From the ArcaMax Publishing, Science & Technology Newsletter:
http://www.arcamax.com/news/technology/s-345043-335921
BALTIMORE (UPI) -- U.S. neuroscientists say they have discovered how
body tissue aids new peripheral nerve cells to kill neighboring
nerves.
The Johns Hopkins University scientists said the developing nervous
system makes far more nerve cells than are needed to ensure target
organs and tissues are properly connected to it. So as nerves connect
to target organs, they somehow compete with each other, resulting in
some living and some dying.
Now, using a combination of computer modeling and molecular biology,
the researchers have discovered the mechanism behind that action.,
"It was hard to imagine how this competition happens because the
signal that leads cells to their targets also is responsible for
keeping them alive, which begs the question: How do half of them die?"
said Professor David Ginty.
The scientists found target tissues innervated by so-called peripheral
neurons coax nerves to grow toward them by releasing nerve growth
factor protein, or NGF. Once the nerve reaches its target, NGF changes
from a growth cue to a survival factor. And, when some populations of
nerve cells are deprived of NGF, they die.
The study was detailed in the April 18th issue of Science magazine.