New orientations of ancestral, "long interspersed repeated sequences" (LINES) in human DNA.

Three sets of long, interspersed repeated sequences (LINES) are described in human DNA. Each set contains two cleavage sites for the restriction endonuclease, XbaI. One set, called the Xba 850 LINES was detected only in gibbons, apes and man but is related in sequence to a more ancestral LINES family, the Kpn 1200 LINES, and in fact some Xba 850 LINES members retained the ancestral spacing of KpnI cleavage sites. The facts that the Xba 850 LINES appear as a subset of the Kpn 1200 LINES and vice versa and that the Xba 850 LINES are restricted to a smaller phylogenetic group than the Kpn 1200 LINES prompted the speculation that the Xba 850 LINES originated by a relatively recent amplification of one or a few Kpn 1200 LINES sequences.