title: On the heterogeneity of the slow reassociating ("unique") DNA.
abstract: The slow reassociating fraction of mouse DNA ("unique DNA"), when allowed to reassociate in 0.14 M sodoum phosphate buffer at 50 degrees C showed a biphasic melting curve with a transition at 78--80 degrees C. On the basis of this feature, the slow reassociating DNA was separated preparatively into two fractions: "unique DNA" I and II. Their duplexes showed differences with respect to thermal stability, S1 nuclease resistance and rate of reassociation. About one third of the sequences in each fraction were fraction-specific. The conclusion was drawn that for "unique DNA" I these should be the low repetitive or single copy related sequences (multigene families) and for "unique DNA" II--the unrelated single copy sequences or recent families of low repetitive not yet diverged sequences.
mesh_terms: D000818:Animals; D001483:Base Sequence; D002286:Carcinoma, Ehrlich Tumor / Q000378:metabolism; D004247:DNA / Q000302:isolation & purification / Q000378:metabolism*; D004261:DNA Replication; D006358:Hot Temperature; D007700:Kinetics; D008099:Liver / Q000378:metabolism; D051379:Mice; D009693:Nucleic Acid Hybridization; D009695:Nucleic Acid Renaturation; D014461:Ultracentrifugation
chemical_list: D004247:DNA