DIVERGENT AND CONSERVED FEATURES IN THE SPATIAL EXPRESSION OF THE DROSOPHILA-PSEUDOOBSCURA ESTERASE-5B GENE AND THE ESTERASE-6 GENE OF DROSOPHILA-MELANOGASTER

The regulatory regions of homologous genes encoding esterase 6 (Est-6) of Drosophila melanogaster and esterase 5B (Est-5B) of Drosophila pse udoobscura show very little similarity, We have undertaken a comparati ve study of the pattern of expression directed by the Est-5B and Est-6 5'-flanking DNA to attempt to reveal conserved elements regulating ti ssue-specific expression in adults, Esterase regulatory sequences were linked to a lacZ reporter gene and transformed into D. melanogaster e mbryos, Est-5B, 5' upstream elements, give rise to a beta-galactosidas e expression pattern that coincides with the wild-type expression of E st-5B in D. pseudoobscura. The expression patterns of the Est-5B/ lacZ construct are different from those of a fusion gene containing the up stream region of Est-6, Common sites of expression for both kinds of c onstructs are the third segment of antenna, the maxillary palps, and s alivary glands, In vitro deletion mutagenesis has shown that the two g enes have a different organization of regulatory elements controlling expression in both the third segment of antenna and maxillary palps, T he results suggest that the conservation of the expression pattern in genes that evolved from a common ancestor may not be accompanied by pr eservation of the corresponding cis-regulatory elements.