[Localization of E(wa) in Drosophila melanogaster using rearrangement]

The white-apricot (wa) allele differs from the wild type white gene by the presence of the retrovirus-like transposable element copia within the transcription unit. The activity of wa is reduced in trans by a semidominant mutation in the gene Enhancer-of white-apricot (E(wa)). The map position of E(wa) is refined by analyzing recombination among three genes: px, E(wa) and sp. The recombinational distance between E(wa) and sp is 0.2 cM, which places E(wa) at 2-106.8. To localize E(wa) cytologically, four Y; 2 translocations, one 1;2 translocation and three 2R deficiency stocks were crossed to the suitable E(wa) stocks and the wa sons were scored for intensity of pigment and the speck at the axis of wings. The E(wa) was placed in the distal portion of 60B. The one E(wa) mutation and two sp mutations derived from our gamma-ray mutagenesis were used for examination of polytene chromosome. The former was a revertant which has a cytologically visible insertion of material from an unknown source at 60B5-13, most likely in the 60B8-9. It is likely that this insertion is within the E(wa) gene. The latter shows breakpoint at 60C1-2, where is likely the location of the sp gene. Combining the data of both cytological localization and recombinational mapping, the E(wa) was localized at 60B5-13, most likely in the 60B8-9, the left of sp but very close to it.