Fig. 1.

Enhancer-detector insertion sites upstream of Drosophila mef2. Insertion sites of the P element (P[lArB]) are shown for the nine enhancer-detector lines. A single arrow represents independent insertions that are within 200 base pairs of each other. The direction of the arrows indicates the direction of lacZ transcription, which encodes β–galactosidase. The locations of fragment MB247, which drives expression in MB and antennal lobe, and a fragment that drives expression in muscle, were derived from Schulz et al. (1996). The putative location of a second MB enhancer, and an enhancer for the developing wing, are defined by the expression and phenotypes we found in the enhancer-detector lines. The mef2, FMRFamide and eve gene structures and the breakpoints of the deletions are based on previous studies (Bour et al., 1995; Lilly et al., 1995; O'Brien et al., 1994; Schulz et al., 1996). Open boxes of the mef2 transcription unit represent untranslated exons and filled boxes represent exons in the open reading frame.