MUTANT FREQUENCY AT THE HPRT-LOCUS AND IN MINISATELLITE SEQUENCES IN CHINESE-HAMSTER V79-CELLS IRRADIATED WITH LOW-ENERGY PROTONS (31-KEV MU-M) AND ULTRAVIOLET-LIGHT (254-NM)/

Ionizing radiations induce mutations which can be detected both in cod ing sequences (Hprt locus) by measuring the frequency of 6-thioguanine -resistant cells and in minisatellite sequences by DNA fingerprint ana lysis. We analyzed the effects of irradiation with low-energy protons (31 keV/mu m) and, for comparison, with ultraviolet light (254 nm), fo r which DNA damage and repair mechanisms are better understood, on cul tures of Chinese hamster V79 cells with the two methods mentioned abov e. The results indicate that the frequency of 6-thioguanine-resistant cells was increased significantly, although very differently, by both treatments. The analyses carried out by DNA fingerprinting with a mult ilocus DNA probe show that the level of induction in minisatellite seq uences was higher compared to those measured at the Hprt locus after p roton irradiation, but lower after treatment with ultraviolet light. ( C) 1997 by Radiation Research Society.