Isolation and characterization of mouse and guinea pig satellite deoxyribonucleic acids

Mouse and guinea pig satellite deoxyribonucleic acids have been isolated using Ag+-Cs2SO4 density gradient centrifugation. The complementary strands have been separated in preparative alkaline CsCl density gradients, or in neutral CsCl, after heat denaturation in the presence of formaldehyde. The satellite deoxyribonucleic acids and their complementary strands have been investigated in some of their physical properties (buoyant densities, melting tern-peratures, and denaturation-renaturation properties), and in their base composition. In contrast with the main deoxyribonucleic acids, the satellite deoxyribonucleic acids show buoyant densities and melting temperatures which are quite different from those expected on the basis of analytical data. The separated complementary strands of satellite deoxyribonucleic acids show base compositions which are very different from each other, particularly in the case of guinea pig satellite.