TRANSGENIC CRE RECOMBINASE EXPRESSION IN GERM-CELLS AND EARLY EMBRYOGENESIS DIRECTS HOMOGENEOUS AND UBIQUITOUS DELETION OF LOXP-FLANKED GENE SEGMENTS

We report on the establishment of a transgenic mouse line expressing C re recombinase under control of the c-kit promoter. Expression of Cre recombinase was only observed in late spermatogenesis and oogenesis, h owever, Cre-mediated deletion of flexed gene segments occurred at this stage as well as in early embryogenesis, As a consequence of this, a chimeric distribution of loxed alleles was found in a large fraction o f these mice, The chimerism was very homogeneous in different organs a nd tissues Elf the same individual but varied between different indivi dual offspring, The potential uses for this mouse line are discussed, (C) 1998 Federation of European Biochemical Societies.