Figure 1.

Targeted disruption of the Cry1 gene. (A) Targeting of the Cry1 locus. The construct (1) was used to target the Cry1 gene (2) in the E14 g2a embryonic stem cell line. Homologous recombination leads to the deletion of a 13-kb genomic region [stippled box in (2)] containing exon sequences encoding the FAD-binding domain. The targeted allele (3) is detected by a probe as shown, with the expected DNA fragment sizes as indicated. Solid boxes, identified coding sequences; SA, Engrail-2 splice acceptor; S, SalI; Xb, XbaI; Xh, XhoI (restriction sites). (B) Identification of targeted mutants by Southern hybridization. The 2.5-kb mutant and the 6.6-kb wild-type fragments resulting from Xba digestion are indicated.