Induction and turnover of catfish (Heteropneustes fossilis) metallothionein.

Induction of metallothionein by cadmium in catfish was a dose-dependent, transcriptionally-controlled process. Metallothionein mRNA was detected after Cd-exposure. Chronic doses produced more metallothionein than a single acute dose. Zn and Cu induced metallothionein to a lower extent compared to Cd. A few other low molecular weight proteins were induced in cadmium-exposed catfish liver, besides metallothionein. Isoelectric point of catfish metallothionein was 3.9. The rate of depletion of Cd and metallothionein was very slow from liver and almost unchanged from kidney following its induction by cadmium.