title: Effects of methylmercury on epigenetic markers in three model species: mink, chicken and yellow perch.
abstract: We previously reported that methylmercury (MeHg) exposure is associated with DNA hypomethylation in the brain stem of male polar bears. Here, we conveniently use archived tissues obtained from controlled laboratory exposure studies to look for evidence that MeHg can disrupt DNA methylation across taxa. Brain (cerebrum) tissues from MeHg-exposed mink (Neovison vison), chicken (Gallus gallus) and yellow perch (Perca flavescens) were analyzed for total Hg levels and global DNA methylation. Tissues from chicken and mink, but not perch, were also analyzed for DNA methyltransferase (DNMT) activity. In mink we observed significant reductions in global DNA methylation in an environmentally-relevant dietary exposure group (1 ppm MeHg), but not in a higher group (2 ppm MeHg). DNMT activity was significantly reduced in all treatment groups. In chicken or yellow perch, no statistically significant effects of MeHg were observed. Dose-dependent trends were observed in the chicken data but the direction of the change was not consistent between the two endpoints. Our results suggest that MeHg can be epigenetically active in that it has the capacity to affect DNA methylation in mammals. The variability in results across species may suggest inter-taxa differences in epigenetic responses to MeHg, or may be related to differences among the exposure scenarios used as animals were exposed to MeHg through different routes (dietary, egg injection), for different periods of time (19-89 days) and at different life stages (embryonic, juvenile, adult).
authors.affiliation: Department of Environmental Health Sciences, University of Michigan, 1415 Washington Heights, Ann Arbor, MI 48109, USA. niladri@umich.edu
authors.forename: Niladri
authors.initials: N
authors.lastname: Basu
authors.forename: Jessica
authors.initials: J
authors.lastname: Head
authors.forename: Dong-Ha
authors.initials: DH
authors.lastname: Nam
authors.forename: J Richard
authors.initials: JR
authors.lastname: Pilsner
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Carvan
authors.forename: Hing Man
authors.initials: HM
authors.lastname: Chan
authors.forename: Frederick W
authors.initials: FW
authors.lastname: Goetz
authors.forename: Cheryl A
authors.initials: CA
authors.lastname: Murphy
authors.forename: Kirsti
authors.initials: K
authors.lastname: Rouvinen-Watt
authors.forename: Anton M
authors.initials: AM
authors.lastname: Scheuhammer
mesh_terms: D000818:Animals; D001921:Brain / Q000187:drug effects / Q000196:embryology; D002642:Chick Embryo; D002645:Chickens / Q000235:genetics*; D019175:DNA Methylation / Q000187:drug effects*; D015254:DNA Modification Methylases / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D054750:Ecotoxicology / Q000379:methods; D044127:Epigenesis, Genetic / Q000187:drug effects*; D006321:Heart / Q000187:drug effects; D008099:Liver / Q000187:drug effects; D008767:Methylmercury Compounds / Q000633:toxicity*; D008907:Mink / Q000235:genetics*; D010471:Perches / Q000235:genetics*; D013045:Species Specificity
chemical_list: D008767:Methylmercury Compounds; D015254:DNA Modification Methylases