Mutation and inactivation of cultured mammalian cells exposed to beams of accelerated heavy ions. II. Chinese hamster V79 cells.

Inactivation and mutation to thioguanine-resistance of V79 hamster cells were studied after irradiation with accelerated helium, boron or nitrogen ions covering a range of linear energy transfer from 28 to 470 keV micrometers-1. For all radiation qualities a dose-dependent increase in mutant frequency was found for doses giving surviving fractions greater than about 0.20. The effectiveness per unit dose for both inactivation and mutation induction increased with the linear energy transfer of the radiation to a maximum in the range 90-200 keV micrometer-1. However, the maximum mutagenic effectiveness relative to gamma-rays was about two or more times that for inactivation. It is suggested that a proportion of the radiation-induced mutants suffer extensive genetic damage, and that some forms of this damage may be induced with high efficiency by radiations of high linear energy transfer.