TY - JOUR
T1 - Physiological response to a metal-contaminated invertebrate diet in zebrafish: Importance of metal speciation and regulation of metal transport pathways
AU - Boyle, David
AU - Hogstrand, Christer
AU - Bury, Nicolas R.
PY - 2011/9
Y1 - 2011/9
N2 - Dietary metal uptake in fish is determined by metal bioavailability in prey and the metal requirements of the fish. In this study zebrafish were fed the intertidal polychaete worm Nereis diversicolor (3% wet weight day(-1)) collected from Ag, Cd and Cu-impacted Restronguet Creek (RC) or a reference site, Blackwater estuary (BW), for 21 days. On days 0, 7, 14 and 21 fish were fed a single meal of RC or BW N. diversicolor labeled with Ag-110m or Cd-109 for measurements of metal assimilation efficiency (AE). Zebrafish intestines were also taken for mRNA expression analysis of copper transporter 1 (ctr1), divalent metal transporter 1 (dmt1) and metallothionein 2 (mt2). No significant difference was observed in the AE of Cd-109 in metal naive fish at day 0 between RC and BW worms, 11.8 +/- 2.1 and 15.3 +/- 2.8%, respectively. However, AE of Ag-110m was significantly greater in fish fed worms from BW compared to RC, 5 +/- 1.2% and 1.6 +/- 0.5%, respectively at day 0. Fractionation analysis of radiolabeled metal partitioned in N. diversicolor from RC revealed a greater proportion of Ag (40 +/- 1.1%) in a fraction containing protein and organelle bound metal, associated with high trophic availability, compared to BW polychaetes (24 +/- 2.5%). Lower AE of Ag-110m from RC polychaetes is therefore unlikely due to speciation of Ag-110m in N. diversicolor from RC, but to the high concentration of Cu, a potential Ag antagonist. Exposure to RC polychaetes significantly increased the AE of Ag-110m (6.2 +/- 1%), but not Cd-109, from RC worms, after 21 days. AE of Ag-110m and Cd-109 was unaffected by pre-exposure to BW. Elevated concentration of intestinal Cu and increased expression of ctr1. dmt1 and mt2 after 14 days exposure in fish fed worms from RC suggest altered Cu handling strategy of these fish which may increase AE of Ag via shared Ag and Cu transport pathways. These data suggest metal exposure history of invertebrates may affect metal bioavailability to fish, and fish may alter intestinal uptake physiology during chronic dietary exposure with implications for the assimilation and toxicity of dietary metals. (C) 2011 Elsevier B.V. All rights reserved.
AB - Dietary metal uptake in fish is determined by metal bioavailability in prey and the metal requirements of the fish. In this study zebrafish were fed the intertidal polychaete worm Nereis diversicolor (3% wet weight day(-1)) collected from Ag, Cd and Cu-impacted Restronguet Creek (RC) or a reference site, Blackwater estuary (BW), for 21 days. On days 0, 7, 14 and 21 fish were fed a single meal of RC or BW N. diversicolor labeled with Ag-110m or Cd-109 for measurements of metal assimilation efficiency (AE). Zebrafish intestines were also taken for mRNA expression analysis of copper transporter 1 (ctr1), divalent metal transporter 1 (dmt1) and metallothionein 2 (mt2). No significant difference was observed in the AE of Cd-109 in metal naive fish at day 0 between RC and BW worms, 11.8 +/- 2.1 and 15.3 +/- 2.8%, respectively. However, AE of Ag-110m was significantly greater in fish fed worms from BW compared to RC, 5 +/- 1.2% and 1.6 +/- 0.5%, respectively at day 0. Fractionation analysis of radiolabeled metal partitioned in N. diversicolor from RC revealed a greater proportion of Ag (40 +/- 1.1%) in a fraction containing protein and organelle bound metal, associated with high trophic availability, compared to BW polychaetes (24 +/- 2.5%). Lower AE of Ag-110m from RC polychaetes is therefore unlikely due to speciation of Ag-110m in N. diversicolor from RC, but to the high concentration of Cu, a potential Ag antagonist. Exposure to RC polychaetes significantly increased the AE of Ag-110m (6.2 +/- 1%), but not Cd-109, from RC worms, after 21 days. AE of Ag-110m and Cd-109 was unaffected by pre-exposure to BW. Elevated concentration of intestinal Cu and increased expression of ctr1. dmt1 and mt2 after 14 days exposure in fish fed worms from RC suggest altered Cu handling strategy of these fish which may increase AE of Ag via shared Ag and Cu transport pathways. These data suggest metal exposure history of invertebrates may affect metal bioavailability to fish, and fish may alter intestinal uptake physiology during chronic dietary exposure with implications for the assimilation and toxicity of dietary metals. (C) 2011 Elsevier B.V. All rights reserved.
U2 - 10.1016/j.aquatox.2011.05.003
DO - 10.1016/j.aquatox.2011.05.003
M3 - Article
VL - 105
SP - 21
EP - 28
JO - AQUATIC TOXICOLOGY
JF - AQUATIC TOXICOLOGY
IS - 1-2
ER -