Oxidative Stress-Mediated Overexpression of Uracil DNA Glycosylase in Leishmania donovani Confers Tolerance against Antileishmanial Drugs

Figure 6

ROS inducers (H₂O₂, menadione, and UVB radiation) upregulate LdUNG transcription in L. donovani. WT cells treated with H₂O₂ (a), menadione (b), and UVB radiation (c). RNA level of UNG gene was checked by RTPCR in L. donovani treated with drug for 30 min (1), treated with the same dose for longer duration, that is, 2 hours (2), and treated with the same concentration of drug for 30 min, washed, and maintained in fresh media for 4 hours (3). In the case of UV exposure, L. donovani treated with 28 mJ/cm² of UVB dose and RNA level of UNG gene was checked after 30 min (4), after 2 hours (5), and after 4 hours when maintained in fresh media after treatment (6). Relative abundance of UNG transcript was checked by RT-PCR, and the expression levels were normalized with that of alpha tubulin. The results are graphically represented as means ± SEM of three independent sets of experiments. Untreated parasites were used as control in the experiment. Data was analysed using one-way ANOVA, followed by Tukey’s multiple comparison test using GraphPad Prism 5.0. One-way ANOVA compares the relative fold change in the transcription levels (mean) of LdUNG in four unmatched groups (control, 1/4, 2/5, and 3/6) treated with oxidative agents (H₂O₂/menadione/UVB). The y-axis in all three bar graphs corresponds to relative fold change observed in the transcription level of UNG gene in L. donovani cells under different treatment conditions. , , and . ns, nonsignificant. For the meaning of these statistical symbols, refer to ligand of Figure 1.

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