Pan-neural expression of Vap-33AV260I.Scer\UAS under the control of Scer\GAL4elav-C155 results in changes in the neuromuscular junction, with an increase in the total number of synaptic boutons, compared to controls. Bouton size, however, is dramatically reduced. Many small boutons appear to bud off from a central bouton or from neuronal processes connecting two boutons. Indeed, presynaptic expression of Vap-33AV260I.Scer\UAS induces a 2.6-fold increase in the percentage of 'satellite' boutons compared to controls.
Neuronal expression of Vap-33AV260I.Scer\UAS under the control of Scer\GAL4elav-C155 affects the organization of microtubule architecture, with consequences on synaptic bouton formation and division.
Post-synaptic expression of Vap-33AV260I.Scer\UAS under the control of Scer\GAL4C57 induces aggregate formation and changes in nuclear shape, size and positioning. Muscle fiber nuclei are more closely associated in these mutants and exhibit a tendency to cluster. The nuclei are also deformed into an elongated structure and display a marked enlarged nuclear volume compared to controls. In addition, an increased number of small and condensed pyknotic nuclei are observed in these muscles.
Large, malformed nuclei are observed in larval brains expressing Vap-33AV260I.Scer\UAS under the control of Scer\GAL4elav-C155. These neurons exhibit prominent inclusions that appear to be very large and intensely immunoreactive to Vap-33A.
Flies expressing Vap-33AV260I.Scer\UAS under the control of Scer\GAL4elav-C155 are able to pupate. However, there is a strong reduction in the number of flies eclosed as viable adults in these mutants, with only 35% of pupae eclosing to viable adults. These flies display distinctive postural and locomotion defects as viable adults, such as droopy and held-up wings. These flies are severely uncoordinated and within a few days of eclosion find themselves stuck to their food and die.
Targeted expression of Vap-33AV260I.Scer\UAS in the adult eye, under the control of Scer\GAL4ey.PU, results in a range of structural abnormalities. Compared to controls, these eyes are reduced in size and show a marked roughness over the entire surface. There is a high degree of heterogeneity in the severity of the phenotype within the same line and indeed in the same fly. Overall, the eye size of Vap-33AV260I.Scer\UAS-expressing mutants is less than 50% of the control size. Photoreceptor morphology is disrupted in these flies, with several vacuoles found.