Reliable Comet assay measurements for detecting DNA damage induced by ionising radiation and chemicals

In vitro cytotoxicity and genotoxicity studies of titanium dioxide (TiO2) nanoparticles in Chinese hamster lung fibroblast cells

“…Our genotoxicity findings agree with earlier studies in the induction of DNA damage in cells after exposure to nano-TiO 2 , and a stronger induction was observed in nano-sized anatase compared to rutile. The olive tail moment and the percentage of DNA in the tail (% tail DNA), which are the most informative and reliable measurements (Kumaravel and Jha, 2006;Olive and Durand, 2005), were used as DNA damage indicators in our study. Neither the % tail DNA nor the olive tail moment was shown to be significantly different in cells exposed to Vive Nano Titania compared to negative control groups (Fig.…”

“…5f). The percentage of DNA in the comet tail (% Tail DNA) and the olive tail moment (OTM) from 50 cells in each of two replicate samples were used to measure DNA damage; these two parameters are considered as the most informative and reliable measurements (Kumaravel and Jha, 2006;Olive and Durand, 2005). A large tail was detected in the nucleus of each cell treated with the 100 μM hydrogen peroxide positive control group (data not shown).…”

Comet Assay measurements: a perspective

“…They measured fluorescence (using photometre) in the head and in the tail at a distance of 50 μm from the centre of the head using acridine orange as the DNA binding dye Tail length, Tail DNA and DNA distribution profile in the Tail are primary Comet Assay measurements (obtained by fluorescent densitometric profiles of the comets). All other measurements are derived from the three primary Comet Assay measurements (adapted from Kumaravel and Jha 2006). background fluorescence adjacent to the cells was subtracted. The time of illumination and between measurements were standardised to minimise fading bias.…”

“…Currently, the Comet Assay has however the potential to be used as a tool in genotoxicity testing and regulatory submissions for new chemicals and mixtures (Tice et al 2000;Hartmann et al 2003;Kumaravel and Jha 2006). In an attempt to make the assay more sensitive and reliable, several research groups have come out with unique procedures and specialised measures of DNA migration.…”

“…However, for peer-review publications, normally, only one set of measurements (e. g. either tail moment or % Tail DNA) is presented. Kumaravel and Jha (2006) defined the most reliable comet measurements that would truly reflect the extent of DNA damage induced by low linear energy transfer ionising radiation. The authors approached this question by performing alkaline Comet Assay on human peripheral blood lymphocytes irradiated with graded doses of 137 Cs gamma radiation and correlating the various comet measurements with the radiation dose.…”