FIGURE 2.

(A) Tissue-specific expression of the Gal4 transcription factor was used to drive miRNA sponge expression under the control of upstream activating sequences (UAS) in transgenic fruit flies. (B) Dissection of a complex phenotype using tissue-specific sponges. A developmental defect in the axonal branching and synaptic boutons of neuromuscular junctions (NMJ) was observed in the miR-8 knockout (second panel) and in miR-8 heterozygous flies expressing a miR-8 sponge inhibitor specifically in muscle (fourth panel). Wild-type appearance of the NMJ is seen in the miR-8 heterozygote (first panel) and in miR-8 heterozygous flies expressing a miR-8 sponge specifically in neurons (third panel). Sponge expression is indicated by GFP fluorescence (shown in green).