The floxed sequences of Dmrt1tm1Zark were deleted by mating mice carrying this allele to the cre-expressing TgN(ACTB-cre)2Mrt line. The cre-mediated recombination event removes the promoter, the major translation initiation codon, exon 1 (which contains the zinc-finger-like DM domain), the neomycin resistance gene, and part of intron 1. Homozygous mutant animals did not express protein product as demonstrated by immunohistochemical analysis of testes sections. (J:65541)