title: Protective effects of selenium on mercury-induced DNA damage in mussel haemocytes.
abstract: Little is known of the antioxidant role of selenium (Se) in aquatic invertebrates. We investigated the effects of Se on mercury-induced DNA damage in haemocytes from Mytilus edulis using alkaline single cell gel electrophoresis, that is, the Comet assay. The basal percentage tail DNA value for mussel haemocytes was 9.8+/-0.2% (mean+/-S.E.M., n=70). Exposing mussels to Hg(2+) (nominal concentration 20 microgL(-1)) for three days led to an increase in tail DNA to 61.1+/-1.8% (n=10). With added Se (as selenite, nominal concentration 4 microgL(-1)), Hg-induced DNA damage was reduced to 39.5+/-3.1% (n=10). Se pre-exposure also provided some protection against Hg-induced DNA damage (% tail DNA=51.0+/-2.9%, n=10). Basal glutathione peroxidase (GPx) activity in cell-free haemolymph was 93.7+/-3.5 nmol min(-1)mg(-1) (mean+/-S.E.M., n=70). Increases in GPx activity were seen when Se was added during and/or after exposure to Hg. For example, a 3-4-fold increase was seen after three days exposure to Hg in the presence of added Se. Interestingly GPx activity doubled after three days in the presence of added Se alone, but was unchanged after exposure to HgCl(2) alone. These results suggest that the availability of Se in the natural environment could affect the antioxidant status of mussels, and consequently could affect levels of DNA damage.
authors.affiliation: Ecotoxicology and Stress Biology Research Centre, School of Biological Sciences, University of Plymouth, Drake Circus, Plymouth, Devon, PL4 8AA, UK.
authors.forename: Damien
authors.initials: D
authors.lastname: Tran
authors.forename: A John
authors.initials: AJ
authors.lastname: Moody
authors.forename: Andrew S
authors.initials: AS
authors.lastname: Fisher
authors.forename: Michael E
authors.initials: ME
authors.lastname: Foulkes
authors.forename: Awadhesh N
authors.initials: AN
authors.lastname: Jha
mesh_terms: D000818:Animals; D020552:Comet Assay; D004249:DNA Damage / Q000187:drug effects*; D004347:Drug Interactions; D005979:Glutathione Peroxidase / Q000378:metabolism; D006434:Hemocytes / Q000187:drug effects / Q000201:enzymology; D008627:Mercuric Chloride / Q000633:toxicity*; D049880:Mytilus edulis / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics; D012623:Seawater; D018038:Sodium Selenite / Q000494:pharmacology*; D018709:Statistics, Nonparametric; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D014874:Water Pollutants, Chemical; D008627:Mercuric Chloride; D005979:Glutathione Peroxidase; D018038:Sodium Selenite