Intermediates in synaptic vesicle recycling revealed by optical imaging of Drosophila neuromuscular junctions.
We show that uptake and release of the styryl dye FM1-43 may be used to monitor synaptic vesicle exocytosis and recycling at Drosophila larval neuromuscular junctions. At Drosophila nerve terminals, FM1-43 specifically labels subsynaptic domains enriched in synaptotagmin, in a manner that requires Ca2+, membrane depolarization, and shibire (shi) function. Endocytosis rates, very low in unstimulated synapses, are induced severalfold by the exocytosis of synaptic vesicles. Using shi(ts)1 mutant synapses to separate synaptic vesicle fusion and recycling temporally, we show that recycling events subsequent to the shi block do not require extracellular Ca2+. We suggest that two distinct intermediate stages in vesicle recycling may be trapped and analyzed at Drosophila neuromuscular junctions.
Ramaswami
M
M
Department of Biochemistry and Biophysics, University of California, San Francisco 94143-0534.
Krishnan
K S
KS
Kelly
R B
RB
D000818:Animals; D002118:Calcium / Q000502:physiology; D002135:Calcium-Binding Proteins; D029721:Drosophila Proteins; D004331:Drosophila melanogaster; D034281:Dynamins; D004705:Endocytosis; D005089:Exocytosis; D020558:GTP Phosphohydrolases / Q000502:physiology*; D008561:Membrane Fusion; D008562:Membrane Glycoproteins / Q000378:metabolism*; D008564:Membrane Potentials; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D009469:Neuromuscular Junction / Q000502:physiology* / Q000648:ultrastructure; D011188:Potassium / Q000502:physiology; D013111:Spider Venoms / Q000494:pharmacology; D009435:Synaptic Transmission; D013572:Synaptic Vesicles / Q000502:physiology*; D050857:Synaptotagmins
D002135:Calcium-Binding Proteins; D029721:Drosophila Proteins; D008562:Membrane Glycoproteins; D009419:Nerve Tissue Proteins; D013111:Spider Venoms; D050857:Synaptotagmins; D020558:GTP Phosphohydrolases; D034281:Dynamins; C439628:shi protein, Drosophila; D011188:Potassium; D002118:Calcium; C038599:black widow spider venom