Generation of a germ cell nuclear factor conditional allele in mice.

Two recombination steps in embryonic stem (ES) cells were adopted to generate a floxed Germ Cell Nuclear Factor (GCNF) allele. First, a targeting vector containing a loxP site upstream of exon 4, encoding the DNA binding domain (DBD), and a floxed NeoTK double selection cassette downstream of exon 4 was integrated into the GCNF locus by homologous recombination. Second, a Cre-expressing vector was transiently introduced to remove the floxed NeoTK cassette via site-specific recombination. Heterogeneous ES cell populations were found in a single colony after Cre transfection and were separated using an ES cell re-pick step. Floxed GCNF mice were generated and had normal GCNF expression in the adult gonads. Using the Msx2Cre transgenic mice, the floxed GCNF can be completely deleted in the female germline. Taken together, the floxed GCNF mice were successfully generated and female germline deletion of the floxed GCNF allele was achieved using Msx2Cre mice. Copyright 2003 Wiley-Liss, Inc.