THE AUTOSOMAL CHORION LOCUS OF THE MEDFLY CERATITIS-CAPITATA .1. CONSERVED SYNTENY, AMPLIFICATION AND TISSUE-SPECIFICITY BUT SEQUENCE DIVERGENCE AND ALTERED TEMPORAL REGULATION

We report the isolation, full sequence characterization, amplification and expression properties of medfly chorion genes corresponding to th e autosomal chorion locus of Drosophila. These genes are found adjacen t to the paramyosin gene and are organized in the same order and tande m orientation as their Drosophila homologues, although they are spaced further apart. They show substantial sequence divergence from their D rosophila homologues, including novel peptide repeats and a new spacin g of the tyrosines, which are known to be cross-linked in Dipteran cho rion. The genes are amplified and expressed during oogenesis, as in Dr osophila. Three of them are expressed in the same relative temporal or der as in Drosophila but the fourth gene, the homologue of s15, shows a clear shift to an earlier expression period. This is the first known instance of changed temporal regulation in dipteran chorion genes.