During the preadult development of Drosophila melanogaster, the GLD (glucose dehydrogenase) (Gld) gene is expressed in a variety of tissues, including the immature reproductive system. In adulthood, the expression of God is largely restricted to the reproductive system of men and women. We examined the expression of GLD in the adult reproductive tract of 50 species of the genus Drosophila, as well as in those of a few species representing four other closely related genera. GLD exhibits a considerable variety of specific organs in the reproductive tract of men and women.
Among these species, five male GLD phenotypes and six female GLD phenotypes were found. On the contrary, the preadult expression of GLD was determined in species representing each different type of adult pattern and was found to be highly preserved both in the immature reproductive tract and in the non-reproductive organs. In addition, the set of reproductive organs that express GLD during preadult development is equivalent to the sum of the five GLD phenotypes of men and six of adult women. To initially define the contribution of cis action factors to the transacting factors responsible for the differences in the expression of GLD in adults between two of these species, D.
Pseudoobscura Gld, to the D. GLD genome, the expression patterns of these transformants showed characteristics that are unique to both species, suggesting the presence of both cis and transactional differences between these two species.