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 (A dh) 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 ar rangement of cis-acting sequences responsible for this regulatory diff erence, homologous restriction sites were used to create a series of c himeric genes that switched fragments from the 5' and 3' flanking regi ons of these two genes. Chimeric genes were introduced into the germ-l ine of D. melanogaster, and Adh gene expression was analyzed by measur ing RNA levels. Various gene fragments in the promoter region and else where influence expression in the adult midgut and in whole larvae and adults. Comparison of these results with earlier studies involving ch imeras between the D. affinidisjuncta and D. hawaiiensis genes indicat es that expression in the adult midgut is influenced by multiple regul atory sequences and that distinct arrangements of regulatory sequences can result in similar levels of expression both in the adult midgut a nd in the whole organism.