Embryonic stem cells containing recombinase transgenes that are expressed in the male germ line, but not in other tissues or in the embryonic stem cells themselves, substantially simplify the production of subtle or conditional mutations in mice. This strain shows that transgenes comprised of the mouse protamine 1 promoter and the Cre recombinase coding sequence mediate the efficient recombination of a Cre target transgene in the male germ line, but not in other tissues. This system can be used for reducing the time, effort, and resources required to produce homologously recombined alleles in mice that have been secondarily rearranged by site-specific recombinase.
In an attempt to offer alleles on well-characterized or multiple genetic backgrounds, alleles are frequently moved to a genetic background different from that on which an allele was first characterized. This is the case for the strain above. It should be noted that the phenotype could vary from that originally described. We will modify the strain description if necessary as published results become available.
