Browsing by Author "Baker, AJM"

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    Characterization of foliar manganese (Mn) in Mn (hyper)accumulators using x-ray absorption spectroscopy
    (Wiley-Blackwell, 2010-12-01) Fernando, DR; Mizuno, T; Woodrow, IE; Baker, AJM; Collins, RN
    Plant hyperaccumulation of the essential nutrient manganese (Mn) is a rare phenomenon most evident in the Western Pacific region, and differs from hyperaccumulation of other elements. Mn hyperaccumulators employ a variety of species-dependent spatial distribution patterns in sequestering excess foliar Mn, including primary sequestration in both nonphotosynthetic and photosynthetic tissues. This investigation employed synchrotron X-ray absorption spectroscopy (XAS) in a comparative study of Mn (hyper)accumulators, to elucidate in situ the chemical form(s) of foliar Mn in seven woody species from Australia, New Caledonia and Japan. Foliar Mn was found to predominate as Mn(II) in all samples, with strong evidence of the role of carboxylic acids, such as malate or citrate, as complexing ligands. Overall, the X-ray absorption near-edge spectroscopy (XANES) and extended X-ray absorption fine-structure spectroscopy (EXAFS) data appeared weighted against previous observations that oxalate binds excess Mn in Mn-(hyper)accumulating species. © 2010, Wiley-Blackwell.
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    Localisation of trace metals in metal-accumulating plants using μ-PIXE
    (Wiley-Blackwell, 2008-03) Siegele, R; Kachenko, AG; Bhatia, NP; Wang, YD; Ionescu, M; Singh, B; Baker, AJM; Cohen, DD
    Particle induced x-ray emission (PIXE) is a very sensitive technique that can quickly and reliably measure a wide range of elements simultaneously with high sensitivity. Using a focused microbeam, elemental distributions can be mapped with high spatial resolution. We demonstrate high-resolution mapping of metals in plant leaves at 5 mu m resolution and its application in detecting sites of metal accumulation in metal-accumulating plant tissues. The importance of biological sample preparation is discussed by direct comparison of freeze-substitution and freeze-drying techniques routinely used in biological sciences. The advantages and limitations of quantitative elemental imaging using these techniques are also discussed. © 2008, Wiley-Blackwell.