Overexpression of METAL TOLERANCE PROTEIN8 reveals new aspects of metal transport in Arabidopsis thaliana seeds.

METAL TOLERANCE PROTEIN8 (MTP8) of Arabidopsis thaliana is a member of the CATION DIFFUSION FACILITATOR (CDF) family of proteins that transports primarily manganese (Mn), but also iron (Fe). MTP8 mediates Mn allocation to specific cell types in the developing embryo, and Fe re-allocation as well as Mn tolerance during imbibition. We analysed if an overexpression of MTP8 driven by the CaMV 35S promoter has an effect on Mn tolerance during imbibition and on Mn and Fe storage in seeds, which would render it a biofortification target. Fe, Mn and Zn concentrations in MTP8-overexpressing lines in wild type and vit1-1 backgrounds were analysed by ICP-MS. Distribution of metals in intact seeds was determined by synchrotron µXRF tomography. MTP8 overexpression led to a strongly increased Mn tolerance of seeds during imbibition, supporting its effectiveness in loading excess Mn into the vacuole. In mature seeds, MTP8 overexpression did not cause a consistent increase in Mn and Fe accumulation, and it did not change the allocation pattern of these metals. Zn concentrations were consistently increased in bulk samples. The results demonstrate that Mn and Fe allocation is not determined primarily by the MTP8 expression pattern, suggesting either a cell type-specific provision of metals for vacuolar sequestration by upstream transport processes, or the determination of MTP8 activity by post-translational regulation.

Visualising coordination chemistry: fluorescence X-ray absorption near edge structure tomography.

Coordination chemistry underlies the structure/function of biological metal complexes. Contextualising this chemical information within an organism's physiology is critical for enhancing the understanding of bioinorganic chemistry but few high-fidelity probes are available. Here we develop fluorescence X-ray absorption near-edge structure tomography as a means for studying the spatial arrangement of biological coordination chemistry within intact organisms, and demonstrate the approach by mapping the distribution of cuprous and cupric complexes within Drosophila melanogaster.

The effect of vacancy ordering on quadrupole shifts in Mössbauer spectra of maghemite.

Electric field gradient (EFG) lattice sums for the vacancy-disordered and vacancy-ordered forms of maghemite were evaluated using a point charge model. The calculated EFGs produced a wide range of magnitudes and principal directions for the quadrupole interaction for both forms of maghemite. Small perturbations of the crystallographic parameters were shown to have a significant effect on the quadrupole shift. The effects observed were significant enough to show that quadrupole shifts should be considered when fitting the Mössbauer spectra of maghemite.

Research priorities for urological care following spinal cord injury: recommendations of an expert panel.

OBJECTIVE: A multidisciplinary panel of experts from Canada and the United States was convened by the Ontario Neurotrauma Foundation (ONF) to establish research priorities in the area of urological care following spinal cord injury (SCI). DESIGN: The panel reviewed a synthesis of published literature in five areas of urology, identified emerging opportunities in the private and public sector, and used a modified Delphi approach to reach consensus on priorities for funding. RESULTS: The panel recommendations included: clinical trials of the safety and efficacy of M3 receptor specific anti-muscarinic agents for bladder hyperactivity in SCI patients; development and testing of protocols for sacral nerve electrostimulation without sacral afferent neurectomy for management of micturition - including selective stimulation of sacral nerve fibers, high frequency blocking of the pudendal nerve to minimize the risk of urethral sphincter co-contraction and genital nerve stimulation for bladder inhibition and incontinence management; clinical trials of the efficacy and safety of intra-urethral valve catheters; trials of the efficacy of probiotics for bacterial interference i.e. to reduce colonization by uropathogens and manage the dual problems of infection and pathogen resistance to anti-microbials: innovations in the prevention or treatment of stone disease (ureteral, bladder and kidney). CONCLUSIONS: The recommendations form the strategic priorities of the ONF SCI grants program for Ontario-based investigators and their partnerships with out-of-province collaborators and organizations.