A mutable X{sup Z} chromosome isolated from a natural population of Drosophila melanogaster

In 1986, a mutable X{sup Z} 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{sup {minus}4} and were probably postmeiotic. Cytological analysis showed that two types of inversions occurred independently in X{sup Z} chromosome. Specific features of this chromosome are hypermutability of the white locus (the mutation rate was approximately 10{sup {minus}3}) and a hot spot for chromosomal rearrangements in the terminal segment of the X chromosome. 9 refs., 2 figs., 2 tabs.