title: Interdigitated arrangement of two oligo(A)-terminated DNA sequences in Drosophila.
abstract: A cluster of repeated sequences composed of three distinguishable units has been isolated from Drosophila melanogaster, and characterized. The region, cloned as pDmI 158, contains a segment that is homologous to the type 1 ribosomal insertions, a member of the F family of transposable sequences, and a newly described repeated sequence that we have named G. 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. G sequences are structurally similar though non-homologous to F in that they also carry an oligo(A) stretch. The structure of the 158 region of the genome is best explained by assuming three consecutive events. An F element did insert into a ribosomal insertion-like sequence, followed by the introduction of a G 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 common feature of eukaryotic genomes.
mesh_terms: D000227:Adenine Nucleotides / Q000032:analysis*; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics*; D004262:DNA Restriction Enzymes; D004331:Drosophila melanogaster / Q000235:genetics*; D009693:Nucleic Acid Hybridization; D009841:Oligonucleotides / Q000032:analysis*; D009843:Oligoribonucleotides / Q000032:analysis*
chemical_list: D000227:Adenine Nucleotides; D009841:Oligonucleotides; D009843:Oligoribonucleotides; C023505:2',5'-oligoadenylate; D004247:DNA; D004262:DNA Restriction Enzymes