Research Paper Volume 8, Issue 10 pp 2449—2462

Figure 2. DNA damage induced by the activation of miniSOG and tKR targeted to chromatin. (A-B) Asynchronous H2B-miniSOG expressing HeLa cells, along with their non-expressing counterparts, were either blue-light irradiated (“BL”; 465-495 nm, 65 mW/cm², 5 min) or light irradiated and recovered for 30 min (“BL+rec”). Asynchronous H2B-tKR expressing HeLa cells, along with their non-expressing counterparts, were either green-light irradiated (“GL”; 540-580 nm, 200 mW/cm², 15 min) or light irradiated and recovered for 30 min (“GL+rec”). Alkaline (A) and neutral (B) comet assays were performed. Non-illuminated cells were used (“control”) as a negative control and cells treated with H₂O₂ (“H2O2”; 200 μM, 1 hr) were used as a positive control in the alkaline comet assay (A), and cells treated with the topoisomerase II poison etoposide (“VP16”; 10 μg/ml, 1 hr) were used as a positive control in the neutral comet assay (B). Box plots show the tail moments. The boxed region represents the middle 50% of the tail moments, the horizontal lines represent the medians, and the black crosses indicate the means. *P < 0.0001 (two-tailed t-test, n > 70), ^#P < 0.0001 (two-tailed t-test, n > 150), n.s. – not significant. The results of one of four experiments are shown.