A MUTABLE X(Z)-CHROMOSOME ISOLATED FROM A NATURAL-POPULATION OF DROSOPHILA-MELANOGASTER

In 1986, a mutable X(Z)-chromosome, in which mutation at genes yellow, white, and singed were recorded, was isolated from a natural populati on of Drosophila melanogaster from Zaporozh'e. Visible mutations in th e region garnet-forked were also detected. Mutations appeared at a rat e of about 10(-4) and were probably postmeiotic. Cytological analysis showed that two types of inversions occurred independently in X(Z)-chr omosome. Specific features of this chromosome are hypermutability of t he white locus (the mutation rate was approximately 10(-3)) and a hot spot for chromosomal rearrangements in the terminal segment of the X-c hromosome.