title: Mechanisms for chromosomal aberrations in mammalian cells.
abstract: Experimental evidence is presented for the involvement of DNA double-strand breaks in the formation of radiation-induced chromosomal aberrations. When X-irradiated cells were post-treated with single-strand specific Neurospora crassa endonuclease (NE), the frequencies of all classes of aberration increased by about a factor 2. Under these conditions, the frequencies of DNA double-strand breaks induced by X-rays (as determined by neutral sucrose-gradient centrifugation), also increased by a factor of 2. The frequency of chromosomal aberrations induced by fast neutrons (which predominantly induce DNA double-strand breaks) was not influenced by post-treatment with NE. Inhibition of poly(ADP-ribose) polymerase, an enzyme that uses DNA with double-strand breaks as an optimal template, by 3-aminobenzamide also increased the frequencies of X-ray-induced chromosomal aberrations, which supports the idea that DNA double-strand breaks are important lesions for the production of chromosomal aberrations induced by ionizing radiation.
mesh_terms: D000818:Animals; D016590:Aphidicolin; D002869:Chromosome Aberrations; D002875:Chromosomes / Q000528:radiation effects*; D004247:DNA / Q000528:radiation effects; D004257:DNA Polymerase II / Q000037:antagonists & inhibitors; D004260:DNA Repair; D004261:DNA Replication / Q000187:drug effects / Q000528:radiation effects; D004224:Diterpenes / Q000494:pharmacology; D004720:Endonucleases / Q000378:metabolism; D006801:Humans; D008214:Lymphocytes / Q000528:radiation effects; D009492:Neurospora crassa / Q000201:enzymology; D011065:Poly(ADP-ribose) Polymerases / Q000528:radiation effects
chemical_list: D004224:Diterpenes; D016590:Aphidicolin; D004247:DNA; D011065:Poly(ADP-ribose) Polymerases; D004257:DNA Polymerase II; D004720:Endonucleases