title: Fast x-ray fluorescence microtomography of hydrated biological samples.
abstract: Metals and metalloids play a key role in plant and other biological systems as some of them are essential to living organisms and all can be toxic at high concentrations. It is therefore important to understand how they are accumulated, complexed and transported within plants. In situ imaging of metal distribution at physiological relevant concentrations in highly hydrated biological systems is technically challenging. In the case of roots, this is mainly due to the possibility of artifacts arising during sample preparation such as cross sectioning. Synchrotron x-ray fluorescence microtomography has been used to obtain virtual cross sections of elemental distributions. However, traditionally this technique requires long data acquisition times. This has prohibited its application to highly hydrated biological samples which suffer both radiation damage and dehydration during extended analysis. However, recent advances in fast detectors coupled with powerful data acquisition approaches and suitable sample preparation methods can circumvent this problem. We demonstrate the heightened potential of this technique by imaging the distribution of nickel and zinc in hydrated plant roots. Although 3D tomography was still impeded by radiation damage, we successfully collected 2D tomograms of hydrated plant roots exposed to environmentally relevant metal concentrations for short periods of time. To our knowledge, this is the first published example of the possibilities offered by a new generation of fast fluorescence detectors to investigate metal and metalloid distribution in radiation-sensitive, biological samples.
authors.affiliation: Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes, South Australia, Australia. enzo.lombi@unisa.edu.au
authors.forename: Enzo
authors.initials: E
authors.lastname: Lombi
authors.forename: Martin D
authors.initials: MD
authors.lastname: de Jonge
authors.forename: Erica
authors.initials: E
authors.lastname: Donner
authors.forename: Peter M
authors.initials: PM
authors.lastname: Kopittke
authors.forename: Daryl L
authors.initials: DL
authors.lastname: Howard
authors.forename: Robin
authors.initials: R
authors.lastname: Kirkham
authors.forename: Chris G
authors.initials: CG
authors.lastname: Ryan
authors.forename: David
authors.initials: D
authors.lastname: Paterson
mesh_terms: D007887:Fabaceae / Q000378:metabolism*; D009532:Nickel / Q000378:metabolism*; D018517:Plant Roots / Q000378:metabolism; D013050:Spectrometry, Fluorescence; D013997:Time Factors; D055114:X-Ray Microtomography / Q000379:methods*; D015032:Zinc / Q000378:metabolism*
chemical_list: D009532:Nickel; D015032:Zinc