Ars Technica: One of the least hospitable places on Earth, Antarctica’s McMurdo Dry Valleys, features a frigid desert with high winds, rocky ground, extremely low humidity, and minimal ice cover. In fact, NASA has used it to simulate conditions on Mars. Nevertheless, life exists in the form of bacteria, which have been found to live under the ice in super-salty lakebeds. Researchers studying Lake Vida, one of the largest lakes, have found it to be not only extremely cold, at −12 °C, but also rich in organic compounds. It hosts at least 32 species of bacteria from 8 different phyla, they report in a paper published online yesterday in the Proceedings of the National Academy of Sciences. Because the chemicals differ among the different lakes, the researchers propose that each could host distinct ecosystems with different sources of chemical energy. Such findings lend credence to the possibility of similar ecosystems on other icy worlds such as Europa or Mars.
Science News: The progression over time of a comatose brain’s ability to distinguish sound patterns appears to be linked to the likelihood that the patient will eventually awaken. Marzia De Lucia of the University of Lausanne in Switzerland and her team studied 30 coma patients who had suffered heart attacks. For the first 24 hours, all of the patients underwent standard therapeutic hypothermia to prevent brain damage. During that time, De Lucia played various sounds and recorded the patients’ brain activity. All 30 of the patients’ brains showed the ability to discriminate between the sounds. The next day, after the therapeutic hypothermia was finished, the patients were tested again. Over the next three months, all of the patients whose brains showed improved sound discrimination had woken up. Of the patients who did not improve, many died. De Lucia believes that the progression of the ability to distinguish sounds is a clear predictor of likelihood of survival. Her team is now repeating the test on a larger population of patients, and hopes that their study may help doctors provide more timely treatment for coma patients.
BBC: A team of researchers studying the effects of ice ages on Europe’s small mammal populations has discovered that there have been several genetically distinct populations of lemmings over time. By examining DNA from fossils in cave sites in Belgium, the researchers were able to study the lemming populations during the Late Pleistocene, the era from 11 700 to around 126 000 years ago. Team member Ian Barnes of Royal Holloway University in the UK said that the researchers had originally expected to find a single species of lemming whose population had varied. Instead they found that each ice age was followed by the wholesale replacement of the previous lemming population with a new, genetically distinct population, probably from Eastern Europe or Russia, that recolonized the area. Studying the instability in the population of a small mammal that would not have been hunted by humans may help scientists understand the fates of larger animals that disappeared from Europe during the same time period. Whether megafauna species were hunted to extinction or whether environmental changes were responsible has been a matter of open debate.
New York Times: For the first time, magnetic resonance imaging (MRI) tools have been used to study the progression of Parkinson’s disease in living patients, writes James Gorman for the New York Times. The disease kills brain cells and causes the affected parts of the brain to shrink. Until now, the affected areas were buried so deep that they could only be studied in patients who had died. Now, Suzanne Corkin at MIT and colleagues, whose paper appears in the Archives of Neurology, have developed a method using four different varieties of MRI to get four different images, which they then combine into a single image. From examining those images, the researchers determined that it’s the substantia nigra, an area of the brain involved in movement, that shows the first signs of damage. As the disease progresses, it begins to affect the basal forebrain, which is involved in memory and attention. Symptoms can vary widely, however, among Parkinson’s patients. The new technique is just one step along the way to understanding and treating the disease.