title: On the origin of chromosomal aberrations in human peripheral lymphocytes in vitro. I. Experiments with Neurospora endonuclease and polyethylene glycol.
abstract: Post-treatment of mutagen-treated human peripheral lymphocytes with a single-strand specific endonuclease from Neurospora crassa leads to a significant elevation of the rate of structural chromosomal aberrations. Our results indicate that DNA double-strand breaks (DSB) are ultimate lesions for the formation of chromosomal aberrations in the G1 and G2 phase of the cell cycle and probably also in the S-phase. Post-treatment of X-irradiated G2 cells with polyethylene glycol (PEG) leads to an elevation of the frequencies of chromatid type aberrations. This result is taken as an indication that nucleases from PEG-damaged lysosomes transform lesions in X-ray damaged chromosomes to DSB. With respect to the origin of chromosomal aberrations, our results are in favour of the breakage and reunion hypothesis of K. Sax , and not of Revell 's exchange hypothesis.
mesh_terms: D002453:Cell Cycle; D002478:Cells, Cultured; D002869:Chromosome Aberrations / Q000187:drug effects* / Q000528:radiation effects; D004720:Endonucleases / Q000494:pharmacology*; D004852:Epoxy Compounds / Q000494:pharmacology; D006801:Humans; D008214:Lymphocytes / Q000187:drug effects / Q000528:radiation effects / Q000648:ultrastructure; D008957:Models, Genetic; D009492:Neurospora crassa / Q000201:enzymology; D011092:Polyethylene Glycols / Q000494:pharmacology*; D014228:Triaziquone / Q000494:pharmacology
chemical_list: D004852:Epoxy Compounds; D011092:Polyethylene Glycols; C007366:diepoxybutane; D004720:Endonucleases; D014228:Triaziquone