FIG. 3.

Presence of Ty1 circles. Undigested genomic DNAs were isolated from cells expressing wild-type Ty1 (WT), mutant Ty1 elements defective in IN (in-2600) or in the cPPT (cppt-74), or GAG-POL due to a +1 frameshift mutation early in GAG (FS) and cellular mutants defective in HR and NHEJ (dnl4Δ rad51Δ rad52Δ and dnl4Δ rad50Δ rad52Δ). Undigested genomic DNAs isolated from various cells were separated by agarose gel electrophoresis and analyzed by Southern hybridization using a ³²P-labeled TyA1-GAG probe. pBDG1198 (5,848 bp; refer to Materials and Methods) was used as a size marker for Ty1 (5,918-bp) linear and circular molecules. The positions of circular DNA containing single-strand breaks (NC), covalently closed circles (CCC), and linear DNA (L) and of linear size standards (in kilobases) are shown to the left. The relative amounts of linear and circular DNA were determined using phosphorimage analysis and normalized to the amount of integrated pGTy1 element present in genomic DNA.