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Archive - Oct 12, 2011

Naked Mole Rat Genome Sequenced; Clues to Longevity Sought

Scientists have sequenced the complete genome of the naked mole rat, a pivotal step to understanding the animal's extraordinarily long life and good health. A colony of more than 2,000 naked mole rats at The University of Texas (UT) Health Science Center at San Antonio contributed to the findings, published online on October 12, 2011 in the journal Nature. "If we understand which genes are different or are expressed differently in naked mole rats — compared to short-lived mice that clearly have poor defenses against aging and cancer — we might find clues as to why the naked mole rat is able to extend both health span and longevity, as well as fight cancer, and this information could be directly relevant and translatable to humans," said Dr. Rochelle Buffenstein, professor of physiology at the Barshop Institute for Longevity and Aging Studies, part of the UT Health Science Center San Antonio. Dr. Buffenstein worked on the study with Dr. Thomas Park, of the University of Chicago; Dr. Vadim Gladyshev, of Harvard Medical School; scientists at the Beijing Genomics Institute; and other collaborators. The mouse-sized naked mole rat is the longest-lived rodent known, surviving up to 31 years in captivity. This is much longer than its laboratory rodent relatives, and the naked mole rat maintains good health and reproductive potential well into its third decade. Naked mole rats live underground in large family groups, like termites and bees, with only a single breeding female. These social rodents are extremely tolerant of life in low oxygen and high levels of carbon dioxide. The naked mole rat's capacity to resist cancer and maintain protein integrity in the face of oxidative damage makes it an ideal animal model for aging and biomedical research, Dr. Buffenstein said.

Diabetes Advance: Scientists Breathe New Life into Aging Beta Cells

As a person ages, the ability of his or her beta cells to divide and make new beta cells declines. By the time children reach the age of 10 to 12 years, the ability of these insulin-producing cells to replicate greatly diminishes. If these beta cells are destroyed—as they are in type 1 diabetes—treatment with the hormone insulin becomes essential to regulate blood glucose levels and allow energy to be obtained from food. Now, longtime JDRF (Juvenile Diabetes Research Foundation)-funded researchers at Stanford University have identified a pathway responsible for this age-related decline, and have shown that they can manipulate it to make older beta cells act young again—and start dividing. The research, published online on October 12, 2011 in Nature, provides the most complete picture to date of the molecular and biochemical mechanisms that bring beta cell regeneration to a near halt as beta cells age. These findings may help pave a path for developing strategies to restore beta cell number to treat both type 1 and type 2 diabetes. In their study, the researchers, led by Dr. Seung Kim of Stanford University, found that a protein called PDGF, or platelet-derived growth factor, and its receptor send beta cells signals to start dividing via an intricate pathway that controls the levels of two proteins in the beta cell nucleus, where cell division is orchestrated. Working with young mice, Dr. Kim and his team found that PDGF binds to its receptor on the beta cell's surface and controls the level of these regulating proteins allowing cells to divide. However, in older mice, they discovered that beta cells lose PDGF receptors, and that this age-related change prevents beta cells from dividing. Dr.

First Practical Test to Date and Authenticate Priceless Silk Treasures

Scientists are reporting development of the first fast and reliable scientific method to determine the age and authenticity of priceless silk tapestries and other silk treasures -- such as Civil War General Phillip Sheridan's famous red-and-white battle flag -- in museums and other collections around the world. A report on the work appears in the October 1, 2011 issue of the American Chemical Society’s journal Analytical Chemistry. Dr. Mehdi Moini and colleagues at the Smithsonian Institution point out that for thousands of years, silk fibers, consisting of natural protein unwound from the cocoons of the silkworm, have been woven into not just garments, but wall hangings, tapestries, carpets, and painted silk artworks. Until now, however, there has been no practical scientific way to tell whether a silk tapestry is a well-preserved example from the Fontainebleu series from the 1540s or a copy made just last week. In many cases, scientists could not use the familiar carbon-14 dating process, because it involves taking samples of material large enough to cause visible damage to the silk object. The scientists’ solution is a new test that tracks time-related deterioration of the amino acid building blocks in silk protein. As silk ages, the so-called L-amino acids in its protein change into so-called D-amino acids. The D/L ratio provides a highly accurate measure of a silk object's age, to within 50-100 years, and indicates whether it is deteriorating and needs conservation work. Archaeologists have previously used the D/L approach to date ancient teeth and bone, but Dr. Moini's team simplified the technique and adapted it for silk. The researchers demonstrated the test, called "CE-MS," on Sheridan's flag, a Fontainebleu tapestry, ancient silks from China, and other old samples from masterpieces in museums around the world.