Mutagenesis, Vol. 14, No. 3, 283-286,
May 1999
© 1999 UK Environmental Mutagen Society/Oxford University Press
Comparison of AluI-induced frequencies of dicentrics and translocations in human lymphocytes by chromosome painting
1 MGC, Department of Radiation Genetics and Chemical Mutagenesis, Leiden University Medical Centre, Leiden, The Netherlands, 2 Division of Human Cytogenetics and Quantitative Microscopy, Instituto de Investigaciones Biológicas Clemente Estable, Montevideo, Uruguay, 3 Department of Genetics, University of Essen, Essen, Germany and 4 J.A.Cohen Institute of Radiopathology and Radiation Protection, Inter-University Institute, Leiden, The Netherlands
It has been shown repeatedly that following irradiation of human lymphocytes in the G0 stage, more translocations are induced than dicentrics. To check the role of DNA double-strand breaks (DSB) alone for the induction of symmetrical and asymmetrical chromosome aberrations, the frequencies of induced exchange aberrations by the restriction enzyme AluI were analyzed. The enzyme was introduced into cells using the pellet pipetting technique. Frequencies of induced translocations and dicentrics were determined using a chromosome painting assay with chromosome-specific DNA libraries for chromosomes 1, 4 and X (representing 16.8% of the human genome). The number of translocations detected was ~3-fold higher than the number of dicentrics, indicating that the increased frequency of translocations compared with dicentrics found in irradiated human lymphocytes does not result from DNA lesions other than DSB but from differential processing of DSB.
5 To whom correspondence should be addressed. Tel: +598 2 487 16 16; Fax: +598 2 487 55 48; Email. wlopez{at}iibce.edu.uy