Figure 1.

Disruption of the cgt locus in mouse ES cells and generation of CGT-deficient mice. (A) Targeting strategy: the murine cgt-coding exon I is indicated by a closed box. The neo^r cassette inserted into the KpnI site of exon I and the HSV-tk gene (▨) has been placed upstream of the exon I. B, BamHI; E, EcoRI; S, SacI; K, KpnI. Homologous recombination introduces an additional BamHI site through the pgk neo cassette. (B) Southern blot hybridization analysis of BamHI-digested ES cells and tail DNA from offsprings of cgt^+/− intercrosses. neo probe is a 1.1-kb fragment; 3′-probe a 1.1-kb EcoRI fragment (3) coresponding to a genomic sequence downstream of the replacement sequence.