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

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

Nuclear Microprobe Mapping of Statoliths of Chokka Squid Loligo vulgaris reynaudii d\u27Orbigny, 1845

Volume: 193Start Page: 125End Page: 14

Quantitative micro-PIXE mapping of squid statoliths

Distribution of elements in statoliths of squid Loligo vulgaris reynaudii d'Orbigny, 1845 was studied, using the true elemental imaging system (Dynamic Analysis) of the NAC nuclear microprobe. The analysis revealed various patterns of Ca and Sr distributions. The biological interpretation of the most frequent pattern is linked with the role of Sr in the statolith deposition process. Other patterns are linked with the technique used and the specific characteristics of the sample. Traces of other elements (Cr, Mn, Fe, Cu, Zn, Br, Pb) were also found. Likewise, their presence may have the biological interpretation (Zn, Cu and Br), or is an artefact linked to the methods and conditions of sample preparation and/or analysis. Methodical aspects of using proton backscattering for PIXE X-ray yield corrections are also discussed

Micro-PIXE investigation of bean seeds to assist micronutrient biofortification

This study compares the distribution and concentrations of micro- and macronutrients in different bean cultivars with the aim of optimizing the biofortification, a sustainable approach towards improving dietary quality. Micro-PIXE was used to reveal the distribution of Fe, Zn, Mn, Ca, P, S in seeds of common beans (Phaseolus vulgaris) and runner beans (Phaseolus coccineus). Average concentrations of elements in different tissues were obtained using ICP-AES. The highest concentrations of Zn in the studied beans were found in the embryonic axis, but an increased concentration of this element was also detected in the provascular bundles of the cotyledons. The first layer of cells surrounding provascular bundles accumulated high concentrations of Fe, while the next cell layer had an increased concentration of Mn. The analysis showed that the provascular bundles and the first cell layers surrounding them could have a significant role in the storage of important seed micronutrients Zn, Fe, and Mn. This information has important implications for molecular biology studies aimed at seed biofortification