Localization of human midisatellite and macrosatellite DNA sequences on chromosomes 1 and X in the great apes

The mechanism of speciation has remained largely unresolved, and hominoid e volutionary history based on chromosome rearrangements has been continuousl y challenged. The recent availability of the human-derived chromosome 1-spe cific midisatellite (D1Z2) and chromosome X-specific macrosatellite (DXZ4) DNA sequence probes has prompted us to hybridize the aforementioned to the members of the hominoid clade (chimpanzee, gorilla, and orangutan), using t he fluorescence in-situ hybridization technique. Inconsistencies in the hyb ridization pattern for the D1Z2. DNA probe in the great ape species suggest s that changes in this sequence have apparently taken place during the evol utionary process. No hybridization signal was observed in the orangutan chr omosome 1, suggesting that a homologous D1Z2 DNA sequence may not be presen t in its genome, or that the sequence may be altered, rendering itself unde tectable by human-derived DNA probes. Homology in the hybridization pattern s for the DXZ4 probe in all three ape species illustrates that the sequence is apparently conserved. Such hybridization data provide some level of phy logenetic information on the recent ancestry of higher primates.