The relative biological effectiveness of accelerated carbon ions with different LET for inducing mitotic crossing over and intragenic reversion of the white-ivory allele in Drosophila larvae.
OBJECTIVE
To evaluate the relative biological effectiveness (RBE) of accelerated carbon ions generated with a synchrotron for inducing mutations as a function of linear energy transfer (LET), using the loss of heterozygosity for wing-hair mutations and the reversion of the mutant white-ivory eye-colour in Drosophila melanogaster.


METHODS
The measurements were made using a combined mutation assay system so that induced mutant wing-hair clones as well as revertant eye-colour clones can be detected simultaneously in the same fly. Larvae were irradiated at the age of 72+/-6 h post-oviposition with X-rays or carbon ions with LET values of 13, 60 and 95 keV/microm.


RESULTS
The RBE of carbon ions for producing wing-hair mosaic spots increased with increasing LET values. The RBE for the induction of eye-colour mutants did not change with LET. The estimated RBE values were found to be in the range 2 to 6.5 for the wing-hair and nearly unity for the eye-colour mosaic spot mutations.


CONCLUSIONS
RBE-LET relationships were obtained for the induction of wing-hair and eye-colour mosaic spots. These relationships suggest that more complex types of DNA damage, such as nonrejoinable strand breaks that increase with LET, may be responsible for inducing the wing-hair mutation, while more simple forms of molecular damage induce reversion in the white-ivory allele.
Department of Genetics, School of Medicine, Nagasaki University, Japan. isao@net.nagasaki-u.ac.jp
I
I
Yoshikawa
T
T
Takatsuji
M
M
Hoshi
J
J
Takada
T
T
Kanai
Y
Y
Furusawa
H
H
Nikjoo
M
M
Ikenaga
D000818:Animals; D002244:Carbon / Q000494:pharmacology; D004249:DNA Damage / Q000528:radiation effects; D004330:Drosophila / Q000196:embryology / Q000528:radiation effects*; D017344:Genes, Insect / Q000528:radiation effects*; D018499:Linear Energy Transfer / Q000235:genetics*; D019656:Loss of Heterozygosity / Q000528:radiation effects; D008938:Mitosis / Q000528:radiation effects*; D009154:Mutation / Q000235:genetics / Q000528:radiation effects; D011839:Radiation, Ionizing; D011874:Radiometry; D012062:Relative Biological Effectiveness; D014921:Wings, Animal / Q000528:radiation effects; D014965:X-Rays / Q000009:adverse effects
D002244:Carbon