Long interspersed sequences in mammalian DNA. Properties of newly identified specimens.

The genomes of primates and of rodents contain numerous long interspersed sequences or LINEs, which are mutually homologous and show characteristics of inserted reverse transcripts or retroposons. Here I report the identification of five new specimens in published DNA sequences, including the first two examples from the rat. These specimens demonstrate the generality of certain sequence arrangements seen in LINEs, viz.: 5' truncation; internal inversion with deletion; clustering with other retroposons; and evolutionary divergence at the 3' end. The 3' segments show a patchwork pattern of homology suggestive of frequent sequence exchanges between multiple subfamilies.