Regulation in vivo of a cloned mammalian gene: cadmium induces the transcription of a mouse metallothionein gene in SV40 vectors.

Cadmium and other heavy metals induce metallothionein synthesis in mammalian cells. We have cloned a mouse metallothionein-I gene from a cadmium-resistant line of Ltk- cells and inserted it into viral and plasmid SV40 vectors. These recombinant molecules were introduced into cultured monkey cells and the expression of the foreign metallothionein gene was analyzed, at the RNA level, in the presence and absence of cadmium. The results show that the cloned gene retains its cadmium inducibility and that the regulation of this gene occurs primarily at the transcriptional level.