Truter J.C., Wyk J.H.V., Oberholster P.J., Botha A.-M.
Department of Botany and Zoology, Stellenbosch University, Private Bag X1, Stellenbosch 7602, South Africa; CSIR Natural Resources and the Environment, P.O. Box 320, Stellenbosch 7599, South Africa; Department of Genetics, Stellenbosch University, Private Bag X1, Stellenbosch 7602, South Africa
Truter, J.C., Department of Botany and Zoology, Stellenbosch University, Private Bag X1, Stellenbosch 7602, South Africa; Wyk, J.H.V., Department of Botany and Zoology, Stellenbosch University, Private Bag X1, Stellenbosch 7602, South Africa; Oberholster, P.J., CSIR Natural Resources and the Environment, P.O. Box 320, Stellenbosch 7599, South Africa; Botha, A.-M., Department of Genetics, Stellenbosch University, Private Bag X1, Stellenbosch 7602, South Africa
Acid mine drainage (AMD) is a global environmental concern due to detrimental impacts on river ecosystems. Little is however known regarding the biological impacts of neutralized AMD on aquatic vertebrates despite excessive discharge into watercourses. The aim of this investigation was to evaluate the endocrine modulatory potential of neutralized AMD, using molecular biomarkers in the teleost fish Oreochromis mossambicus in exposure studies. Surface water was collected from six locations downstream of a high density sludge (HDS) AMD treatment plant and a reference site unimpacted by AMD. The concentrations of 28 elements, including 22 metals, were quantified in the exposure water in order to identify potential links to altered gene expression. Relatively high concentrations of manganese (~ 10. mg/l), nickel (~ 0.1. mg/l) and cobalt (~ 0.03. mg/l) were detected downstream of the HDS plant. The expression of thyroid receptor-α (trα), trβ, androgen receptor-1 (ar1), ar2, glucocorticoid receptor-1 (gr1), gr2, mineralocorticoid receptor (mr) and aromatase (cyp19a1b) was quantified in juvenile fish after 48. h exposure. Slight but significant changes were observed in the expression of gr1 and mr in fish exposed to water collected directly downstream of the HDS plant, consisting of approximately 95 percent neutralized AMD. The most pronounced alterations in gene expression (i.e. trα, trβ, gr1, gr2, ar1 and mr) was associated with water collected further downstream at a location with no other apparent contamination vectors apart from the neutralized AMD. The altered gene expression associated with the "downstream" locality coincided with higher concentrations of certain metals relative to the locality adjacent to the HDS plant which may indicate a causative link. The current study provides evidence of endocrine disruptive activity associated with neutralized AMD contamination in regard to alterations in the expression of key genes linked to the thyroid, interrenal and gonadal endocrine axes of a teleost fish species. © 2013 Elsevier Inc.
aromatase; biological marker; cobalt; endocrine disruptor; manganese; mineralocorticoid receptor; nickel; surface water; thyroid hormone receptor alpha; acid mine drainage; biomarker; cobalt; concentration (composition); endocrine disruptor; gene expression; juvenile; molecular analysis; perciform; river pollution; sludge; acid mine drainage; androgen receptor 1 gene; androgen receptor 2 gene; aromatase gene; article; concentration (parameters); controlled study; endocrine disease; environmental exposure; environmental impact; gene; gene expression; genetic association; glucocorticoid receptor 1 gene; glucocorticoid receptor 2 gene; in vivo study; juvenile animal; mineralocorticoid receptor gene; molecular biology; Mozambique; nonhuman; Oreochromis mossambicus; sludge; thyroid receptor alpha gene; waste water treatment plant; water contamination; Oreochromis mossambicus; Teleostei; Vertebrata; Endocrine disruption; Fish; Gene expression; Metal ions; Treated acid mine drainage; Acids; Animals; Endocrine System; Fish Proteins; Gene Expression Regulation; Mining; Rivers; Tilapia; Water Pollutants, Chemical