Cadmium detoxification in earthworms: from genes to cells.
Cadmium pollution has clear ecotoxicological consequences as it is readily bio-available and has a reported tendency to bio-accumulate in soil biota. Understanding the mechanisms of cadmium trafficking pathways within sentinel terrestrial invertebrates, such as the earthworm, is therefore considered to be of importance. Using X-ray microanalysis, quantitative polymerase chain reaction, and immunohistochemical techniques, we were able to demonstrate that the earthworm has the intrinsic capacity to efficiently sequester and compartmentalize cadmium via a metallothionein-mediated trafficking pathway. There is evidence that wMT-2, rather than wMT-1, is the major isoform implicated in the detoxification of cadmium and the identification of three independent wMT-2 loci (totalling over 25 kb of genomic sequence) has revealed a complex genomic organization. Complementary in silico analysis of over 6500 expressed sequence tags has identified a third metallothionein isoform, wMT-3, found to be highly enriched in embryonic tissue. In summary, this paper provides a detailed dissection of the genetic, molecular, and cellular basis of a sophisticated pathway that facilitates the uptake, accumulation, transport, and excretion of cadmium.
Stürzenbaum
Stephen R
SR
Cardiff University, School of Biosciences, Main Building, Cardiff, CF10 3TL UK. SturzenbaumSR@Cardiff.ac.uk
Georgiev
Oleg
O
Morgan
A John
AJ
Kille
Peter
P
D000595:Amino Acid Sequence; D000818:Animals; D002104:Cadmium / Q000378:metabolism* / Q000633:toxicity; D018076:DNA, Complementary / Q000378:metabolism; D004577:Electron Probe Microanalysis; D023281:Genomics; D007150:Immunohistochemistry; D008658:Inactivation, Metabolic; D008668:Metallothionein / Q000737:chemistry / Q000378:metabolism; D008969:Molecular Sequence Data; D009835:Oligochaeta / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D012989:Soil Pollutants / Q000378:metabolism* / Q000633:toxicity
D018076:DNA, Complementary; D012333:RNA, Messenger; D012989:Soil Pollutants; D002104:Cadmium; D008668:Metallothionein