Polymerase chain reaction amplification and functional characterization of sockeye salmon histone H3, metallothionein-B, and protamine promoters.

The histone H3 (H3), metallothionein-B (MT-B), protamine (PT) promoters of sockeye salmon were cloned by PCR using primers based on the DNA sequences of the rainbow trout promoters. Comparison of the DNA sequences of the sockeye salmon and the rainbow trout histone H3, MT-B, and PT promoters revealed that their DNA sequences and putative transcriptional cis-elements are remarkably conserved. Promoter activity of the sockeye salmon H3, MT-B, and PT promoters were examined by transfection studies using cell lines from fish and human. The H3 and MT-B promoters were shown to be active in all fish cell lines but were only weakly active in HeLa and GM637 cells. The MT-B promoter was also inducible by zinc and cadmium in RTH-149 cells. In contrast, the PT promoter was inactive in all fish cell lines. Transfection experiments also established that the HCMV IE promoter has very strong activity in the various fish cell lines. Our results suggest that the HCMV IE promoter and the sockeye salmon H3 and MT-B promoters are useful for the construction of expression vectors for transgenic and gene transfer studies in fishes.