Abstract
In 1986, a mutable XZ-chromosome, in which mutation at genes yellow, white, and singed were recorded, was isolated from a natural population of Drosophila melanogaster from Zaporozh'e. Visible mutations in the region garnet-forked were also detected. Mutations appeared at a rate of about 10(-4) and were probably postmeiotic. Cytological analysis showed that two types of inversions occurred independently in XZ-chromosome. Specific features of this chromosome are hypermutability of the white locus (the mutation rate was approximately 10(-3) and a hot spot for chromosomal rearrangements in the terminal segment of the X-chromosome.
