FLUORESCENCE IN-SITU HYBRIDIZATION DETECTION OF CHROMOSOMAL-ABERRATIONS IN HUMAN-LYMPHOCYTES - APPLICABILITY TO BIOLOGICAL DOSIMETRY

Human lymphocytes in Go have been irradiated with X-ray doses from 0 t o 40 Gy. Metaphase chromosomes 2, 3 and 5 and all centromeres were pai nted using fluorescence in situ hybridization (FISH) probe libraries. Dicentrics, centric rings and acentrics in the whole genome as well as translocations involving the painted chromosomes were recorded. The t ranslocations were subdivided as complete or incomplete. Interstitial insertions and inversions were also noted. The observations were also recorded according to the Protocol for Aberration Identification and N omenclature Terminology (PAINT) system of scoring. Given that the pain ted chromosomes comprise 20.4% of the genome it was found that the yie ld of bicoloured dicentrics was consistent with the yield of dicentric s in the whole genome. The yield of radiation-induced translocations w as not significantly higher than that of bicoloured dicentrics. Of the translocations, 60% were complete and it was concluded that the major ity of dicentrics and translocations are complete exchanges. Chromosom e 5 took part in exchanges marginally more commonly than its length su ggests, but it is not known if this is a property of the chromosome or whether it is a donor-dependent observation. The PAINT system of reco rding rearrangements was examined and the suggested numerical interpre tation of this nomenclature was considered to be unsuitable for use in the estimation of dose for cases of accidental overexposure.