Mutation induction in bacteria after heavy ion irradiation
- Ceskoslovenska Akademie Ved, Brno (Czechoslovakia)
From a compilation of experimental data on the mutagenic effects of heavy ions in bacteria, main conclusions have been drawn as follows: (1) The mutagenic efficacy of heavy ions in bacteria depends on physical and biological variables. Physical variables are the radiation dose, energy and charge of the ion; the biological variables are the bacterial strain, the repair genotype of bacteria, and the endpoint investigated (type of mutation, induction of enzymes related to mutagenesis); (2) The responses on dose or fluence are mainly linear or linear quadratic. The quadratic component, if found for low LET radiation, is gradually reduced with increasing LET; (3) At low values of Z and LET the cross section of mutation induction sigma m (as well as SOS response, sigma sos and lambda phage induction), sigma lambda versus LET curves can be quite consistently described by a common function which increases up to approximately 100 keV/mu m. For higher LET values, the sigma(m) versus LET curves show the so-called `hooks` observed also for other endpoints; (4) For light ions (Z is less than or equal to 4), the cross sections mostly decrease with increasing ion energy, which is probably related to the decrease of the specific energy departed by the ion inside the sensitive volume (cell). For ions in the range of Z = 10, sigma(m) is nearly independent on the ion energy. For heavier ions (Z is greater than or equal to 16), sigma(m) increases with the energy up to a maximum or saturation around 10 MeV/u. The increment becomes steeper with increasing atomic number of the ion. It correlates with the increasing track radius of the heavy ion; (5) The mutagenic efficiency per lethal event changes slightly with ion energy, if Z is small indicating a rough correlation between cellular lethality and mutation induction, only.
- Research Organization:
- National Aeronautics and Space Administration, Moffett Field, CA (United States). Ames Research Center
- OSTI ID:
- 121783
- Report Number(s):
- N-95-32719; NASA-TM-110655; NAS-1.15:110655; CONF-9410388-; TRN: 9532727
- Resource Relation:
- Conference: 12. joint NASA/DARA-DLR life sciences program working group meeting, Moffett Field, CA (United States), 26-27 Oct 1994; Other Information: PBD: 1994; Related Information: Is Part Of Minutes of the 12th Joint NASA/DARA-DLR Life Sciences Program Working Group Meeting; White, R.J.; PB: 234 p.
- Country of Publication:
- United States
- Language:
- English
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