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Sample records for manganese ii induces

  1. Manganese (II) induces chemical hypoxia by inhibiting HIF-prolyl hydroxylase: Implication in manganese-induced pulmonary inflammation

    SciTech Connect

    Han, Jeongoh; Lee, Jong-Suk; Choi, Daekyu; Lee, Youna; Hong, Sungchae; Choi, Jungyun; Han, Songyi; Ko, Yujin; Kim, Jung-Ae; Mi Kim, Young; Jung, Yunjin

    2009-03-15

    Manganese (II), a transition metal, causes pulmonary inflammation upon environmental or occupational inhalation in excess. We investigated a potential molecular mechanism underlying manganese-induced pulmonary inflammation. Manganese (II) delayed HIF-1{alpha} protein disappearance, which occurred by inhibiting HIF-prolyl hydroxylase (HPH), the key enzyme for HIF-1{alpha} hydroxylation and subsequent von Hippel-Lindau(VHL)-dependent HIF-1{alpha} degradation. HPH inhibition by manganese (II) was neutralized significantly by elevated dose of iron. Consistent with this, the induction of cellular HIF-1{alpha} protein by manganese (II) was abolished by pretreatment with iron. Manganese (II) induced the HIF-1 target gene involved in pulmonary inflammation, vascular endothelial growth factor (VEGF), in lung carcinoma cell lines. The induction of VEGF was dependent on HIF-1. Manganese-induced VEGF promoted tube formation of HUVEC. Taken together, these data suggest that HIF-1 may be a potential mediator of manganese-induced pulmonary inflammation.

  2. Conversion of the spin state of the manganese complex in photosystem II induced by near-infrared light.

    PubMed

    Boussac, A; Girerd, J J; Rutherford, A W

    1996-06-04

    The manganese complex (Mn4) which is responsible for water oxidation in photosystem II is EPR detectable in the S2 state, one of the five redox states of the enzyme cycle. The S2 state is observable at 10 K either as a multiline signal (spin 1/2) or as a signal at g = 4.1 (spin 3/2 or spin 5/2). It is shown here that at around 150 K the state responsible for the multiline signal is converted to that responsible for the g = 4.1 signal upon the absorption of infrared light. This conversion is fully reversible at 200 K. The action spectrum of this conversion has its maximum at 820 nm (12 200 cm-1) and is similar to the intervalence charge transfer band in di-mu-oxo-(MnIIIMnIV) model systems. It is suggested that the conversion of the multiline signal to the g = 4.1 signal results from absorption of infrared light by the Mn cluster itself, resulting in electron transfer from MnIII to MnIV. The g = 4.1 signal is thus proposed to arise from a state which differs from that which gives rise to the multiline signal only in terms of this change in its valence distribution. The near-infrared light effect was observed in the S2 state of Sr(2+)-reconstituted photosystem II and in Ca(2+)-depleted, EGTA (or citrate-)-treated photosystem II but not in ammonia-treated photosystem II. Earlier results in the literature which showed that the g = 4.1 state was preferentially formed by illumination at 130 K are reinterpreted as being the result of two photochemical events: the first being photosynthetic charge separation resulting in an S2 state which gives rise to the multiline signal and the second being the conversion of this state to the g = 4.1 state due to the simultaneous and inadvertent presence of 820 nm light in the broad-band illumination given. There is therefore no reason to consider the state responsible for the g = 4.1 signal as a precursor of that which gives rise to the multiline signal.

  3. Manganese(II) induces cell division and increases in superoxide dismutase and catalase activities in an aging deinococcal culture

    SciTech Connect

    Chou, F.I.; Tan, S.T. )

    1990-04-01

    Addition of Mn(II) at 2.5 microM or higher to stationary-phase cultures of Deinococcus radiodurans IR was found to trigger at least three rounds of cell division. This Mn(II)-induced cell division (Mn-CD) did not occur when the culture was in the exponential or death phase. The Mn-CD effect produced daughter cells proportionally reduced in size, pigmentation, and radioresistance but proportionally increased in activity and amount of the oxygen toxicity defense enzymes superoxide dismutase and catalase. In addition, the concentration of an Mn-CD-induced protein was found to remain high throughout the entire Mn-CD phase. It was also found that an untreated culture exhibited a growth curve characterized by a very rapid exponential-stationary transition and that cells which had just reached the early stationary phase were synchronous. Our results suggest the presence of an Mn(II)-sensitive mechanism for controlling cell division. The Mn-CD effect appears to be specific to the cation Mn(II) and the radioresistant bacteria, deinococci.

  4. Acute Toxicity and Gastroprotection Studies of a New Schiff Base Derived Manganese (II) Complex against HCl/Ethanol-Induced Gastric Ulcerations in Rats

    PubMed Central

    Ibrahim, Mohamed Yousif; Hashim, Najihah Mohd; Dhiyaaldeen, Summaya M.; Al-Obaidi, Mazen M.Jamil; El-Ferjani, Rashd M.; Adam, Hoyam; Alkotaini, Bassam; Batran, Rami Al; Ali, Hapipah Mohd

    2016-01-01

    Manganese is a crucial element for health. In this study, the gastroprotective efficacy of Mn (II) complex (MDLA) against acidified ethanol (HCl/Ethanol)-induced gastric ulceration in rats was evaluated. The animals were distributed into 5 groups. Groups 1 and 2 received carboxymethylcellulose (CMC), group 3 was pretreated with omeprazole, and groups 4 and 5 were given 10 and 20 mg/kg of MDLA, respectively. After one hour, CMC and HCl/Ethanol were given to groups 2–5 whilst the animals in group 1 were ingested with CMC. After sacrifice, gastric lesions were evaluated by wall mucus, gross appearance, histology, antioxidant enzymes and immunohistochemistry. Group 2 displayed severe gastric damage with a significant reduction in wall mucus. Conversely, gastric lesions were reduced in groups 3–5 by 85.72%, 56.51% and 65.93%, respectively. The rats in groups 3–5 showed up-regulation of heat shock protein 70 (Hsp70) with down-regulation of Bcl-2-associated protein x (Bax). Pretreatment with omeprazole or MDLA led to an increase in the uptake of Periodic Acid Schiff (PAS) stain in the glandular part of the gastric tissue, raised levels of prostaglandin E2 (PGE2) and superoxide dismutase (SOD), and a reduction in malondialdehyde (MDA) concentrations. These results suggested the gastroprotective action of Mn (II) complex. PMID:27229938

  5. Flash-induced consumption of molecular oxygen on the donor side of photosystem II in Mn-depleted subchloroplast membrane fragments: specific effects of manganese and calcium ions.

    PubMed

    Yanykin, D V; Khorobrykh, A A; Khorobrykh, S A; Pshybytko, N L; Klimov, V V

    2013-11-01

    It has been shown that removal of manganese from the water-oxidizing complex (WOC) of photosystem II (PSII) leads to flash-induced oxygen consumption (FIOC) which is activated by low concentration of Mn(2+) (Yanykin et al., Biochim Biophys Acta 1797:516-523, 2010). In the present work, we examined the effect of transition and non-transition divalent metal ions on FIOC in Mn-depleted PSII (apo-WOC-PSII) preparations. It was shown that only Mn(2+) ions are able to activate FIOC while other transition metal ions (Fe(2+), V(2+) and Cr(2+)) capable of electron donation to the apo-WOC-PSII suppressed the photoconsumption of O2. Co(2+) ions with a high redox potential (E (0) for Co(2+)/Co(3+) is 1.8 V) showed no effect. Non-transition metal ions Ca(2+) by Mg(2+) did not stimulate FIOC. However, Ca(2+) (in contrast to Mg(2+)) showed an additional activation effect in the presence of exogenic Mn(2+). The Ca(2+) effect depended on the concentration of both Mn(2+) and Ca(2+). The Ca effect was only observed when: (1) the activation of FIOC induced by Mn(2+) did not reach its maximum, (2) the concentration of Ca(2+) did not exceed 40 μM; at higher concentrations Ca(2+) inhibited the Mn(2+)-activated O2 photoconsumption. Replacement of Ca(2+) by Mg(2+) led to a suppression of Mn(2+)-activated O2 photoconsumption; while, addition of Ca(2+) resulted in elimination of the Mg(2+) inhibitory effect and activation of FIOC. Thus, only Mn(2+) and Ca(2+) (which are constituents of the WOC) have specific effects of activation of FIOC in apo-WOC-PSII preparations. Possible reactions involving Mn(2+) and Ca(2+) which could lead to the activation of FIOC in the apo-WOC-PSII are discussed.

  6. The S0 state of photosystem II induced by hydroxylamine: differences between the structure of the manganese complex in the S0 and S1 states determined by X-ray absorption spectroscopy.

    PubMed

    Guiles, R D; Yachandra, V K; McDermott, A E; Cole, J L; Dexheimer, S L; Britt, R D; Sauer, K; Klein, M P

    1990-01-16

    Hydroxylamine at low concentrations causes a two-flash delay in the first maximum flash yield of oxygen evolved from spinach photosystem II (PSII) subchloroplast membranes that have been excited by a series of saturating flashes of light. Untreated PSII membrane preparations exhibit a multiline EPR signal assigned to a manganese cluster and associated with the S2 state when illuminated at 195 K, or at 273 K in the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU). We used the extent of suppression of the multiline EPR signal observed in samples illuminated at 195 K to determine the fraction of PSII reaction centers set back to a hydroxylamine-induced S0-like state, which we designate S0*. The manganese K-edge X-ray absorption edges for dark-adapted PSII preparations with or without hydroxylamine are virtually identical. This indicates that, despite its high binding affinity to the oxygen-evolving complex (OEC) in the dark, hydroxylamine does not reduce chemically the manganese cluster within the OEC in the dark. After a single turnover of PSII, a shift to lower energy is observed in the inflection of the Mn K-edge of the manganese cluster. We conclude that, in the presence of hydroxylamine, illumination causes a reduction of the OEC, resulting in a state resembling S0. This lower Mn K-edge energy of S0*, relative to the edge of S1, implies the storage and stabilization of an oxidative equivalent within the manganese cluster during the S0----S1 state transition. An analysis of the extended X-ray absorption fine structure (EXAFS) of the S0* state indicates that a significant structural rearrangement occurs between the S0* and S1 states. The X-ray absorption edge position and the structure of the manganese cluster in the S0* state are indicative of a heterogeneous mixture of formal valences of manganese including one Mn(II) which is not present in the S1 state.

  7. The S sub 0 state of photosystem II induced by hydroxylamine: Differences between the structure of the manganese complex in the S sub 0 and S sub 1 states determined by X-ray absorption spectroscopy

    SciTech Connect

    Guiles, R.D.; Yachandra, V.K.; McDermott, A.E.; Cole, J.L.; Dexheimer, S.L.; Britt, R.D.; Sauer, K.; Klein, M.P. )

    1990-01-16

    Hydroxylamine at low concentrations causes a two-flash delay in the first delay in the first maximum flash yield oxygen evolved from spinach photosystem II (PSII) subchloroplast membranes that have been excited by a series of saturating flashes of light. Untreated PSII membrane preparations exhibit a multiline EPR signal assigned to a manganese cluster and associated with the S{sub 2} state when illuminated at 195 K, or at 273 K in the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU). The authors used the extent of suppression of the multiline EPR signal observed in samples illuminated at 195 K to determine the fraction of PSII reaction centers set back to a hydroxylamine-induced S{sub 0}-like state, which they designate S{sub 0}. The manganese K-edge X-ray absorption edges for dark-adapted PSII preparations with or without hydroxylamine are virtually identical. This indicates that, despite its high binding affinity to the oxygen-evolving complex (OEC) in the dark, hydroxylamine does not reduce chemically the manganese cluster within the OEC in the dark. After a single turnover of PSII a shift to lower energy is observed in the inflection of the Mn K-edge of the manganese cluster. They conclude that, in the presence of hydroxylamine, illumination causes a reduction of the OEC, resulting in a state resembling S{sub 0}. This lower Mn K-edge energy of S{sub 0}, relative to the edge of S{sub 1}, implies that storage and stabilization of an oxidative equivalent within the manganese cluster during the S{sub 0} {yields} S{sub 1} state transition. An analysis of the extended X-ray absorption fine structure (EXAFS) of the S{sub 0} state indicates that a significant structural rearrangement occurs between the S{sub 0} and S{sub 1} states.

  8. Manganese-induced turnover of TMEM165.

    PubMed

    Potelle, Sven; Dulary, Eudoxie; Climer, Leslie; Duvet, Sandrine; Morelle, Willy; Vicogne, Dorothée; Lebredonchelle, Elodie; Houdou, Marine; Spriet, Corentin; Krzewinski-Recchi, Marie-Ange; Peanne, Romain; Klein, André; DE Bettignies, Geoffroy; Morsomme, Pierre; Matthijs, Gert; Marquardt, Thorsten; Lupashin, Vladimir; Foulquier, Francois

    2017-03-07

    TMEM165 deficiencies lead to one of the Congenital Disorders of Glycosylation (CDG), a group of inherited diseases where the glycosylation process is altered. We recently demonstrated that the Golgi glycosylation defect due to TMEM165 deficiency resulted from Golgi manganese homeostasis defect and that Mn2+ supplementation was sufficient to rescue normal glycosylation. In this paper we highlight TMEM165 as a novel Golgi protein sensitive to manganese. When cells were exposed to high Mn2+ concentrations, TMEM165 was degraded in lysosomes. Remarkably, while the variant R126H was sensitive upon manganese exposure, the variant E108G recently identified in a novel TMEM165-CDG patient, was found to be insensitive. We also showed that the E108G mutation did not abolish the function of TMEM165 in Golgi glycosylation. Altogether this study identified the Golgi protein TMEM165 as a novel Mn2+ sensitive protein in mammalian cells and pointed to the crucial importance of the glutamic acid (E108) in the cytosolic ELGDK motif in Mn2+ induced degradation of TMEM165.

  9. Characterization and Prediction of Flow Behavior in High-Manganese Twinning Induced Plasticity Steels: Part II. Jerky Flow and Instantaneous Strain Rate

    NASA Astrophysics Data System (ADS)

    Saeed-Akbari, A.; Mishra, A. K.; Mayer, J.; Bleck, W.

    2012-05-01

    The jerky and smooth flow curves in high-manganese twinning induced plasticity (TWIP) steels were investigated by comparing Fe-Mn-C and Fe-Mn-Al-C systems. The pronounced serrations on the flow curves of Fe-Mn-C TWIP steel, produced during tensile testing at 300 K (27 °C) and 373 K (100 °C), were shown to be the result of localized high-temperature Portevin Le-Chatelier (PLC) bands moving across the gage length throughout the deformation. The speed of the PLC bands and their temperature effects were found to be strongly dependent on the applied strain rate, which was controlled by adjusting the cross-head speed of the tensile testing machine. The localized temperature-dependent stacking fault energy (SFE) variations resulting from the PLC effect and adiabatic heating were analyzed and compared for both slow and fast deformation rates. The instabilities in the measured logarithmic strain values caused by jerky flow could cause the local strain rate to deviate systematically from the targeted (applied) strain rate. These instabilities are better observed by calculating the instantaneous strain rate (ISR) values for each instant of deformation along the entire gage length. Finally, a new type of diagram was developed by plotting the true stress against the ISR values. From the diagram, the onset of different mechanisms, such as deformation twinning, nonpronounced, and pronounced serrations, could be marked precisely.

  10. Mechanism of site-specific DNA damage induced by methylhydrazines in the presence of copper(II) or manganese(III)

    SciTech Connect

    Kawanishi, Shosuke; Yamamoto, Koji )

    1991-03-26

    DNA damage induced by methylhydrazines in the presence of metal ions was investigated by a DNA sequencing technique. 1,2-Dimethylhydrazine plus Mn(III) caused DNA cleavage at every nucleotide without marked site specificity. ESR-spin-trapping experiments showed that the hydroxyl free radical ({center dot}OH) is generated during the Mn(III)-catalyzed autoxidation of 1,2-dimethylhydrazine. DNA damage and {center dot}OH generation were inhibited by {center dot}OH scavengers and superoxide dismutase, but not by catalase. The results suggest that 1,2-dimethylhydrazine plus Mn(III) generates {center dot}OH, not via H{sub 2}O{sub 2}, and that {center dot}OH causes DNA damage. In the presence of Cu(II), DNA cleavage was caused by the three methylhydrazines frequently at thymine residues, especially of the GTC sequence. Catalase and bathocuproine, a Cu(I)-specific chelating agent, inhibited DNA damage while catalase did not inhibit the {center dot}CH{sub 3} generation. The order of DNA damage was correlated with the order of ratio of H{sub 2}O{sub 2} production to O{sub 2} consumption observed during Cu(II)-catalyzed autooxidation of methylhydrazines. These results suggest that the Cu(I)-peroxide complex rather than the {center dot}CH{sub 3} plays a more important role in methylhydrazine plus Cu(II)-induced DNA damage.

  11. Manganese

    SciTech Connect

    Major-Sosias, M.A.

    1996-10-01

    Manganese (Mn) is a hard, brittle, gray-white transition metal, with the most numerous oxidation states of the elements in the first series of the Periodic Table. Since the manganese atom can donate up to seven electrons from its outer two shells, manganese compounds exist with valences from -3 to +7, the most common being +2, +4, and +7. Due to its sulfur-fixing, deoxidizing, and alloying properties, as well as its low cost, the principal commercial application for manganese is in iron and steel production. Manganese is also employed in non-ferrous metallurgy, batteries and chemical processes. Although potentially harmful to the respiratory and nervous systems, manganese is an essential element for animals and humans, and a micronutrient for plants.

  12. Genetic factors and manganese-induced neurotoxicity

    PubMed Central

    Chen, Pan; Parmalee, Nancy; Aschner, Michael

    2014-01-01

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

  13. Potential Role of Epigenetic Mechanism in Manganese Induced Neurotoxicity

    PubMed Central

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

    2016-01-01

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

  14. Potential Role of Epigenetic Mechanism in Manganese Induced Neurotoxicity.

    PubMed

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

    2016-01-01

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

  15. Oxidation kinetics of manganese (II) in seawater at nanomolar concentrations

    NASA Astrophysics Data System (ADS)

    von Langen, Peter J.; Johnson, Kenneth S.; Coale, Kenneth H.; Elrod, Virginia A.

    1997-12-01

    Manganese oxidation rates were determined at low (˜ 20 nM) concentrations in seawater by measuring dissolved manganese (Mn(II)) using flow injection analysis with chemiluminescence detection. Mn(II) was measured in samples that had been filtered (0.2 μm) and kept in the dark under controlled temperature and pH conditions for time periods up to 6 months. Eight 9 L carboys with mean pH values ranging from 8 to 8.7 were held at 25°C, another carboy (pH = 9.32) was kept at 5°C. Oxidation followed the Morgan (1967) homogeneous rate equation ( d[Mn(II)]/ dt = k1 [O 2][OH -] 2[Mn(II)]). The mean rate constant k1 = 1.7 ± 0.7 × 10 12 M -3 d -1 (95% CI), determined using hydroxide ion activities determined with pH measurements on the NBS scale, was in agreement with work by Morgan (1967; k1 = 4 × 10 12 M -3 d -1) and Davies and Morgan (1989; k1 = 1.1 × 10 12 M -3 d -1) in dilute solutions. The rate constant at 5°C was 1.3 ± 0.3 × 10 12 M -3 d -1. If free hydroxide concentrations (based on the free proton pH scale) are used, then the rate constant at 25°C was k 1∗ = 0.34 ± 0.14 × 10 12 M -3d -1. Autocatalytic increases in Mn(II) oxidation rates, as predicted by a heterogeneous reaction mechanism (Morgan, 1967) ( d[Mn(II)]/ dt= k2'[Mn(II)][MnO 2]) were not observed, indicating that the homogeneous reaction dominates Mn(II) oxidation at low nM concentrations in seawater. Bacteria were enumerated by 4',6-diamidino-2-phenylindole (DAPI) staining during the experiments. No significant correlation between bacterial concentrations and Mn(II) oxidation rates was found.

  16. Temperature Dependence of Light-Induced Absorbance Changes Associated with Chlorophyll Photooxidation in Manganese-Depleted Core Complexes of Photosystem II.

    PubMed

    Zabelin, A A; Shkuropatova, V A; Shkuropatov, A Ya; Shuvalov, V A

    2015-10-01

    Mid-infrared (4500-1150 cm(-1)) absorbance changes induced by continuous illumination of Mn-depleted core complexes of photosystem II (PSII) from spinach in the presence of exogenous electron acceptors (potassium ferricyanide and silicomolybdate) were studied by FTIR difference spectroscopy in the temperature range 100-265 K. The FTIR difference spectrum for photooxidation of the chlorophyll dimer P680 was determined from the set of signals associated with oxidation of secondary electron donors (β-carotene, chlorophyll) and reduction of the primary quinone QA. On the basis of analysis of the temperature dependence of the P680(+)/P680 FTIR spectrum, it was concluded that frequencies of 13(1)-keto-C=O stretching modes of neutral chlorophyll molecules PD1 and PD2, which constitute P680, are similar to each other, being located at ~1700 cm(-1). This together with considerable difference between the stretching mode frequencies of keto groups of PD1(+) and PD2(+) cations (1724 and 1709 cm(-1), respectively) is in agreement with a literature model (Okubo et al. (2007) Biochemistry, 46, 4390-4397) suggesting that the positive charge in the P680(+) dimer is mainly localized on one of the two chlorophyll molecules. A partial delocalization of the charge between the PD1 and PD2 molecules in P680(+) is supported by the presence of a characteristic electronic intervalence band at ~3000 cm(-1). It is shown that a bleaching band at 1680 cm(-1) in the P680(+)/P680 FTIR spectrum does not belong to P680. A possible origin of this band is discussed, taking into account the temperature dependence (100-265 K) of light-induced absorbance changes of PSII core complexes in the visible spectral region from 620 to 720 nm.

  17. Hydrolytic cleavage of DNA by quercetin manganese(II) complexes.

    PubMed

    Jun, Tan; Bochu, Wang; Liancai, Zhu

    2007-04-01

    Quercetin manganese(II) complexes were investigated focusing on its DNA hydrolytic activity. The complexes successfully promote the cleavage of plasmid DNA, producing single and double DNA strand breaks. The amount of conversion of supercoiled form (SC) of plasmid DNA to the nicked circular form (NC) depends on the concentration of the complex as well as the duration of incubation of the complexes with DNA. The maximum rate of conversion of the supercoiled form to the nicked circular form at pH 7.2 in the presence of 100 microM of the complexes is found to be 1.32 x 10(-4) s(-1). The hydrolytic cleavage of DNA by the complexes was supported by the evidence from free radical quenching, thiobarbituric acid-reactive substances (TBARS) assay and T4 ligase ligation.

  18. Reduction of paraquat-induced renal cytotoxicity by manganese and copper complexes of EGTA and EHPG.

    PubMed

    Samai, Mohamed; Hague, Theresa; Naughton, Declan P; Gard, Paul R; Chatterjee, Prabal K

    2008-02-15

    Superoxide anion generation plays an important role in the development of paraquat toxicity. Although superoxide dismutase mimetics (SODm) have provided protection against organ injury involving generation of superoxide anions, they often suffer problems, e.g., regarding their bioavailability or potential pro-oxidant activity. The aim here was to investigate and compare the therapeutic potential of two novel SODm, manganese(II) and copper(II) complexes of the calcium chelator ethylenebis(oxyethylenenitrilo)tetraacetic acid (EGTA) and of the contrast agent ethylenebis(hydroxyphenylglycine) (EHPG), against paraquat-induced renal toxicity in vitro. Incubation of renal NRK-52E cells with paraquat (1 mM) for 24 h produced submaximal, yet significant, reduction in cellular viability and cell death and produced significant increases in superoxide anion and hydroxyl radical generation. Manganese and copper complexes of EGTA (10-100 microM) and EHPG (30-100 microM) reduced paraquat-induced renal cell toxicity and reduced superoxide anion and hydroxyl radical generation significantly. Manganese complexes displayed greater efficacy than copper complexes and, at equivalent concentrations, manganese complexed with EHPG provided the greatest protection. Furthermore, these metal complexes did not interfere with the uptake of [methyl-(14)C]paraquat into NRK-52E cells, suggesting that they provided protection against paraquat cytotoxicity via intracellular mechanisms. These complexes did not display cytotoxicity at the concentrations examined. Together, these results suggest that manganese and copper complexes of EGTA and EHPG, and especially the manganese-EHPG complex, could provide benefit against paraquat nephrotoxicity.

  19. Manganese

    Integrated Risk Information System (IRIS)

    Manganese ; CASRN 7439 - 96 - 5 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Effect

  20. Manganese(III) binding to a pyoverdine siderophore produced by a manganese(II)-oxidizing bacterium

    NASA Astrophysics Data System (ADS)

    Parker, Dorothy L.; Sposito, Garrison; Tebo, Bradley M.

    2004-12-01

    The possible roles of siderophores (high affinity chelators of iron(III)) in the biogeochemistry of manganese remain unknown. Here we investigate the interaction of Mn(III) with a pyoverdine-type siderophore (PVD MnB1) produced by the model Mn(II)-oxidizing bacterium Pseudomonas putida strain MnB1. PVD MnB1 confirmed typical pyoverdine behavior with respect to: (a) its absorption spectrum at 350-600 nm, both in the absence and presence of Fe(III), (b) the quenching of its fluorescence by Fe(III), (c) the formation of a 1:1 complex with Fe(III), and (d) the thermodynamic stability constant of its Fe(III) complex. The Mn(III) complex of PVD MnB1 had a 1:1 Mn:pvd molar ratio, showed fluorescence quenching, and exhibited a light absorption spectrum (A max = 408-410 nm) different from that of either PVD MnB1-Fe(III) or uncomplexed PVD MnB1. Mn(III) competed strongly with Fe(III) for binding by PVD MnB1 in culture filtrates (pH 8, 4°C). Equilibration with citrate, a metal-binding ligand, did not detectably release Mn from its PVD MnB1 complex at a citrate/PVD MnB1 molar ratio of 830 (pH 8, 4°C), whereas pyrophosphate under the same conditions removed 55% of the Mn from its PVD MnB1 complex. Most of the PVD MnB1-complexed Mn was released by reaction with ascorbate, a reducing agent, or with EDTA, a ligand that is also oxidized by Mn(III). Data on the competition for binding to PVD MnB1 by Fe(III) vs. Mn(III) were used to determine a thermodynamic stability constant (nominally at 4°C) for the neutral species MnHPVD MnB1 (log K = 47.5 ± 0.5, infinite dilution reference state). This value was larger than that determined for FeHPVD MnB1 (log K = 44.6 ± 0.5). This result has important implications for the metabolism, solubility, speciation, and redox cycling of manganese, as well as for the biologic uptake of iron.

  1. Helicity inversion and redox chemistry of chiral manganese(II) cubanes.

    PubMed

    Deville, Claire; Granelli, Matteo; Downward, Alan M; Besnard, Céline; Guenée, Laure; Williams, Alan F

    2014-09-14

    The chiral ligand S-1,2-bis(1H-benzimidazol-2-yl)ethanol, 1, reacts with manganese(II) salts to form cubanes which readily undergo oxidation reactions leading either to a tetranuclear manganese(II,III) mixed valence complex 4 or to a tetranuclear complex of ligand 5 where the secondary alcohol has been oxidised to an enolate. N-methylation of ligand 1 slows the oxidation reaction and stable manganese(II) cubanes may be isolated. The fully methylated ligand 2 gives a cubane of opposite helicity to that found previously for 1 with cobalt. The inversion may be explained by conformational analysis. Cyclic voltammetry suggests that the manganese cubanes reported here are insufficiently robust to store oxidising equivalents as in the oxygen evolving system of photosystem II.

  2. Sorption behaviour of manganese-coated calcined-starfish and manganese-coated sand for Mn(II).

    PubMed

    Lee, Seung-Mok; Kim, Won-Gee; Yang, Jae-Kyu; Tiwari, Diwakar

    2010-04-01

    The objective of the present investigation was to explore the sorption behaviour of manganese-coated samples of calcined starfish (MCCSF) (i.e. the impregnation of calcined starfish with manganese) for the removal of low levels of an important heavy metal toxic ion, Mn(II), from aqueous solutions. The suitability of this solid was further compared with two different samples of manganese-coated sands (MCS): MCS4 and MCS9 impregnated at pH 4.0 and pH 9.0, respectively. These comparative studies were performed in both batch and column experiments. Batch data indicated that a fairly good stability of the coating was obtained for these three samples in the pH region 2.5 to 10.0. The removal efficiency of MCCSF was fairly good in comparison with the MCS4 and MCS9 samples. These last two samples possessed similar Mn(II) removal capacities. Moreover, a small dose of sodium hypochlorite further enhanced the uptake of Mn(II) by these solids. The sorbate concentration dependence data fitted reasonably well to the Freundlich adsorption isotherm. The column data indicated that MCCSF possessed a relatively higher adsorption capacity compared with the MCS4 and MCS9 samples. The breakthrough curves obtained were then used to evaluate the apparent removal capacity of these solids under the dynamic conditions using the Thomas equation. The SEM images obtained for these manganese-coated solids along with the virgin base materials, i.e. sand and calcined starfish, showed that manganese oxides occupied the surfaces or pores of the base materials and formed clusters on the base surface.

  3. Calcium-manganese oxides as structural and functional models for active site in oxygen evolving complex in photosystem II: lessons from simple models.

    PubMed

    Najafpour, Mohammad Mahdi

    2011-01-01

    The oxygen evolving complex in photosystem II which induces the oxidation of water to dioxygen in plants, algae and certain bacteria contains a cluster of one calcium and four manganese ions. It serves as a model to split water by sunlight. Reports on the mechanism and structure of photosystem II provide a more detailed architecture of the oxygen evolving complex and the surrounding amino acids. One challenge in this field is the development of artificial model compounds to study oxygen evolution reaction outside the complicated environment of the enzyme. Calcium-manganese oxides as structural and functional models for the active site of photosystem II are explained and reviewed in this paper. Because of related structures of these calcium-manganese oxides and the catalytic centers of active site of the oxygen evolving complex of photosystem II, the study may help to understand more about mechanism of oxygen evolution by the oxygen evolving complex of photosystem II.

  4. Photodamage of a Mn(III/IV)-oxo mixed-valence compound and photosystem II: evidence that a high-valent manganese species is responsible for UV-induced photodamage of the oxygen-evolving complex in photosystem II.

    PubMed

    Wei, Zi; Cady, Clyde W; Brudvig, Gary W; Hou, Harvey J M

    2011-01-01

    The Mn cluster in photosystem II (PS II) is believed to play an important role in the UV photoinhibition of green plants, but the mechanism is still not clear at a molecular level. In this work, the photochemical stability of [Mn(III)(O)(2)Mn(IV)(H(2)O)(2)(Terpy)(2)](NO(3))(3) (Terpy=2,2':6',2''-terpyridine), designated as Mn-oxo mixed-valence dimer, a well characterized functional model of the oxygen-evolving complex in PS II, was examined in aqueous solution by exposing the complex to excess light irradiation at six different wavelengths in the range of 250 to 700 nm. The photodamage of the Mn-oxo mixed-valence dimer was confirmed by the decrease of its oxygen-evolution activity measured in the presence of the chemical oxidant oxone. Ultraviolet light irradiation induced a new absorption peak at around 400-440 nm of the Mn-oxo mixed-valence dimer. Visible light did not have the same effect on the Mn-oxo mixed-valence dimer. We speculate that the spectral change may be caused by conversion of the Mn(III)O(2)Mn(IV) dimer into a new structure--Mn(IV)O(2)Mn(IV). In the processes, the appearance of a 514 nm fluorescence peak was observed in the solution and may be linked to the hydration or protonation of Terpy ligand in the Mn-oxo dimer. In comparing the response of the PS II functional model compound and the PS II complex to excess light radiation, our results support the idea that UV photoinhibition is triggered at the Mn(4)Ca center of the oxygen-evolution complex in PS II by forming a modified structure, possibly a Mn(IV) species, and that the reaction of Mn ions is likely the initial step.

  5. Catalase-like activity studies of the manganese(II) adsorbed zeolites

    NASA Astrophysics Data System (ADS)

    ćiçek, Ekrem; Dede, Bülent

    2013-12-01

    Preparation of manganese(II) adsorbed on zeolite 3A, 4A, 5A. AW-300, ammonium Y zeolite, organophilic, molecular sieve and catalase-like enzyme activity of manganese(II) adsorbed zeolites are reported herein. Firstly zeolites are activated at 873 K for two hours before contact manganese(II) ions. In order to observe amount of adsorption, filtration process applied for the solution. The pure zeolites and manganese(II) adsorbed zeolites were analysed by FT-IR. As a result according to the FT-IR spectra, the incorporation of manganese(II) cation into the zeolite structure causes changes in the spectra. These changes are expected particularly in the pseudolattice bands connected with the presence of alumino and silicooxygen tetrahedral rings in the zeolite structure. Furthermore, the catalytic activities of the Mn(II) adsorbed zeolites for the disproportionation of hydrogen peroxide were investigated in the presence of imidazole. The Mn(II) adsorbed zeolites display efficiency in the disproportion reactions of hydrogen peroxide, producing water and dioxygen in catalase-like activity.

  6. Catalase-like activity studies of the manganese(II) adsorbed zeolites

    NASA Astrophysics Data System (ADS)

    Ćiçek, Ekrem; Dede, Bülent

    2013-12-01

    Preparation of manganese(II) adsorbed on zeolite 3A, 4A, 5A. AW-300, ammonium Y zeolite, organophilic, molecular sieve and catalase-like enzyme activity of manganese(II) adsorbed zeolites are reported herein. Firstly zeolites are activated at 873 K for two hours before contact manganese(II) ions. In order to observe amount of adsorption, filtration process applied for the solution. The pure zeolites and manganese(II) adsorbed zeolites were analysed by FT-IR. As a result according to the FT-IR spectra, the incorporation of manganese(II) cation into the zeolite structure causes changes in the spectra. These changes are expected particularly in the pseudolattice bands connected with the presence of alumino and silicooxygen tetrahedral rings in the zeolite structure. Furthermore, the catalytic activities of the Mn(II) adsorbed zeolites for the disproportionation of hydrogen peroxide were investigated in the presence of imidazole. The Mn(II) adsorbed zeolites display efficiency in the disproportion reactions of hydrogen peroxide, producing water and dioxygen in catalase-like activity.

  7. Manganese inhibits poly(ADP-ribosyl)ation in human cells: a possible mechanism behind manganese-induced toxicity?

    PubMed

    Bornhorst, Julia; Ebert, Franziska; Hartwig, Andrea; Michalke, Bernhard; Schwerdtle, Tanja

    2010-11-01

    For humans manganese is both an essential trace element and, at higher doses, a toxic metal. Due to the ubiquitous occurrence of manganese in foodstuff, in industrial countries daily dietary uptake is higher as compared to the estimated daily requirement. Therefore manganese deficiency is extremely rare. In contrast chronic manganese toxicity, affecting primarily the central nervous system, is more prevalent. Thus manganese occupational and dietary overexposure has been shown to cause progressive, permanent, neurodegenerative damage, resulting in syndromes similar to idiopathic Parkinson's disease. To date modes of manganese neurotoxic action are poorly understood and in most studies oxidative stress is postulated as the underlying mechanism. The present study searched on the cellular level for a molecular mechanism behind manganese-induced neurotoxicity and investigated bioavailability, cytotoxicity and genotoxicity of MnCl(2), as well as its impact on the DNA damage response in human cells (HeLa S3) in culture. Whereas up to 10 µM MnCl(2) showed no induction of DNA strand breaks after 24 h incubation, manganese strongly inhibited H(2)O(2)-stimulated poly(ADP-ribosyl)ation at low, completely non-cytotoxic, for certain human exposure, relevant concentrations starting at 1 µM. Thereby inhibition of this essential DNA damage response signalling reaction was not due to a reduced gene expression or protein level of the responsible polymerase PARP-1. Taken together, the results indicate that manganese, under conditions of either overload due to high exposure or disturbed homeostasis, can disturb the cellular response to DNA strand breaks, which has been shown before (S. Katyal and P. J. McKinnon, Mech. Ageing Dev., 2008, 129, 483-491) to result in neurological diseases.

  8. Bioelectrochemical Mn(II) leaching from manganese ore by Lactococcus lactis SK071115.

    PubMed

    Jeon, Bo Young; Park, Doo Hyun

    2011-02-01

    L. lactis sk071115 has been shown to grow more actively and generate lower levels of lactate in glucose-defined medium with nitrate than in medium with Mn(IV). By adding Mn(IV) to a L. lactis culture, lactate production was relatively reduced in combination with Mn(II) production, but cell mass production levels did not increase. Both cell-free extract and intact L. lactis cells reacted electrochemically with Mn(IV) but did not react with Mn(II) upon cyclic voltammetry using neutral red (NR) as an electron mediator. A modified graphite felt cathode with NR (NR-cathode) was employed to induce electrochemical reducing equivalence for bacterial metabolism. Cell-free L. lactis extract catalyzed the reduction of Mn(IV) to Mn(II) under both control and electrochemical reduction conditions; however, the levels of Mn(II) generated under electrochemical reduction conditions were approximately 4 times those generated under control conditions. The levels of Mn(II) generated by the catalysis of L. lactis immobilized in the NR-cathode (L-NR-cathode) under electrochemical reduction conditions were more than 4 times that generated under control conditions. Mn(II) production levels were increased by approximately 2.5 and 4.5 times by the addition of citrate to the reactant under control and electrochemical reduction conditions, respectively. The cumulative Mn(II) produced from manganese ore by catalysis of the L-NR-cathode for 30 days reached levels of approximately 3,800 and 16,000 mg/l under control and electrochemical reduction conditions, respectively. In conclusion, the electrochemical reduction reaction generated by the NR-cathode activated the biochemical reduction of Mn(IV) to Mn(II) by L. lactis.

  9. Manganese(II) semiquinonato and manganese(III) catecholato complexes with tridentate ligand: modeling the substrate-binding state of manganese-dependent catechol dioxygenase and reactivity with molecular oxygen.

    PubMed

    Komatsuzaki, Hidehito; Shiota, Akihiko; Hazawa, Shogo; Itoh, Muneaki; Miyamura, Noriko; Miki, Nahomi; Takano, Yoichi; Nakazawa, Jun; Inagaki, Akiko; Akita, Munetaka; Hikichi, Shiro

    2013-06-01

    Catecholate catwalk: Monomeric manganese(III) catecholato and manganese(II) semiquinonato complexes as the substrate-binding model of catechol dioxygenase have been synthesized and structurally characterized. The semiquinonato complex reacted with molecular oxygen to give ring-cleaved products and benzoquinone in the catalytic condition.

  10. The laboratory methods of induced polarization measurement of manganese sample

    NASA Astrophysics Data System (ADS)

    Adhiguna, D.; Handayani, G.

    2015-09-01

    Metallic minerals are polarizable. The polarizable property can be used as the basis for metallic minerals exploration process. By use of induced polarization method, we observed polarization phenomenon that occur in metallic material. In this study, physical events were observed that occur in rocks containing manganese minerals using induced polarization method. Induced polarization method is a geophysical method that is based on the principle of electrical charging and discharging of a capacitor which is applied to the rock. By using the method of induced polarization, chargeability values can be determined for the rock. Chargeability is one of the important properties of metal material. Measurement on this research will be done in two different ways to determine the induced events that occurred in both methods.

  11. Manganese(II) Chloride Alters Nucleotide and Nucleoside Catabolism in Zebrafish (Danio rerio) Adult Brain.

    PubMed

    Altenhofen, Stefani; Nabinger, Débora Dreher; Pereira, Talita Carneiro Brandão; Leite, Carlos Eduardo; Bogo, Maurício Reis; Bonan, Carla Denise

    2017-05-25

    ATP and adenosine, the main signaling molecules of purinergic system, are involved in toxicological effects induced by metals. The manganese (Mn) exposure induces several cellular changes, which could interfere with signaling pathways, such as the purinergic system. In this study, we evaluated the effects of exposure to manganese(II) chloride (MnCl2) during 96 h on nucleoside triphosphate diphosphohydrolase (NTPDase), ecto-5'-nucleotidase, and adenosine deaminase (ADA) activities, followed by analyzing the gene expression patterns of NTPDases (entpd1, entpd2a.1, entpd2a.2, entpd2-like, entpd3) and ADA (ADA 1 , ADA 2.1 , ADA 2.2 , ADAasi, ADAL) families in zebrafish brain. In addition, the brain metabolism of nucleotides and nucleosides was evaluated after MnCl2 exposure. The results showed that MnCl2 exposure during 96 h inhibited the NTPDase (1.0 and 1.5 mM) and ecto-ADA (0.5, 1.0, and 1.5 mM) activities, further decreasing ADA2.1 expression at all MnCl2 concentrations analyzed. Purine metabolism was also altered by the action of MnCl2. An increased amount of ADP appeared at all MnCl2 concentrations analyzed; however, AMP and adenosine levels are decreased at the concentrations of 1.0 and 1.5 mM MnCl2, whereas decreased inosine (INO) levels were observed at all concentrations tested. The findings of this study demonstrated that MnCl2 may inhibit NTPDase and ecto-ADA activities, consequently modulating nucleotide and nucleoside levels, which may contribute for the toxicological effects induced by this metal.

  12. Electrochemical Behavior and Voltammetric Determination of a Manganese(II) Complex at a Carbon Paste Electrode

    PubMed Central

    Karastogianni, Sophia; Girousi, Stella

    2016-01-01

    Investigation of the electrochemical behavior using cyclic voltammetry and detection of [Mn2+(thiophenyl-2-carboxylic acid)2 (triethanolamine)] with adsorptive stripping differential pulse voltammetry. The electrochemical behavior of a manganese(II) complex [Mn2+(thiophenyl-2-carboxylic acid)2(triethanolamine)] (A) was investigated using cyclic and differential pulse voltammetry in an acetate buffer of pH 4.6 at a carbon paste electrode. Further, an oxidation–reduction mechanism was proposed. Meanwhile, an adsorptive stripping differential pulse voltammetric method was developed for the determination of manganese(II) complex. PMID:26819548

  13. Electrochemical Behavior and Voltammetric Determination of a Manganese(II) Complex at a Carbon Paste Electrode.

    PubMed

    Karastogianni, Sophia; Girousi, Stella

    2016-01-01

    Investigation of the electrochemical behavior using cyclic voltammetry and detection of [Mn(2+)(thiophenyl-2-carboxylic acid)2 (triethanolamine)] with adsorptive stripping differential pulse voltammetry. The electrochemical behavior of a manganese(II) complex [Mn(2+)(thiophenyl-2-carboxylic acid)2(triethanolamine)] (A) was investigated using cyclic and differential pulse voltammetry in an acetate buffer of pH 4.6 at a carbon paste electrode. Further, an oxidation-reduction mechanism was proposed. Meanwhile, an adsorptive stripping differential pulse voltammetric method was developed for the determination of manganese(II) complex.

  14. Polydisulfide Manganese(II) Complexes as Non-Gadolinium Biodegradable Macromolecular MRI Contrast Agents

    PubMed Central

    Ye, Zhen; Jeong, Eun-Kee; Wu, Xueming; Tan, Mingqian; Yin, Shouyu; Lu, Zheng-Rong

    2011-01-01

    Purpose To develop safe and effective manganese(II) based biodegradable macromolecular MRI contrast agents. Materials and Methods In this study, we synthesized and characterized two polydisulfide manganese(II) complexes, Mn-DTPA cystamine copolymers and Mn-EDTA cystamine copolymers, as new biodegradable macromolecular MRI contrast agents. The contrast enhancement of the two manganese based contrast agents were evaluated in mice bearing MDA-MB-231 human breast carcinoma xenografts, in comparison with MnCl2. Results The T1 and T2 relaxivities were 4.74 and 10.38 mM−1s−1 per manganese at 3T for Mn-DTPA cystamine copolymers (Mn=30.50 kDa) and 6.41 and 9.72 mM−1s−1 for Mn-EDTA cystamine copolymers (Mn= 61.80 kDa). Both polydisulfide Mn(II) complexes showed significant liver, myocardium and tumor enhancement. Conclusion The manganese based polydisulfide contrast agents have a potential to be developed as alternative non-gadolinium contrast agents for MR cancer and myocardium imaging. PMID:22031457

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

    PubMed Central

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

    2014-01-01

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

  16. Speciation of dissolved iron(II) and manganese(II) in a groundwater pollution plume

    SciTech Connect

    Jensen, D.L.; Boddum, J.K.; Redemann, S.; Christensen, T.H.

    1998-09-15

    Groundwater samples with high concentrations of Fe(II) and Mn(II), obtained from an anaerobic pollution plume, were speciated under anaerobic conditions in terms of colloidal (screen filtration and cross-flow ultrafiltration), complexed (ion-exchange resins), and free divalent species of Fe(II) and Mn(II). Most of the metal content in a nonfiltered sample passed through a 0.001 {micro}m membrane and was considered truly dissolved. Although free metal ions were the dominant species in the dissolved fraction, speciation modeling using MINTEQA2 suggested an average of 19% Fe(II) a/nd 20% Mn(II) were present as bicarbonate complexes, which are here operationally defined as labile. Organic complexes were not significant, although the groundwater contained up to 67 mg of C L{sup {minus}1}. Calculations with MINTEQA2 indicated that sample solutions representative of the truly dissolved fraction were strongly supersaturated with respect to siderite (FeCO{sub 3}) and moderately supersaturated with respect to rhodochrosite (MnCO{sub 3}). SEM-EDS (Scanning Electron Microscopy combined with Energy Dispersive X-ray Spectroscopy) analysis indicated that the colloidal fractions most likely consisted of clay type particles and iron sulfide precipitates. The amount of Mn(II) in the colloidal fractions was too low for determination by SEM-EDS. These results show that roughly 65% of the iron and manganese in anaerobic pollution plumes is present as free divalent ions and, according to the current thermodynamic database in MINTEQA2, the solutions are supersaturated with respect to carbonate.

  17. Cobalt(II) Oxidation by the Marine Manganese(II)-Oxidizing Bacillus sp. Strain SG-1

    PubMed Central

    Lee, Yoon; Tebo, Bradley M.

    1994-01-01

    The geochemical cycling of cobalt (Co) has often been considered to be controlled by the scavenging and oxidation of Co(II) on the surface of manganese [Mn(III,IV)] oxides or manganates. Because Mn(II) oxidation in the environment is often catalyzed by bacteria, we have investigated the ability of Mn(II)-oxidizing bacteria to bind and oxidize Co(II) in the absence of Mn(II) to determine whether some Mn(II)-oxidizing bacteria also oxidize Co(II) independently of Mn oxidation. We used the marine Bacillus sp. strain SG-1, which produces mature spores that oxidize Mn(II), apparently due to a protein in their spore coats (R.A. Rosson and K. H. Nealson, J. Bacteriol. 151:1027-1034, 1982; J. P. M. de Vrind et al., Appl. Environ. Microbiol. 52:1096-1100, 1986). A method to measure Co(II) oxidation using radioactive 57Co as a tracer and treatments with nonradioactive (cold) Co(II) and ascorbate to discriminate bound Co from oxidized Co was developed. SG-1 spores were found to oxidize Co(II) over a wide range of pH, temperature, and Co(II) concentration. Leucoberbelin blue, a reagent that reacts with Mn(III,IV) oxides forming a blue color, was found to also react with Co(III) oxides and was used to verify the presence of oxidized Co in the absence of added Mn(II). Co(II) oxidation occurred optimally around pH 8 and between 55 and 65°C. SG-1 spores oxidized Co(II) at all Co(II) concentrations tested from the trace levels found in seawater to 100 mM. Co(II) oxidation was found to follow Michaelis-Menten kinetics. An Eadie-Hofstee plot of the data suggests that SG-1 spores have two oxidation systems, a high-affinity-low-rate system (Km, 3.3 × 10-8 M; Vmax, 1.7 × 10-15 M · spore-1 · h-1) and a low-affinity-high-rate system (Km, 5.2 × 10-6 M; Vmax, 8.9 × 10-15 M · spore-1 · h-1). SG-1 spores did not oxidize Co(II) in the absence of oxygen, also indicating that oxidation was not due to abiological Co(II) oxidation on the surface of preformed Mn(III,IV) oxides. These

  18. Mechanisms of manganese-induced neurotoxicity in primary neuronal cultures: the role of manganese speciation and cell type.

    PubMed

    Hernández, R B; Farina, M; Espósito, B P; Souza-Pinto, N C; Barbosa, F; Suñol, C

    2011-12-01

    Manganese (Mn) is an essential trace element required for the proper functioning of a variety of physiological processes. However, chronic exposures to Mn can cause neurotoxicity in humans, especially when it occurs during critical stages of the central nervous system development. The mechanisms mediating this phenomenon as well as the contribution of Mn speciation and the sensitivity of different types of neuronal cells in such toxicity are poorly understood. This study was aimed to investigate the mechanisms mediating the toxic effects of MnCl(2), Mn(II) citrate, Mn(III) citrate, and Mn(III) pyrophosphate in primary cultures of neocortical (CTX) and cerebellar granular (CGC) neurons. Cell viability, mitochondrial function, and glutathione levels were evaluated after Mn exposure. CGC were significantly more susceptible to Mn-induced toxicity when compared with CTX. Moreover, undifferentiated CGC were more vulnerable to Mn toxicity than mature neurons. Mitochondrial dysfunction was observed after the exposure to all the tested Mn species. Ascorbate protected CGC against Mn-induced neurotoxicity, and this event seemed to be related to the dual role of ascorbate in neurons, acting as antioxidant and metabolic energetic supplier. CTX were protected from Mn-induced toxicity by ascorbate only when coincubated with lactate. These findings reinforce and extend the notion of the hazardous effects of Mn toward neuronal cells. In addition, the present results indicate that Mn-induced neurotoxicity is influenced by brain cell types, their origins, and developmental stages as well as by the chemical speciation of Mn, thus providing important information about Mn-induced developmental neurotoxicity and its risk assessment.

  19. Two different anionic manganese(II) coordination polymers constructed through dicyanamide coordination bridges.

    PubMed

    Wang, Hui Ting

    2015-10-01

    In order to explore new metal coordination polymers and to search for new types of ferroelectrics among hybrid coordination polymers, two manganese dicyanamide complexes, poly[tetramethylammonium [di-μ3-dicyanamido-κ(6)N(1):N(3):N(5)-tri-μ2-dicyanamido-κ(6)N(1):N(5)-dimanganese(II)

  20. Influence of calcium(II) and chloride on the oxidative reactivity of a manganese(II) complex of a cross-bridged cyclen ligand.

    PubMed

    Zhang, Zhan; Coats, Katherine L; Chen, Zhuqi; Hubin, Timothy J; Yin, Guochuan

    2014-11-17

    Available data from different laboratories have confirmed that both Ca(2+) and Cl(-) are crucial for water oxidation in Photosystem II. However, their roles are still elusive. Using a manganese(II) complex having a cross-bridged cyclen ligand as a model, the influence of Ca(2+) on the oxidative reactivity of the manganese(II) complex and its corresponding manganese(IV) analogue were investigated. It has been found that adding Ca(2+) can significantly improve the oxygenation efficiency of the manganese(II) complex in sulfide oxidation and further accelerate the oxidation of sulfoxide to sulfone. Similar improvements have also been observed for Mg(2+), Sr(2+), and Ba(2+). A new monomeric manganese(IV) complex having two cis-hydroxide ligands has also been isolated through oxidation of the corresponding manganese(II) complex with H2O2 in the presence of NH4PF6. This rare cis-dihydroxomanganese(IV) species has been well characterized by X-ray crystallography, electrochemistry, electron paramagnetic resonance, and UV-vis spectroscopy. Notably, using the manganese(IV) complex as a catalyst demonstrates higher activity than the corresponding manganese(II) complex, and adding Ca(2+) further improves its catalytic efficiency. However, adding Cl(-) decreases its catalytic activity. In electrochemical studies of manganese(IV) complexes with no chloride ligand present, adding Ca(2+) positively shifted the redox potential of the Mn(IV)/Mn(III) couple but negatively shifted its Mn(V)/Mn(IV) couple. In the manganese(II) complex having a chloride ligand, adding Ca(2+) shifted both the Mn(IV)/Mn(III) and Mn(V)/Mn(IV) couples in the negative direction. The revealed oxidative reactivity and redox properties of the manganese species affected by Ca(2+) and Cl(-) may provide new clues to understanding their roles in the water oxidation process of Photosystem II.

  1. Oxidation of manganese(II) with ferrate: Stoichiometry, kinetics, products and impact of organic carbon.

    PubMed

    Goodwill, Joseph E; Mai, Xuyen; Jiang, Yanjun; Reckhow, David A; Tobiason, John E

    2016-09-01

    Manganese is a contaminant of concern for many drinking water utilities, and future regulation may be pending. An analysis of soluble manganese (Mn(II)) oxidation by ferrate (Fe(VI)) was executed at the bench-scale, in a laboratory matrix, both with and without the presence of natural organic matter (NOM) and at two different pH values, 6.2 and 7.5. In the matrix without NOM, the oxidation of Mn(II) by Fe(VI) followed a stoichiometry of 2 mol Fe(VI) to 3 mol Mn(II). The presence of NOM did not significantly affect the stoichiometry of the oxidation reaction, indicating relative selectivity of Fe(VI) for Mn(II). The size distribution of resulting particles included significant amounts of nanoparticles. Resulting manganese oxide particles were confirmed to be MnO2 via X-ray photoelectron spectroscopy. The rate of the Mn(II) oxidation reaction was fast relative to typical time scales in drinking water treatment, with an estimated second order rate constant of approximately 1 × 10(4) M(-1) s(-1) at pH 9.2 and > 9 × 10(4) M(-1) s(-1) at pH 6.2. In general, ferrate is a potential option for Mn(II) oxidation in water treatment.

  2. Manganese-induced trafficking and turnover of TMEM165

    PubMed Central

    Potelle, Sven; Dulary, Eudoxie; Duvet, Sandrine; Morelle, Willy; Vicogne, Dorothée; Spriet, Corentin; Krzewinski-Recchi, Marie-Ange; Marquardt, Thorsten; deBettignies, Geoffroy; Matthijs, Gert; Lupashin, Vladimir; Foulquier, François

    2017-01-01

    TMEM165 deficiencies lead to one of the Congenital Disorders of Glycosylation (CDG), a group of inherited diseases where the glycosylation process is altered. We recently demonstrated that the Golgi glycosylation defect due to TMEM165 deficiency resulted from Golgi manganese homeostasis defect and that Mn2+ supplementation was sufficient to rescue a normal glycosylation. In this paper we highlight TMEM165 as a novel Golgi protein sensitive to manganese. When cells were exposed to high Mn2+ concentrations, TMEM165 was degraded into lysosomes. The Mn2+ induced lysosomal targeting of TMEM165 occurred via a Rab7 and Rab5 independent pathways, suggesting a direct trafficking from the Golgi to lysosomes in response to Mn2+. Remarkably, the variant p.E108G recently identified in a novel TMEM165-CDG patient, was found insensitive to Mn2+ supplementation. Moreover, this mutation abolished the function of TMEM165, suggesting that a transport function may be necessary for its regulation. Altogether our results identified the Golgi protein TMEM165 as a novel cytosolic Mn2+ sensor in mammalian cells and pointed to the crucial importance of the cytosolical ELGDK motif in both Mn2+ sensitivity and function. PMID:28270545

  3. Manganese (II) Chelate Functionalized Copper Sulfide Nanoparticles for Efficient Magnetic Resonance/Photoacoustic Dual-Modal Imaging Guided Photothermal Therapy.

    PubMed

    Liu, Renfa; Jing, Lijia; Peng, Dong; Li, Yong; Tian, Jie; Dai, Zhifei

    2015-01-01

    The integration of diagnostic and therapeutic functionalities into one nanoplatform shows great promise in cancer therapy. In this research, manganese (II) chelate functionalized copper sulfide nanoparticles were successfully prepared using a facile hydrothermal method. The obtained ultrasmall nanoparticles exhibit excellent photothermal effect and photoaoustic activity. Besides, the high loading content of Mn(II) chelates makes the nanoparticles attractive T1 contrast agent in magnetic resonance imaging (MRI). In vivo photoacoustic imaging (PAI) results showed that the nanoparticles could be efficiently accumulated in tumor site in 24 h after systematic administration, which was further validated by MRI tests. The subsequent photothermal therapy of cancer in vivo was achieved without inducing any observed side effects. Therefore, the copper sulfide nanoparticles functionalized with Mn(II) chelate hold great promise as a theranostic nanomedicine for MR/PA dual-modal imaging guided photothermal therapy of cancer.

  4. Manganese (II) Chelate Functionalized Copper Sulfide Nanoparticles for Efficient Magnetic Resonance/Photoacoustic Dual-Modal Imaging Guided Photothermal Therapy

    PubMed Central

    Liu, Renfa; Jing, Lijia; Peng, Dong; Li, Yong; Tian, Jie; Dai, Zhifei

    2015-01-01

    The integration of diagnostic and therapeutic functionalities into one nanoplatform shows great promise in cancer therapy. In this research, manganese (II) chelate functionalized copper sulfide nanoparticles were successfully prepared using a facile hydrothermal method. The obtained ultrasmall nanoparticles exhibit excellent photothermal effect and photoaoustic activity. Besides, the high loading content of Mn(II) chelates makes the nanoparticles attractive T1 contrast agent in magnetic resonance imaging (MRI). In vivo photoacoustic imaging (PAI) results showed that the nanoparticles could be efficiently accumulated in tumor site in 24 h after systematic administration, which was further validated by MRI tests. The subsequent photothermal therapy of cancer in vivo was achieved without inducing any observed side effects. Therefore, the copper sulfide nanoparticles functionalized with Mn(II) chelate hold great promise as a theranostic nanomedicine for MR/PA dual-modal imaging guided photothermal therapy of cancer. PMID:26284144

  5. Manganese induced apoptosis in haematopoietic cells of Nephrops norvegicus (L.).

    PubMed

    Oweson, Carolina A M; Baden, Susanne P; Hernroth, Bodil E

    2006-05-10

    Manganese (Mn) is highly abundant as MnO2 in marine sediments. During hypoxia in bottom waters, the reduced bioavailable fraction of manganese, Mn2+, increases. Thereby, Norway lobster, Nephrops norvegicus, can experience concentrations up to 1000 times normoxic levels. A previous study has shown that exposure to a realistic concentration of 20 mg l(-1) of Mn for 10 days reduced the number of circulating haemocytes in N. norvegicus significantly. Here we aimed to investigate if apoptosis contributes to the Mn-induced haemocytopenia, with the overall hypothesis that Mn induces apoptosis in a time and concentration dependent manner. N. norvegicus were exposed to Mn (0, 5, 10 and 20 mg l(-1)) for 5 and 10 days. After 5 days of exposure the total haemocyte counts were not affected. However, after 10 days there was a gradual decrease in cell numbers, reaching a reduction by 44% when the animals were exposed to 20 mg Mn l(-1). Apoptosis in cells, released from the haematopoietic tissue, was investigated by using TUNEL assay, which detects specific DNA strand breaks. The fraction of apoptotic cells gradually increased from 2.5% in un-exposed lobsters to 15% in those exposed to 20 mg l(-1) but there was no difference related to the exposure time. A gradual increase of apoptosis was further confirmed by electrophoretic DNA-ladder formation, however to a lower extent in lobsters exposed during 5 days. Cell viability, determined by metabolic activity and cell membrane integrity, was not reduced, indicating that apoptosis rather than necrosis caused reduced number of haemocytes. It was concluded that apoptosis seemed to increase already after 5 days of 5 mg l(-1) of Mn-exposure, although exposure for 10 days was required before it was reflected in the haemocyte numbers. Reduced numbers of haemocytes may increase the prevalence for infections in N. norvegicus in their natural habitat.

  6. Triggering autophagic cell death with a di-manganese(II) developmental therapeutic.

    PubMed

    Slator, Creina; Molphy, Zara; McKee, Vickie; Kellett, Andrew

    2017-02-04

    There is an unmet need for novel metal-based chemotherapeutics with alternative modes of action compared to clinical agents such as cisplatin and metallo-bleomycin. Recent attention in this field has focused on designing intracellular ROS-mediators as powerful cytotoxins of human cancers and identifying potentially unique toxic mechanisms underpinning their utility. Herein, we report the developmental di-manganese(II) therapeutic [Mn2(μ-oda)(phen)4(H2O)2][Mn2(μ-oda)(phen)4(oda)2]·4H2O (Mn-Oda) induces autophagy-promoted apoptosis in human ovarian cancer cells (SKOV3). The complex was initially identified to intercalate DNA by topoisomerase I unwinding and circular dichroism spectroscopy. Intracellular DNA damage, detected by γH2AX and the COMET assay, however, is not linked to direct Mn-Oda free radical generation, but is instead mediated through the promotion of intracellular reactive oxygen species (ROS) leading to autophagic vacuole formation and downstream nuclear degradation. To elucidate the cytotoxic profile of Mn-Oda, a wide range of biomarkers specific to apoptosis and autophagy including caspase release, mitochondrial membrane integrity, fluorogenic probe localisation, and cell cycle analysis were employed. Through these techniques, the activity of Mn-Oda was compared directly to i.) the pro-apoptotic clinical anticancer drug doxorubicin, ii.) the multimodal histone deacetylase inhibitor suberoyanilide hydroxamic acid, and iii.) the autophagy inducer rapamycin. In conjunction with ROS-specific trapping agents and established inhibitors of autophagy, we have identified autophagy-induction linked to mitochondrial superoxide production, with confocal image analysis of SKOV3 cells further supporting autophagosome formation.

  7. Manganese(III)-containing Wells-Dawson sandwich-type polyoxometalates: comparison with their manganese(II) counterparts.

    PubMed

    Lebrini, Mounim; Mbomekallé, Israël M; Dolbecq, Anne; Marrot, Jérôme; Berthet, Patrick; Ntienoue, Joseline; Sécheresse, Francis; Vigneron, Jacky; Etcheberry, Arnaud

    2011-07-18

    We present the synthesis and structural characterization, assessed by various techniques (FTIR, TGA, UV-vis, elemental analysis, single-crystal X-ray diffraction for three compounds, magnetic susceptibility, and electrochemistry) of five manganese-containing Wells-Dawson sandwich-type (WDST) complexes. The dimanganese(II)-containing complex, [Na(2)(H(2)O)(2)Mn(II)(2)(As(2)W(15)O(56))(2)](18-) (1), was obtained by reaction of MnCl(2) with 1 equiv of [As(2)W(15)O(56)](12-) in acetate medium (pH 4.7). Oxidation of 1 by Na(2)S(2)O(8) in aqueous solution led to the dimanganese(III) complex [Na(2)(H(2)O)(2)Mn(III)(2)(As(2)W(15)O(56))(2)](16-) (2), while its trimanganese(II) homologue, [Na(H(2)O)(2)Mn(II)(H(2)O)Mn(II)(2)(As(2)W(15)O(56))(2)](17-) (3), was obtained by addition of ca. 1 equiv of MnCl(2) to a solution of 1 in 1 M NaCl. The trimanganese(III) and tetramanganese(III) counterparts, [Mn(III)(H(2)O)Mn(III)(2)(As(2)W(15)O(56))(2)](15-) (4) and [Mn(III)(2)(H(2)O)(2)Mn(III)(2)(As(2)W(15)O(56))(2)](12-) (6), are, respectively, obtained by oxidation of aqueous solutions of 3 and [Mn(II)(2)(H(2)O)(2)Mn(II)(2)(As(2)W(15)O(56))(2)](16-) (5) by Na(2)S(2)O(8). Single-crystal X-ray analyses were carried out on 2, 3, and 4. BVS calculations and XPS confirmed that the oxidation state of Mn centers is +II for complexes 1, 3, and 5 and +III for 2, 4, and 6. A complete comparative electrochemical study was carried out on the six compounds cited above, and it was possible to observe the distinct redox steps Mn(IV/III) and Mn(III/II). Magnetization measurements, as a function of temperature, confirm the presence of antiferromagnetic interactions between the Mn ions in these compounds in all cases with the exception of compound 2.

  8. Synthesis, characterization and chemical properties of 1-((E)-2-pyridinylmethylidene)semicarbazone manganese(II) and iron(II) complexes

    NASA Astrophysics Data System (ADS)

    Garbelini, Ellery Regina; Martin, Maria da Graça M. B.; Back, Davi Fernando; Evans, David John; Müller-Santos, Marcelo; Ribeiro, Ronny Rocha; Lang, Ernesto Schulz; Nunes, Fábio Souza

    2012-01-01

    Manganese(II) perchlorate and iron(II) chloride react with 2-formylpyridine semicarbazone (HCSpy) in boiling ethanol to produce [Mn II(HSCpy) 2](ClO 4) 2·C 2H 5OH and [Fe IICl(HSCpy)]Cl. The distorted octahedral manganese complex crystallizes in the triclinic system with space group P(-1). The ligand HSCpy is tridentate and is coordinated through two nitrogen and one oxygen atoms. Comparison of the bond distances with analogous transition metal complexes that have the same geometry revealed longer bonds for the manganese derivative, an outcome that correlates well with the radius of the metal ions. The iron(II) ion is tetracoordinated to one semicarbazone and one chloride. Mass spectrometry, conductivity measurements, Mössbauer, UV-VIS, FTIR and elemental analysis were all in accordance with the proposed composition and the plausible geometry of [FeCl(HSCpy)]Cl. Mass spectrometry unequivocally detected the presence of the [FeCl(HSCpy)] + ion with a m/ z of 254.97 and intensity of 2 × 10 5.

  9. Metalloantibiotic Mn(II)-bacitracin complex mimicking manganese superoxide dismutase

    SciTech Connect

    Piacham, Theeraphon; Isarankura-Na-Ayudhya, Chartchalerm; Nantasenamat, Chanin; Yainoy, Sakda; Ye Lei; Buelow, Leif; Prachayasittikul, Virapong . E-mail: mtvpr@mucc.mahidol.ac.th

    2006-03-24

    Superoxide dismutase (SOD) activities of various metallobacitracin complexes were evaluated using the riboflavin-methionine-nitro blue tetrazolium assay. The radical scavenging activity of various metallobacitracin complexes was shown to be higher than those of the negative controls, e.g., free transition metal ions and metal-free bacitracin. The SOD activity of the complex was found to be in the order of Mn(II) > Cu(II) > Co(II) > Ni(II). Furthermore, the effect of bacitracin and their complexation to metals on various microorganisms was assessed by antibiotic susceptibility testing. Moreover, molecular modeling and quantum chemical calculation of the metallobacitracin complex was performed to evaluate the correlation of electrostatic charge of transition metal ions on the SOD activity.

  10. Copper(II)-8-hydroxquinoline coprecipitation system for preconcentration and separation of cobalt(II) and manganese(II) in real samples.

    PubMed

    Soylak, Mustafa; Kaya, Betul; Tuzen, Mustafa

    2007-08-25

    A separation-preconcentration procedure based on the coprecipitation of cobalt(II) and manganese(II) ions with copper(II)-8-hydroxquinoline system has been developed. The analytical parameters including pH, amount of copper(II) as carrier element, amount of 8-hydroxquinoline, sample volume, etc., was investigated for the quantitative recoveries of Co(II) and Mn(II). No interferic effects were observed from the concomitant ions which are present in real samples. The detection limits for analyte ions by three sigma criteria were 0.86microgL(-1) for cobalt and 0.98microgL(-1) for manganese. The validation of the presented preconcentration procedure was performed by the analysis of NIST SRM 2711 Montana soil and GBW 07605 Tea certified reference materials. The procedure presented was applied to the analyte contents of real samples including natural waters and some food samples with successfully analytical results.

  11. In Situ Determination of Manganese(II) Speciation in Deinococcus radiodurans by High Magnetic Field EPR

    PubMed Central

    Tabares, Leandro C.; Un, Sun

    2013-01-01

    High magnetic field high frequency electron paramagnetic resonance techniques were used to measure in situ Mn(II) speciation in Deinococcus radiodurans, a radiation-resistant bacteria capable of accumulating high concentrations of Mn(II). It was possible to identify and quantify the evolution of Mn(II) species in intact cells at various stages of growth. Aside from water, 95-GHz high field electron nuclear double resonance showed that the Mn(II) ions are bound to histidines and phosphate groups, mostly from fructose-1,6-bisphosphate but also inorganic phosphates and nucleotides. During stationary growth phase, 285-GHz continuous wave EPR measurements showed that histidine is the most common ligand to Mn(II) and that significant amounts of cellular Mn(II) in D. radiodurans are bound to peptides and proteins. As much as 40% of the total Mn(II) was in manganese superoxide dismutase, and it is this protein and not smaller manganese complexes, as has been suggested recently, that is probably the primary defense against superoxide. PMID:23303180

  12. Photosystem II Functionality in Barley Responds Dynamically to Changes in Leaf Manganese Status

    PubMed Central

    Schmidt, Sidsel B.; Powikrowska, Marta; Krogholm, Ken S.; Naumann-Busch, Bianca; Schjoerring, Jan K.; Husted, Søren; Jensen, Poul E.; Pedas, Pai R.

    2016-01-01

    A catalytic manganese (Mn) cluster is required for the oxidation of water in the oxygen-evolving complex (OEC) of photosystem II (PSII) in plants. Despite this essential role of Mn in generating the electrons driving photosynthesis, limited information is available on how Mn deficiency affects PSII functionality. We have here used parameters derived from measurements of fluorescence induction kinetics (OJIP transients), non-photochemical quenching (NPQ) and PSII subunit composition to investigate how latent Mn deficiency changes the photochemistry in two barley genotypes differing in Mn efficiency. Mn deficiency caused dramatic reductions in the quantum yield of PSII and led to the appearance of two new inflection points, the K step and the D dip, in the OJIP fluorescence transients, indicating severe damage to the OEC. In addition, Mn deficiency decreased the ability to induce NPQ in the light, rendering the plants incapable of dissipating excess energy in a controlled way. Thus, the Mn deficient plants became severely affected in their ability to recover from high light-induced photoinhibition, especially under strong Mn deficiency. Interestingly, the Mn-efficient genotype was able to maintain a higher NPQ than the Mn-inefficient genotype when exposed to mild Mn deficiency. However, during severe Mn deficiency, there were no differences between the two genotypes, suggesting a general loss of the ability to disassemble and repair PSII. The pronounced defects of PSII activity were supported by a dramatic decrease in the abundance of the OEC protein subunits, PsbP and PsbQ in response to Mn deficiency for both genotypes. We conclude that regulation of photosynthetic performance by means of maintaining and inducing NPQ mechanisms contribute to genotypic differences in the Mn efficiency of barley genotypes growing under conditions with mild Mn deficiency. PMID:27933084

  13. Manganese-enhanced MRI of rat brain based on slow cerebral delivery of manganese(II) with silica-encapsulated Mn x Fe(1-x) O nanoparticles.

    PubMed

    Chen, Wei; Lu, Fang; Chen, Chiao-Chi V; Mo, Kuan-Chi; Hung, Yann; Guo, Zhi-Xuan; Lin, Chia-Hui; Lin, Ming-Huang; Lin, Yu-Hsuan; Chang, Chen; Mou, Chung-Yuan

    2013-09-01

    In this work, we report a monodisperse bifunctional nanoparticle system, MIO@SiO2 -RITC, as an MRI contrast agent [core, manganese iron oxide (MIO); shell, amorphous silica conjugated with rhodamine B isothiocyanate (RITC)]. It was prepared by thermal decomposition and modified microemulsion methods. The nanoparticles with varying iron to manganese ratios displayed different saturated magnetizations and relaxivities. In vivo MRI of rats injected intravenously with MIO@SiO2-RITC nanoparticles exhibited enhancement of the T1 contrast in brain tissue, in particular a time-delayed enhancement in the hippocampus, pituitary gland, striatum and cerebellum. This is attributable to the gradual degradation of MIO@SiO2-RITC nanoparticles in the liver, resulting in the slow release of manganese(II) [Mn(II)] into the blood pool and, subsequently, accumulation in the brain tissue. Thus, T1-weighted contrast enhancement was clearly detected in the anatomic structure of the brain as time progressed. In addition, T2*-weighted images of the liver showed a gradual darkening effect. Here, we demonstrate the concept of the slow release of Mn(II) for neuroimaging. This new nanoparticle-based manganese contrast agent allows one simple intravenous injection (rather than multiple infusions) of Mn(II) precursor, and results in delineation of the detailed anatomic neuroarchitecture in MRI; hence, this provides the advantage of the long-term study of neural function. Copyright © 2013 John Wiley & Sons, Ltd.

  14. The use of Apatite II™ to remove divalent metal ions zinc(II), lead(II), manganese(II) and iron(II) from water in passive treatment systems: column experiments.

    PubMed

    Oliva, Josep; De Pablo, Joan; Cortina, José-Luis; Cama, Jordi; Ayora, Carlos

    2010-12-15

    The conventional passive treatments for remediation of acid mine drainage using calcite are not totally efficient in the removal of certain heavy metal ions. Although pH increases to 6-7 and promotes the precipitation of trivalent and some divalent metals as hydroxides and carbonates, the remaining concentrations of some divalent metals ions do not fulfill the environmental regulations. In this study, Apatite II™, a biogenic hydroxyapatite, is used as an alternative reactive material to remove Zn(II), Pb(II), Mn(II) and Fe(II). Apatite II™ reacted with acid water releasing phosphate and increasing pH up to 6.5-7, inducing metals to precipitate mainly as metal-phosphates: zinc precipitated as hopeite, Zn(3)(PO(4))(2)·4H(2)O, lead as pyromorfite, Pb(5)(PO(4))(3)OH, manganese as metaswitzerite, Mn(3)(PO(4))(2)·4H(2)O and iron as vivianite, Fe(3)(PO(4))(2)·8H(2)O. Thus, metal concentrations from 30 to 75 mg L(-1) in the inflowing water were depleted to values below 0.10 mg L(-1). Apatite II™ dissolution is sufficiently fast to treat flows as high as 50 m/a. For reactive grain size of 0.5-3mm, the treatment system ends due to coating of the grains by precipitates, especially when iron and manganese are present in the solution. Copyright © 2010 Elsevier B.V. All rights reserved.

  15. Oxidative damage and neurodegeneration in manganese-induced neurotoxicity

    SciTech Connect

    Milatovic, Dejan; Yu, Yingchun

    2009-10-15

    Exposure to excessive manganese (Mn) levels results in neurotoxicity to the extrapyramidal system and the development of Parkinson's disease (PD)-like movement disorder, referred to as manganism. Although the mechanisms by which Mn induces neuronal damage are not well defined, its neurotoxicity appears to be regulated by a number of factors, including oxidative injury, mitochondrial dysfunction and neuroinflammation. To investigate the mechanisms underlying Mn neurotoxicity, we studied the effects of Mn on reactive oxygen species (ROS) formation, changes in high-energy phosphates (HEP), neuroinflammation mediators and associated neuronal dysfunctions both in vitro and in vivo. Primary cortical neuronal cultures showed concentration-dependent alterations in biomarkers of oxidative damage, F{sub 2}-isoprostanes (F{sub 2}-IsoPs) and mitochondrial dysfunction (ATP), as early as 2 h following Mn exposure. Treatment of neurons with 500 {mu}M Mn also resulted in time-dependent increases in the levels of the inflammatory biomarker, prostaglandin E{sub 2} (PGE{sub 2}). In vivo analyses corroborated these findings, establishing that either a single or three (100 mg/kg, s.c.) Mn injections (days 1, 4 and 7) induced significant increases in F{sub 2}-IsoPs and PGE{sub 2} in adult mouse brain 24 h following the last injection. Quantitative morphometric analyses of Golgi-impregnated striatal sections from mice exposed to single or three Mn injections revealed progressive spine degeneration and dendritic damage of medium spiny neurons (MSNs). These findings suggest that oxidative stress, mitochondrial dysfunction and neuroinflammation are underlying mechanisms in Mn-induced neurodegeneration.

  16. Structure and nature of manganese(II) imidazole complexes in frozen aqueous solutions.

    PubMed

    Un, Sun

    2013-04-01

    A common feature of a large majority of the manganese metalloenzymes, as well as many synthetic biomimetic complexes, is the bonding between the manganese ion and imidazoles. This interaction was studied by examining the nature and structure of manganese(II) imidazole complexes in frozen aqueous solutions using 285 GHz high magnet-field continuous-wave electron paramagnetic resonance (cw-HFEPR) and 95 GHz pulsed electron-nuclear double resonance (ENDOR) and pulsed electron-double resonance detected nuclear magnetic resonance (PELDOR-NMR). The (55)Mn hyperfine coupling and isotropic g values of Mn(II) in frozen imidazole solutions continuously decreased with increasing imidazole concentration. ENDOR and PELDOR-NMR measurements demonstrated that the structural basis for this behavior arose from the imidazole concentration-dependent distribution of three six-coordinate and two four-coordinate species: [Mn(H2O)6](2+), [Mn(imidazole)(H2O)5](2+), [Mn(imidazole)2(H2O)4](2+), [Mn(imidazole)3(H2O)](2+), and [Mn(imidazole)4](2+). The hyperfine and g values of manganese proteins were also fully consistent with this imidazole effect. Density functional theory methods were used to calculate the structures, spin and charge densities, and hyperfine couplings of a number of different manganese imidazole complexes. The use of density functional theory with large exact-exchange admixture calculations gave isotropic (55)Mn hyperfine couplings that were semiquantitative and of predictive value. The results show that the covalency of the Mn-N bonds play an important role in determining not only magnetic spin parameters but also the structure of the metal binding site. The relationship between the isotropic (55)Mn hyperfine value and the number of imidazole ligands provides a quick and easy test for determining whether a protein binds an Mn(II) ion using histidine residues and, if so, how many are involved. Application of this method shows that as much as 40% of the Mn(II) ions in

  17. Amorphous manganese-calcium oxides as a possible evolutionary origin for the CaMn₄ cluster in photosystem II.

    PubMed

    Najafpour, Mohammad Mahdi

    2011-06-01

    In this paper a few calcium-manganese oxides and calcium-manganese minerals are studied as catalysts for water oxidation. The natural mineral marokite is also studied as a catalyst for water oxidation for the first time. Marokite is made up of edge-sharing Mn(3+) in a distorted octahedral environment and eight-coordinate Ca(2+) centered polyhedral layers. The structure is similar to recent models of the oxygen evolving complex in photosystem II. Thus, the oxygen evolving complex in photosystem II does not have an unusual structure and could be synthesized hydrothermally. Also in this paper, oxygen evolution is studied with marokite (CaMn₂O₄), pyrolusite (MnO₂) and compared with hollandite (Ba(0.2)Ca(0.15)K(0.3)Mn(6.9)Al(0.2)Si(0.3)O(16)), hausmannite (Mn₃O₄), Mn₂O₃.H₂O, Ca Mn₃O₆.H₂O, CaMn₄O₈.H₂O, CaMn₂O₄.H₂O and synthetic marokite (CaMn₂O₄). I propose that the origin of the oxygen evolving complex in photosystem II resulted from absorption of calcium and manganese ions that were precipitated together in the archean oceans by protocyanobacteria because of changing pH from ~5 to ~8-10. As reported in this paper, amorphous calcium-manganese oxides with different ratios of manganese and calcium are effective catalysts for water oxidation. The bond types and lengths of the calcium and manganese ions in the calcium-manganese oxides are directly comparable to those in the OEC. This primitive structure of these amorphous calcium-manganese compounds could be changed and modified by environmental groups (amino acids) to form the oxygen evolving complex in photosystem II.

  18. Chelate electronic properties control the redox behaviour and superoxide reactivity of seven-coordinate manganese(II) complexes.

    PubMed

    Liu, Gao-Feng; Dürr, Katharina; Puchta, Ralph; Heinemann, Frank W; van Eldik, Rudi; Ivanović-Burmazović, Ivana

    2009-08-28

    We have synthesized and characterized two Mn(II) seven-coordinate complexes with N5 pentadentate ligands, which contain hydrazone and hydrazide groups respectively. We have shown that insertion of hydrazido (amido) groups into the ligand sphere increases the negative charge of the chelate, without changing a donor atom set and coordination geometry, and radically modulate a redox activity of seven-coordinate manganese complexes, which is important for the function of manganese as a superoxide dismutase catalytic center.

  19. Preparation of electrochromic thin films by transformation of manganese(II) carbonate

    NASA Astrophysics Data System (ADS)

    Stojkovikj, Sasho; Najdoski, Metodija; Koleva, Violeta; Demiri, Sani

    2013-10-01

    A new chemical bath method for deposition of manganese(II) carbonate thin film on electroconductive FTO glass substrates is designed. The homogeneous thin films with thickness in the range of 70 to 500 nm are deposited at about 98 °C from aqueous solution containing urea and MnCl2. The chemical process is based on a low temperature hydrolysis of the manganese complexes with urea. Three types of films are under consideration: as-deposited, annealed and electrochemically transformed thin films. The structure of the films is studied by XRD, IR and Raman spectroscopy. Electrochemical and optical properties are examined in eight different electrolytes (neutral and alkaline) and the best results are achieved in two component aqueous solution of 0.1 M KNO3 and 0.01 M KOH. It is established that the as-deposited MnCO3 film undergoes electrochemically transformation into birnessite-type manganese(IV) oxide films, which exhibit electrochromic color changes (from bright brown to pale yellow and vice versa) with 30% difference in the transmittance of the colored and bleached state at 400 nm.

  20. Oxidant Selection for the Treatment of Manganese (II), Iron (II), and Arsenic (III) in Groundwaters

    EPA Science Inventory

    In order to comply with the United States Environmental Protection Agency’s (U.S. EPA’s) arsenic standard and the manganese and iron secondary maximum contaminant levels (MCLs) in water (10µg/L, 50µg/L, and 300µg/L, respectively), many Midwestern water utilities must add a strong...

  1. Oxidant Selection for the Treatment of Manganese (II), Iron (II), and Arsenic (III) in Groundwaters

    EPA Science Inventory

    In order to comply with the United States Environmental Protection Agency’s (U.S. EPA’s) arsenic standard and the manganese and iron secondary maximum contaminant levels (MCLs) in water (10µg/L, 50µg/L, and 300µg/L, respectively), many Midwestern water utilities must add a strong...

  2. A novel manganese complex, Mn-(II) N-(2-hydroxy acetophenone) glycinate overcomes multidrug-resistance in cancer.

    PubMed

    Ghosh, Ruma Dey; Banerjee, Kaushik; Das, Satyajit; Ganguly, Avishek; Chakraborty, Paramita; Sarkar, Avijit; Chatterjee, Mitali; Choudhuri, Soumitra K

    2013-07-16

    Multidrug resistance (MDR) remains a significant problem for effective cancer chemotherapy. In spite of considerable advances in drug discovery, most of the cancer cases still stay incurable because of resistance to chemotherapy. We synthesized a novel, Mn (II) complex (chelate), viz., manganese N-(2-hydroxy acetophenone) glycinate (MnNG) that exhibits considerable efficacy to overcome drug resistant cancer. The antiproliferative activity of MnNG was studied on doxorubicin resistant and sensitive human T lymphoblastic leukemia cells (CEM/ADR 5000 and CCRF/CEM). MnNG induced apoptosis significantly in CEM/ADR 5000 cells probably through generation of reactive oxygen species. Moreover, intraperitoneal (i.p.) application of MnNG at non-toxic doses caused significant increase in the life-span of Swiss albino mice bearing sensitive and doxorubicin resistant subline of Ehrlich ascites carcinoma cells.

  3. Synthesis of dihydromyricetin-manganese (II) complex and interaction with DNA

    NASA Astrophysics Data System (ADS)

    Guo, Qingquan; Yuan, Juan; Zeng, Jinhua; He, Xiangzhu; Li, Daguang

    2012-11-01

    Dihydromyricetin has many physiological functions and its metal complex could have better effects. DNA is very important in biological body, but little attention has been devoted to the relationship between dihydromyricetin-metal complex and the DNA. In this paper, dihydromyricetin-Mn (II) complex has been prepared and characterized using UV-vis absorption spectrophotometry, IR spectroscopy, elemental analysis, and thermal gravimetric analysis (TG-DTA Analysis). The interaction of dihydromyricetin-Mn (II) complex with DNA was investigated using UV-vis spectra, fluorescence measurements and viscosity measurements. The results indicate that the dihydromyricetin-manganese (II) complex can intercalate into the stacked base pairs of DNA with binding constant Kb = 5.64 × 104 M and compete with the strong intercalator ethidium bromide for the intercalative binding sites with Stern-Volmer quenching constant, Ksq = 1.16.

  4. Deficiency in the manganese efflux transporter SLC30A10 induces severe hypothyroidism in mice.

    PubMed

    Hutchens, Steven; Liu, Chunyi; Jursa, Thomas; Shawlot, William; Chaffee, Beth K; Yin, Weiling; Gore, Andrea C; Aschner, Michael; Smith, Donald R; Mukhopadhyay, Somshuvra

    2017-06-09

    Manganese is an essential metal that becomes toxic at elevated levels. Loss-of-function mutations in SLC30A10, a cell-surface-localized manganese efflux transporter, cause a heritable manganese metabolism disorder resulting in elevated manganese levels and parkinsonian-like movement deficits. The underlying disease mechanisms are unclear; therefore, treatment is challenging. To understand the consequences of loss of SLC30A10 function at the organism level, we generated Slc30a10 knock-out mice. During early development, knock-outs were indistinguishable from controls. Surprisingly, however, after weaning and compared with controls, knock-out mice failed to gain weight, were smaller, and died prematurely (by ∼6-8 weeks of age). At 6 weeks, manganese levels in the brain, blood, and liver of the knock-outs were ∼20-60-fold higher than controls. Unexpectedly, histological analyses revealed that the brain and liver of the knock-outs were largely unaffected, but their thyroid exhibited extensive alterations. Because hypothyroidism leads to growth defects and premature death in mice, we assayed for changes in thyroid and pituitary hormones. At 6 weeks and compared with controls, the knock-outs had markedly reduced thyroxine levels (∼50-80%) and profoundly increased thyroid-stimulating hormone levels (∼800-1000-fold), indicating that Slc30a10 knock-out mice develop hypothyroidism. Importantly, a low-manganese diet produced lower tissue manganese levels in the knock-outs and rescued the phenotype, suggesting that manganese toxicity was the underlying cause. Our unanticipated discovery highlights the importance of determining the role of thyroid dysfunction in the onset and progression of manganese-induced disease and identifies Slc30a10 knock-out mice as a new model for studying thyroid biology. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  5. Manganese ions enhance mitochondrial H2O2 emission from Krebs cycle oxidoreductases by inducing permeability transition.

    PubMed

    Bonke, Erik; Siebels, Ilka; Zwicker, Klaus; Dröse, Stefan

    2016-10-01

    Manganese-induced toxicity has been linked to mitochondrial dysfunction and an increased generation of reactive oxygen species (ROS). We could recently show in mechanistic studies that Mn(2+) ions induce hydrogen peroxide (H2O2) production from the ubiquinone binding site of mitochondrial complex II (IIQ) and generally enhance H2O2 formation by accelerating the rate of superoxide dismutation. The present study with intact mitochondria reveals that manganese additionally enhances H2O2 emission by inducing mitochondrial permeability transition (mPT). In mitochondria fed by NADH-generating substrates, the combination of Mn(2+) and different respiratory chain inhibitors led to a dynamically increasing H2O2emission which was sensitive to the mPT inhibitor cyclosporine A (CsA) as well as Ru-360, an inhibitor of the mitochondrial calcium uniporter (MCU). Under these conditions, flavin-containing enzymes of the mitochondrial matrix, e.g. the mitochondrial 2-oxoglutaratedehydrogenase (OGDH), were major sources of ROS. With succinate as substrate, Mn(2+) stimulated ROS production mainly at complex II, whereby the applied succinate concentration had a marked effect on the tendency for mPT. Also Ca(2+) increased the rate of H2O2 emission by mPT, while no direct effect on ROS-production of complex II was observed. The present study reveals a complex scenario through which manganese affects mitochondrial H2O2 emission: stimulating its production from distinct sites (e.g. site IIQ), accelerating superoxide dismutation and enhancing the emission via mPT which also leads to the loss of soluble components of the mitochondrial antioxidant systems and favors the ROS production from flavin-containing oxidoreductases of the Krebs cycle. Copyright © 2016 Elsevier Inc. All rights reserved.

  6. Synthesis, structural analysis, and magnetic properties of ethylmalonate-manganese(II) complexes.

    PubMed

    Déniz, Mariadel; Pasán, Jorge; Ferrando-Soria, Jesús; Fabelo, Oscar; Cañadillas-Delgado, Laura; Yuste, Consuelo; Julve, Miguel; Cano, Joan; Ruiz-Pérez, Catalina

    2011-11-07

    Five manganese(II) complexes of formulas [Mn(2)(Etmal)(2)(H(2)O)(2)(L)](n) (1-4) and {[Mn(Etmal)(2)(H(2)O)][Mn(H(2)O)(4)]}(n) (5) with H(2)Etmal = ethylmalonic acid (1-5) and L = 1,2-bis(4-pyridyl)ethane (bpa) (1), 4,4'-azobispyridine (azpy) (2), 4,4'-bipyridyl (4,4'-bpy) (3), and 1,2-bis(4-pyridyl)ethylene (bpe) (4) were synthesized and structurally characterized by single crystal X-ray diffraction. Their thermal behavior and variable-temperature magnetic properties were also investigated. The structure of the compounds 1-4 consists of corrugated layers of aquamanganese(II) units with intralayer carboxylate-ethylmalonate bridges in the anti-syn (equatorial-equatorial) coordination mode which are linked through bis-monodentate bpa (1), azpy (2), 4,4'-bpy (3), and bpe (4) ligands to build up a three-dimensional (3D) framework. The structure of compound 5 is made up by zigzag chains of manganese(II) ions with a regular alternation of [Mn(H(2)O)(4)](2+) and chiral (either Δ or λ enantiomeric forms) [Mn(Etmal)(2)(H(2)O)](2-) units within each chain. In contrast to the bidentate/bis-monodentate coordination mode of the Etmal ligand in 1-4, it adopts the bidentate/monodentate coordination mode in 5 with the bridging carboxylate-ethylmalonate also exhibiting the anti-syn conformation but connecting one equatorial and an axial position from adjacent metal centers. The manganese-manganese separation through the carboxylate-ethylmalonate bridge in 1-5 vary in the range 5.3167(4)-5.5336(7) Å. These values are much shorter than those across the extended bis-monodentate N-donors in 1-4 with longest/shortest values of 11.682(3) (3)/13.9745(9) Å (4). Compounds 1-5 exhibit an overall antiferromagnetic behavior, where the exchange pathway is provided by the carboxylate-ethylmalonate bridge. Monte Carlo simulations based on the classical spin approach (1-5) were used to successfully reproduce the magnetic data of 1-5. © 2011 American Chemical Society

  7. Diverse manganese(II)-oxidizing bacteria are prevalent in drinking water systems.

    PubMed

    Marcus, Daniel N; Pinto, Ameet; Anantharaman, Karthik; Ruberg, Steven A; Kramer, Eva L; Raskin, Lutgarde; Dick, Gregory J

    2017-04-01

    Manganese (Mn) oxides are highly reactive minerals that influence the speciation, mobility, bioavailability and toxicity of a wide variety of organic and inorganic compounds. Although Mn(II)-oxidizing bacteria are known to catalyze the formation of Mn oxides, little is known about the organisms responsible for Mn oxidation in situ, especially in engineered environments. Mn(II)-oxidizing bacteria are important in drinking water systems, including in biofiltration and water distribution systems. Here, we used cultivation dependent and independent approaches to investigate Mn(II)-oxidizing bacteria in drinking water sources, a treatment plant and associated distribution system. We isolated 29 strains of Mn(II)-oxidizing bacteria and found that highly similar 16S rRNA gene sequences were present in all culture-independent datasets and dominant in the studied drinking water treatment plant. These results highlight a potentially important role for Mn(II)-oxidizing bacteria in drinking water systems, where biogenic Mn oxides may affect water quality in terms of aesthetic appearance, speciation of metals and oxidation of organic and inorganic compounds. Deciphering the ecology of these organisms and the factors that regulate their Mn(II)-oxidizing activity could yield important insights into how microbial communities influence the quality of drinking water. © 2016 Society for Applied Microbiology and John Wiley & Sons Ltd.

  8. Manganese(II) octa-uranium(IV) hepta-deca-sulfide.

    PubMed

    Oh, George N; Ibers, James A

    2011-09-01

    Single crystals of manganese(II) octa-uranium(IV) hepta-deca-sulfide, MnU(8)S(17), were grown from the reaction of the elements in a RbCl flux. MnU(8)S(17) crystallizes in the space group C2/m in the CrU(8)S(17) structure type. The asymmetric unit is composed of the following atoms with site symmetries shown: U1 (1), U2 (m), U3 (m), Mn1 (2/m), S1 (1), S2 (1); S3 (m), S4 (m), S5 (m), S6 (m) and S7 (2/m). The three U(IV) atoms are each coordinated by eight S atoms in a bicapped trigonal-prismatic arrangement. The Mn(II) atom is coordinated by six S atoms in a distorted octa-hedral arrangement.

  9. Water exchange in manganese-based water-oxidizing catalysts in photosynthetic systems: from the water-oxidizing complex in photosystem II to nano-sized manganese oxides.

    PubMed

    Najafpour, Mohammad Mahdi; Isaloo, Mohsen Abbasi; Eaton-Rye, Julian J; Tomo, Tatsuya; Nishihara, Hiroshi; Satoh, Kimiyuki; Carpentier, Robert; Shen, Jian-Ren; Allakhverdiev, Suleyman I

    2014-09-01

    The water-oxidizing complex (WOC), also known as the oxygen-evolving complex (OEC), of photosystem II in oxygenic photosynthetic organisms efficiently catalyzes water oxidation. It is, therefore, responsible for the presence of oxygen in the Earth's atmosphere. The WOC is a manganese-calcium (Mn₄CaO₅(H₂O)₄) cluster housed in a protein complex. In this review, we focus on water exchange chemistry of metal hydrates and discuss the mechanisms and factors affecting this chemical process. Further, water exchange rates for both the biological cofactor and synthetic manganese water splitting are discussed. The importance of fully unveiling the water exchange mechanism to understand the chemistry of water oxidation is also emphasized here. This article is part of a special issue entitled: photosynthesis research for sustainability: keys to produce clean energy.

  10. Hydrothermal synthesis of silico-manganese nanohybrid for Cu(II) adsorption from aqueous solution

    NASA Astrophysics Data System (ADS)

    Zhu, Qiufeng; Wang, Liting; An, Zehuan; Ye, Hong; Feng, Xudong

    2016-05-01

    A novel silico-manganese nanohybrid adsorbent (SMNA) was synthesized by a facile hydrothermal method, and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), nitrogen adsorption-desorption, Fourier transform infrared spectroscopy (FT-IR) and zeta potential measurement. The adsorption of Cu(II) ions from aqueous solution on the SMNA was investigated with variations in contact time, pH and initial Cu(II) concentration. The results showed that hydrothermal method would generate nanowire/nanorod incomplete crystallite (δ-MnO2) adsorbent. The adsorption of Cu(II) onto SMNA increased sharply within 25 min and reached equilibrium gradually. The maximum adsorption capacities of SMNA for Cu(II) were ∼40-88 mg g-1, which was lower than δ-MnO2 (92.42 mg g-1) but had a lower pH dependency. As compared with δ-MnO2, higher adsorption capacities of SMNA (7.5-15 wt% of silica doping amount) for Cu(II) could be observed when pH of the aqueous solution was low (<4). The pseudo-second-order model was the best choice to describe the adsorption behavior of Cu(II) onto SMNA, suggesting that the removal of Cu(II) by the as-prepared adsorbents was dominated by migration of Cu(II). The possibility of Cu(II) recovery was also investigated and it revealed that SMNA was a promising recyclable adsorbent for removal of heavy metal ions in water and wastewater treatment.

  11. Removal of Pb(II) from aqueous solution by hydrous manganese dioxide: adsorption behavior and mechanism.

    PubMed

    Xu, Meng; Wang, Hongjie; Di, Lei; Qu, Dan; Zhai, Yujia; Wang, Yili

    2013-03-01

    Hydrous manganese dioxide (HMO) synthesized by redox of potassium permanganate and hydrogen peroxide was used as an adsorbent for Pb(II) removal. The specific surface area, pore volume and BJH pore diameter of the HMO were 79.31 m2/g, 0.07 cm3/g and 3.38 nm, respectively. The adsorption equilibrium at 298 K could be well described by the Langmuir isotherm equation with qmax value of 352.55 mg/g. The negative values of deltaG and the positive values of deltaH and deltaS indicated the adsorption process was spontaneous and endothermic. The pseudo second-order equation could best fit the adsorption data. The value of the calculated activation energy for Pb(II) adsorption onto the HMO was 38.23 kJ/mol. The uptake of Pb(II) by HMO was correlated with increasing surface hydroxyl group content and the main adsorbed speciation was PbOH+. The final chemical state of Pb(II) on the surface of HMO was similar to PbO. HMO was a promising candidate for Pb(II) removal from aqueous solution.

  12. A one-dimensional chain structure based on unusual tetranuclear manganese(II) clusters.

    PubMed

    Che, Guang Bo; Wang, Jian; Liu, Chun Bo; Li, Xiu Ying; Liu, Bo

    2008-11-01

    The title coordination polymer, poly[bis(mu(4)-biphenyl-2,2'-dicarboxylato)(dipyrido[3,2-a:2',3'-c]phenazine)manganese(II)], [Mn(2)(C(14)H(8)O(4))(2)(C(18)H(10)N(4))](n), was obtained through the reaction of MnCl(2).4H(2)O, biphenyl-2,2'-dicarboxylic acid (H(2)dpdc) and dipyrido[3,2-a:2',3'-c]phenazine (L) under hydrothermal conditions. The asymmetric unit contains two crystallographically unique Mn(II) ions, one unique L ligand and two unique dpdc ligands. One Mn ion is six-coordinated by four O atoms from three different dpdc ligands and two N atoms from one L ligand, adopting a distorted octahedral coordination geometry. The distortions from ideal octahedral geometry are largely due to the presence of chelating ligands and the resulting acute N-Mn-N and O-Mn-O angles. The second Mn ion is coordinated in a distorted trigonal bipyramidal fashion by five O atoms from four distinct dpdc ligands. Four Mn(II) ions are bridged by the carboxylate groups of the dpdc ligands to form an unusual tetranuclear Mn(II) cluster. Clusters are further connected by the aromatic backbone of the dicarboxylate ligands, forming a one-dimensional chain structure along the b axis. The title compound is the first example of a chain structure based on a tetranuclear Mn(II) cluster.

  13. Possible Parkinson's Disease Induced by Chronic Manganese Supplement Ingestion.

    PubMed

    Schuh, Michael J

    2016-12-01

    The objective is to report a case of possible neurotoxicity resulting from an incorrect dietary supplement for osteoporosis taken at a toxic dose. The case study examined here is a 37-year-old African-American female who consumed excessive manganese over a period of years, resulting in Parkinson's disease (PD). This patient was referred to the pharmacist pharmacotherapy service by a neurology physician. PD has been shown in the medical literature to be caused by chronic exposure to high levels of manganese. It may be concluded that daily doses of manganese well above the upper limit of 9 mg per day were taken by this patient for an extended period of time, possibly causing PD via manganism. This case illustrates the unknown risks taken by patients who use excessive amounts of over-the-counter herbals and supplements and how pharmacists can assist patients and physicians in the proper use of these popular products. AI = Adequate intake, EMS = Eosinophilia myalgia syndrome, MTM = Medication therapy management, UL = Tolerable upper limit.

  14. Leucine 245 is a critical residue for folding and function of the manganese stabilizing protein of photosystem II.

    PubMed

    Lydakis-Simantiris, N; Betts, S D; Yocum, C F

    1999-11-23

    In solution, Manganese Stabilizing Protein, the polypeptide which is responsible for the structural and functional integrity of the manganese cluster in photosystem II, is a natively unfolded protein with a prolate ellipsoid shape [Lydakis-Simantiris et al. (1999) Biochemistry 38, 404-414; Zubrzycki et al. (1998) Biochemistry 37, 13553-13558]. The C-terminal tripeptide of Manganese Stabilizing Protein was shown to be critical for binding to photosystem II and restoration of O(2) evolution activity [Betts et al. (1998) Biochemistry 37, 14230-14236]. Here, we report new biochemical, hydrodynamic, and spectroscopic data on mutants E246K, E246STOP, L245E, L245STOP, and Q244STOP. Truncation of the final dipeptide (E246STOP) or substitution of Glu246 with Lys resulted in no significant changes in secondary and tertiary structures of Manganese Stabilizing Protein as monitored by CD spectroscopy. The apparent molecular mass of the protein remained unchanged, both mutants were able to rebind to photosystem II, and both proteins reactivate O(2) evolution. Manganese Stabilizing Protein lacking the final tripeptide (L245STOP), or substitution of Glu for Leu245 dramatically modified the protein's solution structure. The apparent molecular masses of these mutants increased significantly, which might indicate unfolding of the protein in solution. This was verified by CD spectroscopy. Both mutant proteins rebound to photosystem II with lower affinities, and activation of O(2) evolution was decreased dramatically. Enhancement of these defects was observed upon removal of the final tetrapeptide (Q244STOP). These results indicate that Leu245 is essential to maintaining Manganese Stabilizing Protein's solution structure in a conformation that promotes efficient binding to photosystem II and/or for the subsequent steps that lead to enzyme activation. Based on an analysis of the properties of C-terminal mutations, a hypothesis for structural requirements for functional binding of

  15. Two-dimensional HYSCORE spectroscopy of superoxidized manganese catalase: a model for the oxygen-evolving complex of photosystem II.

    PubMed

    Coates, Christopher S; Milikisiyants, Sergey; Chatterjee, Ruchira; Whittaker, Mei M; Whittaker, James W; Lakshmi, K V

    2015-04-16

    The solar water-splitting protein complex, photosystem II (PSII), catalyzes one of the most energetically demanding reactions in Nature by using light energy to drive a catalyst capable of oxidizing water. The water oxidation reaction takes place at the tetra-nuclear manganese calcium-oxo (Mn4Ca-oxo) cluster at the heart of the oxygen-evolving complex (OEC) of PSII. Previous studies have determined the magnetic interactions between the paramagnetic Mn4Ca-oxo cluster and its environment in the S2 state of the OEC. The assignments for the electron-nuclear magnetic interactions that were observed in these studies were facilitated by the use of synthetic dimanganese di-μ-oxo complexes. However, there is an immense need to understand the effects of the protein environment on the coordination geometry of the Mn4Ca-oxo cluster in the OEC of PSII. In the present study, we use a proteinaceous model system to examine the protein ligands that are coordinated to the dimanganese catalytic center of manganese catalase from Lactobacillus plantarum. We utilize two-dimensional hyperfine sublevel correlation (2D HYSCORE) spectroscopy to detect the weak magnetic interactions of the paramagnetic dinuclear manganese catalytic center of superoxidized manganese catalase with the nitrogen and proton atoms of the surrounding protein environment. We obtain a complete set of hyperfine interaction parameters for the protons of a water molecule that is directly coordinated to the dinuclear manganese center. We also obtain a complete set of hyperfine and quadrupolar interaction parameters for two histidine ligands as well as a coordinated azide ligand, in azide-treated superoxidized manganese catalase. On the basis of the values of the hyperfine interaction parameters of the dimanganese model, manganese catalase, and those of the S2 state of the OEC of PSII, for the first time, we discuss the impact of a proteinaceous environment on the coordination geometry of multinuclear manganese clusters.

  16. Small-angle x-ray scattering studies of the manganese stabilizing subunit in photosystem II.

    SciTech Connect

    Svensson, B.; Tiede, D. M.; Barry, B. A.; Univ. of Minnesota

    2002-08-29

    Small-angle X-ray scattering studies (SAXS) were used to determine the size, shape, and oligomeric composition of the manganese stabilizing protein (MSP) of photosystem II. This extrinsic protein subunit plays an important role in photosynthetic oxygen evolution. As its name implies, MSP stabilizes the tetranuclear Mn cluster of the water oxidation complex. Removal of MSP lowers activity and decreases the stability of active-site manganese. Reconstitution of MSP reverses these effects. In this study, MSP was extracted from spinach PSII membranes using CaCl{sub 2} or urea. Through the use of MALDI-TOF mass spectrometry, the molecular weight of MSP was determined to be 26.53 kDa. X-ray scattering results show that both samples display a monodisperse scattering pattern; this pattern is consistent with a homogeneous protein solution. The CaCl{sub 2} extracted and urea extracted MSP samples have radii of gyration of 25.9 {+-} 0.4 and 27.0 {+-} 0.01 {angstrom}, respectively. MSP is shown to be monomeric in solution. This was determined using a cytochrome c standard and the scattering intensity, extrapolated to zero scattering angle, which is proportional to the molecular weight. This SAXS study suggests that, in solution, MSP is a monomeric, elongated prolate ellipsoid with dimensions, 112 x 23 x 23 {angstrom}{sup 3} and an axial ratio of 4.8.

  17. Spectroscopic techniques and cyclic voltammetry with synthesis: Manganese(II) coordination stability and its ligand field parameters effect on macrocyclic ligands

    NASA Astrophysics Data System (ADS)

    Kumar, Rajiv; Chandra, Sulekh

    2007-05-01

    Manganese(II) macrocyclic complexes are prepared with different macrocyclic ligands, containing cyclic skeleton bearing organic components which have different chromospheres like N, O and S donor atoms and stereochemistry. Thus, six macrocyclic ligands, were prepared and their capacity to retain the manganese(II) ion in solid as well as in aqueous solution was determined and characterized by elemental analyses, molar conductance measurements, magnetic susceptibility measurements, mass, 1H NMR, IR, electronic spectral and cyclic voltammetric studies. The electronic spectrum of this system showed a dependence that may be consistent with the formation of stable complexes and coordination behaviour of the ions. ESR spectra of all the complexes are recorded in solid as well as solution, which show the oxidation state of the manganese(II). Spin Hamiltonian manganese(II), which can be defined as the magnetic field vector (ℋ): ℋ=gβHS+DSz2-{35}/{12}+E[Sz2-Sy2]+ASI+ 1/6 a Sx4+Sy4+Sz4-{707}/{16}+ 1/180 F{35Sz2-475}/{2Sz2+3255/10} Significant distortion of the manganese(II) ion in observed geometry is evident from the angle subtended by the different membered chelate rings and the angles spanned by trans donor atoms octahedral geometry. Cyclic voltammetric studies indicate that complexes with all ligands undergoes one electron oxidation from manganese(II) to manganese(III) followed by a further oxidation to manganese(IV) at a significantly more positive potential.

  18. The autophagic- lysosomal pathway determines the fate of glial cells under manganese- induced oxidative stress conditions.

    PubMed

    Gorojod, R M; Alaimo, A; Porte Alcon, S; Pomilio, C; Saravia, F; Kotler, M L

    2015-10-01

    Manganese (Mn) overexposure is frequently associated with the development of a neurodegenerative disorder known as Manganism. The Mn-mediated generation of reactive oxygen species (ROS) promotes cellular damage, finally leading to apoptotic cell death in rat astrocytoma C6 cells. In this scenario, the autophagic pathway could play an important role in preventing cytotoxicity. In the present study, we found that Mn induced an increase in the amount and total volume of acidic vesicular organelles (AVOs), a process usually related to the activation of the autophagic pathway. Particularly, the generation of enlarged AVOs was a ROS- dependent event. In this report we demonstrated for the first time that Mn induces autophagy in glial cells. This conclusion emerged from the results obtained employing a battery of autophagy markers: a) the increase in LC3-II expression levels, b) the formation of autophagic vesicles labeled with monodansylcadaverine (MDC) or LC3 and, c) the increase in Beclin 1/ Bcl-2 and Beclin 1/ Bcl-X(L) ratio. Autophagy inhibition employing 3-MA and mAtg5(K130R) resulted in decreased cell viability indicating that this event plays a protective role in Mn- induced cell death. In addition, mitophagy was demonstrated by an increase in LC3 and TOM-20 colocalization. On the other hand, we proposed the occurrence of lysosomal membrane permeabilization (LMP) based in the fact that cathepsins B and D activities are essential for cell death. Both cathepsin B inhibitor (Ca-074 Me) or cathepsin D inhibitor (Pepstatin A) completely prevented Mn- induced cytotoxicity. In addition, low dose of Bafilomycin A1 showed a similar effect, a finding that adds evidence about the lysosomal role in Mn cytotoxicity. Finally, in vivo experiments demonstrated that Mn induces injury and alters LC3 expression levels in rat striatal astrocytes. In summary, our results demonstrated that autophagy is activated to counteract the harmful effect caused by Mn. These data is valuable to

  19. Nutrient input influences fungal community composition and size and can stimulate manganese (II) oxidation in caves.

    PubMed

    Carmichael, Sarah K; Zorn, Bryan T; Santelli, Cara M; Roble, Leigh A; Carmichael, Mary J; Bräuer, Suzanna L

    2015-08-01

    Little is known about the fungal role in biogeochemical cycling in oligotrophic ecosystems. This study compared fungal communities and assessed the role of exogenous carbon on microbial community structure and function in two southern Appalachian caves: an anthropogenically impacted cave and a near-pristine cave. Due to carbon input from shallow soils, the anthropogenically impacted cave had an order of magnitude greater fungal and bacterial quantitative-polymerase chain reaction (qPCR) gene copy numbers, had significantly greater community diversity, and was dominated by ascomycotal phylotypes common in early phase, labile organic matter decomposition. Fungal assemblages in the near-pristine cave samples were dominated by Basidiomycota typically found in deeper soils (and/or in late phase, recalcitrant organic matter decomposition), suggesting more oligotrophic conditions. In situ carbon and manganese (II) [Mn(II)] addition over 10 weeks resulted in growth of fungal mycelia followed by increased Mn(II) oxidation. A before/after comparison of the fungal communities indicated that this enrichment increased the quantity of fungal and bacterial cells, yet decreased overall fungal diversity. Anthropogenic carbon sources can therefore dramatically influence the diversity and quantity of fungi, impact microbial community function, and stimulate Mn(II) oxidation, resulting in a cascade of changes that can strongly influence nutrient and trace element biogeochemical cycles in karst aquifers. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

  20. Dinuclear cadmium(II), zinc(II), and manganese(II), trinuclear nickel(II), and pentanuclear copper(II) complexes with novel macrocyclic and acyclic Schiff-base ligands having enantiopure or racemic camphoric diamine components.

    PubMed

    Jiang, Jue-Chao; Chu, Zhao-Lian; Huang, Wei; Wang, Gang; You, Xiao-Zeng

    2010-07-05

    Four novel [3 + 3] Schiff-base macrocyclic ligands I-IV condensed from 2,6-diformyl-4-substituted phenols (R = CH(3) or Cl) and enantiopure or racemic camphoric diamines have been synthesized and characterized. Metal-ion complexations of these enantiopure and racemic [3 + 3] macrocyclic ligands with different cadmium(II), zinc(II), manganese(II), nickel(II), and copper(II) salts lead to the cleavage of Schiff-base C horizontal lineN double bonds and subsequent ring contraction of the macrocyclic ligands due to the size effects and the spatial restrictions of the coordination geometry of the central metals, the steric hindrance of ligands, and the counterions used. As a result, five [2 + 2] and one [1 + 2] dinuclear cadmium(II) complexes (1-6), two [2 + 2] dinuclear zinc(II) (7 and 8), and two [2 + 2] dinuclear manganese(II) (9 and 10) complexes together with one [1 + 1] trinuclear nickel(II) complex (11) and one [1 + 2] pentanuclear copper(II) complex (12), bearing enantiopure or racemic ligands, different substituent groups in the phenyl rings, and different anionic ligands (Cl(-), Br(-), OAc(-), and SCN(-)), have been obtained in which the chiral carbon atoms in the camphoric backbones are arranged in different ways (RRSS for the enantiopure ligands in 1, 2, 4, 5, and 7-10 and RSRS for the racemic ligands in 3, 6, 11, and 12). The steric hindrance effects of the methyl group bonded to one of the chiral carbon atoms of camphoric diamine units are believed to play important roles in the formation of the acyclic [1 + 1] trinuclear complex 11 and [1 + 2] dinuclear and pentanuclear complexes 6 and 12. In dinuclear cadmium(II), zinc(II), and manganese(II) complexes 1-10, the sequence of separations between the metal centers is consistent with that of the ionic radii shortened from cadmium(II) to manganese(II) to zinc(II) ions. Furthermore, UV-vis, circular dichroism, (1)H NMR, and fluorescence spectra have been used to characterize and compare the structural

  1. Immobilization of high concentrations of soluble Mn(II) from electrolytic manganese solid waste using inorganic chemicals.

    PubMed

    Du, Bing; Hou, Deyin; Duan, Ning; Zhou, Changbo; Wang, Jun; Dan, Zhigang

    2015-05-01

    Electrolytic manganese solid waste (EMSW) is a by-product of electrolytic manganese production and generally contains a high concentration of soluble Mn(II) (2000-3000 mg/L). Millions of tons of EMSW are stored in China, and the environmental pollution caused by manganese in this waste product is concerning. Unfortunately, little attention has been paid to the immobilization of manganese from industrial solid waste because manganese is absent from toxicological identification standards, and there is a lack of relevant quality standards in China. The objectives of this study were to immobilize soluble Mn(II) using chemical reagents, to analyze the immobilization mechanism, and to identify the most economical reagents. We investigated the immobilization degrees of soluble Mn(II) achieved by the reagents quicklime (CaO), carbonates (NaHCO₃ and Na₂CO₃), phosphates (Na₃PO₄, Na₂HPO₄, NH₄H₂PO₄, and Ca₁₀(PO₄)₆(OH)₂), and caustic magnesia (MgO) both individually and in combination. Our results showed that the use of 9% CaO+ 5% NaHCO₃, 9% CaO+ 5% Na₃PO₄, 10% MgO alone, or with 1-5% NaHCO₃ or 1-5% Na₂CO₃ can reduce the amount of Mn(II) leached to 100 mg/kg when the eluate pH was in the range of 6-9. The most economical reagent treatments were determined using K-means cluster analysis. Analysis of the immobilization mechanism showed that CaO + NaHCO₃ may be favorable for immobilizing soluble Mn(II) as precipitation and oxidation products because the addition of NaHCO₃ releases OH(-) and buffers the system.

  2. Subchronic inhalation of soluble manganese induces expression of hypoxia-associated angiogenic genes in adult mouse lungs

    SciTech Connect

    Bredow, Sebastian . E-mail: sbredow@LRRI.org; Falgout, Melanie M.; March, Thomas H.; Yingling, Christin M.; Malkoski, Stephen P.; Aden, James; Bedrick, Edward J.; Lewis, Johnnye L.; Divine, Kevin K.

    2007-06-01

    Although the lung constitutes the major exposure route for airborne manganese (Mn), little is known about the potential pulmonary effects and the underlying molecular mechanisms. Transition metals can mimic a hypoxia-like response, activating the hypoxia inducible factor-1 (HIF-1) transcription factor family. Through binding to the hypoxia-response element (HRE), these factors regulate expression of many genes, including vascular endothelial growth factor (VEGF). Increases in VEGF, an important biomarker of angiogenesis, have been linked to respiratory diseases, including pulmonary hypertension. The objective of this study was to evaluate pulmonary hypoxia-associated angiogenic gene expression in response to exposure of soluble Mn(II) and to assess the genes' role as intermediaries of potential pulmonary Mn toxicity. In vitro, 0.25 mM Mn(II) altered morphology and slowed the growth of human pulmonary epithelial cell lines. Acute doses between 0.05 and 1 mM stimulated VEGF promoter activity up to 3.7-fold in transient transfection assays. Deletion of the HRE within the promoter had no effect on Mn(II)-induced VEGF expression but decreased cobalt [Co(II)]-induced activity 2-fold, suggesting that HIF-1 may not be involved in Mn(II)-induced VEGF gene transcription. Nose-only inhalation to 2 mg Mn(II)/m{sup 3} for 5 days at 6 h/day produced no significant pulmonary inflammation but induced a 2-fold increase in pulmonary VEGF mRNA levels in adult mice and significantly altered expression of genes associated with murine angiogenesis. These findings suggest that even short-term exposures to soluble, occupationally relevant Mn(II) concentrations may alter pulmonary gene expression in pathways that ultimately could affect the lungs' susceptibility to respiratory disease.

  3. Hypothyroidism induced by loss of the manganese efflux transporter SLC30A10 may be explained by reduced thyroxine production.

    PubMed

    Liu, Chunyi; Hutchens, Steven; Jursa, Thomas; Shawlot, William; Polishchuk, Elena V; Polishchuk, Roman S; Dray, Beth K; Gore, Andrea C; Aschner, Michael; Smith, Donald R; Mukhopadhyay, Somshuvra

    2017-10-06

    SLC30A10 and SLC39A14 are manganese efflux and influx transporters, respectively. Loss-of-function mutations in genes encoding either transporter induce hereditary manganese toxicity. Patients have elevated manganese in the blood and brain and develop neurotoxicity. Liver manganese is increased in patients lacking SLC30A10 but not SLC39A14. These organ-specific changes in manganese were recently recapitulated in knockout mice. Surprisingly, Slc30a10 knockouts also had elevated thyroid manganese and developed hypothyroidism. To determine the mechanisms of manganese-induced hypothyroidism and understand how SLC30A10 and SLC39A14 cooperatively mediate manganese detoxification, here we produced Slc39a14 single and Slc30a10/Slc39a14 double knockout mice and compared their phenotypes with that of Slc30a10 single knockouts. Compared with wild-type controls, Slc39a14 single and Slc30a10/Slc39a14 double knockouts had higher manganese levels in the blood and brain but not in the liver. In contrast, Slc30a10 single knockouts had elevated manganese levels in the liver as well as in the blood and brain. Furthermore, SLC30A10 and SLC39A14 localized to the canalicular and basolateral domains of polarized hepatic cells, respectively. Thus, transport activities of both SLC39A14 and SLC30A10 are required for hepatic manganese excretion. Compared with Slc30a10 single knockouts, Slc39a14 single and Slc30a10/Slc39a14 double knockouts had lower thyroid manganese levels and normal thyroid function. Moreover, intrathyroid thyroxine levels of Slc30a10 single knockouts were lower than those of controls. Thus, the hypothyroidism phenotype of Slc30a10 single knockouts is induced by elevated thyroid manganese, which blocks thyroxine production. These findings provide new insights into the mechanisms of manganese detoxification and manganese-induced thyroid dysfunction. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  4. Purification and Characterization of the Manganese(II) Oxidizing Protein from Erythrobacter sp. SD-21

    NASA Astrophysics Data System (ADS)

    Nakama, K. R.; Lien, A.; Johnson, H. A.

    2013-12-01

    The manganese(II) oxidizing protein (Mop) found in the alpha-proteobacterium Erythrobacter sp. SD-21 catalyzes the formation of insoluble Mn(III/IV) oxides from soluble Mn(II). These Mn(III/IV) oxides formed are one of the strongest naturally occurring oxides, next to oxygen, and can be used to adsorb and oxidize toxic chemicals from the surrounding environment. Because of the beneficial use in the treatment of contaminated sources, the mechanism and biochemical properties of this novel enzyme are being studied. Due to low expression levels in the native host strain, purification of Mop has been problematic. To overcome this problem the gene encoding Mop, mopA, was cloned from the native host into a C-terminal histidine tag vector and expressed in Escherichia coli cells. Affinity chromatography under denaturing conditions have been applied in attempts to purify an active Mop. Western blots have confirmed that the protein is being expressed and is at the expected size of 250 kDa. Preliminary characterization on crude extract containing Mop has shown a Km and vmax value of 2453 uM and 0.025 uM min-1, respectively. Heme and pyrroloquinoline quinone can stimulate Mn(II) oxidizing activity, but hydrogen peroxide does not affect activity, despite the sequence similarity to animal heme peroxidase proteins. Research has been shown that calcium is essential for Mop activity. Purifying an active Mn(II) oxidizing protein will allow for a better understanding behind the enigmatic process of Mn(II) oxidation.

  5. Manganese(II) complexes with thiosemicarbazones as potential anti-Mycobacterium tuberculosis agents.

    PubMed

    Oliveira, Carolina G; da S Maia, Pedro Ivo; Souza, Paula C; Pavan, Fernando R; Leite, Clarice Q F; Viana, Rommel B; Batista, Alzir A; Nascimento, Otaciro R; Deflon, Victor M

    2014-03-01

    Through a systematic variation on the structure of a series of manganese complexes derived from 2-acetylpyridine-N(4)-R-thiosemicarbazones (Hatc-R), structural features have been investigated with the aim of obtaining complexes with potent anti-Mycobacterium tuberculosis activity. The analytical methods used for characterization included FTIR, EPR, UV-visible, elemental analysis, cyclic voltammetry, magnetic susceptibility measurement and single crystal X-ray diffractometry. Density functional theory (DFT) calculations were performed in order to evaluate the contribution of the thiosemicarbazonate ligands on the charge distribution of the complexes by changing the peripheral groups as well as to verify the Mn-donor atoms bond dissociation predisposition. The results obtained are consistent with the monoanionic N,N,S-tridentate coordination of the thiosemicarbazone ligands, resulting in octahedral complexes of the type [Mn(atc-R)2], paramagnetic in the extension of 5 unpaired electrons, whose EPR spectra are consistent for manganese(II). The electrochemical analyses show two nearly reversible processes, which are influenced by the peripheral substituent groups at the N4 position of the atc-R(1-) ligands. The minimal inhibitory concentration (MIC) of these compounds against M. tuberculosis as well as their in vitro cytotoxicity on VERO and J774A.1 cells (IC50) was determined in order to find their selectivity index (SI) (SI=IC50/MIC). The results evidenced that the compounds described here can be considered as promising anti-M. tuberculosis agents, with SI values comparable or better than some commercial drugs available for the tuberculosis treatment. © 2013.

  6. Synthesis, structure and some properties of a manganese(II) benzoate containing diimine

    NASA Astrophysics Data System (ADS)

    Paul, Pranajit; Roy, Subhadip; Sarkar, Sanjoy; Chowdhury, Shubhamoy; Purkayastha, R. N. Dutta; Raghavaiah, Pallepogu; McArdle, Patrick; Deb, Lokesh; Devi, Sarangthem Indira

    2015-12-01

    A new monomeric manganese(II) benzoate complex containing nitrogen donor 2,2‧-bipyridine, [Mn(OBz)2(bipy)(H2O)] (OBz = benzoate, bipy = 2,2‧-bipyridine) has been synthesized from aqueous methanol medium and characterized by analytical, spectroscopic and single crystal X-ray diffraction studies. The compound exhibits moderate to appreciable antimicrobial activity. The complex crystallizes in space group P21/n. Mn(II) atom is ligated by two N atoms of bipyridine, three O atoms from a monodentate and a bidentate benzoate ligand and a water molecule forming distorted octahedral structure. The coordinated water molecule forms intramolecular hydrogen bonds and links the monomer molecules into hydrogen bonded dimer. The hydrogen bonded dimers are involved in intermolecular C-H···O and π-π stacking interactions. Density functional theory (DFT) computation was carried out to compute the frequencies of relevant vibrational modes and electronic properties, the results are in compliance with the experimentally obtained structural and spectral data.

  7. Diphenyl Diselenide Protects Against Mortality, Locomotor Deficits and Oxidative Stress in Drosophila melanogaster Model of Manganese-Induced Neurotoxicity.

    PubMed

    Adedara, Isaac A; Abolaji, Amos O; Rocha, Joao B T; Farombi, Ebenezer O

    2016-06-01

    Several experimental and epidemiological reports have associated manganese exposure with induction of oxidative stress and locomotor dysfunctions. Diphenyl diselenide (DPDS) is widely reported to exhibit antioxidant, anti-inflammatory and neuroprotective effects in in vitro and in vivo studies via multiple biochemical mechanisms. The present study investigated the protective effect of DPDS on manganese-induced toxicity in Drosophila melanogaster. The flies were exposed, in a dietary regimen, to manganese alone (30 mmol per kg) or in combination with DPDS (10 and 20 µmol per kg) for 7 consecutive days. Exposure to manganese significantly (p < 0.05) increased flies mortality, whereas the survivors exhibited significant locomotor deficits with increased acetylcholinesterase (AChE) activity. However, dietary supplementation with DPDS caused a significant decrease in mortality, improvement in locomotor activity and restoration of AChE activity in manganese-exposed flies. Additionally, the significant decreases in the total thiol level, activities of catalase and glutathione-S-transferase were accompanied with significant increases in the generation of reactive oxygen and nitrogen species and thiobarbituric acid reactive substances in flies exposed to manganese alone. Dietary supplementation with DPDS significantly augmented the antioxidant status and prevented manganese-induced oxidative stress in the treated flies. Collectively, the present data highlight that DPDS may be a promising chemopreventive drug candidate against neurotoxicity resulting from acute manganese exposure.

  8. Chemoprotective role of quercetin in manganese-induced toxicity along the brain-pituitary-testicular axis in rats.

    PubMed

    Adedara, Isaac A; Subair, Temitayo I; Ego, Valerie C; Oyediran, Oluwasetemi; Farombi, Ebenezer O

    2017-02-01

    Reproductive dysfunction in response to manganese exposure has been reported in humans and animals. Quercetin, a bioflavonoid widely distributed in fruits, vegetables and beverages has been shown to possess antioxidant, anti-inflammatory and anti-apoptotic activities in different experimental model systems. However, there is dearth of scientific information on the influence of quercetin on manganese-induced reproductive toxicity. This study was designed to evaluate the influence of quercetin on manganese-induced functional alterations along the brain-pituitary- testicular axis in rats. Manganese was administered alone at 15 mg/kg body weight or orally co-treated with quercetin at 10 and 20 mg/kg body weight for 45 consecutive days. Results indicated that quercetin co-treatment significantly (p < 0.05) inhibited manganese-induced elevation in biomarkers of oxidative stress whereas it increased antioxidant enzymes activities and glutathione level in the brain, testes and epididymis of the treated rats. Furthermore, quercetin mediated suppression of inflammatory indices and caspase-3 activity was accompanied by preservation of histo-architectures of the brain, testes and epididymis in manganese-treated rats. The significant reversal of manganese-induced decreases in reproductive hormones (i.e. luteinizing hormone, follicle-stimulating hormone and testosterone) and testicular activities of acid phosphatase, alkaline phosphatase and lactate dehydrogenase by quercetin was complemented by an increase in sperm quality and quantity in the treated rats. Collectively, quercetin modulated manganese-induced toxicity along the brain-pituitary-testicular axis in rats via its intrinsic antioxidant, anti-inflammatory and anti-apoptotic activities, and may thus represent a potential pharmacological agent against manganese-induced male reproductive deficits in humans.

  9. Cloud point extraction, preconcentration and spectrophotometric determination of trace amount of manganese(II) in water and food samples.

    PubMed

    Gouda, Ayman A

    2014-10-15

    A new cloud point extraction (CPE) process using the nonionic surfactant Triton X-114 to extract manganese(II) from aqueous solution was investigated. The method is based on the complexation reaction of manganese(II) with 1,2,5,8-tetrahydroxyanthracene-9,10-dione (quinalizarin) in the presence of borate buffer at pH 8.5 and micelle-mediated extraction of the complex. The enriched analyte in the surfactant-rich phase was determined by spectrophotometry at 528nm. The optimal extraction and reaction conditions (e.g. pH, reagent and surfactant concentrations, temperature and centrifugation times) were evaluated and optimized. Under the optimized experimental conditions, the analytical characteristics of the method (e.g., limit of detection (LOD), linear range, preconcentration and improvement factors) were obtained. The proposed CPE method showed linear calibration within the range 5.0-200ngmL(-1) of manganese(II) and the limit of detection of the method was 0.8ngmL(-1) with an preconcentration factor of ∼50 when 25mL of sample solution was preconcentrated to 0.5mL. The relative standard deviation (RSD) and relative error were found to be 1.35% and 1.42%, respectively (CMn(II)=150ngmL(-1), n=6) for pure standard solutions. The interference effect of some cations and anions was also studied. In the presence of foreign ions, no significant interference was observed. The method was applied to the determination of manganese(II) in water and food samples with a recovery for the spiked samples in the range of 95.87-102.5%. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. Pathogenesis of Mortalin in Manganese-induced Parkinsonism

    NASA Astrophysics Data System (ADS)

    Cook, Travis J.

    Manganese (Mn) is an essential dietary micronutrient for which excessive exposure has long been known to be neurotoxic. Historically, short-term, high-intensity exposure in occupational settings was recognized to cause acute-onset parkinsonism (PS) termed manganism. Although modern day exposures are typically several orders of magnitude lower than those necessary to cause manganism, chronic, low-level exposures are not uncommon among a number of occupations and communities. Recent epidemiologic studies have demonstrated an association between Mn exposure and risk of PS, and in this regard Mn remains a public health concern. The work described here was designed to provide insight toward questions which remain with respect to Mn exposure and its toxic effect on the brain, and includes studies utilizing Mn exposed human populations and in vitro model systems to address these objectives. Blood plasma samples obtained from a cohort of welders, whose work is recognized as generating appreciable amounts of airborne Mn, and post-mortem brain tissue of Mn mine workers were both found to have discernable alterations related to the mitochondrial chaperone protein mortalin. Furthermore, in vitro studies demonstrated that reduced astroglial expression of mortalin confers neuronal susceptibility to toxicity elicited by low levels of Mn, possibly via mechanisms of endoplasmic reticulum and oxidative stress mediated by alpha-synuclein. Taken together, the results of these studies indicate that Mn exposures experienced by modern day populations are sufficient to cause biological alterations in humans that are potentially neurotoxic.

  11. Terphenyl substituted derivatives of manganese(II): distorted geometries and resistance to elimination.

    PubMed

    Ni, Chengbao; Fettinger, James C; Long, Gary J; Power, Philip P

    2010-11-28

    Reaction of {Li(THF)Ar'MnI(2)}(2) (Ar' = C(6)H(3)-2,6-(C(6)H(2)-2,6-(i)Pr(3))(2)) with LiAr', LiC≡CR (R = (t)Bu or Ph), or (C(6)H(2)-2,4,6-(i)Pr(3))MgBr(THF)(2) afforded the diaryl MnAr'(2) (1), the alkynyl salts Ar'Mn(C≡C(t)Bu)(4){Li(THF)}(3) (2) and Ar'Mn(C≡CPh)(3)Li(3)(THF)(Et(2)O)(2)(μ(3)-I) (3), and the manganate salt {Li(THF)}Ar'Mn(μ-I)(C(6)H(2)-2,4,6-(i)Pr(3)) (4), respectively. Complex 4 reacted with one equivalent of (C(6)H(2)-2,4,6-(i)Pr(3))MgBr(THF)(2) to afford the homoleptic dimer {Mn(C(6)H(2)-2,4,6-(i)Pr(3))(μ-C(6)H(2)-2,4,6-(i)Pr(3))}(2) (5), which resulted from the displacement of the bulkier Ar' ligand in preference to the halogen. The reaction of the more crowded {Li(THF)Ar*MnI(2)}(2) (Ar* = C(6)H(3)-2,6-(C(6)H(2)-2,4,6-(i)Pr(3))(2)) with Li(t)Bu gave complex Ar*Mn(t)Bu (6). Complex 1 is a rare monomeric homoleptic two-coordinate diaryl Mn(II) complex; while 6 displays no tendency to eliminate β-hydrogens from the (t)Bu group because of the stabilization supplied by Ar*. Compounds 2 and 3 have cubane frameworks, which are constructed from a manganese, three carbons from three acetylide ligands, three lithiums, each coordinated by a donor, plus either a carbon from a further acetylide ligand (2) or an iodide (3). The Mn(II) atom in 4 has an unusual distorted T-shaped geometry while the dimeric 5 features trigonal planar manganese coordination. The chloride substituted complex Li(2)(THF)(3){Ar'MnCl(2)}(2) (7), which has a structure very similar to that of {Li(THF)Ar'MnI(2)}(2), was also prepared for use as a possible starting material. However, its generally lower solubility rendered it less useful than the iodo salt. Complexes 1-7 were characterized by X-ray crystallography and UV-vis spectroscopy. Magnetic studies of 2-4 and 6 showed that they have 3d(5) high-spin configurations.

  12. Synthesis and evaluation of a high relaxivity manganese(II)-based MRI contrast agent.

    PubMed

    Troughton, Jeffrey S; Greenfield, Matthew T; Greenwood, Jaclyn M; Dumas, Stéphane; Wiethoff, Andrea J; Wang, Jufeng; Spiller, Marga; McMurry, Thomas J; Caravan, Peter

    2004-10-04

    The manganese(II) ion has many favorable properties that lead to its potential use as an MRI contrast agent: high spin number, long electronic relaxation time, labile water exchange. The present work describes the design, synthesis, and evaluation of a novel Mn(II) complex (MnL1) based on EDTA and also contains a moiety that noncovalently binds the complex to serum albumin, the same moiety used in the gadolinium based contrast agent MS-325. Ultrafiltration albumin binding measurements (0.1 mM, pH 7.4, 37 degrees C) indicated that the complex binds well to plasma proteins (rabbit: 96 +/- 2% bound, human: 93 +/- 2% bound), and most likely to serum albumin (rabbit: 89 +/- 2% bound, human 98 +/- 2% bound). Observed relaxivities (+/- 5%) of the complex were measured (20 MHz, 37 degrees C, 0.1 mM, pH 7.4) in HEPES buffer (r(1) = 5.8 mM(-)(1) s(-)(1)), rabbit plasma (r(1) = 51 mM(-)(1) s(-)(1)), human plasma (r(1) = 46 mM(-)(1) s(-)(1)), 4.5% rabbit serum albumin (r(1) = 47 mM(-)(1) s(-)(1)), and 4.5% human serum albumin (r(1) = 48 mM(-)(1) s(-)(1)). The water exchange rate was near optimal for an MRI contrast agent (k(298) = 2.3 +/- 0.9 x 10(8) s(-)(1)). Variable temperature NMRD profiles indicated that the high relaxivity was due to slow tumbling of the albumin-bound complex and fast exchange of the inner sphere water. The concept of a high relaxivity Mn(II)-based contrast agent was validated by imaging at 1.5 T. In a rabbit model of carotid artery injury, MnL1 clearly delineated both arteries and veins while also distinguishing between healthy tissue and regions of vessel damage.

  13. Simulation, planning, and optimization of redox processes involving the catalytic disproportionation of H/sub 2/O/sub 2/ by manganese(II) complexes with glycine

    SciTech Connect

    Batyr, D.G.; Isak, V.G.; Kil'mininov, S.V.; Kharitonov, Yu.Ya.

    1987-11-01

    The applicability of the use of a method for the simulation, planning, and optimization of chemical processes has been demonstrated in the example case of the manganese(II)-glycine-hydrogen peroxide redox system. Theoretical calculations based on experimental data have made it possible to present a mechanism for the catalase-mediated decomposition of hydrogen peroxide in the presence of coordination compounds of manganese(II) with glycine.

  14. Statics of molybdenum sorption from manganese(II) sulfate solutions on porous and macronetwork anion-exchange resin AN-108

    SciTech Connect

    Kholmogorov, A.G.; Kononova, O.N.; Pashkov, G.L.

    1994-11-20

    The statics have been considered of the ion-exchange equilibrium in the system R{sub 2}SO{sub 4}-MnSO{sub 4}-H{sub 2}SO{sub 4}-Mo(VI)-H{sub 2}O in recovery of molybdenum(VI) ions from sulfate solutions of manganese(II) in relation to the sulfuric acid concentration, physical and chemical structure of the ion-exchange resin, and solution temperatures.

  15. Manganese induces endoplasmic reticulum (ER) stress and activates multiple caspases in nigral dopaminergic neuronal cells, SN4741.

    PubMed

    Chun, H S; Lee, H; Son, J H

    2001-12-04

    Chronic exposure to manganese causes Parkinson's disease (PD)-like clinical symptoms (Neurotoxicology 5 (1984) 13; Arch. Neurol. 46 (1989) 1104; Neurology 56 (2001) 4). Occupational exposure to manganese is proposed as a risk factor in specific cases of idiopathic PD (Neurology 56 (2001) 8). We have investigated the mechanism of manganese neurotoxicity in nigral dopaminergic (DA) neurons using the DA cell line, SN4741 (J. Neurosci. 19 (1999) 10). Manganese treatment elicited endoplasmic reticulum (ER) stress responses, such as an increased level of the ER chaperone BiP, and simultaneously activated the ER resident caspase-12. Peak activation of other major initiator caspases-like activities, such as caspase-1, -8 and -9, ensued, resulting in activation of caspase-3-like activity during manganese-induced DA cell death. The neurotoxic cell death induced by manganese was significantly reduced in the Bcl-2-overexpressing DA cell lines. Our findings suggest that manganese-induced neurotoxicity is mediated in part by ER stress and considerably ameliorated by Bcl-2 overexpression in DA cells.

  16. Mn(II) removal from groundwater with manganese oxide-coated filter media.

    PubMed

    Piispanen, Jutta K; Sallanko, Jarmo T

    2010-11-01

    Removing soluble manganese from groundwater requires a strong chemical oxidant, such as ozone or potassium permanganate, or raising the pH to alkaline value (over pH 9). Biological or adsorption processes can also be applied. Filter media naturally or industrially coated with manganese oxide are effective in adsorptive manganese removal. In this work, a layer of commercial manganese oxide coated medium was added to the top of an experimental sand/anthracite filter column to improve manganese removal. The coated layer was ca 28 cm thick (20% of the total filter depth) and the sand layer was 110 cm thick. The coated layer enhanced the manganese removal markedly. Manganese removal increased by over 91%, and < 0.02 mg/L of manganese remained in the treated water. Also iron removal was enhanced. Filters with added coated layer recovered faster than reference filter from filter backwashes. Sodium hypochlorite feed, which was tested in regeneration of the filter medium, had a slight negative effect on the filter performance.

  17. Synthesis, structure determination and 3D molecular modeling of some novel manganese(II) complexes

    NASA Astrophysics Data System (ADS)

    Hari Kumaran Nair, M. L.; Lalitha, K. P.

    2013-06-01

    Some novel manganese(II) complexes with the ligand (z)-4-((2-hydroxy-4-methoxyphenyl)diazenyl)-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one, MPAAP, 3-methoxy phenol azoantipyrine, L1, having the formulae [Mn(L1)2(X)2], [Mn(L1)2(Y)2], where X = Cl- / Br-; Y = NCS- were synthesized and characterized by elemental analysis, molar conductance and magnetic susceptibility measurements, spectral (IR, UV-Visible, EPR, FAB mass) studies, thermogravimetric analysis, powder XRD and cyclic voltammetric studies and by SEM image. An octahedral structure is tentatively proposed for the complexes with respect to the above studies. The [Mn(L1)2(Y)2] was subjected to γ-ray irradiation and the internal changes accompanied were evaluated. The energy minimized configuration of the complex [Mn(L1)2(Y)2] was made with CHEM Bio 3D Ultra 11.0 and the respective parameters are computed. The ligand and its complex [Mn(L1)2(Y)2] were screened for their possible antimicrobial activities.

  18. Colorimetric detection of manganese(II) ions using gold/dopa nanoparticles.

    PubMed

    Narayanan, Kannan Badri; Park, Hyun Ho

    2014-10-15

    We report here a one-pot, greener, eco-friendly strategy for the synthesis of gold nanoparticles using L-dopa. The as-prepared dopa-functionalized gold nanoparticles (AuNPs/dopa) can detect low concentrations of manganese(II) metal ions in aqueous solution. The binding forces between dopa and Mn(2+) ions cause dopa-functionalized gold nanoparticles to come closer together, decreasing the interparticle distance and aggregating it with a change in color of colloidal solution from red to purplish-blue. Dynamic light scattering (DLS) analysis showed a decreased surface charge on the surface of gold nanoparticles when exposed to Mn(2+) ions, which caused cross-linking aggregation. Transmission electron microscopic (TEM) images also revealed the aggregation of gold nanoparticles with the addition of Mn(2+) ions. The extinction ratio of absorbance at 700-550nm (A700/A550) was linear against the concentration of [Mn(2+)] ions. Thus, the optical absorption spectra of gold colloidal solution before and after the addition of Mn(2+) ions reveal the concentration of Mn(2+) ions in solution.

  19. Colorimetric detection of manganese(II) ions using gold/dopa nanoparticles

    NASA Astrophysics Data System (ADS)

    Narayanan, Kannan Badri; Park, Hyun Ho

    2014-10-01

    We report here a one-pot, greener, eco-friendly strategy for the synthesis of gold nanoparticles using L-dopa. The as-prepared dopa-functionalized gold nanoparticles (AuNPs/dopa) can detect low concentrations of manganese(II) metal ions in aqueous solution. The binding forces between dopa and Mn2+ ions cause dopa-functionalized gold nanoparticles to come closer together, decreasing the interparticle distance and aggregating it with a change in color of colloidal solution from red to purplish-blue. Dynamic light scattering (DLS) analysis showed a decreased surface charge on the surface of gold nanoparticles when exposed to Mn2+ ions, which caused cross-linking aggregation. Transmission electron microscopic (TEM) images also revealed the aggregation of gold nanoparticles with the addition of Mn2+ ions. The extinction ratio of absorbance at 700-550 nm (A700/A550) was linear against the concentration of [Mn2+] ions. Thus, the optical absorption spectra of gold colloidal solution before and after the addition of Mn2+ ions reveal the concentration of Mn2+ ions in solution.

  20. Determination of proteins with tetracarboxy manganese(II) phthalocyanine by resonance light scattering technique.

    PubMed

    Tang, Ning-Li; Peng, Jin-Yun

    2008-12-15

    A novel method for the determination of proteins by using tetracarboxy manganese(II) phthalocyanine (MnC4Pc) as a resonance light scattering (RLS) probe has been developed. At pH 3.0 Britton-Robinson (B-R) buffer solution, the RLS intensity of MnC4Pc at 385 nm is greatly enhanced in the presence of proteins. The effects of pH, reaction time, concentration of MnC4Pc and interfering substances on the enhanced RLS intensity are investigated, respectively. Under optimal conditions, the linear ranges of the calibration curves are 0-2.00 microg mL(-1) for bovine serum albumin (BSA) and human serum albumin (HSA), 0.0-1.75 microg mL(-1) for human-IgG and ovalbumin, with a detection limit of 16.37 ng mL(-1) BSA, 17.62 ng mL(-1) HSA, 19.41 ng mL(-1) human-IgG and 20.72 ng mL(-1) ovalbumin. The method has been applied to the determination of total proteins in human serum samples collected from a hospital and the results are in good agreement with those reported by the hospital.

  1. Steric interaction of solvation and sterically enhanced halogeno complexation of manganese(II), cobalt(II) and nickel(II) ions in N,N-dimethylacetamide

    SciTech Connect

    Koide, Makoto; Suzuki, Honoh; Ishiguro, Shin-ichi

    1994-12-01

    The complexation of manganese(II), cobalt(II) and nickel(II) with bromide ions has been studied in N,N-dimethylacetamide (DMA) by calorimetry and spectrophotometry. The formation of [MBr]{sup +}, [MBr{sub 2}] and [MBr{sub 3}]{sup -} (M = Mn, Co, Ni) was revealed in all the metal systems. Interestingly, the complexation is significantly enhanced in DMA over N,N-dimethylformamide (DMF). This is unusual because physicochemical properties of DMA and DMF as solvent are similar. Furthermore, extracted electronic spectra of individual complexes of Ni{sup II} suggested the presence of a geometry equilibrium, [NiBr(DMA){sub 5}]{sup +} = [NiBr(DMA){sub 4}]{sup +} + DMA, in DMA. A similar geometry equilibrium is also suggested, [NiBr{sub 2}(DMA){sub 3}] = [NiBr{sub 2}(DMA){sub 2}] + DMA. Such geometry equilibria were not observed in DMF. With regard to cobalt(II), electronic spectra show the presence of the four-coordinated [CoBr(DMA){sub 3}]{sup +} complex in DMA, unlike the six-coordinated [CoBr(DMF){sub 5}]{sup +} one in DMF. These facts suggest that a specific strong steric interaction operates between coordinating solvent molecules, which plays a key role in the complexation behavior of the divalent transition metal ions in DMA.

  2. 24-epibrassinolide mitigates the adverse effects of manganese induced toxicity through improved antioxidant system and photosynthetic attributes in Brassica juncea.

    PubMed

    Fariduddin, Qazi; Ahmed, Mumtaz; Mir, Bilal A; Yusuf, Mohammad; Khan, Tanveer A

    2015-08-01

    The objective of this study was to establish relationship between manganese-induced toxicity and antioxidant system response in Brassica juncea plants and also to investigate whether brassinosteroids activate antioxidant system to confer tolerance to the plants affected with manganese induced oxidative stress. Brassica juncea plants were administered with 3, 6, or 9 mM manganese at 10-day stage for 3 days. At 31-day stage, the seedlings were sprayed with deionized water (control) or 10(-8) M of 24-epibrassinolide, and plants were harvested at 45-day stage to assess growth, leaf gas-exchange traits, and biochemical parameters. The manganese treatments diminished growth along with photosynthetic attributes and carbonic anhydrase activity in the concentration-dependent manner, whereas it enhanced lipid peroxidation, electrolyte leakage, accumulation of H2O2 as well as proline, and various antioxidant enzymes in the leaves of Brassica juncea which were more pronounced at higher concentrations of manganese. However, the follow-up application of 24-epibrassinolide to the manganese stressed plants improved growth, water relations, and photosynthesis and further enhanced the various antioxidant enzymes viz. catalase, peroxidase, and superoxide dismutase and content of proline. The elevated level of antioxidant enzymes as well as proline could have conferred tolerance to the manganese-stressed plants resulting in improved growth and photosynthetic attributes.

  3. Austenite Stability Effects on Tensile Behavior of Manganese-Enriched-Austenite Transformation-Induced Plasticity Steel

    NASA Astrophysics Data System (ADS)

    Gibbs, P. J.; de Moor, E.; Merwin, M. J.; Clausen, B.; Speer, J. G.; Matlock, D. K.

    2011-12-01

    Manganese enrichment of austenite during prolonged intercritical annealing was used to produce a family of transformation-induced plasticity (TRIP) steels with varying retained austenite contents. Cold-rolled 0.1C-7.1Mn steel was annealed at incremental temperatures between 848 K and 948 K (575 °C and 675 °C) for 1 week to enrich austenite in manganese. The resulting microstructures are comprised of varying fractions of intercritical ferrite, martensite, and retained austenite. Tensile behavior is dependent on annealing temperature and ranged from a low strain-hardening "flat" curve to high strength and ductility conditions that display positive strain hardening over a range of strain levels. The mechanical stability of austenite was measured using in-situ neutron diffraction and was shown to depend significantly on annealing temperature. Variations in austenite stability between annealing conditions help explain the observed strain hardening behaviors.

  4. Analysis of Manganese in Soil Using Laser-Induced Breakdown Spectroscopy

    NASA Astrophysics Data System (ADS)

    Yongcheng, J.; Jiang, H.; Benchi, J.; Dong, L.

    2017-03-01

    Laser-induced breakdown spectroscopy (LIBS) has been applied to measure spectral characteristics and to perform quantitative analysis of the concentration of manganese in soil, an issue of great concern for precision agriculture. For the analysis, soil samples were compressed into pellets and a pulsed Nd:YAG laser was employed to produce the plasma in air at atmospheric pressure. Using this approach, we analyzed the time evolution of spectral characteristics and their dependence on the laser pulse energy. A calibration curve was constructed using reference sandy soil samples collected from a farm. An internal standard curve was used to improve the accuracy of the LIBS metrology for soil analyses. The results of this analysis demonstrated the usefulness of this method for analyzing the concentration of manganese in soil.

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

    PubMed

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

    2015-06-12

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

  6. Apoptosis Induced by Manganese on Neuronal SK-N-MC Cell Line: Endoplasmic Reticulum (ER) Stress and Mitochondria Dysfunction

    PubMed Central

    Yoon, Hyonok; Kim, Do-Sung; Lee, Geum-Hwa; Kim, Kee-Won; Kim, Hyung-Ryong

    2011-01-01

    Objectives Manganese chloride (MnCl2) is one of heavy metals for causing neurogenerative dysfunction like Manganism. The purpose of this study was to determine the acute toxicity of MnCl2 using different times and various concentrations including whether manganese toxicity may involve in two intrinsic pathways, endoplasmic reticulum (ER) stress and mitochondria dysfunction and lead to neuronal apoptosis mediated by organelle disorders in neuroblastoma cell line SK-N-MC. Methods In the acute toxicity test, five concentrations (200, 400, 600, 800, 1,000 uM) of MnCl2 with 3, 6, 12, 24, 48 hours exposure were selected to analyze cell viability. In addition, to better understand their toxicity, acute toxicity was examined with 1,000 uM MnCl2 for 24 hours exposure via reactive oxygen species (ROS), mitochondria membrane potential, western blotting and mitochondrial complex activities. Results Our results showed that both increments of dose and time prompt the increments in the number of dead cells. Cells treated by 1,000 µM MnCl2 activated 265% (±8.1) caspase-3 compared to control cell. MnCl2 induced intracellular ROS produced 168% (±2.3%) compared to that of the control cells and MnCl2 induced neurotoxicity significantly dissipated 48.9% of mitochondria membrane potential compared to the control cells. Conclusions This study indicated that MnCl2 induced apoptosis via ER stress and mitochondria dysfunction. In addition, MnCl2 affected only complex I except complex II, III or IV activities. PMID:22232721

  7. New manganese(II) and nickel(II) coordination compounds with N,O-polydentate ligands obtained from pyridoxal and tripodal units

    NASA Astrophysics Data System (ADS)

    Ebani, Patrícia Regina; Fontana, Liniquer Andre; Campos, Patrick Teixeira; Rosso, Eduardo F.; Piquini, Paulo C.; Iglesias, Bernardo Almeida; Back, Davi Fernando

    2016-09-01

    We have reported the synthesis involving the condensation of pyridoxal with tris(2-aminoethyl)amine obtained a tripodal ligand, as well as its subsequent complexation with the manganese(II) and nickel(II) ions. The structural analysis revealed, in the case of complex 1, the formation of a monomeric complex with Mn(II) species. In the complex 2, with Ni(II) metal ion, we describe the probable mechanism for the formation of hemiacetal in these complexes. Only the complex 1 catalyze the dismutation of superoxide efficiently with IC50 equal to 3.38 μM, evaluated through the nitro blue tetrazolium photoreduction inhibition superoxide dismutase assay, in aqueous solution of pH 7.8. Density functional theory calculations are done to characterize and compare the molecular frontier orbitals of the Mn(II) and Ni(II) complexes.

  8. A simple and effective catalytic system for epoxidation of aliphatic terminal alkenes with manganese(II) as the catalyst.

    PubMed

    Ho, Kam-Piu; Wong, Wing-Leung; Lam, Kin-Ming; Lai, Cheuk-Piu; Chan, Tak Hang; Wong, Kwok-Yin

    2008-01-01

    A simple catalytic system that uses commercially available manganese(II) perchlorate as the catalyst and peracetic acid as the oxidant is found to be very effective in the epoxidation of aliphatic terminal alkenes with high product selectivity at ambient temperature. Many terminal alkenes are epoxidised efficiently on a gram scale in less than an hour to give excellent yields of isolated product (>90 %) of epoxides in high purity. Kinetic studies with some C9-alkenes show that the catalytic system is more efficient in epoxidising terminal alkenes than internal alkenes, which is contrary to most commonly known epoxidation systems. The reaction rate for epoxidation decreases in the order: 1-nonene>cis-3-nonene>trans-3-nonene. ESI-MS and EPR spectroscopic studies suggest that the active form of the catalyst is a high-valent oligonuclear manganese species, which probably functions as the oxygen atom-transfer agent in the epoxidation reaction.

  9. Impact of Mn(II)-Manganese Oxide Reactions on Ni and Zn Speciation.

    PubMed

    Hinkle, Margaret A G; Dye, Katherine G; Catalano, Jeffrey G

    2017-03-21

    Layered Mn oxide minerals (phyllomanganates) often control trace metal fate in natural systems. The strong uptake of metals such as Ni and Zn by phyllomanganates results from adsorption on or incorporation into vacancy sites. Mn(II) also binds to vacancies and subsequent comproportionation with structural Mn(IV) may alter sheet structures by forming larger and distorted Mn(III)O6 octahedra. Such Mn(II)-phyllomanganate reactions may thus alter metal uptake by blocking key reactive sites. Here we investigate the effect of Mn(II) on Ni and Zn binding to phyllomanganates of varying initial vacancy content (δ-MnO2, hexagonal birnessite, and triclinic birnessite) at pH 4 and 7 under anaerobic conditions. Dissolved Mn(II) decreases macroscopic Ni and Zn uptake at pH 4 but not pH 7. Extended X-ray absorption fine structure spectroscopy demonstrates that decreased uptake at pH 4 corresponds with altered Ni and Zn adsorption mechanisms. These metals transition from binding in the interlayer to sheet edges, with Zn increasing its tetrahedrally coordinated fraction. These effects on metal uptake and binding correlate with Mn(II)-induced structural changes, which are more substantial at pH 4 than 7. Through these structural effects and the pH-dependence of Mn(II)-metal competitive adsorption, system pH largely controls metal binding to phyllomanganates in the presence of dissolved Mn(II).

  10. Distribution of manganese species in an oxidative dimerization reaction of a bis-terpyridine mononuclear manganese (II) complex and their heterogeneous water oxidation activities.

    PubMed

    Takahashi, Kosuke; Sato, Taisei; Yamazaki, Hirosato; Yagi, Masayuki

    2015-11-01

    Heterogeneous water oxidation catalyses were studied as a synthetic model of oxygen evolving complex (OEC) in photosynthesis using mica adsorbing various manganese species. Distribution of manganese species formed in the oxidative dimerization reaction of [Mn(II)(terpy)2](2+) (terpy=2,2':6',2″-terpyridine) (1') with various oxidants in water was revealed. 1' was stoichiometrically oxidized to form di-μ-oxo dinuclear manganese complex, [(OH2)(terpy)Mn(III)(μ-O)2Mn(IV)(terpy)(OH2)](3+) (1) by KMnO4 as an oxidant. When Oxone and Ce(IV) oxidants were used, the further oxidation of 1 to [(OH2)(terpy)Mn(IV)(μ-O)2Mn(IV)(terpy)(OH2)](4+) (2) was observed after the oxidative dimerization reaction of 1'. The mica adsorbates with various composition of 1', 1 and 2 were prepared by adding mica suspension to the various oxidant-treated solutions followed by filtration. The heterogeneous water oxidation catalysis by the mica adsorbates was examined using a Ce(IV) oxidant. The observed catalytic activity of the mica adsorbates corresponded to a content of 1 (1ads) adsorbed on mica for KMnO4- and Oxone-treated systems, indicating that 1' (1'ads) and 2 (2ads) adsorbed on mica do not work for the catalysis. The kinetic analysis suggested that 1ads works for the catalysis through cooperation with adjacent 1ads or 2ads, meaning that 2ads assists the cooperative catalysis by 1ads though 2ads is not able to work for the catalysis alone. For the Ce(IV)-treated system, O2 evolution was hardly observed although the sufficient amount of 1ads was contained in the mica adsorbates. This was explained by the impeded penetration of Ce(IV) ions (as an oxidant for water oxidation) into mica by Ce(3+) cations (generated in oxidative dimerization of 1') co-adsorbed with 1ads.

  11. Uraninite oxidation and dissolution induced by manganese oxide: A redox reaction between two insoluble minerals

    NASA Astrophysics Data System (ADS)

    Wang, Zimeng; Lee, Sung-Woo; Kapoor, Pratyul; Tebo, Bradley M.; Giammar, Daniel E.

    2013-01-01

    The longevity of subsurface U(IV) produced by reduction of U(VI) during in situ bioremediation can be limited by reoxidation to more mobile U(VI) species. Coupling of the biogeochemical cycles of U and Mn may affect the fate and transport of uranium. Manganese oxides can act as a powerful oxidant that accelerates the oxidative dissolution of UO2. This study investigated the physical and chemical factors controlling the interaction between UO2 and MnO2, which are both poorly soluble minerals. A multi-chamber reactor with a permeable membrane was used to eliminate direct contact of the two minerals while still allowing transport of aqueous species. The oxidation of UO2 was not significantly enhanced by MnO2 if the two solids were physically separated. Complete mixing of MnO2 with UO2 led to a much greater extent and rate of U oxidation. When direct contact is not possible, the reaction slowly progresses through release of soluble U(IV) with its adsorption and oxidation on MnO2. Continuously-stirred tank reactors (CSTRs) were used to quantify the steady-state rates of UO2 dissolution induced by MnO2. MnO2 dramatically promoted UO2 dissolution, but the degree of promotion leveled off once the MnO2:UO2 ratio exceeded a critical value. Substantial amounts of U(VI) and Mn(II) were retained on MnO2 surfaces. The total production of Mn(II) was less than that of U(VI), indicating that the fate of Mn products and their impact on UO2-MnO2 reaction kinetics were complicated and may involve formation of Mn(III) phases. At higher dissolved inorganic carbon concentrations, UO2 oxidation by MnO2 was faster and less U(VI) was adsorbed to MnO2. Such an inverse relationship suggested that U(VI) may passivate MnO2 surfaces. A conceptual model was developed to describe the oxidation rate of UO2 by MnO2. This model is potentially applicable to a broad range of water chemistry conditions and is relevant to other environmental redox processes involving two poorly soluble minerals.

  12. Excess manganese differentially inhibits photosystem I versus II in Arabidopsis thaliana.

    PubMed

    Millaleo, R; Reyes-Díaz, M; Alberdi, M; Ivanov, A G; Krol, M; Hüner, N P A

    2013-01-01

    The effects of exposure to increasing manganese concentrations (50-1500 µM) from the start of the experiment on the functional performance of photosystem II (PSII) and photosystem I (PSI) and photosynthetic apparatus composition of Arabidopsis thaliana were compared. In agreement with earlier studies, excess Mn caused minimal changes in the PSII photochemical efficiency measured as F(v)/F(m), although the characteristic peak temperature of the S(2/3)Q(B) (-) charge recombinations was shifted to lower temperatures at the highest Mn concentration. SDS-PAGE and immunoblot analyses also did not exhibit any significant change in the relative abundance of PSII-associated polypeptides: PSII reaction centre protein D1, Lhcb1 (major light-harvesting protein of LHCII complex), and PsbO (OEC33, a 33 kDa protein of the oxygen-evolving complex). In addition, the abundance of Rubisco also did not change with Mn treatments. However, plants grown under excess Mn exhibited increased susceptibility to PSII photoinhibition. In contrast, in vivo measurements of the redox transients of PSI reaction centre (P700) showed a considerable gradual decrease in the extent of P700 photooxidation (P700(+)) under increased Mn concentrations compared to control. This was accompanied by a slower rate of P700(+) re-reduction indicating a downregulation of the PSI-dependent cyclic electron flow. The abundance of PSI reaction centre polypeptides (PsaA and PsaB) in plants under the highest Mn concentration was also significantly lower compared to the control. The results demonstrate for the first time that PSI is the major target of Mn toxicity within the photosynthetic apparatus of Arabidopsis plants. The possible involvement mechanisms of Mn toxicity targeting specifically PSI are discussed.

  13. Excess manganese differentially inhibits photosystem I versus II in Arabidopsis thaliana

    PubMed Central

    Alberdi, M.

    2013-01-01

    The effects of exposure to increasing manganese concentrations (50–1500 µM) from the start of the experiment on the functional performance of photosystem II (PSII) and photosystem I (PSI) and photosynthetic apparatus composition of Arabidopsis thaliana were compared. In agreement with earlier studies, excess Mn caused minimal changes in the PSII photochemical efficiency measured as Fv/Fm, although the characteristic peak temperature of the S2/3QB – charge recombinations was shifted to lower temperatures at the highest Mn concentration. SDS-PAGE and immunoblot analyses also did not exhibit any significant change in the relative abundance of PSII-associated polypeptides: PSII reaction centre protein D1, Lhcb1 (major light-harvesting protein of LHCII complex), and PsbO (OEC33, a 33kDa protein of the oxygen-evolving complex). In addition, the abundance of Rubisco also did not change with Mn treatments. However, plants grown under excess Mn exhibited increased susceptibility to PSII photoinhibition. In contrast, in vivo measurements of the redox transients of PSI reaction centre (P700) showed a considerable gradual decrease in the extent of P700 photooxidation (P700+) under increased Mn concentrations compared to control. This was accompanied by a slower rate of P700+ re-reduction indicating a downregulation of the PSI-dependent cyclic electron flow. The abundance of PSI reaction centre polypeptides (PsaA and PsaB) in plants under the highest Mn concentration was also significantly lower compared to the control. The results demonstrate for the first time that PSI is the major target of Mn toxicity within the photosynthetic apparatus of Arabidopsis plants. The possible involvement mechanisms of Mn toxicity targeting specifically PSI are discussed. PMID:23183256

  14. Complex of manganese (II) with curcumin: Spectroscopic characterization, DFT study, model-based analysis and antiradical activity

    NASA Astrophysics Data System (ADS)

    Gorgannezhad, Lena; Dehghan, Gholamreza; Ebrahimipour, S. Yousef; Naseri, Abdolhossein; Nazhad Dolatabadi, Jafar Ezzati

    2016-04-01

    The complex formation between curcumin (Cur) and Manganese (II) chloride tetrahydrate (MnCl2.4H2O) was studied by UV-Vis and IR spectroscopy. Spectroscopic data suggest that Cur can chelate Manganese cations. A simple multi-wavelength model-based method was used to define stability constant for complexation reaction regardless of the spectra overlapping of components. Also, pure spectra and concentration profiles of all components were extracted using this method. Density functional theory (DFT) was also used to view insight into complexation mechanism. Antioxidant activity of Cur and Cur-Mn(II) complex was evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging method. Bond dissociation energy (BDE), the highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO) and Molecular electrostatic potential (MEP) of Cur and the complex also were calculated at PW91/TZ2P level of theory using ADF 2009.01 package. The experimental results show that Cur has a higher DPPH radical scavenging activity than Cur-Mn(II). This observation is theoretically justified by means of lower BDE and higher HOMO and LUMO energy values of Cur ligand as compared with those of Cur-Mn(II) complex.

  15. Potential of chaotic chemical systems in nanotrace analysis based on the Belousov-Zhabotinskii reaction (BrO(-)(3)-malonic acid-ferroin). Determination of manganese(II).

    PubMed

    Yatsimirskii, K B; Strizhak, P E; Ivaschenko, T S

    1993-08-01

    A new method for the determination of trace amounts of manganese(II) in aqueous solutions by its affect on some types of the chaotic regimes in the Belousov-Zhabotinskii reaction has been proposed. The method is based on the high sensitivity of some types of chaotic regimes of the BZ reaction to small perturbations of initial conditions (e.g., low concentrations of some metal ions). The experimentally obtained detection limit for manganese is 3 pg/ml.

  16. Manganese(II,III) Oxyborate, Mn 2OBO 3: A Distorted Homometallic Warwickite—Synthesis, Crystal Structure, Band Calculations, and Magnetic Susceptibility

    NASA Astrophysics Data System (ADS)

    Norrestam, R.; Kritikos, M.; Sjödin, A.

    1995-02-01

    The manganese(II,III) oxyborate with the composition Mn2OBO3 has been synthesized by high-temperature techniques. X-ray studies show that crystals of the specimen, grown with borax as flux, are monoclinic, with space group P21/n, = 9.2866(7), b = 9.5333(10), c = 3.2438(3) Å, and β = 90.757(7)°. A model of the crystal structure has been refined with the 2064 most significant (l ≥ 5 · σ1) X-ray reflections with sin(θ)/λ ≤ 1.08 Å-1 to R = 0.40. The structure of Mn2OBO3 can be considered to be a distorted modification of the orthorhombic warwickite structure. The distortions, apparently caused by Jahn-Teller effects induced by the Mn3+ ions, remove the mirror symmetry of the parent undistorted warwickite. As a consequence, the space group symmetry is lowered from Pnam to one of its subgroups, P21/n. The structural results as well as the measured magnetic susceptibilities indicate high-spin manganese ions. The magnetic susceptibilities in the temperature region 110-300 K follow the Curie-Weiss law. The Weiss constant of -132(1) K indicates an antiferromagnetic ordering at low temperature. The bond distances and calculated bond valence sums indicate that the trivalent manganese ions are located in the two inner columns of the four-octahedra-wide walls. This metal charge distribution is supported by extended Hückel band calculations on some homometallic warwickites. The difference in metal coordination around one of the borate oxygen atoms is reflected by a significant deviation of the borate group geometry from the ideal trigonal symmetry.

  17. The interaction of manganese nanoparticles with PC-12 cells induces dopamine depletion.

    PubMed

    Hussain, Saber M; Javorina, Amanda K; Schrand, Amanda M; Duhart, Helen M; Ali, Syed F; Schlager, John J

    2006-08-01

    This investigation was designed to determine whether nano-sized manganese oxide (Mn-40 nm) particles would induce dopamine (DA) depletion in a cultured neuronal phenotype, PC-12 cells, similar to free ionic manganese (Mn(2+)). Cells were exposed to Mn-40 nm, Mn(2+) (acetate), or known cytotoxic silver nanoparticles (Ag-15 nm) for 24 h. Phase-contrast microscopy studies show that Mn-40 nm or Mn(2+) exposure did not greatly change morphology of PC-12 cells. However, Ag-15 nm and AgNO(3) produce cell shrinkage and irregular membrane borders compared to control cells. Further microscopic studies at higher resolution demonstrated that Mn-40 nm nanoparticles and agglomerates were effectively internalized by PC-12 cells. Mitochondrial reduction activity, a sensitive measure of particle and metal cytotoxicity, showed only moderate toxicity for Mn-40 nm compared to similar Ag-15 nm and Mn(2+) doses. Mn-40 nm and Mn(2+) dose dependently depleted DA and its metabolites, dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), while Ag-15 nm only significantly reduced DA and DOPAC at concentrations of 50 mug/ml. Therefore, the DA depletion of Mn-40 nm was most similar to Mn(2+), which is known to induce concentration-dependent DA depletion. There was a significant increase (> 10-fold) in reactive oxygen species (ROS) with Mn-40 nm exposure, suggesting that increased ROS levels may participate in DA depletion. These results clearly demonstrate that nanoscale manganese can deplete DA, DOPAC, and HVA in a dose-dependent manner. Further study is required to evaluate the specific intracellular distribution of Mn-40 nm nanoparticles, metal dissolution rates in cells and cellular matrices, if DA depletion is induced in vivo, and the propensity of Mn nanoparticles to cross the blood-brain barrier or be selectively uptaken by nasal epithelium.

  18. Role of transcription factor yin yang 1 in manganese-induced reduction of astrocytic glutamate transporters: Putative mechanism for manganese-induced neurotoxicity.

    PubMed

    Karki, Pratap; Smith, Keisha; Johnson, James; Aschner, Michael; Lee, Eunsook

    2015-09-01

    Astrocytes are the most abundant non-neuronal glial cells in the brain. Once relegated to a mere supportive role for neurons, contemporary dogmas ascribe multiple active roles for these cells in central nervous system (CNS) function, including maintenance of optimal glutamate levels in synapses. Regulation of glutamate levels in the synaptic cleft is crucial for preventing excitotoxic neuronal injury. Glutamate levels are regulated predominantly by two astrocytic glutamate transporters, glutamate transporter 1 (GLT-1) and glutamate aspartate transporter (GLAST). Indeed, the dysregulation of these transporters has been linked to several neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS), Alzheimer's disease (AD) and Parkinson's disease (PD), as well as manganism, which is caused by overexposure to the trace metal, manganese (Mn). Although Mn is an essential trace element, its excessive accumulation in the brain as a result of chronic occupational or environmental exposures induces a neurological disorder referred to as manganism, which shares common pathological features with Parkinsonism. Mn decreases the expression and function of both GLAST and GLT-1. Astrocytes are commonly targeted by Mn, and thus reduction in astrocytic glutamate transporter function represents a critical mechanism of Mn-induced neurotoxicity. In this review, we will discuss the role of astrocytic glutamate transporters in neurodegenerative diseases and Mn-induced neurotoxicity.

  19. Role of transcription factor yin yang 1 in manganese-induced reduction of astrocytic glutamate transporters: putative mechanism for manganese-induced neurotoxicity

    PubMed Central

    Karki, Pratap; Smith, Keisha; Johnson, James; Aschner, Michael; Lee, Eunsook

    2014-01-01

    Astrocytes are the most abundant non-neuronal glial cells in the brain. Once relegated to a mere supportive role for neurons, contemporary dogmas ascribe multiple active roles for these cells in central nervous system (CNS) function, including maintenance of optimal glutamate levels in synapses. Regulation of glutamate levels in the synaptic cleft is crucial for preventing excitotoxic neuronal injury. Glutamate levels are regulated predominantly by two astrocytic glutamate transporters, glutamate transporter 1 (GLT-1) and glutamate aspartate transporter (GLAST). Indeed, the dysregulation of these transporters has been linked to several neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS), Alzheimer's disease (AD) and Parkinson's disease (PD), as well as manganism, which is caused by overexposure to the trace metal, manganese (Mn). Although Mn is an essential trace element, its excessive accumulation in the brain as a result of chronic occupational or environmental exposures induces a neurological disorder referred to as manganism, which shares common pathological features with Parkinsonism. Mn decreases the expression and function of both GLAST and GLT-1.Astrocytes are commonly targeted by Mn, and thus reduction in astrocytic glutamate transporter function represents a critical mechanism of Mn-induced neurotoxicity. In this review, we will discuss the role of astrocytic glutamate transporters in neurodegenerative diseases and Mn-induced neurotoxicity. PMID:25128239

  20. Removal of Cd(II) and Pb(II) from wastewater by using triethylenetetramine functionalized grafted cellulose acetate-manganese dioxide composite.

    PubMed

    Yakout, Amr A; El-Sokkary, Ramadan H; Shreadah, Mohamed A; Abdel Hamid, Omnia G

    2016-09-05

    In this manuscript, we have studied the removal of Cd(II) and Pb(II) ions from aqueous solution by using triethylenetetramine functionalized cellulose acetate grafted with the copolymer-manganese dioxide composite. The novel sorbent cellulose was extracted from the mangrove trees (Avicennia marina) and it was then acetylated and grafted with acrylamide. The sorbent composite was designed to interact simultaneously with higher metal loading by complexation-adsorption process. FT-IR, SEM, EDAX and TGA techniques were employed to characterize the cellulose modified composite. Sorption equilibria were established after 30min and their data were described by Langmuir and Freundlich models. The functionalized hybrid cellulose composite showed maximum adsorption capacity 82.06 and 196.84mgg(-1) for Cd(II) and Pb(II), respectively. The studied metal ions were successfully recovered from real wastewater samples of different matrices.

  1. From the Cover: Manganese and Rotenone-Induced Oxidative Stress Signatures Differ in iPSC-Derived Human Dopamine Neurons.

    PubMed

    Neely, M Diana; Davison, Carrie Ann; Aschner, Michael; Bowman, Aaron B

    2017-10-01

    Parkinson's disease (PD) is the result of complex interactions between genetic and environmental factors. Two chemically distinct environmental stressors relevant to PD are the metal manganese and the pesticide rotenone. Both are thought to exert neurotoxicity at least in part via oxidative stress resulting from impaired mitochondrial activity. Identifying shared mechanism of action may reveal clues towards an understanding of the mechanisms underlying PD pathogenesis. Here we compare the effects of manganese and rotenone in human-induced pluripotent stem cells-derived postmitotic mesencephalic dopamine neurons by assessing several different oxidative stress endpoints. Manganese, but not rotenone caused a concentration and time-dependent increase in intracellular reactive oxygen/nitrogen species measured by quantifying the fluorescence of oxidized chloromethyl 2',7'-dichlorodihydrofluorescein diacetate (DCF) assay. In contrast, rotenone but not manganese caused an increase in cellular isoprostane levels, an indicator of lipid peroxidation. Manganese and rotenone both caused an initial decrease in cellular reduced glutathione; however, glutathione levels remained low in neurons treated with rotenone for 24 h but recovered in manganese-exposed cells. Neurite length, a sensitive indicator of overall neuronal health was adversely affected by rotenone, but not manganese. Thus, our observations suggest that the cellular oxidative stress evoked by these 2 agents is distinct yielding unique oxidative stress signatures across outcome measures. The protective effect of rasagiline, a compound used in the clinic for PD, had negligible impact on any of oxidative stress outcome measures except a subtle significant decrease in manganese-dependent production of reactive oxygen/nitrogen species detected by the DCF assay. © The Author 2017. Published by Oxford University Press on behalf of the Society of Toxicology. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  2. FOXO3 promoted mitophagy via nuclear retention induced by manganese chloride in SH-SY5Y cells.

    PubMed

    Song, Dongmei; Ma, Junxiang; Chen, Li; Guo, Caixia; Zhang, Yuanyuan; Chen, Tian; Zhang, Shixuan; Zhu, Zhonghui; Tian, Lin; Niu, Piye

    2017-09-20

    To evaluate the role of FOXO3 during the process of mitophagy induced by manganese chloride (MnCl2), mitochondrial dysfunction and mitophagy were detected before and after FOXO3 was knocked down in SH-SY5Y cells. Transmission electron microscopy (TEM), flow cytometry, confocal microscopy and a western blot were used to detect mitochondrial ultrastructure and autophagy, Ca(2+) levels, mitochondrial reactive oxygen species (ROS) and the mitochondrial membrane potential (MMP), autophagosomes and mitophagy marker proteins (p62, LC3-II/LC3-I, Beclin-1, PINK1 and P-parkin), respectively. After SH-SY5Y cells were exposed to MnCl2, the levels of cytoplasmic Ca(2+) and mitochondrial ROS increased but the mitochondrial MMP decreased significantly compared to the control in a dose- and time-dependent manner (p < 0.05), which indicated that MnCl2 can lead to mitochondrial dysfunction. Under TEM, mitophagy and autolysosomes were observed. The WB results also showed that mitophagy marker proteins including LC3-II/LC3-I, Beclin-1, PINK1 and P-parkin except for p62 increased in a dose- and time-dependent manner, accompanied by FOXO3 nuclear retention, which indicated that MnCl2 can lead to mitophagy and FOXO3 nuclear translocation may be involved in this process. After FOXO3 was knocked down, the inverse results of mitophagy and the levels of mitochondrial ROS decreasing were observed, which showed that FOXO3 silencing could inhibit mitophagy and mitochondrial dysfunction induced by MnCl2. Our results indicated that Mn could induce mitophagy by enhancing FOXO3 nuclear retention, which might promote mitophagy induced by MnCl2.

  3. Selective Separation and Extraction of Vanadium (V) Over Manganese (II) from Co-Leaching Solution of Roasted Stone Coal and Pyrolusite Using Solvent Extraction

    NASA Astrophysics Data System (ADS)

    Cai, Z. L.; Feng, Y. L.; Zhou, Y. Z.; Li, H. R.; Wang, W. D.

    2013-11-01

    Based on the novel technology for selective separation and extraction of vanadium (V) over manganese (II) from co-leaching solution of roasted stone coal and pyrolusite using solvent extraction, the extraction effect of vanadium (V) and manganese (II) has been studied and many technical conditions have also been optimized. Meanwhile, countercurrent simulation experiments were conducted to verify the results of the experiments. The results indicated that with three countercurrent extraction stages, 99.21% vanadium (V) was extracted using 5% (v/v) N235 and 5% (v/v) secondary octyl alcohol at initial aqueous pH of 3.0 and O/A phase ratio of 1.0. Vanadium (V) could be completely stripped after three-stage countercurrent experiments with 20 wt.% NH4Cl at O/A phase ratio of 1.0. The process flow sheet for the recovery of vanadium (V), as well as manganese (II), was proposed.

  4. Fluorophotometric determination of histone with 3,4,5,6-tetrafluoro-2-carboxyphenylfluorone-manganese(II) complex and its characterization.

    PubMed

    Miyachi, Kanako; Hoshino, Mitsuru; Kadobayashi, Hiroko; Moriyama, Kenzo; Asano, Mamiko; Yamaguchi, Takako; Fujita, Yoshikazu

    2013-01-01

    A simple fluorophotometric method for the determination of histone has been developed. This method involves a fluorescence quenching reaction that results in the formation of a complex of manganese(II), 3,4,5,6-tetrafluoro-2-carboxyphenylfluorone (TFCPF), and histone in a non-ionic surfactant micellar medium. The calibration curve was found to be linear in the range of 0.5 to 2.0 µg/mL. The binding parameters (n, number of binding sites; K, binding constant) and thermodynamic parameters (ΔG(0), change in Gibbs free energy; ΔH(0), change in enthalpy; ΔS(0), change in entropy) were investigated spectrophotometrically for the elucidation of the reaction mechanism. The resulting binding parameters (n=4.08 and K=3.16×10(4) m(-1) at 25°C) and thermodynamic parameters (ΔG=-25.83 kJ/mol, ΔH=-9.83 kJ/mol, and ΔS=53.68 J/(mol K)) suggest that the colored complex in this reaction system is an ion-association complex between manganese(II)-TFCPF and histone.

  5. Binding Selectivity of Methanobactin from Methylosinus trichosporium OB3b for Copper(I), Silver(I), Zinc(II), Nickel(II), Cobalt(II), Manganese(II), Lead(II), and Iron(II)

    NASA Astrophysics Data System (ADS)

    McCabe, Jacob W.; Vangala, Rajpal; Angel, Laurence A.

    2017-08-01

    Methanobactin (Mb) from Methylosinus trichosporium OB3b is a member of a class of metal binding peptides identified in methanotrophic bacteria. Mb will selectively bind and reduce Cu(II) to Cu(I), and is thought to mediate the acquisition of the copper cofactor for the enzyme methane monooxygenase. These copper chelating properties of Mb make it potentially useful as a chelating agent for treatment of diseases where copper plays a role including Wilson's disease, cancers, and neurodegenerative diseases. Utilizing traveling wave ion mobility-mass spectrometry (TWIMS), the competition for the Mb copper binding site from Ag(I), Pb(II), Co(II), Fe(II), Mn(II), Ni(II), and Zn(II) has been determined by a series of metal ion titrations, pH titrations, and metal ion displacement titrations. The TWIMS analyses allowed for the explicit identification and quantification of all the individual Mb species present during the titrations and measured their collision cross-sections and collision-induced dissociation patterns. The results showed Ag(I) and Ni(II) could irreversibly bind to Mb and not be effectively displaced by Cu(I), whereas Ag(I) could also partially displace Cu(I) from the Mb complex. At pH ≈ 6.5, the Mb binding selectivity follows the order Ag(I)≈Cu(I)>Ni(II)≈Zn(II)>Co(II)>>Mn(II)≈Pb(II)>Fe(II), and at pH 7.5 to 10.4 the order is Ag(I)>Cu(I)>Ni(II)>Co(II)>Zn(II)>Mn(II)≈Pb(II)>Fe(II). Breakdown curves of the disulfide reduced Cu(I) and Ag(I) complexes showed a correlation existed between their relative stability and their compact folded structure indicated by their CCS. Fluorescence spectroscopy, which allowed the determination of the binding constant, compared well with the TWIMS analyses, with the exception of the Ni(II) complex. [Figure not available: see fulltext.

  6. A novel cellulose-manganese oxide hybrid material by in situ soft chemical synthesis and its application for the removal of Pb(II) from water.

    PubMed

    Maliyekkal, Shihabudheen M; Lisha, Kinattukara P; Pradeep, T

    2010-09-15

    We report an in situ soft chemical synthesis of a novel hybrid material, cellulose-nanoscale-manganese oxide composite (C-NMOC), and its application for Pb(II) removal from aqueous solutions. For comparison, detailed Pb(II) adsorption studies were also performed with nanoscale-manganese oxide powder (NMO), prepared through a similar route. Various spectroscopic and microscopic techniques were used to characterize the as-synthesized materials. X-ray photoelectron spectroscopic (XPS) measurements confirmed the existence of Mn(IV) phase in NMO whereas C-NMOC showed largely the Mn(III) phase. The existence and uniform distribution of manganese oxide in cellulose fiber materials was confirmed by SEM and EDAX analyses. The adsorption studies reveal that the Pb(II) uptake onto C-NMOC is a fast process and >90% of the uptake occurred within the first 10 min contact time. The Sips isotherm predicted the equilibrium data well and the maximum Pb(II) uptake capacity of C-NMOC (4.64% Mn loading) was estimated to be 80.1 mg g(-1). The Pb(II) adsorption capacity of C-NMOC (per gram of Mn present) was several times higher than commercial manganese oxide (beta-MnO2) and at least twice larger than NMO. The experimental evidence reveals that physisorption plays a dominant role in Pb(II) adsorption by both NMO and C-NMOC.

  7. Manganese ferrite-based nanoparticles induce ex vivo, but not in vivo, cardiovascular effects

    PubMed Central

    Nunes, Allancer DC; Ramalho, Laylla S; Souza, Álvaro PS; Mendes, Elizabeth P; Colugnati, Diego B; Zufelato, Nícholas; Sousa, Marcelo H; Bakuzis, Andris F; Castro, Carlos H

    2014-01-01

    Magnetic nanoparticles (MNPs) have been used for various biomedical applications. Importantly, manganese ferrite-based nanoparticles have useful magnetic resonance imaging characteristics and potential for hyperthermia treatment, but their effects in the cardiovascular system are poorly reported. Thus, the objectives of this study were to determine the cardiovascular effects of three different types of manganese ferrite-based magnetic nanoparticles: citrate-coated (CiMNPs); tripolyphosphate-coated (PhMNPs); and bare magnetic nanoparticles (BaMNPs). The samples were characterized by vibrating sample magnetometer, X-ray diffraction, dynamic light scattering, and transmission electron microscopy. The direct effects of the MNPs on cardiac contractility were evaluated in isolated perfused rat hearts. The CiMNPs, but not PhMNPs and BaMNPs, induced a transient decrease in the left ventricular end-systolic pressure. The PhMNPs and BaMNPs, but not CiMNPs, induced an increase in left ventricular end-diastolic pressure, which resulted in a decrease in a left ventricular end developed pressure. Indeed, PhMNPs and BaMNPs also caused a decrease in the maximal rate of left ventricular pressure rise (+dP/dt) and maximal rate of left ventricular pressure decline (−dP/dt). The three MNPs studied induced an increase in the perfusion pressure of isolated hearts. BaMNPs, but not PhMNPs or CiMNPs, induced a slight vasorelaxant effect in the isolated aortic rings. None of the MNPs were able to change heart rate or arterial blood pressure in conscious rats. In summary, although the MNPs were able to induce effects ex vivo, no significant changes were observed in vivo. Thus, given the proper dosages, these MNPs should be considered for possible therapeutic applications. PMID:25031535

  8. 3D hierarchical flower-like nickel ferrite/manganese dioxide toward lead (II) removal from aqueous water.

    PubMed

    Xiang, Bo; Ling, Dong; Lou, Han; Gu, Hongbo

    2017-03-05

    A functionalized magnetic nickel ferrite/manganese dioxide (NiFe2O4/MnO2) with 3D hierarchical flower-like and core-shell structure was synthesized by a facile hydrothermal approach and applied for the removal of Pb(II) ions from aqueous solutions. Batch adsorption experiments were conducted to study the effect of solution pH, initial Pb(II) concentration, and dose of absorbents on the Pb(II) removal by NiFe2O4/MnO2. The NiFe2O4/MnO2 nanocomposites showed the fast Pb(II) adsorption performance with the maximum adsorption capacity of 85.78mgg(-1). The adsorption kinetics of Pb(II) onto NiFe2O4/MnO2 obeyed a pseudo-second-order model. The isothermal experimental results indicated that the Langmuir model was fitted better than the Freundlich model, illustrating a monolayer adsorption process for Pb(II) onto NiFe2O4/MnO2. Meanwhile, the NiFe2O4/MnO2 was easily separated from the solution by an external magnet within a short period of time and still exhibited almost 80% removal capacity after six regenerations. The NiFe2O4/MnO2 is expected to be a new promising adsorbent for heavy metal removal.

  9. Preparation of polyacrylnitrile (PAN)/ Manganese oxide based activated carbon nanofibers (ACNFs) for adsorption of Cadmium (II) from aqueous solution

    NASA Astrophysics Data System (ADS)

    Abdullah, N.; Yusof, N.; Jaafar, J.; Ismail, AF; Che Othman, F. E.; Hasbullah, H.; Salleh, W. N. W.; Misdan, N.

    2016-06-01

    In this work, activated carbon nanofibers (ACNFs) from precursor polyacrylnitrile (PAN) and manganese oxide (MnO2) were prepared via electrospinning process. The electrospun PAN/MnO2-based ACNFs were characterised in term of its morphological structure and specific surface area using SEM and BET analysis respectively. The comparative adsorption study of cadmium (II) ions from aqueous solution between the neat ACNFs, composite ACNFs and commercial granular activated carbon was also conducted. SEM analysis illustrated that composite ACNFs have more compact fibers with presence of MnO2 beads with smaller fiber diameter of 437.2 nm as compared to the neat ACNFs which is 575.5 nm. BET analysis elucidated specific surface area of ACNFs/MnO2 to be 67 m2/g. Under adsorption study, it was found out that Cd (II) removal by ACNFs/MnO2 was the highest (97%) followed by neat ACNFs (96%) and GAC (74%).

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

    PubMed Central

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

    2015-01-01

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

  11. Heavy metal pollution among autoworkers. II. Cadmium, chromium, copper, manganese, and nickel.

    PubMed Central

    Clausen, J; Rastogi, S C

    1977-01-01

    Garages and auto-repair workshops may be polluted with other heavy metals besides lead. Blood of autoworkers with high lead content was analysed for cadmium, chromium, copper manganese, nickel, ALAD activity and carboxyhaemoglobin level. Cadmium and copper levels in blood of autoworkers were comparable with those of the control subjects while chroimium and nickel levels were significantly higher (P less than 0-01 for both metals), and scattered raised values of manganese were found. There was no significant mutual correlation between levels of various heavy metals determined in whole blood. High copper levels were slightly related to decreasing ALAD activity (P less than 0-1). Nineteen per cent of autoworkers were found to have an abnormally blood level of carboxyhaemoglobin. The amount of particulate heavy metal in autoworkshop air was not related to biochemical abnormalities found in the autoworkers. Various sources of pollution of these heavy metals in autoworkshops are discussed. PMID:71915

  12. Extremely low-frequency magnetic field induces manganese accumulation in brain, kidney and liver of rats.

    PubMed

    Çelik, Mustafa Salih; Güven, Kemal; Akpolat, Veysi; Akdağ, Mehmet Zulkuf; Nazıroğlu, Mustafa; Gül-Güven, Reyhan; Çelik, M Yusuf; Erdoğan, Sait

    2015-06-01

    The aim of the present study was to determine the effects of extremely low-frequency magnetic field (ELF-MF) on accumulation of manganese (Mn) in the kidney, liver and brain of rats. A total of 40 rats were randomly divided into eight groups. Four control groups received 0, 3.75, 15 and 60 mg Mn per kg body weight orally every 2 days for 45 days, respectively. The remaining four groups received same concentrations of Mn and were also exposed to ELF-MF (1.5 mT; 50 Hz) for 4 h for 5 days a week during 45 days. Following the last exposure, kidney, liver and brain were taken from all rats and they were analyzed for Mn accumulation levels using an inductively coupled plasma-optical emission spectrometer. In result of the current study, we observed that Mn levels in brain, kidney and liver were higher in Mn groups than in control groups. Mn levels in brain, kidney and liver were also higher in Mn plus ELF-MF groups than in Mn groups. In conclusion, result of the current study showed that the ELF-MF induced manganese accumulation in kidney, liver and brain of rats.

  13. Degradation of the solid electrolyte interphase induced by the deposition of manganese ions

    NASA Astrophysics Data System (ADS)

    Shin, Hosop; Park, Jonghyun; Sastry, Ann Marie; Lu, Wei

    2015-06-01

    The deposition of manganese ions dissolved from the cathode onto the interface between the solid electrolyte interphase (SEI) and graphite causes severe capacity fading in manganese oxide-based cells. The evolution of the SEI layer containing these Mn compounds and the corresponding instability of the layer are thoroughly investigated by artificially introducing soluble Mn ions into a 1 mol L-1 LiPF6 electrolyte solution. Deposition of dissolved Mn ions induces an oxygen-rich SEI layer that results from increased electrolyte decomposition, accelerating SEI growth. The spatial distribution of Mn shows that dissolved Mn ions diffuse through the porous layer and are deposited mostly at the inorganic layer/graphite interface. The Mn compound deposited on the anode, identified as MnF2, originates from a metathesis reaction between LiF and dissolved Mn ion. It is confirmed that ion-exchange reaction occurs in the inorganic layer, converting SEI species to Mn compounds. Some of the Mn is observed inside the graphite; this may cause surface structural disordering in the graphite, limiting lithium-ion intercalation. The continuous reaction that occurs at the inorganic layer/graphite interfacial regions and the modification of the original SEI layer in the presence of Mn ions are critically related to capacity fade and impedance rise currently plaguing Li-ion cells.

  14. [Determination of trace manganese by non-organic solvents extraction catalytic spectrophotometry in Mn(II)-H2O2-EBT-PEG-2000 system].

    PubMed

    Sun, Deng-ming; Fang, Hua-cai

    2005-08-01

    A new non-organic solvents extraction catalytic spectrophotometric method for the determination of trace amounts of manganese was studied. The method is based onthe manganese (II) catalyzing hydrogen peroxide to oxidate o f eriochrome black T in hydroxide-ammonium chloride buffer medium. The reaction time and the degree of indicating reaction are controlled by non-organic solvents extraction equilibrium using polyethylene glycol-2000. The absorbance of polyethylene glycol-2000 phase is measured at 539 nm in weak acidic medium. The calibration graph is linear for 0.0080-0.55 microg x mL(-1) Mn (II), and the detection limit is 3.0 x 10(-9) g x L(-1). The method can be applied to the determination of trace manganese in tea and aluminum alloy with satisfactory results.

  15. Acclimation of a marine microbial consortium for efficient Mn(II) oxidation and manganese containing particle production.

    PubMed

    Zhou, Hao; Pan, Haixia; Xu, Jianqiang; Xu, Weiping; Liu, Lifen

    2016-03-05

    Sediment contamination with metals is a widespread concern in the marine environment. Manganese oxidizing bacteria (MOB) are extensively distributed in various environments, but a marine microbial community containing MOB is rarely reported. In this study, a consortium of marine metal-contaminated sediments was acclimated using Mn(II). The shift in community structure was determined through high-throughput sequencing. In addition, the consortium resisted several harsh conditions, such as toxic metals (1mM Cu(II) and Fe(III)), and exhibited high Mn(II) oxidation capacities even the Mn(II) concentration was up to 5mM. Meanwhile, biogenic Mn containing particles were characterized by scanning electron microscope (SEM), X-ray powder diffraction (XRD), and N2 adsorption/desorption. Dye removal performance of the Mn containing particles was assayed using methylene blue, and 20.8 mg g(-1) adsorption capacity was obtained. Overall, this study revealed several new genera associated with Mn(II) oxidation and rare biogenic Na3MnPO4CO3. Results suggested the complexity of natural microbe-mediated Mn transformation.

  16. Excess Manganese-Induced Apoptosis in Chicken Cerebrums and Embryonic Neurocytes.

    PubMed

    Zhang, Kun; Zhu, Yihao; Wang, Xiaoyu; Zhao, Xin; Li, Shu; Teng, Xiaohua

    2017-03-30

    There were many studies about the effect of excess manganese (Mn) on nervous system apoptosis; however, Mn-induced apoptosis in chicken cerebrums and embryonic neurocytes was unclear. The purpose of this study was to investigate the effect of excess Mn on chicken cerebrum and embryonic neurocyte apoptosis. Seven-day-old Hyline male chickens were fed either a commercial diet or three levels of manganese chloride (MnCl2)-added commercial diets containing 600-, 900-, and 1800-mg/kg-Mn diet, respectively. On the 30th, 60th, and 90th days, cerebrums were collected. Fertilized Hyline chicken eggs were hatched for 6-8 days and were selected. Embryonic neurocytes with 0, 0.5, 1, 1.5, 2, 2.5, and 3 mM Mn were collected and were cultured for 12, 24, 36, and 48 h, respectively. The following research contents were performed: superoxide dismutase (SOD) and total antioxidant capacity (T-AOC) activities; tumor protein p53 (p53), B cell lymphoma-2 (Bcl-2), B cell lymphoma extra large (Bcl-x), Bcl-2-associated X protein (Bax), Bcl-2 homologous antagonist/killer (Bak), fas, and caspase-3 messenger RNA (mRNA) expression; and morphologic observation. The results indicated that excess Mn inhibited SOD and T-AOC activities; induced p53, Bax, Bak, fas, and caspase-3 mRNA expression; and inhibited Bcl-2 and Bcl-x mRNA expression in chicken cerebrums and embryonic neurocytes. There were dose-dependent manners on all the above factors at all the time points and time-dependent manners on SOD activity of 1800-mg/kg-Mn group, T-AOC activity, and apoptosis-related gene mRNA expression in all the treatment groups in chicken cerebrums. Excess Mn induced chicken cerebrum and embryonic neurocyte apoptosis.

  17. Proton Matrix ENDOR Studies on Ca2+-depleted and Sr2+-substituted Manganese Cluster in Photosystem II*

    PubMed Central

    Nagashima, Hiroki; Nakajima, Yoshiki; Shen, Jian-Ren; Mino, Hiroyuki

    2015-01-01

    Proton matrix ENDOR spectra were measured for Ca2+-depleted and Sr2+-substituted photosystem II (PSII) membrane samples from spinach and core complexes from Thermosynechococcus vulcanus in the S2 state. The ENDOR spectra obtained were similar for untreated PSII from T. vulcanus and spinach, as well as for Ca2+-containing and Sr2+-substituted PSII, indicating that the proton arrangements around the manganese cluster in cyanobacterial and higher plant PSII and Ca2+-containing and Sr2+-substituted PSII are similar in the S2 state, in agreement with the similarity of the crystal structure of both Ca2+-containing and Sr2+-substituted PSII in the S1 state. Nevertheless, slightly different hyperfine separations were found between Ca2+-containing and Sr2+-substituted PSII because of modifications of the water protons ligating to the Sr2+ ion. Importantly, Ca2+ depletion caused the loss of ENDOR signals with a 1.36-MHz separation because of the loss of the water proton W4 connecting Ca2+ and YZ directly. With respect to the crystal structure and the functions of Ca2+ in oxygen evolution, it was concluded that the roles of Ca2+ and Sr2+ involve the maintenance of the hydrogen bond network near the Ca2+ site and electron transfer pathway to the manganese cluster. PMID:26438823

  18. Proton Matrix ENDOR Studies on Ca2+-depleted and Sr2+-substituted Manganese Cluster in Photosystem II.

    PubMed

    Nagashima, Hiroki; Nakajima, Yoshiki; Shen, Jian-Ren; Mino, Hiroyuki

    2015-11-20

    Proton matrix ENDOR spectra were measured for Ca(2+)-depleted and Sr(2+)-substituted photosystem II (PSII) membrane samples from spinach and core complexes from Thermosynechococcus vulcanus in the S2 state. The ENDOR spectra obtained were similar for untreated PSII from T. vulcanus and spinach, as well as for Ca(2+)-containing and Sr(2+)-substituted PSII, indicating that the proton arrangements around the manganese cluster in cyanobacterial and higher plant PSII and Ca(2+)-containing and Sr(2+)-substituted PSII are similar in the S2 state, in agreement with the similarity of the crystal structure of both Ca(2+)-containing and Sr(2+)-substituted PSII in the S1 state. Nevertheless, slightly different hyperfine separations were found between Ca(2+)-containing and Sr(2+)-substituted PSII because of modifications of the water protons ligating to the Sr(2+) ion. Importantly, Ca(2+) depletion caused the loss of ENDOR signals with a 1.36-MHz separation because of the loss of the water proton W4 connecting Ca(2+) and YZ directly. With respect to the crystal structure and the functions of Ca(2+) in oxygen evolution, it was concluded that the roles of Ca(2+) and Sr(2+) involve the maintenance of the hydrogen bond network near the Ca(2+) site and electron transfer pathway to the manganese cluster.

  19. Melatonin Attenuates Manganese and Lipopolysaccharide-Induced Inflammatory Activation of BV2 Microglia.

    PubMed

    Park, Euteum; Chun, Hong Sung

    2017-02-01

    Melatonin, a naturally occurring neurohormone in the pineal gland, has been shown to exert antioxidant and anti-inflammatory effects. This study examined the effects of melatonin on manganese (Mn) and/or lipopolysaccharide (LPS)-induced microglial activation. Melatonin (10 μM) inhibited Mn (100 μM) and/or LPS (0.5 μg/ml)-induced phagocytotic activity of activated BV2 microglia. It also inhibited the lipid peroxidation and intracellular reduced glutathione (GSH) depletion induced by Mn and/or LPS. Melatonin effectively suppressed the upregulation of interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) at both mRNA and protein levels in Mn and/or LPS-stimulated BV2 microglia. In addition, melatonin pretreatment attenuated Mn and/or LPS-induced degradation of IκB-α, nuclear translocation of nuclear factor-κB (NF-κB) and its activation, and the expressions of inducible nitric oxide synthase (iNOS) and nitric oxide (NO) in BV2 microglial cells. These results suggest that melatonin can effectively modulate phagocytosis and expression of proinflammatory mediators, and can prevent neuroinflammatory disorders accompanied by microglial activation.

  20. Decoration of the layered manganese oxide birnessite with Mn(II/III) gives a new water oxidation catalyst with fifty-fold turnover number enhancement.

    PubMed

    McKendry, Ian G; Kondaveeti, Sandeep K; Shumlas, Samantha L; Strongin, Daniel R; Zdilla, Michael J

    2015-08-07

    The role of the manganese average oxidation state (AOS) in water oxidation catalysis by birnessite was investigated. Low AOS samples were most active, generating O2 immediately. Samples with a relatively high AOS showed an initial induction period and decreased turnover. Mn(ii- and iii)-enriched samples gave a 10-50 fold enhancement in turnover number.

  1. Manganese leads to an increase in markers of oxidative stress as well as to a shift in the ratio of Fe(II)/(III) in rat brain tissue.

    PubMed

    Fernsebner, Katharina; Zorn, Julia; Kanawati, Basem; Walker, Alesia; Michalke, Bernhard

    2014-04-01

    Occupationally or environmentally caused chronic exposure to Manganese (Mn) can lead to a degeneration of dopaminergic neurons inducing a Parkinson-like complaint called manganism. Deciphering the ongoing neurodegenerative mechanisms in the affected brain is still a major task for understanding the complex modes of action. Therefore, we applied a non-toxic, oral feeding in rats simulating a chronic exposure to Mn. Analysis of brain extracts by electrospray ionization Fourier transform resonance mass spectrometry (ESI-FT-ICR-MS) revealed an increase in markers of oxidative stress like glutathione disulfide (GSSG), prostaglandins, and 15(S)-HETE, a marker of lipid peroxidation. Furthermore, acetylcholinesterase (AchE) activity and glutamate concentrations were elevated in brain samples of Mn-supplemented rats, suggesting oxidative stress in the brain tissue. Application of ion chromatography coupled to inductively coupled plasma-optical emission spectrometry (IC-ICP-OES) further showed a shift of Fe(III) towards Fe(II) in the brain samples enabling for example the action of the Fenton reaction. This is the first time that changes in the Fe-species distribution could be related to Mn-induced neuroinflammation and is therefore enlarging the knowledge of this complex neurodegenerative condition. The combination of our findings provides substantial evidence that Mn-induced neuroinflammation leads to oxidative stress triggered by multifactorial pathophysiological processes.

  2. Purity control of uranium by neutron activation assay--II. Determination of manganese, nickel and copper.

    PubMed

    Abdel-Rassoul, A A; Wahba, S S

    1967-09-01

    Activation analysis is applied for the simultaneous determination of manganese, nickel and copper in different uranium samples, including metallic uranium, uranium concentrates, oxide, acetate, nitrate and sodium uranate. The analytical scheme developed is based on separation of the uranium by paper chromatography and subsequent determination of these elements in the pile-irradiated residues by simple radiochemical operations. The reliability of the scheme proposed is tested, and the limits of sensitivity of the methods worked out are ascertained. Accordingly, microgram concentrations of the elements studied could be assayed in limited quantities of the samples analysed with a precision of +/- 15%. Reagent-blank determinations are also considered.

  3. Manganese oxidation induced by water table fluctuations in a sand column.

    PubMed

    Farnsworth, Claire E; Voegelin, Andreas; Hering, Janet G

    2012-01-03

    On-off cycles of production wells, especially in bank filtration settings, cause oscillations in the local water table, which can deliver significant amounts of dissolved oxygen (DO) to the shallow groundwater. The potential for DO introduced in this manner to oxidize manganese(II) (Mn(II)), mediated by the obligate aerobe Pseudomonas putida GB-1, was tested in a column of quartz sand fed with anoxic influent solution and subject to 1.3 m water table changes every 30-50 h. After a period of filter ripening, 100 μM Mn was rapidly removed during periods of low water table and high dissolved oxygen concentrations. The accumulation of Mn in the column was confirmed by XRF analysis of the sand at the conclusion of the study, and both measured net oxidation rates and XAS analysis suggest microbial oxidation as the dominant process. The addition of Zn, which inhibited GB-1 Mn oxidation but not its growth, interrupted the Mn removal process, but Mn oxidation recovered within one water table fluctuation. Thus transient DO conditions could support microbially mediated Mn oxidation, and this process could be more relevant in shallow groundwater than previously thought.

  4. N-acetylcysteineamide protects against manganese-induced toxicity in SHSY5Y cell line.

    PubMed

    Maddirala, Yasaswi; Tobwala, Shakila; Ercal, Nuran

    2015-05-22

    Manganese (Mn) is an essential trace element required for normal cellular functioning. However, overexposure of Mn can be neurotoxic resulting in the development of manganism, a syndrome that resembles Parkinson׳s disease. Although the pathogenetic basis of this disorder is unclear, several studies indicate that it is mainly associated with oxidative stress and mitochondrial energy failure. Therefore, this study is focused on (1) investigating the oxidative effects of Mn on neuroblastoma cells (SHSY5Y) and (2) elucidating whether a novel thiol antioxidant, N-acetylcysteineamide (NACA), provides any protection against Mn-induced neurotoxicity. Reactive oxygen species (ROS) were highly elevated after the exposure, indicating that mechanisms that induce oxidative stress were involved. Measures of oxidative stress parameters, such as glutathione (GSH), malondialdehyde (MDA), and activities of glutathione reductase (GR) and glutathione peroxidase (GPx) were altered in the Mn-treated groups. Loss of mitochondrial membrane potential, as assessed by flow cytometry and decreased levels of ATP, indicated that cytotoxicity was mediated through mitochondrial dysfunction. However, pretreatment with NACA protected against Mn-induced toxicity by inhibiting lipid peroxidation, scavenging ROS, and preserving intracellular GSH and mitochondrial membrane potential. NACA can potentially be developed into a promising therapeutic option for Mn-induced neurotoxicity. This article is part of a Special Issue entitled SI: Metals in neurodegeneration. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Mechanistic insight into chromium(VI) reduction by oxalic acid in the presence of manganese(II).

    PubMed

    Wrobel, Katarzyna; Corrales Escobosa, Alma Rosa; Gonzalez Ibarra, Alan Alexander; Mendez Garcia, Manuel; Yanez Barrientos, Eunice; Wrobel, Kazimierz

    2015-12-30

    Over the past few decades, reduction of hexavalent chromium (Cr(VI)) has been studied in many physicochemical contexts. In this research, we reveal the mechanism underlying the favorable effect of Mn(II) observed during Cr(VI) reduction by oxalic acid using liquid chromatography with spectrophotometric diode array detector (HPLC-DAD), nitrogen microwave plasma atomic emission spectrometry (HPLC-MP-AES), and high resolution mass spectrometry (ESI-QTOFMS). Both reaction mixtures contained potassium dichromate (0.67 mM Cr(VI)) and oxalic acid (13.3mM), pH 3, one reaction mixture contained manganese sulfate (0.33 mM Mn(II)). In the absence of Mn(II) only trace amounts of reaction intermediates were generated, most likely in the following pathways: (1) Cr(VI)→ Cr(IV) and (2) Cr(VI)+Cr(IV)→ 2Cr(V). In the presence of Mn(II), the active reducing species appeared to be Mn(II) bis-oxalato complex (J); the proposed reaction mechanism involves a one-electron transfer from J to any chromium compound containing CrO bond, which is reduced to CrOH, and the generation of Mn(III) bis-oxalato complex (K). Conversion of K to J was observed, confirming the catalytic role of Mn(II). Since no additional acidification was required, the results obtained in this study may be helpful in designing a new, environmentally friendly strategy for the remediation of environments contaminated with Cr(VI). Copyright © 2015 Elsevier B.V. All rights reserved.

  6. The Porphyromonas gingivalis HmuY haemophore binds gallium(iii), zinc(ii), cobalt(iii), manganese(iii), nickel(ii), and copper(ii) protoporphyrin IX but in a manner different to iron(iii) protoporphyrin IX.

    PubMed

    Wójtowicz, Halina; Bielecki, Marcin; Wojaczyński, Jacek; Olczak, Mariusz; Smalley, John W; Olczak, Teresa

    2013-04-01

    Porphyromonas gingivalis, a major etiological agent of chronic periodontitis, acquires haem from host haemoproteins through a haem transporter HmuR and a haemophore HmuY. The aim of this study was to analyse the binding specificity of HmuY towards non-iron metalloporphyrins which may be employed as antimicrobials to treat periodontitis. HmuY binds gallium(iii), zinc(ii), cobalt(iii), manganese(iii), nickel(ii), and copper(ii) protoporphyrin IX but in a manner different to iron(iii) protoporphyrin IX which uses His(134) and His(166) as axial ligands. The metal ions in Ga(iii)PPIX and Zn(ii)PPIX can accept only His(166) as an axial ligand, whereas nickel(ii) and copper(ii) interact exclusively with His(134). Two forms of pentacoordinate manganese(iii) are present in the Mn(iii)PPIX-HmuY complex since the metal accepts either His(134) or His(166) as a single axial ligand. The cobalt ion is hexacoordinate in the Co(iii)PPIX-HmuY complex and binds His(134) and His(166) as axial ligands; however, some differences in their environments exist. Despite different coordination modes of the central metal ion, gallium(iii), zinc(ii), cobalt(iii), and manganese(iii) protoporphyrin IX bound to the HmuY haemophore cannot be displaced by excess haem. All of the metalloporphyrins examined bind to a P. gingivalis wild-type strain with higher ability compared to a mutant strain lacking a functional hmuY gene, thus corroborating binding of non-iron metalloporphyrins to purified HmuY protein. Our results further clarify the basis of metalloporphyrin acquisition by P. gingivalis and add to understanding of the interactions with porphyrin derivatives which exhibit antimicrobial activity against P. gingivalis.

  7. Electrocatalytic oxidation of 2-mercaptoethanol using modified glassy carbon electrode by MWCNT in combination with unsymmetrical manganese (II) Schiff base complexes

    SciTech Connect

    Mohebbi, Sajjad Eslami, Saadat

    2015-06-15

    Highlights: • High electocatalytic efficiency and stability of modified hybrid electrode GC/MWCNTs/MnSaloph. • Direct reflection of catalytic activity of manganese complexes on electrocatalytic oxidation of 2-ME. • Decreasing overpotential and increasing catalytic peak current toward oxidation of 2-ME. • Deposition of range of novel substituted N{sub 2}O{sub 2} Saloph complexes of manganese(II) on GCE/MWCNT. • Enhancement of electrocatalytic oxidation activity upon electron donating substitutions on the Saloph. - Abstract: The performance of modified hybrid glassy carbon electrode with composite of carbon nanotubes and manganese complexes for the electrocatalytic oxidation of 2-mercaptoethanol is developed. GC electrode was modified using MWCNT and new N{sub 2}O{sub 2} unsymmetrical tetradentate Schiff base complexes of manganese namely Manganese Saloph complexes 1-5, with general formula Mn[(5-x-4-y-Sal)(5-x′-4-y′-Sal) Ph], where x, x′ = H, Br, NO{sub 2} and y, y′ = H, MeO. Direct immobilization of CNT on the surface of GCE is performed by abrasive immobilization, and then modified by manganese(II) complexes via direct deposition method. These novel modified electrodes clearly demonstrate the necessity of modifying bare carbon electrodes to endow them with the desired behavior and were identified by HRTEM. Also complexes were characterized by elemental analyses, MS, UV–vis and IR spectroscopy. Modified hybrid GC/MWCNT/MnSaloph electrode exhibits strong and stable electrocatalytic activity towards the electrooxidation of 2-mercaptoethanol molecules in comparison with bare glassy carbon electrode with advantages of very low over potential and high catalytic current. Such ability promotes the thiol’s electron transfer reaction. Also, electron withdrawing substituent on the Saloph was enhanced electrocatalytic oxidation activity.

  8. Normal Cellular Prion Protein Protects against Manganese-induced Oxidative Stress and Apoptotic Cell Death

    PubMed Central

    Choi, Christopher J.; Anantharam, Vellareddy; Saetveit, Nathan J.; Houk, Robert. S.; Kanthasamy, Arthi; Kanthasamy, Anumantha G.

    2012-01-01

    The normal prion protein is abundantly expressed in the CNS, but its biological function remains unclear. The prion protein has octapeptide repeat regions that bind to several divalent metals, suggesting that the prion proteins may alter the toxic effect of environmental neurotoxic metals. In the present study, we systematically examined whether prion protein modifies the neurotoxicity of manganese (Mn) by comparing the effect of Mn on mouse neural cells expressing prion protein (PrPC -cells) and prion-knockout (PrPKO -cells). Exposure to Mn (10 μM-1 mM) for 24 hr produced a dose-dependent cytotoxic response in both PrPC -cells and PrPKO -cells. Interestingly, PrPC -cells (EC50 117.6μM) were more resistant to Mn-induced cytotoxicity, as compared to PrPKO -cells (EC50 59.9μM), suggesting a protective role for PrPC against Mn neurotoxicity. Analysis of intracellular Mn levels showed less Mn accumulation in PrPC -cells as compared to PrPKO -cells. Furthermore, Mn-induced mitochondrial depolarization and ROS generation were significantly attenuated in PrPC -cells as compared to PrPKO -cells. Measurement of antioxidant status revealed similar basal levels of glutathione (GSH) in PrPC -cells and PrPKO -cells; however, Mn treatment caused greater depletion of GSH in PrPKO -cells. Mn-induced mitochondrial depolarization and ROS production were followed by time- and dose-dependent activation of the apoptotic cell death cascade involving caspase-9 and -3. Notably, DNA fragmentation induced by both Mn treatment and oxidative stress-inducer hydrogen peroxide (100μM) was significantly suppressed in PrPC -cells as compared to PrPKO -cells. Together, these results demonstrate that prion protein interferes with divalent metal Mn uptake and protects against Mn-induced oxidative stress and apoptotic cell death. PMID:17483122

  9. Interaction of manganese(II) complex with apotransferrin and the apotransferrin enhanced anticancer activities

    NASA Astrophysics Data System (ADS)

    Yao, Ling; Chen, Qiu-Yun; Xu, Xiao-Lei; Li, Zan; Wang, Xue-Ming

    2013-03-01

    Apotransferrin could bind a number of metal ions besides Fe, which makes it an attractive delivery vehicle for metal-based medicines. In order to evaluate whether anticancer Mn(II) complex of [(Adpa)Mn(Cl)(H2O)] Adpa = bis(2-pyridylmethyl)amino-2-propionic acid) (AdpaMn) could be transported by apotransferrin, we investigated its interaction with human apotransferrin by fluorescence and circular dichroism spectroscopy (CD). The association dynamics show that AdpaMn could bind to apotransferrin spontaneously in Hepes buffer. Synchronous fluorescence spectroscopy and CD spectroscopy show that the conjugation of AdpaMn and apotransferrin by hydrophobic interactions induces the change of the microenvironment and conformation of apotransferrin. The reversible binding and release of AdpaMn was studied with fluorescence titration method. The AdpaMn complex can be released from the AdpaMn-apotransferrin entity in weak acid environments. MTT assay in vitro confirms that apotransferrin can enhance the inhibition rate of AdpaMn on the proliferation of HepG-2 cells, so we deduce that AdpaMn could be transported by apotransferrin in vivo.

  10. Magnetic multi-wall carbon nanotube nanocomposite as an adsorbent for preconcentration and determination of lead (II) and manganese (II) in various matrices.

    PubMed

    Daneshvar Tarigh, Ghazale; Shemirani, Farzaneh

    2013-10-15

    Magnetic multi-wall carbon nanotube (MMWCNT) nanocomposite was synthesized and used as an adsorbent for preconcentration and determination of lead (II) and manganese (II). The properties of MMWCNT were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Energy dispersive X-ray spectrometry (EDS) and fourier transform infrared spectrophotometer (FT-IR). This adsorbent was found to be advantageous over conventional solid phase extraction (SPE) in terms of operational simplicity and low time-consuming. MMWCNT, carrying target metals, was easily separated from the aqueous solutions with the help of an external magnet; so, no filtration or centrifugation was necessary. After extraction and collection of MMWCNT, the adsorbed analytes were eluted and analyzed by flame atomic absorption spectrometry (FAAS). Experiments were carried out to investigate the influence of different sorption/desorption parameters. Under the optimized conditions, detection limits and enhancement factors of the proposed method for Pb and Mn were 1.0 and 0.6 µg L(-1), 390 and 697 respectively. The presented procedure was successfully applied for determination of Pb(II) and Mn (II) contents in lipstick, rice samples and accuracy was evaluated analyzing a certified reference material Seronorm(™) Urine LOT NO2525. Copyright © 2013 Elsevier B.V. All rights reserved.

  11. Structural analysis and physico-chemical characterization of mononuclear manganese(II) and polynuclear copper(II) complexes with pyridine-based alcohol

    NASA Astrophysics Data System (ADS)

    Zienkiewicz-Machnik, Małgorzata; Masternak, Joanna; Kazimierczuk, Katarzyna; Barszcz, Barbara

    2016-12-01

    Two novel manganese(II) and copper(II) complexes, mononuclear [Mn(H2O)2(2-(CH2)2OHpy)2](NO3)2 (1) and polynuclear [Cu(SO4)(2-(CH2)2OHpy)2]n (2), based on 2-(hydroxyethyl)pyridine (2-(CH2)2OHpy) were synthesised and fully characterised using X-ray structure analysis as well as spectroscopic, magnetic and thermal methods. Both central metal ions Mn(1) and Cu(1) are coordinated by two N,O-donor 2-(CH2)2OHpy ligands and possess an almost perfect octahedral geometry (a chromophore of {MN2O4} type). The coordination sphere of Mn(II) is completed by two molecules of water, whereas, in polynuclear complex 2, Cu(II) atoms are linked along the a crystallographic direction by bridging sulfate ligands in a μ2-κ2 binding mode to form chains. The intermolecular interactions in 1 and 2 have been interpreted in view of the 3D Hirshfeld surface analysis and associated 2D fingerprint plots. Furthermore, the complexes have been tested with ABTSrad + assay in order to assess their antioxidant activity. In addition, the IC50 values calculated for 1 and 2 revealed that the complexes show a higher antioxidant activity than corresponding ligand.

  12. "Manganese-induced neurotoxicity: a review of its behavioral consequences and neuroprotective strategies".

    PubMed

    Peres, Tanara V; Schettinger, Maria Rosa C; Chen, Pan; Carvalho, Fabiano; Avila, Daiana S; Bowman, Aaron B; Aschner, Michael

    2016-11-04

    Manganese (Mn) is an essential heavy metal. However, Mn's nutritional aspects are paralleled by its role as a neurotoxicant upon excessive exposure. In this review, we covered recent advances in identifying mechanisms of Mn uptake and its molecular actions in the brain as well as promising neuroprotective strategies. The authors focused on reporting findings regarding Mn transport mechanisms, Mn effects on cholinergic system, behavioral alterations induced by Mn exposure and studies of neuroprotective strategies against Mn intoxication. We report that exposure to Mn may arise from environmental sources, occupational settings, food, total parenteral nutrition (TPN), methcathinone drug abuse or even genetic factors, such as mutation in the transporter SLC30A10. Accumulation of Mn occurs mainly in the basal ganglia and leads to a syndrome called manganism, whose symptoms of cognitive dysfunction and motor impairment resemble Parkinson's disease (PD). Various neurotransmitter systems may be impaired due to Mn, especially dopaminergic, but also cholinergic and GABAergic. Several proteins have been identified to transport Mn, including divalent metal tranporter-1 (DMT-1), SLC30A10, transferrin and ferroportin and allow its accumulation in the central nervous system. Parallel to identification of Mn neurotoxic properties, neuroprotective strategies have been reported, and these include endogenous antioxidants (for instance, vitamin E), plant extracts (complex mixtures containing polyphenols and non-characterized components), iron chelating agents, precursors of glutathione (GSH), and synthetic compounds that can experimentally afford protection against Mn-induced neurotoxicity.

  13. Recombinant Mitochondrial Manganese Containing Superoxide Dismutase Protects Against Ochratoxin A-Induced Nephrotoxicity.

    PubMed

    Ciarcia, Roberto; Damiano, Sara; Squillacioti, Caterina; Mirabella, Nicola; Pagnini, Ugo; Florio, Alessia; Severino, Lorella; Capasso, Giovambattista; Borrelli, Antonella; Mancini, Aldo; Boffo, Silvia; Romano, Gaetano; Giordano, Antonio; Florio, Salvatore

    2016-06-01

    Ochratoxin A (OTA) is a natural mycotoxin, involved in the development of important human and animal diseases. In this work we have studied the role of oxidative stress in the development of OTA nephrotoxicity and the effect of a new recombinant mitochondrial manganese containing superoxide dismutase (rMnSOD) to prevent kidney damage induced by OTA. Blood pressure, glomerular filtration rate and renal histology were analyzed in control rats and in OTA treated rats. In addition, lipid peroxidation, catalase and superoxide dismutase productions were measured. Our data showed that animals treated with OTA presented hypertension and reduction of glomerular filtration rate (GFR). These effects are most probably related to an increase in the reactive oxygen species (ROS) productions. In fact, we have shown that treatment with rMnSOD restored the levels of blood pressure and GFR simultaneously. Moreover, we have noted that OTA induced alteration on glomerular and tubular degeneration and interstitial infiltrates and that use of rMnSOD combined with OTA prevent this renal histological damage confirming the potential therapeutic role in the treatment of rMnSOD OTA nephrotoxicity.

  14. Inducible nitric oxide synthase gene methylation and parkinsonism in manganese-exposed welders

    PubMed Central

    Nielsen, Susan Searles; Checkoway, Harvey; Criswell, Susan R.; Farin, Federico M.; Stapleton, Patricia L.; Sheppard, Lianne; Racette, Brad A.

    2015-01-01

    Introduction Neurologist-assessed parkinsonism signs are prevalent among workers exposed to manganese (Mn)-containing welding fume. Neuroinflammation may possibly play a role. Inducible nitric oxide synthase, coded by NOS2, is involved in inflammation, and particulate exposure increases the gene’s expression through methylation of CpG sites in the 5′ region. Methods We assessed DNA methylation at three CpG sites in the NOS2 exon 1 from blood from 201 welders. All were non-Hispanic Caucasian men 25–65 years old who were examined by a neurologist specializing in movement disorders. We categorized the workers according to their Unified Parkinson Disease Rating Scale motor subsection 3 (UPDRS3) scores as parkinsonism cases (UPDRS3 ≥ 15; n = 49), controls (UPDRS3 < 6; n = 103), or intermediate (UPDRS3 ≥6 to <15; n = 49). Results While accounting for age, examiner and experimental plate, parkinsonism cases had lower mean NOS2 methylation than controls (p-value for trend = 0.04), specifically at CpG site 8329 located in an exonic splicing enhancer of NOS2 (p-value for trend = 0.07). These associations were not observed for the intermediate UPDRS3 group (both p-value for trend ≥ 0.59). Conclusions Inflammation mediated by inducible nitric oxide synthase may possibly contribute to the association between welding fume and parkinsonism, but requires verification in a longitudinal study. PMID:25634431

  15. NTP Toxicology and Carcinogenesis Studies of Manganese (II) Sulfate Monohydrate (CAS No. 10034-96-5) in F344/N Rats and B6C3F1 Mice (Feed Studies).

    PubMed

    1993-12-01

    not mutagenic in Salmonella typhimurium strains TA97, TA98, TA100, TA1535, or TA1537, with or without exogenous metabolic activation (S9), and did not induce sex-linked recessive lethal mutations in germ cells of male Drosophila melanogaster. Tests for induction of sister chromatid exchanges and chromosomal aberrations in cultured Chinese hamster ovary cells treated without S9 were positive; with S9, only the sister chromatid exchange test with manganese (11) sulfate monohydrate was positive. CONCLUSIONS: Under the conditions of these 2-year feed studies, there was no evidence of carcinogenic activity of manganese (II) sulfate monohydrate in male or female F344/N rats receiving 1,500, 5,000, or 15,000 ppm. There was equivocal evidence of carcinogenic activity of manganese (II) sulfate monohydrate in male and female B6C3F1 mice, based on the marginally increased incidences of thyroid gland follicular cell adenoma and the significantly increased incidences of follicular cell hyperplasia. The ingestion of diets containing manganese (II) sulfate monohydrate was associated with an increased severity of nephropathy in male rats, focal squamous hyperplasia of the forestomach in male and female mice, and ulcers and inflammation of the forestomach in male mice. These studies were not designed to assess any neurotoxicity that might have been expected with chronic exposure to sufficiently high doses of manganese. Synonyms: Manganese sulfate; manganous sulfate; sulfuric acid. manganese2+ salt (1:1), monohydrate

  16. Estrogen and tamoxifen reverse manganese-induced glutamate transporter impairment in astrocytes.

    PubMed

    Lee, Eun-Sook Y; Sidoryk, Marta; Jiang, Haiyan; Yin, Zhaobao; Aschner, Michael

    2009-07-01

    Chronic exposure to manganese (Mn) can cause manganism, a neurodegenerative disorder similar to Parkinson's disease. The toxicity of Mn includes impairment of astrocytic glutamate transporters. 17beta-Estradiol (E2) has been shown to be neuroprotective in various neurodegenerative diseases including Parkinson's disease and Alzheimer's disease, and some selective estrogen receptor modulators, including tamoxifen (TX), also possess neuroprotective properties. We have tested our hypothesis that E2 and TX reverse Mn-induced glutamate transporter impairment in astrocytes. The results established that E2 and TX increased glutamate transporter function and reversed Mn-induced glutamate uptake inhibition, primarily via the up-regulation of glutamate/aspartate transporter (GLAST). E2 and TX also increased astrocytic GLAST mRNA levels and attenuated the Mn-induced inhibition of GLAST mRNA expression. In addition, E2 and TX effectively increased the expression of transforming growth factor beta1, a potential modulator of the stimulatory effects of E2/TX on glutamate transporter function. This effect was mediated by the activation of MAPK/extracellular signal-regulated kinase (ERK) and phosphoinositide 3-kinase (PI3K)/Akt signaling pathways. These novel findings suggest, for the first time, that E2 and TX enhance astrocytic glutamate transporter expression via increased transforming growth factor beta1 expression. Furthermore, the present study is the first to show that both E2 and TX effectively reverse Mn-induced glutamate transport inhibition by restoring its expression and activity, thus offering a potential therapeutic modality in neurodegenerative disorders characterized by altered glutamate homeostasis.

  17. Synthesis of a high-valent, four-coordinate manganese cubane cluster with a pendant Mn atom: photosystem II-inspired manganese-nitrogen clusters.

    PubMed

    Vaddypally, Shivaiah; Kondaveeti, Sandeep K; Zdilla, Michael J

    2012-04-02

    High-valent, four-coordinate manganese imido- and nitrido-bridged heterodicubane clusters have been prepared and characterized by single-crystal X-ray diffraction and spectroscopic techniques. The title compound, a corner-nitride-fused dicubane with the chemical formula [Mn(5)Li(3)(μ(6)-N)(N)(μ(3)-N(t)Bu)(6)(μ-N(t)Bu)(3)(N(t)Bu)] (1), has been prepared as an adduct with a nearly isostructural tetramanganese cluster with one Mn atom replaced by Li. An important feature of the reported chemistry is the formation of nitride from tert-butylamide, indicative of N-C bond cleavage facilitated by manganese.

  18. Determining the Role of Multicopper Oxidases in Manganese(II) Oxidation by Marine Bacillus Spores

    NASA Astrophysics Data System (ADS)

    Dick, G. J.; Tebo, B. M.

    2005-12-01

    Bacteria play an important role in the environmental cycling of Mn by oxidizing soluble Mn(II) and forming insoluble Mn(III/IV) oxides. These biogenic Mn oxides are renowned for their strong sorptive and oxidative properties, which control the speciation and availability of many metals and organic compounds. A wide variety of bacteria are known to catalyze the oxidation of Mn(II); one of the most frequently isolated types are Bacillus species that oxidize Mn(II) only as metabolically dormant spores. We are using genetic and biochemical methods to study the molecular mechanisms of this process in these organisms. mnxG, a gene related to the multicopper oxidase (MCO) family of enzymes, is required for Mn(II) oxidation in the model organism, Bacillus sp. strain SG-1. Mn(II)-oxidizing activity can be detected in crude protein extracts of the exosporium and as a discrete band in SDS-PAGE gels, however previous attempts to purify or identify this Mn(II)-oxidizing enzyme have failed. A direct link between the Mn(II)-oxidizing enzyme and the MCO gene suspected to encode it has never been made. We used genetic and biochemical methods to investigate the role of the MCO in the mechanism of Mn(II) oxidation. Comparative analysis of the mnx operon from several diverse Mn(II)-oxidizing Bacillus spores revealed that mnxG is the most highly conserved gene in the operon, and that copper binding sites are highly conserved. As with Mn(II) oxidases from other organisms, heterologous expression of the Bacillus mnxG in E. coli did not yield an active Mn(II) oxidase. Purifying sufficient quantities of the native Mn(II) oxidase from Bacillus species for biochemical characterization has proven difficult because the enzyme does not appear to be abundant, and it is highly insoluble. We were able to partially purify the Mn(II) oxidase, and to analyze the active band by in-gel trypsin digestion followed by tandem mass spectrometry (MS/MS). MS/MS spectra provided a conclusive match to mnx

  19. Siderophore-manganese(lll) Interactions. II. Manganite dissolution promoted by desferrioxamine B.

    PubMed

    Duckworth, Owen W; Sposito, Garrison

    2005-08-15

    Recent laboratory and field studies suggest that Mn(lll) forms persistent aqueous complexes with high-affinity ligands. Aqueous Mn(lll) species thus may play a significant but largely unexplored role in biogeochemical processes. One formation mechanism for these species is the dissolution of Mn(lll)-bearing minerals. To investigate this mechanism, we measured the steady-state dissolution rates of manganite (gamma-MnOOH) in the presence of desferrioxamine B (DFOB), a common trihydroxamate siderophore. We find that DFOB dissolves manganite by both reductive and nonreductive reaction pathways. For pH > 6.5, a nonreductive ligand-promoted reaction is the dominant dissolution pathway, with a steady-state dissolution rate proportional to the surface concentration of DFOB. In the absence of reductants, the aqueous Mn(lIl)HDFOB+ complex resulting from dissolution is stable for at least several weeks at circumneutral to alkaline pH and at 25 degrees C. For pH < 6.5, Mn2+ is the dominant aqueous species resulting from manganite dissolution, implicating a reductive dissolution pathway. These results have important implications for the biogeochemical cycling of both manganese and siderophores--as well as Fe(lll)--in natural waters and soils.

  20. Structural oxidation state studies of the manganese cluster in the oxygen evolving complex of photosystem II

    SciTech Connect

    Liang, Wenchuan

    1994-11-01

    X-ray absorption spectroscopy (XAS) was performed on Photosystem II (PSII)-enriched membranes prepared from spinach to explore: (1) the correlation between structure and magnetic spin state of the Mn cluster in the oxygen evolving complex (OEC) in the S2 state; and (2) the oxidation state changes of the Mn cluster in the flash-induced S-states. The structure of the Mn cluster in the S2 state with the g~4 electron paramagnetic resonance (EPR) signal (S2-g4 state) was compared with that in the S2 state with multiline signal (S2-MLS state) and the S1 state. The S2-g4 state has a higher XAS inflection point energy than that of the S1 state, indicating the oxidation of Mn in the advance from the S1 to the S2-g4 state. Differences in the edge shape and in the extended X-ray absorption fine structure (EXAFS) show that the structure of the Mn cluster in the S2-g4 state is different from that in the S2-MLS or the S1 state. In the S2-g4 state, the second shell of backscatterers from the Mn absorber contains two Mn-Mn distances of 2.73 Å and 2.85 Å. Very little distance disorder exists in the second shell of the S1 or S2-MLS states. The third shell of the S2-g4 state at about 3.3 Å also contains increased heterogeneity relative to that of the S2-MLS or the S1 state. Various S-states were prepared at room-temperature by saturating, single-turnover flashes. The flash-dependent oscillation in the amplitude of the MLS was used to characterize the S-state composition and to construct "pure" S-state Mn K-edge spectra. The edge position shifts to higher energy by 1.8 eV upon the S1 → S2 transition.

  1. Deregulation of Mitochondria-Shaping Proteins Opa-1 and Drp-1 in Manganese-Induced Apoptosis

    PubMed Central

    Alaimo, Agustina; Gorojod, Roxana M.; Beauquis, Juan; Muñoz, Manuel J.; Saravia, Flavia; Kotler, Mónica L.

    2014-01-01

    Mitochondria are dynamic organelles that undergo fusion and fission processes. These events are regulated by mitochondria-shaping proteins. Changes in the expression and/or localization of these proteins lead to a mitochondrial dynamics impairment and may promote apoptosis. Increasing evidence correlates the mitochondrial dynamics disruption with the occurrence of neurodegenerative diseases. Therefore, we focused on this topic in Manganese (Mn)-induced Parkinsonism, a disorder associated with Mn accumulation preferentially in the basal ganglia where mitochondria from astrocytes represent an early target. Using MitoTracker Red staining we observed increased mitochondrial network fission in Mn-exposed rat astrocytoma C6 cells. Moreover, Mn induced a marked decrease in fusion protein Opa-1 levels as well as a dramatic increase in the expression of fission protein Drp-1. Additionally, Mn provoked a significant release of high MW Opa-1 isoforms from the mitochondria to the cytosol as well as an increased Drp-1 translocation to the mitochondria. Both Mdivi-1, a pharmacological Drp-1 inhibitor, and rat Drp-1 siRNA reduced the number of apoptotic nuclei, preserved the mitochondrial network integrity and prevented cell death. CsA, an MPTP opening inhibitor, prevented mitochondrial Δψm disruption, Opa-1 processing and Drp-1 translocation to the mitochondria therefore protecting Mn-exposed cells from mitochondrial disruption and apoptosis. The histological analysis and Hoechst 33258 staining of brain sections of Mn-injected rats in the striatum showed a decrease in cellular mass paralleled with an increase in the occurrence of apoptotic nuclei. Opa-1 and Drp-1 expression levels were also changed by Mn-treatment. Our results demonstrate for the first time that abnormal mitochondrial dynamics is implicated in both in vitro and in vivo Mn toxicity. In addition we show that the imbalance in fusion/fission equilibrium might be involved in Mn-induced apoptosis. This knowledge may

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

    PubMed

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

    2016-02-01

    Iron (Fe) deficiency is a widespread nutritional disorder on calcareous soils. To identify genes involved in the Fe deficiency response, Arabidopsis (Arabidopsis thaliana) transfer DNA insertion lines were screened on a high-pH medium with low Fe availability. This approach identified METAL TOLERANCE PROTEIN8 (MTP8), a member of the Cation Diffusion Facilitator family, as a critical determinant for the tolerance to Fe deficiency-induced chlorosis, also on soil substrate. Subcellular localization to the tonoplast, complementation of a manganese (Mn)-sensitive Saccharomyces cerevisiae yeast strain, and Mn sensitivity of mtp8 knockout mutants characterized the protein as a vacuolar Mn transporter suitable to prevent plant cells from Mn toxicity. MTP8 expression was strongly induced on low-Fe as well as high-Mn medium, which were both strictly dependent on the transcription factor FIT, indicating that high-Mn stress induces Fe deficiency. mtp8 mutants were only hypersensitive to Fe deficiency when Mn was present in the medium, which further suggested an Mn-specific role of MTP8 during Fe limitation. Under those conditions, mtp8 mutants not only translocated more Mn to the shoot than did wild-type plants but suffered in particular from critically low Fe concentrations and, hence, Fe chlorosis, although the transcriptional Fe deficiency response was up-regulated more strongly in mtp8. The diminished uptake of Fe from Mn-containing low-Fe medium by mtp8 mutants was caused by an impaired ability to boost the ferric chelate reductase activity, which is an essential process in Fe acquisition. These findings provide a mechanistic explanation for the long-known interference of Mn in Fe nutrition and define the molecular processes by which plants alleviate this antagonism. © 2016 American Society of Plant Biologists. All Rights Reserved.

  3. Deregulation of mitochondria-shaping proteins Opa-1 and Drp-1 in manganese-induced apoptosis.

    PubMed

    Alaimo, Agustina; Gorojod, Roxana M; Beauquis, Juan; Muñoz, Manuel J; Saravia, Flavia; Kotler, Mónica L

    2014-01-01

    Mitochondria are dynamic organelles that undergo fusion and fission processes. These events are regulated by mitochondria-shaping proteins. Changes in the expression and/or localization of these proteins lead to a mitochondrial dynamics impairment and may promote apoptosis. Increasing evidence correlates the mitochondrial dynamics disruption with the occurrence of neurodegenerative diseases. Therefore, we focused on this topic in Manganese (Mn)-induced Parkinsonism, a disorder associated with Mn accumulation preferentially in the basal ganglia where mitochondria from astrocytes represent an early target. Using MitoTracker Red staining we observed increased mitochondrial network fission in Mn-exposed rat astrocytoma C6 cells. Moreover, Mn induced a marked decrease in fusion protein Opa-1 levels as well as a dramatic increase in the expression of fission protein Drp-1. Additionally, Mn provoked a significant release of high MW Opa-1 isoforms from the mitochondria to the cytosol as well as an increased Drp-1 translocation to the mitochondria. Both Mdivi-1, a pharmacological Drp-1 inhibitor, and rat Drp-1 siRNA reduced the number of apoptotic nuclei, preserved the mitochondrial network integrity and prevented cell death. CsA, an MPTP opening inhibitor, prevented mitochondrial Δψm disruption, Opa-1 processing and Drp-1 translocation to the mitochondria therefore protecting Mn-exposed cells from mitochondrial disruption and apoptosis. The histological analysis and Hoechst 33258 staining of brain sections of Mn-injected rats in the striatum showed a decrease in cellular mass paralleled with an increase in the occurrence of apoptotic nuclei. Opa-1 and Drp-1 expression levels were also changed by Mn-treatment. Our results demonstrate for the first time that abnormal mitochondrial dynamics is implicated in both in vitro and in vivo Mn toxicity. In addition we show that the imbalance in fusion/fission equilibrium might be involved in Mn-induced apoptosis. This knowledge may

  4. Manganese carbonates as possible biogenic relics in Archean settings

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  5. [Protective effect of tert-butylhydroquinone on PC12 cells from neurotoxicity induced by manganese in vitro].

    PubMed

    Li, Huang-yuan; Wu, Si-ying; Lin, Wei; Zhou, Wen-hua; Zhang, Wen-chang; Li, Tao; Shi, Nian

    2009-10-01

    To investigate the protective effect of the tert-butylhydroquinone (tBHQ) on PC12 cells from neurotoxicity induced by manganese. Cytotoxicity of PC12 cells was measured by MTT assay, following the PC12 cells treatment with different concentrations of MnCl₂ (300, 600, 900 μmol/L) for 24, 48 or 72 h. PC12 cells were pretreated with 40 μmol/L tBHQ for 12 h, followed by the treatment of 600 micromol/L or 300 μmol/L MnCl₂ for 72 h. Cytotoxicity of PC12 cells was measured by MTT assay, and cell apoptosis was examined by the method of Annexin V-FITC/PI in flow cytometry (FCM). The proliferation of PC12 cells treated with 300, 600, 900 μmol/L MnCl2 was suppressed in the dose dependent pattern (P < 0.01). Proliferation of PC12 cells treated with 600 μmol/L MnCl₂ was suppressed to 40% of that in control group (P < 0.01), but the proliferation rate of PC12 cell pretreated with 40 μmol/L tBHQ was 180% of that in control group (P < 0.01). Apoptotic rate of PC12 cells treated with 300 micromol/L MnCl₂ was higher than the vehicle control group (P < 0.01). Apoptotic rate of 40 μmol/L tBHQ pretreatment followed by 300 μmol/L MnCl₂ treatment was lower than that of MnCl2 treatment group (P < 0.01). The inhibition rate of apoptosis was 61%. Manganese may suppress PC12 cells proliferation and induce apoptosis. tBHQ can reduce PC12 cells proliferation suppressed by manganese and attenuate the apoptosis induced by manganese.

  6. Manganese-induced oxidative stress in two ontogenetic stages of chamomile and amelioration by nitric oxide.

    PubMed

    Kováčik, Jozef; Babula, Petr; Hedbavny, Josef; Švec, Pavel

    2014-02-01

    Impact of manganese (Mn(2+)) excess (100, 500 and 1000 μM over 7 days) on two ontogenetic stages (7-week-old plants and 7-day-old seedlings) of Matricaria chamomilla was compared. Mn excess depressed growth of seedlings (but not germination) and stimulated oxidative stress (ROS and lipid peroxidation) in both plants and seedlings. Growth inhibition could be evoked by higher Mn uptake and higher translocation factor in seedlings than in plants. Total thiols staining revealed elevation in almost all treatments. In 7-week-old plants, activity of peroxidases increased slightly and rather decreased under high Mn doses. Superoxide rather than hydrogen peroxide contributed to visualized ROS presence. Fluorescence of nitric oxide (NO) showed stimulation in plants but decrease in seedlings. Impact of exogenous nitric oxide donor (sodium nitroprusside/SNP) was therefore tested and results showed amelioration of 1000 μM Mn-induced oxidative stress in seedlings (decrease in H2O2 and increase in NO content while antioxidative enzyme activities were variably affected) concomitantly with depleted Mn accumulation. It is concluded that NO participates in tolerance to Mn excess but negative effects of the highest SNP dose were also observed. Extensive fluorescence microscopy is also explanatively discussed. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  7. Changes in Lipid Composition During Manganese-Induced Apoptosis in PC12 Cells.

    PubMed

    Corsetto, P A; Ferrara, G; Buratta, S; Urbanelli, L; Montorfano, G; Gambelunghe, A; Chiaradia, E; Magini, A; Roderi, P; Colombo, I; Rizzo, A M; Emiliani, C

    2016-02-01

    Lipid composition of membranes is fundamental to modulate signaling pathways relying on lipid metabolites and/or membrane proteins, thus resulting in the regulation of important cell processes such as apoptosis. In this case, membrane remodeling is an early event important for the activation of signaling leading to cell death and removal of apoptotic cells. In the present study, we analyzed phospholipid, cholesterol and fatty acid content during apoptosis induced by manganese in PC12 cells. Lipid analysis of whole cells and detergent-resistant membranes was carried out by HPLC/GC. Results showed that apoptosis is associated with changes in lipid composition detectable in whole cell extracts, namely cholesterol, phosphatidylserine and phosphatidylethanolamine decreases. Noteworthy, phosphatidylserine level reduction was detectable before to the detection of apoptosis, in correlation with our previous study carried out by radioactive labelling. By contrast, phosphatidylserine and phosphatidylethanolamine changes were not detected in detergent resistant membranes, which instead showed an altered composition in phosphatidylinositol, phosphatidylcholine and sphingomyelin in apoptotic cells.

  8. Estrogen attenuates manganese-induced glutamate transporter impairment in rat primary astrocytes.

    PubMed

    Lee, Eunsook; Sidoryk-Wegrzynowicz, Marta; Farina, Marcelo; Rocha, Joao B T; Aschner, Michael

    2013-02-01

    The astrocytic glutamate transporters (GLT-1, GLAST) are critical for removing excess glutamate from synaptic sites, thereby maintaining glutamate homeostasis within the brain. 17β-Estradiol (E2) is one of the most active estrogen hormones possessing neuroprotective effects both in in vivo and in vitro models, and it has been shown to enhance astrocytic glutamate transporter function (Liang et al. in J Neurochem 80:807-814, 2002; Pawlak et al. in Brain Res Mol Brain Res 138:1-7, 2005). However, E2 is not clinically optimal for neuroprotection given its peripheral feminizing and proliferative effects; therefore, brain selective estrogen receptor modulators (neuro SERMs) (Zhao et al. in Neuroscience 132:299-311, 2005) that specifically target estrogenic mechanisms, but lack the systemic estrogen side effects offer more promising therapeutic modality for the treatment of conditions associated with excessive synaptic glutamate levels. This review highlights recent studies from our laboratory showing that E2 and SERMs effectively reverse glutamate transport inhibition in a manganese (Mn)-induced model of glutamatergic deregulation. Specifically, we discuss mechanisms by which E2 restores the expression and activity of glutamate uptake. We advance the hypothesis that E2 and related compounds, such as tamoxifen may offer a potential therapeutic modality in neurodegenerative disorders, which are characterized by altered glutamate homeostasis.

  9. Estrogen attenuates Manganese-induced glutamate transporter impairment in rat primary astrocytes

    PubMed Central

    Lee, Eunsook; Sidoryk-Wegrzynowicz, Marta; Farina, Marcelo; Rocha, Joao BT; Aschner, Michael

    2012-01-01

    The astrocytic glutamate transporters (GLT-1, GLAST) are critical for removing excess glutamate from synaptic sites, thereby maintaining glutamate homeostasis within the brain. 17 -Estradiol (E2) is one of the most active estrogen hormones possessing neuroprotective effects both in in vivo and in vitro models, and it has been shown to enhance astrocytic glutamate transporter function (Liang et al. 2002; Pawlak et al. 2005). However, E2 is not clinically optimal for neuroprotection given its peripheral feminizing and proliferative effects; therefore, brain selective estrogen receptor modulators (neuroSERMs) (Zhao et al. 2005) that specifically target estrogenic mechanisms, but lack the systemic estrogen side effects offer more promising therapeutic modality for the treatment of conditions associated with excessive synaptic glutamate levels. This review highlights recent studies from our laboratory showing that E2 and SERMs effectively reverse glutamate transport inhibition in a manganese (Mn)-induced model of glutamatergic deregulation. Specifically, we discuss mechanisms by which E2 restores the expression and activity of glutamatergic neurotransmission. We advance the hypothesis that E2 and related compounds, such as tamoxifen (TX) may offer a potential therapeutic modality in neurodegenerative disorders, which are characterized by altered glutamate homeostasis. PMID:22878846

  10. Manganese exposure induces α-synuclein aggregation in the frontal cortex of non-human primates.

    PubMed

    Verina, Tatyana; Schneider, Jay S; Guilarte, Tomás R

    2013-03-13

    Aggregation of α-synuclein (α-syn) in the brain is a defining pathological feature of neurodegenerative disorders classified as synucleinopathies. They include Parkinson's disease (PD), dementia with Lewy bodies (DLB), and multiple system atrophy (MSA). Occupational and environmental exposure to manganese (Mn) is associated with a neurological syndrome consisting of psychiatric symptoms, cognitive impairment and parkinsonism. In this study, we examined α-syn immunoreactivity in the frontal cortex of Cynomolgus macaques as part of a multidisciplinary assessment of the neurological effects produced by exposure to moderate levels of Mn. We found increased α-syn-positive cells in the gray matter of Mn-exposed animals, typically observed in pyramidal and medium-sized neurons in deep cortical layers. Some of these neurons displayed loss of Nissl staining with α-syn-positive spherical aggregates. In the white matter we also observed α-syn-positive glial cells and in some cases α-syn-positive neurites. These findings suggest that Mn exposure promotes α-syn aggregation in neuronal and glial cells that may ultimately lead to degeneration in the frontal cortex gray and white matter. To our knowledge, this is the first report of Mn-induced neuronal and glial cell α-syn accumulation and aggregation in the frontal cortex of non-human primates.

  11. Manganese induces mitochondrial dynamics impairment and apoptotic cell death: a study in human Gli36 cells.

    PubMed

    Alaimo, Agustina; Gorojod, Roxana M; Miglietta, Esteban A; Villarreal, Alejandro; Ramos, Alberto J; Kotler, Mónica L

    2013-10-25

    Manganese (Mn) is an essential trace element due to its participation in many physiological processes. However, overexposure to this metal leads to a neurological disorder known as Manganism whose clinical manifestations and molecular mechanisms resemble Parkinson's disease. Several lines of evidence implicate astrocytes as an early target of Mn neurotoxicity being the mitochondria the most affected organelles. The aim of this study was to investigate the possible mitochondrial dynamics alterations in Mn-exposed human astrocytes. Therefore, we employed Gli36 cells which express the astrocytic markers GFAP and S100B. We demonstrated that Mn triggers the mitochondrial apoptotic pathway revealed by increased Bax/Bcl-2 ratio, by the loss of mitochondrial membrane potential and by caspase-9 activation. This apoptotic program may be in turn responsible of caspase-3/7 activation, PARP-1 cleavage, chromatin condensation and fragmentation. In addition, we determined that Mn induces deregulation in mitochondria-shaping proteins (Opa-1, Mfn-2 and Drp-1) expression levels in parallel with the disruption of the mitochondrial network toward to an exacerbated fragmentation. Since mitochondrial dynamics is altered in several neurodegenerative diseases, these proteins could become future targets to be considered in Manganism treatment. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  12. Interplay between lysosomal, mitochondrial and death receptor pathways during manganese-induced apoptosis in glial cells.

    PubMed

    Gorojod, R M; Alaimo, A; Porte Alcon, S; Saravia, F; Kotler, M L

    2017-04-04

    Manganese (Mn) is an essential trace metal which plays a critical role in brain physiology by acting as a cofactor for several enzymes. However, upon overexposure, Mn preferentially accumulates within the basal ganglia leading to the development of a Parkinsonism known as Manganism. Data from our group have proved that Mn induces oxidative stress-mediated apoptosis in astrocytoma C6 cells. In the present study we described how cathepsins impact on different steps of each apoptotic cascade. Evidence obtained demonstrated that Mn generates lysosomal membrane permeabilization (LMP) and cathepsin release. Both cathepsins B (Ca-074 Me) and D (Pepstatin A) inhibitors as well as Bafilomycin A1 prevented caspases-3, -7, -8 and -9 activation, FasL upregulation, Bid cleavage, Δφm disruption and cytochrome c release. Results from in vivo studies showed that intrastriatal Mn injection increased cathepsin D levels from corpus striatum and substantia nigra pars compacta. Our results point to LMP and lysosomal cathepsins as key mediators in the apoptotic process triggered by Mn. These findings highlight the relevance of targeting the lysosomal pathway for Manganism therapy.

  13. Chemiluminescence accompanied by the reaction of acridinium ester and manganese (II).

    PubMed

    Ren, Lingling; Cui, Hua

    2014-11-01

    An acridinium ester (AE) alkaline solution can react with Mn(II) to generate a strong chemiluminescence (CL) centered at 435 nm. The effects of reaction conditions such as pH and Mn(II) concentration on CL intensity were examined. In order to explore the CL mechanism, the effect of oxygen on the CL reaction was examined and an X-ray photoelectron spectroscopy study of the reaction precipitate was carried out. The results indicated that oxygen participated in the CL reaction and Mn(IV) was the primary product in the system. A possible mechanism was proposed that involved two pathways: (1) dissolved oxygen was reduced to reactive oxygen radicals by Mn(II), these reactive intermediates then reacted with AE to produce excited state acridone; (2) Mn(II) could reduce AE to partly reduced AE, which then reacted with oxygen to form excited state acridone. The reactions of other metal ions with AE were also tested, and only Mn(II) was shown to trigger strong CL emission of AE, which indicated that the system had good selectivity for Mn(II).

  14. Vacancy-induced manganese vanadates and their potential application to Li-ion batteries.

    PubMed

    Dufficy, Martin K; Luo, Lan; Fedkiw, Peter S; Maggard, Paul A

    2016-06-14

    We report on the synthesis and characterization of a novel manganese vanadate, Mn1.5(H2O)(NH4)V4O12, with rare in situ disorder of Mn(H2O)2(2+)/2NH4(+). We show that vacancies created by ammonium ions and coordinating water molecules within the manganese vanadate crystal structure yield high-charge capacity, favorable rate capability, and long cycle life in Li-ion half-cells.

  15. Manganese(II) chloride alters behavioral and neurochemical parameters in larvae and adult zebrafish.

    PubMed

    Altenhofen, Stefani; Wiprich, Melissa Talita; Nery, Laura Roesler; Leite, Carlos Eduardo; Vianna, Monica Ryff Moreira Roca; Bonan, Carla Denise

    2017-01-01

    Manganese (Mn) is an essential metal for organisms, but high levels can cause serious neurological damage. The aim of this study was to evaluate the effects of MnCl2 exposure on cognition and exploratory behavior in adult and larval zebrafish and correlate these findings with brain accumulation of Mn, overall brain tyrosine hydroxylase (TH) levels, dopamine (DA) levels, 3,4-dihydroxyphenylacetic acid (DOPAC) levels and cell death markers in the nervous system. Adults exposed to MnCl2 for 4days (0.5, 1.0 and 1.5mM) and larvae exposed for 5days (0.1, 0.25 and 0.5mM) displayed decreased exploratory behaviors, such as distance traveled and absolute body turn angle, in addition to reduced movement time and an increased number of immobile episodes in larvae. Adults exposed to MnCl2 for 4days showed impaired aversive long-term memory in the inhibitory avoidance task. The overall brain TH levels were elevated in adults and larvae evaluated at 5 and 7 days post-fertilization (dpf). Interestingly, the protein level of this enzyme was decreased in larval animals at 10dpf. Furthermore, DOPAC levels were increased in adult animals exposed to MnCl2. Protein analysis showed increased apoptotic markers in both the larvae and adult nervous system. The results demonstrated that prolonged exposure to MnCl2 leads to locomotor deficits that may be associated with damage caused by this metal in the CNS, particularly in the dopaminergic system.

  16. Description of the first fungal dye-decolorizing peroxidase oxidizing manganese(II).

    PubMed

    Fernández-Fueyo, Elena; Linde, Dolores; Almendral, David; López-Lucendo, María F; Ruiz-Dueñas, Francisco J; Martínez, Angel T

    2015-11-01

    Two phylogenetically divergent genes of the new family of dye-decolorizing peroxidases (DyPs) were found during comparison of the four DyP genes identified in the Pleurotus ostreatus genome with over 200 DyP genes from other basidiomycete genomes. The heterologously expressed enzymes (Pleos-DyP1 and Pleos-DyP4, following the genome nomenclature) efficiently oxidize anthraquinoid dyes (such as Reactive Blue 19), which are characteristic DyP substrates, as well as low redox-potential dyes (such as 2,2-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid)) and substituted phenols. However, only Pleos-DyP4 oxidizes the high redox-potential dye Reactive Black 5, at the same time that it displays high thermal and pH stability. Unexpectedly, both enzymes also oxidize Mn(2+) to Mn(3+), albeit with very different catalytic efficiencies. Pleos-DyP4 presents a Mn(2+) turnover (56 s(-1)) nearly in the same order of the two other Mn(2+)-oxidizing peroxidase families identified in the P. ostreatus genome: manganese peroxidases (100 s(-1) average turnover) and versatile peroxidases (145 s(-1) average turnover), whose genes were also heterologously expressed. Oxidation of Mn(2+) has been reported for an Amycolatopsis DyP (24 s(-1)) and claimed for other bacterial DyPs, albeit with lower activities, but this is the first time that Mn(2+) oxidation is reported for a fungal DyP. Interestingly, Pleos-DyP4 (together with ligninolytic peroxidases) is detected in the secretome of P. ostreatus grown on different lignocellulosic substrates. It is suggested that generation of Mn(3+) oxidizers plays a role in the P. ostreatus white-rot lifestyle since three different families of Mn(2+)-oxidizing peroxidase genes are present in its genome being expressed during lignocellulose degradation.

  17. Description of the first fungal dye-decolorizing peroxidase oxidizing manganese(II)

    DOE PAGES

    Fernandez-Fueyo, Elena; Linde, Dolores; Almendral, David; ...

    2015-05-13

    Two phylogenetically divergent genes of the new family of dye-decolorizing peroxidases (DyPs) were found during comparison of the four DyP genes identified in the Pleurotus ostreatus genome with over 200 DyP genes from other basidiomycete genomes. The heterologously expressed enzymes (Pleos-DyP1 and Pleos-DyP4, following the genome nomenclature) efficiently oxidize anthraquinoid dyes (such as Reactive Blue 19), which are characteristic DyP substrates, as well as low redox-potential dyes (such as 2,2-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid)) and substituted phenols. However, only Pleos-DyP4 oxidizes the high redox-potential dye Reactive Black 5, at the same time that it displays high thermal and pH stability. Unexpectedly, both enzymesmore » also oxidize Mn2+ to Mn3+, albeit with very different catalytic efficiencies. Pleos-DyP4 presents a Mn2+ turnover (56 s–1) nearly in the same order of the two other Mn2+-oxidizing peroxidase families identified in the P. ostreatus genome: manganese peroxidases (100 s–1 average turnover) and versatile peroxidases (145 s–1 average turnover), whose genes were also heterologously expressed. Oxidation of Mn2+ has been reported for an Amycolatopsis DyP (24 s–1) and claimed for other bacterial DyPs, albeit with lower activities, but this is the first time that Mn2+ oxidation is reported for a fungal DyP. Interestingly, Pleos-DyP4 (together with ligninolytic peroxidases) is detected in the secretome of P. ostreatus grown on different lignocellulosic substrates. In conclusion, it is suggested that generation of Mn3+ oxidizers plays a role in the P. ostreatus white-rot lifestyle since three different families of Mn2+-oxidizing peroxidase genes are present in its genome being expressed during lignocellulose degradation.« less

  18. Attenuation of Combined Nickel(II) Oxide and Manganese(II, III) Oxide Nanoparticles’ Adverse Effects with a Complex of Bioprotectors

    PubMed Central

    Minigalieva, Ilzira A.; Katsnelson, Boris A.; Privalova, Larisa I.; Sutunkova, Marina P.; Gurvich, Vladimir B.; Shur, Vladimir Y.; Shishkina, Ekaterina V.; Valamina, Irene E.; Makeyev, Oleg H.; Panov, Vladimir G.; Varaksin, Anatoly N.; Grigoryeva, Ekaterina V.; Meshtcheryakova, Ekaterina Y.

    2015-01-01

    Stable suspensions of NiO and Mn3O4 nanoparticles (NPs) with a mean (±s.d.) diameter of 16.7 ± 8.2 and 18.4 ± 5.4 nm, respectively, purposefully prepared by laser ablation of 99.99% pure nickel or manganese in de-ionized water, were repeatedly injected intraperitoneally (IP) to rats at a dose of 2.5 mg/kg 3 times a week up to 18 injections, either alone or in combination. A group of rats was injected with this combination with the background oral administration of a “bio-protective complex” (BPC) comprising pectin, vitamins A, C, E, glutamate, glycine, N-acetylcysteine, selenium, iodide and omega-3 PUFA, this composition having been chosen based on mechanistic considerations and previous experience. After the termination of injections, many functional and biochemical indices and histopathological features (with morphometric assessment) of the liver, spleen, kidneys and brain were evaluated for signs of toxicity. The Ni and Mn content of these organs was measured with the help of the atomic emission and electron paramagnetic resonance spectroscopies. We obtained blood leukocytes for performing the RAPD (Random Amplified Polymorphic DNA) test. Although both metallic NPs proved adversely bio-active in many respects considered in this study, Mn3O4-NPs were somewhat more noxious than NiO-NPs as concerns most of the non-specific toxicity manifestations and they induced more marked damage to neurons in the striatum and the hippocampus, which may be considered an experimental correlate of the manganese-induced Parkinsonism. The comparative solubility of the Mn3O4-NPs and NiO-NPs in a biological medium is discussed as one of the factors underlying the difference in their toxicokinetics and toxicities. The BPC has attenuated both the organ-systemic toxicity and the genotoxicity of Mn3O4-NPs in combination with NiO-NPs. PMID:26393577

  19. Manganese Dioxide nanosheet suspension: A novel absorbent for Cadmium(II) contamination in waterbody.

    PubMed

    Peng, Liang; Zeng, Qingru; Tie, Boqing; Lei, Ming; Yang, Jiao; Luo, Si; Song, Zhengguo

    2015-10-15

    A MnO2 nanosheet (MnO2-NS) suspension was prepared from tetramethylammonium hydroxide (TMA⋅OH), H2O2, and MnCl2⋅4H2O, and its efficiency for Cd(II) removal from aqueous solutions was investigated. The maximum adsorption capacity of the MnO2-NS for Cd(II) was evaluated to be about 348 mg/g, which is thus far the highest value reported for MnO2 at pH 6.0. This high adsorption capacity is attributed to efficient ion exchange. X-ray photoelectron spectroscopy (XPS) revealed that Cd(II) was adsorbed on MnO2 as CdO and Cd(OH)2. After Cd(II) adsorption, the suspended MnO2-NS aggregated and precipitated within 5.0 min from solution. Therefore, dispersive MnO2-NS can be used to remove Cd(II) from wastewater rapidly and with high efficiency.

  20. Valence Tautomerization of High-Valent Manganese(V)-Oxo Corrole Induced by Protonation of the Oxo Ligand.

    PubMed

    Bougher, Curt J; Liu, Shuo; Hicks, Scott D; Abu-Omar, Mahdi M

    2015-11-18

    The addition of an organic acid to the manganese(V)-oxo corrole complex (tpfc)Mn(V)(O) (tpfc = 5,10,15-tris(pentafluorophenyl)corrole) induces valence tautomerization resulting in the formation of (tpfc(+•))Mn(IV)(OH) in acetonitrile at 298 K. The corrole radical cation manganese(IV) hydroxo complex has been fully characterized by EPR, (1)H NMR, and UV-vis spectroscopy. The reactivity of the valence tautomer (tpfc(+•))Mn(IV)(OH) is compared to that of (tpfc)Mn(V)(O) in three reaction types: hydrogen atom transfer (HAT), electron transfer (ET), and oxygen atom transfer (OAT). (tpfc(+•))Mn(IV)(OH) shows a dramatic 5 orders of magnitude enhancement in the rate of ET but surprisingly does not undergo OAT with PhSMe. The high-valent (tpfc)Mn(V)(O) complex is moderately more reactive toward HAT with substituted phenol and shows superior activity in OAT.

  1. A novel manganese complex selectively induces malignant glioma cell death by targeting mitochondria.

    PubMed

    Geng, Ji; Li, Jing; Huang, Tao; Zhao, Kaidi; Chen, Qiuyun; Guo, Wenjie; Gao, Jing

    2016-09-01

    Despite advances in treatment, malignant glioma commonly exhibits recurrence, subsequently leading to a poor prognosis. As manganese (Mn) compounds can be transported by the transferrin‑transferrin receptor system, the present study synthesized and examined the potential use of Adpa‑Mn as a novel antitumor agent. Adpa‑Mn time and dose‑dependently inhibited U251 and C6 cell proliferation; however, it had little effect on normal astrocytes. Apoptosis was significantly elevated following treatment with Adpa‑Mn, as detected by chromatin condensation, Annexin V/propidium iodide staining, cytochrome c release from mitochondria to the cytoplasm, and the activation of caspases‑9, ‑7 and ‑3 and poly (ADP‑ribose) polymerase. In addition, Adpa‑Mn enhanced fluorescence intensity of monodansylcadaverine and elevated the expression levels of the autophagy‑related protein microtubule‑associated protein 1 light chain 3. Pretreatment with the autophagy inhibitors 3‑methyladenine and chloroquine enhanced Adpa‑Mn‑induced cell inhibition, thus indicating that autophagy has an essential role in this process. Furthermore, evidence of mitochondrial dysfunction was detected in the Adpa‑Mn‑treated group, including disrupted membrane potential, elevated levels of reactive oxygen species (ROS) and depleted adenosine triphosphate. Conversely, treatment with the mitochondrial permeability transition inhibitor cyclosporin A reversed Adpa‑Mn‑induced ROS production, mitochondrial damage and cell apoptosis, thus suggesting that Adpa‑Mn may target the mitochondria. Taken together, these data suggested that Adpa‑Mn may be considered for use as a novel anti‑glioma therapeutic option.

  2. The effects of manganese (II) but not nickel (II) ions on Enterococcus hirae cell growth, redox potential decrease, and proton-coupled membrane transport.

    PubMed

    Vardanyan, Zaruhi; Trchounian, Armen

    2013-01-01

    Enterococcus hirae grow well under anaerobic conditions by fermenting glucose, accompanied with the decrease of oxidation-reduction potential (Eh) from positive values to negative ones. It was shown that heavy metals-copper and iron ions-affect E. hirae growth and alter Eh and proton-potassium ions fluxes through the cell membrane. The aim of this study was to establish the effects of manganese (II) ions on bacterial growth within the concentration range of 0.01-1 mM and compare with nickel (II) ions' effect. The presence of Mn(2+) during E. hirae ATCC9790 growth had significant effects: The lag phase duration decreased while the specific growth rate was increased; decrease in E h was shifted. In contrast, no visible changes in bacterial growth and Eh were observed in the case of Ni(2+). The effects of these ions on proton-potassium ions fluxes through the cell membrane were estimated in the presence and absence of N,N'-dicyclohexylcarbodiimide (DCCD), inhibitor of the FoF1 ATPase. Stronger effect of Mn(2+) on H(+)-K(+) exchange was detected in the presence of DCCD that can be explained by a possible complex formation between these substances and its direct influence on membrane transport proteins.

  3. The water soluble peripherally tetra-substituted zinc(ii), manganese(iii) and copper(ii) phthalocyanines as new potential anticancer agents.

    PubMed

    Barut, Burak; Sofuoğlu, Ayşenur; Biyiklioglu, Zekeriya; Özel, Arzu

    2016-09-28

    In this study, [2-(2-morpholin-4-ylethoxy)ethoxy] group substituted zinc(ii), manganese(iii) and copper(ii) phthalocyanines 2-4 and their water soluble derivatives 2a, 3a and 4a were synthesized and the interactions of compounds 2a, 3a and 4a with CT-DNA and supercoiled pBR322 plasmid DNA were investigated. The results of binding experiments showed that these compounds were able to interact with CT-DNA via intercalative mode with a strong binding affinity in the order 3a > 2a > 4a. DNA-photocleavage activities of compounds 2a, 3a and 4a were determined. These compounds cleaved supercoiled pBR322 plasmid DNA efficiently under irradiation at 650 nm for 2a and 4a, and at 750 nm for 3a. These compounds displayed remarkable inhibitory activities against topoisomerase I enzyme in a dose-dependent manner. All of these results suggest that these phthalocyanines might be suitable anticancer agents due to their strong binding affinities, significant cleavage activities and effective topoisomerase I inhibition.

  4. Pulsed-EPR evidence of a manganese(II) hydroxycarbonyl intermediate in the electrocatalytic reduction of carbon dioxide by a manganese bipyridyl derivative.

    PubMed

    Bourrez, Marc; Orio, Maylis; Molton, Florian; Vezin, Hervé; Duboc, Carole; Deronzier, Alain; Chardon-Noblat, Sylvie

    2014-01-03

    A key intermediate in the electroconversion of carbon dioxide to carbon monoxide, catalyzed by a manganese tris(carbonyl) complex, is characterized. Different catalytic pathways and their potential reaction mechanisms are investigated using a large range of experimental and computational techniques. Sophisticated spectroscopic methods including UV/Vis absorption and pulsed-EPR techniques (2P-ESEEM and HYSCORE) were combined together with DFT calculations to successfully identify a key intermediate in the catalytic cycle of CO2 reduction. The results directly show the formation of a metal-carboxylic acid-CO2 adduct after oxidative addition of CO2 and H(+) to a Mn(0) carbonyl dimer, an unexpected intermediate.

  5. Manganese(II) Complexes with Schiff Bases Immobilized on Nanosilica as Catalysts of the Reaction of Ozone Decomposition.

    PubMed

    Rakytska, Tetyana; Truba, Alla; Radchenko, Evgen; Golub, Alexander

    2015-12-01

    In this article, we submit the description of synthesis and identification of manganese(II) complexes with pyrogenic nanosilica-immobilized (d av = 10 nm; S sp = 290 m(2)/g) hydroxyaldimine ligands [Formula: see text]: salicilaldiminopropyl (L1); 5-bromosalicilaldiminopropyl (L2); 2-hydroxynaphtaldiminopropyl (L3); 2-hydroxy-3-methoxybenzaldiminopropyl (L4); 2-hydroxy-3,5-dichloroacetophenoniminopropyl (L5); and 4-hydroxy-3-methoxybenzaldiminopropyl (L6). The ligands and complexes were characterized by UV-VIS and IR spectrometry. Nanocomposites consisting of complexes [Formula: see text] showed a high catalytic activity in low-temperature ozone decomposition in the range of concentrations between 2.1 × 10(-6) and 8.4 × 10(-6) mol/l. The number of catalytic cycles increased for isostructural pseudotetrahedral complexes [Formula: see text] (L1-L5) in the following order: Mn(L3)2 > Mn(L4)2 > Mn(L1)2 > Mn(L2)2 > Mn(L5)2. In the case of pseudooctahedral complexes with L6, the change of coordination polyhedral does not influence the kinetics and stoichiometric parameters of the reaction.

  6. Manganese(II) Complexes with Schiff Bases Immobilized on Nanosilica as Catalysts of the Reaction of Ozone Decomposition

    NASA Astrophysics Data System (ADS)

    Rakytska, Tetyana; Truba, Alla; Radchenko, Evgen; Golub, Alexander

    2015-12-01

    In this article, we submit the description of synthesis and identification of manganese(II) complexes with pyrogenic nanosilica-immobilized ( d av = 10 nm; S sp = 290 m2/g) hydroxyaldimine ligands (Mn{(L)}_2/overline{Si}) : salicilaldiminopropyl (L1); 5-bromosalicilaldiminopropyl (L2); 2-hydroxynaphtaldiminopropyl (L3); 2-hydroxy-3-methoxybenzaldiminopropyl (L4); 2-hydroxy-3,5-dichloroacetophenoniminopropyl (L5); and 4-hydroxy-3-methoxybenzaldiminopropyl (L6). The ligands and complexes were characterized by UV-VIS and IR spectrometry. Nanocomposites consisting of complexes Mn{(L)}_2/overline{Si} showed a high catalytic activity in low-temperature ozone decomposition in the range of concentrations between 2.1 × 10-6 and 8.4 × 10-6 mol/l. The number of catalytic cycles increased for isostructural pseudotetrahedral complexes Mn{(L)}_2/overline{Si} (L1-L5) in the following order: Mn(L3)2 >> Mn(L4)2 > Mn(L1)2 > Mn(L2)2 > Mn(L5)2. In the case of pseudooctahedral complexes with L6, the change of coordination polyhedral does not influence the kinetics and stoichiometric parameters of the reaction.

  7. Multifrequency Pulsed EPR Studies of Biologically Relevant Manganese(II) Complexes

    PubMed Central

    Stich, T. A.; Lahiri, S.; Yeagle, G.; Dicus, M.; Brynda, M.; Gunn, A.; Aznar, C.; DeRose, V. J.; Britt, R. D.

    2011-01-01

    Electron paramagnetic resonance studies at multiple frequencies (MF EPR) can provide detailed electronic structure descriptions of unpaired electrons in organic radicals, inorganic complexes, and metalloenzymes. Analysis of these properties aids in the assignment of the chemical environment surrounding the paramagnet and provides mechanistic insight into the chemical reactions in which these systems take part. Herein, we present results from pulsed EPR studies performed at three different frequencies (9, 31, and 130 GHz) on [Mn(II)(H2O)6]2+, Mn(II) adducts with the nucleotides ATP and GMP, and the Mn(II)-bound form of the hammerhead ribozyme (MnHH). Through line shape analysis and interpretation of the zero-field splitting values derived from successful simulations of the corresponding continuous-wave and field-swept echo-detected spectra, these data are used to exemplify the ability of the MF EPR approach in distinguishing the nature of the first ligand sphere. A survey of recent results from pulsed EPR, as well as pulsed electron-nuclear double resonance and electron spin echo envelope modulation spectroscopic studies applied to Mn(II)-dependent systems, is also presented. PMID:22190766

  8. Honeycomb-like S = 5/2 Spin-Lattices in Manganese(II) Vanadates.

    PubMed

    Sanjeewa, Liurukara D; McGuire, Michael A; McMillen, Colin D; Willett, Daniel; Chumanov, George; Kolis, Joseph W

    2016-09-19

    New complex manganese vanadate materials were synthesized as high-quality single crystals in multi-millimeter lengths using a high-temperature, high-pressure hydrothermal method. One compound, Mn5(VO4)2(OH)4, was grown from Mn2O3 and V2O5 in 3 M CsOH at 580 °C and 1.5 kbar. Changing the mineralizer to 1 M CsOH/3MCsCl leads to the formation of another product, Mn6O(VO4)2(OH). Both compounds were structurally characterized by single-crystal X-ray diffraction (Mn5(VO4)2(OH)4: C2/m, Z = 2, a = 9.6568(9) Å, b = 9.5627(9) Å, c = 5.4139(6) Å, β = 98.529(8)°; Mn6O(VO4)2(OH): P21/m, Z = 2, a = 8.9363(12) Å, b = 6.4678(8) Å, c = 10.4478(13) Å, β = 99.798(3)°), revealing interesting low-dimensional transition-metal features. Mn5(VO4)2(OH)4 possesses complex honeycomb-type Mn-O layers, built from edge-sharing [MnO6] octahedra in the bc plane, with bridging vanadate groups connecting these layers along the a-axis. Mn6O(VO4)2(OH) presents a more complicated structure with both octahedral [MnO6] and trigonal bipyramidal [MnO5] units. A different pattern of planar honeycomb sheets are formed by edge-shared [MnO6] octahedra, and these sublattices are connected through edge-shared dimers of [MnO5] trigonal bipyramids to form corrugated sheets. Vanadate groups again condense the sheets into a three-dimensional framework. Infrared and Raman spectroscopies indicated the presence of OH groups and displayed characteristic Raman scattering due to vanadate groups. Temperature-dependent magnetic studies indicated Curie-Weiss behavior above 100 K with significant anti-ferromagnetic coupling for both compounds, with further complex magnetic behavior at lower temperatures. The data indicate canted anti-ferromagnetic order below 57 K in Mn5(VO4)2(OH)4 and below 45 K in Mn6O(VO4)2(OH). Members of another class of compounds, K2M3(VO4)2(OH)2 (M = Mn, Co), also containing a honeycomb-type sublattice, were also synthesized to allow a comparison of the structural features across all three

  9. Description of the first fungal dye-decolorizing peroxidase oxidizing manganese(II)

    SciTech Connect

    Fernandez-Fueyo, Elena; Linde, Dolores; Almendral, David; Lopez-Lucendo, María F.; Ruiz-Duenas, Francisco J.; Martinez, Angel T.

    2015-05-13

    Two phylogenetically divergent genes of the new family of dye-decolorizing peroxidases (DyPs) were found during comparison of the four DyP genes identified in the Pleurotus ostreatus genome with over 200 DyP genes from other basidiomycete genomes. The heterologously expressed enzymes (Pleos-DyP1 and Pleos-DyP4, following the genome nomenclature) efficiently oxidize anthraquinoid dyes (such as Reactive Blue 19), which are characteristic DyP substrates, as well as low redox-potential dyes (such as 2,2-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid)) and substituted phenols. However, only Pleos-DyP4 oxidizes the high redox-potential dye Reactive Black 5, at the same time that it displays high thermal and pH stability. Unexpectedly, both enzymes also oxidize Mn2+ to Mn3+, albeit with very different catalytic efficiencies. Pleos-DyP4 presents a Mn2+ turnover (56 s–1) nearly in the same order of the two other Mn2+-oxidizing peroxidase families identified in the P. ostreatus genome: manganese peroxidases (100 s–1 average turnover) and versatile peroxidases (145 s–1 average turnover), whose genes were also heterologously expressed. Oxidation of Mn2+ has been reported for an Amycolatopsis DyP (24 s–1) and claimed for other bacterial DyPs, albeit with lower activities, but this is the first time that Mn2+ oxidation is reported for a fungal DyP. Interestingly, Pleos-DyP4 (together with ligninolytic peroxidases) is detected in the secretome of P. ostreatus grown on different lignocellulosic substrates. In conclusion, it is suggested that generation of Mn3+ oxidizers plays a role in the P. ostreatus white-rot lifestyle since three different families of Mn2+-oxidizing peroxidase genes are present in its genome being expressed during lignocellulose degradation.

  10. Controlling the structure of manganese(II) phosphates by the choice and ratio of organophosphate and auxiliary ligands.

    PubMed

    Murugavel, Ramaswamy; Kuppuswamy, Subramaniam; Gogoi, Nayanmoni; Steiner, Alexander; Bacsa, John; Boomishankar, Ramamoorthy; Suresh, K G

    2009-01-05

    Tetranuclear manganese(II) phosphates [Mn(dipp)(bpy)](4)4 H(2)O (1) and [Mn(4)(dmpp)(2)(dmppH)(4)(bpy)(4)(H(2)O)(2)]H(2)O (2) have been prepared from Mn(OAc)(2)4 H(2)O and 2,6-diisopropylphenyl phosphate (dippH(2)) or 2,6-dimethylphenyl phosphate (dmppH(2)) in the presence of 2,2'-bipyridine (bpy). In contrast, the reaction between [Mn(bpy)(2)(OAc)(ClO(4))]H(2)O and dippH(2) affords [Mn(bpy)(2)(dippH)](2)2 ClO(4)2 CH(3)OH (3). The reactions of Mn(OAc)(2)4 H(2)O, dippH(2), and pyridine (py) or 3,5-dimethylpyrazole (dmpz) in CH(3)CN under reflux afford hexanuclear complexes [Mn(6)(dipp)(6)(py)(8)]2CH(3)CN (4) and [Mn(6)(dipp)(6)(dmpz)(6)(AcOH)(2)]2 H(2)O (5), respectively. Although compounds 1 and 2 are tetrameric, the former is a closed cubane-like structure resembling the D4R secondary building unit of zeolites, whereas the latter exists in a staircase structure with fused Mn(2)O(4)P(2) rings. The core structure of 3 contains a Mn(2)O(4)P(2) eight-membered ring that resembles the S4R building block of zeolites. Single-crystal X-ray diffraction studies reveal that compounds 4 and 5 have a similar core structure and differ from each other by the neutral ligands coordinated to manganese ions. All six phosphate ligands exist in a doubly deprotonated [(RO)PO(3) (2-)] form and exhibit two types of binding modes [5.222] and [3.111]. An interesting feature of compounds 1-5 is that although they are oligonuclear complexes, there is an absence of oxido bridges. The magnetic properties of compounds 1-5 have been investigated in the temperature range 5-298 K, and it was found that all the compounds obey the Curie law.

  11. Hypoxia-induced exposure of isaza fish to manganese and arsenic at the bottom of Lake Biwa, Japan: experimental and geochemical verification.

    PubMed

    Itai, Takaaki; Hayase, Daisuke; Hyobu, Yuika; Hirata, Sawako H; Kumagai, Michio; Tanabe, Shinsuke

    2012-06-05

    In December 2007, a mass mortality of isaza (Gymnogobius isaza), a goby fish in Lake Biwa, Japan, was observed under severe hypoxia. Considering the level of manganese and arsenic in the dead isaza during the event was much higher than that in live isaza, hypoxia-induced mobilization of manganese and arsenic and subsequent exposure could be the reason for this adverse effect. However, secondary accumulation of manganese and arsenic after the mortality event could not be ruled out. To test this hypothesis, we conducted tissue distribution/speciation analysis and absorption tests on dead specimens. All the results, particularly the limited absorption of arsenic in the absorption tests, indicated that the isaza were exposed to arsenic before the mortality event. Parallel to this, the geochemical behavior of manganese and arsenic in oxygen-rich conditions (June) and oxygen-poor conditions (December) was investigated to verify the mechanism of exposure. Considerable enrichment of manganese and arsenic in a thin surface layer of sediment was a common feature in all seven stations studied. In the water at the bottom of the lake, a clear increase of arsenite in December was observed, and the manganese level was several hundred times higher in both seasons than the average level of the lake. Although further verification is needed, the data provided here support exposure to manganese and arsenic under hypoxia.

  12. Synthesis, spectral elucidation, electrochemistry and DFT interpretation of manganese(II)-thioalkyl-arylazoimidazole complex

    NASA Astrophysics Data System (ADS)

    Nandi, Soumendranath; Das, Kuheli; Datta, Amitabha; Banerjee, Debashis; Roy, Suman; Mondal, Tapan Kumar; Mandal, Debashree; Nanda, Prasanta Kumar; Akitsu, Takashiro; Tanaka, Shinnosuke; Sinha, Chittaranjan

    2017-04-01

    One new Mn(II) thioalkyl-arylazoimidazole complex (1), [Mn(SRaaiNR/)2(SCN)2] (SRaaiNR/ = 1-alkyl-2-{(o-thioalkyl)phenylazo}imidazole and R = Me, R/ = Et) is afforded and systematically characterized by FT-IR, UV-Vis and EPR spectroscopy. The single crystal X-ray diffraction technique reveals that in complex 1, the central Mn atom possesses a tetrahedral environment of MnN4 sphere; coordinated by a pair of monodentate orientation of Nimidazolyl and NSCN atoms. Variable temperature magnetic moment confirms that in complex 1, there exists an antiferromagnetic coupling in tetrahedral symmetry. Cyclic voltammogram study of complex 1 evidenced the presence of a Mn(III)/Mn(II) redox response at 1.25 V alongwith azo reductions at -0.8 V. DFT computational using optimized geometry clearly explains the electronic and redox properties which is in accordance with the experimental evidence.

  13. Honeycomb-like S = 5/2 Spin–Lattices in Manganese(II) Vanadates

    DOE PAGES

    Sanjeewa, Liurukara. D.; McGuire, Michael A.; McMillen, Colin D.; ...

    2016-08-26

    We synthesized new complex manganese vanadate materials as high-quality single crystals in multi-millimeter lengths using a high-temperature, high-pressure hydrothermal method. We grew one compound, Mn5(VO4)2(OH)4, from Mn2O3 and V2O5 in 3 M CsOH at 580 °C and 1.5 kbar. Changing the mineralizer to 1 M CsOH/3MCsCl leads to the formation of another product, Mn6O(VO4)2(OH). Both compounds were structurally characterized by single-crystal X-ray diffraction (Mn5(VO4)2(OH)4: C2/m, Z = 2, a = 9.6568(9) Å, b = 9.5627(9) Å, c = 5.4139(6) Å, β = 98.529(8)°; Mn6O(VO4)2(OH): P21/m, Z = 2, a = 8.9363(12) Å, b = 6.4678(8) Å, c = 10.4478(13) Å,more » β = 99.798(3)°), revealing interesting low-dimensional transition-metal features. Mn5(VO4)2(OH)4 possesses complex honeycomb-type Mn–O layers, built from edge-sharing [MnO6] octahedra in the bc plane, with bridging vanadate groups connecting these layers along the a-axis. Mn6O(VO4)2(OH) presents a more complicated structure with both octahedral [MnO6] and trigonal bipyramidal [MnO5] units. A different pattern of planar honeycomb sheets are formed by edge-shared [MnO6] octahedra, and these sublattices are connected through edge-shared dimers of [MnO5] trigonal bipyramids to form corrugated sheets. Vanadate groups again condense the sheets into a three-dimensional framework. Infrared and Raman spectroscopies indicated the presence of OH groups and displayed characteristic Raman scattering due to vanadate groups. Furthermore, temperature-dependent magnetic studies indicated Curie–Weiss behavior above 100 K with significant anti-ferromagnetic coupling for both compounds, with further complex magnetic behavior at lower temperatures. The data indicate canted anti-ferromagnetic order below 57 K in Mn5(VO4)2(OH)4 and below 45 K in Mn6O(VO4)2(OH). Members of another class of compounds, K2M3(VO4)2(OH)2 (M = Mn, Co), also containing a honeycomb-type sublattice, were also synthesized to allow a comparison of the structural

  14. Honeycomb-like S = 5/2 Spin–Lattices in Manganese(II) Vanadates

    SciTech Connect

    Sanjeewa, Liurukara. D.; McGuire, Michael A.; McMillen, Colin D.; Willett, Daniel; Chumanov, George; Kolis, Joseph W.

    2016-08-26

    We synthesized new complex manganese vanadate materials as high-quality single crystals in multi-millimeter lengths using a high-temperature, high-pressure hydrothermal method. We grew one compound, Mn5(VO4)2(OH)4, from Mn2O3 and V2O5 in 3 M CsOH at 580 °C and 1.5 kbar. Changing the mineralizer to 1 M CsOH/3MCsCl leads to the formation of another product, Mn6O(VO4)2(OH). Both compounds were structurally characterized by single-crystal X-ray diffraction (Mn5(VO4)2(OH)4: C2/m, Z = 2, a = 9.6568(9) Å, b = 9.5627(9) Å, c = 5.4139(6) Å, β = 98.529(8)°; Mn6O(VO4)2(OH): P21/m, Z = 2, a = 8.9363(12) Å, b = 6.4678(8) Å, c = 10.4478(13) Å, β = 99.798(3)°), revealing interesting low-dimensional transition-metal features. Mn5(VO4)2(OH)4 possesses complex honeycomb-type Mn–O layers, built from edge-sharing [MnO6] octahedra in the bc plane, with bridging vanadate groups connecting these layers along the a-axis. Mn6O(VO4)2(OH) presents a more complicated structure with both octahedral [MnO6] and trigonal bipyramidal [MnO5] units. A different pattern of planar honeycomb sheets are formed by edge-shared [MnO6] octahedra, and these sublattices are connected through edge-shared dimers of [MnO5] trigonal bipyramids to form corrugated sheets. Vanadate groups again condense the sheets into a three-dimensional framework. Infrared and Raman spectroscopies indicated the presence of OH groups and displayed characteristic Raman scattering due to vanadate groups. Furthermore, temperature-dependent magnetic studies indicated Curie–Weiss behavior above 100 K with significant anti-ferromagnetic coupling for both compounds, with further complex magnetic behavior at

  15. Manganese pre-treatment attenuates cadmium induced hepatotoxicity in Swiss albino mice.

    PubMed

    Chaudhary, Shaista; Iram, Sidra; Raisuddin, Sheikh; Parvez, Suhel

    2015-01-01

    Cadmium (Cd) is a soft, malleable bluish-white metal with low melting point, a ubiquitous heavy metal and an environmental pollutant, found in soil, water and air. The presence of Cd in the components of the environment such as air, soil and groundwater is to a large part due to human activity, and the general population is exposed mainly by contaminated drinking water or food. Manganese (Mn) is a component in many enzymes, which play an important role in counteracting oxidative stress. In vitro experiments have revealed the ability of Mn to scavenge oxygen free radicals generated in differently mediated lipid peroxidation (LPO) conditions. The aim of the present study was to investigate the in vivo preventive effect of Mn(2+) pre-treatment on acute Cd-intoxication with regard to oxidative stress biomarker and antioxidant defense system in liver of Swiss albino mice. On exposure to Cd a significant increase in LPO levels, decrease in thiol content and induction in glutathione metabolizing enzyme were observed. Mn pre-treatment attenuated the modulation caused in the above-mentioned parameters due to acute Cd exposure in mice. In conclusion, the results from this study demonstrate that the protective effect of Mn in Cd-induced systemic toxicity in mice. Further investigations are required on the relation between Mn accumulation and resistance to oxidative stress and on the factors influencing Mn/Cd transport in rodents are needed to elucidate the molecular basis of this protective effect. Copyright © 2014 Elsevier GmbH. All rights reserved.

  16. Synthesis, crystal structure, spectroscopic characterization and nonlinear optical properties of manganese (II) complex of picolinate: A combined experimental and computational study

    NASA Astrophysics Data System (ADS)

    Tamer, Ömer; Avcı, Davut; Atalay, Yusuf; Çoşut, Bünyemin; Zorlu, Yunus; Erkovan, Mustafa; Yerli, Yusuf

    2016-02-01

    A novel manganese (II) complex with picolinic acid (pyridine 2-carboxylic acid, Hpic), namely, [Mn(pic)2(H2O)2] was prepared and its crystal structure was fully characterized by using single crystal X-ray diffraction. Picolinate (pic) ligands were coordinated to the central manganese(II) ion as bidentate N,O-donors through the nitrogen atoms of pyridine rings and the oxygen atoms of carboxylate groups forming five-membered chelate rings. The spectroscopic characterization of Mn(II) complex was performed by the applications of FT-IR, Raman, UV-vis and EPR techniques. In order to support these studies, density functional theory (DFT) calculations were carried out by using B3LYP level. IR and Raman spectra were simulated at B3LYP level, and obtained results indicated that DFT calculations generally give compatible results to the experimental ones. The electronic structure of the Mn(II) complex was predicted using time dependent DFT (TD-DFT) method with polarizable continuum model (PCM). Molecular stability, hyperconjugative interactions, intramolecular charge transfer (ICT) and bond strength were investigated by applying natural bond orbital (NBO) analysis. Nonlinear optical properties of Mn(II) complex were investigated by the determining of molecular polarizability (α) and hyperpolarizability (β) parameters.

  17. Synthesis, characterization, biological evaluation and docking studies of macrocyclic binuclear manganese(II) complexes containing 3,5-dinitrobenzoyl pendant arms.

    PubMed

    Arthi, P; Shobana, S; Srinivasan, P; Mitu, L; Kalilur Rahiman, A

    2015-05-15

    A series of bis(phenoxo) bridged binuclear manganese(II) complexes of the type [Mn2L(1-3)](ClO4)2 (1-3) containing 3,5-dinitrobenzoyl pendant-arms have been synthesized by cyclocondensation of 2,6-diformyl-4-R-phenols (where R=CH3, C(CH3)3 or Br) with 2,2'-3,5-dinitrobenzoyliminodi(ethylamine) trihydrochloride in the presence of manganese(II) perchlorate. The IR spectra of complexes indicate the presence of uncoordinated perchlorate anions. The UV-Vis spectra of complexes suggest the distorted octahedral geometry around manganese(II) nuclei. The EPR spectra of Mn(II) complexes show a broad signal with g value 2.03-2.04, which is characteristic for octahedral high spin Mn(2+) complex. The observed room temperature magnetic moment values of the Mn(II) complexes (5.60-5.62B.M.) are less than the normal value (5.92B.M.), indicating weak antiferromagnetic coupling interaction between the two metal ions. Electrochemical studies of the complexes show two distinct quasi-reversible one electron transfer processes in the cathodic (E(1)pc=-0.73 to -0.76V, E(2)pc=-1.30 to -1.36V), and anodic (E(1)pa=1.02-1.11V, E(2)pa=1.32-1.79V) potential regions. Antibacterial efficacy of complexes have been screened against four Gram (-ve) and two Gram (+ve) bacterial strains. The DNA interaction studies suggest that these complexes bind with CT-DNA by intercalation, giving the binding affinity in the order 1>2>3. All the complexes display significant cleavage activity against circular plasmid pBR322 DNA. Docking simulation was performed to insert complexes into the crystal structure of EGFR tyrosine kinase and B-DNA at active site to determine the probable binding mode.

  18. Cobalt and manganese diphosphonates with one-, two-, and three-dimensional structures and field-induced magnetic transitions.

    PubMed

    Cao, Deng-Ke; Liu, Mei-Juan; Huang, Jian; Bao, Song-Song; Zheng, Li-Min

    2011-03-21

    Reactions of 2-(1-Imidazole)-1-hydroxyl-1,1'-ethylidenediphosphonic acid (ImhedpH(4)) and cobalt or manganese salts under hydrothermal conditions result in three new metal diphosphonates: β-Co(3)(ImhedpH)(2)(H(2)O)(4)·2H(2)O (1), Co(3)(ImhedpH)(2)(H(2)O)(4) (2), and Mn(ImhedpH(2))·H(2)O (3). In compound 1, the columns made up of {Co1(2)O(2)} dimers and {PO(3)C} tetrahedra through corner-sharing are cross-linked through {Co2O(6)} octahedra, forming an inorganic layer. Neighboring layers are pillared by coordinated imidazole groups of ImhedpH(-) ligands, leading to a three-dimensional open framework containing two kinds of channels with sizes of 8.256 × 9.851 Å and 8.030 × 4.745 Å (van der Waals radii not accounted for). Compound 2 shows a layer structure, in which Co(3)(ImhedpH)(2)(H(2)O)(4) trimer units are connected through the corner-sharing of {Co1O(5)} trigonal bipyramids and {PO(3)C} tetrahedra, forming an inorganic layer containing 20-member rings composed of six Co atoms, two μ(3)-O1 units, and four O-P-O units. The noncoordinated imidazole groups protrude from two sides of the layer. Compound 3 shows a ladder structure, where the Mn(II) ions are bridged by ImhedpH(2)(2-) ligands through double O-P-O units to form a single chain, and two such chains are further fused together by sharing edges of {MnO(5)} trigonal bipyramids. The magnetic properties of 1-3 have been studied. Ferrimagnetism and field-induced magnetic transition from ferrimagnetism to a fully polarized state are observed in 1. Compounds 2 and 3 reveal dominant antiferromagnetic interactions between metal centers, and two-step field-induced magnetic phase transitions are found in 2.

  19. Induced gravity II: grand unification

    NASA Astrophysics Data System (ADS)

    Einhorn, Martin B.; Jones, D. R. Timothy

    2016-05-01

    As an illustration of a renormalizable, asymptotically-free model of induced gravity, we consider an SO(10) gauge theory interacting with a real scalar multiplet in the adjoint representation. We show that dimensional transmutation can occur, spontaneously breaking SO(10) to SU(5)⊗U(1), while inducing the Planck mass and a positive cosmological constant, all proportional to the same scale v. All mass ratios are functions of the values of coupling constants at that scale. Below this scale (at which the Big Bang may occur), the model takes the usual form of Einstein-Hilbert gravity in de Sitter space plus calculable corrections. We show that there exist regions of parameter space in which the breaking results in a local minimum of the effective action giving a positive dilaton (mass)2 from two-loop corrections associated with the conformal anomaly. Furthermore, unlike the singlet case we considered previously, some minima lie within the basin of attraction of the ultraviolet fixed point. Moreover, the asymptotic behavior of the coupling constants also lie within the range of convergence of the Euclidean path integral, so there is hope that there will be candidates for sensible vacua. Although open questions remain concerning unitarity of all such renormalizable models of gravity, it is not obvious that, in curved backgrounds such as those considered here, unitarity is violated. In any case, any violation that may remain will be suppressed by inverse powers of the reduced Planck mass.

  20. Hyperfine structure constants for singly ionized manganese (Mn II) using Fourier transform spectroscopy

    NASA Astrophysics Data System (ADS)

    Townley-Smith, Keeley; Nave, Gillian; Pickering, Juliet C.; Blackwell-Whitehead, Richard J.

    2016-09-01

    We expand on the comprehensive study of hyperfine structure (HFS) in Mn II conducted by Holt et al. (1999) by verifying hyperfine magnetic dipole constants (A) for 20 levels previously measured by Holt et al. (1999) and deriving A constants for 47 previously unstudied levels. The HFS patterns were measured in archival spectra from Fourier transform (FT) spectrometers at Imperial College London and the National Institute of Standards and Technology. Analysis of the FT spectra was carried out in XGREMLIN. Our A constant for the ground level has a lower uncertainty by a factor of 6 than that of Blackwell-Whitehead et al.

  1. Crystal structure of hexa-kis-(dimethyl sulfoxide-κO)manganese(II) diiodide.

    PubMed

    Glatz, Mathias; Schroffenegger, Martina; Weil, Matthias; Kirchner, Karl

    2016-07-01

    The asymmetric unit of the title salt, [Mn(C2H6OS)6]I2, consists of one Mn(II) ion, six O-bound dimethyl sulfoxide (DMSO) ligands and two I(-) counter-anions. The isolated complex cations have an octa-hedral configuration and are grouped in hexa-gonally arranged rows extending parallel to [100]. The two I(-) anions are located between the rows and are linked to the cations through two weak C-H⋯I inter-actions.

  2. Open-Framework Manganese(II) and Cobalt(II) Borophosphates with Helical Chains: Structures, Magnetic, and Luminescent Properties.

    PubMed

    Li, Min; Smetana, Volodymyr; Wilk-Kozubek, Magdalena; Mudryk, Yaroslav; Alammar, Tarek; Pecharsky, Vitalij K; Mudring, Anja-Verena

    2017-09-01

    Two borophosphates, (NH4)1-2xM1+x(H2O)2(BP2O8)·yH2O with M = Mn (I) and Co (II), synthesized hydrothermally crystallize in enantiomorphous space groups P6522 and P6122 with a = 9.6559(3) and 9.501(3) Å, c = 15.7939(6) and 15.582(4) Å, and V = 1275.3(1) and 1218.2(8) Å(3) for I and II, respectively. Both compounds feature helical chains composed of vertex-sharing tetrahedral PO4 and BO4 groups that are connected through O atoms to transition-metal cations, Mn(2+) and Co(2+), respectively. For the two crystallographically distinct transition-metal cation sites present in the structure, this results in octahedral coordination with different degrees of distortion from the ideal symmetry. The crystal-field parameters, calculated from the corresponding absorption spectra, indicate that Mn(2+) and Co(2+) ions are located in a weak octahedral-like crystal field and suggest that the Co-ligand interactions are more covalent than the Mn-ligand ones. Luminescence measurements at room temperature reveal an orange emission that red-shifts upon lowering of the temperature to 77 K for I, while II is not luminescent. The luminescence lifetimes of I are 33.4 μs at room temperature and 1.87 ms at 77 K. Both compounds are Curie-Weiss paramagnets with negative Weiss constants and effective magnetic moments expected for noninteracting Mn(2+) and Co(2+) cations but no clear long-range magnetic order above 2 K.

  3. The role of chemical speciation, chemical fractionation and calcium disruption in manganese-induced developmental toxicity in zebrafish (Danio rerio) embryos.

    PubMed

    Hernández, R B; Nishita, M I; Espósito, B P; Scholz, S; Michalke, B

    2015-10-01

    Manganese (Mn) is an essential nutrient that can be toxic in excess concentrations, especially during early development stages. The mechanisms of Mn toxicity is still unclear, and little information is available regarding the role of Mn speciation and fractionation in toxicology. We aimed to investigate the toxic effects of several chemical forms of Mn in embryos of Danio rerio exposed during different development stages, between 2 and 122h post fertilization. We found a stage-specific increase of lethality associated with hatching and removal of the chorion. Mn(II), ([Mn(H2O)6](2+)) appeared to be the most toxic species to embryos exposed for 48h, and Mn(II) citrate was most toxic to embryos exposed for 72 and/or 120h. Manganese toxicity was associated with calcium disruption, manganese speciation and metal fractionation, including bioaccumulation in tissue, granule fractions, organelles and denaturated proteins.

  4. Update on a Pharmacokinetic-Centric Alternative Tier II Program for MMT—Part II: Physiologically Based Pharmacokinetic Modeling and Manganese Risk Assessment

    PubMed Central

    Taylor, Michael D.; Clewell, Harvey J.; Andersen, Melvin E.; Schroeter, Jeffry D.; Yoon, Miyoung; Keene, Athena M.; Dorman, David C.

    2012-01-01

    Recently, a variety of physiologically based pharmacokinetic (PBPK) models have been developed for the essential element manganese. This paper reviews the development of PBPK models (e.g., adult, pregnant, lactating, and neonatal rats, nonhuman primates, and adult, pregnant, lactating, and neonatal humans) and relevant risk assessment applications. Each PBPK model incorporates critical features including dose-dependent saturable tissue capacities and asymmetrical diffusional flux of manganese into brain and other tissues. Varied influx and efflux diffusion rate and binding constants for different brain regions account for the differential increases in regional brain manganese concentrations observed experimentally. We also present novel PBPK simulations to predict manganese tissue concentrations in fetal, neonatal, pregnant, or aged individuals, as well as individuals with liver disease or chronic manganese inhalation. The results of these simulations could help guide risk assessors in the application of uncertainty factors as they establish exposure guidelines for the general public or workers. PMID:22645610

  5. Update on a Pharmacokinetic-Centric Alternative Tier II Program for MMT-Part II: Physiologically Based Pharmacokinetic Modeling and Manganese Risk Assessment.

    PubMed

    Taylor, Michael D; Clewell, Harvey J; Andersen, Melvin E; Schroeter, Jeffry D; Yoon, Miyoung; Keene, Athena M; Dorman, David C

    2012-01-01

    Recently, a variety of physiologically based pharmacokinetic (PBPK) models have been developed for the essential element manganese. This paper reviews the development of PBPK models (e.g., adult, pregnant, lactating, and neonatal rats, nonhuman primates, and adult, pregnant, lactating, and neonatal humans) and relevant risk assessment applications. Each PBPK model incorporates critical features including dose-dependent saturable tissue capacities and asymmetrical diffusional flux of manganese into brain and other tissues. Varied influx and efflux diffusion rate and binding constants for different brain regions account for the differential increases in regional brain manganese concentrations observed experimentally. We also present novel PBPK simulations to predict manganese tissue concentrations in fetal, neonatal, pregnant, or aged individuals, as well as individuals with liver disease or chronic manganese inhalation. The results of these simulations could help guide risk assessors in the application of uncertainty factors as they establish exposure guidelines for the general public or workers.

  6. Manganese-enhanced magnetic resonance imaging reveals increased DOI-induced brain activity in a mouse model of schizophrenia

    PubMed Central

    Malkova, Natalia V.; Gallagher, Joseph J.; Yu, Collin Z.; Jacobs, Russell E.; Patterson, Paul H.

    2014-01-01

    Maternal infection during pregnancy increases the risk for schizophrenia in offspring. In rodent models, maternal immune activation (MIA) yields offspring with schizophrenia-like behaviors. None of these behaviors are, however, specific to schizophrenia. The presence of hallucinations is a key diagnostic symptom of schizophrenia. In mice, this symptom can be defined as brain activation in the absence of external stimuli, which can be mimicked by administration of hallucinogens. We find that, compared with controls, adult MIA offspring display an increased stereotypical behavioral response to the hallucinogen 2,5-dimethoxy-4-iodoamphetamine (DOI), an agonist for serotonin receptor 2A (5-HT2AR). This may be explained by increased levels of 5-HT2AR and downstream signaling molecules in unstimulated MIA prefrontal cortex (PFC). Using manganese-enhanced magnetic resonance imaging to identify neuronal activation elicited by DOI administration, we find that, compared with controls, MIA offspring exhibit a greater manganese (Mn2+) accumulation in several brain areas, including the PFC, thalamus, and striatum. The parafascicular thalamic nucleus, which plays the role in the pathogenesis of hallucinations, is activated by DOI in MIA offspring only. Additionally, compared with controls, MIA offspring demonstrate higher DOI-induced expression of early growth response protein 1, cyclooxygenase-2, and brain-derived neurotrophic factor in the PFC. Chronic treatment with the 5-HT2AR antagonist ketanserin reduces DOI-induced head twitching in MIA offspring. Thus, the MIA mouse model can be successfully used to investigate activity induced by DOI in awake, behaving mice. Moreover, manganese-enhanced magnetic resonance imaging is a useful, noninvasive method for accurately measuring this type of activity. PMID:24889602

  7. Ammonia Binds to the Dangler Manganese of the Photosystem II Oxygen-Evolving Complex.

    PubMed

    Oyala, Paul H; Stich, Troy A; Debus, Richard J; Britt, R David

    2015-07-15

    High-resolution X-ray structures of photosystem II reveal several potential substrate binding sites at the water-oxidizing/oxygen-evolving 4MnCa cluster. Aspartate-61 of the D1 protein hydrogen bonds with one such water (W1), which is bound to the dangler Mn4A of the oxygen-evolving complex. Comparison of pulse EPR spectra of (14)NH3 and (15)NH3 bound to wild-type Synechocystis PSII and a D1-D61A mutant lacking this hydrogen-bonding interaction demonstrates that ammonia binds as a terminal NH3 at this dangler Mn4A site and not as a partially deprotonated bridge between two metal centers. The implications of this finding on identifying the binding sites of the substrate and the subsequent mechanism of dioxygen formation are discussed.

  8. Phosphatidylserine metabolism modification precedes manganese-induced apoptosis and phosphatidylserine exposure in PC12 cells.

    PubMed

    Ferrara, G; Gambelunghe, A; Mozzi, R; Marchetti, M C; Migliorati, G; Muzi, G; Buratta, S

    2013-12-01

    Long-term exposure to high manganese (Mn) levels can lead to Parkinson-like neurological disorders. Molecular mechanisms underlying Mn cytotoxicity have been not defined. It is known that Mn induces apoptosis in PC12 cells and that this involves the activation of some signal transduction pathways. Although the role of phospholipids in apoptosis and signal transduction is well-known, the membrane phospholipid component in Mn-related damage has not yet been investigated. Phosphatidylserine (PS) facilitates protein translocation from cytosol to plasma membrane and PS exposure on the cell surface allows macrophage recognition of apoptotic cells. This study investigates the effects of MnCl2 on PS metabolism in PC12 cells, relating them to those on cell apoptosis. Apoptosis induction decreased PS radioactivity of PC12 cells incubated with radioactive serine. MnCl2 reduced PS radioactivity even under conditions that did not affect cell viability or PS exposure, suggesting that the effects on PS metabolism may represent an early event in cell apoptosis. Thus the latter conditions that also induced a greater PS decarboxylation were utilized for further investigating on the effects on PS synthesis, by measuring the activity and expression of PS-synthesizing enzymes, in cell lysates and in total cellular membranes (TM). Compared with corresponding controls, enzyme activity of MnCl2-treated cells was lower in cell lysates and greater in TM. Evaluating the expression of two isoforms of PS-synthesizing enzyme (PSS), PSSII was increased both in cell lysate and TM, while PSSI was unchanged. MnCl2 addition to control cell lysate reduced enzyme activity. These results suggest Mn plays a dual role on PS synthesis. Once inside the cell, Mn inhibits the enzyme/s, thus accounting for reduced PS synthesis in lysates and intact cells. On the other hand, it increases PSSII expression in cell membranes. The possibility that this occurs to counteract the direct effects of Mn ions on enzyme

  9. Structure of a new three-dimensional metal-organic framework: Poly[manganese(II)-bis-(µ4-1,4-naphthalenedicarboxylate)-bis-( N, N-dimethylformamide)

    NASA Astrophysics Data System (ADS)

    Wang, Q.; Yan, T.; Du, L.

    2015-11-01

    A novel metal-organic framework, [Mn2(C12H6O4)2(C3H7NO)2] n has been synthesized solvothermally by assembling ligands 1,4-naphthalenedicarboxylic acid (NDC), N, N-dimethylformamide (DMF) and manganese(II). Both independent Mn(II) ions are six-coordinated in a distorted octahedral environment with oxygen donors. Bis(bridging bidentate) μ4-η1:η1:η2:η1, NDC ligands orient in two directions, [010] and [001], linking the Mn(II) ions to form a square grid in (100) plane. Corner shared Mn(II) octahedral form chains along a direction resulting in a three dimensional network.

  10. Manganese(II) complexes with the non-steroidal anti-inflammatory drug tolfenamic acid: structure and biological perspectives.

    PubMed

    Zampakou, Marianthi; Rizeq, Natalia; Tangoulis, Vassilis; Papadopoulos, Athanasios N; Perdih, Franc; Turel, Iztok; Psomas, George

    2014-02-17

    Manganese(II) complexes with the non-steroidal anti-inflammatory drug tolfenamic acid (Htolf) with the nitrogen-donor heterocyclic ligands 1,10-phenanthroline (phen), pyridine (py), or 2,2'-bipyridylamine (bipyam) and/or the oxygen-donor ligands H2O or N,N-dimethylformamide (DMF) have been synthesized and characterized. The crystal structures of complexes [Mn(tolf-O)(tolf-O,O')(phen)(H2O)], [Mn2(μ2-tolf-O,O')2(tolf-O,O')2(bipyam)2], [Mn2(μ2-H2O)(μ2-tolf-O,O')2(tolf-O)2(py)4]·1.5MeOH·py, and [Mn(μ2-tolf-O,O')2(DMF)2]n have been determined by X-ray crystallography. The interaction of the complexes with serum albumin proteins was investigated, and relative high binding constant values were calculated. The ability of the compounds to scavenge 1,1-diphenyl-picrylhydrazyl, 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid), and hydroxyl radicals was evaluated, and [Mn(tolf)2(phen)(H2O)] was the most active scavenger among the compounds. The compounds have also exhibited noteworthy in vitro inhibitory activity against soybean lipoxygenase. UV titration studies of the interaction of the complexes with calf-thymus (CT) DNA have proved the binding to CT DNA with [Mn(μ2-tolf)2(DMF)2]n exhibiting the highest DNA-binding constant (Kb = 5.21 (±0.35) × 10(5) M(-1)). The complexes bind to CT DNA probably via intercalation as suggested by DNA-viscosity measurements and competitive studies with ethidium bromide (EB), which revealed the ability of the complexes to displace the DNA-bound EB.

  11. Molecular structure and spectroscopic properties of novel manganese(II) complex with sulfamethazine drug

    NASA Astrophysics Data System (ADS)

    Mansour, Ahmed M.

    2013-03-01

    [MnLCl(H2O)3]·H2O complex (HL = 4-amino-N-(4,6-dimethyl-2-pyrimidinyl)benzenesulfonamide, sulfamethazine) has been synthesized and characterized by elemental analysis, TG/DTA, MS, FT-IR, UV-Vis, magnetic, electrochemical, and X-ray powder diffraction. The experimental studies were complemented by quantum chemical calculations at DFT/B3LYP level of theory. Sulfamethazine behaves as a mono-negatively bidentate ligand and interacts with Mn(II) ion through sulfonamidic (N15) and pyrimidic (N23) nitrogen atoms. Electronic structures were investigated using TD-DFT method and the descriptions of frontier molecular orbitals and the relocation of the electron density were determined. The voltammogram of NaL shows one irreversible one-electron process due to oxidation of p-amino group, and one anodic peak characteristic of reduction of sbnd SO2 group. The synthesized complex, in comparison to the parent drug, was screened for its antibacterial activity.

  12. Comparative Analysis of Secretome Profiles of Manganese(II)-Oxidizing Ascomycete Fungi

    PubMed Central

    Zeiner, Carolyn A.; Purvine, Samuel O.; Zink, Erika M.; Paša-Tolić, Ljiljana; Chaput, Dominique L.; Haridas, Sajeet; Wu, Si; LaButti, Kurt; Grigoriev, Igor V.; Henrissat, Bernard; Santelli, Cara M.; Hansel, Colleen M.

    2016-01-01

    Fungal secretomes contain a wide range of hydrolytic and oxidative enzymes, including cellulases, hemicellulases, pectinases, and lignin-degrading accessory enzymes, that synergistically drive litter decomposition in the environment. While secretome studies of model organisms such as Phanerochaete chrysosporium and Aspergillus species have greatly expanded our knowledge of these enzymes, few have extended secretome characterization to environmental isolates or conducted side-by-side comparisons of diverse species. Thus, the mechanisms of carbon degradation by many ubiquitous soil fungi remain poorly understood. Here we use a combination of LC-MS/MS, genomic, and bioinformatic analyses to characterize and compare the protein composition of the secretomes of four recently isolated, cosmopolitan, Mn(II)-oxidizing Ascomycetes (Alternaria alternata SRC1lrK2f, Stagonospora sp. SRC1lsM3a, Pyrenochaeta sp. DS3sAY3a, and Paraconiothyrium sporulosum AP3s5-JAC2a). We demonstrate that the organisms produce a rich yet functionally similar suite of extracellular enzymes, with species-specific differences in secretome composition arising from unique amino acid sequences rather than overall protein function. Furthermore, we identify not only a wide range of carbohydrate-active enzymes that can directly oxidize recalcitrant carbon, but also an impressive suite of redox-active accessory enzymes that suggests a role for Fenton-based hydroxyl radical formation in indirect, non-specific lignocellulose attack. Our findings highlight the diverse oxidative capacity of these environmental isolates and enhance our understanding of the role of filamentous Ascomycetes in carbon turnover in the environment. PMID:27434633

  13. Comparative Analysis of Secretome Profiles of Manganese(II)-Oxidizing Ascomycete Fungi

    SciTech Connect

    Zeiner, Carolyn A.; Purvine, Samuel O.; Zink, Erika M.; Paša-Tolić, Ljiljana; Chaput, Dominique L.; Haridas, Sajeet; Wu, Si; LaButti, Kurt; Grigoriev, Igor V.; Henrissat, Bernard; Santelli, Cara M.; Hansel, Colleen M.; Pöggeler, Stefanie

    2016-07-19

    Fungal secretomes contain a wide range of hydrolytic and oxidative enzymes, including cellulases, hemicellulases, pectinases, and lignin-degrading accessory enzymes, that synergistically drive litter decomposition in the environment. While secretome studies of model organisms such as Phanerochaete chrysosporium and Aspergillus species have greatly expanded our knowledge of these enzymes, few have extended secretome characterization to environmental isolates or conducted side-by-side comparisons of diverse species. Thus, the mechanisms of carbon degradation by many ubiquitous soil fungi remain poorly understood. Here we use a combination of LC-MS/MS, genomic, and bioinformatic analyses to characterize and compare the protein composition of the secretomes of four recently isolated, cosmopolitan, Mn(II)-oxidizing Ascomycetes (Alternaria alternata SRC1lrK2f, Stagonospora sp. SRC1lsM3a, Pyrenochaeta sp. DS3sAY3a, and Paraconiothyrium sporulosum AP3s5-JAC2a). We demonstrate that the organisms produce a rich yet functionally similar suite of extracellular enzymes, with species-specific differences in secretome composition arising from unique amino acid sequences rather than overall protein function. Furthermore, we identify not only a wide range of carbohydrate-active enzymes that can directly oxidize recalcitrant carbon, but also an impressive suite of redox-active accessory enzymes that suggests a role for Fenton-based hydroxyl radical formation in indirect, non-specific lignocellulose attack. Our findings highlight the diverse oxidative capacity of these environmental isolates and enhance our understanding of the role of filamentous Ascomycetes in carbon turnover in the environment.

  14. Cocaine-induced locomotor sensitization in rats correlates with nucleus accumbens activity on manganese-enhanced MRI.

    PubMed

    Perrine, Shane A; Ghoddoussi, Farhad; Desai, Kirtan; Kohler, Robert J; Eapen, Ajay T; Lisieski, Michael J; Angoa-Perez, Mariana; Kuhn, Donald M; Bosse, Kelly E; Conti, Alana C; Bissig, David; Berkowitz, Bruce A

    2015-11-01

    A long-standing goal of substance abuse research has been to link drug-induced behavioral outcomes with the activity of specific brain regions to understand the neurobiology of addiction behaviors and to search for drug-able targets. Here, we tested the hypothesis that cocaine produces locomotor (behavioral) sensitization that correlates with increased calcium channel-mediated neuroactivity in brain regions linked with drug addiction, such as the nucleus accumbens (NAC), anterior striatum (AST) and hippocampus, as measured using manganese-enhanced MRI (MEMRI). Rats were treated with cocaine for 5 days, followed by a 2-day drug-free period. The following day, locomotor sensitization was quantified as a metric of cocaine-induced neuroplasticity in the presence of manganese. Immediately following behavioral testing, rats were examined for changes in calcium channel-mediated neuronal activity in the NAC, AST, hippocampus and temporalis muscle, which was associated with behavioral sensitization using MEMRI. Cocaine significantly increased locomotor activity and produced behavioral sensitization compared with saline treatment of control rats. A significant increase in MEMRI signal intensity was determined in the NAC, but not AST or hippocampus, of cocaine-treated rats compared with saline-treated control rats. Cocaine did not increase signal intensity in the temporalis muscle. Notably, in support of our hypothesis, behavior was significantly and positively correlated with MEMRI signal intensity in the NAC. As neuronal uptake of manganese is regulated by calcium channels, these results indicate that MEMRI is a powerful research tool to study neuronal activity in freely behaving animals and to guide new calcium channel-based therapies for the treatment of cocaine abuse and dependence.

  15. Anti-oxidant, in vitro, in vivo anti-inflammatory activity and antiproliferative activity of mefenamic acid and its metal complexes with manganese(II), cobalt(II), nickel(II), copper(II) and zinc(II).

    PubMed

    Kovala-Demertzi, Dimitra; Hadjipavlou-Litina, Dimitra; Staninska, Malgorzata; Primikiri, Alexandra; Kotoglou, Chronis; Demertzis, Mavroudis A

    2009-06-01

    Some new complexes of mefenamic acid with potentially interesting biological activity are described. The complexes of mefenamic acid [Mn(mef)(2)(H(2)O)(2)], 1, [Co(mef)(2)(H(2)O)(2)], 2, [Ni(mef)(2)(H(2)O)(2)], 3, [Cu(mef)(2)(H(2)O)](2), 4 and [Zn(mef)(2)], 5, were prepared by the reaction of mefenamic acid, a potent anti-inflammatory drug with metal salts. Optical and infrared spectral data of these new complexes are reported. Monomeric six-coordinated species were isolated in the solid state for Mn(II), Ni(II) and Co(II), dimeric five-coordinated for Cu(II) and monomeric four-coordinated for Zn(II). In DMF or CHCl(3) solution the coordination number is retained and the coordinated molecules of water are replaced by solvent molecules. The anti-oxidant properties of the complexes were evaluated using the 1,1-diphenyl-2-picrylhydrazyl, DPPH, free radical scavenging assay. The scavenging activities of the complexes were measured and compared with those of the free drug and vitamin C. We have explored their ability to inhibit soybean lipoxygenase, beta-glucuronidase and trypsin- induced proteolysis. The complex [Mn(mef)(2)(H(2)O)(2)] exhibits the highest antioxidant activity and the highest inhibitory effect against the soybean lipogygenase (LOX), properties that are not demonstrated by mefenamic acid. Their inhibitory effects on rat paw edema induced by Carrageenan was studied and compared with those of mefenamic acid. The complex [Zn(mef)(2)] exhibited a strong inhibitory effect at 0.1 mmol/Kg B.W. (81.5 +/- 1.3% inhibition), superior to the inhibition induced by mefenamic acid at the same dose (61.5 +/- 2.3% inhibition). Mefenamic acid and its metal complexes have been evaluated for antiproliferative activity in vitro against the cells of three human cancer cell lines: MCF-7 (human breast cancer cell line), T24 (bladder cancer cell line), A-549 (non-small cell lung carcinoma) and a mouse fibroblast L-929 cell line. The copper(II) complex displays against T24, MCF-7

  16. In situ FT-IR and UV-vis spectroscopy of the low-temperature NO disproportionation mediated by solid state manganese(II) porphyrinates.

    PubMed

    Martirosyan, Garik G; Azizyan, Arsen S; Kurtikyan, Tigran S; Ford, Peter C

    2006-05-15

    The heterogeneous reaction between NO gas and sublimed layers of manganese(II) porphyrinato complexes Mn(Por) (Por = TPP (tetraphenylporphyrinato dianion), TMP (tetramesitylporphyrinato dianion), or TPP(d20) (perdeuterated tetraphenylporphyrinato dianion)) has been monitored by IR and optical spectroscopy over the temperature range of 77 K to room temperature. These manganese porphyrins promote NO disproportionation to NO2 species and N2O, and the reaction proceeds via several distinct stages. At 90 K, the principal species observed spectrally are the nitric oxide dimer, cis-ONNO, two manganese nitrosyls, the simple NO adduct Mn(Por)(NO), and another intermediate (1) that is apparently critical to the disproportionation mechanism. This key intermediate is formed prior to N2O evolution, and proposals regarding its likely structure are offered. When the system is warmed to 130 K, the disproportionation products, N2O and the O-coordinated nitrito complex Mn(Por)(NO)(ONO) (2), are formed. IR spectral changes show that, upon further warming to 200 K, 2 isomerizes into the N-bonded nitro linkage isomer Mn(Por)(NO)(NO2) (3). After it is warmed to room temperature, the latter species loses NO and converts to the known 5-coordinate nitrito complex Mn(Por)(ONO) (4).

  17. Mobilization of manganese by basalt associated Mn(II)-oxidizing bacteria from the Indian Ridge System.

    PubMed

    Sujith, P P; Mourya, B S; Krishnamurthi, S; Meena, R M; Loka Bharathi, P A

    2014-01-01

    The Indian Ridge System basalt bearing Mn-oxide coatings had todorokite as the major and birnesite as the minor mineral. We posit that microorganisms associated with these basalts participate in the oxidation of Mn and contribute to mineral deposition. We also hypothesized that, the Mn-oxidizing microbes may respond reversibly to pulses of fresh organic carbon introduced into the water column by mobilizing the Mn in Mn-oxides. To test these two hypotheses, we enumerated the number of Mn-oxidizers and -reducers and carried out studies on the mobilization of Mn by microbial communities associated with basalt. In medium containing 100 μM Mn(2+), 10(3) colony forming units (CFU) were recovered with undetectable number of reducers on Mn-oxide amended medium, suggesting that the community was more oxidative. Experiments were then conducted with basalt fragments at 4±2 °C in the presence 'G(+)' and absence 'G(-)' of glucose (0.1%). Controls included set-ups, some of which were poisoned with 15 mM azide and the others of which were heat-killed. The mobilization of Mn in the presence of glucose was 1.76 μg g(-1) d(-1) and in the absence, it was 0.17 μg g(-1) d(-1) after 150 d. Mn mobilization with and without added glucose was 13 and 4 times greater than the corresponding azide treated controls. However, rates in 'G(+)' were 16 times and 'G(-)' 24 times more than the respective heat killed controls. The corresponding total counts in the presence of added glucose increased from 1.63×10(6) to 6.71×10(7) cells g(-1) and from 1.41×10(7) to 3.52×10(7) cells g(-1) in its absence. Thus, the addition of glucose as a proxy for organic carbon changed the community's response from Mn(II)-oxidizing to Mn(IV)-reducing activity. The results confirm the participation of Mn oxidizing bacteria in the mobilization of Mn. Identification of culturable bacteria by 16S rRNA gene analysis showed taxonomic affiliations to Bacillus, Exiguobacterium, Staphylococcus, Brevibacterium and

  18. Cefepime, a fourth-generation cephalosporin, in complex with manganese, inhibits proteasome activity and induces the apoptosis of human breast cancer cells.

    PubMed

    Zhang, Zhen; Bi, Caifeng; Fan, Yuhua; Wang, Huannan; Bao, Yan

    2015-10-01

    Cefepime (FEP), which is a member of the fourth-generation cephalosporin class, has been extensively studied as a biochemical and antimicrobial reagent in recent years. Manganese (Mn) is important in the biochemical and physiological processes of many living organisms, and it is also high expressed in some tumor tissues. In the present study, we aimed to investigate the proteasome-inhibitory and anti-proliferative properties of 8 metal complexes (FEP‑Cu, FEP-Zn, FEP-Co, FEP-Ni, FEP-Cd, FEP-Cr, FEP-Fe, FEP-Mn) in MDA-MB‑231 human breast cancer cells. The FEP-Mn complex was found to be more potent in its ability to inhibit cell proliferation and proteasome activity than the other compounds tested. Moreover, the FEP-Mn complex inhibited proteasomal chymotrypsin-like (CT-like) activity and induced the apoptosis of breast cancer cells in a dose-and time-dependent manner. Furthermore, the MCF-10A cells were much less sensitive to the FEP complexes compared with the MDA-MB-231 breast cancer cells. These results demonstrated that the FEP-Mn(II) complex has the potential to act as a proteasome inhibitor and apoptosis inducer and therefore has possible future applications in cancer chemotherapy.

  19. The effect of induced anoxia and reoxygenation on benthic fluxes of organic carbon, phosphate, iron, and manganese.

    PubMed

    Skoog, Annelie C; Arias-Esquivel, Victor A

    2009-11-15

    Eutrophication causes seasonally anoxic bottom waters in coastal environments, but we lack information on effects of onset of anoxia and subsequent reoxygenation on benthic fluxes of redox-sensitive minerals and associated organic carbon (OC). As the first study, we determined the effect of inducing anoxia and subsequently restoring oxic conditions in mesocosms with surface sediment and water from a coastal environment. These concentration changes were compared with those in an oxygenated control. We determined water column concentrations of dissolved organic carbon (DOC), particulate organic carbon (POC), iron, manganese, and phosphate. Benthic fluxes of DOC, POC, and iron increased at the onset of anoxia in oxygen-depleted treatments. DOC and iron concentrations increased concomitantly towards maxima, which may have indicated reductive dissolution of FeOOH and release of associated OC. The subsequent concomitant concentration decreases may have been the result of coprecipitation of OC with iron-containing minerals. In contrast, the phosphate-concentration increase occurred several days after the onset of anoxia and the manganese concentration was not affected by the onset of anoxia. Restoring oxic conditions resulted in a decrease in DOC, POC, and phosphate concentrations, which may indicate coprecipitation of OC with phosphate-containing minerals. The high DOC fluxes at the onset of anoxia indicate that redox oscillations may be important in OC degradation. Further, our results indicate a close coupling between OC cycling and dissolution/precipitation of iron-containing minerals in intermittently anoxic sediments.

  20. Template synthesis and spectral studies on mononuclear complexes of chromium(III) and manganese(II) with tetradentate N4 donor macrocycles

    NASA Astrophysics Data System (ADS)

    Kumar, Raj; Masih, Iffat; Fahmi, Nighat

    2013-01-01

    The present article deals with the synthesis, spectral characterization and antimicrobial activity of a series of new complexes of chromium(III) and manganese(II) of general formula [Cr(Macn)Cl2]·Cl and [Mn(Macn)Cl2] respectively. These complexes were prepared via template reaction by mixing methanolic solution of diacetyldihydrazone, diacids (oxalic acid, succinic acid, glutaric acid and adipic acid) with CrCl3·6H2O and MnCl2·4H2O in 2:2:1 M ratios respectively. The newly synthesized complexes were characterized on the basis of chemical analysis and spectral studies like IR, UV, ESR and X-ray diffraction. An octahedral structure has been proposed for the chromium(III) and manganese(II) macrocyclic complexes. The synthesized complexes were further tested in vitro against fungi and bacteria in order to assess their antibacterial and antifungal activities. The studies demonstrate that the complexes possess antimicrobial properties.

  1. Synthesis and characterization of iron(III), manganese(II), cobalt(II), nickel(II), copper(II) and zinc(II) complexes of salicylidene-N-anilinoacetohydrazone (H2L1) and 2-hydroxy-1-naphthylidene-N-anilinoacetohydrazone (H2L2).

    PubMed

    AbouEl-Enein, S A; El-Saied, F A; Kasher, T I; El-Wardany, A H

    2007-07-01

    Salicylidene-N-anilinoacetohydrazone (H(2)L(1)) and 2-hydroxy-1-naphthylidene-N-anilinoacetohydrazone (H(2)L(2)) and their iron(III), manganese(II), cobalt(II), nickel(II), copper(II) and zinc(II) complexes have been synthesized and characterized by IR, electronic spectra, molar conductivities, magnetic susceptibilities and ESR. Mononuclear complexes are formed with molar ratios of 1:1, 1:2 and 1:3 (M:L). The IR studies reveal various modes of chelation. The electronic absorption spectra and magnetic susceptibility measurements show that the iron(III), nickel(II) and cobalt(II) complexes of H(2)L(1) have octahedral geometry. While the cobalt(II) complexes of H(2)L(2) were separated as tetrahedral structure. The copper(II) complexes have square planar stereochemistry. The ESR parameters of the copper(II) complexes at room temperature were calculated. The g values for copper(II) complexes proved that the Cu-O and Cu-N bonds are of high covalency.

  2. Synthesis, characterization, biological evaluation and docking studies of macrocyclic binuclear manganese(II) complexes containing 3,5-dinitrobenzoyl pendant arms

    NASA Astrophysics Data System (ADS)

    Arthi, P.; Shobana, S.; Srinivasan, P.; Mitu, L.; Kalilur Rahiman, A.

    2015-05-01

    A series of bis(phenoxo) bridged binuclear manganese(II) complexes of the type [Mn2L1-3](ClO4)2 (1-3) containing 3,5-dinitrobenzoyl pendant-arms have been synthesized by cyclocondensation of 2,6-diformyl-4-R-phenols (where R = sbnd CH3, sbnd C(CH3)3 or sbnd Br) with 2,2‧-3,5-dinitrobenzoyliminodi(ethylamine) trihydrochloride in the presence of manganese(II) perchlorate. The IR spectra of complexes indicate the presence of uncoordinated perchlorate anions. The UV-Vis spectra of complexes suggest the distorted octahedral geometry around manganese(II) nuclei. The EPR spectra of Mn(II) complexes show a broad signal with g value 2.03-2.04, which is characteristic for octahedral high spin Mn2+ complex. The observed room temperature magnetic moment values of the Mn(II) complexes (5.60-5.62 B.M.) are less than the normal value (5.92 B.M.), indicating weak antiferromagnetic coupling interaction between the two metal ions. Electrochemical studies of the complexes show two distinct quasi-reversible one electron transfer processes in the cathodic (E1pc = -0.73 to -0.76 V, E2pc = -1.30 to -1.36 V), and anodic (E1pa = 1.02-1.11 V, E2pa = 1.32-1.79 V) potential regions. Antibacterial efficacy of complexes have been screened against four Gram (-ve) and two Gram (+ve) bacterial strains. The DNA interaction studies suggest that these complexes bind with CT-DNA by intercalation, giving the binding affinity in the order 1 > 2 > 3. All the complexes display significant cleavage activity against circular plasmid pBR322 DNA. Docking simulation was performed to insert complexes into the crystal structure of EGFR tyrosine kinase and B-DNA at active site to determine the probable binding mode.

  3. Elimination of manganese(II,III) oxidation in Pseudomonas putida GB-1 by a double knockout of two putative multicopper oxidase genes.

    PubMed

    Geszvain, Kati; McCarthy, James K; Tebo, Bradley M

    2013-01-01

    Bacterial manganese(II) oxidation impacts the redox cycling of Mn, other elements, and compounds in the environment; therefore, it is important to understand the mechanisms of and enzymes responsible for Mn(II) oxidation. In several Mn(II)-oxidizing organisms, the identified Mn(II) oxidase belongs to either the multicopper oxidase (MCO) or the heme peroxidase family of proteins. However, the identity of the oxidase in Pseudomonas putida GB-1 has long remained unknown. To identify the P. putida GB-1 oxidase, we searched its genome and found several homologues of known or suspected Mn(II) oxidase-encoding genes (mnxG, mofA, moxA, and mopA). To narrow this list, we assumed that the Mn(II) oxidase gene would be conserved among Mn(II)-oxidizing pseudomonads but not in nonoxidizers and performed a genome comparison to 11 Pseudomonas species. We further assumed that the oxidase gene would be regulated by MnxR, a transcription factor required for Mn(II) oxidation. Two loci met all these criteria: PputGB1_2447, which encodes an MCO homologous to MnxG, and PputGB1_2665, which encodes an MCO with very low homology to MofA. In-frame deletions of each locus resulted in strains that retained some ability to oxidize Mn(II) or Mn(III); loss of oxidation was attained only upon deletion of both genes. These results suggest that PputGB1_2447 and PputGB1_2665 encode two MCOs that are independently capable of oxidizing both Mn(II) and Mn(III). The purpose of this redundancy is unclear; however, differences in oxidation phenotype for the single mutants suggest specialization in function for the two enzymes.

  4. catena-Poly[[[aqua-chlorido-manganese(II)]-bis-[μ-1,1'-(oxydi-p-phenyl-ene)di-1H-imidazole-κN:N

    PubMed

    Mu, Xiao-Long

    2011-01-15

    The title coordination polymer, {[MnCl(C(18)H(14)N(4)O)(2)(H(2)O)]Cl·C(3)H(7)NO·H(2)O}(n), obtained by the solvothermal reaction of BIDPE and manganese(II) salt in H(2)O/DMF (DMF is dimethyl-formamide), is composed of a chain of [Mn(2)(BIDPE)(2)] [BIDPE is 1,1'-(oxydi-p-phenyl-ene)di-1H-imidazole] metallocyclic rings that exhibit inversion symmetry. The coordination about the Mn(II) ions is distorted octahedral with a MnClN(4)O coordination set. In the crystal, the polymeric chains are linked by O-H⋯Cl hydrogen bonds, forming a two-dimensional network parallel to (100). A number of C-H⋯Cl and C-H⋯O inter-actions are also present.

  5. Electrochemically-induced reversible transition from the tunneled to layered polymorphs of manganese dioxide.

    PubMed

    Lee, Boeun; Yoon, Chong Seung; Lee, Hae Ri; Chung, Kyung Yoon; Cho, Byung Won; Oh, Si Hyoung

    2014-08-14

    Zn-ion batteries are emerging energy storage systems eligible for large-scale applications, such as electric vehicles. These batteries consist of totally environmentally-benign electrode materials and potentially manufactured very economically. Although Zn/α-MnO2 systems produce high energy densities of 225 Wh kg(-1), larger than those of conventional Mg-ion batteries, they show significant capacity fading during long-term cycling and suffer from poor performance at high current rates. To solve these problems, the concrete reaction mechanism between α-MnO2 and zinc ions that occur on the cathode must be elucidated. Here, we report the intercalation mechanism of zinc ions into α-MnO2 during discharge, which involves a reversible phase transition of MnO2 from tunneled to layered polymorphs by electrochemical reactions. This transition is initiated by the dissolution of manganese from α-MnO2 during discharge process to form layered Zn-birnessite. The original tunneled structure is recovered by the incorporation of manganese ions back into the layers of Zn-birnessite during charge process.

  6. Electrochemically-induced reversible transition from the tunneled to layered polymorphs of manganese dioxide

    PubMed Central

    Lee, Boeun; Yoon, Chong Seung; Lee, Hae Ri; Chung, Kyung Yoon; Cho, Byung Won; Oh, Si Hyoung

    2014-01-01

    Zn-ion batteries are emerging energy storage systems eligible for large-scale applications, such as electric vehicles. These batteries consist of totally environmentally-benign electrode materials and potentially manufactured very economically. Although Zn/α-MnO2 systems produce high energy densities of 225 Wh kg−1, larger than those of conventional Mg-ion batteries, they show significant capacity fading during long-term cycling and suffer from poor performance at high current rates. To solve these problems, the concrete reaction mechanism between α-MnO2 and zinc ions that occur on the cathode must be elucidated. Here, we report the intercalation mechanism of zinc ions into α-MnO2 during discharge, which involves a reversible phase transition of MnO2 from tunneled to layered polymorphs by electrochemical reactions. This transition is initiated by the dissolution of manganese from α-MnO2 during discharge process to form layered Zn-birnessite. The original tunneled structure is recovered by the incorporation of manganese ions back into the layers of Zn-birnessite during charge process. PMID:25317571

  7. [Increased manganese superoxide dismutase and cyclin B1 expression in carnosine-induced inhibition of glioblastoma cell proliferation].

    PubMed

    Rybakova, Yu S; Kalen, A L; Eckers, J C; Fedorova, T N; Goswami, P C; Sarsour, E H

    2015-01-01

    Carnosine is an endogenous dipeptide with antiproliferative properties. Here we show that carnosine selectively inhibits proliferation of human glioblastoma cells (U-118-MG) compared to breast (MB231) and oral (Cal27 and FaDu) cancer cells. Carnosine-induced inhibition of U-118-MG proliferation is associated with a significant: decrease in cellular reactive oxygen species levels, increase in manganese superoxide dismutase (MnSOD) and increase in cyclin B1 expression resulting in G2-block. We conclude that the antiproliferative property of carnosine is due to its ability to enhance MnSOD and cyclin B1 expression. These results will be of significance to the potential application of carnosine in brain cancer therapy.

  8. 3D homometallic carboxylate ferrimagnet constructed from a manganese(II) succinate carboxylate layer motif pillared by isonicotinate spacers.

    PubMed

    Zeng, Ming-Hua; Wu, Mei-Chun; Liang, Hong; Zhou, Yan-Ling; Chen, Xiao-Ming; Ng, Seik-Weng

    2007-09-03

    A manganese succinate having a layer structure in which the layers are pillared by the isonicotinate spacers in a 3D architecture exhibits long-range ferrimagnetic order below 5.0 K, with the ferrimagnetism arising, for topological reasons, from the nature of the carboxylate binding modes. The compound is the first structurally authenticated example of a 3D ferrimagnet, featuring a homometallic topological ferrimagnetic sheet among metal carboxylates.

  9. Regional distributions of manganese, iron, copper, and zinc in the brains of 6-hydroxydopamine-induced parkinsonian rats.

    PubMed

    Tarohda, Tohru; Ishida, Yasushi; Kawai, Keiichi; Yamamoto, Masayoshi; Amano, Ryohei

    2005-09-01

    Time courses of changes in manganese, iron, copper, and zinc concentrations were examined in regions of the brain of a 6-hydroxydopamine (6-OHDA)-induced rat model of Parkinson's disease using inductively coupled plasma mass spectrometry (ICP-MS). The concentrations were simultaneously determined in brain section at the level of the substantia nigra 1, 3, 7, 10, 14, and 21 days after the 6-OHDA treatment and compared with those of control rats. The distributions of these elements were obtained for 18 regions of the sagittal section (1-mm thick). The ICP-MS results indicated that Mn, Fe, Cu, and Zn levels of the 6-OHDA-induced parkinsonian brain were observed to increase in all regions that lay along the dopaminergic pathway. In the substantia nigra, the increase in Mn level occurred rapidly from 3 to 7 days and preceded those in the other elements, reaching a plateau in the 6-OHDA brain. Iron and Zn levels increased gradually until 7 days and then increased rapidly from 7 to 10 days. The increase in the copper level was slightly delayed. In other regions, such as the globus pallidus, putamen, and amygdala, the levels of Mn, Fe, Cu, and Zn increased with time after 6-OHDA treatment, although the time courses of their changes were region-specific. These findings contribute to our understanding of the roles of Mn and Fe in the induction of neurological symptoms and progressive loss of dopaminergic neurons in the development of Parkinson's disease. Manganese may hold the key to disturbing cellular Fe homeostasis and accelerating Fe levels, which play the most important role in the development of Parkinson's disease.

  10. Protective effects of ebselen (Ebs) and para-aminosalicylic acid (PAS) against manganese (Mn)-induced neurotoxicity

    SciTech Connect

    Marreilha dos Santos, A.P.; Lucas, Rui L.; Andrade, Vanda; Mateus, M. Luísa; Milatovic, Dejan; Aschner, Michael; Batoreu, M. Camila

    2012-02-01

    Chronic, excessive exposure to manganese (Mn) may induce neurotoxicity and cause an irreversible brain disease, referred to as manganism. Efficacious therapies for the treatment of Mn are lacking, mandating the development of new interventions. The purpose of the present study was to investigate the efficacy of ebselen (Ebs) and para-aminosalicylic acid (PAS) in attenuating the neurotoxic effects of Mn in an in vivo rat model. Exposure biomarkers, inflammatory and oxidative stress biomarkers, as well as behavioral parameters were evaluated. Co-treatment with Mn plus Ebs or Mn plus PAS caused a significant decrease in blood and brain Mn concentrations (compared to rats treated with Mn alone), concomitant with reduced brain E{sub 2} prostaglandin (PGE{sub 2}) and enhanced brain glutathione (GSH) levels, decreased serum prolactin (PRL) levels, and increased ambulation and rearing activities. Taken together, these results establish that both PAS and Ebs are efficacious in reducing Mn body burden, neuroinflammation, oxidative stress and locomotor activity impairments in a rat model of Mn-induced toxicity. -- Highlights: ► The manuscript is unique in its approach to the neurotoxicity of Mn. ► The manuscript incorporates molecular, cellular and functional (behavioral) analyses. ► Both PAS and Ebs are effective in restoring Mn behavioral function. ► Both PAS and Ebs are effective in reducing Mn-induced oxidative stress. ► Both PAS and Ebs led to a decrease in Mn-induced neuro-inflammation.

  11. Pivotal roles of p53 transcription-dependent and -independent pathways in manganese-induced mitochondrial dysfunction and neuronal apoptosis.

    PubMed

    Wan, Chunhua; Ma, Xa; Shi, Shangshi; Zhao, Jianya; Nie, Xiaoke; Han, Jingling; Xiao, Jing; Wang, Xiaoke; Jiang, Shengyang; Jiang, Junkang

    2014-12-15

    Chronic exposure to excessive manganese (Mn) has been known to lead to neuronal loss and a clinical syndrome resembling idiopathic Parkinson's disease (IPD). p53 plays an integral role in the development of various human diseases, including neurodegenerative disorders. However, the role of p53 in Mn-induced neuronal apoptosis and neurological deficits remains obscure. In the present study, we showed that p53 was critically involved in Mn-induced neuronal apoptosis in rat striatum through both transcription-dependent and -independent mechanisms. Western blot and immunohistochemistrical analyses revealed that p53 was remarkably upregulated in the striatum of rats following Mn exposure. Coincidentally, increased level of cleaved PARP, a hallmark of apoptosis, was observed. Furthermore, using nerve growth factor (NGF)-differentiated PC12 cells as a neuronal cell model, we showed that Mn exposure decreased cell viability and induced apparent apoptosis. Importantly, p53 was progressively upregulated, and accumulated in both the nucleus and the cytoplasm. The cytoplasmic p53 had a remarkable distribution in mitochondria, suggesting an involvement of p53 mitochondrial translocation in Mn-induced neuronal apoptosis. In addition, Mn-induced impairment of mitochondrial membrane potential (ΔΨm) could be partially rescued by pretreatment with inhibitors of p53 transcriptional activity and p53 mitochondrial translocation, Pifithrin-α (PFT-α) and Pifithrin-μ (PFT-μ), respectively. Moreover, blockage of p53 activities with PFT-α and PFT-μ significantly attenuated Mn-induced reactive oxidative stress (ROS) generation and mitochondrial H₂O₂ production. Finally, we observed that pretreatment with PFT-α and PFT-μ ameliorated Mn-induced apoptosis in PC12 cells. Collectively, these findings implicate that p53 transcription-dependent and -independent pathways may play crucial roles in the regulation of Mn-induced neuronal death.

  12. Comparison of the manganese oxygen-evolving complex in photosystem II of spinach and Synechococcus sp. with multinuclear manganese model compounds by X-ray absorption spectroscopy

    SciTech Connect

    DeRose, V.J.; Mukerji, I.; Latimer, M.J. ); Yachandra, V.K.; Klein, M.P. ); Sauer, K. Lawrence Berkeley Lab., CA )

    1994-06-15

    The evaluation of Mn X-ray absorption fine structure (EXAFS) studies on the oxygen-evolving complex (OEC) from photosystem II is described for preparations from both spinach and the cyanobacterium Synechococcus sp. poised in the S[sub 1] and S[sub 2] states. In addition to reproducing previous results suggesting the presence of bis([mu]-oxo)-bridged Mn centers in the OEC, a Fourier transform peak due to scatterers at an average distance of > 3 [angstrom] is detected in both types of preparation. In addition, subtle but reproducible changes are found in the relative amplitudes of the Fourier transform peaks due to mainly O ([approximately]1.8 [angstrom]) and Mn ([approximately] 2.7 [angstrom]) neighbors upon cryogenic advance from the S[sub 1] to the S[sub 2] state. Analysis of the peak due to scatterers at [approximately] 3 [angstrom] favors assignment to (per 4 Mn in the OEC) 1-2 heavy atom (Mn, Ca) scatterers at an average distance of 3.3-3.4 [angstrom]. The EXAFS data of several multinuclear Mn model compounds containing such scattering interactions are analyzed and compared with the data for the OEC. Structural models for the OEC are evaluated on the basis of these results. 40 refs., 9 figs., 5 tabs.

  13. Silica encapsulated manganese perovskite nanoparticles for magnetically induced hyperthermia without the risk of overheating.

    PubMed

    Kaman, O; Pollert, E; Veverka, P; Veverka, M; Hadová, E; Knízek, K; Marysko, M; Kaspar, P; Klementová, M; Grünwaldová, V; Vasseur, S; Epherre, R; Mornet, S; Goglio, G; Duguet, E

    2009-07-08

    Nanoparticles of manganese perovskite of the composition La(0.75)Sr(0.25)MnO(3) uniformly coated with silica were prepared by encapsulation of the magnetic cores (mean crystallite size 24 nm) using tetraethoxysilane followed by fractionation. The resulting hybrid particles form a stable suspension in an aqueous environment at physiological pH and possess a narrow hydrodynamic size distribution. Both calorimetric heating experiments and direct measurements of hysteresis loops in the alternating field revealed high specific power losses, further enhanced by the encapsulation procedure in the case of the coated particles. The corresponding results are discussed on the basis of complex characterization of the particles and especially detailed magnetic measurements. Moreover, the Curie temperature (335 K) of the selected magnetic cores resolves the risk of local overheating during hyperthermia treatment.

  14. Polymorphism and Formation Mechanism of Nanobipods in Manganese Sulfide Nanocrystals Induced by Temperature or Pressure

    SciTech Connect

    Yang, Xinyi; Wang, Yingnan; Wang, Kai; Sui, Yongming; Zhang, Meiguang; Li, Bing; Ma, Yanming; Liu, Bingbing; Zou, Guangtian; Zou, Bo

    2012-03-15

    Manganese sulfide (MnS) nanocrystals (NCs) with three different phases were synthesized by one-pot solvent thermal approach. The crystal structures and morphologies were investigated using powder X-ray diffraction, transmission electron microscopy, and high-resolution transmission electron microscopy. We found that the crystal structure and morphology of MnS NCs could be controlled by simply varying the reaction temperature. The detailed growth process of MnS nanobipods, including the zinc blende (ZB)-core formation and wurtzite (WZ)-arms growth, provides direct experimental evidence for the polymorphism model. Furthermore, we have studied the stability of metastable ZB- and WZ-MnS NCs under high pressure and found that ZB-nanoparticles and ZB/WZ-nanobipods are stable below their critical pressure, 5.3 and 2.9 GPa, respectively. When pressures exceed the critical point, all these metastable MnS NCs directly convert to the stable rock salt MnS.

  15. Hydrated manganese(II) phosphate (Mn₃(PO₄)₂·3H₂O) as a water oxidation catalyst.

    PubMed

    Jin, Kyoungsuk; Park, Jimin; Lee, Joohee; Yang, Ki Dong; Pradhan, Gajendra Kumar; Sim, Uk; Jeong, Donghyuk; Jang, Hae Lin; Park, Sangbaek; Kim, Donghun; Sung, Nark-Eon; Kim, Sun Hee; Han, Seungwu; Nam, Ki Tae

    2014-05-21

    The development of a water oxidation catalyst has been a demanding challenge in realizing water splitting systems. The asymmetric geometry and flexible ligation of the biological Mn4CaO5 cluster are important properties for the function of photosystem II, and these properties can be applied to the design of new inorganic water oxidation catalysts. We identified a new crystal structure, Mn3(PO4)2·3H2O, that precipitates spontaneously in aqueous solution at room temperature and demonstrated its high catalytic performance under neutral conditions. The bulky phosphate polyhedron induces a less-ordered Mn geometry in Mn3(PO4)2·3H2O. Computational analysis indicated that the structural flexibility in Mn3(PO4)2·3H2O could stabilize the Jahn-Teller-distorted Mn(III) and thus facilitate Mn(II) oxidation. This study provides valuable insights into the interplay between atomic structure and catalytic activity.

  16. Melatonin inhibits manganese-induced motor dysfunction and neuronal loss in mice: involvement of oxidative stress and dopaminergic neurodegeneration.

    PubMed

    Deng, Yu; Jiao, Congcong; Mi, Chao; Xu, Bin; Li, Yuehui; Wang, Fei; Liu, Wei; Xu, Zhaofa

    2015-02-01

    Excessive manganese (Mn) induces oxidative stress and dopaminergic neurodegeneration. However, the relationship between them during Mn neurotoxicity has not been clarified. The purpose of this study was to investigate the probable role of melatonin (MLT) against Mn-induced motor dysfunction and neuronal loss as a result of antagonizing oxidative stress and dopaminergic neurodegeneration. Mice were randomly divided into five groups as follows: control, MnCl2, low MLT + MnCl2, median MLT + MnCl2, and high MLT + MnCl2. Administration of MnCl2 (50 mg/kg) for 2 weeks significantly induced hypokinesis, dopaminergic neurons degeneration and loss, neuronal ultrastructural damage, and apoptosis in the substantia nigra and the striatum. These conditions were caused in part by the overproduction of reactive oxygen species, malondialdehyde accumulation, and dysfunction of the nonenzymatic (GSH) and enzymatic (GSH-Px, superoxide dismutase, quinone oxidoreductase 1, glutathione S-transferase, and glutathione reductase) antioxidative defense systems. Mn-induced neuron degeneration, astrocytes, and microglia activation contribute to the changes of oxidative stress markers. Dopamine (DA) depletion and downregulation of DA transporter and receptors were also found after Mn administration, this might also trigger motor dysfunction and neurons loss. Pretreatment with MLT prevented Mn-induced oxidative stress and dopaminergic neurodegeneration and inhibited the interaction between them. As a result, pretreatment with MLT significantly alleviated Mn-induced motor dysfunction and neuronal loss. In conclusion, Mn treatment resulted in motor dysfunction and neuronal loss, possibly involving an interaction between oxidative stress and dopaminergic neurodegeneration in the substantia nigra and the striatum. Pretreatment with MLT attenuated Mn-induced neurotoxicity by means of its antioxidant properties and promotion of the DA system.

  17. [The activation of microglia caused by lead and manganese co-exposure induces activation of astrocytes and decrease of glutamine synthetase activity].

    PubMed

    Guan, Ruili; Wang, Tao; Chen, Jingyuan; Luo, Wenjing; Liu, Mingchao

    2016-03-01

    acetate and 100 μmol/L manganese chloride alone and co-exposure for 24 hours did not affect astrocyte activity and its GS expression. In conditioned medium method, 10 μmol/L lead acetate and 100 μmol/L manganese chloried alone and co-exposure for 24 hours significantly induced microglia activation. After C6 cells were cultured with astrocyte normal culture medium for another 24 hours, GFAP level was significantly higher in the exposure groups than in the control group. On the contrary, GS level was significantly lower in the exposure groups than in the control group. In co-culture methods, 10 μmol/L lead acetate and 100 μmol/L manganese chloride alone and co-exposure for 24 hours significantly induced microglia activation. Then the BV2 cells were rinsed gently and co-cultured with C6 cells for 24 hours, GFAP level were significantly higher in the exposure groups than in the control group. On the contrary, GS level was significantly lower in the exposure groups than in the control group. Low-level lead or manganese alone or their co-exposure can cause microglia activation. The activated microglia can induce astrocyte activation and reduce its GS expression. Furthermore, compared with exposure alone, co-exposure had a synergistic effect.

  18. Manganese induces oligomerization to promote down-regulation of the intracellular trafficking receptor used by Shiga toxin

    PubMed Central

    Tewari, Ritika; Jarvela, Timothy; Linstedt, Adam D.

    2014-01-01

    Manganese (Mn) protects cells against lethal doses of purified Shiga toxin by causing the degradation of the cycling transmembrane protein GPP130, which the toxin uses as a trafficking receptor. Mn-induced GPP130 down-regulation, in addition to being a potential therapeutic approach against Shiga toxicosis, is a model for the study of metal-regulated protein sorting. Significantly, however, the mechanism by which Mn regulates GPP130 trafficking is unknown. Here we show that a transferable trafficking determinant within GPP130 bound Mn and that Mn binding induced GPP130 oligomerization in the Golgi. Alanine substitutions blocking Mn binding abrogated both oligomerization of GPP130 and GPP130 sorting from the Golgi to lysosomes. Further, oligomerization was sufficient because forced aggregation, using a drug-controlled polymerization domain, redirected GPP130 to lysosomes in the absence of Mn. These experiments reveal metal-induced oligomerization as a Golgi sorting mechanism for a medically relevant receptor for Shiga toxin. PMID:25079690

  19. Synthesis, characterization and magnetic properties of a manganese (II) silicate containing frustrated S=5/2 zig–zag ladders

    SciTech Connect

    Brandão, P.; Paixão, L.S.; Reis, M.S.

    2014-03-15

    The hydrothermal synthesis, structural characterization and magnetic properties of a manganese silicate with ideal formula of NaMn{sub 2}Si{sub 3}O{sub 8}(OH) is reported. This compound is a synthetic analog to the naturally occurring mineral Serandite. The crystal structure comprises MnO{sub 6} octahedra and SiO{sub 4} tetrahedra. The MnO{sub 6} share four edges with neighboring octahedra forming double chains. These chains are connected by silicate chains Si{sub 3}O{sub 8}(OH) resulting in an open framework structure with six-member ring channels where sodium ions are located. From the magnetic point of view, the intra-chain exchange between neighboring S=5/2 manganese ions is weak, partly due to the distortion observed in the octahedra, but also due to the frustrated topology of the chain. A successful fitting of the magnetic susceptibility was obtained by considering a double chain numerical model with Monte Carlo derived empirical parameters. -- Graphical abstract: A manganese silicate prepared hydrothermally with formula NaMn{sub 2}Si{sub 3}O{sub 8}(OH) possessing the structure of the mineral Serandite contains doubled chains of edge-sharing MnO{sub 6} octahedra. The magnetic susceptibility was measured and shows an antiferromagnetic behavior. Highlights: • Characterization of a synthetic analog to the mineral Serandite: NaMn{sub 2}Si{sub 3}O{sub 8}(OH). • Fitting of the magnetic susceptibility considering a classical regular chain. • Weak metal–oxygen–metal super-exchange interactions; antiferromagnetic in nature. • Elevated degree of frustration along the chain, without sign of interchain ordering.

  20. Ammonia binding to the oxygen-evolving complex of photosystem II identifies the solvent-exchangeable oxygen bridge (μ-oxo) of the manganese tetramer

    PubMed Central

    Pérez Navarro, Montserrat; Ames, William M.; Nilsson, Håkan; Lohmiller, Thomas; Pantazis, Dimitrios A.; Rapatskiy, Leonid; Nowaczyk, Marc M.; Neese, Frank; Boussac, Alain; Messinger, Johannes; Lubitz, Wolfgang; Cox, Nicholas

    2013-01-01

    The assignment of the two substrate water sites of the tetra-manganese penta-oxygen calcium (Mn4O5Ca) cluster of photosystem II is essential for the elucidation of the mechanism of biological O-O bond formation and the subsequent design of bio-inspired water-splitting catalysts. We recently demonstrated using pulsed EPR spectroscopy that one of the five oxygen bridges (μ-oxo) exchanges unusually rapidly with bulk water and is thus a likely candidate for one of the substrates. Ammonia, a water analog, was previously shown to bind to the Mn4O5Ca cluster, potentially displacing a water/substrate ligand [Britt RD, et al. (1989) J Am Chem Soc 111(10):3522–3532]. Here we show by a combination of EPR and time-resolved membrane inlet mass spectrometry that the binding of ammonia perturbs the exchangeable μ-oxo bridge without drastically altering the binding/exchange kinetics of the two substrates. In combination with broken-symmetry density functional theory, our results show that (i) the exchangable μ-oxo bridge is O5 {using the labeling of the current crystal structure [Umena Y, et al. (2011) Nature 473(7345):55–60]}; (ii) ammonia displaces a water ligand to the outer manganese (MnA4-W1); and (iii) as W1 is trans to O5, ammonia binding elongates the MnA4-O5 bond, leading to the perturbation of the μ-oxo bridge resonance and to a small change in the water exchange rates. These experimental results support O-O bond formation between O5 and possibly an oxyl radical as proposed by Siegbahn and exclude W1 as the second substrate water. PMID:24023065

  1. Dinuclear manganese(II) complexes of hexaazamacrocycles bearing N-benzoylated pendant separated by aromatic spacers: Antibacterial, DNA interaction, cytotoxic and molecular docking studies.

    PubMed

    Arthi, P; Shobana, S; Srinivasan, P; Prabhu, D; Arulvasu, C; Kalilur Rahiman, A

    2015-12-01

    Three new homodinuclear manganese(II) complexes of the type [Mn2L(1-3)(ClO4)(H2O)](ClO4)3 (1-3) have been synthesized via cyclocondensation of terephthalaldehyde with three different benzoylated pendants in the presence of manganese(II) perchlorate and characterized by spectroscopic methods. Cyclic voltammetric investigation of complexes (1-3) depict two quasi-reversible one electron reduction processes in the cathodic potential region (E(1)pc=-0.73 to-0.83 V, E(2)pc=-1.31 to -1.40 V) and two quasi-reversible one electron oxidation processes in the anodic potential region (E(1)pa=1.03 to 1.10 V, E(2)pa=1.69 to 1.77 V). Electronic absorption spectra of the complexes suggested tetrahedral geometry around the central metal ion. The observed low magnetic moment values (μeff, 5.60-5.68 B.M.) of the complexes indicate the presence of an antiferromagnetic spin-exchange interaction between two metal centers, which was also supported by the broad EPR signal. All the compounds were tested for antibacterial activity against Gram (-ve) and Gram (+ve) bacterial strains. The binding studies of complexes with CT-DNA suggested minor-groove mode of interaction. Molecular docking studies were carried out in order to find the binding affinity of complexes with DNA and protein EGFR Kinase. The complexes are stabilized by additional electrostatic and van der Waals interaction with the DNA, and support minor groove mode of binding. The cleavage activity of complexes on pBR322 plasmid DNA displays efficient activity through a mechanistic pathway involving hydroxyl radicals. The cytotoxicity of complexes 2 and 3 have been tested against human liver adenocarcinoma (HepG2) cell line. Nuclear-chromatin cleavage has also been observed with propidium iodide (PI) staining and alkaline single-cell gel electrophoresis (comet assay) techniques.

  2. Ammonia binding to the oxygen-evolving complex of photosystem II identifies the solvent-exchangeable oxygen bridge (μ-oxo) of the manganese tetramer.

    PubMed

    Pérez Navarro, Montserrat; Ames, William M; Nilsson, Håkan; Lohmiller, Thomas; Pantazis, Dimitrios A; Rapatskiy, Leonid; Nowaczyk, Marc M; Neese, Frank; Boussac, Alain; Messinger, Johannes; Lubitz, Wolfgang; Cox, Nicholas

    2013-09-24

    The assignment of the two substrate water sites of the tetra-manganese penta-oxygen calcium (Mn4O5Ca) cluster of photosystem II is essential for the elucidation of the mechanism of biological O-O bond formation and the subsequent design of bio-inspired water-splitting catalysts. We recently demonstrated using pulsed EPR spectroscopy that one of the five oxygen bridges (μ-oxo) exchanges unusually rapidly with bulk water and is thus a likely candidate for one of the substrates. Ammonia, a water analog, was previously shown to bind to the Mn4O5Ca cluster, potentially displacing a water/substrate ligand [Britt RD, et al. (1989) J Am Chem Soc 111(10):3522-3532]. Here we show by a combination of EPR and time-resolved membrane inlet mass spectrometry that the binding of ammonia perturbs the exchangeable μ-oxo bridge without drastically altering the binding/exchange kinetics of the two substrates. In combination with broken-symmetry density functional theory, our results show that (i) the exchangable μ-oxo bridge is O5 {using the labeling of the current crystal structure [Umena Y, et al. (2011) Nature 473(7345):55-60]}; (ii) ammonia displaces a water ligand to the outer manganese (MnA4-W1); and (iii) as W1 is trans to O5, ammonia binding elongates the MnA4-O5 bond, leading to the perturbation of the μ-oxo bridge resonance and to a small change in the water exchange rates. These experimental results support O-O bond formation between O5 and possibly an oxyl radical as proposed by Siegbahn and exclude W1 as the second substrate water.

  3. Microstructure Evolution and Mechanical Behavior of a Hot-Rolled High-Manganese Dual-Phase Transformation-Induced Plasticity/Twinning-Induced Plasticity Steel

    NASA Astrophysics Data System (ADS)

    Fu, Liming; Shan, Mokun; Zhang, Daoda; Wang, Huanrong; Wang, Wei; Shan, Aidang

    2017-02-01

    The microstructures and deformation behavior were studied in a high-temperature annealed high-manganese dual-phase (28 vol pct δ-ferrite and 72 vol pct γ-austenite) transformation-induced plasticity/twinning-induced plasticity (TRIP/TWIP) steel. The results showed that the steel exhibits a special Lüders-like yielding phenomenon at room temperature (RT) and 348 K (75 °C), while it shows continuous yielding at 423 K, 573 K and 673 K (150 °C, 300 °C and 400 °C) deformation. A significant TRIP effect takes place during Lüders-like deformation at RT and 348 K (75 °C) temperatures. Semiquantitative analysis of the TRIP effect on the Lüders-like yield phenomenon proves that a softening effect of the strain energy consumption of strain-induced transformation is mainly responsible for this Lüders-like phenomenon. The TWIP mechanism dominates the 423 K (150 °C) deformation process, while the dislocation glide controls the plasticity at 573 K (300 °C) deformation. The delta-ferrite, as a hard phase in annealed dual-phase steel, greatly affects the mechanical stability of austenite due to the heterogeneous strain distribution between the two phases during deformation. A delta-ferrite-aided TRIP effect, i.e., martensite transformation induced by localized strain concentration of the hard delta-ferrite, is proposed to explain this kind of Lüders-like phenomenon. Moreover, the tensile curve at RT exhibits an upward curved behavior in the middle deformation stage, which is principally attributed to the deformation twinning of austenite retained after Lüders-like deformation. The combination of the TRIP effect during Lüders-like deformation and the subsequent TWIP effect greatly enhances the ductility in this annealed high-manganese dual-phase TRIP/TWIP steel.

  4. Microstructure Evolution and Mechanical Behavior of a Hot-Rolled High-Manganese Dual-Phase Transformation-Induced Plasticity/Twinning-Induced Plasticity Steel

    NASA Astrophysics Data System (ADS)

    Fu, Liming; Shan, Mokun; Zhang, Daoda; Wang, Huanrong; Wang, Wei; Shan, Aidang

    2017-05-01

    The microstructures and deformation behavior were studied in a high-temperature annealed high-manganese dual-phase (28 vol pct δ-ferrite and 72 vol pct γ-austenite) transformation-induced plasticity/twinning-induced plasticity (TRIP/TWIP) steel. The results showed that the steel exhibits a special Lüders-like yielding phenomenon at room temperature (RT) and 348 K (75 °C), while it shows continuous yielding at 423 K, 573 K and 673 K (150 °C, 300 °C and 400 °C) deformation. A significant TRIP effect takes place during Lüders-like deformation at RT and 348 K (75 °C) temperatures. Semiquantitative analysis of the TRIP effect on the Lüders-like yield phenomenon proves that a softening effect of the strain energy consumption of strain-induced transformation is mainly responsible for this Lüders-like phenomenon. The TWIP mechanism dominates the 423 K (150 °C) deformation process, while the dislocation glide controls the plasticity at 573 K (300 °C) deformation. The delta-ferrite, as a hard phase in annealed dual-phase steel, greatly affects the mechanical stability of austenite due to the heterogeneous strain distribution between the two phases during deformation. A delta-ferrite-aided TRIP effect, i.e., martensite transformation induced by localized strain concentration of the hard delta-ferrite, is proposed to explain this kind of Lüders-like phenomenon. Moreover, the tensile curve at RT exhibits an upward curved behavior in the middle deformation stage, which is principally attributed to the deformation twinning of austenite retained after Lüders-like deformation. The combination of the TRIP effect during Lüders-like deformation and the subsequent TWIP effect greatly enhances the ductility in this annealed high-manganese dual-phase TRIP/TWIP steel.

  5. Biological manganese removal from acid mine drainage in constructed wetlands and prototype bioreactors.

    PubMed

    Hallberg, Kevin B; Johnson, D Barrie

    2005-02-01

    Mine drainage waters vary considerably in the range and concentration of heavy metals they contain. Besides iron, manganese is frequently present at elevated concentrations in waters draining both coal and metal mines. Passive treatment systems (aerobic wetlands and compost bioreactors) are designed to remove iron by biologically induced oxidation/precipitation. Manganese, however, is problematic as it does not readily form sulfidic minerals and requires elevated pH (>8) for abiotic oxidation of Mn (II) to insoluble Mn (IV). As a result, manganese removal in passive remediation systems is often less effective than removal of iron. This was found to be the case at the pilot passive treatment plant (PPTP) constructed to treat water draining the former Wheal Jane tin mine in Cornwall, UK, where effective removal of manganese occurred only in one of the three rock filter components of the composite systems over a 1-year period of monitoring. Water in the two rock filter systems where manganese removal was relatively poor was generally manganese removal were due to variable performances in the compost bioreactors that feed the rock filter units in the composite passive systems at Wheal Jane. An alternative approach for removing soluble manganese from mine waters, using fixed bed bioreactors, was developed. Ferromanganese nodules (about 2 cm diameter), collected from an abandoned mine adit in north Wales, were used to inoculate the bioreactors (working volume ca. 700 ml). Following colonization by manganese-oxidizing microbes, the aerated bioreactor catalysed the removal of soluble manganese, via oxidation of Mn (II) and precipitation of the resultant Mn (IV) in the bioreactor, in synthetic media and mine water from the Wheal Jane PPTP. Such an approach has potential application for removing soluble Mn from mine streams and other Mn

  6. Upregulation of mitochondrial protease HtrA2/Omi contributes to manganese-induced neuronal apoptosis in rat brain striatum.

    PubMed

    Jiang, J K; Ma, X; Wu, Q Y; Qian, W B; Wang, N; Shi, S S; Han, J L; Zhao, J Y; Jiang, S Y; Wan, C H

    2014-05-30

    Manganese (Mn) is an essential trace element that is required for normal brain functioning. However, excessive intake of Mn has been known to lead to neuronal loss and clinical symptoms resembling idiopathic Parkinson's disease (IPD), whose precise molecular mechanism remains largely elusive. In the study, we established a Mn-exposed rat model and identified a mitochondrial protease, the mature form of high temperature requirement A2 (HtrA2/Omi), which was significantly upregulated in rat brain striatum after Mn exposure. Western blot and immunohistochemical analyses revealed that the expression of mature HtrA2 was remarkably increased following Mn exposure. In addition, immunofluorescence assay demonstrated that overexposure to Mn could lead to significant elevation in the number of HtrA2-positive neurons. Accordingly, the expression of X-linked inhibitor of apoptosis protein (XIAP), a well-characterized target of HtrA2-mediated proteolysis, was progressively decreased following Mn exposure, and was correlated with increased level of active caspase-3. Further, we showed that Mn exposure decreased the viability and induced apparent apoptosis of NFG-differentiated PC12 cells. Importantly, the expression of HtrA2 was progressively increased, whereas the level of cellular XIAP was reduced during Mn-induced apoptosis. In addition, blockage of HtrA2 activity with UCF-101 restored Mn-induced reduction in XIAP expression. Finally, we observed that UCF-101 treatment ameliorated Mn-induced apoptosis in PC12 cells. Collectively, these findings suggested that upregulated HtrA2 played a role in Mn-induced neuronal death in brain striatum.

  7. Downregulation of Mfn2 participates in manganese-induced neuronal apoptosis in rat striatum and PC12 cells.

    PubMed

    Liu, Xinhang; Yang, Jianbin; Lu, Chunhua; Jiang, Shengyang; Nie, Xiaoke; Han, Jingling; Yin, Lifeng; Jiang, Junkang

    2017-02-21

    Manganese (Mn) is a widely distributed trace element that is essential for normal brain function and development. However, chronic exposure to excessive Mn has been known to lead to neuronal loss and manganism, a disease with debilitating motor and cognitive deficits, whose clinical syndrome resembling idiopathic Parkinson's disease (IPD). However, the precise molecular mechanism underlying Mn neurotoxicity remains largely unclear. Accumulating evidence indicates that abnormal mitochondrial functionality is an early and causal event in Mn-induced neurodegeneration and apoptosis. Here, we investigated whether Mitofusin 2 (Mfn2), a highly conserved dynamin-related protein (DRP), played a role in the regulation of Mn-induced neuronal apoptosis. We revealed that Mfn2 was significantly dysregulated in rat striatum and PC12 neuronal-like cells following Mn exposure. Western blot analysis revealed that the expression of Mfn2 was remarkably decreased following different concentrations of Mn exposure. Immunohistochemistry analysis confirmed a remarkable downregulation of Mfn2 in rat striatum after Mn exposure. Immunofluorescent staining showed that Mfn2 was expressed predominantly in neurons, and neuronal loss of Mfn2 was associated with the expression of active caspase-3 following Mn exposure. Importantly, overexpression of Mfn2 apparently attenuated Mn-induced neuronal apoptosis. Notably, treatment with caspase-3 inhibitor Ac-DEVD-CH could not rescue Mn-induced downregulation of Mfn2, suggesting that Mn-induced mfn2 occurs prior to neuronal apoptosis. Taken together, these results indicated that down-regulated expression of Mfn2 might contribute to the pathological processes underlying Mn neurotoxicity.

  8. Angiotensin II induces apoptosis in renal proximal tubular cells.

    PubMed

    Bhaskaran, Madhu; Reddy, Krishna; Radhakrishanan, Neetu; Franki, Nicholas; Ding, Guohua; Singhal, Pravin C

    2003-05-01

    ANG II has been demonstrated to play a role in the progression of tubulointerstial injury. We studied the direct effect of ANG II on apoptosis of cultured rat renal proximal tubular epithelial cells (RPTECs). ANG II promoted RPTEC apoptosis in a dose- and time-dependent manner. This effect of ANG II was attenuated by anti-transforming growth factor (TGF)-beta antibody. Moreover, TGF-beta triggered RPTEC apoptosis in a dose-dependent manner. ANG II also enhanced RPTEC expression of Fas and Fas ligand (FasL); furthermore, anti-FasL antibody attenuated ANG II-induced RPTEC apoptosis. In addition, ANG II increased RPTEC expression of Bax, a cell death protein. Both ANG II type 1 (AT(1)) and type 2 (AT(2)) receptor blockers inhibited ANG II-induced RPTEC apoptosis. SB-202190, an inhibitor of p38 MAPK phosphorylation, and caspase-3 inhibitor also attenuated ANG II-induced RPTEC apoptosis. ANG II enhanced RPTEC heme oxygenase (HO)-1 expression. Interestingly, pretreatment with hemin as well as curcumin (inducers of HO-1) inhibited the ANG II-induced tubular cell apoptosis; conversely, pretreatment with zinc protoporphyrin, an inhibitor of HO-1 expression, promoted the effect of ANG II. These results suggest that ANG II-induced apoptosis is mediated via both AT(1) and AT(2) receptors through the generation of TGF-beta, followed by the transcription of cell death genes such as Fas, FasL, and Bax. Modulation of tubular cell expression of HO-1 has an inverse relationship with the ANG II-induced tubular cell apoptosis.

  9. Systems-wide analysis of manganese deficiency-induced changes in gene activity of Arabidopsis roots

    PubMed Central

    Rodríguez-Celma, Jorge; Tsai, Yi-Hsiu; Wen, Tuan-Nan; Wu, Yu-Ching; Curie, Catherine; Schmidt, Wolfgang

    2016-01-01

    Manganese (Mn) is pivotal for plant growth and development, but little information is available regarding the strategies that evolved to improve Mn acquisition and cellular homeostasis of Mn. Using an integrated RNA-based transcriptomic and high-throughput shotgun proteomics approach, we generated a comprehensive inventory of transcripts and proteins that showed altered abundance in response to Mn deficiency in roots of the model plant Arabidopsis. A suite of 22,385 transcripts was consistently detected in three RNA-seq runs; LC-MS/MS-based iTRAQ proteomics allowed the unambiguous determination of 11,606 proteins. While high concordance between mRNA and protein expression (R = 0.87) was observed for transcript/protein pairs in which both gene products accumulated differentially upon Mn deficiency, only approximately 10% of the total alterations in the abundance of proteins could be attributed to transcription, indicating a large impact of protein-level regulation. Differentially expressed genes spanned a wide range of biological functions, including the maturation, translation, and transport of mRNAs, as well as primary and secondary metabolic processes. Metabolic analysis by UPLC-qTOF-MS revealed that the steady-state levels of several major glucosinolates were significantly altered upon Mn deficiency in both roots and leaves, possibly as a compensation for increased pathogen susceptibility under conditions of Mn deficiency. PMID:27804982

  10. Reduced hippocampal manganese-enhanced MRI (MEMRI) signal during pilocarpine-induced status epilepticus: edema or apoptosis?

    PubMed

    Malheiros, Jackeline Moraes; Persike, Daniele Suzete; Castro, Leticia Urbano Cardoso de; Sanches, Talita Rojas Cunha; Andrade, Lúcia da Conceição; Tannús, Alberto; Covolan, Luciene

    2014-05-01

    Manganese-enhanced MRI (MEMRI) has been considered a surrogate marker of Ca(+2) influx into activated cells and tracer of neuronal active circuits. However, the induction of status epilepticus (SE) by kainic acid does not result in hippocampal MEMRI hypersignal, in spite of its high cell activity. Similarly, short durations of status (5 or 15min) induced by pilocarpine did not alter the hippocampal MEMRI, while 30 min of SE even reduced MEMRI signal Thus, this study was designed to investigate possible explanations for the absence or decrease of MEMRI signal after short periods of SE. We analyzed hippocampal caspase-3 activation (to evaluate apoptosis), T2 relaxometry (tissue water content) and aquaporin 4 expression (water-channel protein) of rats subjected to short periods of pilocarpine-induced SE. For the time periods studied here, apoptotic cell death did not contribute to the decrease of the hippocampal MEMRI signal. However, T2 relaxation was higher in the group of animals subjected to 30min of SE than in the other SE or control groups. This result is consistent with higher AQP-4 expression during the same time period. Based on apoptosis and tissue water content analysis, the low hippocampal MEMRI signal 30min after SE can potentially be attributed to local edema rather than to cell death.

  11. Manganese-Induced Neurotoxicity and Alterations in Gene Expression in Human Neuroblastoma SH-SY5Y Cells.

    PubMed

    Gandhi, Deepa; Sivanesan, Saravanadevi; Kannan, Krishnamurthi

    2017-09-15

    Manganese (Mn) is an essential trace element required for many physiological functions including proper biochemical and cellular functioning of the central nervous system (CNS). However, exposure to excess level of Mn through occupational settings or from environmental sources has been associated with neurotoxicity. The cellular and molecular mechanism of Mn-induced neurotoxicity remains unclear. In the current study, we investigated the effects of 30-day exposure to a sub-lethal concentration of Mn (100 μM) in human neuroblastoma cells (SH-SY5Y) using transcriptomic approach. Microarray analysis revealed differential expression of 1057 transcripts in Mn-exposed SH-SY5Y cells as compared to control cells. Gene functional annotation cluster analysis exhibited that the differentially expressed genes were associated with several biological pathways. Specifically, genes involved in neuronal pathways including neuron differentiation and development, regulation of neurogenesis, synaptic transmission, and neuronal cell death (apoptosis) were found to be significantly altered. KEGG pathway analysis showed upregulation of p53 signaling pathways and neuroactive ligand-receptor interaction pathways, and downregulation of neurotrophin signaling pathway. On the basis of the gene expression profile, possible molecular mechanisms underlying Mn-induced neuronal toxicity were predicted.

  12. Bavachalcone-induced manganese superoxide dismutase expression through the AMP-activated protein kinase pathway in human endothelial cells.

    PubMed

    Dang, Yanqi; Ling, Shuang; Duan, Ju; Ma, Jing; Ni, Rongzhen; Xu, Jin-Wen

    2015-01-01

    Mitochondrial oxidative stress has been suggested as a major etiological factor in cardiovascular diseases. Manganese superoxide dismutase (MnSOD) is an essential antioxidant mitochondrial enzyme. Although polyphenols can induce MnSOD expression, their mechanism of action remains unclear. We examined the effect of bavachalcone, a bioactive compound isolated from Psoralea corylifolia, on MnSOD protein expression and explored whether this effect is mediated through the AMP-activated protein kinase (AMPK) signaling pathway. Our data showed that bavachalcone enhanced the luciferase activity of the MnSOD promoter and increased MnSOD mRNA and protein expressions. Moreover, bavachalcone suppressed the mitochondrial superoxide production in endothelial cells. Conversely, bavachalcone stimulated liver kinase B1 and AMPKα phosphorylation. mRNA interference by using short hairpin RNA (shRNA) of AMPK inhibited bavachalcone-induced MnSOD expression. A-769662, an AMPK activator, also stimulated AMPK activity and increased MnSOD expression. Furthermore, AMPK knockdown by shRNA-AMPK reversed the inhibitory effects of bavachalcone on mitochondrial superoxide production in endothelial cells. These findings indicate that bavachalcone can protect the endothelial function by increasing AMPK activity and MnSOD expression and reducing mitochondrial oxidative stress. .

  13. Manganese-induced cadmium stress tolerance in rice seedlings: Coordinated action of antioxidant defense, glyoxalase system and nutrient homeostasis.

    PubMed

    Rahman, Anisur; Nahar, Kamrun; Hasanuzzaman, Mirza; Fujita, Masayuki

    The accumulation of cadmium (Cd) alters different physiological and biochemical attributes that affect plant growth and yield. In our study, we investigated the regulatory role of supplemental manganese (Mn) on hydroponically grown rice (Oryza sativa L. cv. BRRI dhan29) seedlings under Cd-stress conditions. Exposure of 14-d-old seedlings to 0.3mM CdCl2 for three days caused growth inhibition, chlorosis, nutrient imbalance, and higher Cd accumulation. Higher Cd uptake caused oxidative stress through lipid peroxidation, loss of plasma membrane integrity, and overproduction of reactive oxygen species (ROS) and methylglyoxal (MG). The exogenous application of 0.3mM MnSO4 to Cd-treated seedlings partly recovered Cd-induced water loss, chlorosis, growth inhibition, and nutrient imbalance by reducing Cd uptake and its further translocation to the upper part of the plant. Supplemental Mn also reduced Cd-induced oxidative damage and lipid peroxidation by improved antioxidant defense and glyoxalase systems through enhancing ROS and MG detoxification, respectively. Copyright © 2016 Académie des sciences. Published by Elsevier SAS. All rights reserved.

  14. Manganese Superoxide Dismutase Gene Expression Is Induced by Nanog and Oct4, Essential Pluripotent Stem Cells' Transcription Factors.

    PubMed

    Solari, Claudia; Vázquez Echegaray, Camila; Cosentino, María Soledad; Petrone, María Victoria; Waisman, Ariel; Luzzani, Carlos; Francia, Marcos; Villodre, Emilly; Lenz, Guido; Miriuka, Santiago; Barañao, Lino; Guberman, Alejandra

    2015-01-01

    Pluripotent stem cells possess complex systems that protect them from oxidative stress and ensure genomic stability, vital for their role in development. Even though it has been reported that antioxidant activity diminishes along stem cell differentiation, little is known about the transcriptional regulation of the involved genes. The reported modulation of some of these genes led us to hypothesize that some of them could be regulated by the transcription factors critical for self-renewal and pluripotency in embryonic stem cells (ESCs) and in induced pluripotent stem cells (iPSCs). In this work, we studied the expression profile of multiple genes involved in antioxidant defense systems in both ESCs and iPSCs. We found that Manganese superoxide dismutase gene (Mn-Sod/Sod2) was repressed during diverse differentiation protocols showing an expression pattern similar to Nanog gene. Moreover, Sod2 promoter activity was induced by Oct4 and Nanog when we performed a transactivation assay using two different reporter constructions. Finally, we studied Sod2 gene regulation by modulating the expression of Oct4 and Nanog in ESCs by shRNAs and found that downregulation of any of them reduced Sod2 expression. Our results indicate that pluripotency transcription factors positively modulate Sod2 gene transcription.

  15. Manganese Superoxide Dismutase Gene Expression Is Induced by Nanog and Oct4, Essential Pluripotent Stem Cells’ Transcription Factors

    PubMed Central

    Solari, Claudia; Vázquez Echegaray, Camila; Cosentino, María Soledad; Petrone, María Victoria; Waisman, Ariel; Luzzani, Carlos; Francia, Marcos; Villodre, Emilly; Lenz, Guido; Miriuka, Santiago; Barañao, Lino; Guberman, Alejandra

    2015-01-01

    Pluripotent stem cells possess complex systems that protect them from oxidative stress and ensure genomic stability, vital for their role in development. Even though it has been reported that antioxidant activity diminishes along stem cell differentiation, little is known about the transcriptional regulation of the involved genes. The reported modulation of some of these genes led us to hypothesize that some of them could be regulated by the transcription factors critical for self-renewal and pluripotency in embryonic stem cells (ESCs) and in induced pluripotent stem cells (iPSCs). In this work, we studied the expression profile of multiple genes involved in antioxidant defense systems in both ESCs and iPSCs. We found that Manganese superoxide dismutase gene (Mn-Sod/Sod2) was repressed during diverse differentiation protocols showing an expression pattern similar to Nanog gene. Moreover, Sod2 promoter activity was induced by Oct4 and Nanog when we performed a transactivation assay using two different reporter constructions. Finally, we studied Sod2 gene regulation by modulating the expression of Oct4 and Nanog in ESCs by shRNAs and found that downregulation of any of them reduced Sod2 expression. Our results indicate that pluripotency transcription factors positively modulate Sod2 gene transcription. PMID:26642061

  16. Drinking induced by angiotensin II in fishes.

    PubMed

    Kobayashi, H; Uemura, H; Takei, Y; Itatsu, N; Ozawa, M; Ichinohe, K

    1983-02-01

    Among 20 species of freshwater fishes examined, Pseudorasbora parva, Rhodeus ocellatus, Cobitis anguillicaudatus, Carassius auratus, Oryzias latipes, Gambusia affinis, and Gyrinocheilus anymonieri were found to drink water like seawater fishes, while 13 remaining species did not drink. For fish species found exclusively in fresh water, angiotensin II (AII) treatment did not induce drinking. In contrast, those freshwater fishes which survive in estuarine brackish water (Leuciscus hakonensis, C. carassius, Parasilurus asotus, G. affinis, Chaenogobius annularis, Tridentiger obscurus, and G. anymonieri responded to AII by drinking. Furthermore, some freshwater fishes which survive either in hypertonic water (C. auratus) or in sea water (Anguilla japonica and O. latipes) also responded to AII by drinking. Of 17 seawater fishes examined, Eptatretus burgeri, Triakis scyllia, and Heterodontus japonicus failed to drink water, and for Trachurus japonicus, Platichthys bicoloratus, and Glossogobius giuris fasciatopunctatus, water intake was minor (similar to freshwater fishes). The 11 remaining seawater fishes drank water. AII did not induce drinking in fishes living exclusively in sea water. However, seawater fishes which survive either in tide pools (Chasmichthys dolichognathus gulosus) or in brackish water (Sillago japonica, Mugil cephalus, G. giuris fasciatopunctatus) responded to AII by drinking. P. bicoloratus, Acanthopagrus schlegeli, and Fugu niphobles were exceptional, in that they survive in brackish water, but did not respond to AII. Although some exceptions exist, it is generally concluded that a drinking response to AII is characteristic of fishes which encounter water more hypertonic than that in which they typically reside. Accordingly, a drinking mechanism induced by AII may be a compensatory emergency reaction to dehydration stress.

  17. Crystal structures of the water and acetone monosolvates of bis-[4'-(pyridin-4-yl)-2,2':6',2''-terpyridine]-manganese(II) bis-(hexa-fluorido-phosphate).

    PubMed

    Lourenço, Leandro M O; Almeida Paz, Filipe A; Fernandes, José A

    2015-04-01

    The crystal structures of bis-[4'-(pyridin-4-yl)-2,2':6',2''-terpyridine]-man-gan-ese(II) bis-(hexa-fluorido-phosphate) monohydrate, [Mn(C20H14N4)2](PF6)2·H2O, (1), and bis-[4'-(pyridin-4-yl)-2,2':6',2''-terpyridine]-manganese(II) bis(hexa-fluorido-phosphate) acetone monosolvate, (2), [Mn(C20H14N4)2](PF6)2·CH3COCH3, are described. At 150 K, (1) and (2) have monoclinic (P21/c) and ortho-rhom-bic (C2221) symmetries, respectively. Both structures exhibit octahedrally coordinated Mn(II) atoms and disorder. They display weak inter-actions, such as C-H⋯F, C-H⋯N, C-H⋯π, F⋯π and π-π. The twofold rotation axis in the molecule of (2) is coincident with a twofold rotation axis of the crystal.

  18. Synthesis, physico-chemical studies of manganese(II), cobalt(II), nickel(II), copper(II) and zinc(II) complexes with some p-substituted acetophenone benzoylhydrazones and their antimicrobial activity.

    PubMed

    Singh, Vinod P; Singh, Shweta; Katiyar, Anshu

    2009-04-01

    Complexes of the type [M(pabh)(H2O)Cl], [M(pcbh)(H2O)Cl] and [M(Hpabh)(H2O)2 (SO4)] where, M = Mn(II), Co(II), Ni(II), Cu(II) and Zn(II); Hpabh = p-amino acetophenone benzoyl hydrazone and Hpcbh = p-chloro acetophenone benzoyl hydrazone have been synthesized and characterized with the help of elemental analyses, electrical conductance, magnetic susceptibility measurements, electronic, ESR and IR spectra, thermal (TGA & DTA) and X-ray diffraction studies. Co(II), Ni(II) and Cu(II) chloride complexes are square planar, whereas their sulfate complexes have spin-free octahedral geometry. ESR spectra of Cu(II) complexes with Hpabh are axial and suggest d(x(2)-y(2) as the ground state. The ligand is bidentate bonding through > C = N--and deprotonated enolate group in all the chloro complexes, whereas, >C = N and >C = O groups in all the sulfato complexes. Thermal studies (TGA & DTA) on [Cu(Hpabh)(H2O)2(SO4)] indicate a multistep decomposition pattern, which are both exothermic and endothermic in nature. X-ray powder diffraction parameters for [Co(pabh)(H2O)Cl] and [Ni(Hpabh)(H2O)2(SO4)] correspond to tetragonal and orthorhombic crystal lattices, respectively. The ligands as well as their complexes show a significant antifungal and antibacterial activity. The metal complexes are more active than the ligand.

  19. Pivotal roles of p53 transcription-dependent and -independent pathways in manganese-induced mitochondrial dysfunction and neuronal apoptosis

    SciTech Connect

    Wan, Chunhua; Ma, Xa; Shi, Shangshi; Zhao, Jianya; Nie, Xiaoke; Han, Jingling; Xiao, Jing; Wang, Xiaoke; Jiang, Shengyang; Jiang, Junkang

    2014-12-15

    Chronic exposure to excessive manganese (Mn) has been known to lead to neuronal loss and a clinical syndrome resembling idiopathic Parkinson's disease (IPD). p53 plays an integral role in the development of various human diseases, including neurodegenerative disorders. However, the role of p53 in Mn-induced neuronal apoptosis and neurological deficits remains obscure. In the present study, we showed that p53 was critically involved in Mn-induced neuronal apoptosis in rat striatum through both transcription-dependent and -independent mechanisms. Western blot and immunohistochemistrical analyses revealed that p53 was remarkably upregulated in the striatum of rats following Mn exposure. Coincidentally, increased level of cleaved PARP, a hallmark of apoptosis, was observed. Furthermore, using nerve growth factor (NGF)-differentiated PC12 cells as a neuronal cell model, we showed that Mn exposure decreased cell viability and induced apparent apoptosis. Importantly, p53 was progressively upregulated, and accumulated in both the nucleus and the cytoplasm. The cytoplasmic p53 had a remarkable distribution in mitochondria, suggesting an involvement of p53 mitochondrial translocation in Mn-induced neuronal apoptosis. In addition, Mn-induced impairment of mitochondrial membrane potential (ΔΨm) could be partially rescued by pretreatment with inhibitors of p53 transcriptional activity and p53 mitochondrial translocation, Pifithrin-α (PFT-α) and Pifithrin-μ (PFT-μ), respectively. Moreover, blockage of p53 activities with PFT-α and PFT-μ significantly attenuated Mn-induced reactive oxidative stress (ROS) generation and mitochondrial H{sub 2}O{sub 2} production. Finally, we observed that pretreatment with PFT-α and PFT-μ ameliorated Mn-induced apoptosis in PC12 cells. Collectively, these findings implicate that p53 transcription-dependent and -independent pathways may play crucial roles in the regulation of Mn-induced neuronal death. - Highlights: • p53 is robustly

  20. Manganese mineralogy and diagenesis in the sedimentary rock record

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

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

  1. Unveiling the Origin of Work Hardening Behavior in an Ultrafine-Grained Manganese Transformation-Induced Plasticity Steel by Hydrogen Investigation

    NASA Astrophysics Data System (ADS)

    Zhu, Xu; Li, Wei; Zhao, Hongshan; Han, Qihang; Wang, Li; Jiao, Huisheng; Jin, Xuejun

    2016-09-01

    To reveal the origin of work hardening behavior in an ultrafine-grained manganese transformation-induced plasticity (TRIP) steel, specific experiments were designed with the assistance of hydrogen. Although the effect of hydrogen on the austenite transformation was negligible, the work hardening rate ( Θ) was apparently reduced for hydrogenated samples, indicating that TRIP effect cannot account for the high Θ alone. The collaborative effect of dislocation accumulation in ferrite and austenite transformation is proposed to explain the responsible mechanism.

  2. Manganese-induced sex-specific gut microbiome perturbations in C57BL/6 mice.

    PubMed

    Chi, Liang; Gao, Bei; Bian, Xiaoming; Tu, Pengcheng; Ru, Hongyu; Lu, Kun

    2017-09-15

    Overexposure to manganese (Mn) leads to toxic effects, such as promoting the development of Parkinson's-like neurological disorders. The gut microbiome is deeply involved in immune development, host metabolism, and xenobiotics biotransformation, and significantly influences central nervous system (CNS) via the gut-brain axis, i.e. the biochemical signaling between the gastrointestinal tract and the CNS. However, it remains unclear whether Mn can affect the gut microbiome and its metabolic functions, particularly those linked to neurotoxicity. In addition, sex-specific effects of Mn have been reported, with no mechanism being identified yet. Recently, we have shown that the gut microbiome is largely different between males and females, raising the possibility that differential gut microbiome responses may contribute to sex-selective toxicity of Mn. Here, we applied high-throughput sequencing and gas chromatography-mass spectrometry (GC-MS) metabolomics to explore how Mn(2+) exposure affects the gut microbiome and its metabolism in C57BL/6 mice. Mn(2+) exposure perturbed the gut bacterial compositions, functional genes and fecal metabolomes in a highly sex-specific manner. In particular, bacterial genes and/or key metabolites of neurotransmitter synthesis and pro-inflammatory mediators are significantly altered by Mn(2+) exposure, which can potentially affect chemical signaling of gut-brain interactions. Likewise, functional genes involved in iron homeostasis, flagellar motility, quorum sensing, and Mn transportation/oxidation are also widely changed by Mn(2+) exposure. Taken together, this study has demonstrated that Mn(2+) exposure perturbs the gut microbiome and its metabolic functions, which highlights the potential role of the gut microbiome in Mn(2+) toxicity, particularly its sex-specific toxic effects. Copyright © 2017 Elsevier Inc. All rights reserved.

  3. [Oxidative stress and autophagy in SK-N-SH cells induced by manganese chloride or 1-methyl-4-phenylpyridinium: a comparative analysis].

    PubMed

    Liu, W L; Dou, C S; Wang, Y; Zhao, P; Fu, J L; Yao, B Y; Zhou, Z C

    2017-02-20

    Objective: To investigate the effect of manganese chloride (MnCl(2)) or 1-methyl-4-phenylpyridinium (MPP (+)) on oxidative stress and autophagy in human neuroblastomaSK-N-SH cells and the mechanism of the neurotoxicity of manganese. Methods: SK-N-SH cells were treated with MnCl(2) or MPP(+) at doses of 0.062 5, 0.125, 0.25, 0.5, 1.0, and 2.0 mmol/L for 24 hours, and MTT assay was used to measure cell viability. The cells weretreated with MnCl(2) or MPP(+) at doses of 0.125, 0.25, and 0.5 mmol/L for 24 hours, and flow cytometry was used to measure the content of reactive oxygen species (ROS) in cells, a laser scanning confocal microscope was used to observe autophagosome in cells, and Western blot was used to measure the expression of autophagy-related proteins P62 and LC3-II/LC3-I. Results: Compared with the control group, the 0.0625-2.0 mmol/L MnCl(2) and 0.125-2.0 mmol/L MPP (+) treatment groups had significant reductions in the viability of SK-N-SH cells, and the 0.25-2.0 mmol/L MnCl(2) treatment groups had significantly lower viability than the groups treated with the same doses of MPP(+) (all P<0.05) . Compared with the control group, the 0.125-0.25 mmol/L MnCl(2) and 0.125-0.5 mmol/L MPP(+) treatment groups had significant increases in the content of ROS, and the 0.25-0.5 mmol/L MPP(+) treatment groups had significantly higher content of ROS than the groups treated with the same doses of MnCl(2) (all P<0.05) . Compared with the control group, the 0.25-0.5 mmol/L MnCl(2) andMPP(+) treatment groups had significant increases in autophagy-related proteins LC3-II/LC3-I and significant reductions in P62 expression; the 0.125-0.5 mmol/L MPP(+) treatment groups had significantly higher LC3-II/LC3-I than the groups treated with the same doses of MnCl(2), and the 0.125 and 0.25 mmol/L MPP (+) treatment groups had significantly lower P62 expression than the groups treated with the same doses of MnCl(2) (all P<0.05) . Conclusion: Both MnCl(2) and MPP(+) can induce

  4. A laser ablation ICP-MS based method for multiplexed immunoblot analysis: applications to manganese-dependent protein dynamics of photosystem II in barley (Hordeum vulgare L.).

    PubMed

    de Bang, Thomas Christian; Petersen, Jørgen; Pedas, Pai Rosager; Rogowska-Wrzesinska, Adelina; Jensen, Ole Noerregaard; Schjoerring, Jan Kofod; Jensen, Poul Erik; Thelen, Jay J; Husted, Søren

    2015-08-01

    Manganese (Mn) constitutes an essential co-factor in the oxygen-evolving complex of photosystem II (PSII). Consequently, Mn deficiency reduces photosynthetic efficiency and leads to changes in PSII composition. In order to study these changes, multiplexed protein assays are advantageous. Here, we developed a multiplexed antibody-based assay and analysed selected PSII subunits in barley (Hordeum vulgare L.). A selection of antibodies were labelled with specific lanthanides and immunoreacted with thylakoids exposed to Mn deficiency after western blotting. Subsequently, western blot membranes were analysed by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), which allowed selective and relative quantitative analysis via the different lanthanides. The method was evaluated against established liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) methods, based on data-dependent acquisition (DDA) and selected reaction monitoring (SRM). Manganese deficiency resulted in a general decrease in PSII protein abundances, an effect that was shown to be reversible upon Mn re-supplementation. Specifically, the extrinsic proteins PsbP and PsbQ showed Mn-dependent changes in abundances. Similar trends in the response to Mn deficiency at the protein level were observed when comparing DDA, SRM and LA-ICP-MS results. A biologically important exception to this trend was the loss of PsbO in the SRM analysis, which highlights the necessity of validating protein changes by more than one technique. The developed method enables a higher number of proteins to be multiplexed in comparison to existing immunoassays. Furthermore, multiplexed protein analysis by LA-ICP-MS provides an analytical platform with high throughput appropriate for screening large collections of plants.

  5. Mechanisms of Mn(II) catalytic oxidation on ferrihydrite surfaces and the formation of manganese (oxyhydr)oxides

    NASA Astrophysics Data System (ADS)

    Lan, Shuai; Wang, Xiaoming; Xiang, Quanjun; Yin, Hui; Tan, Wenfeng; Qiu, Guohong; Liu, Fan; Zhang, Jing; Feng, Xionghan

    2017-08-01

    Oxidation of Mn(II) is an important process that controls the mobility and bioavailability of Mn, as well as the formation of Mn (oxyhydr)oxides in natural systems. It was found that the surfaces of minerals, such as iron (oxyhydr)oxides, can accelerate Mn(II) oxidation to a certain degree, but the underlying mechanism has not been clearly understood. This study explores the reaction pathways and mechanisms of Mn(II) oxidation on ferrihydrite surfaces at neutral pH, commonly found in natural environments, by comparisons with montmorillonite, amorphous Al(OH)3, goethite, and magnetite using macroscopic experiments and spectroscopic analyses. Results show that when Mn(II) concentrations are below 4 mM, macroscopic Mn(II) adsorption on the three iron (oxyhydr)oxide surfaces conforms well to the Langmuir equation, with ferrihydrite showing the highest adsorption capacity. With Mn(II) concentrations ranging within 6-24 mM, the adsorbed Mn(II) is mainly oxidized into manganite (γ-MnOOH) and/or feitknechtite (β-MnOOH) by dissolved O2, and Mn(II) removal on a unit mass basis in the presence of magnetite is the highest compared with ferrihydrite and goethite. Ferrihydrite, a semiconductor material, shows stronger catalytic ability for Mn(II) oxidation on the same surface area than insulator minerals (i.e., montmorillonite and amorphous Al(OH)3). Additionally, the products of Mn(II) oxidation in the presence of semiconductor iron (oxyhydr)oxides (i.e., ferrihydrite, goethite, or magnetite) at the same Fe/Mn molar ratio include both manganite and a small amount of Mn(IV) minerals, and the Mn average oxidation states (Mn AOSs) of these products follow the order: magnetite > goethite > ferrihydrite. Magnetite and goethite, with relatively smaller SSAs and lower band gap energies, exhibit greater catalysis for Mn(II) oxidation than ferrihydrite at the same Fe/Mn ratio, which goes against the conventional interfacial effect and is related to the electrochemical properties. Thus

  6. Overexpression of manganese superoxide dismutase ameliorates high-fat diet-induced insulin resistance in rat skeletal muscle.

    PubMed

    Boden, Michael J; Brandon, Amanda E; Tid-Ang, Jennifer D; Preston, Elaine; Wilks, Donna; Stuart, Ella; Cleasby, Mark E; Turner, Nigel; Cooney, Gregory J; Kraegen, Edward W

    2012-09-15

    Elevated mitochondrial reactive oxygen species have been suggested to play a causative role in some forms of muscle insulin resistance. However, the extent of their involvement in the development of diet-induced insulin resistance remains unclear. To investigate, manganese superoxide dismutase (MnSOD), a key mitochondrial-specific enzyme with antioxidant modality, was overexpressed, and the effect on in vivo muscle insulin resistance induced by a high-fat (HF) diet in rats was evaluated. Male Wistar rats were maintained on chow or HF diet. After 3 wk, in vivo electroporation (IVE) of MnSOD expression and empty vectors was undertaken in right and left tibialis cranialis (TC) muscles, respectively. After one more week, insulin action was evaluated using hyperinsulinemic euglycemic clamp, and tissues were subsequently analyzed for antioxidant enzyme capacity and markers of oxidative stress. MnSOD mRNA was overexpressed 4.5-fold, and protein levels were increased by 70%, with protein detected primarily in the mitochondrial fraction of muscle fibers. This was associated with elevated MnSOD and glutathione peroxidase activity, indicating that the overexpressed MnSOD was functionally active. The HF diet significantly reduced whole body and TC muscle insulin action, whereas overexpression of MnSOD in HF diet animals ameliorated this reduction in TC muscle glucose uptake by 50% (P < 0.05). Decreased protein carbonylation was seen in MnSOD overexpressing TC muscle in HF-treated animals (20% vs. contralateral control leg, P < 0.05), suggesting that this effect was mediated through an altered redox state. Thus interventions causing elevation of mitochondrial antioxidant activity may offer protection against diet-induced insulin resistance in skeletal muscle.

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

    PubMed Central

    2016-01-01

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

  8. Adipocyte-Specific Deletion of Manganese Superoxide Dismutase Protects From Diet-Induced Obesity Through Increased Mitochondrial Uncoupling and Biogenesis.

    PubMed

    Han, Yong Hwan; Buffolo, Márcio; Pires, Karla Maria; Pei, Shaobo; Scherer, Philipp E; Boudina, Sihem

    2016-09-01

    Obesity and insulin resistance are associated with oxidative stress (OS). The causal role of adipose OS in the pathogenesis of these conditions is unknown. To address this issue, we generated mice with an adipocyte-selective deletion of manganese superoxide dismutase (MnSOD). When fed a high-fat diet (HFD), the AdSod2 knockout (KO) mice exhibited less adiposity, reduced adipocyte hypertrophy, and decreased circulating leptin. The resistance to diet-induced adiposity was the result of an increased metabolic rate and energy expenditure. Furthermore, palmitate oxidation was elevated in the white adipose tissue (WAT) and brown adipose tissue of AdSod2 KO mice fed an HFD, and the expression of key fatty acid oxidation genes was increased. To gain mechanistic insight into the increased fat oxidation in HFD-fed AdSod2 KO mice, we quantified the mitochondrial function and mitochondrial content in WAT and found that MnSOD deletion increased mitochondrial oxygen consumption and induced mitochondrial biogenesis. This effect was preserved in cultured adipocytes from AdSod2 KO mice in vitro. As expected from the enhanced fat oxidation, circulating levels of free fatty acids were reduced in the HFD-fed AdSod2 KO mice. Finally, HFD-fed AdSod2 KO mice were protected from hepatic steatosis, adipose tissue inflammation, and glucose and insulin intolerance. Taken together, these results demonstrate that MnSOD deletion in adipocytes triggered an adaptive stress response that activated mitochondrial biogenesis and enhanced mitochondrial fatty acid oxidation, thereby preventing diet-induced obesity and insulin resistance. © 2016 by the American Diabetes Association.

  9. Manganese mineral formation by bacterial spores of the marine Bacillus , strain SG-1: Evidence for the direct oxidation of Mn(II) to Mn(IV)

    NASA Astrophysics Data System (ADS)

    Mandernack, Kevin W.; Post, Jeffrey; Tebo, Bradley M.

    1995-11-01

    The spores of a marine Bacillus bacterium, strain SG-1, are able to oxidize Mn (H) over a wide range of temperatures (0-80°C) and Mn (II) concentrations (25 mM), in both low ionic strength N- (2-hydroxyethyl) piperazine- N'-ethanesulfonic acid (HEPES) buffer (HB) and in HEPES-buffered seawater (SW). Using SG-1 spores as a catalyst for manganese mineral formation, and by varying the temperature and Mn (II) concentration at pH 7.4-8.0, a variety of manganese oxide and manganate minerals were formed under environmentally relevant conditions in HB and SW. In general, mixed phases of lower valence state minerals (hausmannite, Mn 30 4; feitknechtite, βMnOOH; and manganite, γMnOOH) formed in HB and SW at high Mn (II) concentrations (10 mM initial), or at high temperatures (70°C), by two weeks. βMnOOH was favored at low temperatures (3°C) and Mn 3O 4 at higher temperatures (55-70°C). After 1 year of aging, yMnOOH became the dominant or only mineral present at 25 and 55°C. At lower Mn (II) concentrations (initial concentrations ≤100 μM in HB and ≤1 MM in SW), Mn(IV) minerals precipitated. In HB the Mn(IV) minerals most often resembled sodium buserite, evidenced by collapse of a 10 to 7 Å phase with air drying at room temperature. In SW both buserite and Mg-rich noncollapsible 10 Å manganates were formed. The Mg-rich 10 Å manganates did not collapse to 7 Å even with baking at 100°C. The oxidation state of the minerals were generally higher in SW (as high as 3.7) than in HB (3.2). Mn (IV) minerals also formed at higher Mn (II) concentrations in SW than in HB. These observed differences between SW and HB may have resulted from differences in the chemical milieu, or because of the marine adapted physiology of the bacterial spores. Under a variety of conditions (HB and SW, 3-55δC) Mn (IV) mineral formation often occurred at pH and Mn (II) concentrations too high to be favorable for the disproportionation of Mn 30 4, or βMnOOH to Mn (IV). The results

  10. Thermodynamics of electron transfer in oxygenic photosynthetic reaction centers: volume change, enthalpy, and entropy of electron-transfer reactions in manganese-depleted photosystem II core complexes.

    PubMed

    Hou, J M; Boichenko, V A; Diner, B A; Mauzerall, D

    2001-06-19

    We have previously reported the thermodynamic data of electron transfer in photosystem I using pulsed time-resolved photoacoustics [Hou et al. (2001) Biochemistry 40, 7109-7116]. In the present work, using preparations of purified manganese-depleted photosystem II (PS II) core complexes from Synechocystis sp. PCC 6803, we have measured the DeltaV, DeltaH, and estimated TDeltaS of electron transfer on the time scale of 1 micros. At pH 6.0, the volume contraction of PS II was determined to be -9 +/- 1 A3. The thermal efficiency was found to be 52 +/- 5%, which corresponds to an enthalpy change of -0.9 +/- 0.1 eV for the formation of the state P680+Q(A-) from P680*. An unexpected volume expansion on pulse saturation of PS II was observed, which is reversible in the dark. At pH 9.0, the volume contraction, the thermal efficiency, and the enthalpy change were -3.4 +/- 0.5 A3, 37 +/- 7%, and -1.15 +/- 0.13 eV, respectively. The DeltaV of PS II, smaller than that of PS I and bacterial centers, is assigned to electrostriction and analyzed using the Drude-Nernst equation. To explain the small DeltaV for the formation of P680+Q(A-) or Y(Z*)Q(A-), we propose that fast proton transfer into a polar region is involved in this reaction. Taking the free energy of charge separation of PS II as the difference between the energy of the excited-state P680* and the difference in the redox potentials of the donor and acceptor, the apparent entropy change (TDeltaS) for charge separation of PS II is calculated to be negative, -0.1 +/- 0.1 eV at pH 6.0 (P680+Q(A-)) and -0.2 +/- 0.15 eV at pH 9.0 (Y(Z*)Q(A-)). The thermodynamic properties of electron transfer in PS II core reaction centers thus differ considerably from those of bacterial and PS I reaction centers, which have DeltaV of approximately -27 A3, DeltaH of approximately -0.4 eV, and TDeltaS of approximately +0.4 eV.

  11. Phosphorus(V) Porphyrin-Manganese(II) Terpyridine Conjugates: Synthesis, Spectroscopy, and Photo-Oxidation Studies on a SnO2 Surface.

    PubMed

    Poddutoori, Prashanth K; Lim, Gary N; Pilkington, Melanie; D'Souza, Francis; van der Est, Art

    2016-11-07

    A major challenge in designing artificial photosynthetic systems is to find a suitable mimic of the highly oxidizing photoactive species P680 in photosystem II. High-potential phosphorus(V) porphyrins have many attractive properties for such a mimic but have not been widely studied. Here, we report the synthesis and photophysical characterization of a novel phosphorus(V) octaethylporphyrin-oxyphenyl-terpyridine conjugate (PPor-OPh-tpy, 1) and its corresponding manganese(II) complex (PPor-OPh-Mn(tpy)Cl2, 2). The X-ray structure of 2 shows that the Mn(II) and P(V) centers are 11.783 Å apart and that the phenoxy linker is not fully conjugated with the terpyridine ligand. The porphyrin fluorescence in 1 and 2 is strongly quenched and has a shorter lifetime compared to a reference compound without the terpyridine ligand. This suggests that electron transfer from tpy or Mn(tpy) to the excited singlet state of the PPor may be occurring. However, femtosecond transient absorbance data show that the rate of relaxation to the ground state in 1 and 2 is comparable to the fluorescence lifetimes. Thus, if charge separation is occurring, its lifetime is short. Because both 1 and 2 are positively charged, they can be electrostatically deposited onto the surface of negatively charged SnO2 nanoparticles. Freeze-trapping EPR studies of 2 electrostatically bound to SnO2 suggest that excitation of the porphyrin results in electron injection from (1)PPor* into the conduction band of SnO2 and that the resulting PPor(•+) species acquires enough potential to photo-oxidize the axially bound Mn(II) (tpy) moiety to Mn(III) (tpy).

  12. A new aqua­manganese(II) oxalate phosphate, Mn(C2O4)Mn3(PO4)2(H2O)2

    PubMed Central

    Zheng, Juan; Shen, Yuxia; Song, Tao; Zhang, Aiyun

    2009-01-01

    The title salt, diaquatetra­manganese(II) oxalate bis[ortho­phos­phate(V)], Mn4(C2O4)(PO4)2(H2O)2, was synthesized hydro­thermally and displays a three-dimensional framework structure. The asymmetric unit consists of two different MnII centers, half of an oxalate anion, a phosphate group and a coordinated water mol­ecule. A crystallographic inversion center is located at the mid-point of the oxalate C—C bond. The distorted octa­hedral MnO6 and the tetra­gonal pyramidal MnO5 centers are linked through bridging oxalate and phosphate groups. The water mol­ecule also has a weaker bonding contact to the five-coordinate Mn atom, which consequently exhibits a distorted octa­hedral geometry and also bridges the independent Mn atoms. The water mol­ecule is a donor for intra- and inter­molecular O—H⋯O hydrogen bonds. PMID:21583724

  13. Inorganic particulates in removal of heavy metal toxic ions IX. Rapid and efficient removal of Hg(II) by hydrous manganese and tin oxides.

    PubMed

    Mishra, Shuddhodan P; Dubey, Som Shankar; Tiwari, Diwakar

    2004-11-01

    Batch studies have been carried out in the removal of Hg(II) from aqueous solutions by using well-synthesized and -characterized hydrous manganese oxide (HMO) and hydrous tin oxide (HTO) employing a radiotracer technique. Results obtained reveal that increased sorptive concentration (10(-8)-10(-2) mol dm(-3)), temperature (298-328 K), and pH (ca. 2.0-10.5) enhance the removal efficiency of these solids. First-order uptake of Hg(II) on HMO and HTO follows the Freundlich adsorption isotherm for entire concentration range. Positive values of DeltaH0 for the uptake process on both solids indicate endothermic uptake and desorption experiments point to irreversible uptake. Radiation stability of the adsorbents has also been assessed using a 300-mCi (Ra-Be) neutron source having an integral neutron flux of 3.85 x 10(6) N cm(-2) s(-1) and associated with a nominal gamma-dose of ca. 1.72 Gy/h.

  14. Effects of mimic of manganese superoxide dismutase on 2,4,6-trinitrobenzene sulfonic acid-induced colitis in rats.

    PubMed

    Wang, Yan-Hong; Dong, Jiao; Zhang, Jian-Xin; Zhai, Jing; Ge, Bin

    2016-09-01

    The mimic of manganese superoxide dismutase (MnSODm) has been synthesized and reported to have anti-inflammatory properties. However, whether MnSODm has anti-inflammatory effects on colitis and any underlying mechanisms are poorly understood. This study was to investigate therapeutic effects and mechanism of MnSODm on 2,4,6-trinitrobenzenesulfonic acid (TNBS) induced colitis model in rats. Rats were intragastrically administered MnSODm (10, 20, and 40 mg/kg) per day for 7 days after colitis was induced by TNBS. After treated with MnSODm, the colonic macroscopic and microscopic damage scores and colonic weight/length ratios were significantly decreased compared with colitis model group. Myeloperoxidase (MPO) activity, malonyldialdehyde (MDA), tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, IL-6, and IL-8 levels in colon tissues were also significantly decreased in MnSODm treatment groups. However, superoxide dismutase (SOD) activity significantly increased and phosphorylated inhibitory kappa B-alpha (IκBα), inhibitor kappa B kinase (IKKα/β), and nuclear factor-kappa Bp65 (NF-κBp65) as well as Toll-like receptor 4 (TLR4) and myeloid differentiation actor 88 (MyD88) in the colonic mucosa were significantly inhibited by MnSODm treatment. Thus, MnSODm was protective against colitis via antioxidant activity and by inhibiting inflammatory mediators by down-regulating TLR4/MyD88/NF-κB signaling pathways. These data suggest a potential therapeutic effect of MnSODm in colitis.

  15. Combined effect of demagnetizing field and induced magnetic anisotropy on the magnetic properties of manganese-zinc ferrite composites

    NASA Astrophysics Data System (ADS)

    Babayan, V.; Kazantseva, N. E.; Moučka, R.; Sapurina, I.; Spivak, Yu. M.; Moshnikov, V. A.

    2012-01-01

    This work is devoted to the analysis of factors responsible for the high-frequency shift of the complex permeability (μ*) dispersion region in polymer composites of manganese-zinc (MnZn) ferrite, as well as to the increase in their thermomagnetic stability. The magnetic spectra of the ferrite and its composites with polyurethane (MnZn-PU) and polyaniline (MnZn-PANI) are measured in the frequency range from 1 MHz to 3 GHz in a longitudinal magnetization field of up to 700 Ое and in the temperature interval from -20 °С to +150 °С. The approximation of the magnetic spectra by a model, which takes into account the role of domain wall motion and magnetization rotation, allows one to determine the specific contribution of resonance processes associated with domain wall motion and the natural ferromagnetic resonance to the μ*. It is established that, at high frequencies, the μ* of the MnZn ferrite is determined solely by magnetization rotation, which occurs in the region of natural ferromagnetic resonance when the ferrite is in the “single domain” state. In the polymer composites of the MnZn ferrite, the high-frequency permeability is also determined mainly by the magnetization rotation; however, up to high values of magnetizing fields, there is a contribution of domain wall motion, thus the “single domain” state in ferrite is not reached. The frequency and temperature dependence of μ* in polymer composites are governed by demagnetizing field and the induced magnetic anisotropy. The contribution of the induced magnetic anisotropy is crucial for MnZn-PANI. It is attributed to the elastic stresses that arise due to the domain wall pinning by a polyaniline film adsorbed on the surface of the ferrite during in-situ polymerization.

  16. α-Synuclein is involved in manganese-induced ER stress via PERK signal pathway in organotypic brain slice cultures.

    PubMed

    Xu, Bin; Wang, Fei; Wu, Sheng-Wen; Deng, Yu; Liu, Wei; Feng, Shu; Yang, Tian-Yao; Xu, Zhao-Fa

    2014-02-01

    Overexposure to manganese (Mn) has been known to induce neuronal damage involving endoplasmic reticulum (ER) stress. However, the exact mechanism of Mn-induced ER stress is unclear. Increasing evidence suggested that the overexpression of alpha-synuclein played a critical role in Mn-induced neurotoxicity. To explore whether the occurrence of ER stress was associated with alpha-synuclein overexpression, we made the rat brain slices model of silencing alpha-synuclein using short-interference RNA. After non-silencing alpha-synuclein slices were treated with Mn (0-400 μM) for 24 h, there was a dose-dependent increase in apoptotic rates of cells and levels of lactate dehydrogenase in the culture medium. Moreover, there was a dose-dependent increase in the protein expression of 78, 94-kDa glucose-regulated protein (GRP78/94), C/EBP homologous protein (CHOP), and caspase-12. Moreover, PKR-like ER kinase (PERK) phosphorylation, PERK-mediated phosphorylation of eIF2a, and ATF4 expression also increased. Inositol-requiring enzyme 1 (IRE1) activation and X-box-binding protein-1 (Xbp1) mRNA splicing increased. Activating transcription factor 6 p90 levels did not change. However, after silencing alpha-synuclein slices were treated with 400 μM Mn for 24 h, there was a significant decrease in the expression of GRP78/94, CHOP, and caspase-12 compared with 400 μM Mn-treated non-silencing alpha-synuclein slices. Furthermore, PERK phosphorylation, PERK-mediated phosphorylation of eIF2a, and ATF4 mRNA expression also decreased. However, IRE1 phosphorylation and Xbp1 mRNA splicing did not change. The findings revealed that Mn induced ER stress via activation of PERK and IRE1 signaling pathways and subsequent apoptosis in cultured slices. Moreover, alpha-synuclein protein was associated with Mn-induced activation of PERK signaling pathway.

  17. pH optimum of the photosystem II H₂O oxidation reaction: effects of PsbO, the manganese-stabilizing protein, Cl- retention, and deprotonation of a component required for O₂ evolution activity.

    PubMed

    Commet, Alan; Boswell, Nicholas; Yocum, Charles F; Popelka, Hana

    2012-05-08

    Hydroxide ion inhibits Photosystem II (PSII) activity by extracting Cl(-) from its binding site in the O(2)-evolving complex (OEC) under continuous illumination [Critchley, C., et al. (1982) Biochim. Biophys. Acta 682, 436]. The experiments reported here examine whether two subunits of PsbO, the manganese-stabilizing protein, bound to eukaryotic PSII play a role in protecting the OEC against OH(-) inhibition. The data show that the PSII binding properties of PsbO affect the pH optimum for O(2) evolution activity as well as the Cl(-) affinity of the OEC that decreases with an increasing pH. These results suggest that PsbO functions as a barrier against inhibition of the OEC by OH(-). Through facilitation of efficient retention of Cl(-) in PSII [Popelkova, H., et al. (2008) Biochemistry 47, 12593], PsbO influences the ability of Cl(-) to resist OH(-)-induced release from its site in the OEC. Preventing inhibition by OH(-) allows for normal (short) lifetimes of the S(2) and S(3) states in darkness [Roose, J. L., et al. (2011) Biochemistry 50, 5988] and for maximal steady-state activity by PSII. The data presented here indicate that activation of H(2)O oxidation occurs with a pK(a) of ∼6.5, which could be a function of deprotonation of one or more amino acid residues that reside near the OEC active site on the D1 and CP43 intrinsic subunits of the PSII reaction center.

  18. The design of synthetic superoxide dismutase mimetics: seven-coordinate water soluble manganese(ii) and iron(ii) complexes and their superoxide dismutase-like activity studies.

    PubMed

    Singh, Ovender; Tyagi, Nidhi; Olmstead, Marilyn M; Ghosh, Kaushik

    2017-10-06

    Bio-inspired manganese [Mn(N5Py)(H2O)(CH3OH)](ClO4)2 (1) and iron [Fe(N5Py)(H2O)(ClO4)]ClO4 (2) complexes derived from a pentadentate ligand (N5Py = 2,6-bis((E)-1-phenyl-2-(pyridin-2-ylmethylene)hydrazinyl)pyridine) framework containing a N5 binding motif were synthesized and characterized using different spectroscopic methods. The molecular structures of complexes 1 and 2 were determined by X-ray crystallography. These complexes were found to be stable under physiological conditions and exhibited an excellent superoxide dismutase (SOD) activity. The SOD activity was determined by a xanthine-xanthine oxidase-nitro blue tetrazolium assay and the IC50 values were determined to be 1.53 and 2.09 μM, respectively.

  19. pH-Dependent solution dynamics of a manganese(II) polyoxometalate, [Mn4(H2O)2(P2W15O56)2](16-), and [Mn(H2O)6](2+).

    PubMed

    Sharma, Rupali; Zhang, Jie; Ohlin, C André

    2015-11-28

    The aqueous reaction dynamics of the manganese(II)-functionalised Wells-Dawson polyoxometalate [Mn4(H2O)2(P2W15O56)2](16-) has been determined as a function of pH using variable temperature (17)O NMR, and compared with that of the well-studied monomeric manganese(II) hexa-aqua ion, [Mn(H2O)6](2+). While the rate of aquo-ligand exchange on the hexa-aqua ion remains independent of pH in the range 3.2-6.0, the rate of water exchange of the polyoxometalate ion varies by a factor of fifteen, from 1.98 × 10(7) s(-1) at pH 3.2 to 1.3 × 10(6) s(-1) at pH 6.0. This decrease in the rate of exchange correlates with the deprotonation of the polyoxometalate framework.

  20. Binding of manganese(II) to a tertiary stabilized hammerhead ribozyme as studied by electron paramagnetic resonance spectroscopy

    PubMed Central

    KISSELEVA, NATALIA; KHVOROVA, ANASTASIA; WESTHOF, ERIC; SCHIEMANN, OLAV

    2005-01-01

    Electron paramagnetic resonance (EPR) spectroscopy is used to study the binding of MnII ions to a tertiary stabilized hammer-head ribozyme (tsHHRz) and to compare it with the binding to the minimal hammerhead ribozyme (mHHRz). Continuous wave EPR measurements show that the tsHHRz possesses a single high-affinity MnII binding site with a KD of ≤10 nM at an NaCl concentration of 0.1 M. This dissociation constant is at least two orders of magnitude smaller than the KD determined previously for the single high-affinity MnII site in the mHHRz. In addition, whereas the high-affinity MnII is displaced from the mHHRz upon binding of the aminoglycoside antibiotic neomycin B, it is not from the tsHHRz. Despite these pronounced differences in binding, a comparison between the electron spin echo envelope modulation and hyperfine sublevel correlation spectra of the minimal and tertiary stabilized HHRz demonstrates that the structure of both binding sites is very similar. This suggests that the MnII is located in both ribozymes between the bases A9 and G10.1 of the sheared G · A tandem base pair, as shown previously and in detail for the mHHRz. Thus, the much stronger MnII binding in the tsHHRz is attributed to the interaction between the two external loops, which locks in the RNA fold, trapping the MnII in the tightly bound conformation, whereas the absence of long-range loop–loop interactions in the mHHRz leads to more dynamical and open conformations, decreasing MnII binding. PMID:15611296

  1. Structure, antimicrobial activity, DNA- and albumin-binding of manganese(II) complexes with the quinolone antimicrobial agents oxolinic acid and enrofloxacin.

    PubMed

    Zampakou, Marianthi; Akrivou, Melpomeni; Andreadou, Eleni G; Raptopoulou, Catherine P; Psycharis, Vassilis; Pantazaki, Anastasia A; Psomas, George

    2013-04-01

    The reaction of MnCl2 with the quinolone antibacterial drug oxolinic acid (Hoxo) results to the formation of [KMn(oxo)3(MeOH)3]. Interaction of MnCl2 with the quinolone Hoxo or enrofloxacin (Herx) and the N,N'-donor heterocyclic ligand 1,10-phenanthroline (phen) results in the formation of metal complexes with the general formula [Mn(quinolonato)2(phen)]. The crystal structures of [KMn(oxo)3(MeOH)3] and [Mn(erx)2(phen)], exhibiting a 1D polymeric and a mononuclear structure, respectively, have been determined by X-ray crystallography. In these complexes, the deprotonated bidentate quinolonato ligands are coordinated to manganese(II) ion through the pyridone oxygen and a carboxylato oxygen. All complexes can act as potential antibacterial agents with [Mn(erx)2(phen)] exhibiting the most pronounced antimicrobial activity against five different microorganisms. Interaction of the complexes with calf-thymus DNA (CT DNA), studied by UV spectroscopy, has shown that they bind to CT DNA. Competitive study with ethidium bromide (EB) has shown that all complexes can displace the DNA-bound EB indicating their binding to DNA in strong competition with EB. Intercalative binding mode is proposed for the interaction of the complexes with CT DNA and has also been verified by DNA solution viscosity measurements and cyclic voltammetry. DNA electrophoretic mobility experiments suggest that [Mn(erx)2(phen)] binds strongly to supercoiled pDNA and to linearized pDNA possibly by an intercalative manner provoking double-stranded cleavage reflecting in a nuclease-like activity. The complexes exhibit good binding propensity to human or bovine serum albumin protein showing relatively high binding constant values. The binding constants of the complexes towards CT DNA and albumins have been compared to their corresponding zinc(II) and nickel(II) complexes.

  2. The effects of iron(II) on the kinetics of arsenic oxidation and sorption on manganese oxides.

    PubMed

    Wu, Yun; Li, Wei; Sparks, Donald L

    2015-11-01

    In this study, As(III) oxidation kinetics by a poorly-crystalline phyllomanganate (δ-MnO2) in the presence and absence of dissolved Fe(II) was investigated using stirred-flow and batch experiments. Chemically synthetic δ-MnO2 was reacted with four influent solutions, containing the same As(III) concentration but different Fe(II) concentrations, at pH 6. The results show an initial rapid As(III) oxidation by δ-MnO2, which is followed by an appreciably slow reaction after 8h. In the presence of Fe(II), As(III) oxidation is inhibited due to the competitive oxidation of Fe(II) as well as the formation of Fe(III)-(hydr)oxides on the δ-MnO2 surface. However, the sorption of As(III), As(V) and Mn(II) are increased, for the newly formed Fe(III)-(hydr)oxides provide additional sorption sites. This study suggests that the competitive oxidation of Fe(II) and consequently the precipitation of Fe(III) compounds on the δ-MnO2 surface play an important role in As(III) oxidation and As sequestration. Understanding these processes would be helpful in developing in situ strategies for remediation of As-contaminated waters and soils.

  3. Novel EGFR inhibitors attenuate cardiac hypertrophy induced by angiotensin II.

    PubMed

    Peng, Kesong; Tian, Xinqiao; Qian, Yuanyuan; Skibba, Melissa; Zou, Chunpeng; Liu, Zhiguo; Wang, Jingying; Xu, Zheng; Li, Xiaokun; Liang, Guang

    2016-03-01

    Cardiac hypertrophy is an important risk factor for heart failure. Epidermal growth factor receptor (EGFR) has been found to play a role in the pathogenesis of various cardiovascular diseases. The aim of this current study was to examine the role of EGFR in angiotensin II (Ang II)-induced cardiac hypertrophy and identify the underlying molecular mechanisms. In this study, we observed that both Ang II and EGF could increase the phospohorylation of EGFR and protein kinase B (AKT)/extracellular signal-regulated kinase (ERK), and then induce cell hypertrophy in H9c2 cells. Both pharmacological inhibitors and genetic silencing significantly reduced Ang II-induced EGFR signalling pathway activation, hypertrophic marker overexpression, and cell hypertrophy. In addition, our results showed that Ang II-induced EGFR activation is mediated by c-Src phosphorylation. In vivo, Ang II treatment significantly led to cardiac remodelling including cardiac hypertrophy, disorganization and fibrosis, accompanied by the activation of EGFR signalling pathway in the heart tissues, while all these molecular and pathological alterations were attenuated by the oral administration with EGFR inhibitors. In conclusion, the c-Src-dependent EGFR activation may play an important role in Ang II-induced cardiac hypertrophy, and inhibition of EGFR by specific molecules may be an effective strategy for the treatment of Ang II-associated cardiac diseases. © 2016 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.

  4. MECHANISMS OF MANGANESE-INDUCED RAT PHEOCHROMOCYTOMA (PC12) CELL DEATH AND CELL DIFFERENTIATION. (R826248)

    EPA Science Inventory

    Mn is a neurotoxin that leads to a syndrome resembling Parkinson's disease after prolonged exposure to high concentrations. Our laboratory has been investigating the mechanism by which Mn induces neuronal cell death. To accomplish this, we have utilized rat pheochromocytom...

  5. MECHANISMS OF MANGANESE-INDUCED RAT PHEOCHROMOCYTOMA (PC12) CELL DEATH AND CELL DIFFERENTIATION. (R826248)

    EPA Science Inventory

    Mn is a neurotoxin that leads to a syndrome resembling Parkinson's disease after prolonged exposure to high concentrations. Our laboratory has been investigating the mechanism by which Mn induces neuronal cell death. To accomplish this, we have utilized rat pheochromocytom...

  6. Biological low pH Mn(II) oxidation in a manganese deposit influenced by metal-rich groundwater

    USGS Publications Warehouse

    Bohu, Tsing; Akob, Denise M.; Abratis, Michael; Lazar, Cassandre S.; Küsel, Kirsten

    2016-01-01

    The mechanisms, key organisms, and geochemical significance of biological low-pH Mn(II) oxidation are largely unexplored. Here, we investigated the structure of indigenous Mn(II)-oxidizing microbial communities in a secondary subsurface Mn oxide deposit influenced by acidic (pH 4.8) metal-rich groundwater in a former uranium mining area. Microbial diversity was highest in the Mn deposit compared to the adjacent soil layers and included the majority of known Mn(II)-oxidizing bacteria (MOB) and two genera of known Mn(II)-oxidizing fungi (MOF). Electron X-ray microanalysis showed that romanechite [(Ba,H2O)2(Mn4+,Mn3+)5O10] was conspicuously enriched in the deposit. Canonical correspondence analysis revealed that certain fungal, bacterial, and archaeal groups were firmly associated with the autochthonous Mn oxides. Eight MOB within the Proteobacteria, Actinobacteria, and Bacteroidetes and one MOF strain belonging to Ascomycota were isolated at pH 5.5 or 7.2 from the acidic Mn deposit. Soil-groundwater microcosms demonstrated 2.5-fold-faster Mn(II) depletion in the Mn deposit than adjacent soil layers. No depletion was observed in the abiotic controls, suggesting that biological contribution is the main driver for Mn(II) oxidation at low pH. The composition and species specificity of the native low-pH Mn(II) oxidizers were highly adapted to in situ conditions, and these organisms may play a central role in the fundamental biogeochemical processes (e.g., metal natural attenuation) occurring in the acidic, oligotrophic, and metalliferous subsoil ecosystems.

  7. Complex pathologies of angiotensin II-induced abdominal aortic aneurysms*

    PubMed Central

    Daugherty, Alan; Cassis, Lisa A.; Lu, Hong

    2011-01-01

    Angiotensin II (AngII) is the primary bioactive peptide of the renin angiotensin system that plays a critical role in many cardiovascular diseases. Subcutaneous infusion of AngII into mice induces the development of abdominal aortic aneurysms (AAAs). Like human AAAs, AngII-induced AAA tissues exhibit progressive changes and considerable heterogeneity. This complex pathology provides an impediment to the quantification of aneurysmal tissue composition by biochemical and immunostaining techniques. Therefore, while the mouse model of AngII-induced AAAs provides a salutary approach to studying the mechanisms of the evolution of AAAs in humans, meaningful interpretation of mechanisms requires consideration of the heterogeneous nature of the diseased tissue. PMID:21796801

  8. Exchange of chloride by bromide in the manganese photosystem-II complex studied by cw- and pulsed-EPR

    NASA Astrophysics Data System (ADS)

    Boussac, Alain

    1995-05-01

    Cl - is an essential cofactor in Photosystem-II (PS-II) oxygen evolution. By using electron spin echo envelope spectroscopy it is shown that, in some circumstances, magnetic couplings between the Mn cluster, in the S 2-state, and those of the observed. In order to extract only the electron nuclear couplings between the Mn cluster, in the S 2-state, and those of the halide, a comparison was done between chloride- and bromide-reconstituted samples. In salt-washed, CaCl 2- or CaBr 2-reconstituted Photosystem-II membranes, frequencies similar to the Larmor frequency of bromide and chloride were detected. When Cl - and Br - reconstituted PS-II membranes are compared to membranes that have also been Ca 2+-depleted, and EGTA-treated, these features in the frequency spectra are absent. After chloride depletion at high pH in the presence of sulfate, no difference could be observed in the frequency spectra of bromide- and chloride-reconstituted samples. These results are discussed in view of possible different Cl - binding sites in PS-II.

  9. Moderate hypoxia is able to minimize the manganese-induced toxicity in tissues of silver catfish (Rhamdia quelen).

    PubMed

    Dolci, G S; Dias, V T; Roversi, K; Roversi, Kr; Pase, C S; Segat, H J; Teixeira, A M; Benvegnú, D M; Trevizol, F; Barcelos, R C S; Riffel, A P K; Nunes, M A G; Dressler, V L; Flores, E M M; Baldisserotto, B; Bürger, M E

    2013-05-01

    The aim of this study was to compare the effects of manganese (Mn) on silver catfish exposed to different levels of dissolved oxygen. Silver catfish (Rhamdia quelen) were exposed to increasing concentrations of Mn (4.2, 8.4 or 16.2mgL(-1)) under either normoxia (100 percent saturation) or moderate hypoxia (51.87 percent saturation) for 15 days. Under normoxia, Mn exposure increased lipid peroxidation (LP) in brain and kidney; it increased gluthatione (GSH) levels in brain and decreased catalase (CAT) activity in both tissues. Moderate hypoxia was able to prevent Mn-induced LP in brain and to reduce this oxidative parameter in kidney; GSH level was increased in brain, while CAT activity was reduced in both tissues. Activity of isolated mitochondria of liver and gills was reduced by Mn exposure under both levels of dissolved oxygen, but this effect was more prominent in normoxia. As expected, liver, kidney and gills showed an increase of Mn accumulation according to waterborne levels, and these parameters presented positive relationship. The highest waterborne Mn (8.4 and 16.2mgL(-1)) resulted in greater accumulation under normoxia, indicating that moderate hypoxia can stimulate mechanisms capable of reducing Mn accumulation in tissues (though not in blood). Moderate hypoxia can be considered a stress factor and Mn an aquatic anthropogenic contaminant. Therefore we hypothesized that these two conditions together are able to invoke defense mechanisms in juvenile silver catfish, acting in a compensatory form, which may be related to adaptation and/or hormesis. Copyright © 2013 Elsevier Inc. All rights reserved.

  10. Effects of manganese, calcium, magnesium and zinc on nickel-induced suppression of murine natural killer cell activity

    SciTech Connect

    Smialowicz, R.J.; Rogers, R.R.; Riddle, M.M.; Luebke, R.W.; Fogelson, L.D.; Rowe, D.G.

    1987-01-01

    The effects that divalent metals have on nickel-induced suppression of natural killer (NK) cell activity were studied in mice. Male CBA/J mice were given a single intramuscular injection of the following: nickel chloride, 4.5-36 ..mu..g/g; manganese chloride, 20-80 ..mu..g/g; magnesium acetate, 50-200 ..mu..g/g; zinc acetate, 2-8 ..mu..g/g; or calcium acetate, 12.5-50 ..mu..g/g. Twenty-four hours after metal injection, splenic NK cell activity was assessed using a /sup 51/Cr-release assay. Ni significantly suppressed NK activity, while Mn significantly enhanced NK activity. No alteration in NK activity was observed in mice injected with Mg, Ca, or Zn. The injection of Ni and Mn in combination at a single site resulted in the enhancement of NK activity, although this enhancement was at a level below that observed following the injection of Mn alone. Injection of Mg, Zn, or Ca in combination with Ni did not affect NK activity compared to saline controls. In contrast, the injection of Ni in one thigh followed immediately by Mn, Mg, Ca, or Zn into the other thigh resulted in significant suppression of NK activity for all metals compared with saline controls. An interesting finding was that the injection of Ni followed immediately by Mn into the opposite thigh resulted in even greater reduction in NK activity than Ni alone. Suppression of NK activity by Ni and Mn injected at separate sites was not seen when Mn injection preceded Ni injection by 1 h.

  11. Quantitative activity-induced manganese-dependent MRI for characterizing cortical layers in the primary somatosensory cortex of the rat.

    PubMed

    Auffret, Matthieu; Samim, Idrees; Lepore, Mario; Gruetter, Rolf; Just, Nathalie

    2016-03-01

    The ability of Mn(2+) to follow Ca(2+) pathways upon stimulation transform them into remarkable surrogate markers of neuronal activity using activity-induced manganese-dependent MRI (AIM-MRI). In the present study, a precise follow-up of physiological parameters during MnCl2 and mannitol infusions improved the reproducibility of AIM-MRI allowing in-depth evaluation of the technique. Pixel-by-pixel T1 data were investigated using histogram distributions in the barrel cortex (BC) and the thalamus before and after Mn(2+) infusion, after blood brain barrier opening and after BC activation. Mean BC T1 values dropped significantly upon trigeminal nerve (TGN) stimulation (-38 %, P = 0.02) in accordance with previous literature findings. T1 histogram distributions showed that 34 % of T1s in the range 600-1500 ms after Mn(2+ )+ mannitol infusions shifted to 50-350 ms after TGN stimulation corresponding to a twofold increase of the percentage of pixels with the lowest T1s in BC. Moreover, T1 changes in response to stimulation increased significantly from superficial cortical layers (I-III) to deeper layers (V-VI). Cortical cytoarchitecture detection during a functional paradigm was performed extending the potential of AIM-MRI. Quantitative AIM-MRI could thus offer a means to interpret local neural activity across cortical layers while identification of the role of calcium dynamics in vivo during brain activation could play a key role in resolving neurovascular coupling mechanisms.

  12. Activity-induced manganese-dependent MRI (AIM-MRI) and functional MRI in awake rabbits during somatosensory stimulation

    PubMed Central

    Schroeder, Matthew P.; Weiss, Craig; Procissi, Daniel; Wang, Lei; Disterhoft, John F.

    2015-01-01

    Activity-induced manganese-dependent MRI (AIM-MRI) is a powerful tool to track system-wide neural activity using high resolution, quantitative T1-weighted MRI in animal models and has significant advantages for investigating neural activity over other modalities including BOLD fMRI. With AIM-MRI, Mn2+ ions enter neurons via voltage-gated calcium channels preferentially active during the time of experimental exposure. A broad range of AIM-MRI studies using different species studying different phenomena have been performed, but few of these studies provide a systematic evaluation of the factors influencing the detection of Mn2+ such as dosage and the temporal characteristics of Mn2+ uptake. We identified an optimal dose of Mn2+ (25 mg/kg, s.c.) in order to characterize the time-course of Mn2+ accumulation in active neural regions in the rabbit. T1-weighted MRI and functional MRI were collected 0–3, 6–9, and 24–27 h post-Mn2+ injection while the vibrissae on the right side were vibrated. Significant BOLD activation in the left somatosensory (SS) cortex and left ventral posteromedial (VPM) thalamic nucleus was detected during whisker vibration. T1-weighted signal intensities were extracted from these regions, their corresponding contralateral regions and the visual cortex (to serve as controls). A significant elevation in T1-weighted signal intensity in the left SS cortex (relative to right)was evident 6–9 and 24–27 h post-Mn2+ injection while the left VPM thalamus showed a significant enhancement (relative to the right) only during the 24–27 h session. Visual cortex showed no hemispheric difference at any timepoint. Our results suggest that studies employing AIM-MRI would benefit by conducting experimental manipulations 6–24 h after subcutaneous MnCl2 injections to optimize the concentration of contrast agent in the regions active during the exposure. PMID:26589332

  13. Post-translational modification of manganese superoxide dismutase in acutely rejecting cardiac transplants: role of inducible nitric oxide synthase.

    PubMed

    Nilakantan, Vani; Halligan, Nadine L N; Nguyen, Thanh K; Hilton, Gail; Khanna, Ashwani K; Roza, Allan M; Johnson, Christopher P; Adams, Mark B; Griffith, Owen W; Pieper, Galen M

    2005-10-01

    Nitration of a critical tyrosine residue in the active site of manganese superoxide dismutase (MnSOD) can lead to enzyme inactivation. In this study, we examined the effect of inducible nitric oxide synthase (iNOS) on MnSOD expression, activity and nitration in acutely rejecting cardiac transplants. Lewis (isograft) or Wistar-Furth (allograft) donor hearts were transplanted into Lewis recipient rats. Some rats received L-N6-(1-iminoethyl) lysine (l-NIL), a specific iNOS inhibitor. Protein nitration was determined by immunohistochemical, Western blot and slot-blot analyses. MnSOD enzyme activity and gene expression were determined using Western, reverse transcriptase-polymerase chain reaction (RT-PCR) and immunoprecipitation techniques. MnSOD protein levels were decreased 50% by post-operative day 6 (POD 6), which was prevented by L-NIL. RT-PCR analysis indicated that this decrease could not be explained by any changes in MnSOD mRNA. MnSOD enzyme activity but not protein was decreased at POD 5 in untreated allografts. The loss of MnSOD activity at POD 5 was also prevented by L-NIL. Immunoreactive nitrotyrosine was apparent in untreated allografts at POD 6. Slot-blot analysis indicated that nitrotyrosine formation in allografts could be blocked by L-NIL. Nitration of MnSOD was evident upon immunoprecipitation of MnSOD followed by Western blotting for nitrotyrosine. These results suggest that the decreased MnSOD enzyme activity in acutely rejecting cardiac allografts can be attributed to a post-translational modification related to nitration arising via an iNOS-dependent pathway. This could be a potential major source of amplified oxidative stress in acute graft rejection.

  14. Ultra-sensitive and selective NH3 room temperature gas sensing induced by manganese-doped titanium dioxide nanoparticles.

    PubMed

    Tshabalala, Zamaswazi P; Shingange, Katekani; Cummings, Franscious R; Ntwaeaborwa, Odireleng M; Mhlongo, Gugu H; Motaung, David E

    2017-10-15

    The study of the fabrication of ultra-high sensitive and selective room temperature ammonia (NH3) and nitrogen dioxide (NO2) gas sensors remains an important scientific challenge in the gas sensing field. This is motivated by their harmful impact on the human health and environment. Therefore, herein, we report for the first time on the gas sensing properties of TiO2 nanoparticles doped with various concentrations of manganese (Mn) (1.0, 1.5, 2.0, 2.5 and 3.0mol.% presented as S1, S2, S3, S4 and S5, respectively), synthesized using hydrothermal method. Structural analyses showed that both undoped and Mn-doped TiO2 crystallized in tetragonal phases. Optical studies revealed that the Mn doped TiO2 nanoparticles have enhanced UV→Vis emission with a broad shoulder at 540nm, signifying induced defects by substituting Ti(4+) ions with Mn(2+). The X-ray photoelectron spectroscopy and the electron paramagnetic resonance studies revealed the presence of Ti(3+) and singly ionized oxygen vacancies in both pure and Mn doped TiO2 nanoparticles. Additionally, a hyperfine split due to Mn(2+) ferromagnetic ordering was observed, confirming incorporation of Mn ions into the lattice sites. The sensitivity, selectivity, operating temperature, and response-recovery times were thoroughly evaluated according to the alteration in the materials electrical resistance in the presence of the target gases. Gas sensing studies showed that Mn(2+) doped on the TiO2 surface improved the NH3 sensing performance in terms of response, sensitivity and selectivity. The S1 sensing material revealed higher sensitivity of 127.39 at 20 ppm NH3 gas. The sensing mechanism towards NH3 gas is also proposed. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. Biological Low-pH Mn(II) Oxidation in a Manganese Deposit Influenced by Metal-Rich Groundwater

    PubMed Central

    Bohu, Tsing; Akob, Denise M.; Abratis, Michael; Lazar, Cassandre S.

    2016-01-01

    ABSTRACT The mechanisms, key organisms, and geochemical significance of biological low-pH Mn(II) oxidation are largely unexplored. Here, we investigated the structure of indigenous Mn(II)-oxidizing microbial communities in a secondary subsurface Mn oxide deposit influenced by acidic (pH 4.8) metal-rich groundwater in a former uranium mining area. Microbial diversity was highest in the Mn deposit compared to the adjacent soil layers and included the majority of known Mn(II)-oxidizing bacteria (MOB) and two genera of known Mn(II)-oxidizing fungi (MOF). Electron X-ray microanalysis showed that romanechite [(Ba,H2O)2(Mn4+,Mn3+)5O10] was conspicuously enriched in the deposit. Canonical correspondence analysis revealed that certain fungal, bacterial, and archaeal groups were firmly associated with the autochthonous Mn oxides. Eight MOB within the Proteobacteria, Actinobacteria, and Bacteroidetes and one MOF strain belonging to Ascomycota were isolated at pH 5.5 or 7.2 from the acidic Mn deposit. Soil-groundwater microcosms demonstrated 2.5-fold-faster Mn(II) depletion in the Mn deposit than adjacent soil layers. No depletion was observed in the abiotic controls, suggesting that biological contribution is the main driver for Mn(II) oxidation at low pH. The composition and species specificity of the native low-pH Mn(II) oxidizers were highly adapted to in situ conditions, and these organisms may play a central role in the fundamental biogeochemical processes (e.g., metal natural attenuation) occurring in the acidic, oligotrophic, and metalliferous subsoil ecosystems. IMPORTANCE This study provides multiple lines of evidence to show that microbes are the main drivers of Mn(II) oxidation even at acidic pH, offering new insights into Mn biogeochemical cycling. A distinct, highly adapted microbial community inhabits acidic, oligotrophic Mn deposits and mediates biological Mn oxidation. These data highlight the importance of biological processes for Mn biogeochemical cycling

  16. Protective effects of antioxidants and anti-inflammatory agents against manganese-induced oxidative damage and neuronal injury

    SciTech Connect

    Milatovic, Dejan; Gupta, Ramesh C.; Yu, Yingchun; Zaja-Milatovic, Snjezana; Aschner, Michael

    2011-11-15

    Exposure to excessive manganese (Mn) levels leads to neurotoxicity, referred to as manganism, which resembles Parkinson's disease (PD). Manganism is caused by neuronal injury in both cortical and subcortical regions, particularly in the basal ganglia. The basis for the selective neurotoxicity of Mn is not yet fully understood. However, several studies suggest that oxidative damage and inflammatory processes play prominent roles in the degeneration of dopamine-containing neurons. In the present study, we assessed the effects of Mn on reactive oxygen species (ROS) formation, changes in high-energy phosphates and associated neuronal dysfunctions both in vitro and in vivo. Results from our in vitro study showed a significant (p < 0.01) increase in biomarkers of oxidative damage, F{sub 2}-isoprostanes (F{sub 2}-IsoPs), as well as the depletion of ATP in primary rat cortical neurons following exposure to Mn (500 {mu}M) for 2 h. These effects were protected when neurons were pretreated for 30 min with 100 of an antioxidant, the hydrophilic vitamin E analog, trolox (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid), or an anti-inflammatory agent, indomethacin. Results from our in vivo study confirmed a significant increase in F{sub 2}-IsoPs levels in conjunction with the progressive spine degeneration and dendritic damage of the striatal medium spiny neurons (MSNs) of mice exposed to Mn (100 mg/kg, s.c.) 24 h. Additionally, pretreatment with vitamin E (100 mg/kg, i.p.) or ibuprofen (140 {mu}g/ml in the drinking water for two weeks) attenuated the Mn-induced increase in cerebral F{sub 2}-IsoPs? and protected the MSNs from dendritic atrophy and dendritic spine loss. Our findings suggest that the mediation of oxidative stress/mitochondrial dysfunction and the control of alterations in biomarkers of oxidative injury, neuroinflammation and synaptodendritic degeneration may provide an effective, multi-pronged therapeutic strategy for protecting dysfunctional dopaminergic

  17. Elemental abundance analyses with coadded Dominion Astrophysical Observatory spectrograms. II - The mercury-manganese stars 53 Tauri, Mu Leporis and Kappa Cancri

    NASA Technical Reports Server (NTRS)

    Adelman, Saul J.

    1987-01-01

    Elemental abundance analyses based on the coaddition of at least 10 2.4 A/mm Ila-O Dominion Astrophysical Observatory spectrograms have been performed for three mercury-manganese stars, 53 Tauri, Mu Leporis, and Kappa Cancri. These fine analyses show a greater degree of internal consistency than previous studies based on lower signal-to-noise data. Lines as weak as of order 3 mA are employed in these studies, and lines of atomic species not previously identified have been discovered. The status of 53 Tau as an anomalous member of this class is confirmed in that it lacks a Hg II 3984 A line even at the 2 mA level. Further, its surface gravity indicates it is less evolved than Mu Lep and Chi Cnc. Violations of the odd-even effect in the photospheric abundances of all three stars suggest that nonnuclear processes have operated in their atmospheres. Some of the values are substantially changed from their presumably initial solar values.

  18. Evaluation of diethylenetriaminepentaacetic acid-manganese(II) complexes modified by narrow molecular weight distribution of chitosan oligosaccharides as potential magnetic resonance imaging contrast agents.

    PubMed

    Huang, Yan; Zhang, Xiaoyan; Zhang, Qi; Dai, Xueqin; Wu, Jingbo

    2011-05-01

    Novel conjugates of narrow molecular weight distribution of chitosan oligosaccharides (CSn; n=6, 8, 11) with manganese-diethylenetriaminepentaacetic acid (Mn-DTPA) as potential magnetic resonance imaging (MRI) contrast agents were synthesized. The structures were characterized by means of Fourier transform infrared spectra, (13)C nuclear magnetic resonance, size exclusion chromatography and inductively coupled plasma atomic emission spectrometry. The characterization results showed that Mn-DTPA was successfully linked to aminated CSn by an amide function. The magnetic properties were characterized by in vitro and T(1)-weighted FLASH image experiments. Relaxivities studies indicated that Mn-DTPA-CSn (n=8, 11) provided higher relaxivity, either in aqueous or bovine serum albumin solution (0.725 mM), than commercial contrast agent Gd-DTPA. The stability results showed that Mn-DTPA-CSn in aqueous were stable enough to prevent Mn(II) ions from releasing. The preliminary in vitro and T(1)-weighted FLASH image studies suggested that Mn-DTPA-CSn had the advantage of becoming promising MRI contrast agents. Copyright © 2011 Elsevier Inc. All rights reserved.

  19. Crystal structure of bis-(acetato-κO)di-aqua-(2,2'-bi-pyridine-κ(2) N,N')manganese(II).

    PubMed

    Saravanan, Natarajan; Selvam, Parasuraman

    2014-09-01

    In the title monomeric manganese(II) complex, [Mn(CH3COO)2(C10H8N2)(H2O)2], the metal ion is coordinated by a bidentate 2,2'-bi-pyridine (bpy) ligand, two water mol-ecules and two axial acetate anions, resulting in a highly distorted octa-hedral environment. The aqua ligands are stabilized by the formation of strong intra-molecular hydrogen bonds with the uncoordinated acetate O atoms, giving rise to pseudo-bridging arrangement of the terminal acetate groups. In the crystal, the mol-ecules form [010] zigzag chains via O-H⋯O hydrogen bonds involving the aqua ligands and acetate O atoms. Further, the water and bpy ligands are trans to each other, and are arranged in an off-set fashion showing inter-molecular π-π stacking between nearly parallel bi-py rings, the centroid-centroid separations being 3.8147 (12) and 3.9305 (13) Å.

  20. Crystallization and preliminary crystallographic analysis of manganese(II)-dependent 2,3-dihydroxybiphenyl 1,2-dioxygenase from Bacillus sp. JF8.

    PubMed

    Senda, Miki; Hatta, Takashi; Kimbara, Kazuhide; Senda, Toshiya

    2010-03-01

    A thermostable manganese(II)-dependent 2,3-dihydroxybiphenyl-1,2-dioxygenase derived from Bacillus sp. JF8 was crystallized. The initial screening for crystallization was performed by the sitting-drop vapour-diffusion method using a crystallization robot, resulting in the growth of two crystal forms. The first crystal belonged to space group P1, with unit-cell parameters a = 62.7, b = 71.4, c = 93.6 A, alpha = 71.2, beta = 81.0, gamma = 64.0 degrees, and diffracted to 1.3 A resolution. The second crystal belonged to space group I222, with unit-cell parameters a = 74.2, b = 90.8, c = 104.3 A, and diffracted to 1.3 A resolution. Molecular-replacement trials using homoprotocatechuate 2,3-dioxygenase from Arthrobacter globiformis (28% amino-acid sequence identity) as a search model provided a satisfactory solution for both crystal forms.

  1. Elemental abundance analyses with coadded Dominion Astrophysical Observatory spectrograms. II - The mercury-manganese stars 53 Tauri, Mu Leporis and Kappa Cancri

    NASA Technical Reports Server (NTRS)

    Adelman, Saul J.

    1987-01-01

    Elemental abundance analyses based on the coaddition of at least 10 2.4 A/mm Ila-O Dominion Astrophysical Observatory spectrograms have been performed for three mercury-manganese stars, 53 Tauri, Mu Leporis, and Kappa Cancri. These fine analyses show a greater degree of internal consistency than previous studies based on lower signal-to-noise data. Lines as weak as of order 3 mA are employed in these studies, and lines of atomic species not previously identified have been discovered. The status of 53 Tau as an anomalous member of this class is confirmed in that it lacks a Hg II 3984 A line even at the 2 mA level. Further, its surface gravity indicates it is less evolved than Mu Lep and Chi Cnc. Violations of the odd-even effect in the photospheric abundances of all three stars suggest that nonnuclear processes have operated in their atmospheres. Some of the values are substantially changed from their presumably initial solar values.

  2. Spectroscopic characterization of manganese minerals.

    PubMed

    Lakshmi Reddy, S; Padma Suvarna, K; Udayabhaska Reddy, G; Endo, Tamio; Frost, R L

    2014-01-03

    Manganese minerals ardenite, alleghanyite and leucopoenicite originated from Madhya Pradesh, India, Nagano prefecture Japan, Sussex Country and Parker Shaft Franklin, Sussex Country, New Jersey respectively are used in the present work. In these minerals manganese is the major constituent and iron if present is in traces only. An EPR study of on all of the above samples confirms the presence of Mn(II) with g around 2.0. Optical absorption spectrum of the mineral alleghanyite indicates that Mn(II) is present in two different octahedral sites and in leucophoenicite Mn(II) is also in octahedral geometry. Ardenite mineral gives only a few Mn(II) bands. NIR results of the minerals ardenite, leucophoenicite and alleghanyite are due to hydroxyl and silicate anions which confirming the formulae of the minerals.

  3. Environmental manganese compounds accumulate as Mn(II) within the Golgi apparatus of dopamine cells: relationship between speciation, subcellular distribution, and cytotoxicity.

    PubMed

    Carmona, Asuncion; Roudeau, Stéphane; Perrin, Laura; Veronesi, Giulia; Ortega, Richard

    2014-04-01

    Manganese is a neurotoxic element that leads to severe neurological disorders when excessive exposure occurs, mainly in occupational settings, but that can also lead to more subtle neurological deficits, especially to the dopaminergic system, under lower exposure conditions. Mn exists in a variety of chemical species in the environment but the influence of Mn speciation on its neurotoxicity has not been fully evaluated yet. In this study we compared the cytotoxicity towards dopamine producing cells of environmental Mn compounds with a diversity of physico-chemical forms: inorganic compounds having distinct oxidation states and solubility (MnCl2, MnSO4, and Mn2O3) and organic compounds such as MMT, a gasoline additive, and maneb, a Mn-dithiocarbamate fungicide. We observed that maneb exhibited the highest toxicity, followed by MnCl2, MnSO4 and MMT which resulted in a similar intermediate toxicity, the less toxic compound being the insoluble compound Mn2O3. We combined micro-SXRF (Synchrotron X-Ray Fluorescence) for imaging and micro-XANES (X-ray Absorption Near Edge Structure) to determine the Mn oxidation state at the single cell level. Mn2O3 readily entered the cell but remained in its initial state as Mn(III) particles within the cytoplasm. The lack of toxicity of Mn2O3 can be explained by its insolubility. For all the other compounds, Mn(II) was observed and was located mainly in the Golgi apparatus, probably for detoxification purposes via exocytosis. Organic compounds MMT and maneb were degraded releasing Mn and behaved similar to the soluble Mn(II) inorganic compounds. Maneb cytotoxicity was higher probably because of the combined toxicity due to both Mn and dithiocarbamate residues. Overall these results raise the concern about environmental exposure to Mn since either inhalation of Mn combustion products or ingestion of contaminated food and drinking water will end up in neurotoxic soluble and bioavailable Mn species.

  4. Synthesis, and characterization of low- and high-spin manganese(II) complexes of polyfunctional adipoyldihydrazone: Effect of coordination of N-donor ligands on stereo-redox chemistry

    NASA Astrophysics Data System (ADS)

    Basumatary, Debajani; Lal, Ram Ashray; Kumar, Arvind

    2015-07-01

    Manganese(II) complexes [MnII(npahH2)] (1), [MnII(npahH2)(A)2] and [MnII(npahH2)(NN)] (where A = pyridine, (2); 2-picoline, (3); 3-picoline, (4); 4-picoline, (5) and NN = 2,2‧ bipyridine, (6); 1,10-phenanthroline, (7)) have been synthesized from bis(2-hydroxy-1-naphthaldehyde)adipoyldihydrazone (npahH4) in methanol. The composition of metal complexes has been established by elemental analyses. Complexes (1) and (3) have been characterized by mass spectral data also. Structural assessments of the complexes have been based on data obtained from molar conductance, magnetic moment, electronic, electron paramagnetic resonance and infrared spectral studies. Conductivity measurements in DMSO suggest that they are non-electrolyte. Electronic spectral studies suggest a six-coordinate octahedral geometry around the manganese center in complexes (2) to (7) and square-planar geometry in complex (1). IR spectral studies reveal that the dihydrazone coordinates to the metal in keto form with an anti-cis configuration. Magnetic moment, and EPR studies suggest manganese in +2 oxidation state in all complexes with high-spin distorted octahedral stereochemistry in complexes (2-7) while low-spin square-planar stereochemistry is involved with significant metal-metal interactions in the solid state in complex (1). Cyclic voltammetric studies reveal that the metal center cycles among the MnII → MnI → Mn0 in complexes (2) to (7) and among MnII → MnI oxidation states in complex (1).

  5. Manganese nodules

    USGS Publications Warehouse

    Hein, James R.; Harff, Jan; Petersen, Sven; Thiede, Jorn

    2016-01-01

    The existence of manganese (Mn) nodules (Fig. 1) has been known since the late 1800s when they were collected during the Challenger expedition of 1873–1876. However, it was not until after WWII that nodules were further studied in detail for their ability to adsorb metals from seawater. Many of the early studies did not distinguish Mn nodules from Mn crusts. Economic interest in Mn nodules began in the late 1950s and early 1960s when John Mero finished his Ph.D. thesis on this subject, which was published...

  6. Carbon determination in carbon-manganese steels under atmospheric conditions by Laser-Induced Breakdown Spectroscopy.

    PubMed

    Labutin, Timur A; Zaytsev, Sergey M; Popov, Andrey M; Zorov, Nikita B

    2014-09-22

    The most sensitive lines of carbon, used nowadays for its determination in steels by laser-induced-breakdown spectroscopy (LIBS), are at vacuum UV and, thereby, LIBS potential is significantly reduced. We suggested the use of the C I 833.51 nm line for carbon determination in low-alloy steels (c(C)~0.186-1.33 wt.%) in air. Double-pulse LIBS with the collinear scheme was performed for maximal enhancement of a carbon emission signal without substantial complication of experimental setup. Since this line is strongly broadened in laser plasma, it overlapped with the closest iron lines greatly. We implemented a PCR method for the construction of a multivariate calibration model under spectral interferences. The model provided a RMSECV = 0.045 wt.%. The predicted carbon content in the rail templet was in an agreement with the reference value obtained by a combustion analyzer within the relative error of 6%.

  7. Manganese superoxide dismutase is a mitochondrial fidelity protein that protects Polγ against UV-induced inactivation.

    PubMed

    Bakthavatchalu, V; Dey, S; Xu, Y; Noel, T; Jungsuwadee, P; Holley, A K; Dhar, S K; Batinic-Haberle, I; St Clair, D K

    2012-04-26

    Manganese superoxide dismutase is a nuclear encoded primary antioxidant enzyme localized exclusively in the mitochondrial matrix. Genotoxic agents, such as ultraviolet (UV) radiation, generates oxidative stress and cause mitochondrial DNA (mtDNA) damage. The mtDNA polymerase (Polγ), a major constituent of nucleoids, is responsible for the replication and repair of the mitochondrial genome. Recent studies suggest that the mitochondria contain fidelity proteins and MnSOD constitutes an integral part of the nucleoid complex. However, it is not known whether or how MnSOD participates in the mitochondrial repair processes. Using skin tissue from C57BL/6 mice exposed to UVB radiation, we demonstrate that MnSOD has a critical role in preventing mtDNA damage by protecting the function of Polγ. Quantitative-PCR analysis shows an increase in mtDNA damage after UVB exposure. Immunofluorescence and immunoblotting studies demonstrate p53 translocation to the mitochondria and interaction with Polγ after UVB exposure. The mtDNA immunoprecipitation assay with Polγ and p53 antibodies in p53(+/+) and p53(-/-) mice demonstrates an interaction between MnSOD, p53 and Polγ. The results suggest that these proteins form a complex for the repair of UVB-associated mtDNA damage. The data also demonstrate that UVB exposure injures the mtDNA D-loop in a p53-dependent manner. Using MnSOD-deficient mice we demonstrate that UVB-induced mtDNA damage is MnSOD dependent. Exposure to UVB results in nitration and inactivation of Polγ, which is prevented by addition of the MnSOD mimetic Mn(III)TE-2-PyP(5+). These results demonstrate for the first time that MnSOD is a fidelity protein that maintains the activity of Polγ by preventing UVB-induced nitration and inactivation of Polγ. The data also demonstrate that MnSOD has a role along with p53 to prevent mtDNA damage.

  8. A new three-dimensional manganese(II) coordination polymer based on the 1,3,5-tris[(1H-imidazol-1-yl)methyl]benzene ligand.

    PubMed

    Lu, Xin Hua; Zhong, Kai Long

    2016-11-01

    The self-assembly of coordination polymers and the crystal engineering of metal-organic coordination frameworks have attracted great interest, but it is still a challenge to predict and control the compositions and structures of the complexes. Employing multidentate organic ligands and suitable metal ions to construct inorganic-organic hybrid materials through metal-ligand coordination and hydrogen-bonding interactions has become a major strategy. Recently, imidazole-containing multidentate ligands that contain an aromatic core have received much attention. A new three-dimensional Mn(II) coordination polymer based on 1,3,5-tris[(1H-imidazol-1-yl)methyl]benzene, namely poly[(ethane-1,2-diol-κO)(μ-sulfato-κ(2)O:O'){μ3-1,3,5-tris[(1H-imidazol-1-yl)methyl]benzene-κ(3)N:N':N''}manganese(II)], [Mn(SO4)(C18H18N6)(C2H6O2)]n, was synthesized and characterized by elemental analysis, IR spectroscopy and single-crystal X-ray diffraction. Crystal structural analysis shows that there are two kinds of crystallographically independent Mn(II) centres, each lying on a centrosymmetric position and having a similar six-coordinated octahedral structure. One is coordinated by four N atoms from four 1,3,5-tris[(1H-imidazol-1-yl)methyl]benzene (timb) ligands and two O atoms from two different bridging sulfate anions. The second is surrounded by two timb N atoms and four O atoms, two from sulfate anions and two from two ethane-1,2-diol ligands. The tripodal timb ligand bridges neighbouring Mn(II) centres to generate a two-dimensional layered structure running parallel to the ab plane. Adjacent layers are further bridged by sulfate anions, resulting in a three-dimensional structure with 3,4,6-c topology. Thermogravimetric analysis of the title polymer shows that it is stable up to 533 K. The first weight loss between 533 and 573 K corresponds to the release of coordinated ethane-1,2-diol molecules, and further decomposition occurred at 648 K.

  9. Manganese-containing ionic liquids: synthesis, crystal structures and electrodeposition of manganese films and nanoparticles.

    PubMed

    Sniekers, Jeroen; Malaquias, João C; Van Meervelt, Luc; Fransaer, Jan; Binnemans, Koen

    2017-02-21

    Manganese(ii)-containing ionic liquids were synthesized, in which the manganese atoms are coordinated by glymes (diglyme, triglyme, tetraglyme), pyridine-N-oxide, dimethylsulfoxide or N-alkylimidazoles (N-methylimidazole, N-butylimidazole and N-hexylimidazole). As anion, bis(trifluoromethanesulfonyl)imide (bistriflimide, Tf2N(-)), trifluoromethanesulfonate (triflate, OTf(-)) or methanesulfonate (mesylate, OMs(-)) were used. The compounds were characterized by CHN analysis, FTIR, DSC and single-crystal X-ray diffraction measurements. All manganese atoms were six-coordinate. It was found that the glyme-type ligands were replaced by atmospheric water upon leaving the crystals open to the air for several days. The crystal structures of seven compounds were described in detail and the compounds with the lowest melting temperatures were tested as electrolytes for the electrodeposition of manganese (thin) films. An irreversible reduction wave from Mn(ii) to Mn(0) and granular manganese deposits were observed for all compounds, except for liquid manganese salts with N-alkylimidazole ligands and bistriflimide anions, where the electrochemical formation of manganese nanoparticles was observed instead of the deposition of a manganese layer. However, for compounds with the same cation but with a triflate or methanesulfonate anion, manganese metal deposits were obtained, indicating that the nature of the anion has an important effect on the electrochemical properties of liquid metal salts.

  10. Adsorption of Zinc(II) on diatomite and manganese-oxide-modified diatomite: a kinetic and equilibrium study.

    PubMed

    Caliskan, Necla; Kul, Ali Riza; Alkan, Salih; Sogut, Eda Gokirmak; Alacabey, Ihsan

    2011-10-15

    The removal of Zn(II) ions from aqueous solution was studied using natural and MnO(2) modified diatomite samples at different temperatures. The linear Langmuir, Freundlich and Dubinin-Radushkevich (D-R) adsorption equations were applied to describe the equilibrium isotherms. From the D-R model, the mean adsorption energy was calculated as >8 kJ mol(-1), indicating that the adsorption of Zn(II) onto diatomite and Mn-diatomite was physically carried out. In addition, the pseudo-first-order, pseudo-second-order and intraparticle diffusion models were used to determine the kinetic data. The experimental data were well fitted by the pseudo-second-order kinetic model. Thermodynamic parameters such as the enthalpy (ΔH(0)), Gibbs' free energy (ΔG(0)) and entropy (ΔS(0)) were calculated for natural and MnO(2) modified diatomite. These values showed that the adsorption of Zn(II) ions onto diatomite samples was controlled by a physical mechanism and occurred spontaneously. Copyright © 2011 Elsevier B.V. All rights reserved.

  11. Inhalation of Talc Induces Infiltration of Macrophages and Upregulation of Manganese Superoxide Dismutase in Rats.

    PubMed

    Shim, Ilseob; Kim, Hyun-Mi; Yang, Sangyoung; Choi, Min; Seo, Gyun-Baek; Lee, Byung-Woo; Yoon, Byung-Il; Kim, Pilje; Choi, Kyunghee

    2015-01-01

    Talc is a mineral that is widely used in cosmetic products, antiseptics, paints, and rubber manufacturing. Although the toxicological effects of talc have been studied extensively, until now no detailed inhalation study of talc focusing on oxidative stress has been done. This repeated 4 weeks whole-body inhalation toxicity study of talc involved Sprague-Dawley rats. Male and female groups of rats were exposed to inhaled talc at 0, 5, 50, and 100 mg/m(3) for 6 hours daily, 5 days/week for 4 weeks. The objective was to identify the 4-week inhalation toxicity of talc and investigate antioxidant activity after exposure to talc. There were no treatment-related symptoms or mortality in rats treated with talc. Glucose (GLU) was decreased significantly in male rats exposed to 50 and 100 mg/m(3) of talc. Histopathological examination revealed infiltration of macrophages on the alveolar walls and spaces near the terminal and respiratory bronchioles. In male and female rats exposed to 100 mg/m(3) talc, expression of superoxide dismutase 2, a typical biological indicator of oxidative damage, was significantly increased. Thus, inhalation of talc induces macrophage aggregations and oxidative damage in the lung.

  12. Sodium Para-aminosalicylic Acid Protected Primary Cultured Basal Ganglia Neurons of Rat from Manganese-Induced Oxidative Impairment and Changes of Amino Acid Neurotransmitters.

    PubMed

    Li, Shao-Jun; Li, Yong; Chen, Jing-Wen; Yuan, Zong-Xiang; Mo, Yu-Huan; Lu, Guo-Dong; Jiang, Yue-Ming; Ou, Chao-Yan; Wang, Fang; Huang, Xiao-Wei; Luo, Yi-Ni; Ou, Shi-Yan; Huang, Yan-Ni

    2016-04-01

    Manganese (Mn), an essential trace metal for protein synthesis and particularly neurotransmitter metabolism, preferentially accumulates in basal ganglia. However, excessive Mn accumulation may cause neurotoxicity referred to as manganism. Sodium para-aminosalicylic acid (PAS-Na) has been used to treat manganism with unclear molecular mechanisms. Thus, we aim to explore whether PAS-Na can inhibit Mn-induced neuronal injury in basal ganglia in vitro. We exposed basal ganglia neurons with 50 μM manganese chloride (MnCl2) for 24 h and then replaced with 50, 150, and 450 μM PAS-Na treatment for another 24 h. MnCl2 significantly decreased cell viability but increased leakage rate of lactate dehydrogenase and DNA damage (as shown by increasing percentage of DNA tail and Olive tail moment). Mechanically, Mn reduced glutathione peroxidase and catalase activity and interrupted amino acid neurotransmitter balance. However, PAS-Na treatment reversed the aforementioned Mn-induced toxic effects. Taken together, these results showed that PAS-Na could protect basal ganglia neurons from Mn-induced neurotoxicity.

  13. Central Nervous Activity upon Systemic Salicylate Application in Animals with Kanamycin-Induced Hearing Loss--A Manganese-Enhanced MRI (MEMRI) Study.

    PubMed

    Gröschel, Moritz; Götze, Romy; Müller, Susanne; Ernst, Arne; Basta, Dietmar

    2016-01-01

    This study investigated the effect of systemic salicylate on central auditory and non-auditory structures in mice. Since cochlear hair cells are known to be one major target of salicylate, cochlear effects were reduced by using kanamycin to remove or impair hair cells. Neuronal brain activity was measured using the non-invasive manganese-enhanced magnetic resonance imaging technique. For all brain structures investigated, calcium-related neuronal activity was increased following systemic application of a sodium salicylate solution: probably due to neuronal hyperactivity. In addition, it was shown that the central effect of salicylate was not limited to the auditory system. A general alteration of calcium-related activity was indicated by an increase in manganese accumulation in the preoptic area of the anterior hypothalamus, as well as in the amygdala. The present data suggest that salicylate-induced activity changes in the auditory system differ from those shown in studies of noise trauma. Since salicylate action is reversible, central pharmacological effects of salicylate compared to those of (permanent) noise-induced hearing impairment and tinnitus might induce different pathophysiologies. These should therefore, be treated as different causes with the same symptoms.

  14. Effect of MDMA-Induced Axotomy on the Dorsal Raphe Forebrain Tract in Rats: An In Vivo Manganese-Enhanced Magnetic Resonance Imaging Study

    PubMed Central

    Chiu, Chuang-Hsin; Siow, Tiing-Yee; Weng, Shao-Ju; Hsu, Yi-Hua; Huang, Yuahn-Sieh; Chang, Kang-Wei; Cheng, Cheng-Yi; Ma, Kuo-Hsing

    2015-01-01

    3,4-Methylenedioxymethamphetamine (MDMA), also known as “Ecstasy”, is a common recreational drug of abuse. Several previous studies have attributed the central serotonergic neurotoxicity of MDMA to distal axotomy, since only fine serotonergic axons ascending from the raphe nucleus are lost without apparent damage to their cell bodies. However, this axotomy has never been visualized directly in vivo. The present study examined the axonal integrity of the efferent projections from the midbrain raphe nucleus after MDMA exposure using in vivo manganese-enhanced magnetic resonance imaging (MEMRI). Rats were injected subcutaneously six times with MDMA (5 mg/kg) or saline once daily. Eight days after the last injection, manganese ions (Mn2+) were injected stereotactically into the raphe nucleus, and a series of MEMRI images was acquired over a period of 38 h to monitor the evolution of Mn2+-induced signal enhancement across the ventral tegmental area, the medial forebrain bundle (MFB), and the striatum. The MDMA-induced loss of serotonin transporters was clearly evidenced by immunohistological staining consistent with the Mn2+-induced signal enhancement observed across the MFB and striatum. MEMRI successfully revealed the disruption of the serotonergic raphe-striatal projections and the variable effect of MDMA on the kinetics of Mn2+ accumulation in the MFB and striatum. PMID:26378923

  15. Speciation and thermodynamic properties of manganese(II) chloride complexes in hydrothermal fluids: In situ XAS study

    NASA Astrophysics Data System (ADS)

    Tian, Yuan; Etschmann, Barbara; Mei, Yuan; Grundler, Pascal V.; Testemale, Denis; Hazemann, Jean-Louis; Elliott, Peter; Ngothai, Yung; Brugger, Joël

    2014-03-01

    The speciation of Mn(II) in acidic brines under a wide range of conditions (30-550 °C, 600 bar, 0.100-10.344 m chloride and 0.110-2.125 m bromide) was investigated using in situ X-ray Absorption Spectroscopy (XAS). Increasing temperature and/or salinity results in a structural change of the Mn(II) complexes from octahedral to (distorted) tetrahedral. Octahedral species predominate at room temperature within the whole salinity range and persist up to ∼400 °C in low salinity solutions (mCl < 1 m), and tetrahedral species become significant above 300 °C. A combination of EXAFS refinements, Density Functional Theory calculations and ab initio XANES simulations shows that at temperatures ⩾400 °C, the highest order chlorocomplex predominating in high salinity solutions (mCl > 3 m, Cl:Mn ratio > 53) is MnCl3(H2O)-, and that a lower order chlorocomplex, MnCl2(H2O)2(aq), is the predominant species in low salinity solutions (mCl < 0.5 m, Cl:Mn ratio < 10). A similar result was also found in Mn bromide solutions: MnBr3(H2O)- and MnBr2(H2O)2(aq) are the dominant species at 500 °C in high salinity solutions (e.g., 2.125 m, Br:Mn ratio = 33.73) and in low salinity solutions (e.g., 0.110 m, Br:Mn ratio = 2.04), respectively. XANES spectra of Mn(II) chloride solutions were used to retrieve formation constants of MnCl2(H2O)2(aq) and MnCl3(H2O)- at 600 bar. The speciation and thermodynamic model of this study are consistent with previous solubility and UV-Vis spectroscopic studies.

  16. Degradation of 17beta-estradiol in aqueous solution by ozonation in the presence of manganese(II) and oxalic acid.

    PubMed

    Jiang, Liying; Zhang, Lu; Chen, Jianmeng; Ji, Hong

    2013-01-01

    Natural estrogens, such as 17beta-estradiol (E2), are the main substances responsible for estrogenic activity found in domestic sewage. In the work described herein, the degradation of E2 has been investigated by single ozonation and catalytic ozonation in the presence of manganese ion (Mn2+) and oxalic acid. The presence of Mn2+ and oxalic acid in the ozonation processes significantly improved the E2 degradation and, hence, the reduction of estrogenic activity in aqueous solution. The addition of Mn2+ and oxalic acid produced many more hydroxyl radicals in the catalytic ozonation system than in the single ozonation system. Oxidation products formed during ozonation of E2 have been identified by means of gas chromatography-mass spectrometry (GC-MS), on the basis of which a possible reaction pathway for E2 degradation by ozonation is proposed. E2 was first oxidized to hydroxyl-semiquinone isomers, and these were subsequently degraded to low molecular weight compounds such as oxalic acid and malonic acid. The latter were easily oxidized by ozone to form carbon dioxide (CO2). The results demonstrate that the ozonation-Mn(2+)-oxalic acid system may serve as a powerful tool for removing E2, and the addition of Mn2+ and oxalic acid is favourable for the complete removal of estrogenic activity induced by steroid estrogens in aqueous solution.

  17. Employment of methyl 2-pyridyl ketone oxime in manganese non-carboxylate chemistry: Mn(II)(2)Mn(IV) and Mn(II)(2)Mn(III)(6) complexes.

    PubMed

    Stoumpos, Constantinos C; Stamatatos, Theocharis C; Sartzi, Harikleia; Roubeau, Olivier; Tasiopoulos, Anastasios J; Nastopoulos, Vassilios; Teat, Simon J; Christou, George; Perlepes, Spyros P

    2009-02-14

    The employment of the anion of methyl 2-pyridyl ketone oxime (mpko(-)) as a tridentate chelating/bridging ligand in manganese chemistry is described. The inorganic anion (Br(-), ClO(4)(-)) used in the reaction affects the identity of the product. The reaction of MnBr(2) and one equivalent of mpkoH in the presence of a base affords [Mn(3)(OMe)(2)(mpko)(4)Br(2)] (3), which is mixed-valence (2Mn(II), Mn(IV)). The central Mn(IV) atom in each of the two, crystallographically independent, centrosymmetric molecules is coordinated by four oximate oxygen atoms belonging to the eta(1):eta(1):eta(1):mu mpko(-) ligands, and two eta(1):mu MeO(-) groups, while six coordination at each terminal Mn(II) atom is completed by four nitrogen atoms belonging to the 'chelating' part of two mpko(-) ligands, and one Br(-) ion. The Mn(II) atoms have trigonal prismatic coordination geometry. The reaction of Mn(ClO(4))(2).6H(2)O, mpkoH and OH(-) (1:2:1) in MeOH gives [Mn(8)O(4)(OMe)(mpko)(9)(mpkoH)](ClO(4))(4) (4), which is also mixed-valence (2Mn(II), 6Mn(III)) and possesses the novel [Mn(8)(mu(3)-O)(4)(mu-OMe)(mu-OR'')(2)](11+) core. The latter possesses a U-shaped sequence of four fused {Mn(II)Mn(III)(2)(mu(3)-O)}(6+) triangular units, with a Mn(III)-Mn(III) edge being shared between the central triangles. Variable-temperature, solid-state dc and ac magnetic susceptibility studies were carried out on complexes 3 and 4 . The dc susceptibility data for 3 in the 5.0-300 K range have been fit to a model with two J values, revealing weak ferromagnetic Mn(II)Mn(IV) (J = +3.4 cm(-1)) and Mn(II)Mn(II) (J' = +0.3 cm(-1)) exchange interactions. Fitting of the magnetization vs. H/T data by matrix diagonalization and including only axial anisotropy (ZFS, D) gave ground state spin (S) and D values of S = 13/2, D = +0.17 cm(-1) for and S = 3, D = -0.09 cm(-1) for 4 . The combined work demonstrates the usefulness of mpko(-) in the preparation of interesting Mn clusters, without requiring the co

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

    NASA Technical Reports Server (NTRS)

    Aguilar, C.; Nealson, K. H.

    1998-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Aguilar, C.; Nealson, K. H.

    1998-01-01

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

  20. Angiotensin II type 1 receptor-mediated augmentation of renal interstitial fluid angiotensin II in angiotensin II-induced hypertension.

    PubMed

    Nishiyama, Akira; Seth, Dale M; Navar, L Gabriel

    2003-10-01

    Angiotensin II (Ang II)-dependent hypertension is associated with augmented intrarenal concentrations of Ang II; however, the distribution of the increased intrarenal Ang II has not been fully established. To determine the changes in renal interstitial fluid Ang II concentrations in Ang II-induced hypertension and the consequences of treatment with an angiotensin II type 1 (AT1) receptor blocker. Rats were selected to receive vehicle (5% acetic acid subcutaneously; n = 6), Ang II (80 ng/min subcutaneously, via osmotic minipump; n = 7) or Ang II plus an AT1 receptor antagonist, candesartan cilexetil (10 mg/kg per day, in drinking water; n = 6) for 13-14 days, at which time, experiments were performed on anesthetized rats. Microdialysis probes were implanted in the renal cortex and were perfused at 2 microl/min. The effluent dialysate concentrations of Ang I and Ang II were measured by radioimmunoassay and reported values were corrected for the equilibrium rates at this perfusion rate. Ang II-infused rats developed greater mean arterial pressures (155 +/- 7 mmHg) than vehicle-infused rats (108 +/- 3 mmHg). Ang II-infused rats showed greater plasma (181 +/- 30 fmol/ml) and kidney (330 +/- 38 fmol/g) Ang II concentrations than vehicle-infused rats (98 +/- 14 fmol/ml and 157 +/- 22 fmol/g, respectively). Renal interstitial fluid Ang II concentrations were much greater than plasma concentrations, averaging 5.74 +/- 0.26 pmol/ml in Ang II-infused rats - significantly greater than those in vehicle-infused rats (2.86 +/- 0.23 pmol/ml). Candesartan treatment prevented the hypertension (87 +/- 3 mmHg) and led to increased plasma Ang II concentrations (441 +/- 27 fmol/ml), but prevented increases in kidney (120 +/- 15 fmol/g) and renal interstitial fluid (2.15 +/- 0.12 pmol/ml) Ang II concentrations. These data indicate that Ang II-infused rats develop increased renal interstitial fluid concentrations of Ang II, which may contribute to the increased vascular resistance and

  1. NMR investigation of field-induced magnetic order in barium manganese oxide

    NASA Astrophysics Data System (ADS)

    Suh, Steve

    As early as 1956, Matsubara and Matsuda found an exact correspondence between a lattice gas model and a quantum antiferromagnet model[1]. They paved the way for the language of integer spin boson particles to be used interchangeably with quantum magnetic insulator systems in a general manner. For example, an analogy of density of bosons is found in magnetization, and analogy of chemical potential is found in external field. Just as there exist corresponding parameters between these two seemingly unrelated systems, quantum magnets can also exhibit consequences of Boson particle systems. In particular, spin-ordering transition in quantum magnets can be interpreted as Bose-Einstein condensate (BEC) transition in Boson particle framework. Direct observation of BEC in Boson particles has been realized in 4He's superfluid transition and in dilute atomic gas clouds cooled to very low temperatures[2]. In this thesis, we try to realize and analyze BEC transition through field-induced spin-ordering transition in the S = 1 antiferromagnetic dimer system, Ba3Mn2O8. We perform NMR measurements with 135,137Ba nucleus as a local probe. Although S = 1 spin properties of Ba 3Mn2O8 come from electronic spins on Mn atoms, hyperfine coupling between Mn electronic spins and Ba nuclear spins allow us to infer Mn electrons' spin information. Since there are 2 inequivalent Ba sites, Ba(1) and Ba(2), in Ba3Mn2O8, we essentially have two probes that provide a detailed picture of structure and nature of magnetism in this material. There are many antiferromagnetic BEC candidates, but there is a significant advantage of studying Ba3Mn 2O8. Unlike the other popular antiferromagnetic BEC candidates such as TlCuCl3[3] or BaCuSi2O6[4], we find no evidence of lattice deformation in Ba3Mn2O8 . This allows us an unprecedented clean look at magnetic properties. Aside from the aforementioned simple technical advantage, there are new physics that we can learn from Ba3Mn2O 8. The geometric frustration of

  2. Preparation and Properties of an Mn(IV-)Hydroxide Complex: Proton and Electron Transfer at a Mononuclear Manganese Site and its Relationship to the Oxygen Evolving Complex within Photosystem II.

    PubMed

    Taguchi, Taketo; Stone, Kari L; Gupta, Rupal; Kaiser-Lassalle, Benedikt; Yano, Junko; Hendrich, Michael P; Borovik, A S

    2014-08-01

    Photosynthetic water oxidation is catalyzed by a Mn4O5Ca cluster with an unprecedented arrangement of metal ions in which a single manganese center is bonded to a distorted Mn3O4Ca cubane-like structure. Several mechanistic proposals describe the unique manganese center as a site for water binding and subsequent formation of a high valent Mn-oxo center that reacts with a M-OH unit (M = Mn or Ca(II)) to form the O-O bond. The conversion of low valent Mn-OHn (n = 1,2) to a Mn-oxo species requires that a single manganese site be able to accommodate several oxidation states as the water ligand is deprotonated. To study these processes, the preparation and characterization of a new monomeric Mn(IV)-OH complex is described. The Mn(IV)-OH complex completes a series of well characterized Mn-OH and Mn-oxo complexes containing the same primary and secondary coordination spheres; this work thus demonstrates that a single ligand can support mononuclear Mn complexes spanning four different oxidation states (II through V) with oxo and hydroxo ligands that are derived from water. Moreover, we have completed a thermodynamic analysis based on this series of manganese complexes to predict the formation of high valent Mn-oxo species; we demonstrated that the conversion of a Mn(IV)-OH species to a Mn(V)-oxo complex would likely occur via a stepwise proton transfer-electron transfer mechanism. The large dissociation energy for the Mn(IV)O-H bond (~95 kcal/mol) diminished the likelihood that other pathways are operative within a biological context. Furthermore, these studies showed that reactions between Mn-OH and Mn-oxo complexes lead to non-productive, one-electron processes suggesting that initial O-O bond formation with the OEC does not involve an Mn-OH unit.

  3. Chloride ligation in inorganic manganese model compounds relevant to Photosystem II studied using X-ray absorption spectroscopy

    PubMed Central

    Pizarro, Shelly A.; Visser, Hendrik; Cinco, Roehl M.; Robblee, John H.; Pal, Samudranil; Mukhopadhyay, Sumitra; Mok, Henry J.; Sauer, Kenneth; Wieghardt, Karl; Armstrong, William H.

    2014-01-01

    Chloride ions are essential for proper function of the photosynthetic oxygen-evolving complex (OEC) of Photosystem II (PS II). Although proposed to be directly ligated to the Mn cluster of the OEC, the specific structural and mechanistic roles of chloride remain unresolved. This study utilizes X-ray absorption spectroscopy (XAS) to characterize the Mn–Cl interaction in inorganic compounds that contain structural motifs similar to those proposed for the OEC. Three sets of model compounds are examined; they possess core structures MnIV3O4X (X = Cl, F, or OH) that contain a di-μ-oxo and two mono-μ-oxo bridges or MnIV2O2X (X = Cl, F, OH, OAc) that contain a di-μ-oxo bridge. Each set of compounds is examined for changes in the XAS spectra that are attributable to the replacement of a terminal OH or F ligand, or bridging OAc ligand, by a terminal Cl ligand. The X-ray absorption near edge structure (XANES) shows changes in the spectra on replacement of OH, OAc, or F by Cl ligands that are indicative of the overall charge of the metal atom and are consistent with the electronegativity of the ligand atom. Fourier transforms (FTs) of the extended X-ray absorption fine structure (EXAFS) spectra reveal a feature that is present only in compounds where chloride is directly ligated to Mn. These FT features were simulated using various calculated Mn–X interactions (X = O, N, Cl, F), and the best fits were found when a Mn–Cl interaction at a 2.2–2.3 Å bond distance was included. There are very few high-valent Mn halide complexes that have been synthesized, and it is important to make such a comparative study of the XANES and EXAFS spectra because they have the potential for providing information about the possible presence or absence of halide ligation to the Mn cluster in PS II. PMID:14758524

  4. Crystal structure of hexa­kis­(dimethyl sulfoxide-κO)manganese(II) tetra­iodide

    PubMed Central

    Haque, Md Azimul; Davaasuren, Bambar; Rothenberger, Alexander; Wu, Tom

    2016-01-01

    The title salt, [Mn(C2H6OS)6]I4, is made up from discrete [Mn(DMSO)6]2+ (DMSO is dimethyl sulfoxide) units connected through non-classical hydrogen bonds to linear I4 2− tetra­iodide anions. The MnII ion in the cation, situated on a position with site symmetry -3., is octa­hedrally coordinated by O atoms of the DMSO mol­ecule with an Mn—O distance of 2.1808 (12) Å. The I4 2− anion contains a neutral I2 mol­ecule weakly coordinated by two iodide ions, forming a linear centrosymmetric tetra­iodide anion. The title compound is isotypic with the Co, Ni, Cu, and Zn analogues. PMID:27980832

  5. A new quantum chemical approach to the magnetic properties of oligonuclear transition-metal complexes: application to a model for the tetranuclear manganese cluster of photosystem II.

    PubMed

    Pantazis, Dimitrios A; Orio, Maylis; Petrenko, Taras; Zein, Samir; Bill, Eckhard; Lubitz, Wolfgang; Messinger, Johannes; Neese, Frank

    2009-01-01

    The reliable correlation of structural features and magnetic or spectroscopic properties of oligonuclear transition-metal complexes is a critical requirement both for research into innovative magnetic materials and for elucidating the structure and function of many metalloenzymes. We have developed a novel method that for the first time enables the extraction of hyperfine coupling constants (HFCs) from broken-symmetry density functional theory (BS-DFT) calculations on clusters. Using the geometry-optimized tetranuclear manganese complex [Mn(4)O(6)(bpy)(6)](4+/3+) as a model, we first examine in detail the calculation of exchange coupling constants J through the BS-DFT approach. Complications arising from the indeterminacy of experimentally fitted J constants are identified and analyzed. It is found that only the energy levels derived from Hamiltonian diagonalization are a physically meaningful basis for comparing theory and experiment. Subsequently, the proposed theoretical scheme is applied to the calculation of (55)Mn HFCs of the Mn(III,IV,IV,IV) state of the complex, which is similar to the S(2) state of the oxygen-evolving complex (OEC) in photosystem II of oxygenic photosynthesis. The new approach performs reliably and accurately, and yields calculated HFCs that can be directly compared with experimental data. Finally, we carefully examine the dependence of HFC on the J value and draw attention to the sensitivity of the calculated values to the exchange coupling parameters. The proposed strategy extends naturally to hetero-oligonuclear clusters of arbitrary shape and nuclearity, and hence is of general validity and usefulness in the study of magnetic metal clusters. The successful application of the new approach presented here is a first step in the effort to establish correlations between the available spectroscopic information and the structural features of complex metalloenzymes like OEC.

  6. Quantitative iTRAQ-based secretome analysis reveals species-specific and temporal shifts in carbon utilization strategies among manganese(II)-oxidizing Ascomycete fungi

    DOE PAGES

    Zeiner, Carolyn A.; Purvine, Samuel O.; Zink, Erika M.; ...

    2017-07-01

    Fungi generate a wide range of extracellular hydrolytic and oxidative enzymes and reactive metabolites, collectively known as the secretome, that synergistically drive plant litter decomposition in the environment. While secretome studies of model organisms have greatly expanded our knowledge of these enzymes, few have extended secretome characterization to environmental isolates, particularly filamentous Ascomycetes, or directly compared temporal patterns of enzyme utilization among diverse species. Thus, the mechanisms of carbon (C) degradation by many ubiquitous soil fungi remain poorly understood. Here in this study we use a combination of iTRAQ proteomics and extracellular enzyme activity assays to compare the protein compositionmore » of the secretomes of four manganese(II)-oxidizing Ascomycete fungi over a three-week time course. We demonstrate that the fungi exhibit striking differences in the regulation of extracellular lignocellulose-degrading enzymes among species and over time, revealing species-specific and temporal shifts in C utilization strategies as they degrade the same substrate. Specifically, our findings suggest that Alternaria alternata SRC1lrK2f and Paraconiothyrium sporulosum AP3s5-JAC2a employ sequential enzyme secretion patterns concomitant with decreasing resource availability. Stagonospora sp. SRC1lsM3a preferentially degrades proteinaceous substrate before switching to carbohydrates, and Pyrenochaeta sp. DS3sAY3a utilizes primarily peptidases to aggressively attack carbon sources in a concentrated burst. In conclusion, this work highlights the diversity of operative metabolic strategies among understudied yet ubiquitous cellulose-degrading Ascomycetes, enhancing our understanding of their contribution to C turnover in the environment.« less

  7. A density functional theory study of the magnetic exchange coupling in dinuclear manganese(II) inverse crown structures.

    PubMed

    Vélez, Ederley; Alberola, Antonio; Polo, Víctor

    2009-12-17

    The magnetic exchange coupling constants between two Mn(II) centers for a set of five inverse crown structures have been investigated by means of a methodology based on broken-symmetry unrestricted density functional theory. These novel and highly unstable compounds present superexchange interactions between two Mn centers, each one with S = 5/2 through anionic "guests" such as oxygen, benzene, or hydrides or through the cationic ring formed by amide ligands and alkali metals (Na, Li). Magnetic exchange couplings calculated at B3LYP/6-31G(d,p) level yield strong antiferromagnetic couplings for compounds linked via an oxygen atom or hydride and very small antiferromagnetic couplings for those linked via a benzene molecule, deprotonated in either 1,4- or 1,3- positions. Analysis of the magnetic orbitals and spin polarization maps provide an understanding of the exchange mechanism between the Mn centers. The dependence of J with respect to 10 different density functional theory potentials employed and the basis set has been analyzed.

  8. Multifrequency electron spin-echo envelope modulation studies of nitrogen ligation to the manganese cluster of photosystem II

    PubMed Central

    Yeagle, Gregory J; Gilchrist, M. Lane; Walker, Lee M; Debus, Richard J; Britt, R. David

    2007-01-01

    The CalEPR Center at UC-Davis (http://brittepr.ucdavis.edu) is equipped with five research grade electron paramagnetic resonance (EPR) instruments operating at various excitation frequencies between 8 and 130 GHz. Of particular note for this RSC meeting are two pulsed EPR spectrometers working at the intermediate microwave frequencies of 31 and 35 GHz. Previous lower frequency electron spin-echo envelope modulation (ESEEM) studies indicated that histidine nitrogen is electronically coupled to the Mn cluster in the S2 state of photosystem II (PSII). However, the amplitude and resolution of the spectra were relatively poor at these low frequencies, precluding any in-depth analysis of the electronic structure properties of this closely associated nitrogen nucleus. With the intermediate frequency instruments, we are much closer to the ‘exact cancellation’ limit, which optimizes ESEEM spectra for hyperfine-coupled nuclei such as 14N and 15N. Herein, we report the results from ESEEM studies of both 14N- and 15N-labelled PSII at these two frequencies. Spectral simulations were constrained by both isotope datasets at both frequencies, with a focus on high-resolution spectral examination of the histidine ligation to the Mn cluster in the S2 state. PMID:17954435

  9. catena-Poly[[[diaqua­bis[4-(diethyl­amino)benzoato-κO]manganese(II)]-μ-aqua] dihydrate

    PubMed Central

    Hökelek, Tuncer; Dal, Hakan; Tercan, Barış; Aybirdi, Özgür; Necefoğlu, Hacali

    2009-01-01

    In the crystal structure of the title complex, {[Mn(C11H14NO2)2(H2O)3]·2H2O}n, the two independent MnII atoms are located on a centre of symmetry and coordinated by two 4-(diethyl­amino)benzoate (DEAB) anions and two water mol­ecules in the basal plane while another water mol­ecule bridges the Mn atoms in the apical directions, forming polymeric chains. The dihedral angles between the carboxyl­ate groups and the adjacent benzene rings are 11.33 (13) and 10.90 (9)° and the benzene rings are oriented at a dihedral angle of 67.88 (6)°. The uncoordinated water mol­ecules link the carboxyl­ate groups and coordinated water mol­ecules via O—H⋯O hydrogen bonding. Weak C—H⋯π inter­actions are also found in the crystal structure. PMID:21582685

  10. Structural consequences of ammonia binding to the manganese center of the photosynthetic oxygen-evolving complex: an X-ray absorption spectroscopy study of isotropic and oriented photosystem II particles.

    PubMed

    Dau, H; Andrews, J C; Roelofs, T A; Latimer, M J; Liang, W; Yachandra, V K; Sauer, K; Klein, M P

    1995-04-18

    The structure and orientation of the manganese complex in NH3-treated photosystem II (PS II) membrane particles of spinach are being studied by X-ray absorption spectroscopy. On the basis of earlier work by our group, a structure for the tetranuclear manganese complex of PS II, which consists of two di-mu-oxo-bridged binuclear Mn units linked by a mono-mu-oxo group, has been proposed [Yachandra, V. K., et al. (1993) Science 260, 675-679]. The extended X-ray absorption fine structure (EXAFS) of the complex modified by NH3 binding in the S2-state is suggestive of an increase in the Mn-Mn distance of one of these units from 2.72 +/- 0.02 to 2.87 +/- 0.02 A, whereas the Mn-Mn distance of the second unit seems to be unaffected by NH3 treatment. The elongation of one binuclear center could result from the replacement of one bridging mu-oxo by an amido group. The lengthening of one Mn-Mn distance means that, by NH3 treatment, the distance degeneracy of the 2.7 A Mn-Mn EXAFS interaction is removed. Consequently, the orientation of individual binuclear units with respect to the membrane normal becomes resolvable by EXAFS spectroscopy of partially oriented PS II membrane particles. The angle between the normal of the PS II-containing membrane and the Mn-Mn vector is determined to be 67 degrees +/- 3 degrees for the 2.87 A distance and 55 degrees +/- 4 degrees for the 2.72 A distance. Only small effects on position, shape, and orientation dependence of Mn K-edge spectra result from NH3 treatment, indicating that the Mn oxidation state, the symmetry of the Mn ligand environment, and the orientation of the complex remain essentially unaffected in the annealed NH3 S2-state. Therefore, it seems likely that the angles determined for the ammonia-modified manganese complex are similar to the respective angles of the untreated complex. The structure of the manganese complex and its orientation in the membrane are discussed.

  11. Synthesis, crystal structures and properties of three glutarato and adipato bridged manganese(II) coordination polymers under ambient conditions

    NASA Astrophysics Data System (ADS)

    Zheng, Yue-Qing; Zhu, Hong-Lin; Guo, Xia-Xia; Liu, Ji-Yong

    2013-04-01

    Three Mn(II) polymers Mn(H2O)4(C5H6O4) 1, [Mn(H2O)2(C5H6O4)]·H2O 2 and Mn(H2O)(C6H8O4) 3 were synthesized (H2(C5H6O4) = glutaric acid, H2(C6H8O4) = adipic acid) under mild ambient conditions. The [Mn(H2O)2]2+ units in 2 are interlinked by the glutarate anions with a η4μ3 bridging mode to form 2D (4·82) topological networks, which are stacked via interlayer hydrogen bonds into a 3D (43·65·82)(47·63) topological net. Compound 3 crystallizes in the acentric space group P21 and exhibits significant ferroelectricity (remnant polarization Pr = 0.371 nC cm-2, coercive field Ec = 0.028 kV cm-1, saturation of the spontaneous polarization Ps = 0.972 nC cm-2). The adjacent MnO6 octahedrons in 3 are one atom-shared to generate the Mn2O11 bi-octahedron, leading into 1D metal oxide chains. The resulting chains are interconnected by the η5μ5 adipate anions to form new 2D (48·62) networks, which are held together via strong interlayer hydrogen bonds into 3D α-Po topological supra-molecular architecture. The temperature-dependent magnetic susceptibility data of 1-3 shows overall anti-ferromagnetic interactions between the metal ions bridged by the carboxylate groups.

  12. A dinuclear manganese(II) complex with the [Mn(2)(mu-O(2)CCH(3))(3)](+) core: synthesis, structure, characterization, electroinduced transformation, and catalase-like activity.

    PubMed

    Romero, Isabel; Dubois, Lionel; Collomb, Marie-Noëlle; Deronzier, Alain; Latour, Jean-Marc; Pécaut, Jacques

    2002-04-08

    Reactions of Mn(II)(PF(6))(2) and Mn(II)(O(2)CCH(3))(2).4H(2)O with the tridentate facially capping ligand N,N-bis(2-pyridylmethyl)ethylamine (bpea) in ethanol solutions afforded the mononuclear [Mn(II)(bpea)](PF(6))(2) (1) and the new binuclear [Mn(2)(II,II)(mu-O(2)CCH(3))(3)(bpea)(2)](PF(6)) (2) manganese(II) compounds, respectively. Both 1 and 2 were characterized by X-ray crystallographic studies. Complex 1 crystallizes in the monoclinic system, space group P2(1)/n, with a = 11.9288(7) A, b = 22.5424(13) A, c =13.0773(7) A, alpha = 90 degrees, beta = 100.5780(10 degrees ), gamma = 90 degrees, and Z = 4. Crystals of complex 2 are orthorhombic, space group C222(1), with a = 12.5686(16) A, b = 14.4059(16) A, c = 22.515(3) A, alpha = 90 degrees, beta = 90 degrees, gamma = 90 degrees, and Z = 4. The three acetates bridge the two Mn(II) centers in a mu(1,3) syn-syn mode, with a Mn-Mn separation of 3.915 A. A detailed study of the electrochemical behavior of 1 and 2 in CH(3)CN medium has been made. Successive controlled potential oxidations at 0.6 and 0.9 V vs Ag/Ag(+) for a 10 mM solution of 2 allowed the selective and nearly quantitative formation of [Mn(III)(2)(mu-O)(mu-O(2)CCH(3))(2)(bpea)(2)](2+) (3) and [Mn(IV)(2)(mu-O)(2)(mu-O(2)CCH(3))(bpea)(2)](3+) (4), respectively. These results have shown that each substitution of an acetate group by an oxo group is induced by a two-electron oxidation of the corresponding dimanganese complexes. Similar transformations have been obtained if 2 is formed in situ either by direct mixing of Mn(2+) cations, bpea ligand, and CH(3)COO(-) anions with a 1:1:3 stoichiometry or by mixing of 1 and CH(3)COO(-) with a 1:1.5 stoichiometry. Associated electrochemical back-transformations were investigated. 2, 3, and the dimanganese [Mn(III)Mn(IV)(mu-O)(2)(mu-O(2)CCH(3))(bpea)(2)](2+) analogue (5) were also studied for their ability to disproportionate hydrogen peroxide. 2 is far more active compared to 3 and 5. The EPR monitoring of the

  13. ADP-Ribose Pyrophosphatase Reaction in Crystalline State Conducted by Consecutive Binding of Two Manganese(II) Ions as Cofactors.

    PubMed

    Furuike, Yoshihiko; Akita, Yuka; Miyahara, Ikuko; Kamiya, Nobuo

    2016-03-29

    Adenosine diphosphate ribose pyrophosphatase (ADPRase), a member of the Nudix family proteins, catalyzes the metal-induced and concerted general acid-base hydrolysis of ADP ribose (ADPR) into AMP and ribose-5'-phosphate (R5P). The ADPR-hydrolysis reaction of ADPRase from Thermus thermophilus HB8 (TtADPRase) requires divalent metal cations such as Mn(2+), Zn(2+), or Mg(2+) as cofactors. Here, we report the reaction pathway observed in the catalytic center of TtADPRase, based on cryo-trapping X-ray crystallography at atomic resolutions around 1.0 Å using Mn(2+) as the reaction trigger, which was soaked into TtADPRase-ADPR binary complex crystals. Integrating 11 structures along the reaction timeline, five reaction states of TtADPRase were assigned, which were ADPRase alone (E), the ADPRase-ADPR binary complex (ES), two ADPRase-ADPR-Mn(2+) reaction intermediates (ESM, ESMM), and the postreaction state (E'). Two Mn(2+) ions were inserted consecutively into the catalytic center of the ES-state and ligated by Glu86 and Glu82, which are highly conserved among the Nudix family, in the ESM- and ESMM-states. The ADPR-hydrolysis reaction was characterized by electrostatic, proximity, and orientation effects, and by preferential binding for the transition state. A new reaction mechanism is proposed, which differs from previous ones suggested from structure analyses with nonhydrolyzable substrate analogues or point-mutated ADPRases.

  14. Central interactions of aldosterone and angiotensin II in aldosterone- and angiotensin II-induced hypertension.

    PubMed

    Xue, Baojian; Beltz, Terry G; Yu, Yang; Guo, Fang; Gomez-Sanchez, Celso E; Hay, Meredith; Johnson, Alan Kim

    2011-02-01

    Many studies have implicated both angiotensin II (ANG II) and aldosterone (Aldo) in the pathogenesis of hypertension, the progression of renal injury, and cardiac remodeling after myocardial infarction. In several cases, ANG II and Aldo have been shown to have synergistic interactions in the periphery. In the present studies, we tested the hypothesis that ANG II and Aldo interact centrally in Aldo- and ANG II-induced hypertension in male rats. In rats with blood pressure (BP) and heart rate (HR) measured by DSI telemetry, intracerebroventricular (icv) infusions of the mineralocorticoid receptor (MR) antagonists spironolactone and RU28318 or the angiotensin type 1 receptor (AT1R) antagonist irbesartan significantly inhibited Aldo-induced hypertension. In ANG II-induced hypertension, icv infusion of RU28318 significantly reduced the increase in BP. Moreover, icv infusions of the reactive oxygen species (ROS) scavenger tempol or the NADPH oxidase inhibitor apocynin attenuated Aldo-induced hypertension. To confirm these effects of pharmacological antagonists, icv injections of either recombinant adeno-associated virus carrying siRNA silencers of AT1aR (AT1aR-siRNA) or MR (MR-siRNA) significantly attenuated the development of Aldo-induced hypertension. The immunohistochemical and Western blot analyses of AT1aR-siRNA- or MR-siRNA-injected rats showed a marked reduction in the expression of AT1R or MR in the paraventricular nucleus compared with scrambled siRNA rats. When animals from all studies underwent ganglionic blockade with hexamethonium, there was a smaller reduction in the fall of BP in animals receiving icv AT1R or MR antagonists. These results suggest that ANG II and Aldo interact in the brain in a mutually cooperative manner such that the functional integrity of both brain AT1R and MR are necessary for hypertension to be induced by either systemic ANG II or Aldo. The pressor effects produced by systemic ANG II or Aldo involve increased central ROS and

  15. Synthesis, X-ray structure, spectroscopic characterization and nonlinear optical properties of triaqua(1,10-phenanthroline-2,9-dicarboxylato)manganese(II) dihydrate: A combined experimental and theoretical study

    NASA Astrophysics Data System (ADS)

    Tamer, Ömer; Avcı, Davut; Atalay, Yusuf; Çoşut, Bünyemin; Zorlu, Yunus; Erkovan, Mustafa; Yerli, Yusuf

    2015-11-01

    The triaqua(1,10-phenanthroline-2,9-dicarboxylato)manganese(II) dihydrate complex was prepared and its crystal structure was determined by using single crystal X-ray diffraction. Its structure was also characterized by the applying of FT-IR, Raman and UV-vis spectroscopies. The manganese(II) ion was located to center of distorted pentagonal-bipyramidal geometry. Electron paramagnetic resonance (EPR) measurement was carried out on the Mn(II) complex. In order to support experimental results, density functional theory calculations were performed at HSEH1PBE level and LanL2DZ basis set. Obtained results indicated that theoretical results can replace the experimental ones. The relatively active ν(CO) ν(CC) and ν(CN) stretching vibration peaks appeared in IR and Raman spectra of complex 1 which are indicators of charge transfer within complex 1 suggest that complex 1 is a good candidate for nonlinear optical materials. The HOMO and LUMO energies determined that complex 1 is stable and the charge transfer occurs within complex 1.

  16. Aqua­(dicyanamido-κN 1)(nitrato-κ2 O,O′)(2,3,5,6-tetra-2-pyridylpyrazine-κ3 N 2,N 1,N 6)manganese(II)

    PubMed Central

    Callejo, Lorena; De la Pinta, Noelia; Vitoria, Pablo; Cortés, Roberto

    2009-01-01

    In the title compound, [Mn(C2N3)(NO3)(C24H16N6)(H2O)], the central manganese(II) ion is hepta­coordinated to a tridentate 2,3,5,6-tetra-2-pyridylpyrazine ligand (tppz), a bidentate nitrate ligand, a terminal monodentate dicyanamide ligand (dca) and a water mol­ecule. The structure contains isolated neutral complexes, which are linked by O(water)—H⋯N hydrogen bonds generating chains along [010]. PMID:21581535

  17. Angiotensin II Induced Cardiac Dysfunction on a Chip

    PubMed Central

    Horton, Renita E.; Yadid, Moran; McCain, Megan L.; Sheehy, Sean P.; Pasqualini, Francesco S.; Park, Sung-Jin; Cho, Alexander; Campbell, Patrick; Parker, Kevin Kit

    2016-01-01

    In vitro disease models offer the ability to study specific systemic features in isolation to better understand underlying mechanisms that lead to dysfunction. Here, we present a cardiac dysfunction model using angiotensin II (ANG II) to elicit pathological responses in a heart-on-a-chip platform that recapitulates native laminar cardiac tissue structure. Our platform, composed of arrays of muscular thin films (MTF), allows for functional comparisons of healthy and diseased tissues by tracking film deflections resulting from contracting tissues. To test our model, we measured gene expression profiles, morphological remodeling, calcium transients, and contractile stress generation in response to ANG II exposure and compared against previous experimental and clinical results. We found that ANG II induced pathological gene expression profiles including over-expression of natriuretic peptide B, Rho GTPase 1, and T-type calcium channels. ANG II exposure also increased proarrhythmic early after depolarization events and significantly reduced peak systolic stresses. Although ANG II has been shown to induce structural remodeling, we control tissue architecture via microcontact printing, and show pathological genetic profiles and functional impairment precede significant morphological changes. We assert that our in vitro model is a useful tool for evaluating tissue health and can serve as a platform for studying disease mechanisms and identifying novel therapeutics. PMID:26808388

  18. Angiotensin II Induced Cardiac Dysfunction on a Chip.

    PubMed

    Horton, Renita E; Yadid, Moran; McCain, Megan L; Sheehy, Sean P; Pasqualini, Francesco S; Park, Sung-Jin; Cho, Alexander; Campbell, Patrick; Parker, Kevin Kit

    2016-01-01

    In vitro disease models offer the ability to study specific systemic features in isolation to better understand underlying mechanisms that lead to dysfunction. Here, we present a cardiac dysfunction model using angiotensin II (ANG II) to elicit pathological responses in a heart-on-a-chip platform that recapitulates native laminar cardiac tissue structure. Our platform, composed of arrays of muscular thin films (MTF), allows for functional comparisons of healthy and diseased tissues by tracking film deflections resulting from contracting tissues. To test our model, we measured gene expression profiles, morphological remodeling, calcium transients, and contractile stress generation in response to ANG II exposure and compared against previous experimental and clinical results. We found that ANG II induced pathological gene expression profiles including over-expression of natriuretic peptide B, Rho GTPase 1, and T-type calcium channels. ANG II exposure also increased proarrhythmic early after depolarization events and significantly reduced peak systolic stresses. Although ANG II has been shown to induce structural remodeling, we control tissue architecture via microcontact printing, and show pathological genetic profiles and functional impairment precede significant morphological changes. We assert that our in vitro model is a useful tool for evaluating tissue health and can serve as a platform for studying disease mechanisms and identifying novel therapeutics.

  19. Homogeneity testing and quantitative analysis of manganese (Mn) in vitrified Mn-doped glasses by laser-induced breakdown spectroscopy (LIBS)

    SciTech Connect

    Unnikrishnan, V. K.; Nayak, Rajesh; Kartha, V. B.; Santhosh, C. E-mail: unnikrishnan.vk@manipal.edu; Sonavane, M. S.; Yeotikar, R. G.; Shah, M. L.; Gupta, G. P.; Suri, B. M.

    2014-09-15

    Laser-induced breakdown spectroscopy (LIBS), an atomic emission spectroscopy method, has rapidly grown as one of the best elemental analysis techniques over the past two decades. Homogeneity testing and quantitative analysis of manganese (Mn) in manganese-doped glasses have been carried out using an optimized LIBS system employing a nanosecond ultraviolet Nd:YAG laser as the source of excitation. The glass samples have been prepared using conventional vitrification methods. The laser pulse irradiance on the surface of the glass samples placed in air at atmospheric pressure was about 1.7×10{sup 9} W/cm{sup 2}. The spatially integrated plasma emission was collected and imaged on to the spectrograph slit using an optical-fiber-based collection system. Homogeneity was checked by recording LIBS spectra from different sites on the sample surface and analyzing the elemental emission intensities for concentration determination. Validation of the observed LIBS results was done by comparison with scanning electron microscope- energy dispersive X-ray spectroscopy (SEM-EDX) surface elemental mapping. The analytical performance of the LIBS system has been evaluated through the correlation of the LIBS determined concentrations of Mn with its certified values. The results are found to be in very good agreement with the certified concentrations.

  20. Metabolomics in angiotensin II-induced cardiac hypertrophy.

    PubMed

    Mervaala, Eero; Biala, Agnieszka; Merasto, Saara; Lempiäinen, Juha; Mattila, Ismo; Martonen, Essi; Eriksson, Ove; Louhelainen, Marjut; Finckenberg, Piet; Kaheinen, Petri; Muller, Dominik N; Luft, Friedrich C; Lapatto, Risto; Oresic, Matej

    2010-02-01

    Angiotensin II (Ang II) induces mitochondrial dysfunction. We tested whether Ang II alters the "metabolomic" profile. We harvested hearts from 8-week-old double transgenic rats harboring human renin and angiotensinogen genes (dTGRs) and controls (Sprague-Dawley), all with or without Ang II type 1 receptor (valsartan) blockade. We used gas chromatography coupled with time-of-flight mass spectrometry to detect 247 intermediary metabolites. We used a partial least-squares discriminate analysis and identified 112 metabolites that differed significantly after corrections (false discovery rate q <0.05). We found great differences in the use of fatty acids as an energy source, namely, decreased levels of octanoic, oleic, and linoleic acids in dTGR (all P<0.01). The increase in cardiac hypoxanthine levels in dTGRs suggested an increase in purine degradation, whereas other changes supported an increased ketogenic amino acid tyrosine level, causing energy production failure. The metabolomic profile of valsartan-treated dTGRs more closely resembled Sprague-Dawley rats than untreated dTGRs. Mitochondrial respiratory chain activity of cytochrome C oxidase was decreased in dTGRs, whereas complex I and complex II were unaltered. Mitochondria from dTGR hearts showed morphological alterations suggesting increased mitochondrial fusion. Cardiac expression of the redox-sensitive and the cardioprotective metabolic sensor sirtuin 1 was increased in dTGRs. Interestingly, valsartan changed the level of 33 metabolites and induced mitochondrial biogenesis in Sprague-Dawley rats. Thus, distinct patterns of cardiac substrate use in Ang II-induced cardiac hypertrophy are associated with mitochondrial dysfunction. The finding underscores the importance of Ang II in the regulation of mitochondrial biogenesis and cardiac metabolomics, even in healthy hearts.

  1. Visible light-induced formation of corrole-manganese(V)-oxo complexes: Observation of multiple oxidation pathways.

    PubMed

    Ka, Wai Kwong; Ngo, Fung Lee; Ranburger, Davis; Malone, Jonathan; Zhang, Rui

    2016-10-01

    Two manganese(V)-oxo corroles [Mn(V)(Cor)O] that differ in their electronic environments were produced by visible light irradiation of highly photo-labile corrole-manganese(IV) bromates. The corrole ligands under study include 5,10,15-tris(pentafluorophenyl)corrole (TPFC), and 5,10,15-triphenylcorrole (TPC). The kinetics of oxygen transfer atom (OAT) reactions with various organic reductants by these photo-generated Mn(V)(Cor)O were also studied in CH3CN and CH2Cl2 solutions. Mn(V)(Cor)O exhibits remarkable solvent and ligand effect on its reactivity and spectral behavior. In the more electron-deficient TPFC system and in the polar solvent CH3CN, Mn(V)(Cor)O returned Mn(III) corrole in the end of oxidation reactions. However, in the less polar solvent CH2Cl2 or in the less electron-deficient TPC system, Mn(IV) product was formed instead of Mn(III). Furthermore, with the same substrates and in the same solvent, the order of reactivity of Mn(V)(Cor)O was TPC>TPFC, which is inverted from that expected based on the electron-demand of corrole ligands. Our spectral and kinetic results in this study provide compelling evidence in favor of multiple oxidation pathways, where Mn(V)(Cor)O may serve as direct two-electron oxidant or undergo a disproportionation reaction to form a manganese(VI)-oxo corrole as the true oxidant. The choice of pathways is strongly dependent on the nature of the solvent and the corrole ligand.

  2. Blood-brain barrier flux of aluminum, manganese, iron and other metals suspected to contribute to metal-induced neurodegeneration.

    PubMed

    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

  3. Brain activation induced by voluntary alcohol and saccharin drinking in rats assessed with manganese-enhanced magnetic resonance imaging.

    PubMed

    Dudek, Mateusz; Abo-Ramadan, Usama; Hermann, Derik; Brown, Matthew; Canals, Santiago; Sommer, Wolfgang H; Hyytiä, Petri

    2015-11-01

    The neuroanatomical and neurochemical basis of alcohol reward has been studied extensively, but global alterations of neural activity in reward circuits during chronic alcohol use remain poorly described. Here, we measured brain activity changes produced by long-term voluntary alcohol drinking in the alcohol-preferring AA (Alko alcohol) rats using manganese-enhanced magnetic resonance imaging (MEMRI). MEMRI is based on the ability of paramagnetic manganese ions to accumulate in excitable neurons and thereby enhance the T1-weighted signal in activated brain areas. Following 6 weeks of voluntary alcohol drinking, AA rats were allowed to drink alcohol for an additional week, during which they were administered manganese chloride (MnCl2 ) with subcutaneous osmotic minipumps before MEMRI. A second group with an identical alcohol drinking history received MnCl2 during the abstinence week following alcohol drinking. For comparing alcohol with a natural reinforcer, MEMRI was also performed in saccharin-drinking rats. A water-drinking group receiving MnCl2 served as a control. We found that alcohol drinking increased brain activity extensively in cortical and subcortical areas, including the mesocorticolimbic and nigrostriatal dopamine pathways and their afferents. Remarkably similar activation maps were seen after saccharin ingestion. Particularly in the prelimbic cortex, ventral hippocampus and subthalamic nucleus, activation persisted into early abstinence. These data show that voluntary alcohol recruits an extensive network that includes the ascending dopamine systems and their afferent connections, and that this network is largely shared with saccharin reward. The regions displaying persistent alterations after alcohol drinking could participate in brain networks underlying alcohol seeking and relapse.

  4. Induced airflow in flying insects II. Measurement of induced flow.

    PubMed

    Sane, Sanjay P; Jacobson, Nathaniel P

    2006-01-01

    The flapping wings of insects and birds induce a strong flow over their body during flight. Although this flow influences the sensory biology and physiology of a flying animal, there are very little data on the characteristics of this self-generated flow field or its biological consequences. A model proposed in the companion paper estimated the induced flow over flying insects. In this study, we used a pair of hot wire anemometers to measure this flow at two locations near the body of a tethered flapping hawk moth, Manduca sexta. The axial inflow anemometer measured the airflow prior to its entry into the stroke plane, whereas the radial outflow anemometer measured the airflow after it crossed the stroke plane. The high temporal resolution of the hot wire anemometers allowed us to measure not only the mean induced flow but also subtle higher frequency disturbances occurring at 1-4 times the wing beat frequency. These data provide evidence for the predictions of a mathematical model proposed in the companion paper. Specifically, the absolute value of the measured induced flow matches the estimate of the model. Also, as predicted by the model, the induced flow varies linearly with wing beat frequency. Our experiments also show that wing flexion contributes significantly to the observed higher frequency disturbances. Thus, the hot wire anemometry technique provides a useful means to quantify the aerodynamic signature of wing flexion. The phasic and tonic components of induced flow influence several physiological processes such as convective heat loss and gas exchange in endothermic insects, as well as alter the nature of mechanosensory and olfactory stimuli to the sensory organs of a flying insect.

  5. CD38 promotes angiotensin II-induced cardiac hypertrophy.

    PubMed

    Guan, Xiao-Hui; Hong, Xuan; Zhao, Ning; Liu, Xiao-Hong; Xiao, Yun-Fei; Chen, Ting-Tao; Deng, Li-Bin; Wang, Xiao-Lei; Wang, Jian-Bin; Ji, Guang-Ju; Fu, Mingui; Deng, Ke-Yu; Xin, Hong-Bo

    2017-03-12

    Cardiac hypertrophy is an early hallmark during the clinical course of heart failure and regulated by various signalling pathways. Recently, we observed that mouse embryonic fibroblasts from CD38 knockout mice were significantly resistant to oxidative stress such as H2 O2 -induced injury and hypoxia/reoxygenation-induced injury. In addition, we also found that CD38 knockout mice protected heart from ischaemia reperfusion injury through activating SIRT1/FOXOs-mediated antioxidative stress pathway. However, the role of CD38 in cardiac hypertrophy is not explored. Here, we investigated the roles and mechanisms of CD38 in angiotensin II (Ang-II)-induced cardiac hypertrophy. Following 14 days of Ang-II infusion with osmotic mini-pumps, a comparable hypertension was generated in both of CD38 knockout and wild-type mice. However, the cardiac hypertrophy and fibrosis were much more severe in wild-type mice compared with CD38 knockout mice. Consistently, RNAi-induced knockdown of CD38 decreased the gene expressions of atrial natriuretic factor (ANF) and brain natriuretic peptide (BNP) and reactive oxygen species generation in Ang-II-stimulated H9c2 cells. In addition, the expression of SIRT3 was elevated in CD38 knockdown H9c2 cells, in which SIRT3 may further activate the FOXO3 antioxidant pathway. The intracellular Ca(2+) release induced by Ang-II markedly decreased in CD38 knockdown H9c2 cells, which might be associated with the decrease of nuclear translocation of NFATc4 and inhibition of ERK/AKT phosphorylation. We concluded that CD38 plays an essential role in cardiac hypertrophy probably via inhibition of SIRT3 expression and activation of Ca(2+) -NFAT signalling pathway. Thus, CD38 may be a novel target for treating cardiac hypertrophy.

  6. Identification and Characterization of a Putative Manganese Export Protein in Vibrio cholerae.

    PubMed

    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

  7. Association of exposure to manganese and iron with relaxation rates R1 and R2*- magnetic resonance imaging results from the WELDOX II study.

    PubMed

    Pesch, Beate; Dydak, Ulrike; Lotz, Anne; Casjens, Swaantje; Quetscher, Clara; Lehnert, Martin; Abramowski, Jessica; Stewig, Christoph; Yeh, Chien-Lin; Weiss, Tobias; van Thriel, Christoph; Herrmann, Lennard; Muhlack, Siegfried; Woitalla, Dirk; Glaubitz, Benjamin; Schmidt-Wilcke, Tobias; Brüning, Thomas

    2017-08-25

    Magnetic resonance imaging is a non-invasive method that allows the indirect quantification of manganese (Mn) and iron (Fe) accumulation in the brain due to their paramagnetic features. The WELDOX II study aimed to explore the influence of airborne and systemic exposure to Mn and Fe on the brain deposition using the relaxation rates R1 and R2* as biomarkers of metal accumulation in regions of interest in 161 men, including active and former welders. We obtained data on the relaxation rates R1 and R2* in regions that included structures within the globus pallidus (GP), substantia nigra (SN), and white matter of the frontal lobe (FL) of both hemispheres, as well as Mn in whole blood (MnB), and serum ferritin (SF). The study subjects, all male, included 48 active and 20 former welders, 41 patients with Parkinson's disease (PD), 13 patients with hemochromatosis (HC), and 39 controls. Respirable Mn and Fe were measured during a working shift for welders. Mixed regression models were applied to estimate the effects of MnB and SF on R1 and R2*. Furthermore, we estimated the influence of airborne Mn and Fe on the relaxation rates in active welders. MnB and SF were significant predictors of R1 but not of R2* in the GP, and were marginally associated with R1 in the SN (SF) and FL (MnB). Being a welder or suffering from PD or HC elicited no additional group effect on R1 or R2* beyond the effects of MnB and SF. In active welders, shift concentrations of respirable Mn>100μg/m(3) were associated with stronger R1 signals in the GP. In addition to the effects of MnB and SF, the welding technique had no further influence on R1. MnB and SF were significant predictors of R1 but not of R2*, indicative of metal accumulation, especially in the GP. Also, high airborne Mn concentration was associated with higher R1 signals in this brain region. The negative results obtained for being a welder or for the techniques with higher exposure to ultrafine particles when the blood

  8. Manganese nodules

    USGS Publications Warehouse

    Hein, James R.; Harff, Jan; Petersen, Sven; Thiede, Jorn

    2016-01-01

    The existence of manganese (Mn) nodules (Figure 1) has been known since the late 1800s when they were collected during the Challenger expedition of 1873–1876. However, it was not until after WWII that nodules were further studied in detail for their ability to adsorb metals from seawater. Many of the early studies did not distinguish Mn nodules from Mn crusts. Economic interest in Mn nodules began in the late 1950s and early 1960s when John Mero finished his Ph.D. thesis on this subject, which was published in the journal Economic Geology (Mero, 1962) and later as a book (Mero, 1965). By the mid-1970s, large consortia had formed to search for and mine Mn nodules that occur between the Clarion and Clipperton fracture zones (CCZ) in the NE Pacific (Figure 2). This is still the area considered of greatest economic potential in the global ocean because of high nickel (Ni), copper (Cu), and Mn contents and the dense distribution of nodules in the area. While the mining of nodules was fully expected to begin in the late 1970s or early 1980s, this never occurred due to a downturn in the price of metals on the global market. Since then, many research cruises have been undertaken to study the CCZ nodules, and now 15 contracts for exploration sites have been given or are pending by the International Seabed Authority (ISA). Many books and science journal articles have been published summarizing the early work (e.g., Baturin, 1988; Halbach et al., 1988), and research has continued to the present day (e.g., ISA, 1999; ISA, 2010). Although the initial attraction for nodules was their high Ni, Cu, and Mn contents, subsequent work has shown that nodules host large quantities of other critical metals needed for high-tech, green-tech, and energy applications (Hein et al., 2013; Hein and Koschinsky, 2014).

  9. Chronic manganese intoxication

    SciTech Connect

    Huang, C.C.; Chu, N.S.; Lu, C.S.; Wang, J.D.; Tsai, J.L.; Tzeng, J.L.; Wolters, E.C.; Calne, D.B. )

    1989-10-01

    We report six cases of chronic manganese intoxication in workers at a ferromanganese factory in Taiwan. Diagnosis was confirmed by assessing increased manganese concentrations in the blood, scalp, and pubic hair. In addition, increased manganese levels in the environmental air were established. The patients showed a bradykinetic-rigid syndrome indistinguishable from Parkinson's disease that responded to treatment with levodopa.

  10. Formation of manganese oxides by bacterially generated superoxide

    NASA Astrophysics Data System (ADS)

    Learman, D. R.; Voelker, B. M.; Vazquez-Rodriguez, A. I.; Hansel, C. M.

    2011-02-01

    Manganese oxide minerals are among the strongest sorbents and oxidants in the environment. The formation of these minerals controls the fate of contaminants, the degradation of recalcitrant carbon, the cycling of nutrients and the activity of anaerobic-based metabolisms. Oxidation of soluble manganese(II) ions to manganese(III/IV) oxides has been primarily attributed to direct enzymatic oxidation by microorganisms. However, the physiological reason for this process remains unknown. Here we assess the ability of a common species of marine bacteria-Roseobacter sp. AzwK-3b-to oxidize manganese(II) in the presence of chemical and biological inhibitors. We show that Roseobacter AzwK-3b oxidizes manganese(II) by producing the strong and versatile redox reactant superoxide. The oxidation of manganese(II), and concomitant production of manganese oxides, was inhibited in both the light and dark in the presence of enzymes and metals that scavenge superoxide. Oxidation was also inhibited by various proteases, enzymes that break down bacterial proteins, confirming that the superoxide was bacterially generated. We conclude that bacteria can oxidize manganese(II) indirectly, through the enzymatic generation of extracellular superoxide radicals. We suggest that dark bacterial production of superoxide may be a driving force in metal cycling and mineralization in the environment.

  11. Organ weight changes in mice after long-term inhalation exposure to manganese oxides nanoparticles

    NASA Astrophysics Data System (ADS)

    Zeman, T.; Buchtová, M.; Dočekal, B.; Míšek, I.; Navrátil, J.; Mikuška, P.; Šerý, O.; Večeřa, Z.

    2015-05-01

    Recently, it has been proven that manganese from inhaled particles of manganese compounds can accumulate in the internal organs of laboratory animals. Nevertheless, there were only a few researches dealing with changes in body morphology induced by inhalation of these particles, even though results of some studies indicate existence of such changes. The aim of our research was to assess the effect of inhaled manganese oxides nanoparticles on weight of internal organs. For this purpose a long-term inhalation experiment on laboratory mice was performed, during which the mice were exposed to MnO.Mn2O3 nanoparticles in concentration 2 × 106 particles/cm3 for 17 weeks, 24 hours a day, 7 days a week. Manganese oxides nanoparticles were synthesized continuously via aerosol route in a hot wall tube flow reactor using thermal decomposition of metal organic precursor manganese(II)acetylacetonate in the flow tube reactor at temperature 750 °C in the presence of 30 vol% of oxygen. It was proven that inhaled nanoparticles can influence the weight of internal organs of mice. Moreover, it was discovered that the resulting change in weight of selected organs is disproportional. The mice from the experimental group had statistically significantly lighter kidneys, liver and spleen and heavier pancreas compared to the mice from the control group.

  12. A seven-coordinated manganese(II) complex with V-shaped ligand bis(N-benzylbenzimidazol-2-ylmethyl)benzylamine: synthesis, structure, DNA-binding properties and antioxidant activities.

    PubMed

    Wu, Huilu; Yuan, Jingkun; Bai, Ying; Wang, Hua; Pan, Guolong; Kong, Jin

    2012-11-05

    A manganese(II) complex of the type, [MnL(pic)(2)]·H(2)O, was obtained by the reaction of the V-shaped ligand bis(N-benzylbenzimidazol-2-ylmethyl)benzylamine (L) with Mn(pic)(2) (pic=picrate). The ligand L and Mn(II) complex were confirmed on the basis of elemental analysis, molarconductivities, (1)H NMR, IR, UV-vis spectra and X-ray crystallography. Single-crystal X-ray revealed that central Mn(II) atom is seven-coordinate with a MnN(3)O(4) environment, in which ligand L acts as a tridentate N-donor. The remaining coordination sites were occupied by four O atoms afforded by two picrate anion. Interaction of the free ligand L and Mn(II) complex with DNA were investigated by spectrophotometric methods and viscosity measurements. The results suggested that both ligand L and Mn(II) complex bind to DNA in an intercalative binding mode, and DNA-binding affinity of the Mn(II) complex is stronger than that of ligand L. Moreover, antioxidant assay in vitro shows the Mn(II) complex possesses significant antioxidant activities.

  13. Manganese induced changes in growth, chlorophyll content and antioxidants activity in seedlings of broad bean (Vicia faba L.).

    PubMed

    Arya, Shashi K; Roy, B K

    2011-11-01

    The effect of manganese (Mn) on broad bean (Vicia faba L.) was studied with regard to growth, Mn accumulation in root and shoot, chlorophyll, proline content and peroxidase activity. Seeds were treated with Mn (10, 20, 40, 80,120,160 microM) and grown hydroponically up to 15 days. Manganese level in both root and shoot increased progressively in response to increasing concentration and it was high in roots (13 fold) overthe shoots (8 fold). The reductions in root (52%) and shoot (62.92%) development were evident for the maximum Mn concentration (160 microM). The chlorophyll amount gradually declined with increasing Mn concentrations and attained its maximum (42%) at 160 microM. By contrast, the guaiacol peroxidase activity was high (71%) along with the accompanying rise in proline content (75%) in shoots of the highest Mn concentration (160 microM). However, there was about 2 fold increase in total glutathione content at 40 microM than the basal level and further declined to 21.65 microg g(-1) fresh wt. at 160 microM Mn. The alterations in overall reflected Mn concentration-dependent changes in the parameters studied. The results suggest thatthe plant Vicia faba L. copes with Mn exposure through enhanced production of antioxidants.

  14. Angiotensin II induces cardiomyocyte hypertrophy probably through histone deacetylases.

    PubMed

    Lu, Ying; Yang, Shuang

    2009-09-01

    Angiotensin II (Ang II) plays a pathophysiological role in the genesis of cardiac hypertrophy as a hypertrophic stimulus. But little is known about the terminal steps, in which Ang II reprograms cardiac gene expression. Histone deacetyltransferases (HDACs) are considered as the integrators of divergent stress-response pathways during heart remodeling. However, the exact role of HDACs in the hypertrophic process is not clear yet. Therefore, we studied the expression of HDAC2, one of Class I HDACs, and the effect of valproic acid (VPA), a nonspecific HDAC inhibitor, in the Ang II-induced cardiomyocyte hypertrophy. Primary cultures of neonatal rat cardiomyocytes were prepared from 1-day-old Wistar rats and treated with Ang II. The mRNA levels of HDAC2 and beta-myosin heavy chain (beta-MHC), a hypertrophic marker gene, were determined by reverse transcription-polymerase chain reaction (RT-PCR). The protein expression of HDAC2 and c-fos, an immediate early response gene, was evaluated by immunohistochemistry, and the surface areas of cardiomyocytes were measured using Motic Images software. The expression levels of HDAC2 mRNA and protein were increased in a time-dependent manner during the hypertrophic process, accompanied with the increment of beta-MHC and c-fos proteins. Ang II also increased the surface area of cardiomyocytes by more than twofold. VPA significantly reversed these changes. These results suggest that Ang II may induce cardiomyocyte hypertrophy through HDACs in combination with c-fos and that VPA has the protective effect on cardiomyocyte hypertrophy. Thus, HDAC inhibition is a feasible therapeutic strategy that holds promise in the treatment of cardiac hypertrophy.

  15. Focused electron beam induced deposition of pure SIO II

    NASA Astrophysics Data System (ADS)

    Perentes, Alexandre; Hoffmann, Patrik; Munnik, Frans

    2007-02-01

    Focused electron beam induced processing (FEBID) equipments are the "all in one" tools for high resolution investigation, and modification of nano-devices. Focused electron beam induced deposition from a gaseous precursor usually results in a nano-composite sub-structured material, in which the interesting material is embedded in an amorphous carbonaceous matrix. Using the Hydrogen free tetraisocyanatosilane Si(NCO) 4 molecule as Si source, we show how a controlled oxygen flux, simultaneously injected with the precursor vapors, causes contaminants to vanish from the FEB deposits obtained and leads to the deposition of pure SiO II. The chemical composition of the FEBID material could be controlled from SiC IINO 3 to SiO II, the latter containing undetectable foreign element contamination. The [O II] / [TICS] ratio needed to obtain SiO II in our FEB deposition equipment is larger than 300. The evolution of the FEBID material chemical composition is presented as function of the [O II] / [TICS] molecular flux ratios. A hypothetical decomposition pathway of this silane under these conditions is discussed based on the different species formed under electron bombardment of TICS. Transmission electron microscopy investigations demonstrated that the deposited oxide is smooth (roughness sub 2nm) and amorphous. Infrared spectroscopy confirmed the low concentration of hydroxyl groups. The Hydrogen content of the deposited oxide, measured by elastic recoil detection analysis, is as low as 1 at%. 193nm wavelength AIMS investigations of 125nm thick SiO II pads (obtained with [O II] / [TICS] = 325) showed an undetectable light absorption.

  16. The S3 state of photosystem II: differences between the structure of the manganese complex in the S2 and S3 states determined by X-ray absorption spectroscopy.

    PubMed

    Guiles, R D; Zimmermann, J L; McDermott, A E; Yachandra, V K; Cole, J L; Dexheimer, S L; Britt, R D; Wieghardt, K; Bossek, U; Sauer, K

    1990-01-16

    O2-evolving photosystem II (PSII) membranes from spinach have been cryogenically stabilized in the S3 state of the oxygen-evolving complex. The cryogenic trapping of the S3 state was achieved using a double-turnover illumination of dark-adapted PSII preparations maintained at 240 K. A double turnover of PSII was accomplished using the high-potential acceptor, Q400, which is the high-spin iron of the iron-quinone acceptor complex. EPR spectroscopy was the principal tool establishing the S-state composition and defining the electron-transfer events associated with a double turnover of PSII. The inflection point energy of the Mn X-ray absorption K-edge of PSII preparations poised in the S3 state is the same as for those poised in the S2 state. This is surprising in light of the loss of the multiline EPR signal upon advancing to the S3 state. This indicates that the oxidative equivalent stored within the oxygen-evolving complex (OEC) during this transition resides on another intermediate donor which must be very close to the manganese complex. An analysis of the Mn extended X-ray absorption fine structure (EXAFS) of PSII preparations poised in the S2 and S3 states indicates that a small structural rearrangement occurs during this photoinduced transition. A detailed comparison of the Mn EXAFS of these two S states with the EXAFS of four multinuclear mu-oxo-bridged manganese compounds indicates that the photosynthetic manganese site most probably consists of a pair of binuclear di-mu-oxo-bridged manganese structures. However, we cannot rule out, on the basis of the EXAFS analysis alone, a complex containing a mononuclear center and a linear trinuclear complex. The subtle differences observed between the S states are best explained by an increase in the spread of Mn-Mn distances occurring during the S2----S3 state transition. This increased disorder in the manganese distances suggests the presence of two inequivalent di-mu-oxo-bridged binuclear structures in the S3 state.

  17. Manganese Potentiates LPS-Induced Heme-Oxygenase 1 in Microglia but not Dopaminergic Cells: Role in Controlling Microglial Hydrogen Peroxide and Inflammatory Cytokine Output

    PubMed Central

    Dodd, Celia A.; Filipov, Nikolay M.

    2012-01-01

    Excessive manganese (Mn) exposure increases output of glial-derived inflammatory products, which may indirectly contribute to the neurotoxic effects of this essential metal. In microglia, Mn increases hydrogen peroxide (H2O2) release and potentiates lipopolysaccharide (LPS)-induced cytokines (TNF-α, IL-6) and nitric oxide (NO). Inducible heme-oxygenase (HO-1) plays a role in the regulation of inflammation and its expression is upregulated in response to oxidative stressors, including metals and LPS. Because Mn can oxidatively affect neurons both directly and indirectly, we investigated the effect of Mn exposure on the induction of HO-1 in resting and LPS-activated microglia (N9) and dopaminergic neurons (N27). In microglia, 24 h exposure to Mn (up to 250 μM) had minimal effects on its own, but it markedly potentiated LPS (100 ng/ml)-induced HO-1protein and mRNA. Inhibition of microglial HO-1 activity with two different inhibitors indicated that HO-1 is a positive regulator of the Mn-potentiated cytokine output and a negative regulator of the Mn-induced H2O2 output. Mn enhancement of LPS-induced HO-1 does not appear to be dependent on H2O2 or NO, as Mn+LPS-induced H2O2 release was not greater than the increase induced by Mn alone and inhibition of iNOS did not change Mn potentiation of HO-1. However, because Mn exposure potentiated the LPS-induced nuclear expression of small Maf proteins, this may be one mechanism Mn uses to affect the expression of HO-1 in activated microglia. Finally, the potentiating effects of Mn on HO-1 appear to be glia-specific for Mn, LPS, or Mn+LPS did not induce HO-1 in N27 neuronal cells. PMID:21963524

  18. A 21-amino acid peptide from the cysteine cluster II of the family D DNA polymerase from Pyrococcus horikoshii stimulates its nuclease activity which is Mre11-like and prefers manganese ion as the cofactor.

    PubMed

    Shen, Yulong; Tang, Xiao-Feng; Yokoyama, Hideshi; Matsui, Eriko; Matsui, Ikuo

    2004-01-01

    Family D DNA polymerase (PolD) is a new type of DNA polymerase possessing polymerization and 3'-5' exonuclease activities. Here we report the characterization of the nuclease activity of PolD from Pyrococcus horikoshii. By site-directed mutagenesis, we verified that the putative Mre11-like nuclease domain in the small subunit (DP1), predicted according to computer analysis and structure inference reported previously, is the catalytic domain. We show that D363, H365 and H454 are the essential residues, while D407, N453, H500, H563 and H565 are critical residues for the activity. We provide experimental evidence demonstrating that manganese, rather than magnesium, is the preferable metal ion for the nuclease activity of PolD. We also show that DP1 alone is insufficient to perform full catalysis, which additionally requires the formation of the PolD complex and manganese ion. We found that a 21 amino acid, subunit-interacting peptide of the sequence from cysteine cluster II of the large subunit (DP2) stimulates the exonuclease activity of DP1 and the internal deletion mutants of PolD lacking the 21-aa sequence. This indicates that the putative zinc finger motif of the cysteine cluster II is deeply involved in the nucleolytic catalysis.

  19. A 21-amino acid peptide from the cysteine cluster II of the family D DNA polymerase from Pyrococcus horikoshii stimulates its nuclease activity which is Mre11-like and prefers manganese ion as the cofactor

    PubMed Central

    Shen, Yulong; Tang, Xiao-Feng; Yokoyama, Hideshi; Matsui, Eriko; Matsui, Ikuo

    2004-01-01

    Family D DNA polymerase (PolD) is a new type of DNA polymerase possessing polymerization and 3′–5′ exonuclease activities. Here we report the characterization of the nuclease activity of PolD from Pyrococcus horikoshii. By site-directed mutagenesis, we verified that the putative Mre11-like nuclease domain in the small subunit (DP1), predicted according to computer analysis and structure inference reported previously, is the catalytic domain. We show that D363, H365 and H454 are the essential residues, while D407, N453, H500, H563 and H565 are critical residues for the activity. We provide experimental evidence demonstrating that manganese, rather than magnesium, is the preferable metal ion for the nuclease activity of PolD. We also show that DP1 alone is insufficient to perform full catalysis, which additionally requires the formation of the PolD complex and manganese ion. We found that a 21 amino acid, subunit-interacting peptide of the sequence from cysteine cluster II of the large subunit (DP2) stimulates the exonuclease activity of DP1 and the internal deletion mutants of PolD lacking the 21-aa sequence. This indicates that the putative zinc finger motif of the cysteine cluster II is deeply involved in the nucleolytic catalysis. PMID:14704353

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

    PubMed

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

    2016-04-19

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

  1. Manganese(II)-azido/thiocyanato complexes of naphthylazoimidazoles: X-ray structures of Mn(β-NaiEt) 2(X) 2 (β-NaiEt = 1-ethyl-2-(naphthyl-β-azo)imidazole; X=N3-, NCS -)

    NASA Astrophysics Data System (ADS)

    Das, D.; Chand, B. G.; Wu, J. S.; Lu, T.-H.; Sinha, C.

    2007-10-01

    Manganese(II)-naphthylazoimidazole complexes using N3- and NCS - as counter ions are characterized as Mn(β-NaiR) 2(X) 2(β-NaiEt = 1-alkyl-2-(naphthyl-β-azo)imidazole; X=N3-, NCS -). The ligands are unsymmetric N(imidazole), N(azo) chelating agents. The microanalytical, spectral (FT-IR, UV-vis), magnetic (bulk moment and EPR) and electrochemical data establish the structure and composition of the complexes. The single crystal X-ray diffraction studies of Mn(β-NaiEt) 2(N 3) 2 and Mn(β-NaiEt) 2(NCS) 2(β-NaiEt = 1-ethyl-2-(naphthyl-β-azo)imidazole) have confirmed the three dimensional structure of the complexes. Cyclic voltammetry exhibits high potential Mn(III)/Mn(II) couple along with azo reductions. The EPR spectra show usual pattern.

  2. Evodiamine inhibits angiotensin II-induced rat cardiomyocyte hypertrophy.

    PubMed

    He, Na; Gong, Qi-Hai; Zhang, Feng; Zhang, Jing-Yi; Lin, Shu-Xian; Hou, Hua-Hua; Wu, Qin; Sun, An-Sheng

    2017-09-05

    To investigate the effects of evodiamine (Evo), a component of Evodiaminedia rutaecarpa Juss.) Benth, on cardiomyocyte hypertrophy induced by angiotensin II (Ang II) and further explore the potential mechanisms. Cardiomyocytes from neonatal Sprague Dawley rats were isolated and characterized, and then the cadiomyocyte cultures were randomly divided into control, model (Ang II 0.1 μmol/L), and Evo (0.03, 0.3, 3 μmol/L) groups. The cardiomyocyte surface area, protein level, intracellular free calcium ([Ca(2+)]i) concentration, activity of nitric oxide synthase (NOS) and content of nitric oxide (NO) were measured, respectively. The mRNA expressions of atrial natriuretic factor (ANF), calcineurin (CaN), extracellular signal-regulated kinase-2 (ERK-2), and endothelial nitric oxide synthase (eNOS) of cardiomyocytes were analyzed by real-time reverse transcriptionpolymerase chain reaction. The protein expressions of calcineurin catalytic subunit (CnA) and mitogen-activated protein kinase phosphatase-1 (MKP-1) were detected by Western blot analysis. Compared with the control group, Ang II induced cardiomyocytes hypertrophy, as evidenced by increased cardiomyocyte surface area, protein content, and ANF mRNA expression; increased intracellular free calcium ([Ca(2+)]i) concentration and expressions of CaN mRNA, CnA protein, and ERK-2 mRNA, but decreased MKP-1 protein expression (P<0.05 or P<0.01). Compared with Ang II, Evo (0.3, 3 μmol/L) significantly attenuated Ang II-induced cardiomyocyte hypertrophy, decreased the [Ca(2+)]i concentration and expressions of CaN mRNA, CnA protein, and ERK-2 mRNA, but increased MKP-1 protein expression (P<0.05 or P<0.01). Most interestingly, Evo increased the NOS activity and NO production, and upregulated the eNOS mRNA expression (P<0.05). Evo signifificantly attenuated Ang II-induced cardiomyocyte hypertrophy, and this effect was partly due to promotion of NO production, reduction of [Ca(2+)]i concentration, and inhibition of CaN and

  3. Beneficial effects of astragaloside IV against angiotensin II-induced mitochondrial dysfunction in rat vascular smooth muscle cells

    PubMed Central

    LU, YAO; LI, SU; WU, HENGFANG; BIAN, ZHIPING; XU, JINDAN; GU, CHUNRONG; CHEN, XIANGJIAN; YANG, DI

    2015-01-01

    Angiotensin II (Ang II)-induced mitochondrial dysfunction is a prominent characteristic of the majority of cardiovascular diseases. Astragaloside IV (As-IV), the major active ingredient of Astragalus membranaceus (Fisch.) Bge. (a traditional Chinese herbal medicine), possesses antioxidant properties. The present study was carried out to examine whether As-IV can reverse Ang II-induced mitochondrial dysfunction in vascular smooth muscle cells (VSMCs) and to elucidate the underlying molecular mechanisms. Cultured rat aortic VSMCs treated with Ang II (1 µM) for 24 h exhibited mitochondrial dysfunction, including a decrease in mitochondrial oxygen consumption rates (OCRs), adenosine triphosphate (ATP) production and mitochondrial DNA (mtDNA) levels, as well as the disruption of mitochondrial structural integrity. Following treatment with Ang II, As-IV (50 µg/ml) was added to the culture medium followed by incubation for a further 24 h. The administration of As-IV significantly increased the mitochondrial OCRs, ATP production and the mtDNA levels, and reversed the mitochondrial morphological changes which occurred in the VSMCs. Treatment with As-IV also reversed the Ang II-induced increase in the production of reactive oxygen species (ROS), the increase in NADPH oxidase and xanthine oxidase activity, as well as the decrease in mitochondrial membrane potential (ΔΨm) and manganese superoxide dismutase (Mn-SOD) activity. Furthermore, treatment with As-IV led to an increase in the mRNA expression of peroxisome proliferator-activated receptor-gamma coactivator-1α (PGC-1α) and mitochondrial transcription factor A (Tfam), and in the protein expression of PGC-1α, parkin and dynamin 1-like protein 1 (Drp1) in the VSMCs. These results indicate that As-IV exerts beneficial effects on Ang II-induced mitochondrial dysfunction in rat VSMCs and that these effects are mediated through the inhibition of ROS overproduction, as well as the promotion of mitochondrial autophagy and

  4. Efficient manganese luminescence induced by Ce3+-Mn2+ energy transfer in rare earth fluoride and phosphate nanocrystals

    PubMed Central

    2011-01-01

    Manganese materials with attractive optical properties have been proposed for applications in such areas as photonics, light-emitting diodes, and bioimaging. In this paper, we have demonstrated multicolor Mn2+ luminescence in the visible region by controlling Ce3+-Mn2+ energy transfer in rare earth nanocrystals [NCs]. CeF3 and CePO4 NCs doped with Mn2+ have been prepared and can be well dispersed in aqueous solutions. Under ultraviolet light excitation, both the CeF3:Mn and CePO4:Mn NCs exhibit Mn2+ luminescence, yet their output colors are green and orange, respectively. By optimizing Mn2+ doping concentrations, Mn2+ luminescence quantum efficiency and Ce3+-Mn2+ energy transfer efficiency can respectively reach 14% and 60% in the CeF3:Mn NCs. PMID:21711641

  5. Manganese Oxidation State Assignment for Manganese Catalase.

    PubMed

    Beal, Nathan J; O'Malley, Patrick J

    2016-04-06

    The oxidation state assignment of the manganese ions present in the superoxidized manganese (III/IV) catalase active site is determined by comparing experimental and broken symmetry density functional theory calculated (14)N, (17)O, and (1)H hyperfine couplings. Experimental results have been interpreted to indicate that the substrate water is coordinated to the Mn(III) ion. However, by calculating hyperfine couplings for both scenarios we show that water is coordinated to the Mn(IV) ion and that the assigned oxidation states of the two manganese ions present in the site are the opposite of that previously proposed based on experimental measurements alone.

  6. Protective role of quercetin against manganese-induced injury in the liver, kidney, and lung; and hematological parameters in acute and subchronic rat models.

    PubMed

    Bahar, Entaz; Lee, Geum-Hwa; Bhattarai, Kashi Raj; Lee, Hwa-Young; Kim, Hyun-Kyoung; Handigund, Mallikarjun; Choi, Min-Kyung; Han, Sun-Young; Chae, Han-Jung; Yoon, Hyonok

    2017-01-01

    Manganese (Mn) is an important mineral element required in trace amounts for development of the human body, while over- or chronic-exposure can cause serious organ toxicity. The current study was designed to evaluate the protective role of quercetin (Qct) against Mn-induced toxicity in the liver, kidney, lung, and hematological parameters in acute and subchronic rat models. Male Sprague Dawley rats were divided into control, Mn (100 mg/kg for acute model and 15 mg/kg for subchronic model), and Mn + Qct (25 and 50 mg/kg) groups in both acute and subchronic models. Our result revealed that Mn + Qct groups effectively reduced Mn-induced ALT, AST, and creatinine levels. However, Mn + Qct groups had effectively reversed Mn-induced alteration of complete blood count, including red blood cells, hemoglobin, hematocrit, mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, platelets, and white blood cells. Meanwhile, the Mn + Qct groups had significantly decreased neutrophil and eosinophil and increased lymphocyte levels relative to the Mn group. Additionally, Mn + Qct groups showed a beneficial effect against Mn-induced macrophages and neutrophils. Our result demonstrated that Mn + Qct groups exhibited protective effects on Mn-induced alteration of GRP78, CHOP, and caspase-3 activities. Furthermore, histopathological observation showed that Mn + Qct groups effectively counteracted Mn-induced morphological change in the liver, kidney, and lung. Moreover, immunohistochemically Mn + Qct groups had significantly attenuated Mn-induced 8-oxo-2'-deoxyguanosine immunoreactivity. Our study suggests that Qct could be a substantially promising organ-protective agent against toxic Mn effects and perhaps against other toxic metal chemicals or drugs.

  7. Angiotensin II infusion induces marked diaphragmatic skeletal muscle atrophy.

    PubMed

    Rezk, Bashir M; Yoshida, Tadashi; Semprun-Prieto, Laura; Higashi, Yusuke; Sukhanov, Sergiy; Delafontaine, Patrice

    2012-01-01

    Advanced congestive heart failure (CHF) and chronic kidney disease (CKD) are characterized by increased angiotensin II (Ang II) levels and are often accompanied by significant skeletal muscle wasting that negatively impacts mortality and morbidity. Both CHF and CKD patients have respiratory muscle dysfunction, however the potential effects of Ang II on respiratory muscles are unknown. We investigated the effects of Ang II on diaphragm muscle in FVB mice. Ang II induced significant diaphragm muscle wasting (18.7±1.6% decrease in weight at one week) and reduction in fiber cross-sectional area. Expression of the E3 ubiquitin ligases atrogin-1 and muscle ring finger-1 (MuRF-1) and of the pro-apoptotic factor BAX was increased after 24 h of Ang II infusion (4.4±0.3 fold, 3.1±0.5 fold and 1.6±0.2 fold, respectively, compared to sham infused control) suggesting increased muscle protein degradation and apoptosis. In Ang II infused animals, there was significant regeneration of injured diaphragm muscles at 7 days as indicated by an increase in the number of myofibers with centralized nuclei and high expression of embryonic myosin heavy chain (E-MyHC, 11.2±3.3 fold increase) and of the satellite cell marker M-cadherin (59.2±22.2% increase). Furthermore, there was an increase in expression of insulin-like growth factor-1 (IGF-1, 1.8±0.3 fold increase) in Ang II infused diaphragm, suggesting the involvement of IGF-1 in diaphragm muscle regeneration. Bone-marrow transplantation experiments indicated that although there was recruitment of bone-marrow derived cells to the injured diaphragm in Ang II infused mice (267.0±74.6% increase), those cells did not express markers of muscle stem cells or regenerating myofibers. In conclusion, Ang II causes marked diaphragm muscle wasting, which may be important for the pathophysiology of respiratory muscle dysfunction and cachexia in conditions such as CHF and CKD.

  8. Manganese superoxide dismutase interacts with a large scale of cellular and mitochondrial proteins in low dose radiation-induced adaptive radioprotection

    PubMed Central

    Eldridge, Angela; Fan, Ming; Woloschak, Gayle; Grdina, David J.; Chromy, Brett A.; Li, Jian Jian

    2012-01-01

    Cellular adaptive response to certain low level genotoxic stresses including the exposure to low dose ionizing radiation (LDIR) shows promise as a tool to enhance radioprotection in normal cells but not in tumor cells. Manganese superoxide dismutase (MnSOD), a fundamental mitochondrial antioxidant in mammalian cells plays a key role in LDIR-induced adaptive response. In this study, we aim to elucidate the signaling network associated with the MnSOD-induced radiation protection. A MnSOD-interacting protein profile was established in LDIR-treated human skin cells. Human skin keratinocytes (HK18) were irradiated with a single dose LDIR (10 cGy x-ray) and the cell lysates were immunoprecipitated using α-MnSOD and applied to two different gel-based proteomics followed by mass spectrometry for protein identification. Analysis of the profiles of MnSOD interacting partners before and after LDIR detected different patterns of MnSOD protein-protein interactions in response to LDIR. Interestingly, many of the MnSOD interacting proteins are known to have functions related to mitochondrial regulations on cell metabolism, apoptosis and DNA repair. These results provide the evidence indicating that in addition to the enzymatic action detoxifying superoxide, the antioxidant MnSOD may function as a signaling regulator in stress induced adaptive protection through cell survival pathways. PMID:23000060

  9. The role of NLRP3-CASP1 in inflammasome-mediated neuroinflammation and autophagy dysfunction in manganese-induced, hippocampal-dependent impairment of learning and memory ability.

    PubMed

    Wang, Diya; Zhang, Jianbin; Jiang, Wenkai; Cao, Zipeng; Zhao, Fang; Cai, Tongjian; Aschner, Michael; Luo, Wenjing

    2017-02-27

    Central nervous system (CNS) inflammation and autophagy dysfunction are known to be involved in the pathology of neurodegenerative diseases. Manganese (Mn), a neurotoxic metal, has the potential to induce microglia-mediated neuroinflammation as well as autophagy dysfunction. NLRP3 (NLR family, pyrin domain containing 3)- CASP1 (caspase 1) inflammasome-mediated neuroinflammation in microglia has specific relevance to neurological diseases. However, the mechanism driving these phenomena remains poorly understood. We demonstrate that Mn activates the NLRP3-CASP1 inflammasome pathway in the hippocampus of mice and BV2 cells by triggering autophagy-lysosomal dysfunction. The autophagy-lysosomal dysfunction is induced by lysosomal damage caused by excessive Mn accumulation, damaging the structure and normal function of these organelles. Additionally, we show that the release of lysosomal CTSB (cathepsin B) plays an important role in Mn-induced NLRP3-CASP1 inflammasome activation, and that the increased autophagosomes in the cytoplasm are not the main cause of NLRP3-CASP1 inflammasome activation. The accumulation of proinflammatory cytokines, such as IL1B (interleukin 1 β) and IL18 (interleukin 18), as well as the dysfunctional autophagy pathway may damage hippocampal neuronal cells, thus leading to hippocampal-dependent impairment in learning and memory, which is associated with the pathogenesis of Alzheimer disease (AD).

  10. Manganese superoxide dismutase interacts with a large scale of cellular and mitochondrial proteins in low-dose radiation-induced adaptive radioprotection.

    PubMed

    Eldridge, Angela; Fan, Ming; Woloschak, Gayle; Grdina, David J; Chromy, Brett A; Li, Jian Jian

    2012-11-15

    The cellular adaptive response to certain low-level genotoxic stresses, including exposure to low-dose ionizing radiation (LDIR), shows promise as a tool to enhance radioprotection in normal cells but not in tumor cells. Manganese superoxide dismutase (MnSOD), a fundamental mitochondrial antioxidant in mammalian cells, plays a key role in the LDIR-induced adaptive response. In this study, we aimed to elucidate the signaling network associated with MnSOD-induced radiation protection. A MnSOD-interacting protein profile was established in LDIR-treated human skin cells. Human skin keratinocytes (HK18) were irradiated with a single dose of LDIR (10 cGy X-ray) and the cell lysates were immunoprecipitated using α-MnSOD and applied to two different gel-based proteomic experiments followed by mass spectrometry for protein identification. Analysis of the profiles of MnSOD-interacting partners before and after LDIR detected various patterns of MnSOD protein-protein interactions in response to LDIR. Interestingly, many of the MnSOD-interacting proteins are known to have functions related to mitochondrial regulation of cell metabolism, apoptosis, and DNA repair. These results provide evidence indicating that in addition to the enzymatic action of detoxifying superoxide, the antioxidant MnSOD may function as a signaling regulator in stress-induced adaptive protection through cell survival pathways. Copyright © 2012 Elsevier Inc. All rights reserved.

  11. Multireversible redox processes in pentanuclear bis(triple-helical) manganese complexes featuring an oxo-centered triangular {Mn(II)2Mn(III)(μ3-O)}5+ or {Mn(II)Mn(III)2(μ3-O)}6+ core wrapped by two {Mn(II)2(bpp)3}-.

    PubMed

    Romain, Sophie; Rich, Jordi; Sens, Cristina; Stoll, Thibaut; Benet-Buchholz, Jordi; Llobet, Antoni; Rodriguez, Montserrat; Romero, Isabel; Clérac, Rodolphe; Mathonière, Corine; Duboc, Carole; Deronzier, Alain; Collomb, Marie-Noëlle

    2011-09-05

    A new pentanuclear bis(triple-helical) manganese complex has been isolated and characterized by X-ray diffraction in two oxidation states: [{Mn(II)(μ-bpp)(3)}(2)Mn(II)(2)Mn(III)(μ-O)](3+) (1(3+)) and [{Mn(II)(μ-bpp)(3)}(2)Mn(II)Mn(III)(2)(μ-O)](4+) (1(4+)). The structure consists of a central {Mn(3)(μ(3)-O)} core of Mn(II)(2)Mn(III) (1(3+)) or Mn(II)Mn(III)(2) ions (1(4+)) which is connected to two apical Mn(II) ions through six bpp(-) ligands. Both cations have a triple-stranded helicate configuration, and a pair of enantiomers is present in each crystal. The redox properties of 1(3+) have been investigated in CH(3)CN. A series of five distinct and reversible one-electron waves is observed in the -1.0 and +1.50 V potential range, assigned to the Mn(II)(4)Mn(III)/Mn(II)(5), Mn(II)(3)Mn(III)(2)/Mn(II)(4)Mn(III), Mn(II)(2)Mn(III)(3)/Mn(II)(3)Mn(III)(2), Mn(II)Mn(III)(4)/Mn(II)(2)Mn(III)(3), and Mn(III)(5)/Mn(II)Mn(III)(4) redox couples. The two first oxidation processes leading to Mn(II)(3)Mn(III)(2) (1(4+)) and Mn(II)(2)Mn(III)(3) (1(5+)) are related to the oxidation of the Mn(II) ions of the central core and the two higher oxidation waves, close in potential, are thus assigned to the oxidation of the two apical Mn(II) ions. The 1(4+) and 1(5+) oxidized species and the reduced Mn(4)(II) (1(2+)) species are quantitatively generated by bulk electrolyses demonstrating the high stability of the pentanuclear structure in four oxidation states (1(2+) to 1(5+)). The spectroscopic characteristics (X-band electron paramagnetic resonance, EPR, and UV-visible) of these species are also described as well as the magnetic properties of 1(3+) and 1(4+) in solid state. The powder X- and Q-band EPR signature of 1(3+) corresponds to an S = 5/2 spin state characterized by a small zero-field splitting parameter (|D| = 0.071 cm(-1)) attributed to the two apical Mn(II) ions. At 40 K, the magnetic behavior is consistent for 1(3+) with two apical S = 5/2 {Mn(II)(bpp)(3)}(-) and one S

  12. Manganese uptake of imprinted polymers

    SciTech Connect

    Susanna Ventura

    2015-09-30

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

  13. Polyphenolic Extract of Euphorbia supina Attenuates Manganese-Induced Neurotoxicity by Enhancing Antioxidant Activity through Regulation of ER Stress and ER Stress-Mediated Apoptosis.

    PubMed

    Bahar, Entaz; Lee, Geum-Hwa; Bhattarai, Kashi Raj; Lee, Hwa-Young; Choi, Min-Kyung; Rashid, Harun-Or; Kim, Ji-Ye; Chae, Han-Jung; Yoon, Hyonok

    2017-01-30

    Manganese (Mn) is an important trace element present in human body, which acts as an enzyme co-factor or activator in various metabolic reactions. While essential in trace amounts, excess levels of Mn in human brain can produce neurotoxicity, including idiopathic Parkinson's disease (PD)-like extrapyramidal manganism symptoms. This study aimed to investigate the protective role of polyphenolic extract of Euphorbia supina (PPEES) on Mn-induced neurotoxicity and the underlying mechanism in human neuroblastoma SKNMC cells and Sprague-Dawley (SD) male rat brain. PPEES possessed significant amount of total phenolic and flavonoid contents. PPEES also showed significant antioxidant activity in 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging and reducing power capacity (RPC) assays. Our results showed that Mn treatment significantly reduced cell viability and increased lactate dehydrogenase (LDH) level, which was attenuated by PPEES pretreatment at 100 and 200 µg/mL. Additionally, PPEES pretreatment markedly attenuated Mn-induced antioxidant status alteration by resolving the ROS, MDA and GSH levels and SOD and CAT activities. PPEES pretreatment also significantly attenuated Mn-induced mitochondrial membrane potential (ΔΨm) and apoptosis. Meanwhile, PPEES pretreatment significantly reversed the Mn-induced alteration in the GRP78, GADD34, XBP-1, CHOP, Bcl-2, Bax and caspase-3 activities. Furthermore, administration of PPEES (100 and 200 mg/kg) to Mn exposed rats showed improvement of histopathological alteration in comparison to Mn-treated rats. Moreover, administration of PPEES to Mn exposed rats showed significant reduction of 8-OHdG and Bax immunoreactivity. The results suggest that PPEES treatment reduces Mn-induced oxidative stress and neuronal cell loss in SKNMC cells and in the rat brain. Therefore, PPEES may be considered as potential treat-ment in Mn-intoxicated patients.

  14. Rebamipide attenuates nonsteroidal anti-inflammatory drugs (NSAID) induced lipid peroxidation by the manganese superoxide dismutase (MnSOD) overexpression in gastrointestinal epithelial cells.

    PubMed

    Nagano, Y; Matsui, H; Shimokawa, O; Hirayama, A; Tamura, M; Nakamura, Y; Kaneko, T; Rai, K; Indo, H P; Majima, H J; Hyodo, I

    2012-04-01

    Nonsteroidal anti-inflammatory drugs (NSAIDs) often cause gastrointestinal complications such as gastric ulcers and erosions. Recent studies on the pathogenesis have revealed that NSAIDs induce lipid peroxidation in gastric epithelial cells by generating superoxide anion in mitochondria, independently with cyclooxygenase-inhibition and the subsequent prostaglandin deficiency. Although not clearly elucidated, the impairment of mitochondrial oxidative phosphorylation, or uncoupling, by NSAIDs is associated with the generation of superoxide anion. Physiologically, superoxide is immediately transformed into hydrogen peroxide and diatomic oxygen with manganese superoxide dismutase (MnSOD). Rebamipide is an antiulcer agent that showed protective effects against NSAID-induced lipid peroxidation in gastrointestinal tracts. We hypothesized that rebamipide may attenuate lipid peroxidation by increasing the expression of MnSOD protein in mitochondria and decreasing the leakage of superoxide anion in NSAID-treated gastric and small intestinal epithelial cells. Firstly, to examine rebamipide increases the expression of MnSOD proteins in mitochondria of gastrointestinal epithelial cells, we underwent Western blotting analysis against anti-MnSOD antibody in gastric RGM1 cells and small intestinal IEC6 cells. Secondly, to examine whether the pretreatment of rebamipide decreases NSAID-induced mitochondrial impairment and lipid peroxidation, we treated these cells with NSAIDs with or without rebamipide pretreatment, and examined with specific fluorescent indicators. Finally, to examine whether pretreatment of rebamipide attenuates NSAID-induced superoxide anion leakage from mitochondria, we examined the mitochondria from indomethacin-treated RGM1 cells with electron spin resonance (ESR) spectroscopy using a specific spin-trapping reagent, CYPMPO. Rebamipide increased the expression of MnSOD protein, and attenuated NSAID-induced mitochondrial impairment and lipid peroxidation in RGM1

  15. Polyphenolic Extract of Euphorbia supina Attenuates Manganese-Induced Neurotoxicity by Enhancing Antioxidant Activity through Regulation of ER Stress and ER Stress-Mediated Apoptosis

    PubMed Central

    Bahar, Entaz; Lee, Geum-Hwa; Bhattarai, Kashi Raj; Lee, Hwa-Young; Choi, Min-Kyung; Rashid, Harun-Or; Kim, Ji-Ye; Chae, Han-Jung; Yoon, Hyonok

    2017-01-01

    Manganese (Mn) is an important trace element present in human body, which acts as an enzyme co-factor or activator in various metabolic reactions. While essential in trace amounts, excess levels of Mn in human brain can produce neurotoxicity, including idiopathic Parkinson’s disease (PD)-like extrapyramidal manganism symptoms. This study aimed to investigate the protective role of polyphenolic extract of Euphorbia supina (PPEES) on Mn-induced neurotoxicity and the underlying mechanism in human neuroblastoma SKNMC cells and Sprague-Dawley (SD) male rat brain. PPEES possessed significant amount of total phenolic and flavonoid contents. PPEES also showed significant antioxidant activity in 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging and reducing power capacity (RPC) assays. Our results showed that Mn treatment significantly reduced cell viability and increased lactate dehydrogenase (LDH) level, which was attenuated by PPEES pretreatment at 100 and 200 µg/mL. Additionally, PPEES pretreatment markedly attenuated Mn-induced antioxidant status alteration by resolving the ROS, MDA and GSH levels and SOD and CAT activities. PPEES pretreatment also significantly attenuated Mn-induced mitochondrial membrane potential (ΔΨm) and apoptosis. Meanwhile, PPEES pretreatment significantly reversed the Mn-induced alteration in the GRP78, GADD34, XBP-1, CHOP, Bcl-2, Bax and caspase-3 activities. Furthermore, administration of PPEES (100 and 200 mg/kg) to Mn exposed rats showed improvement of histopathological alteration in comparison to Mn-treated rats. Moreover, administration of PPEES to Mn exposed rats showed significant reduction of 8-OHdG and Bax immunoreactivity. The results suggest that PPEES treatment reduces Mn-induced oxidative stress and neuronal cell loss in SKNMC cells and in the rat brain. Therefore, PPEES may be considered as potential treat-ment in Mn-intoxicated patients. PMID:28146110

  16. Endotoxin treatment protects rats against ozone-induced lung edema: with evidence for the role of manganese superoxide dismutase

    SciTech Connect

    Rahman, I.; Massaro, D. )

    1992-03-01

    Ozone is a strong oxidizing agent that can cause lung damage and edema. There is evidence that it does so by causing peroxidation of membrane lipids. However, the elevation in lung activity of copper, zinc superoxide dismutase (Cu, ZnSOD), and manganese superoxide dismutase (MnSOD) during exposure to ozone suggests that increased production of superoxide could contribute to lung edema caused by ozone. This latter observation, and preliminary evidence that treatment of rats with endotoxin elevates lung activity of MnSOD without elevation of the activity of Cu, ZnSOD, catalase (CAT), or glutathione peroxidase (GP), led to the present study. We treated rats with endotoxin, exposed them to different concentrations of ozone, measured lung wet weight to dry weight ratio, thiobarbituric acid-reactive material (TBAR), and assayed lung tissue for Cu, ZnSOD, MnSOD, CAT, and GP activity. Our major findings are, (1) a strongly edemogenic concentration of ozone-lowered MnSOD activity; (2) endotoxin treatment of air-breathing rats did not decrease lipid peroxidation as indicated by the lung concentration of TBAR; (3) induction of increased MnSOD activity in lung by treatment with endotoxin was associated with virtually complete protection against an otherwise edemogenic concentration of ozone, with less lipid peroxidation, and with less loss of weight; and (4) this protection occurred without elevated Cu, ZnSOD, CAT, or GP activity.

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

    SciTech Connect

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

    1991-08-01

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

  18. X-ray crystal structures of manganese(II)-reconstituted and native toluene/o-xylene monooxygenase hydroxylase reveal rotamer shifts in conserved residues and an enhanced view of the protein interior.

    PubMed

    McCormick, Michael S; Sazinsky, Matthew H; Condon, Karen L; Lippard, Stephen J

    2006-11-29

    We report the X-ray crystal structures of native and manganese(II)-reconstituted toluene/o-xylene monooxygenase hydroxylase (ToMOH) from Pseudomonas stutzeri OX1 to 1.85 and 2.20 A resolution, respectively. The structures reveal that reduction of the dimetallic active site is accompanied by a carboxylate shift and alteration of the coordination environment for dioxygen binding and activation. A rotamer shift in a strategically placed asparagine 202 accompanies dimetallic center reduction and is proposed to influence protein component interactions. This rotamer shift is conserved between ToMOH and the corresponding residue in methane monooxygenase hydroxylase (MMOH). Previously unidentified hydrophobic pockets similar to those present in MMOH are assigned.

  19. Resonance Raman spectra of iron(III)-, copper(II)-, cobalt(III)-, and manganese(III)-transferrins and of bis(2,4,6-trichlorophenolato)diimidazolecopper(II) monohydrate, a possible model for copper(II) binding to transferrins.

    PubMed

    Tomimatsu, Y; Kint, S; Scherer, J R

    1976-11-02

    Fe(III), Cu(II), Co(III), and Mn(III) complexes of ovo- and human serum transferrins show resonance enhanced Raman bands near 1600, 1500, 1270, and 1170 cm-1 upon excitation with laser frequencies which fall within the visible absorption bands of those metalloproteins. Comparison of the visible absorption and resonance Raman spectra of the Cu(II)-transferrin complexes with those for the Cu(II) model compound, bis(2,4,6-trichlorophenolato)diimidazolecopper(II) monohydrate, indicates that the resonance Raman bands are due to enhancement of phenolic vibrational modes. For the model (Cu(II) compound, a normal coordinate analysis was used to aid our assignment of the observed resonance bands at 1562, 1463, 1311, and 1122 cm-1 to A1 vibrational modes of the 2,4,6-trichlorophenolato moiety. These assignments are consistent with those made for Cu(II)-transferrins. The latter assignments were based upon calculated A1 frequencies for p-methylphenol (Cummings, D.L., and Wood, J.L. (1974), J. Mol. Struct. 20, 1). The wavelength shifts in the resonance bands for the model compound from those for Cu(II)-transferrins are due to the influence of the chloro substituents on the planar vibrations of phenol. These results clearly identify tyrosine as a ligand in copper binding to transferrins.

  20. Transcriptional up-regulation of antioxidant genes by PPAR{delta} inhibits angiotensin II-induced premature senescence in vascular smooth muscle cells

    SciTech Connect

    Kim, Hyo Jung; Ham, Sun Ah; Paek, Kyung Shin; Hwang, Jung Seok; Jung, Si Young; Kim, Min Young; Jin, Hanna; Kang, Eun Sil; Woo, Im Sun; Kim, Hye Jung; Lee, Jae Heun; Chang, Ki Churl; Han, Chang Woo; Seo, Han Geuk

    2011-03-25

    Research highlights: {yields} Activation of PPAR{delta} by GW501516 significantly inhibited Ang II-induced premature senescence in hVSMCs. {yields} Agonist-activated PPAR{delta} suppressed generation of Ang II-triggered ROS with a concomitant reduction in DNA damage. {yields} GW501516 up-regulated expression of antioxidant genes, such as GPx1, Trx1, Mn-SOD and HO-1. {yields} Knock-down of these antioxidant genes abolished the effects of GW501516 on ROS production and premature senescence. -- Abstract: This study evaluated peroxisome proliferator-activated receptor (PPAR) {delta} as a potential target for therapeutic intervention in Ang II-induced senescence in human vascular smooth muscle cells (hVSMCs). Activation of PPAR{delta} by GW501516, a specific agonist of PPAR{delta}, significantly inhibited the Ang II-induced premature senescence of hVSMCs. Agonist-activated PPAR{delta} suppressed the generation of Ang II-triggered reactive oxygen species (ROS) with a concomitant reduction in DNA damage. Notably, GW501516 up-regulated the expression of antioxidant genes, such as glutathione peroxidase 1, thioredoxin 1, manganese superoxide dismutase and heme oxygenase 1. siRNA-mediated down-regulation of these antioxidant genes almost completely abolished the effects of GW501516 on ROS production and premature senescence in hVSMCs treated with Ang II. Taken together, the enhanced transcription of antioxidant genes is responsible for the PPAR{delta}-mediated inhibition of premature senescence through sequestration of ROS in hVSMCs treated with Ang II.

  1. Manganese-enhanced magnetic resonance microscopy of mineralization

    USGS Publications Warehouse

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

    2007-01-01

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

  2. Ruthenium(II) Complexes as Potential Apoptosis Inducers in Chemotherapy.

    PubMed

    Zheng, Kangdi; Wu, Qiong; Wang, Chengxi; Tan, Weijun; Mei, Wenjie

    2017-01-01

    Herein, the development of ruthenium complexes as potential apoptosis inducers, as well as their underlying mechanism has been reviewed. In recent years, various ruthenium complexes have been designed and their in vitro and in vivo inhibitory activities against various types of tumor cells have been evaluated extensively. It's demonstrated that ruthenium complexes can induce apoptosis of tumor cells through the signal pathway of mitochondria-mediated, death receptor-mediated, and/or endoplasmic reticulum (ER) stress pathways. Alternately, the binding behavior of these ruthenium(II) complexes with DNA, especially with Gquadruplex DNA may play a key role in the DNA damage of tumor cells, and thus provides a versatile tool to rational design novel ruthenium complexes with high activity and selectivity.

  3. Developmental exposure to manganese chloride induces sustained aberration of neurogenesis in the hippocampal dentate gyrus of mice.

    PubMed

    Wang, Liyun; Ohishi, Takumi; Shiraki, Ayako; Morita, Reiko; Akane, Hirotoshi; Ikarashi, Yoshiaki; Mitsumori, Kunitoshi; Shibutani, Makoto

    2012-06-01

    The effect of exogenously administered manganese (Mn) on developmental neurogenesis in the hippocampal dentate gyrus was examined in male mice after maternal exposure to MnCl(2) (0, 32, 160, or 800 ppm as Mn in diet) from gestational day 10 to day 21 after delivery on weaning. Immunohistochemistry was performed to monitor neurogenesis and interneuron subpopulations on postnatal days (PNDs) 21 and 77 (adult stage). Reelin-synthesizing γ-aminobutyric acid (GABA)ergic interneurons increased in the hilus with ≥ 160 ppm on weaning to sustain to PND 77 at 800 ppm. Apoptosis in the neuroblast-producing subgranular zone increased with 800 ppm and TUC4-expressing immature granule cells decreased with 800 ppm on weaning, whereas at the adult stage, immature granule cells increased. On PND 21, transcript levels increased with Reln and its receptor gene Lrp8 and decreased with Dpysl3 coding TUC4 in the dentate gyrus, confirming immunohistochemical results. Double immunohistochemistry revealed a sustained increase of reelin-expressing and NeuN-lacking or weakly positive immature interneurons and NeuN-expressing mature neurons in the hilus through to the adult stage as examined at 800 ppm. Brain Mn concentrations increased at both PNDs 21 and 77 in all MnCl(2)-exposed groups. These results suggest that Mn targets immature granule cells causing apoptosis and neuronal mismigration. Sustained increases in immature reelin-synthesizing GABAergic interneurons may represent continued aberration in neurogenesis and following migration to cause an excessive response for overproduction of immature granule cells through to the adult stage. Sustained high concentration of Mn in the brain may be responsible for these changes.

  4. Manganese Uptake and Distribution in the Brain after Methyl Bromide-Induced Lesions in the Olfactory Epithelia

    PubMed Central

    Thompson, Khristy J.; Molina, Ramon M.; Donaghey, Thomas; Savaliya, Sandeep; Schwob, James E.; Brain, Joseph D.

    2011-01-01

    Manganese (Mn) is an essential nutrient with potential neurotoxic effects. Mn deposited in the nose is apparently transported to the brain through anterograde axonal transport, bypassing the blood-brain barrier. However, the role of the olfactory epithelial cells in Mn transport from the nasal cavity to the blood and brain is not well understood. We utilized the methyl bromide (MeBr) lesion model wherein the olfactory epithelium fully regenerates in a time-dependent and cell type–specific manner over the course of 6–8 weeks postinjury. We instilled 54MnCl2 intranasally at different recovery periods to study the role of specific olfactory epithelial cell types in Mn transport. 54MnCl2 was instilled at 2, 4, 7, 21, and 56 days post-MeBr treatment. 54Mn concentrations in the blood were measured over the first 4-h period and in the brain and other tissues at 7 days postinstillation. Age-matched control rats were similarly studied at 2 and 56 days. Blood and tissue 54Mn levels were reduced initially but returned to control values by day 7 post-MeBr exposure, coinciding with the reestablishment of sustentacular cells. Brain 54Mn levels also decreased but returned to control levels only by 21 days, the period near the completion of neuronal regeneration/bulbar reinnervation. Our data show that Mn transport to the blood and brain temporally correlated with olfactory epithelial regeneration post-MeBr injury. We conclude that (1) sustentacular cells are necessary for Mn transport to the blood and (2) intact axonal projections are required for Mn transport from the nasal cavity to the olfactory bulb and brain. PMID:21177252

  5. Manganese uptake and distribution in the brain after methyl bromide-induced lesions in the olfactory epithelia.

    PubMed

    Thompson, Khristy J; Molina, Ramon M; Donaghey, Thomas; Savaliya, Sandeep; Schwob, James E; Brain, Joseph D

    2011-03-01

    Manganese (Mn) is an essential nutrient with potential neurotoxic effects. Mn deposited in the nose is apparently transported to the brain through anterograde axonal transport, bypassing the blood-brain barrier. However, the role of the olfactory epithelial cells in Mn transport from the nasal cavity to the blood and brain is not well understood. We utilized the methyl bromide (MeBr) lesion model wherein the olfactory epithelium fully regenerates in a time-dependent and cell type-specific manner over the course of 6-8 weeks postinjury. We instilled (54)MnCl(2) intranasally at different recovery periods to study the role of specific olfactory epithelial cell types in Mn transport. (54)MnCl(2) was instilled at 2, 4, 7, 21, and 56 days post-MeBr treatment. (54)Mn concentrations in the blood were measured over the first 4-h period and in the brain and other tissues at 7 days postinstillation. Age-matched control rats were similarly studied at 2 and 56 days. Blood and tissue (54)Mn levels were reduced initially but returned to control values by day 7 post-MeBr exposure, coinciding with the reestablishment of sustentacular cells. Brain (54)Mn levels also decreased but returned to control levels only by 21 days, the period near the completion of neuronal regeneration/bulbar reinnervation. Our data show that Mn transport to the blood and brain temporally correlated with olfactory epithelial regeneration post-MeBr injury. We conclude that (1) sustentacular cells are necessary for Mn transport to the blood and (2) intact axonal projections are required for Mn transport from the nasal cavity to the olfactory bulb and brain.

  6. [Heparin-induced thrombocytopenia type II: reexposure to heparin].

    PubMed

    Matthies, B; Bürger, T; Koch, B; Böck, M

    1999-10-29

    At the age of 55 years a now 70-year-old man had his aortic valve replaced by a prosthetic (Björk-Shiley) valve, and 11 years later a VDD pacemaker had been implanted. 18 months before the latest admission he had been hospitalized for treatment of staphylococcal endocarditis involving the aortic prothesis. At that time thrombocytopenia developed during heparin administration, diagnosed clinically and with the heparin-induced platelet activity (HIPA) test as type II heparin induced thrombocytopenia. His latest admission was for the diagnosis and treatment of peripheral arterial disease of the right leg (Fontaine stage IIb). Right popliteal and pedal pulses were not palpable. He was able to walk pain-free for only 70 m. Doppler sonography demonstrated an arm-leg index on the right of 0.7. Angiography revealed marked stenosis in the right superficial femoral artery and a filiform stenosis in the right popliteal artery. Both stenoses were relieved by percutaneous transluminal balloon angioplasty, in the course of which 5000 IU heparin were administered as a bolus intraarterially. Postoperative anticoagulation was maintained for 2 days with recombinant hirudin. There was no evidence of platelet reduction or heparin-induced antibodies despite the renewed infusion of heparin. Single re-administration of heparin in a patient who had developed a type II heparin-induced thrombocytopenia several years before does not necessarily lead to a booster of antibodies and thus to a reduction of platelets in the peripheral blood. It is a moot point whether the course in this case was an exception or the rule.

  7. Non-heme manganese catalase--the 'other' catalase.

    PubMed

    Whittaker, James W

    2012-09-15

    Non-heme manganese catalases are widely distributed over microbial life and represent an environmentally important alternative to heme-containing catalases in antioxidant defense. Manganese catalases contain a binuclear manganese complex as their catalytic active site rather than a heme, and cycle between Mn(2)(II,II) and Mn(2)(III,III) states during turnover. X-ray crystallography has revealed the key structural elements of the binuclear manganese active site complex that can serve as the starting point for computational studies on the protein. Four manganese catalase enzymes have been isolated and characterized, and the enzyme appears to have a broad phylogenetic distribution including both bacteria and archae. More than 100 manganese catalase genes have been annotated in genomic databases, although the assignment of many of these putative manganese catalases needs to be experimentally verified. Iron limitation, exposure to low levels of peroxide stress, thermostability and cyanide resistance may provide the biological and environmental context for the occurrence of manganese catalases. Copyright © 2011 Elsevier Inc. All rights reserved.

  8. Kr II laser-induced fluorescence for measuring plasma acceleration.

    PubMed

    Hargus, W A; Azarnia, G M; Nakles, M R

    2012-10-01

    We present the application of laser-induced fluorescence of singly ionized krypton as a diagnostic technique for quantifying the electrostatic acceleration within the discharge of a laboratory cross-field plasma accelerator also known as a Hall effect thruster, which has heritage as spacecraft propulsion. The 728.98 nm Kr II transition from the metastable 5d(4)D(7/2) to the 5p(4)P(5/2)(∘) state was used for the measurement of laser-induced fluorescence within the plasma discharge. From these measurements, it is possible to measure velocity as krypton ions are accelerated from near rest to approximately 21 km/s (190 eV). Ion temperature and the ion velocity distributions may also be extracted from the fluorescence data since available hyperfine splitting data allow for the Kr II 5d(4)D(7/2)-5p(4)P(5/2)(∘) transition lineshape to be modeled. From the analysis, the fluorescence lineshape appears to be a reasonable estimate for the relatively broad ion velocity distributions. However, due to an apparent overlap of the ion creation and acceleration regions within the discharge, the distributed velocity distributions increase ion temperature determination uncertainty significantly. Using the most probable ion velocity as a representative, or characteristic, measure of the ion acceleration, overall propellant energy deposition, and effective electric fields may be calculated. With this diagnostic technique, it is possible to nonintrusively characterize the ion acceleration both within the discharge and in the plume.

  9. Kr II laser-induced fluorescence for measuring plasma acceleration

    NASA Astrophysics Data System (ADS)

    Hargus, W. A.; Azarnia, G. M.; Nakles, M. R.

    2012-10-01

    We present the application of laser-induced fluorescence of singly ionized krypton as a diagnostic technique for quantifying the electrostatic acceleration within the discharge of a laboratory cross-field plasma accelerator also known as a Hall effect thruster, which has heritage as spacecraft propulsion. The 728.98 nm Kr II transition from the metastable 5d4D7/2 to the 5p ^4P^circ _{5/2} state was used for the measurement of laser-induced fluorescence within the plasma discharge. From these measurements, it is possible to measure velocity as krypton ions are accelerated from near rest to approximately 21 km/s (190 eV). Ion temperature and the ion velocity distributions may also be extracted from the fluorescence data since available hyperfine splitting data allow for the Kr II 5d4D7/2-5p ^4P^circ _{5/2} transition lineshape to be modeled. From the analysis, the fluorescence lineshape appears to be a reasonable estimate for the relatively broad ion velocity distributions. However, due to an apparent overlap of the ion creation and acceleration regions within the discharge, the distributed velocity distributions increase ion temperature determination uncertainty significantly. Using the most probable ion velocity as a representative, or characteristic, measure of the ion acceleration, overall propellant energy deposition, and effective electric fields may be calculated. With this diagnostic technique, it is possible to nonintrusively characterize the ion acceleration both within the discharge and in the plume.

  10. Solubilisation effect of spent wash on oxide-ores of manganese and iron.

    PubMed

    Pervez, S; Pandey, G S

    1991-09-01

    Samples of iron ore (haematite) and manganese ore (pyrolusite) of known compositions were equilibrated with aliquots of analysed sample of spent wash. The concentrations of iron(II), iron(III), complexed iron, manganese(II) ions and complexed Mn-ions were determined after increasing durations. One litre of the spent wash was found to extract out 141 mg of total iron and 161 mg of total manganese. In case of iron, the predominance was of iron(II) (92%), whereas in case of manganese it was of the complexed form (95%).

  11. Anthocyanin-rich açaí (Euterpe oleracea Mart.) extract attenuates manganese-induced oxidative stress in rat primary astrocyte cultures.

    PubMed

    da Silva Santos, Vivian; Bisen-Hersh, Emily; Yu, Yingchun; Cabral, Ingridy Simone Ribeiro; Nardini, Viviani; Culbreth, Megan; Teixeira da Rocha, João Batista; Barbosa, Fernando; Aschner, Michael

    2014-01-01

    Manganese (Mn) is an essential element for human health. However, at high concentrations Mn may be neurotoxic. Mn accumulates in astrocytes, affecting their redox status. In view of the high antioxidant and anti-inflammatory properties of the exotic Brazilian fruit açaí (Euterpe oleracea Mart.), its methanolic extract was obtained by solid-phase extraction (SPE). This açaí extract showed considerable anthocyanins content and direct antioxidant capacity. The açaí extract scavenged 2,2-diphenyl-1-picrylhydrazyl radicals (DPPH•) with an EC₅₀ of 19.1 ppm, showing higher antioxidant activity compared to butylated hydroxytoluene (BHT), but lower than ascorbic acid and quercetin. This obtained açaí extract also attenuated Mn-induced oxidative stress in primary cultured astrocytes. Specifically, the açaí extract at an optimal and nutritionally relevant concentration of 0.1 μg/ml prevented Mn-induced oxidative stress by (1) restoring GSH/GSSG ratio and net glutamate uptake, (2) protecting astrocytic membranes from lipid peroxidation, and (3) decreasing Mn-induced expression of erythroid 2-related factor (Nrf2) protein. A larger quantity of açaí extract exacerbated the effects of Mn on these parameters except with respect to lipid peroxidation assessed by means of F₂-isoprostanes. These studies indicate that at nutritionally relevant concentration, anthocyanins obtained from açaí protect astrocytes against Mn neurotoxicity, but at high concentrations, the "pro-oxidant" effects of its constituents likely prevail. Future studies may be profitably directed at potential protective effects of açaí anthocyanins in nutraceutical formulations.

  12. Changes in rat urinary porphyrin profiles predict the magnitude of the neurotoxic effects induced by a mixture of lead, arsenic and manganese.

    PubMed

    Andrade, Vanda; Mateus, M Luísa; Batoréu, M Camila; Aschner, Michael; Marreilha dos Santos, A P

    2014-12-01

    The neurotoxic metals lead (Pb), arsenic (As) and manganese (Mn) are ubiquitous contaminants occurring as mixtures in environmental settings. The three metals may interfere with enzymes of the heme bioshyntetic pathway, leading to excessive porphyrin accumulation, which per se may trigger neurotoxicity. Given the multi-mechanisms associated with metal toxicity, we posited that a single biomarker is unlikely to predict neurotoxicity that is induced by a mixture of metals. Our objective was to evaluate the ability of a combination of urinary porphyrins to predict the magnitude of motor activity impairment induced by a mixture of Pb/As/Mn. Five groups of Wistar rats were treated for 8 days with Pb (5mg/kg), As (60 mg/L) or Mn (10mg/kg), and the 3-metal mixture (same doses as the single metals) along with a control group. Motor activity was evaluated after the administration of the last dose and 24-hour (h) urine was also collected after the treatments. Porphyrin profiles were determined both in the urine and brain. Rats treated with the metal-mixture showed a significant decrease in motor parameters compared with controls and the single metal-treated groups. Both brain and urinary porphyrin levels, when combined and analyzed by multiple linear regressions, were predictable of motor activity (p<0.05). The magnitude of change in urinary porphyrin profiles was consistent with the greatest impairments in motor activity as determined by receiver operating characteristic (ROC) curves, with a sensitivity of 88% and a specificity of 96%. Our work strongly suggests that the use of a linear combination of urinary prophyrin levels accurately predicts the magnitude of motor impairments in rats that is induced by a mixture of Pb, As and Mn. Copyright © 2014. Published by Elsevier B.V.

  13. Quercetin Attenuates Manganese-Induced Neuroinflammation by Alleviating Oxidative Stress through Regulation of Apoptosis, iNOS/NF-κB and HO-1/Nrf2 Pathways.

    PubMed

    Bahar, Entaz; Kim, Ji-Ye; Yoon, Hyonok

    2017-09-15

    Manganese (Mn) is an essential trace element required for the development of human body and acts as an enzyme co-factor or activator for various reactions of metabolism. While essential in trace amounts, excessive Mn exposure can result in toxic accumulations in human brain tissue and resulting extrapyramidal symptoms called manganism similar to idiopathic Parkinson's disease (PD). Quercetin (QCT) has been demonstrated to play an important role in altering the progression of neurodegenerative diseases by protecting against oxidative stress. This study aimed to investigate the protective effect of QCT on Mn-induced neurotoxicity and the underlying mechanism in SK-N-MC human neuroblastoma cell line and Sprague-Dawley (SD) male rat brain. The results showed that Mn treatment significantly decreased the cell viability of SK-N-MC cell and increased the release of lactate dehydrogenase (LDH), which was attenuated by QCT pretreatment at 10 and 20 µg/mL. Compared to the Mn alone group, QCT pretreatment significantly attenuated Mn-induced oxidative stress, mitochondrial dysfunction and apoptosis. Meanwhile, QCT pretreatment markedly downregulated the NF-κB but upregulated the heme oxygenase-1 (HO-1) and Nrf2 proteins, compared to the Mn alone group. Our result showed the beneficial effect of QCT on hematological parameters against Mn in rat brain. QCT decrease reactive oxygen species (ROS) and protein carbonyl levels and increased Cu/Zn-superoxide dismutase (SOD) activity induced in Mn-treated rats. QCT administration caused a significant reduction in the Mn-induced neuroinflammation by inhibiting the expression of inflammatory markers such as tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6) cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS). QCT lowered the Mn elevated levels of various downstream apoptotic markers, including Bax, cytochrome c, cleaved caspase-3 and polymerase-1 (PARP-1), while QCT treatment upregulated

  14. Spatial memory training induces morphological changes detected by manganese-enhanced MRI in the hippocampal CA3 mossy fiber terminal zone.

    PubMed

    Zhang, Binbin; Chuang, Kai-Hsiang; Tjio, Ci'en; Chen, Way Cherng; Sheu, Fwu-Shan; Routtenberg, Aryeh

    2016-03-01

    Hippocampal mossy fibers (MFs) can show plasticity of their axon terminal arbor consequent to learning a spatial memory task. Such plasticity is seen as translaminar sprouting from the stratum lucidum (SL) of CA3 into the stratum pyramidale (SP) and the stratum oriens (SO). However, the functional role of this presynaptic remodeling is still obscure. In vivo imaging that allows longitudinal observation of such remodeling could provide a deeper understanding of this presynaptic growth phenomenon as it occurs over time. Here we used manganese-enhanced magnetic resonance imaging (MEMRI), which shows a high-contrast area that co-localizes with the MFs. This technique was applied in the detection of learning-induced MF plasticity in two strains of rats. Quantitative analysis of a series of sections in the rostral dorsal hippocampus showed increases in the CA3a' area in MEMRI of trained Wistar rats consistent with the increased SO+SP area seen in the Timm's staining. MF plasticity was not seen in the trained Lister-Hooded rats in either MEMRI or in Timm's staining. This indicates the potential of MEMRI for revealing neuro-architectures and plasticity of the hippocampal MF system in vivo in longitudinal studies.

  15. The Two-Component System ArlRS and Alterations in Metabolism Enable Staphylococcus aureus to Resist Calprotectin-Induced Manganese Starvation

    PubMed Central

    Radin, Jana N.; Párraga Solórzano, Paola K.; Kehl-Fie, Thomas E.

    2016-01-01

    During infection the host imposes manganese and zinc starvation on invading pathogens. Despite this, Staphylococcus aureus and other successful pathogens remain capable of causing devastating disease. However, how these invaders adapt to host-imposed metal starvation and overcome nutritional immunity remains unknown. We report that ArlRS, a global staphylococcal virulence regulator, enhances the ability of S. aureus to grow in the presence of the manganese-and zinc-binding innate immune effector calprotectin. Utilization of calprotectin variants with altered metal binding properties revealed that strains lacking ArlRS are specifically more sensitive to manganese starvation. Loss of ArlRS did not alter the expression of manganese importers or prevent S. aureus from acquiring metals. It did, however, alter staphylococcal metabolism and impair the ability of S. aureus to grow on amino acids. Further studies suggested that relative to consuming glucose, the preferred carbon source of S. aureus, utilizing amino acids reduced the cellular demand for manganese. When forced to use glucose as the sole carbon source S. aureus became more sensitive to calprotectin compared to when amino acids are provided. Infection experiments utilizing wild type and calprotectin-deficient mice, which have defects in manganese sequestration, revealed that ArlRS is important for disease when manganese availability is restricted but not when this essential nutrient is freely available. In total, these results indicate that altering cellular metabolism contributes to the ability of pathogens to resist manganese starvation and that ArlRS enables S. aureus to overcome nutritional immunity by facilitating this adaptation. PMID:27902777

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

    SciTech Connect

    Zheng, Gang; Chen, Jingyuan; Zheng, Wei

    2012-05-01

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

  17. Manganese-Induced Atypical Parkinsonism Is Associated with Altered Basal Ganglia Activity and Changes in Tissue Levels of Monoamines in the Rat

    PubMed Central

    Bouabid, Safa; Delaville, Claire; De Deurwaerdère, Philippe; Lakhdar-Ghazal, Nouria; Benazzouz, Abdelhamid

    2014-01-01

    Manganese neurotoxicity is associated with motor and cognitive disturbances known as Manganism. However, the mechanisms underlying these deficits remain unknown. Here we investigated the effects of manganese intoxication on motor and non-motor parkinsonian-like deficits such as locomotor activity, motor coordination, anxiety and “depressive-like” behaviors. Then, we studied the impact of this intoxication on the neuronal activity, the globus pallidus (GP) and subthalamic nucleus (STN). At the end of experiments, post-mortem tissue level of the three monoamines (dopamine, norepinephrine and serotonin) has been determined. The experiments were carried out in adult Sprague-Dawley rats, daily treated with MnCl2 (10 mg/kg/, i.p.) for 5 weeks. We show that manganese progressively reduced locomotor activity as well as motor coordination in parallel with the manifestation of anxiety and “depressive-like” behaviors. Electrophysiological results show that, while majority of GP and STN neurons discharged regularly in controls, manganese increased the number of GP and STN neurons discharging irregularly and/or with bursts. Biochemical results show that manganese significantly decreased tissue levels of norepinephrine and serotonin with increased metabolism of dopamine in the striatum. Our data provide evidence that manganese intoxication is associated with impaired neurotransmission of monoaminergic systems, which is at the origin of changes in basal ganglia neuronal activity and the manifestation of motor and non-motor deficits similar to those observed in atypical Parkinsonism. PMID:24896650

  18. Kr II laser-induced fluorescence for measuring plasma acceleration

    SciTech Connect

    Hargus, W. A. Jr.

    2012-10-15

    We present the application of laser-induced fluorescence of singly ionized krypton as a diagnostic technique for quantifying the electrostatic acceleration within the discharge of a laboratory cross-field plasma accelerator also known as a Hall effect thruster, which has heritage as spacecraft propulsion. The 728.98 nm Kr II transition from the metastable 5d{sup 4}D{sub 7/2} to the 5p{sup 4}P{sub 5/2}{sup Ring-Operator} state was used for the measurement of laser-induced fluorescence within the plasma discharge. From these measurements, it is possible to measure velocity as krypton ions are accelerated from near rest to approximately 21 km/s (190 eV). Ion temperature and the ion velocity distributions may also be extracted from the fluorescence data since available hyperfine splitting data allow for the Kr II 5d{sup 4}D{sub 7/2}-5p{sup 4}P{sub 5/2}{sup Ring-Operator} transition lineshape to be modeled. From the analysis, the fluorescence lineshape appears to be a reasonable estimate for the relatively broad ion velocity distributions. However, due to an apparent overlap of the ion creation and acceleration regions within the discharge, the distributed velocity distributions increase ion temperature determination uncertainty significantly. Using the most probable ion velocity as a representative, or characteristic, measure of the ion acceleration, overall propellant energy deposition, and effective electric fields may be calculated. With this diagnostic technique, it is possible to nonintrusively characterize the ion acceleration both within the discharge and in the plume.

  19. Nitric oxide inhibits topoisomerase II activity and induces resistance to topoisomerase II-poisons in human tumor cells.

    PubMed

    Kumar, Ashutosh; Ehrenshaft, Marilyn; Tokar, Erik J; Mason, Ronald P; Sinha, Birandra K

    2016-07-01

    Etoposide and doxorubicin, topoisomerase II poisons, are important drugs for the treatment of tumors in the clinic. Topoisomerases contain several free sulfhydryl groups which are important for their activity and are also potential targets for nitric oxide (NO)-induced nitrosation. NO, a physiological signaling molecule nitrosates many cellular proteins, causing altered protein and cellular functions. Here, we have evaluated the roles of NO/NO-derived species in the activity/stability of topo II both in vitro and in human tumor cells, and in the cytotoxicity of topo II-poisons, etoposide and doxorubicin. Treatment of purified topo IIα with propylamine propylamine nonoate (PPNO), an NO donor, resulted in inhibition of both the catalytic and relaxation activity in vitro, and decreased etoposide-dependent cleavable complex formation in both human HT-29 colon and MCF-7 breast cancer cells. PPNO treatment also induced significant nitrosation of topo IIα protein in these human tumor cells. These events, taken together, caused a significant resistance to etoposide in both cell lines. However, PPNO had no effect on doxorubicin-induced cleavable complex formation, or doxorubicin cytotoxicity in these cell lines. Inhibition of topo II function by NO/NO-derived species induces significant resistance to etoposide, without affecting doxorubicin cytotoxicity in human tumor cells. As tumors express inducible nitric oxide synthase and generate significant amounts of NO, modulation of topo II functions by NO/NO-derived species could render tumors resistant to certain topo II-poisons in the clinic. Published by Elsevier B.V.

  20. Photoproduction of catalase-insensitive peroxides on the donor side of manganese-depleted photosystem II: evidence with a specific fluorescent probe.

    PubMed

    Khorobrykh, Sergey A; Khorobrykh, Andrei A; Yanykin, Denis V; Ivanov, Boris N; Klimov, Vyacheslav V; Mano, Jun'ichi

    2011-12-13

    The photoproduction of organic peroxides (ROOH) in photosystem II (PSII) membranes was studied using the fluorescent probe Spy-HP. Two types of peroxide, highly lipophilic ones and relatively hydrophilic ones, were distinguished by the rate of reaction with Spy-HP; the former oxidized Spy-HP to the higher fluorescent form Spy-HPOx within 5 min, while the latter did so very slowly (the reaction was still not completed after 180 min). The level of photoproduction of these peroxides was significantly larger in the alkaline-treated, Mn-depleted PSII membranes than that in the untreated membranes, and it was suppressed by an artificial electron donor (diphenylcarbazide or ferrocyanide) and by the electron transport inhibitor diuron. Postillumination addition of Fe(2+) ions, which degrade peroxides by the Fenton mechanism, abolished the accumulation of Spy-HPOx, but catalase did not change the peroxide level, indicating that the detected species were organic peroxides, excluding H(2)O(2). These results agreed with our previous observation of an electron transport-dependent O(2) consumption on the PSII donor side and indicated that ROOH accumulated via a radical chain reaction that started with the formation of organic radicals on the donor side. Illumination (λ > 600 nm; 1500 μmol of photons m(-2) s(-1)) of the Mn-depleted PSII membranes for 3 min resulted in the formation of nearly 200 molecules of hydrophilic ROOH per reaction center, but only four molecules of highly lipophilic ROOH. The limited formation of the latter was due to the limited supply of its precursor to the reaction, suggesting that it represented structurally fixed peroxides, i.e., either protein peroxides or peroxides of the lipids tightly bound to the core complex. These ROOH forms, likely including several species derived from lipid peroxides, may mediate the donor side-induced photoinhibition of PSII via protein modification.

  1. Comparison of photosynthesis recovery dynamics in floating leaves of Trapa natans after inhibition by manganese or molybdenum: effects on Photosystem II.

    PubMed

    Baldisserotto, Costanza; Ferroni, Lorenzo; Pantaleoni, Laura; Pancaldi, Simonetta

    2013-09-01

    The aquatic plant Trapa natans L. is highly resistant to Mn and moderately resistant to Mo, mainly thanks to its ability to sequestrate the metals by chelation in the vacuole. Excess of Mn and Mo causes somewhat aspecific toxicity symptoms in plants, but the main target of their toxicity seems to be the photosynthetic process. In this work, we aimed at understanding how the effect on photosynthesis caused by Mn (130 μM, full recovery) or Mo (50 μM, partial recovery) in T. natans is linked to changes occurring in the photosynthetic apparatus, with emphasis on Photosystem II (PSII), during a 10 day treatment with these metals. The time-course of net photosynthesis, photosynthetic pigment content, amount of PSII and its peripheral antenna LHCII, and room-temperature fluorescence emission ratios F694/F680 and F700/(F685 + F695) showed that the early inhibiting effect of Mo and Mn (one day exposure) was essentially non-specific with respect to the metal, though more marked in Mo- than in Mn-treated plants. During the subsequent recovery phase, Mo still impaired PSII assembly and, consequently, photosynthesis could not reach the control values. Conversely, in Mn-treated plants the amount of PSII was fully re-established, as was photosynthesis, but the metal induced the accumulation of LHCII. The extent of inhibition and the effectiveness of photosynthesis recovery are proposed to reflect the different ability of T. natans to sequestrate safely excess Mn or Mo in vacuoles.

  2. Isostructural dinuclear phenoxo-/acetato-bridged manganese(II), cobalt(II), and zinc(II) complexes with labile sites: kinetics of transesterification of 2-hydroxypropyl-p-nitrophenylphosphate.

    PubMed

    Arora, Himanshu; Barman, Suman K; Lloret, Francesc; Mukherjee, Rabindranath

    2012-05-21

    Using the dinucleating phenol-based ligand 2,6-bis[3-(pyridin-2-yl)pyrazol-1-ylmethyl]-4-methylphenol] (HL(2)), in its deprotonated form, the six new dinuclear complexes [M(II)(2)(L(2))(μ-O(2)CMe)(2)(MeCN)(2)][PF(6)] (M = Mn (2a), Co (3a), Zn (4a)) and [M(II)(2)(L(2))(μ-O(2)CMe)(2)(MeCN)(2)][BPh(4)] (M = Mn (2b), Co (3b), Zn (4b)) have been synthesized. Crystallographic analyses on 2b·2MeCN, 3b·2MeCN, and 4b·2MeCN reveal that these complexes have closely similar μ-phenoxo bis(μ-carboxylato) structures. The physicochemical properties (absorption and ESI-MS spectral data, 2a,b, 3a,b, and 4a,b; (1)H NMR, 4a,b) of the cations of 2a-4a are identical with those of 2b-4b. Each metal ion is terminally coordinated by a pyrazole nitrogen and a pyridyl nitrogen from a 3-(pyridin-2-yl)pyrazole unit and a solvent molecule (MeCN). Thus, each metal center assumes distorted-octahedral M(II)N(3)O(3) coordination. Temperature-dependent magnetic studies on Mn(II) and Co(II) dimers reveal the presence of intramolecular antiferromagnetic (J = -8.5 cm(-1)) for 2b and ferromagnetic exchange coupling (J = +2.51 cm(-1)) for 3b, on the basis of the Hamiltonian H = -JS(1)·S(2). The exchange mechanism is discussed on the basis of magneto-structural parameters (M···M distance). Spectroscopic properties of the complexes have also been investigated. The pH titration and kinetics of phosphatase (transesterification) activity on 2-hydroxypropyl-p-nirophenylphosphate (HPNP) were studied in MeOH/H(2)O (33%, v/v) with 2a-4a, due to solubility reasons. This comparative kinetic study revealed the effect of the metal ion on the rate of hydrolysis of HPNP, which has been compared with what we recently reported for [Ni(II)(2)(L(2))(μ-O(2)CMe)(2)(MeOH)(H(2)O)][ClO(4)] (1a). The efficacy in the order of conversion of substrate to product (p-nitrophenolate ion) follows the order 4a > 3a > 2a > 1a, under identical experimental conditions. Notably, this trend follows the decrease of pK(a) values of

  3. Sorption behavior of the Pt(II) complex anion on manganese dioxide (δ-MnO2): a model reaction to elucidate the mechanism by which Pt is concentrated into a marine ferromanganese crust

    NASA Astrophysics Data System (ADS)

    Maeno, Mamiko Yamashita; Ohashi, Hironori; Yonezu, Kotaro; Miyazaki, Akane; Okaue, Yoshihiro; Watanabe, Koichiro; Ishida, Tamao; Tokunaga, Makoto; Yokoyama, Takushi

    2016-02-01

    It is difficult to directly investigate the chemical state of Pt in marine ferromanganese crusts (a mixture of hydrous iron(III) oxide and manganese dioxide (δ-MnO2)) because it is present at extremely low concentration levels. This paper attempts to elucidate the mechanism by which Pt is concentrated into marine ferromanganese crust from the Earth's continental crust through ocean water. In this investigation, the sorption behavior of the Pt(II) complex ions on the surface of the δ-MnO2 that is a host of Pt was examined as a model reaction. The δ-MnO2 sorbing Pt was characterized by X-ray photoelectron spectroscopy (XPS) and X-ray absorption fine structure (XAFS) to determine the chemical state of the Pt. Hydrolytic Pt(II) complex ions were specifically sorbed above pH 6 by the formation of a Mn-O-Pt bond. XPS spectra and XANES spectra for δ-MnO2 sorbing Pt showed that the sorbed Pt(II) was oxidized to Pt(IV) on δ-MnO2. The extended X-ray absorption fine structure (EXAFS) analysis showed that the coordination structure of Pt sorbed on δ-MnO2 is almost the same as that of the [Pt(OH)6]2- complex ion used as a standard. Therefore, the mechanism for the concentration of Pt in marine ferromanganese crust may be an oxidative substitution (penetration of Pt(IV) into structure of δ-MnO2) by a reduction-oxidation reaction between Pt(II) in [PtCl4-n(OH)n]2- and Mn(IV) in δ-MnO2 through a Mn-O-Pt bond.

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

    PubMed

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

    2012-11-01

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

  5. Air Manganese Study

    EPA Pesticide Factsheets

    In November 2011 US EPA researchers conducted a health study of airborne manganese exposure in East Liverpool, Ohio. This Web site discusses preliminary results of the study and provides background and other related information.

  6. Peumus boldus (Boldo) Aqueous Extract Present Better Protective Effect than Boldine Against Manganese-Induced Toxicity in D. melanogaster.

    PubMed

    Bianchini, Matheus Chimelo; Gularte, Claudia Ortiz Alves; Escoto, Dandara Fidélis; Pereira, Geovana; Gayer, Mateus Cristofari; Roehrs, Rafael; Soares, Félix Alexandre Antunes; Puntel, Robson L

    2016-10-01

    The cellular, intracellular and molecular mechanism(s) underlying the toxicity of Mn are still incompletely understood, although several points concerning Mn neurotoxicity have been addressed. Importantly, oxidative changes have been reported to be involved in Mn-induced toxicity. As a consequence, antioxidants are expected to offer protection in Drosophila melanogaster exposed to this metal. So, in this study we evaluated the hypothesis that the aqueous extract of boldo (Peumus boldus), and its alkaloids boldine, could prevent/ameliorate behavioral and oxidative alterations induced by Mn in a D. melanogaster intoxication model. Adult wild-type flies were concomitantly exposed to Mn (3 mM) and boldo aqueous extract (5 mg/mL) or boldine (327.37 µg/mL) in the food during 9 days. Mn-fed flies had a worse performance in the negative geotaxis assay and in the open-field test, as well as a higher incidence of mortality and TBARS levels in head and body, when compared to control group. Boldo aqueous extract was found to reduce the mortality rate of the flies exposed to Mn. In turn, boldine was ineffective against Mn-induced mortality and significantly increases mortality per se. Additionally, Mn-induced locomotors dysfunction were fully ameliorated by boldo crude extract and only partially ameliorated by boldine. Likewise, boldo completely normalize head and body TBARS levels, whereas boldine only partially normalize in body. Finally, we found that flies treated with Mn presented significantly decrease in dopamine levels. Our results suggest that boldo crude extract can exert protective effect against Mn-induced toxicity in D. melanogaster, whereas boldine do not. Moreover, our data confirm the utility of this model to investigate potential therapeutic strategies on movement disorders, such as that caused by Mn.

  7. Production of Manganese Oxide Nanoparticles by Shewanella Species

    PubMed Central

    Farooqui, Saad M.; White, Alan R.

    2016-01-01

    ABSTRACT Several species of the bacterial genus Shewanella are well-known dissimilatory reducers of manganese under anaerobic conditions. In fact, Shewanella oneidensis is one of the most well studied of all metal-reducing bacteria. In the current study, a number of Shewanella strains were tested for manganese-oxidizing capacity under aerobic conditions. All were able to oxidize Mn(II) and to produce solid dark brown manganese oxides. Shewanella loihica strain PV-4 was the strongest oxidizer, producing oxides at a rate of 20.3 mg/liter/day and oxidizing Mn(II) concentrations of up to 9 mM. In contrast, S. oneidensis MR-1 was the weakest oxidizer tested, producing oxides at 4.4 mg/liter/day and oxidizing up to 4 mM Mn(II). Analysis of products from the strongest oxidizers, i.e., S. loihica PV-4 and Shewanella putrefaciens CN-32, revealed finely grained, nanosize, poorly crystalline oxide particles with identical Mn oxidation states of 3.86. The biogenic manganese oxide products could be subsequently reduced within 2 days by all of the Shewanella strains when culture conditions were made anoxic and an appropriate nutrient (lactate) was added. While Shewanella species were detected previously as part of manganese-oxidizing consortia in natural environments, the current study has clearly shown manganese-reducing Shewanella species bacteria that are able to oxidize manganese in aerobic cultures. IMPORTANCE Members of the genus Shewanella are well known as dissimilatory manganese-reducing bacteria. This study shows that a number of species from Shewanella are also capable of manganese oxidation under aerobic conditions. Characterization of the products of the two most efficient oxidizers, S. loihica and S. putrefaciens, revealed finely grained, nanosize oxide particles. With a change in culture conditions, the manganese oxide products could be subsequently reduced by the same bacteria. The ability of Shewanella species both to oxidize and to reduce manganese indicates

  8. Surface Mn(II) oxidation actuated by a multicopper oxidase in a soil bacterium leads to the formation of manganese oxide minerals

    PubMed Central

    Zhang, Zhen; Zhang, Zhongming; Chen, Hong; Liu, Jin; Liu, Chang; Ni, Hong; Zhao, Changsong; Ali, Muhammad; Liu, Fan; Li, Lin

    2015-01-01

    In this manuscript, we report that a bacterial multicopper oxidase (MCO266) catalyzes Mn(II) oxidation on the cell surface, resulting in the surface deposition of Mn(III) and Mn(IV) oxides and the gradual formation of bulky oxide aggregates. These aggregates serve as nucleation centers for the formation of Mn oxide micronodules and Mn-rich sediments. A soil-borne Escherichia coli with high Mn(II)-oxidizing activity formed Mn(III)/Mn(IV) oxide deposit layers and aggregates under laboratory culture conditions. We engineered MCO266 onto the cell surfaces of both an activity-negative recipient and wild-type strains. The results confirmed that MCO266 governs Mn(II) oxidation and initiates the formation of deposits and aggregates. By contrast, a cell-free substrate, heat-killed strains, and intracellularly expressed or purified MCO266 failed to catalyze Mn(II) oxidation. However, purified MCO266 exhibited Mn(II)-oxidizing activity when combined with cell outer membrane component (COMC) fractions in vitro. We demonstrated that Mn(II) oxidation and aggregate formation occurred through an oxygen-dependent biotic transformation process that requires a certain minimum Mn(II) concentration. We propose an approximate electron transfer pathway in which MCO266 transfers only one electron to convert Mn(II) to Mn(III) and then cooperates with other COMC electron transporters to transfer the other electron required to oxidize Mn(III) to Mn(IV). PMID:26039669

  9. Adsorption of antimony(V) onto Mn(II)-enriched surfaces of manganese-oxide and FeMn binary oxide.

    PubMed

    Liu, Ruiping; Xu, Wei; He, Zan; Lan, Huachun; Liu, Huijuan; Qu, Jiuhui; Prasai, Tista

    2015-11-01

    Manganese(IV) oxide [Mn(IV)] potentially oxidizes antimony(III) [Sb(III)] to antimony(V) [Sb(V)] and improves Sb removal by FeMn binary oxide (FMBO) through an oxidation-adsorption mechanism. This study focused on the effect of Mn(IV) reductive dissolution by potassium sulfite (K2SO3) on Sb(V) adsorption onto manganese oxide (Mn-oxide) and FMBO. The maximum Sb(V) adsorption (Qmax,Sb(V)) increased from 1.0 to 1.1 mmol g(-1) for FMBO and from 0.4 to 0.6 mmol g(-1) for Mn-oxide after pretreatment with 10 mmol L(-1) K2SO3. The addition of 2.5 mmol L(-1) Mn(2+) also significantly improved Sb(V) adsorption, and the observed Qmax,Sb(V) increased to 1.4 and 1.0 mmol g(-1) for FMBO and Mn-oxide, respectively, with pre-adsorbed Mn(2+). Neither K2SO3 nor Mn(2+) addition had any effect on Sb(V) adsorption onto iron oxide (Fe-oxide). Mn(2+) introduced by either Mn(IV) dissolution or addition tended to form outer-sphere surface complexes with hydroxyl groups on Mn-oxide surfaces (MnOOH). Mn(2+) at 2.5 mmol L(-1) shifted the isoelectric point (pHiep) from 7.5 to 10.2 for FMBO and from 4.8 to 9.2 for Mn-oxide and hence benefited Sb(V) adsorption. The adsorption of Sb(V) onto Mn(2+)-enriched surfaces contributed to the release of Mn(2+), and the X-ray photoelectron spectra also indicated increased binding energy of Mn 2p3/2 after the adsorption of Sb(V) onto K2SO3-pretreated FMBO and Mn-oxide. Sb(V) adsorption involved the formation of inner-sphere complexes and contributed to the release of Mn(2+). In the removal of Sb(III) by Mn-based oxides, the oxidation of Sb(III) to Sb(V) by Mn(IV) oxides had an effect; however, Mn(IV) dissolution and Mn(2+)-enrichment also played an important role.

  10. Valence tautomerism in a high-valent manganese-oxo porphyrinoid complex induced by a Lewis acid.

    PubMed

    Leeladee, Pannee; Baglia, Regina A; Prokop, Katharine A; Latifi, Reza; de Visser, Sam P; Goldberg, David P

    2012-06-27

    Addition of the Lewis acid Zn(2+) to (TBP(8)Cz)Mn(V)(O) induces valence tautomerization, resulting in the formation of [(TBP(8)Cz(+•))Mn(IV)(O)-Zn(2+)]. This new species was characterized by UV-vis, EPR, the Evans method, and (1)H NMR and supported by DFT calculations. Removal of Zn(2+) quantitatively restores the starting material. Electron-transfer and hydrogen-atom-transfer reactions are strongly influenced by the presence of Zn(2+).

  11. Manganese-induced regulations in growth, yield formation, quality characters, rice aroma and enzyme involved in 2-acetyl-1-pyrroline biosynthesis in fragrant rice.

    PubMed

    Li, Meijuan; Ashraf, Umair; Tian, Hua; Mo, Zhaowen; Pan, Shenggang; Anjum, Shakeel Ahmad; Duan, Meiyang; Tang, Xiangru

    2016-06-01

    Micro-nutrient application is essential for normal plant growth while a little is known about manganese (Mn)-induced regulations in morpho-physiological attributes, aroma formation and enzyme involved in 2-acetyl-1-pyrroline (2-AP) biosynthesis in aromatic rice. Present study aimed to examine the influence of four levels of Mn i.e., Mn1 (100 mg MnSO4 pot(-1)), Mn2 (150 mg MnSO4 pot(-1)), Mn3 (200 mg MnSO4 pot(-1)), and Mn4 (250 mg MnSO4 pot(-1)) on the growth, yield formation, quality characters, rice aroma and enzyme involved in 2-acetyl-1-pyrroline biosynthesis in two fragrant rice cultivars i.e., Meixiangzhan and Nongxiang 18. Pots without Mn application were served as control (Ck). Each pot contained 15 kg of soil. Effects on agronomic characters, quality attributes, 2-AP contents and enzymes involved in 2-AP biosynthesis have been studied in early and late season rice. Results depicted that Mn improved rice growth, yield and related characters, and some quality attributes significantly. It further up-regulated proline, pyrroline-5-carboxylic acid (P5C) (precursors of 2-AP), soluble proteins and activities of proline dehydrogenase (ProDH), Δ(1) pyrroline-5-carboxylic acid synthetase (P5CS) ornithine aminotransferase (OAT) that led to enhanced 2-AP production in rice grains. Moreover, higher Mn levels resulted in increased grain Mn contents in both rice cultivars. Along with growth and yield improvement, Mn application significantly improved rice aromatic contents. Overall, Nongxiang 18 accumulated more 2-AP contents than Meixiangzhan in both seasons under Mn application. This study further explored the importance of Mn in rice aroma formation and signifies that micro-nutrients can play significant roles in rice aroma synthesis; however, intensive studies at molecular levels are still needed to understand the exact mechanisms of Mn to improve rice aroma formation. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  12. The role of cord blood BDNF in infant cognitive impairment induced by low-level prenatal manganese exposure: LW birth cohort, China.

    PubMed

    Yu, Xiaodan; Chen, Limei; Wang, Caifeng; Yang, Xin; Gao, Yu; Tian, Ying

    2016-11-01

    This study aimed to examine the potential association between low-level prenatal manganese (Mn) exposure and 1-year-old children's neurodevelopment quotient (DQ) by using the Gesell Developmental Inventory (GDI) (motor, adaptive, language, and social domains) and explored the role of brain-derived neurotrophic factor (BDNF) in Mn-induced cognitive impairments. A total of 377 mothers were recruited from a prospective birth cohort in rural northern China. Cord serum concentrations of Mn and BDNF were measured and children's DQ was evaluated. The median serum Mn concentration was 3.4 μg/L. After adjusting for confounding factors, Mn level was significantly associated with gross motor scores (β = -6.0, 95% CI: -11.8 to -0.2, p < 0.05) and personal-social scores (β = -4.2, 95% CI: -8.4 to 0.1, p < 0.05). BDNF level was positively correlated with personal-social score (β = 0.7, 95% CI: 0-1.4, p < 0.05). A significant correlation was found between Mn and BDNF (r = -0.13, 95% CI: -0.23 to -0.03, p < 0.01). Furthermore, the interaction between cord serum Mn and BDNF was significant (p < 0.001). In conclusion, elevated low-level prenatal Mn exposure impaired infant's neurodevelopment, and BDNF plays an important role in cognitive impairment, especially in the personal-social ability.

  13. [Function and disease in manganese].

    PubMed

    Kimura, Mieko

    2016-07-01

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

  14. Manganese oxide-induced strategy to high-performance iron/nitrogen/carbon electrocatalysts with highly exposed active sites

    NASA Astrophysics Data System (ADS)

    Sun, Tao; Wu, Qiang; Zhuo, Ou; Jiang, Yufei; Bu, Yongfeng; Yang, Lijun; Wang, Xizhang; Hu, Zheng

    2016-04-01

    Iron/nitrogen/carbon (Fe/N/C) catalyst is so far the most promising non-precious metal electrocatalyst for oxygen reduction reaction (ORR) in acidic medium, whose performance depends closely on the synthesis chemistry. Herein, we report a MnOx-induced strategy to construct the Fe/N/C with highly exposed Fe-Nx active sites, which involves the uniform spreading of polyaniline on hierarchical N-doped carbon nanocages by a reactive-template polymerization, followed by the successive iron incorporation and polyaniline pyrolysis. The resulting Fe/N/C demonstrates an excellent ORR performance, including an onset potential of 0.92 V (vs. RHE), four electron selectivity, superb stability and immunity to methanol crossover. The excellent performance is well correlated with the greatly enhanced surface active sites of the catalyst stemming from the unique MnOx-induced strategy. This study provides an efficient approach for exploring the advanced ORR electrocatalysts by increasing the exposed active sites.Iron/nitrogen/carbon (Fe/N/C) catalyst is so far the most promising non-precious metal electrocatalyst for oxygen reduction reaction (ORR) in acidic medium, whose performance depends closely on the synthesis chemistry. Herein, we report a MnOx-induced strategy to construct the Fe/N/C with highly exposed Fe-Nx active sites, which involves the uniform spreading of polyaniline on hierarchical N-doped carbon nanocages by a reactive-template polymerization, followed by the successive iron incorporation and polyaniline pyrolysis. The resulting Fe/N/C demonstrates an excellent ORR performance, including an onset potential of 0.92 V (vs. RHE), four electron selectivity, superb stability and immunity to methanol crossover. The excellent performance is well correlated with the greatly enhanced surface active sites of the catalyst stemming from the unique MnOx-induced strategy. This study provides an efficient approach for exploring the advanced ORR electrocatalysts by increasing the

  15. Recovery of zinc and manganese from spent batteries

    NASA Astrophysics Data System (ADS)

    Bartolozzi, Mauro; Braccini, Gaetano; Marconi, Filippo; Bonvini, Stefania

    1994-03-01

    The necessity of recycling spent batteries in order to recover metals and to protect the environment is emphasized. Some experiments have been made to develop a hydrometallurgical process for metal recovery in alkaline manganese batteries. The components are easily separated: zinc can be electroplated and manganese(II) can be oxidized to dioxide; Mn(IV) is solubilized in acidic hydrogen peroxide and reprecipitated by bases.

  16. Epicutaneous (EC) immunization with type II collagen (COLL II) induces CD4(+) CD8(+) T suppressor cells that protect from collagen-induced arthritis (CIA).

    PubMed

    Marcińska, Katarzyna; Majewska-Szczepanik, Monika; Lazar, Agata; Kowalczyk, Paulina; Biała, Dominika; Woźniak, Dorota; Szczepanik, Marian

    2016-04-01

    We have shown previously that epicutaneous (EC) immunization with protein antigen induces T suppressor cells that alleviate inflammatory response in contact hypersensitivity reactions, in an animal model of multiple sclerosis, and in TNBS-induced colitis. DBA/1 mice were EC immunized with type II collagen (COLL II) spread over a gauze patch on days 0 and 4. On day 7, patches were removed and mice were intradermally (id) immunized with COLL II in CFA to induce collagen-induced arthritis (CIA). Our work shows that EC immunization with 100μg of COLL II prior to CIA induction reduces disease severity as determined by macroscopic evaluation. Reduced disease severity after EC immunization with COLL II correlates with milder histological changes found in joint sections. Experiments with the three non-cross-reacting antigens COLL II, ovalbumin (OVA) and myelin basic protein (MBP) showed that skin-induced suppression is antigen non-specific. Transfer experiments show that EC immunization with COLL II induces suppressor cells that belong to the population of CD4(+) CD8(+) double positive lymphocytes. Flow cytometry experiments showed increased percentage of CD4(+) CD8(+) RORγt(+) cells in axillary and inguinal lymph nodes isolated from mice patched with COLL II. Maneuver of EC immunization with a protein antigen that induces suppressor cells to inhibit inflammatory responses may become an attractive, noninvasive, needle-free therapeutic method for different clinical situations. Copyright © 2015 Institute of Pharmacology, Polish Academy of Sciences. Published by Elsevier Urban & Partner Sp. z o.o. All rights reserved.

  17. A unique manganese (II) complex of 4-methoxy-pyridine-2-carboxylate: Synthesis, crystal structure, FT-IR and UV-Vis spectra and DFT calculations

    NASA Astrophysics Data System (ADS)

    Tamer, Ömer

    2017-09-01

    The first metal complex of 4-Methoxy-pyridine-2-carboxylic acid, [Mn(4-mpic)2(H2O)2], has been synthesized, and its crystal structure has been determined by X-Ray diffraction method. The FT-IR spectrum for [Mn(4-mpic)2(H2O)2] complex has been presented in this paper, as compared with that of single 4-mpic ligand. The electronic absorption spectrum recorded in DMSO solvent revealed that the ligand metal charge transfer (LMCT) interactions occur in Mn(II) complex. In order to support experimental results, density functional theory (DFT) calculations have been also carried out with the hybrid B3LYP functional. The coordination sphere of central Mn(II) ion has been evaluated by using the hyperconjugative interactions between the lone pair electrons of metal and donor atoms (N and O). The natural charge of Mn(II) ion demonstrated that the electronic transitions from metal ion to 4-mpic are higher than those in reverse direction. The carboxylate group has been determined as the most reactive side of Mn(II) complex in chemical reactions. A comparison among Mulliken, NBO and APT charges has been carried out for Mn(II) complex system. The first static hyperpolarizability parameter for Mn(II) complex has been also investigated by using B3LYP level.

  18. Permanganate-based synthesis of manganese oxide nanoparticles in ferritin

    NASA Astrophysics Data System (ADS)

    Olsen, Cameron R.; Smith, Trevor J.; Embley, Jacob S.; Maxfield, Jake H.; Hansen, Kameron R.; Peterson, J. Ryan; Henrichsen, Andrew M.; Erickson, Stephen D.; Buck, David C.; Colton, John S.; Watt, Richard K.

    2017-05-01

    This paper investigates the comproportionation reaction of MnII with {{{{MnO}}}4}- as a route for manganese oxide nanoparticle synthesis in the protein ferritin. We report that {{{{MnO}}}4}- serves as the electron acceptor and reacts with MnII in the presence of apoferritin to form manganese oxide cores inside the protein shell. Manganese loading into ferritin was studied under acidic, neutral, and basic conditions and the ratios of MnII and permanganate were varied at each pH. The manganese-containing ferritin samples were characterized by transmission electron microscopy, UV/Vis absorption, and by measuring the band gap energies for each sample. Manganese cores were deposited inside ferritin under both the acidic and basic conditions. All resulting manganese ferritin samples were found to be indirect band gap materials with band gap energies ranging from 1.01 to 1.34 eV. An increased UV/Vis absorption around 370 nm was observed for samples formed under acidic conditions, suggestive of MnO2 formation inside ferritin.

  19. Permanganate-Based Synthesis of Manganese Oxide Nanoparticles in Ferritin.

    PubMed

    Olsen, Cameron; Smith, Trevor; Embley, Jacob; Maxfield, Jake; Hansen, Kameron; Peterson, J; Henrichsen, Andrew; Erickson, Stephen; Buck, David; Colton, John S; Watt, Richard

    2017-03-23

    This paper investigates the comproportionation reaction of MnII with MnO4- as a route for manganese oxide nanoparticle synthesis in the protein ferritin. We report that MnO4- serves as the electron acceptor and reacts with MnII in the presence of apoferritin to form manganese oxide cores inside the protein shell. Manganese loading into ferritin was studied under acidic, neutral, and basic conditions and the ratios of MnII and permanganate were varied at each pH. The manganese-containing ferritin samples were characterized by transmission electron microscopy, UV/Vis absorption, and by measuring the band gap energies for each sample. Manganese cores were deposited inside ferritin under both the acidic and basic conditions. All resulting manganese ferritin samples were found to be indirect band gap materials with band gap energies ranging from 1.01 eV to 1.34 eV. An increased UV/Vis absorption around 370 nm was observed for samples formed under acidic conditions, suggestive of MnO2 formation inside ferritin.

  20. Angiotensin II induces differential insulin action in rat skeletal muscle.

    PubMed

    Surapongchai, Juthamard; Prasannarong, Mujalin; Bupha-Intr, Tepmanas; Saengsirisuwan, Vitoon

    2017-03-01

    Angiotensin II (ANGII) is reportedly involved in the development of skeletal muscle insulin resistance. The present investigation evaluated the effects of two ANGII doses on the phenotypic characteristics of insulin resistance syndrome and insulin action and signaling in rat skeletal muscle. Male Sprague-Dawley rats were infused with either saline (SHAM) or ANGII at a commonly used pressor dose (100 ng/kg/min; ANGII-100) or a higher pressor dose (500 ng/kg/min; ANGII-500) via osmotic minipumps for 14 days. We demonstrated that ANGII-100-infused rats exhibited the phenotypic features of non-obese insulin resistance syndrome, including hypertension, impaired glucose tolerance and insulin resistance of glucose uptake in the soleus muscle, whereas ANGII-500-treated rats exhibited diabetes-like symptoms, such as post-prandial hyperglycemia, impaired insulin secretion and hypertriglyceridemia. At the cellular level, insulin-stimulated glucose uptake in the soleus muscle of the ANGII-100 group was 33% lower (P < 0.05) than that in the SHAM group and was associated with increased insulin-stimulated IRS-1 Ser(307) and decreased Akt Ser(473) and AS160 Thr(642) phosphorylation and GLUT-4 expression. However, ANGII-500 infusion did not induce skeletal muscle insulin resistance or impair insulin signaling elements as initially anticipated. Moreover, we found that insulin-stimulated glucose uptake in the ANGII-500 group was accompanied by the enhanced expression of ACE2 and MasR proteins, which are the key elements in the non-classical pathway of the renin-angiotensin system. Collectively, this study demonstrates for the first time that chronic infusion with these two pressor doses of ANGII induced differential metabolic responses at both the systemic and skeletal muscle levels. © 2017 Society for Endocrinology.

  1. Manganese-Induced Oxidative DNA Damage in Neuronal SH-SY5Y Cells: Attenuation of thymine base lesions by glutathione and N-acetylcysteine

    PubMed Central

    Stephenson, Adrienne P.; Schneider, Jeffrey A.; Nelson, Bryant C.; Atha, Donald H.; Jain, Ashok; Soliman, Karam F. A.; Aschner, Michael; Mazzio, Elizabeth; Reams, R. Renee

    2013-01-01

    Manganese (Mn) is an essential trace element required for normal function and development. However, exposure to this metal at elevated levels may cause manganism, a progressive neurodegenerative disorder with neurological symptoms similar to idiopathic Parkinson’s disease (IPD). Elevated body burdens of Mn from exposure to parental nutrition, vapors in mines and smelters and welding fumes have been associated with neurological health concerns. The underlying mechanism of Mn neurotoxicity remains unclear. Accordingly, the present study was designed to investigate the toxic effects of Mn2+ in human neuroblastoma SH-SY5Y cells. Mn2+ caused a concentration dependent decrease in SH-SY5Y cellular viability compared to controls. The LD50 value was 12.98 μM Mn2+ (p <0.001 for control vs. 24h Mn treatment). Both TUNEL and annexin V/propidium iodide apoptosis assays confirmed the induction of apoptosis in the cells following exposure to Mn2+ (2 μM, 62 μM or 125 μM). In addition, Mn2+ induced both the formation and accumulation of DNA single strand breaks (via alkaline comet assay analysis) and oxidatively modified thymine bases (via gas chromatography/mass spectrometry analysis). Pre-incubation of the cells with characteristic antioxidants, either 1 mM N-acetylcysteine or 1 mM glutathione reduced the level of DNA strand breaks and the formation of thymine base lesions, suggesting protection against oxidative cellular damage. Our findings indicate that 1) exposure of SH-SY5Y cells to Mn promotes both the formation and accumulation of oxidative DNA nucleotide base damage, 2) SH-SY5Y cells with accumulated DNA damage are more likely to die via an apoptotic pathway and 3) the accumulated levels of DNA damage can be abrogated by the addition of exogenous chemical antioxidants. This is the first known report of Mn2+-induction and antioxidant protection of thymine lesions in this SH-SY5Y cell line and contributes new information to the potential use of antioxidants as a

  2. Hydrogen peroxide overload increases adriamycin-induced apoptosis of SaOS(2)FM, a manganese superoxide dismutase-overexpressing human osteosarcoma cell line.

    PubMed

    Wang, Yadi; Kuroda, Masahiro; Gao, Xian-Shu; Asaumi, Jun-Ichi; Shibuya, Kohichi; Kawasaki, Shoji; Akaki, Shiro; St Clair, Daret; Hiraki, Yoshio; Kanazawa, Susumu

    2005-05-01

    We previously developed a new microscopic observation system that enables time-lapse quantitative analysis of apoptosis and necrosis. With this system we quantitatively analyzed adriamycin (ADR)-induced cell death using manganese superoxide dismutase (MnSOD)- and wild-type p53-gene transfectants on SaOS(2), a p53-deficient human osteosarcoma cell line. A highly MnSOD-overexpressing cell line, SaOS(2)FM(H), acquired ADR-tolerance compared to the parent cell line SaOS(2). The ADR-tolerance of SaOS(2)FM(H) diminished by L-buthionine-[S,R]-sulfoximine (BSO), which did not change ADR-sensitivity of SaOS(2), to the similar ADR-sensitivity of SaOS(2). A wild-type p53-expressing cell line, SaOS(2)wtp53, significantly increased in ADR-sensitivity compared to SaOS(2). This ADR-sensitivity of SaOS(2)wtp53 was enhanced by BSO. When isosorbide 5-mononitrate was combined with BSO, isosorbide 5-mononitrate increased ADR sensitivity of a moderately MnSOD-overexpressing cell line, SaOS(2)FM(L), decreased that of SaOS(2) FM(H), and did not change those of SaOS(2) and SaOS(2)wtp53 compared to BSO alone. Time-lapse microscopic observations during ADR treatment for 24 h indicated that the most cells of each cell line underwent apoptosis, and a few cells (less than 11%) died by necrosis. When cells were treated with iso-concentration of ADR, apoptosis of SaOS(2)FM(H) was less than that of SaOS(2). BSO, which did not change ADR-sensitivity of SaOS(2), increased appearance rate of ADR-induced apoptosis, but not necrosis of MnSOD-overexpressing cell lines. When iso-survival dose of ADR, which reduced surviving fraction to 0.01, was given for each cell line, no difference was observed in appearance of either apoptosis or necrosis between SaOS(2) and MnSOD-overexpressing cell lines. On the other hands, appearance of both apoptosis and the following secondary necrosis of SaOS(2) wtp53 was significantly accelerated compared to those of SaOS(2). These findings indicate that hydrogen peroxide

  3. Complexation of Manganese with Glutarimidedioxime: Implication for Extraction Uranium from Seawater

    PubMed Central

    Xie, Xiang; Tian, Yin; Qin, Zhen; Yu, Qianhong; Wei, Hongyuan; Wang, Dongqi; Li, Xingliang; Wang, Xiaolin

    2017-01-01

    The molecule of glutaroimidedioxime, a cyclic imidedioxime moiety that can form during the synthesis of the poly(amidoxime)sorbent and is reputedly responsible for the extraction of uranium from seawater. Complexation of manganese (II) with glutarimidedioxime in aqueous solutions was investigated with potentiometry, calorimetry, ESI-mass spectrometry, electrochemical measurements and quantum chemical calculations. Results show that complexation reactions of manganese with glutarimidedioxime are both enthalpy and entropy driven processes, implying that the sorption of manganese on the glutarimidedioxime-functionalized sorbent would be enhanced at higher temperatures. Complex formation of manganese with glutarimidedioxime can assist redox of Mn(II/III). There are about ~15% of equilibrium manganese complex with the ligand in seawater pH(8.3), indicating that manganese could compete to some degree with uranium for sorption sites. PMID:28266579

  4. Complexation of Manganese with Glutarimidedioxime: Implication for Extraction Uranium from Seawater

    NASA Astrophysics Data System (ADS)

    Xie, Xiang; Tian, Yin; Qin, Zhen; Yu, Qianhong; Wei, Hongyuan; Wang, Dongqi; Li, Xingliang; Wang, Xiaolin

    2017-03-01

    The molecule of glutaroimidedioxime, a cyclic imidedioxime moiety that can form during the synthesis of the poly(amidoxime)sorbent and is reputedly responsible for the extraction of uranium from seawater. Complexation of manganese (II) with glutarimidedioxime in aqueous solutions was investigated with potentiometry, calorimetry, ESI-mass spectrometry, electrochemical measurements and quantum chemical calculations. Results show that complexation reactions of manganese with glutarimidedioxime are both enthalpy and entropy driven processes, implying that the sorption of manganese on the glutarimidedioxime-functionalized sorbent would be enhanced at higher temperatures. Complex formation of manganese with glutarimidedioxime can assist redox of Mn(II/III). There are about ~15% of equilibrium manganese complex with the ligand in seawater pH(8.3), indicating that manganese could compete to some degree with uranium for sorption sites.

  5. V-shaped ligand 1,3-bis(1-ethylbenzimidazol-2-yl)-2-thiapropane and manganese(II), cobalt(II) and copper(II) complexes: Synthesis, crystal structure, DNA-binding properties and antioxidant activities.

    PubMed

    Wu, Huilu; Yang, Zaihui; Wang, Fei; Peng, Hongping; Zhang, Han; Wang, Cuiping; Wang, Kaitong

    2015-07-01

    A V-shaped ligand 1,3-bis(1-ethylbenzimidazol-2-yl)-2-thiapropane (bebt) and its transition metal complexes, [Mn(bebt)(pic)2]·CH3OH (pic=picrate) 1, [Co(bebt)2](pic)22 and [Cu(bebt)2](pic)2·2DMF 3, have been synthesized and characterized. The coordinate forms of complexes 1 and 2 are basically alike, which can be described as six-coordinated distorted octahedron. The geometric structure around Cu(II) atom can be described as distorted tetrahedral in complex 3. The DNA-binding properties of the ligand bebt and complexes have been investigated by electronic absorption, fluorescence, and viscosity measurements. The results suggest that bebt and complexes bind to DNA via an intercalative binding mode and the order of the binding affinity is 1<2<3

  6. Direct identification of a bacterial manganese(II) oxidase, the multicopper oxidase MnxG, from spores of several different marine Bacillus species.

    PubMed

    Dick, Gregory J; Torpey, Justin W; Beveridge, Terry J; Tebo, Bradley M

    2008-03-01

    Microorganisms catalyze the formation of naturally occurring Mn oxides, but little is known about the biochemical mechanisms of this important biogeochemical process. We used tandem mass spectrometry to directly analyze the Mn(II)-oxidizing enzyme from marine Bacillus spores, identified as an Mn oxide band with an in-gel activity assay. Nine distinct peptides recovered from the Mn oxide band of two Bacillus species were unique to the multicopper oxidase MnxG, and one peptide was from the small hydrophobic protein MnxF. No other proteins were detected in the Mn oxide band, indicating that MnxG (or a MnxF/G complex) directly catalyzes biogenic Mn oxide formation. The Mn(II) oxidase was partially purified and found to be resistant to many proteases and active even at high concentrations of sodium dodecyl sulfate. Comparative analysis of the genes involved in Mn(II) oxidation from three diverse Bacillus species revealed a complement of conserved Cu-binding regions not present in well-characterized multicopper oxidases. Our results provide the first direct identification of a bacterial enzyme that catalyzes Mn(II) oxidation and suggest that MnxG catalyzes two sequential one-electron oxidations from Mn(II) to Mn(III) and from Mn(III) to Mn(IV), a novel type of reaction for a multicopper oxidase.

  7. Manganese As a Metal Accumulator

    EPA Science Inventory

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

  8. Manganese As a Metal Accumulator

    EPA Science Inventory

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

  9. Occupational exposure to manganese.

    PubMed Central

    Sarić, M; Markićević, A; Hrustić, O

    1977-01-01

    The relationship between the degree of exposure and biological effects of manganese was studied in a group of 369 workers employed in the production of ferroalloys. Two other groups of workers, from an electrode plant and from an aluminium rolling mill, served as controls. Mean manganese concentrations at work places where ferroalloys were produced varied from 0-301 to 20-442 mg/m3. The exposure level of the two control groups was from 2 to 30 microgram/m3 and from 0-05 to 0-07 microgram/m3, in the electrode plant and rolling mill respectively. Sixty-two (16-8%) manganese alloy workers showed some signs of neurological impairment. These signs were noticeably less in the two control groups (5-8% and 0%) than in the occupationally exposed group. Subjective symptoms, which are nonspecific but may be symptoms of subclinical manganism, were not markedly different in the three groups. However, in the manganese alloy workers some of the subjective symptoms occurred more frequently in heavier smokers than in light smokers or nonsmokers. Heavier smokers engaged in manganese alloy production showed some of the subjective symptoms more often than heavier smokers from the control groups. PMID:871441

  10. Angiotensin II enhances endothelin-1-induced vasoconstriction through upregulating endothelin type A receptor.

    PubMed

    Lin, Yan-Jie; Kwok, Ching-Fai; Juan, Chi-Chang; Hsu, Yung-Pei; Shih, Kuang-Chung; Chen, Chin-Chang; Ho, Low-Tone

    2014-08-22

    Endothelin-1 (ET-1) is the most potent vasoconstrictor by binding to endothelin receptors (ETAR) in vascular smooth muscle cells (VSMCs). The complex of angiotensin II (Ang II) and Ang II type one receptor (AT1R) acts as a transient constrictor of VSMCs. The synergistic effect of ET-1 and Ang II on blood pressure has been observed in rats; however, the underlying mechanism remains unclear. We hypothesize that Ang II leads to enhancing ET-1-mediated vasoconstriction through the activation of endothelin receptor in VSMCs. The ET-1-induced vasoconstriction, ET-1 binding, and endothelin receptor expression were explored in the isolated endothelium-denuded aortae and A-10 VSMCs. Ang II pretreatment enhanced ET-1-induced vasoconstriction and ET-1 binding to the aorta. Ang II enhanced ETAR expression, but not ETBR, in aorta and increased ET-1 binding, mainly to ETAR in A-10 VSMCs. Moreover, Ang II-enhanced ETAR expression was blunted and ET-1 binding was reduced by AT1R antagonism or by inhibitors of PKC or ERK individually. In conclusion, Ang II enhances ET-1-induced vasoconstriction by upregulating ETAR expression and ET-1/ETAR binding, which may be because of the AngII/Ang II receptor pathways and the activation of PKC or ERK. These findings suggest the synergistic effect of Ang II and ET-1 on the pathogenic development of hypertension. Copyright © 2014 Elsevier Inc. All rights reserved.

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

    SciTech Connect

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

    1998-10-01

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

  12. Manganese Research Health Project (MHRP)

    DTIC Science & Technology

    2006-01-01

    MRI) of Manganese Role of Manganese in Prion Disease Pathogenesis Accumulation in the Rat Brain Associated with Iron - Deficiency and Supplementation...Imaging (MRI) of Manganese Accumulation in the Rat Brain Associated with Iron -Deficiency and Supplementation Aschner, Michael, Ph.D. Fitsanakis, Vanessa...Aschner (2006). Determination of brain manganese and iron accumulation using magnetic resonance imaging (MRI) and atomic absorption spectroscopy. 4 2 nd

  13. Probing the topography of the photosystem II oxygen evolving complex: PsbO is required for efficient calcium protection of the manganese cluster against dark-inhibition by an artificial reductant.

    PubMed

    Popelkova, Hana; Boswell, Nicholas; Yocum, Charles

    2011-12-01

    The photosystem II (PSII) manganese-stabilizing protein (PsbO) is known to be the essential PSII extrinsic subunit for stabilization and retention of the Mn and Cl(-) cofactors in the oxygen evolving complex (OEC) of PSII, but its function relative to Ca(2+) is less clear. To obtain a better insight into the relationship, if any, between PsbO and Ca(2+) binding in the OEC, samples with altered PsbO-PSII binding properties were probed for their potential to promote the ability of Ca(2+) to protect the Mn cluster against dark-inhibition by an exogenous artificial reductant, N,N-dimethylhydroxylamine. In the absence of the PsbP and PsbQ extrinsic subunits, Ca(2+) and its surrogates (Sr(2+), Cd(2+)) shield Mn atoms from inhibitory reduction (Kuntzleman et al., Phys Chem Chem Phys 6:4897, 2004). The results presented here show that PsbO exhibits a positive effect on Ca(2+) binding in the OEC by facilitating the ability of the metal to prevent inhibition of activity by the reductant. The data presented here suggest that PsbO may have a role in the formation of the OEC-associated Ca(2+) binding site by promoting the equilibrium between bound and free Ca(2+) that favors the bound metal.

  14. Electrochemical deposition of the new manganese(II) Schiff-base complex on a gold template and its application for dopamine sensing in the presence of interfering biogenic compounds.

    PubMed

    Gorczyński, Adam; Pakulski, Dawid; Szymańska, Martyna; Kubicki, Maciej; Bułat, Kornela; Łuczak, Teresa; Patroniak, Violetta

    2016-01-01

    Facile and efficient template synthesis of new manganese(II) complex [Mn2(H2L)2](ClO4)2 (1) and its crystal structure are reported. Self-assembly leads to the formation of dinuclear, phenoxo-bridged closed species via exploitation of both binding subunits of the in situ formed new Schiff-base ligand. Gold electrode modified with self-assembled monolayers (SAMs) composed of synthesized complex 1 was applied as a voltammetric sensor for quantitative determination of dopamine (DA) in the presence of ascorbic (AA) and uric acids (UA). The linear relationship between the current response of dopamine at the potential of peak maximum and the concentration was found over a wide analyte concentration range (R(2)≥0.993, 1×10(-10)-8.5×10(-4)M) with a very good sensitivity (4.11Acm(-2)M(-1) at dE/dt=0.1Vs(-1)), high detection limit (6.8×10(-9)M) and excellent reproducibility. It has been proven that current peaks of dopamine, ascorbic and uric acids were clearly separated from each other, thus enabling selective detection of these compounds coexisting in a mixture.

  15. A click fluorophore sensor that can distinguish Cu(II) and Hg(II) via selective anion-induced demetallation.

    PubMed

    Lau, Yu Heng; Price, Jason R; Todd, Matthew H; Rutledge, Peter J

    2011-03-01

    A cyclam-based fluorescent sensor featuring a novel triazole pendant arm has been synthesised using click chemistry. The sensor is highly responsive to both Cu(II) and Hg(II) in neutral aqueous solution and displays excellent selectivity in the presence of various competing metal ions in 50-fold excess. The addition of specific anions such as I(-) and S(2)O(3)(2-) causes a complete revival of fluorescence only in the case of Hg(II), providing a simple and effective method for distinguishing solutions containing Cu(II), Hg(II) or a mixture of both ions, even in doped seawater samples. X-ray crystal structures of both the Hg(II) sensor complex and a model Cu(II) complex show that pendant triazole coordination occurs through the central nitrogen atom (N2), providing to the best of our knowledge the first reported examples of this unusual coordination mode in macrocycles. Fluorescence, mass spectrometry and (1)H NMR experiments reveal that the mechanism of anion-induced fluorescence revival involves either displacement of pendant coordination or complete removal of the Hg(II) from the macrocycle, depending on the anion.

  16. Manganese biomining: A review.

    PubMed

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

    2011-08-01

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

  17. Nitric Oxide Inhibits Topoisomerase II Activity and Induces Resistance to Topoisomerase II-Poisons in Human Tumor Cells

    PubMed Central

    Kumar, Ashutosh; Ehrenshaft, Marilyn; Tokar, Erik J.; Mason, Ronald P.; Sinha, Birandra K.

    2016-01-01

    Background Etoposide and doxorubicin, topoisomerase II poisons, are important drugs for the treatment of tumors in the clinic. Topoisomerases contain several free sulfhydryl groups which are important for their activity and are also potential targets for nitric oxide (•NO)-induced nitrosation. •NO, a physiological signaling molecule nitrosates many cellular proteins, causing altered protein and cellular functions. Methods Here, we have evaluated the roles of •NO/•NO-derived species in the activity stability of topo II both in vitro and in human tumor cells, and in the cytotoxicity of topo II-poisons, etoposide and doxorubicin. Results Treatment of purified topo IIα with propylamine propylamine nonoate (PPNO), an •NO donor, resulted in inhibition of both the catalytic and relaxation activity in vitro, and decreased etoposide-dependent cleavable complex formation in both human HT-29 colon and MCF-7 breast cancer cells. PPNO treatment also induced significant nitrosation of topo IIα protein in these human tumor cells. These events, taken together, caused a significant resistance to etoposide in both cell lines. However, PPNO had no effect on doxorubicin-induced cleavable complex formation, or doxorubicin cytotoxicity in these cell lines. Conclusion Inhibition of topo II function by •NO/•NO-derived species induces significant resistance to etoposide, without affecting doxorubicin cytotoxicity in human tumor cells. General Significance As tumors express inducible nitric oxide synthase and generate significant amounts of •NO, modulation of topo II functions by •NO/•NO-derived species could render tumors resistant to certain topo II-poisons in the clinic. PMID:27095671

  18. Taurine improves the spatial learning and memory ability impaired by sub-chronic manganese exposure

    PubMed Central

    2014-01-01

    Background Excessive manganese exposure induced cognitive deficit. Several lines of evidence have demonstrated that taurine improves cognitive impairment induced by numerous neurotoxins. However, the role of taurine on manganese-induced damages in learning and memory is still elusive. This goal of this study was to investigate the beneficial effect of taurine on learning and memory capacity impairment by manganese exposure in an animal model. Results The escape latency in the Morris Water Maze test was significantly longer in the rats injected with manganese than that in the rats received both taurine and manganese. Similarly, the probe trial showed that the annulus crossings were significantly greater in the taurine plus manganese treated rats than those in the manganese-treated rats. However, the blood level of manganese was not altered by the taurine treatment. Interestingly, the exposure of manganese led to a significant increase in the acetylcholinesterase activity and an evidently decrease in the choline acetyltransferase activity, which were partially restored by the addition of taurine. Additionally, we identified 9 differentially expressed proteins between the rat hippocampus treated by manganese and the control or the manganese plus taurine in the proteomic analysis using the 2-dimensional gel electrophoresis followed by the tandem mass spectrometry (MS/MS). Most of these proteins play a role in energy metabolism, oxidative stress, inflammation, and neuron synapse. Conclusions In summary, taurine restores the activity of AChE and ChAT, which are critical for the regulation of acetylcholine. We have identified seven differentially expressed proteins specifically induced by manganese and two proteins induced by taurine from the rat hippocampus. Our results support that taurine improves the impaired learning and memory ability caused by excessive exposure of manganese. PMID:24885898

  19. Taurine improves the spatial learning and memory ability impaired by sub-chronic manganese exposure.

    PubMed

    Lu, Cai-Ling; Tang, Shen; Meng, Zhi-Juan; He, Yi-Yuan; Song, Ling-Yong; Liu, Yin-Pin; Ma, Ning; Li, Xi-Yi; Guo, Song-Chao

    2014-05-24

    Excessive manganese exposure induced cognitive deficit. Several lines of evidence have demonstrated that taurine improves cognitive impairment induced by numerous neurotoxins. However, the role of taurine on manganese-induced damages in learning and memory is still elusive. This goal of this study was to investigate the beneficial effect of taurine on learning and memory capacity impairment by manganese exposure in an animal model. The escape latency in the Morris Water Maze test was significantly longer in the rats injected with manganese than that in the rats received both taurine and manganese. Similarly, the probe trial showed that the annulus crossings were significantly greater in the taurine plus manganese treated rats than those in the manganese-treated rats. However, the blood level of manganese was not altered by the taurine treatment. Interestingly, the exposure of manganese led to a significant increase in the acetylcholinesterase activity and an evidently decrease in the choline acetyltransferase activity, which were partially restored by the addition of taurine. Additionally, we identified 9 differentially expressed proteins between the rat hippocampus treated by manganese and the control or the manganese plus taurine in the proteomic analysis using the 2-dimensional gel electrophoresis followed by the tandem mass spectrometry (MS/MS). Most of these proteins play a role in energy metabolism, oxidative stress, inflammation, and neuron synapse. In summary, taurine restores the activity of AChE and ChAT, which are critical for the regulation of acetylcholine. We have identified seven differentially expressed proteins specifically induced by manganese and two proteins induced by taurine from the rat hippocampus. Our results support that taurine improves the impaired learning and memory ability caused by excessive exposure of manganese.

  20. Eclalbasaponin II induces autophagic and apoptotic cell death in human ovarian cancer cells.

    PubMed

    Cho, Yoon Jin; Woo, Jeong-Hwa; Lee, Jae-Seung; Jang, Dae Sik; Lee, Kyung-Tae; Choi, Jung-Hye

    2016-09-01

    Triterpenoids echinocystic acid and its glycosides, isolated from several Eclipta prostrata, have been reported to possess various biological activities such as anti-inflammatory, anti-bacterial, and anti-diabetic activity. However, the cytotoxicity of the triterpenoids in human cancer cells and their molecular mechanism of action are poorly understood. In the present study, we found that eclalbasaponin II with one glucose moiety has potent cytotoxicity in three ovarian cancer cells and two endometrial cancer cells compared to an aglycone echinocystic acid and eclalbasaponin I with two glucose moiety. Eclalbasaponin II treatment dose-dependently increased sub G1 population. Annexin V staining revealed that eclalbasaponin II induced apoptosis in SKOV3 and A2780 ovarian cancer cells. In addition, eclalbasaponin II-induced cell death was associated with characteristics of autophagy; an increase in acidic vesicular organelle content and elevation of the levels of LC3-II. Interestingly, autophagy inhibitor BaF1 suppressed the eclalbasaponin II-induced apoptosis. Moreover, eclalbasaponin II activated JNK and p38 signaling and inhibited the mTOR signaling. We further demonstrated that pre-treatment with a JNK and p38 inhibitor and mTOR activator attenuated the eclalbasaponin II-induced autophagy. This suggests that eclalbasaponin II induces apoptotic and autophagic cell death through the regulation of JNK, p38, and mTOR signaling in human ovarian cancer cells. Copyright © 2016 The Authors. Production and hosting by Elsevier B.V. All rights reserved.

  1. Renal denervation attenuates aldosterone expression and associated cardiovascular pathophysiology in angiotensin II-induced hypertension

    PubMed Central

    Chen, Dong-Rui; Ruan, Cheng-Chao; Xu, Jian-Zhong; Chen, Jing; Wu, Yong-Jie; Ma, Yu; Zhu, Ding-Liang; Gao, Ping-Jin

    2016-01-01

    The sympathetic nervous system interacts with the renin-angiotensin-aldosterone system (RAAS) contributing to cardiovascular diseases. In this study, we sought to determine if renal denervation (RDN) inhibits aldosterone expression and associated cardiovascular pathophysiological changes in angiotensin II (Ang II)-induced hypertension. Bilateral RDN or SHAM operation was performed before chronic 14-day Ang II subcutaneous infusion (200ng/kg/min) in male Sprague-Dawley rats. Bilateral RDN blunted Ang II-induced hypertension and ameliorated the mesenteric vascular dysfunction. Cardiovascular hypertrophy in response to Ang II was significantly attenuated by RDN as shown by histopathology and transthoracic echocardiography. Moreover, Ang II-induced vascular and myocardial inflammation and fibrosis were suppressed by RDN with concurrent decrease in fibronectin and collagen deposition, macrophage infiltration, and MCP-1 expression. Interestingly, RDN also inhibited Ang II-induced aldosterone expression in the plasma, kidney and heart. This was associated with the reduction of calcitonin gene-related peptide (CGRP) in the adrenal gland. Ang II promoted aldosterone secretion which was partly attenuated by CGRP in the adrenocortical cell line, suggesting a protective role of CGRP in this model. Activation of transforming growth factor-β (TGF-β)/Smad and mitogen-activated protein kinases (MAPKs) signaling pathway was both inhibited by RDN especially in the heart. These results suggest that the regulation of the renal sympathetic nerve in Ang II-induced hypertension and associated cardiovascular pathophysiological changes is likely mediated by aldosterone, with CGRP involvement. PMID:27661131

  2. Manganese-based complexes of radical scavengers as neuroprotective agents.

    PubMed

    Vajragupta, Opa; Boonchoong, Preecha; Sumanont, Yaowared; Watanabe, Hiroshi; Wongkrajang, Yuvadee; Kammasud, Naparat

    2003-05-15

    Manganese was incorporated in the structure of the selected antioxidants to mimic the superoxide dismutase (SOD) and to increase radical scavenging ability. Five manganese complexes (1-5) showed potent SOD activity in vitro with IC(50) of 1.18-1.84 microM and action against lipid peroxidation in vitro with IC(50) of 1.97-8.00 microM greater than their ligands and trolox. The manganese complexes were initially tested in vivo at 50 mg/kg for antagonistic activity on methamphetamine (MAP)-induced hypermotility resulting from dopamine release in the mice brain. Only manganese complexes of kojic acid (1) and 7-hydroxyflavone (3) exhibited the significant suppressions on MAP-induced hypermotility and did not significantly decrease the locomotor activity in normal condition. Manganese complex 3 also showed protective effects against learning and memory impairment in transient cerebral ischemic mice. These results supported the brain delivery and the role of manganese in SOD activity as well as in the modulation of brain neurotransmitters in the aberrant condition. Manganese complex 3 from 7-hydroxyflavone was the promising candidate for radical implicated neurodegenerative diseases.

  3. Contribution of Ca^{2+} ions influx in Cu (II) or Cr (VI) induced hepatocyte cytotoxicity

    NASA Astrophysics Data System (ADS)

    Pourahmad, J.; O'Brien, P. J.

    2003-05-01

    Previously we showed that hepatocyte lysis induced by Cu (II) or Cr (VI) could be partly attributed to membrane lipid peroxidation induced by Cu (II) or Cr (VI) [1, 2]. Changes in Na^+ and Ca^{+2} homeostasis induced when Cu^{+2} or Cr VI were incubated with hepatocytes. Na^+ omission from the media or addition of the Na^+/H^+ exchange inhibitor 5-(N, N-dimethyl)-amiloride markedly increased Cu (II) or Cr (VI) cytotoxicity even though Cu (II) or Cr (VI) did not increase hepatocyte Na^+ when the media contained Na^+. The omission of CI^- from the media or addition of glycine, a CI^- channel blocker also enhanced Cu (II) or Cr (VI) induced cytotoxicity. Intracellular Ca^{+2} levels however were markedly increased when the hepatocytes were incubated with Cu^{+2} or Cr VI in a Na^+ free media and removing media Ca^{+2} with EGTA also prevented Cu (II) or Cr (VI) induced hepatocyte cytotoxicity. This suggests that intracellular Ca^{+2} accumulation contributes to Cu (II) or Cr (VI) induced cytotoxicity and a Na^+_- dependent Ca^{+2} transporter is involved in controlling excessive Ca^{+2} accumulation caused by Cu (II) or Cr (VI).

  4. Three Unique Barium Manganese Vanadates from High-Temperature Hydrothermal Brines.

    PubMed

    Smith Pellizzeri, Tiffany M; McMillen, Colin D; Wen, Yimei; Chumanov, George; Kolis, Joseph W

    2017-04-03

    Three new barium manganese vanadates, all containing hexagonal barium chloride layers interpenetrated by [V2O7](4-) groups, were synthesized using a high-temperature (580 °C) hydrothermal method. Two of the compounds were prepared from a mixed BaCl2/Ba(OH)2 mineralizer, and the third compound was prepared from BaCl2 mineralizer. An interesting structural similarity exists between two of the compounds, Ba2Mn(V2O7)(OH)Cl and Ba4Mn2(V2O7)(VO4)2O(OH)Cl. These two compounds crystallize in the orthorhombic space group Pnma, Z = 4, and are structurally related by a nearly doubled a axis. The first structure, Ba2Mn(V2O7)(OH)Cl (I) (a = 15.097(3) Å, b = 6.1087(12) Å, c = 9.5599(19) Å), consists of octahedral manganese(II) edge-sharing chains linked by pyrovanadate [V2O7] groups, generating a three-dime