( When nerve cells excite muscle fibers t...)Fast-freeze snapshot yields new picture of nerve-muscle junction

Several proteins that have been shown to be major players in synaptic transmission have now been studied using a flash-freeze physical-fixation technique that reveals new details of their location and function in neuromuscular synapses. The technique was used with tiny, one-millimeter-long nematode worms, a lab animal widely studied by neuroscientists.

Investigators report the finding in the Aug. 2 issue of the Journal of Neuroscience. Janet Richmond, associate professor of biological sciences at the University of Illinois at Chicago, is the corresponding author.

Previously, Richmond developed a technique that allows a more precise understanding of how synaptic proteins affect release of neurotransmitter chemicals at the junctions -- the signal that enables nerve cells to issue commands.

The technique described in the new study, high-pressure freeze electron microscopy and immuno-gold staining, now provides an accurate picture of where these synaptic proteins cluster -- information previously unknown to scientists.

Co-author Robby Weimer, a post-doctoral fellow at the Cold Stream Harbor Laboratory in New York, developed the high-pressure freeze technique to view synapses while working in the laboratory of coauthor Jean-Louis Bessereau at INSERM Ecole Normale Superieure in Paris. Richmond's graduate student Elena Gracheva introduced the technique at UIC.

"It's a new technique that allows us to take a snapshot of what's going on at the neuromuscular junction and actually physically view the consequences of losing these proteins," said Richmond.

The conventional technique is to use gluteraldhyde fixation, which takes seconds or minutes to complete -- unlike the fraction of a second when using the high-pressure freeze method. Wha
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Source:University of Illinois at Chicago