Abstract
In order to explore the mechanism of electrophoretic mutation due to intragenic recombination at the Est-α locus of Drosophila virilis, some selected alleles were repeatedly used in cross experiments. Some genotypes of female heterozygotes could produce several mutants, whereas others generated no significant number of mutants. Moreover, the directional nature of mutant occurrence was also confirmed as seen in the previous studies (Tsuno 1981). When newly arisen mutants obtained in the previous study were used in cross experiments, no increase in mutation rate was observed. From these observations, it is suggested that the majority of the mutations is due to intragenic recombination within introns rather than gene conversion. Thus, a general model for the Est-α locus is proposed.
