Injection of the mouse MT-1 gene into rainbow trout eggs and assay of trout fry for resistance to cadmium and zinc toxicity.

The mouse MT-1 gene, cloned into the plasmid pBR 322, has been injected into fertilised eggs of the rainbow trout, Salmo gairdneri. About 10(6) copies of the construct, either circular or linearized, have been injected into 1 cell stage eggs within 4 hours of fertilisation, and fry hatched from such eggs are being assayed for evidence of integration of the injected sequence. In addition, with a view to the development of an assay which can be used to monitor for expression of the injected gene, uninjected fry have been exposed to various concentrations of cadmium chloride or zinc sulphate, with or without prior exposure to inducing doses of these compounds. Whereas a distinct protection is evident following induction with zinc, no such protection has been detected with cadmium induction.