Chromosomal localizations by in situ hybridization of the repetitious human DNA families and evidence of their satellite DNA equivalents.

Four of the five major repetitious human DNA families have been mapped by the in situ hybridization technique at their TOPT values. Two of the lighter density DNA families have autoradiographic grain patterns over heterochromatic chromosomal regions that resemble those of known satellite DNAs. The two heaviest density DNA families have autoradiographic grain patterns of middle repetitious DNAs, with all chromosomes showing labelling. Some evidence suggests that one of these DNA families is concentrated in certain chromosomal regions. Both DNA families exhibit biphasic TOPT curves. The presence of two thermal stability classes of hybrids suggests sequence interspersion. By co-enrichment studies in Ag+-CS2SO4 gradients, evidence suggests the origin of the three lightest density renaturated human DNA families to be satellites I, II and III.