IN THIS ISSUE . . .
February 21, 2006
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The National Institute of General Medical Sciences (NIGMS),
one of the National Institutes of Health, supports all research
featured in this digest. Although only the lead scientists
are named, coworkers and other collaborators also contributed
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Cool Image: Cellular Traffic
Like tractor-trailers on a highway, small sacs called
vesicles transport substances within cells. This image tracks
the motion of vesicles in a living cell. The short red and
yellow marks offer information on vesicle movement. The
lines spanning the image show overall traffic trends. Typically,
the sacs flow from the lower right (blue) to the upper left
(red) corner of the picture. Such maps help researchers
follow different kinds of cellular processes as they unfold.
Courtesy of postdoctoral fellow Alexey Sharonov and chemist
Robin Hochstrasser, both at the University of Pennsylvania,
who also collaborate in a cellular imaging project supported
by the NIH Roadmap for Medical Research.
lab home page
cellular imaging home page
Fresh Foundation for Human Embryonic Stem Cells
Human embryonic stem cells have the remarkable ability to
turn into any type of cell in the body, so they hold enormous
potential as a source of replacement cells for treating a
myriad of diseases. But scientists have worried that the animal
products used to derive and maintain the cells in the laboratory
could harbor viruses or foreign molecules, limiting their
use for human therapies. Now, a team of researchers led by
developmental biologist James Thomson of the University of
Wisconsin-Madison have developed a stem cell culture medium
free of animal products. While stem cells grown in the presence
of animal products remain useful for basic biology studies
of stem cells, the team has cleared a major hurdle in the
future use of embryonic stem cells for treating human disease.
As part of this study, Thomson’s team used the new
culture medium to derive two new human embryonic stem cell
lines. NIGMS support was limited to the research on existing,
federally approved cell lines.
abstract (from the March 24, 2006, issue of Nature Biotechnology)
Advances Made in RNAi
Caption: Ribbon representation
of Dicer. Courtesy of Doudna.
The discovery of RNA interference (RNAi) may transform biology
and medicine the way plastics revolutionized manufacturing.
Discovered less than 10 years ago, RNAi is a natural process
that plants and animals use to reduce the expression of specific
genes. Researchers extol its potential to shed light on many
cellular activities and to treat numerous diseases. Recently,
biochemist Jennifer Doudna of the University of California,
Berkeley, used X-ray crystallography to reveal the detailed,
3-D structure of Dicer, a key enzyme used in RNAi. This axe-shaped
structure has already helped scientists better understand
how RNAi works. Molecular biologist Miles Wilkinson of the
University of Texas M.D. Anderson Cancer Center harnessed
RNAi to silence a gene only in a specific cell type. This
technique, which can be tailored to target any tissue in an
organism, provides a powerful new tool to examine the function
of individual genes.
home page [Link no longer active]
article abstract (from January 13, 2006, issue of Science)
article abstract (from January 15, 2006, issue of Genes
Understanding How Viruses Infect
The secret to a virus’ success is its ability to
inject its DNA into a host cell and then transfer the genetic
material into baby viruses so the infection can spread.
Structural biologist Wah Chiu of the Baylor College of Medicine
has dissected some of the key details, potentially pointing
to new ways to foil this process. Using computer technology
and a powerful electron cryomicroscope that can see very
small structures in vivid detail, Chiu proposed how a tiny
virus called a bacteriophage might assault Salmonella,
a bacterium that causes food poisoning. His findings reveal
that tiny viral motors coil the DNA into a compact spiral
that can later be easily unwound and inserted into a new
abstract (from the February 2, 2006, issue of Nature)
New Teams to Model Pandemic Flu, Other Infectious Outbreaks
Four new scientific teams have joined the NIGMS Models
of Infectious Disease Agent Study (MIDAS) to better understand
the spread of infectious diseases and the potential impact
of public health measures. They’ll collaborate with
existing research teams to develop computer modeling techniques
for simulating pandemic influenza and other infectious diseases.
One of the new members, epidemiologist Marc Lipsitch of
the Harvard School of Public Health, just published findings
analyzing how much time containment might buy in postponing
a flu pandemic. The new teams are led by researchers at
the University of California, Irvine; the Harvard School
of Public Health; the University of Pennsylvania School
of Veterinary Medicine; and Harvard Pilgrim Health Care/Harvard
story (MIDAS) [Link no longer active]
story (Lipsitch findings)
to MIDAS Listserv