title: Could contaminant induced mutations lead to a genetic diversity overestimation?
abstract: Contaminant driven genetic erosion reported through the inspection of selectable traits can be underestimated using neutral markers. This divergence was previously reported in the aquatic system of an abandoned pyrite mine. The most sensitive genotypes of the microcrustacean cladoceran Daphnia longispina were found to be lacking in the impacted reservoir near the entrance of the metal rich acid mine drainage (AMD). Since that divergence could be, at least partially, accounted for by mutagenicity and genotoxicity of the AMD, the present study aimed at providing such a characterization. The Allium cepa chromosomal aberration assay, using root meristematic cells, was carried out, by exposing seeds to 100, 10, 1, and 0.1 % of the local AMD. Chromosomal aberrations, cell division phases and cell death were quantified after the AMD exposure and after 24 and 48 h recovery periods. The AMD revealed to be mutagenic and genotoxic, even after diluting it to 1 and 0.1 %. Dilutions within this range were previously found to be below the lethality threshold and to elicit sublethal effects on reproduction of locally collected D. longispina clonal lineages Significant mutagenic effects (micronuclei and chromosomal breaks) were also found at 0.1 % AMD, supporting that exposure may induce permanent genetic alterations. Recovery tests showed that AMD genotoxic effects persisted after the exposure.
authors.affiliation: Department of Life Sciences, IMAR-Instituto do Mar, University of Coimbra, Apartado 3046, 3001-401 Coimbra, Portugal.
authors.forename: Olímpia
authors.initials: O
authors.lastname: Sobral
authors.forename: Maria Aparecida
authors.initials: MA
authors.lastname: Marin-Morales
authors.forename: Rui
authors.initials: R
authors.lastname: Ribeiro
mesh_terms: D000818:Animals; D002869:Chromosome Aberrations / Q000139:chemically induced*; D019457:Chromosome Breakage; D004247:DNA / Q000187:drug effects; D003621:Daphnia / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D014644:Genetic Variation / Q000187:drug effects*; D007220:Industrial Waste / Q000009:adverse effects; D048629:Micronuclei, Chromosome-Defective / Q000139:chemically induced; D008906:Mining; D009153:Mutagens / Q000633:toxicity*; D009154:Mutation; D019697:Onions / Q000502:physiology; D018517:Plant Roots / Q000187:drug effects / Q000235:genetics; D015203:Reproducibility of Results; D014865:Waste Disposal, Fluid; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D007220:Industrial Waste; D009153:Mutagens; D014874:Water Pollutants, Chemical; D004247:DNA