Abstract
Comet assay, also called single cell gel electrophoresis (SCGE), is widely used to investigate genotoxin, and DNA repair system. UVC induced DNA adducts were cyclobutane pyrimidine dimmers (CPD) and 6-4 pyrimidine pyrimidone photoproducts (6-4PP). These adducts do not caused DNA breaks immediately, the DNA breaks were the intermediate of repair process that means conventional comet assay can’t estimate total amounts of UVC induced DNA adducts. To overcome this problem, people who demonstrated that damaged DNA was incubate with nuclear extract (NE) or T4 endonuclease V (Den V) to excised DNA adducts that would enhance the sensitivity of comet assay when UVC as damage source. In this study, I focused on the application of comet-NE assay. I found that comet-NE assay can detect more UV-induced DNA adducts than Den V. Besides, the accuracy of comet-NE assay also verified by distinguish different repair kinetic between XP22VI and MSU-1 cells. The well established comet-NE and comet-Den V assay were used to study repair kinetic of bladder cancer cells and colcemid effect on NER process.