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52. The endothelium-derived hyperpolarizing factor, [H.sub.2][O.sub.2] promotes metal-ion efflux in aortic endothelial cells: Elemental mapping by a hard X-ray microprobe

Author

Witting, Paul K., Harris, Hugh H., Rayner, Benjamin S., Aitken, Jade B., Dillon, Carolyn T., Stocker, Roland, Barry, Lai, Cai, Zhonghou, and Lay, Peter A.

Subjects
Endothelium -- Research, Cytoplasm -- Research, Spectrum analysis -- Usage, Biological sciences, Chemistry
Abstract

Submicrometer-resolution hard X-ray elemental mapping of cultured peroine aortic endothelial cells (PAEC) has provided data on the global changes for intracellular elemental density within PAEC and indicates an efflux of metal ions and phosphorus from the cytoplasm after [H.sub.2][O.sub.2] treatment. The synchrotron-radiation induced X-ray emission experiments (SRIXE) show that [H.sub.2][O.sub.2] treated cells are irregularly shaped and exhibit blebbing indicative of increased permeability due to the damaged membrane.

Published
2006

53. Charge distribution in chromium and vanadium catecholato complexes: X-ray absorption spectroscopic and computational studies

Author

Milsmann, Carsten, Foran, Garry J., Levina, Aviva, Harris, Hugh H., Lay, Peter A., and Turner, Peter

Subjects
Density functionals -- Research, Absorption spectra -- Analysis, Chromium compounds -- Electric properties, Electrochemistry -- Analysis, Chemistry
Abstract

The density functional theory (DFT) technique is used for the computational studies on Cr and V triscatecholato complexes and the results are used to help in the interpretation of electrochemical X-ray absorption spectroscopy (XAS) data. The results have suggested that Cr(IV) and Cr(V) complexes, stabilized by electron delocalization between the Cr ion and the ligands, are formed during the oxidation of Cr(III) triscatecholato complexes or during the reduction of Cr(VI) by catechols.

Published
2006

56. PBT2 acts through a different mechanism of action than other 8-hydroxyquinolines: an X-ray fluorescence imaging study

Author

Summers, Kelly L, primary, Dolgova, Natalia V, additional, Gagnon, Kenneth B, additional, Sopasis, George J, additional, James, Ashley K, additional, Lai, Barry, additional, Sylvain, Nicole J, additional, Harris, Hugh H, additional, Nichol, Helen K, additional, George, Graham N, additional, and Pickering, Ingrid J, additional

Published
2020
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57. Synthesis, purification, and structural characterization of the dimethyldiselenoarsinate anion

Author

Gailer, Jurgen, George, Graham N., Harris, Hugh H., Pickering, Ingrid J., Prince, Roger C., Somogyi, Arpad, Buttigieg, Gavin A., Glass, Richard S., and Denton, M. Bonner

Subjects
Chemistry, Inorganic -- Research, Anions, Solution (Chemistry), Sodium, Selenium compounds, Chemistry
Abstract

Research has been conducted on the arsenic-selenium solution species. The synthesis of these species carried out in equimolar sodium selenite and sodium dimethylarsinate in aqueous solution is described.

Published
2002

58. Metal cyanide ions M(sub)x(CN)(sub)y](sup)+,- in the gas phase: M=Fe, Co, Ni, Zn, Cd, Hg, Fe + Ag, C0+Ag

Author

Dance, Ian G., Dean, Philip A.W., Fisher, Keith J., and Harris, Hugh H.

Subjects
Inorganic compounds -- Synthesis, Laser beams -- Usage, Coordination compounds -- Analysis, Cyanides -- Analysis, Chemical structure -- Analysis, Chemistry
Abstract

Research discusses the preparation of metal cyanide ions in the gas phase by laser ablation of cyano-metalate complexes. Results show that excepting the complexes containing zinc or cadmium metal component, other cyano-metalate complexes, used as precursors, yield a lower metal oxidation state than that of the precursors.

Published
2002

59. Structures of the cuprous-thiolate clusters of the Mac1 and Ace1 transcriptional activators

Author

Brown, Kenneth R., Keller, Greg L., Pickering, Ingrid J., Harris, Hugh H., George, Graham N., and Winge, Dennis R.

Subjects
Biochemistry -- Research, Copper -- Physiological aspects, Genetic transcription -- Physiological aspects, Bacterial proteins -- Genetic aspects, Brewer's yeast -- Genetic aspects, Biological sciences, Chemistry
Abstract

Research has been conducted on Saccharomyces cerevisiae copper-regulated transcription factors. Results indicate that copper-sensing nuclear transcription regulators in S. cerevisiae contain polycopper thiolate clusters.

Published
2002

65. Potent Inhibition of Thioredoxin Reductase by the Rh Derivatives of Anticancer M(arene/Cp*)(NHC)Cl2 Complexes

Author

Truong, Dianna, primary, Sullivan, Matthew P., additional, Tong, Kelvin K. H., additional, Steel, Tasha R., additional, Prause, Andre, additional, Lovett, James H., additional, Andersen, Jake W., additional, Jamieson, Stephen M.F., additional, Harris, Hugh H., additional, Ott, Ingo, additional, Weekley, Claire M., additional, Hummitzsch, Katja, additional, Söhnel, Tilo, additional, Hanif, Muhammad, additional, Metzler-Nolte, Nils, additional, Goldstone, David C., additional, and Hartinger, Christian G., additional

Published
2020
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68. Confocal Volumetric μXRF and Fluorescence Computed μ-Tomography Reveals Arsenic Three-Dimensional Distribution within Intact Pteris vittata Fronds

Author

van der Ent, Antony, primary, de Jonge, Martin D., additional, Spiers, Kathryn M., additional, Brueckner, Dennis, additional, Montargès-Pelletier, Emmanuelle, additional, Echevarria, Guillaume, additional, Wan, Xiao-Ming, additional, Lei, Mei, additional, Mak, Rachel, additional, Lovett, James H., additional, and Harris, Hugh H., additional

Published
2019
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69. Abnormal concentrations of Cu-Co in : Haumaniastrum katangense, Haumaniastrum robertii and Aeolanthus biformifolius: Contamination or hyperaccumulation?

Author

Van Der Ent, Antony, Malaisse, François, Erskine, Peter D., Mesjasz-Przybyłowicz, Jolanta, Przybyłowicz, Wojciech J., Barnabas, Alban D., Sośnicka, Marta, Harris, Hugh H., Van Der Ent, Antony, Malaisse, François, Erskine, Peter D., Mesjasz-Przybyłowicz, Jolanta, Przybyłowicz, Wojciech J., Barnabas, Alban D., Sośnicka, Marta, and Harris, Hugh H.

Abstract

The Central African Copperbelt of the DR Congo and Zambia hosts more than 30 known Cu-Co hyperaccumulator plant species. These plants can accumulate extraordinarily high concentrations of Cu and Co in their living tissues without showing any signs of toxicity. Haumaniastrum robertii is the most extreme Co hyperaccumulator (able to accumulate up to 1 wt% Co), whereas Aeolanthus biformifolius is the most extreme Cu hyperaccumulator (with up to 1 wt% Cu). The phenomenon of Cu-Co hyperaccumulator plants was studied intensively in the 1970s through to the 1990s, but doubts arose regarding earlier observations due to surficial contamination of plant material with mineral particles. This study set out to determine whether such extraneous contamination could be observed on herbarium specimens of Haumaniastrum robertii and Aeolanthus biformifolius using scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS). Further, synchrotron X-ray absorption spectroscopy (XAS) was used to identify the chemical forms of Cu and Co in newly collected Haumaniastrum katangense plant material from the DR Congo. The results show that surficial contamination is not the cause for abnormal Cu-Co concentrations in the plant material, but rather that Cu-Co enrichment is endogenous. The chemical form of Cu and Co (complexation with carboxylic acids) provides additional evidence that genuine hyperaccumulation, and not soil mineral contamination, is responsible for extreme tissue concentrations of Cu and Co in Haumaniastrum katangense.

Published
2019

75. High-resolution EXAFS of the active site of human sulfite oxidase: Comparison with density functional theory and x-ray crystallographic results

Author

George, Graham N., Harris, Hugh H., and Rajagopalan, K.V.

Subjects
Sulfites -- Electric properties, Density functionals -- Research, Hydroxides -- Research, Chemistry
Abstract

A study of the active site of sulfite oxidase is presented to overcome limited resolution of (XAS) X-ray absorption spectroscopy by significantly extending the data range. The combined EXAFS and density functional theory results indicate that the equatorial O-donor ligand in the reduced form of human sulfite oxidase is water and not a hydroxide.

Published
2006

77. X-ray elemental mapping techniques for elucidating the ecophysiology of hyperaccumulator plants

Author

van der Ent, Antony, Przybyłowicz, Wojciech J., de Jonge, Martin D., Harris, Hugh H., Ryan, Chris G., Tylko, Grzegorz, Paterson, David J., Barnabas, Alban D., Kopittke, Peter M., Mesjasz-Przybyłowicz, Jolanta, van der Ent, Antony, Przybyłowicz, Wojciech J., de Jonge, Martin D., Harris, Hugh H., Ryan, Chris G., Tylko, Grzegorz, Paterson, David J., Barnabas, Alban D., Kopittke, Peter M., and Mesjasz-Przybyłowicz, Jolanta

Abstract

(Table presented.). Summary: Hyperaccumulators are attractive models for studying metal(loid) homeostasis, and probing the spatial distribution and coordination chemistry of metal(loid)s in their tissues is important for advancing our understanding of their ecophysiology. X-ray elemental mapping techniques are unique in providing in situ information, and with appropriate sample preparation offer results true to biological conditions of the living plant. The common platform of these techniques is a reliance on characteristic X-rays of elements present in a sample, excited either by electrons (scanning/transmission electron microscopy), protons (proton-induced X-ray emission) or X-rays (X-ray fluorescence microscopy). Elucidating the cellular and tissue-level distribution of metal(loid)s is inherently challenging and accurate X-ray analysis places strict demands on sample collection, preparation and analytical conditions, to avoid elemental redistribution, chemical modification or ultrastructural alterations. We compare the merits and limitations of the individual techniques, and focus on the optimal field of applications for inferring ecophysiological processes in hyperaccumulator plants. X-ray elemental mapping techniques can play a key role in answering questions at every level of metal(loid) homeostasis in plants, from the rhizosphere interface, to uptake pathways in the roots and shoots. Further improvements in technological capabilities offer exciting perspectives for the study of hyperaccumulator plants into the future.

Published
2018

79. Nickel biopathways in tropical nickel hyperaccumulating trees from Sabah (Malaysia)

Author

van der Ent, Antony, Callahan, Damien L., Noller, Barry N., Mesjasz-Przybylowicz, Jolanta, Przybylowicz, Wojciech J., Barnabas, Alban, Harris, Hugh H., van der Ent, Antony, Callahan, Damien L., Noller, Barry N., Mesjasz-Przybylowicz, Jolanta, Przybylowicz, Wojciech J., Barnabas, Alban, and Harris, Hugh H.

Abstract

The extraordinary level of accumulation of nickel (Ni) in hyperaccumulator plants is a consequence of specific metal sequestering and transport mechanisms, and knowledge of these processes is critical for advancing an understanding of transition element metabolic regulation in these plants. The Ni biopathways were elucidated in three plant species, Phyllanthus balgooyi, Phyllanthus securinegioides (Phyllanthaceae) and Rinorea bengalensis (Violaceae), that occur in Sabah (Malaysia) on the Island of Borneo. This study showed that Ni is mainly concentrated in the phloem in roots and stems (up to 16.9% Ni in phloem sap in Phyllanthus balgooyi) in all three species. However, the species differ in their leaves - in P. balgooyi the highest Ni concentration is in the phloem, but in P. securinegioides and R. bengalensis in the epidermis and in the spongy mesophyll (R. bengalensis). The chemical speciation of Ni 2+ does not substantially differ between the species nor between the plant tissues and transport fluids, and is unambiguously associated with citrate. This study combines ion microbeam (PIXE and RBS) and metabolomics techniques (GC-MS, LC-MS) with synchrotron methods (XAS) to overcome the drawbacks of the individual techniques to quantitatively determine Ni distribution and Ni 2+ chemical speciation in hyperaccumulator plants.

Published
2017

80. Localizing the chemical forms of sulfur in vivo using x-ray fluorescence spectroscopic imaging: application to onion (Allium cepa) tissues

Author

Pickering, Ingrid J., Sneeden, Eileen Yu, Prince, Roger C., Block, Eric, Harris, Hugh H., Hirsch, Gregory, and George, Graham N.

Subjects
Fluorescence spectroscopy -- Usage, Onions -- Research, Sulfur -- Research, Plant cells and tissues -- Research, Biological sciences, Chemistry
Abstract

An extended and modified version of sulfur K-edge x-ray fluorescence spectroscopic imaging as an in vivo probe of sulfur metabolism in living cells based on onion (Allium cepa) as a tractable model system is reported. X-ray fluorescence spectroscopic imaging showed elevated levels of sulfoxides in the cytosol and elevated levels of reduced sulfur in the central transport vessels and bundle sheath cells.

Published
2009

81. X-ray absorption and EPR spectroscopic studies of the biotransformations of chromium(VI) in mammalian cell. Is chromodulin an artifact of isolation methods?

Author

Levina, Aviva, Harris, Hugh H., and Lay, Peter A.

Subjects
Chromium (Nutrient) -- Physiological aspects, Chromium (Nutrient) -- Chemical properties, Electron donor-acceptor complexes -- Analysis, Chemistry
Abstract

A study conducted shows that X-ray absorption near-edge structure (XANES) spectroscopy has the potential for the studies on the biotransformations of exogenous metal ions such as Cr(VI), in cultured cells. The results of multiple linear regression analyses of XANES spectra point to amino acid residues as the most likely donor groups for Cr(III) in Cr(VI)-treated mammalian cells.

Published
2007

83. A Multimodal Spectroscopic Imaging Method To Characterize the Metal and Macromolecular Content of Proteinaceous Aggregates (“Amyloid Plaques”)

Author

Summers, Kelly L., primary, Fimognari, Nicholas, additional, Hollings, Ashley, additional, Kiernan, Mitchell, additional, Lam, Virginie, additional, Tidy, Rebecca J., additional, Paterson, David, additional, Tobin, Mark J., additional, Takechi, Ryu, additional, George, Graham N., additional, Pickering, Ingrid J., additional, Mamo, John C., additional, Harris, Hugh H., additional, and Hackett, Mark J., additional

Published
2017
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84. Cellular Fates of Manganese(II) Pentaazamacrocyclic Superoxide Dismutase (SOD) Mimetics: Fluorescently Labeled MnSOD Mimetics, X-ray Absorption Spectroscopy, and X-ray Fluorescence Microscopy Studies

Author

Weekley, Claire M., primary, Kenkel, Isabell, additional, Lippert, Rainer, additional, Wei, Shengwei, additional, Lieb, Dominik, additional, Cranwell, Tiffanny, additional, Wedding, Jason L., additional, Zillmann, Annika S., additional, Rohr, Robin, additional, Filipovic, Milos R., additional, Ivanović-Burmazović, Ivana, additional, and Harris, Hugh H., additional

Published
2017
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86. Multi-modal spectroscopic imaging with synchrotron light to study mechanisms of brain disease

Author

Summers, Kelly L., additional, Fimognari, Nicholas, additional, Hollings, Ashley, additional, Kiernan, Mitchell, additional, Lam, Virginie, additional, Tidy, Rebecca J., additional, Takechi, Ryu, additional, George, Graham N., additional, Pickering, Ingrid J., additional, Mamo, John C., additional, Harris, Hugh H., additional, and Hackett, Mark J., additional

Published
2017
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89. Confocal Volumetric μXRF and Fluorescence Computed μ-Tomography Reveals Arsenic Three-Dimensional Distribution within Intact Pteris vittataFronds

Author

van der Ent, Antony, de Jonge, Martin D., Spiers, Kathryn M., Brueckner, Dennis, Montargès-Pelletier, Emmanuelle, Echevarria, Guillaume, Wan, Xiao-Ming, Lei, Mei, Mak, Rachel, Lovett, James H., and Harris, Hugh H.

Abstract

The fern Pteris vittatahas been the subject of numerous studies because of its extreme arsenic hyperaccumulation characteristics. However, information on the arsenic chemical speciation and distribution across cell types within intact frozen-hydrated Pteris vittatafronds is necessary to better understand the arsenic biotransformation pathways in this unusual fern. While 2D X-ray absorption spectroscopy imaging studies show that different chemical forms of arsenic, As(III) and As(V), occur across the plant organs, depth-resolved information on arsenic distribution and chemical speciation in different cell types within tissues of Pteris vittatahave not been reported. By using a combination of planar and confocal μ-X-ray fluorescence imaging and fluorescence computed μ-tomography, we reveal, in this study, the localization of arsenic in the endodermis and pericycle surrounding the vascular bundles in the rachis and the pinnules of the fern. Arsenic is also accumulated in the vascular bundles connecting into each sporangium, and in some mature sori. The use of 2D X-ray absorption near edge structure imaging allows for deciphering arsenic speciation across the tissues, revealing arsenate in the vascular bundles and arsenite in the endodermis and pericycle. This study demonstrates how different advanced synchrotron X-ray microscopy techniques can be complementary in revealing, at tissue and cellular levels, elemental distribution and chemical speciation in hyperaccumulator plants.

Published
2020
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90. Mechanisms of Uptake and Translocation of Thallium in BrassicaVegetables: An X-ray Fluorescence Microspectroscopic Investigation

Author

Corzo-Remigio, Amelia, Harris, Hugh H., Kidman, Clinton J., Nkrumah, Philip Nti, Casey, Lachlan W., Paterson, David J., Edraki, Mansour, and van der Ent, Antony

Abstract

Most nonoccupational human exposure to thallium (Tl) occurs via consumption of contaminated food crops. Brassicacultivars are common crops that can accumulate more than 500 μg Tl g–1. Knowledge of Tl uptake and translocation mechanisms in Brassicacultivars is fundamental to developing methods to inhibit Tl uptake or conversely for potential use in phytoremediation of polluted soils. Brassicacultivars (25 in total) were subjected to Tl dosing to screen for Tl accumulation. Seven high Tl-accumulating varieties were selected for follow-up Tl dosing experiments. The highest Tl accumulating Brassicacultivars were analyzed by synchrotron-based micro-X-ray fluorescence to investigate the Tl distribution and synchrotron-based X-ray absorption near-edge structure spectroscopy (XANES) to unravel Tl chemical speciation. The cultivars exhibited different Tl tolerance and accumulation patterns with some reaching up to 8300 μg Tl g–1. The translocation factors for all the cultivars were >1 with Brassica oleraceavar. acephala(kale) having the highest translocation factor of 167. In this cultivar, Tl is preferentially localized in the venules toward the apex and along the foliar margins and in minute hot spots in the leaf blade. This study revealed through scanning electron microscopy and X-ray fluorescence analysis that highly Tl-enriched crystals occur in the stoma openings of the leaves. The finding is further validated by XANES spectra that show that Tl(I) dominates in the aqueous as well as in the solid form. The high accumulation of Tl in these Brassicacrops has important implications for food safety and results of this study help to understand the mechanisms of Tl uptake and translocation in these crops.

Published
2024
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94. Measurement of labile arsenic speciation in water and soil using diffusive gradients in thin films (DGT) and X-ray absorption near edge spectroscopy (XANES)

Author

Huynh, Trang, Harris, Hugh H., Zhang, Hao, Noller, Barry N., Huynh, Trang, Harris, Hugh H., Zhang, Hao, and Noller, Barry N.

Abstract

Arsenic speciation was determined in the solution extracted from a ferrihydrite binding gel layer in a DGT unit (FB-DGT) deployed in water using coupled high-performance liquid chromatography and hydride generation atomic fluorescence spectrometry (HPLC-HG-AFS). However, the extent of change in arsenic speciation during the extraction process is unknown. By identifying the arsenic species in the FB-DGT gel directly, using X-ray absorption near edge spectroscopy (XANES) fitting with model arsenic compounds, we obtain a better understanding of the ability of FB-DGT to measure labile arsenic species in solution. The results presented herein confirm that FB-DGT accumulated labile inorganic and methylated arsenic species. Arsenic species bound to the FB-DGT gel were stable for up to 2 weeks following deployment. However, caution should be applied when interpreting the proportion of As species measured by HPLC-HG-AFS in solution extracted from FB-DGT because the distribution of arsenic species in extracted solutions was found to be modified by the extraction process. Some (~20 %) of arsenate was converted into arsenite, and a significant amount (~25 %) of dimethylarsinic acid (DMAsV) was converted into monomethylarsonic acid (MMAsV) or arsenate (AsV). Only inorganic arsenite (iAsIII) was stable during the extraction process. These findings suggested that, based on the XANES measurement, although As species were quantitatively accumulated in the FB-DGT gel, the FB-DGT technique was still unsuitable for studying As speciation. This is because changes in arsenic speciation were observed to occur during gel extraction, prior to HPLC-HG-AFS measurement, and because the XANES technique is available for routine measurements.

Published
2015

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