title: Genetic analysis of XR-1 mutation in hamster and human hybrids.
abstract: We investigated the dominant/recessive nature of the XR-1 mutant locus in intraspecies Chinese hamster ovary (CHO) hybrids and interspecies hybrids with human cell lines that possess different radioresistances. The XR-1 cell is abnormally sensitive to killing by gamma rays in the G1 phase of the cell cycle, while late-S-phase cells have wild-type resistance. [3H]Thymidine selection was used to eliminate the resistant S-phase population. In both intraspecies and interspecies hybrids, the XR-1 mutation is recessive to the wild-type cell and is not influenced by differences in chromosome ploidy. Analysis of hybrids between human ataxia telangiectasia fibroblasts AT5BI and XR-1 cells revealed that they possess different genetic defects as they complemented each other in three of four hybrids tested. These data suggest that the XR-1 locus is evolutionarily conserved between hamster and human cells.
authors.affiliation: Wistar Institute of Anatomy and Biology, Philadelphia, Pennsylvania 19104.
authors.forename: A J
authors.initials: AJ
authors.lastname: Giaccia
authors.forename: E
authors.initials: E
authors.lastname: Richardson
authors.forename: N
authors.initials: N
authors.lastname: Denko
authors.forename: T D
authors.initials: TD
authors.lastname: Stamato
mesh_terms: D000818:Animals; D001260:Ataxia Telangiectasia / Q000235:genetics; D002470:Cell Survival; D006224:Cricetinae; D004260:DNA Repair / Q000528:radiation effects; D005720:Gamma Rays; D005799:Genes, Dominant; D005808:Genes, Recessive; D005816:Genetic Complementation Test; D006801:Humans; D006822:Hybrid Cells; D007399:Interphase / Q000528:radiation effects; D009154:Mutation; D011003:Ploidies; D011836:Radiation Tolerance