ANALYSIS OF RADIATION-INDUCED MICRONUCLEI IN 2-CELL HUMAN-HAMSTER EMBRYOS USING TELOMERIC AND CENTROMERIC FISH PROBES

Simultaneous, fluorescent in situ hybridization using a centromeric hu man alpha satellite DNA probe and a telomeric DNA probe was used to an alyze the chromosome content of micronuclei induced in two-cell human- hamster embryos by in vitro gamma-ray irradiation of human spermatozoa . In unirradiated samples, about 26% of micronuclei were centromere po sitive, indicating that both structural chromosome aberrations and num erical changes are involved in the spontaneous production of micronucl ei. After exposure of spermatozoa to radiation, a significant increase in the number of micronuclei was found. About 77% of induced micronuc lei contained only telomeric signals suggesting that they originated f rom acentric fragments. However, both centromere-positive and centrome re-negative micronuclei increased with radiation dose. These results a re consistent with the well known clastogenic effect of ionizing radia tion and with its weak aneugenic effect.