01976naa a2200217 a 450000100080000000500110000800800410001910000200006024500990008026000090017952013960018865000090158465000190159365000100161265000100162265000120163265300180164465300100166270000180167277300680169017848162017-04-05       1986    bl ---       0--  u    #d1 aHAMILTON, S. J.  aMetallothionein in fishbreview of its importance in assessing stress from metal contaminants.  c1986  aMetallothionein, a low-molecular-weight protein whose apoprotein, thionein, is induced by exposure to cadmium, copper, mercury and zinc, plays an important role in the transport and storage of heavy metals; it also provides a protective role against the toxic effects of these metals by sequestering and thus reducing the amount of the free metal ions. Interest in the detoxification role of metallothionein in fisheries research and aquatic toxicology has increased because of the increasing contamination of aquatic habitats by heavy metals. Reports of laboratory and field investigations have shown that metallothionein synthesis is induced in fishes during chronic and acute exposures to metals. There is also evidence of the presence in fish of low-molecular-weight inorganic-binding proteins that are different from metallothionein, as well as evidence that cadmium is not sequestered by metallothien in rainbow trout Salmo gairdneri. The sequestering of metal contaminats by metallothionien and sunsequent toxic effects in fish and other animals has been described be the spillover hypothesis, which states that once metallothionein is saturated by metals, excess ions spill over into other cellular compartments and cause pathological lesions. We review the literature on metallothionen in fish, and emphasize the protein role in the detoxification and binding of metal contaminants.  afish  aContaminação  aMetal  aPeixe  aTóxico  aContamination  aToxic1 aMEHRLE, P. M.  tTransaction American Fisheries Societygv.115, p.596-609, 1986.