A section of DNA important for expression in all cell types was subdivided and reintroduced into the mutated control region, a piece at a time, to identify which portion was required for promoter activity. We identified a 55, a 214 and a 20 nucleotide sequence that control promoter activity. Different combinations of these elements activate the promoter in adult muscle, larval muscle and in tracheal cells. Behavioral and Electrophysiological Analysis of Ca-activated K channel transgenes in Drosophila. Here we describe and contrast the regulation of neuronal and muscle expression during embryogenesis with its regulation during larval and adult stages.
Embryonic regulation is fundamentally different.
The embryo uses Promoter C1 and a previously undescribed promoter, called Promoter Ce, to drive neuronal expression. The expression patterns of these promoters are distinct. Muscle expression arises from Promoter C2 as in other developmental stages. A downstream intronic region has been shown to contain control elements that modulate promoter activity differently in embryos, larvae and adults. In embryonic muscle, removal of the intron eliminates muscle expression even though this deletion does not reduce larval muscle expression.