Abstract
The unstable white-S2 (wS2) allele of the white gene occurred spontaneously in the S2 strain of Drosophila simulans. This mutation was caused by insertion of the submariner element, a mariner-like element with an abnormal tandem duplication of the 5' inverted terminal repeat (ITR). Although it has an incomplete ITR, submariner excises efficiently. The rate of somatic reversion, estimated by the number of eye-color mosaic flies, was 79.9%, and the reversion frequency in the germline was 0.6%. The change to the 5' ITR contributes to make this transposon precise excision.
