Molecular structure of a somatically unstable transposable element in Drosophila.

A transposable element has been isolated from an unstable white mutation in Drosophila mauritiana, a sibling species of Drosophila melanogaster. The unstable white-peach (wpch) allele exhibits a spectrum of germ-line and somatic mutability more similar to insertion mutations in maize and in the nematode Caenorhabditis elegans than has been reported for insertion mutations in Drosophila. The inserted element mariner is 1286 nucleotides long and has terminal inverted repeats. The element contains a single open reading frame encoding 346 amino acids. A duplication of 2 base pairs of white sequence is present at the insertion site. Mariner is present in approximately 20 copies in the D. mauritiana genome, is present from 0 to 7 copies in other members of the sibling species group, and is apparently absent from the genome of D. melanogaster.