Cloning and analysis of the dec-1 female-sterile locus, a gene required for proper assembly of the Drosophila eggshell.

Female-sterile mutations at the dec-1 (defective chorion-1) locus of Drosophila severely disrupt the organization of the eggshell late in oogenesis. Previous characterization of dec-1 mutations has correlated the defects with failure to accumulate an early eggshell protein that undergoes proteolytic cleavage during choriogenesis. To enable further study of the regulation and processing of dec-1 products, we have molecularly cloned the locus and characterized its transcripts. Chromosome jumping was used to isolate a deficiency breakpoint within the locus. Overlapping genomic clones from a wild-type library were then obtained, and a region including the dec-1 locus was identified by hybridization to cDNA probes complementary to RNA from stage 9-10 egg chambers. Analysis of genomic rearrangements associated with the locus verified its identity. Two transcripts from the locus have been identified and characterized using cDNA clones, RNase protection, and primer extension analyses. A 4.0-kb transcript accumulates maximally in stages 9-10, when the primary follicle cell protein associated with dec-1 mutations is synthesized. A second transcript of 5.8 kb, generated by alternative splicing, accumulates during stages 11-12. These results are discussed in light of previous analysis of dec-1 mutations.