Spontaneous and ionizing radiation induced mutations involve large events when selecting for loss of an autosomal locus

Mitchell Turker, Kimberly A. Walker, C. Darrell Jennings, Isabel Mellon, Altaf Yusufji, Muneyasu Urano

Research output: Contribution to journalArticlepeer-review

17 Scopus citations


The mouse P19H22 embryonal carcinoma cell line contains two distinct chromosome 8 homologs, one derived from Mus musculus domesticus (M. domesticus) and the other derived from Mus musculus musculus (M. musculus). It also contains a deletion for the M. musculus aprt allele, which is located on chromosome 8. In this study, cells with spontaneous or induced aprt deficiencies were isolated from P19H22 and examined to determine the nature of the mutational events that had occurred. Ultraviolet radiation (UV), ethyl methanesulfonate (EMS), and two forms of ionizing radiation, 137Cs and 252Cf, were used for mutation induction. DNA preparations from the aprt deficient cells were initially screened with a Southern blot analysis and separated into two broad classes: those that had lost the M. domesticus aprt allele and those that had retained it. The overwhelming majority ( > 95%) of the spontaneous and ionizing radiation-induced mutants exhibited aprt gene loss, indicating that relatively large events had occurred and that homozygosity for the deleted region was not a lethal event. Loss of heterozygosity for syntenic markers was found to be a common event in cells exhibiting aprt gene loss. In contrast, a majority of the UV-induced mutants (61%) and a substantial minority of the EMS-induced mutants (38%) retained the aprt gene. A sequence analysis confirmed that base-pair substitutions were responsible for this class of mutation. Gene inactivation associated with hypermethylation of the promoter region was found to be a rare event and was not induced by any of the mutagenic agents tested. The results demonstrate the suitability of the P19H22 cell line for mutational studies, particularly those that are large in nature.

Original languageEnglish
Pages (from-to)97-105
Number of pages9
JournalMutation Research - Fundamental and Molecular Mechanisms of Mutagenesis
Issue number2
StatePublished - Jul 1995

Bibliographical note

Funding Information:
This work was supported by NIH grant CA56383 and a supplemental grant from NASA. We thank Nada Khattar for a critical reading of this manuscript and Dick Krycsio and Mary Kay Rayens for help with statistical analysis.


  • Aprt deficiency
  • Autosome loss
  • P19H22 mouse embryonal cell line

ASJC Scopus subject areas

  • Molecular Biology
  • Genetics
  • Health, Toxicology and Mutagenesis


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