The objective of this research is to investigate the mechanisms by which ionizing radiaton-induced DNA damage results in mutations. We propose two general approaches. The first is to continue the work begun during the last grant period in which organic synthesis and recombinant DNA techniques were being used to construct viral and plasmid DNA molecules that contain, at specific genome sites, the known products of ionizing radiation damage (initially cis-5,6-dihydroxy-6-hydrothymine, thymine glycol). These structurally altered genomes will be introduced to the intracellular enivronment, where the radiation-induced lesions may cause mutation. Conceivably this will occur through misreplication or faulty repair of the structrually altered DNA. Finally, we shall characterize quantitatively and qualitatively the mutagenic changes induced in daughter DNA molecules, and attempt to establish formal rules that relate the structure of a lesion with its bioligical effects. Our second proposed approach to assessing the gentic effects of ionizing radiation will be to determine the pattern of mutation, or mutational spectrum, induced by radiation in a plasmid-based mutation assay we developed during the previous grant period. The noteworthy features of this plasmid-based assay are its ability to detect forward mutations, a positive selection for the mutant phenotype, and the fact that the target for mutagenesis is small, approximately 400 bp, making determination of mutational spectra by direct DNA sequencing a resonable objective.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA033821-06
Application #
3171599
Study Section
Radiation Study Section (RAD)
Project Start
1983-02-01
Project End
1990-01-31
Budget Start
1988-02-01
Budget End
1989-01-31
Support Year
6
Fiscal Year
1988
Total Cost
Indirect Cost
Name
Massachusetts Institute of Technology
Department
Type
Schools of Arts and Sciences
DUNS #
City
Cambridge
State
MA
Country
United States
Zip Code
02139
Wood, M L; Dizdaroglu, M; Gajewski, E et al. (1990) Mechanistic studies of ionizing radiation and oxidative mutagenesis: genetic effects of a single 8-hydroxyguanine (7-hydro-8-oxoguanine) residue inserted at a unique site in a viral genome. Biochemistry 29:7024-32
Essigmann, J M; Basu, A K; Loechler, E L (1989) Mutagenic specificity of alkylated and oxidized DNA bases as determined by site-specific mutagenesis. Ann Ist Super Sanita 25:155-61
Basu, A K; Loechler, E L; Leadon, S A et al. (1989) Genetic effects of thymine glycol: site-specific mutagenesis and molecular modeling studies. Proc Natl Acad Sci U S A 86:7677-81
Couto, L B; Chaudhuri, I; Donahue, B A et al. (1989) Separation of the SOS-dependent and SOS-independent components of alkylating-agent mutagenesis. J Bacteriol 171:4170-7
Lasko, D D; Basu, A K; Kadlubar, F F et al. (1987) A probe for the mutagenic activity of the carcinogen 4-aminobiphenyl: synthesis and characterization of an M13mp10 genome containing the major carcinogen-DNA adduct at a unique site. Biochemistry 26:3072-81
Essigmann, J M; Loechler, E L; Green, C L (1986) Genetic toxicology of O6 methylguanine. Prog Clin Biol Res 209A:433-40
Essigmann, J M; Loechler, E L; Green, C L (1986) Mutagenesis and repair of O6-substituted guanines. IARC Sci Publ :393-9
Essigmann, J M; Fowler, K W; Green, C L et al. (1985) Extrachromosomal probes for mutagenesis by carcinogens: studies on the mutagenic activity of O6-methylguanine built into a unique site in a viral genome. Environ Health Perspect 62:171-6
Rouet, P; Essigmann, J M (1985) Possible role for thymine glycol in the selective inhibition of DNA synthesis on oxidized DNA templates. Cancer Res 45:6113-8