Site-specific gene targeting for gene expression in eukaryotes

Major advances in the use of site-specific recombinases to facilitate susta ined gene expression via chromosomal targeting have been made during the pa st year. New tools for genomic manipulations using this technology include the discovery of epitopes in recombinases that confer nuclear localization, crystal structures that show the precise topology of recombinase-DNA-subst rate synaptic complexes, manipulations of the DNA recognition sequences tha t select for integration over excision of DNA, and manipulations that make changes in gene expression inducible by drug administration, in addition, e ndogenous eukaryotic and mammalian DNA sequences have been discovered that can support site-specific recombinase-mediated manipulations.