Vha100-14 mutant photoreceptor clones display defects in neurotransmission, as shown by loss of "on" transients in electroretinogram (ERG) recordings.
The electroretinogram of mutant photoreceptors lacks the on transient.
Mutant photoreceptor neurons show a reduction in acidification (measured using Lysotracker fluorescence) at 40% of pupal development compared to wild-type cells. Acidification before neuronal differentiation is normal in the mutants.
Mutant photoreceptor terminals contain aberrant multivesicular structures and double-membrane autophagosomal vacuoles.
Animals expressing Vha100-1R755A.Scer\UAS under the control of Scer\GAL4unspecified in a Vha100-14 background show loss of photoreceptors and have a reduced eye phenotype.
The electroretinogram depolarisation is indistinguishable from wild type in 1 week old mutant photoreceptors. However, a weak reduction in depolarisation becomes apparent after 3 weeks and progressively worsens by 5 weeks. This progressive reduction in depolarisation is seen under both 12 hour light: 12 hour dark and constant darkness conditions. The 5 week old mutant photoreceptors show a loss of most discernible rhabdomere structure.
Flies in which the retina is homozygous for Vha100-14 (made using the 'ey-flp' system described in FBrf0125463) consistently fail to walk toward light in a phototaxis assay. Electro-retinograms from these animals display normal depolarization in response to light stimuli, but exhibit a complete loss of 'on' and 'off' transients, indicative of a failure to evoke a postsynaptic response.