title: Loss of the normal N-ras allele in a mouse thymic lymphoma induced by a chemical carcinogen.
abstract: Young mice injected with the carcinogen N-nitroso-N-methylurea develop thymic lymphomas 2-4 months later. We previously have shown that these tumors frequently contain an activated N-ras gene that can transform rodent fibroblasts in vitro. We report here the intron/exon structure of such an activated N-ras gene and the sequence of its four coding exons. A single nucleotide change is responsible for the transforming alteration, a C----A transversion in the first base of codon 61. Through the use of synthetic oligonucleotides as hybridization probes, we show that this tumor lacks the normal allele of the N-ras gene. The implications of this finding for oncogene dominance are discussed.
mesh_terms: D000483:Alleles; D000818:Animals; D001483:Base Sequence; D001921:Brain / Q000502:physiology; D002874:Chromosome Mapping; D005799:Genes, Dominant; D008223:Lymphoma / Q000139:chemically induced / Q000235:genetics*; D008770:Methylnitrosourea; D051379:Mice; D009154:Mutation; D011519:Proto-Oncogenes; D013953:Thymus Neoplasms / Q000139:chemically induced / Q000235:genetics*
chemical_list: D008770:Methylnitrosourea