Abstract
Sequences homologous to the oncogene sequences of acute RNA tumor viruses have been shown to be highly conserved within vertebrates. In the present work, eight different oncogene DNA sequences have been used as probes to search for homologous sequences in the DNA of organisms of other phyla. Five of these probes hybridized to the DNA of Drosophila melanogaster. Abelson leukemia virus probe detected a single homologous DNA fragment in Drosophila DNA. In contrast, probes prepared from the genomes of Harvey, avian, and feline sarcoma viruses and avian myelocytomatosis virus hybridized with multiple homologous sequences in Drosophila DNA. The identification of sequences homologous to vertebrate oncogenes in invertebrates demonstrates both a high degree of conservation of these genes and a wide distribution among divergent species. It seems likely that sequences homologous to vertebrate oncogenes play a crucial role in metazoan metabolism.