Similar tissue-specific expression of the Adh genes from different Drosophila species is mediated by distinct arrangements of cis-acting sequences

In Drosophila melanogaster transformants, the alcohol dehydrogenase (Adh) genes from D. affinidisjuncta and D. grimshawi show similar levels of expression except in the adult midgut where the D. affinidisjuncta gene is expressed about 10- to 20-fold more strongly. To study the arrangement of cis-acting sequences responsible for this regulatory difference, homologous restriction sites were used to create a series of chimeric genes that switched fragments from the 5 and 3 flanking regions of these two genes. Chimeric genes were introduced into the germ-line of D. melanogaster, and Adh gene expression was analyzed by measuring RNA levels. Various gene fragments in the promoter region and elsewhere influence expression in the adult midgut and in whole larvae and adults. Comparison of these results with earlier studies involving chimeras between the D. affinidisjuncta and D. hawaiiensis genes indicates that expression in the adult midgut is influenced by multiple regulatory sequences and that distinct arrangements of regulatory sequences can result in similar levels of expression both in the adult midgut and in the whole organism.