DEVELOPMENT OF A HEAVY METAL-INDUCIBLE FISH-SPECIFIC EXPRESSION VECTOR FOR GENE-TRANSFER INVITRO AND INVIVO

The promoter of the rainbow trout metallothionein B gene (tMTb) was is olated from genomic DNA by the polymerase chain reaction (PCR), fused to the bacterial chloramphenicol acetyltransferase (CAT) gene in an ex pression vector, and functionally analyzed in one human cell line and four fish cell lines. This promoter exhibited an extremely low basal e xpression in all cell lines and was zinca- and cadmium-inducible excep t in the fish melanoma cell line where the promoter was completely ina ctive. The metal-induced expression patterns were cell line-specific. In general the fish promoter was more species- and cell type-specific than its human counterpart. In a transient assay it was functional in developing embryos of the medaka (Oryzias latipes). These properties m ake this promoter suitable for inducible, tissue-specific expression o f transgenes and for in vivo studies of gene function and regulation.