Science.gov

Sample records for iron transport systems

  1. Mammalian iron transport.

    PubMed

    Anderson, Gregory Jon; Vulpe, Christopher D

    2009-10-01

    Iron is essential for basic cellular processes but is toxic when present in excess. Consequently, iron transport into and out of cells is tightly regulated. Most iron is delivered to cells bound to plasma transferrin via a process that involves transferrin receptor 1, divalent metal-ion transporter 1 and several other proteins. Non-transferrin-bound iron can also be taken up efficiently by cells, although the mechanism is poorly understood. Cells can divest themselves of iron via the iron export protein ferroportin in conjunction with an iron oxidase. The linking of an oxidoreductase to a membrane permease is a common theme in membrane iron transport. At the systemic level, iron transport is regulated by the liver-derived peptide hepcidin which acts on ferroportin to control iron release to the plasma. PMID:19484405

  2. The mammalian transferrin-independent iron transport system may involve a surface ferrireductase activity.

    PubMed Central

    Jordan, I; Kaplan, J

    1994-01-01

    Mammalian cells accumulate iron from ferric citrate or ferric nitrilotriacetate through the activity of a transferrin-independent iron transport system [Sturrock, Alexander, Lamb, Craven and Kaplan (1990) J. Biol. Chem. 265, 3139-3145]. The uptake system might recognize and transport ferric-anion complexes, or cells may reduce ferric iron at the surface and then transport ferrous iron. To distinguish between these possibilities we exposed cells to either [59Fe]ferric citrate or ferric [14C]citrate and determined whether accumulation of iron was accompanied by the obligatory accumulation of citrate. In HeLa cells and human skin fibroblasts the rate of accumulation of iron was three to five times greater than that of citrate. Incubation of fibroblasts with ferric citrate or ferric ammonium citrate resulted in an enhanced accumulation of iron and citrate; the molar ratio of accumulation approaching unity. A similar rate of citrate accumulation, however, was observed when ferric citrate-incubated cells were exposed to [14C]citrate alone. Further studies demonstrated the independence of iron and citrate accumulation: addition of unlabelled citrate to cells decreased the uptake of labelled citrate without affecting the accumulation of 59Fe; iron uptake was decreased by the addition of ferrous chelators whereas the uptake of citrate was unaffected; reduction of ferric iron by ascorbate increased the uptake of iron but had no effect on the uptake of citrate. When HeLa cells were depleted of calcium, iron uptake decreased, but there was little effect on citrate uptake. These results indicate that transport of iron does not require the obligatory transport of citrate and vice versa. The mammalian transferrin-independent iron transport system appears functionally similar to iron transport systems in both the bacterial and plant kingdoms which require the activities of both a surface reductase and a ferrous metal transporter. PMID:7945215

  3. Chemical Interference with Iron Transport Systems to Suppress Bacterial Growth of Streptococcus pneumoniae

    PubMed Central

    Zhang, Liang; Li, Nan; Han, Junlong; Zhang, Jing; Sun, Xuesong; He, Qing-Yu

    2014-01-01

    Iron is an essential nutrient for the growth of most bacteria. To obtain iron, bacteria have developed specific iron-transport systems located on the membrane surface to uptake iron and iron complexes such as ferrichrome. Interference with the iron-acquisition systems should be therefore an efficient strategy to suppress bacterial growth and infection. Based on the chemical similarity of iron and ruthenium, we used a Ru(II) complex R-825 to compete with ferrichrome for the ferrichrome-transport pathway in Streptococcus pneumoniae. R-825 inhibited the bacterial growth of S. pneumoniae and stimulated the expression of PiuA, the iron-binding protein in the ferrichrome-uptake system on the cell surface. R-825 treatment decreased the cellular content of iron, accompanying with the increase of Ru(II) level in the bacterium. When the piuA gene (SPD_0915) was deleted in the bacterium, the mutant strain became resistant to R-825 treatment, with decreased content of Ru(II). Addition of ferrichrome can rescue the bacterial growth that was suppressed by R-825. Fluorescence spectral quenching showed that R-825 can bind with PiuA in a similar pattern to the ferrichrome-PiuA interaction in vitro. These observations demonstrated that Ru(II) complex R-825 can compete with ferrichrome for the ferrichrome-transport system to enter S. pneumoniae, reduce the cellular iron supply, and thus suppress the bacterial growth. This finding suggests a novel antimicrobial approach by interfering with iron-uptake pathways, which is different from the mechanisms used by current antibiotics. PMID:25170896

  4. Cellular iron transport.

    PubMed

    Garrick, Michael D; Garrick, Laura M

    2009-05-01

    Iron has a split personality as an essential nutrient that also has the potential to generate reactive oxygen species. We discuss how different cell types within specific tissues manage this schizophrenia. The emphasis in enterocytes is on regulating the body's supply of iron by regulating transport into the blood stream. In developing red blood cells, adaptations in transport manage the body's highest flux of iron. Hepatocytes buffer the body's stock of iron. Macrophage recycle the iron from effete red cells among other iron management tasks. Pneumocytes provide a barrier to prevent illicit entry that, when at risk of breaching, leads to a need to handle the dangers in a fashion essentially shared with macrophage. We also discuss or introduce cell types including renal cells, neurons, other brain cells, and more where our ignorance, currently still vast, needs to be removed by future research. PMID:19344751

  5. Comparative Genomics of Iron-Transporting Systems in Bacillus cereus Strains and Impact of Iron Sources on Growth and Biofilm Formation

    PubMed Central

    Hayrapetyan, Hasmik; Siezen, Roland; Abee, Tjakko; Nierop Groot, Masja

    2016-01-01

    Iron is an important element for bacterial viability, however it is not readily available in most environments. We studied the ability of 20 undomesticated food isolates of Bacillus cereus and two reference strains for capacity to use different (complex) iron sources for growth and biofilm formation. Studies were performed in media containing the iron scavenger 2,2-Bipyridine. Transcriptome analysis using B. cereus ATCC 10987 indeed showed upregulation of predicted iron transporters in the presence of 2,2-Bipyridine, confirming that iron was depleted upon its addition. Next, the impact of iron sources on growth performance of the 22 strains was assessed and correlations between growth stimulation and presence of putative iron transporter systems in the genome sequences were analyzed. All 22 strains effectively used Fe citrate and FeCl3 for growth, and possessed genes for biosynthesis of the siderophore bacillibactin, whereas seven strains lacked genes for synthesis of petrobactin. Hemoglobin could be used by all strains with the exception of one strain that lacked functional petrobactin and IlsA systems. Hemin could be used by the majority of the tested strains (19 of 22). Notably, transferrin, ferritin, and lactoferrin were not commonly used by B. cereus for growth, as these iron sources could be used by 6, 3, and 2 strains, respectively. Furthermore, biofilm formation was found to be affected by the type of iron source used, including stimulation of biofilms at liquid-air interphase (FeCl3 and Fe citrate) and formation of submerged type biofilms (hemin and lactoferrin). Our results show strain variability in the genome-encoded repertoire of iron-transporting systems and differences in efficacy to use complex iron sources for growth and biofilm formation. These features may affect B. cereus survival and persistence in specific niches. PMID:27375568

  6. Iron transport and signaling in plants.

    PubMed

    Curie, Catherine; Briat, Jean-François

    2003-01-01

    Cellular and whole organism iron homeostasis must be balanced to supply enough iron for metabolism and to avoid excessive, toxic levels. To perform iron uptake from the environment, iron distribution to various organs and tissues, and iron intracellular compartmentalization, various membranes must be crossed by this metal. The uptake and transport of iron under physiological conditions require particular processes such as chelation or reduction because ferric iron has a very low solubility. The molecular actors involved in iron acquisition from the soil have recently been characterized. A few candidates belonging to various gene families are hypothesized to play major roles in iron distribution throughout the plant. All these transport activities are tightly regulated at transcriptional and posttranslational levels, according to the iron status of the plant. These coordinated regulations result from an integration of local and long-distance transduction pathways. PMID:14509968

  7. OPT3 is a phloem-specific iron transporter that is essential for systemic iron signaling and redistribution of iron and cadmium in arabidopsis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Iron is essential for both plant growth and human health and nutrition. Cadmium, on the other hand, is a non-essential and highly toxic element that competes with iron for uptake and partitioning in plant tissues, posing a threat to crop productivity and human health. Knowledge of signaling mechanis...

  8. Coordination Chemistry of Microbial Iron Transport.

    PubMed

    Raymond, Kenneth N; Allred, Benjamin E; Sia, Allyson K

    2015-09-15

    with the characterization of what are now called siderocalins. Initially found as a protein of the human innate immune system, these proteins bind both ferric and apo-siderophores to inactivate the siderophore transport system and hence deny iron to an invading pathogenic microbe. Siderocalins also can play a role in iron transport of the host, particularly in the early stages of fetal development. Finally, it is speculated that the molecular targets of siderocalins in different species differ based on the siderophore structures of the most important bacterial pathogens of those species. PMID:26332443

  9. Coordination Chemistry of Microbial Iron Transport

    PubMed Central

    2016-01-01

    has emerged with the characterization of what are now called siderocalins. Initially found as a protein of the human innate immune system, these proteins bind both ferric and apo-siderophores to inactivate the siderophore transport system and hence deny iron to an invading pathogenic microbe. Siderocalins also can play a role in iron transport of the host, particularly in the early stages of fetal development. Finally, it is speculated that the molecular targets of siderocalins in different species differ based on the siderophore structures of the most important bacterial pathogens of those species. PMID:26332443

  10. Iron uptake and transport across physiological barriers.

    PubMed

    Duck, Kari A; Connor, James R

    2016-08-01

    Iron is an essential element for human development. It is a major requirement for cellular processes such as oxygen transport, energy metabolism, neurotransmitter synthesis, and myelin synthesis. Despite its crucial role in these processes, iron in the ferric form can also produce toxic reactive oxygen species. The duality of iron's function highlights the importance of maintaining a strict balance of iron levels in the body. As a result, organisms have developed elegant mechanisms of iron uptake, transport, and storage. This review will focus on the mechanisms that have evolved at physiological barriers, such as the intestine, the placenta, and the blood-brain barrier (BBB), where iron must be transported. Much has been written about the processes for iron transport across the intestine and the placenta, but less is known about iron transport mechanisms at the BBB. In this review, we compare the established pathways at the intestine and the placenta as well as describe what is currently known about iron transport at the BBB and how brain iron uptake correlates with processes at these other physiological barriers. PMID:27457588

  11. The placenta: the forgotten essential organ of iron transport.

    PubMed

    Cao, Chang; Fleming, Mark D

    2016-07-01

    Optimal iron nutrition in utero is essential for development of the fetus and helps establish birth iron stores adequate to sustain growth in early infancy. In species with hemochorial placentas, such as humans and rodents, iron in the maternal circulation is transferred to the fetus by directly contacting placental syncytiotrophoblasts. Early kinetic studies provided valuable data on the initial uptake of maternal transferrin, an iron-binding protein, by the placenta. However, the remaining steps of iron trafficking across syncytiotrophoblasts and through the fetal endothelium into the fetal blood remain poorly characterized. Over the last 20 years, identification of transmembrane iron transporters and the iron regulatory hormone hepcidin has greatly expanded the knowledge of cellular iron transport and its regulation by systemic iron status. In addition, emerging human and animal data demonstrating comprised fetal iron stores in severe maternal iron deficiency challenge the classic dogma of exclusive fetal control over the transfer process and indicate that maternal and local signals may play a role in regulating this process. This review compiles current data on the kinetic, molecular, and regulatory aspects of placental iron transport and considers new questions and knowledge gaps raised by these advances. PMID:27261274

  12. Ferrous iron transport in Streptococcus mutans

    SciTech Connect

    Evans, S.L.; Arcenaeux, J.E.L.; Byers, B.R.; Martin, M.E.; Aranha, H.

    1986-12-01

    Radioiron uptake from /sup 59/FeCl/sub 3/ by Streptococcus mutans OMZ176 was increased by anaerobiosis, sodium ascorbate, and phenazine methosulfate (PMS), although there was a 10-min lag before PMS stimulation was evident. The reductant ascorbate may have provided ferrous iron. The PMS was reduced by the cells, and the reduced PMS then may have generated ferrous iron for transport; reduced PMS also may have depleted dissolved oxygen. It was concluded that S. mutans transports only ferrous iron, utilizing reductants furnished by glucose metabolism to reduce iron prior to its uptake.

  13. Iron transport in Mycobacterium smegmatis: uptake of iron from ferric citrate

    SciTech Connect

    Messenger, A.J.M.; Ratledge, C.

    1982-01-01

    In mycobacterial growth medium 40 to 400 ..mu..M citrate was required to solubilize 2 ..mu..M /sup 55/Fe. This solubilized /sup 55/Fe was taken up into both iron-deficient and iron-sufficient washed cell suspensions of Mycobacterium smegmatis and Mycobacterium bovis BCG. Although the /sup 55/Fe was taken up into the cell, the citrate was not. The uptake system with M. smegmatis was not inhibited by electron transport inhibitors, uncouplers of oxidative phosphorylation, or thiol reagents and was saturable with iron at approximately 35 ..mu..M. The system was independent of the iron transport systems already known to exist in M. smegmatis: i.e., the two exochelin routes of assimilation as well as the mycobactin-salicylate system. It was not induced by the presence of 400 ..mu..M citrate in the growth medium, nor did the presence of citrate in the medium affect the production of either exochelin or mycobactin.

  14. An ABC Transporter System of Yersinia pestis Allows Utilization of Chelated Iron by Escherichia coli SAB11

    PubMed Central

    Bearden, Scott W.; Staggs, Teanna M.; Perry, Robert D.

    1998-01-01

    The acquisition of iron is an essential component in the pathogenesis of Yersinia pestis, the agent of bubonic and pneumonic plague. A cosmid library derived from the genomic DNA of Y. pestis KIM6+ was used for transduction of an Escherichia coli mutant (SAB11) defective in the biosynthesis of the siderophore enterobactin. Recombinant plasmids which had a common 13-kb BamHI fragment were isolated from SAB11 transductants in which growth but not enterobactin synthesis was restored on media containing the iron chelator EDDA [ethylenediamine-di(o-hydroxyphenyl acetic acid)]. Subcloning and transposon mutagenesis revealed a 5.6-kb region, designated yfe, essential for SAB11 growth stimulation. In vitro transcription-translation analysis identified polypeptides of 18, 29.5, 32, and 33 kDa encoded by the yfe locus. Sequence analysis shows this locus to be comprised of five genes in two separate operons which have potential Fur-binding sequences in both promoters. A putative polycistronic operon, yfeABCD, is Fur regulated and responds to iron and manganese. A functional Fur protein is required for the observed manganese repression of this operon. This operon encodes polypeptides which have strong similarity to the ATP-binding cassette (ABC) family of transporters and include a periplasmic binding protein (YfeA), an ATP-binding protein (YfeB), and two integral membrane proteins (YfeC and -D), which likely function in the acquisition of inorganic iron and possibly other ions. The ∼21-kDa protein encoded by the separately transcribed yfeE gene may be located in the cell envelope, since a yfeE::TnphoA fusion is PhoA+. Mutations in this gene abrogate growth of SAB11 on iron-chelated media. PMID:9495751

  15. Involvement of NRAMP1 from Arabidopsis thaliana in iron transport.

    PubMed Central

    Curie, C; Alonso, J M; Le Jean, M; Ecker, J R; Briat, J F

    2000-01-01

    Nramp genes code for a widely distributed class of proteins involved in a variety of processes, ranging from the control of susceptibility to bacterial infection in mammalian cells and taste behaviour in Drosophila to manganese uptake in yeast. Some of the NRAMP proteins in mammals and in yeast are capable of transporting metal ions, including iron. In plants, iron transport was shown to require a reduction/Fe(II) transport system. In Arabidopsis thaliana this process involves the IRT1 and Fro2 genes. Here we report the sequence of five NRAMP proteins from A. thaliana. Sequence comparison suggests that there are two classes of NRAMP proteins in plants: A. thaliana (At) NRAMP1 and Oriza sativa (Os) NRAMP1 and 3 (two rice isologues) represent one class, and AtNRAMP2-5 and OsNRAMP2 the other. AtNramp1 and OsNramp1 are able to complement the fet3fet4 yeast mutant defective both in low- and high-affinity iron transports, whereas AtNramp2 and OsNramp2 fail to do so. In addition, AtNramp1 transcript, but not AtNramp2 transcript, accumulates in response to iron deficiency in roots but not in leaves. Finally, overexpression of AtNramp1 in transgenic A. thaliana plants leads to an increase in plant resistance to toxic iron concentration. Taken together, these results demonstrate that AtNramp1 participates in the control of iron homoeostasis in plants. PMID:10769179

  16. Involvement of NRAMP1 from Arabidopsis thaliana in iron transport.

    PubMed

    Curie, C; Alonso, J M; Le Jean, M; Ecker, J R; Briat, J F

    2000-05-01

    Nramp genes code for a widely distributed class of proteins involved in a variety of processes, ranging from the control of susceptibility to bacterial infection in mammalian cells and taste behaviour in Drosophila to manganese uptake in yeast. Some of the NRAMP proteins in mammals and in yeast are capable of transporting metal ions, including iron. In plants, iron transport was shown to require a reduction/Fe(II) transport system. In Arabidopsis thaliana this process involves the IRT1 and Fro2 genes. Here we report the sequence of five NRAMP proteins from A. thaliana. Sequence comparison suggests that there are two classes of NRAMP proteins in plants: A. thaliana (At) NRAMP1 and Oriza sativa (Os) NRAMP1 and 3 (two rice isologues) represent one class, and AtNRAMP2-5 and OsNRAMP2 the other. AtNramp1 and OsNramp1 are able to complement the fet3fet4 yeast mutant defective both in low- and high-affinity iron transports, whereas AtNramp2 and OsNramp2 fail to do so. In addition, AtNramp1 transcript, but not AtNramp2 transcript, accumulates in response to iron deficiency in roots but not in leaves. Finally, overexpression of AtNramp1 in transgenic A. thaliana plants leads to an increase in plant resistance to toxic iron concentration. Taken together, these results demonstrate that AtNramp1 participates in the control of iron homoeostasis in plants. PMID:10769179

  17. The liver: conductor of systemic iron balance

    PubMed Central

    Meynard, Delphine; Babitt, Jodie L.

    2014-01-01

    Iron is a micronutrient essential for almost all organisms: bacteria, plants, and animals. It is a metal that exists in multiple redox states, including the divalent ferrous (Fe2+) and the trivalent ferric (Fe3+) species. The multiple oxidation states of iron make it excellent for electron transfer, allowing iron to be selected during evolution as a cofactor for many proteins involved in central cellular processes including oxygen transport, mitochondrial respiration, and DNA synthesis. However, the redox cycling of ferrous and ferric iron in the presence of H2O2, which is physiologically present in the cells, also leads to the production of free radicals (Fenton reaction) that can attack and damage lipids, proteins, DNA, and other cellular components. To meet the physiological needs of the body, but to prevent cellular damage by iron, the amount of iron in the body must be tightly regulated. Here we review how the liver is the central conductor of systemic iron balance and show that this central role is related to the secretion of a peptide hormone hepcidin by hepatocytes. We then review how the liver receives and integrates the many signals that report the body’s iron needs to orchestrate hepcidin production and maintain systemic iron homeostasis. PMID:24200681

  18. Integrated gasification iron-air electrical system

    SciTech Connect

    Brown, J.T.

    1988-05-17

    An integrated, gasification, iron-air electrical system, capable of generating electrical energy from a carbonaceous material is described comprising: (A) a gasification means for carbonaceous materials comprising at least one gasification reactor, where a carbonaceous material is contacted and reacted with a gaseous medium containing steam and air, at a temperature and for a time effective to gasify the carbonaceous material and produce a hot gaseous reaction product comprising CO and H/sub 2/; (B) an iron-air cell containing at least one discharged iron electrode; (C) means to remove the discharged iron electrode from the cell of (B), and contact it with the gaseous reaction product produced in (A); (D) the discharged iron electrode removed from the cell of (B), containing material consisting essentially of Fe and Fe(OH)/sub 2/, which electrode is contacted with the hot gaseous reaction product produced in the gasification reactor of (A), directly, at a temperature of from about 450/sup 0/C to about 700/sup 0/C, for a time effective to convert, by reduction, discharged iron compounds consisting essentially of Fe and Fe(OH)/sub 2/ to charge iron compounds in the electrode and provide a recharged iron electrode; (E) an iron-air cell into which the recharged iron electrode provided in (D) is placed; (F) means to transport the recharged iron electrode provided in (D) to the iron-air cell of (E); and (G) electrical connection means attached to the iron-air cell of (E), providing the cell with capability of generating electrical energy.

  19. Iron-sulfur-based single molecular wires for enhancing charge transport in enzyme-based bioelectronic systems.

    PubMed

    Mahadevan, Aishwarya; Fernando, Teshan; Fernando, Sandun

    2016-04-15

    When redox enzymes are wired to electrodes outside a living cell (ex vivo), their ability to produce a sufficiently powerful electrical current diminishes significantly due to the thermodynamic and kinetic limitations associated with the wiring systems. Therefore, we are yet to harness the full potential of redox enzymes for the development of self-powering bioelectronics devices (such as sensors and fuel cells). Interestingly, nature uses iron-sulfur complexes ([Fe-S]), to circumvent these issues in vivo. Yet, we have not been able to utilize [Fe-S]-based chains ex vivo, primarily due to their instability in aqueous media. Here, a simple technique to attach iron (II) sulfide (FeS) to a gold surface in ethanol media and then complete the attachment of the enzyme in aqueous media is reported. Cyclic voltammetry and spectroscopy techniques confirmed the concatenation of FeS and glycerol-dehydrogenase/nicotinamide-adenine-dinucleotide (GlDH-NAD(+)) apoenzyme-coenzyme molecular wiring system on the base gold electrode. The resultant FeS-based enzyme electrode reached an open circuit voltage closer to its standard potential under a wide range of glycerol concentrations (0.001-1M). When probed under constant potential conditions, the FeS-based electrode was able to amplify current by over 10 fold as compared to electrodes fabricated with the conventional pyrroloquinoline quinone-based composite molecular wiring system. These improvements in current/voltage responses open up a wide range of possibilities for fabricating self-powering, bio-electronic devices. PMID:26657591

  20. mRNA regulation of cardiac iron transporters and ferritin subunits in a mouse model of iron overload.

    PubMed

    Brewer, Casey J; Wood, Ruth I; Wood, John C

    2014-12-01

    Iron cardiomyopathy is the leading cause of death in iron overload. Men have twice the mortality rate of women, though the cause is unknown. In hemojuvelin-knockout mice, a model of the disease, males load more cardiac iron than females. We postulated that sex differences in cardiac iron import cause differences in cardiac iron concentration. Reverse transcription polymerase chain reaction was used to measure mRNA of cardiac iron transporters in hemojuvelin-knockout mice. No sex differences were discovered among putative importers of nontransferrin-bound iron (L-type and T-type calcium channels, ZRT/IRT-like protein 14 zinc channels). Transferrin-bound iron transporters were also analyzed; these are controlled by the iron regulatory element/iron regulatory protein (IRE/IRP) system. There was a positive relationship between cardiac iron and ferroportin mRNA in both sexes, but it was significantly steeper in females (p < 0.05). Transferrin receptor 1 and divalent metal transporter 1 were more highly expressed in females than males (p < 0.01 and p < 0.0001, respectively), consistent with their lower cardiac iron levels, as predicted by IRE/IRP regulatory pathways. Light-chain ferritin showed a positive correlation with cardiac iron that was nearly identical in males and females (R(2) = 0.41, p < 0.01; R(2) = 0.56, p < 0.05, respectively), whereas heavy-chain ferritin was constitutively expressed in both sexes. This represents the first report of IRE/IRP regulatory pathways in the heart. Transcriptional regulation of ferroportin was suggested in both sexes, creating a potential mechanism for differential set points for iron export. Constitutive heavy-chain-ferritin expression suggests a logical limit to cardiac iron buffering capacity at levels known to produce heart failure in humans. PMID:25220979

  1. Ascorbate efflux as a new strategy for iron reduction and transport in plants.

    PubMed

    Grillet, Louis; Ouerdane, Laurent; Flis, Paulina; Hoang, Minh Thi Thanh; Isaure, Marie-Pierre; Lobinski, Ryszard; Curie, Catherine; Mari, Stéphane

    2014-01-31

    Iron (Fe) is essential for virtually all living organisms. The identification of the chemical forms of iron (the speciation) circulating in and between cells is crucial to further understand the mechanisms of iron delivery to its final targets. Here we analyzed how iron is transported to the seeds by the chemical identification of iron complexes that are delivered to embryos, followed by the biochemical characterization of the transport of these complexes by the embryo, using the pea (Pisum sativum) as a model species. We have found that iron circulates as ferric complexes with citrate and malate (Fe(III)3Cit2Mal2, Fe(III)3Cit3Mal1, Fe(III)Cit2). Because dicotyledonous plants only transport ferrous iron, we checked whether embryos were capable of reducing iron of these complexes. Indeed, embryos did express a constitutively high ferric reduction activity. Surprisingly, iron(III) reduction is not catalyzed by the expected membrane-bound ferric reductase. Instead, embryos efflux high amounts of ascorbate that chemically reduce iron(III) from citrate-malate complexes. In vitro transport experiments on isolated embryos using radiolabeled (55)Fe demonstrated that this ascorbate-mediated reduction is an obligatory step for the uptake of iron(II). Moreover, the ascorbate efflux activity was also measured in Arabidopsis embryos, suggesting that this new iron transport system may be generic to dicotyledonous plants. Finally, in embryos of the ascorbate-deficient mutants vtc2-4, vtc5-1, and vtc5-2, the reducing activity and the iron concentration were reduced significantly. Taken together, our results identified a new iron transport mechanism in plants that could play a major role to control iron loading in seeds. PMID:24347170

  2. Ascorbate Efflux as a New Strategy for Iron Reduction and Transport in Plants*

    PubMed Central

    Grillet, Louis; Ouerdane, Laurent; Flis, Paulina; Hoang, Minh Thi Thanh; Isaure, Marie-Pierre; Lobinski, Ryszard; Curie, Catherine; Mari, Stéphane

    2014-01-01

    Iron (Fe) is essential for virtually all living organisms. The identification of the chemical forms of iron (the speciation) circulating in and between cells is crucial to further understand the mechanisms of iron delivery to its final targets. Here we analyzed how iron is transported to the seeds by the chemical identification of iron complexes that are delivered to embryos, followed by the biochemical characterization of the transport of these complexes by the embryo, using the pea (Pisum sativum) as a model species. We have found that iron circulates as ferric complexes with citrate and malate (Fe(III)3Cit2Mal2, Fe(III)3Cit3Mal1, Fe(III)Cit2). Because dicotyledonous plants only transport ferrous iron, we checked whether embryos were capable of reducing iron of these complexes. Indeed, embryos did express a constitutively high ferric reduction activity. Surprisingly, iron(III) reduction is not catalyzed by the expected membrane-bound ferric reductase. Instead, embryos efflux high amounts of ascorbate that chemically reduce iron(III) from citrate-malate complexes. In vitro transport experiments on isolated embryos using radiolabeled 55Fe demonstrated that this ascorbate-mediated reduction is an obligatory step for the uptake of iron(II). Moreover, the ascorbate efflux activity was also measured in Arabidopsis embryos, suggesting that this new iron transport system may be generic to dicotyledonous plants. Finally, in embryos of the ascorbate-deficient mutants vtc2-4, vtc5-1, and vtc5-2, the reducing activity and the iron concentration were reduced significantly. Taken together, our results identified a new iron transport mechanism in plants that could play a major role to control iron loading in seeds. PMID:24347170

  3. Identification and transcriptional analysis of a Treponema pallidum operon encoding a putative ABC transport system, an iron-activated repressor protein homolog, and a glycolytic pathway enzyme homolog.

    PubMed

    Hardham, J M; Stamm, L V; Porcella, S F; Frye, J G; Barnes, N Y; Howell, J K; Mueller, S L; Radolf, J D; Weinstock, G M; Norris, S J

    1997-09-15

    We have characterized a 5.2-kilobase (kb) putative transport related operon (tro) locus of Treponema pallidum subsp. pallidum (Nichols strain) (Tp) encoding six proteins: TroA, TroB, TroC, TroD, TroR and Phosphoglycerate mutase (Pgm). Four of these gene products (TroA-TroD) are homologous to members of the ATP-Binding Cassette (ABC) superfamily of bacterial transport proteins. TroA (previously identified as Tromp1) has significant sequence similarity to a family of Gram-negative periplasmic substrate-binding proteins and to a family of streptococcal proteins that may have dual roles as substrate binding proteins and adhesins. TroB is homologous to the ATP-binding protein component, whereas TroC and TroD are related to the hydrophobic membrane protein components of ABC transport systems. TroR is similar to Gram-positive iron-activated repressor proteins (DesR, DtxR, IdeR, and SirR). The last open reading frame (ORF) of the tro operon encodes a protein that is highly homologous to the glycolytic pathway enzyme, Pgm. Primer extension results demonstrated that the tro operon is transcribed from a sigma 70-type promoter element. Northern analysis and reverse transcriptase-polymerase chain reactions provided evidence for the presence of a primary 1-kb troA transcript and a secondary, less abundant, troA-pgm transcript. The tro operon is flanked by a Holliday structure DNA helicase homolog (upstream) and two ORFs representing a purine nucleoside phosphorylase homolog and tpp15, a previously characterized gene encoding a membrane lipoprotein (downstream). The presence of a complex operon containing a putative ABC transport system and a DtxR homolog indicates a possible linkage between transport and gene regulation in Tp. PMID:9332349

  4. Effects of developmental iron deficiency and post-weaning iron repletion on the levels of iron transporter proteins in rats

    PubMed Central

    Oh, Sugyoung; Shin, Pill-kyung

    2015-01-01

    BACKGROUND/OBJECTIVES Iron deficiency in early life is associated with developmental problems, which may persist until later in life. The question of whether iron repletion after developmental iron deficiency could restore iron homeostasis is not well characterized. In the present study, we investigated the changes of iron transporters after iron depletion during the gestational-neonatal period and iron repletion during the post-weaning period. MATERIALS/METHODS Pregnant rats were provided iron-deficient (< 6 ppm Fe) or control (36 ppm Fe) diets from gestational day 2. At weaning, pups from iron-deficient dams were fed either iron-deficient (ID group) or control (IDR group) diets for 4 week. Pups from control dams were continued to be fed with the control diet throughout the study period (CON). RESULTS Compared to the CON, ID rats had significantly lower hemoglobin and hematocrits in the blood and significantly lower tissue iron in the liver and spleen. Hepatic hepcidin and BMP6 mRNA levels were also strongly down-regulated in the ID group. Developmental iron deficiency significantly increased iron transporters divalent metal transporter 1 (DMT1) and ferroportin (FPN) in the duodenum, but decreased DMT1 in the liver. Dietary iron repletion restored the levels of hemoglobin and hematocrit to a normal range, but the tissue iron levels and hepatic hepcidin mRNA levels were significantly lower than those in the CON group. Both FPN and DMT1 protein levels in the liver and in the duodenum were not different between the IDR and the CON. By contrast, DMT1 in the spleen was significantly lower in the IDR, compared to the CON. The splenic FPN was also decreased in the IDR more than in the CON, although the difference did not reach statistical significance. CONCLUSIONS Our findings demonstrate that iron transporter proteins in the duodenum, liver and spleen are differentially regulated during developmental iron deficiency. Also, post-weaning iron repletion efficiently

  5. 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

  6. Atypical iron storage in marine brown algae: a multidisciplinary study of iron transport and storage in Ectocarpus siliculosus

    PubMed Central

    Matzanke, Berthold F.; Küpper, Frithjof C.; Carrano, Carl J.

    2012-01-01

    Iron is an essential element for all living organisms due to its ubiquitous role in redox and other enzymes, especially in the context of respiration and photosynthesis. The iron uptake and storage systems of terrestrial/higher plants are now reasonably well understood, with two basic strategies for iron uptake being distinguished: strategy I plants use a mechanism involving induction of Fe(III)-chelate reductase (ferrireductase) and Fe(II) transporter proteins, while strategy II plants utilize high-affinity, iron-specific, binding compounds called phytosiderophores. In contrast, little is known about the corresponding systems in marine, plant-like lineages, particularly those of multicellular algae (seaweeds). Herein the first study of the iron uptake and storage mechanisms in the brown alga Ectocarpus siliculosus is reported. Genomic data suggest that Ectocarpus may use a strategy I approach. Short-term radio-iron uptake studies verified that iron is taken up by Ectocarpus in a time- and concentration-dependent manner consistent with an active transport process. Upon long-term exposure to 57Fe, two metabolites have been identified using a combination of Mössbauer and X-ray absorption spectroscopies. These include an iron–sulphur cluster accounting for ~26% of the total intracellular iron pool and a second component with spectra typical of a polymeric (Fe3+O6) system with parameters similar to the amorphous phosphorus-rich mineral core of bacterial and plant ferritins. This iron metabolite accounts for ~74% of the cellular iron pool and suggests that Ectocarpus contains a non-ferritin but mineral-based iron storage pool. PMID:22945940

  7. Chloroplast Iron Transport Proteins - Function and Impact on Plant Physiology.

    PubMed

    López-Millán, Ana F; Duy, Daniela; Philippar, Katrin

    2016-01-01

    Chloroplasts originated about three billion years ago by endosymbiosis of an ancestor of today's cyanobacteria with a mitochondria-containing host cell. During evolution chloroplasts of higher plants established as the site for photosynthesis and thus became the basis for all life dependent on oxygen and carbohydrate supply. To fulfill this task, plastid organelles are loaded with the transition metals iron, copper, and manganese, which due to their redox properties are essential for photosynthetic electron transport. In consequence, chloroplasts for example represent the iron-richest system in plant cells. However, improvement of oxygenic photosynthesis in turn required adaptation of metal transport and homeostasis since metal-catalyzed generation of reactive oxygen species (ROS) causes oxidative damage. This is most acute in chloroplasts, where radicals and transition metals are side by side and ROS-production is a usual feature of photosynthetic electron transport. Thus, on the one hand when bound by proteins, chloroplast-intrinsic metals are a prerequisite for photoautotrophic life, but on the other hand become toxic when present in their highly reactive, radical generating, free ionic forms. In consequence, transport, storage and cofactor-assembly of metal ions in plastids have to be tightly controlled and are crucial throughout plant growth and development. In the recent years, proteins for iron transport have been isolated from chloroplast envelope membranes. Here, we discuss their putative functions and impact on cellular metal homeostasis as well as photosynthetic performance and plant metabolism. We further consider the potential of proteomic analyses to identify new players in the field. PMID:27014281

  8. Quercetin inhibits intestinal iron absorption and ferroportin transporter expression in vivo and in vitro.

    PubMed

    Lesjak, Marija; Hoque, Rukshana; Balesaria, Sara; Skinner, Vernon; Debnam, Edward S; Srai, Surjit K S; Sharp, Paul A

    2014-01-01

    Balancing systemic iron levels within narrow limits is critical for maintaining human health. There are no known pathways to eliminate excess iron from the body and therefore iron homeostasis is maintained by modifying dietary absorption so that it matches daily obligatory losses. Several dietary factors can modify iron absorption. Polyphenols are plentiful in human diet and many compounds, including quercetin--the most abundant dietary polyphenol--are potent iron chelators. The aim of this study was to investigate the acute and longer-term effects of quercetin on intestinal iron metabolism. Acute exposure of rat duodenal mucosa to quercetin increased apical iron uptake but decreased subsequent basolateral iron efflux into the circulation. Quercetin binds iron between its 3-hydroxyl and 4-carbonyl groups and methylation of the 3-hydroxyl group negated both the increase in apical uptake and the inhibition of basolateral iron release, suggesting that the acute effects of quercetin on iron transport were due to iron chelation. In longer-term studies, rats were administered quercetin by a single gavage and iron transporter expression measured 18 h later. Duodenal FPN expression was decreased in quercetin-treated rats. This effect was recapitulated in Caco-2 cells exposed to quercetin for 18 h. Reporter assays in Caco-2 cells indicated that repression of FPN by quercetin was not a transcriptional event but might be mediated by miRNA interaction with the FPN 3'UTR. Our study highlights a novel mechanism for the regulation of iron bioavailability by dietary polyphenols. Potentially, diets rich in polyphenols might be beneficial for patients groups at risk of iron loading by limiting the rate of intestinal iron absorption. PMID:25058155

  9. Nonredundant Roles of Iron Acquisition Systems in Vibrio cholerae

    PubMed Central

    Peng, Eric D.; Wyckoff, Elizabeth E.; Mey, Alexandra R.; Fisher, Carolyn R.

    2015-01-01

    Vibrio cholerae, the causative agent of the severe diarrheal disease cholera, thrives in both marine environments and the human host. To do so, it must encode the tools necessary to acquire essential nutrients, including iron, under these vastly different conditions. A number of V. cholerae iron acquisition systems have been identified; however, the precise role of each system is not fully understood. To test the roles of individual systems, we generated a series of mutants in which only one of the four systems that support iron acquisition on unsupplemented LB agar, Feo, Fbp, Vct, and Vib, remains functional. Analysis of these mutants under different growth conditions showed that these systems are not redundant. The strain carrying only the ferrous iron transporter Feo grew well at acidic, but not alkaline, pH, whereas the ferric iron transporter Fbp promoted better growth at alkaline than at acidic pH. A strain defective in all four systems (null mutant) had a severe growth defect under aerobic conditions but accumulated iron and grew as well as the wild type in the absence of oxygen, suggesting the presence of an additional, unidentified iron transporter in V. cholerae. In support of this, the null mutant was only moderately attenuated in an infant mouse model of infection. While the null mutant used heme as an iron source in vitro, we demonstrate that heme is not available to V. cholerae in the infant mouse intestine. PMID:26644383

  10. AhNRAMP1 iron transporter is involved in iron acquisition in peanut.

    PubMed

    Xiong, Hongchun; Kobayashi, Takanori; Kakei, Yusuke; Senoura, Takeshi; Nakazono, Mikio; Takahashi, Hirokazu; Nakanishi, Hiromi; Shen, Hongyun; Duan, Penggen; Guo, Xiaotong; Nishizawa, Naoko K; Zuo, Yuanmei

    2012-07-01

    Peanut/maize intercropping is a sustainable and effective agroecosystem to alleviate iron-deficiency chlorosis. Using suppression subtractive hybridization from the roots of intercropped and monocropped peanut which show different iron nutrition levels, a peanut gene, AhNRAMP1, which belongs to divalent metal transporters of the natural resistance-associated macrophage protein (NRAMP) gene family was isolated. Yeast complementation assays suggested that AhNRAMP1 encodes a functional iron transporter. Moreover, the mRNA level of AhNRAMP1 was obviously induced by iron deficiency in both roots and leaves. Transient expression, laser microdissection, and in situ hybridization analyses revealed that AhNRAMP1 was mainly localized on the plasma membrane of the epidermis of peanut roots. Induced expression of AhNRAMP1 in tobacco conferred enhanced tolerance to iron deprivation. These results suggest that the AhNRAMP1 is possibly involved in iron acquisition in peanut plants. PMID:22611231

  11. Reduction of Mn-oxides by ferrous iron in a flow system: column experiment and reactive transport modeling

    NASA Astrophysics Data System (ADS)

    Postma, D.; Appelo, C. A. J.

    2000-04-01

    The reduction of Mn-oxide by Fe2+ was studied in column experiments, using a column filled with natural Mn-oxide coated sand. Analysis of the Mn-oxide indicated the presence of both Mn(III) and Mn(IV) in the Mn-oxide. The initial exchange capacity of the column was determined by displacement of adsorbed Ca2+ with Mg2+. Subsequently a FeCl2 solution was injected into the column causing the reduction of the Mn-oxide and the precipitation of Fe(OH)3. Finally the exchange capacity of the column containing newly formed Fe(OH)3 was determined by injection of a KBr solution. During injection of the FeCl2 solution into the column, an ion distribution pattern was observed in the effluent that suggests the formation of separate reaction fronts for Mn(III)-oxide and Mn(IV)-oxide travelling at different velocities through the column. At the proximal reaction front, Fe2+ reacts with MnO2 producing Fe(OH)3, Mn2+ and H+. The protons are transported downstream and cause the disproportionation of MnOOH at a separate reaction front. Between the two Mn reaction fronts, the dissolution and precipitation of Fe(OH)3 and Al(OH)3 act as proton buffers. Reactive transport modeling, using the code PHREEQC 2.0, was done to quantify and analyze the reaction controls and the coupling between transport and chemical processes. A model containing only mineral equilibria constraints for birnessite, manganite, gibbsite, and ferrihydrite, was able to explain the overall reaction pattern with the sequential appearance of Mn2+, Al3+, Fe3+, and Fe2+ in the column outlet solution. However, the initial breakthrough of a peak of Ca2+ and the observed pH buffering indicated that exchange processes were of importance as well. The amount of potential exchangers, such as birnessite and ferrihydrite, did vary in the course of the experiment. A model containing surface complexation coupled to varying concentrations of birnessite and ferrihydrite and a constant charge exchanger in addition to mineral equilibria

  12. A Systems Biology Approach to Iron Metabolism

    PubMed Central

    Chifman, J.; Laubenbacher, R.; Torti, S.V.

    2015-01-01

    Iron is critical to the survival of almost all living organisms. However, inappropriately low or high levels of iron are detrimental and contribute to a wide range of diseases. Recent advances in the study of iron metabolism have revealed multiple intricate pathways that are essential to the maintenance of iron homeostasis. Further, iron regulation involves processes at several scales, ranging from the subcellular to the organismal. This complexity makes a systems biology approach crucial, with its enabling technology of computational models based on a mathematical description of regulatory systems. Systems biology may represent a new strategy for understanding imbalances in iron metabolism and their underlying causes. PMID:25480643

  13. Multicomponent reactive transport in an in situ zero-valent iron cell

    SciTech Connect

    Yabusaki, Steven B. ); Cantrell, Kirk J. ); Sass, Bruce; Steefel, Carl

    2000-12-01

    Data collected from a field study of in situ zero-valent iron treatment for TCE were analyzed in the context of coupled transport and reaction processes. The focus of this analysis was to understand the behavior of chemical components, including contaminants, in groundwater transported through the iron cell of a pilot-scale funnel and gate treatment system. A multicomponent reactive transport simulator was used to simultaneously model mobile and nonmobile components undergoing equilibrium and kinetic reactions including TCE degradation, parallel iron dissolution reactions, precipitation of secondary minerals, and complexation reactions. The resulting mechanistic model of coupled processes reproduced solution chemistry behavior observed in the iron cell with a minimum of calibration. These observations included the destruction of TCE and cis-1,2-DCE; increases in pH and hydrocarbons; and decreases in EH, alkalinity, dissolved O2 and CO2, and major ions (i.e., Ca, Mg, Cl, sulfate, nitrate). Mineral precipitation in the iron zone was critical to correctly predicting these behaviors. The dominant precipitation products were ferrous hydroxide, siderite, aragonite, brucite, and iron sulfide. In the first few centimeters of the reactive iron cell, these precipitation products are predicted to account for a 3% increase in mineral volume per year, which could have implications for the longevity of favorable barrier hydraulics and reactivity. The inclusion of transport was key to understanding the interplay between rates of transport and rates of reaction in the field.

  14. Ferritin polarization and iron transport across monolayer epithelial barriers in mammals

    PubMed Central

    Meyron-Holtz, Esther G.; Cohen, Lyora A.; Fahoum, Lulu; Haimovich, Yael; Lifshitz, Lena; Magid-Gold, Inbar; Stuemler, Tanja; Truman-Rosentsvit, Marianna

    2014-01-01

    Epithelial barriers are found in many tissues such as the intestine, kidney and brain where they separate the external environment from the body or a specific compartment from its periphery. Due to the tight junctions that connect epithelial barrier-cells (EBCs), the transport of compounds takes place nearly exclusively across the apical or basolateral membrane, the cell-body and the opposite membrane of the polarized EBC, and is regulated on numerous levels including barrier-specific adapted trafficking-machineries. Iron is an essential element but toxic at excess. Therefore, all iron-requiring organisms tightly regulate iron concentrations on systemic and cellular levels. In contrast to most cell types that control just their own iron homeostasis, EBCs also regulate homeostasis of the compartment they enclose or the body as a whole. Iron is transported across EBCs by specialized transporters such as the transferrin receptor and ferroportin. Recently, the iron storage protein ferritin was also attributed a role in the regulation of systemic iron homeostasis and we gathered evidence from the literature and original data that ferritin is polarized in EBC, suggesting also a role for ferritin in iron trafficking across EBCs. PMID:25202274

  15. Shigella Iron Acquisition Systems and their Regulation

    PubMed Central

    Wei, Yahan; Murphy, Erin R.

    2016-01-01

    Survival of Shigella within the host is strictly dependent on the ability of the pathogen to acquire essential nutrients, such as iron. As an innate immune defense against invading pathogens, the level of bio-available iron within the human host is maintained at exceeding low levels, by sequestration of the element within heme and other host iron-binding compounds. In response to sequestration mediated iron limitation, Shigella produce multiple iron-uptake systems that each function to facilitate the utilization of a specific host-associated source of nutrient iron. As a mechanism to balance the essential need for iron and the toxicity of the element when in excess, the production of bacterial iron acquisition systems is tightly regulated by a variety of molecular mechanisms. This review summarizes the current state of knowledge on the iron-uptake systems produced by Shigella species, their distribution within the genus, and the molecular mechanisms that regulate their production. PMID:26904516

  16. Hydrogen transport in iron and steel

    NASA Technical Reports Server (NTRS)

    Louthan, M. R., Jr.; Derrick, R. G.; Donovan, J. A.; Caskey, G. R., Jr.

    1976-01-01

    The permeabilities of protium, deuterium, and tritium in foil specimens of Marz grade iron, 4130 steel, Armco iron, HP-9-4-20, and T-1 steels were studied at hydrogen pressures between 0.02 and 0.5 MPa over the temperature range 260-700 K. The permeability was measured by a pressure-rise method, deuterium counting with a detector, and radioactivity counting. Good agreement is found between the measurement techniques used. It is shown that the permeabilities of protium, deuterium, and tritium in iron and T-1 steel at temperatures as low as 260 K are in good agreement with the equation proposed by Gonzalez (1967). However, the permeabilities of HP-9-4-20 and 4130 steel to hydrogen are typically lower than predicted. The isotope effect on hydrogen permeability of HP-9-4-20, 4130 and T-1 steels, and high-purity iron can be estimated by an inverse square root of mass correction.

  17. Thermal transport properties of grey cast irons

    SciTech Connect

    Hecht, R.L.; Dinwiddie, R.B.; Porter, W.D.; Wang, Hsin

    1996-10-01

    Thermal diffusivity and thermal conductivity of grey cast iron have been measured as a function of graphite flake morphology, chemical composition, and position in a finished brake rotor. Cast iron samples used for this investigation were cut from ``step block`` castings designed to produce iron with different graphite flake morphologies resulting from different cooling rates. Samples were also machined from prototype alloys and from production brake rotors representing a variation in foundry practice. Thermal diffusivity was measured at room and elevated temperatures via the flash technique. Heat capacity of selected samples was measured with differential scanning calorimetry, and these results were used to calculate the thermal conductivity. Microstructure of the various cast iron samples was quantified by standard metallography and image analysis, and the chemical compositions were determined by optical emission spectroscopy.

  18. Pivotal Role of Iron in the Regulation of Cyanobacterial Electron Transport.

    PubMed

    González, A; Sevilla, E; Bes, M T; Peleato, M L; Fillat, M F

    2016-01-01

    Iron-containing metalloproteins are the main cornerstones for efficient electron transport in biological systems. The abundance and diversity of iron-dependent proteins in cyanobacteria makes those organisms highly dependent of this micronutrient. To cope with iron imbalance, cyanobacteria have developed a survey of adaptation strategies that are strongly related to the regulation of photosynthesis, nitrogen metabolism and other central electron transfer pathways. Furthermore, either in its ferrous form or as a component of the haem group, iron plays a crucial role as regulatory signalling molecule that directly or indirectly modulates the composition and efficiency of cyanobacterial redox reactions. We present here the major mechanism used by cyanobacteria to couple iron homeostasis to the regulation of electron transport, making special emphasis in processes specific in those organisms. PMID:27134024

  19. Ceruloplasmin-ferroportin system of iron traffic in vertebrates

    PubMed Central

    Musci, Giovanni; Polticelli, Fabio; Bonaccorsi di Patti, Maria Carmela

    2014-01-01

    Safe trafficking of iron across the cell membrane is a delicate process that requires specific protein carriers. While many proteins involved in iron uptake by cells are known, only one cellular iron export protein has been identified in mammals: ferroportin (SLC40A1). Ceruloplasmin is a multicopper enzyme endowed with ferroxidase activity that is found as a soluble isoform in plasma or as a membrane-associated isoform in specific cell types. According to the currently accepted view, ferrous iron transported out of the cell by ferroportin would be safely oxidized by ceruloplasmin to facilitate loading on transferrin. Therefore, the ceruloplasmin-ferroportin system represents the main pathway for cellular iron egress and it is responsible for physiological regulation of cellular iron levels. The most recent findings regarding the structural and functional features of ceruloplasmin and ferroportin and their relationship will be described in this review. PMID:24921009

  20. Systemic iron overload associated with Welder's siderosis.

    PubMed

    Patel, Rajesh R; Yi, Eunhee S; Ryu, Jay H

    2009-01-01

    Welding involves exposure to fumes, gases, radiation, electricity, noise, and heat. Herein, we describe 2 welders presenting with lung infiltrates and elevated liver enzyme levels. Both of these patients had pulmonary siderosis ("welder's lung") on lung biopsy along with evidence of systemic iron overload. Evaluation for genetic hemochromatosis and other known causes of iron overload was unrevealing. Welding with chronic inhalation of iron particles maybe an under-recognized source of systemic iron overload. PMID:18941405

  1. Iron production maintenance effectiveness system

    SciTech Connect

    Augstman, J.J.

    1996-12-31

    In 1989, an internal study in the Coke and Iron Maintenance Department identified the opportunities available to increase production, by decreasing unscheduled maintenance delays from 4.6%. A five year front loaded plan was developed, and presented to the company president. The plan required an initial investment of $1.4 million and a conservative break-even point was calculated to be 2.5 years. Due to budget restraints, it would have to be self-funded, i.e., generate additional production or savings, to pay for the program. The program began in 1991 at number 2 coke plant and the blast furnaces. This paper will describe the Iron Production Maintenance Effectiveness System (ME), which began with the mechanical and pipefitting trades.

  2. Monoubiquitin-dependent endocytosis of the iron-regulated transporter 1 (IRT1) transporter controls iron uptake in plants.

    PubMed

    Barberon, Marie; Zelazny, Enric; Robert, Stéphanie; Conéjéro, Geneviève; Curie, Cathy; Friml, Jìrí; Vert, Grégory

    2011-08-01

    Plants take up iron from the soil using the iron-regulated transporter 1 (IRT1) high-affinity iron transporter at the root surface. Sophisticated regulatory mechanisms allow plants to tightly control the levels of IRT1, ensuring optimal absorption of essential but toxic iron. Here, we demonstrate that overexpression of Arabidopsis thaliana IRT1 leads to constitutive IRT1 protein accumulation, metal overload, and oxidative stress. IRT1 is unexpectedly found in trans-Golgi network/early endosomes of root hair cells, and its levels and localization are unaffected by iron nutrition. Using pharmacological approaches, we show that IRT1 cycles to the plasma membrane to perform iron and metal uptake at the cell surface and is sent to the vacuole for proper turnover. We also prove that IRT1 is monoubiquitinated on several cytosol-exposed residues in vivo and that mutation of two putative monoubiquitination target residues in IRT1 triggers stabilization at the plasma membrane and leads to extreme lethality. Together, these data suggest a model in which monoubiquitin-dependent internalization/sorting and turnover keep the plasma membrane pool of IRT1 low to ensure proper iron uptake and to prevent metal toxicity. More generally, our work demonstrates the existence of monoubiquitin-dependent trafficking to lytic vacuoles in plants and points to proteasome-independent turnover of plasma membrane proteins. PMID:21628566

  3. Controls on radium transport by adsorption to iron minerals

    NASA Astrophysics Data System (ADS)

    Chen, M.; Wang, T.; Kocar, B. D.

    2015-12-01

    Radium is a naturally occurring radioactive metal found in many subsurface environments. Radium isotopes are generated by uranium and thorium decay, and are particularly abundant within groundwaters where minimal porewater flux leads to accumulation. These isotopes are used as natural tracers for estimating submarine groundwater discharge (SGD) [1], allowing for large scale estimation of GW fluxes into and out of the ocean [2]. They also represent a substantial hazard in wastewater produced after hydraulic fracturing for natural gas extraction [3], resulting in a significant risk of environmental release to surface and near-surface waters, and increased cost for water treatment or disposal. Adsorption to mineral surfaces represents a dominant pathway of radium retention in subsurface environments. For SGD studies, adsorption processes impact estimates of GW fluxes, while in hydraulic fracturing, radium adsorption to aquifer solids mediates wastewater radium activities. Analysis of past sorption studies revealed large variability in partition coefficients [4], while examination of radium adsorption kinetics and surface complexation have only recently started [5]. Accordingly, we present the results of sorption and column experiments of radium with a suite of iron minerals representative of those found within deep saline and near-surface (freshwater) aquifers, and evaluate impacts of varying salinity solutions through artificial waters. Further, we explore the impacts of pyrite oxidation and ferrihydrite transformation to other iron-bearing secondary minerals on the transport and retention of radium. These results will provide critical information on the mineralogical controls on radium retention in subsurface environments, and will therefore improve predictions of radium groundwater transport in natural and contaminated systems. [1] Charette, M.A., Buesseler, K.O. & Andrews, J.E., Limnol. Oceanogr. (2001). [2] Moore, W.S., Ann. Rev. Mar. Sci. (2010). [3] Vengosh, A

  4. Transgenic petunia with the iron(III)-phytosiderophore transporter gene acquires tolerance to iron deficiency in alkaline environments.

    PubMed

    Murata, Yoshiko; Itoh, Yoshiyuki; Iwashita, Takashi; Namba, Kosuke

    2015-01-01

    Iron is an essential nutrient for all plants. However, terrestrial plants often suffer from iron deficiency in alkaline soil due to its extremely low solubility. Alkaline soil accounts for about 30% of all cultivated ground in the world. Plants have evolved two distinct strategies, I and II, for iron uptake from the soil. Dicots and non-graminaceous monocots use Strategy I, which is primarily based on the reduction of iron(III) to iron(II) and the uptake of iron(II) by the iron-regulated transporter, IRT1. In contrast, graminaceous plants use Strategy II to efficiently acquire insoluble iron(III). Strategy II comprises the synthesis and secretion of iron-chelating phytosiderophores, such as mugineic acids and the Yellow Stripe 1 transporter proteins of the iron(III)-phytosiderophore complex. Barley, which exhibits the highest tolerance to iron deficiency in alkaline soil among graminaceous plants, utilizes mugineic acids and the specific iron(III)-mugineic acids transporter, HvYS1. In this study, we established the transgenic plant Petunia hybrida, which originally had only Strategy I, by introducing the HvYS1 transporter gene derived from barley. When the transgenic plants were grown hydroponically in media containing the iron(III)-2'-deoxymugineic acid complex, free 2'-deoxymugineic acid and its iron(III) complex were detected in the root extract of the transgenic plant by electrospray ionization-Fourier transform-ion cyclotron resonance mass spectrometry. The growth of the transgenic petunia was significantly better than that of the control host in alkaline conditions. Consequently, the transgenic plant acquired a significantly enhanced tolerance to alkaline hydroponic media in the presence of the iron(III)-2'-deoxymugineic acid complex. Furthermore, the flower color of the transgenic plant deepened. The results showed that iron-phytosiderophore complexes and their transporters can potentially be utilized to overcome the worldwide iron uptake problems to diverse

  5. A vacuolar iron-transporter homologue acts as a detoxifier in Plasmodium

    PubMed Central

    Slavic, Ksenija; Krishna, Sanjeev; Lahree, Aparajita; Bouyer, Guillaume; Hanson, Kirsten K.; Vera, Iset; Pittman, Jon K.; Staines, Henry M.; Mota, Maria M.

    2016-01-01

    Iron is an essential micronutrient but is also highly toxic. In yeast and plant cells, a key detoxifying mechanism involves iron sequestration into intracellular storage compartments, mediated by members of the vacuolar iron-transporter (VIT) family of proteins. Here we study the VIT homologue from the malaria parasites Plasmodium falciparum (PfVIT) and Plasmodium berghei (PbVIT). PfVIT-mediated iron transport in a yeast heterologous expression system is saturable (Km∼14.7 μM), and selective for Fe2+ over other divalent cations. PbVIT-deficient P. berghei lines (Pbvit−) show a reduction in parasite load in both liver and blood stages of infection in mice. Moreover, Pbvit− parasites have higher levels of labile iron in blood stages and are more sensitive to increased iron levels in liver stages, when compared with wild-type parasites. Our data are consistent with Plasmodium VITs playing a major role in iron detoxification and, thus, normal development of malaria parasites in their mammalian host. PMID:26786069

  6. A vacuolar iron-transporter homologue acts as a detoxifier in Plasmodium.

    PubMed

    Slavic, Ksenija; Krishna, Sanjeev; Lahree, Aparajita; Bouyer, Guillaume; Hanson, Kirsten K; Vera, Iset; Pittman, Jon K; Staines, Henry M; Mota, Maria M

    2016-01-01

    Iron is an essential micronutrient but is also highly toxic. In yeast and plant cells, a key detoxifying mechanism involves iron sequestration into intracellular storage compartments, mediated by members of the vacuolar iron-transporter (VIT) family of proteins. Here we study the VIT homologue from the malaria parasites Plasmodium falciparum (PfVIT) and Plasmodium berghei (PbVIT). PfVIT-mediated iron transport in a yeast heterologous expression system is saturable (Km ∼ 14.7 μM), and selective for Fe(2+) over other divalent cations. PbVIT-deficient P. berghei lines (Pbvit(-)) show a reduction in parasite load in both liver and blood stages of infection in mice. Moreover, Pbvit(-) parasites have higher levels of labile iron in blood stages and are more sensitive to increased iron levels in liver stages, when compared with wild-type parasites. Our data are consistent with Plasmodium VITs playing a major role in iron detoxification and, thus, normal development of malaria parasites in their mammalian host. PMID:26786069

  7. Phosphorus: Riverine system transport

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The transport and transformation of phosphorus (P) in riverine systems fundamentally affects the outcome of watershed mitigation strategies aimed at curbing downstream eutrophication. Phosphorus transport and transformations in streams and rivers are mediated by physical (sediment deposition and res...

  8. Transportation System Requirements Document

    SciTech Connect

    Not Available

    1993-09-01

    This Transportation System Requirements Document (Trans-SRD) describes the functions to be performed by and the technical requirements for the Transportation System to transport spent nuclear fuel (SNF) and high-level radioactive waste (HLW) from Purchaser and Producer sites to a Civilian Radioactive Waste Management System (CRWMS) site, and between CRWMS sites. The purpose of this document is to define the system-level requirements for Transportation consistent with the CRWMS Requirement Document (CRD). These requirements include design and operations requirements to the extent they impact on the development of the physical segments of Transportation. The document also presents an overall description of Transportation, its functions, its segments, and the requirements allocated to the segments and the system-level interfaces with Transportation. The interface identification and description are published in the CRWMS Interface Specification.

  9. Relationship between gene expression of duodenal iron transporters and iron stores in hemochromatosis subjects.

    PubMed

    Nelson, James E; Mugford, Virginia R; Kilcourse, Ellen; Wang, Richard S; Kowdley, Kris V

    2010-01-01

    To test the hypothesis that differences in duodenal iron absorption may explain the variable phenotypic expression among HFE C282Y homozygotes, we have compared relative gene expression of duodenal iron transporters among C282Y homozygotes [hereditary hemochromatosis (HH)] with and without iron overload. Duodenal biopsy samples were analyzed using real-time PCR for expression of DMT1, FPN1, DCYTB, and HEPH relative to GAPDH from 23 C282Y homozygotes, including 5 "nonexpressors" (serum ferritin < upper limit of normal and absence of phenotypic features of hemochromatosis) and 18 "expressors." Four subjects of wild type for HFE mutations without iron overload or liver disease served as controls. There was a significant difference in expression of DMT1 (P = 0.03) and DMT1(IRE) (P = 0.0013) but not FPN1, DCYTB, or HEPH between groups. Expression of DMT1(IRE) was increased among HH subjects after phlebotomy compared with untreated (P = 0.006) and nonexpressor groups (P = 0.026). A positive relationship was observed among all HH subjects regardless of phenotype or treatment status between relative expression of FPN1 and DMT1 (r = 0.5854, P = 0.0021), FPN1, and DCYTB (r = 0.5554, P = 0.0040), FPN1 and HEPH (r = 0.5100, P = 0.0092), and DCYTB and HEPH (r = 0.5400, P = 0.0053). In summary, phlebotomy is associated with upregulation of DMT1(IRE) expression in HH subjects. HFE C282Y homozygotes without phenotypic expression do not have significantly decreased duodenal gene expression of iron transport genes compared with HH subjects with iron overload. There is coordinated regulation between duodenal expression of FPN1 and DMT1, FPN1 and DCYTB, and FPN1 and HEPH and also DCYTB and HEPH in HH subjects regardless of phenotype. PMID:19892936

  10. Relationship between gene expression of duodenal iron transporters and iron stores in hemochromatosis subjects

    PubMed Central

    Nelson, James E.; Mugford, Virginia R.; Kilcourse, Ellen; Wang, Richard S.

    2010-01-01

    To test the hypothesis that differences in duodenal iron absorption may explain the variable phenotypic expression among HFE C282Y homozygotes, we have compared relative gene expression of duodenal iron transporters among C282Y homozygotes [hereditary hemochromatosis (HH)] with and without iron overload. Duodenal biopsy samples were analyzed using real-time PCR for expression of DMT1, FPN1, DCYTB, and HEPH relative to GAPDH from 23 C282Y homozygotes, including 5 “nonexpressors” (serum ferritin < upper limit of normal and absence of phenotypic features of hemochromatosis) and 18 “expressors.” Four subjects of wild type for HFE mutations without iron overload or liver disease served as controls. There was a significant difference in expression of DMT1 (P = 0.03) and DMT1(IRE) (P = 0.0013) but not FPN1, DCYTB, or HEPH between groups. Expression of DMT1(IRE) was increased among HH subjects after phlebotomy compared with untreated (P = 0.006) and nonexpressor groups (P = 0.026). A positive relationship was observed among all HH subjects regardless of phenotype or treatment status between relative expression of FPN1 and DMT1 (r = 0.5854, P = 0.0021), FPN1, and DCYTB (r = 0.5554, P = 0.0040), FPN1 and HEPH (r = 0.5100, P = 0.0092), and DCYTB and HEPH (r = 0.5400, P = 0.0053). In summary, phlebotomy is associated with upregulation of DMT1(IRE) expression in HH subjects. HFE C282Y homozygotes without phenotypic expression do not have significantly decreased duodenal gene expression of iron transport genes compared with HH subjects with iron overload. There is coordinated regulation between duodenal expression of FPN1 and DMT1, FPN1 and DCYTB, and FPN1 and HEPH and also DCYTB and HEPH in HH subjects regardless of phenotype. PMID:19892936

  11. Payload transportation system study

    NASA Technical Reports Server (NTRS)

    1976-01-01

    A standard size set of shuttle payload transportation equipment was defined that will substantially reduce the cost of payload transportation and accommodate a wide range of payloads with minimum impact on payload design. The system was designed to accommodate payload shipments between the level 4 payload integration sites and the launch site during the calendar years 1979-1982. In addition to defining transportation multi-use mission support equipment (T-MMSE) the mode of travel, prime movers, and ancillary equipment required in the transportation process were also considered. Consistent with the STS goals of low cost and the use of standardized interfaces, the transportation system was designed to commercial grade standards and uses the payload flight mounting interfaces for transportation. The technical, cost, and programmatic data required to permit selection of a baseline system of MMSE for intersite movement of shuttle payloads were developed.

  12. Vacuolar-Iron-Transporter1-Like proteins mediate iron homeostasis in Arabidopsis.

    PubMed

    Gollhofer, Julia; Timofeev, Roman; Lan, Ping; Schmidt, Wolfgang; Buckhout, Thomas J

    2014-01-01

    Iron deficiency is a nutritional problem in plants and reduces crop productivity, quality and yield. With the goal of improving the iron (Fe) storage properties of plants, we have investigated the function of three Arabidopsis proteins with homology to Vacuolar Iron Transporter1 (AtVIT1). Heterologous expression of Vacuolar Iron Transporter-Like1 (AtVTL1; At1g21140), AtVTL2 (At1g76800) or AtVTL5 (At3g25190) in the yeast vacuolar Fe transport mutant, Δccc1, restored growth in the presence of 4 mM Fe. Isolated vacuoles from yeast expressing either of the VTL genes in the Δccc1 background had a three- to four-fold increase in Fe concentration compared to vacuoles isolated from the untransformed mutant. Transiently expressed GFP-tagged AtVTL1 was localized exclusively and AtVTL2 was localized primarily to the vacuolar membrane of onion epidermis cells. Seedling root growth of the Arabidopsis nramp3/nramp4 and vit1-1 mutants was decreased compared to the wild type when seedlings were grown under Fe deficiency. When expressed under the 35S promoter in the nramp3/nramp4 or vit1-1 backgrounds, AtVTL1, AtVTL2 or AtVTL5 restored root growth in both mutants. The seed Fe concentration in the nramp3/nramp4 mutant overexpressing AtVTL1, AtVTL2 or AtVTL5 was between 50 and 60% higher than in non-transformed double mutants or wild-type plants. We conclude that the VTL proteins catalyze Fe transport into vacuoles and thus contribute to the regulation of Fe homeostasis in planta. PMID:25360591

  13. The transferrin-iron import system from pathogenic Neisseria species.

    PubMed

    Noinaj, Nicholas; Buchanan, Susan K; Cornelissen, Cynthia Nau

    2012-10-01

    Two pathogenic species within the genus Neisseria cause the diseases gonorrhoea and meningitis. While vaccines are available to protect against four N. meningitidis serogroups, there is currently no commercial vaccine to protect against serogroup B or against N. gonorrhoeae. Moreover, the available vaccines have significant limitations and with antibiotic resistance becoming an alarming issue, the search for effective vaccine targets to elicit long-lasting protection against Neisseria species is becoming more urgent. One strategy for vaccine development has targeted the neisserial iron import systems. Without iron, the Neisseriae cannot survive and, therefore, these iron import systems tend to be relatively well conserved and are promising vaccine targets, having the potential to offer broad protection against both gonococcal and meningococcal infections. These efforts have been boosted by recent reports of the crystal structures of the neisserial receptor proteins TbpA and TbpB, each solved in complex with human transferrin, an iron binding protein normally responsible for delivering iron to human cells. Here, we review the recent structural reports and put them into perspective with available functional studies in order to derive the mechanism(s) for how the pathogenic Neisseriae are able to hijack human iron transport systems for their own survival and pathogenesis. PMID:22957710

  14. Iron-binding activity of FutA1 subunit of an ABC-type iron transporter in the cyanobacterium Synechocystis sp. Strain PCC 6803.

    PubMed

    Katoh, H; Hagino, N; Ogawa, T

    2001-08-01

    The futA1 (slr1295) and futA2 (slr0513) genes encode periplasmic binding proteins of an ATP-binding cassette (ABC)-type iron transporter in Synechocystis sp. PCC 6803. FutA1 was expressed in Escherichia coli as a GST-tagged recombinant protein (rFutA1). Solution containing purified rFutA1 and ferric chloride showed an absorption spectrum with a peak at 453 nm. The absorbance at this wavelength rose linearly as the amount of iron bound to rFutA1 increased to reach a plateau when the molar ratio of iron to rFutA1 became unity. The association constant of rFutA1 for iron in vitro was about 1 x 10(19). These results demonstrate that the FutA1 binds the ferric ion with high affinity. The activity of iron uptake in the Delta futA1 and Delta futA2 mutants was 37 and 84%, respectively, of that in the wild-type and the activity was less than 5% in the Delta futA1/Delta futA2 double mutant, suggesting their redundant role for binding iron. High concentrations of citrate inhibited ferric iron uptake. These results suggest that the natural iron source transported by the Fut system is not ferric citrate. PMID:11522907

  15. *Iron accumulation in bronchial epithelial cells is dependent on concurrent sodium transport

    EPA Science Inventory

    Airway epithelial cells prevent damaging effects of extracellular iron by taking up the metal and sequestering it within intracellular ferritin. Epithelial iron transport is associated with transcellular movement of other cations including changes in the expression or activity of...

  16. Influence of hydrogen chemisorption kinetics on the interpretation of hydrogen transport through iron membranes

    NASA Technical Reports Server (NTRS)

    Shanabarger, M. R.; Taslami, A.; Nelson, H. G.

    1981-01-01

    The influence of a specific surface reaction on the transport of gas-phase hydrogen through iron membranes has been investigated on the basis of model calculations. The surface reaction involves an adsorbed molecular hydrogen precursor between the gas phase and the dissociated chemisorbed state. The calculations demonstrate that the surface reaction for the H2/Fe system makes significant contributions to the time delay associated with the transient hydrogen transport through iron membranes, even under conditions where the steady-state hydrogen transport is independent of the surface reaction. These contributions to the time delay are interpreted in terms of an effective diffusivity, which is a function of the pressure on the entrance side and the thickness of the membrane.

  17. Space Transportation systems overview

    NASA Technical Reports Server (NTRS)

    Lee, C. M.

    1979-01-01

    Planning for the operations phase of the Space Transportation system is reviewed. Attention is given to mission profile (typical), applications, manifesting rationale, the Operational Flight Test manifest, the operations manifest, pricing policy, and potential applications of the STS.

  18. Smart vehicular transportation systems

    SciTech Connect

    Little, C.Q.; Wilson, C.W.

    1997-05-01

    This work builds upon established Sandia intelligent systems technology to develop a unique approach for the integration of intelligent system control into the US Highway and urban transportation systems. The Sandia developed concept of the COPILOT controller integrates a human driver with computer control to increase human performance while reducing reliance on detailed driver attention. This research extends Sandia expertise in sensor based, real-time control of robotics systems to high speed transportation systems. Knowledge in the form of maps and performance characteristics of vehicles provides the automatic decision making intelligence needed to plan optimum routes, maintain safe driving speeds and distances, avoid collisions, and conserve fuel.

  19. The metal transporter ZIP13 supplies iron into the secretory pathway in Drosophila melanogaster

    PubMed Central

    Xiao, Guiran; Wan, Zhihui; Fan, Qiangwang; Tang, Xiaona; Zhou, Bing

    2014-01-01

    The intracellular iron transfer process is not well understood, and the identity of the iron transporter responsible for iron delivery to the secretory compartments remains elusive. In this study, we show Drosophila ZIP13 (Slc39a13), a presumed zinc importer, fulfills the iron effluxing role. Interfering with dZIP13 expression causes iron-rescuable iron absorption defect, simultaneous iron increase in the cytosol and decrease in the secretory compartments, failure of ferritin iron loading, and abnormal collagen secretion. dZIP13 expression in E. coli confers upon the host iron-dependent growth and iron resistance. Importantly, time-coursed transport assays using an iron isotope indicated a potent iron exporting activity of dZIP13. The identification of dZIP13 as an iron transporter suggests that the spondylocheiro dysplastic form of Ehlers–Danlos syndrome, in which hZIP13 is defective, is likely due to a failure of iron delivery to the secretory compartments. Our results also broaden our knowledge of the scope of defects from iron dyshomeostasis. DOI: http://dx.doi.org/10.7554/eLife.03191.001

  20. The role of the synergistic phosphate anion in iron transport by the periplasmic iron-binding protein from Haemophilus influenzae

    PubMed Central

    Khan, Ali G.; Shouldice, Stephen R.; Tari, Leslie W.; Schryvers, Anthony B.

    2006-01-01

    The acquisition of iron from transferrin by Gram-negative bacterial pathogens is dependent on a periplasmic ferric-ion-binding protein, FbpA. FbpA shuttles iron from the outer membrane to an inner membrane transport complex. A bound phosphate anion completes the iron co-ordination shell of FbpA and kinetic studies demonstrate that the anion plays a critical role in iron binding and release in vitro. The present study was initiated to directly address the hypothesis that the synergistic anion is required for transport of iron in intact cells. A series of site-directed mutants in the anion-binding amino acids of the Haemophilus influenzae FbpA (Gln-58, Asn-175 and Asn-193) were prepared to provide proteins defective in binding of the phosphate anion. Crystal structures of various mutants have revealed that alteration of the C-terminal domain ligands (Asn-175 or Asn-193) but not the N-terminal domain ligand (Gln-58) abrogated binding of the phosphate anion. The mutant proteins were introduced into H. influenzae to evaluate their ability to mediate iron transport. All of the single site-directed mutants (Q58L, N175L and N193L) were capable of mediating iron acquisition from transferrin and from limiting concentrations of ferric citrate. The results suggest that the transport of iron by FbpA is not dependent on binding of phosphate in the synergistic anion-binding site. PMID:17147516

  1. Calcium channel blockers ameliorate iron overload-associated hepatic fibrosis by altering iron transport and stellate cell apoptosis.

    PubMed

    Zhang, Ying; Zhao, Xin; Chang, Yanzhong; Zhang, Yuanyuan; Chu, Xi; Zhang, Xuan; Liu, Zhenyi; Guo, Hui; Wang, Na; Gao, Yonggang; Zhang, Jianping; Chu, Li

    2016-06-15

    Liver fibrosis is the principal cause of morbidity and mortality in patients with iron overload. Calcium channel blockers (CCBs) can antagonize divalent cation entry into renal and myocardial cells and inhibit fibrogenic gene expression. We investigated the potential of CCBs to resolve iron overload-associated hepatic fibrosis. Kunming mice were assigned to nine groups (n=8 per group): control, iron overload, deferoxamine, high and low dose verapamil, high and low dose nimodipine, and high and low dose diltiazem. Iron deposition and hepatic fibrosis were measured in mouse livers. Expression levels of molecules associated with transmembrane iron transport were determined by molecular biology approaches. In vitro HSC-T6 cells were randomized into nine groups (the same groups as the mice). Changes in proliferation, apoptosis, and metalloproteinase expression in cells were detected to assess the anti-fibrotic effects of CCBs during iron overload conditions. We found that CCBs reduced hepatic iron content, intracellular iron deposition, the number of hepatic fibrotic areas, collagen expression levels, and hydroxyproline content. CCBs rescued abnormal expression of α1C protein in L-type voltage-dependent calcium channel (LVDCC) and down-regulated divalent metal transporter-1 (DMT-1) expression in mouse livers. In iron-overloaded HSC-T6 cells, CCBs reduced iron deposition, inhibited proliferation, induced apoptosis, and elevated expression of matrix metalloproteinase-13 (MMP-13) and tissue inhibitor of metalloproteinase-1 (TIMP-1). CCBs are potential therapeutic agents that can be used to address hepatic fibrosis during iron overload. They resolve hepatic fibrosis probably correlated with regulating transmembrane iron transport and inhibiting HSC growth. PMID:27095094

  2. Local Pathways in Coherent Electron Transport through Iron Porphyrin Complexes: A Challenge for First-Principles Transport Calculations

    SciTech Connect

    Herrmann, C.; Solomon, G.C.; Ratner, Mark A.

    2010-12-09

    We investigate the coherent electron transport properties of a selection of iron porphyrin complexes in their low-spin and high-spin states, binding the system to metallic electrodes with three different substitution patterns. We use a study of the local transmission through the complexes and their molecular orbitals to show the role of the various components of the molecular structure in mediating electron transport. While there are energies where the metal center and the axial ligands participate in transport, in the off-resonant energy range, these components simply form a scaffold, and the transport is dominated by transmission through the porphyrin macrocyle alone. This is still true when going from the low-spin to the high-spin state, except that now, an additional iron-centered MO contributes to transport in the formerly off-resonant region. It is found that while the choice of the exchange-correlation functional can strongly influence the quantitative results, our qualitative conclusions hold irrespective of the functional employed.

  3. Identification and characterization of an iron ABC transporter operon in Gluconacetobacter diazotrophicus Pal 5.

    PubMed

    Urzúa, Lucia Soto; Vázquez-Candanedo, Ada P; Sánchez-Espíndola, Adriana; Ramírez, Carlos Ávila; Baca, Beatriz E

    2013-06-01

    Gluconacetobacter diazotrophicus is a nitrogen-fixing bacterium and endophyte of sugarcane. We have cloned and sequenced the genes coding for the components of the iron ABC-type acquisition system of G. diazotrophicus. Sequence analysis revealed three ORFs, (feuA, feuB, and feuC) organized as an operon and encoding polypeptides of 346 (38 kDa), 342 (34.2 kDa), and 240 (26 kDa) amino acids, respectively. The deduced translation products of the feu operon showed similarity with a periplasmic solute-binding protein (FeuA), permease (FeuB), and ATPase (FeuC) involved in Fe transport. The role of FeuB in the survival of G. diazotrophicus under iron depletion was evaluated by comparing the ability of wild-type and FeuB-Km(R) -mutant strains in a medium without iron supplementation and in a medium containing 2, 2'-dipyridyl (DP). Growth of the mutant was affected in the medium containing DP. The operon was expressed at higher levels in cells depleted for iron than in those that contained the metal. A decrease in nitrogenase activity was observed with the FeuB-Km(R) -mutant strain that with the wild-type under iron deficiency conditions, suggesting that the Feu operon play role in Fe nutrition of G. diazotrophicus. PMID:23624722

  4. Transportation Anslysis Simulation System

    SciTech Connect

    2004-08-23

    TRANSIMS version 3.1 is an integrated set of analytical and simulation models and supporting databases. The system is designed to create a virtual metropolitan region with representation of each of the region’s individuals, their activities and the transportation infrastructure they use. TRANSIMS puts into practice a new, disaggregate approach to travel demand modeling using agent-based micro-simulation technology. TRANSIMS methodology creates a virtual metropolitan region with representation of the transportation infrastructure and the population, at the level of households and individual travelers. Trips a planned to satisfy the population’s activity pattems at the individual traveler level. TRANSIMS then simulates the movement of travelers and vehicles across the transportation network using multiple modes, including car, transit, bike and walk, on a second-by-second basis. Metropolitan planners must plan growth of their cities according to the stringent transportation system planning requirements of the Interniodal Surface Transportation Efficiency Act of 1991, the Clean Air Act Amendments of 1990 and other similar laws and regulations. These require each state and its metropotitan regions to work together to develop short and long term transportation improvement plans. The plans must (1) estimate the future transportation needs for travelers and goods movements, (2) evaluate ways to manage and reduce congestion, (3) examine the effectiveness of building new roads and transit systems, and (4) limit the environmental impact of the various strategies. The needed consistent and accurate transportation improvement plans require an analytical capability that properly accounts for travel demand, human behavior, traffic and transit operations, major investments, and environmental effects. Other existing planning tools use aggregated information and representative behavior to predict average response and average use of transportation facilities. They do not account

  5. Transportation Anslysis Simulation System

    Energy Science and Technology Software Center (ESTSC)

    2004-08-23

    TRANSIMS version 3.1 is an integrated set of analytical and simulation models and supporting databases. The system is designed to create a virtual metropolitan region with representation of each of the region’s individuals, their activities and the transportation infrastructure they use. TRANSIMS puts into practice a new, disaggregate approach to travel demand modeling using agent-based micro-simulation technology. TRANSIMS methodology creates a virtual metropolitan region with representation of the transportation infrastructure and the population, at themore » level of households and individual travelers. Trips a planned to satisfy the population’s activity pattems at the individual traveler level. TRANSIMS then simulates the movement of travelers and vehicles across the transportation network using multiple modes, including car, transit, bike and walk, on a second-by-second basis. Metropolitan planners must plan growth of their cities according to the stringent transportation system planning requirements of the Interniodal Surface Transportation Efficiency Act of 1991, the Clean Air Act Amendments of 1990 and other similar laws and regulations. These require each state and its metropotitan regions to work together to develop short and long term transportation improvement plans. The plans must (1) estimate the future transportation needs for travelers and goods movements, (2) evaluate ways to manage and reduce congestion, (3) examine the effectiveness of building new roads and transit systems, and (4) limit the environmental impact of the various strategies. The needed consistent and accurate transportation improvement plans require an analytical capability that properly accounts for travel demand, human behavior, traffic and transit operations, major investments, and environmental effects. Other existing planning tools use aggregated information and representative behavior to predict average response and average use of transportation facilities. They do not

  6. A lunar transportation system

    NASA Technical Reports Server (NTRS)

    1986-01-01

    Due to large amounts of oxygen required for space travel, a method of mining, transporting, and storing this oxygen in space would facilitate further space exploration. The following project deals specifically with the methods for transporting liquid oxygen from the lunar surface to the Lunar Orbit (LO) space station, and then to the Lower Earth Orbit (LEO) space station. Two vehicles were designed for operation between the LEO and LO space stations. The first of these vehicles is an aerobraked design vehicle. The Aerobrake Orbital Transfer Vehicle (OTV) is capable of transporting 5000 lbm of payload to LO while returning to LEO with 60,000 lbm of liquid oxygen, and thus meet mission requirements. The second vehicle can deliver 18,000 lbm of payload to LO and is capable of bringing 60,000 lbm of liquid oxygen back to LEO. A lunar landing vehicle was also designed for operation between LO and the established moon base. The use of an electromagnetic railgun as a method for launching the lunar lander was also investigated. The feasibility of the railgun is doubtful at this time. A system of spheres was also designed for proper storing and transporting of the liquid oxygen. The system assumes a safe means for transferring the liquid oxygen from tank to tank is operational. A sophisticated life support system was developed for both the OTV and the lunar lander. This system focuses on such factors as the vehicle environment, waste management, water requirements, food requirements, and oxygen requirements.

  7. Lunar transportation system

    NASA Technical Reports Server (NTRS)

    1993-01-01

    The University Space Research Association (USRA) requested the University of Minnesota Spacecraft Design Team to design a lunar transportation infrastructure. This task was a year long design effort culminating in a complete conceptual design and presentation at Johnson Space Center. The mission objective of the design group was to design a system of vehicles to bring a habitation module, cargo, and crew to the lunar surface from LEO and return either or both crew and cargo safely to LEO while emphasizing component commonality, reusability, and cost effectiveness. During the course of the design, the lunar transportation system (LTS) has taken on many forms. The final design of the system is composed of two vehicles, a lunar transfer vehicle (LTV) and a lunar excursion vehicle (LEV). The LTV serves as an efficient orbital transfer vehicle between the earth and the moon while the LEV carries crew and cargo to the lunar surface. Presented in the report are the mission analysis, systems layout, orbital mechanics, propulsion systems, structural and thermal analysis, and crew systems, avionics, and power systems for this lunar transportation concept.

  8. The Bacillus subtilis EfeUOB transporter is essential for high-affinity acquisition of ferrous and ferric iron.

    PubMed

    Miethke, Marcus; Monteferrante, Carmine G; Marahiel, Mohamed A; van Dijl, Jan Maarten

    2013-10-01

    Efficient uptake of iron is of critical importance for growth and viability of microbial cells. Nevertheless, several mechanisms for iron uptake are not yet clearly defined. Here we report that the widely conserved transporter EfeUOB employs an unprecedented dual-mode mechanism for acquisition of ferrous (Fe[II]) and ferric (Fe[III]) iron in the bacterium Bacillus subtilis. We show that the binding protein EfeO and the permease EfeU form a minimal complex for ferric iron uptake. The third component EfeB is a hemoprotein that oxidizes ferrous iron to ferric iron for uptake by EfeUO. Accordingly, EfeB promotes growth under microaerobic conditions where ferrous iron is more abundant. Notably, EfeB also fulfills a vital role in cell envelope stress protection by eliminating reactive oxygen species that accumulate in the presence of ferrous iron. In conclusion, the EfeUOB system contributes to the high-affinity uptake of iron that is available in two different oxidation states. PMID:23764491

  9. Transportation Systems Center

    SciTech Connect

    Greer, G.S.

    1992-07-01

    The Transportation Systems Center at Sandia Laboratory performs research, development, and implementation of technologies that enhance the safe movement of people, goods, and information. Our focus is on systems engineering. However, we realize that to understand the puzzle, you must also understand the pieces. This brochure describes some of the activities currently underway at the Center and presents the breadth and depth of our capabilities. Please contact the noted, individuals for more, information.

  10. Heat transport system

    DOEpatents

    Pierce, Bill L.

    1978-01-01

    A heat transport system of small size which can be operated in any orientation consists of a coolant loop containing a vaporizable liquid as working fluid and includes in series a vaporizer, a condenser and two one-way valves and a pressurizer connected to the loop between the two valves. The pressurizer may be divided into two chambers by a flexible diaphragm, an inert gas in one chamber acting as a pneumatic spring for the system.

  11. IRON REMOVAL PROCESSES: DESIGN OF NEW SYSTEMS

    EPA Science Inventory

    The recently promulgated Arsenic Rule will require that many new drinking water systems treat their water to remove arsenic. Many groundwaters that have arsenic in their source water also have iron in their water. As a result, arsenic treatment at these sites will most likely b...

  12. Competitive adsorption, displacement, and transport of organic matter on iron oxide: II. Displacement and transport

    SciTech Connect

    Gu, B; Mehlhorn, T.L.; Liang, Liyuan

    1996-08-01

    The competitive interactions between organic matter compounds and mineral surfaces are poorly understood, yet these interactions may play a significant role in the stability and co-transport of mineral colloids and/or environmental contaminants. In this study, the processes of competitive adsorption, displacement, and transport of Suwannee River natural organic matter (SR-NOM) are investigated with several model organic compounds in packed beds of iron oxide-coated quartz columns. Results demonstrated that strongly-binding organic compounds are competitively adsorbed and displace those weakly-bound organic compounds along the flow path. Among the four organic compounds studied, polyacrylic acid (PAA) appeared to be the most competitive, whereas SR-NOM was more competitive than phthalic and salicylic acids. A diffuse adsorption and sharp desorption front (giving an appearance of irreversible adsorption) of the SR-NOM breakthrough curves are explained as being a result of the competitive time-dependent adsorption and displacement processes between different organic components within the SR-NOM. The stability and transport of iron oxide colloids varied as one organic component competitively displaces another. Relatively large quantities of iron oxide colloids are transported when the more strongly-binding PAA competitively displaces the weakly-binding SR-NOM or when SR-NOM competitively displaces phthalic and salicylic acids. Results of this study suggest that the chemical composition and hence the functional behavior of NOM (e.g., in stabilizing mineral colloids and in complexing contaminants) can change along its flow path as a result of the dynamic competitive interactions between heterogeneous NOM subcomponents. Further studies are needed to better define and quantify these NOM components as well as their roles in contaminant partitioning and transport. 37 refs., 10 figs.

  13. Identification and Characterization of Cronobacter Iron Acquisition Systems

    PubMed Central

    Grim, C. J.; Kothary, M. H.; Gopinath, G.; Jarvis, K. G.; Beaubrun, J. Jean-Gilles; McClelland, M.; Tall, B. D.

    2012-01-01

    Cronobacter spp. are emerging pathogens that cause severe infantile meningitis, septicemia, or necrotizing enterocolitis. Contaminated powdered infant formula has been implicated as the source of Cronobacter spp. in most cases, but questions still remain regarding the natural habitat and virulence potential for each strain. The iron acquisition systems in 231 Cronobacter strains isolated from different sources were identified and characterized. All Cronobacter spp. have both the Feo and Efe systems for acquisition of ferrous iron, and all plasmid-harboring strains (98%) have the aerobactin-like siderophore, cronobactin, for transport of ferric iron. All Cronobacter spp. have the genes encoding an enterobactin-like siderophore, although it was not functional under the conditions tested. Furthermore, all Cronobacter spp. have genes encoding five receptors for heterologous siderophores. A ferric dicitrate transport system (fec system) is encoded specifically by a subset of Cronobacter sakazakii and C. malonaticus strains, of which a high percentage were isolated from clinical samples. Phylogenetic analysis confirmed that the fec system is most closely related to orthologous genes present in human-pathogenic bacterial strains. Moreover, all strains of C. dublinensis and C. muytjensii encode two receptors, FcuA and Fct, for heterologous siderophores produced by plant pathogens. Identification of putative Fur boxes and expression of the genes under iron-depleted conditions revealed which genes and operons are components of the Fur regulon. Taken together, these results support the proposition that C. sakazakii and C. malonaticus may be more associated with the human host and C. dublinensis and C. muytjensii with plants. PMID:22706064

  14. Identification and characterization of Cronobacter iron acquisition systems.

    PubMed

    Grim, C J; Kothary, M H; Gopinath, G; Jarvis, K G; Beaubrun, J Jean-Gilles; McClelland, M; Tall, B D; Franco, A A

    2012-09-01

    Cronobacter spp. are emerging pathogens that cause severe infantile meningitis, septicemia, or necrotizing enterocolitis. Contaminated powdered infant formula has been implicated as the source of Cronobacter spp. in most cases, but questions still remain regarding the natural habitat and virulence potential for each strain. The iron acquisition systems in 231 Cronobacter strains isolated from different sources were identified and characterized. All Cronobacter spp. have both the Feo and Efe systems for acquisition of ferrous iron, and all plasmid-harboring strains (98%) have the aerobactin-like siderophore, cronobactin, for transport of ferric iron. All Cronobacter spp. have the genes encoding an enterobactin-like siderophore, although it was not functional under the conditions tested. Furthermore, all Cronobacter spp. have genes encoding five receptors for heterologous siderophores. A ferric dicitrate transport system (fec system) is encoded specifically by a subset of Cronobacter sakazakii and C. malonaticus strains, of which a high percentage were isolated from clinical samples. Phylogenetic analysis confirmed that the fec system is most closely related to orthologous genes present in human-pathogenic bacterial strains. Moreover, all strains of C. dublinensis and C. muytjensii encode two receptors, FcuA and Fct, for heterologous siderophores produced by plant pathogens. Identification of putative Fur boxes and expression of the genes under iron-depleted conditions revealed which genes and operons are components of the Fur regulon. Taken together, these results support the proposition that C. sakazakii and C. malonaticus may be more associated with the human host and C. dublinensis and C. muytjensii with plants. PMID:22706064

  15. Expression of peanut Iron Regulated Transporter 1 in tobacco and rice plants confers improved iron nutrition.

    PubMed

    Xiong, Hongchun; Guo, Xiaotong; Kobayashi, Takanori; Kakei, Yusuke; Nakanishi, Hiromi; Nozoye, Tomoko; Zhang, Lixia; Shen, Hongyun; Qiu, Wei; Nishizawa, Naoko K; Zuo, Yuanmei

    2014-07-01

    Iron (Fe) limitation is a widespread agricultural problem in calcareous soils and severely limits crop production. Iron Regulated Transporter 1 (IRT1) is a key component for Fe uptake from the soil in dicot plants. In this study, the peanut (Arachis hypogaea L.) AhIRT1 was introduced into tobacco and rice plants using an Fe-deficiency-inducible artificial promoter. Induced expression of AhIRT1 in tobacco plants resulted in accumulation of Fe in young leaves under Fe deficient conditions. Even under Fe-excess conditions, the Fe concentration was also markedly enhanced, suggesting that the Fe status did not affect the uptake and translocation of Fe by AhIRT1 in the transgenic plants. Most importantly, the transgenic tobacco plants showed improved tolerance to Fe limitation in culture in two types of calcareous soils. Additionally, the induced expression of AhIRT1 in rice plants also resulted in high tolerance to low Fe availability in calcareous soils. PMID:24727792

  16. Characterization of a Dipartite Iron Uptake System from Uropathogenic Escherichia coli Strain F11*

    PubMed Central

    Koch, Doreen; Chan, Anson C. K.; Murphy, Michael E. P.; Lilie, Hauke; Grass, Gregor; Nies, Dietrich H.

    2011-01-01

    In the uropathogenic Escherichia coli strain F11, in silico genome analysis revealed the dicistronic iron uptake operon fetMP, which is under iron-regulated control mediated by the Fur regulator. The expression of fetMP in a mutant strain lacking known iron uptake systems improved growth under iron depletion and increased cellular iron accumulation. FetM is a member of the iron/lead transporter superfamily and is essential for iron uptake by the Fet system. FetP is a periplasmic protein that enhanced iron uptake by FetM. Recombinant FetP bound Cu(II) and the iron analog Mn(II) at distinct sites. The crystal structure of the FetP dimer reveals a copper site in each FetP subunit that adopts two conformations: CuA with a tetrahedral geometry composed of His44, Met90, His97, and His127, and CuB, a second degenerate octahedral geometry with the addition of Glu46. The copper ions of each site occupy distinct positions and are separated by ∼1.3 Å. Nearby, a putative additional Cu(I) binding site is proposed as an electron source that may function with CuA/CuB displacement to reduce Fe(III) for transport by FetM. Together, these data indicate that FetMP is an additional iron uptake system composed of a putative iron permease and an iron-scavenging and potentially iron-reducing periplasmic protein. PMID:21596746

  17. The Arabidopsis YELLOW STRIPE LIKE4 and 6 transporters control iron release from the chloroplast.

    PubMed

    Divol, Fanchon; Couch, Daniel; Conéjéro, Geneviève; Roschzttardtz, Hannetz; Mari, Stéphane; Curie, Catherine

    2013-03-01

    In most plant cell types, the chloroplast represents the largest sink for iron, which is both essential for chloroplast metabolism and prone to cause oxidative damage. Here, we show that to buffer the potentially harmful effects of iron, besides ferritins for storage, the chloroplast is equipped with specific iron transporters that respond to iron toxicity by removing iron from the chloroplast. We describe two transporters of the YELLOW STRIPE1-LIKE family from Arabidopsis thaliana, YSL4 and YSL6, which are likely to fulfill this function. Knocking out both YSL4 and YSL6 greatly reduces the plant's ability to cope with excess iron. Biochemical and immunolocalization analyses showed that YSL6 resides in the chloroplast envelope. Elemental analysis and histochemical staining indicate that iron is trapped in the chloroplasts of the ysl4 ysl6 double mutants, which also accumulate ferritins. Also, vacuolar iron remobilization and NRAMP3/4 expression are inhibited. Furthermore, ubiquitous expression of YSL4 or YSL6 dramatically reduces plant tolerance to iron deficiency and decreases chloroplastic iron content. These data demonstrate a fundamental role for YSL4 and YSL6 in managing chloroplastic iron. YSL4 and YSL6 expression patterns support their physiological role in detoxifying iron during plastid dedifferentiation occurring in embryogenesis and senescence. PMID:23512854

  18. Chloroplast Iron Transport Proteins – Function and Impact on Plant Physiology

    PubMed Central

    López-Millán, Ana F.; Duy, Daniela; Philippar, Katrin

    2016-01-01

    Chloroplasts originated about three billion years ago by endosymbiosis of an ancestor of today’s cyanobacteria with a mitochondria-containing host cell. During evolution chloroplasts of higher plants established as the site for photosynthesis and thus became the basis for all life dependent on oxygen and carbohydrate supply. To fulfill this task, plastid organelles are loaded with the transition metals iron, copper, and manganese, which due to their redox properties are essential for photosynthetic electron transport. In consequence, chloroplasts for example represent the iron-richest system in plant cells. However, improvement of oxygenic photosynthesis in turn required adaptation of metal transport and homeostasis since metal-catalyzed generation of reactive oxygen species (ROS) causes oxidative damage. This is most acute in chloroplasts, where radicals and transition metals are side by side and ROS-production is a usual feature of photosynthetic electron transport. Thus, on the one hand when bound by proteins, chloroplast-intrinsic metals are a prerequisite for photoautotrophic life, but on the other hand become toxic when present in their highly reactive, radical generating, free ionic forms. In consequence, transport, storage and cofactor-assembly of metal ions in plastids have to be tightly controlled and are crucial throughout plant growth and development. In the recent years, proteins for iron transport have been isolated from chloroplast envelope membranes. Here, we discuss their putative functions and impact on cellular metal homeostasis as well as photosynthetic performance and plant metabolism. We further consider the potential of proteomic analyses to identify new players in the field. PMID:27014281

  19. Mars Equipment Transport System

    NASA Astrophysics Data System (ADS)

    Sorrells, Cindy; Geiger, Michelle; Ohanlon, Sean; Pieloch, Stuart; Brogan, Nick

    1993-12-01

    Mechanical Engineering Senior Design Project 1 (ME4182) is a part of the NASA/University Advanced Design Program. Under this program, NASA allocates money and resources to students to be used in design work for a specified topic. The current topic is the exploration and colonization of Mars. The specific area in which we are to work is the transportation of the modules in which astronauts will live while on Mars. NASA is concerned about the weight of the module transferring system, as the shipping cost to Mars is quite expensive. NASA has specified that the weight of the system is to be minimized in order to reduce the shipping costs.

  20. Mars Equipment Transport System

    NASA Technical Reports Server (NTRS)

    Sorrells, Cindy; Geiger, Michelle; Ohanlon, Sean; Pieloch, Stuart; Brogan, Nick

    1993-01-01

    Mechanical Engineering Senior Design Project 1 (ME4182) is a part of the NASA/University Advanced Design Program. Under this program, NASA allocates money and resources to students to be used in design work for a specified topic. The current topic is the exploration and colonization of Mars. The specific area in which we are to work is the transportation of the modules in which astronauts will live while on Mars. NASA is concerned about the weight of the module transferring system, as the shipping cost to Mars is quite expensive. NASA has specified that the weight of the system is to be minimized in order to reduce the shipping costs.

  1. Physiology of iron transport and the hemochromatosis gene.

    PubMed

    Pietrangelo, Antonello

    2002-03-01

    Iron is essential for fundamental cell functions but is also a catalyst for chemical reactions involving free radical formation, potentially leading to oxidative stress and cell damage. Cellular iron levels are therefore carefully regulated to maintain an adequate substrate while also minimizing the pool of potentially toxic "free iron." The main control of body iron homeostasis in higher organisms is placed in the duodenum, where dietary iron is absorbed, whereas no controlled means of eliminating unwanted iron have evolved in mammals. Hereditary hemochromatosis, the prototype of deregulated iron homeostasis in humans, is due to inappropriately increased iron absorption and is commonly associated to a mutated HFE gene. The HFE protein is homologous to major histocompatibility complex class I proteins but is not an iron carrier, whereas biochemical and cell biological studies have shown that the transferrin receptor, the main protein devoted to cellular uptake of transferrin iron, interacts with HFE. This review focuses on recent advances in iron research and presents a model of HFE function in iron metabolism. PMID:11841990

  2. Magnetically Coupled Transport System

    SciTech Connect

    Breshears, S.A.

    1999-01-26

    Throughout the DOE complex, materials are routinely transported within glovebox processing lines. Cylindrical product cans, crucibles, sample containers, tools, and waste products are all examples of items that are moved between equipment stations during glovebox operations. Traditional transport methods have included manual handling using tongs, chain and belt conveyors, carts with pull wires, and overhead hoists on monorails. These methods rely on hands-on operations and/or utilize high maintenance equipment located inside the gloveboxes, which can lead to high radiation exposure to personnel and can generate large amounts of radioactive waste. One innovative approach incorporates linear induction motors (LIMs) so that high maintenance items are located outside the gloveboxes, but LIMs produce heat, do not move smoothly over a wide range of velocities, and are not locked in position at zero velocity. Savannah River Technology Center (SRTC) engineers have developed and demonstrated a concept for a magnetically coupled transport system to transfer material within process lines and from line to line. This automated system significantly reduces hands-on operations. Linear actuators and lead screws provide smooth horizontal and vertical movement. Rare earth magnetic coupling technology allows the majority of the equipment to be located outside the glovebox, simplifying maintenance and minimizing radioactive waste.

  3. Space Transportation Systems Technologies

    NASA Technical Reports Server (NTRS)

    Laue, Jay H.

    2001-01-01

    This document is the final report by the Science Applications International Corporation (SAIC) on contracted support provided to the National Aeronautics and Space Administration (NASA) under Contract NAS8-99060, 'Space Transportation Systems Technologies'. This contract, initiated by NASA's Marshall Space Flight Center (MSFC) on February 8, 1999, was focused on space systems technologies that directly support NASA's space flight goals. It was awarded as a Cost-Plus-Incentive-Fee (CPIF) contract to SAIC, following a competitive procurement via NASA Research Announcement, NRA 8-21. This NRA was specifically focused on tasks related to Reusable Launch Vehicles (RLVs). Through Task Area 3 (TA-3), "Other Related Technology" of this NRA contract, SAIC extensively supported the Space Transportation Directorate of MSFC in effectively directing, integrating, and setting its mission, operations, and safety priorities for future RLV-focused space flight. Following an initially contracted Base Year (February 8, 1999 through September 30, 1999), two option years were added to the contract. These were Option Year 1 (October 1, 1999 through September 30, 2000) and Option Year 2 (October 1, 2000 through September 30, 2001). This report overviews SAIC's accomplishments for the Base Year, Option Year 1, and Option Year 2, and summarizes the support provided by SAIC to the Space Transportation Directorate, NASA/MSFC.

  4. Mars transportation system

    NASA Technical Reports Server (NTRS)

    Garrard, William; Vano, Andrew; Rutherford, Dave

    1992-01-01

    The University of Minnesota Advanced Space Design Program has developed a sample Mars exploration scenario. The purpose of the design project is to enhance NASA and university interaction, to provide fresh ideas to NASA, and to provide real world design problems to engineering students. The Mars Transportation System in this paper is designed to transport a crew of six astronauts to the Martian surface and return them to Low Earth Orbit (LEO) starting in the year 2016. The proposed vehicle features such advanced technologies as nuclear propulsion, nuclear power generation, and aerobraking. Three missions are planned. Orbital trajectories are of the conjunction class with an inbound Venus swingby providing a 60-day surface stay at Mars and an average total trip time of 520 days.

  5. SURFACE COMPLEXATION OF ACTINIDES WITH IRON OXIDES: IMPLICATIONS FOR RADIONUCLIDE TRANSPORT IN NEAR-SURFACE AQUIFERS

    SciTech Connect

    J.L. Jerden Jr.; A.J. Kropf; Y. Tsai

    2005-08-25

    The surface complexation of actinides with iron oxides plays a key role in actinide transport and retardation in geosphere-biosphere systems. The development of accurate actinide transport models therefore requires a mechanistic understanding of surface complexation reactions (i.e. knowledge of chemical speciation at mineral/fluid interfaces). Iron oxides are particularly important actinide sorbents due to their pH dependent surface charges, relatively high surface areas and ubiquity in oxic and suboxic near-surface systems. In this paper we present results from field and laboratory investigations that elucidate the mechanisms involved in binding uranium and neptunium to iron oxide mineral substrates in near neutral groundwaters. The field study involved sampling and characterizing uranium-bearing groundwaters and solids from a saprolite aquifer overlying an unmined uranium deposit in the Virginia Piedmont. The groundwaters were analyzed by inductively coupled mass spectrometry and ion chromatography and the aquifer solids were analyzed by electron microprobe. The laboratory study involved a series of batch sorption tests in which U(VI) and Np(V) were reacted with goethite, hematite and magnetite in simulated groundwaters. The pH, ionic strength, aging time, and sorbent/sorbate ratios were varied in these experiments. The oxidation state and coordination environment of neptunium in solutions and sorbents from the batch tests were characterized by X-ray absorption spectroscopy (XAS) at the Advanced Photon Source, Argonne National Laboratory. Results from this work indicate that, in oxidizing near-surface aquifers, the dissolved concentration of uranium may be limited to less than 30 parts per billion due to uptake by iron oxide mineral coatings and the precipitation of sparingly soluble U(VI) phosphate minerals. Results from the batch adsorption tests showed that, in near neutral groundwaters, a significant fraction of the uranium and neptunium adsorbed as strongly

  6. New Iron Acquisition System in Bacteroidetes

    PubMed Central

    Manfredi, Pablo; Lauber, Frédéric; Renzi, Francesco; Hack, Katrin; Hess, Estelle

    2014-01-01

    Capnocytophaga canimorsus, a dog mouth commensal and a member of the Bacteroidetes phylum, causes rare but often fatal septicemia in humans that have been in contact with a dog. Here, we show that C. canimorsus strains isolated from human infections grow readily in heat-inactivated human serum and that this property depends on a typical polysaccharide utilization locus (PUL), namely, PUL3 in strain Cc5. PUL are a hallmark of Bacteroidetes, and they encode various products, including surface protein complexes that capture and process polysaccharides or glycoproteins. The archetype system is the Bacteroides thetaiotaomicron Sus system, devoted to starch utilization. Unexpectedly, PUL3 conferred the capacity to acquire iron from serotransferrin (STF), and this capacity required each of the seven encoded proteins, indicating that a whole Sus-like machinery is acting as an iron capture system (ICS), a new and unexpected function for Sus-like machinery. No siderophore could be detected in the culture supernatant of C. canimorsus, suggesting that the Sus-like machinery captures iron directly from transferrin, but this could not be formally demonstrated. The seven genes of the ICS were found in the genomes of several opportunistic pathogens from the Capnocytophaga and Prevotella genera, in different isolates of the severe poultry pathogen Riemerella anatipestifer, and in strains of Bacteroides fragilis and Odoribacter splanchnicus isolated from human infections. Thus, this study describes a new type of ICS that evolved in Bacteroidetes from a polysaccharide utilization system and most likely represents an important virulence factor in this group. PMID:25368114

  7. New iron acquisition system in Bacteroidetes.

    PubMed

    Manfredi, Pablo; Lauber, Frédéric; Renzi, Francesco; Hack, Katrin; Hess, Estelle; Cornelis, Guy R

    2015-01-01

    Capnocytophaga canimorsus, a dog mouth commensal and a member of the Bacteroidetes phylum, causes rare but often fatal septicemia in humans that have been in contact with a dog. Here, we show that C. canimorsus strains isolated from human infections grow readily in heat-inactivated human serum and that this property depends on a typical polysaccharide utilization locus (PUL), namely, PUL3 in strain Cc5. PUL are a hallmark of Bacteroidetes, and they encode various products, including surface protein complexes that capture and process polysaccharides or glycoproteins. The archetype system is the Bacteroides thetaiotaomicron Sus system, devoted to starch utilization. Unexpectedly, PUL3 conferred the capacity to acquire iron from serotransferrin (STF), and this capacity required each of the seven encoded proteins, indicating that a whole Sus-like machinery is acting as an iron capture system (ICS), a new and unexpected function for Sus-like machinery. No siderophore could be detected in the culture supernatant of C. canimorsus, suggesting that the Sus-like machinery captures iron directly from transferrin, but this could not be formally demonstrated. The seven genes of the ICS were found in the genomes of several opportunistic pathogens from the Capnocytophaga and Prevotella genera, in different isolates of the severe poultry pathogen Riemerella anatipestifer, and in strains of Bacteroides fragilis and Odoribacter splanchnicus isolated from human infections. Thus, this study describes a new type of ICS that evolved in Bacteroidetes from a polysaccharide utilization system and most likely represents an important virulence factor in this group. PMID:25368114

  8. Effects of electron correlations on transport properties of iron at Earth's core conditions.

    PubMed

    Zhang, Peng; Cohen, R E; Haule, K

    2015-01-29

    Earth's magnetic field has been thought to arise from thermal convection of molten iron alloy in the outer core, but recent density functional theory calculations have suggested that the conductivity of iron is too high to support thermal convection, resulting in the investigation of chemically driven convection. These calculations for resistivity were based on electron-phonon scattering. Here we apply self-consistent density functional theory plus dynamical mean-field theory (DFT + DMFT) to iron and find that at high temperatures electron-electron scattering is comparable to the electron-phonon scattering, bringing theory into agreement with experiments and solving the transport problem in Earth's core. The conventional thermal dynamo picture is safe. We find that electron-electron scattering of d electrons is important at high temperatures in transition metals, in contrast to textbook analyses since Mott, and that 4s electron contributions to transport are negligible, in contrast to numerous models used for over fifty years. The DFT+DMFT method should be applicable to other high-temperature systems where electron correlations are important. PMID:25631449

  9. Ferric Uptake Regulator Fur Control of Putative Iron Acquisition Systems in Clostridium difficile

    PubMed Central

    Ellermeier, Craig D.

    2015-01-01

    ABSTRACT Clostridium difficile is an anaerobic, Gram-positive, spore-forming opportunistic pathogen and is the most common cause of hospital-acquired infectious diarrhea. Although iron acquisition in the host is a key to survival of bacterial pathogens, high levels of intracellular iron can increase oxidative damage. Therefore, expression of iron acquisition mechanisms is tightly controlled by transcriptional regulators. We identified a C. difficile homologue of the master bacterial iron regulator Fur. Using targetron mutagenesis, we generated a fur insertion mutant of C. difficile. To identify the genes regulated by Fur in C. difficile, we used microarray analysis to compare transcriptional differences between the fur mutant and the wild type when grown in high-iron medium. The fur mutant had increased expression of greater than 70 transcriptional units. Using quantitative reverse transcriptase PCR (qRT-PCR), we analyzed several of the Fur-regulated genes identified by the microarray and verified that they are both iron and Fur regulated in C. difficile. Among those Fur- and iron-repressed genes were C. difficile genes encoding 7 putative cation transport systems of different classes. We found that Fur was able to bind the DNA upstream of three Fur-repressed genes in electrophoretic mobility shift assays. We also demonstrate that expression of Fur-regulated putative iron acquisition systems was increased during C. difficile infection using the hamster model. Our data suggest that C. difficile expresses multiple iron transport mechanisms in response iron depletion in vitro and in vivo. IMPORTANCE Clostridium difficile is the most common cause of hospital-acquired infectious diarrhea and has been recently classified as an “urgent” antibiotic resistance threat by the CDC. To survive and cause disease, most bacterial pathogens must acquire the essential enzymatic cofactor iron. While import of adequate iron is essential for most bacterial growth, excess

  10. Ferroportin-mediated iron transport: expression and regulation

    PubMed Central

    Ward, Diane; Kaplan, Jerry

    2013-01-01

    The distinguishing feature between iron homeostasis in single versus multicellular organisms is the need for multicellular organisms to transfer iron from sites of absorption to sites of utilization and storage. Ferroportin is the only known iron exporter and ferroportin plays an essential role in the export of iron from cells to blood. Ferroportin can be regulated at many different levels including transcriptionally, post-transcriptionally, through mRNA stability and post-translationally, through protein turnover. Additionally, ferroportin may be regulated in both cell-dependent and cell-autonomous fashions. Regulation of ferroportin is critical for iron homeostasis as alterations in ferroportin may result in either iron deficiency or iron overload. PMID:22440327

  11. Systemic and tumor level iron regulation in men with colorectal cancer: a case control study

    PubMed Central

    2014-01-01

    Background Increased cellular iron exposure is associated with colorectal cancer (CRC) risk. Hepcidin, a liver peptide hormone, acts as the primary regulator of systemic iron status by blocking iron release from enterocytes into plasma. Concentrations are decreased during low iron status and increased during inflammation. The role of hepcidin and the factors influencing its regulation in CRC remains largely unknown. This study explored systemic and tumor level iron regulation in men with CRC. Methods The participants were 20 CRC cases and 20 healthy control subjects. Colonic tissue (adenocarcinoma [cases] healthy mucosa [controls]) was subjected to quantitative PCR (hepcidin, iron transporters and IL-6) and Perls’ iron staining. Serum was analyzed using ELISA for hepcidin, iron status (sTfR) and inflammatory markers (CRP, IL-6, TNF-α). Anthropometrics, dietary iron intake and medical history were obtained. Results Cases and controls were similar in demographics, medication use and dietary iron intake. Systemically, cases compared to controls had lower iron status (sTfR: 21.6 vs 11.8 nmol/L, p < 0.05) and higher marker of inflammation (CRP: 8.3 vs 3.4 μg/mL, p < 0.05). Serum hepcidin was mildly decreased in cases compared to controls; however, it was within the normal range for both groups. Within colonic tissue, 30% of cases (6/20) presented iron accumulation compared to 5% of controls (1/20) (χ2 = 5.0; p < 0.05) and higher marker of inflammation (IL-6: 9.4-fold higher compared to controls, p < 0.05). Presence of adenocarcinoma iron accumulation was associated with higher serum hepcidin (iron accumulation group 80.8 vs iron absence group 22.0 ng/mL, p < 0.05). Conclusions While CRC subjects had serum hepcidin concentrations in the normal range, it was higher given their degree of iron restriction. Inappropriately elevated serum hepcidin may reduce duodenal iron absorption and further increase colonic adenocarcinoma iron exposure

  12. Mars transportation system synthesis

    NASA Astrophysics Data System (ADS)

    Young, Archie C.; Mulqueen, John A.; Emrich, William J.

    Performance and requirements synthesized to support the manned Mars mission of the Space Exploration Initiative (SEI) are presented. Emphasis is placed on the Mars transportation system (MTS), which uses nuclear thermal rocket (NTR) propulsion technology associated with accomplishing the manned Mars mission. Data are also presented for a propulsion system options comparison of chemical/aerobrake and nuclear electric propulsion systems. Vehicle- and weight-scaling are used to determine the MTS mass, size, and performance range required for different Mars mission durations. The split sprint, opposition, and conjunction class mission modes are employed to determine the MTS requirements envelope. MTS sensitivity to Mars surface payload, crew size, Mars orbit payload, NTR engine thrust level, engine specific impulse, and NTR engine thrust-to-weight ratio are synthesized. A suggested NTR technology level to accomplish both cargo and piloted Mars missions is discussed.

  13. Ceruloplasmin ferroxidase activity stimulates cellular iron uptake by a trivalent cation-specific transport mechanism

    NASA Technical Reports Server (NTRS)

    Attieh, Z. K.; Mukhopadhyay, C. K.; Seshadri, V.; Tripoulas, N. A.; Fox, P. L.

    1999-01-01

    The balance required to maintain appropriate cellular and tissue iron levels has led to the evolution of multiple mechanisms to precisely regulate iron uptake from transferrin and low molecular weight iron chelates. A role for ceruloplasmin (Cp) in vertebrate iron metabolism is suggested by its potent ferroxidase activity catalyzing conversion of Fe2+ to Fe3+, by identification of yeast copper oxidases homologous to Cp that facilitate high affinity iron uptake, and by studies of "aceruloplasminemic" patients who have extensive iron deposits in multiple tissues. We have recently shown that Cp increases iron uptake by cultured HepG2 cells. In this report, we investigated the mechanism by which Cp stimulates cellular iron uptake. Cp stimulated the rate of non-transferrin 55Fe uptake by iron-deficient K562 cells by 2-3-fold, using a transferrin receptor-independent pathway. Induction of Cp-stimulated iron uptake by iron deficiency was blocked by actinomycin D and cycloheximide, consistent with a transcriptionally induced or regulated transporter. Cp-stimulated iron uptake was completely blocked by unlabeled Fe3+ and by other trivalent cations including Al3+, Ga3+, and Cr3+, but not by divalent cations. These results indicate that Cp utilizes a trivalent cation-specific transporter. Cp ferroxidase activity was required for iron uptake as shown by the ineffectiveness of two ferroxidase-deficient Cp preparations, copper-deficient Cp and thiomolybdate-treated Cp. We propose a model in which iron reduction and subsequent re-oxidation by Cp are essential for an iron uptake pathway with high ion specificity.

  14. Alternate transportation system

    NASA Technical Reports Server (NTRS)

    Zertuche, Tony; Mckinnie, James

    1988-01-01

    Three missions have been identified by NASA for a Space Shuttle-supplementing Alternate Transportation System (ATS) encompassing combinations of booster vehicles, crew modules, and service modules: (1) to achieve manned access to orbit for Space Station crew rotation every 90 days, (2) the lofting of a logistics module resupplying the Space Station every 180 days, and (3) the simultaneous launch of both crews and logistics to the Space Station. A reentry glider is considered, in conjunction with the Space Shuttle's unmanned cargo version and the Apollo manned capsule, as an important ATS element. The Titan IV/NUS is used as a booster.

  15. Pneumatic Pellet-Transporting System

    NASA Technical Reports Server (NTRS)

    Wood, George; Pugsley, Robert A.

    1992-01-01

    Pneumatic system transports food pellets to confined animals. Flow of air into venturi assembly entrains round pellets, drawing them from reservoir into venturi for transport by airflow. Pneumatic pellet-transporting system includes venturi assembly, which creates flow of air that draws pellets into system.

  16. Arabidopsis IRT2 gene encodes a root-periphery iron transporter.

    PubMed

    Vert, G; Briat, J F; Curie, C

    2001-04-01

    Iron uptake from the soil is a tightly controlled process in plant roots, involving specialized transporters. One such transporter, IRT1, was identified in Arabidopsis thaliana and shown to function as a broad-range metal ion transporter in yeast. Here we report the cloning and characterization of the IRT2 cDNA, a member of the ZIP family of metal transporters, highly similar to IRT1 at the amino-acid level. IRT2 expression in yeast suppresses the growth defect of iron and zinc transport yeast mutants and enhances iron uptake and accumulation. However, unlike IRT1, IRT2 does not transport manganese or cadmium in yeast. IRT2 expression is detected only in roots of A. thaliana plants, and is upregulated by iron deficiency. By fusing the IRT2 promoter to the uidA reporter gene, we show that the IRT2 promoter is mainly active in the external cell layers of the root subapical zone, and therefore provide the first tissue localization of a plant metal transporter. Altogether, these data support a role for the IRT2 transporter in iron and zinc uptake from the soil in response to iron-limited conditions. PMID:11389759

  17. Iron transport in Mycobacterium smegmatis: occurrence of iron-regulated envelope proteins as potential receptors for iron uptake.

    PubMed

    Hall, R M; Sritharan, M; Messenger, A J; Ratledge, C

    1987-08-01

    Cell-envelope fractions were isolated from the rapidly growing saprophyte Mycobacterium smegmatis following growth in glycerol/asparagine medium under both iron-limited (0.02 microgram Fe ml-1) and iron-sufficient (2.0 to 4.0 micrograms Fe ml-1) conditions. Examination of these preparations by SDS-PAGE demonstrated the production of at least four additional proteins when iron was limiting. These iron-regulated envelope proteins (IREPs) were ascribed apparent molecular masses of 180 kDa (protein I), 84 kDa (protein II), 29 kDa (protein III) and 25 kDa (protein IV). All four proteins were present in both cell-wall and membrane preparations but spheroplast preparations were devoid of the 29 kDa protein. Attempts at labelling the proteins with 55FeCl3 or 55Fe-exochelin, the siderophore for iron uptake, were unsuccessful, though this was attributed to the denatured state of the proteins following electrophoresis. Antibodies were raised to each of the four proteins: the one raised to protein III inhibited exochelin-mediated iron uptake into iron-deficiently grown cells by 70% but was ineffective against iron uptake into iron-sufficiently grown cells. As exochelin is taken up into both types of cells by a similar process, protein III may not be a simple receptor for iron uptake though the results imply some function connected with this process. The role of the other IREPs is less certain. PMID:3127539

  18. Functional characterization of LIT1, the Leishmania amazonensis ferrous iron transporter

    PubMed Central

    Jacques, Ismaele; Andrews, Norma W.; Huynh, Chau

    2010-01-01

    Leishmania amazonensis LIT1 was identified based on homology with IRT1, a ferrous iron transporter from Arabidopsis thaliana. Δlit1 Leishmania amazonensis are defective in intracellular replication and lesion formation in vivo, a virulence phenotype attributed to defective intracellular iron acquisition. Here we functionally characterize LIT1, directly demonstrating that it functions as a ferrous iron membrane transporter from the ZIP family. Conserved residues in the predicted transmembrane domains II, IV, V and VII of LIT1 are essential for iron transport in yeast, including histidines that were proposed to function as metal ligands in ZIP transporters. LIT1 also contains two regions within the predicted intracellular loop that are not found in Arabidopsis IRT1. Deletion of region I inhibited LIT1 expression on the surface of Leishmania promastigotes. Deletion of region II did not interfere with LIT1 trafficking to the surface, but abolished its iron transport capacity when expressed in yeast. Mutagenesis revealed two motifs within region II, HGHQH and TPPRDM, that are independently required for iron transport by LIT1. D263 was identified as a key residue required for iron transport within the TPPRDM motif, while P260 and P261 were dispensable. Deletion of proline-rich regions within region I and between regions I and II did not affect iron transport in yeast, but in Leishmania amazonensis were not able to rescue the intracellular growth of Δlit1 parasites, or their ability to form lesions in mice. These results are consistent with a potential role of the unique intracellular loop of LIT1 in intracellular regulation by Leishmania-specific factors. PMID:20025906

  19. Transportation System Concept of Operations

    SciTech Connect

    N. Slater-Thompson

    2006-08-16

    The Nuclear Waste Policy Act of 1982 (NWPA), as amended, authorized the DOE to develop and manage a Federal system for the disposal of SNF and HLW. OCRWM was created to manage acceptance and disposal of SNF and HLW in a manner that protects public health, safety, and the environment; enhances national and energy security; and merits public confidence. This responsibility includes managing the transportation of SNF and HLW from origin sites to the Repository for disposal. The Transportation System Concept of Operations is the core high-level OCRWM document written to describe the Transportation System integrated design and present the vision, mission, and goals for Transportation System operations. By defining the functions, processes, and critical interfaces of this system early in the system development phase, programmatic risks are minimized, system costs are contained, and system operations are better managed, safer, and more secure. This document also facilitates discussions and understanding among parties responsible for the design, development, and operation of the Transportation System. Such understanding is important for the timely development of system requirements and identification of system interfaces. Information provided in the Transportation System Concept of Operations includes: the functions and key components of the Transportation System; system component interactions; flows of information within the system; the general operating sequences; and the internal and external factors affecting transportation operations. The Transportation System Concept of Operations reflects OCRWM's overall waste management system policies and mission objectives, and as such provides a description of the preferred state of system operation. The description of general Transportation System operating functions in the Transportation System Concept of Operations is the first step in the OCRWM systems engineering process, establishing the starting point for the lower level

  20. The Siderocalin/Enterobactin Interaction: A Link between Mammalian Immunity and Bacterial Iron Transport

    SciTech Connect

    Meux, Susan C.

    2008-05-12

    The siderophore enterobactin (Ent) is produced by enteric bacteria to mediate iron uptake. Ent scavenges iron and is taken up by the bacteria as the highly stable ferric complex [Fe{sup III}(Ent)]{sup 3-}. This complex is also a specific target of the mammalian innate immune system protein, Siderocalin (Scn), which acts as an anti-bacterial agent by specifically sequestering siderophores and their ferric complexes during infection. Recent literature suggesting that Scn may also be involved in cellular iron transport has increased the importance of understanding the mechanism of siderophore interception and clearance by Scn; Scn is observed to release iron in acidic endosomes and [Fe{sup III}(Ent)]{sup 3-} is known to undergo a change from catecholate to salicylate coordination in acidic conditions, which is predicted to be sterically incompatible with the Scn binding pocket (also referred to as the calyx). To investigate the interactions between the ferric Ent complex and Scn at different pH values, two recombinant forms of Scn with mutations in three residues lining the calyx were prepared: Scn-W79A/R81A and Scn-Y106F. Binding studies and crystal structures of the Scn-W79A/R81A:[Fe{sup III}(Ent)]{sup 3-} and Scn-Y106F:[Fe{sup III}(Ent)]{sup 3-} complexes confirm that such mutations do not affect the overall conformation of the protein but do weaken significantly its affinity for [Fe{sup III}(Ent)]{sup 3-}. Fluorescence, UV-Vis and EXAFS spectroscopies were used to determine Scn/siderophore dissociation constants and to characterize the coordination mode of iron over a wide pH range, in the presence of both mutant proteins and synthetic salicylate analogs of Ent. While Scn binding hinders salicylate coordination transformation, strong acidification results in the release of iron and degraded siderophore. Iron release may therefore result from a combination of Ent degradation and coordination change.

  1. Role of Iron Uptake Systems in Pseudomonas aeruginosa Virulence and Airway Infection.

    PubMed

    Minandri, Fabrizia; Imperi, Francesco; Frangipani, Emanuela; Bonchi, Carlo; Visaggio, Daniela; Facchini, Marcella; Pasquali, Paolo; Bragonzi, Alessandra; Visca, Paolo

    2016-08-01

    Pseudomonas aeruginosa is a leading cause of hospital-acquired pneumonia and chronic lung infections in cystic fibrosis patients. Iron is essential for bacterial growth, and P. aeruginosa expresses multiple iron uptake systems, whose role in lung infection deserves further investigation. P. aeruginosa Fe(3+) uptake systems include the pyoverdine and pyochelin siderophores and two systems for heme uptake, all of which are dependent on the TonB energy transducer. P. aeruginosa also has the FeoB transporter for Fe(2+) acquisition. To assess the roles of individual iron uptake systems in P. aeruginosa lung infection, single and double deletion mutants were generated in P. aeruginosa PAO1 and characterized in vitro, using iron-poor media and human serum, and in vivo, using a mouse model of lung infection. The iron uptake-null mutant (tonB1 feoB) and the Fe(3+) transport mutant (tonB1) did not grow aerobically under low-iron conditions and were avirulent in the mouse model. Conversely, the wild type and the feoB, hasR phuR (heme uptake), and pchD (pyochelin) mutants grew in vitro and caused 60 to 90% mortality in mice. The pyoverdine mutant (pvdA) and the siderophore-null mutant (pvdA pchD) grew aerobically in iron-poor media but not in human serum, and they caused low mortality in mice (10 to 20%). To differentiate the roles of pyoverdine in iron uptake and virulence regulation, a pvdA fpvR double mutant defective in pyoverdine production but expressing wild-type levels of pyoverdine-regulated virulence factors was generated. Deletion of fpvR in the pvdA background partially restored the lethal phenotype, indicating that pyoverdine contributes to the pathogenesis of P. aeruginosa lung infection by combining iron transport and virulence-inducing capabilities. PMID:27271740

  2. Reactive transport modeling at uranium in situ recovery sites: uncertainties in uranium sorption on iron hydroxides

    USGS Publications Warehouse

    Johnson, Raymond H.; Tutu, Hlanganani

    2013-01-01

    Geochemical changes that can occur down gradient from uranium in situ recovery (ISR) sites are important for various stakeholders to understand when evaluating potential effects on surrounding groundwater quality. If down gradient solid-phase material consists of sandstone with iron hydroxide coatings (no pyrite or organic carbon), sorption of uranium on iron hydroxides can control uranium mobility. Using one-dimensional reactive transport models with PHREEQC, two different geochemical databases, and various geochemical parameters, the uncertainties in uranium sorption on iron hydroxides are evaluated, because these oxidized zones create a greater risk for future uranium transport than fully reduced zones where uranium generally precipitates.

  3. IRT1, an Arabidopsis transporter essential for iron uptake from the soil and for plant growth.

    PubMed

    Vert, Grégory; Grotz, Natasha; Dédaldéchamp, Fabienne; Gaymard, Frédéric; Guerinot, Mary Lou; Briat, Jean-François; Curie, Catherine

    2002-06-01

    Plants are the principal source of iron in most diets, yet iron availability often limits plant growth. In response to iron deficiency, Arabidopsis roots induce the expression of the divalent cation transporter IRT1. Here, we present genetic evidence that IRT1 is essential for the uptake of iron from the soil. An Arabidopsis knockout mutant in IRT1 is chlorotic and has a severe growth defect in soil, leading to death. This defect is rescued by the exogenous application of iron. The mutant plants do not take up iron and fail to accumulate other divalent cations in low-iron conditions. IRT1-green fluorescent protein fusion, transiently expressed in culture cells, localized to the plasma membrane. We also show, through promoter::beta-glucuronidase analysis and in situ hybridization, that IRT1 is expressed in the external cell layers of the root, specifically in response to iron starvation. These results clearly demonstrate that IRT1 is the major transporter responsible for high-affinity metal uptake under iron deficiency. PMID:12084823

  4. IRT1, an Arabidopsis Transporter Essential for Iron Uptake from the Soil and for Plant Growth

    PubMed Central

    Vert, Grégory; Grotz, Natasha; Dédaldéchamp, Fabienne; Gaymard, Frédéric; Guerinot, Mary Lou; Briat, Jean-François; Curie, Catherine

    2002-01-01

    Plants are the principal source of iron in most diets, yet iron availability often limits plant growth. In response to iron deficiency, Arabidopsis roots induce the expression of the divalent cation transporter IRT1. Here, we present genetic evidence that IRT1 is essential for the uptake of iron from the soil. An Arabidopsis knockout mutant in IRT1 is chlorotic and has a severe growth defect in soil, leading to death. This defect is rescued by the exogenous application of iron. The mutant plants do not take up iron and fail to accumulate other divalent cations in low-iron conditions. IRT1–green fluorescent protein fusion, transiently expressed in culture cells, localized to the plasma membrane. We also show, through promoter::β-glucuronidase analysis and in situ hybridization, that IRT1 is expressed in the external cell layers of the root, specifically in response to iron starvation. These results clearly demonstrate that IRT1 is the major transporter responsible for high-affinity metal uptake under iron deficiency. PMID:12084823

  5. Nickel-iron battery system safety

    NASA Technical Reports Server (NTRS)

    Saltat, R. C.

    1984-01-01

    The generated flow rates of gaseous hydrogen and gaseous oxygen from an electrical vehicle nickel-iron battery system were determined and used to evaluate the flame quenching capabilities of several candidate devices to prevent flame propagation within batteries having central watering/venting systems. The battery generated hydrogen and oxygen gases were measured for a complete charge and discharge cycle. The data correlates well with accepted theory during strong overcharge conditions indicating that the measurements are valid for other portions of the cycle. Tests confirm that the gas mixture in the cells is always flammable regardless of the battery status. The literature indicated that a conventional flame arrestor would not be effective over the broad spectrum of gassing conditions presented by a nickel-iron battery. Four different types of protective devices were evaluated. A foam-metal arrestor design was successful in quenching gaseous hydrogen and gaseous oxygen flames, however; the application of this flame arrestor to individual cell or module protection in a battery is problematic. A possible rearrangement of the watering/venting system to accept the partial protection of simple one-way valves is presented which, in combination with the successful foam-metal arrestor as main vent protection, could result in a significant improvement in battery protection.

  6. Nickel-iron battery system safety

    NASA Astrophysics Data System (ADS)

    Saltat, R. C.

    1984-06-01

    The generated flow rates of gaseous hydrogen and gaseous oxygen from an electrical vehicle nickel-iron battery system were determined and used to evaluate the flame quenching capabilities of several candidate devices to prevent flame propagation within batteries having central watering/venting systems. The battery generated hydrogen and oxygen gases were measured for a complete charge and discharge cycle. The data correlates well with accepted theory during strong overcharge conditions indicating that the measurements are valid for other portions of the cycle. Tests confirm that the gas mixture in the cells is always flammable regardless of the battery status. The literature indicated that a conventional flame arrestor would not be effective over the broad spectrum of gassing conditions presented by a nickel-iron battery. Four different types of protective devices were evaluated. A foam-metal arrestor design was successful in quenching gaseous hydrogen and gaseous oxygen flames, however; the application of this flame arrestor to individual cell or module protection in a battery is problematic. A possible rearrangement of the watering/venting system to accept the partial protection of simple one-way valves is presented which, in combination with the successful foam-metal arrestor as main vent protection, could result in a significant improvement in battery protection.

  7. Iron transport in the kidney: implications for physiology and cadmium nephrotoxicity.

    PubMed

    Thévenod, Frank; Wolff, Natascha A

    2016-01-01

    The kidney has recently emerged as an organ with a significant role in systemic iron (Fe) homeostasis. Substantial amounts of Fe are filtered by the kidney, which have to be reabsorbed to prevent Fe deficiency. Accordingly Fe transporters and receptors for protein-bound Fe are expressed in the nephron that may also function as entry pathways for toxic metals, such as cadmium (Cd), by way of "ionic and molecular mimicry". Similarities, but also differences in handling of Cd by these transport routes offer rationales for the propensity of the kidney to develop Cd toxicity. This critical review provides a comprehensive update on Fe transport by the kidney and its relevance for physiology and Cd nephrotoxicity. Based on quantitative considerations, we have also estimated the in vivo relevance of the described transport pathways for physiology and toxicology. Under physiological conditions all segments of the kidney tubules are likely to utilize Fe for cellular Fe requiring processes for metabolic purposes and also to contribute to reabsorption of free and bound forms of Fe into the circulation. But Cd entering tubule cells disrupts metabolic pathways and is unable to exit. Furthermore, our quantitative analyses contest established models linking chronic Cd nephrotoxicity to proximal tubular uptake of metallothionein-bound Cd. Hence, Fe transport by the kidney may be beneficial by preventing losses from the body. But increased uptake of Fe or Cd that cannot exit tubule cells may lead to kidney injury, and Fe deficiency may facilitate renal Cd uptake. PMID:26485516

  8. Role of clay minerals in the transportation of iron

    USGS Publications Warehouse

    Carroll, D.

    1958-01-01

    The clay minerals have iron associated with them in several ways: 1. (1) as an essential constituent 2. (2) as a minor constituent within the crystal lattice where it is in isomorphous substitution and 3. (3) as iron oxide on the surface of the mineral platelets. Nontronite, "hydromica," some chlorites, vermiculite, glauconite and chamosite contain iron as an essential constituent. Kaolinite and halloysite have no site within the lattice for iron, but in certain environments iron oxide (goethite or hematite) is intimately associated as a coating on the micelles. Analyses of clay minerals show that the content of Fe2O3 varies: 29 per cent (nontronite), 7??3 per cent (griffithite), 4.5 per cent ("hydromica"), 5.5 per cent (chlorite), 4 per cent (vermiculite) and 18 per cent (glauconite). The FeO content is: 40 per cent (chamosite), 7.8 per cent (griffithite), 1-2 per cent ("hydromica"), 3 per cent (glauconite) and 2 per cent (chlorite). The iron associated with the clay minerals remains stable in the environment in which the minerals occur, but if either pH or Eh or both are changed the iron may be affected. Change of environment will cause: 1. (1) removal of iron by reduction of Fe3+ to Fe2+; 2. (2) ion-exchange reactions; 3. (3) instability of the crystal lattice. Experiments using bacterial activity to produce reducing conditions with kaolinite and halloysite coated with iron oxides and with nontronite in which ferric iron is in the octahedral position within the lattice showed that ferric oxide is removed at Eh +0??215 in fresh water and at Eh +0.098 in sea water. Hematite, goethite, and indefinite iron oxides were removed at different rates. Red ferric oxides were changed to black indefinite noncrystalline ferrous sulphide at Eh -0.020 but reverted to ferric oxide under oxidizing conditions. Nontronite turned bright green under reducing conditions and some of the ferrous iron remained within the lattice on a return to oxidizing conditions. Bacterial activity

  9. Enzymatic Hydrolysis of Trilactone Siderophores: Where Chiral Recognition Occurs in Enterobactin and Bacillibactin Iron Transport1

    PubMed Central

    Abergel, Rebecca J.; Zawadzka, Anna M.; Hoette, Trisha M.; Raymond, Kenneth N.

    2009-01-01

    Bacillibactin and enterobactin are hexadentate catecholate siderophores produced by bacteria upon iron limitation to scavenge ferric ion and seem to be the ultimate siderophores of their two respective domains: Gram-positive and Gram-negative. Iron acquisition mediated by these trilactone-based ligands necessitates enzymatic hydrolysis of the scaffold for successful intracellular iron delivery. The esterases BesA and Fes hydrolyze bacillibactin and enterobactin, respectively, as well as the corresponding iron complexes. Bacillibactin binds iron through three 2,3-catecholamide moieties linked to a tri-threonine scaffold via glycine spacers, whereas in enterobactin the iron-binding moieties are directly attached to a tri-l-serine backbone; although apparently minor, these structural differences result in markedly different iron coordination properties and iron transport behavior. Comparison of the solution thermodynamic and circular dichroism properties of bacillibactin, enterobactin and the synthetic analogs d-enterobactin, SERGlyCAM and d-SERGlyCAM has determined the role of each different feature in the siderophores' molecular structures in ferric complex stability and metal chirality. While opposite metal chiralities in the different complexes did not affect transport and incorporation in Bacillus subtilis, ferric complexes formed with the various siderophores did not systematically promote growth of the bacteria. The bacillibactin esterase BesA is less specific than the enterobactin esterase Fes; BesA can hydrolyze the trilactones of both siderophores, while only the tri-l-serine trilactone is a substrate of Fes. Both enzymes are stereospecific and cannot cleave tri-d-serine lactones. These data provide a complete picture of the microbial iron transport mediated by these two siderophores, from initial recognition and transport to intracellular iron release. PMID:19673474

  10. Helium, Iron and Electron Particle Transport and Energy Transport Studies on the TFTR Tokamak

    DOE R&D Accomplishments Database

    Synakowski, E. J.; Efthimion, P. C.; Rewoldt, G.; Stratton, B. C.; Tang, W. M.; Grek, B.; Hill, K. W.; Hulse, R. A.; Johnson, D .W.; Mansfield, D. K.; McCune, D.; Mikkelsen, D. R.; Park, H. K.; Ramsey, A. T.; Redi, M. H.; Scott, S. D.; Taylor, G.; Timberlake, J.; Zarnstorff, M. C. (Princeton Univ., NJ (United States). Plasma Physics Lab.); Kissick, M. W. (Wisconsin Univ., Madison, WI (United States))

    1993-03-01

    Results from helium, iron, and electron transport on TFTR in L-mode and Supershot deuterium plasmas with the same toroidal field, plasma current, and neutral beam heating power are presented. They are compared to results from thermal transport analysis based on power balance. Particle diffusivities and thermal conductivities are radially hollow and larger than neoclassical values, except possibly near the magnetic axis. The ion channel dominates over the electron channel in both particle and thermal diffusion. A peaked helium profile, supported by inward convection that is stronger than predicted by neoclassical theory, is measured in the Supershot The helium profile shape is consistent with predictions from quasilinear electrostatic drift-wave theory. While the perturbative particle diffusion coefficients of all three species are similar in the Supershot, differences are found in the L-Mode. Quasilinear theory calculations of the ratios of impurity diffusivities are in good accord with measurements. Theory estimates indicate that the ion heat flux should be larger than the electron heat flux, consistent with power balance analysis. However, theoretical values of the ratio of the ion to electron heat flux can be more than a factor of three larger than experimental values. A correlation between helium diffusion and ion thermal transport is observed and has favorable implications for sustained ignition of a tokamak fusion reactor.

  11. Helium, iron and electron particle transport and energy transport studies on the TFTR tokamak

    SciTech Connect

    Synakowski, E.J.; Efthimion, P.C.; Rewoldt, G.; Stratton, B.C.; Tang, W.M.; Grek, B.; Hill, K.W.; Hulse, R.A.; Johnson, D.W.; Mansfield, D.K.; McCune, D.; Mikkelsen, D.R.; Park, H.K.; Ramsey, A.T.; Redi, M.H.; Scott, S.D.; Taylor, G.; Timberlake, J.; Zarnstorff, M.C.; Kissick, M.W.

    1993-03-01

    Results from helium, iron, and electron transport on TFTR in L-mode and Supershot deuterium plasmas with the same toroidal field, plasma current, and neutral beam heating power are presented. They are compared to results from thermal transport analysis based on power balance. Particle diffusivities and thermal conductivities are radially hollow and larger than neoclassical values, except possibly near the magnetic axis. The ion channel dominates over the electron channel in both particle and thermal diffusion. A peaked helium profile, supported by inward convection that is stronger than predicted by neoclassical theory, is measured in the Supershot The helium profile shape is consistent with predictions from quasilinear electrostatic drift-wave theory. While the perturbative particle diffusion coefficients of all three species are similar in the Supershot, differences are found in the L-Mode. Quasilinear theory calculations of the ratios of impurity diffusivities are in good accord with measurements. Theory estimates indicate that the ion heat flux should be larger than the electron heat flux, consistent with power balance analysis. However, theoretical values of the ratio of the ion to electron heat flux can be more than a factor of three larger than experimental values. A correlation between helium diffusion and ion thermal transport is observed and has favorable implications for sustained ignition of a tokamak fusion reactor.

  12. Iron transport across the blood-brain barrier; Development, neurovascular regulation and cerebral amyloid angiopathy

    PubMed Central

    McCarthy, Ryan C; Kosman, Daniel J

    2014-01-01

    There are two barriers for iron entry into the brain: 1) the brain-cerebrospinal fluid (CSF) barrier and 2) the blood-brain barrier (BBB). Here, we review the literature on developmental iron accumulation by the brain, focusing on the transport of iron through the brain microvascular endothelial cells (BMVEC) of the BBB. We review the iron trafficking proteins which may be involved in the iron flux across BMVEC and discuss the plausible mechanisms of BMVEC iron uptake and efflux. We suggest a model for how BMVEC iron uptake and efflux are regulated and a mechanism by which the majority of iron is trafficked across the developing BBB under the direct guidance of neighboring astrocytes. Thus, we place brain iron uptake in the context of the neurovascular unit of the adult brain. Last, we propose that BMVEC iron is involved in the aggregation of amyloid-β peptides leading to the progression of cerebral amyloid angiopathy which often occurs prior to dementia and the onset of Alzheimer's disease. PMID:25355056

  13. Iron

    MedlinePlus

    Iron is a mineral that our bodies need for many functions. For example, iron is part of hemoglobin, a protein which carries ... It helps our muscles store and use oxygen. Iron is also part of many other proteins and ...

  14. Evaluation of the effect of divalent metal transporter 1 gene polymorphism on blood iron, lead and cadmium levels

    SciTech Connect

    Kayaaltı, Zeliha Akyüzlü, Dilek Kaya; Söylemezoğlu, Tülin

    2015-02-15

    Divalent metal transporter 1 (DMT1), a member of the proton-coupled metal ion transporter family, mediates transport of ferrous iron from the lumen of the intestine into the enterocyte and export of iron from endocytic vesicles. It has an affinity not only for iron but also for other divalent cations including manganese, cobalt, nickel, cadmium, lead, copper, and zinc. DMT1 is encoded by the SLC11a2 gene that is located on chromosome 12q13 in humans and express four major mammalian isoforms (1A/+IRE, 1A/-IRE, 2/+IRE and 2/-IRE). Mutations or polymorphisms of DMT1 gene may have an impact on human health by disturbing metal trafficking. To study the possible association of DMT1 gene with the blood levels of some divalent cations such as iron, lead and cadmium, a single nucleotide polymorphism (SNP) (IVS4+44C/A) in DMT1 gene was investigated in 486 unrelated and healthy individuals in a Turkish population by method of polymerase chain reaction–restriction fragment length polymorphism (PCR–RFLP). The genotype frequencies were found as 49.8% homozygote typical (CC), 38.3% heterozygote (CA) and 11.9% homozygote atypical (AA). Metal levels were analyzed by dual atomic absorption spectrometer system and the average levels of iron, lead and cadmium in the blood samples were 446.01±81.87 ppm, 35.59±17.72 ppb and 1.25±0.87 ppb, respectively. Individuals with the CC genotype had higher blood iron, lead and cadmium levels than those with AA and CA genotypes. Highly statistically significant associations were detected between IVS4+44 C/A polymorphism in the DMT1 gene and iron and lead levels (p=0.001 and p=0.036, respectively), but no association was found with cadmium level (p=0.344). This study suggested that DMT1 IVS4+44 C/A polymorphism is associated with inter-individual variations in blood iron, lead and cadmium levels. - Highlights: • DMT1 IVS4+44 C/A polymorphism is associated with inter-individual variations in blood iron, cadmium and lead levels.

  15. Transport of carbon colloid supported nanoscale zero-valent iron in saturated porous media

    NASA Astrophysics Data System (ADS)

    Busch, Jan; Meißner, Tobias; Potthoff, Annegret; Oswald, Sascha E.

    2014-08-01

    Injection of nanoscale zero-valent iron (nZVI) has recently gained great interest as emerging technology for in-situ remediation of chlorinated organic compounds from groundwater systems. Zero-valent iron (ZVI) is able to reduce organic compounds and to render it to less harmful substances. The use of nanoscale particles instead of granular or microscale particles can increase dechlorination rates by orders of magnitude due to its high surface area. However, classical nZVI appears to be hampered in its environmental application by its limited mobility. One approach is colloid supported transport of nZVI, where the nZVI gets transported by a mobile colloid. In this study transport properties of activated carbon colloid supported nZVI (c-nZVI; d50 = 2.4 μm) are investigated in column tests using columns of 40 cm length, which were filled with porous media. A suspension was pumped through the column under different physicochemical conditions (addition of a polyanionic stabilizer and changes in pH and ionic strength). Highest observed breakthrough was 62% of the injected concentration in glass beads with addition of stabilizer. Addition of mono- and bivalent salt, e.g. more than 0.5 mM/L CaCl2, can decrease mobility and changes in pH to values below six can inhibit mobility at all. Measurements of colloid sizes and zeta potentials show changes in the mean particle size by a factor of ten and an increase of zeta potential from - 62 mV to - 80 mV during the transport experiment. However, results suggest potential applicability of c-nZVI under field conditions.

  16. MASS TRANSPORT EFFECTS ON THE KINETICS OF NITROBENZENE REDUCTION BY IRON METAL. (R827117)

    EPA Science Inventory

    To evaluate the importance of external mass transport on the overall rates of
    contaminant reduction by iron metal (Fe0), we have compared measured
    rates of surface reaction for nitrobenzene (ArNO2) to estimated rates
    of external mass transport...

  17. Use of Electrophoresis for Transporting Nano-Iron in Porous Media

    EPA Science Inventory

    Research was conducted to evaluate if electrophoresis could transport surface stabilized nanoscale zero-valent iron (nZVI) through fine grained sand with the intent of remediating a contaminant in situ. The experimental procedure involved determining the transport rates of poly...

  18. Getting to the root of plant iron uptake and cell-cell transport: Polarity matters!

    PubMed Central

    Dubeaux, Guillaume; Zelazny, Enric; Vert, Grégory

    2015-01-01

    Plasma membrane proteins play pivotal roles in mediating responses to endogenous and environmental cues. Regulation of membrane protein levels and establishment of polarity are fundamental for many cellular processes. In plants, IRON-REGULATED TRANSPORTER 1 (IRT1) is the major root iron transporter but is also responsible for the absorption of other divalent metals such as manganese, zinc and cobalt. We recently uncovered that IRT1 is polarly localized to the outer plasma membrane domain of plant root epidermal cells upon depletion of its secondary metal substrates. The endosome-recruited FYVE1 protein interacts with IRT1 in the endocytic pathway and plays a crucial role in the establishment of IRT1 polarity, likely through its recycling to the cell surface. Our work sheds light on the mechanisms of radial transport of nutrients across the different cell types of plant roots toward the vascular tissues and raises interesting parallel with iron transport in mammals. PMID:26479146

  19. Genetic and Functional Analyses of the Actinobacillus actinomycetemcomitans AfeABCD Siderophore-Independent Iron Acquisition System

    PubMed Central

    Rhodes, Eric R.; Tomaras, Andrew P.; McGillivary, Glen; Connerly, Pamela L.; Actis, Luis A.

    2005-01-01

    The Actinobacillus actinomycetemcomitans afeABCD iron transport system, the expression of which is controlled by iron and Fur, was identified in three different isolates. The protein products of this locus are related to bacterial ABC transporters involved in metal transport. Transformation of the Escherichia coli 1017 iron acquisition mutant with a plasmid harboring afeABCD promoted cell growth under iron-chelated conditions. However, insertion disruption of each of the afeABCD coding regions abolished this growth-relieving effect. The replacement of the parental afeA allele with the derivative afeA::EZ::TN drastically reduced the ability of A. actinomycetemcomitans cells to grow under iron-chelated conditions. PMID:15908408

  20. Sources, transport and deposition of iron in the global atmosphere

    NASA Astrophysics Data System (ADS)

    Wang, R.; Balkanski, Y.; Boucher, O.; Bopp, L.; Chappell, A.; Ciais, P.; Hauglustaine, D.; Peñuelas, J.; Tao, S.

    2015-03-01

    Atmospheric deposition of iron (Fe) plays an important role in controlling oceanic primary productivity. However, the sources of Fe in the atmosphere are not well understood. In particular, the combustion sources of Fe and their deposition over oceans are not accounted for in current biogeochemical models of the carbon cycle. Here we used a mass-balance method to estimate the emissions of Fe from the combustion of fossil fuels and biomass by accounting for the Fe contents in fuel and the partitioning of Fe during combustion. The emissions of Fe attached to aerosols from combustion sources were estimated by particle size, and their uncertainties were quantified by a Monte Carlo simulation. The emissions of Fe from mineral sources were estimated using the latest soil mineralogical database to date. As a result, the total Fe emissions from combustion averaged for 1960-2007 were estimated to be 5.1 Tg yr-1 (90% confidence of 2.2 to 11.5). Of these emissions, 2, 33 and 65% were emitted in particles <1 μm (PM1), 1-10 μm (PM1-10), and >10 μm (PM>10), respectively, compared to total Fe emissions from mineral sources of 41.0 Tg yr-1. For combustion sources, different temporal trends were found in fine and medium-to-coarse particles, with a notable increase in Fe emissions in PM1 and PM1-10 since 2000 due to a rapid increase from motor vehicles. These emissions have been introduced in a global 3-D transport model run at a spatial resolution of of 0.94° latitude by 1.28° longitude to evaluate our estimation of Fe emissions. The modelled Fe concentrations were compared to measurements at 825 sampling stations. The deviation between modelled and observed Fe concentrations attached to aerosols at the surface was within a factor of two at most sampling stations, and the deviation was within a factor of 1.5 at sampling stations dominated by combustion sources. We analyzed the relative contribution of combustion sources to total Fe concentrations over different regions of the

  1. Sources, transport and deposition of iron in the global atmosphere

    NASA Astrophysics Data System (ADS)

    Wang, R.; Balkanski, Y.; Boucher, O.; Bopp, L.; Chappell, A.; Ciais, P.; Hauglustaine, D.; Peñuelas, J.; Tao, S.

    2015-06-01

    Atmospheric deposition of iron (Fe) plays an important role in controlling oceanic primary productivity. However, the sources of Fe in the atmosphere are not well understood. In particular, the combustion sources of Fe and the subsequent deposition to the oceans have been accounted for in only few ocean biogeochemical models of the carbon cycle. Here we used a mass-balance method to estimate the emissions of Fe from the combustion of fossil fuels and biomass by accounting for the Fe contents in fuel and the partitioning of Fe during combustion. The emissions of Fe attached to aerosols from combustion sources were estimated by particle size, and their uncertainties were quantified by a Monte Carlo simulation. The emissions of Fe from mineral sources were estimated using the latest soil mineralogical database to date. As a result, the total Fe emissions from combustion averaged for 1960-2007 were estimated to be 5.3 Tg yr-1 (90% confidence of 2.3 to 12.1). Of these emissions, 1, 27 and 72% were emitted in particles < 1 μm (PM1), 1-10 μm (PM1-10), and > 10 μm (PM> 10), respectively, compared to a total Fe emission from mineral dust of 41.0 Tg yr-1 in a log-normal distribution with a mass median diameter of 2.5 μm and a geometric standard deviation of 2. For combustion sources, different temporal trends were found in fine and medium-to-coarse particles, with a notable increase in Fe emissions in PM1 since 2000 due to an increase in Fe emission from motor vehicles (from 0.008 to 0.0103 Tg yr-1 in 2000 and 2007, respectively). These emissions have been introduced in a global 3-D transport model run at a spatial resolution of 0.94° latitude by 1.28° longitude to evaluate our estimation of Fe emissions. The modelled Fe concentrations as monthly means were compared with the monthly (57 sites) or daily (768 sites) measured concentrations at a total of 825 sampling stations. The deviation between modelled and observed Fe concentrations attached to aerosols at the

  2. Ndfip2 is a potential regulator of the iron transporter DMT1 in the liver

    PubMed Central

    Foot, Natalie J.; Gembus, Kelly M.; Mackenzie, Kimberly; Kumar, Sharad

    2016-01-01

    The regulation of divalent metal ion transporter DMT1, the primary non-heme iron importer in mammals, is critical for maintaining iron homeostasis. Previously we identified ubiquitin-dependent regulation of DMT1 involving the Nedd4 family of ubiquitin ligases and the Ndfip1 and Ndfip2 adaptors. We also established the in vivo function of Ndfip1 in the regulation of DMT1 in the duodenum of mice. Here we have studied the function of Ndfip2 using Ndfip2-deficient mice. The DMT1 protein levels in the duodenum were comparable in wild type and Ndfip2−/− mice, as was the transport activity of isolated enterocytes. A complete blood examination showed no significant differences between wild type and Ndfip2−/− mice in any of the hematological parameters measured. However, when fed a low iron diet, female Ndfip2−/− mice showed a decrease in liver iron content, although they maintained normal serum iron levels and transferrin saturation, compared to wild type female mice that showed a reduction in serum iron and transferrin saturation. Ndfip2−/− female mice also showed an increase in DMT1 expression in the liver, with no change in male mice. We suggest that Ndfip2 controls DMT1 in the liver with female mice showing a greater response to altered dietary iron than the male mice. PMID:27048792

  3. 21 CFR 862.1415 - Iron-binding capacity test system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Iron-binding capacity test system. 862.1415... Systems § 862.1415 Iron-binding capacity test system. (a) Identification. An iron-binding capacity test system is a device intended to measure iron-binding capacity in serum. Iron-binding capacity...

  4. 21 CFR 862.1415 - Iron-binding capacity test system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Iron-binding capacity test system. 862.1415... Systems § 862.1415 Iron-binding capacity test system. (a) Identification. An iron-binding capacity test system is a device intended to measure iron-binding capacity in serum. Iron-binding capacity...

  5. 21 CFR 862.1415 - Iron-binding capacity test system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Iron-binding capacity test system. 862.1415... Systems § 862.1415 Iron-binding capacity test system. (a) Identification. An iron-binding capacity test system is a device intended to measure iron-binding capacity in serum. Iron-binding capacity...

  6. 21 CFR 862.1415 - Iron-binding capacity test system.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Iron-binding capacity test system. 862.1415... Systems § 862.1415 Iron-binding capacity test system. (a) Identification. An iron-binding capacity test system is a device intended to measure iron-binding capacity in serum. Iron-binding capacity...

  7. 21 CFR 862.1415 - Iron-binding capacity test system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Iron-binding capacity test system. 862.1415... Systems § 862.1415 Iron-binding capacity test system. (a) Identification. An iron-binding capacity test system is a device intended to measure iron-binding capacity in serum. Iron-binding capacity...

  8. Effects of electron transport inhibitors and uncouplers on the oxidation of ferrous iron and compounds interacting with ferric iron in Acidithiobacillus ferrooxidans.

    PubMed

    Chen, Yongqiang; Suzuki, Isamu

    2005-08-01

    Oxidation of Fe2+, ascorbic acid, propyl gallate, tiron, L-cysteine, and glutathione by Acidithiobacillus ferrooxidans was studied with respect to the effect of electron transport inhibitors and uncouplers on the rate of oxidation. All the oxidations were sensitive to inhibitors of cytochrome c oxidase, KCN, and NaN3. They were also partially inhibited by inhibitors of complex I and complex III of the electron transport system. Uncouplers at low concentrations stimulated the oxidation and inhibited it at higher concentrations. The oxidation rates of Fe2+ and L-cysteine inhibited by complex I and complex III inhibitors (amytal, rotenone, antimycin A, myxothiazol, and HQNO) were stimulated more extensively by uncouplers than the control rates. Atabrine, a flavin antagonist, was an exception, and atabrine-inhibited oxidation activities of all these compounds were further inhibited by uncouplers. A model for the electron transport pathways of A. ferrooxidans is proposed to account for these results. In the model these organic substrates reduce ferric iron on the surface of cells to ferrous iron, which is oxidized back to ferric iron through the Fe2+ oxidation pathway, leading to cytochrome oxidase to O2. Some of electrons enter the uphill (energy-requiring) electron transport pathway to reduce NAD+. Uncouplers at low concentrations stimulate Fe2+ oxidation by stimulating cytochrome oxidase by uncoupling. Higher concentrations lower deltap to the level insufficient to overcome the potentially uphill reaction at rusticyanin-cytochrome c4. Inhibition of uphill reactions at complex I and complex III leads to deltap accumulation and inhibition of cytochrome oxidase. Uncouplers remove the inhibition of deltap and stimulate the oxidation. Atabrine inhibition is not released by uncouplers, which implies a possibility of atabrine inhibition at a site other than complex I, but a site somehow involved in the Fe2+ oxidation pathway. PMID:16234867

  9. Iron stress restricts photosynthetic intersystem electron transport in Synechococcus sp. PCC 7942.

    PubMed

    Ivanov, A G; Park, Y I; Miskiewicz, E; Raven, J A; Huner, N P; Oquist, G

    2000-11-24

    Although exposure of Synechococcus sp. PCC 7942 to iron stress induced the accumulation of the isiA gene product (CP43') compared with non-stressed controls, immunodetection of the N-terminus of cytochrome (Cyt) f indicated that iron stress not only reduced the content of the 40 kDa, heme-binding, Cyt f polypeptide by 32% but it also specifically induced the accumulation of a new, 23 kDa, non-heme-binding, putative Cyt f polypeptide. Concomitantly, iron stress restricted intersystem electron transport based on the in vivo reduction of P700(+), monitored as delta A(820)/A(820) in the presence and absence of electron transport inhibitors, as well as the inhibition of the Emerson enhancement effect on O(2) evolution. However, iron stress appeared to be associated with enhanced rates of PS I cyclic electron transport, low rates of PS I-driven photoreduction of NADP(+) but comparable rates for PS II+PS I photoreduction of NADP(+) relative to controls. We hypothesize that Synechococcus sp. PCC 7942 exhibits a dynamic capacity to uncouple PS II and PS I electron transport, which may allow for the higher than expected growth rates observed during iron stress. PMID:11094162

  10. Effects of iron overload on the immune system.

    PubMed

    Walker, E M; Walker, S M

    2000-10-01

    Iron and its binding proteins have immunoregulatory properties, and shifting of immunoregulatory balances by iron excess or deficiency may produce severe, deleterious physiological effects. Effects of iron overload include decreased antibody-mediated and mitogen-stimulated phagocytosis by monocytes and macrophages, alterations in T-lymphocyte subsets, and modification of lymphocyte distribution in different compartments of the immune system. The importance of iron in regulating the expression of T-lymphocyte cell surface markers, influencing the expansion of different T-cell subsets, and affecting immune cell functions can be demonstrated in vitro and in vivo. The poor ability of lymphocytes to sequester excess iron in ferritin may help to explain the immune system abnormalities in iron-overloaded patients. Iron overload as seen in hereditary hemochromatosis patients enhances suppressor T-cell (CD8) numbers and activity, decreases the proliferative capacity, numbers, and activity of helper T cells (CD4) with increases in CD8/CD4 ratios, impairs the generation of cytotoxic T cells, and alters immunoglobulin secretion when compared to treated hereditary hemochromatosis patients or controls. A correlation has recently been found between low CD8+ lymphocyte numbers, liver damage associated with HCV positivity, and severity of iron overload in beta-thalassemia major patients. Iron overload, with its associated increases of serum iron levels and transferrin saturation, may cause a poor response to interferon therapy. Iron overload with hyperferremia is associated with suppressed functions of the complement system (classic or alternative types). High plasma ferritin content in patients with chronic, diffuse diseases of the liver (cirrhosis, chronic hepatitis), beta-thalassemia major, dyserythropoiesis, and hereditary hemochromatosis may induce the development of anti-ferritin antibodies with the production of circulating immune complexes. Increased body stores of iron in

  11. Droplet transport system and methods

    NASA Technical Reports Server (NTRS)

    Neitzel, G. Paul (Inventor)

    2010-01-01

    Embodiments of droplet transport systems and methods are disclosed for levitating and transporting single or encapsulated droplets using thermocapillary convection. One method embodiment, among others comprises providing a droplet of a first liquid; and applying thermocapillary convection to the droplet to levitate and move the droplet.

  12. 21 CFR 862.1410 - Iron (non-heme) test system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Iron (non-heme) test system. 862.1410 Section 862....1410 Iron (non-heme) test system. (a) Identification. An iron (non-heme) test system is a device intended to measure iron (non-heme) in serum and plasma. Iron (non-heme) measurements are used in...

  13. 21 CFR 862.1410 - Iron (non-heme) test system.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Iron (non-heme) test system. 862.1410 Section 862....1410 Iron (non-heme) test system. (a) Identification. An iron (non-heme) test system is a device intended to measure iron (non-heme) in serum and plasma. Iron (non-heme) measurements are used in...

  14. 21 CFR 862.1410 - Iron (non-heme) test system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Iron (non-heme) test system. 862.1410 Section 862....1410 Iron (non-heme) test system. (a) Identification. An iron (non-heme) test system is a device intended to measure iron (non-heme) in serum and plasma. Iron (non-heme) measurements are used in...

  15. 21 CFR 862.1410 - Iron (non-heme) test system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Iron (non-heme) test system. 862.1410 Section 862....1410 Iron (non-heme) test system. (a) Identification. An iron (non-heme) test system is a device intended to measure iron (non-heme) in serum and plasma. Iron (non-heme) measurements are used in...

  16. 21 CFR 862.1410 - Iron (non-heme) test system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Iron (non-heme) test system. 862.1410 Section 862....1410 Iron (non-heme) test system. (a) Identification. An iron (non-heme) test system is a device intended to measure iron (non-heme) in serum and plasma. Iron (non-heme) measurements are used in...

  17. IRON

    EPA Science Inventory

    The document surveys the effects of organic and inorganic iron that are relevant to humans and their environment. The biology and chemistry of iron are complex and only partially understood. Iron participates in oxidation reduction processes that not only affect its geochemical m...

  18. A Trypanosomatid Iron Transporter that Regulates Mitochondrial Function Is Required for Leishmania amazonensis Virulence

    PubMed Central

    Mittra, Bidyottam; Laranjeira-Silva, Maria Fernanda; Perrone Bezerra de Menezes, Juliana; Jensen, Jennifer; Michailowsky, Vladimir; Andrews, Norma W.

    2016-01-01

    Iron, an essential co-factor of respiratory chain proteins, is critical for mitochondrial function and maintenance of its redox balance. We previously reported a role for iron uptake in differentiation of Leishmania amazonensis into virulent amastigotes, by a mechanism that involves reactive oxygen species (ROS) production and is independent of the classical pH and temperature cues. Iron import into mitochondria was proposed to be essential for this process, but evidence supporting this hypothesis was lacking because the Leishmania mitochondrial iron transporter was unknown. Here we describe MIT1, a homolog of the mitochondrial iron importer genes mrs3 (yeast) and mitoferrin-1 (human) that is highly conserved among trypanosomatids. MIT1 expression was essential for the survival of Trypanosoma brucei procyclic but not bloodstream forms, which lack functional respiratory complexes. L. amazonensis LMIT1 null mutants could not be generated, suggesting that this mitochondrial iron importer is essential for promastigote viability. Promastigotes lacking one LMIT1 allele (LMIT1/Δlmit1) showed growth defects and were more susceptible to ROS toxicity, consistent with the role of iron as the essential co-factor of trypanosomatid mitochondrial superoxide dismutases. LMIT1/Δlmit1 metacyclic promastigotes were unable to replicate as intracellular amastigotes after infecting macrophages or cause cutaneous lesions in mice. When induced to differentiate axenically into amastigotes, LMIT1/Δlmit1 showed strong defects in iron content and function of mitochondria, were unable to upregulate the ROS-regulatory enzyme FeSOD, and showed mitochondrial changes suggestive of redox imbalance. Our results demonstrate the importance of mitochondrial iron uptake in trypanosomatid parasites, and highlight the role of LMIT1 in the iron-regulated process that orchestrates differentiation of L. amazonensis into infective amastigotes. PMID:26741360

  19. A Trypanosomatid Iron Transporter that Regulates Mitochondrial Function Is Required for Leishmania amazonensis Virulence.

    PubMed

    Mittra, Bidyottam; Laranjeira-Silva, Maria Fernanda; Perrone Bezerra de Menezes, Juliana; Jensen, Jennifer; Michailowsky, Vladimir; Andrews, Norma W

    2016-01-01

    Iron, an essential co-factor of respiratory chain proteins, is critical for mitochondrial function and maintenance of its redox balance. We previously reported a role for iron uptake in differentiation of Leishmania amazonensis into virulent amastigotes, by a mechanism that involves reactive oxygen species (ROS) production and is independent of the classical pH and temperature cues. Iron import into mitochondria was proposed to be essential for this process, but evidence supporting this hypothesis was lacking because the Leishmania mitochondrial iron transporter was unknown. Here we describe MIT1, a homolog of the mitochondrial iron importer genes mrs3 (yeast) and mitoferrin-1 (human) that is highly conserved among trypanosomatids. MIT1 expression was essential for the survival of Trypanosoma brucei procyclic but not bloodstream forms, which lack functional respiratory complexes. L. amazonensis LMIT1 null mutants could not be generated, suggesting that this mitochondrial iron importer is essential for promastigote viability. Promastigotes lacking one LMIT1 allele (LMIT1/Δlmit1) showed growth defects and were more susceptible to ROS toxicity, consistent with the role of iron as the essential co-factor of trypanosomatid mitochondrial superoxide dismutases. LMIT1/Δlmit1 metacyclic promastigotes were unable to replicate as intracellular amastigotes after infecting macrophages or cause cutaneous lesions in mice. When induced to differentiate axenically into amastigotes, LMIT1/Δlmit1 showed strong defects in iron content and function of mitochondria, were unable to upregulate the ROS-regulatory enzyme FeSOD, and showed mitochondrial changes suggestive of redox imbalance. Our results demonstrate the importance of mitochondrial iron uptake in trypanosomatid parasites, and highlight the role of LMIT1 in the iron-regulated process that orchestrates differentiation of L. amazonensis into infective amastigotes. PMID:26741360

  20. Regulation of iron transport related genes by boron in the marine bacterium Marinobacter algicola DG893.

    PubMed

    Romano, Ariel; Trimble, Lyndsay; Hobusch, Ashtian R; Schroeder, Kristine J; Amin, Shady A; Hartnett, Andrej D; Barker, Ryan A; Crumbliss, Alvin L; Carrano, Carl J

    2013-08-01

    While there has been extensive interest in the use of boron isotope ratios as a surrogate of pH in paleoclimate studies in the context of climate change-related questions, the high (0.4 mM) concentration and the depth-independent (conservative or non-nutrient-like) concentration profile of this element have led to boron being neglected as a potentially biologically relevant element in the modern ocean. Here we report that boron affects the expression of a number of protein and genes in the "algal-associated" Gram-negative marine bacterium Marinobacter algicola DG893. Most intriguingly, a number of these proteins and genes are related to iron uptake. In a recent separate publication we have shown that boron regulates one such iron transport related protein, i.e. the periplasmic iron binding protein FbpA via a direct interaction of the metalloid with this protein. Here we show that a number of other iron uptake related genes are also affected by boron but in the opposite way i.e. they are up-regulated. We propose that the differential effect of boron on FbpA expression relative to other iron transport related genes is a result of an interaction between boron and the global iron regulatory protein Fur. PMID:23775459

  1. 49 CFR 230.91 - Chafing irons.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Chafing irons. 230.91 Section 230.91 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Tenders Draw Gear and Draft Systems § 230.91 Chafing irons. Chafing irons that permit proper curving...

  2. 49 CFR 230.91 - Chafing irons.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Chafing irons. 230.91 Section 230.91 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Tenders Draw Gear and Draft Systems § 230.91 Chafing irons. Chafing irons that permit proper curving...

  3. 49 CFR 230.91 - Chafing irons.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Chafing irons. 230.91 Section 230.91 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Tenders Draw Gear and Draft Systems § 230.91 Chafing irons. Chafing irons that permit proper curving...

  4. 49 CFR 230.91 - Chafing irons.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Chafing irons. 230.91 Section 230.91 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Tenders Draw Gear and Draft Systems § 230.91 Chafing irons. Chafing irons that permit proper curving...

  5. 49 CFR 230.91 - Chafing irons.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Chafing irons. 230.91 Section 230.91 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Tenders Draw Gear and Draft Systems § 230.91 Chafing irons. Chafing irons that permit proper curving...

  6. Changes of ferrous iron and its transporters after intracerebral hemorrhage in rats

    PubMed Central

    Wang, Gaiqing; Shao, Anwen; Hu, Weimin; Xue, Fang; Zhao, Hongping; Jin, Xiaojie; Li, Guanglai; Sun, Zhitang; Wang, Li

    2015-01-01

    Objective: Ferrous iron is a major source inducing oxidative stress after intracerebral hemorrhage (ICH). Divalent metal transporter1 (DMT1) is the important and well-known plasma membrane transport protein which was proved to be involved in the transport of free ferrous iron in mammals. Ferroportin 1 (FPN1) is the unique exporter of ferrous iron from mammalian cells. The role of DMT1 and FPN1 in brain after ICH is still not elucidated. Therefore, we measure the expression of DMT1 and FPN1, to explore the correlations between ferrous iron and its specific transporters after ICH. Methods: Ninety-six Sprague-Dawley rats received intra-striatal infusions of 0.5 U type IV collagenase to establish ICH model. Ferrous iron content in brain was determined using Turnbull’s method. DMT1 and FPN1 expression were examined by immunohistochemical staining and Real-Time quantitative polymerase chain reaction (RT-PCR). With the use of confocal laser microscopy, we determined the colocalization of DMT1 and FPN1 at 1, 3, 7 and 14 days after ICH. Results: Ferrous iron deposition was shown in the perihematomal zone as early as 1 day after ICH; it reached a peak after 7 days and was not elevated within 14 days following ICH. The expression of the DMT1 upregulated and reached to peak at day 7 after ICH. FPN1 reached a plateau at 3 days post-ICH. Expression levels of DMT1 and FPN1 were in parallel with ferrous iron deposition. There was a positive correlation between FPN1 and DMT1. DMT1 mainly localized in the cytoplasm of glias and neurons. FPN1 were mostly distributed on the membrane of endothelial cells and glias. Confocal microscope showed that DMT1 colocalized with FPN1. Conclusions: DMT1 and FPN1 are positively influenced by ferrous iron status in brain after ICH. DMT1 and FPN1 attenuate iron overload after ICH via increasing transmembrane iron export. PMID:26617777

  7. Heat transport system

    DOEpatents

    Harkness, S.D.

    A falling bed of ceramic particles receives neutron irradiation from a neutron-producing plasma and thereby transports energy as heat from the plasma to a heat exchange location where the ceramic particles are cooled by a gas flow. The cooled ceramic particles are elevated to a location from which they may again pass by gravity through the region where they are exposed to neutron radiation. Ceramic particles of alumina, magnesia, silica and combinations of these materials are contemplated as high-temperature materials that will accept energy from neutron irradiation. Separate containers of material incorporating lithium are exposed to the neutron flux for the breeding of tritium that may subsequently be used in neutron-producing reactions. The falling bed of ceramic particles includes velocity partitioning between compartments near to the neutron-producing plasma and compartments away from the plasma to moderate the maximum temperature in the bed.

  8. Heat transport system

    DOEpatents

    Harkness, Samuel D.

    1982-01-01

    A falling bed of ceramic particles receives neutron irradiation from a neutron-producing plasma and thereby transports energy as heat from the plasma to a heat exchange location where the ceramic particles are cooled by a gas flow. The cooled ceramic particles are elevated to a location from which they may again pass by gravity through the region where they are exposed to neutron radiation. Ceramic particles of alumina, magnesia, silica and combinations of these materials are contemplated as high-temperature materials that will accept energy from neutron irradiation. Separate containers of material incorporating lithium are exposed to the neutron flux for the breeding of tritium that may subsequently be used in neutron-producing reactions. The falling bed of ceramic particles includes velocity partitioning between compartments near to the neutron-producing plasma and compartments away from the plasma to moderate the maximum temperature in the bed.

  9. Iron-titanium oxyhydroxides which transport water into the deep upper mantle and mantle transition zone

    NASA Astrophysics Data System (ADS)

    Matsukage, K. N.; Nishihara, Y.

    2015-12-01

    We experimentally discovered a new hydrous phase in the system FeOOH-TiO2 at pressures of 10-16 GPa and temperatures of 1000-1600°C which corresponds to conditions of the deep upper mantle and the Earth's mantle transition zone. Seven different compositions in the FeOOH-TiO2 system having molar ratios of x = Ti/(Fe + Ti) = 0, 0.125, 0.25, 0.375, 0.5, 0.75 that were prepared by mixing reagent grade a-FeOOH (goethite) and TiO2 (anatase) powders were used as starting materials. High-pressure and high-temperature experiments were carried out using Kawai-type multi-anvil apparatus (Orange-1000 at Ehime University and SPI-1000 at Tokyo Institute of Technology). In this system, we identified two stable iron-titanium oxyhydroxide phases whose estimated composition is expressed by (FeH)1 - xTixO2 . One is the Fe-rich solid solution (x < 0.23) with e-FeOOH type crystal structure (e-phase, orthorhombic, P21nm) that was described by the previous studies (e.g., Suzuki 2010), and the other is the more Ti-rich solid solution (x > 0.35) with a-PbO2 type structure (a-phase, orthorhombic, Pbcn). The a-phase is stable up to 1500ºC for a composition of x = 0.5 and at least to 1600ºC for x = 0.75. Our result means that this phase is stable at average mantle temperature in the Earth's mantle transition zone. The Iron-titanium-rich hydrous phases was possible to stable in basalt + H2O system (e.g., Hashimoto and Matsukage 2013). Therefore our findings suggest that water transport in the Earth's deep interior is probably much more efficient than had been previously thought.

  10. System and method for producing metallic iron

    SciTech Connect

    Englund, David J.; Schlichting, Mark; Meehan, John; Crouch, Jeremiah; Wilson, Logan

    2014-07-29

    A method of production of metallic iron nodules comprises assembling a hearth furnace having a moveable hearth comprising refractory material and having a conversion zone and a fusion zone, providing a hearth material layer comprising carbonaceous material on the refractory material, providing a layer of reducible material comprising and iron bearing material arranged in discrete portions over at least a portion of the hearth material layer, delivering oxygen gas into the hearth furnace to a ratio of at least 0.8:1 ponds of oxygen to pounds of iron in the reducible material to heat the conversion zone to a temperature sufficient to at least partially reduce the reducible material and to heat the fusion zone to a temperature sufficient to at least partially reduce the reducible material, and heating the reducible material to form one or more metallic iron nodules and slag.

  11. Fur-Regulated Iron Uptake System of Edwardsiella ictaluri and Its Influence on Pathogenesis and Immunogenicity in the Catfish Host

    PubMed Central

    Golden, Greg; Wanda, Soo-Young; Curtiss, Roy

    2012-01-01

    The ability of bacterial pathogens to take up iron from the host during infection is necessary for their multiplication within the host. However, host high-affinity iron binding proteins limit levels of free iron in fluids and tissues. To overcome this deficiency of iron during infection, bacterial pathogens have developed iron uptake systems that are upregulated in the absence of iron, typically tightly controlled by the ferric uptake regulator (Fur) protein. The iron uptake system of Edwardsiella ictaluri, a host-restricted pathogen of channel catfish (Ictalurus punctatus) and the main pathogen of this fish in aquaculture, is unknown. Here we describe the E. ictaluri Fur protein, the iron uptake machinery controlled by Fur, and the effects of fur gene deletion on virulence and immunogenicity in the fish host. Analysis of the E. ictaluri Fur protein shows that it lacks the N-terminal region found in the majority of pathogen-encoded Fur proteins. However, it is fully functional in regulated genes encoding iron uptake proteins. E. ictaluri grown under iron-limited conditions upregulates an outer membrane protein (HemR) that shows heme-hemoglobin transport activity and is tightly regulated by Fur. In vivo studies showed that an E. ictaluri Δfur mutant is attenuated and immune protective in zebrafish (Danio rerio) and catfish (Ictalurus punctatus), triggering systemic immunity. We conclude that an E. ictaluri Δfur mutant could be an effective component of an immersion-oral vaccine for the catfish industry. PMID:22615248

  12. Effects of aspirin on expression of iron transport and storage proteins in BV-2 microglial cells.

    PubMed

    Xu, Yan Xin; Du, Fang; Jiang, Li Rong; Gong, Jing; Zhou, Yu-Fu; Luo, Qian Qian; Qian, Zhong Ming; Ke, Ya

    2015-12-01

    In the light of recent studies, we hypothesized that aspirin might have the functions to regulate the expression of iron transport proteins and then affect cellular iron levels. To test this hypothesis, we investigated the effects of aspirin on expression of iron uptake protein transferrin receptor 1 (TfR1), iron release protein ferroportin 1 (Fpn1) and iron storage protein ferritin using Western blot analysis and on tumor necrosis factor (TNF)-αlpha, interleukin (IL)-6, interleukin (IL)-10 and hepcidin using quantitative real-time PCR in BV-2 microglial cells treated with lipopolysaccharides (LPS). We found that aspirin significantly down-regulated TfR1, while also up-regulated Fpn1 and ferritin expressions in BV-2 microglial cells in vitro. We also showed that TfR1 and Fpn1 expressions were significantly higher, while ferritin contents, IL-6, TNF-alpha and hepcidin mRNA levels were lower in cells treated with aspirin plus LPS than those in cells treated with LPS only. We concluded that aspirin has a negative effect on cell iron contents under 'normal' conditions and could partly reverse LPS-induced-disruption in cell iron balance under in vitro inflammatory conditions. Our findings also suggested that hepcidin might play a dominant role in the control of TfR1 expression by aspirin in the cells treated with LPS. PMID:26522688

  13. Advanced Transport Operating Systems Program

    NASA Technical Reports Server (NTRS)

    White, John J.

    1990-01-01

    NASA-Langley's Advanced Transport Operating Systems Program employs a heavily instrumented, B 737-100 as its Transport Systems Research Vehicle (TRSV). The TRSV has been used during the demonstration trials of the Time Reference Scanning Beam Microwave Landing System (TRSB MLS), the '4D flight-management' concept, ATC data links, and airborne windshear sensors. The credibility obtainable from successful flight test experiments is often a critical factor in the granting of substantial commitments for commercial implementation by the FAA and industry. In the case of the TRSB MLS, flight test demonstrations were decisive to its selection as the standard landing system by the ICAO.

  14. Higher concentrations of nanoscale zero-valent iron (nZVI) in soil induced rice chlorosis due to inhibited active iron transportation.

    PubMed

    Wang, Jie; Fang, Zhanqiang; Cheng, Wen; Yan, Xiaomin; Tsang, Pokeung Eric; Zhao, Dongye

    2016-03-01

    In this study, the effects of concentrations 0, 100, 250, 500, 750 and 1000 mg kg(-1) of nanoscale zero-valent iron (nZVI) on germination, seedlings growth, physiology and toxicity mechanisms were investigated. The results showed that nZVI had no effect on germination, but inhibited the rice seedlings growth in higher concentrations (>500 mg kg(-1) nZVI). The highest suppression rate of the length of roots and shoots reached 46.9% and 57.5%, respectively. The 1000mg kg(-1) nZVI caused the highest suppression rates for chlorophyll and carotenoids, at 91.6% and 85.2%, respectively. In addition, the activity of antioxidant enzymes was altered by the translocation of nanoparticles and changes in active iron content. Visible symptoms of iron deficiency were observed at higher concentrations, at which the active iron content decreased 61.02% in the shoots, but the active iron content not decreased in roots. Interestingly, the total and available amounts of iron in the soil were not less than those in the control. Therefore, the plants iron deficiency was not caused by (i) deficiency of available iron in the soil and (ii) restraint of the absorption that plant takes in the available iron, while induced by (ⅲ) the transport of active iron from the root to the shoot was blocked. The cortex tissues were seriously damaged by nZVI which was transported from soil to the root, these were proved by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS). This current study shows that the mechanism of iron deficiency in rice seedling was due to transport of active iron from the root to the shoot blocked, which was caused by the uptake of nZVI. PMID:26803790

  15. System and method for producing metallic iron nodules

    DOEpatents

    Bleifuss, Rodney L.; Englund, David J.; Iwasaki, Iwao; Lindgren, Andrew J.; Kiesel, Richard F.

    2011-09-20

    A method for producing metallic iron nodules by assembling a shielding entry system to introduce coarse carbonaceous material greater than 6 mesh in to the furnace atmosphere at location(s) where the temperature of the furnace atmosphere adjacent at least partially reduced reducible iron bearing material is between about 2200 and 2650.degree. F. (1200 and 1450.degree. C.), the shielding entry system adapted to inhibit emission of infrared radiation from the furnace atmosphere and seal the furnace atmosphere from exterior atmosphere while introducing coarse carbonaceous material greater than 6 mesh into the furnace to be distributed over the at least partially reduced reducible iron bearing material, and heating the covered at least partially reduced reducible iron bearing material in a fusion atmosphere to assist in fusion and inhibit reoxidation of the reduced material during fusion to assist in fusion and inhibit reoxidation of the reduced material in forming metallic iron nodules.

  16. The Bradyrhizobium japonicum Ferrous Iron Transporter FeoAB Is Required for Ferric Iron Utilization in Free Living Aerobic Cells and for Symbiosis.

    PubMed

    Sankari, Siva; O'Brian, Mark R

    2016-07-22

    The bacterium Bradyrhizobium japonicum USDA110 does not synthesize siderophores for iron utilization in aerobic environments, and the mechanism of iron uptake within symbiotic soybean root nodules is unknown. An mbfA bfr double mutant defective in iron export and storage activities cannot grow aerobically in very high iron medium. Here, we found that this phenotype was suppressed by loss of function mutations in the feoAB operon encoding ferrous (Fe(2+)) iron uptake proteins. Expression of the feoAB operon genes was elevated under iron limitation, but mutants defective in either gene were unable to grow aerobically over a wide external ferric (Fe(3+)) iron (FeCl3) concentration range. Thus, FeoAB accommodates iron acquisition under iron limited and iron replete conditions. Incorporation of radiolabel from either (55)Fe(2+) or (59)Fe(3+) into cells was severely defective in the feoA and feoB strains, suggesting Fe(3+) reduction to Fe(2+) prior to traversal across the cytoplasmic membrane by FeoAB. The feoA or feoB deletion strains elicited small, ineffective nodules on soybean roots, containing few bacteria and lacking nitrogen fixation activity. A feoA(E40K) mutant contained partial iron uptake activity in culture that supported normal growth and established an effective symbiosis. The feoA(E40K) strain had partial iron uptake activity in situ within nodules and in isolated cells, indicating that FeoAB is the iron transporter in symbiosis. We conclude that FeoAB supports iron acquisition under limited conditions of soil and in the iron-rich environment of a symbiotic nodule. PMID:27288412

  17. Tether Transportation System Study

    NASA Technical Reports Server (NTRS)

    Bangham, M. E.; Lorenzini, E.; Vestal, L.

    1998-01-01

    The projected traffic to geostationary earth orbit (GEO) is expected to increase over the next few decades. At the same time, the cost of delivering payloads from the Earth's surface to low earth orbit (LEO) is projected to decrease, thanks in part to the Reusable Launch Vehicle (RLV). A comparable reduction in the cost of delivering payloads from LEO to GEO is sought. The use of in-space tethers, eliminating the requirement for traditional chemical upper stages and thereby reducing the launch mass, has been identified as such an alternative. Spinning tethers are excellent kinetic energy storage devices for providing the large delta vee's required for LEO to GEO transfer. A single-stage system for transferring payloads from LEO to GEO was proposed some years ago. The study results presented here contain the first detailed analyses of this proposal, its extension to a two-stage system, and the likely implementation of the operational system.

  18. Dissolved iron anomaly in the deep tropical-subtropical Pacific: Evidence for long-range transport of hydrothermal iron

    NASA Astrophysics Data System (ADS)

    Wu, Jingfeng; Wells, Mark L.; Rember, Robert

    2011-01-01

    Dissolved iron profiles along a north-south transect along 158°W in the tropical Pacific show evidence of two deepwater anomalies. The first extends from Station ALOHA (22.78°N) to the equator at ˜1000-1500 m and lies below the maximum apparent oxygen utilization and nutrient (N, P) concentrations. The feature is not supported by vertical export processes, but instead corresponds with the lateral dilution field of δ 3He derived from the Loihi seamount, Hawaii, though a sediment source associated with the Hawaiian Island Chain cannot be entirely ruled out. The second, deeper (2000-3000 m) anomaly occurs in tropical South Pacific waters (7°S) and also does not correlate with the depths of maximum nutrient concentrations or apparent oxygen utilization, but it does coincide closely with δ 3He emanating from the East Pacific Rise, more than 5000 km to the east. We hypothesize that these anomalies represent the long-range (>2000 km) transport of hydrothermal iron residuals, stabilized against scavenging by complexation with excess organic ligands in the plume source regions. Such trace leakage of hydrothermal iron to distal plume regions would have been difficult to identify in most hydrothermal vent mapping studies because low analytical detection limits were not needed for the proximal plume regions. These findings suggest that hydrothermal activity may represent a major source of dissolved iron throughout the South Pacific deep basin today, as well as other regions having high mid-ocean spreading rates in the geologic past. In particular, we hypothesize that high spreading rates along the South Atlantic and Southern Ocean mid-oceanic ridges, combined with the upwelling ventilation of these distal hydrothermal plumes, may have increased ocean productivity and carbon export in the Southern Ocean. Assessing the magnitude and persistence of dissolved hydrothermal iron in basin scale deep waters will be important for understanding the marine biogeochemistry of iron

  19. Uptake and Transport of Superparamagnetic Iron Oxide Nanoparticles through Human Brain Capillary Endothelial Cells

    PubMed Central

    2013-01-01

    The blood–brain barrier (BBB) formed by brain capillary endothelial cells (BCECs) constitutes a firm physical, chemical, and immunological barrier, making the brain accessible to only a few percent of potential drugs intended for treatment inside the central nervous system. With the purpose of overcoming the restraints of the BBB by allowing the transport of drugs, siRNA, or DNA into the brain, a novel approach is to use superparamagnetic iron oxide nanoparticles (SPIONs) as drug carriers. The aim of this study was to investigate the ability of fluorescent SPIONs to pass through human brain microvascular endothelial cells facilitated by an external magnet. The ability of SPIONs to penetrate the barrier was shown to be significantly stronger in the presence of an external magnetic force in an in vitro BBB model. Hence, particles added to the luminal side of the in vitro BBB model were found in astrocytes cocultured at a remote distance on the abluminal side, indicating that particles were transported through the barrier and taken up by astrocytes. Addition of the SPIONs to the culture medium did not negatively affect the viability of the endothelial cells. The magnetic force-mediated dragging of SPIONs through BCECs may denote a novel mechanism for the delivery of drugs to the brain. PMID:23919894

  20. Arabidopsis IRT2 cooperates with the high-affinity iron uptake system to maintain iron homeostasis in root epidermal cells.

    PubMed

    Vert, Grégory; Barberon, Marie; Zelazny, Enric; Séguéla, Mathilde; Briat, Jean-François; Curie, Catherine

    2009-05-01

    Iron is an essential nutrient for all organisms but toxic when present in excess. Consequently, plants carefully regulate their iron uptake, dependent on the FRO2 ferric reductase and the IRT1 transporter, to control its homeostasis. Arabidopsis IRT2 gene, whose expression is induced in root epidermis upon iron deprivation, was shown to encode a functional iron/zinc transporter in yeast, and proposed to function in iron acquisition from the soil. In this study, we demonstrate that, unlike its close homolog IRT1, IRT2 is not involved in iron absorption from the soil since overexpression of IRT2 does not rescue the iron uptake defect of irt1-1 mutant and since a null irt2 mutant shows no chlorosis in low iron. Consistently, an IRT2-green fluorescent fusion protein, transiently expressed in culture cells, localizes to intracellular vesicles. However, IRT2 appears strictly co-regulated with FRO2 and IRT1, supporting the view that IRT2 is an integral component of the root response to iron deficiency in root epidermal cells. We propose a model where IRT2 likely prevents toxicity from IRT1-dependent iron fluxes in epidermal cells, through compartmentalization. PMID:19252923

  1. Diagnosis of energy transport in iron buried layer targets using an extreme ultraviolet laser

    SciTech Connect

    Shahzad, M.; Culfa, O.; Rossall, A. K.; Tallents, G. J.; Wilson, L. A.; Guilbaud, O.; Kazamias, S.; Delmas, O.; Demailly, J.; Maitrallain, A.; Pittman, M.; Baynard, E.; Farjardo, M.

    2015-02-15

    We demonstrate the use of extreme ultra-violet (EUV) laboratory lasers in probing energy transport in laser irradiated solid targets. EUV transmission through targets containing a thin layer of iron (50 nm) encased in plastic (CH) after irradiation by a short pulse (35 fs) laser focussed to irradiances 3 × 10{sup 16} Wcm{sup −2} is measured. Heating of the iron layer gives rise to a rapid decrease in EUV opacity and an increase in the transmission of the 13.9 nm laser radiation as the iron ionizes to Fe{sup 5+} and above where the ion ionisation energy is greater than the EUV probe photon energy (89 eV). A one dimensional hydrodynamic fluid code HYADES has been used to simulate the temporal variation in EUV transmission (wavelength 13.9 nm) using IMP opacity values for the iron layer and the simulated transmissions are compared to measured transmission values. When a deliberate pre-pulse is used to preform an expanding plastic plasma, it is found that radiation is important in the heating of the iron layer while for pre-pulse free irradiation, radiation transport is not significant.

  2. The Arabidopsis YELLOW STRIPE LIKE4 and 6 Transporters Control Iron Release from the Chloroplast[C][W

    PubMed Central

    Divol, Fanchon; Couch, Daniel; Conéjéro, Geneviève; Roschzttardtz, Hannetz; Mari, Stéphane; Curie, Catherine

    2013-01-01

    In most plant cell types, the chloroplast represents the largest sink for iron, which is both essential for chloroplast metabolism and prone to cause oxidative damage. Here, we show that to buffer the potentially harmful effects of iron, besides ferritins for storage, the chloroplast is equipped with specific iron transporters that respond to iron toxicity by removing iron from the chloroplast. We describe two transporters of the YELLOW STRIPE1-LIKE family from Arabidopsis thaliana, YSL4 and YSL6, which are likely to fulfill this function. Knocking out both YSL4 and YSL6 greatly reduces the plant’s ability to cope with excess iron. Biochemical and immunolocalization analyses showed that YSL6 resides in the chloroplast envelope. Elemental analysis and histochemical staining indicate that iron is trapped in the chloroplasts of the ysl4 ysl6 double mutants, which also accumulate ferritins. Also, vacuolar iron remobilization and NRAMP3/4 expression are inhibited. Furthermore, ubiquitous expression of YSL4 or YSL6 dramatically reduces plant tolerance to iron deficiency and decreases chloroplastic iron content. These data demonstrate a fundamental role for YSL4 and YSL6 in managing chloroplastic iron. YSL4 and YSL6 expression patterns support their physiological role in detoxifying iron during plastid dedifferentiation occurring in embryogenesis and senescence. PMID:23512854

  3. Transport Systems in Halophilic Fungi.

    PubMed

    Plemenitaš, Ana; Konte, Tilen; Gostinčar, Cene; Cimerman, Nina Gunde

    2016-01-01

    Fungi that tolerate very high environmental NaCl concentrations are good model systems to study mechanisms that enable them to endure osmotic and salinity stress. The whole genome sequences of six such fungal species have been analysed: Hortaea werneckii, Wallemia ichthyophaga and four Aureobasidium spp.: A. pullulans, A. subglaciale, A. melanogenum and A. namibiae. These fungi show different levels of halotolerance, with the presence of numerous membrane transport systems uncovered here that are believed to maintain physiological intracellular concentrations of alkali metal cations. Despite some differences, the intracellular cation contents of H. werneckii, A. pullulans and W. ichthyophaga remain low even under extreme extracellular salinities, which suggests that these species have efficient cation transport systems. We speculate that cation transporters prevent intracellular accumulation of Na(+), and thus avoid the toxic effects that such Na(+) accumulation would have, while also maintaining the high K(+)/Na(+) ratio that is required for the full functioning of the cell - another crucial task in high-Na(+) environments. This chapter primarily summarises the cation transport systems of these selected fungi, and it also describes other membrane transporters that might be involved in their mechanisms of halotolerance. PMID:26721280

  4. Earthquake damage to transportation systems

    USGS Publications Warehouse

    McCullough, Heather

    1994-01-01

    Earthquakes represent one of the most destructive natural hazards known to man. A large magnitude earthquake near a populated area can affect residents over thousands of square kilometers and cause billions of dollars in property damage. Such an event can kill or injure thousands of residents and disrupt the socioeconomic environment for months, sometimes years. A serious result of a large-magnitude earthquake is the disruption of transportation systems, which limits post-disaster emergency response. Movement of emergency vehicles, such as police cars, fire trucks and ambulances, is often severely restricted. Damage to transportation systems is categorized below by cause including: ground failure, faulting, vibration damage, and tsunamis.

  5. Electron transport in the dissimilatory iron reducer, GS-15

    USGS Publications Warehouse

    Gorby, Y.A.; Lovley, D.R.

    1991-01-01

    Mechanisms for electron transport to Fe(III) were investigated in GS-15, anovel anaerobic microorganism which can obtain energy for growth hy coupling the complete oxidation of organic acids or aromatic compounds to the reduction of Fe(III) to Fe(II). The results indicate that Fe(III) reduction proceeds through a type b cytochrome and a membrane-bound Fe(III) reductase which is distinct from the nitrate reductase.

  6. Preliminary Hazards Assessment: Iron disulfide purification system

    SciTech Connect

    1991-07-30

    A process for the purification (washing) of iron disulfide (FeS{sub 2}) powder is conducted in the Northeast corner (Area 353) of the main plant building (Building 100). This location is about 130 feet from the fenced boundary of the Partnership School/Child Development Center. In the first steps of the process, raw iron disulfide powder is ground and separated by particle size. The ground and sized powder is then purified in a three-step acid washing process using both hydrochloric acid (HCI) and hydrofluoric (HF) acid. The iron disulfide process is an intermittent batch process conducted four to eight times a year. This study is a Preliminary Hazards Assessment (PHA) to assess the hazards associated with the iron disulfide process. This is a preliminary study and will be used to determine if additional safety analysis is necessary. The scope of the PHA includes assessment of the process steps of grinding, size classification, and purification. The purpose is to identify major hazards and determine if the current and newly added safeguards are adequate for operation. The PHA also lists recommendations for additional safety features that should be added to reduce the risks of operation.

  7. Surveillance systems for intermodal transportation

    NASA Astrophysics Data System (ADS)

    Jakovlev, Sergej; Voznak, Miroslav; Andziulis, Arunas

    2015-05-01

    Intermodal container monitoring is considered a major security issue in many major logistic companies and countries worldwide. Current representation of the problem, we face today, originated in 2002, right after the 9/11 attacks. Then, a new worldwide Container Security Initiative (CSI, 2002) was considered that shaped the perception of the transportation operations. Now more than 80 larger ports all over the world contribute to its further development and integration into everyday transportation operations and improve the regulations for the developing regions. Although, these new improvements allow us to feel safer and secure, constant management of transportation operations has become a very difficult problem for conventional data analysis methods and information systems. The paper deals with a proposal of a whole new concept for the improvement of the Containers Security Initiative (CSI) by virtually connecting safety, security processes and systems. A conceptual middleware approach with deployable intelligent agent modules is proposed to be used with possible scenarios and a testbed is used to test the solution. Middleware examples are visually programmed using National Instruments LabView software packages and Wireless sensor network hardware modules. An experimental software is used to evaluate he solution. This research is a contribution to the intermodal transportation and is intended to be used as a means or the development of intelligent transport systems.

  8. Determination of thermooptical and transport parameters of ε iron(III) oxide-based nanocomposites by beam deflection spectroscopy

    NASA Astrophysics Data System (ADS)

    Korte, Dorota; Carraro, Giorgio; Maccato, Chiara; Franko, Mladen

    2015-04-01

    In this work, photothermal beam deflection (PBD) experiments have been used to characterize the thermooptical and transport properties of ε-Fe2O3-based nanocomposites. In particular, iron(III) nanostructures have been functionalized with Au, Ag and Cu nanoparticles, tailoring both their nano-organization and their chemical state. In order to elucidate the correlation between the thermooptical and transport parameters, the structural, compositional and morphological properties of Fe2O3-based systems were studied by field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). It was observed that the optothermal and transport parameters were influenced by the nature and oxidation state of the nanoparticles, which can serve as a key tool to master the material properties for their application in light-assisted processes.

  9. Dual Regulation of the Arabidopsis High-Affinity Root Iron Uptake System by Local and Long-Distance Signals1

    PubMed Central

    Vert, Grégory A.; Briat, Jean-François; Curie, Catherine

    2003-01-01

    Regulation of the root high-affinity iron uptake system by whole-plant signals was investigated at the molecular level in Arabidopsis, through monitoring FRO2 and IRT1 gene expression. These two genes encode the root ferric-chelate reductase and the high-affinity iron transporter, respectively, involved in the iron deficiency-induced uptake system. Recovery from iron-deficient conditions and modulation of apoplastic iron pools indicate that iron itself plays a major role in the regulation of root iron deficiency responses at the mRNA and protein levels. Split-root experiments show that the expression of IRT1 and FRO2 is controlled both by a local induction from the root iron pool and through a systemic pathway involving a shoot-borne signal, both signals being integrated to tightly control production of the root iron uptake proteins. We also show that IRT1 and FRO2 are expressed during the day and down-regulated at night and that this additional control is overruled by iron starvation, indicating that the nutritional status prevails on the diurnal regulation. Our work suggests, for the first time to our knowledge, that like in grasses, the root iron acquisition in strategy I plants may also be under diurnal regulation. On the basis of the new molecular insights provided in this study and given the strict coregulation of IRT1 and FRO2 observed, we present a model of local and long-distance regulation of the root iron uptake system in Arabidopsis. PMID:12805609

  10. Dual regulation of the Arabidopsis high-affinity root iron uptake system by local and long-distance signals.

    PubMed

    Vert, Grégory A; Briat, Jean-François; Curie, Catherine

    2003-06-01

    Regulation of the root high-affinity iron uptake system by whole-plant signals was investigated at the molecular level in Arabidopsis, through monitoring FRO2 and IRT1 gene expression. These two genes encode the root ferric-chelate reductase and the high-affinity iron transporter, respectively, involved in the iron deficiency-induced uptake system. Recovery from iron-deficient conditions and modulation of apoplastic iron pools indicate that iron itself plays a major role in the regulation of root iron deficiency responses at the mRNA and protein levels. Split-root experiments show that the expression of IRT1 and FRO2 is controlled both by a local induction from the root iron pool and through a systemic pathway involving a shoot-borne signal, both signals being integrated to tightly control production of the root iron uptake proteins. We also show that IRT1 and FRO2 are expressed during the day and down-regulated at night and that this additional control is overruled by iron starvation, indicating that the nutritional status prevails on the diurnal regulation. Our work suggests, for the first time to our knowledge, that like in grasses, the root iron acquisition in strategy I plants may also be under diurnal regulation. On the basis of the new molecular insights provided in this study and given the strict coregulation of IRT1 and FRO2 observed, we present a model of local and long-distance regulation of the root iron uptake system in Arabidopsis. PMID:12805609

  11. Novel two-component transmembrane transcription control: regulation of iron dicitrate transport in Escherichia coli K-12.

    PubMed Central

    Van Hove, B; Staudenmaier, H; Braun, V

    1990-01-01

    Citrate and iron have to enter only the periplasmic space in order to induce the citrate-dependent iron(III) transport system of Escherichia coli. The five transport genes fecABCDE form an operon and are transcribed from fecA to fecE. Two genes, termed fecI and fecR, that mediate induction by iron(III) dicitrate have been identified upstream of fecA. The fecI gene encodes a protein of 173 amino acids (molecular weight, 19,478); the fecR gene encodes a protein of 317 amino acids (molecular weight, 35,529). Chromosomal fecI::Mu d1 mutants were unable to grow with iron(III) dicitrate as the sole iron source and synthesized no FecA outer membrane receptor protein. Growth was restored by transformation with plasmids encoding fecI or fecI and fecR. FecA and beta-galactosidase syntheses under transcription control of the fecB gene (fecB::Mu d1) were constitutive in fecI transformants and were regulated by iron(III) dicitrate in fecI fecR transformants. The amino acid sequence of the FecI protein contains a region close to the carboxy-terminal end for which a helix-turn-helix motif is predicted, which is typical for DNA-binding regulatory proteins. The FecI protein was found in the membrane, and the FecR protein was found in the periplasmic fraction. It is proposed that the FecR protein is the sensor that recognizes iron(III) dicitrate in the periplasm. The FecI protein activates fec gene expression by binding to the fec operator region. In the absence of citrate, FecR inactivates FecI. The lack of sequence homologies to other transmembrane signaling proteins and the location of the two proteins suggest a new type of transmembrane control mechanism. Images PMID:2254251

  12. Novel two-component transmembrane transcription control: regulation of iron dicitrate transport in Escherichia coli K-12.

    PubMed

    Van Hove, B; Staudenmaier, H; Braun, V

    1990-12-01

    Citrate and iron have to enter only the periplasmic space in order to induce the citrate-dependent iron(III) transport system of Escherichia coli. The five transport genes fecABCDE form an operon and are transcribed from fecA to fecE. Two genes, termed fecI and fecR, that mediate induction by iron(III) dicitrate have been identified upstream of fecA. The fecI gene encodes a protein of 173 amino acids (molecular weight, 19,478); the fecR gene encodes a protein of 317 amino acids (molecular weight, 35,529). Chromosomal fecI::Mu d1 mutants were unable to grow with iron(III) dicitrate as the sole iron source and synthesized no FecA outer membrane receptor protein. Growth was restored by transformation with plasmids encoding fecI or fecI and fecR. FecA and beta-galactosidase syntheses under transcription control of the fecB gene (fecB::Mu d1) were constitutive in fecI transformants and were regulated by iron(III) dicitrate in fecI fecR transformants. The amino acid sequence of the FecI protein contains a region close to the carboxy-terminal end for which a helix-turn-helix motif is predicted, which is typical for DNA-binding regulatory proteins. The FecI protein was found in the membrane, and the FecR protein was found in the periplasmic fraction. It is proposed that the FecR protein is the sensor that recognizes iron(III) dicitrate in the periplasm. The FecI protein activates fec gene expression by binding to the fec operator region. In the absence of citrate, FecR inactivates FecI. The lack of sequence homologies to other transmembrane signaling proteins and the location of the two proteins suggest a new type of transmembrane control mechanism. PMID:2254251

  13. Effect of dietary iron deficiency and overload on the expression of ZIP metal-ion transporters in rat liver

    PubMed Central

    Nam, Hyeyoung; Knutson, Mitchell D.

    2015-01-01

    The mammalian ZIP (Zrt-, Irt-like Protein) family of transmembrane transport proteins consists of 14 members that share considerable homology. ZIP proteins have been shown to mediate the cellular uptake of the essential trace elements zinc, iron, and manganese. The aim of the present study was to determine the effect of dietary iron deficiency and overload on the expression of all 14 ZIP transporters in the liver, the main site of iron storage. Weanling male rats (n=6/group) were fed iron-deficient (FeD), iron-adequate (FeA), or iron-overloaded (FeO) diets in two independent feeding studies. In study 1, diets were based on the TestDiet 5755 formulation and contained iron at 9 ppm (FeD), 215 ppm (FeA), and 27,974 ppm (3% FeO). In study 2, diets were based on the AIN-93G formulation and contained iron at 9 ppm Fe (FeD), 50 ppm Fe (FeA), or 18916 ppm (2% FeO). After 3 weeks, the FeD diets depleted liver non-heme iron stores and induced anemia, whereas FeO diets resulted in hepatic iron overload. Quantitative RT-PCR revealed that ZIP5 mRNA levels were 3- and 8-fold higher in 2% FeO and 3% FeO livers, respectively, compared with FeA controls. In both studies, a consistent downregulation of ZIP6, ZIP7, and ZIP10 was also observed in FeO liver relative to FeA controls. Studies in H4IIE hepatoma cells further documented that iron loading affects the expression of these ZIP transporters. Overall, our data suggest that ZIP5, ZIP6, ZIP7, and ZIP10 are regulated by iron, indicating that they may play a role in hepatic iron/metal homeostasis during iron deficiency and overload. PMID:21826460

  14. Optimal concentrations in transport systems

    PubMed Central

    Jensen, Kaare H.; Kim, Wonjung; Holbrook, N. Michele; Bush, John W. M.

    2013-01-01

    Many biological and man-made systems rely on transport systems for the distribution of material, for example matter and energy. Material transfer in these systems is determined by the flow rate and the concentration of material. While the most concentrated solutions offer the greatest potential in terms of material transfer, impedance typically increases with concentration, thus making them the most difficult to transport. We develop a general framework for describing systems for which impedance increases with concentration, and consider material flow in four different natural systems: blood flow in vertebrates, sugar transport in vascular plants and two modes of nectar drinking in birds and insects. The model provides a simple method for determining the optimum concentration copt in these systems. The model further suggests that the impedance at the optimum concentration μopt may be expressed in terms of the impedance of the pure (c = 0) carrier medium μ0 as μopt∼2αμ0, where the power α is prescribed by the specific flow constraints, for example constant pressure for blood flow (α = 1) or constant work rate for certain nectar-drinking insects (α = 6). Comparing the model predictions with experimental data from more than 100 animal and plant species, we find that the simple model rationalizes the observed concentrations and impedances. The model provides a universal framework for studying flows impeded by concentration, and yields insight into optimization in engineered systems, such as traffic flow. PMID:23594815

  15. Linking carbon and iron cycles by investigating transport, fate and mineralogy of iron-bearing colloids from peat-draining rivers - Scotland as model for high-latitude rivers

    NASA Astrophysics Data System (ADS)

    Wood, Deborah; Crocket, Kirsty; Brand, Tim; Stutter, Marc; Wilson, Clare; Schröder, Christian

    2016-04-01

    Linking carbon and iron cycles by investigating transport, fate and mineralogy of iron-bearing colloids from peat-draining rivers - Scotland as model for high-latitude rivers Wood, D.A¹, Crocket, K², Brand, T², Stutter, M³, Wilson, C¹ & Schröder, C¹ ¹Biological and Environmental Sciences, University of Stirling, Stirling, FK9 4LA ²Scottish Association for Marine Science, University of the Highlands and Islands, Dunbeg, Oban, PA37 1QA ³James Hutton Institute, Craigiebuckler, Aberdeen, AB15 8QH The biogeochemical iron cycle exerts significant control on the carbon cycle¹. Iron is a limiting nutrient in large areas of the world's oceans and its bioavailability controls CO2 uptake by marine photosynthesizing microorganisms. While atmospheric iron inputs to the open ocean have been extensively measured, global river inputs have likely been underestimated because most major world rivers exhibit extensive iron removal by flocculation and sedimentation during seawater mixing. Iron minerals and organic matter mutually stabilise each other², which results in a 'rusty carbon sink' in sediments³ on the one hand but may also enhance transport beyond the salinity gradient on the other. Humic-rich, high latitude rivers have a higher iron-carrying capacity⁴‑⁶ but are underrepresented in iron flux calculations. The West Coast sea lochs in Scotland are fed by predominantly peatland drainage catchments, and the rivers entering the sea lochs carry a high load of organic matter. The short distance between many of these catchments and the coastal ocean facilitates source-to-sea research investigating transport, fate and mineralogy of iron-bearing colloids providing a good analogue for similar high latitude fjordic systems. We use SeaFAST+ICP-MS and Mössbauer spectroscopy to survey trace metal concentrations, with emphasis on iron concentrations, speciation and mineralogy, across salinity gradients. In combination with ultra-filtration techniques, this allows

  16. Transportation Cluster Volume 7 [Transportation Systems].

    ERIC Educational Resources Information Center

    Pennsylvania State Dept. of Justice, Harrisburg. Bureau of Correction.

    The document is one of seven volumes of instructional materials developed around a cluster of Transportation Industries. Primarily technical in focus, they are designed to be used in a cluster-concept program and to integrate with a regular General Education Development (G.E.D.) program so that students may attain an employable skill level and a…

  17. Influence of cytokines on Dmt1 iron transporter and ferritin expression in insulin-secreting cells.

    PubMed

    Lortz, S; Schröter, S; Stückemann, V; Mehmeti, I; Lenzen, S

    2014-06-01

    Free intracellular ferrous iron (Fe(2+)) is essential for the generation of the extremely toxic hydroxyl radicals, which contribute to β-cell destruction by cytokines. Therefore the expression of the different divalent metal transporter 1 (Dmt1) isoforms and ferritin (Ft) subunits, responsible for iron import and chelation, was analyzed under pro-inflammatory conditions (IL1β alone or together with TNFα+IFNγ). The Dmt1 isoforms (1A/1B and +IRE/-IRE) and the total Dmt1 expression in insulin-producing cells (RINm5F and INS-1E), in primary rat islets and, for comparison, in the neuroendocrine PC12 cell line were quantified by qRT-PCR. In addition, the expression of the light (L-Ft) and heavy Ft (H-Ft) subunits and the mitochondrial Ft isoform (Mtft) in insulin-producing cells under control conditions and after cytokine treatment was estimated. The 1B isoform was the predominant Dmt1 mRNA in all insulin-producing cells, accounting for almost 100% of the 1A/1B isoform expression. For the IRE variants, +IRE expression was higher than -IRE expression. Pro-inflammatory cytokines accelerated the expression of Dmt1 isoforms significantly with an overall 2.5- to 3-fold increase in the total Dmt1 expression. In contrast, the expression of the iron-buffering ferritin subunits L- and H-Ft was unaffected by IL1β and only slightly induced by the cytokine mixture. Mtft expression was also not increased. Dmt1 expression was significantly elevated through pro-inflammatory cytokines, whereas Ft expression was marginally increased. This imbalance between the increased iron transport capacity and the almost unaffected iron storage capacity can foster cytokine-mediated formation of hydroxyl radicals and thus pro-inflammatory cytokine toxicity through elevated free iron concentrations. PMID:24850829

  18. Lunar articulated remote transportation system

    NASA Technical Reports Server (NTRS)

    Beech, Geoffrey; Conley, Gerald; Diaz, Claudine; Dimella, Timothy; Dodson, Pete; Hykin, Jeff; Richards, Byron; Richardson, Kroy; Shetzer, Christie; Vandyke, Melissa

    1990-01-01

    A first generation lunar transportation vehicle was designed for use on the surface of the Moon between the years 2010 and 2020. Attention is focussed on specific design details on all components of the Lunar Articulated Remote Transportation System (Lunar ARTS). The Lunar ARTS will be a three cart, six-wheeled articulated vehicle. It's purpose will be for the transportation of astronauts and/or materials for excavation purposes at a short distance from the base (37.5 kilometers). The power system includes fuel cells for both the primary system and the back-up system. The vehicle has the option of being operated in a manned or unmanned mode. The unmanned mode includes stereo imaging with signal processing for navigation. For manned missions the display console is a digital readout displayed on the inside of the asronaut's helmet. A microprocessor is also on board the vehicle. Other components of the vehicle include: a double wishbone/flexible hemispherical wheel suspension; chassis; a steering system; motors; seat restraints, heat rejection systems; solar flare protection; dust protection; and meteoroid protection. A one-quarter scale dynamic model was built to study the dynamic behavior of the vehicle. The dynamic model closely captures the mechanical and electrical details of the total design.

  19. Lunar articulated remote transportation system

    NASA Technical Reports Server (NTRS)

    1990-01-01

    The students of the Florida A&M/Florida State University College of Engineering continued their design from 1988 to 1989 on a first generation lunar transportation vehicle for use on the surface of the Moon between the years 2010 and 2020. Attention is focused on specific design details on all components of the Lunar Articulated Remote Transportation System (Lunar ARTS). The Lunar ARTS will be a three-cart, six-wheeled articulated vehicle. Its purpose will be the transportation of astronauts and/or materials for excavation purposes at a short distance from the base (37.5 km). The power system includes fuel cells for both the primary system and the back-up system. The vehicle has the option of being operated in a manned or unmanned mode. The unmanned mode includes stereo imaging with signal processing for navigation. For manned missions the display console is a digital readout displayed on the inside of the astronaut's helmet. A microprocessor is also on board the vehicle. Other components of the vehicle include a double wishbone/flexible hemispherical wheel suspension; chassis; a steering system; motors; seat retraints; heat rejection systems; solar flare protection; dust protection; and meteoroid protection. A one-quarter scale dynamic model has been built to study the dynamic behavior of the vehicle. The dynamic model closely captures the mechanical and electrical details of the total design.

  20. Staphylococcus aureus transporters Hts, Sir, and Sst capture iron liberated from human transferrin by Staphyloferrin A, Staphyloferrin B, and catecholamine stress hormones, respectively, and contribute to virulence.

    PubMed

    Beasley, Federico C; Marolda, Cristina L; Cheung, Johnson; Buac, Suzana; Heinrichs, David E

    2011-06-01

    Staphylococcus aureus is a frequent cause of bloodstream, respiratory tract, and skin and soft tissue infections. In the bloodstream, the iron-binding glycoprotein transferrin circulates to provide iron to cells throughout the body, but its iron-binding properties make it an important component of innate immunity. It is well established that siderophores, with their high affinity for iron, in many instances can remove iron from transferrin as a means to promote proliferation of bacterial pathogens. It is also established that catecholamine hormones can interfere with the iron-binding properties of transferrin, thus allowing infectious bacteria access to this iron pool. The present study demonstrates that S. aureus can use either of two carboxylate-type siderophores, staphyloferrin A and staphyloferrin B, via the transporters Hts and Sir, respectively, to access the transferrin iron pool. Growth of staphyloferrin-producing S. aureus in serum or in the presence of holotransferrin was not enhanced in the presence of catecholamines. However, catecholamines significantly enhanced the growth of staphyloferrin-deficient S. aureus in human serum or in the presence of human holotransferrin. It was further demonstrated that the Sst transporter was essential for this activity as well as for the utilization of bacterial catechol siderophores. The substrate binding protein SstD was shown to interact with ferrated catecholamines and catechol siderophores, with low to submicromolar affinities. Experiments involving mice challenged intravenously with wild-type S. aureus and isogenic mutants demonstrated that the combination of Hts, Sir, and Sst transport systems was required for full virulence of S. aureus. PMID:21402762

  1. Integrated Intermodal Passenger Transportation System

    NASA Technical Reports Server (NTRS)

    Klock, Ryan; Owens, David; Schwartz, Henry; Plencner, Robert

    2012-01-01

    Modern transportation consists of many unique modes of travel. Each of these modes and their respective industries has evolved independently over time, forming a largely incoherent and inefficient overall transportation system. Travelers today are forced to spend unnecessary time and efforts planning a trip through varying modes of travel each with their own scheduling, pricing, and services; causing many travelers to simply rely on their relatively inefficient and expensive personal automobile. This paper presents a demonstration program system to not only collect and format many different sources of trip planning information, but also combine these independent modes of travel in order to form optimal routes and itineraries of travel. The results of this system show a mean decrease in inter-city travel time of 10 percent and a 25 percent reduction in carbon dioxide emissions over personal automobiles. Additionally, a 55 percent reduction in carbon dioxide emissions is observed for intra-city travel. A conclusion is that current resources are available, if somewhat hidden, to drastically improve point to point transportation in terms of time spent traveling, the cost of travel, and the ecological impact of a trip. Finally, future concepts are considered which could dramatically improve the interoperability and efficiency of the transportation infrastructure.

  2. Docosahexaenoic acid enhances iron uptake by modulating iron transporters and accelerates apoptotic death in PC12 cells.

    PubMed

    Schonfeld, Eldi; Yasharel, Ilanit; Yavin, Ephraim; Brand, Annette

    2007-10-01

    The effect of docosahexaenoic acid (DHA; 22:6 n-3) on Fe(2+)-mediated and/or H(2)O(2)-mediated oxidative stress (OS) was investigated in a PC12 pheochromocytoma cell line in the presence or absence of 50 ng/ml nerve growth factor (NGF). DHA-supplemented cells showed enhanced Fe(2+)-induced cell damage as evident by increased lipid peroxides formation (10-fold) and reduced neutral red (NR) dye uptake in a NGF-independent fashion. DHA caused a nearly 10-fold increase in free iron uptake in NGF-treated cells and doubled iron uptake in nondifferentiated cells. DHA-enrichment induced an elevation in the transferrin receptor protein in the nondifferentiated cells whereas NGF-treatment led to a substantial increase in the ubiquitous divalent metal ion transporter 1 (DMT-1) as detected by mRNA levels using qRT-PCR. The mechanism of action of DHA to accelerate cell death may be associated with the externalization of amino-phosphoglycerides (PG) species of which, increased ethanolamine plasmalogen levels, may be essential for cell rescue as noted in NGF-treated PC12 cells. PMID:17551831

  3. THE EFFECT OF WATER CHEMISTRY ON THE PROPERTIES OF IRON PARTICLES AND IRON SUSPENSIONS

    EPA Science Inventory

    The structure and properties of iron colloids in aquatic systems is important in understanding their behavior in environmental and engineering systems. For example the adsorption of contaminants onto iron colloids and subsequent transport through ground water aquifers and surface...

  4. ELS1, a novel MATE transporter related to leaf senescence and iron homeostasis in Arabidopsis thaliana.

    PubMed

    Wang, Zhenyu; Qian, Chongzhen; Guo, Xiaochun; Liu, Erlong; Mao, Kaili; Mu, Changjun; Chen, Ni; Zhang, Wei; Liu, Heng

    2016-08-01

    The multidrug and toxic compound extrusion (MATE) transporters mediate the coupled exchange of organic substrates and monovalent cations have been recently implicated in various plant biological activities. In this work, we isolated a dominant mutant from an Arabidopsis activation-tagging mutant pool. This mutant exhibits pleiotropic phenotype including early flowering, dwarf and bushy architecture, minified lateral organs and early leaf senescence, and is therefore designated early leaf senescence 1-Dominaint (els1-D). Genotyping assays showed that els1-D is a gain-of-function mutant of a novel MATE transporter gene, ELS1, which encodes a close homolog of the previously reported ADP1, BCD1 and DTX50. Further investigations revealed that the overexpression of ELS1 reduces iron content in els1-D, and the accelerated senescence of the detached els1-D leaves can be recovered by exogenous iron supply. In addition, we also found that ELS1 is an iron responsive gene. Based on these findings, we proposed that ELS1 is related to leaf senescence and iron homeostasis in Arabidopsis. PMID:27233612

  5. Iron

    MedlinePlus

    ... organ failure, coma, convulsions, and death. Child-proof packaging and warning labels on iron supplements have greatly ... levodopa that the body absorbs, making it less effective. Levodopa, found in Sinemet® and Stalevo®, is used ...

  6. Method and system for producing metallic iron nuggets

    DOEpatents

    Iwasaki, Iwao; Kiesel, Richard F.; Englund, David J; Hendrickson, Dave

    2012-12-18

    A method and system for producing metallic iron nuggets may include providing multiple layers of agglomerates, such as briquettes, balls and extrusions, of a reducible mixture of reducing material (such as carbonaceous material) and of a reducible iron bearing material (such as iron oxide) on a hearth material layer (such as carbonaceous material) and providing a coarse overlayer of carbonaceous material over at least some of the agglomerates. Heating the agglomerates of reducible mixture to 1425.degree. C. or 1400.degree. C. or 1375.degree. C. results in formation of an intermediate product of one or more metallic iron nuggets, which may have a sulfur content of less than 0.03%, and slag, which may have less than 5% mass MgO, which may have a ratio of percent by weight sulfur in the slag over percent by weight sulfur in the metallic nuggets of at least about 12 or at least about 15.

  7. System and method for making metallic iron with reduced CO.sub.2 emissions

    DOEpatents

    Kiesel, Richard F; Englund, David J; Schlichting, Mark; Meehan, John; Crouch, Jeremiah; Wilson, Logan

    2014-10-14

    A method and system for making metallic iron nodules with reduced CO.sub.2 emissions is disclosed. The method includes: assembling a linear hearth furnace having entry and exit portions, at least a conversion zone and a fusion zone, and a moving hearth adapted to move reducible iron bearing material through the furnace on contiguous hearth sections; assembling a shrouded return substantially free of air ingress extending adjacent at least the conversion and fusion zones of the furnace through which hearth sections can move from adjacent the exit portion to adjacent the entry portion of the furnace; transferring the hearth sections from the furnace to the shrouded return adjacent the exit portion; reducing reducible material in the linear hearth furnace to metallic iron nodules; and transporting gases from at least the fusion zone to the shrouded return to heat the hearth sections while in the shrouded return.

  8. DIVALENT METAL TRANSPORTER-1 REGULATION BY IRON AND VANADIUM MODULATES HYDROGEN PEROXIDE-INDUCED DNA DAMAGE IN LUNG CELLS

    EPA Science Inventory

    The divalent metal transporter-1 (DMT1) participates in the detoxification of metals that can damage lung epithelium. Elevated iron levels increase the expression of DMT1 in bronchial epithelial cells stimulating its uptake and storage in ferritin, thus making iron unavailable t...

  9. Quantitative analysis of dietary iron utilization for erythropoiesis in response to body iron status.

    PubMed

    Matsuo-Tezuka, Yukari; Noguchi-Sasaki, Mariko; Kurasawa, Mitsue; Yorozu, Keigo; Shimonaka, Yasushi

    2016-06-01

    Erythropoiesis requires large amounts of iron for hemoglobin synthesis. There are two sources of iron for erythropoiesis, dietary and stored iron; however, their relative contributions to erythropoiesis remain unknown. In this study, we used the stable iron isotope (57)Fe to quantify synthesis of hemoglobin derived from dietary iron. Using this method, we investigated the activities of dietary iron absorption and the utilization of dietary iron for erythropoiesis in responses to stimulated erythropoiesis and to interventions to alter body iron status. Under iron-loaded conditions, the activity of dietary iron absorption was clearly lowered in response to up-regulation of hepcidin, although the estimated activity of iron release from stored iron was not compared with that under control conditions. This result was supported by the observation that two duodenal iron transporters, divalent metal transporter 1 (DMT1) and ferroportin, were downregulated by iron loading, although the levels of expression of ferroportin in iron storage tissues were not changed by iron loading under erythropoietic stimulation by epoetin-β pegol (C.E.R.A., a long-acting erythropoiesis-stimulating agent). These results indicate that the dietary iron absorption system is more sensitive to body iron status than are reticuloendothelial iron- release mechanisms. Our data indicated that there could be a regulatory mechanism favoring use of stored iron over dietary iron under iron-loaded conditions. PMID:26911670

  10. Thermoelectric Transport Properties of Gold-Iron at Millikelvin Temperatures.

    NASA Astrophysics Data System (ADS)

    Chesire, Daniel Patrick

    Measurements of the electrical resistivity, and both static and isoelectric thermopower have been made on a fine Au wire containing 1 ppm Fe over a range of temperatures between 7 K and 24 mK. A shallow minimum at higher temperatures and unitary limit in the resistivity data characteristic of the Kondo effect were observed in the lower temperature ranges. The minimum coincides with that observed by other workers. Both the resistivity and the two thermopowers were measured with a Superconducting Quantum Interference Detector (SQUID) which has extremely high sensitivity and a very good signal-to-noise ratio. The static and isoelectric thermopowers were measured under two different boundary conditions. The static thermopower was measured by keeping the electric current through the sample equal to zero by using a compensating current source. The isoelectric thermopower was measured under the condition that the electric field across the sample was kept equal to zero by using a superconducting short. The static and isoelectric thermopowers both exhibited a broad minimum attributed to the interaction of a dilute concentration of Fe impurities with the Au conduction electrons. The data have been analyzed in terms of linear transport theory, using the Mueller-Hartmann expression for the Kondo contribution. Since the measurements were made at low temperatures, the diffusion and phonon drag thermopowers were small enough that the major contribution to the measured thermopower was from the Kondo effect. The theory was shown to fit the data well down to 0.2 K. Below this temperature, the theoretical expression for the thermopower did not agree well with the measurements in this work. The static thermopower, S, was found to be related to the isoelectric thermopower, (SIGMA)(,E=0), and the resistivity, (rho), by the simple relation S = (rho)(SIGMA)(,E=0). The isoelectric data was found to have a better signal-to-noise ratio than the static thermopower and a large enough signal at

  11. 9. GENERAL VIEW OF THE CAST IRON TRUSS SYSTEM IN ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    9. GENERAL VIEW OF THE CAST IRON TRUSS SYSTEM IN THE ATTIC OF UNIT 2, SHOWING THE JUNCTION OF THE TRUSSES ABOVE THE MAIN ENTRY GABLE WITH THE TYPICAL TRUSS SYSTEM FOR THE WING; LOOKING SSW. (Ryan and Ceronie) - Watervliet Arsenal, Building No. 40, Broadway between Dalliba & Watervliet Avenues, Watervliet, Albany County, NY

  12. SORTING NEXIN1 is required for modulating the trafficking and stability of the Arabidopsis IRON-REGULATED TRANSPORTER1.

    PubMed

    Ivanov, Rumen; Brumbarova, Tzvetina; Blum, Ailisa; Jantke, Anna-Maria; Fink-Straube, Claudia; Bauer, Petra

    2014-03-01

    Dicotyledonous plants growing under limited iron availability initiate a response resulting in the solubilization, reduction, and uptake of soil iron. The protein factors responsible for these steps are transmembrane proteins, suggesting that the intracellular trafficking machinery may be involved in iron acquisition. In search for components involved in the regulation of Arabidopsis thaliana iron deficiency responses, we identified the members of the SORTING NEXIN (SNX) protein family. SNX loss-of-function plants display enhanced susceptibility to iron deficiency in comparison to the wild type. The absence of SNX led to reduced iron import efficiency into the root. SNX1 showed partial colocalization with the principal root iron importer IRON-REGULATED TRANSPORTER1 (IRT1). In SNX loss-of-function plants, IRT1 protein levels were decreased compared with the wild type due to enhanced IRT1 degradation. This resulted in diminished amounts of the IRT1 protein at the plasma membrane. snx mutants exhibited enhanced iron deficiency responses compared with the wild type, presumably due to the lower iron uptake through IRT1. Our results reveal a role of SNX1 for the correct trafficking of IRT1 and, thus, for modulating the activity of the iron uptake machinery. PMID:24596241

  13. Transportable Collective Protection System (TCPS)

    SciTech Connect

    Tekesky, R.

    1990-08-15

    Human System Division (HSD/YAGD), Wright-Patterson AFB OH 45433-6503 requested assistance from the Air Force Packaging Evaluation Activity (AFPEA) to conduct vibration, shock and environmental testing on three Rowley containers with contents. The contents consist of a Transportable Collective Protective System (TCPS). The TCPS, manufactured by IIC/Dover Inc., is a chemical warfare tent. Personnel can enter the tent, remove protective clothing and perform duties in an uncontaminated environment. The purpose of this project was to determine if the Rowley containers would be able to contain and protect the TCPS during world-wide shipment, storage, and handling.

  14. System and method for producing metallic iron

    SciTech Connect

    Bleifuss, Rodney L.; Englund, David J.; Iwasaki, Iwao; Fosnacht, Donald R.; Brandon, Mark M.; True, Bradford G.

    2012-01-17

    A hearth furnace 10 for producing metallic iron material has a furnace housing 11 having a drying/preheat zone 12, a conversion zone 13, a fusion zone 14, and optionally a cooling zone 15, the conversion zone 13 is between the drying/preheat zone 12 and the fusion zone 14. A moving hearth 20 is positioned within the furnace housing 11. A hood or separation barrier 30 within at least a portion of the conversion zone 13, fusion zone 14 or both separates the fusion zone 14 into an upper region and a lower region with the lower region adjacent the hearth 20 and the upper region adjacent the lower region and spaced from the hearth 20. An injector introduces a gaseous reductant into the lower region adjacent the hearth 20. A combustion region may be formed above the hood or separation barrier.

  15. System and method for producing metallic iron

    DOEpatents

    Bleifuss, Rodney L; Englund, David J; Iwasaki, Iwao; Fosnacht, Donald R; Brandon, Mark M; True, Bradford G

    2013-09-17

    A hearth furnace for producing metallic iron material has a furnace housing having a drying/preheat zone, a conversion zone, a fusion zone, and optionally a cooling zone, the conversion zone is between the drying/preheat zone and the fusion zone. A moving hearth is positioned within the furnace housing. A hood or separation barrier within at least a portion of the conversion zone, fusion zone or both separates the fusion zone into an upper region and a lower region with the lower region adjacent the hearth and the upper region adjacent the lower region and spaced from the hearth. An injector introduces a gaseous reductant into the lower region adjacent the hearth. A combustion region may be formed above the hood or separation barrier.

  16. Field-scale transport and transformation of carboxymethylcellulose-stabilized nano zero-valent iron.

    PubMed

    Johnson, Richard L; Nurmi, James T; O'Brien Johnson, Graham S; Fan, Dimin; O'Brien Johnson, Reid L; Shi, Zhenqing; Salter-Blanc, Alexandra J; Tratnyek, Paul G; Lowry, Gregory V

    2013-02-01

    The fate of nano zerovalent iron (nZVI) during subsurface injection was examined using carboxymethylcellulose (CMC) stabilized nZVI in a very large three-dimensional physical model aquifer with detailed monitoring using multiple, complementary detection methods. A fluorescein tracer test in the aquifer plus laboratory column data suggested that the very-aggressive flow conditions necessary to achieve 2.5 m of nZVI transport could be obtained using a hydraulically constrained flow path between injection and extraction wells. However, total unoxidized nZVI was transported only about 1 m and <2% of the injected nZVI concentration reached that distance. The experimental data also indicated that groundwater flow changed during injection, likely due to hydrogen bubble formation, which diverted the nZVI away from the targeted flow path. The leading edge of the iron plume became fully oxidized during transport. However, within the plume, oxidation of nZVI decreased in a fashion consistent with progressive depletion of aquifer "reductant demand". To directly quantify the extent of nZVI transport, a spectrophotometric method was developed, and the results indicated that deployment of unoxidized nZVI for groundwater remediation will likely be difficult. PMID:23311327

  17. A field investigation of arsenic transport by colloidal iron oxides in the hyporheic zone

    NASA Astrophysics Data System (ADS)

    O'Carroll, D. M.; Hartland, A.; Larsen, J.; Andersen, M. S.

    2012-12-01

    Conceptual models concerning the fate of arsenic, and many other heavy metals, in aqueous environments including groundwater do not traditionally include colloids as potential facilitators of transport. However, there is significant evidence that heavy metals and oxyanions, including arsenic, preferentially partition into oxide phases. Iron oxides are commonly present as colloids (e.g. Ferrihydrite) and have the potential to mobilise and transport arsenic further than typically assumed. Interactions between Fe-oxides and natural organic matter (NOM) may be particularly significant in hyporheic sediments, given the comparatively high concentrations of dissolved organic carbon present and the presence of pronounced and dynamic redox fronts. Colloidal Fe-oxide stability may be enhanced by NOM surface coatings, potentially limiting colloid sedimentation and making encapsulated colloids more mobile. Furthermore, NOM is a significant agent driving As release, through the consumption of dissolved oxygen by microorganisms (leading to reductive dissolution of Fe-oxides in sediments. In this study the size-distribution and speciation of colloidal phases were studied beneath an ephemeral stream. We determined the proportions of Fe and As in colloidal fractions and determined the proportions held in complexes with NOM. Redox conditions went from aerobic, immediately beneath the stream, to anoxic and finally aerobic away from the stream and into the aquifer. This presentation will discuss dominant arsenic transport pathways including the possible importance of iron and natural organic colloids on arsenic transport.

  18. Influence of the electronic structure on the transport properties of some iron pnictides

    NASA Astrophysics Data System (ADS)

    Rullier-Albenque, Florence

    2016-01-01

    An important feature of the iron-based pnictides is their multi-band electronic structure with both electron and hole bands at the Fermi level. The size of these pockets can be changed by different types of substitution, resulting in a variety of original magnetic and electronic properties. The contributions of both types of carriers will thus have important consequences on the evolution of the transport properties versus temperature and doping. It has been pointed out that Hund's rule interaction plays a prominent role in the physics of these compounds by allowing a strong orbital differentiation between the 3d Fe orbitals. As a result, a description in terms of more or less correlated electrons was proposed and may have important consequences on the scattering lifetimes of the different carriers. Finally, the presence of very flat bands at the Fermi level may induce a semiconductor-like behavior, with a change in carrier concentration with temperature. In this paper, we will review the evolution of transport properties with chemical doping/substitution in iron pnictides. We will more particularly focus on the 122 family (Ba(Sr,Ca)Fe2As2) and the 111 LiFeAs compound for which sizeable single crystals required for transport measurements are available. The combined resistivity, Hall effect and magnetoresistance data will be analyzed in association with electronic structure calculations, angle-resolved photoemission measurements and quantum oscillations. In spite of the strong interplay between antiferromagnetism and superconductivity in most part of their phase diagram, direct signatures of spin fluctuations are difficult to identify in the transport properties of iron pnictides. We will show that measurements of the longitudinal magnetoresistance provide a powerful tool for studying the coupling between the charge carriers and the spin degrees of freedom.

  19. Use of electrophoresis for transporting nano-iron in porous media.

    PubMed

    Jones, Edward H; Reynolds, David A; Wood, A Lynn; Thomas, David G

    2011-01-01

    Research has been conducted to evaluate if electrophoresis could transport surface stabilized nanoscale zero-valent iron (nZVI) through fine grained sand with the intent of remediating a contaminant in situ. The experimental procedure involved determining the transport rates of polymer modified nZVI and hematite in fine grained sands under an applied electrical gradient under different physical and chemical conditions. Results indicated transport of polymer modified nZVI and hematite can be accomplished by electrophoresis, with rates found to be much higher than diffusion alone and comparable to those predicted by electrokinetic theory. This study indicates there is potential for this method to deliver polymer modified nZVI into contaminated zones within fine grained sands for the purpose of remediation. PMID:21449091

  20. Deficiency of a alpha-1-antitrypsin influences systemic iron homeostasis

    EPA Science Inventory

    Abstract Background: There is evidence that proteases and anti-proteases participate in the iron homeostasis of cells and living systems. We tested the postulate that alpha-1 antitrypsin (A1AT) polymorphism and the consequent deficiency of this anti-protease in humans are asso...

  1. 20. SIMILAR TO THE SYSTEM INSTALLED IN THE GREY IRON ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    20. SIMILAR TO THE SYSTEM INSTALLED IN THE GREY IRON FOUNDRY, MALLEABLE WORKERS FILLED MOLDS TRAVELING ON A CONVEYOR FROM LADLES ATTACHED TO OVERHEAD RAILS WHILE THEY STOOD ON A PLATFORM MOVING AT THE SAME SPEED AS THE CONVEYOR, CA. 1950 - Stockham Pipe & Fittings Company, 4000 Tenth Avenue North, Birmingham, Jefferson County, AL

  2. Iron toxicity in yeast.

    PubMed

    Wiśnicka, R; Krzepiłko, A; Wawryn, J; Biliński, T

    1997-01-01

    It has been found that yeast cells are sensitive to iron overload only when grown on glucose as a carbon source. Effective concentration of ferrous iron is much higher than that found in natural environments. Effects of ferrous iron are strictly oxygen dependent, what suggest that the formation of hydroxyl radicals in the Fenton reaction is a cause of the toxicity. Respiratory deficiency and pretreatment of cells with antimycin A prevent toxic effects in the late exponential phase of growth, whereas uncouplers and 2mM magnesium salts completely protect even the most vulnerable exponential cells. Generally, toxic effects correlate with the ability of cells to take up this metal. The results presented suggest that during ferrous iron overload iron is transported through the unspecific divalent cation uptake system which is known in fungi. The data suggest that recently described high and low affinity systems of iron uptake in yeast are the only source of iron in natural environments. PMID:9516981

  3. Method and system for producing metallic iron nuggets

    DOEpatents

    Iwasaki, Iwao; Lindgren, Andrew J.; Kiesel, Richard F.

    2013-06-25

    Method and system for producing metallic nuggets includes providing reducible mixture of reducing material (such as carbonaceous material) and reducible iron bearing material (such as iron oxide) that may be arranged in discrete portions, such as mounds or briquettes, on at least a portion of a hearth material layer (such as carbonaceous material). A coarse overlayer of carbonaceous material may be provided over at least some of the discrete portions. Heating the reducible mixture to 1425.degree. C. or 1400.degree. C. or 1375.degree. C. results in formation of an intermediate product of one or more metallic iron nuggets, which may have a sulfur content of less than 0.03%, and slag, which may have less than 5% mass MgO, which may have a ratio of percent by weight sulfur in the slag over percent by weight sulfur in the metallic nuggets of at least about 12 or at least about 15.

  4. Research on advanced transportation systems

    NASA Astrophysics Data System (ADS)

    Nagai, Hirokazu; Hashimoto, Ryouhei; Nosaka, Masataka; Koyari, Yukio; Yamada, Yoshio; Noda, Keiichirou; Shinohara, Suetsugu; Itou, Tetsuichi; Etou, Takao; Kaneko, Yutaka

    1992-08-01

    An overview of the researches on advanced space transportation systems is presented. Conceptual study is conducted on fly back boosters with expendable upper stage rocket systems assuming a launch capacity of 30 tons and returning to the launch site by the boosters, and prospect of their feasibility is obtained. Reviews are conducted on subjects as follows: (1) trial production of 10 tons sub scale engines for the purpose of acquiring hardware data and picking up technical problems for full scale 100 tons thrust engines using hydrocarbon fuels; (2) development techniques for advanced liquid propulsion systems from the aspects of development schedule, cost; (3) review of conventional technologies, and common use of component; (4) oxidant switching propulsion systems focusing on feasibility of Liquefied Air Cycle Engine (LACE) and Compressed Air Cycle Engine (CACE); (5) present status of slosh hydrogen manufacturing, storage, and handling; (6) construction of small high speed dynamometer for promoting research on mini pump development; (7) hybrid solid boosters under research all over the world as low-cost and clean propulsion systems; and (8) high performance solid propellant for upper stage and lower stage propulsion systems.

  5. F-box and leucine-rich repeat protein 5 (FBXL5) is required for maintenance of cellular and systemic iron homeostasis.

    PubMed

    Ruiz, Julio C; Walker, Scott D; Anderson, Sheila A; Eisenstein, Richard S; Bruick, Richard K

    2013-01-01

    Maintenance of cellular iron homeostasis requires post-transcriptional regulation of iron metabolism genes by iron regulatory protein 2 (IRP2). The hemerythrin-like domain of F-box and leucine-rich repeat protein 5 (FBXL5), an E3 ubiquitin ligase subunit, senses iron and oxygen availability and facilitates IRP2 degradation in iron replete cells. Disruption of the ubiquitously expressed murine Fbxl5 gene results in a failure to sense increased cellular iron availability, accompanied by constitutive IRP2 accumulation and misexpression of IRP2 target genes. FBXL5-null mice die during embryogenesis, although viability is restored by simultaneous deletion of the IRP2, but not IRP1, gene. Mice containing a single functional Fbxl5 allele behave like their wild type littermates when fed an iron-sufficient diet. However, unlike wild type mice that manifest decreased hematocrit and hemoglobin levels when fed a low-iron diet, Fbxl5 heterozygotes maintain normal hematologic values due to increased iron absorption. The responsiveness of IRP2 to low iron is specifically enhanced in the duodena of the heterozygotes and is accompanied by increased expression of the divalent metal transporter-1. These results confirm the role of FBXL5 in the in vivo maintenance of cellular and systemic iron homeostasis and reveal a privileged role for the intestine in their regulation by virtue of its unique FBXL5 iron sensitivity. PMID:23135277

  6. F-box and Leucine-rich Repeat Protein 5 (FBXL5) Is Required for Maintenance of Cellular and Systemic Iron Homeostasis*

    PubMed Central

    Ruiz, Julio C.; Walker, Scott D.; Anderson, Sheila A.; Eisenstein, Richard S.; Bruick, Richard K.

    2013-01-01

    Maintenance of cellular iron homeostasis requires post-transcriptional regulation of iron metabolism genes by iron regulatory protein 2 (IRP2). The hemerythrin-like domain of F-box and leucine-rich repeat protein 5 (FBXL5), an E3 ubiquitin ligase subunit, senses iron and oxygen availability and facilitates IRP2 degradation in iron replete cells. Disruption of the ubiquitously expressed murine Fbxl5 gene results in a failure to sense increased cellular iron availability, accompanied by constitutive IRP2 accumulation and misexpression of IRP2 target genes. FBXL5-null mice die during embryogenesis, although viability is restored by simultaneous deletion of the IRP2, but not IRP1, gene. Mice containing a single functional Fbxl5 allele behave like their wild type littermates when fed an iron-sufficient diet. However, unlike wild type mice that manifest decreased hematocrit and hemoglobin levels when fed a low-iron diet, Fbxl5 heterozygotes maintain normal hematologic values due to increased iron absorption. The responsiveness of IRP2 to low iron is specifically enhanced in the duodena of the heterozygotes and is accompanied by increased expression of the divalent metal transporter-1. These results confirm the role of FBXL5 in the in vivo maintenance of cellular and systemic iron homeostasis and reveal a privileged role for the intestine in their regulation by virtue of its unique FBXL5 iron sensitivity. PMID:23135277

  7. Influence of electrolyte and voltage on the direct current enhanced transport of iron nanoparticles in clay.

    PubMed

    Gomes, Helena I; Dias-Ferreira, Celia; Ribeiro, Alexandra B; Pamukcu, Sibel

    2014-03-01

    Zero valent iron nanoparticles (nZVI) transport for soil and groundwater remediation is slowed down or halted by aggregation or fast depletion in the soil pores. Direct electric current can enhance the transport of nZVI in low permeability soils. However operational factors, including pH, oxidation-reduction potential (ORP), voltage and ionic strength of the electrolyte can play an important role in the treatment effectiveness. Experiments were conducted to enhance polymer coated nZVI mobility in a model low permeability soil medium (kaolin clay) using low direct current. Different electrolytes of varying ionic strengths and initial pH and high nZVI concentrations were applied. Results showed that the nZVI transport is enhanced by direct current, even considering concentrations typical of field application that favor nanoparticle aggregation. However, the factors considered (pH, ORP, voltage and electrolyte) failed to explain the iron concentration variation. The electrolyte and its ionic strength proved to be significant for pH and ORP measured during the experiments, and therefore will affect aggregation and fast oxidation of the particles. PMID:24252496

  8. Brain iron homeostasis.

    PubMed

    Moos, Torben

    2002-11-01

    transferrin were, however, restricted to areas situated in close proximity to the ventricular and pial surfaces. In particular, transferrin injected into the ventricles was never observed in regions distant from the CSF. It was concluded that choroid plexus-derived transferrin is not likely to play a significant role for binding and transporting iron in the brain interstitium. Transferrin secretion from oligodendrocytes probably plays the key role in this process. In the third part of the thesis, the uptake of iron by neurons devoid of projections beyond the blood-brain barrier and glia is addressed. Given the fact that the demonstration of plasma proteins in brain sections can be hampered by several methodological factors, a mapping of the cellular distribution of transferrin in the brain was performed employing extensive use of tissue-processing and staining protocols. In order to aid in the understanding of cellular iron uptake in the intact brain, attempts were made to identify iron, transferrin, and transferrin receptors at the light microscopic level. Consistent with the widespread distribution of transferrin receptors in neurons, the ligand transferrin was also found in neurons throughout the CNS. When examined at high resolution, transferrin was found to be distributed to the cytoplasm of neurons, exhibiting a dotted appearance, which is probably consistent with a distribution in the endosomallysosomal system. In contrast to the consistent presence of transferrin receptors on neurons, it was not possible to detect transferrin receptors on glial cells. Related to these observations, the presence of non-transferrin-bound iron in the brain suggests that glial cells may take it up by a mechanism that does not involve the transferrin receptor. The widespread distribution of ferritin in glial cells clearly indicates that the glial cells acquire iron. Dietary iron-overload did not change the distribution of transferrin receptors or ferritin in the brain. By contrast, iron

  9. Use of a molecular decoy to segregate transport from antigenicity in the FrpB iron transporter from Neisseria meningitidis.

    PubMed

    Saleem, Muhammad; Prince, Stephen M; Rigby, Stephen E J; Imran, Muhammad; Patel, Hema; Chan, Hannah; Sanders, Holly; Maiden, Martin C J; Feavers, Ian M; Derrick, Jeremy P

    2013-01-01

    FrpB is an outer membrane transporter from Neisseria meningitidis, the causative agent of meningococcal meningitis. It is a member of the TonB-dependent transporter (TBDT) family and is responsible for iron uptake into the periplasm. FrpB is subject to a high degree of antigenic variation, principally through a region of hypervariable sequence exposed at the cell surface. From the crystal structures of two FrpB antigenic variants, we identify a bound ferric ion within the structure which induces structural changes on binding which are consistent with it being the transported substrate. Binding experiments, followed by elemental analysis, verified that FrpB binds Fe(3+) with high affinity. EPR spectra of the bound Fe(3+) ion confirmed that its chemical environment was consistent with that observed in the crystal structure. Fe(3+) binding was reduced or abolished on mutation of the Fe(3+)-chelating residues. FrpB orthologs were identified in other Gram-negative bacteria which showed absolute conservation of the coordinating residues, suggesting the existence of a specific TBDT sub-family dedicated to the transport of Fe(3+). The region of antigenic hypervariability lies in a separate, external sub-domain, whose structure is conserved in both the F3-3 and F5-1 variants, despite their sequence divergence. We conclude that the antigenic sub-domain has arisen separately as a result of immune selection pressure to distract the immune response from the primary transport function. This would enable FrpB to function as a transporter independently of antibody binding, by using the antigenic sub-domain as a 'molecular decoy' to distract immune surveillance. PMID:23457610

  10. Use of a Molecular Decoy to Segregate Transport from Antigenicity in the FrpB Iron Transporter from Neisseria meningitidis

    PubMed Central

    Saleem, Muhammad; Prince, Stephen M.; Rigby, Stephen E. J.; Imran, Muhammad; Patel, Hema; Chan, Hannah; Sanders, Holly; Maiden, Martin C. J.; Feavers, Ian M.; Derrick, Jeremy P.

    2013-01-01

    FrpB is an outer membrane transporter from Neisseria meningitidis, the causative agent of meningococcal meningitis. It is a member of the TonB-dependent transporter (TBDT) family and is responsible for iron uptake into the periplasm. FrpB is subject to a high degree of antigenic variation, principally through a region of hypervariable sequence exposed at the cell surface. From the crystal structures of two FrpB antigenic variants, we identify a bound ferric ion within the structure which induces structural changes on binding which are consistent with it being the transported substrate. Binding experiments, followed by elemental analysis, verified that FrpB binds Fe3+ with high affinity. EPR spectra of the bound Fe3+ ion confirmed that its chemical environment was consistent with that observed in the crystal structure. Fe3+ binding was reduced or abolished on mutation of the Fe3+-chelating residues. FrpB orthologs were identified in other Gram-negative bacteria which showed absolute conservation of the coordinating residues, suggesting the existence of a specific TBDT sub-family dedicated to the transport of Fe3+. The region of antigenic hypervariability lies in a separate, external sub-domain, whose structure is conserved in both the F3-3 and F5-1 variants, despite their sequence divergence. We conclude that the antigenic sub-domain has arisen separately as a result of immune selection pressure to distract the immune response from the primary transport function. This would enable FrpB to function as a transporter independently of antibody binding, by using the antigenic sub-domain as a ‘molecular decoy’ to distract immune surveillance. PMID:23457610

  11. THE EFFECT OF CHLORIDE AND ORTHOPHOSPHATE ON THE RELEASE OF IRON FROM A DRINKING WATER DISTRIBUTION SYSTEM CAST IRON PIPE

    EPA Science Inventory

    Colored water" describes the appearance of drinking water that contains suspended particulate iron although the actual suspension color may be light yellow to red depending on water chemistry and particle properties. The release of iron from distribution system materials such as...

  12. THE EFFECT OF CHLORIDE AND ORTHOPHOSPHATE ON THE RELEASE OF IRON FROM A DRINKING WATER DISTRIBUTION SYSTEM CAST IRON PIPE

    EPA Science Inventory

    "Colored water" describes the appearance of drinking water that contains suspended particulate iron although the actual suspension color may be light yellow to red depending on water chemistry and particle properties. The release of iron from distribution system materials such a...

  13. GEOCHEMISTRY OF SULFUR IN IRON CORROSION SCALES FOUND IN DRINKING WATER DISTRIBUTION SYSTEMS

    EPA Science Inventory

    Iron-sulfur geochemistry is important in many natural and engineered environments, including drinking water systems. In the anaerobic environment beneath scales of corroding iron drinking water distribution system pipes, sulfate reducing bacteria (SRB) produce sulfide from natu...

  14. The Yersiniabactin Transport System Is Critical for the Pathogenesis of Bubonic and Pneumonic Plague▿

    PubMed Central

    Fetherston, Jacqueline D.; Kirillina, Olga; Bobrov, Alexander G.; Paulley, James T.; Perry, Robert D.

    2010-01-01

    Iron acquisition from the host is an important step in the pathogenic process. While Yersinia pestis has multiple iron transporters, the yersiniabactin (Ybt) siderophore-dependent system plays a major role in iron acquisition in vitro and in vivo. In this study, we determined that the Ybt system is required for the use of iron bound by transferrin and lactoferrin and examined the importance of the Ybt system for virulence in mouse models of bubonic and pneumonic plague. Y. pestis mutants unable to either transport Ybt or synthesize the siderophore were both essentially avirulent via subcutaneous injection (bubonic plague model). Surprisingly, via intranasal instillation (pneumonic plague model), we saw a difference in the virulence of Ybt biosynthetic and transport mutants. Ybt biosynthetic mutants displayed an ∼24-fold-higher 50% lethal dose (LD50) than transport mutants. In contrast, under iron-restricted conditions in vitro, a Ybt transport mutant had a more severe growth defect than the Ybt biosynthetic mutant. Finally, a Δpgm mutant had a greater loss of virulence than the Ybt biosynthetic mutant, indicating that the 102-kb pgm locus encodes a virulence factor, in addition to Ybt, that plays a role in the pathogenesis of pneumonic plague. PMID:20160020

  15. Radioisotope thermoelectric generator transport trailer system

    NASA Astrophysics Data System (ADS)

    Ard, Kevin E.; King, David A.; Leigh, Harley; Satoh, Juli A.

    1995-01-01

    The Radioisotope Thermoelectric Generator (RTG) Transportation System, designated as System 100, comprises four major systems. The four major systems are designated as the Packaging System (System 120), Trailer System (System 140), Operations and Ancillary Equipment System (System 160), and Shipping and Receiving Facility Transport System (System 180). Packaging System (System 120), including the RTG packaging is licensed (regulatory) hardware; it is certified by the U.S. Department of Energy to be in accordance with Title 10, Code of Federal Regulations, Part 71 (10 CFR 71). System 140, System 160, and System 180 are nonlicensed (nonregulatory) hardware.

  16. Radioisotope thermoelectric generator transport trailer system

    SciTech Connect

    Ard, K.E.; King, D.A.; Leigh, H.; Satoh, J.A.

    1995-01-20

    The Radioisotope Thermoelectric Generator (RTG) Transportation System, designated as System 100, comprises four major systems. The four major systems are designated as the Packaging System (System 120), Trailer System (System 140), Operations and Ancillary Equipment System (System 160), and Shipping and Receiving Facility Transport System (System 180). Packaging System (System 120), including the RTG packaging is licensed (regulatory) hardware; it is certified by the U.S. Department of Energy to be in accordance with Title 10, {ital Code} {ital of} {ital Federal} {ital Regulations}, Part 71 (10 CFR 71). System 140, System 160, and System 180 are nonlicensed (nonregulatory) hardware. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}

  17. Urban Transportation Planning Short Course: Evaluation of Alternative Transportation Systems.

    ERIC Educational Resources Information Center

    Federal Highway Administration (DOT), Washington, DC.

    This urban transportation pamphlet delves into the roles of policy groups and technical staffs in evaluating alternative transportation plans, evaluation criteria, systems to evaluate, and evaluation procedures. The introduction admits the importance of subjective, but informed, judgment as an effective tool in weighing alternative transportation…

  18. Transport of carboxymethyl cellulose stabilized nanoscale zerovalent iron in porous media, an experimental and modeling study

    NASA Astrophysics Data System (ADS)

    Sleep, Brent; Mondal, Pulin; Furbacher, Paul; Cui, Ziteng; Krol, Magdalena

    2015-04-01

    Nano-scale zero valent iron (nZVI) is capable of reacting with a wide variety of groundwater contaminants. Therefore, during the last decade nZVI has received significant attention for application in subsurface remediation, particularly for sites contaminated with chlorinated compounds and heavy metals. However, due to agglomeration of the nZVI, delivery into the contaminated subsurface zones is challenging. Polymer stabilization of nZVI can enhance the mobility of the iron particles in the subsurface. In this study, a set of laboratory-scale transport experiments and numerical simulations were performed to evaluate carboxymethyl cellulose (CMC) polymer stabilized nZVI transport in porous media. Experiments were conducted in a two-dimensional water-saturated lab-scale glass-walled sandbox, uniformly packed with silica sand, to identify the effects of water specific discharge and CMC concentration on nZVI transport. Experiments were also performed using Lissamine Green B (LGB) dye as a non-reactive tracer to characterize the sand media. The CMC stabilized nZVI was synthesized freshly at a concentration of 1000 mg/L before each transport experiment. The synthesized CMC-nZVI mixture was characterized using transmission electron microscopy, dynamic light scattering, and UV-visual spectrophotometry. The movement of the LGB dye and nZVI in the sandbox during the experiments was monitored using time-lapsed images captured using a light source and a dark box. The transport of LGB, CMC, and CMC-nZVI was evaluated through analysis of the breakthrough curves at the outlet and the retained nZVI in the sandbox. The LGB, CMC, and nZVI transport was also modeled using a multiphase flow and transport model considering LGB and CMC as solutes, and nZVI as a colloid. Analysis of the breakthrough data showed that the mass recovery of LGB and CMC was greater than 95 % indicating conservative transport in silica sand. However, the mean residence time of CMC was significantly higher than

  19. Modeling Polymer Stabilized Nano-scale Zero Valent Iron Transport Experiments in Porous Media to Understand the Transport Behavior

    NASA Astrophysics Data System (ADS)

    Mondal, P.; Krol, M.; Sleep, B. E.

    2015-12-01

    A wide variety of groundwater contaminants can be treated with nano-scale zero valent iron (nZVI). However, delivery of nZVI in the subsurface to the treatment zones is challenging as the bare nZVI particles have a higher tendency to agglomerate. The subsurface mobility of nZVI can be enhanced by stabilizing nZVI with polymer, such as carboxymethyl cellulose (CMC). In this study, numerical simulations were conducted to evaluate CMC stabilized nZVI transport behavior in porous media. The numerical simulations were based on a set of laboratory-scale transport experiments that were conducted in a two-dimensional water-saturated glass-walled sandbox (length - 55 cm; height - 45 cm; width - 1.4 cm), uniformly packed with silica sand. In the transport experiments: CMC stabilized nZVI and a non-reactive dye tracer Lissamine Green B (LGB) were used; water specific discharge and CMC concentration were varied; movements of LGB, and CMC-nZVI in the sandbox were tracked using a camera, a light source and a dark box. The concentrations of LGB, CMC, and CMC-nZVI at the sandbox outlet were analyzed. A 2D multiphase flow and transport model was applied to simulate experimental results. The images from LGB dye transport experiments were used to determine the pore water velocities and media permeabilities in various layers in the sand box. These permeability values were used in the subsequent simulations of CMC-nZVI transport. The 2D compositional simulator, modified to include colloid filtration theory (CFT), treated CMC as a solute and nZVI as a colloid. The simulator included composition dependent viscosity to account for CMC injection and mixing, and attachment efficiency as a fitting parameter for nZVI transport modeling. In the experiments, LGB and CMC recoveries were greater than 95%; however, CMC residence time was significantly higher than the LGB residence time and the higher CMC concentration caused higher pressure drops in the sandbox. The nZVI recovery was lower than 40

  20. Phase stable RF transport system

    DOEpatents

    Curtin, Michael T.; Natter, Eckard F.; Denney, Peter M.

    1992-01-01

    An RF transport system delivers a phase-stable RF signal to a load, such as an RF cavity of a charged particle accelerator. A circuit generates a calibration signal at an odd multiple frequency of the RF signal where the calibration signal is superimposed with the RF signal on a common cable that connects the RF signal with the load. Signal isolating diplexers are located at both the RF signal source end and load end of the common cable to enable the calibration to be inserted and extracted from the cable signals without any affect on the RF signal. Any phase shift in the calibration signal during traverse of the common cable is then functionally related to the phase shift in the RF signal. The calibration phase shift is used to control a phase shifter for the RF signal to maintain a stable RF signal at the load.

  1. Classical transport in disordered systems

    NASA Astrophysics Data System (ADS)

    Papaioannou, Antonios

    This thesis reports on the manifestation of structural disorder on molecular transport and it consists of two parts. Part I discusses the relations between classical transport and the underlying structural complexity of the system. Both types of molecular diffusion, namely Gaussian and non- Gaussian are presented and the relevant time regimes are discussed. In addition the concept of structural universality is introduced and connected with the diffusion metrics. One of the most robust techniques for measuring molecular mean square displacements is magnetic resonance. This method requires encoding and subsequently reading out after an experimentally controlled time, a phase φ to the spins using magnetic field gradients. The main limitation for probing short diffusion lengths L(t) ˜ 1micro m with magnetic resonance is the requirement to encode and decode the phase φ in very short time intervals. Therefore, to probe such displacements a special probe was developed equipped with a gradient coil capable of delivering magnetic field gradients of approximately 90 G/cmA . The design of the probe is reported. Part I also includes a discussion of experiments of transport in two qualitatively different disordered phantoms and reports on a direct observation of universality in one-dimension. The results reveal the universal power law scaling of the diffusion coefficient at the long-time regime and illustrate the essence of structural universality by experimentally determining the structure correlation function of the phantoms. In addition, the scaling of the diffusive permeability of the phantoms with respect to the pore size is investigated. Additional work presented includes a detailed study of adsorption of methane gas in Vycor disordered glass. The techniques described in Part I of this thesis are widely used for measuring structural parameters of porous media, such as the surface-to-volume ratio or diffusive permeability. Part II of this thesis discusses the

  2. Manned transportation system study - Evaluation of candidate transportation architectures

    NASA Technical Reports Server (NTRS)

    Lance, Nicholas; Klemer, R.; Sooter, C.

    1992-01-01

    The overall evaluation process, the tool developed to perform the evaluation, and the evaluation results in determining the right approach to meet the nation's mannned transportation needs are presented. To address the various considerations, architecture sets consisting of the candidate transportation systems are constructed. As this methodology results in multiple architectures to examine, an architecture evaluation tool was developed to facilitate the evaluation of the architecture attribute values from the system values of the attributes.

  3. Integration of Genome-Scale Metabolic Nodels of Iron-Reducing Bacteria With Subsurface Flow and Geochemical Reactive Transport Models

    NASA Astrophysics Data System (ADS)

    Scheibe, T. D.; Mahadevan, R.; Fang, Y.; Garg, S.; Long, P. E.; Lovley, D. M.

    2008-12-01

    Several field and laboratory experiments have demonstrated that the growth and activity of iron-reducing bacteria can be stimulated in many subsurface environments by amendment of groundwater with a soluble electron donor. Under strong iron-reducing conditions, these organisms mediate reactions that can impact a wide range of subsurface contaminants including chlorinated hydrocarbons, metals, and radionuclides. Therefore there is strong interest in in-situ bioremediation as a potential technology for cleanup of contaminated aquifers. To evaluate and design bioremediation systems, as well as to evaluate the viability of monitored natural attenuation as an alternative, quantitative models of biogeochemically reactive transport are needed. To date, most such models represent microbial activity in terms of kinetic rate (e.g., Monod- type) formulations. Such models do not account for fundamental changes in microbial functionality (such as utilization of alternative respiratory pathways) that occur as the result of spatial and temporal variations in the geochemical environment experienced by microorganisms. Constraint-based genome-scale in silico models of microbial metabolism present an alternative to simplified rate formulations that provide flexibility to account for changes in microbial function in response to local geochemical conditions. We have developed and applied a methodology for coupling a constraint-based in silico model of Geobacter sulfurreducens with a conventional model of groundwater flow, transport, and geochemical reaction. Two uses of the in silico model are tested: 1) incorporation of modified microbial growth yield coefficients based on the in silico model, and 2) variation of reaction rates in a reactive transport model based on in silico modeling of a range of local geochemical conditions. Preliminary results from this integrated model will be presented.

  4. Transport of nano zero-valent iron supported by mesoporous silica microspheres in porous media.

    PubMed

    Yang, Zhangmei; Qiu, Xinhong; Fang, Zhanqiang; Pokeung, Tsang

    2015-01-01

    Effective in situ remediation of groundwater requires the successful delivery of reactive iron particles through sand. However, the agglomeration of nano zero-valent iron (NZVI) particles limits the migration distance, which inhibits their usefulness. In the study described herein, NZVI supported by mesoporous silica microspheres covered with FeOOH (SiO2@FeOOH@Fe) was synthesized, and its mobility was demonstrated on the basis of transport in porous media. Degradation of decabromodiphenyl ether (BDE209) was more efficient by SiO2@FeOOH@Fe than by 'bare' NZVI. Breakthrough curves and mass recovery showed the mobility of SiO2@FeOOH@Fe in granular media was better than that of bare NZVI. It increased greatly in the presence of natural organic matter (NOM) and decreased when high Ca2+ and Mg2+ concentrations were encountered. Analysis of the transport data on the basis of filtration theory showed diffusion to be the main mechanism for particle removal in silicon sand. Increasing the NOM may decrease agglomeration of the grains of sand, which has a positive effect on the mobility of SiO2@FeOOH@Fe. Presumably, increasing the concentrations of Ca2+ and Mg2+ compresses the diffuse double layer of SiO2@FeOOH@Fe, resulting in a reduction of mobility. PMID:26067499

  5. TonB Energy Transduction Systems of Riemerella anatipestifer Are Required for Iron and Hemin Utilization

    PubMed Central

    Liao, HeBin; Cheng, XingJun; Zhu, DeKang; Wang, MingShu; Jia, RenYong; Chen, Shun; Chen, XiaoYue; Biville, Francis; Liu, MaFeng; Cheng, AnChun

    2015-01-01

    Riemerella anatipestifer (R. anatipestifer) is one of the most important pathogens in ducks. The bacteria causes acute or chronic septicemia characterized by fibrinous pericarditis and meningitis. The R. anatipestifer genome encodes multiple iron/hemin-uptake systems that facilitate adaptation to iron-limited host environments. These systems include several TonB-dependent transporters and three TonB proteins responsible for energy transduction. These three tonB genes are present in all the R. anatipestifer genomes sequenced so far. Two of these genes are contained within the exbB-exbD-tonB1 and exbB-exbD-exbD-tonB2 operons. The third, tonB3, forms a monocistronic transcription unit. The inability to recover derivatives deleted for this gene suggests its product is essential for R. anatipestifer growth. Here, we show that deletion of tonB1 had no effect on hemin uptake of R. anatipestifer, though disruption of tonB2 strongly decreases hemin uptake, and disruption of both tonB1 and tonB2 abolishes the transport of exogenously added hemin. The ability of R. anatipestifer to grow on iron-depleted medium is decreased by tonB2 but not tonB1 disruption. When expressed in an E. coli model strain, the TonB1 complex, TonB2 complex, and TonB3 protein from R. anatipestifer cannot energize heterologous hemin transporters. Further, only the TonB1 complex can energize a R. anatipestifer hemin transporter when co-expressed in an E. coli model strain. PMID:26017672

  6. A new analytical approach to understanding nanoscale lead-iron interactions in drinking water distribution systems.

    PubMed

    Trueman, Benjamin F; Gagnon, Graham A

    2016-07-01

    High levels of iron in distributed drinking water often accompany elevated lead release from lead service lines and other plumbing. Lead-iron interactions in drinking water distribution systems are hypothesized to be the result of adsorption and transport of lead by iron oxide particles. This mechanism was explored using point-of-use drinking water samples characterized by size exclusion chromatography with UV and multi-element (ICP-MS) detection. In separations on two different stationary phases, high apparent molecular weight (>669 kDa) elution profiles for (56)Fe and (208)Pb were strongly correlated (average R(2)=0.96, N=73 samples representing 23 single-unit residences). Moreover, (56)Fe and (208)Pb peak areas exhibited an apparent linear dependence (R(2)=0.82), consistent with mobilization of lead via adsorption to colloidal particles rich in iron. A UV254 absorbance peak, coincident with high molecular weight (56)Fe and (208)Pb, implied that natural organic matter was interacting with the hypothesized colloidal species. High molecular weight UV254 peak areas were correlated with both (56)Fe and (208)Pb peak areas (R(2)=0.87 and 0.58, respectively). On average, 45% (std. dev. 10%) of total lead occurred in the size range 0.05-0.45 μm. PMID:26971028

  7. Transport of iron oxide nanoparticles in saturated porous media: a large-scale 3D study

    NASA Astrophysics Data System (ADS)

    Velimirovic, Milica; Schmid, Doris; Micić, Vesna; Miyajima, Kumiko; Klaas, Norbert; Braun, Jürgen; Bosch, Julian; Meckenstock, Rainer; von der Kammer, Frank; Hofmann, Thilo

    2016-04-01

    Iron oxide nanoparticles (FeOxNp) have a high potential as electron acceptor for in situ microbial oxidation of a wide range of recalcitrant groundwater contaminants (Bosch et al., 2010). Tosco et al. (2012) reported on high colloidal stability of FeOxNp dispersed in water, their low deposition behavior, and consequently improved transport in column experiments compared to extensively studied zerovalent iron nanoparticles. However, determination of FeOxNp transport behavior at the field-relevant conditions has not been done before. The present work is aimed to evaluate different complementary methods for detection, quantification and transport characterization of FeOxNp in a large-scale three-dimensional (3D) model aquifer. Prior to that, batch-scale experiments were performed in order to elucidate the potential of the selected methods for direct and indirect characterization and detection of FeOxNp. Direct methods included measurements of particle size distribution, particle concentration, Fetot content and turbidity of the FeOxNp suspension. Indirect methods included measurements of particle zeta potential, as well as TOC content and pH of the FeOxNp suspension. The results of the batch experiments indicated that the most suitable approach for detecting and quantifying FeOxNp was measuring Fetot content and suspension turbidity, as well as particle size determined using dynamic light scattering principle. These complementary methods were further applied in a large-scale 3D study containing medium and coarse sand in order to 1) assess the transport of FeOxNp in saturated porous medium during injection (VFeOx = 6 m3, cparticle = 20 g/L, Qinj = 0.7 m3/h), and 2) illustrate their spatial distribution after injection. The outcomes of the large-scale 3D study confirmed that FeOxNp transport can be successfully investigated applying complementary methods. Monitoring data including Fetot content, turbidity and particle size showed the transport of particles towards the

  8. Overlap of copper and iron uptake systems in mitochondria in Saccharomyces cerevisiae

    PubMed Central

    Wang, Jing; Gammon, Micah G.; Maynard, Margaret K.; White, Olivia L.; Cobine, Jai A.; Mahone, Wilkerson K.

    2016-01-01

    In Saccharomyces cerevisiae, the mitochondrial carrier family protein Pic2 imports copper into the matrix. Deletion of PIC2 causes defects in mitochondrial copper uptake and copper-dependent growth phenotypes owing to decreased cytochrome c oxidase activity. However, copper import is not completely eliminated in this mutant, so alternative transport systems must exist. Deletion of MRS3, a component of the iron import machinery, also causes a copper-dependent growth defect on non-fermentable carbon. Deletion of both PIC2 and MRS3 led to a more severe respiratory growth defect than either individual mutant. In addition, MRS3 expressed from a high copy number vector was able to suppress the oxygen consumption and copper uptake defects of a strain lacking PIC2. When expressed in Lactococcus lactis, Mrs3 mediated copper and iron import. Finally, a PIC2 and MRS3 double mutant prevented the copper-dependent activation of a heterologously expressed copper sensor in the mitochondrial intermembrane space. Taken together, these data support a role for the iron transporter Mrs3 in copper import into the mitochondrial matrix. PMID:26763345

  9. Enhanced transport of Si-coated nanoscale zero-valent iron particles in porous media.

    PubMed

    HonetschlÄgerová, Lenka; Janouškovcová, Petra; Kubal, Martin

    2016-01-01

    Laboratory column experiments were conducted to evaluate the effect of previously described silica coating method on the transport of nanoscale zero-valent iron (nZVI) in porous media. The silica coating method showed the potential to prevent the agglomeration of nZVI. Transport experiments were conducted using laboratory-scale sand-packed columns at conditions that were very similar of natural groundwater. Transport properties of non-coated and silica-coated nZVI are investigated in columns of 40 cm length, which were filled with porous media. A suspension was injected in three different Fe particle concentrations (100, 500, and 1000 mg/L) at flow 5  mL/min. Experimental results were compared using nanoparticle attachment efficiency and travel distances which were calculated by classical particle filtration theory. It was found that non-coated particles were essentially immobile in porous media. In contrast, silica-coated particles showed significant transport distances at the tested conditions. Results of this study suggest that silica can increase nZVI mobility in the subsurface. PMID:26582314

  10. Extracting archaeal populations from iron oxidizing systems

    NASA Astrophysics Data System (ADS)

    Whitmore, L. M.; Hutchison, J.; Chrisler, W.; Jay, Z.; Moran, J.; Inskeep, W.; Kreuzer, H.

    2013-12-01

    Unique environments in Yellowstone National Park offer exceptional conditions for studying microorganisms in extreme and constrained systems. However, samples from some extreme systems often contain inorganic components that pose complications during microbial and molecular analysis. Several archaeal species are found in acidic, geothermal ferric-oxyhydroxide mats; these species have been shown to adhere to mineral surfaces in flocculated colonies. For optimal microbial analysis, (microscopy, flow cytometry, genomic extractions, proteomic analysis, stable isotope analysis, and others), improved techniques are needed to better facilitate cell detachment and separation from mineral surfaces. As a requirement, these techniques must preserve cell structure while simultaneously minimizing organic carryover to downstream analysis. Several methods have been developed for removing sediments from mixed prokaryotic populations, including ultra-centrifugation, nycodenz gradient, sucrose cushions, and cell straining. In this study we conduct a comparative analysis of mechanisms used to detach archaeal cell populations from the mineral interface. Specifically, we evaluated mechanical and chemical approaches for cell separation and homogenization. Methods were compared using confocal microscopy, flow cytometry analyses, and real-time PCR detection. The methodology and approaches identified will be used to optimize biomass collection from environmental specimens or isolates grown with solid phases.

  11. Transport and viability of Escherichia coli cells in clean and iron oxide coated sand following coating with silver nanoparticles.

    PubMed

    Ngwenya, Bryne T; Curry, Philip; Kapetas, Leon

    2015-08-01

    A mechanistic understanding of processes controlling the transport and viability of bacteria in porous media is critical for designing in situ bioremediation and microbiological water decontamination programs. We investigated the combined influence of coating sand with iron oxide and silver nanoparticles on the transport and viability of Escherichia coli cells under saturated conditions. Results showed that iron oxide coatings increase cell deposition which was generally reversed by silver nanoparticle coatings in the early stages of injection. These observations are consistent with short-term, particle surface charge controls on bacteria transport, where a negatively charged surface induced by silver nanoparticles reverses the positive charge due to iron oxide coatings, but columns eventually recovered irreversible cell deposition. Silver nanoparticle coatings significantly increased cell inactivation during transit through the columns. However, when viability data is normalised to volume throughput, only a small improvement in cell inactivation is observed for silver nanoparticle coated sands relative to iron oxide coating alone. This counterintuitive result underscores the importance of net surface charge in controlling cell transport and inactivation and implies that the extra cost for implementing silver nanoparticle coatings on porous beds coated with iron oxides may not be justified in designing point of use water filters in low income countries. PMID:26042624

  12. The barium iron ruthenium oxide system

    NASA Technical Reports Server (NTRS)

    Kemmler-Sack, S.; Ehmann, A.

    1986-01-01

    In the system BaFe(1-x)Ru(x)O(3-y), three phases, separated by immiscibility gaps, are present: an Fe-rich phase (x = 0 to 0.75) with hexagonal BaTiO3 structure (6H; sequence (hcc)2), a Ru-rich phase (x = 0.9) of hexagonal 4H-type (sequence (hc)2), and the pure Ru compounds BaRuO3 with rhombohedral 9R structure (sequence (hhc)3). By vibrational spectroscopic investigations in the 6H phase a transition from n-type semiconduction (Fe-rich compounds with complete O lattice) can be detected. The 4H and 9R stacking polytypes are good, metal-like conductors. The lattice parameters are given.

  13. The Newcastle geothermal system, Iron County, Utah

    SciTech Connect

    Blackett, R.E.; Shubat, M.A.; Bishop, C.E. ); Chapman, D.S.; Forster, C.B.; Schlinger, C.M. . Dept. of Geology and Geophysics)

    1990-03-01

    Geological, geophysical and geochemical studies contributed to conceptual hydrologic model of the blind'' (no surface expression), moderate-temperature (greater than 130{degree}C) Newcastle geothermal system, located in the Basin and Range-Colorado Plateau transition zone of southwestern Utah. Temperature gradient measurements define a thermal anomaly centered near the surface trace of the range-bounding Antelope Range fault with and elongate dissipative plume extending north into the adjacent Escalante Valley. Spontaneous potential and resistivity surveys sharply define the geometry of the dominant upflow zone (not yet explored), indicating that most of the thermal fluid issues form a short segment along the Antelope Range fault and discharges into a gently-dipping aquifer. Production wells show that this aquifer lies at a depth between 85 and 95 meter. Electrical surveys also show that some leakage of thermal fluid occurs over a 1.5 km (minimum) interval along the trace of the Antelope Range fault. Major element, oxygen and hydrogen isotopic analyses of water samples indicate that the thermal fluid is a mixture of meteoric water derived from recharge areas in the Pine Valley Mountains and cold, shallow groundwater. A northwest-southeast trending system of faults, encompassing a zone of increased fracture permeability, collects meteoric water from the recharge area, allows circulation to a depth of 3 to 5 kilometers, and intersects the northeast-striking Antelope Range fault. We postulate that mineral precipitates form a seal along the Antelope Range fault, preventing the discharge of thermal fluids into basin-fill sediments at depth, and allowing heated fluid to approach the surface. Eventually, continued mineral deposition could result in the development of hot springs at the ground surface.

  14. Expression of the two mRNA isoforms of the iron transporter Nramp2/DMTI in mice and function of the iron responsive element.

    PubMed Central

    Tchernitchko, Dimitri; Bourgeois, Monique; Martin, Marie-Elise; Beaumont, Carole

    2002-01-01

    Nramp2/DMT1 is a transmembrane proton-coupled Fe(2+) transporter. Two different mRNAs are generated by alternative splicing; isoform I contains an iron responsive element (IRE), whereas isoform II does not. They encode two proteins differing at their C-terminal end and by their subcellular localization. IRE-mediated stabilization of isoform I mRNA is thought to stimulate DMT1 expression in response to iron deficiency. We have measured the two mRNAs by real-time quantitative PCR in several mouse tissues, in normal conditions or following injection of phenylhydrazine, a potent haemolytic agent. Isoform I mRNA is expressed in the duodenum and is induced by stimulation of erythropoiesis, whereas the non-IRE isoform is mostly induced in erythropoietic spleen. Surprisingly, both isoforms are highly expressed in the kidney and are not regulated by erythropoiesis. To evaluate the role of the IRE in regulating isoform I mRNA stability, in response to variations in cell iron status, several constructs were made in pCDNA3 with either a normal or a mutated IRE placed at the 3' end of a stable mRNA. These constructs were transfected into HT29 cells and mRNAs were analysed after growing cells in the presence or absence of exogenous iron. There was no difference in the level of expression of the different messages, suggesting that the IRE does not regulate stability of isoform I mRNA. The half-life of the endogenous IRE-mRNA was also measured following actinomycin D addition in iron- or desferrioxamine-treated cells. Decay of the mRNA was very similar in both conditions. These results suggest that additional transcriptional regulations at the promoter level, or iron-dependent regulation of alternative splicing are likely to participate in the induction of isoform I mRNA by iron deficiency. PMID:11964145

  15. A National MagLev Transportation System

    NASA Technical Reports Server (NTRS)

    Wright, Michael R.

    2003-01-01

    The case for a national high-speed magnetic-levitation (MagLev) transportation system is presented. Focus is on current issues facing the country, such as national security, the economy, transportation, technology, and the environment. NASA s research into MagLev technology for launch assist is also highlighted. Further, current socio-cultural norms regarding motor-vehicle-based transportation systems are questioned in light of the problems currently facing the U.S. The multidisciplinary benefits of a long-distance MagLev system support the idea that such a system would be an important element of a truly multimodal U.S. transportation infrastructure.

  16. Levonorgestrel-releasing intrauterine system and iron overload syndrome.

    PubMed

    Vieira da Motta, Marcia; Vieira da Motta, Eduardo

    2013-01-01

    Severe fatigue is a common complaint among patients. This report presents a clinical case of a woman complaining of fatigue associated with diarrhea and myalgia that were first attributed to emotional stress and depression. Initially, the patient was diagnosed with chronic fatigue and irritable bowel syndrome. The patient followed nutritional and physical exercise programs without any improvement. Other clinical conditions, such as nutritional deficiencies, endocrine dysfunctions, autoimmune diseases and neoplasias, were then assessed. During clinical investigation, serum ferritin and iron levels were abnormally elevated despite normal hemoglobin levels, which pointed to an iron overload syndrome later diagnosed as hemochromatosis. It is possible that the symptoms were triggered by the amenorrhea caused by the levonorgestrel-releasing intrauterine system used for contraception. PMID:23843714

  17. Regulation of Brain Iron and Copper Homeostasis by Brain Barrier Systems: Implication in Neurodegenerative Diseases

    PubMed Central

    Zheng, Wei; Monnot, Andrew D.

    2011-01-01

    Iron (Fe) and copper (Cu) are essential to neuronal function; excess or deficiency of either is known to underlie the pathoetiology of several commonly known neurodegenerative disorders. This delicate balance of Fe and Cu in the central milieu is maintained by the brain barrier systems, i.e., the blood-brain barrier (BBB) between the blood and brain interstitial fluid and the blood- cerebrospinal fluid barrier (BCB) between the blood and cerebrospinal fluid (CSF). This review provides a concise description on the structural and functional characteristics of the brain barrier systems. Current understanding of Fe and Cu transport across the brain barriers is thoroughly examined, with major focuses on whether the BBB and BCB coordinate the direction of Fe and Cu fluxes between the blood and brain/CSF. In particular, the mechanism by which pertinent metal transporters in the barriers, such as the transferrin receptor (TfR), divalent metal transporter (DMT1), copper transporter (CTR1), ATP7A/B, and ferroportin (FPN), regulate metal movement across the barriers is explored. Finally, the detrimental consequences of dysfunctional metal transport by brain barriers, as a result of endogenous disorders or exogenous insults, are discussed. Understanding the regulation of Fe and Cu homeostasis in the central nervous system aids in the design of new drugs targeted on the regulatory proteins at the brain barriers for the treatment of metal’s deficiency or overload-related neurological diseases. PMID:22115751

  18. Dictyostelium Nramp1, which is structurally and functionally similar to mammalian DMT1 transporter, mediates phagosomal iron efflux

    PubMed Central

    Buracco, Simona; Peracino, Barbara; Cinquetti, Raffaella; Signoretto, Elena; Vollero, Alessandra; Imperiali, Francesca; Castagna, Michela; Bossi, Elena; Bozzaro, Salvatore

    2015-01-01

    ABSTRACT The Nramp (Slc11) protein family is widespread in bacteria and eukaryotes, and mediates transport of divalent metals across cellular membranes. The social amoeba Dictyostelium discoideum has two Nramp proteins. Nramp1, like its mammalian ortholog (SLC11A1), is recruited to phagosomal and macropinosomal membranes, and confers resistance to pathogenic bacteria. Nramp2 is located exclusively in the contractile vacuole membrane and controls, synergistically with Nramp1, iron homeostasis. It has long been debated whether mammalian Nramp1 mediates iron import or export from phagosomes. By selectively loading the iron-chelating fluorochrome calcein in macropinosomes, we show that Dictyostelium Nramp1 mediates iron efflux from macropinosomes in vivo. To gain insight in ion selectivity and the transport mechanism, the proteins were expressed in Xenopus oocytes. Using a novel assay with calcein, and electrophysiological and radiochemical assays, we show that Nramp1, similar to rat DMT1 (also known as SLC11A2), transports Fe2+ and manganese, not Fe3+ or copper. Metal ion transport is electrogenic and proton dependent. By contrast, Nramp2 transports only Fe2+ in a non-electrogenic and proton-independent way. These differences reflect evolutionary divergence of the prototypical Nramp2 protein sequence compared to the archetypical Nramp1 and DMT1 proteins. PMID:26208637

  19. Dictyostelium Nramp1, which is structurally and functionally similar to mammalian DMT1 transporter, mediates phagosomal iron efflux.

    PubMed

    Buracco, Simona; Peracino, Barbara; Cinquetti, Raffaella; Signoretto, Elena; Vollero, Alessandra; Imperiali, Francesca; Castagna, Michela; Bossi, Elena; Bozzaro, Salvatore

    2015-09-01

    The Nramp (Slc11) protein family is widespread in bacteria and eukaryotes, and mediates transport of divalent metals across cellular membranes. The social amoeba Dictyostelium discoideum has two Nramp proteins. Nramp1, like its mammalian ortholog (SLC11A1), is recruited to phagosomal and macropinosomal membranes, and confers resistance to pathogenic bacteria. Nramp2 is located exclusively in the contractile vacuole membrane and controls, synergistically with Nramp1, iron homeostasis. It has long been debated whether mammalian Nramp1 mediates iron import or export from phagosomes. By selectively loading the iron-chelating fluorochrome calcein in macropinosomes, we show that Dictyostelium Nramp1 mediates iron efflux from macropinosomes in vivo. To gain insight in ion selectivity and the transport mechanism, the proteins were expressed in Xenopus oocytes. Using a novel assay with calcein, and electrophysiological and radiochemical assays, we show that Nramp1, similar to rat DMT1 (also known as SLC11A2), transports Fe(2+) and manganese, not Fe(3+) or copper. Metal ion transport is electrogenic and proton dependent. By contrast, Nramp2 transports only Fe(2+) in a non-electrogenic and proton-independent way. These differences reflect evolutionary divergence of the prototypical Nramp2 protein sequence compared to the archetypical Nramp1 and DMT1 proteins. PMID:26208637

  20. Moffett Field Funnel and Gate TCE Treatment System: Interpretation of Field Performance using Reactive Transport Modeling

    SciTech Connect

    Yabusaki, Steven B.; Cantrell, Kirk J.; Sass, B. M.

    2001-06-30

    A multicomponent reactive transport simulator was used to understand the behavior of chemical components, including TCE and cis-1,2-DCE, in groundwater transported through the pilot-scale funnel and gate chemical treatment system at Moffett Field, California. Field observations indicated that zero-valent iron emplaced in the gate to effect the destruction of chlorinated hydrocarbons also resulted in increases in pH and hydrocarbons, as well as decreases in EH, alkalinity, dissolved O2 and CO2, and major ions (i.e., Ca, Mg, Cl, sulfate, nitrate). Of concern are chemical transformations that may reduce the effectiveness or longevity of the iron cell and/or create secondary contaminants. A coupled model of transport and reaction processes was developed to account for mobile and immobile components undergoing equilibrium and kinetic reactions including TCE degradation, parallel iron dissolution reactions, precipitation of secondary minerals, and complexation reactions. The model reproduced solution chemistry observed in the iron cell using reaction parameters from the literature and laboratory studies. Mineral precipitation in the iron zone, which is critical to correctly predicting the aqueous concentrations, was predicted to account for up to 3 percent additional mineral volume annually. Interplay between rates of transport and rates of reaction in the field was key to understanding system behavior.

  1. Divalent metal transporter 1 regulates iron-mediated ROS and pancreatic β cell fate in response to cytokines.

    PubMed

    Hansen, Jakob Bondo; Tonnesen, Morten Fog; Madsen, Andreas Nygaard; Hagedorn, Peter H; Friberg, Josefine; Grunnet, Lars Groth; Heller, R Scott; Nielsen, Anja Østergren; Størling, Joachim; Baeyens, Luc; Anker-Kitai, Leeat; Qvortrup, Klaus; Bouwens, Luc; Efrat, Shimon; Aalund, Mogens; Andrews, Nancy C; Billestrup, Nils; Karlsen, Allan E; Holst, Birgitte; Pociot, Flemming; Mandrup-Poulsen, Thomas

    2012-10-01

    Reactive oxygen species (ROS) contribute to target-cell damage in inflammatory and iron-overload diseases. Little is known about iron transport regulation during inflammatory attack. Through a combination of in vitro and in vivo studies, we show that the proinflammatory cytokine IL-1β induces divalent metal transporter 1 (DMT1) expression correlating with increased β cell iron content and ROS production. Iron chelation and siRNA and genetic knockdown of DMT1 expression reduce cytokine-induced ROS formation and cell death. Glucose-stimulated insulin secretion in the absence of cytokines in Dmt1 knockout islets is defective, highlighting a physiological role of iron and ROS in the regulation of insulin secretion. Dmt1 knockout mice are protected against multiple low-dose streptozotocin and high-fat diet-induced glucose intolerance, models of type 1 and type 2 diabetes, respectively. Thus, β cells become prone to ROS-mediated inflammatory damage via aberrant cellular iron metabolism, a finding with potential general cellular implications. PMID:23000401

  2. High P-T diffusive transport properties of liquid iron alloys and peridotite melt

    NASA Astrophysics Data System (ADS)

    Posner, E. S.; Rubie, D. C.; Frost, D. J.; Vlček, V.; Steinle-Neumann, G.

    2015-12-01

    Diffusive transport properties of peridotite melt and molten iron alloys at high pressures and temperatures are important for understanding large-scale geodynamic processes and thermochemical evolution of planetary interiors, such as the time and length scales of metal-silicate equilibration during core formation and chemical exchange across core-mantle boundaries during cooling. In order to determine the pressure and temperature dependence of diffusion in these geologically relevant liquids, we have conducted experiments of Si, O, and Cr diffusion in liquid iron over the P-T range of 1.5—18 GPa and 1850—2450 K, and Si, O, Mg, Ca tracer and Ni, Co chemical diffusion in peridotite liquids over the P-T range of 4—24 GPa and 2248—2623 K in a multi-anvil apparatus. Our results show a very small pressure dependence (< 1 cm3/mol) of alloying element diffusion (Si, O, Cr) in liquid iron over the P-T range of the study and remarkably good consistency with first principles calculations (Pozzo et al. 2013. Phys. Rev. B 87, 014110; Ichikawa and Tsuchiya. 2015. Phys. Earth Planet. Inter., in press) when extrapolated to outer core conditions. Diffusion rates of Si, O, Ca, Mg, Ni, Co in silicate melt decrease with increasing pressure to a minimum at approximately 10 GPa. An anomalous pressure effect is observed above ~10 GPa such that diffusivities rapidly increase with increasing pressure for all elements to a maximum at ~12 GPa, consistent with previous work on peridotite viscosity to 13 GPa (Liebske et al. 2005. Earth Planet. Sci. Lett. 240, 589). Above ~12 GPa, diffusivities decrease with increasing pressure to 24 GPa. Peridotite melt viscosities calculated using the Eyring relation, oxygen self-diffusion rates, and average jump distance (λ) of 5.4 nm yield ~0.01 Pa s at 24 GPa and 2423 - 2623 K.

  3. Molecular and Evolutionary Analysis of NEAr-Iron Transporter (NEAT) Domains

    PubMed Central

    Honsa, Erin S.; Maresso, Anthony W.; Highlander, Sarah K.

    2014-01-01

    Iron is essential for bacterial survival, being required for numerous biological processes. NEAr-iron Transporter (NEAT) domains have been studied in pathogenic Gram-positive bacteria to understand how their proteins obtain heme as an iron source during infection. While a 2002 study initially discovered and annotated the NEAT domain encoded by the genomes of several Gram-positive bacteria, there remains a scarcity of information regarding the conservation and distribution of NEAT domains throughout the bacterial kingdom, and whether these domains are restricted to pathogenic bacteria. This study aims to expand upon initial bioinformatics analysis of predicted NEAT domains, by exploring their evolution and conserved function. This information was used to identify new candidate domains in both pathogenic and nonpathogenic organisms. We also searched metagenomic datasets, specifically sequence from the Human Microbiome Project. Here, we report a comprehensive phylogenetic analysis of 343 NEAT domains, encoded by Gram-positive bacteria, mostly within the phylum Firmicutes, with the exception of Eggerthella sp. (Actinobacteria) and an unclassified Mollicutes bacterium (Tenericutes). No new NEAT sequences were identified in the HMP dataset. We detected specific groups of NEAT domains based on phylogeny of protein sequences, including a cluster of novel clostridial NEAT domains. We also identified environmental and soil organisms that encode putative NEAT proteins. Biochemical analysis of heme binding by a NEAT domain from a protein encoded by the soil-dwelling organism Paenibacillus polymyxa demonstrated that the domain is homologous in function to NEAT domains encoded by pathogenic bacteria. Together, this study provides the first global bioinformatics analysis and phylogenetic evidence that NEAT domains have a strong conservation of function, despite group-specific differences at the amino acid level. These findings will provide information useful for future projects

  4. AtNRAMP3, a multispecific vacuolar metal transporter involved in plant responses to iron deficiency.

    PubMed

    Thomine, Sébastien; Lelièvre, Françoise; Debarbieux, Elise; Schroeder, Julian I; Barbier-Brygoo, Hélène

    2003-06-01

    Metal homeostasis is critical for the survival of living organisms, and metal transporters play central roles in maintaining metal homeostasis in the living cells. We have investigated the function of a metal transporter of the NRAMP family, AtNRAMP3, in Arabidopsis thaliana. A previous study showed that AtNRAMP3 expression is upregulated by iron (Fe) starvation and that AtNRAMP3 protein can transport Fe. In the present study, we used AtNRAMP3 promoter beta-glucoronidase (GUS) fusions to show that AtNRAMP3 is expressed in the vascular bundles of roots, stems, and leaves under Fe-sufficient conditions. This suggests a function in long-distance metal transport within the plant. Under Fe-starvation conditions, the GUS activity driven by the AtNRAMP3 promoter is upregulated without any change in the expression pattern. We analyze the impact of AtNRAMP3 disruption and overexpression on metal accumulation in plants. Under Fe-sufficient conditions, AtNRAMP3 overexpression or disruption does not lead to any change in the plant metal content. Upon Fe starvation, AtNRAMP3 disruption leads to increased accumulation of manganese (Mn) and zinc (Zn) in the roots, whereas AtNRAMP3 overexpression downregulates Mn accumulation. In addition, overexpression of AtNRAMP3 downregulates the expression of the primary Fe uptake transporter IRT1 and of the root ferric chelate reductase FRO2. Expression of AtNRAMP3::GFP fusion protein in onion cells or Arabidopsis protoplasts shows that AtNRAMP3 protein localizes to the vacuolar membrane. To account for the results presented, we propose that AtNRAMP3 influences metal accumulation and IRT1 and FRO2 gene expression by mobilizing vacuolar metal pools to the cytosol. PMID:12787249

  5. Transportation Planning with Immune System Derived Approach

    NASA Astrophysics Data System (ADS)

    Sugiyama, Kenji; Yaji, Yasuhito; Ootsuki, John Takuya; Fujimoto, Yasutaka; Sekiguchi, Takashi

    This paper presents an immune system derived approach for planning transportation of materials between manufacturing processes in the factory. Transportation operations are modeled by Petri Net, and divided into submodels. Transportation orders are derived from the firing sequences of those submodels through convergence calculation by the immune system derived excitation and suppression operations. Basic evaluation of this approach is conducted by simulation-based investigation.

  6. Low temperature charge transport and microwave absorption of carbon coated iron nanoparticles–polymer composite films

    SciTech Connect

    Prasad, V.

    2012-06-15

    Highlights: ► Carbon coated Fe nanoparticle–PVC composite films were prepared by solution casting method. ► A low electrical percolation threshold of 2.2 was achieved. ► The low temperature electrical conductivity follows variable range hopping type conduction. ► An EMI shielding of 18 dB was achieved in 200 micron thick film. -- Abstract: In this paper, the low temperature electrical conductivity and microwave absorption properties of carbon coated iron nanoparticles–polyvinyl chloride composite films are investigated for different filler fractions. The filler particles are prepared by the pyrolysis of ferrocene at 980 °C and embedded in polyvinyl chloride matrix. The high resolution transmission electron micrographs of the filler material have shown a 5 nm thin layer graphitic carbon covering over iron particles. The room temperature electrical conductivity of the composite film changes by 10 orders of magnitude with the increase of filler concentration. A percolation threshold of 2.2 and an electromagnetic interference shielding efficiency (EMI SE) of ∼18.6 dB in 26.5–40 GHz range are observed for 50 wt% loading. The charge transport follows three dimensional variable range hopping conduction.

  7. System for recycling char in iron oxide reducing kilns

    SciTech Connect

    Baker, A.C.; Keran, V.P.

    1983-03-08

    A method and means for improving the efficiency of the process for directly reducing ore containing iron oxide in a rotary kiln using a solid carbonaceous reducing agent, such as coal, introduced from the ore feed and discharge ends of the kiln, as both fuel and reductant, is disclosed wherein the charred coal or char found in the discharge product is recycled into the process at the discharge end of the kiln rather than the feed end as in the prior art. In particular, the recovered char, both coarse and finer particles, are transported to a recycle bin from which they are returned at a preselected rate to the kiln process by being injected along with the coal blown into the discharge end of the kiln. Alternatively, the recycle char alone may be fed without any coal at the discharge end of the kiln.

  8. Reduction of vinyl chloride in metallic iron-water systems

    SciTech Connect

    Deng, B. . Dept. of Mineral and Environmental Engineering); Burris, D.R. ); Campbell, T.J. )

    1999-08-01

    Batch experiments examining the kinetics and mechanism of vinyl chloride (VC) reduction by metallic iron in aqueous systems were performed. The effects of various iron loadings, VC concentrations, pH conditions, temperatures, and Fe(II)/Fe(III) chelating agents (1,10-phenanthroline, 2,2[prime]-dipyridyl, and nitrilotriacetic acid) on reduction kinetics were examined. Ethylene was the major carbon-containing product of VC reduction under all conditions examined, indicating hydrogenolysis. The reaction was pseudo-first-order with respect to aqueous VC concentration. The amount of VC adsorption on iron surfaces was estimated from the rapid initial loss of VC from solution, and the resultant sorption isotherm was linear over the concentration range examined. The first-order kinetics and the linear sorption for VC suggest that the portion of VC sorption to surface reactive sites relative to nonreactive sorption sites is constant, unlike the behavior observed for the higher chlorinated ethenes. The activation energy of the reaction was measured to be 41.6 [+-] 2.0 kJ/mol, sufficiently large to indicate that the chemical reaction at the surface, rather than aqueous phase diffusion to the surface, controls the overall rate of the reaction. Experiments with the chelating agents suggest that the effect of available Fe(II) on VC reduction is not significant.

  9. STARS: The Space Transportation Architecture Risk System

    NASA Technical Reports Server (NTRS)

    Greenberg, Joel S.

    1997-01-01

    Because of the need to perform comparisons between transportation systems that are likely to have significantly different levels of risk, both because of differing degrees of freedom in achieving desired performance levels and their different states of development and utilization, an approach has been developed for performing early comparisons of transportation architectures explicitly taking into account quantitative measures of uncertainty and resulting risk. The approach considers the uncertainty associated with the achievement of technology goals, the effect that the achieved level of technology will have on transportation system performance and the relationship between transportation system performance/capability and the ability to accommodate variations in payload mass. The consequences of system performance are developed in terms of expected values and associated standard deviations of nonrecurring, recurring and the present value of transportation system life cycle cost. Typical results are presented to illustrate the application of the methodology.

  10. Effect of Transport and Aging Processes on Metal Speciation in Iron Oxyhydroxide Aggregates, Tar Creek Superfund Site, Oklahoma

    NASA Astrophysics Data System (ADS)

    Estes, E. R.; Schaider, L. A.; Shine, J. P.; Brabander, D. J.

    2010-12-01

    Following the cessation of mining activity in the late 20th century, Tar Creek Superfund Site was left highly contaminated by Pb, Zn, and Cd. Tar Creek, which flows through the site and into the Neosho River, has been studied extensively because of its potential to transport metals from the mining site to downstream communities. Previous research identified aggregated iron oxyhydroxide material, which forms when mine seepage mixes with Tar Creek surface water, as a major transport vector of metals. Frequent flooding in Tar Creek deposits aggregates on downstream floodplains, where wetting and drying processes alter the speciation of iron and other metals. This study seeks to better quantify those changes and to determine how transport and aging affects the human and ecological health risk. Sequential extractions of aggregate samples collected from the creek demonstrate that Fe is present in both amorphous (10-35% of Fe extracted) and more crystalline (8-23% of Fe extracted) phases. Substantial portions of heavy metals sorb to amorphous iron oxyhydroxide phases (accounting for 10-30% of Pb and Zn extracted) but are not associated with more crystalline iron oxide phases (representing only 1% or less of the Pb and Zn extracted). Samples have a high organic matter content (18-25% mass loss on ignition), but only Fe was significantly extracted by the oxidizing step targeting organic matter (1-2% of Pb and Zn extracted, but 10-26% of Fe extracted). The majority of metals were extracted by the soluble or residual steps. If metals and organic matter inhibit transformation of amorphous iron oxyhydroxide material to nano and crystalline iron oxides, then a steady-state volume of amorphous iron oxyhydroxide material with a high total sorption capacity may exist within Tar Creek, enhancing the metal flux accommodated by this transport mechanism. Once transported downstream and deposited on floodplains, however, it is hypothesized that repeated changes in soil matrix