DETECTION OF POINT MUTATIONS IN T-LYMPHOCYTES

We exposed experimental animals to a series of alkylating agents that induced mutations at the X-linked hprt gene of T lymphocytes. We then isolated the mutant cells and analyzed the molecular nature of the mut ations by amplification of hprt cDNA sequences with the use of reverse transcriptase PCR followed by DNA sequence analysis, and then correla ted the mutational spectra obtained to the spectra of DNA adducts caus ed by the alkylating agents used. The nature of the base-pair changes causing the mutations was characteristic for the reaction pattern of t he genotoxic agent with DNA. However, we also found a clear influence of DNA repair processes; i.e., in those cells that were able to remove certain types of DNA damage, the class of mutations expected from tha t type of damage was reduced.