Indian Institute of Toxicology Research, Mahatma Gandhi Marg, Uttar Pradesh, India.
Mutat Res. 2011 Apr 3;721(2):142-6. doi: 10.1016/j.mrgentox.2011.01.010. Epub 2011 Jan 31.
Comet assay under neutral conditions allows detection of DNA double-strand breaks (DSBs), which has consequence to genome instability and carcinogenesis. The present study aims to validate the neutral Comet assay for genotoxicity assessment in Drosophila melanogaster (Oregon R(+)) with three well known DSBs inducers i.e. cyclophosphamide (CP), bleomycin (BLM), cisplatin (CPT) and subsequently its efficacy in detecting DSBs in the organism exposed to a well known environmental chemical, chromium [Cr(VI)]. Third instar larvae of D. melanogaster were fed different concentrations of BLM, CPT and CP (50.0-200.0μg/ml) or Cr(VI) (5.0-20.0μg/ml) mixed standard Drosophila food for 48h. Neutral Comet assay was performed in cells of mid gut and brain from control and treated larvae. Our results show a dose-dependent increase in the migration of DNA in cells of the exposed organisms. A comparison among DNA lesions per mole number of the test chemical in the exposed groups showed that both BLM and CPT induce more DSBs than CP. Interestingly, Cr(VI) at 20.0μg/ml was found to induce significantly increased (p<0.001) DSBs in the exposed organism as compared to the control. The study while validating neutral Comet assay in D. melanogaster suggests its use for in vivo assessment of environmental chemical induced DSBs.
中性彗星试验可检测 DNA 双链断裂（DSBs），这会导致基因组不稳定和致癌。本研究旨在利用三种已知的 DSB 诱导剂（即环磷酰胺（CP）、博来霉素（BLM）、顺铂（CPT））验证中性彗星试验在黑腹果蝇（Oregon R(+））中的遗传毒性评估，随后评估其在检测暴露于已知环境化学物质铬[Cr(VI）]的生物体中的 DSBs 的功效。黑腹果蝇的三龄幼虫用不同浓度的 BLM、CPT 和 CP（50.0-200.0μg/ml）或 Cr(VI）（5.0-20.0μg/ml）混合标准果蝇食物喂养 48 小时。在对照和处理幼虫的中肠和大脑细胞中进行中性彗星试验。我们的结果显示，暴露于受试化学物质的生物体的细胞中 DNA 的迁移呈剂量依赖性增加。暴露组中每摩尔测试化学物质的 DNA 损伤的比较表明，BLM 和 CPT 诱导的 DSB 比 CP 多。有趣的是，与对照组相比，Cr(VI）在 20.0μg/ml 时被发现可显著增加（p<0.001）暴露于化学物质的生物体中的 DSB。该研究在黑腹果蝇中验证了中性彗星试验，表明其可用于体内评估环境化学物质诱导的 DSB。
