5.8 S and 2 S rDNA is located in the ‘transcribed spacer’ region between the 18 S and 26 S rRNA genes in Drosophila melanogaster

Abstract

In Drosophila melanogaster, two small RNA species are found hydrogen bonded to 26 S rRNA:5.8 S rRNA, approximately 125 nucleotides long, and 2 S rRNA, 30 nucleotides long [1]. Evidence from pulse-chase experiments shows that they arise as the result of post transcriptional processing of 26 S RNA, and that the corresponding cleavages occur in the cytoplasm after the central cleavage of the 26 S molecule which occurs in the nucleus [1]. These results do not define completely the architecture of the 26 S molecule and a number of different models remain possible (fig.1). If it is assumed, by analogy with Xenopus laevis [2] that 5.8 S rRNA is coded by a DNA region located between the genes for 18 S and 26 S rRNAs, then class (c) models can be excluded. The experiments reported here examine this question directly by hybridization of ³²P-1abelled 5.8 S and 2 S RNAs to cloned D. melanogaster rDNA fragments [3].