NEW YORK (Dec. 13, 2007) -- For the first time, scientists at Weill Cornell Medical College in New York City have observed in real time a cellular mechanism that's crucial to how brain cells communicate.
In doing so, they've also laid to rest a competing theory as to how key cellular processes -- called endocytosis and exocytosis -- work.
The scientists published their findings in this week's online edition of Proceedings of the National Academy of Sciences (Dec. 18 print edition).
Healthy neurological function hinges on the efficient passage of information between brain cells via the synapse, and exocytosis/endocytosis is the complex trafficking mechanism that allows this to happen.
At its simplest level, exocytosis involves the packaging, transport and delivery of neurotransmitter chemicals in sac-like structures called vesicles. These vesicles move from the interior of the cell to the cell membrane, where they deliver their information-rich cargo to the synapse. Endocytosis involves a similar function in the reverse direction, with incoming vesicles being transported into the cell's interior.
The vesicles aren't discarded, however. Instead, once they release their cargo they are recycled for use in another go-round. There have been two competing theories about how that recycling occurs -- either the vesicle fragments upon delivering its cargo and must be rebuilt, or it simply empties itself like milk from a bottle which is then resealed.
"The vast bulk of the evidence suggests the former theory is actually the correct one, but it's been tempting to think of the 'resealable spout' theory, because it seems so logical and because there's been some ambiguous evidence that it might be true," says the study's co-author Dr. Timothy Ryan, professor of biochemistry at Weill Cornell Medical College.
The trouble is, no one had ever found a way to observe -- accurately and in real time -- synaptic vesicle r
|Contact: Andrew Klein|
New York- Presbyterian Hospital/Weill Cornell Medical Center/Weill Cornell Medical College