Induced rates of mitotic crossing over and possible mitotic gene conversion per wing anlage cell in Drosophila melanogaster by X rays and fission neutrons.
As a model for chromosome aberrations, radiation-induced mitotic recombination of mwh and flr genes in Drosophila melanogaster strain (mwh +/+ flr) was quantitatively studied. Fission neutrons were five to six times more effective than X rays per unit dose in producing either crossover-mwh/flr twins and mwh singles-or flr singles, indicating that common processes are involved in the production of crossover and flr singles. The X-ray-induced rate/wing anlage cell/Gy for flr singles was 1 X 10(-5), whereas that of crossover was 2 x 10(-4); the former and the latter rate are of the same order of magnitude as those of gene conversion and crossover in yeast, respectively. Thus, we conclude that proximal-marker "flr" singles induced in the transheterozygote are gene convertants. Using the model based on yeast that recombination events result from repair of double-strand breaks or gaps, we propose that mitotic recombination in the fly is a secondary result of recombinational DNA repair. Evidence for recombinational misrepair in the fly is given. The relative ratio of radiation-induced mitotic crossover to spontaneous meiotic crossover is one order of magnitude higher in the fly than in yeast and humans.
Ayaki
T
T
Department of Genetics, Nagasaki University School of Medicine, Japan.
Fujikawa
K
K
Ryo
H
H
Itoh
T
T
Kondo
S
S
D000818:Animals; D002869:Chromosome Aberrations; D003434:Crossing Over, Genetic; D004249:DNA Damage; D004260:DNA Repair; D004331:Drosophila melanogaster / Q000033:anatomy & histology / Q000235:genetics* / Q000528:radiation effects; D005785:Gene Conversion; D006801:Humans; D008938:Mitosis; D008957:Models, Genetic; D009502:Neutrons; D011995:Recombination, Genetic; D015003:Yeasts / Q000235:genetics