore, which mainly contains manganese and ammonia nitrogen and seriously damages the ecological environment. This work demonstrated the use of electrokinetic (EK) remediation to remove ammonia nitrogen and manganese from EMR. The transport behavior of manganese and ammonia nitrogen from EMR during electrokinetics, Mn fractionation before and after EK treatment, the relationship between Mn fractionation and transport behavior, as well as the effects of electrolyte and pretreatment solutions on removal efficiency and energy consumption were investigated. The results indicated that the use of H2SO4 and Na2SO4 as electrolytes and pretreatment of EMR with citric acid and KCl can reduce energy consumption, and the removal efficiencies of manganese and ammonia nitrogen were 27.5 and 94.1 %, respectively. In these systems, electromigration and electroosmosis were the main mechanisms of manganese and ammonia nitrogen transport. Moreover, ammonia nitrogen in EMR reached the regulated level, and the concentration of manganese in EMR could be reduced from 455 to 37 mg/L. In general, the electrokinetic remediation of EMR is a promising technology in the future. PMID:26062467

  20. SLC30A10 Is a Cell Surface-Localized Manganese Efflux Transporter, and Parkinsonism-Causing Mutations Block Its Intracellular Trafficking and Efflux Activity

    PubMed Central

    Leyva-Illades, Dinorah; Chen, Pan; Zogzas, Charles E.; Hutchens, Steven; Mercado, Jonathan M.; Swaim, Caleb D.; Morrisett, Richard A.; Bowman, Aaron B.

    2014-01-01

    Manganese (Mn) is an essential metal, but elevated cellular levels are toxic and may lead to the development of an irreversible parkinsonian-like syndrome that has no treatment. Mn-induced parkinsonism generally occurs as a result of exposure to elevated Mn levels in occupational or environmental settings. Additionally, patients with compromised liver function attributable to diseases, such as cirrhosis, fail to excrete Mn and may develop Mn-induced parkinsonism in the absence of exposure to elevated Mn. Recently, a new form of familial parkinsonism was reported to occur as a result of mutations in SLC30A10. The cellular function of SLC30A10 and the mechanisms by which mutations in this protein cause parkinsonism are unclear. Here, using a combination of mechanistic and functional studies in cell culture, Caenorhabditis elegans, and primary midbrain neurons, we show that SLC30A10 is a cell surface-localized Mn efflux transporter that reduces cellular Mn levels and protects against Mn-induced toxicity. Importantly, mutations in SLC30A10 that cause familial parkinsonism blocked the ability of the transporter to traffic to the cell surface and to mediate Mn efflux. Although expression of disease-causing SLC30A10 mutations were not deleterious by themselves, neurons and worms expressing these mutants exhibited enhanced sensitivity to Mn toxicity. Our results provide novel insights into the mechanisms involved in the onset of a familial form of parkinsonism and highlight the possibility of using enhanced Mn efflux as a therapeutic strategy for the potential management of Mn-induced parkinsonism, including that occurring as a result of mutations in SLC30A10. PMID:25319704

  1. Replacement of a cytosolic copper/zinc superoxide dismutase by a novel cytosolic manganese superoxide dismutase in crustaceans that use copper (haemocyanin) for oxygen transport.

    PubMed Central

    Brouwer, Marius; Hoexum Brouwer, Thea; Grater, Walter; Brown-Peterson, Nancy

    2003-01-01

    The blue crab, Callinectes sapidus, which uses the copper-dependent protein haemocyanin for oxygen transport, lacks the ubiquitous cytosolic copper-dependent enzyme copper/zinc superoxide dismutase (Cu,ZnSOD) as evidenced by undetectable levels of Cu,ZnSOD activity, protein and mRNA in the hepatopancreas (the site of haemocyanin synthesis) and gills. Instead, the crab has an unusual cytosolic manganese SOD (cytMnSOD), which is retained in the cytosol, because it lacks a mitochondrial transit peptide. A second familiar MnSOD is present in the mitochondria (mtMnSOD). This unique phenomenon occurs in all Crustacea that use haemocyanin for oxygen transport. Molecular phylogeny analysis suggests the MnSOD gene duplication is as old as the origin of the arthropod phylum. cytMnSOD activity in the hepatopancreas changes during the moulting cycle of the crab. Activity is high in intermoult crabs and non-detectable in postmoult papershell crabs. mtMnSOD is present in all stages of the moulting cycle. Despite the lack of cytCu,ZnSOD, crabs have an extracellular Cu,ZnSOD (ecCu,ZnSOD) that is produced by haemocytes, and is part of a large, approx. 160 kDa, covalently-linked protein complex. ecCu,ZnSOD is absent from the hepatopancreas of intermoult crabs, but appears in this tissue at premoult. However, no ecCu,ZnSOD mRNA can be detected, suggesting that the protein is recruited from the haemolymph. Screening of different taxa of the arthropod phylum for Cu,ZnSOD activity shows that those crustaceans that use haemoglobin for oxygen transport have retained cytCu,ZnSOD. It appears, therefore, that the replacement of cytCu,ZnSOD with cytMnSOD is part of an adaptive response to the dynamic, haemocyanin-linked, fluctuations in copper metabolism that occur during the moulting cycle of the crab. PMID:12769817

  2. Cross-sectional study of expression of divalent metal transporter-1, transferrin, and hepcidin in blood of smelters who are occupationally exposed to manganese

    PubMed Central

    Zhou, Yan; Yu, Changyin; Chen, Jian; Shi, Xiujuan; Zhang, Yanshu

    2016-01-01

    Background Manganese (Mn) is widely used in industries including the manufacture of Mn-iron (Fe) alloy. Occupational Mn overexposure causes manganism. Mn is known to affect Fe metabolism; this study was designed to test the hypothesis that workers exposed to Mn may have an altered expression of mRNAs encoding proteins in Fe metabolism. Methods Workers occupationally exposed to Mn (n = 71) from a Mn–Fe alloy factory and control workers without Mn-exposure (n = 48) from a pig-iron plant from Zunyi, China, were recruited for this study. Blood samples were collected into Trizol-containing tubes. Total RNA was isolated, purified, and subjected to real-time RT-PCR analysis. Metal concentrations were quantified by atomic absorption spectrophotometry. Results Working environment and genetic background of both groups were similar except for marked differences in airborne Mn concentrations (0.18 mg/m3 in Mn–Fe alloy factory vs. 0.0022 mg/m3 in pig-Fe plant), and in blood Mn levels (34.3 µg/L vs. 10.4 µg/L). Mn exposure caused a significant decrease in the expression of divalent metal transporter-1 (DMT1), transferrin (Tf) and hepcidin by 58.2%, 68.5% and 61.5%, respectively, as compared to controls, while the expression of transferrin receptor (TfR) was unaltered. Linear regression analysis revealed that expressions of DMT1, Tf and hepcidin were inversely correlated with the accumulative Mn exposure; the correlation coefficients (r) are −0.47, −0.54, and −0.49, respectively (p < 0.01). Conclusion The data suggest that occupational Mn exposure causes decreased expressions of DMT1, Tf and hepcidin in blood cells; the finding will help understand the mechanism underlying Mn exposure-associated alteration in Fe homeostasis among workers.

  3. Cucumber metal transport protein MTP8 confers increased tolerance to manganese when expressed in yeast and Arabidopsis thaliana

    PubMed Central

    Migocka, Magdalena; Papierniak, Anna; Maciaszczyk-Dziubińska, Ewa; Poździk, Piotr; Posyniak, Ewelina; Garbiec, Arnold; Filleur, Sophie

    2014-01-01

    Cation diffusion facilitator (CDF) proteins are ubiquitous divalent cation transporters that have been proved to be essential for metal homeostasis and tolerance in Archaebacteria, Bacteria, and Eukaryota. In plants, CDFs are designated as metal tolerance proteins (MTPs). Due to the lack of genomic resources, studies on MTPs in other plants, including cultivated crops, are lacking. Here, the identification and organization of genes encoding members of the MTP family in cucumber are described. The first functional characterization of a cucumber gene encoding a member of the Mn-CDF subgroup of CDF proteins, designated as CsMTP8 based on the highest homology to plant MTP8, is also presented. The expression of CsMTP8 in Saccharomyces cerevisiae led to increased Mn accumulation in yeast cells and fully restored the growth of mutants hypersensitive to Mn in Mn excess. Similarly, the overexpression of CsMTP8 in Arabidopsis thaliana enhanced plant tolerance to high Mn in nutrition media as well as the accumulation of Mn in plant tissues. When fused to green fluorescent protein (GFP), CsMTP8 localized to the vacuolar membranes in yeast cells and to Arabidopsis protoplasts. In cucumber, CsMTP8 was expressed almost exclusively in roots, and the level of gene transcript was markedly up-regulated or reduced under elevated Mn or Mn deficiency, respectively. Taken together, the results suggest that CsMTP8 is an Mn transporter localized in the vacuolar membrane, which participates in the maintenance of Mn homeostasis in cucumber root cells. PMID:25039075

  4. Investigation of Transport Anomalies in LANTHANUM(1-Y) STRONTIUM(Y)CHROMIUM(1-X)MANGANESE(X)OXYGEN(3)

    NASA Astrophysics Data System (ADS)

    Raffaelle, Ryne Patrick

    1990-08-01

    This dissertation presents an investigation of several anomalies associated with electronic transport in the La_{1-y}Sr_{y}Cr_{1-x}Mn_{x} O_3 series. The specific anomaly which prompted this study was a large decrease in electrical conductivity when small amounts of Mn were substituted for Cr in LaCrO _3. This decrease was followed by a sharp rise in the conductivity as the Mn content is increased. This conductivity minimum was unexpected due to the fact that LaMnO_3 was believed to have the same conduction mechanism (small polarons) and nearly the same activation energy as LaCrO_3, but a larger conductivity. A detailed set of electrical conductivity measurements was performed on the LaCr_{1-x}Mn_{x} O_3 series. The conductivity minimum has been attributed to an energy difference between polarons located on Cr or Mn ions as a result of this study. A crossover from multiple-trapping to percolation among energetically lower Mn sites qualitatively explained the conductivity of the LaCr_{1-x}Mn _{x}O _3 series. This explanation combined aspects from traditionally separate models of disordered electronic transport. Thermopower measurements were performed on the LaCr_{1-x}Mn _{x}O _3 series and a similar series in which 10 mol% Sr was substituted for La to investigate the crossover dependence on the carrier concentration. The concentration of small polarons in the Mn end members is much larger than was expected from naturally occurring structural defects. The expected increase in carrier concentration with Sr substitution was suppressed in nearly all Mn containing samples. This work was concluded by suggesting a possible Mn ^{+2}-Mn^{+4 } electronic structure which seems to resolve these problems.

  5. Competition for Manganese at the Host-Pathogen Interface.

    PubMed

    Kelliher, J L; Kehl-Fie, T E

    2016-01-01

    Transition metals such as manganese are essential nutrients for both pathogen and host. Vertebrates exploit this necessity to combat invading microbes by restricting access to these critical nutrients, a defense known as nutritional immunity. During infection, the host uses several mechanisms to impose manganese limitation. These include removal of manganese from the phagolysosome, sequestration of extracellular manganese, and utilization of other metals to prevent bacterial acquisition of manganese. In order to cause disease, pathogens employ a variety of mechanisms that enable them to adapt to and counter nutritional immunity. These adaptations include, but are likely not limited to, manganese-sensing regulators and high-affinity manganese transporters. Even though successful pathogens can overcome host-imposed manganese starvation, this defense inhibits manganese-dependent processes, reducing the ability of these microbes to cause disease. While the full impact of host-imposed manganese starvation on bacteria is unknown, critical bacterial virulence factors such as superoxide dismutases are inhibited. This chapter will review the factors involved in the competition for manganese at the host-pathogen interface and discuss the impact that limiting the availability of this metal has on invading bacteria. PMID:27571690

  6. Three-Dimensional Structure and Biophysical Characterization of Staphylococcus aureus Cell Surface Antigen-Manganese Transporter MntC

    SciTech Connect

    Gribenko, Alexey; Mosyak, Lidia; Ghosh, Sharmistha; Parris, Kevin; Svenson, Kristine; Moran, Justin; Chu, Ling; Li, Sheng; Liu, Tong; Woods, Jr., Virgil L.; Jansen, Kathrin U.; Green, Bruce A.; Anderson, Annaliesa S.; Matsuka, Yury V.

    2013-08-23

    MntC is a metal-binding protein component of the Mn2 +-specific mntABC transporter from the pathogen Staphylococcus aureus. The protein is expressed during the early stages of infection and was proven to be effective at reducing both S. aureus and Staphylococcus epidermidis infections in a murine animal model when used as a vaccine antigen. MntC is currently being tested in human clinical trials as a component of a multiantigen vaccine for the prevention of S. aureus infections. To better understand the biological function of MntC, we are providing structural and biophysical characterization of the protein in this work. The three-dimensional structure of the protein was solved by X-ray crystallography at 2.2 Å resolution and suggests two potential metal binding modes, which may lead to reversible as well as irreversible metal binding. Precise Mn2 +-binding affinity of the protein was determined from the isothermal titration calorimetry experiments using a competition approach. Differential scanning calorimetry experiments confirmed that divalent metals can indeed bind to MntC reversibly as well as irreversibly. Finally, Mn2 +-induced structural and dynamics changes have been characterized using spectroscopic methods and deuterium–hydrogen exchange mass spectroscopy. Results of the experiments show that these changes are minimal and are largely restricted to the structural elements involved in metal coordination. Therefore, it is unlikely that antibody binding to this antigen will be affected by the occupancy of the metal-binding site by Mn2 +.

  7. Manganese homeostasis in the nervous system.

    PubMed

    Chen, Pan; Chakraborty, Sudipta; Mukhopadhyay, Somshuvra; Lee, Eunsook; Paoliello, Monica M B; Bowman, Aaron B; Aschner, Michael

    2015-08-01

    Manganese (Mn) is an essential heavy metal that is naturally found in the environment. Daily intake through dietary sources provides the necessary amount required for several key physiological processes, including antioxidant defense, energy metabolism, immune function and others. However, overexposure from environmental sources can result in a condition known as manganism that features symptomatology similar to Parkinson's disease (PD). This disorder presents with debilitating motor and cognitive deficits that arise from a neurodegenerative process. In order to maintain a balance between its essentiality and neurotoxicity, several mechanisms exist to properly buffer cellular Mn levels. These include transporters involved in Mn uptake, and newly discovered Mn efflux mechanisms. This review will focus on current studies related to mechanisms underlying Mn import and export, primarily the Mn transporters, and their function and roles in Mn-induced neurotoxicity. Though and essential metal, overexposure to manganese may result in neurodegenerative disease analogous to Parkinson's disease. Manganese homeostasis is tightly regulated by transporters, including transmembrane importers (divalent metal transporter 1, transferrin and its receptor, zinc transporters ZIP8 and Zip14, dopamine transporter, calcium channels, choline transporters and citrate transporters) and exporters (ferroportin and SLC30A10), as well as the intracellular trafficking proteins (SPCA1 and ATP12A2). A manganese-specific sensor, GPP130, has been identified, which affords means for monitoring intracellular levels of this metal. PMID:25982296

  8. Manganese laser using manganese chloride as lasant

    NASA Technical Reports Server (NTRS)

    Chen, C. J.

    1974-01-01

    A manganese vapor laser utilizing manganese chloride as a lasant has been observed and investigated. Lasing is attained by means of two consecutive electrical discharges. The maximum laser output is obtained at a vapor pressure of about 3 torr, a temperature of 680 C, and a time delay between electrical discharges of 150 microsec. The maximum energy density is 1.3 microjoule per cu cm.

  9. Manganese uptake of imprinted polymers

    DOE Data Explorer

    Susanna Ventura

    2015-09-30

    Batch tests of manganese imprinted polymers of variable composition to assess their ability to extract lithium and manganese from synthetic brines at T=45C . Data on manganese uptake for two consecutive cycles are included.

  10. BIOLOGICAL EFFECTS OF MANGANESE

    EPA Science Inventory

    The biological effects of manganese were studied in a town on the coast of Dalmatia in which a ferromanganese plant has been operating since before World War II. The study focused on the question of whether the exposure to manganese can cause a higher incidence of respiratory dis...

  11. A light-dependent mechanism for massive accumulation of manganese in the photosynthetic bacterium Synechocystis sp. PCC 6803.

    PubMed

    Keren, Nir; Kidd, Matthew J; Penner-Hahn, James E; Pakrasi, Himadri B

    2002-12-17

    Manganese is an essential micronutrient for many organisms. Because of its unique role in the water oxidizing activity of photosystem II, manganese is required for photosynthetic growth in plants and cyanobacteria. Here we report on the mechanism of manganese uptake in the cyanobacterium Synechocystis sp. PCC 6803. Cells grown in 9 microM manganese-containing medium accumulate up to 1 x 10(8) manganese atoms/cell, bound to the outer membrane (pool A). This pool could be released by EDTA treatment. Accumulation of manganese in pool A was energized by photosynthetic electron flow. Moreover, collapsing the membrane potential resulted in the immediate release of this manganese pool. The manganese in this pool is mainly Mn(II) in a six-coordinate distorted environment. A distinctly different pool of manganese, pool B ( approximately 1.5 x 10(6) atoms/cell), could not be extracted by EDTA. Transport into pool B was light-independent and could be detected only under limiting manganese concentrations (1 nM). Evidently, manganese uptake in Synechocystis 6803 cells occurs in two steps. First, manganese accumulates in the outer membrane (pool A) in a membrane potential-dependent process. Next, manganese is transported through the inner membrane into pool B. We propose that pool A serves as a store that allows the cells to overcome transient limitations in manganese in the environment. PMID:12475258

  12. Mutations in SLC39A14 disrupt manganese homeostasis and cause childhood-onset parkinsonism-dystonia.

    PubMed

    Tuschl, Karin; Meyer, Esther; Valdivia, Leonardo E; Zhao, Ningning; Dadswell, Chris; Abdul-Sada, Alaa; Hung, Christina Y; Simpson, Michael A; Chong, W K; Jacques, Thomas S; Woltjer, Randy L; Eaton, Simon; Gregory, Allison; Sanford, Lynn; Kara, Eleanna; Houlden, Henry; Cuno, Stephan M; Prokisch, Holger; Valletta, Lorella; Tiranti, Valeria; Younis, Rasha; Maher, Eamonn R; Spencer, John; Straatman-Iwanowska, Ania; Gissen, Paul; Selim, Laila A M; Pintos-Morell, Guillem; Coroleu-Lletget, Wifredo; Mohammad, Shekeeb S; Yoganathan, Sangeetha; Dale, Russell C; Thomas, Maya; Rihel, Jason; Bodamer, Olaf A; Enns, Caroline A; Hayflick, Susan J; Clayton, Peter T; Mills, Philippa B; Kurian, Manju A; Wilson, Stephen W

    2016-01-01

    Although manganese is an essential trace metal, little is known about its transport and homeostatic regulation. Here we have identified a cohort of patients with a novel autosomal recessive manganese transporter defect caused by mutations in SLC39A14. Excessive accumulation of manganese in these patients results in rapidly progressive childhood-onset parkinsonism-dystonia with distinctive brain magnetic resonance imaging appearances and neurodegenerative features on post-mortem examination. We show that mutations in SLC39A14 impair manganese transport in vitro and lead to manganese dyshomeostasis and altered locomotor activity in zebrafish with CRISPR-induced slc39a14 null mutations. Chelation with disodium calcium edetate lowers blood manganese levels in patients and can lead to striking clinical improvement. Our results demonstrate that SLC39A14 functions as a pivotal manganese transporter in vertebrates. PMID:27231142

  13. Mutations in SLC39A14 disrupt manganese homeostasis and cause childhood-onset parkinsonism–dystonia

    PubMed Central

    Tuschl, Karin; Meyer, Esther; Valdivia, Leonardo E.; Zhao, Ningning; Dadswell, Chris; Abdul-Sada, Alaa; Hung, Christina Y.; Simpson, Michael A.; Chong, W. K.; Jacques, Thomas S.; Woltjer, Randy L.; Eaton, Simon; Gregory, Allison; Sanford, Lynn; Kara, Eleanna; Houlden, Henry; Cuno, Stephan M.; Prokisch, Holger; Valletta, Lorella; Tiranti, Valeria; Younis, Rasha; Maher, Eamonn R.; Spencer, John; Straatman-Iwanowska, Ania; Gissen, Paul; Selim, Laila A. M.; Pintos-Morell, Guillem; Coroleu-Lletget, Wifredo; Mohammad, Shekeeb S.; Yoganathan, Sangeetha; Dale, Russell C.; Thomas, Maya; Rihel, Jason; Bodamer, Olaf A.; Enns, Caroline A.; Hayflick, Susan J.; Clayton, Peter T.; Mills, Philippa B.; Kurian, Manju A.; Wilson, Stephen W.

    2016-01-01

    Although manganese is an essential trace metal, little is known about its transport and homeostatic regulation. Here we have identified a cohort of patients with a novel autosomal recessive manganese transporter defect caused by mutations in SLC39A14. Excessive accumulation of manganese in these patients results in rapidly progressive childhood-onset parkinsonism–dystonia with distinctive brain magnetic resonance imaging appearances and neurodegenerative features on post-mortem examination. We show that mutations in SLC39A14 impair manganese transport in vitro and lead to manganese dyshomeostasis and altered locomotor activity in zebrafish with CRISPR-induced slc39a14 null mutations. Chelation with disodium calcium edetate lowers blood manganese levels in patients and can lead to striking clinical improvement. Our results demonstrate that SLC39A14 functions as a pivotal manganese transporter in vertebrates. PMID:27231142

  14. O-atom transport catalysis by neutral manganese oxide clusters in the gas phase: Reactions with CO, C2H4, NO2, and O2

    NASA Astrophysics Data System (ADS)

    Yin, Shi; Wang, Zhechen; Bernstein, Elliot R.

    2013-08-01

    Reactions of CO, C2H4, NO2, and O2 with neutral MnmOn clusters in a fast flow reactor are investigated both experimentally and theoretically. Single photon ionization at 118 nm is used to detect neutral cluster distributions through time of flight mass spectrometry. MnmOn clusters are generated through laser ablation of a manganese target in the presence of 5% O2/He carrier gas. A strong size dependent reactivity of MnmOn clusters is characterized. Reactions Mn2O5/Mn3O7 + CO → Mn2O4/Mn3O6 + CO2 are found for CO oxidation by MnmOn clusters, while only association products Mn2O3-5C2H4 and Mn3O5-7C2H4 are observed for reactions of C2H4 with small MnmOn clusters. Reactions of MnmOn clusters with NO2 and O2 are also investigated, and the small Mn2On clusters are easily oxidized by NO2. This activation suggests that a catalytic cycle can be generated for the Mn2O5 cluster: Mn2O5 + CO + NO2 → Mn2O4 + CO2 + NO2 → Mn2O5 + CO2 + NO. Density functional theory (DFT) calculations are performed to explore the potential energy surfaces for the reactions Mn2O4,5/Mn3O7 + CO → Mn2O3,4/Mn3O6 + CO2, Mn2O5 + C2H4 → Mn2O4 + CH3CHO, and Mn2O4 + NO2 → Mn2O5 + NO. Barrierless and thermodynamically favorable pathways are obtained for Mn2O5/Mn3O7 + CO and Mn2O4 + NO2 reactions. A catalytic cycle for CO oxidation by NO2 over a manganese oxide surface is proposed based on our experimental and theoretical investigations. The various atom related reaction mechanisms explored by DFT are in good agreement with the experimental results. Condensed phase manganese oxide is suggested to be a good catalyst for low temperature CO oxidation by NO2, especially for an oxygen rich sample.

  15. [Function and disease in manganese].

    PubMed

    Kimura, Mieko

    2016-07-01

    Manganese is a metal that has been known named a Greek word "Magnesia" meaning magnesia nigra from Roman Empire. Manganese provide the wide range of metablic function and the multiple abnomalities from its deficiency or toxicity. In 1931, the essentiality of manganese was demonstrated with the authoritative poor growth and declined reproduction in its deficiency. Manganese deficiency has been recognized in a number of species and its signs are impaired growth, impaired reproduction, ataxia, skeletal abnormalities and disorders in lipid and carbohydrate metabolism. Manganese toxicity is also acknowledged as health hazard for animals and humans. Here manganese nutrition, metabolism and metabolic function are summarized. PMID:27455810

  16. Globally sustainable manganese metal production and use.

    PubMed

    Hagelstein, Karen

    2009-09-01

    The "cradle to grave" concept of managing chemicals and wastes has been a descriptive analogy of proper environmental stewardship since the 1970s. The concept incorporates environmentally sustainable product choices-such as metal alloys utilized steel products which civilization is dependent upon. Manganese consumption is related to the increasing production of raw steel and upgrading ferroalloys. Nonferrous applications of manganese include production of dry-cell batteries, plant fertilizer components, animal feed and colorant for bricks. The manganese ore (high grade 35% manganese) production world wide is about 6 million ton/year and electrolytic manganese metal demand is about 0.7 million ton/year. The total manganese demand is consumed globally by industries including construction (23%), machinery (14%), and transportation (11%). Manganese is recycled within scrap of iron and steel, a small amount is recycled within aluminum used beverage cans. Recycling rate is 37% and efficiency is estimated as 53% [Roskill Metals and Minerals Reports, January 13, 2005. Manganese Report: rapid rise in output caused by Chinese crude steel production. Available from: http://www.roskill.com/reports/manganese.]. Environmentally sustainable management choices include identifying raw material chemistry, utilizing clean production processes, minimizing waste generation, recycling materials, controlling occupational exposures, and collecting representative environmental data. This paper will discuss two electrolytically produced manganese metals, the metal production differences, and environmental impacts cited to date. The two electrolytic manganese processes differ due to the addition of sulfur dioxide or selenium dioxide. Adverse environmental impacts due to use of selenium dioxide methodology include increased water consumption and order of magnitude greater solid waste generation per ton of metal processed. The use of high grade manganese ores in the electrolytic process also

  17. Manganese As a Metal Accumulator

    EPA Science Inventory

    Manganese deposits in water distribution systems accumulate metals, radionuclides and oxyanions by a combination of surface complexation, adsorption and solid substitution, as well as a combination of oxidation followed by manganese reduction and sorption of the oxidized constitu...

  18. Manganese biomining: A review.

    PubMed

    Das, A P; Sukla, L B; Pradhan, N; Nayak, S

    2011-08-01

    Biomining comprises of processing and extraction of metal from their ores and concentrates using microbial techniques. Currently this is used by the mining industry to extract copper, uranium and gold from low grade ores but not for low grade manganese ore in industrial scale. The study of microbial genomes, metabolites and regulatory pathways provide novel insights to the metabolism of bioleaching microorganisms and their synergistic action during bioleaching operations. This will promote understanding of the universal regulatory responses that the biomining microbial community uses to adapt to their changing environment leading to high metal recovery. Possibility exists of findings ways to imitate the entire process during industrial manganese biomining endeavor. This paper reviews the current status of manganese biomining research operations around the world, identifies factors that drive the selection of biomining as a processing technology, describes challenges in exploiting these innovations, and concludes with a discussion of Mn biomining's future. PMID:21632238

  19. Conserved histidine of metal transporter AtNRAMP1 is crucial for optimal plant growth under manganese deficiency at chilling temperatures.

    PubMed

    Ihnatowicz, Anna; Siwinska, Joanna; Meharg, Andrew A; Carey, Manus; Koornneef, Maarten; Reymond, Matthieu

    2014-06-01

    Manganese (Mn) is an essential nutrient required for plant growth, in particular in the process of photosynthesis. Plant performance is influenced by various environmental stresses including contrasting temperatures, light or nutrient deficiencies. The molecular responses of plants exposed to such stress factors in combination are largely unknown. Screening of 108 Arabidopsis thaliana (Arabidopsis) accessions for reduced photosynthetic performance at chilling temperatures was performed and one accession (Hog) was isolated. Using genetic and molecular approaches, the molecular basis of this particular response to temperature (G × E interaction) was identified. Hog showed an induction of a severe leaf chlorosis and impaired growth after transfer to lower temperatures. We demonstrated that this response was dependent on the nutrient content of the soil. Genetic mapping and complementation identified NRAMP1 as the causal gene. Chlorotic phenotype was associated with a histidine to tyrosine (H239Y) substitution in the allele of Hog NRAMP1. This led to lethality when Hog seedlings were directly grown at 4°C. Chemical complementation and hydroponic culture experiments showed that Mn deficiency was the major cause of this G × E interaction. For the first time, the NRAMP-specific highly conserved histidine was shown to be crucial for plant performance. PMID:24571269

  20. Suppressing Manganese Dissolution from Lithium Manganese Oxide Spinel Cathodes with Single-Layer Graphene

    SciTech Connect

    Jaber-Ansari, Laila; Puntambekar, Kanan P.; Kim, Soo; Aykol, Muratahan; Luo, Langli; Wu, Jinsong; Myers, Benjamin D.; Iddir, Hakim; Russell, John T.; Saldana, Spencer J.; Kumar, Rajan; Thackeray, Michael M.; Curtiss, Larry A.; Dravid, Vinayak P.; Wolverton, Christopher M.; Hersam, Mark C.

    2015-06-24

    Spinel-structured LiMn 2 O 4 (LMO) is a desirable cathode material for Li-ion batteries due to its low cost, abundance, and high power capability. However, LMO suffers from limited cycle life that is triggered by manganese dissolution into the electrolyte during electrochemical cycling. Here, it is shown that single-layer graphene coatings suppress manganese dissolution, thus enhancing the performance and lifetime of LMO cathodes. Relative to lithium cells with uncoated LMO cathodes, cells with graphene-coated LMO cathodes provide improved capacity retention with enhanced cycling stability. X-ray photoelectron spectroscopy reveals that graphene coatings inhibit manganese depletion from the LMO surface. Additionally, transmission electron microscopy demonstrates that a stable solid electrolyte interphase is formed on graphene, which screens the LMO from direct contact with the electrolyte. Density functional theory calculations provide two mechanisms for the role of graphene in the suppression of manganese dissolution. First, common defects in single-layer graphene are found to allow the transport of lithium while concurrently acting as barriers for manganese diffusion. Second, graphene can chemically interact with Mn 3+ at the LMO electrode surface, promoting an oxidation state change to Mn 4+ , which suppresses dissolution.

  1. Health assessment document for manganese. Final report

    SciTech Connect

    Bilinski, H.; Bruins, R.J.F.; Erdreich, L.; Fugas, M.; Kello, D.

    1984-08-01

    The document evaluates data on occurrence, sources, and transport of manganese in the environment and data on metabolism, pharmacokinetics, laboratory toxicological and epidemiologic studies to determine the nature and dose response relationship of potential health effects on humans. Nationwide air sampling data indicate that mean manganese concentrations have declined from 0.11 micrograms per cu. m. in 1953-1957 to 0.033 micrograms per cu. m. in 1982. The effects of major concern to humans exposed to manganese are on neurological and on pulmonary function. The CNS effects have been observed in humans at exposure levels above 5 mg/cu. m. and are incapacitating and generally irreversible. Data are equivocal between 1 and 5 mg/cu. m. but suggest decreased prevalence. There are no reports of these effects below 0.3 mg/cu. m. exposure. Pneumonia and chronic bronchitis occur at levels which are associated with neurological effects. Reduced lung function has been reported in children exposed to an estimated 3-11 micrograms per cu. m. from emission of a ferromanganese plant. However, studies of workers exposed to 40 micrograms per cu. m. did not show respiratory symptoms. Animal studies qualitatively support pulmonary effects of manganese exposure. Respiratory symptoms occur at lower levels than neurological symptoms and are therefore considered to be the critical effect based on available data.

  2. Manganese, Metallogenium, and Martian Microfossils

    NASA Technical Reports Server (NTRS)

    Stein, L. Y.; Nealson, K. H.

    1999-01-01

    Manganese could easily be considered an abundant element in the Martian regolith, assuming that the composition of martian meteorites reflects the composition of the planet. Mineralogical analyses of 5 SNC meteorites have revealed an average manganese oxide concentration of 0.48%, relative to the 0.1% concentration of manganese found in the Earth's crust. On the Earth, the accumulation of manganese oxides in oceans, soils, rocks, sedimentary ores, fresh water systems, and hydrothermal vents can be largely attributed to microbial activity. Manganese is also a required trace nutrient for most life forms and participates in many critical enzymatic reactions such as photosynthesis. The wide-spread process of bacterial manganese cycling on Earth suggests that manganese is an important element to both geology and biology. Furthermore, there is evidence that bacteria can be fossilized within manganese ores, implying that manganese beds may be good repositories for preserved biomarkers. A particular genus of bacteria, known historically as Metallogenium, can form star-shaped manganese oxide minerals (called metallogenium) through the action of manganese oxide precipitation along its surface. Fossilized structures that resemble metallogenium have been found in Precambrian sedimentary formations and in Cretaceous-Paleogene cherts. The Cretaceous-Paleogene formations are highly enriched in manganese and have concentrations of trace elements (Fe, Zn, Cu, and Co) similar to modern-day manganese oxide deposits in marine environments. The appearance of metallogenium-like fossils associated with manganese deposits suggests that bacteria may be preserved within the minerals that they form. Additional information is contained in the original extended abstract.

  3. Manganese reduction by microbes from oxic regions of the Lake Vanda (Antarctica) water column

    SciTech Connect

    Bratina, B.J.; Stevenson, B.S.; Schmidt, T.M.; Green, W.J.

    1998-10-01

    Depth profiles of metals in Lake Vanda, a permanently ice-covered, stratified Antarctic lake, suggest the importance of particulate manganese oxides in the scavenging, transport, and release of metals. Since manganese oxides can be solubilized by manganese-reducing bacteria, microbially mediated manganese reduction was investigated in Lake Vanda. Microbes concentrated from oxic regions of the water column, encompassing a peak of soluble manganese [Mn(II)], reduced synthetic manganese oxides (MnO{sub 2}) when incubated aerobically, Pure cultures of manganese-reducing bacteria were readily isolated from waters collected near the oxic Mn(II) peak. Based on phylogenetic analysis of the 16S rRNA gene sequence, most of the isolated manganese reducers belong to the genus Carnobacterium. Cultures of a phylogenetically representative strain of Carnobacterium reduced synthetic MnO{sub 2} in the presence of sodium azide, as was seen in field assays. Unlike anaerobes that utilize manganese oxides as terminal electron acceptors in respiration, isolates of the genus Carnobacterium reduced Mn(IV) via a diffusible compound under oxic conditions. The release of adsorbed trace metals accompanying the solubilization of manganese oxides may provide populations of Carnobacterium with a source of nutrients in this extremely oligotrophic environment.

  4. Manganese Reduction by Microbes from Oxic Regions of the Lake Vanda (Antarctica) Water Column

    PubMed Central

    Bratina, Bonnie Jo; Stevenson, Bradley S.; Green, William J.; Schmidt, Thomas M.

    1998-01-01

    Depth profiles of metals in Lake Vanda, a permanently ice-covered, stratified Antarctic lake, suggest the importance of particulate manganese oxides in the scavenging, transport, and release of metals. Since manganese oxides can be solubilized by manganese-reducing bacteria, microbially mediated manganese reduction was investigated in Lake Vanda. Microbes concentrated from oxic regions of the water column, encompassing a peak of soluble manganese [Mn(II)], reduced synthetic manganese oxides (MnO2) when incubated aerobically. Pure cultures of manganese-reducing bacteria were readily isolated from waters collected near the oxic Mn(II) peak. Based on phylogenetic analysis of the 16S rRNA gene sequence, most of the isolated manganese reducers belong to the genus Carnobacterium. Cultures of a phylogenetically representative strain of Carnobacterium reduced synthetic MnO2 in the presence of sodium azide, as was seen in field assays. Unlike anaerobes that utilize manganese oxides as terminal electron acceptors in respiration, isolates of the genus Carnobacterium reduced Mn(IV) via a diffusible compound under oxic conditions. The release of adsorbed trace metals accompanying the solubilization of manganese oxides may provide populations of Carnobacterium with a source of nutrients in this extremely oligotrophic environment. PMID:9758801

  5. Differential Regulation of Iron- and Manganese-Specific MtsABC and Heme-Specific HtsABC Transporters by the Metalloregulator MtsR of Group A Streptococcus

    PubMed Central

    Hanks, Tracey S.; Liu, Mengyao; McClure, Michael J.; Fukumura, Maki; Duffy, Angela; Lei, Benfang

    2006-01-01

    The genome of the human pathogen group A Streptococcus (GAS) encodes the transporters MtsABC, FtsABCD, and HtsABC to take up ferric and manganese ions, ferric ferrichrome, and heme, respectively. The GAS genome also encodes two metalloregulators PerR and MtsR. To understand the regulation of the expression of these transporters, the mtsR and perR deletion mutants of a GAS serotype M1 strain were generated, and the effects of the deletions and Fe3+, Mn2+, and Zn2+ on the expression of mtsA, htsA, and ftsB were examined. Mn2+ dramatically depresses mtsA transcription and levels of the MtsA protein but does not downregulate the expression of htsA and ftsB. Fe3+ decreases the expression of mtsA and htsA but has no effect on ftsB expression. Zn2+ has no effect on the expression of all three genes. The deletion of mtsR abolishes the Mn2+- and Fe3+-induced depression of mtsA expression and the Fe3+-dependent decrease in htsA expression. The deletion of mtsR does not significantly alter GAS virulence in a mouse model of subcutaneous infection. The deletion of perR does not affect the expression of the genes in response to the metal ions. MtsR binds to the mts promoter region in the presence of Mn2+ or Fe2+. The results indicate that MtsR differentially regulates the expression of mtsABC and htsABC. PMID:16926405

  6. Nonoccupational environmental exposure to manganese is linked to deficits in peripheral and central olfactory function.

    PubMed

    Guarneros, Marco; Ortiz-Romo, Nahum; Alcaraz-Zubeldia, Mireya; Drucker-Colín, René; Hudson, Robyn

    2013-11-01

    Manganese is of growing concern as a toxic air pollutant. It is readily transported from the olfactory epithelium to the olfactory bulb, and unlike other metals, it is transported transynaptically to structures deep within the brain. However, little is known regarding the possible effect of nonoccupational exposure to manganese on olfactory function. Using the Sniffin' Sticks test battery, we compared the olfactory performance of subjects from a manganese mining district living <1 km from a manganese processing plant, with nonexposed subjects living 50 km from the closest source of exposure (N = 30/group). Groups were matched for age, sex, and schooling, and none had ever worked in mining-related activities. Concentrations of manganese in hair were measured as a biomarker of exposure; exposed subjects had significantly higher concentrations than nonexposed subjects. They were also significantly outperformed by the nonexposed subjects on all olfactory measures (threshold, discrimination, and identification), indicating adverse effects of manganese exposure on a range of olfactory functions, including those involving higher order cognitive processes. This contrasts with previous findings showing adverse peripheral but not central effects on olfactory function of big city air pollution, which mostly consists of toxicants known to affect the olfactory epithelium but with lower transynaptic transport capacity compared with manganese. We conclude that nonoccupational exposure to airborne manganese is associated with decrements in both peripheral and central olfactory function. PMID:24097266

  7. Tensile Strain Effects on the Magneto-transport in Calcium Manganese Oxide Thin Films: Comparison with its Hole-doped Counterpart

    NASA Astrophysics Data System (ADS)

    Lawson, Bridget; Neubauer, Samuel; Chaudhry, Adeel; Hart, Cacie; Ferrone, Natalie; Houston, David; Yong, Grace; Kolagani, Rajeswari

    Magnetoresistance properties of the epitaxial thin films of doped rare earth manganites are known to be influenced by the effect of bi-axial strain induced by lattice mismatch with the substrate. In hole-doped manganites, the effect of both compressive and tensile strain is qualitatively consistent with the expected changes in unit cell symmetry from cubic to tetragonal, leading to Jahn-Teller strain fields that affect the energy levels of Mn3 + energy levels. Recent work in our laboratory on CaMnO3 thin films has pointed out that tetragonal distortions introduced by tensile lattice mismatch strain may also have the effect of modulating the oxygen content of the films in agreement with theoretical models that propose such coupling between strain and oxygen content. Our research focuses on comparing the magneto-transport properties of hole-doped manganite LaCaMnO3 thin films with that of its electron doped counter parts, in an effort to delineate the effects of oxygen stoichiometry changes on magneto-transport from the effects of Jahn-Teller type strain. Towson University Office of Undergraduate Research, Fisher Endowment Grant and Undergraduate Research Grant from the Fisher College of Science and Mathematics, Seed Funding Grant from the School of Emerging technologies and the NSF Grant ECCS 112856.

  8. PROGRESS REPORT. TRANSURANIC INTERFACIAL REACTION STUDIES ON MANGANESE OXIDE HYDROXIDE MINERAL SURFACES

    EPA Science Inventory

    Several DOE sites have been contaminated by transuranic radionuclide (TRU) discharges including neptunium and plutonium. Their interaction with the surrounding geological media can affect the transport and remediation of these radionuclides in the environment. Manganese based min...

  9. MANGANESE TOXICOKINETICS AT THE BLOOD-BRAIN BARRIER

    EPA Science Inventory

    Investigators expect to study the mechanisms by which manganese enters and leaves the brain across the blood–brain barrier and, in particular, whether transporter molecules are involved. The investigators plan to use in vivo brain perfusion in rats as well as in vitro...

  10. Effects of developmental exposure to manganese and/or low iron diet: Changes to metal transporters, sucrose preference, elevated zero-maze, open-field, and locomotion in response to fenfluramine, amphetamine, and MK-801

    PubMed Central

    Amos-Kroohs, Robyn M.; Bloor, Colin P.; Qureshi, Momina A.; Vorhees, Charles V.; Williams, Michael T.

    2015-01-01

    Manganese overexposure (MnOE) can be neurotoxic. In humans this can occur through occupational exposure, air or water contamination, well water, soy milk, and some baby formulas. In children MnOE has been associated with cognitive and behavioral deficits. The effects of MnOE may be modified by factors such as iron status. We hypothesized that developmental MnOE would be exacerbated by iron deficiency. A diet with a 90% decrease in iron (FeD) was given to gravid female rats starting on embryonic day 15 and continued through postnatal day (P)28. Mn (100 mg/kg) or vehicle (VEH) was administered by gavage every other day from P4–28. Metal transporters and receptors (divalent metal transporter-1 (DMT1), transferrin (Tf), transferrin receptor (TfR), and zip8 (zrt8)) were quantified in brain at P28. These markers were increased but the changes were specific: MnOE increased TfR and decreased Tf in hippocampus, whereas FeD increased TfR in neostriatum and increased TfR and DMT1 in the hippocampus, and the combination increased TfR in neostriatum (zip8 was unaffected). Identically treated animals were tested behaviorally at P29 or P60. The combination of FeD+MnOE increased head dips in an elevated zero-maze, reversed deficits in sucrose preference induced by MnOE alone, and increased spontaneous locomotion in an open-field. Rats were also evaluated for changes in locomotor activity after challenge with (±)-fenfluramine (FEN, a 5-HT agonist: 5 mg/kg), MK-801 (MK801, an NMDA antagonist: 0.2 mg/kg), or (+)amphetamine (AMPH, a dopamine agonist: 1 mg/kg). Compared with VEH animals, MnOE animals were more hyperactive after fenfluramine, amphetamine, or MK-801, regardless of FeD exposure. The results indicate persistent effects of developmental MnOE on brain and behavior but few interactions with dietary iron deficiency. PMID:26295019

  11. The anomalous Hall effect and related transport phenomena in ferromagnetic spinel copper chromium selenium bromide, manganese-doped chalcopyrite copper gallium ditelluride, and ruthenate bismuth ruthenate

    NASA Astrophysics Data System (ADS)

    Lee, Wei-Li

    One of the interesting and unsettled transport phenomena is the, so called, "anomalous Hall Effect". It generally refers to the phenomenon of a non-linear field dependence of the Hall resistivity rhoxy. An emerging idea relates to the "gauge field O" experienced by electrons. It gives rise to Berry phase accumulation. In ferromagnets, a non-vanishing O( k⃗ ) is related to the spin-orbit coupling and the time-reversal asymmetry. We show that, in the ferromagnetic spinel CuCr2Se 4-xBrx, the anomalous Hall conductivity sigma xy (normalized to per carrier, at 5K) remains unchanged with a 1000-fold increase in resistivity. From the anomalous Nernst effect, we uncover a simple relation for the off-diagonal Peltier conductivity tensor alphaxy, which is a measure of a transverse electrical current density generated per unit of applied temperature gradient. They both strongly support the anomalous-velocity theory based on the intrinsic spin-orbit coupling of the electrons. An alternative way to procure O is from the spin-chirality effect. In the Mn-doped chalcopyrite semiconductor CuGaTe2, with a few percent doping, the orbitals of the Mn ions overlap to form an impurity band. Therefore, the electrons will accumulate Berry phase while hopping around the Mn ions that have a non-collinear magnetic ground state. We observed the enhanced and non-monotonic field dependence of rhoxy, which may be understood from the spin-chirality effect. Finally, we studied the Hall effect and thermopower in the ruthenate Bi3Ru3O 11. From the Hall effect, we observed field-tuning of electron and hole populations. We also found a large field dependence of the thermopower at low temperature. The origin of the colossal field-dependence in the thermopower is still an open question, but it is linked to the unusual electronic properties in the Bi3Ru3O11.

  12. Homeostatic control of manganese excretion in the neonatal rat

    SciTech Connect

    Ballatori, N.; Miles, E.; Clarkson, T.W.

    1987-05-01

    Previous studies in neonatal and suckling animals showed that immature animals have a greatly diminished capacity to excrete manganese and therefore were considered to be unable to regulate tissue manganese concentrations. In contrast, the present studies indicate that suckling rats have the capacity to excrete excess manganese at rates nearly comparable to those of adults. Eight- to 10-day-old rats given a tracer dose of /sup 54/MnCl/sub 2/ (essentially carrier free), either via gavage or by intraperitoneal injection showed little elimination of the /sup 54/Mn until the 18-19th day of life, when there was an abrupt increase in the rate of the metal's excretion. However, when manganese was given in doses of 1 and 10 mg/kg, the young animals excreted from 30-70% of the dose in only 4 days, at which time a new rate of excretion was achieved. This enhanced rate of excretion remained constant until the 18-19th day of life, when it was again accelerated. Biliary excretion of manganese, the primary route for the elimination of the metal, was only 30-60% lower in 14-day-old rats compared with adults at doses ranging from tracer to 10 mg /sup 54/Mn/kg. For both the 14-day-old and adult rats, an apparent biliary transport maximum was reached at a dose of 10 mg Mn/kg. These studies indicate that the excretory pathways for manganese are well developed in the neonatal rat. The avid retention of tracer quantities of manganese by the neonate may be a consequence of the scarcity of this essential trace metal in its diet.

  13. Mineral of the month: manganese

    USGS Publications Warehouse

    Corathers, Lisa

    2005-01-01

    Manganese is one of the most important ferrous metals and one of the few for which the United States is totally dependent on imports. It is a black, brittle element predominantly used in metallurgical applications as an alloying addition, particularly in steel and cast iron production, which together provide the largest market for manganese (about 83 percent). It is also used as an alloy with nonferrous metals such as aluminum and copper. Nonmetallurgical applications of manganese include battery cathodes, soft ferrite magnets used in electronics, micronutrients found in fertilizers and animal feed, water treatment chemicals, and a colorant for bricks and ceramics.

  14. Np and Pu Sorption to Manganese Oxide Minerals

    SciTech Connect

    Zhao, P; Johnson, M R; Roberts, S K; Zavarin, M

    2005-08-30

    Manganese oxide minerals are a significant component of the fracture lining mineralogy at Yucca Mountain (Carlos et al., 1993) and within the tuff-confining unit at Yucca Flat (Prothro, 1998), Pahute Mesa (Drellack et al., 1997), and other locations at the Nevada Test Site (NTS). Radionuclide sorption to manganese oxide minerals was not included in recent Lawrence Livermore National Laboratory (LLNL) hydrologic source term (HST) models which attempt to predict the migration behavior of radionuclides away from underground nuclear tests. However, experiments performed for the Yucca Mountain Program suggest that these minerals may control much of the retardation of certain radionuclides, particularly Np and Pu (Triay et al., 1991; Duff et al., 1999). As a result, recent HST model results may significantly overpredict radionuclide transport away from underground nuclear tests. The sorption model used in HST calculations performed at LLNL includes sorption to iron oxide, calcite, zeolite, smectite, and mica minerals (Zavarin and Bruton 2004a; 2004b). For the majority of radiologic source term (RST) radionuclides, we believe that this accounts for the dominant sorption processes controlling transport. However, for the case of Np, sorption is rather weak to all but the iron and manganese oxides (Figure 1). Thus, we can expect to significantly reduce predicted Np transport by accounting for Np sorption to manganese oxides. Similarly, Pu has been shown to be predominantly associated with manganese oxides in Yucca Mountain fractured tuffs (Duff et al., 1999). Recent results on colloid-facilitated Pu transport (Kersting and Reimus, 2003) also suggest that manganese oxide coatings on fracture surfaces may compete with colloids for Pu, thus reducing the effects of colloid-facilitated Pu transport (Figure 1b). The available data suggest that it is important to incorporate Np and Pu sorption to manganese oxides in reactive transport models. However, few data are available for

  15. Effects of manganese-excess on CO2 assimilation, ribulose-1,5-bisphosphate carboxylase/oxygenase, carbohydrates and photosynthetic electron transport of leaves, and antioxidant systems of leaves and roots in Citrus grandis seedlings

    PubMed Central

    2010-01-01

    Background Very little is known about the effects of manganese (Mn)-excess on citrus photosynthesis and antioxidant systems. Seedlings of sour pummelo (Citrus grandis) were irrigated for 17 weeks with nutrient solution containing 2 μM (control) or 500 μM (excess) MnSO4. The objective of this study were to understand the mechanisms by which Mn-excess leads to a decrease in CO2 assimilation and to test the hypothesis that Mn-induced changes in antioxidant systems differ between roots and leaves. Results Mn-excess decreased CO2 assimilation and stomatal conductance, increased intercellular CO2 concentration, but did not affect chlorophyll (Chl) level. Both initial and total ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) activity in Mn-excess leaves decreased to a lesser extent than CO2 assimilation. Contents of glucose, fructose, starch and total nonstructural carbohydrates did not differ between Mn-excess leaves and controls, while sucrose content was higher in the former. Chl a fluorescence (OJIP) transients from Mn-excess leaves showed increased O-step and decreased P-step, accompanied by positive L- and K-bands. Mn-excess decreased maximum quantum yield of primary photochemistry (Fv/Fm) and total performance index (PItot,abs), but increased relative variable fluorescence at I-steps (VI) and energy dissipation. On a protein basis, Mn-excess leaves displayed higher activities of monodehydroascorbate reductase (MDAR), glutathione reductase (GR), superoxide dismutase (SOD), catalase (CAT) and guaiacol peroxidase (GPX) and contents of antioxidants, similar ascorbate peroxidase (APX) activities and lower dehydroascorbate reductase (DHAR) activities; while Mn-excess roots had similar or lower activities of antioxidant enzymes and contents of antioxidants. Mn-excess did not affect malondialdehyde (MDA) content of roots and leaves. Conclusions Mn-excess impaired the whole photosynthetic electron transport chain from the donor side of photosystem II (PSII) up

  16. Manganese oxidation model for rivers

    USGS Publications Warehouse

    Hess, Glen W.; Kim, Byung R.; Roberts, Philip J.W.

    1989-01-01

    The presence of manganese in natural waters (>0.05 mg/L) degrades water-supply quality. A model was devised to predict the variation of manganese concentrations in river water released from an impoundment with the distance downstream. The model is one-dimensional and was calibrated using dissolved oxygen, biochemical oxygen demand, pH, manganese, and hydraulic data collected in the Duck River, Tennessee. The results indicated that the model can predict manganese levels under various conditions. The model was then applied to the Chattahoochee River, Georgia. Discrepancies between observed and predicted may be due to inadequate pH data, precipitation of sediment particles, unsteady flow conditions in the Chattahoochee River, inaccurate rate expressions for the low pH conditions, or their combinations.

  17. Manganese-Enhanced Magnetic Resonance Imaging (MEMRI)

    PubMed Central

    Massaad, Cynthia A.; Pautler, Robia G.

    2012-01-01

    The use of manganese ions (Mn2+) as an MRI contrast agent was introduced over 20 years ago in studies of Mn2+ toxicity in anesthetized rats (1). Manganese-enhanced MRI (MEMRI) evolved in the late nineties when Koretsky and associates pioneered the use of MEMRI for brain activity measurements (2) as well as neuronal tract tracing (3). Currently, MEMRI has three primary applications in biological systems: (1) contrast enhancement for anatomical detail, (2) activity-dependent assessment and (3) tracing of neuronal connections or tract tracing. MEMRI relies upon the following three main properties of Mn2+: (1) it is a paramagnetic ion that shortens the spin lattice relaxation time constant (T1) of tissues, where it accumulates and hence functions as an excellent T1 contrast agent; (2) it is a calcium (Ca2+) analog that can enter excitable cells, such as neurons and cardiac cells via voltage-gated Ca2+ channels; and (3) once in the cells Mn2+ can be transported along axons by microtubule-dependent axonal transport and can also cross synapses trans-synaptically to neighboring neurons. This chapter will emphasize the methodological approaches towards the use of MEMRI in biological systems. PMID:21279601

  18. Uniform manganese hexacyanoferrate hydrate nanocubes featuring superior performance for low-cost supercapacitors and nonenzymatic electrochemical sensors.

    PubMed

    Pang, Huan; Zhang, Yizhou; Cheng, Tao; Lai, Wen-Yong; Huang, Wei

    2015-10-14

    Uniform manganese hexacyanoferrate hydrate nanocubes are prepared via a simple chemical precipitation method at room temperature. Due to both micro/mesopores of the Prussian blue analogue and nanocubic structures, the manganese hexacyanoferrate hydrate nanocubes allow the efficient charge transfer and mass transport for electrolyte solution and chemical species. Thus, the manganese hexacyanoferrate hydrate nanocube electrode shows a good rate capability and cycling stability for electrochemical capacitors. Furthermore, electrodes modified with manganese hexacyanoferrate hydrate nanocubes demonstrate a sensitive electrochemical response to hydrogen peroxide (H2O2) in buffer solutions with a high selectivity. PMID:26370568

  19. Manganese Homeostasis in the Nervous System

    PubMed Central

    Chen, Pan; Chakraborty, Sudipta; Mukhopadhyay, Somshuvra; Lee, Eunsook; Paoliello, Monica MB; Bowman, Aaron B; Aschner, Michael

    2015-01-01

    Manganese (Mn) is an essential heavy metal that is naturally found in the environment. Daily intake through dietary sources provides the necessary amount required for several key physiological processes, including antioxidant defense, energy metabolism, immune function and others. However, overexposure from environmental sources can result in a condition known as manganism that features symptomatology similar to Parkinson's disease (PD). This disorder presents with debilitating motor and cognitive deficits that arise from a neurodegenerative process. In order to maintain a balance between its essentiality and neurotoxicity, several mechanisms exist to properly buffer cellular Mn levels. These include transporters involved in Mn uptake, and newly discovered Mn efflux mechanisms. This review will focus on current studies related to mechanisms underlying Mn import and export, primarily the Mn transporters, and their function and roles in Mn-induced neurotoxicity. PMID:25982296

  20. Manganese cycles and the origin of manganese nodules, Oneida Lake, New York, U.S.A.

    USGS Publications Warehouse

    Dean, W.E.; Moore, W.S.; Nealson, K.H.

    1981-01-01

    Oneida Lake is a large shallow lake in central New York that is characterized by high algal productivity and concentrated deposits of freshwater manganese nodules. Budgets for Mn in the lake and its tributaries show a net loss of 23 metric tons of manganese within the lake per year with ???95% deposited in manganese nodules and the rest incorporated in the sediments. Erosion of nodules in the shallow well-oxygenated central part of the lake produces fragments of nodules as well as Mn-coated sand grains that are transported to adjacent deeper, more reducing parts of the lake where they sink into the anoxic sediments and MnO2 is reduced to Mn2+. This produces a high concentration of Mn2+ in the pore waters of these sediments and Mn2+ diffuses back into the water column. Growth of manganese nodules in Oneida Lake is characterized by periods of rapid accretion (> 1 mm 100 yr.) alternating with periods of no-growth or erosion. Rapid growth of nodules may be aided by the stripping of Mn from the water column by algae and bacteria. In addition, the high algal productivity of Oneida Lake produces a high-pH high-oxygen environment during the summer months that is maintained throughout the water column in the central part of the lake by almost continuous wind mixing. Thus, the cycle of Mn within the lake involves an interaction of the weather, the biota, the sediments, the nodules, and Mn dissolved in the lake and interstitial waters. ?? 1981.

  1. Bog Manganese Ore: A Resource for High Manganese Steel Making

    NASA Astrophysics Data System (ADS)

    Pani, Swatirupa; Singh, Saroj K.; Mohapatra, Birendra K.

    2016-06-01

    Bog manganese ore, associated with the banded iron formation of the Iron Ore Group (IOG), occurs in large volume in northern Odisha, India. The ore is powdery, fine-grained and soft in nature with varying specific gravity (2.8-3.9 g/cm3) and high thermo-gravimetric loss, It consists of manganese (δ-MnO2, manganite, cryptomelane/romanechite with minor pyrolusite) and iron (goethite/limonite and hematite) minerals with sub-ordinate kaolinite and quartz. It shows oolitic/pisolitic to globular morphology nucleating small detritus of quartz, pyrolusite/romanechite and hematite. The ore contains around 23% Mn and 28% Fe with around 7% of combined alumina and silica. Such Mn ore has not found any use because of its sub-grade nature and high iron content, and is hence considered as waste. The ore does not respond to any physical beneficiation techniques because of the combined state of the manganese and iron phases. Attempts have been made to recover manganese and iron value from such ore through smelting. A sample along with an appropriate charge mix when processed through a plasma reactor, produced high-manganese steel alloy having 25% Mn within a very short time (<10 min). Minor Mn content from the slag was recovered through acid leaching. The aim of this study has been to recover a value-added product from the waste.

  2. Extraction of manganese from electrolytic manganese residue by bioleaching.

    PubMed

    Xin, Baoping; Chen, Bing; Duan, Ning; Zhou, Changbo

    2011-01-01

    Extraction of manganese from electrolytic manganese residues using bioleaching was investigated in this paper. The maximum extraction efficiency of Mn was 93% by sulfur-oxidizing bacteria at 4.0 g/l sulfur after bioleaching of 9days, while the maximum extraction efficiency of Mn was 81% by pyrite-leaching bacteria at 4.0 g/l pyrite. The series bioleaching first by sulfur-oxidizing bacteria and followed by pyrite-leaching bacteria evidently promoted the extraction of manganese, witnessing the maximum extraction efficiency of 98.1%. In the case of sulfur-oxidizing bacteria, the strong dissolution of bio-generated sulfuric acid resulted in extraction of soluble Mn2+, while both the Fe2+ catalyzed reduction of Mn4+ and weak acidic dissolution of Mn2+ accounted for the extraction of manganese with pyrite-leaching bacteria. The chemical simulation of bioleaching process further confirmed that the acid dissolution of Mn2+ and Fe2+ catalyzed reduction of Mn4+ were the bioleaching mechanisms involved for Mn extraction from electrolytic manganese residues. PMID:21050747

  3. Bog Manganese Ore: A Resource for High Manganese Steel Making

    NASA Astrophysics Data System (ADS)

    Pani, Swatirupa; Singh, Saroj K.; Mohapatra, Birendra K.

    2016-05-01

    Bog manganese ore, associated with the banded iron formation of the Iron Ore Group (IOG), occurs in large volume in northern Odisha, India. The ore is powdery, fine-grained and soft in nature with varying specific gravity (2.8-3.9 g/cm3) and high thermo-gravimetric loss, It consists of manganese (δ-MnO2, manganite, cryptomelane/romanechite with minor pyrolusite) and iron (goethite/limonite and hematite) minerals with sub-ordinate kaolinite and quartz. It shows oolitic/pisolitic to globular morphology nucleating small detritus of quartz, pyrolusite/romanechite and hematite. The ore contains around 23% Mn and 28% Fe with around 7% of combined alumina and silica. Such Mn ore has not found any use because of its sub-grade nature and high iron content, and is hence considered as waste. The ore does not respond to any physical beneficiation techniques because of the combined state of the manganese and iron phases. Attempts have been made to recover manganese and iron value from such ore through smelting. A sample along with an appropriate charge mix when processed through a plasma reactor, produced high-manganese steel alloy having 25% Mn within a very short time (<10 min). Minor Mn content from the slag was recovered through acid leaching. The aim of this study has been to recover a value-added product from the waste.

  4. 21 CFR 582.5446 - Manganese chloride.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5446 Manganese chloride. (a) Product. Manganese chloride. (b) Conditions of use....

  5. 21 CFR 582.5461 - Manganese sulfate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5461 Manganese sulfate. (a) Product. Manganese sulfate. (b) Conditions of use....

  6. 21 CFR 582.5452 - Manganese gluconate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5452 Manganese gluconate. (a) Product. Manganese gluconate. (b) Conditions of use....

  7. 21 CFR 582.5461 - Manganese sulfate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5461 Manganese sulfate. (a) Product. Manganese sulfate. (b) Conditions of use....

  8. 21 CFR 582.5458 - Manganese hypophosphite.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5458 Manganese hypophosphite. (a) Product. Manganese hypophosphite. (b) Conditions of...

  9. 21 CFR 582.5449 - Manganese citrate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5449 Manganese citrate. (a) Product. Manganese citrate. (b) Conditions of use....

  10. 21 CFR 582.5449 - Manganese citrate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5449 Manganese citrate. (a) Product. Manganese citrate. (b) Conditions of use....

  11. 21 CFR 582.5458 - Manganese hypophosphite.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5458 Manganese hypophosphite. (a) Product. Manganese hypophosphite. (b) Conditions of...

  12. 21 CFR 582.5452 - Manganese gluconate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5452 Manganese gluconate. (a) Product. Manganese gluconate. (b) Conditions of use....

  13. Controlled Synthesis of Hollow Manganese Oxide Nanocrystals.

    PubMed

    Nam, Ki Min; Oh, Kyung Hee; Ham, Kyung-Sik

    2016-02-01

    Carbon spheres have been prepared from glucose under hydrothermal conditions to facilitate the synthesis of hollow manganese oxides. The phases of manganese oxide are controlled by changing annealing temperature of the manganese monoxide on a carbon sphere template. The particles on the carbon surface get an agglomeration and make dense oxide shell during the calcination step, which result in typical hollow structures. The electrochemical properties of hollow manganese oxides have been investigated to elucidate their relative catalytic activities. PMID:27433689

  14. Manganese depresses rat heart muscle respiration

    Technology Transfer Automated Retrieval System (TEKTRAN)

    It has previously been reported that moderately high dietary manganese (Mn) in combination with marginal magnesium (Mg) resulted in ultrastructural damage to heart mitochondria. Manganese may replace Mg in biological functions, including the role of enzyme cofactor. Manganese may accumulate and subs...

  15. SEPARATING PROTOACTINIUM WITH MANGANESE DIOXIDE

    DOEpatents

    Seaborg, G.T.; Gofman, J.W.; Stoughton, R.W.

    1958-04-22

    The preparation of U/sup 235/ and an improved method for isolating Pa/ sup 233/ from foreign products present in neutronirradiated thorium is described. The method comprises forming a solution of neutron-irradiated thorium together with a manganous salt, then adding potassium permanganate to precipitate the manganese as manganese dioxide whereby protoactinium is carried down with the nnanganese dioxide dissolving the precipitate, adding a soluble zirconium salt, and adding phosphate ion to precipitate zirconium phosphate whereby protoactinium is then carried down with the zirconium phosphate to effect a further concentration.

  16. Uniform manganese hexacyanoferrate hydrate nanocubes featuring superior performance for low-cost supercapacitors and nonenzymatic electrochemical sensors

    NASA Astrophysics Data System (ADS)

    Pang, Huan; Zhang, Yizhou; Cheng, Tao; Lai, Wen-Yong; Huang, Wei

    2015-09-01

    Uniform manganese hexacyanoferrate hydrate nanocubes are prepared via a simple chemical precipitation method at room temperature. Due to both micro/mesopores of the Prussian blue analogue and nanocubic structures, the manganese hexacyanoferrate hydrate nanocubes allow the efficient charge transfer and mass transport for electrolyte solution and chemical species. Thus, the manganese hexacyanoferrate hydrate nanocube electrode shows a good rate capability and cycling stability for electrochemical capacitors. Furthermore, electrodes modified with manganese hexacyanoferrate hydrate nanocubes demonstrate a sensitive electrochemical response to hydrogen peroxide (H2O2) in buffer solutions with a high selectivity.Uniform manganese hexacyanoferrate hydrate nanocubes are prepared via a simple chemical precipitation method at room temperature. Due to both micro/mesopores of the Prussian blue analogue and nanocubic structures, the manganese hexacyanoferrate hydrate nanocubes allow the efficient charge transfer and mass transport for electrolyte solution and chemical species. Thus, the manganese hexacyanoferrate hydrate nanocube electrode shows a good rate capability and cycling stability for electrochemical capacitors. Furthermore, electrodes modified with manganese hexacyanoferrate hydrate nanocubes demonstrate a sensitive electrochemical response to hydrogen peroxide (H2O2) in buffer solutions with a high selectivity. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr04322k

  17. Influence of essential elements on manganese intoxication

    SciTech Connect

    Khandelwal, S.; Ashquin, M.; Tandon, S.K.

    1984-01-01

    With a view to explore the influence of essential metals in manganese intoxication, the effect of calcium, iron or zinc supplementation on the uptake of manganese and on the activity of manganese sensitive enzymes, succinic dehydrogenase and cytochrome oxidase in brain and liver of rat was investigated. The choice of the two mitochondrial enzymes was based on the fact that the mitochondria are the chief site of manganese accumulation and their activity in brain, liver and blood of rats is significantly influenced by manganese.

  18. Impaired manganese metabolism causes mitotic misregulation.

    PubMed

    García-Rodríguez, Néstor; Díaz de la Loza, María del Carmen; Andreson, Bethany; Monje-Casas, Fernando; Rothstein, Rodney; Wellinger, Ralf Erik

    2012-05-25

    Manganese is an essential trace element, whose intracellular levels need to be carefully regulated. Mn(2+) acts as a cofactor for many enzymes and excess of Mn(2+) is toxic. Alterations in Mn(2+) homeostasis affect metabolic functions and mutations in the human Mn(2+)/Ca(2+) transporter ATP2C1 have been linked to Hailey-Hailey disease. By deletion of the yeast orthologue PMR1 we have studied the impact of Mn(2+) on cell cycle progression and show that an excess of cytosolic Mn(2+) alters S-phase transit, induces transcriptional up-regulation of cell cycle regulators, bypasses the need for S-phase cell cycle checkpoints and predisposes to genomic instability. On the other hand, we find that depletion of the Golgi Mn(2+) pool requires a functional morphology checkpoint to avoid the formation of polyploid cells. PMID:22493290

  19. Synthesis, characterization, optical and sensing property of manganese oxide nanoparticles

    SciTech Connect

    Manigandan, R.; Suresh, R.; Giribabu, K.; Narayanan, V.; Vijayalakshmi, L.; Stephen, A.

    2014-01-28

    Manganese oxide nanoparticles were prepared by thermal decomposition of manganese oxalate. Manganese oxalate was synthesized by reacting 1:1 mole ratio of manganese acetate and ammonium oxalate along with sodium dodecyl sulfate (SDS). The structural characterization of manganese oxalate and manganese oxide nanoparticles was analyzed by XRD. The XRD spectrum confirms the crystal structure of the manganese oxide and manganese oxalate. In addition, the average grain size, lattice parameter values were also calculated using XRD spectrum. Moreover, the diffraction peaks were broadened due to the smaller size of the particle. The band gap of manganese oxide was calculated from optical absorption, which was carried out by DRS UV-Visible spectroscopy. The morphology of manganese oxide nanoparticles was analyzed by SEM images. The FT-IR analysis confirms the formation of the manganese oxide from manganese oxalate nanoparticles. The electrochemical sensing behavior of manganese oxide nanoparticles were investigated using hydrogen peroxide by cyclic voltammetry.

  20. Salmonella Mitigates Oxidative Stress and Thrives in the Inflamed Gut by Evading Calprotectin-Mediated Manganese Sequestration.

    PubMed

    Diaz-Ochoa, Vladimir E; Lam, Diana; Lee, Carlin S; Klaus, Suzi; Behnsen, Judith; Liu, Janet Z; Chim, Nicholas; Nuccio, Sean-Paul; Rathi, Subodh G; Mastroianni, Jennifer R; Edwards, Robert A; Jacobo, Christina M; Cerasi, Mauro; Battistoni, Andrea; Ouellette, André J; Goulding, Celia W; Chazin, Walter J; Skaar, Eric P; Raffatellu, Manuela

    2016-06-01

    Neutrophils hinder bacterial growth by a variety of antimicrobial mechanisms, including the production of reactive oxygen species and the secretion of proteins that sequester nutrients essential to microbes. A major player in this process is calprotectin, a host protein that exerts antimicrobial activity by chelating zinc and manganese. Here we show that the intestinal pathogen Salmonella enterica serovar Typhimurium uses specialized metal transporters to evade calprotectin sequestration of manganese, allowing the bacteria to outcompete commensals and thrive in the inflamed gut. The pathogen's ability to acquire manganese in turn promotes function of SodA and KatN, enzymes that use the metal as a cofactor to detoxify reactive oxygen species. This manganese-dependent SodA activity allows the bacteria to evade neutrophil killing mediated by calprotectin and reactive oxygen species. Thus, manganese acquisition enables S. Typhimurium to overcome host antimicrobial defenses and support its competitive growth in the intestine. PMID:27281571

  1. Transportation.

    ERIC Educational Resources Information Center

    Crank, Ron

    This instructional unit is one of 10 developed by students on various energy-related areas that deals specifically with transportation and energy use. Its objective is for the student to be able to discuss the implication of energy usage as it applies to the area of transportation. Some topics covered are efficiencies of various transportation…

  2. Environmental Controls of Biological Manganese Oxidation

    NASA Astrophysics Data System (ADS)

    Belz, A. P.; Ahn, C. C.; Nealson, K. H.

    2001-12-01

    Biological catalysis of manganese oxidation represents an important contribution to global manganese cycling; biological oxidation rates are several orders of magnitude higher than those of abiotic processes. Despite recent genetics advances, ongoing behavioral studies, and a large pool of knowledge regarding manganese chemistry, the links between biology and environmental chemistry remain unresolved. We have performed experiments on batch cultures of Leptothrix discophora SS-1 to explore the physiology of biological manganese oxidation. We have further conducted spectroscopic and microscopic studies of the mechanism as manganese proceeds from the soluble Mn2+ species to the insoluble Mn(III) and Mn(IV) phases. These investigations suggest roles for aqueous chemistry, mineralogy, and microbial physiology in controlling manganese fluxes in metal-rich environments.

  3. Mapping prefrontal circuits in vivo with manganese-enhanced magnetic resonance imaging in monkeys.

    PubMed

    Simmons, Janine M; Saad, Ziad S; Lizak, Martin J; Ortiz, Michael; Koretsky, Alan P; Richmond, Barry J

    2008-07-23

    Manganese-enhanced magnetic resonance imaging (MEMRI) provides a powerful tool to study multisynaptic circuits in vivo and thereby to link information about neural structure and function within individual subjects. Making the best use of MEMRI in monkeys requires minimizing manganese-associated neurotoxicity, maintaining sensitivity to manganese-dependent signal changes and mapping transport throughout the brain without a priori anatomical hypotheses. Here, we performed intracortical injections of isotonic MnCl(2), comparisons of preinjection and postinjection scans, and voxelwise statistical mapping. Isotonic MnCl(2) did not cause cell death at the injection site, damage to downstream targets of manganese transport, behavioral deficits, or changes in neuronal responsiveness. We detected and mapped manganese transport throughout cortical-subcortical circuits by using voxelwise statistical comparisons of at least 10 preinjection and two postinjection scans. We were able to differentiate between focal and diffuse projection fields and to distinguish between the topography of striatal projections from orbitofrontal and anterior cingulate cortex in a single animal. This MEMRI approach provides a basis for combining circuit-based anatomical analyses with simultaneous single-unit recordings and/or functional magnetic resonance imaging in individual monkeys. Such studies will enhance our interpretations of functional data and our understanding of how neuronal activity is transformed as it propagates through a circuit. PMID:18650340

  4. [Clinical cases of occupational chronic manganese intoxication].

    PubMed

    Konstantinova, T N; Lakhman, O L; Katamanova, E V; Kartapol'tseva, N V; Meshcheriagin, V A; Rusanova, D V; Andreeva, O K

    2009-01-01

    Classic symptoms of manganese intoxication are very rarely seen nowadays. Clinic in Angarsk Research Institute for Occupational medicine and Human ecology registered two cases of stage I and II chronic manganese intoxication over 10 years among electric welders. The cases were diagnosed with consideration of long length of exposure to manganese with the ambient air level exceeding the MAC 1.5 times, the disease manifestation at middle age, high manganese level in serum and urine, characteristic neurologic symptoms in association with organic psychopathologic defects and polyneuropathy of limbs. PMID:19278189

  5. Negative impact of manganese on honeybee foraging

    PubMed Central

    Søvik, Eirik; Perry, Clint J.; LaMora, Angie; Barron, Andrew B.; Ben-Shahar, Yehuda

    2015-01-01

    Anthropogenic accumulation of metals such as manganese is a well-established health risk factor for vertebrates. By contrast, the long-term impact of these contaminants on invertebrates is mostly unknown. Here, we demonstrate that manganese ingestion alters brain biogenic amine levels in honeybees and fruit flies. Furthermore, we show that manganese exposure negatively affects foraging behaviour in the honeybee, an economically important pollinator. Our findings indicate that in addition to its direct impact on human health, the common industrial contaminant manganese might also have indirect environmental and economical impacts via the modulation of neuronal and behavioural functions in economically important insects. PMID:25808001

  6. MntR(Rv2788): a transcriptional regulator that controls manganese homeostasis in Mycobacterium tuberculosis.

    PubMed

    Pandey, Ruchi; Russo, Riccardo; Ghanny, Saleena; Huang, Xiaojuan; Helmann, John; Rodriguez, G Marcela

    2015-12-01

    The pathogenic mycobacterium Mycobacterium tuberculosis encodes two members of the DtxR/MntR family of metalloregulators, IdeR and SirR. IdeR represses gene expression in response to ferrous iron, and we here demonstrate that SirR (Rv2788), although also annotated as an iron-dependent repressor, functions instead as a manganese-dependent transcriptional repressor and is therefore renamed MntR. MntR regulates transporters that promote manganese import and genes that respond to metal ion deficiency such as the esx3 system. Repression of manganese import by MntR is essential for survival of M. tuberculosis under conditions of high manganese availability, but mntR is dispensable during infection. In contrast, manganese import by MntH and MntABCD was found to be indispensable for replication of M. tuberculosis in macrophages. These results suggest that manganese is limiting in the host and that interfering with import of this essential metal may be an effective strategy to attenuate M. tuberculosis. PMID:26337157

  7. Manganese nodules: thorium-230: protactinium-231 ratios.

    PubMed

    Sackett, W M

    1966-11-01

    The Th(230): Pa(231) activity ratio in 7 of 11 manganese nodules is less than 10.8, the theoretical production ratio of activities in the ocean. This finding indicates difierential accumulation of these nuclides in authigenic deposits of manganese-iron oxide. PMID:17778807

  8. 21 CFR 582.5461 - Manganese sulfate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Manganese sulfate. 582.5461 Section 582.5461 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5461 Manganese sulfate....

  9. 21 CFR 582.5452 - Manganese gluconate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Manganese gluconate. 582.5452 Section 582.5452 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5452 Manganese gluconate....

  10. 21 CFR 582.5446 - Manganese chloride.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Manganese chloride. 582.5446 Section 582.5446 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5446 Manganese chloride....

  11. 21 CFR 582.5449 - Manganese citrate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Manganese citrate. 582.5449 Section 582.5449 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5449 Manganese citrate....

  12. 21 CFR 73.2775 - Manganese violet.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2775 Manganese violet. (a) Identity. The color additive... less than 93 percent. (c) Uses and restrictions. Manganese violet is safe for use in coloring cosmetics generally, including cosmetics applied to the area of the eye, in amounts consistent with good...

  13. 21 CFR 73.2775 - Manganese violet.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2775 Manganese violet. (a) Identity. The color additive... less than 93 percent. (c) Uses and restrictions. Manganese violet is safe for use in coloring cosmetics generally, including cosmetics applied to the area of the eye, in amounts consistent with good...

  14. 21 CFR 73.2775 - Manganese violet.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2775 Manganese violet. (a) Identity. The color additive... less than 93 percent. (c) Uses and restrictions. Manganese violet is safe for use in coloring cosmetics generally, including cosmetics applied to the area of the eye, in amounts consistent with good...

  15. Manganese peroxidase gene transcription in Phanerochaete chrysosporium: Activation by manganese

    SciTech Connect

    Brown, J.A.; Alic, M. Gold, M.H. )

    1991-07-01

    The expression of manganese peroxidase in nitrogen-limited cultures of Phanerochaete chrysosporium is dependent on Mn, and initial work suggested that Mn regulates transcription of the mnp gene. In this study, using Northern (RNA) blot analysis of kinetic, dose-response, and inhibitor experiments, the authors demonstrate unequivocally that Mn regulates mnp gene transcription. The amount of mnp mRNA in cells of 4-day-old nitrogen-limited cultures is a direct function of the concentration of Mn in the culture medium up to a maximum of 180 {mu}M. Addition of Mn to nitrogen-limited Mn-deficient secondary metabolic (4-, 5-, and 6-day-old) cultures results in the appearance of mnp mRNA within 40 min. The appearance of this message is completely inhibited by the RNA synthesis inhibitor dactinomycin but not by the protein synthesis inhibitor cycloheximide. Furthermore, the amount of mnp mRNA produced is a direct function of the concentration of added Mn. In contrast, addition of Mn to low-nitrogen Mn-deficient 2- or 3-day-old cultures does not result in the appearance of mnp mRNA. Manganese peroxidase protein is detected by specific immunoprecipitation of the in vitro translation products of poly(A) RNA isolated from Mn-supplemented (but nor from Mn-deficient) cells. All of these results demonstrate that Mn, the substrate for the enzyme, regulates mnp gene transcription via a growth-stage-specific and concentration-dependent mechanism.

  16. Groundwater, iron and manganese an unwelcome trio

    SciTech Connect

    Kothari, N. )

    1988-02-01

    Iron and manganese are natural constituents of the earth's crust and both elements create serious aesthetic problems in drinking water supplies. The occurrence of iron and manganese in groundwater, and problems arising from their presence, are reviewed. Four commonly used methods for iron and manganese removal are direct oxidation, addition of oxidation agents, ion exchange, and stabilization. These methods are discussed, as well as factors affecting iron and manganese removal, such as temperature, pH, dissolved oxygen, alkalinity, and other ions present. The above factors affect the removal methods differently and for these reasons, laboratory testing and studies should be made to evaluate the treatability of a water supply for iron and manganese removal.

  17. Manganese oxidation by Leptothrix discophora.

    PubMed

    Boogerd, F C; de Vrind, J P

    1987-02-01

    Cells of Leptothrix discophora SS1 released Mn2+-oxidizing factors into the medium during growth in batch culture. Manganese was optimally oxidized when the medium was buffered with HEPES (N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid) at pH 7.5. Manganese-oxidizing activity in the culture medium in which this strain had been grown previously was sensitive to heat, phosphate, Tris, NaN3, HgCl2 NaCl, sodium dodecyl sulfate, and pronase; 0.5 mol of O2 was consumed per mol of MnO2 formed. During Mn2+ oxidation, protons were liberated. With sodium dodecyl sulfate-polyacrylamide gel electrophoresis, two protein-containing bands were detected in the spent culture medium. One band had an apparent molecular weight of 110,000 and was predominant in Mn2+-oxidizing activity. The second product (Mr 85,000) was only detected in some cases and probably represents a proteolytic breakdown moiety of the 110,000-Mr protein. The Mn2+-oxidizing factors were associated with the MnO2 aggregates that had been formed in spent culture medium. After solubilization of this MnO2 with ascorbate, Mn2+-oxidizing activity could be recovered. PMID:3804969

  18. Iron and manganese removal by using manganese ore constructed wetlands in the reclamation of steel wastewater.

    PubMed

    Xu, Jing-Cheng; Chen, Gu; Huang, Xiang-Feng; Li, Guang-Ming; Liu, Jia; Yang, Na; Gao, Sai-Nan

    2009-09-30

    To reclaim treated steel wastewater as cooling water, manganese ore constructed wetland was proposed in this study for the removal of iron and manganese. In lab-scale wetlands, the performance of manganese ore wetland was found to be more stable and excellent than that of conventional gravel constructed wetland. The iron and manganese concentration in the former was below 0.05 mg/L at hydraulic retention time of 2-5 days when their influent concentrations were in the range of 0.16-2.24 mg/L and 0.11-2.23 mg/L, respectively. Moreover, its removals for COD, turbidity, ammonia nitrogen and total phosphorus were 55%, 90%, 67% and 93%, respectively, superior to the corresponding removals in the gravel wetland (31%, 86%, 58% and 78%, respectively). The good performance of manganese ore was ascribed to the enhanced biological manganese removal with the aid of manganese oxide surface and the smaller size of the medium. The presence of biological manganese oxidation was proven by the facts of good manganese removal in wetlands at chemical unfavorable conditions (such as ORP and pH) and the isolation of manganese oxidizing strains from the wetlands. Similar iron and manganese removal was later observed in a pilot-scale gravel-manganese-ore constructed wetland, even though the manganese ore portion in total volume was reduced from 100% (in the lab-scale) to only 4% (in the pilot-scale) for the sake of cost-saving. The quality of the polished wastewater not only satisfied the requirement for cooling water but also suitable as make-up water for other purposes. PMID:19443107

  19. Expression of an "Arabidopsis CAX2" variant in potato tubers increases calcium levels with no accumulation of manganese

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Previously, we made a chimeric "Arabidopsis thaliana" vacuolar transporter CAX2B [a variant of N-terminus truncated form of CAX2 (sCAX2) containing the "B" domain from CAX1] that has enhanced calcium (Ca[2+]) substrate specificity and lost the manganese (Mn[2+]) transport capability of sCAX2. Here, ...

  20. Manganese Neurotoxicity: A Focus on the Neonate

    PubMed Central

    Erikson, Keith M.; Thompson, Khristy; Aschner, Judy; Aschner, Michael

    2007-01-01

    Manganese (Mn) is an essential trace metal found in all tissues, and it is required for normal amino acid, lipid, protein, and carbohydrate metabolism. While Mn deficiency is extremely rare in humans, toxicity due to overexposure of Mn is more prevalent. The brain appears to be especially vulnerable. Mn neurotoxicity is most commonly associated with occupational exposure to aerosols or dusts that contain extremely high levels (> 1-5 mg Mn/m3) of Mn, consumption of contaminated well water, or parenteral nutrition therapy in patients with liver disease or immature hepatic functioning such as the neonate. This review will focus primarily on the neurotoxicity of Mn in the neonate. We will discuss putative transporters of the metal in the neonatal brain and then focus on the implications of high Mn exposure to the neonate focusing on typical exposure modes (e.g., dietary and parenteral). Although Mn exposure via parenteral nutrition is uncommon in adults, in premature infants, it is more prevalent, so this mode of exposure becomes salient in this population. We will briefly review some of the mechanisms of Mn neurotoxicity and conclude with a discussion of ripe areas for research in this underreported area of neurotoxicity. PMID:17084903

  1. Manganese homeostasis and utilization in pathogenic bacteria.

    PubMed

    Juttukonda, Lillian J; Skaar, Eric P

    2015-07-01

    Manganese (Mn) is a required cofactor for all forms of life. Given the importance of Mn to bacteria, the host has devised strategies to sequester Mn from invaders. In the macrophage phagosome, NRAMP1 removes Mn and other essential metals to starve intracellular pathogens; in the extracellular space, calprotectin chelates Mn and Zn. Calprotectin-mediated Mn sequestration is a newly appreciated host defense mechanism, and recent findings are highlighted herein. In order to acquire Mn when extracellular concentrations are low, bacteria have evolved efficient Mn acquisition systems that are under elegant transcriptional control. To counteract Mn overload, some bacteria possess Mn-specific export systems that are important in vivo, presumably for control of intracellular Mn levels. Mn transporters, their transcriptional regulators and some Mn-requiring enzymes are necessary for virulence of certain bacterial pathogens, as revealed by animal models of infection. Furthermore, Mn is an important facet of the cellular response to oxidative stress, a host antibacterial strategy. The battle for Mn between host and pathogen is now appreciated to be a major determinant of the outcome of infection. In this MicroReview, the contribution of Mn to the host-pathogen interaction is reviewed, and key questions are proposed for future study. PMID:25898914

  2. The genesis of manganese concretions in the Igarra area, Southwestern Nigeria

    NASA Astrophysics Data System (ADS)

    Bafor, B. E.; Mücke, A.

    An unusual supergene manganese enrichment occurs in the Igarra Formation within the schist belt of southwestern Nigeria. The manganese occurs mainly as peanut-size pisolitic grains or spherical concretions in the weathered schistose units within the formation. The mineralogy of the weathered schists consists of irregularly shaped quartz grains of varying sizes embedded in a matrix composed mainly of sheet-silicates, organic materials and heavy minerals (mostly oxides) which have been almost completely replaced by todorokite. The most abundant of these heavy minerals was probably ilnenite (FeTiO 3) which has now been transformed into pseudo-rutile (Fe 2Ti 3O 9) by the leaching of iron. Ore microscopic studies reveal that the concretions have essentially the same mineralogy as the weathered host rock. But in addition, they also contain some plant remains in the form of decomposing cellular tissues which are generally either completely or partly replaced by todorokite which also replaces the surrounding cement. Microprobe analysis of relicts of the original cement indicates that it was initially thuringitic to chamositic in composition, with FeO content of about 38 weight %. Manganese replacement of the cement was at various stages. The final product of the enrichment process contained over 70 % MnO while the FeO value decreased to only about 2 %. The unusual aspect of this enrichment is the reversal in the usual process of separation of manganese from iron. The reversal is explained as resulting from the transportation of the two elements in the supergene solution in the form of organo-metallic complexes. The manganese complex, being less stable than the iron complex, was precipitated around spots defined by relicts of decomposing plant materials whcih formed a geochemical manganese barrier, while the more stable iron complex still remained in solution. Subsequent erosion concentrated the manganese-rich spots into resistant concretions paving the present surface of

  3. Manganese concentrate usage in steelmaking

    NASA Astrophysics Data System (ADS)

    Nokhrina, O. I.; Rozhihina, I. D.

    2015-09-01

    The results of the research process of producing metalized products by solid-phase reduction of iron using solid carbonaceous reducing agents. Thermodynamic modeling was carried out on the model of the unit the Fe-C-O and system with iron ore and coal. As a result of modeling the thermodynamic boundary reducing, oxidizing, and transition areas and the value of the ratio of carbon and oxygen in the system. Simulation of real systems carried out with the gas phase obtained in the pyrolys of coal. The simulation results allow to determine the optimal cost of coal required for complete reduction of iron ore from a given composition. The kinetics of the processes of solid-phase reduction of iron using coal of various technological brands. The paper describes experiments on effects of metal deoxidizer composition, component proportion, pelletizing mixture, particle size distribution of basic materials and flux on manganese recovering from oxides under direct melting.

  4. MANGANESE DIOXIDE METHOD FOR PREPARATION OF PROTACTINIUM

    DOEpatents

    Katzin, L.I.

    1958-08-12

    A method of obtaining U/sup 233/ is described. An aqueous solution of neutriln irradiated thoriunn is treated by forming tberein a precipitate of manganese dioxide which carries and thus separates the Pa/sup 233/ from the solution. The carrier precipitate so formed is then dissolved in an acidic solution containing a reducing agent sufficiently electronegative to reduce the tetravalent manganese to the divalent state. Further purification of the Pa/sup 233/ may be obtained by forming another manganese dioxide carrier precipitate and subsequently dissolving it. Ater a sufficient number of such cycles have brought the Pa/sup 233/ to the desired purity, the solution is aged, allowing the formation ot U/sup 233/ by radioaetive decay. A manganese dioxide precipitate is then formed in the U/sup 233/ containing solution. This precipitate carries down any remaining Pa/sup 233/ thus leaving the separated U/sup 233/solution, from whieh it may be easily recovered.

  5. 21 CFR 184.1461 - Manganese sulfate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... manganese compounds with sulfuric acid. It is also obtained as a byproduct in the manufacture of... dioxide in sulfuric acid, and the roasting of pyrolusite (MnO2) ore with solid ferrous sulfate and...

  6. A manganese oxidation model for rivers

    SciTech Connect

    Hess, G.W. ); Kim, Byung R. ); Roberts, P.J.W. )

    1989-04-01

    The presence of manganese in natural waters (>0.05 mg/L) degrades water-supply quality. A model was devised to predict the variation of manganese concentrations in river water released from an impoundment with the distance downstream. The model is one-dimensional and was calibrated using dissolved oxygen, biochemical oxygen demand, pH, manganese, and hydraulic data collected in the Duck River, Tennessee. The results indicated that the model can predict manganese levels under various conditions. The model was then applied to the Chattahoochee River, Georgia. Discrepancies between observed and predicted may be due to inadequate pH data, precipitation of sediment particles, unsteady flow conditions in the Chattahoochee River, inaccurate rate expressions for the los pH conditions, or their combinations.

  7. Biological manganese oxidation by Pseudomonas putida in trickling filters.

    PubMed

    McKee, Kyle P; Vance, Cherish C; Karthikeyan, Raghupathy

    2016-06-01

    Biological oxidation has been researched as a viable alternative for treating waters with high manganese (Mn) concentrations, typically found in mine drainage or in some geological formations. In this study, laboratory-scale trickling filters were constructed to compare the Mn removal efficiency between filters inoculated with the Mn oxidizing bacteria, Pseudomonas putida, and filters without inoculation. Manganese oxidation and removal was found to be significantly greater in trickling filters with Pseudomonas putida after startup times of only 48 h. Mn oxidation in Pseudomonas putida inoculated trickling filters was up to 75% greater than non-inoculated filters. One-dimensional advective-dispersive models were formulated to describe the transport of Mn in trickling filter porous media. Based on the experimental transport parameters obtained, the model predicted that a filter depth of only 16 cm is needed to reduce influent concentration of 10 mg L(-1) to 0.05 mg L(-1). PMID:26943637

  8. Manganese recycling in the United States in 1998

    USGS Publications Warehouse

    Jones, Thomas S.

    2001-01-01

    This report describes the flow and processing of manganese within the U.S. economy in 1998 with emphasis on the extent to which manganese is recycled. Manganese was used mostly as an alloying agent in alloys in which it was a minor component. Manganese was recycled mostly within scrap of iron and steel. A small amount was recycled within aluminum used beverage cans. Very little manganese was recycled from materials being recovered specifically for their manganese content. For the United States in 1998, 218,000 metric tons of manganese was estimated to have been recycled from old scrap, of which 96% was from iron and steel scrap. Efficiency of recycling was estimated as 53% and recycling rate as 37%. Metallurgical loss of manganese was estimated to be about 1.7 times that recycled. This loss was mostly into slags from iron and steel production, from which recovery of manganese has yet to be shown economically feasible.

  9. Toenail, Blood and Urine as Biomarkers of Manganese Exposure

    PubMed Central

    Laohaudomchok, Wisanti; Lin, Xihong; Herrick, Robert F.; Fang, Shona C.; Cavallari, Jennifer M.; Christiani, David C.; Weisskopf, Marc G.

    2011-01-01

    Objective This study examined the correlation between manganese exposure and manganese concentrations in different biomarkers. Methods Air measurement data and work histories were used to determine manganese exposure over a workshift and cumulative exposure. Toenail samples (n=49), as well as blood and urine before (n=27) and after (urine, n=26; blood, n=24) a workshift were collected. Results Toenail manganese, adjusted for age and dietary manganese, was significantly correlated with cumulative exposure in months 7-9, 10-12, and 7-12 before toenail clipping date, but not months 1-6. Manganese exposure over a work shift was not correlated with changes in blood nor urine manganese. Conclusions Toenails appeared to be a valid measure of cumulative manganese exposure 7 to 12 months earlier. Neither change in blood nor urine manganese appeared to be suitable indicators of exposure over a typical workshift. PMID:21494156

  10. Autonomic function in manganese alloy workers

    SciTech Connect

    Barrington, W.W.; Angle, C.R.; Willcockson, N.K.; Padula, M.A.; Korn, T.

    1998-07-01

    The observation of orthostatic hypotension in an index case of manganese toxicity lead to this prospective attempt to evaluate cardiovascular autonomic function and cognitive and emotional neurotoxicity in eight manganese alloy welders and machinists. The subjects consisted of a convenience sample consisting of an index case of manganese dementia, his four co-workers in a frog shop for gouging, welding, and grinding repair of high manganese railway track and a convenience sample of three mild steel welders with lesser manganese exposure also referred because of cognitive or autonomic symptoms. Frog shop air manganese samples 9.6--10 years before and 1.2--3.4 years after the diagnosis of the index case exceeded 1.0 mg/m{sup 3} in 29% and 0.2 mg/m{sup 3} in 62%. Twenty-four-hour electrocardiographic (Holter) monitoring was used to determine the temporal variability of the heartrate (RR{prime} interval) and the rates of change at low frequency and high frequency. MMPI and MCMI personality assessment and short-term memory, figure copy, controlled oral word association, and symbol digit tests were used.

  11. Manganese mineralogy and diagenesis in the sedimentary rock record

    NASA Astrophysics Data System (ADS)

    Johnson, Jena E.; Webb, Samuel M.; Ma, Chi; Fischer, Woodward W.

    2016-01-01

    Oxidation of manganese (II) to manganese (III,IV) demands oxidants with very high redox potentials; consequently, manganese oxides are both excellent proxies for molecular oxygen and highly favorable electron acceptors when oxygen is absent. The first of these features results in manganese-enriched sedimentary rocks (manganese deposits, commonly Mn ore deposits), which generally correspond to the availability of molecular oxygen in Earth surface environments. And yet because manganese reduction is promoted by a variety of chemical species, these ancient manganese deposits are often significantly more reduced than modern environmental manganese-rich sediments. We document the impacts of manganese reduction and the mineral phases that form stable manganese deposits from seven sedimentary examples spanning from modern surface environments to rocks over 2 billion years old. Integrating redox and coordination information from synchrotron X-ray absorption spectroscopy and X-ray microprobe imaging with scanning electron microscopy and energy and wavelength-dispersive spectroscopy, we find that unlike the Mn(IV)-dominated modern manganese deposits, three manganese minerals dominate these representative ancient deposits: kutnohorite (CaMn(CO3)2), rhodochrosite (MnCO3), and braunite (Mn(III)6Mn(II)O8SiO4). Pairing these mineral and textural observations with previous studies of manganese geochemistry, we develop a paragenetic model of post-depositional manganese mineralization with kutnohorite and calcian rhodochrosite as the earliest diagenetic mineral phases, rhodochrosite and braunite forming secondarily, and later alteration forming Mn-silicates.

  12. Magnetotransport in Pulsed Laser Deposited Manganese Doped Lead Sulfide Films

    NASA Astrophysics Data System (ADS)

    Rimal, Gaurab; Sapkota, Keshab; Maksymov, Artur; Spinu, Leonard; Wang, Wenyong; Tang, Jinke

    Diluted magnetic semiconductors (DMS) have been proposed as promising candidates for spintronic applications. Most research in this field has been confined to III-V and II-VI semiconductor system. There are reports on IV-VI semiconductors, however reports on lead sulfide (PbS) based DMS is limited. We study the transport, magnetic and structural properties of manganese doped lead sulfide (Mn:PbS) films produced by pulsed laser deposition (PLD). The films are found to show hopping transport at low tempeature. Low temperature magnetoresistance (MR) studies show that the sign of MR can be changed by application of gate voltage. The magnetic properties of the films were also studied which showed ferromagnetic behavior at room temperature.

  13. Manganese-induced Neurotoxicity: From C. elegans to Humans

    PubMed Central

    Chen, Pan; Chakraborty, Sudipta; Peres, Tanara V.; Bowman, Aaron B.; Aschner, Michael

    2014-01-01

    Manganese (Mn) is one of the most abundant metals on the earth. It is required for normal cellular activities, but overexposure leads to toxicity. Neurons are more susceptible to Mn-induced toxicity than other cells, and accumulation of Mn in the brain results in Manganism that presents with Parkinson's disease (PD)-like symptoms. In the last decade, a number of Mn transporters have been identified, which improves our understanding of Mn transport in and out of cells. However, the mechanism of Mn-induced neurotoxicity is only partially uncovered, with further research needed to explore the whole picture of Mn-induced toxicity. In this review, we will address recent progress in Mn-induced neurotoxicity from C. elegans to humans, and explore future directions that will help understand the mechanisms of its neurotoxicity. PMID:25893090

  14. Biogeochemical cycling of manganese in Oneida Lake, New York: whole lake studies of manganese

    NASA Technical Reports Server (NTRS)

    Aguilar, C.; Nealson, K. H.

    1998-01-01

    Oneida Lake, New York is a eutrophic freshwater lake known for its abundant manganese nodules and a dynamic manganese cycle. Temporal and spatial distribution of soluble and particulate manganese in the water column of the lake were analyzed over a 3-year period and correlated with other variables such as oxygen, pH, and temperature. Only data from 1988 are shown. Manganese is removed from the water column in the spring via conversion to particulate form and deposited in the bottom sediments. This removal is due to biological factors, as the lake Eh/pH conditions alone can not account for the oxidation of the soluble manganese Mn(II). During the summer months the manganese from microbial reduction moves from the sediments to the water column. In periods of stratification the soluble Mn(II) builds up to concentrations of 20 micromoles or more in the bottom waters. When mixing occurs, the soluble Mn(II) is rapidly removed via oxidation. This cycle occurs more than once during the summer, with each manganese atom probably being used several times for the oxidation of organic carbon. At the end of the fall, whole lake concentrations of manganese stabilize, and remain at about 1 micromole until the following summer, when the cycle begins again. Inputs and outflows from the lake indicate that the active Mn cycle is primarily internal, with a small accumulation each year into ferromanganese nodules located in the oxic zones of the lake.

  15. Study of high performance alloy electroforming. [nickel manganese and nickel cobalt manganese alloys

    NASA Technical Reports Server (NTRS)

    Malone, G. A.

    1984-01-01

    Nickel-manganese alloy electrodeposits from an electrolyte containing more manganese ion than previously used is being evaluated at two bath operating temperatures with a great variety of pulse plating conditions. Saccharine was added as a stress reducing agent for the electroforming of several of the samples with highest manganese content. All specimens for mechanical property testing have been produced but are not through the various heat treatments as yet. One of the heat treatment will be at 343 C (650 F), the temperature at which the MCC outer electroformed nickel shell is stress relieved. A number of retainer specimens from prior work have been tested for hardness before and after heat treatment. There appears to be a fairly good correlation between hardness and mechanical properties. Comparison of representative mechanical properties with hardnesses are made for nickel-manganese electrodeposits and nickel-cobalt-manganese deposits.

  16. Manganese-electrolysed slag treatment: bioleaching of manganese by Fusarium sp.

    PubMed

    Cao, Jian-Bing; Li, Xiao-Ming; Ouyang, Yu-Zhu; Zheng, Wei; Wang, Dong-Bo; Shen, Ting-Ting; Yue, Xiu; Yang, Qia

    2012-06-01

    A fungi strain named Fusarium sp. was isolated from manganese-electrolysed slag by using a gradient dilution spread plate method, identified by 26S RNA sequence analysis and phylogenetic tree analysis, and explored for the bioleaching capacity to manganese (II) from manganese-electrolysed slag in liquid mineral medium under different environmental conditions, including system temperature, incubator rotation speed and initial pH value. DNA sequence and phylogenetic analysis indicated the name of this fungi strain, that is, Fusarium sp., and higher bioleaching efficiencies (71.6%) of manganese by this fungi were observed when the bioleaching was carried out under the optimized conditions as follows: contact time: 72 h; system temperature: 28 degrees C; inoculums concentration: 2% (v/v); incubator rotation speed: 150 rpm; pH 4.0. Because of its low cost, environment friendliness and better efficiency, the bioleaching technique will have a significant impact on manganese-electrolysed slag pollution mitigation. PMID:22856303

  17. Biological Superoxide In Manganese Oxide Formation

    NASA Astrophysics Data System (ADS)

    Hansel, C.; Learman, D.; Zeiner, C.; Santelli, C. M.

    2011-12-01

    Manganese (Mn) oxides are among the strongest sorbents and oxidants within the environment, controlling the fate and transport of numerous elements and the degradation of recalcitrant carbon. Both bacteria and fungi mediate the oxidation of Mn(II) to Mn(III/IV) oxides but the genetic and biochemical mechanisms responsible remain poorly understood. Furthermore, the physiological basis for microbial Mn(II) oxidation remains an enigma. We have recently reported that a common marine bacterium (Roseobacter sp. AzwK-3b) oxidizes Mn(II) via reaction with extracellular superoxide (O2-) produced during exponential growth. Here we expand this superoxide-mediated Mn(II) oxidation pathway to fungi, introducing a surprising homology between prokaryotic and eukaryotic metal redox processes. For instance, Stibella aciculosa, a common soil Ascomycete filamentous fungus, precipitates Mn oxides at the base of asexual reproductive structures (synnemata) used to support conidia (Figure 1). This distribution is a consequence of localized production of superoxide (and it's dismutation product hydrogen peroxide, H2O2), leading to abiotic oxidation of Mn(II) by superoxide. Disruption of NADPH oxidase activity using the oxidoreductase inhibitor DPI leads to diminished cell differentiation and subsequent Mn(II) oxidation inhibition. Addition of Cu(II) (an effective superoxide scavenger) leads to a concentration dependent decrease in Mn oxide formation. We predict that due to the widespread production of extracellular superoxide within the fungal and likely bacterial kingdoms, biological superoxide may be an important contributor to the cycling of Mn, as well as other metals (e.g., Hg, Fe). Current and future explorations of the genes and proteins involved in superoxide production and Mn(II) oxidation will ideally lend insight into the physiological and biochemical basis for these processes.

  18. Antioxidants and NOS inhibitors selectively targets manganese-induced cell volume via Na-K-Cl cotransporter-1 in astrocytes.

    PubMed

    Alahmari, Khalid A; Prabhakaran, Harini; Prabhakaran, Krishnan; Chandramoorthy, Harish C; Ramugounder, Ramakrishnan

    2015-06-12

    Manganese has shown to be involved in astrocyte swelling. Several factors such as transporters, exchangers and ion channels are attributed to astrocyte swelling as a result in the deregulation of cell volume. Products of oxidation and nitration have been implied to be involved in the pathophysiology of swelling; however, the direct link and mechanism of manganese induced astrocyte swelling has not been fully elucidated. In the current study, we used rat primary astrocyte cultures to investigate the activation of Na-K-Cl cotransporter-1 (NKCC1) a downstream mechanism for free radical induced astrocyte swelling as a result of manganese toxicity. Our results showed manganese, oxidants and NO donors as potent inducer of oxidation and nitration of NKCC1. Our results further confirmed that manganese (50 μM) increased the total protein, phosphorylation and activity of NKCC1 as well as cell volume (p < 0.05 vs. control). NKCC1 inhibitor (bumetanide), NKCC1-siRNA, antioxidants; DMTU, MnTBAP, tempol, catalase and Vit-E, NOS inhibitor; L-NAME, peroxinitrite scavenger; uric acid all significantly reversed the effects of NKCC1 activation (p < 0.05). From the current investigation we infer that manganese or oxidants and NO induced activation, oxidation/nitration of NKCC1 play an important role in the astrocyte swelling. PMID:25817889

  19. The diagnosis of manganese-induced parkinsonism.

    PubMed

    Cersosimo, Maria G; Koller, William C

    2006-05-01

    Parkinsonism is a clinical syndrome consisting of tremor, bradykinesia, rigidity, gait, balance problems, in addition to various non-motor symptoms. There are many causes of parkinsonism such as neurodegenerative disease, drugs, vascular causes, structural lesions, infections, and toxicants. Parkinson's disease, or idiopathic parkinsonism, is the most common form of parkinsonism observed in the clinic. There is degeneration of the substantia nigra, pars compacta, which results in loss of striatal dopamine. Parkinson's disease is a slowly progressive condition in which there is a dramatic and sustained responsiveness to levodopa therapy. Manganese is an essential trace element that can be associated with neurotoxicity. Hypermanganism can occur in a variety of clinical settings. The clinical symptoms of manganese intoxication include non-specific complaints, neurobehavioral changes, parkinsonism, and dystonia. Although the globus pallidus is the main structure of damage, other basal ganglia areas can also be involved. MRI scans may show globus pallidus changes during (and for a short period after) exposure. Fluorodopa PET scans that assess the integrity of the substantia nigra dopaminergic system are abnormal in Parkinson's disease. However, these scans re-reported to be normal in a few cases studied with manganese-induced parkinsonism. The parkinsonism due to manganese may have some clinical features that occur less commonly in Parkinson's disease, such as kinetic tremor, dystonia, specific gait disturbances, and early mental, balance and speech changes. The clinical signs tend to be bilateral whereas Parkinson's disease begins on one side of the body. Patients with manganese-induced parkinsonism may be younger at the onset of the disease than with Parkinson's disease. Lastly, there appears to be a lack of response to levodopa therapy in manganese-induced parkinsonism. In summary it may be possible to differentiate manganese-induced parkinsonism from Parkinson

  20. Cardiovascular Toxicities Upon Manganese Exposure

    PubMed Central

    Jiang, Yueming; Zheng, Wei

    2014-01-01

    Manganese (Mn)-induced Parkinsonism has been well documented; however, little attention has been devoted to Mn-induced cardiovascular dysfunction. This review summarizes literature data from both animal and human studies on Mn’s effect on cardiovascular function. Clinical and epidemiological evidence suggests that the incidence of abnormal electrocardiogram (ECG) is significantly higher in Mn-exposed workers than that in the control subjects. The main types of abnormal ECG include sinus tachycardia, sinus bradycardia, sinus arrhythmia, sinister megacardia, and ST-T changes. The accelerated heartbeat and shortened P-R interval appear to be more prominent in female exposed workers than in their male counterparts. Mn-exposed workers display a mean diastolic blood pressure that is significantly lower than that of the control subjects, especially in the young and female exposed workers. Animal studies indicate that Mn is capable of quickly accumulating in heart tissue, resulting in acute or sub-acute cardiovascular disorders, such as acute cardiodepression and hypotension. These toxic outcomes appear to be associated with Mn-induced mitochondrial damage and interaction with the calcium channel in the cardiovascular system. PMID:16382172

  1. Widespread distribution of ability to oxidize manganese among freshwater bacteria.

    PubMed

    Gregory, E; Staley, J T

    1982-08-01

    Manganese-oxidizing heterotrophic bacteria were found to comprise a significant proportion of the bacterial community of Lake Washington (Seattle, Wash.) and Lake Virginia (Winter Park, Fla.). Identification of these freshwater bacteria showed that members of a variety of genera are capable of oxidizing manganese. Isolates maintained in the laboratory spontaneously lost the ability to oxidize manganese. A direct correlation was found between the presence of plasmid DNA and the ability of the organism to oxidize manganese. PMID:16346084

  2. Real-Time Manganese Phase Dynamics during Biological and Abiotic Manganese Oxide Reduction.

    PubMed

    Johnson, Jena E; Savalia, Pratixa; Davis, Ryan; Kocar, Benjamin D; Webb, Samuel M; Nealson, Kenneth H; Fischer, Woodward W

    2016-04-19

    Manganese oxides are often highly reactive and easily reduced, both abiotically, by a variety of inorganic chemical species, and biologically during anaerobic respiration by microbes. To evaluate the reaction mechanisms of these different reduction routes and their potential lasting products, we measured the sequence progression of microbial manganese(IV) oxide reduction mediated by chemical species (sulfide and ferrous iron) and the common metal-reducing microbe Shewanella oneidensis MR-1 under several endmember conditions, using synchrotron X-ray spectroscopic measurements complemented by X-ray diffraction and Raman spectroscopy on precipitates collected throughout the reaction. Crystalline or potentially long-lived phases produced in these experiments included manganese(II)-phosphate, manganese(II)-carbonate, and manganese(III)-oxyhydroxides. Major controls on the formation of these discrete phases were alkalinity production and solution conditions such as inorganic carbon and phosphate availability. The formation of a long-lived Mn(III) oxide appears to depend on aqueous Mn(2+) production and the relative proportion of electron donors and electron acceptors in the system. These real-time measurements identify mineralogical products during Mn(IV) oxide reduction, contribute to understanding the mechanism of various Mn(IV) oxide reduction pathways, and assist in interpreting the processes occurring actively in manganese-rich environments and recorded in the geologic record of manganese-rich strata. PMID:27018915

  3. Essentiality, Toxicity and Uncertainty in the Risk Assessment of Manganese

    EPA Science Inventory

    Risk assessments of manganese by inhalation or oral routes of exposure typically acknowledge the duality of manganese as an essential element at low doses and a toxic metal at high doses. Previously, however, risk assessors were unable to describe manganese pharmacokinetics quant...

  4. Silver manganese oxide electrodes for lithium batteries

    DOEpatents

    Thackeray, Michael M.; Vaughey, John T.; Dees, Dennis W.

    2006-05-09

    This invention relates to electrodes for non-aqueous lithium cells and batteries with silver manganese oxide positive electrodes, denoted AgxMnOy, in which x and y are such that the manganese ions in the charged or partially charged electrodes cells have an average oxidation state greater than 3.5. The silver manganese oxide electrodes optionally contain silver powder and/or silver foil to assist in current collection at the electrodes and to improve the power capability of the cells or batteries. The invention relates also to a method for preparing AgxMnOy electrodes by decomposition of a permanganate salt, such as AgMnO4, or by the decomposition of KMnO4 or LiMnO4 in the presence of a silver salt.

  5. Bacterial manganese reduction and growth with manganese oxide as the sole electron acceptor

    NASA Technical Reports Server (NTRS)

    Myers, Charles R.; Nealson, Kenneth H.

    1988-01-01

    Microbes that couple growth to the reduction of manganese could play an important role in the biogeochemistry of certain anaerobic environments. Such a bacterium, Alteromonas putrefaciens MR-1, couples its growth to the reduction of manganese oxides only under anaerobic conditions. The characteristics of this reduction are consistent with a biological, and not an indirect chemical, reduction of manganese, which suggest that this bacterium uses manganic oxide as a terminal electron acceptor. It can also utilize a large number of other compounds as terminal electron acceptors; this versatility could provide a distinct advantage in environments where electron-acceptor concentrations may vary.

  6. Effect of enhanced manganese oxidation in the hyporheic zone on basin-scale geochemical mass balance

    NASA Astrophysics Data System (ADS)

    Harvey, Judson W.; Fuller, Christopher C.

    1998-04-01

    We determined the role of the hyporheic zone (the subsurface zone where stream water and shallow groundwater mix) in enhancing microbially mediated oxidation of dissolved manganese (to form manganese precipitates) in a drainage basin contaminated by copper mining. The fate of manganese is of overall importance to water quality in Pinal Creek Basin, Arizona, because manganese reactions affect the transport of trace metals. The basin-scale role of the hyporheic zone is difficult to quantify because stream-tracer studies do not always reliably characterize the cumulative effects of the hyporheic zone. This study determined cumulative effects of hyporheic reactions in Pinal Creek basin by characterizing manganese uptake at several spatial scales (stream-reach scale, hyporheic-flow-path scale, and sediment-grain scale). At the stream-reach scale a one-dimensional stream-transport model (including storage zones to represent hyporheic flow paths) was used to determine a reach-averaged time constant for manganese uptake in hyporheic zones, 1/λs, of 1.3 hours, which was somewhat faster but still similar to manganese uptake time constants that were measured directly in centimeter-scale hyporheic flow paths (1/λh = 2.6 hours), and in laboratory batch experiments using streambed sediment (1/λ = 2.7 hours). The modeled depths of subsurface storage zones (ds = 4-17 cm) and modeled residence times of water in storage zones (ts = 3-12 min) were both consistent with direct measurements in hyporheic flow paths (dh = 0-15 cm, th = 1-25 min). There was also good agreement between reach-scale modeling and direct measurements of the percentage removal of dissolved manganese in hyporheic flow paths (fs = 8.9%, andfh = 9.3%rpar;. Manganese uptake experiments in the laboratory using sediment from Pinal Creek demonstrated (through comparison of poisoned and unpoisoned treatments) that the manganese removal process was enhanced by microbially mediated oxidation. The cumulative effect of

  7. Effect of enhanced manganese oxidation in the hyporheic zone on basin-scale geochemical mass balance

    USGS Publications Warehouse

    Harvey, J.W.; Fuller, C.C.

    1998-01-01

    We determined the role of the hyporheic zone (the subsurface zone where stream water and shallow groundwater mix) in enhancing microbially mediated oxidation of dissolved manganese (to form manganese precipitates) in a drainage basin contaminated by copper mining. The fate of manganese is of overall importance to water quality in Pinal Creek Basin, Arizona, because manganese reactions affect the transport of trace metals. The basin-scale role of the hyporheic zone is difficult to quantify because stream-tracer studies do not always reliably characterize the cumulative effects of the hyporheic zone. This study determined cumulative effects of hyporheic reactions in Pinal Creek basin by characterizing manganese uptake at several spatial scales (stream-reach scale, hyporheicflow-path scale, and sediment-grain scale). At the stream-reach scale a one-dimensional stream-transport model (including storage zones to represent hyporheic flow paths) was used to determine a reach-averaged time constant for manganese uptake in hyporheic zones, 1/??(s), of 1.3 hours, which was somewhat faster but still similar to manganese uptake time constants that were measured directly in centimeter-scale hyporheic flow paths (1/??(h) = 2.6 hours), and in laboratory batch experiments using streambed sediment (1/?? = 2.7 hours). The modeled depths of subsurface storage zones (d(s) = 4-17 cm) and modeled residence times of water in storage zones (t(s) = 3-12 min) were both consistent with direct measurements in hyporheic flow paths (d(h) = 0-15 cm, and t(h) = 1-25 min). There was also good agreement between reach-scale modeling and direct measurements of the percentage removal of dissolved manganese in hyporheic flow paths (f(s) = 8.9%, and f(h) = 9.3%). Manganese uptake experiments in the laboratory using sediment from Pinal Creek demonstrated (through comparison of poisoned and unpoisoned treatments) that the manganese removal process was enhanced by microbially mediated oxidation. The

  8. Metal Uptake by Manganese Superoxide Dismutase

    PubMed Central

    Whittaker, James W.

    2009-01-01

    Manganese superoxide dismutase is an important antioxidant defense metalloenzyme that protects cells from damage by the toxic oxygen metabolite, superoxide free radical, formed as an unavoidable by-product of aerobic metabolism. Many years of research have gone into understanding how the metal cofactor interacts with small molecules in its catalytic role. In contrast, very little is presently known about how the protein acquires its metal cofactor, an important step in the maturation of the protein and one that is absolutely required for its biological function. Recent work is beginning to provide insight into the mechanisms of metal delivery to manganese superoxide dismutase in vivo and in vitro. PMID:19699328

  9. A zinc-resistant human epithelial cell line is impaired in cadmium and manganese import

    SciTech Connect

    Rousselet, Estelle |; Richaud, Pierre ||; Douki, Thierry; Chantegrel, Jocelyne Garcia; Favier, Alain |||; Moulis, Jean-Marc ||

    2008-08-01

    A human epithelial cell line (HZR) growing with high zinc concentrations has been analyzed for its ability to sustain high cadmium concentrations. Exposure to up to 200 {mu}M of cadmium acetate for 24 h hardly impacted viability, whereas most of parental HeLa cells were killed by less than 10 {mu}M of cadmium. Upon challenge by 35 fold higher cadmium concentrations than HeLa cells, HZR cells did not display increased DNA damage, increased protein oxidation, or changed intracellular cadmium localization. Rather, the main cause of resistance against cadmium was by avoiding cadmium entry into cells, which differs from that against zinc as the latter accumulates inside cells. The zinc-resistant phenotype of these cells was shown to also impair extracellular manganese uptake. Manganese and cadmium competed for entry into HeLa cells. Probing formerly identified cadmium or manganese transport systems in different animal cells did not evidence any significant change between HeLa and HZR cells. These results reveal zinc adaptation influences manganese and cadmium cellular traffic and they highlight previously unknown connections among homeostasis of divalent metals.

  10. Role of Manganese Deposition on Graphite in the Capacity Fading of Lithium Ion Batteries.

    PubMed

    Vissers, Daniel R; Chen, Zonghai; Shao, Yuyan; Engelhard, Mark; Das, Ujjal; Redfern, Paul; Curtiss, Larry A; Pan, Baofei; Liu, Jun; Amine, Khalil

    2016-06-01

    Lithium ion batteries utilizing manganese-based cathodes have received considerable interest in recent years for their lower cost and more favorable environmental friendliness relative to their cobalt counterparts. However, Li ion batteries using these cathodes combined with graphite anodes suffer from severe capacity fading at high operating temperatures. In this paper, we report on how the dissolution of manganese impacts the capacity fading within the Li ion batteries. Our investigation reveals that the manganese dissolves from the cathode, transports to the graphite electrode, and deposits onto the outer surface of the innermost solid-electrolyte interphase layer, which is known to be a mixture of inorganic salts (e.g., Li2CO3, LiF, and Li2O). In this location, the manganese facilitates the reduction of the electrolyte and the subsequent formation of lithium-containing products on the graphite, which removes lithium ions from the normal operation of the cell and thereby induces the severe capacity fade. PMID:27152912

  11. Studies of C-Axis Charge Transport in BISMUTH(2) STRONTIUM(2) Calcium COPPER(2) OXYGEN(8 + Delta) and Anomalous Hall Effect in (LANTHANUM(0.67) CALCIUM(0.33)) Manganese OXYGEN(3)

    NASA Astrophysics Data System (ADS)

    Yi-Feng, Yan

    In this thesis I report my studies on charge transport on two perovskite metal oxides: La_ {1-x}Ca_{x}MnO_3(LCMO) --a colossal magnetoresistance oxide and Bi_2Sr_2CaCu_2O_{8+delta } (BSCCO)--a high temperature superconducting compound. Large and high quality Bi_2Sr _2CaCu_2O_{8+delta} single crystals were grown by self-flux method. The quality of the crystals were examined by x-ray diffraction and electron diffraction. I have systematically investigated the c-axis magnetoresistance (MR) of various BSCCO single crystals with different oxygen contents. With field H parallel to c-axis and the current (H//c//J), we observed that MR is negative if rho_ {c} is semiconducting and positive if rho_{c} is pseudo-metallic. We consider that the negative MR is a normal state property. We have also measured the field dependence of rho_{c} in the flux flow state (H//c//J) at fields up to 14T. Whereas rho_{c} increases rapidly in weak fields, it saturates to the extrapolated normal-state curve when the field H_ {2D} is attained (H_ {2D} is the field at which the vortex pancakes in adjacent layers are completely decoupled). At fields above H_{2D}, rho_{c} decreases slowly. We verify that this is a continuation of the negative MR observed above Tc. We propose that the antiferromagnetic coupling along the c-axis in adjacent CuO_2 planes and spin singlet formation are the cause of negative magnetoresistance in c-axis in bilayer cuprates. We found that the c-axis resistivity in bilayer cuprates can be fitted into the following empirical formula: rho_{c}{= }a/Te^{Delta/T} + cT + d where a, c and d are temperature independent constants; Delta is called pseudogap. In Y -doped BSCCO, rho_{c} displays a logarithmic temperature dependence. The LCMO thin films used in this experiment were grown by Plasma Enhanced-MOCVD method. The Hall effect and magnetoresistance of LCMO thin films have been systematically investigated. At low temperature, the Hall effect is linear with field and positive

  12. Manganese regulation of manganese peroxidase expression and lignin degradation by the white rot fungus Dichomitus squalens

    SciTech Connect

    Perie, F.; Gold, M.H. )

    1991-08-01

    Extracellular manganese peroxidase and laccase activities were detected in cultures of Dichomitus squalens (Polyporus anceps) under conditions favoring lignin degradation. In contrast, neither extracellular lignin peroxidase nor aryl alcohol oxidase activity was detected in cultures grown under a wide variety of conditions. The mineralization of {sup 14}C-ring-, -side chain-, and -methoxy-labeled synthetic guaiacyl lignins by D. squalens and the expression of extracellular manganese peroxidase were dependent on the presence of Mn(II), suggesting that manganese peroxidase is an important component of this organism's lignin degradation system. The expression of laccase activity was independent of manganese. In contrast to previous findings with Phanero-chaete chrysosporium, lignin degradation by D. squalens proceeded in the cultures containing excess carbon and nitrogen.

  13. Importance of vegetation for manganese cycling in temperate forested watersheds

    NASA Astrophysics Data System (ADS)

    Herndon, Elizabeth M.; Jin, Lixin; Andrews, Danielle M.; Eissenstat, David M.; Brantley, Susan L.

    2015-02-01

    Many surface soils are enriched in metals due to anthropogenic atmospheric inputs. To predict the persistence of these contaminants in soils, factors that impact rates of metal removal from soils into streams must be understood. Experiments at containerized seedling (mesocosm), pedon, and catchment scales were used to investigate the influence of vegetation on manganese (Mn) transport at the Susquehanna/Shale Hills Critical Zone Observatory (SSHCZO) in Pennsylvania, USA, where past atmospheric inputs from industrial sources have enriched Mn in surface soils. Large quantities of Mn that were leached from soil components into solution were taken up by vegetation; as a result, only relatively small quantities of Mn were removed from soil into effluent and streams. Manganese uptake into vegetation exceeded Mn losses in soil leachate by 20-200X at all scales, and net Mn loss from soils decreased in the presence of vegetation due to uptake into plant tissues. The majority of Mn taken up by forest vegetation at SSHCZO each year was returned to the soil in leaf litter and consequently immobilized as Mn oxides that formed during litter decomposition. Thus, plant uptake of Mn combined with rapid oxidation of Mn during litter decomposition contribute to long-term retention. Current release rates of soluble Mn from SSHCZO soils were similar to release rates from the larger Susquehanna River Basin, indicating that the processes observed at SSHCZO may be widespread across the region. Indeed, although atmospheric deposition of Mn has declined, surface soils at SSHCZO and throughout the eastern United States remain enriched in Mn. If recycling through vegetation can attenuate the removal of Mn from soils, as observed in this study, then Mn concentrations in soils and river waters will likely decrease slowly over time following watershed contamination. Understanding the role of vegetation in regulating metal transport is important for evaluating the long-term effects of historical

  14. Manganese ore tailing: optimization of acid leaching conditions and recovery of soluble manganese.

    PubMed

    Santos, Olívia de Souza Heleno; Carvalho, Cornélio de Freitas; Silva, Gilmare Antônia da; Santos, Cláudio Gouvêa Dos

    2015-01-01

    Manganese recovery from industrial ore processing waste by means of leaching with sulfuric acid was the objective of this study. Experimental conditions were optimized by multivariate experimental design approaches. In order to study the factors affecting leaching, a screening step was used involving a full factorial design with central point for three variables in two levels (2(3)). The three variables studied were leaching time, concentration of sulfuric acid and sample amount. The three factors screened were shown to be relevant and therefore a Doehlert design was applied to determine the best working conditions for leaching and to build the response surface. By applying the best leaching conditions, the concentrations of 12.80 and 13.64 %w/w of manganese for the global sample and for the fraction -44 + 37 μm, respectively, were found. Microbeads of chitosan were tested for removal of leachate acidity and recovering of soluble manganese. Manganese recovery from the leachate was 95.4%. Upon drying the leachate, a solid containing mostly manganese sulfate was obtained, showing that the proposed optimized method is efficient for manganese recovery from ore tailings. PMID:25284800

  15. 21 CFR 184.1446 - Manganese chloride.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Manganese chloride. 184.1446 Section 184.1446 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) DIRECT FOOD SUBSTANCES AFFIRMED AS GENERALLY RECOGNIZED AS SAFE Listing of Specific Substances Affirmed as GRAS...

  16. 21 CFR 582.5455 - Manganese glycerophosphate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Manganese glycerophosphate. 582.5455 Section 582.5455 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5455...

  17. 21 CFR 582.5458 - Manganese hypophosphite.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Manganese hypophosphite. 582.5458 Section 582.5458 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5458...

  18. Geology of the manganese deposits of Cuba

    USGS Publications Warehouse

    Simons, Frank S.; Straczek, John A.

    1958-01-01

    Deposits of manganese ore have been found in five of the six provinces of Cuba and have been reported from the sixth.  Only Oriente and Pinar del Rio provinces have more than a few known deposits and only the deposits of Oriente have yielded any appreciable amount of ore.

  19. The Products of Manganese (II) Oxidation

    SciTech Connect

    Perkins, A.

    2004-09-03

    Manganese, the second most abundant transition metal in the earth's crust, exists in a number of oxidation states, among which the II, III, and IV oxidation states are of greatest environmental importance. Produced through microbial activity, manganese oxides help to mediate redox reactions with organic and inorganic compounds and help to sequester a variety of metals. The mechanism by which Manganese (II) is oxidized to Manganese (IV) is a biologically catalyzed process. There are at least three different pathways by which Mn(II) can be bacterially oxidized to Mn(IV); the first in which states that Mn(II) can be oxidized to mixed Mn(III, IV), and Mn(IV) oxides and oxyhydroxides. The second of these pathways is that Mn(II) can be directly oxidized to Mn(IV) and the last of these pathways is that Mn(II) follows an enzymatic bond with a Mn(III) intermediate in which Mn(II) oxidizes to Mn(III) and then to Mn(IV). The pathways of focus for this research are the latter two pathways.

  20. Lithium Manganese Silicate Positive Electrode Material

    NASA Astrophysics Data System (ADS)

    Yang, Qiong

    As the fast development of the electronic portable devices and drastic fading of fossil energy sources. The need for portable secondary energy sources is increasingly urgent. As a result, lithium ion batteries are being investigated intensely to meet the performance requirements. Among various electrode materials, the most expensive and capacity limiting component is the positive materials. Based on this, researches have been mostly focused on the development of novel cathode materials with high capacity and energy density and the lithium transition metal orthosilicates have been identified as possible high performance cathodes. Here in, we report the synthesis of a kind of lithium transition metal orthosilicates electrode lithium manganese silicate. Lithium manganese silicate has the advantage of high theoretical capacity, low cost raw material and safety. In this thesis, lithium manganese silicate are prepared using different silicon sources. The structure of silicon sources preferred are examined. Nonionic block copolymers surfactant, P123, is tried as carbon source and mophology directing agent. Lithium manganese silicate's performances are improved by adding P123.

  1. ADVERSE HEALTH EFFECTS FROM ENVIRONMENTAL MANGANESE EXPOSURE.

    EPA Science Inventory

    The ubiquitous element, manganese (Mn), is an essential nutrient, but toxic at excessive exposure levels. Therefore, the US EPA set guideline levels for Mn exposure through inhalation (reference concentration-RfC=0.05 ?g/m3) and ingestion (reference dose-RfD=0.14 mg/kg/day (10 mg...

  2. 21 CFR 582.5446 - Manganese chloride.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Manganese chloride. 582.5446 Section 582.5446 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or...

  3. 21 CFR 184.1446 - Manganese chloride.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ..., and crystallized. (b) The ingredient meets the specifications of the Food Chemicals Codex, 3d Ed... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Manganese chloride. 184.1446 Section 184.1446 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD...

  4. Soil Manganese Enrichment from Industrial Inputs: A Gastropod Perspective

    PubMed Central

    Bordean, Despina-Maria; Nica, Dragos V.; Harmanescu, Monica; Banatean-Dunea, Ionut; Gergen, Iosif I.

    2014-01-01

    Manganese is one of the most abundant metal in natural environments and serves as an essential microelement for all living systems. However, the enrichment of soil with manganese resulting from industrial inputs may threaten terrestrial ecosystems. Several studies have demonstrated harmful effects of manganese exposure by cutaneous contact and/or by soil ingestion to a wide range of soil invertebrates. The link between soil manganese and land snails has never been made although these invertebrates routinely come in contact with the upper soil horizons through cutaneous contact, egg-laying, and feeding activities in soil. Therefore, we have investigated the direct transfer of manganese from soils to snails and assessed its toxicity at background concentrations in the soil. Juvenile Cantareus aspersus snails were caged under semi-field conditions and exposed first, for a period of 30 days, to a series of soil manganese concentrations, and then, for a second period of 30 days, to soils with higher manganese concentrations. Manganese levels were measured in the snail hepatopancreas, foot, and shell. The snail survival and shell growth were used to assess the lethal and sublethal effects of manganese exposure. The transfer of manganese from soil to snails occurred independently of food ingestion, but had no consistent effect on either the snail survival or shell growth. The hepatopancreas was the best biomarker of manganese exposure, whereas the shell did not serve as a long-term sink for this metal. The kinetics of manganese retention in the hepatopancreas of snails previously exposed to manganese-spiked soils was significantly influenced by a new exposure event. The results of this study reveal the importance of land snails for manganese cycling in terrestrial biotopes and suggest that the direct transfer from soils to snails should be considered when precisely assessing the impact of anthropogenic Mn releases on soil ecosystems. PMID:24454856

  5. Suppression of oxidative damage by Saccharomyces cerevisiae ATX2, which encodes a manganese-trafficking protein that localizes to Golgi-like vesicles.

    PubMed Central

    Lin, S J; Culotta, V C

    1996-01-01

    Oxygen toxicity in Saccharomyces cerevisiae lacking the copper/zinc superoxide dismutase (SOD1) can be suppressed by overexpression of the S. cerevisiae ATX2 gene. Multiple copies of ATX2 were found to reverse the aerobic auxotrophies of sod1(delta) mutants for lysine and methionine and also to enhance the resistance of these yeast strains to paraquat and atmospheric levels of oxygen. ATX2 encodes a novel 34.4-kDa polypeptide with a number of potential membrane-spanning domains. Our studies indicate that Atx2p localizes to the membrane of a vesicular compartment in yeast cells reminiscent of the Golgi apparatus. With indirect immunofluorescence microscopy, Atx2p exhibited a punctate pattern of staining typical of the Golgi apparatus, and upon subcellular fractionation, Atx2p colocalized with a biochemical marker for the yeast Golgi apparatus. We demonstrate here that this vesicle protein normally functions in the homeostasis of manganese ions and that this role in metal metabolism is necessary for the ATX1 suppression of SOD1 deficiency. First, overexpression of ATX2 caused cells to accumulate increased levels of manganese. Second, a deletion in ATX2 caused a decrease in the apparent available level of intracellular manganese and caused sod1(delta) mutants to become dependent upon exogenous manganese for aerobic growth. Third, ATX2 was incapable of suppressing oxidative damage in cells depleted of manganese ions or lacking the plasma membrane transporter for manganese. The effect of ATX2 overexpression on manganese accumulation and oxygen resistance is similar to what we have previously reported for mutations in PMR1, which encodes a manganese-trafficking protein that also resides in a vesicular compartment. Our studies are consistent with a model in which Atx2p and Pmr1p work in opposite directions to control manganese homeostasis. PMID:8887660

  6. Restoration of growth by manganese in a mutant strain of Escherichia coli lacking most known iron and manganese uptake systems.

    PubMed

    Taudte, Nadine; German, Nadezhda; Zhu, Yong-Guan; Grass, Gregor; Rensing, Christopher

    2016-06-01

    The interplay of manganese and iron homeostasis and oxidative stress in Escherichia coli can give important insights into survival of bacteria in the phagosome and under differing iron or manganese bioavailabilities. Here, we characterized a mutant strain devoid of all know iron/manganese-uptake systems relevant for growth in defined medium. Based on these results an exit strategy enabling the cell to cope with iron depletion and use of manganese as an alternative for iron could be shown. Such a strategy would also explain why E. coli harbors some iron- or manganese-dependent iso-enzymes such as superoxide dismutases or ribonucleotide reductases. The benefits for gaining a means for survival would be bought with the cost of less efficient metabolism as indicated in our experiments by lower cell densities with manganese than with iron. In addition, this strain was extremely sensitive to the metalloid gallium but this gallium toxicity can be alleviated by low concentrations of manganese. PMID:27003826

  7. The influence of high iron diet on rat lung manganese absorption

    SciTech Connect

    Thompson, Khristy; Molina, Ramon; Donaghey, Thomas; Brain, Joseph D.; Wessling-Resnick, Marianne . E-mail: wessling@hsph.harvard.edu

    2006-01-15

    Individuals chronically exposed to manganese are at high risk for neurotoxic effects of this metal. A primary route of exposure is through respiration, although little is known about pulmonary uptake of metals or factors that modify this process. High dietary iron levels inversely affect intestinal uptake of manganese, and a major goal of this study was to determine if dietary iron loading could increase lung non-heme iron levels and alter manganese absorption. Rats were fed a high iron (1% carbonyl iron) or control diet for 4 weeks. Lung non-heme iron levels increased {approx}2-fold in rats fed the high iron diet. To determine if iron-loading affected manganese uptake, {sup 54}Mn was administered by intratracheal (it) instillation or intravenous (iv) injection for pharmacokinetic studies. {sup 54}Mn absorption from the lungs to the blood was lower in it-instilled rats fed the 1% carbonyl iron diet. Pharmacokinetics of iv-injected {sup 54}Mn revealed that the isotope was cleared more rapidly from the blood of iron-loaded rats. In situ analysis of divalent metal transporter-1 (DMT1) expression in lung detected mRNA in airway epithelium and bronchus-associated lymphatic tissue (BALT). Staining of the latter was significantly reduced in rats fed the high iron diet. In situ analysis of transferrin receptor (TfR) mRNA showed staining in BALT alone. These data demonstrate that manganese absorption from the lungs to the blood can be modified by iron status and the route of administration.

  8. A simple route to synthesize manganese germanate nanorods

    SciTech Connect

    Pei, L.Z. Yang, Y.; Yuan, C.Z.; Duan Taike; Zhang Qianfeng

    2011-06-15

    Manganese germanate nanorods have been synthesized by a simple route using germanium dioxide and manganese acetate as the source materials. X-ray diffraction observation shows that the nanorods are composed of orthorhombic and monoclinic manganese germanate phases. Scanning electron microscopy and transmission electron microscopy observations display that the manganese germanate nanorods have flat tips with the length of longer than 10 micrometers and diameter of 60-350 nm, respectively. The role of the growth conditions on the formation of the manganese germanate nanorods shows that the proper selection and combination of the growth conditions are the key factor for controlling the formation of the manganese germanate nanorods. The photoluminescence spectrum of the manganese germanate nanorods exhibits four fluorescence emission peaks centered at 422 nm, 472 nm, 487 nm and 530 nm showing the application potential for the optical devices. - Research Highlights: {yields} Manganese germanate nanorods have been synthesized by simple hydrothermal process. {yields} The formation of manganese germanate nanorods can be controlled by growth conditions. {yields} Manganese germanate nanorods exhibit good PL emission ability for optical device.

  9. Manganese oxide cathodes for rechargeable batteries

    NASA Astrophysics Data System (ADS)

    Im, Dongmin

    Manganese oxides are considered as promising cathodes for rechargeable batteries due to their low cost and low toxicity as well as the abundant natural resources. In this dissertation, manganese oxides have been investigated as cathodes for both rechargeable lithium and alkaline batteries. Nanostructured lithium manganese oxides designed for rechargeable lithium cells have been synthesized by reducing lithium permanganate with methanol or hydrogen in various solvents followed by firing at moderate temperatures. The samples have been characterized by wet-chemical analyses, thermal methods, spectroscopic methods, and electron microscopy. It has been found that chemical residues in the oxides such as carboxylates and hydroxyl groups, which could be controlled by varying the reaction medium, reducing agents, and additives, make a significant influence on the electrochemical properties. The Li/Mn ratio in the material has also been found to be a critical factor in determining the rechargeability of the cathodes. The optimized samples exhibit a high capacity of close to 300 mAh/g with good cyclability and charge efficiency. The high capacity with a lower discharge voltage may make these nanostructured oxides particularly attractive for lithium polymer batteries. The research on the manganese oxide cathodes for alkaline batteries is focused on an analysis of the reaction products generated during the charge/discharge processes or by some designed chemical reactions mimicking the electrochemical processes. The factors influencing the formation of Mn3O4 in the two-electron redox process of delta-MnO2 have been studied with linear sweep voltammetry combined with X-ray diffraction. The presence of bismuth, the discharge rate, and the microstructure of the electrodes are found to affect the formation of Mn3O4, which is known to be electrochemically inactive. A faster voltage sweep and a more intimate mixing of the manganese oxide and carbon in the cathode are found to suppress

  10. Preparation of manganese sulfate from low-grade manganese carbonate ores by sulfuric acid leaching

    NASA Astrophysics Data System (ADS)

    Lin, Qing-quan; Gu, Guo-hua; Wang, Hui; Zhu, Ren-feng; Liu, You-cai; Fu, Jian-gang

    2016-05-01

    In this study, a method for preparing pure manganese sulfate from low-grade ores with a granule mean size of 0.47 mm by direct acid leaching was developed. The effects of the types of leaching agents, sulfuric acid concentration, reaction temperature, and agitation rate on the leaching efficiency of manganese were investigated. We observed that sulfuric acid used as a leaching agent provides a similar leaching efficiency of manganese and superior selectivity against calcium compared to hydrochloric acid. The optimal leaching conditions in sulfuric acid media were determined; under the optimal conditions, the leaching efficiencies of Mn and Ca were 92.42% and 9.61%, respectively. Moreover, the kinetics of manganese leaching indicated that the leaching follows the diffusion-controlled model with an apparent activation energy of 12.28 kJ·mol-1. The purification conditions of the leaching solution were also discussed. The results show that manganese dioxide is a suitable oxidant of ferrous ions and sodium dimethyldithiocarbamate is an effective precipitant of heavy metals. Finally, through chemical analysis and X-ray diffraction analysis, the obtained product was determined to contain 98% of MnSO4·H2O.

  11. Ferroportin deficiency impairs manganese metabolism in flatiron mice

    PubMed Central

    Seo, Young Ah; Wessling-Resnick, Marianne

    2015-01-01

    We examined the physiologic role of ferroportin (Fpn) in manganese (Mn) export using flatiron (ffe/+) mice, a genetic model of Fpn deficiency. Blood (0.0123 vs. 0.0107 mg/kg; P = 0.0003), hepatic (1.06 vs. 0.96 mg/kg; P = 0.0125), and bile Mn levels (79 vs. 38 mg/kg; P = 0.0204) were reduced in ffe/+ mice compared to +/+ controls. Erythrocyte Mn–superoxide dismutase was also reduced at 6 (0.154 vs. 0.096, P = 0.0101), 9 (0.131 vs. 0.089, P = 0.0162), and 16 weeks of age (0.170 vs. 0.090 units/mg protein/min; P < 0.0001). 54Mn uptake after intragastric gavage was markedly reduced in ffe/+ mice (0.0187 vs. 0.0066% dose; P = 0.0243), while clearance of injected isotope was similar in ffe/+ and +/+ mice. These values were compared to intestinal absorption of 59Fe, which was significantly reduced in ffe/+ mice (8.751 vs. 3.978% dose; P = 0.0458). The influence of the ffe mutation was examined in dopaminergic SH-SY5Y cells and human embryonic HEK293T cells. While expression of wild-type Fpn reversed Mn-induced cytotoxicity, ffe mutant H32R failed to confer protection. These combined results demonstrate that Fpn plays a central role in Mn transport and that flatiron mice provide an excellent genetic model to explore the role of this exporter in Mn homeostasis.—Seo, Y. A., Wessling-Resnick, M. Ferroportin deficiency impairs manganese metabolism in flatiron mice. PMID:25782988

  12. Development of an accelerator based system for in vivo neutron activation analysis measurements of manganese in humans

    NASA Astrophysics Data System (ADS)

    Arnold, Michelle Lynn

    2001-11-01

    reaction, used to produce neutrons by the KN, were conducted to determine neutron spectral information, angular distributions and yields. These data were used as input for the transport code MCNP, and computer simulations of experimental conditions were performed. The simulations consistently overestimate experiment measurements by a constant factor, and possible reasons for this discrepancy are discussed. It has been concluded that IVNAA measurements of the brain would only provide limited information, however, measurement of both the liver and hand bone should be possible. It is recommended that preliminary in vivo measurements be pursued for the hand, as metabolic data suggest that bone may be a long term storage site for manganese.

  13. Importance of effective dimensionality in manganese pnictides

    NASA Astrophysics Data System (ADS)

    Zingl, Manuel; Assmann, Elias; Seth, Priyanka; Krivenko, Igor; Aichhorn, Markus

    2016-07-01

    In this paper we investigate the two manganese pnictides BaMn2As2 and LaMnAsO, using fully charge self-consistent density functional plus dynamical mean-field theory calculations. These systems have a nominally half-filled d shell, and as a consequence, electronic correlations are strong, placing these compounds at the verge of a metal-insulator transition. Although their crystal structure is composed of similar building blocks, our analysis shows that the two materials exhibit a very different effective dimensionality, LaMnAsO being a quasi-two-dimensional material in contrast to the much more three-dimensional BaMn2As2 . We demonstrate that the experimentally observed differences in the Néel temperature, the band gap, and the optical properties of the manganese compounds under consideration can be traced back to exactly this effective dimensionality. Our calculations show excellent agreement with measured optical spectra.

  14. Dietary manganese requirement of P. Vannamei

    NASA Astrophysics Data System (ADS)

    Liu, Fa-Yi; Lawrence, A. L.

    1997-06-01

    Graded levels of manganese were supplemented to a semi-purified diet containing 45% crude protein, to provide six levels of manganese (i. e. containing 5, 25, 50, 70, 140 and 210×10-6, respectively) for two experiments with these experimental diets. The initial weight of shrimp used in the 35 day experiment I was 0.30±0.04 g, and that in the 70 day Experiment II was more than one gram. The results showed that optimum content in the semi-purified diet for the more than 1 gram shrimp ranged from 70 ×10-6, to 140×10-6, but supplementation of Mn was not necessary for the small shrimp.

  15. Biomimetic Water-Oxidation Catalysts: Manganese Oxides.

    PubMed

    Kurz, Philipp

    2016-01-01

    The catalytic oxidation of water to molecular oxygen is a key process for the production of solar fuels. Inspired by the biological manganese-based active site for this reaction in the enzyme Photosystem II, researchers have made impressive progress in the last decades regarding the development of synthetic manganese catalysts for water oxidation. For this, it has been especially fruitful to explore the many different types of known manganese oxides MnOx. This chapter first offers an overview of the structural, thermodynamic, and mechanistic aspects of water-oxidation catalysis by MnOx. The different test systems used for catalytic studies are then presented together with general reactivity trends. As a result, it has been possible to identify layered, mixed Mn (III/IV)-oxides as an especially promising class of bio-inspired catalysts and an attempt is made to give structure-based reasons for the good performances of these materials. In the outlook, the challenges of catalyst screenings (and hence the identification of a "best MnOx catalyst") are discussed. There is a great variety of reaction conditions which might be relevant for the application of manganese oxide catalysts in technological solar fuel-producing devices, and thus catalyst improvements are currently still addressing a very large parameter space. Nonetheless, detailed knowledge about the biological catalyst and a solid experimental basis concerning the syntheses and water-oxidation reactivities of MnOx materials have been established in the last decade and thus this research field is well positioned to make important contributions to solar fuel research in the future. PMID:25980320

  16. Manganese redistribution by calcium-stimulated vesicle trafficking bypasses the need for P-type ATPase function.

    PubMed

    García-Rodríguez, Néstor; Manzano-López, Javier; Muñoz-Bravo, Miguel; Fernández-García, Elisabet; Muñiz, Manuel; Wellinger, Ralf Erik

    2015-04-10

    Regulation of intracellular ion homeostasis is essential for eukaryotic cell physiology. An example is provided by loss of ATP2C1 function, which leads to skin ulceration, improper keratinocyte adhesion, and cancer formation in Hailey-Hailey patients. The yeast ATP2C1 orthologue PMR1 codes for a Mn(2+)/Ca(2+) transporter that is crucial for cis-Golgi manganese supply. Here, we present evidence that calcium overcomes the lack of Pmr1 through vesicle trafficking-stimulated manganese delivery and requires the endoplasmic reticulum Mn(2+) transporter Spf1 and the late endosome/trans-Golgi Nramp metal transporter Smf2. Smf2 co-localizes with the putative Mn(2+) transporter Atx2, and ATX2 overexpression counteracts the beneficial impact of calcium treatment. Our findings suggest that vesicle trafficking promotes organelle-specific ion interchange and cytoplasmic metal detoxification independent of calcineurin signaling or metal transporter re-localization. Our study identifies an alternative mode for cis-Golgi manganese supply in yeast and provides new perspectives for Hailey-Hailey disease treatment. PMID:25713143

  17. Manganese Redistribution by Calcium-stimulated Vesicle Trafficking Bypasses the Need for P-type ATPase Function*

    PubMed Central

    García-Rodríguez, Néstor; Manzano-López, Javier; Muñoz-Bravo, Miguel; Fernández-García, Elisabet; Muñiz, Manuel; Wellinger, Ralf Erik

    2015-01-01

    Regulation of intracellular ion homeostasis is essential for eukaryotic cell physiology. An example is provided by loss of ATP2C1 function, which leads to skin ulceration, improper keratinocyte adhesion, and cancer formation in Hailey-Hailey patients. The yeast ATP2C1 orthologue PMR1 codes for a Mn2+/Ca2+ transporter that is crucial for cis-Golgi manganese supply. Here, we present evidence that calcium overcomes the lack of Pmr1 through vesicle trafficking-stimulated manganese delivery and requires the endoplasmic reticulum Mn2+ transporter Spf1 and the late endosome/trans-Golgi Nramp metal transporter Smf2. Smf2 co-localizes with the putative Mn2+ transporter Atx2, and ATX2 overexpression counteracts the beneficial impact of calcium treatment. Our findings suggest that vesicle trafficking promotes organelle-specific ion interchange and cytoplasmic metal detoxification independent of calcineurin signaling or metal transporter re-localization. Our study identifies an alternative mode for cis-Golgi manganese supply in yeast and provides new perspectives for Hailey-Hailey disease treatment. PMID:25713143

  18. Manganese oxide nanowires, films, and membranes and methods of making

    SciTech Connect

    Suib, Steven Lawrence; Yuan, Jikang

    2011-02-15

    Nanowires, films, and membranes comprising ordered porous manganese oxide-based octahedral molecular sieves and methods of making the same are disclosed. A method for forming nanowires includes hydrothermally treating a chemical precursor composition in a hydrothermal treating solvent to form the nanowires, wherein the chemical precursor composition comprises a source of manganese cations and a source of counter cations, and wherein the nanowires comprise ordered porous manganese oxide-based octahedral molecular sieves.

  19. Manganese deposition in drinking water distribution systems.

    PubMed

    Gerke, Tammie L; Little, Brenda J; Barry Maynard, J

    2016-01-15

    This study provides a physicochemical assessment of manganese deposits on brass and lead components from two fully operational drinking water distributions systems. One of the systems was maintained with chlorine; the other, with secondary chloramine disinfection. Synchrotron-based in-situ micro X-ray adsorption near edge structure was used to assess the mineralogy. In-situ micro X-ray fluorescence mapping was used to demonstrate the spatial relationships between manganese and potentially toxic adsorbed metal ions. The Mn deposits ranged in thickness from 0.01 to 400 μm. They were composed primarily of Mn oxides/oxhydroxides, birnessite (Mn(3+) and Mn(4+)) and hollandite (Mn(2+) and Mn(4+)), and a Mn silicate, braunite (Mn(2+) and Mn(4+)), in varying proportions. Iron, chromium, and strontium, in addition to the alloying elements lead and copper, were co-located within manganese deposits. With the exception of iron, all are related to specific health issues and are of concern to the U.S. Environmental Protection Agency (U.S. EPA). The specific properties of Mn deposits, i.e., adsorption of metals ions, oxidation of metal ions and resuspension are discussed with respect to their influence on drinking water quality. PMID:26409148

  20. Deposition of manganese in a drinking water distribution system.

    PubMed Central

    Sly, L I; Hodgkinson, M C; Arunpairojana, V

    1990-01-01

    The deposition of manganese in a water distribution system with manganese-related "dirty water" problems was studied over a 1-year period. Four monitoring laboratories with Robbins biofilm sampling devices fitted to the water mains were used to correlate the relationship among manganese deposition, the level of manganese in the water, and the chlorination conditions. Manganese deposition occurred by both chemical and microbial processes. Chemical deposition occurred when Mn(II) not removed during water treatment penetrated the filters and entered the distribution system, where it was oxidized by chlorine and chlorine dioxide used for disinfection. Microbial deposition occurred in areas with insufficient chlorination to control the growth of manganese-depositing biofilm. At 0.05 mg of Mn(II) per liter, the chemical deposition rate was much greater than microbial deposition. Significant deposition occurred at 0.03 mg of manganese per liter, and dirty water complaints were not eliminated until manganese levels were continuously less than 0.02 mg/liter and chlorination levels were greater than 0.2 mg/liter. A guideline level of 0.01 mg of manganese per liter is recommended. Images PMID:2317040

  1. Manganese-enhanced magnetic resonance microscopy of mineralization

    USGS Publications Warehouse

    Chesnick, I.E.; Todorov, T.I.; Centeno, J.A.; Newbury, D.E.; Small, J.A.; Potter, K.

    2007-01-01

    Paramagnetic manganese (II) can be employed as a calcium surrogate to sensitize magnetic resonance microscopy (MRM) to the processing of calcium during bone formation. At high doses, osteoblasts can take up sufficient quantities of manganese, resulting in marked changes in water proton T1, T2 and magnetization transfer ratio values compared to those for untreated cells. Accordingly, inductively coupled plasma mass spectrometry (ICP-MS) results confirm that the manganese content of treated cell pellets was 10-fold higher than that for untreated cell pellets. To establish that manganese is processed like calcium and deposited as bone, calvaria from the skull of embryonic chicks were grown in culture medium supplemented with 1 mM MnCl2 and 3 mM CaCl2. A banding pattern of high and low T2 values, consistent with mineral deposits with high and low levels of manganese, was observed radiating from the calvarial ridge. The results of ICP-MS studies confirm that manganese-treated calvaria take up increasing amounts of manganese with time in culture. Finally, elemental mapping studies with electron probe microanalysis confirmed local variations in the manganese content of bone newly deposited on the calvarial surface. This is the first reported use of manganese-enhanced MRM to study the process whereby calcium is taken up by osteoblasts cells and deposited as bone. ?? 2007 Elsevier Inc. All rights reserved.

  2. A biokinetic model for manganese for use in radiation protection

    SciTech Connect

    Leggett, Richard Wayne

    2011-01-01

    The ICRP is updating its recommendations regarding occupational exposure to radionuclides including the biokinetic models used to derive dose coefficients and assess bioassay data for internally deposited radionuclides. This report reviews biokinetic data for manganese and proposes a biokinetic model for systemic manganese consistent with the current database. The model provides a more detailed and biologically realistic description of the movement of absorbed manganese in the body than the model currently recommended by the International Commission on Radiological Protection (ICRP). The proposed model and current ICRP model yield broadly similar estimates of dose per unit activity of inhaled or ingested radio-manganese but differ substantially with regard to interpretation of bioassay data.

  3. Nanostructured manganese oxides as highly active water oxidation catalysts: a boost from manganese precursor chemistry.

    PubMed

    Menezes, Prashanth W; Indra, Arindam; Littlewood, Patrick; Schwarze, Michael; Göbel, Caren; Schomäcker, Reinhard; Driess, Matthias

    2014-08-01

    We present a facile synthesis of bioinspired manganese oxides for chemical and photocatalytic water oxidation, starting from a reliable and versatile manganese(II) oxalate single-source precursor (SSP) accessible through an inverse micellar molecular approach. Strikingly, thermal decomposition of the latter precursor in various environments (air, nitrogen, and vacuum) led to the three different mineral phases of bixbyite (Mn2 O3 ), hausmannite (Mn3 O4 ), and manganosite (MnO). Initial chemical water oxidation experiments using ceric ammonium nitrate (CAN) gave the maximum catalytic activity for Mn2 O3 and MnO whereas Mn3 O4 had a limited activity. The substantial increase in the catalytic activity of MnO in chemical water oxidation was demonstrated by the fact that a phase transformation occurs at the surface from nanocrystalline MnO into an amorphous MnOx (1manganese oxides including the newly formed amorphous MnOx . Both Mn2 O3 and the amorphous MnOx exhibit tremendous enhancement in oxygen evolution during photocatalysis and are much higher in comparison to so far known bioinspired manganese oxides and calcium-manganese oxides. Also, for the first time, a new approach for the representation of activities of water oxidation catalysts has been proposed by determining the amount of accessible manganese centers. PMID:25044528

  4. [Early Detection of Manganese Intoxication Based on Occupational History and T1-weighted MRI].

    PubMed

    Fukutake, Toshio; Yano, Hajime; Kushida, Ryutaro; Sunada, Yoshihide

    2016-02-01

    Manganese regulates many enzymes and is essential for normal cell function. Chronic manganese intoxication has an insidious and progressive course terminating to atypical parkinsonism with little therapeutic efficacy. For subjects with chronic manganese exposure such as welders, manganese intoxication can be detected early based on the presence of hyperintensity in the globus pallidus on T(1)-weighted MRI and abnormally high urinary excretion of manganese with a chelating agent even in cases of normal serum/urine level of manganese. PMID:26873238

  5. Regional specificity of manganese accumulation and clearance in the mouse brain: implications for manganese-enhanced MRI.

    PubMed

    Grünecker, B; Kaltwasser, S F; Zappe, A C; Bedenk, B T; Bicker, Y; Spoormaker, V I; Wotjak, C T; Czisch, M

    2013-05-01

    Manganese-enhanced MRI has recently become a valuable tool for the assessment of in vivo functional cerebral activity in animal models. As a result of the toxicity of manganese at higher dosages, fractionated application schemes have been proposed to reduce the toxic side effects by using lower concentrations per injection. Here, we present data on regional-specific manganese accumulation during a fractionated application scheme over 8 days of 30 mg/kg MnCl2 , as well as on the clearance of manganese chloride over the course of several weeks after the termination of the whole application protocol supplying an accumulative dose of 240 mg/kg MnCl2 . Our data show most rapid accumulation in the superior and inferior colliculi, amygdala, bed nucleus of the stria terminalis, cornu ammonis of the hippocampus and globus pallidus. The data suggest that no ceiling effects occur in any region using the proposed application protocol. Therefore, a comparison of basal neuronal activity differences in different animal groups based on locally specific manganese accumulation is possible using fractionated application. Half-life times of manganese clearance varied between 5 and 7 days, and were longest in the periaqueductal gray, amygdala and entorhinal cortex. As the hippocampal formation shows one of the highest T1 -weighted signal intensities after manganese application, and manganese-induced memory impairment has been suggested, we assessed hippocampus-dependent learning as well as possible manganese-induced atrophy of the hippocampal volume. No interference of manganese application on learning was detected after 4 days of Mn(2+) application or 2 weeks after the application protocol. In addition, no volumetric changes induced by manganese application were found for the hippocampus at any of the measured time points. For longitudinal measurements (i.e. repeated manganese applications), a minimum of at least 8 weeks should be considered using the proposed protocol to allow for

  6. Cellular manganese content is developmentally regulated in human dopaminergic neurons

    NASA Astrophysics Data System (ADS)

    Kumar, Kevin K.; Lowe, Edward W., Jr.; Aboud, Asad A.; Neely, M. Diana; Redha, Rey; Bauer, Joshua A.; Odak, Mihir; Weaver, C. David; Meiler, Jens; Aschner, Michael; Bowman, Aaron B.

    2014-10-01

    Manganese (Mn) is both an essential biological cofactor and neurotoxicant. Disruption of Mn biology in the basal ganglia has been implicated in the pathogenesis of neurodegenerative disorders, such as parkinsonism and Huntington's disease. Handling of other essential metals (e.g. iron and zinc) occurs via complex intracellular signaling networks that link metal detection and transport systems. However, beyond several non-selective transporters, little is known about the intracellular processes regulating neuronal Mn homeostasis. We hypothesized that small molecules that modulate intracellular Mn could provide insight into cell-level Mn regulatory mechanisms. We performed a high throughput screen of 40,167 small molecules for modifiers of cellular Mn content in a mouse striatal neuron cell line. Following stringent validation assays and chemical informatics, we obtained a chemical `toolbox' of 41 small molecules with diverse structure-activity relationships that can alter intracellular Mn levels under biologically relevant Mn exposures. We utilized this toolbox to test for differential regulation of Mn handling in human floor-plate lineage dopaminergic neurons, a lineage especially vulnerable to environmental Mn exposure. We report differential Mn accumulation between developmental stages and stage-specific differences in the Mn-altering activity of individual small molecules. This work demonstrates cell-level regulation of Mn content across neuronal differentiation.

  7. Manganese Catalyzed C-H Halogenation.

    PubMed

    Liu, Wei; Groves, John T

    2015-06-16

    The remarkable aliphatic C-H hydroxylations catalyzed by the heme-containing enzyme, cytochrome P450, have attracted sustained attention for more than four decades. The effectiveness of P450 enzymes as highly selective biocatalysts for a wide range of oxygenation reactions of complex substrates has driven chemists to develop synthetic metalloporphyrin model compounds that mimic P450 reactivity. Among various known metalloporphyrins, manganese derivatives have received considerable attention since they have been shown to be versatile and powerful mediators for alkane hydroxylation and olefin epoxidation. Mechanistic studies have shown that the key intermediates of the manganese porphyrin-catalyzed oxygenation reactions include oxo- and dioxomanganese(V) species that transfer an oxygen atom to the substrate through a hydrogen abstraction/oxygen recombination pathway known as the oxygen rebound mechanism. Application of manganese porphyrins has been largely restricted to catalysis of oxygenation reactions until recently, however, due to ultrafast oxygen transfer rates. In this Account, we discuss recently developed carbon-halogen bond formation, including fluorination reactions catalyzed by manganese porphyrins and related salen species. We found that biphasic sodium hypochlorite/manganese porphyrin systems can efficiently and selectively convert even unactivated aliphatic C-H bonds to C-Cl bonds. An understanding of this novel reactivity derived from results obtained for the oxidation of the mechanistically diagnostic substrate and radical clock, norcarane. Significantly, the oxygen rebound rate in Mn-mediated hydroxylation is highly correlated with the nature of the trans-axial ligands bound to the manganese center (L-Mn(V)═O). Based on the ability of fluoride ion to decelerate the oxygen rebound step, we envisaged that a relatively long-lived substrate radical could be trapped by a Mn-F fluorine source, effecting carbon-fluorine bond formation. Indeed, this idea

  8. Alteration at translational but not transcriptional level of transferrin receptor expression following manganese exposure at the blood-CSF barrier in vitro

    SciTech Connect

    Li, G. Jane; Zhao Qiuqu; Zheng Wei . E-mail: wzheng@purdue.edu

    2005-06-01

    Manganese exposure alters iron homeostasis in blood and cerebrospinal fluid (CSF), possibly by acting on iron transport mechanisms localized at the blood-brain barrier and/or blood-CSF barrier. This study was designed to test the hypothesis that manganese exposure may change the binding affinity of iron regulatory proteins (IRPs) to mRNAs encoding transferrin receptor (TfR), thereby influencing iron transport at the blood-CSF barrier. A primary culture of choroidal epithelial cells was adapted to grow on a permeable membrane sandwiched between two culture chambers to mimic blood-CSF barrier. Trace {sup 59}Fe was used to determine the transepithelial transport of iron. Following manganese treatment (100 {mu}M for 24 h), the initial flux rate constant (K {sub i}) of iron was increased by 34%, whereas the storage of iron in cells was reduced by 58%, as compared to controls. A gel shift assay demonstrated that manganese exposure increased the binding of IRP1 and IRP2 to the stem loop-containing mRNAs. Consequently, the cellular concentrations of TfR proteins were increased by 84% in comparison to controls. Assays utilizing RT-PCR, quantitative real-time reverse transcriptase-PCR, and nuclear run off techniques showed that manganese treatment did not affect the level of heterogeneous nuclear RNA (hnRNA) encoding TfR, nor did it affect the level of nascent TfR mRNA. However, manganese exposure resulted in a significantly increased level of TfR mRNA and reduced levels of ferritin mRNA. Taken together, these results suggest that manganese exposure increases iron transport at the blood-CSF barrier; the effect is likely due to manganese action on translational events relevant to the production of TfR, but not due to its action on transcriptional, gene expression of TfR. The disrupted protein-TfR mRNA interaction in the choroidal epithelial cells may explain the toxicity of manganese at the blood-CSF barrier.

  9. Thermodynamics of Manganese Oxides at Bulk and Nanoscale: Phase Formation, Transformation, Oxidation-Reduction, and Hydration

    NASA Astrophysics Data System (ADS)

    Birkner, Nancy R.

    Natural manganese oxides are generally formed in surficial environments that are near ambient temperature and water-rich, and may be exposed to wet-dry cycles and a variety of adsorbate species that influence dramatically their level of hydration. Manganese oxide minerals are often poorly crystalline, nanophase, and hydrous. In the near-surface environment they are involved in processes that are important to life, such as water column oxygen cycling, biomineralization, and transport of minerals/nutrients through soils and water. These processes, often involving transformations among manganese oxide polymorphs, are governed by a complex interplay between thermodynamics and kinetics. Manganese oxides are also used in technology as catalysts, and for other applications. The major goal of this dissertation is to examine the energetics of bulk and nanophase manganese oxide phases as a function of particle size, composition, and surface hydration. Careful synthesis and characterization of manganese oxide phases with different surface areas provided samples for the study of enthalpies of formation by high temperature oxide melt solution calorimetry and of the energetics of water adsorption on their surfaces. These data provide a quantitative picture of phase stability and how it changes at the nanoscale. The surface energy of the hydrous surface of Mn3O4 is 0.96 +/- 0.08 J/m2, of Mn2O3 is 1.29 +/- 0.10 J/m2, and of MnO2 is 1.64 +/- 0.10 J/m2. The surface energy of the anhydrous surface of Mn3O4 is 1.62 +/- 0.08 J/m 2, of Mn2O3 is 1.77 +/- 0.10 J/m 2, and of MnO2 is 2.05 +/- 0.10 J/m2. Supporting preliminary findings (Navrotsky et al., 2010), the spinel phase (Mn3O4) has a lower surface energy (more stabilizing) than bixbyite, while the latter has a smaller surface energy than pyrolusite. These differences significantly change the positions in oxygen fugacity---temperature space of the redox couples Mn3O4-Mn2O 3 and Mn2O3-MnO2 favoring the lower surface enthalpy phase (the

  10. Determining the Oxidation States of Manganese in NT2 Cells and Cultured Astrocytes

    SciTech Connect

    Gunter,K.; Aschner, M.; Miller, L.; Eliseev, R.; Salter, J.; Andersen, K.; Gunter, T.

    2006-01-01

    Excessive brain manganese (Mn) can produce a syndrome called 'manganism', which correlates with loss of striatal dopamine and cell death in the striatum and globus pallidus. The prevalent hypothesis for the cause of this syndrome has been oxidation of cell components by the strong oxidizing agent, Mn{sup 3+}, either formed by oxidation of intracellular Mn{sup 2+} or transported into the cell as Mn{sup 3+}. We have recently used X-ray absorption near edge structure spectroscopy (XANES) to determine the oxidation states of manganese complexes in brain and liver mitochondria and in nerve growth factor (NGF)-induced and non-induced PC12 cells. No evidence was found for stabilization or accumulation of Mn{sup 3+} complexes because of oxidation of Mn{sup 2+} by reactive oxygen species in these tissues. Here we extend these studies of manganese oxidation state to cells of brain origin, human neuroteratocarcinoma (NT2) cells and primary cultures of rat astrocytes. Again we find no evidence for stabilization or accumulation of any Mn{sup 3+} complex derived from oxidation of Mn{sup 2+} under a range of conditions.

  11. Three manganese oxide-rich marine sediments harbor similar communities of acetate-oxidizing manganese-reducing bacteria.

    PubMed

    Vandieken, Verona; Pester, Michael; Finke, Niko; Hyun, Jung-Ho; Friedrich, Michael W; Loy, Alexander; Thamdrup, Bo

    2012-11-01

    Dissimilatory manganese reduction dominates anaerobic carbon oxidation in marine sediments with high manganese oxide concentrations, but the microorganisms responsible for this process are largely unknown. In this study, the acetate-utilizing manganese-reducing microbiota in geographically well-separated, manganese oxide-rich sediments from Gullmar Fjord (Sweden), Skagerrak (Norway) and Ulleung Basin (Korea) were analyzed by 16S rRNA-stable isotope probing (SIP). Manganese reduction was the prevailing terminal electron-accepting process in anoxic incubations of surface sediments, and even the addition of acetate stimulated neither iron nor sulfate reduction. The three geographically distinct sediments harbored surprisingly similar communities of acetate-utilizing manganese-reducing bacteria: 16S rRNA of members of the genera Colwellia and Arcobacter and of novel genera within the Oceanospirillaceae and Alteromonadales were detected in heavy RNA-SIP fractions from these three sediments. Most probable number (MPN) analysis yielded up to 10(6) acetate-utilizing manganese-reducing cells cm(-3) in Gullmar Fjord sediment. A 16S rRNA gene clone library that was established from the highest MPN dilutions was dominated by sequences of Colwellia and Arcobacter species and members of the Oceanospirillaceae, supporting the obtained RNA-SIP results. In conclusion, these findings strongly suggest that (i) acetate-dependent manganese reduction in manganese oxide-rich sediments is catalyzed by members of taxa (Arcobacter, Colwellia and Oceanospirillaceae) previously not known to possess this physiological function, (ii) similar acetate-utilizing manganese reducers thrive in geographically distinct regions and (iii) the identified manganese reducers differ greatly from the extensively explored iron reducers in marine sediments. PMID:22572639

  12. 40 CFR 721.10201 - Cobalt lithium manganese nickel oxide.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Cobalt lithium manganese nickel oxide... Specific Chemical Substances § 721.10201 Cobalt lithium manganese nickel oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as cobalt lithium...

  13. 40 CFR 721.10201 - Cobalt lithium manganese nickel oxide.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Cobalt lithium manganese nickel oxide... Specific Chemical Substances § 721.10201 Cobalt lithium manganese nickel oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as cobalt lithium...

  14. 40 CFR 721.10201 - Cobalt lithium manganese nickel oxide.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Cobalt lithium manganese nickel oxide... Specific Chemical Substances § 721.10201 Cobalt lithium manganese nickel oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as cobalt lithium...

  15. 40 CFR 721.10003 - Manganese heterocyclic tetraamine complex (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... complex (generic). 721.10003 Section 721.10003 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.10003 Manganese heterocyclic tetraamine complex (generic). (a) Chemical... as manganese heterocyclic tetraamine complex (PMNs P-98-625/626/627/628/629 and P-00-614/617)...

  16. Manganese encrustation of zygospores of a chlamydomonas (chlorophyta: volvocales).

    PubMed

    Schulz-Baldes, M; Lewin, R A

    1975-06-13

    In media containing normal trace-element supplements, but not in manganese-deficient media, zygospores of a new species of Chlamydomonas (isolated from soil) become encrusted with a dark brown mineral coating. Staining with benzidine indicates that the encrustation is rich in manganese. This has been confirmed by x-ray analysis in combination with a scanning electron microscope. PMID:17798436

  17. 40 CFR 721.10011 - Barium calcium manganese strontium oxide.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Barium calcium manganese strontium... Specific Chemical Substances § 721.10011 Barium calcium manganese strontium oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as barium...

  18. 40 CFR 721.10011 - Barium calcium manganese strontium oxide.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Barium calcium manganese strontium... Specific Chemical Substances § 721.10011 Barium calcium manganese strontium oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as barium...

  19. 40 CFR 721.10011 - Barium calcium manganese strontium oxide.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Barium calcium manganese strontium... Specific Chemical Substances § 721.10011 Barium calcium manganese strontium oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as barium...

  20. 40 CFR 721.10011 - Barium calcium manganese strontium oxide.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Barium calcium manganese strontium... Specific Chemical Substances § 721.10011 Barium calcium manganese strontium oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as barium...

  1. 40 CFR 721.10011 - Barium calcium manganese strontium oxide.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Barium calcium manganese strontium... Specific Chemical Substances § 721.10011 Barium calcium manganese strontium oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as barium...

  2. Ambient Concentrations of Manganese Compounds in EPA Region 5

    EPA Science Inventory

    This indicator presents trends in ambient concentrations of manganese in EPA Region 5 from 2000 to 2009. This information shows how concentrations of manganese, a hazardous air pollutant that can harm human health in exposed populations, have changed in the last 10 years in a ...

  3. 64 FR 23675 - Electrolytic Manganese Dioxide From Greece and Japan

    Federal Register 2010, 2011, 2012, 2013, 2014

    1999-05-03

    ... orders on imports of electrolytic manganese dioxide from Greece and Japan (54 FR 15243). The Commission..., including the text of subpart F of part 207, are published at 63 FR 30599, June 5, 1998, and may be... COMMISSION Electrolytic Manganese Dioxide From Greece and Japan AGENCY: United States International...

  4. The Characterization and Structure of the Manganese-responsive Transcriptional Regulator ScaR†§

    PubMed Central

    Stoll, Kate E.; Draper, William E.; Kliegman, Joseph I.; Golynskiy, Misha V.; Brew-Appiah, Rhoda A. T.; Phillips, Rebecca K.; Brown, Hattie K.; Breyer, Wendy A.; Jakubovics, Nicholas S.; Jenkinson, Howard F.; Brennan, Richard G.; Cohen, Seth M.; Glasfeld, Arthur

    2013-01-01

    The streptococcal coaggregation regulator (ScaR) of Streptococcus gordonii is a manganese-dependent transcriptional regulator. When intracellular manganese concentrations become elevated, ScaR represses transcription of the scaCBA operon, which encodes a manganese uptake transporter. A member of the DtxR/MntR family of metalloregulators, ScaR shares sequence similarity with other family members, and many metal-binding residues are conserved. Here, we show that ScaR is an active dimer, with two dimers binding the 46-bp scaC operator. Each ScaR subunit binds two manganese ions, and the protein is activated by a variety of other metal ions, including Cd2+, Co2+ and Ni2+, but not Zn2+. The crystal structure of apo-ScaR reveals a tertiary and quaternary structure similar to its homolog, the iron-responsive regulator DtxR. While each DtxR subunit binds a metal ion in two sites, labeled primary and ancillary, crystal structures of ScaR determined in the presence of Cd2+ and Zn2+ show only a single occupied metal binding site that is novel to ScaR. The site analogous to the primary site in DtxR is unoccupied, and the ancillary site is absent from ScaR. Instead, metal ions bind to ScaR at a site labeled “secondary”, which is composed of Glu80, Cys123, His125 and Asp160 and lies roughly 5 Å away from where the ancillary site would be predicted to exist. This difference suggests that ScaR and its closely related homologs are activated by a mechanism distinct from that of either DtxR or MntR. PMID:19795834

  5. Manganese oxide-supported iron Fischer-Tropsch synthesis catalysts: physical and catalytic characterization

    SciTech Connect

    Kreitman, K.M.

    1986-01-01

    In this study, manganese oxide-supported iron (Fe/MnO) was prepared by impregnation of powdered manganese (II) oxide with aqueous iron(III) nitrate and subjected to various calcination and reduction treatments. It was then employed as a catalyst for Fischer-Tropsch Synthesis (FTS) and its steady-state activity and selectivity behavior was observed. The FTS reaction studies were run with nearly equimolal carbon monoxide/hydrogen feed at 515 and 540 K, 7.9 and 14.8 bar pressure. Feed conversion level was kept low in order to avoid transport limitations, and was varied by adjusting space velocity. The FTS reaction rate decreased strongly with increasing conversion. Compared to unpromoted iron catalysts, the Fe/MnO catalysts were more active for the water-gas shift reaction and less selective for methane and alcohols, especially at higher conversion, lower temperature and higher pressure. The olefin selectivity was high and secondary hydrogenation was not apparent. Catalysts calcined at higher temperature exhibited stronger effects of promotion, and yielded unusually high selectivity for C/sub 2/ to C/sub 4/ hydrocarbons at low temperature and high pressure. The general conclusion is that manganese promotion or iron can promote FTS selectivity towards low molecular weight olefins, but at the expense of high carbon dioxide formation. The Fe/MnO was also physically examined using Moessbauer spectroscopy and X-ray diffraction. Iron and manganese were found to interact strongly in the calcined catalyst, though extensive phase separation occurred during reduction. The promoting effects are apparently due to partial surface coverage of iron with MnO, the extent of which is enhanced by wetter reducing conditions.

  6. Oxidation state of marine manganese nodules

    USGS Publications Warehouse

    Piper, D.Z.; Basler, J.R.; Bischoff, J.L.

    1984-01-01

    Analyses of the bulk oxidation state of marine manganese nodules indicates that more than 98% of the Mn in deep ocean nodules is present as Mn(IV). The samples were collected from three quite different areas: the hemipelagic environment of the Guatemala Basin, the pelagic area of the North Pacific, and seamounts in the central Pacific. Results of the study suggest that todorokite in marine nodules is fully oxidized and has the following stoichiometry: (K, Na, Ca, Ba).33(Mg, Cu, Ni).76Mn5O22(H2O)3.2. ?? 1984.

  7. AM1* parameters for manganese and iron.

    PubMed

    Kayi, Hakan; Clark, Timothy

    2010-06-01

    We report the parameterization of AM1* for the elements manganese and iron. The basis sets for both metals contain one set each of s-, p- and d-orbitals. AM1* parameters are now available for H, C, N, O and F (which use the original AM1 parameters), Al, Si, P, S, Cl, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Br, Zr, Mo, I and Au. The performance and typical errors of AM1* are discussed for Mn and Fe, and are compared with available NDDO Hamiltonians. PMID:19937261

  8. [Characterization of manganese oxidation by Pseudomonas sp. QJX-1].

    PubMed

    Zhou, Na-Na; Bai, Yao-Hui; Liang, Jin-Song; Luo, Jin-Ming; Liu, Rui-Ping; Hu, Cheng-Zhi; Yuan, Lin-Jiang

    2014-02-01

    A manganese-oxidizing bacteria (QJX-1) was isolated from the soil of a manganese mine. It was identified as Pseudomonas sp. QJX-1 by 16S rDNA sequencing. Experimental results showed that the Pseudomonas sp. QJX-1 has a multi-copper oxidase gene CumA, which is an essential component for manganese oxidation by Pseudomonas sp. Under the condition of low initial inoculum level (D600, 0.020), 5.05 mg x L(-1 Mn2+ could be oxidized by QJX-1 within 48 h with a conversion rate of as high as 99.4%. In comparison with the eutrophic conditions, the oligotrophic condition dramatically increased the biological manganese oxidation rate. Biofilm formation by employing the quartz sand could further improve the oxidation rate of Mn2+. Based on these results, it is speculated that biological manganese oxidation in underground water treatment is comparatively high. PMID:24812972

  9. Treatability of manganese by sodium silicate and chlorine

    SciTech Connect

    Robinson, F.B.; Ronk, S.K. )

    1987-11-01

    Manganese sequestering by nearly simultaneous additions of sodium silicate and sodium hypochlorite was studied in laboratory-prepared waters. Under conditions of near-neutral pH and 150-250 mg/liter of alkalinity as CaCO{sub 3}, 1-2 mg manganese/liter could be sequestered for up to one day. Less effective manganese treatability was found at pH 8 than at pH 7. Additionally, at pH 7 the best results were obtained when neither silicate nor hypochlorite was added because of the slow manganese oxidation rate by oxygen alone. Aging of diluted stock silicate solutions prior to dosing also resulted in poor treatment; the presence of background silica increased the treatment effectiveness only slightly. Overall, manganese was less treatable by this method than iron under the same treatment conditions.

  10. Manganese consumption and recycling flow model. Information circular/1995

    SciTech Connect

    Gabler, R.C.

    1995-04-01

    The report follows the flow of manganese through its metallurgical and chemical applications and highlights areas where significant losses occur owing to downgrading, export, or disposal. The study indicates that materials containing 695,000 short tons (st) of manganese were consumed domestically in 1990. Scrap recovery specifically for manganese recycling was insignificant. However, considerable manganese was recycled through processing operations as a minor component of ferrous and nonferrous scrap and steel slag. The major loss category is manganese lost in steel processing, 323,156 st or 46 pct of the 1990 apparent consumption. Most of this loss reports to steelmaking slags. Recovery from slags is technically feasible, but is not economically feasible.

  11. Homeostatic and toxic mechanisms regulating manganese uptake, retention, and elimination.

    PubMed

    Roth, Jerome A

    2006-01-01

    This review attempts to summarize and clarify our basic knowledge as to the various factors that potentially influence the risks imposed from chronic exposure to high atmospheric levels of manganese (Mn). The studies describe the interrelationship of the different systems in the body that regulate Mn homeostasis by characterizing specific, biological components involved in its systemic and cellular uptake and its elimination from the body. A syndrome known as manganism occurs when individuals are exposed chronically to high levels of Mn, consisting of reduced response speed, intellectual deficits, mood changes, and compulsive behaviors in the initial stages of the disorder to more prominent and irreversible extrapyramidal dysfunction resembling Parkinson's disease upon protracted exposure. Mn intoxication is most often associated with occupations in which abnormally high atmospheric concentrations prevail, such as in welding and mining. There are three potentially important routes by which Mn in inspired air can gain access the body to: 1) direct uptake into the CNS via uptake into the olfactory or trigeminal presynaptic nerve endings located in the nasal mucosa and the subsequent retrograde axonal transport directly into the CNS; 2) transport across the pulmonary epithelial lining and its subsequent deposition into lymph or blood; and/or 3) mucocilliary elevator clearance from the lung and the subsequent ingestion of the metal in the gastrointestinal tract. Each of these processes and their overall contribution to the uptake of Mn in the body is discussed in this review as well as a description of the various mechanisms that have been proposed for the transport of Mn across the bloodbrain barrier which include both a transferrin-dependent and a transferrin-independent process that may involve store-operated Ca channels. PMID:16629164

  12. Development of Lymantria dispar affected by manganese in food.

    PubMed

    Kula, Emanuel; Martinek, Petr; Chromcová, Lucie; Hedbávný, Josef

    2014-10-01

    We studied the response of gypsy moth (Lymantria dispar (Linnaeus) (Lepidoptera: Lymantriidae)) to the content of manganese in food in the laboratory breeding of caterpillars. The food of the caterpillars {Betula pendula Roth (Fagales: Betulaceae) leaves} was contaminated by dipping in the solution of MnCl2 · 4H2O with manganese concentrations of 0, 0.5, 5 and 10 mg ml(-1), by which differentiated manganese contents (307; 632; 4,087 and 8,124 mg kg(-1)) were reached. Parameters recorded during the rearing were as follows: effect of manganese on food consumption, mortality and length of the development of caterpillars, pupation and hatching of imagoes. At the same time, manganese concentrations were determined in the offered and unconsumed food, excrements, and exuviae of the caterpillars, pupal cases and imagoes by using the AAS method. As compared with the control, high manganese contents in the food of gypsy moth caterpillars affected the process of development particularly by increased mortality of the first instar caterpillars (8 % mortality for caterpillars with no Mn contamination (T0) and 62 % mortality for subjects with the highest contamination by manganese (T3)), by prolonged development of the first-third instar (18.7 days (T0) and 27.8 days (T3)) and by increased food consumption of the first-third instar {0.185 g of leaf dry matter (T0) and 0.483 g of leaf dry matter (T3)}. The main defence strategy of the caterpillars to prevent contamination by the increased manganese content in food is the translocation of manganese into frass and exuviae castoff in the process of ecdysis. In the process of development, the content of manganese was reduced by excretion in imagoes to 0.5 % of the intake level even at its maximum inputs in food. PMID:25028315

  13. Essentiality, toxicity, and uncertainty in the risk assessment of manganese.

    PubMed

    Boyes, William K

    2010-01-01

    Risk assessments of manganese by inhalation or oral routes of exposure typically acknowledge the duality of manganese as an essential element at low doses and a toxic metal at high doses. Previously, however, risk assessors were unable to describe manganese pharmacokinetics quantitatively across dose levels and routes of exposure, to account for mass balance, and to incorporate this information into a quantitative risk assessment. In addition, the prior risk assessment of inhaled manganese conducted by the U.S. Environmental Protection Agency (EPA) identified a number of specific factors that contributed to uncertainty in the risk assessment. In response to a petition regarding the use of a fuel additive containing manganese, methylcyclopentadienyl manganese tricarbonyl (MMT), the U.S. EPA developed a test rule under the U.S. Clean Air Act that required, among other things, the generation of pharmacokinetic information. This information was intended not only to aid in the design of health outcome studies, but also to help address uncertainties in the risk assessment of manganese. To date, the work conducted in response to the test rule has yielded substantial pharmacokinetic data. This information will enable the generation of physiologically based pharmacokinetic (PBPK) models capable of making quantitative predictions of tissue manganese concentrations following inhalation and oral exposure, across dose levels, and accounting for factors such as duration of exposure, different species of manganese, and changes of age, gender, and reproductive status. The work accomplished in response to the test rule, in combination with other scientific evidence, will enable future manganese risk assessments to consider tissue dosimetry more comprehensively than was previously possible. PMID:20077286

  14. Effect of quantity and route of administration of manganese monoxide on feed intake and serum manganese in ruminants

    SciTech Connect

    Black, J.R.; Ammerman, C.B.; Henry, P.R.

    1985-02-01

    The experiment investigated effects of high quantities of manganese and route of administration (diet versus capsule-dosed) on feed intake and blood characteristics in sheep. Twenty-four Florida native or Florida native by St. Croix crossbred wethers, 47 kg initially, were assigned randomly to eight treatments including basal diet supplemented with 0, 3000, 6000, or 9000 ppm manganese as a reagent grade manganese monoxide or basal diet plus gelatin capsules containing the equivalent of 0, 3000, 6000, or 9000 ppm manganese based on intake of the previous day. Three sheep per treatment were provided feed and tap water for ad libitum intake. Sheep were fed basal diet for 7 days followed by a 21-day experimental period, then placed back on the basal diet for 7 days. Average daily feed intake was reduced by increasing supplemental manganese, regardless of route. Animals dosed by capsule consumed less feed than those administered manganese in the diet. Serum manganese increased as manganese supplementation increased, but route of administration had no effect.

  15. THE STATE OF MANGANESE IN THE PHOTOSYNTHETIC APPARATUS. II. X-RAY ABSORPTION EDGE STUDIES ON MANGANESE IN PHOTOSYNTHETIC MEMBRANES

    SciTech Connect

    Kirby, J. A.; Goodin, D. B.; Wydrzynski, T.; Robertson, A. S.; Klein, M. P.

    1980-11-01

    X-ray absorption spectra at the Manganese K-edge are presented for spinach chloroplasts, and chloroplasts which have been Tris-treated and hence unable to evolve oxygen. A significant change in the electronic environment of manganese is observed and is attributed to the release of manganese from the thylakoid membranes with a concomitant change in oxidation state. A correlation of the K-edge energy, defined as the energy at the first inflection point, with coordination charge has been established for a number of manganese compounds of known structure and oxidation state. Comparison of the manganese K-edge energies of the chloroplast samples with the reference compounds places the average oxidation state of the chloroplasts between +2 and +3. Using the edge spectra for Tris-treated membranes which were osmotically shocked to remove the released manganese, difference edge spectra were synthesized to approximate the active pool of manganese. Coordination charge predictions for this fraction are consistent with an average resting oxidation state higher than +2. The shape at the edge is also indicative of heterogeneity of the manganese site, of low symmetry, or both.

  16. Interplay between Manganese and Iron in Pneumococcal Pathogenesis: Role of the Orphan Response Regulator RitR

    PubMed Central

    Ong, Cheryl-Lynn Y.; Potter, Adam J.; Trappetti, Claudia; Walker, Mark J.; Jennings, Michael P.; Paton, James C.

    2013-01-01

    Streptococcus pneumoniae (the pneumococcus) is a major human pathogen that is carried asymptomatically in the nasopharynx by up to 70% of the human population. Translocation of the bacteria into internal sites can cause a range of diseases, such as pneumonia, otitis media, meningitis, and bacteremia. This transition from nasopharynx to growth at systemic sites means that the pneumococcus needs to adjust to a variety of environmental conditions, including transition metal ion availability. Although it is an important nutrient, iron potentiates oxidative stress, and it is established that in S. pneumoniae, expression of iron transport systems and proteins that protect against oxidative stress are regulated by an orphan response regulator, RitR. In this study, we investigated the effect of iron and manganese ion availability on the growth of a ritR mutant. Deletion of ritR led to impaired growth of bacteria in high-iron medium, but this phenotype could be suppressed with the addition of manganese. Measurement of metal ion accumulation indicated that manganese prevents iron accumulation. Furthermore, the addition of manganese also led to a reduction in the amount of hydrogen peroxide produced by bacterial cells. Studies of virulence in a murine model of infection indicated that RitR was not essential for pneumococcal survival and suggested that derepression of iron uptake systems may enhance the survival of pneumococci in some niches. PMID:23184523

  17. Mutation in HFE gene decreases manganese accumulation and oxidative stress in the brain after olfactory manganese exposure.

    PubMed

    Ye, Qi; Kim, Jonghan

    2016-06-01

    Increased accumulation of manganese (Mn) in the brain is significantly associated with neurobehavioral deficits and impaired brain function. Airborne Mn has a high systemic bioavailability and can be directly taken up into the brain, making it highly neurotoxic. While Mn transport is in part mediated by several iron transporters, the expression of these transporters is altered by the iron regulatory gene, HFE. Mutations in the HFE gene are the major cause of the iron overload disorder, hereditary hemochromatosis, one of the prevalent genetic diseases in humans. However, whether or not HFE mutation modifies Mn-induced neurotoxicity has not been evaluated. Therefore, our goal was to define the role of HFE mutation in Mn deposition in the brain and the resultant neurotoxic effects after olfactory Mn exposure. Mice carrying the H67D HFE mutation, which is homologous to the H63D mutation in humans, and their control, wild-type mice, were intranasally instilled with MnCl2 with different doses (0, 0.2, 1.0 and 5.0 mg kg(-1)) daily for 3 days. Mn levels in the blood, liver and brain were determined using inductively-coupled plasma mass spectrometry (ICP-MS). H67D mutant mice showed significantly lower Mn levels in the blood, liver, and most brain regions, especially in the striatum, while mice fed an iron-overload diet did not. Moreover, mRNA expression of ferroportin, an essential exporter of iron and Mn, was up-regulated in the striatum. In addition, the levels of isoprostane, a marker of lipid peroxidation, were increased in the striatum after Mn exposure in wild-type mice, but were unchanged in H67D mice. Together, our results suggest that the H67D mutation provides decreased susceptibility to Mn accumulation in the brain and neurotoxicity induced by inhaled Mn. PMID:27295312

  18. Manganese removal during bench-scale biofiltration.

    PubMed

    Burger, Mark S; Mercer, Stephen S; Shupe, Gordon D; Gagnon, Graham A

    2008-12-01

    As biological manganese (Mn) removal becomes a more popular water treatment technology, there is still a large gap in understanding the key mechanisms and range of operational characteristics. This research aimed to expand on previous bench-scale experiments by directly comparing small filtration columns inoculated with indigenous biofilms from a Mn filtration plant and filtration columns inoculated with a liquid suspension of Leptothrix discophora SP-6. Batch tests found that in the absence of manganese oxidizing bacteria Mn was not removed by air alone, whereas a mixed population and Leptothrix strain achieved greater than 90% removal of Mn. The bench-scale biofiltration experiments found that biological filters can be inoculated with a pure culture of L. discophora SP-6 and achieve a similar removal of indigenous biofilm. While Mn oxidizing bacteria (MOB) seem to be necessary for the auto-catalytic nature of these biological filters, Mn removal is achieved with a combination of adsorption to Mn oxides and biological oxidation. Additionally, it was demonstrated that biological Mn removal is possible over a broader "field of activity" (e.g., Mn removal occurred at a pH level as low as 6.5) than has previously been reported. The ability of this treatment technology to work over a broader range of influent conditions allows for more communities to consider biological treatment as an option to remove Mn from their drinking water. PMID:18809196

  19. THE MANGANESE MERCURY STAR π1 BOOTIS

    PubMed Central

    Montgomery, John Wm.; Aller, Lawrence H.

    1969-01-01

    High-dispersion plates secured with the Coudé spectrograph of the Lick 120 inch telescope have been used to analyze the peculiar A star π1 Bootis. Spectral-energy distribution measurements are combined with line-intensity data for iron and manganese in two stages of ionization to obtain a fit with model atmospheres for Teff = 13,000°K and log g = 4. The influence of adopted T and g on the derived abundances is discussed. Although C, O, Mg, Si, Ti, Cr, and Fe appear to have nearly normal (i.e., solar) abundances, strontium appears to be enhanced in abundance by an order of magnitude, and scandium is about 50 times overabundant, while manganese and yttrium appear to be two orders of magnitude overabundant. If the identification of gallium is correct, this element is overabundant by a factor approaching 100,000; while if λ3983.90 is to be attributed to HgII, as Bidelman suggests, the overabundance of this element is many orders of magnitude. PMID:16578698

  20. Thermochemistry of iron manganese oxide spinels

    SciTech Connect

    Guillemet-Fritsch, Sophie; Navrotsky, Alexandra . E-mail: anavrotsky@ucdavis.edu; Tailhades, Philippe; Coradin, Herve; Wang Miaojun

    2005-01-15

    Oxide melt solution calorimetry has been performed on iron manganese oxide spinels prepared at high temperature. The enthalpy of formation of (Mn{sub x}Fe{sub 1-x}){sub 3}O{sub 4} at 298K from the oxides, tetragonal Mn{sub 3}O{sub 4} (hausmannite) and cubic Fe{sub 3}O{sub 4} (magnetite), is negative from x=0 to x=0.67 and becomes slightly positive for 0.670.6) spinels of intermediate compositions. The enthalpies of formation are discussed in terms of three factors: oxidation-reduction relative to the end-members, cation distribution, and tetragonality. A combination of measured enthalpies and Gibbs free energies of formation in the literature provides entropies of mixing. {delta}S{sub mix}, consistent with a cation distribution in which all trivalent manganese is octahedral and all other ions are randomly distributed for x>0.5, but the entropy of mixing appears to be smaller than these predicted values for x<0.4.

  1. Stabilisation of carbonyl free amidinato-manganese(II) hydride complexes: "masked" sources of manganese(I) in organometallic synthesis.

    PubMed

    Fohlmeister, Lea; Jones, Cameron

    2016-01-28

    Reaction of the amidinato-manganese(ii) bromide complex, [{(κ(2)-N,N'-Piso)Mn(μ-Br)}3(THF)2] (Piso = [(DipN)2CBu(t)](-), Dip = 2,6-diisopropylphenyl), with K[BHEt3] affords the first example of a structurally authenticated amidinato-manganese(ii) hydride complex, [{(N-,η(3)-arene-Piso)Mn(μ-H)2}2], via a process which involves a change in the amidinate coordination mode. Treatment of the bulkier precursor complex, [{(Piso'')Mn(μ-Br)}n] (Piso'' = [(Dip''N)2CBu(t)](-), Dip'' = C6H2Pr(i)2(CPh3)-2,6,4), with K[BHEt3] did not lead to an isolable manganese hydride complex, but its reaction with the magnesium(i) complex, [{((Mes)Nacnac)Mg}2] ((Mes)Nacnac = [(MesNCMe)2CH](-), Mes = mesityl), did. This reaction presumably proceeds via a reactive manganese(i) intermediate, which abstracts hydrogen from a reaction component to give [{(κ(2)-N,N'-Piso'')Mn(μ-H)}3]. A comparison of the reactivities of [{(N-,η(3)-arene-Piso)Mn(μ-H)2}2] and the isomorphous manganese(i) complex, [{(N-,η(3)-arene-Piso)Mn}2], toward CO, O2 and N2O was carried out. Reactions with the manganese(i) and manganese(ii) species gave identical results, namely the formation of the manganese(i) carbonyl complex, [(κ(2)-N,N'-Piso)Mn(CO)4] (reactions with CO), and the manganese(iii)-μ-oxo complex, [{(κ(2)-N,N'-Piso)Mn(μ-O)}2] (reactions with O2 and N2O). These results indicate that [{(N-,η(3)-arene-Piso)Mn(μ-H)2}2] can act as a "masked" source of an amidinato-manganese(i) fragment in synthetic transformations. PMID:26674008

  2. Manganese and copper fluxes from continental margin sediments

    SciTech Connect

    Heggie, D.; Klinkhammer, G.; Cullen, D.

    1987-05-01

    Total dissolvable Cu and Mn have been measured in sea water collected from the continental shelf of the eastern Bering Sea. Copper concentrations of <3 nmole kg/sup -1/ were measured over the shelf break but concentrations increased to >4 nmole kg/sup -1/ inshore of a hydrographic front over the 100 m isobath. Manganese concentrations also were low over the shelf break, <10 nmole kg/sup -1/, and increased systematically to concentrations >10 nmole kg/sup -1/ inshore of the hydrographic front. Depth distributions of Mn at all continental shelf stations showed gradients into the sediments, with concentrations typically >20 nmole kg/sup -1/ in a bottom layer extending about 30 m off the bottom. Benthic Cu and Mn fluxes are indicated by cross-shelf pore water profiles that show interfacial concentrations more than an order of magnitude greater than in bottom water. These data and the results of a model of metal transport across the shelf suggest that Cu and Mn fluxes, estimated at 2 and 18 nmole cm/sup -2/y/sup -1/, respectively, from continental shelf sediments may be one source of these metals to the deep sea.

  3. Compendium and synthesis of bacterial manganese reduction rates

    NASA Astrophysics Data System (ADS)

    Bandstra, Joel Z.; Ross, Daniel E.; Brantley, Susan L.; Burgos, William D.

    2011-01-01

    We have compiled time-series concentration data for the biological reduction of manganese(III/IV) published between 1985 and 2004 and fit these data with a simple hyperbolic rate expression or, when appropriate, one of its limiting forms. The compiled data and rate constants are available in Electronic Annex EA-1. The zero- and first-order rate constants appear to follow a log-normal distribution that could be used, for example, in predictive modeling of Mn-oxide reduction in a reactive transport scenario. We have also included details of the experimental procedures used to generate each time-series data-set in our compilation. These meta-data—mostly pertaining to the type and concentration of micro-organism, electron donor, and electron acceptor—enable us to examine the rate data for trends. We have computed a number of rudimentary, mono-variate statistics on the compiled data with the hope of stimulating both more detailed statistical analyses of the data and new experiments to fill gaps in the existing data-set. We have also analyzed the data with parametric models based on the log-normal distribution and rate equations that are hyperbolic in the concentration of cells and Mn available for reduction. This parametric analysis allows us to provide best estimates of zero- and first-order rate constants both ignoring and accounting for the meta-data.

  4. Controlled release of manganese into water from coated experimental fertilizers: laboratory characterization.

    PubMed

    Novillo, J; Rico, M I; Alvarez, J M

    2001-03-01

    The release of manganese into water from controlled-release formulations containing manganese EDTA or manganese lignosulfonate was studied. These fertilizers were obtained in the laboratory by adhering the source of manganese over urea pellets and by adding a coating. The materials used as adhesives and coatings were mixtures of rosins plus tricalcium phosphate. With regard to the chemical composition, these formulations conformed to national and international standards for commercial fertilizers. The rate of release of manganese was a function of both the source of manganese used and the coating thickness. Under the same conditions the release of manganese was greater for formulations with manganese EDTA than with manganese lignosulfonate. To predict the kinetic behaviors of the two series of formulations, mathematical equations were established. The manganese source plus rosin coatings improved the handling and storage characteristics of the commercial urea pellets. The study of the rosin coatings using scanning electron microscopy showed that they were compact and homogeneous. PMID:11312854

  5. Selection and Use of Manganese Dioxide by Neanderthals

    PubMed Central

    Heyes, Peter J.; Anastasakis, Konstantinos; de Jong, Wiebren; van Hoesel, Annelies; Roebroeks, Wil; Soressi, Marie

    2016-01-01

    Several Mousterian sites in France have yielded large numbers of small black blocs. The usual interpretation is that these ‘manganese oxides’ were collected for their colouring properties and used in body decoration, potentially for symbolic expression. Neanderthals habitually used fire and if they needed black material for decoration, soot and charcoal were readily available, whereas obtaining manganese oxides would have incurred considerably higher costs. Compositional analyses lead us to infer that late Neanderthals at Pech-de-l’Azé I were deliberately selecting manganese dioxide. Combustion experiments and thermo-gravimetric measurements demonstrate that manganese dioxide reduces wood’s auto-ignition temperature and substantially increases the rate of char combustion, leading us to conclude that the most beneficial use for manganese dioxide was in fire-making. With archaeological evidence for fire places and the conversion of the manganese dioxide to powder, we argue that Neanderthals at Pech-de-l’Azé I used manganese dioxide in fire-making and produced fire on demand. PMID:26922901

  6. Manganese carbonates as possible biogenic relics in Archean settings

    NASA Astrophysics Data System (ADS)

    Rincón-Tomás, Blanca; Khonsari, Bahar; Mühlen, Dominik; Wickbold, Christian; Schäfer, Nadine; Hause-Reitner, Dorothea; Hoppert, Michael; Reitner, Joachim

    2016-07-01

    Carbonate minerals such as dolomite, kutnahorite or rhodochrosite are frequently, but not exclusively generated by microbial processes. In recent anoxic sediments, Mn(II)carbonate minerals (e.g. rhodochrosite, kutnahorite) derive mainly from the reduction of Mn(IV) compounds by anaerobic respiration. The formation of huge manganese-rich (carbonate) deposits requires effective manganese redox cycling in an oxygenated atmosphere. However, putative anaerobic pathways such as microbial nitrate-dependent manganese oxidation, anoxygenic photosynthesis and oxidation in ultraviolet light may facilitate manganese cycling even in an early Archean environment, without the availability of oxygen. In addition, manganese carbonates precipitate by microbially induced processes without change of the oxidation state, e.g. by pH shift. Hence, there are several ways how these minerals could have been formed biogenically and deposited in Precambrian sediments. We will summarize microbially induced manganese carbonate deposition in the presence and absence of atmospheric oxygen and we will make some considerations about the biogenic deposition of manganese carbonates in early Archean settings.

  7. Critical Aspects of Alloying of Sintered Steels with Manganese

    NASA Astrophysics Data System (ADS)

    Hryha, Eduard; Dudrova, Eva; Nyborg, Lars

    2010-11-01

    This study examines the sintering behavior and properties of Fe-0.8Mn-0.5C manganese powder metallurgy steels. The study focuses on the influence of mode of alloying—admixing using either high-purity electrolytic manganese or medium carbon ferromanganese as well as the fully prealloying of water-atomized powder. Three main aspects were studied during the whole sintering process—microstructure development, interparticle necks evolution, and changes in the behavior of manganese carrier particles during both heating and sintering stages. The prealloyed powder shows considerable improvement in carbon homogenization and interparticle neck development in comparison with admixed materials. The first indication of pearlite for the fully prealloyed material was registered at ~1013 K (740 °C) in comparison with ~1098 K (825 °C) in the case of the admixed systems. The negative effect of the oxidized residuals of manganese carrier particles and high microstructure inhomogeneity, which is a characteristic feature of admixed systems, is reflected in the lower values of the mechanical properties. The worst results in this respect were obtained for the system admixed with electrolytic manganese because of more intensive manganese sublimation and resulting oxidation at lower temperatures. According to the results of X-ray photoelectron spectroscopy and high-resolution scanning electron microscopy and energy dispersive X-ray analyses, the observed high brittleness of admixed materials is connected with intergranular decohesion failure associated with manganese oxide formation on the grain boundaries.

  8. Selection and Use of Manganese Dioxide by Neanderthals.

    PubMed

    Heyes, Peter J; Anastasakis, Konstantinos; de Jong, Wiebren; van Hoesel, Annelies; Roebroeks, Wil; Soressi, Marie

    2016-01-01

    Several Mousterian sites in France have yielded large numbers of small black blocs. The usual interpretation is that these 'manganese oxides' were collected for their colouring properties and used in body decoration, potentially for symbolic expression. Neanderthals habitually used fire and if they needed black material for decoration, soot and charcoal were readily available, whereas obtaining manganese oxides would have incurred considerably higher costs. Compositional analyses lead us to infer that late Neanderthals at Pech-de-l'Azé I were deliberately selecting manganese dioxide. Combustion experiments and thermo-gravimetric measurements demonstrate that manganese dioxide reduces wood's auto-ignition temperature and substantially increases the rate of char combustion, leading us to conclude that the most beneficial use for manganese dioxide was in fire-making. With archaeological evidence for fire places and the conversion of the manganese dioxide to powder, we argue that Neanderthals at Pech-de-l'Azé I used manganese dioxide in fire-making and produced fire on demand. PMID:26922901

  9. Methanogenesis from wastewater stimulated by addition of elemental manganese

    PubMed Central

    Qiao, Sen; Tian, Tian; Qi, Benyu; Zhou, Jiti

    2015-01-01

    This study presents a novel procedure for accelerating methanogenesis from wastewater by adding elemental manganese into the anaerobic digestion system. The results indicated that elemental manganese effectively enhanced both the methane yield and the production rate. Compared to the control test without elemental manganese, the total methane yield and production rate with 4 g/L manganese addition increased 3.4-fold (from 0.89 ± 0.03 to 2.99 ± 0.37 M/gVSS within 120 h) and 4.4-fold (from 6.2 ± 0.1 to 27.2 ± 2.2 mM/gVSS/h), respectively. Besides, more acetate consumption and less propionate generation were observed during the methanogenesis with manganese. Further studies demonstrated that the elemental manganese served as electron donors for the methanogenesis from carbon dioxide, and the final proportion of methane in the total generated gas with 4 g/L manganese addition reached 96.9%, which was 2.1-fold than that of the control (46.6%). PMID:26244609

  10. Selection and Use of Manganese Dioxide by Neanderthals

    NASA Astrophysics Data System (ADS)

    Heyes, Peter J.; Anastasakis, Konstantinos; de Jong, Wiebren; van Hoesel, Annelies; Roebroeks, Wil; Soressi, Marie

    2016-02-01

    Several Mousterian sites in France have yielded large numbers of small black blocs. The usual interpretation is that these ‘manganese oxides’ were collected for their colouring properties and used in body decoration, potentially for symbolic expression. Neanderthals habitually used fire and if they needed black material for decoration, soot and charcoal were readily available, whereas obtaining manganese oxides would have incurred considerably higher costs. Compositional analyses lead us to infer that late Neanderthals at Pech-de-l’Azé I were deliberately selecting manganese dioxide. Combustion experiments and thermo-gravimetric measurements demonstrate that manganese dioxide reduces wood’s auto-ignition temperature and substantially increases the rate of char combustion, leading us to conclude that the most beneficial use for manganese dioxide was in fire-making. With archaeological evidence for fire places and the conversion of the manganese dioxide to powder, we argue that Neanderthals at Pech-de-l’Azé I used manganese dioxide in fire-making and produced fire on demand.

  11. Hot coal gas desulfurization with manganese-based sorbents

    SciTech Connect

    Lynch, D.; Hepworth, M.T.

    1993-09-01

    The focus of work being performed on Hot Coal Gas Desulfurization is primarily in the use of zinc ferrite and zinc titanate sorbents; however, prior studies at the US Steel Fundamental Research Laboratories in Monroeville, PA, by E.T. Turkdogan indicated that an alternate sorbent, manganese dioxide-containing ore in mixture with alumina (75 wt % ore + 25 wt % Al{sub 2}/O{sub 3}) may be a viable alternative to zinc-based sorbents. Manganese, for example, has a lower vapor pressure in the elemental state than zinc hence it is not as likely to undergo depletion from the sorbent surface upon loading and regeneration cycles. Also manganese oxide is less readily reduced to the elemental state than iron hence the range of reduction potentials for oxygen is somewhat greater than for zinc ferrite. In addition, thermodynamic analysis of the manganese-oxygen-sulfur system shows it to be less amenable to sulfation than zinc ferrite. Potential also exists for utilization of manganese higher temperatures than zinc ferrite or zinc titanate. This presentation gives the thermodynamic background for consideration of manganese-based sorbents as an alternative to zinc ferrite. To date the work which has been in progress for nine months is limited at this stage to thermogravimetric testing of four formulations of manganese-alumina sorbents to determine the optimum conditions of pelletization and induration to produce reactive pellets.

  12. Hot coal gas desulfurization with manganese-based sorbents

    SciTech Connect

    Hepworth, M.T.; Ben-Slimane, R.

    1994-12-01

    The focus of work being performed on Hot Coal Gas Desulfurization at the Morgantown Energy Technology Center is primarily in the use of zinc ferrite and zinc titanate sorbents; however, prior studies indicated that an alternate sorbent, manganese dioxide-containing ore in mixture with alumina (75 wt % ore + 25 wt % Al{sub 2}O{sub 3}) may be a viable alternative to zinc-based sorbents. Manganese, for example, has a lower vapor pressure in the elemental state than zinc hence it is not as likely to undergo depletion from the sorbent surface upon loading and regeneration cycles. Also manganese oxide is less readily reduced to the elemental state than iron hence the range of reduction potentials for oxygen is somewhat greater than for zinc ferrite. In addition, thermodynamic analysis of the manganese-oxygen-sulfur system shows it to be less amenable to sulfation than zinc ferrite. Potential also exists for utilization of manganese at higher temperatures than zinc ferrite or zinc titanate. This annual topical report documents progress in pelletizing and testing via thermo-gravimetric analysis of individual pellet formulations of manganese ore/alumina combinations and also manganese carbonate/alumina with two binders, dextrin and bentonite.

  13. Potential Role of Epigenetic Mechanism in Manganese Induced Neurotoxicity

    PubMed Central

    Tarale, Prashant; Chakrabarti, Tapan; Sivanesan, Saravanadevi; Naoghare, Pravin; Bafana, Amit; Krishnamurthi, Kannan

    2016-01-01

    Manganese is a vital nutrient and is maintained at an optimal level (2.5–5 mg/day) in human body. Chronic exposure to manganese is associated with neurotoxicity and correlated with the development of various neurological disorders such as Parkinson's disease. Oxidative stress mediated apoptotic cell death has been well established mechanism in manganese induced toxicity. Oxidative stress has a potential to alter the epigenetic mechanism of gene regulation. Epigenetic insight of manganese neurotoxicity in context of its correlation with the development of parkinsonism is poorly understood. Parkinson's disease is characterized by the α-synuclein aggregation in the form of Lewy bodies in neuronal cells. Recent findings illustrate that manganese can cause overexpression of α-synuclein. α-Synuclein acts epigenetically via interaction with histone proteins in regulating apoptosis. α-Synuclein also causes global DNA hypomethylation through sequestration of DNA methyltransferase in cytoplasm. An individual genetic difference may also have an influence on epigenetic susceptibility to manganese neurotoxicity and the development of Parkinson's disease. This review presents the current state of findings in relation to role of epigenetic mechanism in manganese induced neurotoxicity, with a special emphasis on the development of Parkinson's disease. PMID:27314012

  14. Kinetic patterns in the formation of nanosized manganese-manganese oxide systems

    NASA Astrophysics Data System (ADS)

    Surovoi, E. P.; Bugerko, L. N.; Surovaya, V. E.; Zaikonnikova, T. M.

    2016-03-01

    Transformations in nanosized manganese films are studied by means of optical spectroscopy, microscopy, and gravimetry at different film thicknesses ( d = 4-108 nm) and temperatures of heat treatment ( T = 373-673 K). It is found that the kinetic curves of conversion are satisfactorily described in the terms of linear, inverse logarithmic, cubic, and logarithmic laws. The contact potential difference is measured for Mn and MnO films, and photo EMF is measured for Mn-MnO systems. An energy band diagram is constructed for Mn-MnO systems. A model for the thermal transformation of Mn films is proposed that includes stages of oxygen adsorption, the redistribution of charge carriers in the contact field of Mn-MnO, and manganese(II) oxide formation.

  15. BDNF and Huntingtin protein modifications by manganese: implications for striatal medium spiny neuron pathology in manganese neurotoxicity.

    PubMed

    Stansfield, Kirstie H; Bichell, Terry Jo; Bowman, Aaron B; Guilarte, Tomás R

    2014-12-01

    High levels of manganese (Mn) exposure decrease striatal medium spiny neuron (MSN) dendritic length and spine density, but the mechanism(s) are not known. The Huntingtin (HTT) gene has been functionally linked to cortical brain-derived neurotrophic factor (BDNF) support of striatal MSNs via phosphorylation at serine 421. In Huntington's disease, pathogenic CAG repeat expansions of HTT decrease synthesis and disrupt transport of cortical-striatal BDNF, which may contribute to disease, and Mn is a putative environmental modifier of Huntington's disease pathology. Thus, we tested the hypothesis that changes in MSN dendritic morphology Mn due to exposure are associated with decreased BDNF levels and alterations in Htt protein. We report that BDNF levels are decreased in the striatum of Mn-exposed non-human primates and in the cerebral cortex and striatum of mice exposed to Mn. Furthermore, proBDNF and mature BDNF concentrations in primary cortical and hippocampal neuron cultures were decreased by exposure to Mn confirming the in vivo findings. Mn exposure decreased serine 421 phosphorylation of Htt in cortical and hippocampal neurons and increased total Htt levels. These data strongly support the hypothesis that Mn-exposure-related MSN pathology is associated with decreased BDNF trophic support via alterations in Htt. PMID:25099302

  16. BDNF and Huntingtin protein modifications by Manganese: Implications for striatal medium spiny neuron pathology in manganese neurotoxicity

    PubMed Central

    Stansfield, Kirstie H.; Bichell, Terry Jo; Bowman, Aaron B.; Guilarte, Tomás R.

    2014-01-01

    High levels of manganese (Mn) exposure decreases striatal medium spiny neuron (MSN) dendritic length and spine density, but the mechanism(s) are not known. The Huntingtin (HTT) gene has been functionally linked to cortical brain-derived neurotrophic factor (BDNF) support of striatal MSNs via phosphorylation at serine 421 (S421). In Huntington's disease, pathogenic CAG-repeat expansions of HTT decrease synthesis and disrupt transport of cortical-striatal BDNF contributing to disease, and Mn is a putative environmental modifier of Huntington's disease pathology. Thus, we tested the hypothesis that changes in MSN dendritic morphology due to Mn exposure are associated with decreased BDNF levels and alterations in Htt protein. We report that BDNF levels are decreased in the striatum of Mn-exposed non-human primates and in the cerebral cortex and striatum of mice exposed to Mn. Further, proBDNF and mature BDNF concentrations in primary cortical and hippocampal neuron cultures were decreased by exposure to Mn confirming the in vivo findings. Mn exposure decreased S421 phosphorylation of Htt in cortical and hippocampal neurons and increased total Htt levels. These data strongly support the hypothesis that Mn-exposure related MSN pathology is associated with decreased BDNF trophic support via alterations in Htt. PMID:25099302

  17. Molecular identification of indigenous manganese solubilising bacterial biodiversity from manganese mining deposits.

    PubMed

    Ghosh, Shreya; Mohanty, Sansuta; Nayak, Sanghamitra; Sukla, Lala B; Das, Alok P

    2016-03-01

    Manganese (Mn) ranks twelfth among the most exuberant metal present in the earth's crust and finds its imperative application in the manufacturing steel, chemical, tannery, glass, and battery industries. Solubilisation of Mn can be performed by several bacterial strains which are useful in developing environmental friendly solutions for mining activities. The present investigation aims to isolate and characterize Mn solubilising bacteria from low grade ores from Sanindipur Manganese mine of Sundargh district in Odisha state of India. Four morphologically distinct bacterial strains showing visible growth on Mn supplemented plates were isolated. Mn solubilising ability of the bacterial strains was assessed by visualizing the lightening of the medium appearing around the growing colonies. Three isolates were gram negative and rod shaped while the remaining one was gram positive, coccobacilli. Molecular identification of the isolates was carried out by 16S rRNA sequencing and the bacterial isolates were taxonomically classified as Bacillus anthrasis MSB 2, Acinetobacter sp. MSB 5, Lysinibacillus sp. MSB 11, and Bacillus sp. MMR-1 using BLAST algorithm. The sequences were deposited in NCBI GenBank with the accession number KP635223, KP635224, KP635225 and JQ936966, respectively. Manganese solubilisation efficiency of 40, 96, 97.5 and 48.5% were achieved by MMR-1, MSB 2, MSB 5 and MSB 11 respectively. The efficiency of Mn solubilisation is suggested with the help of a pH variation study. The results are discussed in relation to the possible mechanisms involved in Manganese solubilisation efficiency of bacterial isolates. PMID:26471873

  18. Structural and surface changes of copper modified manganese oxides

    NASA Astrophysics Data System (ADS)

    Gac, Wojciech; Słowik, Grzegorz; Zawadzki, Witold

    2016-05-01

    The structural and surface properties of manganese and copper-manganese oxides were investigated. The oxides were prepared by the redox-precipitation method. X-ray diffraction and electron microscopy studies evidenced transformation of cryptomelane-type nanoparticles with 1-D channel structure into the large MnO crystallites with regular rippled-like surface patterns under reduction conditions. The development of Cu/CuO nanorods from strongly dispersed species was evidenced. Coper-modified manganese oxides showed good catalytic performance in methanol steam reforming reaction for hydrogen production. Low selectivity to CO was observed in the wide range of temperatures.

  19. Manganese abundances in Galactic bulge red giants

    NASA Astrophysics Data System (ADS)

    Barbuy, B.; Hill, V.; Zoccali, M.; Minniti, D.; Renzini, A.; Ortolani, S.; Gómez, A.; Trevisan, M.; Dutra, N.

    2013-11-01

    Context. Manganese is mainly produced in type II SNe during explosive silicon burning, in incomplete Si-burning regions, and depends on several nucleosynthesis environment conditions, such as mass cut between the matter ejected and falling back onto the remnant, electron and neutron excesses, mixing fallback, and explosion energy. Manganese is also produced in type Ia SNe. Aims: The aim of this work is the study of abundances of the iron-peak element Mn in 56 bulge giants, among which 13 are red clump stars. Four bulge fields along the minor axis are inspected. The study of abundances of Mn-over-Fe as a function of metallicity in the Galactic bulge may shed light on its production mechanisms. Methods: High-resolution spectra were obtained using the FLAMES+UVES spectrograph on the Very Large Telescope. The spectra were obtained within a program to observe 800 stars using the GIRAFFE spectrograph, together with the present UVES spectra. Results: We aim at identifying the chemical evolution of manganese, as a function of metallicity, in the Galactic bulge. We find [Mn/Fe] ~ -0.7 at [Fe/H] ~ -1.3, increasing to a solar value at metallicities close to solar, and showing a spread around - 0.7 ≲ [Fe/H] ≲ -0.2, in good agreement with other work on Mn in bulge stars. There is also good agreement with chemical evolution models. We find no clear difference in the behaviour of the four bulge fields. Whereas [Mn/Fe] vs. [Fe/H] could be identified with the behaviour of the thick disc stars, [Mn/O] vs. [O/H] has a behaviour running parallel, at higher metallicities, compared to thick disc stars, indicating that the bulge enrichment might have proceeded differently from that of the thick disc. Observations collected at the European Southern Observatory, Paranal, Chile (ESO programmes 71.B-0617A, 73.B0074A, and GTO 71.B-0196).Tables 1-6 and Figs. 1-6 are available in electronic form at http://www.aanda.org

  20. Hydrothermal Manganese Mineralization Near the Samoan Hotspot

    NASA Astrophysics Data System (ADS)

    Hein, J. R.; Staudigel, H.; Koppers, A.; Hart, S. R.; Dunham, R.

    2006-12-01

    The thickest beds of hydrothermal manganese oxides recovered to date from the global ocean were collected from a volcanic cone in the south Pacific. In April 2005, samples were dredged aboard the R.V. Kilo Moana from a volcanic cone on the lower flank of Tulaga seamount (about 2,700 m water depth; 14° 39.222' S; 170° 1.730' W), located 115 km SW of Vailulu'u, the volcanically and hydrothermally active center of the Samoan hotspot. Additional hydrothermal manganese samples were collected off Ofu Island (dredge Alia 107), 72 km to the WSW of Vailulu'u. Manganese-oxide beds up to 9 cm thick are composed of birnessite and 10 Å manganates. Some layers consist of Mn-oxide columnar structures 4 cm long and 1 cm wide, which have not been described previously. The mean Mn and Fe contents of 18 samples are 51 weight percent and 0.76 weight percent, respectively. Elevated concentrations of Li (mean 0.11 wt. percent) are indicators of a hydrothermal origin, and distinguishes these samples, along with the high Mn and low Fe contents, from hydrogenetic Fe-Mn crusts. Other enriched elements include Ba (mean 0.14 percent), Cu (249 ppm), Mo (451 ppm), Ni (400 ppm), Zn (394 ppm), V (214 ppm), and W (132 ppm). Chondrite-normalized REE patterns show large negative Ce anomalies and LREE enrichments, both characteristic of hydrothermal Mn deposits. Small negative Eu anomalies are not typical of hydrothermal deposits and can be explained either by the absence of leaching of plagioclase by the hydrothermal fluids or by the precipitation of Eu-rich minerals, such as barite and anhydrite, at depth. The high base-metal contents indicate that sulfides are not forming deeper in the hydrothermal system or that such deposits are being leached by the ascending fluids. Textures of the thickest Mn deposits indicate that the Mn oxides formed below the seabed from ascending fluids during multiple phases of waxing and waning hydrothermal pulses. The deposits were later exposed at the seafloor by

  1. Distributions of Manganese, Iron, and Manganese-Oxidizing Bacteria In Lake Superior Sediments of Different Organic Carbon Content

    NASA Technical Reports Server (NTRS)

    Richardson, Laurie L.; Nealson, Kenneth H.

    1989-01-01

    Profiles of oxygen, soluble and particulate manganese and iron, organic carbon and nitrogen were examined in Lake Superior sediment cores, along with the distribution and abundance of heterotrophic and manganese oxidizing bacteria. Analyses were performed using cores collected with the submersible Johnson Sea Link II. Three cores, exhibiting a range of organic carbon content, were collected from the deepest basin in Lake Superior and the north and south ends of the Caribou trough, and brought to the surface for immediate analysis. Minielectrode profiles of oxygen concentration of the three cores were carried out using a commercially available minielectrode apparatus. Oxygen depletion to less than 1% occurred within 4 cm of the surface for two of the cores, but not until approximately 15 cm for the core from the south basin of the Caribou trough. The three cores exhibited very different profiles of soluble, as well as leachable, manganese and iron, suggesting different degrees of remobilization of these metals in the sediments. Vertical profiles of viable bacteria and Mn oxidizing bacteria, determined by plating and counting, showed that aerobic (and facultatively aerobic) heterotrophic bacteria were present at the highest concentrations near the surface and decreased steadily with depth, while Mn oxidizing bacteria were concentrations primarily at and above the oxic/anoxic interface. Soluble manganese in the pore waters, along with abundant organic carbon, appeared to enhance the presence of manganese oxidizing bacteria, even below the oxic/anoxic interface. Profiles of solid-phase leachable manganese suggested a microbial role in manganese reprecipitation in these sediments.

  2. Isotopic evidence for organic matter oxidation by manganese reduction in the formation of stratiform manganese carbonate ore

    USGS Publications Warehouse

    Okita, P.M.; Maynard, J.B.; Spiker, E. C.; Force, E.R.

    1988-01-01

    Unlike other marine-sedimentary manganese ore deposits, which are largely composed of manganese oxides, the primary ore at Molango (Hidalgo State, Mexico) is exclusively manganese carbonate (rhodochrosite, Mn-calcite, kutnahorite). Stable isotope studies of the carbonates from Molango provide critical new information relevant to the controversy over syngenetic and diagenetic models of stratiform manganese deposit formation. Negative ??13C values for carbonates from mineralized zones at Molango are strongly correlated with manganese content both on a whole rock scale and by mineral species. Whole rock ??13C data fall into three groups: high-grade ore = -16.4 to -11.5%.; manganese-rich, sub-ore-grade = -5.2 to 0%.; and unmineralized carbonates = 0 to +2.5%. (PDB). ??18O data show considerable overlap in values among the three groups: +4.8 to -2.8, -5.4 to -0.3%., and -7.4 to +6.2 (PDB), respectively. Isotopic data for individual co-existing minerals suggest a similar separation of ??13C values: ??13C values from calcite range from -1.1 to +0.7%. (PDB), whereas values from rhodochrosite are very negative, -12.9 to -5.5%., and values from kutnahorite or Mn-calcite are intermediate between calcite and rhodochrosite. 13C data are interpreted to indicate that calcite (i.e. unmineralized carbonate) formed from a normal marine carbon reservoir. However, 13C data for the manganese-bearing carbonates suggest a mixed seawater and organic source of carbon. The presence of only trace amounts of pyrite suggests sulfate reduction may have played a minor part in oxidizing organic matter. It is possible that manganese reduction was the predominant reaction that oxidized organic matter and that it released organic-derived CO2 to produce negative ??13C values and manganese carbonate mineralization. ?? 1988.

  3. Untangling the Manganese-α-Synuclein Web

    PubMed Central

    Peres, Tanara Vieira; Parmalee, Nancy L.; Martinez-Finley, Ebany J.; Aschner, Michael

    2016-01-01

    Neurodegenerative diseases affect a significant portion of the aging population. Several lines of evidence suggest a positive association between environmental exposures, which are common and cumulative in a lifetime, and development of neurodegenerative diseases. Environmental or occupational exposure to manganese (Mn) has been implicated in neurodegeneration due to its ability to induce mitochondrial dysfunction, oxidative stress, and α-synuclein (α-Syn) aggregation. The role of the α-Syn protein vis-a-vis Mn is controversial, as it seemingly plays a duplicitous role in neuroprotection and neurodegeneration. α-Syn has low affinity for Mn, however an indirect interaction cannot be ruled out. In this review we will examine the current knowledge surrounding the interaction of α-Syn and Mn in neurodegenerative process. PMID:27540354

  4. Untangling the Manganese-α-Synuclein Web.

    PubMed

    Peres, Tanara Vieira; Parmalee, Nancy L; Martinez-Finley, Ebany J; Aschner, Michael

    2016-01-01

    Neurodegenerative diseases affect a significant portion of the aging population. Several lines of evidence suggest a positive association between environmental exposures, which are common and cumulative in a lifetime, and development of neurodegenerative diseases. Environmental or occupational exposure to manganese (Mn) has been implicated in neurodegeneration due to its ability to induce mitochondrial dysfunction, oxidative stress, and α-synuclein (α-Syn) aggregation. The role of the α-Syn protein vis-a-vis Mn is controversial, as it seemingly plays a duplicitous role in neuroprotection and neurodegeneration. α-Syn has low affinity for Mn, however an indirect interaction cannot be ruled out. In this review we will examine the current knowledge surrounding the interaction of α-Syn and Mn in neurodegenerative process. PMID:27540354

  5. Manganese recovery from secondary resources: a green process for carbothermal reduction and leaching of manganese bearing hazardous waste.

    PubMed

    Chandra, Navin; Amritphale, S S; Pal, Deepti

    2011-02-15

    During the hydrometallurgical extraction of zinc by electrowinning process, a hazardous solid waste called anode mud is generated. It contains large quantity of manganese oxides (55-80%) and lead dioxide (6-16%). Due to the presence of a large quantity of lead, the anode mud waste is considered hazardous and has to be disposed of in secure landfills, which is costly, wastes available manganese and valuable land resources. For recovery of manganese content of anode mud, a process comprising of carbothermal treatment using low density oil (LDO) followed by sulphuric acid leaching is developed. PMID:21115220

  6. Neuropsychological Motor Outcomes in Adults from Airborne Manganese Exposure

    EPA Science Inventory

    Background: The literature on manganese (Mn) is dominated by occupational exposures of adults exposed often to high levels without protection. Neuropsychological adverse health effects are similar to Parkinson’s Disease with psychomotor slowing, tremor, cognitive and mood ...

  7. Manganese resources of the Cuyuna range, east-central Minnesota

    SciTech Connect

    Beltrame, R.J.; Holtzman, R.C.; Wahl, T.E.

    1981-01-01

    The Cuyuna range, located in east-central Minnesota, consists of a sequence of argillite, siltstone, iron-formation, graywacke, slate, and quartzite of early Proterozoic age. Manganese-bearing materials occur within the iron-rich strata of the Trommald Formation and the Rabbit Lake Formation. Computer-assisted resource estimates, based on exploration drill hole information, indicate that the Cuyuna range contains a minimum of 176 million metric tons (MMT) of marginally economic manganiferous rock with an average grade of 10.46 weight percent manganese. The calculated 18.5 MMT of manganese on the Cuyuna range could supply this country's needs for this important and strategic metal for nearly 14 years. An additional resource of 6.9 MMT of manganese metal is available in the lower grade deposits The vast majority of these calculated resources are extractable by current surface mining techniques.

  8. Manganese, Iron, and sulfur cycling in Louisiana continental shelf sediments

    EPA Science Inventory

    Sulfate reduction is considered the primary pathway for organic carbon remineralization on the northern Gulf of Mexico Louisiana continental shelf (LCS) where bottom waters are seasonally hypoxic, yet limited information is available on the importance of iron and manganese cyclin...

  9. The Relationship of the Lipoprotein SsaB, Manganese, and Superoxide Dismutase in Streptococcus sanguinis Virulence for Endocarditis

    PubMed Central

    Crump, Katie E.; Bainbridge, Brian; Brusko, Sarah; Turner, Lauren S.; Ge, Xiuchun; Stone, Victoria; Xu, Ping; Kitten, Todd

    2014-01-01

    Summary Streptococcus sanguinis colonizes teeth and is an important cause of infective endocarditis. Our prior work showed that the lipoprotein SsaB is critical for S. sanguinis virulence for endocarditis and belongs to the LraI family of conserved metal transporters. In this study, we demonstrated that an ssaB mutant accumulates less manganese and iron than its parent. A mutant lacking the manganese-dependent superoxide dismutase, SodA, was significantly less virulent than wild-type in a rabbit model of endocarditis, but significantly more virulent than the ssaB mutant. Neither the ssaB nor the sodA mutation affected sensitivity to phagocytic killing or efficiency of heart valve colonization. Animal virulence results for all strains could be reproduced by growing bacteria in serum under physiological levels of O2. SodA activity was reduced, but not eliminated in the ssaB mutant in serum and in rabbits. Growth of the ssaB mutant in serum was restored upon addition of Mn2+ or removal of O2. Antioxidant supplementation experiments suggested that superoxide and hydroxyl radicals were together responsible for the ssaB mutant’s growth defect. We conclude that manganese accumulation mediated by the SsaB transport system imparts virulence by enabling cell growth in oxygen through SodA-dependent and independent mechanisms. PMID:24750294

  10. Giant negative magnetoresistance in Manganese-substituted Zinc Oxide

    PubMed Central

    Wang, X. L.; Shao, Q.; Zhuravlyova, A.; He, M.; Yi, Y.; Lortz, R.; Wang, J. N.; Ruotolo, A.

    2015-01-01

    We report a large negative magnetoresistance in Manganese-substituted Zinc Oxide thin films. This anomalous effect was found to appear in oxygen-deficient films and to increase with the concentration of Manganese. By combining magnetoresistive measurements with magneto-photoluminescence, we demonstrate that the effect can be explained as the result of a magnetically induced transition from hopping to band conduction where the activation energy is caused by the sp-d exchange interaction. PMID:25783664

  11. Formation of methyl iodide on a natural manganese oxide.

    PubMed

    Allard, Sébastien; Gallard, Hervé; Fontaine, Claude; Croué, Jean-Philippe

    2010-08-01

    This paper demonstrates that manganese oxides can initiate the formation of methyl iodide, a volatile compound that participates to the input of iodine into the atmosphere. The formation of methyl iodide was investigated using a natural manganese oxide in batch experiments for different conditions and concentrations of iodide, natural organic matter (NOM) and manganese oxide. Methyl iodide was formed at concentrations manganese dioxide in the presence of iodide. However, the implication of elemental iodine cannot be excluded at acidic pH. Manganese oxides can then participate with ferric oxides to the formation of methyl iodide in soils and sediments. The formation of methyl iodide is unlikely in technical systems such as drinking water treatment i.e. for ppt levels of iodide and low contact times with manganese oxides. PMID:20580399

  12. Chronic manganese poisoning in the dry battery industry

    PubMed Central

    Emara, A. M.; El-Ghawabi, S. H.; Madkour, O. I.; El-Samra, G. H.

    1971-01-01

    Emara, A. M., El-Ghawabi, S. H., Madkour, O. I., and El-Samra, G. H. (1971). Brit. J. industr. Med., 28, 78-82. Chronic manganese poisoning in the dry battery industry. A survey was carried out on 36 workers in the dry battery industry exposed to dust containing 65 to 70% manganese oxide. Eight (22·2%) were found to have neuropsychiatric manifestations, six (16·6%) had chronic manganese psychosis, one had left hemi-parkinsonism, and one had left choreoathetosis. An environmental study revealed a high concentration of manganese dust at the main working areas, far exceeding the accepted MAC. The manganese level in blood was almost within the normal range. Coproporphyrin in urine was normal. The electroencephalogram was abnormal in only two of the affected workers (25%) but there was no association between this and the clinical manifestations or duration of exposure. The concentration of manganese dust in air showed some association with the prevalence and rapidity of effect on workers according to their occupation. However, individual susceptibility was apparent. The shortest latent period was one year. PMID:5101169

  13. Low copper and high manganese levels in prion protein plaques

    USGS Publications Warehouse

    Johnson, Christopher J.; Gilbert, P.U.P.A.; Abrecth, Mike; Baldwin, Katherine L.; Russell, Robin E.; Pedersen, Joel A.; McKenzie, Debbie

    2013-01-01

    Accumulation of aggregates rich in an abnormally folded form of the prion protein characterize the neurodegeneration caused by transmissible spongiform encephalopathies (TSEs). The molecular triggers of plaque formation and neurodegeneration remain unknown, but analyses of TSE-infected brain homogenates and preparations enriched for abnormal prion protein suggest that reduced levels of copper and increased levels of manganese are associated with disease. The objectives of this study were to: (1) assess copper and manganese levels in healthy and TSE-infected Syrian hamster brain homogenates; (2) determine if the distribution of these metals can be mapped in TSE-infected brain tissue using X-ray photoelectron emission microscopy (X-PEEM) with synchrotron radiation; and (3) use X-PEEM to assess the relative amounts of copper and manganese in prion plaques in situ. In agreement with studies of other TSEs and species, we found reduced brain levels of copper and increased levels of manganese associated with disease in our hamster model. We also found that the in situ levels of these metals in brainstem were sufficient to image by X-PEEM. Using immunolabeled prion plaques in directly adjacent tissue sections to identify regions to image by X-PEEM, we found a statistically significant relationship of copper-manganese dysregulation in prion plaques: copper was depleted whereas manganese was enriched. These data provide evidence for prion plaques altering local transition metal distribution in the TSE-infected central nervous system.

  14. Manganese micro-nodules on ancient brick walls.

    PubMed

    López-Arce, P; García-Guinea, J; Fierro, J L G

    2003-01-20

    Romans, Jews, Arabs and Christians built the ancient city of Toledo (Spain) with bricks as the main construction material. Manganese micro-nodules (circa 2 microm in diameter) have grown under the external bio-film surface of the bricks. Recent anthropogenic activities such as industrial emissions, foundries, or traffic and housing pollution have further altered these old bricks. The energy-dispersive X-ray microanalyses (XPS) of micro-nodules show Al, Si, Ca, K, Fe and Mn, with some carbon species. Manganese atoms are present only as Mn(4+) and iron as Fe(3+) (FeOOH-Fe(2)O(3) mixtures). The large concentration of alga biomass of the River Tagus and the Torcón and Guajaraz reservoirs suggest manganese micro-nodules are formed either from water solutions rich in anthropogenic MnO(4)K in a reduction environment (from Mn(7+) to Mn(4+)) or by oxidation mechanisms from dissolved Mn(2+) (from Mn(2+) to Mn(4+)) linked to algae biofilm onto the ancient brick surfaces. Ancient wall surfaces were also studied by scanning electron microscopy (SEM-EDS) and X-ray diffraction (XRD). Chemical and biological analyses of the waters around Toledo are also analysed for possible sources of manganese. Manganese micro-nodules on ancient brick walls are good indicators of manganese pollution. PMID:12526915

  15. Thermoluminescence evidence for light-induced oxidation of tyrosine and histidine residues in manganese-depleted photosystem II particles.

    PubMed

    Allakhverdiev, S I; Klimov, V V; Demeter, S

    1992-02-01

    In the thermoluminescence (TL) glow curve of photosystem II, particles depleted of manganese, a tyrosine modifier, 7-chloro-4-nitrobenz-2-oxa-1,3-diazole (NBD) abolishes the TL band appearing around -55 degrees C (TL-55). Addition of a histidine modifier, diethylpyrocarbonate results in the disappearance of the band peaking around -30 degrees C (TL-30). NBD treatment also abolishes the EPR signal IIfast of oxidized tyrosine donor, Yz, and inhibits the electron transport from diphenylcarbazide to 2,6-dichlorophenol-indophenol. It is concluded that the TL-55 and TL-30 bands can be assigned to oxidized tyrosine (Yz+) and histidine (His+) residues, respectively, which participate in electron transfer from manganese to the reaction center of chlorophyll, P680+. PMID:1551436

  16. [Study on the bioleaching mechanism of manganse (II) from manganese-electrolytic residue by manganese-resistant strain Fusarium sp].

    PubMed

    Huang, Yu-Xia; Cao, Jian-Bing; Li, Xiao-Ming; Yang, Qi; Huang, Hua-Jun; Liu, Xian; Yang, Hui

    2011-09-01

    The manganse bioleaching mechanism by a manganese-resistant strain Fusarium sp. was investigated, through analyzing the bioleaching rate and manganese-electrolytic residue characterizations with the presence of Fusarium sp. and with the addition of organic acids. Special attention was paid to explore the relationship among the manganese's leaching rate, pH, and organic acid concentration during Fusarium sp. bioleaching process. The research results showed that, with the addition of Fusarium sp., some looser and more porous manganese-electrolytic residues could be obtained. And after 47 hours, the leaching rate reached to 84% which was 2.30 times higher than that leached by individual organic acid even after 130 hours; the leaching rate of manganese and the concentrations of organic acids increased at the initial stage and then decreased, while pH was the reversed. Additionally, the concentration of Succinic acid and L-Malic acid reached their crest value (11.12 g/L and 10.23 g/L) at 57 and 62 hours respectively. Yet the pH reached the lowest (4.09) at 29 h, which implied that, Fusarium sp. and organic acid produced played an important role in the leaching of manganese, leading to a high-efficiency and time-saving process. However, due to the high density of manganese-electrolytic residue and the concurrence of the produce and consumption of organic acid together with the adsorption and complexation, the relationship among the extraction rate for manganese ion, pH, and the concentration of organic acid produced could not be described by simple linear correlation and the leaching rate decreased significantly in the later stage. PMID:22165242

  17. THE STATE OF MANGANESE IN THE PHOTOSYNTHETIC APPARATUS: FIRST VIEW OF THE MANGANESE SITES BY X-RAY ABSORPTION SPECTROSCOPY

    SciTech Connect

    Kirby, Jon A.; Goodin, D. B.; Robertson, A. S.; Smith, J. P.; Thompson, A. C.; Klein, M. P.

    1980-11-01

    Manganese atoms have long been implicated as essential ingredients in photosynthetic oxygen evolution. Heretofore they have eluded direct observation. We report the first direct observation, by X-ray Absorption Spectroscopy, of the Mn sites in chloroplasts isolated from Spinacia oleracea. The manganese in chlorplasts is commonly thought to exist in two pools. The major pool, corresponding to two-thirds of the manganese, can be reversibly released with concomitant loss of oxygen evolving capacity, and has thus come to be assigned as the active pool. The role of the remanant one-third, or tightly bound pool is moot. Our analysis of the Extended X-ray Absorption Fine Structure of the active pool is consistent with a bridged dimeric structure involving two manganese atoms separated by about 2.7 {Angstroms}. The distance between manganese and bridging ligands is about 1.8 {Angstrom}. Analysis of the edge region suggests that the manganese in the active pool exists in oxidation states somewhat higher than Mn(II).

  18. Six-coordinate manganese(3+) in catalysis by yeast manganese superoxide dismutase

    SciTech Connect

    Sheng, Yuewei; Gralla, Edith Butler; Schumacher, Mikhail; Cascio, Duilio; Cabelli, Diane E.; Valentine, Joan Selverstone

    2012-10-10

    Reduction of superoxide (O{sub 2}{sup -}) by manganese-containing superoxide dismutase occurs through either a 'prompt protonation' pathway, or an 'inner-sphere' pathway, with the latter leading to formation of an observable Mn-peroxo complex. We recently reported that wild-type (WT) manganese superoxide dismutases (MnSODs) from Saccharomyces cerevisiae and Candida albicans are more gated toward the 'prompt protonation' pathway than human and bacterial MnSODs and suggested that this could result from small structural changes in the second coordination sphere of manganese. We report here that substitution of a second-sphere residue, Tyr34, by phenylalanine (Y34F) causes the MnSOD from S. cerevisiae to react exclusively through the 'inner-sphere' pathway. At neutral pH, we have a surprising observation that protonation of the Mn-peroxo complex in the mutant yeast enzyme occurs through a fast pathway, leading to a putative six-coordinate Mn3+ species, which actively oxidizes O{sub 2}{sup -} in the catalytic cycle. Upon increasing pH, the fast pathway is gradually replaced by a slow proton-transfer pathway, leading to the well-characterized five-coordinate Mn{sup 3+}. We here propose and compare two hypothetical mechanisms for the mutant yeast enzyme, diffeeing in the structure of the Mn-peroxo complex yet both involving formation of the active six-coordinate Mn{sup 3+} and proton transfer from a second-sphere water molecule, which has substituted for the -OH of Tyr34, to the Mn-peroxo complex. Because WT and the mutant yeast MnSOD both rest in the 2+ state and become six-coordinate when oxidized up from Mn{sup 2+}, six-coordinate Mn{sup 3+} species could also actively function in the mechanism of WT yeast MnSODs.

  19. Six-coordinate manganese(3+) in catalysis by yeast manganese superoxide dismutase

    PubMed Central

    Sheng, Yuewei; Butler Gralla, Edith; Schumacher, Mikhail; Cascio, Duilio; Cabelli, Diane E.; Selverstone Valentine, Joan

    2012-01-01

    Reduction of superoxide () by manganese-containing superoxide dismutase occurs through either a “prompt protonation” pathway, or an “inner-sphere” pathway, with the latter leading to formation of an observable Mn-peroxo complex. We recently reported that wild-type (WT) manganese superoxide dismutases (MnSODs) from Saccharomyces cerevisiae and Candida albicans are more gated toward the “prompt protonation” pathway than human and bacterial MnSODs and suggested that this could result from small structural changes in the second coordination sphere of manganese. We report here that substitution of a second-sphere residue, Tyr34, by phenylalanine (Y34F) causes the MnSOD from S. cerevisiae to react exclusively through the “inner-sphere” pathway. At neutral pH, we have a surprising observation that protonation of the Mn-peroxo complex in the mutant yeast enzyme occurs through a fast pathway, leading to a putative six-coordinate Mn3+ species, which actively oxidizes in the catalytic cycle. Upon increasing pH, the fast pathway is gradually replaced by a slow proton-transfer pathway, leading to the well-characterized five-coordinate Mn3+. We here propose and compare two hypothetical mechanisms for the mutant yeast enzyme, differing in the structure of the Mn-peroxo complex yet both involving formation of the active six-coordinate Mn3+ and proton transfer from a second-sphere water molecule, which has substituted for the ─OH of Tyr34, to the Mn-peroxo complex. Because WT and the mutant yeast MnSOD both rest in the 2+ state and become six-coordinate when oxidized up from Mn2+, six-coordinate Mn3+ species could also actively function in the mechanism of WT yeast MnSODs. PMID:22908245

  20. FUNCTIONAL CHARACTERIZATION AND EXPRESSION ANALYSIS OF THE ZIP1 METAL TRANSPORTER IN MEDICAGO TRUNCATULA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The family of transporters in plants that has sequence similarity to the ZRT and IRT transporters in Saccharomyces cerevisiae is referred to as the ZIP gene family. These genes encode for proteins that have been shown to transport divalent cations such as zinc, iron and manganese. The ZIP1 gene in M...

  1. Sorption of ferric iron from ferrioxamine B to synthetic and biogenic layer type manganese oxides

    NASA Astrophysics Data System (ADS)

    Duckworth, Owen W.; Bargar, John R.; Sposito, Garrison

    2008-07-01

    Siderophores are biogenic chelating agents produced in terrestrial and marine environments that increase the bioavailability of ferric iron. Recent work has suggested that both aqueous and solid-phase Mn(III) may affect siderophore-mediated iron transport, but scant information appears to be available about the potential roles of layer type manganese oxides, which are relatively abundant in soils and the oligotrophic marine water column. To probe the effects of layer type manganese oxides on the stability of aqueous Fe-siderophore complexes, we studied the sorption of ferrioxamine B [Fe(III)HDFOB +, an Fe(III) chelate of the trihydroxamate siderophore desferrioxamine B (DFOB)] to two synthetic birnessites [layer type Mn(III,IV) oxides] and a biogenic birnessite produced by Pseudomonas putida GB-1. We found that all of these predominantly Mn(IV) oxides greatly reduced the aqueous concentration of Fe(III)HDFOB + at pH 8. Analysis of Fe K-edge EXAFS spectra indicated that a dominant fraction of Fe(III) associated with the Mn(IV) oxides is not complexed by DFOB as in solution, but instead Fe(III) is specifically adsorbed to the mineral structure at multiple sites, thus indicating that the Mn(IV) oxides displaced Fe(III) from the siderophore complex. These results indicate that layer type manganese oxides, including biogenic minerals, may sequester iron from soluble ferric complexes. We conclude that the sorption of iron-siderophore complexes may play a significant role in the bioavailability and biogeochemical cycling of iron in marine and terrestrial environments.

  2. Manganese superoxide dismutase: guardian of the powerhouse.

    PubMed

    Holley, Aaron K; Bakthavatchalu, Vasudevan; Velez-Roman, Joyce M; St Clair, Daret K

    2011-01-01

    The mitochondrion is vital for many metabolic pathways in the cell, contributing all or important constituent enzymes for diverse functions such as β-oxidation of fatty acids, the urea cycle, the citric acid cycle, and ATP synthesis. The mitochondrion is also a major site of reactive oxygen species (ROS) production in the cell. Aberrant production of mitochondrial ROS can have dramatic effects on cellular function, in part, due to oxidative modification of key metabolic proteins localized in the mitochondrion. The cell is equipped with myriad antioxidant enzyme systems to combat deleterious ROS production in mitochondria, with the mitochondrial antioxidant enzyme manganese superoxide dismutase (MnSOD) acting as the chief ROS scavenging enzyme in the cell. Factors that affect the expression and/or the activity of MnSOD, resulting in diminished antioxidant capacity of the cell, can have extraordinary consequences on the overall health of the cell by altering mitochondrial metabolic function, leading to the development and progression of numerous diseases. A better understanding of the mechanisms by which MnSOD protects cells from the harmful effects of overproduction of ROS, in particular, the effects of ROS on mitochondrial metabolic enzymes, may contribute to the development of novel treatments for various diseases in which ROS are an important component. PMID:22072939

  3. Redundancy among manganese peroxidases in Pleurotus ostreatus.

    PubMed

    Salame, Tomer M; Knop, Doriv; Levinson, Dana; Yarden, Oded; Hadar, Yitzhak

    2013-04-01

    Manganese peroxidases (MnPs) are key players in the ligninolytic system of white rot fungi. In Pleurotus ostreatus (the oyster mushroom) these enzymes are encoded by a gene family comprising nine members, mnp1 to -9 (mnp genes). Mn(2+) amendment to P. ostreatus cultures results in enhanced degradation of recalcitrant compounds (such as the azo dye orange II) and lignin. In Mn(2+)-amended glucose-peptone medium, mnp3, mnp4, and mnp9 were the most highly expressed mnp genes. After 7 days of incubation, the time point at which the greatest capacity for orange II decolorization was observed, mnp3 expression and the presence of MnP3 in the extracellular culture fluids were predominant. To determine the significance of MnP3 for ligninolytic functionality in Mn(2+)-sufficient cultures, mnp3 was inactivated via the Δku80 strain-based P. ostreatus gene-targeting system. In Mn(2+)-sufficient medium, inactivation of mnp3 did not significantly affect expression of nontargeted MnPs or their genes, nor did it considerably diminish the fungal Mn(2+)-mediated orange II decolorization capacity, despite the significant reduction in total MnP activity. Similarly, inactivation of either mnp4 or mnp9 did not affect orange II decolorization ability. These results indicate functional redundancy within the P. ostreatus MnP gene family, enabling compensation upon deficiency of one of its members. PMID:23377936

  4. Elemental Abundances of Mercury-Manganese Stars

    NASA Astrophysics Data System (ADS)

    Adelman, Saul J.

    We propose to obtain a carefully planned set of multiple high dispersion exposures of three MercuryManganese stars in both the SWP and LWP cameras. These observations will be coadded to increase the S/N ratio so that accurate elemental abundances can be derived for these examples of HgMn stars, each of which represents some extreme class aspect. This will increase of sample of HgMn stars from four to seven. Of particular interest are the abundances of N and Co in which some HgMn stars have shown remarkable underabundances. Comparison of the UV and optical spectra features due to light elements such as N (and C and 0) provide an observational framework to test NLTE models such as those of Takada (1993). This work has already shed some light on some of earlier findings for normal stars. The ability to accurately determine the surface chemical composition of the late B stars through such studies will lead to better tests for theories purporting to explain the origin of the chemical peculiarities seen in this temperature domain.

  5. Redundancy among Manganese Peroxidases in Pleurotus ostreatus

    PubMed Central

    Salame, Tomer M.; Knop, Doriv; Levinson, Dana; Yarden, Oded

    2013-01-01

    Manganese peroxidases (MnPs) are key players in the ligninolytic system of white rot fungi. In Pleurotus ostreatus (the oyster mushroom) these enzymes are encoded by a gene family comprising nine members, mnp1 to -9 (mnp genes). Mn2+ amendment to P. ostreatus cultures results in enhanced degradation of recalcitrant compounds (such as the azo dye orange II) and lignin. In Mn2+-amended glucose-peptone medium, mnp3, mnp4, and mnp9 were the most highly expressed mnp genes. After 7 days of incubation, the time point at which the greatest capacity for orange II decolorization was observed, mnp3 expression and the presence of MnP3 in the extracellular culture fluids were predominant. To determine the significance of MnP3 for ligninolytic functionality in Mn2+-sufficient cultures, mnp3 was inactivated via the Δku80 strain-based P. ostreatus gene-targeting system. In Mn2+-sufficient medium, inactivation of mnp3 did not significantly affect expression of nontargeted MnPs or their genes, nor did it considerably diminish the fungal Mn2+-mediated orange II decolorization capacity, despite the significant reduction in total MnP activity. Similarly, inactivation of either mnp4 or mnp9 did not affect orange II decolorization ability. These results indicate functional redundancy within the P. ostreatus MnP gene family, enabling compensation upon deficiency of one of its members. PMID:23377936

  6. Genetic factors and manganese-induced neurotoxicity

    PubMed Central

    Chen, Pan; Parmalee, Nancy; Aschner, Michael

    2014-01-01

    Manganese (Mn), is a trace metal required for normal physiological processes in humans. Mn levels are tightly regulated, as high levels of Mn result in accumulation in the brain and cause a neurological disease known as manganism. Manganism shares many similarities with Parkinson’s disease (PD), both at the physiological level and the cellular level. Exposure to high Mn-containing environments increases the risk of developing manganism. Mn is absorbed primarily through the intestine and then released in the blood. Excessive Mn is secreted in the bile and excreted in feces. Mn enters and exits cells through a number of non-specific importers localized on the cell membrane. Mutations in one of the Mn exporters, SLC30A10 (solute carrier family 30, member 10), result in Mn induced toxicity with liver impairments and neurological dysfunction. Four PD genes have been identified in connection to regulation of Mn toxicity, shedding new light on potential links between manganism and PD. PMID:25136353

  7. Oxidation kinetics of pentachlorophenol by manganese dioxide.

    PubMed

    Zhao, Ling; Yu, Zhiqiang; Peng, Pingán; Huang, Weilin; Feng, Shunqing; Zhou, Haiyan

    2006-11-01

    This study examined the abiotic transformation kinetics of pentachlorophenol (PCP) by manganese dioxide (MnO2) at different solution chemistry and initial concentrations of PCP and MnO2. The measured PCP transformation rates were found to be on the order of 1.07 with respect to [PCP] and 0.91 and 0.87 with respect to [MnO2] and [H+], respectively. Dissolved Mn2+ and Ca2+ as background electrolytes considerably decreased the reaction rate because of their adsorption and hence blocking of active sites on MnO2 surfaces. The dechlorination number, 0.59 chloride ions per transformed PCP after a 1-h reaction, suggests that a fraction of the transformed PCP was not dechlorinated and may be coupled directly to dimeric products. Gas chromatography/ mass spectrometry and liquid chromatography/mass spectrometry/mass spectrometry techniques were used to identify two isomeric nonachlorohydroxybiphenylethers as major products and 2,3,5,6-tetrachloro-1,4-hydroquinone and tetrachlorocatechol as minor products. Product identification suggested that the reaction may include two parallel reactions to form either dimers or 2,3,5,6-tetrachloro-1,4-hydroquinone and tetrachlorocatechol via simultaneous dehydrochlorination and hydroxylation. PMID:17089714

  8. Manganese Superoxide Dismutase: Guardian of the Powerhouse

    PubMed Central

    Holley, Aaron K.; Bakthavatchalu, Vasudevan; Velez-Roman, Joyce M.; St. Clair, Daret K.

    2011-01-01

    The mitochondrion is vital for many metabolic pathways in the cell, contributing all or important constituent enzymes for diverse functions such as β-oxidation of fatty acids, the urea cycle, the citric acid cycle, and ATP synthesis. The mitochondrion is also a major site of reactive oxygen species (ROS) production in the cell. Aberrant production of mitochondrial ROS can have dramatic effects on cellular function, in part, due to oxidative modification of key metabolic proteins localized in the mitochondrion. The cell is equipped with myriad antioxidant enzyme systems to combat deleterious ROS production in mitochondria, with the mitochondrial antioxidant enzyme manganese superoxide dismutase (MnSOD) acting as the chief ROS scavenging enzyme in the cell. Factors that affect the expression and/or the activity of MnSOD, resulting in diminished antioxidant capacity of the cell, can have extraordinary consequences on the overall health of the cell by altering mitochondrial metabolic function, leading to the development and progression of numerous diseases. A better understanding of the mechanisms by which MnSOD protects cells from the harmful effects of overproduction of ROS, in particular, the effects of ROS on mitochondrial metabolic enzymes, may contribute to the development of novel treatments for various diseases in which ROS are an important component. PMID:22072939

  9. Effects of manganese on the microstructures of Chenopodium ambrosioides L., A manganese tolerant plant.

    PubMed

    Xue, Shengguo; Zhu, Feng; Wu, Chuan; Lei, Jie; Hartley, William; Pan, Weisong

    2016-07-01

    Chenopodium ambrosioides L. can tolerate high concentrations of manganese and has potential for its use in the revegetation of manganese mine tailings. Following a hydroponic investigation, transmission electron microscopy (TEM)-energy disperse spectroscopy (EDS) was used to study microstructure changes and the possible accumulation of Mn in leaf cells of C. ambrosioides in different Mn treatments (200, 1000, 10000 μmol·L(-1)). At 200 μmol·L(-1), the ultrastructure of C. ambrosioides was clearly visible without any obvious damage. At 1000 μmol·L(-1), the root, stem and leaf cells remained intact, and the organelles were clearly visible without any obvious damage. However, when the Mn concentration exceeded 1000 μmol·L(-1) the number of mitochondria in root cells decreased and the chloroplasts in stem cells showed a decrease in grana lamellae and osmiophilic granules. Compared to controls, treatment with 1000 μmol·L(-1) or 10000 μmol·L(-1) Mn over 30 days, gave rise to black agglomerations in the cells. At 10000 μmol·L(-1), Mn was observed to form acicular structures in leaf cells and intercellular spaces, which may be a form of tolerance and accumulation of Mn in C. ambrosioides. This study has furthered the understanding of Mn tolerance mechanisms in plants, and is potential for the revegetation of Mn-polluted soils. PMID:26696389

  10. Manganese and acute paranoid psychosis: a case report

    PubMed Central

    2011-01-01

    Introduction Manganese regulates many enzymes and is essential for normal development and body function. Chronic manganese intoxication has an insidious and progressive course and usually starts with complaints of headache, fatigue, sleep disturbances, irritability and emotional instability. Later, several organ systems may be affected and, due to neurotoxicity, an atypical parkinsonian syndrome may emerge. With regard to neuropsychiatry, an array of symptoms may develop up to 30 years after intoxication, of which gait and speech abnormalities, cognitive and motor slowing, mood changes and hallucinations are the most common. Psychotic phenomena are rarely reported. Case presentation We describe the case of a 49-year-old Caucasian man working as a welder who was referred to our facility for evaluation of acute paranoid psychotic behavior. Our patient's medical history made no mention of any somatic complaints or psychiatric symptoms, and he had been involved in a professional career as a metalworker. On magnetic resonance imaging scanning of his brain, a bilateral hyperdensity of the globus pallidus, suggestive for manganese intoxication, was found. His manganese serum level was 52 to 97 nmol/L (range: 7 to 20 nmol/L). A diagnosis of organic psychotic disorder due to manganese overexposure was made. His psychotic symptoms disappeared within two weeks of treatment with low-dose risperidone. At three months later, serum manganese was decreased to slightly elevated levels and the magnetic resonance imaging T1 signal intensity was reduced. No signs of Parkinsonism were found and a definite diagnosis of manganese-induced apathy syndrome was made. Conclusion Although neuropsychiatric and neurological symptoms caused by (chronic) manganese exposure have been reported frequently in the past, in the present day the disorder is rarely diagnosed. In this report we stress that manganese intoxication can still occur, in our case in a confined-space welder, and may present

  11. 69 FR 11040 - Electrolytic Manganese Dioxide From Australia, Greece, Ireland, Japan, and South Africa

    Federal Register 2010, 2011, 2012, 2013, 2014

    2004-03-09

    ... COMMISSION Electrolytic Manganese Dioxide From Australia, Greece, Ireland, Japan, and South Africa AGENCY... terminating its antidumping investigations on electrolytic manganese dioxide from Australia, Greece, Ireland... dioxide from Australia, Greece, Ireland, Japan, and South Africa (investigations Nos. 731-TA-1048 and...

  12. 65 FR 12575 - Electrolytic Manganese Dioxide From Greece and Japan; Notice of Commission Determination To...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2000-03-09

    ... From the Federal Register Online via the Government Publishing Office INTERNATIONAL TRADE COMMISSION Electrolytic Manganese Dioxide From Greece and Japan; Notice of Commission Determination To..., a portion of the Commission's hearing in Electrolytic Manganese Dioxide from Greece and Japan,...

  13. Manganese and epilepsy: a systematic review of the literature.

    PubMed

    Gonzalez-Reyes, Rodrigo E; Gutierrez-Alvarez, Angela M; Moreno, Carlos B

    2007-02-01

    Manganese is an essential trace element for the development and function of the central nervous system. Alterations in manganese concentrations, whether excessive or deficient, can be accompanied by convulsions. This article represents a systematic review of available quantitative evidence that might clarify this issue. We searched The Cochrane Library, Medline and LILACS databases from January 1966 through June 2006 and reviewed all resulting English and Spanish language publications, as well as those possibly relevant in other languages based on their abstracts. The final selection included for this review comprises all investigations in humans and animals that compared manganese levels in any tissue of a group with spontaneous or induced convulsions (with or without antiepileptic treatment) and a convulsion-free control group. The literature search identified thirteen publications since then relevant to the issue, four of which failed to meet our criteria for inclusion. Of the remaining nine, six were in humans and three in rodents. At present, there is no satisfactory explanation for the relationship between low manganese levels and the presence of convulsions. There is a documented correlation between low blood manganese levels and the presence of convulsions in both humans and animals. The lack of evidence indicating whether this is a cause or an effect of the convulsions clearly justifies more detailed follow-up investigations in humans. PMID:17166592

  14. Motoric impairment following manganese exposure in asteroid echinoderms.

    PubMed

    Sköld, Helen Nilsson; Baden, Susanne P; Looström, Jakob; Eriksson, Susanne P; Hernroth, Bodil E

    2015-10-01

    In the oceans, naturally occurring manganese (Mn) is released from the sediments during events of hypoxia. While neuro- and immuno-toxic effects of bioavailable manganese are well documented for crustaceans, studies of similar effects of manganese on other marine invertebrates are comparatively few. Here, we developed a new functional test "the repeated turning assay" to investigate if manganese exposure at ∼12 mg L(-1) affected motoric behaviour of two asteroid echinoderms, the Common sea star, Asterias rubens, and the Black brittle star, Ophiocomina nigra. By measuring of the turning-over capacity, from dorsal to ventral position, after one and two weeks of manganese exposure, we showed that for both species Mn exposure significantly delayed the ability to turn. After a recovery period of two weeks, the capacity of turning-over was not restored to that of unexposed animals neither for A. rubens nor for O. nigra. Further investigation of sea stars showed that Mn accumulated ∼5 fold in the tube feet, organs involved in their turning-over activity, and the high concentration remained after the recovery period. In the tube feet we also recorded an increased activity of acetylcholinesterase (AChE), here used as a proxy for neuromuscular disturbances. The results indicated that Mn induces neuromuscular disturbance in echinoderms which is important news, given that previous studies have concluded that adult echinoderms are relatively tolerant to Mn. PMID:26254768

  15. Occupational asthma due to manganese exposure: a case report.

    PubMed

    Wittczak, Tomasz; Dudek, Wojciech; Krakowiak, Anna; Walusiak, Jolanta; Pałczyński, Cezary

    2008-01-01

    Manganese belongs to a group of agents called "transitional metals" that are known to induce occupational asthma. However, well-documented cases of manganese-induced asthma have been lacking thus far. We have discussed a case of a 42-year-old non-smoking welder with work-related dyspnea. A number of clinical procedures were performed including clinical examination, routine laboratory tests, total serum IgE, skin prick tests to common aeroallergens and manganese nitrate, resting spirometry test, histamine challenge, and a single-blind, placebo-controlled specific inhalation challenge with 0.1% manganese chloride solution. Clinical findings and laboratory test results remained normal but a significant bronchial hyperreactivity was found. During the specific inhalation challenge, dyspnea and a significant decrease in forced expiratory volume (FEV1) were observed. An increased proportion of eosinophils and basophils in induced sputum could also be noted at 4 and 24 h after the challenge. The argument for recognizing the condition as occupational asthma was a positive clinical response to the specific challenge test as well as the morphological changes found in induced sputum. To our knowledge, this is the first well-documented case of manganese-induced occupational asthma. PMID:18468975

  16. Manganese tolerance in yeasts involves polyphosphate, magnesium, and vacuolar alterations.

    PubMed

    Ryazanova, Lubov; Zvonarev, Anton; Rusakova, Tatiana; Dmitriev, Vladimir; Kulakovskaya, Tatiana

    2016-07-01

    Basidiomycetous and ascomycetous yeast species were tested for manganese tolerance. Basidiomycetous Cryptococcus humicola, Cryptococcus terricola, Cryptococcus curvatus and ascomycetous Candida maltosa, Kluyveromyces marxianus, Kuraishia capsulata, Lindnera fabianii and Sacharomyces cerevisiae were able to grow at manganese excess (2.5 mmol/L), while the growth of basidiomycetous Rhodotorula bogoriensis was completely suppressed. The lag phase duration increased and the exponential growth rate decreased at manganese excess. The increase of cell size and enlargement of vacuoles were characteristics for the cells grown at manganese excess. The alterations in inorganic polyphosphate content and cellular localization were studied. L. fabianii, K. capsulata, C. maltosa, and Cr. humicola accumulated the higher amounts of inorganic polyphosphates, while Cr. terricola and Cr. curvatus demonstrated no such accumulation. The polyphosphate content in the cell wall tested by DAPI staining increased in all species under the study; however, this effect was more pronounced in Cr. terricola and Cr. curvatus. The accumulation of Mg(2+) in the cell wall under Mn(2+) excess was observed in Cr. humicola, Cr. curvatus and Cr. terricola. The accumulation of polyphosphate and magnesium in the cell wall was supposed to be a factor of manganese tolerance in yeasts. PMID:26646947

  17. The sorption of silver by poorly crystallized manganese oxides

    USGS Publications Warehouse

    Anderson, B.J.; Jenne, E.A.; Chao, T.T.

    1973-01-01

    The sorption of silver by poorly crystallized manganese oxides was studied using synthesized samples of three members of the manganous manganite (birnessite) group, of different chemical composition and crystallinity, and a poorly organized ??-MnO2. All four oxides sorbed significant quantities of silver. The manganous manganites showed the greatest sorption (up to 0.5 moles silver/mole MnOx at pH 7) while the ??-MnO2 showed the least (0.3 moles silver/ mole MnOx at pH 7). Sorption of silver was adequately described by the Langmuir equation over a considerable concentration range. The relationship failed at low pH values and high equilibrium silver concentrations. The sorption capacity showed a direct relationship with pH. However, the rate of increase of sorption capacity decreased at the higher pH values. Silver sorption maxima. were not directly related to surface area but appeared to vary with the amount of occluded sodium and potassium present in the manganese oxide. The important processes involved in the uptake of silver by the four poorly crystallized manganese oxides ara considered to be surface exchange for manganese, potassium and sodium as well as exchange for structural manganese, potassium and sodium. ?? 1973.

  18. Brain uptake, retention, and efflux of aluminum and manganese.

    PubMed Central

    Yokel, Robert A

    2002-01-01

    My colleagues and I investigated the sites and mechanisms of aluminum (Al) and manganese (Mn) distribution through the blood-brain barrier (BBB). Microdialysis was used to sample non-protein-bound Al in the extracellular fluid (ECF) of blood (plasma) and brain. Brain ECF Al appearance after intravenous Al citrate injection was too rapid to attribute to diffusion or to transferrin-receptor-mediated endocytosis, suggesting another carrier-mediated process. The brain:blood ECF Al concentration ratio was 0.15 at constant blood and brain ECF Al concentrations, suggesting carrier-mediated brain Al efflux. Pharmacological manipulations suggested the efflux carrier might be a monocarboxylate transporter (MCT). However, the lack of Al (14)C-citrate uptake into rat erythrocytes suggested it is not a good substrate for isoform MCT1 or for the band 3 anion exchanger. Al (14)C-citrate uptake into murine-derived brain endothelial cells appeared to be carrier mediated, Na independent, pH independent, and energy dependent. Uptake was inhibited by substrate/inhibitors of the MCT and organic anion transporter families. Determination of (26)Al in rat brain at various times after intravenous (26)Al suggested a prolonged brain (26)Al half-life. It appears that Al transferrin and Al citrate cross the BBB by different mechanisms, that much of the Al entering brain ECF is rapidly effluxed, probably as Al citrate, but that some Al is retained for quite some time. Brain influx of the Mn(2+) ion and Mn citrate, determined with the in situ brain perfusion technique, was greater than that attributable to diffusion, suggesting carrier-mediated uptake. Mn citrate uptake was approximately 3-fold greater than the Mn(2+) ion, suggesting it is a primary Mn species entering the brain. After Mn(2+) ion, Mn citrate, or Mn transferrin injection into the brain, brain Mn efflux was not more rapid than that predicted from diffusion. The BBB permeation of Al and Mn is mediated by carriers that may help

  19. Treponema denticola TroR is a manganese- and iron-dependent transcriptional repressor

    PubMed Central

    Brett, Paul J; Burtnick, Mary N; Fenno, J Christopher; Gherardini, Frank C

    2008-01-01

    Treponema denticola harbours a genetic locus with significant homology to most of the previously characterized Treponema pallidum tro operon. Within this locus are five genes (troABCDR) encoding for the components of an ATP-binding cassette cation-transport system (troABCD) and a DtxR-like transcriptional regulator (troR). In addition, a σ70-like promoter and an 18 bp region of dyad symmetry were identified upstream of the troA start codon. This putative operator sequence demonstrated similarity to the T. pallidum TroR (TroRTp) binding sequence; however, the position of this motif with respect to the predicted tro promoters differed. Interestingly, unlike the T. pallidum orthologue, T. denticola TroR (TroRTd) possesses a C-terminal Src homology 3-like domain commonly associated with DtxR family members. In the present study, we show that TroRTd is a manganese- and iron-dependent transcriptional repressor using Escherichia coli reporter constructs and in T. denticola. In addition, we demonstrate that although TroRTd possessing various C-terminal deletions maintain metal-sensing capacities, these truncated proteins exhibit reduced repressor activities in comparison with full-length TroRTd. Based upon these findings, we propose that TroRTd represents a novel member of the DtxR family of transcriptional regulators and is likely to play an important role in regulating both manganese and iron homeostases in this spirochaete. PMID:18761626

  20. Imaging corticospinal tract connectivity in injured rat spinal cord using manganese-enhanced MRI

    PubMed Central

    Bilgen, Mehmet

    2006-01-01

    Background Manganese-enhanced MRI (MEI) offers a novel neuroimaging modality to trace corticospinal tract (CST) in live animals. This paper expands this capability further and tests the utility of MEI to image axonal fiber connectivity in CST of injured spinal cord (SC). Methods A rat was injured at the thoracic T4 level of the SC. The CST was labeled with manganese (Mn) injected intracortically at two weeks post injury. Next day, the injured SC was imaged using MEI and diffusion tensor imaging (DTI) modalities. Results In vivo MEI data obtained from cervical SC confirmed that CST was successfully labeled with Mn. Ex vivo MEI data obtained from excised SC depicted Mn labeling of the CST in SC sections caudal to the lesion, which meant that Mn was transported through the injury, possibly mediated by viable CST fibers present at the injury site. Examining the ex vivo data from the injury epicenter closely revealed a thin strip of signal enhancement located ventrally between the dorsal horns. This enhancement was presumably associated with the Mn accumulation in these intact fibers projecting caudally as part of the CST. Additional measurements with DTI supported this view. Conclusion Combining these preliminary results collectively demonstrated the feasibility of imaging fiber connectivity in experimentally injured SC using MEI. This approach may play important role in future investigations aimed at understanding the neuroplasticity in experimental SCI research. PMID:17112375

  1. Analysis of numerical simulations and influencing factors of seasonal manganese pollution in reservoirs.

    PubMed

    Peng, Hui; Zheng, Xilai; Chen, Lei; Wei, Yang

    2016-07-01

    Seasonal manganese pollution has become an increasingly pressing water quality issue for water supply reservoirs in recent years. Manganese is a redox-sensitive element and is released from sediment under anoxic conditions near the sediment-water interface during summer and autumn, when water temperature stratification occurs. The reservoir water temperature and water dynamic conditions directly influence the formation of manganese pollution. Numerical models are useful tools to quantitatively evaluate manganese pollution and its influencing factors. This paper presents a reservoir manganese pollution model by adding a manganese biogeochemical module to a water quality model-CE-QUAL-W2. The model is applied to the Wangjuan reservoir (Qingdao, China), which experiences manganese pollution during summer and autumn. Field data are used to verify the model, and the results show that the model can reproduce the main features of the thermal stratification and manganese distribution. The model is used to evaluate the manganese pollution process and its four influencing factors, including air temperature, water level, wind speed, and wind directions, through different simulation scenarios. The results show that all four factors can influence manganese pollution. High air temperature, high water level, and low wind speed aggravate manganese pollution, while low air temperature, low water level, and high wind speed reduce manganese pollution. Wind that travels in the opposite direction of the flow aggravates manganese pollution, while wind in the same direction as the flow reduces manganese pollution. This study provides useful information to improve our understanding of seasonal manganese pollution in reservoirs, which is important for reservoir manganese pollution warnings and control. PMID:27068892

  2. The Evolutionarily Conserved Protein PHOTOSYNTHESIS AFFECTED MUTANT71 Is Required for Efficient Manganese Uptake at the Thylakoid Membrane in Arabidopsis.

    PubMed

    Schneider, Anja; Steinberger, Iris; Herdean, Andrei; Gandini, Chiara; Eisenhut, Marion; Kurz, Samantha; Morper, Anna; Hoecker, Natalie; Rühle, Thilo; Labs, Mathias; Flügge, Ulf-Ingo; Geimer, Stefan; Schmidt, Sidsel Birkelund; Husted, Søren; Weber, Andreas P M; Spetea, Cornelia; Leister, Dario

    2016-04-01

    In plants, algae, and cyanobacteria, photosystem II (PSII) catalyzes the light-driven oxidation of water. The oxygen-evolving complex of PSII is a Mn4CaO5 cluster embedded in a well-defined protein environment in the thylakoid membrane. However, transport of manganese and calcium into the thylakoid lumen remains poorly understood. Here, we show that Arabidopsis thaliana PHOTOSYNTHESIS AFFECTED MUTANT71 (PAM71) is an integral thylakoid membrane protein involved in Mn(2+) and Ca(2+) homeostasis in chloroplasts. This protein is required for normal operation of the oxygen-evolving complex (as evidenced by oxygen evolution rates) and for manganese incorporation. Manganese binding to PSII was severely reduced in pam71 thylakoids, particularly in PSII supercomplexes. In cation partitioning assays with intact chloroplasts, Mn(2+) and Ca(2+) ions were differently sequestered in pam71, with Ca(2+) enriched in pam71 thylakoids relative to the wild type. The changes in Ca(2+) homeostasis were accompanied by an increased contribution of the transmembrane electrical potential to the proton motive force across the thylakoid membrane. PSII activity in pam71 plants and the corresponding Chlamydomonas reinhardtii mutant cgld1 was restored by supplementation with Mn(2+), but not Ca(2+) Furthermore, PAM71 suppressed the Mn(2+)-sensitive phenotype of the yeast mutant Δpmr1 Therefore, PAM71 presumably functions in Mn(2+) uptake into thylakoids to ensure optimal PSII performance. PMID:27020959

  3. Manganese superoxide dismutase: beyond life and death

    PubMed Central

    Holley, Aaron K.; Dhar, Sanjit Kumar; Xu, Yong

    2010-01-01

    Manganese superoxide dismutase (MnSOD) is a nuclear-encoded antioxidant enzyme that localizes to the mitochondria. Expression of MnSOD is essential for the survival of aerobic life. Transgenic mice expressing a luciferase reporter gene under the control of the human MnSOD promoter demonstrate that the level of MnSOD is reduced prior to the formation of cancer. Overexpression of MnSOD in transgenic mice reduces the incidences and multiplicity of papillomas in a DMBA/TPA skin carcinogenesis model. However, MnSOD deficiency does not lead to enhanced tumorigenicity of skin tissue similarly treated because MnSOD can modulate both the p53-mediated apoptosis and AP-1-mediated cell proliferation pathways. Apoptosis is associated with an increase in mitochondrial levels of p53 suggesting a link between MnSOD deficiency and mitochondrial-mediated apoptosis. Activation of p53 is preventable by application of a SOD mimetic (MnTE-2-PyP5+). Thus, p53 translocation to mitochondria and subsequent inactivation of MnSOD explain the observed mitochondrial dysfunction that leads to transcription-dependent mechanisms of p53-induced apoptosis. Administration of MnTE-2-PyP5+ following apoptosis but prior to proliferation leads to suppression of protein carbonyls and reduces the activity of AP-1 and the level of the proliferating cellular nuclear antigen, without reducing the activity of p53 or DNA fragmentation following TPA treatment. Remarkably, the incidence and multiplicity of skin tumors are drastically reduced in mice that receive MnTE-2-PyP5+ prior to cell proliferation. The results demonstrate the role of MnSOD beyond its essential role for survival and suggest a novel strategy for an antioxidant approach to cancer intervention. PMID:20454814

  4. Manganese and the Evolution of Photosynthesis

    NASA Astrophysics Data System (ADS)

    Fischer, Woodward W.; Hemp, James; Johnson, Jena E.

    2015-09-01

    Oxygenic photosynthesis is the most important bioenergetic event in the history of our planet—it evolved once within the Cyanobacteria, and remained largely unchanged as it was transferred to algae and plants via endosymbiosis. Manganese plays a fundamental role in this history because it lends the critical redox behavior of the water-oxidizing complex of photosystem II. Constraints from the photoassembly of the Mn-bearing water-oxidizing complex fuel the hypothesis that Mn(II) once played a key role as an electron donor for anoxygenic photosynthesis prior to the evolution of oxygenic photosynthesis. Here we review the growing body of geological and geochemical evidence from the Archean and Paleoproterozoic sedimentary records that supports this idea and demonstrates that the oxidative branch of the Mn cycle switched on prior to the rise of oxygen. This Mn-oxidizing phototrophy hypothesis also receives support from the biological record of extant phototrophs, and can be made more explicit by leveraging constraints from structural biology and biochemistry of photosystem II in Cyanobacteria. These observations highlight that water-splitting in photosystem II evolved independently from a homodimeric ancestral type II reaction center capable of high potential photosynthesis and Mn(II) oxidation, which is required by the presence of homologous redox-active tyrosines in the modern heterodimer. The ancestral homodimer reaction center also evolved a C-terminal extension that sterically precluded standard phototrophic electron donors like cytochrome c, cupredoxins, or high-potential iron-sulfur proteins, and could only complete direct oxidation of small molecules like Mn2+, and ultimately water.

  5. Hyperspectral characteristics of Celosia argentea which lived in manganese stress environment and inversion model for concentration effect of manganese

    NASA Astrophysics Data System (ADS)

    Chen, Sanming; Lin, Gang; Yin, Xianyang; Sun, Xiaolin; Xu, Jiasheng; Liu, Zhiying

    2015-12-01

    Sedimentary manganese deposits widely distribute in North Guangxi with the characteristic existing Celosia argentea. Celosia argentea is a kind of plant which has a strong ability to enrich manganese. In order to study the relationship between the hyperspectral characteristics of Celosia argentea and the concentration effect of manganese in the soil, we used soil of B layer in mining area, background soil and the soil adding reagent of MnCl4 to make up experimental sample soil with 10 levels Manganese content for the same batch Celosia argentea. The levels are 0mg/kg, 4500mg/kg, 9000mg/kg, 13500mg/kg, 18000mg/kg, 18020mg/kg, 18040mg/kg, 18080mg/kg, 18160mg/kg. ASD FieldSpec-4 has been used to measure the abnormal spectrums of these Celosia argentea through a whole growth cycle. After pretreating the spectral data, we used Successive Projections Algorithm (SPA) to extract the characteristic variables for extracting 1603 bands into 8 bands. Finally, the relationship between the spectral variables and the concentration of manganese was predicted by the Model of Partial Least Squares Regression (PLSR). The results show that the correlation coefficient-r2 are 0.8714 and 0.9141 in two sets of data. The prediction results are satisfactory, but the front 5 groups are closer to the regression line than the last 5 groups.

  6. 40 CFR 721.10529 - Cobalt iron manganese oxide, carboxylic acid-modified (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Cobalt iron manganese oxide... Significant New Uses for Specific Chemical Substances § 721.10529 Cobalt iron manganese oxide, carboxylic acid... substance identified generically as cobalt iron manganese oxide, carboxylic acid-modified (PMN P-12-35)...

  7. 40 CFR 721.10529 - Cobalt iron manganese oxide, carboxylic acid-modified (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Cobalt iron manganese oxide... Significant New Uses for Specific Chemical Substances § 721.10529 Cobalt iron manganese oxide, carboxylic acid... substance identified generically as cobalt iron manganese oxide, carboxylic acid-modified (PMN P-12-35)...

  8. 40 CFR 721.10222 - Styrenyl surface treated manganese ferrite (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Styrenyl surface treated manganese... Specific Chemical Substances § 721.10222 Styrenyl surface treated manganese ferrite (generic). (a) Chemical... as styrenyl surface treated manganese ferrite (PMN P-09-581) is subject to reporting under...

  9. 40 CFR 721.10222 - Styrenyl surface treated manganese ferrite (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Styrenyl surface treated manganese... Specific Chemical Substances § 721.10222 Styrenyl surface treated manganese ferrite (generic). (a) Chemical... as styrenyl surface treated manganese ferrite (PMN P-09-581) is subject to reporting under...

  10. 40 CFR 721.10222 - Styrenyl surface treated manganese ferrite (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Styrenyl surface treated manganese... Specific Chemical Substances § 721.10222 Styrenyl surface treated manganese ferrite (generic). (a) Chemical... as styrenyl surface treated manganese ferrite (PMN P-09-581) is subject to reporting under...

  11. 40 CFR 721.4587 - Lithium manganese oxide (LiMn204) (generic name).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Lithium manganese oxide (LiMn204... Specific Chemical Substances § 721.4587 Lithium manganese oxide (LiMn204) (generic name). (a) Chemical... as lithium manganese oxide (LiMn204) (P-96-175) is subject to reporting under this section for...

  12. 40 CFR 721.4587 - Lithium manganese oxide (LiMn204) (generic name).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Lithium manganese oxide (LiMn204... Specific Chemical Substances § 721.4587 Lithium manganese oxide (LiMn204) (generic name). (a) Chemical... as lithium manganese oxide (LiMn204) (P-96-175) is subject to reporting under this section for...

  13. 40 CFR 721.4587 - Lithium manganese oxide (LiMn204) (generic name).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Lithium manganese oxide (LiMn204... Specific Chemical Substances § 721.4587 Lithium manganese oxide (LiMn204) (generic name). (a) Chemical... as lithium manganese oxide (LiMn204) (P-96-175) is subject to reporting under this section for...

  14. 40 CFR 721.4587 - Lithium manganese oxide (LiMn204) (generic name).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Lithium manganese oxide (LiMn204... Specific Chemical Substances § 721.4587 Lithium manganese oxide (LiMn204) (generic name). (a) Chemical... as lithium manganese oxide (LiMn204) (P-96-175) is subject to reporting under this section for...

  15. 40 CFR 721.4587 - Lithium manganese oxide (LiMn204) (generic name).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Lithium manganese oxide (LiMn204... Specific Chemical Substances § 721.4587 Lithium manganese oxide (LiMn204) (generic name). (a) Chemical... as lithium manganese oxide (LiMn204) (P-96-175) is subject to reporting under this section for...

  16. 40 CFR 721.10008 - Manganese strontium oxide (MnSrO3).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Manganese strontium oxide (MnSrO3... Specific Chemical Substances § 721.10008 Manganese strontium oxide (MnSrO3). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as manganese strontium...

  17. 40 CFR 721.10008 - Manganese strontium oxide (MnSrO3).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Manganese strontium oxide (MnSrO3... Specific Chemical Substances § 721.10008 Manganese strontium oxide (MnSrO3). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as manganese strontium...

  18. 40 CFR 721.10008 - Manganese strontium oxide (MnSrO3).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Manganese strontium oxide (MnSrO3... Specific Chemical Substances § 721.10008 Manganese strontium oxide (MnSrO3). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as manganese strontium...

  19. 40 CFR 721.10008 - Manganese strontium oxide (MnSrO3).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Manganese strontium oxide (MnSrO3... Specific Chemical Substances § 721.10008 Manganese strontium oxide (MnSrO3). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as manganese strontium...

  20. 40 CFR 721.10008 - Manganese strontium oxide (MnSrO3).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Manganese strontium oxide (MnSrO3... Specific Chemical Substances § 721.10008 Manganese strontium oxide (MnSrO3). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as manganese strontium...

  1. The effect of high dose oral manganese exposure on copper, iron and zinc levels in rats.

    PubMed

    Mercadante, Courtney J; Herrera, Carolina; Pettiglio, Michael A; Foster, Melanie L; Johnson, Laura C; Dorman, David C; Bartnikas, Thomas B

    2016-06-01

    Manganese is an essential dietary nutrient and trace element with important roles in mammalian development, metabolism, and antioxidant defense. In healthy individuals, gastrointestinal absorption and hepatobiliary excretion are tightly regulated to maintain systemic manganese concentrations at physiologic levels. Interactions of manganese with other essential metals following high dose ingestion are incompletely understood. We previously reported that gavage manganese exposure in rats resulted in higher tissue manganese concentrations when compared with equivalent dietary or drinking water manganese exposures. In this study, we performed follow-up evaluations to determine whether oral manganese exposure perturbs iron, copper, or zinc tissue concentrations. Rats were exposed to a control diet with 10 ppm manganese or dietary, drinking water, or gavage exposure to approximately 11.1 mg manganese/kg body weight/day for 7 or 61 exposure days. While manganese exposure affected levels of all metals, particularly in the frontal cortex and liver, copper levels were most prominently affected. This result suggests an under-appreciated effect of manganese exposure on copper homeostasis which may contribute to our understanding of the pathophysiology of manganese toxicity. PMID:26988220

  2. 40 CFR 721.10010 - Barium manganese oxide (BaMnO3).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Barium manganese oxide (BaMnO3). 721... Substances § 721.10010 Barium manganese oxide (BaMnO3). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as barium manganese oxide (BaMnO3) (PMN...

  3. 40 CFR 721.10010 - Barium manganese oxide (BaMnO3).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Barium manganese oxide (BaMnO3). 721... Substances § 721.10010 Barium manganese oxide (BaMnO3). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as barium manganese oxide (BaMnO3) (PMN...

  4. 40 CFR 721.10010 - Barium manganese oxide (BaMnO3).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Barium manganese oxide (BaMnO3). 721... Substances § 721.10010 Barium manganese oxide (BaMnO3). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as barium manganese oxide (BaMnO3) (PMN...

  5. 40 CFR 721.10010 - Barium manganese oxide (BaMnO3).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Barium manganese oxide (BaMnO3). 721... Substances § 721.10010 Barium manganese oxide (BaMnO3). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as barium manganese oxide (BaMnO3) (PMN...

  6. 40 CFR 721.10010 - Barium manganese oxide (BaMnO3).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Barium manganese oxide (BaMnO3). 721... Substances § 721.10010 Barium manganese oxide (BaMnO3). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as barium manganese oxide (BaMnO3) (PMN...

  7. Role of liver lysosomes in uptake and biliary excretion of manganese in mice

    SciTech Connect

    Suzuki, H.; Wada, O.

    1981-12-01

    To determine the mechanism of manganese excretion from the liver into bile, manganese content in blood, bile, whole liver, and subcellular fractions of liver was measured following intraperitoneal injection of a single dose of manganese (49 mg Mn(OAc)/sub 2/. 4H/sub 2/O/kg body wt) in mice. Manganese in blood was rapidly incorporated into liver and appeared in bile within hours. Most of the absorbed manganese in liver was recovered in the mitochondrial-lysosomal fraction. Purified nuclei contained only one-tenth of the manganese found in the crude nuclear fraction. Sucrose density gradient centrifugation revealed that lysosomes took up and released manganese more rapidly than mitochondria. Also, manganese content in the liver and bile decreased following pretreatment with trypan blue. These values returned to normal with simultaneous administration of cortisone. Manganese released in vitro from the mitochondrial-lysosomal fraction and manganese in bile were measured as manganese acetate by gel filtration. The results suggest that liver lysosomes play an important role in intrahepatic movement and affect biliary excretion of absorbed manganese.

  8. 66 FR 15399 - Electrolytic Manganese Dioxide From Greece: Final Results of Antidumping Duty Administrative Review

    Federal Register 2010, 2011, 2012, 2013, 2014

    2001-03-19

    ...: Electrolytic Manganese Dioxide from Greece, 66 FR 1950 (January 10, 2001) (Preliminary Results). Scope of... International Trade Administration Electrolytic Manganese Dioxide From Greece: Final Results of Antidumping Duty... antidumping duty order on electrolytic manganese dioxide from Greece. The review covers one...

  9. 65 FR 68978 - Electrolytic Manganese Dioxide From Greece: Final Results of Antidumping Duty Administrative Review

    Federal Register 2010, 2011, 2012, 2013, 2014

    2000-11-15

    ... Administrative Review: Electrolytic Manganese Dioxide from Greece, 65 FR 26570 (May 8, 2000) (Preliminary Results... INTERNATIONAL TRADE ADMINISTRATION (A-484-801) Electrolytic Manganese Dioxide From Greece: Final Results of... the antidumping duty order on electrolytic manganese dioxide from Greece. The review covers...

  10. 40 CFR 721.10013 - Manganese yttrium oxide (Mn2YO5).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Manganese yttrium oxide (Mn2YO5). 721... Substances § 721.10013 Manganese yttrium oxide (Mn2YO5). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as manganese yttrium oxide (Mn2YO5) (PMN...

  11. 40 CFR 721.10009 - Manganese yttrium oxide (MnYO3).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Manganese yttrium oxide (MnYO3). 721... Substances § 721.10009 Manganese yttrium oxide (MnYO3). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as manganese yttrium oxide (MnYO3) (PMN...

  12. 40 CFR 721.10013 - Manganese yttrium oxide (Mn2YO5).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Manganese yttrium oxide (Mn2YO5). 721... Substances § 721.10013 Manganese yttrium oxide (Mn2YO5). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as manganese yttrium oxide (Mn2YO5) (PMN...

  13. 40 CFR 721.10013 - Manganese yttrium oxide (Mn2YO5).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Manganese yttrium oxide (Mn2YO5). 721... Substances § 721.10013 Manganese yttrium oxide (Mn2YO5). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as manganese yttrium oxide (Mn2YO5) (PMN...

  14. 40 CFR 721.10009 - Manganese yttrium oxide (MnYO3).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Manganese yttrium oxide (MnYO3). 721... Substances § 721.10009 Manganese yttrium oxide (MnYO3). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as manganese yttrium oxide (MnYO3) (PMN...

  15. 40 CFR 721.10009 - Manganese yttrium oxide (MnYO3).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Manganese yttrium oxide (MnYO3). 721... Substances § 721.10009 Manganese yttrium oxide (MnYO3). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as manganese yttrium oxide (MnYO3) (PMN...

  16. 40 CFR 721.10013 - Manganese yttrium oxide (Mn2YO5).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Manganese yttrium oxide (Mn2YO5). 721... Substances § 721.10013 Manganese yttrium oxide (Mn2YO5). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as manganese yttrium oxide (Mn2YO5) (PMN...

  17. 40 CFR 721.10009 - Manganese yttrium oxide (MnYO3).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Manganese yttrium oxide (MnYO3). 721... Substances § 721.10009 Manganese yttrium oxide (MnYO3). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as manganese yttrium oxide (MnYO3) (PMN...

  18. Possible roles of manganese redox chemistry in the sulfur cycle

    NASA Technical Reports Server (NTRS)

    Nealson, K. H.

    1985-01-01

    Sulfate reducing bacteria (SRB) are very potent MnO2 reducers by virtue of their sulfide production: H2S reacts rapidly with MnO2 to yield Mn(2), elemental sulfur, and water. In manganese rich zones, Mn cycles rapidly if sulfate is present to drive the reduction and the MnO2 precipitates and sinks into anaerobic zones. The production of sulfide (by organisms requiring organic carbon compounds) to reduce manganese oxides might act to couple the carbon and sulfur cycles in water bodies in which the two cycles are physically separated. Iron has been proposed for this provision of reducing power by (Jorgensen, 1983), but since MnS is soluble and FeS is very insoluble in water, it is equally likely that manganese rather than iron provides the electrons to the more oxidized surface layers.

  19. Recovery of Manganese Ferrite in Nanoform from the Metallurgical Slags

    NASA Astrophysics Data System (ADS)

    Semykina, Anna; Seetharaman, Seshadri

    2011-02-01

    The present work investigates the formation of manganese ferrite of nanosize by oxidation of MnO- and FeO-containing slag. A horizontal resistance furnace was used as an experimental setup. The experiment was conducted in the temperature range of 1573 K to 1673 K (1300 °C to 1400 °C) in an oxidizing atmosphere. The samples were quenched to the cold end of the furnace and were analyzed by X-ray diffraction (XRD). The XRD patterns of the products showed the presence of two phases—manganese ferrite and calcium silicate. The particle size of the manganese ferrite was estimated by the Scherrer formula to be in the range of nanometers.

  20. High manganese concentrations in rocks at Gale crater, Mars

    USGS Publications Warehouse

    Lanza, Nina L.; Fischer, Woodward W.; Wiens, Roger C.; Grotzinger, John; Ollila, Ann M.; Anderson, Ryan B.; Clark, Benton C.; Gellert, Ralf; Mangold, Nicolas; Maurice, Sylvestre; Le Mouélic, Stéphane; Nachon, Marion; Schmidt, Mariek E.; Berger, Jeffrey; Clegg, Samuel M.; Forni, Olivier; Hardgrove, Craig; Melikechi, Noureddine; Newsom, Horton E.; Sautter, Violaine

    2014-01-01

    The surface of Mars has long been considered a relatively oxidizing environment, an idea supported by the abundance of ferric iron phases observed there. However, compared to iron, manganese is sensitive only to high redox potential oxidants, and when concentrated in rocks, it provides a more specific redox indicator of aqueous environments. Observations from the ChemCam instrument on the Curiosity rover indicate abundances of manganese in and on some rock targets that are 1–2 orders of magnitude higher than previously observed on Mars, suggesting the presence of an as-yet unidentified manganese-rich phase. These results show that the Martian surface has at some point in time hosted much more highly oxidizing conditions than has previously been recognized.

  1. Corrosion of stainless steel piping in high manganese fresh water

    SciTech Connect

    Avery, R.E.; Lutey, R.W.; Musick, J.; Pinnow, K.E.; Tuthill, A.H.

    1996-09-01

    A potable water treatment plant, designed to reduce manganese and iron in well water, experienced leaks in the 16 in. (406 mm) raw water headers about nine months after startup. The material, type 304 (UNS 30403) stainless steel, was purchased to American Society of Testing Materials specification A 778, with additional stipulations governing internal finish, the use of filler metal, and pickling for scale removal. Laboratory screenings of deposits for bacteria revealed some potentially additive corrosive effects from microbial action. However, the correlation of corrosion with the presence or absence of heat tint in the heat-affected zone of the circumferential welds prevailed as a primary cause of the corrosion observed beneath an adherent manganese-iron deposit in a low chloride, high manganese, raw water.

  2. The sensitized luminescence of manganese-activated calcite

    USGS Publications Warehouse

    Schulman, J.H.; Evans, L.W.; Ginther, R.J.; Murata, K.J.

    1947-01-01

    Synthetic manganese-activated calcites are shown to be practically inert to ultraviolet excitation in the range 2000-3500A, while they are luminescent under cathode-ray excitation. The incorporation of small amounts of an auxiliary impurity along with the manganese produces the strong response to ultraviolet radiation hitherto ascribed to CaCO3:Mn itself. Three such impurities have been studied: lead, thallium, and cerium. The first two induce excitation in the neighborhood of the mercury resonance line, while the cerium introduces a response principally to longer wave ultraviolet. The strong response to 2537A excitation shown by some natural calcites is likewise found to be due to the presence of lead along with the manganese, rather than to the manganese alone. The data do not warrant ascribing the longer wave-length ultraviolet-excited luminescence of all natural calcites to the action of an auxiliary impurity. The essential identity of the cathode-ray excited luminescence spectra of CaCO 3:Mn, CaCO3: (Pb+Mn), CaCO3:(Tl+Mn), and CaCO3:(Ce+Mn) with the 2537A-excited spectra of the latter three is evidence that the luminescent center in all cases is the manganese ion or the MnO6 group. It is shown that a "cascade" mechanism for the action of the auxiliary impurities, lead, thallium, and cerium, is incorrect; and that the phenomenon must be considered as a case of sensitized luminescence. Owing to the nature of cathode-ray excitation, the manganese activator can be excited by this agent even in the absence of a second impurity. For optical excitation, however, an absorption band for the ultraviolet must be established by building into the CaCO3:Mn a second impurity or "sensitizer.".

  3. Manganese oxidation state mediates toxicity in PC12 cells

    SciTech Connect

    Reaney, S.H. . E-mail: stevereaney@hotmail.com; Smith, D.R.

    2005-06-15

    The role of the manganese (Mn) oxidation state on cellular Mn uptake and toxicity is not well understood. Therefore, undifferentiated PC12 cells were exposed to 0-200 {mu}M Mn(II)-chloride or Mn(III)-pyrophosphate for 24 h, after which cellular manganese levels were measured along with measures of cell viability, function, and cytotoxicity (trypan blue exclusion, medium lactate dehydrogenase (LDH), 8-isoprostanes, cellular ATP, dopamine, serotonin, H-ferritin, transferrin receptor (TfR), Mn-superoxide dismutase (MnSOD), and copper-zinc superoxide dismutase (CuZnSOD) protein levels). Exposures to Mn(III) >10 {mu}M produced 2- to 5-fold higher cellular manganese levels than equimolar exposures to Mn(II). Cell viability and ATP levels both decreased at the highest Mn(II) and Mn(III) exposures (150-200 {mu}M), while Mn(III) exposures produced increases in LDH activity at lower exposures ({>=}50 {mu}M) than did Mn(II) (200 {mu}M only). Mn(II) reduced cellular dopamine levels more than Mn(III), especially at the highest exposures (50% reduced at 200 {mu}M Mn(II)). In contrast, Mn(III) produced a >70% reduction in cellular serotonin at all exposures compared to Mn(II). Different cellular responses to Mn(II) exposures compared to Mn(III) were also observed for H-ferritin, TfR, and MnSOD protein levels. Notably, these differential effects of Mn(II) versus Mn(III) exposures on cellular toxicity could not simply be accounted for by the different cellular levels of manganese. These results suggest that the oxidation state of manganese exposures plays an important role in mediating manganese cytotoxicity.

  4. Battery manganese dioxide - a survey of its history and etymology

    NASA Astrophysics Data System (ADS)

    Euler, Karl-Jaochim

    1982-10-01

    Manganese dioxide was known two thousand years ago. It was described by Plinius. Later, Basilius Valentinus named it "Braunstein", the brownstone. Its chemical nature was recognized by Scheele and his student Gahn. Its first application in the field of batteries seems to have been by Ritter. Following Leclanchéś invention it has been used on a large scale in dry batteries. In 1977 about 300 000 metric tons of battery grade manganese dioxide were consumed. More than 50% of the oxide is derived from natural ores, and about one third is obtained as electrochemically deposited dioxide.

  5. Transuranic interfacial reaction studies on manganese oxidemineral surfaces

    SciTech Connect

    Shaughnessy, Dawn A.; Nitsche, Heino; Serne, R. Jeffrey; Shuh,David K.; Waychunas, Glenn A.; Booth, Corwin H.; Cantrell, Kirk J.

    2002-05-15

    Several DOE sites have been contaminated by transuranicradionuclide (TRU) discharges including neptunium and plutonium. Theirinteraction with the surrounding geological media can affect thetransport and remediation of these radionuclides in the environment.Manganese based minerals, present as minor phases in the vadose zone, canpreferentially sequester TRU over other minerals present in largerquantities. The objective of this project is to understand theinteractions between plutonium and neptunium and manganese oxyhydroxideminerals to predict potential hazards they represent to the environment,as well as to provide important scientific information for the design ofeffective remediation strategies for contaminated DOE sites.

  6. Manganese-Based Magnets: Manganese-Based Permanent Magnet with 40 MGOe at 200°C

    SciTech Connect

    2012-01-01

    REACT Project: PNNL is working to reduce the cost of wind turbines and EVs by developing a manganese-based nano-composite magnet that could serve as an inexpensive alternative to rare-earth-based magnets. The manganese composite, made from low-cost and abundant materials, could exceed the performance of today’s most powerful commercial magnets at temperature higher than 200°C. Members of PNNL’s research team will leverage comprehensive computer high-performance supercomputer modeling and materials testing to meet this objective. Manganese-based magnets could withstand higher temperatures than their rare earth predecessors and potentially reduce the need for any expensive, bulky engine cooling systems for the motor and generator. This would further contribute to cost savings for both EVs and wind turbines.

  7. Impact of dietary manganese concentration on status criteria to determine manganese requirement in piglets.

    PubMed

    Pallauf, J; Kauer, C; Most, E; Habicht, S D; Moch, J

    2012-12-01

    The Mn requirement for pigs is not well established. This study aimed to find criteria for assessing growing piglet supply status for Mn and to determine whether the current Mn recommendations meet the requirements for piglets. Thirty-six weaned male castrated 27-day-old piglets (7.24 ± 0.69 kg) were randomized into six groups of six piglets each and housed individually in stainless steel metabolic cages for 42 days. The piglets were fed a diet based on skimmed milk powder and corn starch with increasing Mn concentrations (0.24; 2; 4; 8; 16; or 32 mg Mn/kg diet as-fed). In week 6, Mn0.24 led to reduced feed intake (p < 0.05). Manganese concentrations in blood, liver, kidney, lung, heart, phalanx proximalis, pancreas and skeletal muscle were influenced by the dietary Mn supply (p < 0.05). The activity of the Mn-containing superoxide dismutase in the heart as well as relative arginase activity in the liver were lower in groups Mn0.24, Mn2 and Mn4 compared with the higher supplemented groups (p < 0.05). The relative arginase activity increased clearly with enhanced dietary Mn up to 16 mg/kg and correlated with Mn concentration in the liver. Manganese concentrations in the liver, kidney and phalanx proximalis seem to be suitable biomarkers for Mn status. A 4 mg/kg dietary Mn concentration recommended by NRC (1998, Nutrient Requirements of Swine. National Academy Press, Washington DC.) did not fulfil piglet requirements. Under the conditions investigated, 16 mg Mn/kg diet were necessary to reach a plateau in specific enzyme activity and Mn concentration in organs. PMID:21883497

  8. Manganese deficiency and toxicity: are high or low dietary amounts of manganese cause for concern?

    PubMed

    Finley, J W; Davis, C D

    1999-01-01

    Manganese is an essential trace element that is required for the activity of several enzymes. Manganese is also quite toxic when ingested in large amounts, such as the inhalation of Mn-laden dust by miners. This review examines Mn intake by way of the food supply and poses the question: Is there reason to be concerned with Mn toxicity or deficiency in free-living populations in North America? Although much remains to be learned of the functions of Mn, at present there are only a few vaguely described cases of Mn deficiency in the medical literature. Given the heterogeneity of the North American food supply, it is difficult to see the possibility of more than greatly isolated and unique instances of Mn deficiency. However, low Mn-dependent superoxide dismutase activity may be associated with cancer susceptibility, and deserves further study. There may be reasons, however, to be concerned about Mn toxicity under some very specialized conditions. Increasing numbers of young people are adopting a vegetarian lifestyle which may greatly increase Mn intake. Iron deficiency may increase Mn absorption and further increase the body-burden of Mn, especially in vegetarians. Mn is eliminated primarily through the bile, and hepatic dysfunction could depress Mn excretion and further contribute to the body burden. Would such a combination of events predispose substantial numbers of people to chronic Mn toxicity? At present, there is no definite proof of this occurring, but given the state of knowledge at the present time, more studies with longer time-frames and more sensitive methods of analysis are needed. PMID:10475586

  9. Microbeam methodologies as powerful tools in manganese hyperaccumulation research: present status and future directions.

    PubMed

    Fernando, Denise R; Marshall, Alan; Baker, Alan J M; Mizuno, Takafumi

    2013-01-01

    Microbeam studies over the past decade have garnered unique insight into manganese (Mn) homeostasis in plant species that hyperaccumulate this essential mineral micronutrient. Electron- and/or proton-probe methodologies employed to examine tissue elemental distributions have proven highly effective in illuminating excess foliar Mn disposal strategies, some apparently unique to Mn hyperaccumulating plants. When applied to samples prepared with minimal artefacts, these are powerful tools for extracting true 'snapshot' data of living systems. For a range of reasons, Mn hyperaccumulation is particularly suited to in vivo interrogation by this approach. Whilst microbeam investigation of metallophytes is well documented, certain methods originally intended for non-biological samples are now widely applied in biology. This review examines current knowledge about Mn hyperaccumulators with reference to microbeam methodologies, and discusses implications for future research into metal transporters. PMID:23970891

  10. Microbeam methodologies as powerful tools in manganese hyperaccumulation research: present status and future directions

    PubMed Central

    Fernando, Denise R.; Marshall, Alan; Baker, Alan J. M.; Mizuno, Takafumi

    2013-01-01

    Microbeam studies over the past decade have garnered unique insight into manganese (Mn) homeostasis in plant species that hyperaccumulate this essential mineral micronutrient. Electron- and/or proton-probe methodologies employed to examine tissue elemental distributions have proven highly effective in illuminating excess foliar Mn disposal strategies, some apparently unique to Mn hyperaccumulating plants. When applied to samples prepared with minimal artefacts, these are powerful tools for extracting true ‘snapshot’ data of living systems. For a range of reasons, Mn hyperaccumulation is particularly suited to in vivo interrogation by this approach. Whilst microbeam investigation of metallophytes is well documented, certain methods originally intended for non-biological samples are now widely applied in biology. This review examines current knowledge about Mn hyperaccumulators with reference to microbeam methodologies, and discusses implications for future research into metal transporters. PMID:23970891

  11. Manganese-Induced Parkinsonism and Parkinson’s Disease: Shared and Distinguishable Features

    PubMed Central

    Kwakye, Gunnar F.; Paoliello, Monica M.B.; Mukhopadhyay, Somshuvra; Bowman, Aaron B.; Aschner, Michael

    2015-01-01

    Manganese (Mn) is an essential trace element necessary for physiological processes that support development, growth and neuronal function. Secondary to elevated exposure or decreased excretion, Mn accumulates in the basal ganglia region of the brain and may cause a parkinsonian-like syndrome, referred to as manganism. The present review discusses the advances made in understanding the essentiality and neurotoxicity of Mn. We review occupational Mn-induced parkinsonism and the dynamic modes of Mn transport in biological systems, as well as the detection and pharmacokinetic modeling of Mn trafficking. In addition, we review some of the shared similarities, pathologic and clinical distinctions between Mn-induced parkinsonism and Parkinson’s disease. Where possible, we review the influence of Mn toxicity on dopamine, gamma aminobutyric acid (GABA), and glutamate neurotransmitter levels and function. We conclude with a survey of the preventive and treatment strategies for manganism and idiopathic Parkinson’s disease (PD). PMID:26154659

  12. Manganese-Induced Parkinsonism and Parkinson's Disease: Shared and Distinguishable Features.

    PubMed

    Kwakye, Gunnar F; Paoliello, Monica M B; Mukhopadhyay, Somshuvra; Bowman, Aaron B; Aschner, Michael

    2015-07-01

    Manganese (Mn) is an essential trace element necessary for physiological processes that support development, growth and neuronal function. Secondary to elevated exposure or decreased excretion, Mn accumulates in the basal ganglia region of the brain and may cause a parkinsonian-like syndrome, referred to as manganism. The present review discusses the advances made in understanding the essentiality and neurotoxicity of Mn. We review occupational Mn-induced parkinsonism and the dynamic modes of Mn transport in biological systems, as well as the detection and pharmacokinetic modeling of Mn trafficking. In addition, we review some of the shared similarities, pathologic and clinical distinctions between Mn-induced parkinsonism and Parkinson's disease. Where possible, we review the influence of Mn toxicity on dopamine, gamma aminobutyric acid (GABA), and glutamate neurotransmitter levels and function. We conclude with a survey of the preventive and treatment strategies for manganism and idiopathic Parkinson's disease (PD). PMID:26154659

  13. Improved performance of carbon nanotubes—manganese doped cadmium sulfide quantum dot nanocomposite based solar cell

    NASA Astrophysics Data System (ADS)

    Kaur, Rajnish; Priya, Nidhi; Deep, Akash

    2016-01-01

    The nanocomposites of carbon nanotubes with quantum dots (MWCNT-QDS) display the capability of light induced charge dissociation and transport, which make them suitable for photovoltaic applications. The present work reports the coupling of multiwalled CNT (MWCNT) with L-cysteine (2-amino 3-mercaptopropionic acid) capped manganese doped cadmium sulfide QDs (CdS:Mn). The confirmation of the MWCNT-CdS:Mn nanocomposite formation is done with various instrumental techniques. Current-voltage studies of the MWCNT-CdS:Mn thin film indicate their semiconducting behavior. Further, cyclic voltammetry and frequency response analyses of the above MWCNT-CdS:Mn thin film have highlighted their potential application as a photoanode material in dye sanitized solar cells. It has been demonstrated that the use of MWCNT-CdS:Mn nanocomposite as a photoanode material offer better photocurrent characteristics as compared to QDS alone.

  14. Pathophysiology of Manganese-Associated Neurotoxicity

    PubMed Central

    Racette, Brad A.; Aschner, Michael; Guilarte, Tomas R.; Dydak, Ulrike; Criswell, Susan R.; Zheng, Wei

    2012-01-01

    Conference Summary Manganese (Mn) is a well established neurotoxin associated with specific damage to the basal ganglia in humans. The phenotype associated with Mn neurotoxicity was first described in two workers with occupational exposure to Mn oxide.(Couper, 1837) Although the description did not use modern clinical terminology, a parkinsonian illness characterized by slowness of movement (bradykinesia), masked facies, and gait impairment (postural instability) appears to have predominated. Nearly 100 years later an outbreak of an atypical parkinsonian illness in a Chilean Mn mine provided a phenotypic description of a fulminant neurologic disorder with parkinsonism, dystonia, and neuropsychiatric symptoms.(Rodier J, 1955) Exposures associated with this syndrome were massive and an order of magnitude greater than modern exposures.(Rodier J, 1955; Hobson et al., 2011) The clinical syndrome associated with Mn neurotoxicity has been called manganism. Modern exposures to Mn occur primarily through occupations in the steel industry and welding. These exposures are often chronic and varied, occurring over decades in the healthy workforce. Although the severe neurologic disorder described by Rodier and Couper are no longer seen, several reports have suggested a possible increased risk of neurotoxicity in these workers.(Racette et al., 2005b; Bowler et al., 2007; Harris et al., 2011) Based upon limited prior imaging and pathologic investigations into the pathophysiology of neurotoxicity in Mn exposed workers,(Huang et al., 2003) many investigators have concluded that the syndrome spares the dopamine system distinguishing manganism from Parkinson disease (PD), the most common cause of parkinsonism in the general population, and a disease with characteristic degenerative changes in the dopaminergic system.(Jankovic, 2005) The purpose of this symposium was to highlight recent advances in the understanding of the pathophysiology of Mn associated neurotoxicity from C. elegans

  15. Time to Re-evaluate the Guideline Value for Manganese in Drinking Water?

    PubMed Central

    Ljung, Karin; Vahter, Marie

    2007-01-01

    Objective We reviewed the scientific background for the current health-based World Health Organization (WHO) guideline value for manganese in drinking water. Data sources and extraction The initial starting point was the background document for the development of the WHO’s guideline value for manganese in drinking water as well as other regulations and recommendations on manganese intake levels. Data referred to in these documents were traced back to the original research papers. In addition, we searched for scientific reports on manganese exposure and health effects. Data synthesis The current health-based guideline value for manganese in drinking water is based partly on debatable assumptions, where information from previous reports has been used without revisiting original scientific articles. Presently, preparation of common infant formulas with water containing manganese concentrations equivalent to the WHO guideline value will result in exceeding the maximum manganese concentration for infant formula. However, there are uncertainties about how this maximum value was derived. Concurrently, there is increasing evidence of negative neurologic effects in children from excessive manganese exposure. Conclusions The increasing number of studies reporting associations between neurologic symptoms and manganese exposure in infants and children, in combination with the questionable scientific background data used in setting the manganese guideline value for drinking water, certainly warrant a re-evaluation of the guideline value. Further research is needed to understand the causal relationship between manganese exposure and children’s health, and to enable an improved risk assessment. PMID:18007980

  16. THE STATE OF MANGANESE IN THE PHOTOSYNTHETIC APPARATUS. I. EXAFS STUDIES ON CHLOROPLASTS AND di-u-oxo BRIDGED di-MANGANESE MODEL COMPOUNDS

    SciTech Connect

    Kirby, J. A.; Robertson, A. S.; Smith, J. P.; Thompson, A. C.; Thompson, A. C.; Klein, M. P.

    1980-11-01

    Extended X-ray Absorption Fine Structure (EXAFS) studies on the manganese contained in spinach chloroplasts and on certain di-u-oxo bridged manganese dimers of the form (X{sub 2}Mn)O{sub 2}(MnX{sub 2} (X=2,2'-bypyridine and 1,10-phenanthroline) are reported. From these studies, the manganese associated with photosynthetic oxygen evolution is suggested to occur as a bridged transition metal dimer with most likely another manganese. Extensive details on the analysis are included.

  17. Reductive leaching of low-grade manganese ore with pre-processed cornstalk

    NASA Astrophysics Data System (ADS)

    Yi, Ai-fei; Wu, Meng-ni; Liu, Peng-wei; Feng, Ya-li; Li, Hao-ran

    2015-12-01

    Cornstalk is usually directly used as a reductant in reductive leaching manganese. However, low utilization of cornstalk makes low manganese dissolution ratio. In the research, pretreatment for cornstalk was proposed to improve manganese dissolution ratio. Cornstalk was preprocessed by a heated sulfuric acid solution (1.2 M of sulfuric acid concentration) for 10 min at 80°C. Thereafter, both the pretreated solution and the residue were used as a reductant for manganese leaching. This method not only exhibited superior activity for hydrolyzing cornstalk but also enhanced manganese dissolution. These effects were attributed to an increase in the amount of reductive sugars resulting from lignin hydrolysis. Through acid pretreatment for cornstalk, the manganese dissolution ratio was improved from 50.14% to 83.46%. The present work demonstrates for the first time the effective acid pretreatment of cornstalk to provide a cost-effective reductant for manganese leaching.

  18. Mn-Ti-Zr (Manganese-Titanium-Zirconium)

    NASA Astrophysics Data System (ADS)

    Materials Science International Team MSIT

    This document is part of Subvolume C3 'Non-Ferrous Metal Systems. Part 3: Selected Soldering and Brazing Systems' of Volume 11 'Ternary Alloy Systems - Phase Diagrams, Crystallographic and Thermodynamic Data critically evaluated by MSIT®' of Landolt-Börnstein - Group IV 'Physical Chemistry'. It provides data of the ternary system Manganese-Titanium-Zirconium.

  19. EFFECTS OF MANGANESE AND THEIR MODIFICATION BY HEXAMETAPHOSPHATE

    EPA Science Inventory

    The ability of oral Mn(+2) to produce the depletions of dopamine in the corpus striata characteristic of the Parkinson-like syndrome in manganese workers was examined in rats. A second objective of this work was to study the biological interactions between Mn(+2) and sodium hexam...

  20. Estimating Air-Manganese Exposures in Two Ohio Towns

    EPA Science Inventory

    Manganese (Mn), a nutrient required for normal metabolic function, is also a persistent air pollutant and a known neurotoxin at high concentrations. Elevated exposures can result in a number of motor and cognitive deficits. Quantifying chronic personal exposures in residential po...

  1. Exposure to Environmental Air Manganese and Medication Use

    EPA Science Inventory

    Manganese (Mn) is an essential element with natural low levels found in water, food, and air, but due to industrialized processes, both workplace and the environmental exposures to Mn have increased. Recently, environmental studies have reported physical and mental health problem...

  2. Cu-Mn-Si (Copper-Manganese-Silicon)

    NASA Astrophysics Data System (ADS)

    Materials Science International Team MSIT

    This document is part of Subvolume C2 'Non-Ferrous Metal Systems. Part 2: Selected Copper Systems' of Volume 11 'Ternary Alloy Systems - Phase Diagrams, Crystallographic and Thermodynamic Data critically evaluated by MSIT®' of Landolt-Börnstein - Group IV 'Physical Chemistry'. It provides data of the ternary system Copper-Manganese-Silicon.

  3. MANGANESE DIOXIDE COATED FILTERS FOR REMOVING RADIUM FROM DRINKING WATER

    EPA Science Inventory

    Research was performed using manganese dioxide (MnO2) to demonstrate that above pH3 cations are adsorbed from solution in the order of their affinity, and that the interaction is characterized by the pH dependence of the metal. The relationship of the zero point charge of pH and ...

  4. How pharmacokinetic modeling could improve a risk assessment for manganese

    EPA Science Inventory

    The neurotoxicity of manganese (Mn) is well established, yet the risk assessment of Mn is made complex by certain enigmas. These include apparently greatertoxicity via inhalation compared to oral exposure and greater toxicity in humans compared to rats. In addition, until recentl...

  5. Community Exposure to Air Manganese and Motor and Cognitive Outcomes

    EPA Science Inventory

    Although manganese (Mn) is an essential nutrient, occupational studies have shown inhaling high levels of Mn can lead to adverse nervous system health effects. Few studies have examined the health effects of air-Mn exposure on adults in a community. We conducted a cross-sectional...

  6. ChemCam Update ? Manganese Oxides on Mars

    ScienceCinema

    Lanza, Nina

    2016-07-14

    A recent discovery of manganese oxides in Martian rocks might tell us that the Red Planet was once more Earth-like than previously believed. So what exactly does that mean? Nina Lanza, Los Alamos scientist and lead author of the new paper about these findings in Geophysical Research Letters, breaks it down for us.

  7. Elements of the iron and manganese cycles in Lake Baikal

    USGS Publications Warehouse

    Granina, L.Z.; Callender, E.

    2007-01-01

    Using data obtained in recent years, we considered the external mass balance and characteristics of internal iron and manganese cycles in Lake Baikal (biological uptake, remineralization, sedimentary and diffusive fluxes, accumulation in sediments, time of renewal, etc.). Some previous results and common concepts were critically reevaluated. ?? Pleiades Publishing, Ltd. 2007.

  8. INHALATION TOXICOLOGY OF AIRBORNE PARTICULATE MANGANESE IN RHESUS MONKEYS

    EPA Science Inventory

    Four male and four female rhesus monkeys were exposed to manganese oxide (Mn3O4) aerosol at 100 micrograms/cubic meter in an exposure chamber for periods up to 66 weeks. Three male and three female monkeys were maintained as unexposed controls. Observation and clinical chemistry ...

  9. Cognitive Function Related to Environmental Exposure to Manganese

    EPA Science Inventory

    Background: The towns of Marietta and East Liverpool (EL), Ohio, have been identified as having elevated manganese (Mn) in air due to industrial pollution. Objectives: To evaluate relationships between environmental Mn (Mn-air) exposure and distance from the source and cognitive...

  10. 63 FR 30254 - Electrolytic Manganese Dioxide From Greece and Japan

    Federal Register 2010, 2011, 2012, 2013, 2014

    1998-06-03

    .../89 54 FR 16010 A-484-801 04/17/89 54 FR 15243 Japan 731-TA-408 4/10/89 54 FR 16010 A-588-806 04/17/89 54 FR 15244 SUMMARY: The Commission invites comments from the public on whether changed circumstances... COMMISSION Electrolytic Manganese Dioxide From Greece and Japan AGENCY: United States International...

  11. 64 FR 54353 - Electrolytic Manganese Dioxide From Greece and Japan

    Federal Register 2010, 2011, 2012, 2013, 2014

    1999-10-06

    ... published at 63 FR 30599, June 5, 1998, and may be downloaded from the Commission's World Wide Web site at... reviews pursuant to section 751(c)(5) of the Act should proceed (64 FR 46407, August 25, 1999). A record... COMMISSION Electrolytic Manganese Dioxide From Greece and Japan AGENCY: United States International...

  12. 64 FR 46407 - Electrolytic Manganese Dioxide from Greece and Japan

    Federal Register 2010, 2011, 2012, 2013, 2014

    1999-08-25

    ..., including the text of subpart F of part 207, are published at 63 FR 30599, June 5, 1998, and may be... interested party group response to its notice of institution (64 FR 23675, Mar. 3, 1999) was adequate with... COMMISSION Electrolytic Manganese Dioxide from Greece and Japan AGENCY: United States International...

  13. Iron mitigates DMT1-mediated manganese cytotoxicity via the ASK1-JNK signaling axis: Implications of iron supplementation for manganese toxicity.

    PubMed

    Tai, Yee Kit; Chew, Katherine C M; Tan, Bryce W Q; Lim, Kah-Leong; Soong, Tuck Wah

    2016-01-01

    Manganese (Mn(2+)) neurotoxicity from occupational exposure is well documented to result in a Parkinson-like syndrome. Although the understanding of Mn(2+) cytotoxicity is still incomplete, both Mn(2+) and Fe(2+) can be transported via the divalent metal transporter 1 (DMT1), suggesting that competitive uptake might disrupt Fe(2+) homeostasis. Here, we found that DMT1 overexpression significantly enhanced Mn(2+) cytoplasmic accumulation and JNK phosphorylation, leading to a reduction in cell viability. Although a robust activation of autophagy was observed alongside these changes, it did not trigger autophagic cell death, but was instead shown to be essential for the degradation of ferritin, which normally sequesters labile Fe(2+). Inhibition of ferritin degradation through the neutralization of lysosomal pH resulted in increased ferritin and enhanced cytoplasmic Fe(2+) depletion. Similarly, direct Fe(2+) chelation also resulted in aggravated Mn(2+)-mediated JNK phosphorylation, while Fe(2+) repletion protected cells, and this occurs via the ASK1-thioredoxin pathway. Taken together, our study presents the novel findings that Mn(2+) cytotoxicity involves the depletion of the cytoplasmic Fe(2+) pool, and the increase in autophagy-lysosome activity is important to maintain Fe(2+) homeostasis. Thus, Fe(2+) supplementation could have potential applications in the prevention and treatment of Mn(2+)-mediated toxicity. PMID:26878799

  14. Iron mitigates DMT1-mediated manganese cytotoxicity via the ASK1-JNK signaling axis: Implications of iron supplementation for manganese toxicity

    PubMed Central

    Tai, Yee Kit; Chew, Katherine C. M.; Tan, Bryce W. Q.; Lim, Kah-Leong; Soong, Tuck Wah

    2016-01-01

    Manganese (Mn2+) neurotoxicity from occupational exposure is well documented to result in a Parkinson-like syndrome. Although the understanding of Mn2+ cytotoxicity is still incomplete, both Mn2+ and Fe2+ can be transported via the divalent metal transporter 1 (DMT1), suggesting that competitive uptake might disrupt Fe2+ homeostasis. Here, we found that DMT1 overexpression significantly enhanced Mn2+ cytoplasmic accumulation and JNK phosphorylation, leading to a reduction in cell viability. Although a robust activation of autophagy was observed alongside these changes, it did not trigger autophagic cell death, but was instead shown to be essential for the degradation of ferritin, which normally sequesters labile Fe2+. Inhibition of ferritin degradation through the neutralization of lysosomal pH resulted in increased ferritin and enhanced cytoplasmic Fe2+ depletion. Similarly, direct Fe2+ chelation also resulted in aggravated Mn2+-mediated JNK phosphorylation, while Fe2+ repletion protected cells, and this occurs via the ASK1-thioredoxin pathway. Taken together, our study presents the novel findings that Mn2+ cytotoxicity involves the depletion of the cytoplasmic Fe2+ pool, and the increase in autophagy-lysosome activity is important to maintain Fe2+ homeostasis. Thus, Fe2+ supplementation could have potential applications in the prevention and treatment of Mn2+-mediated toxicity. PMID:26878799

  15. Reductive dissolution and reactive solute transport in a sewage-contaminated glacial outwash aquifer

    USGS Publications Warehouse

    Lee, R.W.; Bennett, P.C.

    1998-01-01

    Contamination of shallow ground water by sewage effluent typically contains reduced chemical species that consume dissolved oxygen, developing either a low oxygen geochemical environment or an anaerobic geochemical environment. Based on the load of reduced chemical species discharged to shallow ground water and the amounts of reactants in the aquifer matrix, it should be possible to determine chemical processes in the aquifer and compare observed results to predicted ones. At the Otis Air Base research site (Cape Cod, Massachusetts) where sewage effluent has infiltrated the shallow aquifer since 1936, bacterially mediated processes such as nitrification, denitrification, manganese reduction, and iron reduction have been observed in the contaminant plume. In specific areas of the plume, dissolved manganese and iron have increased significantly where local geochemical conditions are favorable for reduction and transport of these constituents from the aquifer matrix. Dissolved manganese and iron concentrations ranged from 0.02 to 7.3 mg/L, and 0.001 to 13.0 mg/L, respectively, for 21 samples collected from 1988 to 1989. Reduction of manganese and iron is linked to microbial oxidation of sewage carbon, producing bicarbonate and the dissolved metal ions as by-products. Calculated production and flux of CO2 through the unsaturated zone from manganese reduction in the aquifer was 0.035 g/m2/d (12% of measured CO2 flux during winter). Manganese is limited in the aquifer, however. A one-dimensional, reaction-coupled transport model developed for the mildly reducing conditions in the sewage plume nearest the source beds showed that reduction, transport, and removal of manganese from the aquifer sediments should result in iron reduction where manganese has been depleted.

  16. A child with chronic manganese exposure from drinking water.

    PubMed Central

    Woolf, Alan; Wright, Robert; Amarasiriwardena, Chitra; Bellinger, David

    2002-01-01

    The patient's family bought a home in a suburb, but the proximity of the house to wetlands and its distance from the town water main prohibited connecting the house to town water. The family had a well drilled and they drank the well water for 5 years, despite the fact that the water was turbid, had a metallic taste, and left an orange-brown residue on clothes, dishes, and appliances. When the water was tested after 5 years of residential use, the manganese concentration was elevated (1.21 ppm; U.S. Environmental Protection Agency reference, < 0.05 ppm). The family's 10-year-old son had elevated manganese concentrations in whole blood, urine, and hair. The blood manganese level of his brother was normal, but his hair manganese level was elevated. The patient, the 10-year-old, was in the fifth grade and had no history of learning problems; however, teachers had noticed his inattentiveness and lack of focus in the classroom. Our results of cognitive testing were normal, but tests of memory revealed a markedly below-average performance: the patient's general memory index was at the 13th percentile, his verbal memory at the 19th percentile, his visual memory at the 14th percentile, and his learning index at the 19th percentile. The patient's free recall and cued recall tests were all 0.5-1.5 standard deviations (1 SD = 16th percentile) below normal. Psychometric testing scores showed normal IQ but unexpectedly poor verbal and visual memory. These findings are consistent with the known toxic effects of manganese, although a causal relationship cannot necessarily be inferred. PMID:12055054

  17. Hot coal gas desulfurization with manganese-based sorbents

    SciTech Connect

    Hepworth, M.T.; Ben-Slimane, R.

    1995-11-01

    The primary major deposit of manganese in the US which can be readily mined by an in situ process is located in the Emily district of Minnesota. The US Bureau of Mines Research Centers at both the Twin Cities and Salt Lake City have developed a process for extracting and refining manganese in the form of a high-purity carbonate product. This product has been formulated into pellets by a multi-step process of drying, calcination, and induration to produce relatively high-strength formulations which are capable of being used for hot fuel gas desulfurization. These pellets, which have been developed at the University of Minnesota under joint sponsorship of the US Department of Energy and the US Bureau of Mines, appear superior to other, more expensive, formulations of zinc titanate and zinc ferrite which have previously been studied for multi-cycle loading (desulfurization) and regeneration (evolution of high-strength SO{sub 2} and restoration of pellet reactivity). Although these other formulations have been under development for the past twelve years, their prices still exceed $7 per pound. If manganese pellets perform as predicted in fixed bed testing, and if a significant number of utilities which burn high-sulfur coals incorporate combined-cycle gasification with hot coal gas desulfurization as a viable means of increasing conversion efficiencies, then the potential market for manganese pellets may be as high as 200,000 tons per year at a price not less than $3 per pound. This paper discusses the role of manganese pellets in the desulfurization process with respect to the integrated gasification combined-cycle (IGCC) for power generation.

  18. An approach for manganese biomonitoring using a manganese carrier switch in serum from transferrin to citrate at slightly elevated manganese concentration.

    PubMed

    Michalke, B; Aslanoglou, L; Ochsenkühn-Petropoulou, M; Bergström, B; Berthele, A; Vinceti, M; Lucio, M; Lidén, G

    2015-10-01

    After high-dose-short-term exposure (usually from occupational exposure) and even more under low-dose long term exposure (mainly environmental) manganese (Mn) biomonitoring is still problematic since these exposure scenarios are not necessarily reflected by a significant increase of total Mn in blood or serum. Usually, Mn concentrations of exposed and unexposed persons overlap and individual differentiation is often not possible. In this paper Mn speciation on a large sample size (n=180) was used in order to be able to differentiate between highly Mn-exposed or low or unexposed individuals at low total Mn concentration in serum (Mn(S)). The whole sample set consisted of three subsets from Munich, Emilia Romagna region in Italy and from Sweden. It turned out that also at low total Mn(S) concentrations a change in major Mn carriers in serum takes place from Mn-transferrin (Mn-Tf(S)) towards Mn-citrate (Mn-Cit(S)) with high statistical significance (p<0.000002). This carrier switch from Mn-Tf(S) to Mn-Cit(S) was observed between Mn(S) concentrations of 1.5μg/L to ca. 1.7μg/L. Parallel to this carrier change, for sample donors from Munich where serum and cerebrospinal fluid were available, the concentration of Mn beyond neural barriers - analysed as Mn in cerebrospinal fluid (Mn(C)) - positively correlates to Mn-Cit(S) when Mn(S) concentration was above 1.7μg/L. The correlation between Mn-Cit(S) and Mn(C) reflects the facilitated Mn transport through neural barrier by means of Mn-citrate. Regional differences in switch points from Mn-Tf(S) to Mn-Cit(S) were observed for the three sample subsets. It is currently unknown whether these differences are due to differences in location, occupation, health status or other aspects. Based on our results, Mn-Cit(S) determination was considered as a potential means for estimating the Mn load in brain and CSF, i.e., it could be used as a biomarker for Mn beyond neural barrier. For a simpler Mn-Cit(S) determination than size

  19. Manganese chromium isotope systematics of carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Shukolyukov, A.; Lugmair, G. W.

    2006-10-01

    In this article we present the results of Cr isotope investigations of different types of carbonaceous chondrites and of the pallasite Eagle Station. The 53Cr/ 52Cr ratios in the bulk samples of carbonaceous chondrites are correlated with 55Mn/ 52Cr ratios. The slope of the correlation line yields a 53Mn/ 55Mn ratio of (8.5 ± 1.5) × 10 - 6 at the time of Mn/Cr fractionation. Mapping this ratio onto an absolute time scale yields a time for this event of 4568.1 + 0.8/- 1.1 Ma ago. This time is very similar to the formation age of Efremovka CAIs of 4567.2 ± 0.6 Ma [Y. Amelin, A. N. Krot, I. D. Hutcheon, A. A. Ulyanov, Lead isotopic ages of chondrules and calcium-aluminum-rich inclusions, Science 297 (2002) 1678-1683], to a time of the chondrule formation of 4568 ± 1 Ma ago [L.E. Nyquist, D. Lindstrom, D. Mittlefehldt, C.-Y. Shih, H. Wiesmann, S. Wentworth, R. Martinez, Manganese-chromium formation intervals for chondrules from the Bishunpur and Chainpur meteorites, Meteorit. Planet. Sci. 36 (2001) 911-938], which, most likely, constrains early global high-temperature Mn/Cr fractionation in a nebular setting. The bulk samples of carbonaceous chondrites exhibit clear 54Cr excesses ( 54Cr *) that are correlated with the 53Cr excesses ( 53Cr *) and also with Mn/Cr ratios. One possible explanation of this correlation is that 54Cr * is also radiogenic, like 53Cr *, and was formed by the decay of the short-lived parent radionuclide 54Mn. The very short half-life of 54Mn of 312 days would require that both short-lived radionuclides 53Mn and 54Mn were generated locally in spallation reactions during the early period of an active sun. The alternative and possibly more plausible explanation is the heterogeneous addition of presolar material. The presolar component, enriched in 54Cr, is mostly contained in the matrix of carbonaceous chondrites. The relative amount of matrix decreases in the sequence CI > CM > CO,CV. A large proportion of Mn is associated with the matrix while

  20. Manganese(III) binding to a pyoverdine siderophore produced by a manganese(II)-oxidizing bacterium

    NASA Astrophysics Data System (ADS)

    Parker, Dorothy L.; Sposito, Garrison; Tebo, Bradley M.

    2004-12-01

    The possible roles of siderophores (high affinity chelators of iron(III)) in the biogeochemistry of manganese remain unknown. Here we investigate the interaction of Mn(III) with a pyoverdine-type siderophore (PVD MnB1) produced by the model Mn(II)-oxidizing bacterium Pseudomonas putida strain MnB1. PVD MnB1 confirmed typical pyoverdine behavior with respect to: (a) its absorption spectrum at 350-600 nm, both in the absence and presence of Fe(III), (b) the quenching of its fluorescence by Fe(III), (c) the formation of a 1:1 complex with Fe(III), and (d) the thermodynamic stability constant of its Fe(III) complex. The Mn(III) complex of PVD MnB1 had a 1:1 Mn:pvd molar ratio, showed fluorescence quenching, and exhibited a light absorption spectrum (A max = 408-410 nm) different from that of either PVD MnB1-Fe(III) or uncomplexed PVD MnB1. Mn(III) competed strongly with Fe(III) for binding by PVD MnB1 in culture filtrates (pH 8, 4°C). Equilibration with citrate, a metal-binding ligand, did not detectably release Mn from its PVD MnB1 complex at a citrate/PVD MnB1 molar ratio of 830 (pH 8, 4°C), whereas pyrophosphate under the same conditions removed 55% of the Mn from its PVD MnB1 complex. Most of the PVD MnB1-complexed Mn was released by reaction with ascorbate, a reducing agent, or with EDTA, a ligand that is also oxidized by Mn(III). Data on the competition for binding to PVD MnB1 by Fe(III) vs. Mn(III) were used to determine a thermodynamic stability constant (nominally at 4°C) for the neutral species MnHPVD MnB1 (log K = 47.5 ± 0.5, infinite dilution reference state). This value was larger than that determined for FeHPVD MnB1 (log K = 44.6 ± 0.5). This result has important implications for the metabolism, solubility, speciation, and redox cycling of manganese, as well as for the biologic uptake of iron.

  1. Interactive effects of manganese and/or iron supplementation in adult women

    SciTech Connect

    Davis, C.D.; Greger, J.L. )

    1991-03-15

    Evaluation of the practical significance of manganese-iron interactions has been hampered by the limited methodologies available to assess manganese status. Manganese status has not been monitored longitudinally in control studies with humans. Forty-eight women were recruited for a double blind 125-day supplementation study. After an initial 5-day baseline period, subjects were assigned to one of four treatments: placebo; 30 mg iron as ferrous fumarate daily; 15 mg manganese as an amino acid chelated manganese supplement daily or both the iron and manganese supplements daily. Dietary information, blood and 3-day urine samples were collected during the baseline period and after 20, 55, 85 and 120 days of consuming the supplements. Urinary manganese excretion ranged from 0.11 to 1.40 {mu}g/day. Serum manganese ranged from 0.16 to 1.92 {mu}g/l. Serum was also analyzed for iron, zinc, copper, ferritin and transferrin concentrations. Lymphocytes were isolated and manganese-dependent superoxide dismutase activity was determined as a new method to assess manganese status. Plasma cholesterol ranged from 126 to 229 mg/dl and HDL cholesterol ranged from 31 to 84 mg/dl. Plasma triglycerides were determined and LDL cholesterol was calculated by difference.

  2. Biological and physico-chemical formation of Birnessite during the ripening of manganese removal filters.

    PubMed

    Bruins, Jantinus H; Petrusevski, Branislav; Slokar, Yness M; Huysman, Koen; Joris, Koen; Kruithof, Joop C; Kennedy, Maria D

    2015-02-01

    The efficiency of manganese removal in conventional groundwater treatment consisting of aeration followed by rapid sand filtration, strongly depends on the ability of filter media to promote auto-catalytic adsorption of dissolved manganese and its subsequent oxidation. Earlier studies have shown that the compound responsible for the auto-catalytic activity in ripened filters is a manganese oxide called Birnessite. The aim of this study was to determine if the ripening of manganese removal filters and the formation of Birnessite on virgin sand is initiated biologically or physico-chemically. The ripening of virgin filter media in a pilot filter column fed by pre-treated manganese containing groundwater was studied for approximately 600 days. Samples of filter media were taken at regular time intervals, and the manganese oxides formed in the coating were analysed by Raman spectroscopy, Electron Paramagnetic Resonance (EPR) and Scanning Electron Microscopy (SEM). From the EPR analyses, it was established that the formation of Birnessite was most likely initiated via biological activity. With the progress of filter ripening and development of the coating, Birnessite formation became predominantly physico-chemical, although biological manganese oxidation continued to contribute to the overall manganese removal. The knowledge that manganese removal in conventional groundwater treatment is initiated biologically could be of help in reducing typically long ripening times by creating conditions that are favourable for the growth of manganese oxidizing bacteria. PMID:25463936

  3. Subacute manganese exposure in rats is a neurochemical model of early manganese toxicity

    PubMed Central

    O’Neal, Stefanie L.; Lee, Jang-Won; Zheng, Wei; Cannon, Jason R.

    2014-01-01

    Manganese (Mn) is an essential trace element, but excess exposure leads to accumulation in biological tissues, including the brain. Chronically high Mn levels in the brain are neurotoxic and can result in a progressive, irreversible neurological disorder known as manganism. Manganism has signs and symptoms similar to, but distinguishable from idiopathic Parkinson’s disease, which include both psychological and motor disturbances. Evidence suggests that Mn exposure impacts neurotransmitter levels in the brain. However, it remains unclear if subacute, low-level Mn exposure resulted in alterations in neurotransmitter systems with concomitant behavioral deficits. The current study used high performance liquid chromatography to quantify neurotransmitter levels in rat striatum (STR), substantia nigra (SN), and hippocampus (HP). Subacute Mn exposure via i.p. injection of 15 mg Mn/kg as MnCl2 caused significantly increased dopamine (DA) levels in the STR. The enhancement was accompanied by significantly elevated levels of the DA metabolites, 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), in the STR. In addition, levels of HVA were significantly increased in the SN and HP. These data indicate that subacute, low-level Mn exposure disrupts multiple neurotransmitter systems in the rat brain which may be responsible, in part, for observed locomotor deficits. PMID:25117542

  4. Comparative evaluation of oxidative stress status and manganese availability in plants growing on manganese mine.

    PubMed

    Boojar, Massod Mashhadi Akbar; Goodarzi, Faranak

    2008-11-01

    This study pioneered an approach that determined the effects of excess manganese (Mn) on three species; Datura stramonium, Alhagi camelthorn and Chenopodium ambrosioides. We investigated their levels of Mn, antioxidative enzymes and oxidative damage biomarkers in plants (zone 1) in and outside (zone 2) the Mn mine. The results showed that total and available Mn were at toxic levels for plants growing on zone 1. The Mn levels in each plant species were higher in leaves, stems and roots. Mn was only accumulated significantly in leaf vacuoles of A. camelthorn. Antioxidative enzyme activities of C. ambrosioides and/or D. stramonium in zone 1 were higher in leaves, stems and then in their roots. Malondialdehyde (MDA) and dityrosine levels were insignificantly higher in tissues of the studied plants in zone 1 with respect to zone 2. The roots of studied plants showed significantly higher levels of these biomarkers in comparison with their leaves in zone 1. Accordingly, antioxidative enzymatic response to Mn-stress in D. stramonium and C. ambrosioides and possibly accumulation of Mn in leaf vacuoles of A. camelthorn, protected them from oxidative damages and involved in their tolerance in Mn mine. PMID:18068229

  5. Manganese status of baby pigs born to sows on low or high manganese diets

    SciTech Connect

    Bell, L.; Christianson, S.; Peo, E. Kies, C. )

    1991-03-15

    The main route to manganese (Mn) excretion is in the bile, which normally begins within the first few days of life. The objective of the research was: to determine when Mn excretion commences; to determine the Mn content in liver, heart, kidney and brain of baby pigs born to sows on a high or low Mn diet; and compare these values with sow milk concentration. The Mn concentration in sow milk increases from day 1 to day 3 to day 7 and was consistently higher in the high Mn group vs the low Mn group. Initial excretions of Mn were high at birth and gradually decreased by day 4, then increased slightly on day 7. The Mn excretion values were also consistently higher in the high Mn group vs the low Mn group. There were no significant differences between Mn values in any of the organs from baby pigs in the low or high Mn groups. In both groups there was a significant increase in organ Mn concentration between day of birth and day 7. Thus, baby pigs consuming sow milk of high or low Mn concentrations accumulated the amount of Mn needed for growth and tended to excrete any excess.

  6. Adsorption of selenium by amorphous iron oxyhydroxide and manganese dioxide

    USGS Publications Warehouse

    Balistrieri, L.S.; Chao, T.T.

    1990-01-01

    This work compares and models the adsorption of selenium and other anions on a neutral to alkaline surface (amorphous iron oxyhydroxide) and an acidic surface (manganese dioxide). Selenium adsorption on these oxides is examined as a function of pH, particle concentration, oxidation state, and competing anion concentration in order to assess how these factors might influence the mobility of selenium in the environment. The data indicate that 1. 1) amorphous iron oxyhydroxide has a greater affinity for selenium than manganese dioxide, 2. 2) selenite [Se(IV)] adsorption increases with decreasing pH and increasing particle concentration and is stronger than selenate [Se(VI)] adsorption on both oxides, and 3. 3) selenate does not adsorb on manganese dioxide. The relative affinity of selenate and selenite for the oxides and the lack of adsorption of selenate on a strongly acidic surface suggests that selenate forms outer-sphere complexes while selenite forms inner-sphere complexes with the surfaces. The data also indicate that the competition sequence of other anions with respect to selenite adsorption at pH 7.0 is phosphate > silicate > molybdate > fluoride > sulfate on amorphous iron oxyhydroxide and molybdate ??? phosphate > silicate > fluoride > sulfate on manganese dioxide. The adsorption of phosphate, molybdate, and silicate on these oxides as a function of pH indicates that the competition sequences reflect the relative affinities of these anions for the surfaces. The Triple Layer surface complexation model is used to provide a quantitative description of these observations and to assess the importance of surface site heterogeneity on anion adsorption. The modeling results suggest that selenite forms binuclear, innersphere complexes with amorphous iron oxyhydroxide and monodentate, inner-sphere complexes with manganese dioxide and that selenate forms outer-sphere, monodentate complexes with amorphous iron oxyhydroxide. The heterogeneity of the oxide surface sites

  7. Quantifying manganese and nitrogen cycle coupling in manganese-rich, organic carbon-starved marine sediments: Examples from the Clarion-Clipperton fracture zone

    NASA Astrophysics Data System (ADS)

    Mogollón, José M.; Mewes, Konstantin; Kasten, Sabine

    2016-07-01

    Extensive deep-sea sedimentary areas are characterized by low organic carbon contents and thus harbor suboxic sedimentary environments where secondary (autotrophic) redox cycling becomes important for microbial metabolic processes. Simulation results for three stations in the Eastern Equatorial Pacific with low organic carbon content (<0.5 dry wt %) and low sedimentation rates (10-1-100 mm ky-1) show that ammonium generated during organic matter degradation may act as a reducing agent for manganese oxides below the oxic zone. Likewise, at these sedimentary depths, dissolved reduced manganese may act as a reducing agent for oxidized nitrogen species. These manganese-coupled transformations provide a suboxic conversion pathway of ammonium and nitrate to dinitrogen. These manganese-nitrogen interactions further explain the presence and production of dissolved reduced manganese (up to tens of μM concentration) in sediments with high nitrate (>20 μM) concentrations.

  8. Manganese accumulation in soil and plants along Utah roadways: A possible indication of motor vehicle exhaust pollution

    SciTech Connect

    Lytle, C.M.; Smith, B.N.; McKinnon, C.Z.

    1995-06-01

    An organic manganese compound is currently added to gasoline to replace tetraethyl lead as an antiknock fuel additive in the U.S. and Canada. Combustion exhaust gases contain manganese oxides. Manganese oxides are known to cause various deleterious health effects in experimental animals and humans. A field survey of roadside soil and plants in central Utah revealed that soil manganese concentrations in high traffic areas were up to 100-fold higher than historic lead levels. Soil manganese concentrations were highly correlated with distance from the roadway. In addition, roadside aquatic plants were higher in leaf tissue manganese than herbs or grasses. Submerged and emergent aquatic plants were sensitive bioindicators of manganese contamination. Manganese concentrations in soil and in some plant species along impacted roadsides often exceeded levels known to cause toxicity. We conclude that roadside soil and plants were apparently contaminated by manganese oxides from Mn-containing motor vehicle exhaust.

  9. Manganese accumulation in nail clippings as a biomarker of welding fume exposure and neurotoxicity.

    PubMed

    Sriram, Krishnan; Lin, Gary X; Jefferson, Amy M; Roberts, Jenny R; Andrews, Ronnee N; Kashon, Michael L; Antonini, James M

    2012-01-27

    Occupational exposure to welding fumes (WF) is thought to cause Parkinson's disease (PD)-like neurological dysfunction. An apprehension that WF may accelerate the onset of PD also exists. Identifying reliable biomarkers of exposure and neurotoxicity are therefore critical for biomonitoring and neurological risk characterization of WF exposure. Manganese (Mn) in welding consumables is considered the causative factor for the neurological deficits seen in welders. Hence, we sought to determine if Mn accumulation in blood or nail clippings can be a marker for adverse exposure and neurotoxicity. To model this, rats were exposed by intratracheal instillation to dissolved or suspended fume components collected from gas metal arc-mild steel (GMA-MS) or manual metal arc-hard surfacing (MMA-HS) welding. Trace element analysis revealed selective Mn accumulation in dopaminergic brain areas, striatum (STR) and midbrain (MB), following exposure to the two fumes. This caused dopaminergic abnormality as evidenced by loss of striatal tyrosine hydroxylase (Th; 25-32% decrease) and Parkinson disease (autosomal recessive, early onset) 7 (Park7; 25-46% decrease) proteins. While blood Mn was not detectable, Mn levels in nails strongly correlated with the pattern of Mn accumulation in the striatum (R(2)=0.9386) and midbrain (R(2)=0.9332). Exposure to manganese chloride (MnCl(2)) caused similar Mn accumulation in STR, MB and nail. Our findings suggest that nail Mn has the potential to be a sensitive and reliable biomarker for long-term Mn exposure and associated neurotoxicity. The non-invasive means by which nail clippings can be collected, stored, and transported with relative ease, make it an attractive surrogate for biomonitoring WF exposures in occupational settings. PMID:22085607

  10. Stability of manganese (II) chloride complexes from 25 to 300°C

    NASA Astrophysics Data System (ADS)

    Gammons, C. H.; Seward, T. M.

    1996-11-01

    The stability and stoichiometry of the Mn(II) chloride complexes have been experimentally determined in the temperature range 25 to 300°C. The solubility of AgCl(s) was measured in solutions of fixed HCl concentration (0.01-6.0 m) and varying ΣMn/ΣCl molar ratio (0.0-0.5), following a modification of the method of Ruaya and Seward (1986). The results were regressed to obtain the following smoothed values for the first and second cumulative association constants Our study indicates that Mn 2+ is the dominant species at 25°C, whereas the stabilities of MnCl + and MnCl 20 increase rapidly with temperature. In the absence of competing ligands, the neutral MnCl 20 complex should dominate Mn transport for chloride-rich hydrothermal fluids at or < above 300°C. No evidence was found for complexes of higher ligand number (e.g., MnCl 3- MnCl 42-). Our esults indicate that Mn is more strongly complexed than Fe at elevated temperature. The solubilities of some common manganese-bearing minerals have been calculated as a function of pH, a Cl-, ΣCO 3, and temperature. The minerals rhodonite and rhodocrosite are highly soluble in mildly acidic solutions. Most active geothermal systems are, therefore, expected to be undersaturated with respect to these phases, although they may locally precipitate in response to sudden increases in pH (e.g., during boiling). Mn-silicate minerals will tend to dissolve in solutions undergoing cooling, whereas rhodocrosite exhibits either prograde or retrograde solubility, depending on salinity. Manganese mobilized by hydrothermal fluids may travel considerable distances until contact is ultimately made with an oxidized environment, at which point Mn-oxide minerals will precipitate.

  11. Manganese in biogenic magnetite crystals from magnetotactic bacteria.

    PubMed

    Keim, Carolina N; Lins, Ulysses; Farina, Marcos

    2009-03-01

    Magnetotactic bacteria produce either magnetite (Fe(3)O(4)) or greigite (Fe(3)S(4)) crystals in cytoplasmic organelles called magnetosomes. Whereas greigite magnetosomes can contain up to 10 atom% copper, magnetite produced by magnetotactic bacteria was considered chemically pure for a long time and this characteristic was used to distinguish between biogenic and abiogenic crystals. Recently, it was shown that magnetosomes containing cobalt could be produced by three strains of Magnetospirillum. Here we show that magnetite crystals produced by uncultured magnetotactic bacteria can incorporate manganese up to 2.8 atom% of the total metal content (Fe+Mn) when manganese chloride is added to microcosms. Thus, chemical purity can no longer be taken as a strict prerequisite to consider magnetite crystals to be of biogenic origin. PMID:19187208

  12. Manganese oxide nanowires, films, and membranes and methods of making

    DOEpatents

    Suib, Steven Lawrence; Yuan, Jikang

    2008-10-21

    Nanowires, films, and membranes comprising ordered porous manganese oxide-based octahedral molecular sieves, and methods of making, are disclosed. A single crystal ultra-long nanowire includes an ordered porous manganese oxide-based octahedral molecular sieve, and has an average length greater than about 10 micrometers and an average diameter of about 5 nanometers to about 100 nanometers. A film comprises a microporous network comprising a plurality of single crystal nanowires in the form of a layer, wherein a plurality of layers is stacked on a surface of a substrate, wherein the nanowires of each layer are substantially axially aligned. A free standing membrane comprises a microporous network comprising a plurality of single crystal nanowires in the form of a layer, wherein a plurality of layers is aggregately stacked, and wherein the nanowires of each layer are substantially axially aligned.

  13. Manganese-Enhanced MRI: Biological Applications in Neuroscience

    PubMed Central

    Malheiros, Jackeline Moraes; Paiva, Fernando Fernandes; Longo, Beatriz Monteiro; Hamani, Clement; Covolan, Luciene

    2015-01-01

    Magnetic resonance imaging (MRI) is an excellent non-invasive tool to investigate biological systems. The administration of the paramagnetic divalent ion manganese (Mn2+) enhances MRI contrast in vivo. Due to similarities between Mn2+ and calcium (Ca2+), the premise of manganese-enhanced MRI (MEMRI) is that the former may enter neurons and other excitable cells through voltage-gated Ca2+ channels. As such, MEMRI has been used to trace neuronal pathways, define morphological boundaries, and study connectivity in morphological and functional imaging studies. In this article, we provide a brief overview of MEMRI and discuss recently published data to illustrate the usefulness of this method, particularly in animal models. PMID:26217304

  14. Applications of Manganese-Enhanced Magnetic Resonance Imaging in Neuroscience

    NASA Astrophysics Data System (ADS)

    McCreary, J. Keiko

    Manganese-Enhanced Magnetic Resonance Imaging (MEMRI) has proven itself to be a beneficial technique in the field of Neuroscience. This thesis applies MEMRI to studies in neuroscience by first establishing the limitations concerning the use of MEMRI in live rats. Experiment 1 used an osmotic pump for manganese (Mn) delivery to the lateral ventricles for acquisition of anatomical images using MEMRI. From my knowledge, this was the first method demonstrating slow infusion of Mn to the lateral ventricles. In Experiment 2, MEMRI was used for volumetric analysis the whole brain and hippocampus of prenatally stressed rats. To my knowledge, this study was the first to investigate the effect of generational prenatal stress on the structure of a rat's brain using MEMRI and histology. Additionally, Experiment 2 investigated the use of a subcutaneous osmotic pump to deliver Mn for MEMRI. A summary on the use of MEMRI in Neuroscience concludes this thesis, with a discussion on the methods used and related technical considerations.

  15. First principle study of manganese doped cadmium sulphide sheet

    SciTech Connect

    Kumar, Sanjeev; Kumar, Ashok; Ahluwalia, P. K.

    2014-04-24

    First-principle electronic structure calculations for cadmium sulphide (CdS) sheet in hexagonal phase, with Manganese substitution and addition, as well as including the Cd defects, are investigated. The lattice constants calculated for CdS sheet agrees fairly well with results reported for thin films experimentally. The calculations of total spin density of states and partial density of states in different cases shows substantial magnetic dipole moments acquired by the sheet. A magnetic dipole moment 5.00612 μ{sub B} and band gap of the order 1 eV are found when cadmium atom is replaced by Manganese. The magnetism acquired by the sheet makes it functionally important candidate in many applications.

  16. Compositions containing nucleosides and manganese and their uses

    SciTech Connect

    Daly, Michael J.; Gaidamakova, Elena K.; Matrosova, Vera Y.; Levine, Rodney L.; Wehr, Nancy B.

    2015-11-17

    This invention encompasses methods of preserving protein function by contacting a protein with a composition comprising one or more purine or pyrimidine nucleosides (such as e.g., adenosine or uridine) and an antioxidant (such as e.g., manganese). In addition, the invention encompasses methods of treating and/or preventing a side effect of radiation exposure and methods of preventing a side effect of radiotherapy comprising administration of a pharmaceutically effective amount of a composition comprising one or more purine or pyrimidine nucleosides (such as e.g., adenosine or uridine) and an antioxidant (such as e.g., manganese) to a subject in need thereof. The compositions may comprise D. radiodurans extracts.

  17. Preliminary LIBS analysis of Yucca Mountain manganese oxide minerals

    SciTech Connect

    Blacic, J.; Pettit, D.; Cremers, D.

    1996-01-01

    The licensing and performance of a potential repository at Yucca Mountain will require the characterization of radionuclide sorptive capacity of the host rock, which in turn calls for hundreds of analyses based on extensive sampling or in situ measurements. A rapid method specifically for characterizing the manganese oxide minerals occurring heterogeneously throughout the Yucca Mountain block as fracture surface coatings is needed. Our unique solution is a laser-induced breakdown spectroscopy (LIBS) surface-analysis technique that is usable in the field to produce high-resolution atomic emission spectra. In tests with manganese oxide minerals and fracture surface coatings from a few Yucca Mountain core samples, we used four spectral bands to show that qualitative measurement of all constituent elements except K and Na (in the presence of Mn) is possible with LIBS. Detailed calibration of final hardware will make the system quantitative.

  18. The effect of manganese additions on the reactive evaporation of chromium in Ni–Cr alloys

    SciTech Connect

    Holcomb, G.R.; Alman, D.E.

    2006-05-01

    Chromium is used as an alloy addition in stainless steels and nickel-chromium alloys to form protective chromium oxide scales. Chromium oxide undergoes reactive evaporation in high temperature exposures in the presence of oxygen and/or water vapor. The deposition of gaseous chromium species onto solid oxide fuel cell electrodes can reduce the efficiency of the fuel cell. Manganese additions to the alloy can reduce the activity of chromium in the oxide, either from solid solution replacement of chromium with manganese (at low levels of manganese) or from the formation of manganese-chromium spinels (at high levels of manganese). This reduction in chromium activity leads to a predicted reduction in chromium evaporation by as much as a factor of 35 at 800 °C and 55 at 700 °C. Quantifying the effects of manganese additions on chromium evaporation should aid alloy development of metallic interconnects and balance-of-plant alloys.

  19. Manganese-Mediated Coupling Reaction of Vinylarenes and Aliphatic Alcohols

    PubMed Central

    Zhang, Wei; Wang, Nai-Xing; Bai, Cui-Bing; Wang, Yan-Jing; Lan, Xing-Wang; Xing, Yalan; Li, Yi-He; Wen, Jia-Long

    2015-01-01

    Alcohols and alkenes are the most abundant and commonly used organic building blocks in the large-scale chemical synthesis. Herein, this is the first time to report a novel and operationally simple coupling reaction of vinylarenes and aliphatic alcohols catalyzed by manganese in the presence of TBHP (tert-butyl hydroperoxide). This coupling reaction provides the oxyalkylated products of vinylarenes with good regioselectivity and accomplishes with the principles of step-economies. A possible reaction mechanism has also been proposed. PMID:26470633

  20. Copper/Manganese Cocatalyzed Oxidative Coupling of Vinylarenes with Ketones.

    PubMed

    Lan, Xing-Wang; Wang, Nai-Xing; Zhang, Wei; Wen, Jia-Long; Bai, Cui-Bing; Xing, Yalan; Li, Yi-He

    2015-09-18

    A novel copper/manganese cocatalyzed direct oxidative coupling of terminal vinylarenes with ketones via C(sp(3))-H bond functionalization following C-C bond formation has been developed using tert-butyl hydroperoxide as the radical initiator. Various ketones underwent a free-radical addition of terminal vinylarenes to give the corresponding 1,4-dicarbonyl products with excellent regioselectivity and efficiency through one step. A possible reaction mechanism has been proposed. PMID:26348870

  1. Manganese-Mediated Coupling Reaction of Vinylarenes and Aliphatic Alcohols.

    PubMed

    Zhang, Wei; Wang, Nai-Xing; Bai, Cui-Bing; Wang, Yan-Jing; Lan, Xing-Wang; Xing, Yalan; Li, Yi-He; Wen, Jia-Long

    2015-01-01

    Alcohols and alkenes are the most abundant and commonly used organic building blocks in the large-scale chemical synthesis. Herein, this is the first time to report a novel and operationally simple coupling reaction of vinylarenes and aliphatic alcohols catalyzed by manganese in the presence of TBHP (tert-butyl hydroperoxide). This coupling reaction provides the oxyalkylated products of vinylarenes with good regioselectivity and accomplishes with the principles of step-economies. A possible reaction mechanism has also been proposed. PMID:26470633

  2. Manganese-Mediated Coupling Reaction of Vinylarenes and Aliphatic Alcohols

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Wang, Nai-Xing; Bai, Cui-Bing; Wang, Yan-Jing; Lan, Xing-Wang; Xing, Yalan; Li, Yi-He; Wen, Jia-Long

    2015-10-01

    Alcohols and alkenes are the most abundant and commonly used organic building blocks in the large-scale chemical synthesis. Herein, this is the first time to report a novel and operationally simple coupling reaction of vinylarenes and aliphatic alcohols catalyzed by manganese in the presence of TBHP (tert-butyl hydroperoxide). This coupling reaction provides the oxyalkylated products of vinylarenes with good regioselectivity and accomplishes with the principles of step-economies. A possible reaction mechanism has also been proposed.

  3. Toxicity of manganese. (Latest citations from the NTIS bibliographic database). Published Search

    SciTech Connect

    Not Available

    1994-04-01

    The bibliography contains citations concerning the toxicity, carcinogenicity, environmental pollution, and other hazards and adverse effects of manganese. The detection, characterization, analytical methods, standards, and removal from the environment are considered. These aspects of manganese are dealt with in relation to aquatic and terrestrial flora and fauna, including man. Manganese pollution from mining operations is also discussed. (Contains a minimum of 208 citations and includes a subject term index and title list.)

  4. Contribution of arginase to manganese metabolism of Aspergillus niger.

    PubMed

    Keni, Sarita; Punekar, Narayan S

    2016-02-01

    Aspects of manganese metabolism during normal and acidogenic growth of Aspergillus niger were explored. Arginase from this fungus was a Mn[II]-enzyme. The contribution of the arginase protein towards A. niger manganese metabolism was investigated using arginase knockout (D-42) and arginase over-expressing (ΔXCA-29) strains of A. niger NCIM 565. The Mn[II] contents of various mycelial fractions were found in the order: D-42 strain < parent strain < ΔXCA-29 strain. While the soluble fraction forms 60% of the total mycelial Mn[II] content, arginase accounted for a significant fraction of this soluble Mn[II] pool. Changes in the arginase levels affected the absolute mycelial Mn[II] content but not its distribution in the various mycelial fractions. The A. niger mycelia harvested from acidogenic growth media contain substantially less Mn[II] as compared to those from normal growth media. Nevertheless, acidogenic mycelia harbor considerable Mn[II] levels and a functional arginase. Altered levels of mycelial arginase protein did not significantly influence citric acid production. The relevance of arginase to cellular Mn[II] pool and homeostasis was evaluated and the results suggest that arginase regulation could occur via manganese availability. PMID:26679485

  5. Effect of manganese deficiency on wound healing glycosaminoglycans

    SciTech Connect

    Shetlar, M.R.; Shetlar, C.L. )

    1991-03-15

    Manganese deficiency has been shown to depress proteglycan biosynthesis in the bone matrix in several species. Since the process of wound healing involves increased glycosaminoglycan (GAG) biosynthesis, the authors have made studies of the biosynthesis of GAGS in a wound healing model used in rats fed a diet deficient in manganese. Twelve female albino rats, 22-25 days old were divided into two groups of 6 each. One group was fed the manganese deficient diet; the second group was fed Purina Rodent diet. At maturation these females were mated with males on the Purina diet. Females were maintained on the same respective diets during gestation, delivery and lactation. From the offspring at weaning time, 12 males and 12 females were selected from each diet group. These animals were continued on the respective diets of their dams for 120 days. Each animals was then implanted with an acrylic wound healing cylinder. After 14 days each was injected with 20 microcuies of 1-{sup 14}C-glucosamine. After 24 hours, the cylinders were removed and tissue stripped from the inside of the cylinders. GAGS were separated by cellulose acetate electrophoresis and the radioactivity associated with each fraction determined. Weights of the tissue from the deficient group were significantly decreased. Chondroitin-4-sulfate and the radioactivity associated with this fraction were also decreased in the deficient group.

  6. Transformation of bisphenol A by manganese oxide-coated sand.

    PubMed

    Lin, Kunde; Peng, Yiwen; Huang, Xinwen; Ding, Jiafeng

    2013-03-01

    Oxidative transformation of organic contaminants by manganese oxides was commonly investigated with pure MnO(2) suspension, which deviates from the fact that natural manganese oxides are seldom present as a pure form in the natural environment. In this study, we prepared manganese oxide-coated sand (MOCS) and evaluated its oxidative capacity using bisphenol A (BPA) as the model compound. BPA was transformed by MOCS and the reaction followed an exponential decay model. The reaction was pH dependent and followed the order of pH 4.5>pH 5.5>pH 6.5>pH 7.5>pH 8.6>pH 9.6, indicating that acidic conditions facilitated BPA transformation while basic conditions disfavored the reaction. Coexisting metal ions exhibited inhibitory effects and followed the order of Fe(3+) > Zn(2+) > Cu(2+) > Ca(2+) > Mg(2+) > Na(+). Transformation of BPA by MOCS was much slower than that by pure MnO(2) suspension. However, similar transformation products were identified in both studies, suggesting the same reaction pathways. This work suggests that the reactivity of MnO(2) in the environment might be overestimated if extrapolating the result from the pure MnO(2) suspension because natural MnO(2) is mainly present as coating on the surface of soils and sediments. PMID:22752814

  7. Characterization of Synthetic and Natural Manganese Oxides as Martian Analogues

    NASA Technical Reports Server (NTRS)

    Fox, V. K.; Arvidson, R. E.; Jolliff, B. L.; Carpenter, P. K.; Catalano, J. G.; Hinkle, M. A. G.; Morris, R. V.

    2015-01-01

    Recent discoveries of highly concentrated manganese oxides in Gale Crater and on the rim of Endeavour Crater by the Mars Science Laboratory Curiosity and Mars Exploration Rover Opportunity, respectively, imply more highly oxidizing aqueous conditions than previously recognized. Manganese oxides are a significant environmental indicator about ancient aqueous conditions, provided the phases can be characterized reliably. Manganese oxides are typically fine-grained and poorly crystalline, making the mineral structures difficult to determine, and they generally have very low visible reflectance with few distinctive spectral features in the visible to near infrared, making them a challenge for interpretation from remote sensing data. Therefore, these recent discoveries motivate better characterization using methods available on Mars, particularly visible to near infrared (VNIR) spectroscopy, X-ray diffractometry (XRD), and compositional measurements. Both rovers have complementary instruments in this regard. Opportunity is equipped with its multispectral visible imager, Pancam, and an Alpha Particle X-ray Spectrometer (APXS), and Curiosity has the multispectral Mastcam, ChemCam (laser-induced breakdown spectroscopy and passive spectroscopy), and APXS for in situ characterization, and ChemMin (XRD) for collected samples.

  8. A redox-assisted supramolecular assembly of manganese oxide nanotube

    SciTech Connect

    Tao Li; Sun Chenggao; Fan Meilian; Huang Caijuan; Wu Hailong; Chao Zisheng . E-mail: zschao@yahoo.com; Zhai Hesheng . E-mail: hszhai@xmu.edu.cn

    2006-11-09

    In this paper, we report the hydrothermal synthesis of manganese oxide nanotube from an aqueous medium of pH 7, using KMnO{sub 4} and MnCl{sub 2} as inorganic precursors, polyoxyethylene (10) nonyl phenyl ether (TX-10) a surfactant and acetaldehyde an additive. The characterization of X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and N{sub 2} adsorption at 77 K (BET) reveals that the synthesized manganese oxide nanotube has a mesopore size of ca. 3.65 nm and a wall thickness of ca. 12 nm, with the wall being composed of microporous crystals of monoclinic manganite. The X-ray photoelectron spectroscopy (XPS) result demonstrates a decrease of the binding energy of the Mn{sup 3+} in the manganese oxide nanotube, which may be related to both the nanotubular morphology and the crystalline pore wall. A mechanism of a redox-assisted supramolecular assembly, regulated by acetaldehyde, is postulated.

  9. Manganese formations in the accretionary belts of Japan: Implications for subduction-accretion process in an active convergent margin

    NASA Astrophysics Data System (ADS)

    Nakagawa, M.; Santosh, M.; Maruyama, S.

    2011-08-01

    In the accretionary complexes of Japan, many bedded manganese and iron-manganese ore deposits occur, especially in the Jurassic complexes such as the Chichibu, Tamba, Mino, Ashio and Northern Kitakami belts. The manganese ores in these Jurassic accretionary complexes probably formed from manganese nodule/crust-bearing siliceous sediments on deep-sea floor and were subsequently converted to the manganese ores by metamorphism during the subduction-accretion process. Some of the deposits also show the signatures of younger granitic intrusions. The manganese formations now incorporated within these belts are marker beds of accretionary tectonics associated with plate tectonic processes in convergent margins.

  10. Manganese in occupational arc welding fumes--aspects on physiochemical properties, with focus on solubility.

    PubMed

    Taube, Fabian

    2013-01-01

    Physicochemical properties, such as particle sizes, composition, and solubility of welding fumes are decisive for the bioaccessibility of manganese and thereby for the manganese cytotoxic and neurotoxic effects arising from various welding fumes. Because of the diverse results within the research on welding fume solubility, this article aims to review and discuss recent literature on physicochemical properties of gas metal arc welding, shielded metal arc welding, and flux-cored arc welding fumes, with focus on solubility properties. This article also presents a short introduction to the literature on arc welding techniques, health effects from manganese, and occupational exposure to manganese among welders. PMID:22997412

  11. Strontium and Actinides Removal from Savannah River Site Actual Waste Samples by Freshly Precipitated Manganese Oxide

    SciTech Connect

    Barnes, M.J.

    2003-10-30

    The authors investigated the performance of freshly precipitated manganese oxide and monosodium titanate (MST) for the removal of strontium (Sr) and actinides from actual high-level waste. Manganese oxide precipitation occurs upon addition of a reductant such as formate (HCO2-) or peroxide (H2O2) to a waste solution containing permanganate (MnO4-). Tests described in this document address the capability of manganese oxide treatment to remove Rs, Pu, and Np from actual high-level waste containing elevated concentrations of Pu. Additionally, tests investigate MST (using two unique batches) performance with the same waste for direct comparison to the manganese oxide performance.

  12. Thermodynamic Calculation Study on Effect of Manganese on Stability of Austenite in High Nitrogen Stainless Steels

    NASA Astrophysics Data System (ADS)

    Wang, Qingchuan; Zhang, Bingchun; Yang, Ke

    2016-07-01

    A series of high nitrogen steels were studied by using thermodynamic calculations to investigate the effect of manganese on the stability of austenite. Surprisingly, it was found that the austenite stabilizing ability of manganese was strongly weakened by chromium, but it was strengthened by molybdenum. In addition, with an increase of manganese content, the ferrite stabilizing ability of chromium significantly increased, but that of molybdenum decreased. Therefore, strong interactions exist between manganese and the other alloying elements, which should be the main reason for the difference among different constituent diagrams.

  13. Thermodynamic Calculation Study on Effect of Manganese on Stability of Austenite in High Nitrogen Stainless Steels

    NASA Astrophysics Data System (ADS)

    Wang, Qingchuan; Zhang, Bingchun; Yang, Ke

    2016-05-01

    A series of high nitrogen steels were studied by using thermodynamic calculations to investigate the effect of manganese on the stability of austenite. Surprisingly, it was found that the austenite stabilizing ability of manganese was strongly weakened by chromium, but it was strengthened by molybdenum. In addition, with an increase of manganese content, the ferrite stabilizing ability of chromium significantly increased, but that of molybdenum decreased. Therefore, strong interactions exist between manganese and the other alloying elements, which should be the main reason for the difference among different constituent diagrams.

  14. Oral manganese as an MRI contrast agent for the detection of nociceptive activity.

    PubMed

    Jacobs, Kathleen E; Behera, Deepak; Rosenberg, Jarrett; Gold, Garry; Moseley, Michael; Yeomans, David; Biswal, Sandip

    2012-04-01

    The ability of divalent manganese to enter neurons via calcium channels makes manganese an excellent MRI contrast agent for the imaging of nociception, the afferent neuronal encoding of pain perception. There is growing evidence that nociceptive neurons possess increased expression and activity of calcium channels, which would allow for the selective accumulation of manganese at these sites. In this study, we show that oral manganese chloride leads to increased enhancement of peripheral nerves involved in nociception on T(1)-weighted MRI. Oral rather than intravenous administration was chosen for its potentially better safety profile, making it a better candidate for clinical translation with important applications, such as pain diagnosis, therapy and research. The spared nerve injury (SNI) model of neuropathic pain was used for the purposes of this study. SNI rats were given, sequentially, increasing amounts of manganese chloride (lowest, 2.29 mg/100 g weight; highest, 20.6 mg/100 g weight) with alanine and vitamin D(3) by oral gavage. Compared with controls, SNI rats demonstrated increased signal-to-background ratios on T(1)-weighted fast spin echo MRI, which was confirmed by and correlated strongly with spectrometry measurements of nerve manganese concentration. We also found the difference between SNI and control rats to be greater at 48 h than at 24 h after dosing, indicating increased manganese retention in addition to increased manganese uptake in nociceptive nerves. This study demonstrates that oral manganese is a viable method for the imaging of nerves associated with increased nociceptive activity. PMID:22447731

  15. X-ray-absorption-spectroscopy study of manganese-containing compounds and photosynthetic spinach chloroplasts

    SciTech Connect

    Kirby, J.A.

    1981-05-01

    The manganese sites in chloroplasts, long thought to be involved in photosynthetic oxygen evolution have been examined and partially characterized by x-ray Absorption Spectroscopy (XAS) using synchrotron radiation. The local environment about the manganese atoms is estimated from an analysis of the extended X-ray Absorption Fine Structure (EXAFS). Comparisons with and simulations of the manganese EXAFS for several reference compounds leads to a model in which the chloroplast manganese atoms are contained in a binuclear complex similar to di-u-oxo-tetrakis-(2,2'-bipyridine) dimanganese. It is suggested that the partner metal is another manganese. The bridging ligands are most probably oxygen. The remaining manganese ligands are carbon, oxygen, or nitrogen. A roughly linear correlation between the X-ray K edge onset energy and the coordination charge of a large number of manganese coordination complexes and compounds has been developed. Entry of the chloroplast manganese edge energy onto this correlation diagram establishes that the active pool of manganese is in an oxidation state greater than +2.

  16. Distribution and chemistry of manganese, iron, and suspended particulates in Orca Basin

    NASA Astrophysics Data System (ADS)

    Trefry, John H.; Presley, Bob J.; Keeney-Kennicutt, Wendy L.; Trocine, Robert P.

    1984-06-01

    The intense halocline and redoxcline in the Orca Basin, northwest Gulf of Mexico, induce dramatic water column profiles for manganese, iron, and suspended particulates. Within a 17 m interval, the salinity of the basin water increases from 66 to ≈260 & permil and dissolved oxygen decreases to zero. Midway through this transition zone, concentrations of suspended matter peak at ≈900 μg/liter. Dissolved iron and manganese concentrations in the anoxic brine increase from oceanic values to maxima of 1.6 and 22 mg/liter, respectively. Upward migration of dissolved manganese from the brine leads to production of manganese-rich particles in the slightly oxygenated overlying water.

  17. Molecular imaging of mesothelioma by detection of manganese-superoxide dismutase activity using manganese-enhanced magnetic resonance imaging.

    PubMed

    Hasegawa, Sumitaka; Koshikawa-Yano, Michiko; Saito, Shigeyoshi; Morokoshi, Yukie; Furukawa, Takako; Aoki, Ichio; Saga, Tsuneo

    2011-05-01

    Malignant mesothelioma (MM) is a fatal malignancy with a rapidly increasing incidence in industrialized countries because of the widespread use of asbestos in the past centuries. Early diagnosis of MM is critical for a better prognosis, but this is often difficult because of the lack of disease-specific diagnostic imaging. Here, we report that manganese-enhanced magnetic resonance imaging (MEMRI) represents a promising approach for a more selective mesothelioma imaging by monitoring a high-level expression of manganese-superoxide dismutase (Mn-SOD), which is observed in many MM. We found that most human MM cells overexpressed Mn-SOD protein compared with human mesothelial cells and that NCI-H226 human MM cells highly expressed Mn-SOD and augmented Mn accumulation when loaded with manganese chloride (MnCl(2)). The cells showed marked T(1)-signal enhancement on in vitro MRI after incubation with MnCl(2) because of the T(1) shortening effect of Mn(2+). H226 subcutaneous tumor was preferentially enhanced compared with a lung adenocarcinoma cell tumor and another human MM cell tumor in MnCl(2)-enhanced T(1)-weighted MR image (T(1)WI), correlating with their respective Mn-SOD expression levels. Moreover, in a more clinically relevant setting, H226 xenografted pleural tumor was markedly enhanced and readily detected by MEMRI using manganese dipyridoxyl diphosphate (MnDPDP), a clinically used contrast agent, as well as MnCl(2). Therefore, we propose that MEMRI can be a potentially powerful method for noninvasive detection of MM, with high spatial resolution and marked signal enhancement, by targeting Mn-SOD. PMID:20617513

  18. Evaluation of manganese uptake and toxicity in mouse brain during continuous MnCl2 administration using osmotic pumps.

    PubMed

    Sepúlveda, M R; Dresselaers, T; Vangheluwe, P; Everaerts, W; Himmelreich, U; Mata, A M; Wuytack, F

    2012-01-01

    Manganese is a vital element and cofactor of many key enzymes, but it is toxic at high levels, causing pronounced disturbances in the mammalian brain. Magnetic resonance imaging (MRI) studies using manganese ions as a paramagnetic contrast agent are often limited by the neurotoxicity of Mn(2+) . In this work, we have explored a new in vivo model to study Mn(2+) uptake, distribution and neurotoxicity in mice by subcutaneous implantation of mini-osmotic pumps delivering MnCl(2) continuously for 21 days. Fractionated injections can reduce the toxicity; however, constant administration at very low doses using osmotic pumps caused a substantial effect on the T(1) contrast in MRI while reducing toxicity. Manganese-enhanced MRI documented fast but reversible Mn(2+) deposition largely in glomerular and mitral cell layers of the olfactory bulb, in the CA3 area of the hippocampus, and in the gray matter of the cerebellum. Mn(2+) accumulated as early as the first days after implantation, with a fast dispersal 9 days after stopping a 12-days Mn(2+) exposure. Prominent Mn(2+) accumulation was also seen in salivary glands and in the endocrine thyroid and posterior pituitary gland. These structures with enhanced Mn(2+) accumulation correlated well with those showing high expression of the secretory pathway Ca(2+) /Mn(2+) -ATPase (SPCA1), i.e. a transporter that could take part in Mn(2+) detoxification. Our new experimental model for continuous low-dosage administration of Mn(2+) is an easy alternative for enhancing Mn(2+) -based contrast in MEMRI studies, and might provide insight into the etiology of neuropathologies resulting from chronic Mn(2+) exposure in vivo. PMID:22649049

  19. High-performance lithium storage in an ultrafine manganese fluoride nanorod anode with enhanced electrochemical activation based on conversion reaction.

    PubMed

    Rui, Kun; Wen, Zhaoyin; Huang, Xiao; Lu, Yan; Jin, Jun; Shen, Chen

    2016-02-01

    A facile, one-step solvothermal reaction route for the preparation of manganese fluoride nanorods is successfully developed using manganese(II) chloride tetrahydrate (MnCl2·4H2O) as the manganese source and the ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate (BmimBF4) as the fluorine source. X-ray diffraction, field-emission scanning electron microscopy and high-resolution transmission electron microscopy (HRTEM) are conducted to characterize the structural and microstructural properties of the synthesized MnF2. The pure-phase tetragonal MnF2 displays nanorod-like morphology with a diameter of about 20 nm and a length of several hundreds of nanometers. The electrochemical performance of the MnF2 nanorod anode for rechargeable lithium batteries is investigated. A reversible discharge capacity as high as 443 mA h g(-1) at 0.1 C is obtained for the lithium uptake reaction with an initial discharge plateau around 0.7 V. The striking enhancement in electrochemical Li storage performance in ultrafine MnF2 nanorods can be attributed to the small diameters of the nanorods and efficient one-dimensional electron transport pathways. Long cycle performance for 2000 cycles at 10 C with a stabilized capacity of about 430 mA h g(-1) after activation is also achieved. Furthermore, lithiated and delithiated MnF2 anodes are analyzed with HRTEM to elucidate the conversion mechanism for the electrochemical reaction of MnF2 nanorods with Li at a microscopic level. PMID:26766389

  20. Physical Characterization of the Manganese-sensing Pneumococcal Surface Antigen Repressor (PsaR) from Streptococcus pneumoniae*

    PubMed Central

    Lisher, John P.; Higgins, Khadine A.; Maroney, Michael J.; Giedroc, David P.

    2013-01-01

    Transition metals, including manganese, are required for proper virulence and persistence of many pathogenic bacteria. In Streptococcus pneumoniae (Spn), manganese homeostasis is controlled by a high affinity Mn(II) uptake complex, PsaBCA, and a constitutively expressed efflux transporter, MntE. PsaBCA expression is transcriptionally regulated by the DtxR/MntR family metalloregulatory protein pneumococcal surface antigen repressor (PsaR) in Spn. Here, we present a comprehensive analysis of the metal and DNA-binding properties of PsaR. PsaR is a homodimer in the absence and presence of metals and binds two manganese or zinc per protomer (four per dimer) in two pairs of structurally distinct sites, termed site 1 and site 2. Site 1 is likely filled with Zn(II) in vivo (KZn1≥1013 M−1; KMn1≈108 M−1). The Zn(II)-site 1 complex adopts a pentacoordinate geometry by x-ray absorption spectroscopy containing a single cysteine, and appears analogous to the Cd(II) site observed in S. gordonii ScaR. Site 1 is necessary but not sufficient for full positive allosteric activation of DNA operator binding by metals as measured by ΔGc, the allosteric coupling free energy, since mutants in site 1 show intermediate ΔGc. Site 2 is the primary regulatory site and governs specificity for Mn(II) over Zn(II) in PsaR, with ΔGcZn,Mn>>ΔGcZn,Zn despite the fact that Zn(II) binds site 2 with 40-fold higher affinity relative to Mn(II), i.e., KZn2>KMn2. Mutational studies reveal that Asp7 in site 2 is a critical ligand for Mn(II)-dependent allosteric activation of DNA binding. These findings are discussed in the context of other well-studied DtxR/MntR Mn(II)/Fe(II) metallorepressors. PMID:24067066

  1. Iron and manganese oxide mineralization in the Pacific

    USGS Publications Warehouse

    Hein, J.R.; Koschinsky, A.; Halbach, P.; Manheim, F. T.; Bau, M.; Kang, J.-K.; Lubick, N.

    1997-01-01

    Iron, manganese, and iron-manganese deposits occur in nearly all geomorphologic and tectonic environments in the ocean basins and form by one or more of four processes: (1) hydrogenetic precipitation from cold ambient seawater, (2) precipitation from hydrothermal fluids, (3) precipitation from sediment pore waters that have been modified from bottom water compositions by diagenetic reactions in the sediment column and (4) replacement of rocks and sediment. Iron and manganese deposits occur in five forms: nodules, crusts, cements, mounds and sediment-hosted stratabound layers. Seafloor oxides show a wide range of compositions from nearly pure iron to nearly pure manganese end members. Fe/Mn ratios vary from about 24 000 (up to 58% elemental Fe) for hydrothermal seamount ironstones to about 0.001 (up to 52% Mn) for hydrothermal stratabound manganese oxides from active volcanic arcs. Hydrogenetic Fe-Mn crusts that occur on most seamounts in the ocean basins have a mean Fe/Mn ratio of 0.7 for open-ocean seamount crusts and 1.2 for continental margin seamount crusts. Fe-Mn nodules of potential economic interest from the Clarion-Clipperton Zone have a mean Fe/Mn ratio of 0.3, whereas the mean ratio for nodules from elsewhere in the Pacific is about 0.7. Crusts are enriched in Co, Ni and Pt and nodules in Cu and Ni, and both have significant concentrations of Pb, Zn, Ba, Mo, V and other elements. In contrast, hydrothermal deposits commonly contain only minor trace metal contents, although there are many exceptions, for example, with Ni contents up to 0.66%, Cr to 1.2%, and Zn to 1.4%. Chondrite-normalized REE patterns generally show a positive Ce anomaly and abundant ??REEs for hydrogenetic and mixed hydrogenetic-diagenetic deposits, whereas the Ce anomaly is negative for hydrothermal deposits and ??REE contents are low. However, the Ce anomaly in crusts may vary from strongly positive in East Pacific crusts to slightly negative in West Pacific crusts, which may reflect

  2. Manganese oxide nanosheets and a 2D hybrid of graphene-manganese oxide nanosheets synthesized by liquid-phase exfoliation

    NASA Astrophysics Data System (ADS)

    Coelho, João; Mendoza-Sánchez, Beatriz; Pettersson, Henrik; Pokle, Anuj; McGuire, Eva K.; Long, Edmund; McKeon, Lorcan; Bell, Alan P.; Nicolosi, Valeria

    2015-06-01

    Manganese oxide nanosheets were synthesized using liquid-phase exfoliation that achieved suspensions in isopropanol (IPA) with concentrations of up to 0.45 mg ml-1. A study of solubility parameters showed that the exfoliation was optimum in N,N-dimethylformamide followed by IPA and diethylene glycol. IPA was the solvent of choice due to its environmentally friendly nature and ease of use for further processing. For the first time, a hybrid of graphene and manganese oxide nanosheets was synthesized using a single-step co-exfoliation process. The two-dimensional (2D) hybrid was synthesized in IPA suspensions with concentrations of up to 0.5 mg ml-1 and demonstrated stability against re-aggregation for up to six months. The co-exfoliation was found to be a energetically favorable process in which both solutes, graphene and manganese oxide nanosheets, exfoliate with an improved yield as compared to the single-solute exfoliation procedure. This work demonstrates the remarkable versatility of liquid-phase exfoliation with respect to the synthesis of hybrids with tailored properties, and it provides proof-of-concept ground work for further future investigation and exploitation of hybrids made of two or more 2D nanomaterials that have key complementary properties for various technological applications.

  3. The kinetics of iodide oxidation by the manganese oxide mineral birnessite

    USGS Publications Warehouse

    Fox, P.M.; Davis, J.A.; Luther, G. W., III

    2009-01-01

    The kinetics of iodide (I-) and molecular iodine (I2) oxidation by the manganese oxide mineral birnessite (??-MnO2) was investigated over the pH range 4.5-6.25. I- oxidation to iodate (IO3-) proceeded as a two-step reaction through an I2 intermediate. The rate of the reaction varied with both pH and birnessite concentration, with faster oxidation occurring at lower pH and higher birnessite concentration. The disappearance of I- from solution was first order with respect to I- concentration, pH, and birnessite concentration, such that -d[I-]/dt = k[I-][H+][MnO2], where k, the third order rate constant, is equal to 1.08 ?? 0.06 ?? 107 M-2 h-1. The data are consistent with the formation of an inner sphere I- surface complex as the first step of the reaction, and the adsorption of I- exhibited significant pH dependence. Both I2, and to a lesser extent, IO3- sorbed to birnessite. The results indicate that iodine transport in mildly acidic groundwater systems may not be conservative. Because of the higher adsorption of the oxidized I species I2 and IO3-, as well as the biophilic nature of I2, redox transformations of iodine must be taken into account when predicting I transport in aquifers and watersheds.

  4. Role of the node in controlling traffic of cadmium, zinc, and manganese in rice

    PubMed Central

    Yamaguchi, Noriko; Ishikawa, Satoru; Abe, Tadashi; Baba, Koji; Terada, Yasuko

    2012-01-01

    Heavy metals are transported to rice grains via the phloem. In rice nodes, the diffuse vascular bundles (DVBs), which enclose the enlarged elliptical vascular bundles (EVBs), are connected to the panicle and have a morphological feature that facilitates xylem-to-phloem transfer. To find a mechanism for restricting cadmium (Cd) transport into grains, the distribution of Cd, zinc (Zn), manganese (Mn), and sulphur (S) around the vascular bundles in node I (the node beneath the panicle) of Oryza sativa ‘Koshihikari’ were compared 1 week after heading. Elemental maps of Cd, Zn, Mn, and S in the vascular bundles of node I were obtained by synchrotron micro-X-ray fluorescence spectrometry and electron probe microanalysis. In addition, Cd K-edge microfocused X-ray absorption near-edge structure analyses were used to identify the elements co-ordinated with Cd. Both Cd and S were mainly distributed in the xylem of the EVB and in the parenchyma cell bridge (PCB) surrounding the EVB. Zn accumulated in the PCB, and Mn accumulated around the protoxylem of the EVB. Cd was co-ordinated mainly with S in the xylem of the EVB, but with both S and O in the phloem of the EVB and in the PCB. The EVB in the node retarded horizontal transport of Cd toward the DVB. By contrast, Zn was first stored in the PCB and then efficiently transferred toward the DVB. Our results provide evidence that transport of Cd, Zn, and Mn is differentially controlled in rice nodes, where vascular bundles are functionally interconnected. PMID:22291135

  5. Visible and near-infrared spectra of manganese oxides: Detecting high manganese phases in Curiosity Mastcam multispectral images

    NASA Astrophysics Data System (ADS)

    Hardgrove, C. J.; Lanza, N.; Bell, J. F., III; Wiens, R. C.; Johnson, J. R.; Morris, R. V.

    2014-12-01

    The Mars Science Laboratory Curiosity rover's Chemcam instrument has identified manganese in relatively high abundance on several rock surfaces. The manganese abundances are several orders of magnitude greater than has been previously identified on Mars, indicating the presence of a manganese-rich phase. Although the specific phase has yet to be identified, these results suggest that the martian surface may have been much more highly oxidizing than has previously been recognized. The presence of a manganese-rich phase could provide an additional indicator of habitable aqueous environments. Given the importance of manganese for understanding past habitability, and the high abundances identified with Chemcam, we investigate the utility of using Mastcam multispectral imaging surveys to identify areas for subsequent detailed analysis with Chemcam. Vempati et al. showed that Mn3+ affect the reflectance spectra of Mn-bearing minerals. Specifically, relatively weak features due to electronic transitions and crystal field effects are observed in Mn-enriched hematites and geothites at 454, 554, 596 and 700 nm. The Mastcam-34 medium angle camera has filter band-passes at 550, 675 and 750nm, and we will explore the utility of using these bands (or combinations thereof) to determine if there is a contribution of Mn-bearing phases on spectra, specifically those that have been identified as having elevated Mn with Chemcam. The most common Mn-bearing mineral phase in terrestrial varnishes, Birnessite, has charge-transfer features that are similar to Fe-oxides but are centered at slightly longer wavelength band positions. Longer wavelength features are also common for other Mn-oxides, and this could be used to distinguish these phases from other Fe-oxide components. In this study we will present visible to near-infrared (0.4 - 3 µm) reflectance spectra on a suite of Mn-oxide laboratory standards. The set of standards includes Mn-oxide abundances that vary from less than 1 up to

  6. Spatial and Geochemical Techniques to Improve Exposure Assessment of Manganese in Windsor, Ontario

    NASA Astrophysics Data System (ADS)

    Nugent Ayres, Michelle V.

    This study was conducted to investigate the urban geochemistry of the city of Windsor (Ontario) and to provide added source apportionment information to work being carried out by the Canadian government. The goal of this study was to investigate the distribution, spatial variation and sources of manganese in urban Windsor soil. The literature indicates that human exposure to high levels of manganese, via inhalation, can cause respiratory and/or neurological effects. At the outset of the present study it was first hypothesized that vehicular traffic was the dominant source of anthropogenic manganese. An alternative hypothesis was that there were multiple anthropogenic sources of manganese in Windsor. The sample collection scheme was designed to determine (1) the current and background soil concentrations of manganese in Windsor, (2) the spatial distribution of manganese in order to reveal sources of manganese, and (3) the manganese content of moss-sequestered airborne particles, which can potentially deposit onto the soil surface, using low-technology biomonitoring. The first phase of the study consisted of a preliminary soil survey which identified elevated areas of soil manganese concentrations. During this survey, the field efficiency of a field portable X-ray fluorescence (FPXRF) instrument, as well as sample preparation methods were evaluated. Efficiency of the FPXRF was determined by comparison to ICP-MS, a traditional trace element analysis method. The preliminary soil survey identified several areas of elevated (ranging from 884 to 2390 ppm) soil manganese which were further investigated during the second, more complete, soil survey. The moss biomonitoring technique of using moss bags was used to collect airborne particles for semi-quantitative analysis. Analysis of soil samples included total manganese and other trace elements, pH, moisture and carbon content, and manganese speciation. Urban Windsor soil manganese distribution revealed both natural and

  7. Depositional process for the Triassic-Jurassic stratiform manganese deposits in the Chichibu Belt, Southwest Japan.

    NASA Astrophysics Data System (ADS)

    Tomimatsu, Y.; Onoue, T.

    2015-12-01

    The chert-hosted manganese deposits have been known to occur in the Triassic to Jurassic chert or chert-greenstone complex within a Jurassic accretionary complex in Japan. In order to reveal the origin of these manganese deposits, we investigated the stratigraphy, age and geochemistry of manganese deposits from the Triassic to Jurassic bedded chert succession of the Chichibu Belt, defined as a Jurassic subduction-generated accretionary complex in Southwest Japan. The Triassic to Jurassic bedded cherts in the Chichibu Belt are considered to be deep-sea sediments that accumulated in an open-ocean realm of the Panthalassa Ocean. Our biostratigraphic analysis of radiolarians reveals that the stratiform manganese deposits intercalated in the bedded cherts were deposited in the Late Triassic and Early Jurassic. Upper Triassic manganese deposit occurs associated with the massive cherts which appear to have been formed by hydrothermal activity. The red bedded chert above the manganese deposit yields radiolarian fossils, including Trialatus longicornutus and Poulpus carcharus. These radiolarians indicate that age of manganese deposits can be correlated with the late Carnian age. Lower Jurassic manganese deposit occurs intercalated within the gray to dark gray bedded cherts. Detailed biostratigraphic analysis of radiolarians reveals that manganese deposit is embedded in the upper Pliensbachian to Toarcian (Trillus elkhornensis Zone). Chemical compositions of Upper Triassic deposits are characterized by enrichments in Mn and depletion of Co, Ni and Zn. These geochemical features are similar to those of modern submarine hydrothermal manganese deposits from hydrothermal activity. In contrast, lower Jurassic manganese deposits were triggered by an influx of warm, saline and oxic water into a stagnant deep ocean floor basin. It is likely that the deposits are considered to have formed by oceanic anoxic event.

  8. Manganese accumulation in hair and teeth as a biomarker of manganese exposure and neurotoxicity in rats.

    PubMed

    Liang, Guiqiang; Zhang, Li'e; Ma, Shuyan; Lv, Yingnan; Qin, Huiyan; Huang, Xiaowei; Qing, Li; Li, Qin; Chen, Kangcheng; Xiong, Feng; Ma, Yifei; Nong, Jie; Yang, Xiaobo; Zou, Yunfeng

    2016-06-01

    Manganese (Mn) is an essential trace element to humans. However, excessive Mn causes cognitive impairment resulting from injury to the central nervous system within the hippocampus. No ideal biomarker is currently available for evaluating Mn exposure and associated neurotoxicity in the body. Hence, this study used Mn levels in the serum (MnS), teeth (MnT), and hair (MnH) as biomarkers for evaluating the association between Mn exposure and cognitive impairment in Mn-treated rats. A total of 32 male Sprague-Dawley rats were randomly divided into four groups, received 0, 5, 10, and 20 mg/(kg day) of MnCl2·4H2O for 5 days a week for 18 weeks, respectively. Lifetime Mn cumulative dose (LMCD) was used to evaluate external Mn exposure. Hippocampus, serum, teeth, and hair specimens were collected from the rats for Mn determination by graphite furnace atomic absorption spectrometry. Learning and memory functions were assessed using the Morris water maze test. Results showed that chronic Mn exposure increased the hippocampus (MnHip), MnS, MnT, and MnH levels, as well as impaired learning and memory function in rats. MnHip, MnT, and MnH levels were positively correlated with LMCD (r = 0.759, r = 0.925, and r = 0.908, respectively; p < 0.05), escape latency (r = 0.862, r = 0.716, and r = 0.814, respectively; p < 0.05), and the number of platform crossings (r = -0.734, r = -0.514, and r = -0.566, respectively; p < 0.05). No association was observed between MnS levels and the number of platform crossings (r = -0.286, p > 0.05). Thus, MnT and MnH detected long-term low-dose Mn exposure. These parameters can be reliable biomarkers for Mn exposure and associated neurotoxicity in Mn-treated rats. PMID:26976011

  9. Assessment of the permissible exposure level to manganese in workers exposed to manganese dioxide dust.

    PubMed Central

    Roels, H A; Ghyselen, P; Buchet, J P; Ceulemans, E; Lauwerys, R R

    1992-01-01

    The prevalence of neuropsychological and respiratory symptoms, lung ventilatory parameters, neurofunctional performances (visual reaction time, eye-hand coordination, hand steadiness, audioverbal short term memory), and several biological parameters (calcium, iron, luteinising hormone (LH), follicle stimulating hormone (FSH), and prolactin concentrations in serum, blood counts, manganese (Mn) concentration in blood and in urine) were examined in a group of workers (n = 92) exposed to MnO2 dust in a dry alkaline battery factory and a matched control group (n = 101). In the battery plant, the current exposure of the workers to airborne Mn was measured with personal samplers and amounted on average (geometric mean) to 215 and 948 micrograms Mn/m3 for respirable and total dust respectively. For each worker, the lifetime integrated exposure to respirable and total airborne Mn dust was also assessed. The geometric means of the Mn concentrations in blood (MnB) and in urine (MnU) were significantly higher in the Mn exposed group than in the control group (MnB 0.81 v 0.68 microgram/100 ml; MnU 0.84 v 0.09 microgram/g creatinine). On an individual basis, MnU and MnB were not related to various external exposure parameters (duration of exposure, current exposure, or lifetime integrated exposure to airborne Mn). On a group basis, a statistically significant association was found between MnU and current Mn concentrations in air. No appreciable difference between the exposed and the control workers was found with regard to the other biological measurements (calcium, LH, FSH, and prolactin in serum). Although the erythropoietic parameters and serum iron concentration were in the normal range for both groups, there was a statistically significant trend towards lower values in the Mn exposed workers. The prevalences of reported neuropsychological and respiratory symptoms, the lung function parameters, and the audioverbal short term memory scores did not differ between the control

  10. Past occupational exposure to airborne manganese in a manganese alloy plant.

    PubMed

    Baldwin, Mary; Bouchard, Maryse; Larribe, Fabrice; Mergler, Donna

    2008-07-01

    A retrospective exposure assessment of a group of manganese (Mn) alloy workers was performed in conjunction with a 2004 follow-up study, 14 years after cessation of exposure, to evaluate the long-term effects of occupational Mn exposure on neurobehavioral functions. The ferro- and silico-Mn alloy plant opened in 1973 and closed in 1991. The airborne total Mn (TMn) exposures for job groupings were established using personal sampling data from a 1991 industrial hygiene survey. Historical short-term total dust (TDust) data were used to estimate past TDust exposure for job groupings and plant areas. Relationships between Mn content and TDust from the 1991 survey, supported by sparse historical data, were used to estimate TMn content in the historical TDust data. Results showed past personal TDust exposure levels much higher than those found in 1991. Changes in TDust levels and corresponding TMn levels were a function of changes in ventilation, work practices, and operations, not of product (ferro- or silico-Mn). Relationships between TMn and respirable Mn (RMn) from area sampling in 1991 were used to estimate RMn exposure for the job groups. Work histories for 112 workers were developed from payroll records, questionnaires, and interviews and combined with Mn exposure estimates to develop cumulative exposure indices (CEIs). The TMn CEI ranged from 0.27 mg/m(3)x years to 100.24 mg/m(3)x years, with an AM of 24.40 mg/m(3)x years and a GM of 14.06 mg/m(3)x years. The RMn CEI had an AM of 2.95 mg/m(3)x years and a GM of 1.78 mg/m(3)x years with a range of 0.05-12.03 mg/m(3)x years. Overall average TMn exposure intensity, the TMn CEI divided by time worked in years for each worker, had an AM of 1.6 mg Mn/m(3), a GM of 1.0 mg Mn/m(3), range 0.02-6.2 6 mg Mn/m(3). The results of the 2004 follow-up study showed several concentration-response relationships between TMn CEI and neurobehavioral outcomes, which suggest that increase in cumulative TMn exposure level has long

  11. Growth and Dissolution of Iron and Manganese Oxide Films

    SciTech Connect

    Scot T. Martin

    2008-12-22

    Growth and dissolution of Fe and Mn oxide films are key regulators of the fate and transport of heavy metals in the environment, especially during changing seasonal conditions of pH and dissolved oxygen. The Fe and Mn are present at much higher concentrations than the heavy metals, and, when Fe and Mn precipitate as oxide films, heavy metals surface adsorb or co-precipitate and are thus essentially immobilized. Conversely, when the Fe and Mn oxide films dissolve, the heavy metals are released to aqueous solution and are thus mobilized for transport. Therefore, understanding the dynamics and properties of Fe and Mn oxide films and thus on the uptake and release of heavy metals is critically important to any attempt to develop mechanistic, quantitative models of the fate, transport, and bioavailablity of heavy metals. A primary capability developed in our earlier work was the ability to grow manganese oxide (MnO{sub x}) films on rhodochrosite (MnCO{sub 3}) substrate in presence of dissolved oxygen under mild alkaline conditions. The morphology of the films was characterized using contact-mode atomic force microscopy. The initial growth began by heteroepitaxial nucleation. The resulting films had maximum heights of 1.5 to 2 nm as a result of thermodynamic constraints. Over the three past years, we have investigated the effects of MnO{sub x} growth on the interactions of MnCO{sub 3} with charged ions and microorganisms, as regulated by the surface electrical properties of the mineral. In 2006, we demonstrated that MnO{sub x} growth could induce interfacial repulsion and surface adhesion on the otherwise neutral MnCO{sub 3} substrate under environmental conditions. Using force-volume microscopy (FVM), we measured the interfacial and adhesive forces on a MnO{sub x}/MnCO{sub 3} surface with a negatively charged silicon nitride tip in a 10-mM NaNO3 solution at pH 7.4. The interfacial force and surface adhesion of MnOx were approximately 40 pN and 600 pN, respectively

  12. The Escherichia coli Small Protein MntS and Exporter MntP Optimize the Intracellular Concentration of Manganese

    PubMed Central

    Martin, Julia E.; Waters, Lauren S.; Storz, Gisela; Imlay, James A.

    2015-01-01

    Escherichia coli does not routinely import manganese, but it will do so when iron is unavailable, so that manganese can substitute for iron as an enzyme cofactor. When intracellular manganese levels are low, the cell induces the MntH manganese importer plus MntS, a small protein of unknown function; when manganese levels are high, the cell induces the MntP manganese exporter and reduces expression of MntH and MntS. The role of MntS has not been clear. Previous work showed that forced MntS synthesis under manganese-rich conditions caused bacteriostasis. Here we find that when manganese is scarce, MntS helps manganese to activate a variety of enzymes. Its overproduction under manganese-rich conditions caused manganese to accumulate to very high levels inside the cell; simultaneously, iron levels dropped precipitously, apparently because manganese-bound Fur blocked the production of iron importers. Under these conditions, heme synthesis stopped, ultimately depleting cytochrome oxidase activity and causing the failure of aerobic metabolism. Protoporphyrin IX accumulated, indicating that the combination of excess manganese and iron deficiency had stalled ferrochelatase. The same chain of events occurred when mutants lacking MntP, the manganese exporter, were exposed to manganese. Genetic analysis suggested the possibility that MntS exerts this effect by inhibiting MntP. We discuss a model wherein during transitions between low- and high-manganese environments E. coli uses MntP to compensate for MntH overactivity, and MntS to compensate for MntP overactivity. PMID:25774656

  13. Zinc and Manganese Chelation by Neutrophil S100A8/A9 (Calprotectin) Limits Extracellular Aspergillus fumigatus Hyphal Growth and Corneal Infection.

    PubMed

    Clark, Heather L; Jhingran, Anupam; Sun, Yan; Vareechon, Chairut; de Jesus Carrion, Steven; Skaar, Eric P; Chazin, Walter J; Calera, José Antonio; Hohl, Tobias M; Pearlman, Eric

    2016-01-01

    Calprotectin, a heterodimer of S100A8 and S100A9, is an abundant neutrophil protein that possesses antimicrobial activity primarily because of its ability to chelate zinc and manganese. In the current study, we showed that neutrophils from calprotectin-deficient S100A9(-/-) mice have an impaired ability to inhibit Aspergillus fumigatus hyphal growth in vitro and in infected corneas in a murine model of fungal keratitis; however, the ability to inhibit hyphal growth was restored in S100A9(-/-) mice by injecting recombinant calprotectin. Furthermore, using recombinant calprotectin with mutations in either the Zn and Mn binding sites or the Mn binding site alone, we show that both zinc and manganese binding are necessary for calprotectin's antihyphal activity. In contrast to hyphae, we found no role for neutrophil calprotectin in uptake or killing of intracellular A. fumigatus conidia either in vitro or in a murine model of pulmonary aspergillosis. We also found that an A. fumigatus ∆zafA mutant, which demonstrates deficient zinc transport, exhibits impaired growth in infected corneas and following incubation with neutrophils or calprotectin in vitro as compared with wild-type. Collectively, these studies demonstrate a novel stage-specific susceptibility of A. fumigatus to zinc and manganese chelation by neutrophil-derived calprotectin. PMID:26582948

  14. Effects of copper on the photosynthesis of intact chloroplasts: interaction with manganese.

    PubMed

    Pádua, Mário; Cavaco, Ana M; Aubert, Serge; Bligny, Richard; Casimiro, Adalcina

    2010-03-01

    Highly purified, intact chloroplasts were prepared from pea (Pisum sativum L.) and spinach (Spinacia oleracea L.) following an identical procedure, and were used to investigate the cupric cation inhibition on the photosynthetic activity. In both species, copper inhibition showed a similar inhibitor concentration that decreases the enzyme activity by 50% (IC(50) approximately 1.8 microM) and did not depend on the internal or external phosphate (Pi) concentration, indicating that copper did not interact with the Pi translocator. Fluorescence analysis suggested that the presence of copper did not facilitate photoinhibition, because there were no changes in maximal fluorescence (F(m)) nor in basal fluorescence (F(o)) of copper-treated samples. The electron transport through the photosystem II (PSII) was also not affected (operating efficiency of PSII-F'v/F'm similar in all conditions). Yet, under Cu(2+) stress, the proportion of open PSII reaction centers was dramatically decreased, and the first quinone acceptor (Q(A)) reoxidation was fully inhibited, as demonstrated by the constant photochemical quenching (q(P)) along experiment time. The quantum yield of PSII electron transport (Phi(PSII)) was also clearly affected by copper, and therefore reduced the photochemistry efficiency. Manganese, when added simultaneously with copper, delayed the inhibition, as measured by oxygen evolution and chlorophyll fluorescence, but neither reversed the copper effect when added to copper-inhibited plastids, nor prevented the inhibition of the Hill activity of isolated copper-treated thylakoids. Our results suggest that manganese competed with copper to penetrate the chloroplast envelope. This competition seems to be specific because other divalent cations e.g. magnesium and calcium, did not interfere with the copper action in intact chloroplasts. All results do suggest that, under these conditions, the stroma proteins, such as the Calvin-Benson cycle enzymes or others are the most

  15. Element substitution by living organisms: the case of manganese in mollusc shell aragonite

    NASA Astrophysics Data System (ADS)

    Soldati, Analia L.; Jacob, Dorrit E.; Glatzel, Pieter; Swarbrick, Janine C.; Geck, Jochen

    2016-03-01

    Determining the manganese concentration in shells of freshwater bivalves provides a unique way to obtain information about climate and environmental changes during time-intervals that pre-date instrumental data records. This approach, however, relies on a thorough understanding of how manganese is incorporated into the shell material –a point that remained controversial so far. Here we clarify this issue, using state-of-the-art X-ray absorption and X-ray emission spectroscopy in combination with band structure calculations. We verify that in the shells of all studied species manganese is incorporated as high-spin Mn2+, i.e. manganese always has the same valence as calcium. More importantly, the unique chemical sensitivity of valence-to-core X-ray emission enables us to show that manganese is always coordinated by a CO3-octahedron. This, firstly, provides firm experimental evidence for manganese being primarily located in the inorganic carbonate. Secondly, it indicates that the structure of the aragonitic host is locally altered such that manganese attains an octahedral, calcitic coordination. This modification at the atomic level enables the bivalve to accommodate many orders of magnitude more manganese in its aragonitic shell than found in any non-biogenic aragonite. This outstanding feature is most likely facilitated through the non-classical crystallization pathway of bivalve shells.

  16. Evolution of Microstructures During Austempering of Ductile Irons Alloyed with Manganese and Copper

    NASA Astrophysics Data System (ADS)

    Dasgupta, Ranjan Kumar; Mondal, Dipak Kumar; Chakrabarti, Ajit Kumar

    2013-03-01

    The influences of relatively high manganese (0.45 through 1.0 wt pct) and copper (0.56 through 1.13 wt pct) contents on microstructure development and phase transformation in three austempered ductile irons have been studied. The experimental ductile irons alloyed with copper and manganese are found to be practically free from intercellular manganese segregation. This suggests that the positive segregation of manganese is largely neutralized by the negative segregation of copper when these alloying elements are added in appropriate proportions. The drop in unreacted austenite volume (UAV) with increasing austempering temperature and time is quite significant in irons alloyed with copper and manganese. The ausferrite morphology also undergoes a transition from lenticular to feathery appearance of increasing coarseness with the increasing austempering temperature and time. SEM micrographs of the austempered samples from the base alloy containing manganese only, as well as copper plus manganese-alloyed irons, clearly reveal the presence of some martensite along with retained austenite and ferrite. X-ray diffraction analysis also confirms the presence of these phases. SEM examination further reveals the presence of twinned martensite in the copper plus manganese-alloyed samples. The possibility of strain-induced transformation of austenite to martensite during austempering heat treatment is suggested.

  17. Manganese-56 coincidence-counting facility precisely measures neutron-source strength

    NASA Technical Reports Server (NTRS)

    De Volpi, A.; Larsen, R. N.; Porges, K. G. A.

    1969-01-01

    Precise measurement of neutron-source strength is provided by a manganese 56 coincidence-counting facility using the manganese-bath technique. This facility combines nuclear instrumentation with coincidence-counting techniques to handle a wide variety of radioisotope-counting requirements.

  18. Disease-toxicant screen reveals a neuroprotective interaction between Huntington’s disease and manganese exposure

    PubMed Central

    Williams, B. Blairanne; Li, Daphne; Wegrzynowicz, Michal; Vadodaria, Bhavin K.; Anderson, Joel G.; Kwakye, Gunnar F.; Aschner, Michael; Erikson, Keith M.; Bowman, Aaron B.

    2011-01-01

    Recognizing the similarities between Huntington’s disease pathophysiology and the neurotoxicology of various metals, we hypothesized that they may exhibit disease-toxicant interactions revealing cellular pathways underlying neurodegeneration. Here we utilize metals and the STHdh mouse striatal cell line model of Huntington’s disease to perform a gene-environment interaction screen. We report that striatal cells expressing mutant Huntingtin exhibit elevated sensitivity to cadmium toxicity and resistance to manganese toxicity. This neuroprotective gene-environment interaction with manganese is highly specific, as it does not occur with iron, copper, zinc, cobalt, cadmium, lead, or nickel ions. Analysis of the Akt cell-stress signaling pathway showed diminished activation with manganese exposure and elevated activation after cadmium exposure in the mutant cells. Direct examination of intracellular manganese levels found that mutant cells have a significant impairment in manganese accumulation. Furthermore, YAC128Q mice, a Huntington’s disease model, showed decreased total striatal manganese levels following manganese exposure relative to wild-type mice. Thus, this disease-toxicant interaction screen has revealed that expression of mutant Huntingtin results in heightened sensitivity to cadmium neurotoxicity and a selective impairment of manganese accumulation. PMID:19845833

  19. Synthesis of manganese oxide supported on mesoporous titanium oxide: Influence of the block copolymer

    SciTech Connect

    Schmit, F.; Bois, L.; Chiriac, R.; Toche, F.; Chassagneux, F.; Besson, M.; Descorme, C.; Khrouz, L.

    2015-01-15

    Manganese oxides supported on mesoporous titanium oxides were synthesized via a sol–gel route using block copolymer self-assembly. The oxides were characterized by X-ray diffraction, infrared spectroscopy, thermal analyses, nitrogen adsorption/desorption, electron microscopy and electronic paramagnetic resonance. A mesoporous anatase containing amorphous manganese oxide particles could be obtained with a 0.2 Mn:Ti molar ratio. At higher manganese loading (0.5 Mn:Ti molar ratio), segregation of crystalline manganese oxide occurred. The influence of block copolymer and manganese salt on the oxide structure was discussed. The evolution of the textural and structural characteristics of the materials upon hydrothermal treatment was also investigated. - Graphical abstract: One-pot amorphous MnO{sub 2} supported on mesoporous anataseTiO{sub 2}. - Highlights: • Mesoporous manganese titanium oxides were synthesized using block copolymer. • Block copolymers form complexes with Mn{sup 2+} from MnCl{sub 2}. • With block copolymer, manganese oxide can be dispersed around the titania crystallites. • With Mn(acac){sub 2}, manganese is dispersed inside titania. • MnOOH crystallizes outside mesoporous titania during hydrothermal treatment.

  20. Element substitution by living organisms: the case of manganese in mollusc shell aragonite.

    PubMed

    Soldati, Analia L; Jacob, Dorrit E; Glatzel, Pieter; Swarbrick, Janine C; Geck, Jochen

    2016-01-01

    Determining the manganese concentration in shells of freshwater bivalves provides a unique way to obtain information about climate and environmental changes during time-intervals that pre-date instrumental data records. This approach, however, relies on a thorough understanding of how manganese is incorporated into the shell material -a point that remained controversial so far. Here we clarify this issue, using state-of-the-art X-ray absorption and X-ray emission spectroscopy in combination with band structure calculations. We verify that in the shells of all studied species manganese is incorporated as high-spin Mn(2+), i.e. manganese always has the same valence as calcium. More importantly, the unique chemical sensitivity of valence-to-core X-ray emission enables us to show that manganese is always coordinated by a CO3-octahedron. This, firstly, provides firm experimental evidence for manganese being primarily located in the inorganic carbonate. Secondly, it indicates that the structure of the aragonitic host is locally altered such that manganese attains an octahedral, calcitic coordination. This modification at the atomic level enables the bivalve to accommodate many orders of magnitude more manganese in its aragonitic shell than found in any non-biogenic aragonite. This outstanding feature is most likely facilitated through the non-classical crystallization pathway of bivalve shells. PMID:26957325

  1. Manganese oxide micro-supercapacitors with ultra-high areal capacitance.

    PubMed

    Wang, Xu; Myers, Benjamin D; Yan, Jian; Shekhawat, Gajendra; Dravid, Vinayak; Lee, Pooi See

    2013-05-21

    A symmetric micro-supercapacitor is constructed by electrochemically depositing manganese oxide onto micro-patterned current collectors. High surface-to-volume ratio of manganese oxide and short diffusion distance between electrodes give an ultra-high areal capacitance of 56.3 mF cm(-2) at a current density of 27.2 μA cm(-2). PMID:23563785

  2. Manganese-alumina-ceramic glass eliminates rigid controls necessary in bonding metals to ceramics

    NASA Technical Reports Server (NTRS)

    Hollar, E. L.

    1968-01-01

    Matrix of manganese-alumino-silicate glass simplifies the processes of metallizing alumina ceramics. Because the manganese in the glass is preoxidized to the 2 plus state by firing in nitrogen, the ceramic can be metallized in dry hydrogen. Lengthening the firing time permits a lower metallizing temperature.

  3. Element substitution by living organisms: the case of manganese in mollusc shell aragonite

    PubMed Central

    Soldati, Analia L.; Jacob, Dorrit E.; Glatzel, Pieter; Swarbrick, Janine C.; Geck, Jochen

    2016-01-01

    Determining the manganese concentration in shells of freshwater bivalves provides a unique way to obtain information about climate and environmental changes during time-intervals that pre-date instrumental data records. This approach, however, relies on a thorough understanding of how manganese is incorporated into the shell material –a point that remained controversial so far. Here we clarify this issue, using state-of-the-art X-ray absorption and X-ray emission spectroscopy in combination with band structure calculations. We verify that in the shells of all studied species manganese is incorporated as high-spin Mn2+, i.e. manganese always has the same valence as calcium. More importantly, the unique chemical sensitivity of valence-to-core X-ray emission enables us to show that manganese is always coordinated by a CO3-octahedron. This, firstly, provides firm experimental evidence for manganese being primarily located in the inorganic carbonate. Secondly, it indicates that the structure of the aragonitic host is locally altered such that manganese attains an octahedral, calcitic coordination. This modification at the atomic level enables the bivalve to accommodate many orders of magnitude more manganese in its aragonitic shell than found in any non-biogenic aragonite. This outstanding feature is most likely facilitated through the non-classical crystallization pathway of bivalve shells. PMID:26957325

  4. A new manganese-mediated, cobalt-catalyzed three-component synthesis of (diarylmethyl)sulfonamides

    PubMed Central

    Pignon, Antoine; Martens, Thierry

    2014-01-01

    Summary The synthesis of (diarylmethyl)sulfonamides and related compounds by a new manganese-mediated, cobalt-catalyzed three-component reaction between sulfonamides, carbonyl compounds and organic bromides is described. This organometallic Mannich-like process allows the formation of the coupling products within minutes at room temperature. A possible mechanism, emphasizing the crucial role of manganese is proposed. PMID:24605162

  5. Hot coal gas desulfurization with manganese based sorbents. Quarterly report, June--September 1994

    SciTech Connect

    Hepworth, M.T.; Slimane, R.B.

    1994-11-01

    The focus of work being performed on hot coal gas desulfurization at the Morgantown Energy Technology Center is primarily in the use of zinc titanate sorbents; however, prior studies indicated that an alternate sorbent, manganese dioxide-containing ore in mixture with alumina (75 wt% ore + 25 wt% Al{sub 2}O{sub 3}) appears to be a strong contender to zinc-based sorbents. Manganese, for example, has a lower vapor pressure in the elemental state than zinc; hence, it is not as likely to undergo zinc-depletion from the sorbent surface upon loading and regeneration cycles. Also manganese oxide is less readily reduced to the elemental state than iron; hence, the range of reduction potentials for oxygen is somewhat greater than for zinc ferrite. In addition, thermodynamic analysis of the manganese-oxygen-sulfur system shows it to be less amenable to sulfation than zinc ferrite. Also manganese chlorides are much less stable and volatile than zinc chlorides. Potential also exists for utilization of manganese at higher temperatures than zinc ferrite or zinc titanate. This Eighth Quarterly Report documents progress in pelletizing and testing via thermo-gravimetric analysis of individual pellet formulations of manganese ore/alumina combinations and also manganese carbonate/alumina with two binders, dextrin and bentonite.

  6. 65 FR 34661 - Revocation of Antidumping Duty Orders: Electrolytic Manganese Dioxide From Greece and Japan

    Federal Register 2010, 2011, 2012, 2013, 2014

    2000-05-31

    ...: Electrolytic Manganese Dioxide From Greece, 64 FR 67861(December 3, 1999); and Final Results of Expedited... foreseeable time. (See Electrolytic Manganese Dioxide from Greece and Japan, 65 FR 31348 (May 17, 2000) and... reasonably foreseeable time (65 FR 31348 (May 17, 2000)). Therefore, pursuant to section 751(d)(2) of the...

  7. 68 FR 69987 - Notice of Postponement of Preliminary Antidumping Duty Determinations: Electrolytic Manganese...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2003-12-16

    ... Manganese Dioxide from Australia, Greece, Ireland, Japan, and South Africa, (68 FR 51551, dated August 27... later than January 7, 2004, 140 days after the date of initiation. See 68 FR 51551. The Department is...: Electrolytic Manganese Dioxide from Australia, Greece, Ireland, Japan, and South Africa. AGENCY:...

  8. 64 FR 85 - Electrolytic Manganese Dioxide From Greece: Notice of Extension of Time Limits for Preliminary...

    Federal Register 2010, 2011, 2012, 2013, 2014

    1999-01-04

    ... International Trade Administration Electrolytic Manganese Dioxide From Greece: Notice of Extension of Time... antidumping duty order on electrolytic manganese dioxide from Greece. The period of review is April 1, 1997... Greece. On May 29, 1998, the Department initiated this administrative review covering the period April...

  9. 40 CFR 721.10223 - Styrenyl surface treated manganese ferrite with acrylic ester polymer (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... ferrite with acrylic ester polymer (generic). 721.10223 Section 721.10223 Protection of Environment... manganese ferrite with acrylic ester polymer (generic). (a) Chemical substance and significant new uses... manganese ferrite with acrylic ester polymer (PMN P-09-582) is subject to reporting under this section...

  10. Red-emitting manganese-doped aluminum nitride phosphor

    NASA Astrophysics Data System (ADS)

    Cherepy, Nerine J.; Payne, Stephen A.; Harvey, Nicholas M.; Åberg, Daniel; Seeley, Zachary M.; Holliday, Kiel S.; Tran, Ich C.; Zhou, Fei; Martinez, H. Paul; Demeyer, Jessica M.; Drobshoff, Alexander D.; Srivastava, Alok M.; Camardello, Samuel J.; Comanzo, Holly A.; Schlagel, Deborah L.; Lograsso, Thomas A.

    2016-04-01

    We report high efficiency luminescence with a manganese-doped aluminum nitride red-emitting phosphor under 254 nm excitation, as well as its excellent lumen maintenance in fluorescent lamp conditions, making it a candidate replacement for the widely deployed europium-doped yttria red phosphor. Solid-state reaction of aluminum nitride powders with manganese metal at 1900 °C, 10 atm N2 in a reducing environment results in nitrogen deficiency, as revealed diffuse reflectance spectra. When these powders are subsequently annealed in flowing nitrogen at 1650 °C, higher nitrogen content is recovered, resulting in white powders. Silicon was added to samples as an oxygen getter to improve emission efficiency. NEXAFS spectra and DFT calculations indicate that the Mn dopant is divalent. From DFT calculations, the UV absorption band is proposed to be due to an aluminum vacancy coupled with oxygen impurity dopants, and Mn2+ is assumed to be closely associated with this site. In contrast with some previous reports, we find that the highest quantum efficiency with 254 nm excitation (Q.E. = 0.86 ± 0.14) is obtained in aluminum nitride with a low manganese doping level of 0.06 mol.%. The principal Mn2+ decay of 1.25 ms is assigned to non-interacting Mn sites, while additional components in the microsecond range appear with higher Mn doping, consistent with Mn clustering and resultant exchange coupling. Slower components are present in samples with low Mn doping, as well as strong afterglow, assigned to trapping on shallow traps followed by detrapping and subsequent trapping on Mn.

  11. Red-emitting manganese-doped aluminum nitride phosphor

    DOE PAGESBeta

    Cherepy, Nerine J.; Payne, Stephen A.; Harvey, Nicholas M.; Aberg, Daniel; Seeley, Zachary M.; Holliday, Kiel S.; Tran, Ich C.; Zhou, Fei; Martinez, H. Paul; Demeyer, Jessica M.; et al

    2016-02-10

    Here, we report high efficiency luminescence with a manganese-doped aluminum nitride red-emitting phosphor under 254 nm excitation, as well as its excellent lumen maintenance in fluorescent lamp conditions, making it a candidate replacement for the widely deployed europium-doped yttria red phosphor. Solid-state reaction of aluminum nitride powders with manganese metal at 1900 °C, 10 atm N2 in a reducing environment results in nitrogen deficiency, as revealed diffuse reflectance spectra. When these powders are subsequently annealed in flowing nitrogen at 1650 °C, higher nitrogen content is recovered, resulting in white powders. Silicon was added to samples as an oxygen getter tomore » improve emission efficiency. NEXAFS spectra and DFT calculations indicate that the Mn dopant is divalent. From DFT calculations, the UV absorption band is proposed to be due to an aluminum vacancy coupled with oxygen impurity dopants, and Mn2+ is assumed to be closely associated with this site. In contrast with some previous reports, we find that the highest quantum efficiency with 254 nm excitation (Q.E. = 0.86 ± 0.14) is obtained in aluminum nitride with a low manganese doping level of 0.06 mol.%. The principal Mn2+ decay of 1.25 ms is assigned to non-interacting Mn sites, while additional components in the microsecond range appear with higher Mn doping, consistent with Mn clustering and resultant exchange coupling. Slower components are present in samples with low Mn doping, as well as strong afterglow, assigned to trapping on shallow traps followed by detrapping and subsequent trapping on Mn.« less

  12. Tensile behavior of irradiated manganese-stabilized stainless steel

    SciTech Connect

    Klueh, R.L.

    1996-10-01

    Tensile tests were conducted on seven experimental, high-manganese austenitic stainless steels after irradiation up to 44 dpa in the FFTF. An Fe-20Mn-12Cr-0.25C base composition was used, to which various combinations of Ti, W, V, B, and P were added to improve strength. Nominal amounts added were 0.1% Ti, 1% W, 0.1% V, 0.005% B, and 0.03% P. Irradiation was carried out at 420, 520, and 600{degrees}C on the steels in the solution-annealed and 20% cold-worked conditions. Tensile tests were conducted at the irradiation temperature. Results were compared with type 316 SS. Neutron irradiation hardened all of the solution-annealed steels at 420, 520, and 600{degrees}C, as measured by the increase in yield stress and ultimate tensile strength. The steel to which all five elements were added to the base composition showed the least amount of hardening. It also showed a smaller loss of ductility (uniform and total elongation) than the other steels. The total and uniform elongations of this steel after irradiation at 420{degrees}C was over four times that of the other manganese-stabilized steels and 316 SS. There was much less difference in strength and ductility at the two higher irradiation temperatures, where there was considerably less hardening, and thus, less loss of ductility. In the cold-worked condition, hardening occured only after irradiation at 420{degrees}C, and there was much less difference in the properties of the steels after irradiation. At the 420{degrees}C irradiation temperature, most of the manganese-stabilized steels maintained more ductility than the 316 SS. After irradiation at 420{degrees}C, the temperature of maximum hardening, the steel to which all five of the elements were added had the best uniform elongation.

  13. Manganese-Based Molecular Electrocatalysts for Oxidation of Hydrogen

    SciTech Connect

    Hulley, Elliott; Kumar, Neeraj; Raugei, Simone; Bullock, R. Morris

    2015-10-05

    Oxidation of H2 (1 atm) is catalyzed by the manganese electrocatalysts [(P2N2)MnI(CO)(bppm)]+ and [(PNP)MnI(CO)(bppm)]+ (P2N2= 1,5-dibenzyl-3,7-diphenyl-1,5-diaza-3,7-diphosphacyclooctane; PNP = (Ph2PCH2)2NMe); bppm = (PArF2)2CH2, and ArF = 3,5-(CF3)2C6H3). In fluorobenzene solvent using 2,6-lutidine as the exogeneous base, the turnover frequency for [(P2N2)MnI(CO)(bppm)]+ is 3.5 s-1 with an estimated overpotential of 590 mV. For [(PNP)MnI(CO)(bppm)], in fluorobenzene solvent using N-methylpyrrolidine as the exogeneous base, the turnover frequency is 1.4 s-1 with an estimated overpotential of 700 mV. Density functional theory calculations suggest that the slow step in the catalytic cycle is proton transfer from the oxidized 17-electron manganese hydride, e.g., [(P2N2)MnIIH(CO)(bppm)]+ to the pendant amine. The computed activation barrier for intramolecular proton transfer from the metal to the pendant amine is 20.4 kcal/mol in [(P2N2)MnIIH(CO)(bppm)]+ and 21.3 kcal/mol in [(PNP)MnI(CO)(bppm)]. The high barrier appears to result from both the unfavorability of metal-to-nitrogen proton transfer (thermodynamically uphill by 6.6 pKa units, 9 kcal/mol), as well as the relatively long manganese-nitrogen separation in the MnIIH complexes.

  14. Manganese-Enhanced Magnetic Resonance Imaging of Traumatic Brain Injury

    PubMed Central

    Talley Watts, Lora; Shen, Qiang; Deng, Shengwen; Chemello, Jonathan

    2015-01-01

    Abstract Calcium dysfunction is involved in secondary traumatic brain injury (TBI). Manganese-enhanced MRI (MEMRI), in which the manganese ion acts as a calcium analog and a MRI contrast agent, was used to study rats subjected to a controlled cortical impact. Comparisons were made with conventional T2 MRI, sensorimotor behavior, and immunohistology. The major findings were: (1) Low-dose manganese (29 mg/kg) yielded excellent contrast with no negative effects on behavior scores relative to vehicle; (2) T1-weighted MEMRI was hyperintense in the impact area at 1–3 h, hypointense on day 2, and markedly hypointense with a hyperintense area surrounding the core on days 7 and/or 14, in contrast to the vehicle group, which did not show a biphasic profile; (3) in the hyperacute phase, the area of hyperintense T1-weighted MEMRI was larger than that of T2 MRI; (4) glial fibrillary acidic protein staining revealed that the MEMRI signal void in the impact core and the hyperintense area surrounding the core on day 7 and/or 14 corresponded to tissue cavitation and reactive gliosis, respectively; (5) T2 MRI showed little contrast in the impact core at 2 h, hyperintense on day 2 (indicative of vasogenic edema), hyperintense in some animals but pseudonormalized in others on day 7 and/or 14; (6) behavioral deficit peaked on day 2. We concluded that MEMRI detected early excitotoxic injury in the hyperacute phase, preceding vasogenic edema. In the subacute phase, MEMRI detected contrast consistent with tissue cavitation and reactive gliosis. MEMRI offers novel contrasts of biological processes that complement conventional MRI in TBI. PMID:25531419

  15. High-frequency electromagnetic properties of the manganese ferrite nanoparticles

    NASA Astrophysics Data System (ADS)

    Zeng, Min; Liu, Jue; Yue, Ming; Yang, Haozhe; Dong, Hangrong; Tang, Wukui; Jiang, He; Liu, Xiaofang; Yu, Ronghai

    2015-05-01

    Manganese (MnFe2O4) nanoparticles are prepared via a facile solvothermal method. The electromagnetic properties are investigated in 1-18 GHz, indicating the MnFe2O4 nanoparticles are the promising materials to be applied as microwave absorbers. The wave absorbing mechanism can be attributed to the dielectric loss, magnetic loss, and the synergetic effect. The permittivity dispersion behavior is explained by Debye dipolar relation expression. The complex permeability is analyzed using Landau-Lifshitz-Gilbert equation. Natural resonance, exchange resonance, and eddy current loss arise at different frequencies.

  16. Kα X-ray emission in manganese compounds

    NASA Astrophysics Data System (ADS)

    Jabua, Malkhaz; Gotta, Detlev; Strauch, Thomas; Weidemann, Christian; Fricke, Burkhard; Rashid, Khalid

    2016-07-01

    Kα X-ray emission spectra of manganese compounds have been measured using an ultimate-resolution Bragg spectrometer optimised for long-term high-statistics measurements. Energies corresponding to the peak positions of the Kα lines were measured to a precision of 10-20 meV. Total line widths of the Kα1 and Kα2 components and their asymmetry have been determined to about 50 meV. A model-free parametrisation of the line pattern corrected for the spectrometer response may serve as testing ground for detailed theoretical considerations.

  17. Structural and mechanical studies of cadmium manganese thiocyanate crystal

    NASA Astrophysics Data System (ADS)

    Manikandan, M. R.; Vijayaprasath, G.; babu, G. Anandha; Bhagavannarayan, G.; Vijayan, N.; Ravi, G.

    2012-06-01

    Single crystals of cadmium manganese thiocyanate (CMTC) have been synthesized successfully and grown by slow evaporation method. The structural perfection of the grown crystals has been analyzed by High resolution X-ray diffraction (HRXRD), which shows the crystalline perfection of the grown crystal is quite good. Optical behavior was assessed by UV-Vis analysis and found that no absorption in the UV visible region and it may be useful for second harmonic applications. The mechanical hardness of the grown crystals was studied and Vicker's microhardness, Stiffness constant was calculated.

  18. Recent synthetic applications of manganese in organic synthesis.

    PubMed

    Concellón, José M; Rodríguez-Solla, Humberto; Del Amo, Vicente

    2008-01-01

    While the organometallic compounds derived from many metals have found a broad application in organic synthesis, the use of organomanganese compounds has only recently been developed due to the passivity exhibited by commercial Mn in the direct metalation of organic compounds. In this Concept article, we highlight the potential of manganese and its organometallic compounds in organic synthesis by illustration of the studies previously reported by others and our laboratory in this field. Based on the transformations reported herein, organomanganese compounds could become important tools in the future of the organic synthesis, due to their high selectivity. PMID:18752228

  19. Sorption J-T refrigeration utilizing manganese nitride chemisorption

    NASA Technical Reports Server (NTRS)

    Jones, Jack; Lund, Alan

    1990-01-01

    The equilibrium pressures and compositions have been measured for a system of finely powdered manganese nitride and nitrogen gas at 650, 700, 800, and 850 C for various nitrogen loadings. Pressures ranged from less than 0.02 MPa at 650 C to 6.38 MPa at 850 C. Analysis of the test results has shown that under certain conditions Mn(x)N(y) could potentially be used in a triple regenerative sorption compressor refrigeration system, but the potential power savings are small compared to the increased complexity and reliability problems associated with very high temperature (above 950 C) pressurized systems.

  20. Magmatogenic manganese ores of the South Minusa Intermontane Trough

    NASA Astrophysics Data System (ADS)

    Kassandrov, E. G.; Mazurov, M. P.

    2009-10-01

    The first data on the mineral composition and formation conditions of manganese ore at the Chapsordag and Malosyrsky deposits in the Askiz ore district of Khakassia are integrated and systematized. The detailed mineralogical mapping of the deposits has been carried out. The identification of minerals and examination of the ore microstructure were performed with optical microscopy in transmitted and reflected light and using SEM/EDS, EMPA, XRD, IRS, and other methods. It was established that the ore mineralization is spatially and genetically related to the Early Devonian magmatism and accompanying hydrothermal activity and metasomatism. Syngenetic braunite was detected for the first time in elevated amounts reaching an economic level in the devitrified groundmass of volcanic rocks, in cement of lava breccia, and in fragments in pyroclastic rocks. By analogy with iron deposits, this magmatogenic type of manganese mineralization is regarded as ore lavas and tuffs combined with metasomatic and hydrothermal mineral assemblages into a strata-bound orebearing complex and as a source of hydrothermal metasomatic ore. The elevated Mn content in magmatic melts of the Early Devonian trachybasalt-trachyandesite-trachydacite association is caused by assimilation of Riphean and Lower Cambrian high-Mn carbonate sequences in crustal magma chambers. In contours of economic orebodies, the hydrothermal economic ore is recognized as sites of massive, patchy and impregnated, brecciated, stringer-disseminated, and disseminated varieties. High-grade massive ore occurs as stratiform and branching bodies up to 1.5 m thick and a few tens of meters long and as smaller pocketlike bodies. Braunite and pyrolusite (polianite) are major ore minerals varying in size, degree of crystallinity, and character of intergrowths with associating minerals. Gangue minerals include carbonates, sulfates, albite, quartz, chlorite, actinolite, piemontite, and okhotskite, a Mn-pumpellyite identified in Russia

  1. Electronic and magnetic properties of manganese impurities in aluminum

    NASA Astrophysics Data System (ADS)

    Bagayoko, D.; Brener, N.; Kanhere, D.; Callaway, J.

    1987-12-01

    We studied the electronic structure of manganese impurities in a fcc aluminum matrix by means of calculations for a free MnAl18 cluster. Our ab initio self-consistent computations employed the Rajagopal-Singhal-Kimball local-spin-density potential and a symmetrized Gaussian-orbital basis. The local and cluster magnetic moments are, respectively, 1.74μB and 1.0μB. Substantial screening of the Mn moment by opposite polarization of the surrounding Al atoms was found.

  2. Manganese ion-assisted assembly of superparamagnetic graphene oxide microbowls

    SciTech Connect

    Tian, Zhengshan; Xu, Chunxiang Li, Jitao; Zhu, Gangyi; Xu, Xiaoyong; Dai, Jun; Shi, Zengliang; Lin, Yi

    2014-03-24

    A facile manganese ion Mn(II)-assisted assembly has been designed to fabricate microbowls by using graphene oxide nanosheets as basic building blocks, which were exfoliated ultrasonically from the oxidized soot powders in deionized water. From the morphology evolution observations of transmission electron microscope and scanning electron microscope, a coordinating-tiling-collapsing manner is proposed to interpret the assembly mechanism based on attractive Van der Waals forces, π-π stacking, and capillary action. It is interesting to note that the as-prepared microbowls present a room temperature superparamagnetic behavior.

  3. Synthesis of manganese oxide supported on mesoporous titanium oxide: Influence of the block copolymer

    NASA Astrophysics Data System (ADS)

    Schmit, F.; Bois, L.; Chiriac, R.; Toche, F.; Chassagneux, F.; Besson, M.; Descorme, C.; Khrouz, L.

    2015-01-01

    Manganese oxides supported on mesoporous titanium oxides were synthesized via a sol-gel route using block copolymer self-assembly. The oxides were characterized by X-ray diffraction, infrared spectroscopy, thermal analyses, nitrogen adsorption/desorption, electron microscopy and electronic paramagnetic resonance. A mesoporous anatase containing amorphous manganese oxide particles could be obtained with a 0.2 Mn:Ti molar ratio. At higher manganese loading (0.5 Mn:Ti molar ratio), segregation of crystalline manganese oxide occurred. The influence of block copolymer and manganese salt on the oxide structure was discussed. The evolution of the textural and structural characteristics of the materials upon hydrothermal treatment was also investigated.

  4. Psychological test performance in foundry workers exposed to low levels of manganese

    SciTech Connect

    Iregren, A. )

    1990-11-01

    A sample of 30 manganese-exposed foundry workers from two Swedish plants were examined with a partly computerized psychological test battery, comprised of 10 performance tests. Performance of the manganese-exposed workers was compared to that of a matched control group of 60 workers. Matching criteria were age, geographical area, type of work, and the results on a test of verbal comprehension. Performance of the exposed workers was inferior to that of the control group on tests of simple reaction time, digit span, and finger tapping. No correlations were found between performance and the present manganese exposure levels or the number of years employed in manganese work. The results seem to indicate that the present exposure standards for manganese, in Sweden 2.5 mg/m3 and in most other countries 5 mg/m3, are not sufficient to protect workers from negative effects on performance capacity.

  5. Development of optically transparent water oxidation catalysts using manganese pyrophosphate compounds.

    PubMed

    Takashima, Toshihiro; Hotori, Yuki; Irie, Hiroshi

    2015-11-01

    One challenge in artificial photosynthetic systems is the development of active oxygen evolution catalysts composed of abundant elements. The oxygen evolution activities of manganese pyrophosphate compounds were examined in electrochemical and photochemical experiments. Electrocatalysis using calcium-manganese pyrophosphate exhibited good catalytic ability under neutral pH and an oxygen evolution reaction was driven with a small overpotential (η<100 mV). UV-vis diffuse reflectance measurements revealed that manganese pyrophosphates exhibit weak absorption in the visible light region while commonly used oxygen evolution catalysts exhibit intense absorption. Therefore, the efficient light absorption of a photocatalyst was retained even after surface modification with a manganese pyrophosphate, and photochemical oxygen evolution was achieved by using magnesium ferrite modified with manganese pyrophosphate nanoparticles under the illumination of visible light at wavelength of over 420 nm. PMID:25648929

  6. Effect of Manganese on some aspects of carbohydrate metabolism in rats. [None

    SciTech Connect

    Husain, R.; Mushtaq, M.; Seth, P.K.

    1980-10-01

    Numerous biochemical and toxicological studies have indicated that chronic exposure to manganese leads to neurological abnormalities. Increasing use of manganese compounds as antiknocks in gasoline and diesel fuel has aroused a great concern over the toxicological potential of this metal and stressed the need for understanding the mechanism of its poisoning. Reports of alerations in the levels of biogenic amines have helped in understanding the basis of neurological disorders. However, little is known about the mechanism by which manganese exposure leads to hypoglycemia in workers. This study deals with the influence of manganese exposure on metabolism of glucose, the chief fuel of the brain, and some enzymes involved in its oxidation. These studies will provide an assessment of the extent to which manganese affects the various processes controlling carbohydrate metabolism.

  7. Energetic basis of catalytic activity of layered nanophase calcium manganese oxides for water oxidation

    PubMed Central

    Birkner, Nancy; Nayeri, Sara; Pashaei, Babak; Najafpour, Mohammad Mahdi; Casey, William H.; Navrotsky, Alexandra

    2013-01-01

    Previous measurements show that calcium manganese oxide nanoparticles are better water oxidation catalysts than binary manganese oxides (Mn3O4, Mn2O3, and MnO2). The probable reasons for such enhancement involve a combination of factors: The calcium manganese oxide materials have a layered structure with considerable thermodynamic stability and a high surface area, their low surface energy suggests relatively loose binding of H2O on the internal and external surfaces, and they possess mixed-valent manganese with internal oxidation enthalpy independent of the Mn3+/Mn4+ ratio and much smaller in magnitude than the Mn2O3-MnO2 couple. These factors enhance catalytic ability by providing easy access for solutes and water to active sites and facile electron transfer between manganese in different oxidation states. PMID:23667149

  8. Preparation and characterization of amorphous manganese sulfide thin films by SILAR method

    SciTech Connect

    Pathan, H.M.; Kale, S.S.; Lokhande, C.D.; Han, Sung-Hwan . E-mail: shhan@hanyang.ac.kr; Joo, Oh-Shim

    2007-08-07

    Manganese sulfide thin films were deposited by a simple and inexpensive successive ionic layer adsorption and reaction (SILAR) method using manganese acetate as a manganese and sodium sulfide as sulfide ion sources, respectively. Manganese sulfide films were characterized for their structural, surface morphological and optical properties by means of X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis and optical absorption measurement techniques. The as-deposited film on glass substrate was amorphous. The optical band gap of the film was found to be thickness dependent. As thickness increases optical band gap was found to be increase. The water angle contact was found to be 34{sup o}, suggesting hydrophilic nature of manganese sulfide thin films. The presence of Mn and S in thin film was confirmed by energy dispersive X-ray analysis.

  9. Does manganese protect cultured human skin fibroblasts against oxidative injury by UVA, dithranol and hydrogen peroxide?

    PubMed

    Parat, M O; Richard, M J; Leccia, M T; Amblard, P; Favier, A; Beani, J C

    1995-10-01

    Reactive oxygen species (ROS) are involved in the mechanism of photoaging and carcinogenesis. Skin is endowed with antioxidant enzymes including superoxide dismutases (SOD): cytosolic copper zinc SOD and mitochondrial manganese SOD. The aim of our study was to estimate the protective effect of manganese against oxidative injury on cultured human skin fibroblasts. Dithranol, hydrogen peroxide and UV-A radiation (375 nm) were employed as oxidative stressors. The supply of manganese chloride produced an increase in cellular content of this element up to 24 fold without concomitant elevation of MnSOD activity. Nevertheless, manganese protects cells against two of the three ROS generating systems assessed, namely hydrogen peroxyde and UV-A. This protective effect depends on the concentration of manganese in the medium, 0.1 mM and 0.2 mM protect against UVA cytotoxicity, only 0.2 mM protects against H2O2 cytotoxicity. PMID:7493040

  10. Extracellular zinc competitively inhibits manganese uptake and compromises oxidative stress management in Streptococcus pneumoniae.

    PubMed

    Eijkelkamp, Bart A; Morey, Jacqueline R; Ween, Miranda P; Ong, Cheryl-lynn Y; McEwan, Alastair G; Paton, James C; McDevitt, Christopher A

    2014-01-01

    Streptococcus pneumoniae requires manganese for colonization of the human host, but the underlying molecular basis for this requirement has not been elucidated. Recently, it was shown that zinc could compromise manganese uptake and that zinc levels increased during infection by S. pneumoniae in all the niches that it colonized. Here we show, by quantitative means, that extracellular zinc acts in a dose dependent manner to competitively inhibit manganese uptake by S. pneumoniae, with an EC50 of 30.2 µM for zinc in cation-defined media. By exploiting the ability to directly manipulate S. pneumoniae accumulation of manganese, we analyzed the connection between manganese and superoxide dismutase (SodA), a primary source of protection for S. pneumoniae against oxidative stress. We show that manganese starvation led to a decrease in sodA transcription indicating that expression of sodA was regulated through an unknown manganese responsive pathway. Intriguingly, examination of recombinant SodA revealed that the enzyme was potentially a cambialistic superoxide dismutase with an iron/manganese cofactor. SodA was also shown to provide the majority of protection against oxidative stress as a S. pneumoniae ΔsodA mutant strain was found to be hypersensitive to oxidative stress, despite having wild-type manganese levels, indicating that the metal ion alone was not sufficiently protective. Collectively, these results provide a quantitative assessment of the competitive effect of zinc upon manganese uptake and provide a molecular basis for how extracellular zinc exerts a 'toxic' effect on bacterial pathogens, such as S. pneumoniae. PMID:24558498

  11. Responses of Pisum sativum L. to exogenous indole acetic acid application under manganese toxicity.

    PubMed

    Gangwar, Savita; Singh, Vijay Pratap; Maurya, Jagat Narayan

    2011-06-01

    Responses of pea (Pisum sativum L.) seedlings to manganese (50, 100 and 250 μM) and indole acetic acid (10 and 100 μM) treatments were investigated. Single and combined exposure of pea to manganese and 100 μM indole acetic acid decreased root and shoot fresh mass, chlorophyll, carotenoids, protein and nitrogen while ammonium content increased compared to the control. Combined treatment of pea with 250 μM manganese and 100 μM indole acetic acid decreased root and shoot fresh mass by 54% and 51%, chlorophyll and carotenoids by 31% and 26%, root and shoot protein by 47% and 44%, and root and shoot nitrogen by 44% and 40%, respectively. Activities of glutamine synthetase and glutamate synthase were decreased by the exposure of manganese and 100 μM indole acetic acid while glutamate dehydrogenase activity increased. Combined application of 250 μM manganese and 100 μM indole acetic acid decreased root and shoot glutamine synthetase activity by 44% and 39%, and glutamate synthase activity by 39% and 37% while root and shoot glutamate dehydrogenase activity increased by 47% and 42%, respectively compared to the control. In contrast, application of 10 μM indole acetic acid together with manganese decreased the negative impacts of manganese, and promoted seedling growth compared to the manganese treatments alone. This study has shown that 10 μM indole acetic acid protected pea seedlings appreciably from manganese toxicity by regulating ammonium content and the activities of enzymes of ammonium assimilation, while 100 μM of indole acetic acid exhibited opposite response under manganese toxicity. PMID:21516457

  12. Manganese supplementation protects against diet-induced diabetes in wild type mice by enhancing insulin secretion.

    PubMed

    Lee, Soh-Hyun; Jouihan, Hani A; Cooksey, Robert C; Jones, Deborah; Kim, Hyung J; Winge, Dennis R; McClain, Donald A

    2013-03-01

    Mitochondrial dysfunction is both a contributing mechanism and complication of diabetes, and oxidative stress contributes to that dysfunction. Mitochondrial manganese-superoxide dismutase (MnSOD) is a metalloenzyme that provides antioxidant protection. We have previously shown in a mouse model of hereditary iron overload that cytosolic iron levels affected mitochondrial manganese availability, MnSOD activity, and insulin secretion. We therefore sought to determine the metallation status of MnSOD in wild-type mice and whether altering that status affected β-cell function. 129/SvEVTac mice given supplemental manganese exhibited a 73% increase in hepatic MnSOD activity and increased metallation of MnSOD. To determine whether manganese supplementation offered glucose homeostasis under a situation of β-cell stress, we challenged C57BL/6J mice, which are more susceptible to diet-induced diabetes, with a high-fat diet for 12 weeks. Manganese was supplemented or not for the final 8 weeks on that diet, after which we examined glucose tolerance and the function of isolated islets. Liver mitochondria from manganese-injected C57BL/6J mice had similar increases in MnSOD activity (81%) and metallation as were seen in 129/SvEVTac mice. The manganese-treated group fed high fat had improved glucose tolerance (24% decrease in fasting glucose and 41% decrease in area under the glucose curve), comparable with mice on normal chow and increased serum insulin levels. Isolated islets from the manganese-treated group exhibited improved insulin secretion, decreased lipid peroxidation, and improved mitochondrial function. In conclusion, MnSOD metallation and activity can be augmented with manganese supplementation in normal mice on normal chow, and manganese treatment can increase insulin secretion to improve glucose tolerance under conditions of dietary stress. PMID:23372018

  13. A X-Ray Absorption Spectroscopy Study of Manganese Containing Compounds and Photosynthetic Spinach Chloroplasts.

    NASA Astrophysics Data System (ADS)

    Kirby, Jon Allan

    The manganese sites in chloroplasts, long thought to be involved in photosynthetic oxygen evolution have been examined and partially characterized by X-ray Absorption Spectroscopy (XAS) using synchrotron radiation. The local environment about the manganese atoms is estimated from an analysis of the extended X-ray Absorption Fine Structure (EXAFS). Comparisons with and simulations of the manganese EXAFS for several reference compounds leads to a model in which the chloroplast manganese atoms are contained in a binuclear complex similar to di-u-oxo -tetrakis-(2,2'-bipyridine) dimanganese. It is suggested that the partner metal is another manganese. The bridging ligands are most probably oxygen. The remaining manganese ligands are carbon, oxygen, or nitrogen. A roughly linear correlation between the X-ray K edge onset energy and the "coordination charge" of a large number of manganese coordination complexes and compounds has been developed. Entry of the chloroplast manganese edge energy onto this correlation diagram establishes that the active pool of manganese is in an oxidation state greater than +2. If the manganese is in a dimeric form the oxidation states are most probably (II,III). Underlying these results is an extensive data analysis methodology. The method developed involves the use of many different background removal techniques, Fourier transforms and ultimately curve fitting to the modulations in the x-ray absorption cross sections. A large number of model compounds were used to evaluate the analysis method. These analyses are used to show that the two major curve fitting models available are essentially equivalent. Due to its greater versatility, the theoretical model of Teo and Lee is preferred (J. Am. Chem. Soc. (1979), 101, 2815). The results are also used to determine the informational limitations of XAS within the limits of the present understanding of X-ray absorption phenomena by inner shell electrons for atoms with atomic number greater than that

  14. Extracellular Zinc Competitively Inhibits Manganese Uptake and Compromises Oxidative Stress Management in Streptococcus pneumoniae

    PubMed Central

    Eijkelkamp, Bart A.; Morey, Jacqueline R.; Ween, Miranda P.; Ong, Cheryl-lynn Y.; McEwan, Alastair G.; Paton, James C.; McDevitt, Christopher A.

    2014-01-01

    Streptococcus pneumoniae requires manganese for colonization of the human host, but the underlying molecular basis for this requirement has not been elucidated. Recently, it was shown that zinc could compromise manganese uptake and that zinc levels increased during infection by S. pneumoniae in all the niches that it colonized. Here we show, by quantitative means, that extracellular zinc acts in a dose dependent manner to competitively inhibit manganese uptake by S. pneumoniae, with an EC50 of 30.2 µM for zinc in cation-defined media. By exploiting the ability to directly manipulate S. pneumoniae accumulation of manganese, we analyzed the connection between manganese and superoxide dismutase (SodA), a primary source of protection for S. pneumoniae against oxidative stress. We show that manganese starvation led to a decrease in sodA transcription indicating that expression of sodA was regulated through an unknown manganese responsive pathway. Intriguingly, examination of recombinant SodA revealed that the enzyme was potentially a cambialistic superoxide dismutase with an iron/manganese cofactor. SodA was also shown to provide the majority of protection against oxidative stress as a S. pneumoniae ΔsodA mutant strain was found to be hypersensitive to oxidative stress, despite having wild-type manganese levels, indicating that the metal ion alone was not sufficiently protective. Collectively, these results provide a quantitative assessment of the competitive effect of zinc upon manganese uptake and provide a molecular basis for how extracellular zinc exerts a ‘toxic’ effect on bacterial pathogens, such as S. pneumoniae. PMID:24558498

  15. Bioaccumulation of manganese and its toxicity in feral pigeons (Columba livia) exposed to manganese oxide dust (Mn{sub 3}O{sub 4})

    SciTech Connect

    Sierra, P.; Chakrabarti, S.; Tounkara, R.; Loranger, S.; Kennedy, G.; Zayed, J.

    1998-11-01

    Manganese tetroxide (Mn{sub 3}O{sub 4}) is a product from the combustion of methylcyclopentadienyl manganese tricarbonyl. Exposure to high levels of manganese can lead to serious health effects especially to the central nervous and respiratory systems. Very few studies on the effects of long-term low level exposure to Mn{sub 3}O{sub 4} have been reported. The present study was therefore conducted to examine the bioaccumulation and toxicity of manganese in various organs of feral pigeons (Columba kivia) when exposed to low levels of Mn{sub 3}O{sub 4} via inhalation and hence to find any possible relationship between these two parameters. A total of 22 pigeons was exposed to 239 {micro}g/m{sup 3} of manganese for 7 h/day, 5 days/week for 5, 9, and 13 consecutive weeks. Manganese concentrations in various tissues, e.g., brain (mesencephalon), lung, liver, intestine, pancreas, kidney, muscle, bone, and whole blood, were measured by neutron activation analysis. Various biochemical parameters in blood, e.g., hematocrit, total proteins, glucose, uric acid, alinine aminotransferase, total iron, blood urea nitrogen and triglycerides, were also measured.

  16. Pharmacokinetic Evaluation of the Equivalency of Gavage, Dietary, and Drinking Water Exposure to Manganese in F344 Rats

    PubMed Central

    Foster, Melanie L.; Bartnikas, Thomas B.; Johnson, Laura C.; Herrera, Carolina; Pettiglio, Michael A.; Keene, Athena M.; Taylor, Michael D.; Dorman, David C.

    2015-01-01

    Concerns exist as to whether individuals may be at greater risk for neurotoxicity following increased manganese (Mn) oral intake. The goals of this study were to determine the equivalence of 3 methods of oral exposure and the rate (mg Mn/kg/day) of exposure. Adult male rats were allocated to control diet (10 ppm), high manganese diet (200 ppm), manganese-supplemented drinking water, and manganese gavage treatment groups. Animals in the drinking water and gavage groups were given the 10 ppm manganese diet and supplemented with manganese chloride (MnCl2) in drinking water or once-daily gavage to provide a daily manganese intake equivalent to that seen in the high-manganese diet group. No statistically significant difference in body weight gain or terminal body weights was seen. Rats were anesthetized following 7 and 61 exposure days, and samples of bile and blood were collected. Rats were then euthanized and striatum, olfactory bulb, frontal cortex, cerebellum, liver, spleen, and femur samples were collected for chemical analysis. Hematocrit was unaffected by manganese exposure. Liver and bile manganese concentrations were elevated in all treatment groups on day 61 (relative to controls). Increased cerebellum manganese concentrations were seen in animals from the high-manganese diet group (day 61, relative to controls). Increased (relative to all treatment groups) femur, striatum, cerebellum, frontal cortex, and olfactory bulb manganese concentrations were also seen following gavage suggesting that dose rate is an important factor in the pharmacokinetics of oral manganese. These data will be used to refine physiologically based pharmacokinetic models, extending their utility for manganese risk assessment by including multiple dietary exposures. PMID:25724921

  17. Characterization of Manganese-doped Willemite Green Phosphor Gel Powders

    NASA Astrophysics Data System (ADS)

    Tsai, Mu-Tsun; Lin, Yi-Hsun; Yang, Jing-Ru

    2011-10-01

    Nanocrystalline manganese-doped zinc silicate (Zn2-xMnxSiO4 x = 0-12.0 mol%) powder phosphors were prepared by the sol-gel process. Zinc chloride, tetraethylorthosilicate, and manganese chloride were employed as precursors. The influences of water concentration on the crystallization and photoluminescence of the phosphors were investigated. Single-phase wiemite (α-Zn2SiO4) started to crystallize after calcining at 600°C for powders derived from low-water-conen so, whie β-Zn2SiO4 became the dominated phase with residual ZnO trace for high-water-content sol derived powders as calcining at below 900 °C. On firing at 800°-1200°C, the resulting phosphors had the average crystallite sizes of 15~38 nm. With various content of water and heating the powders at 800°C, the prepared phosphors exhibited yellow and green emission peaking at 556 and 524 nm, respectively. Upon heating at 1200 °C, powder phosphors exhibited prominent photoluminescence emission bands peaked at 522~526 nm, depending on the doping content. The luminous efficiency has been investigated as a function of dopant content and heating temperature.

  18. Solution synthesis and characterization of lithium manganese oxide cathode materials

    SciTech Connect

    Voigt, J.A.; Boyle, T.J.; Doughty, D.H.

    1995-07-01

    A nonaqueous coprecipitation process has been developed to prepare controlled stoichiometry lithium manganese oxalate precipitates. The process involved mixing a methanolic Li-Mn nitrate solution with a methanolic solution containing tetramethylammonium oxalate as the precipitating agent. The resulting oxalates were readily converted to a variety of phase pure lithium manganese oxides at moderate temperatures ({le}600{degrees}C), where the phase formed was determined by the initial Li/Mn ratio in the starting solution. Metal cation dopants have been incorporated into the oxalate precipitate by dissolving the appropriate metal nitrate in the Li-Mn precursor solution The various starting solutions, oxalate precipitates, and calcined oxides have been extensively characterized using a variety of techniques, including {sup 7}Li NMR, TGA/DTA, SEM, and XRD. Results indicate that a strong interaction occurs between Li and Mn in the nitrate solution which carries over into the oxalate phase during precipitation. The morphology and the crystallite size of the oxide powders were shown to be controlled by the morphology of the oxalate precursor and the oxalate calcination temperature, respectively. The results of initial cathode performance tests with respect to dopant type (Al, Ni, Co) and concentration for LiMn{sub 2}O{sub 4} are also reported.

  19. Raman Microscopy of Lithium-Manganese-Rich Cathodes

    DOE PAGESBeta

    Ruther, Rose E; Callender, Andrew F.; Zhou, Hui; Martha, Surendra; Nanda, Jagjit

    2014-01-01

    Lithium rich, manganese rich composites with general formula xLi2MnO3 (1-x)LiMO2 are promising candidates for high capacity and high voltage cathodes for lithium ion batteries. Lithium rich oxides crystallize as a nanocomposite of layered phases whose structure further evolves with electrochemical cycling. Raman spectroscopy is potentially a powerful tool to monitor the crystal chemistry and correlate phase changes with electrochemical behavior. While several groups have reported Raman spectra of lithium rich oxides, the data show considerable variability in terms of both the vibrational features observed and their interpretation. In this study Raman microscopy is used to investigate lithium-rich manganese-rich cathodes asmore » a function of average charge and electrochemical cycling. LMR-NMC cycled at elevated temperature (60 C) has a modified crystal structure which may account for some of the observed increase in capacity. Contrary to some reports, no growth of a spinel phase is observed. However, analysis of the Raman spectra does indicate the structure of LMR-NMC deviates significantly from an ideal layered phase. The results also highlight the importance of using low laser power and large sample sizes to obtain consistent data sets.« less

  20. Long Cyclic Life in Manganese Oxide-Based Electrodes.

    PubMed

    Wang, Zhaoming; Qin, Qingqing; Xu, Wei; Yan, Jian; Wu, Yucheng

    2016-07-20

    Long cyclic life is very important to the practical application of the pseudocapacitors. A systematic study has been carried out to reveal what key factors and how they affecting the cycling behaviors of manganese oxides. The specific capacitance degradation of MnOx is usually attributed to the so-called "dissolution" issue. Our results indicate that "dissoluted MnOx" is in the form of the "flotsam" derived from the detached active materials instead of Mn(2+) in the solution, which causes color change of electrolyte and the loss of specific capacitance. During the cycling, the morphology of manganese oxides transformed to flower-like flakes regardless of the starting structures. After that, it tends to form nanowires especially at elevated temperatures. According to the relative low electrochemical utility of nanowires, specific capacitance might decrease at this stage. These results put forward new questions on charge storage mechanism. Besides, electrochemical oxidation of MnOx leads to an increase in specific capacitance. The cycling behavior of MnOx is mainly determined by these three factors. Excitingly, a very stable cycling performance with no capacitance degradation over 40 000 cycles has been achieved in MnO2 hierarchical sphere-based electrodes. This study provides insightful understanding of the fundamental cycling behavior of MnOx-based electrodes and useful instructions for developing highly stable supercapacitors. PMID:27347779

  1. Preparation and Characterization of Nanostructured Manganese Oxide for Supercapacitors.

    PubMed

    Jang, Jaeyong; Kim, Taewoo; Choi, Young Il; Park, Inyeong; Lim, Dongwook; Shim, Sang Eun; Baeck, Sung-Hyeon

    2016-05-01

    Nanostructured manganese oxides were synthesized by a sol-gel method using manganese acetate (MnAc2) and citric acid (C6H8O7,) as precursors, and characterized by Brunauer-Emmett-Teller (BET) analysis, Barrett-Joyner-Halenda (BJH), X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) techniques. The nano-rod structure of MnO2 developed gradually when the calcination temperature varied from 380 to 580 degrees C. As the pH increased, the pore size increased, while the specific surface area decreased. The effects of the pH and calcination temperature on the electrochemical properties of the nano-MnO2 electrode, including the supercapacitive behavior, were investigated by cyclic voltammetry (CV) tests. The tests were performed between 0 and 0.8 V versus Ag/AgCl in 1 M Na2SO4 electrolyte at various scan rates (10-200 mVs(-1)). The specific capacitance of the SP-380 sample, prepared at pH 6, was equal to 269.3 Fg(-1). After 300 cycles, approximately a 3.4% increase of the specific capacitance was measured, confirming the excellent cyclability. PMID:27483899

  2. Revisiting an old friend: manganese-based MRI contrast agents

    PubMed Central

    Pan, Dipanjan; Caruthers, Shelton D.; Senpan, Angana; Schmieder, Ann H.; Wickline, Samuel A.; Lanza, Gregory M.

    2011-01-01

    Non-invasive cellular and molecular imaging techniques are emerging as a multidisciplinary field that offers promise in understanding the components, processes, dynamics and therapies of disease at a molecular level. Magnetic resonance imaging (MRI) is an attractive technique due to the absence of radiation and high spatial resolution which makes it advantageous over techniques involving radioisotopes. Typically paramagnetic and superparamagnetic metals are used as contrast materials for MR based techniques. Gadolinium has been the predominant paramagnetic contrast metal until the discovery and association of the metal with nephrogenic systemic fibrosis (NSF) in some patients with severe renal or kidney disease. Manganese was one of the earliest reported examples of paramagnetic contrast material for MRI because of its efficient positive contrast enhancement. In this review manganese based contrast agent approaches will be presented with a particular emphasis on nanoparticulate agents. We have discussed both classically used small molecule based blood pool contrast agents and recently developed innovative nanoparticle-based strategies highlighting a number of successful molecular imaging examples. PMID:20860051

  3. Manganese chlorins immobilized on silica as oxidation reaction catalysts.

    PubMed

    Castro, Kelly A D F; Pires, Sónia M G; Ribeiro, Marcos A; Simões, Mário M Q; Neves, M Graça P M S; Schreiner, Wido H; Wypych, Fernando; Cavaleiro, José A S; Nakagaki, Shirley

    2015-07-15

    Synthetic strategies that comply with the principles of green chemistry represent a challenge: they will enable chemists to conduct reactions that maximize the yield of products with commercial interest while minimizing by-products formation. The search for catalysts that promote the selective oxidation of organic compounds under mild and environmentally friendly conditions constitutes one of the most important quests of organic chemistry. In this context, metalloporphyrins and analogues are excellent catalysts for oxidative transformations under mild conditions. In fact, their reduced derivatives chlorins are also able to catalyze organic compounds oxidation effectively, although they have been still little explored. In this study, we synthesized two chlorins through porphyrin cycloaddition reactions with 1.3-dipoles and prepared the corresponding manganese chlorins (MnCHL) using adequate manganese(II) salts. These MnCHL were posteriorly immobilized on silica by following the sol-gel process and the resulting solids were characterized by powder X-ray diffraction (PXRD), UVVIS spectroscopy, FTIR, XPS, and EDS. The catalytic activity of the immobilized MnCHL was investigated in the oxidation of cyclooctene, cyclohexene and cyclohexane and the results were compared with the ones obtained under homogeneous conditions. PMID:25841060

  4. The Electrical Contact for Higher Manganese Silicide Thermoelectric Material

    NASA Astrophysics Data System (ADS)

    Shi, Xinghua; Zamanipour, Zahra; Vashaee, Daryoosh

    2011-03-01

    The Electrical Contact for Higher Manganese Silicide Thermoelectric Material Xinghua Shi, Zahra Zamanipour, Daryoosh Vashaee Several electrical contact materials for Higher Manganese Silicide (HMS) are introduced. HMS is useful thermoelectric material for medium to high temperature applications. We have investigated several materials including Co, Ni, Cr, Ti, Mo, MnSi, MoSi2, and TiSi2 in search of the best contact material to HMS. The low electrical resistivity and reliability of the contact are two important elements to make a high efficient TE device. Moreover, the contact must maintain its chemical, mechanical, thermal, and electrical properties over a broad range of temperature (20C-700C). The investigated elemental metals failed to make reliable contact in terms of mechanical and chemical stability at high temperature. In contrast, the investigated metal silicides showed superior stability over extended operation at high temperature. The thermal stability and strong mechanical bonding of TiSi2 C54 phase and MnSi were specially observed. Their ohmic contact resistance was also within the range of interest over the whole range of temperature (10-5 -10-4 Ω cm2) . This work was supported by AFOSR High Temperature Materials and NSF under contract CBET0933763.

  5. Sedimentary manganese carbonate deposits of the Molango District, Mexico

    SciTech Connect

    Alexandri, R. Jr.; Force, E.R.; Cannon, W.F.; Spiker, E.C.

    1985-01-01

    A shallow-marine sedimentary manganese carbonate deposit of Oxfordian-Kimmeridgian (Late Jurassic) age in the Molango district of Hidalgo, Mexico, contains one of the world's largest manganese resources. The bed presently mined, 1 to 9 thick and averaging 27% Mn, forms the lowest member of the Chipoco Formation throughout the district. Chipoco Fmn. carbonates and underlying Santiago Fmn. black shale form Taman Group. Deformation is severe but not penetrative. Additional supergene nsutite-pyrolusite deposits have formed on lower Chipoco Fmn. The ore bed is dark, laminated, a fine-grained carbonate rock and consists of pelletal(.)-textured rhodochrosite + minor talc-chlorite, or of rhodochrosite + kutnahorite in graded microlaminae, with 1-5% pyrite and 2-3% organic matter. At Naopa, magnetite locally takes the place of pyrite. Mn carbonates replace calcareous macro- and microfossils. Preservation of laminae suggests anoxic bottom waters during deposition. Paleodepth probably was 100 to 300 m, from sporadic beds with benthic fossils. The anoxic waters were probably rich in dissolved Mn, and may have been saturated with respect to rhodochrosite, leading to replacement of calcareous substrates. Dissolved iron in basin waters was kept low by pyrite precipitation.

  6. Why did Nature choose manganese to make oxygen?

    PubMed Central

    Armstrong, Fraser A

    2007-01-01

    This paper discusses the suitability of manganese for its function in catalysing the formation of molecular oxygen from water. Manganese is an abundant element. In terms of its inherent properties, Mn has a particularly rich redox chemistry compared with other d-block elements, with several oxidizing states accessible. The most stable-state Mn2+ behaves like a Group 2 element—it is mobile, weakly complexing, easily taken up by cells and redox-inactive in simple aqueous media. Only in the presence of suitable ligands does Mn2+ become oxidized, so it provides an uncomplicated building unit for the oxygen-evolving centre (OEC). The intermediate oxidation states Mn(III) and Mn(IV) are strongly complexed by O2− and form robust mixed-valence poly-oxo clusters in which the Mn(IV)/Mn(III) ratio can be elevated, one electron at a time, accumulating oxidizing potential and capacity. The OEC is a Mn4CaOx cluster that undergoes sequential oxidations by P680+ at potentials above 1 V, ultimately to a super-oxidized level that includes one Mn(V) or a Mn(IV)-oxyl radical. The latter is powerfully oxidizing and provides the crucial ‘power stroke’ necessary to generate an O–O bond. This leaves a centre still rich in Mn(IV), ensuring a rapid follow-through to O2. PMID:17971329

  7. [Colloid effects on temporal-spatial variability of iron and manganese in shallow groundwater of garbage contaminated sites].

    PubMed

    Ma, Jie; Li, Hai-Ming; Gu, Xiao-Ming; Li, Yun

    2011-03-01

    Simulation tank experiment was conducted to elucidate the temporal-spatial variability of Iron and Manganese in leachate pollution plumes of water-bearing media. Colloid effects on transport and transformation of Fe and Mn in water-bearing media were determined emphatically. Moreover, the mechanism of Fe and Mn transport and transformation were discussed by the convection-dispersion, dissolution and transport-deposition of colloid. The results show that the total Fe and Mn in leachate pollution plume was 2.82 times and 7.51 times of infiltration leachate due to the dissolution of water-bearing medium. Along the flow direction, Fe and Mn pollution plumes spread, and the central region of plumes gradually widened by the convection-dispersion and dissolution. In the presence of colloid, the average transport velocity of Fe and Mn plumes central axis from 1.17 cm/d and 1.75 cm/d increased to 1.83 cm/d and 2.5 cm/d respectively, colloid had obvious facilitation to the migration of Fe and Mn. PMID:21634196

  8. Leaf cDNA-AFLP analysis of two citrus species differing in manganese tolerance in response to long-term manganese-toxicity

    PubMed Central

    2013-01-01

    Background Very little is known about manganese (Mn)-toxicity-responsive genes in citrus plants. Seedlings of ‘Xuegan’ (Citrus sinensis) and ‘Sour pummelo’ (Citrus grandis) were irrigated for 17 weeks with nutrient solution containing 2 μM (control) or 600 μM (Mn-toxicity) MnSO4. The objectives of this study were to understand the mechanisms of citrus Mn-tolerance and to identify differentially expressed genes, which might be involved in Mn-tolerance. Results Under Mn-toxicity, the majority of Mn in seedlings was retained in the roots; C. sinensis seedlings accumulated more Mn in roots and less Mn in shoots (leaves) than C. grandis ones and Mn concentration was lower in Mn-toxicity C. sinensis leaves compared to Mn-toxicity C. grandis ones. Mn-toxicity affected C. grandis seedling growth, leaf CO2 assimilation, total soluble concentration, phosphorus (P) and magenisum (Mg) more than C. sinensis. Using cDNA-AFLP, we isolated 42 up-regulated and 80 down-regulated genes in Mn-toxicity C. grandis leaves. They were grouped into the following functional categories: biological regulation and signal transduction, carbohydrate and energy metabolism, nucleic acid metabolism, protein metabolism, lipid metabolism, cell wall metabolism, stress responses and cell transport. However, only 7 up-regulated and 8 down-regulated genes were identified in Mn-toxicity C. sinensis ones. The responses of C. grandis leaves to Mn-toxicity might include following several aspects: (1) accelerating leaf senescence; (2) activating the metabolic pathway related to ATPase synthesis and reducing power production; (3) decreasing cell transport; (4) inhibiting protein and nucleic acid metabolisms; (5) impairing the formation of cell wall; and (6) triggering multiple signal transduction pathways. We also identified many new Mn-toxicity-responsive genes involved in biological and signal transduction, carbohydrate and protein metabolisms, stress responses and cell transport. Conclusions Our

  9. Tritium purification via zirconium-manganese-iron alloy getter st 909 in flow processes

    SciTech Connect

    Baker, J.D.; Meikrantz, D.H.; Pawelko, R. J.; Anderl, R.A. |; Tuggle, D.G.

    1995-03-01

    A zirconium-manganese-iron alloy, St 909, was evaluated as a purifier in tritium handling, transport, and storage applications. High efficiency removal of CH{sub 4}, CO, CO{sub 2}, NH{sub 3}, and O{sub 2} was observed at concentrations of 0.1 to 1% in helium. Gas streams at 100 to 5000 sccm were passed through getters operated at 500-800{degree}C. On-getter residence times of two seconds were required to achieve > 99% removal of these reactive impurities. At this removal efficiency level, the individual impurity capacity of 100 g of St 909 purifier at 800{degree}C was 0.59, 0.28, 0.19, 0.14 and 0.12 moles of CH{sub 4}, CO, CO{sub 2}, O{sub 2} and NH{sub 3}, respectively. Hydrogen containing gases, CH{sub 4} and NH{sub 3}, were cracked on the purifier and the resultant elemental hydrogen was released. Only 8{+-}2 scc of H{sub 2} were retained on 100 g of St 909 at 800{degree}C. These features suggest that this alloy can be employed as an efficient purifier for hydrogen isotopes in inert gas, nitrogen, or perhaps even H, D, or T streams. 12 refs., 4 figs., 1 tab.

  10. A novel manganese complex selectively induces malignant glioma cell death by targeting mitochondria

    PubMed Central

    Geng, Ji; Li, Jing; Huang, Tao; Zhao, Kaidi; Chen, Qiuyun; Guo, Wenjie; Gao, Jing

    2016-01-01

    Despite advances in treatment, malignant glioma commonly exhibits recurrence, subsequently leading to a poor prognosis. As manganese (Mn) compounds can be transported by the transferrin-transferrin receptor system, the present study synthesized and examined the potential use of Adpa-Mn as a novel antitumor agent. Adpa-Mn time and dose-dependently inhibited U251 and C6 cell proliferation; however, it had little effect on normal astrocytes. Apoptosis was significantly elevated following treatment with Adpa-Mn, as detected by chromatin condensation, Annexin V/propidium iodide staining, cytochrome c release from mitochondria to the cytoplasm, and the activation of caspases-9, -7 and -3 and poly (ADP-ribose) polymerase. In addition, Adpa-Mn enhanced fluorescence intensity of monodansylcadaverine and elevated the expression levels of the autophagy-related protein microtubule-associated protein 1 light chain 3. Pretreatment with the autophagy inhibitors 3-methyladenine and chloroquine enhanced Adpa-Mn-induced cell inhibition, thus indicating that autophagy has an essential role in this process. Furthermore, evidence of mitochondrial dysfunction was detected in the Adpa-Mn-treated group, including disrupted membrane potential, elevated levels of reactive oxygen species (ROS) and depleted adenosine triphosphate. Conversely, treatment with the mitochondrial permeability transition inhibitor cyclosporin A reversed Adpa-Mn-induced ROS production, mitochondrial damage and cell apoptosis, thus suggesting that Adpa-Mn may target the mitochondria. Taken together, these data suggested that Adpa-Mn may be considered for use as a novel anti-glioma therapeutic option. PMID:27432745

  11. Anomalous hole injection deterioration of organic light-emitting diodes with a manganese phthalocyanine layer

    SciTech Connect

    Lee, Hyunbok; Lee, Jeihyun; Yi, Yeonjin; Cho, Sang Wan; Kim, Jeong Won

    2015-01-21

    Metal phthalocyanines (MPcs) are well known as an efficient hole injection layer (HIL) in organic devices. They possess a low ionization energy, and so the low-lying highest occupied molecular orbital (HOMO) gives a small hole injection barrier from an anode in organic light-emitting diodes. However, in this study, we show that the hole injection characteristics of MPc are not only determined by the HOMO position but also significantly affected by the wave function distribution of the HOMO. We show that even with the HOMO level of a manganese phthalocyanine (MnPc) HIL located between the Fermi level of an indium tin oxide anode and the HOMO level of a N,N′-bis(1-naphthyl)-N,N′-diphenyl-1,1′-biphenyl-4,4′-diamine hole transport layer the device performance with the MnPc HIL is rather deteriorated. This anomalous hole injection deterioration is due to the contracted HOMO wave function, which leads to small intermolecular electronic coupling. The origin of this contraction is the significant contribution of the Mn d-orbital to the MnPc HOMO.

  12. Half-Metallic Properties of Single-Walled Polymeric Manganese Phthalocyanine Nanotubes

    PubMed Central

    Jiang, Hongbin; Bai, Meilin; Wei, Peng; Sun, Lili; Shen, Ziyong; Hou, Shimin

    2012-01-01

    We present a theoretical study of the electronic and magnetic properties of single-walled manganese phthalocyanine (MnPc) nanotubes which can be thought of as rolled-up ribbons of the two-dimensional (2D) polymeric MnPc sheet. Our density functional theory calculations show that all of the MnPc nanotubes investigated here are half-metals with 100% spin polarization around the Fermi level. Following the increase of the tube diameter, the number of spin-down energy bands of MnPc nanotubes is always increased while the spin-up band gap of MnPc nanotubes approaches that of the 2D MnPc sheet in an oscillatory manner. Because the half-metallic character of MnPc nanotubes is deeply rooted in the distribution of electrons in the energy bands dominated by the Mn 3d atomic orbitals, adsorption of CO molecules on the Mn ions leads to a redistribution of electrons in the Mn 3d orbitals and thus can tune precisely the spin state and electronic transport properties of MnPc nanotubes, demonstrating promising applications of MnPc nanotubes in future molecular spintronics and single-molecule sensors. PMID:23012498

  13. Manganese-Induced Parkinsonism Is Not Idiopathic Parkinson’s Disease: Environmental and Genetic Evidence

    PubMed Central

    Guilarte, Tomás R.; Gonzales, Kalynda K.

    2015-01-01

    Movement abnormalities caused by chronic manganese (Mn) intoxication clinically resemble but are not identical to those in idiopathic Parkinson’s disease. In fact, the most successful parkinsonian drug treatment, the dopamine precursor levodopa, is ineffective in alleviating Mn-induced motor symptoms, implying that parkinsonism in Mn-exposed individuals may not be linked to midbrain dopaminergic neuron cell loss. Over the last decade, supporting evidence from human and nonhuman primates has emerged that Mn-induced parkinsonism partially results from damage to basal ganglia nuclei of the striatal “direct pathway” (ie, the caudate/putamen, internal globus pallidus, and substantia nigra pars reticulata) and a marked inhibition of striatal dopamine release in the absence of nigrostriatal dopamine terminal degeneration. Recent neuroimaging studies have revealed similar findings in a particular group of young drug users intravenously injecting the Mn-containing psychostimulant ephedron and in individuals with inherited mutations of the Mn transporter gene SLC30A10. This review will provide a detailed discussion about the aforementioned studies, followed by a comparison with their rodent analogs and idiopathic parkinsonism. Together, these findings in combination with a limited knowledge about the underlying neuropathology of Mn-induced parkinsonism strongly support the need for a more complete understanding of the neurotoxic effects of Mn on basal ganglia function to uncover the appropriate cellular and molecular therapeutic targets for this disorder. PMID:26220508

  14. Metals, Oxidative Stress and Neurodegeneration: A focus on Iron, Manganese and Mercury

    PubMed Central

    Farina, Marcelo; Avila, Daiana Silva; da Rocha, João Batista Teixeira

    2013-01-01

    Essential metals are crucial for the maintenance of cell homeostasis. Among the 23 elements that have known physiological functions in humans, 12 are metals, including iron (Fe) and manganese (Mn). Nevertheless, excessive exposure to these metals may lead to pathological conditions, including neurodegeneration. Similarly, exposure to metals that do not have known biological functions, such as mercury (Hg), also present great health concerns. This reviews focuses on the neurodegenerative mechanisms and effects of Fe, Mn and Hg. Oxidative stress (OS), particularly in mitochondria, is a common feature of Fe, Mn and Hg toxicity. However, the primary molecular targets triggering OS are distinct. Free cationic iron is a potent pro-oxidant and can initiate a set of reactions that form extremely reactive products, such as OH•. Mn can oxidize dopamine (DA), generating reactive species and also affect mitochondrial function, leading to accumulation of metabolites and culminating with OS. Cationic Hg forms have strong affinity for nucleophiles, such as –SH and –SeH. Therefore, they target critical thiol- and selenol-molecules with antioxidant properties. Finally, we address the main sources of exposure to these metals, their transport mechanisms into the brain, and therapeutic modalities to mitigate their neurotoxic effects. PMID:23266600

  15. Anchoring Nanostructured Manganese Fluoride on Few-Layer Graphene Nanosheets as Anode for Enhanced Lithium Storage.

    PubMed

    Rui, Kun; Wen, Zhaoyin; Lu, Yan; Shen, Chen; Jin, Jun

    2016-01-27

    Manganese fluoride (MnF2)/few-layer graphene nanosheets (GNS) composites are successfully prepared via a facile solvothermal method. It is found that in situ formed tetragonal MnF2 submicron crystals (50-200 nm) with good crystallinity anchoring homogeneously onto conducting GNS, allows the electrically insulating MnF2 particles to be wired up to the current collector with enhanced electron transport pathway. The MnF2/GNS composites act as anode in LIBs and display prominently improved electrochemical performance in comparison to that of pure MnF2, on account of the close interactions between the underlying graphene nanosheets and MnF2 particles grown atop. Distinctly enhanced capacity as high as 489 mAh g(-1) after 100 cycles can be obtained at 600 mA g(-1), while the self-activation process can be greatly accelerated at 6000 mA g(-1) with a maximum specific capacity of 530 mAh g(-1). With long cycling stability for 4000 cycles at 6000 mA g(-1), the MnF2/GNS composite can be deemed as an attractive candidate anode for high-capacity, long cycle life, and environmentally friendly LIBs. PMID:26727406

  16. Geochemistry and crystallochemistry of oceanic hydrothermal manganese oxyhydroxides showing Mn-Cu association

    SciTech Connect

    Stouff, P.; Boulegue, J. )

    1989-04-01

    Hydrothermal iron and manganese oxides have been found in association with sulfides dredged on the E.P.R. near 7{degree}N. The Mn phase, mainly a 10-7 {angstrom} phyllomanganate, presents a very important enrichment in Cu (up to 30% as weight of oxide). The Fe phase, mainly hydro-goethite, has a very low content of metals of economic interest. Also Mn-Cu oxide particles have been collected in sediment traps near the hydrothermal vents at 13{degree}N. Using the Mn oxide samples of 7{degree}N, Cu shows two simultaneous oxidation states: +I and +II (ESCA and XAS edge measurements). Cu is adsorbed on the Mn(O,OH){sub 2} layers and partially belongs to the water layers (EXAFS results). This seems to be the first report of naturally occurring Cu-buserite in this environment. Lead isotope abundances, the presence of Cu(I), thermodynamic considerations on the stability of the Mn-Cu oxyhydroxides and unsuccessful attempts made with synthetic 10-7 {angstrom} phyllomanganates (buserite and birnessite types) at low temperature in order to stabilize Cu(I) and incorporate it in the interlamellar space of the manganate, lead the authors to accept a high temperature origin for the formation of the Mn-Cu oxyhydroxides. They present a transport model for Cu and Mn precipitation from oceanic hydrothermal fluid, to explain the formation of Mn-Cu oxyhydroxides.

  17. Molecular-Level Processes Governing the Interaction of Contaminants with Iron and Manganese Oxides - Final Report

    SciTech Connect

    Brown Jr., G. E.; Chambers, S. A.

    1999-10-31

    Many of the inorganic and organic contaminants present in sediments at DOE sites can be altered or destroyed by reduction and oxidation (redox) reactions occurring at mineral surfaces. A fundamental understanding of such redox processes provided by molecular-level studies on structurally and compositionally well-defined mineral surfaces will lead to: (i) improved models of contaminant fate and transport in geochemical systems, and (ii) optimized manipulation of these processes for remediation purposes. To contribute to this understanding, we will study, both experimentally and theoretically, redox processes involving three important contaminants - chromate ion, carbon tetrachloride, and trichloroethene TCE, on the following iron and manganese oxides - hematite, magnetite, maghemite, and pyrolusite. These oxides and their hydroxylated analogs commonly occur as coatings on minerals or as interfaces in the subsurface environment. Single-crystal surfaces of these oxides will be synthesized in carefully controlled fashion by molecular beam epitaxy. These surfaces, as well as high surface are powdered samples of these oxides, will be used in spectroscopic and kinetic experiments in both aqueous and gas phases. Our goal is to identify products and to determine the kinetics and mechanisms of surface-catalyzed redox reaction of Cr(VI) and CR(III), and the reductive dechlorination of carbon tetrachloride and TCE. The combination of theory and experiment will provide the base information needed to scale from the molecular level to the microscopic grain level minerals.

  18. Mechanical Alloying and Spark Plasma Sintering of Higher Manganese Silicides for Thermoelectric Applications

    NASA Astrophysics Data System (ADS)

    Sadia, Yatir; Dinnerman, Liron; Gelbstein, Yaniv

    2013-07-01

    The present challenges in the energy crisis require finding new ways to reduce consumption of fossil fuels. Thermoelectrics can help reduce fuel consumption by producing electricity from waste heat. The higher manganese silicides (HMS) have shown promise in this field as inexpensive, nontoxic, and highly stable p-type thermoelectric materials. One of the production techniques for HMS is mechanical alloying by ball milling. In this research the effect of the ball-milling duration and speed on the phases produced was studied. Mn and Si powders were milled at speeds of 200 RPM to 800 RPM for 1 h to 7 h. X-ray diffraction (XRD) results of the samples prepared using mechanical alloying show deterioration into the MnSi phase. The sample that underwent 5 h of milling at 800 RPM showed the greatest amount of HMS phase and was subsequently spark plasma sintered. The sample showed insufficient thermoelectric properties ( ZT ≈ 0.1 at 450°C), compared with either solid-state reaction samples showing ZT ≈ 0.4 or cast samples showing ZT ≈ 0.63 at 450°C. The reduced ZT values of the mechanically alloyed and spark-plasma-sintered samples were attributed to the high relative amount of MnSi phase. The correlation between the relative amount of MnSi and the transport properties is described in detail.

  19. Particulate manganese dynamics in Gulf Stream warm-core rings and surrounding waters of the NW Atlantic

    SciTech Connect

    Bishop, J.K.B.; Fleisher, M.Q. )

    1987-10-01

    Manganese has been measured in size-fractionated particulate matter profiles obtained by large volume in situ filtration of the upper 1000 m of the N.W. Atlantic as part of the Warm Core Rings Experiment (WCRE) in 1982. Environments sampled included Warm Core Rings (WCR) 82B and 82H, the entrainment zone at the edge of these rings, the Slope Water surrounding rings, and the Gulf Stream (GS) and Sargasso Sea (SS) from which the rings formed. Manganese concentrations ranged from 10 pmol kg{sup {minus}1} to 10,000 pmol kg{sup {minus}1} with the extreme values observed in the quasi-isolated core waters of WCR 82B and in a tongue of shelf water at the periphery of WCR 82B, respectively. The majority of the Mn was in the 1-53 {mu}m particle size fraction and most Mn was probably close to 1 {mu}m in size. Mn showed no correlation with major biogenic phases indicating that formation by local biological processes was not an important source. Instead, most particulate Mn present in the waters sampled originated in reducing sediments at the continental margin. Calculations show that WCRs cause offshore particulate Mn transports from the continental margin between 66{degree}W and Cape Hatteras of 8.5 {times} 10{sup 4} to 14 {times} 10{sup 4} mol d{sup {minus}1} with most derived from the continental shelf. Only 4% of the shelf derived Mn becomes entrained in WCRs and the rest is left 8to disperse in the Slope Water or enter the circulation of the Gulf stream. The WCR-induced offshore Mn transports may account for a large fraction of the Mn flux to sediments on the continental slope and upper continental rise.

  20. Reduction Kinetics of Manganese Dioxide by Geobacter Sulfurreducens and Associated Biofilm Morphology in a Flow-Through Reactor

    NASA Astrophysics Data System (ADS)

    Berns, E.; Werth, C. J.; Valocchi, A. J.; Sanford, R. A.

    2015-12-01

    Biogeochemical interactions have been investigated extensively to characterize natural nutrient cycling and predict contaminant transport in surface and groundwater. Dissimilatory metal reducing bacteria, many of which form biofilms, play an important role in reducing a variety of metals in these systems. It has been shown that biofilm morphology is impacted by flow conditions, but there has been little work that explores how reduction kinetics change as a result of these different morphologies. Different flow rates may affect physical properties of the biofilm that influence the rate of substrate reduction. We introduce an approach to calculate changes in Monod kinetic parameters while simultaneously evaluating biofilm morphologies under different flow rates. A vertical, cylindrical flow cell with removable glass slide sections coated in manganese dioxide (electron acceptor) was used to grow a biofilm of Geobacter sulfurreducens with acetate as the electron donor under both high (50 mL/hr) and low (5 mL/h) flow rates. The removable sections allowed for visualization of the biofilm at different time points with a confocal microscope, and quantification of the biomass on the surface using a combination of a protein assay and image analysis. Data collected from the experiments was used to determine yield and specific growth rate at the different flow rates, and a simple numerical model was used to estimate the half saturation constant of manganese dioxide at both flow rates. A smaller half saturation constant was estimated at the higher flow rate, indicating that the biofilm was more efficient in the high flow system, but a strong correlation between morphology and the faster reduction rate was not observed. Monod kinetic parameters are important for the development of accurate nutrient cycling and contaminant transport models in natural environments, and understanding how they are impacted by flow will be important for the development of new, improved models.