Figure 8

K222 integrated into the primate germline after the divergence of New and Old World monkeys and expanded in copy number during the evolution of humans. (A) Genomic organization of centromeric K111 and K222 proviruses. The positions of the primers used to amplify K222 insertions by PCR and qPCR are indicated by arrows. (B) Detection of K222 from DNA of New and Old-World primates. K222 was detected by PCR with the primers K222F and K222bR in the baboon, orangutan, gorilla, chimpanzee, and human, but not in macaques, African green monkeys, and New World monkeys. Other bands (for example, the PCR products detected in mouse, hamster, and rhesus macaque) were shown by sequencing to be the result of non-specific PCR amplification. A phylogeny of New World monkeys, Old World monkeys, and hominoids (humans and apes) is shown. Estimated times of divergence are shown. MYA: million years ago. (C) Quantitation of K222 copies by qPCR in the genomes of Old World monkeys, humans, and a number of other primates. K222 is likely present as a single copy in the genomes of baboon, orangutan, gorilla and chimpanzee, while present in multiple copies in the human genome. The label of each species in (B) matches to the bars.