Abstract
The restriction enzymes from H.influenzae have been used to study various eucaryotic DNAs. Fractions resistant to the action of these enzymes have been isolated from rat, mouse and calf DNAs. The method revealed the existence in rat of several components having the properties of satellite DNAs. Mouse DNA was shown to contain a new satellite of buoyant density 1. 704. Therefore, this appears to be a powerfull method for the isolation of "hidden" satellite DNAs. Calf satellite DNAs rho = 1.705 and rho = 1.723 were those resistant to the action of the restriction enzymes whilst satellite DNAs rho = 1.714 and rho = 1.710 gave fragments of discrete lengths, suggesting internal repeat units of 1 500 and 5 000 base pairs respectively.