Waterborne iron acquisition by a freshwater teleost fish, zebrafish Danio rerio

Nicolas R. Bury, Martin Grosell

Research output: Contribution to journalArticle

44 Scopus citations

Abstract

Waterborne iron accumulation by the gills of the zebrafish Danio rerio was assessed in ion-poor water. Branchial iron uptake, which comprises both the iron that has entered the gill cells and iron that is strongly bound to the epithelia, has high- and low-affinity components. At low nominal [Fe] (<40 nmol l-1) the high-affinity component demonstrated saturation kinetics, with an apparent Km of 5.9 nmol l-1 Fe and Vmax of 2.1 pmol g-1 h-1. Over a range of higher nominal [Fe] (40-200 nmol l-1), branchial uptake was linear. In the presence of 2 μmol l-1 of the reducing agent dithiothreitol (DTT), branchial iron accumulation was significantly enhanced at [Fe]>15 nmol l-1. The proton pump inhibitor bafilomycin A significantly reduced iron uptake in the presence of DTT. On the basis of these observations we conclude that branchial iron uptake at low [Fe] shows characteristics similar to those of other iron-transporting epithelia, coupling an apical membrane ferric reductase to a Fe2+/H+ symporter. Zebrafish branchial iron transport at 18.6 nmol l-1 was inhibited by 200 nmol l-1 Cd2+. But, unlike other Fe 2+/H+ symporters, iron uptake was not affected by other divalent metals (Co2+, Ni2+, Pb2+, Cu 2+, Zn2+ and Mn2+). Zebrafish loaded with 59Fe from the water showed a loss of 7.9 pmol Fe g-1 body mass over the first day and a further loss of 5.7 pmol Fe g-1 body mass over the following 28 days. The depuration kinetics followed a two-component exponential model; for the short-lived component, t 1/2=0.31 days, and for the long-lived component, t1/2=13. 2 days. The daily iron loss by zebrafish can be compensated by iron uptake at exceedingly low water iron concentrations (uptake rate at 1.625 nmol l -1 Fe=0.425 pmol g-1 h-1), demonstrating that uptake of iron from the water is potentially an important source of this nutritive metal in freshwater teleost fish.

Original languageEnglish (US)
Pages (from-to)3529-3535
Number of pages7
JournalJournal of Experimental Biology
Volume206
Issue number19
DOIs
StatePublished - Oct 1 2003

Keywords

  • Danio rerio
  • Divalent metal transporter (DMT)
  • Ferric reductase
  • Ferroportin
  • Fish nutrition
  • IREG
  • Iron bioavailability
  • Metal
  • Teleost
  • Zebrafish

ASJC Scopus subject areas

  • Agricultural and Biological Sciences(all)
  • Agricultural and Biological Sciences (miscellaneous)

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