Over-expression of SypScer\UAS.T:Avic\GFP driven in muscle by Scer\GAL4Mhc.PW results in underdeveloped synapses at the neuromuscular junction (NMJ) of third instar larvae, with significant decreases in branch number and type Ib bouton numbers, and significant decreases in total bouton number (no change in the ratio of 1b bouton to total bouton numbers), compared to wild type; type Ib boutons also appear abnormally large and fused. Pan-neuronal over-expression of SypScer\UAS.T:Avic\GFP driven by Scer\GAL4elav-C155 results in synapse overgrowth at the neuromuscular junction (NMJ) of third instar larvae, with significant increases in branch number and type Ib bouton numbers, and significant increases in total bouton number (no change in the ratio of 1b bouton to total bouton numbers), compared to wild type.