Über Änderungen im Verlauf von Dosiseffektkurven und ihre Auswirkungen auf das Mutantenspektrum

Summary

Dose response curves of 4 somatic mutations ofEphestia kühniella were established for the dose-range between 100 and 1000r of X-rays after six hours of pretreatment in different temperatures (+3 and +35°C). The curves are non-linear and can be fitted by the equationy=ax ^b, werea is a constant, which is different for each mutant type, whileb is the same for all four mutants. The values ofa andb vary with the pre-irradiation-temperature. The exponentb is higher after a high temperature-treatment than after a low one. The differenceb ₃₅ ^o-b₃ ^o is the same for all mutants. The sensitivity of the mutation process (a) goes down after the warm treatment compared to the cold one. The direction of the change is the same for all mutants, but the difference between the treatments is proportionally higher in the less frequent types (ES 2 and ES 4) than in the more frequent mutants (ES 1 and ES 3). This leads to differences in the mutational spectrum, which — at certain doses — are as pronounced as to make the different mutant types show different reactions towards the same treatment (cold treatment, for example, yields more ES 2 and less ES 1 than a warm one at doses from about 500 r up to about 1300 r).

The investigations may serve as an example for the fact, that a change in the mutational spectrum does not necessarily imply a different reaction of the mutant types to the modifying agent, but that it can be brought about as well by an analogous change in the parameters of their dose effect curves.