MUTATIONAL SPECTRA OF PRODUCTS OF INCOMPLETE COMBUSTION AND PYROLYSIS

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Based on recent progress in our ability to amplify mutant DNA sequences by high fidelity polymerase chain reaction and to separate mutant and wild type DNA sequences using denaturing gradient electrophoresis, we propose three separate efforts, each necessary to the intended use of this new technology to study the rate of combustion effluents in mutation in humans. First, we need to understand the relationship between existing cellular modes of analysis of mutation in human cell samples and our proposed molecular mode. At present, mutants are enumerated as 6-thioguanine resistant cells, growing as colonies. These mutants have little or not activity for the enzyme hypoxanthine phosphoribosyl transferase (hpt). We have developed an approach which examines point mutations at the DNA sequence level in one or a few exons of hprt. These independent modes reveal partially overlapping sets of mutations, and their relationship requires careful definition. We propose to use the mutagens fluoranthene, cyclopenta(c,d)pyrene and benzo(alpha)pyrene in this characterization effort. Although not a major mutagen in incomplete combustion effluents, benzo(alpha)pyrene's mutational spectrum has been studied in bacteria, and our effort will permit an important human cell/bacterial comparison. Secondly and thirdly, we are combining with Projects C-1, C-2 and D-3 to study the quantitative dose and time dependence of mutation in human cells and mutation and tumor formation in mouse tissue. These studies will result in understanding of the relationships in time among protein adducts, DNA adducts and mutation after exposures to fluoranthene, cyclopenta(c,d)pyrene, benzo(alpha)pyrene and important pyrolysis products as shall be determined by research in Projects A-1,-2,-3,-4, B and D-1,-2, and -3.