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Archive - Jun 12, 2009

Potential Target for Gout Treatment Is Identified

Researchers at Johns Hopkins and the University of Texas-Houston have shown that a gene, located in a chromosome 4 region statistically associated with gout, is functionally associated with the disease. The gene is ABCG2 (ATP-binding cassette, subfamily G, 2) and the researchers showed that it is a previously unidentified urate efflux transporter. The researchers further showed that the native ABCG2 protein is located in the brush border membrane of proximal kidney tubule cells where it mediates renal urate secretion. Introduction of a common SNP mutation into the gene resulted in 53% reduced urate transport rates in an experimental model. Data from a population-based study supports the fact that this particular SNP is a causal variant in the gout-associated region on chromosome 4. The authors also said that their data indicates that this common casual variant is responsible for at least 10 percent of all gout cases in whites. Noting that gout affects approximately 3 million people in the United States and that present treatments are often insufficient, the researchers suggested that ABCG2 represents an attractive drug target. This work was published online on June 8 in PNAS. Gout is a disease hallmarked by elevated levels of uric acid in the bloodstream. In this condition, crystals of monosodium urate, a uric acid salt, are deposited on the articular cartilage of joints, tendons, and surrounding tissues. The disease is marked by transient painful attacks of acute arthritis initiated by crystallization of urates within and about the joints, and can eventually lead to chronic gouty arthritis and the deposition of masses of urates in joints and other sites. [PNAS abstract]

Unique “Snow Roots” Found in Mountain Plant

In a remote region of the Russian Caucasus Mountains, a previously unknown and entirely unique form of plant root has been discovered. The root belongs to the small alpine plant Corydalis conorhiza and, unlike normal roots that grow into the soil, these roots extend upward, against gravity, through layers of snow. Given this novel behavior, the scientists have termed them “snow roots.” “This is a completely new discovery," said Dr. Johannes Cornelissen, the senior author of the study. "Snow roots are thus far unknown and a spectacular evolutionary phenomenon." The team made its discovery high up in the Caucasus Mountains, where the ground remains covered in snow for much of the year. As the snow melted at the height of summer, the scientists noted that C. conorhiza plants were surrounded by a network of above-ground roots, stretching uphill and to each side for around 50 cm. During the spring and perhaps also winter, these roots extend into the surrounding snow and during the summer they die and decompose, which may explain how they had remained undiscovered. C. conorhiza also possesses normal roots which anchor the plant to the ground and take up nutrients such as phosphorus and nitrogen. Cornelissen's team hypothesized that the additional snow roots allow C. conorhiza to take nitrogen directly from the snow. Many mountain plants take up nitrogen from melted snow soaking into the ground only after snow melt. However, an impenetrable ice crust prevents C. conorhiza from doing this, and therefore the plant is forced to depend upon the snow roots. Further study confirmed that the snow roots are anatomically very different from normal soil roots, and that they are specifically adapted for the fast uptake and transport of nitrogen. This work was published online on June 4 in Ecology Letters.