The Bacteriophage T7 Binary System Activates Transient Transgene Expression in Zebrafish (Danio rerio) Embryos

The bacteriophage T7 binary expression system is widely usedin vitrofor high level selective expression of cloned genes but its application toin vivomodels has not yet been investigated. In the present work, we show that coinjection into fertilized zebrafish eggs of pE1T7R, an expression plasmid bearing theT7 RNA polymerasegene driven by the cytomegalovirus (CMV) promoter, together with reporter vectors containing theEscherichia coli lacZgene driven by the T7 promoter, resulted in the efficient expression of the reporter gene in 24-h mosaic transgenic embryos. Conversely, embryos receiving an unrelated CMV-expression plasmid, instead of pE1T7R, lacked significant reporter gene activity, indicating the strict requirement of T7 polymerase to activate the T7 promoter in these embryos. The present study demonstrates the possibility of applying efficiently the bacteriophage T7 binary systemin vivoto a vertebrate model.