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SCIENCE BRIEFS
BY BETSY HANSON & KRISTINE KELLY
Aquatic motion detectors. Fish detect the motion of water with a sensory system
called the lateral line, a row of clustered sensory receptors known as
neuromasts. Each sensory cell is innervated by a nerve fiber that extends
from a ganglion located near the ear. Neuromasts form from a stream of
cells that migrates along the animal from the ear to the tail. This stream
of cells also serves during the organism’s development as a scaffold
that guides the migration of the nerve fibers and supporting cells called
glia. Studying zebrafish, Hernán López-Schier and A. James Hudspeth have
discovered that mutant animals that lack glia develop twice the usual
number of neuromasts, suggesting that glia play a role in inhibiting the
overproduction of neuromasts. The finding provides insight into the genetic
basis for changes in developmental timing — inherited sensory
alterations that might allow a fish to colonize new niches, avoid
predators, or capture novel prey. Hudspeth is F.M. Kirby Professor and head
of the Laboratory of Sensory Neuroscience.
Proceedings of the National Academy of Sciences, February 1, 2005
Old bottle, new vaccine. Just one dose of the vaccine against yellow fever protects
against the disease for 30 years or more, a fact that is crucial in
tropical Africa and South America, where the virus is endemic and few
people have the chance to be vaccinated more than once. Now Charles Rice and
colleagues at the NYU School of Medicine have taken an important step
toward using the yellow fever vaccine against another tropical disease
— malaria. They placed a gene from the malaria parasite into 17D, as
the yellow fever vaccine is known, and then injected malaria-infected mice
with the hybrid. The single injection greatly reduced the level of malaria
parasites in the livers of the mice and conferred lasting resistance
against later exposure. The study opens the door to using 17D as the basis
for vaccines against many other infections, including AIDS. Rice is Maurice
R. and Corinne P. Greenberg Professor and head of the Laboratory of
Virology and Infectious Disease.
Journal of Experimental Medicine, January 17, 2005
Changing channels. Two new studies by David
Gadsby’s laboratory provide some hints on
what does, and does not, regulate the activity of the cystic fibrosis
chloride channel (CFTR), which allows salts to move in and out of the
body’s cells. By deleting different segments of the protein, Gadsby
and colleagues showed that two unique parts of the CFTR that were thought
to regulate the channel, first seen in a crystal structure published last
year, actually do not. However, when Gadsby and Rockefeller’s Brian Chait examined
several of the sites in the CFTR where signal-mediated phosphorylation
occurs, they found that one amino acid in particular is important for
helping the channel distinguish signals from noise. When this site is
phosphorylated — when a phosphate group is attached to it —
only a strong stimulus can activate the CFTR. Mutations to the site,
meanwhile, cause the channel to become much more sensitive. The CFTR is one
member of a family that also includes proteins involved in cancer
multi-drug resistance and hypoglycemia, and an understanding of how the
CFTR protein works may shed light on how other members of the family
function. Gadsby is head of the Laboratory of Cardiac and Membrane
Physiology.
Journal of General Physiology, January 2005, February 2005
Short stopper. A recent paper by Titia
de Lange and Jacqueline J. L. Jacobs shows that
a protein called p16INK4a is important for detecting when strands of DNA
called telomeres have become too short. Telomeres act as caps that get
shorter with every cell division, as chromosomes lose a small amount of DNA
each time a cell replicates. They protect important genetic sequences from
getting lost. However, extremely short telomeres can destabilize the
structure of a chromosome, making breaks and rearrangements that lead to
cancer more likely. de Lange and Jacobs found that p16INK4a can cause a
cell to stop growing when it senses very short telomeres. The role of
p16INK4a in this process, called telomere-directed senescence, has been
controversial, and de Lange and Jacobs hope the new data will aid in the
understanding of the genetics behind tumorigenesis. de Lange is Leon Hess
Professor and head of the Laboratory of Cell Biology and Genetics.
Current Biology, December
29th, 2004
May 13, 2005
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