Genetic control of chromosome breakage and rejoining in Drosophila melanogaster: spontaneous chromosome aberrations in X-linked mutants defective in DNA metabolism.

Abstract

Eight X-linked recombination-defective meiotic mutants (representing 5 loci) and 12 X-linked mutagen-sensitive mutants (representing 7 loci) of D. melanogaster were examined cytologically in neuroblast metaphases for their effects on the frequencies and types of spontaneous chromosome aberrations. Twelve mutants, representing 5 loci, significantly increase the frequency of chromosomal aberrations. The mutants at these 5 loci differ markedly both in the types of abberrations produced and the localization of their effects along the chromosome. The mutants can be assigned to 4 groups: mutants producing almost exclusively chromatid breaks in both euchromatin and heterochromatin; mutants producing chromatid and isochromatid breaks in both euchromatin and heterochromatin; mutants producing chromatid and isochromatid breaks primarily in euchromatin, and mutants producing chromatid and isochromatid breaks clustered in the heterochromatin.