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Sample records for putative iron transporter

  1. A putative mitochondrial iron transporter MrsA in Aspergillus fumigatus plays important roles in azole-, oxidative stress responses and virulence

    Directory of Open Access Journals (Sweden)

    Nanbiao eLong

    2016-05-01

    Full Text Available Iron is an essential nutrient and enzyme co-factor required for a wide range of cellular processes, especially for the function of mitochondria. For the opportunistic fungal pathogen Aspergillus fumigatus, the ability to obtain iron is required for growth and virulence during the infection process. However, knowledge of how mitochondria are involved in iron regulation is still limited. Here, we show that a mitochondrial iron transporter, MrsA, a homolog of yeast Mrs4p, is critical for adaptation to iron-limited or iron-excess conditions in A. fumigatus. Deletion of mrsA leads to disruption of iron homeostasis with a decreased sreA expression, resulted in activated reductive iron assimilation (RIA and siderophore-mediated iron acquisition (SIA. Furthermore, deletion of mrsA induces hypersusceptibility to azole and oxidative stresses. An assay for cellular ROS content in ΔmrsA combined with rescue from the mrsA-defective phenotype by the antioxidant reagent L-ascorbic acid indicates that the increased sensitivity of ΔmrsA to the azole itraconazole and to oxidative stress is mainly the result of abnormal ROS accumulation. Moreover, site-directed mutation experiments verified that three conserved histidine residues related to iron transport in MrsA are required for responses to oxidative and azole stresses. Importantly, ΔmrsA causes significant attenuation of virulence in an immunocompromised murine model of aspergillosis. Collectively, our results show that the putative mitochondrial iron transporter MrsA plays important roles in azole- and oxidative-stress responses and virulence by regulating the balance of cellular iron in A. fumigatus.

  2. A Putative Mitochondrial Iron Transporter MrsA in Aspergillus fumigatus Plays Important Roles in Azole-, Oxidative Stress Responses and Virulence.

    Science.gov (United States)

    Long, Nanbiao; Xu, Xiaoling; Qian, Hui; Zhang, Shizhu; Lu, Ling

    2016-01-01

    Iron is an essential nutrient and enzyme co-factor required for a wide range of cellular processes, especially for the function of mitochondria. For the opportunistic fungal pathogen Aspergillus fumigatus, the ability to obtain iron is required for growth and virulence during the infection process. However, knowledge of how mitochondria are involved in iron regulation is still limited. Here, we show that a mitochondrial iron transporter, MrsA, a homolog of yeast Mrs4p, is critical for adaptation to iron-limited or iron-excess conditions in A. fumigatus. Deletion of mrsA leads to disruption of iron homeostasis with a decreased sreA expression, resulted in activated reductive iron assimilation (RIA) and siderophore-mediated iron acquisition (SIA). Furthermore, deletion of mrsA induces hypersusceptibility to azole and oxidative stresses. An assay for cellular ROS content in ΔmrsA combined with rescue from the mrsA-defective phenotype by the antioxidant reagent L-ascorbic acid indicates that the increased sensitivity of ΔmrsA to the azole itraconazole and to oxidative stress is mainly the result of abnormal ROS accumulation. Moreover, site-directed mutation experiments verified that three conserved histidine residues related to iron transport in MrsA are required for responses to oxidative and azole stresses. Importantly, ΔmrsA causes significant attenuation of virulence in an immunocompromised murine model of aspergillosis. Collectively, our results show that the putative mitochondrial iron transporter MrsA plays important roles in azole- and oxidative-stress responses and virulence by regulating the balance of cellular iron in A. fumigatus.

  3. Liver iron transport

    Institute of Scientific and Technical Information of China (English)

    Ross M Graham; Anita CG Chua; Carly E Herbison; John K Olynyk; Debbie Trinder

    2007-01-01

    The liver plays a central role in iron metabolism. It is the major storage site for iron and also expresses a complex range of molecules which are involved in iron transport and regulation of iron homeostasis. An increasing number of genes associated with hepatic iron transport or regulation have been identified. These include transferrin receptors (TFR1 and 2), a ferrireductase (STEAP3), the transporters divalent metal transporter-1 (DMT1) and ferroportin (FPN) as well as the haemochromatosis protein, HFE and haemojuvelin (HJV),which are signalling molecules. Many of these genes also participate in iron regulatory pathways which focus on the hepatic peptide hepcidin. However, we are still only beginning to understand the complex interactions between liver iron transport and iron homeostasis. This review outlines our current knowledge of molecules of iron metabolism and their roles in iron transport and regulation of iron homeostasis.

  4. Cellular iron transport.

    Science.gov (United States)

    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.

  5. Evaluating the function of putative hormone transporters.

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    Frommer, Wolf B; Schulz, Burkhard; Murphy, Angus S

    2009-02-01

    Hormones typically serve as long distance signaling molecules. To reach their site of action, hormones need to be transported from the sites of synthesis. Many plant hormones are mobile, thus requiring specific transport systems for the export from their source cells as well as subsequent import into target cells. Hormone transport in general is still poorly understood. Auxin is probably the most intensively studied plant hormone concerning transport in the moment. To advance our understanding of hormone transport we need two principal data sets: information on the properties of the transport systems including substrate specificity and kinetics, and we need to identify candidate genes for the respective transporters. Physiological transport data can provide an important basis for identifying and characterizing candidate transporters and to define their in vivo role. A recent publication in Plant Physiology highlights how kinetic and specificity studies may help to identify cytokinin transporters.

  6. Genetic defects of iron transport.

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    Bannerman, R M

    1976-09-01

    Five genetic traits in man and laboratory animals have major effects on iron transport. The heterogeneous condition, hemochromatosis, in some families appears to segregate as a Mendelian trait, and is associated with defective control of intestinal iron absorption. In the very rare human autosomal recessive trait, atransferrinemia, there is an almost total lack of transferrin and gross maldistribution of iron through the body. In mice, sex-linked anemia (an X-linked recessive trait) causes iron deficiency through defective iron absorption, at the "exit" step; a similar defect probably exists in placental iron transfer. In microcytic anemia of mice, an autosomal recessive trait, iron absorption is also impaired because of a defect of iron entry into cells, which is probably generalized. Belgrade rat anemia, less understood at present, also may involve a major disorder of iron metabolism. Study of these mutations has provided new knowledge of iron metabolism and its genetic control Their phenotypic interaction with nutritional factors, especially the form and quantity of iron in the diet, may provide new insights for the study of nutrition.

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

    Science.gov (United States)

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

    2011-08-09

    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.

  8. Ferrous iron transport in Streptococcus mutans

    Energy Technology Data Exchange (ETDEWEB)

    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.

  9. Iron transportation across the placenta

    Directory of Open Access Journals (Sweden)

    Claudia M. de Oliveira

    2012-12-01

    Full Text Available According to the classification of placental types among animals, the transfer of iron through the placenta can occur via: absorption connected to transferin through the outer surface of the trophoblast in direct contact with circulating maternal blood; absorption of the erythrocytes by the chorionic epithelium in direct contact with accumulation of blood extravased from haemotophagous areas; absorption by the chorionic epithelium in direct contact with iron enriched secretions from the endometrial glands and absorption by extravasations of the blood in the maternal-fetal surface and the subsequent phagocytosis of the erythrocytes by trophoblast cells described in bovine, small ruminants, canine and feline. The function of erythrophagocytosis observed after the extravasation of blood in the maternal-fetal interface is undefined in several species. Possibly, the iron is transferred to the fetus through the trophoblastic erythrophagocytosis in the hemophogous area of the placenta and also in the endometrial glands. In this literature survey, new methods of studies regarding placental transfer involving iron and other nutrients necessary for survival and maintenance of embryonic fetus to birth are proposed.De acordo com a classificação dos tipos de placenta existentes entre os animais e em relação com a passagem de substâncias pela barreira inter-hemática, a transferência de ferro pode ser realizada através da: absorção de ferro ligado a transferrina através da superfície externa do trofoblasto em contato direto com o sangue materno circulante; absorção de eritrócitos pelo epitélio coriônico em contato direto com acúmulos de sangue materno extravasado em áreas hematófagas, absorção de ferro pelo epitélio coriônico em contato direto com secreções ricas em ferro provenientes de glândulas endometriais e fagocitose dos eritrócitos pelas células trofoblásticas, a qual foi descrita em bovinos, pequenos ruminantes, caninos e

  10. Bacterial ferrous iron transport: the Feo system.

    Science.gov (United States)

    Lau, Cheryl K Y; Krewulak, Karla D; Vogel, Hans J

    2016-03-01

    To maintain iron homeostasis within the cell, bacteria have evolved various types of iron acquisition systems. Ferric iron (Fe(3+)) is the dominant species in an oxygenated environment, while ferrous iron (Fe(2+)) is more abundant under anaerobic conditions or at low pH. For organisms that must combat oxygen limitation for their everyday survival, pathways for the uptake of ferrous iron are essential. Several bacterial ferrous iron transport systems have been described; however, only the Feo system appears to be widely distributed and is exclusively dedicated to the transport of iron. In recent years, many studies have explored the role of the FeoB and FeoA proteins in ferrous iron transport and their contribution toward bacterial virulence. The three-dimensional structures for the Feo proteins have recently been determined and provide insight into the molecular details of the transport system. A highly select group of bacteria also express the FeoC protein from the same operon. This review will provide a comprehensive look at the structural and functional aspects of the Feo system. In addition, bioinformatics analyses of the feo operon and the Feo proteins have been performed to complement our understanding of this ubiquitous bacterial uptake system, providing a new outlook for future studies. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  11. AmcA - a putative mitochondrial ornithine transporter supporting fungal siderophore biosynthesis

    Directory of Open Access Journals (Sweden)

    Lukas eSchafferer

    2015-04-01

    Full Text Available Iron is an essential nutrient required for a wide range of cellular processes. The opportunistic fungal pathogen Aspergillus fumigatus employs low-molecular mass iron-specific chelators, termed siderophores, for uptake, storage and intracellular iron distribution, which play a crucial role in the pathogenicity of this fungus. Siderophore biosynthesis depends on coordination with the supply of its precursor ornithine, produced mitochondrially from glutamate or cytosolically via hydrolysis of arginine. In this study, we demonstrate a role of the putative mitochondrial transporter AmcA (AFUA_8G02760 in siderophore biosynthesis of A. fumigatus.Consistent with a role in cellular ornithine handling, AmcA-deficiency resulted in decreased cellular ornithine and arginine contents as well as decreased siderophore production on medium containing glutamine as the sole nitrogen source. In support, arginine and ornithine as nitrogen sources did not impact siderophore biosynthesis due to cytosolic ornithine availability. As revealed by Northern blot analysis, transcript levels of siderophore biosynthetic genes were unresponsive to the cellular ornithine level. In contrast to siderophore production, AmcA deficiency did only mildly decrease the cellular polyamine content, demonstrating cellular prioritization of ornithine use. Nevertheless, AmcA-deficiency increased the susceptibility of A. fumigatus to the polyamine biosynthesis inhibitor eflornithine, most likely due to the decreased ornithine pool. AmcA-deficiency decreased the growth rate particularly on ornithine as the sole nitrogen source during iron starvation and sufficiency, indicating an additional role in the metabolism and fitness of A. fumigatus, possibly in mitochondrial ornithine import. In the Galleria mellonella infection model, AmcA-deficiency did not affect virulence of A. fumigatus, most likely due to the residual siderophore production and arginine availability in this host niche.

  12. Hepcidin Suppresses Brain Iron Accumulation by Downregulating Iron Transport Proteins in Iron-Overloaded Rats.

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    Du, Fang; Qian, Zhong-Ming; Luo, Qianqian; Yung, Wing-Ho; Ke, Ya

    2015-08-01

    Iron accumulates progressively in the brain with age, and iron-induced oxidative stress has been considered as one of the initial causes for Alzheimer's disease (AD) and Parkinson's disease (PD). Based on the role of hepcidin in peripheral organs and its expression in the brain, we hypothesized that this peptide has a role to reduce iron in the brain and hence has the potential to prevent or delay brain iron accumulation in iron-associated neurodegenerative disorders. Here, we investigated the effects of hepcidin expression adenovirus (ad-hepcidin) and hepcidin peptide on brain iron contents, iron transport across the brain-blood barrier, iron uptake and release, and also the expression of transferrin receptor-1 (TfR1), divalent metal transporter 1 (DMT1), and ferroportin 1 (Fpn1) in cultured microvascular endothelial cells and neurons. We demonstrated that hepcidin significantly reduced brain iron in iron-overloaded rats and suppressed transport of transferrin-bound iron (Tf-Fe) from the periphery into the brain. Also, the peptide significantly inhibited expression of TfR1, DMT1, and Fpn1 as well as reduced Tf-Fe and non-transferrin-bound iron uptake and iron release in cultured microvascular endothelial cells and neurons, while downregulation of hepcidin with hepcidin siRNA retrovirus generated opposite results. We concluded that, under iron-overload, hepcidin functions to reduce iron in the brain by downregulating iron transport proteins. Upregulation of brain hepcidin by ad-hepcidin emerges as a new pharmacological treatment and prevention for iron-associated neurodegenerative disorders.

  13. Analysis of high iron rice lines reveals new miRNAs that target iron transporters in roots

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    Paul, Soumitra; Gayen, Dipak; Datta, Swapan K.; Datta, Karabi

    2016-01-01

    The present study highlights the molecular regulation of iron transport in soyFER1-overexpressing transgenic rice. Accumulation of iron in three different seed developmental stages, milk, dough, and mature, has been examined. The transgenic seeds of the milk stage showed significant augmentation of iron and zinc levels compared with wild-type seeds, and similar results were observed throughout the dough and mature stages. To investigate the regulation of iron transport, the role of miRNAs was studied in roots of transgenic rice. Sequencing of small RNA libraries revealed 153 known and 41 novel miRNAs in roots. Among them, 59 known and 14 novel miRNAs were found to be significantly expressed. miR166, miR399, and miR408 were identified as playing a vital role in iron uptake in roots of transgenic plants . Most importantly, four putative novel miRNAs, namely miR11, miR26, miR30, and miR31, were found to be down-regulated in roots of transgenic plants. For all these four novel miRNAs, natural resistance-associated macrophage protein 4 (NRAMP4), encoding a metal transporter, was predicted as a target gene. It is hypothesized that the NRAMP4 transporter is activated in roots of transgenic plants due to the lower abundance of its corresponding putative novel miRNAs. The relative transcript level of the NRAMP4 transcript was increased from 0.107 in the wild type to 65.24 and 55.39 in transgenic plants, which demonstrates the elevated amount of iron transport in transgenic plants. In addition, up-regulation of OsYSL15, OsFRO2, and OsIRT1 in roots also facilitates iron loading in transgenic seeds. PMID:27729476

  14. Transporters Contributing to Iron Trafficking in Plants

    Institute of Scientific and Technical Information of China (English)

    Sarah S. Conte; Elsbeth L. Walker

    2011-01-01

    T This review will discuss recent progress in understanding the many roles of transporters in the whole-plant physiological processes that maintain iron (Fe) homeostasis. These processes include uptake from the soil via roots, control of transport from roots to above-ground parts of the plant, unloading of Fe from the xylem in above-ground parts, loading of Fe into mitochondria and plastids, transport of Fe to reproductive parts of the plant, and Fe mobilization during seed germination. In addition, we will discuss the mechanisms that plants use to cope with an apparently unintended consequence of Fe acquisition: the uptake of toxic heavy metals via Fe transporters. Rapid progress has been made in understanding the transport processes involved in each of these areas in the last 5 years and this review will focus on this recent progress. We will also highlight the key questions regarding transport steps that remain to be elucidated.

  15. Coordination Chemistry of Microbial Iron Transport.

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

    2015-09-15

    This Account focuses on the coordination chemistry of the microbial iron chelators called siderophores. The initial research (early 1970s) focused on simple analogs of siderophores, which included hydroxamate, catecholate, or hydroxycarboxylate ligands. The subsequent work increasingly focused on the transport of siderophores and their microbial iron transport. Since these are pseudo-octahedral complexes often composed of bidentate ligands, there is chirality at the metal center that in principle is independent of the ligand chirality. It has been shown in many cases that chiral recognition of the complex occurs. Many techniques have been used to elucidate the iron uptake processes in both Gram-positive (single membrane) and Gram-negative (double membrane) bacteria. These have included the use of radioactive labels (of ligand, metal, or both), kinetically inert metal complexes, and Mössbauer spectroscopy. In general, siderophore recognition and transport involves receptors that recognize the metal chelate portion of the iron-siderophore complex. A second, to date less commonly found, mechanism called the siderophore shuttle involves the receptor binding an apo-siderophore. Since one of the primary ways that microbes compete with each other for iron stores is the strength of their competing siderophore complexes, it became important early on to characterize the solution thermodynamics of these species. Since the acidity of siderophores varies significantly, just the stability constant does not give a direct measure of the relative competitive strength of binding. For this reason, the pM value is compared. The pM, like pH, is a measure of the negative log of the free metal ion concentration, typically calculated at pH 7.4, and standard total concentrations of metal and ligand. The characterization of the electronic structure of ferric siderophores has done much to help explain the high stability of these complexes. A new chapter in siderophore science has emerged

  16. Dioxygen activation by a non-heme iron(II) complex: formation of an iron(IV)-oxo complex via C-H activation by a putative iron(III)-superoxo species.

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    Lee, Yong-Min; Hong, Seungwoo; Morimoto, Yuma; Shin, Woonsup; Fukuzumi, Shunichi; Nam, Wonwoo

    2010-08-11

    Iron(III)-superoxo intermediates are believed to play key roles in oxygenation reactions by non-heme iron enzymes. We now report that a non-heme iron(II) complex activates O(2) and generates its corresponding iron(IV)-oxo complex in the presence of substrates with weak C-H bonds (e.g., olefins and alkylaromatic compounds). We propose that a putative iron(III)-superoxo intermediate initiates the O(2)-activation chemistry by abstracting a H atom from the substrate, with subsequent generation of a high-valent iron(IV)-oxo intermediate from the resulting iron(III)-hydroperoxo species.

  17. Iron uptake and transport at the blood-brain barrier

    DEFF Research Database (Denmark)

    Larsen, Annette Burkhart; Thomsen, Louiza Bohn; Moos, Torben

    The mechanism by which iron is transported across the blood-brain barrier (BBB) remains controversial, and in this study we aimed to further clarify mechanisms by which iron is transported into the brain. We analyzed and compared the mRNA and protein expression of a variety of proteins involved i...... of hepcidin on iron efflux would indicate that ferroportin plays a role for iron efflux of ferrous non-transferrin bound iron at the BBB. Collectively, our data indicate that both routes are significant for transport of iron through the BBB initiated by receptor-mediated uptake of holo......-transferrin at the luminal side of brain capillaries and cellular entry in endosomes followed by: i) Transcytosis of holo-transferrin containing iron, and ii) Stepwise transport of iron through the endothelial cells from the endosomes via ferric reduction by Steap 2 and 3, transport of ferrous iron through the endosomal...... membrane to the cytosol mediated by DMT1, transport of ferrous iron through the abluminal endothelial cell membrane by ferroportin, and oxidation by the ferrooxidases ceruloplasmin and hephaestin. The two mechanisms for transport of iron at the BBB both explain how iron can enter the brain extracellular...

  18. Monoubiquitin-dependent endocytosis of the IRON-REGULATED TRANSPORTER 1 (IRT1) transporter controls iron uptake in plants

    OpenAIRE

    Barberon, Marie; Zelazny, Enric; Robert, Stéphanie; Conejero, Geneviève; Curie, Catherine; Friml, Jìrí; Vert, Grégory

    2011-01-01

    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 endosom...

  19. SO2907, A Putative TonB-dependent Receptor, Is Involved in Dissimilatory Iron Reduction by Shewanella oneidensis Strain MR-1

    Energy Technology Data Exchange (ETDEWEB)

    Qian, Yufeng; Shi, Liang; Tien, Ming

    2011-09-30

    Shewanella oneidensis strain MR-1 utilizes soluble and insoluble ferric ions as terminal electron acceptors during anaerobic respiration. The components of respiratory metabolism are localized in the membrane fractions which include the outer membrane and cytoplasmic membrane. Many of the biological components that interact with the various iron forms are proposed to be localized in these membrane fractions. To identify the iron-binding proteins acting either as an iron transporter or as a terminal iron reductase, we used metal-catalyzed oxidation reactions. This system catalyzed the oxidation of amino acids in close proximity to the iron binding site. The carbonyl groups formed from this oxidation can then be labeled with fluoresceinamine (FLNH2). The peptide harboring the FLNH2 can then be proteolytically digested, purified by HPLC and then identified by MALDI-TOF tandem MS. A predominant peptide was identified to be part of SO2907 that encodes a putative TonB-dependent receptor. Compared to wild type (wt), the so2097 gene deletion (ΔSO2907) mutant has impaired ability to reduce soluble Fe(III), but retains the same ability to respire oxygen or fumarate as the wt. The ΔSO2907 mutant was also impacted in reduction of insoluble iron. Iron binding assays using isothermal titration calorimetry and fluorescence tryptophan quenching demonstrated that a truncated form of heterologous-expressed SO2907 that contains the Fe(III) binding site, is capable of binding soluble Fe(III) forms with Kd of approximate 50 μM. To the best of our knowledge, this is the first report of the physiological role of SO2907 in Fe(III) reduction by MR-1.

  20. Vibrio Iron Transport: Evolutionary Adaptation to Life in Multiple Environments.

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    Payne, Shelley M; Mey, Alexandra R; Wyckoff, Elizabeth E

    2016-03-01

    Iron is an essential element for Vibrio spp., but the acquisition of iron is complicated by its tendency to form insoluble ferric complexes in nature and its association with high-affinity iron-binding proteins in the host. Vibrios occupy a variety of different niches, and each of these niches presents particular challenges for acquiring sufficient iron. Vibrio species have evolved a wide array of iron transport systems that allow the bacteria to compete for this essential element in each of its habitats. These systems include the secretion and uptake of high-affinity iron-binding compounds (siderophores) as well as transport systems for iron bound to host complexes. Transporters for ferric and ferrous iron not complexed to siderophores are also common to Vibrio species. Some of the genes encoding these systems show evidence of horizontal transmission, and the ability to acquire and incorporate additional iron transport systems may have allowed Vibrio species to more rapidly adapt to new environmental niches. While too little iron prevents growth of the bacteria, too much can be lethal. The appropriate balance is maintained in vibrios through complex regulatory networks involving transcriptional repressors and activators and small RNAs (sRNAs) that act posttranscriptionally. Examination of the number and variety of iron transport systems found in Vibrio spp. offers insights into how this group of bacteria has adapted to such a wide range of habitats.

  1. ZIPCO, a putative metal ion transporter, is crucial for Plasmodium liver-stage development.

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    Sahu, Tejram; Boisson, Bertrand; Lacroix, Céline; Bischoff, Emmanuel; Richier, Quentin; Formaglio, Pauline; Thiberge, Sabine; Dobrescu, Irina; Ménard, Robert; Baldacci, Patricia

    2014-11-01

    The malaria parasite, Plasmodium, requires iron for growth, but how it imports iron remains unknown. We characterize here a protein that belongs to the ZIP (Zrt-, Irt-like Protein) family of metal ion transport proteins and have named ZIP domain-containing protein (ZIPCO). Inactivation of the ZIPCO-encoding gene in Plasmodium berghei, while not affecting the parasite's ability to multiply in mouse blood and to infect mosquitoes, greatly impairs its capacity to develop inside hepatocytes. Iron/zinc supplementation and depletion experiments suggest that ZIPCO is required for parasite utilization of iron and possibly zinc, consistent with its predicted function as a metal transporter. This is the first report of a ZIP protein having a crucial role in Plasmodium liver-stage development, as well as the first metal ion transporter identified in Plasmodium pre-erythrocytic stages. Because of the drastic dependence on iron of Plasmodium growth, ZIPCO and related proteins might constitute attractive drug targets to fight against malaria. © 2014 Institut Pasteur. Published under the terms of the CC BY 4.0 license.

  2. A putative ABC transporter is involved in negative regulation of biofilm formation by Listeria monocytogenes

    DEFF Research Database (Denmark)

    Zhu, Xinna; Long, Fei; Chen, Yonghui

    2008-01-01

    Listeria monocytogenes may persist for long periods in food processing environments. In some instances, this may be due to aggregation or biofilm formation. To investigate the mechanism controlling biofilm formation in the food-borne pathogen L. monocytogenes, we characterized LM-49, a mutant...... with enhanced ability of biofilm-formation generated via transposon Tn917 mutagenesis of L. monocytogenes 4b G. In this mutant, a Tn917 insertion has disrupted the coding region of the gene encoding a putative ATP binding cassette (ABC) transporter permease identical to Lmof2365_1771 (a putative ABC......-transporter permease) presented in the sequenced strain L. monocytogenes str. 4b F2365. This disrupted gene, denoted lm.G_1771, encoded a protein with 10 transmembrane helixes. The revertant, LM-49RE, was obtained by replacing lm.G_1771::Tn917 with lm.G_1771 via homologous recombination. We found that LM-49RE formed...

  3. Characterization of a putative grapevine Zn transporter, VvZIP3, suggests its involvement in early reproductive development in Vitis vinifera L

    Science.gov (United States)

    2012-01-01

    Background Zinc (Zn) deficiency is one of the most widespread mineral nutritional problems that affect normal development in plants. Because Zn cannot passively diffuse across cell membranes, it must be transported into intracellular compartments for all biological processes where Zn is required. Several members of the Zinc-regulated transporters, Iron-regulated transporter-like Protein (ZIP) gene family have been characterized in plants, and have shown to be involved in metal uptake and transport. This study describes the first putative Zn transporter in grapevine. Unravelling its function may explain an important symptom of Zn deficiency in grapevines, which is the production of clusters with fewer and usually smaller berries than normal. Results We identified and characterized a putative Zn transporter from berries of Vitis vinifera L., named VvZIP3. Compared to other members of the ZIP family identified in the Vitis vinifera L. genome, VvZIP3 is mainly expressed in reproductive tissue - specifically in developing flowers - which correlates with the high Zn accumulation in these organs. Contrary to this, the low expression of VvZIP3 in parthenocarpic berries shows a relationship with the lower Zn accumulation in this tissue than in normal seeded berries where its expression is induced by Zn. The predicted protein sequence indicates strong similarity with several members of the ZIP family from Arabidopsis thaliana and other species. Moreover, VvZIP3 complemented the growth defect of a yeast Zn-uptake mutant, ZHY3, and is localized in the plasma membrane of plant cells, suggesting that VvZIP3 has the function of a Zn uptake transporter. Conclusions Our results suggest that VvZIP3 encodes a putative plasma membrane Zn transporter protein member of the ZIP gene family that might play a role in Zn uptake and distribution during the early reproductive development in Vitis vinifera L., indicating that the availability of this micronutrient may be relevant for

  4. Characterization of putative multidrug resistance transporters of the major facilitator-superfamily expressed in Salmonella Typhi.

    Science.gov (United States)

    Shaheen, Aqsa; Ismat, Fouzia; Iqbal, Mazhar; Haque, Abdul; De Zorzi, Rita; Mirza, Osman; Walz, Thomas; Rahman, Moazur

    2015-05-01

    Multidrug resistance mediated by efflux pumps is a well-known phenomenon in infectious bacteria. Although much work has been carried out to characterize multidrug efflux pumps in Gram-negative and Gram-positive bacteria, such information is still lacking for many deadly pathogens. The aim of this study was to gain insight into the substrate specificity of previously uncharacterized transporters of Salmonella Typhi to identify their role in the development of multidrug resistance. S. Typhi genes encoding putative members of the major facilitator superfamily were cloned and expressed in the drug-hypersensitive Escherichia coli strain KAM42, and tested for transport of 25 antibacterial compounds, including representative antibiotics of various classes, antiseptics, dyes and detergents. Of the 15 tested putative transporters, STY0901, STY2458 and STY4874 exhibited a drug-resistance phenotype. Among these, STY4874 conferred resistance to at least ten of the tested antimicrobials: ciprofloxacin, norfloxacin, levofloxacin, kanamycin, streptomycin, gentamycin, nalidixic acid, chloramphenicol, ethidium bromide, and acriflavine, including fluoroquinolone antibiotics, which were drugs of choice to treat S. Typhi infections. Cell-based functional studies using ethidium bromide and acriflavine showed that STY4874 functions as a H(+)-dependent exporter. These results suggest that STY4874 may be an important drug target, which can now be tested by studying the susceptibility of a STY4874-deficient S. Typhi strain to antimicrobials.

  5. A Synthetic Peptide with the Putative Iron Binding Motif of Amyloid Precursor Protein (APP) Does Not Catalytically Oxidize Iron

    NARCIS (Netherlands)

    Honarmand Ebrahimi, K.; Hagedoorn, P.L.; Hagen, W.R.

    2012-01-01

    The β-amyloid precursor protein (APP), which is a key player in Alzheimer's disease, was recently reported to possess an Fe(II) binding site within its E2 domain which exhibits ferroxidase activity [Duce et al. 2010, Cell 142: 857]. The putative ligands of this site were compared to those in the fer

  6. Molecular dissection of a putative iron reductase from Desulfotomaculum reducens MI-1.

    Science.gov (United States)

    Li, Zhi; Kim, David D; Nelson, Ornella D; Otwell, Anne E; Richardson, Ruth E; Callister, Stephen J; Lin, Hening

    2015-11-20

    Desulfotomaculum reducens MI-1 is a Firmicute strain capable of reducing a variety of heavy metal ions and has a great potential in heavy metal bioremediation. We recently identified Dred_2421 as a potential iron reductase through proteomic study of D. reducens. The current study examines its iron-reduction mechanism. Dred_2421, like its close homolog from Escherichia coli (2, 4-dienoyl-CoA reductase), has an FMN-binding N-terminal domain (NTD), an FAD-binding C-terminal domain (CTD), and a 4Fe-4S cluster between the two domains. To understand the mechanism of the iron-reduction activity and the role of each domain, we generated a series of variants for each domain and investigated their iron-reduction activity. Our results suggest that CTD is the main contributor of the iron-reduction activity, and that NTD and the 4Fe-4S cluster are not directly involved in such activity. This study provides a mechanistic understanding of the iron-reductase activity of Dred_2421 and may also help to elucidate other physiological activities this enzyme may have.

  7. Molecular dissection of a putative iron reductase from Desulfotomaculum reducens MI-1

    Science.gov (United States)

    Li, Zhi; Kim, David D.; Nelson, Ornella D.; Otwell, Anne E.; Richardson, Ruth E.; Callister, Stephen J.; Lin, Hening

    2015-01-01

    Desulfotomaculum reducens MI-1 is a Firmicute strain capable of reducing a variety of heavy metal ions and has a great potential in heavy metal bioremediation. We recently identified Dred_2421 as a potential iron reductase through proteomic study of D. reducens. The current study examines its iron-reduction mechanism. Dred_2421, like its close homolog from Escherichia coli (2, 4-dienoyl-CoA reductase), has an FMN-binding N-terminal domain (NTD), an FAD-binding C-terminal domain (CTD), and a 4Fe-4S cluster between the two domains. To understand the mechanism of the iron-reduction activity and the role of each domain, we generated a series of variants for each domain and investigated their iron-reduction activity. Our results suggest that CTD is the main contributor of the iron-reduction activity, and that NTD and the 4Fe-4S cluster are not directly involved in such activity. This study provides a mechanistic understanding of the iron-reductase activity of Dred_2421 and may also help to elucidate other physiological activities this enzyme may have. PMID:26454174

  8. A synthetic peptide with the putative iron binding motif of amyloid precursor protein (APP) does not catalytically oxidize iron.

    Science.gov (United States)

    Ebrahimi, Kourosh Honarmand; Hagedoorn, Peter-Leon; Hagen, Wilfred R

    2012-01-01

    The β-amyloid precursor protein (APP), which is a key player in Alzheimer's disease, was recently reported to possess an Fe(II) binding site within its E2 domain which exhibits ferroxidase activity [Duce et al. 2010, Cell 142: 857]. The putative ligands of this site were compared to those in the ferroxidase site of ferritin. The activity was indirectly measured using transferrin, which scavenges the Fe(III) product of the reaction. A 22-residue synthetic peptide, named FD1, with the putative ferroxidase site of APP, and the E2 domain of APP were each reported to exhibit 40% of the ferroxidase activity of APP and of ceruloplasmin. It was also claimed that the ferroxidase activity of APP is inhibited by Zn(II) just as in ferritin. We measured the ferroxidase activity indirectly (i) by the incorporation of the Fe(III) product of the ferroxidase reaction into transferrin and directly (ii) by monitoring consumption of the substrate molecular oxygen. The results with the FD1 peptide were compared to the established ferroxidase activities of human H-chain ferritin and of ceruloplasmin. For FD1 we observed no activity above the background of non-enzymatic Fe(II) oxidation by molecular oxygen. Zn(II) binds to transferrin and diminishes its Fe(III) incorporation capacity and rate but it does not specifically bind to a putative ferroxidase site of FD1. Based on these results, and on comparison of the putative ligands of the ferroxidase site of APP with those of ferritin, we conclude that the previously reported results for ferroxidase activity of FD1 and - by implication - of APP should be re-evaluated.

  9. A synthetic peptide with the putative iron binding motif of amyloid precursor protein (APP does not catalytically oxidize iron.

    Directory of Open Access Journals (Sweden)

    Kourosh Honarmand Ebrahimi

    Full Text Available The β-amyloid precursor protein (APP, which is a key player in Alzheimer's disease, was recently reported to possess an Fe(II binding site within its E2 domain which exhibits ferroxidase activity [Duce et al. 2010, Cell 142: 857]. The putative ligands of this site were compared to those in the ferroxidase site of ferritin. The activity was indirectly measured using transferrin, which scavenges the Fe(III product of the reaction. A 22-residue synthetic peptide, named FD1, with the putative ferroxidase site of APP, and the E2 domain of APP were each reported to exhibit 40% of the ferroxidase activity of APP and of ceruloplasmin. It was also claimed that the ferroxidase activity of APP is inhibited by Zn(II just as in ferritin. We measured the ferroxidase activity indirectly (i by the incorporation of the Fe(III product of the ferroxidase reaction into transferrin and directly (ii by monitoring consumption of the substrate molecular oxygen. The results with the FD1 peptide were compared to the established ferroxidase activities of human H-chain ferritin and of ceruloplasmin. For FD1 we observed no activity above the background of non-enzymatic Fe(II oxidation by molecular oxygen. Zn(II binds to transferrin and diminishes its Fe(III incorporation capacity and rate but it does not specifically bind to a putative ferroxidase site of FD1. Based on these results, and on comparison of the putative ligands of the ferroxidase site of APP with those of ferritin, we conclude that the previously reported results for ferroxidase activity of FD1 and - by implication - of APP should be re-evaluated.

  10. Vacuolar iron transporter BnMEB2 is involved in enhancing iron tolerance of Brassica napus

    Directory of Open Access Journals (Sweden)

    Wei Zhu

    2016-09-01

    Full Text Available Iron toxicity is a major nutrient disorder that severely affects crop development and yield. Vacuolar detoxification of metal stress is an important strategy for plants to survive and adapt to this adverse environment. Vacuolar iron transporter (VIT members are involved in this process and play essential roles in iron storage and transport. In this study, a rapeseed VIT gene BnMEB2 (BnaC07g30170D was identified. BnMEB2 is a homolog to Arabidopsis MEB2 (At5g24290 and acts as a detoxifier in vacuolar sequestration of divalent metal. Transient expression analysis revealed that BnMEB2 was localized to the vacuolar membrane. Q-PCR detection showed a high expression of BnMEB2 in mature (60-day-old leaves and could be obviously induced by exogenous iron stress in both roots and leaves. Over-expressed BnMEB2 in both Arabidopsis wild type and meb2 mutant seedlings resulted in greatly improved iron tolerability with no significant changes in the expression level of other vacuolar iron transporter genes. The mutant meb2 grew slowly and its root hair elongation was inhibited under high iron concentration condition while BnMEB2 over-expressed transgenic plants of the mutant restored the phenotypes with apparently higher iron storage in roots and dramatically increased iron content in the whole plant. Taken together, these results suggested that BnMEB2 was a VIT gene in rapeseed which was necessary for safe storage and vacuole detoxification function of excess iron to enhance the tolerance of iron toxicity. This research sheds light on a potentially new strategy for attenuating hazardous metal stress from environment and improving iron biofortification in Brassicaceae crops.

  11. Promoter activity of a putative pollen monosaccharide transporter in Petunia hybrida and characterisation of a transposon insertion mutant

    NARCIS (Netherlands)

    Garrido, D.; Busscher-Lange, J.; Tunen, van A.J.

    2006-01-01

    For the growth of the male reproductive cells of plants, the pollen, the presence of sufficient sucrose or monosaccharides is of vital importance. From Petunia hybrida a pollen-specific putative monosaccharide transporter designated PMT1 (for petunia monosaccharide transporter) has been identified p

  12. Hydrogen transport in iron and steel

    Science.gov (United States)

    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.

  13. Recognition of iron-free siderophores by TonB-dependent iron transporters.

    Science.gov (United States)

    Schalk, Isabelle J; Yue, Wyatt W; Buchanan, Susan K

    2004-10-01

    TonB-dependent iron transporters reside in the outer membranes of Gram-negative bacteria, transporting ferric-complexes into the periplasm by a mechanism requiring proton motive force and an integral inner membrane complex, TonB-ExbB-ExbD. Certain TonB-dependent transporters contain an additional domain at the N-terminus, which interacts with an inner membrane regulatory protein and a cytoplasmic sigma factor to induce transcription of iron transport genes when a ferric-ligand is bound at the extracellular surface of the transporter. Transport of the ferric-ligand is apparently not necessary for transcription induction. Recent biophysical and crystallographic experiments have shown that this subclass of TonB-dependent iron transporters can bind iron-free ligands, whereas only the ferric-ligands are transported into the periplasm. This review focuses on the ligand binding properties of these transporters and includes a discussion of the biological function of the additional domain, the mechanism of transcription induction and the mechanism of ferric-ligand transport.

  14. Molecular dissection of a putative iron reductase from Desulfotomaculum reducens MI-1

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zhi; Kim, David D.; Nelson, Ornella D.; Otwell, Annie E.; Richardson, Ruth E.; Callister, Stephen J.; Lin, Hening

    2015-10-08

    Desulfotomaculum reducens MI-1 is a Firmicute strain capable of reducing a variety of heavy metal ions and has a great potential in heavy metal bioremediation.We recently identified Dred_2421 as a potential iron reductase through proteomic study of D. reducens. The current study examines its iron-reduction mechanism. Dred_2421, like its close homolog from Escherichia coli (2, 4-dienoyl-CoA reductase), has an FMN-binding N-terminal domain (NTD), an FAD-binding C-terminal domain (CTD), and a 4Fee4S cluster between the two domains. To understand the mechanism of the iron-reduction activity and the role of each domain, we generated a series of variants for each domain and investigated their iron reduction activity. Our results suggest that CTD is the main contributor of the iron-reduction activity, and that NTD and the 4Fee4S cluster are not directly involved in such activity. This study provides a mechanistic understanding of the ironereductase activity of Dred_2421 and may also help to elucidate other physiological activities this enzyme may have.

  15. A study on iron ore transportation model with penalty value of transportation equipment waiting

    Directory of Open Access Journals (Sweden)

    Kailing Pan

    2017-03-01

    Full Text Available As some steel enterprises are at a disadvantage in the choice of the mode of transportation, this paper made further studies of the characteristics of the iron ore logistics, taking comprehensive consideration of optimizing the waiting time under the conditions with limited loading capacity and setting up a procedural model of the iron ore logistics system with minimum cost of transportation, storage, loading, unloading, and transportation equipment waiting. Finally, taking the iron ore transport system of one steel enterprise as example, the solution and the validity of the model were analyzed and verified in this paper.

  16. Vacuolar Iron Transporter BnMEB2 Is Involved in Enhancing Iron Tolerance of Brassica napus

    OpenAIRE

    Zhu, Wei; Zuo, Rong; Zhou, Rongfang; Huang, Junyan; Tang, Minqiang; Cheng, Xiaohui; Liu, Yueying; Tong, Chaobo; XIANG, YANG; Dong, Caihua; Liu, Shengyi

    2016-01-01

    Iron toxicity is a nutrient disorder that severely affects crop development and yield in some soil conditions. Vacuolar detoxification of metal stress is an important strategy for plants to survive and adapt to this adverse environment. Vacuolar iron transporter (VIT) members are involved in this process and play essential roles in iron storage and transport. In this study, we identified a rapeseed VIT gene BnMEB2 (BnaC07g30170D) homologs to Arabidopsis MEB2 (At5g24290). Transient expression ...

  17. Iron transport & homeostasis mechanisms: their role in health & disease.

    Science.gov (United States)

    Nadadur, S S; Srirama, K; Mudipalli, Anuradha

    2008-10-01

    Iron is an essential trace metal required by all living organisms and is toxic in excess. Nature has evolved a delicately balanced network to monitor iron entry, transport it to sites of need, and serve as a unique storage and recycling system, in the absence of an excretory system, to remove excess iron. Due to the unique nature of iron metabolism, iron homeostasis is achieved by integrated specialized mechanisms that operate at the cellular and organism level. The use of positional cloning approaches by multiple researchers has led to the identification and characterization of various proteins and peptides that play a critical role in iron metabolism. These efforts have led to elucidation of the molecular mechanisms involved in the uptake of iron by the enterocytes, transportation across the membrane to circulation, and delivery to diverse tissues for use and storage and sensor system to co-ordinate and achieve homeostasis. Molecular understanding of these processes and the key regulatory molecules involved in maintaining homeostasis will provide novel insights into understanding human disorders associated with either iron deficiency or overload.

  18. Characterization of the putative cholesterol transport protein metastatic lymph node 64 in the brain.

    Science.gov (United States)

    King, S R; Smith, A G A; Alpy, F; Tomasetto, C; Ginsberg, S D; Lamb, D J

    2006-01-01

    Intracellular management of cholesterol is a critical process in the brain. Deficits with cholesterol transport and storage are linked to neurodegenerative disorders such as Neimann-Pick disease type C and Alzheimer's disease. One protein putatively involved in cholesterol transport is metastatic lymph node 64 (MLN64). MLN64 localizes to late endosomes which are part of the cholesterol internalization pathway. However, a detailed pattern of MLN64 expression in the brain is unclear. Using immunocytochemical and immunoblot analyses, we demonstrated the presence of MLN64 in several tissue types and various regions within the brain. MLN64 immunostaining in the CNS was heterogeneous, indicating selective expression in discrete specific cell populations and regions. MLN64 immunoreactivity was detected in glia and neurons, which displayed intracellular labeling consistent with an endosomal localization. Although previous studies suggested that MLN64 may promote steroid production in the brain, MLN64 immunoreactivity did not colocalize with steroidogenic cells in the CNS. These results demonstrate that MLN64 is produced in the mouse and human CNS in a restricted pattern of expression, suggesting that MLN64 serves a cell-specific function in cholesterol transport.

  19. Exploiting nanotechnologies and TRPV1 channels to investigate the putative anandamide membrane transporter.

    Directory of Open Access Journals (Sweden)

    Alessia Ligresti

    Full Text Available BACKGROUND: Considerable efforts have been made to characterize the pathways regulating the extracellular levels of the endocannabinoid anandamide. However, none of such pathways has been so argued as the existence of a carrier-mediated transport of anandamide across the membrane. Apart from the lack of molecular evidence for such a carrier, the main reasons of this controversy lie in the methodologies currently used to study anandamide cellular uptake. Furthermore, the main evidence in favor of the existence of an "anandamide transporter" relies on synthetic inhibitors of this process, the selectivity of which has been questioned. METHODOLOGY/PRINCIPAL FINDINGS: We used the cytosolic binding site for anandamide on TRPV1 channels as a biosensor to detect anandamide entry into cells, and exploited nanotechnologies to study anandamide membrane transport into intact TRPV1-overexpressing HEK-293 cells. Both fluorescence and digital holographic (DH quantitative phase microscopy were used to study TRPV1 activation. Poly-epsilon-caprolactone nanoparticles (PCL-NPs were used to incorporate anandamide, which could thus enter the cell and activate TRPV1 channels bypassing any possible specific protein(s involved in the uptake process. We reasoned that in the absence of such protein(s, pharmacological tools previously shown to inhibit the "anandamide transporter" would affect in the same way the uptake of anandamide and PCL-NP-anandamide, and hence the activation of TRPV1. However, when masked into PCL-NPs, anandamide cellular uptake became much less sensitive to these agents, although it maintained the same pharmacokinetics and pharmacodynamics as that of "free" anandamide. CONCLUSIONS: We found here that several agents previously reported to inhibit anandamide cellular uptake lose their efficacy when anandamide is prevented from interacting directly with plasma membrane proteins, thus arguing in favor of the specificity of such agents for the putative

  20. Pyrosequencing of the Camptotheca acuminata transcriptome reveals putative genes involved in camptothecin biosynthesis and transport

    Directory of Open Access Journals (Sweden)

    Sun Yongzhen

    2011-10-01

    Full Text Available Abstract Background Camptotheca acuminata is a Nyssaceae plant, often called the "happy tree", which is indigenous in Southern China. C. acuminata produces the terpenoid indole alkaloid, camptothecin (CPT, which exhibits clinical effects in various cancer treatments. Despite its importance, little is known about the transcriptome of C. acuminata and the mechanism of CPT biosynthesis, as only few nucleotide sequences are included in the GenBank database. Results From a constructed cDNA library of young C. acuminata leaves, a total of 30,358 unigenes, with an average length of 403 bp, were obtained after assembly of 74,858 high quality reads using GS De Novo assembler software. Through functional annotation, a total of 21,213 unigenes were annotated at least once against the NCBI nucleotide (Nt, non-redundant protein (Nr, Uniprot/SwissProt, Kyoto Encyclopedia of Genes and Genomes (KEGG, and Arabidopsis thaliana proteome (TAIR databases. Further analysis identified 521 ESTs representing 20 enzyme genes that are involved in the backbone of the CPT biosynthetic pathway in the library. Three putative genes in the upstream pathway, including genes for geraniol-10-hydroxylase (CaPG10H, secologanin synthase (CaPSCS, and strictosidine synthase (CaPSTR were cloned and analyzed. The expression level of the three genes was also detected using qRT-PCR in C. acuminata. With respect to the branch pathway of CPT synthesis, six cytochrome P450s transcripts were selected as candidate transcripts by detection of transcript expression in different tissues using qRT-PCR. In addition, one glucosidase gene was identified that might participate in CPT biosynthesis. For CPT transport, three of 21 transcripts for multidrug resistance protein (MDR transporters were also screened from the dataset by their annotation result and gene expression analysis. Conclusion This study produced a large amount of transcriptome data from C. acuminata by 454 pyrosequencing. According to

  1. Geochemical investigation of iron transport into bentonite as steel corrodes

    Energy Technology Data Exchange (ETDEWEB)

    Hunter, Fiona; Bate, Fiona; Heath, Tim; Hoch, Andrew [Serco Assurance, Harwe ll (United Kingdom)

    2007-09-15

    some experiments. Using the experimental data as a guide, a modelling investigation has been carried out. The objectives of the modelling investigation were: To develop a geochemical model of the transport of iron into bentonite based on the clear experimental evidence of the penetration of iron into bentonite. To improve our understanding of the desaturation of the bentonite as water is consumed during the corrosion process and the resultant gas(es) escapes. The production of iron from the corroding source was modelled using a rate of gas evolution that had been fitted. It was shown that ion exchange and surface complexation processes do not provide sufficient sorption to predict the high amount of iron observed in the solid phase. Therefore alternative processes, such as iron-containing mineral formation or mineral transformations, were also suggested to account for the amount of iron observed within the bentonite phase. Magnetite was identified as the most thermodynamically stable solubility limiting phase under the experimental conditions. A one-dimensional transport model was constructed to include all relevant processes. The simulations considered the diffusive transport of Fe{sup 2+} ions away from a corroding source, using the rate of gas evolution resulting from the corrosion process. Ion exchange and surface complexation processes were allowed within the bentonite which would provide sorption of iron onto and within the bentonite solid. The pH was buffered by allowing protonation and deprotonation of the surface sites of the bentonite solid. In addition, saturation of iron-containing minerals was permitted. The base case model suggests that about 4.4 wt % of iron could form in the bentonite if the formation of magnetite was allowed. However, the maximum theoretical amount of iron available from the source term is limited to 4.5 wt % of iron by the cumulative gas evolution rate, which is lower than the observed amount of iron in the bulk bentonite (6.6 wt

  2. Demonstration of the heterolytic O-O bond cleavage of putative nonheme iron(II)-OOH(R) complexes for Fenton and enzymatic reactions.

    Science.gov (United States)

    Bang, Suhee; Park, Sora; Lee, Yong-Min; Hong, Seungwoo; Cho, Kyung-Bin; Nam, Wonwoo

    2014-07-21

    One-electron reduction of mononuclear nonheme iron(III) hydroperoxo (Fe(III)-OOH) and iron(III) alkylperoxo (Fe(III)-OOR) complexes by ferrocene (Fc) derivatives resulted in the formation of the corresponding iron(IV) oxo complexes. The conversion rates were dependent on the concentration and oxidation potentials of the electron donors, thus indicating that the reduction of the iron(III) (hydro/alkyl)peroxo complexes to their one-electron reduced iron(II) (hydro/alkyl)peroxo species is the rate-determining step, followed by the heterolytic O-O bond cleavage of the putative iron(II) (hydro/alkyl)peroxo species to give the iron(IV) oxo complexes. Product analysis supported the heterolytic O-O bond-cleavage mechanism. The present results provide the first example showing the one-electron reduction of iron(III) (hydro/alkyl)peroxo complexes and the heterolytic O-O bond cleavage of iron(II) (hydro/alkyl)peroxo species to form iron(IV) oxo intermediates which occur in nonheme iron enzymatic and Fenton reactions.

  3. Functional analysis of putative phosphoenolpyruvate transporters localized to the Golgi apparatus in Schizosaccharomyces pombe.

    Science.gov (United States)

    Yoritsune, Ken-ichi; Higuchi, Yujiro; Matsuzawa, Tomohiko; Takegawa, Kaoru

    2014-11-01

    The cell surface of Schizosaccharomyces pombe is negatively charged due to the presence of pyruvylated oligosaccharides, which is important for cell-cell recognition. However, the mechanism of pyruvate supply to oligosaccharides is not clearly understood. Here, we analyzed three putative phosphoenolpyruvate (PEP) transporter genes (pet1(+) , pet2(+) , and pet3(+) ) in S. pombe, identified by sequence homology search against the Arabidopsis thaliana PEP transporter AtPPT1. Schizosaccharomyces pombe strain carrying a disruption in pet1(+) (pet1Δ) or in pet2(+) (pet2Δ), but not the strain carrying a disruption in pet3(+) (pet3Δ), showed reduced pyruvate level on the cell surface. This reduction in pyruvate level was restored to the control level by expressing green fluorescent protein (GFP)-tagged Pet1p and Pet2p in respective disruptants. Fluorescence microscope studies revealed that GFP-tagged Pet1p and Pet2p were localized to the Golgi apparatus. Although expression of neither AtPPT1 nor AtPPT2 suppressed the pet1Δ phenotype, that of chimeric constructs, where the N-terminal regions of AtPPT1 and AtPPT2 were replaced by the N-terminal region of Pet1p, partially suppressed the pet1Δ phenotype. Furthermore, the reduction in cell surface negative charge in pet1Δ cells was restored by incubating these cells with recombinant Pvg1p and PEP. Thus, Pet1p and Pet2p are likely involved in transporting PEP from the cytoplasm into the Golgi.

  4. Functional Characterization of a Putative Nitrate Transporter Gene Promoter from Rice

    Institute of Scientific and Technical Information of China (English)

    Ting-Zhang HU; Kai-Ming CAO; Mian XIA; Xi-Ping WANG

    2006-01-01

    Drought is one of the most significant abiotic stresses that influence plant growth and development. Expression analysis revealed that OsNRT1.3, a putative nitrate transporter gene in rice, was induced by drought. To confirm if the OsNRT1.3 promoter can respond to drought stress, a 2019 bp upstream sequence of OsNRT1.3 was cloned. Three OsNRT1.3 promoter fragments were generated by 5'-deletion, and fused to the β-glucuronidase (GUS) gene. The chimeric genes were introduced into rice plants. NRT2019::GUS, NRT1196: :GUS and NRT719::GUS showed similar expression patterns in seeds,roots, leaves and flowers in all transgenic rice, and GUS activity conferred by different OsNRT1.3 promoter fragments was significantly upregulated by drought stress, indicating that OsNRT1.3 promoter responds to drought stress and the 719 bp upstream sequence of OsNRT1.3 contains the drought response elements.

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

    Directory of Open Access Journals (Sweden)

    Yoshiko Murata

    Full Text Available 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

  6. Characterization of ferric and ferrous iron transport systems in Vibrio cholerae.

    Science.gov (United States)

    Wyckoff, Elizabeth E; Mey, Alexandra R; Leimbach, Andreas; Fisher, Carolyn F; Payne, Shelley M

    2006-09-01

    Vibrio cholerae has multiple iron acquisition systems, including TonB-dependent transport of heme and of the catechol siderophore vibriobactin. Strains defective in both of these systems grow well in laboratory media and in the infant mouse intestine, indicating the presence of additional iron acquisition systems. Previously uncharacterized potential iron transport systems, including a homologue of the ferrous transporter Feo and a periplasmic binding protein-dependent ATP binding cassette (ABC) transport system, termed Fbp, were identified in the V. cholerae genome sequence. Clones encoding either the Feo or the Fbp system exhibited characteristics of iron transporters: both repressed the expression of lacZ cloned under the control of a Fur-regulated promoter in Escherichia coli and also conferred growth on a Shigella flexneri mutant that has a severe defect in iron transport. Two other ABC transporters were also evaluated but were negative by these assays. Transport of radioactive iron by the Feo system into the S. flexneri iron transport mutant was stimulated by the reducing agent ascorbate, consistent with Feo functioning as a ferrous transporter. Conversely, ascorbate inhibited transport by the Fbp system, suggesting that it transports ferric iron. The growth of V. cholerae strains carrying mutations in one or more of the potential iron transport genes indicated that both Feo and Fbp contribute to iron acquisition. However, a mutant defective in the vibriobactin, Fbp, and Feo systems was not attenuated in a suckling mouse model, suggesting that at least one other iron transport system can be used in vivo.

  7. Whole-genome survey of the putative ATP-binding cassette transporter family genes in Vitis vinifera.

    Directory of Open Access Journals (Sweden)

    Birsen Çakır

    Full Text Available The ATP-binding cassette (ABC protein superfamily constitutes one of the largest protein families known in plants. In this report, we performed a complete inventory of ABC protein genes in Vitis vinifera, the whole genome of which has been sequenced. By comparison with ABC protein members of Arabidopsis thaliana, we identified 135 putative ABC proteins with 1 or 2 NBDs in V. vinifera. Of these, 120 encode intrinsic membrane proteins, and 15 encode proteins missing TMDs. V. vinifera ABC proteins can be divided into 13 subfamilies with 79 "full-size," 41 "half-size," and 15 "soluble" putative ABC proteins. The main feature of the Vitis ABC superfamily is the presence of 2 large subfamilies, ABCG (pleiotropic drug resistance and white-brown complex homolog and ABCC (multidrug resistance-associated protein. We identified orthologs of V. vinifera putative ABC transporters in different species. This work represents the first complete inventory of ABC transporters in V. vinifera. The identification of Vitis ABC transporters and their comparative analysis with the Arabidopsis counterparts revealed a strong conservation between the 2 species. This inventory could help elucidate the biological and physiological functions of these transporters in V. vinifera.

  8. Whole-genome survey of the putative ATP-binding cassette transporter family genes in Vitis vinifera.

    Science.gov (United States)

    Çakır, Birsen; Kılıçkaya, Ozan

    2013-01-01

    The ATP-binding cassette (ABC) protein superfamily constitutes one of the largest protein families known in plants. In this report, we performed a complete inventory of ABC protein genes in Vitis vinifera, the whole genome of which has been sequenced. By comparison with ABC protein members of Arabidopsis thaliana, we identified 135 putative ABC proteins with 1 or 2 NBDs in V. vinifera. Of these, 120 encode intrinsic membrane proteins, and 15 encode proteins missing TMDs. V. vinifera ABC proteins can be divided into 13 subfamilies with 79 "full-size," 41 "half-size," and 15 "soluble" putative ABC proteins. The main feature of the Vitis ABC superfamily is the presence of 2 large subfamilies, ABCG (pleiotropic drug resistance and white-brown complex homolog) and ABCC (multidrug resistance-associated protein). We identified orthologs of V. vinifera putative ABC transporters in different species. This work represents the first complete inventory of ABC transporters in V. vinifera. The identification of Vitis ABC transporters and their comparative analysis with the Arabidopsis counterparts revealed a strong conservation between the 2 species. This inventory could help elucidate the biological and physiological functions of these transporters in V. vinifera.

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    Julia Gollhofer

    Full Text Available 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.

  11. Close Approximation of Putative α-Helices II, IV, VII, X, and XI in the Translocation Pathway of the Lactose Transport Protein of Streptococcus thermophilus

    NARCIS (Netherlands)

    Veenhoff, L.M.; Geertsma, E.R.; Poolman, B.; Knol, J.

    2000-01-01

    The lactose transport protein (LacS) of Streptococcus thermophilus belongs to a family of transporters in which putative α-helices II and IV have been implicated in cation binding and the coupled transport of the substrate and the cation. Here, the analysis of site-directed mutants shows that a posi

  12. The Putative Cellodextrin Transporter-like Protein CLP1 Is Involved in Cellulase Induction in Neurospora crassa*

    Science.gov (United States)

    Cai, Pengli; Wang, Bang; Ji, Jingxiao; Jiang, Yongsheng; Wan, Li; Tian, Chaoguang; Ma, Yanhe

    2015-01-01

    Neurospora crassa recently has become a novel system to investigate cellulase induction. Here, we discovered a novel membrane protein, cellodextrin transporter-like protein 1 (CLP1; NCU05853), a putative cellodextrin transporter-like protein that is a critical component of the cellulase induction pathway in N. crassa. Although CLP1 protein cannot transport cellodextrin, the suppression of cellulase induction by this protein was discovered on both cellobiose and Avicel. The co-disruption of the cellodextrin transporters cdt2 and clp1 in strain Δ3βG formed strain CPL7. With induction by cellobiose, cellulase production was enhanced 6.9-fold in CPL7 compared with Δ3βG. We also showed that the suppression of cellulase expression by CLP1 occurred by repressing the expression of cellodextrin transporters, particularly cdt1 expression. Transcriptome analysis of the hypercellulase-producing strain CPL7 showed that the cellulase expression machinery was dramatically stimulated, as were the cellulase enzyme genes including the inducer transporters and the major transcriptional regulators. PMID:25398875

  13. Functional importance of GGXG sequence motifs in putative reentrant loops of 2HCT and ESS transport proteins.

    Science.gov (United States)

    Dobrowolski, Adam; Lolkema, Juke S

    2009-08-11

    The 2HCT and ESS families are two families of secondary transporters. Members of the two families are unrelated in amino acid sequence but share similar hydropathy profiles, which suggest a similar folding of the proteins in membranes. Structural models show two homologous domains containing five transmembrane segments (TMSs) each, with a reentrant or pore loop between the fourth and fifth TMSs in each domain. Here we show that GGXG sequence motifs present in the putative reentrant loops are important for the activity of the transporters. Mutation of the conserved Gly residues to Cys in the motifs of the Na(+)-citrate transporter CitS in the 2HCT family and the Na(+)-glutamate transporter GltS in the ESS family resulted in strongly reduced transport activity. Similarly, mutation of the variable residue "X" to Cys in the N-terminal half of GltS essentially inactivated the transporter. The corresponding mutations in the N- and C-terminal halves of CitS reduced transport activity to 60 and 25% of that of the wild type, respectively. Residual activity of any of the mutants could be further reduced by treatment with the membrane permeable thiol reagent N-ethylmaleimide (NEM). The X to Cys mutation (S405C) in the cytoplasmic loop in the C-terminal half of CitS rendered the protein sensitive to the bulky, membrane impermeable thiol reagent 4-acetamido-4'-maleimidylstilbene-2,2'-disulfonic acid (AmdiS) added at the periplasmic side of the membrane, providing further evidence that this part of the loop is positioned between the transmembrane segments. The putative reentrant loop in the C-terminal half of the ESS family does not contain the GGXG motif, but a conserved stretch rich in Gly residues. Cysteine-scanning mutagenesis of a stretch of 18 residues in the GltS protein revealed two residues important for function. Mutant N356C was completely inactivated by treatment with NEM, and mutant P351C appeared to be the counterpart of mutant S405C of CitS; the mutant was

  14. Yersinia pestis TonB: Role in Iron, Heme, and Hemoprotein Utilization

    Science.gov (United States)

    Perry, Robert D.; Shah, Jessica; Bearden, Scott W.; Thompson, Jan M.; Fetherston, Jacqueline D.

    2003-01-01

    In Yersinia pestis, the siderophore-dependent yersiniabactin (Ybt) iron transport system and heme transport system (Hmu) have putative TonB-dependent outer membrane receptors. Here we demonstrate that hemin uptake and iron utilization from Ybt are TonB dependent. However, the Yfe iron and manganese transport system does not require TonB. PMID:12819108

  15. Phenotypic, Proteomic, and Genomic Characterization of a Putative ABC-Transporter Permease Involved in Listeria monocytogenes Biofilm Formation

    DEFF Research Database (Denmark)

    Zhu, Xinna; Liu, Weibing; Lametsch, René

    2011-01-01

    enhanced ability for biofilm formation as the LM-49 strain using a crystal violet staining assay. DNA microarrays and two-dimensional gel electrophoresis revealed 49 and 11 differentially expressed (twofold or more) genes or proteins in Δ1771, respectively. The transcriptomics study indicated that lm......The foodborne pathogen Listeria monocytogenes is able to form biofilms in food processing environments. Previously, we have reported that an lm.G_1771 gene (encoding a putative ABC-transporter permease) was involved in negative regulation of L. monocytogenes biofilm formation using LM-49, a biofilm......-enhanced mutant isolated on Tn917 mutagenesis (AEM 2008 p.7675–7683). Here, the possible action of this ABC-transporter permease in L. monocytogenes biofilm formation was characterized by phenotypic, proteomic, and genomic analyses using an lm.G_1771 gene deletant (Δ1771). The Δ1771 mutant exhibited the same...

  16. Identification of calcium-transporting ATPases of Entamoeba histolytica and cellular localization of the putative SERCA.

    Science.gov (United States)

    Martinez-Higuera, Aarón; Salas-Casas, Andrés; Calixto-Gálvez, Mercedes; Chávez-Munguía, Bibiana; Pérez-Ishiwara, D Guillermo; Ximénez, Cecilia; Rodríguez, Mario A

    2013-09-01

    Calcium has an important role on signaling of different cellular processes in the protozoa parasite Entamoeba histolytica, including development and pathogenesis. However, the systems that control calcium responses in this parasite are incompletely understood. Calcium-ATPases (Ca(2+)-ATPases) are proteins that play an important role in calcium homeostasis by catalyzing the active efflux of this ion from cytoplasm and are essential to the correct functioning of the cell machinery. Here, we reported the identification of five E. histolytica genes encoding putative Ca(2+)-ATPases, three related to PMCA, and two related to organellar ATPases. RT-PCR assays showed that all those genes are expressed in trophozoites and specific antibodies against the SERCA-like member located this protein in a continuous cytoplasmic network, supporting the hypothesis that it corresponds to the Ca(2+)-ATPase responsible to sequester calcium in the endoplasmic reticulum of this parasite.

  17. Tonoplast Sugar Transporters (SbTSTs) putatively control sucrose accumulation in sweet sorghum stems.

    Science.gov (United States)

    Bihmidine, Saadia; Julius, Benjamin T; Dweikat, Ismail; Braun, David M

    2016-01-01

    Carbohydrates are differentially partitioned in sweet versus grain sorghums. While the latter preferentially accumulate starch in the grain, the former primarily store large amounts of sucrose in the stem. Previous work determined that neither sucrose metabolizing enzymes nor changes in Sucrose transporter (SUT) gene expression accounted for the carbohydrate partitioning differences. Recently, 2 additional classes of sucrose transport proteins, Tonoplast Sugar Transporters (TSTs) and SWEETs, were identified; thus, we examined whether their expression tracked sucrose accumulation in sweet sorghum stems. We determined 2 TSTs were differentially expressed in sweet vs. grain sorghum stems, likely underlying the massive difference in sucrose accumulation. A model illustrating potential roles for different classes of sugar transport proteins in sorghum sugar partitioning is discussed.

  18. Divalent metal transporter, iron, and Parkinson's disease:A pathological relationship

    Institute of Scientific and Technical Information of China (English)

    Hyun-pil Lee; Xiongwei Zhu; Gang Liu; Shu G Chen; George Perry; Mark A Smith; Hyoung-gon Lee

    2010-01-01

    @@ Iron is an essential component of oxidative metabolism and a cofactor for a variety of enzymes. Because of its chemical properties as a transition metal, iron can serve both as an electron donor and acceptor and, as such, excess levels of free iron are toxic. Given this potential for toxicity, a number of pro-teins, including transferrin, transferrin receptor, and ferritin, tightly control iron transport, uptake, and storage in the central nervous system.

  19. Controls on radium transport by adsorption to iron minerals

    Science.gov (United States)

    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

  20. Two iron-regulated transporter (IRT) genes showed differential expression in poplar trees under iron or zinc deficiency.

    Science.gov (United States)

    Huang, Danqiong; Dai, Wenhao

    2015-08-15

    Two iron-regulated transporter (IRT) genes were cloned from the iron chlorosis resistant (PtG) and susceptible (PtY) Populus tremula 'Erecta' lines. Nucleotide sequence analysis showed no significant difference between PtG and PtY. The predicted proteins contain a conserved ZIP domain with 8 transmembrane (TM) regions. A ZIP signature sequence was found in the fourth TM domain. Phylogenetic analysis revealed that PtIRT1 was clustered with tomato and tobacco IRT genes that are highly responsible to iron deficiency. The PtIRT3 gene was clustered with the AtIRT3 gene that was related to zinc and iron transport in plants. Tissue specific expression indicated that PtIRT1 only expressed in the root, while PtIRT3 constitutively expressed in all tested tissues. Under iron deficiency, the expression of PtIRT1 was dramatically increased and a significantly higher transcript level was detected in PtG than in PtY. Iron deficiency also enhanced the expression of PtIRT3 in PtG. On the other hand, zinc deficiency down-regulated the expression of PtIRT1 and PtIRT3 in both PtG and PtY. Zinc accumulated significantly under iron-deficient conditions, whereas the zinc deficiency showed no significant effect on iron accumulation. A yeast complementation test revealed that the PtIRT1 and PtIRT3 genes could restore the iron uptake ability under the iron uptake-deficiency condition. The results will help understand the mechanisms of iron deficiency response in poplar trees and other woody species.

  1. Cloning and expression of SLC1OA4,a putative organic anion transport protein

    Institute of Scientific and Technical Information of China (English)

    Patrick L Splinter; Konstantinos N Lazaridis; Paul A Dawson; Nicholas F LaRusso

    2006-01-01

    AIM:To determine if novel bile acid transporters may be expressed in human tissues.METHODS:SLC10A1 (NTCP) was used as a probe to search the NCBI database for homology to previously uncharacterized ESTs. The homology search identified an EST (termed SLC10A4) that shares sequence identity with SLC10A1 and SLC10A2 (ASBT). We performed Northern blot analysis and RT-PCR to determine the tissue distribution of SLC10A4. SLC10A4 was cloned in frame with an epitope tag and overexpressed in CHO cells to determine cellular localization and functional analysis of bile acid uptake.RESULTS:Northern analysis revealed that SLC 10A4 mRNA is ubiquitously expressed fn human tissues with the highest levels of mRNA expression in brain,placenta, and liver. In SLC10A4-transfected CHO cells,immunoblotting analysis and immunofluorescence staining demonstrated a 49-kDa protein that is expressed at the plasma membrane and intracellular compartments.Functional analysis of SLC10A4 showed no significant taurocholate uptake in the presence of sodium when compared to untransfected CHO cells.CONCLUSION:To date, we have shown that this protein has no capacity to transport taurocholate relative to SLC1041; however, given its ubiquitous tissue distribution, it may play a more active role in transporting other endogenous organic anions.

  2. Measurement of multiple drug resistance transporter activity in putative cancer stem/progenitor cells.

    Science.gov (United States)

    Donnenberg, Vera S; Meyer, E Michael; Donnenberg, Albert D

    2009-01-01

    Multiple drug resistance, mediated by the expression and activity of ABC-transporters, is a major obstacle to antineoplastic therapy. Normal tissue stem cells and their malignant counterparts share MDR transporter activity as a major mechanism of self-protection. Although MDR activity is upregulated in response to substrate chemotherapeutic agents, it is also constitutively expressed on both normal tissue stem cells and a subset of tumor cells prior to the initiation of therapy, representing a built-in obstacle to therapeutic ratio. Constitutive and induced MDR activity can be detected in cellular subsets of disaggregated tissues, using the fluorescent substrates Rhodamine 123 and Hoechst 33342 for ABCB1 (also known as P-gp and MDR1) and ABCG2 (BCRP1). In this chapter, we will describe the complete procedure for the detection of MDR activity, including: (1) Preparing single-cell suspensions from tumor and normal tissue specimens; (2) An efficient method to perform cell surface marker staining on large numbers of cells; (3) Flow cytometer setup and controls; (4) Simultaneous measurement of Hoechst 33342 and Rhodamine123 transport; and (5) Data acquisition and analysis.

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

    Science.gov (United States)

    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.

  4. SmbFT, a putative ABC transporter complex, confers protection against the lantibiotic Smb in Streptococci.

    Science.gov (United States)

    Biswas, Saswati; Biswas, Indranil

    2013-12-01

    Streptococcus mutans, a dental pathogen, secretes different kinds of lantibiotic and nonlantibiotic bacteriocins. For self-protection, a bacteriocin producer strain must possess one or more cognate immunity mechanisms. We report here the identification of one such immunity complex in S. mutans strain GS-5 that confers protection against Smb, a two-component lantibiotic. The immunity complex that we identified is an ABC transporter composed of two proteins: SmbF (the ATPase component) and SmbT (the permease component). Both of the protein-encoding genes are located within the smb locus. We show that GS-5 becomes sensitized to Smb upon deletion of smbT, which makes the ABC transporter nonfunctional. To establish the role SmbFT in providing immunity, we heterologously expressed this ABC transporter complex in four different sensitive streptococcal species and demonstrated that it can confer resistance against Smb. To explore the specificity of SmbFT in conferring resistance, we tested mutacin IV (a nonlantibiotic), nisin (a single peptide lantibiotics), and three peptide antibiotics (bacitracin, polymyxin B, and vancomycin). We found that SmbFT does not recognize these structurally different peptides. We then tested whether SmbFT can confer protection against haloduracin, another two-component lantibiotic that is structurally similar to Smb; SmbFT indeed conferred protection against haloduracin. SmbFT can also confer protection against an uncharacterized but structurally similar lantibiotic produced by Streptococcus gallolyticus. Our data suggest that SmbFT truly displays immunity function and confer protection against Smb and structurally similar lantibiotics.

  5. A Golgi-localized MATE transporter mediates iron homoeostasis under osmotic stress in Arabidopsis.

    Science.gov (United States)

    Seo, Pil Joon; Park, Jungmin; Park, Mi-Jeong; Kim, Youn-Sung; Kim, Sang-Gyu; Jung, Jae-Hoon; Park, Chung-Mo

    2012-03-15

    Iron is an essential micronutrient that acts as a cofactor in a wide variety of pivotal metabolic processes, such as the electron transport chain of respiration, photosynthesis and redox reactions, in plants. However, its overload exceeding the cellular capacity of iron binding and storage is potentially toxic to plant cells by causing oxidative stress and cell death. Consequently, plants have developed versatile mechanisms to maintain iron homoeostasis. Organismal iron content is tightly regulated at the steps of uptake, translocation and compartmentalization. Whereas iron uptake is fairly well understood at the cellular and organismal levels, intracellular and intercellular transport is only poorly understood. In the present study, we show that a MATE (multidrug and toxic compound extrusion) transporter, designated BCD1 (BUSH-AND-CHLOROTIC-DWARF 1), contributes to iron homoeostasis during stress responses and senescence in Arabidopsis. The BCD1 gene is induced by excessive iron, but repressed by iron deficiency. It is also induced by cellular and tissue damage occurring under osmotic stress. The activation-tagged mutant bcd1-1D exhibits leaf chlorosis, a typical symptom of iron deficiency. The chlorotic lesion of the mutant was partially recovered by iron feeding. Whereas the bcd1-1D mutant accumulated a lower amount of iron, the iron level was elevated in the knockout mutant bcd1-1. The BCD1 protein is localized to the Golgi complex. We propose that the BCD1 transporter plays a role in sustaining iron homoeostasis by reallocating excess iron released from stress-induced cellular damage.

  6. Physiological and Pathological Role of Alpha-Synuclein in Parkinson’s Disease through Iron Mediated Oxidative Stress; The Role of a Putative Iron-Responsive Element

    OpenAIRE

    David Olivares; Xudong Huang; Lars Branden; Greig, Nigel H.; Jack T. Rogers

    2009-01-01

    Parkinson’s disease (PD) is the second most common progressive neurodegenerative disorder after Alzheimer’s disease (AD) and represents a large health burden to society. Genetic and oxidative risk factors have been proposed as possible causes, but their relative contribution remains unclear. Dysfunction of alpha-synuclein (\\(\\alpha\\)-syn) has been associated with PD due to its increased presence, together with iron, in Lewy bodies. Brain oxidative damage caused by iron may be partly mediated ...

  7. Acquisition, transport, and storage of iron by pathogenic fungi.

    Science.gov (United States)

    Howard, D H

    1999-07-01

    Iron is required by most living systems. A great variety of means of acquisition, avenues of uptake, and methods of storage are used by pathogenic fungi to ensure a supply of the essential metal. Solubilization of insoluble iron polymers is the first step in iron assimilation. The two methods most commonly used by microorganisms for solubilization of iron are reduction and chelation. Reduction of ferric iron to ferrous iron by enzymatic or nonenzymatic means is a common mechanism among pathogenic yeasts. Under conditions of iron starvation, many fungi synthesize iron chelators known as siderophores. Two classes of compounds that function in iron gathering are commonly observed: hydroxamates and polycarboxylates. Two major responses to iron stress in fungi are a high-affinity ferric iron reductase and siderophore synthesis. Regulation of these two mechanisms at the molecular level has received attention. Uptake of siderophores is a diverse process, which varies among the different classes of compounds. Since free iron is toxic, it must be stored for further metabolic use. Polyphosphates, ferritins, and siderophores themselves have been described as storage molecules. The iron-gathering mechanisms used by a pathogen in an infected host are largely unknown and can only be posited on the basis of in vitro studies at present.

  8. Boron transport in Eucalyptus. 2. Identification in silico of a putative boron transporter for xylem loading in eucalypt

    Directory of Open Access Journals (Sweden)

    Douglas Silva Domingues

    2005-01-01

    Full Text Available Boron (B is a low mobility plant micronutrient whose molecular mechanisms of absorption and translocation are still controversial. Many factors are involved in tolerance to Boron excess or deficiency. Recently, the first protein linked to boron transport in biological systems, BOR1, was characterized in Arabidopsis thaliana. This protein is involved in boron xylem loading and is similar to bicarbonate transporters found in animals. There are indications that BOR1 is a member of a conserved protein family in plants. In this work, FORESTS database was used to identify sequences similar to this protein family, looking for a probable BOR1 homolog in eucalypt. We found five consensus sequences similar to BOR1; three of them were then used in multiple alignment analysis. Based on amino acid similarity and in silico expression patterns, a consensus sequence was identified as a candidate BOR1 homolog, helping deeper experimental assays that could identify the function of this protein family in Eucalyptus.

  9. AmSUT1, a sucrose transporter in collection and transport phloem of the putative symplastic phloem loader Alonsoa meridionalis.

    Science.gov (United States)

    Knop, Christian; Stadler, Ruth; Sauer, Norbert; Lohaus, Gertrud

    2004-01-01

    A sucrose (Suc) transporter cDNA has been cloned from Alonsoa meridionalis, a member of the Scrophulariaceae. This plant species has an open minor vein configuration and translocates mainly raffinose and stachyose in addition to Suc in the phloem (C. Knop, O. Voitsekhovskaja, G. Lohaus [2001] Planta 213: 80-91). These are typical properties of symplastic phloem loaders. For functional characterization, AmSUT1 cDNA was expressed in bakers' yeast (Saccharomyces cerevisiae). Substrate and inhibitor specificities, energy dependence, and Km value of the protein agree well with the properties measured for other Suc transporters of apoplastic phloem loaders. A polyclonal antiserum against the 17 N-terminal amino acids of the A. meridionalis Suc transporter AmSUT1 was used to determine the cellular localization of the AmSUT1 protein. Using fluorescence labeling on sections from A. meridionalis leaves and stems, AmSUT1 was localized exclusively in phloem cells. Further histological characterization identified these cells as companion cells and sieve elements. p-Chloromercuribenzenesulfonic acid affected the sugar exudation of cut leaves in such a way that the exudation rates of Suc and hexoses decreased, whereas those of raffinose and stachyose increased. The data presented indicate that phloem loading of Suc and retrieval of Suc in A. meridionalis are at least partly mediated by the activity of AmSUT1 in addition to symplastic phloem loading.

  10. Gravistimulation changes expression of genes encoding putative carrier proteins of auxin polar transport in etiolated pea epicotyls

    Science.gov (United States)

    Hoshino, T.; Hitotsubashi, R.; Miyamoto, K.; Tanimoto, E.; Ueda, J.

    STS-95 space experiment has showed that auxin polar transport in etiolated epicotyls of pea (Pisum sativum L. cv. Alaska) seedlings is controlled by gravistimulation. In Arabidopsis thaliana auxin polar transport has considered to be regulated by efflux and influx carrier proteins in plasma membranes, AtPIN1 and AtAUX1, respectively. In order to know how gravistimuli control auxin polar transport in etiolated pea epicotyls at molecular levels, strenuous efforts have been made, resulting in successful isolation of full-length cDNAs of a putative auxin efflux and influx carriers, PsPIN2 and PsAUX1, respectively. Significantly high levels in homology were found on nucleotide and deduced amino acid sequences among PsPIN2, PsPIN1 (accession no. AY222857, Chawla and DeMason, 2003) and AtPINs, and also among PsAUX1, AtAUX1 and their related genes. Phylogenetic analyses based on the deduced amino acid sequences revealed that PsPIN2 belonged to a subclade including AtPIN3, AtPIN4 relating to lateral transport of auxin, while PsPIN1 belonged to the same clade as AtPIN1 relating to auxin polar transport. In the present study, we examined the effects of gravistimuli on the expression of PsPINs and PsAUX1 in etiolated pea seedlings by northern blot analysis. Expression of PsPIN1, PsPIN2 and PsAUX1 in hook region of 3.5-d-old etiolated pea seedlings grown under simulated microgravity conditions on a 3-D clinostat increased as compared with that of the seedlings grown under 1 g conditions. On the other hand, that of PsPIN1 and PsAUX1 in the 1st internode region under simulated microgravity conditions on a 3-D clinostat also increased, while that of PsPIN2 was affected little. These results suggest that expression of PsPIN1, PsPIN2 and PsAUX1 regulating polar/lateral transport of auxin is substantially under the control of gravity. A possible role of PsPINs and PsAUX1 of auxin polar transport in etiolated pea seedlings will also be discussed.

  11. Optimization for vehicle scheduling in iron and steel works based on semi-trailer swap transport

    Institute of Scientific and Technical Information of China (English)

    CHENG Yao-rong; LIANG Bo; ZHOU Mei-hua

    2010-01-01

    In order to solve internal logistics problems of iron and steel works,such as low transportation efficiency of cehicles and high transportation cost,the production process and traditional transportation style of iron and steel work were introduced.The internal transport tasks of iron and steel works were grouped based on cluster analysis according to demand time of the transportation. An improved vehicle scheduling model of semi-trailer swap transport among loading nodes and unloading nodes in one task group was set up.The algorithm was designed to silve the vehicle routing problem with simultaneous pick-up and delivery (CRPSPD)problem based on semi-trailer swap transport.A solving program was written by MATLAB software and the method to figure out the optimal path of each grouping was obtainde.The dropping and pulling transportation plan of the tractor wan designed.And an decerase the numbers of semi-trailer swap transport in iron and steel works was given.The results indicate that semi-trailer swap transport can steel works,and the total distance traveled reduces by 43.5%.The semi-trailer swap transport can help the iron and steel works develop the productiong in intension.

  12. Cloning and Expression Pattern of a Gene Encoding a Putative Plastidic ATP/ADP Transporter from Helianthus tuberosus L.

    Institute of Scientific and Technical Information of China (English)

    Kun MENG; Tuan-Jie CHANG; Xiang LIU; Song-Biao CHEN; Yong-Qin WANG; Ai-Jun SUN; Hong-Lin XU; Xiao-Li WEI; Zhen ZHU

    2005-01-01

    Herein, we report the cloning and molecular characterization of a full cDNA encoding a putative plastidic ATP/ADP transporter, designated HtAATP, for Helianthus tuberosus L. The ATP/ADP translocator protein was isolated from the tuber-cDNA library of H. tuberosus for the first time. The predicted HtAATP protein was judged as a plastidic ATP/ADP translocator protein from its high homology at the amino acid sequence level to the two Arabidopsis thaliana plastidic ATP/ADP translocator proteins AATP1 and AATP2 (84.8% and 79.9% identity, respectively). Amino acid sequence analysis of the primary structure of HtAATP revealed that it belonged to the plastidic ATP/ADP transporter family. Hydropathy prediction indicated that HtAATP gene product is a highly hydrophobic membrane protein that contains 10 transmembrane domains to form a spanning topology. Southern blotting analysis showed that the HtAATP gene is a single-copy gene in the H. tuberosus genome. Tissue distribution analysis showed that the HtAATP gene is prominently expressed in sink tissues. A stable expression pattern in tubers at different developmental stages implies an active involvement of HtAATP during carbohydrate formation.

  13. Thickness Optimisation of Textiles Subjected to Heat and Mass Transport during Ironing

    Directory of Open Access Journals (Sweden)

    Korycki Ryszard

    2016-09-01

    Full Text Available Let us next analyse the coupled problem during ironing of textiles, that is, the heat is transported with mass whereas the mass transport with heat is negligible. It is necessary to define both physical and mathematical models. Introducing two-phase system of mass sorption by fibres, the transport equations are introduced and accompanied by the set of boundary and initial conditions. Optimisation of material thickness during ironing is gradient oriented. The first-order sensitivity of an arbitrary objective functional is analysed and included in optimisation procedure. Numerical example is the thickness optimisation of different textile materials in ironing device.

  14. The Novel Neuronal Ceroid Lipofuscinosis Gene MFSD8 Encodes a Putative Lysosomal Transporter

    Science.gov (United States)

    Siintola, Eija ; Topcu, Meral ; Aula, Nina ; Lohi, Hannes ; Minassian, Berge A. ; Paterson, Andrew D. ; Liu, Xiao-Qing ; Wilson, Callum ; Lahtinen, Ulla ; Anttonen, Anna-Kaisa ; Lehesjoki, Anna-Elina 

    2007-01-01

    The late-infantile–onset forms are the most genetically heterogeneous group among the autosomal recessively inherited neurodegenerative disorders, the neuronal ceroid lipofuscinoses (NCLs). The Turkish variant was initially considered to be a distinct genetic entity, with clinical presentation similar to that of other forms of late-infantile–onset NCL (LINCL), including age at onset from 2 to 7 years, epileptic seizures, psychomotor deterioration, myoclonus, loss of vision, and premature death. However, Turkish variant LINCL was recently found to be genetically heterogeneous, because mutations in two genes, CLN6 and CLN8, were identified to underlie the disease phenotype in a subset of patients. After a genomewide scan with single-nucleotide–polymorphism markers and homozygosity mapping in nine Turkish families and one Indian family, not linked to any of the known NCL loci, we mapped a novel variant LINCL locus to chromosome 4q28.1-q28.2 in five families. We identified six different mutations in the MFSD8 gene (previously denoted “MGC33302”), which encodes a novel polytopic 518–amino acid membrane protein that belongs to the major facilitator superfamily of transporter proteins. MFSD8 is expressed ubiquitously, with several alternatively spliced variants. Like the majority of the previously identified NCL proteins, MFSD8 localizes mainly to the lysosomal compartment. However, the function of MFSD8 remains to be elucidated. Analysis of the genome-scan data suggests the existence of at least three more genes in the remaining five families, further corroborating the great genetic heterogeneity of LINCLs. PMID:17564970

  15. Nitrate-dependent iron oxidation limits iron transport in anoxic ocean regions

    Science.gov (United States)

    Scholz, Florian; Löscher, Carolin R.; Fiskal, Annika; Sommer, Stefan; Hensen, Christian; Lomnitz, Ulrike; Wuttig, Kathrin; Göttlicher, Jörg; Kossel, Elke; Steininger, Ralph; Canfield, Donald E.

    2016-11-01

    Iron is an essential element for life on Earth and limits primary production in large parts of the ocean. Oxygen-free continental margin sediments represent an important source of bioavailable iron to the ocean, yet little of the iron released from the seabed reaches the productive sea surface. Even in the anoxic water of oxygen minimum zones, where iron solubility should be enhanced, most of the iron is rapidly re-precipitated. To constrain the mechanism(s) of iron removal in anoxic ocean regions we explored the sediment and water in the oxygen minimum zone off Peru. During our sampling campaign the water column featured two distinct redox boundaries separating oxic from nitrate-reducing (i.e., nitrogenous) water and nitrogenous from weakly sulfidic water. The sulfidic water mass in contact with the shelf sediment contained elevated iron concentrations >300 nM. At the boundary between sulfidic and nitrogenous conditions, iron concentrations dropped sharply to nitrate reduction (narG). Part of this upregulation was related to the activity of known iron-oxidizing bacteria. Collectively, our data suggest that iron oxidation and removal is induced by nitrate-reducing microbes, either enzymatically through anaerobic iron oxidation or by providing nitrite for an abiotic reaction. Given the important role that iron plays in nitrogen fixation, photosynthesis and respiration, nitrate-dependent iron oxidation likely represents a key-link between the marine biogeochemical cycles of nitrogen, oxygen and carbon.

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

    Science.gov (United States)

    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.

  17. Raman hyperspectral imaging of iron transport across membranes in cells

    Science.gov (United States)

    Das, Anupam; Costa, Xavier Felipe; Khmaladze, Alexander; Barroso, Margarida; Sharikova, Anna

    2016-09-01

    Raman scattering microscopy is a powerful imaging technique used to identify chemical composition, structural and conformational state of molecules of complex samples in biology, biophysics, medicine and materials science. In this work, we have shown that Raman techniques allow the measurement of the iron content in protein mixtures and cells. Since the mechanisms of iron acquisition, storage, and excretion by cells are not completely understood, improved knowledge of iron metabolism can offer insight into many diseases in which iron plays a role in the pathogenic process, such as diabetes, neurodegenerative diseases, cancer, and metabolic syndrome. Understanding of the processes involved in cellular iron metabolism will improve our knowledge of cell functioning. It will also have a big impact on treatment of diseases caused by iron deficiency (anemias) and iron overload (hereditary hemochromatosis). Previously, Raman studies have shown substantial differences in spectra of transferrin with and without bound iron, thus proving that it is an appropriate technique to determine the levels of bound iron in the protein mixture. We have extended these studies to obtain hyperspectral images of transferrin in cells. By employing a Raman scanning microscope together with spectral detection by a highly sensitive back-illuminated cooled CCD camera, we were able to rapidly acquire and process images of fixed cells with chemical selectivity. We discuss and compare various methods of hyperspectral Raman image analysis and demonstrate the use of these methods to characterize cellular iron content without the need for dye labeling.

  18. End-on and side-on peroxo derivatives of non-heme iron complexes with pentadentate ligands : Models for putative intermediates in biological iron/dioxygen chemistry

    NARCIS (Netherlands)

    Roelfes, G; Vrajmasu, [No Value; Ho, RYN; Rohde, JU; Zondervan, C; la Crois, RM; Schudde, EP; Lutz, M; Spek, AL; Hage, R; Feringa, BL; Munck, E; Que, L; Vrajmasu, Vladislav; Ho, Raymond Y.N.; Rohde, Jan-Uwe; Crois, Rene M. la; Spek, Anthony L.; Que, Jr.; Feringa, Bernard

    2003-01-01

    Mononuclear iron(III) species with end-on and side-on peroxide have been proposed or identified in the catalytic cycles of the antitumor drug bleomycin and a variety of enzymes, such as cytochrome P450 and Rieske dioxygenases, Only recently have biomimetic analogues of such reactive species been, ge

  19. Nitrate-dependent iron oxidation limits iron transport in anoxic ocean regions

    DEFF Research Database (Denmark)

    Scholz, Florian; Löscher, Carolin; Fiskal, Annika

    2016-01-01

    Iron is an essential element for life on Earth and limits primary production in large parts of the ocean. Oxygen-free continental margin sediments represent an important source of bioavailable iron to the ocean, yet little of the iron released from the seabed reaches the productive sea surface...

  20. Heme and non-heme iron transporters in non-polarized and polarized cells

    Directory of Open Access Journals (Sweden)

    Yasui Yumiko

    2010-06-01

    Full Text Available Abstract Background Heme and non-heme iron from diet, and recycled iron from hemoglobin are important products of the synthesis of iron-containing molecules. In excess, iron is potentially toxic because it can produce reactive oxygen species through the Fenton reaction. Humans can absorb, transport, store, and recycle iron without an excretory system to remove excess iron. Two candidate heme transporters and two iron transporters have been reported thus far. Heme incorporated into cells is degraded by heme oxygenases (HOs, and the iron product is reutilized by the body. To specify the processes of heme uptake and degradation, and the reutilization of iron, we determined the subcellular localizations of these transporters and HOs. Results In this study, we analyzed the subcellular localizations of 2 isoenzymes of HOs, 4 isoforms of divalent metal transporter 1 (DMT1, and 2 candidate heme transporters--heme carrier protein 1 (HCP1 and heme responsive gene-1 (HRG-1--in non-polarized and polarized cells. In non-polarized cells, HCP1, HRG-1, and DMT1A-I are located in the plasma membrane. In polarized cells, they show distinct localizations: HCP1 and DMT1A-I are located in the apical membrane, whereas HRG-1 is located in the basolateral membrane and lysosome. 16Leu at DMT1A-I N-terminal cytosolic domain was found to be crucial for plasma membrane localization. HOs are located in smooth endoplasmic reticulum and colocalize with NADPH-cytochrome P450 reductase. Conclusions HCP1 and DMT1A-I are localized to the apical membrane, and HRG-1 to the basolateral membrane and lysosome. These findings suggest that HCP1 and DMT1A-I have functions in the uptake of dietary heme and non-heme iron. HRG-1 can transport endocytosed heme from the lysosome into the cytosol. These localization studies support a model in which cytosolic heme can be degraded by HOs, and the resulting iron is exported into tissue fluids via the iron transporter ferroportin 1, which is

  1. The expression of superoxide dismutase (SOD) and a putative ABC transporter permease is inversely correlated during biofilm formation in Listeria monocytogenes 4b G

    Science.gov (United States)

    Little is known about the molecular basis of biofilm formation in Listeria monocytogenes. The superoxide dismutase (SOD) of the deletion mutant of lm.G_1771 gene, which encodes for a putative ABC_transporter permease, is highly expressed in biofilm. In this study, the sod gene deletion mutant delta ...

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

    Science.gov (United States)

    Johnson, Raymond H.; Tutu, Hlanganani; Brown, Adrian; Figueroa, Linda; Wolkersdorfer, Christian

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

    Directory of Open Access Journals (Sweden)

    Esther G. Meyron-Holtz

    2014-08-01

    Full Text Available 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.

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

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  6. Expression of Iron-Related Proteins at the Neurovascular Unit Supports Reduction and Reoxidation of Iron for Transport Through the Blood-Brain Barrier

    DEFF Research Database (Denmark)

    Burkhart, Annette; Skjørringe, Tina; Johnsen, Kasper Bendix;

    2015-01-01

    The mechanisms for iron transport through the blood-brain barrier (BBB) remain a controversy. We analyzed for expression of mRNA and proteins involved in oxidation and transport of iron in isolated brain capillaries from dietary normal, iron-deficient, and iron-reverted rats. The expression...... was also investigated in isolated rat brain endothelial cells (RBECs) and in immortalized rat brain endothelial (RBE4) cells grown as monoculture or in hanging culture inserts with defined BBB properties. Transferrin receptor 1, ferrireductases Steap 2 and 3, divalent metal transporter 1 (DMT1...... cells provide the machinery for receptor-mediated uptake of ferric iron-containing transferrin. Ferric iron can then undergo reduction to ferrous iron by ferrireductases inside endosomes followed by DMT1-mediated pumping into the cytosol and subsequently cellular export by ferroportin. The expression...

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

    Science.gov (United States)

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

    2015-01-01

    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. 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. 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. 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.

  8. Arabidopsis SOI33/AtENT8 Gene Encodes a Putative Equilibrative Nucleoside Transporter That Is Involved in Cytokinin Transport In Planta

    Institute of Scientific and Technical Information of China (English)

    Jiaqiang SUN; Naoya HIROSE; Xingchun WANG; Pei WEN; Li XUE; Hitoshi SAKAKIBARA; Jianru ZUO

    2005-01-01

    The plant phytohormone cytokinin plays an important role in many facets of plant growth and development by regulating cell division and differentiation. Recent studies have shed significant light into the mechanisms of cytokinin metabolism and signaling. However, little is known about how the hormone is transported in planta, although it has been proposed that the hormone is presumably transported in nucleoside-conjugated forms. Here, we report the identification and characterization of cytokinin transport ers in Arabidopsis. We previously reported that a gain-of-function mutation in the PGA22/AtIPT8 gene caused overproduction of cytokinins in planta. In an effort to screen for suppressor of pga22/atipt8 (soi) mutants, we identified a mutant soi33-1. Molecular and genetic analyses indicated that SOI33 encodes a putative equilibrative nucleoside transporter (ENT), previously designated as AtENT8. Members of this small gene family are presumed to be involved in the transport of nucleosides in eukaryotic cells. Under conditions of nitrogen starvation, loss-of-function mutations in SOI33/AtENT8 or in a related gene AtENT3 cause a reduced sensitivity to the nucleoside-type cytokinins isopentenyladenine riboside (iPR) and trans zeatin riboside (tZR), but display a normal response to the free base-type cytokinins isopentenyladenine (iP) and trans-zeatin (tZ). Conversely, overexpression of SOI33/AtENT8 renders transgenic plants hyper sensitive to iPR but not to iP. An in planta measurement experiment indicated that uptake efficiency of 3H labeled iPR was reduced more than 40% in soi33 and atent3 mutants. However, a mutation inAtENT1 had no substantial effect on the cytokinin response and iPR uptake efficiency. Our results suggest that SOI33/ AtENT8 and AtENT3 are involved in the transport of nucleoside-type cytokinins in Arabidopsis.

  9. Probing the putative active site of YjdL: an unusual proton-coupled oligopeptide transporter from E. coli.

    Directory of Open Access Journals (Sweden)

    Johanne Mørch Jensen

    Full Text Available YjdL from E. coli is an unusual proton-coupled oligopeptide transporter (POT. Unlike prototypical POTs, dipeptides are preferred over tripeptides, in particular dipeptides with a positively charged C-terminal residue. To further understand this difference in peptide specificity, the sequences of YjdL and YdgR, a prototypical E. coli POT, were compared in light of the crystal structure of a POT from Shewanella oneidensis. Several residues found in the putative active site were mutated and the activities of the mutated variants were assessed in terms of substrate uptake assays, and changes in specificity in terms of uptake inhibition. Most strikingly, changing the YjdL specific Asp392 to the conserved Ser in YjdL obliterated the preference for a positively charged C-terminal residue. Based on this unique finding and previously published results indicating that the dipeptide N-terminus may interact with Glu388, a preliminary orientation model of a dipeptide in the YjdL cavity is presented. Single site mutations of particularly Ala281 and Trp278 support the presented orientation. A dipeptide bound in the cavity of YjdL appears to be oriented such that the N-terminal side chain protrudes into a sub pocket that opens towards the extracellular space. The C-terminal side chain faces in the opposite direction into a sub pocket that faces the cytoplasm. These data indicated a stabilizing effect on a bulky N-terminal residue by an Ala281Phe variant and on the dipeptide backbone by Trp278. In the presented orientation model, Tyr25 and Tyr58 both appear to be in proximity of the dipeptide backbone while Lys117 appears to be in proximity of the peptide C-terminus. Mutational studies of these conserved residues highlight their functional importance.

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

    Science.gov (United States)

    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...

  11. Molecular cloning, immunochemical localization to the vacuole, and expression in transgenic yeast and tobacco of a putative sugar transporter from sugar beet.

    Science.gov (United States)

    Chiou, T J; Bush, D R

    1996-02-01

    Several plant genes have been cloned that encode members of the sugar transporter subgroup of the major facilitator superfamily of transporters. Here we report the cloning, expression, and membrane localization of one of these porters found in sugar beet (Beta vulgaris L.). This clone, cDNA-1, codes for a protein with 490 amino acids and an estimated molecular mass of 54 kD. The predicted membrane topology and sequence homology suggest that cDNA-1 is a member of the sugar transporter family. RNA gel blot analysis revealed that this putative sugar transporter is expressed in all vegetative tissues and expression increases with development in leaves. DNA gel blot analysis indicated that multiple gene copies exist for this putative sugar transporter in the sugar beet genome. Antibodies directed against small peptides representing the N- and C-terminal domains of the cDNA1 protein identified a 40-kD polypeptide in microsomes isolated from cDNA-1-transformed yeast (Saccharomyces cerevisiae). Moreover, the same protein was identified in sugar beet and transgenic tobacco (Nicotaina tobacum L.) membrane fractions. Detailed analysis of the transporter's distribution across linear sucrose gradients and flotation centrifugations showed that it co-migrates with tonoplast membrane markers. We conclude that this carrier is located on the tonoplast membrane and that it may mediate sugar partitioning between the vacuole and cytoplasmic compartments.

  12. Gene ercA, encoding a putative iron-containing alcohol dehydrogenase, is involved in regulation of ethanol utilization in Pseudomonas aeruginosa.

    Science.gov (United States)

    Hempel, Niels; Görisch, Helmut; Mern, Demissew S

    2013-09-01

    Several two-component regulatory systems are known to be involved in the signal transduction pathway of the ethanol oxidation system in Pseudomonas aeruginosa ATCC 17933. These sensor kinases and response regulators are organized in a hierarchical manner. In addition, a cytoplasmic putative iron-containing alcohol dehydrogenase (Fe-ADH) encoded by ercA (PA1991) has been identified to play an essential role in this regulatory network. The gene ercA (PA1991) is located next to ercS, which encodes a sensor kinase. Inactivation of ercA (PA1991) by insertion of a kanamycin resistance cassette created mutant NH1. NH1 showed poor growth on various alcohols. On ethanol, NH1 grew only with an extremely extended lag phase. During the induction period on ethanol, transcription of structural genes exa and pqqABCDEH, encoding components of initial ethanol oxidation in P. aeruginosa, was drastically reduced in NH1, which indicates the regulatory function of ercA (PA1991). However, transcription in the extremely delayed logarithmic growth phase was comparable to that in the wild type. To date, the involvement of an Fe-ADH in signal transduction processes has not been reported.

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

    Science.gov (United States)

    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 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 surface was within a factor of 2 at most

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

    Directory of Open Access Journals (Sweden)

    R. Wang

    2015-03-01

    Full Text Available 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, 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

  15. Transcriptional activation and localization of expression of Brassica juncea putative metal transport protein BjMTP1

    Directory of Open Access Journals (Sweden)

    Salt David E

    2007-06-01

    Full Text Available Abstract Background Metal hyperaccumulators, including various Thlaspi species, constitutively express the putative metal transporter MTP1 to high levels in shoots. Here we present data on the transcriptional regulation and localization of expression of the homologous gene BjMTP1 in Brassica juncea. Though B. juncea lacks the ability to hyperaccumulate metals, its relatively high biomass, rapid growth and relatedness to true metal hyperaccumulating plants makes it a promising starting point for the development of plants for phytoremediation. Our goal in this study is to determine the transcriptional regulation of MTP1 in order to start to better understanding the physiological role of MTP1 in B. juncea. Results Steady-state mRNA levels of BjMTP1 were found to be enhanced 8.8, 5.9, and 1.6-fold in five-day-old B. juncea seedlings after exposure to Ni2+, Cd2+ or Zn2+, respectively. This was also reflected in enhanced GUS activity in B. juncea seedlings transformed with BjMTP1 promoter::GUSPlus after exposure to these metals over a similar range of toxicities from mild to severe. However, no increase in GUS activity was observed after exposure of seedlings to cold or heat stress, NaCl or hydrogen peroxide. GUS expression in Ni2+ treated seedlings was localized in roots, particularly in the root-shoot transition zone. In four- week- old transgenic plants BjMTP1 promoter activity also primarily increased in roots in response to Ni2+ or Cd2+ in plants transformed with either GUS or mRFP1 as reporter genes, and expression was localized to the secondary xylem parenchyma. In leaves, BjMTP1 promoter activity in response to Ni2+ or Cd2+ spiked after 24 h then decreased. In shoots GUS expression was prominently present in the vasculature of leaves, and floral parts. Conclusion Our studies establish that a 983 bp DNA fragment upstream of the BjMTP1 translational start site is sufficient for the specific activation by Ni2+ and Cd2+ of BjMTP1 expression

  16. Transcriptional activation and localization of expression of Brassica juncea putative metal transport protein BjMTP1

    Science.gov (United States)

    Muthukumar, Balasubramaniam; Yakubov, Bakhtiyor; Salt, David E

    2007-01-01

    Background Metal hyperaccumulators, including various Thlaspi species, constitutively express the putative metal transporter MTP1 to high levels in shoots. Here we present data on the transcriptional regulation and localization of expression of the homologous gene BjMTP1 in Brassica juncea. Though B. juncea lacks the ability to hyperaccumulate metals, its relatively high biomass, rapid growth and relatedness to true metal hyperaccumulating plants makes it a promising starting point for the development of plants for phytoremediation. Our goal in this study is to determine the transcriptional regulation of MTP1 in order to start to better understanding the physiological role of MTP1 in B. juncea. Results Steady-state mRNA levels of BjMTP1 were found to be enhanced 8.8, 5.9, and 1.6-fold in five-day-old B. juncea seedlings after exposure to Ni2+, Cd2+ or Zn2+, respectively. This was also reflected in enhanced GUS activity in B. juncea seedlings transformed with BjMTP1 promoter::GUSPlus after exposure to these metals over a similar range of toxicities from mild to severe. However, no increase in GUS activity was observed after exposure of seedlings to cold or heat stress, NaCl or hydrogen peroxide. GUS expression in Ni2+ treated seedlings was localized in roots, particularly in the root-shoot transition zone. In four- week- old transgenic plants BjMTP1 promoter activity also primarily increased in roots in response to Ni2+ or Cd2+ in plants transformed with either GUS or mRFP1 as reporter genes, and expression was localized to the secondary xylem parenchyma. In leaves, BjMTP1 promoter activity in response to Ni2+ or Cd2+ spiked after 24 h then decreased. In shoots GUS expression was prominently present in the vasculature of leaves, and floral parts. Conclusion Our studies establish that a 983 bp DNA fragment upstream of the BjMTP1 translational start site is sufficient for the specific activation by Ni2+ and Cd2+ of BjMTP1 expression primarily in roots. Activation of

  17. Experimental research on the behavior of the pneumatic transport of fine-grained iron

    Science.gov (United States)

    Andrei, V.; Hritac, M.; Constantin, N.; Dobrescu, C.

    2017-01-01

    Mixed injection of fine-grained iron ore and pulverized coal in the furnace, involves determining the behavior of these materials during pneumatic transport in a dense state through the pipe and setting possibilities for adjusting the flow rate of material transported with the corresponding values of the process. Parameters of the pneumatic transport were determined for the main types of iron ore and chalk used in Arcelor Mittal Galati. Outside the intended purpose of injecting iron ore and flux, it was considered also the experimental check of the possibility for injecting ilmenite in the furnace for crucible protection purpose. The possibility of injecting cinder mill into the furnace was also considered. Injecting cinder could be taken into account for the recycling of ferrous waste in the furnace, also as additive for intensifying the combustion process around the tuyeres.

  18. Iron transport, deposition and bioavailability in the wheat and barley grain

    DEFF Research Database (Denmark)

    Borg, Søren; Brinch-Pedersen, Henrik; Tauris, Birgitte

    2009-01-01

    In recent years, the increasing knowledge on the molecular mechanisms underlying mineral uptake, transport, homeostasis and deposition within plants, has paved the way for a more targeted approach to improving the nutrient status of crop plants based on biotechnology. In the present paper we...... will briefly review existing knowledge on the distribution and transport pathways of iron in the two small grained cereals, barley and wheat, and focus on the efforts made to increase the iron content in cereals in general. However, mineral content is not the only factor of relevance for improving...... insight into metal transport and deposition (Tauris et al. 2009). In the present paper we will provide a tentative and preliminary roadmap for iron trafficking in the barley grain...

  19. Transport properties of zigzag graphene nanoribbons adsorbed with single iron atom

    Institute of Scientific and Technical Information of China (English)

    杨玉娥; 肖杨; 颜晓红; 戴昌杰

    2015-01-01

    We have performed density-functional calculations of the transport properties of the zigzag graphene nanoribbon (ZGNR) adsorbed with a single iron atom. Two adsorption configurations are considered, i.e., iron adsorbed on the edge and on the interior of the nanoribbon. The results show that the transport features of the two configurations are similar. However, the transport properties are modified due to the scattering effects induced by coupling of the ZGNR band states to the localized 3d-orbital state of the iron atom. More importantly, one can find that several dips appear in the transmission curve, which is closely related to the above mentioned coupling. We expect that our results will have potential applications in graphene-based spintronic devices.

  20. Purification, crystallization and preliminary X-ray diffraction analysis of the putative ABC transporter ATP-binding protein from Thermotoga maritima

    Science.gov (United States)

    Ethayathulla, Abdul S.; Bessho, Yoshitaka; Shinkai, Akeo; Padmanabhan, Balasundaram; Singh, Tej P.; Kaur, Punit; Yokoyama, Shigeyuki

    2008-01-01

    Adenosine triphosphate (ATP) binding cassette transporters (ABC transporters) are ATP hydrolysis-dependent transmembrane transporters. Here, the overproduction, purification and crystallization of the putative ABC transporter ATP-binding protein TM0222 from Thermotoga maritima are reported. The protein was crystallized in the hexagonal space group P6422, with unit-cell parameters a = b = 148.49, c = 106.96 Å, γ = 120.0°. Assuming the presence of two molecules in the asymmetric unit, the calculated V M is 2.84 Å3 Da−1, which corresponds to a solvent content of 56.6%. A three-wavelength MAD data set was collected to 2.3 Å resolution from SeMet-substituted TM0222 crystals. Data sets were collected on the BL38B1 beamline at SPring-8, Japan. PMID:18540059

  1. ZIP8 is an iron and zinc transporter whose cell-surface expression is up-regulated by cellular iron loading.

    Science.gov (United States)

    Wang, Chia-Yu; Jenkitkasemwong, Supak; Duarte, Stephanie; Sparkman, Brian K; Shawki, Ali; Mackenzie, Bryan; Knutson, Mitchell D

    2012-10-05

    ZIP8 (SLC39A8) belongs to the ZIP family of metal-ion transporters. Among the ZIP proteins, ZIP8 is most closely related to ZIP14, which can transport iron, zinc, manganese, and cadmium. Here we investigated the iron transport ability of ZIP8, its subcellular localization, pH dependence, and regulation by iron. Transfection of HEK 293T cells with ZIP8 cDNA enhanced the uptake of (59)Fe and (65)Zn by 200 and 40%, respectively, compared with controls. Excess iron inhibited the uptake of zinc and vice versa. In RNA-injected Xenopus oocytes, ZIP8-mediated (55)Fe(2+) transport was saturable (K(0.5) of ∼0.7 μm) and inhibited by zinc. ZIP8 also mediated the uptake of (109)Cd(2+), (57)Co(2+), (65)Zn(2+) > (54)Mn(2+), but not (64)Cu (I or II). By using immunofluorescence analysis, we found that ZIP8 expressed in HEK 293T cells localized to the plasma membrane and partially in early endosomes. Iron loading increased total and cell-surface levels of ZIP8 in H4IIE rat hepatoma cells. We also determined by using site-directed mutagenesis that asparagine residues 40, 88, and 96 of rat ZIP8 are glycosylated and that N-glycosylation is not required for iron or zinc transport. Analysis of 20 different human tissues revealed abundant ZIP8 expression in lung and placenta and showed that its expression profile differs markedly from ZIP14, suggesting nonredundant functions. Suppression of endogenous ZIP8 expression in BeWo cells, a placental cell line, reduced iron uptake by ∼40%, suggesting that ZIP8 participates in placental iron transport. Collectively, these data identify ZIP8 as an iron transport protein that may function in iron metabolism.

  2. The FupA/B protein uniquely facilitates transport of ferrous iron and siderophore-associated ferric iron across the outer membrane of Francisella tularensis live vaccine strain

    Science.gov (United States)

    Sen, Bhaswati

    2014-01-01

    Francisella tularensis is a highly infectious Gram-negative pathogen that replicates intracellularly within the mammalian host. One of the factors associated with virulence of F. tularensis is the protein FupA that mediates high-affinity transport of ferrous iron across the outer membrane. Together with its paralogue FslE, a siderophore–ferric iron transporter, FupA supports survival of the pathogen in the host by providing access to the essential nutrient iron. The FupA orthologue in the attenuated live vaccine strain (LVS) is encoded by the hybrid gene fupA/B, the product of an intergenic recombination event that significantly contributes to attenuation of the strain. We used 55Fe transport assays with mutant strains complemented with the different paralogues to show that the FupA/B protein of LVS retains the capacity for high-affinity transport of ferrous iron, albeit less efficiently than FupA of virulent strain Schu S4. 55Fe transport assays using purified siderophore and siderophore-dependent growth assays on iron-limiting agar confirmed previous findings that FupA/B also contributes to siderophore-mediated ferric iron uptake. These assays further demonstrated that the LVS FslE protein is a weaker siderophore–ferric iron transporter than the orthologue from Schu S4, and may be a result of the sequence variation between the two proteins. Our results indicate that iron-uptake mechanisms in LVS differ from those in Schu S4 and that functional differences in the outer membrane iron transporters have distinct effects on growth under iron limitation. PMID:24307666

  3. Iron

    Science.gov (United States)

    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 ...

  4. Iron

    Science.gov (United States)

    ... of iron stored in the body become low, iron deficiency anemia sets in. Red blood cells become smaller and ... from the lungs throughout the body. Symptoms of iron deficiency anemia include tiredness and lack of energy, GI upset, ...

  5. Draft ASME code case on ductile cast iron for transport packaging

    Energy Technology Data Exchange (ETDEWEB)

    Saegusa, T. [Central Research Inst. of Electric Power Industry, Abiko (Japan); Arai, T. [Central Research Inst. of Electric Power Industry, Yokosuka (Japan); Hirose, M. [Nuclear Fuel Transport Co., Ltd., Tokyo (Japan); Kobayashi, T. [Nippon Chuzo, Kawasaki (Japan); Tezuka, Y. [Mitsubishi Materials Co., Tokyo (Japan); Urabe, N. [Kokan Keisoku K. K., Kawasaki (Japan); Hueggenberg, R. [GNB, Essen (Germany)

    2004-07-01

    The current Rules for Construction of ''Containment Systems for Storage and Transport Packagings of Spent Nuclear Fuel and High Level Radioactive Material and Waste'' of Division 3 in Section III of ASME Code (2001 Edition) does not include ductile cast iron in its list of materials permitted for use. The Rules specify required fracture toughness values of ferritic steel material for nominal wall thickness 5/8 to 12 inches (16 to 305 mm). New rule for ductile cast iron for transport packaging of which wall thickness is greater than 12 inches (305mm) is required.

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    Bidyottam Mittra

    2016-01-01

    Full Text Available 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.

  8. Interdependence between iron ore production and maritime transport

    Directory of Open Access Journals (Sweden)

    A. V. Todorut

    2016-10-01

    Full Text Available The maritime industry plays an important role in international trade, transporting a total of 10,1 billion tons of merchandise in 2015, representing over 80% of all global trade, with dry cargo estimated to account for over two thirds of the total seaborne trade. Bulk carriers supply the raw materials needed by the steel industry and container ships transport the steel products. Demand and supply for seaborne transport is influenced by trends in global economy and worldwide demand for commodities. The paper analyzes the most important economic determinants in the supply of metallurgical raw materials, highlighting the importance of the shipping sector.

  9. Yellow Stripe1. Expanded Roles for the Maize Iron-Phytosiderophore Transporter1

    Science.gov (United States)

    Roberts, Louis A.; Pierson, Abbey J.; Panaviene, Zivile; Walker, Elsbeth L.

    2004-01-01

    Graminaceous monocots, including most of the world's staple grains (i.e. rice, corn, and wheat) use a chelation strategy (Strategy II) for primary acquisition of iron from the soil. Strategy II plants secrete phytosiderophores (PS), compounds of the mugineic acid family that form stable Fe(III) chelates in soil. Uptake of iron-PS chelates, which occurs through specific transporters at the root surface, thus represents the primary route of iron entry into Strategy II plants. The gene Yellow stripe1 (Ys1) encodes the Fe(III)-PS transporter of maize (Zea mays). Here the physiological functions performed by maize YS1 were further defined by examining the pattern of Ys1 mRNA and protein accumulation and by defining YS1 transport specificity in detail. YS1 is able to translocate iron that is bound either by PS or by the related compound, nicotianamine; thus, the role of YS1 may be to transport either of these complexes. Ys1 expression at both the mRNA and protein levels responds rapidly to changes in iron availability but is not strongly affected by limitation of copper or zinc. Our data provide no support for the idea that YS1 is a transporter of zinc-PS, based on YS1 biochemical activity and Ys1 mRNA expression patterns in response to zinc deficiency. YS1 is capable of transporting copper-PS, but expression data suggest that the copper-PS uptake has limited significance in primary uptake of copper. PMID:15107503

  10. Green tea polyphenols require the mitochondrial iron transporter, mitoferrin, for lifespan extension in Drosophila melanogaster.

    Science.gov (United States)

    Lopez, Terry E; Pham, Hoang M; Nguyen, Benjamin V; Tahmasian, Yerazik; Ramsden, Shannon; Coskun, Volkan; Schriner, Samuel E; Jafari, Mahtab

    2016-12-01

    Green tea has been found to increase the lifespan of various experimental animal models including the fruit fly, Drosophila melanogaster. High in polyphenolic content, green tea has been shown to reduce oxidative stress in part by its ability to bind free iron, a micronutrient that is both essential for and toxic to all living organisms. Due to green tea's iron-binding properties, we questioned whether green tea acts to increase the lifespan of the fruit fly by modulating iron regulators, specifically, mitoferrin, a mitochondrial iron transporter, and transferrin, found in the hemolymph of flies. Publicly available hypomorph mutants for these iron regulators were utilized to investigate the effect of green tea on lifespan and fertility. We identified that green tea could not increase the lifespan of mitoferrin mutants but did rescue the reduced male fertility phenotype. The effect of green tea on transferrin mutant lifespan and fertility were comparable to w(1118) flies, as observed in our previous studies, in which green tea increased male fly lifespan and reduced male fertility. Expression levels in both w(1118) flies and mutant flies, supplemented with green tea, showed an upregulation of mitoferrin but not transferrin. Total body and mitochondrial iron levels were significantly reduced by green tea supplementation in w(1118) and mitoferrin mutants but not transferrin mutant flies. Our results demonstrate that green tea may act to increase the lifespan of Drosophila in part by the regulation of mitoferrin and reduction of mitochondrial iron. © 2016 Wiley Periodicals, Inc.

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

    Science.gov (United States)

    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.

  12. A putative vesicular transporter expressed in Drosophila mushroom bodies that mediates sexual behavior may define a novel neurotransmitter system

    OpenAIRE

    Brooks, Elizabeth S.; Greer, Christina L.; Romero-Calderón, Rafael; Serway, Christine N.; Grygoruk, Anna; Haimovitz, Jasmine M.; Nguyen, Bac T.; Najibi, Rod; Tabone, Christopher J.; de Belle, J. Steven; Krantz, David E.

    2011-01-01

    Storage and release of classical and amino acid neurotransmitters requires vesicular transporters. Some neurons lack known vesicular transporters, suggesting additional neurotransmitter systems remain unidentified. Insect mushroom bodies (MBs) are critical for several behaviors, including learning, but the neurotransmitters released by the intrinsic Kenyon cells (KCs) remain unknown. Likewise, KCs do not express a known vesicular transporter. We report the identification of a novel Drosophila...

  13. A putative vesicular transporter expressed in Drosophila mushroom bodies that mediates sexual behavior may define a novel neurotransmitter system

    OpenAIRE

    Brooks, Elizabeth S.; Greer, Christina L.; Romero-Calderón, Rafael; Serway, Christine N.; Grygoruk, Anna; Haimovitz, Jasmine M.; Nguyen, Bac T.; Najibi, Rod; Tabone, Christopher J.; de Belle, J. Steven; Krantz, David E.

    2011-01-01

    Storage and release of classical and amino acid neurotransmitters requires vesicular transporters. Some neurons lack known vesicular transporters, suggesting additional neurotransmitter systems remain unidentified. Insect mushroom bodies (MBs) are critical for several behaviors, including learning, but the neurotransmitters released by the intrinsic Kenyon cells (KCs) remain unknown. Likewise, KCs do not express a known vesicular transporter. We report the identification of a novel Drosophila...

  14. RirA is the iron response regulator of the rhizobactin 1021 biosynthesis and transport genes in Sinorhizobium meliloti 2011.

    Science.gov (United States)

    Viguier, Caroline; O Cuív, Páraic; Clarke, Paul; O'Connell, Michael

    2005-05-15

    The genes encoding the biosynthesis and transport of rhizobactin 1021, a siderophore produced by Sinorhizobium meliloti, are negatively regulated by iron. Mutagenesis of rirA, the rhizobial iron regulator, resulted in abolition of the iron responsive regulation of the biosynthesis and transport genes. Bioassay analysis revealed that the siderophore is produced in the presence of iron in a rirA mutant. RNA analysis and GFP fusions supported the conclusion that RirA is the mediator of iron-responsive transcriptional repression of the two transcripts encoding the biosynthesis and transport genes. RirA in S. meliloti appears to fulfil the role often observed for Fur in other bacterial species. The regulator was found to mediate the iron-responsive expression of two additional genes, smc02726 and dppA1, repressing the former while activating the latter. The rirA mutant nodulated the host plant Medicago sativa (alfalfa) and fixed nitrogen as effectively as the wild type.

  15. Change of iron species and iron solubility in Asian dust during the long-range transport from western China to Japan

    Directory of Open Access Journals (Sweden)

    Y. Takahashi

    2011-07-01

    Full Text Available In the North Pacific, transport and deposition of mineral dust from Asia appear to be one of major sources of iron which can regulate growth of phytoplankton in the ocean. In this process, it is essential to identify chemical species of iron contained in Asian dust, because bioavailability of iron in the ocean is strongly influenced by the solubility of iron, which in turn is dependent on iron species in the dust. Here, we report that clay minerals (illite and chlorite in the dusts near the source (western China are transformed into ferrihydrite by atmospheric chemical processes during their long-range transport to eastern China and Japan based on the speciation by X-ray absorption fine structure (XAFS and other methods such as X-ray diffraction and chemical extraction. Moreover, it was found that iron in the dust after the transport becomes more soluble in our leaching experiments conducted for 24 h compared with those for initial dusts possibly due to the formation of ferrihydrite in the atmosphere. Our findings suggested that ferrihydrite secondarily formed during the transport is an important source of soluble iron species, which can be more soluble than clay minerals initially contained in the mineral dust such as illite and chlorite.

  16. Maize ZmFDR3 localized in chloroplasts is involved in iron transport

    Institute of Scientific and Technical Information of China (English)

    HAN JianHui; SONG XiuFang; LI Peng; YANG HuiJun; YIN LiPing

    2009-01-01

    Iron is an essential nutrient for plant metabolism such that Fe-limited plants display chlorosis and suffer from reduced photosynthetic efficiency. Differential display previously identified genes whose expression was elevated in Fe-deficient maize roots. Here, we describe the functional characterization of one of the genes identified in the screen, ZmFDR3 (Zea maize Fe-deficiency-related). Heterologous functional complementation assays using a yeast iron uptake mutant showed that ZmFDR3 functions in iron transport. ZmFDR3 contains a domain found in FliN-proteins of the type Ⅲ secretion system and is predicted to localize to the thylakoid of plastids. Fluorescence immunocytochemistry showed that ZmFDR3 is localized in the plastids of roots, stems and leaves, with high expression found in guard cell chloroplasts. Transgenic tobacco expressing a 355-ZmFDR3 construct contains elevated iron content, displays well arranged thylakoid membranes and has photosynthetic indices that are higher than those of the wild type. Together, these results suggest that ZmFDR3 functions in chloroplast iron transport.

  17. Maize ZmFDR3 localized in chloroplasts is involved in iron transport

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Iron is an essential nutrient for plant metabolism such that Fe-limited plants display chlorosis and suffer from reduced photosynthetic efficiency. Differential display previously identified genes whose expression was elevated in Fe-deficient maize roots. Here,we describe the functional characterization of one of the genes identified in the screen,ZmFDR3 (Zea maize Fe-deficiency-related). Heterologous functional complementation assays using a yeast iron uptake mutant showed that ZmFDR3 functions in iron transport. ZmFDR3 contains a domain found in FliN-proteins of the type III secretion system and is predicted to localize to the thylakoid of plastids. Fluorescence immunocytochemistry showed that ZmFDR3 is localized in the plastids of roots,stems and leaves,with high expression found in guard cell chloroplasts. Transgenic tobacco expressing a 35S-ZmFDR3 construct contains elevated iron content,displays well arranged thylakoid membranes and has photosynthetic indices that are higher than those of the wild type. Together,these results suggest that ZmFDR3 functions in chloroplast iron transport.

  18. Change of iron species and iron solubility in Asian dust during the long-range transport from western China to Japan

    Directory of Open Access Journals (Sweden)

    Y. Takahashi

    2011-11-01

    Full Text Available In the North Pacific, transport and deposition of mineral dust from Asia appear to be one of major sources of iron which can regulate growth of phytoplankton in the ocean. In this process, it is essential to identify chemical species of iron contained in Asian dust, because bioavailability of iron in the ocean is strongly influenced by the solubility of iron, which in turn is dependent on iron species in the dust. Here, we report that clay minerals (illite and chlorite in the dusts near the source collected at Aksu (western China can be transformed into ferrihydrite by atmospheric chemical processes during their long-range transport to eastern China (Qingdao and Japan (Tsukuba based on the speciation by X-ray absorption fine structure (XAFS and other methods such as X-ray diffraction and chemical extraction. As a result, Fe molar ratio in Aksu (illite : chlorite : ferrihydrite = 70 : 25 : 5 was changed to that in Tsukuba (illite : chlorite : ferrihydrite = 65 : 10 : 25. Moreover, leaching experiments were conducted to study the change of iron solubility. It was found that the iron solubility for the dust in Tsukuba (soluble iron fraction: 11.8 % and 1.10 % for synthetic rain water and seawater, respectively was larger than that in Aksu (4.1 % and 0.28 %, respectively, showing that iron in the dust after the transport becomes more soluble possibly due to the formation of ferrihydrite in the atmosphere. Our findings suggested that secondary formation of ferrihydrite during the transport should be considered as one of important processes in evaluating the supply of soluble iron to seawater.

  19. Enhanced transport of zerovalent iron nanoparticles in saturated porous media by guar gum

    Energy Technology Data Exchange (ETDEWEB)

    Tiraferri, Alberto; Sethi, Rajandrea, E-mail: rajandrea.sethi@polito.i [Politecnico di Torino, DITAG - Dipartimento di Ingegneria del Territorio, dell' Ambiente e delle Geotecnologie (Italy)

    2009-04-15

    In order to ensure adequate mobility of zerovalent iron nanoparticles in natural aquifers, the use of a stabilizing agent is necessary. Polymers adsorbed on the nanoparticle surface will give rise to electrosteric stabilization and will decrease attachment to the surface soil grains. Water saturated sand-packed columns were used in this study to investigate the transport of iron nanoparticle suspensions, bare or modified with the green polymer guar gum. The suspensions were prepared at 154 mg/L particle concentration and 0.5 g/L polymer concentration. Transport experiments were conducted by varying the ionic strength, ionic composition, and approach velocity of the fluid. Nanoparticle deposition rates, attachment efficiencies, and travel distances were subsequently calculated based on the classical particle filtration theory. It was found that bare iron nanoparticles are basically immobile in sandy porous media. In contrast, guar gum is able to ensure significant nanoparticle transport at the tested conditions, regardless of the chemistry of the solution. Attachment efficiency values for guar gum-coated nanoparticles under the various conditions tested were smaller than 0.066. Although the calculated travel distances may not prove satisfactory for field application, the investigation attested the promising role of guar gum to ensure mobility of iron nanoparticles in the subsurface environment.

  20. Enhanced transport of zerovalent iron nanoparticles in saturated porous media by guar gum

    Science.gov (United States)

    Tiraferri, Alberto; Sethi, Rajandrea

    2009-04-01

    In order to ensure adequate mobility of zerovalent iron nanoparticles in natural aquifers, the use of a stabilizing agent is necessary. Polymers adsorbed on the nanoparticle surface will give rise to electrosteric stabilization and will decrease attachment to the surface soil grains. Water saturated sand-packed columns were used in this study to investigate the transport of iron nanoparticle suspensions, bare or modified with the green polymer guar gum. The suspensions were prepared at 154 mg/L particle concentration and 0.5 g/L polymer concentration. Transport experiments were conducted by varying the ionic strength, ionic composition, and approach velocity of the fluid. Nanoparticle deposition rates, attachment efficiencies, and travel distances were subsequently calculated based on the classical particle filtration theory. It was found that bare iron nanoparticles are basically immobile in sandy porous media. In contrast, guar gum is able to ensure significant nanoparticle transport at the tested conditions, regardless of the chemistry of the solution. Attachment efficiency values for guar gum-coated nanoparticles under the various conditions tested were smaller than 0.066. Although the calculated travel distances may not prove satisfactory for field application, the investigation attested the promising role of guar gum to ensure mobility of iron nanoparticles in the subsurface environment.

  1. Iron

    DEFF Research Database (Denmark)

    Hansen, Jakob Bondo; Moen, I W; Mandrup-Poulsen, T

    2014-01-01

    The interest in the role of ferrous iron in diabetes pathophysiology has been revived by recent evidence of iron as an important determinant of pancreatic islet inflammation and as a biomarker of diabetes risk and mortality. The iron metabolism in the β-cell is complex. Excess free iron is toxic......, but at the same time, iron is required for normal β-cell function and thereby glucose homeostasis. In the pathogenesis of diabetes, iron generates reactive oxygen species (ROS) by participating in the Fenton chemistry, which can induce oxidative damage and apoptosis. The aim of this review is to present...... and discuss recent evidence, suggesting that iron is a key pathogenic factor in both type 1 and type 2 diabetes with a focus on inflammatory pathways. Pro-inflammatory cytokine-induced β-cell death is not fully understood, but may include iron-induced ROS formation resulting in dedifferentiation by activation...

  2. A putative vesicular transporter expressed in Drosophila mushroom bodies that mediates sexual behavior may define a novel neurotransmitter system

    Science.gov (United States)

    Brooks, Elizabeth S.; Greer, Christina L.; Romero-Calderón, Rafael; Serway, Christine N.; Grygoruk, Anna; Haimovitz, Jasmine M.; Nguyen, Bac T.; Najibi, Rod; Tabone, Christopher J.; de Belle, J. Steven; Krantz, David E.

    2011-01-01

    Summary Storage and release of classical and amino acid neurotransmitters requires vesicular transporters. Some neurons lack known vesicular transporters, suggesting additional neurotransmitter systems remain unidentified. Insect mushroom bodies (MBs) are critical for several behaviors, including learning, but the neurotransmitters released by the intrinsic Kenyon cells (KCs) remain unknown. Likewise, KCs do not express a known vesicular transporter. We report the identification of a novel Drosophila gene portabella (prt) that is structurally similar to known vesicular transporters. Both larval and adult brains express PRT in the KCs of the MBs. Additional PRT cells project to the central complex and optic ganglia. prt mutation causes an olfactory learning deficit and an unusual defect in the male’s position during copulation that is rescued by expression in KCs. Since prt is expressed in neurons that lack other known vesicular transporters or neurotransmitters, it may define a previously unknown neurotransmitter system responsible for sexual behavior and a component of olfactory learning. PMID:22017990

  3. Whole-transcriptome survey of the putative ATP-binding cassette (ABC) transporter family genes in the latex-producing laticifers of Hevea brasiliensis.

    Science.gov (United States)

    Zhiyi, Nie; Guijuan, Kang; Yu, Li; Longjun, Dai; Rizhong, Zeng

    2015-01-01

    The ATP-binding cassette (ABC) proteins or transporters constitute a large protein family in plants and are involved in many different cellular functions and processes, including solute transportation, channel regulation and molecular switches, etc. Through transcriptome sequencing, a transcriptome-wide survey and expression analysis of the ABC protein genes were carried out using the laticiferous latex from Hevea brasiliensis (rubber tree). A total of 46 putative ABC family proteins were identified in the H. brasiliensis latex. These consisted of 12 'full-size', 21 'half-size' and 13 other putative ABC proteins, and all of them showed strong conservation with their Arabidopsis thaliana counterparts. This study indicated that all eight plant ABC protein paralog subfamilies were identified in the H. brasiliensis latex, of which ABCB, ABCG and ABCI were the most abundant. Real-time quantitative reverse transcription-polymerase chain reaction assays demonstrated that gene expression of several latex ABC proteins was regulated by ethylene, jasmonic acid or bark tapping (a wound stress) stimulation, and that HbABCB15, HbABCB19, HbABCD1 and HbABCG21 responded most significantly of all to the abiotic stresses. The identification and expression analysis of the latex ABC family proteins could facilitate further investigation into their physiological involvement in latex metabolism and rubber biosynthesis by H. brasiliensis.

  4. Whole-transcriptome survey of the putative ATP-binding cassette (ABC transporter family genes in the latex-producing laticifers of Hevea brasiliensis.

    Directory of Open Access Journals (Sweden)

    Nie Zhiyi

    Full Text Available The ATP-binding cassette (ABC proteins or transporters constitute a large protein family in plants and are involved in many different cellular functions and processes, including solute transportation, channel regulation and molecular switches, etc. Through transcriptome sequencing, a transcriptome-wide survey and expression analysis of the ABC protein genes were carried out using the laticiferous latex from Hevea brasiliensis (rubber tree. A total of 46 putative ABC family proteins were identified in the H. brasiliensis latex. These consisted of 12 'full-size', 21 'half-size' and 13 other putative ABC proteins, and all of them showed strong conservation with their Arabidopsis thaliana counterparts. This study indicated that all eight plant ABC protein paralog subfamilies were identified in the H. brasiliensis latex, of which ABCB, ABCG and ABCI were the most abundant. Real-time quantitative reverse transcription-polymerase chain reaction assays demonstrated that gene expression of several latex ABC proteins was regulated by ethylene, jasmonic acid or bark tapping (a wound stress stimulation, and that HbABCB15, HbABCB19, HbABCD1 and HbABCG21 responded most significantly of all to the abiotic stresses. The identification and expression analysis of the latex ABC family proteins could facilitate further investigation into their physiological involvement in latex metabolism and rubber biosynthesis by H. brasiliensis.

  5. Prion protein (PrP knock-out mice show altered iron metabolism: a functional role for PrP in iron uptake and transport.

    Directory of Open Access Journals (Sweden)

    Ajay Singh

    Full Text Available Despite overwhelming evidence implicating the prion protein (PrP in prion disease pathogenesis, the normal function of this cell surface glycoprotein remains unclear. In previous reports we demonstrated that PrP mediates cellular iron uptake and transport, and aggregation of PrP to the disease causing PrP-scrapie (PrP(Sc form results in imbalance of iron homeostasis in prion disease affected human and animal brains. Here, we show that selective deletion of PrP in transgenic mice (PrP(KO alters systemic iron homeostasis as reflected in hematological parameters and levels of total iron and iron regulatory proteins in the plasma, liver, spleen, and brain of PrP(KO mice relative to matched wild type controls. Introduction of radiolabeled iron ((59FeCl(3 to Wt and PrP(KO mice by gastric gavage reveals inefficient transport of (59Fe from the duodenum to the blood stream, an early abortive spike of erythropoiesis in the long bones and spleen, and eventual decreased (59Fe content in red blood cells and all major organs of PrP(KO mice relative to Wt controls. The iron deficient phenotype of PrP(KO mice is reversed by expressing Wt PrP in the PrP(KO background, demonstrating a functional role for PrP in iron uptake and transport. Since iron is required for essential metabolic processes and is also potentially toxic if mismanaged, these results suggest that loss of normal function of PrP due to aggregation to the PrP(Sc form induces imbalance of brain iron homeostasis, resulting in disease associated neurotoxicity.

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

    Science.gov (United States)

    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.

  7. A putative vesicular transporter expressed in Drosophila mushroom bodies that mediates sexual behavior may define a neurotransmitter system.

    Science.gov (United States)

    Brooks, Elizabeth S; Greer, Christina L; Romero-Calderón, Rafael; Serway, Christine N; Grygoruk, Anna; Haimovitz, Jasmine M; Nguyen, Bac T; Najibi, Rod; Tabone, Christopher J; de Belle, J Steven; Krantz, David E

    2011-10-20

    Vesicular transporters are required for the storage of all classical and amino acid neurotransmitters in synaptic vesicles. Some neurons lack known vesicular transporters, suggesting additional neurotransmitter systems remain unidentified. Insect mushroom bodies (MBs) are critical for several behaviors, including learning, but the neurotransmitters released by the intrinsic Kenyon cells (KCs) remain unknown. Likewise, KCs do not express a known vesicular transporter. We report the identification of a novel Drosophila gene portabella (prt) that is structurally similar to known vesicular transporters. Both larval and adult brains express PRT in the KCs of the MBs. Additional PRT cells project to the central complex and optic ganglia. prt mutation causes an olfactory learning deficit and an unusual defect in the male's position during copulation that is rescued by expression in KCs. Because prt is expressed in neurons that lack other known vesicular transporters or neurotransmitters, it may define a previously unknown neurotransmitter system responsible for sexual behavior and a component of olfactory learning. Copyright © 2011 Elsevier Inc. All rights reserved.

  8. Diversification and expression of the PIN, AUX/LAX and ABCB families of putative auxin transporters in Populus

    Directory of Open Access Journals (Sweden)

    Nicola eCarraro

    2012-02-01

    Full Text Available Intercellular transport of the plant hormone auxin is mediated by three families of membrane-bound protein carriers, with the PIN and ABCB families coding primarily for efflux proteins and the AUX/LAX family coding for influx proteins. In the last decade our understanding of gene and protein function for these transporters in Arabidopsis has expanded rapidly but very little is known about their role in woody plant development. Here we present a comprehensive account of all three families in the model woody species Populus, including chromosome distribution, protein structure, quantitative gene expression, and evolutionary relationships. The PIN and AUX/LAX gene families in Populus comprise 16 and 8 members respectively, and show evidence for the retention of paralogs following a relatively recent whole genome duplication. There is also evidence for differential expression across tissues within many gene pairs. The ABCB family is previously undescribed in Populus and includes 20 members, showing a much deeper evolutionary history including both tandem and whole genome duplication as well as probable loss. A striking number of these transporters are expressed in developing Populus stems and we suggest that evolutionary and structural relationships with known auxin transporters in Arabidopsis can point toward candidate genes for further study in Populus. This is especially important for the ABCBs, which is a large family and includes members in Arabidopsis that are able to transport other substrates in addition to auxin. Protein modeling, sequence alignment and expression data all point to ABCB1.1 as a likely auxin transport protein in Populus. Given that basipetal auxin flow through the cambial zone shapes the development of woody stems, it is important that we identify the full complement of proteins involved in this process. This work should lay the foundation for studies targeting specific proteins for functional characterization and in situ

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

    Science.gov (United States)

    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...

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

    NARCIS (Netherlands)

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

    2013-01-01

    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

  11. High-Throughput Screening Assay for Inhibitors of TonB-Dependent Iron Transport.

    Science.gov (United States)

    Hanson, Mathew; Jordan, Lorne D; Shipelskiy, Yan; Newton, Salete M; Klebba, Phillip E

    2016-03-01

    The TonB-dependent Gram-negative bacterial outer membrane protein FepA actively transports the siderophore ferric enterobactin (FeEnt) into the periplasm. We developed a high-throughput screening (HTS) assay that observes FeEnt uptake through FepA in living Escherichia coli, by monitoring fluorescence quenching that occurs upon binding of FeEnt, and then unquenching as the bacteria deplete it from solution by transport. We optimized the labeling and spectroscopic methods to screen for inhibitors of TonB-dependent iron uptake through the outer membrane. The assay works like a molecular switch that is on in the presence of TonB activity and off in its absence. It functions in 96-well microtiter plates, in a variety of conditions, with Z factors of 0.8-1.0. TonB-dependent iron transport is energy dependent, and the inhibitory effects of the metabolic inhibitors carbonyl cyanide m-chlorophenylhydrazone, 2,4-dinitrophenol, azide, cyanide, and arsenate on FeEnt uptake were readily detected by the assay. Because iron acquisition is a determinant of bacterial pathogenesis, HTS with this method may identify inhibitors that block TonB function and constitute novel therapeutics against infectious disease caused by Gram-negative bacteria. © 2015 Society for Laboratory Automation and Screening.

  12. Transport coefficients and entropy-scaling law in liquid iron up to Earth-core pressures.

    Science.gov (United States)

    Cao, Qi-Long; Wang, Pan-Pan; Huang, Duo-Hui; Yang, Jun-Sheng; Wan, Ming-Jie; Wang, Fan-Hou

    2014-03-21

    Molecular dynamics simulations were applied to study the structural and transport properties, including the pair distribution function, the structure factor, the pair correlation entropy, self-diffusion coefficient, and viscosity, of liquid iron under high temperature and high pressure conditions. Our calculated results reproduced experimentally determined structure factors of liquid iron, and the calculated self-diffusion coefficients and viscosity agree well with previous simulation results. We show that there is a moderate increase of self-diffusion coefficients and viscosity along the melting curve up to the Earth-core pressure. Furthermore, the temperature dependencies of the pair correlation entropy, self-diffusion, and viscosity under high pressure condition have been investigated. Our results suggest that the temperature dependence of the pair correlation entropy is well described by T(-1) scaling, while the Arrhenius law well describes the temperature dependencies of self-diffusion coefficients and viscosity under high pressure. In particular, we find that the entropy-scaling laws, proposed by Rosenfeld [Phys. Rev. A 15, 2545 (1977)] and Dzugutov [Nature (London) 381, 137 (1996)] for self-diffusion coefficients and viscosity in liquid metals under ambient pressure, still hold well for liquid iron under high temperature and high pressure conditions. Using the entropy-scaling laws, we can obtain transport properties from structural properties under high pressure and high temperature conditions. The results provide a useful ingredient in understanding transport properties of planet's cores.

  13. A putative transport protein is involved in citrulline excretion and re-uptake during arginine deiminase pathway activity by Lactobacillus sakei.

    Science.gov (United States)

    Rimaux, Tom; Rivière, Audrey; Hebert, Elvira María; Mozzi, Fernanda; Weckx, Stefan; De Vuyst, Luc; Leroy, Frédéric

    2013-04-01

    Arginine conversion through the arginine deiminase (ADI) pathway is a common metabolic trait of Lactobacillus sakei which is ascribed to an arc operon and which inquisitively involves citrulline excretion and re-uptake. The aim of this study was to verify whether a putative transport protein (encoded by the PTP gene) plays a role in citrulline-into-ornithine conversion by L. sakei strains. This was achieved through a combination of fermentation experiments, gene expression analysis via quantitative real-time reverse transcription PCR (RT-qPCR) and construction of a PTP knock-out mutant. Expression of the PTP gene was modulated by environmental pH and was highest in the end-exponential or mid-exponential growth phase for L. sakei strains CTC 494 and 23K, respectively. In contrast to known genes of the arc operon, the PTP gene showed low expression at pH 7.0, in agreement with the finding that citrulline-into-ornithine conversion is inhibited at this pH. The presence of additional energy sources also influenced ADI pathway activity, in particular by decreasing citrulline-into-ornithine conversion. Further insight into the functionality of the PTP gene was obtained with a knock-out mutant of L. sakei CTC 494 impaired in the PTP gene, which displayed inhibition in its ability to convert extracellular citrulline into ornithine. In conclusion, results indicated that the PTP gene may putatively encode a citrulline/ornithine antiporter.

  14. The Arabidopsis MTP8 transporter determines the localization of manganese and iron in seeds.

    Science.gov (United States)

    Chu, Heng-Hsuan; Car, Suzana; Socha, Amanda L; Hindt, Maria N; Punshon, Tracy; Guerinot, Mary Lou

    2017-09-08

    Understanding how seeds obtain and store nutrients is key to developing crops with higher agronomic and nutritional value. We have uncovered unique patterns of micronutrient localization in seeds using synchrotron X-ray fluorescence (SXRF). Although all four members of the Arabidopsis thaliana Mn-CDF family can transport Mn, here we show that only mtp8-2 has an altered Mn distribution pattern in seeds. In an mtp8-2 mutant, Mn no longer accumulates in hypocotyl cortex cells and sub-epidermal cells of the embryonic cotyledons, but rather accumulates with Fe in the cells surrounding the vasculature, a pattern previously shown to be determined by the vacuolar transporter VIT1. We also show that MTP8, unlike the other three Mn-CDF family members, can transport Fe and is responsible for localization of Fe to the same cells that store Mn. When both the VIT1 and MTP8 transporters are non-functional, there is no accumulation of Fe or Mn in specific cell types; rather these elements are distributed amongst all cell types in the seed. Disruption of the putative Fe binding sites in MTP8 resulted in loss of ability to transport Fe but did not affect the ability to transport Mn.

  15. CFP, the putative cercosporin transporter of Cercospora kikuchii, is required for wild type cercosporin production, resistance, and virulence on soybean.

    Science.gov (United States)

    Callahan, T M; Rose, M S; Meade, M J; Ehrenshaft, M; Upchurch, R G

    1999-10-01

    Many species of the fungal genus Cercospora, including the soybean pathogen C. kikuchii, produce the phytotoxic polyketide cercosporin. Cercosporin production is induced by light. Previously, we identified several cDNA clones of mRNA transcripts that exhibited light-enhanced accumulation in C. kikuchii. Targeted disruption of the genomic copy of one of these, now designated CFP (cercosporin facilitator protein), results in a drastic reduction in cercosporin production, greatly reduced virulence of the fungus to soybean, and increased sensitivity to exogenous cercosporin. Sequence analysis of CFP reveals an 1,821-bp open reading frame encoding a 65.4-kDa protein similar to several members of the major facilitator superfamily (MFS) of integral membrane transporter proteins known to confer resistance to various antibiotics and toxins in fungi and bacteria. We propose that CFP encodes a cercosporin transporter that contributes resistance to cercosporin by actively exporting cercosporin, thus maintaining low cellular concentrations of the toxin.

  16. A putative cell surface receptor for white spot syndrome virus is a member of a transporter superfamily.

    Directory of Open Access Journals (Sweden)

    Huai-Ting Huang

    Full Text Available White spot syndrome virus (WSSV, a large enveloped DNA virus, can cause the most serious viral disease in shrimp and has a wide host range among crustaceans. In this study, we identified a surface protein, named glucose transporter 1 (Glut1, which could also interact with WSSV envelope protein, VP53A. Sequence analysis revealed that Glut1 is a member of a large superfamily of transporters and that it is most closely related to evolutionary branches of this superfamily, branches that function to transport this sugar. Tissue tropism analysis showed that Glut1 was constitutive and highly expressed in almost all organs. Glut1's localization in shrimp cells was further verified and so was its interaction with Penaeus monodon chitin-binding protein (PmCBP, which was itself identified to interact with an envelope protein complex formed by 11 WSSV envelope proteins. In vitro and in vivo neutralization experiments using synthetic peptide contained WSSV binding domain (WBD showed that the WBD peptide could inhibit WSSV infection in primary cultured hemocytes and delay the mortality in shrimps challenged with WSSV. These findings have important implications for our understanding of WSSV entry.

  17. Volume regulation of intestinal cells of echinoderms: Putative role of ion transporters (Na(+)/K(+)-ATPase and NKCC).

    Science.gov (United States)

    Castellano, Giovanna C; Souza, Marta M; Freire, Carolina A

    2016-11-01

    Echinoderms are exclusively marine osmoconformer invertebrates. Some species occupy the challenging intertidal region. Upon salinity changes, the extracellular osmotic concentration of these animals also varies, exposing tissues and cells to osmotic challenges. Cells and tissues may then respond with volume regulation mechanisms, which involve transport of ions and water into and/or out of the cells, through ion transporters, such as the Na(+)/K(+)-ATPase and NKCC. The goal of this study was to relate the cell volume regulation capacity of echinoderm intestinal cells Na(+)/K(+)-ATPase and NKCC activities, in three echinoderm species: Holothuria grisea, Arbacia lixula, and Echinometra lucunter. Isolated cells of these species displayed some control of their cell volume upon exposure to anisosmotic media (isolated intestinal cells, calcein fluorescence as indicator of volume change), with a distinct higher capacity shown by H. grisea, which did not swell even upon 50% hyposmotic shock. The holothuroid cells showed indirect evidence (effect of furosemide) of the participation of NKCC in this process, with a secretory function, and of a secondary role by the NKA (effect of ouabain). Other mechanisms are probably responsible for this function in the urchins. Variable expression of these transporters, and others not examined here, may to some extent account for the variability in cell volume regulation capacity in echinoderm cells.

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

    Science.gov (United States)

    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.

  19. Effects of the putative neutrophil-generated toxin, hypochlorous acid, on membrane permeability and transport systems of Escherichia coli.

    Science.gov (United States)

    Albrich, J M; Gilbaugh, J H; Callahan, K B; Hurst, J K

    1986-01-01

    Titrimetric addition of hypochlorous acid (HOCl) or chloramine (NH2Cl) to suspensions of Escherichia coli decreases their ability to accumulate 14C-labeled glutamine, proline, thiomethylgalactoside, and leucine in a manner that approximately coincides with loss of cell viability; quantitative differences in cellular response are observed with the two oxidants. Inhibition of beta-galactosidase activity in E. coli ML-35, a strain lacking functional lactose permease, is complex and also depends upon the identity of the oxidant. Membrane proton conductivities and glycerol permeabilities are unchanged by addition of HOCl or NH2Cl in excess of that required for inactivation. The combined results are interpreted to indicate that the locus of HOCl attack is the cell envelope, that HOCl inactivation does not occur by loss of membrane structural integrity, that loss of transport function can be identified with either selective oxidative inhibition of the transport proteins or loss of cellular metabolic energy, and that different mechanisms of inactivation may exist for HOCl and NH2Cl. PMID:3013936

  20. A novel transport mechanism for MOMP in Chlamydophila pneumoniae and its putative role in immune-therapy.

    Directory of Open Access Journals (Sweden)

    Francis O Atanu

    Full Text Available Major outer membrane proteins (MOMPs of Gram negative bacteria are one of the most intensively studied membrane proteins. MOMPs are essential for maintaining the structural integrity of bacterial outer membranes and in adaptation of parasites to their hosts. There is evidence to suggest a role for purified MOMP from Chlamydophila pneumoniae and corresponding MOMP-derived peptides in immune-modulation, leading to a reduced atherosclerotic phenotype in apoE(-/- mice via a characteristic dampening of MHC class II activity. The work reported herein tests this hypothesis by employing a combination of homology modelling and docking to examine the detailed molecular interactions that may be responsible. A three-dimensional homology model of the C. pneumoniae MOMP was constructed based on the 14 transmembrane β-barrel crystal structure of the fatty acid transporter from Escherichia coli, which provides a plausible transport mechanism for MOMP. Ligand docking experiments were used to provide details of the possible molecular interactions driving the binding of MOMP-derived peptides to MHC class II alleles known to be strongly associated with inflammation. The docking experiments were corroborated by predictions from conventional immuno-informatic algorithms. This work supports further the use of MOMP in C. pneumoniae as a possible vaccine target and the role of MOMP-derived peptides as vaccine candidates for immune-therapy in chronic inflammation that can result in cardiovascular events.

  1. A novel transport mechanism for MOMP in Chlamydophila pneumoniae and its putative role in immune-therapy.

    Science.gov (United States)

    Atanu, Francis O; Oviedo-Orta, Ernesto; Watson, Kimberly A

    2013-01-01

    Major outer membrane proteins (MOMPs) of Gram negative bacteria are one of the most intensively studied membrane proteins. MOMPs are essential for maintaining the structural integrity of bacterial outer membranes and in adaptation of parasites to their hosts. There is evidence to suggest a role for purified MOMP from Chlamydophila pneumoniae and corresponding MOMP-derived peptides in immune-modulation, leading to a reduced atherosclerotic phenotype in apoE(-/-) mice via a characteristic dampening of MHC class II activity. The work reported herein tests this hypothesis by employing a combination of homology modelling and docking to examine the detailed molecular interactions that may be responsible. A three-dimensional homology model of the C. pneumoniae MOMP was constructed based on the 14 transmembrane β-barrel crystal structure of the fatty acid transporter from Escherichia coli, which provides a plausible transport mechanism for MOMP. Ligand docking experiments were used to provide details of the possible molecular interactions driving the binding of MOMP-derived peptides to MHC class II alleles known to be strongly associated with inflammation. The docking experiments were corroborated by predictions from conventional immuno-informatic algorithms. This work supports further the use of MOMP in C. pneumoniae as a possible vaccine target and the role of MOMP-derived peptides as vaccine candidates for immune-therapy in chronic inflammation that can result in cardiovascular events.

  2. Transcriptome Analysis to Identify the Putative Biosynthesis and Transport Genes Associated with the Medicinal Components of Achyranthes bidentata Bl.

    Directory of Open Access Journals (Sweden)

    Jinting Li

    2016-12-01

    Full Text Available Achyranthes bidentata is a popular perennial medicine herb used for thousands of years in China to treat various diseases. Although this herb has multiple pharmaceutical purposes in China, no transcriptomic information has been reported for this species. In addition, the understanding of several key pathways and enzymes involved in the biosynthesis of oleanolic acid and ecdysterone, two pharmacologically active classes of metabolites and major chemical constituents of A. bidentata root extracts, is limited. The aim of the present study was to characterize the transcriptome profile of the roots and leaves of A. bidentata to uncover the biosynthetic and transport mechanisms of the active components. In this study, we identified 100,987 transcripts, with an average length of 973.64 base pairs. A total of 31,634 (31.33% unigenes were annotated, and 12,762 unigenes were mapped to 303 pathways according to the Kyoto Encyclopedia of Genes and Genomes (KEGG pathway database. Moreover, we identified a total of 260 oleanolic acid and ecdysterone genes encoding biosynthetic enzymes. Furthermore, the key enzymes involved in the oleanolic acid and ecdysterone synthesis pathways were analyzed using quantitative real-time polymerase chain reaction (qRT-PCR, revealing that the roots expressed these enzymes to a greater extent than the leaves. In addition, we identified 85 ATP-binding cassette (ABC transporters, some of which might be involved in the translocation of secondary metabolites.

  3. The chloroplast permease PIC1 regulates plant growth and development by directing homeostasis and transport of iron.

    Science.gov (United States)

    Duy, Daniela; Stübe, Roland; Wanner, Gerhard; Philippar, Katrin

    2011-04-01

    The membrane-spanning protein PIC1 (for permease in chloroplasts 1) in Arabidopsis (Arabidopsis thaliana) was previously described to mediate iron transport across the inner envelope membrane of chloroplasts. The albino phenotype of pic1 knockout mutants was reminiscent of iron-deficiency symptoms and characterized by severely impaired plastid development and plant growth. In addition, plants lacking PIC1 showed a striking increase in chloroplast ferritin clusters, which function in protection from oxidative stress by sequestering highly reactive free iron in their spherical protein shell. In contrast, PIC1-overexpressing lines (PIC1ox) in this study rather resembled ferritin loss-of-function plants. PIC1ox plants suffered from oxidative stress and leaf chlorosis, most likely originating from iron overload in chloroplasts. Later during growth, plants were characterized by reduced biomass as well as severely defective flower and seed development. As a result of PIC1 protein increase in the inner envelope membrane of plastids, flower tissue showed elevated levels of iron, while the content of other transition metals (copper, zinc, manganese) remained unchanged. Seeds, however, specifically revealed iron deficiency, suggesting that PIC1 overexpression sequestered iron in flower plastids, thereby becoming unavailable for seed iron loading. In addition, expression of genes associated with metal transport and homeostasis as well as photosynthesis was deregulated in PIC1ox plants. Thus, PIC1 function in plastid iron transport is closely linked to ferritin and plastid iron homeostasis. In consequence, PIC1 is crucial for balancing plant iron metabolism in general, thereby regulating plant growth and in particular fruit development.

  4. Transport properties of iron-porphyrin molecule sandwiched between Au surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Kondo, Hisashi [Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505 (Japan); CMSC, National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan)], E-mail: KONDO.Hisashi@nims.go.jp; Kino, Hiori; Nara, Jun [CMSC, National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Ohno, Takahisa [Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505 (Japan); CMSC, National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); MANA, National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan)

    2008-09-30

    The transport properties of an iron-porphyrin molecule sandwiched between Au(1 1 1) electrodes are investigated using the non-equilibrium Green's function method based on the density functional theory, and in particular, the dependence on a terminal-atom position is studied. We consider four models for terminal-atom positions. It is found that the transport properties of the junction system are very sensitive to a terminal-atom position. We also find that the contribution of the d-orbitals of the Fe atom to the transport properties around the Fermi energy strongly changes, depending on a terminal-atom position. From these results, we propose a suitable terminal-atom position for the molecular sensor discussed in the other paper.

  5. Transport of Lactate-modified Nanoscale Iron Particles in Porous Media

    Science.gov (United States)

    Reddy, K. R.

    2012-12-01

    Nanoscale iron particles (NIP) have recently shown to be effective for dehalogenation of recalcitrant organic contaminants such as pentachlorphenol (PCP) and dinitrotoluene (DNT) in the environment. However, effective transport of NIP into the contaminated subsurface zones is crucial for the success of in-situ remediation. Previous studies showed that the transport of NIP in soils is very limited and surface-modification of NIP is required to achieve adequate transport. This paper investigates the transport of NIP and lactate-modified NIP (LMNIP) through four different porous media (sands with different particle size and distribution). A series of laboratory column experiments was conducted to quantify the transport of NIP and LMNIP at two different slurry concentrations of 1 g/L and 4 g/L under two different flow velcoities. NIP used in this study possessed magentic properties, thus a magnetic susceptibility sensor system was used to monitor the changes in magnetic susceptibility (MS) along the length of the column at different times during the experiments. At the end of testing, the distribution of total Fe in the sand column was measured. Results showed a linear correlation between the Fe concentration and MS and it was used to assess the transient transport of NIP and LMNIP in the sand columns. Results showed that LMNIP transported better than bare NIP and higher concentration of 4 g/L LMNIP exhibited unform and greater transport compared to other tested conditions. Transport of NIP increased in the order from fine Ottawa sand > medium field sand > coarse field sand > coarse Ottawa sand. Filtration theory and advective-dispersion equation with reaction were applied to capture the transport response of NIP and LMNIP in the sand columns.

  6. Iron Transport through Ferroportin Is Induced by Intracellular Ascorbate and Involves IRP2 and HIF2α

    Directory of Open Access Journals (Sweden)

    Nathalie Scheers

    2014-01-01

    Full Text Available A few tightly regulated transport proteins mediate iron absorption across the intestinal epithelium. At the basolateral border of intestinal cells there is one identified transporter, ferroportin, for the transfer of intracellular iron to the vascular system. Here, we investigate the effects of ascorbate (vitamin C on the regulation of ferroportin in human intestinal Caco-2 cells using ELISA and Western Blot analyses. The results indicate that ferroportin protein levels peak at 100 μM of added ascorbate with an increase of 274% (p = 0.02. At 150 μM of ascorbate, the increase was only 28% (p = 0.04, and at 200 μM there was no significant change from the baseline control. In addition, the ascorbate-induced, (at 150 μM up-regulated ferroportin levels were associated with increased 55Fe transport across the basolateral border (19%, p = 0.03. Ascorbate-induced up-regulation of cellular ferroportin levels (no added iron was associated with increased levels of the iron regulatory protein IRP2 (230%, p = 0.0009, and the hypoxia-inducible factor HIF2α (69%, p = 0.03. Thus, iron transport across the basal border via ferroportin is influenced by the intracellular status of ascorbate and IRP2 and HIF2α are involved. We discuss possible reasons for the ascorbate-effects and the dependence of cellular growth conditions for iron transport-related protein expression.

  7. Iron transport through ferroportin is induced by intracellular ascorbate and involves IRP2 and HIF2α.

    Science.gov (United States)

    Scheers, Nathalie; Sandberg, Ann-Sofie

    2014-01-03

    A few tightly regulated transport proteins mediate iron absorption across the intestinal epithelium. At the basolateral border of intestinal cells there is one identified transporter, ferroportin, for the transfer of intracellular iron to the vascular system. Here, we investigate the effects of ascorbate (vitamin C) on the regulation of ferroportin in human intestinal Caco-2 cells using ELISA and Western Blot analyses. The results indicate that ferroportin protein levels peak at 100 μM of added ascorbate with an increase of 274% (p=0.02). At 150 μM of ascorbate, the increase was only 28% (p=0.04), and at 200 μM there was no significant change from the baseline control. In addition, the ascorbate-induced, (at 150 μM) up-regulated ferroportin levels were associated with increased 55Fe transport across the basolateral border (19%, p=0.03). Ascorbate-induced up-regulation of cellular ferroportin levels (no added iron) was associated with increased levels of the iron regulatory protein IRP2 (230%, p=0.0009), and the hypoxia-inducible factor HIF2α (69%, p=0.03). Thus, iron transport across the basal border via ferroportin is influenced by the intracellular status of ascorbate and IRP2 and HIF2α are involved. We discuss possible reasons for the ascorbate-effects and the dependence of cellular growth conditions for iron transport-related protein expression.

  8. Iron Homeostasis and Nutritional Iron Deficiency123

    OpenAIRE

    2011-01-01

    Nonheme food ferritin (FTN) iron minerals, nonheme iron complexes, and heme iron contribute to the balance between food iron absorption and body iron homeostasis. Iron absorption depends on membrane transporter proteins DMT1, PCP/HCP1, ferroportin (FPN), TRF2, and matriptase 2. Mutations in DMT1 and matriptase-2 cause iron deficiency; mutations in FPN, HFE, and TRF2 cause iron excess. Intracellular iron homeostasis depends on coordinated regulation of iron trafficking and storage proteins enc...

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

    Directory of Open Access Journals (Sweden)

    Muhammad Saleem

    Full Text Available 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.

  10. Transport of Oil-in-Water Emulsions Designed to Deliver Reactive Iron Particles in Porous Media

    Science.gov (United States)

    Crocker, J. J.; Berge, N. D.; Ramsburg, C. A.

    2007-05-01

    Treatment of subsurface regions contaminated with DNAPL is a significant challenge to environmental restoration. The focus of remediation has recently shifted from technologies that recover the contamination to technologies that destroy the contamination in situ. One method of in situ contaminant destruction employs nano- or submicron-size particles of reactive iron metal. Application of iron-based destruction technologies is currently limited by poor delivery of the reactive particles (i.e., lack of contact between the iron particles and the DNAPL). Encapsulation of the reactive particles within an oil-in-water emulsion is a novel approach that may facilitate delivery. The goal of this project was to investigate the transport behavior of emulsions (Tallow oil, Tween 80, and Span 80) within porous media. One-dimensional column experiments were conducted to evaluate pore-clogging when emulsions containing encapsulated reactive particles were passed through two homogeneous sands with an order of magnitude difference in intrinsic permeability. In these experiments, passing an emulsion through the sand column (4.8 cm i.d.) at a constant flow rate (0.86 mL/min) increased the hydraulic gradient by a factor of approximately three. The hydraulic gradient in each experiment was observed to stabilize after one pore volume of emulsion. Subsequent flushing with water recovered the initial hydraulic gradient. Together, these observations indicate that conductivity reductions during emulsion flushing were the result of viscosity and not the result of extensive pore-clogging. Analysis of effluent samples confirmed that there was minimal retention of the emulsion within the sand column. Results from these experiments suggest that emulsion encapsulation may be an effective means for transporting reactive iron particles within the subsurface environment.

  11. The Role of the Iron Transporter ABCB7 in Refractory Anemia with Ring Sideroblasts

    Science.gov (United States)

    Nikpour, Maryam; Pushkaran, Beena; Fidler, Carrie; Cattan, Helen; Littlewood, Tim J.; Malcovati, Luca; Della Porta, Matteo G.; Jädersten, Martin; Killick, Sally; Giagounidis, Aristoteles; Bowen, David; Hellström-Lindberg, Eva; Cazzola, Mario; Wainscoat, James S.

    2008-01-01

    Refractory Anemia with Ring Sideroblasts (RARS) is an acquired myelodysplastic syndrome (MDS) characterized by an excess iron accumulation in the mitochondria of erythroblasts. The pathogenesis of RARS and the cause of this unusual pattern of iron deposition remain unknown. We considered that the inherited X-linked sideroblastic anemia with ataxia (XLSA/A) might be informative for the acquired disorder, RARS. XLSA/A is caused by partial inactivating mutations of the ABCB7 ATP-binding cassette transporter gene, which functions to enable transport of iron from the mitochondria to the cytoplasm. Furthermore, ABCB7 gene silencing in HeLa cells causes an accumulation of iron in the mitochondria. We have studied the role of ABCB7 in RARS by DNA sequencing, methylation studies, and gene expression studies in primary CD34+ cells and in cultured erythroblasts. The DNA sequence of the ABCB7 gene is normal in patients with RARS. We have investigated ABCB7 gene expression levels in the CD34+ cells of 122 MDS cases, comprising 35 patients with refractory anemia (RA), 33 patients with RARS and 54 patients with RA with excess blasts (RAEB), and in the CD34+ cells of 16 healthy controls. We found that the expression levels of ABCB7 are significantly lower in the RARS group. RARS is thus characterized by lower levels of ABCB7 gene expression in comparison to other MDS subtypes. Moreover, we find a strong relationship between increasing percentage of bone marrow ring sideroblasts and decreasing ABCB7 gene expression levels. Erythroblast cell cultures confirm the low levels of ABCB7 gene expression levels in RARS. These data provide an important link between inherited and acquired forms of sideroblastic anemia and indicate that ABCB7 is a strong candidate gene for RARS. PMID:18398482

  12. The role of the iron transporter ABCB7 in refractory anemia with ring sideroblasts.

    Directory of Open Access Journals (Sweden)

    Jacqueline Boultwood

    Full Text Available Refractory Anemia with Ring Sideroblasts (RARS is an acquired myelodysplastic syndrome (MDS characterized by an excess iron accumulation in the mitochondria of erythroblasts. The pathogenesis of RARS and the cause of this unusual pattern of iron deposition remain unknown. We considered that the inherited X-linked sideroblastic anemia with ataxia (XLSA/A might be informative for the acquired disorder, RARS. XLSA/A is caused by partial inactivating mutations of the ABCB7 ATP-binding cassette transporter gene, which functions to enable transport of iron from the mitochondria to the cytoplasm. Furthermore, ABCB7 gene silencing in HeLa cells causes an accumulation of iron in the mitochondria. We have studied the role of ABCB7 in RARS by DNA sequencing, methylation studies, and gene expression studies in primary CD34(+ cells and in cultured erythroblasts. The DNA sequence of the ABCB7 gene is normal in patients with RARS. We have investigated ABCB7 gene expression levels in the CD34(+ cells of 122 MDS cases, comprising 35 patients with refractory anemia (RA, 33 patients with RARS and 54 patients with RA with excess blasts (RAEB, and in the CD34(+ cells of 16 healthy controls. We found that the expression levels of ABCB7 are significantly lower in the RARS group. RARS is thus characterized by lower levels of ABCB7 gene expression in comparison to other MDS subtypes. Moreover, we find a strong relationship between increasing percentage of bone marrow ring sideroblasts and decreasing ABCB7 gene expression levels. Erythroblast cell cultures confirm the low levels of ABCB7 gene expression levels in RARS. These data provide an important link between inherited and acquired forms of sideroblastic anemia and indicate that ABCB7 is a strong candidate gene for RARS.

  13. A vacuolar iron transporter in tulip, TgVit1, is responsible for blue coloration in petal cells through iron accumulation.

    Science.gov (United States)

    Momonoi, Kazumi; Yoshida, Kumi; Mano, Shoji; Takahashi, Hideyuki; Nakamori, Chihiro; Shoji, Kazuaki; Nitta, Akira; Nishimura, Mikio

    2009-08-01

    Blue color in flowers is due mainly to anthocyanins, and a considerable part of blue coloration can be attributed to metal-complexed anthocyanins. However, the mechanism of metal ion transport into vacuoles and subsequent flower color development has yet to be fully explored. Previously, we studied the mechanism of blue color development specifically at the bottom of the inner perianth in purple tulip petals of Tulipa gesneriana cv. Murasakizuisho. We found that differences in iron content were associated with the development of blue- and purple-colored cells. Here, we identify a vacuolar iron transporter in T. gesneriana (TgVit1), and characterize the localization and function of this transporter protein in tulip petals. The amino acid sequence of TgVit1 is 85% similar that of the Arabidopsis thaliana vacuolar iron transporter AtVIT1, and also showed similarity to the AtVIT1 homolog in yeast, Ca(2+)-sensitive cross-complementer 1 (CCC1). The gene TgVit1 was expressed exclusively in blue-colored epidermal cells, and protein levels increased with increasing mRNA expression and blue coloration. Transient expression experiments revealed that TgVit1 localizes to the vacuolar membrane, and is responsible for the development of the blue color in purple cells. Expression of TgVit1 in yeast rescued the growth defect of ccc1 mutant cells in the presence of high concentrations of FeSO(4). Our results indicate that TgVit1 plays an essential role in blue coloration as a vacuolar iron transporter in tulip petals. These results suggest a new role for involvement of a vacuolar iron transporter in blue flower color development.

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

    Science.gov (United States)

    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

  15. CgOpt1, a putative oligopeptide transporter from Colletotrichum gloeosporioides that is involved in responses to auxin and pathogenicity

    Directory of Open Access Journals (Sweden)

    Maor Rudy

    2009-08-01

    Full Text Available Abstract Background The fungus Colletotrichum gloeosporioides f. sp. aeschynomene produces high levels of indole-3-acetic acid (IAA in axenic cultures and during plant infection. We generated a suppression subtractive hybridization library enriched for IAA-induced genes and identified a clone, which was highly expressed in IAA-containing medium. Results The corresponding gene showed similarity to oligopeptide transporters of the OPT family and was therefore named CgOPT1. Expression of CgOPT1 in mycelia was low, and was enhanced by external application of IAA. cgopt1-silenced mutants produced less spores, had reduced pigmentation, and were less pathogenic to plants than the wild-type strain. IAA enhanced spore formation and caused changes in colony morphology in the wild-type strain, but had no effect on spore formation or colony morphology of the cgopt1-silenced mutants. Conclusion Our results show that IAA induces developmental changes in C. gloeosporioides. These changes are blocked in cgopt1-silenced mutants, suggesting that this protein is involved in regulation of fungal response to IAA. CgOPT1 is also necessary for full virulence, but it is unclear whether this phenotype is related to auxin.

  16. Transcriptome Analysis of Methyl Jasmonate-Elicited Panax ginseng Adventitious Roots to Discover Putative Ginsenoside Biosynthesis and Transport Genes

    Science.gov (United States)

    Cao, Hongzhe; Nuruzzaman, Mohammed; Xiu, Hao; Huang, Jingjia; Wu, Kunlu; Chen, Xianghui; Li, Jijia; Wang, Li; Jeong, Ji-Hak; Park, Sun-Jin; Yang, Fang; Luo, Junli; Luo, Zhiyong

    2015-01-01

    The Panax ginseng C.A. Meyer belonging to the Araliaceae has long been used as an herbal medicine. Although public databases are presently available for this family, no methyl jasmonate (MeJA) elicited transcriptomic information was previously reported on this species, with the exception of a few expressed sequence tags (ESTs) using the traditional Sanger method. Here, approximately 53 million clean reads of adventitious root transcriptome were separately filtered via Illumina HiSeq™2000 from two samples treated with MeJA (Pg-MeJA) and equal volumes of solvent, ethanol (Pg-Con). Jointly, a total of 71,095 all-unigenes from both samples were assembled and annotated, and based on sequence similarity search with known proteins, a total of 56,668 unigenes was obtained. Out of these annotated unigenes, 54,920 were assigned to the NCBI non-redundant protein (Nr) database, 35,448 to the Swiss-prot database, 43,051 to gene ontology (GO), and 19,986 to clusters of orthologous groups (COG). Searching in the Kyoto encyclopedia of genes and genomes (KEGG) pathway database indicated that 32,200 unigenes were mapped to 128 KEGG pathways. Moreover, we obtained several genes showing a wide range of expression levels. We also identified a total of 749 ginsenoside biosynthetic enzyme genes and 12 promising pleiotropic drug resistance (PDR) genes related to ginsenoside transport. PMID:25642758

  17. Transcriptome Analysis of Methyl Jasmonate-Elicited Panax ginseng Adventitious Roots to Discover Putative Ginsenoside Biosynthesis and Transport Genes

    Directory of Open Access Journals (Sweden)

    Hongzhe Cao

    2015-01-01

    Full Text Available The Panax ginseng C.A. Meyer belonging to the Araliaceae has long been used as an herbal medicine. Although public databases are presently available for this family, no methyl jasmonate (MeJA elicited transcriptomic information was previously reported on this species, with the exception of a few expressed sequence tags (ESTs using the traditional Sanger method. Here, approximately 53 million clean reads of adventitious root transcriptome were separately filtered via Illumina HiSeq™2000 from two samples treated with MeJA (Pg-MeJA and equal volumes of solvent, ethanol (Pg-Con. Jointly, a total of 71,095 all-unigenes from both samples were assembled and annotated, and based on sequence similarity search with known proteins, a total of 56,668 unigenes was obtained. Out of these annotated unigenes, 54,920 were assigned to the NCBI non-redundant protein (Nr database, 35,448 to the Swiss-prot database, 43,051 to gene ontology (GO, and 19,986 to clusters of orthologous groups (COG. Searching in the Kyoto encyclopedia of genes and genomes (KEGG pathway database indicated that 32,200 unigenes were mapped to 128 KEGG pathways. Moreover, we obtained several genes showing a wide range of expression levels. We also identified a total of 749 ginsenoside biosynthetic enzyme genes and 12 promising pleiotropic drug resistance (PDR genes related to ginsenoside transport.

  18. Identification of a reproductive-specific, putative lipid transport protein gene in a queenless ponerine ant Diacamma sp.

    Science.gov (United States)

    Okada, Yasukazu; Miyazaki, Satoshi; Koshikawa, Shigeyuki; Cornette, Richard; Maekawa, Kiyoto; Tsuji, Kazuki; Miura, Toru

    2010-11-01

    Of the various characteristics of social insects, communication for reproductive differentiation is one of the most important and basic social interactions among colony members. To elucidate the molecular basis underlying this process, genes responsible for reproductive differentiation in Diacamma were screened using fluorescent differential display. Differential display, together with real-time quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR), revealed that a gene belonging to the family of cellular retinaldehyde-binding proteins was specifically expressed in the epidermis of the head, legs, and thorax in reproductives. The deduced protein sequence in the coding region, obtained by rapid amplification of cDNA ends (RACE)-PCR, was found to include cellular retinaldehyde-binding domain (CRAL-TRIO domain), suggesting that DiaCRALDCP functions in transportation of lipids, such as cuticular hydrocarbons. DiaCRALDCP transcript levels immediately decreased 1 day after the gemma mutilation, suggesting that DiaCRALDCP is involved in the physiological changes provoked by the behavioral regulation. Considering these results, the social functions of DiaCRALDCP in Diacamma are discussed.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  20. Ab initio study of spin-dependent transport in carbon nanotubes with iron and vanadium adatoms

    DEFF Research Database (Denmark)

    Fürst, Joachim Alexander; Brandbyge, Mads; Jauho, Antti-Pekka

    2008-01-01

    We present an ab initio study of spin-dependent transport in armchair carbon nanotubes with transition metal adsorbates: iron or vanadium. The method based on density functional theory and nonequilibrium Green's functions is used to compute the electronic structure and zero-bias conductance...... (majority or minority) being scattered depends on the adsorbate and is explained in terms of d-state filling. We contrast the single-walled carbon nanotube results to the simpler case of the adsorbate on a flat graphene sheet with periodic boundary conditions and corresponding width in the zigzag direction...

  1. Putative silicon transport vesicles in the cytoplasm of the diatom Synedra acus during surge uptake of silicon.

    Science.gov (United States)

    Annenkov, Vadim V; Basharina, Tatjana N; Danilovtseva, Elena N; Grachev, Mikhail A

    2013-10-01

    We studied the growth of the araphid pennate diatom Synedra acus subsp. radians (Kützing) Skabichevskii using a fluorescent dye N(1),N(3)-dimethyl-N(1)-(7-nitro-2,1,3-benzoxadiazol-4-yl)propane-1,3-diamine (NBD-N2), which stains growing siliceous frustules but does not stain other subcellular organelles. We used a clonal culture of S. acus that was synchronized by silicon starvation. Epifluorescence microscopy was performed in two different ways with cells stained by the addition of silicic acid and the dye. Individual cells immobilized on glass were observed during the first 15-20 min following the replenishment of silicic acid after silicon starvation. Alternatively, we examined cells of a batch culture at time intervals during 36 h after the replenishment of silicic acid using fluorescence and confocal microscopy. The addition of silicic acid and NBD-N2 resulted in the rapid (1-2 min) formation of several dozen green fluorescent submicrometer particles (GFSPs) in the cytoplasm, which was accompanied by the accumulation of fluorescent silica inside silica deposition vesicles (SDVs) along their full length. In 5-15 min, GFSPs disappeared from the cytoplasm. Mature siliceous valves were formed within the SDVs during the subsequent 14-16 h. In the next 8-10 h, GFSPs appeared again in the cytoplasm of daughter cells. The data obtained confirm observations about the two-stage mechanism of silicon assimilation, which includes rapid silicon uptake (surge uptake) followed by slow silica deposition. It is likely that the observed GFSPs are silicon transport vesicles, which were first proposed by Schmid and Schulz in (Protoplasma 100:267-288, 1979).

  2. Specific expression of the vacuolar iron transporter, TgVit, causes iron accumulation in blue-colored inner bottom segments of various tulip petals.

    Science.gov (United States)

    Momonoi, Kazumi; Tsuji, Toshiaki; Kazuma, Kohei; Yoshida, Kumi

    2012-01-01

    Several flowers of Tulipa gesneriana exhibit a blue color in the bottom segments of the inner perianth. We have previously reported the inner-bottom tissue-specific iron accumulation and expression of the vacuolar iron transporter, TgVit1, in tulip cv. Murasakizuisho. To clarify whether the TgVit1-dependent iron accumulation and blue-color development in tulip petals are universal, we analyzed anthocyanin, its co-pigment components, iron contents and the expression of TgVit1 mRNA in 13 cultivars which show a blue color in the bottom segments of the inner perianth accompanying yellow- and white-colored inner-bottom petals. All of the blue bottom segments contained the same anthocyanin component, delphinidin 3-rutinoside. The flavonol composition varied with cultivar and tissue part. The major flavonol in the bottom segments of the inner perianth was rutin. The iron content in the upper part was less than that in the bottom segments of the inner perianth. The iron content in the yellow and white petals was higher in the bottom segment of the inner perianth than in the upper tissues. TgVit1 mRNA expression was apparent in all of the bottom tissues of the inner perianth. The result of a reproduction experiment by mixing the constituents suggests that the blue coloration in tulip petals is generally caused by iron complexation to delphinidin 3-rutinoside and that the iron complex is solubilized and stabilized by flavonol glycosides. TgVit1-dependent iron accumulation in the bottom segments of the inner perianth might be controlled by an unknown system that differentiated the upper parts and bottom segments of the inner perianth.

  3. RhBG and RhCG, the putative ammonia transporters, are expressed in the same cells in the distal nephron.

    Science.gov (United States)

    Quentin, Fabienne; Eladari, Dominique; Cheval, Lydie; Lopez, Claude; Goossens, Dominique; Colin, Yves; Cartron, Jean-Pierre; Paillard, Michel; Chambrey, Régine

    2003-03-01

    Two nonerythroid homologs of the blood group Rh proteins, RhCG and RhBG, which share homologies with specific ammonia transporters in primitive organisms and plants, could represent members of a new family of proteins involved in ammonia transport in the mammalian kidney. Consistent with this hypothesis, the expression of RhCG was recently reported at the apical pole of all connecting tubule (CNT) cells as well as in intercalated cells of collecting duct (CD). To assess the localization along the nephron of RhBG, polyclonal antibodies against the Rh type B glycoprotein were generated. In immunoblot experiments, a specific polypeptide of Mr approximately 50 kD was detected in rat kidney cortex and in outer and inner medulla membrane fractions. Immunocytochemical studies revealed RhBG expression in distal nephron segments within the cortical labyrinth, medullary rays, and outer and inner medulla. RhBG expression was restricted to the basolateral membrane of epithelial cells. The same localization was observed in rat and mouse kidney. RT-PCR analysis on microdissected rat nephron segments confirmed that RhBG mRNAs were chiefly expressed in CNT and cortical and outer medullary CD. Double immunostaining with RhCG demonstrated that RhBG and RhCG were coexpressed in the same cells, but with a basolateral and apical localization, respectively. In conclusion, RhBG and RhCG are present in a major site of ammonia secretion in the kidney, i.e., the CNT and CD, in agreement with their putative role in ammonium transport.

  4. Arabidopsis copper transport protein COPT2 participates in the cross talk between iron deficiency responses and low-phosphate signaling.

    Science.gov (United States)

    Perea-García, Ana; Garcia-Molina, Antoni; Andrés-Colás, Nuria; Vera-Sirera, Francisco; Pérez-Amador, Miguel A; Puig, Sergi; Peñarrubia, Lola

    2013-05-01

    Copper and iron are essential micronutrients for most living organisms because they participate as cofactors in biological processes, including respiration, photosynthesis, and oxidative stress protection. In many eukaryotic organisms, including yeast (Saccharomyces cerevisiae) and mammals, copper and iron homeostases are highly interconnected; yet, such interdependence is not well established in higher plants. Here, we propose that COPT2, a high-affinity copper transport protein, functions under copper and iron deficiencies in Arabidopsis (Arabidopsis thaliana). COPT2 is a plasma membrane protein that functions in copper acquisition and distribution. Characterization of the COPT2 expression pattern indicates a synergic response to copper and iron limitation in roots. We characterized a knockout of COPT2, copt2-1, that leads to increased resistance to simultaneous copper and iron deficiencies, measured as reduced leaf chlorosis and improved maintenance of the photosynthetic apparatus. We propose that COPT2 could play a dual role under iron deficiency. First, COPT2 participates in the attenuation of copper deficiency responses driven by iron limitation, possibly to minimize further iron consumption. Second, global expression analyses of copt2-1 versus wild-type Arabidopsis plants indicate that low-phosphate responses increase in the mutant. These results open up new biotechnological approaches to fight iron deficiency in crops.

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

    Science.gov (United States)

    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. Copyright © 2013 Elsevier B.V. All rights reserved.

  6. AmSUT1, a Sucrose Transporter in Collection and Transport Phloem of the Putative Symplastic Phloem Loader Alonsoa meridionalis1

    Science.gov (United States)

    Knop, Christian; Stadler, Ruth; Sauer, Norbert; Lohaus, Gertrud

    2004-01-01

    A sucrose (Suc) transporter cDNA has been cloned from Alonsoa meridionalis, a member of the Scrophulariaceae. This plant species has an open minor vein configuration and translocates mainly raffinose and stachyose in addition to Suc in the phloem (C. Knop, O. Voitsekhovskaja, G. Lohaus [2001] Planta 213: 80–91). These are typical properties of symplastic phloem loaders. For functional characterization, AmSUT1 cDNA was expressed in bakers' yeast (Saccharomyces cerevisiae). Substrate and inhibitor specificities, energy dependence, and Km value of the protein agree well with the properties measured for other Suc transporters of apoplastic phloem loaders. A polyclonal antiserum against the 17 N-terminal amino acids of the A. meridionalis Suc transporter AmSUT1 was used to determine the cellular localization of the AmSUT1 protein. Using fluorescence labeling on sections from A. meridionalis leaves and stems, AmSUT1 was localized exclusively in phloem cells. Further histological characterization identified these cells as companion cells and sieve elements. p-Chloromercuribenzenesulfonic acid affected the sugar exudation of cut leaves in such a way that the exudation rates of Suc and hexoses decreased, whereas those of raffinose and stachyose increased. The data presented indicate that phloem loading of Suc and retrieval of Suc in A. meridionalis are at least partly mediated by the activity of AmSUT1 in addition to symplastic phloem loading. PMID:14730068

  7. Knockdown of copper-transporting ATPase 1 (Atp7a) impairs iron flux in fully-differentiated rat (IEC-6) and human (Caco-2) intestinal epithelial cells.

    Science.gov (United States)

    Ha, Jung-Heun; Doguer, Caglar; Collins, James F

    2016-09-01

    Intestinal iron absorption is highly regulated since no mechanism for iron excretion exists. We previously demonstrated that expression of an intestinal copper transporter (Atp7a) increases in parallel with genes encoding iron transporters in the rat duodenal epithelium during iron deprivation (Am. J. Physiol.: Gastrointest. Liver Physiol., 2005, 288, G964-G971). This led us to postulate that Atp7a may influence intestinal iron flux. Therefore, to test the hypothesis that Atp7a is required for optimal iron transport, we silenced Atp7a in rat IEC-6 and human Caco-2 cells. Iron transport was subsequently quantified in fully-differentiated cells plated on collagen-coated, transwell inserts. Interestingly, (59)Fe uptake and efflux were impaired in both cell lines by Atp7a silencing. Concurrent changes in the expression of key iron transport-related genes were also noted in IEC-6 cells. Expression of Dmt1 (the iron importer), Dcytb (an apical membrane ferrireductase) and Fpn1 (the iron exporter) was decreased in Atp7a knockdown (KD) cells. Paradoxically, cell-surface ferrireductase activity increased (>5-fold) in Atp7a KD cells despite decreased Dcytb mRNA expression. Moreover, increased expression (>10-fold) of hephaestin (an iron oxidase involved in iron efflux) was associated with increased ferroxidase activity in KD cells. Increases in ferrireductase and ferroxidase activity may be compensatory responses to increase iron flux. In summary, in these reductionist models of the mammalian intestinal epithelium, Atp7a KD altered expression of iron transporters and impaired iron flux. Since Atp7a is a copper transporter, it is a logical supposition that perturbations in intracellular copper homeostasis underlie the noted biologic changes in these cell lines.

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

    DEFF Research Database (Denmark)

    Hansen, Jakob Bondo; Tonnesen, Morten Fog; Madsen, Andreas Nygaard

    2012-01-01

    divalent metal transporter 1 (DMT1) expression correlating with increased ß 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, ß cells...

  9. The putative Na⁺/Cl⁻-dependent neurotransmitter/osmolyte transporter inebriated in the Drosophila hindgut is essential for the maintenance of systemic water homeostasis.

    Science.gov (United States)

    Luan, Zhuo; Quigley, Caitlin; Li, Hong-Sheng

    2015-01-23

    Most organisms are able to maintain systemic water homeostasis over a wide range of external or dietary osmolarities. The excretory system, composed of the kidneys in mammals and the Malpighian tubules and hindgut in insects, can increase water conservation and absorption to maintain systemic water homeostasis, which enables organisms to tolerate external hypertonicity or desiccation. However, the mechanisms underlying the maintenance of systemic water homeostasis by the excretory system have not been fully characterized. In the present study, we found that the putative Na(+)/Cl(-)-dependent neurotransmitter/osmolyte transporter inebriated (ine) is expressed in the basolateral membrane of anterior hindgut epithelial cells. This was confirmed by comparison with a known basolateral localized protein, the α subunit of Na(+)-K(+) ATPase (ATPα). Under external hypertonicity, loss of ine in the hindgut epithelium results in severe dehydration without damage to the hindgut epithelial cells, implicating a physiological failure of water conservation/absorption. We also found that hindgut expression of ine is required for water conservation under desiccating conditions. Importantly, specific expression of ine in the hindgut epithelium can completely restore disrupted systemic water homeostasis in ine mutants under both conditions. Therefore, ine in the Drosophila hindgut is essential for the maintenance of systemic water homeostasis.

  10. Enhanced Grain Iron Levels in Rice Expressing an IRON-REGULATED METAL TRANSPORTER, NICOTIANAMINE SYNTHASE, and FERRITIN Gene Cassette

    Science.gov (United States)

    Boonyaves, Kulaporn; Wu, Ting-Ying; Gruissem, Wilhelm; Bhullar, Navreet K.

    2017-01-01

    Micronutrient malnutrition is widespread, especially in poor populations across the globe, and iron deficiency anemia is one of the most prevalent forms of micronutrient deficiencies. Iron deficiency anemia has severe consequences for human health, working ability, and quality of life. Several interventions including iron supplementation and food fortification have been attempted and met with varied degrees of success. Rice, which is a staple food for over half of the world’s population, is an important target crop for iron biofortification. The genetic variability of iron content in the rice germplasm is very narrow, and thus, conventional breeding has not been successful in developing high iron rice varieties. Therefore, genetic engineering approaches have targeted at increasing iron uptake, translocation, and storage in the rice endosperm. We previously reported that AtIRT1, when expressed together with AtNAS1 and PvFERRITIN (PvFER) in high-iron (NFP) rice, has a synergistic effect of further increasing the iron concentration of polished rice grains. We have now engineered rice expressing AtIRT1, AtNAS1, and PvFER as a single locus gene cassette and compared the resulting lines with transgenic lines expressing AtIRT1 and PvFER gene cassettes. We also evaluated the efficacies of the MsENOD12B and native AtIRT1 promoters for the expression of AtIRT1 in rice in both types of gene cassettes, and found the native AtIRT1 promoter to be a better choice for driving the AtIRT1 expression in our biofortification strategy. All the single insertion transgenic lines have significant increases of iron concentration, both in polished and unpolished grains, but the concerted expression of AtIRT1, AtNAS1, and PvFER resulted to be a more effective strategy in achieving the highest iron increases of up to 10.46 μg/g dry weight. Furthermore, the transformed high iron lines grew better under iron deficiency growth conditions and also have significantly increased grain zinc

  11. Transport of zero-valent iron nanoparticles in carbonate-rich porous aquifers

    Science.gov (United States)

    Laumann, S.; Micic, V.; Hofmann, T.

    2012-04-01

    Use of nanoscale zero-valent iron (nZVI) for in situ dechlorination of chlorinated solvents in groundwater is a promising remediation technology, due to a high dechlorination efficiency of nZVI and possible applications in e.g., great depth or under above-ground infrastructure. The success of the in situ nZVI dechlorination strongly depends on the particle delivery to the contaminants. Previous studies reported a limited transport of nZVI through porous media (cm- to dm-range) and this has been recognized as one of the major obstacles in a widespread utilization of this technology (TRATNYEK & JOHNSON, 2006). Factors that limit the transport are particle aggregation and deposition onto the aquifer solids. Both depend on particle properties (e.g., size, shape, iron content, surface coating, surface charge), on concentrations of suspensions, and on site-specific parameters, such as the groundwater chemistry and the properties and inhomogeneity of the aquifer material. Adsorbed anionic polyelectrolyte coatings provide electrostatic double layer repulsions between negatively charged nZVI particles (SALEH ET AL., 2007), hindering their aggregation and also deposition on the negatively charged quartz surfaces (usually prevailing in aquifers). However, it is shown that the presence of surface charge heterogeneities in the aquifer effects the particle transport (JOHNSON ET AL., 1996). Carbonates, iron oxides, and the edges of clay minerals, for instance, carry a positive surface charge at neutral pH (often encountered in groundwater). This leads to a favorable deposition of negatively charged nZVI particles onto carbonates, metal oxide impurities or clay edges, and finally to a decreased particle transport. Considering the high proportion of carbonates commonly encountered in Alpine porous aquifers, in this study we aimed to evaluate the transport of commercially available polyelectrolyte coated nZVI (polyacrylic acid coated-nZVI, NANOIRON s.r.o., CZ) in both quartz and

  12. Modelling of neutron and photon transport in iron and concrete radiation shieldings by the Monte Carlo method - Version 2

    CERN Document Server

    Žukauskaite, A; Plukiene, R; Plukis, A

    2007-01-01

    Particle accelerators and other high energy facilities produce penetrating ionizing radiation (neutrons and γ-rays) that must be shielded. The objective of this work was to model photon and neutron transport in various materials, usually used as shielding, such as concrete, iron or graphite. Monte Carlo method allows obtaining answers by simulating individual particles and recording some aspects of their average behavior. In this work several nuclear experiments were modeled: AVF 65 – γ-ray beams (1-10 MeV), HIMAC and ISIS-800 – high energy neutrons (20-800 MeV) transport in iron and concrete. The results were then compared with experimental data.

  13. Characterization of Three New Glutaredoxin Genes in the Arbuscular Mycorrhizal Fungus Rhizophagus irregularis: Putative Role of RiGRX4 and RiGRX5 in Iron Homeostasis

    Science.gov (United States)

    Tamayo, Elisabeth; Benabdellah, Karim; Ferrol, Nuria

    2016-01-01

    Glutaredoxins (GRXs) are small ubiquitous oxidoreductases involved in the regulation of the redox state in living cells. In an attempt to identify the full complement of GRXs in the arbuscular mycorrhizal (AM) fungus Rhizophagus irregularis, three additional GRX homologs, besides the formerly characterized GintGRX1 (renamed here as RiGRX1), were identified. The three new GRXs (RiGRX4, RiGRX5 and RiGRX6) contain the CXXS domain of monothiol GRXs, but whereas RiGRX4 and RiGRX5 belong to class II GRXs, RiGRX6 belongs to class I together with RiGRX1. By using a yeast expression system, we observed that the newly identified homologs partially reverted sensitivity of the GRX deletion yeast strains to external oxidants. Furthermore, our results indicated that RiGRX4 and RiGRX5 play a role in iron homeostasis in yeast. Gene expression analyses revealed that RiGRX1 and RiGRX6 were more highly expressed in the intraradical (IRM) than in the extraradical mycelium (ERM). Exposure of the ERM to hydrogen peroxide induced up-regulation of RiGRX1, RiGRX4 and RiGRX5 gene expression. RiGRX4 expression was also up-regulated in the ERM when the fungus was grown in media supplemented with a high iron concentration. These data indicate the two monothiol class II GRXs, RiGRX4 and RiGRX5, might be involved in oxidative stress protection and in the regulation of fungal iron homeostasis. Increased expression of RiGRX1 and RiGRX6 in the IRM suggests that these GRXs should play a key role in oxidative stress protection of R. irregularis during its in planta phase. PMID:26900849

  14. Characterization of Three New Glutaredoxin Genes in the Arbuscular Mycorrhizal Fungus Rhizophagus irregularis: Putative Role of RiGRX4 and RiGRX5 in Iron Homeostasis.

    Directory of Open Access Journals (Sweden)

    Elisabeth Tamayo

    Full Text Available Glutaredoxins (GRXs are small ubiquitous oxidoreductases involved in the regulation of the redox state in living cells. In an attempt to identify the full complement of GRXs in the arbuscular mycorrhizal (AM fungus Rhizophagus irregularis, three additional GRX homologs, besides the formerly characterized GintGRX1 (renamed here as RiGRX1, were identified. The three new GRXs (RiGRX4, RiGRX5 and RiGRX6 contain the CXXS domain of monothiol GRXs, but whereas RiGRX4 and RiGRX5 belong to class II GRXs, RiGRX6 belongs to class I together with RiGRX1. By using a yeast expression system, we observed that the newly identified homologs partially reverted sensitivity of the GRX deletion yeast strains to external oxidants. Furthermore, our results indicated that RiGRX4 and RiGRX5 play a role in iron homeostasis in yeast. Gene expression analyses revealed that RiGRX1 and RiGRX6 were more highly expressed in the intraradical (IRM than in the extraradical mycelium (ERM. Exposure of the ERM to hydrogen peroxide induced up-regulation of RiGRX1, RiGRX4 and RiGRX5 gene expression. RiGRX4 expression was also up-regulated in the ERM when the fungus was grown in media supplemented with a high iron concentration. These data indicate the two monothiol class II GRXs, RiGRX4 and RiGRX5, might be involved in oxidative stress protection and in the regulation of fungal iron homeostasis. Increased expression of RiGRX1 and RiGRX6 in the IRM suggests that these GRXs should play a key role in oxidative stress protection of R. irregularis during its in planta phase.

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

    Science.gov (United States)

    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.

  16. Impact of Subsurface Heterogeneities on nano-Scale Zero Valent Iron Transport

    Science.gov (United States)

    Krol, M. M.; Sleep, B. E.; O'Carroll, D. M.

    2011-12-01

    Nano-scale zero valent iron (nZVI) has been applied as a remediation technology at sites contaminated with chlorinated compounds and heavy metals. Although laboratory studies have demonstrated high reactivity for the degradation of target contaminants, the success of nZVI in the field has been limited due to poor subsurface mobility. When injected into the subsurface, nZVI tends to aggregate and be retained by subsurface soils. As such nZVI suspensions need to be stabilized for increased mobility. However, even with stabilization, soil heterogeneities can still lead to non-uniform nZVI transport, resulting in poor distribution and consequently decreased degradation of target compounds. Understanding how nZVI transport can be affected by subsurface heterogeneities can aid in improving the technology. This can be done with the use of a numerical model which can simulate nZVI transport. In this study CompSim, a finite difference groundwater model, is used to simulate the movement of nZVI in a two-dimensional domain. CompSim has been shown in previous studies to accurately predict nZVI movement in the subsurface, and is used in this study to examine the impact of soil heterogeneity on nZVI transport. This work also explores the impact of different viscosities of the injected nZVI suspensions (corresponding to different stabilizing polymers) and injection rates on nZVI mobility. Analysis metrics include travel time, travel distance, and average nZVI concentrations. Improving our understanding of the influence of soil heterogeneity on nZVI transport will lead to improved field scale implementation and, potentially, to more effective remediation of contaminated sites.

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

    Science.gov (United States)

    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

    2012-10-03

    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. Copyright © 2012 Elsevier Inc. All rights reserved.

  18. Characterization of fluorescent iron nanoparticles—candidates for multimodal tracking of neuronal transport

    Directory of Open Access Journals (Sweden)

    Christina R. Kyrtsos

    2016-08-01

    Full Text Available Magnetic nanoparticles were coated with either dextran or polyacrylic acid (PAA, and compared as potential traceable carriers for targeted intraneuronal therapeutics. Nanoparticles were fabricated using a chemical reduction method and their number mean diameter, aggregation, surface chemistry, crystal structure and magnetic properties were characterized. The crystalline core of the dextran-coated nanoparticles was Fe3O4, while the PAA-coated sample had an iron core. The dextran-coated iron oxide nanoparticles (DIONs and PAA-coated iron nanoparticles (PAINs were both stable and had a similar mean diameter of less than 10 nm. However, morphologically, the PAINs were well dispersed, while the DIONs aggregated. DIONs exhibited the presence of hysteresis and ferromagnetic properties due to aggregation, while PAINs displayed superparamagnetic behavior. Surface chemistry analysis after 2 weeks of being exposed to air indicated that DIONs oxidized to Fe2O3, while PAINs were composed of a metallic Fe core and a mixed oxidation state shell. Based on these analyses, we concluded that PAINs are stronger candidates for examining axonal transport, since they were less prone to aggregation, offered a stronger magnetic signal, and were less oxidized. Neurotoxicity analysis of PAINs revealed that no significant toxicity was observed compared to negative controls for concentrations up to 1 mg/ml, thus further indicating their potential utility for biological applications. Finally, we successfully conjugated PAINs to a fluorophore, rhodamine 110 chloride, through a simple two-step reaction, demonstrating the feasibility of functionalizing PAINs. This study suggests that PAINs should be further evaluated as a candidate technology for intraneuronal diagnostics and therapy.

  19. Induction of nitrate uptake in maize roots: expression of a putative high-affinity nitrate transporter and plasma membrane H+-ATPase isoforms.

    Science.gov (United States)

    Santi, Simonetta; Locci, Geraldine; Monte, Rossella; Pinton, Roberto; Varanini, Zeno

    2003-08-01

    An investigation was carried out to assess the effect of nitrate supply on the root plasma membrane (PM) H+-ATPase of etiolated maize (Zea mays L.) seedlings grown in hydroponics. The treatment induced higher uptake rates of the anion and the expression of a putative high-affinity nitrate transporter gene (ZmNRT2.1), the first to be identified in maize. Root PM H+-ATPase activity displayed a similar time-course pattern as that of net nitrate uptake and investigations were carried out to determine which of the two isoforms reported to date in maize, MHA1 and 2, responded to the treatment. MHA1 was not expressed under the conditions analysed. Genome analysis revealed that MHA2, described as the most abundant form in all maize tissues, was not present in the maize hybrid investigated, but a similar form was found instead and named MHA3. A second gene (named MHA4) was also identified and partially sequenced. Both genes, classified as members of the PM H+-ATPase subfamily II, responded to nitrate supply, although to different degrees: MHA4, in particular, proved more sensitive than MHA3, with a greater up- and down-regulation in response to the treatment. Increased expression of subfamily II genes resulted in higher steady-state levels of the enzyme in the root tissues and enhanced ATP-hydrolysing activity. The results support the idea that greater proton-pumping activity is required when nitrate inflow increases and suggest that nitrate may be the signal triggering the expression of the two members of PM H+-ATPase subfamily II.

  20. A putative amino acid ABC transporter substrate-binding protein, NMB1612, from Neisseria meningitidis, induces murine bactericidal antibodies against meningococci expressing heterologous NMB1612 proteins.

    Science.gov (United States)

    Hung, Miao-Chiu; Humbert, María Victoria; Laver, Jay R; Phillips, Renee; Heckels, John E; Christodoulides, Myron

    2015-08-26

    The nmb1612 (NEIS1533) gene encoding the ~27-kDa putative amino acid ATP-binding cassette (ABC) transporter, periplasmic substrate-binding protein from Neisseria meningitidis serogroup B (MenB) strain MC58 was cloned and expressed in Escherichia coli, and the purified recombinant (r)NMB1612 was used for animal immunization studies. Immunization of mice with rNMB1612 adsorbed to Al(OH)3 and in liposomes with and without MPLA, induced antiserum with bactericidal activity in an assay using baby rabbit complement, against the homologous strain MC58 (encoding protein representative of Allele 62) and killed heterologous strains encoding proteins of three other alleles (representative of Alleles 1, 64 and 68), with similar SBA titres. However, strain MC58 was not killed (titre protein was killed (median titres of 16-64 in the hSBA). Analysis of the NMB1612 amino acid sequences from 4351 meningococcal strains in the pubmlst.org/Neisseria database and a collection of 13 isolates from colonized individuals and from patients, showed that antibodies raised against rNMB1612 could potentially kill at least 72% of the MenB strains in the complete sequence database. For MenB disease occurring specifically in the UK from 2013 to 2015, >91% of the isolates causing disease in this recent period expressed NMB1612 protein encoded by Allele 1 and could be potentially killed by sera raised to the recombinant antigen in the current study. The NMB1612 protein was surface-accessible and expressed by different meningococcal strains. In summary, the properties of (i) NMB1612 protein conservation and expression, (ii) limited amino acid sequence variation between proteins encoded by different alleles, and (iii) the ability of a recombinant protein to induce cross-strain bactericidal antibodies, would all suggest a promising antigen for consideration for inclusion in new meningococcal vaccines.

  1. Influence of yttrium iron garnet thickness and heater opacity on the nonlocal transport of electrically and thermally excited magnons

    NARCIS (Netherlands)

    Shan, Juan; Cornelissen, Ludo J.; Vlietstra, Nynke; Ben Youssef, Jamal; Kuschel, Timo; Duine, Rembert; Van Wees, Bart J.

    2016-01-01

    We studied the nonlocal transport behavior of both electrically and thermally excited magnons in yttrium iron garnet (YIG) as a function of its thickness. For electrically injected magnons, the nonlocal signals decrease monotonically as the YIG thickness increases. For the nonlocal behavior of the t

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

    Energy Technology Data Exchange (ETDEWEB)

    Kayaaltı, Zeliha, E-mail: kayaalti@ankara.edu.tr; 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.

  3. Influence of silicate on the transport of bacteria in quartz sand and iron mineral-coated sand.

    Science.gov (United States)

    Dong, Zhe; Yang, Haiyan; Wu, Dan; Ni, Jinren; Kim, Hyunjung; Tong, Meiping

    2014-11-01

    The influence of silicate on the transport and deposition of bacteria (Escherichia coli) in packed porous media were examined at a constant 20 mM ionic strength with different silicate concentrations (from 0 to 1 mM) at pH 7. Transport experiments were performed in two types of representative porous media, both bare quartz sand and iron mineral-coated quartz sand. In bare quartz sand, the breakthrough plateaus in the presence of silicate in suspensions were lower and the corresponding retained profiles were higher than those without silicate ions, indicating that the presence of silicate in suspensions decreased cell transport in bare quartz sand. Moreover, the decrease of bacteria transport in quartz sand induced by silicate was more pronounced with increasing silicate concentrations from 0 to 1 mM. However, when EPS was removed from cell surfaces, the presence of silicate in cell suspensions (with different concentrations) did not affect the transport behavior of bacteria in quartz sand. The interaction of silicate with EPS on cell surfaces negatively decreased the zeta potentials of bacteria, resulting in the decreased cell transport in bare quartz sand when silicate was copresent in bacteria suspensions. In contrast, the presence of silicate in suspensions increased cell transport in iron mineral-coated sand. Silicate ions competed with bacteria for the adsorption sites on mineral-coated sand, contributing to the increased cell transport in mineral-coated sand with silicate present in cell suspensions.

  4. Iron and pH-responsive FtrABCD ferrous iron utilization system of Bordetella species

    Science.gov (United States)

    Brickman, Timothy J.; Armstrong, Sandra K.

    2012-01-01

    Summary A putative operon encoding an uncharacterized ferrous iron transport (FtrABCD) system was previously identified in cDNA microarray studies. In growth studies using buffered medium at pH values ranging from pH 6.0 to 7.6, Bordetella pertussis and Bordetella bronchiseptica FtrABCD system mutants showed dramatic reductions in growth yields under iron-restricted conditions at pH 6.0, but had no growth defects at pH 7.6. Supplementation of culture medium with 2 mM ascorbate reductant was inhibitory to alcaligin siderophore-dependent growth at pH 7.6, but had a neglible effect on FtrABCD system-dependent iron assimilation at pH 6.0 consistent with its predicted specificity for ferrous iron. Unlike Bordetella siderophore-dependent and haem iron transport systems, and in agreement with its hypothesized role in transport of inorganic iron from periplasm to cytoplasm, FtrABCD system function did not require the TonB energy transduction complex. Gene fusion analysis revealed that ftrABCD promoter activity was maximal under iron-restricted growth conditions at acidic pH. The pH of human airway surface fluids ranges from pH 5.5 to 7.9, and the FtrABCD system may supply ferrous iron necessary for Bordetella growth in acidic host microenvironments in which siderophores are ineffective for iron retrieval. PMID:22924881

  5. Transport measurements on superconducting iron pnictides and Heusler compounds; Transportmessungen an Supraleitenden Eisenpniktiden und Heusler-Verbindungen

    Energy Technology Data Exchange (ETDEWEB)

    Bombor, Dirk

    2014-09-05

    In this work, results of electronic transport measurements are discussed for superconducting iron pnictides as well as for ferromagnetic Heusler compounds. The iron pnictides are a recently discovered class of high temperature superconductors where magnetism might play a crucial role. While the 122-pnictides show antiferromagnetism and migrate to the superconducting state upon doping, ferromagnetism has been observed in doped LiFeAs. On the other hand, in the undoped state this material shows interesting superconducting properties. Among other properties, Heusler compounds are well known due to their ferromagnetism. Co{sub 2}FeSi, which was investigated in this work, is one of the strongest ferromagnets. Beside this, one predicts this compound to be a half-metallic ferromagnet with completely spin polarized electronic transport where all conducting electrons have the same spin. The here addressed properties can well be investigated with the method of electronic transport measurements, whose results on single crystals are discussed in this work.

  6. Cytotoxicity, Intestinal Transport, and Bioavailability of Dispersible Iron and Zinc Supplements

    Directory of Open Access Journals (Sweden)

    Jae-Min Oh

    2017-04-01

    Full Text Available Iron or zinc deficiency is one of the most important nutritional disorders which causes health problem. However, food fortification with minerals often induces unacceptable organoleptic changes during preparation process and storage, has low bioavailability and solubility, and is expensive. Nanotechnology surface modification to obtain novel characteristics can be a useful tool to overcome these problems. In this study, the efficacy and potential toxicity of dispersible Fe or Zn supplement coated in dextrin and glycerides (SunActive FeTM and SunActive ZnTM were evaluated in terms of cytotoxicity, intestinal transport, and bioavailability, as compared with each counterpart without coating, ferric pyrophosphate (FePP and zinc oxide (ZnO nanoparticles (NPs, respectively. The results demonstrate that the cytotoxicity of FePP was not significantly affected by surface modification (SunActive FeTM, while SunActive ZnTM was more cytotoxic than ZnO-NPs. Cellular uptake and intestinal transport efficiency of SunActive FeTM were significantly higher than those of its counterpart material, which was in good agreement with enhanced oral absorption efficacy after a single-dose oral administration to rats. These results seem to be related to dissolution, particle dispersibility, and coating stability of materials depending on suspending media. Both SunActiveTM products and their counterpart materials were determined to be primarily transported by microfold (M cells through the intestinal epithelium. It was, therefore, concluded that surface modification of food fortification will be a useful strategy to enhance oral absorption efficiency at safe levels.

  7. Performance evaluation of cast iron pipe for crude oil and salt water transportation; Avaliacao e desempenho de duto de aco fundido no transporte de petroleo com aguas salgadas

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Carlos Alexandre Martins da [PETROBRAS Transporte S.A. (TRANSPETRO), Rio de Janeiro, RJ (Brazil); Mainier, Fernando B. [Universidade Federal Fluminense, Niteroi, RJ (Brazil)

    2005-07-01

    The present paper aims to study and to evaluate the performance of casting iron pipe for transportation of salty and produced waters, presented in the oil industry, where salt contents ranging on very large values. The cast iron above mentioned has an yield strength of 23 kg/mm{sup 2}, tensile strength of de 46 kg/mm{sup 2} (minimum) and an elongation of 15%, and contents of some chemical alloys, such as Cr (0,8 -1,3 %), Mn (1,5 % max) and Si (1,%). Nevertheless it is an exploratory study, the dynamic tests of weight loss carried out in laboratory, with specimens machined from a used pipe piece, with salty solution (3,5 % NaCl) aerated media, has shown very promising results, enabling to qualify, satisfactorily, such material for using in transportation and transferring operations of fluids with a high salty contents, such as crude oil. (author)

  8. Performance evaluation of cast iron pipe for crude oil and salt water transportation; Avaliacao e desempenho de duto de aco fundido no transporte de petroleo com aguas salgadas

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Carlos Alexandre Martins da [PETROBRAS Transporte S.A. (TRANSPETRO), Rio de Janeiro, RJ (Brazil); Mainier, Fernando B. [Universidade Federal Fluminense, Niteroi, RJ (Brazil)

    2005-07-01

    The present paper aims to study and to evaluate the performance of casting iron pipe for transportation of salty and produced waters, presented in the oil industry, where salt contents ranging on very large values. The cast iron above mentioned has an yield strength of 23 kg/mm{sup 2}, tensile strength of de 46 kg/mm{sup 2} (minimum) and an elongation of 15%, and contents of some chemical alloys, such as Cr (0,8 -1,3 %), Mn (1,5 % max) and Si (1,%). Nevertheless it is an exploratory study, the dynamic tests of weight loss carried out in laboratory, with specimens machined from a used pipe piece, with salty solution (3,5 % NaCl) aerated media, has shown very promising results, enabling to qualify, satisfactorily, such material for using in transportation and transferring operations of fluids with a high salty contents, such as crude oil. (author)

  9. Column studies on transport of deicing additive benzotriazole in a sandy aquifer and a zerovalent iron barrier.

    Science.gov (United States)

    Jia, Yu; Breedveld, Gijs D; Aagaard, Per

    2007-11-01

    Benzotriazole (BTA), a chemical with wide industrial applications, is a typical additive in deicer/anti-icer used at airport. To achieve a better understanding of the transport behaviour and environmental fate of BTA, laboratory column studies have been performed on subsoil samples from Oslo Airport, Gardermoen. To explore possibilities for aquifer remediation, BTA behaviour was also studied in a column of granular zerovalent iron (Fe(0)). The subsoil column study demonstrates a very limited retardation of BTA. Consecutive loadings of BTA of the subsoil column showed no change of the break-through curve (BTC) and complete desorption was observed. The sorption behaviour of BTA to metallic iron (Fe(0)) was rather complex. Considerable retardation was observed in the Fe(0) column and repeated BTA loading resulted in an earlier break-through. Between 20% and 50% of the input concentration was retained permanently in the iron (Fe(0)) column. The BTA sorption to metallic iron was found to be enhanced by chloride which lowered the break-through concentration (i.e the C/C(0) plateau). The fraction of BTA remaining in the iron column was found to vary with the flow rate, indicating a time dependant multilayer sorption mechanism. The steady increase in the amount of adsorbed BTA to the iron column during loading corresponds to a rather strong bonding of 4-15 BTA layers to the iron surface. A very slow desorption of BTA was observed; even after flushing with 753 pore volumes of BTA free water, 7.5% of the BTA remained in the column. A geochemical model was developed based on PHREEQC-2 to simulate the sorption and transport of BTA in the tested materials. The BTA sorption was modelled with Freundlich sorption isotherms, as earlier determined in batch experiments. A slight adjustment of the Freundlich parameters was required to fit the observed column break-through. However, our model was not able to simulate the long-term retainment of BTA in the granular iron columns. The

  10. Effects of Aging and Colloids on Iron Nanoparticle Transport in Groundwater

    Science.gov (United States)

    Johnson, R. L.; Tratnyek, P. G.; Nurmi, J. T.

    2007-12-01

    Most studies of manufactured nanoparticle transport in aquifer materials have used "fresh" particles in homogenous solutions. However, the role of particle aging and the presence of other colloidal materials may have a significant impact on mobility. We have examined both of these processes using reactive nano-iron particles (RNIP), dynamic light scattering, column studies, and deep-bed filtration theory. In the absence of colloidal materials, RNIP are rapidly removed from porous media by coagulation and attachment to aquifer materials (due in part to their magnetic properties). However, upon aging (in the presence of oxidants ranging in strength from water to carbon tetrachloride), the outer shell of the RNIP will be converted to oxides that are less magnetic and have very different surface charges that result in different sticking coefficients. The presence of colloids (both organic and inorganic) may modify the surfaces of aquifer materials and/or bind with the nanoparticles, and as a consequence, aggregation and sticking coefficients of the nanoparticles can also be significantly altered.

  11. The stabilisation and transportation of dissolved iron from high temperature hydrothermal vent systems

    Science.gov (United States)

    Hawkes, J. A.; Connelly, D. P.; Gledhill, M.; Achterberg, E. P.

    2013-08-01

    Iron (Fe) binding phases in two hydrothermal plumes in the Southern Ocean were studied using a novel voltammetric technique. This approach, reverse titration-competitive ligand exchange-adsorptive cathodic stripping voltammetry, showed that on average 30±21% of dissolved Fe in the hydrothermal plumes was stabilised by chemically labile binding to ligands. The conditional stability constant (log K‧FeL) of the observed complexes was 20.61±0.54 (mean±1 SD) for the two vent sites, intermediate between previous measurements of deep ocean ligands (21.4-23; Kondo et al., 2012) and dissolved weak estuarine ligands (<20; Gerringa et al., 2007). Our results indicate that approximately 7.5% of all hydrothermal Fe was stabilised by complexation with ligands. Furthermore, 47±26% of the dissolved Fe in the plume existed in the colloidal size range (0.02-0.2 μm). Our data suggests that a portion (∼7.5%) of hydrothermal Fe is sufficiently stabilised in the dissolved size fraction (<0.2 μm) to make an important impact on deep ocean Fe distributions. Lateral deep ocean currents transport this hydrothermal Fe as lenses of enhanced Fe concentrations away from mid ocean ridge spreading centres and back arc basins.

  12. Modeling of neutron and photon transport in iron and concrete radiation shields by using Monte Carlo method

    CERN Document Server

    Žukauskaitėa, A; Plukienė, R; Ridikas, D

    2007-01-01

    Particle accelerators and other high energy facilities produce penetrating ionizing radiation (neutrons and γ-rays) that must be shielded. The objective of this work was to model photon and neutron transport in various materials, usually used as shielding, such as concrete, iron or graphite. Monte Carlo method allows obtaining answers by simulating individual particles and recording some aspects of their average behavior. In this work several nuclear experiments were modeled: AVF 65 (AVF cyclotron of Research Center of Nuclear Physics, Osaka University, Japan) – γ-ray beams (1-10 MeV), HIMAC (heavy-ion synchrotron of the National Institute of Radiological Sciences in Chiba, Japan) and ISIS-800 (ISIS intensive spallation neutron source facility of the Rutherford Appleton laboratory, UK) – high energy neutron (20-800 MeV) transport in iron and concrete. The calculation results were then compared with experimental data.compared with experimental data.

  13. Constitutive expression of a barley Fe phytosiderophore transporter increases alkaline soil tolerance and results in iron partitioning between vegetative and storage tissues under stress.

    Science.gov (United States)

    Gómez-Galera, Sonia; Sudhakar, Duraialagaraja; Pelacho, Ana M; Capell, Teresa; Christou, Paul

    2012-04-01

    Cereals have evolved chelation systems to mobilize insoluble iron in the soil, but in rice this process is rather inefficient, making the crop highly susceptible to alkaline soils. We therefore engineered rice to express the barley iron-phytosiderophore transporter (HvYS1), which enables barley plants to take up iron from alkaline soils. A representative transgenic rice line was grown in standard (pH 5.5) or alkaline soil (pH 8.5) to evaluate alkaline tolerance and iron mobilization. Transgenic plants developed secondary tillers and set seeds when grown in standard soil although iron concentration remained similar in leaves and seeds compared to wild type. However, when grown in alkaline soil transgenic plants exhibited enhanced growth, yield and iron concentration in leaves compared to the wild type plants which were severely stunted. Transgenic plants took up iron more efficiently from alkaline soil compared to wild type, indicating an enhanced capacity to increase iron mobility ex situ. Interestingly, all the additional iron accumulated in vegetative tissues, i.e. there was no difference in iron concentration in the seeds of wild type and transgenic plants. Our data suggest that iron uptake from the rhizosphere can be enhanced through expression of HvYS1 and confirm the operation of a partitioning mechanism that diverts iron to leaves rather than seeds, under stress.

  14. Humic acid facilitates the transport of ARS-labeled hydroxyapatite nanoparticles in iron oxyhydroxide-coated sand

    Science.gov (United States)

    Wang, Dengjun; Bradford, Scott A.; Harvey, Ronald W.; Gao, Bin; Cang, Long; Zhou, Dongmei

    2012-01-01

    Hydroxyapatite nanoparticles (nHAP) have been widely used to remediate soil and wastewater contaminated with metals and radionuclides. However, our understanding of nHAP transport and fate is limited in natural environments that exhibit significant variability in solid and solution chemistry. The transport and retention kinetics of Alizarin red S (ARS)-labeled nHAP were investigated in water-saturated packed columns that encompassed a range of humic acid concentrations (HA, 0–10 mg L–1), fractional surface coverage of iron oxyhydroxide coatings on sand grains (λ, 0–0.75), and pH (6.0–10.5). HA was found to have a marked effect on the electrokinetic properties of ARS-nHAP, and on the transport and retention of ARS-nHAP in granular media. The transport of ARS-nHAP was found to increase with increasing HA concentration because of enhanced colloidal stability and the reduced aggregate size. When HA = 10 mg L–1, greater ARS-nHAP attachment occurred with increasing λ because of increased electrostatic attraction between negatively charged nanoparticles and positively charged iron oxyhydroxides, although alkaline conditions (pH 8.0 and 10.5) reversed the surface charge of the iron oxyhydroxides and therefore decreased deposition. The retention profiles of ARS-nHAP exhibited a hyperexponential shape for all test conditions, suggesting some unfavorable attachment conditions. Retarded breakthrough curves occurred in sands with iron oxyhydroxide coatings because of time-dependent occupation of favorable deposition sites. Consideration of the above effects is necessary to improve remediation efficiency of nHAP for metals and actinides in soils and subsurface environments.

  15. Recombinant vacuolar iron transporter family homologue PfVIT from human malaria-causing Plasmodium falciparum is a Fe2+/H+exchanger

    Science.gov (United States)

    Labarbuta, Paola; Duckett, Katie; Botting, Catherine H.; Chahrour, Osama; Malone, John; Dalton, John P.; Law, Christopher J.

    2017-01-01

    Vacuolar iron transporters (VITs) are a poorly understood family of integral membrane proteins that can function in iron homeostasis via sequestration of labile Fe2+ into vacuolar compartments. Here we report on the heterologous overexpression and purification of PfVIT, a vacuolar iron transporter homologue from the human malaria-causing parasite Plasmodium falciparum. Use of synthetic, codon-optimised DNA enabled overexpression of functional PfVIT in the inner membrane of Escherichia coli which, in turn, conferred iron tolerance to the bacterial cells. Cells that expressed PfVIT had decreased levels of total cellular iron compared with cells that did not express the protein. Qualitative transport assays performed on inverted vesicles enriched with PfVIT revealed that the transporter catalysed Fe2+/H+ exchange driven by the proton electrochemical gradient. Furthermore, the PfVIT transport function in this system did not require the presence of any Plasmodium-specific factor such as post-translational phosphorylation. PfVIT purified as a monomer and, as measured by intrinsic protein fluorescence quenching, bound Fe2+ in detergent solution with low micromolar affinity. This study of PfVIT provides material for future detailed biochemical, biophysical and structural studies to advance understanding of the vacuolar iron transporter family of membrane proteins from important human pathogens. PMID:28198449

  16. Knocking down mitochondrial iron transporter (MIT) reprograms primary and secondary metabolism in rice plants.

    Science.gov (United States)

    Vigani, Gianpiero; Bashir, Khurram; Ishimaru, Yasuhiro; Lehmann, Martin; Casiraghi, Fabio Marco; Nakanishi, Hiromi; Seki, Motoaki; Geigenberger, Peter; Zocchi, Graziano; Nishizawa, Naoko K

    2016-03-01

    Iron (Fe) is an essential micronutrient for plant growth and development, and its reduced bioavailability strongly impairs mitochondrial functionality. In this work, the metabolic adjustment in the rice (Oryza sativa) mitochondrial Fe transporter knockdown mutant (mit-2) was analysed. Biochemical characterization of purified mitochondria from rice roots showed alteration in the respiratory chain of mit-2 compared with wild-type (WT) plants. In particular, proteins belonging to the type II alternative NAD(P)H dehydrogenases accumulated strongly in mit-2 plants, indicating that alternative pathways were activated to keep the respiratory chain working. Additionally, large-scale changes in the transcriptome and metabolome were observed in mit-2 rice plants. In particular, a strong alteration (up-/down-regulation) in the expression of genes encoding enzymes of both primary and secondary metabolism was found in mutant plants. This was reflected by changes in the metabolic profiles in both roots and shoots of mit-2 plants. Significant alterations in the levels of amino acids belonging to the aspartic acid-related pathways (aspartic acid, lysine, and threonine in roots, and aspartic acid and ornithine in shoots) were found that are strictly connected to the Krebs cycle. Furthermore, some metabolites (e.g. pyruvic acid, fumaric acid, ornithine, and oligosaccharides of the raffinose family) accumulated only in the shoot of mit-2 plants, indicating possible hypoxic responses. These findings suggest that the induction of local Fe deficiency in the mitochondrial compartment of mit-2 plants differentially affects the transcript as well as the metabolic profiles in root and shoot tissues. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  17. Transport and cycling of iron and hydrogen peroxide in a freshwater stream: Influence of organic acids

    Science.gov (United States)

    Scott, D.T.; Runkel, R.L.; McKnight, Diane M.; Voelker, B.M.; Kimball, B.A.; Carraway, E.R.

    2003-01-01

    An in-stream injection of two dissolved organic acids (phthalic and aspartic acids) was performed in an acidic mountain stream to assess the effects of organic acids on Fe photoreduction and H2O2 cycling. Results indicate that the fate of Fe is dependent on a net balance of oxidative and reductive processes, which can vary over a distance of several meters due to changes in incident light and other factors. Solution phase photoreduction rates were high in sunlit reaches and were enhanced by the organic acid addition but were also limited by the amount of ferric iron present in the water column. Fe oxide photoreduction from the streambed and colloids within the water column resulted in an increase in the diurnal load of total filterable Fe within the experimental reach, which also responded to increases in light and organic acids. Our results also suggest that Fe(II) oxidation increased in response to the organic acids, with the result of offsetting the increase in Fe(II) from photoreductive processes. Fe(II) was rapidly oxidized to Fe(III) after sunset and during the day within a well-shaded reach, presumably through microbial oxidation. H2O 2, a product of dissolved organic matter photolysis, increased downstream to maximum concentrations of 0.25 ??M midday. Kinetic calculations show that the buildup of H2O2 is controlled by reaction with Fe(III), but this has only a small effect on Fe(II) because of the small formation rates of H2O2 compared to those of Fe(II). The results demonstrate the importance of incorporating the effects of light and dissolved organic carbon into Fe reactive transport models to further our understanding of the fate of Fe in streams and lakes.

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

    Science.gov (United States)

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

    2016-02-01

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

  19. Constitutive expression of a barley Fe phytosiderophore transporter increases alkaline soil tolerance and results in iron partitioning between vegetative and storage tissues under stress

    OpenAIRE

    Gómez-Galera, Sonia; Sudhakar, Duraialagaraja; Ana M. Pelacho; Capell, Teresa; Christou, Paul

    2012-01-01

    Cereals have evolved chelation systems to mobilize insoluble iron in the soil, but in rice this process is rather inefficient, making the crop highly susceptible to alkaline soils. We therefore engineered rice to express the barley iron-phytosiderophore transporter (HvYS1), which enables barley plants to take up iron from alkaline soils. A representative transgenic rice line was grown in standard (pH 5.5) or alkaline soil (pH 8.5) to evaluate alkaline tolerance and iron mobilizati...

  20. Interacting Effects of Light and Iron Availability on the Coupling of Photosynthetic Electron Transport and CO2-Assimilation in Marine Phytoplankton.

    Directory of Open Access Journals (Sweden)

    Nina Schuback

    Full Text Available Iron availability directly affects photosynthesis and limits phytoplankton growth over vast oceanic regions. For this reason, the availability of iron is a crucial variable to consider in the development of active chlorophyll a fluorescence based estimates of phytoplankton primary productivity. These bio-optical approaches require a conversion factor to derive ecologically-relevant rates of CO2-assimilation from estimates of electron transport in photosystem II. The required conversion factor varies significantly across phytoplankton taxa and environmental conditions, but little information is available on its response to iron limitation. In this study, we examine the role of iron limitation, and the interacting effects of iron and light availability, on the coupling of photosynthetic electron transport and CO2-assimilation in marine phytoplankton. Our results show that excess irradiance causes increased decoupling of carbon fixation and electron transport, particularly under iron limiting conditions. We observed that reaction center II specific rates of electron transport (ETR(RCII, mol e- mol RCII(-1 s(-1 increased under iron limitation, and we propose a simple conceptual model for this observation. We also observed a strong correlation between the derived conversion factor and the expression of non-photochemical quenching. Utilizing a dataset from in situ phytoplankton assemblages across a coastal--oceanic transect in the Northeast subarctic Pacific, this relationship was used to predict ETR(RCII: CO2-assimilation conversion factors and carbon-based primary productivity from FRRF data, without the need for any additional measurements.

  1. Fur and iron transport proteins in the Brazilian purpuric fever clone of Haemophilus influenzae biogroup aegyptius.

    Science.gov (United States)

    Smoot, L M; Bell, E C; Crosa, J H; Actis, L A

    1999-07-01

    The Brazilian purpuric fever (BPF) clone of Haemophilus influenzae biogroup aegyptius causes a fatal septicaemic disease, resembling fulminant meningococcal sepsis, in children. When isolate F3031 was grown under iron-limiting conditions, the presence of several iron-regulated proteins of 38-110 kDa was revealed by electrophoretic analysis and a Fur homologue was shown by immunoblotting. Dot-blot assays and immunoblotting indicated that BPF cells bound human transferrin and contained transferrin-binding proteins in the outer membrane. However, the binding activity and the biosynthesis of these proteins were detected even under iron-rich conditions. Immunoblot analysis demonstrated the presence of a periplasmic protein related to the ferric iron-binding protein A (FbpA), the major iron-binding protein described in Neisseria spp. However, the FbpA homologue in strain F3031 was constitutively expressed and was smaller than the periplasmic protein detected in H. influenzae type b strain Eagan. The periplasm of strain F3031 also contained a protein related to the Streptococcus parasanguis FimA protein which recently has been shown to be involved in iron acquisition in Yersinia pestis. Although the Eagan and F3031 FimA homologues had a similar mol. wt, of 31 kDa, the expression of the BPF fimA-like gene was not regulated by the iron concentration of the culture medium.

  2. Putative sugar transporters of the mustard leaf beetle Phaedon cochleariae: their phylogeny and role for nutrient supply in larval defensive glands.

    Directory of Open Access Journals (Sweden)

    Magdalena Stock

    Full Text Available BACKGROUND: Phytophagous insects have emerged successfully on the planet also because of the development of diverse and often astonishing defensive strategies against their enemies. The larvae of the mustard leaf beetle Phaedon cochleariae, for example, secrete deterrents from specialized defensive glands on their back. The secretion process involves ATP-binding cassette transporters. Therefore, sugar as one of the major energy sources to fuel the ATP synthesis for the cellular metabolism and transport processes, has to be present in the defensive glands. However, the role of sugar transporters for the production of defensive secretions was not addressed until now. RESULTS: To identify sugar transporters in P. cochleariae, a transcript catalogue was created by Illumina sequencing of cDNA libraries. A total of 68,667 transcripts were identified and 68 proteins were annotated as either members of the solute carrier 2 (SLC2 family or trehalose transporters. Phylogenetic analyses revealed an extension of the mammalian GLUT6/8 class in insects as well as one group of transporters exhibiting distinctive conserved motifs only present in the insect order Coleoptera. RNA-seq data of samples derived from the defensive glands revealed six transcripts encoding sugar transporters with more than 3,000 counts. Two of them are exclusively expressed in the glandular tissue. Reduction in secretions production was accomplished by silencing two of four selected transporters. RNA-seq experiments of transporter-silenced larvae showed the down-regulation of the silenced transporter but concurrently the up-regulation of other SLC2 transporters suggesting an adaptive system to maintain sugar homeostasis in the defensive glands. CONCLUSION: We provide the first comprehensive phylogenetic study of the SLC2 family in a phytophagous beetle species. RNAi and RNA-seq experiments underline the importance of SLC2 transporters in defensive glands to achieve a chemical defense

  3. Investigation of iron metabolism in mice expressing a mutant Menke's copper transporting ATPase (Atp7a protein with diminished activity (Brindled; Mo (Br (/y .

    Directory of Open Access Journals (Sweden)

    Sukru Gulec

    Full Text Available During iron deficiency, perturbations in copper homeostasis have frequently been documented. Previous studies in iron-deprived rats demonstrated that enterocyte and hepatic copper levels increase and a copper transporter (the Menkes Copper ATPase; Atp7a is induced in the duodenal epithelium in parallel to iron transport-related genes (e.g. Dmt1, Dcytb, Fpn1. Moreover, two ferroxidase proteins involved in iron homeostasis, hephaestin expressed in enterocytes and ceruloplasmin, produced and secreted into blood by the liver, are copper-dependent enzymes. We thus aimed to test the hypothesis that Atp7a function is important for the copper-related compensatory response of the intestinal epithelium to iron deficiency. Accordingly, iron homeostasis was studied for the first time in mice expressing a mutant Atp7a protein with minimal activity (Brindled [Mo (Br (/y ]. Mutant mice were rescued by perinatal copper injections, and, after a 7-8 week recovery period, were deprived of dietary iron for 3 weeks (along with WT littermates. Adult Mo (Br (/y mice displayed copper-deficiency anemia but had normal iron status; in contrast, iron-deprived Mo (Br (/y mice were iron deficient and more severely anemic with partial amelioration of the copper-deficient phenotype. Intestinal iron absorption in both genotypes (WT and Mo (Br (/y increased ∼3-fold when mice consumed a low-iron diet and ∼6-fold when mice were concurrently bled. WT mice exhibited no alterations in copper homeostasis in response to iron deprivation or phlebotomy. Conversely, upregulation of iron absorption was associated with increased enterocyte and liver copper levels and serum ferroxidase (ceruloplasmin activity in Mo (Br (/y mice, typifying the response to iron deprivation in many mammalian species. We thus speculate that a copper threshold exists that is necessary to allow appropriate regulate of iron absorption. In summary, Mo (Br (/y mice were able to adequately regulate iron absorption

  4. Electro-osmotic transport of nano zero-valent iron in Boom Clay

    NARCIS (Netherlands)

    Rosales, E.; Loch, J.P.G.; Dias-Ferreira, C.

    2014-01-01

    One of the many problems that impede the successful remediation of soil and groundwater contaminated with chlorinated hydrocarbons occurs when pollutants diffuse into low permeability zones, and become difficultly accessible. Remediation by reductive dechlorination using nanoscale zero-valent iron

  5. Combined transport, magnetization and neutron scattering study of correlated iridates and iron pnictide superconductors

    Science.gov (United States)

    Dhital, Chetan

    The work performed within this thesis is divided into two parts, each focusing primarily on the study of magnetic phase behavior using neutron scattering techniques. In first part, I present transport, magnetization, and neutron scattering studies of materials within the iridium oxide-based Ruddelsden-Popper series [Srn+1IrnO3n+1] compounds Sr 3Ir2O7 (n=2) and Sr2IrO4 (n=1). This includes a comprehensive study of the doped bilayer system Sr 3(Ir1-xRux )2O7. In second part, I present my studies of the effect of uniaxial pressure on magnetic and structural phase behavior of the iron-based high temperature superconductor Ba(Fe1-xCox)2As2. Iridium-based 5d transition metal oxides host rather unusual electronic/magnetic ground states due to strong interplay between electronic correlation, lattice structure and spin-orbit effects. Out of the many oxides containing iridium, the Ruddelsden-Popper series [Srn+1IrnO 3n+1] oxides are some of the most interesting systems to study both from the point of view of physics as well as from potential applications. My work is focused on two members of this series Sr3Ir2O 7 (n=2) and Sr2IrO4 (n=1). In particular, our combined transport, magnetization and neutron scattering studies of Sr 3Ir2O7 (n=2) showed that this system exhibits a complex coupling between charge transport and magnetism. The spin magnetic moments form a G-type antiferromagnetic structure with moments oriented along the c-axis, with an ordered moment of 0.35+/-0.06 muB/Ir. I also performed experiments doping holes in this bilayer Sr3(Ir1-xRu x)2O7 system in order to study the role of electronic correlation in these materials. Our results show that the ruthenium-doped holes remain localized within the Jeff=1/2 Mott insulating background of Sr3Ir2O7, suggestive of 'Mott blocking' and the presence of strong electronic correlation in these materials. Antiferromagnetic order however survives deep into the metallic regime with the same ordering q-vector, suggesting an

  6. Anemia of the Belgrade rat: evidence for defective membrane transport of iron

    Energy Technology Data Exchange (ETDEWEB)

    Bowen, B.J.; Morgan, E.H.

    1987-07-01

    The mechanisms underlying the impaired utilization of transferrin-bound iron by erythroid cells in the anemia of the Belgrade laboratory rat were investigated using reticulocytes from homozygous anemic animals and transferrin labeled with /sup 59/Fe and /sup 125/I. The results were compared with those obtained using reticulocytes from phenylhydrazine-treated rats and iron-deficient rats. Each step in the iron uptake mechanism was investigated, ie, transferrin-receptor interaction, transferrin endocytosis, iron release from transferrin, and transferrin exocytosis. Although there were quantitative differences, no fundamental difference was found in any of the abovementioned aspects of cellular function when the reticulocytes from Belgrade rats were compared with those from iron-deficient animals. The basic defect in the Belgrade reticulocytes must therefore reside in subsequent steps in iron uptake, after it is released from transferrin within endocytotic vesicles, ie, in the mechanism by which it is transferred across the lining membrane of the vesicles into the cell cytosol. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of reticulocyte ghosts extracts demonstrated a prominent protein band of mol wt 69,000 that was absent or present only in low concentration extracts from the other two types of reticulocytes. This may be a result of the genetic defect.

  7. Genome-wide identification, cloning and functional analysis of the Zinc/Iron-regulated transporter-like protein (ZIP) gene family in trifoliate orange (poncirus trifoliata L. Raf.)

    NARCIS (Netherlands)

    Fu, Xing Zheng; Zhou, Xue; Xing, Fei; Ling, Li Li; Chun, Chang Pin; Cao, Li; Aarts, Mark G.M.; Peng, Liang Zhi

    2017-01-01

    Zinc (Zn) and iron (Fe) deficiency are widespread among citrus plants, but the molecular mechanisms regarding uptake and transport of these two essential metal ions in citrus are still unclear. In the present study, 12 members of the Zn/Fe-regulated transporter (ZRT/IRT)-related protein (ZIP)

  8. Genome-wide identification, cloning and functional analysis of the Zinc/Iron-regulated transporter-like protein (ZIP) gene family in trifoliate orange (poncirus trifoliata L. Raf.)

    NARCIS (Netherlands)

    Fu, Xing Zheng; Zhou, Xue; Xing, Fei; Ling, Li Li; Chun, Chang Pin; Cao, Li; Aarts, Mark G.M.; Peng, Liang Zhi

    2017-01-01

    Zinc (Zn) and iron (Fe) deficiency are widespread among citrus plants, but the molecular mechanisms regarding uptake and transport of these two essential metal ions in citrus are still unclear. In the present study, 12 members of the Zn/Fe-regulated transporter (ZRT/IRT)-related protein (ZIP) gen

  9. Identification of a new sucrose transporter in rye-grass (LpSUT2): effect of defoliation and putative fructose sensing.

    Science.gov (United States)

    Berthier, Alexandre; Meuriot, Frédéric; Dédaldéchamp, Fabienne; Lemoine, Rémi; Prud'homme, Marie-Pascale; Noiraud-Romy, Nathalie

    2014-11-01

    Rye-grass fast regrowth after defoliation results from an efficient mobilization of C reserves which are transported as sucrose towards regrowing leaves, and which can be supported by one or several sucrose transporters (SUTs) like LpSUT1. Therefore, our objectives were to isolate, identify, characterize and immunolocalize such sucrose transporters. A protein (LpSUT2) showing a twelve spanning trans-membrane domain, extended N terminal and internal cytoplasmic loop, and kinetic properties consistent with well-known sucrose transporters, was isolated and successfully characterized. Along with LpSUT1, it was mainly localized in mesophyll cells of leaf sheaths and elongating leaf bases. These transporters were also found in parenchyma bundle sheath (PBS) cells but they were not detected in the sieve element/companion cell complex of the phloem. Unlike LpSUT1 transcript levels which increased as a response to defoliation in source and sink tissues, LpSUT2 transcript levels were unaffected by defoliation and weakly expressed. Interestingly, sucrose transport by LpSUT2 was inhibited by fructose. LpSUT1 and LpSUT2 appeared to have different functions. LpSUT1 is proposed to play a key role in C storage and mobilization by allowing sucrose transport between PBS and mesophyll cells, depending on the plant C status. LpSUT2 could be involved in sucrose/fructose sensing at sub-cellular level. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  10. Reactive solute transport in an acidic stream: Experimental pH increase and simulation of controls on pH, aluminum, and iron

    Science.gov (United States)

    Broshears, R.E.; Runkel, R.L.; Kimball, B.A.; McKnight, Diane M.; Bencala, K.E.

    1996-01-01

    Solute transport simulations quantitatively constrained hydrologic and geochemical hypotheses about field observations of a pH modification in an acid mine drainage stream. Carbonate chemistry, the formation of solid phases, and buffering interactions with the stream bed were important factors in explaining the behavior of pH, aluminum, and iron. The precipitation of microcrystalline gibbsite accounted for the behavior of aluminum; precipitation of Fe(OH)3 explained the general pattern of iron solubility. The dynamic experiment revealed limitations on assumptions that reactions were controlled only by equilibrium chemistry. Temporal variation in relative rates of photoreduction and oxidation influenced iron behavior. Kinetic limitations on ferrous iron oxidation and hydrous oxide precipitation and the effects of these limitations on field filtration were evident. Kinetic restraints also characterized interaction between the water column and the stream bed, including sorption and desorption of protons from iron oxides at the sediment-water interface and post-injection dissolution of the precipitated aluminum solid phase.

  11. Guar gum solutions for improved delivery of iron particles in porous media (Part 2): Iron transport tests and modeling in radial geometry

    Science.gov (United States)

    Tosco, Tiziana; Gastone, Francesca; Sethi, Rajandrea

    2014-10-01

    In the present work column transport tests were performed in order to study the mobility of guar-gum suspensions of microscale zero-valent iron particles (MZVI) in porous media. The results were analyzed with the purpose of implementing a radial model for the design of full scale interventions. The transport tests were performed using several concentrations of shear thinning guar gum solutions as stabilizer (1.5, 3 and 4 g/l) and applying different flow rates (Darcy velocity in the range 1 · 10- 4 to 2 · 10- 3 m/s), representative of different distances from the injection point in the radial domain. Empirical relationships, expressing the dependence of the deposition and release parameters on the flow velocity, were derived by inverse fitting of the column transport tests using a modified version of E-MNM1D (Tosco and Sethi, 2010) and the user interface MNMs (www.polito.it/groundwater/software). They were used to develop a comprehensive transport model of MZVI suspensions in radial coordinates, called E-MNM1R, which takes into account the non Newtonian (shear thinning) rheological properties of the dispersant fluid and the porous medium clogging associated with filtration and sedimentation in the porous medium of both MZVI and guar gum residual undissolved particles. The radial model was run in forward mode to simulate the injection of MZVI dispersed in guar gum in conditions similar to those applied in the column transport tests. In a second stage, we demonstrated how the model can be used as a valid tool for the design and the optimization of a full scale intervention. The simulation results indicated that several concurrent aspects are to be taken into account for the design of a successful delivery of MZVI/guar gum slurries via permeation injection, and a compromise is necessary between maximizing the radius of influence of the injection and minimizing the injection pressure, to guarantee a sufficiently homogeneous distribution of the particles around the

  12. Construction of Listeria monocytogenes mutants with in-frame deletions in putative ATP-binding cassette (ABC) transporters and analysis of their growth under stress conditions

    Science.gov (United States)

    Listeria monocytogenes is a foodborne pathogen that is difficult to eliminate since it can survive under multiple stress conditions such as low pH and low temperature. Understanding its survival under stress conditions is important to control this pathogen in food. ABC transporters have been shown...

  13. 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

    Science.gov (United States)

    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

  14. Influence of permeability on nanoscale zero-valent iron particle transport in saturated homogeneous and heterogeneous porous media.

    Science.gov (United States)

    Strutz, Tessa J; Hornbruch, Götz; Dahmke, Andreas; Köber, Ralf

    2016-09-01

    Nanoscale zero-valent iron (NZVI) particles can be used for in situ groundwater remediation. The spatial particle distribution plays a very important role in successful and efficient remediation, especially in heterogeneous systems. Initial sand permeability (k 0) influences on spatial particle distributions were investigated and quantified in homogeneous and heterogeneous systems within the presented study. Four homogeneously filled column experiments and a heterogeneously filled tank experiment, using different median sand grain diameters (d 50), were performed to determine if NZVI particles were transported into finer sand where contaminants could be trapped. More NZVI particle retention, less particle transport, and faster decrease in k were observed in the column studies using finer sands than in those using coarser sands, reflecting a function of k 0. In heterogeneous media, NZVI particles were initially transported and deposited in coarse sand areas. Increasing the retained NZVI mass (decreasing k in particle deposition areas) caused NZVI particles to also be transported into finer sand areas, forming an area with a relatively homogeneous particle distribution and converged k values despite the different grain sizes present. The deposited-particle surface area contribution to the increasing of the matrix surface area (θ) was one to two orders of magnitude higher for finer than coarser sand. The dependency of θ on d 50 presumably affects simulated k changes and NZVI distributions in numerical simulations of NZVI injections into heterogeneous aquifers. The results implied that NZVI can in principle also penetrate finer layers.

  15. Zinc transporter ZIP14 functions in hepatic zinc, iron and glucose homeostasis during the innate immune response (endotoxemia.

    Directory of Open Access Journals (Sweden)

    Tolunay Beker Aydemir

    Full Text Available ZIP14 (slc39A14 is a zinc transporter induced in response to pro-inflammatory stimuli. ZIP14 induction accompanies the reduction in serum zinc (hypozincemia of acute inflammation. ZIP14 can transport Zn(2+ and non-transferrin-bound Fe(2+ in vitro. Using a Zip14(-/- mouse model we demonstrated that ZIP14 was essential for control of phosphatase PTP1B activity and phosphorylation of c-Met during liver regeneration. In the current studies, a global screening of ZIP transporter gene expression in response to LPS-induced endotoxemia was conducted. Following LPS, Zip14 was the most highly up-regulated Zip transcript in liver, but also in white adipose tissue and muscle. Using ZIP14(-/- mice we show that ZIP14 contributes to zinc absorption from the gastrointestinal tract directly or indirectly as zinc absorption was decreased in the KOs. In contrast, Zip14(-/- mice absorbed more iron. The Zip14 KO mice did not exhibit hypozincemia following LPS, but do have hypoferremia. Livers of Zip14-/- mice had increased transcript abundance for hepcidin, divalent metal transporter-1, ferritin and transferrin receptor-1 and greater accumulation of iron. The Zip14(-/- phenotype included greater body fat, hypoglycemia and higher insulin levels, as well as increased liver glucose and greater phosphorylation of the insulin receptor and increased GLUT2, SREBP-1c and FASN expression. The Zip14 KO mice exhibited decreased circulating IL-6 with increased hepatic SOCS-3 following LPS, suggesting SOCS-3 inhibited insulin signaling which produced the hypoglycemia in this genotype. The results are consistent with ZIP14 ablation yielding abnormal labile zinc pools which lead to increased SOCS-3 production through G-coupled receptor activation and increased cAMP production as well as signaled by increased pSTAT3 via the IL-6 receptor, which inhibits IRS 1/2 phosphorylation. Our data show the role of ZIP14 in the hepatocyte is multi-functional since zinc and iron trafficking are

  16. Overexpression of a novel Arabidopsis gene related to putative zinc-transporter genes from animals can lead to enhanced zinc resistance and accumulation.

    Science.gov (United States)

    van der Zaal, B J; Neuteboom, L W; Pinas, J E; Chardonnens, A N; Schat, H; Verkleij, J A; Hooykaas, P J

    1999-03-01

    We describe the isolation of an Arabidopsis gene that is closely related to the animal ZnT genes (Zn transporter). The protein encoded by the ZAT (Zn transporter of Arabidopsis thaliana) gene has 398 amino acid residues and is predicted to have six membrane-spanning domains. To obtain evidence for the postulated function of the Arabidopsis gene, transgenic plants with the ZAT coding sequence under control of the cauliflower mosaic virus 35S promoter were analyzed. Plants obtained with ZAT in the sense orientation exhibited enhanced Zn resistance and strongly increased Zn content in the roots under high Zn exposure. Antisense mRNA-producing plants were viable, with a wild-type level of Zn resistance and content, like plants expressing a truncated coding sequence lacking the C-terminal cytoplasmic domain of the protein. The availability of ZAT can lead to a better understanding of the mechanism of Zn homeostasis and resistance in plants.

  17. The maize glossy13 gene, cloned via BSR-Seq and Seq-walking encodes a putative ABC transporter required for the normal accumulation of epicuticular waxes.

    Directory of Open Access Journals (Sweden)

    Li Li

    Full Text Available Aerial plant surfaces are covered by epicuticular waxes that among other purposes serve to control water loss. Maize glossy mutants originally identified by their "glossy" phenotypes exhibit alterations in the accumulation of epicuticular waxes. By combining data from a BSR-Seq experiment and the newly developed Seq-Walking technology, GRMZM2G118243 was identified as a strong candidate for being the glossy13 gene. The finding that multiple EMS-induced alleles contain premature stop codons in GRMZM2G118243, and the one knockout allele of gl13, validates the hypothesis that gene GRMZM2G118243 is gl13. Consistent with this, GRMZM2G118243 is an ortholog of AtABCG32 (Arabidopsis thaliana, HvABCG31 (barley and OsABCG31 (rice, which encode ABCG subfamily transporters involved in the trans-membrane transport of various secondary metabolites. We therefore hypothesize that gl13 is involved in the transport of epicuticular waxes onto the surfaces of seedling leaves.

  18. Characterization of the putative amino acid transporter genes AtCAT2, 3 &4: the tonoplast localized AtCAT2 regulates soluble leaf amino acids.

    Science.gov (United States)

    Yang, Huaiyu; Krebs, Melanie; Stierhof, York-Dieter; Ludewig, Uwe

    2014-05-01

    The plant vacuole constitutes a large transient storage compartment for nutrients, proteins and metabolites, and is a major cellular sink for toxic waste compounds. Amino acids can cross the vacuolar membrane via specific transport proteins, which are molecularly not well characterized. Two members of a small subfamily of the cationic amino acid transporters, AtCAT2 and AtCAT4, were primarily localized at the tonoplast when tagged with GFP. The closely related AtCAT3, by contrast, was detected in the endoplasmic reticulum membrane. The exchange of a di-acidic motif at the carboxy-tail affected their sub-cellular localization, with larger effects visible in transiently transformed protoplasts compared to stably expressing plant lines. The genes have broad, partially overlapping tissue expression, with CAT2 dominating in most tissues. Loss-of-function mutants of individual CATs showed no visible phenotype under various conditions, but the overall tissue concentration of amino acids was increased in soil-grown cat2 mutants. The data suggest that CAT2 is a critical target of leaf amino acid concentrations and manipulation of this tonoplast transporter can significantly alter total tissue amino acid concentrations.

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

    Science.gov (United States)

    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.

  20. The capacity of Listeria monocytogenes mutants with in-frame deletions in putative ATP-binding cassette transporters to form biofilms and comparison with the wild type

    Directory of Open Access Journals (Sweden)

    Marina Ceruso

    2014-02-01

    Full Text Available Listeria monocytogenes (Lm is a food-borne pathogen responsible for human listeriosis, an invasive infection with high mortality rates. Lm has developed efficient strategies for survival under stress conditions such as starvation and wide variations in temperature, pH, and osmolarity. Therefore, Lm can survive in food under multiple stress conditions. Detailed studies to determine the mode of action of this pathogen for survival under stress conditions are important to control Lm in food. It has been shown that genes encoding for ATP-binding cassette (ABC transporters are induced in Lm in food, in particular under stress conditions. Previous studies showed that these genes are involved in sensitivity to nisin, acids, and salt. The aim of this study was to determine the involvement of some ABC transporters in biofilm formation. Therefore, deletion mutants of ABC transporter genes (LMOf2365_1875 and LMOf2365_1877 were created in Lm F2365, and then were compared to the wild type for their capacity to form biofilms. Lm strain F2365 was chosen as reference since the genome is fully sequenced and furthermore this strain is particularly involved in food-borne outbreaks of listeriosis. Our results showed that DLMOf2365_1875 had an increased capacity to form biofilms compared to the wild type, indicating that LMOf2365_1875 negatively regulates biofilm formation. A deeper knowledge on the ability to form biofilms in these mutants may help in the development of intervention strategies to control Lm in food and in the environment.

  1. The Capacity of Listeria Monocytogenes Mutants with In-Frame Deletions in Putative ATP-Binding Cassette Transporters to form Biofilms and Comparison with the Wild Type

    Science.gov (United States)

    Ceruso, Marina; Fratamico, Pina; Chirollo, Claudia; Taglialatela, Rosanna; Cortesi, Maria Luisa

    2014-01-01

    Listeria monocytogenes (Lm) is a food-borne pathogen responsible for human listeriosis, an invasive infection with high mortality rates. Lm has developed efficient strategies for survival under stress conditions such as starvation and wide variations in temperature, pH, and osmolarity. Therefore, Lm can survive in food under multiple stress conditions. Detailed studies to determine the mode of action of this pathogen for survival under stress conditions are important to control Lm in food. It has been shown that genes encoding for ATP-binding cassette (ABC) transporters are induced in Lm in food, in particular under stress conditions. Previous studies showed that these genes are involved in sensitivity to nisin, acids, and salt. The aim of this study was to determine the involvement of some ABC transporters in biofilm formation. Therefore, deletion mutants of ABC transporter genes (LMOf2365_1875 and LMOf2365_1877) were created in Lm F2365, and then were compared to the wild type for their capacity to form biofilms. Lm strain F2365 was chosen as reference since the genome is fully sequenced and furthermore this strain is particularly involved in food-borne outbreaks of listeriosis. Our results showed that ΔLMOf2365_1875 had an increased capacity to form biofilms compared to the wild type, indicating that LMOf2365_1875 negatively regulates biofilm formation. A deeper knowledge on the ability to form biofilms in these mutants may help in the development of intervention strategies to control Lm in food and in the environment. PMID:27800311

  2. Iron Deficiency Induces a Partial Inhibition of the Photosynthetic Electron Transport and a High Sensitivity to Light in the Diatom Phaeodactylum tricornutum

    Directory of Open Access Journals (Sweden)

    Mercedes Roncel

    2016-08-01

    Full Text Available Iron limitation is the major factor controlling phytoplankton growth in vast regions of the contemporary oceans. In this study, a combination of thermoluminescence, chlorophyll fluorescence and P700 absorbance measurements have been used to elucidate the effects of iron deficiency in the photosynthetic electron transport of the marine diatom Phaeodactylum tricornutum. Thermoluminescence was used to determine the effects of iron deficiency on Photosystem II activity. Excitation of iron-replete Phaeodactylum tricornutum cells with single turn-over flashes induced the appearance of thermoluminescence glow curves with two components with different peaks of temperature and contributions to the total signal intensity: the B band (23 ºC, 63%, and the AG band (40 ºC, 37%. Iron limitation did not significantly alter these bands, but induced a decrease of the total thermoluminescence signal. Far red excitation did not increase the amount of the AG band in iron-limited cells, as observed for iron-replete cells. The effect of iron deficiency on the photosystem I activity was also examined by measuring the changes in P700 redox state during illumination. The electron donation to photosystem I was substantially reduced in iron-deficient cells. This could be related with the important decline on cytochrome c6 content observed in these cells. Iron deficiency also induced a marked increase in light sensitivity in Phaeodactylum tricornutum cells. A drastic increase in the level of peroxidation of chloroplast lipids was detected in iron-deficient cells even when grown under standard conditions at low light intensity. Illumination with a light intensity of 300 E m-2 s-1 during different time periods caused a dramatic disappearance in thermoluminescence signal in cells grown under low iron concentration, this treatment not affecting to the signal in iron-replete cells. The results of this work suggest that iron deficiency induces partial blocking of the

  3. Transport and Retention Modelling of Iron Oxide Nanoparticles in Core Scale Porous Media for Electromagnetic Heating Well-Stimulation Optimization

    Science.gov (United States)

    Santoso, R. K.; Rachmat, S.; Putra, W. D. K.; Resha, A. H.; Hartowo, H.

    2017-07-01

    Understanding the transport and retention of iron oxide nanoparticles is critical in optimizing electromagnetic heating well stimulation. If the injected concentration or injection rate is too big, nanoparticles can build-up inside the pore throat, which can reduce the permeability of the reservoir. A numerical model has been created to describe the behavior of iron oxide nanoparticles in porous media. The model is coupling material balance equation and fluid flow in porous media equations. There are six parameters to be estimated through matching with experimental data: irreversible attachment rate, reversible attachment rate, irreversible attachment capacity, reversible attachment capacity, reversible detachment rate and permeability. All parameters were obtained directly through coreflooding result in previous study. We add Langmuir static isotherm test to limit the maximum adsorption capacity to provide a better estimation of concentration distribution. We use 1% NaCl solution as the base fluid and 45-50 mesh sand as the porous media. From the Langmuir static isotherm test, the maximum adsorption concentration is determined. Then, coreflooding is conducted using 10 ppm nanofluid and 12 cc/min injection rate. The proposed model is matched with the experimental data and its parameters are consistent with the maximum adsorption capacity provided from the test.

  4. Influence of yttrium iron garnet thickness and heater opacity on the nonlocal transport of electrically and thermally excited magnons

    Science.gov (United States)

    Shan, Juan; Cornelissen, Ludo J.; Vlietstra, Nynke; Ben Youssef, Jamal; Kuschel, Timo; Duine, Rembert A.; van Wees, Bart J.

    2016-11-01

    We studied the nonlocal transport behavior of both electrically and thermally excited magnons in yttrium iron garnet (YIG) as a function of its thickness. For electrically injected magnons, the nonlocal signals decrease monotonically as the YIG thickness increases. For the nonlocal behavior of the thermally generated magnons, or the nonlocal spin Seebeck effect (SSE), we observed a sign reversal which occurs at a certain heater-detector distance, and it is influenced by both the opacity of the YIG/heater interface and the YIG thickness. Our nonlocal SSE results can be qualitatively explained by the bulk-driven SSE mechanism together with the magnon diffusion model. Using a two-dimensional finite element model (2D-FEM), we estimated the bulk spin Seebeck coefficient of YIG at room temperature. The quantitative disagreement between the experimental and modeled results indicates more complex processes going on in addition to magnon diffusion and relaxation, especially close to the contacts.

  5. Atmospheric transport of mineral dust from the Indo-Gangetic Plain: Temporal variability, acid processing, and iron solubility

    Science.gov (United States)

    Srinivas, Bikkina; Sarin, M. M.; Rengarajan, R.

    2014-08-01

    transport of chemical constituents from the Indo-Gangetic Plain (IGP) to the Bay of Bengal is a conspicuous seasonal feature that occurs during the late NE-monsoon (December-March). With this perspective, aerosol composition and abundance of mineral dust have been studied during November 2009 to March 2010 from a sampling site (Kharagpur: 22.3°N, 87.3°E) in the IGP, representing the atmospheric outflow to the Bay of Bengal. The chemical composition of PM2.5 suggests the dominance of nss-SO42- (6.9-24.3 µg m-3); whereas the abundance of mineral dust varied from 3 to 18 µg m-3. The concentration of aerosol iron (FeTot) and its fractional solubility (Fews % = Fews/FeTot *100, where Fews is the water-soluble fraction of FeTot) varied from 60 to 1144 ng m-3 and from 6.7 to 26.5%, respectively. A striking similarity in the temporal variability of total inorganic acidity (TIA = NO3- + nss-SO42-) and Fews (%) provides evidence for acid processing of mineral dust (alluvium) during atmospheric transport from the IGP. The contribution of TIA to water-soluble inorganic species [(nss-SO42- + NO3-)/ΣWSIS], mass ratios of Ca/Al and Fe/Al, and abundance of dust (%) and Fews (%) in the IGP-outflow are similar to the aerosol composition over the Bay of Bengal. With the rapid increase in anthropogenic activities over south and south-east Asia, the enhanced fractional solubility of aerosol iron (attributed to acid processing of mineral dust) has implications to further increase in the air-sea deposition of Fe to the Ocean surface.

  6. Nano-scale zero valent iron transport in a variable aperture dolomite fracture and a glass fracture

    Science.gov (United States)

    Mondal, P.; Sleep, B. E.; Cui, Z.; Zhou, Z.

    2014-12-01

    Experiments and numerical simulations are being performed to understand the transport behavior of carboxymethyl cellulose polymer stabilized nano-scale zero valent iron (nZVI) in a variable aperture dolomite rock fracture and a variable aperture glass replica of a fractured slate. The rock fracture was prepared by artificially inducing a fracture in a dolomite block along a stylolite, and the glass fracture was prepared by creating molds with melted glass on two opposing sides of a fractured slate rock block. Both of the fractures were 0.28 m in length and 0.21 m in width. Equivalent hydraulic apertures are about 110 microns for the rock fracture and 250 microns for the glass replica fracture. Sodium bromide and lissamine green B (LGB) serve as conservative tracers in the rock fracture and glass replica fracture, respectively. A dark box set-up with a light source and digital camera is being used to visualize the LGB and CMC-nZVI movement in the glass fracture. Experiments are being performed to determine the effects of water specific discharge and CMC concentration on nZVI transport in the fractures. Transmission electron microscopy, dynamic light scattering, and UV-visual spectrophotometry were performed to determine the stability and characteristics of the CMC-nZVI mixture. The transport of bromide, LGB, CMC, and CMC-nZVI in both fractures is being evaluated through analysis of the effluent concentrations. Time-lapse images are also being captured for the glass fracture. Bromide, LGB, and CMC recoveries have exceeded 95% in both fractures. Significant channeling has been observed in the fractures for CMC transport due to viscous effects.

  7. Comparative genomics of iron-transporting systems in Bacillus cereus strains and impact of iron sources on growth and biofilm formation

    NARCIS (Netherlands)

    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 format

  8. The properties and transport phenomena in oxide films on iron, nickel, chromium and their alloys in aqueous environments

    Energy Technology Data Exchange (ETDEWEB)

    Laitinen, T.; Bojinov, M.; Betova, I.; Maekelae, K.; Saario, T. [VTT Manufacturing Technology, Espoo (Finland)

    1999-01-01

    The construction materials used in coolant systems in nuclear power plants become covered with oxide films as a result of exposure to the aqueous environment. The susceptibility of the materials to different forms of corrosion, as well as the extent of the incorporation of radioactive species on the surfaces of the primary circuit, are greatly influenced by the physical and chemical properties of these oxide films. The composition and characteristics of the oxide films in turn depend on the applied water chemistry. This work was undertaken in order to collect and evaluate the present views on the structure and behaviour of oxide films formed on iron- and nickel-based materials in aqueous environments. This survey should serve to recognise the areas in which more understanding and research effort is needed. The review begins with a discussion on the bulk oxides of iron, nickel and chromium, as well as their mixed oxides. In addition to bulk oxides, the structure and properties of oxide films forming on pure iron, nickel and chromium and on iron- and nickel-based engineering alloys are considered. General approaches to model the structure and growth of oxide films on metals are discussed in detail. The specific features of the oxide structures, properties and growth at high temperatures are presented with special focus on the relevance of existing models. Finally, the role of oxide films in localised corrosion, oxide breakdown pitting. Stress corrosion cracking and related phenomena is considered. The films formed on the surfaces of iron- and nickel-based alloys in high-temperature aqueous environments generally comprise two layers, i.e. the so-called duplex structure. The inner part is normally enriched in chromium and has a more compact structure, while the outer part is enriched in iron and has a cracked or porous structure. The information collected clearly indicates the effect of the chemical environment on the properties of oxide films growing on metal surfaces

  9. The chloroplast Rieske iron-sulfur protein. At the crossroad of electron transport and signal transduction.

    Science.gov (United States)

    de Vitry, Catherine; Ouyang, Yexin; Finazzi, Giovanni; Wollman, Francis-André; Kallas, Toivo

    2004-10-22

    We have addressed the functional and structural roles of three domains of the chloroplast Rieske iron-sulfur protein; that is, the flexible hinge that connects the transmembrane helix to the soluble cluster-bearing domain, the N-terminal stromal protruding domain, and the transmembrane helix. To this aim mutants were generated in the green alga Chlamydomonas reinhardtii. Their capacities to assemble the cytochrome b6f complex, perform plastoquinol oxidation, and signal redox-induced activation of the light-harvesting complex II kinase during state transition were tested in vivo. Deletion of one residue and extensions of up to five residues in the flexible hinge had no significant effect on complex accumulation or electron transfer efficiency. Deletion of three residues (Delta3G) dramatically decreased reaction rates by a factor of approximately 10. These data indicate that the chloroplast iron-sulfur protein-linking domain is much more flexible than that of its counterpart in mitochondria. Despite greatly slowed catalysis in the Delta3G mutant, there was no apparent delay in light-harvesting complex II kinase activation or state transitions. This indicates that conformational changes occurring in the Rieske protein did not represent a limiting step for kinase activation within the time scale tested. No phenotype could be associated with mutations in the N-terminal stromal-exposed domain. In contrast, the N17V mutation in the Rieske protein transmembrane helix resulted in a large decrease in the cytochrome f synthesis rate. This reveals that the Rieske protein transmembrane helix plays an active role in assembly-mediated control of cytochrome f synthesis. We propose a structural model to interpret this phenomenon based on the C. reinhardtii cytochrome b6f structure.

  10. Effects of symmetry and spin configuration on spin-dependent transport properties of iron-phthalocyanine-based devices

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Li-Ling [Institute of Super Microstructure and Ultrafast Process in Advanced Materials, School of Physics and Electronics, Central South University, Changsha 410083 (China); School of Science, Hunan University of Technology, Zhuzhou 412007 (China); Yang, Bing-Chu, E-mail: bingchuyang@csu.edu.cn; Li, Xin-Mei; Cao, Can [Institute of Super Microstructure and Ultrafast Process in Advanced Materials, School of Physics and Electronics, Central South University, Changsha 410083 (China); Long, Meng-Qiu, E-mail: mqlong@csu.edu.cn [Institute of Super Microstructure and Ultrafast Process in Advanced Materials, School of Physics and Electronics, Central South University, Changsha 410083 (China); Department of Physics and Materials Science, City University of Hong Kong, Hong Kong (China)

    2014-07-21

    Spin-dependent transport properties of nanodevices constructed by iron-phthalocyanine (FePc) molecule sandwiched between two zigzag graphene nanoribbon electrodes are studied using first-principles quantum transport calculations. The effects of the symmetry and spin configuration of electrodes have been taken into account. It is found that large magnetoresistance, large spin polarization, dual spin-filtering, and negative differential resistance (NDR) can coexist in these devices. Our results show that 5Z-FePc system presents well conductive ability in both parallel (P) and anti-parallel (AP) configurations. For 6Z-FePc-P system, spin filtering effect and large spin polarization can be found. A dual spin filtering and NDR can also be shown in 6Z-FePc-AP. Our studies indicate that the dual spin filtering effect depends on the orbitals symmetry of the energy bands and spin mismatching of the electrodes. And all the effects would open up possibilities for their applications in spin-valve, spin-filter as well as effective spin diode devices.

  11. Cell-surface signaling in Pseudomonas: stress responses, iron transport, and pathogenicity.

    Science.gov (United States)

    Llamas, María A; Imperi, Francesco; Visca, Paolo; Lamont, Iain L

    2014-07-01

    Membrane-spanning signaling pathways enable bacteria to alter gene expression in response to extracytoplasmic stimuli. Many such pathways are cell-surface signaling (CSS) systems, which are tripartite molecular devices that allow Gram-negative bacteria to transduce an extracellular stimulus into a coordinated transcriptional response. Typically, CSS systems are composed of the following: (1) an outer membrane receptor, which senses the extracellular stimulus; (2) a cytoplasmic membrane-spanning protein involved in signal transduction from the periplasm to the cytoplasm; and (3) an extracytoplasmic function (ECF) sigma factor that initiates expression of the stimulus-responsive gene(s). Members of genus Pseudomonas provide a paradigmatic example of how CSS systems contribute to the global control of gene expression. Most CSS systems enable self-regulated uptake of iron via endogenous (pyoverdine) or exogenous (xenosiderophores, heme, and citrate) carriers. Some are also implicated in virulence, biofilm formation, and cell-cell interactions. Incorporating insights from the well-characterized alginate regulatory circuitry, this review will illustrate common themes and variations at the level of structural and functional properties of Pseudomonas CSS systems. Control of the expression and activity of ECF sigma factors are central to gene regulation via CSS, and the variety of intrinsic and extrinsic factors influencing these processes will be discussed.

  12. Molecular evidence for the coordination of nitrogen and carbon metabolisms, revealed by a study on the transcriptional regulation of the agl3EFG operon that encodes a putative carbohydrate transporter in Streptomyces coelicolor.

    Science.gov (United States)

    Cen, Xu-Feng; Wang, Jing-Zhi; Zhao, Guo-Ping; Wang, Ying; Wang, Jin

    2016-03-18

    In the agl3EFGXYZ operon (SCO7167-SCO7162, abbreviated as agl3 operon) of Streptomyces coelicolor M145, agl3EFG genes encode a putative ABC-type carbohydrate transporter. The transcription of this operon has been proved to be repressed by Agl3R (SCO7168), a neighboring GntR-family regulator, and this repression can be released by growth on poor carbon sources. Here in this study, we prove that the transcription of agl3 operon is also directly repressed by GlnR, a central regulator governing the nitrogen metabolism in S. coelicolor. The electrophoretic mobility shift assay (EMSA) employing the agl3 promoter and mixtures of purified recombinant GlnR and Agl3R indicates that GlnR and Agl3R bind to different DNA sequences within the promoter region of agl3 operon, which is further confirmed by the DNase I footprinting assay. As Agl3R and GlnR have been demonstrated to sense the extracellular carbon and nitrogen supplies, respectively, it is hypothesized that the transcription of agl3 operon is stringently governed by the availabilities of extracellular carbon and nitrogen sources. Consistent with the hypothesis, the agl3 operon is further found to be derepressed only under the condition of poor carbon and rich nitrogen supplies, when both regulators are inactivated. It is believed that activation of the expression of agl3 operon may facilitate the absorption of extracellular carbohydrates to balance the ratio of intracellular carbon to nitrogen.

  13. Phase Stability and Stoichiometry in Thin Film Iron Pyrite: Impact on Electronic Transport Properties.

    Science.gov (United States)

    Zhang, Xin; Scott, Tom; Socha, Tyler; Nielsen, David; Manno, Michael; Johnson, Melissa; Yan, Yuqi; Losovyj, Yaroslav; Dowben, Peter; Aydil, Eray S; Leighton, Chris

    2015-07-01

    The use of pyrite FeS2 as an earth-abundant, low-cost, nontoxic thin film photovoltaic hinges on improved understanding and control of certain physical and chemical properties. Phase stability, phase purity, stoichiometry, and defects, are central in this respect, as they are frequently implicated in poor solar cell performance. Here, phase-pure polycrystalline pyrite FeS2 films, synthesized by ex situ sulfidation, are subject to systematic reduction by vacuum annealing (to 550 °C) to assess phase stability, stoichiometry evolution, and their impact on transport. Bulk probes reveal the onset of pyrrhotite (Fe(1-δ)S) around 400 °C, rapidly evolving into the majority phase by 425 °C. This is supported by X-ray photoelectron spectroscopy on (001) crystals, revealing surface Fe(1-δ)S formation as low as 160 °C, with rapid growth near 400 °C. The impact on transport is dramatic, with Fe(1-δ)S minority phases leading to a crossover from diffusive transport to hopping (due to conductive Fe(1-δ)S nanoregions in an FeS2 matrix), followed by metallicity when Fe(1-δ)S dominates. Notably, the crossover to hopping leads to an inversion of the sign, and a large decrease in magnitude of the Hall coefficient. By tracking resistivity, magnetotransport, magnetization, and structural/chemical parameters vs annealing, we provide a detailed picture of the evolution in properties with stoichiometry. A strong propensity for S-deficient minority phase formation is found, with no wide window where S vacancies control the FeS2 carrier density. These findings have important implications for FeS2 solar cell development, emphasizing the need for (a) nanoscale chemical homogeneity, and (b) caution in interpreting carrier types and densities.

  14. 49 CFR 192.373 - Service lines: Cast iron and ductile iron.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Service lines: Cast iron and ductile iron. 192.373... Regulators, and Service Lines § 192.373 Service lines: Cast iron and ductile iron. (a) Cast or ductile iron... cast iron pipe or ductile iron pipe is installed for use as a service line, the part of the...

  15. Scallop DMT functions as a Ca2+ transporter.

    Science.gov (United States)

    Toyohara, Haruhiko; Yamamoto, Sayuri; Hosoi, Masatomi; Takagi, Masaya; Hayashi, Isao; Nakao, Kenji; Kaneko, Shuji

    2005-05-01

    We identified a DMT (divalent metal transporter) homologous protein that functions as a Ca(2+) transporter. Scallop DMT cDNA encodes a 539-amino-acid protein with 12 putative membrane-spanning domains and has a consensus transport motif in the fourth extracellular loop. Since its mRNA is significantly expressed in the gill and intestine, it is assumed that scallop DMT transports Ca(2+) from seawater by the gill and from food by the intestine. Scallop DMT lacks the iron-responsive element commonly found in iron-regulatory proteins, suggesting that it is free of the post-transcriptional regulation from intracellular Fe(2+) concentration. Scallop DMT distinctly functions as a Ca(2+) transporter unlike other DMTs, however, it also transports Fe(2+) and Cd(2+) similar to them.

  16. Splicing factor SR34b mutation reduces cadmium tolerance in Arabidopsis by regulating iron-regulated transporter 1 gene

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wentao; Du, Bojing; Liu, Di; Qi, Xiaoting, E-mail: qixiaoting@cnu.edu.cn

    2014-12-12

    Highlights: • Arabidopsis splicing factor SR34b gene is cadmium-inducible. • SR34b T-DNA insertion mutant is sensitive to cadmium due to high cadmium uptake. • SR34b is a regulator of cadmium transporter IRT1 at the posttranscription level. • These results highlight the roles of splicing factors in cadmium tolerance of plant. - Abstract: Serine/arginine-rich (SR) proteins are important splicing factors. However, the biological functions of plant SR proteins remain unclear especially in abiotic stresses. Cadmium (Cd) is a non-essential element that negatively affects plant growth and development. In this study, we provided clear evidence for SR gene involved in Cd tolerance in planta. Systemic expression analysis of 17 Arabidopsis SR genes revealed that SR34b is the only SR gene upregulated by Cd, suggesting its potential roles in Arabidopsis Cd tolerance. Consistent with this, a SR34b T-DNA insertion mutant (sr34b) was moderately sensitive to Cd, which had higher Cd{sup 2+} uptake rate and accumulated Cd in greater amounts than wild-type. This was due to the altered expression of iron-regulated transporter 1 (IRT1) gene in sr34b mutant. Under normal growth conditions, IRT1 mRNAs highly accumulated in sr34b mutant, which was a result of increased stability of IRT1 mRNA. Under Cd stress, however, sr34b mutant plants had a splicing defect in IRT1 gene, thus reducing the IRT1 mRNA accumulation. Despite of this, sr34b mutant plants still constitutively expressed IRT1 proteins under Cd stress, thereby resulting in Cd stress-sensitive phenotype. We therefore propose the essential roles of SR34b in posttranscriptional regulation of IRT1 expression and identify it as a regulator of Arabidopsis Cd tolerance.

  17. TonB-dependent transporters and their occurrence in cyanobacteria.

    Science.gov (United States)

    Mirus, Oliver; Strauss, Sascha; Nicolaisen, Kerstin; von Haeseler, Arndt; Schleiff, Enrico

    2009-10-12

    Different iron transport systems evolved in Gram-negative bacteria during evolution. Most of the transport systems depend on outer membrane localized TonB-dependent transporters (TBDTs), a periplasma-facing TonB protein and a plasma membrane localized machinery (ExbBD). So far, iron chelators (siderophores), oligosaccharides and polypeptides have been identified as substrates of TBDTs. For iron transport, three uptake systems are defined: the lactoferrin/transferrin binding proteins, the porphyrin-dependent transporters and the siderophore-dependent transporters. However, for cyanobacteria almost nothing is known about possible TonB-dependent uptake systems for iron or other substrates. We have screened all publicly available eubacterial genomes for sequences representing (putative) TBDTs. Based on sequence similarity, we identified 195 clusters, where elements of one cluster may possibly recognize similar substrates. For Anabaena sp. PCC 7120 we identified 22 genes as putative TBDTs covering almost all known TBDT subclasses. This is a high number of TBDTs compared to other cyanobacteria. The expression of the 22 putative TBDTs individually depends on the presence of iron, copper or nitrogen. We exemplified on TBDTs the power of CLANS-based classification, which demonstrates its importance for future application in systems biology. In addition, the tentative substrate assignment based on characterized proteins will stimulate the research of TBDTs in different species. For cyanobacteria, the atypical dependence of TBDT gene expression on different nutrition points to a yet unknown regulatory mechanism. In addition, we were able to clarify a hypothesis of the absence of TonB in cyanobacteria by the identification of according sequences.

  18. TonB-dependent transporters and their occurrence in cyanobacteria

    Directory of Open Access Journals (Sweden)

    von Haeseler Arndt

    2009-10-01

    Full Text Available Abstract Background Different iron transport systems evolved in Gram-negative bacteria during evolution. Most of the transport systems depend on outer membrane localized TonB-dependent transporters (TBDTs, a periplasma-facing TonB protein and a plasma membrane localized machinery (ExbBD. So far, iron chelators (siderophores, oligosaccharides and polypeptides have been identified as substrates of TBDTs. For iron transport, three uptake systems are defined: the lactoferrin/transferrin binding proteins, the porphyrin-dependent transporters and the siderophore-dependent transporters. However, for cyanobacteria almost nothing is known about possible TonB-dependent uptake systems for iron or other substrates. Results We have screened all publicly available eubacterial genomes for sequences representing (putative TBDTs. Based on sequence similarity, we identified 195 clusters, where elements of one cluster may possibly recognize similar substrates. For Anabaena sp. PCC 7120 we identified 22 genes as putative TBDTs covering almost all known TBDT subclasses. This is a high number of TBDTs compared to other cyanobacteria. The expression of the 22 putative TBDTs individually depends on the presence of iron, copper or nitrogen. Conclusion We exemplified on TBDTs the power of CLANS-based classification, which demonstrates its importance for future application in systems biology. In addition, the tentative substrate assignment based on characterized proteins will stimulate the research of TBDTs in different species. For cyanobacteria, the atypical dependence of TBDT gene expression on different nutrition points to a yet unknown regulatory mechanism. In addition, we were able to clarify a hypothesis of the absence of TonB in cyanobacteria by the identification of according sequences.

  19. Maternal-fetal iron status and the relationship between it and the expression of placental iron transporters%母-胎铁状态及与胎盘铁转运因子表达的关系

    Institute of Scientific and Technical Information of China (English)

    李燕琴; 贾志; 白斌; 颜虹; 张耀辉

    2012-01-01

    目的 对母-胎铁营养之间的关系及其与胎盘铁转运因子表达的关系进行分析,为进一步理解母-胎铁营养关系及其调节机制提供线索.方法 以健康足月的40名不同铁营养状态孕妇为研究对象,采集分娩时母亲静脉血及脐血、胎盘,进行血液学检测及Western Blot和实时定量PCR检测.结果 胎儿的各项血液学参数均高于母亲.母亲血红蛋白浓度与胎儿的红细胞计数有显著相关性(r=0.504,P<0.05);母亲血红蛋白浓度和胎盘组织铁蛋白的蛋白表达呈显著相关性(r=0.436,P<0.05).其余各指标之间均无明显的相关性.结论 母-胎铁状态之间及其与胎盘铁转运因子的表达之间仅部分具有一定的相关性.%Objective To analyze the correlation between-maternal and fetal iron status and the relationship between maternd-fetal iron status and the expression of placental iron transporters, so as to provide clue for further understanding of maternal-fetal iron nutrition and its regulatory mechanism. Methods Forty healthy full-term pregnant women with different iron nutrition status were chosen for the research. Maternal vein blood, umbilical cord blood and placental tissues were collected at the delivery. Routine blood test, Western Blot and realtime PCR test were conducted in this study. Results All hematological parameters of umbilical cord blood were higher than those of maternal blood. The maternal hemoglobin level was significantly correlated with fetal red blood count( r = 0. 504, P <0. 05 ). There were also significant correlations between maternal hemoglobin level and the protein expression of placental ferritin( r = 0. 436, P < 0. 05 ). The other indexes showed no significant correlation. Conclusion Only some of parameters of maternal-fetal iron status and placental iron transporters are correlated.

  20. Effect of sulfur addition on the transport properties of semiconducting iron phosphate glasses

    Energy Technology Data Exchange (ETDEWEB)

    El-Desoky, M.M. [Physics Department, Faculty of Science, Suez Canal University, Suez (Egypt); Ibrahim, F.A. [Department of Physics, Faculty of Education, Suez Canal University, Al-Arish (Egypt); Hassaan, M.Y. [Department of Physics, Faculty of Science, Al-Azhar University, Nasr City, 11884 Cairo (Egypt)

    2011-08-15

    The present paper focuses on a quantitative analysis of the metallic and semiconducting behavior of electrical resistivity in La{sub 0.91}Rb{sub 0.06}Mn{sub 0.94}O{sub 3} manganites. The contribution of inherent low-frequency acoustic phonons as well as high-frequency optical phonons, to the electron-phonon resistivity is estimated following Bloch-Gruneisen model. The computed phonon resistivity is compared with that of reported metallic resistivity, accordingly {rho}diff. [{rho}exp. - {l_brace}{rho}0 + {rho}e-ph (={rho}ac + {rho}op){r_brace}] have been analysed through electron-electron scattering. Also, the difference can be varies linearly with T{sup 4.5} in accordance with the electron-magnon scattering in the double exchange process. The results reveal important aspects transport mechanism as well as point out that it is not only dominated by electron-phonon scattering, but also by electron-electron and electron-magnon scattering process. Alternatively, in high temperature regime (T {>=} T{sub P}) the semiconducting nature is discussed with Mott's variable range hopping (VRH) and small polaron conduction (SPC) model. (authors)

  1. Distal transport of dissolved hydrothermal iron in the deep South Pacific Ocean.

    Science.gov (United States)

    Fitzsimmons, Jessica N; Boyle, Edward A; Jenkins, William J

    2014-11-25

    Until recently, hydrothermal vents were not considered to be an important source to the marine dissolved Fe (dFe) inventory because hydrothermal Fe was believed to precipitate quantitatively near the vent site. Based on recent abyssal dFe enrichments near hydrothermal vents, however, the leaky vent hypothesis [Toner BM, et al. (2012) Oceanography 25(1):209-212] argues that some hydrothermal Fe persists in the dissolved phase and contributes a significant flux of dFe to the global ocean. We show here the first, to our knowledge, dFe (hydrothermally derived based on its correlation with primordial (3)He and dissolved Mn (dFe:(3)He of 0.9-2.7 × 10(6)). Given the known sites of hydrothermal venting in these regions, this dFe must have been transported thousands of kilometers away from its vent site to reach our sampling stations. Additionally, changes in the size partitioning of the hydrothermal dFe between soluble (vents indicate that dFe transformations continue to occur far from the vent source. This study confirms that although the southern East Pacific Rise only leaks 0.02-1% of total Fe vented into the abyssal Pacific, this dFe persists thousands of kilometers away from the vent source with sufficient magnitude that hydrothermal vents can have far-field effects on global dFe distributions and inventories (≥3% of global aerosol dFe input).

  2. Iron and zinc complexation in wild-type and ferritin-expressing wheat grain: implications for mineral transport into developing grain

    DEFF Research Database (Denmark)

    Neal, Andrew L; Geraki, Kalotina; Borg, Søren

    2013-01-01

    We have used synchrotron-based X-ray fluorescence and absorption techniques to establish both metal distribution and complexation in mature wheat grains. In planta, extended X-ray absorption fine structure (EXAFS) spectroscopy reveals iron phytate and zinc phytate structures in aleurone cells...... of ferritin-expressing grains is quite different from that in wild-type grain. This may explain why the raised levels of minerals transported to the developing grain accumulate within the crease region of the transgenic grain....

  3. Placental iron uptake and its regulation

    NARCIS (Netherlands)

    M. Bierings (Marc)

    1989-01-01

    textabstractIron transport in pregnancy is an active one-way process, from mother to fetus. Early in gestation fetal iron needs are low, and so is trans-placental transport, but as erythropoiesis develops, rising fetal iron needs are met by trans-placental iron transport. Apparently, the fetus is pr

  4. Minor effect of physical size sorting on iron solubility of transported mineral dust

    Directory of Open Access Journals (Sweden)

    Z. B. Shi

    2011-05-01

    Full Text Available Observations show that the fractional solubility of Fe (FS-Fe, ratio of dissolved to total Fe in dust aerosol increases dramatically from ~0.1% in regions of high dust mass concentration to 80% in remote regions where concentrations are low. Here, we combined laboratory geochemical measurements with global aerosol model simulations to test the hypothesis that the increase in FS-Fe is due to physical size sorting during transport. We determined the FS-Fe and fractional solubility of Al (FS-Al in size-fractionated dust generated from two representative soil samples collected from known Saharan dust source regions using a customized dust re-suspension and collection system. The results show that the FS-Fe is size-dependent and ranges from 0.1–0.3 % in the coarse size fractions (>1 μm to ~0.2–0.8 % in the fine size fractions (<1 μm. The FS-Al shows a similar size distribution to that of FS-Fe. The size-resolved FS-Fe data were then combined with simulated dust mass concentration and size distribution data from a global aerosol model, GLOMAP, to calculate the FS-Fe of dust aerosol over the tropical and subtropical North Atlantic Ocean. We find that the calculated FS-Fe in the dust aerosol increases systematically from ~0.1 % at high dust mass concentrations (e.g., >100 μg m−3 to ~0.2 % at low concentrations (<100 μg m−3 due to physical size sorting (i.e., particle gravitational settling. These values are one to two orders of magnitude smaller than those observed on cruises across the tropical and sub-tropical North Atlantic Ocean under an important pathway of Saharan dust plumes for similar dust mass concentrations. Even when the FS-Fe of sub-micrometer size fractions (0.18–0.32 μm, 0.32–0.56 μm, and 0.56–1.0 μm in the model is increased by a factor of 10 over the measured values, the calculated FS-Fe of the dust is still more than an order of magnitude lower than that measured in the field. Therefore, the

  5. Minor effect of physical size sorting on iron solubility of transported mineral dust

    Directory of Open Access Journals (Sweden)

    Z. B. Shi

    2011-08-01

    Full Text Available Observations show that the fractional solubility of Fe (FS-Fe, percentage of dissolved to total Fe in dust aerosol increases considerably from 0.1 % in regions of high dust mass concentration to 80 % in remote regions where concentrations are low. Here, we combined laboratory geochemical measurements with global aerosol model simulations to test the hypothesis that the increase in FS-Fe is due to physical size sorting during transport. We determined the FS-Fe and fractional solubility of Al (FS-Al in size-fractionated dust generated from two representative soil samples collected from known Saharan dust source regions using a customized dust re-suspension and collection system. The results show that the FS-Fe is size-dependent and ranges from 0.1–0.3 % in the coarse size fractions (>1 μm to ~0.2–0.8 % in the fine size fractions (<1 μm. The FS-Al shows a similar size distribution to that of the FS-Fe. The size-resolved FS-Fe data were then combined with simulated dust mass concentration and size distribution data from a global aerosol model, GLOMAP, to calculate the FS-Fe of dust aerosol over the tropical and subtropical North Atlantic Ocean. We find that the calculated FS-Fe in the dust aerosol increases systematically from ~0.1 % at high dust mass concentrations (e.g., >100 μg m−3 to ~0.2 % at low concentrations (<100 μg m–3 due to physical size sorting (i.e., particle gravitational settling. These values are one to two orders of magnitude smaller than those observed on cruises across the tropical and sub-tropical North Atlantic Ocean under an important pathway of Saharan dust plumes for similar dust mass concentrations. Even when the FS-Fe of sub-micrometer size fractions (0.18–0.32 μm, 0.32–0.56 μm, and 0.56–1.0 μm in the model is increased by a factor of 10 over the measured values, the calculated FS-Fe of the dust is still more than an order of magnitude lower than that measured in the field

  6. Iron deficiency anemia

    OpenAIRE

    Naigamwalla, Dinaz Z.; Webb, Jinelle A.; Giger, Urs

    2012-01-01

    Iron is essential to virtually all living organisms and is integral to multiple metabolic functions. The most important function is oxygen transport in hemoglobin. Iron deficiency anemia in dogs and cats is usually caused by chronic blood loss and can be discovered incidentally as animals may have adapted to the anemia. Severe iron deficiency is characterized by a microcytic, hypochromic, potentially severe anemia with a variable regenerative response. Iron metabolism and homeostasis will be ...

  7. Identifying the Genes Responsible for Iron-Limited Condition in Riemerella anatipestifer CH-1 through RNA-Seq-Based Analysis

    Directory of Open Access Journals (Sweden)

    MaFeng Liu

    2017-01-01

    Full Text Available One of the important elements for most bacterial growth is iron, the bioavailability of which is limited in hosts. Riemerella anatipestifer (R. anatipestifer, RA, an important duck pathogen, requires iron to live. However, the genes involved in iron metabolism and the mechanisms of iron transport are largely unknown. Here, we investigated the transcriptomic effects of iron limitation condition on R. anatipestifer CH-1 using the RNA-Seq and RNA-Seq-based analysis. Data analysis revealed genes encoding functions related to iron homeostasis, including a number of putative TonB-dependent receptor systems, a HmuY-like protein-dependent hemin (an iron-containing porphyrin uptake system, a Feo system, a gene cluster related to starch utilization, and genes encoding hypothetical proteins that were significantly upregulated in response to iron limitation. Compared to the number of upregulated genes, more genes were significantly downregulated in response to iron limitation. The downregulated genes mainly encoded a number of outer membrane receptors, DNA-binding proteins, phage-related proteins, and many hypothetical proteins. This information suggested that RNA-Seq-based analysis in iron-limited medium is an effective and fast method for identifying genes involved in iron uptake in R. anatipestifer CH-1.

  8. 49 CFR 192.489 - Remedial measures: Cast iron and ductile iron pipelines.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Remedial measures: Cast iron and ductile iron... for Corrosion Control § 192.489 Remedial measures: Cast iron and ductile iron pipelines. (a) General graphitization. Each segment of cast iron or ductile iron pipe on which general graphitization is found to...

  9. Silencing the Menkes Copper-Transporting ATPase (Atp7a) Gene in Rat Intestinal Epithelial (IEC-6) Cells Increases Iron Flux via Transcriptional Induction of Ferroportin 1 (Fpn1)123

    Science.gov (United States)

    Gulec, Sukru; Collins, James F.

    2014-01-01

    The Menkes copper-transporting ATPase (Atp7a) gene is induced in rat duodenum during iron deficiency, consistent with copper accumulation in the intestinal mucosa and liver. To test the hypothesis that ATP7A influences intestinal iron metabolism, the Atp7a gene was silenced in rat intestinal epithelial (IEC-6) cells using short hairpin RNA (shRNA) technology. Perturbations in intracellular copper homeostasis were noted in knockdown cells, consistent with the dual roles of ATP7A in pumping copper into the trans-Golgi (for cuproenzyme synthesis) and exporting copper from cells. Intracellular iron concentrations were unaffected by Atp7a knockdown. Unexpectedly, however, vectorial iron (59Fe) transport increased (∼33%) in knockdown cells grown in bicameral inserts and increased further (∼70%) by iron deprivation (compared with negative control shRNA-transfected cells). Additional experiments were designed to elucidate the molecular mechanism of increased transepithelial iron flux. Enhanced iron uptake by knockdown cells was associated with increased expression of a ferrireductase (duodenal cytochrome b) and activity of a cell-surface ferrireductase. Increased iron efflux from knockdown cells was likely mediated via transcriptional activation of the ferroportin 1 gene (by an unknown mechanism). Moreover, Atp7a knockdown significantly attenuated expression of an iron oxidase [hephaestin (HEPH); by ∼80%] and membrane ferroxidase activity (by ∼50%). Cytosolic ferroxidase activity, however, was retained in knockdown cells (75% of control cells), perhaps compensating for diminished HEPH activity. This investigation has thus documented alterations in iron homeostasis associated with Atp7a knockdown in enterocyte-like cells. Alterations in copper transport, trafficking, or distribution may underlie the increase in transepithelial iron flux noted when ATP7A activity is diminished. PMID:24174620

  10. Silencing the Menkes copper-transporting ATPase (Atp7a) gene in rat intestinal epithelial (IEC-6) cells increases iron flux via transcriptional induction of ferroportin 1 (Fpn1).

    Science.gov (United States)

    Gulec, Sukru; Collins, James F

    2014-01-01

    The Menkes copper-transporting ATPase (Atp7a) gene is induced in rat duodenum during iron deficiency, consistent with copper accumulation in the intestinal mucosa and liver. To test the hypothesis that ATP7A influences intestinal iron metabolism, the Atp7a gene was silenced in rat intestinal epithelial (IEC-6) cells using short hairpin RNA (shRNA) technology. Perturbations in intracellular copper homeostasis were noted in knockdown cells, consistent with the dual roles of ATP7A in pumping copper into the trans-Golgi (for cuproenzyme synthesis) and exporting copper from cells. Intracellular iron concentrations were unaffected by Atp7a knockdown. Unexpectedly, however, vectorial iron ((59)Fe) transport increased (∼33%) in knockdown cells grown in bicameral inserts and increased further (∼70%) by iron deprivation (compared with negative control shRNA-transfected cells). Additional experiments were designed to elucidate the molecular mechanism of increased transepithelial iron flux. Enhanced iron uptake by knockdown cells was associated with increased expression of a ferrireductase (duodenal cytochrome b) and activity of a cell-surface ferrireductase. Increased iron efflux from knockdown cells was likely mediated via transcriptional activation of the ferroportin 1 gene (by an unknown mechanism). Moreover, Atp7a knockdown significantly attenuated expression of an iron oxidase [hephaestin (HEPH); by ∼80%] and membrane ferroxidase activity (by ∼50%). Cytosolic ferroxidase activity, however, was retained in knockdown cells (75% of control cells), perhaps compensating for diminished HEPH activity. This investigation has thus documented alterations in iron homeostasis associated with Atp7a knockdown in enterocyte-like cells. Alterations in copper transport, trafficking, or distribution may underlie the increase in transepithelial iron flux noted when ATP7A activity is diminished.

  11. Iron-refractory iron deficiency anemia.

    Science.gov (United States)

    Yılmaz Keskin, Ebru; Yenicesu, İdil

    2015-03-05

    Iron is essential for life because it is indispensable for several biological reactions, such as oxygen transport, DNA synthesis, and cell proliferation. Over the past few years, our understanding of iron metabolism and its regulation has changed dramatically. New disorders of iron metabolism have emerged, and the role of iron as a cofactor in other disorders has begun to be recognized. The study of genetic conditions such as hemochromatosis and iron-refractory iron deficiency anemia (IRIDA) has provided crucial insights into the molecular mechanisms controlling iron homeostasis. In the future, these advances may be exploited to improve treatment of both genetic and acquired iron disorders. IRIDA is caused by mutations in TMPRSS6, the gene encoding matriptase-2, which downregulates hepcidin expression under conditions of iron deficiency. The typical features of this disorder are hypochromic, microcytic anemia with a very low mean corpuscular volume of erythrocytes, low transferrin saturation, no (or inadequate) response to oral iron, and only a partial response to parenteral iron. In contrast to classic iron deficiency anemia, serum ferritin levels are usually low-normal, and serum or urinary hepcidin levels are inappropriately high for the degree of anemia. Although the number of cases reported thus far in the literature does not exceed 100, this disorder is considered the most common of the "atypical" microcytic anemias. The aim of this review is to share the current knowledge on IRIDA and increase awareness in this field.

  12. Iron-Refractory Iron Deficiency Anemia

    Science.gov (United States)

    Yılmaz Keskin, Ebru; Yenicesu, İdil

    2015-01-01

    Iron is essential for life because it is indispensable for several biological reactions, such as oxygen transport, DNA synthesis, and cell proliferation. Over the past few years, our understanding of iron metabolism and its regulation has changed dramatically. New disorders of iron metabolism have emerged, and the role of iron as a cofactor in other disorders has begun to be recognized. The study of genetic conditions such as hemochromatosis and iron-refractory iron deficiency anemia (IRIDA) has provided crucial insights into the molecular mechanisms controlling iron homeostasis. In the future, these advances may be exploited to improve treatment of both genetic and acquired iron disorders. IRIDA is caused by mutations in TMPRSS6, the gene encoding matriptase-2, which downregulates hepcidin expression under conditions of iron deficiency. The typical features of this disorder are hypochromic, microcytic anemia with a very low mean corpuscular volume of erythrocytes, low transferrin saturation, no (or inadequate) response to oral iron, and only a partial response to parenteral iron. In contrast to classic iron deficiency anemia, serum ferritin levels are usually low-normal, and serum or urinary hepcidin levels are inappropriately high for the degree of anemia. Although the number of cases reported thus far in the literature does not exceed 100, this disorder is considered the most common of the “atypical” microcytic anemias. The aim of this review is to share the current knowledge on IRIDA and increase awareness in this field. PMID:25805669

  13. Intestinal Iron Homeostasis and Colon Tumorigenesis

    Directory of Open Access Journals (Sweden)

    Yatrik M. Shah

    2013-06-01

    Full Text Available Colorectal cancer (CRC is the third most common cause of cancer-related deaths in industrialized countries. Understanding the mechanisms of growth and progression of CRC is essential to improve treatment. Iron is an essential nutrient for cell growth. Iron overload caused by hereditary mutations or excess dietary iron uptake has been identified as a risk factor for CRC. Intestinal iron is tightly controlled by iron transporters that are responsible for iron uptake, distribution, and export. Dysregulation of intestinal iron transporters are observed in CRC and lead to iron accumulation in tumors. Intratumoral iron results in oxidative stress, lipid peroxidation, protein modification and DNA damage with consequent promotion of oncogene activation. In addition, excess iron in intestinal tumors may lead to increase in tumor-elicited inflammation and tumor growth. Limiting intratumoral iron through specifically chelating excess intestinal iron or modulating activities of iron transporter may be an attractive therapeutic target for CRC.

  14. The influence of hydrous ferric oxide, earthworms, and a hypertolerant plant on arsenic and iron bioavailability, fate, and transport in soils.

    Science.gov (United States)

    Maki, Benjamin C; Hodges, Kathryn R; Ford, Scott C; Sofield, Ruth M

    2016-10-24

    Historic applications of lead arsenate pesticides and smelting activities have resulted in elevated concentrations of arsenic in Washington State soils. For example, old orchard topsoils in Washington have concentrations reaching upwards of 350 mg As/kg soil with an estimated 187,590 acres of arsenic contamination from pesticide application alone. Iron oxides have been indicated as a key factor in modulating the fate and transport of arsenic in the soil environment. We employed a factorial design to investigate the role of a specific iron oxide, hydrous ferric oxide (HFO), and terrestrial organisms on the mobility, bioavailability, and fate of arsenic and iron in locally collected soils. Earthworms in soils amended with both arsenic and HFO had 47.2 % lower arsenic tissue concentrations compared to those in soils only amended with arsenic. Similarly, arsenic leachate concentrations and plant tissue concentrations were lower when HFO was present, although this was with a reduced magnitude and was not consistently significant. A lack of significance of HFO in three of the linear models for leachate and plant bioavailability, however, indicates that the role of HFO in arsenic mobility, bioavailability, and fate is more complicated than can be explained by the simple addition or not of HFO. For example, our analyses showed that earthworms decreased pH and increased bioavailability for both arsenic and iron as demonstrated by increases in leachate and plant tissue concentrations. The mechanisms for this could include a biotransformation of earthworm-ingested arsenic combined with an earthworm-induced change in pH. We also found that arsenic amendments increased the mobility and bioavailability of iron, evidenced by increased iron concentrations in earthworms, plants, and leachate. A mechanistic explanation for this change in bioavailability is not readily apparent but does support a need for more work on bioavailability when mixtures are present. From these results

  15. 49 CFR 192.487 - Remedial measures: Distribution lines other than cast iron or ductile iron lines.

    Science.gov (United States)

    2010-10-01

    ... cast iron or ductile iron lines. 192.487 Section 192.487 Transportation Other Regulations Relating to... iron or ductile iron lines. (a) General corrosion. Except for cast iron or ductile iron pipe, each... the purpose of this paragraph. (b) Localized corrosion pitting. Except for cast iron or ductile...

  16. Magnetic resonance imaging reveals detailed spatial and temporal distribution of iron-based nanoparticles transported through water-saturated porous media

    Science.gov (United States)

    Cuny, Laure; Herrling, Maria Pia; Guthausen, Gisela; Horn, Harald; Delay, Markus

    2015-11-01

    The application of engineered nanoparticles (ENP) such as iron-based ENP in environmental systems or in the human body inevitably raises the question of their mobility. This also includes aspects of product optimization and assessment of their environmental fate. Therefore, the key aim was to investigate the mobility of iron-based ENP in water-saturated porous media. Laboratory-scale transport experiments were conducted using columns packed with quartz sand as model solid phase. Different superparamagnetic iron oxide nanoparticles (SPION) were selected to study the influence of primary particle size (dP = 20 nm and 80 nm) and surface functionalization (plain, -COOH and -NH2 groups) on particle mobility. In particular, the influence of natural organic matter (NOM) on the transport and retention behaviour of SPION was investigated. In our approach, a combination of conventional breakthrough curve (BTC) analysis and magnetic resonance imaging (MRI) to non-invasively and non-destructively visualize the SPION inside the column was applied. Particle surface properties (surface functionalization and resulting zeta potential) had a major influence while their primary particle size turned out to be less relevant. In particular, the mobility of SPION was significantly increased in the presence of NOM due to the sorption of NOM onto the particle surface resulting in a more negative zeta potential. MRI provided detailed spatially resolved information complementary to the quantitative BTC results. The approach can be transferred to other porous systems and contributes to a better understanding of particle transport in environmental porous media and porous media in technical applications.

  17. Brain iron homeostasis.

    Science.gov (United States)

    Moos, Torben

    2002-11-01

    Iron is essential for virtually all types of cells and organisms. The significance of the iron for brain function is reflected by the presence of receptors for transferrin on brain capillary endothelial cells. The transport of iron into the brain from the circulation is regulated so that the extraction of iron by brain capillary endothelial cells is low in iron-replete conditions and the reverse when the iron need of the brain is high as in conditions with iron deficiency and during development of the brain. Whereas there is good agreement that iron is taken up by means of receptor-mediated uptake of iron-transferrin at the brain barriers, there are contradictory views on how iron is transported further on from the brain barriers and into the brain extracellular space. The prevailing hypothesis for transport of iron across the BBB suggests a mechanism that involves detachment of iron from transferrin within barrier cells followed by recycling of apo-transferrin to blood plasma and release of iron as non-transferrin-bound iron into the brain interstitium from where the iron is taken up by neurons and glial cells. Another hypothesis claims that iron-transferrin is transported into the brain by means of transcytosis through the BBB. This thesis deals with the topic "brain iron homeostasis" defined as the attempts to maintain constant concentrations of iron in the brain internal environment via regulation of iron transport through brain barriers, cellular iron uptake by neurons and glia, and export of iron from brain to blood. The first part deals with transport of iron-transferrin complexes from blood to brain either by transport across the brain barriers or by uptake and retrograde axonal transport in motor neurons projecting beyond the blood-brain barrier. The transport of iron and transport into the brain was examined using radiolabeled iron-transferrin. Intravenous injection of [59Fe-125]transferrin led to an almost two-fold higher accumulation of 59Fe than of

  18. Route and Regulation of Zinc, Cadmium, and Iron Transport in Rice Plants (Oryza sativa L. during Vegetative Growth and Grain Filling: Metal Transporters, Metal Speciation, Grain Cd Reduction and Zn and Fe Biofortification

    Directory of Open Access Journals (Sweden)

    Tadakatsu Yoneyama

    2015-08-01

    Full Text Available Zinc (Zn and iron (Fe are essential but are sometimes deficient in humans, while cadmium (Cd is toxic if it accumulates in the liver and kidneys at high levels. All three are contained in the grains of rice, a staple cereal. Zn and Fe concentrations in rice grains harvested under different levels of soil/hydroponic metals are known to change only within a small range, while Cd concentrations show greater changes. To clarify the mechanisms underlying such different metal contents, we synthesized information on the routes of metal transport and accumulation in rice plants by examining metal speciation, metal transporters, and the xylem-to-phloem transport system. At grain-filling, Zn and Cd ascending in xylem sap are transferred to the phloem by the xylem-to-phloem transport system operating at stem nodes. Grain Fe is largely derived from the leaves by remobilization. Zn and Fe concentrations in phloem-sap and grains are regulated within a small range, while Cd concentrations vary depending on xylem supply. Transgenic techniques to increase concentrations of the metal chelators (nicotianamine, 2′-deoxymugineic acid are useful in increasing grain Zn and Fe concentrations. The elimination of OsNRAMP5 Cd-uptake transporter and the enhancement of root cell vacuolar Cd sequestration reduce uptake and root-to-shoot transport, respectively, resulting in a reduction of grain Cd accumulation.

  19. Route and Regulation of Zinc, Cadmium, and Iron Transport in Rice Plants (Oryza sativa L.) during Vegetative Growth and Grain Filling: Metal Transporters, Metal Speciation, Grain Cd Reduction and Zn and Fe Biofortification.

    Science.gov (United States)

    Yoneyama, Tadakatsu; Ishikawa, Satoru; Fujimaki, Shu

    2015-08-13

    Zinc (Zn) and iron (Fe) are essential but are sometimes deficient in humans, while cadmium (Cd) is toxic if it accumulates in the liver and kidneys at high levels. All three are contained in the grains of rice, a staple cereal. Zn and Fe concentrations in rice grains harvested under different levels of soil/hydroponic metals are known to change only within a small range, while Cd concentrations show greater changes. To clarify the mechanisms underlying such different metal contents, we synthesized information on the routes of metal transport and accumulation in rice plants by examining metal speciation, metal transporters, and the xylem-to-phloem transport system. At grain-filling, Zn and Cd ascending in xylem sap are transferred to the phloem by the xylem-to-phloem transport system operating at stem nodes. Grain Fe is largely derived from the leaves by remobilization. Zn and Fe concentrations in phloem-sap and grains are regulated within a small range, while Cd concentrations vary depending on xylem supply. Transgenic techniques to increase concentrations of the metal chelators (nicotianamine, 2'-deoxymugineic acid) are useful in increasing grain Zn and Fe concentrations. The elimination of OsNRAMP5 Cd-uptake transporter and the enhancement of root cell vacuolar Cd sequestration reduce uptake and root-to-shoot transport, respectively, resulting in a reduction of grain Cd accumulation.

  20. Transport of iron particles generated during milling operations in multilateral wells; Transporte de particulas de aco geradas pela abertura de janelas em pocos multilaterais

    Energy Technology Data Exchange (ETDEWEB)

    Martins, Andre Leibsohn; Rezende, Carla Leonor Teixeira; Leal, Rafael Amorim Ferreira; Lourenco, Fabio Gustavo Fernandes [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil). Centro de Pesquisas]. E-mail: aleibsohn@cenpes.petrobras.com.br; rezenc@hotmail.com; ramorim@cenpes.petrobras.com.br; fabiolou@urbi.com.br

    2000-07-01

    This paper presents a series of numerical simulations aimng the definition of requirements (flow rate and fluid properties) to remove iron particles both in the inclined sections and in the riser annulus. Additionally, experimental work was developed in a pilot scale flow loop in order tocompare the behavior of water and sinthetic oil baed fluids in milling operations. (author)

  1. Cryptic splicing events in the iron transporter ABCB7 and other key target genes in SF3B1-mutant myelodysplastic syndromes.

    Science.gov (United States)

    Dolatshad, H; Pellagatti, A; Liberante, F G; Llorian, M; Repapi, E; Steeples, V; Roy, S; Scifo, L; Armstrong, R N; Shaw, J; Yip, B H; Killick, S; Kušec, R; Taylor, S; Mills, K I; Savage, K I; Smith, C W J; Boultwood, J

    2016-12-01

    The splicing factor SF3B1 is the most frequently mutated gene in myelodysplastic syndromes (MDS), and is strongly associated with the presence of ring sideroblasts (RS). We have performed a systematic analysis of cryptic splicing abnormalities from RNA sequencing data on hematopoietic stem cells (HSCs) of SF3B1-mutant MDS cases with RS. Aberrant splicing events in many downstream target genes were identified and cryptic 3' splice site usage was a frequent event in SF3B1-mutant MDS. The iron transporter ABCB7 is a well-recognized candidate gene showing marked downregulation in MDS with RS. Our analysis unveiled aberrant ABCB7 splicing, due to usage of an alternative 3' splice site in MDS patient samples, giving rise to a premature termination codon in the ABCB7 mRNA. Treatment of cultured SF3B1-mutant MDS erythroblasts and a CRISPR/Cas9-generated SF3B1-mutant cell line with the nonsense-mediated decay (NMD) inhibitor cycloheximide showed that the aberrantly spliced ABCB7 transcript is targeted by NMD. We describe cryptic splicing events in the HSCs of SF3B1-mutant MDS, and our data support a model in which NMD-induced downregulation of the iron exporter ABCB7 mRNA transcript resulting from aberrant splicing caused by mutant SF3B1 underlies the increased mitochondrial iron accumulation found in MDS patients with RS.

  2. Altered biodistribution of gallium-67 in a patient with multiple factors influencing iron-transport protein saturation

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Jeon Young; Kim, Sang Eun; Lee, Kyung Han; Kim, Byung Tae [College of Medicine, Samsung Medical Center, Seoul (Korea, Republic of)

    1998-01-01

    We present a case of a young female patient with fulminant hepatitis who showed an altered biodistribution of Ga-67, after being scanned twice at 10 month intervals. On initial scan, uptake of Ga-67 was increased in the liver, kidneys, and skeletons. Increased hepatic Ga-67 uptake may be explained by increased transferrin unbound Ga-67 that was taken up by the inflamed liver. The saturation of iron-binding proteins due to multiple transfusions may lead to increased renal and skeletal Ga-67 uptake. On follow-up scan hepatic Ga-67 uptake was markedly increased. Also increased Ga-67 uptake in the axial skeleton and normalized renal uptake were shown. The findings were consistent with iron deficiency anemia. This case demonstrates altered Ga-67 biodistribution associated with multiple transfusions, fulminant hepatitis, and iron deficiency anemia.

  3. Aquifer Thermal Energy Storage as an ecosystem service for Brussels, Belgium: investigating iron (hydr)oxide precipitation with reactive transport modeling

    Science.gov (United States)

    Anibas, Christian; Possemiers, Mathias; Huysmans, Marijke

    2016-04-01

    In an evolving energy system it is important that urbanized areas contribute to their own energy demands. To reduce greenhouse gas emissions sustainable energy systems with a high efficiency are required, e.g. using urban aquifers as an ecosystem service. Here the potential of seasonal aquifer thermal energy storage and recovery (ATES) for the Brussels-Capital Region, Belgium is investigated. An important shallow geologic formation in the Brussels Capital Region is the Brussels Sand formation, a 20-60 m thick phreatic aquifer. The Brussels Sand Formation is known for its potential for ATES systems, but also for its varying redox and hydraulic conditions. Important limiting factors for ATES systems in the Brussels Sand Formation therefore are the hydraulic conductivity and the geochemical composition of the groundwater. Near the redox boundary iron hydroxide precipitation can negatively influence ATES well performance due to clogging. The interactions between physical processes (e.g. particle transport and clogging in the wider proximity of the ATES well) and chemical processes (e.g. influence of the operation temperatures on precipitation processes) during ATES operation are complex but not well understood. Therefore we constructed numerical groundwater flow models in MODFLOW to estimate maximum pumping and injection rates of different hydraulic conditions and competing water uses in the Brussels Sand Formation. In further steps the thermal potential for ATES was quantified using MT3DMS and the reactive transport model PHT3D was applied to assess the effects of operating ATES systems near the redox boundary. Results show that initial mixing plays an important role in the development of iron(hydr)oxide precipitation around the ATES wells, with the highest concentrations around the cold wells. This behavior is enhanced by the temperature effect; temperature differences of ΔT≈10°C already influence the iron (hydr)oxide concentration. The initial injection into the

  4. Iron and the endurance athlete.

    Science.gov (United States)

    Hinton, Pamela S

    2014-09-01

    Iron is a trace mineral that is highly significant to endurance athletes. Iron is critical to optimal athletic performance because of its role in energy metabolism, oxygen transport, and acid-base balance. Endurance athletes are at increased risk for suboptimal iron status, with potential negative consequences on performance, because of the combination of increased iron needs and inadequate dietary intake. This review paper summarizes the role of iron in maximal and submaximal exercise and describes the effects of iron deficiency on exercise performance. Mechanisms that explain the increased risk of iron deficiency in endurance athletes, including exercise-associated inflammation and hepcidin release on iron sequestration, are described. Information on screening athletes for iron deficiency is presented, and suggestions to increase iron intake through diet modification or supplemental iron are provided.

  5. MgAtr7, a new type of ABC transporter from Mycosphaerella graminicola involved in iron homeostasis

    NARCIS (Netherlands)

    Zwiers, L.H.; Roohparvar, R.; Waard, de M.A.

    2007-01-01

    The ABC transporter-encoding gene MgAtr7 from the wheat pathogen Mycosphaerella graminicola was cloned based upon its high homology to ABC transporters involved in azole-fungicide sensitivity. Genomic and cDNA sequences indicated that the N-terminus of this ABC transporter contains a motif character

  6. Limiting Factors in Photosynthesis: IV. Iron Stress-Mediated Changes in Light-Harvesting and Electron Transport Capacity and its Effects on Photosynthesis in Vivo.

    Science.gov (United States)

    Terry, N

    1983-04-01

    Using iron stress to reduce the total amount of light-harvesting and electron transport components per unit leaf area, the influence of light-harvesting and electron transport capacity on photosynthesis in sugar beet (Beta vulgaris L. cv F58-554H1) leaves was explored by monitoring net CO(2) exchange rate (P) in relation to changes in the content of Chl.In most light/CO(2) environments, and especially those with high light (>/=1000 microeinsteins photosynthetically active radiation per square meter per second) and high CO(2) (>/=300 microliters CO(2) per liter air), P per area was positively correlated with changes in Chl (a + b) content (used here as an index of the total amount of light-harvesting and electron transport components). This positive correlation of P per area with Chl per area was obtained not only with Fe-deficient plants, but also over the normal range of variation in Chl contents found in healthy, Fe-sufficient plants. For example, light-saturated P per area at an ambient CO(2) concentration close to normal atmospheric levels (300 microliters CO(2) per liter air) increased by 36% with increase in Chl over the normal range, i.e. from 40 to 65 micrograms Chl per square centimeter. Iron deficiency-mediated changes in Chl content did not affect dark respiration rate or the CO(2) compensation point. The results suggest that P per area of sugar beet may be colimited by light-harvesting and electron transport capacity (per leaf area) even when CO(2) is limiting photosynthesis as occurs under field conditions.

  7. Ocean iron cycle

    Science.gov (United States)

    Boyd, Philip W.

    Interest in the biogeochemical cycle of iron has grown rapidly over the last two decades, due to the potential role of this element in modulating global climate in the geological past and ocean productivity in the present day. This trace metal has a disproportionately large effect (1 × 105 C:Fe) on photosynthetic carbon fixation by phytoplankton. In around one third of the open ocean, so-called high-nitrate low-chlorophyll (HNLC) regions, the resident phytoplankton have low growth rates despite an abundance of plant nutrients. This is due to the low supply of iron. Iron is present in the ocean in three phases, dissolved, colloidal, and particulate (biogenic and lithogenic). However, iron chemistry is complex with interactions between chemistry and biology such as the production of iron-binding siderophores by oceanic bacteria. This results in the interplay of inorganic chemistry, photochemistry, and organic complexation. Sources of new iron include dust deposition, upwelling of iron-rich deep waters, and the resuspension and lateral transport of sediments. Sinks for iron are mainly biological as evidenced by the vertical nutrient-like profile for dissolved iron in the ocean. Iron is rapidly recycled by the upper ocean biota within a so-called "ferrous wheel." The fe ratio [(new iron)/(new + regenerated iron)] provides an index of the relative supply of iron to the biota by new versus recycled iron. Over the last 15 years, interest in the potential role of iron in shaping climate in the geological past resulted in some of the most ambitious experiments in oceanography: large-scale (i.e., 50-1000 km2) iron enrichment of HNLC waters. They have provided valuable insights into how iron supply influences the biogeochemical cycles of elements such as carbon, sulfur, silicon, nitrogen, and phosphate.

  8. A field investigation on transport of carbon-supported nanoscale zero-valent iron (nZVI) in groundwater.

    Science.gov (United States)

    Busch, J; Meißner, T; Potthoff, A; Bleyl, S; Georgi, A; Mackenzie, K; Trabitzsch, R; Werban, U; Oswald, S E

    2015-10-01

    The application of nanoscale zero-valent iron (nZVI) for subsurface remediation of groundwater contaminants is a promising new technology, which can be understood as alternative to the permeable reactive barrier technique using granular iron. Dechlorination of organic contaminants by zero-valent iron seems promising. Currently, one limitation to widespread deployment is the fast agglomeration and sedimentation of nZVI in colloidal suspensions, even more so when in soils and sediments, which limits the applicability for the treatment of sources and plumes of contamination. Colloid-supported nZVI shows promising characteristics to overcome these limitations. Mobility of Carbo-Iron Colloids (CIC) - a newly developed composite material based on finely ground activated carbon as a carrier for nZVI - was tested in a field application: In this study, a horizontal dipole flow field was established between two wells separated by 5.3m in a confined, natural aquifer. The injection/extraction rate was 500L/h. Approximately 1.2kg of CIC was suspended with the polyanionic stabilizer carboxymethyl cellulose. The suspension was introduced into the aquifer at the injection well. Breakthrough of CIC was observed visually and based on total particle and iron concentrations detected in samples from the extraction well. Filtration of water samples revealed a particle breakthrough of about 12% of the amount introduced. This demonstrates high mobility of CIC particles and we suggest that nZVI carried on CIC can be used for contaminant plume remediation by in-situ formation of reactive barriers. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Plastid proteomics for elucidating iron limited remodeling of plastid physiology in diatoms

    Science.gov (United States)

    Gomes, K. M.; Nunn, B. L.; Jenkins, B. D.

    2016-02-01

    Diatoms are important primary producers in the world's oceans and their growth is constrained in large regions by low iron availability. This low iron-induced limitation of primary production is due to the requirement for iron in components of essential metabolic pathways including key chloroplast functions such as photosynthesis and nitrate assimilation. Diatoms can bloom and accumulate high biomass during introduction of iron into low iron waters, indicating adaptations allowing for their survival in iron-limited waters and rapid growth when iron becomes more abundant. Prior studies have shown that under iron limited stress, diatoms alter plastid-specific processes including components of electron transport, size of light harvesting capacity and chlorophyll content, suggesting plastid-specific protein regulation. Due to their complex evolutionary history, resulting from a secondary endosymbiosis, knowledge regarding the complement of plastid localized proteins remains limited in comparison to other model photosynthetic organisms. While in-silico prediction of diatom protein localization provides putative candidates for plastid-localization, these analyses can be limited as most plastid prediction models were developed using plants, primary endosymbionts. In order to characterize proteins enriched in diatom chloroplast and to understand how the plastid proteome is remodeled in response to iron limitation, we used mass spectrometry based proteomics to compare plastid- enriched protein fractions from Thalassiosira pseudonana, grown in iron replete and limited conditions. These analyses show that iron stress alters regulation of major metabolic pathways in the plastid including the Calvin cycle and fatty acid synthesis. These components provide promising targets to further characterize the plastid specific response to iron limitation.

  10. Transport of sucrose-modified nanoscale zero-valent iron in saturated porous media: role of media size, injection rate and input concentration.

    Science.gov (United States)

    Li, Hui; Zhao, Yong-sheng; Han, Zhan-tao; Hong, Mei

    2015-01-01

    The growing use of nanoscale zero-valent iron (NZVI) in the remediation of contaminated groundwater raises concerns regarding its transport in aquifers. Laboratory-scale sand-packed column experiments were conducted with bare and sucrose-modified NZVI (SM-NZVI) to improve our understanding of the transport of the nanoparticles in saturated porous media, as well as the role of media size, suspension injection rate and concentration on the nanoparticle behavior. As the main indicative parameters, the normalized effluent concentration was measured and the deposition rate coefficient (k) was calculated for different simulated conditions. Overall, compared to the high retention of bare NZVI in the saturated silica column, SM-NZVI suspension could travel through the coarse sand column easily. However, the transport of SM-NZVI particles was not very satisfactory in a smaller size granular matrix especially in fine silica sand. Furthermore, the value of k regularly decreased with the increasing injection rate of suspension but increased with suspension concentration, which could reflect the role of these factors in the SM-NZVI travel process. The calculation of k-value at the tests condition adequately described the experimental results from the point of deposition dynamics, which meant the assumption of first-order deposition kinetics for the transport of NZVI particles was reasonable and feasible.

  11. Cloning and Characterization of the fecC Gene Necessary for Optimal Growth under Iron-Deficiency Conditions in the Cyanobacterium Anabaena sp.PCC 7120

    Institute of Scientific and Technical Information of China (English)

    XU Wen-liang; LIU Yong-ding; ZHANG Cheng-cai; LI Juan

    2004-01-01

    The fecC gene encoding a putative iron (Ⅲ) dicitrate transporter was cloned from nitrogen-fixing cyanobacterium Anabaena sp. PCC 7120, and inactivated. The mutant grows normally in medium with NO-3, NH+4 or without combined nitrogen. But in iron-deficient medium, the mutant grows slowly. Photosynthetic properties were compared between the mutant and the wild-type strain, the content of photosynthetic pigments in the mutant is lower than that of the wild-type. The results of RT-PCR experiments show that the fecC gene is expressed under iron-deficient conditions, but is not expressed under iron-replete conditions. These results revealed that fecC gene product is required for optimal growth under iron-deficient conditions in Anabaena sp. PCC 7120.

  12. [Iron function and carcinogenesis].

    Science.gov (United States)

    Akatsuka, Shinya; Toyokuni, Shinya

    2016-07-01

    Though iron is an essential micronutrient for humans, the excess state is acknowledged to be associated with oncogenesis. For example, iron overload in the liver of the patients with hereditary hemocromatosis highly increases the risk of hepatocellular carcinoma. Also, as to asbestos-related mesothelioma, such kinds of asbestos with a higher iron content are considered to be more carcinogenic. Iron is a useful element, which enables fundamental functions for life such as oxygen carrying and electron transport. However, in the situation where organisms are unable to have good control of it, iron turns into a dangerous element which catalyzes generation of reactive oxygen. In this review, I first outline the relationships between iron and cancer in general, then give an explanation about iron-related animal carcinogenesis models.

  13. Iron deficiency in childhood

    NARCIS (Netherlands)

    Uijterschout, L.

    2015-01-01

    Iron deficiency (ID) is the most common micronutrient deficiency in the world. Iron is involved in oxygen transport, energy metabolism, immune response, and plays an important role in brain development. In infancy, ID is associated with adverse effects on cognitive, motor, and behavioral development

  14. Iron deficiency in childhood

    NARCIS (Netherlands)

    Uijterschout, L.

    2015-01-01

    Iron deficiency (ID) is the most common micronutrient deficiency in the world. Iron is involved in oxygen transport, energy metabolism, immune response, and plays an important role in brain development. In infancy, ID is associated with adverse effects on cognitive, motor, and behavioral development

  15. Alteration of the Copper-Binding Capacity of Iron-Rich Humic Colloids during Transport from Peatland to Marine Waters.

    Science.gov (United States)

    Muller, François L L; Cuscov, Marco

    2017-02-28

    Blanket bogs contain vast amounts of Sphagnum-derived organic substances which can act as powerful chelators for dissolved iron and thus enhance its export to the coastal ocean. To investigate the variations in quantity and quality of these exports, adsorptive cathodic stripping voltammetry (CSV) was used to characterize the metal binding properties of molecular weight-fractionated dissolved organic matter (MW-fractionated DOM) in the catchment and coastal plume of a small peat-draining river over a seasonal cycle. Within the plume, both iron- and copper-binding organic ligands showed a linear, conservative distribution with increasing salinity, illustrating the high stability of peatland-derived humic substances (HS). Within the catchment, humic colloids lost up to 50% of their copper-binding capacity, expressed as a molar ratio to organic carbon, after residing for 1 week or more in the main reservoir of the catchment. Immediately downstream of the reservoir, the molar ratio [L2]/[Corg], where L2 was the second strongest copper-binding ligand, was 0.75 × 10(-4) when the reservoir residence time was 5 h but 0.34 × 10(-4) when it was 25 days. Residence time did not affect the carbon specific iron-binding capacity of the humic substances which was [L]/[Corg] = (0.80 ± 0.20) × 10(-2). Our results suggest that the loss of copper-binding capacity with increasing residence time is caused by intracolloidal interactions between iron and HS during transit from peat soil to river mouth.

  16. 49 CFR 192.277 - Ductile iron pipe.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Ductile iron pipe. 192.277 Section 192.277 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY... Ductile iron pipe. (a) Ductile iron pipe may not be joined by threaded joints. (b) Ductile iron pipe may...

  17. Curcumin may impair iron status when fed to mice for six months

    Directory of Open Access Journals (Sweden)

    Dawn Chin

    2014-01-01

    Full Text Available Curcumin has been shown to have many potentially health beneficial properties in vitro and in animal models with clinical studies on the toxicity of curcumin reporting no major side effects. However, curcumin may chelate dietary trace elements and could thus potentially exert adverse effects. Here, we investigated the effects of a 6 month dietary supplementation with 0.2% curcumin on iron, zinc, and copper status in C57BL/6J mice. Compared to non-supplemented control mice, we observed a significant reduction in iron, but not zinc and copper stores, in the liver and the spleen, as well as strongly suppressed liver hepcidin and ferritin expression in the curcumin-supplemented mice. The expression of the iron-importing transport proteins divalent metal transporter 1 and transferrin receptor 1 was induced, while hepatic and splenic inflammatory markers were not affected in the curcumin-fed mice. The mRNA expression of other putative target genes of curcumin, including the nuclear factor (erythroid-derived 2-like 2 and haem oxygenase 1 did not differ between the groups. Most of the published animal trials with curcumin-feeding have not reported adverse effects on iron status or the spleen. However, it is possible that long-term curcumin supplementation and a Western-type diet may aggravate iron deficiency. Therefore, our findings show that further studies are needed to evaluate the effect of curcumin supplementation on iron status.

  18. TonB-dependent heme iron acquisition in the tsetse fly symbiont Sodalis glossinidius.

    Science.gov (United States)

    Hrusa, Gili; Farmer, William; Weiss, Brian L; Applebaum, Taylor; Roma, Jose Santinni; Szeto, Lauren; Aksoy, Serap; Runyen-Janecky, Laura J

    2015-04-01

    Sodalis glossinidius is an intra- and extracellular symbiont of the tsetse fly (Glossina sp.), which feeds exclusively on vertebrate blood. S. glossinidius resides in a wide variety of tsetse tissues and may encounter environments that differ dramatically in iron content. The Sodalis chromosome encodes a putative TonB-dependent outer membrane heme transporter (HemR) and a putative periplasmic/inner membrane ABC heme permease system (HemTUV). Because these gene products mediate iron acquisition processes by other enteric bacteria, we characterized their regulation and physiological role in the Sodalis/tsetse system. Our results show that the hemR and tonB genes are expressed by S. glossinidius in the tsetse fly. Furthermore, transcription of hemR in Sodalis is repressed in a high-iron environment by the iron-responsive transcriptional regulator Fur. Expression of the S. glossinidius hemR and hemTUV genes in an Escherichia coli strain unable to use heme as an iron source stimulated growth in the presence of heme or hemoglobin as the sole iron source. This stimulation was dependent on the presence of either the E. coli or Sodalis tonB gene. Sodalis tonB and hemR mutant strains were defective in their ability to colonize the gut of tsetse flies that lacked endogenous symbionts, while wild-type S. glossinidius proliferated in this same environment. Finally, we show that the Sodalis HemR protein is localized to the bacterial membrane and appears to bind hemin. Collectively, this study provides strong evidence that TonB-dependent, HemR-mediated iron acquisition is important for the maintenance of symbiont homeostasis in the tsetse fly, and it provides evidence for the expression of bacterial high-affinity iron acquisition genes in insect symbionts. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  19. Evaluating the mobility of polymer-stabilised zero-valent iron nanoparticles and their potential to co-transport contaminants in intact soil cores.

    Science.gov (United States)

    Chekli, L; Brunetti, G; Marzouk, E R; Maoz-Shen, A; Smith, E; Naidu, R; Shon, H K; Lombi, E; Donner, E

    2016-09-01

    The use of zero-valent iron nanoparticles (nZVI) has been advocated for the remediation of both soils and groundwater. A key parameter affecting nZVI remediation efficacy is the mobility of the particles as this influences the reaction zone where remediation can occur. However, by engineering nZVI particles with increased stability and mobility we may also inadvertently facilitate nZVI-mediated contaminant transport away from the zone of treatment. Previous nZVI mobility studies have often been limited to model systems as the presence of background Fe makes detection and tracking of nZVI in real systems difficult. We overcame this problem by synthesising Fe-59 radiolabelled nZVI. This enabled us to detect and quantify the leaching of nZVI-derived Fe-59 in intact soil cores, including a soil contaminated by Chromated-Copper-Arsenate. Mobility of a commercially available nZVI was also tested. The results showed limited mobility of both nanomaterials; mobility of nZVI below the injection/remediation zone was very limited. This Fe-59 experimental approach can be further extended to test nZVI transport in a wider range of contaminated soil types and textures and using different application methods and rates. The resulting database could then be used to develop and validate modelling of nZVI-facilitated contaminant transport on an individual soil basis suitable for site specific risk assessment prior to nZVI remediation.

  20. Iron acquisition functions expressed by the human pathogen Acinetobacter baumannii.

    Science.gov (United States)

    Zimbler, Daniel L; Penwell, William F; Gaddy, Jennifer A; Menke, Sharon M; Tomaras, Andrew P; Connerly, Pamela L; Actis, Luis A

    2009-02-01

    Acinetobacter baumannii is a gram-negative bacterium that causes serious infections in compromised patients. More recently, it has emerged as the causative agent of severe infections in military personnel wounded in Iraq and Afghanistan. This pathogen grows under a wide range of conditions including iron-limiting conditions imposed by natural and synthetic iron chelators. Initial studies using the type strain 19606 showed that the iron proficiency of this pathogen depends on the expression of the acinetobactin-mediated iron acquisition system. More recently, we have observed that hemin but not human hemoglobin serves as an iron source when 19606 isogenic derivatives affected in acinetobactin transport and biosynthesis were cultured under iron-limiting conditions. This finding is in agreement with the observation that the genome of the strain 17978 has a gene cluster coding for putative hemin-acquisition functions, which include genes coding for putative hemin utilization functions and a TonBExbBD energy transducing system. This system restored enterobactin biosynthesis in an E. coli ExbBD deficient strain but not when introduced into a TonB mutant. PCR and Southern blot analyses showed that this hemin-utilization gene cluster is also present in the 19606 strain. Analysis of the 17978 genome also showed that this strain harbors genes required for acinetobactin synthesis and transport as well as a gene cluster that could code for additional iron acquisition functions. This hypothesis is in agreement with the fact that the inactivation of the basD acinetobactin biosynthetic gene did not affect the growth of A. baumannii 17978 cells under iron-chelated conditions. Interestingly, this second iron uptake gene cluster is flanked by perfect inverted repeats and includes transposase genes that are expressed transcriptionally. Also interesting is the observation that this additional cluster could not be detected in the type strain 19606, an observation that suggests some

  1. Catechol Siderophore Transport by Vibrio cholerae.

    Science.gov (United States)

    Wyckoff, Elizabeth E; Allred, Benjamin E; Raymond, Kenneth N; Payne, Shelley M

    2015-09-01

    Siderophores, small iron-binding molecules secreted by many microbial species, capture environmental iron for transport back into the cell. Vibrio cholerae synthesizes and uses the catechol siderophore vibriobactin and also uses siderophores secreted by other species, including enterobactin produced by Escherichia coli. E. coli secretes both canonical cyclic enterobactin and linear enterobactin derivatives likely derived from its cleavage by the enterobactin esterase Fes. We show here that V. cholerae does not use cyclic enterobactin but instead uses its linear derivatives. V. cholerae lacked both a receptor for efficient transport of cyclic enterobactin and enterobactin esterase to promote removal of iron from the ferrisiderophore complex. To further characterize the transport of catechol siderophores, we show that the linear enterobactin derivatives were transported into V. cholerae by either of the catechol siderophore receptors IrgA and VctA, which also transported the synthetic siderophore MECAM [1,3,5-N,N',N″-tris-(2,3-dihydroxybenzoyl)-triaminomethylbenzene]. Vibriobactin is transported via the additional catechol siderophore receptor ViuA, while the Vibrio fluvialis siderophore fluvibactin was transported by all three catechol receptors. ViuB, a putative V. cholerae siderophore-interacting protein (SIP), functionally substituted for the E. coli ferric reductase YqjH, which promotes the release of iron from the siderophore in the bacterial cytoplasm. In V. cholerae, ViuB was required for the use of vibriobactin but was not required for the use of MECAM, fluvibactin, ferrichrome, or the linear derivatives of enterobactin. This suggests the presence of another protein in V. cholerae capable of promoting the release of iron from these siderophores. Vibrio cholerae is a major human pathogen and also serves as a model for the Vibrionaceae, which include other serious human and fish pathogens. The ability of these species to persist and acquire essential

  2. Catechol Siderophore Transport by Vibrio cholerae

    Science.gov (United States)

    Allred, Benjamin E.; Raymond, Kenneth N.; Payne, Shelley M.

    2015-01-01

    ABSTRACT Siderophores, small iron-binding molecules secreted by many microbial species, capture environmental iron for transport back into the cell. Vibrio cholerae synthesizes and uses the catechol siderophore vibriobactin and also uses siderophores secreted by other species, including enterobactin produced by Escherichia coli. E. coli secretes both canonical cyclic enterobactin and linear enterobactin derivatives likely derived from its cleavage by the enterobactin esterase Fes. We show here that V. cholerae does not use cyclic enterobactin but instead uses its linear derivatives. V. cholerae lacked both a receptor for efficient transport of cyclic enterobactin and enterobactin esterase to promote removal of iron from the ferrisiderophore complex. To further characterize the transport of catechol siderophores, we show that the linear enterobactin derivatives were transported into V. cholerae by either of the catechol siderophore receptors IrgA and VctA, which also transported the synthetic siderophore MECAM [1,3,5-N,N′,N″-tris-(2,3-dihydroxybenzoyl)-triaminomethylbenzene]. Vibriobactin is transported via the additional catechol siderophore receptor ViuA, while the Vibrio fluvialis siderophore fluvibactin was transported by all three catechol receptors. ViuB, a putative V. cholerae siderophore-interacting protein (SIP), functionally substituted for the E. coli ferric reductase YqjH, which promotes the release of iron from the siderophore in the bacterial cytoplasm. In V. cholerae, ViuB was required for the use of vibriobactin but was not required for the use of MECAM, fluvibactin, ferrichrome, or the linear derivatives of enterobactin. This suggests the presence of another protein in V. cholerae capable of promoting the release of iron from these siderophores. IMPORTANCE Vibrio cholerae is a major human pathogen and also serves as a model for the Vibrionaceae, which include other serious human and fish pathogens. The ability of these species to persist and

  3. Global transcriptional responses of Pseudomonas syringae DC3000 to changes in iron bioavailability in vitro

    Directory of Open Access Journals (Sweden)

    Rutzke Michael

    2008-12-01

    Full Text Available Abstract Background Pseudomonas syringae pv tomato DC3000 (DC3000 is a Gram-negative model plant pathogen that is found in a wide variety of environments. To survive in these diverse conditions it must sense and respond to various environmental cues. One micronutrient required for most forms of life is iron. Bioavailable iron has been shown to be an important global regulator for many bacteria where it not only regulates a wide variety of genes involved in general cell physiology but also virulence determinants. In this study we used microarrays to study differential gene regulation in DC3000 in response to changes in levels of cell-associated iron. Results DC3000 cultures were grown under highly controlled conditions and analyzed after the addition of iron citrate or sodium citrate to the media. In the cultures supplemented with iron, we found that cell-associated iron increased rapidly while culture densities were not significantly different over 4 hours when compared to cultures with sodium citrate added. Microarray analysis of samples taken from before and after the addition of either sodium citrate or iron citrate identified 386 differentially regulated genes with high statistical confidence. Differentially regulated genes were clustered based on expression patterns observed between comparison of samples taken at different time points and with different supplements. This analysis grouped genes associated with the same regulatory motifs and/or had similar putative or known function. Conclusion This study shows iron is rapidly taken up from the medium by iron-depleted DC3000 cultures and that bioavailable iron is a global cue for the expression of iron transport, storage, and known virulence factors in DC3000. Furthermore approximately 34% of the differentially regulated genes are associated with one of four regulatory motifs for Fur, PvdS, HrpL, or RpoD.

  4. Stabilisation of nanoscale zero-valent iron with biochar for enhanced transport and in-situ remediation of hexavalent chromium in soil.

    Science.gov (United States)

    Su, Huijie; Fang, Zhanqiang; Tsang, Pokeung Eric; Fang, Jianzhang; Zhao, Dongye

    2016-07-01

    In this study, a biochar-supported nanoscale zero-valent iron (nZVI@BC) material was used for in situ remediation of hexavalent chromium-contaminated soil. Sedimentation tests and column experiments were used to compare the stability and mobility of nZVI@BC and bare-nZVI. The immobilisation efficiency of chromium, toxic effect of chromium and the content of iron were assessed through leaching tests and pot experiments. Sedimentation tests and transport experiments indicated that nZVI@BC with nZVI to BC mass ratio of 1:1 exhibited better stability and mobility than that of bare-nZVI. The immobilisation efficiency of Cr(VI) and Crtotal was 100% and 92.9%, respectively, when the soil was treated with 8 g/kg of nZVI@BC for 15 days. Moreover, such remediation effectively reduced the leachability of Fe caused by bare-nZVI. In addition, pot experiments showed that such remediation reduced the phytotoxicity of Cr and the leachable Fe and was favourable for plant growth.

  5. Monte Carlo transport model comparison with 1A GeV accelerated iron experiment: heavy-ion shielding evaluation of NASA space flight-crew foodstuff

    Science.gov (United States)

    Stephens, D. L.; Townsend, L. W.; Miller, J.; Zeitlin, C.; Heilbronn, L.

    Deep-space manned flight as a reality depends on a viable solution to the radiation problem. Both acute and chronic radiation health threats are known to exist, with solar particle events as an example of the former and galactic cosmic rays (GCR) of the latter. In this experiment Iron ions of 1A GeV are used to simulate GCR and to determine the secondary radiation field created as the GCR-like particles interact with a thick target. A NASA prepared food pantry locker was subjected to the iron beam and the secondary fluence recorded. A modified version of the Monte Carlo heavy ion transport code developed by Zeitlin at LBNL is compared with experimental fluence. The foodstuff is modeled as mixed nuts as defined by the 71 st edition of the Chemical Rubber Company (CRC) Handbook of Physics and Chemistry. The results indicate a good agreement between the experimental data and the model. The agreement between model and experiment is determined using a linear fit to ordered pairs of data. The intercept is forced to zero. The slope fit is 0.825 and the R 2 value is 0.429 over the resolved fluence region. The removal of an outlier, Z=14, gives values of 0.888 and 0.705 for slope and R 2 respectively.

  6. The fluoroquinolone levofloxacin triggers the transcriptional activation of iron transport genes that contribute to cell death in Streptococcus pneumoniae.

    Science.gov (United States)

    Ferrándiz, María-José; de la Campa, Adela G

    2014-01-01

    We studied the transcriptomic response of Streptococcus pneumoniae to levofloxacin (LVX) under conditions inhibiting topoisomerase IV but not gyrase. Although a complex transcriptomic response was observed, the most outstanding result was the upregulation of the genes of the fatDCEB operon, involved in iron (Fe(2+) and Fe(3+)) uptake, which were the only genes varying under every condition tested. Although the inhibition of topoisomerase IV by levofloxacin did not have a detectable effect in the level of global supercoiling, increases in general supercoiling and fatD transcription were observed after topoisomerase I inhibition, while the opposite was observed after gyrase inhibition with novobiocin. Since fatDCEB is located in a topological chromosomal domain downregulated by DNA relaxation, we studied the transcription of a copy of the 422-bp (including the Pfat promoter) region located upstream of fatDCEB fused to the cat reporter inserted into the chromosome 106 kb away from its native position: PfatfatD was upregulated in the presence of LVX in its native location, whereas no change was observed in the Pfatcat construction. Results suggest that topological changes are indeed involved in PfatfatDCE transcription. Upregulation of fatDCEB would lead to an increase of intracellular iron and, in turn, to the activation of the Fenton reaction and the increase of reactive oxygen species. In accordance, we observed an attenuation of levofloxacin lethality in iron-deficient media and in a strain lacking the gene coding for SpxB, the main source of hydrogen peroxide. In addition, we observed an increase of reactive oxygen species that contributed to levofloxacin lethality.

  7. Siderophore-mediated iron acquisition systems in Bacillus cereus: Identification of receptors for anthrax virulence-associated petrobactin .

    Science.gov (United States)

    Zawadzka, Anna M; Abergel, Rebecca J; Nichiporuk, Rita; Andersen, Ulla N; Raymond, Kenneth N

    2009-04-28

    During growth under iron limitation, Bacillus cereus and Bacillus anthracis, two human pathogens from the Bacillus cereus group of Gram-positive bacteria, secrete two siderophores, bacillibactin (BB) and petrobactin (PB), for iron acquisition via membrane-associated substrate-binding proteins (SBPs) and other ABC transporter components. Since PB is associated with virulence traits in B. anthracis, the PB-mediated iron uptake system presents a potential target for antimicrobial therapies; its characterization in B. cereus is described here. Separate transporters for BB, PB, and several xenosiderophores are suggested by (55)Fe-siderophore uptake studies. The PB precursor, 3,4-dihydroxybenzoic acid (3,4-DHB), and the photoproduct of FePB (FePB(nu)) also mediate iron delivery into iron-deprived cells. Putative SBPs were recombinantly expressed, and their ligand specificity and binding affinity were assessed using fluorescence spectroscopy. The noncovalent complexes of the SBPs with their respective siderophores were characterized using ESI-MS. The differences between solution phase behavior and gas phase measurements are indicative of noncovalent interactions between the siderophores and the binding sites of their respective SBPs. These studies combined with bioinformatics sequence comparison identify SBPs from five putative transporters specific for BB and enterobactin (FeuA), 3,4-DHB and PB (FatB), PB (FpuA), schizokinen (YfiY), and desferrioxamine and ferrichrome (YxeB). The two PB receptors show different substrate ranges: FatB has the highest affinity for ferric 3,4-DHB, iron-free PB, FePB, and FePB(nu), whereas FpuA is specific to only apo- and ferric PB. The biochemical characterization of these SBPs provides the first identification of the transporter candidates that most likely play a role in the B. cereus group pathogenicity.

  8. Siderophore-mediated iron acquisition systems in Bacillus cereus: identification of receptors for anthrax virulence-associated petrobactin†a

    Science.gov (United States)

    Zawadzka, Anna M.; Abergel, Rebecca J.; Nichiporuk, Rita; Andersen, Ulla N.; Raymond, Kenneth N.

    2009-01-01

    During growth under iron limitation, Bacillus cereus and Bacillus anthracis, two human pathogens from the Bacillus cereus group of Gram-positive bacteria, secrete two siderophores, bacillibactin (BB) and petrobactin (PB), for iron acquisition via membrane-associated substrate-binding proteins (SBPs) and other ABC transporter components. Since PB is associated with virulence traits in B. anthracis, the PB-mediated iron uptake system presents a potential target for antimicrobial therapies; its characterization in B. cereus is described here. Separate transporters for BB, PB, and several xenosiderophores are suggested by 55Fe-siderophore uptake studies. The PB precursor, 3,4-dihydroxybenzoic acid (3,4-DHB), and the photoproduct of FePB (FePBν) also mediate iron delivery into iron-deprived cells. Putative SBPs were recombinantly expressed, and their ligand specificity and binding affinity assessed using fluorescence spectroscopy. The noncovalent complexes of the SBPs with their respective siderophores were characterized using ESI-MS. The differences between solution phase behavior and gas phase measurements are indicative of noncovalent interactions between the siderophores and the binding sites of their respective SBPs. These studies combined with bioinformatics sequence comparison identify SBPs from five putative transporters specific for BB and enterobactin (FeuA), 3,4-DHB and PB (FatB), PB (FpuA), schizokinen (YfiY), and desferrioxamine and ferrichrome (YxeB). The two PB receptors show different substrate ranges: FatB has the highest affinity for ferric 3,4-DHB, iron-free PB, FePB, and FePBν, whereas FpuA is specific to only apo- and ferric PB. The biochemical characterization of these SBPs provides the first identification of the transporter candidates that most likely play a role in the B. cereus group pathogenicity. PMID:19254027

  9. Effect of injection velocity and particle concentration on transport of nanoscale zero-valent iron and hydraulic conductivity in saturated porous media.

    Science.gov (United States)

    Strutz, Tessa J; Hornbruch, Götz; Dahmke, Andreas; Köber, Ralf

    2016-08-01

    Successful groundwater remediation by injecting nanoscale zero-valent iron (NZVI) particles requires efficient particle transportation and distribution in the subsurface. This study focused on the influence of injection velocity and particle concentration on the spatial NZVI particle distribution, the deposition processes and on quantifying the induced decrease in hydraulic conductivity (K) as a result of particle retention by lab tests and numerical simulations. Horizontal column tests of 2m length were performed with initial Darcy injection velocities (q0) of 0.5, 1.5, and 4.1m/h and elemental iron input concentrations (Fe(0)in) of 0.6, 10, and 17g/L. Concentrations of Fe(0) in the sand were determined by magnetic susceptibility scans, which provide detailed Fe(0) distribution profiles along the column. NZVI particles were transported farther at higher injection velocity and higher input concentrations. K decreased by one order of magnitude during injection in all experiments, with a stronger decrease after reaching Fe(0) concentrations of about 14-18g/kg(sand). To simulate the observed nanoparticle transport behavior the existing finite-element code OGS has been successfully extended and parameterized for the investigated experiments using blocking, ripening, and straining as governing deposition processes. Considering parameter relationships deduced from single simulations for each experiment (e.g. deposition rate constants as a function of flow velocity) one mean parameter set has been generated reproducing the observations in an adequate way for most cases of the investigated realistic injection conditions. An assessment of the deposition processes related to clogging effects showed that the percentage of retention due to straining and ripening increased during experimental run time resulting in an ongoing reduction of K. Clogging is mainly evoked by straining which dominates particle deposition at higher flow velocities, while blocking and ripening play a

  10. Differential Regulation of Ferritin Subunits and Iron Transport Proteins: An Effect of Targeted Hepatic X-Irradiation

    Directory of Open Access Journals (Sweden)

    Naila Naz

    2013-01-01

    Full Text Available The current study aimed to investigate radiation-induced regulation of iron proteins including ferritin subunits in rats. Rat livers were selectively irradiated in vivo at 25 Gy. This dose can be used to model radiation effects to the liver without inducing overt radiation-induced liver disease. Sham-irradiated rats served as controls. Isolated hepatocytes were irradiated at 8 Gy. Ferritin light polypeptide (FTL was detectable in the serum of sham-irradiated rats with an increase after irradiation. Liver irradiation increased hepatic protein expression of both ferritin subunits. A rather early increase (3 h was observed for hepatic TfR1 and Fpn-1 followed by a decrease at 12 h. The increase in TfR2 persisted over the observed time. Parallel to the elevation of AST levels, a significant increase (24 h in hepatic iron content was measured. Complete blood count analysis showed a significant decrease in leukocyte number with an early increase in neutrophil granulocytes and a decrease in lymphocytes. In vitro, a significant increase in ferritin subunits at mRNA level was detected after irradiation which was further induced with a combination treatment of irradiation and acute phase cytokine. Irradiation can directly alter the expression of ferritin subunits and this response can be strongly influenced by radiation-induced proinflammatory cytokines. FTL can be used as a serum marker for early phase radiation-induced liver damage.

  11. Importance of Ekman transport and gyre circulation change on seasonal variation of surface dissolved iron in the western subarctic North Pacific

    Science.gov (United States)

    Nakanowatari, Takuya; Nakamura, Tomohiro; Uchimoto, Keisuke; Nishioka, Jun; Mitsudera, Humio; Wakatsuchi, Masaaki

    2017-05-01

    Iron (Fe) is an essential nutrient for marine phytoplankton and it constitutes an important element in the marine carbon cycle in the ocean. This study examined the mechanisms controlling seasonal variation of dissolved Fe (dFe) in the western subarctic North Pacific (WSNP), using an ocean general circulation model coupled with a simple biogeochemical model incorporating a dFe cycle fed by two major sources (atmospheric dust and continental shelf sediment). The model reproduced the seasonal cycle of observed concentrations of dFe and macronutrients at the surface in the Oyashio region with maxima in winter (February-March) and minima in summer (July-September), although the simulated seasonal amplitudes are a half of the observed values. Analysis of the mixed-layer dFe budget indicated that both local vertical entrainment and lateral advection are primary contributors to the wintertime increase in dFe concentration. In early winter, strengthened northwesterly winds excite southward Ekman transport and Ekman upwelling over the western subarctic gyre, transporting dFe-rich water southward. In mid to late winter, the southward western boundary current of the subarctic gyre and the outflow from the Sea of Okhotsk also bring dFe-rich water to the Oyashio region. The contribution of atmospheric dust to the dFe budget is several times smaller than these ocean transport processes in winter. These results suggest that the westerly wind-induced Ekman transport and gyre circulation systematically influence the seasonal cycle of WSNP surface dFe concentration.

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

    Science.gov (United States)

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

    2015-01-01

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

  13. The role of transition metal transporters for iron, zinc, manganese, and copper in the pathogenesis of Yersinia pestis.

    Science.gov (United States)

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

    2015-06-01

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

  14. Further Analysis of the Function of AtBHLH29 in Regulating the Iron Uptake Process in Arabidopsis thaliana

    Institute of Scientific and Technical Information of China (English)

    Juan Zhang; Hui-Fen Zhu; Hui Liang; Kun-Fan Liu; Ai-Min Zhang; Hong-Qing Ling; Dao-Wen Wang

    2006-01-01

    Using T-DNA insertion and chemical mutants, two recent studies have shown that AtBHLH29, encoding a putative basic helix-loop-helix (BHLH) protein, is involved in regulating the iron uptake process in Arabidopsis thaliana. Herein, we report that RNA interference (RNAi) mutants can be used to reveal more accurately the genetic function of AtBHLH29. We compared the iron deficiency responses of seven RNAi strains that contained decreasing amounts of AtBHLH29transcripts. Under high iron conditions (50 μmol/L iron), only in the most severe RNAi strains (R101, R111, and R119) was plant growth significantly retarded. However, these mutants could still survive and produce seeds. This suggests that the function of AtBHLH29 is beneficial, but not absolutely essential, to plant growth when iron supply is not limiting. Under low iron conditions (less than 10 μmol/L iron), the R111 and R119 strains died prematurely, demonstrating that AtBHLH29 is absolutely necessary for plant survival when iron supply is restricted. The transcription of AtBHLH29 was essential for the expression of AtFRO2 (encoding the ferric chelate reductase). In contrast, the expression of AtlRT1(encoding the high-affinity iron transporter) was not so strongly dependent upon the transcription of AtBHLH29.By transient expression, we found that the AtBHLH29-GUS fusion protein was targeted specifically to the nucleus in plant cells. Interestingly, the nuclear localization of AtBHLH29-GUS was abolished when the four consecutive arginine residues located in the basic region of the putative AtBHLH29 protein were replaced by alanine residues by mutagenesis. The implications of our findings on further studies of the mechanism underlying the function of AtBHLH29 are discussed.

  15. Spin transport in as-grown and annealed thulium iron garnet/platinum bilayers with perpendicular magnetic anisotropy

    Science.gov (United States)

    Avci, Can Onur; Quindeau, Andy; Mann, Maxwell; Pai, Chi-Feng; Ross, Caroline A.; Beach, Geoffrey S. D.

    2017-03-01

    We characterize the spin Hall magnetoresistance (SMR), spin Seebeck effect (SSE), and dampinglike spin-orbit torque (SOT) in thulium iron garnet/platinum bilayers with perpendicular magnetic anisotropy by using harmonic Hall effect measurements. By consecutive annealing steps followed by measurements on a single device, we reveal that the spin-dependent effects gradually decrease in amplitude as the annealing temperature increases. We attribute this behavior primarily to the changes in the spin-mixing conductance, which sensitively depends on the interface quality. However, further analysis demonstrates that although the SSE scales closely with the SMR, the dampinglike SOT shows a significantly different trend upon annealing, contrary to theoretical expectations. By comparing the dampinglike SOT with the field-induced Hall effect, we found evidence that scattering from Fe impurities in the Pt at the interface might be responsible for the distinct annealing temperature dependence of the dampinglike SOT.

  16. Dissolved iron transport pathways in the Ross Sea: Influence of tides and horizontal resolution in a regional ocean model

    Science.gov (United States)

    Mack, Stefanie L.; Dinniman, Michael S.; McGillicuddy, Dennis J.; Sedwick, Peter N.; Klinck, John M.

    2017-02-01

    Phytoplankton production in the Ross Sea is regulated by the availability of dissolved iron (dFe), a limiting micro-nutrient, whose sources include Circumpolar Deep Water, sea ice melt, glacial melt, and benthic sources (sediment efflux and remineralization). We employ a passive tracer dye to model the benthic dFe sources and track pathways from deep areas of the continental shelf to the surface mixed layer in simulations with and without tidal forcing, and at 5 and 1.5 km horizontal resolution. This, combined with dyes for each of the other dFe sources, provides an estimate of total dFe supply to surface waters. We find that tidal forcing increases the amount of benthic dye that covers the banks on the continental shelf. Calculations of mixed layer depth to define the surface ocean give similar average values over the shelf, but spatial patterns differ between simulations, particularly along the ice shelf front. Benthic dFe supply in simulations shows an increase with tidal forcing and a decrease with higher resolution. The changes in benthic dFe supply control the difference in total supply between simulations. Overall, the total dFe supply from simulations varies from 5.60 to 7.95 μmol m-2 year-1, with benthic supply comprising 32-50%, comparing well with recent data and model synthesis. We suggest that including tides and using high horizontal resolution is important, especially when considering spatial variability of iron supply on the Ross Sea shelf.

  17. 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

    Directory of Open Access Journals (Sweden)

    Gaëlle ePorcheron

    2013-12-01

    Full Text Available 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.

  18. Transport processes of the legume symbiosome membrane

    Directory of Open Access Journals (Sweden)

    Victoria C Clarke

    2014-12-01

    Full Text Available The symbiosome membrane (SM is a physical barrier between the host plant and nitrogen-fixing bacteria in the legume-rhizobium symbiosis, and represents a regulated interface for the movement of solutes between the symbionts that is under plant control. The primary nutrient exchange across the SM is the transport of a carbon energy source from plant to bacteroid in exchange for fixed nitrogen. At a biochemical level two channels have been implicated in movement of fixed nitrogen across the SM and a uniporter that transports monovalent dicarboxylate ions has been characterized that would transport fixed carbon. The aquaporin NOD26 may provide a channel for ammonia, but the genes encoding the other transporters have not been identified. Transport of several other solutes, including calcium and potassium, have been demonstrated in isolated symbiosomes, and genes encoding transport systems for the movement of iron, nitrate, sulfate and zinc in nodules have been identified. However, definitively matching transport activities with these genes has proved difficult and many further transport processes are expected on the SM to facilitate the movement of nutrients between the symbionts. Recently, work detailing the SM proteome in soybean has been completed, contributing significantly to the database of known SM proteins. This represents a valuable resource for the identification of transporter protein candidates, some of which may correspond to transport processes previously described, or to novel transport systems in the symbiosis. Putative transporters identified from the proteome include homologues of transporters of sulfate, calcium, peptides and various metal ions. Here we review current knowledge of transport processes of the SM and discuss the requirements for additional transport routes of other nutrients exchanged in the symbiosis, with a focus on transport systems identified through the soybean SM proteome.

  19. Iron deficiency and iron deficiency anemia in women.

    Science.gov (United States)

    Coad, Jane; Pedley, Kevin

    2014-01-01

    Iron deficiency is one of the most common nutritional problems in the world and disproportionately affects women and children. Stages of iron deficiency can be characterized as mild deficiency where iron stores become depleted, marginal deficiency where the production of many iron-dependent proteins is compromised but hemoglobin levels are normal and iron deficiency anemia where synthesis of hemoglobin is decreased and oxygen transport to the tissues is reduced. Iron deficiency anemia is usually assessed by measuring hemoglobin levels but this approach lacks both specificity and sensitivity. Failure to identify and treat earlier stages of iron deficiency is concerning given the neurocognitive implications of iron deficiency without anemia. Most of the daily iron requirement is derived from recycling of senescent erythrocytes by macrophages; only 5-10 % comes from the diet. Iron absorption is affected by inhibitors and enhancers of iron absorption and by the physiological state. Inflammatory conditions, including obesity, can result in iron being retained in the enterocytes and macrophages causing hypoferremia as a strategic defense mechanism to restrict iron availability to pathogens. Premenopausal women usually have low iron status because of iron loss in menstrual blood. Conditions which further increase iron loss, compromise absorption or increase demand, such as frequent blood donation, gastrointestinal lesions, athletic activity and pregnancy, can exceed the capacity of the gastrointestinal tract to upregulate iron absorption. Women of reproductive age are at particularly high risk of iron deficiency and its consequences however there is a controversial argument that evolutionary pressures have resulted in an iron deficient phenotype which protects against infection.

  20. Genome-wide analysis of copper, iron and zinc transporters in the arbuscular mycorrhizal fungus Rhizophagus irregularis

    Directory of Open Access Journals (Sweden)

    Elisabeth eTamayo

    2014-10-01

    Full Text Available Arbuscular mycorrhizal fungi (AMF, belonging to the Glomeromycota, are soil microorganisms that establish mutualistic symbioses with the majority of higher plants. The efficient uptake of low mobility mineral nutrients by the fungal symbiont and their further transfer to the plant is a major feature of this symbiosis. Besides improving plant mineral nutrition, AMF can alleviate heavy metal toxicity to their host plants and are able to tolerate high metal concentrations in the soil. Nevertheless, we are far from understanding the key molecular determinants of metal homeostasis in these organisms. To get some insights into these mechanisms, a genome-wide analysis of Cu, Fe and Zn transporters was undertaken, making use of the recently published whole genome of the AMF Rhizophagus irregularis. This in silico analysis allowed identification of 30 open reading frames in the R. irregularis genome, which potentially encode metal transporters. Phylogenetic comparisons with the genomes of a set of reference fungi showed an expansion of some metal transporter families. Analysis of the published transcriptomic profiles of R. irregularis revealed that a set of genes were up-regulated in mycorrhizal roots compared to germinated spores and extraradical mycelium, which suggests that metals are important for plant colonization.

  1. Genome-wide analysis of copper, iron and zinc transporters in the arbuscular mycorrhizal fungus Rhizophagus irregularis

    Science.gov (United States)

    Tamayo, Elisabeth; Gómez-Gallego, Tamara; Azcón-Aguilar, Concepción; Ferrol, Nuria

    2014-01-01

    Arbuscular mycorrhizal fungi (AMF), belonging to the Glomeromycota, are soil microorganisms that establish mutualistic symbioses with the majority of higher plants. The efficient uptake of low mobility mineral nutrients by the fungal symbiont and their further transfer to the plant is a major feature of this symbiosis. Besides improving plant mineral nutrition, AMF can alleviate heavy metal toxicity to their host plants and are able to tolerate high metal concentrations in the soil. Nevertheless, we are far from understanding the key molecular determinants of metal homeostasis in these organisms. To get some insights into these mechanisms, a genome-wide analysis of Cu, Fe and Zn transporters was undertaken, making use of the recently published whole genome of the AMF Rhizophagus irregularis. This in silico analysis allowed identification of 30 open reading frames in the R. irregularis genome, which potentially encode metal transporters. Phylogenetic comparisons with the genomes of a set of reference fungi showed an expansion of some metal transporter families. Analysis of the published transcriptomic profiles of R. irregularis revealed that a set of genes were up-regulated in mycorrhizal roots compared to germinated spores and extraradical mycelium, which suggests that metals are important for plant colonization. PMID:25352857

  2. Alternative expression of vacuolar iron transporter and ferritin genes leads to blue/purple coloration of flowers in tulip cv. 'Murasakizuisho'.

    Science.gov (United States)

    Shoji, Kazuaki; Momonoi, Kazumi; Tsuji, Tosiaki

    2010-02-01

    Flowers of tulip cv. 'Murasakizuisho' have a purple perianth except for the bottom region, which is blue in color even though it has the same anthocyanin, delphinidin 3-O-rutinoside, as the entire perianth. The development of the blue coloration in the perianth bottom is due to complexation by anthocyanin, flavonol and iron (Fe), as well as a vacuolar iron transporter, TgVit1. Although transient expression of TgVit1 in the purple cells led to a color change to light blue, the coloration of the transformed cells did not coincide with the dark blue color of the cells of the perianth bottom. We thought that another factor is required for the blue coloration of the cells of perianth bottom. To examine the effect of ferritin (FER), an Fe storage protein, on blue color development, we cloned an FER gene (TgFER1) and performed expression analyses. TgFER1 transcripts were found in the cells located in the upper region of the petals along with purple color development by anthocyanin and were not found in the blue cells of the perianth bottom. This gene expression is in contrast to that of TgVit1, expressed only in the cells of the perianth bottom. Co-expression of TgVIT1 and TgFER-RNAi, constructed for suppressing endogenous TgFER1 by RNA interference (RNAi), changed the purple petal cells to a dark blue color similar to that of the natural perianth bottom. These results strongly suggest that TgVit1 expression and TgFER1 suppression are critical for the development of blue color in the perianth bottom.

  3. Iron Test

    Science.gov (United States)

    ... as: Serum Iron; Serum Fe Formal name: Iron, serum Related tests: Ferritin ; TIBC, UIBC and Transferrin ; Hemoglobin ; Hematocrit ; Complete Blood Count ; Reticulocyte Count ; Zinc Protoporphyrin ; Iron Tests ; Soluble Transferrin Receptor ... I should know? How is it used? Serum iron, total iron-binding capacity (TIBC) , and/or ...

  4. Iron Absorption in Drosophila melanogaster

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    Fanis Missirlis

    2013-05-01

    Full Text Available The way in which Drosophila melanogaster acquires iron from the diet remains poorly understood despite iron absorption being of vital significance for larval growth. To describe the process of organismal iron absorption, consideration needs to be given to cellular iron import, storage, export and how intestinal epithelial cells sense and respond to iron availability. Here we review studies on the Divalent Metal Transporter-1 homolog Malvolio (iron import, the recent discovery that Multicopper Oxidase-1 has ferroxidase activity (iron export and the role of ferritin in the process of iron acquisition (iron storage. We also describe what is known about iron regulation in insect cells. We then draw upon knowledge from mammalian iron homeostasis to identify candidate genes in flies. Questions arise from the lack of conservation in Drosophila for key mammalian players, such as ferroportin, hepcidin and all the components of the hemochromatosis-related pathway. Drosophila and other insects also lack erythropoiesis. Thus, systemic iron regulation is likely to be conveyed by different signaling pathways and tissue requirements. The significance of regulating intestinal iron uptake is inferred from reports linking Drosophila developmental, immune, heat-shock and behavioral responses to iron sequestration.

  5. Iron Absorption in Drosophila melanogaster

    Science.gov (United States)

    Mandilaras, Konstantinos; Pathmanathan, Tharse; Missirlis, Fanis

    2013-01-01

    The way in which Drosophila melanogaster acquires iron from the diet remains poorly understood despite iron absorption being of vital significance for larval growth. To describe the process of organismal iron absorption, consideration needs to be given to cellular iron import, storage, export and how intestinal epithelial cells sense and respond to iron availability. Here we review studies on the Divalent Metal Transporter-1 homolog Malvolio (iron import), the recent discovery that Multicopper Oxidase-1 has ferroxidase activity (iron export) and the role of ferritin in the process of iron acquisition (iron storage). We also describe what is known about iron regulation in insect cells. We then draw upon knowledge from mammalian iron homeostasis to identify candidate genes in flies. Questions arise from the lack of conservation in Drosophila for key mammalian players, such as ferroportin, hepcidin and all the components of the hemochromatosis-related pathway. Drosophila and other insects also lack erythropoiesis. Thus, systemic iron regulation is likely to be conveyed by different signaling pathways and tissue requirements. The significance of regulating intestinal iron uptake is inferred from reports linking Drosophila developmental, immune, heat-shock and behavioral responses to iron sequestration. PMID:23686013

  6. Shelf-to-basin iron shuttling enhances vivianite formation in deep Baltic Sea sediments

    Science.gov (United States)

    Reed, Daniel C.; Gustafsson, Bo G.; Slomp, Caroline P.

    2016-01-01

    Coastal hypoxia is a growing and persistent problem largely attributable to enhanced terrestrial nutrient (i.e., nitrogen and phosphorus) loading. Recent studies suggest phosphorus removal through burial of iron (II) phosphates, putatively vivianite, plays an important role in nutrient cycling in the Baltic Sea - the world's largest anthropogenic dead zone - yet the dynamics of iron (II) phosphate formation are poorly constrained. To address this, a reactive-transport model was used to reconstruct the diagenetic and depositional history of sediments in the Fårö basin, a deep anoxic and sulphidic region of the Baltic Sea where iron (II) phosphates have been observed. Simulations demonstrate that transport of iron from shelf sediments to deep basins enhances vivianite formation while sulphide concentrations are low, but that pyrite forms preferentially over vivianite when sulphate reduction intensifies due to elevated organic loading. Episodic reoxygenation events, associated with major inflows of oxic waters, encourage the retention of iron oxyhydroxides and iron-bound phosphorus in sediments, increasing vivianite precipitation as a result. Results suggest that artificial reoxygenation of the Baltic Sea bottom waters could sequester up to 3% of the annual external phosphorus loads as iron (II) phosphates, but this is negligible when compared to potential internal phosphorus loads due to dissolution of iron oxyhydroxides when low oxygen conditions prevail. Thus, enhancing vivianite formation through artificial reoxygenation of deep waters is not a viable engineering solution to eutrophication in the Baltic Sea. Finally, simulations suggest that regions with limited sulphate reduction and hypoxic intervals, such as eutrophic estuaries, could act as important phosphorus sinks by sequestering vivianite. This could potentially alleviate eutrophication in shelf and slope environments.

  7. Glucose-coated superparamagnetic iron oxide nanoparticles prepared by metal vapour synthesis are electively internalized in a pancreatic adenocarcinoma cell line expressing GLUT1 transporter.

    Science.gov (United States)

    Barbaro, Daniele; Di Bari, Lorenzo; Gandin, Valentina; Evangelisti, Claudio; Vitulli, Giovanni; Schiavi, Eleonora; Marzano, Cristina; Ferretti, Anna M; Salvadori, Piero

    2015-01-01

    Iron oxide nanoparticles (IONP) can have a variety of biomedical applications due to their visualization properties through Magnetic Resonance Imaging (MRI) and heating with radio frequency or alternating magnetic fields. In the oncological field, coating IONP with organic compounds to provide specific features and to achieve the ability of binding specific molecular targets appears to be very promising. To take advantage of the high avidity of tumor cells for glucose, we report the development of very small glucose-coated IONP (glc-IONP) by employing an innovative technique, Metal Vapor Synthesis (MVS). Moreover, we tested the internalization of our gl-IONP on a tumor line, BxPC3, over-expressing GLUT 1 transporter. Both glc-IONP and polyvinylpyrrolidone-IONP (PVP-IONP), as control, were prepared with MVS and were tested on BxPC3 at various concentrations. To evaluate the role of GLUT-1 transporter, we also investigated the effect of adding a polyclonal anti-GLUT1 antibody. After proper treatment, the iron value was assessed by atomic absorption spectrometer, reported in mcg/L and expressed in mg of protein. Our IONP prepared with MVS were very small and homogeneously distributed in a narrow range (1.75-3.75 nm) with an average size of 2.7 nm and were super-paramagnetic. Glc-IONP were internalized by BxPC3 cells in a larger amount than PVP-IONP. After 6h of treatment with 50 mcg/mL of IONPs, the content of Fe was 1.5 times higher in glc-IONP-treated cells compared with PVP-IONP-treated cells. After 1h pre-treatment with anti-GLUT1, a reduction of 41% cellular accumulation of glc-IONP was observed. Conversely, the uptake of PVP-IONPs was reduced only by 14% with antibody pretreatment. In conclusion, MVS allowed us to prepare small, homogeneous, super-paramagnetic glc-IONP, which are electively internalized by a tumor line over-expressing GLUT1. Our glc-IONP appear to have many requisites for in vivo use.

  8. Glucose-coated superparamagnetic iron oxide nanoparticles prepared by metal vapour synthesis are electively internalized in a pancreatic adenocarcinoma cell line expressing GLUT1 transporter.

    Directory of Open Access Journals (Sweden)

    Daniele Barbaro

    Full Text Available Iron oxide nanoparticles (IONP can have a variety of biomedical applications due to their visualization properties through Magnetic Resonance Imaging (MRI and heating with radio frequency or alternating magnetic fields. In the oncological field, coating IONP with organic compounds to provide specific features and to achieve the ability of binding specific molecular targets appears to be very promising. To take advantage of the high avidity of tumor cells for glucose, we report the development of very small glucose-coated IONP (glc-IONP by employing an innovative technique, Metal Vapor Synthesis (MVS. Moreover, we tested the internalization of our gl-IONP on a tumor line, BxPC3, over-expressing GLUT 1 transporter. Both glc-IONP and polyvinylpyrrolidone-IONP (PVP-IONP, as control, were prepared with MVS and were tested on BxPC3 at various concentrations. To evaluate the role of GLUT-1 transporter, we also investigated the effect of adding a polyclonal anti-GLUT1 antibody. After proper treatment, the iron value was assessed by atomic absorption spectrometer, reported in mcg/L and expressed in mg of protein. Our IONP prepared with MVS were very small and homogeneously distributed in a narrow range (1.75-3.75 nm with an average size of 2.7 nm and were super-paramagnetic. Glc-IONP were internalized by BxPC3 cells in a larger amount than PVP-IONP. After 6h of treatment with 50 mcg/mL of IONPs, the content of Fe was 1.5 times higher in glc-IONP-treated cells compared with PVP-IONP-treated cells. After 1h pre-treatment with anti-GLUT1, a reduction of 41% cellular accumulation of glc-IONP was observed. Conversely, the uptake of PVP-IONPs was reduced only by 14% with antibody pretreatment. In conclusion, MVS allowed us to prepare small, homogeneous, super-paramagnetic glc-IONP, which are electively internalized by a tumor line over-expressing GLUT1. Our glc-IONP appear to have many requisites for in vivo use.

  9. Amino acid transport in taxonomically diverse cyanobacteria and identification of two genes encoding elements of a neutral amino acid permease putatively involved in recapture of leaked hydrophobic amino acids.

    Science.gov (United States)

    Montesinos, M L; Herrero, A; Flores, E

    1997-02-01

    The activities of uptake of thirteen 14C-labeled amino acids were determined in nine cyanobacteria, including the unicellular strains Synechococcus sp. strain PCC 7942 and Synechocystis sp. strain PCC 6803; the filamentous strain Pseudanabaena sp. strain PCC 6903, and the filamentous, heterocyst-forming strains Anabaena sp. strains PCC 7120 and PCC 7937; Nostoc sp. strains PCC 7413 and PCC 7107; Calothrix sp. strain PCC 7601 (which is a mutant unable to develop heterocysts); and Fischerella muscicola UTEX 1829. Amino acid transport mutants, selected as mutants resistant to some amino acid analogs, were isolated from the Anabaena, Nostoc, Calothrix, and Pseudanabaena strains. All of the tested cyanobacteria bear at least a neutral amino acid transport system, and some strains also bear transport systems specific for basic or acidic amino acids. Two genes, natA and natB, encoding elements (conserved component, NatA, and periplasmic binding protein, NatB) of an ABC-type permease for neutral amino acids were identified by insertional mutagenesis of strain PCC 6803 open reading frames from the recently published genomic DNA sequence of this cyanobacterium. DNA sequences homologous to natA and natB from strain PCC 6803 were detected by hybridization in eight cyanobacterial strains tested. Mutants unable to transport neutral amino acids, including natA and natB insertional mutants, accumulated in the extracellular medium a set of amino acids that always included Ala, Val, Phe, Ile, and Leu. A general role for a cyanobacterial neutral amino acid permease in recapture of hydrophobic amino acids leaked from the cells is suggested.

  10. Metallomics approach for the identification of the iron transport protein transferrin in the blood of harbour seals (Phoca vitulina).

    Science.gov (United States)

    Grebe, Mechthild; Pröfrock, Daniel; Kakuschke, Antje; Broekaert, Jose A C; Prange, Andreas

    2010-10-01

    The health status of marine mammals such as harbour seals (Phoca vitulina) represents an indirect but powerful way for the assessment of environmental changes. The present work illustrates the first investigation and characterisation of Tf isolated from blood samples of North Sea harbour seals with a view to using changes in Tf isoform patterns as an additional parameter in extended studies of their health status. Therefore, an HPLC-ICP-MS approach has been developed which allows the highly resolved separation and fractionation of up to eight different Tf isoforms, as well as their sensitive and specific detection on the basis of their characteristic iron content. Molecule-specific detection techniques such as nanoLC-ESI-QTRAP-MS or MALDI-TOF-MS were used as complementary techniques to unambiguously identify the isolated proteins as Tf via cross species protein identification and to further characterise the molecular weight as well as the sialic acid content, which is responsible for the elution behaviour of the different isoforms during their ion exchange separation. A molecular mass above 80 kDa has been measured for the different seal Tf isoforms, which is in good agreement with the known molecular mass in other mammalian species, while the estimated pI of the different isoforms indicates some differences in comparison to other species. A number of homologies to known Tf sequences have been observed, which finally allows the cross species protein identification. The combined metallomics orientated analytical approach, which includes the complementary application of element and molecule-specific detection techniques, opens up interesting possibilities for the fast and targeted isolation and identification of a diagnostically relevant metal containing protein from an un-sequenced mammalian species prior to its utilisation in extended studies.

  11. Foliar-applied glyphosate substantially reduced uptake and transport of iron and manganese in sunflower (Helianthus annuus L.) plants.

    Science.gov (United States)

    Eker, Selim; Ozturk, Levent; Yazici, Atilla; Erenoglu, Bulent; Romheld, Volker; Cakmak, Ismail

    2006-12-27

    Evidence clearly shows that cationic micronutrients in spray solutions reduce the herbicidal effectiveness of glyphosate for weed control due to the formation of metal-glyphosate complexes. The formation of these glyphosate-metal complexes in plant tissue may also impair micronutrient nutrition of nontarget plants when exposed to glyphosate drift or glyphosate residues in soil. In the present study, the effects of simulated glyphosate drift on plant growth and uptake, translocation, and accumulation (tissue concentration) of iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu) were investigated in sunflower (Helianthus annuus L.) plants grown in nutrient solution under controlled environmental conditions. Glyphosate was sprayed on plant shoots at different rates between 1.25 and 6.0% of the recommended dosage (i.e., 0.39 and 1.89 mM glyphosate isopropylamine salt). Glyphosate applications significantly decreased root and shoot dry matter production and chlorophyll concentrations of young leaves and shoot tips. The basal parts of the youngest leaves and shoot tips were severely chlorotic. These effects became apparent within 48 h after the glyphosate spray. Glyphosate also caused substantial decreases in leaf concentration of Fe and Mn while the concentration of Zn and Cu was less affected. In short-term uptake experiments with radiolabeled Fe (59Fe), Mn (54Mn), and Zn (65Zn), root uptake of 59Fe and 54Mn was significantly reduced in 12 and 24 h after application of 6% of the recommended dosage of glyphosate, respectively. Glyphosate resulted in almost complete inhibition of root-to-shoot translocation of 59Fe within 12 h and 54Mn within 24 h after application. These results suggest that glyphosate residues or drift may result in severe impairments in Fe and Mn nutrition of nontarget plants, possibly due to the formation of poorly soluble glyphosate-metal complexes in plant tissues and/or rhizosphere interactions.

  12. An Arabidopsis ABC Transporter Mediates Phosphate Deficiency-Induced Remodeling of Root Architecture by Modulating Iron Homeostasis in Roots.

    Science.gov (United States)

    Dong, Jinsong; Piñeros, Miguel A; Li, Xiaoxuan; Yang, Haibing; Liu, Yu; Murphy, Angus S; Kochian, Leon V; Liu, Dong

    2017-02-13

    The remodeling of root architecture is a major developmental response of plants to phosphate (Pi) deficiency and is thought to enhance a plant's ability to forage for the available Pi in topsoil. The underlying mechanism controlling this response, however, is poorly understood. In this study, we identified an Arabidopsis mutant, hps10 (hypersensitive to Pi starvation 10), which is morphologically normal under Pi sufficient condition but shows increased inhibition of primary root growth and enhanced production of lateral roots under Pi deficiency. hps10 is a previously identified allele (als3-3) of the ALUMINUM SENSITIVE3 (ALS3) gene, which is involved in plant tolerance to aluminum toxicity. Our results show that ALS3 and its interacting protein AtSTAR1 form an ABC transporter complex in the tonoplast. This protein complex mediates a highly electrogenic transport in Xenopus oocytes. Under Pi deficiency, als3 accumulates higher levels of Fe(3+) in its roots than the wild type does. In Arabidopsis, LPR1 (LOW PHOSPHATE ROOT1) and LPR2 encode ferroxidases, which when mutated, reduce Fe(3+) accumulation in roots and cause root growth to be insensitive to Pi deficiency. Here, we provide compelling evidence showing that ALS3 cooperates with LPR1/2 to regulate Pi deficiency-induced remodeling of root architecture by modulating Fe homeostasis in roots.

  13. Influence of Iron Supplementation on DMT1 (IRE)-induced Transport of Lead by Brain Barrier Systems in vivo

    Institute of Scientific and Technical Information of China (English)

    AN Dai Zhi; AI Jun Tao; FANG Hong Juan; SUN Ru Bao; SHI Yun; WANG Li Li; WANG Qiang

    2015-01-01

    Objective To investigate the potential involvement of DMT1 (IRE) protein in the brain vascular system in vivo during Pb exposure. Methods Three groups of male Sprague-Dawley rats were exposed to Pb in drinking water, among which two groups were concurrently administered by oral gavage once every other day as the low and high Fe treatment group, respectively, for 6 weeks. At the same time, the group only supplied with high Fe was also set as a reference. The animals were decapitated, then brain capillary-rich fraction was isolate from cerebral cortex. Western blot method was used to identify protein expression, and RT-PCR to detect the change of the mRNA. Results Pb exposure significantly increased Pb concentrations in cerebral cortex. Low Fe dose significantly reduced the cortex Pb levels, However, high Fe dose increased the cortex Pb levels. Interestingly, changes of DMT1 (IRE) protein in brain capillary-rich fraction were highly related to the Pb level, but those of DMT1 (IRE) mRNA were not significantly different. Moreover, the consistent changes in the levels of p-ERK1/2 or IRP1 with the changes in the levels of DMT1 (IRE). Conclusion These results suggest that Pb is transported into the brain through DMT1 (IRE), and the ERK MAPK pathway is involved in DMT1 (IRE)-mediated transport regulation in brain vascular system in vivo.

  14. Les effets des interfaces sur les proprietes magnetiques et de transport des multicouches nickel/iron et cobalt/silver

    Science.gov (United States)

    Veres, Teodor

    Cette these est consacree a l'etude de l'evolution structurale des proprietes magnetiques et de transport des multicouches Ni/Fe et nanostructures a base de Co et de l'Ag. Dans une premiere partie, essentiellement bibliographique, nous introduisons quelques concepts de base relies aux proprietes magnetiques et de transport des multicouches metalliques. Ensuite, nous presentons une breve description des methodes d'analyse des resultats. La deuxieme partie est consacree a l'etude des proprietes magnetiques et de transport des multicouches ferromagnetiques/ferromagnetiques Ni/Fe. Nous montrerons qu'une interpretation coherente de ces proprietes necessite la prise en consideration des effets des interfaces. Nous nous attacherons a mettre en evidence, a evaluer et a etudier les effets de ces interfaces ainsi que leur evolution, et ce, suite a des traitements thermiques tel que le depot a temperature elevee et l'irradiation ionique. Les analyses correlees de la structure et de la magnetoresistance nous permettront d'emettre des conclusions sur l'influence des couches tampons entre l'interface et le substrat ainsi qu'entre les couches elles-memes sur le comportement magnetique des couches F/F. La troisieme partie est consacree aux systemes a Magneto-Resistance Geante (MRG) a base de Co et Ag. Nous allons etudier l'evolution de la microstructure suite a l'irradiation avec des ions Si+ ayant une energie de 1 MeV, ainsi que les effets de ces changements sur le comportement magnetique. Cette partie debutera par l'analyse des proprietes d'une multicouche hybride, intermediaire entre les multicouches et les materiaux granulaires. Nous analyserons a l'aide des mesures de diffraction, de relaxation superparamagnetique et de magnetoresistance, les evolutions structurales produites par l'irradiation ionique. Nous etablirons des modeles qui nous aideront a interpreter les resultats pour une serie des multicouches qui couvrent un large eventail de differents comportements magnetiques

  15. Mass transport of carbon in one and two phase iron-nickel alloys in a temperature gradient

    Energy Technology Data Exchange (ETDEWEB)

    Okafor, I.C.I.; Carlson, O.N.; Martin, D.M.

    1983-10-01

    The flux of carbon atoms induced by an applied temperature gradient on a specimen was investigated for an Fe-32.5 wt pct Ni alloy for six carbon concentrations. Carbon was found to migrate to the higher temperature region in the low carbon single phase alloys. However, in the higher carbon alloys an abrupt jump in carbon concentrations results when a portion of the specimen is in a two-phase region while the portion in the one-phase region exhibits the usual solute migration toward the higher temperature. A value of -12.2 + or - 0.4 kJ mol/sup -1/ was obtained for the heat of transport of carbon in the ..gamma..-phase Fe-Ni alloys for a wide range of carbon concentrations. A model for diffusion and thermotransport in multiphase systems is presented to explain the observed results.

  16. Reaction-Based Reactive Transport Modeling of Iron Reduction and Uranium Immobilization at Area 2 of the NABIR Field Research Center

    Energy Technology Data Exchange (ETDEWEB)

    Burgos, W.D.

    2009-09-02

    This report summarizes research conducted in conjunction with a project entitled “Reaction-Based Reactive Transport Modeling of Iron Reduction and Uranium Immobilization at Area 2 of the NABIR Field Research Center”, which was funded through the Integrative Studies Element of the former NABIR Program (now the Environmental Remediation Sciences Program) within the Office of Biological and Environmental Research. Dr. William Burgos (The Pennsylvania State University) was the overall PI/PD for the project, which included Brian Dempsey (Penn State), Gour-Tsyh (George) Yeh (Central Florida University), and Eric Roden (formerly at The University of Alabama, now at the University of Wisconsin) as separately-funded co-PIs. The project focused on development of a mechanistic understanding and quantitative models of coupled Fe(III)/U(VI) reduction in FRC Area 2 sediments. The work builds on our previous studies of microbial Fe(III) and U(VI) reduction, and was directly aligned with the Scheibe et al. ORNL FRC Field Project at Area 2.

  17. Protein Hydrolysates as Promoters of Non-Haem Iron Absorption

    Directory of Open Access Journals (Sweden)

    Yanan Li

    2017-06-01

    Full Text Available Iron (Fe is an essential micronutrient for human growth and health. Organic iron is an excellent iron supplement due to its bioavailability. Both amino acids and peptides improve iron bioavailability and absorption and are therefore valuable components of iron supplements. This review focuses on protein hydrolysates as potential promoters of iron absorption. The ability of protein hydrolysates to chelate iron is thought to be a key attribute for the promotion of iron absorption. Iron-chelatable protein hydrolysates are categorized by their absorption forms: amino acids, di- and tri-peptides and polypeptides. Their structural characteristics, including their size and amino acid sequence, as well as the presence of special amino acids, influence their iron chelation abilities and bioavailabilities. Protein hydrolysates promote iron absorption by keeping iron soluble, reducing ferric iron to ferrous iron, and promoting transport across cell membranes into the gut. We also discuss the use and relative merits of protein hydrolysates as iron supplements.

  18. Escherichia coli YqjA, a Member of the Conserved DedA/Tvp38 Membrane Protein Family, Is a Putative Osmosensing Transporter Required for Growth at Alkaline pH.

    Science.gov (United States)

    Kumar, Sujeet; Doerrler, William T

    2015-07-01

    The ability to persist and grow under alkaline conditions is an important characteristic of many bacteria. In order to survive at alkaline pH, Escherichia coli must maintain a stable cytoplasmic pH of about 7.6. Membrane cation/proton antiporters play a major role in alkaline pH homeostasis by catalyzing active inward proton transport. The DedA/Tvp38 family is a highly conserved membrane protein family of unknown function present in most sequenced genomes. YqjA and YghB are members of the E. coli DedA family with 62% amino acid identity and partially redundant functions. We have shown that E. coli with ΔyqjA and ΔyghB mutations cannot properly maintain the proton motive force (PMF) and is compromised in PMF-dependent drug efflux and other PMF-dependent functions. Furthermore, the functions of YqjA and YghB are dependent upon membrane-embedded acidic amino acids, a hallmark of several families of proton-dependent transporters. Here, we show that the ΔyqjA mutant (but not ΔyghB) cannot grow under alkaline conditions (ranging from pH 8.5 to 9.5), unlike the parent E. coli. Overexpression of yqjA restores growth at alkaline pH, but only when more than ∼100 mM sodium or potassium is present in the growth medium. Increasing the osmotic pressure by the addition of sucrose enhances the ability of YqjA to support growth under alkaline conditions in the presence of low salt concentrations, consistent with YqjA functioning as an osmosensor. We suggest that YqjA possesses proton-dependent transport activity that is stimulated by osmolarity and that it plays a significant role in the survival of E. coli at alkaline pH. The ability to survive under alkaline conditions is important for many species of bacteria. Escherichia coli can grow at pH 5.5 to 9.5 while maintaining a constant cytoplasmic pH of about 7.6. Under alkaline conditions, bacteria rely upon proton-dependent transporters to maintain a constant cytoplasmic pH. The DedA/Tvp38 protein family is a highly conserved

  19. Gene expression profiling and phenotype analyses of S. cerevisiae in response to changing copper reveals six genes with new roles in copper and iron metabolism.

    Science.gov (United States)

    van Bakel, Harm; Strengman, Eric; Wijmenga, Cisca; Holstege, Frank C P

    2005-08-11

    Exhaustive microarray time course analyses of Saccharomyces cerevisiae during copper starvation and copper excess reveal new aspects of metal-induced gene regulation. Aside from identifying targets of established copper- and iron-responsive transcription factors, we find that genes encoding mitochondrial proteins are downregulated and that copper-independent iron transport genes are preferentially upregulated, both during prolonged copper deprivation. The experiments also suggest the presence of a small regulatory iron pool that links copper and iron responses. One hundred twenty-eight genes with putative roles in metal metabolism were further investigated by several systematic phenotype screens. Of the novel phenotypes uncovered, hsp12-Delta and arn1-Delta display increased sensitivity to copper, cyc1-Delta and crr1-Delta show resistance to high copper, vma13-Delta exhibits increased sensitivity to iron deprivation, and pep12-Delta results in reduced growth in high copper and low iron. Besides revealing new components of eukaryotic metal trafficking pathways, the results underscore the previously determined intimate links between iron and copper metabolism and mitochondrial and vacuolar function in metal trafficking. The analyses further suggest that copper starvation can specifically lead to downregulation of respiratory function to preserve iron and copper for other cellular processes.

  20. The Pharmacokinetics and Pharmacodynamics of Iron Preparations

    Directory of Open Access Journals (Sweden)

    Susanna Burckhardt

    2011-01-01

    Full Text Available Standard approaches are not appropriate when assessing pharmacokinetics of iron supplements due to the ubiquity of endogenous iron, its compartmentalized sites of action, and the complexity of the iron metabolism. The primary site of action of iron is the erythrocyte, and, in contrast to conventional drugs, no drug-receptor interaction takes place. Notably, the process of erythropoiesis, i.e., formation of new erythrocytes, takes 3−4 weeks. Accordingly, serum iron concentration and area under the curve (AUC are clinically irrelevant for assessing iron utilization. Iron can be administered intravenously in the form of polynuclear iron(III-hydroxide complexes with carbohydrate ligands or orally as iron(II (ferrous salts or iron(III (ferric complexes. Several approaches have been employed to study the pharmacodynamics of iron after oral administration. Quantification of iron uptake from radiolabeled preparations by the whole body or the erythrocytes is optimal, but alternatively total iron transfer can be calculated based on known elimination rates and the intrinsic reactivity of individual preparations. Degradation kinetics, and thus the safety, of parenteral iron preparations are directly related to the molecular weight and the stability of the complex. High oral iron doses or rapid release of iron from intravenous iron preparations can saturate the iron transport system, resulting in oxidative stress with adverse clinical and subclinical consequences. Appropriate pharmacokinetics and pharmacodynamics analyses will greatly assist our understanding of the likely contribution of novel preparations to the management of anemia.

  1. The pharmacokinetics and pharmacodynamics of iron preparations.

    Science.gov (United States)

    Geisser, Peter; Burckhardt, Susanna

    2011-01-04

    Standard approaches are not appropriate when assessing pharmacokinetics of iron supplements due to the ubiquity of endogenous iron, its compartmentalized sites of action, and the complexity of the iron metabolism. The primary site of action of iron is the erythrocyte, and, in contrast to conventional drugs, no drug-receptor interaction takes place. Notably, the process of erythropoiesis, i.e., formation of new erythrocytes, takes 3-4 weeks. Accordingly, serum iron concentration and area under the curve (AUC) are clinically irrelevant for assessing iron utilization. Iron can be administered intravenously in the form of polynuclear iron(III)-hydroxide complexes with carbohydrate ligands or orally as iron(II) (ferrous) salts or iron(III) (ferric) complexes. Several approaches have been employed to study the pharmacodynamics of iron after oral administration. Quantification of iron uptake from radiolabeled preparations by the whole body or the erythrocytes is optimal, but alternatively total iron transfer can be calculated based on known elimination rates and the intrinsic reactivity of individual preparations. Degradation kinetics, and thus the safety, of parenteral iron preparations are directly related to the molecular weight and the stability of the complex. High oral iron doses or rapid release of iron from intravenous iron preparations can saturate the iron transport system, resulting in oxidative stress with adverse clinical and subclinical consequences. Appropriate pharmacokinetics and pharmacodynamics analyses will greatly assist our understanding of the likely contribution of novel preparations to the management of anemia.

  2. HIGHWAY INFRASTRUCTURE FOCUS AREA NEXT-GENERATION INFRASTRUCTURE MATERIALS VOLUME I - TECHNICAL PROPOSAL & MANAGEMENTENHANCEMENT OF TRANSPORTATION INFRASTRUCTURE WITH IRON-BASED AMORPHOUS-METAL AND CERAMIC COATINGS

    Energy Technology Data Exchange (ETDEWEB)

    Farmer, J C

    2007-12-04

    The infrastructure for transportation in the United States allows for a high level of mobility and freight activity for the current population of 300 million residents, and several million business establishments. According to a Department of Transportation study, more than 230 million motor vehicles, ships, airplanes, and railroads cars were used on 6.4 million kilometers (4 million miles) of highways, railroads, airports, and waterways in 1998. Pipelines and storage tanks were considered to be part of this deteriorating infrastructure. The annual direct cost of corrosion in the infrastructure category was estimated to be approximately $22.6 billion in 1998. There were 583,000 bridges in the United States in 1998. Of this total, 200,000 bridges were steel, 235,000 were conventional reinforced concrete, 108,000 bridges were constructed using pre-stressed concrete, and the balance was made using other materials of construction. Approximately 15 percent of the bridges accounted for at this point in time were structurally deficient, primarily due to corrosion of steel and steel reinforcement. Iron-based amorphous metals, including SAM2X5 (Fe{sub 49.7}Cr{sub 17.7}Mn{sub 1.9}Mo{sub 7.4}W{sub 1.6}B{sub 15.2}C{sub 3.8}Si{sub 2.4}) and SAM1651 (Fe{sub 48}Mo{sub 14}Cr{sub 15}Y{sub 2}C{sub 15}B{sub 6}) have been developed, and have very good corrosion resistance. These materials have been prepared as a melt-spun ribbons, as well as gas atomized powders and thermal-spray coatings. During electrochemical testing in several environments, including seawater at 90 C, the passive film stabilities of these materials were found to be comparable to that of more expensive high-performance alloys, based on electrochemical measurements of the passive film breakdown potential and general corrosion rates. These materials also performed very well in standard salt fog tests. Chromium (Cr), molybdenum (Mo) and tungsten (W) provided corrosion resistance, and boron (B) enabled glass formation

  3. Identification of high levels of phytochelatins, glutathione and cadmium in the phloem sap of Brassica napus. A role for thiol-peptides in the long-distance transport of cadmium and the effect of cadmium on iron translocation.

    Science.gov (United States)

    Mendoza-Cózatl, David G; Butko, Emerald; Springer, Franziska; Torpey, Justin W; Komives, Elizabeth A; Kehr, Julia; Schroeder, Julian I

    2008-04-01

    Phytochelatins (PCs) are glutathione-derived peptides that function in heavy metal detoxification in plants and certain fungi. Recent research in Arabidopsis has shown that PCs undergo long-distance transport between roots and shoots. However, it remains unknown which tissues or vascular systems, xylem or phloem, mediate PC translocation and whether PC transport contributes to physiologically relevant long-distance transport of cadmium (Cd) between shoots and roots. To address these questions, xylem and phloem sap were obtained from Brassica napus to quantitatively analyze which thiol species are present in response to Cd exposure. High levels of PCs were identified in the phloem sap within 24 h of Cd exposure using combined mass spectrometry and fluorescence HPLC analyses. Unexpectedly, the concentration of Cd was more than four-fold higher in phloem sap compared to xylem sap. Cadmium exposure dramatically decreased iron levels in xylem and phloem sap whereas other essential heavy metals such as zinc and manganese remained unchanged. Data suggest that Cd inhibits vascular loading of iron but not nicotianamine. The high ratios [PCs]/[Cd] and [glutathione]/[Cd] in the phloem sap suggest that PCs and glutathione (GSH) can function as long-distance carriers of Cd. In contrast, only traces of PCs were detected in xylem sap. Our results suggest that, in addition to directional xylem Cd transport, the phloem is a major vascular system for long-distance source to sink transport of Cd as PC-Cd and glutathione-Cd complexes.

  4. Iron and iron-related proteins in asbestosis.

    Science.gov (United States)

    ABSTRACT: We tested the postulate that iron homeostasis is altered among patients diagnosed to have asbestosis. Lung tissue from six individuals diagnosed to have had asbestosis at autopsy was stained for iron, ferritin, divalent metal transporter 1 (DMT1), and ferroportin 1 (FP...

  5. Iron and iron-related proteins in asbestosis.

    Science.gov (United States)

    ABSTRACT: We tested the postulate that iron homeostasis is altered among patients diagnosed to have asbestosis. Lung tissue from six individuals diagnosed to have had asbestosis at autopsy was stained for iron, ferritin, divalent metal transporter 1 (DMT1), and ferroportin 1 (FP...

  6. Insight from TonB hybrid proteins into the mechanism of iron transport through the outer membrane.

    Science.gov (United States)

    Kaserer, Wallace A; Jiang, Xiaoxu; Xiao, Qiaobin; Scott, Daniel C; Bauler, Matthew; Copeland, Daniel; Newton, Salete M C; Klebba, Phillip E

    2008-06-01

    We created hybrid proteins to study the functions of TonB. We first fused the portion of Escherichia coli tonB that encodes the C-terminal 69 amino acids (amino acids 170 to 239) of TonB downstream from E. coli malE (MalE-TonB69C). Production of MalE-TonB69C in tonB(+) bacteria inhibited siderophore transport. After overexpression and purification of the fusion protein on an amylose column, we proteolytically released the TonB C terminus and characterized it. Fluorescence spectra positioned its sole tryptophan (W213) in a weakly polar site in the protein interior, shielded from quenchers. Affinity chromatography showed the binding of the TonB C-domain to other proteins: immobilized TonB-dependent (FepA and colicin B) and TonB-independent (FepADelta3-17, OmpA, and lysozyme) proteins adsorbed MalE-TonB69C, revealing a general affinity of the C terminus for other proteins. Additional constructions fused full-length TonB upstream or downstream of green fluorescent protein (GFP). TonB-GFP constructs had partial functionality but no fluorescence; GFP-TonB fusion proteins were functional and fluorescent. The activity of the latter constructs, which localized GFP in the cytoplasm and TonB in the cell envelope, indicate that the TonB N terminus remains in the inner membrane during its biological function. Finally, sequence analyses revealed homology in the TonB C terminus to E. coli YcfS, a proline-rich protein that contains the lysin (LysM) peptidoglycan-binding motif. LysM structural mimicry occurs in two positions of the dimeric TonB C-domain, and experiments confirmed that it physically binds to the murein sacculus. Together, these findings infer that the TonB N terminus remains associated with the inner membrane, while the downstream region bridges the cell envelope from the affinity of the C terminus for peptidoglycan. This architecture suggests a membrane surveillance model of action, in which TonB finds occupied receptor proteins by surveying the underside of

  7. Iron deficiency induces changes in riboflavin secretion and the mitochondrial electron transport chain in hairy roots of Hyoscyamus albus.

    Science.gov (United States)

    Higa, Ataru; Mori, Yuko; Kitamura, Yoshie

    2010-07-15

    Hyoscyamus albus hairy roots secrete riboflavin under Fe-deficient conditions. To determine whether this secretion was linked to an enhancement of respiration, both riboflavin secretion and the reduction of 2,3,5-triphenyltetrazolium chloride (TTC), as a measure of respiration activity, were determined in hairy roots cultured under Fe-deficient and Fe-replete conditions, with or without aeration. Appreciable TTC-reducing activity was detected at the root tips, at the bases of lateral roots and in internal tissues, notably the vascular system. TTC-reducing activity increased under Fe deficiency and this increase occurred in concert with riboflavin secretion and was more apparent under aeration. Riboflavin secretion was not apparent under Fe-replete conditions. In order to examine which elements of the mitochondrial electron transport chain might be involved, the effects of the respiratory inhibitors, barbiturate, dicoumarol, malonic acid, antimycin, KCN and salicylhydroxamic acid (SHAM) were investigated. Under Fe-deficient conditions, malonic acid affected neither root growth, TTC-reducing activity nor riboflavin secretion, whereas barbiturate and SHAM inhibited only root growth and TTC-reducing activity, respectively, and the other compounds variously inhibited growth and TTC-reducing activity. Riboflavin secretion was decreased, in concert with TTC-reducing activity, by dicoumarol, antimycin and KCN, but not by SHAM. In Fe-replete roots, all inhibitors which reduced riboflavin secretion in Fe-deficient roots showed somewhat different effects: notably, antimycin and KCN did not significantly inhibit TTC-reducing activity and the inhibition by dicoumarol was much weaker in Fe-replete roots. Combined treatment with KCN and SHAM also revealed that Fe-deficient and Fe-replete roots reduced TTC in different ways. A decrease in the Fe content of mitochondria in Fe-deficient roots was confirmed. Overall, the results suggest that, under conditions of Fe deficiency in H

  8. 缺铁条件下酵母中铁转运转录水平的研究进展%Advances of Gene Expression in Iron Transport Response to Iron Deprivation in Saccharomyces cerevisiae

    Institute of Scientific and Technical Information of China (English)

    王俐勇; 赵君朋

    2013-01-01

    As an essential element, iron plays an important role in many cellular functions and biochemical processes. Although being generally abundant in most soil, soluble irons are deficient for most plants in alkaline or neutral soils. In this case, iron stress is full of adversity for plant growth. In this paper, we summarized the research progress on activation of iron uptake systems, mobilization of intracellular iron, and regulation of iron related metabolic activities in yeast cells. Future research prospects are also discussed.%铁作为生物体内重要元素,在很多细胞功能以及生化过程中具有重要作用。尽管多数土壤中铁含量较为丰富,但在碱性或中性土壤中可以吸收利用的可溶性铁量却无法满足植物需要。在这种情况下所导致的缺铁胁迫不利于植物生长发育。本文从铁吸收系统的激活、胞内铁源的启动和铁相关代谢活动的调控三个方面阐述了酵母细胞中铁转运转录水平上的研究现状,最后展望了其发展前景。

  9. Iron deficiency.

    Science.gov (United States)

    Scrimshaw, N S

    1991-10-01

    The world's leading nutritional problem is iron deficiency. 66% of children and women aged 15-44 years in developing countries have it. Further, 10-20% of women of childbearing age in developed countries are anemic. Iron deficiency is identified with often irreversible impairment of a child's learning ability. It is also associated with low capacity for adults to work which reduces productivity. In addition, it impairs the immune system which reduces the body's ability to fight infection. Iron deficiency also lowers the metabolic rate and the body temperature when exposed to cold. Hemoglobin contains nearly 73% of the body's iron. This iron is always being recycled as more red blood cells are made. The rest of the needed iron does important tasks for the body, such as binds to molecules that are reservoirs of oxygen for muscle cells. This iron comes from our diet, especially meat. Even though some plants, such as spinach, are high in iron, the body can only absorb 1.4-7% of the iron in plants whereas it can absorb 20% of the iron in red meat. In many developing countries, the common vegetarian diets contribute to high rates of iron deficiency. Parasitic diseases and abnormal uterine bleeding also promote iron deficiency. Iron therapy in anemic children can often, but not always, improve behavior and cognitive performance. Iron deficiency during pregnancy often contributes to maternal and perinatal mortality. Yet treatment, if given to a child in time, can lead to normal growth and hinder infections. However, excess iron can be damaging. Too much supplemental iron in a malnourished child promotes fatal infections since the excess iron is available for the pathogens use. Many countries do not have an effective system for diagnosing, treating, and preventing iron deficiency. Therefore a concerted international effort is needed to eliminate iron deficiency in the world.

  10. Serum-induced iron-acquisition systems and TonB contribute to virulence in Klebsiella pneumoniae causing primary pyogenic liver abscess.

    Science.gov (United States)

    Hsieh, Pei-Fang; Lin, Tzu-Lung; Lee, Cha-Ze; Tsai, Shih-Feng; Wang, Jin-Town

    2008-06-15

    Klebsiella pneumoniae has become the predominant pathogen causing primary pyogenic liver abscess (PLA). K. pneumoniae was stimulated by human serum, and gene expression was analyzed by microarray. Three putative iron acquisition systems, Yersinia high-pathogenicity island (HPI), iucABCDiutA, and iroA(iroNDCB), that increased in expression and predominated in PLA-associated K. pneumoniae strains were identified. By use of siderophore uptake assays, these 3 systems were confirmed to be siderophore-dependent iron acquisition systems. Only the irp2-iuc-iroA triple mutant showed decreased virulence in mice. Full-genome analysis of K. pneumoniae strain NTUH-K2044 identified 10 putative iron uptake systems. Seven of these 10 systems were TonB dependent, including Yersinia HPI, iucABCDiutA, and iroA. A tonB deletion mutant was demonstrated to have profound attenuation of virulence. Immunization with the tonB mutant resulted in seroconversion of extracellular polysaccharide antibodies and protective efficacy against subsequent exposure to the parental strain. Iron uptake systems were the genes in K. pneumoniae that were highly up-regulated in response to sera. Although there are multiple iron transporter systems in NTUH-K2044, a mutation in all 3 loci (irp2, iuc, and iroA) is necessary to decrease virulence. The tonB mutant is a potential vaccine candidate because it can induce a significant protective immune response against challenge with a wild-type strain.

  11. Iron metabolism in the mononuclear phagocyte system

    Institute of Scientific and Technical Information of China (English)

    Weina Kong; Xianglin Duan; Zhenhua Shi; Yanzhong Chang

    2008-01-01

    The maintenance of body iron homeostasis requires the coordination of multiple regulatory mechanisms of iron metabolism.The mononuclear phagocyte system (MPS,composed of monocytes,macrophages,and their precursor cells) is crucial in the maintenance of iron homeostasis.Recycling of iron is carried out by specialized macrophages via engulfment of aged erythrocytes.The iron stores of macrophages depend on the levels of recovered and exported iron.However,the molecular mechanisms underlying iron homeostasis in macrophages are poorly understood.Recent studies characterizing the function and regulation of natural resistance-associated macrophage protein 1 (Nrampl),divalent metal transporter 1 (DMTI),HLA-linked hemechromatosis gene (HFE),ferroportin 1 (FPN1),and hepcidin are rapidly expanding our knowledge on the molecular level of MPS iron handling.These studies are deepening our understanding about the molecular mechanism of iron homeostasis and iron-related diseases.

  12. The involvement of OsPHO1;1 in the regulation of iron transport through integration of phosphate and zinc deficiency signalling

    Directory of Open Access Journals (Sweden)

    Chorpet esaenchai

    2016-04-01

    Full Text Available Plants survival depends on their ability to cope with multiple nutrient stresses that often occur simultaneously, such as the limited availability of essential elements inorganic phosphate (Pi, zinc (Zn and iron (Fe. Previous research has provided information on the genes involved in efforts by plants to maintain homeostasis when a single nutrient (Pi, Zn or Fe is depleted. Recent findings on nutritional stress suggest that plant growth capacity is influenced by a complex tripartite interaction between Pi, Zn and Fe homeostasis. However, despite its importance, how plants integrate multiple nutritional stimuli into complex developmental programs, and which genes are involved in this tripartite (Pi ZnFe interaction is still not clear. The aim of this study was to examine the physiological and molecular responses of rice (Oriza sativa L. to a combination of Pi, Zn and/or Fe deficiency stress conditions. Results showed that Fe deficiency had the most drastic single-nutrient effect on biomass, while the Zn deficiency-effect depended on the presence of Pi in the medium. Interestingly, the observed negative effect of Fe starvation was alleviated by concomitant Pi or PiZn depletion. Members of the OsPHO1 family showed a differential transcriptional regulation in response PiZnFe combinatory stress conditions. Particularly, the transcripts of the OsPHO1;1 sense and its natural antisense cis-NatPHO1;1 showed the highest accumulation under PiZn deficiency. In this condition, the Ospho1;1 mutants showed over-accumulation of Fe in roots compared to wild type plants. These data reveal coordination between pathways involved in Fe transport and PiZn signalling in rice which involves the OsPHO1; 1, and support the hypothesis of a genetic basis for Pi, Zn and Fe signalling interactions in plants.

  13. Final Report - Novel investigation of iron cross sections via spherical shell transmission measurements and particle transport calculations for material embrittlement studies.

    Energy Technology Data Exchange (ETDEWEB)

    Steven M. Grimes; Thomas N. Massey; Allan D. Carlson; James M. Adams; Alireza Haghighat; Michael T. Wenner; Shane R. Gardner

    2003-04-25

    OAK B204 We have been pursuing a multi-year project, funded by the U.S. Department of Energy, to study neutron scattering interactions in iron. The principal objective of this work is to investigate the well-known deficiency that exists for reactor pressure vessel neutron fluence determinations. Specifically, we are using the spherical-shell transmission method, employing iron shells with different thicknesses, and neutron time-of-flight (TOF) measurements of the scattered neutrons, in an effort to precisely determine specific energy regions over which deficiencies in the non-elastic scattering cross section for neutron scattering in iron appear to exist.

  14. Native iron

    DEFF Research Database (Denmark)

    Brooks, Charles Kent

    2015-01-01

    , a situation unique in the Solar System. In such a world, iron metal is unstable and, as we all know, oxidizes to the ferric iron compounds we call 'rust'. If we require iron metal it must be produced at high temperatures by reacting iron ore, usually a mixture of ferrous (Fe2+) and ferric (Fe3+) oxides (Fe2O3......, hematite, or FeO.Fe2O3, magnetite), with carbon in the form of coke. This is carried out in a blast furnace. Although the Earth's core consists of metallic iron, which may also be present in parts of the mantle, this is inaccessible to us, so we must make our own. In West Greenland, however, some almost...... unique examples of iron metal, otherwise called 'native iron' or 'telluric iron', occur naturally....

  15. Impact of carboxymethyl cellulose coating on iron sulphide nanoparticles stability, transport, and mobilization potential of trace metals present in soils and sediment.

    Science.gov (United States)

    Van Koetsem, Frederik; Van Havere, Lynn; Du Laing, Gijs

    2016-03-01

    The stability and transport behaviour of carboxymethyl cellulose (CMC) stabilized iron sulphide (FeS) engineered nanoparticles (ENPs) as well as their concurrent scavenging and mobilization of trace metal contaminants from field-contaminated soils and sediment was studied through a series of batch and column experiments. The synthesized CMC-FeS ENPs were shown to have a hydrodynamic diameter of 154.5 ± 5.8 nm and remained stable in suspension for a prolonged period of time (several weeks) when kept under anaerobic conditions. In the absence of CMC, much larger FeS particles were formed, which quickly aggregated and precipitated within minutes. Batch experiments indicated that the CMC-FeS ENPs have a high affinity for metal contaminants (e.g., Cd, Cr, Cu, Hg, Ni, Pb, and Zn), as high amounts of these trace metals could be retrieved in the aqueous phase after treatment of the soils with the nanoparticles (i.e., up to 29 times more compared to the water-leachable metal contents). Furthermore, batch retention of the nanoparticles by the solid soil phase was low (trace metals, although no clear trend could be observed and metal leaching appeared to depend on the specific element under consideration, the type of extraction liquid, as well as on soil properties. Column breakthrough tests demonstrated that the CMC-FeS ENPs were highly mobile in the tested soil, even without the use of an external pressure (i.e., just via gravitational percolation). Maximal breakthrough of the nanoparticles was observed after approximately 10 or 16 pore volumes (PVs) for 83.3 or 500 mg L(-1) CMC-FeS ENPs, respectively, and only about 7% of the nanoparticles were retained by the soil after 22.7 PVs. Simultaneous elution of trace elements showed that up to 19, 8.7, or 11% of the respective Cd, Pb, or Zn content originally present in the soil was extracted after 22.7 PVs, with initial peaking occurring during the first 5 PVs. Moreover, filtration of the percolates over 0.10 μm (which

  16. Effect of iron limitation and fur gene inactivation on the transcriptional profile of the strict anaerobe Clostridium acetobutylicum.

    Science.gov (United States)

    Vasileva, Delyana; Janssen, Holger; Hönicke, Daniel; Ehrenreich, Armin; Bahl, Hubert

    2012-07-01

    Iron is a nutrient of critical importance for the strict anaerobe Clostridium acetobutylicum, as it is involved in numerous basic cellular functions and metabolic pathways. A gene encoding a putative ferric uptake regulator (Fur) has been identified in the genome of C. acetobutylicum. In this work, we inactivated the fur gene by using insertional mutagenesis. The resultant mutant showed a slow-growing phenotype and enhanced sensitivity to oxidative stress, but essentially no dramatic change in its fermentation pattern. A unique feature of its physiology was the overflowing production of riboflavin. To gain further insights into the role of the Fur protein and the mechanisms for establishment of iron balance in C. acetobutylicum, we characterized and compared the gene-expression profile of the fur mutant and the iron-limitation stimulon of the parental strain. Not surprisingly, a repertoire of iron-transport systems was upregulated in both microarray datasets, suggesting that they are regulated by Fur according to the availability of iron. In addition, iron limitation and inactivation of fur affected the expression of several genes involved in energy metabolism. Among them, two genes, encoding a lactate dehydrogenase and a flavodoxin, were highly induced. In order to support the function of the latter, the ribDBAH operon responsible for riboflavin biosynthesis was also upregulated significantly. Furthermore, the iron-starvation response of C. acetobutylicum involved transcriptional modifications that were not detected in the fur mutant, suggesting that there exist additional mechanisms for adaptation to low-iron environments. Collectively, these results demonstrate that the strict anaerobe C. acetobutylicum senses and responds to availability of iron on multiple levels using a sophisticated system, and that Fur plays an important role in this process.

  17. Combustion iron distribution and deposition

    Science.gov (United States)

    Luo, Chao; Mahowald, N.; Bond, T.; Chuang, P. Y.; Artaxo, P.; Siefert, R.; Chen, Y.; Schauer, J.

    2008-03-01

    Iron is hypothesized to be an important micronutrient for ocean biota, thus modulating carbon dioxide uptake by the ocean biological pump. Studies have assumed that atmospheric deposition of iron to the open ocean is predominantly from mineral aerosols. For the first time we model the source, transport, and deposition of iron from combustion sources. Iron is produced in small quantities during fossil fuel burning, incinerator use, and biomass burning. The sources of combustion iron are concentrated in the industrialized regions and biomass burning regions, largely in the tropics. Model results suggest that combustion iron can represent up to 50% of the total iron deposited, but over open ocean regions it is usually less than 5% of the total iron, with the highest values (ocean biogeochemistry the bioavailability of the iron is important, and this is often estimated by the fraction which is soluble (Fe(II)). Previous studies have argued that atmospheric processing of the relatively insoluble Fe(III) occurs to make it more soluble (Fe(II)). Modeled estimates of soluble iron amounts based solely on atmospheric processing as simulated here cannot match the variability in daily averaged in situ concentration measurements in Korea, which is located close to both combustion and dust sources. The best match to the observations is that there are substantial direct emissions of soluble iron from combustion processes. If we assume observed soluble Fe/black carbon ratios in Korea are representative of the whole globe, we obtain the result that deposition of soluble iron from combustion contributes 20-100% of the soluble iron deposition over many ocean regions. This implies that more work should be done refining the emissions and deposition of combustion sources of soluble iron globally.

  18. 49 CFR 192.275 - Cast iron pipe.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Cast iron pipe. 192.275 Section 192.275... Cast iron pipe. (a) Each caulked bell and spigot joint in cast iron pipe must be sealed with mechanical leak clamps. (b) Each mechanical joint in cast iron pipe must have a gasket made of a...

  19. Alginate-Iron Speciation and Its Effect on In Vitro Cellular Iron Metabolism.

    Directory of Open Access Journals (Sweden)

    Richard D Horniblow

    Full Text Available Alginates are a class of biopolymers with known iron binding properties which are routinely used in the fabrication of iron-oxide nanoparticles. In addition, alginates have been implicated in influencing human iron absorption. However, the synthesis of iron oxide nanoparticles employs non-physiological pH conditions and whether nanoparticle formation in vivo is responsible for influencing cellular iron metabolism is unclear. Thus the aims of this study were to determine how alginate and iron interact at gastric-comparable pH conditions and how this influences iron metabolism. Employing a range of spectroscopic techniques under physiological conditions alginate-iron complexation was confirmed and, in conjunction with aberration corrected scanning transmission electron microscopy, nanoparticles were observed. The results infer a nucleation-type model of iron binding whereby alginate is templating the condensation of iron-hydroxide complexes to form iron oxide centred nanoparticles. The interaction of alginate and iron at a cellular level was found to decrease cellular iron acquisition by 37% (p < 0.05 and in combination with confocal microscopy the alginate inhibits cellular iron transport through extracellular iron chelation with the resulting complexes not internalised. These results infer alginate as being useful in the chelation of excess iron, especially in the context of inflammatory bowel disease and colorectal cancer where excess unabsorbed luminal iron is thought to be a driver of disease.

  20. [Iron metabolism, overview and recent insights].

    Science.gov (United States)

    Omar, S; Feki, M; Kaabachi, N

    2006-01-01

    The paper is an up to date overview of knowledge on iron metabolism that integrate recent findings in this field. Significant advances were made in understanding the implication of protein factors (transporters, enzymes and regulation factors) in iron metabolism, as well as related genetic abnormalities. The research highlighted the complexity of mechanisms in charge of maintaining equilibrium of Fe in the body. The iron is vital to the life of cells, but its presence in excess is rather toxic. Iron is mostly required for hemoglobin synthesis. It is recycled between reticulo-endothelial macrophages and bone marrow that is the main user of iron. Intestinal absorption is a key step in determining iron capital in the body. Its rate is tightly controlled by several factors that act under influence of signals of unknown nature, which indicate iron needs and storage. The IRP/IRE (iron regulatory protein/iron responsive element) system controls cellular uptake, stores and exportation of iron, and heme synthesis. Mitochondrion is a dynamo of iron metabolism, being vital for heme synthesis and iron sulphur cluster genesis. The recent discovery of several mitochondrial proteins involved in iron metabolism resulted in better understanding mitochondrial iron movement, storage and exchange. Nevertheless, much remains to be known on the role of some actors such as HFE protein, hepcidin, hemojuvelin and transferrin receptor 2, and to determine the nature and mechanisms of signals regulating iron level in the body.

  1. Putative cryptoendolithic life in Devonian pillow basalt, Rheinisches Schiefergebirge, Germany.

    Science.gov (United States)

    Peckmann, J; Bach, W; Behrens, K; Reitner, J

    2008-03-01

    Middle Devonian (Givetian) pillow basalt and inter-pillow breccia from the Rheinisches Schiefergebirge in Germany were found to contain putative biogenic filaments that indicate that life once proliferated within these volcanic rocks. Mineralized filaments are found in carbonate amygdules (vesicles filled by carbonate cement) in the volcanic rock, where they started to form on the internal surface of the once water-filled vesicles. Biogenicity of the filaments is indicated by (1) their size and shape resembling modern microorganisms including a constant diameter along the length of curved filaments, (2) their independence of crystal faces or cleavage planes, (3) branching patterns reminiscent of modern microorganisms, and (4) their spatial clustering and preferential occurrence close to the margin of pillows and in the inter-pillow breccias. A time lag between the deposition of pillow basalt and the activity of endoliths is revealed by the sequence of carbonate cements filling the amygdules. The putative filamentous microorganisms thrived after the formation of early fibrous rim cement, but before later equant calcite spar filled most of the remaining porosity. Microbial clay authigenesis analogous to the encrustation of prokaryotes in modern iron-rich environments led to the preservation of filaments. The filaments predominantly consist of the clay minerals chamosite and illite. Having dwelled in water-filled vesicles, the Devonian basalt-hosted filaments apparently represent cryptoendoliths. This finding suggests that a previously unrecognized niche for life exists within volcanic rock.

  2. SCALE/MAVRIC calculation of dose rates measured for a gamma radiation source in a thick-walled transport and storage cask of ductile cast iron with lead inserts

    Science.gov (United States)

    Baumgarten, Werner; Thiele, Holger; Ruprecht, Benjamin; Phlippen, Peter-W.; Schlömer, Luc

    2017-09-01

    Dose rate calculations are important for judging the shielding performance of transport casks for radioactive material. Therefore it is important to have reliable calculation tools. We report on measured and calculated dose rates near a thick-walled transport and storage cask of ductile cast iron with lead inserts and a Co-60 source inside. In a series of experiments the thickness of the inserts was varied, and measured dose rates near the cask were compared with SCALE/MAVRIC 6.1.3 and SCALE/MAVRIC 6.2 calculation results. Deviations from the measurements were found to be higher for increased lead thicknesses. Furthermore, it is shown how the shielding material density, air scattering and accounting for the floor influence the quality of the calculation.

  3. Iron load

    Directory of Open Access Journals (Sweden)

    Filippo Cassarà

    2013-03-01

    Full Text Available Recent research addressed the main role of hepcidin in the regulation of iron metabolism. However, while this mechanism could be relevant in causing iron load in Thalassemia Intermedia and Sickle-Cell Anemia, its role in Thalassemia Major (TM is marginal. This is mainly due to the high impact of transfusional requirement into the severe increase of body iron. Moreover, the damage of iron load may be worsened by infections, as HCV hepatitis, or liver and endocrinological damage. One of the most relevant associations was found between splenectomy and increase of risk for mortality due,probably, to more severe iron load. These issues suggest as morbidity and mortality of this group of patients they do not depend only by our ability in controlling heart damage but even in preventing or treating particular infections and complications. This finding is supported by the impairment of survival curves in patients with complications different from heart damage. However, because, during recent years different direct and indirect methods to detect iron overload in patients affected by secondary hemochromatosis have been implemented, our ability to maintain under control iron load is significantly improved. Anyway, the future in iron load management remains to be able to have an iron load map of our body for targeting chelation and other medical treatment according to the single organ damage.

  4. The ttpC gene is contained in two of three TonB systems in the human pathogen Vibrio vulnificus, but only one is active in iron transport and virulence.

    Science.gov (United States)

    Kustusch, Ryan J; Kuehl, Carole J; Crosa, Jorge H

    2012-06-01

    The TonB system of proteins is required for the energy-dependent active transport of iron-bound substrates across the outer membrane of gram-negative bacteria. We have identified three TonB systems within the human pathogen Vibrio vulnificus. The TonB1 system contains the TonB1, ExbD1, and ExbB1 proteins, whereas both the TtpC2-TonB2 and TtpC3-TonB3 systems contain an additional fourth protein, TtpC. Here we report that TtpC3, although highly related to TtpC2, is inactive in iron transport, whereas TtpC2 is essential for the function of the TtpC2-TonB2 system in V. vulnificus. This protein, together with TonB2, is absolutely required for both the uptake of endogenously produced iron-bound siderophores as well as siderophores produced from other organisms. Through complementation we show that V. vulnificus is capable of using different TtpC2 proteins from other Vibrio species to drive the uptake of multiple siderophores. We have also determined that aerobactin, a common bacterial siderophore involved in virulence of enteric bacteria, can only be brought into the cell using the TtpC2-TonB2 system, indicating an important evolutionary adaptation of TtpC2 and TonB2. Furthermore, in the absence of TonB1, TtpC2 is essential for a fully virulent phenotype as demonstrated using 50% lethal dose (LD(50)) experiments in mice.

  5. 49 CFR 192.369 - Service lines: Connections to cast iron or ductile iron mains.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Service lines: Connections to cast iron or ductile...) PIPELINE SAFETY TRANSPORTATION OF NATURAL AND OTHER GAS BY PIPELINE: MINIMUM FEDERAL SAFETY STANDARDS Customer Meters, Service Regulators, and Service Lines § 192.369 Service lines: Connections to cast iron...

  6. The endocytic receptor megalin binds the iron transporting neutrophil-gelatinase-associated lipocalin with high affinity and mediates its cellular uptake

    DEFF Research Database (Denmark)

    Hvidberg, Vibeke; Jacobsen, Christian; Strong, Roland K

    2005-01-01

    in delivering iron to cells during formation of the tubular epithelial cells of the primordial kidney. No cellular receptor for NGAL has been described. We show here that megalin, a member of the low-density lipoprotein receptor family expressed in polarized epithelia, binds NGAL with high affinity, as shown...

  7. Iron: a pathological mediator of Alzheimer disease?

    Science.gov (United States)

    Bishop, Glenda M; Robinson, Stephen R; Liu, Quan; Perry, George; Atwood, Craig S; Smith, Mark A

    2002-01-01

    Brains from patients with Alzheimer disease (AD) show a disruption in the metabolism of iron, such that there is an accumulation of iron in senile plaques, and an altered distribution of iron transport and storage proteins. One of the earliest events in AD is the generation of oxidative stress, which may be related to the generation of free radicals by the excess iron that is observed in the disease. Iron has also been shown to mediate the in vitro toxicity of amyloid-beta peptide, and the presence of iron in most in vitro systems could underlie the toxicity that is normally attributed to amyloid-beta in these studies. In contrast, several recent studies have suggested that amyloid-beta may decrease oxidative stress and decrease the toxicity of iron. Continued examination of the complex interactions that occur between iron and amyloid-beta may assist in the elucidation of the mechanisms that underlie the neurodegeneration that leads to dementia in AD.

  8. Iron, hepcidin and the metal connection.

    Directory of Open Access Journals (Sweden)

    Olivier eLoréal

    2014-06-01

    Full Text Available Identification of new players in iron metabolism, such as hepcidin, which regulates ferroportin and divalent metal transporter 1 expression, has improved our knowledge of iron metabolism and iron-related diseases. However, from both experimental data and clinical findings, iron-related proteins appear to also be involved in the metabolism of other metals, especially divalent cations. Reports have demonstrated that some metals may affect, directly or indirectly, the expression of proteins involved in iron metabolism. Throughout their lives, individuals are exposed to various metals during personal and/or occupational activities. Therefore, better knowledge of the connections between iron and other metals could improve our understanding of iron-related diseases, especially the variability in phenotypic expression, as well as a variety of diseases in which iron metabolism is secondarily affected. Controlling the metabolism of other metals could represent a promising innovative therapeutic approach.

  9. Mechanistic and regulatory aspects of intestinal iron absorption

    OpenAIRE

    2014-01-01

    Iron is an essential trace mineral that plays a number of important physiological roles in humans, including oxygen transport, energy metabolism, and neurotransmitter synthesis. Iron absorption by the proximal small bowel is a critical checkpoint in the maintenance of whole-body iron levels since, unlike most other essential nutrients, no regulated excretory systems exist for iron in humans. Maintaining proper iron levels is critical to avoid the adverse physiological consequences of either l...

  10. Iron Deficiency in Heart Failure: A Practical Guide

    OpenAIRE

    Nicole Ebner; Stephan von Haehling

    2013-01-01

    Iron is an element necessary for cells due to its capacity of transporting oxygen and electrons. One of the important co-morbidities in heart failure is iron deficiency. Iron has relevant biological functions, for example, the formation of haemoglobin, myoglobin and numerous enzymatic groups. The prevalence of iron deficiency increases with the severity of heart failure. For a long time, the influence of iron deficiency was underestimated especially in terms of worsening of cardiovascular dis...

  11. Iron refractory iron deficiency anemia

    OpenAIRE

    De Falco, Luigia; Sanchez, Mayka; Silvestri, Laura; Kannengiesser, Caroline; Muckenthaler, Martina U; Iolascon, Achille; Gouya, Laurent; Camaschella, Clara; Beaumont, Carole

    2013-01-01

    Iron refractory iron deficiency anemia is a hereditary recessive anemia due to a defect in the TMPRSS6 gene encoding Matriptase-2. This protein is a transmembrane serine protease that plays an essential role in down-regulating hepcidin, the key regulator of iron homeostasis. Hallmarks of this disease are microcytic hypochromic anemia, low transferrin saturation and normal/high serum hepcidin values. The anemia appears in the post-natal period, although in some cases it is only diagnosed in ad...

  12. Iron regulatory proteins control a mucosal block to intestinal iron absorption.

    Science.gov (United States)

    Galy, Bruno; Ferring-Appel, Dunja; Becker, Christiane; Gretz, Norbert; Gröne, Hermann-Josef; Schümann, Klaus; Hentze, Matthias W

    2013-03-28

    Mammalian iron metabolism is regulated systemically by the hormone hepcidin and cellularly by iron regulatory proteins (IRPs) that orchestrate a posttranscriptional regulatory network. Through ligand-inducible genetic ablation of both IRPs in the gut epithelium of adult mice, we demonstrate that IRP deficiency impairs iron absorption and promotes mucosal iron retention via a ferritin-mediated "mucosal block." We show that IRP deficiency does not interfere with intestinal sensing of body iron loading and erythropoietic iron need, but rather alters the basal expression of the iron-absorption machinery. IRPs thus secure sufficient iron transport across absorptive enterocytes by restricting the ferritin "mucosal block" and define a basal set point for iron absorption upon which IRP-independent systemic regulatory inputs are overlaid.

  13. Iron Regulatory Proteins Control a Mucosal Block to Intestinal Iron Absorption

    Directory of Open Access Journals (Sweden)

    Bruno Galy

    2013-03-01

    Full Text Available Mammalian iron metabolism is regulated systemically by the hormone hepcidin and cellularly by iron regulatory proteins (IRPs that orchestrate a posttranscriptional regulatory network. Through ligand-inducible genetic ablation of both IRPs in the gut epithelium of adult mice, we demonstrate that IRP deficiency impairs iron absorption and promotes mucosal iron retention via a ferritin-mediated “mucosal block.” We show that IRP deficiency does not interfere with intestinal sensing of body iron loading and erythropoietic iron need, but rather alters the basal expression of the iron-absorption machinery. IRPs thus secure sufficient iron transport across absorptive enterocytes by restricting the ferritin “mucosal block” and define a basal set point for iron absorption upon which IRP-independent systemic regulatory inputs are overlaid.

  14. Cast irons

    CERN Document Server

    1996-01-01

    Cast iron offers the design engineer a low-cost, high-strength material that can be easily melted and poured into a wide variety of useful, and sometimes complex, shapes. This latest handbook from ASM covers the entire spectrum of one of the most widely used and versatile of all engineered materials. The reader will find the basic, but vital, information on metallurgy, solidification characteristics, and properties. Extensive reviews are presented on the low-alloy gray, ductile, compacted graphite, and malleable irons. New and expanded material has been added covering high-alloy white irons used for abrasion resistance and high-alloy graphitic irons for heat and corrosion resistance. Also discussed are melting furnaces and foundry practices such as melting, inoculation, alloying, pouring, gating and rising, and molding. Heat treating practices including stress relieving, annealing, normalizing, hardening and tempering, autempering (of ductile irons), and surface-hardening treatments are covered, too. ASM Spec...

  15. Iron acquisition and allocation in stramenopile algae.

    Science.gov (United States)

    Raven, John A

    2013-05-01

    The essential element iron has a low biological availability in the surface ocean where photosynthetic organisms live. Recent advances in our understanding of iron acquisition mechanisms in brown algae and diatoms (stramenopile algae) show the importance of the reduction of ferric to ferrous iron prior to, or during, transport in the uptake process. The uses of iron in photosynthetic stramenopiles resembles that in other oxygenic organisms, although (with the exception of the diatom Thalassiosira oceanica from an iron-deficient part of the ocean) they lack plastocyanin, instead using cytochrome c 6, This same diatom further economizes genotypically on the use of iron in photosynthesis by decreasing the expression of photosystem I, cytochrome c 6, and the cytochrome b 6 f complex per cell and per photosystem II relative to the coastal Thalassiosira pseudonana; similar changes occur phenotypically in response to iron deficiency in other diatoms such as Phaeodactylum tricornutum. In some diatoms grown under iron-limiting conditions, essentially all of the iron in the cells can be accounted for by the iron occurring in catalytic proteins. However, stramenopiles can store iron. Genomic studies show that pennate, but not centric, diatoms have the iron storage protein ferritin. While Mössbauer and X-ray analysis of (57)Fe-labelled Ectocarpus siliculosus shows iron in an amorphous mineral phase resembling the core of ferritin, the genome shows no protein with significant sequence similarity to ferritin.

  16. Iron utilization in marine cyanobacteria and eukaryotic algae

    Directory of Open Access Journals (Sweden)

    Joe eMorrissey

    2012-03-01

    Full Text Available Iron is essential for aerobic organisms. Additionally, photosynthetic organisms must maintain the iron-rich photosynthetic electron transport chain, which likely evolved in the iron-replete Proterozoic ocean. The subsequent rise in oxygen since those times has drastically decreased the levels of bioavailable iron, indicating that adaptations have been made to maintain sufficient cellular iron levels in the midst of scarcity. In combination with physiological studies, the recent sequencing of marine microorganism genomes and transcriptomes has begun to reveal the mechanisms of iron acquisition and utilization that allow marine microalgae to persist in iron-limited environments.

  17. Iron utilization in marine cyanobacteria and eukaryotic algae.

    Science.gov (United States)

    Morrissey, Joe; Bowler, Chris

    2012-01-01

    Iron is essential for aerobic organisms. Additionally, photosynthetic organisms must maintain the iron-rich photosynthetic electron transport chain, which likely evolved in the iron-replete Proterozoic ocean. The subsequent rise in oxygen since those times has drastically decreased the levels of bioavailable iron, indicating that adaptations have been made to maintain sufficient cellular iron levels in the midst of scarcity. In combination with physiological studies, the recent sequencing of marine microorganism genomes and transcriptomes has begun to reveal the mechanisms of iron acquisition and utilization that allow marine microalgae to persist in iron limited environments.

  18. Transport genes and chemotaxis in Laribacter hongkongensis: a genome-wide analysis

    Directory of Open Access Journals (Sweden)

    Lau Susanna KP

    2011-08-01

    Full Text Available Abstract Background Laribacter hongkongensis is a Gram-negative, sea gull-shaped rod associated with community-acquired gastroenteritis. The bacterium has been found in diverse freshwater environments including fish, frogs and drinking water reservoirs. Using the complete genome sequence data of L. hongkongensis, we performed a comprehensive analysis of putative transport-related genes and genes related to chemotaxis, motility and quorum sensing, which may help the bacterium adapt to the changing environments and combat harmful substances. Results A genome-wide analysis using Transport Classification Database TCDB, similarity and keyword searches revealed the presence of a large diversity of transporters (n = 457 and genes related to chemotaxis (n = 52 and flagellar biosynthesis (n = 40 in the L. hongkongensis genome. The transporters included those from all seven major transporter categories, which may allow the uptake of essential nutrients or ions, and extrusion of metabolic end products and hazardous substances. L. hongkongensis is unique among closely related members of Neisseriaceae family in possessing higher number of proteins related to transport of ammonium, urea and dicarboxylate, which may reflect the importance of nitrogen and dicarboxylate metabolism in this assacharolytic bacterium. Structural modeling of two C4-dicarboxylate transporters showed that they possessed similar structures to the determined structures of other DctP-TRAP transporters, with one having an unusual disulfide bond. Diverse mechanisms for iron transport, including hemin transporters for iron acquisition from host proteins, were also identified. In addition to the chemotaxis and flagella-related genes, the L. hongkongensis genome also contained two copies of qseB/qseC homologues of the AI-3 quorum sensing system. Conclusions The large number of diverse transporters and genes involved in chemotaxis, motility and quorum sensing suggested that the bacterium may

  19. A novel putative auxin carrier family regulates intracellular auxin homeostasis in plants

    OpenAIRE

    2012-01-01

    The phytohormone auxin acts as a prominent signal, providing, by its local accumulation or depletion in selected cells, a spatial and temporal reference for changes in the developmental program. The distribution of auxin depends on both auxin metabolism (biosynthesis, conjugation and degradation) and cellular auxin transport. We identified in silico a novel putative auxin transport facilitator family, called PIN-LIKES (PILS). Here we illustrate that PILS proteins are required for auxin-depend...

  20. Mechanisms of heme iron absorption: Current questions and controversies

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Iron is a critical micronutrient, and iron derived from heme contributes a large proportion of the total iron absorbed in a typical Western diet. Heine iron is absorbed by different mechanisms than non-heine iron, but despite considerable study over many years these mechanisms remain poorly understood. This review provides an overview of the importance of heme iron in the diet and discusses the two prevailing hypotheses of heine absorption; namely receptor mediated endocytosis of heme, and direct transport into the intestinal enterocyte by recently discovered heine transporters. A specific emphasis is placed on the questions surrounding the site of heme catabolism and the identity of the enzyme that performs this task. Additionally, we present the hypothesis that a nonheme iron transport protein may be required for heine iron absorption and discuss the experiences of our laboratory in examining this hypothesis.

  1. HtaA is an iron-regulated hemin binding protein involved in the utilization of heme iron in Corynebacterium diphtheriae.

    Science.gov (United States)

    Allen, Courtni E; Schmitt, Michael P

    2009-04-01

    Many human pathogens, including Corynebacterium diphtheriae, the causative agent of diphtheria, use host compounds such as heme and hemoglobin as essential iron sources. In this study, we examined the Corynebacterium hmu hemin transport region, a genetic cluster that contains the hmuTUV genes encoding a previously described ABC-type hemin transporter and three additional genes, which we have designated htaA, htaB, and htaC. The hmu gene cluster is composed of three distinct transcriptional units. The htaA gene appears to be part of an iron- and DtxR-regulated operon that includes hmuTUV, while htaB and htaC are transcribed from unique DtxR-regulated promoters. Nonpolar deletion of either htaA or the hmuTUV genes resulted in a reduced ability to use hemin as an iron source, while deletion of htaB had no effect on hemin iron utilization in C. diphtheriae. A comparison of the predicted amino acid sequences of HtaA and HtaB showed that they share some sequence similarity, and both proteins contain leader sequences and putative C-terminal transmembrane regions. Protein localization studies with C. diphtheriae showed that HtaA is associated predominantly with the cell envelope when the organism is grown in minimal medium but is secreted during growth in nutrient-rich broth. HtaB and HmuT were detected primarily in the cytoplasmic membrane fraction regardless of the growth medium. Hemin binding studies demonstrated that HtaA and HtaB are able to bind hemin, suggesting that these proteins may function as cell surface hemin receptors in C. diphtheriae.

  2. Speciation of the elements and compositions on the surfaces of dust storm particles: The evidence for the coupling of iron with sulfur in aerosol during the long-range transport

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xingying; ZHUANG Guoshun; CHEN Jianmin; XUE Huaxin

    2005-01-01

    The speciation of the elements on the surface of the particles collected during dust storm and non-dust storm in Beijing and Inner Mongolia was studied by XPS. The major species of iron on the surface were oxides, sulfate, silicate, FeOOH and minor part sorbed on SiO2/Al2O3. Sulfate is the dominant species of sulfur on the surface. SiO2 and Al2O3 are the main components of Si and Al on the surface respectively. One of the most important findings was that the Fe(II) (FeS and FeSO4) produced could account for up to 44.3% and 45.6% of the total Fe on the surface in the aerosol sample collected at that night and next day of the "peak" time of the dust storm occurring on March 20, 2002, while Fe2(SO4)3, one of the Fe(III) species on the surface decreased from 67.1% to 49.5% and 48.0% respectively. Both S and Fe enriched on the surface of aerosol particles. Fe(II) accounted for 1.3%-5.3% of total Fe in bulk aerosol samples during dust storm. These results provided strong evidence to support the hypothesis of the coupling between iron and sulfur in aerosols during the long-range transport, which would have important impact on the global biogeochemical cycle.

  3. A novel mode of ferric ion coordination by the periplasmic ferric ion-binding subunit FbpA of an ABC-type iron transporter from Thermus thermophilus HB8.

    Science.gov (United States)

    Wang, Shipeng; Ogata, Misaki; Horita, Shoichiro; Ohtsuka, Jun; Nagata, Koji; Tanokura, Masaru

    2014-01-01

    Crystal structures of FbpA, the periplasmic ferric ion-binding protein of an iron-uptake ABC transporter, from Thermus thermophilus HB8 (TtFbpA) have been solved in apo and ferric ion-bound forms at 1.8 and 1.7 Å resolution, respectively. The latter crystal structure shows that the bound ferric ion forms a novel six-coordinated complex with three tyrosine side chains, two bicarbonates and a water molecule in the metal-binding site. The results of gel-filtration chromatography and dynamic light scattering show that TtFbpA exists as a monomer in solution regardless of ferric ion binding and that TtFbpA adopts a more compact conformation in the ferric ion-bound state than in the apo state in solution.

  4. Ferritins and iron storage in plants.

    Science.gov (United States)

    Briat, Jean-François; Duc, Céline; Ravet, Karl; Gaymard, Frédéric

    2010-08-01

    Iron is essential for both plant productivity and nutritional quality. Improving plant iron content was attempted through genetic engineering of plants overexpressing ferritins. However, both the roles of these proteins in the plant physiology, and the mechanisms involved in the regulation of their expression are largely unknown. Although the structure of ferritins is highly conserved between plants and animals, their cellular localization differ. Furthermore, regulation of ferritin gene expression in response to iron excess occurs at the transcriptional level in plants, in contrast to animals which regulate ferritin expression at the translational level. In this review, our knowledge of the specific features of plant ferritins is presented, at the level of their (i) structure/function relationships, (ii) cellular localization, and (iii) synthesis regulation during development and in response to various environmental cues. A special emphasis is given to their function in plant physiology, in particular concerning their respective roles in iron storage and in protection against oxidative stress. Indeed, the use of reverse genetics in Arabidopsis recently enabled to produce various knock-out ferritin mutants, revealing strong links between these proteins and protection against oxidative stress. In contrast, their putative iron storage function to furnish iron during various development processes is unlikely to be essential. Ferritins, by buffering iron, exert a fine tuning of the quantity of metal required for metabolic purposes, and help plants to cope with adverse situations, the deleterious effects of which would be amplified if no system had evolved to take care of free reactive iron.

  5. METABOLISM OF IRON STORES

    OpenAIRE

    Saito, Hiroshi

    2014-01-01

    ABSTRACT Remarkable progress was recently achieved in the studies on molecular regulators of iron metabolism. Among the main regulators, storage iron, iron absorption, erythropoiesis and hepcidin interact in keeping iron homeostasis. Diseases with gene-mutations resulting in iron overload, iron deficiency, and local iron deposition have been introduced in relation to the regulators of storage iron metabolism. On the other hand, the research on storage iron metabolism has not advanced since th...

  6. Sedimentary particulate iron: the missing micronutrients ?

    Science.gov (United States)

    Beghoura, Houda; Gorgues, Thomas; Aumont, Olivier; Planquette, Hélène

    2017-04-01

    Iron is known to regulate the marine primary production and to impact the structure of ecosystems. Indeed, iron is the limiting nutrient for the phytoplankton growth over about 30% of the global ocean. However, the nature of the external sources of iron to the ocean and their quantification remain uncertain. Among these external sources, the sediment sources have been recently shown to be underestimated. Besides, since the operationally defined dissolved iron (which is the sum of truly dissolved and colloidal iron) was traditionally assumed to be the only form available to phytoplankton and bacteria, most studies have focused on the supply of dissolved iron to the ocean, the role of the particulate fraction of iron being largely ignored. This traditional view has been recently challenged, noticeably, by observational evidences. Indeed, in situ observations have shown that large amounts of particulate iron are being resuspended from continental margins to the open ocean thanks to fine grained particles' transport over long distances. A fraction of this particulate iron may dissolve and thereby fuel the phytoplankton growth. The magnitude of the sedimentary sources of particulate iron and the releasing processes affecting this iron phase are not yet well constrained or quantified. As a consequence, the role of sedimentary particulate iron in the biogeochemical cycles is still unclear despite its potentially major widespread importance. Here, we propose a modeling exercise to assess the first order impacts of this newly considered particulate sedimentary iron on global ocean biogeochemistry. We designed global experiments with a coupled dynamical-biogeochemical model (NEMO-PISCES). First, a control simulation that includes only a sediment source of iron in the dissolved phase has been run. Then, this control simulation is being compared with simulations, in which we include a sediment source of iron in both phases (dissolved as well as particulate). Those latter

  7. Iron Dextran Injection

    Science.gov (United States)

    ... allergic to iron dextran injection; any other iron injections such as ferric carboxymaltose (Injectafer), ferumoxytol (Feraheme), iron sucrose (Venofer), or sodium ferric gluconate (Ferrlecit);any other ...

  8. Recent advances in iron metabolism and related disorders.

    Science.gov (United States)

    Camaschella, Clara; Strati, Paolo

    2010-10-01

    Iron is essential for life, because it is indispensable for several biological reactions such as oxygen transport, DNA synthesis and cell proliferation, but is toxic if present in excess since it causes cellular damage through free radical formation. Either cellular or systemic iron regulation can be disrupted in disorders of iron metabolism. In the past few years, our understanding of iron metabolism and its regulation has dramatically changed. New disorders of iron metabolism have emerged and the role of iron has started to be recognized as a cofactor of other disorders. The study of genetic conditions such as hemochromatosis and iron-refractory-iron-deficiency anemia (IRIDA) has provided crucial insights into the molecular mechanisms controlling iron homeostasis. In the future, these advances may be exploited for a more effective treatment of both genetic and acquired iron disorders.

  9. Probing the putative active site of YjdL

    DEFF Research Database (Denmark)

    Jensen, Johanne Mørch; Ismat, Fouzia; Szakonyi, Gerda;

    2012-01-01

    YjdL from E. coli is an unusual proton-coupled oligopeptide transporter (POT). Unlike prototypical POTs, dipeptides are preferred over tripeptides, in particular dipeptides with a positively charged C-terminal residue. To further understand this difference in peptide specificity, the sequences...... of YjdL and YdgR, a prototypical E. coli POT, were compared in light of the crystal structure of a POT from Shewanella oneidensis. Several residues found in the putative active site were mutated and the activities of the mutated variants were assessed in terms of substrate uptake assays, and changes...... pocket that opens towards the extracellular space. The C-terminal side chain faces in the opposite direction into a sub pocket that faces the cytoplasm. These data indicated a stabilizing effect on a bulky N-terminal residue by an Ala281Phe variant and on the dipeptide backbone by Trp278...

  10. Putative archaeal viruses from the mesopelagic ocean.

    Science.gov (United States)

    Vik, Dean R; Roux, Simon; Brum, Jennifer R; Bolduc, Ben; Emerson, Joanne B; Padilla, Cory C; Stewart, Frank J; Sullivan, Matthew B

    2017-01-01

    Oceanic viruses that infect bacteria, or phages, are known to modulate host diversity, metabolisms, and biogeochemical cycling, while the viruses that infect marine Archaea remain understudied despite the critical ecosystem roles played by their hosts. Here we introduce "MArVD", for Metagenomic Archaeal Virus Detector, an annotation tool designed to identify putative archaeal virus contigs in metagenomic datasets. MArVD is made publicly available through the online iVirus analytical platform. Benchmarking analysis of MArVD showed it to be >99% accurate and 100% sensitive in identifying the 127 known archaeal viruses among the 12,499 viruses in the VirSorter curated dataset. Application of MArVD to 10 viral metagenomes from two depth profiles in the Eastern Tropical North Pacific (ETNP) oxygen minimum zone revealed 43 new putative archaeal virus genomes and large genome fragments ranging in size from 10 to 31 kb. Network-based classifications, which were consistent with marker gene phylogenies where available, suggested that these putative archaeal virus contigs represented six novel candidate genera. Ecological analyses, via fragment recruitment and ordination, revealed that the diversity and relative abundances of these putative archaeal viruses were correlated with oxygen concentration and temperature along two OMZ-spanning depth profiles, presumably due to structuring of the host Archaea community. Peak viral diversity and abundances were found in surface waters, where Thermoplasmata 16S rRNA genes are prevalent, suggesting these archaea as hosts in the surface habitats. Together these findings provide a baseline for identifying archaeal viruses in sequence datasets, and an initial picture of the ecology of such viruses in non-extreme environments.

  11. Geoarchaeota: a new candidate phylum in the Archaea from high-temperature acidic iron mats in Yellowstone National Park

    Energy Technology Data Exchange (ETDEWEB)

    Kozubal, Mark; Romine, Margaret F.; Jennings, Ryan; Jay, Z.; Tringe, Susannah G.; Rusch, Douglas B.; Beam, Jake; McCue, Lee Ann; Inskeep, William P.

    2013-03-01

    Geothermal systems in Yellowstone National Park (YNP) provide an outstanding opportunity to understand the origin and evolution of metabolic processes necessary for life in extreme environments including low pH, high temperature, low oxygen and elevated concentrations of reduced iron. Previous phylogenetic studies of acidic ferric iron mats from YNP have revealed considerable diversity of uncultivated and undescribed archaea. The goal of this study was to obtain replicate de novo genome assemblies for a dominant archaeal population inhabiting acidic iron oxide mats in YNP. Detailed analysis of conserved ribosomal and informational processing genes indicate that the replicate assemblies represent a new phylum-level lineage referred to here as 'novel archaeal group 1 (NAG1)'. The NAG1 organisms contain pathways necessary for the catabolism of peptides and complex carbohydrates as well as a bacterial-like Form I CO dehydrogenase complex likely used for energy conservation. Moreover, this novel population contains genes involved in metabolism of oxygen including a Type A heme copper oxidase, a bd-type terminal oxidase and a putative oxygen sensing protoglobin. NAG1 has a variety of unique bacterial-like cofactor biosynthesis and transport genes and a Type3-like CRISPR system. Discovery of NAG1 is critical to our understanding of microbial community structure and function in extant thermophilic iron mats of YNP, and will provide insight regarding the evolution of Archaea in early Earth environments that may have important analogues active in YNP today.

  12. Geoarchaeota: a new candidate phylum in the Archaea from high-temperature acidic iron mats in Yellowstone National Park.

    Science.gov (United States)

    Kozubal, Mark A; Romine, Margaret; Jennings, Ryan deM; Jay, Zack J; Tringe, Susannah G; Rusch, Doug B; Beam, Jacob P; McCue, Lee Ann; Inskeep, William P

    2013-03-01

    Geothermal systems in Yellowstone National Park (YNP) provide an outstanding opportunity to understand the origin and evolution of metabolic processes necessary for life in extreme environments including low pH, high temperature, low oxygen and elevated concentrations of reduced iron. Previous phylogenetic studies of acidic ferric iron mats from YNP have revealed considerable diversity of uncultivated and undescribed archaea. The goal of this study was to obtain replicate de novo genome assemblies for a dominant archaeal population inhabiting acidic iron-oxide mats in YNP. Detailed analysis of conserved ribosomal and informational processing genes indicates that the replicate assemblies represent a new candidate phylum within the domain Archaea referred to here as 'Geoarchaeota' or 'novel archaeal group 1 (NAG1)'. The NAG1 organisms contain pathways necessary for the catabolism of peptides and complex carbohydrates as well as a bacterial-like Form I carbon monoxide dehydrogenase complex likely used for energy conservation. Moreover, this novel population contains genes involved in the metabolism of oxygen including a Type A heme copper oxidase, a bd-type terminal oxidase and a putative oxygen-sensing protoglobin. NAG1 has a variety of unique bacterial-like cofactor biosynthesis and transport genes and a Type3-like CRISPR system. Discovery of NAG1 is critical to our understanding of microbial community structure and function in extant thermophilic iron-oxide mats of YNP, and will provide insight regarding the evolution of Archaea in early Earth environments that may have important analogs active in YNP today.

  13. Discovery of a Superhard Iron Tetraboride Superconductor

    Science.gov (United States)

    Gou, Huiyang; Dubrovinskaia, Natalia; Bykova, Elena; Tsirlin, Alexander A.; Kasinathan, Deepa; Schnelle, Walter; Richter, Asta; Merlini, Marco; Hanfland, Michael; Abakumov, Artem M.; Batuk, Dmitry; Van Tendeloo, Gustaaf; Nakajima, Yoichi; Kolmogorov, Aleksey N.; Dubrovinsky, Leonid

    2013-10-01

    Single crystals of novel orthorhombic (space group Pnnm) iron tetraboride FeB4 were synthesized at pressures above 8 GPa and high temperatures. Magnetic susceptibility and heat capacity measurements demonstrate bulk superconductivity below 2.9 K. The putative isotope effect on the superconducting critical temperature and the analysis of specific heat data indicate that the superconductivity in FeB4 is likely phonon mediated, which is rare for Fe-based superconductors. The discovered iron tetraboride is highly incompressible and has the nanoindentation hardness of 62(5) GPa; thus, it opens a new class of highly desirable materials combining advanced mechanical properties and superconductivity.

  14. Proteomic analysis of iron acquisition, metabolic and regulatory responses of Yersinia pestis to iron starvation

    Directory of Open Access Journals (Sweden)

    Fleischmann Robert D

    2010-01-01

    Full Text Available Abstract Background The Gram-negative bacterium Yersinia pestis is the causative agent of the bubonic plague. Efficient iron acquisition systems are critical to the ability of Y. pestis to infect, spread and grow in mammalian hosts, because iron is sequestered and is considered part of the innate host immune defence against invading pathogens. We used a proteomic approach to determine expression changes of iron uptake systems and intracellular consequences of iron deficiency in the Y. pestis strain KIM6+ at two physiologically relevant temperatures (26°C and 37°C. Results Differential protein display was performed for three Y. pestis subcellular fractions. Five characterized Y. pestis iron/siderophore acquisition systems (Ybt, Yfe, Yfu, Yiu and Hmu and a putative iron/chelate outer membrane receptor (Y0850 were increased in abundance in iron-starved cells. The iron-sulfur (Fe-S cluster assembly system Suf, adapted to oxidative stress and iron starvation in E. coli, was also more abundant, suggesting functional activity of Suf in Y. pestis under iron-limiting conditions. Metabolic and reactive oxygen-deactivating enzymes dependent on Fe-S clusters or other iron cofactors were decreased in abundance in iron-depleted cells. This data was consistent with lower activities of aconitase and catalase in iron-starved vs. iron-rich cells. In contrast, pyruvate oxidase B which metabolizes pyruvate via electron transfer to ubiquinone-8 for direct utilization in the respiratory chain was strongly increased in abundance and activity in iron-depleted cells. Conclusions Many protein abundance differences were indicative of the important regulatory role of the ferric uptake regulator Fur. Iron deficiency seems to result in a coordinated shift from iron-utilizing to iron-independent biochemical pathways in the cytoplasm of Y. pestis. With growth temperature as an additional variable in proteomic comparisons of the Y. pestis fractions (26°C and 37°C, there was

  15. Diurnal variation in the coupling of photosynthetic electron transport and carbon fixation in iron-limited phytoplankton in the NE subarctic Pacific

    Science.gov (United States)

    Schuback, Nina; Flecken, Mirkko; Maldonado, Maria T.; Tortell, Philippe D.

    2016-02-01

    Active chlorophyll a fluorescence approaches, including fast repetition rate fluorometry (FRRF), have the potential to provide estimates of phytoplankton primary productivity at an unprecedented spatial and temporal resolution. FRRF-derived productivity rates are based on estimates of charge separation in reaction center II (ETRRCII), which must be converted into ecologically relevant units of carbon fixation. Understanding sources of variability in the coupling of ETRRCII and carbon fixation provides physiological insight into phytoplankton photosynthesis and is critical for the application of FRRF as a primary productivity measurement tool. In the present study, we simultaneously measured phytoplankton carbon fixation and ETRRCII in the iron-limited NE subarctic Pacific over the course of a diurnal cycle. We show that rates of ETRRCII are closely tied to the diurnal cycle in light availability, whereas rates of carbon fixation appear to be influenced by endogenous changes in metabolic energy allocation under iron-limited conditions. Unsynchronized diurnal oscillations of the two rates led to 3.5-fold changes in the conversion factor between ETRRCII and carbon fixation (Kc / nPSII). Consequently, diurnal variability in phytoplankton carbon fixation cannot be adequately captured with FRRF approaches if a constant conversion factor is applied. Utilizing several auxiliary photophysiological measurements, we observed that a high conversion factor is associated with conditions of excess light and correlates with the increased expression of non-photochemical quenching (NPQ) in the pigment antenna, as derived from FRRF measurements. The observed correlation between NPQ and Kc / nPSII requires further validation but has the potential to improve estimates of phytoplankton carbon fixation rates from FRRF measurements alone.

  16. Iron Sucrose Injection

    Science.gov (United States)

    Iron sucrose injection is used treat iron-deficiency anemia (a lower than normal number of red blood cells due ... and may cause the kidneys to stop working). Iron sucrose injection is in a class of medications called iron ...

  17. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... enough iron, your body starts using the iron it has stored. Soon, the stored iron gets used ... fewer red blood cells. The red blood cells it does make have less hemoglobin than normal. Iron- ...

  18. Iron deficiency

    DEFF Research Database (Denmark)

    Schou, Morten; Bosselmann, Helle; Gaborit, Freja

    2015-01-01

    BACKGROUND: Both iron deficiency (ID) and cardiovascular biomarkers are associated with a poor outcome in heart failure (HF). The relationship between different cardiovascular biomarkers and ID is unknown, and the true prevalence of ID in an outpatient HF clinic is probably overlooked. OBJECTIVES.......043). CONCLUSION: ID is frequent in an outpatient HF clinic. ID is not associated with cardiovascular biomarkers after adjustment for traditional confounders. Inflammation, but not neurohormonal activation is associated with ID in systolic HF. Further studies are needed to understand iron metabolism in elderly HF...

  19. Iron acquisition and regulation systems in Streptococcus species.

    Science.gov (United States)

    Ge, Ruiguang; Sun, Xuesong

    2014-05-01

    Gram-positive Streptococcus species are responsible for millions of cases of meningitis, bacterial pneumonia, endocarditis, erysipelas and necrotizing fasciitis. Iron is essential for the growth and survival of Streptococcus in the host environment. Streptococcus species have developed various mechanisms to uptake iron from an environment with limited available iron. Streptococcus can directly extract iron from host iron-containing proteins such as ferritin, transferrin, lactoferrin and hemoproteins, or indirectly by relying on the employment of specialized secreted hemophores (heme chelators) and small siderophore molecules (high affinity ferric chelators). This review presents the most recent discoveries in the iron acquisition system of Streptococcus species - the transporters as well as the regulators.

  20. The Putative Role of the Non-Gastric H+/K+-ATPase ATP12A (ATP1AL1 as Anti-Apoptotic Ion Transporter: Effect of the H+/K+ ATPase Inhibitor SCH28080 on Butyrate-Stimulated Myelomonocytic HL-60 Cells

    Directory of Open Access Journals (Sweden)

    Martin Jakab

    2014-10-01

    Full Text Available Background/Aims: The ATP12A gene codes for a non-gastric H+/K+ ATPase, which is expressed in a wide variety of tissues. The aim of this study was to test for the molecular and functional expression of the non-gastric H+/K+ ATPase ATP12A/ATP1AL1 in unstimulated and butyrate-stimulated (1 and 10 mM human myelomonocytic HL-60 cells, to unravel its potential role as putative apoptosis-counteracting ion transporter as well as to test for the effect of the H+/K+ ATPase inhibitor SCH28080 in apoptosis. Methods: Real-time reverse-transcription PCR (qRT-PCR was used for amplification and cloning of ATP12A transcripts and to assess transcriptional regulation. BCECF microfluorimetry was used to assess changes of intracellular pH (pHi after acute intracellular acid load (NH4Cl prepulsing. Mean cell volumes (MCV and MCV-recovery after osmotic cell shrinkage (Regulatory Volume Increase, RVI were assessed by Coulter counting. Flow-cytometry was used to measure MCV (Coulter principle, to assess apoptosis (phosphatidylserine exposure to the outer leaflet of the cell membrane, caspase activity, 7AAD staining and differentiation (CD86 expression. Results: We found by RT-PCR, intracellular pH measurements, MCV measurements and flow cytometry that ATP12A is expressed in human myelomonocytic HL-60 cells. Treatment of HL-60 cells with 1 mM butyrate leads to monocyte-directed differentiation whereas higher concentrations (10 mM induce apoptosis as assessed by flow-cytometric determination of CD86 expression, caspase activity, phosphatidylserine exposure on the outer leaflet of the cell membrane and MCV measurements. Transcriptional up-regulation of ATP12A and CD86 is evident in 1 mM butyrate-treated HL-60 cells. The H+/K+ ATPase inhibitor SCH28080 (100 µM diminishes K+-dependent pHi recovery after intracellular acid load and blocks RVI after osmotic cell shrinkage. After seeding, HL-60 cells increase their MCV within the first 24 h in culture, and subsequently

  1. Southern Ocean Iron Experiment (SOFex)

    Energy Technology Data Exchange (ETDEWEB)

    Coale, Kenneth H.

    2005-07-28

    The Southern Ocean Iron Experiment (SOFeX) was an experiment decades in the planning. It's implementation was among the most complex ship operations that SIO has been involved in. The SOFeX field expedition was successful in creating and tracking two experimentally enriched areas of the Southern Ocean, one characterized by low silicic acid, one characterized by high silicic acid. Both experimental sites were replete with abundant nitrate. About 100 scientists were involved overall. The major findings of this study were significant in several ways: (1) The productivity of the southern ocean is limited by iron availability. (2) Carbon uptake and flux is therefore controlled by iron availability (3) In spite of low silicic acid, iron promotes non-silicious phytoplankton growth and the uptake of carbon dioxide. (4) The transport of fixed carbon from the surface layers proceeds with a C:N ratio that would indicate differential remineralization of nitrogen at shallow depths. (5) These finding have major implications for modeling of carbon export based on nitrate utilization. (6) The general results of the experiment indicate that, beyond other southern ocean enrichment experiments, iron inputs have a much wider impact of productivity and carbon cycling than previously demonstrated. Scientific presentations: Coale, K., Johnson, K, Buesseler, K., 2002. The SOFeX Group. Eos. Trans. AGU 83(47) OS11A-0199. Coale, K., Johnson, K. Buesseler, K., 2002. SOFeX: Southern Ocean Iron Experiments. Overview and Experimental Design. Eos. Trans. AGU 83 (47) OS22D-01. Buesseler, K.,et al. 2002. Does Iron Fertilization Enhance Carbon Sequestration? Particle flux results from the Southern Ocean Iron Experiment. Eos. Trans. AGU 83 (47), OS22D-09. Johnson, K. et al. 2002. Open Ocean Iron Fertilization Experiments From IronEx-I through SOFeX: What We Know and What We Still Need to Understand. Eos. Trans. AGU 83 (47), OS22D-12. Coale, K. H., 2003. Carbon and Nutrient Cycling During the

  2. Mitochondrial Iron-Sulfur Cluster Activity and Cytosolic Iron Regulate Iron Traffic in Saccharomyces cerevisiae*

    Science.gov (United States)

    Wofford, Joshua D.; Lindahl, Paul A.

    2015-01-01

    An ordinary differential equation-based mathematical model was developed to describe trafficking and regulation of iron in growing fermenting budding yeast. Accordingly, environmental iron enters the cytosol and moves into mitochondria and vacuoles. Dilution caused by increasing cell volume is included. Four sites are regulated, including those in which iron is imported into the cytosol, mitochondria, and vacuoles, and the site at which vacuolar FeII is oxidized to FeIII. The objective of this study was to determine whether cytosolic iron (Fecyt) and/or a putative sulfur-based product of iron-sulfur cluster (ISC) activity was/were being sensed in regulation. The model assumes that the matrix of healthy mitochondria is anaerobic, and that in ISC mutants, O2 diffuses into the matrix where it reacts with nonheme high spin FeII ions, oxidizing them to nanoparticles and generating reactive oxygen species. This reactivity causes a further decline in ISC/heme biosynthesis, which ultimately gives rise to the diseased state. The ordinary differential equations that define this model were numerically integrated, and concentrations of each component were plotted versus the concentration of iron in the growth medium and versus the rate of ISC/heme biosynthesis. Model parameters were optimized by fitting simulations to literature data. The model variant that assumed that both Fecyt and ISC biosynthesis activity were sensed in regulation mimicked observed behavior best. Such “dual sensing” probably arises in real cells because regulation involves assembly of an ISC on a cytosolic protein using Fecyt and a sulfur species generated in mitochondria during ISC biosynthesis and exported into the cytosol. PMID:26306041

  3. Computational modeling and analysis of iron release from macrophages.

    Directory of Open Access Journals (Sweden)

    Alka A Potdar

    2014-07-01

    Full Text Available A major process of iron homeostasis in whole-body iron metabolism is the release of iron from the macrophages of the reticuloendothelial system. Macrophages recognize and phagocytose senescent or damaged erythrocytes. Then, they process the heme iron, which is returned to the circulation for reutilization by red blood cell precursors during erythropoiesis. The amount of iron released, compared to the amount shunted for storage as ferritin, is greater during iron deficiency. A currently accepted model of iron release assumes a passive-gradient with free diffusion of intracellular labile iron (Fe2+ through ferroportin (FPN, the transporter on the plasma membrane. Outside the cell, a multi-copper ferroxidase, ceruloplasmin (Cp, oxidizes ferrous to ferric ion. Apo-transferrin (Tf, the primary carrier of soluble iron in the plasma, binds ferric ion to form mono-ferric and di-ferric transferrin. According to the passive-gradient model, the removal of ferrous ion from the site of release sustains the gradient that maintains the iron release. Subcellular localization of FPN, however, indicates that the role of FPN may be more complex. By experiments and mathematical modeling, we have investigated the detailed mechanism of iron release from macrophages focusing on the roles of the Cp, FPN and apo-Tf. The passive-gradient model is quantitatively analyzed using a mathematical model for the first time. A comparison of experimental data with model simulations shows that the passive-gradient model cannot explain macrophage iron release. However, a facilitated-transport model associated with FPN can explain the iron release mechanism. According to the facilitated-transport model, intracellular FPN carries labile iron to the macrophage membrane. Extracellular Cp accelerates the oxidation of ferrous ion bound to FPN. Apo-Tf in the extracellular environment binds to the oxidized ferrous ion, completing the release process. Facilitated-transport model can

  4. Transcriptional profiling of Actinobacillus pleuropneumoniae under iron-restricted conditions

    Directory of Open Access Journals (Sweden)

    Harel Josée

    2007-03-01

    Full Text Available Abstract Background To better understand effects of iron restriction on Actinobacillus pleuropneumoniae and to identify new potential vaccine targets, we conducted transcript profiling studies using a DNA microarray containing all 2025 ORFs of the genome of A. pleuropneumoniae serotype 5b strain L20. This is the first study involving the use of microarray technology to monitor the transcriptome of A. pleuropneumoniae grown under iron restriction. Results Upon comparing growth of this pathogen in iron-sufficient versus iron-depleted medium, 210 genes were identified as being differentially expressed. Some genes (92 were identified as being up-regulated; many have confirmed or putative roles in iron acquisition, such as the genes coding for two TonB energy-transducing proteins and the hemoglobin receptor HgbA. Transcript profiling also led to identification of some new iron acquisition systems of A. pleuropneumoniae. Genes coding for a possible Yfe system (yfeABCD, implicated in the acquisition of chelated iron, were detected, as well as genes coding for a putative enterobactin-type siderophore receptor system. ORFs for homologs of the HmbR system of Neisseria meningitidis involved in iron acquisition from hemoglobin were significantly up-regulated. Down-regulated genes included many that encode proteins containing Fe-S clusters or that use heme as a cofactor. Supplementation of the culture medium with exogenous iron re-established the expression level of these genes. Conclusion We have used transcriptional profiling to generate a list of genes showing differential expression during iron restriction. This strategy enabled us to gain a better understanding of the metabolic changes occurring in response to this stress. Many new potential iron acquisition systems were identified, and further studies will have to be conducted to establish their role during iron restriction.

  5. Iron biofortification and homeostasis in transgenic cassava roots expressing an algal iron assimilatory protein, FEA1

    Directory of Open Access Journals (Sweden)

    Uzoma eIhemere

    2012-09-01

    Full Text Available We have engineered the starchy root crop cassava (Manihot esculenta to express the Chlamydomonas reinhardtii iron assimilatory protein, FEA1, in roots to enhance its nutritional qualities. Iron levels in mature cassava storage roots were increased from 10 to 36 ppm in the highest iron accumulating transgenic lines. These iron levels are sufficient to meet the minimum daily requirement for iron in a 500 gm meal. Significantly, the expression of the FEA1 protein did not alter iron levels in leaves. Transgenic plants also had normal levels of zinc in leaves and roots consistent with the specific uptake of iron mediated by the FEA1 protein. Relative to wild-type plants, FEA1 expressing plants had reduced Fe(III chelate reductase activity and gene expression levels consistent with the more efficient uptake of iron in FEA1 transgenic plants. We also show that genes involved in iron homeostasis in cassava have altered tissue-specific patterns of expression in transgenic plants. Steady state transcript levels of the metal-chelate transporter MeYSL1, and the iron storage proteins, MeFER2 and MeFER6, were elevated in various tissues of FEA1 transgenic plants compared to wild-type plants. These results suggest that these gene products play a role in iron translocation and homeostasis in FEA1 transgenic cassava plants. These results are discussed in terms of enhanced strategies for the iron biofortification of plants.

  6. multicopper oxidases important for human iron metabolism

    Directory of Open Access Journals (Sweden)

    Diana Wierzbicka

    2014-01-01

    Full Text Available Multi-copper oxidases are a group of proteins which demonstrate enzymatic activity and are capable of oxidizing their substrates with the concomitant reduction of dioxygen to two water molecules. For some multi-copper oxidases there has been demonstrated ferroxidase activity which is related to their specific structure characterized by the presence of copper centres and iron-binding sites. Three multi-copper oxidases have been included in this group: ceruloplasmin, hephaestin and zyklopen. Multi copper oxidases which are expressed in different tissues are capable of oxidizing a wide spectrum of substrates. Multi-copper oxidases are capable of oxidizing a wide spectrum of substrates. Ceruloplasmin exhibits antioxidant activity as well as being involved in many other biological processes. The observations of phenotypic effects of absence or low expression of multi-copper ferroxidase-coding genes suggest that the main role of these proteins is taking part in iron metabolism. The main role of ceruloplasmin in iron turnover is oxidizing Fe2+ into Fe3+, a process which is essential for iron binding to transferrin (the main iron-transporting protein, as well as to ferritin (the main iron-storage protein. The function of hephaestin as ferroxidase is essential for iron binding to apotransferrin in the lamina propria of the intestinal mucosa, a process that is important for further transport of iron to the liver by the portal vein. Available data indicate that zyklopen is responsible for the placental iron transport. The presence of three multi-copper oxidases with ferroxidase activity emphasizes the significance of oxidation for iron metabolism. The distribution of multi-copper ferroxidases in many tissues ensures the proper iron turnover in the body as well as preventing toxic effects related to the presence of Fe2+ ions. These ions contribute to generation of free radicals, including the highly reactive hydroxyl radical, through the Fenton and Haber

  7. Iron and the female athlete: a review of dietary treatment methods for improving iron status and exercise performance

    OpenAIRE

    Alaunyte, Ieva; Stojceska, Valentina; Plunkett, Andrew

    2015-01-01

    Iron is a functional component of oxygen transport and energy production in humans and therefore is a critically important micronutrient for sport and exercise performance. Athletes, particularly female athletes participating in endurance sport, are at increased risk of compromised iron status due to heightened iron losses through menstruation and exercise-induced mechanisms associated with endurance activity. Conventionally oral iron supplementation is used in prevention or/and treatment of ...

  8. The iron-regulated staphylococcal lipoproteins

    Directory of Open Access Journals (Sweden)

    Jessica eSheldon

    2012-04-01

    Full Text Available Lipoproteins fulfill diverse roles in antibiotic resistance, adhesion, protein secretion, signaling and sensing, and many also serve as the substrate binding protein (SBP partner to ABC transporters for the acquisition of a diverse array of nutrients including peptides, sugars, and scarcely abundant metals. In the staphylococci, the iron-regulated SBPs are significantly upregulated during iron starvation and function to sequester and deliver iron into the bacterial cell, enabling staphylococci to circumvent iron restriction imposed by the host environment. Accordingly, this subset of lipoproteins has been implicated in staphylococcal pathogenesis and virulence. Lipoproteins also activate the host innate immune response, triggered through Toll-like receptor-2 (TLR2 and, notably, the iron-regulated subset of lipoproteins are particularly immunogenic. In this review, we discuss the iron-regulated staphylococcal lipoproteins with regard to their biogenesis, substrate specificity, and impact on the host innate immune response.

  9. Molecular mechanisms involved in intestinal iron absorption

    Institute of Scientific and Technical Information of China (English)

    Paul Sharp; Surjit Kaila Srai

    2007-01-01

    Iron is an essential trace metal in the human diet due to its obligate role in a number of metabolic processes.In the diet, iron is present in a number of different forms, generally described as haem (from haemoglobin and myoglobin in animal tissue) and non-haem iron (including ferric oxides and salts, ferritin and lactoferrin).This review describes the molecular mechanisms that co-ordinate the absorption of iron from the diet and its release into the circulation. While many components of the iron transport pathway have been elucidated, a number of key issues still remain to be resolved. Future work in this area will provide a clearer picture regarding the transcellular flux of iron and its regulation by dietary and humoral factors.

  10. Cellular distribution of ferric iron, ferritin, transferrin and divalent metal transporter 1 (DMT1) in substantia nigra and basal ganglia of normal and β2-microglobulin deficient mouse brain

    DEFF Research Database (Denmark)

    Moos, Torben; Trinder, D.; Morgan, E.H.

    2000-01-01

    beta-2-microglobulin, blood-brain barrier, gene knock out, iron, neurodegenerative disorders, oxidative damage, subthalamic nucleus......beta-2-microglobulin, blood-brain barrier, gene knock out, iron, neurodegenerative disorders, oxidative damage, subthalamic nucleus...

  11. Intestinal HIF2α promotes tissue-iron accumulation in disorders of iron overload with anemia.

    Science.gov (United States)

    Anderson, Erik R; Taylor, Matthew; Xue, Xiang; Ramakrishnan, Sadeesh K; Martin, Angelical; Xie, Liwei; Bredell, Bryce X; Gardenghi, Sara; Rivella, Stefano; Shah, Yatrik M

    2013-12-10

    Several distinct congenital disorders can lead to tissue-iron overload with anemia. Repeated blood transfusions are one of the major causes of iron overload in several of these disorders, including β-thalassemia major, which is characterized by a defective β-globin gene. In this state, hyperabsorption of iron is also observed and can significantly contribute to iron overload. In β-thalassemia intermedia, which does not require blood transfusion for survival, hyperabsorption of iron is the leading cause of iron overload. The mechanism of increased iron absorption in β-thalassemia is unclear. We definitively demonstrate, using genetic mouse models, that intestinal hypoxia-inducible factor-2α (HIF2α) and divalent metal transporter-1 (DMT1) are activated early in the pathogenesis of β-thalassemia and are essential for excess iron accumulation in mouse models of β-thalassemia. Moreover, thalassemic mice with established iron overload had significant improvement in tissue-iron levels and anemia following disruption of intestinal HIF2α. In addition to repeated blood transfusions and increased iron absorption, chronic hemolysis is the major cause of tissue-iron accumulation in anemic iron-overload disorders caused by hemolytic anemia. Mechanistic studies in a hemolytic anemia mouse model demonstrated that loss of intestinal HIF2α/DMT1 signaling led to decreased tissue-iron accumulation in the liver without worsening the anemia. These data demonstrate that dysregulation of intestinal hypoxia and HIF2α signaling is critical for progressive iron overload in β-thalassemia and may be a novel therapeutic target in several anemic iron-overload disorders.

  12. Effects of Pregnancy and Lactation on Iron Metabolism in Rats

    Directory of Open Access Journals (Sweden)

    Guofen Gao

    2015-01-01

    Full Text Available In female, inadequate iron supply is a highly prevalent problem that often leads to iron-deficiency anemia. This study aimed to understand the effects of pregnancy and lactation on iron metabolism. Rats with different days of gestation and lactation were used to determine the variations in iron stores and serum iron level and the changes in expression of iron metabolism-related proteins, including ferritin, ferroportin 1 (FPN1, ceruloplasmin (Cp, divalent metal transporter 1 (DMT1, transferrin receptor 1 (TfR1, and the major iron-regulatory molecule—hepcidin. We found that iron stores decline dramatically at late-pregnancy period, and the low iron store status persists throughout the lactation period. The significantly increased FPN1 level in small intestine facilitates digestive iron absorption, which maintains the serum iron concentration at a near-normal level to meet the increase of iron requirements. Moreover, a significant decrease of hepcidin expression is observed during late-pregnancy and early-lactation stages, suggesting the important regulatory role that hepcidin plays in iron metabolism during pregnancy and lactation. These results are fundamental to the understanding of iron homeostasis during pregnancy and lactation and may provide experimental bases for future studies to identify key molecules expressed during these special periods that regulate the expression of hepcidin, to eventually improve the iron-deficiency status.

  13. Ten Putative Contributors to the Obesity Epidemic

    Science.gov (United States)

    McAllister, Emily J.; Dhurandhar, Nikhil V.; Keith, Scott W.; Aronne, Louis J.; Barger, Jamie; Baskin, Monica; Benca, Ruth M.; Biggio, Joseph; Boggiano, Mary M.; Eisenmann, Joe C.; Elobeid, Mai; Fontaine, Kevin R.; Gluckman, Peter; Hanlon, Erin C.; Katzmarzyk, Peter; Pietrobelli, Angelo; Redden, David T.; Ruden, Douglas M.; Wang, Chenxi; Waterland, Robert A.; Wright, Suzanne M.; Allison, David B.

    2010-01-01

    The obesity epidemic is a global issue and shows no signs of abating, while the cause of this epidemic remains unclear. Marketing practices of energy-dense foods and institutionally-driven declines in physical activity are the alleged perpetrators for the epidemic, despite a lack of solid evidence to demonstrate their causal role. While both may contribute to obesity, we call attention to their unquestioned dominance in program funding and public efforts to reduce obesity, and propose several alternative putative contributors that would benefit from equal consideration and attention. Evidence for microorganisms, epigenetics, increasing maternal age, greater fecundity among people with higher adiposity, assortative mating, sleep debt, endocrine disruptors, pharmaceutical iatrogenesis, reduction in variability of ambient temperatures, and intrauterine and intergenerational effects, as contributing factors to the obesity epidemic are reviewed herein. While the evidence is strong for some contributors such as pharmaceutical-induced weight gain, it is still emerging for other reviewed factors. Considering the role of such putative etiological factors of obesity may lead to comprehensive, cause specific, and effective strategies for prevention and treatment of this global epidemic. PMID:19960394

  14. Identification of a DtxR-regulated operon that is essential for siderophore-dependent iron uptake in Corynebacterium diphtheriae.

    Science.gov (United States)

    Qian, Yilei; Lee, John H; Holmes, Randall K

    2002-09-01

    The diphtheria toxin repressor (DtxR) uses Fe(2+) as a corepressor and inhibits transcription from iron-regulated promoters (IRPs) in Corynebacterium diphtheriae. A new IRP, designated IRP6, was cloned from C. diphtheriae by a SELEX-like procedure. DtxR bound to IRP6 in vitro only in the presence of appropriate divalent metal ions, and repression of IRP6 by DtxR in an Escherichia coli system was iron dependent. The open reading frames (ORFs) downstream from IRP6 and previously described promoter IRP1 were found to encode proteins homologous to components of ATP-binding cassette (ABC) transport systems involved in high-affinity iron uptake in other bacteria. IRP1 and IRP6 were repressed under high-iron conditions in wild-type C. diphtheriae C7(beta), but they were expressed constitutively in C7(beta) mutant strains HC1, HC3, HC4, and HC5, which were shown previously to be defective in corynebactin-dependent iron uptake. A clone of the wild-type irp6 operon (pCM6ABC) complemented the constitutive corynebactin production phenotype of HC1, HC4, and HC5 but not of HC3, whereas a clone of the wild-type irp1 operon failed to complement any of these strains. Complementation by subclones of pCM6ABC demonstrated that mutant alleles of irp6A, irp6C, and irp6B were responsible for the phenotypes of HC1, HC4, and HC5, respectively. The irp6A allele in HC1 and the irp6B allele in HC5 encoded single amino acid substitutions in their predicted protein products, and the irp6C allele in HC4 caused premature chain termination of its predicted protein product. Strain HC3 was found to have a chain-terminating mutation in dtxR in addition to a missense mutation in its irp6B allele. These findings demonstrated that the irp6 operon in C. diphtheriae encodes a putative ABC transporter, that specific mutant alleles of irp6A, irp6B, and irp6C are associated with defects in corynebactin-dependent iron uptake, and that complementation of these mutant alleles restores repression of corynebactin

  15. Iron metabolism in BeWo chorion carcinoma cells. Transferrin-mediated uptake and release of iron.

    Science.gov (United States)

    van der Ende, A; du Maine, A; Simmons, C F; Schwartz, A L; Strous, G J

    1987-06-25

    Growing human choriocarcinoma BeWo b24 cells contain 1.5 X 10(6) functional cell surface transferrin binding sites and 2.0 X 10(6) intracellular binding sites. These cells rapidly accumulate iron at a rate of 360,000 iron atoms/min/cell. During iron uptake the transferrin and its receptor recycle at least each 19 min. The accumulated iron is released from the BeWo cells at a considerable rate. The time required to release 50% of previously accumulated iron into the extracellular medium is 30 h. This release process is cell line-specific as HeLa cells release very little if any iron. The release of iron by BeWo cells is stimulated by exogenous chelators such as apotransferrin, diethylenetriaminepenta-acetic acid, desferral, and apolactoferrin. The time required to release 50% of the previously accumulated iron into medium supplemented with chelator is 15 h. In the absence of added chelators iron is released as a low molecular weight complex, whereas in the presence of chelator the iron is found complexed to the chelator. Uptake of iron is inhibited by 250 microM primaquine or 2.5 microM monensin. However, the release of iron is not inhibited by these drugs. Intracellular iron is stored bound to ferritin. A model for the release of iron by BeWo cells and its implication for transplacental iron transport is discussed.

  16. Electric transport of a single-crystal iron chalcogenide FeSe superconductor: Evidence of symmetry-breakdown nematicity and additional ultrafast Dirac cone-like carriers

    Science.gov (United States)

    Huynh, K. K.; Tanabe, Y.; Urata, T.; Oguro, H.; Heguri, S.; Watanabe, K.; Tanigaki, K.

    2014-10-01

    An SDW antiferromagnetic (SDW-AF) low-temperature phase transition is generally observed and the AF spin fluctuations are considered to play an important role for the superconductivity pairing mechanism in FeAs superconductors. However, a similar magnetic phase transition is not observed in FeSe superconductors, which has caused considerable discussion. We report on the intrinsic electronic states of FeSe as elucidated by electric transport measurements under magnetic fields using a high quality single crystal. A mobility spectrum analysis, an ab initio method that does not make assumptions on the transport parameters in a multicarrier system, provides very important and clear evidence that another hidden order, most likely the symmetry broken from the tetragonal C4 symmetry to the C2 symmetry nematicity associated with the selective d -orbital splitting, exists in the case of superconducting FeSe other than the AF magnetic order spin fluctuations. The intrinsic low-temperature phase in FeSe is in the almost compensated semimetallic states but is additionally accompanied by Dirac cone-like ultrafast electrons ˜104cm2(VS) -1 as minority carriers.

  17. Iron bioavailability from commercially available iron supplements

    OpenAIRE

    2015-01-01

    Purpose Iron deficiency anaemia (IDA) is a global public health problem. Treatment with the standard of care ferrous iron salts may be poorly tolerated, leading to non-compliance and ineffective correction of IDA. Employing supplements with higher bioavailability might permit lower doses of iron to be used with fewer side effects, thus improving treatment efficacy. Here, we compared the iron bioavailability of ferrous sulphate tablets with alternative commercial iron products, including th...

  18. A study on species transport in the corrosion products of ferrous archaeological analogues - a contribution to the modelling of iron long term corrosion behaviour

    Energy Technology Data Exchange (ETDEWEB)

    Vega, E.; Dillmann, Ph.; Fluzin, Ph. [LRC CEA DSM 01-27: IRAMAT UMR5060 CNRS et Laboratoire Pierre Sue (CEA/CNRS), CEA Saclay 91191 Gif-sur-Yvette Cedex (France)

    2004-07-01

    One of the main technological and environmental challenges for the next centuries is the safe storage of nuclear wastes. For this purpose, the behaviour during several centuries of every material constituting the barrier between wastes and environment must be predicted. In addition to modelling and laboratory simulations, the only mean to study corrosion systems formed during several centuries is to analyse archaeological ferrous artefacts buried in soil. Precedent studies on this kind of artefacts have shown that the corrosion system is formed by the metallic core, a dense corrosion product layer, a transformed medium constituted of a mix of corrosion products and soil compounds, and the soil itself. Moreover, analytical and electrochemical studies seem to show that the corrosion mechanisms are driven by the species transport in the dense product layer (DPL) and especially by oxygen migration in the DPL pores. Thus, it seems necessary to precise the species transport properties in the DPL. A characterisation study on ferrous artefacts coming from the site of Glinet (16. AD) have been carried out. The rust layers have been studied using several techniques. The composition analyses were performed with Energy Dispersive Spectroscopy (EDS) coupled to the Scanning Electron Microscope, and Electron Probe Microanalysis (EPMA). Structural information have been obtained by X-ray micro-diffraction ({mu}XRD) and micro-Raman spectroscopy. The aim of this communication is to present the results of a study performed with markers in order to better understand the species transport in the DPL. Experiments focus on an archaeological artefact part from Glinet excavation. The migration in the DPL of I and Na ions (which have roughly the same diffusion coefficient in water than oxygen) will be studied by immersion of an archaeological analogue with his DPL in a saturated iodide (NaI) aqueous solution. After different immersion times (1 h, 3 h, 7 h and 168 h), the concentration

  19. Iron, phytoplankton growth, and the carbon cycle.

    Science.gov (United States)

    Street, Joseph H; Paytan, Adina

    2005-01-01

    Iron is an essential nutrient for all living organisms. Iron is required for the synthesis of chlorophyll and of several photosynthetic electron transport proteins and for the reduction of CO2, SO4(2-), and NO3(-) during the photosynthetic production of organic compounds. Iron concentrations in vast areas of the ocean are very low (iron in oxic seawater. Low iron concentrations have been shown to limit primary production rates, biomass accumulation, and ecosystem structure in a variety of open-ocean environments, including the equatorial Pacific, the subarctic Pacific and the Southern Ocean and even in some coastal areas. Oceanic primary production, the transfer of carbon dioxide into organic carbon by photosynthetic plankton (phytoplankton), is one process by which atmospheric CO2 can be transferred to the deep ocean and sequestered for long periods of time. Accordingly, iron limitation of primary producers likely plays a major role in the global carbon cycle. It has been suggested that variations in oceanic primary productivity, spurred by changes in the deposition of iron in atmospheric dust, control atmospheric CO2 concentrations, and hence global climate, over glacial-interglacial timescales. A contemporary application of this "iron hypothesis" promotes the large-scale iron fertilization of ocean regions as a means of enhancing the ability of the ocean to store anthropogenic CO2 and mitigate 21st century climate change. Recent in situ iron enrichment experiments in the HNLC regions, however, cast doubt on the efficacy and advisability of iron fertilization schemes. The experiments have confirmed the role of iron in regulating primary productivity, but resulted in only small carbon export fluxes to the depths necessary for long-term sequestration. Above all, these experiments and other studies of iron biogeochemistry over the last two decades have begun to illustrate the great complexity of the ocean system. Attempts to engineer this system are likely to

  20. Both immanently high active iron contents and increased root ferrous uptake in response to low iron stress contribute to the iron deficiency tolerance in Malus xiaojinensis.

    Science.gov (United States)

    Zha, Qian; Wang, Yi; Zhang, Xin-Zhong; Han, Zhen-Hai

    2014-01-01

    To better understand the mechanism of low-iron stress tolerance in Malus xiaojinensis, the differences in physiological parameters and gene expression between an iron deficiency-sensitive species, Malus baccata, and an iron deficiency-tolerant species, M. xiaojinensis were investigated under low-iron (4 μM Fe) conditions. Under iron sufficient conditions, the expressions of iron uptake- and transport-related genes, i.e. FIT1, IRT1, CS1, FRD3 and NRMAP1, and the immanent leaf and root active iron contents were higher in M. xiaojinensis than those in M. baccata. However, on the first three days of low iron stress, the rhizospheric pH decreased and the root ferric chelate reductase (FCR) activity and the expression of ferrous uptake- and iron transport-related genes in the roots increased significantly only in M. xiaojinensis. Leaf chlorosis occurred on the 3rd and the 9th day after low-iron treatment in M. baccata and M. xiaojinensis, respectively. The expression of iron relocalization-related genes, such as NAS1, FRD3 and NRMAP3, increased after the 5th or 6th day of low iron stress in leaves of M. xiaojinensis, whereas the expression of NAS1, FRD3 and NRMAP3 in the leaves of M. baccata increased immediately after the onset of low iron treatment. Conclusively, the relative high active iron contents caused by the immanently active root ferrous uptake and the increased root ferrous uptake in response to low iron stress were the dominant mechanisms for the tolerance to iron deficiency in M. xiaojinensis. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  1. Yap5 is an iron-responsive transcriptional activator that regulates vacuolar iron storage in yeast.

    Science.gov (United States)

    Li, Liangtao; Bagley, Dustin; Ward, Diane M; Kaplan, Jerry

    2008-02-01

    The transporter Ccc1 imports iron into the vacuole, which is the major site of iron storage in fungi and plants. CCC1 mRNA is destabilized under low-iron conditions by the binding of Cth1 and Cth2 to the 3' untranslated region (S. Puig, E. Askeland, and D. J. Thiele, Cell 120:99-110, 2005). Here, we show that the transcription of CCC1 is stimulated by iron through a Yap consensus site in the CCC1 promoter. We identified YAP5 as being the iron-sensitive transcription factor and show that a yap5Delta strain is sensitive to high iron. Green fluorescent protein-tagged Yap5 is localized to the nucleus and occupies the CCC1 promoter independent of the iron concentration. Yap5 contains two cysteine-rich domains, and the mutation of the cysteines to alanines in each of the domains affects the transcription of CCC1 but not DNA binding. The fusion of the Yap5 cysteine-containing domains to a GAL4 DNA binding domain results in iron-sensitive GAL1-lacZ expression. Iron affects the sulfhydryl status of Yap5, which is indicative of the generation of intramolecular disulfide bonds. These results show that Yap5 is an iron-sensing transcription factor and that iron regulates transcriptional activation.

  2. Yap5 Is an Iron-Responsive Transcriptional Activator That Regulates Vacuolar Iron Storage in Yeast▿

    Science.gov (United States)

    Li, Liangtao; Bagley, Dustin; Ward, Diane M.; Kaplan, Jerry

    2008-01-01

    The transporter Ccc1 imports iron into the vacuole, which is the major site of iron storage in fungi and plants. CCC1 mRNA is destabilized under low-iron conditions by the binding of Cth1 and Cth2 to the 3′ untranslated region (S. Puig, E. Askeland, and D. J. Thiele, Cell 120:99-110, 2005). Here, we show that the transcription of CCC1 is stimulated by iron through a Yap consensus site in the CCC1 promoter. We identified YAP5 as being the iron-sensitive transcription factor and show that a yap5Δ strain is sensitive to high iron. Green fluorescent protein-tagged Yap5 is localized to the nucleus and occupies the CCC1 promoter independent of the iron concentration. Yap5 contains two cysteine-rich domains, and the mutation of the cysteines to alanines in each of the domains affects the transcription of CCC1 but not DNA binding. The fusion of the Yap5 cysteine-containing domains to a GAL4 DNA binding domain results in iron-sensitive GAL1-lacZ expression. Iron affects the sulfhydryl status of Yap5, which is indicative of the generation of intramolecular disulfide bonds. These results show that Yap5 is an iron-sensing transcription factor and that iron regulates transcriptional activation. PMID:18070921

  3. A high-fidelity multiphysics model for the new solid oxide iron-air redox battery part I: Bridging mass transport and charge transfer with redox cycle kinetics

    Energy Technology Data Exchange (ETDEWEB)

    Jin, XF; Zhao, X; Huang, K

    2015-04-15

    A high-fidelity two-dimensional axial symmetrical multi-physics model is described in this paper as an effort to simulate the cycle performance of a recently discovered solid oxide metal-air redox battery (SOMARB). The model collectively considers mass transport, charge transfer and chemical redox cycle kinetics occurring across the components of the battery, and is validated by experimental data obtained from independent research. In particular, the redox kinetics at the energy storage unit is well represented by Johnson-Mehl-Avrami-Kolmogorov (JIVIAK) and Shrinking Core models. The results explicitly show that the reduction of Fe3O4 during the charging cycle limits the overall performance. Distributions of electrode potential, overpotential, Nernst potential, and H-2/H2O-concentration across various components of the battery are also systematically investigated. (C) 2015 Elsevier B.V. All rights reserved.

  4. Sorption of PAHs to humic acid- and iron(III)carbon ate particles by using passive dosing vials for investigating the transport of organic contamination in stormwater runoff

    DEFF Research Database (Denmark)

    Nielsen, Katrine; Mikkelsen, Peter Steen; Baun, Anders

    2013-01-01

    During the last decades, the growing urbanisation a nd increasing anthropogenic activities in urban areas have turned urban stormwater runoff int o a surface water quality contamination problem. The concerns of urban stormwater runoff as a source of contamination in the receiving surface water...... (lakes, rivers or sea) have been raised by researchers throughout the world (e.g. Broman et. al., 1987, and Xanthopoulos et. al., 1990), and have in Europe gained increased interest in relation to the implementatio n of the Water Framework Directive (WFD, 2000/60/EC). Particles (often defined as >0.45 μm......) has been foun d to facilitate transport of organic contaminants and metals in stormwater runoff system s, but little is known about the role of the colloidal fraction including nano-sized particl es (0.001-1 μm). Based on the large specific surface area of colloids and nanosized particles, t heir...

  5. High-rate behaviour of iron ore pellet

    Directory of Open Access Journals (Sweden)

    Gustafsson Gustaf

    2015-01-01

    Full Text Available Iron ore pellets are sintered, centimetre-sized spheres of ore with high iron content. Together with carbonized coal, iron ore pellets are used in the production of steel. In the transportation from the pelletizing plants to the customers, the iron ore pellets are exposed to different loading situations, resulting in degradation of strength and in some cases fragmentation. For future reliable numerical simulations of the handling and transportation of iron ore pellets, knowledge about their mechanical properties is needed. This paper describes the experimental work to investigate the dynamic mechanical properties of blast furnace iron ore pellets. To study the dynamic fracture of iron ore pellets a number of split Hopkinson pressure bar tests are carried out and analysed.

  6. Putative Nitrogen Sensing Systems in Higher Plants

    Institute of Scientific and Technical Information of China (English)

    Hon-Ming Lam; Ying Ann Chiao; Man-Wah Li; Yuk-Kwong Yung; Sang Ji

    2006-01-01

    Nitrogen (N) metabolism is essential for the biosynthesis of vital biomolecules. N status thus exerts profound effects on plant growth and development, and must be closely monitored. In bacteria and fungi, a few sophisticated N sensing systems have been extensively studied. In animals, the ability to receive amino acid signals has evolved to become an integral part of the nervous coordination system. In this review, we will summarize recent developments in the search for putative N sensing systems in higher plants based on homologous systems in bacteria, fungi, and animals. Apparently, although plants have separated and diversified from other organisms during the evolution process, striking similarities can be found in their N sensing systems compared with those of their counterparts; however, our understanding of these systems is still incomplete. Significant modifications of the N sensing systems (including cross-talk with other signal transduction pathways) in higher plants may be a strategy of adaptation to their unique mode of life.

  7. Putative respiratory chain of Porphyromonas gingivalis.

    Science.gov (United States)

    Meuric, Vincent; Rouillon, Astrid; Chandad, Fatiha; Bonnaure-Mallet, Martine

    2010-05-01

    The electron transfer chain in Porphyromonas gingivalis, or periodontopathogens, has not yet been characterized. P. gingivalis, a strict anaerobic bacteria and the second colonizer of the oral cavity, is considered to be a major causal agent involved in periodontal diseases. Primary colonizers create a favorable environment for P. gingivalis growth by decreasing oxygen pressure. Oxygen does not appear to be the final electron acceptor of the respiratory chain. Fumarate and cytochrome b have been implicated as major components of the respiratory activity. However, the P. gingivalis genome shows many other enzymes that could be implicated in aerobic or nitrite respiration. Using bioinformatic tools and literature studies of respiratory pathways, the ATP synthesis mechanism from the sodium cycle and nutrients metabolism, the putative respirasome of P. gingivalis has been proposed.

  8. Transdermal iron replenishment therapy.

    Science.gov (United States)

    Modepalli, Naresh; Shivakumar, H N; Kanni, K L Paranjothy; Murthy, S Narasimha

    2015-01-01

    Iron deficiency anemia is one of the major nutritional deficiency disorders. Iron deficiency anemia occurs due to decreased absorption of iron from diet, chronic blood loss and other associated diseases. The importance of iron and deleterious effects of iron deficiency anemia are discussed briefly in this review followed by the transdermal approaches to deliver iron. Transdermal delivery of iron would be able to overcome the side effects associated with conventional oral and parenteral iron therapy and improves the patient compliance. During preliminary investigations, ferric pyrophosphate and iron dextran were selected as iron sources for transdermal delivery. Different biophysical techniques were explored to assess their efficiency in delivering iron across the skin, and in vivo studies were carried out using anemic rat model. Transdermal iron delivery is a promising approach that could make a huge positive impact on patients suffering with iron deficiency.

  9. Nicotianamine synthase overexpression positively modulates iron homeostasis-related genes in high iron rice

    Directory of Open Access Journals (Sweden)

    Meng eWang

    2013-05-01

    Full Text Available Nearly one-third of the world population, mostly women and children, suffer from iron malnutrition and its consequences, such as anemia or impaired mental development. Biofortification of rice, which is a staple crop for nearly half of the world’s population, can significantly contribute in alleviating iron deficiency. NFP rice (transgenic rice expressing nicotianamine synthase, ferritin and phytase genes has a more than six-fold increase in iron content in polished rice grains, resulting from the synergistic action of nicotianamine synthase (NAS and ferritin transgenes. We investigated iron homeostasis in NFP plants by analyzing the expression of 28 endogenous rice genes known to be involved in the homeostasis of iron and other metals, in iron-deficient and iron-sufficient conditions. RNA was collected from different tissues (roots, flag leaves, grains and at three developmental stages during grain filling. NFP plants showed increased sensitivity to iron-deficiency conditions and changes in the expression of endogenous genes involved in nicotianamine (NA metabolism, in comparison to their non-transgenic siblings. Elevated transcript levels were detected in NFP plants for several iron transporters. In contrast, expression of OsYSL2, which encodes a member of Yellow Stripe-like protein family, and a transporter of the NA-Fe(II complex was reduced in NFP plants under low iron conditions, indicating that expression of OsYSL2 is regulated by the endogenous iron status. Expression of the transgenes did not significantly affect overall iron homeostasis in NFP plants, which establishes the engineered push-pull mechanism as a suitable strategy to increase rice endosperm iron content.

  10. Nicotianamine synthase overexpression positively modulates iron homeostasis-related genes in high iron rice.

    Science.gov (United States)

    Wang, Meng; Gruissem, Wilhelm; Bhullar, Navreet K

    2013-01-01

    Nearly one-third of the world population, mostly women and children, suffer from iron malnutrition and its consequences, such as anemia or impaired mental development. Biofortification of rice, which is a staple crop for nearly half of the world's population, can significantly contribute in alleviating iron deficiency. NFP rice (transgenic rice expressing nicotianamine synthase, ferritin and phytase genes) has a more than six-fold increase in iron content in polished rice grains, resulting from the synergistic action of nicotianamine synthase (NAS) and ferritin transgenes. We investigated iron homeostasis in NFP plants by analyzing the expression of 28 endogenous rice genes known to be involved in the homeostasis of iron and other metals, in iron-deficient and iron-sufficient conditions. RNA was collected from different tissues (roots, flag leaves, grains) and at three developmental stages during grain filling. NFP plants showed increased sensitivity to iron-deficiency conditions and changes in the expression of endogenous genes involved in nicotianamine (NA) metabolism, in comparison to their non-transgenic siblings (NTS). Elevated transcript levels were detected in NFP plants for several iron transporters. In contrast, expression of OsYSL2, which encodes a member of yellow stripe like protein family, and a transporter of the NA-Fe(II) complex was reduced in NFP plants under low iron conditions, indicating that expression of OsYSL2 is regulated by the endogenous iron status. Expression of the transgenes did not significantly affect overall iron homeostasis in NFP plants, which establishes the engineered push-pull mechanism as a suitable strategy to increase rice endosperm iron content.

  11. Vibrio cholerae VciB Mediates Iron Reduction.

    Science.gov (United States)

    Peng, Eric D; Payne, Shelley M

    2017-06-15

    Vibrio cholerae is the causative agent of the severe diarrheal disease cholera. V. cholerae thrives within the human host, where it replicates to high numbers, but it also persists within the aquatic environments of ocean and brackish water. To survive within these nutritionally diverse environments, V. cholerae must encode the necessary tools to acquire the essential nutrient iron in all forms it may encounter. A prior study of systems involved in iron transport in V. cholerae revealed the existence of vciB, which, while unable to directly transport iron, stimulates the transport of iron through ferrous (Fe(2+)) iron transport systems. We demonstrate here a role for VciB in V. cholerae in which VciB stimulates the reduction of Fe(3+) to Fe(2+), which can be subsequently transported into the cell with the ferrous iron transporter Feo. Iron reduction is independent of functional iron transport but is associated with the electron transport chain. Comparative analysis of VciB orthologs suggests a similar role for other proteins in the VciB family. Our data indicate that VciB is a dimer located in the inner membrane with three transmembrane segments and a large periplasmic loop. Directed mutagenesis of the protein reveals two highly conserved histidine residues required for function. Taken together, our results support a model whereby VciB reduces ferric iron using energy from the electron transport chain.IMPORTANCEVibrio cholerae is a prolific human pathogen and environmental organism. The acquisition of essential nutrients such as iron is critical for replication, and V. cholerae encodes a number of mechanisms to use iron from diverse environments. Here, we describe the V. cholerae protein VciB that increases the reduction of oxidized ferric iron (Fe(3+)) to the ferrous form (Fe(2+)), thus promoting iron acquisition through ferrous iron transporters. Analysis of VciB orthologs in Burkholderia and Aeromonas spp. suggest that they have a similar activity, allowing a

  12. Iron and iron derived radicals

    Energy Technology Data Exchange (ETDEWEB)

    Borg, D.C.; Schaich, K.M.

    1987-04-01

    We have discussed some reactions of iron and iron-derived oxygen radicals that may be important in the production or treatment of tissue injury. Our conclusions challenge, to some extent, the usual lines of thought in this field of research. Insofar as they are born out by subsequent developments, the lessons they teach are two: Think fastexclamation Think smallexclamation In other words, think of the many fast reactions that can rapidly alter the production and fate of highly reactive intermediates, and when considering the impact of competitive reactions on such species, think how they affect the microenvironment (on the molecular scale) ''seen'' by each reactive molecule. 21 refs., 3 figs., 1 tab.

  13. Analysis of novel iron-regulated, surface-anchored hemin-binding proteins in Corynebacterium diphtheriae.

    Science.gov (United States)

    Allen, Courtni E; Burgos, Jonathan M; Schmitt, Michael P

    2013-06-01

    Corynebacterium diphtheriae utilizes hemin and hemoglobin (Hb) as iron sources during growth in iron-depleted environments, and recent studies have shown that the surface-exposed HtaA protein binds both hemin and Hb and also contributes to the utilization of hemin iron. Conserved (CR) domains within HtaA and in the associated hemin-binding protein, HtaB, are required for the ability to bind hemin and Hb. In this study, we identified and characterized two novel genetic loci in C. diphtheriae that encode factors that bind hemin and Hb. Both genetic systems contain two-gene operons that are transcriptionally regulated by DtxR and iron. The gene products of these operons are ChtA-ChtB and ChtC-CirA (previously DIP0522-DIP0523). The chtA and chtB genes are carried on a putative composite transposon associated with C. diphtheriae isolates that dominated the diphtheria outbreak in the former Soviet Union in the 1990s. ChtA and ChtC each contain a single N-terminal CR domain and exhibit significant sequence similarity to each other but only limited similarity with HtaA. The chtB and htaB gene products exhibited a high level of sequence similarity throughout their sequences, and both proteins contain a single CR domain. Whole-cell binding studies as well as protease analysis indicated that all four of the proteins encoded by these two operons are surface exposed, which is consistent with the presence of a transmembrane segment in their C-terminal regions. ChtA, ChtB, and ChtC are able to bind hemin and Hb, with ChtA showing the highest affinity. Site-directed mutagenesis showed that specific tyrosine residues within the ChtA CR domain were critical for hemin and Hb binding. Hemin iron utilization assays using various C. diphtheriae mutants indicate that deletion of the chtA-chtB region and the chtC gene has no affect on the ability of C. diphtheriae to use hemin or Hb as iron sources; however, a chtB htaB double mutant exhibits a significant decrease in hemin iron use

  14. Iron and the female athlete: a review of dietary treatment methods for improving iron status and exercise performance.

    Science.gov (United States)

    Alaunyte, Ieva; Stojceska, Valentina; Plunkett, Andrew

    2015-01-01

    Iron is a functional component of oxygen transport and energy production in humans and therefore is a critically important micronutrient for sport and exercise performance. Athletes, particularly female athletes participating in endurance sport, are at increased risk of compromised iron status due to heightened iron losses through menstruation and exercise-induced mechanisms associated with endurance activity. Conventionally oral iron supplementation is used in prevention or/and treatment of iron deficiency. However, this approach has been criticised because of the side effects and increased risk of iron toxicity associated with the use of supplements. Thus, more recently there has been a growing interest in using dietary modification rather than the use of supplements to improve iron status of athletes. Dietary iron treatment methods include the prescription of an iron-rich diet, or/and haem iron-based diet, dietary advice counselling and inclusion of novel iron-rich products into the daily diet. Although studies using dietary modification are still scarce, current literature suggests that dietary iron interventions can assist in maintaining iron status in female athletes, especially during intensive training and competition. Future research should focus on the most efficient method(s) of dietary modification for improvement of iron status and whether these approaches can have a favourable impact on sports and exercise performance.

  15. Emergence of high-mobility minority holes in the electrical transport of the Ba (Fe1 -xMnxAs )2 iron pnictides

    Science.gov (United States)

    Urata, T.; Tanabe, Y.; Huynh, K. K.; Heguri, S.; Oguro, H.; Watanabe, K.; Tanigaki, K.

    2015-05-01

    In Fe pnictide (Pn) superconducting materials, neither Mn nor Cr doping to the Fe site induces superconductivity, even though hole carriers are generated. This is in strong contrast with the superconductivity appearing when holes are introduced by alkali-metal substitution on the insulating blocking layers. We investigate in detail the effects of Mn doping on magnetotransport properties in Ba (Fe1 -xMnxAs )2 for elucidating the intrinsic reason. The negative Hall coefficient for x =0 estimated in the low magnetic field (B ) regime gradually increases as x increases, and its sign changes to a positive one at x =0.020 . Hall resistivities as well as simultaneous interpretation using the magnetoconductivity tensor including both longitudinal and transverse transport components clarify that minority holes with high mobility are generated by the Mn doping via spin-density wave transition at low temperatures, while original majority electrons and holes residing in the paraboliclike Fermi surfaces of the semimetallic Ba (FeAs )2 are negligibly affected. Present results indicate that the mechanism of hole doping in Ba (Fe1 -xMnxAs )2 is greatly different from that of the other superconducting FePn family.

  16. Genetic/metabolic effect of iron metabolism and rare anemias

    Directory of Open Access Journals (Sweden)

    Clara Camaschella

    2013-03-01

    Full Text Available Advances in iron metabolism have allowed a novel classification of iron disorders and to identify previously unknown diseases. These disorders include genetic iron overload (hemochromatosis and inherited iron-related anemias, in some cases accompanied by iron overload. Rare inherited anemias may affect the hepcidin pathway, iron absorption, transport, utilization and recycling. Among the genetic iron-related anemias the most common form is likely the iron-refractory iron-deficiency anemia (IRIDA, due to mutations of the hepcidin inhibitor TMPRSS6 encoding the serine protease matriptase-2. IRIDA is characterized by hepcidin up-regulation, decrease iron absorption and macrophage recycling and by microcytic- hypochromic anemia, unresponsive to oral iron. High serum hepcidin levels may suggest the diagnosis, which requires demonstrating the causal TMPRSS6 mutations by gene sequencing. Other rare microcytic hypochromic anemias associated with defects of iron transport-uptake are the rare hypotransferrinemia, and DMT1 and STEAP3 mutations. The degree of anemia is variable and accompanied by secondary iron overload even in the absence of blood transfusions. This is due to the iron-deficient or expanded erythropoiesis that inhibits hepcidin transcription, increases iron absorption, through the erythroid regulator, as in untransfused beta-thalassemia. Sideroblastic anemias are due to decreased mitochondrial iron utilization for heme or sulfur cluster synthesis. Their diagnosis requires demonstrating ringed sideroblasts by Perl’s staining of the bone marrow smears. The commonest X-linked form is due to deltaamino- levulinic-synthase-2-acid (ALAS2 mutations. The recessive, more severe form, affects SLC25A38, which encodes a potential mitochondrial importer of glycine, an amino acid essential for ALA synthesis and thus results in heme deficiency. Two disorders affect iron/sulfur cluster biogenesis: deficiency of the ATP-binding cassette B7 (ABCB7 causes X

  17. Iron and stony-iron meteorites

    DEFF Research Database (Denmark)

    Benedix, Gretchen K.; Haack, Henning; McCoy, T. J.

    2014-01-01

    Without iron and stony-iron meteorites, our chances of ever sampling the deep interior of a differentiated planetary object would be next to nil. Although we live on a planet with a very substantial core, we will never be able to sample it. Fortunately, asteroid collisions provide us with a rich...... sampling of the deep interiors of differentiated asteroids. Iron and stony-iron meteorites are fragments of a large number of asteroids that underwent significant geological processing in the early solar system. Parent bodies of iron and some stony-iron meteorites completed a geological evolution similar...

  18. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... or an inability to absorb enough iron from food. Overview Iron-deficiency anemia is a common type ... of the condition. Treatments may include dietary changes, medicines, and surgery. Severe iron-deficiency anemia may require ...

  19. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... or an inability to absorb enough iron from food. Overview Iron-deficiency anemia is a common type ... condition. Treatments may include dietary changes, medicines, and surgery. Severe iron-deficiency anemia may require treatment in ...

  20. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... at highest risk for iron-deficiency anemia. Outlook Doctors usually can successfully treat iron-deficiency anemia. Treatment ... poor skin tone, dizziness, and depression. After her doctor diagnosed her with iron-deficiency anemia, Susan got ...

  1. Iron and Your Child

    Science.gov (United States)

    ... extra iron in their diets. People following a vegetarian diet might also need additional iron. What's Iron ... as Whole Milk? About Anemia Minerals What's a Vegetarian? Word! Anemia Anemia Food Labels Vitamins and Minerals ...

  2. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... Intramural Research Research Resources Research Meeting Summaries Technology Transfer Clinical Trials What Are Clinical Trials? Children & Clinical ... iron-deficiency anemia may require treatment in a hospital, blood transfusions , iron injections, or intravenous iron therapy. ...

  3. Complete Genome Sequence of the Filamentous Fungus Aspergillus westerdijkiae Reveals the Putative Biosynthetic Gene Cluster of Ochratoxin A

    Science.gov (United States)

    Chakrabortti, Alolika; Li, Jinming

    2016-01-01

    Ochratoxin A (OTA) is a common mycotoxin that contaminates food and agricultural products. Sequencing of the complete genome of Aspergillus westerdijkiae, a major producer of OTA, reveals more than 50 biosynthetic gene clusters, including a putative OTA biosynthetic gene cluster that encodes a dozen of enzymes, transporters, and regulatory proteins. PMID:27635003

  4. Structural, Transport and Electrochemical Properties of LiFePO4 Substituted in Lithium and Iron Sublattices (Al, Zr, W, Mn, Co and Ni

    Directory of Open Access Journals (Sweden)

    Konrad Świerczek

    2013-04-01

    Full Text Available LiFePO4 is considered to be one of the most promising cathode materials for lithium ion batteries for electric vehicle (EV application. However, there are still a number of unsolved issues regarding the influence of Li and Fe-site substitution on the physicochemical properties of LiFePO4. This is a review-type article, presenting results of our group, related to the possibility of the chemical modification of phosphoolivine by introduction of cation dopants in Li and Fe sublattices. Along with a synthetic review of previous papers, a large number of new results are included. The possibility of substitution of Li+ by Al3+, Zr4+, W6+ and its influence on the physicochemical properties of LiFePO4 was investigated by means of XRD, SEM/EDS, electrical conductivity and Seebeck coefficient measurements. The range of solid solution formation in Li1−3xAlxFePO4, Li1−4xZrxFePO4 and Li1−6xWxFePO4 materials was found to be very narrow. Transport properties of the synthesized materials were found to be rather weakly dependent on the chemical composition. The battery performance of selected olivines was tested by cyclic voltammetry (CV. In the case of LiFe1−yMyPO4 (M = Mn, Co and Ni, solid solution formation was observed over a large range of y (0 0.25 leads to considerably lower values of σ. The activated character of electrical conductivity with a rather weak temperature dependence of the Seebeck coefficient suggests a small polaron-type conduction mechanism. The electrochemical properties of LiFe1−yMyPO4 strongly depend on the Fe substitution level.

  5. Long-distance signaling of iron deficiency in plants

    OpenAIRE

    2008-01-01

    In a recent issue of the Planta, we established two points regarding the long-distance signal of iron status in tobacco (Nicotiana tabacum L.). One is that the long-distance signal generated in iron deficient tissues is a major factor in positively regulating the expressions of iron uptake genes in tobacco. The expression of a ferric chelate reductase gene (NtFRO1) and an iron-regulated transporter gene (NtIRT1) in roots decreased by cutting off the leaves grown under the iron-deficient condi...

  6. Targeting Iron Homeostasis in Acute Kidney Injury.

    Science.gov (United States)

    Walker, Vyvyca J; Agarwal, Anupam

    2016-01-01

    Iron is an essential metal involved in several major cellular processes required to maintain life. Because of iron's ability to cause oxidative damage, its transport, metabolism, and storage is strictly controlled in the body, especially in the small intestine, liver, and kidney. Iron plays a major role in acute kidney injury and has been a target for therapeutic intervention. However, the therapies that have been effective in animal models of acute kidney injury have not been successful in human beings. Targeting iron trafficking via ferritin, ferroportin, or hepcidin may offer new insights. This review focuses on the biology of iron, particularly in the kidney, and its implications in acute kidney injury. Copyright © 2016. Published by Elsevier Inc.

  7. Iron Homeostasis in Health and Disease

    Directory of Open Access Journals (Sweden)

    Raffaella Gozzelino

    2016-01-01

    Full Text Available Iron is required for the survival of most organisms, including bacteria, plants, and humans. Its homeostasis in mammals must be fine-tuned to avoid iron deficiency with a reduced oxygen transport and diminished activity of Fe-dependent enzymes, and also iron excess that may catalyze the formation of highly reactive hydroxyl radicals, oxidative stress, and programmed cell death. The advance in understanding the main players and mechanisms involved in iron regulation significantly improved since the discovery of genes responsible for hemochromatosis, the IRE/IRPs machinery, and the hepcidin-ferroportin axis. This review provides an update on the molecular mechanisms regulating cellular and systemic Fe homeostasis and their roles in pathophysiologic conditions that involve alterations of iron metabolism, and provides novel therapeutic strategies to prevent the deleterious effect of its deficiency/overload.

  8. Genetics Home Reference: iron-refractory iron deficiency anemia

    Science.gov (United States)

    ... refractory iron deficiency anemia iron-refractory iron deficiency anemia Enable Javascript to view the expand/collapse boxes. ... All Close All Description Iron-refractory iron deficiency anemia is one of many types of anemia , which ...

  9. Identification and Characterization of a Putative Manganese Export Protein in Vibrio cholerae.

    Science.gov (United States)

    Fisher, Carolyn R; Wyckoff, Elizabeth E; Peng, Eric D; Payne, Shelley M

    2016-10-15

    Manganese plays an important role in the cellular physiology and metabolism of bacterial species, including the human pathogen Vibrio cholerae The intracellular level of manganese ions is controlled through coordinated regulation of the import and export of this element. We have identified a putative manganese exporter (VC0022), named mneA (manganese exporter A), which is highly conserved among Vibrio spp. An mneA mutant exhibited sensitivity to manganese but not to other cations. Under high-manganese conditions, the mneA mutant showed an almost 50-fold increase in intracellular manganese levels and reduced intracellular iron relative to those of its wild-type parent, suggesting that the mutant's manganese sensitivity is due to the accumulation of toxic levels of manganese and reduced iron. Expression of mneA suppressed the manganese-sensitive phenotype of an Escherichia coli strain carrying a mutation in the nonhomologous manganese export gene, mntP, further supporting a manganese export function for V. cholerae MneA. The level of mneA mRNA was induced approximately 2.5-fold after addition of manganese to the medium, indicating regulation of this gene by manganese. This study offers the first insights into understanding manganese homeostasis in this important pathogen. Bacterial cells control intracellular metal concentrations by coordinating acquisition in metal-limited environments with export in metal-excess environments. We identified a putative manganese export protein, MneA, in Vibrio cholerae An mneA mutant was sensitive to manganese, and this effect was specific to manganese. The mneA mutant accumulated high levels of intracellular manganese with a concomitant decrease in intracellular iron levels when grown in manganese-supplemented medium. Expression of mneA in trans suppressed the manganese sensitivity of an E. coli mntP mutant. This study is the first to investigate manganese export in V. cholerae. Copyright © 2016, American Society for Microbiology

  10. Duodenal Absorption and Tissue Utilization of Dietary Heme and Nonheme Iron Differ in Rats123

    Science.gov (United States)

    Cao, Chang; Thomas, Carrie E.; Insogna, Karl L.; O'Brien, Kimberly O.

    2014-01-01

    Background: Dietary heme contributes to iron intake, yet regulation of heme absorption and tissue utilization of absorbed heme remains undefined. Objectives: In a rat model of iron overload, we used stable iron isotopes to examine heme- and nonheme-iron absorption in relation to liver hepcidin and to compare relative utilization of absorbed heme and nonheme iron by erythroid (RBC) and iron storage tissues (liver and spleen). Methods: Twelve male Sprague-Dawley rats were randomly assigned to groups for injections of either saline or iron dextran (16 or 48 mg Fe over 2 wk). After iron loading, rats were administered oral stable iron in the forms of 57Fe-ferrous sulfate and 58Fe-labeled hemoglobin. Expression of liver hepcidin and duodenal iron transporters and tissue stable iron enrichment was determined 10 d postdosing. Results: High iron loading increased hepatic hepcidin by 3-fold and reduced duodenal expression of divalent metal transporter 1 (DMT1) by 76%. Nonheme-iron absorption was 2.5 times higher than heme-iron absorption (P = 0.0008). Absorption of both forms of iron was inversely correlated with hepatic hepcidin expression (heme-iron absorption: r = −0.77, P = 0.003; nonheme-iron absorption: r = −0.80, P = 0.002), but hepcidin had a stronger impact on nonheme-iron absorption (P = 0.04). Significantly more 57Fe was recovered in RBCs (P = 0.02), and more 58Fe was recovered in the spleen (P = 0.01). Conclusions: Elevated hepcidin significantly decreased heme- and nonheme-iron absorption but had a greater impact on nonheme-iron absorption. Differential tissue utilization of heme vs. nonheme iron was evident between erythroid and iron storage tissues, suggesting that some heme may be exported into the circulation in a form different from that of nonheme iron. PMID:25332470

  11. Transcriptional profiling of Bacillus anthracis Sterne (34F2 during iron starvation.

    Directory of Open Access Journals (Sweden)

    Paul E Carlson

    Full Text Available Lack of available iron is one of many environmental challenges that a bacterium encounters during infection and adaptation to iron starvation is important for the pathogen to efficiently replicate within the host. Here we define the transcriptional response of B. anthracis Sterne (34F(2 to iron depleted conditions. Genome-wide transcript analysis showed that B. anthracis undergoes considerable changes in gene expression during growth in iron-depleted media, including the regulation of known and candidate virulence factors. Two genes encoding putative internalin proteins were chosen for further study. Deletion of either gene (GBAA0552 or GBAA1340 resulted in attenuation in a murine model of infection. This attenuation was amplified in a double mutant strain. These data define the transcriptional changes induced during growth in low iron conditions and illustrate the potential of this dataset in the identification of putative virulence determinants for future study.

  12. Iron-responsive olfactory uptake of manganese improves motor function deficits associated with iron deficiency.

    Directory of Open Access Journals (Sweden)

    Jonghan Kim

    Full Text Available Iron-responsive manganese uptake is increased in iron-deficient rats, suggesting that toxicity related to manganese exposure could be modified by iron status. To explore possible interactions, the distribution of intranasally-instilled manganese in control and iron-deficient rat brain was characterized by quantitative image analysis using T1-weighted magnetic resonance imaging (MRI. Manganese accumulation in the brain of iron-deficient rats was doubled after intranasal administration of MnCl(2 for 1- or 3-week. Enhanced manganese level was observed in specific brain regions of iron-deficient rats, including the striatum, hippocampus, and prefrontal cortex. Iron-deficient rats spent reduced time on a standard accelerating rotarod bar before falling and with lower peak speed compared to controls; unexpectedly, these measures of motor function significantly improved in iron-deficient rats intranasally-instilled with MnCl(2. Although tissue dopamine concentrations were similar in the striatum, dopamine transporter (DAT and dopamine receptor D(1 (D1R levels were reduced and dopamine receptor D(2 (D2R levels were increased in manganese-instilled rats, suggesting that manganese-induced changes in post-synaptic dopaminergic signaling contribute to the compensatory effect. Enhanced olfactory manganese uptake during iron deficiency appears to be a programmed "rescue response" with beneficial influence on motor impairment due to low iron status.

  13. Iron-Responsive Olfactory Uptake of Manganese Improves Motor Function Deficits Associated with Iron Deficiency

    Science.gov (United States)

    Kim, Jonghan; Li, Yuan; Buckett, Peter D.; Böhlke, Mark; Thompson, Khristy J.; Takahashi, Masaya; Maher, Timothy J.; Wessling-Resnick, Marianne

    2012-01-01

    Iron-responsive manganese uptake is increased in iron-deficient rats, suggesting that toxicity related to manganese exposure could be modified by iron status. To explore possible interactions, the distribution of intranasally-instilled manganese in control and iron-deficient rat brain was characterized by quantitative image analysis using T1-weighted magnetic resonance imaging (MRI). Manganese accumulation in the brain of iron-deficient rats was doubled after intranasal administration of MnCl2 for 1- or 3-week. Enhanced manganese level was observed in specific brain regions of iron-deficient rats, including the striatum, hippocampus, and prefrontal cortex. Iron-deficient rats spent reduced time on a standard accelerating rotarod bar before falling and with lower peak speed compared to controls; unexpectedly, these measures of motor function significantly improved in iron-deficient rats intranasally-instilled with MnCl2. Although tissue dopamine concentrations were similar in the striatum, dopamine transporter (DAT) and dopamine receptor D1 (D1R) levels were reduced and dopamine receptor D2 (D2R) levels were increased in manganese-instilled rats, suggesting that manganese-induced changes in post-synaptic dopaminergic signaling contribute to the compensatory effect. Enhanced olfactory manganese uptake during iron deficiency appears to be a programmed “rescue response” with beneficial influence on motor impairment due to low iron status. PMID:22479410

  14. OsYSL16 plays a role in the allocation of iron

    OpenAIRE

    2012-01-01

    Graminaceous plants acquire iron by secreting mugineic acid family phytosiderophores into the rhizosphere and taking up complexes of iron and phytosiderophores through YSL (yellow stripe 1-like) transporters. Rice OsYSL15 is a transporter of the iron(III)-2′-deoxymugineic acid complex. OsYSL16 has 85 % similarity to both OsYSL15 and the iron(II)-nicotianamine transporter OsYSL2. In the present study, we show that OsYSL16 functionally complemented a yeast mutant defective in iron uptake when g...

  15. Putative bronchopulmonary flagellated protozoa in immunosuppressed patients.

    Science.gov (United States)

    Kilimcioglu, Ali Ahmet; Havlucu, Yavuz; Girginkardesler, Nogay; Celik, Pınar; Yereli, Kor; Özbilgin, Ahmet

    2014-01-01

    Flagellated protozoa that cause bronchopulmonary symptoms in humans are commonly neglected. These protozoal forms which were presumed to be "flagellated protozoa" have been previously identified in immunosuppressed patients in a number of studies, but have not been certainly classified so far. Since no human cases of bronchopulmonary flagellated protozoa were reported from Turkey, we aimed to investigate these putative protozoa in immunosuppressed patients who are particularly at risk of infectious diseases. Bronchoalveolar lavage fluid samples of 110 immunosuppressed adult patients who were admitted to the Department of Chest Diseases, Hafsa Sultan Hospital of Celal Bayar University, Manisa, Turkey, were examined in terms of parasites by light microscopy. Flagellated protozoal forms were detected in nine (8.2%) of 110 cases. Metronidazole (500 mg b.i.d. for 30 days) was given to all positive cases and a second bronchoscopy was performed at the end of the treatment, which revealed no parasites. In conclusion, immunosuppressed patients with bronchopulmonary symptoms should attentively be examined with regard to flagellated protozoa which can easily be misidentified as epithelial cells.

  16. The Biogeography of Putative Microbial Antibiotic Production.

    Directory of Open Access Journals (Sweden)

    Hélène Morlon

    Full Text Available Understanding patterns in the distribution and abundance of functional traits across a landscape is of fundamental importance to ecology. Mapping these distributions is particularly challenging for species-rich groups with sparse trait measurement coverage, such as flowering plants, insects, and microorganisms. Here, we use likelihood-based character reconstruction to infer and analyze the spatial distribution of unmeasured traits. We apply this framework to a microbial dataset comprised of 11,732 ketosynthase alpha gene sequences extracted from 144 soil samples from three continents to document the spatial distribution of putative microbial polyketide antibiotic production. Antibiotic production is a key competitive strategy for soil microbial survival and performance. Additionally, novel antibiotic discovery is highly relevant to human health, making natural antibiotic production by soil microorganisms a major target for bioprospecting. Our comparison of trait-based biogeographical patterns to patterns based on taxonomy and phylogeny is relevant to our basic understanding of microbial biogeography as well as the pressing need for new antibiotics.

  17. Mechanosensory neurons, cutaneous mechanoreceptors, and putative mechanoproteins.

    Science.gov (United States)

    Del Valle, M E; Cobo, T; Cobo, J L; Vega, J A

    2012-08-01

    The mammalian skin has developed sensory structures (mechanoreceptors) that are responsible for different modalities of mechanosensitivity like touch, vibration, and pressure sensation. These specialized sensory organs are anatomically and functionally connected to a special subset of sensory neurons called mechanosensory neurons, which electrophysiologically correspond with Aβ fibers. Although mechanosensory neurons and cutaneous mechanoreceptors are rather well known, the biology of the sense of touch still remains poorly understood. Basically, the process of mechanosensitivity requires the conversion of a mechanical stimulus into an electrical signal through the activation of ion channels that gate in response to mechanical stimuli. These ion channels belong primarily to the family of the degenerin/epithelium sodium channels, especially the subfamily acid-sensing ion channels, and to the family of transient receptor potential channels. This review compiles the current knowledge on the occurrence of putative mechanoproteins in mechanosensory neurons and mechanoreceptors, as well as the involvement of these proteins on the biology of touch. Furthermore, we include a section about what the knock-out mice for mechanoproteins are teaching us. Finally, the possibilities for mechanotransduction in mechanoreceptors, and the common involvement of the ion channels, extracellular membrane, and cytoskeleton, are revisited.

  18. Iron deficiency in heart failure: a practical guide.

    Science.gov (United States)

    Ebner, Nicole; von Haehling, Stephan

    2013-09-23

    Iron is an element necessary for cells due to its capacity of transporting oxygen and electrons. One of the important co-morbidities in heart failure is iron deficiency. Iron has relevant biological functions, for example, the formation of haemoglobin, myoglobin and numerous enzymatic groups. The prevalence of iron deficiency increases with the severity of heart failure. For a long time, the influence of iron deficiency was underestimated especially in terms of worsening of cardiovascular diseases and of developing anaemia. In recent years, studies with intravenous iron agents in patients with iron deficiency and cardiovascular diseases indicated new insights in the improvement of therapy. Experimental studies support the understanding of iron metabolism. Many physicians remain doubtful of the use of intravenous iron due to reports of side effects. The aim of this review is to describe iron metabolism in humans, to highlight the influence of iron deficiency on the course and symptoms of heart failure, discuss diagnostic tools of iron deficiency and provide guidance on the use of intravenous iron.

  19. Iron Deficiency in Heart Failure: A Practical Guide

    Directory of Open Access Journals (Sweden)

    Nicole Ebner

    2013-09-01

    Full Text Available Iron is an element necessary for cells due to its capacity of transporting oxygen and electrons. One of the important co-morbidities in heart failure is iron deficiency. Iron has relevant biological functions, for example, the formation of haemoglobin, myoglobin and numerous enzymatic groups. The prevalence of iron deficiency increases with the severity of heart failure. For a long time, the influence of iron deficiency was underestimated especially in terms of worsening of cardiovascular diseases and of developing anaemia. In recent years, studies with intravenous iron agents in patients with iron deficiency and cardiovascular diseases indicated new insights in the improvement of therapy. Experimental studies support the understanding of iron metabolism. Many physicians remain doubtful of the use of intravenous iron due to reports of side effects. The aim of this review is to describe iron metabolism in humans, to highlight the influence of iron deficiency on the course and symptoms of heart failure, discuss diagnostic tools of iron deficiency and provide guidance on the use of intravenous iron.

  20. Iron from Zealandic bog iron ore -

    DEFF Research Database (Denmark)

    Lyngstrøm, Henriette Syrach

    2011-01-01

    og geologiske materiale, metallurgiske analyser og eksperimentel arkæologiske forsøg - konturerne af en jernproduktion med udgangspunkt i den sjællandske myremalm. The frequent application by archaeologists of Werner Christensen’s distribution map for the occurrence of bog iron ore in Denmark (1966...... are sketched of iron production based on bog iron ore from Zealand....

  1. The Mycobacterium tuberculosis high-affinity iron importer, IrtA, contains an FAD-binding domain.

    Science.gov (United States)

    Ryndak, Michelle B; Wang, Shuishu; Smith, Issar; Rodriguez, G Marcela

    2010-02-01

    Iron is an essential nutrient not freely available to microorganisms infecting mammals. To overcome iron deficiency, bacteria have evolved various strategies including the synthesis and secretion of high-affinity iron chelators known as siderophores. The siderophores produced and secreted by Mycobacterium tuberculosis, exomycobactins, compete for iron with host iron-binding proteins and, together with the iron-regulated ABC transporter IrtAB, are required for the survival of M. tuberculosis in iron deficient conditions and for normal replication in macrophages and in mice. This study further characterizes the role of IrtAB in M. tuberculosis iron acquisition. Our results demonstrate a role for IrtAB in iron import and show that the amino terminus domain of IrtA is a flavin-adenine dinucleotide-binding domain essential for iron acquisition. These results suggest a model in which the amino terminus of IrtA functions to couple iron transport and assimilation.

  2. 76 FR 68523 - Utah Southern Railroad Company, LLC-Change in Operators Exemption-Iron Bull Railroad Company, LLC

    Science.gov (United States)

    2011-11-04

    ... near Iron Springs, Utah, and milepost 14.7 at or near Iron Mountain, Utah, a distance of 14.6 miles in... Surface Transportation Board Utah Southern Railroad Company, LLC--Change in Operators Exemption--Iron Bull... of exemption under 49 CFR 1150.31 to change operators from Iron Bull Railroad Company (IBRC) to USRC...

  3. Control of bacterial iron homeostasis by manganese

    Science.gov (United States)

    Puri, Sumant; Hohle, Thomas H.; O'Brian, Mark R.

    2010-01-01

    Perception and response to nutritional iron availability by bacteria are essential to control cellular iron homeostasis. The Irr protein from Bradyrhizobium japonicum senses iron through the status of heme biosynthesis to globally regulate iron-dependent gene expression. Heme binds directly to Irr to trigger its degradation. Here, we show that severe manganese limitation created by growth of a Mn2+ transport mutant in manganese-limited media resulted in a cellular iron deficiency. In wild-type cells, Irr levels were attenuated under manganese limitation, resulting in reduced promoter occupancy of target genes and altered iron-dependent gene expression. Irr levels were high regardless of manganese availability in a heme-deficient mutant, indicating that manganese normally affects heme-dependent degradation of Irr. Manganese altered the secondary structure of Irr in vitro and inhibited binding of heme to the protein. We propose that manganese limitation destabilizes Irr under low-iron conditions by lowering the threshold of heme that can trigger Irr degradation. The findings implicate a mechanism for the control of iron homeostasis by manganese in a bacterium. PMID:20498065

  4. Obesity Promotes Alterations in Iron Recycling

    Directory of Open Access Journals (Sweden)

    Marta Citelli

    2015-01-01

    Full Text Available Hepcidin is a key hormone that induces the degradation of ferroportin (FPN, a protein that exports iron from reticuloendothelial macrophages and enterocytes. The aim of the present study was to experimentally evaluate if the obesity induced by a high-fat diet (HFD modifies the expression of FPN in macrophages and enterocytes, thus altering the iron bioavailability. In order to directly examine changes associated with iron metabolism in vivo, C57BL/6J mice were fed either a control or a HFD. Serum leptin levels were evaluated. The hepcidin, divalent metal transporter-1 (DMT1, FPN and ferritin genes were analyzed by real-time polymerase chain reaction. The amount of iron present in both the liver and spleen was determined by flame atomic absorption spectrometry. Ferroportin localization within reticuloendothelial macrophages was observed by immunofluorescence microscopy. Obese animals were found to exhibit increased hepcidin gene expression, while iron accumulated in the spleen and liver. They also exhibited changes in the sublocation of splenic cellular FPN and a reduction in the FPN expression in the liver and the spleen, while no changes were observed in enterocytes. Possible explanations for the increased hepcidin expression observed in HFD animals may include: increased leptin levels, the liver iron accumulation or endoplasmic reticulum (ER stress. Together, the results indicated that obesity promotes changes in iron bioavailability, since it altered the iron recycling function.

  5. Iron and genome stability: An update

    Energy Technology Data Exchange (ETDEWEB)

    Pra, Daniel, E-mail: daniel_pra@yahoo.com [PPG em Promocao da Saude, Universidade de Santa Cruz do Sul (UNISC), Santa Cruz do Sul, RS (Brazil); PPG em Saude e Comportamento, Universidade Catolica de Pelotas, Pelotas, RS (Brazil); Franke, Silvia Isabel Rech [PPG em Promocao da Saude, Universidade de Santa Cruz do Sul (UNISC), Santa Cruz do Sul, RS (Brazil); Henriques, Joao Antonio Pegas [Instituto de Biotecnologia, Universidade de Caxias do Sul, Caxias do Sul, RS (Brazil); Fenech, Michael [CSIRO Food and Nutritional Sciences, Adelaide, SA (Australia)

    2012-05-01

    Iron is an essential micronutrient which is required in a relatively narrow range for maintaining metabolic homeostasis and genome stability. Iron participates in oxygen transport and mitochondrial respiration as well as in antioxidant and nucleic acid metabolism. Iron deficiency impairs these biological pathways, leading to oxidative stress and possibly carcinogenesis. Iron overload has been linked to genome instability as well as to cancer risk increase, as seen in hereditary hemochromatosis. Iron is an extremely reactive transition metal that can interact with hydrogen peroxide to generate hydroxyl radicals that form the 8-hydroxy-guanine adduct, cause point mutations as well as DNA single and double strand breaks. Iron overload also induces DNA hypermethylation and can reduce telomere length. The current Recommended Dietary Allowances (RDA) for iron, according with Institute of Medicine Dietary Reference Intake (DRI), is based in the concept of preventing anemia, and ranges from 7 mg/day to 18 mg/day depending on life stage and gender. Pregnant women need 27 mg/day. The maximum safety level for iron intake, the Upper Level (UL), is 40-45 mg/day, based on the prevention of gastrointestinal distress associated to high iron intakes. Preliminary evidence indicates that 20 mg/day iron, an intake slightly higher than the RDA, may reduce the risk of gastrointestinal cancer in the elderly as well as increasing genome stability in lymphocytes of children and adolescents. Current dietary recommendations do not consider the concept of genome stability which is of concern because damage to the genome has been linked to the origin and progression of many diseases and is the most fundamental pathology. Given the importance of iron for homeostasis and its potential influence over genome stability and cancer it is recommended to conduct further studies that conclusively define these relationships.

  6. Iron isotope composition of some Archean and Proterozoic iron formations

    Science.gov (United States)

    Planavsky, Noah; Rouxel, Olivier J.; Bekker, Andrey; Hofmann, Axel; Little, Crispin T. S.; Lyons, Timothy W.

    2012-03-01

    Fe isotopes can provide new insight into redox-dependent biogeochemical processes. Precambrian iron formations (IF) are deserving targets for Fe isotope studies because they are composed predominantly of authigenic Fe phases and record a period of unprecedented iron deposition in Earth's history. We present Fe isotope data for bulk samples from 24 Archean and Proterozoic IF and eight Phanerozoic Fe oxide-rich deposits. These data reveal that many Archean and early Paleoproterozoic iron formations were a sink for isotopically heavy Fe, in contrast to later Proterozoic and Phanerozoic Fe oxide-rich rocks. The positive δ56Fe values in IF are best explained by delivery of particulate ferric oxides formed in the water column to the sediment-water interface. Because IF are a net sink for isotopically heavy Fe, there must be a corresponding pool of isotopically light Fe in the sedimentary record. Earlier work suggested that Archean pyritic black shales were an important part of this light sink before 2.35 billion years ago (Ga). It is therefore likely that the persistently and anomalously low δ56Fe values in shales are linked with the deposition of isotopically heavy Fe in IF in the deeper parts of basins. IF deposition produced a residual isotopically light dissolved Fe pool that was captured by pyritic Fe in shales. Local dissimilatory Fe reduction in porewater and associated diagenetic reactions resulting in pyrite and carbonate precipitation may have further enhanced Fe isotope heterogeneity in marine sediments, and an 'iron shuttle' may have transported isotopically light Fe from shelf sediments to the basin. Nevertheless, water-column processing of hydrothermally delivered Fe likely had the strongest influence on the bulk iron isotope composition of Archean and Paleoproterozoic iron formations and other marine sediments.

  7. [Iron-refractory iron deficiency anemia].

    Science.gov (United States)

    Kawabata, Hiroshi

    2016-02-01

    The major causes of iron deficiency anemia (IDA) include iron loss due to bleeding, increased iron requirements, and decreased iron absorption by the intestine. The most common cause of IDA in Japanese women is iron loss during menstruation. Autoimmune atrophic gastritis and Helicobacter pylori infection can also cause IDA by reducing intestinal iron absorption. In addition to these common etiologies, germline mutations of TMPRSS6 can cause iron-refractory IDA (IRIDA). TMPRSS6 encodes matriptase-2, a membrane-bound serine protease primarily expressed in the liver. Functional loss of matriptase-2 due to homozygous mutations results in an increase in the expression of hepcidin, which is the key regulator of systemic iron homeostasis. The serum hepcidin increase in turn leads to a decrease in iron supply from the intestine and macrophages to erythropoietic cells. IRIDA is microcytic and hypochromic, but decreased serum ferritin is not observed as in IDA. IRIDA is refractory to oral iron supplementation, but does respond to intravenous iron supplementation to some extent. Because genetic testing is required for the diagnoses of IRIDA, a considerable number of cases may go undiagnosed and may thus be overlooked.

  8. Nutritional iron deficiency

    NARCIS (Netherlands)

    Zimmermann, M.B.; Hurrell, R.F.

    2007-01-01

    Iron deficiency is one of the leading risk factors for disability and death worldwide, affecting an estimated 2 billion people. Nutritional iron deficiency arises when physiological requirements cannot be met by iron absorption from diet. Dietary iron bioavailability is low in populations consuming

  9. Iron deficiency anemia

    Science.gov (United States)

    Anemia - iron deficiency ... iron from old red blood cells. Iron deficiency anemia develops when your body's iron stores run low. ... You may have no symptoms if the anemia is mild. Most of the time, ... slowly. Symptoms may include: Feeling weak or tired more often ...

  10. Nutritional iron deficiency

    NARCIS (Netherlands)

    Zimmermann, M.B.; Hurrell, R.F.

    2007-01-01

    Iron deficiency is one of the leading risk factors for disability and death worldwide, affecting an estimated 2 billion people. Nutritional iron deficiency arises when physiological requirements cannot be met by iron absorption from diet. Dietary iron bioavailability is low in populations consuming

  11. Serum iron test

    Science.gov (United States)

    Fe+2; Ferric ion; Fe++; Ferrous ion; Iron - serum; Anemia - serum iron; Hemochromatosis - serum iron ... A blood sample is needed. Iron levels are highest in the morning. Your health care provider will likely have you do this test in the morning.

  12. Iron stress in plants.

    Science.gov (United States)

    Connolly, Erin L; Guerinot, Mary

    2002-07-30

    Although iron is an essential nutrient for plants, its accumulation within cells can be toxic. Plants, therefore, respond to both iron deficiency and iron excess by inducing expression of different gene sets. Here, we review recent advances in the understanding of iron homeostasis in plants gained through functional genomic approaches

  13. Iron stress in plants

    OpenAIRE

    Connolly, Erin L.; Guerinot, Mary Lou

    2002-01-01

    Although iron is an essential nutrient for plants, its accumulation within cells can be toxic. Plants, therefore, respond to both iron deficiency and iron excess by inducing expression of different gene sets. Here, we review recent advances in the understanding of iron homeostasis in plants gained through functional genomic approaches.

  14. Urinary iron excretion test in iron deficiency anemia.

    Directory of Open Access Journals (Sweden)

    Kimura,Ikuro

    1980-02-01

    Full Text Available A urinary iron excretion test was carried out in 22 patients with iron deficiency anemia. The iron excretion index was significantly higher in patients with intractable iron deficiency anemia compared with normal subjects and anemic patients who were responsive to iron therapy. The findings suggest that iron excretion may be a factor that modulates the response of patients to iron therapy.

  15. Blood-brain barrier flux of aluminum, manganese, iron and other metals suspected to contribute to metal-induced neurodegeneration.

    Science.gov (United States)

    Yokel, Robert A

    2006-11-01

    The etiology of many neurodegenerative diseases has been only partly attributed to acquired traits, suggesting environmental factors may also contribute. Metal dyshomeostasis causes or has been implicated in many neurodegenerative diseases. Metal flux across the blood-brain barrier (the primary route of brain metal uptake) and the choroid plexuses as well as sensory nerve metal uptake from the nasal cavity are reviewed. Transporters that have been described at the blood-brain barrier are listed to illustrate the extensive possibilities for moving substances into and out of the brain. The controversial role of aluminum in Alzheimer's disease, evidence suggesting brain aluminum uptake by transferrin-receptor mediated endocytosis and of aluminum citrate by system Xc;{-} and an organic anion transporter, and results suggesting transporter-mediated aluminum brain efflux are reviewed. The ability of manganese to produce a parkinsonism-like syndrome, evidence suggesting manganese uptake by transferrin- and non-transferrin-dependent mechanisms which may include store-operated calcium channels, and the lack of transporter-mediated manganese brain efflux, are discussed. The evidence for transferrin-dependent and independent mechanisms of brain iron uptake is presented. The copper transporters, ATP7A and ATP7B, and their roles in Menkes and Wilson's diseases, are summarized. Brain zinc uptake is facilitated by L- and D-histidine, but a transporter, if involved, has not been identified. Brain lead uptake may involve a non-energy-dependent process, store-operated calcium channels, and/or an ATP-dependent calcium pump. Methyl mercury can form a complex with L-cysteine that mimics methionine, enabling its transport by the L system. The putative roles of zinc transporters, ZnT and Zip, in regulating brain zinc are discussed. Although brain uptake mechanisms for some metals have been identified, metal efflux from the brain has received little attention, preventing integration of

  16. Diversity and Evolutionary History of Iron Metabolism Genes in Diatoms.

    Science.gov (United States)

    Groussman, Ryan D; Parker, Micaela S; Armbrust, E Virginia

    2015-01-01

    Ferroproteins arose early in Earth's history, prior to the emergence of oxygenic photosynthesis and the subsequent reduction of bioavailable iron. Today, iron availability limits primary productivity in about 30% of the world's oceans. Diatoms, responsible for nearly half of oceanic primary production, have evolved molecular strategies for coping with variable iron concentrations. Our understanding of the evolutionary breadth of these strategies has been restricted by the limited number of species for which molecular sequence data is available. To uncover the diversity of strategies marine diatoms employ to meet cellular iron demands, we analyzed 367 newly released marine microbial eukaryotic transcriptomes, which include 47 diatom species. We focused on genes encoding proteins previously identified as having a role in iron management: iron uptake (high-affinity ferric reductase, multi-copper oxidase, and Fe(III) permease); iron storage (ferritin); iron-induced protein substitutions (flavodoxin/ferredoxin, and plastocyanin/cytochrome c6) and defense against reactive oxygen species (superoxide dismutases). Homologs encoding the high-affinity iron uptake system components were detected across the four diatom Classes suggesting an ancient origin for this pathway. Ferritin transcripts were also detected in all Classes, revealing a more widespread utilization of ferritin throughout diatoms than previously recognized. Flavodoxin and plastocyanin transcripts indicate possible alternative redox metal strategies. Predicted localization signals for ferredoxin identify multiple examples of gene transfer from the plastid to the nuclear genome. Transcripts encoding four superoxide dismutase metalloforms were detected, including a putative nickel-coordinating isozyme. Taken together, our results suggest that the majority of iron metabolism genes in diatoms appear to be vertically inherited with functional diversity achieved via possible neofunctionalization of paralogs. This

  17. Influence of Atmospheric Processes on the Solubility and Composition of Iron in Saharan Dust

    Science.gov (United States)

    Ingall, E. D.; Longo, A.; Feng, Y.; Lai, B.; Landing, W. M.; Shelley, R.; Nenes, A.; Mihalopoulos, N.; Violaki, K.

    2016-12-01

    Iron is a key micronutrient that is vital for all organisms. The supply of bioavailable, soluble iron controls primary productivity in approximately 30% of the world's oceans. The significant contribution of atmospheric aerosols to the bioavailable iron budget in vast ocean regions, underscores the need to understand the controls and transformations of aerosol iron solubility during atmospheric transport. The Sahara Desert contains the largest and most active sources of aerosol dust globally and can be a key source of nutrients to the Mediterranean Sea, much of the North Atlantic Ocean, and even as far as the Gulf of Mexico. Aerosol iron was examined in Saharan dust plumes using a combination of iron near-edge X-ray absorption spectroscopy and wet chemical techniques. Aerosol samples were collected at three sites located in the Mediterranean, the Atlantic, and Bermuda to characterize iron at different atmospheric transport lengths and time scales. Iron(III) oxides were a component of aerosols at all sampling sites and dominated aerosol iron in Mediterranean samples. In Atlantic samples, iron(II & III) sulfate, iron(III) phosphate, and iron(II) silicates were also contributors to aerosol composition. With increased atmospheric transport time, iron(II) sulfates are found to become more abundant, aerosol iron oxidation state became more reduced, and aerosol acidity increased. Atmospheric processing, including acidic reactions and photo-reduction, likely influence the form of iron minerals and the oxidation state in Saharan dust aerosols and contribute to increases in aerosol iron solubility. Overall, these findings suggest that a combination of factors affects aerosol iron solubility during long-distance atmospheric transport and emphasize the need to consider reductive mechanisms as well as proton-induced solubilization of aerosol iron in modeling studies.