Individual and evolutionary variation of primate ribosomal DNA transcription initiation regions

A 16-kilobase region surrounding the transcription initiation site for ribosomal DNA and including the entire ribosomal DNA transcription unit has been characterized in man and compared in higher primates. Restriction analysis of ribosomal DNA from the pygmy chimpanzee (Pan paniscus), the common chimpanzee (Pan troglodytes), the gorilla (Gorilla gorilla), the orangutan (Pongo pygmaeus), the gibbon (Hylobates lar), and the rhesus monkey (Macaca mulatta) allows a primate phylogeny to be constructed based on ribosomal DNA structure. Individual variation and methylation are demonstrated in the ribosomal DNA repeats of all primates examined. Restriction analysis with HincII endonuclease suggests cleavage at sites containing methylated CpG and adds the SalI/HincII pair to those enzymes useful for studying DNA modification.