Organization of the variant domains of alpha satellite DNA on human chromosome 21.

The de novo creation of long, homogeneous, satellite DNA domains was postulated previously to occur by saltatory amplification. In this paper, pulsed field gel electrophoresis analysis of the alpha satellite DNA block organization of the human chromosome 21 supports this hypothesis. Double-dimension electrophoresis indicated that the variant copies of the basic alpha satellite repeat of chromosome 21 are organized in a single 3,150 Kb-long domain. It was also established that the other satellite DNAs found in man (beta, II, and III) are organized independently of the alpha satellite DNA block of the same chromosome.