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Arsenic As

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Andrew A. Meharg – One of the best experts on this subject based on the ideXlab platform.

  • Arsenic As a food chain contaminant mechanisms of plant uptake and metabolism and mitigation strategies
    Annual Review of Plant Biology, 2010
    Co-Authors: Fangjie Zhao, S P Mcgrath, Andrew A. Meharg

    Abstract:

    Arsenic (As) is an environmental and food chain contaminant. Excessive accumulation of As, particularly inorganic Arsenic (Asi), in rice (Oryza sativa) poses a potential health risk to populations with high rice consumption. Rice is efficient at As accumulation owing to flooded paddy cultivation that leads to arsenite mobilization, and the inadvertent yet efficient uptake of arsenite through the silicon transport pathway. Iron, phosphorus, sulfur, and silicon interact strongly with As during its route from soil to plants. Plants take up arsenate through the phosphate transporters, and arsenite and undissociated methylated As species through the nodulin 26-like intrinsic (NIP) aquaporin channels. Arsenate is readily reduced to arsenite in planta, which is detoxified by complexation with thiol-rich peptides such As phytochelatins and/or vacuolar sequestration. A range of mitigation methods, from agronomic meAsures and plant breeding to genetic modification, may be employed to reduce As uptake by food crops.

  • survey of Arsenic and its speciation in rice products such As breakfAst cereals rice crackers and japanese rice condiments
    Environment International, 2009
    Co-Authors: Paul N. Williams, Claire Deacon, Andrea Raab, Annemarie Carey, Jorg Feldmann, Andrew A. Meharg

    Abstract:

    Rice hAs been demonstrated to be one of the major contributors to Arsenic (As) in human diets in addition to drinking water, but little is known about rice products As an additional source of As exposure. Rice products were analyzed for total As and a subset of samples were meAsured for Arsenic speciation using high performance liquid chromatography interfaced with inductively coupled plAsma-mAss spectrometry (HPLC–ICP-MS). A wide range of rice products had total and inorganic Arsenic levels that typified those found in rice grain including, crisped rice, puffed rice, rice crackers, rice noodles and a range of Japanese rice condiments As well As rice products targeted at the macrobiotic, vegan, lactose intolerant and gluten intolerance food market. Most As in rice products are inorganic As (75.2–90.1%). This study provides a wider appreciation of how inorganic Arsenic derived from rice products enters the human diet.

  • Survey of Arsenic and its speciation in rice products such As breakfAst cereals, rice crackers and Japanese rice condiments
    Environment International, 2009
    Co-Authors: Guo Xin Sun, Paul N. Williams, Yong-guan Zhu, Claire Deacon, A. M. Carey, Andrea Raab, Joerg Feldmann, Andrew A. Meharg

    Abstract:

    Rice hAs been demonstrated to be one of the major contributors to Arsenic (As) in human diets in addition to drinking water, but little is known about rice products As an additional source of As exposure. Rice products were analyzed for total As and a subset of samples were meAsured for Arsenic speciation using high performance liquid chromatography interfaced with inductively coupled plAsma-mAss spectrometry (HPLC-ICP-MS). A wide range of rice products had total and inorganic Arsenic levels that typified those found in rice grain including, crisped rice, puffed rice, rice crackers, rice noodles and a range of Japanese rice condiments As well As rice products targeted at the macrobiotic, vegan, lactose intolerant and gluten intolerance food market. Most As in rice products are inorganic As (75.2-90.1%). This study provides a wider appreciation of how inorganic Arsenic derived from rice products enters the human diet. © 2008 Elsevier Ltd. All rights reserved.

Paul N. Williams – One of the best experts on this subject based on the ideXlab platform.

  • survey of Arsenic and its speciation in rice products such As breakfAst cereals rice crackers and japanese rice condiments
    Environment International, 2009
    Co-Authors: Paul N. Williams, Claire Deacon, Andrea Raab, Annemarie Carey, Jorg Feldmann, Andrew A. Meharg

    Abstract:

    Rice hAs been demonstrated to be one of the major contributors to Arsenic (As) in human diets in addition to drinking water, but little is known about rice products As an additional source of As exposure. Rice products were analyzed for total As and a subset of samples were meAsured for Arsenic speciation using high performance liquid chromatography interfaced with inductively coupled plAsma-mAss spectrometry (HPLC–ICP-MS). A wide range of rice products had total and inorganic Arsenic levels that typified those found in rice grain including, crisped rice, puffed rice, rice crackers, rice noodles and a range of Japanese rice condiments As well As rice products targeted at the macrobiotic, vegan, lactose intolerant and gluten intolerance food market. Most As in rice products are inorganic As (75.2–90.1%). This study provides a wider appreciation of how inorganic Arsenic derived from rice products enters the human diet.

  • Survey of Arsenic and its speciation in rice products such As breakfAst cereals, rice crackers and Japanese rice condiments
    Environment International, 2009
    Co-Authors: Guo Xin Sun, Paul N. Williams, Yong-guan Zhu, Claire Deacon, A. M. Carey, Andrea Raab, Joerg Feldmann, Andrew A. Meharg

    Abstract:

    Rice hAs been demonstrated to be one of the major contributors to Arsenic (As) in human diets in addition to drinking water, but little is known about rice products As an additional source of As exposure. Rice products were analyzed for total As and a subset of samples were meAsured for Arsenic speciation using high performance liquid chromatography interfaced with inductively coupled plAsma-mAss spectrometry (HPLC-ICP-MS). A wide range of rice products had total and inorganic Arsenic levels that typified those found in rice grain including, crisped rice, puffed rice, rice crackers, rice noodles and a range of Japanese rice condiments As well As rice products targeted at the macrobiotic, vegan, lactose intolerant and gluten intolerance food market. Most As in rice products are inorganic As (75.2-90.1%). This study provides a wider appreciation of how inorganic Arsenic derived from rice products enters the human diet. © 2008 Elsevier Ltd. All rights reserved.

  • Rice-arsenate interactions in hydroponics: A three-gene model for tolerance
    Journal of Experimental Botany, 2008
    Co-Authors: Gareth J. Norton, Meher Nigar, Paul N. Williams, Tapash Dasgupta, Andrew A. Meharg, Adam H. Price

    Abstract:

    In this study, the genetic mapping of the tolerance of root growth to 13.3 muM arsenate [As(V)] using the BalaxAzucena population is improved, and candidate genes for further study are identified. A remarkable three-gene model of tolerance is advanced, which appears to involve epistatic interaction between three major genes, two on chromosome 6 and one on chromosome 10. Any combination of two of these genes inherited from the tolerant parent leads to the plant having tolerance. Lists of potential positional candidate genes are presented. These are then refined using whole genome transcriptomics data and bioinformatics. Physiological evidence is also provided that genes related to phosphate transport are unlikely to be behind the genetic loci conferring tolerance. These results offer testable hypotheses for genes related to As(V) tolerance that might offer strategies for mitigating Arsenic (As) accumulation in consumed rice.

Ming Hung Wong – One of the best experts on this subject based on the ideXlab platform.

  • oxic and anoxic conditions affect Arsenic As accumulation and arsenite transporter expression in rice
    Chemosphere, 2017
    Co-Authors: Chuan Wu, Ming Hung Wong, Liu Huang, William Hartley

    Abstract:

    Arsenic (As) exposure from rice consumption hAs now become a global health issue. This study aimed to investigate the effects of rice rhizosphere oxic conditions on silicate transporter (responsible for arsenite transportation) expressions, and on As accumulation and speciation in four rice genotypes, including two hybrid genotypes (Xiangfengyou9, Shenyou9586) and two indica subspecies (Xiangwanxian17, Xiangwanxian12). Oxic and anoxic treatments have different effects on root length (p < 0.001) and weight (p < 0.05). Total As concentrations in roots were dramatically lower in oxic treatments (88.8–218 mg/kg), compared to anoxic treatments (147–243 mg/kg) (p < 0.001). Moreover, root and shoot arsenite concentrations in oxic treatments were lower than that in anoxic treatments in arsenite treatments. The relative abundance of silicate transporter expressions displayed a trend of down-regulation in oxic treatments compared to anoxic treatments, especially significantly different for Xiangwanxian17, Xiangwanxian12 in Lsi1 expressions (p < 0.05), Xiangfengyou9, Shenyou9586, Xiangwanxian17 in Lsi2 expressions (p < 0.05). However, there were no significant differences of transporter expressions in different As treatments and genotypes. It may be a possible reAson for low As accumulation in rice growing aerobically compared to flooded condition and a potential route to reduce the health risk of As in rice.

  • Arsenic speciation in total contents and bioaccessible fractions in atmospheric particles related to human intakes
    Environmental Pollution, 2014
    Co-Authors: Minjuan Huang, Xunwen Chen, Yinge Zhao, Chuen Yu Chan, Wei Wang, Xuemei Wang, Ming Hung Wong

    Abstract:

    Speciation of inorganic trivalent Arsenicals (iAsIII), inorganic pentavalent Arsenicals (iAsV), monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) in total Arsenic (As) content and its bioaccessible fractions contained in road dust, household air-conditioning (AC) filter dust and PM2.5wAs investigated. Inorganic As, especially iAsV, wAs observed As the dominant species. Physiologically bAsed extraction test (PBET), an in-vitro gAstrointestinal method, wAs used to estimate the oral As bioaccessibility in coarse particles and the species present in the oral bioaccessible fraction. A composite lung simulating serum wAs used to mimic the pulmonary condition to extract the respiratory bioaccessible As and its species in PM2.5. Reduction of iAsVto iAsIIIoccurred in both in-vitro gAstrointestinal and lung simulating extraction models. The inorganic As species wAs the exclusive species for absorption through ingestion and inhalation of atmospheric particles, which wAs an important exposure route to inorganic As, in addition to drinking water and food consumption. © 2014 Elsevier Ltd. All rights reserved.

  • organic acids in two Arsenic hyperaccumulators and a non hyperaccumulator of pteris exposed to elevated Arsenic concentrations
    International Journal of Environmental Analytical Chemistry, 2011
    Co-Authors: Hongbin Wang, Ming Hung Wong, Z. H. Ye

    Abstract:

    Six organic acids (oxalic, malonic, malic, citric, palmitic and linolenic acid) in two Arsenic (As) hyperaccumulators (Pteris multifida and Pteris vittata) and a non-hyperaccumulator fern (Pteris semipinnata) exposed to different As concentrations (0, 5, 20 and 40 mg As L−1) under hydroponic conditions were determined using gAs chromatography-mAss spectrometry (GC-MS). Three fern species were collected from an uncontaminated site, but two As-hyperaccumulators were also collected from an As-contaminated site. Furthermore, the time-course effect of organic acid production in P. multifida and P. semipinnata collected from the uncontaminated site were also studied under 0 and 20 mg As L–1 treatments with a sampling interval at 0, 6, 12, 24 and 36 h. After esterifying (H2SO4–CH3OH), extracting (CH2Cl2), wAshing (saturated NaCl) and drying (anhydrous Na2SO4), these organic acids were isolated (Column: HP Ultra 2, 50 m × 0.2 mM × 0.33 µM; Carrier gAs: He). There wAs no significant increAse in the concentrations …