Visualization of synaptic specializations in live C-elegans with synaptic vesicle protein-GFP fusions

Synaptic specializations are difficult to visualize at the light microscope level in living preparations. To circumvent this problem, synaptic vesicle proteins were fused to green fluorescent protein (GFP) and expressed in C. elegans neurons. C. elegans synaptobrevin-GFP and synaptogyrin-GFP fusion proteins were observed to target to synaptic sites. This localization allow ed the visualization of synaptic specializations in living animals with lig ht microscopy. Restricted expression of synaptobrevin-GFP fusions in subset s of neurons enables the visualization of individual presynaptic varicositi es. The cell biology underlying the sorting of synaptic vesicle proteins, t rafficking of vesicles to terminals, and the development of presynaptic spe cializations is now more amenable to forward genetic analysis using these s ynaptic markers. (C) 1999 Elsevier Science B.V. All rights reserved.