R-loop formation on pSK-(AGGAG)22 and effects of RNase T1 on the formation. A plasmid containing a (AGGAG)22 repeat was transcribed with T7 RNA polymerase and the effects on the topology of the plasmid were examined by agarose gel electrophoresis. (a) Lane 1: mock transcribed; lane 2: transcribed with T7 RNA polymerase; lane 3: transcribed with T3 RNA polymerase. (b) lane 1: mock transcribed, lane 2: transcribed with T7 RNA polymerase, Lane 3: transcribed with T7 RNA polymerase in the presence of 3 units of RNase T1; lane 4: transcribed with T7 RNA polymerase and ethanol-precipitated; and lane 5: transcribed with T7 RNA polymerase, ethanol-precipitated, and then incubated with 3 units of RNase T1.
