Mutants die at pupal stage P3. Third instar larvae lack imaginal discs and show an undersized CNS. The gross morphology of imaginal discs and CNS in second instar larvae appears normal. No BrdU incorporation is seen in third instar brains, reflecting lack of cell proliferation, whereas 2nd instar brains appear normal.

Homozygous first and second instar larvae show normal morphology and locomotor/feeding behaviour. Third instar larvae show progressively less vigorous locomotion and feeding. Many mutants grow to normal size but remain in the food past the normal wandering stage and delay pupation for several days beyond the normal period. Neuromuscular morphology of mutants shows only minor alterations. Terminal branching pattern is similar to wild type, however mutants have 20% fewer terminal branches, due to fewer higher order branch segments at mutant terminals (assayed at muscle 12). This results in similarly reduced numbers of boutons on muscle 12 and 6/7, but not muscle 4. Mutant EJC amplitudes (muscle 12 and muscle 6) are significantly larger than wild type at all Ca²⁺ concentrations. mEJCs display no significant differences in mean amplitude, variability, spontaneous frequency or current decay kinetics compared to wild type. Short term synaptic facilitation, synaptic augmentation and posttetanic potentiation are strongly impaired in mutants. Synaptic plasticity defects are incompletely restored by reducing basal transmitter release.

Decrement in 15-minute memory retention.