Franz G, Kunz W
Nature. 1981 Aug 13;292(5824):638-40. doi: 10.1038/292638a0.
The "bobbed' (bb) mutation in Drosophila is represented phenotypically by shortened and abnormally thin scutellar bristles and by delayed development. There is a direct correlation between bristle size and ribosomal RNA (rRNA) synthesis, and the bb mutation was at first explained as a deficiency of rRNA genes (rDNA). However, the bb phenotype can occur in Drosophila melanogaster and Drosophila hydei with high rDNA content, while phenotypically wild-type flies are known with few rRNA genes, suggesting that what matters is not the number of rRNA genes but their transcriptional activity. In D. melanogaster, it has recently emerged that rRNA genes interrupted by an intervening sequence are not transcribed. We now report that in D. hydei, the length of the scutellar bristle is directly proportional to the number of rRNA genes without this intervening sequence.
果蝇中的“截短”（bb）突变在表型上表现为小盾片刚毛缩短且异常纤细，以及发育延迟。刚毛大小与核糖体RNA（rRNA）合成之间存在直接关联，最初bb突变被解释为rRNA基因（rDNA）的缺失。然而，bb表型可出现在rDNA含量高的黑腹果蝇和海德氏果蝇中，而已知rRNA基因很少的果蝇在表型上却是野生型，这表明重要的不是rRNA基因的数量，而是它们的转录活性。在黑腹果蝇中，最近发现被间隔序列中断的rRNA基因不被转录。我们现在报告，在海德氏果蝇中，小盾片刚毛的长度与没有这种间隔序列的rRNA基因数量成正比。
