title: In situ metal imaging and Zn ligand-speciation in a soil-dwelling sentinel: complementary electron microprobe and synchrotron microbeam X-ray analyses.
abstract: Understanding the relationships between accumulated metal speciation in cells and tissues of ecologically significant taxa such as earthworms will improve risk assessments. Synchrotron-based μ-focus X-ray spectroscopy was used to detect, localize, and determine ligand-speciation of Zn and Pb in thin sections of two epigeic earthworm species collected from a Pb/Zn-mine soil. The findings indicated that Zn and Pb partition predominantly as typical hard acids (i.e., strong affinities for O-donors) within liverlike chloragocytes. Moreover, Zn speciation was very similar in the chloragog and intestinal epithelia but differed subtly in the kidneylike nephridial tubules; neither Zn nor Pb was detectable in the ventral nerve cord. High resolution X-ray mapping of high pressure-frozen, ultrathin, freeze-substituted sections in a transmission electron microscope (TEM), combined with conventional TEM structural analysis, identified a new cell type packed with highly organized rough endoplasmic reticulum and containing deposits of Cd (codistributed with S); there was no evidence that these cells are major depositories of Zn or Pb. These data may be used in a systems biology approach to assist in the interpretation of metal-evoked perturbations in whole-worm transcriptome and metabolome profiles.
authors.affiliation: Cardiff School of Biosciences, Cardiff University, Park Place, Cardiff CF10 3US, Wales, UK. morganaj1@cardiff.ac.uk
authors.forename: A J
authors.initials: AJ
authors.lastname: Morgan
authors.forename: J F W
authors.initials: JF
authors.lastname: Mosselmans
authors.forename: J M
authors.initials: JM
authors.lastname: Charnock
authors.forename: A
authors.initials: A
authors.lastname: Bennett
authors.forename: C
authors.initials: C
authors.lastname: Winters
authors.forename: M
authors.initials: M
authors.lastname: O'Reilly
authors.forename: P
authors.initials: P
authors.lastname: Fisher
authors.forename: J
authors.initials: J
authors.lastname: Andre
authors.forename: M
authors.initials: M
authors.lastname: Turner
authors.forename: P
authors.initials: P
authors.lastname: Gunning
authors.forename: P
authors.initials: P
authors.lastname: Kille
mesh_terms: D000818:Animals; D002104:Cadmium / Q000032:analysis* / Q000378:metabolism; D004577:Electron Probe Microanalysis; D004784:Environmental Monitoring; D007854:Lead / Q000032:analysis* / Q000378:metabolism; D009835:Oligochaeta / Q000378:metabolism* / Q000648:ultrastructure*; D012987:Soil / Q000032:analysis; D012989:Soil Pollutants / Q000032:analysis* / Q000378:metabolism; D017356:Synchrotrons; D056928:X-Ray Absorption Spectroscopy; D014965:X-Rays; D015032:Zinc / Q000032:analysis* / Q000378:metabolism
chemical_list: D012987:Soil; D012989:Soil Pollutants; D002104:Cadmium; D007854:Lead; D015032:Zinc