Expressing Rab5S43N.UAS under the control of Scer\GAL4ppk.PU induces enlarged endosomes but does not affect mitochondria localization in white prepupal ddaC neurons' cell bodies, as compared to controls.
The third instar larval neuromuscular junction of individuals expressing Rab5S43N.Scer\UAS under the control of Scer\GAL4da.G32 exhibits the accumulation of large presynaptic endocytic vesicles, as compared to controls.
Animals expressing Rab5S43N.Scer\UAS under the control of Scer\GAL4grh.D4 are lethal, show defects in larval dorsal trunk elongation (resulting in internalization of posterior spiracles into the body cavity) and the larvae are smaller than age-matched controls.
The class IV dendritic arborization neurons in flies expressing Rab5S43N.Scer\UAS under the control of Scer\GAL4ppk.PG show a significant decrease in the complexity of dendritic arbors.
Third instar larvae expressing Rab5S43N.Scer\UAS under the control of Scer\GAL4VGlut-OK371 show a significant increase in the number of boutons per muscle area at the neuromuscular junction (NMJ) compared to controls and the boutons are smaller than normal. Class IV da neurons show mild defects in dendrite morphogenesis: total dendritic length is decreased by 11% and the number of branch endings per cell is decreased by 19%, while the coverage index is not altered.
Adults expressing Rab5S43N.Scer\UAS under the control of Scer\GAL4VGlut-OK371 show a significant increase in the number of boutons per muscle area at the neuromuscular junction (NMJ) compared to controls.
Expression of Rab5S43N.Scer\UAS under the control of Scer\GAL4da.G32 affects dorsal closure. The amnioserosa cells are irregular in shape with big lamellipodia during the early stages of dorsal closure. Later on, epidermal elongation is impaired and puckering is seen. Dorsal closure fails, with the embryos having a conspicuous dorsal hole in the cuticle.
Expression of Rab5S43N.Scer\UAS under the control of Scer\GAL4c381 results in changes in amnioserosa cell morphology during early and late stages of dorsal closure, but epidermal cell elongation is not compromised and the embryos complete dorsal closure.
Expression of Rab5S43N.Scer\UAS under the control of Scer\GAL4en-e16E has no visible effect on dorsal closure.
Third-instar larval eye discs expressing dominant negative Rab5S43N.Scer\UAS in the posterior region of the under control of Scer\GAL4GMR.PF display normal morphology, with differentiating R-cells in the eye disc expressing normal R-cell developmental markers. However, many R-cell nuclei fail to maintain their apical localization and instead mis-localize basally.
Mutant neurons in the third instar larva expressing Rab5S43N.Scer\UAS show reduced branch numbers and sprout much less in the proximal area than wild-type neurons. Neurons expressing Rab5S43N.Scer\UAS extend axons and major dendritic branches, however, they display greatly simplified dendritic arbors and decreased number of terminal branches compared with that found for wild-type neurons.
Expression of Rab5S43N.Scer\UAS in border cells, driven by Scer\GAL4slbo.2.6, results in the absence of the apical cap in stage 8 egg chambers, as compared with wild type. Among clusters still showing a cap, 47% show a micro cap. The migration of border cell clusters to the oocyte is defective.
The average number of crystal cells per embryo is reduced compared to wild type in stage 13-14 embryos expressing Rab5S43N.Scer\UAS under the control of Scer\GAL4srp.
Expression of dominant-negative Rab5S43N.Scer\UAS under the regulation of Scer\GAL4elav-C155 at low levels during embryonic and early larval stages at 16oC and at higher levels at 25oC during the last two days of larval development does not cause a developmental phenotype of the neuromuscular junctions. The synaptic surface area is normal in Rab5S43N.Scer\UAS-expressing synapses. In addition, Rab5S43N.Scer\UAS-expressing motoneurons display a normal number and morphology of endocytosis centers and active zones of exocytosis. In Rab5S43N.Scer\UAS synapses (under the regulation of Scer\GAL4elav-C155) small, 70nm vesicles are more frequently observed than in wild-type, indicating that these endocytic vesicles are unable to fuse efficiently with early endosomes. In wild-type and Rab5S43N.Scer\UAS (Scer\GAL4elav-C155) synapses, FM1-43 styryl dye recycling experiments reveal that the rate of FM1-43 internalisation is 2.5-fold slower in Rab5S43N.Scer\UAS synapses compared to wild-type. Synapse release is also affected in Rab5S43N.Scer\UAS mutants. FM1-43-release experiments reveal that release occurs 2.5 times slower during the first 5min in Rab5S43N.Scer\UAS synapses compared to wild-type, indicating that impaired Rab5 function reduces small vesicle release. Miniature excitatory junction potential (mEJP) recordings from Rab5S43N.Scer\UAS mutant neuromuscular junctions display no significant differences in mean frequency, amplitude, variability, or voltage decay kinetics compared to wild-type mEJPs. This indicates that presynaptic expression of Rab5S43N.Scer\UAS does not affect the vesicular neurotransmitter content, the number of fusion competent vesicles, or the postsynaptic glutamate receptor function or density. Consistently, a normal number of docked vesicles is observed at the ultra-structural level, and no difference in the overall morphology, synaptic surface area, or active zones is detected. Mean quantal content decreases by around 50% in Rab5S43N.Scer\UAS; Scer\GAL4elav-C155 neuromuscular junctions. Rab5S43N.Scer\UAS, under the regulation of Scer\GAL4elav-C155 does not significantly alter the synaptic area, nor the active zone density of presynaptic terminals, implying that the total number of active zones is normal.