hiwND9 third instar larvae exhibit dramatic overgrowth of the neuromuscular junction, namely increased branching and increased number of presynaptic boutons, as compared to controls.
hiwND9 mutants display significantly enhanced aversive long term memory after one-session or two-session spaced training, but show normal long term memory after ten-session spaced training. Sensorimotor abilities are unchanged compared with controls. hiwND9 mutants show a normal memory three hours after training and a slightly but not significantly elevated memory at 8 hours, whereas they exhibit significantly enhanced memory at the 12 hours and 24 hour time points compared with controls. Short term and intermediate term memory are similar to controls.
The enhancement of aversive long-term memory seen in hiwND9 mutant flies is eliminated when the flies are fed the protein synthesis inhibitor cycloheximide.
Mutant larvae show synaptic terminal overgrowth at the neuromuscular junction, with an increase in bouton number compared to wild type.
Homozygotes or hemizygotes over Df(1)RK2 or Df(1)RK4 all have synapses that are longer and more branched with more numerous but smaller boutons.