MEPS 177:189-196 (1999)  -  doi:10.3354/meps177189

210Po binding to metallothioneins and ferritin in the liver of teleost marine fish

J. P. Durand1,*, F. P. Carvalho2, F. Goudard1, J. Pieri1, S. W. Fowler2, O. Cotret2

1Université de Nantes, Faculté des Sciences, GERMETRAD, Laboratoire de Biochimie et Radiobiochimie, 2 rue de la Houssinière, BP 92208, F-44322 Nantes Cedex 3, France
2International Atomic Energy Agency, Marine Environment Laboratory, BP 800, MC-98012 Monaco Cedex

ABSTRACT: The subcellular distribution of the naturally occurring radionuclide 210Po was investigated in the liver of the Atlantic mackerel Scomber scombrus. The majority of the 210Po was found in the cytosol of the liver cells. Fractionation of the cytosol proteins by high performance size-exclusion and ion-exchange chromatography indicated that about 30% of 210Po was bound to ferritin and approximately 28% to metallothioneins. The affinity of 210Po for these proteins was confirmed by a similar binding of the artificial 208Po isotope incubated in vitro with the cytosolic proteins. Two other proteins, likely selenium- and zinc-containing enzymes, may also bind smaller amounts of 210Po, about 8% each. The extensive binding of 210Po to ferritin and metallothioneins is not accompanied by a similar strong binding of 210Pb, the radioactive grandparent of 210Po, which explains the generally very high 210Po:210Pb ratio observed in fish tissues and, in particular, fish liver.

KEY WORDS: Polonium · Fish · Metallothionein · Ferritin

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