VIRAL SEQUENCES ENABLE EFFICIENT AND TISSUE-SPECIFIC EXPRESSION OF TRANSGENES IN XENOPUS

Expression of transgenes within a single generation by direct DNA inje ction into vertebrate embryos has been plagued by inefficient and nonu niform gene expression. We report a novel strategy for efficient and s table expression of transgenes driven by both ubiquitous and tissue-sp ecific promoters by direct DNA injection into developing Xenopus laevi s embryos. This strategy involves flanking expression cassettes of int erest with inverted terminal repeat sequences (ITRs) from adeno-associ ated virus. Our results suggest that the ITR strategy may be generally applicable to other systems, such as zebra fish and embryonic stem ce lls, and may enable tissue-specific expression of transgenes in proble matic contexts.