alpha DNA in African green monkey cells is organized into extremely long tandem arrays

We have determined the size of arrays formed by tandemly repeated monomers of alpha DNA in African green monkey cells. DNA fragments containing intact alpha DNA arrays were generated by digestion of genomic DNA with restriction endonuclease that do not have sites in the alpha DNA consensus sequence. Their size was determined by Southern analysis and by sedimentation through neutral sucrose gradients followed by probing of each fraction for alpha sequences. The restriction fragments varied in size with the most frequent being 78 kilobase pairs long. We have also shown that they contain very little non-alpha DNA sequences. This suggests a minimum array of 450 tandemly repeated alpha DNA monomers, which is more than an order of magnitude larger than previously supposed.