The DNA Components of the Chicken Genome

Abstract

The organization of the chicken genome was investigated by centrifuging chicken DNA (Mr [molecular ratio] = 57 .times. 106) in preparative Cs2SO4/Ag+ and Cs2SO4/BAMD [3,6-bis(acetato-mercurimethyl)dioxane] density gradients. An analysis by CsCl density gradient of the DNA fractions obtained from the preparative experiments revealed that 88% of the genome is made up of 4 DNA components, characterized by buoyant densities of 1.699, 1.7025, 1.7045 and 1.708 g/cm3, representing 39, 25 and 9%, respectively, of the total DNA. The remaining 12% of the genome is formed by 7 minor and/or satellite components. The distribution of the ovalbumin gene in a Cs2CO4/BAMD density gradient, as tested with a cloned c[complementary]DNA probe, coincides with the distribution of the 1.7025-g/cm3 component. The DNA regions flanking the ovalbumin gene are evidently homogeneous in base composition over long distances and the gene is located on a DNA segment belonging to the 1.7025-g/cm3 component.