Figure 1.—

DSB repair substrate pTNeo99-7. Shown is plasmid pTNeo99-7 linearized at the unique XhoI site (X) in the vector. The substrate contains a hygromycin-resistance gene (hyg) and a tk-neo fusion gene. The tk-neo fusion gene is disrupted by a 22-bp oligonucleotide containing the 18-bp recognition site for endonuclease I-SceI (underlined sequence); the sites of staggered cleavage by I-SceI are indicated by vertical arrows. Also shown are two BamHI sites (B) flanking the tk-neo fusion gene and the location of primers AW85 and AW91 (short horizontal arrows) used in PCR analysis. Primer AW85 maps within tk sequences and AW91 maps within neo sequences; the two primers are positioned 1.4 kb apart.