title: Oxidative stress in earthworms short- and long-term exposed to highly Hg-contaminated soils.
abstract: Exposure to mercury is often assessed by the measurement of molecular and biochemical antioxidant defences against an excessive production of reactive oxygen species. Here we examined some selected biomarkers of oxidative stress in the earthworm Lumbricus terrestris short- (2d) and long-term (44 d) exposed to Hg-contaminated soils (up to 1287 mg/kg dry wt). This level of Hg exposure did not cause earthworm mortality, however it yielded organisms to a situation of oxidative stress which was evidenced by the time-dependent responses of biomarkers. The reduced to oxidized glutathione ratio was a sensitive and early biomarker of Hg exposure, although the glutathione reductase activity back returned their normal physiological concentrations. Metallothioneins and total glutathione seemed to have a significant role in reducing Hg-induced oxidative stress when exposure to Hg prolonged up to 44 d. We combined biomarker responses into an integrate biomarker index which positively correlated with the Hg concentrations measured in the postmitochondrial fraction of the earthworm muscle, and with the available Hg fraction in soil. Current results suggest that glutathione redox cycle can be a complementary tool in the exposure and effect assessment of Hg-polluted soils.
authors.affiliation: Laboratory of Ecotoxicology, University of Castilla-La Mancha, Avda. Carlos III, 54071 Toledo, Spain.
authors.forename: Andrea
authors.initials: A
authors.lastname: Colacevich
authors.forename: María J
authors.initials: MJ
authors.lastname: Sierra
authors.forename: Francesca
authors.initials: F
authors.lastname: Borghini
authors.forename: Rocio
authors.initials: R
authors.lastname: Millán
authors.forename: Juan C
authors.initials: JC
authors.lastname: Sanchez-Hernandez
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism; D005980:Glutathione Reductase / Q000378:metabolism; D008628:Mercury / Q000633:toxicity*; D009835:Oligochaeta / Q000378:metabolism*; D018384:Oxidative Stress / Q000187:drug effects*; D012989:Soil Pollutants / Q000633:toxicity*
chemical_list: D015415:Biomarkers; D012989:Soil Pollutants; D005980:Glutathione Reductase; D008628:Mercury; D005978:Glutathione