Somatic and germinal mutations can have a severe impact on the fitness of multicellular organisms and offspring. The ability to study the occurrence of mutations in higher organisms has been limited by available methods rendering it difficult to address important questions such a 1) kinetics of mutation induction in relation to organ specificity, 2) mutation induction during development, 3) systemic effect of somatic mutations of age-related degenerative diseases, and 4) tumor progression from pre-neoplastic to neoplastic growth in relation to genomic stability. PhiX174 with the well characterized am3 mutation is used as a transgene to evaluate substitutions at the A:T base pair. Using this system mutations that are fixed in the animal can be separated from the mutations that arise from ex vivo damage in the DNA. Most cells in neonatal mice will divide several times before the animal reaches adulthood. The mutational fixation of DNA damage requires at least semi-conservative DNA replications. A study is in progress to test if young animals are more effective in mutational fixation of DNA damage than adult animals. Mice hemizygous for the phiX insert were injected i.p. with 50 mg/kg of ENU. After treatment of 4-day-old animals with ENU the revertant frequency in the brain was significantly increased above control. In contrast there was no increase in the revertant frequency in the brain after treating adults with a similar dose of ENU. These studies will be expanded to include liver, spleen and testis from the same animals.

Agency
National Institute of Health (NIH)
Institute
National Institute of Environmental Health Sciences (NIEHS)
Type
Intramural Research (Z01)
Project #
1Z01ES065033-16
Application #
6432374
Study Section
(LT)
Project Start
Project End
Budget Start
Budget End
Support Year
16
Fiscal Year
2000
Total Cost
Indirect Cost
Name
U.S. National Inst of Environ Hlth Scis
Department
Type
DUNS #
City
State
Country
United States
Zip Code
Samet, Jonathan M; DeMarini, David M; Malling, Heinrich V (2004) Biomedicine. Do airborne particles induce heritable mutations? Science 304:971-2
Weaver, Robert P; Malling, Heinrich V (2003) The in vivo but not the in vitro am3 revertant frequencies increase linearly with increased ethylnitrosourea doses in spleen of mice transgenic for phiX174 am3, cs70 using the single burst assay. Mutat Res 534:1-13
Valentine, Carrie R; Montgomery, Beverly A; Miller, Scott G et al. (2002) Characterization of mutant spectra generated by a forward mutational assay for gene A of Phi X174 from ENU-treated transgenic mouse embryonic cell line PX-2. Environ Mol Mutagen 39:55-68
Cosentino, Lidia; Malling, Heinrich V; Heddle, John A (2002) Response of the phiX174 am3, cs70 transgene to acute and chronic ENU exposure: implications for protocol design. Mutat Res 518:113-21
Malling, H V; Delongchamp, R R (2001) Direct separation of in vivo and in vitro am3 revertants in transgenic mice carrying the phiX174 am3, cs70 vector. Environ Mol Mutagen 37:345-55
Delongchamp, R R; Valentine, C R; Malling, H V (2001) Estimation of the average burst size of Phix174 am3, cs70 for use in mutation assays with transgenic mice. Environ Mol Mutagen 37:356-60
Delongchamp, R R; Malling, H V; Chen, J B et al. (1999) An estimator of the mutant frequency in assays using transgenic animals. Mutat Res 440:101-8
Malling, H V (1999) Frederick J. de Serres: the years at the Research Triangle Park (1972-1995). Mutat Res 437:69-75
Malling, H V; Newbold, R R; Lewis, S et al. (1999) Mutagenesis of a single AT basepair in mice transgenic for PhiX174 am3, cs70. II. Brain. Mutat Res 444:85-95