Frequencies of Complex Chromosome Exchange Aberrations Induced by238Pu α-particles and Detected by Fluorescencein SituHybridization Using Single Chromosome-specific Probes

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Abstract
We undertook an analysis of chromosome-type exchange aberrations induced by α-particles using fluorescence in situ hybridization (FISH) with whole chromosome-specific probes for human chromosomes 1 or 4, together with a pan-centromeric probe. Contact-inhibited primary human fibroblasts (in G1) were irradiated with 0·41–1·00 Gy 238Pu α-particles and aberrations were analysed at the next mitosis following a single chromosome paint. Exchange and aberration painting patterns were classified according to Savage and Simpson (1994a). Of exchange aberrations, 38–47% were found to be complex derived, i.e. resulting from three or more breaks in two or more chromosomes, and the variation with dose was minimal. The class of complex aberrations most frequently observed were insertions, derived from a minimum of three breaks in two chromosomes. There was also an elevated frequency of rings. The high level of complex aberrations observed after α-particle irradiation indicates that, when chromosome domains are traversed by high linear energy transfer α-particle tracks, there is an enhanced probability of production of multiple localized double-strand breaks leading to more complicated interactions.