Interaction of the mottler of white with transposable element alleles at the white locus in Drosophila melanogaster.

The mottler of white (mw) locus has been determined to interact with alleles of the white (w) eye color locus which are a subset of the transposable element insertion mutants. The transposable elements belong to six different types, including copia, and are located at several sites within the w gene. Three X-ray-induced revertants of white-apricot (wa) no longer respond to mw, indicating that the transposable element must be present for mw to act. The mottling property of the original allele was analyzed by combining the mw mutant with extra copies of wa, either in a tandem duplication or in a transposable segment on chromosome two. Because neither duplication alters the mottling pattern, the event that results in the mottled pattern must occur at mw and not at w. The pattern of a deficiency for the locus heterozygous with the original allele differs from that of mw/mw females, confirming that this unique mottling property occurs at mw. A new allele of mw was induced in hybrid dysgenic crosses. It is not mottled, slightly enhances wa as a heterozygote, and further enhances as a homozygote or hemizygote. An analysis of RNA from wa with mw shows a reduction of the full-length normal RNA and a concomitant increase in certain RNAs that terminate within the copia element. These results suggest that several retrotransposon-induced alleles share an RNA processing function encoded by mw.