title: DNA damage in earthworms from highly contaminated soils: assessing resistance to arsenic toxicity by use of the Comet assay.
abstract: Earthworms native to the former mine site of Devon Great Consols (DGC), UK reside in soils highly contaminated with arsenic (As). These earthworms are considered to have developed a resistance to As toxicity. The mechanisms underlying this resistance however, remain unclear. In the present study, non-resistant, commercially sourced Lumbricus terrestris were exposed to a typical DGC soil in laboratory mesocosms. The earthworms bio-accumulated As from the soil and incurred DNA-damage levels significantly above those observed in the control mesocosm (assessed using the Comet assay). A dose response was observed between DNA damage (% tail DNA) and As concentration in soil (control, 98, 183, 236, 324 and 436mgkg(-1)). As-resistant earthworms (Lumbricus rubellus, Dendrodrilus rubidus and L. terrestris) collected from contaminated soils at DGC (203 to 9025mgkg(-1) As) had also bio-accumulated high levels of As from their host soils, yet demonstrated low levels of DNA damage compared with earthworms from uncontaminated sites. The results demonstrate that the As-contaminated soils at DGC are genotoxic to non-native earthworms and much less so to earthworms native to DGC, thus providing further evidence of an acquired resistance to As toxicity in the native earthworms.
authors.affiliation: British Geological Survey, Keyworth Nottingham, NG12 5GG UK. drmbutton@gmail.com
authors.forename: Mark
authors.initials: M
authors.lastname: Button
authors.forename: Gawen R T
authors.initials: GR
authors.lastname: Jenkin
authors.forename: Karen J
authors.initials: KJ
authors.lastname: Bowman
authors.forename: Chris F
authors.initials: CF
authors.lastname: Harrington
authors.forename: Tim S
authors.initials: TS
authors.lastname: Brewer
authors.forename: George D D
authors.initials: GD
authors.lastname: Jones
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Watts
mesh_terms: D000818:Animals; D001151:Arsenic / Q000633:toxicity*; D020552:Comet Assay; D004249:DNA Damage; D004305:Dose-Response Relationship, Drug; D008906:Mining; D009835:Oligochaeta / Q000235:genetics*; D012989:Soil Pollutants / Q000633:toxicity*
chemical_list: D012989:Soil Pollutants; D001151:Arsenic