Species specific variant of human centromeric DNA repeats: localization on chromosome 18 and recent amplification in human ancestral line

Plasmid library of rapidly renaturating fraction of human DNA was constructed. The library was used for isolation of primate-specific DNA repeats. A clone (1hsp-4) which was intensively hybridizable with human DNA exclusively and produced no signals when hybridized with animal DNAs including the ones from orangoutan and chimpanzee was isolated. The cloned sequences 1hsp-4 have been found to be highly specific to centromeric heterochromatin of the 18 chromosome. Primary structure of a short 1hsp-4 fragment has been determined. The obtained data suggest the emergence of a DNA family homologous to the 1hsp-4 probe to be due to the thousandfold leapwise amplification occuring less than 5-8 millions years ago.