Site‐specific transgenesis in Xenopus

Transgenesis is an essential, powerful tool for investigating gene function and the activities of enhancers, promoters, and transcription factors in the chromatin environment. In Xenopus , current methods generate germ‐line transgenics by random insertion, often resulting in mosaicism, position‐dependent variations in expression, and lab‐to‐lab differences in efficiency. We have developed and tested a Xenopus FLP‐FRT recombinase‐mediated transgenesis (X‐FRMT) method. We demonstrate transgenesis of Xenopus laevis by FLP‐catalyzed recombination of donor plasmid cassettes into F 1 tadpoles with host cassette transgenes. X‐FRMT provides a new method for generating transgenic Xenopus . Once Xenopus lines harboring single host cassettes are generated, X ‐FRMT should allow for the targeting of transgenes to well‐characterized integration site(s), requiring no more special reagents or training than that already common to most Xenopus labs. genesis 50:325–332, 2012. © 2012 Wiley Periodicals, Inc.