Fig. 5.

Replication-dependent and independent Z-DNA-induced genetic instability in mammalian cell extracts. (A) Replication-proficient (Left) and replication-deficient (Right) Z-DNA-induced mutagenesis in HeLa cell extracts. The number of mutants observed and the total number of colonies screened are listed below the corresponding bars. Error bars show the SEM of three independent experiments. (B) Restriction analysis of mutants generated in replicated (Left) and unreplicated (Right) systems. ∗ refers to large-scale deletions (≥50 bp); C refers to control sample. (C) Z-DNA-induced cleavages in HeLa cell extracts in the absence of replication. The positions of three restriction sites on the plasmid, pUCNIM, are shown schematically above. The Z-DNA locus is marked with ∗. A radiolabeled 630-bp fragment containing breakages generated in HeLa cell extracts is indicated by an arrow.