Fig. 1. Molecular characterization of sec6 excisions. The genomic region 55E1-3 is shown, with an enlargement of the immediate vicinity of sec6. Df(2R)PC4 was found to remove the sec6 locus by in situ hybridization to polytene chromosomes (data not shown). The P-element EP2021 (small triangle), located just 3' to sec6 and within the 5' untranslated region of the adjacent gene Eip55E was excised to give rise to three deletions, Ex15, Ex228 and Ex212 (heavy bars). Primers 1-6 were used to amplify DNA from these lines and the extent of the deleted regions was determined by DNA sequencing. Two of the three excisions, Ex15 and Ex228, remove coding sequence from sec6 and 21 base pairs of non-coding sequence from Eip55E. Ex212 removes a 34 kb genomic fragment extending from predicted gene CG30332 to CG30122, as shown.