FIG. 1.

Generation of a Jag2 conditional null allele. (a) Schematic representation of a portion of the wildtype Jag2 allele, the Jag2^floxneo targeting vector, and the targeted Jag2^floxneo allele. Exons are indicated by boxes with coding sequences designated by dark shading. LoxP sequences are marked by triangles and FRT sites by gray rectangles. The FRT-PGKneo-FRT-LoxP- cassette was inserted between exons 2 and 3 and the second LoxP site was inserted 5′ to exon 1, approximately 1.1 kb upstream of the Jag2 translational start site. A diphtheria toxin (DT) cassette was included for negative selection of randomly integrated clones. The hybridization probe used for Southern blot analysis is indicated. Abbreviations: H, HindIII; S, ScaI; Sa, SacI. (b) Southern blot analysis of targeted ES cells. HindIII or ScaI digested ES cell genomic DNA was hybridized with the 5′ or 3′ probe respectively as indicated in a, yielding 14 kb wildtype and 4 kb mutant bands for the 5′ probe, and 11 kb wildtype and 5.4 kb mutant bands for the 3′ probe. M: markers.