abnormal neuroanatomy | conditional (with lap1), with lapC.4C.Tag:FLAG,Tag:CALI(TC)
lethal (with lapKG06751)
The amplitude of excitatory junctional potentials (EJPs) in lap1/lapsd-3 mutants is drastically reduced relative to controls.
When larvae expressing lapN.4C.T:Zzzz\FLAG,T:Zzzz\TC in a lap1/lapsd-3 mutant background are pretreated with FlAsH-FALI and photoinactivated to inactive lap, they show synaptic vesicle endocytosis defects (reduced dye internalisation) in the NMJ when stimulated with potassium. Unlike in wild type and unactivated controls, only small punctae of dye are detected within the synaptic boutons. Inactivation of lap has no effect on synaptic vesicle exocytosis or transmitter release. When lap is inactivated just prior to potassium stimulation boutons are seen that display acute synaptic membrane protrusions ("pseudopodia"), and these are not observed in controls. Normal sized synaptic vesicles are rarely observed and two categories of phenotype are seen 1) boutons packed with multiple intermediate-sized cisternae or 2) boutons exhibiting massive synaptic vesicle depletion, but containing very large cisternae and membrane infoldings. Large balloon-like membrane infoldings that remain contiguous with the plasma membrane and may also contain smaller vesicle-like structures, are also seen.
Mosaic animals in which the retina is homozygous for lapsd-3 (generated using the "EGUF/hid" system) have normal external eye morphology but show defects in a phototaxis assay. The electroretinogram of mosaic animals in which the retina is homozygous for lapsd-3 has defective on/off transients. Photoreceptor axon projection patterns in these animals are essentially indistinguishable from controls. Hemizygotes die as first instar larvae and homozygotes die as pupae with rare adult escapers.
lapsd-3/lap1 is rescued by lapN.4C.Tag:FLAG,Tag:CALI(TC)
lapsd-3/lap1 is partially rescued by lapC.4C.Tag:FLAG,Tag:CALI(TC)
Expression of lapC.4C.T:Zzzz\FLAG,T:Zzzz\TC partially rescues the reduction in excitatory junctional potential (EJP) amplitude seen in lap1/lapsd-3 mutants. The larval lethality is also rescued.
Expression of lapN.4C.T:Zzzz\FLAG,T:Zzzz\TC almost completely rescues the reduction in excitatory junctional potentials (EJPs) amplitude seen in lap1/lapsd-3 mutants. The larval lethality is also rescued.