[Mitotic recombination in cleavage divisions of Drosophila melanogaster. IV. Effect induced by radiation in female parents].

The premutational changes induced by X-irradiation (3 kr or 1 kr) in X-chromosomes of female gametes gave rise to mitotic recombination between irradiated female X-chromosomes and non-irradiated male X-chromosomes in early cleavage nuclei of F1 daughters. Most of the recombinants were non-mosaic females. It can be concluded from the analysis of their phenotypes as well as their offsprings that all nuclei of somatic and germinal tissues of these females were descendants of one from the four first cleavage nuclei (the recombinant one). There were differences in rates and in patterns of recombination between experiments with different stocks. The recombination induced by treatment of female parents usually occurred in the proximal part of X-chromosomes.