Figure 4.

The effect of spermidine on the resolution of supercoiled alpha-structure excisive junctions. The substrates used to generate the junctions are shown at left (EtBr-stained panel), and are a supercoiled plasmid with attR and a double end-labeled 900 bp fragment with an attL site. The extent of resolution is indicated below the gel (%Res) along with the ratio of forward to reverse resolution products (For/Rev). Forward resolution results in a long linear molecule, labeled ‘prod (F)’. Reverse resolution results in the same molecules that were used to make the junction, only one of which is labeled [the 900 bp fragment labeled ‘sub (R)’]. The second substrate, marked with a *, is unlabeled, and thus invisible on the phosphorimage. This gel is representative of three independent experiments.