Evidence for F14512-specific Topo II-mediated cleavage in moderately repeated <i>Drosophila</i> sequences.

<p>(A) <i>Hin</i>dIII-digested DNA samples from S2 cells treated for 30 minutes with no drug (lanes 1and 7), F14512 (5, 10, 25 or 50 µM, lanes 2–6 and 9–12) or 50 µM TOP-53 (lanes 2 and 8), in the absence (lanes 1–7) or presence (lanes 8–12) of 25 µM distamycin (DIST). Purified DNA samples were hybridized to a labeled <i>Hin</i>fI-digested whole genomic DNA probe that had been pre-hybridized as described in Materials. The a–b–c fragments indicated to the right of the gel are described in the text. (B) Densitometric scan of the autoradiograph shown in (A) for lanes 7, 8 and 11. Regions corresponding to fragments a, b and c are indicated by arrowheads. (C) S2 cells were treated for 30 minutes with no drug (-), F14512 (25 or 50 µM) or 50 µM etoposide in the presence of 25 µM distamycin (DIST). Purified DNA samples were processed as described in panel A. Fragments a, b and c are indicated by arrowheads to the left of the gel, which provides better resolution of the a–b regions.