Characteristics of homologous and heterologous DNA-RNA hybrids from unfertilized and fertilized eggs of houseflies, Musca domestica

Abstract

DNA and 14C-labelled RNA were isolated from fertilized and unfertilized eggs of houseflies ( Musca domestica). The two forms of nucleic acid were obtained from newly oviposited eggs and from eggs which had been incubated for 6 hours at 37°C., corresponding to the late embryonic developmental period. RNA-denatured DNA hybrids were prepared by hybridization in solution and with the DNA immobilized on membrane filters. The degree of hybridization of homologous and heterologous forms was determined by assaying the 14C-labelled RNA incorporated into the RNA-DNA hybrids. When the hybrids were formed by homologous RNA-DNA the degrees of hybridization of the forms from newly oviposited eggs and from incubated eggs were similar. A small decrease of doubtful significance was noted when heterologous hybrids were prepared from the nucleic acids of newly oviposited fertilized and unfertilized eggs. However, when heterologous hybrids were prepared from newly oviposited unfertile eggs and incubated fertile eggs, the degree of hybridization was only about 75 per cent of that found with homologous hybrids. When the hybridization involved RNA or DNA from newly oviposited fertile eggs and DNA or RNA from incubated fertile eggs, the hybridization was about 85 per cent of that for homologous hybrids.