Fig. 3.

Survival and DNA adduct formation in Xpa-WT and Xpa-Null HUFs treated with 3-NBA. (A) Cells were treated for 24 or 48 h with the indicated doses of 3-NBA and survival was measured using a crystal violet staining assay. Cells treated with 0.1% DMSO only served as control. Mean values are presented as% of control ± SD of 5 replicate wells and are representative of at least three independent experiments (variation ≤ 15%). (B) and (C) Cells were treated with 3-NBA (as indicated) for 48 h or 2 × 48 h and DNA adduct formation (RAL, relative adduct labelling) was assessed by ³²P-postlabelling. Values represent means ± SD of two biological replicates where each DNA sample was measured by two independent ³²P-postlabelling analyses. Due to severe loss of viability, DNA adduct formation was not assessed in Xpa-Null cells treated with 2 μM 3-NBA (indicated by skull and crossbones). (D) Autoradiographic profiles of DNA adducts obtained in 3-NBA-treated HUFs; arrows indicate spot 1: 2-(2′-deoxyadenosin-N⁶-yl)-3-aminobenzanthrone (dA-N⁶-3-ABA), spot 3: 2-(2′-deoxyguanosin-N²-yl)-3-aminobenzanthrone (dG-N²-3-ABA) and spot 4: N-(2′-deoxyguanosin-8-yl)-3-aminobenzanthrone (dG-C8-N-3-ABA). Spot 2 is a deoxyadenosine adduct that has not yet been structurally characterised. The origins, in the bottom left-hand corners, were cut off before exposure.