Analysis of spontaneous and bleomycin-induced chromosome damage in peripheral lymphocytes of long-haul aircrew members from Argentina.

Spontaneous and bleomycin (BLM)-induced chromosomal aberrations in G0 and G2 stages of the cell cycle have been analyzed in peripheral lymphocytes of 21 long-haul aircrew members from Argentina in order to assess BLM-induced clastogenesis as a first approach to determine the DNA repair capacity and thereby the susceptibility to environmental cancers in aircrew. The possibility that occupational exposure of flight personnel to cosmic radiation can induce an adaptive response in their peripheral lymphocytes that can be detected by a subsequent in vitro treatment with BLM was also investigated. For comparison, aberrations were also scored in the lymphocytes of 15 healthy volunteers matched by age, health, sex, drinking and smoking habits to the flight personnel group. Aircrew exhibited a higher frequency of spontaneous dicentrics and ring chromosomes than the control population (p<0.05). BLM sensitivity test showed that aircrew and controls are equally sensitive to BLM G2 clastogenic effects, since both groups exhibited a similar frequency of chromatid breaks per cell (p>0.05). However, the aircrew sampled population was almost two times more sensitive to BLM G0 clastogenic effects than controls (p<0.05). Therefore, our data suggest that chronic exposure of aircrew to cosmic radiation increases the in vitro chromosomal sensitivity of their peripheral lymphocytes to BLM (at least in the G0 stage of the cell cycle), and that occupational exposure of flight personnel to cosmic radiation does not induce an adaptive response to this radiomimetic compound. Our results justify further studies aimed at determine if those aircrew members hypersensitive to BLM are more prone to develop environmental cancer than BLM-insensitive individuals.

A comparative analysis of bleomycin-induced incomplete chromosome elements in two mammalian cell lines using a telomeric PNA probe.

Fluorescence in situ hybridization (FISH) with a telomeric peptide nucleic acid probe was employed to analyze the induction of incomplete chromosome elements (ICE; i.e., incomplete chromosomes and terminal fragments) by bleomycin (BLM) in two mammalian cell lines. Chinese hamster embryo cells (CHE cell line, average 2n = 23) and domestic rabbit cells (CPC cell line, average 2n = 44) were treated with 2.5 micro g/ml BLM; after 18 hr of incubation, first-division metaphases were stained with the telomeric probe, and ICE and other unstable chromosomal aberrations were scored. BLM induced ICE, dicentrics, and interstitial acentric fragments in CHE cells, but only ICE in CPC cells. About 50% of the metaphases in BLM-treated CHE cells contained one or more pairs of ICE, while only 20% of treated CPC cells contained ICE. Almost 100% of the BLM-induced ICE in both cell lines consisted of pairs formed by an incomplete chromosome and a terminal fragment. Our results confirm that ICE are the most frequent type of unstable chromosomal aberration induced by BLM in mammalian cells. Moreover, the present study shows that an increase in the chromosome number does not necessarily result in an increase in the frequency of BLM-induced ICE. The results also show that the difference in the chromosomal sensitivity to BLM in CHE and CPC cells is due to differences in the absolute frequency but not in the pattern (i.e., type and proportion) of ICE.