Characterization of Gandalf, a new inverted-repeat transposable element of Drosophila koepferae.

The cloning and characterization of Gandalf, a new DNA-transposing mobile element obtained from the Drosophila koepferae (repleta group) genome is described. A fragment of Gandalf was found in a middle repetitive clone that shows variable chromosomal localization. Restriction, Southern blot, PCR and sequencing analyses have shown that most Gandalf copies are about 1 kb long, are flanked by 12 bp inverted terminal repeats and contain subterminal repetitive regions on both sides of the element. As with other elements of the DNA-transposing type (known as the 'Ac family'), the Gandalf element generates 8 bp direct duplications at the insertion point. Coding region analysis has shown that the longer open reading frame found in Gandalf copies could encode part of a protein. However, whether or not the 1 kb copies of the element are actually the active transposons remains to be elucidated. Gandalf shows a very low copy number in D. buzzatii, a sibling species of D. koepferae. An attempt to induce interspecific hybrid dysgenesis in hybrids of these two species has been unsuccessful.