Induction and metal speciation of metallothionein in wood mice (Apodemus sylvaticus) along a metal pollution gradient.
We investigated the binding of Cd, Cu, and Zn to metallothionein (MT) and other metal-binding proteins in free-living wood mice (Apodemus sylvaticus L.) captured in four areas along a metal pollution gradient. We measured total and cytosolic Cd, Cu, and Zn concentrations in mouse liver and kidney by means of inductively coupled plasma-mass spectrometry (ICP-MS). Total (Cu, Cd, Zn)-MT levels were determined in the same tissues by means of the cadmium thiomolybdate saturation assay. Metal speciation of metalloproteins was studied by means of size-exclusion high-performance liquid chromatography-ICP-MS. Liver and kidney of wood mice from the site adjacent to the pollution source showed the highest Cd and Zn concentrations (total and cytosolic) and (Cu, Cd, Zn)-MT levels compared to the other sites farther away from the pollution source. No or only small site differences in tissue Cu concentrations were observed. Almost all the variation (85-95%) in hepatic and renal (Cu, Cd, Zn)-MT levels was explained by the total or cytosolic hepatic Zn and Cd concentration or the renal Cd concentration, respectively. An analysis of the cytosolic metal speciation showed that the Cd-MT, Cu-MT, and Zn-MT fractions in liver and kidney increased significantly with increasing cytosolic metal concentrations. Metals associated with the other cytosolic protein fractions did not increase with increasing exposure. These results illustrate the important role of MT in metal homeostasis and detoxification processes. We conclude that MT is a useful biomarker for environmental metal contamination in free-living wood mice.
Rogival
Damien
D
Department of Biology, Ecophysiology, Biochemistry, and Toxicology Group, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium. damien.rogival@ua.ac.be
Van Campenhout
Karen
K
Infante
Heidi Goenaga
HG
Hearn
Ruth
R
Scheirs
Jan
J
Blust
Ronny
R
D000818:Animals; D002104:Cadmium / Q000032:analysis; D003300:Copper / Q000032:analysis; D003600:Cytosol / Q000737:chemistry; D004785:Environmental Pollutants / Q000032:analysis*; D007668:Kidney / Q000737:chemistry; D008099:Liver / Q000737:chemistry; D013058:Mass Spectrometry; D008668:Metallothionein / Q000032:analysis*; D008670:Metals / Q000032:analysis*; D051379:Mice; D015032:Zinc / Q000032:analysis
D004785:Environmental Pollutants; D008670:Metals; D002104:Cadmium; D003300:Copper; D008668:Metallothionein; D015032:Zinc