Detection of structural chromosome damage in rat interphase cells using region-specific fluorescence in situ...

Cytogenetic analysis using fluorescence in situ hybridization (FISH) was employed to detect structural chromosome aberrations in interphase. We generated DNA probes specific for rat chromosome regions 1q11-12, 1q31-35 and 1q51-53 by microdissection and degenerate oligonucleotide-primed PCR. Targeted regions were labeled in unique colors by FISH. Abnormal cells were identified on the basis of alterations in the physical distance between the hybridization signals. To evaluate the ability of these probes to quantify chromosome aberrations in interphase, rats were acutely exposed whole-body to 0, 1, 2, 3 or 4 Gy of 137Cs gamma rays. Eight days later, peripheral blood, bone marrow, lung and pancreas were removed and hybridized with the probes. Multi-color FISH analysis showed dose-responsive frequencies of abnormal interphase nuclei in peripheral blood and bone marrow cells. In lung and pancreas, on the contrary, no increase in the frequency of the abnormal interphases was observed. However, chromosome damage was observed when primary lung cells, obtained from rats irradiated 8 days previously, were cultured for three days. Detection of rearranged signals after in vitro tissue culture was attributed to the movement of chromosome domains that accompanies mitosis. The use of region-specific painting probes appears useful for detecting structural chromosome damage in interphase cells of rat tissues, although further optimization is still needed to improve the method.