Figure 1.

Inhibition of LoxP recombination during second passage through the germline. (A) Diagram of the floxed Kdm1a locus. The two CpG residues in the 34 bp LoxP recognition sequence are underlined. (B) Diagram of the original cross scheme used to generate germline Kdm1a conditional knockout mice. In F1 mice, the floxed Kdm1a locus deletes with 100% efficiency. However, in the germline of F2 mice, the LoxP sites are largely inhibited from recombining. This was determined by genotyping the resulting F3 progeny (see Materials and Methods and Figure S1 for details). (C) Sample genotyping showing the ability to distinguish all possible genotypes during the crosses.