ZINC-INDUCED ACTIVATION OF RAINBOW-TROUT METALLOTHIONEIN-A PROMOTER IN TRANSGENIC MEDAKA

Zinc-induced activation of rainbow trout metallothionein-A (rtMT-A) pr omoter was investigated in transgenic medaka using chloramphenicol ace tyltransferase (CAT) gene as a reporter. The plasmid prtMT-A-CAT conta ining rtMT-A promoter and CAT gene was microinjected into medaka ferti lized eggs at the one-cell stage. Hatched fry, in which the transgene was detected by PCR, were exposed to 0 to 100 muM of ZnCl2 and the pro moter activity was monitored by CAT assay. The activity was induced do se-dependently at concentrations of ZnCl2 over 1 muM. These results su ggest that the rtMT-A promoter was useful for controlling expression o f transgenes in transgenic fish by experimental conditions.