Effect of chronic non-lethal doses of non-metals and metals on hepatic metallothionein in Channa punctatus (Bloch).

Compared to non-metal toxicants (ammonia, 1.56 ppm; and phenol, 10 ppm), the metals (CdCl2, 30 ppm; HgCl2, 16.7 ppb; and ZnCl2, 6 ppm) significantly induced hepatic metallothionein (MT) concentrations in C. punctatus, exposed independently to non-lethal doses of these toxicants for 28 days. It is suggested that hepatic MT serves as a metal-sequestering protein and is involved in the detoxication of metals only and ensures protection from toxic chemicals in ambience.