Characterization of circular YACs rescued in yeast. Chromosomal size DNA was isolated from 14 yeast transformants, exposed to a low dose of γ-rays, separated by TAFE, blotted, and hybridized with the D11S12 probe. The strong signals at the positions of the starting wells correspond to large circular molecules. The lagging bands correspond to circular molecules linearized by radiation. The weak hybridizing bands migrating between the 200-kb marker and the wells correspond to covalently closed forms of YAC DNAs. Each lane except lane 2corresponds to an independent Trp+ isolate. (Lanes 2,15) The same isolate. The size of the linearized YACs was determined by use of λ oligomers.
