Cu-Cd interactions in earthworms maintained in laboratory microcosms: the examination of a putative copper paradox.
Earthworms (Lumbricus rubellus) from Ecton (predominantly Cu-contaminated), Shipham (Cd-contaminated) and Dinas Powys (uncontaminated, reference) were maintained in the laboratory on soil from the sampling sites. Two principle exposure protocols were used: (1) a 4-week 'no pre-exposure experiment', where batches of earthworms were maintained on soils from each habitat and (2) a 'pre-exposure experiment' where uncontaminated control worms were maintained on Shipham soil for 4 weeks (the pre-exposure period), and then transferred to Ecton soil for a further 4 weeks, and vice versa. In summary, there were two primary findings. Firstly, exposure of worms to Cd-rich soil (Shipham) before exposure to Cu-rich soil (Ecton) increased the Cu burden and secondly, biochemical analysis of metal binding proteins in analogous earthworm populations indicated that Cu and Cd, but not Zn, are bound to a metallothionein homologue. These observations are consistent with the hypothesis that Cu does not induce thionein synthesis efficiently in earthworm tissues, but may bind avidly to Cd-induced thionein by substituting for Cd in the molecule because Cu-thionein is a more stable complex.
Mariño
F
F
School of Pure and Applied Biology, University of Wales Cardiff, UK.
Stürzenbaum
S R
SR
Kille
P
P
Morgan
A J
AJ
D000818:Animals; D001822:Body Burden; D002104:Cadmium / Q000032:analysis / Q000378:metabolism*; D003300:Copper / Q000032:analysis / Q000378:metabolism*; D004347:Drug Interactions; D008668:Metallothionein / Q000378:metabolism*; D009835:Oligochaeta / Q000378:metabolism*; D012987:Soil / Q000032:analysis; D012989:Soil Pollutants / Q000032:analysis / Q000378:metabolism*; D006113:United Kingdom
D012987:Soil; D012989:Soil Pollutants; D002104:Cadmium; D003300:Copper; D008668:Metallothionein