Transposon-mediated enhancer trapping in medaka.

We tested the Sleeping Beauty transposable element for its ability to efficiently insert transgenes into the genome of medaka (Oryzias latipes), an important model system for vertebrate development. We show that the SB transposon efficiently mediates integration of a reporter gene into the fish germ line. In pilot experiments, we established 174 transgenic lines with a transgenesis efficiency of 32%. Transgenes are stably transmitted to, and expressed in, subsequent generations. Interestingly, the transgenic lines show novel expression patterns with temporal and spatial specificity at a rate of 12% (21/174), likely due to both, enhancing and silencing position effects. Furthermore, promoter-dependent GFP expression in injected fish embryos is tightly correlated with germ line transmission, facilitating easy selection of founder fish. Thus, the SB transposon/transposase system provides a highly efficient tool for transgenesis in general and for the generation of novel reporter gene expression patterns in particular.