Biomedical Beat - A monthly digest of research news from NIGMS

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 to the findings. To read additional news items, visit NIGMS News.

Cool Image: Cellular Traffic

Courtesy of postdoctoral fellow Alexey Sharonov and chemist Robin Hochstrasser.
High res. image (108 KB JPEG)
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.

Hochstrasser lab home page
NIH 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.

Full story
Thomson home page
Article abstract (from the March 24, 2006, issue of Nature Biotechnology)

Advances Made in RNAi

Ribbon representation of Dicer. Courtesy of Doudna.
High res. image (43 KB JPEG)
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.

Full story (Doudna)
Full story (Wilkinson)
Doudna home page
Wilkinson home page [Link no longer active]
Doudna article abstract (from January 13, 2006, issue of Science)
Wilkinson article abstract (from January 15, 2006, issue of Genes & Development)

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 bacterium.

Full story
Chiu lab
Article abstract (from the February 2, 2006, issue of Nature)

New Teams to Model Pandemic Flu, Other Infectious Outbreaks

MIDAS Logo
High res. image (28 KB JPEG)
 

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 Medical School.

Full story (MIDAS) [Link no longer active]
Full story (Lipsitch findings)
MIDAS home page
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