ABSTRACT
This chapter deals with the cellular controls, biochemical and cytological toxicities of pollutant and essential trace metals, and assessments of toxicities in marine animals. Several trace metals are chemically highly reactive and while they are essential and show a "beneficial" dose response curve at low concentrations, with increasing concentration, they may become inhibitory and ultimately toxic. The most studied and well characterized are the metallothioneins (MTs), a group of low molecular weight proteins unique in their high cysteine content and paucity of aromatic amino acid residues. MTs and MT-like proteins have been reported in many marine animals from sea urchins to mammals. Cu-MT is extremely susceptible to oxidation and when significant quantities are present it polymerizes and accumulates in lysosomes. Immobilization of metals by sequestration in lysosomes represents a major nonspecific mechanism for detoxification of many metals in animals exposed to excessively high levels.
