HPRT MUTATIONS IN V79 CHINESE-HAMSTER CELLS INDUCED BY ACCELERATED NI, AU AND PB IONS

Mutation induction by accelerated heavy ions to 6-TG resistance (HPRT system) in V79 Chinese hamster cells was investigated with Ni (6-630 M eV/u), Au (2.2, 8.7 MeV/u) and Pb ions (11.6-980 MeV/u) corresponding to a LET range between 180 and 12895 keV/mu m. Most experiments could only be performed once due to technical limitations using accelerator beam times. Survival curves were exponential, mutation induction curve s linear with fluence. From their slopes inactivation- and mutation-in duction cross-sections were derived. If they are plotted versus LET, s ingle, ion-specific curves are obtained. It is shown that other parame ters like ion energy and effective charge play an important role. In t he case of Au and Pb ions the cross-sections follow a common line, sin ce these ions have nearly the same atomic weight, so that they should have similar spatial ionization patterns in matter at the same energie s. Calculated RBEs were higher for mutation induction than for killing for all LETs.