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Nehzati S, Dolgova NV, James AK, Cotelesage JJH, Sokaras D, Kroll T, George GN, Pickering IJ. High Energy Resolution Fluorescence Detected X-ray Absorption Spectroscopy: An Analytical Method for Selenium Speciation. Anal Chem 2021; 93:9235-9243. [PMID: 34164981 DOI: 10.1021/acs.analchem.1c01503] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Selenium is in many ways an enigmatic element. It is essential for health but toxic in excess, with the difference between the two doses being narrower than for any other element. Environmentally, selenium is of concern due to its toxicity. As the rarest of the essential elements, its low levels often provide challenges to the analytical chemist. X-ray absorption spectroscopy (XAS) provides a powerful tool for in situ chemical speciation but is severely limited by poor spectroscopic resolution arising from core-hole lifetime broadening. Here we explore selenium Kα1 high energy resolution fluorescence detected XAS (HERFD-XAS) as a novel approach for chemical speciation of selenium, in comparison with conventional Se K-edge XAS. We present spectra of a range of selenium species relevant to environmental and life science studies, including spectra of seleno-amino acids, which show strong similarities with S K-edge XAS of their sulfur congeners. We discuss strengths and limitations of HERFD-XAS, showing improvements in both speciation performance and low concentration detection. We also develop a simple method to correct fluorescence self-absorption artifacts, which is generally applicable to any HERFD-XAS experiment.
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Affiliation(s)
- Susan Nehzati
- Molecular and Environmental Sciences Group, Department of Geological Sciences, University of Saskatchewan, 114 Science Place, Saskatoon, Saskatchewan S7N 5E2, Canada
| | - Natalia V Dolgova
- Molecular and Environmental Sciences Group, Department of Geological Sciences, University of Saskatchewan, 114 Science Place, Saskatoon, Saskatchewan S7N 5E2, Canada
| | - Ashley K James
- Molecular and Environmental Sciences Group, Department of Geological Sciences, University of Saskatchewan, 114 Science Place, Saskatoon, Saskatchewan S7N 5E2, Canada.,Toxicology Centre, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5B3, Canada
| | - Julien J H Cotelesage
- Molecular and Environmental Sciences Group, Department of Geological Sciences, University of Saskatchewan, 114 Science Place, Saskatoon, Saskatchewan S7N 5E2, Canada
| | - Dimosthenis Sokaras
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, California 94025, United States
| | - Thomas Kroll
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, California 94025, United States
| | - Graham N George
- Molecular and Environmental Sciences Group, Department of Geological Sciences, University of Saskatchewan, 114 Science Place, Saskatoon, Saskatchewan S7N 5E2, Canada.,Toxicology Centre, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5B3, Canada.,Department of Chemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5C9, Canada
| | - Ingrid J Pickering
- Molecular and Environmental Sciences Group, Department of Geological Sciences, University of Saskatchewan, 114 Science Place, Saskatoon, Saskatchewan S7N 5E2, Canada.,Toxicology Centre, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5B3, Canada.,Department of Chemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5C9, Canada
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2
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Kaur G, Ponomarenko O, Zhou JR, Swanlund DP, Summers KL, Dolgova NV, Antipova O, Pickering IJ, George GN, Leslie EM. Studies of selenium and arsenic mutual protection in human HepG2 cells. Chem Biol Interact 2020; 327:109162. [PMID: 32524993 DOI: 10.1016/j.cbi.2020.109162] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Revised: 05/25/2020] [Accepted: 06/02/2020] [Indexed: 10/24/2022]
Abstract
Hundreds of millions of people worldwide are exposed to unacceptable levels of carcinogenic inorganic arsenic. Animal models have shown that selenium and arsenic are mutually protective through the formation and elimination of the seleno-bis(S-glutathionyl) arsinium ion [(GS)2AsSe]-. Consistent with this, human selenium deficiency in arsenic-endemic regions is associated with arsenic-induced disease, leading to the initiation of human selenium supplementation trials. In contrast to the protective effect observed in vivo, in vitro studies have suggested that selenite increases arsenite cellular retention and toxicity. This difference might be explained by the rapid conversion of selenite to selenide in vivo. In the current study, selenite did not protect the human hepatoma (HepG2) cell line against the toxicity of arsenite at equimolar concentrations, however selenide increased the IC50 by 2.3-fold. Cytotoxicity assays of arsenite + selenite and arsenite + selenide at different molar ratios revealed higher overall mutual antagonism of arsenite + selenide toxicity than arsenite + selenite. Despite this protective effect, in comparison to 75Se-selenite, HepG2 cells in suspension were at least 3-fold more efficient at accumulating selenium from reduced 75Se-selenide, and its accumulation was further increased by arsenite. X-ray fluorescence imaging of HepG2 cells also showed that arsenic accumulation, in the presence of selenide, was higher than in the presence of selenite. These results are consistent with a greater intracellular availability of selenide relative to selenite for protection against arsenite, and the formation and retention of a less toxic product, possibly [(GS)2AsSe]-.
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Affiliation(s)
- Gurnit Kaur
- Division of Analytical and Environmental Toxicology, Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Alberta, Canada; Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
| | - Olena Ponomarenko
- Department of Geological Sciences, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Janet R Zhou
- Division of Analytical and Environmental Toxicology, Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Alberta, Canada; Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
| | - Diane P Swanlund
- Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada; Department of Physiology, University of Alberta, Edmonton, Alberta, Canada
| | - Kelly L Summers
- Department of Geological Sciences, University of Saskatchewan, Saskatoon, Saskatchewan, Canada; Department of Chemistry, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Natalia V Dolgova
- Department of Geological Sciences, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Olga Antipova
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois, USA
| | - Ingrid J Pickering
- Department of Geological Sciences, University of Saskatchewan, Saskatoon, Saskatchewan, Canada; Department of Chemistry, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Graham N George
- Department of Geological Sciences, University of Saskatchewan, Saskatoon, Saskatchewan, Canada; Department of Chemistry, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Elaine M Leslie
- Division of Analytical and Environmental Toxicology, Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Alberta, Canada; Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada; Department of Physiology, University of Alberta, Edmonton, Alberta, Canada.
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3
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Dolgova NV, Nehzati S, MacDonald TC, Summers KL, Crawford AM, Krone PH, George GN, Pickering IJ. Disruption of selenium transport and function is a major contributor to mercury toxicity in zebrafish larvae. Metallomics 2020; 11:621-631. [PMID: 30688331 DOI: 10.1039/c8mt00315g] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Mercury is one of the most toxic elements threatening the biosphere, with levels steadily rising due to both natural and human activities. Selenium is an essential micronutrient, required for normal development and functioning of many organisms. While selenium is known to counteract mercury's toxicity under some conditions, to date information about the mercury-selenium relationship is fragmented and often controversial. As part of a systematic study of mercury and selenium interactions, zebrafish (Danio rerio) larvae (a model verterbrate) were exposed to methylmercury chloride or mercuric chloride. The influence of pre- and post-treatment of selenomethionine on the level and distribution of mercury and selenium in the brain and eye sections, as well as on toxicity, were examined. Selenomethionine treatment decreased the amount of maternally transfered mercury in the larval brain. Selenomethionine treatment prior to exposure to mercuric chloride increased both mercury and selenium levels in the brain but decreased their toxic effects. Conversely, methylmercury levels were not changed as a result of selenium pre-treatment, while toxicity was increased. Strikingly, both forms of mercury severely disrupted selenium metabolism, not only by depleting selenium levels due to formation of Hg-Se complexes, but also by blocking selenium transport into and out of tissues, suggesting that restoring normal selenium levels by treating the organism with selenium after mercury exposure may not be possible. Disruption of selenium metabolism by mercury may lead to disruption in function of selenoproteins. Indeed, the production of thyroid hormones by selenoprotein deiodinases was found to be severely impaired as a result of mercury exposure, with selenomethionine not always being a suitable source of selenium to restore thyroid hormone levels.
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Affiliation(s)
- Natalia V Dolgova
- Molecular and Environment Sciences Group, Department of Geological Sciences, University of Saskatchewan, 114 Science Place, Saskatoon, Saskatchewan S7N 5E2, Canada.
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4
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Yurkerwich K, Quinlivan PJ, Rong Y, Parkin G. Phenylselenolate Mercury Alkyl Compounds, PhSeHgMe and PhSeHgEt: Molecular Structures, Protolytic Hg-C Bond Cleavage and Phenylselenolate Exchange. Polyhedron 2016; 103:307-314. [PMID: 26644634 PMCID: PMC4669890 DOI: 10.1016/j.poly.2015.06.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The phenylselenolate mercury alkyl compounds, PhSeHgMe and PhSeHgEt, have been structurally characterized by X-ray diffraction, thereby demonstrating that both compounds are monomeric with approximately linear coordination geometries; the mercury centers do, nevertheless, exhibit secondary Hg•••Se intermolecular interactions that serve to increase the coordination number in the solid state. The ethyl derivative, PhSeHgEt, undergoes facile protolytic cleavage of the Hg-C bond to release ethane at room temperature, whereas PhSeHgMe exhibits little reactivity under similar conditions. Interestingly, the cleavage of the Hg-C bond of PhSeHgEt is also more facile than that of the thiolate analogue, PhSHgEt, which demonstrates that coordination by selenium promotes protolytic cleavage of the mercury-carbon bond. The phenylselenolate compounds PhSeHgR (R = Me, Et) also undergo degenerate exchange reactions with, for example, PhSHgR and RHgCl. In each case, the alkyl groups preserve coupling to the 199Hg nuclei, thereby indicating that the exchange process involves metathesis of the Hg-SePh/Hg-X groups rather than metathesis of the Hg-R/Hg-R groups.
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Affiliation(s)
- Kevin Yurkerwich
- Department of Chemistry, Columbia University, New York New York 10027,
USA
| | | | - Yi Rong
- Department of Chemistry, Columbia University, New York New York 10027,
USA
| | - Gerard Parkin
- Department of Chemistry, Columbia University, New York New York 10027,
USA
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Shehab H, Desouza ED, O’Meara J, Pejović-Milić A, Chettle DR, Fleming DEB, McNeill FE. Feasibility of measuring arsenic and selenium in human skin usingin vivox-ray fluorescence (XRF)—a comparison of methods. Physiol Meas 2015; 37:145-61. [DOI: 10.1088/0967-3334/37/1/145] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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6
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Palmer J, Parkin G. Protolytic cleavage of Hg-C bonds induced by 1-methyl-1,3-dihydro-2H-benzimidazole-2-selone: synthesis and structural characterization of mercury complexes. J Am Chem Soc 2015; 137:4503-16. [PMID: 25822075 PMCID: PMC4415037 DOI: 10.1021/jacs.5b00840] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2015] [Indexed: 12/22/2022]
Abstract
Multinuclear ((1)H, (77)Se, and (199)Hg) NMR spectroscopy demonstrates that 1-methyl-1,3-dihydro-2H-benzimidazole-2-selone, H(sebenzim(Me)), a structural analogue of the selenoamino acid, selenoneine, binds rapidly and reversibly to the mercury centers of HgX2 (X = Cl, Br, I), while X-ray diffraction studies provide evidence for the existence of adducts of composition [H(sebenzim(Me))]xHgX2 (X = Cl, x = 2, 3, 4; X = I, x = 2) in the solid state. H(sebenzim(Me)) also reacts with methylmercury halides, but the reaction is accompanied by elimination of methane resulting from protolytic cleavage of the Hg-C bond, an observation that is of relevance to the report that selenoneine demethylates CysHgMe, thereby providing a mechanism for mercury detoxification. Interestingly, the structures of [H(sebenzim(Me))]xHgX2 exhibit a variety of different hydrogen bonding patterns resulting from the ability of the N-H groups to form hydrogen bonds with chlorine, iodine, and selenium.
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Affiliation(s)
- Joshua
H. Palmer
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
| | - Gerard Parkin
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
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Galinha C, Sánchez-Martínez M, Pacheco AMG, Freitas MDC, Coutinho J, Maçãs B, Almeida AS, Pérez-Corona MT, Madrid Y, Wolterbeek HT. Characterization of selenium-enriched wheat by agronomic biofortification. Journal of Food Science and Technology 2014; 52:4236-45. [PMID: 26139888 DOI: 10.1007/s13197-014-1503-7] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 07/29/2014] [Indexed: 01/20/2023]
Abstract
Agronomic biofortification of staple crops is an effective way to enhance their contents in essential nutrients up the food chain, with a view to correcting for their deficiencies in animal or human status. Selenium (Se) is one such case, for its uneven distribution in the continental crust and, therefore, in agricultural lands easily translates into substantial variation in nutritional intakes. Cereals are far from being the main sources of Se on a content basis, but they are likely the major contributors to intake on a dietary basis. To assess their potential to assimilate and biotransform Se, bread and durum wheat were enriched with Se through foliar and soil addition at an equivalent field rate of 100 g of Se per hectare (ha), using sodium selenate and sodium selenite as Se-supplementation matrices, in actual field conditions throughout. Biotransformation of inorganic Se was evaluated by using HPLC-ICP-MS after enzymatic hydrolysis for Se-species extraction in the resulting mature wheat grains. Selenomethionine and Se(VI) were identified and quantified: the former was the predominant species, representing 70-100 % of the total Se in samples; the maximum amount of inorganic Se was below 5 %. These results were similar for both supplementation methods and for both wheat varieties. Judging from the present results, one can conclude that agronomic biofortification of wheat may improve the nutritional quality of wheat grains with significant amounts of selenomethionine, which is an attractive option for increasing the Se status in human diets through Se-enriched, wheat-based foodstuff.
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Affiliation(s)
- Catarina Galinha
- CERENA-IST, University of Lisbon, Av. Rovisco Pais 1, 1049-001 Lisboa, Portugal ; CCTN-IST, University of Lisbon, Estrada Nacional 10, 2695-066 Bobadela, Portugal ; Department of Radiation Science and Technology, Faculty of Applied Sciences, Delft University of Technology, Mekelweg 15, 2629 JB Delft, The Netherlands
| | - María Sánchez-Martínez
- Departamento de Química Analítica, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Avda. Complutense s/n, 28040 Madrid, Spain
| | - Adriano M G Pacheco
- CERENA-IST, University of Lisbon, Av. Rovisco Pais 1, 1049-001 Lisboa, Portugal
| | | | - José Coutinho
- INIAV, National Institute of Agricultural and Veterinary Research, Estrada de Gil Vaz, 7350-228 Elvas, Portugal
| | - Benvindo Maçãs
- INIAV, National Institute of Agricultural and Veterinary Research, Estrada de Gil Vaz, 7350-228 Elvas, Portugal
| | - Ana Sofia Almeida
- INIAV, National Institute of Agricultural and Veterinary Research, Estrada de Gil Vaz, 7350-228 Elvas, Portugal
| | - María Teresa Pérez-Corona
- Departamento de Química Analítica, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Avda. Complutense s/n, 28040 Madrid, Spain
| | - Yolanda Madrid
- Departamento de Química Analítica, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Avda. Complutense s/n, 28040 Madrid, Spain
| | - Hubert T Wolterbeek
- Department of Radiation Science and Technology, Faculty of Applied Sciences, Delft University of Technology, Mekelweg 15, 2629 JB Delft, The Netherlands
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8
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Palmer JH, Parkin G. 2-Seleno-1-alkylbenzimidazoles and their Diselenides: Synthesis and Structural Characterization of a 2-Seleno-1-methylbenzimidazole Complex of Mercury. Polyhedron 2013; 52:658-668. [PMID: 23543946 PMCID: PMC3610765 DOI: 10.1016/j.poly.2012.07.090] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
2-Seleno-1-methylbenzimidazole, H(sebenzimMe), can be synthesized from 1-methylbenzimidazole by sequential treatment with (i) BunLi, (ii) elemental selenium and (iii) HCl(aq). This method is also applicable to the synthesis of 2-seleno-1-t-butylbenzimidazole, H(sebenzimBut ). Single crystal X-ray diffraction and NMR spectroscopic data demonstrate that H(sebenzimMe) and H(sebenzimBut ) exist as the selone rather than the selenol tautomers, which is in accord with the results of density functional theory (B3LYP) calculations. The data also indicate that the selone is best represented as a C+-Se- zwitterion rather than as a C=Se doubly bonded species. Aerobic oxidation of H(sebenzimMe) and H(sebenzimBut ) in the presence of Et3N yields the diselenides, (sebenzimMe)2 and (sebenzimBut )2. In addition, H(sebenzimMe) reacts with HgCl2 to give [H(sebenzimMe)]2HgCl2, the first structurally characterized example of a 2-seleno-1-alkylimidazole mercury complex.
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Affiliation(s)
- Joshua H. Palmer
- Department of Chemistry, Columbia University, New York, New York 10027, USA
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9
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Yurkerwich K, Yurkerwich M, Parkin G. Synthesis and Structural Characterization of Tris(2-mercapto-1-adamantylimidazolyl)hydroborato Complexes: A Sterically Demanding Tripodal [S3] Donor Ligand. Inorg Chem 2011; 50:12284-95. [PMID: 21951277 DOI: 10.1021/ic201504d] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Kevin Yurkerwich
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Michael Yurkerwich
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Gerard Parkin
- Department of Chemistry, Columbia University, New York, New York 10027, United States
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10
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Selenium interactions and toxicity: a review. Cell Biol Toxicol 2011; 28:31-46. [DOI: 10.1007/s10565-011-9203-9] [Citation(s) in RCA: 180] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2011] [Accepted: 09/02/2011] [Indexed: 02/07/2023]
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Abstract
Bacillithiol (BSH), the α-anomeric glycoside of l-cysteinyl-d-glucosamine with l-malic acid, plays a dominant role in the cytosolic thiol redox chemistry of the low guanine and cytosine (GC) Gram-positive bacteria (phylum Firmicutes). BSH is functionally analogous to glutathione (GSH) but differs sufficiently in chemical structure that cells have evolved a distinct set of enzymes that use BSH as cofactor. BSH was discovered in Bacillus subtilis as a mixed disulfide with the redox-sensing repressor OhrR and in B. anthracis by biochemical analysis of pools of labeled thiols. The structure of BSH was determined after purification from Deinococcus radiodurans. Similarities in structure between BSH and mycothiol (MSH) facilitated the identification of biosynthetic genes for BSH in the model organism B. subtilis. Phylogenomic analyses have identified several candidate BSH-using or associated proteins, including a BSH reductase, glutaredoxin-like thiol-dependent oxidoreductases (bacilliredoxins), and a BSH-S-transferase (FosB) involved in resistance to the epoxide antibiotic fosfomycin. Preliminary results implicate BSH in cellular processes to maintain cytosolic redox balance and for adaptation to reactive oxygen, nitrogen, and electrophilic species. BSH also is predicted to chelate metals avidly, in part due to the appended malate moiety, although the implications of BSH for metal ion homeostasis have yet to be explored in detail.
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Affiliation(s)
- John D Helmann
- Department of Microbiology, Cornell University, Ithaca, New York 14853-8101, USA.
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12
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Melnick JG, Yurkerwich K, Parkin G. On the chalcogenophilicity of mercury: evidence for a strong Hg-Se bond in [Tm(Bu(t))]HgSePh and its relevance to the toxicity of mercury. J Am Chem Soc 2010; 132:647-55. [PMID: 20020759 PMCID: PMC2810633 DOI: 10.1021/ja907523x] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
One of the reasons for the toxic effects of mercury has been attributed to its influence on the biochemical roles of selenium. For this reason, it is important to understand details pertaining to the nature of Hg-Se interactions and this has been achieved by comparison of a series of mercury chalcogenolate complexes that are supported by tris(2-mercapto-1-t-butyl-imidazolyl)hydroborato ligation, namely [Tm(Bu(t))]HgEPh (E = S, Se, Te). In particular, X-ray diffraction studies on [Tm(Bu(t))]HgEPh demonstrate that although the Hg-S bonds involving the [Tm(Bu(t))] ligand are longer than the corresponding Cd-S bonds of [Tm(Bu(t))]CdEPh, the Hg-EPh bonds are actually shorter than the corresponding Cd-EPh bonds, an observation which indicates that the apparent covalent radii of the metals in these compounds are dependent on the nature of the bonds. Furthermore, the difference in Hg-EPh and Cd-EPh bond lengths is a function of the chalcogen and increases in the sequence S (0.010 A) < Se (0.035 A) < Te (0.057 A). This trend indicates that the chalcogenophilicity of mercury increases in the sequence S < Se < Te. Thus, while mercury is often described as being thiophilic, it is evident that it actually has a greater selenophilicity, a notion that is supported by the observation of facile selenolate transfer from zinc to mercury upon treatment of [Tm(Bu(t))]HgSCH(2)C(O)N(H)Ph with [Tm(Bu(t))]ZnSePh. The significant selenophilicity of mercury is in accord with the aforementioned proposal that one reason for the toxicity of mercury is associated with it reducing the bioavailability of selenium.
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Affiliation(s)
| | - Kevin Yurkerwich
- Department of Chemistry, Columbia University, New York, New York 10027, USA
| | - Gerard Parkin
- Department of Chemistry, Columbia University, New York, New York 10027, USA
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13
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Williams PN, Islam S, Islam R, Jahiruddin M, Adomako E, Soliaman ARM, Rahman GKMM, Lu Y, Deacon C, Zhu YG, Meharg AA. Arsenic limits trace mineral nutrition (selenium, zinc, and nickel) in Bangladesh rice grain. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2009; 43:8430-6. [PMID: 19924980 DOI: 10.1021/es901825t] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
A reconnaissance of 23 paddy fields, from three Bangladesh districts, encompassing a total of 230 soil and rice plant samples was conducted to identify the extent to which trace element characteristics in soils and irrigation waters are reflected by the harvested rice crop. Field sites were located on two soil physiographic units with distinctly different As soil baseline and groundwater concentrations. For arsenic (As), both straw and grain trends closely fitted patterns observed for the soils and water. Grain concentration characteristics for selenium (Se), zinc (Zn), and nickel (Ni), however, were markedly different. Regressions of shoot and grain As against grain Se, Zn, and Ni were highly significant (P < 0.001), exhibiting a pronounced decline in grain trace-nutrient quality with increasing As content. To validate this further, a pot experiment cultivar screening trial, involving commonly cultivated high yielding variety (HYV) rice grown alongside two U.S. rice varieties characterized as being As tolerant and susceptible, was conducted on an As-amended uniform soil. Findings from the trial confirmed that As perturbed grain metal(loid) balances, resulting in severe yield reductions in addition to constraining the levels of Se, Zn, and Ni in the grain.
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Affiliation(s)
- Paul N Williams
- Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China
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14
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Gherase MR, Vallee ME, Fleming DEB. Simultaneous detection of As and Se in polyester resin skin phantoms. Appl Radiat Isot 2009; 68:743-5. [PMID: 19819714 DOI: 10.1016/j.apradiso.2009.09.037] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
It is known that As and Se act as metabolic antagonists. Hence, an improvement in assessing As-related health risks can be achieved by simultaneous quantitative measurements of both As and Se levels in the human body. In this paper, the simultaneous detection of trace concentrations of As and Se in polyester resin skin phantoms was demonstrated. The experiments were performed with a commercial miniature X-ray tube and silicon PiN detector X-ray fluorescence (XRF) system. No significant overlap between the K(alpha) peaks of the two elements was observed. Minimum detection limits of (1.05+/-0.02) microg As g(-1) and (0.88+/-0.02) microg Se g(-1) were found.
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Affiliation(s)
- Mihai R Gherase
- Physics Department, Mount Allison University, Sackville, New Brunswick, Canada.
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15
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Lenz M, Lens PNL. The essential toxin: the changing perception of selenium in environmental sciences. THE SCIENCE OF THE TOTAL ENVIRONMENT 2009; 407:3620-33. [PMID: 18817944 DOI: 10.1016/j.scitotenv.2008.07.056] [Citation(s) in RCA: 200] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2008] [Revised: 07/17/2008] [Accepted: 07/30/2008] [Indexed: 05/12/2023]
Abstract
During the last decades, the perception of selenium has undergone substantial changes. While its toxic effects were recognized causing hair and hoof loss in animals during the 1930s, its essential role in microbial, animal and human metabolism has been recognized later, i.e. with the discovery of selenium deficiency causing "white muscle disease" in feedstock in the 1950s. Nowadays, the positive effect of systematic selenium supplementation is discussed in manifold topics such as cancer or diabetes prevention and avian influenza susceptibility. Treatment of selenium containing waste streams poses a notable challenge to environmental engineers, and to date no ultimate solution has been found for e.g. the selenium contamination in agricultural areas of the western USA. For the future, selenium contamination carries an imminent danger, if the increasing energy demand is covered by fossil fuel combustion, which will lead to major selenium emission and toxicity. This review presents current knowledge of selenium's role in environmental sciences and outlines potentially feasible treatment options targeting a variety of selenium contaminated waste streams.
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Affiliation(s)
- Markus Lenz
- Sub-Department of Environmental Technology, Wageningen University, Bomenweg 2, 6700 EV Wageningen, The Netherlands
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