Southern blot analysis of
end joining products. DSB substrate XM was incubated with HeLa whole
cell extract as described in Materials and Methods. After the end
joining reaction, substrate DNA was recovered, resolved by 0.8% agarose
gel electrophoresis and analyzed by Southern hybridization using
random primed M13mp18 as probe as described in Materials and Methods.
H, heated-inactivated whole cell extract control; C, complete reaction;
T4, reaction containing 0.5 Weiss U T4 ligase in the absence of
cell extract. The DSB substrate linear monomer and various product
forms are annotated on the left: LM, linear monomer; OCM, open circular
monomer; LD, linear dimer; MM, other multimeric forms.