MITOTIC AND MEIOTIC DETECTION OF RADIATION-INDUCED TRANSLOCATIONS IN MOUSE STEM-CELL SPERMATOGONIA USING FLUORESCENCE IN-SITU HYBRIDIZATION

The efficiency of two methods of detection of translocations induced i n mouse stem cell spermatogonia by X-ray doses of 2, 5 and 7 Gy was co mpared: classical multivalent analysis at diakinesis-metaphase I of me iosis and observation via fluorescence in situ hybridization analysis of mitotic or meiotic stages. Specific DNA libraries for chromosomes 1 , 11 and 13 were used. The results obtained indicate that (a) chromoso mes 1, 11 and 13 are more involved in multivalent formation than expec ted on the basis of DNA content and (b) if the mitotic FISH analysis d ata are corrected for the observed over-representation, the frequencie s of induced translocations are similar to those recorded in the class ical multivalent studies, suggesting equal scoring efficiencies in bot h systems.