CORRELATED EVOLUTION OF THE CIS-ACTING REGULATORY ELEMENTS AND DEVELOPMENTAL EXPRESSION OF THE DROSOPHILA GLD GENE IN 7 SPECIES FROM THE SUBGROUP MELANOGASTER

The tissue-specific expression patterns of glucose dehydrogenase (GLD) exhibit a high degree of interspecific variation in the adult reprodu ctive tract among the species in the genus Drosophila. We chose to foc us on the evolution of GLD expression and the evolution of the Gld pro moter in seven closely related species in the melanogaster subgroup as a means of elucidating the relationship of changes in cis-acting regu latory elements in the Gld promoter region with changes in tissue-spec ific expression. Although little variation in tissue-specific patterns of GLD was found in nonreproductive tissues during development, a sur prisingly high level of variation was observed in the expression of GL D in both developing and mature reproductive organs. In some cases thi s variation is correlated with changes in sequence elements in the Gld promoter which were previously shown to direct tissue-specific expres sion in the reproductive tract. In particular D. teissieri adult males do not express GLD in their ejaculatory ducts, atypical of the melano gaster subgroup species. The Gld promoter region of D. teissieri speci fically lacks all three of the TTAGA regulatory elements present in D. melanogaster. The TTAGA elements were previously shown to direct repo rter gene expression to the ejaculatory duct. Together these data sugg est the absence or presence of the TTAGA elements may be responsible f or variation in the absence or presence of GLD in the ejaculatory duct among species. (C) 1994 Wiley-Liss, Inc.