Figure 3. Laser does not cause DNA damage (Non-genotoxic).

Plasmid cleavage assay was performed using PUC19 and following laser treatments with varying doses (a) and wavelengths (b) plasmid was analyzed by gel electrophoresis on 1% agarose gel that was quantitated by densitometry (n = 3). HaCaT (c) cells were treated with different doses of laser and genomic DNA was assayed for number of abasic sites. UV treatment was used as a positive control, Significance was based on one-way ANOVA with the respective controls (n = 3). (d and e) Ames test was performed on TA100 and TA98 strains of the Salmonella typhimurium using different doses of laser and revertants were quantitated on 5^th day after treatment. Significance was noted as per the manufacturer’s manual (n = 3). HaCaT cells (f) (Scale bars = 200 μm) or mice (g) were treated with phototoxic laser dose and γ-H2AX immunostaining was performed to assess DNA damage. γ-radiation (10 Gy) was used as positive control. Scale bars = 70 μm. (h) HaCaT cells were treated with radiation (10 Gy) and sub-phototoxic laser doses and PCR arrays were performed. Representative scatter plot of differentially regulated genes (fold change ≥ 2) are shown. Detailed list of genes are available in supporting materials (n = 2). Statistical significance are indicated as P < 0.0005 (***) and <0.00001(****).