HIGH-FREQUENCY OF MUTAGEN-INDUCED CHROMATID EXCHANGES AT INTERSTITIAL TELOMERE-LIKE DNA-SEQUENCE BLOCKS OF CHINESE-HAMSTER CELLS

Interstitial telomere-like DNA sequence arrays of Chinese hamster Don cells were delineated by fluorescence in situ hybridization in quadriradial and triradial chromosome configurations induced by X-rays, mitomycin C and teniposide (VM-26). Around 40% of the scored exchanges involved a telomeric-like block of sequences at a rearrangement site. This frequency was independent of the DNA-damaging agent, and the result suggests a general recombinogenic capacity of interstitial telomere-like DNA sequence repeats that, at least in the case of the agents employed, seems not to be related to the initial mechanism of DNA damage.