Nucleic Acids Research, 1983, Vol. 11, No. 16 5475-5482
© 1983
MOLECULAR BIOLOGY |
Interdigitated arrangement of two oligo(A)-terminated DNA sequences in Drosophila
Laboratory of Molecular Genetics, National Institute of Child Health and Human Development, National Institutes of Health Bethesda, MD 202O5, USA
Received May 6, 1983. Accepted July 22, 1983.
A cluster of repeated sequences composed of three distinguishable units has been Isolated from Drosophila melanogaster, and characterized. The region, cloned as pDnl 158, contains a segment that 1s homologous to the type 1 Hbosomai Insertions, a member of the F family of transposable sequences, and a newly described repeated sequence that we have named 6. F elements are transposable sequences that lack terminal repeats, generate target site duplications at the point of Insertion, and contain an oligo(A) stretch at one end. 6 sequences are structurally similar though non-homologous to F 1n that they also carry an o11go(A) stretch. The structure of the 158 region of the genome 1s best explained by assuming three consecutive events. An F element did Insert Into a Hbosonal Insertion-like sequence, followed by the Introduction of a 6 sequence Into F. Subsequently, a DNA segment comprising a portion of G and F was tandemly triplicated to yield the arrangement observed. The nested Interspersion of repeated sequence elements may be a corantm feature of eukaryotic genomes.