Researchers from the University of Illinois at Chicago led by Janet Richmond, professor of biological sciences, have found a better way to observe what happens with synaptic proteins in nematode worms.
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.
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.
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. What’s more, during gluteraldhyde fixation the nematodes writhe around, releasing neurotransmitters while cells become dehydrated, causing synaptic components to get misplaced and synapses to take on a wrinkly appearance.
While slow freezing can create ice crystals that tear cell structures apart, the high-pressure technique, using liquid nitrogen to flash-freeze at minus-180 degrees Celsius, makes ice appear like liquid glass and devoid of destructive crystals.
Cross-sections taken of synapses reveal that membrane packets, or vesicles, of neurotransmitter localize in places scientists have never before seen.
The formation of ice crystals is the primary reason cryogenic freezing is viewed as impractical now. Maybe a massively scaled up version of this technology would allow Futurama to become reality.
More from the UIC press release and the abstract at the Journal of Neuroscience…