Biomedical Beat - A monthly digest of research news from NIGMS

IN THIS ISSUE . . .
September 20, 2005

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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 Research Around the Nation.

Cool Image: Colorful Communication

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The marine bacterium Vibrio harveyi glows when near its kind. This luminescence, which results from biochemical reactions, is part of the chemical communication used by the organisms to assess their own population size and distinguish themselves from other types of bacteria. But V. harveyi only light up when part of a large group. This communication, called quorum sensing, speaks for itself here on a lab dish, where more densely packed areas of the bacteria show up blue. Other types of bacteria use quorum sensing to release toxins, trigger disease, and evade the immune system. Courtesy of Bonnie Bassler, a microbial geneticist at Princeton University.

Bassler home page
Article on Bassler and quorum sensing

Chicken Eggs Offer Better Way to Produce Important Drug

In recent years, a new class of drugs called monoclonal antibodies has become an important method for treating cancer and other illnesses. Currently, monoclonal antibodies are produced by inserting the genes encoding these proteins into cultured hamster or mouse cells. But the high cost of this technique has prompted scientists to look for a better way. With NIGMS funding in the form of a small business innovation grant, biologist Lei Zhu of Origen Therapeutics has figured out how to make monoclonal antibody drugs in chicken eggs. She found that extracting the therapeutic proteins from egg whites was straightforward and efficient. In lab tests, the antibody proved to be even more effective at killing cancer cells than were antibodies made by traditional means.

Full story
Origen Therapeutics home page
Article abstract (from the September 2005 issue of Nature Biotechnology)

Disease-Causing Fungi Evade Detection by Changing Look

Colonies of Candida albicans, the most common disease-causing fungus in humans. Courtesy of Felice Frankel.
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Caption: Colonies of Candida albicans, the most common disease-causing fungus in humans. Courtesy of Felice Frankel.

Just as friends recognize you by your outward appearance, your immune cells recognize a microbe by its surface features. But fungal microbes, which are now the fastest growing cause of hospital-acquired infections, can rapidly change parts of their surfaces and escape immune detection. A team of geneticists led by Gerald Fink of the Whitehead Institute for Biomedical Research, has discovered how fungi transform themselves. They make use of DNA elements known as tandem repeats—recurring, identical units of DNA found on chromosomes. By varying the number of repeats in genes that code for cell-surface proteins, fungi change the way they look, allowing them to go incognito in the body. These findings help explain why fungal infections can be such a problem and could lead to new targets for drugs that fight these infections.

Full story
Fink home page
Article abstract (from the September 2005 issue of Nature Genetics)

Worm Offers Clues on Plague, Deadliness

C. elegans, the tiny worm that Aballay uses to study plague bacteria, as featured on the cover of EMBO Reports. Courtesy of Diane Jarsocrak
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Caption: C. elegans, the tiny worm that Aballay uses to study plague bacteria, as featured on the cover of EMBO Reports. Courtesy of Diane Jarsocrak.

In the 14th century, one-third of Europe’s population died from the bacterium that causes plague, Yersinia pestis. Today, this bacterium is on a short list of possible bioweapons. Microbiologist Alejandro Aballay of Duke University Medical Center tracked down individual proteins that make plague so lethal. In addition to using mice, he developed a new model system for studying plague—the microscopic roundworm, Caenorhabditis elegans. His work suggests that plague bacteria use similar methods to infect worms and humans, including a previously uncharacterized family of proteins. Because C. elegans develop quickly and are easy to manipulate genetically, using them to study plague may rapidly accelerate our understanding of how the bacterium causes plague and may help mitigate any future outbreaks.

Full story
Aballay home page
Article abstract (from the issue of EMBO Reports)

Profiles in Discovery: Malaria and Protein Design

David Baker Dyann Wirth

How does malaria, the oldest disease known to humankind, spread so quickly through the developing world? What secrets hide inside a parasite’s DNA that enables it to ignore antimalarial drugs? Geneticist Dyann Wirth (right) at the Harvard School of Public Health is investigating the answers. Read about her global research in “Science Without Borders” in the September 2005 issue of the NIGMS publication Findings. Also check out "The Family Business" to learn how world-class computational biologist David Baker (left), who never took a computer class in his life, uses a self-designed computer program to model protein shapes and design proteins never before found in nature.

Science Without Borders
The Family Business
Wirth home page
Baker home page and predicting protein structures at home project

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