Chromosomal distribution of rDNA in Pan paniscus, Gorilla gorilla beringei, and Symphalangus syndactylus: comparison to related primates.

Hybridization in situ was used to identify rDNA in chromosomes of the pygmy chimpanzee, mountain gorilla, and siamang gibbon. In contrast to other Pongids, and man, the gorilla has only two pairs of rDNA-containing chromosomes. The single pair in the siamang bears no resemblance to the nucleolar chromosome of the closely related lar gibbon. Pan paniscus and P. troglodytes have the same rDNA distribution, and similar karyotypes except in the structure of chromosome 23p. Grain counts over unbanded preparations show that the human, orangutan, and both chimpanzees have about the same total rDNA multiplicity.