Suppression of ribosomal RNA genes in Drosophila melanogaster

Abstract

The rDNA of five Y chromosome mutants was examined with respect to their insert free (In−) repeat type multiplicity. The In− repeat number of each mutant was correlated with its hemizygous bobbed phenotype and additivity with an X NO bobbed (bb) mutant. Four of these mutants showed a direct relationship between their In− frequency, hemizygous bb phenotype and additivity tests. A fifth mutant, bb1–4, had a sufficient number of In− repeats to ensure viability to the late pupal stage and show additivity; however, the In− repeats genetically behaved as a complete rDNA deletion. Possible mechanisms resulting in the suppression of the bb1–4 In− repeats are discussed. © 1984, Cambridge University Press. All rights reserved.