title: The major components of the mouse and human genomes. 1. Preparation, basic properties and compositional heterogeneity.
abstract: Main-band DNA from mammals and birds can be resolved by density gradient centrifugation techniques into three or four families of fragments of different dG + dC contents. These major DNA components are similar in their buoyant densities and relative amounts in all species tested and are observed in DNA preparations ranging in Mr from 2 X 10(6) to over 200 X 10(6). In the present work, the four major components of mouse and human DNAs were prepared and characterized in several basic properties: relative amounts, dG + dC contents, buoyant densities and compositional heterogeneity. The results obtained lead to the following conclusions: (a) the major DNA components of mouse and man form at least 85% and possibly the totality of the main bands of these DNAs; (b) they have very low compositional heterogeneities over a wide molecular weight range; (c) they derive from very large chromosomal DNA segments of fairly homogeneous base composition, for which the name 'isochores' is proposed. A comparison of the compositional heterogeneity of main-band DNAs from warm-blooded and cold-blooded vertebrates confirms our previous conclusion that these DNAs are characterized by a different sequence organization.
mesh_terms: D000818:Animals; D001482:Base Composition; D004247:DNA / Q000032:analysis*; D003854:Deoxyribonucleotides / Q000032:analysis; D005260:Female; D005796:Genes; D006801:Humans; D007231:Infant, Newborn; D051379:Mice; D008807:Mice, Inbred BALB C; D008970:Molecular Weight; D010920:Placenta / Q000032:analysis; D011247:Pregnancy; D013045:Species Specificity; D013950:Thymus Gland / Q000032:analysis
chemical_list: D003854:Deoxyribonucleotides; D004247:DNA