MUTATIONS AT THE DARKENER OF APRICOT LOCUS MODULATE TRANSCRIPT LEVELSOF COPIA AND COPIA-INDUCED MUTATIONS IN DROSOPHILA-MELANOGASTER

Mutations of the Doa locus of Drosophila melanogaster darken the eye c olor of the copia-induced white(apricot) (w(a)) allele and increase th e accumulation of white promoter-initiated transcripts encoding functi onal mRNA. We show here that quantities of transcripts initiated in bo th long terminal repeats (LTRs) of the specific w(a)-copia element are increased, and those initiating in the 5' LTR of the element are stru cturally altered, yielding a slightly shortened transcript. Accumulati on of host-initiated transcripts of a copia-induced mutation within th e achaete-scute complex, Hairy-wing(Ua) (Hw(Ua)), are reduced by Doa m utations. Finally, we show that homozygosity for Doa mutations increas es the accumulation of copia transcripts from the population of elemen ts in the genome. These results suggest that Doa modulates the severit y of copia-induced mutations while functioning as a dosage-sensitive m odulator of copia transcription.