FIG. 4.

Strategy for generating and genotyping MFng conditional and null alleles. (A) The MFng-targeting construct was generated by introducing loxP sites surrounding exon 4, which encodes the DXD glycosyltransferase motif that is required for Fringe function. Homologous recombination and Cre-mediated recombination events were evaluated by Southern blotting using a 5′ probe and a 3′ probe to detect KpnI or NheI restriction fragments as indicated. Routine genotyping of wild-type (WT) and null alleles was performed by PCR using primers MFng-G8, MFng-G9, and MFng-G2R as indicated. HSV-T, herpes simplex virus thymidine kinase cassette. (B) Southern blotting of KpnI-digested genomic DNA probed with the 3′-end-flanking probe (A) detects the wild-type (+), conditional (3loxP), and null (−) alleles of MFng. For construction details, see Materials and Methods.