Genetic studies on metallothionein synthesis in the mouse: the induction of metallothionein by cadmium in inbred strains.

Differences in the Cd-induced levels of liver metallothionein in inbred mouse strains are described. All strains examined show substantial increases in metallothionein production after the administration of 25 mumol CdCl2/kg, but the maximal levels achieved after 48 hr differed such that CBA/Ca greater than DBA/2 greater than C57BL/10 = C3H/He greater than BALB/c. These differences were generally not paralleled by differences in the amount of Cd2+ bound to metallothionein or in the total tissue content of Cd2+. Incorporation of [35S]cysteine into metallothionein suggest that differential synthesis affecting both isoproteins (MT1 and MT2) equally is largely responsible for the strain difference between C57BL/10 and DBA/2, and interstrain crosses between these two strains reveal codominant inheritance of Cd2+-induced metallothionein level and indicate that a single gene, either linked or identical to the cdm gene on chromosome 3, is involved.