ABSTRACT
Survival of a diploid and a haploid wild type and a radiation-sensitive rad52-mutant was investigated after exposure to accelerated ions in the presence or absence of oxygen. Ar, Kr, Xe, Sm, Pb and U ions were used with specific energies between 0.3 and 12 MeV/u. The results demonstrate that the oxygen enhancement ratios (o.e.r.) do not only depend on LET or Z*2/beta 2 but even more so on ion specific energy. The o.e.r.s are always higher with greater E/m values pointing to the importance of delta-electron action.
Subject(s)
Oxygen/physiology , Saccharomyces cerevisiae/radiation effects , Cell Survival/radiation effects , Diploidy , Energy Transfer , Haploidy , Ions , Mutation , Particle AcceleratorsABSTRACT
The induction of forward mutations (resistance to canavanine) by heavy ion bombardment was investigated in wild type haploid yeast Saccharomyces cerevisiae. Accelerated ions of argon, titanium, nickel, krypton, xenon, lead and uranium with specific energies between 1.7 and 9.25 MeV/u were obtained from the UNILAC machine at the Gesellschaft für Schwerionenforschung, Darmstadt/Germany. LET-values ranged from 1200 to about 15 000 keV/microns. There was no unequivocal dependence of mutation induction cross section on either LET or Z*2/beta 2, but also a prominent influence of ion specific energy. This is explained by the action of long-ranging delta-electrons.
Subject(s)
Canavanine/pharmacology , Mutation , Saccharomyces cerevisiae/radiation effects , Ions , Particle Accelerators , Radiation Genetics , Saccharomyces cerevisiae/drug effectsABSTRACT
The ICRU recommends various methods for the energy calibration of electron accelerators in medical use. A simple method, so far rarely used, is based on the Cerenkov effect in gases. The method is described and its practical application discussed. Corrections and error effects on the energy determination are investigated in detail.
