Figure 1.

Targeted disruption of the Naglu gene. The structure of the endogenous gene, the targeting construct, and the disrupted allele are presented schematically on successive lines. Southern blot identification of the disrupted gene is shown (Bottom): embryonic stem cell colonies (Left) and F2 mice (Right). These were identified by hybridization of the 5′ probe to EcoRI restriction fragments. The fragment is smaller in the disrupted allele than in the normal one (9.5 kb vs. 15.5 kb) because of the presence of an EcoRI site in the neo^r gene. Hybridization with the 3′ probe gave a 6-kb fragment for the disrupted allele (not shown). Filled rectangles represent exons, whereas the open rectangle at the 5′ end indicates that the transcription start site has not been defined. The two bars under the disrupted allele represent the 5′ and 3′ probes used for Southern blots. Abbreviations for restriction enzymes are: RI, EcoRI; SI, SacI; X, XhoI; B, BamHI; (X) indicates that the XhoI site was lost during the cloning process.