Regulation in rDNA-deficient Drosophila melanogaster

Bobbed mutants of Drosophila melanogaster were used to determine whether there is any functional compensation for deficiency in rDNA content. The rate of rRNA accumulation was measured in the testes of five bb mutants of different phenotypic severity and in a wild type strain. The different rates of rRNA accumulation were compared to the phenotype (macroscutellar bristle length) and found to have a direct correlation (as in Weinman, 1972). However, there was not a direct relationship between the rate of rRNA accumulation and rDNA content. It is concluded that there is regulation of rRNA accumulation in some mutants, but that the regulation cannot be considered to be a compensation for the lack of rDNA. These results are discussed relative to other observations on the regulation of RNA synthesis in Drosophila.