Biomedical Beat - A monthly digest of research news from NIGMS

IN THIS ISSUE . . .
May 21, 2008

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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. To check out free NIGMS publications, go to the order form.

Cool Image: Glowing Glycans

Sugars light up the cells in this jaw of a 3-day-old zebrafish embryo and highlight a scientific first: labeling and tracking the movements of sugar chains called glycans in a living organism.
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Sugars light up the cells in this jaw of a 3-day-old zebrafish embryo and highlight a scientific first: labeling and tracking the movements of sugar chains called glycans in a living organism. Here, recently produced glycans (red) are on the cell surface while those made earlier in development (green) have migrated into the cells. In some areas, old and new glycans mingle (yellow). A better understanding of such traffic patterns could shed light on how organisms develop and may uncover markers for disease, such as cancer. Courtesy of chemical biologist Carolyn Bertozzi, University of California, Berkeley.

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Bertozzi lab home page
Article abstract (from the May 2 issue of Science)

DNA Clumping Mystery Unraveled

Epigenetic research aims to explain how traits can be inherited without changes in DNA sequence. Researchers know that a key player in epigenetics is chromatin, a structure that wraps DNA in a clumpy cloak and regulates access to it by loosening or tightening its clasp. Now, researchers show how changes in the pattern of chromatin clumping are inherited with no effect on DNA sequence. Geneticist Rob Martienssen of Cold Spring Harbor Laboratory found that just before a yeast cell unwraps its DNA and divides, a mechanism called RNA interference "copies" the chromatin clumping pattern and assures that it's passed to daughter cells.

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Martienssen lab home page
Article abstract (from the April 8 issue of Current Biology)

Evolutionary Link Confirmed with Ancient Dino Protein

Evolutionary relationships of major vertebrate groups based on similarities in a protein. Courtesy of Chris Organ.
Evolutionary relationships of major vertebrate groups based on similarities in a protein. Courtesy of Chris Organ.
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Analysis of 68 million-year-old collagen molecule fragments preserved in a T. rex femur has confirmed what paleontologists have said for decades: Dinosaurs are close relatives of chickens, ostriches, and to a lesser extent, alligators. The Harvard University research team, including NIGMS-supported postdoctoral research fellow Chris Organ, used sophisticated statistical and computational tools to compare the ancient protein to ones from 21 living species. Because evolutionary processes produce similarities across species, the methods and results may help illuminate other areas of the evolutionary tree.

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Organ home page
Article abstract (from the April 25 issue of Science)

Heparin Contaminant Identified

Scientists have detected and chemically identified the contaminant that tainted batches of the blood-thinner heparin and triggered dozens of deaths in the United States. The researchers also proved that the contaminant causes the same reactions in pigs, which are biochemically very similar to people. These discoveries came from research teams led by Ram Sasisekharan, a carbohydrate chemist at the Massachusetts Institute of Technology. The research suggests that a simple test could monitor heparin supplies, helping to ensure patient safety.

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Sasisekharan lab home page
Article abstracts 1, 2 (from April 23 issues of Nature Biotechnology and the New England Journal of Medicine)

Human Culture Affects Our Gene Activity

Scientists have proven that we actually are products of our environment—right down to what genes are turned on or off. While at North Carolina State University, geneticist Greg Gibson and colleagues studied three genetically similar Moroccan populations that differed in where and how they lived. The activity of up to 30 percent of genes varied depending on whether an individual was a desert nomad, mountain agrarian, or coastal urbanite. The scientists concluded that, in the search to understand the root causes of disease, studying links between genes and diseases is not enough—we have to include the environment too.

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Gibson lab home page (NCSU)
Article abstract (from the April 25 issue of PLoS Genetics)