科研之友
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摘要
In a similar way to high-dose exposures to low-LET radiations, cells show difficulties reaching mitosis after high-LET radiation exposure. For this reason, techniques have been proposed that are able to analyze chromosome aberrations in interphase by prematurely condensing the chromosomes (PCC-techniques). Few dose-effect curves for high-LET radiation types have been reported, and none for -particles. The aim of this study was to evaluate, by chemically-induced PCC, the chromosome aberrations induced by several doses of -particles. Monolayers of peripheral lymphocytes were exposed to an -source of Americium-241 with a mean energy entering the cells of 2.7MeV. Lymphocytes were exposed to 10 doses, from 0-2.5Gy, and then cultured for 48h. Colcemid and Calyculin-A were added at 24 and 1h before harvesting, respectively. During microscope analysis, chromosome rings and extra chromosome pieces were scored in G2/M-PCC and M cells, while dicentric chromosomes were only scored in M cells. As the dose increased, fewer cells were able to reach mitosis and the proportion of G2/M-PCC cells increased. Chromosome rings were hardly observed in M cells when compared to G2/M-PCC cells. Extra fragments were more frequent than rings in both G2/M-PCC and M cells, but with lower frequencies than in G2/M-PCC cells. The distribution of dicentrics and extra fragments showed a clear overdispersion; this was not so evident for rings. The dose-effect curves obtained fitted very well to a linear model. Damaged cells after -particle irradiation show more difficulties in reaching mitosis than cells exposed to -rays. After -particle irradiation the frequency of all the chromosome aberrations considered increased linearly with the dose, and -particles clearly produced more dicentrics and extra chromosome pieces with respect to -rays. After -particle exposure, the existence of extra chromosome fragments in PCC cells seems to be a good candidate for use as a biomarker for dose assessment. However, the observed frequencies of different types of chromosomal aberrations could be influenced by some methodological aspects; for this reason, and in order to avoid possible methodological bias, standardization of the technique will be desirable.
- 出版日期2016
