FIG 5.

Detection and quantification of 8-oxo-G in genomic-DNA samples isolated from different B. subtilis strains grown in the presence of Cr(VI). (A) Chromosomal DNA was purified from cell cultures of B. subtilis WT (lanes 1 to 4) and ΔGO (lanes 5 to 8) strains that were grown in the absence (lanes 1, 2, 5, and 6) or presence (lanes 3, 4, 7, and 8) of a Cr (VI) concentration equivalent to the LD₉₀ for each strain. DNA samples (∼5 μg) were treated (lanes 2, 4, 6, and 8) or not (lanes 1, 3, 5, and 7) with 14 units of the enzyme Fpg, as described in Materials and Methods. Reaction mixture samples were electrophoresed on a 1% alkaline agarose gel that was then stained with ethidium bromide, as described in Materials and Methods. The results shown are representative of two experiments that yielded essentially similar results. CD, high-molecular-weight chromosomal DNA. (B) Chromosomal DNA was purified from cell cultures of B. subtilis WT and ΔGO strains grown in the absence (white bars) or presence (gray bars) of a concentration of Cr(VI) equivalent to the LD₉₀ for each strain. DNA samples (30 μg) from each strain and experimental condition were used to quantify the levels of 8-oxo-G, using a specific anti-8-oxo-G antibody with an ELISA kit, as described in Materials and Methods. The values represent the average and SEM of two independent experiments done in triplicate for each sample. The asterisks indicate values that were significantly different.