Cloning and characterization of excision repair genes

For all living organisms, it is of vital importance to maintain intact the genetic information stored in the nucleotide sequence of DNA. Numerous environmental and genotoxic agents can affect the DNA and lead to, for example, mutagenesis or carcinogenesis. Study of the mechanism of UV-carcinogenesis has become even more pressing given recent concerns about atmospheric ozone depletion (Mimms, 1994; Watson, 1995), because such atmospheric alterations would result in increased UVB at the earth's surface. Carcinogenesis appears to be a multistep process through which normal cells progress from benign, through transitional stages to the fully malignant forms of cancer by the gradual accumulation of genetic errors (Bishop, 1995). Therefore, normal cells have an intricate quality control mechanism that recognizes and mends damage to the DNA helix.