T7 AM Metals in the Environment: Dietary Concerns in Aquatic Systems
Tuesday, 15 November 2005: 8:00 AM - 11:40 AM in 327-329

(BUR-1117-731451) A low-iron diet increase cadmium accumulation in fish.

Bury, NR¹, Cooper, C¹, Handy, R², ¹ King's College London, London, United Kingdom² University of Plymouth, Plymouth, Uniteed Kingdom

ABSTRACT- Intestinal uptake of non-haem bound iron in mammals occurs predominantly in the ferrous (Fe²⁺) form via a Fe²⁺/H⁺ symporter. Homologs to this symporter have been identified in teleost fish and have been shown to transport a wide range of divalent metals (e.g. Fe, Cd, Pb, Zn, Co) and are thus known as divalent metal transporter 1 (DMT1). Zebrafish (Danio rerio) were fed a low or high iron diet (33 and 95 mg Fe kg^-1, respectively). After 10 weeks short-term (4h) Fe and Cd uptake by the intestine and gills were assessed. Whole body essential metal Fe, Mn, Cu, and Zn concentrations were measured and transcript levels of DMT1 and an iron export protein, ferroportin, were measured in the intestine and gill. Fish fed the low iron iron diet show increased intestinal Fe and Cd uptake in diet, and results suggest an increase in the affinity for gill Fe and Cd uptake. Gill and intestine DMT1 transcript levels increased in fish fed a low iron diet, whereas ferroportin expression only increased in the intestine in these fish. Whole body Fe, Mn, Cu, Zn concentrations were all increased in fish fed the low-iron diet. These results show that fish fed a low iron diets diet may show no signs of low iron status (e.g. reduced whole body Fe concentrations), but show an increase in expression of epithelial iron transporters, with a parallel increase in metal uptake. Long-term feeding of low-iron diets to fish may lead to an increase in toxic metal accumulation from the intestine.

Key words: divalent metal transporter, Dietary cadmium toxicity, freshwater fish, fish health