Isolation of low-copy-number sequences that neighbor satellite DNA in mammals

To investigate the role of satellite DNA in eukaryotic genomes, we isolated from an African green monkey (Cercopithecus aethiops) genomic library cloned segments containing the previously described deca-satellite linked to low-copy-number genomic sequences. Three such clones were obtained. The low-copy-number sequences in the three clones do not cross-hybridize suggesting that they derive from different genomic loci. The structure of one of the clones, lambda MkA, is described in detail. Subcloned segments containing the low-copy-number sequences from lambda MkA anneal to monkey, human and mouse genomic DNA. The subcloned probes were used to select clones containing homologous sequences from a second, independent monkey library as well as from human and mouse genomic libraries. Several of the newly isolated monkey clones hybridized to probes containing the species-specific deca- and alpha-satellites, confirming the genomic association of the low-copy-number sequence in lambda MkA with satellite DNA. Moreover, several of the human and mouse clones hybridized to species-specific human and mouse satellite DNAs, respectively. These experiments indicate that the low-copy-number sequence in lambda MkA and its association with satellite DNA is conserved in primates and rodents.