title: Dietary iron alters waterborne copper-induced gene expression in soft water acclimated zebrafish (Danio rerio).
abstract: Metals like iron (Fe) and copper (Cu) function as integral components in many biological reactions, and, in excess, these essential metals are toxic, and organisms must control metal acquisition and excretion. We examined the effects of chronic waterborne Cu exposure and the interactive effects of elevated dietary Fe on gene expression and tissue metal accumulation in zebrafish. Softwater acclimated zebrafish exposed to 8 microg/l Cu, with and without supplementation of a diet high in Fe (560 vs. 140 mg Fe/kg food) for 21 days demonstrated a significant reduction in liver and gut Cu load relative to waterborne Cu exposure alone. Gene expression levels for divalent metal transport (DMT)-1, copper transporter (CTR)-1, and the basolateral metal transporter ATP7A in the gills and gut increased when compared with controls, but the various combinations of Cu and high-Fe diet revealed altered levels of expression. Further examination of the basolateral Fe transporter, ferroportin, showed responses to waterborne Cu exposure in the gut and a significant increase with Fe treatment alone in the liver. Additionally, we examined metallothionein 1 and 2 (MT1 and MT2), which indicated that MT2 is more responsive to Cu. To explore the relationship between transcription and protein function, we examined both CTR-1 protein levels and gill apical uptake of radiolabeled Cu64, which demonstrated decreased Cu uptake and protein abundance in the elevated Cu treatments. This study shows that high dietary Fe can significantly alter the genetic expression pattern of Cu transporters at the level of the gill, liver, and gastrointestinal tract.
authors.affiliation: Department of Biology, McMaster University, 1280 Main St. West, Hamilton, ON L8S 4K1 Canada. craigpm@mcmaster.ca
authors.forename: Paul M
authors.initials: PM
authors.lastname: Craig
authors.forename: Michal
authors.initials: M
authors.lastname: Galus
authors.forename: Chris M
authors.initials: CM
authors.lastname: Wood
authors.forename: Grant B
authors.initials: GB
authors.lastname: McClelland
mesh_terms: D000064:Acclimatization; D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D001835:Body Weight; D027682:Cation Transport Proteins / Q000378:metabolism; D003301:Copper Radioisotopes; D019327:Copper Sulfate / Q000633:toxicity*; D000079923:Copper Transporter 1; D000073840:Copper-Transporting ATPases; D005260:Female; D041981:Gastrointestinal Tract / Q000187:drug effects / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D005880:Gills / Q000187:drug effects / Q000378:metabolism; D019266:Iron, Dietary / Q000378:metabolism / Q000633:toxicity*; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D008297:Male; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D008668:Metallothionein / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects; D014874:Water Pollutants, Chemical / Q000633:toxicity*; D015027:Zebrafish / Q000235:genetics / Q000378:metabolism*; D029961:Zebrafish Proteins / Q000235:genetics / Q000378:metabolism*; D000098742:Ferroportin; D000099236:Solute Carrier Family 11, Member 2
chemical_list: D000251:Adenosine Triphosphatases; D027682:Cation Transport Proteins; D003301:Copper Radioisotopes; D019327:Copper Sulfate; D000079923:Copper Transporter 1; D000073840:Copper-Transporting ATPases; D019266:Iron, Dietary; D026901:Membrane Transport Proteins; D008668:Metallothionein; D014874:Water Pollutants, Chemical; D029961:Zebrafish Proteins; D000098742:Ferroportin; D000099236:Solute Carrier Family 11, Member 2; C515592:Atp7a protein, zebrafish; C486454:Slc31a1 protein, zebrafish