Scer\FRT-mediated recombination between the two progenitor insertions has deleted the sequence between them.
The third instar larval neuromuscular junction of Df(3R)RhoGAP100Fex1.2/Df(3R)RhoGAP100Fex3.4 transheterozygotes does not show any active zone (identified by Bruchpilot puncta) density defects, as compared to controls.
T-bars at active zones of the neuromuscular junction in Df(3R)RhoGAP100Fex1.2/Df(3R)RhoGAP100Fex3.4 third instar larvae often show an aberrant, star-shaped morphology.
Df(3R)RhoGAP100Fex1.2/Df(3R)RhoGAP100Fex3.4 adults appear morphologically normal and under optimal culturing conditions, eclose at close to the Mendelian ratio. However, more than 80% of the adults die within one week. The adult flies show severely impaired locomotion (assayed both by walking ability on a flat surface and in a negative geotaxis assay).
Evoked excitatory junctional currents (EJCs) are significantly reduced in amplitude in Df(3R)RhoGAP100Fex1.2/Df(3R)RhoGAP100Fex3.4 third instar larvae compared to controls, while the amplitude of spontaneous miniature EJCs is normal.
The overall size of the neuromuscular junction (NMJ) is reduced in Df(3R)RhoGAP100Fex1.2/Df(3R)RhoGAP100Fex3.4 third instar larvae compared to controls. Ultrastructurally, T bars at the NMJ often appear irregular in shape, with pedestals of very high diameter and multiple, atypically prominent filamentous projections in their distal parts. In addition, atypically small T bar-like assemblies are seen. Ectopic electron-dense material is seen at the mutant NMJ, frequently being seen at the edge of active zones and only loosely, if at all, being associated with the presynaptic plasma membrane. Floating electron-dense material, highly decorated with synaptic vesicles, is seen in the bouton interior.
Df(3R)RhoGAP100Fex1.2 mutant larvae exhibit a vesicle localization phenotype, with ectopic aggregates of VGlut1 present at distal axon regions just proximal to the synaptic nerve terminal. This ectopic accumulation near synaptic termini occurs early in synaptic development and is not attributable to a gradual accumulation of synaptic vesicles during synaptic terminal growth.
