Chorion cDNA clones of D. melanogaster and their use in studies of sequence homology and chromosomal location of chorion genes

Clones corresponding to two distinct A1 and A2 chorion genes have been isolated from a cDNA library in Drosophila melanogaster and characterized by hybrid-selected translation and blotting-hybridization analysis. These sequences detectably cross hybridize, thus indicating that at least some chorion genes in the fruit fly are homologous. According to in situ hybridization results, the A1 and A2 genes are not linked (mapping in regions 66D 10-12 and 54C-D of the third and second chromosomes, respectively). In conjunction with other evidence, these results suggest that in Drosophila, clustering of chorion genes may be limited to genes which are expressed in parallel during development.