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The Laboratory
in the News

Comet’s dust is a mixed bag of the entire solar system
Livermore researchers, along with hundreds of investigators worldwide, are uncovering the mysteries underlying the history of our solar system through analysis of comet dust gathered from the Stardust mission that returned to Earth in January 2006. A series of research articles associated with the space dust appears in the December 15, 2006, issue of Science.
Stardust, which launched in 1999 to rendezvous with Comet Wild 2 in 2004, captured less than 1 milligram of the comet’s particulate material. However, this miniscule amount has been enough for Livermore scientists to determine the composition of the tiny particles.
Using the most powerful microscope in the world, Livermore’s SuperSTEM (scanning transmission electron microscope), researchers were surprised to find osbornite among the Wild 2 dust. Osbornite forms much closer to the Sun than where Wild 2 spent most of its life—outside the orbit of Neptune. Further analysis revealed a mix of silicates, sulfides, and organic matter, all of which represent material that has been scattered across the solar system. The research indicates that the early solar system was a volatile place in which materials may have been ejected from the inner regions and relocated to the outer regions.
Contact: John Bradley (925) 423-0666 (bradley33@llnl.gov).

Hawaiian corals may be older than previously believed
Researchers from Lawrence Livermore, Stanford University, the University of California (UC) at Berkeley, and UC Santa Cruz have determined that three groups of Hawaiian deep-sea corals grow more slowly and are far older than previously believed. Their research appeared in the December 7, 2006, issue of Marine Ecology Progress Series.
Using radiocarbon dating techniques, scientists calculated radial growth rates on specimens of Corallium secundum, Gerardia sp., and Leiopathes glaberrima, which were collected from the Makapuu deep-sea coral bed off the southeast coast of Oahu. Results showed that Gerardia sp. fossils, or gold corral, had radial growth rates of 14 to 45 micrometers per year and ages ranging from 450 to 2,742 years. Similarly, the scientists found that L. glaberrima, or black coral, is extremely long-lived with a growth rate less than 10 micrometers per year and a life span of around 2,380 years. By contrast, measurements on black coral samples taken near Lahaina, Maui, yielded growth rates ranging from 130 to 1,140 micrometers per year and life spans between 12 and 32 years.
Interest in the ecology and biology of deep-sea corals is increasing in response to the threat of their physical destruction, which is due, in part, to both commercial deep-sea fishing and climate change. Data from deep-sea corals also provide a valuable record of past climate and environmental change.
Contact: Tom Guilderson (925) 422-1753 (tguilderson@llnl.gov).

Proteins involved in growth of plague bacterium
Researchers from Lawrence Livermore and Pacific Northwest national laboratories have re-created growth conditions in flea carriers and mammalian hosts to uncover 89 proteins and 87 likely proteins in Yersinia pestis, the bacterium that caused the Black Death plagues. The study indicates that the abundance of these proteins changes relative to the bacterium’s virulence.
The team, led by Livermore scientists Sandra McCutchen-Maloney and Brett Chromy of the Chemistry, Materials, and Life Sciences Directorate, reports its findings in the November 2006 issue of Journal of Proteome Research. The study, which was funded by the Department of Homeland Security, identified the proteins as “unique biomarkers related specifically to growth condition.” Biomarkers associated with disease progression show promise as detection tools in public health and biodefense and can guide drug and vaccine designers in their quest to disrupt the microbe’s ability to infect. Fleas are vectors for the disease and can spread it to rodent and human hosts.
The paper follows up on a previous Livermore study investigating the proteome of Y. pestis under these same growth conditions. Both studies used comparative proteomics techniques to home in on differentially expressed proteins under conditions that represent key virulence regulators in Y. pestis. The earlier study used a gel-based screen to show the proteins, whereas the current study used a mass spectrometry-based screen. Together, these two technologies can examine a larger portion of the proteome and identify the key proteins involved in regulating virulence.
Contact: Brett Chromy (925) 422-2454 (chromy1@llnl.gov) or
Sandra McCutchen-Maloney (925) 423-5065 (smaloney@llnl.gov).

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UCRL-52000-07-3 | March 19, 2007