Complexity of RNA in Eggs of DROSOPHILA MELANOGASTER and MUSCA DOMESTICA

Comparative measurements are presented of the sequence complexity of the RNA stored in the eggs of two dipteran flies, Musca domestica and Drosophila melanogaster. The genome of Musca is about five times the size of the Drosophila genome and contains about 3.6 times as much single-copy sequence. As shown earlier, the interspersion of repetitive and single-copy sequence is of the short-period form in Musca, and is of the long-period form in Drosophila. The egg RNA complexities were determined by hybridization of excess RNA with radioactively labeled single-copy DNA. Complexity is expressed as the length (in nucleotides) of diverse single-copy sequence represented in the RNA. The complexity of the RNA of the Musca egg is about 2.4 x 10⁷ nucleotides, and that of the Drosophila egg is about 1.2 x 10⁷ nucleotides. The RNA of the Musca egg is similar to or very slightly lower in complexity than that of other egg RNAs, e.g., those of Xenopus and sea urchin. Compared to all previously measured egg RNAs, Drosophila egg RNA is low in sequence complexity.