Deca-satellite: a highly polymorphic satellite that joins alpha-satellite in the African green monkey genome

Three different cloned segments of African green monkey DNA that contain alpha-satellite sequences linked to a previously undescribed, distinct monkey satellite (called deca-satellite) are described here. The cloned segments were derived from a monkey DNA library in lambda Charon 4A that was constructed to select for junctions between alpha-satellite and other DNA sequences. The structure of the deca-satellite and of a junction between deca-satellite and alpha-satellite were studied by subcloning appropriate fragments of the original cloned segments and by sequence analysis. Deca-satellite has a ten base-pair repeat unit; the consensus sequence of the repeat units is 5' A-A-A-C-C-G-G-N-T-C. Sequences homologous to the deca-satellite are in the middle repeated class of genomic DNA. Analysis of the organization of deca-satellite sequences by digestion of total DNA with various restriction endonucleases and hybridization with a cloned deca-satellite probe revealed extensive polymorphism in the genomes of different individual monkeys but not among the tissues of one organism. These observations indicate that the arrangement of deca-satellite sequences is continually changing. An unusual alpha-satellite repeat unit occurs at a junction between the alpha-satellite and deca-satellite. It resembles the major baboon alpha-satellite more closely than it does monkey alpha-satellite and thereby provides evidence in favor of the "library" hypothesis for satellite evolution.