Cloning and comparative mapping of a recently evolved human chromosome 22-specific alpha satellite DNA

We have isolated and characterized a new alphoid probe, named p190.22. Its chromosomal location was investigated using fluorescence in situ hybridization. Under high stringency conditions p190.22 recognizes specifically the centromere of chromosome 22. A chromosome 22-specific alphoid subset has been previously reported in the literature (p22/1∶2.1). The partial sequence and the genomic organization comparison strongly suggests that they recognize distinct subsets both specific for chromosome 22. The comparative mapping of probes p190.22 and p22/1∶2.1 on chimpanzee (PTR and PPA) and gorilla (GGO) chromosomes was investigated. The two probes showed different hybridization results. p190.22, in particular, did not show any hybridization signal in these three species, suggesting a recent evolution.