An alphoid DNA sequence conserved in all human and great ape chromosomes: evidence for ancient centromeric sequences at human chromosomal regions 2q21 and 9q13.

Using vector-CENP-B box polymerase chain reaction (PCR) we isolated and cloned from a human chromosome 21-specific plasmid library, a 1 kb DNA sequence, named p alpha H21. In in situ hybridization experiments, p alpha H21 hybridized, under high stringency conditions, to the centromeric region of all the human, chimpanzee, gorilla and orangutan chromosomes. On human chromosomes p alpha H21 also identified non-centromeric sequences at 2q21 (locus D2F33S1) and 9q13 (locus D9F33S2). The possible derivation of these sequences from ancestral centromeres is discussed. Sequence analysis confirmed the alphoid nature of the whole p alpha H21 insert.